Sample records for antiknock in dex

  1. Handling uncertainty in DEX methodology Martin Znidarsic

    E-Print Network [OSTI]

    Bohanec, Marko

    URPDM2010 1 Handling uncertainty in DEX methodology Martin Znidarsic Jozef Stefan Institute, Jamova cesta 39, Marko Bohanec Jozef Stefan Institute, Jamova cesta 39, marko

  2. E-Print Network 3.0 - antiknock ratings Sample Search Results

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

    Environmental Sciences and Ecology ; Geosciences 20 PROPERTIES, IDENTIFICATION, HEAT TREATMENT OF METALS Summary: (paint pigment) and tetraethyl lead (antiknock...


    SciTech Connect (OSTI)

    Mann, Andrew W.; Hilton, Eric J. [Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Dr, Honolulu, HI 96822 (United States); Brewer, John M. [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Gaidos, Eric [Department of Geology and Geophysics, University of Hawai'i, 1680 East-West Road, Honolulu, HI 96822 (United States); Lepine, Sebastien [Department of Astrophysics, American Museum of Natural History, New York, NY 10024 (United States)


    Knowledge of late K and M dwarf metallicities can be used to guide planet searches and constrain planet formation models. However, the determination of metallicities of late-type stars is difficult because visible wavelength spectra of their cool atmospheres contain many overlapping absorption lines, preventing the measurement of equivalent widths. We present new methods, and improved calibrations of existing methods, to determine metallicities of late K and M dwarfs from moderate resolution (1300 < R < 2000) visible and infrared spectra. We select a sample of 112 wide binary systems that contain a late-type companion to a solar-type primary star. Our sample includes 62 primary stars with previously published metallicities, as well as 50 stars with metallicities determined from our own observations. We use our sample to empirically determine which features in the spectrum of the companion are best correlated with the metallicity of the primary. We find {approx_equal}120 features in K and M dwarf spectra that are useful for predicting metallicity. We derive metallicity calibrations for different wavelength ranges, and show that it is possible to get metallicities reliable to <0.10 dex using either visible, J-, H-, or K-band spectra. We find that the most accurate metallicities derived from visible spectra requires the use of different calibrations for early-type (K5.5-M2) and late-type (M2-M6) dwarfs. Our calibrations are applicable to dwarfs with metallicities of -1.04 < [Fe/H] <+0.56 and spectral types from K7 to M5. Lastly, we use our sample of wide binaries to test and refine existing calibrations to determine M dwarf metallicities. We find that the {zeta} parameter, which measures the ratio of TiO can CaH bands, is correlated with [Fe/H] for super-solar metallicities, and {zeta} does not always correctly identify metal-poor M dwarfs. We also find that existing calibrations in the K and H bands are quite reliable for stars with [Fe/H] >-0.5, but are less useful for more metal-poor stars.

  4. Lead contamination in street soils of Nairobi City and Mombasa Island, Kenya

    SciTech Connect (OSTI)

    Onyari, J.M.; Wandiga, S.O.; Njenga, G.K.; Nyatebe, J.O. (Univ. of Nairobi (Kenya))


    The advent of modern industrialization and, in particular, the motor vehicle has witnessed dramatic increases in lead usage both as a component of lead-acid storage battery and from 1923 as organic lead alkyl anti-knock additive in petroleum. Several workers have established a correlation between increasing lead concentration in roadside soils and vehicular traffic density. Although researchers studied the heavy metal content in Lake Victoria sediments, no urban roadside soils were investigated. Since lead is used as a petrol additive in Kenya, it is necessary to document the extent and magnitude of lead contamination of roadside soils in inland and coastal urban environments and evaluate its environmental implications.


    E-Print Network [OSTI]

    Kannan, Ram


    antagonizes the second step of splicing in the context of TER1 suggests that the BS-U2 snRNA interactions are disrupted after the first step and thus earlier than previously thought. The slow transition from first to second step triggers the Prp22 DEx...

  6. Authors, Titles, Subjects in the Marine Fisheries Review,

    E-Print Network [OSTI]

    , news articles, and regular departments are not in- dexed. A "Adult coho salmon recoveries and their Na., "Economic analysis of 'steam-shock' and 'pasteurization' pro- cesses for oyster shucking," 5:21 Buckley and gear, 8:3 Virginia, 8: I0 worldwide and United States, 8: II Clam surveys design of electrohydraulic

  7. Motor gasolines, winter 1981-1982

    SciTech Connect (OSTI)

    Shelton, E M


    Analytical data for 905 samples of motor gasoline, were collected from service stations throughout the country and were analyzed in the laboratories of various refiners, motor manufacturers, and chemical companies. The data were submitted to the Bartlesville Energy Technology Center for study, necessary calculations, and compilation under a cooperative agreement between the Bartlesville Energy Technology Center (BETC) and the American Petroleum Institute (API). The samples represent the products of 30 companies, large and small, which manufacture and supply gasoline. These data are tabulated by groups according to brands (unlabeled) and grades for 17 marketing districts into which the country is divided. A map included in this report, shows marketing areas, districts and sampling locations. The report also includes charts indicating the trends of selected properties of motor fuels since winter 1959-1960 survey for the leaded gasolines, and since winter 1979-1980 survey for the unleaded gasolines. Sixteen octane distribution percent charts for areas 1, 2, 3, and 4 for unleaded antiknock index (R+M)/2 below 90.0, unleaded antiknock index (R+M)/2 90.0 and above, leaded antiknock index (R+M)/2 below 93.0, and leaded antiknock index (R+M)/2 93.0 and above grades of gasoline are presented in this report. The antiknock (octane) index (R+M)/2 averages of gasoline sold in this country were 87.4 for unleaded below 90.0, 91.7 for unleaded 90.0 and above, and 88.9 for leaded below 93.0. Only one sample was reported as 93.0 for leaded gasolines with an antiknock index (R+M)/2 93.0 and above.

  8. Anne Le Mouel, paper ID# 4-054-12 Fostering Energy Efficiency in manufacturing plants

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    economical breakthroughs in power and flow rate measurement Anne Le Mouel, EDF R&D Eco-Efficiency Cédex, FRANCE Email: Gilbert Schmitt, EDF R&D Eco-Efficiency & Industrial Process: Maxime Dupont, EDF R&D Eco-Efficiency & Industrial Process Department Site des

  9. Abundances of Vanadium and Bromine in 3 Cen A: Additional Odd-Z Anomalies

    E-Print Network [OSTI]

    C. R. Cowley; G. M. Wahlgren


    We report abundance excesses of 1.2 and 2.6 dex, respectively, for vanadium and bromine in the hot, peculiar star 3 Cen A. Abundances for these two odd-Z elements have not been previously reported for this star. Taken with previous work, they strengthen the case of the origin of the abundance peculiarities by diffusion.

  10. Informatica 37 (2013) 49-54 49 DEX Methodology: Three Decades of Qualitative Multi-Attribute

    E-Print Network [OSTI]

    Bohanec, Marko


    -Attribute Modeling Marko Bohanec and Martin Znidarsic Jozef Stefan Institute, Department of Knowledge Technologies


    E-Print Network [OSTI]

    Bohanec, Marko

    , Vladislav Rajkovic2 , Ivan Bratko3 , Blaz Zupan3 , Martin Znidarsic1 1 Institut Jozef Stefan, Odsek za

  12. CONTRACTNO.: DE-X13-96GJ87335 TASK ORDER NO.: h

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling7111A Lithologic andRECORD OF DECISION:L^_. .

  13. NERSC CoDEx Project: A Hardware/Software Codesign Environment for the

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)Integrated Codes |IsLove Your1Allocations NERSC Allocations:Carver HoursExascale

  14. Study Humanities and Social Science Abroad General/Most All

    E-Print Network [OSTI]

    Maxwell, Bruce D.

    ) American University of Rome in Rome (CCIS) Japan- Kumamoto University (DEX)* Malta - University of Malta

  15. The oxygen abundance distribution in M101

    E-Print Network [OSTI]

    L. S. Pilyugin


    The well-observed spiral galaxy M101 was considered. The radial distributions of oxygen abundances determined in three different ways (with the classic Te - method, with the R23 - method, and with the P -- method) were compared. It was found that the parameters (the central oxygen abundance and the gradient) of the radial O/H(P) abundance distribution are close to those of the O/H(Te) abundance distribution. The parameters of the O/H(R23) abundance distribution differ significantly from those of the O/H(Te) abundance distribution: the central O/H(R23) oxygen abundance is higher by around 0.4dex and the gradient is steeper by a factor of around 1.5 as compared to those values in the O/H(Te) abundance distribution. The dispersion in O/H(P) abundance at fixed radius is rather small, around 0.08 dex, and is equal to that in O/H(Te) abundance. The dispersion in O/H(R23) abundance at fixed radius is appreciably larger, around 0.16 dex, compared to that in O/H(Te) abundance. It has been shown that the extra dispersion in O/H(R23) abundances is an artifact and reflects scatter in excitation parameter P at fixed radius.

  16. Chemo-spectrophotometric evolution of spiral galaxies: III. Abundance and colour gradients in discs

    E-Print Network [OSTI]

    N. Prantzos; S. Boissier


    We study the relations between luminosity and chemical abundance profiles of spiral galaxies, using detailed models for the chemical and spectro-photometric evolution of galactic discs. The models are ``calibrated'' on the Milky Way disc and are successfully extended to other discs with the help of simple ``scaling'' relations, obtained in the framework of semi-analytic models of galaxy formation. We find that our models exhibit oxygen abundance gradients that increase in absolute value with decreasing disc luminosity (when expressed in dex/kpc) and are independent of disc luminosity (when expressed in dex/scalelength), both in agreement with observations. We notice an important strong correlation between abundance gradient and disc scalelength. These results support the idea of ``homologuous evolution'' of galactic discs.

  17. Nonspecific excitatory effects of opiates and their possible role in withdrawal behavior

    E-Print Network [OSTI]

    Stevens, David Ronald


    in 1971 and have since then carried out a number of studies of precipi- tated withdrawal. In these studies, either multiple injections or pellet implantation was used to induce dependence (3), In 1971, Cheney and Goldstein demonstrated that withdrawal... of the opiate antagonist naloxone (NAL) exhib1ted significant with- drawal-11ke behavior following opiate injection, suggesting a non- opiate receptor medi ated action for these behavioral signs . Dextror- phan (DEX) treatment in combination with NAL also...

  18. On the lithium dip in the metal poor open cluster NGC 2243

    SciTech Connect (OSTI)

    Franois, P. [GEPI, Paris-Meudon Observatory, 61 Avenue de l'Observatoire, F-75014 Paris (France); Pasquini, L.; Palsa, R. [ESO, European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei Mnchen (Germany); Biazzo, K. [INAF, Capodimonte Astronomical Observatory, via Moiariello 16, 80131 Naples (Italy); Bonifacio, P. [GEPI, Paris-Meudon Observatory, Place Jules Janssen 92190, Meudon (France)


    Lithium is a key element for studying the mixing mechanisms operating in stellar interiors. It can also be used to probe the chemical evolution of the Galaxy and the Big Bang nucleosynthesis. Measuring the abundance of Lithium in stars belonging to Open Clusters (hereafter OC) allows a detailed comparison with stellar evolutionary models. NGC 2243 is particularly interesting thanks to its relative low metallicity ([Fe/H]=?0.54 0.10 dex). We performed a detailed analysis of high-resolution spectra obtained with the multi-object facility FLAMES at the VLT 8.2m telescope. Lithium abundance has been measured in 27 stars. We found a Li dip center of 1.06 M{sub ?}, which is significantly smaller than that observed in solar metallicity and metal-rich clusters. This finding confirms and strengthens the conclusion that the mass of the stars in the Li dip strongly depends on stellar metallicity. The mean Li abundance of the cluster is log n(Li) = 2.70 dex, which is substantially higher than that observed in 47 Tue. We derived an iron abundance of [Fe/H]=?0.540.10 dex for NGC 2243, in agreement (within the errors) with previous findings.

  19. The Role of Angiopoietin-like 4 in Lipid Homeostasis

    E-Print Network [OSTI]

    Gray, Nora


    DEX: dexamethasone DEXA: dual energy X-ray absorptiometryand scanned by dual-energy X-ray absorptiometry (DEXA) with

  20. Localization lengths for Schroedinger operators on Z^2 with decaying random potentials

    E-Print Network [OSTI]

    Thomas Chen


    We study a class of Schr\\"odinger operators on $\\Z^2$ with a random potential decaying as $|x|^{-\\dex}$, $00$. These estimates "interpolate" between the lower bound $\\lambda^{-2+\\eta}$ due to recent work of Schlag-Shubin-Wolff for $\\dex=0$, and pure a.c. spectrum for $\\dex>\\frac12$ demonstrated in recent work of Bourgain.

  1. In vitro and in vivo activation of the pituitary-adrenal axis by corticotropin-releasing factor, vasopressin (VP), and two VP analogs

    E-Print Network [OSTI]

    Carroll, Jeffery Allen


    's objectives were to: 1) compare the relative potency of a VP analog with that of CRF and VP in terms of ACTH secretion by cultured bovine corticotrophs; 2) evaluate a VP analog as an antagonist of VP-induced ACTH secretion by cultured bovine corticotrophs...; 3) evaluate the ability of CRF and VP to induce ACTH secretion in vivo in cattle; and, 4) evaluate the ability of the antiglucocorticoid, RU486, to block the inhibitory effects of dexamethasone (DEX) on CRF- and VP-induced ACTH secretion in vitro...


    SciTech Connect (OSTI)

    Cohen, Judith G., E-mail: [Palomar Observatory, Mail Stop 249-17, California Institute of Technology, Pasadena, CA 91125 (United States)


    Although there have been recent claims that there is a large dispersion in the abundances of the heavy neutron capture elements in the old Galactic globular cluster M92, we show that the measured dispersion for the absolute abundances of four of the rare earth elements within a sample of 12 luminous red giants in M92 ({<=}0.07 dex) does not exceed the relevant sources of uncertainty. As expected from previous studies, the heavy elements show the signature of the r-process. Their abundance ratios are essentially identical to those of M30, another nearby globular cluster of similar metallicity.

  3. The impact of non-LTE effects and granulation inhomogeneities on the derived iron and oxygen abundances in metal-poor halo stars

    E-Print Network [OSTI]

    Nataliya Shchukina; Javier Trujillo Bueno; Martin Asplund


    This paper presents the results of a detailed theoretical investigation of the impact of non-LTE effects and of granulation inhomogeneities on the derived iron and oxygen abundances in the metal-poor halo subgiant HD140283. Our analysis is based on both the `classical' one-dimensional (1D) stellar atmosphere models and on the new generation of three-dimensional (3D) hydrodynamical models. We find that the non-LTE effects on the iron abundance derived from Fe {\\sc i} lines are very important, amounting to ${\\sim}0.9$ dex and to ${\\sim}0.6$ dex in the 3D and 1D cases, respectively. On the other hand, we find that non-LTE and 3D effects have to be taken into account for a reliable determination of the iron abundance from weak Fe {\\sc ii} lines, because the significant overexcitation of their upper levels in the granular regions tend to produce emission features. As a result such Fe {\\sc ii} lines are weaker than in LTE and the abundance correction amounts to ${\\sim}0.4$ dex for the 3D case. We derive also the oxygen-to-iron abundance ratio in the metal-poor star HD140283 by using the O {\\sc i} triplet at 7772--5 \\AA and the forbidden [O {\\sc i}] line at 6300 \\AA. Interestingly, when both non-LTE and 3D effects are taken into account there still remains significant discrepancies in the iron abundances derived from Fe {\\sc i} and Fe {\\sc ii} lines, as well as in the oxygen abundances inferred from the O {\\sc i} and [O {\\sc i}] lines. We conclude that the metalicity of this type of metal-poor stars could be significantly larger than previously thought, which may have far-reaching implications in stellar astrophysics.

  4. Non-LTE metal abundances in V652 Her and HD144941

    E-Print Network [OSTI]

    N. Przybilla; M. F. Nieva; U. Heber; C. S. Jeffery


    Two evolutionary scenarios are proposed for the formation of extreme helium stars: a post-AGB star suffering from a late thermal pulse, or the merger of two white dwarfs. An identification of the evolutionary channel for individual objects has to rely on surface abundances. We present preliminary results from a non-LTE analysis of CNO, Mg and S for two unique objects, V652 Her and HD144941. Non-LTE abundance corrections for these elements range from negligible values to ~0.7 dex. Non-LTE effects typically lead to systematic shifts in the abundances relative to LTE and reduce the uncertainties.

  5. Optical Spectroscopy of Supernova Remnants in M81 and M82

    E-Print Network [OSTI]

    Lee, Myung Gyoon; Lee, Jong Hwan; Lim, Sungsoon; Jang, In Sung; Ko, Youkyung; Koo, Bon-Chul; Hwang, Narae; Kim, Sang Chul; Park, Byeong-Gon


    We present spectroscopy of 28 SNR candidates as well as one H II region in M81, and two SNR candidates in M82. Twenty six out of the M81 candidates turn out to be genuine SNRs, and two in M82 may be shocked condensations in the galactic outflow or SNRs. The distribution of [N II]/H{\\alpha} ratios of M81 SNRs is bimodal. M81 SNRs are divided into two groups in the spectral line ratio diagrams: an [O III]-strong group and an [O III]-weak group. The latter have larger sizes, and may have faster shock velocity. [N II]/H{\\alpha} ratios of the SNRs show a strong correlation with [S II]/H{\\alpha} ratios. They show a clear radial gradient in [N II]/H{\\alpha} and [S II]/H{\\alpha} ratios: dLog ([N II]/H{\\alpha})/dLog R = -0.018 {\\pm} 0.008 dex/kpc and dLog ([S II]/H{\\alpha})/dLog R = -0.016 {\\pm} 0.008 dex/kpc where R is a deprojected galactocentric distance. We estimate the nitrogen and oxygen abundance of the SNRs from the comparison with shock-ionization models. We obtain a value for the nitrogen radial gradient, dL...

  6. Oxygen abundances in planet-harbouring stars. Comparison of different abundance indicators

    E-Print Network [OSTI]

    A. Ecuvillon; G. Israelian; N. C. Santos; N. G. Shchukina; M. Mayor; R. Rebolo


    We present a detailed and uniform study of oxygen abundances in 155 solar type stars, 96 of which are planet hosts and 59 of which form part of a volume-limited comparison sample with no known planets. EW measurements were carried out for the [O I] 6300 \\AA line and the O I triplet, and spectral synthesis was performed for several OH lines. NLTE corrections were calculated and applied to the LTE abundance results derived from the O I 7771-5 \\AA\\ triplet. Abundances from [O I], the O I triplet and near-UV OH were obtained in 103, 87 and 77 dwarfs, respectively. We present the first detailed and uniform comparison of these three oxygen indicators in a large sample of solar-type stars. There is good agreement between the [O/H] ratios from forbidden and OH lines, while the NLTE triplet shows a systematically lower abundance. We found that discrepancies between OH, [O I] and the O I triplet do not exceed 0.2 dex in most cases. We have studied abundance trends in planet host and comparison sample stars, and no obvious anomalies related to the presence of planets have been detected. All three indicators show that, on average, [O/Fe] decreases with [Fe/H] in the metallicity range -0.8oxygen overabundance of 0.1-0.2dex with respect to the comparison sample.

  7. Sodium and Oxygen Abundances in the Open Cluster NGC 6791 from APOGEE H-Band Spectroscopy

    E-Print Network [OSTI]

    Cunha, Katia; Johnson, Jennifer A; Bergemann, Maria; Meszaros, Szabolcs; Shetrone, Matthew D; Souto, Diogo; Prieto, Carlos Allende; Schiavon, Ricardo P; Frinchaboy, Peter; Zasowski, Gail; Bizyaev, Dmitry; Holtzman, Jon; Perez, Ana E Garcia; Majewski, Steven R; Nidever, David; Beers, Timothy; Carrera, Ricardo; Geisler, Doug; Gunn, James; Hearty, Fred; Ivans, Inese; Martell, Sarah; Pinsonneault, Marc; Schneider, Donald P; Sobeck, Jennifer; Stello, Dennis; Stassun, Keivan G; Skrutskie, Michael; Wilson, John C


    The open cluster NGC 6791 is among the oldest, most massive and metal-rich open clusters in the Galaxy. High-resolution $H$-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) of 11 red giants in NGC 6791 are analyzed for their chemical abundances of iron, oxygen, and sodium. The abundances of these three elements are found to be homogeneous (with abundance dispersions at the level of $\\sim$ 0.05 - 0.07 dex) in these cluster red giants, which span much of the red-giant branch (T$_{\\rm eff}$ $\\sim$ 3500K - 4600K), and include two red-clump giants. From the infrared spectra, this cluster is confirmed to be among the most metal-rich clusters in the Galaxy ($$ = 0.34 $\\pm$ 0.06), and is found to have a roughly solar value of [O/Fe] and slightly enhanced [Na/Fe]. Non-LTE calculations for the studied Na I lines in the APOGEE spectral region ($\\lambda$16373.86\\AA\\ and $\\lambda$16388.85\\AA) indicate only small departures from LTE ($\\leq$ 0.04 dex) for the parameter range and metallic...

  8. Are oxygen and neon enriched in PNe and is the current solar Ne/O abundance ratio underestimated?

    E-Print Network [OSTI]

    W. Wang; X. -W. Liu


    A thorough critical literature survey has been carried out for reliable measurements of oxygen and neon abundances of planetary nebulae (PNe) and HII regions. By contrasting the results of PNe and of HII regions, we aim to address the issues of the evolution of oxygen and neon in the interstellar medium (ISM) and in the late evolutionary phases of low- and intermediate-mass stars (LIMS), as well as the currently hotly disputed solar Ne/O abundance ratio. Through the comparisons, we find that neon abundance and Ne/O ratio increase with increasing oxygen abundance in both types of nebulae, with positive correlation coefficients larger than 0.75. The correlations suggest different enrichment mechanisms for oxygen and neon in the ISM, in the sense that the growth of neon is delayed compared to oxygen. The differences of abundances between PNe and HII regions, are mainly attributed to the results of nucleosynthesis and dredge-up processes that occurred in the progenitor stars of PNe. We find that both these alpha-elements are significantly enriched at low metallicity (initial oxygen abundance oxygen in intermediate mass stars (IMS) of low initial metallicities and in more massive stars, a conjecture that requires verification by further theoretical studies. This result also strongly suggests that both the solar neon abundance and the Ne/O ratio should be revised upwards by ~0.22 dex from the Asplund, Grevesse & Sauval values or by ~0.14 dex from the Grevesse & Sauval values.

  9. Spectroscopic Constraints on the Stellar Population of Elliptical Galaxies in the Coma Cluster

    E-Print Network [OSTI]

    Bahram Mobasher; Phil. A. James


    Near-IR spectra for a sample of 31 elliptical galaxies in the Coma cluster are obtained. The galaxies are selected to be ellipticals (no lenticulars), with a large spatial distribution, covering both the core and outskirt of the cluster (ie. corresponding to regions with large density contrasts). Spectroscopic CO (2.3 micron) absorption indices, measuring contribution from intermediate-age red giant and supergiant stars to the near-IR light of the ellipticals, are then estimated. It is found that the strength of spectroscopic CO features in elliptical galaxies increases from the core (r 0.2 deg) of the Coma cluster. Using the Mg2 strengths, it is shown that the observed effect is not due to metallicity and is mostly caused by the presence of a younger population (giant and supergiant stars) in ellipticals in outskirts (low density region) of the cluster. Using the spectroscopic CO features, the origin of the scatter on the near-IR Fundamental Plane of elliptical galaxies is studied. Correcting this relation for contributions from the red giant and supergiant stars, the rms scatter reduces from 0.077dex to 0.073dex. Although measurable, the contribution from these intermediate-age stars to the scatter on the near-IR Fundamental Plane of ellipticals is only marginal. A relation is found between the CO and V-K colours of ellipticals with a slope 0.036 +/- 0.016. This is studied using stellar synthesis models.

  10. High-precision abundances of elements in solar twin stars: Trends with stellar age and elemental condensation temperature

    E-Print Network [OSTI]

    Nissen, Poul E


    HARPS spectra with S/N > 600 for 21 solar twin stars are used to determine very precise (sigma ~ 0.01 dex) differential abundances of C, O, Na, Mg, Al, Si, S, Ca, Ti, Cr, Fe, Ni, Zn, and Y in order to see how well [X/Fe] is correlated with elemental condensation temperature, Tc. In addition, precise (sigma < 0.8 Gyr) stellar ages are obtained by interpolating between Yonsei-Yale isochrones in the logg - Teff diagram. It is confirmed that the ratio between refractory and volatile elements is lower in the Sun than in most of the solar twins, but for many stars, the relation between [X/Fe] and Tc is not well defined. For several elements there is, instead, an astonishingly tight correlation between [X/Fe] and stellar age with amplitudes up to 0.2 dex over an age interval of 8 Gyr in contrast to the lack of correlation between [Fe/H] and age. While [Mg/Fe] increases with age, the s-process element yttrium shows the opposite behavior so that [Y/Mg] can be used as a sensitive chronometer for Galactic evolution. ...


    SciTech Connect (OSTI)

    Mager, Violet A.; Madore, Barry F.; Freedman, Wendy L., E-mail:, E-mail:, E-mail: [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)


    The impact of metallicity on the Cepheid period-luminosity (P L) relation is investigated using Hubble Space Telescope Advanced Camera for Surveys V and I images of M101. Variations in the reddening-free Wesenheit parameter (W), which is employed as a proxy for luminosity, are examined as a function of the radial distance from the center of M101 (and thus metallicity). We determine that there is no dependence of the slope on metallicity. However, the intercept is found to depend on metallicity by ?{sub VI} = 0.33 0.12 mag dex{sup 1} and ?{sub VI} = 0.71 0.17 mag dex{sup 1} using 2? and 3? rejection criteria, respectively. Sigma-clipping impacts the derived metallicity dependence, and the 2? criterion applied likely mitigates blending, particularly in the crowded inner regions of M101. A metallicity-corrected distance for M101 is obtained from 619 Cepheids (? = 28.96 0.11), a result that agrees with the recently determined SN Ia distance. The metallicity effects described can be bypassed by working at near and mid-infrared wavelengths (e.g., the Carnegie Hubble Program)


    SciTech Connect (OSTI)

    Luck, R. Earle [Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106-7215 (United States); Lambert, David L., E-mail:, E-mail: [McDonald Observatory, University of Texas at Austin, Austin, TX 78712 (United States)


    This paper reports on the spectroscopic investigation of 238 Cepheids in the northern sky. Of these stars, about 150 are new to the study of the galactic abundance gradient. These new Cepheids bring the total number of Cepheids involved in abundance distribution studies to over 400. In this work, we also consider systematics between various studies and also those which result from the choice of models. We find that systematic variations exist at the 0.06 dex level both between studies and model atmospheres. In order to control the systematic effects our final gradients depend only on abundances derived herein. A simple linear fit to the Cepheid data from 398 stars yields a gradient d[Fe/H]/dR{sub G} = -0.062 {+-} 0.002 dex kpc{sup -1} which is in good agreement with previously determined values. We have also re-examined the region of the 'metallicity island' of Luck et al. With the doubling of the sample in that region and our internally consistent abundances, we find that there is scant evidence for a distinct island. We also find in our sample the first reported Cepheid (V1033 Cyg) with a pronounced Li feature. The Li abundance is consistent with the star being on its redward pass toward the first giant branch.


    SciTech Connect (OSTI)

    Simmerer, Jennifer; Ivans, Inese I.; Filler, Dan [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Francois, Patrick [Paris-Meudon Observatory, France and Universite de Picardie Jules Verne, F-80080 Amiens (France); Charbonnel, Corinne [Geneva Observatory, University of Geneva, Chemin des Maillettes 51, CH-1290 Versoix (Switzerland); Monier, Richard [Laboratoire Hippolyte Fizeau, Universite Nice Sophia Antipolis, Parc Valrose, F-06000 Nice (France); James, Gaeel, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail: [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Munchen (Germany)


    We present the metallicity as traced by the abundance of iron in the retrograde globular cluster NGC 3201, measured from high-resolution, high signal-to-noise spectra of 24 red giant branch stars. A spectroscopic analysis reveals a spread in [Fe/H] in the cluster stars at least as large as 0.4 dex. Star-to-star metallicity variations are supported both through photometry and through a detailed examination of spectra. We find no correlation between iron abundance and distance from the cluster core, as might be inferred from recent photometric studies. NGC 3201 is the lowest mass halo cluster to date to contain stars with significantly different [Fe/H] values.


    SciTech Connect (OSTI)

    Da Costa, G. S.; Norris, John E.; Yong, David [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 0200 (Australia)


    We have used the high-resolution observations obtained at the Anglo-Australian Telescope with Ultra-High Resolution Facility (R {approx} 100,000) and at Gemini-S with b-HROS (R {approx} 150,000) to determine magnesium isotope ratios for seven {omega} Cen red giants that cover a range in iron abundance from [Fe/H] = -1.78 to -0.78 dex, and for two red giants in M4 (NGC 6121). The {omega} Cen stars sample both the ''primordial'' (i.e., O-rich, Na- and Al-poor) and the ''extreme'' (O-depleted, Na- and Al-rich) populations in the cluster. The primordial population stars in both {omega} Cen and M4 show ({sup 25}Mg, {sup 26}Mg)/{sup 24}Mg isotopic ratios that are consistent with those found for the primordial population in other globular clusters with similar [Fe/H] values. The isotopic ratios for the {omega} Cen extreme stars are also consistent with those for extreme population stars in other clusters. The results for the extreme population stars studied indicate that the {sup 26}Mg/{sup 24}Mg ratio is highest at intermediate metallicities ([Fe/H] < -1.4 dex), and for the highest [Al/Fe] values. Further, the relative abundance of {sup 26}Mg in the extreme population stars is notably higher than that of {sup 25}Mg, in contrast to model predictions. The {sup 25}Mg/{sup 24}Mg isotopic ratio in fact does not show any obvious dependence on either [Fe/H] or [Al/Fe] nor, intriguingly, any obvious difference between the primordial and extreme population stars.

  15. The localized chemical pollution in NGC 5253 revisited: Results from deep echelle spectrophotometry

    E-Print Network [OSTI]

    A. R. Lopez-Sanchez; C. Esteban; J. Garcia-Rojas; M. Peimbert; M. Rodriguez


    We present echelle spectrophotometry of the blue compact dwarf galaxy (BCDG) NGC 5253. The data have been taken with the Very Large Telescope UVES echelle spectrograph in the 3100 to 10400 angstroms range. We have measured the intensities of a large number of permitted and forbidden emission lines in four zones of the central part of the galaxy. In particular, we detect faint C II and O II recombination lines (RLs). This is the first time that these lines are unambiguously detected in a dwarf starburst galaxy. The physical conditions of the ionized gas have been derived using a large number of different line intensity ratios. Chemical abundances of He, N, O, Ne, S, Cl, Ar, and Fe have been determined following the standard methods. In addition, C^{++} and O^{++} abundances have been derived from pure RLs. These abundances are larger than those obtained from collisionally excited lines, (CELs) (from 0.30 to 0.40 dex for C^{++} and from 0.19 to 0.28 dex for O^{++}). This result is consistent with a temperature fluctuations parameter (t^2) between 0.050 and 0.072. We confirm previous results that indicate the presence of a localized N enrichment in certain zones of the center of the galaxy. Moreover, our results also indicate a possible slight He overabundance in the same zones. The enrichment pattern agrees with that expected for the pollution by the ejecta of massive stars in the Wolf-Rayet (WR) phase. The amount of enriched material needed to produce the observed overabundance is consistent with the mass lost by the number of WR stars estimated in the starbursts. Finally, we discuss the possible origin of the difference between abundances derived from RLs and CELs in H II regions, finding that a recent hypothesis based on the delayed enrichment by SNe ejecta inclusions seems not to explain the observed features.


    SciTech Connect (OSTI)

    Pinsonneault, Marc H.; Epstein, Courtney; Johnson, Jennifer A. [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States); Elsworth, Yvonne; Chaplin, William J. [University of Birmingham, School of Physics and Astronomy, Edgbaston, Birmingham B15 2TT (United Kingdom); Hekker, Saskia; Silva Aguirre, Victor; Stello, Dennis [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Mszros, Sz. [Astronomy Department, Indiana University, Bloomington, IN 47405 (United States); Garca, Rafael A.; Beck, Paul [Laboratoire AIM, CEA/DSM-CNRSUniversit Denis Diderot-IRFU/SAp, F-91191 Gif-sur-Yvette Cedex (France); Holtzman, Jon [Department of Astronomy, MSC 4500, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003 (United States); Mathur, Savita [Space Science Institute, 4750 Walnut street, Suite 205, Boulder, CO 80301 (United States); Garca Prez, Ana [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Girardi, Lo [Osservatorio Astronomico di PadovaINAF, Vicolo dell'Osservatorio 5, I-35122 Padova (Italy); Basu, Sarbani [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Shetrone, Matthew [University of Texas at Austin, McDonald Observatory, 32 Fowlkes Road, TX 79734-3005 (United States); Allende Prieto, Carlos [Instituto de Astrofsica de Canarias (IAC), C/Va Lactea, s/n, E-38200 La Laguna, Tenerife (Spain); An, Deokkeun [Department of Science Education, Ewha Womans University, Seoul (Korea, Republic of); Beers, Timothy C., E-mail: [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46656 (United States); and others


    We present the first APOKASC catalog of spectroscopic and asteroseismic properties of 1916 red giants observed in the Kepler fields. The spectroscopic parameters provided from the Apache Point Observatory Galactic Evolution Experiment project are complemented with asteroseismic surface gravities, masses, radii, and mean densities determined by members of the Kepler Asteroseismology Science Consortium. We assess both random and systematic sources of error and include a discussion of sample selection for giants in the Kepler fields. Total uncertainties in the main catalog properties are of the order of 80K in T {sub eff}, 0.06 dex in [M/H], 0.014 dex in log g, and 12% and 5% in mass and radius, respectively; these reflect a combination of systematic and random errors. Asteroseismic surface gravities are substantially more precise and accurate than spectroscopic ones, and we find good agreement between their mean values and the calibrated spectroscopic surface gravities. There are, however, systematic underlying trends with T {sub eff} and log g. Our effective temperature scale is between 0 and 200K cooler than that expected from the infrared flux method, depending on the adopted extinction map, which provides evidence for a lower value on average than that inferred for the Kepler Input Catalog (KIC). We find a reasonable correspondence between the photometric KIC and spectroscopic APOKASC metallicity scales, with increased dispersion in KIC metallicities as the absolute metal abundance decreases, and offsets in T {sub eff} and log g consistent with those derived in the literature. We present mean fitting relations between APOKASC and KIC observables and discuss future prospects, strengths, and limitations of the catalog data.

  17. Oxygen abundances in metal-poor subgiants as determined from [O I], O I and OH lines

    E-Print Network [OSTI]

    A. E. Garca Prez; M. Asplund; F. Primas; P. E. Nissen; B. Gustafsson


    The debate on the oxygen abundances of metal-poor stars has its origin in contradictory results obtained using different abundance indicators. To achieve a better understanding of the problem we have acquired high quality spectra with the Ultraviolet and Visual Echelle Spectrograph at VLT, with a signal-to-noise of the order of 100 in the near ultraviolet and 500 in the optical and near infrared wavelength range. Three different oxygen abundance indicators, OH ultraviolet lines around 310.0 nm, the [OI] line at 630.03 nm and the OI lines at 777.1-5 nm were observed in the spectra of 13 metal-poor subgiants with -3.0Oxygen abundances were obtained from the analysis of these indicators which was carried out assuming local thermodynamic equilibrium and plane-parallel model atmospheres. Abundances derived from OI were corrected for departures from local thermodynamic equilibrium. Stellar parameters were computed using Teff-vs-color calibrations based on the infrared flux method and Balmer line profiles, Hipparcos parallaxes and FeII lines. [O/Fe] values derived from the forbidden line at 630.03 nm are consistent with an oxygen/iron ratio that varies linearly with [Fe/H] as [O/Fe]}=-0.09(+/-0.08)[Fe/H]+0.36(+/-0.15). Values based on the OI triplet are on average 0.19+/-0.22 dex(s.d.) higher than the values based on the forbidden line while the agreement between OH ultraviolet lines and the forbidden line is much better with a mean difference of the order of -0.09+/-0.25 dex(s.d.). In general, our results follow the same trend as previously published results with the exception of the ones based on OH ultraviolet lines. In that case our results lie below the values which gave rise to the oxygen abundance debate for metal-poor stars.


    SciTech Connect (OSTI)

    Nemec, James M. [Department of Physics and Astronomy, Camosun College, Victoria, British Columbia, V8P 5J2 (Canada); Cohen, Judith G.; Sesar, Branimir [Department of Physics and Astronomy, Caltech, Pasadena, CA (United States); Ripepi, Vincenzo [INAF-Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli (Italy); Derekas, Aliz [Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, H-1121 Budapest (Hungary); Moskalik, Pawel [Copernicus Astronomical Centre, ul.Bartycka 18, 00-716, Warsaw (Poland); Chadid, Merieme [Observatoire de la Cote d'Azur, Universite de Nice, Sophia-Antipolis, UMR 6525, Parc Valrose, F-06108 Nice Cedex 02 (France); Bruntt, Hans, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail: [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark)


    Spectroscopic iron-to-hydrogen ratios, radial velocities, atmospheric parameters, and new photometric analyses are presented for 41 RR Lyrae stars (and one probable high-amplitude {delta} Sct star) located in the field-of-view of the Kepler space telescope. Thirty-seven of the RR Lyrae stars are fundamental-mode pulsators (i.e., RRab stars) of which sixteen exhibit the Blazhko effect. Four of the stars are multiperiodic RRc pulsators oscillating primarily in the first-overtone mode. Spectroscopic [Fe/H] values for the 34 stars for which we were able to derive estimates range from -2.54 {+-} 0.13 (NR Lyr) to -0.05 {+-} 0.13 dex (V784 Cyg), and for the 19 Kepler-field non-Blazhko stars studied by Nemec et al. the abundances agree will with their photometric [Fe/H] values. Four non-Blazhko RR Lyrae stars that they identified as metal-rich (KIC 6100702, V2470 Cyg, V782 Cyg and V784 Cyg) are confirmed as such, and four additional stars (V839 Cyg, KIC 5520878, KIC 8832417, KIC 3868420) are also shown here to be metal-rich. Five of the non-Blazhko RRab stars are found to be more metal-rich than [Fe/H] {approx}-0.9 dex while all of the 16 Blazhko stars are more metal-poor than this value. New P-{phi}{sub 31}{sup s}-[Fe/H] relationships are derived based on {approx}970 days of quasi-continuous high-precision Q0-Q11 long- and short-cadence Kepler photometry. With the exception of some Blazhko stars, the spectroscopic and photometric [Fe/H] values are in good agreement. Several stars with unique photometric characteristics are identified, including a Blazhko variable with the smallest known amplitude and frequency modulations (V838 Cyg)


    SciTech Connect (OSTI)

    Barro, G.; Perez-Gonzalez, P. G.; Gallego, J.; Villar, V.; Zamorano, J. [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Ashby, M. L. N. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Kajisawa, M.; Yamada, T. [Astronomical Institute, Tohoku University, Aramaki, Aoba, Sendai 9808578 (Japan); Miyazaki, S. [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)


    Based on the ultraviolet to far-infrared photometry already compiled and presented in a companion paper (Paper I), we present a detailed spectral energy distribution (SED) analysis of nearly 80,000 IRAC 3.6 + 4.5 {mu}m selected galaxies in the Extended Groth Strip. We estimate photometric redshifts, stellar masses, and star formation rates (SFRs) separately for each galaxy in this large sample. The catalog includes 76,936 sources with [3.6] {<=} 23.75 (85% completeness level of the IRAC survey) over 0.48 deg{sup 2}. The typical photometric redshift accuracy is {Delta}z/(1 + z) = 0.034, with a catastrophic outlier fraction of just 2%. We quantify the systematics introduced by the use of different stellar population synthesis libraries and initial mass functions in the calculation of stellar masses. We find systematic offsets ranging from 0.1 to 0.4 dex, with a typical scatter of 0.3 dex. We also provide UV- and IR-based SFRs for all sample galaxies, based on several sets of dust emission templates and SFR indicators. We evaluate the systematic differences and goodness of the different SFR estimations using the deep FIDEL 70 {mu}m data available in the Extended Groth Strip. Typical random uncertainties of the IR-bases SFRs are a factor of two, with non-negligible systematic effects at z {approx}> 1.5 observed when only MIPS 24 {mu}m data are available. All data products (SEDs, postage stamps from imaging data, and different estimations of the photometric redshifts, stellar masses, and SFRs of each galaxy) described in this and the companion paper are publicly available, and they can be accessed through our the Web interface utility Rainbow-navigator.

  20. Photoinduced phenomena and structural analysis associated with the spin state switching in the [Fe(II)

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    -Ecole Normale Supérieure de Lyon, Laboratoire de Chimie, UMR 5182, 46 allée d'Italie, F- 69364 Lyon Cédex 07. 5

  1. Characterizing Pleiotropic Effects of Glucocorticoids in Mice Using Heavy Water Labeling and Mass Spectrometry

    E-Print Network [OSTI]

    Roohk, Donald Jason


    de novo lipogenesis: DNL; dual energy X-ray absorptiometry:analysis using dual energy X-ray absorptiometry (DEXA) andWT; dexamethasone: DEX; dual energy X-ray absorptiometry:

  2. Groundwater and Terrestrial Water Storage,

    E-Print Network [OSTI]

    Rodell, M; Chambers, D P; Famiglietti, J S


    4.9. NOAAs Accumulated Cyclone Energy (ACE) Index in theF ig . 4.23 (a) Accumulated Cyclone Energy (ACE) In- dex perone TY). The accumulated cyclone energy (ACE) in the WNP (

  3. Separation and concentration of lower alcohols from dilute aqueous solutions

    DOE Patents [OSTI]

    Moore, Raymond H. (Richland, WA); Eakin, David E. (Kennewick, WA); Baker, Eddie G. (Richland, WA); Hallen, Richard T. (Richland, WA)


    A process for producing, from a dilute aqueous solution of a lower (C.sub.1 -C.sub.5) alcohol, a concentrated liquid solution of the alcohol in an aromatic organic solvent is disclosed. Most of the water is removed from the dilute aqueous solution of alcohol by chilling sufficiently to form ice crystals. Simultaneously, the remaining liquid is extracted at substantially the same low temperature with a liquid organic solvent that is substantially immiscible in aqueous liquids and has an affinity for the alcohol at that temperature, causing the alcohol to transfer to the organic phase. After separating the organic liquid from the ice crystals, the organic liquid can be distilled to enrich the concentration of alcohol therein. Ethanol so separated from water and concentrated in an organic solvent such as toluene is useful as an anti-knock additive for gasoline.

  4. Effects of Dexamethasone on Mesenchymal Stromal Cell Chondrogenesis and Aggrecanase Activity: Comparison of Agarose and Self-Assembling Peptide Scaffolds

    E-Print Network [OSTI]

    Florine, Emily Marie

    Objective: Dexamethasone (Dex) is a synthetic glucocorticoid that has pro-anabolic and anticatabolic effects in cartilage tissue engineering systems, though the mechanisms by which these effects are mediated are not well ...

  5. Lactoferrin inhibits dexamethasone-induced chondrocyte impairment from osteoarthritic cartilage through up-regulation of extracellular signal-regulated kinase 1/2 and suppression of FASL, FAS, and Caspase 3

    SciTech Connect (OSTI)

    Tu, Yihui [Department of Orthopaedics, Yangpu District Central Hospital Affiliated to Tongji University School of Medicine, 450 Tengyue Road, Shanghai (China)] [Department of Orthopaedics, Yangpu District Central Hospital Affiliated to Tongji University School of Medicine, 450 Tengyue Road, Shanghai (China); Xue, Huaming [Department of Orthopaedics, Yangpu District Central Hospital Affiliated to Tongji University School of Medicine, 450 Tengyue Road, Shanghai (China) [Department of Orthopaedics, Yangpu District Central Hospital Affiliated to Tongji University School of Medicine, 450 Tengyue Road, Shanghai (China); Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom); Francis, Wendy [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom)] [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom); Davies, Andrew P. [Department of Orthopaedics and Trauma, Moriston Hospital, Swansea (United Kingdom)] [Department of Orthopaedics and Trauma, Moriston Hospital, Swansea (United Kingdom); Pallister, Ian; Kanamarlapudi, Venkateswarlu [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom)] [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom); Xia, Zhidao, E-mail: [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom)] [Institute of Life Science, College of Medicine, Swansea University, Singleton Park (United Kingdom)


    Highlights: Dex exerts dose-dependant inhibition of HACs viability and induction of apoptosis. Dex-induced impairment of chondrocytes was attenuated by rhLF. ERK and FASL/FAS signaling are involved in the effects of rhLF. OA patients with glucocorticoid-induced cartilage damage may benefit from treatment with rhLF. -- Abstract: Dexamethasone (Dex) is commonly used for osteoarthritis (OA) with excellent anti-inflammatory and analgesic effect. However, Dex also has many side effects following repeated use over prolonged periods mainly through increasing apoptosis and inhibiting proliferation. Lactoferrin (LF) exerts significantly anabolic effect on many cells and little is known about its effect on OA chondrocytes. Therefore, the aim of this study is to investigate whether LF can inhibit Dex-induced OA chondrocytes apoptosis and explore its possible molecular mechanism involved in. MTT assay was used to determine the optimal concentration of Dex and recombinant human LF (rhLF) on chondrocytes at different time and dose points. Chondrocytes were then stimulated with Dex in the absence or presence of optimal concentration of rhLF. Cell proliferation and viability were evaluated using MTT and LIVE/DEAD assay, respectively. Cell apoptosis was evaluated by multi-parameter apoptosis assay kit using both confocal microscopy and flow cytometry, respectively. The expression of extracellular signal-regulated kinase (ERK), FAS, FASL, and Caspase-3 (CASP3) at the mRNA and protein levels were examined by real-time polymerase chain reaction (PCR) and immunocytochemistry, respectively. The optimal concentration of Dex (25 ?g/ml) and rhLF (200 ?g/ml) were chosen for the following experiments. rhLF significantly reversed the detrimental effect of Dex on chondrocytes proliferation, viability, and apoptosis. In addition, rhLF significantly prevented Dex-induced down-regulation of ERK and up-regulation of FAS, FASL, and CASP3. These findings demonstrated that rhLF acts as an anabolic effect on chondrocytes through significantly reversing Dex-induced chondrocytes apoptosis. This study may contribute to further investigating the clinical application of LF on OA.

  6. On the oxygen abundance in our Galaxy

    E-Print Network [OSTI]

    L. S. Pilyugin; F. Ferrini; R. V. Shkvarun


    The compilation of published spectra of Galactic HII regions with available diagnostic [OIII]4363 line has been carried out. Our list contains 71 individual measurements of 13 HII regions in the range of galactocentric distances from 6.6 to 14.8 kpc. The oxygen abundances in all the HII regions were recomputed in the same way, using the classic Te - method. The oxygen abundance at the solar galactocentric distance traced by those HII regions is in agreement with the oxygen abundance in the interstellar medium in the solar vicinity derived with high precision from the interstellar absorption lines towards stars. The derived radial oxygen abundance distribution was compared with that for HII regions from the Shaver et al. (1983) sample which is the basis of many models for the chemical evolution of our Galaxy. It was found that the original Shaver et al.'s oxygen abundances are overestimated by 0.2-0.3 dex. Oxygen abundances in HII regions from the Shaver et al. sample have been redetermined with the recently suggested P - method. The radial distribution of oxygen abundances from the Shaver et al. sample redetermined with the P - method is in agreement with our radial distribution of (O/H)_Te abundances.

  7. Dark Matter and Stellar Mass in the Luminous Regions of Disk Galaxies

    E-Print Network [OSTI]

    James Pizagno; Francisco Prada; David H. Weinberg; Hans-Walter Rix; Daniel Harbeck; Eva K. Grebel; Eric Bell; Jon Brinkmann; Jon Holtzman; Andrew West


    We investigate the correlations among stellar mass (M_*), disk scale length (R_d), and rotation velocity at 2.2 disk scale lengths (V_2.2) for a sample of 81 disk-dominated galaxies (disk/total >= 0.9) selected from the SDSS. We measure V_2.2 from long-slit H-alpha rotation curves and infer M_* from galaxy i-band luminosities (L_i) and g-r colors. We find logarithmic slopes of 2.60+/-0.13 and 3.05+/-0.12 for the L_i-V_2.2 and M_*-V_2.2 relations, somewhat shallower than most previous studies, with intrinsic scatter of 0.13 dex and 0.16 dex. Our direct estimates of the total-to-stellar mass ratio within 2.2R_d, assuming a Kroupa IMF, yield a median ratio of 2.4 for M_*>10^10 Msun and 4.4 for M_*=10^9-10^10 Msun, with large scatter at a given M_* and R_d. The typical ratio of the rotation speed predicted for the stellar disk alone to the observed rotation speed at 2.2R_d is ~0.65. The distribution of R_d at fixed M_* is broad, but we find no correlation between disk size and the residual from the M_*-V_2.2 relation, implying that this relation is an approximately edge-on view of the disk galaxy fundamental plane. Independent of the assumed IMF, this result implies that stellar disks do not, on average, dominate the mass within 2.2R_d. We discuss our results in the context of infall models of disk formation in cold dark matter halos. A model with a disk-to-halo mass ratio m_d=0.05 provides a reasonable match to the R_d-M_* distribution for spin parameters \\lambda ranging from ~0.04-0.08, and it yields a reasonable match to the mean M_*-V_2.2 relation. A model with m_d=0.1 predicts overly strong correlations between disk size and M_*-V_2.2 residual. Explaining the wide range of halo-to-disk mass ratios within 2.2R_d requires significant scatter in m_d values, with systematically lower m_d for galaxies with lower $M_*$.

  8. Oxygen enrichment in carbon-rich planetary nebulae

    E-Print Network [OSTI]

    Delgado-Inglada, Gloria; Peimbert, Manuel; Stasi?ska, Gra?yna; Morisset, Christophe


    We study the relation between the chemical composition and the type of dust present in a group of 20 Galactic planetary nebulae (PNe) that have high quality optical and infrared spectra. The optical spectra are used, together with the best available ionization correction factors, to calculate the abundances of Ar, C, Cl, He, N, Ne, and O relative to H. The infrared spectra are used to classify the PNe in two groups depending on whether the observed dust features are representative of oxygen-rich or carbon-rich environments. The sample contains one object from the halo, eight from the bulge, and eleven from the local disc. We compare their chemical abundances with nucleosynthesis model predictions and with the ones obtained in seven Galactic H II regions of the solar neighbourhood. We find evidence of O enrichment (by $\\sim$ 0.3 dex) in all but one of the PNe with carbon-rich dust (CRD). Our analysis shows that Ar, and especially Cl, are the best metallicity indicators of the progenitors of PNe. There is a tig...

  9. Heavy metals and lead isotopes in sdB stars

    E-Print Network [OSTI]

    S. O'Toole; U. Heber


    We present a detailed abundance analysis of high-resolution ultraviolet echelle spectra of five subdwarf B stars obtained with HST-STIS The goal of our observations was to test the hypothesis that pulsations in sdBs are correlated to the surface abundances of iron-group elements. We study two pulsators and three non-pulsators and determined abundances for 25 elements including the iron group and even heavier elements such as tin and lead using LTE spectrum synthesis techniques. We find strong enrichments of heavy elements up to 2.9dex with respect to solar which are probably caused by atomic diffusion processes. No clear-cut correlation between pulsations and metal abundances becomes apparent. Abundances for lead isotopes are derived from very high resolution spectra using an UV line of triply ionised lead. As Pb terminates the s-process sequence Pb isotopic abundance ratios yield important constraints. It is very difficult to measure them in hot stars. For the first time we were able to measure them in two subluminous B stars and conclude that the 207Pb/208Pb is solar.

  10. Light Element Abundance Patterns in the Orion Association: I) HST Observations of Boron in G-dwarfs

    E-Print Network [OSTI]

    K. Cunha; V. Smith; E. Parizot; D. Lambert


    The boron abundances for two young solar-type members of the Orion association, BD -6 1250 and HD 294297, are derived from HST STIS spectra of the B I transition at 2496.771 A. The best-fit boron abundances for the target stars are 0.13 and 0.44 dex lower than the solar meteoritic value of log e(B)=2.78. An anticorrelation of boron and oxygen is found for Orion when these results are added to previous abundances obtained for 4 B-type stars and the G-type star BD -5 1317. An analysis of the uncertainties in the abundance calculations indicates that the observed anticorrelation is probably real. The B versus O relation observed in the Orion association does not follow the positive correlation of boron versus oxygen which is observed for the field stars with roughly solar metallicity. The observed anticorrelation can be accounted for by a simple model in which two poorly mixed components of gas (supernova ejecta and boron-enriched ambient medium) contribute to the new stars that form within the lifetime of the association. This model predicts an anticorrelation for Be as well, at least as strong as for boron.

  11. Oxygen abundances in G- and F-type stars from HARPS

    E-Print Network [OSTI]

    de Lis, S Bertran; Adibekyan, V Zh; Santos, N C; Sousa, S G


    We present a detailed and uniform study of oxygen abundance from two different oxygen lines at 6158$\\AA$ and 6300$\\AA$ in a large sample of solar-type stars. The results are used to check the behaviour of these spectral lines as oxygen abundance indicators and to study the evolution of oxygen in thick and thin disk populations of the Galaxy. Equivalent width measurements were carried out for the [OI]~6158$\\AA$ and OI~6300$\\AA$ lines. LTE abundances were obtained from these two lines in 610 and 535 stars, respectively. We were able to measure oxygen abundance from both indicators in 447 stars, enabling us, for the first time, to compare them in a uniform way. Careful error analysis has been performed. We found that oxygen abundances derived from the 6158$\\AA$ and 6300$\\AA$ lines agree to within 0.1dex in 58\\% of the stars in our sample, and this result improves for higher signal-to-noise values. We confirm an oxygen enhancement in stars of the thick disk, as has also been seen for other $\\alpha$-elements. The ...

  12. Oxygen abundance in the Sloan Digital Sky Survey

    E-Print Network [OSTI]

    F. Shi; X. Kong; F. Z. Cheng


    We present two samples of $\\hii$ galaxies from the Sloan Digital Sky Survey (SDSS) spectroscopic observations data release 3. The electron temperatures($T_e$) of 225 galaxies are calculated with the photoionized $\\hii$ model and $T_e$ of 3997 galaxies are calculated with an empirical method. The oxygen abundances from the $T_e$ methods of the two samples are determined reliably. The oxygen abundances from a strong line metallicity indicator, such as $R_{23}$, $P$, $N2$, and $O3N2$, are also calculated. We compared oxygen abundances of $\\hii$ galaxies obtained with the $T_e$ method, $R_{23}$ method, $P$ method, $N2$ method, and $O3N2$method. The oxygen abundances derived with the $T_e$ method are systematically lower by $\\sim$0.2 dex than those derived with the $R_{23}$ method, consistent with previous studies based on $\\hii$ region samples. No clear offset for oxygen abundance was found between $T_e$ metallicity and $P$, $N2$ and $O3N2$ metallicity. When we studied the relation between N/O and O/H, we found that in the metallicity regime of $\\zoh > 7.95$, the large scatter of the relation can be explained by the contribution of small mass stars to the production of nitrogen. In the high metallicity regime, $\\zoh > 8.2$, nitrogen is primarily a secondary element produced by stars of all masses.

  13. Beryllium in the Ultra-Lithium-Deficient,Metal-Poor Halo Dwarf, G186-26

    E-Print Network [OSTI]

    Ann Merchant Boesgaard; Megan C. Novicki


    The vast majority of low-metal halo dwarfs show a similar amount of Li; this has been attributed to the Li that was produced in the Big Bang. However, there are nine known halo stars with T $>$ 5900 K and [Fe/H] $<$ $-$1.0 that are ultra-Li-deficient. We have looked for Be in the very low metallicity star, G 186-26 at [Fe/H] = $-$2.71, which is one of the ultra-Li-deficient stars. This star is also ultra-Be deficient. Relative to Be in the Li-normal stars at [Fe/H] = $-$2.7, G 182-26 is down in Be by more than 0.8 dex. Of two potential causes for the Li-deficiency -- mass-transfer in a pre-blue straggler or extra rotationally-induced mixing in a star that was initially a very rapid rotator -- the absence of Be favors the blue-straggler hypothesis, but the rotation model cannot be ruled-out completely.

  14. The Gaia-ESO Survey: Detailed Abundances in the Metal-poor Globular Cluster NGC 4372

    E-Print Network [OSTI]

    Roman, I San; Geisler, D; Villanova, S; Kacharov, N; Koch, A; Carraro, G; Tautvaiiene, G; Vallenari, A; Alfaro, E J; Bensby, T; Flaccomio, E; Francois, P; Korn, A J; Pancino, E; Recio-Blanco, A; Smiljanic, R; Bergemann, M; Costado, M T; Damiani, F; Heiter, U; Hourihane, A; Jofr, P; Lardo, C; de Laverny, P; Masseron, T; Morbidelli, L; Sbordone, L; Sousa, S G; Worley, C C; Zaggia, S


    We present the abundance analysis for a sample of 7 red giant branch stars in the metal-poor globular cluster NGC 4372 based on UVES spectra acquired as part of the Gaia-ESO Survey. This is the first extensive study of this cluster from high resolution spectroscopy. We derive abundances of O, Na, Mg, Al, Si, Ca, Sc, Ti, Fe, Cr, Ni, Y, Ba, and La. We find a metallicity of [Fe/H] = -2.19 $\\pm$ 0.03 and find no evidence for a metallicity spread. This metallicity makes NGC 4372 one of the most metal-poor galactic globular clusters. We also find an {\\alpha}-enhancement typical of halo globular clusters at this metallicity. Significant spreads are observed in the abundances of light elements. In particular we find a Na-O anti-correlation. Abundances of O are relatively high compared with other globular clusters. This could indicate that NGC 4372 was formed in an environment with high O for its metallicity. A Mg-Al spread is also present which spans a range of more than 0.5 dex in Al abundances. Na is correlated wit...

  15. Origin of the heavy elements in HD 140283. Measurement of europium abundance

    E-Print Network [OSTI]

    Mello, C Siqueira; Spite, M; Spite, F


    HD 140283 is a nearby (V=7.7) subgiant metal-poor star, extensively analysed in the literature. Although many spectra have been obtained for this star, none showed a signal-to-noise (S/N) ratio high enough to enable a very accurate derivation of abundances from weak lines. The detection of europium proves that the neutron-capture elements in this star originate in the r-process, and not in the s-process, as recently claimed in the literature. Based on the OSMARCS 1D LTE atmospheric model and with a consistent approach based on the spectrum synthesis code Turbospectrum, we measured the europium lines at 4129 {\\AA} and 4205 {\\AA}, taking into account the hyperfine structure of the transitions. The spectrum, obtained with a long exposure time of seven hours at the Canada-France-Hawaii Telescope (CFHT), has a resolving power of 81000 and a S/N ratio of 800 at 4100 {\\AA}. We were able to determine the abundance A(Eu)=-2.35 dex, compatible with the value predicted for the europium from the r-process. The abundance ...

  16. A chemical trompe-l'\\oe{}il: no iron spread in the globular cluster M22

    E-Print Network [OSTI]

    Mucciarelli, A; Massari, D; Pancino, E; Stetson, P B; Ferraro, F R; Lanzoni, B; Lardo, C


    We present the analysis of high-resolution spectra obtained with UVES and UVES-FLAMES at the Very Large Telescope of 17 giants in the globular cluster M22, a stellar system suspected to have an intrinsic spread in the iron abundance. We find that when surface gravities are derived spectroscopically (by imposing to obtain the same iron abundance from FeI and FeII lines) the [Fe/H] distribution spans ~0.5 dex, according to previous analyses. However, the gravities obtained in this way correspond to unrealistic low stellar masses (0.1-0.5 Msun) for most of the surveyed giants. Instead, when photometric gravities are adopted, the [FeII/H] distribution shows no evidence of spread at variance with the [FeI/H] distribution. This difference has been recently observed in other clusters and could be due to non-local thermodynamical equilibrium effects driven by over-ionization mechanisms, that mainly affect the neutral species (thus providing lower [FeI/H]) but leave [FeII/H] unaltered. We confirm that the s-process el...

  17. Chemical Abundances in NGC 5053: A Very Metal-Poor and Dynamically Complex Globular Cluster

    E-Print Network [OSTI]

    Boberg, Owen M; Vesperini, Enrico


    NGC 5053 provides a rich environment to test our understanding of the complex evolution of globular clusters (GCs). Recent studies have found that this cluster has interesting morphological features beyond the typical spherical distribution of GCs, suggesting that external tidal effects have played an important role in its evolution and current properties. Additionally, simulations have shown that NGC 5053 could be a likely candidate to belong to the Sagittarius dwarf galaxy (Sgr dSph) stream. Using the Wisconsin-Indiana-Yale-NOAO-Hydra multi-object spectrograph, we have collected high quality (signal-to-noise ratio $\\sim$ 75-90), medium-resolution spectra for red giant branch stars in NGC 5053. Using these spectra we have measured the Fe, Ca, Ti, Ni, Ba, Na, and O abundances in the cluster. We measure an average cluster [Fe/H] abundance of -2.45 with a standard deviation of 0.04 dex, making NGC 5053 one of the most metal-poor GCs in the Milky Way (MW). The [Ca/Fe], [Ti/Fe], and [Ba/Fe] we measure are consist...

  18. Iron and s-elements abundance variations in NGC5286: comparison with anomalous globular clusters and Milky Way satellites

    E-Print Network [OSTI]

    Marino, A F; Karakas, A I; Casagrande, L; Yong, D; Shingles, L; Da Costa, G; Norris, J E; Stetson, P B; Lind, K; Asplund, M; Collet, R; Jerjen, H; Sbordone, L; Aparicio, A; Cassisi, S


    We present a high resolution spectroscopic analysis of 62 red giants in the Milky Way globular cluster NGC5286. We have determined abundances of representative light proton-capture, alpha, Fe-peak and neutron-capture element groups, and combined them with photometry of multiple sequences observed along the colour-magnitude diagram. Our principal results are: (i) a broad, bimodal distribution in s-process element abundance ratios, with two main groups, the s-poor and s-rich groups; (ii) substantial star-to-star Fe variations, with the s-rich stars having higher Fe, e.g. _s-rich - _s-poor ~ 0.2~dex; and (iii) the presence of O-Na-Al (anti-)correlations in both stellar groups. We have defined a new photometric index, c_{BVI}=(B-V)-(V-I), to maximise the separation in the colour-magnitude diagram between the two stellar groups with different Fe and s-element content, and this index is not significantly affected by variations in light elements (such as the O-Na anticorrelation). The variations in the overall metal...

  19. Variable stars and stellar populations in Andromeda XXI: II. Another merged galaxy satellite of M31?

    E-Print Network [OSTI]

    Cusano, F; Clementini, G; Cignoni, M; Federici, L; Marconi, M; Musella, I; Ripepi, V; Speziali, R; Sani, E; Merighi, R


    B and V time-series photometry of the M31 dwarf spheroidal satellite Andromeda XXI (And XXI) was obtained with the Large Binocular Cameras at the Large Binocular Telescope. We have identified 50 variables in And XXI, of which 41 are RR Lyrae stars (37 fundamental-mode RRab, and 4 first-overtone RRc, pulsators) and 9 are Anomalous Cepheids (ACs). The average period of the RRab stars ( = 0.64 days) and the period-amplitude diagram place And~XXI in the class of Oosterhoff II - Oosterhoff-Intermediate objects. From the average luminosity of the RR Lyrae stars we derived the galaxy distance modulus of (m-M)$_0$=$24.40\\pm0.17$ mag, which is smaller than previous literature estimates, although still consistent with them within 1 $\\sigma$. The galaxy color-magnitude diagram shows evidence for the presence of three different stellar generations in And~XXI: 1) an old ($\\sim$ 12 Gyr) and metal poor ([Fe/H]=$-$1.7 dex) component traced by the RR Lyrae stars; 2) a slightly younger (10-6 Gyr) and more metal rich ([Fe/H]=$-...

  20. Evidence for temporal evolution in the M33 disc as traced by its star clusters

    E-Print Network [OSTI]

    Beasley, Michael A; Gallart, Carme; Sarajedini, Ata; Aparicio, Antonio


    We present precision radial velocities and stellar population parameters for 77 star clusters in the Local Group galaxy M33. Our GTC and WHT observations sample both young, massive clusters and known/candidate globular clusters, spanning ages ~ 10^6 - 10^10 yr, and metallicities, [M/H] ~-1.7 to solar. The cluster system exhibits an age-metallicity relation; the youngest clusters are the most metal-rich. When compared to HI data, clusters with [M/H] ~ -1.0 and younger than ~ 4 Gyr are clearly identified as a disc population. The clusters show evidence for strong time evolution in the disc radial metallicity gradient (d[M/H]dt / dR = 0.03 dex/kpc/Gyr). The oldest clusters have stronger, more negative gradients than the youngest clusters in M33. The clusters also show a clear age-velocity dispersion relation. The line of sight velocity dispersions of the clusters increases with age similar to Milky Way open clusters and stars. The general shape of the relation is reproduced by disc heating simulations, and the s...

  1. Atomic data for S IItoward better diagnostics of chemical evolution in high-redshift galaxies

    SciTech Connect (OSTI)

    Kisielius, Romas; Bogdanovich, Pavel [Institute of Theoretical Physics and Astronomy, Vilnius University, A. Gotauto 12, LT-01108 (Lithuania); Kulkarni, Varsha P. [Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208 (United States); Ferland, Gary J.; Lykins, Matt L. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States)


    Absorption-line spectroscopy is a powerful tool used to estimate element abundances in both the nearby and distant universe. The accuracy of the abundances thus derived is naturally limited by the accuracy of the atomic data assumed for the spectral lines. We have recently started a project to perform new extensive atomic data calculations used for optical/UV spectral lines in the plasma modeling code Cloudy using state of the art quantal calculations. Here, we demonstrate our approach by focussing on S II, an ion used to estimate metallicities for Milky Way interstellar clouds as well as distant damped Lyman-alpha (DLA) and sub-DLA absorber galaxies detected in the spectra of quasars and gamma-ray bursts. We report new extensive calculations of a large number of energy levels of S II, and the line strengths of the resulting radiative transitions. Our calculations are based on the configuration interaction approach within a numerical Hartree-Fock framework, and utilize both non-relativistic and quasirelativistic one-electron radial orbitals. The results of these new atomic calculations are then incorporated into Cloudy and applied to a lab plasma, and a typical DLA, for illustrative purposes. The new results imply relatively modest changes (?0.04 dex) to the metallicities estimated from S II in past studies. These results will be readily applicable to other studies of S II in the Milky Way and other galaxies.

  2. Energy transport, overshoot, and mixing in the atmospheres of M-type main- and pre-main-sequence objects

    E-Print Network [OSTI]

    H. -G. Ludwig; F. Allard; P. H. Hauschildt


    We constructed hydrodynamical model atmospheres for mid M-type main-, as well as pre-main-sequence (PMS) objects. Despite the complex chemistry encountered in these cool atmospheres a reasonably accurate representation of the radiative transfer is possible, even in the context of time-dependent and three-dimensional models. The models provide detailed information about the morphology of M-type granulation and statistical properties of the convective surface flows. In particular, we determined the efficiency of the convective energy transport, and the efficiency of mixing by convective overshoot. The convective transport efficiency was expressed in terms of an equivalent mixing-length parameter alpha in the formulation of mixing-length theory (MLT) given by Mihalas (1978). Alpha amounts to values around 2 for matching the entropy of the deep, adiabatically stratified regions of the convective envelope, and lies between 2.5 and 3.0 for matching the thermal structure of the deep photosphere. For current spectral analysis of PMS objects this implies that MLT models based on alpha=2.0 overestimate the effective temperature by 100 K and surface gravities by 0.25 dex. The average thermal structure of the formally convectively stable layers is little affected by convective overshoot and wave heating, i.e., stays close to radiative equilibrium conditions. Our models suggest that the rate of mixing by convective overshoot declines exponentially with geometrical distance to the Schwarzschild stability boundary. It increases at given effective temperature with decreasing gravitational acceleration.

  3. Chemical abundances in the extremely carbon-rich and xenon-rich halo planetary nebula H4-1

    SciTech Connect (OSTI)

    Otsuka, Masaaki [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Tajitsu, Akito, E-mail:, E-mail: [Subaru Telescope, NAOJ, 650 North A'ohoku Place, Hilo, HI 96720 (United States)


    We performed detailed chemical abundance analysis of the extremely metal-poor ([Ar/H] ? 2) halo planetary nebula (PN) H4-1 based on the multi-wavelength spectra from Subaru/HDS, GALEX, SDSS, and Spitzer/IRS and determined the abundances of 10 elements. The C and O abundances were derived from collisionally excited lines (CELs) and are almost consistent with abundances from recombination lines (RLs). We demonstrated that the large discrepancy in the C abundance between CEL and RL in H4-1 can be solved using the temperature fluctuation model. We reported the first detection of the [Xe III] ?5846 line in H4-1 and determination of its elemental abundance ([Xe/H] > +0.48). H4-1 is the most Xe-rich PN among the Xe-detected PNe. The observed abundances are close to the theoretical prediction by a 2.0 M {sub ?} single star model with an initially element rich ([r/Fe] = +2.0 dex) rapid neutron-capture process (r-process). The observed Xe abundance would be a product of the r-process in primordial supernovae. The [C/O]-[Ba/(Eu or Xe)] diagram suggests that the progenitor of H4-1 shares the evolution with carbon-enhanced metal-poor (CEMP)-r/s and CEMP-no stars. The progenitor of H4-1 is presumably a binary formed in an r-process-rich environment.

  4. The Araucaria Project. The Distance to the Local Group Galaxy WLM from Cepheid Variables discovered in a Wide-Field Imaging Survey

    E-Print Network [OSTI]

    G. Pietrzynski; W. Gieren; A. Udalski; I. Soszynski; F. Bresolin; R. P. Kudritzki; A. Garcia; D. Minniti; R. Mennickent; O. Szewczyk; M. Szymanski; M. Kubiak; L. Wyrzykowski


    We have conducted an extensive wide-field imaging survey for Cepheid variables in the Local Group irregular galaxy WLM. From data obtained on 101 nights, we have discovered 60 Cepheids which include 14 of the 15 Cepheid variables previously detected by Sandage and Carlson. Down to a period of 3 days, our Cepheid survey in WLM should be practically complete. Importantly, we have found for the first time a long-period Cepheid (P=54.2 days) in this galaxy, alleviating the puzzle that WLM with its many blue, massive stars does not contain Cepheids with periods longer than about 10 days. Our data define tight period-luminosity relations in V, I and the reddening-free Wesenheit magnitude ${\\rm W}_{\\rm I}$ which are all extremely well fit by the corresponding slopes of the LMC Cepheid PL relation, suggesting no change of the PL relation slope down to a Cepheid metal abundance of about -1.0 dex, in agreement with other recent studies. We derive a true distance modulus to WLM of 25.144 $\\pm$0.03 (r) $\\pm$0.07 (s) mag from our data, in good agreement with the earlier 24.92 $\\pm$ 0.21 mag determination of Lee, Freedman and Madore (1993a) from Cepheid variables. The quoted value of the systematic uncertainty does not include the contribution from the LMC distance which we have assumed to be 18.50 mag, as in the previous papers in our project.

  5. The Star Formation Histories of Local Group Dwarf Galaxies III. Characterizing Quenching in Low-Mass Galaxies

    E-Print Network [OSTI]

    Weisz, Daniel R; Skillman, Evan D; Holtzman, Jon; Gilbert, Karoline M; Dalcanton, Julianne J; Williams, Benjamin F


    We explore the quenching of low-mass galaxies (10^4 < Mstar < 10^8 Msun) as a function of lookback time using the star formation histories (SFHs) of 38 Local Group dwarf galaxies. The SFHs were derived from analyzing color-magnitude diagrams of resolved stellar populations in archival Hubble Space Telescope/Wide Field Planetary Camera 2 imaging. We find: (1) Lower mass galaxies quench earlier than higher mass galaxies; (2) Inside of virial radius there is no correlation between a satellite's current proximity to a massive host and its quenching epoch; (3) There are hints of systematic differences in quenching times of M31 and Milky Way (MW) satellites, although the sample sample size and uncertainties in the SFHs of M31 dwarfs prohibit definitive conclusions. Combined with literature results, we qualitatively consider the redshift evolution (z=0-1) of the quenched galaxy fraction over ~7 dex in stellar mass (10^4 < Mstar < 10^11.5 Msun). The quenched fraction of all galaxies generally increases to...

  6. s- and r-process element abundances in the CMD of 47 Tucanae using the Robert Stobie Spectrograph on SALT

    E-Print Network [OSTI]

    C. C. Worley; P. L. Cottrell; E. C. Wylie de Boer


    A recent study by Wylie et al 2006 has revealed that s-process element abundances are enhanced relative to iron in both red giant branch and asymptotic giant branch stars of 47 Tucanae. A more detailed investigation into s-process element abundances throughout the colour-magnitude diagram of 47 Tucanae is vital in order to determine whether the observed enhancements are intrinsic to the cluster. This paper explores this possibility through observational and theoretical means. The visibility of s- and r-process element lines in synthetic spectra of giant and dwarf stars throughout the colour magnitude diagram of 47 Tucanae has been explored. It was determined that a resolving power of 10 000 was sufficient to observe s-process element abundance variations in globular cluster giant branch stars. These synthetic results were compared with the spectra of eleven 47 Tucanae giant branch stars observed during the performance verification of the Robert Stobie Spectrograph on the Southern African Large Telescope. Three s-process elements, Zr, Ba, Nd, and one r-process element, Eu, were investigated. No abundance variations were found such that [X/Fe] = 0.0 +/- 0.5 dex. It was concluded that this resolving power, R ~ 5000, was not sufficient to obtain exact abundances but upper limits on the s-process element abundances could be determined.

  7. The cosmic growth of the active black hole population at 1in zCOSMOS, VVDS and SDSS

    E-Print Network [OSTI]

    Schulze, A; Gavignaud, I; Schramm, M; Silverman, J; Merloni, A; Zamorani, G; Hirschmann, M; Mainieri, V; Wisotzki, L; Shankar, F; Fiore, F; Koekemoer, A M; Temporin, G


    We present a census of the active black hole population at 1in the AGN luminosity function (AGN LF), into its physical processes of black hole mass downsizing and accretion rate evolution. We are utilizing type 1 AGN samples from 3 optical surveys (VVDS, zCOSMOS and SDSS), that cover a wide range of 3 dex in luminosity over our redshift interval of interest. We investigate the cosmic evolution of the AGN population as a function of AGN luminosity, black hole mass and accretion rate. Compared to z = 0 we find a distinct change in the shape of the BHMF and the ERDF, consistent with downsizing in black hole mass. The active fraction or duty cycle of type 1 AGN at z~1.5 is almost flat as...

  8. Chemical Abundances in Twelve Red Giants of the Large Magellanic Cloud from High-Resolution Infrared Spectroscopy

    E-Print Network [OSTI]

    V. V. Smith; K. H. Hinkle; K. Cunha; B. Plez; D. L. Lambert; C. A. Pilachowski; B. Barbuy; J. Melendez; S. Balachandran; M. S. Bessell; D. P. Geisler; J. E. Hesser; C. Winge


    High-resolution infrared spectra (R=50,000) have been obtained for twelve red-giant members of the LMC with the Gemini South 8.3-meter telescope plus Phoenix spectrometer. Quantitative chemical abundances of carbon-12, carbon-13, nitrogen-14, and oxygen-16 were derived from molecular lines of CO, CN, and OH, while sodium, scandium, titanium, and iron abundances were derived from neutral atomic lines. The LMC giants have masses from about 1 to 4 solar masses and span a metallicity range from [Fe/H]= -1.1 to -0.3. The program red giants all show evidence of first dredge-up mixing, with low 12C/13C ratios, and low 12C correlated with high 14N abundances. Comparisons of the oxygen-to-iron ratios in the LMC and the Galaxy indicate that the trend of [O/Fe] versus [Fe/H] in the LMC falls about 0.2 dex below the Galactic trend. Such an offset can be modeled as due to an overall lower rate of supernovae per unit mass in the LMC relative to the Galaxy, as well as a slightly lower ratio of supernovae of type II to supernovae of type Ia.

  9. Three-dimensional hydrodynamical CO5BOLD model atmospheres of red giant stars. IV. Oxygen diagnostics in extremely metal-poor red giants with infrared OH lines

    E-Print Network [OSTI]

    Dobrovolskas, V; Bonifacio, P; Caffau, E; Ludwig, H -G; Steffen, M; Spite, M


    Context. Although oxygen is an important tracer of Galactic chemical evolution, measurements of its abundance in the atmospheres of the oldest Galactic stars are still scarce and rather imprecise. At the lowest end of the metallicity scale, oxygen can only be measured in giant stars and in most of cases such measurements rely on a single forbidden [O I] 630 nm line that is very weak and frequently blended with telluric lines. Although molecular OH lines located in the ultraviolet and infrared could also be used for the diagnostics, oxygen abundances obtained from the OH lines and the [O I] 630 nm line are usually discrepant to a level of ~0.3-0.4 dex. Aims. We study the influence of convection on the formation of the infrared (IR) OH lines and the forbidden [O I] 630 nm line in the atmospheres of extremely metal-poor (EMP) red giant stars. Methods. We used high-resolution and high signal-to-noise ratio spectra of four EMP red giant stars obtained with the VLT CRIRES spectrograph. For each EMP star, 4-14 IR OH...

  10. Type II Cepheids in the Milky Way disc. Chemical composition of two new W Vir stars: DD Vel and HQ Car

    E-Print Network [OSTI]

    Lemasle, B; Bono, G; Franois, P; Saviane, I; Yegorova, I; Genovali, K; Inno, L; Galazutdinov, G; da Silva, R


    A robust classification of Cepheids into their different sub-classes and, in particular, between classical and Type II Cepheids, is necessary to properly calibrate the period-luminosity relations and for populations studies in the Galactic disc. Type II Cepheids are, however, very diverse, and classifications based either on intrinsic (period, light curve) or external parameters (e.g., [Fe/H], |z|) do not provide a unique classification. We want to ascertain the classification of two Cepheids, HQ Car and DD Vel, that are sometimes classified as classical Cepheids and sometimes as Type II Cepheids. To achieve this goal, we examine both their chemical composition and the presence of specific features in their spectra. We find emission features in the H{\\alpha} and in the 5875.64 {\\AA} He I lines that are typical of W Vir stars. The [Na/Fe] (or [Na/Zn]) abundances are typical of thick-disc stars, while BL Her stars are Na-overabundant ([Na/Fe]>+0.5 dex). Finally, the two Cepheids show a possible (HQ Car) or prob...

  11. The beryllium abundance in the very metal-poor halo star G 64-12 from VLT/UVES observations

    E-Print Network [OSTI]

    F. Primas; M. Asplund; P. E. Nissen; V. Hill


    We report on a new spectroscopic analysis of the very metal deficient star G 64-12 ([Fe/H]=-3.3), aimed at determining, for the first time, its Be content. The spectra were observed during the Science Verification of UVES, the ESO VLT Ultraviolet and Visible Echelle Spectrograph. The high resolution (~48,000) and high S/N (~130 per pixel) achieved at the wavelengths of the BeII resonance doublet allowed an accurate determination of its abundance: log N(Be/H) = -13.10 +/- 0.15 dex. The Be abundance is significantly higher than expected from previous measurements of Be in stars of similar metallicity (3D and NLTE corrections acting to make a slightly higher value than an LTE analysis). When compared to iron, the high [Be/Fe] ratio thus found may suggest a flattening in the beryllium evolutionary trend at the lowest metallicity end or the presence of dispersion at early epochs of galactic evolution.

  12. Color-Magnitude Diagram Constraints on the Metallicities, Ages, and Star Formation History of the Stellar Populations in the Carina Dwarf Spheroidal Galaxy

    E-Print Network [OSTI]

    VandenBerg, Don A; Brown, Thomas M


    Victoria-Regina isochrones for $-0.4 \\le$ [alpha/Fe] $\\le +0.4$ and a wide range in [Fe/H], along with complementary zero-age horizontal branch (ZAHB) loci, have been applied to the color-magnitude diagram (CMD) of Carina. The color transformations that we have used have been "calibrated" so that isochrones provide excellent fits to the $[(B-V)_0,\\,M_V]$-diagrams of M3 and M92, when well supported estimates of the globular cluster (GC) reddenings and metallicities are assumed. The adopted distance moduli, for both the GCs and Carina, are based on our ZAHB models, which are able to reproduce the old HB component (as well as the luminosity of the HB clump) of the dwarf spheroidal galaxy quite well --- even if it spans a range in [Fe/H] of ~ 1.5 dex, provided that [alpha/Fe] varies with [Fe/H] in approximately the way that has been derived spectroscopically. Ages derived here agree reasonably well with those found previously for the old and intermediate-age turnoff stars, as well as for the period of negligible ...

  13. Susceptibility to Diet-Induced Hepatic Steatosis and Glucocorticoid Resistance in FK506-Binding Protein

    E-Print Network [OSTI]

    Toledo, University of

    (peroxisome proliferator-activated re- ceptor , fatty acid synthase, and sterol regulatory element- boxy kinase, glucose 6 phosphatase, and pyruvate dehydrogenase kinase 4), whereas muscle and adipose, cyclophilin-40; Dex, dexamethasone; ER, estrogen receptor; FAS, fatty acid synthase; FFA, free fatty acid

  14. Keck-I MOSFIRE spectroscopy of compact star-forming galaxies at z$\\gtrsim$2: High velocity dispersions in progenitors of compact quiescent galaxies

    E-Print Network [OSTI]

    Barro, G; Koo, D C; Dekel, A; Kassin, S A; Kocevski, D D; Faber, S M; van der Wel, A; Guo, Y; Perez-Gonzalez, P G; Toloba, E; Fang, J J; Pacifici, C; Simons, R; Campbell, R D; Ceverino, D; Finkelstein, S L; Goodrich, B; Kassis, M; Koekemoer, A M; Konidaris, N P; Livermore, R C; Lyke, J E; Mobasher, B; Nayyeri, H; Peth, M; Primack, J R; Rizzi, L; Somerville, R S; Wirth, G D; Zolotov, A


    We present Keck-I MOSFIRE near-infrared spectroscopy for a sample of 13 compact star-forming galaxies (SFGs) at redshift $2\\leq z \\leq2.5$ with star formation rates of SFR$\\sim$100M$_{\\odot}$ y$^{-1}$ and masses of log(M/M$_{\\odot}$)$\\sim10.8$. Their high integrated gas velocity dispersions of $\\sigma_{\\rm{int}}$=230$^{+40}_{-30}$ km s$^{-1}$, as measured from emission lines of H$_{\\alpha}$ and [OIII], and the resultant M$_{\\star}-\\sigma_{\\rm{int}}$ relation and M$_{\\star}$$-$M$_{\\rm{dyn}}$ all match well to those of compact quiescent galaxies at $z\\sim2$, as measured from stellar absorption lines. Since log(M$_{\\star}$/M$_{\\rm{dyn}}$)$=-0.06\\pm0.2$ dex, these compact SFGs appear to be dynamically relaxed and more evolved, i.e., more depleted in gas and dark matter ($infusion of external gas, depletion timescales are short, less than $\\sim$300 Myr. This discovery adds another link to our new dynamical chain of evidence...

  15. Beryllium in Disk and Halo Stars -- Evidence for a Beryllium Dispersion in Old Stars

    E-Print Network [OSTI]

    Ann Merchant Boesgaard; Megan C. Novicki


    The study of Be in stars of differing metal content can elucidate the formation mechanisms and the Galactic chemical evolution of Be. We have obtained high-resolution, high signal-to-noise spectra of the resonance lines of Be II in eight stars with the high-dispersion spectrograph (HDS) on the Subaru 8.2 m telescope on Mauna Kea. Abundances of Be have been determined through spectrum synthesis. The stars with [Fe/H] values > -1.1 conform to the published general trend of Be vs Fe. We have confirmed the high Be abundance in HD 94028 and have found a similarly high Be abundance in another star, HD 132475, at the same metallicity: [Fe/H] = -1.5. These two stars are 0.5 - 0.6 dex higher in Be than the Be-Fe trend. While that general trend contains the evidence for a Galaxy-wide enrichment in Be and Fe, the higher Be abundances in those two stars indicates local Be enrichments. Possible enrichment mechanisms include hypernovae and multiple supernova explosions contained in a superbubble. The star G 64-37 has [Fe/] = -3.2; we have determined its Be abundance to look for evidence of a Be plateau. It's Be abundance appears to extend the Be-Fe trend to lower Fe abundances without any evidence for a plateau as had been indicated by a high Be abundance in another very metal-poor star, G 64-12. Although these two stars have similar Be abundances within the errors, it could be that their different Be values may be indicating that a Be dispersion exists even at the lowest metallicities.

  16. Beryllium abundance in turn-off stars of NGC 6752

    E-Print Network [OSTI]

    Luca Pasquini; Piercarlo Bonifacio; Sofia Randich; Daniele Galli; Raffaele G. Gratton; B. Wolff


    Aims: To measure the beryllium abundance in two TO stars of the Globular Cluster NGC 6752, one oxygen rich and sodium poor, the other presumably oxygen poor and sodium rich. Be abundances in these stars are used to put on firmer grounds the hypothesis of Be as cosmochronometer and to investigate the formation of Globular Clusters. Method:We present near UV spectra with resolution R$\\sim 45000$ obtained with the UVES spectrograph on the 8.2m VLT Kueyen telescope, analysed with spectrum synthesis based on plane parallel LTE model atmospheres. Results:Be is detected in the O rich star with log(Be/H)=-12.04 $\\pm$0.15, while Be is not detected in the other star for which we obtain the upper limit log(Be/H)$<$-12.2. A large difference in nitrogen abundance (1.6 dex) is found between the two stars. Conclusions:The Be measurement is compatible with what found in field stars with the same [Fe/H] and [O/H]. The 'Be age' of the cluster is found to be 13.3 Gyrs, in excellent agreement with the results from main sequence fitting and stellar evolution. The presence of Be confirms the results previously obtained for the cluster NGC 6397 and supports the hypothesis that Be can be used as a clock for the early formation of the Galaxy. Since only an upper limit is found for the star with low oxygen abundance, we cannot decide between competing scenarios of Globular Cluster formation, but we can exclude that 'polluted' stars are substantially younger than 'unpolluted' ones. We stress that the Be test might be the only measurement capable of distinguishing between these scenarios.

  17. New beryllium observations in low-metallicity stars

    E-Print Network [OSTI]

    P. Molaro; P. Bonifacio; F. Castelli; L. Pasquini


    We present observations of the Be II 313.0 nm resonance doublet in 14 halo and old disk stars with metallicities ranging from [Fe/H]=-0.4 to about -3.0 obtained with the CASPEC spectrograph of the ESO 3.6m telescope at a FWHM about 8.6 km/s resolution. Abundances are derived by means of the synthetic spectra technique employing Kurucz (1993) atmospheric models, with enhanced alpha-elements and no overshooting. The derived abundances together with those available in literature show that for -2.7 < [Fe/H] < -0.8 Be correlates linearly with iron [Be] proportional to 1.07(+/- 0.08)[Fe/H], giving strength to previous results. However, a steeper correlation is still possible at metallicities lower than [Fe/H]<-1.4 with [Be] proportional to 1.6(+/- 0.44)[Fe/H]. When iron is replaced with oxygen, Be is found tracking closely oxygen up to solar values, without signs of breaking in correspondence of the onset of the Galactic disk. No evidence of intrinsic dispersion is found, ought to the large errors involved in the Be abundance determinations, but for three stars (HD 106516, HD 3795, HD 211998) a significant upper limit in the Be abundance can be placed at about 1 dex below the mean trend of the Be-Fe relation. For such stars non conventional mixing is required to explain Be depletion. Be observations can be used to discriminate strongly Li-depleted stars. These are the stars which show less Li than that expected by high energy cosmic rays production as deduced from Be observations. The available Be observations imply that some of the stars which contribute to the scatter in the Li-Fe diagramme are Li-depleted stars.

  18. Chemical Evolution of Odd Elements in an Inhomogeneous Early Galaxy

    E-Print Network [OSTI]

    Takuji Tsujimoto; Toshikazu Shigeyama; Yuzuru Yoshii


    We investigate the chemical evolution of odd-numbered elements such as sodium (Na) and aluminum (Al) during the early epochs of the Galactic halo with the use of a model that reproduces the observed box-shaped distribution of extremely metal-poor stars in the [Na, Al/Mg] versus [Mg/H] plane. Our model is constructed under the assumptions that those stars retain the elemental abundance patterns produced by individual Type II supernovae (SNe), and that the yields of the odd elements depend on the initial metallicity, z, of their SN progenitors. As a result, recent abundance determinations that clarify how the [Na, Al/Mg] ratios of field stars have evolved to the solar values enable us to deduce how the yields of these odd elements depend on z. The observed trends in these abundances, in particular the very large scatter (over 1 dex in [Al/Mg]) requires that the Al yield scales as m_Al proportional to z^0.6 for [Mg/H]-1.8. It is found that the predicted frequency distribution of stars in the [Na/Mg] versus [Mg/H] diagram is very sensitive to the assumed form of the primordial IMF, and that its slope is steeper than the Salpeter IMF. The necessity to match the observed abundance patterns of odd elements and the frequency distribution of extremely metal-poor stars should provide useful constraints on nucleosynthesis calculations of metal-free massive stars as well as on theories of their formation.

  19. Beryllium in the Hyades F and G Dwarfs from Keck/HIRES Spectra

    E-Print Network [OSTI]

    Ann Merchant Boesgaard; Jeremy R. King


    Beryllium is not destroyed as easily as Li, so the abundances of Li and Be together can tell us more about the internal physical processes in stars than either element can alone. We have obtained high-resolution (45,000) and high signal-to-noise (typically 90 per pixel) spectra of the Be II resonance lines in 34 Hyades F and G dwarfs with the Keck I telescope and HIRES. The Be abundances have been derived with the spectrum synthesis method. We find that Be is depleted in the Li gap in the F stars reaching down to values of A(Be) = 0.60, or a factor of nearly seven below the meteoritic Be abundance. There is little or no depletion of Be in stars cooler than 6000 K, in spite of the large depletions (0.5 - 2.5 dex) in Li. The mean value of A(Be) for the ten coolest stars is 1.33 +/- 0.06, not far from the meteoritic value of 1.42. The pattern in the Be abundances - a Be dip in the F stars and undepleted Be in the cool stars - is well matched by the predictions of slow mixing due to stellar rotation (e.g. Deliyannis and Pinsonneault). The depletions of Li and Be probably occur simultaneously. The Li and Be abundances are correlated for stars in the temperature range of 5850 - 6680 K, similar to results from earlier work on Li and Be in F and G field stars. The Hyades G dwarfs have more Be than the sun; their initial Be may have been larger or they may not be old enough to have depleted Be. For those Hyades stars which appear to have little or no depletion of Li or Be, the Li/Be ratio is found to be 75 +/- 30. (abridged)

  20. Stochastic chemical enrichment in metal-poor systems II. Abundance ratios and scatter

    E-Print Network [OSTI]

    T. Karlsson; B. Gustafsson


    A stochastic model of the chemical enrichment of metal-poor systems by core-collapse supernovae is used to study the scatter in stellar abundance ratios. The resulting scatter in abundance ratios, e.g. as functions of the overall metallicity, is demonstrated to be crucially dependent on the as yet uncertain supernovae yields. The observed abundance ratios and their scatters therefore have diagnostic power as regards the yields. The relatively small star-to-star scatter observed in many chemical abundance ratios, e.g. by Cayrel et al. (2004) for stars down to [Fe/H] = -4, is tentatively explained by the averaging of a large number of contributing supernovae and by the cosmic selection effects favoring contributions from supernovae in a certain mass range for the most metal-poor stars. The scatter in observed abundances of alpha-elements is understood in terms of observational errors only, while additional spread in yields or sites of nucleosynthesis may affect the odd-even elements Na and Al. For the iron-group elements we find systematically too high predicted Cr/Fe and Cr/Mg ratios, as well as differences between the different sets of yields, both in terms of predicted abundance ratios and scatter. The semi-empirical yields recently suggested by Francois et al. (2004) are found to lead to scatter in abundance ratios significantly greater than observed, when applied in the inhomogeneous models. "Spurs", very narrow sequences in abundance-ratio diagrams, may disclose a single-supernova origin of the elements of the stars on the sequence. Verification of the existence of such features, called single supernova sequences (SSSs), is challenging. This will require samples of several hundred stars with abundance ratios observed to accuracies of 0.05 dex or better.


    SciTech Connect (OSTI)

    Lepine, Sebastien; Wilde, Matthew; Rojas-Ayala, Barbara; Cruz, Kelle L. [Department of Astrophysics, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); Hilton, Eric J.; Mann, Andrew W. [Institute for Astrophysics, University of Hawaii, Honolulu, HI 96822 (United States); Gaidos, Eric, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail: [Department of Geology and Geophysics, University of Hawaii, 1680 East-West Road, Honolulu, HI 96822 (United States)


    We present a spectroscopic catalog of the 1564 brightest (J < 9) M dwarf candidates in the northern sky, as selected from the SUPERBLINK proper motion catalog. Observations confirm 1408 of the candidates to be late-K and M dwarfs with spectral subtypes K7-M6. From the low ({mu} > 40 mas yr{sup -1}) proper motion limit and high level of completeness of the SUPERBLINK catalog in that magnitude range, we estimate that our spectroscopic census most likely includes >90% of all existing, northern-sky M dwarfs with apparent magnitude J < 9. Only 682 stars in our sample are listed in the Third Catalog of Nearby Stars (CNS3); most others are relative unknowns and have spectroscopic data presented here for the first time. Spectral subtypes are assigned based on spectral index measurements of CaH and TiO molecular bands; a comparison of spectra from the same stars obtained at different observatories, however, reveals that spectral band index measurements are dependent on spectral resolution, spectrophotometric calibration, and other instrumental factors. As a result, we find that a consistent classification scheme requires that spectral indices be calibrated and corrected for each observatory/instrument used. After systematic corrections and a recalibration of the subtype-index relationships for the CaH2, CaH3, TiO5, and TiO6 spectral indices, we find that we can consistently and reliably classify all our stars to a half-subtype precision. The use of corrected spectral indices further requires us to recalibrate the {zeta} parameter, a metallicity indicator based on the ratio of TiO and CaH optical bandheads. However, we find that our {zeta} values are not sensitive enough to diagnose metallicity variations in dwarfs of subtypes M2 and earlier ({+-}0.5 dex accuracy) and are only marginally useful at later M3-M5 subtypes ({+-}0.2 dex accuracy). Fits of our spectra to the Phoenix atmospheric model grid are used to estimate effective temperatures. These suggest the existence of a plateau in the M1-M3 subtype range, in agreement with model fits of infrared spectra but at odds with photometric determinations of T{sub eff}. Existing geometric parallax measurements are extracted from the literature for 624 stars, and are used to determine spectroscopic and photometric distances for all the other stars. Active dwarfs are identified from measurements of H{alpha} equivalent widths, and we find a strong correlation between H{alpha} emission in M dwarfs and detected X-ray emission from ROSAT and/or a large UV excess in the GALEX point source catalog. We combine proper motion data and photometric distances to evaluate the (U, V, W) distribution in velocity space, which is found to correlate tightly with the velocity distribution of G dwarfs in the solar neighborhood. However, active stars show a smaller dispersion in their space velocities, which is consistent with those stars being younger on average. Our catalog will be most useful to guide the selection of the best M dwarf targets for exoplanet searches, in particular those using high-precision radial velocity measurements.

  2. Origin of the Metallicity Dependence of Exoplanet Host Stars in the Protoplanetary Disk Mass Distribution

    E-Print Network [OSTI]

    M. C. Wyatt; C. J. Clarke; J. S. Greaves


    The probability of a star hosting a planet that is detectable in radial velocity surveys increases Ppl(Z) oc 10^2Z, where Z is metallicity. Core accretion models reproduce this trend, since the protoplanetary disk of a high metallicity star has a high density of solids and so forms cores which accrete gas before the primordial gas disk dissipates. This paper considers the origin of the form of Ppl(Z). We introduce a simple model in which detectable planets form when the mass of solids in the protoplanetary disk, Ms, exceeds a critical value. In this model the form of Ppl(Z) is a direct reflection of the distribution of protoplanetary disk masses, Mg, and the observed Ppl(Z) is reproduced if P(Mg>Mg') oc 1/Mg'^2. We argue that a protoplanetary disk's sub-mm dust mass is a pristine indicator of the mass available for planet-building and find the observed sub-mm disk mass distribution is consistent with the observed Ppl(Z) if Ms>0.5M_J is required to form detectable planets. Any planet formation model which imposes a critical solid mass for planet formation would reproduce the observed Ppl(Z), and core accretion models are empirically consistent with a threshold criterion. We identify 7 protoplanetary disks which, by rigid application of this criterion, would be expected to form detectable planets. A testable prediction is that Ppl(Z) should flatten both for Z>0.5dex and as more distant and lower mass planets are discovered. Further, combining this model with one in which the evolution of a star's debris disk is also influenced by the solid mass in its protoplanetary disk, results in the prediction that debris disks detected around stars with planets should be more infrared luminous than those around stars without planets in tentative agreement with recent observations.

  3. The Connection between Galaxies and Dark Matter Structures in the Local Universe

    SciTech Connect (OSTI)

    Reddick, Rachel M.; Wechsler, Risa H.; Tinker, Jeremy L.; Behroozi, Peter S.


    We provide new constraints on the connection between galaxies in the local Universe, identified by the Sloan Digital Sky Survey (SDSS), and dark matter halos and their constituent substructures in the {Lambda}CDM model using WMAP7 cosmological parameters. Predictions for the abundance and clustering properties of dark matter halos, and the relationship between dark matter hosts and substructures, are based on a high-resolution cosmological simulation, the Bolshoi simulation. We associate galaxies with dark matter halos and subhalos using subhalo abundance matching, and perform a comprehensive analysis which investigates the underlying assumptions of this technique including (a) which halo property is most closely associated with galaxy stellar masses and luminosities, (b) how much scatter is in this relationship, and (c) how much subhalos can be stripped before their galaxies are destroyed. The models are jointly constrained by new measurements of the projected two-point galaxy clustering and the observed conditional stellar mass function of galaxies in groups. We find that an abundance matching model that associates galaxies with the peak circular velocity of their halos is in good agreement with the data, when scatter of 0.20 {+-} 0.03 dex in stellar mass at a given peak velocity is included. This confirms the theoretical expectation that the stellar mass of galaxies is tightly correlated with the potential wells of their dark matter halos before they are impacted by larger structures. The data put tight constraints on the satellite fraction of galaxies as a function of galaxy stellar mass and on the scatter between halo and galaxy properties, and rule out several alternative abundance matching models that have been considered. This will yield important constraints for galaxy formation models, and also provides encouraging indications that the galaxy - halo connection can be modeled with sufficient fidelity for future precision studies of the dark Universe.

  4. DOI: 10.1007/s00340-008-2998-2 Appl. Phys. B 91, 343348 (2008)

    E-Print Network [OSTI]

    Arie, Ady


    - ric lithium niobate (SLN). Although there are several works on the refractive in- dex properties of Mg-phase-matched nonlinear interactions with these two crystal compositions in the near and mid- infrared. The results show.70.Mp 1 Introduction Periodically poled lithium niobate (PPLN) has been used in a wide variety

  5. 5. konferenca DAES Sodobni izzivi menedzmenta v agrozivilstvu. Pivola, 18.-19. mar. 2010, s. 29-37.

    E-Print Network [OSTI]

    Bohanec, Marko

    of genetically- modified organisms (GMO) for food and feed. In three 5th and 6th Framework Programme European IN DECISION SUPPORT ON GENETICALLY MODIFIED ORGANISMS ABSTRACT In the paper we present applications, qualitative multi-attribute models, DEX method, genetically modified organisms, ecological and economic

  6. Prospecting in ultracool dwarfs: measuring the metallicities of mid- and late-M dwarfs

    SciTech Connect (OSTI)

    Mann, Andrew W. [Department of Astronomy, University of Texas at Austin, TX (United States); Deacon, Niall R. [Max Planck Institute for Astronomy, Konigstuhl 17, Heidelberg D-69117 (Germany); Gaidos, Eric [Department of Geology and Geophysics, University of Hawai'i, 1680 East-West Road, Honolulu, HI 96822 (United States); Ansdell, Megan; Liu, Michael C.; Magnier, Eugene A.; Aller, Kimberly M. [Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Brewer, John M. [Department of Astronomy, Yale University, New Haven, CT 06511 (United States)


    Metallicity is a fundamental parameter that contributes to the physical characteristics of a star. The low temperatures and complex molecules present in M dwarf atmospheres make it difficult to measure their metallicities using techniques that have been commonly used for Sun-like stars. Although there has been significant progress in developing empirical methods to measure M dwarf metallicities over the last few years, these techniques have been developed primarily for early- to mid-M dwarfs. We present a method to measure the metallicity of mid- to late-M dwarfs from moderate resolution (R ? 2000) K-band (? 2.2 ?m) spectra. We calibrate our formula using 44 wide binaries containing an F, G, K, or early-M primary of known metallicity and a mid- to late-M dwarf companion. We show that similar features and techniques used for early-M dwarfs are still effective for late-M dwarfs. Our revised calibration is accurate to ?0.07 dex for M4.5-M9.5 dwarfs with 0.58 < [Fe/H] < +0.56 and shows no systematic trends with spectral type, metallicity, or the method used to determine the primary star metallicity. We show that our method gives consistent metallicities for the components of M+M wide binaries. We verify that our new formula works for unresolved binaries by combining spectra of single stars. Lastly, we show that our calibration gives consistent metallicities with the Mann et al. study for overlapping (M4-M5) stars, establishing that the two calibrations can be used in combination to determine metallicities across the entire M dwarf sequence.

  7. Journal of Cellular Biochemistry 90:109120 (2003) Fluorescence Activated Cell Sorting Reveals

    E-Print Network [OSTI]

    Zandstra, Peter W.

    of CFU-F (fibroblast) colonies that formed in vehicle versus dex. Finally, both cell autonomous and cell Heterogeneous and Cell Non-Autonomous Osteoprogenitor Differentiation in Fetal Rat Calvaria Cell Populations non-autonomous (i.e., inhibitory/stimulatory effects of cell neighbors) differentiation of osteo

  8. Impact of oxygenates on petroleum refining

    SciTech Connect (OSTI)

    Unzelman, G.H. [HyOx Inc., Fallbrook, CA (United States)


    The concept of an oxygenate, primarily ethanol, as motor fuel or as a blending agent with gasoline has been around for a long time. The idea started with the development of the internal combustion engine. Experiments in Germany almost 100 years ago. The inventor of the four-stroke-cycle combustion engine, Nikolaus Otto, originally recommended ethyl alcohol as fuel. So did Henry Ford early in his career as an automobile manufacturer. However, gasoline was readily available from crude oil at a time when the kerosene market was fading. Since it was the lowest-cost approach to satisfy a growing market, the idea of alcohol as a primary fuel was set aside. Early gasoline was simply distilled from the {open_quotes}top of the barrel.{close_quotes} While it was satisfactory for the {open_quotes}horseless carriage,{close_quotes} quality was insufficient for innovations such as higher-compression engines. Knock became a serious problem, which prompted research and the discovery of tetraethyllead as an octane improver. Had this event not taken place, the alcohols probably would have been alternatives to solve the antiknock dilemma. Instead, it took another 60 years for the octane value of alcohols and ethers to resurface and exert a commercial impact on gasoline.

  9. Construction For more information:

    E-Print Network [OSTI]

    to accommodate over 600 students; Natural Sciences living/learning community. Eddy Hall Revitalization Projected offices; Student Success Center. Faculty and students work in teams focused on energy, health; updated programming space; expanded DEX to-go venue. LEARN Student Recreation Center Completed: August

  10. Supervised Probabilistic Principal Component Analysis Shipeng Yu1,2

    E-Print Network [OSTI]

    Tresp, Volker

    Siemens AG, Corporate Technology, Information and Communications, Munich, Germany 3 MPI for Biological Cybernetics, T¨ubingen, Germany,,, kriegel transformation or document in- dexing, is of great importance and has been extensively stud- Permission to make

  11. Supervised Probabilistic Principal Component Analysis Shipeng Yu1,2

    E-Print Network [OSTI]

    Kriegel, Hans-Peter

    Siemens AG, Corporate Technology, Information and Communications, Munich, Germany 3 MPI for Biological Cybernetics, T¨ubingen, Germany,,, kriegel-59593-339-5/06/0008 ...$5.00. which is also called feature transformation or document in- dexing, is of great importance

  12. AHAM: A Dexterbased Reference Model for Adaptive Paul De Bra \\Lambda , GeertJan Houben y and Hongjing Wu

    E-Print Network [OSTI]

    De Bra, Paul

    AHAM: A Dexterbased Reference Model for Adaptive Hypermedia Paul De Bra \\Lambda , GeertJan Houben, called AHAM, which encompasses most features supported by adaptive systems that exist today in order to be able to explain AHAM rather than formally specify it. AHAM augments Dex ter with features

  13. Adaptation and Search: from Dexter and AHAM to GAF Evgeny Knutov

    E-Print Network [OSTI]

    De Bra, Paul

    Adaptation and Search: from Dexter and AHAM to GAF Evgeny Knutov Dep. of Computer Science Eindhoven, Human Factors 1. INTRODUCTION Since the most cited Adaptive Hypermedia (AH) model AHAM [1] (in 1999) new the evolution of Hypertext/Hypermedia modelling from Dex- ter Model through AHAM to the proposed GAF (Generic


    SciTech Connect (OSTI)

    Kelly, Patrick L.; Filippenko, Alexei V.; Fox, Ori D.; Zheng Weikang; Clubb, Kelsey I., E-mail: [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)


    GRB 130702A is a nearby long-duration gamma-ray burst (LGRB) discovered by the Fermi satellite whose associated afterglow was detected by the Palomar Transient Factory. Subsequent photometric and spectroscopic monitoring has identified a coincident broad-lined Type Ic supernova (SN), and nebular emission detected near the explosion site is consistent with a redshift of z = 0.145. The SN-GRB exploded at an offset of {approx}7.''6 from the center of an inclined r = 18.1 mag red disk-dominated galaxy, and {approx}0.''6 from the center of a much fainter r = 23 mag object. We obtained Keck-II DEIMOS spectra of the two objects and find a 2{sigma} upper limit on their line-of-sight velocity offset of {approx}<60 km s{sup -1}. If we calculate the inclination angle of the massive red galaxy from its axis ratio and assume that its light is dominated by a very thin disk, the explosion would have a {approx}60 kpc central offset, or {approx}9 times the galaxy's half-light radius. A significant bulge or a thicker disk would imply a higher inclination angle and greater central offset. The substantial offset suggests that the faint source is a separate dwarf galaxy. The star-formation rate of the dwarf galaxy is {approx}0.05 M{sub Sun} yr{sup -1}, and we place an upper limit on its oxygen abundance of 12 + log(O/H) < 8.16 dex. The identification of an LGRB in a dwarf satellite of a massive, metal-rich primary galaxy suggests that recent detections of LGRBs spatially coincident with metal-rich galaxies may be, in some cases, superpositions.


    SciTech Connect (OSTI)

    Smith, Verne V.; Cunha, Katia [National Optical Astronomy Observatories, Tucson, AZ 85719 (United States)] [National Optical Astronomy Observatories, Tucson, AZ 85719 (United States); Shetrone, Matthew D. [Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712 (United States)] [Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Meszaros, Szabolcs; Allende Prieto, Carlos [Instituto d'Astrofisica de Canarias, E-38205, La Laguna, Tenerife (Spain)] [Instituto d'Astrofisica de Canarias, E-38205, La Laguna, Tenerife (Spain); Bizyaev, Dmitry [Apache Point Observatory, Sunspot, NM 88349 (United States)] [Apache Point Observatory, Sunspot, NM 88349 (United States); Garcia Perez, Ana; Majewski, Steven R. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States)] [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States); Schiavon, Ricardo [Astrophysics Research Institute, Liverpool John Moores University, Liverpool L3 5UX (United Kingdom)] [Astrophysics Research Institute, Liverpool John Moores University, Liverpool L3 5UX (United Kingdom); Holtzman, Jon [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States)] [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States); Johnson, Jennifer A., E-mail: [Department of Astronomy, Ohio State University, Columbus, OH 43210 (United States)


    High-resolution H-band spectra of five bright field K, M, and MS giants, obtained from the archives of the Kitt Peak National Observatory Fourier transform spectrometer, are analyzed to determine chemical abundances of 16 elements. The abundances were derived via spectrum synthesis using the detailed linelist prepared for the Sloan Digital Sky Survey III Apache Point Galactic Evolution Experiment (APOGEE), which is a high-resolution near-infrared spectroscopic survey to derive detailed chemical abundance distributions and precise radial velocities for 100,000 red giants sampling all Galactic stellar populations. The red giant sample studied here was chosen to probe which chemical elements can be derived reliably from the H-band APOGEE spectral region. These red giants consist of two K-giants ({alpha} Boo and {mu} Leo), two M-giants ({beta} And and {delta} Oph), and one thermally pulsing asymptotic giant branch (TP-AGB) star of spectral type MS (HD 199799). Measured chemical abundances include the cosmochemically important isotopes {sup 12}C, {sup 13}C, {sup 14}N, and {sup 16}O, along with Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. The K and M giants exhibit the abundance signature of the first dredge-up of CN-cycle material, while the TP-AGB star shows clear evidence of the addition of {sup 12}C synthesized during {sup 4}He-burning thermal pulses and subsequent third dredge-up. A comparison of the abundances derived here with published values for these stars reveals consistent results to {approx}0.1 dex. The APOGEE spectral region and linelist is thus well suited for probing both Galactic chemical evolution, as well as internal nucleosynthesis and mixing in populations of red giants via high-resolution spectroscopy.


    SciTech Connect (OSTI)

    Hamano, Satoshi; Kobayashi, Naoto [Institute of Astronomy, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Kondo, Sohei [Koyama Astronomical Observatory, Kyoto-Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto 603-8555 (Japan); Tsujimoto, Takuji [National Astronomical Observatory of Japan and Department of Astronomical Science, Graduate University for Advanced Studies, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Okoshi, Katsuya [Faculty of Industrial Science and Technology, Tokyo University of Science, 102-1 Tomino, Oshamanbe, Hokkaido 049-3514 (Japan); Shigeyama, Toshikazu, E-mail: [Research Center for the Early Universe, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan)


    Using the Subaru 8.2 m Telescope with the IRCS Echelle spectrograph, we obtained high-resolution (R = 10,000) near-infrared (1.01-1.38 {mu}m) spectra of images A and B of the gravitationally lensed QSO B1422+231 (z = 3.628) consisting of four known lensed images. We detected Mg II absorption lines at z = 3.54, which show a large variance of column densities ({approx}0.3 dex) and velocities ({approx}10 km s{sup -1}) between sightlines A and B with a projected separation of only 8.4h{sup -1}{sub 70} pc at that redshift. This is the smallest spatial structure of the high-z gas clouds ever detected after Rauch et al. found a 20 pc scale structure for the same z = 3.54 absorption system using optical spectra of images A and C. The observed systematic variances imply that the system is an expanding shell as originally suggested by Rauch et al. By combining the data for three sightlines, we managed to constrain the radius and expansion velocity of the shell ({approx}50-100 pc, 130 km s{sup -1}), concluding that the shell is truly a supernova remnant (SNR) rather than other types of shell objects, such as a giant H II region. We also detected strong Fe II absorption lines for this system, but with much broader Doppler width than that of {alpha}-element lines. We suggest that this Fe II absorption line originates in a localized Fe II-rich gas cloud that is not completely mixed with plowed ambient interstellar gas clouds showing other {alpha}-element low-ion absorption lines. Along with the Fe richness, we conclude that the SNR is produced by an SN Ia explosion.

  17. Parallel In Situ Indexing for Data-intensive Computing

    SciTech Connect (OSTI)

    Kim, Jinoh; Abbasi, Hasan; Chacon, Luis; Docan, Ciprian; Klasky, Scott; Liu, Qing; Podhorszki, Norbert; Shoshani, Arie; Wu, Kesheng


    As computing power increases exponentially, vast amount of data is created by many scientific re- search activities. However, the bandwidth for storing the data to disks and reading the data from disks has been improving at a much slower pace. These two trends produce an ever-widening data access gap. Our work brings together two distinct technologies to address this data access issue: indexing and in situ processing. From decades of database research literature, we know that indexing is an effective way to address the data access issue, particularly for accessing relatively small fraction of data records. As data sets increase in sizes, more and more analysts need to use selective data access, which makes indexing an even more important for improving data access. The challenge is that most implementations of in- dexing technology are embedded in large database management systems (DBMS), but most scientific datasets are not managed by any DBMS. In this work, we choose to include indexes with the scientific data instead of requiring the data to be loaded into a DBMS. We use compressed bitmap indexes from the FastBit software which are known to be highly effective for query-intensive workloads common to scientific data analysis. To use the indexes, we need to build them first. The index building procedure needs to access the whole data set and may also require a significant amount of compute time. In this work, we adapt the in situ processing technology to generate the indexes, thus removing the need of read- ing data from disks and to build indexes in parallel. The in situ data processing system used is ADIOS, a middleware for high-performance I/O. Our experimental results show that the indexes can improve the data access time up to 200 times depending on the fraction of data selected, and using in situ data processing system can effectively reduce the time needed to create the indexes, up to 10 times with our in situ technique when using identical parallel settings.


    SciTech Connect (OSTI)

    Kravtsov, V. V. [Instituto de AstronomIa, Universidad Catolica del Norte, Avenida Angamos 0610, Casilla 1280, Antofagasta (Chile)], E-mail:


    This paper aims at demonstrating, for the first time, very probable universal peculiarities of the evolution of stars in the lower red giant branch (RGB) of Galactic globular clusters (GCs), reflected in two corresponding dips in the luminosity functions (LFs). By relying on the database of Hubble Space Telescope photometry of GCs, we analyze the lower RGB LFs of a sample of 18 GCs in a wide metallicity range, {delta}[Fe/H] {approx} 1.9 dex. We first show that in the F555W-(F439W-F555W) color-magnitude diagrams (CMDs), the lower RGB of GCs, except for the most metal-poor of them, frequently shows an apparent 'knee'. It reveals itself as a fairly abrupt change of the RGB slope. At the same luminosity level, the RGB LFs show a feature in the form of a more or less pronounced dip. We find that the magnitude difference between the RGB base and the given feature is, on average, around {delta} F555W{sup dip} {sub base}{approx} 1.4 mag. It shows a marginal variation with metallicity, if any, comparable to the error. At the same time, the magnitude difference between the dip and the RGB bump, {delta} F555W{sup bump} {sub dip}, decreases with increasing metallicity and falls within the range 0.8 {approx}< {delta} F555W{sup bump} {sub dip} {approx}< 1.7 mag. Generalized LFs (GLFs) have been obtained for three subsamples of GCs within limited metallicity ranges and with different horizontal branch (HB) morphology. They reproduce the 'knee-related' dip that is statistically significant in two of the GLFs. This feature turns out to be more pronounced in the GLFs of GCs with either the blue or red HB morphology than with the intermediate one. The same GLFs also reveal an additional probable universal dip. It shows up below the RGB bump at {delta} F555W slightly increasing from {approx}0.3 to {approx}0.5 mag with increasing metallicity. Also, the statistical significance of this 'prebump' dip increases, on average, toward higher metallicity. Except for the well known RGB bump, no other universal features corresponding to those found here were so far empirically revealed or theoretically predicted in the lower RGB of GCs.

  19. Accurate Gravities of F, G, and K stars from High Resolution Spectra Without External Constraints

    E-Print Network [OSTI]

    Brewer, John M; Basu, Sarbani; Valenti, Jeff A; Piskunov, Nikolai


    We demonstrate a new procedure to derive accurate and precise surface gravities from high resolution spectra without the use of external constraints. Our analysis utilizes Spectroscopy Made Easy (SME) with robust spectral line constraints and uses an iterative process to mitigate degeneracies in the fitting process. We adopt an updated radiative transfer code, a new treatment for neutral perturber broadening, a line list with multiple gravity constraints and separate fitting for global stellar properties and abundance determinations. To investigate the sources of temperature dependent trends in determining log g noted in previous studies, we obtained Keck HIRES spectra of 42 Kepler asteroseismic stars. In comparison to asteroseismically determined log g our spectroscopic analysis has a constant offset of 0.01 dex with a root mean square (RMS) scatter of 0.05 dex. We also analyzed 30 spectra which had published surface gravities determined using the $a/R_*$ technique from planetary transits and found a constan...


    SciTech Connect (OSTI)

    K. Osseo-Asare; X. Zeng


    Ever-stringent environmental constraints dictate that future coal cleaning technologies be compatible with micron-size particles. This research program seeks to develop an advanced coal cleaning technology uniquely suited to micron-size particles, i.e., aqueous biphase extraction. The partitioning behaviors of hematite in the dextran (Dex)/Triton X-100 (TX100) and polyethylene glycol (PEG)/dextran systems were investigated and the effects of some ionic surfactants on solid partition were studied. In both biphase systems, the particles stayed in the bottom dextran-rich phase under all pH conditions. This behavior is attributable to the fact that the hydrophilic oxide particles prefer the more hydrophilic bottom phase. Also, the strong favorable interaction between dextran and ferric oxide facilitates the dispersion of the solids in the polysaccharide-rich phase. In the Dex/TX100 system, addition of sodium dodecylsulfate (SDS) or potassium oleate had no effect on the solid partition; on the other hand, addition of dodecyltrimethylammonium bromide (DTAB) transferred the particles to the top phase or interface at high pH values. In the PEG/Dex system, the preferred location of hematite remained the bottom phase in the presence of either SDS or DTAB. The effects of anionic surfactants on the partition behavior are attributable to the fact that they are not able to replace the strongly adsorbed polysaccharide layer on the ferric oxide surface. The results with the cationic surfactant are due to electrostatic interaction between the cationic surfactant and the charged surface of the solid particles. The difference in solids partitioning in the two systems is the result of the different distribution of DTAB in these systems. In the Dex/TX100 system, DTAB prefers the top surfactant-rich phase, while it concentrates in the bottom phase in the PEG/dextran system.

  1. M. Steffen, AIP, Sternphysik, 2002 Stellar Physics

    E-Print Network [OSTI]

    .7 dex. Fig. 1a: Snapshot from a 3D numerical simulation of solar surface convection in a Cartesian box of 5:56 #2; 5:56 #2; 2:25 Mm (140 #2; 140 #2; 150 cells), ranging from log #28; Ross #25; +5 : : : 6 in optical depth. The panel shows the emergent frequency­integrated intensity at the top face (?I rms #25; 15

  2. Novel Characterization of GDI Engine Exhaust for Gasoline and Mid-Level Gasoline-Alcohol Blends

    SciTech Connect (OSTI)

    Storey, John Morse [ORNL] [ORNL; Lewis Sr, Samuel Arthur [ORNL] [ORNL; Szybist, James P [ORNL] [ORNL; Thomas, John F [ORNL] [ORNL; Barone, Teresa L [ORNL] [ORNL; Eibl, Mary A [ORNL] [ORNL; Nafziger, Eric J [ORNL] [ORNL; Kaul, Brian C [ORNL] [ORNL


    Gasoline direct injection (GDI) engines can offer improved fuel economy and higher performance over their port fuel-injected (PFI) counterparts, and are now appearing in increasingly more U.S. and European vehicles. Small displacement, turbocharged GDI engines are replacing large displacement engines, particularly in light-duty trucks and sport utility vehicles, in order for manufacturers to meet more stringent fuel economy standards. GDI engines typically emit the most particulate matter (PM) during periods of rich operation such as start-up and acceleration, and emissions of air toxics are also more likely during this condition. A 2.0 L GDI engine was operated at lambda of 0.91 at typical loads for acceleration (2600 rpm, 8 bar BMEP) on three different fuels; an 87 anti-knock index (AKI) gasoline (E0), 30% ethanol blended with the 87 AKI fuel (E30), and 48% isobutanol blended with the 87 AKI fuel. E30 was chosen to maximize octane enhancement while minimizing ethanol-blend level and iBu48 was chosen to match the same fuel oxygen level as E30. Particle size and number, organic carbon and elemental carbon (OC/EC), soot HC speciation, and aldehydes and ketones were all analyzed during the experiment. A new method for soot HC speciation is introduced using a direct, thermal desorption/pyrolysis inlet for the gas chromatograph (GC). Results showed high levels of aromatic compounds were present in the PM, including downstream of the catalyst, and the aldehydes were dominated by the alcohol blending.

  3. Improving the Understanding of Intake and Charge Effects for Increasing RCCI Engine Efficiency

    SciTech Connect (OSTI)

    Splitter, Derek A [ORNL; Reitz, Rolf [University of Wisconsin; Wissink, martin [University of Wisconsin; DelVescovo, Dan [University of Wisconsin


    The present experimental engine efficiency study explores the effects of intake pressure and temperature, and premixed and global equivalence ratios on gross thermal efficiency (GTE) using the reactivity controlled compression ignition (RCCI) combustion strategy. Experiments were conducted in a heavy-duty single-cylinder engine at constant net load (IMEPn) of 8.45 bar, 1300 rev/min engine speed, with 0% EGR, and a 50% mass fraction burned combustion phasing (CA50) of 0.5 CA ATDC. The engine was port fueled with E85 for the low reactivity fuel and direct injected with 3.5% 2-ethylhexyl nitrate (EHN) doped into 91 anti-knock index (AKI) gasoline for the high-reactivity fuel. The resulting reactivity of the enhanced fuel corresponds to an AKI of approximately 56 and a cetane number of approximately 28. The engine was operated with a wide range of intake pressures and temperatures, and the ratio of low- to high-reactivity fuel was adjusted to maintain a fixed speed-phasing-load condition. This allowed for the investigation of several combinations of intake temperature, intake pressure, and charge stratification at otherwise constant thermodynamic conditions. The results show that sources of engine inefficiency compete as functions of premixed and global equivalence ratios. Losses are minimized through proper balancing of intake pressure and temperature, such that the global equivalence ratio ( global) is as lean as possible without overly lean regions of the stratified charge causing an increase in incomplete combustion. The explored speed-load-phasing combination shows that losses are minimized at conditions where approximately 2/3 of the fuel is fully premixed. The results exhibit a pathway for achieving simultaneous increases in combustion and fuel efficiency through proper fuel reactivity and initial condition management.

  4. ISO-SWS calibration and the accurate modelling of cool-star atmospheres: I. Method

    E-Print Network [OSTI]

    L. Decin; C. Waelkens; K. Eriksson; B. Gustafsson; B. Plez; A. J. Sauval; W. Van Assche; B. Vandenbussche


    A detailed spectroscopic study of the ISO-SWS data of the red giant Alpha Tau is presented, which enables not only the accurate determination of the stellar parameters of Alpha Tau, but also serves as a critical review of the ISO-SWS calibration. This study is situated in a broader context of an iterative process in which both accurate observations of stellar templates and cool star atmosphere models are involved to improve the ISO-SWS calibration process as well as the theoretical modelling of stellar atmospheres. Therefore a sample of cool stars, covering the whole A0 -- M8 spectral classification, has been observed in order to disentangle calibration problems and problems in generating the theoretical models and corresponding synthetic spectrum. By using stellar parameters found in the literature large discrepancies were seen between the ISO-SWS data and the generated synthetic spectrum of Alpha Tau. A study of the influence of various stellar parameters on the theoretical models and synthetic spectra, in conjunction with the Kolmogorov-Smirnov test to evaluate objectively the goodness-of-fit, enables us to pin down the stellar parameters with a high accuracy: Teff = 3850 +/- 70 K, log g = 1.50 +/- 0.15, M = 2.3 +/- 0.8 Msun, z = -0.15 +/- 0.20 dex, microturbulence = 1.7 +/- 0.3 km/s, 12C/13C= 10 +/- 1, abundance of C = 8.35 +/- 0.20 dex, abundance of N= 8.35 +/- 0.25 dex, abundance of O = 8.83 +/- 0.15 dex and the angular diameter is 20.77 +/- 0.83 mas. These atmospheric parameters were then compared with the results provided by other authors using other methods and/or spectra.

  5. A Correlation between Galaxy Light Concentration and Supermassive Black Hole Mass

    E-Print Network [OSTI]

    Alister W. Graham; Peter Erwin; Nicola Caon; Ignacio Trujillo


    We present evidence for a strong correlation between the concentration of bulges and the mass of their central supermassive black hole (M_bh) -- more concentrated bulges have more massive black holes. Using C_{r_e}(1/3) from Trujillo, Graham & Caon (2001b) as a measure of bulge concentration, we find that log (M_bh/M_sun) = 6.81(+/-0.95)C_{r_e}(1/3) + 5.03(+/-0.41). This correlation is shown to be marginally stronger (Spearman's r_s=0.91) than the relationship between the logarithm of the stellar velocity dispersion and log M_bh (Spearman's r_s=0.86), and has comparable, or less, scatter (0.31 dex in log M_bh), which decreases to 0.19 dex when we use only those galaxies whose supermassive black hole's radius of influence is resolved and remove one well understood outlying data point).

  6. A&A manuscript no. (will be inserted by hand later)

    E-Print Network [OSTI]

    Gehren, Thomas

    are approximately solar above [Fe/H] ;2:2 where they decrease rapidly by 0.5 - 0.6 dex. The direct method based offprint requests to: L. Mashonkina, e-mail: ? Based on observations at the German- citation energy of 0:7 eV) these Ba II lines can be detected even in extremely metal-poor stars. Two types

  7. Radial mixing and the transition between the thick and thin Galactic discs

    E-Print Network [OSTI]

    Misha Haywood


    The analysis of the kinematics of solar neighbourhood stars shows that the low and high metallicity tails of the thin disc are populated by objects which orbital properties suggest an origin in the outer and inner galactic disc, respectively. Signatures of radial migration are identified in various recent samples, and are shown to be responsible for the high metallicity dispersion in the age-metallicity distribution. Most importantly, it is shown that the population of low metallicity wanderers of the thin disc (-0.7disc (which terminal metallicity is about -0.2 dex). It implies that the thin disc at the solar circle has started to form stars at about this same metallicity. This is also consistent with the fact that 'transition' objects, which have alpha-element abundance intermediate between that of the thick and thin discs, are found in the range [-0.4,-0.2] dex. Once the metal-poor thin disc stars are recognised for what they are - wanderers from the outer thin disc - the parenthood between the two discs can be identified on stars genuinely formed at the solar circle through an evolutionary sequence in [alpha/Fe] and [Fe/H] . Another consequence is that stars that can be considered as truly resulting of the chemical evolution at the solar circle have a metallicity restricted to about [-0.2,+0.2] dex, confirming an old idea that most chemical evolution in the Milky Way have preceded the thin disc formation.


    SciTech Connect (OSTI)

    Sesar, Branimir; Cohen, Judith G.; Bellm, Eric C.; Levitan, David; Tang, Sumin; Waszczak, Adam; Kulkarni, Shrinivas R.; Prince, Thomas A. [Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Grillmair, Carl J.; Laher, Russ R.; Surace, Jason A. [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Bhalerao, Varun B. [Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411 007 (India); Ofek, Eran O., E-mail: [Benoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel)


    We report positions, velocities, and metallicities of 50 ab-type RR Lyrae (RRab) stars observed in the vicinity of the Orphan stellar stream. Using about 30 RRab stars classified as being likely members of the Orphan stream, we study the metallicity and the spatial extent of the stream. We find that RRab stars in the Orphan stream have a wide range of metallicities, from 1.5 dex to 2.7 dex. The average metallicity of the stream is 2.1 dex, identical to the value obtained by Newberg et al. using blue horizontal branch stars. We find that the most distant parts of the stream (40-50 kpc from the Sun) are about 0.3 dex more metal-poor than the closer parts (within ?30 kpc), suggesting a possible metallicity gradient along the stream's length. We have extended the previous studies and have mapped the stream up to 55 kpc from the Sun. Even after a careful search, we did not identify any more distant RRab stars that could plausibly be members of the Orphan stream. If confirmed with other tracers, this result would indicate a detection of the end of the leading arm of the stream. We have compared the distances of Orphan stream RRab stars with the best-fit orbits obtained by Newberg et al. We find that model 6 of Newberg et al. cannot explain the distances of the most remote Orphan stream RRab stars, and conclude that the best fit to distances of Orphan stream RRab stars and to the local circular velocity is provided by potentials where the total mass of the Galaxy within 60 kpc is M{sub 60} ? 2.7 10{sup 11} M{sub ?}, or about 60% of the mass found by previous studies. More extensive modeling that would consider non-spherical potentials and the possibility of misalignment between the stream and the orbit is highly encouraged.

  9. Identification of metal-poor stars using the artificial neural network

    E-Print Network [OSTI]

    Giridhar, Sunetra; Kunder, Andrea; Muneer, S; Selvakumar, G


    Identification of metal-poor stars among field stars is extremely useful for studying the structure and evolution of the Galaxy and of external galaxies. We search for metal-poor stars using the artificial neural network (ANN) and extend its usage to determine absolute magnitudes. We have constructed a library of 167 medium-resolution stellar spectra (R ~ 1200) covering the stellar temperature range of 4200 to 8000 K, log g range of 0.5 to 5.0, and [Fe/H] range of -3.0 to +0.3 dex. This empirical spectral library was used to train ANNs, yielding an accuracy of 0.3 dex in [Fe/H], 200 K in temperature, and 0.3 dex in log g. We found that the independent calibrations of near-solar metallicity stars and metal-poor stars decreases the errors in T_eff and log g by nearly a factor of two. We calculated T_eff, log g, and [Fe/H] on a consistent scale for a large number of field stars and candidate metal-poor stars. We extended the application of this method to the calibration of absolute magnitudes using nearby stars ...

  10. The Relation between Dynamical Mass-to-Light Ratio and Color for Massive Quiescent Galaxies out to z~2 and Comparison with Stellar Population Synthesis Models

    E-Print Network [OSTI]

    van de Sande, Jesse; Franx, Marijn; Bezanson, Rachel; van Dokkum, Pieter G


    We explore the relation between the dynamical mass-to-light ratio ($M/L$) and rest-frame color of massive quiescent galaxies out to z~2. We use a galaxy sample with measured stellar velocity dispersions in combination with Hubble Space Telescope and ground-based multi-band photometry. Our sample spans a large range in $\\log M_{dyn}/L_{g}$ (of 1.6~dex) and $\\log M_{dyn}/L_{K}$ (of 1.3~dex). There is a strong, approximately linear correlation between the $M/L$ for different wavebands and rest-frame color. The root-mean-scatter scatter in $\\log~M_{dyn}/L$ residuals implies that it is possible to estimate the $M/L$ with an accuracy of ~0.25 dex from a single rest-frame optical color. Stellar population synthesis (SPS) models with a Salpeter stellar initial mass function (IMF) can not simultaneously match $M_{dyn}/L_{g}$ vs. $(g-z)_{rest-frame}$ and $M_{dyn}/L_{K}$ vs. $(g-K)_{rest-frame}$. By changing the slope of the IMF we are still unable to explain the M/L of the bluest and reddest galaxies. We find that an I...


    SciTech Connect (OSTI)

    Kartaltepe, Jeyhan S.; Sanders, D. B.; Le Floc'h, E.; Ilbert, O. [Institute for Astronomy, 2680 Woodlawn Drive, University of Hawaii, Honolulu, HI 96822 (United States); Frayer, D. T. [Infrared Processing and Analysis Center, California Institute of Technology 100-22, Pasadena, CA 91125 (United States); Aussel, H. [CNRS, AIM-Unite Mixte de Recherche CEA-CNRS-Universite Paris VII-UMR 7158, F-91191 Gif-sur-Yvette (France); Arnouts, S. [Canada-France-Hawaii Telescope Corporation, 65-1238 Mamalahoa Hwy, Kamuela, HI 96743 (United States); Salvato, M.; Scoville, N. Z.; Capak, P. [California Institute of Technology, MC 105-24, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Surace, J.; Yan, L. [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Brusa, M.; Hasinger, G. [Max Planck Institut fuer Extraterrestrische Physik, D-85478 Garching (Germany); Caputi, K.; Carollo, C. M. [Department of Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Civano, F.; Elvis, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Faure, C. [Laboratoire d'Astrophysique, Ecole Polytechnique Federale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix (Switzerland); Koekemoer, A. M., E-mail: jeyhan@ifa.hawaii.ed, E-mail: jeyhan@noao.ed [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)


    We present a large robust sample of 1503 reliable and unconfused 70 mum selected sources from the multiwavelength data set of the Cosmic Evolution Survey. Using the Spitzer IRAC and MIPS photometry, we estimate the total infrared (IR) luminosity, L{sub IR} (8-1000 mum), by finding the best-fit template from several different template libraries. The long-wavelength 70 and 160 mum data allow us to obtain a reliable estimate of L{sub IR}, accurate to within 0.2 and 0.05 dex, respectively. The 70 mum data point enables a significant improvement over the luminosity estimates possible with only a 24 mum detection. The full sample spans a wide range in IR luminosity, L{sub IR} approx 10{sup 8}-10{sup 14} L{sub sun}, with a median luminosity of 10{sup 11.4} L{sub sun}. We identify a total of 687 luminous, 303 ultraluminous, and 31 hyperluminous infrared galaxies (LIRGs, ULIRGs, and HyLIRGs) over the redshift range 0.01 < z < 3.5 with a median redshift of 0.5. Presented here are the full spectral energy distributions (SEDs) for each of the sources compiled from the extensive multiwavelength data set from the ultraviolet (UV) to the far-infrared. A catalog of the general properties of the sample (including the photometry, redshifts, and L{sub IR}) is included with this paper. We find that the overall shape of the SED and trends with L{sub IR} (e.g., IR color temperatures and optical-IR ratios) are similar to what has been seen in studies of local objects; however, our large sample allows us to see the extreme spread in UV to near-infrared colors spanning nearly 3 orders of magnitude. In addition, using SED fits we find possible evidence for a subset of cooler ultraluminous objects than observed locally. However, until direct observations at longer wavelengths are obtained, the peak of emission and the dust temperature cannot be well constrained. We use these SEDs, along with the deep radio and X-ray coverage of the field, to identify a large sample of candidate active galactic nuclei (AGNs). We find that the fraction of AGNs increases strongly with L{sub IR}, as it does in the local universe, and that nearly 70% of ULIRGs and all HyLIRGs likely host a powerful AGN.

  12. Dark Matter and Stellar Mass in the Luminous Regions of Disk Galaxies

    E-Print Network [OSTI]

    Pizagno, J; Weinberg, D H; Rix, H W; Harbeck, D; Grebel, E K; Bell, E; Brinkmann, J; Holtzman, J; West, A; Pizagno, James; Prada, Francisco; Weinberg, David H.; Rix, Hans-Walter; Harbek, Daniel; Grebel, Eva K.; Bell, Eric; Brinkmann, Jon; Holtzman, Jon; West, Andrew


    We investigate the correlations among stellar mass (M_*), disk scale length (R_d), and rotation velocity at 2.2 disk scale lengths (V_2.2) for a sample of 81 disk-dominated galaxies (disk/total >= 0.9) selected from the SDSS. We measure V_2.2 from long-slit H-alpha rotation curves and infer M_* from galaxy i-band luminosities (L_i) and g-r colors. We find logarithmic slopes of 2.60+/-0.13 and 3.05+/-0.12 for the L_i-V_2.2 and M_*-V_2.2 relations, somewhat shallower than most previous studies, with intrinsic scatter of 0.13 dex and 0.16 dex. Our direct estimates of the total-to-stellar mass ratio within 2.2R_d, assuming a Kroupa IMF, yield a median ratio of 2.4 for M_*>10^10 Msun and 4.4 for M_*=10^9-10^10 Msun, with large scatter at a given M_* and R_d. The typical ratio of the rotation speed predicted for the stellar disk alone to the observed rotation speed at 2.2R_d is ~0.65. The distribution of R_d at fixed M_* is broad, but we find no correlation between disk size and the residual from the M_*-V_2.2 rela...

  13. The Absence of an Environmental Dependence in the Mass-Metallicity Relation at z=2

    E-Print Network [OSTI]

    Kacprzak, Glenn G; Nanayakkara, Themiya; Kobayashi, Chiaki; Tran, Kim-Vy H; Kewley, Lisa J; Glazebrook, Karl; Spitler, Lee; Taylor, Philip; Cowley, Michael; Labb, Ivo; Straatman, Caroline; Tomczak, Adam


    We investigate the environmental dependence of the mass-metallicity relation at z=2 with MOSFIRE/Keck as part of the ZFIRE survey. Here, we present the chemical abundance of a Virgo-like progenitor at z=2.095 that has an established red sequence. We identified 43 cluster ($=2.095\\pm0.004$) and 74 field galaxies ($=2.195\\pm0.083$) for which we can measure metallicities. For the first time, we show that there is no discernible difference between the mass-metallicity relation of field and cluster galaxies to within 0.02dex. Both our field and cluster galaxy mass-metallicity relations are consistent with recent field galaxy studies at z~2. We present hydrodynamical simulations for which we derive mass-metallicity relations for field and cluster galaxies. We find at most a 0.1dex offset towards more metal-rich simulated cluster galaxies. Our results from both simulations and observations are suggestive that environmental effects, if present, are small and are secondary to the ongoing inflow and outflow processes t...


    SciTech Connect (OSTI)

    Burrows, Adam; Nampaisarn, Thane [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Heng, Kevin, E-mail:, E-mail:, E-mail: [Institute for Advanced Study, School of Natural Sciences, 1 Einstein Drive, Princeton, NJ 08540 (United States)


    Employing realistic and consistent atmosphere boundary conditions, we have generated evolutionary models for brown dwarfs and very low mass stars (VLMs) for different atmospheric metallicities ([Fe/H]), with and without clouds. We find that the spread in radius at a given mass and age can be as large as {approx}10% to {approx}25%, with higher-metallicity, higher-cloud-thickness atmospheres resulting quite naturally in larger radii. For each 0.1 dex increase in [Fe/H], radii increase by {approx}1% to {approx}2.5%, depending upon the age and mass. We also find that, while for smaller masses and older ages brown dwarf radii decrease with increasing helium fraction (Y, as expected), for more massive brown dwarfs and a wide range of ages they increase with helium fraction. The increase in radius in going from Y = 0.25 to Y = 0.28 can be as large as {approx}0.025 R{sub J} ({approx}2.5%). Furthermore, we find that for VLMs an increase in atmospheric metallicity from 0.0 to 0.5 dex, increases radii by {approx}4%, and from -0.5 to 0.5 dex by {approx}10%. Therefore, we suggest that opacity due to higher metallicity might naturally account for the apparent radius anomalies in some eclipsing VLM systems. Ten to twenty-five percent variations in radius exceed errors stemming from uncertainties in the equation of state alone. This serves to emphasize that transit and eclipse measurements of brown dwarf radii constrain numerous effects collectively, importantly including the atmosphere and condensate cloud models, and not just the equation of state. At all times, one is testing a multi-parameter theory, and not a universal radius-mass relation.


    SciTech Connect (OSTI)

    Lee, Young Sun [Department of Astronomy, New Mexico State University, Las Cruces, NM 88003 (United States); Beers, Timothy C.; Placco, Vinicius M. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Masseron, Thomas [Institut d'Astronomie et d'Astrophysique, Universit Libre de Bruxelles, CP 226, Boulevard du Triomphe, B-1050 Bruxelles (Belgium); Plez, Bertrand [Laboratoire Univers et Particules de Montpellier, Universit Montpellier 2, CNRS, F-34095 Montpellier (France); Rockosi, Constance M. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Sobeck, Jennifer [Laboratoire Lagrange (UMR7293), Universit de Nice Sophia Antipolis, CNRS, Observatoire de la Cte d'Azur, BP 4229, F-06304 Nice Cedex 04 (France); Yanny, Brian [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Lucatello, Sara [INAF-Osservatorio Astronomico di Padova, vicolo dell'Osservatorio 5, I-35122 Padova (Italy); Sivarani, Thirupathi [Indian Institute of Astrophysics, 2nd block Koramangala, Bangalore-560034 (India); Carollo, Daniela, E-mail: [Department of Physics and Astronomy, Astronomy, Astrophysics and Astrophotonic Research Center, Macquarie University, North Ryde, NSW 2019 (Australia)


    We describe a method for the determination of stellar [C/Fe] abundance ratios using low-resolution (R = 2000) stellar spectra from the Sloan Digital Sky Survey (SDSS) and its Galactic sub-survey, the Sloan Extension for Galactic Understanding and Exploration (SEGUE). By means of a star-by-star comparison with a set of SDSS/SEGUE spectra with available estimates of [C/Fe] based on published high-resolution analyses, we demonstrate that we can measure [C/Fe] from SDSS/SEGUE spectra with S/N ? 15 {sup 1} to a precision better than 0.35 dex for stars with atmospheric parameters in the range T {sub eff} = [4400, 6700] K, log g = [1.0, 5.0], [Fe/H] = [4.0, +0.5], and [C/Fe] = [0.25, +3.5]. Using the measured carbon-to-iron abundance ratios obtained by this technique, we derive the frequency of carbon-enhanced stars ([C/Fe] ? +0.7) as a function of [Fe/H], for both the SDSS/SEGUE stars and other samples from the literature. We find that the differential frequency slowly rises from almost zero to about 14% at [Fe/H] ? 2.4, followed by a sudden increase, by about a factor of three, to 39% from [Fe/H] ? 2.4 to [Fe/H] ? 3.7. Although the number of stars known with [Fe/H] < 4.0 remains small, the frequency of carbon-enhanced metal-poor (CEMP) stars below this value is around 75%. We also examine how the cumulative frequency of CEMP stars varies across different luminosity classes. The giant sample exhibits a cumulative CEMP frequency of 32% for [Fe/H] ? 2.5, 31% for [Fe/H] ? 3.0, and 33% for [Fe/H] ? 3.5; a roughly constant value. For the main-sequence turnoff stars, we obtain a lower cumulative CEMP frequency, around 10% for [Fe/H] ? 2.5, presumably due to the difficulty of identifying CEMP stars among warmer turnoff stars with weak CH G-bands. The dwarf population displays a large change in the cumulative frequency for CEMP stars below [Fe/H] = 2.5, jumping from 15% for [Fe/H] ? 2.5 to about 75% for [Fe/H] ? 3.0. When we impose a restriction with respect to distance from the Galactic mid-plane (|Z| < 5 kpc), the frequency of the CEMP giants does not increase at low metallicity ([Fe/H] < 2.5), but rather decreases due to the dilution of C-rich material in stars that have undergone mixing with CNO-processed material from their interiors. The frequency of CEMP stars near the main-sequence turnoff, which are not expected to have experienced mixing, increases for [Fe/H] ? 3.0. The general rise in the global CEMP frequency at low metallicity is likely due to the transition from the inner-halo to the outer-halo stellar populations with declining metallicity and increasing distance from the plane.

  16. ~ 15206 Station 7 Stat io 6 A 15415 } ~ 15455 ". ~ '15405

    E-Print Network [OSTI]

    Rathbun, Julie A.



    SciTech Connect (OSTI)

    Verner, G. A.; Chaplin, W. J.; Elsworth, Y. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Basu, S. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Brown, T. M. [Las Cumbres Observatory Global Telescope, Goleta, CA 93117 (United States); Hekker, S. [Astronomical Institute, 'Anton Pannekoek', University of Amsterdam, P.O. Box 94249, 1090 GE Amsterdam (Netherlands); Huber, D.; Bedding, T. R. [Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006 (Australia); Karoff, C.; Bruntt, H.; Handberg, R. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Mathur, S.; Metcalfe, T. S. [High Altitude Observatory and Scientific Computing Division, National Center for Atmospheric Research, Boulder, CO 80307 (United States); Mosser, B. [LESIA, CNRS, Universite Pierre et Marie Curie, Universite Denis Diderot, Observatoire de Paris, 92195 Meudon Cedex (France); Quirion, P.-O. [Canadian Space Agency, 6767 Boulevard de l'Aeroport, Saint-Hubert, QC, J3Y 8Y9 (Canada); Appourchaux, T. [Institut d'Astrophysique Spatiale, Universite Paris XI - CNRS (UMR8617), Batiment 121, 91405 Orsay Cedex (France); Campante, T. L. [Centro de Astrofisica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); GarcIa, R. A. [Laboratoire AIM, CEA/DSM, CNRS, Universite Paris Diderot, IRFU/SAp, 91191 Gif-sur-Yvette Cedex (France); Regulo, C. [Departamento de Astrofisica, Universidad de La Laguna, E-38206 La Laguna, Tenerife (Spain); Roxburgh, I. W. [Astronomy Unit, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom)


    We calculate precise stellar radii and surface gravities from the asteroseismic analysis of over 500 solar-type pulsating stars observed by the Kepler space telescope. These physical stellar properties are compared with those given in the Kepler Input Catalog (KIC), determined from ground-based multi-color photometry. For the stars in our sample, we find general agreement but we detect an average overestimation bias of 0.23 dex in the KIC determination of log (g) for stars with log (g){sub KIC} > 4.0 dex, and a resultant underestimation bias of up to 50% in the KIC radii estimates for stars with R{sub KIC} < 2 R{sub sun}. Part of the difference may arise from selection bias in the asteroseismic sample; nevertheless, this result implies there may be fewer stars characterized in the KIC with R {approx} 1 R{sub sun} than is suggested by the physical properties in the KIC. Furthermore, if the radius estimates are taken from the KIC for these affected stars and then used to calculate the size of transiting planets, a similar underestimation bias may be applied to the planetary radii.

  18. Permitted Oxygen Abundances and the Temperature Scale of Metal-Poor Turn-Off Stars

    E-Print Network [OSTI]

    J. Melendez; N. G. Shchukina; I. E. Vasiljeva; I. Ramirez


    We use high quality VLT/UVES published data of the permitted OI triplet and FeII lines to determine oxygen and iron abundances in unevolved (dwarfs, turn-off, subgiants) metal-poor halo stars. The calculations have been performed both in LTE and NLTE, employing effective temperatures obtained with the new infrared flux method (IRFM) temperature scale by Ramirez & Melendez, and surface gravities from Hipparcos parallaxes and theoretical isochrones. A new list of accurate transition probabilities for FeII lines, tied to the absolute scale defined by laboratory measurements, has been used. We find a plateau in the oxygen-to-iron ratio over more than two orders of magnitude in iron abundance (-3.2 < [Fe/H] < -0.7), with a mean [O/Fe] = 0.5 dex (sigma = 0.1 dex), independent of metallicity, temperature and surface gravity. According to the new IRFM Teff scale, the temperatures of turn-off halo stars strongly depend on metallicity, a result that is in excellent qualitative and quantitative agreement with stellar evolution calculations, which predict that the Teff of the turn-off at [Fe/H] = -3 is about 600-700 K higher than that at [Fe/H] = -1.

  19. Group, field and isolated early-type galaxies II. Global trends from nuclear data

    E-Print Network [OSTI]

    Denicolo, G; Terlevich, E; Forbes, D A; Terlevich, A I; Denicolo, Glenda; Terlevich, Roberto; Terlevich, Elena; Forbes, Duncan A.; Terlevich, Alejandro


    We have derived ages, metallicities and enhanced-element ratios [alpha/Fe] for a sample of 83 early-type galaxies essentially in groups, the field or isolated objects. The stellar population properties derived for each galaxy corresponds to the nuclear r_e/8 aperture extraction. The median age found for Es is 5.8 +- 0.6 Gyr and the average metallicity is +0.37 +- 0.03 dex. For S0s, the median age is 3.0 +- 0.6 Gyr and [Z/H] = 0.53 +- 0.04 dex. We compare the distribution of our galaxies in the Hbeta-[MgFe] diagram with Fornax galaxies. Our elliptical galaxies are 3-4 Gyr younger than Es in the Fornax cluster. We find that the galaxies lie in a plane defined by [Z/H] = 0.99 log sigma_0 - 0.46 log Age - 1.60. More massive (larger sigma_0) and older galaxies present, on average, large [alpha/Fe] values, and therefore, must have undergone shorter star-formation timescales. Comparing group against field/isolated galaxies, it is not clear that environment plays an important role in determining their stellar populat...

  20. The SEGUE Stellar Parameter Pipeline. II. Validation with Galactic Globular and Open Clusters

    E-Print Network [OSTI]

    Y. S. Lee; T. C. Beers; T. Sivarani; J. A. Johnson; D. An; R. Wilhelm; C. Allende Prieto; L. Koesterke; P. Re Fiorentin; C. A. L. Bailer-Jones; J. E. Norris; B. Yanny; C. M. Rockosi; H. J. Newberg; K. M. Cudworth; K. Pan


    We validate the performance and accuracy of the current SEGUE (Sloan Extension for Galactic Understanding and Exploration) Stellar Parameter Pipeline (SSPP), which determines stellar atmospheric parameters (effective temperature, surface gravity, and metallicity) by comparing derived overall metallicities and radial velocities from selected likely members of three globular clusters (M 13, M 15, and M 2) and two open clusters (NGC 2420 and M 67) to the literature values. Spectroscopic and photometric data obtained during the course of the original Sloan Digital Sky Survey (SDSS-I) and its first extension (SDSS-II/SEGUE) are used to determine stellar radial velocities and atmospheric parameter estimates for stars in these clusters. Based on the scatter in the metallicities derived for the members of each cluster, we quantify the typical uncertainty of the SSPP values, sigma([Fe/H]) = 0.13 dex for stars in the range of 4500 K < Teff < 7500 K and 2.0 < log g < 5.0, at least over the metallicity interval spanned by the clusters studied (-2.3 < [Fe/H] < 0). The surface gravities and effective temperatures derived by the SSPP are also compared with those estimated from the comparison of the color-magnitude diagrams with stellar evolution models; we find satisfactory agreement. At present, the SSPP underestimates [Fe/H] for near-solar-metallicity stars, represented by members of M 67 in this study, by about 0.3 dex.

  1. The SEGUE Stellar Parameter Pipeline. III. Comparison with High-Resolution Spectroscopy of SDSS/SEGUE Field Stars

    E-Print Network [OSTI]

    C. Allende Prieto; T. Sivarani; T. C. Beers; Y. S. Lee; L. Koesterke; M. Shetrone; C. Sneden; D. L. Lambert; R. Wilhelm; C. M. Rockosi; D. Lai; B. Yanny; I. I. Ivans; J. A. Johnson; W. Aoki; C. A. L. Bailer-Jones; P. Re Fiorentin


    We report high-resolution spectroscopy of 125 field stars previously observed as part of the Sloan Digital Sky Survey and its program for Galactic studies, the Sloan Extension for Galactic Understanding and Exploration (SEGUE). These spectra are used to measure radial velocities and to derive atmospheric parameters, which we compare with those reported by the SEGUE Stellar Parameter Pipeline (SSPP). The SSPP obtains estimates of these quantities based on SDSS ugriz photometry and low-resolution (R = 2000) spectroscopy. For F- and G-type stars observed with high signal-to-noise ratios (S/N), we empirically determine the typical random uncertainties in the radial velocities, effective temperatures, surface gravities, and metallicities delivered by the SSPP to be 2.4 km/s, 130 K (2.2%), 0.21 dex, and 0.11 dex, respectively, with systematic uncertainties of a similar magnitude in the effective temperatures and metallicities. We estimate random errors for lower S/N spectra based on numerical simulations.


    SciTech Connect (OSTI)

    Zahid, H. Jabran; Kewley, Lisa J. [Institute for Astronomy, University of Hawaii at Manoa, 2680 Woodlawn Dr., Honolulu, HI 96822 (United States); Geller, Margaret J.; Hwang, Ho Seong; Fabricant, Daniel G.; Kurtz, Michael J. [Smithsonian Astrophysical Observatory, 60 Garden St., Cambridge, MA 02138 (United States)


    We calculate the stellar mass-metallicity relation at five epochs ranging to z {approx} 2.3. We quantify evolution in the shape of the mass-metallicity relation as a function of redshift; the mass-metallicity relation flattens at late times. There is an empirical upper limit to the gas-phase oxygen abundance in star-forming galaxies that is independent of redshift. From examination of the mass-metallicity relation and its observed scatter, we show that the flattening at late times is a consequence of evolution in the stellar mass where galaxies enrich to this empirical upper metallicity limit; there is also evolution in the fraction of galaxies at a fixed stellar mass that enrich to this limit. The stellar mass where metallicities begin to saturate is {approx}0.7 dex smaller in the local universe than it is at z {approx} 0.8.

  3. What Is The Neon Abundance Of The Sun?

    E-Print Network [OSTI]

    John N. Bahcall; Sarbani Basu; Aldo M. Serenelli


    We have evolved a series of thirteen complete solar models that utilize different assumed heavy element compositions. Models that are based upon the heavy element abundances recently determined by Asplund, Grevesse, and Sauval (2005) are inconsistent with helioseismological measurements. However, models in which the neon abundance is increased by 0.4-0.5 dex to log N(Ne) = 8.29 +- 0.05 (on the scale in which log N(H) = 12) are consistent with the helioseismological measurements even though the other heavy element abundances are in agreement with the determinations of Asplund et al. (2005). These results sharpen and strengthen an earlier study by Antia and Basu (2005). The predicted solar neutrino fluxes are affected by the uncertainties in the composition by less than their 1sigma theoretical uncertainties.


    SciTech Connect (OSTI)

    Hanish, D. J.; Teplitz, H. I.; Capak, P.; Desai, V.; Armus, L.; Brinkworth, C.; Brooke, T.; Colbert, J.; Fadda, D.; Noriega-Crespo, A.; Paladini, R. [Spitzer Science Center, California Institute of Technology, MC 220-6, 1200 E California Blvd., Pasadena, CA 91125 (United States); Frayer, D. [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944 (United States); Huynh, M. [International Centre for Radio Astronomy Research, M468, University of Western Australia, Crawley, WA 6009 (Australia); Lacy, M. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Murphy, E. [The Observatories of the Carnegie Institution for Science, Pasadena, CA 91101 (United States); Scarlata, C. [Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States); Shenoy, S., E-mail: [Space Science Division, NASA Ames Research Center, M/S 245-6, Moffett Field, CA 94035 (United States)


    We use the Spitzer Space Telescope Enhanced Imaging Products and the Spitzer Archival Far-InfraRed Extragalactic Survey to study the spectral energy distributions (SEDs) of spectroscopically confirmed type 1 quasars selected from the Sloan Digital Sky Survey (SDSS). By combining the Spitzer and SDSS data with the Two Micron All Sky Survey, we are able to construct a statistically robust rest-frame 0.1-100 {mu}m type 1 quasar template. We find that the quasar population is well-described by a single power-law SED at wavelengths less than 20 {mu}m, in good agreement with previous work. However, at longer wavelengths, we find a significant excess in infrared luminosity above an extrapolated power-law, along with significant object-to-object dispersion in the SED. The mean excess reaches a maximum of 0.8 dex at rest-frame wavelengths near 100 {mu}m.

  5. Experimental Mg I oscillator strengths and radiative lifetimes for astrophysical applications on metal-poor stars - New data for the Mg I b triplet

    E-Print Network [OSTI]

    M. Aldenius; J. D. Tanner; S. Johansson; H. Lundberg; S. G. Ryan


    The stellar abundance ratio of Mg/Fe is an important tool in diagnostics of galaxy evolution. In order to make reliable measurements of the Mg abundance of stars, it is necessary to have accurate values for the oscillator strength (f-value) of each of the observable transitions. In metal-poor stars the Mg I 3p-4s triplet around 5175 AA (Fraunhofer's so-called b lines) are the most prominent magnesium lines. The lines also appear as strong features in the solar spectrum. We present new and improved experimental oscillator strengths for the optical Mg I 3p-4s triplet, along with experimental radiative lifetimes for six terms in Mg I. With these data we discuss the implications on previous and future abundance analyses of metal-poor stars. The oscillator strengths have been determined by combining radiative lifetimes with branching fractions, where the radiative lifetimes are measured using the laser induced fluorescence technique and the branching fractions are determined using intensity calibrated Fourier Transform (FT) spectra. The FT spectra are also used for determining new accurate laboratory wavelengths for the 3p-4s transitions. The f-values of the Mg I 3p-4s lines have been determined with an absolute uncertainty of 9 %, giving an uncertainty of +-0.04 dex in the log gf values. Compared to values previously used in abundance analyses of metal-poor stars, rescaling to the new values implies an increase of typically 0.04 dex in the magnesium abundance.

  6. Group, field and isolated early-type galaxies II. Global trends from nuclear data

    E-Print Network [OSTI]

    Glenda Denicolo; Roberto Terlevich; Elena Terlevich; Duncan A. Forbes; Alejandro Terlevich


    We have derived ages, metallicities and enhanced-element ratios [alpha/Fe] for a sample of 83 early-type galaxies essentially in groups, the field or isolated objects. The stellar population properties derived for each galaxy corresponds to the nuclear r_e/8 aperture extraction. The median age found for Es is 5.8 +- 0.6 Gyr and the average metallicity is +0.37 +- 0.03 dex. For S0s, the median age is 3.0 +- 0.6 Gyr and [Z/H] = 0.53 +- 0.04 dex. We compare the distribution of our galaxies in the Hbeta-[MgFe] diagram with Fornax galaxies. Our elliptical galaxies are 3-4 Gyr younger than Es in the Fornax cluster. We find that the galaxies lie in a plane defined by [Z/H] = 0.99 log sigma_0 - 0.46 log Age - 1.60. More massive (larger sigma_0) and older galaxies present, on average, large [alpha/Fe] values, and therefore, must have undergone shorter star-formation timescales. Comparing group against field/isolated galaxies, it is not clear that environment plays an important role in determining their stellar population history. In particular, our isolated galaxies show ages differing in more than 8 Gyr. Finally we explore our large spectral coverage to derive log(O/H) metallicity from the N2 indicator and compare it with model-dependent [Z/H]. We find that the O/H abundances are similar for all galaxies, and we can interpret it as if most chemical evolution has already finished in them.


    SciTech Connect (OSTI)

    Madore, Barry F.; Freedman, Wendy L.; Kollmeier, Juna A.; Monson, Andy; Eric Persson, S.; Rich, Jeff A. Jr.; Scowcroft, Victoria; Seibert, Mark [Observatories of the Carnegie Institution of Washington 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Hoffman, Douglas, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail: [Infrared Processing and Analysis Center 770 South Wilson, Pasadena, CA 91125 (United States)


    Using time-resolved, mid-infrared data from the Wide-field Infrared Survey Explorer (WISE) and geometric parallaxes from the Hubble Space Telescope for four Galactic RR Lyrae variables, we derive the following Population II period-luminosity (PL) relations for the WISE [W1], [W2], and [W3] bands at 3.4, 4.6, and 12 ?m, respectively: The slopes and the scatter around the fits are consistent with a smooth extrapolation of those same quantities from previously published K-band observations at 2.2 ?m, where the asymptotic (long-wavelength) behavior is consistent with a period-radius relation with a slope of 0.5. No obvious correlation with metallicity (spanning 0.4 dex in [Fe/H]) is found in the residuals of the four calibrating RR Lyrae stars about the mean PL regression line.

  8. Red Supergiants as Cosmic Abundance Probes: The Sculptor Galaxy NGC 300

    E-Print Network [OSTI]

    Gazak, J Zachary; Evans, Chris; Patrick, Lee; Davies, Ben; Bergemann, Maria; Plez, Bertrand; Bresolin, Fabio; Bender, Ralf; Wegner, Michael; Bonanos, Alceste Z; Williams, Stephen J


    We present a quantitative spectroscopic study of twenty-seven red supergiants in the Sculptor Galaxy NGC 300. J-band spectra were obtained using KMOS on the VLT and studied with state of the art synthetic spectra including NLTE corrections for the strongest diagnostic lines. We report a central metallicity of [Z]= -0.03 +/- 0.05 with a gradient of -0.083 +/- 0.014 [dex/kpc], in agreement with previous studies of blue supergiants and H II-region auroral line measurements. This result marks the first application of the J-band spectroscopic method to a population of individual red supergiant stars beyond the Local Group of galaxies and reveals the great potential of this technique.

  9. Metallicity distribution of bulge planetary nebulae and the [O/Fe] x [Fe/H] relation

    E-Print Network [OSTI]

    W. J. Maciel


    The O/H metallicity distribution of different samples of planetary nebulae in the bulge of the Milky Way and M31 are compared. O/H abundances are converted into [Fe/H] metallicity by the use of theoretical [O/Fe] x [Fe/H] relationships both for the bulge and the solar neighbourhood. It is found that these relationships imply an offset of [Fe/H] abundances by a factor up to 0.5 dex for bulge nebulae. Systematic errors in the O/H abundances as suggested by some recent recombination line work, ON cycling and statistical uncertainties are unable to explain the observed offset, suggesting that the adopted relationship for the bulge probably overestimates the oxygen enhancement relative to iron.


    SciTech Connect (OSTI)

    Majaess, D.; Turner, D. [Department of Astronomy and Physics, Saint Mary's University, Halifax, NS (Canada); Gieren, W., E-mail: [Departamento de Astronomia, Universidad de Concepcion, Concepcion (Chile)


    Evidence is presented which supports findings that the classical Cepheid VI{sub C} period Wesenheit function is relatively insensitive to metallicity. The viability of a recently advocated strong metallicity dependence was evaluated by applying the proposed correction ({gamma} = -0.8 mag dex{sup -1}) to distances established for the Magellanic Clouds via a Galactic VI{sub C} Wesenheit calibration, which is anchored to 10 nearby classical Cepheids with measured Hubble Space Telescope (HST) parallaxes. The resulting {gamma}-corrected distances for the Magellanic Clouds (e.g., Small Magellanic Cloud, {mu}{sub 0,{gamma}} {approx} 18.3) are in significant disagreement with that established from a mean of >300 published estimates (NED-D), and a universal Wesenheit template featuring 11 {delta} Scuti, SX Phe, RR Lyrae, and Type II Cepheid variables with HST/Hipparcos parallaxes. Conversely, adopting a null correction (i.e., {gamma} = 0 mag dex{sup -1}) consolidates the estimates. In tandem with existing evidence, the results imply that variations in chemical composition among Cepheids are a comparatively negligible source of uncertainty for W{sub VIc}-based extragalactic distances and determinations of H{sub 0}. A new approach is described which aims to provide additional Galactic Cepheid calibrators to facilitate subsequent assessments of the VI{sub C} Wesenheit function's relative (in) sensitivity to abundance changes. VVV/UKIDSS/Two Micron All Sky Survey JHK{sub s} photometry for clusters in spiral arms shall be employed to establish a precise galactic longitude-distance relation, which can be applied in certain cases to determine the absolute Wesenheit magnitudes for younger Cepheids.


    SciTech Connect (OSTI)

    Mszros, Sz.; Allende Prieto, C. [Instituto de Astrofsica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain); Holtzman, J. [New Mexico State University, Las Cruces, NM 88003 (United States); Garca Prez, A. E.; Chojnowski, S. D.; Hearty, F. R.; Majewski, S. R. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States); Schiavon, R. P. [Astrophysics Research Institute, Liverpool John Moores University, Egerton Wharf, Birkenhead, Wirral CH41 1LD (United Kingdom); Basu, S. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Bizyaev, D. [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349-0059 (United States); Chaplin, W. J.; Elsworth, Y. [University of Birmingham, School of Physics and Astronomy, Edgbaston, Birmingham B15 2TT (United Kingdom); Cunha, K. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Epstein, C.; Johnson, J. A. [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States); Frinchaboy, P. M. [Texas Christian University, Fort Worth, TX 76129 (United States); Garca, R. A. [Laboratoire AIM, CEA/DSM-CNRS-Universit Paris Diderot, IRFU/SAp, Centre de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Hekker, S. [Astronomical Institute ''Anton Pannekoek'', University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Kallinger, T. [Institute for Astronomy, University of Vienna, Trkenschanzstrasse 17, A-1180 Vienna (Austria); Koesterke, L. [Texas Advanced Computing Center, University of Texas, Austin, TX 78759 (United States); and others


    The Sloan Digital Sky Survey III (SDSS-III) Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a three-year survey that is collecting 10{sup 5} high-resolution spectra in the near-IR across multiple Galactic populations. To derive stellar parameters and chemical compositions from this massive data set, the APOGEE Stellar Parameters and Chemical Abundances Pipeline (ASPCAP) has been developed. Here, we describe empirical calibrations of stellar parameters presented in the first SDSS-III APOGEE data release (DR10). These calibrations were enabled by observations of 559 stars in 20 globular and open clusters. The cluster observations were supplemented by observations of stars in NASA's Kepler field that have well determined surface gravities from asteroseismic analysis. We discuss the accuracy and precision of the derived stellar parameters, considering especially effective temperature, surface gravity, and metallicity; we also briefly discuss the derived results for the abundances of the ?-elements, carbon, and nitrogen. Overall, we find that ASPCAP achieves reasonably accurate results for temperature and metallicity, but suffers from systematic errors in surface gravity. We derive calibration relations that bring the raw ASPCAP results into better agreement with independently determined stellar parameters. The internal scatter of ASPCAP parameters within clusters suggests that metallicities are measured with a precision better than 0.1 dex, effective temperatures better than 150 K, and surface gravities better than 0.2 dex. The understanding provided by the clusters and Kepler giants on the current accuracy and precision will be invaluable for future improvements of the pipeline.

  12. The chemical abundances of the Ap star HD94660

    SciTech Connect (OSTI)

    Giarrusso, M. [Universit di Catania, Dipartimento di Fisica e Astronomia, Sezione Astrofisica, Via S. Sofia 78, 95123 Catania (Italy); INAF - Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania (Italy); INFN - Laboratori Nazionali del Sud (Italy)


    In this work I present the determination of chemical abundances of the Ap star HD94660, a possible rapid oscillating star. As all the magnetic chemically peculiar objects, it presents CNO underabundance and overabundance of iron peak elements of ?100 times and of rare earths up to 4 dex with respect to the Sun. The determination was based on the conversion of the observed equivalent widths into abundances simultaneously to the determination of effective temperature and gravity. Since the Balmer lines of early type stars are very sensitive to the surface gravity while the flux distribution is sensitive to the effective temperature, I have adopted an iterative procedure to match the H{sub ?} line profile and the observed UV-Vis-NIR magnitudes of HD94660 looking for a consistency between the metallicity of the atmosphere model and the derived abundances. From my spectroscopic analysis, this star belongs to the no-rapid oscillating class.

  13. Lithium Depletion of Nearby Young Stellar Associations

    E-Print Network [OSTI]

    Erin Mentuch; Alexis Brandeker; Marten H. van Kerkwijk; Ray Jayawardhana; Peter H. Hauschildt


    We estimate cluster ages from lithium depletion in five pre-main-sequence groups found within 100 pc of the Sun: TW Hydrae Association, Eta Chamaeleontis Cluster, Beta Pictoris Moving Group, Tucanae-Horologium Association and AB Doradus Moving Group. We determine surface gravities, effective temperatures and lithium abundances for over 900 spectra through least squares fitting to model-atmosphere spectra. For each group, we compare the dependence of lithium abundance on temperature with isochrones from pre-main-sequence evolutionary tracks to obtain model dependent ages. We find that the Eta Chamaelontis Cluster and the TW Hydrae Association are the youngest, with ages of 12+/-6 Myr and 12+/-8 Myr, respectively, followed by the Beta Pictoris Moving Group at 21+/-9 Myr, the Tucanae-Horologium Association at 27+/-11 Myr, and the AB Doradus Moving Group at an age of at least 45 Myr (where we can only set a lower limit since the models -- unlike real stars -- do not show much lithium depletion beyond this age). Here, the ordering is robust, but the precise ages depend on our choice of both atmospheric and evolutionary models. As a result, while our ages are consistent with estimates based on Hertzsprung-Russell isochrone fitting and dynamical expansion, they are not yet more precise. Our observations do show that with improved models, much stronger constraints should be feasible: the intrinsic uncertainties, as measured from the scatter between measurements from different spectra of the same star, are very low: around 10 K in effective temperature, 0.05 dex in surface gravity, and 0.03 dex in lithium abundance.


    SciTech Connect (OSTI)

    Du, W.; Luo, A. L.; Zhao, Y. H., E-mail:, E-mail: [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)


    Adopting the SPECTRUM package, which is a stellar spectral synthesis program, we have synthesized a comprehensive set of 2890 near-infrared (NIR) synthetic spectra with a resolution and wavelength sampling similar to the Sloan Digital Sky Survey (SDSS) and the forthcoming Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectra. During the synthesis, we applied the 'New grids of ATLAS9 Model Atmosphere' to develop a grid of local thermodynamic equilibrium model atmospheres for effective temperatures (T{sub eff}) ranging from 3500 to 7500 K, for surface gravities (log g) from 0.5 to 5.0 dex, for metallicities ([Fe/H]) from -4.0 to 0.5 dex, and for solar ([{alpha}/Fe] = 0.0 dex) and non-solar ([{alpha}/Fe] = +0.4 dex) abundances. This synthetic stellar library is composed of 1350 solar scaled abundance (SSA) and 1530 non-solar scaled abundance (NSSA) spectra, grounding on which we have defined a new set of NIR Ca II triplet indices and an index CaT as the sum of the three. These defined indices were automatically measured on every spectrum of the synthetic stellar library and calibrated with the indices computed on the observational spectra from the INDO-U.S. stellar library. In order to check the effect of {alpha}-element enhancement on the so-defined Ca II indices, we compared indices measured on the SSA spectra with those on the NSSA ones at the same trine of stellar parameters (T{sub eff}, log g, [Fe/H]); luckily, little influences of {alpha}-element enhancement were found. Furthermore, comparisons of our synthetic indices with the observational ones from measurements on the INDO-U.S. stellar library, the SDSS-DR7 and SDSS-DR8 spectroscopic survey are presented, respectively, for dwarfs and giants in specific. For dwarfs, our synthetic indices could well reproduce the behaviors of the observational indices versus stellar parameters, which verifies the validity of our index definitions for dwarfs. For giants, the consistency between our synthetic indices and the observational ones does not appear to be as good. However, a new synthetic library of NIR Ca II indices has been founded for deeper studies on the NIR wave band of stellar spectra, and this library is particularly appropriate for the SDSS and the forthcoming LAMOST stellar spectra. We have regressed the strength of the CaT index as a function of stellar parameters for both dwarfs and giants after a series of experimental investigations into relations of the indices with stellar parameters. For dwarfs, log g has little effect on the indices, while [Fe/H] and T{sub eff} play a role together. The leading factor is probably [Fe/H], which changes the strength of the indices by a positive trend. For giants, log g starts to influence the strength of the indices by a negative trend for the metal-poor, and even impact deeply for the metal-rich; besides, [Fe/H] and T{sub eff} still matter. In addition, we briefly discussed the major differences between our Ca II triplet indices and the CaHK doublet indices. Ultimately, a supplemental experiment was carried out to show that spectral noises do have effects on our set of NIR Ca II indices. However, the influence is not weak enough to be ignored if the signal-to-noise ratio falls below 20.

  15. A search for stars of very low metal abundance. VI. Detailed abundances of 313 metal-poor stars

    SciTech Connect (OSTI)

    Roederer, Ian U.; Preston, George W.; Thompson, Ian B.; Shectman, Stephen A.; Burley, Gregory S.; Kelson, Daniel D. [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Sneden, Christopher, E-mail: [Department of Astronomy, University of Texas at Austin, 1 University Station, C1400, Austin, TX 78712 (United States)


    We present radial velocities, equivalent widths, model atmosphere parameters, and abundances or upper limits for 53 species of 48 elements derived from high resolution optical spectroscopy of 313 metal-poor stars. A majority of these stars were selected from the metal-poor candidates of the HK Survey of Beers, Preston, and Shectman. We derive detailed abundances for 61% of these stars for the first time. Spectra were obtained during a 10 yr observing campaign using the Magellan Inamori Kyocera Echelle spectrograph on the Magellan Telescopes at Las Campanas Observatory, the Robert G. Tull Coud Spectrograph on the Harlan J. Smith Telescope at McDonald Observatory, and the High Resolution Spectrograph on the Hobby-Eberly Telescope at McDonald Observatory. We perform a standard LTE abundance analysis using MARCS model atmospheres, and we apply line-by-line statistical corrections to minimize systematic abundance differences arising when different sets of lines are available for analysis. We identify several abundance correlations with effective temperature. A comparison with previous abundance analyses reveals significant differences in stellar parameters, which we investigate in detail. Our metallicities are, on average, lower by ?0.25 dex for red giants and ?0.04 dex for subgiants. Our sample contains 19 stars with [Fe/H] ?3.5, 84 stars with [Fe/H] ?3.0, and 210 stars with [Fe/H] ?2.5. Detailed abundances are presented here or elsewhere for 91% of the 209 stars with [Fe/H] ?2.5 as estimated from medium resolution spectroscopy by Beers, Preston, and Shectman. We will discuss the interpretation of these abundances in subsequent papers.


    SciTech Connect (OSTI)

    Monroe, TalaWanda R.; Melendez, Jorge; Tucci Maia, Marcelo; Freitas, Fabricio C. [Departamento de Astronomia do IAG/USP, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, 05508-900 Sao Paulo, SP (Brazil); Ramirez, Ivan [McDonald Observatory, The University of Texas at Austin, Austin, TX 78712 (United States); Yong, David; Asplund, Martin; Alves-Brito, Alan; Casagrande, Luca [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston, ACT 2611 (Australia); Bergemann, Maria [Max Planck Institute for Astrophysics, Postfach 1317, D-85741 Garching (Germany); Bedell, Megan; Bean, Jacob [Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Ave., Chicago, IL 60637 (United States); Lind, Karin [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Castro, Matthieu; Do Nascimento, Jose-Dias [Departamento de Fisica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Bazot, Michael, E-mail: [Centro de Astrofisica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal)


    We present the first detailed chemical abundance analysis of the old 8.2 Gyr solar twin, HIP 102152. We derive differential abundances of 21 elements relative to the Sun with precisions as high as 0.004 dex ({approx}<1%), using ultra high-resolution (R = 110,000), high S/N UVES spectra obtained on the 8.2 m Very Large Telescope. Our determined metallicity of HIP 102152 is [Fe/H] = -0.013 {+-} 0.004. The atmospheric parameters of the star were determined to be 54 K cooler than the Sun, 0.09 dex lower in surface gravity, and a microturbulence identical to our derived solar value. Elemental abundance ratios examined versus dust condensation temperature reveal a solar abundance pattern for this star, in contrast to most solar twins. The abundance pattern of HIP 102152 appears to be the most similar to solar of any known solar twin. Abundances of the younger, 2.9 Gyr solar twin, 18 Sco, were also determined from UVES spectra to serve as a comparison for HIP 102152. The solar chemical pattern of HIP 102152 makes it a potential candidate to host terrestrial planets, which is reinforced by the lack of giant planets in its terrestrial planet region. The following non-local thermodynamic equilibrium Li abundances were obtained for HIP 102152, 18 Sco, and the Sun: log {epsilon} (Li) = 0.48 {+-} 0.07, 1.62 {+-} 0.02, and 1.07 {+-} 0.02, respectively. The Li abundance of HIP 102152 is the lowest reported to date for a solar twin, and allows us to consider an emerging, tightly constrained Li-age trend for solar twin stars.


    SciTech Connect (OSTI)

    Bentz, Misty C. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Denney, Kelly D.; Vestergaard, Marianne [Dark Cosmology Center, Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Grier, Catherine J.; Peterson, Bradley M.; De Rosa, Gisella; Pogge, Richard W. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Barth, Aaron J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697 (United States); Bennert, Vardha N. [Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 (United States); Canalizo, Gabriela [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Filippenko, Alexei V.; Li Weidong [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Gates, Elinor L. [University of California Observatories/Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Peyton Hall - Ivy Lane, Princeton, NJ 08544 (United States); Malkan, Matthew A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Treu, Tommaso [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Woo, Jong-Hak, E-mail: [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul (Korea, Republic of)


    We present an updated and revised analysis of the relationship between the H{beta} broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create ''AGN-free'' images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the H{beta} time lag, which is assumed to yield the average H{beta} BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R{sub BLR}-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of {alpha}= 0.533{sup +0.035}{sub -0.033}, consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 {+-} 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the R{sub BLR}-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts.


    SciTech Connect (OSTI)

    Shappee, Benjamin J.; Stanek, K. Z., E-mail:, E-mail: [Department of Astronomy, Ohio State University, Columbus, OH 43210 (United States)


    We accurately determine a new Cepheid distance to M101 (NGC 5457) using archival Hubble Space Telescope (HST)/Advanced Camera for Surveys V and I time series photometry of two fields within the galaxy. We make a slight modification to the ISIS image subtraction package to obtain optimal differential light curves from HST data. We discovered 827 Cepheids with periods between 3 and 80 days, the largest extragalactic sample of Cepheids observed with HST by a factor of two. With this large Cepheid sample, we find that the relative distance of M101 from the Large Magellanic Cloud is {Delta}{mu}{sub LMC} = 10.63 {+-} 0.04 (random) {+-} 0.06 (systematic) mag. If we use the geometrically determined maser distance to NGC 4258 as our distance anchor, the distance modulus of M101 is {mu}{sub 0} = 29.04 {+-} 0.05 (random) {+-} 0.18 (systematic) mag or D = 6.4 {+-} 0.2 (random) {+-} 0.5 (systematic) Mpc. The uncertainty is dominated by the maser distance estimate ({+-}0.15 mag), which should improve over the next few years. We determine a steep metallicity dependence, {gamma}, for our Cepheid sample through two methods, yielding {gamma} = -0.80 {+-} 0.21 (random) {+-} 0.06 (systematic) mag dex{sup -1} and {gamma} = -0.72{sup +0.22}{sub -0.25} (random) {+-} 0.06 (systematic) mag dex{sup -1}. We see marginal evidence for variations in the Wesenheit period-luminosity relation slope as a function of deprojected galactocentric radius. We also use the tip of the red giant branch method to independently determine the distance modulus to M101 of {mu}{sub 0} = 29.05 {+-} 0.06 (random) {+-} 0.12 (systematic) mag.

  19. Inhibition of extracellular protease secretion by Aspergillus niger using cell

    E-Print Network [OSTI]

    Gu, Tingyue

    , Forma Scientific Inc.) The spores were harvested by adding 20 mL of sterilized distilled water composition (g/L): 3 yeast extract, 3 malt extract, 5 peptone, and 10 dex- trose. Culture conditions Shake

  20. ComPAS'2013 : RenPar'21 / SympA'15/ CFSE'9 Grenoble, France, du 16 au 18 janvier 2013

    E-Print Network [OSTI]

    Boyer, Edmond

    MV, CSR 1. Introduction La simulation de rservoir (rserve naturelle d'hydrocarbures) est l d'ex- traction, de calculer le rendement en hydrocarbures et aussi d'exprimenter de nouvelles mth

  1. Descriptive logs, skeletonized samples, and photographs of core...

    Open Energy Info (EERE)


  2. Type-Ia Supernova Remnant Shell At $Z=3.5$ Seen In The Three Sightlines Toward The Gravitationally Lensed Qso B1422+231

    E-Print Network [OSTI]

    Hamano, Satoshi; Kondo, Sohei; Tsujimoto, Takuji; Okoshi, Katsuya; Shigeyama, Toshikazu


    Using the Subaru 8.2m Telescope with an IRCS Echelle spectrograph, we obtained high-resolution (R=10,000) near-infrared (1.01-1.38 \\mu m) spectra of images A and B of the gravitationally lensed QSO B1422+231 (z=3.628) consisting of four known lensed images. We detected MgII absorption lines at z=3.54, which show a large variance of column densities (~ 0.3 dex) and velocities (~ 10 km/s) between the sightlines A and B with a projected separation of only 8.4h_{70}^{-1} pc at the redshift. This is the smallest spatial structure of the high-z gas clouds ever detected after Rauch et al. found a 20-pc scale structure for the same z=3.54 absorption system using optical spectra of images A and C. The observed systematic variances imply that the system is an expanding shell as originally suggested by Rauch et al. By combining the data for three sightlines, we managed to constrain the radius and expansion velocity of the shell (~ 50-100 pc, 130 km/s), concluding that the shell is truly a supernova remnant (SNR) rather ...


    SciTech Connect (OSTI)

    Bennert, Vardha Nicola; Treu, Tommaso; Le Bris, Alexandre; Auger, Matthew W. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Woo, Jong-Hak; Malkan, Matthew A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Gallagher, Sarah [Department of Physics and Astronomy, University of Western Ontario, 1151 Richmond Street, London, ON N6A 3K7 (Canada); Blandford, Roger D., E-mail: bennert@physics.ucsb.ed, E-mail: tt@physics.ucsb.ed, E-mail: mauger@physics.ucsb.ed, E-mail: woo@astro.ucla.ed, E-mail: malkan@astro.ucla.ed, E-mail:, E-mail: sgalla4@uwo.c, E-mail: rdb@slac.stanford.ed [Kavli Institute for Particle Astrophysics and Cosmology, Stanford, CA 94305 (United States)


    From high-resolution images of 23 Seyfert-1 galaxies at z = 0.36 and z = 0.57 obtained with the Near-Infrared Camera and Multi-Object Spectrometer on board the Hubble Space Telescope (HST), we determine host-galaxy morphology, nuclear luminosity, total host-galaxy luminosity, and spheroid luminosity. Keck spectroscopy is used to estimate black hole mass (M{sub BH}). We study the cosmic evolution of the M{sub BH}-spheroid luminosity (L{sub sph}) relation. In combination with our previous work, totaling 40 Seyfert-1 galaxies, the covered range in BH mass is substantially increased, allowing us to determine for the first time intrinsic scatter and correct evolutionary trends for selection effects. We re-analyze archival HST images of 19 local reverberation-mapped active galaxies to match the procedure adopted at intermediate redshift. Correcting spheroid luminosity for passive luminosity evolution and taking into account selection effects, we determine that at fixed present-day V-band spheroid luminosity, M{sub BH}/L{sub sph} propor to(1 + z){sup 2.8+}-{sup 1.2}. When including a sample of 44 quasars out to z = 4.5 taken from the literature, with luminosity and BH mass corrected to a self-consistent calibration, we extend the BH mass range to over 2 orders of magnitude, resulting in M{sub BH}/L{sub sph} propor to(1 + z){sup 1.4+}-{sup 0.2}. The intrinsic scatter of the relation, assumed constant with redshift, is 0.3 +- 0.1 dex (<0.6 dex at 95% CL). The evolutionary trend suggests that BH growth precedes spheroid assembly. Interestingly, the M{sub BH}-total-host-galaxy-luminosity relation is apparently non-evolving. It hints at either a more fundamental relation or that the spheroid grows by a redistribution of stars. However, the high-z sample does not follow this relation, indicating that major mergers may play the dominant role in growing spheroids above z approx = 1.


    SciTech Connect (OSTI)

    Sanchez Almeida, J.; Allende Prieto, C., E-mail:, E-mail: [Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain)


    Large spectroscopic surveys require automated methods of analysis. This paper explores the use of k-means clustering as a tool for automated unsupervised classification of massive stellar spectral catalogs. The classification criteria are defined by the data and the algorithm, with no prior physical framework. We work with a representative set of stellar spectra associated with the Sloan Digital Sky Survey (SDSS) SEGUE and SEGUE-2 programs, which consists of 173,390 spectra from 3800 to 9200 A sampled on 3849 wavelengths. We classify the original spectra as well as the spectra with the continuum removed. The second set only contains spectral lines, and it is less dependent on uncertainties of the flux calibration. The classification of the spectra with continuum renders 16 major classes. Roughly speaking, stars are split according to their colors, with enough finesse to distinguish dwarfs from giants of the same effective temperature, but with difficulties to separate stars with different metallicities. There are classes corresponding to particular MK types, intrinsically blue stars, dust-reddened, stellar systems, and also classes collecting faulty spectra. Overall, there is no one-to-one correspondence between the classes we derive and the MK types. The classification of spectra without continuum renders 13 classes, the color separation is not so sharp, but it distinguishes stars of the same effective temperature and different metallicities. Some classes thus obtained present a fairly small range of physical parameters (200 K in effective temperature, 0.25 dex in surface gravity, and 0.35 dex in metallicity), so that the classification can be used to estimate the main physical parameters of some stars at a minimum computational cost. We also analyze the outliers of the classification. Most of them turn out to be failures of the reduction pipeline, but there are also high redshift QSOs, multiple stellar systems, dust-reddened stars, galaxies, and, finally, odd spectra whose nature we have not deciphered. The template spectra representative of the classes are publicly available in the online journal.

  5. Multicolor Surface Photometry of Lenticulars I. The Data

    E-Print Network [OSTI]

    Barway, S; Kembhavi, A K; Pandey, S K; Barway, Sudhanshu; Kembhavi, Ajit K.


    We present in this paper multicolor surface and aperture photometry in the B, V, R and K' bands for a sample of 34 lenticular galaxies from the UGC catalogue. From surface photometric analysis, we obtain radial profiles of surface brightness, colors, ellipticity, position angle and the Fourier coefficients which describe the departure of isophotal shapes from purely elliptical form and find the presence of dust lanes, patches and ring like structure in several galaxies in the sample. We obtain total integrated magnitudes and colors and find that these are in good agreement with the values from the RC3 catalogue. Isophotal colors are correlated with each other, following the sequence expected for early-type galaxies. The color gradients in lenticulars are more negative than the corresponding gradients in ellipticals. There is a good correlation between B-V and B-R color gradients, and the mean gradient in the B-V, B-R and V-K' colors are -0.13+/-0.06, -0.18+/-0.06, -0.25+/-0.11 magnitude per dex in radius resp...

  6. Multicolor Surface Photometry of Lenticulars I. The Data

    E-Print Network [OSTI]

    Sudhanshu Barway; Y. D. Mayya; Ajit K. Kembhavi; S. K. Pandey


    We present in this paper multicolor surface and aperture photometry in the B, V, R and K' bands for a sample of 34 lenticular galaxies from the UGC catalogue. From surface photometric analysis, we obtain radial profiles of surface brightness, colors, ellipticity, position angle and the Fourier coefficients which describe the departure of isophotal shapes from purely elliptical form and find the presence of dust lanes, patches and ring like structure in several galaxies in the sample. We obtain total integrated magnitudes and colors and find that these are in good agreement with the values from the RC3 catalogue. Isophotal colors are correlated with each other, following the sequence expected for early-type galaxies. The color gradients in lenticulars are more negative than the corresponding gradients in ellipticals. There is a good correlation between B-V and B-R color gradients, and the mean gradient in the B-V, B-R and V-K' colors are -0.13+/-0.06, -0.18+/-0.06, -0.25+/-0.11 magnitude per dex in radius respectively.

  7. The COS/UVES Absorption Survey of the Magellanic Stream: II. Evidence for a complex enrichment history of the Stream from the Fairall 9 sightline

    E-Print Network [OSTI]

    Richter, Philipp; Wakker, Bart P; Lehner, Nicolas; Howk, J Christopher; Bland-Hawthorn, Joss; Bekhti, Nadya Ben; Fechner, Cora


    We present a multi-wavelength study of the Magellanic Stream (MS), a massive gaseous structure in the Local Group that is believed to represent material stripped from the Magellanic Clouds. We use ultraviolet, optical and radio data obtained with HST/COS, VLT/UVES, FUSE and GASS to study metal abundances and physical conditions in the Stream toward the quasar Fairall 9. Line absorption in the MS is detected from a large number of metal ions and from molecular hydrogen. From the analysis of unsaturated SII absorption, in combination with a detailed photoionization model, we obtain a surprisingly high alpha abundance in the Stream toward Fairall 9 of [S/H]=-0.30pm0.04 (0.5 solar). This value is 5 times higher than what is found along other MS sightlines based on similar COS/UVES data sets. In contrast, the measured nitrogen abundance is found to be substantially lower ([N/H]=-1.15pm0.06), implying a very low [alpha/N] ratio of -0.85 dex. The substantial differences in the chemical composition of the Magellanic ...

  8. Weighing Galaxy Disks with the Baryonic Tully-Fisher Relation

    E-Print Network [OSTI]

    McGaugh, Stacy


    We estimate the stellar masses of disk galaxies with two independent methods: a photometrically self-consistent color$-$mass-to-light ratio relation (CMLR) from population synthesis models, and the Baryonic Tully-Fisher relation (BTFR) calibrated by gas rich galaxies. These two methods give consistent results. The CMLR correctly converts distinct Tully-Fisher relations in different bands into the same BTFR. The BTFR is consistent with $M_b \\propto V_f^4$ over nearly six decades in mass, with no hint of a change in slope over that range. The intrinsic scatter in the BTFR is negligible, implying that the IMF of disk galaxies is effectively universal. The gas rich BTFR suggests an absolute calibration of the stellar mass scale that yields nearly constant mass-to-light ratios in the near-infrared (NIR): $0.57\\;M_{\\odot}/L_{\\odot}$ in $K_s$ and $0.45\\;M_{\\odot}/L_{\\odot}$ at $3.6\\mu$. There is only modest intrinsic scatter ($\\sim 0.12$ dex) about these typical values. There is no discernible variation with color o...

  9. On the maximum value of the cosmic abundance of oxygen and the oxygen yield

    E-Print Network [OSTI]

    L. S. Pilyugin; T. X. Thuan; J. M. Vilchez


    We search for the maximum oxygen abundance in spiral galaxies. Because this maximum value is expected to occur in the centers of the most luminous galaxies, we have constructed the luminosity - central metallicity diagram for spiral galaxies, based on a large compilation of existing data on oxygen abundances of HII regions in spiral galaxies. We found that this diagram shows a plateau at high luminosities (-22.3 oxygen abundance 12+log(O/H) ~ 8.87. This provides strong evidence that the oxygen abundance in the centers of the most luminous metal-rich galaxies reaches the maximum attainable value of oxygen abundance. Since some fraction of the oxygen (about 0.08 dex) is expected to be locked into dust grains, the maximum value of the true gas+dust oxygen abundance in spiral galaxies is 12+log(O/H) ~ 8.95. This value is a factor of ~ 2 higher than the recently estimated solar value. Based on the derived maximum oxygen abundance in galaxies, we found the oxygen yield to be about 0.0035, depending on the fraction of oxygen incorporated into dust grains.

  10. On the deduction of galaxy abundances with evolutionary neural networks

    E-Print Network [OSTI]

    Michael Taylor; Angeles I. Diaz


    A growing number of indicators are now being used with some confidence to measure the metallicity(Z) of photoionisation regions in planetary nebulae, galactic HII regions(GHIIRs), extra-galactic HII regions(EGHIIRs) and HII galaxies(HIIGs). However, a universal indicator valid also at high metallicities has yet to be found. Here, we report on a new artificial intelligence-based approach to determine metallicity indicators that shows promise for the provision of improved empirical fits. The method hinges on the application of an evolutionary neural network to observational emission line data. The network's DNA, encoded in its architecture, weights and neuron transfer functions, is evolved using a genetic algorithm. Furthermore, selection, operating on a set of 10 distinct neuron transfer functions, means that the empirical relation encoded in the network solution architecture is in functional rather than numerical form. Thus the network solutions provide an equation for the metallicity in terms of line ratios without a priori assumptions. Tapping into the mathematical power offered by this approach, we applied the network to detailed observations of both nebula and auroral emission lines in the optical for a sample of 96 HII-type regions and we were able to obtain an empirical relation between Z and S23 with a dispersion of only 0.16 dex. We show how the method can be used to identify new diagnostics as well as the nonlinear relationship supposed to exist between the metallicity Z, ionisation parameter U and effective (or equivalent) temperature T*.

  11. The Hubble Space Telescope UV Legacy Survey of Galactic Globular Clusters. IV. Helium content and relative age of multiple stellar populations within NGC 6352

    E-Print Network [OSTI]

    Nardiello, D; Milone, A P; Marino, A F; Bedin, L R; Anderson, J; Aparicio, A; Bellini, A; Cassisi, S; D'Antona, F; Hidalgo, S; Ortolani, S; Pietrinferni, A; Renzini, A; Salaris, M; van der Marel, R P; Vesperini, E


    In this paper we combine WFC3/UVIS F275W, F336W, and F438W data from the "UV Legacy Survey of Galactic Globular Clusters: Shedding Light on Their Populations and Formation" (GO-13297) HST Treasury program with F606W, F625W, F658N, and F814W ACS archive data for a multi-wavelength study of the globular cluster NGC 6352. In the color-magnitude and two-color diagrams obtained with appropriate combination of the photometry in the different bands we separate two distinct stellar populations and trace them from the main sequence to the subgiant, red giant, horizontal and asymptotic giant branches. We infer that the two populations differ in He by Delta Y=0.029+/-0.006. With a new method, we also estimate the age difference between the two sequences. Assuming no difference in [Fe/H] and [alpha/Fe], and the uncertainties on Delta Y, we found a difference in age between the two populations of 10+/-120 Myr. If we assume [Fe/H] and [alpha/Fe] differences of 0.02 dex (well within the uncertainties of spectroscopic measur...

  12. On the age of Galactic bulge microlensed dwarf and subgiant stars

    E-Print Network [OSTI]

    Valle, G; Moroni, P G Prada; Degl'Innocenti, S


    Recent results by Bensby and collaborators on the ages of microlensed stars in the Galactic bulge have challenged the picture of an exclusively old stellar population. However, these age estimates have not been independently confirmed. In this paper we verify these results by means of a grid-based method and quantify the systematic biases that might be induced by some assumptions adopted to compute stellar models. We explore the impact of increasing the initial helium abundance, neglecting the element microscopic diffusion, and changing the mixing-length calibration in theoretical stellar track computations. We adopt the SCEPtER pipeline with a novel stellar model grid for metallicities [Fe/H] from -2.00 to 0.55 dex, and masses in the range [0.60; 1.60] Msun from the ZAMS to the helium flash at the red giant branch tip. We show for the considered evolutionary phases that our technique provides unbiased age estimates. Our age results are in good agreement with Bensby and collaborators findings and show 16 star...

  13. Extending Virial Black Hole Mass Estimates to Low-Luminosity or Obscured AGN: the cases of NGC 4395 and MCG -01-24-012

    E-Print Network [OSTI]

    La Franca, F; Ricci, F; Sani, E; Brusa, M; Maiolino, R; Fiore, F; Marconi, A; Vignali, C


    In the last decade, using single epoch (SE) virial based spectroscopic optical observations, it has been possible to measure the black hole (BH) mass on large type 1 Active Galactic Nuclei (AGN) samples. However this kind of measurements can not be applied on those obscured type 2 and/or low luminosity AGN where the nuclear component does not dominate in the optical. We have derived new SE relationships, based on the FWHM and luminosity of the broad line region component of the Pabeta emission line and/or the hard X-ray luminosity in the 14-195 keV band, which have the prospect of better working with low luminosity or obscured AGN. The SE relationships have been calibrated in the 10^5-10^9 M_sol mass range, using a sample of AGN whose BH masses have been previously measured using reverberation mapping techniques. Our tightest relationship between the reverberation-based BH mass and the SE virial product has an intrinsic spread of 0.20 dex. Thanks to these SE relations, in agreement with previous estimates, we...

  14. Clues on the evolution of abundance gradients and on AGB nucleosynthesis

    E-Print Network [OSTI]

    Stasinska, G; Bresolin, F; Tsamis, Yi


    We have obtained deep spectra of 26 planetary nebulae (PNe) and 9 compact HII regions in the nearby spiral galaxy NGC 300, and analyzed them together with those of the giant HII regions previously observed. We have determined the physical properties of all these objects and their He, N, O, Ne, S and Ar abundances in a consistent way. We find that, globally, compact HII regions have abundance ratios similar to those of giant HII regions, while PNe have systematically larger N/O ratios and similar Ne/O and Ar/O ratios. We demonstrate that the nitrogen enhancement in PNe cannot be only due to second dredge-up in the progenitor stars, since their initial masses are around 2--2.5\\,\\msun. An extra mixing process is required, perhaps driven by stellar rotation. Concerning the radial abundance distribution, PNe behave differently from HII regions: in the central part of the galaxy their average O/H abundance ratio is 0.15 dex smaller. Their abundance dispersion at any galactocentric radius is significantly larger tha...


    SciTech Connect (OSTI)

    Razoumov, Alexei O. [Institute for Computational Astrophysics, Department of Astronomy and Physics, Saint Mary's University, Halifax, NS, B3H 3C3 (Canada); Sommer-Larsen, Jesper, E-mail: razoumov@ap.smu.c, E-mail: jslarsen@astro.ku.d [Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstrasse 2, D-85748 Garching (Germany)


    We compute the escape of ionizing radiation from galaxies in the redshift interval z = 4-10, i.e., during and after the epoch of reionization, using a high-resolution set of galaxies, formed in fully cosmological simulations. The simulations invoke early, energetic feedback, and the galaxies evolve into a realistic population at z = 0. Our galaxies cover nearly four orders of magnitude in masses (10{sup 7.8}-10{sup 11.5} M{sub sun}) and more than five orders in star formation rates (10{sup -3.5}-10{sup 1.7} M{sub sun} yr{sup -1}), and we include an approximate treatment of dust absorption. We show that the source-averaged Lyman limit escape fraction at z = 10.4 is close to 80% declining monotonically with time as more massive objects build up at lower redshifts. Although the amount of dust absorption is uncertain to 1-1.5 dex, it is tightly correlated with metallicity; we find that dust is unlikely to significantly impact the observed UV output. These results support reionization by stellar radiation from low-luminosity dwarf galaxies and are also compatible with Lyman continuum observations and theoretical predictions at z {approx} 3-4.

  16. Artificial neural network based calibrations for the prediction of galactic [NII] $\\lambda$ 6584 and H$\\alpha$ line luminosities

    E-Print Network [OSTI]

    Teimoorinia, Hossein


    The artificial neural network (ANN) is a well-established mathematical technique for data prediction, based on the identification of correlations and pattern recognition in input training sets. We present the application of ANNs to predict the emission line luminosities of H$\\alpha$ and [NII] $\\lambda$6584 in galaxies. These important spectral diagnostics are used for metallicities, active galactic nuclei (AGN) classification and star formation rates, yet are shifted into the infra-red for galaxies above $z \\sim 0.5$, or may not be covered in spectra with limited wavelength coverage. The ANN is trained with a large sample of emission line galaxies selected from the Sloan Digital Sky Survey using various combinations of emission lines and stellar mass. The ANN is tested for galaxies dominated by both star formation and AGN; in both cases the H$\\alpha$ and [NII] $\\lambda$6584 line luminosities can be predicted with a scatter $\\sigma <$ 0.1 dex. We also show that the performance of the ANN does not depend sig...

  17. Improved Laboratory Transition Probabilities for Ce II, Application to the Cerium Abundances of the Sun and Five r-process Rich, Metal-Poor Stars, and Rare Earth Lab Data

    E-Print Network [OSTI]

    Lawler, J E; Cowan, J J; Ivans, I I; Hartog, E A Den


    Recent radiative lifetime measurements accurate to +/- 5% using laser-induced fluorescence (LIF) on 43 even-parity and 15 odd-parity levels of Ce II have been combined with new branching fractions measured using a Fourier transform spectrometer (FTS) to determine transition probabilities for 921 lines of Ce II. This improved laboratory data set has been used to determine a new solar photospheric Ce abundance, log epsilon = 1.61 +/- 0.01 (sigma = 0.06 from 45 lines), a value in excellent agreement with the recommended meteoritic abundance, log epsilon = 1.61 +/- 0.02. Revised Ce abundances have also been derived for the r-process-rich metal-poor giant stars BD+17 3248, CS 22892-052, CS 31082-001, HD 115444 and HD 221170. Between 26 and 40 lines were used for determining the Ce abundance in these five stars, yielding a small statistical uncertainty of 0.01 dex similar to the Solar result. The relative abundances in the metal-poor stars of Ce and Eu, a nearly pure r-process element in the Sun, matches r-process ...

  18. Carbon and Strontium Abundances of Metal-Poor Stars

    E-Print Network [OSTI]

    David K. Lai; Jennifer A. Johnson; Michael Bolte; Sara Lucatello


    We present carbon and strontium abundances for 100 metal-poor stars measured from R$\\sim $7000 spectra obtained with the Echellette Spectrograph and Imager at the Keck Observatory. Using spectral synthesis of the G-band region, we have derived carbon abundances for stars ranging from [Fe/H]$=-1.3$ to [Fe/H]$=-3.8$. The formal errors are $\\sim 0.2$ dex in [C/Fe]. The strontium abundance in these stars was measured using spectral synthesis of the resonance line at 4215 {\\AA}. Using these two abundance measurments along with the barium abundances from our previous study of these stars, we show it is possible to identify neutron-capture-rich stars with our spectra. We find, as in other studies, a large scatter in [C/Fe] below [Fe/H]$ = -2$. Of the stars with [Fe/H]$carbon-rich metal-poor stars. The Sr and Ba abundances show that three of the carbon-rich stars are neutron-capture-rich, while two have normal Ba and Sr. This fraction of carbon enhanced stars is consistent with other studies that include this metallicity range.

  19. The Baltimore and Utrecht models for cluster dissolution

    E-Print Network [OSTI]

    Henny J. G. L. M. Lamers


    The analysis of the age distributions of star cluster samples of different galaxies has resulted in two very different empirical models for the dissolution of star clusters: the Baltimore model and the Utrecht model. I describe these two models and their differences. The Baltimore model implies that the dissolution of star clusters is mass independent and that about 90% of the clusters are destroyed each age dex, up to an age of about a Gyr, after which point mass-dependent dissolution from two-body relaxation becomes the dominant mechanism. In the Utrecht model, cluster dissolution occurs in three stages: (i) mass-independent infant mortality due to the expulsion of gas up to about 10 Myr; (ii) a phase of slow dynamical evolution with strong evolutionary fading of the clusters lasting up to about a Gyr; and (iii) a phase dominated by mass dependent-dissolution, as predicted by dynamical models. I describe the cluster age distributions for mass-limited and magnitude-limited cluster samples for both models. I refrain from judging the correctness of these models.


    SciTech Connect (OSTI)

    Boeche, C.; Williams, M.; De Jong, R. S.; Steinmetz, M. [Leibniz-Institut fuer Astrophysik Potsdam (AIP), D-14482 Potsdam (Germany); Siebert, A.; Bienayme, O. [Observatoire Astronomique de Strasbourg, Universite de Strasbourg, CNRS, UMR 7550, F-67000 Strasbourg (France); Fulbright, J. P.; Ruchti, G. R. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Bland-Hawthorn, J. [Sydney Institute for Astronomy, School of Physics A28, University of Sydney, NSW 2006 (Australia); Campbell, R. [Department of Physics and Astronomy, Western Kentucky University, Bowling Green, KY (United States); Freeman, K. C. [Research School of Astronomy and Astrophysics, Australia National University, Weston Creek, Canberra ACT 2611 (Australia); Gibson, B. K. [Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE (United Kingdom); Gilmore, G. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Grebel, E. K. [Astronomisches Rechen-Institut, Zentrum fuer Astronomie der Universitaet Heidelberg, D-69120 Heidelberg (Germany); Helmi, A. [Kapteyn Astronomical Institute, University of Groningen, 9700 AV Groningen (Netherlands); Munari, U. [INAF Osservatorio Astronomico di Padova, Asiago I-36012 (Italy); Navarro, J. F. [Department of Physics and Astronomy, University of Victoria, Victoria BC V8W 3P6 (Canada); Parker, Q. A.; Reid, W. [Department of Physics and Astronomy, Faculty of Sciences, Macquarie University, Sydney, NSW 2109 (Australia); Seabroke, G. M. [Mullard Space Science Laboratory, University College London, Holmbury, St. Mary RH5 6NT (United Kingdom); and others


    We present chemical elemental abundances for 36,561 stars observed by the RAdial Velocity Experiment (RAVE), an ambitious spectroscopic survey of our Galaxy at Galactic latitudes |b| > 25 Degree-Sign and with magnitudes in the range 9 dex, as judged from accuracy tests performed on synthetic and real spectra. Abundances are estimated through a dedicated processing pipeline in which the curve of growth of individual lines is obtained from a library of absorption line equivalent widths to construct a model spectrum that is then matched to the observed spectrum via a {chi}{sup 2} minimization technique. We plan to extend this pipeline to include estimates for other elements, such as oxygen and sulfur, in future data releases.

  1. Spectroscopic Study on the Beryllium Abundances of Red Giant Stars

    E-Print Network [OSTI]

    Takeda, Yoichi


    An extensive spectroscopic study was carried out for the beryllium abundances of 200 red giants (mostly of late G and early K type), which were determined from the near-UV Be II 3131.066 line based on high-dispersion spectra obtained by Subaru/HDS, with an aim of investigating the nature of surface Be contents in these evolved giants; e.g., dependence upon stellar parameters, degree of peculiarity along with its origin and build-up timing. We found that Be is considerably deficient (to widely different degree from star to star) in the photosphere of these evolved giants by ~1-3 dex (or more) compared to the initial abundance. While the resulting Be abundances (A(Be)) appear to weakly depend upon T_eff, log g, [Fe/H], M, age, and v_sin i, this may be attributed to the metallicity dependence of A(Be) coupled with the mutual correlation between these stellar parameters, since such tendencies almost disappear in the metallicity-scaled Be abundance ([Be/Fe]). By comparing the Be abundances (as well as their correl...

  2. Discovery of a peculiar Cepheid-like star towards the northern edge of the Small Magellanic Cloud

    E-Print Network [OSTI]

    Marquette, J B; Franois, P; Beaulieu, J P; Doublier, V; Lesquoy, E; Milsztajn, A; Pritchard, J; Schwarzenberg-Czerny, A; Afonso, C; Albert, J N; Andersen, J; Ansari, R; Aubourg, E; Bareyre, P; Charlot, X; Coutures, C; Ferlet, R; Fouqu, P; Glicenstein, J F; Goldman, B; Gould, A; Graff, D; Gros, M; Hassinski, J; Hamadache, C; De Kat, J; Guillou, L Le; Loup, C; Magneville, C; Maurice, E; Maury, A; Moniez, M; Palanque-Delabrouille, Nathalie; Perdereau, O; Rahal, Y R; Rich, J; Spiro, M; Vidal-Madjar, A; Zylberajch, S


    For seven years, the EROS-2 project obtained a mass of photometric data on variable stars. We present a peculiar Cepheid-like star, in the direction of the Small Magellanic Cloud, which demonstrates unusual photometric behaviour over a short time interval. We to report on data of the photometriy acquired by the MARLY telescope and spectroscopy from the EFOSC instrument for this star, called EROS2 J005135-714459(sm0060n13842), which resembles the unusual Cepheid HR 7308. The light curve of our target is analysed using the Analysis of Variance method to determine a pulsational period of 5.5675 days. A fit of time-dependent Fourier coefficients is performed and a search for proper motion is conducted. The light curve exhibits a previously unobserved and spectacular change in both mean magnitude and amplitude, which has no clear theoretical explanation. Our analysis of the spectrum implies a radial velocity of 104 km s$^{-1}$ and a metallicity of -0.4$\\pm$0.2 dex. In the direction of right ascension, we measure a...

  3. A very reduced upper limit on the interstellar abundance of beryllium

    E-Print Network [OSTI]

    Guillaume Hbrard; Martin Lemoine; Roger Ferlet; Alfred Vidal-Madjar


    We present the results of observations of the $\\lambda 3130.4$ \\AA interstellar absorption line of Be II in the direction of zeta Per. The data were obtained at the Canada-France-Hawaii 3.6m Telescope using the Coud\\'e f/4 Gecko spectrograph at a resolving power $\\simeq 1.1 \\times 10^5$, and a signal-to-noise ratio S/N $\\simeq$ 2000. The Be II line is not detected, and we obtain an upper limit on the equivalent width $W_{3130.4}\\leq30$ $\\mu$\\AA. This upper limit is 7 times below the lowest upper limit ever reported hitherto. The derived interstellar abundance is ($^9$Be/H) $\\leq 7 \\times 10^{-13}$, not corrected for the depletion of Be onto interstellar grains; it corresponds to an upper limit $\\delta_{Be} \\leq -1.5$ dex on the depletion factor of Be. As such, it argues in favour of models of formation of dust grains in stellar atmospheres.

  4. Population Effects on the Metallicity Distribution Function Derived From the Red Giant Branch

    E-Print Network [OSTI]

    Ordoez, Antonio J


    We have tested the reliability of the red giant branch (RGB) as a metallicity indicator accounting for observational errors as well as the complexity of star formation histories (SFHs) and chemical evolution histories observed in various stellar systems. We generate model color-magnitude diagrams (CMDs) produced with a variety of evolutionary histories and compare the resultant metallicity estimates from the colors and magnitudes of RGB stars to the true input metallicities. We include realistic models for photometric errors and completeness in our synthetic CMDs. As expected, for simple simple stellar populations dominated by old stars, the RGB provides a very accurate estimate of the modular metallicity value for a population. An error in the age of a system targeted for this type of study may produce metallicity errors of a few tenths of a dex. The size of this metallicity error depends linearly on the age error, and we find this dependence to be stronger with more precise photometry. If the population has...

  5. Observational constraints on the progenitors of core-collapse supernovae : the case for missing high mass stars

    E-Print Network [OSTI]

    Smartt, S J


    Over the last 15 years, the supernova community has endeavoured to identify progenitor stars of core-collapse supernovae in high resolution archival images of their galaxies.This review compiles results (from 1999 - 2013) in a distance limited sample and discusses the implications. The vast majority of the detections of progenitor stars are of type II-P, II-L or IIb with one type Ib progenitor system detected and many more upper limits for progenitors of Ibc supernovae (14). The data for these 45 supernovae progenitors illustrate a remarkable deficit of high luminosity stars above an apparent limit of Log L ~= 5.1 dex. For a typical Salpeter IMF, one would expect to have found 13 high luminosity and high mass progenitors. There is, possibly, only one object in this time and volume limited sample that is unambiguously high mass (the progenitor of SN2009ip). The possible biases due to the influence of circumstellar dust and sample selection methods are reviewed. It does not appear likely that these can explain ...


    SciTech Connect (OSTI)

    Childress, M.; Aldering, G.; Aragon, C.; Bailey, S.; Fakhouri, H. K.; Hsiao, E. Y.; Kim, A. G.; Loken, S. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, 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 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.; Kerschhaggl, M.; Kowalski, M. [Physikalisches Institut, Universitaet Bonn, Nussallee 12, D-53115 Bonn (Germany); Chotard, N.; Copin, Y.; Gangler, E. [Universite de Lyon, F-69622, Lyon (France); Universite de Lyon 1, Villeurbanne (France); CNRS/IN2P3, Institut de Physique Nucleaire de Lyon (France); and others


    We examine the relationship between Type Ia supernova (SN Ia) Hubble residuals and the properties of their host galaxies using a sample of 115 SNe Ia from the Nearby Supernova Factory. We use host galaxy stellar masses and specific star formation rates fitted from photometry for all hosts, as well as gas-phase metallicities for a subset of 69 star-forming (non-active galactic nucleus) hosts, to show that the SN Ia Hubble residuals correlate with each of these host properties. With these data we find new evidence for a correlation between SN Ia intrinsic color and host metallicity. When we combine our data with those of other published SN Ia surveys, we find the difference between mean SN Ia brightnesses in low- and high-mass hosts is 0.077 {+-} 0.014 mag. When viewed in narrow (0.2 dex) bins of host stellar mass, the data reveal apparent plateaus of Hubble residuals at high and low host masses with a rapid transition over a short mass range (9.8 {<=} log (M{sub *}/M{sub Sun }) {<=} 10.4). Although metallicity has been a favored interpretation for the origin of the Hubble residual trend with host mass, we illustrate how dust in star-forming galaxies and mean SN Ia progenitor age both evolve along the galaxy mass sequence, thereby presenting equally viable explanations for some or all of the observed SN Ia host bias.

  7. The VLT-FLAMES survey of massive stars: rotation and nitrogen enrichment as the key to understanding massive star evolution

    E-Print Network [OSTI]

    I. Hunter; I. Brott; D. J. Lennon; N. Langer; P. L. Dufton; C. Trundle; S. J. Smartt; A. de Koter; C. J. Evans; R. S. I. Ryans


    Rotation has become an important element in evolutionary models of massive stars, specifically via the prediction of rotational mixing. Here, we study a sample of stars, including rapid rotators, to constrain such models and use nitrogen enrichments as a probe of the mixing process. Chemical compositions (C, N, O, Mg and Si) have been estimated for 135 early B-type stars in the Large Magellanic Cloud with projected rotational velocities up to ~300km/s using a non-LTE TLUSTY model atmosphere grid. Evolutionary models, including rotational mixing, have been generated attempting to reproduce these observations by adjusting the overshooting and rotational mixing parameters and produce reasonable agreement with 60% of our core hydrogen burning sample. We find (excluding known binaries) a significant population of highly nitrogen enriched intrinsic slow rotators vsini less than 50km/s incompatible with our models ~20% of the sample). Furthermore, while we find fast rotators with enrichments in agreement with the models, the observation of evolved (log g less than 3.7dex) fast rotators that are relatively unenriched (a further ~20% of the sample) challenges the concept of rotational mixing. We also find that 70% of our blue supergiant sample cannot have evolved directly from the hydrogen burning main-sequence. We are left with a picture where invoking binarity and perhaps fossil magnetic fields are required to understand the surface properties of a population of massive main sequence stars.

  8. Metallicities of M Dwarf Planet Hosts from Spectral Synthesis

    E-Print Network [OSTI]

    Jacob L. Bean; G. Fritz Benedict; Michael Endl


    We present the first spectroscopic metallicities of three M dwarfs with known or candidate planetary mass companions. We have analyzed high resolution, high signal-to-noise spectra of these stars which we obtained at McDonald Observatory. Our analysis technique is based on spectral synthesis of atomic and molecular features using recently revised cool-star model atmospheres and spectrum synthesis code. The technique has been shown to yield results consistent with the analyses of solar-type stars and allows measurements of M dwarf [M/H] values to 0.12 dex precision. From our analysis, we find [M/H] = -0.12, -0.32, and -0.33 for GJ 876, GJ 436, and GJ 581 respectively. These three M dwarf planet hosts have sub-solar metallicities, a surprising departure from the trend observed in FGK-type stars. This study is the first part of our ongoing work to determine the metallicities of the M dwarfs included in the McDonald Observatory planet search program.


    SciTech Connect (OSTI)

    Fuhrmann, Klaus [Astronomisches Institut, Ruhr-Universitaet Bochum, Universitaetsstrasse 150, D-44780 Bochum (Germany)


    This work presents the first quantitative composite model atmosphere analysis of Capella, the brightest near-equal-mass spectroscopic binary and principal star of the constellation Auriga. Its high-resolution spectrum leads to a slightly metal-rich object at [Fe/H] = +0.05 {+-} 0.08 dex. In line with its young age and its kinematics, this consistently associates Capella with the Hyades moving group. The measured projected rotational velocities, vsin i{sub Aa} = 3.5 {+-} 0.8 km s{sup -1} and vsin i{sub Ab} = 35.4 {+-} 3.2 km s{sup -1}, both agree with rotational and orbital coplanarity and synchronous orbital rotation for the Aa component. At an orbital period P = 104 d the primary's bound rotation together with the almost zero orbital eccentricity are both key characteristics of this binary and clearly imply that the Aa component must have passed the tip of the giant branch. Whether in that phase Capella also became a mass transfer system remains inconclusive at present, though the high rotational velocity of the less evolved Hertzsprung gap secondary and the very diverse lithium abundances of both its components render this a plausible case.

  10. Thorium-rich halo star HD221170: further evidence against the universality of the r-process

    E-Print Network [OSTI]

    Alexander Yushchenko; Vera Gopka; Stephane Goriely; Faig Musaev; Angelina Shavrina; Chulhee Kim; Young Woon Kang; Juliana Kuznietsova; Vladimir Yushchenko


    We report the abundance determination in the atmosphere of the bright halo star HD221170. The spectra were taken with the Terskol Observatory's 2.0-m telescope with a resolution R=45000 and signal-to-noise ratio up to 250 in the wavelength region 3638-10275 \\AA. The adopted atmospheric parameters correspond to an effective temperature \\Tef=4475 K, a surface gravity \\lgg=1.0, a microturbulent velocity \\vmi=1.7 \\kms, and a macroturbulent velocity \\vma=4 \\kms. The abundances of 43 chemical elements were determined with the method of spectrum synthesis. The large overabundances (by 1 dex relative to iron) of elements with Z$>38$ are shown to follow the same pattern as the solar r-abundances. The present HD221170 analysis confirms the non-universality of the r-process, or more exactly the observation that the astrophysical sites hosting the r-process do not always lead to a unique relative abundance distribution for the bulk Ba to Hg elements, the Pb-peak elements, and the actinides.

  11. Stellar loci III: Photometric metallicities for half million FGK stars of Stripe 82

    E-Print Network [OSTI]

    Yuan, Haibo; Xiang, Maosheng; Huang, Yang; Chen, Bingqiu


    We develop a method to estimate photometric metallicities by simultaneously fitting the dereddened colors u-g, g-r, r-i and i-z from the SDSS with those predicted by the metallicity-dependent stellar loci. The method is tested with a spectroscopic sample of main-sequence stars in Stripe 82 selected from the SDSS DR9 and three open clusters. With 1 per cent photometry, the method is capable of delivering photometric metallicities precise to about 0.05, 0.12, and 0.18 dex at metallicities of 0.0, -1.0, and -2.0, respectively, comparable to the precision achievable with low-resolution spectroscopy at a signal-to-noise ratio of 10. We apply this method to the re-calibrated Stripe 82 catalog and derive metallicities for about 0.5 million stars of colors 0.3 < g-i < 1.6 mag and distances between 0.3 -- 18 kpc. Potential systematics in the metallicities thus derived, due to the contamination of giants and binaries, are investigated. Photometric distances are also calculated. About 91, 72, and 53 per cent of th...

  12. On the solar nickel and oxygen abundances

    E-Print Network [OSTI]

    Pat Scott; Martin Asplund; Nicolas Grevesse; A. Jacques Sauval


    Determinations of the solar oxygen content relying on the neutral forbidden transition at 630 nm depend upon the nickel abundance, due to a Ni I blend. Here we rederive the solar nickel abundance, using the same ab initio 3D hydrodynamic model of the solar photosphere employed in the recent revision of the abundances of C, N, O and other elements. Using 17 weak, unblended lines of Ni I together with the most accurate atomic and observational data available we find log epsilon_Ni = 6.17 +/- 0.02 (statistical) +/- 0.05 (systematic), a downwards shift of 0.06 to 0.08 dex relative to previous 1D-based abundances. We investigate the implications of the new nickel abundance for studies of the solar oxygen abundance based on the [O I] 630 nm line in the quiet Sun. Furthermore, we demonstrate that the oxygen abundance implied by the recent sunspot spectropolarimetric study of Centeno & Socas-Navarro needs to be revised downwards from log epsilon_O = 8.86 +/- 0.07 to 8.71 +/- 0.10. This revision is based on the new nickel abundance, application of the best available gf-value for the 630 nm forbidden oxygen line, and a more transparent treatment of CO formation. Determinations of the solar oxygen content relying on forbidden lines now appear to converge around log epsilon_O = 8.7.

  13. Operators Manual and Technical Reference for the Z-Beamlet Phase Modulation Failsafe System: Version 1.

    SciTech Connect (OSTI)

    Armstrong, Darrell J.


    The need for pulse energies exceeding 4 kJ and pulse lengths [?] 2 ns in Sandia's Z-Beamlet laser (ZBL) requires that the single-frequency spectrum of its fiber-laser master oscillator be converted to a phase modulated spectrum with a modulation in dex [?] 5. Because accidental injection of single-frequency light into ZBL could result i n damage to optical materials from transverse stimulated Brillouin scattering, the presence of phase modulated (PM) light must be monitored by a reliable failsafe system that can stop a las er shot within of a few 10's of ns following a failure of the PM system. This requirement is met by combining optical heterodyne detection with high-speed electronics to indicate the pres ence or absence of phase modulated light. The transition time for the failsafe signal resultin g from a sudden failure using this technique is approximately 35 ns. This is sufficiently short to safely stop a single-frequency laser pulse from leaving ZBL's regenerative amplifier with a n approximately 35 ns margin of safety. This manual and technical reference contains detai led instructions for daily use of the PM failsafe system and provides enough additional informat ion for its maintenance and repair.

  14. Growth of Spirals: Secular or Driven by Mergers ?

    E-Print Network [OSTI]

    F. Hammer


    The physical phenomena contributing to the galaxy growth can be tested all the way to z= 1. Galaxy mass, extinction, star formation and gas metal abundance can be measured in a robust way, as well as the distribution of the galaxy morphologies. I discuss here the observational methods and their accuracy. Physical quantities can be evaluated with uncertainties much lower than 0.3 dex, if they are based on 2 sets of independent measurements. For example, at a given IMF, the star formation rate is well estimated by combining flux measurements of the extinction corrected Balmer line and of the mid-IR continuum. Spiral mass growth had occurred from gas accretion and from merging. Gas accretion can explain at most half of the spiral mass growth: at moderate redshift, the numerous population of compact, merger and irregular galaxies requires another origin. A spiral rebuilding scenario is able to reproduce all the evolutionary trends observed since z~1, and could be at the origin of the present-day, numerous population of early type spirals.


    E-Print Network [OSTI]

    Paris-Sud XI, Universit de

    253 EXPRIENCES SUR LA DCHARGE DISRUPTIVE FAITES AVEC LA PILE AU CHLORURE D'ARGENT ; PAR MM rsultats d'ex- priences faites avec la pile constante chlorure d'argent. La pile , dont nous nous sommes- veaux prts tre chargs, ce qui fera un total de 1 i ooo. Cette pile est dispose par sries de 20

  16. Vendredi 23 mai 2008 Il y a pnurie de gologues sur un march

    E-Print Network [OSTI]

    Schibler, Ueli

    matires premires mi- nrales telles que le fer, le cuivre, le zinc ou l'uranium. En raison de la Fontbot. Un grand nombre de compagnies d'exploration et d'ex- ploitation d'hydrocarbures et de minerais se de l'exploration mi- nire et Canadian Environmental and Metallurgical (CEMI), spcia- liste du

  17. We determined basic stellar parameters and the chemical abundances of a small sample of 15 hot, H-rich post-AGB stars using high-resolution, high-

    E-Print Network [OSTI]

    Barnstedt, Jürgen

    stages of post-AGB stellar evolution. Spectral analysis The photospheric model spectral energy of Science Institute for Astronomy and Astrophysics Acknowledgements TR is supported by the German Aerospace] denotes log [mass fraction / solar mass fraction]. The typical error is 0.3 dex. Table 1: Parameters


    SciTech Connect (OSTI)

    Richter, Philipp; Fechner, Cora [Institut fuer Physik und Astronomie, Universitaet Potsdam, Haus 28, Karl-Liebknecht-Str. 24/25, D-14476 Golm (Potsdam) (Germany); Fox, Andrew J. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Wakker, Bart P. [Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706 (United States); Lehner, Nicolas; Howk, J. Christopher [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Bland-Hawthorn, Joss [Institute of Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Ben Bekhti, Nadya [Argelander-Institut fuer Astronomie, Universitaet Bonn, Auf dem Huegel 71, D-53121 Bonn (Germany)


    We present a multi-wavelength study of the Magellanic Stream (MS), a massive gaseous structure in the Local Group that is believed to represent material stripped from the Magellanic Clouds. We use ultraviolet, optical and radio data obtained with HST/COS, VLT/UVES, FUSE, GASS, and ATCA to study metal abundances and physical conditions in the Stream toward the quasar Fairall 9. Line absorption in the MS from a large number of metal ions and from molecular hydrogen is detected in up to seven absorption components, indicating the presence of multi-phase gas. From the analysis of unsaturated S II absorption, in combination with a detailed photoionization model, we obtain a surprisingly high {alpha} abundance in the Stream toward Fairall 9 of [S/H] = -0.30 {+-} 0.04 (0.50 solar). This value is five times higher than what is found along other MS sightlines based on similar COS/UVES data sets. In contrast, the measured nitrogen abundance is found to be substantially lower ([N/H] = -1.15 {+-} 0.06), implying a very low [N/{alpha}] ratio of -0.85 dex. The substantial differences in the chemical composition of MS toward Fairall 9 compared to other sightlines point toward a complex enrichment history of the Stream. We favor a scenario, in which the gas toward Fairall 9 was locally enriched with {alpha} elements by massive stars and then was separated from the Magellanic Clouds before the delayed nitrogen enrichment from intermediate-mass stars could set in. Our results support (but do not require) the idea that there is a metal-enriched filament in the Stream toward Fairall 9 that originates in the LMC.


    SciTech Connect (OSTI)

    Cortes, C.; Do Nascimento, J. D.; De Medeiros, J. R. [Departamento de Fisica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Silva, J. R. P. [Departamento de Fisica, Universidade do Estado do Rio Grande do Norte, Mossoro, RN (Brazil); Recio-Blanco, A. [Observatoire de la Cote d'Azur, Nice (France); Catelan, M. [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Santiago (Chile)


    This paper describes the behavior of the rotational velocity in metal-poor stars ([Fe/H] <= -0.5 dex) in different evolutionary stages, based on vsin i values from the literature. Our sample is comprised of stars in the field and some Galactic globular clusters, including stars on the main sequence, the red giant branch (RGB), and the horizontal branch (HB). The metal-poor stars are, mainly, slow rotators, and their vsin i distribution along the HR diagram is quite homogeneous. Nevertheless, a few moderate to high values of vsin i are found in stars located on the main sequence and the HB. We show that the overall distribution of vsin i values is basically independent of metallicity for the stars in our sample. In particular, the fast-rotating main sequence stars in our sample present rotation rates similar to their metal-rich counterparts, suggesting that some of them may actually be fairly young, in spite of their low metallicity, or else that at least some of them would be better classified as blue straggler stars. We do not find significant evidence of evolution in vsin i values as a function of position on the RGB; in particular, we do not confirm previous suggestions that stars close to the RGB tip rotate faster than their less-evolved counterparts. While the presence of fast rotators among moderately cool blue HB stars has been suggested to be due to angular momentum transport from a stellar core that has retained significant angular momentum during its prior evolution, we find that any such transport mechanisms most likely operate very fast as the star arrives on the zero-age HB (ZAHB), since we do not find a link between evolution off the ZAHB and vsin i values. We present an extensive tabulation of all quantities discussed in this paper, including rotation velocities, temperatures, gravities, and metallicities [Fe/H], as well as broadband magnitudes and colors.

  20. Spectroscopic metallicities for Fornax UCDs, GCs and dE,Ns

    E-Print Network [OSTI]

    S. Mieske; M. Hilker; L. Infante; A. Jordan


    Various formation channels for the puzzling ultra-compact dwarf galaxies (UCDs) have been proposed in the last few years. To better judge on some of the competing scenarios, we present spectroscopic [Fe/H] estimates for a sample of 26 compact objects in the central region of the Fornax cluster, covering the magnitude range of UCDs and bright globular clusters. We find a break in the metallicity distribution of compact objects at M_V ~ -11 mag (~3*10^6 M_sun): for M_V-11 mag. This metallicity break is accompanied by a change in the size-luminosity relation for compact objects, as deduced from HST-imaging: for M_V-11 mag, r_h is almost luminosity-independent. We therefore assume a limiting absolute magnitude of M_V=-11 mag between UCDs and globular clusters. The mean metallicity of five Fornax dE,N nuclei included in our study is about 0.8 dex lower than that of the UCDs, at 4.5 sigma significance. Because of this large metallicity discrepancy we disfavor the hypothesis that most of the Fornax UCDs are the remnant nuclei of tidally stripped dE,Ns. Our metallicity estimates for UCDs are closer to but slightly below those derived for young massive clusters (YMCs) of comparable masses. We therefore favor a scenario where most UCDs in Fornax are successors of merged YMCs produced in the course of violent galaxy-galaxy mergers. It is noted that in contrast to that, the properties of Virgo UCDs are more consistent with the stripping scenario, suggesting that different UCD formation channels may dominate in either cluster.

  1. The solar photospheric abundance of hafnium and thorium. Results from CO5BOLD 3D hydrodynamic model atmospheres

    E-Print Network [OSTI]

    Elisabetta Caffau; L. Sbordone; H. -G. Ludwig; P. Bonifacio; M. Steffen; N. T. Behara


    Context: The stable element hafnium (Hf) and the radioactive element thorium (Th) were recently suggested as a suitable pair for radioactive dating of stars. The applicability of this elemental pair needs to be established for stellar spectroscopy. Aims: We aim at a spectroscopic determination of the abundance of Hf and Th in the solar photosphere based on a \\cobold 3D hydrodynamical model atmosphere. We put this into a wider context by investigating 3D abundance corrections for a set of G- and F-type dwarfs. Method: High-resolution, high signal-to-noise solar spectra were compared to line synthesis calculations performed on a solar CO5BOLD model. For the other atmospheres, we compared synthetic spectra of CO5BOLD 3D and associated 1D models. Results: For Hf we find a photospheric abundance A(Hf)=0.87+-0.04, in good agreement with a previous analysis, based on 1D model atmospheres. The weak Th ii 401.9 nm line constitutes the only Th abundance indicator available in the solar spectrum. It lies in the red wing of an Ni-Fe blend exhibiting a non-negligible convective asymmetry. Accounting for the asymmetry-related additional absorption, we obtain A(Th)=0.09+-0.03, consistent with the meteoritic abundance, and about 0.1 dex lower than obtained in previous photospheric abundance determinations. Conclusions: Only for the second time, to our knowledge, has am non-negligible effect of convective line asymmetries on an abundance derivation been highlighted. Three-dimensional hydrodynamical simulations should be employed to measure Th abundances in dwarfs if similar blending is present, as in the solar case. In contrast, 3D effects on Hf abundances are small in G- to mid F-type dwarfs and sub-giants, and 1D model atmospheres can be conveniently used.


    SciTech Connect (OSTI)

    Johnson, Benjamin D. [Institute d'Astrophysique de Paris, CNRS, UPMC, 98bis Bd Arago, F-75014 Paris (France); Weisz, Daniel R.; Dalcanton, Julianne J.; Johnson, L. C.; Williams, Benjamin F. [Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States); Dale, Daniel A. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Dolphin, Andrew E. [Raytheon, 1151 E. Hermans Road, Tucson, AZ 85756 (United States); Gil de Paz, Armando [CEI Campus Moncloa, UCM-UPM, Departamento de Astrofisica y CC. de la Atmosfera, Facultad de CC. Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain); Kennicutt, Robert C. Jr. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Lee, Janice C. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Skillman, Evan D. [Department of Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Boquien, Mederic [Marseille Universite, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, F-13388 Marseille (France)


    We use empirical star formation histories (SFHs), measured from Hubble-Space-Telescope-based resolved star color-magnitude diagrams, as input into population synthesis codes to model the broadband spectral energy distributions (SEDs) of 50 nearby dwarf galaxies (6.5 < log M{sub *}/M{sub Sun} < 8.5, with metallicities {approx}10% solar). In the presence of realistic SFHs, we compare the modeled and observed SEDs from the ultraviolet (UV) through near-infrared and assess the reliability of widely used UV-based star formation rate (SFR) indicators. In the FUV through i bands, we find that the observed and modeled SEDs are in excellent agreement. In the Spitzer 3.6 {mu}m and 4.5 {mu}m bands, we find that modeled SEDs systematically overpredict observed luminosities by up to {approx}0.2 dex, depending on treatment of the TP-AGB stars in the synthesis models. We assess the reliability of UV luminosity as a SFR indicator, in light of independently constrained SFHs. We find that fluctuations in the SFHs alone can cause factor of {approx}2 variations in the UV luminosities relative to the assumption of a constant SFH over the past 100 Myr. These variations are not strongly correlated with UV-optical colors, implying that correcting UV-based SFRs for the effects of realistic SFHs is difficult using only the broadband SED. Additionally, for this diverse sample of galaxies, we find that stars older than 100 Myr can contribute from <5%-100% of the present day UV luminosity, highlighting the challenges in defining a characteristic star formation timescale associated with UV emission. We do find a relationship between UV emission timescale and broadband UV-optical color, though it is different than predictions based on exponentially declining SFH models. Our findings have significant implications for the comparison of UV-based SFRs across low-metallicity populations with diverse SFHs.

  3. Discovery of a peculiar Cepheid-like star towards the northern edge of the Small Magellanic Cloud

    E-Print Network [OSTI]

    J. B. Marquette; P. Tisserand; P. Francois; J. P. Beaulieu; V. Doublier; E. Lesquoy; A. Milsztajn; J. Pritchard; A. Schwarzenberg-Czerny; C. Afonso; J. N. Albert; J. Andersen; R. Ansari; E. Aubourg; P. Bareyre; X. Charlot; C. Coutures; R. Ferlet; P. Fouque; J. F. Glicenstein; B. Goldman; A. Gould; D. Graff; M. Gros; J. Haissinski; C. Hamadache; J. de Kat; L. Le Guillou; C. Loup; C. Magneville; E. Maurice; A. Maury; M. Moniez; N. Palanque-Delabrouille; O. Perdereau; Y. R. Rahal; J. Rich; M. Spiro; A. Vidal-Madjar; S. Zylberajch


    For seven years, the EROS-2 project obtained a mass of photometric data on variable stars. We present a peculiar Cepheid-like star, in the direction of the Small Magellanic Cloud, which demonstrates unusual photometric behaviour over a short time interval. We report on data of the photometry acquired by the MARLY telescope and spectroscopy from the EFOSC instrument for this star, called EROS2 J005135-714459(sm0060n13842), which resembles the unusual Cepheid HR 7308. The light curve of our target is analysed using the Analysis of Variance method to determine a pulsational period of 5.5675 days. A fit of time-dependent Fourier coefficients is performed and a search for proper motion is conducted. The light curve exhibits a previously unobserved and spectacular change in both mean magnitude and amplitude, which has no clear theoretical explanation. Our analysis of the spectrum implies a radial velocity of 104 km s$^{-1}$ and a metallicity of -0.4$\\pm$0.2 dex. In the direction of right ascension, we measure a proper motion of 17.4$\\pm$6.0 mas yr$^{-1}$ using EROS astrometry, which is compatible with data from the NOMAD catalogue. The nature of EROS2 J005135-714459(sm0060n13842) remains unclear. For this star, we may have detected a non-zero proper motion for this star, which would imply that it is a foreground object. Its radial velocity, pulsational characteristics, and photometric data, however, suggest that it is instead a Cepheid-like object located in the SMC. In such a case, it would present a challenge to conventional Cepheid models.


    SciTech Connect (OSTI)

    Reep, J. W.; Bradshaw, S. J. [Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States)] [Department of Physics and Astronomy, Rice University, Houston, TX 77005 (United States); Klimchuk, J. A., E-mail:, E-mail:, E-mail: [NASA Goddard Space Flight Center, Solar Physics Lab., Code 671, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States)


    The time dependence of heating in solar active regions can be studied by analyzing the slope of the emission measure distribution coolward of the peak. In a previous study we showed that low-frequency heating can account for 0% to 77% of active region core emission measures. We now turn our attention to heating by a finite succession of impulsive events for which the timescale between events on a single magnetic strand is shorter than the cooling timescale. We refer to this scenario as a 'nanoflare train' and explore a parameter space of heating and coronal loop properties with a hydrodynamic model. Our conclusions are (1) nanoflare trains are consistent with 86% to 100% of observed active region cores when uncertainties in the atomic data are properly accounted for; (2) steeper slopes are found for larger values of the ratio of the train duration {Delta} {sub H} to the post-train cooling and draining timescale {Delta} {sub C}, where {Delta} {sub H} depends on the number of heating events, the event duration and the time interval between successive events ({tau} {sub C}); (3) {tau} {sub C} may be diagnosed from the width of the hot component of the emission measure provided that the temperature bins are much smaller than 0.1 dex; (4) the slope of the emission measure alone is not sufficient to provide information about any timescale associated with heating-the length and density of the heated structure must be measured for {Delta} {sub H} to be uniquely extracted from the ratio {Delta} {sub H}/{Delta} {sub C}.

  5. Fundamental Parameters and Abundances of Metal-Poor Stars: The SDSS Standard BD +17 4708

    E-Print Network [OSTI]

    I. Ramirez; C. Allende Prieto; S. Redfield; D. L. Lambert


    The atmospheric parameters and iron abundance of the Sloan Digital Sky Survey (SDSS) spectrophotometric standard star BD +17 4708 are critically examined using up-to-date Kurucz model atmospheres, LTE line formation calculations, and reliable atomic data. We find Teff = 6141+-50 K, log g = 3.87+-0.08, and [Fe/H]=-1.74+-0.09. The line-of-sight interstellar reddening, bolometric flux, limb-darkened angular diameter, stellar mass, and the abundances of Mg, Si, and Ca are also obtained. This star is a unique example of a moderately metal-poor star for which the effective temperature can be accurately constrained from the observed spectral energy distribution (corrected for reddening). Such analysis leads to a value that is higher than most spectroscopic results previously reported in the literature (~5950 K). We find that the ionization balance of Fe lines is satisfied only if a low Teff (~5950 K) is adopted. With our preferred Teff (6141 K), the mean iron abundance we obtain from the FeII lines is lower by about 0.15 dex than that from the FeI lines, and therefore, the discrepancy between the mean iron abundance from FeI and FeII lines cannot be explained by overionization by UV photons as the main non-LTE effect. We also comment on non-LTE effects and the importance of inelastic collisions with neutral H atoms in the determination of oxygen abundances in metal-poor stars from the 777 nm OI triplet. (Abridged)


    SciTech Connect (OSTI)

    Treu, Tommaso; Gavazzi, Raphael; Gorecki, Alexia; Marshall, Philip J. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Koopmans, Leon V. E. [Kapteyn Institute, P.O. Box 800, 9700AV Groningen (Netherlands); Bolton, Adam S. [Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Dr., Honolulu, HI 96822 (United States); Moustakas, Leonidas A. [Jet Propulsion Laboratory, 4800 Oak Grove Dr, Caltech, MS169-327, Pasadena, CA 91109 (United States); Burles, Scott [Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)], E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:


    We study the relation between the internal structure of early-type galaxies and their environment using 70 strong gravitational lenses from the SLACS Survey. The Sloan Digital Sky Survey (SDSS) database is used to determine two measures of overdensity of galaxies around each lens-the projected number density of galaxies inside the tenth nearest neighbor ({sigma}{sub 10}) and within a cone of radius one h{sup -1} Mpc (D {sub 1}). Our main results are as follows. (1) The average overdensity is somewhat larger than unity, consistent with lenses preferring overdense environments as expected for massive early-type galaxies (12/70 lenses are in known groups/clusters). (2) The distribution of overdensities is indistinguishable from that of 'twin' nonlens galaxies selected from SDSS to have the same redshift and stellar velocity dispersion {sigma}{sub *}. Thus, within our errors, lens galaxies are an unbiased population, and the SLACS results can be generalized to the overall population of early-type galaxies. (3) Typical contributions from external mass distribution are no more than a few percent in local mass density, reaching 10-20% ({approx}0.05-0.10 external convergence) only in the most extreme overdensities. (4) No significant correlation between overdensity and slope of the mass-density profile of the lens galaxies is found. (5) Satellite galaxies (those with a more luminous companion) have marginally steeper mass-density profiles (as quantified by f {sub SIE} = {sigma}{sub *}/{sigma}{sub SIE} = 1.12 {+-} 0.05 versus 1.01 {+-} 0.01) and smaller dynamically normalized mass enclosed within the Einstein radius ({delta}log M {sub Ein}/M {sub dim} differs by -0.09 {+-} 0.03 dex) than central galaxies (those without). This result suggests that tidal stripping may affect the mass structure of early-type galaxies down to kpc scales probed by strong lensing, when they fall into larger structures.


    SciTech Connect (OSTI)

    Lo Faro, B.; Franceschini, A.; Vaccari, M.; Rodighiero, G.; Feltre, A.; Marchetti, L. [Dipartimento di Fisica e Astronomia, Universita di Padova, vicolo Osservatorio, 3, I-35122 Padova (Italy)] [Dipartimento di Fisica e Astronomia, Universita di Padova, vicolo Osservatorio, 3, I-35122 Padova (Italy); Silva, L. [INAF-OATs, Via Tiepolo 11, I-34131 Trieste (Italy)] [INAF-OATs, Via Tiepolo 11, I-34131 Trieste (Italy); Berta, S.; Lutz, D.; Magnelli, B. [MPE, Postfach 1312, D-85741, Garching (Germany)] [MPE, Postfach 1312, D-85741, Garching (Germany); Bock, J. [California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States)] [California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Burgarella, D.; Buat, V. [Laboratoire d'Astrophysique de Marseille, OAMP, Universite Aix-Marseille, CNRS, 38 rue Frederic Joliot-Curie, F-13388 Marseille Cedex 13 (France)] [Laboratoire d'Astrophysique de Marseille, OAMP, Universite Aix-Marseille, CNRS, 38 rue Frederic Joliot-Curie, F-13388 Marseille Cedex 13 (France); Cava, A. [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)] [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Clements, D. L. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom)] [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Cooray, A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States)] [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Farrah, D.; Hurley, P. [Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom)] [Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Solares, E. A. Gonzalez [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)] [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Magdis, G., E-mail: [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); and others


    We combine far-infrared photometry from Herschel (PEP/HerMES) with deep mid-infrared spectroscopy from Spitzer to investigate the nature and the mass assembly history of a sample of 31 luminous and ultraluminous infrared galaxies ((U)LIRGs) at z {approx} 1 and 2 selected in GOODS-S with 24 {mu}m fluxes between 0.2 and 0.5 mJy. We model the data with a self-consistent physical model (GRASIL) which includes a state-of-the-art treatment of dust extinction and reprocessing. We find that all of our galaxies appear to require massive populations of old (>1 Gyr) stars and, at the same time, to host a moderate ongoing activity of star formation (SFR {<=} 100 M {sub Sun} yr{sup -1}). The bulk of the stars appear to have been formed a few Gyr before the observation in essentially all cases. Only five galaxies of the sample require a recent starburst superimposed on a quiescent star formation history. We also find discrepancies between our results and those based on optical-only spectral energy distribution (SED) fitting for the same objects; by fitting their observed SEDs with our physical model we find higher extinctions (by {Delta}A {sub V} {approx} 0.81 and 1.14) and higher stellar masses (by {Delta}log(M {sub *}) {approx} 0.16 and 0.36 dex) for z {approx} 1 and z {approx} 2 (U)LIRGs, respectively. The stellar mass difference is larger for the most dust-obscured objects. We also find lower SFRs than those computed from L {sub IR} using the Kennicutt relation due to the significant contribution to the dust heating by intermediate-age stellar populations through 'cirrus' emission ({approx}73% and {approx}66% of the total L {sub IR} for z {approx} 1 and z {approx} 2 (U)LIRGs, respectively).


    SciTech Connect (OSTI)

    Rao, S. Sumangala; Pandey, Gajendra; Giridhar, Sunetra [Indian Institute of Astrophysics, Bengaluru-560034 (India); Lambert, David L., E-mail:, E-mail:, E-mail:, E-mail: [W. J. McDonald Observatory, University of Texas, Austin, TX 78712 (United States)


    We have conducted an LTE abundance analysis for SAO 40039, a warm post-AGB star whose spectrum is known to show surprisingly strong He I lines for its effective temperature and has been suspected of being H-deficient and He-rich. High-resolution optical spectra are analyzed using a family of model atmospheres with different He/H ratios. Atmospheric parameters are estimated from the ionization equilibrium set by neutral and singly ionized species of Fe and Mg, the excitation of Fe I and Fe II lines, and the wings of the Paschen lines. On the assumption that the He I lines are of photospheric and not chromospheric origin, a He/H ratio of approximately unity is found by imposing the condition that the adopted He/H ratio of the model atmosphere must equal the ratio derived from the observed He I triplet lines at 5876, 4471, and 4713 A, and singlet lines at 4922 and 5015 A. Using the model with the best-fitting atmospheric parameters for this He/H ratio, SAO 40039 is confirmed to exhibit mild dust-gas depletion, i.e., the star has an atmosphere deficient in elements of high condensation temperature. The star appears to be moderately metal-deficient with [Fe/H] = -0.4 dex. But the star's intrinsic metallicity as estimated from Na, S, and Zn, elements of a low condensation temperature, is [Fe/H]{sub o} {approx_equal} -0.2 ([Fe/H]{sub o} refers to the star's intrinsic metallicity). The star is enriched in N and perhaps O as well, changes reflecting the star's AGB past and the event that led to He enrichment.

  9. Chemical Properties of Star-Forming Emission Line Galaxies at z=0.1 - 0.5

    E-Print Network [OSTI]

    Henry A. Kobulnicky; Dennis Zaritsky


    We measure oxygen and nitrogen abundances for 14 star-forming emission line galaxies (ELGs) at 0.110.5 using Keck/LRIS optical spectroscopy. The targets exhibit a range of metallicities from slightly metal-poor like the LMC to super-solar. Oxygen abundances of the sample correlate strongly with rest-frame blue luminosities. The metallicity-luminosity relation based on these 14 objects is indistinguishable from the one obeyed by local galaxies, although there is marginal evidence (1.1sigma) that the sample is slightly more metal-deficient than local galaxies of the same luminosity. The observed galaxies exhibit smaller emission linewidths than local galaxies of similar metallicity, but proper corrections for inclination angle and other systematic effects are unknown. For 8 of the 14 objects we measure nitrogen-to-oxygen ratios. Seven of 8 systems show evidence for secondary nitrogen production, with log(N/O)> -1.4 like local spirals. These chemical properties are inconsistent with unevolved objects undergoing a first burst of star formation. The majority of the ELGs are presently ~4 magnitudes brighter and ~0.5 dex more metal-rich than the bulk of the stars in well-known metal-poor dwarf spheroidals such as NGC 205 and NGC 185, making an evolution between some ELGs and metal-poor dwarf spheroidals improbable. However, the data are consistent with the hypothesis that more luminous and metal-rich spheroidal galaxies like NGC 3605 may become the evolutionary endpoints of some ELGs. [abridged


    SciTech Connect (OSTI)

    Do Nascimento, J.-D. Jr.; Da Costa, J. S.; Castro, M. [Departamento de Fisica Teorica e Experimental (DFTE), Universidade Federal do Rio Grande do Norte (UFRN), CP 1641, 59072-970 Natal, RN (Brazil); Takeda, Y. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Melendez, J. [Departamento de Astronomia do IAG/USP, Universidade de Sao Paulo, Rua do Matao 1226, 05508-900 Sao Paulo, SP (Brazil); Porto de Mello, G. F., E-mail: [Observatrio do Valongo, UFRJ, Ladeira do Pedro Antonio 43, 20080-090 Rio de Janeiro, RJ (Brazil)


    The question of whether the Sun is peculiar within the class of solar-type stars has been the subject of active investigation over the past three decades. Although several solar twins have been found with stellar parameters similar to those of the Sun (albeit in a range of Li abundances and with somewhat different compositions), their rotation periods are unknown, except for 18 Sco, which is younger than the Sun and with a rotation period shorter than solar. It is difficult to obtain rotation periods for stars of solar age from ground-based observations, as a low-activity level implies a shallow rotational modulation of their light curves. CoRoT has provided space-based long time series from which the rotation periods of solar twins as old as the Sun could be estimated. Based on high-signal-to-noise, high-resolution spectroscopic observations gathered at the Subaru Telescope, we show that the star CoRoT ID 102684698 is a somewhat evolved solar twin with a low Li abundance. Its rotation period is 29 {+-} 5 days, compatible with its age (6.7 Gyr) and low lithium content, A{sub Li} {approx}< 0.85 dex. Interestingly, our CoRoT solar twin seems to have enhanced abundances of the refractory elements with respect to the Sun, a typical characteristic of most nearby twins. With a magnitude V {approx_equal} 14.1, ID 102684698 is the first solar twin revealed by CoRoT, the farthest field solar twin so far known, and the only solar twin older than the Sun for which a rotation period has been determined.


    SciTech Connect (OSTI)

    Lee, Young Sun; Beers, Timothy C. [Department of Physics and Astronomy and JINA (Joint Institute for Nuclear Astrophysics), Michigan State University, East Lansing, MI 48824 (United States); Prieto, Carlos Allende [Instituto de Astrofisica de Canarias, E-38205 La Laguna, Tenerife (Spain); Lai, David K.; Rockosi, Constance M. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Morrison, Heather L. [Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106 (United States); Johnson, Jennifer A. [Department of Astronomy, Ohio State University, Columbus, OH 43210 (United States); An, Deokkeun [Department of Science Education, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Sivarani, Thirupathi [Indian Institute of Astrophysics, 2nd block Koramangala, Bangalore 560034 (India); Yanny, Brian, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail:, E-mail: [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)


    We present a method for the determination of [{alpha}/Fe] ratios from low-resolution (R = 2000) SDSS/SEGUE stellar spectra. By means of a star-by-star comparison with degraded spectra from the ELODIE spectral library and with a set of moderately high-resolution (R = 15, 000) and medium-resolution (R = 6000) spectra of SDSS/SEGUE stars, we demonstrate that we are able to measure [{alpha}/Fe] from SDSS/SEGUE spectra (with S/N>20/1) to a precision of better than 0.1 dex, for stars with atmospheric parameters in the range T{sub eff} = [4500, 7000] K, log g = [1.5, 5.0], and [Fe/H] = [-1.4, +0.3], over the range [{alpha}/Fe] = [-0.1, +0.6]. For stars with [Fe/H] <-1.4, our method requires spectra with slightly higher signal-to-noise to achieve this precision (S/N>25/1). Over the full temperature range considered, the lowest metallicity star for which a confident estimate of [{alpha}/Fe] can be obtained from our approach is [Fe/H] {approx}-2.5; preliminary tests indicate that a metallicity limit as low as [Fe/H] {approx}-3.0 may apply to cooler stars. As a further validation of this approach, weighted averages of [{alpha}/Fe] obtained for SEGUE spectra of likely member stars of Galactic globular clusters (M15, M13, and M71) and open clusters (NGC 2420, M67, and NGC 6791) exhibit good agreement with the values of [{alpha}/Fe] from previous studies. The results of the comparison with NGC 6791 imply that the metallicity range for the method may extend to {approx}+0.5.

  12. Multicommodity formulations for the prize collecting vehicle routing

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    wells are pumped using artificial lift systems. One such system is the Mobile Oil Recovery (MOR) unit. The MOR unit is an artificial lift system which is used to exploit wells whose production is marginal, multiobjective. R´esum´e Les unit´es mobiles de pompage sont des camions munis d'un syst`eme d'ex- traction de p

  13. Hydrocarbon in Catalyst in

    E-Print Network [OSTI]

    Ladkin, Peter B.

    Hydrocarbon in Steam in Catalyst in Vent 1 Vent 2 Product out Tank Pressure #12;#12;#12;#12;#12;#12;#12;#12;Hydrocarbon in Steam in Catalyst in Vent 1 Vent 2 Product out Tank Pressure controller Computer operator

  14. Hydrocarbon in Catalyst in

    E-Print Network [OSTI]

    Ladkin, Peter B.

    #12;Hydrocarbon in Steam in Catalyst in Vent 1 Vent 2 Product out Tank Pressure controller Computer;#12;Vent 1 Vent 2 Product outHydrocarbon in Steam in Catalyst in light Warning Computer controller Tank


    SciTech Connect (OSTI)

    K. Osseo-Asare; X. Zeng


    Ever-stringent environmental constraints dictate that future coal cleaning technologies be compatible with micron-size particles. This research program seeks to develop an advanced coal cleaning technology uniquely suited to micron-size particles, i.e., aqueous biphase extraction. The partitioning behaviors of silica in the polyethylene glycol (PEG)/dextran (Dex) and dextran/Triton X-100 (TX100) systems have been investigated, and the effects of sodium dodecylsulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) on solid partition have been studied. In both biphase systems, silica particles stayed in the top PEG-rich phase at low pH. With increase in pH, the particles moved from the top phase to the interface, then to the bottom phase. At very high pH, the solids preferred the top phase again. These trends are attributable to variations in the polymer/solid and nonionic surfactant/solid interactions. Addition of ionic surfactants into these two systems introduces a weakly charged environment, since ionic surfactants concentrate into one phase, either the top phase or the bottom phase. Therefore, coulombic forces also play a key role in the partition of silica particles because electrostatic attractive or repulsive forces are produced between the solid surface and the ionic-surfactant-concentrated phase. For the PEG/dextran system in the presence of SDS, SiO{sub 2} preferred the bottom dextran-rich phase above its pH{sub PZC}. However, addition of DTAB moved the oxide particles from the top phase to the interface, and then to the bottom phase, with increase in pH. These different behaviors are attributable to the fact that SDS and DTAB concentrated into the opposite phase of the PEG/dextran system. On the other hand, in the dextran/Triton X-100 system, both ionic surfactants concentrated in the top surfactant-rich phase and formed mixed micelles with TX100. Therefore, addition of the anionic surfactant, SDS, moved the silica particles from top phase to the interface or bottom phase. On the other hand, DTAB, a cationic surfactant, attracted the particles to the top phase in the pH range form 4 to 11, where in the DTAB-free system the solids either stayed at the interface or in the bottom phase.

  16. Uncovering Additional Clues to Galaxy Evolution. II. The Environmental Impact of the Virgo Cluster on the Evolution of Dwarf Irregular Galaxies

    E-Print Network [OSTI]

    Henry Lee; Marshall L. McCall; Michael G. Richer


    The impact of the cluster environment on the evolution of dwarf galaxies is investigated by comparing the properties of a sample of dwarf irregulars (dIs) in the Virgo Cluster with a control sample of nearby ("field") dIs having oxygen abundances derived from [O III]4363 measurements and measured distances from resolved stellar constituents. Spectroscopic data are obtained for H II regions in 11 Virgo dIs distributed in the central and outer regions of the cluster. To ensure that oxygen abundances are derived in a homogeneous manner, oxygen abundances for field and Virgo dIs are computed using the bright-line method and compared with abundances directly obtained from [O III]4363, where available. They are found to agree to within about 0.2 dex with no systematic offset. At a given optical luminosity, there is no systematic difference in oxygen abundance between the sample of Virgo dIs and the sample of nearby dIs. However, five of the eleven Virgo dIs exhibit much lower baryonic gas fractions than field dIs at comparable oxygen abundances. Using field dIs as a reference, a gas-deficiency index for dIs is constructed, making it possible quantitatively to identify which galaxies have lost gas. For the Virgo sample, some of the dwarfs are gas-deficient by a factor of 30. The gas-deficiency correlates roughly with the X-ray surface brightness of the intracluster gas. Ram-pressure stripping can best explain the observed gas-poor dIs in the cluster sample. Together with the lack of significant fading and reddening of the gas-poor dIs compared to gas-normal dIs, these observations suggest that the gas-poor dIs in Virgo have recently encountered the intracluster medium for the first time. Faded remnants of gas-poor dIs in Virgo will resemble bright dwarf ellipticals presently seen in the cluster core.


    SciTech Connect (OSTI)

    Ribas, I.; Garces, A. [Institut de Ciencies de l'Espai (CSIC-IEEC), Campus UAB, Facultat de Ciencies, Torre C5, parell, 2a pl., E-08193 Bellaterra (Spain); Porto de Mello, G. F.; Ferreira, L. D. [Universidade Federal do Rio de Janeiro, Observatorio do Valongo, Ladeira do Pedro Antonio 43, CEP: 20080-090, Rio de Janeiro, RJ (Brazil); Hebrard, E.; Selsis, F. [Universite de Bordeaux, Observatoire Aquitain des Sciences de l'Univers, 2 rue de l'Observatoire, BP 89, F-33271 Floirac Cedex (France); Catalan, S. [Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Do Nascimento, J. D.; De Medeiros, J. R., E-mail: iribas@ice.csic.e, E-mail: garces@ice.csic.e, E-mail: gustavo@astro.ufrj.b, E-mail: leticia@astro.ufrj.b, E-mail: franck.selsis@obs.u-bordeaux1.f, E-mail: eric.hebrard@obs.u-bordeaux1.f, E-mail:, E-mail: dias@dfte.ufrn.b, E-mail: renan@dfte.ufrn.b [Departamento de Fisica, Universidade Federal do Rio Grande do Norte, CEP: 59072-970, Natal, RN (Brazil)


    The early evolution of Earth's atmosphere and the origin of life took place at a time when physical conditions at the Earth were radically different from its present state. The radiative input from the Sun was much enhanced in the high-energy spectral domain, and in order to model early planetary atmospheres in detail, a knowledge of the solar radiative input is needed. We present an investigation of the atmospheric parameters, state of evolution, and high-energy fluxes of the nearby star {kappa}{sup 1} Cet, previously thought to have properties resembling those of the early Sun. Atmospheric parameters were derived from the excitation/ionization equilibrium of Fe I and Fe II, profile fitting of H{alpha}, and the spectral energy distribution. The UV irradiance was derived from Far-Ultraviolet Spectroscopic Explorer and Hubble Space Telescope data, and the absolute chromospheric flux from the H{alpha} line core. From careful spectral analysis and the comparison of different methods, we propose for {kappa}{sup 1} Cet the following atmospheric parameters: T{sub eff} = 5665 {+-} 30 K (H{alpha} profile and energy distribution), log g = 4.49 {+-} 0.05 dex (evolutionary and spectroscopic), and [Fe/H] = +0.10 {+-} 0.05 (Fe II lines). The UV radiative properties of {kappa}{sup 1} Cet indicate that its flux is some 35% lower than the current Sun's between 210 and 300 nm, it matches the Sun's at 170 nm, and increases to at least 2-7 times higher than the Sun's between 110 and 140 nm. The use of several indicators ascribes an age to {kappa}{sup 1} Cet in the interval {approx}0.4-0.8 Gyr and the analysis of the theoretical Hertzsprung-Russell diagram (H-R) suggests a mass {approx}1.04 M{sub sun}. This star is thus a very close analog of the Sun when life arose on Earth and Mars is thought to have lost its surface bodies of liquid water. Photochemical models indicate that the enhanced UV emission leads to a significant increase in photodissociation rates compared with those commonly assumed of the early Earth. Our results show that reliable calculations of the chemical composition of early planetary atmospheres need to account for the stronger solar photodissociating UV irradiation.


    SciTech Connect (OSTI)

    Stoll, R.; Stanek, K. Z.; Pogge, R. W. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210-1173 (United States); Prieto, J. L. [Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Peyton Hall, Princeton, NJ 08544 (United States)


    Type II supernovae (SNe) can be used as a star formation tracer to probe the metallicity distribution of global low-redshift star formation. We present oxygen and iron abundance distributions of Type II SN progenitor regions that avoid many previous sources of bias. Because iron abundance, rather than oxygen abundance, is of key importance for the late stage evolution of the massive stars that are the progenitors of core-collapse supernovae, and because iron enrichment lags oxygen enrichment, we find a general conversion from oxygen abundance to iron abundance. The distributions we present here are the best yet observational standard of comparison for evaluating how different classes of supernovae depend on progenitor metallicity. We spectroscopically measure the gas-phase oxygen abundance near a representative subsample of the hosts of Type II SNe from the first-year Palomar Transient Factory (PTF) SN search, using a combination of Sloan Digital Sky Survey (SDSS) spectra near the SN location (9 hosts) and new longslit spectroscopy (25 hosts). The median metallicity of these 34 hosts at or near the SN location is 12+log(O/H) = 8.65, with a median error of 0.09. The median host galaxy stellar mass from fits to SDSS photometry is 10{sup 9.9} M{sub Sun }. They do not show a systematic offset in metallicity or mass from a redshift-matched sample of the MPA/JHU value-added catalog. In contrast to previous SN host metallicity studies, this sample is drawn from a single survey. It is also drawn from an areal rather than a targeted survey, so SNe in the lowest-mass galaxies are not systematically excluded. Indeed, the PTF SN search has a slight bias toward following up transients in low mass galaxies. The progenitor region metallicity distribution we find is statistically indistinguishable from the metallicity distribution of Type II SN hosts found by targeted surveys and by samples from multiple surveys with different selection functions. Using the relationship between iron and oxygen abundances found for Milky Way disk, bulge, and halo stars, we translate our distribution of Type II SN environments as a function of oxygen abundance into an estimate of the iron abundance, since iron varies more steeply than oxygen. We find that though this sample spans only 0.65 dex in oxygen abundance, the gap between the iron and oxygen abundance is 50% wider at the low-metallicity end of our sample than at the high-metallicity end.


    SciTech Connect (OSTI)

    Weisz, Daniel R.; Fouesneau, Morgan; Dalcanton, Julianne J.; Clifton Johnson, L.; Beerman, Lori C.; Williams, Benjamin F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States)] [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Hogg, David W.; Foreman-Mackey, Daniel T. [Center for Cosmology and Particle Physics, New York University, 4 Washington Place, New York, NY 10003 (United States)] [Center for Cosmology and Particle Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Rix, Hans-Walter; Gouliermis, Dimitrios [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany)] [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Dolphin, Andrew E. [Raytheon Company, 1151 East Hermans Road, Tucson, AZ 85756 (United States)] [Raytheon Company, 1151 East Hermans Road, Tucson, AZ 85756 (United States); Lang, Dustin [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)] [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Bell, Eric F. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)] [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Gordon, Karl D.; Kalirai, Jason S. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)] [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Skillman, Evan D., E-mail: [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States)


    We present a probabilistic approach for inferring the parameters of the present-day power-law stellar mass function (MF) of a resolved young star cluster. This technique (1) fully exploits the information content of a given data set; (2) can account for observational uncertainties in a straightforward way; (3) assigns meaningful uncertainties to the inferred parameters; (4) avoids the pitfalls associated with binning data; and (5) can be applied to virtually any resolved young cluster, laying the groundwork for a systematic study of the high-mass stellar MF (M {approx}> 1 M {sub Sun }). Using simulated clusters and Markov Chain Monte Carlo sampling of the probability distribution functions, we show that estimates of the MF slope, {alpha}, are unbiased and that the uncertainty, {Delta}{alpha}, depends primarily on the number of observed stars and on the range of stellar masses they span, assuming that the uncertainties on individual masses and the completeness are both well characterized. Using idealized mock data, we compute the theoretical precision, i.e., lower limits, on {alpha}, and provide an analytic approximation for {Delta}{alpha} as a function of the observed number of stars and mass range. Comparison with literature studies shows that {approx}3/4 of quoted uncertainties are smaller than the theoretical lower limit. By correcting these uncertainties to the theoretical lower limits, we find that the literature studies yield ({alpha}) = 2.46, with a 1{sigma} dispersion of 0.35 dex. We verify that it is impossible for a power-law MF to obtain meaningful constraints on the upper mass limit of the initial mass function, beyond the lower bound of the most massive star actually observed. We show that avoiding substantial biases in the MF slope requires (1) including the MF as a prior when deriving individual stellar mass estimates, (2) modeling the uncertainties in the individual stellar masses, and (3) fully characterizing and then explicitly modeling the completeness for stars of a given mass. The precision on MF slope recovery in this paper are lower limits, as we do not explicitly consider all possible sources of uncertainty, including dynamical effects (e.g., mass segregation), unresolved binaries, and non-coeval populations. We briefly discuss how each of these effects can be incorporated into extensions of the present framework. Finally, we emphasize that the technique and lessons learned are applicable to more general problems involving power-law fitting.

  20. In Colombia

    E-Print Network [OSTI]


    28 LATIN AMERICAN THEATRE REVIEW In Colombia Muestras Regionales de Teatro. 95 groups presented plays in Bogot, Cali, Barranquilla, Bucaramanga and Medellin between September 1 and 7, 1975. Festival Nacional del Nuevo Teatro. October 6-17, 1975...

  1. In reply

    E-Print Network [OSTI]


    Wikis have been de?ned as Web sites that can be openlywere simply too many great Web sites to list them all in our

  2. High Dispersion Spectroscopy of Solar-type Superflare Stars. I. Temperature, Surface Gravity, Metallicity, and $v \\sin i$

    E-Print Network [OSTI]

    Notsu, Yuta; Maehara, Hiroyuki; Notsu, Shota; Shibayama, Takuya; Nogami, Daisaku; Shibata, Kazunari


    We conducted high dispersion spectroscopic observations of 50 superflare stars with Subaru/HDS, and measured the stellar parameters of them. These 50 targets were selected from the solar-type (G-type main sequence) superflare stars that we had discovered from the Kepler photometric data. As a result of these spectroscopic observations, we found that more than half (34 stars) of our 50 targets have no evidence of binary system. We then estimated effective temperature ($T_{\\rm{eff}}$), surface gravity ($\\log g$), metallicity ([Fe/H]), and projected rotational velocity ($v\\sin i$) of these 34 superflare stars on the basis of our spectroscopic data. The accuracy of our estimations is higher than that of Kepler Input Catalog (KIC) values, and the differences between our values and KIC values ($(\\Delta T_{\\rm{eff}})_{\\rm{rms}} \\sim 219$K, $(\\Delta \\log g)_{\\rm{rms}} \\sim 0.37$ dex, and $(\\Delta\\rm{[Fe/H]})_{\\rm{rms}} \\sim 0.46$ dex) are comparable to the large uncertainties and systematic differences of KIC values ...

  3. In vivo dosimetry in brachytherapy

    SciTech Connect (OSTI)

    Tanderup, Kari [Department of Oncology, Aarhus University Hospital, Aarhus 8000 (Denmark); Department of Clinical Medicine, Aarhus University, Aarhus 8000 (Denmark); Beddar, Sam [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Andersen, Claus E.; Kertzscher, Gustavo [Center of Nuclear Technologies, Technical University of Denmark, Roskilde 4000 (Denmark); Cygler, Joanna E. [Department of Physics, Ottawa Hospital Cancer Centre, Ottawa, Ontario K1H 8L6 (Canada)


    In vivo dosimetry (IVD) has been used in brachytherapy (BT) for decades with a number of different detectors and measurement technologies. However, IVD in BT has been subject to certain difficulties and complexities, in particular due to challenges of the high-gradient BT dose distribution and the large range of dose and dose rate. Due to these challenges, the sensitivity and specificity toward error detection has been limited, and IVD has mainly been restricted to detection of gross errors. Given these factors, routine use of IVD is currently limited in many departments. Although the impact of potential errors may be detrimental since treatments are typically administered in large fractions and with high-gradient-dose-distributions, BT is usually delivered without independent verification of the treatment delivery. This Vision 20/20 paper encourages improvements within BT safety by developments of IVD into an effective method of independent treatment verification.

  4. In Focus

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItemResearch > The Energy Materials Center at Cornell Research Highlights InIn

  5. In Memoriam

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC) EnvironmentalGyroSolé(tm)HydrogenRFP » Important TrinityEnergy the WaybyInIn

  6. In progress

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn Other News Community Connections: Your linkIn

  7. In progress

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn Other News Community Connections: Your linkInNo data


    SciTech Connect (OSTI)

    Andrews, Sean M.; Rosenfeld, Katherine A.; Kraus, Adam L.; Wilner, David J., E-mail: [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)


    We present a substantial extension of the millimeter (mm) wave continuum photometry catalog for circumstellar dust disks in the Taurus star-forming region, based on a new ''snapshot'' {lambda} = 1.3 mm survey with the Submillimeter Array. Combining these new data with measurements in the literature, we construct a mm-wave luminosity distribution, f(L{sub mm}), for Class II disks that is statistically complete for stellar hosts with spectral types earlier than M8.5 and has a 3{sigma} depth of roughly 3 mJy. The resulting census eliminates a longstanding selection bias against disks with late-type hosts, and thereby demonstrates that there is a strong correlation between L{sub mm} and the host spectral type. By translating the locations of individual stars in the Hertzsprung-Russell diagram into masses and ages, and adopting a simple conversion between L{sub mm} and the disk mass, M{sub d} , we confirm that this correlation corresponds to a statistically robust relationship between the masses of dust disks and the stars that host them. A Bayesian regression technique is used to characterize these relationships in the presence of measurement errors, data censoring, and significant intrinsic scatter: the best-fit results indicate a typical 1.3 mm flux density of {approx}25 mJy for 1 M{sub Sun} hosts and a power-law scaling L{sub mm}{proportional_to}M{sub *}{sup 1.5-2.0}. We suggest that a reasonable treatment of dust temperature in the conversion from L{sub mm} to M{sub d} favors an inherently linear M{sub d} {proportional_to}M{sub *} scaling, with a typical disk-to-star mass ratio of {approx}0.2%-0.6%. The measured rms dispersion around this regression curve is {+-}0.7 dex, suggesting that the combined effects of diverse evolutionary states, dust opacities, and temperatures in these disks imprint a full width at half-maximum range of a factor of {approx}40 on the inferred M{sub d} (or L{sub mm}) at any given host mass. We argue that this relationship between M{sub d} and M{sub *} likely represents the origin of the inferred correlation between giant planet frequency and host star mass in the exoplanet population, and provides some basic support for the core accretion model for planet formation. Moreover, we caution that the effects of incompleteness and selection bias must be considered in comparative studies of disk evolution, and illustrate that fact with statistical comparisons of f(L{sub mm}) between the Taurus catalog presented here and incomplete subsamples in the Ophiuchus, IC 348, and Upper Sco young clusters.

  9. Environmental Radioactivity in Greenland in 1981

    E-Print Network [OSTI]

    Ris-R-471 v Environmental Radioactivity in Greenland in 1981 A. Aarkrog, Henning Dahlgaard, Elis July 1962 #12;Ris-R-471 ENVIRONMENTAL RADIOACTIVITY IN GREENLAND IN 1981 A. Aarkrog, Henning Dahlgaard. Measurements of fallout radioactivity in Greenland in 1981 are reported. Strontium-90 (and Cesium-137 in most

  10. Environmental Radioactivity in Greenland in 1978

    E-Print Network [OSTI]

    ft I la 0 0 0 0 Risn-R-405 Environmental Radioactivity in Greenland in 1978 A. Aarkrog, Heinz ENVIRONMENTAL RADIOACTIVITY IN GREENLAND IN 1978 A. Aarkrog, Heinz Hansen and J. Lippert Abstract. Heasureaents of fallout radioactivity in Greenland in 1978 are reported. Strontium-90 (and Cesium-137 in most cases


    SciTech Connect (OSTI)

    Boyajian, Tabetha S.; McAlister, Harold A.; Jones, Jeremy; White, Russel; Henry, Todd; Gies, Douglas; Jao, Wei-Chun; Parks, J. Robert [Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, P.O. Box 4106, Atlanta, GA 30302-4106 (United States); Von Braun, Kaspar; Kane, Stephen R.; Ciardi, David [NASA Exoplanet Science Institute, California Institute of Technology, MC 100-22, Pasadena, CA 91125 (United States); Van Belle, Gerard [Lowell Observatory, Flagstaff, AZ 86001 (United States); Ten Brummelaar, Theo A.; Schaefer, Gail; Sturmann, Laszlo; Sturmann, Judit [The CHARA Array, Mount Wilson Observatory, Mount Wilson, CA 91023 (United States); Muirhead, Philip S. [Department of Astronomy, California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Lopez-Morales, Mercedes [Institut de Ciencies de L'Espai (CSIC-IEEC), E-08193 Bellaterra (Spain); Ridgway, Stephen [National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726-6732 (United States); Rojas-Ayala, Barbara [Department of Astrophysics, Division of Physical Sciences, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); and others


    We present interferometric angular diameter measurements of 21 low-mass, K- and M-dwarfs made with the CHARA Array. This sample is enhanced by adding a collection of radius measurements published in the literature to form a total data set of 33 K-M-dwarfs with diameters measured to better than 5%. We use these data in combination with the Hipparcos parallax and new measurements of the star's bolometric flux to compute absolute luminosities, linear radii, and effective temperatures for the stars. We develop empirical relations for {approx}K0 to M4 main-sequence stars that link the stellar temperature, radius, and luminosity to the observed (B - V), (V - R), (V - I), (V - J), (V - H), and (V - K) broadband color index and stellar metallicity [Fe/H]. These relations are valid for metallicities ranging from [Fe/H] = -0.5 to +0.1 dex and are accurate to {approx}2%, {approx}5%, and {approx}4% for temperature, radius, and luminosity, respectively. Our results show that it is necessary to use metallicity-dependent transformations in order to properly convert colors into stellar temperatures, radii, and luminosities. Alternatively, we find no sensitivity to metallicity on relations we construct to the global properties of a star omitting color information, e.g., temperature-radius and temperature-luminosity. Thus, we are able to empirically quantify to what order the star's observed color index is impacted by the stellar iron abundance. In addition to the empirical relations, we also provide a representative look-up table via stellar spectral classifications using this collection of data. Robust examinations of single star temperatures and radii compared to evolutionary model predictions on the luminosity-temperature and luminosity-radius planes reveal that models overestimate the temperatures of stars with surface temperatures <5000 K by {approx}3%, and underestimate the radii of stars with radii <0.7 R{sub Sun} by {approx}5%. These conclusions additionally suggest that the models over account for the effects that the stellar metallicity may have on the astrophysical properties of an object. By comparing the interferometrically measured radii for the single star population to those of eclipsing binaries, we find that for a given mass, single and binary star radii are indistinguishable. However, we also find that for a given radius, the literature temperatures for binary stars are systematically lower compared to our interferometrically derived temperatures of single stars by {approx}200 to 300 K. The nature of this offset is dependent on the validation of binary star temperatures, where bringing all measurements to a uniform and correctly calibrated temperature scale is needed to identify any influence stellar activity may have on the physical properties of a star. Lastly, we present an empirically determined H-R diagram using fundamental properties presented here in combination with those in Boyajian et al. for a total of 74 nearby, main-sequence, A- to M-type stars, and define regions of habitability for the potential existence of sub-stellar mass companions in each system.

  12. Study in Germany / Work in Germany

    E-Print Network [OSTI]

    Peak, Derek

    Study in Germany / Work in Germany Opportunities Prof. Dr. Silke R. Falkner German Programme Coordinator Tel.: 966-5744 #12;Content I. Opportunities for Study in Germany II. German in Germany V. Term II courses #12;I.A. Study in Germany (Summer) 1. CSSG: Canadian Summer School in Germany

  13. Iran in History Iran in History

    E-Print Network [OSTI]

    Mohaghegh, Shahab

    1 Iran in History Iran in History by Bernard Lewis In attempting to attain some perspective on Iran. These events have been variously seen in Iran: by some as a blessing, the advent of the true faith, the end remarkable difference between what happened in Iran and what happened in all the other countries


    SciTech Connect (OSTI)

    Kulkarni, Girish; Hennawi, Joseph F. [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Rollinde, Emmanuel; Vangioni, Elisabeth, E-mail: [Institut d'Astrophysique de Paris, UMR 7095, UPMC, Paris VI, 98 bis boulevard Arago, F-75014 Paris (France)


    Observations of damped Ly{alpha} absorbers (DLAs) can be used to measure gas-phase metallicities at large cosmological look-back times with high precision. Furthermore, relative abundances can still be measured accurately deep into the reionization epoch (z > 6) using transitions redward of Ly{alpha}, even though Gunn-Peterson absorption precludes measurement of neutral hydrogen. In this paper, we study the chemical evolution of DLAs using a model for the coupled evolution of galaxies and the intergalactic medium (IGM), which is constrained by a variety of observations. Our goal is to explore the influence of Population III stars on the abundance patterns of DLAs to determine the degree to which abundance measurements can discriminate between different Population III stellar initial mass functions (IMFs). We include effects, such as inflows onto galaxies due to cosmological accretion and outflows from galaxies due to supernova feedback. A distinct feature of our model is that it self-consistently calculates the effect of Population III star formation on the reionization of an inhomogeneous IGM, thus allowing us to calculate the thermal evolution of the IGM and implement photoionization feedback on low-mass galaxy formation. We find that if the critical metallicity of Population III to II/I transition is {approx}< 10{sup -4} Z{sub Sun }, then the cosmic Population III star formation rate drops to zero for z < 8. Nevertheless, at high redshift (z {approx} 6), chemical signatures of Population III stars remain in low-mass galaxies (halo mass {approx}< 10{sup 9} M{sub Sun }). This is because photoionization feedback suppresses star formation in these galaxies until relatively low redshift (z {approx} 10), and the chemical record of their initial generation of Population III stars is retained. We model DLAs as these low-mass galaxies, and assign to them a mass-dependent H I absorption cross-section in order to predict the expected distribution of DLA abundance ratios. We find that these distributions are anchored toward abundance ratios set by Population II supernova yields, but they exhibit a tail which depends significantly on the Population III IMF for z > 5. Thus, a sample of DLA metallicity and relative abundance measurements at high redshift holds the promise to constrain Population III enrichment and the Population III IMF. We find that a sample of just 10 DLAs with relative abundances measured to an accuracy of 0.1 dex is sufficient to constrain the Population III IMF at 4{sigma}. These constraints may prove stronger than other probes of Population III enrichment, such as metal-poor stars and individual metal-poor DLAs. Our results provide a global picture of the thermal, ionization, and chemical evolution of the universe, and have the potential to rule out certain Population III scenarios.

  15. Recent Trends in Land Tenure in Texas.

    E-Print Network [OSTI]

    Motheral, Joe


    colored; in Harrison County, 70 per cent; in Gregg County, 60 per cent; in San Jacinto County, 57 per cent; and in Walker County, 51 per cent. Almost one-third of the farm operators in counties along the lower reaches of the Colorado and Brazos rivers...RECENT TRENDS IN LAND TENURE IN TEXAS JOE MOTHERAL Division of Farm and Ranch Economics [Blank Page in Original Bulletin] Public interest in the subject of land tenure has been height- ened by the swift changes, in the tenure pattern...

  16. Popular Theatre in Ethiopia

    E-Print Network [OSTI]

    Ashagrie, Aboneh


    bqinninl oflbeltte in Ethiopia] . (trans. from Amlwie), (such community theatre in Ethiopia with special reference tocommunity development in Ethiopia will be pro posed in th e

  17. In situ groundwater bioremediation

    E-Print Network [OSTI]

    Hazen, Terry C.


    field applicability. In: Bioremediation Field Experience, (Art. In: Applied Bioremediation of Petroleum Hydrocarbons. (C. D. 1993. In situ bioremediation: basis and practices. In:

  18. Essays in Applied Microeconomics

    E-Print Network [OSTI]

    Severnini, Edson Roberto


    mobilize to build aluminum smelters in the Northwest. ALCOAthe property for a smelter in Longview, Washington, in 1940.the Longview facility. The smelter opened in September 1941,


    SciTech Connect (OSTI)

    Rodriguez-Puebla, Aldo; Avila-Reese, Vladimir; Drory, Niv, E-mail: [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, A. P. 70-264, 04510 Mexico, DF (Mexico)


    Several occupational distributions for satellite galaxies more massive than m{sub *} Almost-Equal-To 4 Multiplication-Sign 10{sup 7} M{sub Sun} around Milky-Way (MW)-sized hosts are presented and used to predict the internal dynamics of these satellites as a function of m{sub *}. For the analysis, a large galaxy group mock catalog is constructed on the basis of (sub)halo-to-stellar mass relations fully constrained with currently available observations, namely the galaxy stellar mass function decomposed into centrals and satellites, and the two-point correlation functions at different masses. We find that 6.6% of MW-sized galaxies host two satellites in the mass range of the Small and Large Magellanic Clouds (SMC and LMC, respectively). The probabilities of the MW-sized galaxies having one satellite equal to or larger than the LMC, two satellites equal to or larger than the SMC, or three satellites equal to or larger than Sagittarius (Sgr) are Almost-Equal-To 0.26, 0.14, and 0.14, respectively. The cumulative satellite mass function of the MW, N{sub s} ({>=}m{sub *}) , down to the mass of the Fornax dwarf is within the 1{sigma} distribution of all the MW-sized galaxies. We find that MW-sized hosts with three satellites more massive than Sgr (as the MW) are among the most common cases. However, the most and second most massive satellites in these systems are smaller than the LMC and SMC by roughly 0.7 and 0.8 dex, respectively. We conclude that the distribution N{sub s} ({>=}m{sub *}) for MW-sized galaxies is quite broad, the particular case of the MW being of low frequency but not an outlier. The halo mass of MW-sized galaxies correlates only weakly with N{sub s} ({>=}m{sub *}). Then, it is not possible to accurately determine the MW halo mass by means of its N{sub s} ({>=}m{sub *}); from our catalog, we constrain a lower limit of 1.38 Multiplication-Sign 10{sup 12} M{sub Sun} at the 1{sigma} level. Our analysis strongly suggests that the abundance of massive subhalos should agree with the abundance of massive satellites in all MW-sized hosts, i.e., there is not a missing (massive) satellite problem for the {Lambda}CDM cosmology. However, we confirm that the maximum circular velocity, v{sub max}, of the subhalos of satellites smaller than m{sub *} {approx} 10{sup 8} M{sub Sun} is systematically larger than the v{sub max} inferred from current observational studies of the MW bright dwarf satellites; different from previous works, this conclusion is based on an analysis of the overall population of MW-sized galaxies. Some pieces of evidence suggest that the issue could refer only to satellite dwarfs but not to central dwarfs, then environmental processes associated with dwarfs inside host halos combined with supernova-driven core expansion should be on the basis of the lowering of v{sub max}.

  20. Federal Participation in LEED in 2005

    SciTech Connect (OSTI)

    Payne, Christopher; Dyer, Beverly


    The federal government is an active participant in promotingsustainable design, construction and operations and in the use of USGBC'sLeadership in Energy and Environmental Design (LEED) Green BuildingRating System. This paper presents an overview of sustainableconstruction activities in the federal sector in 2005.

  1. Individual variation in cooperative behaviour in meerkats

    E-Print Network [OSTI]

    English, Sinad


    Individual variation in cooperation is a striking yet poorly understood feature of many animal societies, particularly in cooperative breeders where individuals assist in the care of young that are not their own. While previous research...

  2. Geothermal Prospects in Colorado

    Broader source: [DOE]

    Geothermal Prospects in Colorado presentation at the April 2013 peer review meeting held in Denver, Colorado.

  3. State Experience in Hydrogen Infrastructure in California

    Broader source: (indexed) [DOE]

    Experience in Hydrogen Infrastructure in California Gerhard H Achtelik Jr. February 17, 2011 Hydrogen Infrastructure Market Readiness Workshop California Environmental Protection...

  4. Petroleum developments in North Africa in 1979

    SciTech Connect (OSTI)

    Nicod, M.A.


    In the 6 countries covered by this report, the extent of valid petroleum rights, seismic work, and drilling was nearly the same as in 1978. The success rate of wildcat drilling decreased slightly, to 28% (33% in 1978), with 26 oil or gas discoveries. In southwestern Tunisia, the Amoco Sabrina Nord 1 tested 930 bbl of 39/sup 0/ APl oil from Cambrian-Ordovician sandstones - the first oil to come from lower Paleozoic rocks in Tunisia. First commercial oil from Cambrian-Ordovician rocks in western Libya was discovered by Agip A1-NC40 which flowed 1,400 b/d. Highlight of the year in North Africa was in the interior basin of Sudan where the Chevron Abu Gabra 1 tested 900 BOPD of 40/sup 0/ APl oil from Cretaceous rocks; 2 other wells, spudded in late 1979 in the same area, have tested 3,200 and 7,300 b/d, respectively, in early 1980. Discovery well of the interior basin was Chevron Unity 1 which tested small amounts of oil in 1978. Oil production in North Africa in 1979 averaged 3,939,500 b/d compared with 3,802,800 b/d in 1978, an increase of 3.6%.

  5. Acid Violence in Pakistan

    E-Print Network [OSTI]

    Zia, Taiba


    womens rights advocate in Pakistan believe that a woman canViolence Legislation in Pakistan, Huffington Post, Octoberagainst Women in Pakistan. Karachi: Oxford University Press,

  6. Essays in Team Economics

    E-Print Network [OSTI]

    Tumlinson, Justin


    in Adverse Selection in Team Formation under DiscriminationAdverse Selection in Team Formation under Discrimination [J. A. , and Owan, H. , Team Incentives and Worker

  7. Essays in behavioral economics

    E-Print Network [OSTI]

    Eil, David Holding


    Essays in Behavioral Economics A dissertation submitted inDoctor of Philosophy in Economics by David Holding Eilfunction, The Review of Economics and Statistics, 1995,

  8. Essays in Economics

    E-Print Network [OSTI]

    Romem, Israel Hadas


    Kingdom in Ancient Egypt Introduction . . . . . . . . . .D. and E. Teeter (2007). Egypt and the Egyptians. Cambridge:of the State in Ancient Egypt. Explorations in Economic

  9. In situ groundwater bioremediation

    E-Print Network [OSTI]

    Hazen, Terry C.


    degradation of phenols in groundwater. J Contam. Hydrol.Bioimmobilization of Cr(VI) in Groundwater Using Hydrogenof bacterial activity in groundwater containing petroleum

  10. In vivo dosimetry in external beam radiotherapy

    SciTech Connect (OSTI)

    Mijnheer, Ben [Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam 1066 CX (Netherlands); Beddar, Sam [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Izewska, Joanna [Division of Human Health, International Atomic Energy Agency, Vienna 1400 (Austria); Reft, Chester [Department of Radiation and Cellular Oncology, University of Chicago Medical Center, Chicago, Illinois 60637 (United States)


    In vivo dosimetry (IVD) is in use in external beam radiotherapy (EBRT) to detect major errors, to assess clinically relevant differences between planned and delivered dose, to record dose received by individual patients, and to fulfill legal requirements. After discussing briefly the main characteristics of the most commonly applied IVD systems, the clinical experience of IVD during EBRT will be summarized. Advancement of the traditional aspects of in vivo dosimetry as well as the development of currently available and newly emerging noninterventional technologies are required for large-scale implementation of IVD in EBRT. These new technologies include the development of electronic portal imaging devices for 2D and 3D patient dosimetry during advanced treatment techniques, such as IMRT and VMAT, and the use of IVD in proton and ion radiotherapy by measuring the decay of radiation-induced radionuclides. In the final analysis, we will show in this Vision 20/20 paper that in addition to regulatory compliance and reimbursement issues, the rationale for in vivo measurements is to provide an accurate and independent verification of the overall treatment procedure. It will enable the identification of potential errors in dose calculation, data transfer, dose delivery, patient setup, and changes in patient anatomy. It is the authors' opinion that all treatments with curative intent should be verified through in vivo dose measurements in combination with pretreatment checks.

  11. Essays in labor economics

    E-Print Network [OSTI]

    Williams, Tyler (Tyler Kenneth)


    I addressed three questions in Labor Economics, using experimental and quasi-experimental variation to determine causality. In the first chapter, I ask whether playing longer in the NFL increases mortality in retirement. ...

  12. in partnership Partnerships

    E-Print Network [OSTI]

    and difference: populations of African descent in Mexico and Central America", in Mexico. Study of the Humboldt, in Argentina. Conference on metal pollution and its impact on the environment, health and society, in Bolivia

  13. Feed-in Tariff

    Broader source: [DOE]

    In September 2009, the Hawaii Public Utilities Commission (PUC) issued a decision that established a feed-in tariff in Hawaii. The feed-in tariff is offered by the three investor-owned utilities:...

  14. "Clean solutions; in research and in education."

    E-Print Network [OSTI]

    Acton, Scott

    waves in fluid that are coupled to bending waves in the elastic cover. At low frequencies, the lateral GRANTS · ONR ­ Composite Solutions to the Thermal Buckling of Plates Subjected to Localized

  15. Trumpeting M Dwarfs with CONCH-SHELL: a Catalog of Nearby Cool Host-Stars for Habitable ExopLanets and Life

    E-Print Network [OSTI]

    Gaidos, E; Lepine, S; Buccino, A; James, D; Ansdell, M; Petrucci, R; Mauas, P; Hilton, E J


    We present an all-sky catalog of 2970 nearby ($d \\lesssim 50$ pc), bright ($JDoppler radial velocity surveys. Stars were selected from the SUPERBLINK proper motion catalog according to absolute magnitudes, spectra, or a combination of reduced proper motions and photometric colors. From our spectra we determined gravity-sensitive indices, and identified and removed 0.2% of these as interloping hotter or evolved stars. Thirteen percent of the stars exhibit H-alpha emission, an indication of stellar magnetic activity and possible youth. The mean metallicity is [Fe/H] = -0.07 with a standard deviation of 0.22 dex, similar to nearby solar-type stars. We determined stellar effective temperatures by least-squares fitting of spectra to model predictions calibrated by fits to sta...

  16. Developments in oil shale in 1987

    SciTech Connect (OSTI)

    Knutson, C.F.; Dana, G.F.; Solti, G.; Qian, J.L.; Ball, F.D.; Hutton, A.C.; Hanna, J.; Russell, P.L.; Piper, E.M.


    Oil shale development continued at a slow pace in 1987. The continuing interest in this commodity is demonstrated by the 342 oil shale citations added to the US Department of Energy Energy Database during 1987. The Unocal project in Parachute, Colorado, produced 600,000 bbl of synfuel in 1987. An appreciable amount of 1987's activity was associated with the nonsynfuel uses of oil shale. 4 figs., 2 tabs.

  17. Segregation of In to dislocations in InGaN

    E-Print Network [OSTI]

    Horton, Matthew K.; Rhode, Sneha; Sahonta, Suman-Lata; Kappers, Menno J.; Haigh, Sarah J.; Pennycook, Timothy J.; Humphreys, Colin J.; Dusane, Rajiv O.; Moram, Michelle A.


    .; Fischer, A. J.; Thaler, G.; Banas, M. A. Effect of dislocation density on efficiency droop in GaInN?GaN light-emitting diodes. Applied Physics Letters 2007, 91, 231114 DOI: 10.1063/1.2822442. (3) Schubert, M. F.; Xu, J.; Kim, J. K.; Schubert, E. F.; Kim... , M. H.; Yoon, S.; Lee, S. M.; Sone, C.; Sakong, T.; Park, Y. Polarization-matched GaInN?AlGaInN multi-quantum-well light-emitting diodes with reduced efficiency droop. Applied Physics Letters 2008, 93, 041102 DOI: 10.1063/1.2963029. (4) Hsu, J. W. P...


    E-Print Network [OSTI]

    Subramaniam, Anandh

    Diffusion bonding To comprehend many materials related phenomenon one must understand Diffusion. The focusDIFFUSION IN SOLIDSDIFFUSION IN SOLIDS FICK'S LAWS KIRKENDALL EFFECT ATOMIC MECHANISMS Diffusion in Solids P.G. Shewmon McGraw-Hill, New York (1963) #12;Oxidation Roles of Diffusion Creep Aging

  19. Tubulin in vitro, in vivo and in silico

    E-Print Network [OSTI]

    Mershin, Andreas


    ACCUMULATION IN DROSOPHILA MUSHROOM BODY NEURONS RESULTS IN NEUROPLASTICITY IMPAIRMENT ............. 43 3.1 Introduction.............................................................................................. 43 3.2 Drosophila................................................................................... 6 2 Schematic of Quantum Teleportation of Dipole States.................................. 39 3 An XOR (exclusive-OR) Logic Gate............................................................. 40 4 Fly Mushroom Bodies (MBs...

  20. Oats in Texas.

    E-Print Network [OSTI]

    Spears, Ben; Coffey, Lee


    of a plant and \\ restricts the yield. Late grazing usually re- duces yield. In general, oats should not be I grazed after February 20 in Area 4 (figure 1.) ; February 28 in Area 3; March 5 in Area 2 and ' \\Inrrh 10 in Area 1. Early...

  1. New Developments in GIS in Water Resources

    E-Print Network [OSTI]

    Maidment, David


    Standardized formats Data: Dynamic in time Simple in space (points) No standardized formats What is Hydro? Hydrology Hydrography Circulation of the waters of the earth through the hydrologic cycle The blue lines on maps Properties of Water... of query functions Returns data in WaterML Services-Oriented Architecture for Water Data Links geographically distributed information servers through internet Web Services Description Language (WSDL from W3C) We designed WaterML as a web...


    E-Print Network [OSTI]


    on a fixed time horizon T = [0,tf] with differential states y : T ?? Rny , fixed model ...... mal experimental design of a catalytic fixed bed reactor, in Proceedings of...

  3. Homeless in America, Homeless in California

    E-Print Network [OSTI]

    Quigley, John M.; Raphael, Steven; Smolensky, Eugene


    418438. Mansur, Erin, John M. Quigley, Steven Raphael, andHOMELESS IN CALIFORNIA John M. Quigley, Steven Raphael, and

  4. UF in Osnabrck Understanding Engineering in Europe

    E-Print Network [OSTI]

    Jawitz, James W.

    the chance to climb a 100 meter tall wind generator tower! About the Location Osnabrück is located in Lower

  5. Inspection Methods in Programming

    E-Print Network [OSTI]

    Rich, Charles


    The work reported here lies in the area of overlap between artificial intelligence software engineering. As research in artificial intelligence, it is a step towards a model of problem solving in the domain of ...

  6. Dynamics in Formal Argumentation

    E-Print Network [OSTI]

    Carbogim, Daniela Vasconcelos

    by constructing and weighing up arguements intended to give support in favour or against alternative conclusions. In dynamic argumentation, such arguements may be revised and strengthened in order yo increase to decrease the acceptability of controversial...

  7. Corruption in Developing Countries

    E-Print Network [OSTI]

    Olken, Benjamin A.

    Recent years have seen a remarkable expansion in economists' ability to measure corruption. This in turn has led to a new generation of well-identified, microeconomic studies. We review the evidence on corruption in ...

  8. Exceptional Situations in Lisp

    E-Print Network [OSTI]

    Pitman, Kent M.

    Frequently, it is convenient to describe a program in terms of the normal situations in which it will be used, even if such a description does not describe the its complete behavior in all circumstances. This paper surveys ...

  9. Shakespeare Studies in China

    E-Print Network [OSTI]

    Meng, Hui


    , the characteristic of Shakespeare studies in China is closely associated with the political and cultural situation of the time. This thesis chronicles and analyzes noteworthy scholarship of Shakespeare studies in China, especially since the 1990s, in terms...

  10. Bacteria in shear flow

    E-Print Network [OSTI]

    Marcos, Ph.D. Massachusetts Institute of Technology


    Bacteria are ubiquitous and play a critical role in many contexts. Their environment is nearly always dynamic due to the prevalence of fluid flow: creeping flow in soil, highly sheared flow in bodily conduits, and turbulent ...

  11. Foreign Deities in Egypt

    E-Print Network [OSTI]

    Zivie-Coche, Christiane


    fig. 211. ) Foreign Deities in Egypt, Zivie-Coche, UEE 2011god Hauron and his cult in Egypt. Gttinger Miszellen 107,2011, Foreign Deities in Egypt. UEE. Full Citation: Zivie-

  12. Fraud Detection in Healthcare

    SciTech Connect (OSTI)

    Chandola, Varun [ORNL; Schryver, Jack C [ORNL; Sukumar, Sreenivas R [ORNL


    We discuss the problem of fraud detection in healthcare in this chapter. Given the recent scrutiny of the ineciencies in the US healthcare system, identifying fraud has been on the forefront of the eorts towards reducing the healthcare costs. In this chapter we will focus on understanding the issue of healthcare fraud in detail, and review methods that have been proposed in the literature to combat this issue using data driven approach.

  13. Early enlightenment in Istanbul

    E-Print Network [OSTI]

    Kck, Bekir Harun


    Thessaloniki : Institute for Balkan Studies, 1974 Cantemir,and National Identity in Ottoman Balkan Society, 14531821,"and National Identity in Ottoman Balkan Society, 14531821,"

  14. Investing in Math Education

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

    Investing in Math Education 1663 Los Alamos science and technology magazine Latest Issue:January 2015 All Issues submit Investing in Math Education Making good on the Lab's...

  15. Top quark in theory

    E-Print Network [OSTI]

    Eric Laenen


    I review how the top quark is embedded in the Standard Model and some its proposed extensions, and how it manifests itself in various hadron collider signals.


    E-Print Network [OSTI]

    Calvin, Melvin


    QUANTUM CONVERSION IN PHOTOSYNTHESIS Melvin Calvin Januaryas it occurs in modern photosynthesis can only take place inof the problem or photosynthesis, or any specific aspect of

  17. Essays in Development Economics

    E-Print Network [OSTI]

    Bazzi, Samuel Ali

    are weak, Review of Economics and Statistics, 2004, 86,Essays in Development Economics A dissertation submitted indegree Doctor of Philosophy in Economics by Samuel Ali Bazzi

  18. Advances in NMR Methodology

    E-Print Network [OSTI]

    Trease, David Richard


    to masking tape, before casting in epoxy resin . . . . .material, such as epoxy resin, changing the concentration ofbefore casting in epoxy resin the magnetic permeability of

  19. article in press

    E-Print Network [OSTI]


    United States alone (Russo, 2004). In response, several measures ..... where dr and dc are the death rates of the rats and the birds respectively. In the following,.

  20. Interconnect Issues in NE

    Broader source: [DOE]

    Presentation covers interconnect issues in the Northeast and is given at the Spring 2010 Federal Utility Partnership Working Group (FUPWG) meeting in Providence, Rhode Island.

  1. Reversible phosphorylation in mitochondria

    E-Print Network [OSTI]

    Rardin, Matthew James


    protein OM Outer membrane PDC Pyruvate dehydrogenase complexdehydrogenase complex (PDC). Polyclonal antibodies wereantibodies can detect changes in PDC activity in response to

  2. Demand Response In California

    Broader source: [DOE]

    Presentation covers the demand response in California and is given at the FUPWG 2006 Fall meeting, held on November 1-2, 2006 in San Francisco, California.


    SciTech Connect (OSTI)

    Kearns, Edward [Boston Universiy] [Boston Universiy


    This is the final report for the Department of Energy Grant to Principal Investigators in Experimental and Theoretical Particle Physics at Boston University. The research performed was in the Energy Frontier at the LHC, the Intensity Frontier at Super-Kamiokande and T2K, the Cosmic Frontier and detector R&D in dark matter detector development, and in particle theory.

  4. Graduate Certificate in Transportation

    E-Print Network [OSTI]

    Bertini, Robert L.

    Graduate Certificate in Transportation Nohad A. Toulan School of Urban Studies and Planning of Engineering and Computer Science integrated transportation systems. The Graduate Certificate in Transportation their capabilities. Students in the program can choose among a wide range of relevant courses in transportation

  5. IN TODAY'S PAPER International

    E-Print Network [OSTI]

    India's participation in the multi-billion-dollar International Thermonuclear Reactor project which aims

  6. Problems in Engineering and

    E-Print Network [OSTI]

    Eagar, Thomas W.

    Problems in Engineering and Science Education Why Do We Have a Weakness in Materials Synthesis, Materials Science and Engineering in the 1990s: Maintaining Competitiveness in the Age of Materials science and engi- neering alone; it is symptomatic of the way we teach all science and engineering. We

  7. Advances in iridium alloy processing in 1987

    SciTech Connect (OSTI)

    Heestand, R.L.; Ohriner, E.K.; Roche, T.K.


    A new process for the production of DOP-26 iridium alloy blanks is being evaluated and optimized. The alloy is prepared by electron-beam (EB) melting of Ir-0.3% W powder compacts followed by doping with aluminum and thorium by arc melting. Drop-cast alloy rod segments are EB welded to produce an electrode that is consumable arc melted to produce an ingot for extrusion and subsequent rolling. Initial results showed rejections for ultrasonic indications of alloy blanks produced by this process to be very low. Subsequently, some ingots have exhibited delaminations in the sheet, leading to rejection rates similar to that obtained in the standard process. The increase in delaminations is related to near-surface porosity in the consumable arc-melted ingot. A number of modifications to the arc-melting process and plans for further experimental work are described. In addition, the tensile properties of the DOP-26 iridium alloys have been measured over a range of test temperatures and strain rates. A laboratory evaluation of alternative cleaning procedures indicates that electrolytic dissolution of DOP-26 iridium alloy in an HCl solution is a potential substitute to the KCN process now in use. 7 refs., 13 figs., 6 tabs.

  8. Nuclear spirals in galaxies

    E-Print Network [OSTI]

    Witold Maciejewski


    Recent high-resolution observations indicate that nuclear spirals are often present in the innermost few hundred parsecs of disc galaxies. My models show that nuclear spirals form naturally as a gas response to non-axisymmetry in the gravitational potential. Some nuclear spirals take the form of spiral shocks, resulting in streaming motions in the gas, and in inflow comparable to the accretion rates needed to power local Active Galactic Nuclei. Recently streaming motions of amplitude expected from the models have been observed in nuclear spirals, confirming the role of nuclear spirals in feeding of the central massive black holes.

  9. In other news

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn Other News Community Connections: Your link toinaInInInInInIn

  10. Community work in vocational agriculture in Texas

    E-Print Network [OSTI]

    Vickery, Clarence Percell


    agriculture traiaing I Suspioioa oa the part oS ~ that there will be oharges iJ azy services are rcmdere4 3 That o14 problea? Ot staging in the sons 014 Rut Chat pa4 en4 Qxank pak " before hia fbllowe4 4 Skeptieisa as to the wins oC agrioulture training... that is simple and gives infomation tbat is of most uso to hia 2 (Sapor) (minor ) (Xone) Do you have difficultp in helping the farmer to solve his farm ~ment pxoblems 2 (Sapor) (Hinor) (Sons) Do you have diffioulty in assuring the best max)cote at the right...

  11. Causal networks in EIA

    SciTech Connect (OSTI)

    Perdicoulis, Anastassios [Departamento de Engenharia Biologica e Ambiental, Universidade de Tras-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila Real (Portugal)]. E-mail:; Glasson, John [Oxford Brookes University, Oxford Institute for Sustainable Development, School of the Built Environment, Headington Campus, Gipsy Lane, Oxford OX3 0BP (United Kingdom)]. E-mail:


    Causal networks have been used in Environmental Impact Assessment (EIA) since its early days, but they appear to have a minimal use in modern practice. This article reviews the typology of causal networks in EIA as well as in other academic and professional fields, verifies their contribution to EIA against the principles and requirements of the process, and discusses alternative scenarios for their future in EIA.

  12. Homotopy in statistical physics

    E-Print Network [OSTI]

    Ralph Kenna


    In condensed matter physics and related areas, topological defects play important roles in phase transitions and critical phenomena. Homotopy theory facilitates the classification of such topological defects. After a pedagogic introduction to the mathematical methods involved in topology and homotopy theory, the role of the latter in a number of mainly low-dimensional statistical-mechanical systems is outlined. Some recent activities in this area are reviewed and some possible future directions are discussed.

  13. Experiences in Applying Formal Verification in Robotics

    E-Print Network [OSTI]

    Lth, Christoph - Deutschen Forschungszentrum fr Knstliche Intelligenz & Fachbereich 3

    and certifying a safety function for autonomous vehicles and robots. We out- line the algorithm which such as the area covered by a braking robot in our case, play a central role. This leads to an increase

  14. Dust Measurements in Tokamaks

    SciTech Connect (OSTI)

    Rudakov, D; Yu, J; Boedo, J; Hollmann, E; Krasheninnikov, S; Moyer, R; Muller, S; Yu, A; Rosenberg, M; Smirnov, R; West, W; Boivin, R; Bray, B; Brooks, N; Hyatt, A; Wong, C; Fenstermacher, M; Groth, M; Lasnier, C; McLean, A; Stangeby, P; Ratynskaia, S; Roquemore, A; Skinner, C; Solomon, W M


    Dust production and accumulation impose safety and operational concerns for ITER. Diagnostics to monitor dust levels in the plasma as well as in-vessel dust inventory are currently being tested in a few tokamaks. Dust accumulation in ITER is likely to occur in hidden areas, e.g. between tiles and under divertor baffles. A novel electrostatic dust detector for monitoring dust in these regions has been developed and tested at PPPL. In DIII-D tokamak dust diagnostics include Mie scattering from Nd:YAG lasers, visible imaging, and spectroscopy. Laser scattering resolves size of particles between 0.16-1.6 {micro}m in diameter; the total dust content in the edge plasmas and trends in the dust production rates within this size range have been established. Individual dust particles are observed by visible imaging using fast-framing cameras, detecting dust particles of a few microns in diameter and larger. Dust velocities and trajectories can be determined in 2D with a single camera or 3D using multiple cameras, but determination of particle size is problematic. In order to calibrate diagnostics and benchmark dust dynamics modeling, pre-characterized carbon dust has been injected into the lower divertor of DIII-D. Injected dust is seen by cameras, and spectroscopic diagnostics observe an increase of carbon atomic, C2 dimer, and thermal continuum emissions from the injected dust. The latter observation can be used in the design of novel dust survey diagnostics.

  15. Nuclear Masses in Astrophysics

    E-Print Network [OSTI]

    Christine Weber; Klaus Blaum; Hendrik Schatz


    Among all nuclear ground-state properties, atomic masses are highly specific for each particular combination of N and Z and the data obtained apply to a variety of physics topics. One of the most crucial questions to be addressed in mass spectrometry of unstable radionuclides is the one of understanding the processes of element formation in the Universe. To this end, accurate atomic mass values of a large number of exotic nuclei participating in nucleosynthesis are among the key input data in large-scale reaction network calculations. In this paper, a review on the latest achievements in mass spectrometry for nuclear astrophysics is given.

  16. Iron efficiency in sorghum

    E-Print Network [OSTI]

    Esty, James Craig


    . DeKoch (28) indicated that the total amount of Fe in the roots of plants bears little relation to chlorosis, as roots of chlorotic plants may contain a higher percentage of Fe than roots of healthy plants. Fe was internally inactivated in soybeans...) developed a technique to de- termine Fe efficiency in plants, they stated that some control of pH was needed in the growth medium and they + accomplished this by using NO 3 nitrogen and NH 4 nitrogen in nutrient solutions. A decrease in pH of the growth...

  17. In other news

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn Other News Community Connections: Your link toinaInInInInIn

  18. Energy in density gradient

    E-Print Network [OSTI]

    Vranjes, J


    Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindric configuration. This is of practical importance for drift wave instability in various plasmas, and in particular in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit ...

  19. Computational in structural and

    E-Print Network [OSTI]

    Head-Gordon, Teresa L.

    genomes or biological pathways. It is, in fact, a logical extension of the genome effort to systematically to discoveries coming from genome projects on hu- man and model organisms. In the next century we can begin

  20. Specific light in sculpture

    E-Print Network [OSTI]

    Powell, John William


    Specific light is defined as light from artificial or altered natural sources. The use and manipulation of light in three dimensional sculptural work is discussed in an historic and contemporary context. The author's work ...

  1. Cutaneous leishmaniasis in Pakistan

    E-Print Network [OSTI]

    Khan, Shiraz Jamal; Muneeb, Syed


    from various regions of Pakistan. J Coll Physicians SurgR. Cutaneous Leishmaniasis in Pakistan. Int J Dermatol. 2001cutaneous leishmaniasis in Pakistan: a 6-year study. Int J

  2. Energy Refits in Philadelphia

    Broader source: [DOE]

    The Greater Philadelphia region's historic buildings and homes are among the most significant in American history, but they predate modern energy-efficient designs by centuries. In fact, some...

  3. Derivative actions in China

    E-Print Network [OSTI]

    Lin, Shaowei


    The enactment of derivative action was expected to be actively used by shareholders to protect their interests. In fact, it turned out that this reform effort seemed futile as the right to engage in such actions was ...

  4. Holes in Spectral Lines

    E-Print Network [OSTI]

    Fontana, Peter R.; Srivastava, Rajendra P.


    The decay of an atom in the presence of a static perturbation is investigated. The perturbation couples a decaying state with a nondecaying state. A "hole" appears in the emission line at a frequency equal to the frequency difference between...

  5. Essays in financial economics/

    E-Print Network [OSTI]

    Mullins, William, Ph. D. Massachusetts Institute of Technology


    This thesis examines three questions in Corporate Finance. The first chapter investigates the effect of institutional ownership on the governance dynamics and behavior of firms. I exploit the exogenous change in equity ...


    E-Print Network [OSTI]

    Haller, E.E.


    •^f-1? c^4--^ LBL-7996 HYDROGEN IN GERMANIUM E. E. HallerW-7405-ENG-48 LBL-7996 HYDROGEN IN GERMANIUM* E. E. Haller48. LBL-7996 Abstract Hydrogen is shown to form molecular

  7. Homelessness in California

    E-Print Network [OSTI]

    Quigley, John M.; Raphael, Steven; Smolensky, Eugene


    in-Publication Data Quigley, John M. Homelessness inMassachusetts, 1996. Quigley, John M. , A Decent Home:1, 2000, pp. 5388. Quigley, John M. and Steven Raphael,

  8. Graduate Program in Telecommunications

    E-Print Network [OSTI]

    Jiang, Huiqiang

    Communications analyst Network administrator Systems engineer Security officer MartinGraduate Program in Telecommunications and Networking #12;Why Telecommunications and Networking sophisticated network infrastructures. These network infrastructures bring functional challenges in network

  9. Defektlinien in Isingsystemen Diplomarbeit

    E-Print Network [OSTI]

    Usadel, K. D.

    Systems. Der Faktor 1 2 in (1.1) tritt auf, da man in der Doppelsumme jedes Spinpaar doppelt zählt. Im der Thermodynamik bekannt ist, tritt im thermischen Gleichgewicht bei einer Temperatur T eine

  10. Essays in financial economics

    E-Print Network [OSTI]

    Severino Daz, Felipe


    This thesis consists of three empirical essays in financial economics, examining the consequences of imperfect financial markets for households, small business and house prices. In the first chapter (co-authored with Meta ...

  11. Three essays in macroeconomics

    E-Print Network [OSTI]

    Farhi, Emmanuel


    Chapter 1 analyzes the theoretical and quantitative implications of optimal fiscal policy in a business cycle model with incomplete markets. I first consider the problem of a government facing expenditure shocks in an ...

  12. Essays in capital markets

    E-Print Network [OSTI]

    Papanikolaou, Dimitris, Ph. D. Massachusetts Institute of Technology


    In the first chapter, I provide evidence that investment-specific technological change is a source of systematic risk. In contrast to neutral productivity shocks, the economy needs to invest to realize the benefits of ...

  13. Essays in empirical finance

    E-Print Network [OSTI]

    Kumar, Pavithra Kamakshi


    The first chapter in my thesis investigates the association between selected hedge fund characteristics and persistence in performance over time. Analyzing TASS data from 1996-2006, I observe a positive correlation between ...

  14. Essays in development economics

    E-Print Network [OSTI]

    Keniston, Daniel Eben


    Chapter 1 looks at the empirical estimation of the welfare impacts of bargaining. Bargaining for retail goods is common in developing countries, but rare in the developed world. The welfare implications of this difference ...

  15. Credit derivatives in Brazil

    E-Print Network [OSTI]

    Rther, Henrique


    The amounts outstanding of credit derivatives have grown exponentially over the past years, and these financial intruments that allow market participants to trade credit risk have become very popular in Europe and in the ...

  16. Protest in Ethiopia

    E-Print Network [OSTI]

    Nicolas, Gildas


    thesis on "Christianity in Ethiopia". He has also written awith Local Religions in Ethiopia. GROUP AND A SINGLE by D.entrust the destiny of Ethiopia? Footnotes: Quoted i n R.

  17. In The News Feed

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

    how-iron-feels-the-heat May 18, 2015 In The News Feed Is The Elusive &039;Ideal&039; Electric-Car Battery Hiding In Plain Sight? http:www.greencarreports.comnews...

  18. The subjunctive in Spanish

    E-Print Network [OSTI]

    Solano, J. Miguel


    The various analyses for the subjunctive in Spanish that have been proposed can be classified into two major categories: syntactic and semantic. Syntactic analyses consist mainly of classifications of instances in which the subjunctive must be used...

  19. In situ measurement system

    DOE Patents [OSTI]

    Lord, D.E.


    A multipurpose in situ underground measurement system comprising a plurality of long electrical resistance elements in the form of rigid reinforcing bars, each having an open loop hairpin configuration of shorter length than the other resistance elements. The resistance elements are arranged in pairs in a unitized structure, and grouted in place in the underground volume. Measurement means are provided for obtaining for each pair the electrical resistance of each element and the difference in electrical resistance of the paired elements, which difference values may be used in analytical methods involving resistance as a function of temperature. A scanner means sequentially connects the resistance-measuring apparatus to each individual pair of elements. A source of heating current is also selectively connectable for heating the elements to an initial predetermined temperature prior to electrical resistance measurements when used as an anemometer.

  20. Muslim Leadership in America

    E-Print Network [OSTI]

    Mobeen, Noor 1982-


    Leadership has been a foundational component of any society, religion, culture, and human development. The purpose of this study was six fold: to examine the concept of leadership in Muslim communities in America, to observe the first...

  1. Jet substructure in ATLAS

    E-Print Network [OSTI]

    David W. Miller; for the ATLAS Collaboration


    Measurements are presented of the jet invariant mass and substructure in proton-proton collisions at sqrt{s} = 7 TeV with the ATLAS detector using an integrated luminosity of 37 pb-1. These results exercise the tools for distinguishing the signatures of new boosted massive particles in the hadronic final state. Two "fat" jet algorithms are used, along with the filtering jet grooming technique that was pioneered in ATLAS. New jet substructure observables are compared for the first time to data at the LHC. Finally, a sample of candidate boosted top quark events collected in the 2010 data is analyzed in detail for the jet substructure properties of hadronic "top-jets" in the final state. These measurements demonstrate not only our excellent understanding of QCD in a new energy regime but open the path to using complex jet substructure observables in the search for new physics.

  2. Endocytosis in filamentous fungi

    E-Print Network [OSTI]

    Kalkman, Edward R I C


    Endocytosis is little understood in filamentous fungi. For some time it has been controversial as to whether endocytosis occurs in filamentous fungi. A comparative genomics analysis between Saccharomyces cerevisiae and ...

  3. Essays in applied microeconomics

    E-Print Network [OSTI]

    Aron-Dine, Aviva


    This dissertation consists of three chapters on topics in applied microeconomics. In the first chapter. I investigate whether voters are more likely to support additional spending on local public services when they perceive ...

  4. Synchronization in complex networks

    SciTech Connect (OSTI)

    Arenas, A.; Diaz-Guilera, A.; Moreno, Y.; Zhou, C.; Kurths, J.


    Synchronization processes in populations of locally interacting elements are in the focus of intense research in physical, biological, chemical, technological and social systems. The many efforts devoted to understand synchronization phenomena in natural systems take now advantage of the recent theory of complex networks. In this review, we report the advances in the comprehension of synchronization phenomena when oscillating elements are constrained to interact in a complex network topology. We also overview the new emergent features coming out from the interplay between the structure and the function of the underlying pattern of connections. Extensive numerical work as well as analytical approaches to the problem are presented. Finally, we review several applications of synchronization in complex networks to different disciplines: biological systems and neuroscience, engineering and computer science, and economy and social sciences.

  5. Unity in Religion

    E-Print Network [OSTI]

    Wester, Jeremy


    in inter-religious dialogue. Challenges in the representation of exoteric forms of religious expression are considered and it is determined that, while it is impossible to completely ignore the exoteric representations of religious practice, the primary...

  6. Advertising in computer games

    E-Print Network [OSTI]

    Vedrashko, Ilya


    This paper suggests advertisers should experiment with in-game advertising to gain skills that could become vital in the near future. It compiles, arranges and analyzes the existing body of academic and industry knowledge ...

  7. Interface Magnetism in Multiferroics

    E-Print Network [OSTI]

    He, Qing


    1.2.1 Magnetism . . . . . . . . . . . . . . . . . . . 1.2.2domain walls . . . . . 3 Magnetism of domain walls in BiFeOof electrical control of magnetism in mixed phase BiFeO 3

  8. Safety in Buildings

    E-Print Network [OSTI]

    Hutcheon, N. B.

    Building codes are essentially sets of safety regulations in respect of structure, fire, and health. They were originally developed in response to frequently demonstrated hazards of structural collapse, catastrophic fires, ...

  9. Essays in financial economics

    E-Print Network [OSTI]

    Edmans, Alex


    This thesis consists of three essays in financial economics. Chapter 1 is entitled "Inside Debt." Existing theories advocate the use of cash and equity in executive compensation. However, recent empirical studies have ...

  10. Entanglement in Classical Optics

    E-Print Network [OSTI]

    Partha Ghose; Anirban Mukherjee


    The emerging field of entanglement or nonseparability in classical optics is reviewed, and its similarities with and differences from quantum entanglement clearly pointed out through a recapitulation of Hilbert spaces in general, the special restrictions on Hilbert spaces imposed in quantum mechanics and the role of Hilbert spaces in classical polarization optics. The production of Bell-like states in classical polarization optics is discussed, and new theorems are proved to discriminate between separable and nonseparable states in classical wave optics where no discreteness is involved. The influence of the Pancharatnam phase on a classical Bell-like state is deived. Finally, to what extent classical polarization optics can be used to simulate quantum information processing tasks is also discussed. This should be of great practical importance because coherence and entanglement are robust in classical optics but not in quantum systems.

  11. South Asians in Boston

    E-Print Network [OSTI]

    Masurkar, Alpita


    Boston has a rich and diverse history of immigrants. Right from the arrival of the Puritans in 1628-30 who established the earliest immigrant settlements in Boston, this region has attracted immigrants from different parts ...

  12. Systems building in architecture

    E-Print Network [OSTI]

    Tzannetakis, Charilaos Panayotis


    This work is an inquiry into the interventions of the systems design in the whole building process. At the beginning, three approaches which represent different points of view of interventions in production and use are ...


    E-Print Network [OSTI]

    ILLEGAL LOGGING IN INDONESIA THE ENVIRONMENTAL, ECONOMIC AND SOCIAL COSTS #12;ILLEGAL LOGGING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 II. Environmental Impacts of Illegal Logging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 #12;ILLEGAL LOGGING IN INDONESIA | 2 Executive Summary Indonesia's rainforests are the third

  14. Olefin Autoxidation in Flow

    E-Print Network [OSTI]

    Neuenschwander, Ulrich

    Handling hazardous multiphase reactions in flow brings not only safety advantages but also significantly improved performance, due to better mass transfer characteristics. In this paper, we present a continuous microreactor ...

  15. Historical change in coral reef communities in Caribbean Panama

    E-Print Network [OSTI]

    Cramer, Katie Lynn


    In Adaptive Radiations in Prehistoric Panama (OF Linares andIn Adaptive Radiations in Prehistoric Panama (OF Linares andIn Adaptive Radiations in Prehistoric Panama (OF Linares and

  16. Microcracking in fibrous composites

    E-Print Network [OSTI]

    Conrad, Nicholas


    MICROCRACKING IN FIBROUS COMPOSITES A Thesis by Nicholas Conrad Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August 1973 Major Subject...: Interdisciplinary Engineering MICROCRACKING IN FIBROUS COMPOSITES A Thesis by Nicholas Conrad Approved as to style and content by: (Chairman of Co~'tee) c. (Head o Department) Ix~ (Member) (Member) August 1973 ABSTRACT Microcracking in Fibrous...

  17. Corn Production in Texas.

    E-Print Network [OSTI]

    Collier, Jesse W. (Jesse Wilton); Rogers, John S. (John Sinclair)


    during wet seasons, and they may cause appreciable damage each year in the more humid sections. Hybrids such as Texas 24 and 30, which possess some resistance, shorrld be used where diseases and i~sects are a serious problem. The Texas hybrid corn... in this bulletin and recommendations are given for corn production in the different areas of the ' State. Numerous diseases and insects attack corn in Texas and are responsible for considerable damage to the crop. These organisms are especiallv prevalent...

  18. Innovation Concepts in Healthcare

    SciTech Connect (OSTI)



    AbstractDemographic change and advances in medical science pose increased challenges to healthcare systems globally: The economic basis is aging and thus health is becoming more and more a productivity factor. At the same time, with todays new communication possibilities the demand and expectations of effective medical treatment have been increased. This presentation will illustrate the need for the industrialization of healthcare in order to achieve highest results at limited budgets. Thereby, industrialization is not meaning the medical treatment based on the assembly line approach. Rather it is to recognize the cost of medical care as an investment with respective expectations on the return of the investment. Innovations in imaging and pharmaceutical products as well as in processes - that lead to similar medical results, but with lower efforts - are keys in such scenarios.BiographyProf. Dr. Hermann Requardt, 54, is a member of the Managing Board of Siemens AG and Chief Executive Officer of the Healthcare Sector. In addition he is the CTO of Siemens AG and Head of Corporate Technology, the central research department at Siemens.After completing his studies in physics and philosophy at the Darmstadt University of Technology and Johann Wolfgang Goethe University in Frankfurt and receiving a doctorate in biophysics, he worked at the Institute of Aerospace Medicine at the German Aerospace Center.In 1984 he joined the Medical Technology Group of Siemens AG, where he was responsible for projects in the Magnetic Resonance (MR) division. He was appointed head of the division in 1995. From 2001 to 2006, as a member of the Executive Management of the Medical Solutions Group, he was responsible for several areas, including technological development.In 2006 he became a Member of the Siemens Managing Board and head of Corporate Technology. He was additionally appointed as the Sector Healthcare CEO in 2008.Since 2006 he is an honorary professor in physics of the Johann Wolfgang Goethe University in Frankfurt.

  19. Undergraduate Study in Mathematics

    E-Print Network [OSTI]

    Areas of focus include Actuarial Science, Applied Mathematics, Business Mathematics, Operations Research, Mathematics Education and the dual majors in...

  20. Innovation Concepts in Healthcare

    ScienceCinema (OSTI)



    AbstractDemographic change and advances in medical science pose increased challenges to healthcare systems globally: The economic basis is aging and thus health is becoming more and more a productivity factor. At the same time, with today?s new communication possibilities the demand and expectations of effective medical treatment have been increased. This presentation will illustrate the need for the ?industrialization? of healthcare in order to achieve highest results at limited budgets. Thereby, industrialization is not meaning the medical treatment based on the assembly line approach. Rather it is to recognize the cost of medical care as an investment with respective expectations on the return of the investment. Innovations in imaging and pharmaceutical products as well as in processes - that lead to similar medical results, but with lower efforts - are keys in such scenarios.BiographyProf. Dr. Hermann Requardt, 54, is a member of the Managing Board of Siemens AG and Chief Executive Officer of the Healthcare Sector. In addition he is the CTO of Siemens AG and Head of Corporate Technology, the central research department at Siemens.After completing his studies in physics and philosophy at the Darmstadt University of Technology and Johann Wolfgang Goethe University in Frankfurt and receiving a doctorate in biophysics, he worked at the Institute of Aerospace Medicine at the German Aerospace Center.In 1984 he joined the Medical Technology Group of Siemens AG, where he was responsible for projects in the Magnetic Resonance (MR) division. He was appointed head of the division in 1995. From 2001 to 2006, as a member of the Executive Management of the Medical Solutions Group, he was responsible for several areas, including technological development.In 2006 he became a Member of the Siemens? Managing Board and head of Corporate Technology. He was additionally appointed as the Sector Healthcare CEO in 2008.Since 2006 he is an honorary professor in physics of the Johann Wolfgang Goethe University in Frankfurt.

  1. Women in STEM

    Broader source: [DOE]

    A page showcasing the great contributions of women in the energy sector and encouraging girls to continue studying STEM.

  2. Electroluminescence in photovoltaic cell

    E-Print Network [OSTI]

    Petraglia, Antonio; 10.1088/0031-9120/46/5/F01


    Here we propose two methods to get electroluminescence images from photovoltaic cells in a school or home lab.

  3. Entanglement in quantum catastrophes

    E-Print Network [OSTI]

    Clive Emary; Neill Lambert; Tobias Brandes


    We classify entanglement singularities for various two-mode bosonic systems in terms of catastrophe theory. Employing an abstract phase-space representation, we obtain exact results in limiting cases for the entropy in cusp, butterfly, and two-dimensional catastrophes. We furthermore use numerical results to extract the scaling of the entropy with the non-linearity parameter, and discuss the role of mixing entropies in more complex systems.

  4. Computational Linguistics in Egyptology

    E-Print Network [OSTI]

    Rosmorduc, Serge


    the interface of their web sites, or in collaboration withis an interesting example of web environment with a mainly

  5. Oscillations in glow discharges

    E-Print Network [OSTI]

    Prickett, Tom


    1950 CONTENTS Introduction ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 1 I. Review of Plasma Oscillations in Gas Discharges ? . . 2 II. Review of Relaxation Processes in Gas Discharges ? . 13 III. Report of Laboratory Investigation... 179540 LIST OF FIGURES Figure Page 1. Sketch of Plasma Space in which Electrons are given Displacements in the X-direction ? ? ? ? ? ? 5 2* Early Circuit Arrangement of Discharge Study ? ? ? ? ? 19 3, Flow Diagram of the Experimental System...

  6. Strangeness in Relativistic Astrophysics

    E-Print Network [OSTI]

    Jurgen Schaffner-Bielich; Stefan Schramm; Horst Stocker


    In these lecture notes, the role of strangeness in relativistic astrophysics of compact stars is addressed. The appearance of strange particles, as hyperons, kaons, and strange quarks, in the core of compact stars is examined and common features as well as differences are presented. Impacts on the global properties of compact stars and signals of the presence of exotic matter are outlined for the various strange phases which can appear in the interior at high densities.

  7. Magnetic susceptibility in QCD

    E-Print Network [OSTI]

    V. D. Orlovsky; Yu. A. Simonov


    Magnetic susceptibility in the deconfined phase of QCD is calculated in a closed form using a recent general expression for the quark gas pressure in magnetic field. Quark selfenergies are entering the result via Polyakov line factors and ensure the total paramagnetic effect, increasing with temperature. A generalized form of magnetic susceptibility in nonzero magnetic field suitable for experimental and lattice measurements is derived, showing a good agreement with available lattice data.

  8. Crying in the Wilderness

    E-Print Network [OSTI]

    Galef, Bennett G. Jr.


    Crying in the Wilderness Bennett G. Galef, Jr. McMastershould be addressed to Bennett G. Galef, Jr. Department of

  9. Spectral Functions in QFT

    E-Print Network [OSTI]

    Pisani, Pablo


    We present a pedagogical exposition of some applications of functional methods in quantum field theory: we use heat-kernel and zeta-function techniques to study the Casimir effect, the pair production in strong electric fields, quantum fields at finite temperature and beta-functions for a self-interacting scalar field, QED and pure Yang-Mills theories. The more recent application to the UV/IR mixing phenomenon in noncommutative theories is also discussed in this framework.

  10. Embodiment in social psychology

    E-Print Network [OSTI]

    Meier, Brian P.; Schnall, Simone; Schwarz, Norbert; Bargh, John, A.


    , highlighting some promising future directions. 1. The use of embodiment in social psychology Although embodied theories started gaining steam in the 1990s (Barsalou, 1999; Gibbs, 2006), approaches related to embodiment have a long tradition in social psychol... 1180. Higgins, E. T. (1996). Knowledge activation: Accessibility, applicability, and salience. In E. T. Higgins & A. W. Kruglanski (Eds.), Social psychology: Handbook of basic principles (pp. 133168). New York: Guilford Press. Izjerman, H., & Semin, G. (2010...

  11. Embodiment in social psychology

    E-Print Network [OSTI]

    Meier, Brian P.; Schnall, Simone; Schwarz, Norbert; Bargh, John, A.


    directions. The Use of Embodiment in Social Psychology Although embodied theories started gaining steam in the 1990s (Barsalou, 1999; Gibbs, 2006), approaches related to embodiment have a long tradition in social psychology. From addressing how... 13 Higgins, E. T. (1996). Knowledge activation: Accessibility, applicability, and salience. In E. T. Higgins & A. W. Kruglanski (Eds.), Social psychology: Handbook of basic principles (pp. 133-168). New York: Guilford Press. Izjerman, H., & Semin...

  12. In situ groundwater bioremediation

    E-Print Network [OSTI]

    Hazen, Terry C.


    J. W. Costerton. 1992. Enhanced oil-recovery - 3-dimensionalused for enhanced oil recovery in oil reservoirs (Cusack et.

  13. Optimization in Networks

    E-Print Network [OSTI]

    Adilson E. Motter; Zoltan Toroczkai


    The recent surge in the network modeling of complex systems has set the stage for a new era in the study of fundamental and applied aspects of optimization in collective behavior. This Focus Issue presents an extended view of the state of the art in this field and includes articles from a large variety of domains where optimization manifests itself, including physical, biological, social, and technological networked systems.

  14. Partnership in Computational Science

    SciTech Connect (OSTI)

    Huray, Paul G.


    This is the final report for the "Partnership in Computational Science" (PICS) award in an amount of $500,000 for the period January 1, 1993 through December 31, 1993. A copy of the proposal with its budget is attached as Appendix A. This report first describes the consequent significance of the DOE award in building infrastructure of high performance computing in the Southeast and then describes the work accomplished under this grant and a list of publications resulting from it.

  15. Interaction in musical time

    E-Print Network [OSTI]

    Himberg, Tommi


    plots . . . . . . . . . . . . . . . . . . . . 268 9 List of Tables 6.1 Intraclass correlation . . . . . . . . . . . . . . . . . . . . . . . 143 7.1 Summary of tapping partners . . . . . . . . . . . . . . . . . . 162 7.2 Factorial design... , in order to develop the cooperative tapping setup used in the human vs. computer partner experiment. These were mainly exercises in experimental design and data analysis. The research questions posed in these studies are still valid, though the data so far...

  16. In this document: Freshmanadmissiondecisionoverview

    E-Print Network [OSTI]

    Blanchette, Robert A.

    In this document: Freshmanadmissiondecisionoverview Academicprofileoffall2012 and Human Development Liberal Arts Management (Carlson School of) Science and Engineering #12;Frequently

  17. In this document: Freshmanadmissiondecisionoverview

    E-Print Network [OSTI]

    Blanchette, Robert A.

    In this document: Freshmanadmissiondecisionoverview Academicprofileoffall2012, Agricultural and Natural Resource Sciences Education and Human Development Liberal Arts Management (Carlson

  18. in Economics and Finance

    E-Print Network [OSTI]

    van der Torre, Leon

    Master's in Economics and Finance #12;2 3 "A research-centred institution with a personal REASONS TO STUDY The Master's in Economics and Finance programme targets students wishing to obtain a comprehensive and rigorous education in Economics and Finance. It emphasizes the complementary nature

  19. discoveries in drugs and

    E-Print Network [OSTI]

    Glasser, Benjamin J.

    Engineering Training Program (PETP) was initiated in 1995 and was the first in the nation to formally combineD, is a faculty member and director of the Pharmaceutical Engineering Training Program (PETP) in the Department the country funded by the National Science Foundation. PETP is a joint venture of the De- partment of Chemical

  20. Anaerobic Hydrocarbon Degradation in

    E-Print Network [OSTI]

    California at Berkeley, University of

    Anaerobic Hydrocarbon Degradation in Petroleum-Contaminated Harbor Sediments under Sulfate of iron(III) oxide to stimulate in- situ hydrocarbon degradation in anaerobic petroleum- contaminated did not stimulate anaerobic hydrocarbon oxidation. Exposure of the sediment to air [to reoxidize Fe

  1. Stability and Complexity in

    E-Print Network [OSTI]

    Landweber, Laura

    and complexity of a commu- nity of interacting plants and animals, following the food web as a clue. Contrary in power. Stability and Complexity in Model Ecosystems played a key role in introducing nonlinear thinking, and current threats to biodiversity have made questions about the role of ecosystem complexity

  2. Homelessness in California

    E-Print Network [OSTI]

    Sekhon, Jasjeet S.

    Homelessness in California · · · John M. Quigley Steven Raphael Eugene Smolensky with Erin Mansur-in-Publication Data Quigley, John M. Homelessness in California / John M. Quigley, Steven Raphael, Eugene Smolensky. p. The authors of the present volume--John Quigley, Stephen Raphael, and Eugene Smolensky, all from the Goldman

  3. Aging in community

    E-Print Network [OSTI]

    Fay, Justin (Justin Thomas)


    Baby Boomers are on the brink of retirement. According to U.S. Census Bureau projections, the number of people aged 65 and over will more than double in the coming decades, growing from 35 million in 2000 to 72 million in ...

  4. Correspondences DDT resistance in

    E-Print Network [OSTI]

    Buckling, Angus

    Magazine R587 Correspondences DDT resistance in flies carries no cost Caroline McCart1, Angus to carry a cost in the absence of pesticide and consequently not to spread to fixation [1,2]. However, DDT resistance in Drosophila melanogaster (DDT-R) is approaching fixation globally, long after withdrawl of DDT

  5. Recommendation in Social Networks

    E-Print Network [OSTI]

    Ester, Martin

    Recommendation in Social Networks Martin Ester Simon Fraser University Tutorial at RecSys 2013 October 12 , 2013 #12;Martin Ester: Recommendation in Social Networks, Tutorial at RecSys 2013 2 Outline Introduction Recommendation in social networks Memory based approaches for item recommendation Model

  6. Extinction curves in AGN

    E-Print Network [OSTI]

    B. Czerny


    The presence of the dust in the circumnuclear region strongly affects our view of the nucleus itself. The effect is strong in type 2 objects but weaker effect is likely to be present in type 1 objects as well. In these objects a correction to the observed optical/UV spectrum must be done in order to recover the intrinsic spectrum of a nucleus. The approach based on the extinction curve is convenient for that purpose so significant effort has been recently done in order to determine the extinction curve for the circumnuclear material. It seems clear that the circumnuclear dust is different from the average properties of the dust in the Interstellar Medium in our galaxy: the well known 2175 A feature is weak or absent in AGN nuclear dust, and the extinction curve at shorter wavelength does not seem to be rising as steeply. The circumnuclear dust is therefore more similar to SMC dust, or more likely, to the dust in very dense molecular clouds in our Galaxy. However, the exact shape of the extinction curve in the far UV is still a matter of debate, and various effects are difficult to disentangle.

  7. Hispanic Theatre in Kansas

    E-Print Network [OSTI]


    96 LATIN AMERICAN THEATRE REVIEW Hispanic Theatre in Kansas The Fanlights (Los soles truncos), by the late Rene Marqus, was performed in English translation at the University of Kansas, in Lawrence, April 10-12 and 17-21, 1979. The play...

  8. The cartel in retreat

    E-Print Network [OSTI]

    Adelman, Morris Albert


    In 1981, the price of oil was $34 in current dollars ($50 at 1992 price levels). The consensus was that it would keep rising toward the cost of synthetic crude oil or some such long-run ceiling. In fact, the cartel had ...

  9. programs in climate change

    E-Print Network [OSTI]

    existing programs in climate change science and infrastructure. The Laboratory has a 15- year history in climate change science. The Climate, Ocean and Sea Ice Modeling (COSIM) project develops and maintains advanced numerical models of the ocean, sea ice, and ice sheets for use in global climate change

  10. Expert systems in transportation

    SciTech Connect (OSTI)

    O'Leary, K.P.


    The 5 papers in the report deal with the following areas: Knowledge representation and software selection for expert-systems design; Expert-system architecture for retaining-wall design; Development of expert-systems technology in the California Department of Transportation; Development of an expert system to assist in the interactive graphic transit system design process; Expert systems development for contingency transportation planing.

  11. Recent Trends in Car Usage in Advanced Economies - Slower Growth...

    Open Energy Info (EERE)

    Trends in Car Usage in Advanced Economies - Slower Growth Ahead? Jump to: navigation, search Tool Summary LAUNCH TOOL Name: Recent Trends in Car Usage in Advanced Economies -...

  12. Gauging Improvements in Urban Building Energy Policy in India

    E-Print Network [OSTI]

    Williams, Christopher


    Urban Building Energy Policy in India Christopher WilliamsUrban Building Energy Policy in India Christopher Williamsefficiency policies and programs in India are in an active

  13. Regulation and Moral Hazard in Forest Concessions in Brazil

    E-Print Network [OSTI]

    Balbinotto Neto, Gicomo; Tillmann, Eduardo A; Ratnieks, Ianes


    and Forest Concessions in Brazil. Planejamento e Polticaswelfare maximization in Brazil. Rio de Janeiro: IPEA, Forest Concessions in Brazil Eduardo A. Tillmann MS.

  14. Shared Space vs. In-Unit Upgrades in Multifamily Buildings |...

    Energy Savers [EERE]

    Shared Space vs. In-Unit Upgrades in Multifamily Buildings Shared Space vs. In-Unit Upgrades in Multifamily Buildings Better Buildings Neighborhood Program Multifamily Peer...

  15. PACCAR CRADA: Experimental Investigation in Coolant Boiling in...

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

    PACCAR CRADA: Experimental Investigation in Coolant Boiling in a Half-Heated Circular Tube PACCAR CRADA: Experimental Investigation in Coolant Boiling in a Half-Heated Circular...

  16. Equine in vitro fertilization

    E-Print Network [OSTI]

    Vasquez C., Juan Carlos


    reported on in-vitro maturation of oocytes (IVM) and IVF. Some reports indicating success include: 1) in vitro maturation/in-vitro fertilization has been achieved (Del Campo et al. , 1990; Zhang et al. , 1990; Ellington et al. , 1992), yet... then other reports have been published claiming different rates of IVF success (Zhang et al. , 1990; Del Campo et al. , 1990; Ellington et al. , 1992) including the first foal born after fertilization in-vitro of oocytes matured in-vivo (Palmer et al...

  17. Specialty Vegetables in Texas.

    E-Print Network [OSTI]

    Longbrake, Thomas D.; Baker, Marvin L.; Cotner, Sam; Parsons, Jerry; Roberts, Roland; Stein, Larry


    flowers may be stored a short time in plastic bags in refrigeration. Freeze whole small flowers in ice rings or cubes. \\ ' \\."" Edible Podded Peas, Snow Peas and Sugar Snaps Description. Pods of snow peas are flat and thin with the bulge of tiny... dllce their large roots after several years of growth. They are commonly found in frost-free regions. [n Texas, plant seed in the early spring and harvest small tubers before the first killing frost. The root or tuber initiation and development...

  18. Gilgit in Ancient Times

    E-Print Network [OSTI]

    Prakash, Buddha


    and the latter also sent his envoy, Tch'a-tcho-na-se-mo me-cheng, to express his gratitude to the Chinese court. In 733 Mo-kin-mang is said to have sent another envoy to China, on his death his son Nan-ni assumed power. He also died soon and in 641 his elder... there which played a very significant part in history. That the state of Gilgit became a great power in the seventh and eighth centuries is known from an inscription found one mile south of Hatun on the right bank of the Ishkuman river in the Gilgit Agency...

  19. Inflation in a web

    SciTech Connect (OSTI)

    Li Sheng; Piao Yunsong [College of Physical Sciences, Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Liu Yang [College of Physical Sciences, Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Department of Physics, Shandong University, Jinan 250100 (China)


    In a given path with multiple branches, in principle, it can be expected that there are some fork points, where one branch is bifurcated into different branches, or various branches converge into one or several branches. In this paper, it is shown that if there is a web formed by such branches in a given field space, in which each branch can be responsible for a period of slow roll inflation, a multiverse separated by a domain wall network will come into being, some of which might correspond to our observable universe. We discuss this scenario and show possible observations of a given observer at late time.


    SciTech Connect (OSTI)



    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  1. Secular evolution in galaxies

    E-Print Network [OSTI]

    F. Combes


    New observations in favour of a significant role of secular evolution are reviewed: central star formation boosted in pseudo-bulge barred galaxies, relations between bulge and disk, evidence for rejuvenated bulges. Numerical simulations have shown that secular evolution can occur through a cycle of bar formation and destruction, in which the gas plays a major role. Since bars are weakened or destroyed in gaseous disks, the high frequency of bars observed today requires external cold gas accretion, to replenish the disk and allow a new bar formation. The rate of gas accretion from external filaments is compatible with what is observed in cosmological simulations.

  2. Clustering in nuclear environment

    E-Print Network [OSTI]

    G. Rpke


    The properties of few-body clusters (mass number $A \\le 4$) are modified if they are immersed in a nuclear medium. In particular, Pauli blocking that reflects the antisymmetrization of the many-body wave function is responsible for the medium modification of light clusters and the dissolution with increasing density. A more consistent description is given with takes also the contribution of correlations in the continuum into account. The relation between cluster formation in warm dense matter and in nuclear structure is discussed.

  3. Transformations in Milton's "Comus"

    E-Print Network [OSTI]

    Yu, Hung-Chih


    celestial hall, ana. with him Pallas Athene, spreading horror from her exposed Gorgon shield, So the child of Juno fell upon Aegean Lemnos, where he was tossed down from the sacred threshold oi' heaven. And you also, Phoebus Apollo, shall share the fate... native city and not to be interested in the least in returning to the "sedgy Cam" (p. 8) and the charmless bare fields uncongenial to the worshippers of Apollo. He rejoices in the books "which are my life" (p. 8), in plays, and in the sight of lovely...

  4. In other news

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn Other News Community Connections: Your link toinaInInInIn

  5. Gabriel Ulici Laurea magistrale in ingegneria in-

    E-Print Network [OSTI]

    Di Pillo, Gianni

    Personali Nome Cognome Gabriel Ulici Data di nascita 23 Settembre 1987 Luogo di nascita Satu Mare, Romania- versità Rumeno­Americana, Bucarest, Romania, ISCED 5. Set 2002­Lug 2006 Diploma di Scuola Superiore in Informatica, Collegio Nazionale "Ioan Slavici", Satu Mare, Romania, ISCED 3. Interessi di Ricerca

  6. Women in Physics in the United States

    E-Print Network [OSTI]

    Ito, Atsushi

    Friendly Edge (including articles by Prof. Mary Ann Mason) The Gender Equity Project (including articles by Prof. Virginia Valian): Women Don't Ask: ... women's representation and advancement in academic STEM positions are affected by many external factors

  7. Geothermal development in Australia

    SciTech Connect (OSTI)

    Burns, K.L. [Los Alamos National Lab., NM (United States); Creelman, R.A. [Creelman (R.A.) and Associates, Sydney, NSW (Australia); Buckingham, N.W. [Glenelg Shire Council, Portland, VIC (Australia); Harrington, H.J. [Australian National Univ., Canberra, ACT (Australia)]|[Sydney Univ., NSW (Australia)


    In Australia, natural hot springs and hot artesian bores have been developed for recreational and therapeutic purposes. A district heating system at Portland, in the Otway Basin of western Victoria, has provided uninterrupted service for 12 Sears without significant problems, is servicing a building area of 18 990 m{sup 2}, and has prospects of expansion to manufacturing uses. A geothermal well has provided hot water for paper manufacture at Traralgon, in the Gippsland Basin of eastern Victoria. Power production from hot water aquifers was tested at Mulka in South Australia, and is undergoing a four-year production trial at Birdsville in Queensland. An important Hot Dry Rock resource has been confirmed in the Cooper Basin. It has been proposed to build an HDR experimental facility to test power production from deep conductive resources in the Sydney Basin near Muswellbrook.

  8. Research in particle theory

    SciTech Connect (OSTI)

    Mansouri, F.; Suranyi, P; Wijewardhana, L.C.R.


    In the test particle approximation, the scattering amplitude for two-particle scattering in (2+1)-dimensional Chern-Simons-Witten gravity and supergravity was computed and compared to the corresponding metric solutions. The formalism was then extended to the exact gauge theoretic treatment of the two-particle scattering problem and compared to 't Hooft's results from the metric approach. We have studied dynamical symmetry breaking in 2+1 dimensional field theories. We have analyzed strong Extended Technicolor (ETC) models where the ETC coupling is close to a critical value. There are effective scalar fields in each of the theories. We have worked our how such scalar particles can be produced and how they decay. The {phi}{sup 4} field theory was investigated in the Schrodinger representation. The critical behavior was extracted in an arbitrary number of dimensions in second order of a systematic truncation approximation. The correlation exponent agrees with known values within a few percent.

  9. Temperature in the Throat

    E-Print Network [OSTI]

    Dariush Kaviani; Amir Esmaeil Mosaffa


    We study the temperature of extended objects in string theory. Rotating D-branes in warped Calabi-Yau throats have induced metrics with thermal horizons and Hawking temperatures a la Unruh effect. We solve the equations of motion for slow rotating probe branes and derive their induced metrics in the UV/IR solutions of warped conifold throats. Our analysis shows that horizons and temperatures of expected features form on the world volume of the rotating probe brane in terms of conserved charges in the UV solutions of the conifold throat. In certain limits, we find world volume horizons and temperatures of the form similar to those of rotating probes in the AdS throat.


    SciTech Connect (OSTI)

    BERG, J.S.


    Fixed field alternating gradient accelerators have many features which require careful modeling in simulation. They accept beams over an extremely large momentum range, generally at least a factor of 2. They often use magnets whose lengths are comparable to their apertures. The beam often makes large angles with respect to the magnet axis and pole face normal. In some applications (muons in particular), the beam occupies a substantial fraction of the magnet aperture. The longitudinal dynamics in these machines often differ significantly from what one finds in more conventional machines such as synchrotrons. These characteristics require that simulation codes be careful to avoid inappropriate approximations in describing particle motion in FFAGs. One must properly treat the coordinate system geometry independently from the magnetic fields. One cannot blindly assume that phase space variables are small. One must take magnet end fields properly into account. Finally, one must carefully consider what it means to have a ''matched'' distribution that is injected into these machines.

  11. Photoneutron reactions in astrophysics

    SciTech Connect (OSTI)

    Varlamov, V. V., E-mail:; Ishkhanov, B. S.; Orlin, V. N.; Peskov, N. N.; Stopani, K. A. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)


    Among key problems in nuclear astrophysics, that of obtaining deeper insight into the mechanism of synthesis of chemical elements is of paramount importance. The majority of heavy elements existing in nature are produced in stars via radiative neutron capture in so-called s- and r processes, which are, respectively, slow and fast, in relation to competing ?{sup ?}-decay processes. At the same time, we know 35 neutron-deficient so-called bypassed p-nuclei that lie between {sup 74}Se and {sup 196}Hg and which cannot originate from the aforementioned s- and r-processes. Their production is possible in (?, n), (?, p), or (?, ?) photonuclear reactions. In view of this, data on photoneutron reactions play an important role in predicting and describing processes leading to the production of p-nuclei. Interest in determining cross sections for photoneutron reactions in the threshold energy region, which is of particular importance for astrophysics, has grown substantially in recent years. The use of modern sources of quasimonoenergetic photons obtained in processes of inverse Compton laser-radiation scattering on relativistic electronsmakes it possible to reveal rather interesting special features of respective cross sections, manifestations of pygmy E1 and M1 resonances, or the production of nuclei in isomeric states, on one hand, and to revisit the problem of systematic discrepancies between data on reaction cross sections from experiments of different types, on the other hand. Data obtained on the basis of our new experimental-theoretical approach to evaluating cross sections for partial photoneutron reactions are invoked in considering these problems.

  12. Jet physics in ALICE

    E-Print Network [OSTI]

    C. Loizides


    This work aims at the performance of the ALICE detector for the measurement of high-energy jets at mid-pseudo-rapidity in ultra-relativistic nucleus--nucleus collisions at LHC and their potential for the characterization of the partonic matter created in these collisions. In our approach, jets at high energy with E_{T}>50 GeV are reconstructed with a cone jet finder, as typically done for jet measurements in hadronic collisions. Within the ALICE framework we study its capabilities of measuring high-energy jets and quantify obtainable rates and the quality of reconstruction, both, in proton--proton and in lead--lead collisions at LHC conditions. In particular, we address whether modification of the jet fragmentation in the charged-particle sector can be detected within the high particle-multiplicity environment of the central lead--lead collisions. We comparatively treat these topics in view of an EMCAL proposed to complete the central ALICE tracking detectors. The main activities concerning the thesis are the following: a) Determination of the potential for exclusive jet measurements in ALICE. b) Determination of jet rates that can be acquired with the ALICE setup. c) Development of a parton-energy loss model. d) Simulation and study of the energy-loss effect on jet properties.

  13. MPhys (Hons) in Astrophysics MPhys (Hons) in Physics

    E-Print Network [OSTI]

    Sussex, University of

    Essentials Courses MPhys (Hons) in Astrophysics MPhys (Hons) in Physics BSc (Hons) in Physics MPhys (Hons) in Physics (research placement) MPhys (Hons) in Physics with Astrophysics BSc (Hons) in Physics with Astrophysics MPhys (Hons) in Theoretical Physics BSc (Hons) in Theoretical Physics Foundation year for UK

  14. Cosmic rays in astrospheres

    E-Print Network [OSTI]

    Scherer, Klaus; Bomans, Dominik; Ferreira, Stefan; Fichtner, Horst; Kleimann, Jens; Strauss, Dutoit; Weis, Kerstin; Wiengarten, Tobias; Wodzinski, Thomas


    Cosmic rays passing through large astrospheres can be efficiently cooled inside these "cavities" in the interstellar medium. Moreover, the energy spectra of these energetic particles are already modulated in front of the astrospherical bow shocks. We study the cosmic ray flux in and around lambda Cephei as an example for an astrosphere. The large-scale plasma flow is modeled hydrodynamically with radiative cooling. We studied the cosmic ray flux in a stellar wind cavity using a transport model based on stochastic differential equations. The required parameters, most importantly, the elements of the diffusion tensor, are based on the heliospheric parameters. The magnetic field required for the diffusion coefficients is calculated kinematically. We discuss the transport in an astrospheric scenario with varying parameters for the transport coefficients. We show that large stellar wind cavities can act as sinks for the galactic cosmic ray flux and thus can give rise to small-scale anisotropies in the direction to...

  15. Entanglement in neutrino oscillations

    E-Print Network [OSTI]

    Massimo Blasone; Fabio Dell'Anno; Silvio De Siena; Fabrizio Illuminati


    Flavor oscillations in elementary particle physics are related to multi-mode entanglement of single-particle states. We show that mode entanglement can be expressed in terms of flavor transition probabilities, and therefore that single-particle entangled states acquire a precise operational characterization in the context of particle mixing. We treat in detail the physically relevant cases of two- and three-flavor neutrino oscillations, including the effective measure of CP violation. We discuss experimental schemes for the transfer of the quantum information encoded in single-neutrino states to spatially delocalized two-flavor charged lepton states, thus showing, at least in principle, that single-particle entangled states of neutrino mixing are legitimate physical resources for quantum information tasks.

  16. Livestock Auctions in Texas.

    E-Print Network [OSTI]

    McKenzie, Travis M. (Travis McDonald); Brotherton, Charles B. (Charles Benjamin); McNeely, John G.


    livestock needed by farmers are sold through the local market. This bulletin describes the local auctions in Texas with empha- sis on facilities, consignments, purchases, method of sale, trans- portation services and other important factors. The auctions... are I described by areas to permit comparisons of regional character- istics. The data summarized in the study pertain to 37 auctions / selected in 4 major geographical areas. The physical data are I supplemented by records of 35,000 sales...

  17. Frontiers in Cosmic Rays

    E-Print Network [OSTI]

    Luis A. Anchordoqui; Charles D. Dermer; Andreas Ringwald


    This rapporteur review covers selected results presented in the Parallel Session HEA2 (High Energy Astrophysics 2) of the 10th Marcel Grossmann Meeting on General Relativity, held in Rio de Janeiro, Brazil, July 2003. The subtopics are: ultra high energy cosmic ray anisotropies, the possible connection of these energetic particles with powerful gamma ray bursts, and new exciting scenarios with a strong neutrino-nucleon interaction in the atmosphere.

  18. Astronomy in Argentina

    E-Print Network [OSTI]

    Muriel, Hernn


    This article analyses the current state of Astronomy in Argentina and describes its origins. We briefly describe the institutions where astronomical research takes place, the observational facilities available, the training of staff and professionals, and the role of the institutions in scientific promotion. We also discuss the outreach of Astronomy towards the general public, as well as amateur activities. The article ends with an analysis of the future prospects of astronomy in Argentina.

  19. Symmetries in Integer Programs

    E-Print Network [OSTI]

    Bdi, R


    The notion of symmetry is defined in the context of Linear and Integer Programming. Symmetric integer programs are studied from a group theoretical viewpoint. We investigate the structure of integer solutions of integer programs and show that any integer program on n variables having an alternating group A_n as a group of symmetries can be solved in linear time in the number of variables.

  20. Barley Production in Texas.

    E-Print Network [OSTI]

    Dunkle, P. B. (Paul Burtch); Atkins, Irvin Milburn


    grain sorghum, but should be ground for all classes of livestock. Barley is less subject to attack by rust than other small grains due to its early maturity. The common dimsieases, smut and slxipe, may be can- trolled by seed treatment. CONTENTS... Experimental Results ....................................... 16 Substation No. 6, Denton, Texas 16 Yields of Barley in Fall Sown Field Plat Trials 16 Yields of Barley in Fall Sown Nursery Plat Trials _-__----------- 19 Yields of Barley in Spring Sown...

  1. Graphics insertion in TEX

    E-Print Network [OSTI]

    Kattawar, Gregory Williford


    GRAPHICS INSERTION IN ~ A Thesis by GREGORY WILLIFORD KATTAWAR Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1989 Major Subject...: Computer Science GRAPHICS INSERTION IN TgX A Thesis by GREGORY WILLIFORD KATTAWAR Approved as to style and content by: S. Bart Childs (Chair of Committee) Norman W. Naugle (Member) Udo W. ooch (Member) Richard A. Volz (Head of Department...

  2. Viscosity in modified gravity

    E-Print Network [OSTI]

    Iver Brevik


    A bulk viscosity is introduced in the formalism of modified gravity. It is shown that, on the basis of a natural scaling law for the viscosity, a simple solution can be found for quantities such as the Hubble parameter and the energy density. These solutions may incorporate a viscosity-induced Big Rip singularity. By introducing a phase transition in the cosmic fluid, the future singularity can nevertheless in principle be avoided.

  3. Oak Poisoning in Livestock.

    E-Print Network [OSTI]

    Dollahite, J. W.; Housholder, G. T.; Camp, B. J.


    ..-.......----------- - .............................. 3 . . Cllnlcal Signs and Lesions 4 . . Recent Studies on Oak Toxicity 4 Evaluations of Possible Antidotes ................................................................ 5 Methods of Chemical Control of Oak 8 Conclusions... this figure. Oak Poisoning in Livestock In 1936, Boughton and Hardy (3) reported severe losses among cattle and sheep eating Q. d?~~-u~dii var breviloba in the Edwards Plateau region of Texas. Q. gumbellii was reported by Marsh et al. (16) to be toxic...

  4. Steam Champions in Manufacturing

    E-Print Network [OSTI]

    Russell, C.

    for human resource management. Under-trained apprentices are easier on the payroll, but a corresponding loss in productivity is the trade off. It is desirable to develop these personnel, assuming they can be retained after completing their training... performance contractor, or managing a staff with a few key professionals and a complement of apprentices who essentially learn on the job. In the best of circumstances, the stearn champion can plan staffing needs in response to statutory certification...

  5. Allies in Sport Organizations

    E-Print Network [OSTI]

    Melton, Elizabeth


    Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOSPHY Approved by: Chair of Committee, George B. Cunningham Committee Members, Kathi Miner Gregg... Chair of Advisory Committee: Dr. George B. Cunningham Employee support is a key factor in creating more welcoming and accepting work environments for lesbian, gay, bisexual, and transgender (LGBT) individuals in sport. As such, organizations need...

  6. Astronomy in Ukraine

    E-Print Network [OSTI]

    Ya. V. Pavlenko; I. B. Vavilova; T. Kostiuk


    The current and prospective status of astronomical research in Ukraine is discussed. A brief history of astronomical research in Ukraine is presented and the system organizing scientific activity is described, including astronomy education, institutions and staff, awarding higher degrees/titles, government involvement, budgetary investments and international cooperation. Individuals contributing significantly to the field of astronomy and their accomplishments are mentioned. Major astronomical facilities, their capabilities, and their instrumentation are described. In terms of the number of institutions and personnel engaged in astronomy, and of past accomplishments, Ukraine ranks among major nations of Europe. Current difficulties associated with political, economic and technological changes are addressed and goals for future research activities presented.

  7. Pecan Propagation in Texas.

    E-Print Network [OSTI]

    Swallow, A. P.


    PECAN PROPAGATION IN TEXAS I SOIL AND CLIMATIC REQ:UIREMENTS The ideal condition for pecan production is to have the roots of the tree in perpetual, moderate moisture and the top in constant sunshine. Good pecan land should be fertile, deep, loose... it should be much deeper. Shallow soils cannot be relied upon to pro duce regular crops. Tight land prevents the growth of an extended root system, and is too uneven in its moisture content. The wood growing period of a pecan tree extends froInt the opening...

  8. (Ionization in liquids)

    SciTech Connect (OSTI)

    Not Available


    This document describes charge transport following ionization of model liquids and how this process may be important in carcinogenesis. 15 refs., 2 figs., 4 tabs. (MHB)

  9. Scheduling in Multiprocess Systems

    E-Print Network [OSTI]

    Dou, Ji Adam


    In RTSS, Lisbon, Portugal, [46] Facebook. Facebook. [47] Facebook.Facebook info.php? statistics, 2011. statistics. http://

  10. In China's Mirror

    E-Print Network [OSTI]

    Barros de Castro, Antnio


    of California, Berkeley In Chinas Mirror * Antnio Barrosthe article No Espelho da China, which originally appearedThomas, Produtos Baratos da China Facilitam a Vida de

  11. This Week in Petroleum

    Gasoline and Diesel Fuel Update (EIA)

    the primary space heating fuel has declined by 16%, reducing the cold weather distillate demand response in the Northeast (Figure 2). Distillate demand for power generation also...

  12. Computer Forensics In Forensis

    E-Print Network [OSTI]

    Peisert, Sean; Bishop, Matt; Marzullo, Keith


    U.N. In Proceedings of CMAD IV: Computer Misuse and Anomaly4] J. P. Anderson. Computer Security Threat Monitoring andof the Fifth Annual Computer Security Applications

  13. Adventures in Public Data

    E-Print Network [OSTI]

    Zaharevitz, Daniel W


    , and in 1997 that wasnt exactly the most widespread notion in the world. I also presented web stats for how many pages were accessed. The number of hits weren't that impressive by todays standards but again youre talking with people that were used... us to test a compound was the supplier would send in a picture, would send in a piece of paper, a graphic so we did not have an electronic interaction between the requester and our systems; it was all us doing transfers from some kind of picture...

  14. Global developments in MTBE

    SciTech Connect (OSTI)

    Feller, L.W. [CMAI, Houston, TX (United States)


    This paper is intended to provide an overview of some of the recent developments in MTBE demand growth worldwide and the impact of these developments on MTBE demand in the future. It provides a perspective of the influence of developments in the US on the worldwide MTBE markets. The public`s outcry regarding oxygenates in gasoline, and specifically MTBE, that has been evolving in the US during the past several months is in response to a politically mandated requirement for a fuel that contains oxygen that is provided by MTBE or ethanol. This public unrest had negatively impacted the market price for MTBE at the time this paper was being prepared. However, the author believes that MTBE, because of its clean octane capabilities, will continue to be used as an octane blendstock for gasoline in increasing quantities worldwide as we move through lead phasedown in West Europe and other countries that are experiencing pollution problems relating to exhaust emissions from internal combustion engines. The objectives of this paper are as follows: review developments in MTBE demand 1990--2000; identify regions where MTBE demand growth will occur; review production growth for MTBE, both historical and forecast; examine world trade patterns during the period; assess methanol demand growth during the period; analyze MTBE`s regional price bias; and provide a forecast of future MTBE price trends.

  15. Caustics in turbulent aerosols

    E-Print Network [OSTI]

    M. Wilkinson; B. Mehlig


    Networks of caustics can occur in the distribution of particles suspended in a randomly moving gas. These can facilitate coagulation of particles by bringing them into close proximity, even in cases where the trajectories do not coalesce. We show that the long-time morphology of these caustic patterns is determined by the Lyapunov exponents lambda_1, lambda_2 of the suspended particles, as well as the rate J at which particles encounter caustics. We develop a theory determining the quantities J, lambda_1, lambda_2 from the statistical properties of the gas flow, in the limit of short correlation times.

  16. Ergonomics in the Biosciences

    E-Print Network [OSTI]

    Janowitz, Ira


    Gilson (ND) Laboratory ergonomics: Things you should knowMason E, Dukes S (2003 ). Ergonomics and cytotechnologists:Ergonomics in the Biosciences Ira Janowitz, PT, CPE Lawrence

  17. Prehistoric sanctuaries in Daunia

    E-Print Network [OSTI]

    Antonello, E; Tunzi, A M; Zupone, M Lo


    Daunia is a region in northern Apulia with many interesting archaeological sites, particularly of the Neolithic and Bronze Age. Beginning from the fifth millennium BC, the farmers living in the wide plain of Daunia dug hypogea and holes in sites that could be considered prehistoric sanctuaries. The characteristics of the rows of holes indicate a ritual use, and the archaeologists tend to exclude other applications, such as post holes and cultivations. The rows have possibly an astronomical orientation, and in the sanctuary discovered near Ordona, some stars of the Centaurus-Crux group (may be alpha Centauri itself) could have been used as targets. In past centuries, astronomers and scholars have remarked this spectacular region of the sky, and its possible relevance for the ancient civilizations was pointed out for example by G.V. Schiaparelli in 1903. In his work on the astronomy in the Old Testament, he mentioned in particular the observations of the astronomer W.S. Jacob and of other scholars. It would be ...

  18. EMSL - In situ catalysis

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

    situ-catalysis en New generation NMR bioreactor coupled with high-resolution NMR spectroscopy leads to novel discoveries in Moorella http:www.emsl.pnl.govemslwebpublications...

  19. Visual Arts in Microfiche

    E-Print Network [OSTI]

    Levine, Stuart


    can then use it as a guide to go from place to place. Good in theory, but not in practice, for the thick plastic plaque kept catching on the guide mechanism, and within five minutes mine had become bent at the edges and thus prone to foul... the crudity of the mechanism, it would in practice be impossible not to jiggle the captions into view from time to time). But the result, for someone using this material in order to find something, is infuriating. With no central guide to tell you what each...

  20. Essays in Energy Economics

    E-Print Network [OSTI]

    Spurlock, Cecily Anna


    is apparent in the electricity consumption behavior ofuncorrelated with electricity consumption on any given day.correlated with electricity consumption, 15 I compare the

  1. Adventures in Infectious Diseases

    ScienceCinema (OSTI)

    Fisher-Hoch, Susan [University of Texas School of Public Health


    Dr. Susan Fisher-Hoch, Virologist and Epidemiologist, will discuss her research and travels associated with viral hemorrhagic fevers. From the Ebola outbreak in Reston, Virginia to outbreaks of Crimean Congo Hemorrhagic Fever in South Africa, Senegal, and Saudi Arabia, Dr. Fisher-Hoch has studied and tracked the pathophysiology of these viral diseases. These studies have led her from the Center for Disease Control in the United States, to Lyon, France where she was instrumental in designing, constructing, and rendering operational a laboratory capable of containing some of the world's most dangerous diseases.


    E-Print Network [OSTI]

    Murphy, M.


    chemical elements uranium zirconium niobium beryllium rarerare earths, niobium, zirconium, uranium, and thorium.respect, uranium and thorium are niobium in carbonatitcs.

  3. Phonon dispersion in graphene

    E-Print Network [OSTI]

    L. A. Falkovsky


    Taking into account the constraints imposed by the lattice symmetry, the phonon dispersion is calculated for graphene with interactions between the first and second nearest neighbors in the framework of the Born-von Karman model. Analytical expressions are obtained for the out-of-plane (bending) modes determined only by two force constants as well as for the in-plane modes with four force constants. Values of the force constants are found in fitting to elastic constants and Raman frequencies observed in graphite.


    SciTech Connect (OSTI)

    Sanfilippo, Antonio P.; McGrath, Liam R.; Whitney, Paul D.


    We present a computational approach to radical rhetoric that leverages the co-expression of rhetoric and action features in discourse to identify violent intent. The approach combines text mining and machine learning techniques with insights from Frame Analysis and theories that explain the emergence of violence in terms of moral disengagement, the violation of sacred values and social isolation in order to build computational models that identify messages from terrorist sources and estimate their proximity to an attack. We discuss a specific application of this approach to a body of documents from and about radical and terrorist groups in the Middle East and present the results achieved.

  5. Consequentialism in Transition

    E-Print Network [OSTI]

    Coons, Christian


    the value of state transitions will allow us to sayConsequentialism in Transition Christian Coons Bowling Greenvalue of the state transitions, and not the states of

  6. Confusion in Thermodynamics

    E-Print Network [OSTI]

    Jeremy Dunning-Davies; David Sands


    For a long time now, confusion has existed in the minds of many over the meaning of various concepts in thermodynamics. Recently, this point has been brought to people's attention by two articles appearing on the well-known archive (arxiv) web site. The content of these two pieces serves to illustrate many of the problems and has occasioned the construction of this answer to at least some of them. The position of the axiom proposed by Carath\\'eodory is central in this matter and here its position is clarified and secured within the framework of thermodynamics. In particular, its relation to the First Law is examined and justified.

  7. Undergraduate Advisors in Mathematics

    E-Print Network [OSTI]

    Sample Plans of Study can be found in the information for mathematics majors on the Majors and Minor information page. Department of Mathematics, Purdue...

  8. Citizen science in archaeology

    E-Print Network [OSTI]

    Smith, ML


    Melinda A. Zeder Smith] CITIZEN SCIENCE IN ARCHAEOLOGY 2014and Application of Citizen Science. Biological ConservationHilchey 2011 A Review of Citizen Science and Community-Based

  9. Geothermal Prospects in Colorado

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

    Prospects in Colorado Geothermal Peer Review Bobi Garrett Deputy Laboratory Director Strategic Programs and Partnerships April 22, 2013 2 NREL Snapshot * Physical Assets Owned by...

  10. Essays in Public Economics

    E-Print Network [OSTI]

    Lee, Insook


    of what is so called the dot com bubble. First of all, Coiletriggered by the burst of dot com bubble in 2000, estimation

  11. Tungsten diffusion in silicon

    SciTech Connect (OSTI)

    De Luca, A.; Texier, M.; Burle, N.; Oison, V.; Pichaud, B. [Aix-Marseille Universit, IM2NP UMR 7334, Facult des Sciences et Techniques, Campus de Saint-Jrme, Avenue Escadrille Normandie Niemen - Case 142, F-13397 Marseille Cedex (France); Portavoce, A., E-mail: [CNRS, IM2NP UMR 7334, Facult des Sciences et Techniques, Campus de Saint-Jrme, Avenue Escadrille Normandie Niemen - Case 142, F-13397 Marseille Cedex (France); Grosjean, C. [STMicroelectronics, Rousset (France)


    Two doses (10{sup 13} and 10{sup 15}?cm{sup ?2}) of tungsten (W) atoms were implanted in different Si(001) wafers in order to study W diffusion in Si. The samples were annealed or oxidized at temperatures between 776 and 960?C. The diffusion profiles were measured by secondary ion mass spectrometry, and defect formation was studied by transmission electron microscopy and atom probe tomography. W is shown to reduce Si recrystallization after implantation and to exhibit, in the temperature range investigated, a solubility limit close to 0.15%0.2%, which is higher than the solubility limit of usual metallic impurities in Si. W diffusion exhibits unusual linear diffusion profiles with a maximum concentration always located at the Si surface, slower kinetics than other metals in Si, and promotes vacancy accumulation close to the Si surface, with the formation of hollow cavities in the case of the higher W dose. In addition, Si self-interstitial injection during oxidation is shown to promote W-Si clustering. Taking into account these observations, a diffusion model based on the simultaneous diffusion of interstitial W atoms and W-Si atomic pairs is proposed since usual models used to model diffusion of metallic impurities and dopants in Si cannot reproduce experimental observations.

  12. Spin waves in the (

    SciTech Connect (OSTI)

    Lipscombe, O. J. [University of Tennessee, Knoxville (UTK); Chen, G. F. [The Institute of Physics, Chinese Academy of Sciences; Fang, Chen [Purdue University; Perring, T. G. [ISIS Facility, Rutherford Appleton Laboratory; Abernathy, Douglas L [ORNL; Christianson, Andrew D [ORNL; Egami, Takeshi [ORNL; Wang, Nanlin [The Institute of Physics, Chinese Academy of Sciences; Hu, Jiangping [Purdue University and Chinese Academy of Sciences; Dai, Pengcheng [University of Tennessee, Knoxville (UTK)


    We use neutron scattering to show that spin waves in the iron chalcogenide Fe{sub 1.05}Te display novel dispersion clearly different from both the first principles density functional calculations and recent observations in the related iron pnictide CaFe{sub 2}As{sub 2}. By fitting to a Heisenberg Hamiltonian, we find that although the nearest-neighbor exchange couplings in the two systems are quite different, their next-nearest-neighbor (NNN) couplings are similar. This suggests that superconductivity in the pnictides and chalcogenides share a common magnetic origin that is intimately associated with the NNN magnetic coupling between the irons.

  13. Complementarity in the multiverse

    SciTech Connect (OSTI)

    Bousso, Raphael [Center for Theoretical Physics, Department of Physics University of California, Berkeley, California 94720-7300 (United States) and Lawrence Berkeley National Laboratory, Berkeley, California 94720-8162 (United States)


    In the multiverse, as in AdS space, light cones relate bulk points to boundary scales. This holographic UV-IR connection defines a preferred global time cutoff that regulates the divergences of eternal inflation. An entirely different cutoff, the causal patch, arises in the holographic description of black holes. Remarkably, I find evidence that these two regulators define the same probability measure in the multiverse. Initial conditions for the causal patch are controlled by the late-time attractor regime of the global description.

  14. Complementarity in the Multiverse

    E-Print Network [OSTI]

    Raphael Bousso


    In the multiverse, as in AdS, light-cones relate bulk points to boundary scales. This holographic UV-IR connection defines a preferred global time cut-off that regulates the divergences of eternal inflation. An entirely different cut-off, the causal patch, arises in the holographic description of black holes. Remarkably, I find evidence that these two regulators define the same probability measure in the multiverse. Initial conditions for the causal patch are controlled by the late-time attractor regime of the global description.

  15. Essays in Environmental Economics

    E-Print Network [OSTI]

    Foreman, Kathleen


    vineyards due to these water shortages (DWR, 2012). Whilecosts of irrigation water shortages. Bibliography [1] Alexto a severe shortage of surface irrigation water. In one of

  16. Insurgency in Academic Publishing

    E-Print Network [OSTI]

    Miller, Ruth


    read, and share academic articles. Gowers argued thatresearch. Academic journals, like the BPJ, solicit articles,s article found ample kindling in the academic community

  17. Scattering in an environment

    E-Print Network [OSTI]

    Janos Polonyi; Karima Zazoua


    The cross section of elastic electron-proton scattering taking place in an electron gas is calculated within the Closed Time Path method. It is found to be the sum of two terms, one being the expression in the vacuum except that it involves dressing due to the electron gas. The other term is due to the scattering particles-electron gas entanglement. This term dominates the usual one when the exchange energy is in the vicinity of the Fermi energy. Furthermore it makes the trajectories of the colliding particles more consistent and the collision more irreversible, rendering the scattering more classical in this regime.

  18. Farmland Reforestation in China

    E-Print Network [OSTI]

    Kelly, Peter Alfred


    2. Questionnaire design and survey management The surveyof Economics and Management, for making the survey possible,of the survey were conducted in accordance with management

  19. Flexibility in Testing Configurations

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

    Technologies Laboratory and the National Solar Thermal Test Facility to advance the reliability, interconnectivity, and availability of solar technologies in the nation's...

  20. in the Sciences Mathematics

    E-Print Network [OSTI] APPLICATIONS should be submitted by May 31, 2014, at Nihat Ay MPI for Mathematics in the Sciences Marc

  1. What's In My Water?

    E-Print Network [OSTI]

    Provin, Tony; Pitt, John L.


    .The salts in conductivity levels are conductivity levels. allow for too much water to evaporate water are not just table high, evaluate other from the surface, or where soils are salt, but are often a individual characteristics naturally high in salts...- tive safety margin. You can have your water analyzed by a government agency or a private company. 13 Salt: an organic or inorganic com- pound that is subject to dissociation when water is added, resulting in a dis- tinct increase in specific anions...

  2. Plasmons in strong superconductors

    E-Print Network [OSTI]

    Marcello Baldo; Camille Ducoin


    We present a study of the possible plasmon excitations that can occur in systems where strong superconductivity is present. In these systems the plasmon energy is comparable to, or smaller than the pairing gap. As a prototype of these systems we consider the proton component of neutron star matter just below the crust when electron screening is not taken into account. For the realistic case we consider in detail the different aspects of the elementary excitations when the proton, electron components are considered within the Random Phase Approximation generalized to the superfluid case, while the influence of the neutron component is considered only at qualitative level. Electron screening plays a major role in modifying the proton spectrum and spectral function. At the same time the electron plasmon is strongly modified and damped by the indirect coupling with the superfluid proton component, even at moderately low values of the gap. The excitation spectrum shows the interplay of the different components and their relevance for each excitation mode. The results are relevant for neutrino physics and thermodynamical processes in neutron stars. If electron screening is neglected, the spectral properties of the proton component show some resemblance with the physical situation in high T$_c$ superconductors, and we briefly discuss similarities and differences in this connection. In a general prospect, the results of the study emphasize the role of Coulomb interaction in strong superconductors.

  3. Physical Vacuum in Superconductors

    E-Print Network [OSTI]

    Clovis Jacinto de Matos


    Although experiments carried out by Jain et al. showed that the Cooper pairs obey the strong equivalence principle, The measurement of the Cooper pairs inertial mass by Tate et al. revealed an anomalous excess of mass. In the present paper we interpret these experimental results in the framework of an electromagnetic model of dark energy for the superconductors' vacuum. We argue that this physical vacuum is associated with a preferred frame. Ultimately from the conservation of energy for Cooper pairs we derive a model for a variable vacuum speed of light in the superconductors physical vacuum in relation with a possible breaking of the weak equivalence principle for Cooper pairs.

  4. Dynamic Chirality in Nuclei

    SciTech Connect (OSTI)

    Tonev, D. [Institute for Nuclear Research and Nuclear Energy, BAS, 1784 Sofia (Bulgaria); INFN, Laboratori Nazionali di Legnaro, 35020 Legnaro (Italy); Angelis, G. de [INFN, Laboratori Nazionali di Legnaro, 35020 Legnaro (Italy); Brant, S. [Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Petkov, P. [Institute for Nuclear Research and Nuclear Energy, BAS, 1784 Sofia (Bulgaria); Ventura, A. [ENEA, 40129 Bologna and INFN, Sezione di Bologna (Italy)


    The possible chiral interpretation of twin bands in odd-odd nuclei was investigated in the Interacting Boson Fermion-Fermion Model. The analysis of the wave functions has shown that the possibility for angular momenta of the valence proton, neutron and core to find themselves in the favorable, almost orthogonal geometry is present, but not dominant. Such behaviour is found to be similar in nuclei where both the level energies and the electromagnetic decay properties display the chiral pattern, as well as in those where only the energies of the corresponding levels in the twin bands are close together. The difference in the structure of the two types of chiral candidates nuclei can be attributed to different beta and gamma fluctuations, induced by the exchange boson-fermion interaction of the Interacting Boson Fermion-Fermion Model. In both cases the chirality is weak and dynamic. The existence of doublets of bands in {sup 134}Pr can be attributed to dynamic chirality dominated by shape fluctuations.

  5. In Other News

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn Other News Community Connections: Your link to news andInInIn

  6. In other news

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn Other News Community Connections: Your link toinaIn otherInIn

  7. In other news

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn Other News Community Connections: Your link toinaInIn otherIn

  8. In other news

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn Other News Community Connections: Your link toinaInInIn other

  9. In other news

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn Other News Community Connections: Your link toinaInInIn

  10. In other news

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn Other News Community Connections: Your linkIn other newsInIn

  11. In other news

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn Other News Community Connections: Your linkIn otherIn otherIn

  12. Nurturing Connections Among Women in Technology in India | GE...

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

    Nurturing Connections Among Women in Technology in India Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click to share (Opens in new...

  13. Misadventures in Conservation and Development

    E-Print Network [OSTI]

    Hall, Sharon J.

    and Development Projects in Indonesian national parks, the global trade in electronic waste, and the regulation

  14. in Condensed Matter Physics

    E-Print Network [OSTI]

    van der Torre, Leon

    Master in Condensed Matter Physics Master acadmique #12;2 #12;3 Students at the University. Condensed matter physics is about explaining and predicting the relationship between the atomic, and broad education in the field of condensed matter physics introduce you to current research topics

  15. Concentration in Green Design

    E-Print Network [OSTI]

    Shewchuk, Jonathan

    , energy, infrastructure or transport. Participants in this specialization area work closely with the GreenConcentration in Green Design Research and Education Opportunities Carnegie Mellon University Civil and Environmental Engineering M.S. Concentration Green Design - Course Only Track As an extension


    E-Print Network [OSTI]

    Shemer, Lev

    frequency harmonics arrive at the focusing location in phase, a very steep wave single emerges evolution; Bound (locked) waves 1. Introduction Generation of very steep waves in wave tanks enables experimental study of the wave damage potential and is thus of great importance. Excitation of a single steep


    E-Print Network [OSTI]

    Leistikow, Bruce N.

    -Response and Estimating Equa- tions, Mixed and Random Effects Modeling, and the Analysis of Molecular Sequence Data are researchers with widely varying back- grounds, espousing a wide variety of methodological approaches. #12;4 The program in Biostatistics provides students with: Solid training in the biostatistical core disciplines

  18. Silica in Protoplanetary Disks

    E-Print Network [OSTI]

    B. A. Sargent; W. J. Forrest; C. Tayrien; M. K. McClure; A. Li; A. R. Basu; P. Manoj; D. M. Watson; C. J. Bohac; E. Furlan; K. H. Kim; J. D. Green; G. C. Sloan


    Mid-infrared spectra of a few T Tauri stars (TTS) taken with the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope show prominent narrow emission features indicating silica (crystalline silicon dioxide). Silica is not a major constituent of the interstellar medium; therefore, any silica present in the circumstellar protoplanetary disks of TTS must be largely the result of processing of primitive dust material in the disks surrouding these stars. We model the silica emission features in our spectra using the opacities of various polymorphs of silica and their amorphous versions computed from earth-based laboratory measurements. This modeling indicates that the two polymorphs of silica, tridymite and cristobalite, which form at successively higher temperatures and low pressures, are the dominant forms of silica in the TTS of our sample. These high temperature, low pressure polymorphs of silica present in protoplanetary disks are consistent with a grain composed mostly of tridymite named Ada found in the cometary dust samples collected from the STARDUST mission to Comet 81P/Wild 2. The silica in these protoplanetary disks may arise from incongruent melting of enstatite or from incongruent melting of amorphous pyroxene, the latter being analogous to the former. The high temperatures of 1200K-1300K and rapid cooling required to crystallize tridymite or cristobalite set constraints on the mechanisms that could have formed the silica in these protoplanetary disks, suggestive of processing of these grains during the transient heating events hypothesized to create chondrules.

  19. LCLS Laser (in Polish)

    E-Print Network [OSTI]

    Romaniuk, R S


    The most powerful now in the world, American X-ray laser LCLS (Linac Coherent Light Source), has been working as a research and user facility since 2009. It is further developed to LCLSII machine at the Stanford National Accelerator Laboratory SLAC in Menlo Park CA. In a certain sense, LCLS is a response to the EXFEL machine and a logical extension of LCLS. All these machines are light sources of the fifth generation. EXFELis expected to open user facility in 2016, at a cost of over 1 bil Euro. LCLS II, which design started in 2010, will be operational in 2017. The lasers LCLS, LCLS II and EXFEL use SASE and SEED methods to generate light and are powered by electron liniacs, LCLS by a wrm one, and EXFEL by a cold one. The liniacs have energies approaching 20 GeV, and are around 2 - 3 km in length. EXFEL liniac uses SRF TESLA cavity technology at 1,3GHz. A prototype of EXFEL was FLASH laser. SLAC Laboratory uses effectively over 50 years experience in research, building and exploitation of linear electron acce...

  20. Renewable Energy in Alaska

    SciTech Connect (OSTI)

    Not Available


    This report examines the opportunities, challenges, and costs associated with renewable energy implementation in Alaska and provides strategies that position Alaska's accumulating knowledge in renewable energy development for export to the rapidly growing energy/electric markets of the developing world.

  1. Mechanisms in Plant Development

    SciTech Connect (OSTI)

    Hake, Sarah [USDA ARS Plant Gene Expression Center


    This meeting has been held every other year for the past twenty-two years and is the only regularly held meeting focused specifically on plant development. Topics covered included: patterning in developing tissues; short and long distance signaling; differentiation of cell types; the role of epigenetics in development; evolution; growth.

  2. International Programs in Agriculture

    E-Print Network [OSTI]

    International Programs in Agriculture MessagefromtheDirector Staying Ahead of Globalization and more prosperous place for all. Fortunately, Purdue International Programs in Agriculture (IPIA) has natural disasters caution us to remember the power of nature. The United Nations Food and Agriculture

  3. in this issue Visualising

    E-Print Network [OSTI]

    Fernandez, Thomas

    in this issue Visualising Evolutionary Search Spaces James McDermott Unshackling Evolution Nick just published new Master or PhD theses, if you want to let our community know how your workshop) that you wish to advertise, just drop me an email. In this issue we have a new article by James Mc

  4. Environmental gentrification in Berlin

    E-Print Network [OSTI]

    Schroder, Nina

    In an age of rising global environmental concerns, cities have come to play a key role in managing environmental issues such as climate change and food security on more regional and local scales and thus have become the locus for sustainable...

  5. Sustainability in colleges 15

    E-Print Network [OSTI]

    Melham, Tom

    Sustainability in colleges 15 Carbon reduction 5 Water 7 Travel8 Waste,recyclingandreuse10 Sustainability Report 2011/2012 #12;2University of Oxford Environmental Sustainability Report 2011/12 "As Chair of the Sustainability Steering Group, I have seen a significant shift in staff and students' expectations

  6. Proceedings in MANUFACTURING

    E-Print Network [OSTI]

    Paris-Sud XI, Universit de

    . EXPERIMENTAL CHARACTERIZATION OF ROBOT ARM RIGIDITY IN ORDER TO BE USED IN MACHINING OPERATION Jean-Yves K at the end of a robot arm poly-articulated date back twenty years, but these robots were not designed configuration of the robot arm on the overall stiffness of the system. The spindle is taken into account

  7. Polyhydroxyalkanoate synthesis in plants

    DOE Patents [OSTI]

    Srienc, Friedrich (Lake Elmo, MN); Somers, David A. (Roseville, MN); Hahn, J. J. (New Brighton, MN); Eschenlauer, Arthur C. (Circle Pines, MN)


    Novel transgenic plants and plant cells are capable of biosynthesis of polyhydroxyalkanoate (PHA). Heterologous enzymes involved in PHA biosynthesis, particularly PHA polymerase, are targeted to the peroxisome of a transgenic plant. Transgenic plant materials that biosynthesize short chain length monomer PHAs in the absence of heterologous .beta.-ketothiolase and acetoacetyl-CoA reductase are also disclosed.

  8. Caching in wireless networks

    E-Print Network [OSTI]

    Niesen, Urs

    We consider the problem of delivering content cached in a wireless network of n nodes randomly located on a square of area n. In the most general form, this can be analyzed by considering the 2[superscript n] timesn-dimensional ...

  9. Genetics in the courts

    SciTech Connect (OSTI)

    Coyle, Heather; Drell, Dan


    Various: (1)TriState 2000 Genetics in the Courts (2) Growing impact of the new genetics on the courts (3)Human testing (4) Legal analysis - in re G.C. (5) Legal analysis - GM ''peanots'', and (6) Legal analysis for State vs Miller

  10. Innovation in Computer Sciences

    E-Print Network [OSTI]

    Ghosh, Joydeep

    power- up Innovation in Computer Sciences Department of Computer Sciences at The University of Texas at Austin #12;#12;Computer science is the enabling science of our age. It is the engine. In the Department of Computer Sciences at The University of Texas at Austin, one of the top ten departments

  11. Geothermal energy in Nevada

    SciTech Connect (OSTI)

    Not Available


    The nature of goethermal resources in Nevada and resource applications are discussed. The social and economic advantages of utilizing geothermal energy are outlined. Federal and State programs established to foster the development of geothermal energy are discussed. The names, addresses, and phone numbers of various organizations actively involved in research, regulation, and the development of geothermal energy are included. (MHR)

  12. Progress in colloid propulsion

    E-Print Network [OSTI]

    Lpez Urdiales, Jse Mariano, 1977-


    In the early decades of the Space Age, a great deal of work was put into the development of the Colloid Thruster as an electric propulsion system for spacecraft. In spite of the effort by the end of the 70s the programs ...

  13. High Performance Computing in

    E-Print Network [OSTI]

    Stamatakis, Alexandros

    High Performance Computing in Bioinformatics Thomas Ludwig ( Ruprecht PART I: High Performance Computing Thomas Ludwig PART II: HPC Computing in Bioinformatics Alexandros #12; Thomas Ludwig, Alexandros Stamatakis, GCB'04 3 PART I High Performance Computing Introduction

  14. ARTICLE IN PRESS Automatica ( )

    E-Print Network [OSTI]

    ARTICLE IN PRESS Automatica ( ) Contents lists available at ScienceDirect Automatica journal parameter, the regularization constant which is used to trade-off fit and the number of segments. 2010 or equals the number of observations we would get a perfect fit, at the price of models that adjust in every

  15. Engineering in Process Metallurgy

    E-Print Network [OSTI]

    New South Wales, University of

    MATS3003 Engineering in Process Metallurgy Course Outline Session 1, 2014 School of Materials ................................................................................................... 7 Course Objective To introduce the basic operations in process metallurgy and to provide Course at a Glance What you will learn Weeks Assessment Task Introduction - What is process metallurgy

  16. Parastillation Process in Operations

    E-Print Network [OSTI]

    Canfield, F.; Jenkins, O.


    The Parastillation process is a new method for multi-stage, counter-current contact between vapor and liquid that results in 33% more ideal stages than distillation for a given tray spacing. Patents have been granted in the U.S.A., U.K., Europe...

  17. Topics in Quantum Dynamics

    E-Print Network [OSTI]

    A. Jadczyk


    The paper consists of two parts. In the first part Schroedinger's equation for a charged quantum particle in a Galilei-Newton curved space-time is derived in a fully geometrical way. Gravitational and electromagnetic fields are coded into space metric and space-time connection. The fundamental geometrical object is a quantum connection in a Hermitian line bundle over the 7-dimensional jet space of 3-velocities. The secondary object is the bundle of Hilbert spaces over absolute time. Time appears as a superselection quantity while Shroedinger equation is interpreted as parallel transport in this bundle. In the second part the problem of measurement in quantum theory is discussed as a part of a more general problem of coupling between quantum and classical systems. The standard framework of quantum theory is extended so as to allow for dynamical central observables within dissipative dynamics. It is shown that within this approach one obtains not only Liouville equation that describes statistical ensembles, but also a piecewise-deterministic random process describing sequences of "events" that can be monitored by a continuous observation of the single, coupled classical system. It also describes "quantum jumps" or "wave packet reductions" that accompany these events. Two example are worked out in some details. The last one deals with the problem oof "how to determine the wave function ?".

  18. Fire in Buildings

    E-Print Network [OSTI]

    Shorter, G.

    During the lifetime of any building in Canada it is probable that one or more "unwanted" fires will occur. "Fire Loss in Canada, 1959," the report of the Dominion Fire Commissioner, states that for the period 1950-1959 the average number of reported...

  19. Introduction Transport in disordered graphene

    E-Print Network [OSTI]

    Fominov, Yakov

    Introduction Transport in disordered graphene Summary Ballistic transport in disordered graphene P, Gornyi, Mirlin Ballistic transport in disordered graphene #12;Introduction Transport in disordered graphene Summary Outline 1 Introduction Model Experimental motivation Transport in clean graphene 2

  20. Effective contracts in supply chains

    E-Print Network [OSTI]

    Shum, Wanhang


    In the past decade, we have seen significant increase in the level of outsourcing in many industries. This increase in the level of outsourcing increases the importance of implementing effective contracts in supply chains. ...

  1. Tabled Execution in Scheme

    SciTech Connect (OSTI)

    Willcock, J J; Lumsdaine, A; Quinlan, D J


    Tabled execution is a generalization of memorization developed by the logic programming community. It not only saves results from tabled predicates, but also stores the set of currently active calls to them; tabled execution can thus provide meaningful semantics for programs that seemingly contain infinite recursions with the same arguments. In logic programming, tabled execution is used for many purposes, both for improving the efficiency of programs, and making tasks simpler and more direct to express than with normal logic programs. However, tabled execution is only infrequently applied in mainstream functional languages such as Scheme. We demonstrate an elegant implementation of tabled execution in Scheme, using a mix of continuation-passing style and mutable data. We also show the use of tabled execution in Scheme for a problem in formal language and automata theory, demonstrating that tabled execution can be a valuable tool for Scheme users.

  2. Perturbations in a plasma

    E-Print Network [OSTI]

    Evangelos Chaliasos


    The perturbations of a homogeneous non-relativistic two-component plasma are studied in the Coulomb gauge. Starting from the solution found [2] of the equations of electromagnetic self consistency in a plasma [1], we add small perturbations to all quantities involved, and we enter the perturbed quantities in the equations, keeping only the first order terms in the perturbations. Because the unperturbed quantities are solutions of the equations, they cancel each other, and we are left with a set of 12 linear equations for the 12 perturbations (unknown quantities). Then we solve this set of linearized equations, in the approximation of small ratio of the masses of electrons over those of ions, and under the assumption that the plasma remains homogeneous.

  3. Strangeness in Neutron Stars

    E-Print Network [OSTI]

    Fridolin Weber; Alexander Ho; Rodrigo P. Negreiros; Philip Rosenfield


    It is generally agreed on that the tremendous densities reached in the centers of neutron stars provide a high-pressure environment in which several intriguing particles processes may compete with each other. These range from the generation of hyperons to quark deconfinement to the formation of kaon condensates and H-matter. There are theoretical suggestions of even more exotic processes inside neutron stars, such as the formation of absolutely stable strange quark matter. In the latter event, neutron stars would be largely composed of strange quark matter possibly enveloped in a thin nuclear crust. This paper gives a brief overview of these striking physical possibilities with an emphasis on the role played by strangeness in neutron star matter, which constitutes compressed baryonic matter at ultra-high baryon number density but low temperature which is no accessible to relativistic heavy ion collision experiments.

  4. Uncertainties in Gapped Graphene

    E-Print Network [OSTI]

    Eylee Jung; Kwang S. Kim; DaeKil Park


    Motivated by graphene-based quantum computer we examine the time-dependence of the position-momentum and position-velocity uncertainties in the monolayer gapped graphene. The effect of the energy gap to the uncertainties is shown to appear via the Compton-like wavelength $\\lambda_c$. The uncertainties in the graphene are mainly contributed by two phenomena, spreading and zitterbewegung. While the former determines the uncertainties in the long-range of time, the latter gives the highly oscillation to the uncertainties in the short-range of time. The uncertainties in the graphene are compared with the corresponding values for the usual free Hamiltonian $\\hat{H}_{free} = (p_1^2 + p_2^2) / 2 M$. It is shown that the uncertainties can be under control within the quantum mechanical law if one can choose the gap parameter $\\lambda_c$ freely.

  5. Conditional sterility in plants

    DOE Patents [OSTI]

    Meagher, Richard B. (Athens, GA); McKinney, Elizabeth (Athens, GA); Kim, Tehryung (Taejeon, KR)


    The present disclosure provides methods, recombinant DNA molecules, recombinant host cells containing the DNA molecules, and transgenic plant cells, plant tissue and plants which contain and express at least one antisense or interference RNA specific for a thiamine biosynthetic coding sequence or a thiamine binding protein or a thiamine-degrading protein, wherein the RNA or thiamine binding protein is expressed under the regulatory control of a transcription regulatory sequence which directs expression in male and/or female reproductive tissue. These transgenic plants are conditionally sterile; i.e., they are fertile only in the presence of exogenous thiamine. Such plants are especially appropriate for use in the seed industry or in the environment, for example, for use in revegetation of contaminated soils or phytoremediation, especially when those transgenic plants also contain and express one or more chimeric genes which confer resistance to contaminants.

  6. Irradiation Creep in Graphite

    SciTech Connect (OSTI)

    Ubic, Rick; Butt, Darryl; Windes, William


    An understanding of the underlying mechanisms of irradiation creep in graphite material is required to correctly interpret experimental data, explain micromechanical modeling results, and predict whole-core behavior. This project will focus on experimental microscopic data to demonstrate the mechanism of irradiation creep. High-resolution transmission electron microscopy should be able to image both the dislocations in graphite and the irradiation-induced interstitial clusters that pin those dislocations. The team will first prepare and characterize nanoscale samples of virgin nuclear graphite in a transmission electron microscope. Additional samples will be irradiated to varying degrees at the Advanced Test Reactor (ATR) facility and similarly characterized. Researchers will record microstructures and crystal defects and suggest a mechanism for irradiation creep based on the results. In addition, the purchase of a tensile holder for a transmission electron microscope will allow, for the first time, in situ observation of creep behavior on the microstructure and crystallographic defects.

  7. PCBs found in PILC

    SciTech Connect (OSTI)

    Lauterback, S.


    A number of utilities have discovered polychlorinated biphenyls (PCBs) in paper-insulated, lead-covered cable (PILIC) systems. The extent of this problem is of such concern that it is included in the regulatory revisions currently being proposed by the US Environmental Protection Agency (EPA). The vast number of these systems, together with results form our studies virtually assures the widespread presence of PCBs in underground systems. The dual hazards associated with exposure of lead to humans and acceptance of the presence of PCBs in cable is forcing companies to develop sophisticated testing and new maintenance procedures. Age old disposal practices suspected of contaminating scarp yards and exposing workers to lead poisoning will be phased out in favor of controlled, indoor operations developed specifically for the safe disposal of this material.

  8. Axions in String Theory

    SciTech Connect (OSTI)

    Svrcek, Peter; /Stanford U., Phys. Dept. /SLAC; Witten, Edward; /Princeton, Inst. Advanced Study


    In the context of string theory, axions appear to provide the most plausible solution of the strong CP problem. However, as has been known for a long time, in many string-based models, the axion coupling parameter Fa is several orders of magnitude higher than the standard cosmological bounds. We re-examine this problem in a variety of models, showing that Fa is close to the GUT scale or above in many models that have GUT-like phenomenology, as well as some that do not. On the other hand, in some models with Standard Model gauge fields supported on vanishing cycles, it is possible for Fa to be well below the GUT scale.

  9. Measuring Value in Healthcare

    E-Print Network [OSTI]

    Gardner, Christopher


    A statistical description and model of individual healthcare expenditures in the US has been developed for measuring value in healthcare. We find evidence that healthcare expenditures are quantifiable as an infusion-diffusion process, which can be thought of intuitively as a steady change in the intensity of treatment superimposed on a random process reflecting variations in the efficiency and effectiveness of treatment. The arithmetic mean represents the net average annual cost of healthcare; and when multiplied by the arithmetic standard deviation, which represents the effective risk, the result is a measure of healthcare cost control. Policymakers, providers, payors, or patients that decrease these parameters are generating value in healthcare. The model has an average absolute prediction error of approximately 10-12% across the range of expenditures which spans 6 orders of magnitude over a nearly 10-year period. For the top 1% of the population with the largest expenditures, representing 20%-30% of total ...

  10. Coal in China

    SciTech Connect (OSTI)

    Minchener, A.J. [IEA Clean Coal Centre, London (United Kingdom)


    The article gives an overview of the production and use of coal in China, for power generation and in other sectors. Coal use for power generation was 850 million tonnes in 2003 and 800 million tonnes in the non-power sector. The majority of power will continue to be produced from coal, with a trend towards new larger pulverised coal fired units and introduction of circulating fluidised bed combustors. Stricter regulations are forcing introduction of improved pollution control technologies. It seems likely that China will need international finance to supplement private and state investment to carry out a programme to develop and apply clean coal technologies. The author concludes that there is evidence of a market economy being established but there is a need to resolve inconsistencies with the planned aspects of the economy and that additional policies are needed in certain sectors to achieve sustainable development. 1 ref., 2 figs., 2 tabs.

  11. Strains in General Relativity

    E-Print Network [OSTI]

    Donato Bini; Fernando de Felice; Andrea Geralico


    The definition of relative accelerations and strains among a set of comoving particles is studied in connection with the geometric properties of the frame adapted to a "fiducial observer." We find that a relativistically complete and correct definition of strains must take into account the transport law of the chosen spatial triad along the observer's congruence. We use special congruences of (accelerated) test particles in some familiar spacetimes to elucidate such a point. The celebrated idea of Szekeres' compass of inertia, arising when studying geodesic deviation among a set of free-falling particles, is here generalized to the case of accelerated particles. In doing so we have naturally contributed to the theory of relativistic gravity gradiometer. Moreover, our analysis was made in an observer-dependent form, a fact that would be very useful when thinking about general relativistic tests on space stations orbiting compact objects like black holes and also in other interesting gravitational situations.

  12. Energy balance in peridynamics.

    SciTech Connect (OSTI)

    Lehoucq, Richard B.; Silling, Stewart Andrew


    The peridynamic model of solid mechanics treats internal forces within a continuum through interactions across finite distances. These forces are determined through a constitutive model that, in the case of an elastic material, permits the strain energy density at a point to depend on the collective deformation of all the material within some finite distance of it. The forces between points are evaluated from the Frechet derivative of this strain energy density with respect to the deformation map. The resulting equation of motion is an integro-differential equation written in terms of these interparticle forces, rather than the traditional stress tensor field. Recent work on peridynamics has elucidated the energy balance in the presence of these long-range forces. We have derived the appropriate analogue of stress power, called absorbed power, that leads to a satisfactory definition of internal energy. This internal energy is additive, allowing us to meaningfully define an internal energy density field in the body. An expression for the local first law of thermodynamics within peridynamics combines this mechanical component, the absorbed power, with heat transport. The global statement of the energy balance over a subregion can be expressed in a form in which the mechanical and thermal terms contain only interactions between the interior of the subregion and the exterior, in a form anticipated by Noll in 1955. The local form of this first law within peridynamics, coupled with the second law as expressed in the Clausius-Duhem inequality, is amenable to the Coleman-Noll procedure for deriving restrictions on the constitutive model for thermomechanical response. Using an idea suggested by Fried in the context of systems of discrete particles, this procedure leads to a dissipation inequality for peridynamics that has a surprising form. It also leads to a thermodynamically consistent way to treat damage within the theory, shedding light on how damage, including the nucleation and advance of cracks, should be incorporated into a constitutive model.

  13. Aberration in gravitational lensing

    SciTech Connect (OSTI)

    Sereno, M. [Institut fuer Theoretische Physik, Universitaet Zuerich, Winterthurerstrasse 190, CH-8057 Zuerich (Switzerland)


    It is known that a relative translational motion between the deflector and the observer affects gravitational lensing. In this paper, a lens equation is obtained to describe such effects on actual lensing observables. Results can be easily interpreted in terms of aberration of light rays. Both radial and transverse motions with relativistic velocities are considered. The lens equation is derived by first considering geodesic motion of photons in the rest-frame Schwarzschild space-time of the lens, and, then, light-ray detection in the moving observer's frame. Because of the transverse motion images are displaced and distorted in the observer's celestial sphere, whereas the radial velocity along the line of sight causes an effective rescaling of the lens mass. The Einstein ring is distorted to an ellipse whereas the caustics in the source plane are still pointlike. Either for null transverse motion or up to linear order in velocities, the critical curve is still a circle with its radius corrected by a factor (1+z{sub d}) with respect to the static case, z{sub d} being the relativistic Doppler shift of the deflector. From the observational point of view, the orbital motion of the Earth can cause potentially observable corrections of the order of the {mu}arcsec in lensing towards the supermassive black hole at the Galactic center. On a cosmological scale, tangential peculiar velocities of a cluster of galaxies bring about a typical flexion in images of background galaxies in the weak lensing regime but future measurements seem to be too challenging.

  14. Coarsening in granular systems

    E-Print Network [OSTI]

    Andrea Baldassarri; Andrea Puglisi; Alessandro Sarracino


    We review a few representative examples of granular experiments or models where phase separation, accompanied by domain coarsening, is a relevant phenomenon. We first elucidate the intrinsic non-equilibrium, or athermal, nature of granular media. Thereafter, dilute systems, the so-called "granular gases" are discussed: idealized kinetic models, such as the gas of inelastic hard spheres in the cooling regime, are the optimal playground to study the slow growth of correlated structures, e.g. shear patterns, vortices and clusters. In fluidized experiments, liquid-gas or solid-gas separations have been observed. In the case of monolayers of particles, phase coexistence and coarsening appear in several different setups, with mechanical or electrostatic energy input. Phenomenological models describe, even quantitatively, several experimental measures, both for the coarsening dynamics and for the dynamic transition between different granular phases. The origin of the underlying bistability is in general related to negative compressibility from granular hydrodynamics computations, even if the understanding of the mechanism is far from complete. A relevant problem, with important industrial applications, is related to the demixing or segregation of mixtures, for instance in rotating tumblers or on horizontally vibrated plates. Finally, the problem of compaction of highly dense granular materials, which has many important applications, is usually described in terms of coarsening dynamics: there, bubbles of mis-aligned grains evaporate, allowing the coalescence of optimally arranged islands and a progressive reduction of total occupied volume.

  15. Transition temperature in QCD

    SciTech Connect (OSTI)

    Cheng, M.; Christ, N. H.; Mawhinney, R. D. [Physics Department, Columbia University, New York, New York 10027 (United States); Datta, S.; Jung, C.; Schmidt, C.; Umeda, T. [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Heide, J. van der; Kaczmarek, O.; Laermann, E.; Miao, C. [Fakultaet fuer Physik, Universitaet Bielefeld, D-33615 Bielefeld (Germany); Karsch, F. [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Fakultaet fuer Physik, Universitaet Bielefeld, D-33615 Bielefeld (Germany); Petreczky, P. [Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, New York 11973 (United States); Petrov, K. [Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen (Denmark)


    We present a detailed calculation of the transition temperature in QCD with two light and one heavier (strange) quark mass on lattices with temporal extent N{sub {tau}}=4 and 6. Calculations with improved staggered fermions have been performed for various light to strange quark mass ratios in the range, 0.05{<=}m-circumflex{sub l}/m-circumflex{sub s}{<=}0.5, and with a strange quark mass fixed close to its physical value. From a combined extrapolation to the chiral (m-circumflex{sub l}{yields}0) and continuum (aT{identical_to}1/N{sub {tau}}{yields}0) limits we find for the transition temperature at the physical point T{sub c}r{sub 0}=0.457(7) where the scale is set by the Sommer-scale parameter r{sub 0} defined as the distance in the static quark potential at which the slope takes on the value (dV{sub qq}(r)/dr){sub r=r{sub 0}}=1.65/r{sub 0}{sup 2}. Using the currently best known value for r{sub 0} this translates to a transition temperature T{sub c}=192(7)(4) MeV. The transition temperature in the chiral limit is about 3% smaller. We discuss current ambiguities in the determination of T{sub c} in physical units and also comment on the universal scaling behavior of thermodynamic quantities in the chiral limit.


    SciTech Connect (OSTI)

    D.M. Jolley


    As directed by a written development plan (CRWMS M&O 1999a), a conceptual model for steel and corrosion products in the engineered barrier system (EBS) is to be developed. The purpose of this conceptual model is to assist Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE) Revision 2 (NRC 1999). This document provides the conceptual framework for the in-drift corrosion products sub-model to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. This model has been developed to serve as a basis for the in-drift geochemical analyses performed by PAO. However, the concepts discussed within this report may also apply to some near and far-field geochemical processes and may have conceptual application within the unsaturated zone (UZ) and saturated zone (SZ) transport modeling efforts.

  17. Benford distributions in NMR

    E-Print Network [OSTI]

    Gaurav Bhole; Abhishek Shukla; T. S. Mahesh


    Benford's Law is an empirical law which predicts the frequency of significant digits in databases corresponding to various phenomena, natural or artificial. Although counter intuitive at the first sight, it predicts a higher occurrence of digit 1, and decreasing occurrences to other larger digits. Here we report the Benford analysis of various NMR databases and draw several interesting inferences. We observe that, in general, NMR signals follow Benford distribution in time-domain as well as in frequency domain. Our survey included NMR signals of various nuclear species in a wide variety of molecules in different phases, namely liquid, liquid-crystalline, and solid. We also studied the dependence of Benford distribution on NMR parameters such as signal to noise ratio, number of scans, pulse angles, and apodization. In this process we also find that, under certain circumstances, the Benford analysis can distinguish a genuine spectrum from a visually identical simulated spectrum. Further we find that chemical-shift databases and amplitudes of certain radio frequency pulses generated using optimal control techniques also satisfy Benford's law to a good extent.

  18. Strangeness in Neutron Stars

    E-Print Network [OSTI]

    Fridolin Weber


    It is generally agreed on that the tremendous densities reached in the centers of neutron stars provide a high-pressure environment in which numerous novel particles processes are likely to compete with each other. These processes range from the generation of hyperons to quark deconfinement to the formation of kaon condensates and H-matter. There are theoretical suggestions of even more exotic processes inside neutron stars, such as the formation of absolutely stable strange quark matter, a configuration of matter even more stable than the most stable atomic nucleus, iron. In the latter event, neutron stars would be largely composed of pure quark matter, eventually enveloped in a thin nuclear crust. No matter which physical processes are actually realized inside neutron stars, each one leads to fingerprints, some more pronounced than others though, in the observable stellar quantities. This feature combined with the unprecedented progress in observational astronomy, which allows us to see vistas with remarkable clarity that previously were only imagined, renders neutron stars to nearly ideal probes for a wide range of physical studies, including the role of strangeness in dense matter.

  19. Pairing forces in nuclei

    SciTech Connect (OSTI)

    Chasman, R.R. [Argonne National Lab., IL (United States). Physics Div.


    In this contribution, the author mentions some features of pairing forces that are unique to nuclei and cover some areas of major interest in nuclear structure research, that involve pairing. At the level of most nuclear structure studies, nuclei are treated as consisting of two kinds of fermions (protons and neutrons) in a valence space with rather few levels. These features give rise to unique aspects of pairing forces in nuclei: (1) n-p pairing in T = 0 as well as the usual T = 1 pairing that is characteristic of like fermions; (2) a need to correct pairing calculations for the (1/N) effects that can typically be neglected in superconducting solids. An issue of current concern is the nature of the pairing interaction: several recent studies suggest a need for a density dependent form of the pairing interaction. There is a good deal of feedback between the questions of accurate calculations of pairing interactions and the form and magnitude of the pairing interaction. Finally, the authors discuss some many-body wave functions that are a generalization of the BCS wave function form, and apply them to a calculation of energy level spacings in superdeformed rotational bands.

  20. Branes in Supergroups

    E-Print Network [OSTI]

    Thomas Creutzig


    In this thesis we initiate a systematic study of branes in Wess-Zumino-Novikov-Witten models with Lie supergroup target space. We start by showing that a branes' worldvolume is a twisted superconjugacy class and construct the action of the boundary WZNW model. Then we consider symplectic fermions and give a complete description of boundary states including twisted sectors. Further we show that the GL(1|1) WZNW model is equivalent to symplectic fermions plus two scalars. We then consider the GL(1|1) boundary theory. Twisted and untwisted Cardy boundary states are constructed explicitly and their amplitudes are computed. In the twisted case we find a perturbative formulation of the model. For this purpose the introduction of an additional fermionic boundary degree of freedom is necessary. We compute all bulk one-point functions, bulk-boundary two-point functions and boundary three-point functions. Logarithmic singularities appear in bulk-boundary as well as pure boundary correlation functions. Finally we turn to world-sheet and target space supersymmetric models. There is N=2 superconformal symmetry in many supercosets and also in certain supergroups. In the supergroup case we find some branes that preserve the topological A-twist and some that preserve the B-twist.

  1. Chlorinated hydrocarbons in peat

    SciTech Connect (OSTI)

    Rapaport, R.A.


    Concentrations (ng/g), accumulation rates (ug/m/sup 2/=yr) and burdens were determined for DDT (1,1,1-trichlorophenyl2-2'bis(p-chlorophenyl)ethane), polychlorinated biphenyls. Toxaphene, hexachlorobenzene (HCB) and a,b,g-hexachlorocyclohexanes (HCHs) in peat cores taken across the mid-latitudes of North America. Because peat bogs are ombrotrophic, thereby receiving all contaminant inputs from the atmosphere and because peat cores were dated, atmospheric input functions were constructed for all of the compounds listed above excepting the HCHs. Compound inventories (burdens) in peat cores of PCBs, HCB, HCHs, Toxaphene, DDT, Pb and Zn were compared, indicating a strong influence from areas proximate to industrial sources and the atmospheric transport from source regions. Untransformed parent DDT (p,p' and o,p'-DDT) in surface peat and in precipitation provides evidence for the long range transport of DDT from neighboring countries where use has increased over the past 10-15 years. Present accumulation rates of DDT in peat are about 10-20% of maximum levels associated with peak use in the US around 1960. The DDT input function that was developed can be used to date peat cores. Transformations of DDT and PCBs were also examined in peat cores. First order transformation rates of DDT (p,p' and o,p') to DDD in anaerobic peat core environments ranged from 0.03 to 0.09 yr/sup -1/ with differences related to temperature. Aerobic transformation of PCB congeners in peat cores and microcosms was rapid for 2,3 and several 4 chlorinated congeners (T/sub 1/2 less than or equal to 0.2 to 3 years) and declined with increasing chlorine number.

  2. Delay in diagnosis of tuberculosis in Rawalpindi, Pakistan

    E-Print Network [OSTI]


    tuberculosis patients in Pakistan. J Pak Med Assoc 2008, 58(of tuberculosis in Rawalpindi, Pakistan. BMC Research Notestuberculosis in Rawalpindi, Pakistan Muhammad AN Saqib 1 ,

  3. Stakeholder Engagement in Climate Change Policymaking in American Cities

    E-Print Network [OSTI]

    Fiack, Duran; Kamieniecki , Sheldon


    s population, local water policy Journal of Environmentalparticipate in conflicts over water in particular locations.level. In contrast, the water quality issue involves

  4. Carrier heating in disordered conjugated polymers in electric field

    E-Print Network [OSTI]

    Vukmirovic, Nenad


    Carrier heating in disordered conjugated polymers inand the e?ect of carrier heating in disordered conjugatedinto the e?ect of carrier heating in conjugated polymers


    E-Print Network [OSTI]

    Sauer, Kenneth


    synthesis, Topics jn Photosynthesis, vol. 2, J. Barber,and J. R. Benemann, in Photosynthesis in Relation to ModelProcesses of Photosynthesis, Topics in Photosynthesis, vol.

  6. Historical change in coral reef communities in Caribbean Panama

    E-Print Network [OSTI]

    Cramer, Katie Lynn


    persistence interrupted in Caribbean coral reefs. EcologyJBC. Ecological change on Caribbean coral reefs before coraland extinctions in the Caribbean reef-coral fauna. In

  7. Farming in a Changing Climate: Agricultural Adaptation in Canada

    E-Print Network [OSTI]

    Jain, Varinder


    Agricultural Adaptation in Canada Ellen Wall, Barry Smit,Agricultural Adaptation in Canada. Vancouver, BC: Universitythe agri-food sector in Canada, the insights provided are so

  8. Leptons in Composite MFV

    E-Print Network [OSTI]

    Michele Redi


    We study the lepton sector of composite Higgs models with partial compositeness. The standard anarchic scenario is in conflict with the absence of observable charged lepton flavor violation. This tension can be completely solved in MFV scenarios that require either left-handed or right-handed SM leptons to be equally composite. Constraints on this scenario are weak and the composite lepton partners could be as light as few hundreds GeVs with interesting LHC signatures. The contribution to the muon (g-2) in theories where the Higgs is a pseudo Nambu-Goldstone boson is also discussed.

  9. Feral Hogs in Texas

    E-Print Network [OSTI]

    Mapston, Mark; Texas Wildlife Services


    passed. Feral hogs usually travel in family groups, or sounders, made up of two or more sows and their young. Boars are normally solitary, joining a group only to breed. 12 Food Feral hogs require high energy foods with lots of protein, so their diet... track can indicate an animal's sex or age. During the warmer months, feral hogs create wallows in moist areas. These muddy depressions help the hogs keep cool and coat them with mud that protects them from the sun and from insects. In hot weather...

  10. Buddhism in Nepal

    E-Print Network [OSTI]

    Dutt, Nalinaksha


    with consecrated water. He is asked to observe five additio nal precepts i.e. ten siksapadas in all, viz, abstention f10m enjoying dances, from use of ornamental articles, flOm sleeping on high bed, from taking food beyond fixed time, and from touching gold end... of Kathmandu on its south-east. Of these, one Caitya is in the centre of the town and four in the four corners around the twon. Caityas are just hemis pherical mounds of bricks on a brick platform. Against the sides of the Caitya there are inset vaults...

  11. Language Contact in Qumul

    E-Print Network [OSTI]

    Dwyer, Arienne M.


    Uyghur, by contrast, all of the above gerundial and non-gerundial forms have devoiced initial vowels. There are a few exceptions where devoicing in Qumul Uyghur does not occur as expected, e.g. pia:n ?at noontime prayer (Std. Uy. pein), perhaps... no longer found in modern Standard Uyghur: The present-future tense preserves the Middle Turkic suffix -adi- (cf. Chagatay -AdUr): Qumul baradimn~barimn; I go/will go cf. Std. Uy. barimn; Qumul kilimiz~kilidimiz we come/will come, cf. Std. Uy...

  12. Superradiance Transition in Graphene

    E-Print Network [OSTI]

    Alexander I. Nesterov; Fermn Aceves de la Cruz; Valeriy A. Luchnikov; Gennady P. Berman


    We study theoretically and numerically the conditions required for the appearance of a superradiance transition in graphene. The electron properties of graphene are described in the single $p_z$-orbital tight-binding approximation, in which the model is reduced to the effective two-level pseudo-spin $1/2$ system. For each level we introduce the electron transfer rate of escape into a continuum. We demonstrate that, under some conditions, the superradiance experiences the maximal quantum coherent escape to the continuum.

  13. Iodine in Texas Soils.

    E-Print Network [OSTI]

    Fraps, G. S. (George Stronach); Fudge, J. F. (Joseph Franklin)


    , while the quantity of iodine in spinach bore a close relation to the quantity of iodine in the soil. The action. of the added iodine differed with the kind of soil. Hercus and Roberts (12) state that loam has a marked retentive power for soluble... in surface soils by soil types High 1 0 1 p. *. rn. Low p. p. m. .- 1.1 ........ 1.6 2.5 0.8 1.5 ........ ........ 1.1 ........ 2.0 East Texas Timber Country Upland soils with friable subsoils: Bowie fine sandy loam...

  14. Integrity in Depth

    E-Print Network [OSTI]

    Beebe, John


    to the common problem of colluding with the attitude that shame is something to be ashamed of. He agrees with Andrew Morrison that for any in dividual with major deficits of the self, shame, not rage, is the principal affect. Beebe advocates "a psychology... is "Working on Integrity." In its opening section, "Fidelity to Process," Beebe shares a poi gnant therapeutic interchange in which he makes a mistake that leads to the patient's being angry at him. This rage facilitates the patient's discovery of her own...

  15. QCD in Extreme Environments

    E-Print Network [OSTI]

    John B. Kogut


    I review present challenges that QCD in extreme environments presents to lattice gauge theory. Recent data and impressions from RHIC are emphasized. Physical pictures of heavy ion wavefunctions, collisions and the generation of the Quark Gluon Plasma are discussed, with an eye toward engaging the lattice and its numerical methods in more interaction with the experimental and phenomenological developments. Controversial, but stimulating scenarios which can be confirmed or dismissed by lattice methods are covered. In the second half of the talk, several promising developments presented at the conference Lattice 2002 are reviewed.

  16. Chaos Models in Economics

    E-Print Network [OSTI]

    Sorin Vlad; Paul Pascu; Nicolae Morariu


    The paper discusses the main ideas of the chaos theory and presents mainly the importance of the nonlinearities in the mathematical models. Chaos and order are apparently two opposite terms. The fact that in chaos can be found a certain precise symmetry (Feigenbaum numbers) is even more surprising. As an illustration of the ubiquity of chaos, three models among many other existing models that have chaotic features are presented here: the nonlinear feedback profit model, one model for the simulation of the exchange rate and one application of the chaos theory in the capital markets.

  17. Axions in gauge mediation

    SciTech Connect (OSTI)

    Carpenter, Linda M.; Dine, Michael; Festuccia, Guido; Ubaldi, Lorenzo [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz California 95064 (United States)


    In supersymmetric theories, the presence of axions usually implies the existence of a noncompact, (pseudo)moduli space. In gauge-mediated models, the axion would seem a particularly promising dark matter candidate. The cosmology of the moduli then constrains the gravitino mass and the axion decay constant; the former cannot be much below 10 MeV; the latter cannot be much larger than 10{sup 13} GeV. Axinos, when identifiable, are typically heavy and do not play an important role in cosmology.

  18. Discrimination learning in horses

    E-Print Network [OSTI]

    Yeates, B. F


    Science DISCRIMINATION LEARNING IN HORSES A Thesis by B. F. Yeates Approved as to styIe aod content by: ~C airman oi . , Ommlttec. g ~liemoer Pe comber 1 S76 ABSTRACT Discrimination Learning in Horses (December 1976) B. F. Yeates, B. S. , Texas... was subsequently given 7 days discrimination training on each of' three different stimuli in three successive periods. Ti percert correct response" vtas used to measure period, stimuli and horse efforts. iiean percentages for the three periods were 42? 51. 9...

  19. In situ groundwater bioremediation

    SciTech Connect (OSTI)

    Hazen, Terry C.


    In situ groundwater bioremediation of hydrocarbons has been used for more than 40 years. Most strategies involve biostimulation; however, recently bioaugmentation have been used for dehalorespiration. Aquifer and contaminant profiles are critical to determining the feasibility and strategy for in situ groundwater bioremediation. Hydraulic conductivity and redox conditions, including concentrations of terminal electron acceptors are critical to determine the feasibility and strategy for potential bioremediation applications. Conceptual models followed by characterization and subsequent numerical models are critical for efficient and cost effective bioremediation. Critical research needs in this area include better modeling and integration of remediation strategies with natural attenuation.

  20. Polymers in a vacuum

    E-Print Network [OSTI]

    J. M. Deutsch


    In a variety of situations, isolated polymer molecules are found in a vacuum and here we examine their properties. Angular momentum conservation is shown to significantly alter the average size of a chain and its conservation is only broken slowly by thermal radiation. The time autocorrelation for monomer position oscillates with a characteristic time proportional to chain length. The oscillations and damping are analyzed in detail. Short range repulsive interactions suppress oscillations and speed up relaxation but stretched chains still show damped oscillatory time correlations.