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  1. 50,000-Watt AM Stations IA | MB | MI | MN | NE | ND | ON | SD | WI | Station News | Owners | TV Captures | Links

    E-Print Network [OSTI]

    Allen, Gale

    that broadcast with a power of 50,000 Watts day and night. Some of these stations are what was once known50,000-Watt AM Stations IA | MB | MI | MN | NE | ND | ON | SD | WI | Station News | Owners | TV Captures | Links 50,000-Watt AM stations This list includes AM stations in the United States and Canada

  2. Role of <mi>Ce>4+ in the scintillation mechanism of codoped <mi>Gd>3<mi>Ga>3<mi>Al>2<mi mathvariant='normal'>Omi>12:<mi>Ce>

    SciTech Connect (OSTI)

    Wu, Yuntao; Meng, Fang; Li, Qi; Koschan, Merry; Melcher, Charles L.

    2014-10-17

    To control the time-response performance of widely used cerium-activated scintillators in cutting-edge medical-imaging devices, such as time-of-flight positron-emission tomography, a comprehensive understanding of the role of Ce valence states, especially stable Ce4+, in the scintillation mechanism is essential. However, despite some progress made recently, an understanding of the physical processes involving Ce4+ is still lacking. The aim of this work is to clarify the role of Ce4+ in scintillators by studying Ca2+ codoped Gd3Ga3Al2O12?Ce?(GGAG?Ce). By using a combination of optical absorption spectra and x-ray absorption near-edge spectroscopies, the correlation between Ca2+codoping content and the Ce4+ fraction is seen. The energy-level diagrams of Ce3+ and Ce4+ in the Gd3Ga3Al2O12 host are established by using theoretical and experimental methods, which indicate a higher position of the 5d1 state of Ce4+ in the forbidden gap in comparison to that of Ce3+. Underlying reasons for the decay-time acceleration resulting from Ca2+ codoping are revealed, and the physical processes of the Ce4+-emission model are proposed and further demonstrated by temperature-dependent radioluminescence spectra under x-ray excitation.

  3. Dust around Type Ia supernovae

    E-Print Network [OSTI]

    Wang, Lifan

    2005-01-01

    Dust around Type Ia supernovae Lifan Wang 1,2 LawrenceIa. Subject headings: Supernovae: General, Dust, Extinctionline) bands for Type Ia supernovae. (a), upper panel, shows

  4. Table 2 -Lime use and practices on Corn, major producing states, 2001 CO GA IL IN IA KS KY MI MN MO NE NY NC ND OH PA SD TX WI Area

    E-Print Network [OSTI]

    Kammen, Daniel M.

    MO NE NY NC ND OH PA SD TX WI Area Lime applied NR 85 81 85 67 16 72 55 27 65 10 57 53 NR 70 95 3 1 50 51 Lime (tons treated acre) NR 1.0 2.1 1.9 2.5 2.1 2.4 2.0 2.6 2.8 1.5 1.9 1.1 NR 1.9 1.7 NR 0.5 2 NC ND OH PA SD TX WI Area Lime applied NR 95 90 69 18 69 71 14 77 16 76 99 NR 82 80 NR 5 58 54 Lime

  5. NONPROFIT ORG DETROIT, MI

    E-Print Network [OSTI]

    Berdichevsky, Victor

    NONPROFIT ORG US POSTAGE PAID DETROIT, MI PERMIT NO 3844 College of Engineering Wayne State University 5050 Anthony Wayne Drive Room 1153 · Detroit, MI 48202 Phone (313) 577-3780 · Fax (313) 577, Wayne State University 5050 Anthony Wayne Drive Detroit, MI 48202 My first assignment for Ex

  6. New approaches for modeling type Ia supernovae

    E-Print Network [OSTI]

    Zingale, Michael; Almgren, Ann S.; Bell, John B.; Day, Marcus S.; Rendleman, Charles A.; Woosley, Stan

    2007-01-01

    runaway in Type Ia supernovae: How to run away? oIgnition in Type Ia Supernovae. II. A Three- dimensionalnumber modeling of type Ia supernovae. I. hydrodynamics.

  7. Deep acceptors trapped at threading edge dislocations in GaN J. Elsner 1;2 , R. Jones 1 , M. Haugk 2 , Th. Frauenheim 2 , M.I. Heggie 3 , S.

    E-Print Network [OSTI]

    Jones, Robert

    Deep acceptors trapped at threading edge dislocations in GaN J. Elsner 1;2 , R. Jones 1 , M. Haugk--fold coordinated in a bridge position. V Ga --O N is found to be a deep double accecptor, V Ga --(O N ) 2 is a deep defects are responsible for a deep acceptor level associated with the mid­gap yellow luminescence band. Ga

  8. Type Ia Supernovae

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservationBio-Inspired SolarAbout /Two Electron Holes in HematiteType Ia Supernovae Type Ia

  9. Type Ia Supernovae: Spectroscopic Surprises

    E-Print Network [OSTI]

    David Branch

    2003-10-23

    Recent observations have extended the range of diversity among spectra of Type Ia supernovae. I briefly discuss SN Ia explosion models in the spectroscopic context, the observed diversity, and some recent results from direct analysis with the Synow code for one normal and two peculiar SNe Ia. Relating the observational manifestations of diversity to their physical causes is looking like an ever more challenging problem.

  10. IA News Archive

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergy A plug-inPPLforLDRD Report11,SecurityHome . Form D-4-A Government of the66 IA News

  11. New approaches for modeling type Ia supernovae

    E-Print Network [OSTI]

    Zingale, Michael; Almgren, Ann S.; Bell, John B.; Day, Marcus S.; Rendleman, Charles A.; Woosley, Stan

    2007-01-01

    ich and J. Stein. On the thermonuclear runaway in Type IaSmall-Scale Stability of Thermonuclear Flames o in Type IaS. E. Woosley. The thermonuclear explosion of chandrasekhar

  12. Type Ia Supernova Explosion Models

    E-Print Network [OSTI]

    W. Hillebrandt; J. C. Niemeyer

    2000-06-21

    Because calibrated light curves of Type Ia supernovae have become a major tool to determine the local expansion rate of the Universe and also its geometrical structure, considerable attention has been given to models of these events over the past couple of years. There are good reasons to believe that perhaps most Type Ia supernovae are the explosions of white dwarfs that have approached the Chandrasekhar mass, M_ch ~ 1.39 M_sun, and are disrupted by thermonuclear fusion of carbon and oxygen. However, the mechanism whereby such accreting carbon-oxygen white dwarfs explode continues to be uncertain. Recent progress in modeling Type Ia supernovae as well as several of the still open questions are addressed in this review. Although the main emphasis will be on studies of the explosion mechanism itself and on the related physical processes, including the physics of turbulent nuclear combustion in degenerate stars, we also discuss observational constraints.

  13. Turbulence-Flame Interactions in Type Ia Supernovae

    E-Print Network [OSTI]

    Aspden, Andrew J; Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 50A-1148, Berkeley, CA 94720 (Authors 1, 2 & 3); Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (Author 4); Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (Author 5)

    2008-01-01

    Interactions in Type Ia Supernovae A. J. Aspden 1 , J. B.involved in type Ia supernovae (SN Ia) requires the use of ?generated by RT in type Ia supernovae should obey Bolgiano-

  14. Defining photometric peculiar type Ia supernovae

    SciTech Connect (OSTI)

    González-Gaitán, S.; Pignata, G.; Förster, F.; Gutiérrez, C. P.; Bufano, F.; Galbany, L.; Hamuy, M.; De Jaeger, T. [Millennium Institute of Astrophysics, Casilla 36-D, Santiago (Chile); Hsiao, E. Y.; Phillips, M. M. [Carnegie Observatories, Las Campanas Observatory, Casilla 601, La Serena (Chile); Folatelli, G. [Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa 277-8583 (Kavli IPMU, WPI) (Japan); Anderson, J. P., E-mail: sgonzale@das.uchile.cl [European Southern Observatory, Alonso de Córdova 3107, Casilla 19, Santiago (Chile)

    2014-11-10

    We present a new photometric identification technique for SN 1991bg-like type Ia supernovae (SNe Ia), i.e., objects with light curve characteristics such as later primary maxima and the absence of a secondary peak in redder filters. This method is capable of selecting this sub-group from the normal type Ia population. Furthermore, we find that recently identified peculiar sub-types such as SNe Iax and super-Chandrasekhar SNe Ia have photometric characteristics similar to 91bg-like SNe Ia, namely, the absence of secondary maxima and shoulders at longer wavelengths, and can also be classified with our technique. The similarity of these different SN Ia sub-groups perhaps suggests common physical conditions. This typing methodology permits the photometric identification of peculiar SNe Ia in large upcoming wide-field surveys either to study them further or to obtain a pure sample of normal SNe Ia for cosmological studies.

  15. Ideal bandpasses for type Ia supernova cosmology

    E-Print Network [OSTI]

    Davis, Tamara M.; Schmidt, Brian P.; Kim, Alex G.

    2005-01-01

    diversity of type Ia Supernovae, in preparation. Kim, A.error in measurements of supernovae depends on a periodicABSTRACT To use type Ia supernovae as standard candles for

  16. Rates and progenitors of type Ia supernovae

    E-Print Network [OSTI]

    Wood-Vasey, William Michael

    2004-01-01

    Supernovae . . . . . . . . . . . . . . . . . . . .Supernovae Found 5.1 Introduction . . . . . . . . . . . .1.2 Non-Type Ia Supernovae . . . . . . . . . . . . . . . 1.3

  17. Type Ia Supernovae: Toward the Standard Model?

    E-Print Network [OSTI]

    David Branch

    2000-12-13

    In this short review I suggest that recent developments support the conjecture that Type Ia supernovae (SNe Ia) are the complete disruptions of Chandrasekhar-mass carbon-oxygen white dwarfs in single-degenerate binary systems. The causes of the observational diversity of SNe Ia within the context of this standard model, and the implications of the model for young remnants of SNe Ia, are briefly discussed.

  18. Type Ia Supernova Carbon Footprints

    E-Print Network [OSTI]

    Thomas, R C; Aragon, C; Antilogus, P; Bailey, S; Baltay, C; Bongard, S; Buton, C; Canto, A; Childress, M; Chotard, N; Copin, Y; Fakhouri, H K; Gangler, E; Hsiao, E Y; Kerschhaggl, M; Kowalski, M; Loken, S; Nugent, P; Paech, K; Pain, R; Pecontal, E; Pereira, R; Perlmutter, S; Rabinowitz, D; Rigault, M; Rubin, D; Runge, K; Scalzo, R; Smadja, G; Tao, C; Weaver, B A; Wu, C; Brown, P J; Milne, P A

    2011-01-01

    We present convincing evidence of unburned carbon at photospheric velocities in new observations of 5 Type Ia supernovae (SNe Ia) obtained by the Nearby Supernova Factory. These SNe are identified by examining 346 spectra from 124 SNe obtained before +2.5 d relative to maximum. Detections are based on the presence of relatively strong C II 6580 absorption "notches" in multiple spectra of each SN, aided by automated fitting with the SYNAPPS code. Four of the 5 SNe in question are otherwise spectroscopically unremarkable, with ions and ejection velocities typical of SNe Ia, but spectra of the fifth exhibits high-velocity (v > 20,000 km/s) Si II and Ca II features. On the other hand, the light curve properties are preferentially grouped, strongly suggesting a connection between carbon-positivity and broad band light curve/color behavior: Three of the 5 have relatively narrow light curves but also blue colors, and a fourth may be a dust-reddened member of this family. Accounting for signal-to-noise and phase, we ...

  19. Low Mach Number Modeling of Type Ia Supernovae. II. Energy Evolution

    E-Print Network [OSTI]

    Almgren, Ann S.; Bell, John B.; Rendleman, Charles A.; Zingale, Mike

    2006-01-01

    Number Modeling of Type Ia Supernovae. II. Energy EvolutionIa. Subject headings: supernovae: general — white dwarfs —the ignition of Type Ia supernovae (SNe Ia) is critical to

  20. Turbulent Combustion in Type Ia Supernova Models

    E-Print Network [OSTI]

    F. K. Roepke; W. Hillebrandt

    2006-09-15

    We review the astrophysical modeling of type Ia supernova explosions and describe numerical methods to implement numerical simulations of these events. Some results of such simulations are discussed.

  1. IA-32 Intel Architecture Software Developer's

    E-Print Network [OSTI]

    Bernstein, Daniel

    IA-32 Intel® Architecture Software Developer's Manual Volume 1: Basic Architecture NOTE: The IA-32 Intel Architecture Software Developer's Manual consists of four volumes: Basic Architecture, Order RIGHT. INTEL PRODUCTS ARE NOT INTENDED FOR USE IN MEDICAL, LIFE SAVING, OR LIFE SUSTAINING APPLICATIONS

  2. IA-32 Intel Architecture Software Developer's

    E-Print Network [OSTI]

    IA-32 Intel® Architecture Software Developer's Manual Volume 3: System Programming Guide NOTE: The IA-32 Intel Architecture Developer's Manual consists of three books: Basic Architecture, Order Number SAVING, OR LIFE SUSTAINING APPLICATIONS. Intel may make changes to specifications and product

  3. ASTRONOMY AND ASTROPHYSICS Dark Energy, Type Ia supernovae, radiative

    Office of Scientific and Technical Information (OSTI)

    of Oklahoma Univ. of Oklahoma 79 ASTRONOMY AND ASTROPHYSICS Dark Energy, Type Ia supernovae, radiative transfer, Dark Energy, Type Ia supernovae, radiative transfer, The...

  4. Three-dimensional Numerical Simulations of Rayleigh-Taylor Unstable Flames in Type Ia Supernovae

    E-Print Network [OSTI]

    Bell, John B.

    ) instability and turbulence in accelerating a thermonuclear flame in Type Ia supernovae (SNe Ia) is well

  5. Real-time sub-<mi>Å>ngstrom...

    Office of Scientific and Technical Information (OSTI)

    Real-time sub-<mi>>ngstrom imaging of reversible and irreversible conformations in rhodium catalysts and graphene Kisielowski, Christian; Wang,...

  6. SNe Ia as a cosmological probe

    E-Print Network [OSTI]

    Meng, Xiangcun; Han, Zhanwen

    2015-01-01

    Type Ia supernovae luminosities can be corrected to render them useful as standard candles able to probe the expansion history of the universe. This technique was successful applied to discover the present acceleration of the universe. As the number of SNe Ia observed at high redshift increases and analysis techniques are perfected, people aim to use this technique to probe the equation of state of the dark energy. Nevertheless, the nature of SNe Ia progenitors remains controversial and concerns persist about possible evolution effects that may be larger and harder to characterize than the more obvious statistical uncertainties.

  7. Package `MiST' July 2, 2014

    E-Print Network [OSTI]

    Brent, Roger

    Package `MiST' July 2, 2014 Type Package Title Mixed effects Score Test for continuous outcomes topics documented: MiST-package 10 1 #12;2 linear.test MiST-package Mixed effects Score Test Description Test for association between

  8. Type Ia Supernovae Project at NERSC

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of star called a white dwarf. The majority of SN Ia explosions occur far away from our galaxy; yet, due to their enormous intrinsic brightness, outshining billions of stars, we can...

  9. Type Ia Supernovae and the Hubble Constant

    E-Print Network [OSTI]

    D. Branch

    1998-01-08

    The focus of this review is the work that has been done during the 1990s on using Type Ia supernovae (SNe Ia) to measure the Hubble constant ($H_0$). SNe Ia are well suited for measuring $H_0$. A straightforward maximum-light color criterion can weed out the minority of observed events that are either intrinsically subluminous or substantially extinguished by dust, leaving a majority subsample that has observational absolute-magnitude dispersions of less than $\\sigma_{obs}(M_B) \\simeq \\sigma_{obs}(M_V) \\simeq 0.3$ mag. Correlations between absolute magnitude and one or more distance-independent SN Ia or parent-galaxy observables can be used to further standardize the absolute magnitudes to better than 0.2 mag. The absolute magnitudes can be calibrated in two independent ways --- empirically, using Cepheid-based distances to parent galaxies of SNe Ia, and physically, by light curve and spectrum fitting. At present the empirical and physical calibrations are in agreement at $M_B \\simeq M_V \\simeq -19.4$ or -19.5. Various ways that have been used to match Cepheid-calibrated SNe Ia or physical models to SNe Ia that have been observed out in the Hubble flow have given values of $H_0$ distributed throughout the range 54 to 67 km/s Mpc$^{-1}$. Astronomers who want a consensus value of $H_0$ from SNe Ia with conservative errors could, for now, use $60 \\pm 10$ km/s Mpc^{-1}$.

  10. miRNAs in brain development

    SciTech Connect (OSTI)

    Petri, Rebecca; Malmevik, Josephine; Fasching, Liana; Åkerblom, Malin; Jakobsson, Johan

    2014-02-01

    MicroRNAs (miRNAs) are small, non-coding RNAs that negatively regulate gene expression at the post-transcriptional level. In the brain, a large number of miRNAs are expressed and there is a growing body of evidence demonstrating that miRNAs are essential for brain development and neuronal function. Conditional knockout studies of the core components in the miRNA biogenesis pathway, such as Dicer and DGCR8, have demonstrated a crucial role for miRNAs during the development of the central nervous system. Furthermore, mice deleted for specific miRNAs and miRNA-clusters demonstrate diverse functional roles for different miRNAs during the development of different brain structures. miRNAs have been proposed to regulate cellular functions such as differentiation, proliferation and fate-determination of neural progenitors. In this review we summarise the findings from recent studies that highlight the importance of miRNAs in brain development with a focus on the mouse model. We also discuss the technical limitations of current miRNA studies that still limit our understanding of this family of non-coding RNAs and propose the use of novel and refined technologies that are needed in order to fully determine the impact of specific miRNAs in brain development. - Highlights: • miRNAs are essential for brain development and neuronal function. • KO of Dicer is embryonically lethal. • Conditional Dicer KO results in defective proliferation or increased apoptosis. • KO of individual miRNAs or miRNA families is necessary to determine function.

  11. Nucleosynthesis in Type Ia Supernovae

    E-Print Network [OSTI]

    K. Nomoto; K. Iwamoto; N. Nakasato; F. -K. Thielemann; F. Brachwitz; T. Tsujimoto; Y. Kubo; N. Kishimoto

    1997-06-03

    Among the major uncertainties involved in the Chandrasekhar mass models for Type Ia supernovae are the companion star of the accreting white dwarf (or the accretion rate that determines the carbon ignition density) and the flame speed after ignition. We present nucleosynthesis results from relatively slow deflagration (1.5 - 3 % of the sound speed) to constrain the rate of accretion from the companion star. Because of electron capture, a significant amount of neutron-rich species such as ^{54}Cr, ^{50}Ti, ^{58}Fe, ^{62}Ni, etc. are synthesized in the central region. To avoid the too large ratios of ^{54}Cr/^{56}Fe and ^{50}Ti/^{56}Fe, the central density of the white dwarf at thermonuclear runaway must be as low as \\ltsim 2 \\e9 \\gmc. Such a low central density can be realized by the accretion as fast as $\\dot M \\gtsim 1 \\times 10^{-7} M_\\odot yr^{-1}$. These rapidly accreting white dwarfs might correspond to the super-soft X-ray sources.

  12. Rates and progenitors of type Ia supernovae

    SciTech Connect (OSTI)

    Wood-Vasey, William Michael

    2004-08-16

    The remarkable uniformity of Type Ia supernovae has allowed astronomers to use them as distance indicators to measure the properties and expansion history of the Universe. However, Type Ia supernovae exhibit intrinsic variation in both their spectra and observed brightness. The brightness variations have been approximately corrected by various methods, but there remain intrinsic variations that limit the statistical power of current and future observations of distant supernovae for cosmological purposes. There may be systematic effects in this residual variation that evolve with redshift and thus limit the cosmological power of SN Ia luminosity-distance experiments. To reduce these systematic uncertainties, we need a deeper understanding of the observed variations in Type Ia supernovae. Toward this end, the Nearby Supernova Factory has been designed to discover hundreds of Type Ia supernovae in a systematic and automated fashion and study them in detail. This project will observe these supernovae spectrophotometrically to provide the homogeneous high-quality data set necessary to improve the understanding and calibration of these vital cosmological yardsticks. From 1998 to 2003, in collaboration with the Near-Earth Asteroid Tracking group at the Jet Propulsion Laboratory, a systematic and automated searching program was conceived and executed using the computing facilities at Lawrence Berkeley National Laboratory and the National Energy Research Supercomputing Center. An automated search had never been attempted on this scale. A number of planned future large supernovae projects are predicated on the ability to find supernovae quickly, reliably, and efficiently in large datasets. A prototype run of the SNfactory search pipeline conducted from 2002 to 2003 discovered 83 SNe at a final rate of 12 SNe/month. A large, homogeneous search of this scale offers an excellent opportunity to measure the rate of Type Ia supernovae. This thesis presents a new method for analyzing the true sensitivity of a multi-epoch supernova search and finds a Type Ia supernova rate from z {approx} 0.01-0.1 of r{sub V} = 4.26{sub -1.93 -0.10}{sup +1.39 +0.10} h{sup 3} x 10{sup -4} SNe Ia/yr/Mpc{sup 3} from a preliminary analysis of a subsample of the SNfactory prototype search. Several unusual supernovae were found in the course of the SNfactory prototype search. One in particular, SN 2002ic, was the first SN Ia to exhibit convincing evidence for a circumstellar medium and offers valuable insight into the progenitors of Type Ia supernovae.

  13. Type Ia Supernova Intrinsic Magnitude Dispersion and the Fitting of Cosmological Parameters

    E-Print Network [OSTI]

    Kim, Alex G

    2011-01-01

    Applied to Type Ia supernovae, my strategy provides adata sets. Subject headings: Supernovae: Data Analysis andhomogeneous nature of Type Ia supernovae (SNe Ia) makes them

  14. Verifying the Cosmological Utility of Type Ia Supernovae: Implications of a Dispersion in the Ultraviolet Spectra

    E-Print Network [OSTI]

    Ellis, R. S.

    2008-01-01

    Utility of Type Ia Supernovae: Implications of a Dispersionheadings: surveys – supernovae: general – cosmologicalparameters Introduction Supernovae of Type Ia (SNe Ia) are

  15. Neutronization During Type Ia Supernova Simmering

    E-Print Network [OSTI]

    Piro, Anthony L

    2007-01-01

    Prior to the incineration of a white dwarf (WD) that makes a Type Ia supernova (SN Ia), the star "simmers" for ~1000 years in a convecting, carbon burning region. We have found that weak interactions during this time increase the neutron excess by an amount that depends on the total quantity of carbon burned prior to the explosion. This contribution is in addition to the metallicity (Z) dependent neutronization through the 22Ne abundance (as studied by Timmes, Brown, & Truran). The main consequence is that we expect a floor to the level of neutronization that dominates over the metallicity contribution when Z/Z_\\odot<2/3, and it can be important for even larger metallicities if substantial energy is lost to neutrinos via the convective Urca process. This would mask any correlations between SN Ia properties and galactic environments at low metallicities. In addition, we show that recent observations of the dependences of SNe Ia on galactic environments make it clear that metallicity alone cannot provide...

  16. Neutronization During Type Ia Supernova Simmering

    E-Print Network [OSTI]

    Anthony L. Piro; Lars Bildsten

    2007-10-08

    Prior to the incineration of a white dwarf (WD) that makes a Type Ia supernova (SN Ia), the star "simmers" for ~1000 years in a convecting, carbon burning region. We have found that weak interactions during this time increase the neutron excess by an amount that depends on the total quantity of carbon burned prior to the explosion. This contribution is in addition to the metallicity (Z) dependent neutronization through the 22Ne abundance (as studied by Timmes, Brown, & Truran). The main consequence is that we expect a floor to the level of neutronization that dominates over the metallicity contribution when Z/Z_\\odot<2/3, and it can be important for even larger metallicities if substantial energy is lost to neutrinos via the convective Urca process. This would mask any correlations between SN Ia properties and galactic environments at low metallicities. In addition, we show that recent observations of the dependences of SNe Ia on galactic environments make it clear that metallicity alone cannot provide for the full observed diversity of events.

  17. IA News Archive | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE: Alternative Fuelsof Energy ServicesContractingManagement »Hydrogen andBlog Archive IA

  18. MI high power operation and future plans

    SciTech Connect (OSTI)

    Kourbanis, Ioanis; /Fermilab

    2008-09-01

    Fermilab's Main Injector on acceleration cycles to 120 GeV has been running a mixed mode operation delivering beam to both the antiproton source for pbar production and to the NuMI[1] target for neutrino production since 2005. On January 2008 the slip stacking process used to increase the beam to the pbar target was expanded to include the beam to the NuMI target increasing both the beam intensity and power. The current high power MI operation will be described along with the near future plans.

  19. The NuMI Neutrino Beam

    E-Print Network [OSTI]

    P. Adamson; K. Anderson; M. Andrews; R. Andrews; I. Anghel; D. Augustine; A. Aurisano; S. Avvakumov; D. S. Ayres; B. Baller; B. Barish; G. Barr; W. L. Barrett; R. H. Bernstein; J. Biggs; M. Bishai; A. Blake; V. Bocean; G. J. Bock; D. J. Boehnlein; D. Bogert; K. Bourkland; S. V. Cao; C. M. Castromonte; S. Childress; B. C. Choudhary; J. A. B. Coelho; J. H. Cobb; L. Corwin; D. Crane; J. P. Cravens; D. Cronin-Hennessy; R. J. Ducar; J. K. de Jong; A. V. Devan; N. E. Devenish; M. V. Diwan; A. R. Erwin; C. O. Escobar; J. J. Evans; E. Falk; G. J. Feldman; T. H. Fields; R. Ford; M. V. Frohne; H. R. Gallagher; V. Garkusha; R. A. Gomes; M. C. Goodman; P. Gouffon; N. Graf; R. Gran; N. Grossman; K. Grzelak; A. Habig; S. R. Hahn; D. Harding; D. Harris; P. G. Harris; J. Hartnell; R. Hatcher; S. Hays; K. Heller; A. Holin; J. Huang; J. Hylen; A. Ibrahim; D. Indurthy; G. M. Irwin; Z. Isvan; D. E. Jaffe; C. James; D. Jensen; J. Johnstone; T. Kafka; S. M. S. Kasahara; G. Koizumi; S. Kopp; M. Kordosky; A. Kreymer; K. Lang; C. Laughton; G. Lefeuvre; J. Ling; P. J. Litchfield; L. Loiacono; P. Lucas; W. A. Mann; A. Marchionni; M. L. Marshak; N. Mayer; C. McGivern; M. M. Medeiros; R. Mehdiyev; J. R. Meier; M. D. Messier; D. G. Michael; R. H. Milburn; J. L. Miller; W. H. Miller; S. R. Mishra; S. Moed Sher; C. D. Moore; J. Morfin; L. Mualem; S. Mufson; S. Murgia; M. Murtagh; J. Musser; D. Naples; J. K. Nelson; H. B. Newman; R. J. Nichol; J. A. Nowak; J. O Connor; W. P. Oliver; M. Olsen; M. Orchanian; S. Osprey; R. B. Pahlka; J. Paley; A. Para; R. B. Patterson; T. Patzak; Z. Pavlovic; G. Pawloski; A. Perch; E. A. Peterson; D. A. Petyt; M. M. Pfutzner; S. Phan-Budd; R. K. Plunkett; N. Poonthottathil; P. Prieto; D. Pushka; X. Qiu; A. Radovic; R. A. Rameika; J. Ratchford; B. Rebel; R. Reilly; C. Rosenfeld; H. A. Rubin; K. Ruddick; M. C. Sanchez; N. Saoulidou; L. Sauer; J. Schneps; D. Schoo; A. Schreckenberger; P. Schreiner; P. Shanahan; R. Sharma; W. Smart; C. Smith; A. Sousa; A. Stefanik; N. Tagg; R. L. Talaga; G. Tassotto; J. Thomas; J. Thompson; M. A. Thomson; X. Tian; A. Timmons; D. Tinsley; S. C. Tognini; R. Toner; D. Torretta; I. Trostin; G. Tzanakos; J. Urheim; P. Vahle; K. Vaziri; E. Villegas; B. Viren; G. Vogel; R. C. Webber; A. Weber; R. C. Webb; A. Wehmann; C. White; L. Whitehead; L. H. Whitehead; S. G. Wojcicki; M. L. Wong-Squires; T. Yang; F. X. Yumiceva; V. Zarucheisky; R. Zwaska

    2015-07-29

    This paper describes the hardware and operations of the Neutrinos at the Main Injector (NuMI) beam at Fermilab. It elaborates on the design considerations for the beam as a whole and for individual elements. The most important design details of individual components are described. Beam monitoring systems and procedures, including the tuning and alignment of the beam and NuMI long-term performance, are also discussed.

  20. The NuMI Neutrino Beam

    E-Print Network [OSTI]

    Adamson, P; Andrews, M; Andrews, R; Anghel, I; Augustine, D; Aurisano, A; Avvakumov, S; Ayres, D S; Baller, B; Barish, B; Barr, G; Barrett, W L; Bernstein, R H; Biggs, J; Bishai, M; Blake, A; Bocean, V; Bock, G J; Boehnlein, D J; Bogert, D; Bourkland, K; Cao, S V; Castromonte, C M; Childress, S; Choudhary, B C; Coelho, J A B; Cobb, J H; Corwin, L; Crane, D; Cravens, J P; Cronin-Hennessy, D; Ducar, R J; de Jong, J K; Devan, A V; Devenish, N E; Diwan, M V; Erwin, A R; Escobar, C O; Evans, J J; Falk, E; Feldman, G J; Fields, T H; Ford, R; Frohne, M V; Gallagher, H R; Garkusha, V; Gomes, R A; Goodman, M C; Gouffon, P; Graf, N; Gran, R; Grossman, N; Grzelak, K; Habig, A; Hahn, S R; Harding, D; Harris, D; Harris, P G; Hartnell, J; Hatcher, R; Hays, S; Heller, K; Holin, A; Huang, J; Hylen, J; Ibrahim, A; Indurthy, D; Irwin, G M; Isvan, Z; Jaffe, D E; James, C; Jensen, D; Johnstone, J; Kafka, T; Kasahara, S M S; Koizumi, G; Kopp, S; Kordosky, M; Kreymer, A; Lang, K; Laughton, C; Lefeuvre, G; Ling, J; Litchfield, P J; Loiacono, L; Lucas, P; Mann, W A; Marchionni, A; Marshak, M L; Mayer, N; McGivern, C; Medeiros, M M; Mehdiyev, R; Meier, J R; Messier, M D; Michael, D G; Milburn, R H; Miller, J L; Miller, W H; Mishra, S R; Sher, S Moed; Moore, C D; Morfin, J; Mualem, L; Mufson, S; Murgia, S; Murtagh, M; Musser, J; Naples, D; Nelson, J K; Newman, H B; Nichol, R J; Nowak, J A; Connor, J O; Oliver, W P; Olsen, M; Orchanian, M; Osprey, S; Pahlka, R B; Paley, J; Para, A; Patterson, R B; Patzak, T; Pavlovic, Z; Pawloski, G; Perch, A; Peterson, E A; Petyt, D A; Pfutzner, M; Phan-Budd, S; Plunkett, R K; Poonthottathil, N; Prieto, P; Pushka, D; Qiu, X; Radovic, A; Rameika, R A; Ratchford, J; Rebel, B; Reilly, R; Rosenfeld, C; Rubin, H A; Ruddick, K; Sanchez, M C; Saoulidou, N; Sauer, L; Schneps, J; Schoo, D; Schreckenberger, A; Schreiner, P; Shanahan, P; Sharma, R; Smart, W; Smith, C; Sousa, A; Stefanik, A; Tagg, N; Talaga, R L; Tassotto, G; Thomas, J; Thompson, J; Thomson, M A; Tian, X; Timmons, A; Tinsley, D; Tognini, S C; Toner, R; Torretta, D; Trostin, I; Tzanakos, G; Urheim, J; Vahle, P; Vaziri, K; Villegas, E; Viren, B; Vogel, G; Webber, R C; Weber, A; Webb, R C; Wehmann, A; White, C; Whitehead, L; Whitehead, L H; Wojcicki, S G; Wong-Squires, M L; Yang, T; Yumiceva, F X; Zarucheisky, V; Zwaska, R

    2015-01-01

    This paper describes the hardware and operations of the Neutrinos at the Main Injector (NuMI) beam at Fermilab. It elaborates on the design considerations for the beam as a whole and for individual elements. The most important design details of individual components are described. Beam monitoring systems and procedures, including the tuning and alignment of the beam and NuMI long-term performance, are also discussed.

  1. The NuMI Neutrino Beam

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Adamson, P.; Anderson, K.; Andrews, M.; Andrews, R.; Anghel, I.; Augustine, D.; Aurisano, A.; Avvakumov, S.; Ayres, D. S.; Baller, B.; et al

    2015-10-20

    Our paper describes the hardware and operations of the Neutrinos at the Main Injector (NuMI) beam at Fermilab. It elaborates on the design considerations for the beam as a whole and for individual elements. The most important part of our design details pertaining to individual components is described. Beam monitoring systems and procedures, including the tuning and alignment of the beam and NuMI long-term performance, are also discussed.

  2. INTRODUCCI ON A LA GEOMETR IA DIFERENCIAL 1

    E-Print Network [OSTI]

    Gràcia, Xavier

    .009 Zaragoza (ESPA ~ NA) Typeset by A M S-T E X 1 #12; 2 INTRODUCCI #19; ON A LA GEOMETR #19; IA DIFERENCIAL

  3. K-corrections and spectral templates of Type Ia supernovae

    E-Print Network [OSTI]

    Hsiao, E. Y.

    2008-01-01

    templates of Type Ia supernovae E. Y. Hsiao 1 , A. Conleyobservations of low-redshift supernovae are less a?ected byobservations, stars: supernovae Department of Physics and

  4. Type Ia Supernova Hubble Residuals and Host-Galaxy Properties

    E-Print Network [OSTI]

    Kim, A. G.

    2014-01-01

    magnitudes of type Ia supernovae from multi-band lightsuch an analysis on the supernovae of the Nearby Supernovaheadings: distance scale, supernovae: general 1 Physics

  5. IA News Archive | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergy A plug-inPPLforLDRD Report11,SecurityHome . Form D-4-A Government of the66 IA

  6. IA Experts Listing 2014 | Department of Energy

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on DeliciousMathematicsEnergy HeadquartersFuelB IMSofNewsletterGuidingUpdateof EnergyDepartment of EnergyIA

  7. IA Blog Archive | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE: Alternative Fuelsof Energy ServicesContractingManagement »Hydrogen andBlog Archive IA Blog

  8. Improving Type Ia Supernova Standard Candle Cosmology Measurements Using Observations of Early-Type Host Galaxies

    E-Print Network [OSTI]

    Meyers, Joshua Evan

    2012-01-01

    Host Galaxies of Type Ia Supernovae Introduction SN Ia Hosts109 C HAPTER 1 Cosmology, Type Ia Supernovae and HostGalaxies Observations of supernovae have played a role in

  9. Three-dimensional numerical simulations of Rayleigh-Taylor unstable flames in type Ia supernovae

    E-Print Network [OSTI]

    Zingale, M.; Woosley, S.E.; Rendleman, C.A.; Day, M.S.; Bell, J.B.

    2005-01-01

    Unstable Flames in Type Ia Supernovae M. Zingale 1 , S. E.Subject headings: supernovae: general — white dwarfs —ame in Type Ia supernovae (SNe Ia) is well recognized (M¨

  10. MI Gap Clearing Kicker Magnet Design Review

    SciTech Connect (OSTI)

    Jensen, Chris; /Fermilab

    2008-10-01

    The kicker system requirements were originally conceived for the NOvA project. NOvA is a neutrino experiment located in Minnesota. To achieve the desired neutrino flux several upgrades are required to the accelerator complex. The Recycler will be used as a proton pre-injector for the Main Injector (MI). As the Recycler is the same size as the MI, it is possible to do a single turn fill ({approx}11 {micro}sec), minimizing the proton injection time in the MI cycle and maximizing the protons on target. The Recycler can then be filled with beam while the MI is ramping to extract beam to the target. To do this requires two new transfer lines. The existing Recycler injection line was designed for 10{pi} pbar beams, not the 20{pi} proton beams we anticipate from the Booster. The existing Recycler extraction line allows for proton injection through the MI, while we want direct injection from the Booster. These two lines will be decommissioned. The new injection line from the MI8 line into the Recycler will start at 848 and end with injection kickers at RR104. The new extraction line in the RR30 straight section will start with a new extraction kicker at RR232 and end with new MI injection kickers at MI308. Finally, to reduce beam loss activation in the enclosure, a new gap clearing kicker will be used to extract uncaptured beam created during the slip stack injection process down the existing dump line. It was suggested that the MI could benefit from this type of system immediately. This led to the early installation of the gap clearing system in the MI, followed by moving the system to Recycler during NOvA. The specifications also changed during this process. Initially the rise and fall time requirements were 38 ns and the field stability was {+-}1%. The 38 ns is based on having a gap of 2 RF buckets between injections. (There are 84 RF buckets that can be filled from the Booster for each injection, but 82 would be filled with beam. MI and Recycler contain 588 RF buckets.) A rough cost/benefit analysis showed that increasing the number of empty buckets to 3 decreased the kicker system cost by {approx}30%. This could be done while not extending the running time since this is only a 1% reduction in protons per pulse, hence the rise and fall time are now 57 ns. Additionally, the {+-}1% tolerance would have required a fast correction kicker while {+-}3% could be achieved without this kicker. The loosened tolerance was based on experience on wide band damping systems in the MI. A higher power wideband damping system is a better use of the resources as it can be used to correct for multiple sources of emittance growth. Finally, with the use of this system for MI instead of Recycler, the required strength grew from 1.2 mrad to 1.7 mrad. The final requirements for this kicker are listed.

  11. The distant type Ia supernova rate

    SciTech Connect (OSTI)

    Pain, R.; Fabbro, S.; Sullivan, M.; Ellis, R.S.; Aldering, G.; Astier, P.; Deustua, S.E.; Fruchter, A.S.; Goldhaber, G.; Goobar, A.; Groom, D.E.; Hardin, D.; Hook, I.M.; Howell, D.A.; Irwin, M.J.; Kim, A.G.; Kim, M.Y.; Knop, R.A.; Lee, J.C.; Perlmutter, S.; Ruiz-Lapuente, P.; Schahmaneche, K.; Schaefer, B.; Walton, N.A.

    2002-05-20

    We present a measurement of the rate of distant Type Ia supernovae derived using 4 large subsets of data from the Supernova Cosmology Project. Within this fiducial sample,which surveyed about 12 square degrees, thirty-eight supernovae were detected at redshifts 0.25--0.85. In a spatially flat cosmological model consistent with the results obtained by the Supernova Cosmology Project, we derive a rest-frame Type Ia supernova rate at a mean red shift z {approx_equal} 0.55 of 1.53 {sub -0.25}{sub -0.31}{sup 0.28}{sup 0.32} x 10{sup -4} h{sup 3} Mpc{sup -3} yr{sup -1} or 0.58{sub -0.09}{sub -0.09}{sup +0.10}{sup +0.10} h{sup 2} SNu(1 SNu = 1 supernova per century per 10{sup 10} L{sub B}sun), where the first uncertainty is statistical and the second includes systematic effects. The dependence of the rate on the assumed cosmological parameters is studied and the redshift dependence of the rate per unit comoving volume is contrasted with local estimates in the context of possible cosmic star formation histories and progenitor models.

  12. Dark matter ignition of type Ia supernovae

    E-Print Network [OSTI]

    Bramante, Joseph

    2015-01-01

    Recent studies of low redshift type Ia supernovae (SNIa) indicate that half explode from less than Chandrasekhar mass white dwarfs, implying ignition must proceed from something besides the canonical criticality of Chandrasekhar mass SNIa progenitors. We show that $0.1-10$ PeV mass asymmetric dark matter, with imminently detectable nucleon scattering interactions, can accumulate to the point of self-gravitation in a white dwarf and collapse, shedding gravitational potential energy by scattering off nuclei, thereby heating the white dwarf and igniting the flame front that precedes SNIa. We combine data on SNIa masses with data on the ages of SNIa-adjacent stars. This combination reveals a $ 3 \\sigma$ inverse correlation between SNIa masses and ignition ages, which could result from increased capture of dark matter in 1.4 versus 1.1 solar mass white dwarfs. Future studies of SNIa in galactic centers will provide additional tests of dark-matter-induced type Ia ignition. Remarkably, both bosonic and fermionic SNI...

  13. Random Walker Ranking for NCAA Division I-A Football

    E-Print Network [OSTI]

    Porter, Mason A.

    Random Walker Ranking for NCAA Division I-A Football Thomas Callaghan, Peter J. Mucha, and Mason A the top two NCAA Division I-A college football teams in a National Championship game at the end of each in accurately ranking or even agreeing on a ranking methodology for college football lies in two factors

  14. Search for surviving companions in type Ia supernova remnants

    SciTech Connect (OSTI)

    Pan, Kuo-Chuan [Physik Department, Universität Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Ricker, Paul M. [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Taam, Ronald E., E-mail: kuo-chuan.pan@unibas.ch, E-mail: pmricker@illinois.edu, E-mail: r-taam@northwestern.edu, E-mail: taam@asiaa.sinica.edu.tw [Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)

    2014-09-01

    The nature of the progenitor systems of type Ia supernovae (SNe Ia) is still unclear. One way to distinguish between the single-degenerate scenario and double-degenerate scenario for their progenitors is to search for the surviving companions (SCs). Using a technique that couples the results from multi-dimensional hydrodynamics simulations with calculations of the structure and evolution of main-sequence- (MS-) and helium-rich SCs, the color and magnitude of MS- and helium-rich SCs are predicted as functions of time. The SC candidates in Galactic type Ia supernova remnants (Ia SNR) and nearby extragalactic Ia SNRs are discussed. We find that the maximum detectable distance of MS SCs (helium-rich SCs) is 0.6-4 Mpc (0.4-16 Mpc), if the apparent magnitude limit is 27 in the absence of extinction, suggesting that the Large and Small Magellanic Clouds and the Andromeda Galaxy are excellent environments in which to search for SCs. However, only five Ia SNRs have been searched for SCs, showing little support for the standard channels in the singe-degenerate scenario. To better understand the progenitors of SNe Ia, we encourage the search for SCs in other nearby Ia SNRs.

  15. THE ULTRAVIOLET BRIGHTEST TYPE Ia SUPERNOVA 2011de

    SciTech Connect (OSTI)

    Brown, Peter J., E-mail: pbrown@physics.tamu.edu [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843 (United States)

    2014-11-20

    We present and discuss the ultraviolet (UV)/optical photometric light curves and absolute magnitudes of the Type Ia supernova (SN Ia) 2011de from the Swift Ultraviolet/Optical Telescope. We find it to be the UV brightest SN Ia yet observed—more than a factor of 10 brighter than normal SNe Ia in the mid-ultraviolet. We find that the UV/optical brightness and broad light curve evolution can be modeled with additional flux from the shock of the ejecta hitting a relatively large red giant companion separated by 6 × 10{sup 13} cm. However, the post-maximum behavior of other UV-bright SNe Ia can also be modeled in a similar manner, including objects with UV spectroscopy or pre-maximum photometry which is inconsistent with this model. This suggests that similar UV luminosities can be intrinsic or caused by other forms of shock interaction. The high velocities reported for SN 2011de make it distinct from the UV-bright ''super-Chandrasekhar'' SNe Ia and the NUV-blue group of normal SNe Ia. SN 2011de is an extreme example of the UV variations in SNe Ia.

  16. UNU-IAS Policy Report Biofuels in Africa

    E-Print Network [OSTI]

    UNU-IAS Policy Report Biofuels in Africa Impacts on Ecosystem Services, Biodiversity and Human Well-being #12;#12;UNU-IAS Policy Report Biofuels in Africa Impacts on Ecosystem Services, Biodiversity and Human Research (CSIR) South Africa The views expressed in this publication are those of the authors and do

  17. Diversity of Type Ia Supernovae Imprinted in Chemical Abundances

    E-Print Network [OSTI]

    Tsujimoto, Takuji

    2012-01-01

    A time delay of Type Ia supernova (SN Ia) explosions hinders the imprint of their nucleosynthesis on stellar abundances. However, some occasional cases give birth to stars that avoid enrichment of their chemical compositions by massive stars and thereby exhibit a SN Ia-like elemental feature including a very low [Mg/Fe] (~-1). We highlight the elemental feature of Fe-group elements for two low-Mg/Fe objects detected in nearby galaxies, and propose the presence of a class of SNe Ia that yield the low abundance ratios of [Cr,Mn,Ni/Fe]. Our novel models of chemical evolution reveal that our proposed class of SNe Ia (slow SNe Ia) is associated with ones exploding on a long timescale after their stellar birth, and gives a significant impact on the chemical enrichment in the Large Magellanic Cloud (LMC). In the Galaxy, on the other hand, this effect is unseen due to the overwhelming enrichment by the major class of SNe Ia that explode promptly (prompt SNe Ia) and eject a large amount of Fe-group elements. This nice...

  18. A SEARCH FOR NEW CANDIDATE SUPER-CHANDRASEKHAR-MASS TYPE Ia SUPERNOVAE...

    Office of Scientific and Technical Information (OSTI)

    TYPE Ia SUPERNOVAE IN THE NEARBY SUPERNOVA FACTORY DATA SET We present optical photometry and spectroscopy of five Type Ia supernovae discovered by the Nearby Supernova...

  19. Direct numerical simulations of type Ia supernovae flames I: The landau-darrieus instability

    E-Print Network [OSTI]

    Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.

    2003-01-01

    Simulations of Type Ia Supernovae Flames I: The Landau-Subject headings: supernovae: general — white dwarfs —could occur in Type Ia supernovae (Niemeyer & Woosley 1997),

  20. DIVERSITY OF TYPE Ia SUPERNOVAE IMPRINTED IN CHEMICAL ABUNDANCES

    SciTech Connect (OSTI)

    Tsujimoto, Takuji [National Astronomical Observatory of Japan, Mitaka-shi, Tokyo 181-8588 (Japan); Shigeyama, Toshikazu, E-mail: taku.tsujimoto@nao.ac.jp [Research Center for the Early Universe, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2012-12-01

    A time delay of Type Ia supernova (SN Ia) explosions hinders the imprint of their nucleosynthesis on stellar abundances. However, some occasional cases give birth to stars that avoid enrichment of their chemical compositions by massive stars and thereby exhibit an SN-Ia-like elemental feature including a very low [Mg/Fe] ( Almost-Equal-To - 1). We highlight the elemental feature of Fe-group elements for two low-Mg/Fe objects detected in nearby galaxies, and propose the presence of a class of SNe Ia that yield the low abundance ratios of [Cr, Mn, Ni/Fe]. Our novel models of chemical evolution reveal that our proposed class of SNe Ia (slow SNe Ia) is associated with ones exploding on a long timescale after their stellar birth and give a significant impact on the chemical enrichment in the Large Magellanic Cloud (LMC). In the Galaxy, on the other hand, this effect is unseen due to the overwhelming enrichment by the major class of SNe Ia that explode promptly (prompt SNe Ia) and eject a large amount of Fe-group elements. This nicely explains the different [Cr, Mn, Ni/Fe] features between the two galaxies as well as the puzzling feature seen in the LMC stars exhibiting very low Ca but normal Mg abundances. Furthermore, the corresponding channel of slow SN Ia is exemplified by performing detailed nucleosynthesis calculations in the scheme of SNe Ia resulting from a 0.8 + 0.6 M{sub Sun} white dwarf merger.

  1. Sequence determinants of pri-miRNA processing

    E-Print Network [OSTI]

    Auyeung, Vincent C. (Vincent Churk-man)

    2012-01-01

    MicroRNAs (miRNAs) are short RNAs that regulate many processes in physiology and pathology by guiding the repression of target messenger RNAs. For classification purposes, miRNAs are defined as ~22 nt RNAs that are produced ...

  2. miR-132 and miR-212 are increased in pancreatic cancer and target the retinoblastoma tumor suppressor

    SciTech Connect (OSTI)

    Park, Jong-Kook [College of Pharmacy, Ohio State University, Columbus, OH 43210 (United States)] [College of Pharmacy, Ohio State University, Columbus, OH 43210 (United States); Henry, Jon C. [Department of Surgery, Ohio State University, Columbus, OH 43210 (United States)] [Department of Surgery, Ohio State University, Columbus, OH 43210 (United States); Jiang, Jinmai [College of Pharmacy, Ohio State University, Columbus, OH 43210 (United States)] [College of Pharmacy, Ohio State University, Columbus, OH 43210 (United States); Esau, Christine [Regulus Therapeutics, Carlsbad, CA (United States)] [Regulus Therapeutics, Carlsbad, CA (United States); Gusev, Yuriy [Lombardi Cancer Center, Georgetown University, Washington, DC (United States)] [Lombardi Cancer Center, Georgetown University, Washington, DC (United States); Lerner, Megan R. [Veterans Affairs Medical Center, Oklahoma City, OK (United States)] [Veterans Affairs Medical Center, Oklahoma City, OK (United States); Postier, Russell G. [Department of Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK (United States)] [Department of Surgery, University of Oklahoma Health Sciences Center, Oklahoma City, OK (United States); Brackett, Daniel J. [Veterans Affairs Medical Center, Oklahoma City, OK (United States)] [Veterans Affairs Medical Center, Oklahoma City, OK (United States); Schmittgen, Thomas D., E-mail: Schmittgen.2@osu.edu [College of Pharmacy, Ohio State University, Columbus, OH 43210 (United States)

    2011-03-25

    Research highlights: {yields} The expression of miR-132 and miR-212 are significantly increased in pancreatic cancer. {yields} miR-132 and miR-212 target the tumor suppressor pRb, resulting in enhanced proliferation. {yields} miR-132 and miR-212 expression is increased by a {beta}2 adrenergic receptor agonist, suggesting a novel mechanism for pancreatic cancer progression. -- Abstract: Numerous microRNAs (miRNAs) are reported as differentially expressed in cancer, however the consequence of miRNA deregulation in cancer is unknown for many miRNAs. We report that two miRNAs located on chromosome 17p13, miR-132 and miR-212, are over-expressed in pancreatic adenocarcinoma (PDAC) tissues. Both miRNAs are predicted to target the retinoblastoma tumor suppressor, Rb1. Validation of this interaction was confirmed by luciferase reporter assay and western blot in a pancreatic cancer cell line transfected with pre-miR-212 and pre-miR-132 oligos. Cell proliferation was enhanced in Panc-1 cells transfected with pre-miR-132/-212 oligos. Conversely, antisense oligos to miR-132/-212 reduced cell proliferation and caused a G{sub 2}/M cell cycle arrest. The mRNA of a number of E2F transcriptional targets were increased in cells over expressing miR-132/-212. Exposing Panc-1 cells to the {beta}2 adrenergic receptor agonist, terbutaline, increased the miR-132 and miR-212 expression by 2- to 4-fold. We report that over-expression of miR-132 and miR-212 result in reduced pRb protein in pancreatic cancer cells and that the increase in cell proliferation from over-expression of these miRNAs is likely due to increased expression of several E2F target genes. The {beta}2 adrenergic pathway may play an important role in this novel mechanism.

  3. Type Ia Supernovae: Progenitors and Evolution with Redshift

    E-Print Network [OSTI]

    Ken'ichi Nomoto; Hideyuki Umeda; Chiaki Kobayashi; Izumi Hachisu; Mariko Kato; Takuji Tsujimoto

    2000-03-09

    Relatively uniform light curves and spectral evolution of Type Ia supernovae (SNe Ia) have led to the use of SNe Ia as a ``standard candle'' to determine cosmological parameters. Whether a statistically significant value of the cosmological constant can be obtained depends on whether the peak luminosities of SNe Ia are sufficiently free from the effects of cosmic and galactic evolutions. Here we first review the single degenerate scenario for the Chandrasekhar mass white dwarf (WD) models of SNe Ia. We identify the progenitor's evolution and population with two channels: (1) the WD+RG (red-giant) and (2) the WD+MS (near main-sequence He-rich star) channels. In these channels, the strong wind from accreting WDs plays a key role, which yields important age and metallicity effects on the evolution. We then address the questions whether the nature of SNe Ia depends systematically on environmental properties such as metallicity and age of the progenitor system and whether significant evolutionary effects exist. We suggest that the variation of the carbon mass fraction $X$(C) in the C+O WD (or the variation of the initial WD mass) causes the diversity of the brightness of SNe Ia. This model can explain the observed dependences of SNe Ia brightness on the galaxy types and the distance from the galactic center. Finally, applying the metallicity effect on the evolution of SN Ia progenitors, we make a prediction of the cosmic supernova rate history as a composite of the supernova rates in different types of galaxies.

  4. Type Ia Supernova Progenitors, Environmental Effects, and Cosmic Supernova Rates

    E-Print Network [OSTI]

    Ken'ichi Nomoto; Hideyuki Umeda; Izumi Hachisu; Mariko Kato; Chiaki Kobayashi; Takuji Tsujimoto

    1999-07-27

    Relatively uniform light curves and spectral evolution of Type Ia supernovae (SNe Ia) have led to the use of SNe Ia as a ``standard candle'' to determine cosmological parameters, such as the Hubble constant, the density parameter, and the cosmological constant. Whether a statistically significant value of the cosmological constant can be obtained depends on whether the peak luminosities of SNe Ia are sufficiently free from the effects of cosmic and galactic evolutions. Here we first review the single degenerate scenario for the Chandrasekhar mass white dwarf (WD) models of SNe Ia. We identify the progenitor's evolution and population with two channels: (1) the WD+RG (red-giant) and (2) the WD+MS (near main-sequence He-rich star) channels. In these channels, the strong wind from accreting white dwarfs plays a key role, which yields important age and metallicity effects on the evolution. We then address the questions whether the nature of SNe Ia depends systematically on environmental properties such as metallicity and age of the progenitor system and whether significant evolutionary effects exist. We suggest that the variation of the carbon mass fraction $X$(C) in the C+O WD (or the variation of the initial WD mass) causes the diversity of the brightness of SNe Ia. This model can explain the observed dependence of SNe Ia brighness on the galaxy types. Finally, applying the metallicity effect on the evolution of SN Ia progenitors, we make a prediction of the cosmic supernova rate history as a composite of the supernova rates in different types of galaxies.

  5. “Nodal Gap” Induced by the Incommensurate Diagonal Spin Density Modulation in Underdoped High- <mi>Tmi>c> Superconductors

    SciTech Connect (OSTI)

    Zhou, Tao [Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China; Gao, Yi [Nanjing Normal University, Nanjing 210023, China; Zhu, Jian-Xin [Los Alamos National Laboratory, Los Alamos, NM 87545, USA

    2015-01-01

    Recently it was revealed that the whole Fermi surface is fully gapped for several families of underdoped cuprates. The existence of the finite energy gap along the<mi>d>-wave nodal lines (nodal gap) contrasts the common understanding of the<mi>d>-wave pairing symmetry, which challenges the present theories for the high-<mi>Tmi><mi>c>superconductors. Here we propose that the incommensurate diagonal spin-density-wave order can account for the above experimental observation. The Fermi surface and the local density of states are also studied. Our results are in good agreement with many important experiments in high-<mi>Tmi><mi>c>superconductors.

  6. From Convection to Explosion: End-to-End Simulation of Type Ia Supernovae

    E-Print Network [OSTI]

    Bell, John B.

    Ia supernova is the thermonuclear runaway and subsequent explosion of a white dwarf that is accreting

  7. Sweetspot: Near-infrared observations of 13 type Ia supernovae...

    Office of Scientific and Technical Information (OSTI)

    of 13 type Ia supernovae from a new NOAO survey probing the nearby smooth Hubble flow Citation Details In-Document Search Title: Sweetspot: Near-infrared observations of 13...

  8. Single-Degenerate Type Ia Supernovae Are Preferentially Overluminous

    E-Print Network [OSTI]

    Fisher, Robert

    2015-01-01

    Recent observational and theoretical progress has favored merging and helium-accreting sub-Chandrasekhar mass white dwarfs in the double-degenerate and the double-detonation channels, respectively, as the most promising progenitors of normal Type Ia supernovae (SNe Ia). Thus the fate of rapidly-accreting Chandrasekhar mass white dwarfs in the single-degenerate channel remains more mysterious then ever. In this paper, we clarify the nature of ignition in Chandrasekhar-mass single-degenerate SNe Ia by analytically deriving the existence of a characteristic length scale which establishes a transition from central ignitions to buoyancy-driven ignitions. Using this criterion, combined with data from three-dimensional simulations of convection and ignition, we demonstrate that the overwhelming majority of ignition events within Chandrasekhar-mass white dwarfs in the single-degenerate channel are buoyancy-driven, and consequently lack a vigorous deflagration phase. We thus infer that single-degenerate SNe Ia are gen...

  9. The Photometric Properties of Nearby Type Ia Supernovae

    E-Print Network [OSTI]

    Ganeshalingam, Mohan

    2012-01-01

    The Rise-Time Distribution of Nearby Type Ia Supernovae 3.1Highlight: The Physics of Supernovae, ed. W. Hillebrandt &1.1 Supernovae . . . . . . . . . . . . . . 1.1.1

  10. Type Ia Supernova Scenarios and the Hubble Sequence

    E-Print Network [OSTI]

    P. Ruiz-Lapuente; A. Burkert; R. Canal

    1995-05-19

    The dependence of the Type Ia supernova (SN Ia) rate on galaxy type is examined for three currently proposed scenarios: merging of a Chandrasekhar--mass CO white dwarf (WD) with a CO WD companion, explosion of a sub--Chandrasekhar mass CO WD induced by accretion of material from a He star companion, and explosion of a sub--Chandrasekhar CO WD in a symbiotic system. The variation of the SNe Ia rate and explosion characteristics with time is derived, and its correlation with parent population age and galaxy redshift is discussed. Among current scenarios, CO + He star systems should be absent from E galaxies. Explosion of CO WDs in symbiotic systems could account for the SNe Ia rate in these galaxies. The same might be true for the CO + CO WD scenario, depending on the value of the common envelope parameter. A testable prediction of the sub--Chandrasekhar WD model is that the average brightness and kinetic energy of the SN Ia events should increase with redshift for a given Hubble type. Also for this scenario, going along the Hubble sequence from E to Sc galaxies SNe Ia events should be brighter on average and should show larger mean velocities of the ejecta. The observational correlations strongly suggest that the characteristics of the SNe Ia explosion are linked to parent population age. The scenario in which WDs with masses below the Chandrasekhar mass explode appears the most promising one to explain the observed variation of the SN Ia rate with galaxy type together with the luminosity--expansion velocity trend.

  11. Dark Matter Admixed Type Ia Supernovae

    E-Print Network [OSTI]

    Leung, S -C; Lin, L -M

    2015-01-01

    We perform two-dimensional hydrodynamic simulations for the thermonuclear explosion of Chandrasekhar-mass white dwarfs with dark matter (DM) cores in Newtonian gravity. We include a 19-isotope nuclear reaction network and make use of the pure turbulent deflagration model as the explosion mechanism in our simulations. Our numerical results show that the general properties of the explosion depend quite sensitively on the mass of the DM core M$_{{\\rm DM}}$: a larger M$_{{\\rm DM}}$ generally leads to a weaker explosion and a lower mass of synthesized iron-peaked elements. In particular, the total mass of $^{56}$Ni produced can drop from about 0.3 to 0.03 $M_{\\odot}$ as M$_{{\\rm DM}}$ increases from 0.01 to 0.03 $M_{\\odot}$. We have also constructed the bolometric light curves obtained from our simulations and found that our results match well with the observational data of sub-luminous Type-Ia supernovae.

  12. Liver fibrosis causes downregulation of miRNA-150 and miRNA-194 in hepatic stellate cells, and their overexpression causes decreased stellate cell activation.

    E-Print Network [OSTI]

    Wu, Jian; Zern, M A

    2010-01-01

    Liver ?brosis causes downregulation of miRNA-150 and miRNA-and their overexpression causes decreased stellate cellJ, Zern MA. Liver ?brosis causes downregulation of miRNA-150

  13. Analytical Study of Hexapod miRNAs using Phylogenetic Methods

    E-Print Network [OSTI]

    Mishra, A K

    2012-01-01

    MicroRNAs (miRNAs) are a class of non-coding RNAs that regulate gene expression. Identification of total number of miRNAs even in completely sequenced organisms is still an open problem. However, researchers have been using techniques that can predict limited number of miRNA in an organism. In this paper, we have used homology based approach for comparative analysis of miRNA of hexapoda group .We have used Apis mellifera, Bombyx mori, Anopholes gambiae and Drosophila melanogaster miRNA datasets from miRBase repository. We have done pair wise as well as multiple alignments for the available miRNAs in the repository to identify and analyse conserved regions among related species. Unfortunately, to the best of our knowledge, miRNA related literature does not provide in depth analysis of hexapods. We have made an attempt to derive the commonality among the miRNAs and to identify the conserved regions which are still not available in miRNA repositories. The results are good approximation with a small number of mis...

  14. Simulations of Turbulent Thermonuclear Burning in Type Ia Supernovae

    E-Print Network [OSTI]

    W. Hillebrandt; M. Reinecke; W. Schmidt; F. K. Roepke; C. Travaglio; J. C. Niemeyer

    2004-05-11

    Type Ia supernovae have recently received considerable attention because it appears that they can be used as "standard candles" to measure cosmic distances out to billions of light years away from us. Observations of type Ia supernovae seem to indicate that we are living in a universe that started to accelerate its expansion when it was about half its present age. These conclusions rest primarily on phenomenological models which, however, lack proper theoretical understanding, mainly because the explosion process, initiated by thermonuclear fusion of carbon and oxygen into heavier elements, is difficult to simulate even on supercomputers. Here, we investigate a new way of modeling turbulent thermonuclear deflagration fronts in white dwarfs undergoing a type Ia supernova explosion. Our approach is based on a level set method which treats the front as a mathematical discontinuity and allows for full coupling between the front geometry and the flow field. New results of the method applied to the problem of type Ia supernovae are obtained. It is shown that in 2-D with high spatial resolution and a physically motivated subgrid scale model for the nuclear flames numerically "converged" results can be obtained, but for most initial conditions the stars do not explode. In contrast, simulations in 3-D, do give the desired explosions and many of their properties, such as the explosion energies, lightcurves and nucleosynthesis products, are in very good agreement with observed type Ia supernovae.

  15. BMPs Regulate the Oft Development via miRNAs 

    E-Print Network [OSTI]

    Bai, Yan

    2014-08-04

    c-Jun N-terminal Kinase LAP Latency Associated Peptide LLC Large Latent Complex LTBP Latent Tgf-? Binding Protein MFS Marfan Syndrome mi...

  16. ,"Detroit, MI Natural Gas Pipeline Imports From Canada (MMcf...

    U.S. Energy Information Administration (EIA) Indexed Site

    ,"Worksheet Name","Description"," Of Series","Frequency","Latest Data for" ,"Data 1","Detroit, MI Natural Gas Pipeline Imports From Canada (MMcf)",1,"Annual",2014 ,"Release...

  17. The Sequential Action of miR156 and miR172 Regulates Developmental Timing

    E-Print Network [OSTI]

    Weigel, Detlef

    Planck Institute for Developmental Biology, D-72076 Tu¨ bingen, Germany *Correspondence: spoethig@sas elegans (Moss, 2007; Rougvie, 2005) and plants (Ba¨ urle and Dean, 2006; Chuck and Hake, 2005; Poethig in Moss, 2007; Pasquinelli and Ruvkun, 2002; Rougvie, 2005). These were the first miRNAs to be discovered

  18. Strong Ultraviolet Pulse From a Newborn Type Ia Supernova

    E-Print Network [OSTI]

    Cao, Yi; Howell, D Andrew; Gal-Yam, Avishay; Kasliwal, Mansi M; Valenti, Stefano; Johansson, J; Amanullah, R; Goobar, A; Sollerman, J; Taddia, F; Horesh, Assaf; Sagiv, Ilan; Cenko, S Bradley; Nugent, Peter E; Arcavi, Iair; Surace, Jason; Wo?niak, P R; Moody, Daniela I; Rebbapragada, Umaa D; Bue, Brian D; Gehrels, Neil

    2015-01-01

    Type Ia supernovae are destructive explosions of carbon oxygen white dwarfs. Although they are used empirically to measure cosmological distances, the nature of their progenitors remains mysterious, One of the leading progenitor models, called the single degenerate channel, hypothesizes that a white dwarf accretes matter from a companion star and the resulting increase in its central pressure and temperature ignites thermonuclear explosion. Here we report observations of strong but declining ultraviolet emission from a Type Ia supernova within four days of its explosion. This emission is consistent with theoretical expectations of collision between material ejected by the supernova and a companion star, and therefore provides evidence that some Type Ia supernovae arise from the single degenerate channel.

  19. SPECTROSCOPY OF TYPE Ia SUPERNOVAE BY THE CARNEGIE SUPERNOVA PROJECT

    SciTech Connect (OSTI)

    Folatelli, Gaston [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), Todai Institutes for Advanced Study, the University of Tokyo, 277-8583 Kashiwa (Japan); Morrell, Nidia; Phillips, Mark M.; Hsiao, Eric; Campillay, Abdo; Contreras, Carlos; Castellon, Sergio; Roth, Miguel [Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile); Hamuy, Mario; Anderson, Joseph P. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Krzeminski, Wojtek [N. Copernicus Astronomical Center, ul. Bartycka 18, 00-716 Warszawa (Poland); Stritzinger, Maximilian [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Burns, Christopher R.; Freedman, Wendy L.; Madore, Barry F.; Murphy, David; Persson, S. E. [Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Prieto, Jose L. [Department of Astrophysical Sciences, Princeton University, 4 Ivy Ln., Princeton, NJ 08544 (United States); Suntzeff, Nicholas B.; Krisciunas, Kevin, E-mail: gaston.folatelli@ipmu.jp [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); and others

    2013-08-10

    This is the first release of optical spectroscopic data of low-redshift Type Ia supernovae (SNe Ia) by the Carnegie Supernova Project including 604 previously unpublished spectra of 93 SNe Ia. The observations cover a range of phases from 12 days before to over 150 days after the time of B-band maximum light. With the addition of 228 near-maximum spectra from the literature, we study the diversity among SNe Ia in a quantitative manner. For that purpose, spectroscopic parameters are employed such as expansion velocities from spectral line blueshifts and pseudo-equivalent widths (pW). The values of those parameters at maximum light are obtained for 78 objects, thus providing a characterization of SNe Ia that may help to improve our understanding of the properties of the exploding systems and the thermonuclear flame propagation. Two objects, namely, SNe 2005M and 2006is, stand out from the sample by showing peculiar Si II and S II velocities but otherwise standard velocities for the rest of the ions. We further study the correlations between spectroscopic and photometric parameters such as light-curve decline rate and color. In agreement with previous studies, we find that the pW of Si II absorption features are very good indicators of light-curve decline rate. Furthermore, we demonstrate that parameters such as pW2 (Si II 4130) and pW6 (Si II 5972) provide precise calibrations of the peak B-band luminosity with dispersions of Almost-Equal-To 0.15 mag. In the search for a secondary parameter in the calibration of peak luminosity for SNe Ia, we find a Almost-Equal-To 2{sigma}-3{sigma} correlation between B-band Hubble residuals and the velocity at maximum light of S II and Si II lines.

  20. Type Ia supernovae from merging white dwarfs. I. Prompt detonations

    SciTech Connect (OSTI)

    Moll, R.; Woosley, S. E. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Raskin, C.; Kasen, D. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2014-04-20

    Merging white dwarfs are a possible progenitor of Type Ia supernovae (SNe Ia). Numerical models suggest that a detonation might be initiated before the stars have coalesced to form a single compact object. Here we study such prompt detonations by means of numerical simulations, modeling the disruption and nucleosynthesis of the stars until the ejecta reach the coasting phase, and generating synthetic light curves and spectra. Three models are considered with primary masses 0.96 M {sub ?}, 1.06 M {sub ?}, and 1.20 M {sub ?}. Of these, the 0.96 M {sub ?} dwarf merging with a 0.81 M {sub ?} companion, with an {sup 56}Ni yield of 0.58 M {sub ?}, is the most promising candidate for reproducing common SNe Ia. The more massive mergers produce unusually luminous SNe Ia with peak luminosities approaching those attributed to 'super-Chandrasekhar' mass SNe Ia. While the synthetic light curves and spectra of some of the models resemble observed SNe Ia, the significant asymmetry of the ejecta leads to large orientation effects. The peak bolometric luminosity varies by more than a factor of two with the viewing angle, and the velocities of the spectral absorption features are lower when observed from angles where the light curve is brightest. The largest orientation effects are seen in the ultraviolet, where the flux varies by more than an order of magnitude. The set of three models roughly obeys a width-luminosity relation, with the brighter light curves declining more slowly in the B band. Spectral features due to unburned carbon from the secondary star are also seen in some cases.

  1. NEAR-ULTRAVIOLET PROPERTIES OF A LARGE SAMPLE OF TYPE Ia SUPERNOVAE...

    Office of Scientific and Technical Information (OSTI)

    SUPERNOVAE AS OBSERVED WITH THE Swift UVOT We present ultraviolet (UV) and optical photometry of 26 Type Ia supernovae (SNe Ia) observed from 2005 March to 2008 March with the...

  2. Spectral Observations and Analyses of Low-Redshift Type Ia Supernovae

    E-Print Network [OSTI]

    Silverman, Jeffrey Michael

    2011-01-01

    1.3.2 Thermonuclear Supernovae . . . . . . . . 1.4 Why WriteIa are the result of thermonuclear explosions of C/O whiteIa are the result of thermonuclear explosions of C/O white

  3. The Diversity of Variations in the Spectra of Type Ia Supernovae 

    E-Print Network [OSTI]

    Wagers, Andrew James

    2012-10-19

    Type Ia supernovae (SNe Ia) are currently the best probe of the expansion history of the universe. Their usefulness is due chiefly to their uniformity between supernovae (SNe). However, there are some slight variations amongst SNe that have yet...

  4. Feasibility of Measuring the Cosmological Constant [LAMBDA] and Mass Density [Omega] using Type Ia Supernovae

    E-Print Network [OSTI]

    Goobar, A.

    2008-01-01

    at z = 1. uncertainty for supernovae at z = 1. mR Adding theMass Density .Q Using Type Ia Supernovae A. Goobar and S.Density Q Using Type Ia Supernovae Ariel Goobar l and Saul

  5. UV Spectroscopy of Type Ia Supernovae at Low- and High-Redshift

    E-Print Network [OSTI]

    Nugent, Peter

    2005-01-01

    Spectroscopy of Type Ia Supernovae at Low- and High-RedshiftUV properties of Type Ia Supernovae. The low-redshift studyULDA Access Guide No. 6: Supernovae, The Netherlands: ESA

  6. Hubble Residuals of Nearby SN Ia Are Correlated with Host Galaxy...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Hubble Residuals of Nearby SN Ia Are Correlated with Host Galaxy Masses Citation Details In-Document Search Title: Hubble Residuals of Nearby SN Ia Are Correlated...

  7. Nearby Supernova Factory Observations of SN 2006D: On Sporadic Carbon Signatures in Early Type Ia Supernova Spectra

    E-Print Network [OSTI]

    2006-01-01

    with low volume-?lling factor. Subject headings: supernovae:general — supernovae: individual (SN 2006D)Introduction Type Ia supernovae (SNe Ia) make valuable

  8. Members of the miRNA-200 Family Regulate Olfactory Neurogenesis

    E-Print Network [OSTI]

    Choi, Philip S.

    MicroRNAs (miRNAs) are highly expressed in vertebrate neural tissues, but the contribution of specific miRNAs to the development and function of different neuronal populations is still largely unknown. We report that miRNAs ...

  9. Class IA Phosphoinositide 3-Kinase Modulates Basal Lymphocyte Motility in the Lymph Node1

    E-Print Network [OSTI]

    Parker, Ian

    Class IA Phosphoinositide 3-Kinase Modulates Basal Lymphocyte Motility in the Lymph Node1 Melanie P of the class IA PI3K regulatory subunits p85 and p85 also exhibited reduced velocities, with the magnitude show, for the first time, that class IA PI3Ks play an important role in regulating basal lymphocyte

  10. Identification of the companion stars of Type Ia supernovae

    E-Print Network [OSTI]

    R. Canal; J. Mendez; P. Ruiz-Lapuente

    2000-10-10

    The nature of the binary systems giving rise to Type Ia supernovae (SNeIa) remains an unsolved problem. In this {\\it Letter} we calculate, from the statistics of initial conditions (masses and binary separations), the mass, luminosity, and velocity distributions of the possible binary companions (main-sequence star, subgiant, red giant) following the explosion of the white dwarf which gives rise to the SNeIa. Those companions could be detected from either their proper or their radial motions, by means of high-precision astrometric and radial-velocity measurements in young, nearby supernova remnants. Peculiar velocities typically ranging from 100 to 450 km s$^{-1}$ should be expected, which places proper-motion measurements within reach of HST instruments and makes radial-velocity ones feasible with 2.5-4m class telescopes from the ground. Detections would solve the long-standing problem of which kind of binaries do produce SNeIa and clear up the way to accurate physical modeling of the explosions.

  11. Type Ia supernovae from exploding oxygen-neon white dwarfs

    E-Print Network [OSTI]

    Marquardt, Kai S; Ruiter, Ashley J; Seitenzahl, Ivo R; Ohlmann, Sebastian T; Kromer, Markus; Pakmor, Ruediger; Roepke, Friedrich K

    2015-01-01

    The progenitor problem of Type Ia supernovae (SNe Ia) is still unsolved. Most of these events are thought to be explosions of carbon-oxygen (CO) white dwarfs (WDs), but for many of the explosion scenarios, particularly those involving the externally triggered detonation of a sub-Chandrasekhar mass WD (sub-M Ch WD), there is also a possibility of having an oxygen-neon (ONe) WD as progenitor. We simulate detonations of ONe WDs and calculate synthetic observables from these models. The results are compared with detonations in CO WDs of similar mass and observational data of SNe Ia. We perform hydrodynamic explosion simulations of detonations in initially hydrostatic ONe WDs for a range of masses below the Chandrasekhar mass (M Ch), followed by detailed nucleosynthetic postprocessing with a 384-isotope nuclear reaction network. The results are used to calculate synthetic spectra and light curves, which are then compared with observations of SNe Ia. We also perform binary evolution calculations to determine the nu...

  12. Tracked Flame Simulation for Type Ia Yongmin Zhang1

    E-Print Network [OSTI]

    New York at Stoney Brook, State University of

    tracking of the ame front which is critically important to the accurate modeling of turbulent thermonuclear to be thermonu- clear explosions of white dwarfs. Type Ia supernovae are important sources of energy and chemical, and the strength and brightness of the burning are all determined by the speed of thermonuclear burning 12, 13

  13. Weld Surfacing Edited by Dr I.A. Bucklow

    E-Print Network [OSTI]

    Cambridge, University of

    V01.II Weld Surfacing Edited by Dr I.A. Bucklow ConferenceTechnicalDirector Organised by The Welding Institute in associationwith The Surface Engineering Society THE WELDING INSTITUTE #12;L becomesconfigurationally frozen at a temperature of about 1150°Cduring deposition by the manual-metal-arc welding technique

  14. A static universe is consistent with type Ia supernovae observations

    E-Print Network [OSTI]

    David F. Crawford

    2015-04-18

    This paper considers the hypothesis that the universe is static and demonstrates that type Ia supernova observations which appear to provide strong support for time dilation (and thus for an expanding universe) are equally consistent with a static universe. It is shown that a property of the standard calibration method means that regardless of what redshift dependence the measured light curve widths may have the calibrated widths always have little or no redshift dependence. An important consideration is the Phillips relation, a correlation between the peak-luminosity and the width of type Ia supernovae. Using the Phillips relation the analysis of a recent compilation of type Ia supernova observations is re-examined and it is shown that these observations are fully consistent with a static universe. It is also argued that the photometric redshift relation and spectroscopic ages are fully consistent with a static universe. As a separate but related issue it is shown that in the static model the density distribution of type Ia supernovae as a function of redshift agrees with the observations. All the evidence shows that the hypothesis is consistent with a static universe.

  15. The EqIA Publishing Template Impact Assessment Summary

    E-Print Network [OSTI]

    and aims of the policy, function or service. Resource Allocation for the period April 2010 to March 2013 3The EqIA Publishing Template Impact Assessment Summary 1. Name of policy, function or service. Who will benefit mainly from this policy, function or service? This plan provides for the sustainable

  16. Could there be a hole in type Ia supernovae?

    SciTech Connect (OSTI)

    Kasen, Daniel; Nugent, Peter; Thomas, R.C.; Wang, Lifan

    2004-04-23

    In the favored progenitor scenario, Type Ia supernovae (SNe Ia) arise from a white dwarf accreting material from a non-degenerate companion star. Soon after the white dwarf explodes, the ejected supernova material engulfs the companion star; two-dimensional hydrodynamical simulations by Marietta et al. (2001) show that, in the interaction, the companion star carves out a conical hole of opening angle 30-40 degrees in the supernova ejecta. In this paper we use multi-dimensional Monte Carlo radiative transfer calculations to explore the observable consequences of an ejecta-hole asymmetry. We calculate the variation of the spectrum, luminosity, and polarization with viewing angle for the aspherical supernova near maximum light. We find that the supernova looks normal from almost all viewing angles except when one looks almost directly down the hole. In the latter case, one sees into the deeper, hotter layers of ejecta. The supernova is relatively brighter and has a peculiar spectrum characterized by more highly ionized species, weaker absorption features, and lower absorption velocities. The spectrum viewed down the hole is comparable to the class of SN 1991T-like supernovae. We consider how the ejecta-hole asymmetry may explain the current spectropolarimetric observations of SNe Ia, and suggest a few observational signatures of the geometry. Finally, we discuss the variety currently seen in observed SNe Ia and how an ejecta-hole asymmetry may fit in as one of several possible sources of diversity.

  17. XRETRIEVE (request, i.a.) (iris.washington.edu)

    E-Print Network [OSTI]

    Laske, Gabi

    XRETRIEVE (request, i.a.) BDSN MEDNET IRIS DMC (iris.washington.edu) GEOSCOPE BREQ_FAST (request) email to BREQ_FAST@sob.iris.washington.edu interactive non-interactive customized pre-assembled customized pre-assembled www.iris.washington.edu (seismiquery/data sources) www.iris.washington.edu (FARM

  18. Thermonuclear supernova models, and observations of Type Ia supernovae

    E-Print Network [OSTI]

    E. Bravo; C. Badenes; D. Garcia-Senz

    2004-12-07

    In this paper, we review the present state of theoretical models of thermonuclear supernovae, and compare their predicitions with the constraints derived from observations of Type Ia supernovae. The diversity of explosion mechanisms usually found in one-dimensional simulations is a direct consequence of the impossibility to resolve the flame structure under the assumption of spherical symmetry. Spherically symmetric models have been successful in explaining many of the observational features of Type Ia supernovae, but they rely on two kinds of empirical models: one that describes the behaviour of the flame on the scales unresolved by the code, and another that takes account of the evolution of the flame shape. In contrast, three-dimensional simulations are able to compute the flame shape in a self-consistent way, but they still need a model for the propagation of the flame in the scales unresolved by the code. Furthermore, in three dimensions the number of degrees of freedom of the initial configuration of the white dwarf at runaway is much larger than in one dimension. Recent simulations have shown that the sensitivity of the explosion output to the initial conditions can be extremely large. New paradigms of thermonuclear supernovae have emerged from this situation, as the Pulsating Reverse Detonation. The resolution of all these issues must rely on the predictions of observational properties of the models, and their comparison with current Type Ia supernova data, including X-ray spectra of Type Ia supernova remnants.

  19. Cosmic Supernova Rate History and Type Ia Supernova Progenitors

    E-Print Network [OSTI]

    Chiaki Kobayashi; Ken'ichi Nomoto; Takuji Tsujimoto

    2001-02-14

    Adopting a single degenerate scenario for Type Ia supernova progenitors with the metallicity effect, we make a prediction of the cosmic supernova rate history as a composite of the supernova rates in spiral and elliptical galaxies, and compare with the recent observational data up to z ~ 0.55.

  20. Role for DNA methylation in the regulation of miR-200c and miR-141 expression in normal and cancer cells

    SciTech Connect (OSTI)

    Vrba, Lukas; Jensen, Taylor J.; Garbe, James C.; Heimark, Ronald L.; Cress, Anne E.; Dickinson, Sally; Stampfer, Martha R.; Futscher, Bernard W.

    2009-12-23

    BACKGROUND: The microRNA-200 family participates in the maintenance of an epithelial phenotype and loss of its expression can result in epithelial to mesenchymal transition (EMT). Furthermore, the loss of expression of miR-200 family members is linked to an aggressive cancer phenotype. Regulation of the miR-200 family expression in normal and cancer cells is not fully understood. METHODOLOGY/ PRINCIPAL FINDINGS: Epigenetic mechanisms participate in the control of miR-200c and miR-141 expression in both normal and cancer cells. A CpG island near the predicted mir-200c/mir-141 transcription start site shows a striking correlation between miR-200c and miR-141 expression and DNA methylation in both normal and cancer cells, as determined by MassARRAY technology. The CpG island is unmethylated in human miR-200/miR-141 expressing epithelial cells and in miR-200c/miR-141 positive tumor cells. The CpG island is heavily methylated in human miR-200c/miR-141 negative fibroblasts and miR-200c/miR-141 negative tumor cells. Mouse cells show a similar inverse correlation between DNA methylation and miR-200c expression. Enrichment of permissive histone modifications, H3 acetylation and H3K4 trimethylation, is seen in normal miR-200c/miR-141-positive epithelial cells, as determined by chromatin immunoprecipitation coupled to real-time PCR. In contrast, repressive H3K9 dimethylation marks are present in normal miR-200c/miR-141-negative fibroblasts and miR-200c/miR-141 negative cancer cells and the permissive histone modifications are absent. The epigenetic modifier drug, 5-aza-2'-deoxycytidine, reactivates miR-200c/miR-141 expression showing that epigenetic mechanisms play a functional role in their transcriptional control. CONCLUSIONS/ SIGNIFICANCE: We report that DNA methylation plays a role in the normal cell type-specific expression of miR-200c and miR-141 and this role appears evolutionarily conserved, since similar results were obtained in mouse. Aberrant DNA methylation of the miR-200c/141 CpG island is closely linked to their inappropriate silencing in cancer cells. Since the miR-200c cluster plays a significant role in EMT, our results suggest an important role for DNA methylation in the control of phenotypic conversions in normal cells.

  1. AlGaN/GaN-based power semiconductor switches

    E-Print Network [OSTI]

    Lu, Bin, Ph. D. Massachusetts Institute of Technology

    2013-01-01

    AlGaN/GaN-based high-electron-mobility transistors (HEMTs) have great potential for their use as high efficiency and high speed power semiconductor switches, thanks to their high breakdown electric field, mobility and ...

  2. Low-Metallicity Inhibition of Type Ia Supernovae and Galactic and Cosmic Chemical Evolution

    E-Print Network [OSTI]

    Chiaki Kobayashi; Takuji Tsujimoto; Ken'ich Nomoto; Izumi Hachisu; Mariko Kato

    1998-06-25

    We introduce a metallicity dependence of Type Ia supernova (SN Ia) rate into the Galactic and cosmic chemical evolution models. In our SN Ia progenitor scenario, the accreting white dwarf (WD) blows a strong wind to reach the Chandrasekhar mass limit. If the iron abundance of the progenitors is as low as [Fe/H] 1-2, SNe Ia can be found only in the environments where the timescale of metal enrichment is sufficiently short as in starburst galaxies and ellipticals. The low-metallicity inhibition of SNe Ia can shed new light on the following issues: 1) The limited metallicity range of the SN Ia progenitors would imply that ``evolution effects'' are relatively small for the use of high redshift SNe Ia to determine the cosmological parameters. 2) WDs of halo populations are poor producers of SNe Ia, so that the WD contribution to the halo mass is not constrained from the iron abundance in the halo. 3) The abundance patterns of globular clusters and field stars in the Galactic halo lack of SN Ia signatures in spite of their age difference of several Gyrs, which can be explained by the low-metallicity inhibition of SNe Ia. 4) It could also explain why the SN Ia contamination is not seen in the damped Ly\\alpha systems for over a wide range of redshift.

  3. An Analysis of Department of Defense Instruction 8500.2 'Information Assurance (IA) Implementation.'

    SciTech Connect (OSTI)

    Campbell, Philip LaRoche

    2012-01-01

    The Department of Defense (DoD) provides its standard for information assurance in its Instruction 8500.2, dated February 6, 2003. This Instruction lists 157 'IA Controls' for nine 'baseline IA levels.' Aside from distinguishing IA Controls that call for elevated levels of 'robustness' and grouping the IA Controls into eight 'subject areas' 8500.2 does not examine the nature of this set of controls, determining, for example, which controls do not vary in robustness, how this set of controls compares with other such sets, or even which controls are required for all nine baseline IA levels. This report analyzes (1) the IA Controls, (2) the subject areas, and (3) the Baseline IA levels. For example, this report notes that there are only 109 core IA Controls (which this report refers to as 'ICGs'), that 43 of these core IA Controls apply without variation to all nine baseline IA levels and that an additional 31 apply with variations. This report maps the IA Controls of 8500.2 to the controls in NIST 800-53 and ITGI's CoBIT. The result of this analysis and mapping, as shown in this report, serves as a companion to 8500.2. (An electronic spreadsheet accompanies this report.)

  4. miR-92a family and their target genes in tumorigenesis and metastasis

    SciTech Connect (OSTI)

    Li, Molin; Guan, Xingfang; Sun, Yuqiang; Mi, Jun; Shu, Xiaohong; Liu, Fang; Li, Chuangang

    2014-04-15

    The miR-92a family, including miR-25, miR-92a-1, miR-92a-2 and miR-363, arises from three different paralog clusters miR-17-92, miR-106a-363, and miR-106b-25 that are highly conservative in the process of evolution, and it was thought as a group of microRNAs (miRNAs) correlated with endothelial cells. Aberrant expression of miR-92a family was detected in multiple cancers, and the disturbance of miR-92a family was related with tumorigenesis and tumor development. In this review, the progress on the relationship between miR-92a family and their target genes and malignant tumors will be summarized. - Highlights: • Aberrant expression of miR-92a, miR-25 and miR-363 can be observed in many kinds of malignant tumors. • The expression of miR-92a family is regulated by LOH, epigenetic alteration, transcriptional factors such as SP1, MYC, E2F, wild-type p53 etc. • Roles of miR-92a family in tumorigenesis and development: promoting cell proliferation, invasion and metastasis, inhibiting cell apoptosis.

  5. Analytical Expressions For Light-Curves Of Ordinary And Superluminous Supernovae Type Ia

    E-Print Network [OSTI]

    Shlomo Dado; Arnon Dar

    2015-06-25

    Supernovae of type Ia (SNeIa) can be produced by the explosion of slowly-rotating carbon-oxygen white dwarfs whose mass increases beyond a critical value by mass accretion. Collision with circumstellar material during their photospheric and early nebular phase can enhance the bolometric luminosity of otherwise ordinary SNeIa to become superluminous. A few simplifying assumptions lead to a simple analytic master formula, which describes quite well the bolometric light-curves of ordinary SNeIa and supeluminous SNeIa in terms of few initial physical parameters. Other main properties of SNeIa, including the empirical 'brighter-slower' Phillips' relation that was used to standardize ordinary SNeIa as distance indicators and led to the discovery of the accelerating expansion of the universe, are reproduced

  6. Type Ia Supernova Spectral Line Ratios as LuminosityIndicators

    SciTech Connect (OSTI)

    Bongard, Sebastien; Baron, E.; Smadja, G.; Branch, David; Hauschildt, Peter H.

    2005-12-07

    Type Ia supernovae have played a crucial role in thediscovery of the dark energy, via the measurement of their light curvesand the determination of the peak brightness via fitting templates to theobserved lightcurve shape. Two spectroscopic indicators are also known tobe well correlated with peak luminosity. Since the spectroscopicluminosity indicators are obtained directly from observed spectra, theywill have different systematic errors than do measurements usingphotometry. Additionally, these spectroscopic indicators may be usefulfor studies of effects of evolution or age of the SNe~;Ia progenitorpopulation. We present several new variants of such spectroscopicindicators which are easy to automate and which minimize the effects ofnoise. We show that these spectroscopic indicators can be measured byproposed JDEM missions such as snap and JEDI.

  7. miR-143 Interferes with ERK5 Signaling, and Abrogates Prostate Cancer Progression in Mice

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    miR-143 Interferes with ERK5 Signaling, and Abrogates Prostate Cancer Progression in Mice Cyrielle-regulated kinase-5 (ERK5) activity. We show here that ERK5 is a miR-143 target in prostate cancer. Conclusions: mi, Apparailly F, Fernandez PL, et al. (2009) miR-143 Interferes with ERK5 Signaling, and Abrogates Prostate

  8. Power-law cosmology, SN Ia, and BAO

    SciTech Connect (OSTI)

    Dolgov, Aleksander; Halenka, Vitali; Tkachev, Igor E-mail: vithal@umich.edu

    2014-10-01

    We revise observational constraints on the class of models of modified gravity which at low redshifts lead to a power-law cosmology. To this end we use available public data on Supernova Ia and on baryon acoustic oscillations. We show that the expansion regime a(t) ? t{sup ?} with ? close to 3/2 in a spatially flat universe is a good fit to these data.

  9. Signatures of a companion star in type Ia supernovae

    SciTech Connect (OSTI)

    Maeda, Keiichi [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Kutsuna, Masamichi; Shigeyama, Toshikazu, E-mail: keiichi.maeda@kusastro.kyoto-u.ac.jp [Research Center for the Early Universe, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2014-10-10

    Although type Ia supernovae (SNe Ia) have been used as precise cosmological distance indicators, their progenitor systems remain unresolved. One of the key questions is whether there is a nondegenerate companion star at the time of a thermonuclear explosion of a white dwarf. In this paper, we investigate whether an interaction between the SN ejecta and the companion star may result in observable footprints around the maximum brightness and thereafter, by performing multidimensional radiation transfer simulations based on hydrodynamic simulations of the interaction. We find that such systems result in variations in various observational characteristics due to different viewing directions, and the predicted behaviors (redder and fainter for the companion direction) are the opposite of what were suggested by the previous study. The variations are generally modest and within observed scatters. However, the model predicts trends between some observables different from those observationally derived, so a large sample of SNe Ia with small calibration errors may be used to constrain the existence of such a companion star. The variations in different colors in optical band passes can be mimicked by external extinctions, so such an effect could be a source of scatter in the peak luminosity and derived distance. After the peak, hydrogen-rich materials expelled from the companion will manifest themselves in hydrogen lines, but H? is extremely difficult to identify. Alternatively, we find that P{sub ?} in postmaximum near-infrared spectra can potentially provide a powerful diagnostic.

  10. CARBON DEFLAGRATION IN TYPE Ia SUPERNOVA. I. CENTRALLY IGNITED MODELS

    SciTech Connect (OSTI)

    Ma, H.; Woosley, S. E.; Malone, C. M. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Almgren, A.; Bell, J. [Center for Computational Sciences and Engineering, Lawrence Berkeley National Lab, Berkeley, CA 94720 (United States)

    2013-07-01

    A leading model for Type Ia supernovae (SNe Ia) begins with a white dwarf near the Chandrasekhar mass that ignites a degenerate thermonuclear runaway close to its center and explodes. In a series of papers, we shall explore the consequences of ignition at several locations within such dwarfs. Here we assume central ignition, which has been explored before, but is worth revisiting, if only to validate those previous studies and to further elucidate the relevant physics for future work. A perturbed sphere of hot iron ash with a radius of {approx}100 km is initialized at the middle of the star. The subsequent explosion is followed in several simulations using a thickened flame model in which the flame speed is either fixed-within the range expected from turbulent combustion-or based on the local turbulent intensity. Global results, including the explosion energy and bulk nucleosynthesis (e.g., {sup 56}Ni of 0.48-0.56 M{sub Sun }) turn out to be insensitive to this speed. In all completed runs, the energy released by the nuclear burning is adequate to unbind the star, but not enough to give the energy and brightness of typical SNe Ia. As found previously, the chemical stratification observed in typical events is not reproduced. These models produce a large amount of unburned carbon and oxygen in central low velocity regions, which is inconsistent with spectroscopic observations, and the intermediate mass elements and iron group elements are strongly mixed during the explosion.

  11. NuMI Target Station AHIPA09 10/19/09

    E-Print Network [OSTI]

    McDonald, Kirk

    MI Target Station AHIPA09 10/19/09 Jim Hylen/FNAL Page 11Remote 5-axis lift table Numi target+baffle on liftNuMI Target Station AHIPA09 10/19/09 Jim Hylen/FNAL Page 1 Target Station Infrastructure: The Nu slide overview of NuMI #12;NuMI Target Station AHIPA09 10/19/09 Jim Hylen/FNAL Page 2 NuMI produces

  12. Regulation of Synaptic Structure and Function by FMRP-Associated MicroRNAs miR-125b and miR-132

    E-Print Network [OSTI]

    Edbauer, Dieter

    MicroRNAs (miRNAs) are noncoding RNAs that suppress translation of specific mRNAs. The miRNA machinery interacts with fragile X mental retardation protein (FMRP), which functions as translational repressor. We show that ...

  13. Gravitational Wave Emission from the Single-Degenerate Channel of Type Ia Supernovae

    E-Print Network [OSTI]

    David Falta; Robert T. Fisher; Gaurav Khanna

    2011-05-28

    The thermonuclear explosion of a C/O white dwarf as a Type Ia supernova (SN Ia) generates a kinetic energy comparable to that released by a massive star during a SN II event. Current observations and theoretical models have established that SNe Ia are asymmetric, and therefore--like SNe II--potential sources of gravitational wave (GW) radiation. We perform the first detailed calculations of the GW emission for a SN Ia of any type within the single-degenerate channel. The gravitationally-confined detonation (GCD) mechanism predicts a strongly-polarized GW burst in the frequency band around 1 Hz. Third-generation spaceborne GW observatories currently in planning may be able to detect this predicted signal from SNe Ia at distances up to 1 Mpc. If observable, GWs may offer a direct probe into the first few seconds of the SNe Ia detonation.

  14. Teor'ia de Grupos y Mec'anica Qu'antica Luis A. Seco

    E-Print Network [OSTI]

    Seco, Luis A.

    Teor'ia de Grupos y Mec'anica Qu'antica Luis A. Seco Universidad de Toronto. Notas del curso; Teor'ia de Grupos y Mec'anica Cu'antica, L. Seco. U.I.M.P. La Coru~na, 27 Junio -- 1 Julio, 1994. Preliminares Este curso recoge diversos temas que se encuentran a caballo entre la teor'ia de grupos y la mec

  15. A Multi-scale Study of Inorganic Aqueous Solution (IAS) for Advanced Heat Pipe Applications

    E-Print Network [OSTI]

    Amouzegar Ashtiani, Ladan

    2015-01-01

    Surfaces to Wetting by Water," Industrial & Engineeringheterogenous porous media," WATER RESOURCES RESEARCH, vol.Exp. 1 Exp. 2 Exp. 3 Exp. 4 water water IAS#0 working fluid

  16. THE HYBRID CONe WD + He STAR SCENARIO FOR THE PROGENITORS OF TYPE Ia SUPERNOVAE

    SciTech Connect (OSTI)

    Wang, B.; Meng, X.; Liu, D.-D.; Han, Z. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Liu, Z.-W., E-mail: wangbo@ynao.ac.cn [Argelander-Institut für Astronomie, Auf dem Hügel 71, D-53121, Bonn (Germany)

    2014-10-20

    Hybrid CONe white dwarfs (WDs) have been suggested to be possible progenitors of type Ia supernovae (SNe Ia). In this Letter, we systematically studied the hybrid CONe WD + He star scenario for the progenitors of SNe Ia, in which a hybrid CONe WD increases its mass to the Chandrasekhar mass limit by accreting He-rich material from a non-degenerate He star. We obtained the SN Ia birthrates and delay times for this scenario using to a series of detailed binary population synthesis simulations. The SN Ia birthrates for this scenario are ?0.033-0.539 × 10{sup –3} yr{sup –1}, which roughly accounts for 1%-18% of all SNe Ia. The estimated delay times are ?28 Myr-178 Myr, which makes these the youngest SNe Ia predicted by any progenitor model so far. We suggest that SNe Ia from this scenario may provide an alternative explanation for type Iax SNe. We also presented some properties of the donors at the point when the WDs reach the Chandrasekhar mass. These properties may be a good starting point for investigating the surviving companions of SNe Ia and for constraining the progenitor scenario studied in this work.

  17. Multi-layered Spectral Formation in SNe Ia Around Maximum Light

    E-Print Network [OSTI]

    Bongard, Sebastien

    2008-01-01

    stars: atmospheres — supernovae DISCLAIMER This document wasIntroduction Type Ia supernovæ have been used as “spanning the “normal” supernovæ blue magnitudes. Single Ion

  18. High-Redshift Type Ia Supernova Rates in Galaxy Cluster and Field Environments

    E-Print Network [OSTI]

    Barbary, Kyle Harris

    2011-01-01

    29 Candidates classified as supernovae . . . . . . . .1.1 Type Ia Supernovae as Standard Candles . . . . . . . .4.2.3 Supernovae . . . . . . . . . . . . . . . . 4.2.4

  19. Direct numerical simulations of type Ia supernovae flames II: The rayleigh-taylor instability

    E-Print Network [OSTI]

    Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.

    2004-01-01

    Weaver, T. A. 1994, in Supernovae, Les Houches, Session LIV,Simulations of Type Ia Supernovae Flames II: The Rayleigh-Subject headings: supernovae: general — white dwarfs —

  20. Timescale stretch parameterization of Type Ia supernova B-band light curves

    E-Print Network [OSTI]

    2001-01-01

    the light curve of Type Ia supernovae discovered by theof the high-redshift supernovae. This work was supported inobjects. Subject headings: supernovae: general – cosmology:

  1. The Carnegie Supernova Project: Intrinsic colors of type Ia supernovae

    SciTech Connect (OSTI)

    Burns, Christopher R.; Persson, S. E.; Freedman, Wendy L.; Madore, Barry F. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Stritzinger, Maximilian; Contreras, Carlos [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Phillips, M. M.; Hsiao, E. Y.; Boldt, Luis; Campillay, Abdo; Castellón, Sergio; Morrell, Nidia; Salgado, Francisco [Carnegie Institution of Washington, Las Campanas Observatory, Colina El Pino, Casilla 601 (Chile); Folatelli, Gaston [Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study, the University of Tokyo, 277-8583 Kashiwa (Japan); Suntzeff, Nicholas B. [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, Department of Physics and Astronomy, College Station, TX 77843 (United States)

    2014-07-01

    We present an updated analysis of the intrinsic colors of Type Ia supernova (SNe Ia) using the latest data release of the Carnegie Supernova Project. We introduce a new light-curve parameter very similar to stretch that is better suited for fast-declining events, and find that these peculiar types can be seen as extensions to the population of 'normal' SNe Ia. With a larger number of objects, an updated fit to the Lira relation is presented along with evidence for a dependence on the late-time slope of the B – V light-curves with stretch and color. Using the full wavelength range from u to H band, we place constraints on the reddening law for the sample as a whole and also for individual events/hosts based solely on the observed colors. The photometric data continue to favor low values of R{sub V} , though with large variations from event to event, indicating an intrinsic distribution. We confirm the findings of other groups that there appears to be a correlation between the derived reddening law, R{sub V} , and the color excess, E(B – V), such that larger E(B – V) tends to favor lower R{sub V} . The intrinsic u-band colors show a relatively large scatter that cannot be explained by variations in R{sub V} or by the Goobar power-law for circumstellar dust, but rather is correlated with spectroscopic features of the supernova and is therefore likely due to metallicity effects.

  2. Marginal evidence for cosmic acceleration from Type Ia supernovae

    E-Print Network [OSTI]

    Jeppe Trøst Nielsen; Alberto Guffanti; Subir Sarkar

    2015-06-09

    The "standard" model of cosmology is founded on the basis that the expansion rate of the universe is accelerating at present --- as was inferred originally from the Hubble diagram of Type Ia supernovae. There exists now a much bigger database of supernovae so we can perform rigorous statistical tests to check whether these "standardisable candles" indeed indicate cosmic acceleration. Taking account of the empirical procedure by which corrections are made to their absolute magnitudes to allow for the varying shape of the light curve and extinction by dust, we find, rather surprisingly, that the data are still quite consistent with a constant rate of expansion.

  3. Marginal evidence for cosmic acceleration from Type Ia supernovae

    E-Print Network [OSTI]

    Nielsen, Jeppe Trøst; Sarkar, Subir

    2015-01-01

    The `standard' model of cosmology is founded on the basis that the expansion rate of the universe is accelerating at present --- as was inferred originally from the Hubble diagram of Type Ia supernovae. There exists now a much bigger database of supernovae so we can perform rigorous statistical tests to check whether these `standardisable candles' indeed indicate cosmic acceleration. Taking account of the empirical procedure by which corrections are made to their absolute magnitudes to allow for the varying shape of the light curve and extinction by dust, we find, rather surprisingly, that the data are still quite consistent with a constant rate of expansion.

  4. Grouping normal type Ia supernovae by UV to optical color differences

    SciTech Connect (OSTI)

    Milne, Peter A.; Brown, Peter J.; Roming, Peter W. A.; Bufano, Filomena; Gehrels, Neil

    2013-12-10

    Observations of many Type Ia supernovae (SNe Ia) for multiple epochs per object with the Swift Ultraviolet Optical Telescope instrument have revealed that there exists order to the differences in the UV-optical colors of optically normal supernovae (SNe). We examine UV-optical color curves for 23 SNe Ia, dividing the SNe into four groups, and find that roughly one-third of 'NUV-blue' SNe Ia have bluer UV-optical colors than the larger 'NUV-red' group. Two minor groups are recognized, 'MUV-blue' and 'irregular' SNe Ia. While we conclude that the latter group is a subset of the NUV-red group, containing the SNe with the broadest optical peaks, we conclude that the 'MUV-blue' group is a distinct group. Separating into the groups and accounting for the time evolution of the UV-optical colors lowers the scatter in two NUV-optical colors (e.g., u – v and uvw1 – v) to the level of the scatter in b – v. This finding is promising for extending the cosmological utilization of SNe Ia into the NUV. We generate spectrophotometry of 33 SNe Ia and determine the correct grouping for each. We argue that there is a fundamental spectral difference in the 2900-3500 Å wavelength range, a region suggested to be dominated by absorption from iron-peak elements. The NUV-blue SNe Ia feature less absorption than the NUV-red SNe Ia. We show that all NUV-blue SNe Ia in this sample also show evidence of unburned carbon in optical spectra, whereas only one NUV-red SN Ia features that absorption line. Every NUV-blue event also exhibits a low gradient of the Si II ?6355 absorption feature. Many NUV-red events also exhibit a low gradient, perhaps suggestive that NUV-blue events are a subset of the larger low-velocity gradient group.

  5. miRNA-205 affects infiltration and metastasis of breast cancer

    SciTech Connect (OSTI)

    Wang, Zhouquan; Department of Tumor, SenGong Hospital of Shaanxi, Xi’an 710300 ; Liao, Hehe; Deng, Zhiping; Yang, Po; Du, Ning; Zhanng, Yunfeng; Ren, Hong

    2013-11-08

    Highlights: •We detected expression of miR-205 in breast cancer cell lines and tissue samples. •We suggest miR-205 is downregulated in human breast cancer tissues and MCF7 cells. •We suggest the lower expression of miR-205 play a role in breast cancer onset. •These data suggest that miR-205 directly targets HER3 in human breast cancer. -- Abstract: Background: An increasing number of studies have shown that miRNAs are commonly deregulated in human malignancies, but little is known about the function of miRNA-205 (miR-205) in human breast cancer. The present study investigated the influence of miR-205 on breast cancer malignancy. Methods: The expression level of miR-205 in the MCF7 breast cancer cell line was determined by quantitative (q)RT-PCR. We then analyzed the expression of miR-205 in breast cancer and paired non-tumor tissues. Finally, the roles of miR-205 in regulating tumor proliferation, apoptosis, migration, and target gene expression were studied by MTT assay, flow cytometry, qRT-PCR, Western blotting and luciferase assay. Results: miR-205 was downregulated in breast cancer cells or tissues compared with normal breast cell lines or non-tumor tissues. Overexpression of miR-205 reduced the growth and colony-formation capacity of MCF7 cells by inducing apoptosis. Overexpression of miR-205 inhibited MCF7 cell migration and invasiveness. By bioinformation analysis, miR-205 was predicted to bind to the 3? untranslated regions of human epidermal growth factor receptor (HER)3 mRNA, and upregulation of miR-205 reduced HER3 protein expression. Conclusion: miR-205 is a tumor suppressor in human breast cancer by post-transcriptional inhibition of HER3 expression.

  6. miR-132, an experience-dependent microRNA, is essential for visual cortex plasticity

    E-Print Network [OSTI]

    Mellios, Nikolaos

    Using quantitative analyses, we identified microRNAs (miRNAs) that were abundantly expressed in visual cortex and that responded to dark rearing and/or monocular deprivation. The most substantially altered miRNA, miR-132, ...

  7. THE BIRTH RATE OF SNe Ia FROM HYBRID CONe WHITE DWARFS

    SciTech Connect (OSTI)

    Meng, Xiangcun [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Podsiadlowski, Philipp, E-mail: xiangcunmeng@ynao.ac.cn [Department of Astronomy, Oxford University, Oxford OX1 3RH (United Kingdom)

    2014-07-10

    Considering the uncertainties of the C-burning rate (CBR) and the treatment of convective boundaries, Chen et al. found that there is a regime where it is possible to form hybrid CONe white dwarfs (WDs), i.e., ONe WDs with carbon-rich cores. As these hybrid WDs can be as massive as 1.30 M {sub ?}, not much mass needs to be accreted for these objects to reach the Chandrasekhar limit and to explode as Type Ia supernovae (SNe Ia). We have investigated their contribution to the overall SN Ia birth rate and found that such SNe Ia tend to be relatively young with typical time delays between 0.1 and 1 Gyr, where some may be as young as 30 Myr. SNe Ia from hybrid CONe WDs may contribute several percent to all SNe Ia, depending on the common-envelope ejection efficiency and the CBR. We suggest that these SNe Ia may produce part of the 2002cx-like SN Ia class.

  8. Bolometric Light Curves of Type Ia Supernovae G. Contardo 1;2 , B. Leibundgut 1

    E-Print Network [OSTI]

    Leibundgut, Bruno

    Bolometric Light Curves of Type Ia Supernovae G. Contardo 1;2 , B. Leibundgut 1 1 European Southern, Karl­Schwarzschild­Straße 1, D­85748 Garch­ ing, Germany 1.1 Light Curves of Type Ia Supernovae Substantial information about the processes in supernovae is contained in their light curves. They track

  9. Measurement of Omega_m, Omega_Lambda from a blind analysis of Type Ia supernovae with CMAGIC: Using color information to verify the acceleration of the Universe

    E-Print Network [OSTI]

    2006-01-01

    analysis of Type Ia supernovae with CMAGIC: Using colorof 21 high redshift supernovae using a new technique (lightcurves of Type Ia supernovae, ?rst introduced in Wang

  10. Molecular Cell Loss of miR-200 Inhibition of Suz12 Leads to

    E-Print Network [OSTI]

    In an inducible oncogenesis model, the miR-200 family is inhibited during CSC formation but not trans- formation

  11. Discovery of miRNA-regulated processes in mammalian development

    E-Print Network [OSTI]

    Young, Amanda Garfinkel

    2010-01-01

    The genomes of plants and animals encode hundreds of non-coding ~22nt RNAs termed "microRNAs" (miRNAs). These RNAs guide the sequence-specific inhibition of translation and destabilization of mRNA targets through short ...

  12. Polarization-engineered GaN/InGaN/GaN tunnel diodes

    SciTech Connect (OSTI)

    Krishnamoorthy, Sriram; Nath, Digbijoy N.; Akyol, Fatih; Park, Pil Sung; Esposto, Michele; Rajan, Siddharth [Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States)

    2010-11-15

    We report on the design and demonstration of polarization-engineered GaN/InGaN/GaN tunnel junction diodes with high current density and low tunneling turn-on voltage. Wentzel-Kramers-Brillouin calculations were used to model and design tunnel junctions with narrow band gap InGaN-based barrier layers. N-polar p-GaN/In{sub 0.33}Ga{sub 0.67}N/n-GaN heterostructure tunnel diodes were grown using molecular beam epitaxy. Efficient interband tunneling was achieved close to zero bias with a high current density of 118 A/cm{sup 2} at a reverse bias of 1 V, reaching a maximum current density up to 9.2 kA/cm{sup 2}. These results represent the highest current density reported in III-nitride tunnel junctions and demonstrate the potential of III-nitride tunnel devices for a broad range of optoelectronic and electronic applications.

  13. Radiosensitizing Effects of Ectopic miR-101 on Non-Small-Cell Lung Cancer Cells Depend on the Endogenous miR-101 Level

    SciTech Connect (OSTI)

    Chen, Susie; Wang Hongyan; Ng, Wooi Loon; Curran, Walter J.; Wang Ya

    2011-12-01

    Purpose: Previously, we showed that ectopic miR-101 could sensitize human tumor cells to radiation by targeting ATM and DNA-PK catalytic subunit (DNA-PKcs) to inhibit DNA repair, as the endogenous miR-101 levels are low in tumors in general. However, the heterogeneity of human cancers may result in an exception. The purpose of this study was to test the hypothesis that a few tumor cell lines with a high level of endogenous miR-101 would prove less response to ectopic miR-101. Methods and Materials: Fourteeen non-small-cell lung cancer (NSCLC) cell lines and one immortalized non-malignant lung epithelial cell line (NL20) were used for comparing endogenous miR-101 levels by real-time reverse transcription-polymerase chain reaction. Based on the different miR-101 levels, four cell lines with different miR-101 levels were chosen for transfection with a green fluorescent protein-lentiviral plasmid encoding miR-101. The target protein levels were measured by using Western blotting. The radiosensitizing effects of ectopic miR-101 on these NSCLC cell lines were determined by a clonogenic assay and xenograft mouse model. Results: The endogenous miR-101 level was similar or lower in 13 NSCLC cell lines but was 11-fold higher in one cell line (H157) than in NL20 cells. Although ectopic miR-101 efficiently decreased the ATM and DNA-PKcs levels and increased the radiosensitization level in H1299, H1975, and A549 cells, it did not change the levels of the miR-101 targets or radiosensitivity in H157 cells. Similar results were observed in xenograft mice. Conclusions: A small number of NSCLC cell lines could have a high level of endogenous miR-101. The ectopic miR-101 was able to radiosensitize most NSCLC cells, except for the NSCLC cell lines that had a much higher endogenous miR-101 level. These results suggest that when we choose one miRNA as a therapeutic tool, the endogenous level of the miRNA in each tumor should be considered.

  14. Supernova progenitor constraints from circumstellar interaction: Type Ia

    E-Print Network [OSTI]

    Peter Lundqvist; Robert J. Cumming

    1996-10-03

    Searching for the presence of a circumstellar medium is a direct observational way to discriminate between different types of progenitor systems for Type Ia supernovae. We have modeled whether such gas may give rise to detectable emission, especially in H-alpha, and compare the models with observations of SN 1994D. We obtain a mass loss rate less than about 2.5 10^{-5} solar masses per year for a wind speed of 10 km/s. We find that X-ray observations in the range 5-10 keV, e.g., with AXAF, provide the most useful limits on the mass loss, while high-resolution optical spectroscopy offers the only direct way of identifying circumstellar hydrogen.

  15. Random Walker Ranking for NCAA Division I-A Football

    E-Print Network [OSTI]

    Callaghan, T; Mucha, P J; Callaghan, Thomas; Porter, Mason A.; Mucha, Peter J.

    2003-01-01

    We develop a one-parameter family of ranking systems for NCAA Division I-A football teams based on a collection of voters, each with a single vote, executing independent random walks on a network defined by the teams (vertices) and the games played (edges). The virtue of this class of ranking systems lies in the simplicity of its explanation. We discuss the statistical properties of the randomly walking voters and relate them to the community structure of the underlying network. We compare the results of these rankings for recent seasons with Bowl Championship Series standings and component rankings. To better understand this ranking system, we also examine the asymptotic behaviors of the aggregate of walkers. Finally, we consider possible generalizations to this ranking algorithm.

  16. No evidence for bulk velocity from type Ia supernovae

    E-Print Network [OSTI]

    Huterer, Dragan; Schmidt, Fabian

    2015-01-01

    We revisit the effect of peculiar velocities on low-redshift type Ia supernovae. Velocities introduce an additional guaranteed source of correlations between supernova magnitudes that should be considered in all analyses of nearby supernova samples but has largely been neglected in the past. Applying a likelihood analysis to the latest compilation of nearby supernovae, we find no evidence for the presence of these correlations, although, given the significant noise, the data is also consistent with the correlations predicted for the standard LCDM model. We then consider the dipolar component of the velocity correlations - the frequently studied "bulk velocity" - and explicitly demonstrate that including the velocity correlations in the data covariance matrix is crucial for drawing correct and unambiguous conclusions about the bulk flow. In particular, current supernova data is consistent with no excess bulk flow on top of what is expected in LCDM and effectively captured by the covariance. We further clarify ...

  17. On Measuring the Metallicity of Supernovae Type Ia Progenitors

    E-Print Network [OSTI]

    Miles, Broxton J; Townsley, Dean M; Timmes, F X; Jackson, Aaron P; Calder, Alan C; Brown, Edward F

    2015-01-01

    In Type Ia Supernovae (\\sneia), the relative abundances of chemical elements are affected by the neutron excess in the composition of the progenitor white dwarf. Since these products leave signatures in the spectra near maximum light, spectral features may be used to constrain the composition of the progenitor. We calculate the nucleosynthetic yields for three \\snia simulations for a wide range of progenitor metallicities, and calculate synthetic light curves and spectra to explore correlations between progenitor metallicity and the strength of spectral features. We use two 2D simulations of the deflagration-detonation-transition scenario with different $^{56}$Ni yields and the W7 simulation to control for differences between explosion models and total yields. While the overall yields of intermediate mass elements (16 $<$ A $\\leq$ 40) differ between the three cases, trends in the yields are similar. With increasing metallicity, $^{28}$Si yields remain nearly constant, $^{40}$Ca yields decline, and Ti and $...

  18. A new hydrodynamics code for Type Ia Supernovae

    E-Print Network [OSTI]

    Leung, S -C; Lin, L -M

    2015-01-01

    A two-dimensional hydrodynamics code for Type Ia supernovae (SNIa) simulations is presented. The code includes a fifth-order shock-capturing scheme WENO, detailed nuclear reaction network, flame-capturing scheme and sub-grid turbulence. For post-processing we have developed a tracer particle scheme to record the thermodynamical history of the fluid elements. We also present a one-dimensional radiative transfer code for computing observational signals. The code solves the Lagrangian hydrodynamics and moment-integrated radiative transfer equations. A local ionization scheme and composition dependent opacity are included. Various verification tests are presented, including standard benchmark tests in one and two dimensions. SNIa models using the pure turbulent deflagration model and the delayed-detonation transition model are studied. The results are consistent with those in the literature. We compute the detailed chemical evolution using the tracer particles' histories, and we construct corresponding bolometric...

  19. Type Ia supernova Hubble residuals and host-galaxy properties

    SciTech Connect (OSTI)

    Kim, A. G.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Fleury, M.; Guy, J. [Laboratoire de Physique Nucléaire et des Hautes Énergies, Université Pierre et Marie Curie Paris 6, Université Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Baltay, C. [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States); Buton, C.; Feindt, U.; Greskovic, P.; Kowalski, M. [Physikalisches Institut, Universität Bonn, Nußallee 12, D-53115 Bonn (Germany); Childress, M. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Chotard, N.; Copin, Y.; Gangler, E. [Université de Lyon, F-69622 Lyon (France); Université de Lyon 1, Villeurbanne (France); CNRS/IN2P3, Institut de Physique Nucléaire de Lyon (France); and others

    2014-03-20

    Kim et al. introduced a new methodology for determining peak-brightness absolute magnitudes of type Ia supernovae from multi-band light curves. We examine the relation between their parameterization of light curves and Hubble residuals, based on photometry synthesized from the Nearby Supernova Factory spectrophotometric time series, with global host-galaxy properties. The K13 Hubble residual step with host mass is 0.013 ± 0.031 mag for a supernova subsample with data coverage corresponding to the K13 training; at <<1?, the step is not significant and lower than previous measurements. Relaxing the data coverage requirement of the Hubble residual step with the host mass is 0.045 ± 0.026 mag for the larger sample; a calculation using the modes of the distributions, less sensitive to outliers, yields a step of 0.019 mag. The analysis of this article uses K13 inferred luminosities, as distinguished from previous works that use magnitude corrections as a function of SALT2 color and stretch parameters: steps at >2? significance are found in SALT2 Hubble residuals in samples split by the values of their K13 x(1) and x(2) light-curve parameters. x(1) affects the light-curve width and color around peak (similar to the ?m {sub 15} and stretch parameters), and x(2) affects colors, the near-UV light-curve width, and the light-curve decline 20-30 days after peak brightness. The novel light-curve analysis, increased parameter set, and magnitude corrections of K13 may be capturing features of SN Ia diversity arising from progenitor stellar evolution.

  20. On silicon group elements ejected by supernovae type IA

    SciTech Connect (OSTI)

    De, Soma; Timmes, F. X. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ (United States); Brown, Edward F. [Joint Institute for Nuclear Astrophysics, University of Notre Dame, IN 46556 (United States); Calder, Alan C. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY (United States); Townsley, Dean M. [Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, AL (United States); Athanassiadou, Themis [Swiss National Supercomputing Centre, Via Trevano 131, 6900 Lugano (Switzerland); Chamulak, David A. [Physics Division, Argonne National Laboratory, Argonne, IL (United States); Hawley, Wendy [Laboratoire d'Astrophysique de Marseille, Marseille cedex 13 F-13388 (France); Jack, Dennis, E-mail: somad@asu.edu [Departamento de Astronomía, Universidad de Guanajuato, Apartado Postal 144, 36000 Guanajuato (Mexico)

    2014-06-01

    There is evidence that the peak brightness of a Type Ia supernova is affected by the electron fraction Y {sub e} at the time of the explosion. The electron fraction is set by the aboriginal composition of the white dwarf and the reactions that occur during the pre-explosive convective burning. To date, determining the makeup of the white dwarf progenitor has relied on indirect proxies, such as the average metallicity of the host stellar population. In this paper, we present analytical calculations supporting the idea that the electron fraction of the progenitor systematically influences the nucleosynthesis of silicon group ejecta in Type Ia supernovae. In particular, we suggest the abundances generated in quasi-nuclear statistical equilibrium are preserved during the subsequent freeze-out. This allows potential recovery of Y {sub e} at explosion from the abundances recovered from an observed spectra. We show that measurement of {sup 28}Si, {sup 32}S, {sup 40}Ca, and {sup 54}Fe abundances can be used to construct Y {sub e} in the silicon-rich regions of the supernovae. If these four abundances are determined exactly, they are sufficient to recover Y {sub e} to 6%. This is because these isotopes dominate the composition of silicon-rich material and iron-rich material in quasi-nuclear statistical equilibrium. Analytical analysis shows the {sup 28}Si abundance is insensitive to Y {sub e}, the {sup 32}S abundance has a nearly linear trend with Y {sub e}, and the {sup 40}Ca abundance has a nearly quadratic trend with Y {sub e}. We verify these trends with post-processing of one-dimensional models and show that these trends are reflected in the model's synthetic spectra.

  1. The cosmic rate of supernovae and the range of stars ending as Type Ia SNe

    E-Print Network [OSTI]

    P. Ruiz-Lapuente; R. Canal

    2000-09-20

    The present cosmic rate of Type Ia supernovae (SNeIa) suggests that about 6% of all stars in binary systems with primaries in the initial mass range $3-9\\ M\\sun$ end up as SNeIa. If that is confirmed, the unavoidable conclusion is that SNeIa can only be explained by the single degenerate scenario. At most 1% of stars in binary systems in the above range end up as CO + CO WD pairs, with total mass equal to or larger than the Chandrasekhar mass. Given that the number of mergers from pairs of CO + He WDs that reach the Chandrasekhar mass is even lower, the conclusion strongly favors binaries containing just one CO WD as the progenitors of SNeIa, since the SNeIa production efficiency (relative to the instantaneous star formation rate) predicted for double degenerate (DD) pairs lies more than $3\\sigma$ below the observational data, and the DD scenario can be rejected at more than 99% confidence level. Only if the SFR measurements from $z\\sim 0.1$ to $z\\sim 0.5$ are being underestimated by a factor of 6 while SNeIa rates are not, can we escape the above conclusion. We evaluate the numbers and characteristics of double WD systems with different chemical compositions (CO and He WDs) that should form and compare them with the observations, in order to check our predictions. Our conclusions appear robust after that test.

  2. Stellar Populations and the White Dwarf Mass Function: Connections To Supernova Ia Luminosities

    E-Print Network [OSTI]

    Ted von Hippel; G. D. Bothun; R. A. Schommer

    1997-06-11

    We discuss the luminosity function of SNe Ia under the assumption that recent evidence for dispersion in this standard candle is related to variations in the white dwarf mass function (WDMF) in the host galaxies. We develop a simple parameterization of the WDMF as a function of age of a stellar population and apply this to galaxies of different morphological types. We show that this simplified model is consistent with the observed WDMF of Bergeron et al. (1992) for the solar neighborhood. Our simple models predict that WDMF variations can produce a range of more than 1.8 mag in M$_B$(SN Ia), which is comparable to the observed value using the data of Phillips (1993) and van den Bergh (1996). We also predict a galaxy type dependence of M$_B$(SN Ia) under standard assumptions of the star formation history in these galaxies and show that M$_B$(SN Ia) can evolve with redshift. In principle both evolutionary and galaxy type corrections should be applied to recover the intrinsic range of M$_B$(SN Ia) from the observed values. Our current inadequate knowledge of the star formation history of galaxies coupled with poor physical understanding of the SN Ia mechanism makes the reliable estimation of these corrections both difficult and controversial. The predictions of our models combined with the observed galaxy and redshift correlations may have the power to discriminate between the Chandrasekhar and the sub-Chandrasekhar progenitor scenarios for SNe Ia.

  3. The Hubble Constant from Type Ia Supernovae in Early-Type Galaxies

    E-Print Network [OSTI]

    Tom Richtler; Georg Drenkhahn

    1999-09-07

    Type Ia supernovae (SNe) are the best standard candles available today in spite of an appreciable intrinsic variation of their luminosities at maximum phase, and of probably non-uniform progenitors. For an unbiased use of type Ia SNe as distance indicators it is important to know accurately how the decline rate and colour at maximum phase correlate with the peak brightness. In order to calibrate the Hubble diagram of type Ia SNe, i.e. to derive the Hubble constant, one needs to determine the absolute brightness of nearby type Ia SNe. Globular cluster systems of early type Ia host galaxies provide suitable distance indicators. We discuss how Ia SNe can be calibrated and explain the method of Globular Cluster Luminosity Functions (GCLFs). At present, the distance to the Fornax galaxy cluster is most important for deriving the Hubble constant. Our present data indicate a Hubble constant of H_0=72+-4 km/s/Mpc. As an appendix, we summarise what is known about absolute magnitudes of Ia's in late-type galaxies.

  4. GaInNAs laser gain

    SciTech Connect (OSTI)

    CHOW,WENG W.; JONES,ERIC D.; MODINE,NORMAND A.; KURTZ,STEVEN R.; ALLERMAN,ANDREW A.

    2000-05-23

    The optical gain spectra for GaInNAs/GaAs quantum wells are computed using a microscopic laser theory. From these spectra, the peak gain and carrier radiative decay rate as functions of carrier density are determined. These dependences allow the study of the lasing threshold current density of GaInNAs/GaAs quantum well structures.

  5. Advantages of the Blue InGaN/GaN Light-Emitting Diodes with an AlGaN/GaN/AlGaN Quantum Well Structured Electron Blocking Layer

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    ABSTRACT: InGaN/GaN light-emitting diodes (LEDs) with p-(AlGaN/GaN/AlGaN) quantum well structured electron. The proposed QWEBL LED structure, in which a p-GaN QW layer is inserted in the p-AlGaN electron blocking layer the radiative recombination rates across the active region. Consequently, the light output power was enhanced

  6. Red emitting photonic devices using InGaP/InGaAlP material system

    E-Print Network [OSTI]

    Kangude, Yamini

    2005-01-01

    In this thesis, two red emitting photonic devices are presented using the InGaP/InGaAlP material system. InGaP/InGaAlP material system provides large flexibility in the band gap energy while being lattice matched to GaAs ...

  7. A STUDY OF PROPERTIES OF TYPE IA SUPERNOVA AND THE CALIBRATION OF MULTIBAND PHOTOMETRY 

    E-Print Network [OSTI]

    Bastola, Deepak 1988-

    2012-04-27

    The peak luminosity of Type Ia Supernova (SN) can be calibrated using a distance independent luminosity parameter called the decline rate parameter (?m15 (B) to get accurate distances to the galaxies. The photometry gathered from the telescopes...

  8. SALT2: using distant supernovae to improve the use of Type Ia supernovae as distance indicators

    E-Print Network [OSTI]

    J. Guy; P. Astier; S. Baumont; D. Hardin; R. Pain; N. Regnault; S. Basa; R. G. Carlberg; A. Conley; S. Fabbro; D. Fouchez; I. M. Hook; D. A. Howell; K. Perrett; C. J. Pritchet; J. Rich; M. Sullivan; P. Antilogus; E. Aubourg; G. Bazin; J. Bronder; M. Filiol; N. Palanque-Delabrouille; P. Ripoche; V. Ruhlmann-Kleider

    2007-01-29

    We present an empirical model of Type Ia supernovae spectro-photometric evolution with time. The model is built using a large data set including light-curves and spectra of both nearby and distant supernovae, the latter being observed by the SNLS collaboration. We derive the average spectral sequence of Type Ia supernovae and their main variability components including a color variation law. The model allows us to measure distance moduli in the spectral range 2500-8000 A with calculable uncertainties, including those arising from variability of spectral features. Thanks to the use of high-redshift SNe to model the rest-frame UV spectral energy distribution, we are able to derive improved distance estimates for SNe Ia in the redshift range 0.8Ia supernovae.

  9. submitted to ApJ Direct Numerical Simulations of Type Ia Supernovae Flames I

    E-Print Network [OSTI]

    Bell, John B.

    for C/O thermonuclear flames at conditions relevant to the late stages of a Type Ia supernova explosion and results relevant for thermonuclear flames. Sivashinsky (1977) and Michelson & Sivashinsky (1977) studied

  10. Quantitative comparison between Type Ia supernova spectra at low and high redshifts: A case study

    E-Print Network [OSTI]

    Garavini, G.; Supernova Cosmology Project

    2008-01-01

    Highlight - The Physics of Supernovae, ESO/MPA/MPE Workshop,Evolution in high-redshift supernovae Fig. 8 “Ca ii H&K”SN 1991T/SN 1999aa-like supernovae. 1. Introduction Type Ia

  11. Imprint of modified Einstein's gravity on white dwarfs: Unifying type Ia supernovae

    E-Print Network [OSTI]

    Das, Upasana

    2015-01-01

    We establish the importance of modified Einstein's gravity (MG) in white dwarfs (WDs) for the first time in the literature. We show that MG leads to significantly sub- and super-Chandrasekhar limiting mass WDs, depending on a single model parameter. However, conventional WDs on approaching Chandrasekhar's limit are expected to trigger type Ia supernovae (SNeIa), a key to unravel the evolutionary history of the universe. Nevertheless, observations of several peculiar, under- and over-luminous SNeIa argue for the limiting mass widely different from Chandrasekhar's limit. Explosions of MG induced sub- and super-Chandrasekhar limiting mass WDs explain under- and over-luminous SNeIa respectively, thus unifying these two apparently disjoint sub-classes. Our discovery questions both the global validity of Einstein's gravity and the uniqueness of Chandrasekhar's limit.

  12. Jou~ia1of Neurochemistry Lippincott--Raven Publishers, Philadelphia

    E-Print Network [OSTI]

    Fischer, Itzhak

    Jou~ia1of Neurochemistry Lippincott--Raven Publishers, Philadelphia © 1997 International Society University, Philadelphia, Pennsylvania, U.S.A. Abstract: MAP 1 B is a microtubule-associated phospho- protein

  13. A Multi-scale Study of Inorganic Aqueous Solution (IAS) for Advanced Heat Pipe Applications

    E-Print Network [OSTI]

    Amouzegar Ashtiani, Ladan

    2015-01-01

    IAS-treated” Vs. “Clean” Cu (Working fluid: 7 mL water) Exp.water (Qu-fluid) fill charge [mL] copper surface clean cleanclean copper” identifies the pertinent experiments “Qu-fluid” (

  14. Type Ia supernovae from merging white dwarfs. II. Post-merger...

    Office of Scientific and Technical Information (OSTI)

    out multidimensional simulations of 'tamped' SN Ia models, using both particle and grid-based codes to study the merger and explosion dynamics and a radiative transfer code to...

  15. miR-153 and miR-335, Ethanol Sensitive MicroRNAs, Control NSC/NPC Maturation during Fetal Brain Development 

    E-Print Network [OSTI]

    Tsai, Pai Chi

    2014-05-05

    conclude that miR-335 and miR-153 act as molecular brakes to prevent NSCs/NPCs early maturation by regulating cell differentiation genes during the second trimester, and ethanol leads to organizational defects in the developing cerebral cortex through...

  16. GaAs, AlGaAs and InGaP Tunnel Junctions for Multi-Junction Solar Cells Under Concentration: Resistance Study

    SciTech Connect (OSTI)

    Wheeldon, Jeffrey F.; Valdivia, Christopher E.; Walker, Alex; Kolhatkar, Gitanja; Hall, Trevor J.; Hinzer, Karin; Masson, Denis; Riel, Bruno; Fafard, Simon; Jaouad, Abdelatif; Turala, Artur; Ares, Richard; Aimez, Vincent

    2010-10-14

    The following four TJ designs, AlGaAs/AlGaAs, GaAs/GaAs, AlGaAs/InGaP and AlGaAs/GaAs are studied to determine minimum doping concentration to achieve a resistance of <10{sup -4} {omega}{center_dot}cm{sup 2} and a peak tunneling current suitable for MJ solar cells up to 1500-suns concentration (operating current of 21 A/cm{sup 2}). Experimentally calibrated numerical models are used to determine how the resistance changes as a function of doping concentration. The AlGaAs/GaAs TJ design is determined to require the least doping concentration to achieve the specified resistance and peak tunneling current, followed by the GaAs/GaAs, and AlGaAs/AlGaAs TJ designs. The AlGaAs/InGaP TJ design can only achieve resistances >5x10{sup -4} {omega}cm{sup 2}.

  17. Cosmological parameter uncertainties from SALT-II type Ia supernova light curve models

    SciTech Connect (OSTI)

    Mosher, J.; Sako, M. [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Guy, J.; Astier, P.; Betoule, M.; El-Hage, P.; Pain, R.; Regnault, N. [LPNHE, CNRS/IN2P3, Université Pierre et Marie Curie Paris 6, Universié Denis Diderot Paris 7, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Kessler, R.; Frieman, J. A. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Marriner, J. [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Biswas, R.; Kuhlmann, S. [Argonne National Laboratory, 9700 South Cass Avenue, Lemont, IL 60439 (United States); Schneider, D. P., E-mail: kessler@kicp.chicago.edu [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)

    2014-09-20

    We use simulated type Ia supernova (SN Ia) samples, including both photometry and spectra, to perform the first direct validation of cosmology analysis using the SALT-II light curve model. This validation includes residuals from the light curve training process, systematic biases in SN Ia distance measurements, and a bias on the dark energy equation of state parameter w. Using the SN-analysis package SNANA, we simulate and analyze realistic samples corresponding to the data samples used in the SNLS3 analysis: ?120 low-redshift (z < 0.1) SNe Ia, ?255 Sloan Digital Sky Survey SNe Ia (z < 0.4), and ?290 SNLS SNe Ia (z ? 1). To probe systematic uncertainties in detail, we vary the input spectral model, the model of intrinsic scatter, and the smoothing (i.e., regularization) parameters used during the SALT-II model training. Using realistic intrinsic scatter models results in a slight bias in the ultraviolet portion of the trained SALT-II model, and w biases (w {sub input} – w {sub recovered}) ranging from –0.005 ± 0.012 to –0.024 ± 0.010. These biases are indistinguishable from each other within the uncertainty; the average bias on w is –0.014 ± 0.007.

  18. Measuring nickel masses in Type Ia supernovae using cobalt emission in nebular phase spectra

    E-Print Network [OSTI]

    Childress, Michael J; Seitenzahl, Ivo; Sullivan, Mark; Maguire, Kate; Taubenberger, Stefan; Scalzo, Richard; Ruiter, Ashley; Blagorodnova, Nadejda; Camacho, Yssavo; Castillo, Jayden; Elias-Rosa, Nancy; Fraser, Morgan; Gal-Yam, Avishay; Graham, Melissa; Howell, D Andrew; Inserra, Cosimo; Jha, Saurabh W; Kumar, Sahana; Mazzali, Paolo A; McCully, Curtis; Morales-Garoffolo, Antonia; Pandya, Viraj; Polshaw, Joe; Schmidt, Brian; Smartt, Stephen; Smith, Ken W; Sollerman, Jesper; Spyromilio, Jason; Tucker, Brad; Valenti, Stefano; Walton, Nicholas; Wolf, Christian; Yaron, Ofer; Young, D R; Yuan, Fang; Zhang, Bonnie

    2015-01-01

    The light curves of Type Ia supernovae (SNe Ia) are powered by the radioactive decay of $^{56}$Ni to $^{56}$Co at early times, and the decay of $^{56}$Co to $^{56}$Fe from ~60 days after explosion. We examine the evolution of the [Co III] 5892 A emission complex during the nebular phase for SNe Ia with multiple nebular spectra and show that the line flux follows the square of the mass of $^{56}$Co as a function of time. This result indicates both efficient local energy deposition from positrons produced in $^{56}$Co decay, and long-term stability of the ionization state of the nebula. We compile 77 nebular spectra of 25 SN Ia from the literature and present 17 new nebular spectra of 7 SNe Ia, including SN2014J. From these we measure the flux in the [Co III] 5892 A line and remove its well-behaved time dependence to infer the initial mass of $^{56}$Ni ($M_{Ni}$) produced in the explosion. We then examine $^{56}$Ni yields for different SN Ia ejected masses ($M_{ej}$ - calculated using the relation between light...

  19. Rates, Progenitors and Cosmic Mix of Type Ia Supernovae

    E-Print Network [OSTI]

    Laura Greggio; Alvio Renzini; Emanuele Daddi

    2008-05-29

    Following an episode of star formation, Type Ia supernova events occur over an extended period of time, following a distribution of delay times (DDT). We critically discuss some empirically-based DDT functions that have been proposed in recent years, some favoring very early (prompt) events, other very late (tardy) ones, and therefore being mutually exclusive. We point out that in both cases the derived DDT functions are affected by dubious assumptions, and therefore there is currently no ground for claiming either a DDT strongly peaked at early times, or at late ones. Theoretical DDT functions are known to accommodate both prompt as well as late SNIa events, and can account for all available observational constraints. Recent observational evidence exists that both single degenerate and double degenerate precursors may be able of producing SNIa events. We then explore on the basis of plausible theoretical models the possible variation with cosmic time of the mix between the events produced by the two different channels, which in principle could lead to systematics effects on the SNIa properties with redshift.

  20. The rates of Type Ia Supernovae. I. Analytical Formulations

    E-Print Network [OSTI]

    Laura Greggio

    2005-04-29

    This paper provides a handy tool to compute the impact of Type Ia Supernova (SNIa) on the evolution of stellar systems. An effective formalism is presented to couple the SNIa rate to the star formation history, which rests upon the definition of two key properties of the progenitor's model: the realization probability of the SNIa event from a single stellar generation and the distribution function of the delay times. It is shown that the current SNIa rate in late type galaxies implies that the realization probability is on the order of 0.001. Analytical formulations for the distribution function of the delay times for Single (SD) and Double Degenerate (DD) progenitors are derived, based on stellar evolution arguments. These formulations, which agree well with the results of Monte Carlo simulations for the evolution of close binaries, have a built in parametrization of the key properties of the alternative candidates. The various models for the progenitors have different impact on the large scales. In particular, the paper examines the systematic trend of the SNIa rate per unit mass with the color of the parent galaxy, and shows that the recent observations favor the DD model. The SD scenario can reproduce the data only if the distribution of the primordial mass ratios is flat, and the accretion efficiency onto the WD is close to 100%. The timescale for the Fe release from SNIa to the interstellar medium ranges between 0.3 and 3 Gyr for a wide variety of hypothesis on the SNIa progenitors. (ABRIDGED)

  1. GaAs MOEMS Technology

    SciTech Connect (OSTI)

    SPAHN, OLGA B.; GROSSETETE, GRANT D.; CICH, MICHAEL J.; TIGGES, CHRIS P.; RENO, JOHN L.; PEAKE, GREGORY M.; KLEM, JOHN F.; LEAN, JEN; FULLER, CHARLES T.; BURKHART, JEFF; BAUER, THOMAS; SULLIVAN, CHARLES T.

    2003-03-01

    Many MEMS-based components require optical monitoring techniques using optoelectronic devices for converting mechanical position information into useful electronic signals. While the constituent piece-parts of such hybrid opto-MEMS components can be separately optimized, the resulting component performance, size, ruggedness and cost are substantially compromised due to assembly and packaging limitations. GaAs MOEMS offers the possibility of monolithically integrating high-performance optoelectronics with simple mechanical structures built in very low-stress epitaxial layers with a resulting component performance determined only by GaAs microfabrication technology limitations. GaAs MOEMS implicitly integrates the capability for radiation-hardened optical communications into the MEMS sensor or actuator component, a vital step towards rugged integrated autonomous microsystems that sense, act, and communicate. This project establishes a new foundational technology that monolithically combines GaAs optoelectronics with simple mechanics. Critical process issues addressed include selectivity, electrochemical characteristics, and anisotropy of the release chemistry, and post-release drying and coating processes. Several types of devices incorporating this novel technology are demonstrated.

  2. Intense terahertz emission from molecular beam epitaxy-grown GaAs/GaSb(001)

    SciTech Connect (OSTI)

    Sadia, Cyril P.; Laganapan, Aleena Maria; Agatha Tumanguil, Mae; Estacio, Elmer; Somintac, Armando; Salvador, Arnel; Que, Christopher T.; Yamamoto, Kohji; Tani, Masahiko

    2012-12-15

    Intense terahertz (THz) electromagnetic wave emission was observed in undoped GaAs thin films deposited on (100) n-GaSb substrates via molecular beam epitaxy. GaAs/n-GaSb heterostructures were found to be viable THz sources having signal amplitude 75% that of bulk p-InAs. The GaAs films were grown by interruption method during the growth initiation and using various metamorphic buffer layers. Reciprocal space maps revealed that the GaAs epilayers are tensile relaxed. Defects at the i-GaAs/n-GaSb interface were confirmed by scanning electron microscope images. Band calculations were performed to infer the depletion region and electric field at the i-GaAs/n-GaSb and the air-GaAs interfaces. However, the resulting band calculations were found to be insufficient to explain the THz emission. The enhanced THz emission is currently attributed to a piezoelectric field induced by incoherent strain and defects.

  3. DLEU2, frequently deleted in malignancy, functions as a critical host gene of the cell cycle inhibitory microRNAs miR-15a and miR-16-1

    SciTech Connect (OSTI)

    Lerner, Mikael; Harada, Masako; Loven, Jakob; Castro, Juan; Davis, Zadie; Oscier, David; Henriksson, Marie; Sangfelt, Olle; Grander, Dan; Corcoran, Martin M.

    2009-10-15

    The microRNAs miR-15a and miR-16-1 are downregulated in multiple tumor types and are frequently deleted in chronic lymphocytic leukemia (CLL), myeloma and mantle cell lymphoma. Despite their abundance in most cells the transcriptional regulation of miR-15a/16-1 remains unclear. Here we demonstrate that the putative tumor suppressor DLEU2 acts as a host gene of these microRNAs. Mature miR-15a/miR-16-1 are produced in a Drosha-dependent process from DLEU2 and binding of the Myc oncoprotein to two alterative DLEU2 promoters represses both the host gene transcript and levels of mature miR-15a/miR-16-1. In line with a functional role for DLEU2 in the expression of the microRNAs, the miR-15a/miR-16-1 locus is retained in four CLL cases that delete both promoters of this gene and expression analysis indicates that this leads to functional loss of mature miR-15a/16-1. We additionally show that DLEU2 negatively regulates the G1 Cyclins E1 and D1 through miR-15a/miR-16-1 and provide evidence that these oncoproteins are subject to miR-15a/miR-16-1-mediated repression under normal conditions. We also demonstrate that DLEU2 overexpression blocks cellular proliferation and inhibits the colony-forming ability of tumor cell lines in a miR-15a/miR-16-1-dependent way. Together the data illuminate how inactivation of DLEU2 promotes cell proliferation and tumor progression through functional loss of miR-15a/miR-16-1.

  4. Utilizing Type Ia Supernovae in a Large, Fast, Imaging Survey to Constrain Dark Energy

    E-Print Network [OSTI]

    Andrew R. Zentner; Suman Bhattacharya

    2008-12-01

    We study the utility of a large sample of type Ia supernovae that might be observed in an imaging survey that rapidly scans a large fraction of the sky for constraining dark energy. We consider information from the traditional luminosity distance test as well as the spread in SNeIa fluxes at fixed redshift induced by gravitational lensing. We include a treatment of photometric redshift uncertainties in our analysis. Our primary result is that the information contained in the mean distance moduli of SNeIa and the dispersion among SNeIa distance moduli complement each other, breaking a degeneracy between the present dark energy equation of state and its time variation without the need for a high-redshift supernova sample. To address photometric redshift uncertainties, we present dark energy constraints as a function of the size of an external set of spectroscopically-observed SNeIa that may be used for redshift calibration, nspec. We find that an imaging survey can constrain the dark energy equation of state at the epoch where it is best constrained with a 1-sigma error of sigma(wpiv)~0.03-0.09$, depending upon various assumptions. In addition, the marginal improvement in the error sigma(wpiv) from an increase in the spectroscopic calibration sample drops once nspec ~ 10^3. This result is important because it is of the order of the size of calibration samples likely to be compiled in the coming decade and because, for samples of this size, the spectroscopic and imaging surveys individually place comparable constraints on the dark energy equation of state. In all cases, it is best to calibrate photometric redshifts with a set of spectroscopically-observed SNeIa with relatively more objects at high redshift than the parent sample of imaging SNeIa.

  5. Groundwater protection for the NuMI project

    SciTech Connect (OSTI)

    Wehmann, A.; Smart, W.; Menary, S.; Hylen, J.; Childress, S.

    1997-10-01

    The physics requirements for the long base line neutrino oscillation experiment MINOS dictate that the NuMI beamline be located in the aquifer at Fermilab. A methodology is described for calculating the level of radioactivation of groundwater caused by operation of this beamline. A conceptual shielding design for the 750 meter long decay pipe is investigated which would reduce radioactivation of the groundwater to below government standards. More economical shielding designs to meet these requirements are being explored. Also, information on local geology, hydrogeology, government standards, and a glossary have been included.

  6. DOE - Office of Legacy Management -- Star Cutter Corp - MI 15

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefield Municipal Gas &SCE-SessionsSouth DakotaRobbins and Myers Co - OHStar Cutter Corp - MI 15 FUSRAP

  7. DOE - Office of Legacy Management -- Westinghouse Naval Ordnance - MI 02

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefield Municipal Gas &SCE-SessionsSouth DakotaRobbins and Myers Co -VANaval Ordnance - MI 02 FUSRAP

  8. DOE - Office of Legacy Management -- Wolverine Tube Division - MI 05

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefield Municipal Gas &SCE-SessionsSouth DakotaRobbins and Myers Co -VANaval Ordnance - MI

  9. REC Silicon formerly ASiMI | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page onRAPID/Geothermal/Exploration/Colorado <RAPID/Geothermal/Water Use/NevadaaTools < RAPID79.14Silicon formerly ASiMI

  10. MHK Technologies/Mi2 | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIXsource HistoryScenarios Towards 2050Enermar < MHKHydro HelixLangleeMi2 < MHK

  11. Computational analysis of thin film InGaAs/GaAs quantum well solar cells with

    E-Print Network [OSTI]

    Yu, Edward T.

    Computational analysis of thin film InGaAs/GaAs quantum well solar cells with back side light, Austin, TX 78758, USA * ety@ece.utexas.edu Abstract: Simulations of thin film (~2.5 µm thick) InGaAs/GaAs. Roberts, G. Hill, and C. Calder, "Progress in quantum well solar cells," Thin Solid Films 511­512, 76

  12. GaSb/GaAs type II quantum dot solar cells for enhanced infrared spectral response

    E-Print Network [OSTI]

    Jalali. Bahram

    into existing multijunction cells either as a means to increase the current or efficiency by using low band gapGaSb/GaAs type II quantum dot solar cells for enhanced infrared spectral response R. B infrared spectral response of GaAs-based solar cells that incorporate type II GaSb quantum dots QDs formed

  13. The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star

    E-Print Network [OSTI]

    2008-01-01

    magnitudes of Type IA supernovae. Astrophys. J. Lett. 413,from 42 High-Redshift Supernovae. Astrophys. J. 517, 565–Observational Evidence from Supernovae for an Accelerating

  14. A New Determination of the High Redshift Type Ia Supernova Rates with the Hubble Space Telescope Advanced Camera for Surveys

    E-Print Network [OSTI]

    2008-01-01

    Schmidt, B. P. , 2003, in Supernovae and Gamma Ray Bursts,for identifying Type Ia supernovae (although spectroscopicfor future high-statistics supernovae searches in which

  15. flray Transport in Type Ia In order to solve the rate equations in a consistent manner, PHOENIX must include

    E-Print Network [OSTI]

    Nugent, Peter

    in a consistent manner, PHOENIX must include the effects of non­thermal ionization. In Type Ia supernovae the non

  16. Wind-driven evolution of white dwarf binaries to type Ia supernovae

    SciTech Connect (OSTI)

    Ablimit, Iminhaji; Xu, Xiao-jie; Li, X.-D. [Department of Astronomy, Nanjing University, Nanjing 210093 (China)

    2014-01-01

    In the single-degenerate scenario for the progenitors of Type Ia supernovae (SNe Ia), a white dwarf rapidly accretes hydrogen- or helium-rich material from its companion star and appears as a supersoft X-ray source. This picture has been challenged by the properties of the supersoft X-ray sources with very low mass companions and the observations of several nearby SNe Ia. It has been pointed out that the X-ray radiation or the wind from the accreting white dwarf can excite winds or strip mass from the companion star, thus significantly influencing the mass transfer processes. In this paper, we perform detailed calculations of the wind-driven evolution of white dwarf binaries. We present the parameter space for the possible SN Ia progenitors and for the surviving companions after the SNe. The results show that the ex-companion stars of SNe Ia have characteristics more compatible with the observations, compared with those in the traditional single-degenerate scenario.

  17. CfAIR2: Near Infrared Light Curves of 94 Type Ia Supernovae

    E-Print Network [OSTI]

    Friedman, Andrew S; Marion, G H; Challis, Peter; Mandel, Kaisey S; Bloom, Joshua S; Modjaz, Maryam; Narayan, Gautham; Hicken, Malcolm; Foley, Ryan; Klein, Christopher R; Starr, Dan L; Morgan, Adam; Rest, Armin; Blake, Cullen H; Miller, Adam A; Falco, Emilio E; Wyatt, William F; Mink, Jessica; Skrutskie, Michael F; Kirshner, Robert P

    2014-01-01

    CfAIR2 is a large homogeneously reduced set of near-infrared (NIR) light curves for Type Ia supernovae (SN Ia) obtained with the 1.3m PAIRITEL (Peters Automated InfraRed Imaging TELescope). This data set includes 4607 measurements of 94 SN Ia and 4 additional SN Iax observed from 2005-2011 at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona. CfAIR2 includes JHKs photometric measurements for 88 normal and 6 spectroscopically peculiar SN Ia in the nearby universe, with a median redshift of z~0.021 for the normal SN Ia. CfAIR2 data span the range from -13 days to +127 days from maximum in the B-band. More than half of the light curves begin before the time of maximum and the coverage typically contains ~13-18 epochs of observation, depending on the filter. We present extensive tests that verify the fidelity of the CfAIR2 data pipeline, including comparison to the excellent data of the Carnegie Supernova Project. CfAIR2 contributes to a firm local anchor for supernova cosmology studies in the NIR. ...

  18. Optical and NIR observations of the nearby type Ia supernova SN 2014J

    E-Print Network [OSTI]

    Srivastav, Shubham; Kumar, Brajesh; Anupama, G C; Sahu, D K; Ojha, D K; Prabhu, T P

    2016-01-01

    Optical and NIR observations of the type Ia supernova SN 2014J in M82 are presented. The observed light curves are found to be similar to normal SNe Ia, with a decline rate parameter $\\Delta m_{15}(B) = 1.08 \\pm 0.03$. The supernova reached $B$-band maximum on JD 2456690.14, at an apparent magnitude $m_B(max) = 11.94$. The optical spectra show a red continuum with deep interstellar Na~{\\sc i} absorption, but otherwise resemble those of normal SNe Ia. The Si~{\\sc ii} $\\lambda 6355$ feature indicates a velocity of $\\sim 12\\,000$ km s$^{-1}$ at $B$-band maximum, which places SN 2014J at the border of the Normal Velocity and High Velocity group of SNe Ia. The velocity evolution of SN 2014J places it in the Low Velocity Gradient subclass, whereas the equivalent widths of Si~{\\sc ii} features near $B$-band maximum place it at the border of the Core Normal and Broad Line subclasses of SNe Ia. An analytic model fit to the bolometric light curve indicates that a total of $\\sim 1.3$ M$_{\\odot}$ was ejected in the explo...

  19. Type Ia supernovae from merging white dwarfs. II. Post-merger detonations

    SciTech Connect (OSTI)

    Raskin, Cody; Kasen, Daniel [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Moll, Rainer; Woosley, Stan [Department of Physics and Department of Astronomy, University of California, Santa Cruz, CA (United States); Schwab, Josiah [Department of Physics and Department of Astronomy, University of California, Berkeley, CA (United States)

    2014-06-10

    Merging carbon-oxygen (CO) white dwarfs are a promising progenitor system for Type Ia supernovae (SNe Ia), but the underlying physics and timing of the detonation are still debated. If an explosion occurs after the secondary star is fully disrupted, the exploding primary will expand into a dense CO medium that may still have a disk-like structure. This interaction will decelerate and distort the ejecta. Here we carry out multidimensional simulations of 'tamped' SN Ia models, using both particle and grid-based codes to study the merger and explosion dynamics and a radiative transfer code to calculate synthetic spectra and light curves. We find that post-merger explosions exhibit an hourglass-shaped asymmetry, leading to strong variations in the light curves with viewing angle. The two most important factors affecting the outcome are the scale height of the disk, which depends sensitively on the binary mass ratio, and the total {sup 56}Ni yield, which is governed by the central density of the remnant core. The synthetic broadband light curves rise and decline very slowly, and the spectra generally look peculiar, with weak features from intermediate mass elements but relatively strong carbon absorption. We also consider the effects of the viscous evolution of the remnant and show that a longer time delay between merger and explosion probably leads to larger {sup 56}Ni yields and more symmetrical remnants. We discuss the relevance of this class of aspherical 'tamped' SN Ia for explaining the class of 'super-Chandrasekhar' SN Ia.

  20. COMPARING THE LIGHT CURVES OF SIMULATED TYPE Ia SUPERNOVAE WITH OBSERVATIONS USING DATA-DRIVEN MODELS

    SciTech Connect (OSTI)

    Diemer, Benedikt; Kessler, Richard; Graziani, Carlo; Jordan, George C. IV; Lamb, Donald Q.; Long, Min; Van Rossum, Daniel R., E-mail: bdiemer@oddjob.uchicago.edu [Flash Center for Computational Science, University of Chicago, Chicago, IL 60637 (United States)

    2013-08-20

    We propose a robust, quantitative method to compare the synthetic light curves of a Type Ia supernova (SN Ia) explosion model with a large set of observed SNe Ia, and derive a figure of merit for the explosion model's agreement with observations. The synthetic light curves are fit with the data-driven model SALT2 which returns values for stretch, color, and magnitude at peak brightness, as well as a goodness-of-fit parameter. Each fit is performed multiple times with different choices of filter bands and epoch range in order to quantify the systematic uncertainty on the fitted parameters. We use a parametric population model for the distribution of observed SN Ia parameters from large surveys, and extend it to represent red, dim, and bright outliers found in a low-redshift SN Ia data set. We discuss the potential uncertainties of this population model and find it to be reliable given the current uncertainties on cosmological parameters. Using our population model, we assign each set of fitted parameters a likelihood of being observed in nature, and a figure of merit based on this likelihood. We define a second figure of merit based on the quality of the light curve fit, and combine the two measures into an overall figure of merit for each explosion model. We compute figures of merit for a variety of one-, two-, and three-dimensional explosion models and show that our evaluation method allows meaningful inferences across a wide range of light curve quality and fitted parameters.

  1. The Host Galaxies of Type Ia Supernovae Discovered by the Palomar Transient Factory

    E-Print Network [OSTI]

    Pan, Y -C; Maguire, K; Hook, I M; Nugent, P E; Howell, D A; Arcavi, I; Botyanszki, J; Cenko, S B; DeRose, J; Fakhouri, H K; Gal-Yam, A; Hsiao, E; Kulkarni, S R; Laher, R R; Lidman, C; Nordin, J; Walker, E S; Xu, D

    2013-01-01

    We present spectroscopic observations of the host galaxies of 82 low-redshift type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF). We determine star-formation rates, gas-phase/stellar metallicities, and stellar masses and ages of these objects. As expected, strong correlations between the SN Ia light-curve width (stretch) and the host age/mass/metallicity are found: fainter, faster-declining events tend to be hosted by older/massive/metal-rich galaxies. There is some evidence that redder SNe Ia explode in higher metallicity galaxies, but we found no relation between the SN colour and host galaxy extinction based on the Balmer decrement, suggesting that the colour variation of these SNe does not primarily arise from this source. SNe Ia in higher-mass/metallicity galaxies also appear brighter after stretch/colour corrections than their counterparts in lower mass hosts, and the stronger correlation is with gas-phase metallicity suggesting this may be the more important variable. We also...

  2. New GaInP/GaAs/GaInAs, Triple-Bandgap, Tandem Solar Cell for High-Efficiency Terrestrial Concentrator Systems

    SciTech Connect (OSTI)

    Kurtz, S.; Wanlass, M.; Kramer, C.; Young, M.; Geisz, J.; Ward, S.; Duda, A.; Moriarty, T.; Carapella, J.; Ahrenkiel, P.; Emery. K.; Jones, K.; Romero, M.; Kibbler, A.; Olson, J.; Friedman, D.; McMahon, W.; Ptak, A.

    2005-11-01

    GaInP/GaAs/GaInAs three-junction cells are grown in an inverted configuration on GaAs, allowing high quality growth of the lattice matched GaInP and GaAs layers before a grade is used for the 1-eV GaInAs layer. Using this approach an efficiency of 37.9% was demonstrated.

  3. Hepatitis C Virus Infection and Hepatic Stellate Cell Activation Downregulate miR-29: miR-29 Overexpression Reduces Hepatitis C Viral Abundance in Culture

    E-Print Network [OSTI]

    Bandyopadhyay, Sarmistha

    Background.?Chronic hepatitis C virus (HCV)–induced liver fibrosis involves upregulation of transforming growth factor (TGF)–? and subsequent hepatic stellate cell (HSC) activation. MicroRNAs (miRNAs) regulate HCV infection ...

  4. Low Mach Number Modeling of Type Ia Supernovae. II. Energy Evolution

    E-Print Network [OSTI]

    A. S. Almgren; J. B. Bell; C. A. Rendleman; M. Zingale

    2006-06-21

    The convective period leading up to a Type Ia supernova (SN Ia) explosion is characterized by very low Mach number flows, requiring hydrodynamical methods well-suited to long-time integration. We continue the development of the low Mach number equation set for stellar scale flows by incorporating the effects of heat release due to external sources. Low Mach number hydrodynamics equations with a time-dependent background state are derived, and a numerical method based on the approximate projection formalism is presented. We demonstrate through validation with a fully compressible hydrodynamics code that this low Mach number model accurately captures the expansion of the stellar atmosphere as well as the local dynamics due to external heat sources. This algorithm provides the basis for an efficient simulation tool for studying the ignition of SNe Ia.

  5. Spectral Modeling of SNe Ia Near Maximum Light: Probing the Characteristics of Hydro Models

    E-Print Network [OSTI]

    E. Baron; S. Bongard; David Branch; Peter H. Hauschildt

    2006-03-03

    We have performed detailed NLTE spectral synthesis modeling of 2 types of 1-D hydro models: the very highly parameterized deflagration model W7, and two delayed detonation models. We find that overall both models do about equally well at fitting well observed SNe Ia near to maximum light. However, the Si II 6150 feature of W7 is systematically too fast, whereas for the delayed detonation models it is also somewhat too fast, but significantly better than that of W7. We find that a parameterized mixed model does the best job of reproducing the Si II 6150 line near maximum light and we study the differences in the models that lead to better fits to normal SNe Ia. We discuss what is required of a hydro model to fit the spectra of observed SNe Ia near maximum light.

  6. [O I] ??6300, 6364 IN THE NEBULAR SPECTRUM OF A SUBLUMINOUS TYPE Ia SUPERNOVA

    SciTech Connect (OSTI)

    Taubenberger, S.; Kromer, M.; Hillebrandt, W. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany)] [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany); Pakmor, R. [Heidelberger Institut für Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany)] [Heidelberger Institut für Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Pignata, G. [Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago (Chile)] [Departamento de Ciencias Fisicas, Universidad Andres Bello, Avda. Republica 252, Santiago (Chile); Maeda, K. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)] [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Hachinger, S. [Julius-Maximilians-Universität Würzburg, Emil-Fischer-Str. 31, D-97074 Würzburg (Germany)] [Julius-Maximilians-Universität Würzburg, Emil-Fischer-Str. 31, D-97074 Würzburg (Germany); Leibundgut, B. [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany)] [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany)

    2013-10-01

    In this Letter, a late-phase spectrum of SN 2010lp, a subluminous Type Ia supernova (SN Ia), is presented and analyzed. As in 1991bg-like SNe Ia at comparable epochs, the spectrum is characterized by relatively broad [Fe II] and [Ca II] emission lines. However, instead of narrow [Fe III] and [Co III] lines that dominate the emission from the innermost regions of 1991bg-like supernovae (SNe), SN 2010lp shows [O I] ??6300, 6364 emission, usually associated with core-collapse SNe and never previously observed in a subluminous thermonuclear explosion. The [O I] feature has a complex profile with two strong, narrow emission peaks. This suggests that oxygen is distributed in a non-spherical region close to the center of the ejecta, severely challenging most thermonuclear explosion models discussed in the literature. We conclude that, given these constraints, violent mergers are presently the most promising scenario to explain SN 2010lp.

  7. The Late-Time Rebrightening of Type Ia SN 2005gj in the Mid-Infrared

    E-Print Network [OSTI]

    Fox, Ori D

    2013-01-01

    A growing number of observations reveal a subset of Type Ia supernovae undergoing circumstellar interaction (SNe Ia-CSM). We present unpublished archival Spitzer Space Telescope data on SNe Ia-CSM 2002ic and 2005gj obtained > 1300 and 500 days post-discovery, respectively. Both SNe show evidence for late-time mid-infrared (mid-IR) emission from warm dust. The dust parameters are most consistent with a pre-existing dust shell that lies beyond the forward-shock radius, most likely radiatively heated by optical and X-ray emission continuously generated by late-time CSM interaction. In the case of SN 2005gj, the mid-IR luminosity more than doubles after 1 year post-discovery. While we are not aware of any late-time optical-wavelength observations at these epochs, we attribute this rebrightening to renewed shock interaction with a dense circumstellar shell.

  8. Global identification of miRNAs and targets in Populus euphratica under salt stress

    E-Print Network [OSTI]

    Deng, Xing-Wang

    Global identification of miRNAs and targets in Populus euphratica under salt stress Bosheng Li, a typical hydro-halophyte, is ideal for studying salt stress responses in woody plants. MicroRNAs (miRNA may regulate tolerance to salt stress but this has not been widely studied in P. euphratica

  9. Restoration of tumor suppressor miR-34 inhibits human p53-mutant gastric cancer tumorspheres

    E-Print Network [OSTI]

    Ji, Qing; Hao, Xinbao; Meng, Yang; Zhang, Min; DeSano, Jeffrey; Fan, Daiming; Xu, Liang

    2008-09-21

    Background: MicroRNAs (miRNAs), some of which function as oncogenes or tumor suppressor genes, are involved in carcinogenesis via regulating cell proliferation and/or cell death. MicroRNA miR-34 was recently found to be a direct target of p53...

  10. Ultraviolet observations of Super-Chandrasekhar mass type Ia supernova candidates with swift UVOT

    SciTech Connect (OSTI)

    Brown, Peter J.; Smitka, Michael T.; Krisciunas, Kevin; Wang, Lifan [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A and M University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843 (United States); Kuin, Paul; De Pasquale, Massimiliano [Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking Surrey, RH5 6NT (United Kingdom); Scalzo, Richard [Research School of Astronomy and Astrophysics, The Australian National University, Mount Stromlo Observatory, Cotter Road, Weston Creek, ACT 2611 (Australia); Holland, Stephen [Space Telescope Science Center 3700 San Martin Drive, Baltimore, MD 21218 (United States); Milne, Peter, E-mail: pbrown@physics.tamu.edu [Steward Observatory, University of Arizona, Tucson, AZ 85719 (United States)

    2014-05-20

    Among Type Ia supernovae (SNe Ia), a class of overluminous objects exist whose ejecta mass is inferred to be larger than the canonical Chandrasekhar mass. We present and discuss the UV/optical photometric light curves, colors, absolute magnitudes, and spectra of three candidate Super-Chandrasekhar mass SNe—2009dc, 2011aa, and 2012dn—observed with the Swift Ultraviolet/Optical Telescope. The light curves are at the broad end for SNe Ia, with the light curves of SN 2011aa being among the broadest ever observed. We find all three to have very blue colors which may provide a means of excluding these overluminous SNe from cosmological analysis, though there is some overlap with the bluest of 'normal' SNe Ia. All three are overluminous in their UV absolute magnitudes compared to normal and broad SNe Ia, but SNe 2011aa and 2012dn are not optically overluminous compared to normal SNe Ia. The integrated luminosity curves of SNe 2011aa and 2012dn in the UVOT range (1600-6000 Å) are only half as bright as SN 2009dc, implying a smaller {sup 56}Ni yield. While it is not enough to strongly affect the bolometric flux, the early time mid-UV flux makes a significant contribution at early times. The strong spectral features in the mid-UV spectra of SNe 2009dc and 2012dn suggest a higher temperature and lower opacity to be the cause of the UV excess rather than a hot, smooth blackbody from shock interaction. Further work is needed to determine the ejecta and {sup 56}Ni masses of SNe 2011aa and 2012dn and to fully explain their high UV luminosities.

  11. InGaAsN/GaAs heterojunction for multi-junction solar cells

    DOE Patents [OSTI]

    Kurtz, Steven R. (Albuquerque, NM); Allerman, Andrew A. (Albuquerque, NM); Klem, John F. (Albuquerque, NM); Jones, Eric D. (Edgewood, NM)

    2001-01-01

    An InGaAsN/GaAs semiconductor p-n heterojunction is disclosed for use in forming a 0.95-1.2 eV bandgap photodetector with application for use in high-efficiency multi-junction solar cells. The InGaAsN/GaAs p-n heterojunction is formed by epitaxially growing on a gallium arsenide (GaAs) or germanium (Ge) substrate an n-type indium gallium arsenide nitride (InGaAsN) layer having a semiconductor alloy composition In.sub.x Ga.sub.1-x As.sub.1-y N.sub.y with 0GaAs layer, with the InGaAsN and GaAs layers being lattice-matched to the substrate. The InGaAsN/GaAs p-n heterojunction can be epitaxially grown by either molecular beam epitaxy (MBE) or metalorganic chemical vapor deposition (MOCVD). The InGaAsN/GaAs p-n heterojunction provides a high open-circuit voltage of up to 0.62 volts and an internal quantum efficiency of >70%.

  12. Reesman, summer 2007 1 Summer 2007 Research on The Effect of Galaxy Properties on Type Ia Supernova

    E-Print Network [OSTI]

    Cinabro, David

    Reesman, summer 2007 1 Summer 2007 Research on The Effect of Galaxy Properties on Type Ia Supernova, we wanted to compare super nova type 1A host galaxy trends to results previously obtained was investigated. Type Ia Supernova are of great interest to cosmologist since they are standardize able candles

  13. Band Structure of Strain-Balanced GaAsBi/GaAsN Super-lattices on GaAs

    SciTech Connect (OSTI)

    Hwang, J.; Phillips, J. D.

    2011-05-31

    GaAs alloys with dilute content of Bi and N provide a large reduction in band-gap energy with increasing alloy composition. GaAsBi/GaAsN heterojunctions have a type-II band alignment, where superlattices based on these materials offer a wide range for designing effective band-gap energy by varying superlattice period and alloy composition. The miniband structure and effective band gap for strain-balanced GaAsBi/GaAsN superlattices with effective lattice match to GaAs are calculated for alloy compositions up to 5% Bi and N using the k·p method. The effective band gap for these superlattices is found to vary between 0.89 and 1.32 eV for period thickness ranging from 10 to 100 Å. The joint density of states and optical absorption of a 40/40 Å GaAs0.96Bi0.04/GaAs0.98N0.02 superlattice are reported demonstrating a ground-state transition at 1.005 eV and first excited transition at 1.074 eV. The joint density of states is similar in magnitude to GaAs, while the optical absorption is approximately one order of magnitude lower due to the spatially indirect optical transition in the type-II structure. The GaAsBi/GaAsN system may provide a new material system with lattice match to GaAs in a spectral range of high importance for optoelectronic devices including solar cells, photodetectors, and light emitters.

  14. Multi-color light curves of type Ia supernovae on the color-magnitude diagram: A novel step toward more precise distance and extinction estimates

    E-Print Network [OSTI]

    Wang, Lifan; Goldhaber, Gerson; Aldering, Greg; Perlmutter, Saul

    2003-01-01

    Date is earlier than for supernovae with smaller ?m 15 . SeeLight Curves of Type Ia Supernovae on the Color-Magnituderelation of Type Ia supernovae after optical maximum can

  15. Magnetism and transport properties of epitaxial Fe-Ga thin films on GaAs(001)

    SciTech Connect (OSTI)

    Duong Anh Tuan; Shin, Yooleemi; Cho, Sunglae; Dang Duc Dung; Vo Thanh Son

    2012-04-01

    Epitaxial Fe-Ga thin films in disordered bcc {alpha}-Fe crystal structure (A2) have been grown on GaAs(001) by molecular beam epitaxy. The saturated magnetization (M{sub S}) decreased from 1371 to 1105 kA/m with increasing Ga concentration from 10.5 to 24.3 % at room temperature. The lattice parameter increased with the increase in Ga content because of the larger atomic radius of Ga atom than that of Fe. The increase in carrier density with Ga content caused in lower resistivity.

  16. Graphene induced remote surface scattering in graphene/AlGaN/GaN heterostructures

    SciTech Connect (OSTI)

    Liu, Xiwen; Li, Dan; Wang, Bobo; Liu, Bin; Chen, Famin; Jin, Guangri; Lu, Yanwu, E-mail: ywlu@bjtu.edu.cn [Department of Physics, Beijing Jiaotong University, Beijing 100044 (China)

    2014-10-20

    The mobilities of single-layer graphene combined with AlGaN/GaN heterostructures on two-dimensional electron gases in graphene/AlGaN/GaN double heterojunction are calculated. The impact of electron density in single-layer graphene is also studied. Remote surface roughness (RSR) and remote interfacial charge (RIC) scatterings are introduced into this heterostructure. The mobilities limited by RSR and RIC are an order of magnitude higher than that of interface roughness and misfit dislocation. This study contributes to designing structures for generation of higher electron mobility in graphene/AlGaN/GaN double heterojunction.

  17. Predicting the amount of hydrogen stripped by the SN explosion for SN 2002cx-like SNe Ia

    SciTech Connect (OSTI)

    Liu, Zheng-Wei; Chen, X. F.; Wang, B.; Han, Z. W. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Kromer, M. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany); Fink, M.; Röpke, F. K. [Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, D-97074 Würzburg (Germany); Pakmor, R., E-mail: zwliu@ynao.ac.cn [Heidelberger Institut für Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany)

    2013-12-01

    The most favored progenitor scenarios for Type Ia supernovae (SNe Ia) involve the single-degenerate (SD) scenario and the double-degenerate scenario. The absence of stripped hydrogen (H) in the nebular spectra of SNe Ia challenges the SD progenitor models. Recently, it was shown that pure deflagration explosion models of Chandrasekhar-mass white dwarfs, ignited off-center, reproduce the characteristic observational features of 2002cx-like SNe Ia very well. In this work we predict, for the first time, the amount of stripped H for the off-center, pure deflagration explosions. We find that their low kinetic energies lead to inefficient H mass stripping (? 0.01 M {sub ?}), indicating that the stripped H may be hidden in (observed) late-time spectra of SN 2002cx-like SNe Ia.

  18. Type-Ia supernova rates to redshift 2.4 from clash: The cluster lensing and supernova survey with Hubble

    SciTech Connect (OSTI)

    Graur, O.; Rodney, S. A.; Riess, A. G.; Medezinski, E. [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218 (United States); Maoz, D. [School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978 (Israel); Jha, S. W.; Holoien, T. W.-S.; McCully, C.; Patel, B. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Postman, M.; Dahlen, T.; Strolger, L.-G.; Coe, D.; Bradley, L.; Koekemoer, A. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Benítez, N.; Molino, A. [Instituto de Astrofísica de Andalucía (CSIC), E-18080 Granada (Spain); Jouvel, S. [Institut de Ciencies de l'Espai, (IEEC-CSIC), E-08193 Bellaterra (Barcelona) (Spain); Nonino, M.; Balestra, I., E-mail: orgraur@jhu.edu [INAF-Osservatorio Astronomico di Trieste, I-34143 Trieste (Italy); and others

    2014-03-01

    We present the supernova (SN) sample and Type-Ia SN (SN Ia) rates from the Cluster Lensing And Supernova survey with Hubble (CLASH). Using the Advanced Camera for Surveys and the Wide Field Camera 3 on the Hubble Space Telescope (HST), we have imaged 25 galaxy-cluster fields and parallel fields of non-cluster galaxies. We report a sample of 27 SNe discovered in the parallel fields. Of these SNe, ?13 are classified as SN Ia candidates, including four SN Ia candidates at redshifts z > 1.2. We measure volumetric SN Ia rates to redshift 1.8 and add the first upper limit on the SN Ia rate in the range 1.8 < z < 2.4. The results are consistent with the rates measured by the HST/GOODS and Subaru Deep Field SN surveys. We model these results together with previous measurements at z < 1 from the literature. The best-fitting SN Ia delay-time distribution (DTD; the distribution of times that elapse between a short burst of star formation and subsequent SN Ia explosions) is a power law with an index of ?1.00{sub ?0.06(0.10)}{sup +0.06(0.09)} (statistical){sub ?0.08}{sup +0.12} (systematic), where the statistical uncertainty is a result of the 68% and 95% (in parentheses) statistical uncertainties reported for the various SN Ia rates (from this work and from the literature), and the systematic uncertainty reflects the range of possible cosmic star-formation histories. We also test DTD models produced by an assortment of published binary population synthesis (BPS) simulations. The shapes of all BPS double-degenerate DTDs are consistent with the volumetric SN Ia measurements, when the DTD models are scaled up by factors of 3-9. In contrast, all BPS single-degenerate DTDs are ruled out by the measurements at >99% significance level.

  19. AlGaAsSb/GaSb Distributed Bragg Reflectors Grown by Organometallic Vapor Phase Epitaxy

    SciTech Connect (OSTI)

    C.A. Wang; C.J. Vineis; D.R. Calawa

    2002-02-13

    The first AlGaAsSb/GaSb quarter-wave distributed Bragg reflectors grown by metallic vapor phase epitaxy are reported. The peak reflectance is 96% for a 10-period structure.

  20. Impact of electrochemical process on the degradation mechanisms of AlGaN/GaN HEMTs

    E-Print Network [OSTI]

    Gao, Feng, Ph. D. Massachusetts Institute of Technology

    2014-01-01

    AlGaN/GaN high electron mobility transistors (HEMTs) constitute a new generation of transistors with excellent electrical characteristics and great potential to replace silicon technology in the future, especially in high ...

  1. Cosmology with Photometrically-Classified Type Ia Supernovae from the SDSS-II Supernova Survey

    E-Print Network [OSTI]

    Campbell, Heather; Nichol, Robert C; Sako, Masao; Smith, Mathew; Lampeitl, Hubert; Olmstead, Matthew D; Bassett, Bruce; Biswas, Rahul; Brown, Peter; Cinabro, David; Dawson, Kyle S; Dilday, Ben; Foley, Ryan J; Frieman, Joshua A; Garnavich, Peter; Hlozek, Renee; Jha, Saurabh W; Kuhlmann, Steve; Kunz, Martin; Marriner, John; Miquel, Ramon; Richmond, Michael; Riess, Adam; Schneider, Donald P; Sollerman, Jesper; Taylor, Matt; Zhao, Gong-Bo

    2012-01-01

    We present the cosmological analysis of 752 photometrically-classified Type Ia Supernovae (SNe Ia) obtained from the full Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey, supplemented with host-galaxy spectroscopy from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). Our photometric-classification method is based on the SN typing technique of Sako et al. (2011), aided by host galaxy redshifts (0.05Ia typing efficiency of 70.8%, with only 3.9% contamination from core-collapse (non-Ia) SNe. We demonstrate that this level of contamination has no effect on our cosmological constraints. We quantify and correct for our selection effects (e.g., Malmquist bias) using simulations. When fitting to a flat LambdaCDM cosmological model, we find that our photometric sample alone gives omega_m=0.24+0.07-0.05 (statistical errors only). If we relax the constraint on flatness, then our sample provides competitive joint stati...

  2. Easter Term 2015 Examination Timetables (from 6 April 15 May Exams) Architecture Tripos Part IA

    E-Print Network [OSTI]

    Easter Term 2015 Examination Timetables (from 6 April ­ 15 May Exams) Contents Architecture Tripos Part IA Architecture Tripos Part IB Architecture Tripos Part II Chemical Engineering Tripos Part IIA of Philosophy Examination in Technology Policy for the degree of Master of Philosophy Examination in Theology

  3. LOW MACH NUMBER MODELING OF TYPE Ia SUPERNOVAE. I. HYDRODYNAMICS A. S. Almgren,1

    E-Print Network [OSTI]

    Bell, John B.

    LOW MACH NUMBER MODELING OF TYPE Ia SUPERNOVAE. I. HYDRODYNAMICS A. S. Almgren,1 J. B. Bell,1 C. A. Rendleman,1 and M. Zingale2 Received 2005 August 5; accepted 2005 September 29 ABSTRACT We introduce a low is derived from the fully compressible equations using low Mach number asymptotics, but without any

  4. Type Ia supernovae in a hierarchical galaxy formation model: the Milky Way

    E-Print Network [OSTI]

    Masahiro Nagashima; Takashi Okamoto

    2006-02-03

    We investigate chemical evolution in Milky Way-like galaxies based on the cold dark matter model in which cosmic structures form via hierarchical merging. We introduce chemical enrichment due to type Ia supernovae (SNe Ia) into the Mitaka semi-analytic galaxy formation model developed by Nagashima & Yoshii. For the first time we derive distributions of stellar metallicities and their ratios in Milky Way-like galaxies treating chemical enrichment due to SNe Ia in a hierarchical galaxy formation model self-consistently. As a first attempt, we assume all SNe Ia to have the same lifetime, and assume instantaneous recycling for type II supernovae (SNe II). We find that our model reproduces well the metal abundance ratio [O/Fe] against [Fe/H] and the {iron metallicity distribution function} in the solar neighborhood. This means that the so-called G-dwarf problem is resolved by the hierarchical formation of galaxies, and a gas infall term introduced in traditional monolithic collapse models to solve this problem is well explained by the mixture of some physical processes such as hierarchical merging of dark halos, gas cooling, energy feedback and injection of gas and metals into hot gas due to supernovae. Our model predicts more oxygen-enhanced stars in bulges at [Fe/H] $\\simeq 0$ than in disks. This trend seems to be supported by recent observations while they have still uncertainties. More data in number and accuracy will provide independent and important constraints on galaxy formation. (abridged)

  5. I-A Modulated Digitally Controlled Non-Inverting Buck-Boost Converter for

    E-Print Network [OSTI]

    I-A Modulated Digitally Controlled Non-Inverting Buck-Boost Converter for WCDMA RF Power Amplifiers.edu Abstract- This paper focuses on the non-inverting buck- boost converter supplying an adjustable DC voltage the WCDMA RFPA settling time requirements. 1. INTRODUCTION Non-inverting buck-boost DC-DC power converter

  6. Properties and alignment of interstellar dust grains toward Type Ia Supernovae with anomalous polarization curves

    E-Print Network [OSTI]

    Hoang, Thiem

    2015-01-01

    Recent photometric and polarimetric observations of type Ia supernovae (SNe Ia) show unusually low total-to-selective extinction ratio ($R_{V}<2$) and wavelength of maximum polarization ($\\lambda_{max}<0.4\\mu m$) for several SNe Ia, which indicates peculiar properties of interstellar (IS) dust in the SN hosted galaxies and/or the presence of circumstellar (CS) dust. In this paper, we use inversion technique to infer best-fit grain size distribution and alignment function of interstellar grains along the lines of sight toward four SNe Ia with anomalous extinction and polarization data (SNe 1986G, 2006X, 2008fp, and 2014J). We find that to reproduce low values of $R_{V}$, a significant enhancement in the mass of small grains of radius $a< 0.1\\mu m$ is required. For SN 2014J, a simultaneous fit to observed extinction and polarization data is unsuccessful if the entire data is attributed to IS dust (model 1), but a good fit is obtained when accounting for the contribution of CS dust (model 2). For SN 200...

  7. Type Ia supernovae observations support the hypothesis of a static universe

    E-Print Network [OSTI]

    David F. Crawford

    2015-09-24

    This paper considers the hypothesis that the universe is static and demonstrates that type Ia supernova observations which appear to provide strong support for time dilation (and thus for an expanding universe) are in agreement with a static universe. An important anomaly is discovered in the standard calibration method which is that the reference template light curves have widths that are proportional to the rest-frame wavelength. The implication is that the observed light-curve widths do not show time dilation. Thus the time-dilation corrections are unwarranted and the universe is static. An important consideration is the Phillips relation, a correlation between the peak luminosity and the width of type Ia supernovae. Using the Phillips relation the analysis of a recent compilation of type Ia supernova observations is re-examined and it is shown that these observations are consistent with a static universe. It is also argued that the photometric redshift relation and spectroscopic ages are consistent with a static universe. As a separate but related issue it is shown that in the static model the density distribution of type Ia supernovae as a function of redshift agrees with the observations. All the evidence shows that the hypothesis of a static universe is supported.

  8. G-Mode Excitation During the Pre-explosive Simmering of Type Ia Supernovae

    E-Print Network [OSTI]

    Piro, Anthony L

    2011-01-01

    Prior to the explosive burning of a white dwarf (WD) that makes a Type Ia supernova (SN Ia), the star "simmers" for ~10^3 yrs in a convecting, carbon burning region. I estimate the excitation of g-modes by convection during this phase and explore their possible affect on the WD. As these modes propagate from the core of the WD toward its surface, their amplitudes grow with decreasing density. Once the modes reach nonlinear amplitudes, they break and deposit their energy into a shell of mass ~10^{-4}M_\\odot. This raises the surface temperature by 6*10^8 K, which is sufficient to ignite a layer of helium, as is expected to exist for some SN Ia scenarios. This predominantly synthesizes 28Si, 32S, 40Ca, and some 44Ti. These ashes are expanded out with the subsequent explosion up to velocities of ~20,000 km/s, which may explain the high velocity features (HVFs) seen in many SNe Ia. The appearance of HVFs would therefore be a useful discriminant for determining between progenitors, since a flammable helium-rich lay...

  9. Revealing progenitors of type Ia supernovae from their light curves and spectra

    E-Print Network [OSTI]

    Kutsuna, Masamichi

    2015-01-01

    In the single degenerate (SD) scenario of type Ia supernovae (SNe Ia), the collision of the ejecta with its companion results in stripping hydrogen rich matter from the companion star. This hydrogen rich matter might leave its trace in the light curves and/or spectra. In this paper, we perform radiation hydrodynamical simulations of this collision for three binary systems. As a result, we find that the emission from the shock-heated region is not as strong as in the previous study. This weak emission, however, may be a result of our underestimate of the coupling between the gas and radiation in the shock interaction. Therefore, though our results suggest that the observed early light curves of SNe Ia can not rule out binary systems with a short separation as the progenitor system, more elaborate numerical studies will be needed to reach a fair conclusion. Alternatively, our results indicate that the feature observed in the early phase of a recent type Ia SN 2014J might result from interaction of the ejecta wi...

  10. IAS 3353 001 Modern Brazil Instructor: Dr. Erika Robb-Larkins

    E-Print Network [OSTI]

    Oklahoma, University of

    IAS 3353 001 Modern Brazil Instructor: Dr. Erika Robb-Larkins MW 3:00-4:15 p.m. Hester Hall, room an anthropological perspective. Beginning with a broad overview of Brazil's colonial history and emergence the course with an appreciation of the complexities of Brazil today.... and with a desire to hop on the next

  11. Mi2beta Is Required for c-Globin Gene Silencing: Temporal Assembly of a GATA-1-FOG-1-Mi2 Repressor Complex in b-YAC Transgenic Mice

    E-Print Network [OSTI]

    Costa, Flá via C.; Fedosyuk, Halyna; Chazelle, Allen M.; Neades, Renee Y.; Peterson, Kenneth R.

    2012-12-20

    Mi2b Is Required for c-Globin Gene Silencing: Temporal Assembly of a GATA-1-FOG-1-Mi2 Repressor Complex in b-YAC Transgenic Mice Fla´via C. Costa1¤, Halyna Fedosyuk1, Allen M. Chazelle1, Renee Y. Neades1, Kenneth R. Peterson1,2* 1Department... hemoglobin. A GATA-1-FOG-1-Mi2 repressor complex was recently demonstrated to be recruited to the 2566 GATA motif of the Ac-globin gene. We show that Mi2b is essential for c-globin gene silencing using Mi2b conditional knockout b-YAC transgenic mice...

  12. GaN nanowires show more 3D piezoelectricity than bulk GaN

    E-Print Network [OSTI]

    Espinosa, Horacio D.

    director cds murder nudity soundtrack BBC movie releases footage worth documentary film Blu-rays Blu-ray Ga

  13. miR-128 and its target genes in tumorigenesis and metastasis

    SciTech Connect (OSTI)

    Li, Molin, E-mail: molin_li@hotmail.com [Dalian Medical University, Dalian 116044 (China); Fu, Weiming [Center for Food Safety and Environmental Technology, Guangzhou Institute of Advanced Technology, Chinese Academy of Sciences, Guangzhou 511458 (China); Wo, Lulu; Shu, Xiaohong [Dalian Medical University, Dalian 116044 (China); Liu, Fang [The second affiliated hospital of Dalian Medical University, Dalian 116023 (China); Li, Chuangang, E-mail: li_chuangang@sina.com [The second affiliated hospital of Dalian Medical University, Dalian 116023 (China)

    2013-12-10

    MicroRNAs (miRNAs) are a class of endogenous, non-coding, 18–24 nucleotide length single-strand RNAs that could modulate gene expression at post-transcriptional level. Previous studies have shown that miR-128 enriched in the brain plays an important role in the development of nervous system and the maintenance of normal physical functions. Aberrant expression of miR-128 has been detected in many types of human tumors and its validated target genes are involved in cancer-related biological processes such as cell proliferation, differentiation and apoptosis. In this review, we will summarize the roles of miR-128 and its target genes in tumorigenesis and metastasis. - Highlights: • Aberrant expression of miR-128 can be observed in many kinds of malignant tumors. • The molecular mechanisms regulating miR-128 expression are elucidated. • Roles of miR-128 and its target genes in tumorigenesis and metastasis are summarized.

  14. GaInP/GaAs/GaInAs Monolithic Tandem Cells for High-Performance Solar Concentrators

    SciTech Connect (OSTI)

    Wanlass, M. W.; Ahrenkiel, S. P.; Albin, D. S.; Carapella, J. J.; Duda, A.; Emery, K.; Geisz, J. F.; Jones, K.; Kurtz, S.; Moriarty, T.; Romero, M. J.

    2005-08-01

    We present a new approach for ultra-high-performance tandem solar cells that involves inverted epitaxial growth and ultra-thin device processing. The additional degree of freedom afforded by the inverted design allows the monolithic integration of high-, and medium-bandgap, lattice-matched (LM) subcell materials with lower-bandgap, lattice-mismatched (LMM) materials in a tandem structure through the use of transparent compositionally graded layers. The current work concerns an inverted, series-connected, triple-bandgap, GaInP (LM, 1.87 eV)/GaAs (LM, 1.42 eV)/GaInAs (LMM, {approx}1 eV) device structure grown on a GaAs substrate. Ultra-thin tandem devices are fabricated by mounting the epiwafers to pre-metallized Si wafer handles and selectively removing the parent GaAs substrate. The resulting handle-mounted, ultra-thin tandem cells have a number of important advantages, including improved performance and potential reclamation/reuse of the parent substrate for epitaxial growth. Additionally, realistic performance modeling calculations suggest that terrestrial concentrator efficiencies in the range of 40-45% are possible with this new tandem cell approach. A laboratory-scale (0.24 cm2), prototype GaInP/GaAs/GaInAs tandem cell with a terrestrial concentrator efficiency of 37.9% at a low concentration ratio (10.1 suns) is described, which surpasses the previous world efficiency record of 37.3%.

  15. Spontaneous emission in GaN/InGaN photonic crystal nanopillars

    E-Print Network [OSTI]

    Boyer, Edmond

    . Sigalas, "InGaN/GaN quantum-well heterostructure light-emitting diodes employing photonic crystal, "III-nitride blue and ultraviolet photonic crystal light emitting diodes," Appl. Phys. Lett. 84, 466, and H. Benisty, "Photonic-crystal GaN light-emitting diodes with tailored guided modes distribution

  16. Switchable piezoelectric transduction in AlGaN/GaN MEMS resonators

    E-Print Network [OSTI]

    Weinstein, Dana

    This work presents a new switching mechanism in piezoelectric transduction of AlGaN/GaN bulk acoustic resonators. A piezoelectric transducer is formed in the AlGaN, between a top Schottky electrode and a 2D electron gas ...

  17. HIGH-VELOCITY LINE FORMING REGIONS IN THE TYPE Ia SUPERNOVA 2009ig

    SciTech Connect (OSTI)

    Marion, G. H.; Foley, Ryan J.; Challis, Peter; Kirshner, Robert P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Vinko, Jozsef; Wheeler, J. Craig; Silverman, Jeffrey M. [University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259 (United States); Hsiao, Eric Y. [Carnegie Observatories, Las Campanas Observatory, Colina El Pino, Casilla 601 (Chile); Brown, Peter J. [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, 4242 AMU, College Station, TX 77843 (United States); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Garnavich, Peter [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Landsman, Wayne B. [Adnet Systems, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Parrent, Jerod T. [Las Cumbres Observatory Global Telescope Network, Goleta, CA 93117 (United States); Pritchard, Tyler A.; Roming, Peter W. A. [Department of Astronomy and Astrophysics, Penn State University, 525 Davey Lab, University Park, PA 16802 (United States); Wang, Xiaofeng, E-mail: gmarion@cfa.harvard.edu [Physics Department and Tsinghua Center for Astrophysics (THCA), Tsinghua University, Beijing 1,00084 (China)

    2013-11-01

    We report measurements and analysis of high-velocity (HVF) (>20,000 km s{sup –1}) and photospheric absorption features in a series of spectra of the Type Ia supernova (SN) 2009ig obtained between –14 days and +13 days with respect to the time of maximum B-band luminosity (B-max). We identify lines of Si II, Si III, S II, Ca II, and Fe II that produce both HVF and photospheric-velocity (PVF) absorption features. SN 2009ig is unusual for the large number of lines with detectable HVF in the spectra, but the light-curve parameters correspond to a slightly overluminous but unexceptional SN Ia (M{sub B} = –19.46 mag and ?m{sub 15}(B) = 0.90 mag). Similarly, the Si II ?6355 velocity at the time of B-max is greater than 'normal' for an SN Ia, but it is not extreme (v{sub Si} = 13,400 km s{sup –1}). The –14 days and –13 days spectra clearly resolve HVF from Si II ?6355 as separate absorptions from a detached line forming region. At these very early phases, detached HVF are prevalent in all lines. From –12 days to –6 days, HVF and PVF are detected simultaneously, and the two line forming regions maintain a constant separation of about 8000 km s{sup –1}. After –6 days all absorption features are PVF. The observations of SN 2009ig provide a complete picture of the transition from HVF to PVF. Most SNe Ia show evidence for HVF from multiple lines in spectra obtained before –10 days, and we compare the spectra of SN 2009ig to observations of other SNe. We show that each of the unusual line profiles for Si II ?6355 found in early-time spectra of SNe Ia correlate to a specific phase in a common development sequence from HVF to PVF.

  18. A Test for the Nature of the Type Ia Supernova Explosion Mechanism

    E-Print Network [OSTI]

    Philip A. Pinto; Ronald G. Eastman; Tamara Rogers

    2000-08-21

    Currently popular models for Type Ia supernovae (SNe Ia) fall into two general classes. The first comprises explosions of nearly pure carbon/oxygen (C/O) white dwarfs at the Chandrasekhar limit which ignite near their centers. The second consists of lower-mass C/O cores which are ignited by the detonation of an accreted surface helium layer. Explosions of the latter type produce copious Fe, Co and Ni K-alpha emission from 56Ni and 56Co decay in the detonated surface layers, emission which is much weaker from Chandrasekhar-mass models. The presence of this emission provides a simple and unambiguous discriminant between these two models for SNe Ia. Both mechanisms may produce 0.1-0.6 solar masses of 56Ni, making them bright gamma-ray line emitters. The time to maximum brightness of 56Ni decay lines is distinctly shorter in the sub-Chandrasekhar mass class of model (approximately 15 days) than in the Chandrasekhar mass model (approximately 30 days), making gamma-ray line evolution another direct test of the explosion mechanism. It should just be possible to detect K-shell emission from a sub-Chandrasekhar explosion from SNe Ia as far away as the Virgo cluster with the XMM Observatory. A 1 to 2 square meter X-ray telescope such as the proposed Con-X Observatory could observe K-alpha emission from sub-Chandrasekhar mass SNe Ia in the Virgo cluster, providing not just a detection, but high-accuracy flux and kinematic information.

  19. TYPE Ia SUPERNOVA COLORS AND EJECTA VELOCITIES: HIERARCHICAL BAYESIAN REGRESSION WITH NON-GAUSSIAN DISTRIBUTIONS

    SciTech Connect (OSTI)

    Mandel, Kaisey S.; Kirshner, Robert P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Foley, Ryan J., E-mail: kmandel@cfa.harvard.edu [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States)

    2014-12-20

    We investigate the statistical dependence of the peak intrinsic colors of Type Ia supernovae (SNe Ia) on their expansion velocities at maximum light, measured from the Si II ?6355 spectral feature. We construct a new hierarchical Bayesian regression model, accounting for the random effects of intrinsic scatter, measurement error, and reddening by host galaxy dust, and implement a Gibbs sampler and deviance information criteria to estimate the correlation. The method is applied to the apparent colors from BVRI light curves and Si II velocity data for 79 nearby SNe Ia. The apparent color distributions of high-velocity (HV) and normal velocity (NV) supernovae exhibit significant discrepancies for B – V and B – R, but not other colors. Hence, they are likely due to intrinsic color differences originating in the B band, rather than dust reddening. The mean intrinsic B – V and B – R color differences between HV and NV groups are 0.06 ± 0.02 and 0.09 ± 0.02 mag, respectively. A linear model finds significant slopes of –0.021 ± 0.006 and –0.030 ± 0.009 mag (10{sup 3} km s{sup –1}){sup –1} for intrinsic B – V and B – R colors versus velocity, respectively. Because the ejecta velocity distribution is skewed toward high velocities, these effects imply non-Gaussian intrinsic color distributions with skewness up to +0.3. Accounting for the intrinsic-color-velocity correlation results in corrections to A{sub V} extinction estimates as large as –0.12 mag for HV SNe Ia and +0.06 mag for NV events. Velocity measurements from SN Ia spectra have the potential to diminish systematic errors from the confounding of intrinsic colors and dust reddening affecting supernova distances.

  20. Constraining Dark Energy and Cosmological Transition Redshift with Type Ia Supernovae

    E-Print Network [OSTI]

    F. Y. Wang; Z. G. Dai

    2007-08-30

    The property of dark energy and the physical reason for acceleration of the present universe are two of the most difficult problems in modern cosmology. The dark energy contributes about two-thirds of the critical density of the present universe from the observations of type-Ia supernova (SNe Ia) and anisotropy of cosmic microwave background (CMB).The SN Ia observations also suggest that the universe expanded from a deceleration to an acceleration phase at some redshift, implying the existence of a nearly uniform component of dark energy with negative pressure. We use the ``gold'' sample containing 157 SNe Ia and two recent well-measured additions, SNe Ia 1994ae and 1998aq to explore the properties of dark energy and the transition redshift. For a flat universe with the cosmological constant, we measure $\\Omega_{M}=0.28_{-0.05}^{+0.04}$, which is consistent with Riess et al. The transition redshift is $z_{T}=0.60_{-0.08}^{+0.06}$. We also discuss several dark energy models that define the $w(z)$ of the parameterized equation of state of dark energy including one parameter and two parameters ($w(z)$ being the ratio of the pressure to energy density). Our calculations show that the accurately calculated transition redshift varies from $z_{T}=0.29_{-0.06}^{+0.07}$ to $z_{T}=0.60_{-0.08}^{+0.06}$ across these models. We also calculate the minimum redshift $z_{c}$ at which the current observations need the universe to accelerate.

  1. MiR-150, A Novel and Potent Regulator for MLL-AF9 Leukemic Stem Cells 

    E-Print Network [OSTI]

    Cheruku, Patali

    2013-02-18

    Designing the miR-150 sponge primer set .................................................................. 10 Preparation of the DNA fragment containing the miR-150 sponge sequence ............ 10 Construction of pcDNA5-CMV-d2eGFP-miR150sp... protocol. Enzymatic digestion with XhoI and ApaI confirmed the insertion of the miR-150 sponge fragment. The miR-150sp-eGFP sequence (Figure 1) was then amplified using polymerase chain reaction (PCR) with the BamHI forward and SalI reverse primers, gel...

  2. Type Ia supernova rate measurements to redshift 2.5 from CANDELS: Searching for prompt explosions in the early universe

    SciTech Connect (OSTI)

    Rodney, Steven A.; Riess, Adam G.; Graur, Or; Jones, David O. [Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218 (United States); Strolger, Louis-Gregory; Dahlen, Tomas; Casertano, Stefano; Ferguson, Henry C.; Koekemoer, Anton M. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Dickinson, Mark E. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Garnavich, Peter [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Hayden, Brian [E.O. Lawrence Berkeley National Lab, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Jha, Saurabh W.; McCully, Curtis; Patel, Brandon [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Kirshner, Robert P. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Mobasher, Bahram [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Weiner, Benjamin J. [Department of Astronomy, University of Arizona, Tucson, AZ 85721 (United States); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Clubb, Kelsey I. [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); and others

    2014-07-01

    The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) was a multi-cycle treasury program on the Hubble Space Telescope (HST) that surveyed a total area of ?0.25 deg{sup 2} with ?900 HST orbits spread across five fields over three years. Within these survey images we discovered 65 supernovae (SNe) of all types, out to z ? 2.5. We classify ?24 of these as Type Ia SNe (SNe Ia) based on host galaxy redshifts and SN photometry (supplemented by grism spectroscopy of six SNe). Here we present a measurement of the volumetric SN Ia rate as a function of redshift, reaching for the first time beyond z = 2 and putting new constraints on SN Ia progenitor models. Our highest redshift bin includes detections of SNe that exploded when the universe was only ?3 Gyr old and near the peak of the cosmic star formation history. This gives the CANDELS high redshift sample unique leverage for evaluating the fraction of SNe Ia that explode promptly after formation (<500 Myr). Combining the CANDELS rates with all available SN Ia rate measurements in the literature we find that this prompt SN Ia fraction is f{sub P} = 0.53{sub stat0.10}{sup ±0.09}{sub sys0.26}{sup ±0.10}, consistent with a delay time distribution that follows a simple t {sup –1} power law for all times t > 40 Myr. However, mild tension is apparent between ground-based low-z surveys and space-based high-z surveys. In both CANDELS and the sister HST program CLASH (Cluster Lensing And Supernova Survey with Hubble), we find a low rate of SNe Ia at z > 1. This could be a hint that prompt progenitors are in fact relatively rare, accounting for only 20% of all SN Ia explosions—though further analysis and larger samples will be needed to examine that suggestion.

  3. Sweetspot: Near-infrared observations of 13 type Ia supernovae from a new NOAO survey probing the nearby smooth Hubble flow

    SciTech Connect (OSTI)

    Weyant, Anja; Wood-Vasey, W. Michael [Pittsburgh Particle physics, Astrophysics, and Cosmology Center (PITT PACC), Physics and Astronomy Department, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Allen, Lori; Joyce, Richard; Matheson, Thomas [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Garnavich, Peter M. [Department of Physics, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Jha, Saurabh W., E-mail: anw19@pitt.edu [Department of Physics and Astronomy, Rutgers, the State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States)

    2014-04-01

    We present 13 Type Ia supernovae (SNe Ia) observed in the rest-frame near-infrared (NIR) from 0.02 < z < 0.09 with the WIYN High-resolution Infrared Camera on the WIYN 3.5 m telescope. With only one to three points per light curve and a prior on the time of maximum from the spectrum used to type the object, we measure an H-band dispersion of spectroscopically normal SNe Ia of 0.164 mag. These observations continue to demonstrate the improved standard brightness of SNe Ia in an H band, even with limited data. Our sample includes two SNe Ia at z ? 0.09, which represent the most distant rest-frame NIR H-band observations published to date. This modest sample of 13 NIR SNe Ia represent the pilot sample for {sup S}weetSpot{sup —}a 3 yr NOAO Survey program that will observe 144 SNe Ia in the smooth Hubble flow. By the end of the survey we will have measured the relative distance to a redshift of z ? 0.05%-1%. Nearby Type Ia supernova (SN Ia) observations such as these will test the standard nature of SNe Ia in the rest-frame NIR, allow insight into the nature of dust, and provide a critical anchor for future cosmological SN Ia surveys at higher redshift.

  4. Computer-Generated Papercutting Jie Xu1 Craig S. Kaplan1 Xiaofeng Mi2

    E-Print Network [OSTI]

    Waterloo, University of

    Computer-Generated Papercutting Jie Xu1 Craig S. Kaplan1 Xiaofeng Mi2 1Computer Graphics Lab David Pattern #12;Related Work Kaplan and Salesin, TOG 2004 Kaplan, GI 2005 #12;Geometric Patterns Geometric

  5. Modulation of Ago-miRNA regulatory networks by cis-sequence elements and target competition

    E-Print Network [OSTI]

    Bosson, Andrew D. (Andrew David)

    2014-01-01

    regulators of gene expression in a wide range of organisms and biological processes. Each miRNA guides Argonaute (Ago) protein complexes to target and repress hundreds of genes in a sequence-dependent manner. To identify ...

  6. Scientific Achievement Networks of highly photoresponsive crystalline GaSe

    E-Print Network [OSTI]

    Geohegan, David B.

    Scientific Achievement Networks of highly photoresponsive crystalline GaSe nanosheets a crystalline GaSe target was adjusted to directly grow networks of interconnected triangular GaSe crystalline nanosheets of ~ 200 nm size (inset shows atomic

  7. Simulations of neutron multiplicity measurements with MCNP-PoliMi.

    SciTech Connect (OSTI)

    Mattingly, John K.; Pozzi, Sara A. (University of Michigan); Clarke, Shaun D. (University of Michigan); Dennis, Ben D. (University of Michigan); Miller, Eric C.

    2010-09-01

    The heightened focus on nuclear safeguards and accountability has increased the need to develop and verify simulation tools for modeling these applications. The ability to accurately simulate safeguards techniques, such as neutron multiplicity counting, aids in the design and development of future systems. This work focuses on validating the ability of the Monte Carlo code MCNPX-PoliMi to reproduce measured neutron multiplicity results for a highly multiplicative sample. The benchmark experiment for this validation consists of a 4.5-kg sphere of plutonium metal that was moderated by various thicknesses of polyethylene. The detector system was the nPod, which contains a bank of 15 3He detectors. Simulations of the experiments were compared to the actual measurements and several sources of potential bias in the simulation were evaluated. The analysis included the effects of detector dead time, source-detector distance, density, and adjustments made to the value of {nu}-bar in the data libraries. Based on this analysis it was observed that a 1.14% decrease in the evaluated value of {nu}-bar for 239Pu in the ENDF-VII library substantially improved the accuracy of the simulation.

  8. Solar Flare Measurements with STIX and MiSolFA

    E-Print Network [OSTI]

    Casadei, Diego

    2014-01-01

    Solar flares are the most powerful events in the solar system and the brightest sources of X-rays, often associated with emission of particles reaching the Earth and causing geomagnetic storms, giving problems to communication, airplanes and even black-outs. X-rays emitted by accelerated electrons are the most direct probe of solar flare phenomena. The Micro Solar-Flare Apparatus (MiSolFA) is a proposed compact X-ray detector which will address the two biggest issues in solar flare modeling. Dynamic range limitations prevent simultaneous spectroscopy with a single instrument of all X-ray emitting regions of a flare. In addition, most X-ray observations so far are inconsistent with the high anisotropy predicted by the models usually adopted for solar flares. Operated at the same time as the STIX instrument of the ESA Solar Orbiter mission, at the next solar maximum (2020), they will have the unique opportunity to look at the same flare from two different directions: Solar Orbiter gets very close to the Sun wit...

  9. Mechanistic studies of proton-coupled electron transfer in aminotyrosine- and fluorotyrosine- substituted class Ia Ribonucleotide reductase

    E-Print Network [OSTI]

    Minnihan, Ellen Catherine

    2012-01-01

    Ribonucleotide reductase (RNR) catalyzes the conversion of nucleotides to 2'- deoxynucleotides in all organisms. The class Ia RNR from Escherichia coli is active as an a2p2 complex and utilizes an unprecedented mechanism ...

  10. Control of metallation and active cofactor assembly in the class Ia and Ib ribonucleotide reductases: diiron or dimanganese?

    E-Print Network [OSTI]

    Stubbe, JoAnne

    Ribonucleotide reductases (RNRs) convert nucleotides to deoxynucleotides in all organisms. Activity of the class Ia and Ib RNRs requires a stable tyrosyl radical (Y•), which can be generated by the reaction of O[subscript ...

  11. Restframe I-band Hubble diagram for type Ia supernovae up to redshift z ~; 0.5

    E-Print Network [OSTI]

    2005-01-01

    in STScI Symposium Ser. 13, Supernovae and gamma-ray bursts:Highlight: The Physics of Supernovae, ed. W. Hillebrandt &diagram for type Ia supernovae up to redshift z ? 0.5 ? S.

  12. Experto Universitario Java Enterprise Validacin e internacionalizacin 2012-2013 Depto. Ciencia de la Computacin e IA Spring

    E-Print Network [OSTI]

    Escolano, Francisco

    Experto Universitario Java Enterprise Validación e internacionalización © 2012-2013 Depto. Ciencia #12;Experto Universitario Java Enterprise Validación e internacionalización © 2012-2013 Depto. Ciencia Java Enterprise Validación e internacionalización © 2012-2013 Depto. Ciencia de la Computación e IA

  13. In vivo cofactor biosynthesis and maintenance in the class Ia ribonucleotide reductase small subunit of Escherichia coli

    E-Print Network [OSTI]

    Wu, Chia-Hung, Ph. D. Massachusetts Institute of Technology

    2009-01-01

    The small subunit ([beta]2) of Escherichia coli class Ia ribonucleotide reductases (RNRs) contains a diferric tyrosyl radical (Y*) cofactor essential for the conversion of nucleotides to deoxynucleotides that are needed ...

  14. C-Myc negatively controls the tumor suppressor PTEN by upregulating miR-26a in glioblastoma multiforme cells

    SciTech Connect (OSTI)

    Guo, Pin; Nie, Quanmin; Lan, Jin; Ge, Jianwei [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China)] [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China); Qiu, Yongming, E-mail: qiuzhoub@hotmail.com [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China) [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China); Shanghai Institute of Head Trauma, Shanghai 200127 (China); Mao, Qing, E-mail: maoq@netease.com [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China) [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China); Shanghai Institute of Head Trauma, Shanghai 200127 (China)

    2013-11-08

    Highlights: •The c-Myc oncogene directly upregulates miR-26a expression in GBM cells. •ChIP assays demonstrate that c-Myc interacts with the miR-26a promoter. •Luciferase reporter assays show that PTEN is a specific target of miR-26a. •C-Myc–miR-26a suppression of PTEN may regulate the PTEN/AKT pathway. •Overexpression of c-Myc enhances the proliferative capacity of GBM cells. -- Abstract: The c-Myc oncogene is amplified in many tumor types. It is an important regulator of cell proliferation and has been linked to altered miRNA expression, suggesting that c-Myc-regulated miRNAs might contribute to tumor progression. Although miR-26a has been reported to be upregulated in glioblastoma multiforme (GBM), the mechanism has not been established. We have shown that ectopic expression of miR-26a influenced cell proliferation by targeting PTEN, a tumor suppressor gene that is inactivated in many common malignancies, including GBM. Our findings suggest that c-Myc modulates genes associated with oncogenesis in GBM through deregulation of miRNAs via the c-Myc–miR-26a–PTEN signaling pathway. This may be of clinical relevance.

  15. Development of metallization for GaAs and AlGaAs concentrator solar cells

    SciTech Connect (OSTI)

    Tobin, S.P.

    1987-04-01

    A three-layer metallization system was developed for high temperature stability on GaAs and AlGaAs solar cells. The layers are a Pt ohmic contact metal that forms thermally stable compounds with GaAs, a TiN diffusion barrier, and a gold conductor. The solar cell structure was also designed for contact stability, with the key component being a heavily doped GaAs cap layer. Reactively sputtered TiN was found to act as an excellent barrier when deposited under the proper conditions. The conditions were carefully optimized for low resistivity and low stress in the films. A low but nonzero substrate bias during sputtering was found to be important. Solar cells with sputtered metallizations of Pt/TiN/Ti/Pt/Au were found to be thermally stable up to 500/sup 0/C for 15 minutes in vacuum. At 600/sup 0/C there was catastrophic degradation of the cells due to dissociation of uncapped GaAs surfaces. Below this temperature the metallization performed as designed. The Pt and GaAs layers reacted to form a stable PtGa compound layer that gave low contact resistance. There was no penetration of Au or GaAs through the barrier layer. These results are a very encouraging first step leading to stable, reliable GaAs and AlGaAs concentrator cells.

  16. Constraining spacetime variations of nuclear decay rates from light curves of type Ia supernovae

    E-Print Network [OSTI]

    Ivan Karpikov; Maxim Piskunov; Anton Sokolov; Sergey Troitsky

    2015-05-12

    The luminosity of fading type Ia supernovae is governed by radioactive decays of 56Ni and 56Co. The decay rates are proportional to the Fermi coupling constant G_F and, therefore, are determined by the vacuum expectation value v of the Brout-Englert-Higgs field. We use publicly available sets of light curves of type Ia supernova at various redshifts to constrain possible spacetime variations of the 56Ni decay rate. The resulting constraint is not very tight; however, it is the only direct bound on the variation of the decay rate for redshifts up to z~1. We discuss potential applications of the result to searches for non-constancy of G_F and v.

  17. SNe Ia tests of quintessence tracker cosmology in an anisotropic background

    SciTech Connect (OSTI)

    Miranda, W. [Instituto Federal da Bahia, Paulo Afonso, Bahia (Brazil); Carneiro, S.; Pigozzo, C., E-mail: welber.miranda@ifba.edu.br, E-mail: saulo.carneiro@pq.cnpq.br, E-mail: cpigozzo@ufba.br [Instituto de Física, Universidade Federal da Bahia, Salvador, Bahia (Brazil)

    2014-07-01

    We investigate the observational effects of a quintessence model in an anisotropic spacetime. The anisotropic metric is a non-rotating particular case of a generalized Gödel's metric and is classified as Bianchi III. This metric is an exact solution of the Einstein-Klein-Gordon field equations with an anisotropic scalar field ?, which is responsible for the anisotropy of the spacetime geometry. We test the model against observations of type Ia supernovae, analyzing the SDSS dataset calibrated with the MLCS2k2 fitter, and the results are compared to standard quintessence models with Ratra-Peebles potentials. We obtain a good agreement with observations, with best values for the matter and curvature density parameters ?{sub M} = 0.29 and ?{sub k}= 0.01 respectively. We conclude that present SNe Ia observations cannot, alone, distinguish a possible anisotropic axis in the cosmos.

  18. On the Brightness of Surviving Companions in Type Ia Supernova Remnants

    E-Print Network [OSTI]

    Noda, Kazuhiro; Shigeyama, Toshikazu

    2015-01-01

    The progenitor systems for type Ia supernovae are still controversial. One of the methods to test the proposed scenario for the progenitor systems is to identify companions that are supposed to survive according to the so-called single degenerate scenario. These companions might be affected by supernova ejecta. We present several numerical simulations of surviving red-giant companions whose envelopes were stripped and heated. We find that red-giants with less-massive helium cores ($\\lesssim0.30\\,M_{\\odot}$) can be so faint after the supernovae that we cannot detect them. In addition, we apply the results to the case of SNR 0509-67.5, and put constraints on the helium core mass, envelope stripping, and energy injection under the single degenerate scenario for type Ia supernovae.

  19. On the small-scale stability of thermonuclear flames in Type Ia supernovae

    E-Print Network [OSTI]

    F. K. Roepke; J. C. Niemeyer; W. Hillebrandt

    2003-05-02

    We present a numerical model which allows us to investigate thermonuclear flames in Type Ia supernova explosions. The model is based on a finite-volume explicit hydrodynamics solver employing PPM. Using the level-set technique combined with in-cell reconstruction and flux-splitting schemes we are able to describe the flame in the discontinuity approximation. We apply our implementation to flame propagation in Chandrasekhar-mass Type Ia supernova models. In particular we concentrate on intermediate scales between the flame width and the Gibson-scale, where the burning front is subject to the Landau-Darrieus instability. We are able to reproduce the theoretical prediction on the growth rates of perturbations in the linear regime and observe the stabilization of the flame in a cellular shape. The increase of the mean burning velocity due to the enlarged flame surface is measured. Results of our simulation are in agreement with semianalytical studies.

  20. Comparing the host galaxies of type Ia, type II, and type Ibc supernovae

    SciTech Connect (OSTI)

    Shao, X.; Liang, Y. C.; Chen, X. Y.; Zhong, G. H.; Deng, L. C.; Zhang, B.; Shi, W. B.; Zhou, L. [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China); Dennefeld, M. [Institut d'Astrophysique de Paris, CNRS, and Universite P. et M. Curie, 98bis Bd Arago, F-75014 Paris (France); Hammer, F.; Flores, H., E-mail: xshao@bao.ac.cn, E-mail: ycliang@bao.ac.cn [GEPI, Observatoire de Paris-Meudon, F-92195 Meudon (France)

    2014-08-10

    We compare the host galaxies of 902 supernovae (SNe), including SNe Ia, SNe II, and SNe Ibc, which are selected by cross-matching the Asiago Supernova Catalog with the Sloan Digital Sky Survey (SDSS) Data Release 7. We selected an additional 213 galaxies by requiring the light fraction of spectral observations to be >15%, which could represent well the global properties of the galaxies. Among these 213 galaxies, 135 appear on the Baldwin-Phillips-Terlevich diagram, which allows us to compare the hosts in terms of whether they are star-forming (SF) galaxies, active galactic nuclei (AGNs; including composites, LINERs, and Seyfert 2s) or absorption-line galaxies (Absorps; i.e., their related emission lines are weak or non-existent). The diagrams related to the parameters D{sub n}(4000), H?{sub A}, stellar masses, star formation rates (SFRs), and specific SFRs for the SNe hosts show that almost all SNe II and most of the SNe Ibc occur in SF galaxies, which have a wide range of stellar masses and low D{sub n}(4000). The SNe Ia hosts as SF galaxies following similar trends. A significant fraction of SNe Ia occurs in AGNs and absorption-line galaxies, which are massive and have high D{sub n}(4000). The stellar population analysis from spectral synthesis fitting shows that the hosts of SNe II have a younger stellar population than hosts of SNe Ia. These results are compared with those of the 689 comparison galaxies where the SDSS fiber captures less than 15% of the total light. These comparison galaxies appear biased toward higher 12+log(O/H) (?0.1 dex) at a given stellar mass. Therefore, we believe the aperture effect should be kept in mind when the properties of the hosts for different types of SNe are discussed.

  1. Structural and optical properties of InGaN–GaN nanowire heterostructures grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Limbach, F.; Gotschke, T.; Stoica, T.; Calarco, R.; Sutter, E.; Ciston, J.; Cusco, R.; Artus, L.; Kremling, S.; Ho?fling, S.; Worschech, L.; Gru?tzmacher, D.

    2011-01-01

    InGaN/GaN nanowire (NW) heterostructures grown by plasma assisted molecular beam epitaxy were studied in comparison to their GaN and InGaN counterparts. The InGaN/GaN heterostructure NWs are composed of a GaN NW, a thin InGaN shell, and a multifaceted InGaN cap wrapping the top part of the GaN NW. High-resolution transmission electron microscopy (HRTEM) images taken from different parts of a InGaN/GaN NW show a wurtzite structure of the GaN core and the epitaxial InGaN shell around it, while additional crystallographic domains are observed whithin the InGaN cap region. Large changes in the lattice parameter along the wire, from pure GaN to higher In concentration demonstrate the successful growth of a complex InGaN/GaN NW heterostructure. Photoluminescence (PL) spectra of these heterostructure NW ensembles show rather broad and intense emission peak at 2.1 eV. However, ?-PL spectra measured on single NWs reveal a reduced broadening of the visible luminescence. The analysis of the longitudinal optical phonon Raman peak position and its shape reveal a variation in the In content between 20% and 30%, in agreement with the values estimated by PL and HRTEM investigations. The reported studies are important for understanding of the growth and properties of NW heterostructures suitable for applications in optoelectronics and photovoltaics.

  2. Photometric selection of Type Ia supernovae in the Supernova Legacy Survey

    E-Print Network [OSTI]

    Bazin, G; Palanque-Delabrouille, N; Rich, J; Aubourg, E; Astier, P; Balland, C; Basa, S; Carlberg, R G; Conley, A; Fouchez, D; Guy, J; Hardin, D; Hook, I M; Howell, D A; Pain, R; Perrett, K; Pritchet, C J; Regnault, N; Sullivan, M; Fourmanoit, N; Gonzalez-Gaitan, S; Lidman, C; Perlmutter, S; Ripoche, P; Walker, E S

    2011-01-01

    We present a sample of 485 photometrically identified Type Ia supernova candidates mined from the first three years of data of the CFHT SuperNova Legacy Survey (SNLS). The images were submitted to a deferred processing independent of the SNLS real-time detection pipeline. Light curves of all transient events were reconstructed in the g_M, r_M, i_M and z_M filters and submitted to automated sequential cuts in order to identify possible supernovae. Pure noise and long-term variable events were rejected by light curve shape criteria. Type Ia supernova identification relied on event characteristics fitted to their light curves assuming the events to be normal SNe Ia. The light curve fitter SALT2 was used for this purpose, assigning host galaxy photometric redshifts to the tested events. The selected sample of 485 candidates is one magnitude deeper than that allowed by the SNLS spectroscopic identification. The contamination by supernovae of other types is estimated to be 4%. Testing Hubble diagram residuals with ...

  3. The Peculiar SN 2005hk: Do Some Type Ia Supernovae Explode as Deflagrations?

    E-Print Network [OSTI]

    Phillips, M M; Frieman, J A; Blinnikov, S I; De Poy, D L; Prieto, J L; Milne, P; Contreras, C; Folatelli, G; Morrell, N; Hamuy, M; Suntzeff, N B; Roth, M; González, S; Krzeminski, W; Filippenko, A V; Freedman, W L; Chornock, R; Jha, S; Madore, B F; Persson, S E; Burns, C R; Wyatt, P; Murphy, D; Foley, R J; Ganeshalingam, M; Serduke, F J D; Krisciunas, K; Bassett, B; Becker, A; Dilday, B; Eastman, J; Garnavich, P M; Holtzman, J; Kessler, R; Lampeitl, H; Marriner, J P; Frank, S; Marshall, J L; Miknaitis, G; Sako, M; Schneider, D P; Van der Heyden, K J; Yasuda, N; Yasuda, Naoki

    2006-01-01

    We present extensive u'g'r'i'BVRIYJHKs photometry and optical spectroscopy of SN 2005hk. These data reveal that SN 2005hk was nearly identical in its observed properties to SN 2002cx, which has been called ``the most peculiar known type Ia supernova.'' Both supernovae exhibited high ionization SN 1991T-like pre-maximum spectra, yet low peak luminosities like SN 1991bg. The spectra reveal that SN 2005hk, like SN 2002cx, exhibited expansion velocities that were roughly half those of typical type Ia supernovae. The R and I light curves of both supernovae were also peculiar in not displaying the secondary maximum observed for normal type Ia supernovae. Our YJH photometry of SN 2005hk reveals the same peculiarity in the near-infrared. By combining our optical and near-infrared photometry of SN 2005hk with published ultraviolet light curves obtained with the Swift satellite, we are able to construct a bolometric light curve from ~10 days before to ~60 days after B maximum. The shape and unusually low peak luminosit...

  4. The Peculiar SN 2005hk: Do Some Type Ia Supernovae Explode as Deflagrations?

    E-Print Network [OSTI]

    M. M. Phillips; W. Li; J. A. Frieman; S. I. Blinnikov; D. DePoy; J. L. Prieto; P. Milne; C. Contreras; G. Folatelli; N. Morrell; M. Hamuy; N. B. Suntzeff; M. Roth; S. Gonzalez; W. Krzeminski; A. V. Filippenko; W. L. Freedman; R. Chornock; S. Jha; B. F. Madore; S. E. Persson; C. R. Burns; P. Wyatt; D. Murphy; R. J. Foley; M. Ganeshalingam; F. J. D. Serduke; K. Krisciunas; B. Bassett; A. Becker; B. Dilday; J. Eastman; P. M. Garnavich; J. Holtzman; R. Kessler; H. Lampeitl; J. Marriner; S. Frank; J. L. Marshall; G. Miknaitis; M. Sako; D. P. Schneider; K. van der Heyden; Naoki Yasuda

    2007-03-26

    We present extensive u'g'r'i'BVRIYJHKs photometry and optical spectroscopy of SN 2005hk. These data reveal that SN 2005hk was nearly identical in its observed properties to SN 2002cx, which has been called ``the most peculiar known type Ia supernova.'' Both supernovae exhibited high ionization SN 1991T-like pre-maximum spectra, yet low peak luminosities like SN 1991bg. The spectra reveal that SN 2005hk, like SN 2002cx, exhibited expansion velocities that were roughly half those of typical type Ia supernovae. The R and I light curves of both supernovae were also peculiar in not displaying the secondary maximum observed for normal type Ia supernovae. Our YJH photometry of SN 2005hk reveals the same peculiarity in the near-infrared. By combining our optical and near-infrared photometry of SN 2005hk with published ultraviolet light curves obtained with the Swift satellite, we are able to construct a bolometric light curve from ~10 days before to ~60 days after B maximum. The shape and unusually low peak luminosity of this light curve, plus the low expansion velocities and absence of a secondary maximum at red and near-infrared wavelengths, are all in reasonable agreement with model calculations of a 3D deflagration which produces ~0.25 M_sun of 56Ni.

  5. On type IIn/Ia-CSM supernovae as exemplified by SN 2012ca

    E-Print Network [OSTI]

    Inserra, C; Smartt, S J; Benetti, S; Chen, T -W; Childress, M; Gal-Yam, A; Howell, D A; Kangas, T; Pignata, G; Polshaw, J; Sullivan, M; Smith, K W; Valenti, S; Young, D R; Parker, S; Seccull, T; McCrum, M

    2015-01-01

    We present the complete set of ultra-violet, optical and near-infrared photometry and spectroscopy for SN 2012ca, covering the period from 6 days prior to maximum light, until 531 days after maximum. The spectroscopic time series for SN 2012ca is essentially unchanged over 1.5 years, and appear to be dominated at all epochs by signatures of interaction with a dense circumstellar medium rather than the underlying supernova (SN). SN 2012ca is a member of the class of type Ia-CSM/IIn SNe, the nature of which have been debated extensively in the literature. The two leading scenarios are either a type Ia SN exploding within a dense CSM from a non-degenerate, evolved companion, or a core-collapse SN from a massive star. While some members of the class have been unequivocally associated with type Ia SNe, in other cases the association is less certain. While it is possible that Sn 2012ca does arise from a thermonuclear SN, this would require a relatively high (between 20 and 70 per cent) efficiency in converting kine...

  6. Observational constraints from SNe Ia and Gamma-Ray Bursts on a clumpy universe

    E-Print Network [OSTI]

    Nora Bretón; Ariadna Montiel

    2013-03-06

    The luminosity distance describing the effect of local inhomogeneities in the propagation of light proposed by Zeldovich-Kantowski-Dyer-Roeder (ZKDR) is tested with two probes for two distinct ranges of redshifts: supernovae Ia (SNe Ia) in 0.015 gamma-ray bursts (GRBs) in 1.547 < z < 3.57. Our analysis is performed by a Markov Chain Monte Carlo (MCMC) code that allows us to constrain the matter density parameter \\Omega_m as well as the smoothness parameter $\\alpha$ that measures the inhomogeneous-homogeneous rate of the cosmic fluid in a flat \\LambdaCDM model. The obtained best fits are (\\Omega_m=0.285^{+0.019}_{-0.018}, \\alpha= 0.856^{+0.106}_{-0.176}) from SNe Ia and (\\Omega_m=0.259^{+0.028}_{-0.028}, \\alpha=0.587^{+0.201}_{-0.202}) from GRBs, while from the joint analysis the best fits are (\\Omega_m=0.284^{+0.021}_{-0.020}, \\alpha= 0.685^{+0.164}_{-0.171}) with a \\chi^2_{\\rm red}=0.975. The value of the smoothness parameter $\\alpha$ indicates a clumped universe however it does not have an impact on the amount of dark energy (cosmological constant) needed to fit observations. This result may be an indication that the Dyer-Roeder approximation does not describe in a precise form the effects of clumpiness in the expansion of the universe.

  7. Convection during the Late Stages of Simmering in Type Ia Supernovae

    E-Print Network [OSTI]

    Anthony L. Piro; Philip Chang

    2008-01-08

    Following unstable ignition of carbon, but prior to explosion, a white dwarf (WD) in a Type Ia supernova (SN Ia) undergoes a simmering phase. During this time, a central convective region grows and encompasses ~1 Msun of the WD over a timescale of ~1000 yrs, which sets the thermal and turbulent profile for the subsequent explosion. We study this time-dependent convection and summarize some of the key features that differ from the traditional, steady-state case. We show that the long conductive timescale above the convective zone and the extraction of energy to heat the WD core leads to a decrease of the convective luminosity and characteristic velocities near the convective zone's top boundary. In addition, differences in the composition between the convective core and the conductive exterior will significantly alter the location of this boundary. In this respect, we find the biggest effect due to complete 22Ne sedimentation prior to carbon ignition. These effects add diversity to the possible WD models, which may alter the properties of the SN Ia explosion.

  8. Probing the isotropy of cosmic acceleration traced by Type Ia supernovae

    E-Print Network [OSTI]

    Javanmardi, Behnam; Kroupa, Pavel; Pflamm-Altenburg, Jan

    2015-01-01

    We present a method to test the isotropy of the magnitude-redshift relation of Type Ia Supernovae (SNe Ia) and single out the most discrepant direction (in terms of the signal-to-noise ratio) with respect to the all-sky data. Our technique accounts for possible directional variations of the corrections for SNe Ia and yields all-sky maps of the best-fit cosmological parameters with arbitrary angular resolution. To show its potential, we apply our method to the recent Union2.1 compilation, building maps with three different angular resolutions. We use a Monte Carlo method to estimate the statistical significance with which we could reject the null hypothesis that the magnitude-redshift relation is isotropic based on the properties of the observed most discrepant directions. We find that, based on pure signal-to-noise arguments, the null hypothesis cannot be rejected at any meaningful confidence level. However, if we also consider that the strongest deviations in the Union2.1 sample closely align with the dipole...

  9. Optical and ultraviolet observations of the narrow-lined type Ia SN 2012fr in NGC 1365

    SciTech Connect (OSTI)

    Zhang, Ju-Jia; Bai, Jin-Ming; Wang, Bo; Liu, Zheng-Wei [Yunnan Observatories (YNAO), Chinese Academy of Sciences, Kunming 650011 (China); Wang, Xiao-Feng; Zhao, Xu-Lin; Chen, Jun-Cheng [Physics Department and Tsinghua Center for Astrophysics (THCA), Tsinghua University, Beijing 100084 (China); Zhang, Tian-Meng, E-mail: jujia@ynao.ac.cn, E-mail: baijinming@ynao.ac.cn, E-mail: wang_xf@mail.tsinghua.edu.cn [National Astronomical Observatories of China (NAOC), Chinese Academy of Sciences, Beijing 100012 (China)

    2014-07-01

    Extensive optical and ultraviolet (UV) observations of the type Ia supernova (SN Ia) 2012fr are presented in this paper. It has a relatively high luminosity, with an absolute B-band peak magnitude of about –19.5 mag and a smaller post-maximum decline rate than normal SNe Ia (e.g., ?m {sub 15}(B) =0.85 ± 0.05 mag). Based on the UV and optical light curves, we derived that a {sup 56}Ni mass of about 0.88 M {sub ?} was synthesized in the explosion. The earlier spectra are characterized by noticeable high-velocity features of Si II ?6355 and Ca II with velocities in the range of ?22, 000-25, 000 km s{sup –1}. At around the maximum light, these spectral features are dominated by the photospheric components which are noticeably narrower than normal SNe Ia. The post-maximum velocity of the photosphere remains almost constant at ?12,000 km s{sup –1} for about one month, reminiscent of the behavior of some luminous SNe Ia like SN 1991T. We propose that SN 2012fr may represent a subset of the SN 1991T-like SNe Ia viewed in a direction with a clumpy or shell-like structure of ejecta, in terms of a significant level of polarization reported in Maund et al. in 2013.

  10. The Silicon and Calcium High-Velocity Features in Type Ia Supernovae from Early to Maximum Phases

    E-Print Network [OSTI]

    Zhao, Xulin; Maeda, Keiichi; Sai, Hanna; Zhang, Tianmeng; Zhang, Jujia; Huang, Fang; Rui, Liming; Zhou, Qi; Mo, Jun

    2015-01-01

    The high-velocity features (HVFs) in optical spectra of type Ia supernovae (SNe Ia) are examined with a large sample including very early-time spectra (e.g., t < -7 days). Multiple Gaussian fits are applied to examine the HVFs and their evolutions, using constraints on expansion velocities for the same species (i.e., SiII 5972 and SiII 6355). We find that strong HVFs tend to appear in SNe Ia with smaller decline rates (e.g., dm15(B)<1.4 mag), clarifying that the finding by Childress et al. (2014) for the Ca-HVFs in near-maximum-light spectra applies both to the Si-HVFs and Ca-HVFs in the earlier phase. The Si-HVFs seem to be more common in fast-expanding SNe Ia, which is different from the earlier result that the Ca-HVFs are associated with SNe Ia having slower SiII 6355 velocities at maximum light (i.e., Vsi). This difference can be due to that the HVFs in fast-expanding SNe Ia usually disappear more rapidly and are easily blended with the photospheric components when approaching the maximum light. Mor...

  11. miR-196a targets netrin 4 and regulates cell proliferation and migration of cervical cancer cells

    SciTech Connect (OSTI)

    Zhang, Jie; Zheng, Fangxia; Yu, Gang; Yin, Yanhua; Lu, Qingyang

    2013-11-01

    Highlights: •miR-196a was overexpressed in cervical cancer tissue compared to normal tissue. •miR-196a expression elevated proliferation and migration of cervical cancer cells. •miR-196a inhibited NTN4 expression by binding 3?-UTR region of NTN4 mRNA. •NTN4 inversely correlated with miR-196a expression in cervical tissue and cell line. •NTN4 expression was low in cervical cancer tissue compared to normal tissue. -- Abstract: Recent research has uncovered tumor-suppressive and oncogenic potential of miR-196a in various tumors. However, the expression and mechanism of its function in cervical cancer remains unclear. In this study, we assess relative expression of miR-196a in cervical premalignant lesions, cervical cancer tissues, and four cancer cell lines using quantitative real-time PCR. CaSki and HeLa cells were treated with miR-196a inhibitors, mimics, or pCDNA/miR-196a to investigate the role of miR-196a in cancer cell proliferation and migration. We demonstrated that miR-196a was overexpressed in cervical intraepithelial neoplasia 2–3 and cervical cancer tissue. Moreover, its expression contributes to the proliferation and migration of cervical cancer cells, whereas inhibiting its expression led to a reduction in proliferation and migration. Five candidate targets of miR-196a chosen by computational prediction and Cervical Cancer Gene Database search were measured for their mRNA in both miR-196a-overexpressing and -depleted cancer cells. Only netrin 4 (NTN4) expression displayed an inverse association with miR-196a. Fluorescent reporter assays revealed that miR-196a inhibited NTN4 expression by targeting one binding site in the 3?-untranslated region (3?-UTR) of NTN4 mRNA. Furthermore, qPCR and Western blot assays verified NTN4 expression was downregulated in cervical cancer tissues compared to normal controls, and in vivo mRNA level of NTN4 inversely correlated with miR-196a expression. In summary, our findings provide new insights about the functional role of miR-196a in cervical carcinogenesis and suggested a potential use of miR-196a for clinical diagnosis and as a therapeutic target.

  12. Ohmic contacts to n-GaSb 

    E-Print Network [OSTI]

    Yang, Zhengchong

    1997-01-01

    In recent years, the Ill-V semiconductor GaSb and its ternary alloys containing antimony have exhibited interesting electrical and optical properties for device applications which include negative resistance tunnel devices, lasers, detectors and FET...

  13. GaTe semiconductor for radiation detection

    DOE Patents [OSTI]

    Payne, Stephen A. (Castro Valley, CA); Burger, Arnold (Nashville, TN); Mandal, Krishna C. (Ashland, MA)

    2009-06-23

    GaTe semiconductor is used as a room-temperature radiation detector. GaTe has useful properties for radiation detectors: ideal bandgap, favorable mobilities, low melting point (no evaporation), non-hygroscopic nature, and availability of high-purity starting materials. The detector can be used, e.g., for detection of illicit nuclear weapons and radiological dispersed devices at ports of entry, in cities, and off shore and for determination of medical isotopes present in a patient.

  14. miR-421 induces cell proliferation and apoptosis resistance in human nasopharyngeal carcinoma via downregulation of FOXO4

    SciTech Connect (OSTI)

    Chen, Liang; Department of Otolaryngology, Guangzhou General Hospital of PLA Guangzhou Command, Guangzhou 510010 ; Tang, Yanping; Wang, Jian; Yan, Zhongjie; Xu, Ruxiang

    2013-06-14

    Highlights: •miR-421 is upregulated in nasopharyngeal carcinoma. •miR-421 induces cell proliferation and apoptosis resistance. •FOXO4 is a direct and functional target of miR-421. -- Abstract: microRNAs have been demonstrated to play important roles in cancer development and progression. Hence, identifying functional microRNAs and better understanding of the underlying molecular mechanisms would provide new clues for the development of targeted cancer therapies. Herein, we reported that a microRNA, miR-421 played an oncogenic role in nasopharyngeal carcinoma. Upregulation of miR-421 induced, whereas inhibition of miR-421 repressed cell proliferation and apoptosis resistance. Furthermore, we found that upregulation of miR-421 inhibited forkhead box protein O4 (FOXO4) signaling pathway following downregulation of p21, p27, Bim and FASL expression by directly targeting FOXO4 3?UTR. Additionally, we demonstrated that FOXO4 expression is critical for miR-421-induced cell growth and apoptosis resistance. Taken together, our findings not only suggest that miR-421 promotes nasopharyngeal carcinoma cell proliferation and anti-apoptosis, but also uncover a novel regulatory mechanism for inactivation of FOXO4 in nasopharyngeal carcinoma.

  15. Single-molecule modeling of mRNA degradation by miRNA: Lessons from data

    E-Print Network [OSTI]

    Celine Sin; Davide Chiarugi; Angelo Valleriani

    2014-10-20

    Recent experimental results on the effect of miRNA on the decay of its target mRNA have been analyzed against a previously hypothesized single molecule degradation pathway. According to that hypothesis, the silencing complex (miRISC) first interacts with its target mRNA and then recruits the protein complexes associated with NOT1 and PAN3 to trigger deadenylation (and subsequent degradation) of the target mRNA. Our analysis of the experimental decay patterns allowed us to refine the structure of the degradation pathways at the single molecule level. Surprisingly, we found that if the previously hypothesized network was correct, only about 7% of the target mRNA would be regulated by the miRNA mechanism, which is inconsistent with the available knowledge. Based on systematic data analysis, we propose the alternative hypothesis that NOT1 interacts with miRISC before binding to the target mRNA. Moreover, we show that when miRISC binds alone to the target mRNA, the mRNA is degraded more slowly, probably through a deadenylation-independent pathway. The new biochemical pathway we propose both fits the data and paves the way for new experimental work to identify new interactions.

  16. InGaN/GaN tunnel junctions for hole injection in GaN light emitting diodes

    SciTech Connect (OSTI)

    Krishnamoorthy, Sriram, E-mail: krishnamoorthy.13@osu.edu, E-mail: rajan@ece.osu.edu; Akyol, Fatih [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Rajan, Siddharth, E-mail: krishnamoorthy.13@osu.edu, E-mail: rajan@ece.osu.edu [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2014-10-06

    InGaN/GaN tunnel junction contacts were grown using plasma assisted molecular beam epitaxy (MBE) on top of a metal-organic chemical vapor deposition (MOCVD)-grown InGaN/GaN blue (450?nm) light emitting diode. A voltage drop of 5.3?V at 100?mA, forward resistance of 2 × 10{sup ?2} ? cm{sup 2}, and a higher light output power compared to the reference light emitting diodes (LED) with semi-transparent p-contacts were measured in the tunnel junction LED (TJLED). A forward resistance of 5?×?10{sup ?4} ? cm{sup 2} was measured in a GaN PN junction with the identical tunnel junction contact as the TJLED, grown completely by MBE. The depletion region due to the impurities at the regrowth interface between the MBE tunnel junction and the MOCVD-grown LED was hence found to limit the forward resistance measured in the TJLED.

  17. Journal of Crystal Growth 298 (2007) 272275 Dislocation analysis in homoepitaxial GaInN/GaN light emitting

    E-Print Network [OSTI]

    Wetzel, Christian M.

    2007-01-01

    of GaInN/GaN-based light emitting diodes (LED) on quasi-bulk GaN with an atomically flat polished were much improved. The optical output power of the light emitting diode increased by more than one. Cathodoluminescence; A1. Threading dislocation density; A2. Homoepitaxial growth; B1. GaInN; B3. Light emitting diode

  18. Thermoelectric effects in wurtzite GaN and AlxGa1-xN alloys and Alexander A. Balandin

    E-Print Network [OSTI]

    Thermoelectric effects in wurtzite GaN and AlxGa1-xN alloys Weili Liua and Alexander A. Balandin have investigated theoretically the thermoelectric effects in wurtzite GaN crystals and AlxGa1-xN-based alloys may have some potential as thermoelectric materials at high temperature. It was found

  19. Ultra-high frequency photoconductivity decay in GaAs/Ge/GaAs double heterostructure grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Hudait, M. K.; Zhu, Y. [Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)] [Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Johnston, S. W. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)] [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Maurya, D.; Priya, S. [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States)] [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Umbel, R. [Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)] [Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)

    2013-03-04

    GaAs/Ge/GaAs double heterostructures (DHs) were grown in-situ using two separate molecular beam epitaxy chambers. High-resolution x-ray rocking curve demonstrates a high-quality GaAs/Ge/GaAs heterostructure by observing Pendelloesung oscillations. The kinetics of the carrier recombination in Ge/GaAs DHs were investigated using photoconductivity decay measurements by the incidence excitation from the front and back side of 15 nm GaAs/100 nm Ge/0.5 {mu}m GaAs/(100)GaAs substrate structure. High-minority carrier lifetimes of 1.06-1.17 {mu}s were measured when excited from the front or from the back of the Ge epitaxial layer, suggests equivalent interface quality of GaAs/Ge and Ge/GaAs. Wavelength-dependent minority carrier recombination properties are explained by the wavelength-dependent absorption coefficient of Ge.

  20. Enhanced presentation of MHC class Ia, Ib and class II-restricted peptides encapsulated in biodegradable nanoparticles: a promising strategy for tumor immunotherapy

    E-Print Network [OSTI]

    2011-01-01

    sequences enhance MHC class I presentation of a peptide fromantigens presented on MHC class I molecules. Science 1995,Enhanced presentation of MHC class Ia, Ib and class II-

  1. Green cubic GaInN/GaN light-emitting diode on microstructured silicon (100)

    SciTech Connect (OSTI)

    Stark, Christoph J. M.; Detchprohm, Theeradetch; Wetzel, Christian, E-mail: wetzel@ieee.org [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States) [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Future Chips Constellation, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180 (United States); Lee, S. C.; Brueck, S. R. J. [Department of Electrical and Computer Engineering and Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico 87106 (United States)] [Department of Electrical and Computer Engineering and Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico 87106 (United States); Jiang, Y.-B. [Department of Earth and Planetary Science, University of New Mexico, Albuquerque, New Mexico 87131 (United States)] [Department of Earth and Planetary Science, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2013-12-02

    GaInN/GaN light-emitting diodes free of piezoelectric polarization were prepared on standard electronic-grade Si(100) substrates. Micro-stripes of GaN and GaInN/GaN quantum wells in the cubic crystal structure were grown on intersecting (111) planes of microscale V-grooved Si in metal-organic vapor phase epitaxy, covering over 50% of the wafer surface area. Crystal phases were identified in electron back-scattering diffraction. A cross-sectional analysis reveals a cubic structure virtually free of line defects. Electroluminescence over 20 to 100??A is found fixed at 487?nm (peak), 516?nm (dominant). Such structures therefore should allow higher efficiency, wavelength-stable light emitters throughout the visible spectrum.

  2. A hole accelerator for InGaN/GaN light-emitting diodes

    SciTech Connect (OSTI)

    Zhang, Zi-Hui; Liu, Wei; Tan, Swee Tiam; Ji, Yun; Wang, Liancheng; Zhu, Binbin; Zhang, Yiping; Lu, Shunpeng; Zhang, Xueliang; Hasanov, Namig; Sun, Xiao Wei, E-mail: EXWSUN@ntu.edu.sg, E-mail: VOLKAN@stanfordalumni.org [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Demir, Hilmi Volkan, E-mail: EXWSUN@ntu.edu.sg, E-mail: VOLKAN@stanfordalumni.org [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Department of Electrical and Electronics, Department of Physics, and UNAM-Institute of Material Science and Nanotechnology, Bilkent University, TR-06800 Ankara (Turkey)

    2014-10-13

    The quantum efficiency of InGaN/GaN light-emitting diodes (LEDs) has been significantly limited by the insufficient hole injection, and this is caused by the inefficient p-type doping and the low hole mobility. The low hole mobility makes the holes less energetic, which hinders the hole injection into the multiple quantum wells (MQWs) especially when a p-type AlGaN electron blocking layer (EBL) is adopted. In this work, we report a hole accelerator to accelerate the holes so that the holes can obtain adequate kinetic energy, travel across the p-type EBL, and then enter the MQWs more efficiently and smoothly. In addition to the numerical study, the effectiveness of the hole accelerator is experimentally shown through achieving improved optical output power and reduced efficiency droop for the proposed InGaN/GaN LED.

  3. Gallium surface diffusion on GaAs (001) surfaces measured by crystallization dynamics of Ga droplets

    SciTech Connect (OSTI)

    Bietti, Sergio, E-mail: sergio.bietti@mater.unimib.it; Somaschini, Claudio; Esposito, Luca; Sanguinetti, Stefano [L–NESS and Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, Via Cozzi 55, I–20125 Milano (Italy); Fedorov, Alexey [L–NESS and CNR–IFN, via Anzani 42, I-22100 Como (Italy)

    2014-09-21

    We present accurate measurements of Ga cation surface diffusion on GaAs surfaces. The measurement method relies on atomic force microscopy measurement of the morphology of nano–disks that evolve, under group V supply, from nanoscale group III droplets, earlier deposited on the substrate surface. The dependence of the radius of such nano-droplets on crystallization conditions gives direct access to Ga diffusion length. We found an activation energy for Ga on GaAs(001) diffusion E{sub A}=1.31±0.15 eV, a diffusivity prefactor of D?=0.53(×2.1±1) cm² s?¹ that we compare with the values present in literature. The obtained results permit to better understand the fundamental physics governing the motion of group III ad–atoms on III–V crystal surfaces and the fabrication of designable nanostructures.

  4. Constraints on shallow {sup 56}Ni from the early light curves of type Ia supernovae

    SciTech Connect (OSTI)

    Piro, Anthony L. [Theoretical Astrophysics, California Institute of Technology, 1200 E California Boulevard, M/C 350-17, Pasadena, CA 91125 (United States); Nakar, Ehud, E-mail: piro@caltech.edu [Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel)

    2014-03-20

    Ongoing transient surveys are presenting an unprecedented account of the rising light curves of Type Ia supernovae (SNe Ia). This early emission probes the shallowest layers of the exploding white dwarf (WD), which can provide constraints on the progenitor star and the properties of the explosive burning. We use semianalytic models of radioactively powered rising light curves to analyze these observations. As we have summarized in previous work, the main limiting factor in determining the surface distribution of {sup 56}Ni is the lack of an unambiguously identified time of explosion, as would be provided by detection of shock breakout or shock-heated cooling. Without this the SN may in principle exhibit a 'dark phase' for a few hours to days, where the only emission is from shock-heated cooling that is too dim to be detected. We show that by assuming a theoretically motivated time-dependent velocity evolution, the explosion time can be better constrained, albeit with potential systematic uncertainties. This technique is used to infer the surface {sup 56}Ni distributions of three recent SNe Ia that were caught especially early in their rise. In all three we find fairly similar {sup 56}Ni distributions. Observations of SN 2011fe and SN 2012cg probe shallower depths than SN 2009ig, and in these two cases {sup 56}Ni is present merely ?10{sup –2} M {sub ?} from the WDs' surfaces. The uncertainty in this result is up to an order of magnitude given the difficulty of precisely constraining the explosion time. We also use our conclusions about the explosion times to reassess radius constraints for the progenitor of SN 2011fe, as well as discuss the roughly t {sup 2} power law that is inferred for many observed rising light curves.

  5. IS WX CEN A POSSIBLE TYPE Ia SUPERNOVA PROGENITOR WITH WIND-DRIVEN MASS TRANSFER?

    SciTech Connect (OSTI)

    Qian, S.-B.; Shi, G.; Zhu, L.-Y.; Liu, L.; Zhao, E.-G.; Li, L.-J. [Yunnan Observatories, Chinese Academy of Sciences (CAS), P.O. Box 110, 650011 Kunming (China); Fernandez Lajus, E.; Di Sisto, R. P., E-mail: qsb@ynao.ac.cn [Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, 1900 La Plata, Buenos Aires (Argentina)

    2013-08-01

    WX Cen is one of a few compact binary supersoft X-ray sources (CBSS) in the Galaxy that is a possible Type Ia supernova (SN Ia) progenitor. The supersoft X-ray radiation is explained as hydrostatic nuclear burning on the surface of the white dwarf component that is accreting hydrogen from a stellar companion at a high rate. If the mass donor in this system has a low mass, as has been suggested in the literature, one would expect a high wind-driven mass transfer rate. In that case, the orbital period of the system should increase. To test this theoretical prediction, we have monitored the system photometrically since 2010. By using four newly determined eclipse timings together with those collected from the literature, we discovered that the orbital period is decreasing at a rate of dP/dt = -5.15 Multiplication-Sign 10{sup -7} days yr{sup -1}. The long-term decrease in the orbital period is contrary to the prediction that the system is powered by wind-driven accretion. It therefore seems plausible that the mass donor could be more massive than the white dwarf, and that the mass transfer is driven by the thermal instability of the donor star. This finding suggests that WX Cen is a key object to check the physical mechanisms of mass accretion in CBSS. The corresponding timescale of the period change is about P/P-dot {approx} 0.81 x 10{sup 6} yr, indicating that WX Cen may evolve into an SNe Ia within one million years in the Galaxy.

  6. On the Thermonuclear Runaway in Type Ia Supernovae: How to run away?

    E-Print Network [OSTI]

    P. Hoeflich; J. Stein

    2001-12-07

    Type Ia Supernovae are thought to be thermonuclear explosions of massive white dwarfs (WD). We present the first study of multi-dimensional effects during the final hours prior to the thermonuclear runaway which leads to the explosion. The calculations utilize an implicit, 2-D hydro code.Mixing and the ignition process are studied in detail. We find that the initial chemical structure of the WD is changed but the material is not fully homogenized. The exploding WD sustains a central region with a low C/O ratio. This implies that the explosive nuclear burning will begin in a partially C-depleted environment. The thermonuclear runaway happens in a well defined region close to the center. It is induced by compressional heat when matter is brought inwards by convective flows. We find no evidence for multiple spot or strong off-center ignition. Convective velocities are of the order of 100 km/sec which is well above the effective burning speeds in SNe Ia previously expected right after the runaway. For about 0.5 to 1 sec, the speed of the burning front will neither be determined by the laminar speed nor the Rayleigh-Taylor instabilities but by convective flows produced prior to the runaway. The consequences are discussed for our under- standing of the detailed physics of the flame propagation, the deflagration detonation transition, and the nucleosynthesis in the central layers. Our results strongly suggest the pre-conditioning of the progenitor as a key-factor for our understanding of the diversity in SNeIa.

  7. SN~2012cg: Evidence for Interaction Between a Normal Type Ia Supernova and a Non-Degenerate Binary Companion

    E-Print Network [OSTI]

    Marion, G H; Vinkó, Jozsef; Silverman, Jeffrey M; Sand, David J; Challis, Peter; Kirshner, Robert P; Wheeler, J Craig; Berlind, Perry; Brown, Warren R; Calkins, Michael L; Dhungana, Govinda; Foley, Ryan J; Friedman, Andrew S; Graham, Melissa L; Howell, D Andrew; Hsiao, Eric Y; Irwin, Jonathan M; Kehoe, Robert; Macri, Lucas M; Mandel, Kaisey; McCully, Curtis; Rines, Kenneth J; Wilhelmy, Steven; Zheng, Weikang

    2015-01-01

    We report evidence for excess blue light from the Type Ia supernova SN~2012cg at fifteen and sixteen days before maximum B-band brightness. The emission is consistent with predictions for the impact of the supernova on a non-degenerate binary companion. This is the first evidence for emission from a companion to a normal SN~Ia. Sixteen days before maximum light, the B-V color of SN~2012cg is 0.2 mag bluer than for other normal SN~Ia. At later times, this supernova has a typical SN~Ia light curve, with extinction-corrected M_B = -19.62 \\pm 0.02 mag and Delta m_{15}(B) = 0.86 \\pm 0.02. Our data set is extensive, with photometry in 7 filters from 5 independent sources. Early spectra also show the effects of blue light, and high-velocity features are observed at early times. Near maximum, the spectra are normal with a silicon velocity v_{Si} = -10,500 km/s. Comparing the early data with models by Kasen (2010) favors a main-sequence companion of about 6 solar masses. It is possible that many other SN Ia have main-...

  8. Ion-lithium collision dynamics studied with an in-ring MOTReMi

    E-Print Network [OSTI]

    Fischer, D; Goullon, J; Grieser, M; Hubele, R; de Jesus, V L B; Kelkar, A; LaForge, A; Lindenblatt, H; Misra, D; Najjari, B; Schneider, K; Schulz, M; Sell, M; Wang, X

    2012-01-01

    We present a novel experimental tool allowing for kinematically complete studies of break-up processes of laser-cooled atoms. This apparatus, the 'MOTReMi', is a combination of a magneto-optical trap (MOT) and a Reaction Microscope (ReMi). Operated in an ion-storage ring, the new setup enables to study the dynamics in swift ion-atom collisions on an unprecedented level of precision and detail. In first experiments on collisions with 1.5 MeV/amu O$^{8+}$-Li the pure ionization of the valence electron as well as ionization-excitation of the lithium target has been investigated.

  9. On the Stability of Thermonuclear Burning Fronts in Type Ia Supernovae

    E-Print Network [OSTI]

    F. K. Roepke; W. Hillebrandt

    2004-04-26

    The propagation of cellularly stabilized thermonuclear flames is investigated by means of numerical simulations. In Type Ia supernova explosions the corresponding burning regime establishes at scales below the Gibson length. The cellular flame stabilization - which is a result of an interplay between the Landau-Darrieus instability and a nonlinear stabilization mechanism - is studied for the case of propagation into quiescent fuel as well as interaction with vortical fuel flows. Our simulations indicate that in thermonuclear supernova explosions stable cellular flames develop around the Gibson scale and that deflagration-to-detonation transition is unlikely to be triggered from flame evolution effects here.

  10. File:USDA-CE-Production-GIFmaps-IA.pdf | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QAsource History View New Pages RecentTempCampApplicationWorksheet 2011.pdf JumpTransmission SitingFL.pdf JumpIA.pdf

  11. IA REP0 SAND85-2809 Unlimited Release UC-92A

    Office of Scientific and Technical Information (OSTI)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefield MunicipalTechnical Report:Speeding accessby aLED Street LightingFrom theHighI _ _ ORNL-6161 OAK*I.IA

  12. Type Ia supernovae yielding distances with 3-4% precision (Journal Article)

    Office of Scientific and Technical Information (OSTI)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.Theory of rare Kaon and(Conference) | SciTech(2D-CARS):| SciTech Connect Type Ia

  13. Type Ia supernovae yielding distances with 3-4% precision (Journal Article)

    Office of Scientific and Technical Information (OSTI)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.Theory of rare Kaon and(Conference) | SciTech(2D-CARS):| SciTech Connect Type Ia|

  14. Company City State Contact Info 21st Century Plastics Corporation Potterville MI www.21stcpc.com

    E-Print Network [OSTI]

    McGaughey, Alan

    Engineered Plastics, LLC Auburn Hills MI www.deltaengineeredplastics.com Detrex Corporation.dutchlandplastics.com E & O Tool & Plastics, Inc. Elk River MN www.eoplastics.com E & T Plastic Rubber & Plastics Corp. Farmington Hills MI www.exoticautomation.com F & D Plastics, Inc

  15. GaN: Defect and Device Issues

    SciTech Connect (OSTI)

    Pearton, S.J.; Ren, F.; Shul, R.J.; Zolper, J.C.

    1998-11-09

    The role of extended and point defects, and key impurities such as C, O and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

  16. Influence of pressure on photoluminescence and electroluminescence in GaN/InGaN/AlGaN quantum wells

    E-Print Network [OSTI]

    Weinstein, Benard.A.

    recently that the temperature shifts of the photo- and electroluminescence EL peak energies in Nichia greenV/GPa for the green and blue diodes, respectively. The observed pressure coefficients are much lower than those characteristic of the energy gap in GaN ( 40 meV/GPa) or the energy gap in InN ( 33 meV/GPa). This kind

  17. Roles of the MicroRNA miR-31 in tumor metastasis and an experimental system for the unbiased discovery of genes relevant for breast cancer metastasis

    E-Print Network [OSTI]

    Valastyan, Scott J. (Scott John)

    2010-01-01

    In these studies, the microRNA miR-31 was identified as a potent inhibitor of breast cancer metastasis. miR-31 expression levels were inversely associated with the propensity to develop metastatic disease in human breast ...

  18. InGaAs/GaAs quantum dot interdiffiusion induced by cap layer overgrowth

    SciTech Connect (OSTI)

    Jasinski, J.; Babinski, A.; Czeczott, M.; Bozek, R.

    2000-06-28

    The effect of thermal treatment during and after growth of InGaAs/GaAs quantum dot (QD) structures was studied. Transmission electron microscopy and atomic force microscopy confirmed the presence of interacting QDs, as was expected from analysis of temperature dependence of QD photoluminescence (PL) peak. The results indicate that the effect of post-growth annealing can be similar to the effect of elevated temperature of capping layer growth. Both, these thermal treatments can lead to a similar In and Ga interdiffiusion resulting in a similar blue-shift of QD PL peak.

  19. Optical spectroscopy of quantum confined states in GaAs/AlGaAs quantum well tubes

    SciTech Connect (OSTI)

    Shi, Teng; Fickenscher, Melodie; Smith, Leigh; Jackson, Howard; Yarrison-Rice, Jan; Gao, Qiang; Tan, Hoe; Jagadish, Chennupati; Etheridge, Joanne; Wong, Bryan M.

    2013-12-04

    We have investigated the quantum confinement of electronic states in GaAs/Al{sub x}Ga{sub 1?x}As nanowire heterostructures which contain radial GaAs quantum wells of either 4nm or 8nm. Photoluminescence and photoluminescence excitation spectroscopy are performed on single nanowires. We observed emission and excitation of electron and hole confined states. Numerical calculations of the quantum confined states using the detailed structural information on the quantum well tubes show excellent agreement with these optical results.

  20. TYCHO SN 1572: A NAKED Ia SUPERNOVA REMNANT WITHOUT AN ASSOCIATED AMBIENT MOLECULAR CLOUD

    SciTech Connect (OSTI)

    Tian, W. W.; Leahy, D. A.

    2011-03-10

    The historical supernova remnant (SNR) Tycho SN 1572 originates from the explosion of a normal Type Ia supernova that is believed to have originated from a carbon-oxygen white dwarf in a binary system. We analyze the 21 cm continuum, H I, and {sup 12}CO-line data from the Canadian Galactic Plane Survey in the direction of SN 1572 and the surrounding region. We construct H I absorption spectra to SN 1572 and three nearby compact sources. We conclude that SN 1572 has no molecular cloud interaction, which argues against previous claims that a molecular cloud is interacting with the SNR. This new result does not support a recent claim that dust, newly detected by AKARI, originates from such an SNR-cloud interaction. We suggest that the SNR has a kinematic distance of 2.5-3.0 kpc based on a nonlinear rotational curve model. Very high energy {gamma}-ray emission from the remnant has been detected by the VERITAS telescope, so our result shows that its origin should not be an SNR-cloud interaction. Both radio and X-ray observations support that SN 1572 is an isolated Type Ia SNR.

  1. Smoothed Particle Hydrodynamics simulations of the core-degenerate scenario for Type Ia supernovae

    E-Print Network [OSTI]

    Aznar-Siguán, G; Lorén-Aguilar, P; Soker, N; Kashi, A

    2015-01-01

    The core-degenerate (CD) scenario for type Ia supernovae (SN Ia) involves the merger of the hot core of an asymptotic giant branch (AGB) star and a white dwarf, and might contribute a non-negligible fraction of all thermonuclear supernovae. Despite its potential interest, very few studies, and based on only crude simplifications, have been devoted to investigate this possible scenario, compared with the large efforts invested to study some other scenarios. Here we perform the first three-dimensional simulations of the merger phase, and find that this process can lead to the formation of a massive white dwarf, as required by this scenario. We consider two situations, according to the mass of the circumbinary disk formed around the system during the final stages of the common envelope phase. If the disk is massive enough, the stars merge on a highly eccentric orbit. Otherwise, the merger occurs after the circumbinary disk has been ejected and gravitational wave radiation has brought the stars close to the Roche...

  2. Variable Selection for Modeling the Absolute Magnitude at Maximum of Type Ia Supernovae

    E-Print Network [OSTI]

    Uemura, Makoto; Kawabata, S; Ikeda, Shiro; Maeda, Keiichi

    2015-01-01

    We discuss what is an appropriate set of explanatory variables in order to predict the absolute magnitude at the maximum of Type Ia supernovae. In order to have a good prediction, the error for future data, which is called the "generalization error," should be small. We use cross-validation in order to control the generalization error and LASSO-type estimator in order to choose the set of variables. This approach can be used even in the case that the number of samples is smaller than the number of candidate variables. We studied the Berkeley supernova database with our approach. Candidates of the explanatory variables include normalized spectral data, variables about lines, and previously proposed flux-ratios, as well as the color and light-curve widths. As a result, we confirmed the past understanding about Type Ia supernova: i) The absolute magnitude at maximum depends on the color and light-curve width. ii) The light-curve width depends on the strength of Si II. Recent studies have suggested to add more va...

  3. Spectroscopic Observations and Analysis of the Unusual Type Ia SN1999ac

    SciTech Connect (OSTI)

    Garavini, G.; Aldering, G.; Amadon, A.; Amanullah, R.; Astier,P.; Balland, C.; Blanc, G.; Conley, A.; Dahlen, T.; Deustua, S.E.; Ellis,R.; Fabbro, S.; Fadeyev, V.; Fan, X.; Folatelli, G.; Frye, B.; Gates,E.L.; Gibbons, R.; Goldhaber, G.; Goldman, B.; Goobar, A.; Groom, D.E.; Haissinski, J.; Hardin, D.; Hook, I.; Howell, D.A.; Kent, S.; Kim, A.G.; Knop, R.A.; Kowalski, M.; Kuznetsova, N.; Lee, B.C.; Lidman, C.; Mendez,J.; Miller, G.J.; Moniez, M.; Mouchet, M.; Mourao, A.; Newberg, H.; Nobili, S.; Nugent, P.E.; Pain, R.; Perdereau, O.; Perlmutter, S.; Quimby, R.; Regnault, N.; Rich, J.; Richards, G.T.; Ruiz-Lapuente, P.; Schaefer, B.E.; Schahmaneche, K.; Smith, E.; Spadafora, A.L.; Stanishev,V.; Thomas, R.C.; Walton, N.A.; Wang, L.; Wood-Vasey, W.M.

    2005-07-12

    The authors present optical spectra of the peculiar Type Ia supernova (SN Ia) 1999ac. The data extend from -15 to +42 days with respect to B-band maximum and reveal an event that is unusual in several respects. prior to B-band maximum, the spectra resemble those of SN 1999aa, a slowly declining event, but possess stronger Si II and Ca II signatures (more characteristic of a spectroscopically normal SN). Spectra after B-band maximum appear more normal. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are higher than average. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are higher than average. The expansion velocities inferred from Si II are among the slowest ever observed, though SN 1999ac is not particularly dim. The analysis of the parameters v{sub 10}(Si II), R(Si II), v, and {Delta}m{sub 15} further underlines the unique characteristics of SN 1999ac. They find convincing evidence of C II {lambda}6580 in the day -15 spectrum with ejection velocity v > 16,000 km s{sup -1}, but this signature disappears by day -9. This rapid evolution at early times highlights the importance of extremely early-time spectroscopy.

  4. Consistent use of type Ia supernovae highly magnified by galaxy clusters to constrain the cosmological parameters

    SciTech Connect (OSTI)

    Zitrin, Adi [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Redlich, Matthias [Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Philosophenweg 12, D-69120 Heidelberg (Germany); Broadhurst, Tom, E-mail: adizitrin@gmail.com [Department of Theoretical Physics, University of Basque Country UPV/EHU, Bilbao (Spain)

    2014-07-01

    We discuss how Type Ia supernovae (SNe) strongly magnified by foreground galaxy clusters should be self-consistently treated when used in samples fitted for the cosmological parameters. While the cluster lens magnification of a SN can be well constrained from sets of multiple images of various background galaxies with measured redshifts, its value is typically dependent on the fiducial set of cosmological parameters used to construct the mass model. In such cases, one should not naively demagnify the observed SN luminosity by the model magnification into the expected Hubble diagram, which would create a bias, but instead take into account the cosmological parameters a priori chosen to construct the mass model. We quantify the effect and find that a systematic error of typically a few percent, up to a few dozen percent per magnified SN may be propagated onto a cosmological parameter fit unless the cosmology assumed for the mass model is taken into account (the bias can be even larger if the SN is lying very near the critical curves). We also simulate how such a bias propagates onto the cosmological parameter fit using the Union2.1 sample supplemented with strongly magnified SNe. The resulting bias on the deduced cosmological parameters is generally at the few percent level, if only few biased SNe are included, and increases with the number of lensed SNe and their redshift. Samples containing magnified Type Ia SNe, e.g., from ongoing cluster surveys, should readily account for this possible bias.

  5. Supercal: Cross-Calibration of Multiple Photometric Systems to Improve Cosmological Measurements with Type Ia Supernovae

    E-Print Network [OSTI]

    Scolnic, D; Riess, A G; Rest, A; Schlafly, E; Foley, R J; Finkbeiner, D; Tang, C; Burgett, W S; Chambers, K C; Draper, P W; Hodapp, K W; Huber, M E; Kaiser, N; Kudritzki, R P; Magnier, E A; Metcalfe, N; Stubbs, C W

    2015-01-01

    Current cosmological analyses which use Type Ia supernova (SN Ia) observations combine SN samples to expand the redshift range beyond that of a single sample and increase the overall sample size. The inhomogeneous photometric calibration between different SN samples is one of the largest systematic uncertainties of the cosmological parameter estimation. To place these different samples on a single system, analyses currently use observations of a small sample of very bright flux standards on the $HST$ system. We propose a complementary method, called `Supercal', in which we use measurements of secondary standards in each system, compare these to measurements of the same stars in the Pan-STARRS1 (PS1) system, and determine offsets for each system relative to PS1, placing all SN observations on a single, consistent photometric system. PS1 has observed $3\\pi$ of the sky and has a relative calibration of better than 5 mmag (for $\\sim15

  6. Convection during the Late Stages of Simmering in Type Ia Supernovae

    E-Print Network [OSTI]

    Piro, Anthony L

    2008-01-01

    Following unstable ignition of carbon, but prior to explosion, a white dwarf (WD) in a Type Ia supernova (SN Ia) undergoes a simmering phase. During this time, a central convective region grows and encompasses ~1 Msun of the WD over a timescale of ~1000 yrs, which sets the thermal and turbulent profile for the subsequent explosion. We study this time-dependent convection and summarize some of the key features that differ from the traditional, steady-state case. We show that the long conductive timescale above the convective zone and the extraction of energy to heat the WD core leads to a decrease of the convective luminosity and characteristic velocities near the convective zone's top boundary. In addition, differences in the composition between the convective core and the conductive exterior will significantly alter the location of this boundary. In this respect, we find the biggest effect due to complete 22Ne sedimentation prior to carbon ignition. These effects add diversity to the possible WD models, whic...

  7. Spectroscopic Determination of the Low Redshift Type Ia Supernova Rate from the Sloan Digital Sky Survey

    SciTech Connect (OSTI)

    Krughoff, K. S.; Connolly, Andrew J.; Frieman, Joshua; SubbaRao, Mark; Kilper, Gary; Schneider, Donald P.

    2011-04-10

    Supernova rates are directly coupled to high mass stellar birth and evolution. As such, they are one of the few direct measures of the history of cosmic stellar evolution. In this paper we describe an probabilistic technique for identifying supernovae within spectroscopic samples of galaxies. We present a study of 52 type Ia supernovae ranging in age from -14 days to +40 days extracted from a parent sample of \\simeq 50,000 spectra from the SDSS DR5. We find a Supernova Rate (SNR) of 0.472^{+0.048}_{-0.039}(Systematic)^{+0.081}_{-0.071}(Statistical)SNu at a redshift of = 0.1. This value is higher than other values at low redshift at the 1{\\sigma}, but is consistent at the 3{\\sigma} level. The 52 supernova candidates used in this study comprise the third largest sample of supernovae used in a type Ia rate determination to date. In this paper we demonstrate the potential for the described approach for detecting supernovae in future spectroscopic surveys.

  8. First Evidence of Globular Cluster Formation from the Ejecta of Prompt Type Ia Supernovae

    E-Print Network [OSTI]

    Tsujimoto, Takuji

    2012-01-01

    Recent spectroscopic observations of globular clusters (GCs) in the Large Magellanic Cloud (LMC) have discovered that one of the intermediate-age GC, NGC 1718 with [Fe/H]=-0.7 has an extremely low [Mg/Fe] ratio of ~-0.9. We propose that NGC 1718 was formed from the ejecta of type Ia supernovae (SNe Ia) mixed with very metal-poor ([Fe/H] <-1.3) gas about ~ 2 Gyr ago. The proposed scenario is shown to be consistent with the observed abundances of Fe-group elements such as Cr, Mn, and Ni. In addition, compelling evidence for asymptotic giant branch stars playing a role in chemical enrichment during this GC formation is found. We suggest that the origin of the metal-poor gas is closely associated with the efficient gas-transfer from the outer gas disk of the Small Magellanic Cloud to the LMC disk. We anticipate that the outer part of the LMC disk contains field stars exhibiting significantly low [Mg/Fe] ratios, formed through the same process as NGC 1718.

  9. Structural and optical properties of InGaN–GaN nanowire heterostructures grown by molecular beam epitaxy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Limbach, F.; Gotschke, T.; Stoica, T.; Calarco, R.; Sutter, E.; Ciston, J.; Cusco, R.; Artus, L.; Kremling, S.; Ho?fling, S.; et al

    2011-01-01

    InGaN/GaN nanowire (NW) heterostructures grown by plasma assisted molecular beam epitaxy were studied in comparison to their GaN and InGaN counterparts. The InGaN/GaN heterostructure NWs are composed of a GaN NW, a thin InGaN shell, and a multifaceted InGaN cap wrapping the top part of the GaN NW. High-resolution transmission electron microscopy (HRTEM) images taken from different parts of a InGaN/GaN NW show a wurtzite structure of the GaN core and the epitaxial InGaN shell around it, while additional crystallographic domains are observed whithin the InGaN cap region. Large changes in the lattice parameter along the wire, from pure GaNmore »to higher In concentration demonstrate the successful growth of a complex InGaN/GaN NW heterostructure. Photoluminescence (PL) spectra of these heterostructure NW ensembles show rather broad and intense emission peak at 2.1 eV. However, ?-PL spectra measured on single NWs reveal a reduced broadening of the visible luminescence. The analysis of the longitudinal optical phonon Raman peak position and its shape reveal a variation in the In content between 20% and 30%, in agreement with the values estimated by PL and HRTEM investigations. The reported studies are important for understanding of the growth and properties of NW heterostructures suitable for applications in optoelectronics and photovoltaics.« less

  10. Reprinted from the Proceedings of the 1998 ASEE North Central Section Meeting, University of Detroit Mercy, Detroit, MI, April 3-4, 1998. ( Best Paper Award )

    E-Print Network [OSTI]

    Bell, John T.

    of Detroit Mercy, Detroit, MI, April 3-4, 1998. ( Best Paper Award ) VIRTUAL REALITY IN CHEMICAL ENGINEERING

  11. BENDIX SYSTEMS DIVISION ANN AIt 1 o I, MI CH NO. Plan for Operational Contingency

    E-Print Network [OSTI]

    Rathbun, Julie A.

    8/29/66 BENDIX SYSTEMS DIVISION ANN AIt 1 o I, MI CH NO. ATM-396 Plan for Operational Contingency of the operational plans and the system design and to study methods of recovery from partial failure through the use. ATM- 396 RIV.MO. A I I f..r I (I IOperational Contingency Study 2 PAGI OP

  12. New Loops! MiTeGen* 50MicroMountsTM consist of a thin microfabricated

    E-Print Network [OSTI]

    Meagher, Mary

    New Loops! MiTeGen* 50µMicroMountsTM consist of a thin microfabricated polyimide film attached to a solid non-magnetic stainless steel pin. The film is polyimide, which is used in Kapton® tape and is employed for X- ray transparent windows on X-ray beam lines. The film is curved by wrapping polyimide film

  13. 2000 JAPAN-USA Symposium on Flexible Automation July 23-26, 2000, Ann Arbor, MI

    E-Print Network [OSTI]

    Saitou, Kazuhiro "Kazu"

    2000 JAPAN-USA Symposium on Flexible Automation July 23-26, 2000, Ann Arbor, MI 2000JUSFA-US1 OFF-LINE ERROR RECOVERY LOGIC SYNTHESIS IN AUTOMATED ASSEMBLY LINES BY USING GENETIC PROGRAMMING Cem M. Baydar by the experts or automated error recovery logic controllers embedded in the system. The previous work

  14. An HNF4a-miRNA Inflammatory Feedback Circuit Regulates

    E-Print Network [OSTI]

    An HNF4a-miRNA Inflammatory Feedback Circuit Regulates Hepatocellular Oncogenesis Maria, once this circuit is activated, it maintains suppression of HNF4a and sustains oncogenesis. Systemic recapitulate hepatic oncogenesis in various animal models (He et al., 2010). In addition, the inflammatory

  15. AUSTRALIAN. N~TIONAL UNIVE~SITY DEPARTMENTO:miNUCLEAR PFf-y'SICS

    E-Print Network [OSTI]

    Chen, Ying

    AUSTRALIAN. N~TIONAL UNIVE~SITY DEPARTMENTO:miNUCLEAR PFf-y'SICS 14UD TANK OPENING REPORT/iNo. 51 functions for which it provides power. An order was . immediately placed with N.E.C. for 28 perspex bars microamp hours of b.d.p. generation than its predicted lifetime. In preparation for the next opening

  16. MSU CENTER FOR REGIONAL FOOD SYSTEMS 480 WILSON ROAD, EAST LANSING, MI 48824

    E-Print Network [OSTI]

    AN ANNOTATED BIBLIOGRAPHY ON STRUCTURAL RACISM PRESENT IN THE U.S. FOOD SYSTEM JUNE 2015 #12;Michigan State University Center for Regional Food Systems Structural Racism Present in the U.S. Food System 2 AUTHORS Anel on structural racism present in the U.S. food system. East Lansing, MI: MSU Center for Regional Food Systems

  17. Request for Alternative Activity for PLI Credit Last Name First Name M.I.

    E-Print Network [OSTI]

    Connors, Daniel A.

    Request for Alternative Activity for PLI Credit Full Name: Last Name First Name M.I. Email Address information for Coordinator of Program: Requesting Alternate Activity credit for which PLI Track (Choose one): Verification Information Email Address: College of Engineering Student Information Alternate Activity

  18. MI FARM TO SCHOOL GRANTEES 2014-2015 PROGRAM YEAR AND PREVIOUS GRANTEES

    E-Print Network [OSTI]

    MI FARM TO SCHOOL GRANTEES 2014-2015 PROGRAM YEAR AND PREVIOUS GRANTEES FOODSYSTEMS.MSU.EDU 2014-2015 GRANTEES School/ district/ program County Current Grant Years as a grantee A&W Daycare Wayne Planning 1 TO SCHOOL GRANTEES (2011/12 ­ 2013/14) School/ district/ program County Grant Type(s) Grant Years All Aboard

  19. IEEE Energy2030 Atlanta, GA USA

    E-Print Network [OSTI]

    Gross, George

    of an aggregation of battery vehicles for the provision of frequency regulation ­ requiring very fast response timesIEEE Energy2030 Atlanta, GA USA 17-18 November, 2008 Design of a Conceptual Framework for the V2G in common is the batteries, which provide good storage capacity that can be effectively integrated

  20. 495 Tech Way NW Atlanta, GA 30318

    E-Print Network [OSTI]

    Li, Mo

    495 Tech Way NW Atlanta, GA 30318 404.385.0384 comments@energy.gatech.edu Copyright 2014 · Georgia concerns, low-cost, clean, secure energy solutions will be necessary to address our global energy needs and sustain our way of life. Georgia Tech Energy Innovations The Strategic Energy Institute's scientists

  1. Defect studies in low-temperature-grown GaAs

    SciTech Connect (OSTI)

    Bliss, D.E.

    1992-11-01

    High content of excess As is incorporated in GaAs grown by low-temperature molecular-beam-epitaxy (LTMBE). The excess As exists primarily as As antisite defects AsGa and a lesser extent of gallium vacancies V[sub Ga]. The neutral AsGa-related defects were measured by infrared absorption at 1[mu]m. Gallium vacancies, V[sub Ga], was investigated by slow positron annihilation. Dependence of defect contents on doping was studied by Si and Be dopants. No free carriers are generated by n-type or p-type doping up to 10[sup 19] cm[sup [minus]3] Si or Be. Raman data indicate Be occupies Ga substitutional sites but Si atom is not substitutional. Si induces more As[sub Ga] in the layer. As As[sub Ga] increases, photoquenchable As[sub Ga] decreases. Fraction of photoquenchable defects correlates to defects within 3 nearest neighbor separations disrupting the metastability. Annealing reduces neutral As[sub Ga] content around 500C, similar to irradiation damaged and plastically deformed Ga[sub As], as opposed to bulk grown GaAs in which As[sub Ga]-related defects are stable up to 1100C. The lower temperature defect removal is due to V[sub Ga] enhanced diffusion of As[sub Ga] to As precipitates. The supersaturated V[sub GA] and also decreases during annealing. Annealing kinetics for As[sub Ga]-related defects gives 2.0 [plus minus] 0.3 eV and 1.5 [plus minus] 0.3 eV migration enthalpies for the As[sub Ga] and V[sub Ga]. This represents the difference between Ga and As atoms hopping into the vacancy. The non-photoquenchable As[sub Ga]-related defects anneal with an activation energy of 1.1 [plus minus] 0.3eV. Be acceptors can be activated by 800C annealing. Temperature difference between defect annealing and Be activation formation of As[sub Ga]-Be[sub Ga] pairs. Si donors can only be partially activated.

  2. Electron mobility enhancement in AlN/GaN/AlN heterostructures with InGaN nanogrooves

    E-Print Network [OSTI]

    it was discovered by Davydov et al.1 and con- firmed by independent studies2,3 that its band gap is small, EG InN =0 The conduction band offset at GaN/AlN interface was estimated as EQW=0.7 EG AlN -EG GaN =1918 meV. The nanoN/GaN/AlN QW. The depth of the nanogroove is calculated as E0=0.8 EG GaN -EG InxGa1-xN . The band gap of InxGa1

  3. Polyphenol-induced Anti-inflammatory and Cytotoxic Activities in Breast and Colon Cancer: Potential Role of miRNA's in Cell Survival and Inflammation 

    E-Print Network [OSTI]

    Banerjee, Nivedita

    2013-12-11

    growth in athymic BALB/c nude mice with BT474 xenografts. Interactions of Pg with miR-27a- ZBTB10-Sp and miR-155-SHIP-1-PI3K axes and mango miR126/PI3K/AKT axis were identified. In addition, pomegranate and plum polyphenols exerted cytotoxic and anti...

  4. SAE 1983 Transactions, Paper No. 830200, pp. 1.810-1.816 International Congress & Exposition, Detroit, Mi., Feb. 28-March 4, 1983

    E-Print Network [OSTI]

    Radcliffe, Clark J.

    , Detroit, Mi., Feb. 28- March 4, 1983 #12;SAE 1983 Transactions, Paper No. 830200, pp. 1.810-1.816 International Congress & Exposition, Detroit, Mi., Feb. 28- March 4, 1983 #12;SAE 1983 Transactions, Paper No. 830200, pp. 1.810-1.816 International Congress & Exposition, Detroit, Mi., Feb. 28- March 4, 1983 Fig. 2

  5. A Generalized {ital K} Correction for Type Ia Supernovae: Comparing {ital R}-band Photometry Beyond {ital z=9.2} with B,V, and {ital R}-band Nearby Photometry

    E-Print Network [OSTI]

    Goodbar, Ariel

    2008-01-01

    spectroscopically peculiar supernovae, and to search for anyK Correction for Type Ia Supernovae: Comparing R-bandK Correction for Type Ia Supernovae: Comparing R-band

  6. Development and Industrialization of InGaN/GaN LEDs on Patterned...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    epitaxial growth of indium gallium nitride (InGaN) layers capable of producing high-efficiency LEDs when combined with chip-on-board packaging techniques. The proposed...

  7. High-field quasi-ballistic transport in AlGaN/GaN heterostructures

    SciTech Connect (OSTI)

    Danilchenko, B. A.; Tripachko, N. A.; Belyaev, A. E.; Vitusevich, S. A. Hardtdegen, H.; Lüth, H.

    2014-02-17

    Mechanisms of electron transport formation in 2D conducting channels of AlGaN/GaN heterostructures in extremely high electric fields at 4.2?K have been studied. Devices with a narrow constriction for the current flow demonstrate high-speed electron transport with an electron velocity of 6.8?×?10{sup 7}?cm/s. Such a velocity is more than two times higher than values reported for conventional semiconductors and about 15% smaller than the limit value predicted for GaN. Superior velocity is attained in the channel with considerable carrier reduction. The effect is related to a carrier runaway phenomenon. The results are in good agreement with theoretical predictions for GaN-based materials.

  8. 2DEG electrodes for piezoelectric transduction of AlGaN/GaN MEMS resonators

    E-Print Network [OSTI]

    Weinstein, Dana

    A 2D electron gas (2DEG) interdigitated transducer (IDT) in Gallium Nitride (GaN) resonators is introduced and demonstrated. This metal-free transduction does not suffer from the loss mechanisms associated with more commonly ...

  9. Emission and Excitation Spectra of ZnO:Ga and ZnO:Ga,N Ceramics

    E-Print Network [OSTI]

    P. A. Rodnyi; I. V. Khodyuk; E. I. Gorokhova; S. B. Mikhrin; P. Dorenbos

    2010-09-07

    The spectral characteristics of ZnO:Ga and ZnO:Ga,N ceramics prepared by uniaxial hot pressing have been investigated. At room temperature, the edge (exciton) band at 3.12 eV dominates in the luminescence spectra of ZnO:Ga, while a wide luminescence band at 2.37 eV, which is likely to be due to zinc vacancies, is observed in the spectra of ZnO:Ga,N. Upon heating, the edge band maximum shifts to lower energies and the bandwidth increases. The extrapolated position of the edge-band maximum at zero temperature, Em(0) = 3.367 +/- 0.005 eV, is in agreement with the data for thin zinc oxide films. The luminescence excitation spectra in the range from 3 to 6.5 eV are reported and the mechanism of energy transfer to excitons and luminescence centers is considered.

  10. Composition profiling of GaAs/AlGaAs quantum dots grown by droplet epitaxy

    SciTech Connect (OSTI)

    Bocquel, J.; Koenraad, P. M. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Giddings, A. D.; Prosa, T. J.; Larson, D. J. [CAMECA Instruments, Inc., 5500 Nobel Drive, Madison, Wisconsin 53711 (United States); Mano, T. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2014-10-13

    Droplet epitaxy (DE) is a growth method which can create III-V quantum dots (QDs) whose optoelectronic properties can be accurately controlled through the crystallisation conditions. In this work, GaAs/AlGaAs DE-QDs have been analyzed with the complimentary techniques of cross-sectional scanning tunneling microscopy and atom probe tomography. Structural details and a quantitative chemical analysis of QDs of different sizes are obtained. Most QDs were found to be pure GaAs, while a small proportion exhibited high intermixing caused by a local etching process. Large QDs with a high aspect ratio were observed to have an Al-rich crown above the GaAs QD. This structure is attributed to differences in mobility of the cations during the capping phase of the DE growth.

  11. MiR-18a regulates the proliferation, migration and invasion of human glioblastoma cell by targeting neogenin

    SciTech Connect (OSTI)

    Song, Yichen; Wang, Ping; Zhao, Wei; Yao, Yilong; Liu, Xiaobai; Ma, Jun; Xue, Yixue; Liu, Yunhui

    2014-05-15

    MiR-17-92 cluster has recently been reported as an oncogene in some tumors. However, the association of miR-18a, an important member of this cluster, with glioblastoma remains unknown. Therefore, this study aims to investigate the expression of miR-18a in glioblastoma and its role in biological behavior of U87 and U251 human glioblastoma cell lines. Quantitative RT-PCR results showed that miR-18a was highly expressed in glioblastoma tissues and U87 and U251 cell lines compared with that in human brain tissues and primary normal human astrocytes, and the expression levels were increased along with the rising pathological grades of glioblastoma. Neogenin was identified as the target gene of miR-18a by dual-luciferase reporter assays. RT-PCR and western blot results showed that its expression levels were decreased along with the rising pathological grades of glioblastoma. Inhibition of miR-18a expression was established by transfecting exogenous miR-18a inhibitor into U87 and U251 cells, and its effects on the biological behavior of glioblastoma cells were studied using CCK-8 assay, transwell assay and flow cytometry. Inhibition of miR-18a expression in U87 and U251 cells significantly up-regulated neogenin, and dramatically suppressed the abilities of cell proliferation, migration and invasion, induced cell cycle arrest and promoted cellular apoptosis. Collectively, these results suggest that miR-18a may regulate biological behavior of human glioblastoma cells by targeting neogenin, and miR-18a can serve as a potential target in the treatment of glioblastoma. - Highlights: • MiR-18a was highly expressed in glioblastoma tissues and U87 and U251 cell lines. • Neogenin was identified as the target gene of miR-18a. • Neogenin expressions were decreased along with the rising pathological grades of glioblastoma. • Inhibition of miR-18a suppressed biological behavior of glioma cells by up-regulating neogenin.

  12. On strongly GA-convex functions and stochastic processes

    SciTech Connect (OSTI)

    Bekar, Nurgül Okur; Akdemir, Hande Günay; ??can, ?mdat

    2014-08-20

    In this study, we introduce strongly GA-convex functions and stochastic processes. We provide related well-known Kuhn type results and Hermite-Hadamard type inequality for strongly GA-convex functions and stochastic processes.

  13. Energy absorption in Ni-Mn-Ga/ polymer composites

    E-Print Network [OSTI]

    Feuchtwanger, Jorge

    2006-01-01

    In recent years Ni-Mn-Ga has attracted considerable attention as a new kind of actuator material. Off-stoichiometric single crystals of Ni2MnGa can regularly exhibit 6% strain in tetragonal martensites and orthorhombic ...

  14. InGaAs/GaAs (110) quantum dot formation via step meandering

    SciTech Connect (OSTI)

    Diez-Merino, Laura; Tejedor, Paloma

    2011-07-01

    InGaAs (110) semiconductor quantum dots (QDs) offer very promising prospects as a material base for a new generation of high-speed spintronic devices, such as single electron transistors for quantum computing. However, the spontaneous formation of InGaAs QDs is prevented by two-dimensional (2D) layer-by-layer growth on singular GaAs (110) substrates. In this work we have studied, by using atomic force microscopy and photoluminescence spectroscopy (PL), the growth of InGaAs/GaAs QDs on GaAs (110) stepped substrates by molecular beam epitaxy (MBE), and the modification of the adatom incorporation kinetics to surface steps in the presence of chemisorbed atomic hydrogen. The as-grown QDs exhibit lateral dimensions below 100 nm and emission peaks in the 1.35-1.37 eV range. It has been found that a step meandering instability derived from the preferential attachment of In adatoms to [110]-step edges relative to [11n]-type steps plays a key role in the destabilization of 2D growth that leads to 3D mound formation on both conventional and H-terminated vicinal substrates. In the latter case, the driving force for 3D growth via step meandering is enhanced by H-induced upward mass transport in addition to the lower energy cost associated with island formation on H-terminated substrates, which results in a high density array of InGaAs/GaAs dots selectively nucleated on the terrace apices with reduced lateral dimensions and improved PL efficiency relative to those of conventional MBE-grown samples.

  15. Sheet resistance under Ohmic contacts to AlGaN/GaN heterostructures

    SciTech Connect (OSTI)

    Haj?asz, M., E-mail: m.hajlasz@m2i.nl [Materials innovation institute (M2i), Mekelweg 2, 2628 CD, Delft (Netherlands); MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede (Netherlands); Donkers, J. J. T. M.; Sque, S. J.; Heil, S. B. S. [NXP Semiconductors Research, High Tech Campus 46, 5656 AE, Eindhoven (Netherlands); Gravesteijn, D. J. [NXP Semiconductors Research, High Tech Campus 46, 5656 AE, Eindhoven (Netherlands); MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede (Netherlands); Rietveld, F. J. R. [NXP Semiconductors, Gerstweg 2, 6534 AE, Nijmegen (Netherlands); Schmitz, J. [MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede (Netherlands)

    2014-06-16

    For the determination of specific contact resistance in semiconductor devices, it is usually assumed that the sheet resistance under the contact is identical to that between the contacts. This generally does not hold for contacts to AlGaN/GaN structures, where an effective doping under the contact is thought to come from reactions between the contact metals and the AlGaN/GaN. As a consequence, conventional extraction of the specific contact resistance and transfer length leads to erroneous results. In this Letter, the sheet resistance under gold-free Ti/Al-based Ohmic contacts to AlGaN/GaN heterostructures on Si substrates has been investigated by means of electrical measurements, transmission electron microscopy, and technology computer-aided design simulations. It was found to be significantly lower than that outside of the contact area; temperature-dependent electrical characterization showed that it exhibits semiconductor-like behavior. The increase in conduction is attributed to n-type activity of nitrogen vacancies in the AlGaN. They are thought to form during rapid thermal annealing of the metal stack when Ti extracts nitrogen from the underlying semiconductor. The high n-type doping in the region between the metal and the 2-dimensional electron gas pulls the conduction band towards the Fermi level and enhances horizontal electron transport in the AlGaN. Using this improved understanding of the properties of the material underneath the contact, accurate values of transfer length and specific contact resistance have been extracted.

  16. AlGaAs/GaAs photovoltaic converters for high power narrowband radiation

    SciTech Connect (OSTI)

    Khvostikov, Vladimir; Kalyuzhnyy, Nikolay; Mintairov, Sergey; Potapovich, Nataliia; Shvarts, Maxim; Sorokina, Svetlana; Andreev, Viacheslav; Luque, Antonio

    2014-09-26

    AlGaAs/GaAs-based laser power PV converters intended for operation with high-power (up to 100 W/cm{sup 2}) radiation were fabricated by LPE and MOCVD techniques. Monochromatic (? = 809 nm) conversion efficiency up to 60% was measured at cells with back surface field and low (x = 0.2) Al concentration 'window'. Modules with a voltage of 4 V and the efficiency of 56% were designed and fabricated.

  17. Guided Neuronal Growth on Arrays of Biofunctionalized GaAs/InGaAs Semiconductor Microtubes

    E-Print Network [OSTI]

    Cornelius S. Bausch; Aune Koitmäe; Eric Stava; Amanda Price; Pedro J. Resto; Yu Huang; David Sonnenberg; Yuliya Stark; Christian Heyn; Justin C. Williams; Erik W. Dent; Robert H. Blick

    2013-05-06

    We demonstrate embedded growth of cortical mouse neurons in dense arrays of semiconductor microtubes. The microtubes, fabricated from a strained GaAs/InGaAs heterostructure, guide axon growth through them and enable electrical and optical probing of propagating action potentials. The coaxial nature of the microtubes -- similar to myelin -- is expected to enhance the signal transduction along the axon. We present a technique of suppressing arsenic toxicity and prove the success of this technique by overgrowing neuronal mouse cells.

  18. miR-7 and miR-218 epigenetically control tumor suppressor genes RASSF1A and Claudin-6 by targeting HoxB3 in breast cancer

    SciTech Connect (OSTI)

    Li, Qiaoyan; Zhu, Fufan; Chen, Puxiang

    2012-07-20

    Highlights: Black-Right-Pointing-Pointer Both miR-7 and miR-218 down-regulates HoxB3 expression by targeting the 3 Prime -UTR of HoxB3 mRNA. Black-Right-Pointing-Pointer A reverse correlation between the levels of endogenous miR-7, miR218 and HoxB3 expression. Black-Right-Pointing-Pointer Epigenetic changes involve in the reactivation of HoxB3. Black-Right-Pointing-Pointer Both miRNAs inhibits the cell cycle and clone formation of breast cancer cells. -- Abstract: Many microRNAs have been implicated as key regulators of cellular growth and differentiation and have been found to dysregulate proliferation in human tumors, including breast cancer. Cancer-linked microRNAs also alter the epigenetic landscape by way of DNA methylation and post-translational modifications of histones. Aberrations in Hox gene expression are important for oncogene or tumor suppressor during abnormal development and malignancy. Although recent studies suggest that HoxB3 is critical in breast cancer, the putative role(s) of microRNAs impinging on HoxB3 is not yet fully understood. In this study, we found that the expression levels of miR-7 and miR-218 were strongly and reversely associated with HoxB3 expression. Stable overexpression of miR-7 and miR-218 was accompanied by reactivation of tumor suppressor genes including RASSF1A and Claudin-6 by means of epigenetic switches in DNA methylation and histone modification, giving rise to inhibition of the cell cycle and clone formation of breast cancer cells. The current study provides a novel link between overexpression of collinear Hox genes and multiple microRNAs in human breast malignancy.

  19. Lateral and Vertical Transistors Using the AlGaN/GaN Heterostructure

    SciTech Connect (OSTI)

    Chowdhury, S; Mishra, UK

    2013-10-01

    Power conversion losses are endemic in all areas of electricity consumption, including motion control, lighting, air conditioning, and information technology. Si, the workhorse of the industry, has reached its material limits. Increasingly, the lateral AlGaN/GaN HEMT based on gallium nitride (GaN-on-Si) is becoming the device of choice for medium power electronics as it enables high-power conversion efficiency and reduced form factor at attractive pricing for wide market penetration. The reduced form factor enabled by high-efficiency operation at high frequency further enables significant system price reduction because of savings in bulky extensive passive elements and heat sink costs. The high-power market, however, still remains unaddressed by lateral GaN devices. The current and voltage demand for high power conversion application makes the chip area in a lateral topology so large that it becomes more difficult to manufacture. Vertical GaN devices would play a big role alongside of silicon carbide (SiC) to address the high power conversion needs. In this paper, the development, performance, and status of lateral and vertical GaN devices are discussed.

  20. GaNPAs Solar Cells Lattice-Matched To GaP: Preprint

    SciTech Connect (OSTI)

    Geisz, J. F.; Friedman, D. J.; Kurtz, S.

    2002-05-01

    This conference paper describes the III-V semiconductors grown on silicon substrates are very attractive for lower-cost, high-efficiency multijunction solar cells, but lattice-mismatched alloys that result in high dislocation densities have been unable to achieve satisfactory performance. GaNxP1-x-yAsy is a direct-gap III-V alloy that can be grown lattice-matched to Si when y= 4.7x - 0.1. We propose the use of lattice-matched GaNPAs on silicon for high-efficiency multijunction solar cells. We have grown GaNxP1-x-yAsy on GaP (with a similar lattice constant to silicon) by metal-organic chemical vapor phase epitaxy with direct band-gaps in the range of 1.5 to 2.0 eV. We demonstrate the performance of single-junction GaNxP1-x-yAsy solar cells grown on GaP substrates and discuss the prospects for the development of monolithic high-efficiency multijunction solar cells based on silicon substrates.

  1. Accurate characterization and improvement of GaAs microstrip attenuation 

    E-Print Network [OSTI]

    Carroll, James Mason

    1992-01-01

    Convergence. III. E. 6 Final Model. III. F Simulation Results for 100 um GaAs. . III. F. 1 On-GaAs Microstrip. III. I', 2 Suspended Microstrip Line . . . . 50 . . . . 51 . . . . 54 . . . . 56 . . . . 56 . . . 56 . . . . 64 64 . . . , 64 III. F. 3... Comparison Between On-GaAs and Suspcndcd Microstrip . . . 68 III. F. 4 Microstrip Inductance III. G EM Parameters in CAD Simulations . . III. H Simulation Results for 150 um GaAs. III. I Conclusions and Recommendations. IV RESEARCH ACCOMPLISHMENTS...

  2. Advanced technologies for improving high frequency performance of AlGaN/GaN high electron mobility transistors

    E-Print Network [OSTI]

    Chung, Jinwook W. (Jinwook Will)

    2008-01-01

    In this thesis, we have used a combination of physical analysis, numerical simulation and experimental work to identify and overcome some of the main challenges in AlGaN/GaN high electron mobility transistors (HEMTs) for ...

  3. LATE-TIME SPECTRAL OBSERVATIONS OF THE STRONGLY INTERACTING TYPE Ia SUPERNOVA PTF11kx

    SciTech Connect (OSTI)

    Silverman, Jeffrey M. [Department of Astronomy, University of Texas, Austin, TX 78712-0259 (United States); Nugent, Peter E.; Filippenko, Alexei V.; Cenko, S. Bradley [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Gal-Yam, Avishay [Benoziyo Center for Astrophysics, The Weizmann Institute of Science, Rehovot 76100 (Israel); Sullivan, Mark [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Howell, D. Andrew [Las Cumbres Observatory Global Telescope Network, Goleta, CA 93117 (United States); Pan, Yen-Chen; Hook, Isobel M., E-mail: jsilverman@astro.as.utexas.edu [Department of Physics (Astrophysics), University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom)

    2013-08-01

    PTF11kx was a Type Ia supernova (SN Ia) that showed time-variable absorption features, including saturated Ca II H and K lines that weakened and eventually went into emission. The strength of the emission component of H{alpha} gradually increased, implying that the SN was undergoing significant interaction with its circumstellar medium (CSM). These features, and many others, were blueshifted slightly and showed a P-Cygni profile, likely indicating that the CSM was directly related to, and probably previously ejected by, the progenitor system itself. These and other observations led Dilday et al. to conclude that PTF11kx came from a symbiotic nova progenitor like RS Oph. In this work we extend the spectral coverage of PTF11kx to 124-680 rest-frame days past maximum brightness. The late-time spectra of PTF11kx are dominated by H{alpha} emission (with widths of full width at half-maximum intensity Almost-Equal-To 2000 km s{sup -1}), strong Ca II emission features ({approx}10,000 km s{sup -1} wide), and a blue 'quasi-continuum' due to many overlapping narrow lines of Fe II. Emission from oxygen, He I, and Balmer lines higher than H{alpha} is weak or completely absent at all epochs, leading to large observed H{alpha}/H{beta} intensity ratios. The H{alpha} emission appears to increase in strength with time for {approx}1 yr, but it subsequently decreases significantly along with the Ca II emission. Our latest spectrum also indicates the possibility of newly formed dust in the system as evidenced by a slight decrease in the red wing of H{alpha}. During the same epochs, multiple narrow emission features from the CSM temporally vary in strength. The weakening of the H{alpha} and Ca II emission at late times is possible evidence that the SN ejecta have overtaken the majority of the CSM and agrees with models of other strongly interacting SNe Ia. The varying narrow emission features, on the other hand, may indicate that the CSM is clumpy or consists of multiple thin shells.

  4. A New Combustion Synthesis Method for GaN:Eu3+ and Ga2O3 :Eu3+

    E-Print Network [OSTI]

    McKittrick, Joanna

    A New Combustion Synthesis Method for GaN:Eu3+ and Ga2O3 :Eu3+ Luminescent Powders G. A. Hirata1 between the precursors. The preparation of Eu-doped Ga2O3 powders was achieved using a new combustion)3 and Ga(NO3)3 as the precursors and hydrazine as (non-carbonaceous) fuel. A spontaneous combustion

  5. The ESO/VLT 3rd year Type Ia supernova data set from the Supernova Legacy Survey

    E-Print Network [OSTI]

    Balland, C; Basa, S; Mouchet, M; Howell, D A; Astier, P; Carlberg, R G; Conley, A; Fouchez, D; Guy, J; Hardin, D; Hook, I M; Pain, R; Perrett, K; Pritchet, C J; Regnault, N; Rich, J; Sullivan, M; Antilogus, P; Arsenijevic, V; Du, J Le; Fabbro, S; Lidman, C; Mourao, A; Palanque-Delabrouille, Nathalie; Pécontal, E; Ruhlmann-Kleider, V

    2009-01-01

    We present 139 spectra of 124 Type Ia supernovae (SNeIa) that were observed at the ESO/VLT during the first three years of the Canada-France-Hawai Telescope (CFHT) Supernova Legacy Survey (SNLS). This homogeneous data set is used to test for redshift evolution of SNeIa spectra, and will be used in the SNLS 3rd year cosmological analyses. Spectra have been reduced and extracted with a dedicated pipeline that uses photometric information from deep CFHT Legacy Survey (CFHT-LS) reference images to trace, at sub-pixel accuracy, the position of the supernova on the spectrogram as a function of wavelength. It also separates the supernova and its host light in 60% of cases. The identification of the supernova candidates is performed using a spectrophotometric SNIa model. A total of 124 SNeIa, roughly 50% of the overall SNLS spectroscopic sample, have been identified using the ESO/VLT during the first three years of the survey. Their redshifts range from z=0.149 to z=1.031. The average redshift of the sample is z=0.63...

  6. The Joint Efficient Dark-energy Investigation (JEDI): Measuring the cosmic expansion history from type Ia supernovae

    E-Print Network [OSTI]

    M. M. Phillips; Peter Garnavich; Yun Wang; David Branch; Edward Baron; Arlin Crotts; J. Craig Wheeler; Edward Cheng; Mario Hamuy; for the JEDI Team

    2006-06-28

    JEDI (Joint Efficient Dark-energy Investigation) is a candidate implementation of the NASA-DOE Joint Dark Energy Mission (JDEM). JEDI will probe dark energy in three independent methods: (1) type Ia supernovae, (2) baryon acoustic oscillations, and (3) weak gravitational lensing. In an accompanying paper, an overall summary of the JEDI mission is given. In this paper, we present further details of the supernova component of JEDI. To derive model-independent constraints on dark energy, it is important to precisely measure the cosmic expansion history, H(z), in continuous redshift bins from z \\~ 0-2 (the redshift range in which dark energy is important). SNe Ia at z > 1 are not readily accessible from the ground because the bulk of their light has shifted into the near-infrared where the sky background is overwhelming; hence a space mission is required to probe dark energy using SNe. Because of its unique near-infrared wavelength coverage (0.8-4.2 microns), JEDI has the advantage of observing SNe Ia in the rest frame J band for the entire redshift range of 0 operations, spectra and light curves will be obtained for ~4,000 SNe Ia at z < 2. The resulting constraints on dark energy are discussed, with special emphasis on the improved precision afforded by the rest frame near-infrared data.

  7. Significantly super-Chandrasekhar limiting mass white dwarfs as progenitors for peculiar over-luminous type Ia supernovae

    E-Print Network [OSTI]

    Mukhopadhyay, Banibrata

    2015-01-01

    Since 2012, we have initiated developing systematically the simplistic to rigorous models to prove that highly super-Chandrasekhar, as well as highly sub-Chandrasekhar, limiting mass white dwarfs are possible to exist. We show that the mass of highly magnetized or modified Einstein's gravity induced white dwarfs could be significantly super-Chandrasekhar and such white dwarfs could altogether have a different mass-limit. On the other hand, type Ia supernovae (SNeIa), a key to unravel the evolutionary history of the universe, are believed to be triggered in white dwarfs having mass close to the Chandrasekhar-limit. However, observations of several peculiar, over- and under-luminous SNeIa argue for exploding masses widely different from this limit. We argue that explosions of super-Chandrasekhar limiting mass white dwarfs result in over-luminous SNeIa. We arrive at this revelation, first by considering simplistic, spherical, Newtonian white dwarfs with constant magnetic fields. Then we relax the Newtonian assum...

  8. Experto Universitario Java Enterprise Componentes de presentacin 2012-2013 Depto. Ciencia de la Computacin e IA Sesin 1

    E-Print Network [OSTI]

    Escolano, Francisco

    Experto Universitario Java Enterprise Componentes de presentación © 2012-2013 Depto. Ciencia de la Universitario Java Enterprise Componentes de presentación © 2012-2013 Depto. Ciencia de la Computación e IA Sesión 1 Experto Universitario Java Enterprise · Framewoks RIA basados en el servidor · Características

  9. Utilizing the Updated Gamma-Ray Bursts and Type Ia Supernovae to Constrain the Cardassian Expansion Model and Dark Energy

    E-Print Network [OSTI]

    Wei, Jun-Jie; Wu, Xue-Feng

    2015-01-01

    We update gamma-ray burst (GRB) luminosity relations among certain spectral and light-curve features with 139 GRBs. The distance modulus of 82 GRBs at $z>1.4$ can be calibrated with the sample at $z\\leq1.4$ by using the cubic spline interpolation method from the Union2.1 Type Ia supernovae (SNe Ia) set. We investigate the joint constraints on the Cardassian expansion model and dark energy with 580 Union2.1 SNe Ia sample ($z<1.4$) and 82 calibrated GRBs data ($1.4Ia significantly improves the constrain on $\\Omega_{m}-\\Omega_{\\Lambda}$ plane. In the Cardassian expansion model, the best fit is $\\Omega_{m}= 0.24_{-0.15}^{+0.15}$ and $n=0.16_{-0.52}^{+0.30}$ $(1\\sigma)$, which is consistent with the $\\Lambda$CDM cosmology $(n=0)$ in the $1\\sigma$ confidence region. We also discuss two dark energy models in which the equation of state $w(z)$ is parametrized as $w(z)=w_{0}$ and $w(z)=w_{0}+w_{1}z/(1+z)$, respectively. Based on o...

  10. On the Semiclassical Jacobi Algorithm \\Lambda Mar'ia T. C'amara and Domingo Gim'enez y

    E-Print Network [OSTI]

    Giménez, Domingo

    Chapter 1 On the Semiclassical Jacobi Algorithm \\Lambda Mar'ia T. C'amara and Domingo Gim'enez y Abstract In this paper a new Jacobi method to solve the symmetric eigenvalue problem is presented Jacobi methods. By combining this method with an adequate threshold strategy a reduction in the execution

  11. Late-Time Photometry of Type Ia Supernova SN2012cg Reveals the Radioactive Decay of $^{57}$Co

    E-Print Network [OSTI]

    Graur, Or; Shara, Michael M; Riess, Adam G

    2015-01-01

    Seitenzahl et al. (2009) have predicted that $\\sim 3$ years after its explosion, the light we receive from a Type Ia supernova will come mostly from reprocessing of electrons and X-rays emitted by the radioactive decay chain $^{57}{\\rm Co}~\\to~^{57}{\\rm Fe}$, instead of positrons from the decay chain $^{56}{\\rm Co}~\\to~^{56}{\\rm Fe}$ that dominates the supernova light at earlier times. Using the Hubble Space Telescope, we followed the light curve of the Type Ia supernova SN2012cg out to $1055$ days after maximum light. Our measurements are consistent with the light curves predicted by the contribution of energy from the reprocessing of electrons and X-rays emitted by the decay of $^{57}$Co. This provides conclusive evidence that $^{57}$Co is produced in Type Ia supernova explosions. The ratio of luminosities produced by the decays of $^{57}$Co and $^{56}$Co, a strong constraint on any Type Ia supernova explosion model, is in the range $(0.4$ - $8.5)\\times10^{-3}$.

  12. Improved device performance of InAs/GaAs quantum dot solar cells with GaP strain compensation layers

    E-Print Network [OSTI]

    Jalali. Bahram

    Improved device performance of InAs/GaAs quantum dot solar cells with GaP strain compensation Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico optical, electrical, and spectral response characteristics of three-stack InAs/GaAs quantum dot solar

  13. Lattice-Mismatched GaAs/InGaAs Two-Junction Solar Cells by Direct Wafer Bonding

    SciTech Connect (OSTI)

    Tanabe, K.; Aiken, D. J.; Wanlass, M. W.; Morral, A. F.; Atwater, H. A.

    2006-01-01

    Direct bonded interconnect between subcells of a lattice-mismatched III-V compound multijunction cell would enable dislocation-free active regions by confining the defect network needed for lattice mismatch accommodation to tunnel junction interfaces, while metamorphic growth inevitably results in less design flexibility and lower material quality than is desirable. The first direct-bond interconnected multijunction solar cell, a two-terminal monolithic GaAs/InGaAs two-junction solar cell, is reported and demonstrates viability of direct wafer bonding for solar cell applications. The tandem cell open-circuit voltage was approximately the sum of the subcell open-circuit voltages. This achievement shows direct bonding enables us to construct lattice-mismatched III-V multijunction solar cells and is extensible to an ultrahigh efficiency InGaP/GaAs/InGaAsP/InGaAs four-junction cell by bonding a GaAs-based lattice-matched InGaP/GaAs subcell and an InP-based lattice-matched InGaAsP/InGaAs subcell. The interfacial resistance experimentally obtained for bonded GaAs/InP smaller than 0.10 Ohm-cm{sup 2} would result in a negligible decrease in overall cell efficiency of {approx}0.02%, under 1-sun illumination.

  14. STANDARDIZING TYPE Ia SUPERNOVA ABSOLUTE MAGNITUDES USING GAUSSIAN PROCESS DATA REGRESSION

    SciTech Connect (OSTI)

    Kim, A. G.; Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Nordin, J. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States)] [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Thomas, R. C. [Computational Cosmology Center, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road MS 50B-4206, Berkeley, CA 94720 (United States)] [Computational Cosmology Center, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road MS 50B-4206, Berkeley, CA 94720 (United States); Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J. [Laboratoire de Physique Nucleaire et des Hautes Energies, Universite Pierre et Marie Curie Paris 6, Universite Denis Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, F-75252 Paris Cedex 05 (France)] [Laboratoire de Physique Nucleaire et des Hautes Energies, Universite Pierre et Marie Curie Paris 6, Universite Denis Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, F-75252 Paris Cedex 05 (France); Baltay, C. [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States)] [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States); Buton, C.; Kerschhaggl, M.; Kowalski, M. [Physikalisches Institut, Universitaet Bonn, Nussallee 12, D-53115 Bonn (Germany)] [Physikalisches Institut, Universitaet Bonn, Nussallee 12, D-53115 Bonn (Germany); Chotard, N. [Tsinghua Center for Astrophysics, Tsinghua University, Beijing 100084 (China)] [Tsinghua Center for Astrophysics, Tsinghua University, Beijing 100084 (China); Copin, Y.; Gangler, E. [Universite de Lyon, F-69622 Lyon (France)] [Universite de Lyon, F-69622 Lyon (France); and others

    2013-04-01

    We present a novel class of models for Type Ia supernova time-evolving spectral energy distributions (SEDs) and absolute magnitudes: they are each modeled as stochastic functions described by Gaussian processes. The values of the SED and absolute magnitudes are defined through well-defined regression prescriptions, so that data directly inform the models. As a proof of concept, we implement a model for synthetic photometry built from the spectrophotometric time series from the Nearby Supernova Factory. Absolute magnitudes at peak B brightness are calibrated to 0.13 mag in the g band and to as low as 0.09 mag in the z = 0.25 blueshifted i band, where the dispersion includes contributions from measurement uncertainties and peculiar velocities. The methodology can be applied to spectrophotometric time series of supernovae that span a range of redshifts to simultaneously standardize supernovae together with fitting cosmological parameters.

  15. Small-scale Interaction of Turbulence with Thermonuclear Flames in Type Ia Supernovae

    E-Print Network [OSTI]

    J. C. Niemeyer; W. K. Bushe; G. R. Ruetsch

    1999-05-07

    Microscopic turbulence-flame interactions of thermonuclear fusion flames occuring in Type Ia Supernovae were studied by means of incompressible direct numerical simulations with a highly simplified flame description. The flame is treated as a single diffusive scalar field with a nonlinear source term. It is characterized by its Prandtl number, Pr << 1, and laminar flame speed, S_L. We find that if S_L ~ u', where u' is the rms amplitude of turbulent velocity fluctuations, the local flame propagation speed does not significantly deviate from S_L even in the presence of velocity fluctuations on scales below the laminar flame thickness. This result is interpreted in the context of subgrid-scale modeling of supernova explosions and the mechanism for deflagration-detonation-transitions.

  16. Near-infrared line identification in type Ia supernovae during the transitional phase

    SciTech Connect (OSTI)

    Friesen, Brian; Baron, E.; Wisniewski, John P.; Miller, Timothy R. [Homer L. Dodge Department of Physics and Astronomy, 440 West Brooks Street, Room 100, Norman, OK 73019 (United States); Parrent, Jerod T. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Thomas, R. C. [Computational Cosmology Center, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road MS 50B-4206, Berkeley, CA 94720 (United States); Marion, G. H. [University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259 (United States)

    2014-09-10

    We present near-infrared synthetic spectra of a delayed-detonation hydrodynamical model and compare them to observed spectra of four normal Type Ia supernovae ranging from day +56.5 to day +85. This is the epoch during which supernovae are believed to be undergoing the transition from the photospheric phase, where spectra are characterized by line scattering above an optically thick photosphere, to the nebular phase, where spectra consist of optically thin emission from forbidden lines. We find that most spectral features in the near-infrared can be accounted for by permitted lines of Fe II and Co II. In addition, we find that [Ni II] fits the emission feature near 1.98 ?m, suggesting that a substantial mass of {sup 58}Ni exists near the center of the ejecta in these objects, arising from nuclear burning at high density.

  17. The $m$-$z$ relation for Type Ia supernovae: safety in numbers or safely without worry?

    E-Print Network [OSTI]

    Helbig, Phillip

    2015-01-01

    The $m$-$z$ relation for Type Ia supernovae is compatible with the cosmological concordance model if one assumes that the Universe is homogeneous, at least with respect to light propagation. This could be due to the density along each line of sight being equal to the overall cosmological density, or to `safety in numbers', with variation in the density along all lines of sight averaging out if the sample is large enough. Statistical correlations (or lack thereof) between redshifts, residuals (differences between the observed distance moduli and those calculated from the best-fitting cosmological model), and observational uncertainties suggest that the former scenario is the better description, so that one can use the traditional formula for the luminosity distance safely without worry.

  18. The Internal Shear of Type Ia Supernova Progenitors During Accretion and Simmering

    E-Print Network [OSTI]

    Piro, Anthony L

    2008-01-01

    A white dwarf (WD) gains substantial angular momentum during the accretion process that grows it toward a Chandrasekhar mass. It is therefore expected to be quickly rotating when it ignites as a Type Ia supernova. The thermal and shearing profile are important for subsequent flame propagation. We highlight processes that could affect the WD shear, during accretion as well as during the ~1000 years of pre-explosive simmering. Baroclinic instabilities and/or the shear growth of small magnetic fields provide sufficient torque to bring the WD very close to solid body rotation during accretion. The lack of significant shear makes it difficult to grow a WD substantially past the typical Chandrasekhar mass. Once carbon ignites, a convective region spreads from the WD's center. This phase occurs regardless of progenitor scenario, and therefore it is of great interest for understanding how the WD interior is prepared before the explosive burning begins. We summarize some of the key properties of the convective region,...

  19. Properties of (Ga,Mn)As codoped with Li

    SciTech Connect (OSTI)

    Miyakozawa, Shohei; Chen, Lin; Matsukura, Fumihiro; Ohno, Hideo

    2014-06-02

    We grow Li codoped (Ga,Mn)As layers with nominal Mn composition up to 0.15 by molecular beam epitaxy. The layers before and after annealing are characterized by x-ray diffraction, transport, magnetization, and ferromagnetic resonance measurements. The codoping with Li reduces the lattice constant and electrical resistivity of (Ga,Mn)As after annealing. We find that (Ga,Mn)As:Li takes similar Curie temperature to that of (Ga,Mn)As, but with pronounced magnetic moments and in-plane magnetic anisotropy, indicating that the Li codoping has nontrivial effects on the magnetic properties of (Ga,Mn)As.

  20. 56 IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 1, JANUARY 2012 Metamorphic GaAsP and InGaP Solar Cells on GaAs

    E-Print Network [OSTI]

    Haller, Gary L.

    solar cells are triple-junction concentrator devices, with each junction efficiently col- lecting subcell in a multijunction de- vice. GaAs0.66 P0.34 single-junction solar cells with Eg = 1.83 eV were56 IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 1, JANUARY 2012 Metamorphic GaAsP and InGaP Solar

  1. Incompatibility of a comoving Ly-alpha forest with supernova-Ia luminosity distances

    E-Print Network [OSTI]

    Jens Thomas; Hartmut Schulz

    2001-03-18

    Recently Perlmutter et al. suggested a positive value of Einstein's cosmological constant Lambda on the basis of luminosity distances from type-Ia supernovae. However, Lambda world models had earlier been proposed by Hoell & Priester and Liebscher et al. on the basis of quasar absorption-line data. Employing more general repulsive fluids ("dark energy") encompassing the Lambda component we quantitatively compare both approaches with each other. Fitting the SN-data by a minimum-component model consisting of dark energy + dust yields a closed universe with a large amount of dust exceeding the baryonic content constrained by big-bang nucleosynthesis. The nature of the dark energy is hardly constrained. Only when enforcing a flat universe there is a clear tendency to a dark-energy Lambda fluid and the `canonical' value Omega_M = 0.3 for dust. Conversely, fitting the quasar-data by a minimum-component model yields a sharply defined, slightly closed model with a low dust density ruling out significant pressureless dark matter. The dark-energy component obtains an equation-of-state P = -0.96 epsilon close to that of a Lambda-fluid. Omega_M = 0.3 or a precisely flat spatial geometry are inconsistent with minimum-component models. It is found that quasar and supernova data sets cannot be reconciled with each other via (repulsive ideal fluid+dust+radiation)-world models. Compatibility could be reached by drastic expansion of the parameter space with at least two exotic fluids added to dust and radiation as world constituents. If considering such solutions as far-fetched one has to conclude that the quasar absorption line and the SN-Ia constraints are incompatible.

  2. EARLY OBSERVATIONS AND ANALYSIS OF THE TYPE Ia SN 2014J IN M82

    SciTech Connect (OSTI)

    Marion, G. H.; Vinkó, J. [University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259 (United States); Sand, D. J. [Physics Department, Texas Tech University, Lubbock, TX 79409 (United States); Hsiao, E. Y. [Carnegie Observatories, Las Campanas Observatory, Colina El Pino, Casilla 601 (Chile); Banerjee, D. P. K.; Joshi, V.; Venkataraman, V.; Ashok, N. M. [Astronomy and Astrophysics Division, Physical Research Laboratory, Navrangapura, Ahmedabad - 380009, Gujarat (India); Valenti, S.; Howell, D. A. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States); Stritzinger, M. D. [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Amanullah, R.; Johansson, J. [The Oskar Klein Centre, Physics Department, Stockholm University, Albanova University Center, SE 106 91 Stockholm (Sweden); Binzel, R. P. [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Bochanski, J. J. [Haverford College, 370 Lancaster Avenue, Haverford, PA 19041 (United States); Bryngelson, G. L. [Department of Physics and Astronomy, Francis Marion University, 4822 East Palmetto Street, Florence, SC 29506 (United States); Burns, C. R. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Drozdov, D. [Department of Physics and Astronomy, Clemson University, 8304 University Station, Clemson, SC 29634 (United States); Fieber-Beyer, S. K. [Department of Space Studies, University of North Dakota, University Stop 9008, ND 58202 (United States); Graham, M. L., E-mail: hman@astro.as.utexas.edu [Astronomy Department, University of California at Berkeley, Berkeley, CA 94720 (United States); and others

    2015-01-01

    We present optical and near infrared (NIR) observations of the nearby Type Ia SN 2014J. Seventeen optical and 23 NIR spectra were obtained from 10 days before (–10d) to 10 days after (+10d) the time of maximum B-band brightness. The relative strengths of absorption features and their patterns of development can be compared at one day intervals throughout most of this period. Carbon is not detected in the optical spectra, but we identify C I ?1.0693 in the NIR spectra. Mg II lines with high oscillator strengths have higher initial velocities than other Mg II lines. We show that the velocity differences can be explained by differences in optical depths due to oscillator strengths. The spectra of SN 2014J show that it is a normal SN Ia, but many parameters are near the boundaries between normal and high-velocity subclasses. The velocities for O I, Mg II, Si II, S II, Ca II, and Fe II suggest that SN 2014J has a layered structure with little or no mixing. That result is consistent with the delayed detonation explosion models. We also report photometric observations, obtained from –10d to +29d, in the UBVRIJH and K{sub s} bands. The template fitting package SNooPy is used to interpret the light curves and to derive photometric parameters. Using R{sub V} = 1.46, which is consistent with previous studies, SNooPy finds that A{sub V} = 1.80 for E(B – V){sub host} = 1.23 ± 0.06 mag. The maximum B-band brightness of –19.19 ± 0.10 mag was reached on February 1.74 UT ± 0.13 days and the supernova has a decline parameter, ?m {sub 15}, of 1.12 ± 0.02 mag.

  3. Sensitivity study of explosive nucleosynthesis in Type Ia supernovae: I. Modification of individual thermonuclear reaction rates

    E-Print Network [OSTI]

    Eduardo Bravo; Gabriel Martínez-Pinedo

    2012-04-09

    We explore the sensitivity of the nucleosynthesis due to type Ia supernovae with respect to uncertainties in nuclear reaction rates. We have adopted a standard one-dimensional delayed detonation model of the explosion of a Chandrasekhar-mass white dwarf, and have post-processed the thermodynamic trajectories of every mass-shell with a nucleosynthetic code, with increases (decreases) by a factor of ten on the rates of 1196 nuclear reactions. We have computed as well hydrodynamic models for different rates of the fusion reactions of 12C and of 16O. For selected reactions, we have recomputed the nucleosynthesis with alternative prescriptions for their rates taken from the JINA REACLIB database, and have analyzed the temperature ranges where modifications of their rates have the strongest effect on nucleosynthesis. The nucleosynthesis resulting from the Type Ia supernova models is quite robust with respect to variations of nuclear reaction rates, with the exception of the reaction of fusion of 12C nuclei. The energy of the explosion changes by less than \\sim4%. The changes in the nucleosynthesis due to the modification of the rates of fusion reactions are as well quite modest, for instance no species with a mass fraction larger than 0.02 experiences a variation of its yield larger than a factor of two. We provide the sensitivity of the yields of the most abundant species with respect to the rates of the most intense reactions with protons, neutrons, and alphas. In general, the yields of Fe-group nuclei are more robust than the yields of intermediate-mass elements. Among the charged particle reactions, the most influential on supernova nucleosynthesis are 30Si + p \\rightleftarrows 31P + {\\gamma}, 20Ne + {\\alpha} \\rightleftarrows 24Mg + {\\gamma}, and 24Mg + {\\alpha} \\rightleftarrows 27Al + p. The temperatures at which a modification of their rate has a larger impact are in the range 2 < T < 4 GK. (abridged)

  4. EVOLUTION OF POST-IMPACT REMNANT HELIUM STARS IN TYPE Ia SUPERNOVA REMNANTS WITHIN THE SINGLE-DEGENERATE SCENARIO

    SciTech Connect (OSTI)

    Pan, Kuo-Chuan; Ricker, Paul M. [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Taam, Ronald E., E-mail: kpan2@illinois.edu, E-mail: pmricker@illinois.edu, E-mail: r-taam@northwestern.edu [Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States)

    2013-08-10

    The progenitor systems of Type Ia supernovae (SNe Ia) are still under debate. Based on recent hydrodynamics simulations, non-degenerate companions in the single-degenerate scenario (SDS) should survive the supernova (SN) impact. One way to distinguish between the SDS and the double-degenerate scenario is to search for the post-impact remnant stars (PIRSs) in SN Ia remnants. Using a technique that combines multi-dimensional hydrodynamics simulations with one-dimensional stellar evolution simulations, we have examined the post-impact evolution of helium-rich binary companions in the SDS. It is found that these helium-rich PIRSs (He PIRSs) dramatically expand and evolve to a luminous phase (L {approx} 10{sup 4} L{sub Sun }) about 10 yr after an SN explosion. Subsequently, they contract and evolve to become hot blue-subdwarf-like (sdO-like) stars by releasing gravitational energy, persisting as sdO-like stars for several million years before evolving to the helium red-giant phase. We therefore predict that a luminous OB-like star should be detectable within {approx}30 yr after the SN explosion. Thereafter, it will shrink and become an sdO-like star in the central regions of SN Ia remnants within star-forming regions for SN Ia progenitors evolved via the helium-star channel in the SDS. These He PIRSs are predicted to be rapidly rotating (v{sub rot} {approx}> 50 km s{sup -1}) and to have high spatial velocities (v{sub linear} {approx}> 500 km s{sup -1}). Furthermore, if SN remnants have diffused away and are not recognizable at a later stage, He PIRSs could be an additional source of single sdO stars and/or hypervelocity stars.

  5. MI C H I GA N M E M O R I A L P H O E N I X PROJECT

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousandReport) | SciTech ConnectFuture3,Last

  6. Reactive codoping of GaAlInP compound semiconductors

    DOE Patents [OSTI]

    Hanna, Mark Cooper (Boulder, CO); Reedy, Robert (Golden, CO)

    2008-02-12

    A GaAlInP compound semiconductor and a method of producing a GaAlInP compound semiconductor are provided. The apparatus and method comprises a GaAs crystal substrate in a metal organic vapor deposition reactor. Al, Ga, In vapors are prepared by thermally decomposing organometallic compounds. P vapors are prepared by thermally decomposing phospine gas, group II vapors are prepared by thermally decomposing an organometallic group IIA or IIB compound. Group VIB vapors are prepared by thermally decomposing a gaseous compound of group VIB. The Al, Ga, In, P, group II, and group VIB vapors grow a GaAlInP crystal doped with group IIA or IIB and group VIB elements on the substrate wherein the group IIA or IIB and a group VIB vapors produced a codoped GaAlInP compound semiconductor with a group IIA or IIB element serving as a p-type dopant having low group II atomic diffusion.

  7. Three-junction solar cells comprised of a thin-film GaInP/GaAs tandem cell mechanically stacked on a Si cell

    SciTech Connect (OSTI)

    Yazawa, Y.; Tamura, K.; Watahiki, S.; Kitatani, T.; Ohtsuka, H.; Warabisako, T.

    1997-12-31

    Three-junction tandem solar cells were fabricated by mechanical stacking of a thin-film GaInP/GaAs monolithic tandem cell and a Si cell. The epitaxial lift-off (ELO) technique was used for the thinning of GaInP/GaAs tandem cells. Both spectral responses of the GaInP top cell and the GaAs middle cell in the thin-film GaInP/GaAs monolithic tandem cell were conserved. The Si cell performance has been improved by reducing the absorption loss in the GaAs substrate.

  8. Chemical beam epitaxy growth of AlGaAs/GaAs tunnel junctions using trimethyl aluminium for multijunction solar cells

    SciTech Connect (OSTI)

    Paquette, B.; DeVita, M.; Turala, A.; Kolhatkar, G.; Boucherif, A.; Jaouad, A.; Aimez, V.; Arès, R.; Wilkins, M.; Wheeldon, J. F.; Walker, A. W.; Hinzer, K.; Fafard, S.

    2013-09-27

    AlGaAs/GaAs tunnel junctions for use in high concentration multijunction solar cells were designed and grown by chemical beam epitaxy (CBE) using trimethyl aluminium (TMA) as the p-dopant source for the AlGaAs active layer. Controlled hole concentration up to 4?10{sup 20} cm{sup ?3} was achieved through variation in growth parameters. Fabricated tunnel junctions have a peak tunneling current up to 6140 A/cm{sup 2}. These are suitable for high concentration use and outperform GaAs/GaAs tunnel junctions.

  9. 0.7-eV GaInAs Junction for a GaInP/GaAs/GaInAs(1eV)/GaInAs(0.7eV) Four-Junction Solar Cell

    SciTech Connect (OSTI)

    Friedman, D. J.; Geisz, J. F.; Norman, A. G.; Wanlass, M. W.; Kurtz, S. R.

    2006-01-01

    We discuss recent developments in III-V multijunction solar cells, focusing on adding a fourth junction to the Ga{sub 0.5}In{sub 0.5} P/GaAs/Ga{sub 0.75}In{sub 0.25}As inverted three-junction cell. This cell, grown inverted on GaAs so that the lattice-mismatched Ga{sub 0.75}In{sub 0.25}As third junction is the last one grown, has demonstrated 38% efficiency, and 40% is likely in the near future. To achieve still further gains, a lower-bandgap Ga{sub x}In{sub 1-x}As fourth junction could be added to the three-junction structure for a four-junction cell whose efficiency could exceed 45% under concentration. Here, we present the initial development of the Ga{sub x}In{sub 1-x}As fourth junction. Junctions of various bandgaps ranging from 0.88 to 0.73 eV were grown, in order to study the effect of the different amounts of lattice mismatch. At a bandgap of 0.88 eV, junctions were obtained with very encouraging {approx}80% quantum efficiency, 57% fill factor, and 0.36 eV open-circuit voltage. The device performance degrades with decreasing bandgap (i.e., increasing lattice mismatch). We model the four-junction device efficiency vs. fourth junction bandgap to show that an 0.7-eV fourth-junction bandgap, while optimal if it could be achieved in practice, is not necessary; an 0.9-eV bandgap would still permit significant gains in multijunction cell efficiency while being easier to achieve than the lower-bandgap junction.

  10. PIANO DI RIQUALIFICAZIONE AMBIENTALE E PAESAGGISTICA DEL TERMOVALORIZZATORE DI DESIO TERMOVALORIZZATORE DI DESIO (MI) BRIANZA ENERGIA E AMBIENTE SPA

    E-Print Network [OSTI]

    Columbia University

    TERMOVALORIZZATORE DI DESIO (MI) ­ BRIANZA ENERGIA E AMBIENTE SPA Impianto di costruito negli anni '70 per lo. · Energia elettrica prodotta: 13.000.000 KWh/anno. LAND S.r.l. Landscape Architecture Nature Development

  11. Electron tunneling spectroscopy study of electrically active traps in AlGaN/GaN high electron mobility transistors

    SciTech Connect (OSTI)

    Yang, Jie Cui, Sharon; Ma, T. P.; Hung, Ting-Hsiang; Nath, Digbijoy; Krishnamoorthy, Sriram; Rajan, Siddharth

    2013-11-25

    We investigate the energy levels of electron traps in AlGaN/GaN high electron mobility transistors by the use of electron tunneling spectroscopy. Detailed analysis of a typical spectrum, obtained in a wide gate bias range and with both bias polarities, suggests the existence of electron traps both in the bulk of AlGaN and at the AlGaN/GaN interface. The energy levels of the electron traps have been determined to lie within a 0.5?eV band below the conduction band minimum of AlGaN, and there is strong evidence suggesting that these traps contribute to Frenkel-Poole conduction through the AlGaN barrier.

  12. A InGaN/GaN quantum dot green ({lambda}=524 nm) laser

    SciTech Connect (OSTI)

    Zhang Meng; Banerjee, Animesh; Lee, Chi-Sen; Hinckley, John M.; Bhattacharya, Pallab

    2011-05-30

    The characteristics of self-organized InGaN/GaN quantum dot lasers are reported. The laser heterostructures were grown on c-plane GaN substrates by plasma-assisted molecular beam epitaxy and the laser facets were formed by focused ion beam etching with gallium. Emission above threshold is characterized by a peak at 524 nm (green) and linewidth of 0.7 nm. The lowest measured threshold current density is 1.2 kA/cm{sup 2} at 278 K. The slope and wall plug efficiencies are 0.74 W/A and {approx}1.1%, respectively, at 1.3 kA/cm{sup 2}. The value of T{sub 0}=233 K in the temperature range of 260-300 K.

  13. Photocapacitance study of type-II GaSb/GaAs quantum ring solar cells

    SciTech Connect (OSTI)

    Wagener, M. C.; Botha, J. R.; Carrington, P. J.; Krier, A.

    2014-01-07

    In this study, the density of states associated with the localization of holes in GaSb/GaAs quantum rings are determined by the energy selective charging of the quantum ring distribution. The authors show, using conventional photocapacitance measurements, that the excess charge accumulated within the type-II nanostructures increases with increasing excitation energies for photon energies above 0.9?eV. Optical excitation between the localized hole states and the conduction band is therefore not limited to the ?(k?=?0) point, with pseudo-monochromatic light charging all states lying within the photon energy selected. The energy distribution of the quantum ring states could consequently be accurately related from the excitation dependence of the integrated photocapacitance. The resulting band of localized hole states is shown to be well described by a narrow distribution centered 407?meV above the GaAs valence band maximum.

  14. Efficiency enhancement of InGaN/GaN solar cells with nanostructures

    SciTech Connect (OSTI)

    Bai, J.; Yang, C. C.; Athanasiou, M.; Wang, T.

    2014-02-03

    We demonstrate InGaN/GaN multi-quantum-well solar cells with nanostructures operating at a wavelength of 520?nm. Nanostructures with a periodic nanorod or nanohole array are fabricated by means of modified nanosphere lithography. Under 1 sun air-mass 1.5 global spectrum illumination, a fill factor of 50 and an open circuit voltage of 1.9?V are achieved in spite of very high indium content in InGaN alloys usually causing degradation of crystal quality. Both the nanorod array and the nanohole array significantly improve the performance of solar cells, while a larger enhancement is observed for the nanohole array, where the conversion efficiency is enhanced by 51%.

  15. Graphene in ohmic contact for both n-GaN and p-GaN

    SciTech Connect (OSTI)

    Zhong, Haijian; Liu, Zhenghui; Shi, Lin; Xu, Gengzhao; Fan, Yingmin; Huang, Zengli [Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Wang, Jianfeng; Ren, Guoqiang; Xu, Ke, E-mail: kxu2006@sinano.ac.cn [Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Suzhou Nanowin Science and Technology Co., Ltd., Suzhou 215123 (China)

    2014-05-26

    The wrinkles of single layer graphene contacted with either n-GaN or p-GaN were found both forming ohmic contacts investigated by conductive atomic force microscopy. The local I–V results show that some of the graphene wrinkles act as high-conductive channels and exhibiting ohmic behaviors compared with the flat regions with Schottky characteristics. We have studied the effects of the graphene wrinkles using density-functional-theory calculations. It is found that the standing and folded wrinkles with zigzag or armchair directions have a tendency to decrease or increase the local work function, respectively, pushing the local Fermi level towards n- or p-type GaN and thus improving the transport properties. These results can benefit recent topical researches and applications for graphene as electrode material integrated in various semiconductor devices.

  16. Measurement of Pi-K Ratios from the NuMI Target

    SciTech Connect (OSTI)

    Seun, Sin Man; /Harvard U.

    2007-07-01

    Interactions of protons (p) with the NuMI (Neutrinos at the Main Injector) target are used to create the neutrino beam for the MINOS (Main Injector Neutrino Oscillation Search) Experiment. Using the MIPP (Main Injector Particle Production) experimental apparatus, the production of charged pions and kaons in p+NuMI interactions is studied. The data come from a sample of 2 x 10{sup 6} events obtained by MIPP using the 120 GeV/c proton beam from the Main Injector at Fermi National Accelerator Laboratory in Illinois, USA. Pions and kaons are identified by measurement in a Ring Imaging Cherenkov detector. Presented are measurements of {pi}{sup -}/{pi}{sup +}, K{sup -}/K{sup +}, {pi}{sup +}/K{sup +} and {pi}{sup -}/K{sup -} production ratios in the momentum range p{sub T} < 2 GeV/c transversely and 20 GeV/c < p{sub z} < 90 GeV/c longitudinally. Also provided are detailed comparisons of the MIPP NuMI data with the MIPP Thin Carbon data, the MIPP Monte Carlo simulation and the current MINOS models in the relevant momentum ranges.

  17. Targeting miR-21 enhances the sensitivity of human colon cancer HT-29 cells to chemoradiotherapy in vitro

    SciTech Connect (OSTI)

    Deng, Jun; Lei, Wan; Fu, Jian-Chun; Zhang, Ling; Li, Jun-He; Xiong, Jian-Ping

    2014-01-17

    Highlight: •MiR-21 plays a significant role in 5-FU resistance. •This role might be attributed to targeting of hMSH2 as well as TP and DPD via miR-21 targeted hMSH2. •Indirectly targeted TP and DPD to influence 5-FU chemotherapy sensitivity. -- Abstract: 5-Fluorouracil (5-FU) is a classic chemotherapeutic drug that has been widely used for colorectal cancer treatment, but colorectal cancer cells are often resistant to primary or acquired 5-FU therapy. Several studies have shown that miR-21 is significantly elevated in colorectal cancer. This suggests that this miRNA might play a role in this resistance. In this study, we investigated this possibility and the possible mechanism underlying this role. We showed that forced expression of miR-21 significantly inhibited apoptosis, enhanced cell proliferation, invasion, and colony formation ability, promoted G1/S cell cycle transition and increased the resistance of tumor cells to 5-FU and X radiation in HT-29 colon cancer cells. Furthermore, knockdown of miR-21 reversed these effects on HT-29 cells and increased the sensitivity of HT-29/5-FU to 5-FU chemotherapy. Finally, we showed that miR-21 targeted the human mutS homolog2 (hMSH2), and indirectly regulated the expression of thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD). These results demonstrate that miR-21 may play an important role in the 5-FU resistance of colon cancer cells.

  18. Temperature dependency of the emission properties from positioned In(Ga)As/GaAs quantum dots

    SciTech Connect (OSTI)

    Braun, T.; Schneider, C.; Maier, S.; Forchel, A.; Höfling, S.; Kamp, M.; Igusa, R.; Iwamoto, S.; Arakawa, Y.

    2014-09-15

    In this letter we study the influence of temperature and excitation power on the emission linewidth from site-controlled InGaAs/GaAs quantum dots grown on nanoholes defined by electron beam lithography and wet chemical etching. We identify thermal electron activation as well as direct exciton loss as the dominant intensity quenching channels. Additionally, we carefully analyze the effects of optical and acoustic phonons as well as close-by defects on the emission linewidth by means of temperature and power dependent micro-photoluminescence on single quantum dots with large pitches.

  19. Origins of ion irradiation-induced Ga nanoparticle motion on GaAs surfaces

    SciTech Connect (OSTI)

    Kang, M.; Wu, J. H.; Chen, H. Y.; Thornton, K.; Goldman, R. S. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Sofferman, D. L. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, Adelphi University, Garden City, New York 11530-0701 (United States); Beskin, I. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)] [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)

    2013-08-12

    We have examined the origins of ion irradiation-induced nanoparticle (NP) motion. Focused-ion-beam irradiation of GaAs surfaces induces random walks of Ga NPs, which are biased in the direction opposite to that of ion beam scanning. Although the instantaneous NP velocities are constant, the NP drift velocities are dependent on the off-normal irradiation angle, likely due to a difference in surface non-stoichiometry induced by the irradiation angle dependence of the sputtering yield. It is hypothesized that the random walks are initiated by ion irradiation-induced thermal fluctuations, with biasing driven by anisotropic mass transport.

  20. GaN based nanorods for solid state lighting

    SciTech Connect (OSTI)

    Li Shunfeng; Waag, Andreas [Institute of Semiconductor Technology, Braunschweig University of Technology, 38106 Braunschweig (Germany)

    2012-04-01

    In recent years, GaN nanorods are emerging as a very promising novel route toward devices for nano-optoelectronics and nano-photonics. In particular, core-shell light emitting devices are thought to be a breakthrough development in solid state lighting, nanorod based LEDs have many potential advantages as compared to their 2 D thin film counterparts. In this paper, we review the recent developments of GaN nanorod growth, characterization, and related device applications based on GaN nanorods. The initial work on GaN nanorod growth focused on catalyst-assisted and catalyst-free statistical growth. The growth condition and growth mechanisms were extensively investigated and discussed. Doping of GaN nanorods, especially p-doping, was found to significantly influence the morphology of GaN nanorods. The large surface of 3 D GaN nanorods induces new optical and electrical properties, which normally can be neglected in layered structures. Recently, more controlled selective area growth of GaN nanorods was realized using patterned substrates both by metalorganic chemical vapor deposition (MOCVD) and by molecular beam epitaxy (MBE). Advanced structures, for example, photonic crystals and DBRs are meanwhile integrated in GaN nanorod structures. Based on the work of growth and characterization of GaN nanorods, GaN nanoLEDs were reported by several groups with different growth and processing methods. Core/shell nanoLED structures were also demonstrated, which could be potentially useful for future high efficient LED structures. In this paper, we will discuss recent developments in GaN nanorod technology, focusing on the potential advantages, but also discussing problems and open questions, which may impose obstacles during the future development of a GaN nanorod based LED technology.

  1. GaInP/GaAs dual junction solar cells on Ge/Si epitaxial templates Melissa J. Archer,1,a

    E-Print Network [OSTI]

    Atwater, Harry

    GaInP/GaAs dual junction solar cells on Ge/Si epitaxial templates Melissa J. Archer,1,a Daniel C, crack-free GaInP/GaAs double junction solar cells were grown by metal organic chemical vapor deposition with the world record efficiency is a metamorphic triple junction GaInP/GaAs/Ge cell.6 Alternatively, wafer

  2. Enhanced hole transport in InGaN/GaN multiple quantum well light-emitting

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    -emitting diodes (LEDs) are considered the new generation lighting sources due to their advantages in power Society of America OCIS codes: 230.3670, 230.5590, 160.6000. Nitride-based high-power light devoted to the development of high-brightness GaN-based LEDs [3­5]. Lateral hole spreading is one

  3. High-Efficiency GaInP/GaAs Tandem Solar Cells

    SciTech Connect (OSTI)

    Bertness, K. A.; Friedman, D. J.; Kurtz, S. R.; Kibbler, A. E.; Cramer, C.; Olson, J. M.

    1996-09-01

    GaInP/GaAs tandem solar cells have achieved efficiencies between 25.7-30.2%, depending on illumination conditions. The efficiencies are the highest confirmed two-terminal values measured for any solar cell within each standard illumination category. The monolithic, series-connected design of the tandem cells allows them to be substituted for silicon or gallium arsenide cells in photovoltaic panel systems with minimal design changes. The advantages of using GaInP/GaAs tandem solar cells in space and terrestrial applications are discussed primarily in terms of the reduction in balance-of-system costs that accrues when using a higher efficiency cell. The new efficiency values represent a significant improvement over previous efficiencies for this materials system, and we identify grid design, back interface passivation, and top interface passivation as the three key factors leading to this improvement. In producing the high-efficiency cells, we have addressed nondestructive diagnostics and materials growth reproducibility as well as peak cell performance.

  4. High-efficiency GaInP/GaAs tandem solar cells

    SciTech Connect (OSTI)

    Bertness, K.A.; Friedman, D.J.; Kurtz, S.R.; Kibbler, A.E.; Kramer, C.; Olson, J.M.

    1994-12-01

    GaInP/GaAs tandem solar cells have achieved new record efficiencies, specifically 25.7% under air-mass 0 (AM0) illumination, 29.5% under AM 1.5 global (AM1.5G) illumination, and 30.2% at 140-180x concentration under AM 1.5 direct (AM1.5D) illumination. These values are the highest two-terminal efficiencies achieved by any solar cell under these illumination conditions. The monolithic, series-connected design of the tandem cells allows them to be substituted for silicon or gallium arsenide cells in photovoltaic panel systems with minimal design changes. The advantages of using GaInP/GaAs tandem solar cells in space and terrestrial applications are discussed primarily in terms of the reduction in balance-of-system costs that accrues when using a higher efficiency cell. The new efficiency values represent a significant improvement over previous efficiencies for this materials system, and we identify grid design, back interface passivation, and top interface passivation as the three key factors leading to this improvement. In producing the high-efficiency cells, we have addressed nondestructive diagnostics and materials growth reproducibility as well as peak cell performance. 31 refs.

  5. TJ Solar Cell (GaInP/GaAs/Ge Ultrahigh-Efficiency Solar Cells

    SciTech Connect (OSTI)

    Friedman, Daniel

    2002-04-17

    This talk will discuss recent developments in III-V multijunction photovoltaic technology which have led to the highest-efficiency solar cells ever demonstrated. The relationship between the materials science of III-V semiconductors and the achievement of record solar cell efficiencies will be emphasized. For instance, epitaxially-grown GAInP has been found to form a spontaneously-ordered GaP/InP (111) superlattice. This ordering affects the band gap of the material, which in turn affects the design of solar cells which incorporate GaInP. For the next generation of ultrahigh-efficiency III-V solar cells, we need a new semiconductor which is lattice-matched to GaAs, has a band gap of 1 eV, and has long minority-carrier diffusion lengths. Out of a number of candidate materials, the recently-discovered alloy GaInNAs appears to have the greatest promise. This material satisfies the first two criteria, but has to date shown very low diffusion lengths, a problem which is our current focus in the development of these next-generation cells.

  6. Multijunction GaInP/GaInAs/Ge solar cells with Bragg reflectors

    SciTech Connect (OSTI)

    Emelyanov, V. M. Kalyuzhniy, N. A.; Mintairov, S. A.; Shvarts, M. Z.; Lantratov, V. M.

    2010-12-15

    Effect of subcell parameters on the efficiency of GaInP/Ga(In)As/Ge tandem solar cells irradiated with 1-MeV electrons at fluences of up to 3 x 10{sup 15} cm{sup -2} has been theoretically studied. The optimal thicknesses of GaInP and GaInAs subcells, which provide the best photocurrent matching at various irradiation doses in solar cells with and without built-in Bragg reflectors, were determined. The dependences of the photoconverter efficiency on the fluence of 1-MeV electrons and on the time of residence in the geostationary orbit were calculated for structures optimized to the beginning and end of their service lives. It is shown that the optimization of the subcell heterostructures for a rated irradiation dose and the introduction of Bragg reflectors into the structure provide a 5% overall increase in efficiency for solar cells operating in the orbit compared with unoptimized cells having no Bragg reflector.

  7. Localized corrosion of GaAs surfaces and formation of porous GaAs

    SciTech Connect (OSTI)

    Schmuki, P.; Vitus, C.M.; Isaacs, H.S.; Fraser, J.; Graham, M.J.

    1995-12-01

    The present work deals with pitting corrosion of p- and n-type GaAs (100). Pit growth can be electrochemically initiated on both conduction types in chloride-containing solutions and leads after extended periods of time to the formation of a porous GaAs structure. In the case of p-type material, localized corrosion is only observed if a passivating film is present on the surface, otherwise -- e.g. in acidic solutions -- the material suffers from a uniform attack (electropolishing) which is independent of the anion present. In contrast, pitting corrosion of n-type material can be triggered independent of the presence of an oxide film. This is explained in terms of the different current limiting factor for the differently doped materials (oxide film in the case of the p- and a space charge layer in the case of the n-GaAs). The porous structure was characterized by SEM, EDX and AES, and consists mainly of GaAs. From scratch experiments it is clear that the pit initiation process is strongly influenced by surface defects. For n-type material, AFM investigations show that light induced roughening of the order of several hundred nm occurs under non-passivating conditions. This nm- scale roughening however does not affect the pitting process.

  8. MiR-34a targets GAS1 to promote cell proliferation and inhibit apoptosis in papillary thyroid carcinoma via PI3K/Akt/Bad pathway

    SciTech Connect (OSTI)

    Ma, Yanfei; Qin, Huadong [Department of Fourth Surgery, the Second Affiliated Hospital of Harbin Medical University, 148 Xuefu Road, Nangang District, Harbin 150086 (China)] [Department of Fourth Surgery, the Second Affiliated Hospital of Harbin Medical University, 148 Xuefu Road, Nangang District, Harbin 150086 (China); Cui, Yunfu, E-mail: yfma77@126.com [Department of First Surgery, the Second Affiliated Hospital of Harbin Medical University, 148 Xuefu Road, Nangang District, Harbin 150086 (China)] [Department of First Surgery, the Second Affiliated Hospital of Harbin Medical University, 148 Xuefu Road, Nangang District, Harbin 150086 (China)

    2013-11-29

    Highlights: •MiR-34a is up- and GAS1 is down-regulated in papillary thyroid carcinoma. •GAS1 is a direct target for miR-34a. •MiR-34a promotes PTC cells proliferation and inhibits apoptosis through PI3K/Akt/Bad pathway. -- Abstract: MicroRNAs (miRNAs) are fundamental regulators of cell proliferation, differentiation, and apoptosis, and are implicated in tumorigenesis of many cancers. MiR-34a is best known as a tumor suppressor through repression of growth factors and oncogenes. Growth arrest specific1 (GAS1) protein is a tumor suppressor that inhibits cancer cell proliferation and induces apoptosis through inhibition of RET receptor tyrosine kinase. Both miR-34a and GAS1 are frequently down-regulated in various tumors. However, it has been reported that while GAS1 is down-regulated in papillary thyroid carcinoma (PTC), miR-34a is up-regulated in this specific type of cancer, although their potential roles in PTC tumorigenesis have not been examined to date. A computational search revealed that miR-34a putatively binds to the 3?-UTR of GAS1 gene. In the present study, we confirmed previous findings that miR-34a is up-regulated and GAS1 down-regulated in PTC tissues. Further studies indicated that GAS1 is directly targeted by miR-34a. Overexpression of miR-34a promoted PTC cell proliferation and colony formation and inhibited apoptosis, whereas knockdown of miR-34a showed the opposite effects. Silencing of GAS1 had similar growth-promoting effects as overexpression of miR-34a. Furthermore, miR-34a overexpression led to activation of PI3K/Akt/Bad signaling pathway in PTC cells, and depletion of Akt reversed the pro-growth, anti-apoptotic effects of miR-34a. Taken together, our results demonstrate that miR-34a regulates GAS1 expression to promote proliferation and suppress apoptosis in PTC cells via PI3K/Akt/Bad pathway. MiR-34a functions as an oncogene in PTC.

  9. MiR-145 is downregulated in human ovarian cancer and modulates cell growth and invasion by targeting p70S6K1 and MUC1

    SciTech Connect (OSTI)

    Wu, Huijuan; Xiao, ZhengHua; Wang, Ke; Liu, Wenxin; Hao, Quan

    2013-11-29

    Highlights: •MiR-145 is downregulated in human ovarian cancer. •MiR-145 targets p70S6K1 and MUC1. •p70S6K1 and MUC1 are involved in miR-145 mediated tumor cell growth and cell invasion, respectively. -- Abstract: MicroRNAs (miRNAs) are a family of small non-coding RNA molecules that regulate gene expression at post-transcriptional levels. Previous studies have shown that miR-145 is downregulated in human ovarian cancer; however, the roles of miR-145 in ovarian cancer growth and invasion have not been fully demonstrated. In the present study, Northern blot and qRT-PCR analysis indicate that miR-145 is downregulated in ovarian cancer tissues and cell lines, as well as in serum samples of ovarian cancer, compared to healthy ovarian tissues, cell lines and serum samples. Functional studies suggest that miR-145 overexpression leads to the inhibition of colony formation, cell proliferation, cell growth viability and invasion, and the induction of cell apoptosis. In accordance with the effect of miR-145 on cell growth, miR-145 suppresses tumor growth in vivo. MiR-145 is found to negatively regulate P70S6K1 and MUC1 protein levels by directly targeting their 3?UTRs. Importantly, the overexpression of p70S6K1 and MUC1 can restore the cell colony formation and invasion abilities that are reduced by miR-145, respectively. MiR-145 expression is increased after 5-aza-CdR treatment, and 5-aza-CdR treatment results in the same phenotype as the effect of miR-145 overexpression. Our study suggests that miR-145 modulates ovarian cancer growth and invasion by suppressing p70S6K1 and MUC1, functioning as a tumor suppressor. Moreover, our data imply that miR-145 has potential as a miRNA-based therapeutic target for ovarian cancer.

  10. Demonstration of a semipolar (10(1)over-bar(3)over-bar) InGaN/GaN green light emitting diode

    E-Print Network [OSTI]

    2005-01-01

    InGaN / GaN green light emitting diode R. Sharma, a? P. M.green ??525 nm? light emitting diode ?LED?. The fabricated

  11. Introducci'on a la Programaci'on L'ogica Posgrado en Ciencia e Ingenier'ia de la Computaci'on

    E-Print Network [OSTI]

    Velarde, Carlos

    Introducci'on a la Programaci'on L'ogica Posgrado en Ciencia e Ingenier'ia de la Computaci'on 1999­2 David Rosenblueth y Carlos Velarde Parte I: Conceptos B'asicos de la Programaci'on L'ogica 1 Hechos y resoluci'on 6 Resoluci'on en forma textual 7 Metodolog'ia de programaci'on 8 Listas, 1a parte 9 Prolog puro

  12. THE IMPACT OF TYPE Ia SUPERNOVA EXPLOSIONS ON HELIUM COMPANIONS IN THE CHANDRASEKHAR-MASS EXPLOSION SCENARIO

    SciTech Connect (OSTI)

    Liu Zhengwei; Wang, B.; Han, Z. W. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Pakmor, R. [Heidelberger Institut fuer Theoretische Studien, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Seitenzahl, I. R.; Hillebrandt, W.; Kromer, M.; Edelmann, P.; Taubenberger, S. [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany); Roepke, F. K. [Institut fuer Theoretische Physik und Astrophysik, Universitaet Wuerzburg, Am Hubland, D-97074 Wuerzburg (Germany); Maeda, K., E-mail: zwliu@ynao.ac.cn [Kavli Institute for the Physics and Mathematics of the Universe (Kavli-IPMU), Todai Institutes for Advanced Study (TODIAS), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)

    2013-09-01

    In the version of the single-degenerate scenario of Type Ia supernovae (SNe Ia) studied here, a carbon-oxygen white dwarf explodes close to the Chandrasekhar limit after accreting material from a non-degenerate helium (He) companion star. In the present study, we employ the STELLAR GADGET code to perform three-dimensional hydrodynamical simulations of the interaction of the SN Ia ejecta with the He companion star taking into account its orbital motion and spin. It is found that only 2%-5% of the initial companion mass is stripped off from the outer layers of He companion stars due to the supernova (SN) impact. The dependence of the unbound mass (or the kick velocity) on the orbital separation can be fitted to a good approximation by a power law for a given companion model. After the SN impact, the outer layers of a He donor star are significantly enriched with heavy elements from the low-expansion-velocity tail of SN Ia ejecta. The total mass of accumulated SN-ejecta material on the companion surface reaches about {approx}> 10{sup -3} M{sub Sun} for different companion models. This enrichment with heavy elements provides a potential way to observationally identify the surviving companion star in SN remnants. Finally, by artificially adjusting the explosion energy of the W7 explosion model, we find that the total accumulation of SN ejecta on the companion surface is also dependent on the explosion energy with a power-law relation to a good approximation.

  13. PRODUCTION OF THE p-PROCESS NUCLEI IN THE CARBON-DEFLAGRATION MODEL FOR TYPE Ia SUPERNOVAE

    SciTech Connect (OSTI)

    Kusakabe, Motohiko; Iwamoto, Nobuyuki; Nomoto, Ken'ichi E-mail: iwamoto.nobuyuki@jaea.go.jp

    2011-01-01

    We calculate the nucleosynthesis of proton-rich isotopes in the carbon-deflagration model for Type Ia supernovae (SNe Ia). The seed abundances are obtained by calculating the s-process nucleosynthesis that is expected to occur in the repeating helium shell flashes on the carbon-oxygen (CO) white dwarf (WD) during mass accretion from a binary companion. When the deflagration wave passes through the outer layer of the CO WD, p-nuclei are produced by photodisintegration reactions on s-nuclei in a region where the peak temperature ranges from 1.9 to 3.6 x 10{sup 9} K. We confirm the sensitivity of the p-process on the initial distribution of s-nuclei. We show that the initial C/O ratio in the WD does not affect much the yield of p-nuclei. On the other hand, the abundance of {sup 22}Ne left after s-processing has a large influence on the p-process via the {sup 22}Ne({alpha},n) reaction. We find that about 50% of p-nuclides are co-produced when normalized to their solar abundances in all adopted cases of seed distribution. Mo and Ru, which are largely underproduced in Type II supernovae (SNe II), are produced more than in SNe II although they are underproduced with respect to the yield levels of other p-nuclides. The ratios between p-nuclei and iron in the ejecta are larger than the solar ratios by a factor of 1.2. We also compare the yields of oxygen, iron, and p-nuclides in SNe Ia and SNe II and suggest that SNe Ia could make a larger contribution than SNe II to the solar system content of p-nuclei.

  14. Inverse spin Hall effect in Pt/(Ga,Mn)As

    SciTech Connect (OSTI)

    Nakayama, H.; Chen, L.; Chang, H. W.; Ohno, H.; Matsukura, F.

    2015-06-01

    We investigate dc voltages under ferromagnetic resonance in a Pt/(Ga,Mn)As bilayer structure. A part of the observed dc voltage is shown to originate from the inverse spin Hall effect. The sign of the inverse spin Hall voltage is the same as that in Py/Pt bilayer structure, even though the stacking order of ferromagnetic and nonmagnetic layers is opposite to each other. The spin mixing conductance at the Pt/(Ga,Mn)As interface is determined to be of the order of 10{sup 19?}m{sup ?2}, which is about ten times greater than that of (Ga,Mn)As/p-GaAs.

  15. Deep level defects in n-type GaAsBi and GaAs grown at low temperatures

    SciTech Connect (OSTI)

    Mooney, P. M.; Watkins, K. P.; Jiang, Zenan; Basile, A. F.; Lewis, R. B.; Bahrami-Yekta, V.; Masnadi-Shirazi, M.; Beaton, D. A.; Tiedje, T.

    2013-04-07

    Deep level defects in n-type GaAs{sub 1-x}Bi{sub x} having 0 < x < 0.012 and GaAs grown by molecular beam epitaxy (MBE) at substrate temperatures between 300 and 400 Degree-Sign C have been investigated by Deep Level Capacitance Spectroscopy. Incorporating Bi suppresses the formation of an electron trap with activation energy 0.40 eV, thus reducing the total trap concentration in dilute GaAsBi layers by more than a factor of 20 compared to GaAs grown under the same conditions. We find that the dominant traps in dilute GaAsBi layers are defect complexes involving As{sub Ga}, as expected for MBE growth at these temperatures.

  16. High efficiency InGaN/GaN light emitting diodes with asymmetric triangular multiple quantum wells

    SciTech Connect (OSTI)

    Chang, Chiao-Yun; Li, Hen; Lu, Tien-Chang, E-mail: timtclu@mail.nctu.edu.tw [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, 1001 University Road, Hsinchu, Taiwan 300 (China)

    2014-03-03

    In this study, we demonstrated high efficiency InGaN/GaN light emitting diodes (LEDs) with asymmetric triangular multiple quantum wells (MQWs). Asymmetric triangular MQWs not only contribute to uniform carrier distribution in InGaN/GaN MQWs but also yield a low Auger recombination rate. In addition, asymmetric triangular MQWs with gallium face-oriented inclination band profiles can be immune from the polarization charge originating from typical c-plane InGaN/GaN quantum well structures. In the experiment, LEDs incorporated with asymmetric triangular MQWs with gallium face-oriented inclination band profiles exhibited a 60.0% external quantum efficiency at 20?mA and a 27.0% efficiency droop at 100?mA (corresponding to a current density of 69?A/cm{sup 2}), which accounted for an 11.7% efficiency improvement and a 31.1% droop reduction compared with symmetric square quantum well structure LEDs.

  17. Deep level centers and their role in photoconductivity transients of InGaAs/GaAs quantum dot chains

    SciTech Connect (OSTI)

    Kondratenko, S. V. Vakulenko, O. V.; Mazur, Yu. I. Dorogan, V. G.; Marega, E.; Benamara, M.; Ware, M. E.; Salamo, G. J.

    2014-11-21

    The in-plane photoconductivity and photoluminescence are investigated in quantum dot-chain InGaAs/GaAs heterostructures. Different photoconductivity transients resulting from spectrally selecting photoexcitation of InGaAs QDs, GaAs spacers, or EL2 centers were observed. Persistent photoconductivity was observed at 80?K after excitation of electron-hole pairs due to interband transitions in both the InGaAs QDs and the GaAs matrix. Giant optically induced quenching of in-plane conductivity driven by recharging of EL2 centers is observed in the spectral range from 0.83?eV to 1.0?eV. Conductivity loss under photoexcitation is discussed in terms of carrier localization by analogy with carrier distribution in disordered media.

  18. Au impact on GaAs epitaxial growth on GaAs (111){sub B} substrates in molecular beam epitaxy

    SciTech Connect (OSTI)

    Liao, Zhi-Ming; Chen, Zhi-Gang; Xu, Hong-Yi; Guo, Ya-Nan; Sun, Wen; Zhang, Zhi; Yang, Lei; Lu, Zhen-Yu; Chen, Ping-Ping; Lu, Wei; Zou, Jin; Centre for Microscopy and Microanalysis, The University of Queensland, St. Lucia, Queensland 4072

    2013-02-11

    GaAs growth behaviour under the presence of Au nanoparticles on GaAs {l_brace}111{r_brace}{sub B} substrate is investigated using electron microscopy. It has been found that, during annealing, enhanced Ga surface diffusion towards Au nanoparticles leads to the GaAs epitaxial growth into {l_brace}113{r_brace}{sub B} faceted triangular pyramids under Au nanoparticles, governed by the thermodynamic growth, while during conventional GaAs growth, growth kinetics dominates, resulting in the flatted triangular pyramids at high temperature and the epitaxial nanowires growth at relatively low temperature. This study provides an insight of Au nanoparticle impact on GaAs growth, which is critical for understanding the formation mechanisms of semiconductor nanowires.

  19. Spectroscopic Properties of Star-Forming Host Galaxies and Type Ia Supernova Hubble Residuals in a Nearly Unbiased Sample

    SciTech Connect (OSTI)

    D'Andrea, Chris B.; et al.

    2011-12-20

    We examine the correlation between supernova host galaxy properties and their residuals on the Hubble diagram. We use supernovae discovered during the Sloan Digital Sky Survey II - Supernova Survey, and focus on objects at a redshift of z < 0.15, where the selection effects of the survey are known to yield a complete Type Ia supernova sample. To minimize the bias in our analysis with respect to measured host-galaxy properties, spectra were obtained for nearly all hosts, spanning a range in magnitude of -23 < M_r < -17. In contrast to previous works that use photometric estimates of host mass as a proxy for global metallicity, we analyze host-galaxy spectra to obtain gas-phase metallicities and star-formation rates from host galaxies with active star formation. From a final sample of ~ 40 emission-line galaxies, we find that light-curve corrected Type Ia supernovae are ~ 0.1 magnitudes brighter in high-metallicity hosts than in low-metallicity hosts. We also find a significant (> 3{\\sigma}) correlation between the Hubble residuals of Type Ia supernovae and the specific star-formation rate of the host galaxy. We comment on the importance of supernova/host-galaxy correlations as a source of systematic bias in future deep supernova surveys.

  20. Optical and Infrared Photometry of the Nearby Type Ia Supernovae 1999ee, 2000bh, 2000ca, and 2001ba

    E-Print Network [OSTI]

    Kevin Krisciunas; Mark M. Phillips; Nicholas B. Suntzeff; S. E. Persson; Mario Hamuy; Roberto Antezana; Pablo Candia; Alejandro Clocchiatti; Darren L. DePoy; Lisa M. Germany; Luis Gonzalez; Sergio Gonzalez; Wojtek Krzeminski; Jose Maza; Peter E. Nugent; Yulei Qiu; Armin Rest; Miguel Roth; Maximilian Stritzinger; L. -G. Strolger; Ian Thompson; T. B. Williams; Marina Wischnjewsky

    2003-11-18

    We present near infrared photometry of the Type Ia supernova 1999ee; also, optical and infrared photometry of the Type Ia SNe 2000bh, 2000ca, and 2001ba. For SNe 1999ee and 2000bh we present the first-ever SN photometry at 1.035 microns (the Y-band). We present K-corrections which transform the infrared photometry in the observer's frame to the supernova rest frame. Using our infrared K-corrections and stretch factors derived from optical photometry, we construct JHK templates which can be used to determine the apparent magnitudes at maximum if one has some data in the window -12 to +10 d with respect to T(B_max). Following up previous work on the uniformity of V minus IR loci of Type Ia supernovae of mid-range decline rates, we present unreddened loci for slow decliners. We also discuss evidence for a continuous change of color at a given epoch as a function of decline rate.

  1. Constraints on the progenitor system of the type Ia supernova 2014J from pre-explosion Hubble space telescope imaging

    SciTech Connect (OSTI)

    Kelly, Patrick L.; Fox, Ori D.; Filippenko, Alexei V.; Shen, Ken J.; Zheng, WeiKang; Graham, Melissa L.; Tucker, Brad E. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Cenko, S. Bradley [NASA/Goddard Space Flight Center, Code 662, Greenbelt, MD 20771 (United States); Prato, Lisa [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Schaefer, Gail, E-mail: pkelly@astro.berkeley.edu [The CHARA Array of Georgia State University, Mount Wilson Observatory, Mount Wilson, CA 91023 (United States)

    2014-07-20

    We constrain the properties of the progenitor system of the highly reddened Type Ia supernova (SN Ia) 2014J in Messier 82 (M82; d ? 3.5 Mpc). We determine the supernova (SN) location using Keck-II K-band adaptive optics images, and we find no evidence for flux from a progenitor system in pre-explosion near-ultraviolet through near-infrared Hubble Space Telescope (HST) images. Our upper limits exclude systems having a bright red giant companion, including symbiotic novae with luminosities comparable to that of RS Ophiuchi. While the flux constraints are also inconsistent with predictions for comparatively cool He-donor systems (T ? 35,000 K), we cannot preclude a system similar to V445 Puppis. The progenitor constraints are robust across a wide range of R{sub V} and A{sub V} values, but significantly greater values than those inferred from the SN light curve and spectrum would yield proportionally brighter luminosity limits. The comparatively faint flux expected from a binary progenitor system consisting of white dwarf stars would not have been detected in the pre-explosion HST imaging. Infrared HST exposures yield more stringent constraints on the luminosities of very cool (T < 3000 K) companion stars than was possible in the case of SN Ia 2011fe.

  2. Metabolomic profiling of the nectars of Aquilegia pubescens and <i>A. Canadensis

    SciTech Connect (OSTI)

    Noutsos, Christos; Perera, Ann M.; Nikolau, Basil J.; Seaver, Samuel M. D.; Ware, Doreen H.; Motta, Andrea

    2015-05-01

    To date, variation in nectar chemistry of flowering plants has not been studied in detail. Such variation exerts considerable influence on pollinator–plant interactions, as well as on flower traits that play important roles in the selection of a plant for visitation by specific pollinators. Over the past 60 years the Aquilegia genus has been used as a key model for speciation studies. In this study, we defined the metabolomic profiles of flower samples of two Aquilegia species, <i>A. Canadensis and <i>A. pubescens. We identified a total of 75 metabolites that were classified into six main categories: organic acids, fatty acids, amino acids, esters, sugars, and unknowns. The mean abundances of 25 of these metabolites were significantly different between the two species, providing insights into interspecies variation in floral chemistry. Using the PlantSEED biochemistry database, we found that the majority of these metabolites are involved in biosynthetic pathways. Finally, we explored the annotated genome of <i>A. coerulea, using the PlantSEED pipeline and reconstructed the metabolic network of Aquilegia. This network, which contains the metabolic pathways involved in generating the observed chemical variation, is now publicly available from the DOE Systems Biology Knowledge Base (KBase; http://kbase.us).

  3. Two Type Ia Supernovae at Redshift ~2 : Improved Classification and Redshift Determination with Medium-band Infrared Imaging

    E-Print Network [OSTI]

    Rodney, Steven A; Scolnic, Daniel M; Jones, David O; Hemmati, Shoubaneh; Molino, Alberto; McCully, Curtis; Mobasher, Bahram; Strolger, Louis-Gregory; Graur, Or; Hayden, Brian; Casertano, Stefano

    2015-01-01

    We present two supernovae (SNe) discovered with the Hubble Space Telescope (HST) in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), an HST multi-cycle treasury program. We classify both objects as Type Ia SNe and find redshifts of z = 1.80+-0.02 and 2.26 +0.02 -0.10, the latter of which is the highest redshift Type Ia SN yet seen. Using light curve fitting we determine luminosity distances and find that both objects are consistent with a standard Lambda-CDM cosmological model. These SNe were observed using the HST Wide Field Camera 3 infrared detector (WFC3-IR), with imaging in both wide- and medium-band filters. We demonstrate that the classification and redshift estimates are significantly improved by the inclusion of single-epoch medium-band observations. This medium-band imaging approximates a very low resolution spectrum (lambda/delta lambda ~ 100) which can isolate broad spectral absorption features that differentiate Type Ia SNe from their most common core collapse cousins...

  4. Final Evolution and Delayed Explosions of Spinning White Dwarfs in Single Degenerate Models for Type Ia Supernovae

    E-Print Network [OSTI]

    Benvenuto, Omar G; Kitamura, Hikaru; Hachisu, Izumi

    2015-01-01

    We study the occurrence of delayed SNe~Ia in the single degenerate (SD) scenario. We assume that a massive carbon-oxygen (CO) white dwarf (WD) accretes matter coming from a companion star, making it to spin at the critical rate. We assume uniform rotation due to magnetic field coupling. The carbon ignition mass for non-rotating WDs is M_{ig}^{NR} \\approx 1.38 M_{\\odot}; while for the case of uniformly rotating WDs it is a few percent larger (M_{ig}^{R} \\approx 1.43 M_{\\odot}). When accretion rate decreases, the WD begins to lose angular momentum, shrinks, and spins up; however, it does not overflow its critical rotation rate, avoiding mass shedding. Thus, angular momentum losses can lead the CO WD interior to compression and carbon ignition, which would induce an SN~Ia. The delay, largely due to the angular momentum losses timescale, may be large enough to allow the companion star to evolve to a He WD, becoming undetectable at the moment of explosion. This scenario supports the occurrence of delayed SNe~Ia if...

  5. Radiogenic p-isotopes from type Ia supernova, nuclear physics uncertainties, and galactic chemical evolution compared with values in primitive meteorites

    SciTech Connect (OSTI)

    Travaglio, C.; Gallino, R.; Rauscher, T.; Dauphas, N.; Röpke, F. K.; Hillebrandt, W. E-mail: claudia.travaglio@b2fh.org

    2014-11-10

    The nucleosynthesis of proton-rich isotopes is calculated for multi-dimensional Chandrasekhar-mass models of Type Ia supernovae (SNe Ia) with different metallicities. The predicted abundances of the short-lived radioactive isotopes {sup 92}Nb, {sup 97,} {sup 98}Tc, and {sup 146}Sm are given in this framework. The abundance seeds are obtained by calculating s-process nucleosynthesis in the material accreted onto a carbon-oxygen white dwarf from a binary companion. A fine grid of s-seeds at different metallicities and {sup 13}C-pocket efficiencies is considered. A galactic chemical evolution model is used to predict the contribution of SN Ia to the solar system p-nuclei composition measured in meteorites. Nuclear physics uncertainties are critical to determine the role of SNe Ia in the production of {sup 92}Nb and {sup 146}Sm. We find that, if standard Chandrasekhar-mass SNe Ia are at least 50% of all SN Ia, they are strong candidates for reproducing the radiogenic p-process signature observed in meteorites.

  6. Tangled Up in Knots: Structures of Inactivated Forms of E. coli Class Ia Ribonucleotide Reductase

    SciTech Connect (OSTI)

    Zimanyi, Christina M.; Ando, Nozomi; Brignole, Edward J.; Asturias, Francisco J.; Stubbe, JoAnne; Drennan, Catherine L. (MIT); (Scripps)

    2012-10-23

    Ribonucleotide reductases (RNRs) provide the precursors for DNA biosynthesis and repair and are successful targets for anticancer drugs such as clofarabine and gemcitabine. Recently, we reported that dATP inhibits E. coli class Ia RNR by driving formation of RNR subunits into {alpha}{sub 4}{beta}{sub 4} rings. Here, we present the first X-ray structure of a gemcitabine-inhibited E. coli RNR and show that the previously described {alpha}{sub 4}{beta}{sub 4} rings can interlock to form an unprecedented ({alpha}{sub 4}{beta}{sub 4}){sub 2} megacomplex. This complex is also seen in a higher-resolution dATP-inhibited RNR structure presented here, which employs a distinct crystal lattice from that observed in the gemcitabine-inhibited case. With few reported examples of protein catenanes, we use data from small-angle X-ray scattering and electron microscopy to both understand the solution conditions that contribute to concatenation in RNRs as well as present a mechanism for the formation of these unusual structures.

  7. Color dispersion and Milky-Way-like reddening among type Ia supernovae

    SciTech Connect (OSTI)

    Scolnic, Daniel M.; Riess, Adam G.; Rodney, Steven A.; Brout, Dillon J.; Jones, David O. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Rest, Armin [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

    2014-01-01

    Past analyses of Type Ia supernovae have identified an irreducible scatter of 5%-10% in distance, widely attributed to an intrinsic dispersion in luminosity. Another equally valid source of this scatter is intrinsic dispersion in color. Misidentification of the true source of this scatter can bias both the retrieved color-luminosity relation and cosmological parameter measurements. The size of this bias depends on the magnitude of the intrinsic color dispersion relative to the distribution of colors that correlate with distance. We produce a realistic simulation of a misattribution of intrinsic scatter and find a negative bias in the recovered color-luminosity relation, ?, of ?? ? –1.0 (?33%) and a positive bias in the equation of state parameter, w, of ?w ? +0.04 (?4%). We re-analyze current published datasets with the assumption that the distance scatter is predominantly the result of color. Unlike previous analyses, we find that the data are consistent with a Milky-Way-like reddening law (R{sub V} = 3.1) and that a Milky-Way dust model better predicts the asymmetric color-luminosity trends than the conventional luminosity scatter hypothesis. We also determine that accounting for color variation reduces the correlation between various host galaxy properties and Hubble residuals by ?20%.

  8. A Test of Tully-Fisher Distance Estimates Using Cepheids and Type Ia Supernovae

    E-Print Network [OSTI]

    T. Shanks

    1999-01-24

    We update and extend the results of Shanks (1997, MNRAS, 290, L77) by making a direct test of Tully-Fisher distance estimates to thirteen spiral galaxies with HST Cepheid distances and to ten spiral galaxies with Type Ia supernova (SNIa) distances. The results show that the Tully-Fisher distance moduli are too short with respect to the Cepheid distances by 0.46+-0.11mag and too short with respect to the SNIa distances by 0.49+-0.18mag. Combining the HST Cepheid and the best SNIa data suggests that, overall, previous Tully-Fisher distances at v~1000 kms-1 were too short by 0.43+-0.09mag, a result which is significant at the 4.6 sigma level. These data therefore indicate that previous Tully-Fisher distances should be revised upwards by 22+-5% implying, for example, a Virgo distance of 19.0+-1.8Mpc. The value of Ho from Tully-Fisher estimates is correspondingly revised downwards from Ho=84+-10kms-1Mpc-1 to Ho=69+-8kms-1Mpc-1. There is evidence that the Tully-Fisher relation at large distances is affected by Malmquist bias. In this case, we argue that Ho<50kms-1Mpc-1 cannot be ruled out by Tully-Fisher considerations.

  9. On Iron Enrichment, Star Formation, and Type Ia Supernovae in Galaxy Clusters

    E-Print Network [OSTI]

    Michael Loewenstein

    2006-05-04

    The nature of star formation and Type Ia supernovae (SNIa) in galaxies in the field and in rich galaxy clusters are contrasted by juxtaposing the build-up of heavy metals in the universe inferred from observed star formation and supernovae rate histories with data on the evolution of Fe abundances in the intracluster medium (ICM). Models for the chemical evolution of Fe in these environments are constructed, subject to observational constraints, for this purpose. While models with a mean delay for SNIa of 3 Gyr and standard initial mass function (IMF) are consistent with observations in the field, cluster Fe enrichment immediately tracks a rapid, top-heavy phase of star formation -- although transport of Fe into the ICM may be more prolonged and star formation likely continues to redshifts formation mode. Star formation is >3 times more efficient in rich clusters than in the field, mitigating the overcooling problem in numerical cluster simulations. Both the fraction of baryons cycled through stars, and the fraction of the total present-day stellar mass in the form of stellar remnants, are substantially greater in clusters than in the field.

  10. Revised photometry and color distribution of Type Ia supernovae observed at Asiago in the seventies

    E-Print Network [OSTI]

    F. Patat; R. Barbon; E. Cappellaro M. Turatto

    1996-05-29

    Following recent claims regarding possible errors in the photometry of SNe carried out at Asiago observatory during the 70's, which produced very blue $(B-V)$ color at maximum for some objects, we present the result of new CCD photometry of the sequences around 16 type Ia supernovae. Except for a few cases, e.g. SN1970J and SN1972J for which a large zero point error has been found, the new data show that the old Asiago observations have been carried out properly and that their accuracy was comparable to that expected for a photometry based on photographic transfers. This result is also substantiated by comparison with the re-calibration of some Asiago sequences made photo-electrically by Tsvetkov. New light curves of the SNe have been determined and B magnitudes and (B-V) colors at light peak derived. With the new data the color distribution of the SNe studied here becomes narrower and moves to the red by only 0.06 mag, showing no more very blue objects except for one, still uncertain, case. As far as the use of SNIa as standard candles is concerned, we show that the utilization of all SNe in the M$_B$ vs. (B-V)$^{max}_0$ plane reduces the uncertainties due to the photometry.

  11. Evidence for Microvariability in the Optical Light Curve of the Type Ia SN 2014J

    E-Print Network [OSTI]

    Bonanos, A Z

    2015-01-01

    We present results of high-cadence monitoring of the optical light curve of the nearby, Type Ia SN 2014J in M82 using the 2.3m Aristarchos telescope. $B$ and $V$-band photometry on days 15-18 after $t_{max}(B)$, obtained with a cadence of 2 min per band, reveals evidence for variability at the 0.02-0.05 mag level on timescales of 15-60 min on all four nights. The decline slope was measured to be steeper in the $B$-band than in $V$-band, and to steadily decrease in both bands from 0.15 mag/day (night 1) to 0.04 mag/day (night 4) in V and from 0.19 mag/day (night 1) to 0.06 mag/day (night 4) in B, corresponding to the onset of the secondary maximum. We propose that microvariability could be due to one or a combination of the following scenarios: the clumpiness of the ejecta, their interaction with circumstellar material, the asymmetry of the explosion, or the mechanism causing the secondary maximum in the near-infrared light curve. We encourage the community to undertake high-cadence monitoring of future, nearb...

  12. Accelerating universe from gravitational leakage into extra dimensions: confrontation with SNeIa

    E-Print Network [OSTI]

    Zong-Hong Zhu; Jailson S. Alcaniz

    2004-11-01

    There is mounting observational evidence that the expansion of our universe is undergoing an acceleration. A dark energy component has usually been invoked as the most feasible mechanism for the acceleration. However, it is desirable to explore alternative possibilities motivated by particle physics before adopting such an untested entity. In this work, we focus our attention on an acceleration mechanism: one arising from gravitational leakage into extra dimensions. We confront this scenario with high-$z$ type Ia supernovae compiled by Tonry et al. (2003) and recent measurements of the X-ray gas mass fractions in clusters of galaxies published by Allen et al. (2002,2003). A combination of the two databases gives at a 99% confidence level that $\\Omega_m=0.29^{+0.04}_{-0.02}$, $\\Omega_{rc}=0.21^{+0.08}_{-0.08}$, and $\\Omega_k=-0.36^{+0.31}_{-0.35}$, indicating a closed universe. We then constrain the model using the test of the turnaround redshift, $z_{q=0}$, at which the universe switches from deceleration to acceleration. We show that, in order to explain that acceleration happened earlier than $z_{q=0} = 0.6$ within the framework of gravitational leakage into extra dimensions, a low matter density, $\\Omega_m < 0.27$, or a closed universe is necessary.

  13. Type Ia Supernovae: Can Coriolis force break the symmetry of the gravitational confined detonation explosion mechanism?

    E-Print Network [OSTI]

    García-Senz, D; Domínguez, I; Thielemann, F K

    2015-01-01

    Nowadays the number of models aimed at explaining the Type Ia supernova phenomenon is high and discriminating between them is a must-do. In this work we explore the influence of rotation in the evolution of the nuclear flame which drives the explosion in the so called gravitational confined detonation models. Assuming that the flame starts in a point-like region slightly above the center of the white dwarf (WD) and adding a moderate amount of angular velocity to the star we follow the evolution of the deflagration using a smoothed particle hydrodynamics code. We find that the results are very dependent on the angle between the rotational axis and the line connecting the initial bubble of burned material with the center of the white dwarf at the moment of the ignition. The impact of rotation is larger for angles close to 90{\\deg} because the Coriolis force on a floating element of fluid is maximum, and its principal effect is to break the symmetry of the deflagration. Such symmetry breaking weakens the converg...

  14. The Internal Shear of Type Ia Supernova Progenitors During Accretion and Simmering

    E-Print Network [OSTI]

    Anthony L. Piro

    2008-01-07

    A white dwarf (WD) gains substantial angular momentum during the accretion process that grows it toward a Chandrasekhar mass. It is therefore expected to be quickly rotating when it ignites as a Type Ia supernova. The thermal and shearing profile are important for subsequent flame propagation. We highlight processes that could affect the WD shear, during accretion as well as during the ~1000 years of pre-explosive simmering. Baroclinic instabilities and/or the shear growth of small magnetic fields provide sufficient torque to bring the WD very close to solid body rotation during accretion. The lack of significant shear makes it difficult to grow a WD substantially past the typical Chandrasekhar mass. Once carbon ignites, a convective region spreads from the WD's center. This phase occurs regardless of progenitor scenario, and therefore it is of great interest for understanding how the WD interior is prepared before the explosive burning begins. We summarize some of the key properties of the convective region, which includes demonstrating that the mass enclosed by convection at any given time depends most sensitively on a single parameter that can be expressed as either the ratio of temperatures or densities at the top and bottom of the convection zone. At low Rossby numbers the redistribution of angular momentum by convection may result in significant shearing at the convective/non-convective boundary.

  15. SN1994D in NGC4526: a normally bright type Ia supernova

    E-Print Network [OSTI]

    Georg Drenkhahn; Tom Richtler

    1999-09-07

    SN1994D of type Ia has been suspected not to fit into the relation between decline rate, colour, and brightness. However, an individual distance of its host galaxy, NGC4526, other than that of the Virgo cluster, has not yet been published. We determined the distance by the method of globular cluster luminosity functions on the basis of HST archive data. A maximum-likelihood fit returns apparent turn-over magnitudes of 23.16+-0.16mag in V and 21.96+-0.09mag in I. The corresponding distance modulus is 30.4+-0.3mag, where the error reflects our estimation of the absolute distance scale. The absolute magnitudes (not corrected for decline rate and colour) are -18.67+-0.30mag, -18.62+-0.30mag, and -18.40+-0.30mag for B, V, and I, respectively. The corrected magnitudes are -18.69+-0.31mag, -18.69+-0.31mag, and -18.44+-0.31mag. Compared with other supernovae with reliably determined distances, SN1994D fits within the errors. It is therefore not a counter-example against a uniform decline-rate-colour-brightness relation.

  16. Gamma rays from a supernova of type Ia: SN2014J

    E-Print Network [OSTI]

    Diehl, Roland

    2015-01-01

    SN2014J is the closest supernova of type Ia that occured in the last 40 years. This provides an opportunity for unprecedented observational detail and coverage in many astronomical bands, which will help to better understand the still unknown astrophysics of these supernovae. For the first time, such an event occurs sufficiently nearby so that also gamma rays are able to contribute to such investigations. This is important, as the primary source of the supernova light is the radioactive energy from about 0.5 M$_\\odot$ of $^{56}$Ni produced in the explosion, and the gamma rays associated with this decay make the supernova shine for months. The INTEGRAL gamma-ray observatory of ESA has followed the supernova emission for almost 5 months. The characteristic gamma ray lines from the $^{56}$Ni decay chain through $^{56}$Co to $^{56}$Fe have been measured. We discuss these observations, and the implications of the measured gamma-ray line characteristics as they evolve.

  17. FIRST EVIDENCE OF GLOBULAR CLUSTER FORMATION FROM THE EJECTA OF PROMPT TYPE Ia SUPERNOVAE

    SciTech Connect (OSTI)

    Tsujimoto, Takuji [National Astronomical Observatory of Japan, Mitaka-shi, Tokyo 181-8588 (Japan); Bekki, Kenji, E-mail: taku.tsujimoto@nao.ac.jp [ICRAR, M468, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia)

    2012-06-01

    Recent spectroscopic observations of globular clusters (GCs) in the Large Magellanic Cloud (LMC) have discovered that one of the intermediate-age GCs, NGC 1718, with [Fe/H] = -0.7 has an extremely low [Mg/Fe] ratio of {approx}-0.9. We propose that NGC 1718 was formed from the ejecta of Type Ia supernovae mixed with very metal-poor ([Fe/H] <-1.3) gas about {approx}2 Gyr ago. The proposed scenario is shown to be consistent with the observed abundances of Fe-group elements such as Cr, Mn, and Ni. In addition, compelling evidence for asymptotic giant branch stars playing a role in chemical enrichment during this GC formation is found. We suggest that the origin of the metal-poor gas is closely associated with efficient gas transfer from the outer gas disk of the Small Magellanic Cloud to the LMC disk. We anticipate that the outer part of the LMC disk contains field stars exhibiting significantly low [Mg/Fe] ratios, formed through the same process as NGC 1718.

  18. An inverted AlGaAs/GaAs patterned-Ge tunnel junction cascade concentrator solar cell

    SciTech Connect (OSTI)

    Venkatasubramanian, R. )

    1993-01-01

    This report describes work to develop inverted-grown Al[sub 0.34]Ga[sub 0.66]As/GaAs cascades. Several significant developments are reported on as follows: (1) The AM1.5 1-sun total-area efficiency of the top Al[sub 0.34]Ga[sub 0.66]As cell for the cascade was improved from 11.3% to 13.2% (NREL measurement [total-area]). (2) The cycled'' organometallic vapor phase epitaxy growth (OMVPE) was studied in detail utilizing a combination of characterization techniques including Hall-data, photoluminescence, and secondary ion mass spectroscopy. (3) A technique called eutectic-metal-bonding (EMB) was developed by strain-free mounting of thin GaAs-AlGaAs films (based on lattice-matched growth on Ge substrates and selective plasma etching of Ge substrates) onto Si carrier substrates. Minority-carrier lifetime in an EMB GaAs double-heterostructure was measured as high as 103 nsec, the highest lifetime report for a freestanding GaAs thin film. (4) A thin-film, inverted-grown GaAs cell with a 1-sun AM1.5 active-area efficiency of 20.3% was obtained. This cell was eutectic-metal-bonded onto Si. (5) A thin-film inverted-grown, Al[sub 0.34]Ga[sub 0.66]As/GaAs cascade with AM1.5 efficiency of 19.9% and 21% at 1-sun and 7-suns, respectively, was obtained. This represents an important milestone in the development of an AlGaAs/GaAs cascade by OMVPE utilizing a tunnel interconnect and demonstrates a proof-of-concept for the inverted-growth approach.

  19. DC characteristics of OMVPE-grown N-p-n InGaP/InGaAsN DHBTs

    SciTech Connect (OSTI)

    Li, N.Y.; Chang, P.C.; Baca, A.G.; Xie, X.M.; Sharps, P.R.; Hou, H.Q.

    2000-01-04

    The authors demonstrate, for the first time, a functional N-p-n heterojunction bipolar transistor using a novel material, InGaAsN, with a bandgap energy of 1.2eV as the p-type base layer. A 300{angstrom}-thick In{sub x}Ga{sub 1-x}As graded layer was introduced to reduce the conduction band offset at the p-type InGaAsN base and n-type GaAs collector junction. For an emitter size of 500 {mu}m{sup 2}, a peak current gain of 5.3 has been achieved.

  20. The Effect of the Thermal Boundary Resistance on Self-Heating of AlGaN/GaN HFETs

    E-Print Network [OSTI]

    sound velocity in GaN. The cut off wave vector is given by where NA is the Avogadro number, is the mass

  1. Reliability of AlGaN/GaN high electron mobility transistors on low dislocation density bulk GaN substrate: Implications of surface step edges

    SciTech Connect (OSTI)

    Killat, N., E-mail: Nicole.Killat@bristol.ac.uk, E-mail: Martin.Kuball@bristol.ac.uk; Montes Bajo, M.; Kuball, M., E-mail: Nicole.Killat@bristol.ac.uk, E-mail: Martin.Kuball@bristol.ac.uk [Center for Device Thermography and Reliability (CDTR), H.H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Paskova, T. [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States) [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States); Materials Science and Engineering Department, North Carolina State University, Raleigh, North Carolina 27695 (United States); Evans, K. R. [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States)] [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States); Leach, J. [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States) [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States); Electrical and Computer Engineering Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Li, X.; Özgür, Ü.; Morkoç, H. [Electrical and Computer Engineering Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)] [Electrical and Computer Engineering Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Chabak, K. D.; Crespo, A.; Gillespie, J. K.; Fitch, R.; Kossler, M.; Walker, D. E.; Trejo, M.; Via, G. D.; Blevins, J. D. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States)] [Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States)

    2013-11-04

    To enable gaining insight into degradation mechanisms of AlGaN/GaN high electron mobility transistors, devices grown on a low-dislocation-density bulk-GaN substrate were studied. Gate leakage current and electroluminescence (EL) monitoring revealed a progressive appearance of EL spots during off-state stress which signify the generation of gate current leakage paths. Atomic force microscopy evidenced the formation of semiconductor surface pits at the failure location, which corresponds to the interaction region of the gate contact edge and the edges of surface steps.

  2. Testing CPT conservation using the NuMI neutrino beam with the MINOS experiment

    SciTech Connect (OSTI)

    Auty, David John; /Sussex U.

    2010-05-01

    The MINOS experiment was designed to measure neutrino oscillation parameters with muon neutrinos. It achieves this by measuring the neutrino energy spectrum and flavor composition of the man-made NuMI neutrino beam 1km after the beam is formed and again after 735 km. By comparing the two spectra it is possible to measure the oscillation parameters. The NuMI beam is made up of 7.0% {bar {nu}}{sub {mu}}, which can be separated from the {nu}{sub {mu}} because the MINOS detectors are magnetized. This makes it possible to study {bar {nu}}{sub {mu}} oscillations separately from those of muon neutrinos, and thereby test CPT invariance in the neutrino sector by determining the {bar {nu}}{sub {mu}} oscillation parameters and comparing them with those for {nu}{sub {mu}}, although any unknown physics of the antineutrino would appear as a difference in oscillation parameters. Such a test has not been performed with beam {bar {nu}}{sub {mu}} before. It is also possible to produce an almost pure {bar {nu}}{sub {mu}} beam by reversing the current through the magnetic focusing horns of the NuMI beamline, thereby focusing negatively, instead of positively charged particles. This thesis describes the analysis of the 7% {bar {nu}}{sub {mu}} component of the forward horn current NuMI beam. The {bar {nu}}{sub {mu}} of a data sample of 3.2 x 10{sup 20} protons on target analysis found 42 events, compared to a CPT conserving prediction of 58.3{sub -7.6}{sup +7.6}(stat.){sub -3.6}{sup +3.6}(syst.) events. This corresponds to a 1.9 {sigma} deficit, and a best fit value of {Delta}{bar m}{sub 32}{sup 2} = 18 x 10{sup -3} eV{sup 2} and sin{sup 2} 2{bar {theta}}{sub 23} = 0.55. This thesis focuses particularly on the selection of {bar {nu}}{sub {mu}} events, and investigates possible improvements of the selection algorithm. From this a different selector was chosen, which corroborated the findings of the original selector. The thesis also investigates how the systematic errors affect the precision of {Delta}{bar m}{sub 32}{sup 2} and sin{sup 2} 2{bar {theta}}{sub 23}. Furthermore, it describes a study to determine the gains of the PMTs via the single-photoelectron spectrum. The results were used as a crosscheck of the gains determined at higher intensities by an LED-based light-injection system.

  3. AMENDMENT OF SOLICITATION/MODIFICATlON OF CONTRACT MI54 I See Block 16C I

    National Nuclear Security Administration (NNSA)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefield Municipal GasAdministration Medal01 Sandia National 1 PAGE 1 OF2 AMENDMENTNLUF1 82 Se elBabcockMI54

  4. Adrenaline promotes cell proliferation and increases chemoresistance in colon cancer HT29 cells through induction of miR-155

    SciTech Connect (OSTI)

    Pu, Jun [Department of General Surgery, Tangdu Hospital of the Fourth Military Medical University, Xi'an 710038 (China)] [Department of General Surgery, Tangdu Hospital of the Fourth Military Medical University, Xi'an 710038 (China); Bai, Danna [Department of Cardiology, 323 Hospital of PLA, Xi'an 710054 (China)] [Department of Cardiology, 323 Hospital of PLA, Xi'an 710054 (China); Yang, Xia [Department of Teaching and Medical Administration, Tangdu Hospital of the Fourth Military Medical University, Xi'an 710038 (China)] [Department of Teaching and Medical Administration, Tangdu Hospital of the Fourth Military Medical University, Xi'an 710038 (China); Lu, Xiaozhao [Department of Nephrology, The 323 Hospital of PLA, Xi'an 710054 (China)] [Department of Nephrology, The 323 Hospital of PLA, Xi'an 710054 (China); Xu, Lijuan, E-mail: 13609296272@163.com [Department of Nephrology, The 323 Hospital of PLA, Xi'an 710054 (China)] [Department of Nephrology, The 323 Hospital of PLA, Xi'an 710054 (China); Lu, Jianguo, E-mail: lujianguo029@yahoo.com.cn [Department of General Surgery, Tangdu Hospital of the Fourth Military Medical University, Xi'an 710038 (China)] [Department of General Surgery, Tangdu Hospital of the Fourth Military Medical University, Xi'an 710038 (China)

    2012-11-16

    Highlights: Black-Right-Pointing-Pointer Adrenaline increases colon cancer cell proliferation and its resistance to cisplatin. Black-Right-Pointing-Pointer Adrenaline activates NF{kappa}B in a dose dependent manner. Black-Right-Pointing-Pointer NF{kappa}B-miR-155 pathway contributes to cell proliferation and resistance to cisplatin. -- Abstract: Recently, catecholamines have been described as being involved in the regulation of cancer genesis and progression. Here, we reported that adrenaline increased the cell proliferation and decreased the cisplatin induced apoptosis in HT29 cells. Further study found that adrenaline increased miR-155 expression in an NF{kappa}B dependent manner. HT29 cells overexpressing miR-155 had a higher cell growth rate and more resistance to cisplatin induced apoptosis. In contrast, HT29 cells overexpressing miR-155 inhibitor displayed decreased cell proliferation and sensitivity to cisplatin induced cell death. In summary, our study here revealed that adrenaline-NF{kappa}B-miR-155 pathway at least partially contributes to the psychological stress induced proliferation and chemoresistance in HT29 cells, shedding light on increasing the therapeutic strategies of cancer chemotherapy.

  5. Istanbul,Turkey & Atlanta, GA Istanbul,Turkey

    E-Print Network [OSTI]

    Frantz, Kyle J.

    Istanbul,Turkey & Atlanta, GA Istanbul,Turkey & Atlanta, GA 2012 Media, Journalism and Business for departure to Istanbul,Turkey Day 9 Depart for Istanbul; guided cultural visit upon arrival; group dinner Day business leaders; site visits to local universities Day 18 UPS and the value of logistics inTurkey Day 19

  6. Photoeffects in WO{sub 3}/GaAs electrode

    SciTech Connect (OSTI)

    Yoon, K.H.; Lee, J.W.; Cho, Y.S.; Kang, D.H.

    1996-12-01

    Photoeffects of a {ital p}-type GaAs coated with WO{sub 3} thin film have been investigated as a function of film thickness and photoresponse transients of the WO{sub 3}/GaAs electrode were studied. Also, these results were compared to those for a single {ital p}-type GaAs electrode. The photocurrent of the WO{sub 3}/GaAs electrode depended on the film thickness of the WO{sub 3}, showing an optimum photon efficiency for specimens of 800 A thickness. This is due to the existence of an effective interface state within the band gap which reduces trapping of carriers and facilitates carrier movement. For an 800-A-thick WO{sub 3} thin film deposited {ital p}-GaAs photoelectrode, the photogenerated electrons were found to move to an electrolyte at a higher positive onset potential compared with that of single {ital p}-type GaAs, which was confirmed as a result of transient behavior. {ital I}{endash}{ital V} and {ital C}{endash}{ital V} characteristics of the WO{sub 3}/GaAs electrode were also compared with those of a single {ital p}-type GaAs electrode. {copyright} {ital 1996 American Institute of Physics.}

  7. Room temperature spin transport in undoped (110) GaAs/AlGaAs quantum wells

    SciTech Connect (OSTI)

    Yokota, Nobuhide Aoshima, Yohei; Ikeda, Kazuhiro; Kawaguchi, Hitoshi

    2014-02-17

    We are reporting on our first observation of a micrometer-order electron spin transport in a (110) GaAs/AlGaAs multiple quantum well (QW) at room temperature using a space- and time-resolved Kerr rotation technique. A 37-?m transport was observed within an electron spin lifetime of 1.2?ns at room temperature when using an in-plane electric field of 1.75?kV/cm. The spatio-temporal profiles of electron spins were well reproduced by the spin drift-diffusion equations coupled with the Poisson equation, supporting the validity of the measurement. The results suggest that (110) QWs are useful as a spin transport layer for semiconductor spintronic devices operating at room temperature.

  8. Evaluation of the two-photon absorption characteristics of GaSb/GaAs quantum rings

    SciTech Connect (OSTI)

    Wagener, M. C.; Botha, J. R.; Carrington, P. J.; Krier, A.

    2014-07-28

    The optical parameters describing the sub-bandgap response of GaSb/GaAs quantum rings solar cells have been obtained from photocurrent measurements using a modulated pseudo-monochromatic light source in combination with a second, continuous photo-filling source. By controlling the charge state of the quantum rings, the photoemission cross-sections describing the two-photon sub-bandgap transitions could be determined independently. Temperature dependent photo-response measurements also revealed that the barrier for thermal hole emission from the quantum rings is significantly below the quantum ring localisation energy. The temperature dependence of the sub-bandgap photo-response of the solar cell is also described in terms of the photo- and thermal-emission characteristics of the quantum rings.

  9. Sidewall passivation for InGaN/GaN nanopillar light emitting diodes

    SciTech Connect (OSTI)

    Choi, Won Hyuck; Abraham, Michael; Yu, Shih-Ying [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); You, Guanjun; Liu, Jie; Wang, Li; Xu, Jian, E-mail: jianxu@engr.psu.edu [Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Mohney, Suzanne E., E-mail: mohney@ems.psu.edu [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2014-07-07

    We studied the effect of sidewall passivation on InGaN/GaN multiquantum well-based nanopillar light emitting diode (LED) performance. In this research, the effects of varying etch rate, KOH treatment, and sulfur passivation were studied for reducing nanopillar sidewall damage and improving device efficiency. Nanopillars prepared under optimal etching conditions showed higher photoluminescence intensity compared with starting planar epilayers. Furthermore, nanopillar LEDs with and without sulfur passivation were compared through electrical and optical characterization. Suppressed leakage current under reverse bias and four times higher electroluminescence (EL) intensity were observed for passivated nanopillar LEDs compared with unpassivated nanopillar LEDs. The suppressed leakage current and EL intensity enhancement reflect the reduction of non-radiative recombination at the nanopillar sidewalls. In addition, the effect of sulfur passivation was found to be very stable, and further insight into its mechanism was gained through transmission electron microscopy.

  10. Large linear magnetoresistance in a GaAs/AlGaAs heterostructure

    SciTech Connect (OSTI)

    Aamir, Mohammed Ali, E-mail: aamir@physics.iisc.ernet.in; Goswami, Srijit, E-mail: aamir@physics.iisc.ernet.in; Ghosh, Arindam [Department of Physics, Indian Institute of Science, Bangalore 560 012 (India); Baenninger, Matthias; Farrer, Ian; Ritchie, David A. [Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Tripathi, Vikram [Department of Theoretical Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Pepper, Michael [Department of Electrical and Electronic Engineering, University College, London WC1E 7JE (United Kingdom)

    2013-12-04

    We report non-saturating linear magnetoresistance (MR) in a two-dimensional electron system (2DES) at a GaAs/AlGaAs heterointerface in the strongly insulating regime. We achieve this by driving the gate voltage below the pinch-off point of the device and operating it in the non-equilibrium regime with high source-drain bias. Remarkably, the magnitude of MR is as large as 500% per Tesla with respect to resistance at zero magnetic field, thus dwarfing most non-magnetic materials which exhibit this linearity. Its primary advantage over most other materials is that both linearity and the enormous magnitude are retained over a broad temperature range (0.3 K to 10 K), thus making it an attractive candidate for cryogenic sensor applications.

  11. Growth of GaN@InGaN Core-Shell and Au-GaN Hybrid Nanostructures for Energy Applications

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kuykendall, Tevye; Aloni, Shaul; Jen-La Plante, Ilan; Mokari, Taleb

    2009-01-01

    We demonstrated a method to control the bandgap energy of GaN nanowires by forming GaN@InGaN core-shell hybrid structures using metal organic chemical vapor deposition (MOCVD). Furthermore, we show the growth of Au nanoparticles on the surface of GaN nanowires in solution at room temperature. The work shown here is a first step toward engineering properties that are crucial for the rational design and synthesis of a new class of photocatalytic materials. The hybrid structures were characterized by various techniques, including photoluminescence (PL), energy dispersive x-ray spectroscopy (EDS), transmission and scanning electron microscopy (TEM and SEM), and x-ray diffraction (XRD).

  12. Elastic properties of Pu metal and Pu-Ga alloys

    SciTech Connect (OSTI)

    Soderlind, P; Landa, A; Klepeis, J E; Suzuki, Y; Migliori, A

    2010-01-05

    We present elastic properties, theoretical and experimental, of Pu metal and Pu-Ga ({delta}) alloys together with ab initio equilibrium equation-of-state for these systems. For the theoretical treatment we employ density-functional theory in conjunction with spin-orbit coupling and orbital polarization for the metal and coherent-potential approximation for the alloys. Pu and Pu-Ga alloys are also investigated experimentally using resonant ultrasound spectroscopy. We show that orbital correlations become more important proceeding from {alpha} {yields} {beta} {yields} {gamma} plutonium, thus suggesting increasing f-electron correlation (localization). For the {delta}-Pu-Ga alloys we find a softening with larger Ga content, i.e., atomic volume, bulk modulus, and elastic constants, suggest a weakened chemical bonding with addition of Ga. Our measurements confirm qualitatively the theory but uncertainties remain when comparing the model with experiments.

  13. Transport properties of InGaAs/GaAs Heterostructures with {delta}-doped quantum wells

    SciTech Connect (OSTI)

    Baidus, N. V.; Vainberg, V. V.; Zvonkov, B. N.; Pylypchuk, A. S. Poroshin, V. N.; Sarbey, O. G.

    2012-05-15

    The lateral transport of electrons in single- and double-well pseudomorphic GaAs/n-InGaAs/GaAs heterostructures with quantum wells 50-100 meV deep and impurity {delta}-layers in the wells, with concentrations in the range 10{sup 11} < N{sub s} < 10{sup 12} cm{sup -2}, has been investigated. Single-well structures with a doped well at the center exhibit a nonmonotonic temperature dependence of the Hall coefficient and an increase in low-temperature electron mobility with an increase in the impurity concentration. The results obtained indicate that the impurity-band electron states play an important role in the conductivity of these structures. Involvement of the impurity band also allows to explain adequately the characteristics of the conductivity of double-well structures; in contrast to single-well structures, band bending caused by asymmetric doping is of great importance. The numerical calculations of conductivity within the model under consideration confirm these suggestions.

  14. Germanium subcells for multijunction GaInP/GaInAs/Ge solar cells

    SciTech Connect (OSTI)

    Kalyuzhnyy, N. A.; Gudovskikh, A. S.; Evstropov, V. V.; Lantratov, V. M.; Mintairov, S. A.; Timoshina, N. Kh.; Shvarts, M. Z.; Andreev, V. M.

    2010-11-15

    Photovoltaic converters based on n-GaInP/n-p-Ge heterostructures grown by the OMVPE under different conditions of formation of the p-n junction are studied. The heterostructures are intended for use as narrow-gap subcells of the GaInP/GaInAs/Ge three-junction solar cells. It is shown that, in Ge p-tn junctions, along with the diffusion mechanism, the tunneling mechanism of the current flow exists; therefore, the two-diode electrical equivalent circuit of the Ge p-n junction is used. The diode parameters are determined for both mechanisms from the analysis of both dark and 'light' current-voltage dependences. It is shown that the elimination of the component of the tunneling current allows one to increase the efficiency of the Ge subcell by {approx}1% with conversion of nonconcentrated solar radiation. The influence of the tunneling current on the efficiency of the Ge-based devices can be in practice reduced to zero at photogenerated current density of {approx}1.5 A/cm{sup 2} due to the use of the concentrated solar radiation.

  15. InGaN/GaN multiple-quantum-well light-emitting diodes with a grading InN composition suppressing the Auger recombination

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    ) In conventional InGaN/GaN light-emitting diodes (LEDs), thin InGaN quantum wells are usually adopted to mitigate recombination scales with the third power of the carrier density. As a result, the efficiency droop of the Auger recombination severely limits the LED performance. Here, we proposed and showed wide InGaN quantum wells

  16. Current crowding in GaInN / GaN LEDs grown on insulating substrates X. Guo, E. F. Schubert and J. Jahns

    E-Print Network [OSTI]

    Jahns, Jürgen

    Current crowding in GaInN / GaN LEDs grown on insulating substrates X. Guo, E. F. Schubert and J. Jahns Current crowding in mesa-structure GaInN/GaN light-emitting diodes (LEDs) grown on insulating and a saturation of the optical output power at high injection currents. It is shown that the optical power

  17. Investigation of the effect of temperature during off-state degradation of AlGaN/GaN High Electron Mobility Transistors

    E-Print Network [OSTI]

    Florida, University of

    , creating both electron traps and increasing electron tunneling through the defect states [4Investigation of the effect of temperature during off-state degradation of AlGaN/GaN High Electron 2011 a b s t r a c t AlGaN/GaN High Electron Mobility Transistors were found to exhibit a negative

  18. Mesoscopic photovoltaic effect in GaAs/Ga1-xAlxAs Aharonov-Bohm rings L. Angers, A. Chepelianskii, R. Deblock, B. Reulet, and H. Bouchiat

    E-Print Network [OSTI]

    Shepelyansky, Dima

    Mesoscopic photovoltaic effect in GaAs/Ga1-xAlxAs Aharonov-Bohm rings L. Angers, A. Chepelianskii specific dc voltage. We have investigated this photovoltaic PV effect on GaAs/Ga1-xAlxAs Aharonov is generally done by measuring the dc induced signal sometimes called photovoltaic effect which has also given

  19. Determination of two-dimensional electron and hole gas carriers in AlGaN/GaN/AlN heterostructures grown by Metal

    E-Print Network [OSTI]

    Ozbay, Ekmel

    between GaN and a sapphire substrate, the dislocation scattering mechanism and the electron spillover

  20. Assessment of radiological releases from the NuMI facility during MINOS and NOvA operations

    SciTech Connect (OSTI)

    Martens, Mike; /Fermilab

    2007-04-01

    This report makes projections of the radiological releases from the NuMI facility during operations for the MINOS and NO ?A experiments. It includes an estimate of the radionuclide levels released into the atmosphere and the estimated tritium and sodium-22 concentrations in the NuMI sump water and Fermilab pond system. The analysis was performed for NuMI operations with a beam power on target increased from the present 400 kW design up to a possible 1500 kW with future upgrades. The total number of protons on target was assumed to be 18 x 10{sup 20} after the completion of MINOS and 78 x 10{sup 20} after the completion of NO ?A.

  1. The deflagration stage of Chandrasekhar mass models for type Ia supernovae. I. Early evolution

    SciTech Connect (OSTI)

    Malone, C. M.; Woosley, S. E.; Dong, S. [Department of Astronomy and Astrophysics, The University of California, Santa Cruz, Santa Cruz, CA 95064 (United States); Nonaka, A.; Almgren, A. S.; Bell, J. B. [Center for Computational Sciences and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Zingale, M. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States)

    2014-02-10

    We present high-resolution, full-star simulations of the post-ignition phase of Type Ia supernovae using the compressible hydrodynamics code Castro. Initial conditions, including the turbulent velocity field and ignition site, are imported directly from a simulation of the last few hours of presupernova convection using a low Mach number code, Maestro. Adaptive mesh refinement allows the initial burning front to be modeled with an effective resolution of 36,864{sup 3} zones (136 m zone{sup –1}). The initial rise and expansion of the deflagration front are tracked until burning reaches the star's edge and the role of the background turbulence on the flame is investigated. The effect of artificially moving the ignition location closer to the star's center is explored. The degree to which turbulence affects the burning front decreases with increasing ignition radius since the buoyancy force is stronger at larger radii. Even central ignition—in the presence of a background convective flow field—is rapidly carried off-center as the flame is carried by the flow field. We compare our results to analytic models for burning thermals, and find that they reproduce the general trends of the bubble's size and mass, but underpredict the amount of buoyant acceleration due to simplifying assumptions of the bubble's properties. Overall, we find that the amount of mass that burns prior to flame break out is small, consistent with a gravitationally confined detonation' occurring at a later epoch, but additional burning will occur following breakout that may modify this conclusion.

  2. Reconciliation of the Surface Brightness Fluctuations and Type Ia Supernovae Distance Scales

    E-Print Network [OSTI]

    Edward A. Ajhar; John L. Tonry; John P. Blakeslee; Adam G. Riess; Brian P. Schmidt

    2001-05-21

    We present Hubble Space Telescope measurements of surface brightness fluctuations (SBF) distances to early-type galaxies that have hosted Type Ia supernovae (SNIa). The agreement in the relative SBF and SNIa multicolor light curve shape and delta-m_15 distances is excellent. There is no systematic scale error with distance, and previous work has shown that SBF and SNIa give consistent ties to the Hubble flow. However, we confirm a systematic offset of about 0.25 mag in the distance zero points of the two methods, and we trace this offset to their respective Cepheid calibrations. SBF has in the past been calibrated with Cepheid distances from the H_0 Key Project team, while SNIa have been calibrated with Cepheid distances from the team composed of Sandage, Saha, and collaborators. When the two methods are calibrated in a consistent way, their distances are in superb agreement. Until the conflict over the ``long'' and ``short'' extragalactic Cepheid distances among many galaxies is resolved, we cannot definitively constrain the Hubble constant to better than about 10%, even leaving aside the additional uncertainty in the distance to the Large Magellanic Cloud, common to both Cepheid scales. However, recent theoretical SBF predictions from stellar population models favor the Key Project Cepheid scale, while the theoretical SNIa calibration lies between the long and short scales. In addition, while the current SBF distance to M31/M32 is in good agreement with the RR Lyrae and red giant branch distances, calibrating SBF with the longer Cepheid scale would introduce a 0.3 mag offset with respect to the RR Lyrae scale.

  3. Persistent C II absorption in the normal type Ia supernova 2002fk

    SciTech Connect (OSTI)

    Cartier, Régis; Zelaya, Paula [Millennium Institute of Astrophysics, Casilla 36-D, Santiago (Chile); Hamuy, Mario; Maza, José; González, Luis; Huerta, Leonor [Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Pignata, Giuliano [Departamento Ciencias Fisicas, Universidad Andres Bello, Av. República 252, Santiago (Chile); Förster, Francisco [Center for Mathematical Modelling, Universidad de Chile, Avenida Blanco Encalada 2120, Piso 7, Santiago (Chile); Folatelli, Gaston [Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Phillips, Mark M.; Morrell, Nidia; Contreras, Carlos; Roth, Miguel; González, Sergio [Carnegie Institution of Washington, Las Campanas Observatory, Colina el Pino s/n, Casilla 601 (Chile); Krisciunas, Kevin; Suntzeff, Nicholas B. [Department of Physics and Astronomy, Texas A and M University, 4242 TAMU, College Station, TX 77843 (United States); Clocchiatti, Alejandro [Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago (Chile); Coppi, Paolo [Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States); Koviak, Kathleen, E-mail: rcartier@das.uchile.cl [Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 911901 (United States)

    2014-07-01

    We present well-sampled UBVRIJHK photometry of SN 2002fk starting 12 days before maximum light through 122 days after peak brightness, along with a series of 15 optical spectra from –4 to +95 days since maximum. Our observations show the presence of C II lines in the early-time spectra of SN 2002fk, expanding at 11,000 km s{sup –1} and persisting until 8 days past maximum light with a velocity of ?9000 km s{sup –1}. SN 2002fk is characterized by a small velocity gradient of v-dot {sub Si} {sub II}=26 km s{sup –1} day{sup –1}, possibly caused by an off-center explosion with the ignition region oriented toward the observer. The connection between the viewing angle of an off-center explosion and the presence of C II in the early-time spectrum suggests that the observation of C II could be also due to a viewing angle effect. Adopting the Cepheid distance to NGC 1309 we provide the first H {sub 0} value based on near-infrared (near-IR) measurements of a Type Ia supernova (SN) between 63.0 ± 0.8 (±3.4 systematic) and 66.7 ± 1.0 (±3.5 systematic) km s{sup –1} Mpc{sup –1}, depending on the absolute magnitude/decline rate relationship adopted. It appears that the near-IR yields somewhat lower (6%-9%) H {sub 0} values than the optical. It is essential to further examine this issue by (1) expanding the sample of high-quality near-IR light curves of SNe in the Hubble flow, and (2) increasing the number of nearby SNe with near-IR SN light curves and precise Cepheid distances, which affords the promise to deliver a more precise determination of H {sub 0}.

  4. The MiMeS Survey of Magnetism in Massive Stars: Introduction and overview

    E-Print Network [OSTI]

    Wade, G A; Alecian, E; Grunhut, J H; Petit, V; de Batz, B; Bohlender, D A; Cohen, D H; Henrichs, H F; Kochukhov, O; Landstreet, J D; Manset, N; Martins, F; Mathis, S; Oksala, M E; Owocki, S P; Rivinius, Th; Shultz, M E; Sundqvist, J O; Townsend, R H D; ud-Doula, A; Bouret, J -C; Braithwaite, J; Briquet, M; Carciofi, A C; David-Uraz, A; Folsom, C P; Fullerton, A W; Leroy, B; Marcolino, W L F; Moffat, A F J; Nazé, Y; Aurière, M; Bagnulo, S; Bailey, J D; Barbá, R H; Blazère, A; Böhm, T; Catala, C; Donati, J -F; Ferrario, L; Harrington, D; Howarth, I D; Ignace, R; Kaper, L; Lüftinger, T; Prinja, R; Vink, J S; Weiss, W W; Yakunin, I

    2015-01-01

    The MiMeS project is a large-scale, high resolution, sensitive spectropolarimetric investigation of the magnetic properties of O and early B type stars. Initiated in 2008 and completed in 2013, the project was supported by 3 Large Program allocations, as well as various programs initiated by independent PIs and archival resources. Ultimately, over 4800 circularly polarized spectra of 560 O and B stars were collected with the instruments ESPaDOnS at the Canada-France-Hawaii Telescope, Narval at the T\\'elescope Bernard Lyot, and HARPSpol at the European Southern Observatory La Silla 3.6m telescope, making MiMeS by far the largest systematic investigation of massive star magnetism ever undertaken. In this paper, the first in a series reporting the general results of the survey, we introduce the scientific motivation and goals, describe the sample of targets, review the instrumentation and observational techniques used, explain the exposure time calculation designed to provide sensitivity to surface dipole fields...

  5. Upgrade of the Minos+ Experiment Data Acquisition for the High Energy NuMI Beam Run

    E-Print Network [OSTI]

    William Badgett; Steve R. Hahn; Donatella Torretta; Jerry Meier; Jeffrey Gunderson; Denise Osterholm; David Saranen

    2015-06-06

    The Minos+ experiment is an extension of the Minos experiment at a higher energy and more intense neutrino beam, with the data collection having begun in the fall of 2013. The neutrino beam is provided by the Neutrinos from the Main Injector (NuMI) beam-line at Fermi National Accelerator Laboratory (Fermilab). The detector apparatus consists of two main detectors, one underground at Fermilab and the other in Soudan, Minnesota with the purpose of studying neutrino oscillations at a base line of 735 km. The original data acquisition system has been running for several years collecting data from NuMI, but with the extended run from 2013, parts of the system needed to be replaced due to obsolescence, reliability problems, and data throughput limitations. Specifically, we have replaced the front-end readout controllers, event builder, and data acquisition computing and trigger processing farms with modern, modular and reliable devices with few single points of failure. The new system is based on gigabit Ethernet TCP/IP communication to implement the event building and concatenation of data from many front-end VME readout crates. The simplicity and partitionability of the new system greatly eases the debugging and diagnosing process. The new system improves throughput by about a factor of three compared to the old system, up to 800 megabits per second, and has proven robust and reliable in the current run.

  6. Atomistic description of the electronic structure of InxGa1xAs alloys and InAsGaAs superlattices

    E-Print Network [OSTI]

    Kent, Paul

    quantum-wells15,20 (InxGa1 xAs)n /InP on InP and (InxGa1 xAs)n /GaAs on GaAs, and v GaAs-embedded InAs quantum dots.21­23 We wish to provide a uniform the- oretical description of the electronic structure-period dependence of the band offsets and interband transitions of InAs/GaAs systems on InP and GaAs substrates. DOI

  7. Improved hole distribution in InGaN/GaN light-emitting diodes with graded thickness quantum barriers

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    is 48.3%. Moreover, the light output power was enhanced from 770 mW for the ETQB LEDs to 870 m; accepted 3 June 2013; published online 19 June 2013) InGaN/GaN light-emitting diodes (LEDs) with graded , which is much smaller than that of the conventional equal-thickness quantum barriers (ETQB) LED, which

  8. Low-frequency noise in GaNAlGaN heterostructure field-effect transistors at cryogenic temperatures

    E-Print Network [OSTI]

    Pala, Nezih

    that the 1/f noise in GaN/AlGaN HFETs might be caused by electron tunneling from the channel to the traps was practically independent of the frequency of analysis. The model linking this maximum to the electron tunneling Department of Electrical, Computer, and Systems Engineering and Center for Integrated Electronics

  9. Development of GaAs/Si and GaAs/Si monolithic structures for future space solar cells

    SciTech Connect (OSTI)

    Spitzer, M.B.; Vernon, S.M.; Wolfson, R.G.; Tobin, S.P.

    1984-01-01

    The results of heteroepitaxial growth of GaAs and GaAlAs directly on Si are presented, and applications to new cell structures are suggested. The novel feature is the elimination of a Ge lattice transition region. This feature not only reduces the cost of substrate preparation, but also makes possible the fabrication of high efficiency monolithic cascade structures. All films to be discussed were grown by organometallic chemical vapor deposition at atmospheric pressure. This process yielded reproducible, large-area films of GaAs, grown directly on Si, that are tightly adherent and smooth, and are characterized by a defect density of 5 x 10(6) power/sq cm. Preliminary studies indicate that GaAlAs can also be grown in this way. A number of promising applications are suggested. Certainly these substrates are ideal for low-weight GaAs space solar ells. For very high efficiency, the absence of Ge makes the technology attractive for GaAlAs/Si monolithic cascades, in which the Si substrates would first be provided with a suitable p/n junction. An evaluation of a three bandgap cascade consisting of appropriately designed GaAlAs/GaAs/Si layers is also presented.

  10. Wavelength-resolved low-frequency noise of GaInN/GaN green light emitting diodes

    E-Print Network [OSTI]

    Wetzel, Christian M.

    Wavelength-resolved low-frequency noise of GaInN/GaN green light emitting diodes S. L. Rumyantseva well light emitting diodes. The light intensity noise was measured as a function of wavelength within the light emitting diode spectral emission line. The spectral noise density is found to increase

  11. GaAs-based self-aligned laser incorporating InGaP opto-electronic confinement layer

    E-Print Network [OSTI]

    be well suited for exploitation of long wavelength quantum dot and dilute nitride technology, resulting in single lateral mode emission from an In0.17Ga0.83As double quantum well laser. Introduction: Lasers based on the GaAs materials system offer advan- tages over their InP counterparts, such as the use

  12. Improved performance of In,,Ga...As/GaAs quantum dot solar cells via light scattering by nanoparticles

    E-Print Network [OSTI]

    Yu, Edward T.

    of QDs in the context of our work is attractive for achieving long wavelength absorption in solar cells enhancement at all infrared wave- lengths in the device photocurrent spectrum. Epitaxial layer structuresImproved performance of In,,Ga...As/GaAs quantum dot solar cells via light scattering

  13. Output Harmonic Termination Techniques for AlGaN/GaN HEMT Power Amplifiers Using Active Integrated Antenna Approach

    E-Print Network [OSTI]

    Itoh, Tatsuo

    Output Harmonic Termination Techniques for AlGaN/GaN HEMT Power Amplifiers Using Active Integrated 1200, Los Angeles, CA 90045 Abstract -- In this paper, effects of output harmonic terminations on PAE termination, we observe a substantial increase in PAE and output power. Further, we demonstrate the high

  14. SnO2 functionalized AlGaN/GaN high electron mobility transistor for hydrogen sensing applications

    E-Print Network [OSTI]

    Florida, University of

    for spacecraft and other long-term sensing applications. However, hydrogen is a dangerous gas for storage for monitoring leakage of hydrogen storage equipment and fuel tanks for spacecraft and hydrogen fuel cellSnO2 functionalized AlGaN/GaN high electron mobility transistor for hydrogen sensing applications

  15. Mn-doped Ga(As,P) and (Al,Ga)As ferromagnetic semiconductors: Electronic structure calculations 

    E-Print Network [OSTI]

    Masek, J.; Kudrnovsky, J.; Maca, F.; Sinova, Jairo; MacDonald, A. H.; Campion, R. P.; Gallagher, B. L.; Jungwirth, T.

    2007-01-01

    A remarkable progress towards functional ferromagnetic semiconductor materials for spintronics has been achieved in p-type (Ga,Mn)As. Robust hole-mediated ferromagnetism has, however, been observed also in other III-V hosts such as antimonides, Ga...

  16. DESIGN, GROWTH, FABRICATION AND CHARACTERIZATION OF HIGH-BAND GAP InGaN/GaN SOLAR CELLS

    E-Print Network [OSTI]

    Honsberg, Christiana

    photovoltaic efficiency of 39% at 236 suns is achieved by a triple-junction GaInP- GaInAs-Ge tandem solar cell [1]. While the achievable efficiency of triple-junction tandem solar cells is restricted to about 40% [2], modeling results show that a tandem solar cell of five junctions or greater, or an equivalent

  17. Progress toward technology transition of GaInP{sub 2}/GaAs/Ge multijunction solar cells

    SciTech Connect (OSTI)

    Keener, D.N.; Marvin, D.C.; Brinker, D.J.; Curtis, H.B.; Price, P.M.

    1997-12-31

    The objective of the joint WL/PL/NASA Multijunction Solar Cell Manufacturing Technology (ManTech) Program is to scale up high efficiency GaInP{sub 2}/GaAs/Ge multijunction solar cells to production size, quantity, and yield while limiting the production cost/Watt ($/W) to 15% over GaAs cells. Progress made by the program contractors, Spectrolab and TECSTAR, include, respectively, best cell efficiencies of 25.76% and 24.7% and establishment of 24.2% and 23.8% lot average efficiency baseline designs. The paper also presents side-by-side testing results collected by Phillips Laboratory and NASA Lewis on Phase 1 deliverable cells, which shows compliance with program objectives. Cell performance, pre- and post-radiation, and temperature coefficient results on initial production GaInP{sub 2}/GaAs/Ge solar cells will be presented.

  18. cis-and trans-Regulation of miR163 and Target Genes Confers Natural Variation of Secondary Metabolites in Two Arabidopsis

    E-Print Network [OSTI]

    Tholl, Dorothea

    involved in secondary metabolite biosynthetic pathways that are inducible by a fungal elicitor, alamethicin and secondary metabolite profiles. We suggest that cis- and trans-regulation of miRNA and other genes providescis- and trans-Regulation of miR163 and Target Genes Confers Natural Variation of Secondary

  19. Curcumin promotes apoptosis in A549/DDP multidrug-resistant human lung adenocarcinoma cells through an miRNA signaling pathway

    SciTech Connect (OSTI)

    Zhang, Jian, E-mail: zhangjian197011@yahoo.com [Department of Respiratory Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032 (China)] [Department of Respiratory Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032 (China); Zhang, Tao [Department of Thoracic Surgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038 (China)] [Department of Thoracic Surgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038 (China); Ti, Xinyu; Shi, Jieran; Wu, Changgui; Ren, Xinling [Department of Respiratory Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032 (China)] [Department of Respiratory Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032 (China); Yin, Hong, E-mail: yinnhong@yahoo.com [The Medical Image Center, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032 (China)] [The Medical Image Center, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032 (China)

    2010-08-13

    Research highlights: {yields} Curcumin had anti-cancer effects on A549/DDP multidrug-resistant human lung adenocarcinoma cells {yields} Curcumin promotes apoptosis in A549/DDP cells through a miRNA signaling pathway {yields} Curcumin induces A549/DDP cell apoptosis by downregulating miR-186* {yields} miR-186* may serve as a potential gene therapy target for refractory lung cancer that is sensitive to curcumin -- Abstract: Curcumin extracted from the rhizomes of Curcuma longa L. has been shown to have inhibitory effects on cancers through its anti-proliferative and pro-apoptotic activities. Emerging evidence demonstrates that curcumin can overcome drug resistance to classical chemotherapies. Thus, the mechanisms underlying the anti-tumor activities of curcumin require further study. In our study, we first demonstrated that curcumin had anti-cancer effects on A549/DDP multidrug-resistant human lung adenocarcinoma cells. Further studies showed that curcumin altered miRNA expression; in particular, significantly downregulated the expression of miR-186* in A549/DDP. In addition, transfection of cells with a miR-186* inhibitor promoted A549/DDP apoptosis, and overexpression of miR-186* significantly inhibited curcumin-induced apoptosis in A549/DDP cells. These observations suggest that miR-186* may serve as a potential gene therapy target for refractory lung cancer that is sensitive to curcumin.

  20. Systematic uncertainties associated with the cosmological analysis of the first Pan-STARRS1 type Ia supernova sample

    SciTech Connect (OSTI)

    Scolnic, D.; Riess, A.; Brout, D.; Rodney, S. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Rest, A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Huber, M. E.; Tonry, J. L. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Foley, R. J.; Chornock, R.; Berger, E.; Soderberg, A. M.; Stubbs, C. W.; Kirshner, R. P.; Challis, P.; Czekala, I.; Drout, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Narayan, G. [Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138 (United States); Smartt, S. J.; Botticella, M. T. [Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, Belfast BT7 1NN (United Kingdom); Schlafly, E. [Max Planck Institute for Astronomy, Konigstuhl 17, D-69117 Heidelberg (Germany); and others

    2014-11-01

    We probe the systematic uncertainties from the 113 Type Ia supernovae (SN Ia) in the Pan-STARRS1 (PS1) sample along with 197 SN Ia from a combination of low-redshift surveys. The companion paper by Rest et al. describes the photometric measurements and cosmological inferences from the PS1 sample. The largest systematic uncertainty stems from the photometric calibration of the PS1 and low-z samples. We increase the sample of observed Calspec standards from 7 to 10 used to define the PS1 calibration system. The PS1 and SDSS-II calibration systems are compared and discrepancies up to ?0.02 mag are recovered. We find uncertainties in the proper way to treat intrinsic colors and reddening produce differences in the recovered value of w up to 3%. We estimate masses of host galaxies of PS1 supernovae and detect an insignificant difference in distance residuals of the full sample of 0.037 ± 0.031 mag for host galaxies with high and low masses. Assuming flatness and including systematic uncertainties in our analysis of only SNe measurements, we find w =?1.120{sub ?0.206}{sup +0.360}(Stat){sub ?0.291}{sup +0.269}(Sys). With additional constraints from Baryon acoustic oscillation, cosmic microwave background (CMB) (Planck) and H {sub 0} measurements, we find w=?1.166{sub ?0.069}{sup +0.072} and ?{sub m}=0.280{sub ?0.012}{sup +0.013} (statistical and systematic errors added in quadrature). The significance of the inconsistency with w = –1 depends on whether we use Planck or Wilkinson Microwave Anisotropy Probe measurements of the CMB: w{sub BAO+H0+SN+WMAP}=?1.124{sub ?0.065}{sup +0.083}.

  1. Hubble Space Telescope spectra of the type Ia supernova SN 2011fe: A low-energy delayed detonation of a white dwarf with Zsolar

    E-Print Network [OSTI]

    Mazzali, Paolo; Hachinger, Stephan; Ellis, Richard; Nugent, Peter E; Howell, D Andrew; Gal-Yam, Avishay; Maguire, Kate; Cooke, Jeff; Thomas, Rollin

    2013-01-01

    Hubble Space Telescope spectroscopic observations of the nearby type Ia supernova (SN Ia) SN 2011fe, taken on 10 epochs from -13.5 to +41 days relative to B-band maximum light, and spanning the far-ultraviolet (UV) to the near-infrared (IR) are presented. This spectroscopic coverage makes SN 2011fe the best-studied local SN Ia to date. SN 2011fe is a typical moderately-luminous SN Ia with no evidence for dust extinction. Its near-UV spectral properties are representative of a larger sample of local events studied in Maguire et al. (2012). As a result, conclusions inferred from our detailed investigations are likely representative of those for other normal SNe Ia. The near-UV to optical spectra of SN 2011fe are modelled with a Monte Carlo radiative transfer code using the technique of 'abundance tomography', providing tight constraints on the density structure and abundance stratification of the event. SN 2011fe was a relatively weak explosion, with moderate Fe-group yields. Although its density structure is c...

  2. miR-206 is down-regulated in breast cancer and inhibits cell proliferation through the up-regulation of cyclinD2

    SciTech Connect (OSTI)

    Zhou, Jing; Tian, Ye; Li, Juan; Lu, Binbin; Sun, Ming; Zou, Yanfen; Kong, Rong; Luo, Yanhong; Shi, Yongguo; Wang, Keming; Ji, Guozhong

    2013-04-05

    Highlights: ? miR-206 was downexpressed in tumor samples compared with matched normal samples. ? Enhanced expression of miR-206 could inhibit breast cancer growth in vitro. ? Luciferase confirmed miR-206 functions as an anti-oncogene by targeting cyclinD2. ? A reverse correlation between miR-206 and cyclinD2 in breast cancer was found. -- Abstract: MicroRNAs act as important gene regulators in human genomes, and their aberrant expression is linked to many malignancies. Aberrant expression of miR-206 has been frequently reported in cancer studies; however, the role and mechanism of its function in breast cancer remains unclear. Quantitative real-time PCR was performed to detect the relative expression levels of miR-206 in breast cancer and normal breast tissues. Lower expression of miR-206 in breast cancer tissues was associated with larger tumour size and a more advanced clinical stage. Further in vitro observations showed that the enforced expression of miR-206 in MCF-7 breast cancer cells inhibited cell growth by blocking the G1/S transition and suppressed cell proliferation and colony formation, implying that miR-206 functions as a tumour suppressor in the progression of breast cancer. Interestingly, Luciferase assays first revealed that miR-206 inhibited cyclinD2 expression by targeting two binding sites in the 3?-untranslated region of cyclinD2 mRNA. qRT-PCR and Western blot assays verified that miR-206 reduced cyclinD2 expression at both the mRNA and protein levels. A reverse correlation between miR-206 and cyclinD2 expression was noted in breast cancer tissues. Altogether, our results identify a crucial tumour suppressive role of miR-206 in the progression of breast cancer, at least partly via up-regulation of the expression of cyclinD2, and suggest that miR-206 might be a candidate prognostic predictor or an anticancer therapeutic target for breast cancer patients.

  3. Nearby Supernova Factory Observations of SN 2005gj: Another TypeIa Supernova in a Massive Circumstellar Envelope

    SciTech Connect (OSTI)

    Aldering, G.; Antilogus, P.; Bailey, S.; Baltay, C.; Bauer, A.; Blanc, N.; Bongard, S.; Copin, Y.; Gangler, E.; Gilles, S.; Kessler, R.; Kocevski, D.; Lee, B.C.; Loken, S.; Nugent, P.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigaudier, G.; Scalzo, R.; Smadja, G.; Thomas, R.C.; Wang, L.; Weaver, B.A.; Rabinowitz, D.; Bauer, A.

    2006-06-01

    We report the independent discovery and follow-up observations of supernova 2005gj by the Nearby Supernova Factory. This is the second confirmed case of a ''hybrid'' Type Ia/IIn supernova, which like the prototype SN 2002ic, we interpret as the explosion of a white dwarf interacting with a circumstellar medium. Our early-phase photometry of SN 2005gj shows that the strength of the interaction between the supernova ejecta and circumstellar material is much stronger than for SN 2002ic. Our .rst spectrum shows a hot continuum with broad and narrow H{alpha} emission. Later spectra, spanning over 4 months from outburst, show clear Type Ia features combined with broad and narrow H{gamma}, H{beta},H{alpha} and He I {lambda}{lambda}5876,7065 in emission. At higher resolution, P Cygni profiles are apparent. Surprisingly, we also observe an inverted P Cygni profile for [O III] {lambda}5007. We find that the lightcurve and measured velocity of the unshocked circumstellar material imply mass loss as recently as 8 years ago. This is in contrast to SN 2002ic, for which an inner cavity in the circumstellar material was inferred. Within the context of the thin-shell approximation, the early lightcurve is well-described by a flat radial density profile for the circumstellar material. However, our decomposition of the spectra into Type Ia and shock emission components allows for little obscuration of the supernova, suggesting an aspherical or clumpy distribution for the circumstellar material. We suggest that the emission line velocity profiles arise from electron scattering rather than the kinematics of the shock. This is supported by the inferred high densities, and the lack of evidence for evolution in the line widths. Ground- and space-based photometry, and Keck spectroscopy, of the host galaxy are used to ascertain that the host galaxy has low metallicity (Z/Z{sub {circle_dot}} < 0.3; 95% confidence) and that this galaxy is undergoing a significant star formation event that began roughly 200 {+-} 70 Myr ago. We discuss the implications of these observations for progenitor models and cosmology using Type Ia supernovae.

  4. The Impact of Supernovae of Type Ia on Large Scales through the Secular Evolution of their Rate

    E-Print Network [OSTI]

    Laura Greggio

    2004-10-07

    A straightforward formalism to evaluate the impact of Type Ia Supernovae on large scale astrophysical issues is presented, together with analytical formulations for the SNIa rate following an instantaneous burst of Star Formation, for both single and double degenrates SNIa progenitors' models. Some applications of the parametrized formalism are illustrated. In particular, it is shown that the current SNIa rates measured in early and late type galaxies, as well as the Fe Mass-to-Light ratio in clusters of galaxies, favour the double degenerate model.

  5. Ferromagnetism in undoped One-dimensional GaN Nanowires

    SciTech Connect (OSTI)

    Jeganathan, K. E-mail: jagan@physics.bdu.ac.in; Purushothaman, V.; Debnath, R.; Arumugam, S.

    2014-05-15

    We report an intrinsic ferromagnetism in vertical aligned GaN nanowires (NW) fabricated by molecular beam epitaxy without any external catalyst. The magnetization saturates at ?0.75 × emu/gm with the applied field of 3000 Oe for the NWs grown under the low-Gallium flux of 2.4 × 10{sup ?8} mbar. Despite a drop in saturation magnetization, narrow hysteresis loop remains intact regardless of Gallium flux. Magnetization in vertical standing GaN NWs is consistent with the spectral analysis of low-temperature photoluminescence pertaining to Ga-vacancies associated structural defects at the nanoscale.

  6. Characterization of Zns-GaP Naon-composites

    SciTech Connect (OSTI)

    Todd, V.

    1993-12-09

    It proved possible to produce consistent, high-quality nanocrystalline ZnS powders with grain sizes as small as 8 nm. These powders are nano-porous and are readily impregnated with GaP precursor, although inconsistently. Both crystal structure and small grain size of the ZnS can be maintained through the use of GaP. Heat treatment of the impregnated powders results in a ZnS-GaP composite structure where the grain sizes of the phases are on the order of 10--20 nm. Conventional powder processing should be able to produce optically dense ceramic compacts with improved mechanical properties and suitable IR transmission.

  7. Office of Student Financial Aid The Welcome Center 42 West Warren P.O. Box 2340 Detroit, MI 48202-0340 313-577-2100 Fax: 313-577-6648

    E-Print Network [OSTI]

    Finley Jr., Russell L.

    · Detroit, MI 48202-0340 · 313-577-2100 · Fax: 313-577-6648 studentservice@wayne.edu · wayne: OFFICE OF STUDENT FINANCIAL AID · The Welcome Center · P. O. Box 2340 · 42 West Warren · Detroit, MI

  8. Office of Student Financial Aid The Welcome Center 42 West Warren P.O. Box 2340 Detroit, MI 48202-0340 313-577-2100 Fax: 313-577-6648

    E-Print Network [OSTI]

    Finley Jr., Russell L.

    · Detroit, MI 48202-0340 · 313-577-2100 · Fax: 313-577-6648 studentservice@wayne.edu · www FINANCIAL AID · The Welcome Center · P. O. Box 2340 · 42 West Warren · Detroit, MI 48202-0340 If this form

  9. Office of Student Financial Aid The Welcome Center 42 West Warren P.O. Box 2340 Detroit, MI 48202-0340 313-577-2100 Fax: 313-577-6648

    E-Print Network [OSTI]

    Finley Jr., Russell L.

    · Detroit, MI 48202-0340 · 313-577-2100 · Fax: 313-577-6648 studentservice@wayne.edu · www OF STUDENT FINANCIAL AID · The Welcome Center · P. O. Box 2340 · 42 West Warren · Detroit, MI 48202-0340 3

  10. Office of Student Financial Aid The Welcome Center 42 West Warren P.O. Box 2340 Detroit, MI 48202-0340 313-577-2100 Fax: 313-577-6648

    E-Print Network [OSTI]

    Finley Jr., Russell L.

    · Detroit, MI 48202-0340 · 313-577-2100 · Fax: 313-577-6648 studentservice@wayne.edu · wayne · Detroit, MI 48202-0340 Student's First Name 9-digit WSU Student ID # Student's Last Name Phone Number 3

  11. NUEX16 Office of Student Financial Aid The Welcome Center 42 West Warren P.O. Box 2340 Detroit, MI 48202-0340 313-577-2100 Fax: 313-577-6648

    E-Print Network [OSTI]

    Finley Jr., Russell L.

    · Detroit, MI 48202-0340 · 313-577-2100 · Fax: 313-577-6648 studentservice@wayne.edu · wayne FINANCIAL AID · The Welcome Center · P. O. Box 2340 · 42 West Warren · Detroit, MI 48202-0340 Student

  12. Office of Student Financial Aid The Welcome Center 42 West Warren P.O. Box 2340 Detroit, MI 48202-0340 313-577-2100 Fax: 313-577-6648

    E-Print Network [OSTI]

    Finley Jr., Russell L.

    · Detroit, MI 48202-0340 · 313-577-2100 · Fax: 313-577-6648 studentservice@wayne.edu · www · Detroit, MI 48202-0340 If this form is required it will be listed in Pipeline, under "My Requirements" 3

  13. Office of Student Financial Aid The Welcome Center 42 West Warren P.O. Box 2340 Detroit, MI 48202-0340 313-577-2100 Fax: 313-577-6648

    E-Print Network [OSTI]

    Finley Jr., Russell L.

    · Detroit, MI 48202-0340 · 313-577-2100 · Fax: 313-577-6648 studentservice@wayne.edu · www Warren · Detroit, MI 48202-0340 If this form is required it will be listed in Pipeline, under "My

  14. Manuscript was received April 15, 2007. Irina Hossain is with the Department of Electrical and Computer Engineering, Wayne State University, Detroit, MI. Phone: 651-815-5828; Fax: 651-

    E-Print Network [OSTI]

    Mahmud, Syed Masud

    and Computer Engineering, Wayne State University, Detroit, MI. Phone: 651-815-5828; Fax: 651- 305-4549; e State University, Detroit, MI. Phone: 313-577-3855; Fax: 313-577-5845; e-mail: smahmud

  15. Office of Student Financial Aid The Welcome Center 42 West Warren P.O. Box 2340 Detroit, MI 48202-0340 313-577-2100 Fax: 313-577-6648

    E-Print Network [OSTI]

    Finley Jr., Russell L.

    · Detroit, MI 48202-0340 · 313-577-2100 · Fax: 313-577-6648 studentservice@wayne.edu · wayne Warren · Detroit, MI 48202-0340 Student's First Name 9-digit WSU Student ID # Student's Last Name Phone

  16. CTFS16 Office of Student Financial Aid The Welcome Center 42 West Warren P.O. Box 2340 Detroit, MI 48202-0340 313-577-2100 Fax: 313-577-6648

    E-Print Network [OSTI]

    Finley Jr., Russell L.

    · Detroit, MI 48202-0340 · 313-577-2100 · Fax: 313-577-6648 studentservice@wayne.edu · wayne · Detroit, MI 48202-0340 3/2015 Student's First Name 9-digit WSU Student ID # Student's Last Name Phone

  17. VRHS14 Office of Student Financial Aid The Welcome Center 42 West Warren P.O. Box 2340 Detroit, MI 48202-0340 313-577-2100 Fax: 313-577-6648

    E-Print Network [OSTI]

    Finley Jr., Russell L.

    · Detroit, MI 48202-0340 · 313-577-2100 · Fax: 313-577-6648 studentservice@wayne.edu · www: OFFICE OF STUDENT FINANCIAL AID · The Welcome Center · P. O. Box 2340 · 42 West Warren · Detroit, MI

  18. Indium distribution at the interfaces of (Ga,In)(N,As)/GaAs quantum wells

    SciTech Connect (OSTI)

    Luna, E.; Ishikawa, F.; Batista, P. D.; Trampert, A. [Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, D-10117, Berlin (Germany)

    2008-04-07

    The indium distribution across (Ga,In)(N,As) quantum wells is determined by using transmission electron microscopy techniques. Inside the quantum well, the indium distribution is well described by Muraki's segregation model; however, it fails in reflecting the concentration at the interfaces. To describe them, we propose a sigmoidal law which defines the smooth variation of the indium concentration with the position and provides a systematic and quantitative characterization of the interfaces. The thermal stability of the interfaces and their interplay with segregation effects are discussed. A connection between the high thermal robustness of the interfaces and the inherent thermodynamic miscibility gap of the alloy is suggested.

  19. Local Structures and Interface Morphology of InGaAsN Thin Films Grown on GaAs

    SciTech Connect (OSTI)

    Allerman, A.A.; Chen, J.G.; Geisz, J.F.; Huang, S.; Hulbert, S.L.; Jones, E.D.; Kao, Y.H.; Kurtz, S.; Kurtz, S.R.; Olson, J.M.; Soo, Y.L.

    1999-02-23

    The compound semiconductor system InGaAsN exhibits many intriguing properties which are particularly useful for the development of innovative high efficiency thin film solar cells and long wavelength lasers. The bandgap in these semiconductors can be varied by controlling the content of N and In and the thin films can yet be lattice-matched to GaAs. In the present work, x-ray absorption fine structure (XAFS) and grazing incidence x-ray scattering (GIXS) techniques have been employed to probe the local environment surrounding both N and In atoms as well as the interface morphology of InGaAsN thin films epitaxially grown on GaAs. The soft x-ray XAFS results around nitrogen K-edge reveal that N is in the sp{sup 3} hybridized bonding configuration in InGaAsN and GaAsN, suggesting that N impurities most likely substitute for As sites in these two compounds. The results of In K-edge XAFS suggest a possible trend of a slightly larger coordination number of As nearest neighbors around In atoms in InGaAsN samples with a narrower bandgap whereas the In-As interatomic distance remains practically the same as in InAs within the experimental uncertainties. These results combined suggest that N-substitution of the As sites plays an important role of bandgap-narrowing while in the meantime counteracting the compressive strain caused by In-doping. Grazing incidence x-ray scattering (GIXS) experiments verify that InGaAsN thin films can indeed form very smooth interfaces with GaAs yielding an average interfacial roughness of 5-20{angstrom}.

  20. Network Modeling Identifies Molecular Functions Targeted by miR-204 to Suppress Head and Neck Tumor

    E-Print Network [OSTI]

    Gerstein, Mark

    Network Modeling Identifies Molecular Functions Targeted by miR-204 to Suppress Head and Neck Tumor targets predicted by sequence-alignment databases and the relative low accuracy of such predictions which with tumor progression in squamous cell carcinoma of the head and neck (HNSCC). We further demonstrate

  1. Corrosion mechanisms of low level vitrified radioactive waste in a loamy soil M.I. Ojovan1

    E-Print Network [OSTI]

    Sheffield, University of

    Corrosion mechanisms of low level vitrified radioactive waste in a loamy soil M.I. Ojovan1 , W-sodium content radioactive waste borosilicate glass buried in a loamy soil (glass K-26) and in an open testing. This mechanism is likely to remain dominant until the decay of 137 Cs in the glass is below exemption levels

  2. A trans-homologue interaction between reciprocally imprinted miR-127 and Rtl1 regulates placenta development

    E-Print Network [OSTI]

    Ito, Mitsuteru; Sferruzzi-Perri, Amanda N.; Edwards, Carol A.; Adalsteinsson, Bjorn T.; Allen, Sarah E.; Loo, Tsui-Han; Kitazawa, Moe; Kaneko-Ishino, Tomoko; Ishino, Fumitoshi; Stewart, Colin L.; Ferguson-Smith, Anne C.

    2015-07-02

    ability of small molecules like oxygen to transfer by passive diffusion from mother to fetus (Laga et al., 1973). The TDC and SDC values of the mutant placentae indicate that ?miR-127 mice have a higher diffusive capacity than WTs and conversely...

  3. THE DARK SIDE OF SECURITY BY OBSCURITY and Cloning MiFare Classic Rail and Building Passes, Anywhere, Anytime

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    , Anywhere, Anytime Nicolas T. Courtois University College London, Computer Science, Gower street, WC1E 6BT, London, UK Keywords: Access control, RFID, contactless smart cards, MiFare Classic, London Oyster card- wide and in public transportation. For more than 10 years the specification of these cards was kept

  4. A note on tsunami amplitudes above submarine slides and slumps M.I. Todorovska*, A. Hayir1

    E-Print Network [OSTI]

    Southern California, University of

    A note on tsunami amplitudes above submarine slides and slumps M.I. Todorovska*, A. Hayir1 , M 2531, Los Angeles, CA 90089-2531, USA Accepted 27 October 2001 Abstract Tsunami generated by submarine functions. Tsunami waveforms for these models are computed using linearized shallow water theory

  5. Structural and optical properties of GaAs-based heterostructures with Ge and Ge/InGaAs quantum wells

    SciTech Connect (OSTI)

    Aleshkin, V. Ya.; Dubinov, A. A., E-mail: sanya@ipm.sci-nnov.ru; Drozdov, M. N. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Zvonkov, B. N. [Nizhni Novgorod State University, Research Physical Technical Institute (Russian Federation); Kudryavtsev, K. E.; Tonkikh, A. A.; Yablonskiy, A. N. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Werner, P. [Max Planck Institute of Microstructure Physics (Germany)

    2013-05-15

    GaAs-based heterostructures with Ge and Ge/InGaAs quantum wells are grown by laser-assisted sputtering. Structural and optical studies of the heterostructures are carried out. A broad photoluminescence line is observed in the wavelength range from 1300 to 1650 nm. The line corresponds to indirect transitions in the momentum space of the Ge quantum wells and to transitions between the In{sub 0.28}Ga{sub 0.72}As and Ge layers, indirect in coordinate space, but direct in momentum space.

  6. Electrical spin injection using GaCrN in a GaN based spin light emitting diode

    SciTech Connect (OSTI)

    Banerjee, D.; Ganguly, S.; Saha, D.; Adari, R.; Sankaranarayan, S.; Kumar, A.; Aldhaheri, R. W.; Hussain, M. A.; Balamesh, A. S.

    2013-12-09

    We have demonstrated electrical spin-injection from GaCrN dilute magnetic semiconductor (DMS) in a GaN-based spin light emitting diode (spin-LED). The remanent in-plane magnetization of the thin-film semiconducting ferromagnet has been used for introducing the spin polarized electrons into the non-magnetic InGaN quantum well. The output circular polarization obtained from the spin-LED closely follows the normalized in-plane magnetization curve of the DMS. A saturation circular polarization of ?2.5% is obtained at 200?K.

  7. Effects of light illumination on electron velocity of AlGaN/GaN heterostructures under high electric field

    SciTech Connect (OSTI)

    Guo, Lei; Yang, Xuelin Cheng, Jianpeng; Sang, Ling; Xu, Fujun; Tang, Ning; Feng, Zhihong; Lv, Yuanjie; Wang, Xinqiang; Shen, B.; Ge, Weikun

    2014-12-15

    We have investigated the variation of electron velocity in AlGaN/GaN heterostructures depending on illuminating light intensity and wavelength. It is shown that the electron velocity at high electric field increases under above-band light illumination. This electron velocity enhancement is found to be related to the photo-generated cold holes which interact with hot electrons and thus accelerate the energy relaxation at high electric field. The results suggest an alternative way to improve the electron energy relaxation rate and hence the electron velocity in GaN based heterostructures.

  8. High-power InGaAs/GaAs quantum-well laser with enhanced broad spectrum of stimulated emission

    SciTech Connect (OSTI)

    Wang, Huolei; Yu, Hongyan; Zhou, Xuliang; Kan, Qiang; Yuan, Lijun; Wang, Wei; Pan, Jiaoqing, E-mail: jqpan@semi.ac.cn [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083 (China); Chen, Weixi [State Key Lab for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871 (China); Ding, Ying, E-mail: Ying.Ding@glasgow.ac.uk [School of Engineering, University of Glasgow, Glasgow G12 8LT (United Kingdom)

    2014-10-06

    We report the demonstration of an InGaAs/GaAs quantum well (QW) broadband stimulated emission laser with a structure that integrated a GaAs tunnel junction with two QW active regions. The laser exhibits ultrabroad lasing spectral coverage of ?51?nm at a center wavelength of 1060?nm with a total emission power of 790 mW, corresponding to a high average spectral power density of 15.5 mW/nm, under pulsed current conditions. Compared to traditional lasers, this laser with an asymmetric separate-confinement heterostructure shows broader lasing bandwidth and higher spectral power density.

  9. The PEANUT experiment in the NuMI beam at Fermilab

    SciTech Connect (OSTI)

    Russo, A. [Dipartimento di Scienze Fisiche, Universita Federico II di Napoli, 80125 Napoli (Italy)

    2010-03-30

    The PEANUT experiment was designed to study neutrino interactions in the few GeV range using the NuMI beam at Fermilab. The detector uses a hybrid technique, being made of nuclear emulsions and scintillator trackers. Emulsion films act as a tracking device and they are interleaved with lead plates used as neutrino targets. The detector is designed to reconstruct the topology of neutrino interactions at the single particle level. We present here the full reconstruction and analysis of a sample of 147 neutrino interactions that occurred in the PEANUT detector and the measurement of the quasielastic, resonance and deep-inelastic contributions to the total charged-current cross section. This technique could be applied for the beam monitoring at future neutrino facilities.

  10. Linear and nonlinear optical properties of GaAs/Al{sub x}Ga{sub 1?x}As/GaAs/Al{sub y}Ga{sub 1?y}As multi-shell spherical quantum dot

    SciTech Connect (OSTI)

    Emre Kavruk, Ahmet E-mail: aekavruk@gmail.com; Koc, Fatih; Sahin, Mehmet E-mail: mehsahin@gmail.com

    2013-11-14

    In this work, the optical properties of GaAs/Al{sub x}Ga{sub 1?x}As/GaAs/Al{sub y}Ga{sub 1?y}As multi-shell quantum dot heterostructure have been studied as a function of Al doping concentrations for cases with and without a hydrogenic donor atom. It has been observed that the absorption coefficient strength and/or resonant absorption wavelength can be adjusted by changing the Al content of inner-barrier and/or outer-barrier regions. Besides, it has been shown that the donor atom has an important effect on the control of the electronic and optical properties of the structure. The results have been presented as a function of the Al contents of the inner-barrier x and outer-barrier y regions and probable physical reasons have been discussed.

  11. Electrical degradation mechanisms of RF power GaAs PHEMTs

    E-Print Network [OSTI]

    Villanueva, Anita A. (Anita Ariel), 1978-

    2007-01-01

    GaAs Pseudomorphic High-Electron Mobility Transistors (PHEMTs) are widely used in RF power applications. Since these devices typically operate at high power levels and under high voltage biasing, their electrical reliability ...

  12. Evaporation-based Ge/.sup.68 Ga Separation

    DOE Patents [OSTI]

    Mirzadeh, Saed (Albuquerque, NM); Whipple, Richard E. (Los Alamos, NM); Grant, Patrick M. (Los Alamos, NM); O'Brien, Jr., Harold A. (Los Alamos, NM)

    1981-01-01

    Micro concentrations of .sup.68 Ga in secular equilibrium with .sup.68 Ge in strong aqueous HCl solution may readily be separated in ionic form from the .sup.68 Ge for biomedical use by evaporating the solution to dryness and then leaching the .sup.68 Ga from the container walls with dilute aqueous solutions of HCl or NaCl. The chloro-germanide produced during the evaporation may be quantitatively recovered to be used again as a source of .sup.68 Ga. If the solution is distilled to remove any oxidizing agents which may be present as impurities, the separation factor may easily exceed 10.sup.5. The separation is easily completed and the .sup.68 Ga made available in ionic form in 30 minutes or less.

  13. Validation of the MCNPX-PoliMi Code to Design a Fast-Neutron Multiplicity Counter

    SciTech Connect (OSTI)

    J. L. Dolan; A. C. Kaplan; M. Flaska; S. A. Pozzi; D. L. Chichester

    2012-07-01

    Many safeguards measurement systems used at nuclear facilities, both domestically and internationally, rely on He-3 detectors and well established mathematical equations to interpret coincidence and multiplicity-type measurements for verifying quantities of special nuclear material. Due to resource shortages alternatives to these existing He-3 based systems are being sought. Work is also underway to broaden the capabilities of these types of measurement systems in order to improve current multiplicity analysis techniques. As a part of a Material Protection, Accounting, and Control Technology (MPACT) project within the U.S. Department of Energy's Fuel Cycle Technology Program we are designing a fast-neutron multiplicity counter with organic liquid scintillators to quantify important quantities such as plutonium mass. We are also examining the potential benefits of using fast-neutron detectors for multiplicity analysis of advanced fuels in comparison with He-3 detectors and testing the performance of such designs. The designs are being developed and optimized using the MCNPX-PoliMi transport code to study detector response. In the full paper, we will discuss validation measurements used to justify the use of the MCNPX-PoliMi code paired with the MPPost multiplicity routine to design a fast neutron multiplicity counter with liquid scintillators. This multiplicity counter will be designed with the end goal of safeguarding advanced nuclear fuels. With improved timing qualities associated with liquid scintillation detectors, we can design a system that is less limited by nuclear materials of high activities. Initial testing of the designed system with nuclear fuels will take place at Idaho National Laboratory in a later stage of this collaboration.

  14. T-1025 IU SciBath-768 detector tests in MI-12

    SciTech Connect (OSTI)

    Tayloe, Rex; Cooper, R.; Garrison, L.; Thornton, T.; Rebenitsch, L.; DeJongh, Fritz; Loer, Benjamin; Ramberg, Erik; Yoo, Jonghee; /Fermilab

    2012-02-11

    This is a memorandum of understanding between the Fermi National Accelerator Laboratory (Fermilab) and the experimenters of Department of Physics and Center for Exploration of Energy and Matter, Indiana University, who have committed to participate in detector tests to be carried out during the 2012 Fermilab Neutrino program. The memorandum is intended solely for the purpose of recording expectations for budget estimates and work allocations for Fermilab, the funding agencies and the participating institutions. it reflects an arrangement that currently is satisfactory to the parties; however, it is recognized and anticipated that changing circumstances of the evolving research program will necessitate revisions. The parties agree to modify this memorandum to reflect such required adjustments. Actual contractual obligations will be set forth in separate documents. The experimenters propsoe to test their prototype 'SciBat-768' detector in the MI-12 building for 3 months (February-April) in Spring 2012. The major goal of this effort is to measure or limit the flux of beam-induced neutrons in a far-off-axis (> 45{sup o}) location of the Booster Neutrino Beamline (BNB). This flux is of interest for a proposed coherent neutral-current neutrino-argon elastic scattering experiment. A second goal is to collect more test data for the SciBath-768 to enable better understanding and calibration of the device. The SciBath-768 detector successfully ran for 3 months in the MINOS Underground Area in Fall 2011 as testbeam experiment T-1014 and is currently running above ground in the MINOS service building. For the run proposed here, the experiments are requesting: space in MI-12 in which to run the SciBath detector during February-April 2012 while the BNB is operating; technical support to help with moving the equipment on site; access to power, internet, and accelerator signals; and a small office space from which to run and monitor the experiment.

  15. Office of Student Financial Aid The Welcome Center 42 West Warren P.O. Box 2340 Detroit, MI 48202-0340 313-577-2100 Fax: 313-577-6648

    E-Print Network [OSTI]

    Finley Jr., Russell L.

    Office of Student Financial Aid The Welcome Center · 42 West Warren · P.O. Box 2340 · Detroit, MI. O. Box 2340 · 42 West Warren · Detroit, MI 48202-0340 2015-16 Verification of 2014 Income - Student · Detroit, MI 48202-0340 · 313-577-2100 · Fax: 313-577-6648 studentservice@wayne.edu · wayne

  16. Low temperature carrier redistribution dynamics in InGaN/GaN quantum wells

    SciTech Connect (OSTI)

    Badcock, T. J., E-mail: Thomas.badcock@crl.toshiba.co.uk; Dawson, P.; Davies, M. J. [School of Physics and Astronomy, Photon Science Institute, Alan Turing Building, University of Manchester, Manchester M13 9PL (United Kingdom); Kappers, M. J.; Massabuau, F. C.-P.; Oehler, F.; Oliver, R. A.; Humphreys, C. J. [Department of Materials Science and Metallurgy, 27 Charles Babbage Road, University of Cambridge, Cambridge CB3 0FS (United Kingdom)

    2014-03-21

    We have studied the carrier recombination dynamics in an InGaN/GaN multiple quantum well structure as a function of emission energy and excitation density between temperatures of 10?K and 100?K. Under relatively low levels of excitation, the photoluminescence (PL) intensity and decay time of emission on the high energy side of the luminescence spectrum decrease strongly between 10?K and 50?K. In contrast, for emission detected on the low energy side of the spectrum, the PL intensity and decay time increase over the same temperature range. These results are consistent with a thermally activated carrier redistribution process in which the (temperature dependent) average timescale for carrier transfer into or out of a localised state depends on the energy of the given state. Thus, the transfer time out of shallow, weakly localised states is considerably shorter than the arrival time into more deeply localised states. This picture is consistent with carriers hopping between localisation sites in an uncorrelated disorder potential where the density of localised states decreases with increasing localisation depth, e.g., a exponential or Gaussian distribution resulting from random alloy disorder. Under significantly higher levels of excitation, the increased occupation fraction of the localised states results in a greater average separation distance between unoccupied localised states, causing a suppression of the spectral and dynamic signatures of the hopping transfer of carriers.

  17. PHYSICAL REVIEW B 83, 165407 (2011) Two-dimensional Mn structure on the GaN growth surface and evidence for room-temperature

    E-Print Network [OSTI]

    2011-01-01

    Nanotecnolog´ia, Universidad Nacional Aut´onoma de M´exico, Apartado Postal 14, Ensenada Baja California

  18. Super-Eddington wind scenario for the progenitors of type Ia supernovae: Accreting He-rich matter onto white dwarfs

    E-Print Network [OSTI]

    Wang, Bo; Ma, Xin; Liu, Dongdong; Cui, Xiao; Han, Zhanwen

    2015-01-01

    Supernovae of type Ia (SNe Ia) are believed to be thermonuclear explosions of carbon-oxygen white dwarfs (CO WDs). However, the mass accretion process onto CO WDs is still not completely understood. In this paper, we study the accretion of He-rich matter onto CO WDs and explore a scenario in which a strong wind forms on the surface of the WD if the total luminosity exceeds the Eddington limit. Using a stellar evolution code called modules for experiments in stellar astrophysics (MESA), we simulated the He accretion process onto CO WDs for WDs with masses of 0.6-1.35Msun and various accretion rates of 10^{-8}-10^{-5}Msun/yr. If the contribution of the total luminosity is included when determining the Eddington accretion rate, then a super-Eddington wind could be triggered at relatively lower accretion rates than those of previous studies based on steady-state models. The super-Eddington wind can prevent the WDs with high accretion rates from evolving into red-giant-like He stars. We found that the contribution...

  19. Green (In,Ga,Al)P-GaP light-emitting diodes grown on high-index GaAs surfaces

    SciTech Connect (OSTI)

    Ledentsov, N. N., E-mail: nikolay.ledentsov@v-i-systems.com; Shchukin, V. A. [VI Systems GmbH, Hardenbergstr. 7, Berlin D-10623 (Germany); Lyytikäinen, J.; Okhotnikov, O. [Optoelectronics Research Centre, Tampere University of Technology, Tampere FI-33720 (Finland); Shernyakov, Yu. M.; Payusov, A. S.; Gordeev, N. Yu.; Maximov, M. V. [A. F. Ioffe Physical Technical Institute of the Russian Academy of Sciences, Politekhnicheskaya 26, St. Petersburg 194021 (Russian Federation); Schlichting, S.; Nippert, F.; Hoffmann, A. [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, Berlin D-10623 (Germany)

    2014-11-03

    We report on green (550–560?nm) electroluminescence (EL) from (Al{sub 0.5}Ga{sub 0.5}){sub 0.5}In{sub 0.5}P-(Al{sub 0.8}Ga{sub 0.2}){sub 0.5}In{sub 0.5}P double p-i-n heterostructures with monolayer-scale GaP insertions in the cladding layers and light-emitting diodes based thereupon. The structures are grown side-by-side on high-index and (100) GaAs substrates by molecular beam epitaxy. At moderate current densities (?500?A/cm{sup 2}), the EL intensity of the structures is comparable for all substrate orientations. Opposite to the (100)-grown strictures, the EL spectra of (211) and (311)-grown devices are shifted towards shorter wavelengths (?550?nm at room temperature). At high current densities (>1?kA/cm{sup 2}), a much higher EL intensity is achieved for the devices grown on high-index substrates. The integrated intensity of (311)-grown structures gradually saturates at current densities above 4?kA/cm{sup 2}, whereas no saturation is revealed for (211)-grown structures up to the current densities above 14?kA/cm{sup 2}. We attribute the effect to the surface orientation-dependent engineering of the GaP band structure, which prevents the escape of the nonequilibrium electrons into the indirect conduction band minima of the p-doped (Al{sub 0.8}Ga{sub 0.2}){sub 0.5}In{sub 0.5}P cladding layers.

  20. Influence of stress on optical transitions in GaN nanorods containing a single InGaN/GaN quantum disk

    SciTech Connect (OSTI)

    Zhuang, Y. D.; Shields, P. A.; Allsopp, D. W. E., E-mail: d.allsopp@bath.ac.uk [Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY (United Kingdom); Bruckbauer, J.; Edwards, P. R.; Martin, R. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2014-11-07

    Cathodoluminescence (CL) hyperspectral imaging has been performed on GaN nanorods containing a single InGaN quantum disk (SQD) with controlled variations in excitation conditions. Two different nanorod diameters (200 and 280?nm) have been considered. Systematic changes in the CL spectra from the SQD were observed as the accelerating voltage of the electron beam and its position of incidence are varied. It is shown that the dominant optical transition in the SQD varies across the nanorod as a result of interplay between the contributions of the deformation potential and the quantum-confined Stark effect to the transition energy as consequence of radial variation in the pseudomorphic strain.

  1. Inland EmpIrE mErchandIsE Exports calIfornIa statE UnIvErsIty fUllErton

    E-Print Network [OSTI]

    de Lijser, Peter

    Inland EmpIrE mErchandIsE Exports calIfornIa statE UnIvErsIty fUllErton 20122012 CSUF Mihaylo University, Fullerton An Overview and Analysis of Inland Empire Exports #12;novEmbEr 2011 InstItUtE for EconomIc and EnvIronmEntal stUdIEs33 #12;Inland EmpIrE mErchandIsE Exports calIfornIa statE UnIvErsIty f

  2. High intensity low temperature (HILT) performance of space concentrator GaInP/GaInAs/Ge MJ SCs

    SciTech Connect (OSTI)

    Shvarts, Maxim Z., E-mail: shvarts@scell.ioffe.ru; Kalyuzhnyy, Nikolay A.; Mintairov, Sergey A.; Soluyanov, Andrei A.; Timoshina, Nailya Kh. [Ioffe Physical-Technical Institute, 26 Polytekhnicheskaya str., St.-Petersburg, 194021 (Russian Federation); Gudovskikh, Alexander S. [Saint-Petersburg Academic University - Nanotechnology Research and Education Centre RAS, St. Petersburg, 194021 (Russian Federation); Luque, Antonio [Ioffe Physical-Technical Institute, 26 Polytekhnicheskaya str., St.-Petersburg, 194021, Russia and Instituto de Energia Solar, Universidad Politecnica de Madrid, Madrid (Spain)

    2014-09-26

    In the work, the results of an investigation of GaInP/GaInAs/Ge MJ SCs intended for converting concentrated solar radiation, when operating at low temperatures (down to ?190 °C) are presented. A kink of the cell I-V characteristic has been observed in the region close to V{sub oc} starting from ?20°C at operation under concentrated sunlight. The causes for its occurrence have been analyzed and the reasons for formation of a built-in potential barrier for majority charge carriers at the n-GaInP/n-Ge isotype hetero-interface are discussed. The effect of charge carrier transport in n-GaInP/n-pGe heterostructures on MJ SC output characteristics at low temperatures has been studied including EL technique.

  3. The origin and reduction of switching noise in GaAs/AlGaAs lateral gated devices

    E-Print Network [OSTI]

    Davies, John H.

    to cryogenic temperature with all gates grounded to the substrate to protect against electrostatic effects in AlGaAs: electrons `freeze' into deep traps ­ DX centres ­ below about 150 K. The occupation of donors

  4. Design and fabrication of InGaN/GaN heterojunction bipolar transistors for microwave power amplifiers

    E-Print Network [OSTI]

    Keogh, David Martin

    2006-01-01

    assuming the material growth technology allows for all ofand a relatively immature growth technology, as well as theof the art for InGaN growth technology. Epitaxial growth of

  5. Polarization field engineering of GaN/AlN/AlGaN superlattices for enhanced thermoelectric properties

    SciTech Connect (OSTI)

    Sztein, Alexander, E-mail: asztein@umail.ucsb.edu [Materials Department, University of California, Santa Barbara, California 93106 (United States); Bowers, John E.; DenBaars, Steven P.; Nakamura, Shuji [Materials Department, University of California, Santa Barbara, California 93106 (United States); Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106 (United States)

    2014-01-27

    A novel polarization field engineering based strategy to simultaneously achieve high electrical conductivity and low thermal conductivity in thermoelectric materials is demonstrated. Polarization based electric fields are used to confine electrons into two-dimensional electron gases in GaN/AlN/Al{sub 0.2}Ga{sub 0.8}N superlattices, resulting in improved electron mobilities as high as 1176 cm{sup 2}/Vs and in-plane thermal conductivity as low as 8.9?W/mK. The resulting room temperature ZT values reach 0.08, a factor of four higher than InGaN and twelve higher than GaN, demonstrating the potential benefits of this polarization based engineering strategy for improving the ZT and efficiencies of thermoelectric materials.

  6. Si-CMOS-Like Integration of AlGaN/GaN Dielectric-Gated High-Electron-Mobility Transistors 

    E-Print Network [OSTI]

    Johnson, Derek Wade

    2014-07-31

    production is projected to consume ~100,000 wafers per year by 2015 (Yole Development, “Power GaN – 2012 Edition”), this manufacturing breakthrough represents potential savings of ~$17 million per year....

  7. Characterization of the gate oxide of an AlGaN/GaN high electron mobility transistor

    E-Print Network [OSTI]

    Florida, University of

    2011; published online 21 March 2011 A subnanometer thick interfacial oxide layer present between used to characterize a Ni/AlGaN interfacial oxide layer with subnanometer thickness. The semiconducting

  8. The first principle study of Ni{sub 2}ScGa and Ni{sub 2}TiGa

    SciTech Connect (OSTI)

    Özduran, Mustafa; Turgut, Kemal; Arikan, Nihat; ?yigör, Ahmet; Candan, Abdullah

    2014-10-06

    We computed the electronic structure, elastic moduli, vibrational properties, and Ni{sub 2}TiGa and Ni{sub 2}ScGa alloys in the cubic L2{sub 1} structure. The obtained equilibrium lattice constants of these alloys are in good agreement with available data. In cubic systems, there are three independent elastic constants, namely C{sub 11}, C{sub 12} and C{sub 44}. We calculated elastic constants in L2{sub 1} structure for Ni{sub 2}TiGa and Ni{sub 2}ScGa using the energy-strain method. The electronic band structure, total and partial density of states for these alloys were investigated within density functional theory using the plane-wave pseudopotential method implemented in Quantum-Espresso program package. From band structure, total and projected density of states, we observed metallic characters of these compounds. The electronic calculation indicate that the predominant contributions of the density of states at Fermi level come from the Ni 3d states and Sc 3d states for Ni{sub 2}TiGa, Ni 3d states and Sc 3d states for Ni{sub 2}ScGa. The computed density of states at Fermi energy are 2.22 states/eV Cell for Ni{sub 2}TiGa, 0.76 states/eV Cell for Ni{sub 2}ScGa. The vibrational properties were obtained using a linear response in the framework at the density functional perturbation theory. For the alloys, the results show that the L2{sub 1} phase is unstable since the phonon calculations have imagine modes.

  9. Optical investigation of InAs quantum dots inserted in AlGaAs/GaAs modulation doped heterostructure

    SciTech Connect (OSTI)

    Khmissi, H.; Baira, M.; Bouzaieene, L.; Saidi, F.; Maaref, H. [Laboratoire de Micro-optoelectronique et Nanostructures, Universite de Monastir (Tunisia); Sfaxi, L. [Laboratoire de Micro-optoelectronique et Nanostructures, Universite de Monastir (Tunisia); Universite de Sousse Faculte des Sciences de Monastir, Avenue de l'Environnement 5019 Monastir (Tunisia); Bru-Chevallier, C. [Institut des Nanotechnologies de Lyon (INL), CNRS UMR-5270, INSA-LYON, 7, Avenue Jean Capelle, Bat. Blaise Pascal, 69621 Villeurbanne (France)

    2011-03-01

    Optical properties of InAs quantum dots (QDs) inserted in AlGaAs/GaAs modulation doped heterostructure are investigated. To study the effect of carrier transfer behavior on the luminescence of self-assembled quantum dots, a series of sample has been prepared using molecular beam epitaxy (Riber 32 system) in which we have varied the thickness separating the delta dopage and the InAs quantum dots layer. Photoluminescence spectra show the existence of two peaks that can be attributed to transition energies from the ground state (E{sub 1}-HH{sub 1}) and the first excited state (E{sub 2}-HH{sub 2}). Two antagonist effects have been observed, a blue shift of the emission energies result from electron transferred from the AlGaAs/GaAs heterojunction to the InAs quantum dots and a red shift caused by the quantum confined Stark effect due to the internal electric field existing In the AlGaAs/GaAs heterojunction.

  10. Effects of high-temperature AIN buffer on the microstructure of AlGaN/GaN HEMTs

    SciTech Connect (OSTI)

    Coerekci, S.; Oeztuerk, M. K.; Yu, Hongbo; Cakmak, M.; Oezcelik, S.; Oezbay, E.

    2013-06-15

    Effects on AlGaN/GaN high-electron-mobility transistor structure of a high-temperature AlN buffer on sapphire substrate have been studied by high-resolution x-ray diffraction and atomic force microscopy techniques. The buffer improves the microstructural quality of GaN epilayer and reduces approximately one order of magnitude the edge-type threading dislocation density. As expected, the buffer also leads an atomically flat surface with a low root-mean-square of 0.25 nm and a step termination density in the range of 10{sup 8} cm{sup -2}. Due to the high-temperature buffer layer, no change on the strain character of the GaN and AlGaN epitaxial layers has been observed. Both epilayers exhibit compressive strain in parallel to the growth direction and tensile strain in perpendicular to the growth direction. However, an high-temperature AlN buffer layer on sapphire substrate in the HEMT structure reduces the tensile stress in the AlGaN layer.

  11. p-doping-free InGaN/GaN light-emitting diode driven by three-dimensional hole gas

    SciTech Connect (OSTI)

    Zhang, Zi-Hui; Tiam Tan, Swee; Kyaw, Zabu; Liu, Wei; Ji, Yun; Ju, Zhengang; Zhang, Xueliang [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore) [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Wei Sun, Xiao, E-mail: EXWSUN@ntu.edu.sg [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Department of Electronics and Electrical Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Volkan Demir, Hilmi, E-mail: VOLKAN@stanfordalumni.org [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Department of Electrical and Electronics, UNAM-Institute of Material Science and Nanotechnology, Bilkent University, Ankara TR-06800 (Turkey); Department of Physics, UNAM-Institute of Material Science and Nanotechnology, Bilkent University, Ankara TR-06800 (Turkey)

    2013-12-23

    Here, GaN/Al{sub x}Ga{sub 1-x}N heterostructures with a graded AlN composition, completely lacking external p-doping, are designed and grown using metal-organic-chemical-vapour deposition (MOCVD) system to realize three-dimensional hole gas (3DHG). The existence of the 3DHG is confirmed by capacitance-voltage measurements. Based on this design, a p-doping-free InGaN/GaN light-emitting diode (LED) driven by the 3DHG is proposed and grown using MOCVD. The electroluminescence, which is attributed to the radiative recombination of injected electrons and holes in InGaN/GaN quantum wells, is observed from the fabricated p-doping-free devices. These results suggest that the 3DHG can be an alternative hole source for InGaN/GaN LEDs besides common Mg dopants.

  12. Lasing characteristics of GaSb/GaAs self-assembled quantum dots embedded in an InGaAs quantum well

    E-Print Network [OSTI]

    Jalali. Bahram

    Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico, New Mexico 87545 Received 26 February 2007; accepted 1 June 2007; published online 28 June 2007 intriguing optoelectronic device possibilities on GaAs substrates including lasers, detectors, or solar cells

  13. A 3-10 GHZLCR-matched Power Amplifier using Flip-Chip Mounted AlGaN/GaN HEMTs

    E-Print Network [OSTI]

    York, Robert A.

    amplifier using GaN- HEMTs-on-Sapphire. I INTRODUCTION GaN HEMTs have enormous potential for realizing high-power Traveling Wave Power Amplifier circuit (TWPA)[1][2] for realization of wideband power amplifiersWE4A-5 A 3-10 GHZLCR-matched Power Amplifier using Flip-Chip Mounted AlGaN/GaN HEMTs Jane J

  14. Intermixing of InGaAs/GaAs Quantum Well Using Multiple Cycles Annealing Cu-doped SiO2

    SciTech Connect (OSTI)

    Hongpinyo, V; Ding, Y H; Dimas, C E; Wang, Y; Ooi, B S; Qiu, W; Goddard, L L; Behymer, E M; Cole, G D; Bond, T C

    2008-06-11

    The authors investigate the effect of intermixing in InGaAs/GaAs quantum well structure using Cu-doped SiO{sub 2}. The incorporation of Cu into the silica film yields larger bandgap shift than typical impurity-free vacancy diffusion (IFVD) method at a lower activation temperature. We also observe enhancement of the photoluminescence (PL) signal from the intermixed InGaAs/GaAs quantum well structure after being cycle-annealed at 850 C.

  15. Metamorphic GaAsP buffers for growth of wide-bandgap InGaP solar cells J. Simon,1,a

    E-Print Network [OSTI]

    Haller, Gary L.

    . INTRODUCTION Triple-junction metamorphic solar cells have reached ef- ficiencies as high as 41.1% by combiningMetamorphic GaAsP buffers for growth of wide-bandgap InGaP solar cells J. Simon,1,a S. Tomasulo,1 P-yP solar cells. Tensile-strained GaAsxP1-x buffers grown on GaAs using unoptimized conditions

  16. FIRST DEMONSTRATION OF MONOLITHIC InP-BASED InAlAs/InGaAsP/InGaAs TRIPLE JUNCTION SOLAR CELLS

    E-Print Network [OSTI]

    Atwater, Harry

    FIRST DEMONSTRATION OF MONOLITHIC InP-BASED InAlAs/InGaAsP/InGaAs TRIPLE JUNCTION SOLAR CELLS RobynAlAs/InGaAsP/InGaAs triple junction solar cell grown on InP substrate. X-ray diffraction characterization shows high quality solar cell materials. Preliminary 1-sun AM1.5D testing of the triple junction solar cell shows promising

  17. Characterization of Cu(In,Ga)Se2 (CIGS) films with varying gallium ratios

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Claypoole, Jesse; Peace, Bernadette; Sun, Neville; Dwyer, Dan; Eisaman, Matthew D.; Haldar, Pradeep; Efstathiadis, Harry

    2015-09-05

    Cu(In1-x,Gax)Se2 (CIGS) absorber layers were deposited on molybdenum (Mo) coated soda-lime glass substrates with varying Ga content (described as Ga/(In+Ga) ratios) with respect to depth. As the responsible mechanisms for the limitation of the performance of the CIGS solar cells with high Ga contents are not well understood, the goal of this work was to investigate different properties of CIGS absorber films with Ga/(In+Ga) ratios varied between 0.29 and 0.41 (as determined by X-ray florescence spectroscopy (XRF)) in order to better understand the role that the Ga content has on film quality. The Ga grading in the CIGS layer hasmore »the effect causing a higher bandgap toward the surface and Mo contact while the band gap in the middle of the CIGS layer is lower. Also, a wider and larger Ga/(In+Ga) grading dip located deeper in the CIGS absorber layers tend to produce larger grains in the regions of the films that have lower Ga/(In+Ga) ratios. It was found that surface roughness decreases from 51.2 nm to 41.0 nm with increasing Ga/(In+Ga) ratios. However, the surface roughness generally decreases if the Ga grading occurs deeper in the absorber layer.« less

  18. Radiation damage of GaAs thin-film solar cells on Si substrates

    SciTech Connect (OSTI)

    Itoh, Y.; Yamaguchi, M.; Nishioka, T.; Yamamoto, A.

    1987-01-15

    1-MeV electron irradiation damages in GaAs thin-film solar cells on Si substrates are examined for the first time. Damage constant for minority-carrier diffusion length in GaAs heteroepitaxial films on Si substrates is found to be the same as that in GaAs homoepitaxial films on GaAs substrates. This agreement suggests that GaAs/Si has the same defect introduction rate with radiation as GaAs/GaAs. The degradation of GaAs solar cells on Si with electron irradiation is less than that of GaAs solar cells on GaAs, because in the present, GaAs films on Si substrates have lower minority-carrier diffusion length compared to GaAs films on GaAs and these films are insensitive to radiation. The p/sup +/-p/sup +/-n AlGaAs-GaAs heteroface solar cell with junction depth of about 0.3 ..mu..m is concluded to be useful for a high-efficiency and radiation-resistant solar cell fabricated on a Si substrate.

  19. Laser Gain and Threshold Properties in Compressive-Strained and Lattice-Matched GaInNAs/GaAs Quantum Wells

    SciTech Connect (OSTI)

    Chow, W.W.; Jones, E.D.; Modine, N.A.; Allerman, A.A.; Kurtz, S.R.

    1999-08-04

    The optical gain spectra for compressive-strained and lattice-matched GaInNAs/GaAs quantum wells are computed using a microscopic laser theory. From these spectra, the peak gain and carrier radiative decay rate as functions of carrier density are determined. These dependences allow the study of lasing threshold current density for different GAInNAs/GaAs laser structures.

  20. Published in 2009 by John Wiley & Sons, Ltd Correspondence to: David A. Laird, USDA, ARS, National Soil Tilth Laboratory, 2110 University Blvd., Ames IA 50011-3120, USA.

    E-Print Network [OSTI]

    Lehmann, Johannes

    of the pyrolysis platform for coproducing bio-oil and biochar David A. Laird, USDA-ARS-National Soil Tilth Soil Tilth Laboratory, 2110 University Blvd., Ames IA 50011-3120, USA. E-mail: david:547­562 (2009) Abstract: Pyrolysis is a relatively simple, inexpensive, and robust thermochemical technology