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  1. GLAST Observatory Renamed for Fermi, Reveals Entire Gamma-Ray...

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

    As part of its support for particle physics research, DOE contributed funding to the ... Director of Science for High Energy Physics. "We look forward to the scientific ...

  2. The Animated Gamma-ray Sky Revealed by the Fermi Gamma-ray Space Telescope

    ScienceCinema (OSTI)

    Isabelle Grenier

    2010-01-08

    The Fermi Gamma-ray Space Telescope has been observing the sky in gamma-rays since August 2008.  In addition to breakthrough capabilities in energy coverage (20 MeV-300 GeV) and angular resolution, the wide field of view of the Large Area Telescope enables observations of 20% of the sky at any instant, and of the whole sky every three hours. It has revealed a very animated sky with bright gamma-ray bursts flashing and vanishing in minutes, powerful active galactic nuclei flaring over hours and days, many pulsars twinkling in the Milky Way, and X-ray binaries shimmering along their orbit. Most of these variable sources had not been seen by the Fermi predecessor, EGRET, and the wealth of new data already brings important clues to the origin of the high-energy emission and particles powered by the compact objects. The telescope also brings crisp images of the bright gamma-ray emission produced by cosmic-ray interactions in the interstellar medium, thus allowing to measure the cosmic nuclei and electron spectra across the Galaxy, to weigh interstellar clouds, in particular in the dark-gas phase. The telescope sensitivity at high energy will soon provide useful constraints on dark-matter annihilations in a variety of environments. I will review the current results and future prospects of the Fermi mission.

  3. NEW FERMI-LAT EVENT RECONSTRUCTION REVEALS MORE HIGH-ENERGY GAMMA RAYS FROM GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Atwood, W. B.; Baldini, L.; Bregeon, J.; Pesce-Rollins, M.; Sgro, C.; Tinivella, M.; Bruel, P.; Cohen-Tanugi, J.; Granot, J.; Longo, F.; Razzaque, S.; Zimmer, S. E-mail: nicola.omodei@stanford.edu

    2013-09-01

    Based on the experience gained during the four and a half years of the mission, the Fermi-LAT Collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet finalized, we can test the improvements in the new event reconstruction with the special case of the prompt phase of bright gamma-ray bursts (GRBs), where the signal-to-noise ratio is large enough that loose selection cuts are sufficient to identify gamma rays associated with the source. Using the new event reconstruction, we have re-analyzed 10 GRBs previously detected by the Large Area Telescope (LAT) for which an X-ray/optical follow-up was possible and found four new gamma rays with energies greater than 10 GeV in addition to the seven previously known. Among these four is a 27.4 GeV gamma ray from GRB 080916C, which has a redshift of 4.35, thus making it the gamma ray with the highest intrinsic energy ({approx}147 GeV) detected from a GRB. We present here the salient aspects of the new event reconstruction and discuss the scientific implications of these new high-energy gamma rays, such as constraining extragalactic background light models, Lorentz invariance violation tests, the prompt emission mechanism, and the bulk Lorentz factor of the emitting region.

  4. Conference: Remembering Fermi | ScienceCinema

    Office of Scientific and Technical Information (OSTI)

    Remembering Fermi Citation Details Title: Remembering Fermi

  5. Fermi Feud

    Broader source: Energy.gov [DOE]

    Enrico Fermi was the first scientist to achieve a nuclear fission chain reaction when he and a group of young scientists were experimenting at the University of Chicago on December 2, 1942. Using a “Jeopardy” format, this game features energy, electricity and nuclear science answers and questions.

  6. Enrico Fermi Patents

    Office of Scientific and Technical Information (OSTI)

    Fermi Home * Resources with Additional Information * Fermi Honored * Atoms for Peace * Centennial of Birth Marburger Speech * Stamp * AudioVideo Clips US PATENT 2,206,634 (Process ...

  7. Enrico Fermi Patents

    Office of Scientific and Technical Information (OSTI)

    Patents Fermi Home Resources with Additional Information Fermi Honored Atoms for Peace Centennial of Birth Marburger Speech Stamp AudioVideo Clips US PATENT...

  8. Reveal

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

    » Reveal Reveal Description Cray Reveal is part of the Cray Perftools software package. It utilizes the Cray CCE program library (hence it only works under PrgEnv-cray) for loopmark and source code analysis, combined with performance data collected from CrayPat. Reveal helps to identify top consuming loops, with compiler feedback on dependency and vectorization. Its loop scope analysis provides variable scope and compiler directive suggestions for inserting OpenMP parallelism to a serial or

  9. Enrico Fermi: Audio/Video Clips

    Office of Scientific and Technical Information (OSTI)

    AudioVideo Clips Fermi Home * Resources with Additional Information * Fermi Honored * Atoms for Peace * Centennial of Birth Marburger Speech * Stamp * Patents Video Clip Fermi's ...

  10. Michigan Nuclear Profile - Fermi

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

    Fermi" "Unit","Summer capacity (mw)","Net generation (thousand mwh)","Summer capacity factor (percent)","Type","Commercial operation date","License expiration date" 2,"1,085","7,738",81.4,"BWR","application/vnd.ms-excel","application/vnd.ms-excel" ,"

  11. Pairing, pseudogap and Fermi arcs in cuprates

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

    Kaminski, Adam; Kondo, Takeshi; Takeuchi, Tsunehiro; Gu, Genda

    2014-04-29

    We use Angle Resolved Photoemission Spectroscopy (ARPES) to study the relationship between the pseudogap, pairing and Fermi arcs in cuprates. High quality data measured over a wide range of dopings reveals a consistent picture of Fermiology and pairing in these materials. The pseudogap is due to an ordered state that competes with superconductivity rather than preformed pairs. Pairing does occur below Tpair ~ 150K and significantly above Tc, but well below T* and the doping dependence of this temperature scale is distinct from that of the pseudogap. The d-wave gap is present below Tpair, and its interplay with strong scatteringmore » creates “artificial” Fermi arcs for Tc ≤ T ≤ Tpair. However, above Tpair, the pseudogap exists only at the antipodal region. This leads to presence of real, gapless Fermi arcs close to the node. The length of these arcs remains constant up to T*, where the full Fermi surface is recovered. As a result, we demonstrate that these findings resolve a number of seemingly contradictory scenarios.« less

  12. Pairing, pseudogap and Fermi arcs in cuprates

    SciTech Connect (OSTI)

    Kaminski, Adam; Kondo, Takeshi; Takeuchi, Tsunehiro; Gu, Genda

    2014-04-29

    We use Angle Resolved Photoemission Spectroscopy (ARPES) to study the relationship between the pseudogap, pairing and Fermi arcs in cuprates. High quality data measured over a wide range of dopings reveals a consistent picture of Fermiology and pairing in these materials. The pseudogap is due to an ordered state that competes with superconductivity rather than preformed pairs. Pairing does occur below Tpair ~ 150K and significantly above Tc, but well below T* and the doping dependence of this temperature scale is distinct from that of the pseudogap. The d-wave gap is present below Tpair, and its interplay with strong scattering creates artificial Fermi arcs for Tc ? T ? Tpair. However, above Tpair, the pseudogap exists only at the antipodal region. This leads to presence of real, gapless Fermi arcs close to the node. The length of these arcs remains constant up to T*, where the full Fermi surface is recovered. As a result, we demonstrate that these findings resolve a number of seemingly contradictory scenarios.

  13. An Iridate with Fermi Arcs

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

    An Iridate with Fermi Arcs An Iridate with Fermi Arcs Print Wednesday, 29 October 2014 00:00 Researchers have discovered that "Fermi arcs," which are much-debated features found in the electronic structure of high-temperature superconducting (HTSC) cuprates, can also be found in an iridate (iridium oxide) compound. At the ALS, the researchers observed the electronic structure of strontium iridate as it evolved through different doping levels and temperatures by using angle-resolved

  14. An Iridate with Fermi Arcs

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

    of a broken Fermi surface. In conventional superconductors, the superconducting gap-an indicator of superconductivity-vanishes above the superconducting transition temperature...

  15. Named Fellowships Luminary - Enrico Fermi | Argonne National...

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

    Enrico Fermi Enrico Fermi was born in Rome, Italy on September 29, 1901. Fermi was an Italian physicist, best known for having built the Chicago Pile-1 (the first nuclear...

  16. Unconventional Fermi surface in an insulating state

    SciTech Connect (OSTI)

    Harrison, Neil; Tan, B. S.; Hsu, Y. -T.; Zeng, B.; Hatnean, M. Ciomaga; Zhu, Z.; Hartstein, M.; Kiourlappou, M.; Srivastava, A.; Johannes, M. D.; Murphy, T. P.; Park, J. -H.; Balicas, L.; Lonzarich, G. G.; Balakrishnan, G.; Sebastian, Suchitra E.

    2015-07-17

    Insulators occur in more than one guise; a recent finding was a class of topological insulators, which host a conducting surface juxtaposed with an insulating bulk. Here, we report the observation of an unusual insulating state with an electrically insulating bulk that simultaneously yields bulk quantum oscillations with characteristics of an unconventional Fermi liquid. We present quantum oscillation measurements of magnetic torque in high-purity single crystals of the Kondo insulator SmB6, which reveal quantum oscillation frequencies characteristic of a large three-dimensional conduction electron Fermi surface similar to the metallic rare earth hexaborides such as PrB6 and LaB6. As a result, the quantum oscillation amplitude strongly increases at low temperatures, appearing strikingly at variance with conventional metallic behavior.

  17. An Iridate with Fermi Arcs

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

    An Iridate with Fermi Arcs Print Researchers have discovered that "Fermi arcs," which are much-debated features found in the electronic structure of high-temperature superconducting (HTSC) cuprates, can also be found in an iridate (iridium oxide) compound. At the ALS, the researchers observed the electronic structure of strontium iridate as it evolved through different doping levels and temperatures by using angle-resolved photoemission spectroscopy (ARPES) with in situ electron doping

  18. An Iridate with Fermi Arcs

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

    An Iridate with Fermi Arcs Print Researchers have discovered that "Fermi arcs," which are much-debated features found in the electronic structure of high-temperature superconducting (HTSC) cuprates, can also be found in an iridate (iridium oxide) compound. At the ALS, the researchers observed the electronic structure of strontium iridate as it evolved through different doping levels and temperatures by using angle-resolved photoemission spectroscopy (ARPES) with in situ electron doping

  19. An Iridate with Fermi Arcs

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

    An Iridate with Fermi Arcs Print Researchers have discovered that "Fermi arcs," which are much-debated features found in the electronic structure of high-temperature superconducting (HTSC) cuprates, can also be found in an iridate (iridium oxide) compound. At the ALS, the researchers observed the electronic structure of strontium iridate as it evolved through different doping levels and temperatures by using angle-resolved photoemission spectroscopy (ARPES) with in situ electron doping

  20. An Iridate with Fermi Arcs

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

    An Iridate with Fermi Arcs Print Researchers have discovered that "Fermi arcs," which are much-debated features found in the electronic structure of high-temperature superconducting (HTSC) cuprates, can also be found in an iridate (iridium oxide) compound. At the ALS, the researchers observed the electronic structure of strontium iridate as it evolved through different doping levels and temperatures by using angle-resolved photoemission spectroscopy (ARPES) with in situ electron doping

  1. An Iridate with Fermi Arcs

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

    An Iridate with Fermi Arcs Print Researchers have discovered that "Fermi arcs," which are much-debated features found in the electronic structure of high-temperature superconducting (HTSC) cuprates, can also be found in an iridate (iridium oxide) compound. At the ALS, the researchers observed the electronic structure of strontium iridate as it evolved through different doping levels and temperatures by using angle-resolved photoemission spectroscopy (ARPES) with in situ electron doping

  2. An Iridate with Fermi Arcs

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

    An Iridate with Fermi Arcs Print Researchers have discovered that "Fermi arcs," which are much-debated features found in the electronic structure of high-temperature superconducting (HTSC) cuprates, can also be found in an iridate (iridium oxide) compound. At the ALS, the researchers observed the electronic structure of strontium iridate as it evolved through different doping levels and temperatures by using angle-resolved photoemission spectroscopy (ARPES) with in situ electron doping

  3. An Iridate with Fermi Arcs

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

    An Iridate with Fermi Arcs Print Researchers have discovered that "Fermi arcs," which are much-debated features found in the electronic structure of high-temperature superconducting (HTSC) cuprates, can also be found in an iridate (iridium oxide) compound. At the ALS, the researchers observed the electronic structure of strontium iridate as it evolved through different doping levels and temperatures by using angle-resolved photoemission spectroscopy (ARPES) with in situ electron doping

  4. Enrico Fermi's Impact on Science - John Marburger Speech

    Office of Scientific and Technical Information (OSTI)

    Fermi Home * Resources with Additional Information * Fermi Honored * Atoms for Peace * Centennial of Birth Stamp * Patents * AudioVideo Clips Enrico Fermi's Impact on Science ...

  5. FermiCulture Subscription Form

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

    The FermiCulture email list is used to send email announcements and reminders about upcoming cultural events at Fermilab (e.g., the Fermilab Arts, Film, and Lecture series). This is a private, announcement-only mail list and will never be used for spamming or discussions. Subscribers receive approximately five emails per month. Use the form below to subscribe to (or unsubscribe from) the FermiCulture list. Email address: Name (First Last): Subscribe to email list Unsubscribe from email list Send

  6. Phoenix Convention Center * Phoenix, Arizona Playing the Entire...

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

    Phoenix, Arizona Playing the Entire Value Chain for Energy Storage Session 6: Innovation ... Critical infrastructure project - Davis-Monthan AFB, AZ AxionPower - one MW battery ...

  7. Fermi Award Winners Saluted | Department of Energy

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

    Fermi Award Winners Saluted Fermi Award Winners Saluted May 9, 2012 - 3:18pm Addthis President Barack Obama greets 2010 Fermi Award recipients Dr. Burton Richter, right, and his wife Laurose, and Dr. Mildred S. Dresselhaus, third from right, and her husband Gene, in the Oval Office, May 7, 2012. (Official White House Photo by Pete Souza) President Barack Obama greets 2010 Fermi Award recipients Dr. Burton Richter, right, and his wife Laurose, and Dr. Mildred S. Dresselhaus, third from right, and

  8. Fermi Timing and Synchronization System

    SciTech Connect (OSTI)

    Wilcox, R.; Staples, J.; Doolittle, L.; Byrd, J.; Ratti, A.; Kaertner, F.X.; Kim, J.; Chen, J.; Ilday, F.O.; Ludwig, F.; Winter, A.; Ferianis, M.; Danailov, M.; D'Auria, G.

    2006-07-19

    The Fermi FEL will depend critically on precise timing of its RF, laser and diagnostic subsystems. The timing subsystem to coordinate these functions will need to reliably maintain sub-100fs synchronicity between distant points up to 300m apart in the Fermi facility. The technology to do this is not commercially available, and has not been experimentally demonstrated in a working facility. Therefore, new technology must be developed to meet these needs. Two approaches have been researched by different groups working with the Fermi staff. At MIT, a pulse transmission scheme has been developed for synchronization of RF and laser devices. And at LBL, a CW transmission scheme has been developed for RF and laser synchronization. These respective schemes have advantages and disadvantages that will become better understood in coming years. This document presents the work done by both teams, and suggests a possible system design which integrates them both. The integrated system design provides an example of how choices can be made between the different approaches without significantly changing the basic infrastructure of the system. Overall system issues common to any synchronization scheme are also discussed.

  9. Entirely passive heat pipe apparatus capable of operating against gravity

    DOE Patents [OSTI]

    Koenig, Daniel R. (Santa Fe, NM)

    1982-01-01

    The disclosure is directed to an entirely passive heat pipe apparatus capable of operating against gravity for vertical distances in the order of 3 to 7 meters and more. A return conduit into which an inert gas is introduced is used to lower the specific density of the working fluid so that it may be returned a greater vertical distance from condenser to evaporator.

  10. Fermi arcs vs. fermi pockets in electron-doped perovskite iridates (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect SciTech Connect Search Results Journal Article: Fermi arcs vs. fermi pockets in electron-doped perovskite iridates Citation Details In-Document Search Title: Fermi arcs vs. fermi pockets in electron-doped perovskite iridates We report on an angle resolved photoemission (ARPES) study of bulk electron-doped perovskite iridate, (Sr1-xLax)₃Ir₂O₇. Fermi surface pockets are observed with a total electron count in keeping with that expected from La substitution.

  11. Fermi Energy Tuning with Light to Control Doping Profiles During...

    Office of Scientific and Technical Information (OSTI)

    Fermi Energy Tuning with Light to Control Doping Profiles During Epitaxy; Article No. 182105 Citation Details In-Document Search Title: Fermi Energy Tuning with Light to Control ...

  12. Generalized charge-screening in relativistic ThomasFermi model

    SciTech Connect (OSTI)

    Akbari-Moghanjoughi, M.

    2014-10-15

    In this paper, we study the charge shielding within the relativistic Thomas-Fermi model for a wide range of electron number-densities and the atomic-number of screened ions. A generalized energy-density relation is obtained using the force-balance equation and taking into account the Chandrasekhar's relativistic electron degeneracy pressure. By numerically solving a second-order nonlinear differential equation, the Thomas-Fermi screening length is investigated, and the results are compared for three distinct regimes of the solid-density, warm-dense-matter, and white-dwarfs (WDs). It is revealed that our nonlinear screening theory is compatible with the exponentially decaying Thomas-Fermi-type shielding predicted by the linear response theory. Moreover, the variation of relative Thomas-Fermi screening length shows that extremely dense quantum electron fluids are relatively poor charge shielders. Calculation of the total number of screening electrons around a nucleus shows that there is a position of maximum number of screening localized electrons around the screened nucleus, which moves closer to the point-like nucleus by increase in the plasma number density but is unaffected due to increase in the atomic-number value. It is discovered that the total number of screening electrons, (N{sub s}?r{sub TF}{sup 3}/r{sub d}{sup 3} where r{sub TF} and r{sub d} are the Thomas-Fermi and interparticle distance, respectively) has a distinct limit for extremely dense plasmas such as WD-cores and neutron star crusts, which is unique for all given values of the atomic-number. This is equal to saying that in an ultrarelativistic degeneracy limit of electron-ion plasma, the screening length couples with the system dimensionality and the plasma becomes spherically self-similar. Current analysis can provide useful information on the effects of relativistic correction to the charge screening for a wide range of plasma density, such as the inertial-confined plasmas and compact stellar objects.

  13. Hunting for treasures among the Fermi unassociated sources: A multiwavelength approach

    SciTech Connect (OSTI)

    Acero, F.; Ojha, R.; Edwards, P. G.; Blanchard, J.; Lovell, J. E. J.; Thompson, D. J.

    2013-12-20

    The Fermi Gamma-Ray Space Telescope has been detecting a wealth of sources where the multiwavelength counterpart is either inconclusive or missing altogether. We present a combination of factors that can be used to identify multiwavelength counterparts to these Fermi unassociated sources. This approach was used to select and investigate seven bright, high-latitude unassociated sources with radio, UV, X-ray, and ?-ray observations. As a result, four of these sources are candidates to be active galactic nuclei, and one to be a pulsar, while two do not fit easily into these known categories of sources. The latter pair of extraordinary sources might reveal a new category subclass or a new type of ?-ray emitter. These results altogether demonstrate the power of a multiwavelength approach to illuminate the nature of unassociated Fermi sources.

  14. Traveling dark solitons in superfluid Fermi gases

    SciTech Connect (OSTI)

    Liao Renyuan; Brand, Joachim

    2011-04-15

    Families of dark solitons exist in superfluid Fermi gases. The energy-velocity dispersion and number of depleted particles completely determine the dynamics of dark solitons on a slowly varying background density. For the unitary Fermi gas, we determine these relations from general scaling arguments and conservation of local particle number. We find solitons to oscillate sinusoidally at the trap frequency reduced by a factor of 1/{radical}(3). Numerical integration of the time-dependent Bogoliubov-de Gennes equation determines spatial profiles and soliton-dispersion relations across the BEC-BCS crossover, and proves consistent with the scaling relations at unitarity.

  15. Enrico Fermi Award Ceremony | Department of Energy

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

    Enrico Fermi Award Ceremony Enrico Fermi Award Ceremony June 22, 2006 - 2:31pm Addthis Remarks Prepared for Energy Secretary Samuel Bodman The Department of Energy has a very rich scientific tradition and one of the best things about being Energy Secretary is from time to time I have an opportunity to acknowledge that tradition and the very real impact it continues to have on the lives of all Americans.Today is one of those days. We are here to honor Art Rosenfeld with our nation's highest

  16. Maximal Cherenkov ?-radiation on Fermi-surface of compact stars

    SciTech Connect (OSTI)

    Akbari-Moghanjoughi, M.

    2014-05-15

    The quantum magnetohydrodynamic model is employed in this paper to study the extraordinary (XO) elliptically polarized electromagnetic wave dispersion in quantum plasmas with spin-1/2 magnetization and relativistic degeneracy effects, considering also the electron-exchange and quantum diffraction of electrons. From the lower and upper calculated XO-modes, it is observed that, for electrons on the surface of the Fermi-sphere, the lower XO-mode can excite the Cherenkov radiation by crossing the Fermi-line, with some proper conditions depending on the values of independent plasma parameters, such as the relativistic-degeneracy, the atomic-number of constituent ions, and the magnetic field strength. Particularly, a lower electron number-density and Cherenkov radiation frequency limits are found to exist, for instance, for given values of the plasma ions atomic-number and the magnetic field strength below which the radiation can not be excited by the electrons on the Fermi-surface. This lower density limit increases by decrease in the atomic-number but decreases with decrease in the strength of the ambient magnetic field. It is remarkable that in this research it is discovered that the maximal Cherenkov-radiation per unit-length (the energy radiated by superluminal electrons traveling through the dielectric medium) coincides with the plasma number-densities, which is present in compact stars with the maximal radiation frequency lying in the gamma-ray spectrum. Current study can provide an important plasma diagnostic tool for a wide plasma density range, be it the solid density, the warm dense matter, the inertial confined or the astrophysical compact plasmas and may reveal an important cooling mechanism for white dwarfs. Current findings may also answer the fundamental astrophysical question on the mysterious origin of intense cosmic gamma-ray emissions.

  17. 2013 Annual Planning Summary for the FERMI Site Office

    Broader source: Energy.gov [DOE]

    The ongoing and projected Environmental Assessments and Environmental Impact Statements for 2013 and 2014 within the FERMI Site Office.

  18. 2012 Annual Planning Summary for Fermi Site Office

    Broader source: Energy.gov [DOE]

    The ongoing and projected Environmental Assessments and Environmental Impact Statements for 2012 and 2013 within Fermi Site Office.

  19. FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG

    SciTech Connect (OSTI)

    Nolan, P. L.; Ajello, M.; Allafort, A.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Abdo, A. A.; Ackermann, M.; Antolini, E.; Bonamente, E.; Atwood, W. B.; Belfiore, A.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Ballet, J.; Bastieri, D.; Bignami, G. F. E-mail: Gino.Tosti@pg.infn.it E-mail: tburnett@u.washington.edu; and others

    2012-04-01

    We present the second catalog of high-energy {gamma}-ray sources detected by the Large Area Telescope (LAT), the primary science instrument on the Fermi Gamma-ray Space Telescope (Fermi), derived from data taken during the first 24 months of the science phase of the mission, which began on 2008 August 4. Source detection is based on the average flux over the 24 month period. The second Fermi-LAT catalog (2FGL) includes source location regions, defined in terms of elliptical fits to the 95% confidence regions and spectral fits in terms of power-law, exponentially cutoff power-law, or log-normal forms. Also included are flux measurements in five energy bands and light curves on monthly intervals for each source. Twelve sources in the catalog are modeled as spatially extended. We provide a detailed comparison of the results from this catalog with those from the first Fermi-LAT catalog (1FGL). Although the diffuse Galactic and isotropic models used in the 2FGL analysis are improved compared to the 1FGL catalog, we attach caution flags to 162 of the sources to indicate possible confusion with residual imperfections in the diffuse model. The 2FGL catalog contains 1873 sources detected and characterized in the 100 MeV to 100 GeV range of which we consider 127 as being firmly identified and 1171 as being reliably associated with counterparts of known or likely {gamma}-ray-producing source classes.

  20. Enrico Fermi Achieves First Self Sustain Nuclear Chain Reaction | National

    National Nuclear Security Administration (NNSA)

    Nuclear Security Administration Enrico Fermi Achieves First Self Sustain Nuclear Chain Reaction Enrico Fermi Achieves First Self Sustain Nuclear Chain Reaction Chicago, IL Metallurgical Laboratory scientists led by Enrico Fermi achieve the first self-sustained nuclear chain reaction in pile constructed under the west grandstand at Stagg field in Chicago

  1. 2016_FEB.FermiOrgChart

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

    Organization Fermi Research Alliance, LLC Neutrino Division Gina Rameika Particle Physics Division Patricia McBride Office of the CRO Joe Lykken Chief Research Officer Fermilab Center for Particle Astrophysics Craig Hogan CMS Center Kevin Burkett Office of the General Counsel John Myer Office of Integrated Planning & Performance Management Erik Gottschalk Workforce Development & Resources Section Kay Van Vreede Office of the COO Timothy Meyer Chief Operating Officer Office of

  2. Fermi large area telescope observations of blazar 3C 279 occultations by the sun

    SciTech Connect (OSTI)

    Barbiellini, G.; Bastieri, D.; Buson, S.; Bechtol, K.; Blandford, R. D.; Borgland, A. W.; Buehler, R.; Cameron, R. A.; Chiang, J.; Bellazzini, R.; Bregeon, J.; Bruel, P.; Caraveo, P. A.; Cavazzuti, E.; Ciprini, S.; Cecchi, C.; Chaves, R. C. G.; Cheung, C. C. E-mail: phdmitry@stanford.edu; and others

    2014-04-01

    Observations of occultations of bright ?-ray sources by the Sun may reveal predicted pair halos around blazars and/or new physics, such as, e.g., hypothetical light dark matter particlesaxions. We use Fermi Gamma-Ray Space Telescope (Fermi) data to analyze four occultations of blazar 3C 279 by the Sun on October 8 each year from 2008 to 2011. A combined analysis of the observations of these occultations allows a point-like source at the position of 3C 279 to be detected with significance of ?3?, but does not reveal any significant excess over the flux expected from the quiescent Sun. The likelihood ratio test rules out complete transparency of the Sun to the blazar ?-ray emission at a 3? confidence level.

  3. Fermi arcs vs. fermi pockets in electron-doped perovskite iridates

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

    He, Junfeng; Hafiz, H.; Mion, Thomas R.; Hogan, T.; Dhital, C.; Chen, X.; Lin, Qisen; Hashimoto, M.; Lu, D. H.; Zhang, Y.; et al

    2015-02-23

    We report on an angle resolved photoemission (ARPES) study of bulk electron-doped perovskite iridate, (Sr1-xLax)₃Ir₂O₇. Fermi surface pockets are observed with a total electron count in keeping with that expected from La substitution. Depending on the energy and polarization of the incident photons, these pockets show up in the form of disconnected “Fermi arcs”, reminiscent of those reported recently in surface electron-doped Sr₂IrO₄. Our observed spectral variation is consistent with the coexistence of an electronic supermodulation with structural distortion in the system.

  4. Towards a Holographic Marginal Fermi Liquid (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    Language: English Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; BRANES; DEFECTS; FERMI GAS; FERMIONS; FIELD THEORIES; ...

  5. 2011 Annual Planning Summary for Fermi Site Office (FSO)

    Broader source: Energy.gov [DOE]

    The ongoing and projected Environmental Assessments and Environmental Impact Statements for 2011 and 2012 within the Fermi Site Office (See Science APS).

  6. Enrico Fermi Achieves First Self Sustain Nuclear Chain Reaction...

    National Nuclear Security Administration (NNSA)

    Self Sustain Nuclear Chain Reaction Chicago, IL Metallurgical Laboratory scientists led by Enrico Fermi achieve the first self-sustained nuclear chain reaction in pile...

  7. I Fermi National Accelerator Laboratory I I

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

    b .?.? ... . . 1- \r I Fermi National Accelerator Laboratory I I FERMILAB-Cdnf-76 159 -EXP 2 020,000 2 02 2.000 I 1 (Submitted to the Neutrino I 9 76 Conference Aachen, Germany June 8r-13, -1976) * I 4 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or assumes any legal liability or responsibility for the

  8. Fermi LAT Observations of LS 5039

    SciTech Connect (OSTI)

    Abdo, A.A.; Ackermann, M.; Ajello, M.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B.M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R.D.; Bloom, E.D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; /more authors..

    2012-03-29

    The first results from observations of the high-mass X-ray binary LS 5039 using the Fermi Gamma-ray Space Telescope data between 2008 August and 2009 June are presented. Our results indicate variability that is consistent with the binary period, with the emission being modulated with a period of 3.903 {+-} 0.005 days; the first detection of this modulation at GeV energies. The light curve is characterized by a broad peak around superior conjunction in agreement with inverse Compton scattering models. The spectrum is represented by a power law with an exponential cutoff, yielding an overall flux (100 MeV-300 GeV) of 4.9 {+-} 0.5(stat) {+-} 1.8(syst) x 10{sup -7} photon cm{sup -2} s{sup -1}, with a cutoff at 2.1 {+-} 0.3(stat) {+-} 1.1(syst) GeV and photon index {Gamma} = 1.9 {+-} 0.1(stat) {+-} 0.3(syst). The spectrum is observed to vary with orbital phase, specifically between inferior and superior conjunction. We suggest that the presence of a cutoff in the spectrum may be indicative of magnetospheric emission similar to the emission seen in many pulsars by Fermi.

  9. "Where is Everybody?" An Account of Fermi's Question

    DOE R&D Accomplishments [OSTI]

    Jones, E. M.

    1985-03-01

    Enrico Fermi's famous question, now central to debates about the prevalence of extraterrestrial civilizations, arose during a luncheon conversation with Emil Konopinski, Edward Teller, and Herbert York in the summer of 1950. Fermi's companions on that day have provided accounts of the incident.

  10. Chiral asymmetry of the Fermi surface in dense relativistic matter in a magnetic field

    SciTech Connect (OSTI)

    Gorbar, E. V.; Miransky, V. A.; Shovkovy, I. A.

    2009-09-15

    It is revealed that in the normal phase of dense relativistic matter in a magnetic field, there exists a contribution to the axial current associated with a relative shift of the longitudinal momenta in the dispersion relations of opposite chirality fermions. Unlike the topological contribution in the axial current at the lowest Landau level, recently discussed in the literature, the dynamical one appears only in interacting matter and affects the fermions in all Landau levels, including those around the Fermi surface. The induced axial current and the shift of the Fermi surfaces of the left-handed and right-handed fermions are expected to play an important role in transport and emission properties of matter in various types of compact stars as well as in heavy ion collisions.

  11. The Life of Enrico Fermi | U.S. DOE Office of Science (SC)

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

    The Life of Enrico Fermi The Enrico Fermi Award Fermi Award Home Nomination & Selection Guidelines Award Laureates Ceremony The Life of Enrico Fermi Contact Information The Enrico Fermi Award U.S. Department of Energy SC-2/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-2411 E: Email Us The Life of Enrico Fermi Print Text Size: A A A FeedbackShare Page Enrico Fermi Click for a story about the photograph On December 2, 1942, Enrico Fermi and his team of

  12. Momentum sharing in imbalanced Fermi systems

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

    Hen, O.; Sargsian, M.; Weinstein, L. B.; Piasetzky, E.

    2014-10-16

    The atomic nucleus is composed of two different kinds of fermions, protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority fermions (usually neutrons) to have a higher average momentum. Our high-energy electron scattering measurements using 12C, 27Al, 56Fe and 208Pb targets show that, even in heavy neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few body systems to neutron starsmore » and may also be observable experimentally in two-spin state, ultra-cold atomic gas systems.« less

  13. Momentum sharing in imbalanced Fermi systems

    SciTech Connect (OSTI)

    Hen, O. [Tel Aviv Univ., Tel Aviv (Israel); Sargsian, M. [Florida International Univ., Miami, FL (United States); Weinstein, L. B. [Old Dominion Univ., Norfolk, VA (United States); Piasetzky, E. [Tel Aviv Univ., Tel Aviv (Israel), et. al.

    2014-10-30

    The atomic nucleus is composed of two different kinds of fermions, protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority fermions (usually neutrons) to have a higher average momentum. Our high-energy electron scattering measurements using 12C, 27Al, 56Fe and 208Pb targets show that, even in heavy neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few body systems to neutron stars and may also be observable experimentally in two-spin state, ultra-cold atomic gas systems.

  14. Fermi-liquid damping and NMR relaxation in superconductors

    SciTech Connect (OSTI)

    Tewari, S.; Ruvalds, J.

    1996-03-01

    Electron collisions for a two-dimensional Fermi-liquid (FL) are shown to give a quasiparticle damping with interesting frequency and temperature variations in the BCS superconducting state. The spin susceptibility which determines the structure of the damping is analyzed in the normal state for a Hubbard model with a constant on-site Coulomb repulsion. This is then generalized to the superconducting state by including coherence factors and self-energy and vertex corrections. Calculations of the NMR relaxation rate reveal that the FL damping structure can reduce the Hebel-Slichter peak, in agreement with data on the organic superconductor (MDT-TTF){sub 2}AuI{sub 2} (methylenedithiotetrathiafulvalene salt). However, the strongly suppressed FL damping in the superconducting state does not eliminate the Hebel-Slichter peak, and thus suggests that other mechanisms are needed to explain the NMR data on (TMTSF){sub 2}ClO{sub 4} (bistetramethyltetraselenafulvaleneperchlorate), the BEDT organic compounds, and cuprate superconductors. Predictions of the temperature variation of the damping and the spin response are given over a wide frequency range as a guide to experimental probes of the symmetry of the superconducting pairs. {copyright} {ital 1996 The American Physical Society.}

  15. Video: Honoring Science that Matters with the Enrico Fermi Award |

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

    Department of Energy Honoring Science that Matters with the Enrico Fermi Award Video: Honoring Science that Matters with the Enrico Fermi Award February 11, 2014 - 9:50am Addthis The Fermi Award is a Presidential award and is one of the oldest and most prestigious science and technology honors bestowed by the U.S. Government. The 2013 winners of the award are Dr. Allen J. Bard, of The University of Texas at Austin, and Dr. Andrew Sessler of the Lawrence Berkeley National Laboratory. Ben

  16. Quantum fluctuations in the BCS-BEC crossover of two-dimensional Fermi gases

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

    He, Lianyi; Lu, Haifeng; Cao, Gaoqing; Hu, Hui; Liu, Xia -Ji

    2015-08-14

    We present a theoretical study of the ground state of the BCS-BEC crossover in dilute two-dimensional Fermi gases. While the mean-field theory provides a simple and analytical equation of state, the pressure is equal to that of a noninteracting Fermi gas in the entire BCS-BEC crossover, which is not consistent with the features of a weakly interacting Bose condensate in the BEC limit and a weakly interacting Fermi liquid in the BCS limit. The inadequacy of the two-dimensional mean-field theory indicates that the quantum fluctuations are much more pronounced than those in three dimensions. In this work, we show thatmore » the inclusion of the Gaussian quantum fluctuations naturally recovers the above features in both the BEC and the BCS limits. In the BEC limit, the missing logarithmic dependence on the boson chemical potential is recovered by the quantum fluctuations. Near the quantum phase transition from the vacuum to the BEC phase, we compare our equation of state with the known grand canonical equation of state of two-dimensional Bose gases and determine the ratio of the composite boson scattering length aB to the fermion scattering length a2D. We find aB ≃ 0.56a2D, in good agreement with the exact four-body calculation. As a result, we compare our equation of state in the BCS-BEC crossover with recent results from the quantum Monte Carlo simulations and the experimental measurements and find good agreements.« less

  17. Fermi Large Area Telescope Observations of the Supernova Remnant...

    Office of Scientific and Technical Information (OSTI)

    Fermi Large Area Telescope Observations of the Supernova Remnant G8.7-0.1 Citation Details ... Language: English Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 72 PHYSICS ...

  18. Enrico Fermi's Impact on Science - John Marburger Speech

    Office of Scientific and Technical Information (OSTI)

    essentials. Later, when I came to know Fermi and Dirac, I realized that they spoke and thought about physics very much in the way that I had imagined them to do from studying...

  19. "Doing Business with Argonne and Fermi National Laboratories...

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

    "Doing Business with Argonne and Fermi National Laboratories" 2014 Argonne-Fermilab Small Business Fair 1 of 20 2014 Argonne-Fermilab Small Business Fair On Aug. 28, 2014, Argonne...

  20. Phase Imprinting in Equilibrating Fermi Gases: The Transience of Vortex

    Office of Scientific and Technical Information (OSTI)

    Rings and Other Defects (Journal Article) | DOE PAGES Phase Imprinting in Equilibrating Fermi Gases: The Transience of Vortex Rings and Other Defects « Prev Next » Title: Phase Imprinting in Equilibrating Fermi Gases: The Transience of Vortex Rings and Other Defects Authors: Scherpelz, Peter ; Padavić, Karmela ; Rançon, Adam ; Glatz, Andreas ; Aranson, Igor S. ; Levin, K. Publication Date: 2014-09-16 OSTI Identifier: 1180434 Type: Publisher's Accepted Manuscript Journal Name: Physical

  1. Phase Imprinting in Equilibrating Fermi Gases: The Transience of Vortex

    Office of Scientific and Technical Information (OSTI)

    Rings and Other Defects (Journal Article) | SciTech Connect Phase Imprinting in Equilibrating Fermi Gases: The Transience of Vortex Rings and Other Defects Citation Details In-Document Search Title: Phase Imprinting in Equilibrating Fermi Gases: The Transience of Vortex Rings and Other Defects Authors: Scherpelz, Peter ; Padavić, Karmela ; Rançon, Adam ; Glatz, Andreas ; Aranson, Igor S. ; Levin, K. Publication Date: 2014-09-16 OSTI Identifier: 1180434 Type: Publisher's Accepted Manuscript

  2. Entirely passive heat-pipe apparatus capable of operating against gravity

    DOE Patents [OSTI]

    Koenig, D.R.

    1981-02-11

    The disclosure is directed to an entirely passive heat pipe apparatus capable of operating against gravity for vertical distances in the order of 3 to 7 and more. A return conduit into which an inert gas is introduced is used to lower the specific density of the working fluid so that it may be returned a greater vertical distance from condenser to evaporator.

  3. Correlation between Fermi surface transformations and superconductivity in

    Office of Scientific and Technical Information (OSTI)

    the electron-doped high- T c superconductor Nd 2 - x Ce x CuO 4 (Journal Article) | SciTech Connect Journal Article: Correlation between Fermi surface transformations and superconductivity in the electron-doped high- T c superconductor Nd 2 - x Ce x CuO 4 Citation Details In-Document Search This content will become publicly available on August 31, 2016 Title: Correlation between Fermi surface transformations and superconductivity in the electron-doped high- T c superconductor Nd 2 - x Ce x

  4. Fermi Site Office Homepage | U.S. DOE Office of Science (SC)

    Office of Science (SC) Website

    Home Fermi Site Office (FSO) FSO Home About Projects Contract Management NEPA Documents Resources Contact Information Fermi Site Office U.S. Department of Energy MS 118 P.O. Box ...

  5. The Search of Axion-Like-Particles With Fermi and Cherenkov Telescopes...

    Office of Scientific and Technical Information (OSTI)

    The Search of Axion-Like-Particles With Fermi and Cherenkov Telescopes Citation Details In-Document Search Title: The Search of Axion-Like-Particles With Fermi and Cherenkov...

  6. Kondo effect and non-Fermi-liquid behavior in Dirac and Weyl...

    Office of Scientific and Technical Information (OSTI)

    Kondo effect and non-Fermi-liquid behavior in Dirac and Weyl semimetals Citation Details ... Title: Kondo effect and non-Fermi-liquid behavior in Dirac and Weyl semimetals Authors: ...

  7. Kondo effect and non-Fermi-liquid behavior in Dirac and Weyl...

    Office of Scientific and Technical Information (OSTI)

    non-Fermi-liquid behavior in Dirac and Weyl semimetals This content will become publicly available on July 7, 2016 Title: Kondo effect and non-Fermi-liquid behavior in Dirac and ...

  8. Fermi Gamma-Ray Space Telescope: High-Energy Results From the...

    Office of Scientific and Technical Information (OSTI)

    Fermi Gamma-Ray Space Telescope: High-Energy Results From the First Year Citation Details In-Document Search Title: Fermi Gamma-Ray Space Telescope: High-Energy Results From the ...

  9. Enrico Fermi Award Nominations | U.S. DOE Office of Science (SC)

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

    Nuclear Security Administration Enrico Fermi Achieves First Self Sustain Nuclear Chain Reaction Enrico Fermi Achieves First Self Sustain Nuclear Chain Reaction Chicago, IL Metallurgical Laboratory scientists led by Enrico Fermi achieve the first self-sustained nuclear chain reaction in pile constructed under the west grandstand at Stagg field in Chicago

    Enrico Fermi Award Nominations News News Home Featured Articles Science Headlines 2016 2015 2014 2013 2012 2011 2010 2009 2008 2007 2006

  10. Fermi National Accelerator Laboratory FERMILAB-Conf-94/419-E

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

    Fermi Award Winners Saluted Fermi Award Winners Saluted May 9, 2012 - 3:18pm Addthis President Barack Obama greets 2010 Fermi Award recipients Dr. Burton Richter, right, and his wife Laurose, and Dr. Mildred S. Dresselhaus, third from right, and her husband Gene, in the Oval Office, May 7, 2012. (Official White House Photo by Pete Souza) President Barack Obama greets 2010 Fermi Award recipients Dr. Burton Richter, right, and his wife Laurose, and Dr. Mildred S. Dresselhaus, third from right, and

  11. A Southern Sky Survey with Fermi LAT and ASKAP

    SciTech Connect (OSTI)

    Cameron, Robert A.; /SLAC /KIPAC, Menlo Park

    2010-04-29

    We present the prospects for a future joint gamma-ray and radio survey of southern hemisphere sources using the Fermi Large Area Telescope (LAT) and the upcoming Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope. ASKAP is a next generation radio telescope designed to perform surveys at GHz frequencies at a much higher survey speed than previous radio telescopes, and is scheduled to start engineering observations in 2011. The survey capabilities of both Fermi LAT and ASKAP are described, and the planned science surveys for ASKAP are summarized. We give some expected details of the Variable and Slow Transient (VAST) survey using ASKAP, which will search for transients on timescales from 5 seconds to years. Some observational properties of faint and transient sources seen at gamma-ray and radio wavelengths are summarized, and prospects and strategies for using ASKAP survey data for LAT source counterpart identification are summarized.

  12. Unconventional interaction between vortices in a polarized Fermi gas

    SciTech Connect (OSTI)

    Stojanovic, Vladimir M.; Vincent Liu, W. Kim, Yong Baek

    2008-04-15

    Recently, a homogeneous superfluid state with a single gapless Fermi surface was predicted to be the ground state of an ultracold Fermi gas with spin population imbalance in the regime of molecular Bose-Einstein condensation. We study vortices in this novel state using a symmetry-based effective field theory, which captures the low-energy physics of gapless fermions and superfluid phase fluctuations. This theory is applicable to all spin-imbalanced ultracold Fermi gases in the superfluid regime, regardless of whether the original fermion-pairing interaction is weak or strong. We find a remarkable, unconventional form of the interaction between vortices. The presence of gapless fermions gives rise to a spatially oscillating potential, akin to the RKKY indirect-exchange interaction in non-magnetic metals. We compare the parameters of the effective theory to the experimentally measurable quantities and further discuss the conditions for the verification of the predicted new feature. Our study opens up an interesting question as to the nature of the vortex lattice resulting from the competition between the usual repulsive logarithmic (2D Coulomb) and predominantly attractive fermion-induced interactions.

  13. CLUSTERING OF ?-RAY-SELECTED 2LAC FERMI BLAZARS

    SciTech Connect (OSTI)

    Allevato, V.; Finoguenov, A.; Cappelluti, N.

    2014-12-20

    We present the first measurement of the projected correlation function of 485 ?-ray-selected blazars, divided into 175 BL Lacertae (BL Lacs) and 310 flat-spectrum radio quasars (FSRQs) detected in the 2 year all-sky survey by the Fermi-Large Area Telescope. We find that Fermi BL Lacs and FSRQs reside in massive dark matter halos (DMHs) with log M{sub h} = 13.35{sub ?0.14}{sup +0.20} and log M{sub h} = 13.40{sub ?0.19}{sup +0.15} h {sup 1} M {sub ?}, respectively, at low (z ? 0.4) and high (z ? 1.2) redshift. In terms of clustering properties, these results suggest that BL Lacs and FSRQs are similar objects residing in the same dense environment typical of galaxy groups, despite their different spectral energy distributions, power, and accretion rates. We find no difference in the typical bias and hosting halo mass between Fermi blazars and radio-loud active galactic nuclei (AGNs), supporting the unification scheme simply equating radio-loud objects with misaligned blazar counterparts. This similarity in terms of the typical environment they preferentially live in, suggests that blazars tend to occupy the center of DMHs, as already pointed out for radio-loud AGNs. This implies, in light of several projects looking for the ?-ray emission from DM annihilation in galaxy clusters, a strong contamination from blazars to the expected signal from DM annihilation.

  14. President Obama Names Scientists Bard and Sessler as Enrico Fermi Award

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

    Recipients | Department of Energy Bard and Sessler as Enrico Fermi Award Recipients President Obama Names Scientists Bard and Sessler as Enrico Fermi Award Recipients January 13, 2014 - 1:43pm Addthis NEWS MEDIA CONTACT (202)586-4940 WASHINGTON - President Obama has named Dr. Allen J. Bard and Dr. Andrew Sessler as recipients of the Enrico Fermi Award, one of the government's oldest and most prestigious awards for scientific achievement. The Presidential award carries an honorarium of

  15. President Obama Names Scientists Pellegrini and Shank as 2014 Enrico Fermi

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

    Award Recipients | Department of Energy Names Scientists Pellegrini and Shank as 2014 Enrico Fermi Award Recipients President Obama Names Scientists Pellegrini and Shank as 2014 Enrico Fermi Award Recipients June 8, 2015 - 3:30pm Addthis News Media Contact (202) 586-4940 newmedia@hq.doe.gov WASHINGTON - President Obama has named Dr. Claudio Pellegrini and Dr. Charles V. (Chuck) Shank as recipients of the Enrico Fermi Award, one of the government's oldest and most prestigious awards for

  16. Enrico Fermi and the First Self-Sustaining Nuclear Chain Reaction

    Office of Scientific and Technical Information (OSTI)

    Enrico Fermi and the First Self-Sustaining Nuclear Chain Reaction Resources with Additional Information * Fermi Honored * Atoms for Peace * Centennial of Birth * Stamp Patents * Audio/Video Clips * Selected by NSTA for SciLinks "The President of the United States of America ... for especially meritorious contributions to the development, use, or control of atomic energy, grant[s] an award of merit to Enrico Fermi for his contributions to basic neutron physics and the achievement of the

  17. CONSTRAINING THE HIGH-ENERGY EMISSION FROM GAMMA-RAY BURSTS WITH FERMI

    SciTech Connect (OSTI)

    Ackermann, M. [Deutsches Elektronen Synchrotron DESY, D-15738 Zeuthen (Germany); Ajello, M.; Bechtol, K.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bottacini, E.; Buehler, R.; Cameron, R. A.; Charles, E. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Baldini, L.; Bellazzini, R. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Baring, M. G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Bonamente, E.; Cecchi, C. [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy); Bouvier, A. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Brigida, M. [Dipartimento di Fisica 'M. Merlin' dell'Universita e del Politecnico di Bari, I-70126 Bari (Italy); Buson, S. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Caliandro, G. A., E-mail: jchiang@slac.stanford.edu, E-mail: kocevski@slac.stanford.edu, E-mail: moretti@particle.kth.se, E-mail: connauv@uah.edu, E-mail: valerie@nasa.gov, E-mail: michael.briggs@nasa.gov [Institut de Ciencies de l'Espai (IEEE-CSIC), Campus UAB, E-08193 Barcelona (Spain); Collaboration: Fermi Large Area Telescope Team; Fermi Gamma-ray Burst Monitor Team; and others

    2012-08-01

    We examine 288 gamma-ray bursts (GRBs) detected by the Fermi Gamma-ray Space Telescope's Gamma-ray Burst Monitor (GBM) that fell within the field of view of Fermi's Large Area Telescope (LAT) during the first 2.5 years of observations, which showed no evidence for emission above 100 MeV. We report the photon flux upper limits in the 0.1-10 GeV range during the prompt emission phase as well as for fixed 30 s and 100 s integrations starting from the trigger time for each burst. We compare these limits with the fluxes that would be expected from extrapolations of spectral fits presented in the first GBM spectral catalog and infer that roughly half of the GBM-detected bursts either require spectral breaks between the GBM and LAT energy bands or have intrinsically steeper spectra above the peak of the {nu}F{sub {nu}} spectra (E{sub pk}). In order to distinguish between these two scenarios, we perform joint GBM and LAT spectral fits to the 30 brightest GBM-detected bursts and find that a majority of these bursts are indeed softer above E{sub pk} than would be inferred from fitting the GBM data alone. Approximately 20% of this spectroscopic subsample show statistically significant evidence for a cutoff in their high-energy spectra, which if assumed to be due to {gamma}{gamma} attenuation, places limits on the maximum Lorentz factor associated with the relativistic outflow producing this emission. All of these latter bursts have maximum Lorentz factor estimates that are well below the minimum Lorentz factors calculated for LAT-detected GRBs, revealing a wide distribution in the bulk Lorentz factor of GRB outflows and indicating that LAT-detected bursts may represent the high end of this distribution.

  18. Fermi-LAT Observation of Supernova Remnant S147 (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    Fermi-LAT Observation of Supernova Remnant S147 Citation Details In-Document Search Title: ... Subject: 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 71 CLASSICAL AND QUANTUM ...

  19. "Doing business with Argonne and Fermi national labs" - Aug. 21, 2013 |

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

    Argonne National Laboratory "Doing business with Argonne and Fermi national labs" - Aug. 21, 2013 Share Topic Operations Procurement Technology transfer

  20. Anomalous Fermi-Surface Dependent Pairing in a Self-Doped High...

    Office of Scientific and Technical Information (OSTI)

    Subject: 36 MATERIALS SCIENCE; FERMI LEVEL; HIGH-TC SUPERCONDUCTORS; VALENCE; BARIUM OXIDES; CALCIUM OXIDES; COPPER OXIDES; BARIUM FLUORIDES; CALCIUM FLUORIDES; COPPER FLUORIDES; ...

  1. Fermi National Accelerator Laboratory | U.S. DOE Office of Science...

    Office of Science (SC) Website

    LP Home About Laboratory Appraisal Process FY 2015 Report Cards FY 2014 Report Cards FY ... FY 2015 SC Laboratory Performance Report Cards Fermi National Accelerator Laboratory Print ...

  2. Fermi National Accelerator Laboratory | U.S. DOE Office of Science...

    Office of Science (SC) Website

    Fermi National Accelerator Laboratory Laboratory Policy (LP) LP Home About Laboratory Appraisal Process FY 2015 Report Cards FY 2014 Report Cards FY 2013 Report Cards Report Card ...

  3. Detroit Edison's Fermi 1 - Preparation for Reactor Removal

    SciTech Connect (OSTI)

    Swindle, Danny [Sargent and Lundy Engineers, LLC, 55 E. Monroe Street, Chicago, IL 60603 (United States)

    2008-01-15

    This paper is intended to provide information about the ongoing decommissioning tasks at Detroit Edison's Fermi 1 plant, and in particular, the work being performed to prepare the reactor for removal and disposal. In 1972 Fermi 1 was shutdown and the fuel returned to the Atomic Energy Commission. By the end of 1975, a retirement plan was prepared, the bulk sodium removed, and the plant placed in a safe store condition. The plant systems were left isolated with the sodium containing systems inert with carbon dioxide in an attempt to form a carbonate layer, thus passivating the underlying reactive sodium. In 1996, Detroit Edison determined to evaluate the condition of the plant and to make recommendations in relation to the Fermi 1 future plans. At the end of 1997 approval was obtained to remove the bulk asbestos and residual alkali-metals (i.e., sodium and sodium potassium (NaK)). In 2000, full nuclear decommissioning of the plant was approved. To date, the bulk asbestos insulation has been removed, and the only NaK remaining is located in six capillary instrument tubes. The remaining sodium is contained within the reactor, two of the three primary loops, and miscellaneous removed pipes and equipment to be processed. The preferred method for removing or reacting sodium at Fermi 1 is by injecting superheated steam into a heated, nitrogen inert system. The byproducts of this reaction are caustic sodium hydroxide, hydrogen gas, and heat. The decision was made to separate the three primary loops from the reactor for better control prior to processing each loop and the reactor separately. The first loop has already been processed. The main focus is now to process the reactor to allow removal and disposal of the Class C waste prior to the anticipated June 2008 closure of the Barnwell radioactive waste disposal facility located in South Carolina. Lessons learnt are summarized and concern: the realistic schedule and adherence to the schedule, time estimates, personnel accountability, back up or fill in work, work packages, condensation control, radiological contamination control, and organization of the waste stream.

  4. U.S. Department of Energy Fermi National Accelerator Laboratory

    Broader source: Energy.gov [DOE]

    The U.S. Department of Energy's (DOE's) Fermi National Accelerator Laboratory (Fermilab) has replaced old equipment and reduced energy consumption through a partnership with its electric utility, Commonwealth Edison. Fermilab upgraded the centralized cooling system and separated the system into two segments — a "comfort system" to cool the employee office space and a "process system" for the equipment and accelerators. Backup cooling capacity is provided and cooling can be shifted between the process and comfort systems when necessary. The new 4500-ton cooling system is expected to use 40% less energy and is free of ozone-depleting chlorofluorocarbons (CFCs).

  5. Dependence of Kambersky damping on Fermi level and spin orientation

    SciTech Connect (OSTI)

    Qu, T.; Victora, R. H.

    2014-05-07

    Kambersky damping represents the loss of magnetic energy from the electrons to the lattice through the spin orbit interaction. It is demonstrated that, for bcc Fe-based transition metal alloys, the logarithm of the energy loss is proportional to the density of states at the Fermi level. Both inter and intraband damping are calculated for spins at arbitrary angle to the previously examined [001] direction. Although the easy axis 〈100〉 shows isotropic relaxation and achieves the minimum damping value of 0.002, other directions, such as 〈110〉, show substantial anisotropic damping.

  6. Dark matter annihilation and the PAMELA, FERMI, and ATIC anomalies

    SciTech Connect (OSTI)

    El Zant, A. A.; Okada, H.; Khalil, S.

    2010-06-15

    If dark matter annihilation accounts for the tantalizing excess of cosmic ray electron/positrons, as reported by the PAMELA, ATIC, HESS, and FERMI observatories, then the implied annihilation cross section must be relatively large. This results, in the context of standard cosmological models, in very small relic dark matter abundances that are incompatible with astrophysical observations. We explore possible resolutions to this apparent conflict in terms of nonstandard cosmological scenarios; plausibly allowing for large cross sections, while maintaining relic abundances in accord with current observations.

  7. Implication of Tsallis entropy in the ThomasFermi model for self-gravitating fermions

    SciTech Connect (OSTI)

    Ourabah, Kamel; Tribeche, Mouloud

    2014-03-15

    The ThomasFermi approach for self-gravitating fermions is revisited within the theoretical framework of the q-statistics. Starting from the q-deformation of the FermiDirac distribution function, a generalized ThomasFermi equation is derived. It is shown that the Tsallis entropy preserves a scaling property of this equation. The q-statistical approach to Jeans instability in a system of self-gravitating fermions is also addressed. The dependence of the Jeans wavenumber (or the Jeans length) on the parameter q is traced. It is found that the q-statistics makes the Fermionic system unstable at scales shorter than the standard Jeans length. -- Highlights: ThomasFermi approach for self-gravitating fermions. A generalized ThomasFermi equation is derived. Nonextensivity preserves a scaling property of this equation. Nonextensive approach to Jeans instability of self-gravitating fermions. It is found that nonextensivity makes the Fermionic system unstable at shorter scales.

  8. SLAC All Access: Fermi Gamma-ray Space Telescope

    ScienceCinema (OSTI)

    Romani, Roger

    2014-06-24

    Three hundred and fifty miles overhead, the Fermi Gamma-ray Space Telescope silently glides through space. From this serene vantage point, the satellite's instruments watch the fiercest processes in the universe unfold. Pulsars spin up to 700 times a second, sweeping powerful beams of gamma-ray light through the cosmos. The hyperactive cores of distant galaxies spew bright jets of plasma. Far beyond, something mysterious explodes with unfathomable power, sending energy waves crashing through the universe. Stanford professor and KIPAC member Roger W. Romani talks about this orbiting telescope, the most advanced ever to view the sky in gamma rays, a form of light at the highest end of the energy spectrum that's created in the hottest regions of the universe.

  9. Environmental Survey preliminary report, Fermi National Accelerator Laboratory, Batavia, Illinois

    SciTech Connect (OSTI)

    Not Available

    1988-10-01

    This report presents the preliminary findings from the first phase of the Environmental Survey of the US Department of Energy (DOE) Fermi National Accelerator Laboratory (Fermilab), conducted September 14 through 25, 1987. The Survey is being conducted by an interdisciplinary team of environmental specialists led and managed by the Office of Environment, Safety and Health's Office of Environmental Audit. Individual participants for the Survey team are being supplied by a private contractor. The objective of the Survey is to identify environmental problems and areas of environmental risk associated with Fermilab. The Survey covers all environmental media and all areas of environmental regulation. It is being performed in accordance with the DOE Environmental Survey Manual. This phase of the Survey involves the review of existing site environmental data, observations of the operations performed at Fermilab, and interviews with site personnel. 110 refs., 26 figs., 41 tabs.

  10. Odd-frequency density waves: Non-Fermi-liquid metals with an order

    Office of Scientific and Technical Information (OSTI)

    parameter (Journal Article) | SciTech Connect Odd-frequency density waves: Non-Fermi-liquid metals with an order parameter Citation Details In-Document Search Title: Odd-frequency density waves: Non-Fermi-liquid metals with an order parameter We consider states with a charge- or spin-density wave order parameter which is odd in frequency so that the order parameter vanishes at zero frequency and there is a conventional Fermi surface. Such states break translational symmetry and, therefore,

  11. President Obama Welcomes 2013 Fermi Award Winners to the White House |

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

    Department of Energy Welcomes 2013 Fermi Award Winners to the White House President Obama Welcomes 2013 Fermi Award Winners to the White House February 3, 2014 - 6:24pm Addthis Energy Secretary Ernest Moniz presents the 2013 Enrico Fermi Awards to Dr. Allen J. Bard and Dr. Andrew Sessler in a ceremony at the U.S. Department of Energy in Washington, D.C., on February 3, 2014. Fae Jencks Confidential Assistant, White House Office of Science & Technology Policy Editor's note: This article

  12. Secretary Chu Names 2009 Enrico Fermi Award Winners | Department of Energy

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

    Names 2009 Enrico Fermi Award Winners Secretary Chu Names 2009 Enrico Fermi Award Winners September 17, 2009 - 12:00am Addthis WASHINGTON, DC - US Energy Secretary Steven Chu has named Dr. John Bannister Goodenough and Dr. Siegfried S. Hecker as the winners of the Enrico Fermi Award, one of the most prestigious science and technology awards awarded by the U.S. Government. The Presidential award carries an honorarium of $375,000, which will be shared equally, and a gold medal. The award is

  13. THE FERMI GBM GAMMA-RAY BURST CATALOG: THE FIRST TWO YEARS

    SciTech Connect (OSTI)

    Paciesas, William S.; Bhat, P. N.; Briggs, Michael S.; Burgess, J. Michael; Chaplin, Vandiver; Connaughton, Valerie; Goldstein, Adam; Guiriec, Sylvain; Meegan, Charles A.; Van der Horst, Alexander J.; Von Kienlin, Andreas; Diehl, Roland; Foley, Suzanne; Greiner, Jochen; Gruber, David; Bissaldi, Elisabetta; Fishman, Gerald J.; Gibby, Melissa; Giles, Misty; and others

    2012-03-01

    The Fermi Gamma-ray Burst Monitor (GBM) is designed to enhance the scientific return from Fermi in studying gamma-ray bursts (GRBs). In its first two years of operation GBM triggered on 491 GRBs. We summarize the criteria used for triggering and quantify the general characteristics of the triggered GRBs, including their locations, durations, peak flux, and fluence. This catalog is an official product of the Fermi GBM science team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center.

  14. Anomalous Fermi-Surface Dependent Pairing in a Self-Doped

    Office of Scientific and Technical Information (OSTI)

    High-TcSuperconductor (Journal Article) | SciTech Connect Anomalous Fermi-Surface Dependent Pairing in a Self-Doped High-TcSuperconductor Citation Details In-Document Search Title: Anomalous Fermi-Surface Dependent Pairing in a Self-Doped High-TcSuperconductor We report the discovery of a self-doped multilayer high Tcsuperconductor Ba2Ca3Cu4O8F2 (F0234) which contains distinctly differentsuperconducting gap magnitudes along its two Fermi-surface sheets. Whileformal valence counting would

  15. GRB 110709A, 111117A, AND 120107A: FAINT HIGH-ENERGY GAMMA-RAY PHOTON EMISSION FROM FERMI-LAT OBSERVATIONS AND DEMOGRAPHIC IMPLICATIONS

    SciTech Connect (OSTI)

    Zheng Weikang; Akerlof, Carl W.; McKay, Timothy A. [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI 48109 (United States); Pandey, Shashi B. [Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263129 (India); Zhang Binbin [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Zhang Bing [Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States); Sakamoto, Takanori, E-mail: zwk@umich.edu [Center for Research and Exploration in Space Science and Technology (CRESST), NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-09-01

    Launched on 2008 June 11, the Large Area Telescope (LAT) instrument on board the Fermi Gamma-ray Space Telescope has provided a rare opportunity to study high-energy photon emission from gamma-ray bursts (GRBs). Although the majority of such events (27) have been identified by the Fermi-LAT Collaboration, four were uncovered by using more sensitive statistical techniques. In this paper, we continue our earlier work by finding three more GRBs associated with high-energy photon emission, GRB 110709A, 111117A, and 120107A. To systematize our matched filter approach, a pipeline has been developed to identify these objects in nearly real time. GRB 120107A is the first product of this analysis procedure. Despite the reduced threshold for identification, the number of GRB events has not increased significantly. This relative dearth of events with low photon number prompted a study of the apparent photon number distribution. We find an extremely good fit to a simple power law with an exponent of -1.8 {+-} 0.3 for the differential distribution. As might be expected, there is a substantial correlation between the number of lower energy photons detected by the Gamma-ray Burst Monitor (GBM) and the number observed by LAT. Thus, high-energy photon emission is associated with some but not all of the brighter GBM events. Deeper studies of the properties of the small population of high-energy emitting bursts may eventually yield a better understanding of these entire phenomena.

  16. Formation of Gapless Fermi Arcs and Fingerprints of Order in the Pseudogap State of Cuprate Superconductors

    SciTech Connect (OSTI)

    Kondo, Takeshi; Palczewski, Ari; Hamaya, Yoichiro; Takeuchi, Tsunehiro; Wen, J. S.; Xu, Z. J.; Gu, Genda; Kaminski, Adam

    2013-10-08

    We use angle-resolved photoemission spectroscopy and a new quantitative approach based on the partial density of states to study properties of seemingly disconnected portions of the Fermi surface (FS) that are present in the pseudogap state of cuprates called Fermi arcs. We find that the normal state FS collapses very abruptly into Fermi arcs at the pseudogap temperature (T*). Surprisingly, the length of the Fermi arcs remains constant over an extended temperature range between (T*) and Tpair, consistent with the presence of an ordered state below T*. These arcs collapse again at the temperature below which pair formation occurs (Tpair) either to a point or a very short arc, whose length is limited by our experimental resolution. The tips of the arcs span between points defining a set of wave vectors in momentum space, which are the fingerprints of the ordered state that causes the pseudogap.

  17. Formation of Gapless Fermi Arcs and Fingerprints of Order in the Pseudogap State of Cuprate Superconductors

    SciTech Connect (OSTI)

    Kondo, Takeshi; Palczewski, Ari D.; Hamaya, Yoichiro; Takeuchi, Tsunehiro; Wen, J. S.; Gu, Genda; Kaminski, Adam

    2013-10-11

    We use angle-resolved photoemission spectroscopy and a new quantitative approach based on the partial density of states to study properties of seemingly disconnected portions of the Fermi surface (FS) that are present in the pseudogap state of cuprates called Fermi arcs. We find that the normal state FS collapses very abruptly into Fermi arcs at the pseudogap temperature (T?). Surprisingly, the length of the Fermi arcs remains constant over an extended temperature range between T? and Tpair, consistent with the presence of an ordered state below T?. These arcs collapse again at the temperature below which pair formation occurs (Tpair) either to a point or a very short arc, whose length is limited by our experimental resolution. The tips of the arcs span between points defining a set of wave vectors in momentum space, which are the fingerprints of the ordered state that causes the pseudogap.

  18. Pulsed Gamma-Rays From PSR J2021 3651 with the Fermi Large Area...

    Office of Scientific and Technical Information (OSTI)

    Pulsed Gamma-Rays From PSR J2021 3651 with the Fermi Large Area Telescope Citation Details ... Language: English Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 72 PHYSICS ...

  19. Estimating the energy of stitching together the Maxwell and Fermi neutron spectra

    SciTech Connect (OSTI)

    Ionov, V. S. Marin, S. V.

    2014-12-15

    The energy of stitching together the Maxwell and Fermi spectra is estimated on the basis of experimental data and the results of calculations carried out using the MCU-RFFI and MCU-5 codes.

  20. U.S. Department of Energy, Secretary Chu Names 2009 Enrico Fermi...

    Office of Scientific and Technical Information (OSTI)

    John Bannister Goodenough and Dr. Siegfried S. Hecker as the winners of the Enrico Fermi Award, one of the most prestigious science and technology awards awarded by the U.S. ...

  1. Fermi-LAT Detection of a Break in the Gamma-Ray Spectrum of the...

    Office of Scientific and Technical Information (OSTI)

    in the Gamma-Ray Spectrum of the Supernova Remnant Cassiopeia A Citation Details In-Document Search Title: Fermi-LAT Detection of a Break in the Gamma-Ray Spectrum of the Supernova ...

  2. Fermi-LAT Observation of Supernova Remnant S147 (Journal Article...

    Office of Scientific and Technical Information (OSTI)

    We present an analysis of gamma-ray data obtained with the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope in the region around SNR S147 (G180.0-1.7). A ...

  3. Fermi Large Area Telescope Observation of a Gamma-Ray Source...

    Office of Scientific and Technical Information (OSTI)

    at the Position of Eta Carinae Citation Details In-Document Search Title: Fermi Large Area Telescope Observation of a Gamma-Ray Source at the Position of Eta Carinae Authors: ...

  4. Fermi Large Area Telescope Observation of a Gamma-Ray Source...

    Office of Scientific and Technical Information (OSTI)

    at the Position of Eta Carinae Citation Details In-Document Search Title: Fermi Large Area Telescope Observation of a Gamma-Ray Source at the Position of Eta Carinae You are ...

  5. Experiences with string matching on the Fermi Architecture

    SciTech Connect (OSTI)

    Tumeo, Antonino; Secchi, Simone; Villa, Oreste

    2011-02-25

    String matching is at the core of many real-world applications, such as security, bioinformatic, data mining. All these applications requires the ability to match always growing data sets against large dictionaries effectively, fastly and possibly in real time. Unfortunately, string matching is a computationally intensive procedure which poses significant challenges on current software and hardware implementations. Graphic Processing Units (GPU) have become an interesting target for such high-throughput applications, but the algorithms and the data structures need to be redesigned to be parallelized and adapted to the underlining hardware, coping with the limitations imposed by these architectures. In this paper we present an efficient implementation of the Aho-Corasick string matching algorithm on GPU, showing how we progressively redesigned the algorithm and the data structures to fit on the architecture. We then evaluate the implementation on single and multiple Tesla C2050 (T20 ``Fermi'' based) boards, comparing them to the previous Tesla C1060 (T10 based) solutions and equivalent multicore implementations on x86 CPUs. We discuss the various tradeoffs of the different architectures.

  6. Fermi 2: Independent safety assessment of refueling outage

    SciTech Connect (OSTI)

    Arora, H.O. [Detroit Edison, MI (United States)

    1994-12-31

    Industry experience and studies conducted by the U.S. Nuclear Regulatory Commission (NRC) have shown that plants are susceptible to a variety of events that can challenge safety during shutdowns. While these events have neither posed nor indicated an undue risk to public health and safety, they do serve to underscore the importance of effective outage planning and control. The NUMARC 91-06 guidelines suggest that proper planning and execution of outage activities can reduce the likelihood and consequences of events, which ultimately enhances safety during shutdown. The Fermi 2, Independent Safety Engineering Group (ISEG) is charged with the independent safety review of the refueling outage plan and its implementation. The ISEG is responsible for performing a detailed and critical review of proposed outage plan prior to the start of the outage, maintaining surveillance of the adequacy and consistency of the {open_quotes}defense-in-depth{close_quotes} provided during the outage, reviewing the outage plan changes for potential vulnerabilities that could affect safety functions, and investigating selected events that emerge during the course of the outage.

  7. Towards a supersymmetric description of the Fermi Galactic center excess

    SciTech Connect (OSTI)

    Cahill-Rowley, M.; Gainer, J. S.; Hewett, J. L.; Rizzo, T. G.

    2015-02-10

    We attempt to build a model that describes the Fermi galactic gamma-ray excess (FGCE) within a UV-complete Supersymmetric framework; we find this to be highly non-trivial. At the very least a successful Supersymmetric explanation must have several important ingredients in order to fit the data and satisfy other theoretical and experimental constraints. Under the assumption that a single annihilation mediator is responsible for both the observed relic density as well as the FGCE, we show that the requirements are not easily satisfied in many TeV-scale SUSY models, but can be met with some model building effort in the general NMSSM with ~ 10 parameters beyond the MSSM. We find that the data selects a particular region of the parameter space with a mostly singlino lightest Supersymmetric particle and a relatively light CP-odd Higgs boson that acts as the mediator for dark matter annihilation. We study the predictions for various observables within this parameter space, and find that searches for this light CP-odd state at the LHC, as well as searches for the direct detection of dark matter, are likely to be quite challenging. It is possible that a signature could be observed in the flavor sector; however, indirect detection remains the best probe of this scenario.

  8. Towards a supersymmetric description of the Fermi Galactic center excess

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

    Cahill-Rowley, M.; Gainer, J. S.; Hewett, J. L.; Rizzo, T. G.

    2015-02-10

    We attempt to build a model that describes the Fermi galactic gamma-ray excess (FGCE) within a UV-complete Supersymmetric framework; we find this to be highly non-trivial. At the very least a successful Supersymmetric explanation must have several important ingredients in order to fit the data and satisfy other theoretical and experimental constraints. Under the assumption that a single annihilation mediator is responsible for both the observed relic density as well as the FGCE, we show that the requirements are not easily satisfied in many TeV-scale SUSY models, but can be met with some model building effort in the general NMSSMmore » with ~ 10 parameters beyond the MSSM. We find that the data selects a particular region of the parameter space with a mostly singlino lightest Supersymmetric particle and a relatively light CP-odd Higgs boson that acts as the mediator for dark matter annihilation. We study the predictions for various observables within this parameter space, and find that searches for this light CP-odd state at the LHC, as well as searches for the direct detection of dark matter, are likely to be quite challenging. It is possible that a signature could be observed in the flavor sector; however, indirect detection remains the best probe of this scenario.« less

  9. Kondo effect and non-Fermi-liquid behavior in Dirac and Weyl semimetals

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | DOE PAGES Publisher's Accepted Manuscript: Kondo effect and non-Fermi-liquid behavior in Dirac and Weyl semimetals This content will become publicly available on July 7, 2016 Title: Kondo effect and non-Fermi-liquid behavior in Dirac and Weyl semimetals Authors: Principi, Alessandro ; Vignale, Giovanni ; Rossi, E. Publication Date: 2015-07-08 OSTI Identifier: 1198627 Grant/Contract Number: FG02-05ER46203 Type: Publisher's Accepted Manuscript Journal Name: Physical Review

  10. Dual vortex theory of strongly interacting electrons: A non-Fermi liquid

    Office of Scientific and Technical Information (OSTI)

    with a twist (Journal Article) | SciTech Connect Dual vortex theory of strongly interacting electrons: A non-Fermi liquid with a twist Citation Details In-Document Search Title: Dual vortex theory of strongly interacting electrons: A non-Fermi liquid with a twist As discovered in the quantum Hall effect, a very effective way for strongly repulsive electrons to minimize their potential energy is to aquire nonzero relative angular momentum. We pursue this mechanism for interacting

  11. Fermi National Accelerator Laboratory FERMILAB-Conf-95/276-E

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

    Fermi National Accelerator Laboratory FERMILAB-Conf-95/276-E CDF and D0 Observation of the Top Quark S.B. Kim Presented for the CDF and D0 Collaborations Fermi National Accelerator Laboratory P.O. Box 500, Batavia, Illinois 60510 Randall Laboratory University of Michigan Ann Arbor, Michigan 48109 August 1995 Published Proceedings from the 15th International Conference on Physics in Collision, Cracow, Poland, June 8-10, 1995 Operated by Universities Research Association Inc. under Contract No.

  12. Fermi Energy Tuning with Light to Control Doping Profiles During Epitaxy;

    Office of Scientific and Technical Information (OSTI)

    Article No. 182105 (Journal Article) | SciTech Connect Fermi Energy Tuning with Light to Control Doping Profiles During Epitaxy; Article No. 182105 Citation Details In-Document Search Title: Fermi Energy Tuning with Light to Control Doping Profiles During Epitaxy; Article No. 182105 Authors: Sanders, Charlotte E. ; Beaton, Daniel A. ; Reedy, Robert C. ; Alberi, Kristin Publication Date: 2015-05-04 OSTI Identifier: 1220719 Report Number(s): NREL/JA-5K00-64047 Resource Type: Journal Article

  13. Iltt: Fermi National Accelerator Laboratory FERMILAB-Pub-75/44-THY

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

    Iltt: Fermi National Accelerator Laboratory FERMILAB-Pub-75/44-THY June 1975 Weak Interaction Models with New Quarks and Right-Handed Currents" F.A. WILCZEK and A. ZEE t Fermi National Accelerator Laboratory,*Batavia, Illinois 60510 and Joseph Henry Laboratories Princeton University, Princeton, New Jersey 08540 and R. L. KINGSLEY and S. B. TREIMAN Joseph Henry Laboratories Princeton University, Princeton, New Jersey 08540 ABSTRACT We discuss various weak interaction issues for a general

  14. Kondo effect and non-Fermi-liquid behavior in Dirac and Weyl semimetals

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Kondo effect and non-Fermi-liquid behavior in Dirac and Weyl semimetals Citation Details In-Document Search This content will become publicly available on July 7, 2016 Title: Kondo effect and non-Fermi-liquid behavior in Dirac and Weyl semimetals Authors: Principi, Alessandro ; Vignale, Giovanni ; Rossi, E. Publication Date: 2015-07-08 OSTI Identifier: 1198627 Grant/Contract Number: FG02-05ER46203 Type: Publisher's Accepted Manuscript Journal Name:

  15. The Search of Axion-Like-Particles With Fermi and Cherenkov Telescopes

    Office of Scientific and Technical Information (OSTI)

    (Conference) | SciTech Connect SciTech Connect Search Results Conference: The Search of Axion-Like-Particles With Fermi and Cherenkov Telescopes Citation Details In-Document Search Title: The Search of Axion-Like-Particles With Fermi and Cherenkov Telescopes Authors: Sanchez-Conde, Miguel A. ; /IAC, La Laguna ; Paneque, David ; /KIPAC, Menlo Park /SLAC ; Bloom, Elliott D. ; /KIPAC, Menlo Park /SLAC ; Prada, Francisco ; /IAA, Granada ; Dominguez, Alberto ; /CNA, Seville /IAA, Granada

  16. A Method to Analyze the Diffuse Gamma-Ray Emission with the Fermi Large

    Office of Scientific and Technical Information (OSTI)

    Area Telescope (Journal Article) | SciTech Connect A Method to Analyze the Diffuse Gamma-Ray Emission with the Fermi Large Area Telescope Citation Details In-Document Search Title: A Method to Analyze the Diffuse Gamma-Ray Emission with the Fermi Large Area Telescope Authors: Ackermann, Markus ; /KIPAC, Menlo Park /SLAC ; Johannesson, Gudlaugur ; /KIPAC, Menlo Park /SLAC ; Digel, Seth ; /KIPAC, Menlo Park /SLAC ; Moskalenko, Igor V. ; /KIPAC, Menlo Park /SLAC ; Porter, Troy ; /UC, Santa Cruz

  17. Towards a Holographic Marginal Fermi Liquid (Journal Article) | SciTech

    Office of Scientific and Technical Information (OSTI)

    Connect Towards a Holographic Marginal Fermi Liquid Citation Details In-Document Search Title: Towards a Holographic Marginal Fermi Liquid We present an infinite class of 2+1 dimensional field theories which, after coupling to semi-holographic fermions, exhibit strange metallic behavior in a suitable large N limit. These theories describe lattices of hypermultiplet defects interacting with parity-preserving supersymmetric Chern-Simons theories with U(N) x U(N) gauge groups at levels {+-}k.

  18. Towards a holographic marginal Fermi liquid (Journal Article) | SciTech

    Office of Scientific and Technical Information (OSTI)

    Connect Towards a holographic marginal Fermi liquid Citation Details In-Document Search Title: Towards a holographic marginal Fermi liquid Authors: Jensen, Kristan ; Kachru, Shamit ; Karch, Andreas ; Polchinski, Joseph ; Silverstein, Eva Publication Date: 2011-12-02 OSTI Identifier: 1098349 Type: Publisher's Accepted Manuscript Journal Name: Physical Review D Additional Journal Information: Journal Volume: 84; Journal Issue: 12; Journal ID: ISSN 1550-7998 Publisher: American Physical Society

  19. Van der Waals Metal-Semiconductor Junction: Weak Fermi Level Pinning

    Office of Scientific and Technical Information (OSTI)

    Enables Effective Tuning of Schottky Barrier (Journal Article) | SciTech Connect Van der Waals Metal-Semiconductor Junction: Weak Fermi Level Pinning Enables Effective Tuning of Schottky Barrier Citation Details In-Document Search This content will become publicly available on April 1, 2017 Title: Van der Waals Metal-Semiconductor Junction: Weak Fermi Level Pinning Enables Effective Tuning of Schottky Barrier Two-dimensional (2D) semiconductors have shown great potential for electronic and

  20. Modeling High-Energy Gamma-Rays from the Fermi Bubbles - Oral Presentation

    SciTech Connect (OSTI)

    Splettstoesser, Megan

    2015-08-25

    In 2010, the Fermi Bubbles were discovered at the galactic center of the Milky Way. These giant gamma-ray structures, extending 50 degrees in galactic latitude and 20-30 degrees in galactic longitude, were not predicted. We wish to develop a model for the gamma-ray emission of the Fermi Bubbles. To do so, we assume that second order Fermi acceleration is responsible for the high-energy emission of the bubbles. Second order Fermi acceleration requires charged particles and irregular magnetic fields—both of which are present in the disk of the Milky Way galaxy. I use the assumption of second order Fermi acceleration in the transport equation, which describes the diffusion of particles. By solving the steady-state case of the transport equation, I compute the proton spectrum due to Fermi second order acceleration and compare this analytical solution to a numerical solution provided by Dr. P. Mertsch. Analytical solutions to the transport equation are taken from Becker, Le, & Dermer and are used to further test the numerical solution. I find that the numerical solution converges to the analytical solution in all cases. Thus, we know the numerical solution accurately calculates the proton spectrum. The gamma-ray spectrum follows the proton spectrum, and will be computed in the future.

  1. Secrets of superconductivity revealed

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

    Secrets of superconductivity revealed Secrets of superconductivity revealed The superconducting material Cerium-Colbalt-Indium5 reveals new secrets about how superconductivity and magnetism can be related. January 3, 2014 Simon Gerber, first author of the publication on the superconducting properties of CeCoIn5 at the Morpheus instrument of the Spallation Neutron Source SINQ in Switzerland. (Photo: Paul Scherrer Institute/Markus Fischer) Simon Gerber, first author of the publication on the

  2. Modeling high-energy gamma-rays from the Fermi Bubbles

    SciTech Connect (OSTI)

    Splettstoesser, Megan

    2015-09-17

    In 2010, the Fermi Bubbles were discovered at the galactic center of the Milky Way. These giant gamma-ray structures, extending 55° in galactic latitude and 20°-30° in galactic longitude, were not predicted. We wish to develop a model for the gamma-ray emission of the Fermi Bubbles. To do so, we assume that second order Fermi acceleration requires charged particles and irregular magnetic fields- both of which are present in the disk of the Milky Way galaxy. By solving the steady-state case of the transport equation, I compute the proton spectrum due to second order Fermi acceleration. I compare the analytical solutions of the proton spectrum to a numerical solution. I find that the numerical solution to the transport equation converges to the analytical solution in all cases. The gamma-ray spectrum due to proton-proton interaction is compared to Fermi Bubble data (from Ackermann et al. 2014), and I find that second order Fermi acceleration is a good fit for the gamma-ray spectrum of the Fermi Bubbles at low energies with an injection source term of S = 1.5 x 10⁻¹⁰ GeV⁻¹cm⁻³yr⁻¹. I find that a non-steady-state solution to the gamma-ray spectrum with an injection source term of S = 2 x 10⁻¹⁰ GeV⁻¹cm⁻³yr⁻¹ matches the bubble data at high energies.

  3. Extending the Fermi-LAT data processing pipeline to the grid

    SciTech Connect (OSTI)

    Zimmer, S.; Arrabito, L.; Glanzman, T.; Johnson, T.; Lavalley, C.; Tsaregorodtsev, A.

    2015-05-12

    The Data Handling Pipeline ("Pipeline") has been developed for the Fermi Gamma-Ray Space Telescope (Fermi) Large Area Telescope (LAT) which launched in June 2008. Since then it has been in use to completely automate the production of data quality monitoring quantities, reconstruction and routine analysis of all data received from the satellite and to deliver science products to the collaboration and the Fermi Science Support Center. Aside from the reconstruction of raw data from the satellite (Level 1), data reprocessing and various event-level analyses are also reasonably heavy loads on the pipeline and computing resources. These other loads, unlike Level 1, can run continuously for weeks or months at a time. Additionally, it receives heavy use in performing production Monte Carlo tasks.

  4. Relativistic equation of state at subnuclear densities in the Thomas-Fermi approximation

    SciTech Connect (OSTI)

    Zhang, Z. W.; Shen, H., E-mail: shennankai@gmail.com [School of Physics, Nankai University, Tianjin 300071 (China)

    2014-06-20

    We study the non-uniform nuclear matter using the self-consistent Thomas-Fermi approximation with a relativistic mean-field model. The non-uniform matter is assumed to be composed of a lattice of heavy nuclei surrounded by dripped nucleons. At each temperature T, proton fraction Y{sub p} , and baryon mass density ? {sub B}, we determine the thermodynamically favored state by minimizing the free energy with respect to the radius of the Wigner-Seitz cell, while the nucleon distribution in the cell can be determined self-consistently in the Thomas-Fermi approximation. A detailed comparison is made between the present results and previous calculations in the Thomas-Fermi approximation with a parameterized nucleon distribution that has been adopted in the widely used Shen equation of state.

  5. Indirect searches for dark matter with the Fermi large area telescope

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

    Albert, Andrea

    2015-03-24

    There is overwhelming evidence that non-baryonic dark matter constitutes ~ 27% of the energy density of the Universe. Weakly Interacting Massive Particles (WIMPs) are promising dark matter candidates that may produce γ rays via annihilation or decay detectable by the Fermi Large Area Telescope (LAT). A detection of WIMPs would also indicate the existence of physics beyond the Standard Model. We present recent results from the two cleanest indirect WIMP searches by the Fermi-LAT Collaboration: searches for γ-ray spectral lines and γ-ray emission associated with Milky Way dwarf spheroidal satellite galaxies.

  6. Distribution of occupation numbers in finite Fermi systems and role of interaction in chaos and thermalization

    SciTech Connect (OSTI)

    Flambaum, V.V.; Izrailev, F.M. [School of Physics, University of New South Wales, Sydney 2052 (Australia)] [School of Physics, University of New South Wales, Sydney 2052 (Australia)

    1997-01-01

    A method is developed for calculation of single-particle occupation numbers in finite Fermi systems of interacting particles. It is more accurate than the canonical distribution method and gives the Fermi-Dirac distribution in the limit of large number of particles. It is shown that statistical effects of the interaction are absorbed by an increase of the effective temperature. Criteria for quantum chaos and statistical equilibrium are considered. All results are confirmed by numerical experiments in the two-body random interaction model. {copyright} {ital 1997} {ital The American Physical Society}

  7. Annealing, lattice disorder and non-Fermi liquid behavior in UCu4Pd

    SciTech Connect (OSTI)

    Booth, C.H.; Scheidt, E.-W.; Killer, U.; Weber, A.; Kehrein, S.

    2002-07-30

    The magnetic and electronic properties of non-Fermi liquid UCu{sub 4Pd} depend on annealing conditions. Local structural changes due to this annealing are reported from UL{sub III}- and Pd K-edge x-ray absorption fine-structure measurements. In particular, annealing decreases the fraction of Pd atoms on nominally Cu 16e sites and the U-Cu pair-distance distribution width. This study provides quantitative information on the amount of disorder in UCu{sub 4Pd} and allows an assessment of its possible importance to the observed non-Fermi liquid behavior.

  8. Fermi National Accelerator Laboratory FERMILAB-Conf-96/099E

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

    it Fermi National Accelerator Laboratory FERMILAB-Conf-96/099E CoK)C,. WoO3P73 -- 3 CDF CDF Top Physics G. F. Tartarelli For the CDF Collaboration Fermi National Accelerator Laboratory P.O. Box 500, Batavia, Illinois 60510 I.N.F.N., Sezione di Milano 1-20133 Milano (MI), Italy MASTER May 1996 Proceedings of XXXIst Recontres de Moriond, Electroweak Interactions and Unified Theories, Les Arcs, France, March 16-23, 1996. Operated by Universities Research Association Inc. under Contract No.

  9. Fermi surface topology and hot spot distribution in the Kondo lattice

    Office of Scientific and Technical Information (OSTI)

    system CeB 6 (Journal Article) | SciTech Connect Fermi surface topology and hot spot distribution in the Kondo lattice system CeB 6 Citation Details In-Document Search This content will become publicly available on September 17, 2016 Title: Fermi surface topology and hot spot distribution in the Kondo lattice system CeB 6 Authors: Neupane, Madhab ; Alidoust, Nasser ; Belopolski, Ilya ; Bian, Guang ; Xu, Su-Yang ; Kim, Dae-Jeong ; Shibayev, Pavel P. ; Sanchez, Daniel S. ; Zheng, Hao ; Chang,

  10. Fermi-LAT Detection of a Break in the Gamma-Ray Spectrum of the Supernova

    Office of Scientific and Technical Information (OSTI)

    Remnant Cassiopeia A (Journal Article) | SciTech Connect Fermi-LAT Detection of a Break in the Gamma-Ray Spectrum of the Supernova Remnant Cassiopeia A Citation Details In-Document Search Title: Fermi-LAT Detection of a Break in the Gamma-Ray Spectrum of the Supernova Remnant Cassiopeia A Authors: Yuan, Y. ; Funk, S. ; Johannesson, G. ; Lande, J. ; Tibaldo, L. ; Uchiyama, Y. ; /Stanford U., HEPL /KIPAC, Menlo Park /SLAC /Iceland U. ; , Publication Date: 2013-11-07 OSTI Identifier: 1104713

  11. Flux and Photon Spectral Index Distributions of Fermi-LAT Blazars and

    Office of Scientific and Technical Information (OSTI)

    Contribution to the Extragalactic Gamma-ray Background (Journal Article) | SciTech Connect Flux and Photon Spectral Index Distributions of Fermi-LAT Blazars and Contribution to the Extragalactic Gamma-ray Background Citation Details In-Document Search Title: Flux and Photon Spectral Index Distributions of Fermi-LAT Blazars and Contribution to the Extragalactic Gamma-ray Background We present a determination of the distributions of gamma-ray flux - the so called LogN-LogS relation - and

  12. Measurement of the Positive Muon Lifetime and Determination of the Fermi

    Office of Scientific and Technical Information (OSTI)

    Constant to Part-per-Million Precision (Journal Article) | SciTech Connect Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant to Part-per-Million Precision Citation Details In-Document Search Title: Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant to Part-per-Million Precision We report a measurement of the positive muon lifetime to a precision of 1.0 ppm; it is the most precise particle lifetime ever measured. The experiment

  13. Spin Polarization and Texture of the Fermi Arcs in the Weyl Fermion

    Office of Scientific and Technical Information (OSTI)

    Semimetal TaAs (Journal Article) | SciTech Connect Spin Polarization and Texture of the Fermi Arcs in the Weyl Fermion Semimetal TaAs Citation Details In-Document Search This content will become publicly available on March 1, 2017 Title: Spin Polarization and Texture of the Fermi Arcs in the Weyl Fermion Semimetal TaAs Authors: Xu, Su-Yang ; Belopolski, Ilya ; Sanchez, Daniel S. ; Neupane, Madhab ; Chang, Guoqing ; Yaji, Koichiro ; Yuan, Zhujun ; Zhang, Chenglong ; Kuroda, Kenta ; Bian,

  14. Neutron Physics. A Revision of I. Halpern's notes on E. Fermi's lectures in 1945

    DOE R&D Accomplishments [OSTI]

    Beckerley, J.G.

    1951-10-16

    In the Fall of 1945 a course in Neutron Physics was given by Professor Fermi as part of the program of the Los Alamos University. The course consisted of thirty lectures most of which were given by Fermi. In his absence R.F. Christy and E. Segre gave several lectures. The present revision is based upon class notes prepared by I. Halpern with some assistance by B.T. Feld and issued first as document LADC 255 and later with wider circulation as MDDC 320.

  15. ORISE: PeerNet® used to support DOE's Office of Science Enrico Fermi

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

    Award selection ORAU PeerNet® used to support DOE's Office of Science Enrico Fermi Award selection Peer review tool provided secure access for evaluating award nominees FOR IMMEDIATE RELEASE Feb. 5, 2014 FY14-08 WASHINGTON, D.C.-ORAU's electronic peer review and evaluation system, PeerNet®, was used to support the selection of recipients for the U.S. Department of Energy's (DOE) Office of Science Enrico Fermi Award, a prestigious award presented by U.S. Secretary of Energy Dr. Ernest Moniz

  16. Indirect searches for dark matter with the Fermi large area telescope

    SciTech Connect (OSTI)

    Albert, Andrea

    2015-03-24

    There is overwhelming evidence that non-baryonic dark matter constitutes ~ 27% of the energy density of the Universe. Weakly Interacting Massive Particles (WIMPs) are promising dark matter candidates that may produce ? rays via annihilation or decay detectable by the Fermi Large Area Telescope (LAT). A detection of WIMPs would also indicate the existence of physics beyond the Standard Model. We present recent results from the two cleanest indirect WIMP searches by the Fermi-LAT Collaboration: searches for ?-ray spectral lines and ?-ray emission associated with Milky Way dwarf spheroidal satellite galaxies.

  17. Fermi surfaces and Phase Stability of Ba(Fe1-xMx))2As2 (M=Co...

    Office of Scientific and Technical Information (OSTI)

    Fermi surfaces and Phase Stability of Ba(Fe1-xMx))2As2 (MCo, Ni, Cu, Zn) Citation Details In-Document Search Title: Fermi surfaces and Phase Stability of Ba(Fe1-xMx))2As2 (MCo,...

  18. Fermi surfaces and phase stability of Ba(Fe1-xMx)2As2 (M = Co...

    Office of Scientific and Technical Information (OSTI)

    Fermi surfaces and phase stability of Ba(Fe1-xMx)2As2 (M Co,Ni,Cu,Zn) Citation Details In-Document Search Title: Fermi surfaces and phase stability of Ba(Fe1-xMx)2As2 (M ...

  19. FERMI RULES OUT THE INVERSE COMPTON/CMB MODEL FOR THE LARGE-SCALE JET X-RAY EMISSION OF 3C 273

    SciTech Connect (OSTI)

    Meyer, Eileen T.; Georganopoulos, Markos

    2014-01-10

    The X-ray emission mechanism in large-scale jets of powerful radio quasars has been a source of debate in recent years, with two competing interpretations: either the X-rays are of synchrotron origin, arising from a different electron energy distribution than that producing the radio to optical synchrotron component, or they are due to inverse Compton scattering of cosmic microwave background photons (IC/CMB) by relativistic electrons in a powerful relativistic jet with bulk Lorentz factor ? ? 10-20. These two models imply radically different conditions in the large-scale jet in terms of jet speed, kinetic power, and maximum energy of the particle acceleration mechanism, with important implications for the impact of the jet on the large-scale environment. A large part of the X-ray origin debate has centered on the well-studied source 3C 273. Here we present new observations from Fermi which put an upper limit on the gamma-ray flux from the large-scale jet of 3C 273 that violates at a confidence greater that 99.9% the flux expected from the IC/CMB X-ray model found by extrapolation of the UV to X-ray spectrum of knot A, thus ruling out the IC/CMB interpretation entirely for this source when combined with previous work. Further, this upper limit from Fermi puts a limit on the Doppler beaming factor of at least ? <9, assuming equipartition fields, and possibly as low as ? <5, assuming no major deceleration of the jet from knots A throughD1.

  20. Fermi-level pinning, charge transfer, and relaxation of spin-momentum locking at metal contacts to topological insulators

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

    Spataru, Catalin D.; Léonard, François

    2014-08-13

    Topological insulators are of interest for many applications in electronics and optoelectronics, but harnessing their unique properties requires detailed understanding and control of charge injection at electrical contacts. Here we present large-scale ab initio calculations of the electronic properties of Au, Ni, Pt, Pd, and graphene contacts to Bi2Se3. We show that regardless of the metal, the Fermi level is located in the conduction band, leading to n-type Ohmic contact to the first quintuplet. Furthermore, we find strong charge transfer and band-bending in the first few quintuplets, with no Schottky barrier for charge injection even when the topoplogical insulator ismore » undoped. Our calculations indicate that Au and graphene leave the spin-momentum locking mostly unaltered, but on the other hand, Ni, Pd, and Pt strongly hybridize with Bi2Se3 and relax spin-momentum locking. In conclusion, our results indicate that judicious choice of the contact metal is essential to reveal the unique surface features of topological insulators.« less

  1. Fermi-LAT Discovery of GeV Gamma-ray Emission from the Young Supernova Remnant Cassiopeia A

    SciTech Connect (OSTI)

    Abdo, A.A.

    2011-08-19

    We report on the first detection of GeV high-energy gamma-ray emission from a young supernova remnant with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope. These observations reveal a source with no discernible spatial extension detected at a significance level of 12.2{sigma} above 500 MeV at a location that is consistent with the position of the remnant of the supernova explosion that occurred around 1680 in the Cassiopeia constellation - Cassiopeia A. The gamma-ray flux and spectral shape of the source are consistent with a scenario in which the gamma-ray emission originates from relativistic particles accelerated in the shell of this remnant. The total content of cosmic rays (electrons and protons) accelerated in Cas A can be estimated as W{sub CR} {approx_equal} (1-4) x 10{sup 49} erg thanks to the well-known density in the remnant assuming that the observed gamma-ray originates in the SNR shell(s). The magnetic field in the radio-emitting plasma can be robustly constrained as B {ge} 0.1 mG, providing new evidence of the magnetic field amplification at the forward shock and the strong field in the shocked ejecta.

  2. Role of fourth-order phase-space moments in collective modes of trapped Fermi gases

    SciTech Connect (OSTI)

    Chiacchiera, Silvia; Lepers, Thomas; Davesne, Dany; Urban, Michael

    2011-10-15

    We study the transition from hydrodynamic to collisionless behavior in collective modes of ultracold trapped Fermi gases. To that end, we solve the Boltzmann equation for the trapped Fermi gas via the moments method. We showed previously that it is necessary to go beyond second-order moments if one wants to reproduce the results of a numerical solution of the Boltzmann equation. Here, we will give the detailed description of the method including fourth-order moments. We apply this method to the case of realistic parameters, and compare the results for the radial quadrupole and scissors modes at unitarity to experimental data obtained by the Innsbruck group. It turns out that the inclusion of fourth-order moments clearly improves the agreement with the experimental data. In particular, the fourth-order moments reduce the effect of collisions and therefore partially compensate the effect of the enhanced in-medium cross section at low temperatures.

  3. Constraints on decaying dark matter from Fermi observations of nearby galaxies and clusters

    SciTech Connect (OSTI)

    Dugger, Leanna; Profumo, Stefano [Department of Astronomy and Department of Physics, University of California Berkeley, 601 Campbell Hall, Berkeley, CA (United States); Jeltema, Tesla E., E-mail: greentee01@gmail.com, E-mail: tesla@ucolick.org, E-mail: profumo@scipp.ucsc.edu [UCO/Lick Observatories, 1156 High St., Santa Cruz, CA 95064 (United States)

    2010-12-01

    We analyze the impact of Fermi gamma-ray observations (primarily non-detections) of selected nearby galaxies, including dwarf spheroidals, and of clusters of galaxies on decaying dark matter models. We show that the fact that galaxy clusters do not shine in gamma rays puts the most stringent limits available to-date on the lifetime of dark matter particles for a wide range of particle masses and decay final states. In particular, our results put strong constraints on the possibility of ascribing to decaying dark matter both the increasing positron fraction reported by PAMELA and the high-energy feature in the electron-positron spectrum measured by Fermi. Observations of nearby dwarf galaxies and of the Andromeda Galaxy (M31) do not provide as strong limits as those from galaxy clusters, while still improving on previous constraints in some cases.

  4. Shot-noise at a Fermi-edge singularity: Non-Markovian dynamics

    SciTech Connect (OSTI)

    Ubbelohde, N.; Maire, N.; Haug, R. J.; Roszak, K.; Hohls, F.; Novotn, T.

    2013-12-04

    For an InAs quantum dot we study the current shot noise at a Fermi-edge singularity in low temperature cross-correlation measurements. In the regime of the interaction effect the strong suppression of noise observed at zero magnetic field and the sequence of enhancement and suppression in magnetic field go beyond a Markovian master equation model. Qualitative and quantitative agreement can however be achieved by a generalized master equation model taking non-Markovian dynamics into account.

  5. Fermi Site Office EA / EIS | U.S. DOE Office of Science (SC)

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

    Fermi Site Office EA / EIS Safety and Security Policy (SSP) SSP Home About Frequently Used Resources NEPA Documents Categorical Exclusion Determinations Environmental Assessments and Environmental Impact Statements Continuity of Operations (COOP) Implementation Plan Contact Information Safety and Security Policy U.S. Department of Energy SC-31/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-6800 F: (301) 903-7047 More Information » Environmental Assessments (EA)

  6. Poisson-Nernst-Planck-Fermi theory for modeling biological ion channels

    SciTech Connect (OSTI)

    Liu, Jinn-Liang; Eisenberg, Bob

    2014-12-14

    A Poisson-Nernst-Planck-Fermi (PNPF) theory is developed for studying ionic transport through biological ion channels. Our goal is to deal with the finite size of particle using a Fermi like distribution without calculating the forces between the particles, because they are both expensive and tricky to compute. We include the steric effect of ions and water molecules with nonuniform sizes and interstitial voids, the correlation effect of crowded ions with different valences, and the screening effect of water molecules in an inhomogeneous aqueous electrolyte. Including the finite volume of water and the voids between particles is an important new part of the theory presented here. Fermi like distributions of all particle species are derived from the volume exclusion of classical particles. Volume exclusion and the resulting saturation phenomena are especially important to describe the binding and permeation mechanisms of ions in a narrow channel pore. The Gibbs free energy of the Fermi distribution reduces to that of a Boltzmann distribution when these effects are not considered. The classical Gibbs entropy is extended to a new entropy form — called Gibbs-Fermi entropy — that describes mixing configurations of all finite size particles and voids in a thermodynamic system where microstates do not have equal probabilities. The PNPF model describes the dynamic flow of ions, water molecules, as well as voids with electric fields and protein charges. The model also provides a quantitative mean-field description of the charge/space competition mechanism of particles within the highly charged and crowded channel pore. The PNPF results are in good accord with experimental currents recorded in a 10{sup 8}-fold range of Ca{sup 2+} concentrations. The results illustrate the anomalous mole fraction effect, a signature of L-type calcium channels. Moreover, numerical results concerning water density, dielectric permittivity, void volume, and steric energy provide useful details to study a variety of physical mechanisms ranging from binding, to permeation, blocking, flexibility, and charge/space competition of the channel.

  7. Installation and commissioning of the new Fermi National Accelerator Laboratory H- Magnetron

    SciTech Connect (OSTI)

    Bollinger, D. S.

    2014-02-15

    The Fermi National Accelerator Laboratory (FNAL) 40 year old Cockcroft-Walton 750 keV injectors with slit aperture magnetron ion sources have been replaced with a circular aperture magnetron, Low Energy Beam Transport, Radio Frequency Quadrupole Accelerator, and Medium Energy Beam Transport, as part of the FNAL Proton Improvement Plan. The injector design is based on a similar system at Brookhaven National Laboratory. The installation, commissioning efforts, and source operations to date will be covered in this paper along with plans for additional changes to the original design to improve reliability by reducing extractor spark rates and arc current duty factor.

  8. Ferromagnetic Kondo lattice CeRuSi{sub 2} with non-Fermi-liquid behavior

    SciTech Connect (OSTI)

    Nikiforov, V. N.; Baran, M.; Irkhin, V. Yu.

    2013-05-15

    The structure, electronic, thermodynamic, and magnetic properties of the CeRuSi{sub 2} Kondo lattice with ferromagnetic ordering characterized by a small moment of the ground state are investigated. Anomalies in the temperature dependences of heat capacity and resistivity (unusual power or logarithmic behavior) observed in the low-temperature range indicate a non-Fermi-liquid behavior. The results are compared with those for other Ce{sub l}Ru{sub n}X{sub m} compounds and anomalous systems based on rare-earth elements and actinides that had been studied earlier.

  9. Disorder-Driven Non-Fermi-Liquid Behavior in Kondo Alloys

    SciTech Connect (OSTI)

    Miranda, E.; Dobrosavljevic, V.; Kotliar, G.

    1997-01-01

    We show how a model of disordered Anderson lattices can account for many non-Fermi-liquid features observed in some Kondo alloys. Because of the exponential nature of the Kondo temperature scale T{sub K}, even moderate disorder leads to a rather broad distribution of Kondo temperatures, inducing strong {ital effective} disorder seen by the conduction electrons. Spins with very low T{sub K}`s remain unquenched and dominate the low-temperature properties.This single underlying mechanism leads to logarithmic divergences in thermodynamic quantities and a linear temperature dependence of the resistivity. {copyright} {ital 1997} {ital The American Physical Society}

  10. Fermi Large Area Telescope Constraints on the Gamma-ray Opacity of the

    Office of Scientific and Technical Information (OSTI)

    Universe (Journal Article) | SciTech Connect Large Area Telescope Constraints on the Gamma-ray Opacity of the Universe Citation Details In-Document Search Title: Fermi Large Area Telescope Constraints on the Gamma-ray Opacity of the Universe Authors: Abdo, A.A. ; /Naval Research Lab, Wash., D.C. /Natl. Acad. Sci. ; Ackermann, M. ; Ajello, M. ; Allafort, A. ; /SLAC /KIPAC, Menlo Park /Stanford U., HEPL /Stanford U., Phys. Dept. ; Atwood, W.B. ; /UC, Santa Cruz ; Baldini, L. ; /INFN, Pisa ;

  11. Fermi Observations of GRB 090510: a Short Hard Gamma-Ray Burst with an

    Office of Scientific and Technical Information (OSTI)

    Additional, Hard Power-Law Component from 10 KeV to GeV Energies (Journal Article) | SciTech Connect Observations of GRB 090510: a Short Hard Gamma-Ray Burst with an Additional, Hard Power-Law Component from 10 KeV to GeV Energies Citation Details In-Document Search Title: Fermi Observations of GRB 090510: a Short Hard Gamma-Ray Burst with an Additional, Hard Power-Law Component from 10 KeV to GeV Energies Authors: Ackermann, M. ; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys.

  12. The influence of pairing correlations on the isospin symmetry breaking corrections of superallowed Fermi beta decays

    SciTech Connect (OSTI)

    Cal Latin-Small-Letter-Dotless-I k, A. E.; Gerceklioglu, M.; Selam, C.

    2013-05-15

    Within the framework of quasi-particle random phase approximation, the isospin breaking correction of superallowed 0{sup +} {yields} 0{sup +} beta decay and unitarity of Cabibbo-Kobayashi-Maskawa mixing matrix have been investigated. The broken isotopic symmetry of nuclear part of Hamiltonian has been restored by Pyatov's method. The isospin symmetry breaking correction with pairing correlations has been compared with the previous results without pairing. The effect of pairing interactions has been examined for nine superallowed Fermi beta decays; their parent nuclei are {sup 26}Al, {sup 34}Cl, {sup 38}K, {sup 42}Sc, {sup 46}V, {sup 50}Mn, {sup 54}Co, {sup 62}Ga, {sup 74}Rb.

  13. Fermi Site Office CX Determinations | U.S. DOE Office of Science (SC)

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

    Additional, Hard Power-Law Component from 10 KeV to GeV Energies (Journal Article) | SciTech Connect Observations of GRB 090510: a Short Hard Gamma-Ray Burst with an Additional, Hard Power-Law Component from 10 KeV to GeV Energies Citation Details In-Document Search Title: Fermi Observations of GRB 090510: a Short Hard Gamma-Ray Burst with an Additional, Hard Power-Law Component from 10 KeV to GeV Energies Authors: Ackermann, M. ; /Stanford U., HEPL /KIPAC, Menlo Park /Stanford U., Phys.

  14. Search for Large Extra Dimensions Based on Observations of Neutron Stars with the Fermi-LAT

    SciTech Connect (OSTI)

    Berenji, Bijan; /Stanford U., Appl. Phys. Dept. /SLAC

    2012-09-19

    Large extra dimensions (LED) have been proposed to account for the apparent weakness of gravitation. These theories also indicate that the postulated massive Kaluza-Klein (KK) gravitons may be produced by nucleon-nucleon bremsstrahlung in the course of core collapse of supernovae. Hannestad and Raffelt have predicted energy spectra of gamma ray emission from the decay of KK gravitons trapped by the gravity of the remnant neutron stars (NS). These and other authors have used EGRET data on NS to obtain stringent limits on LED. Fermi-LAT is observing radio pulsar positions obtained from radio and x-ray catalogs. NS with certain characteristics are unlikely emitter of gamma rays, and emit in radio and perhaps x-rays. This talk will focus on the blind analysis we plan to perform, which has been developed using the 1st 2 months of all sky data and Monte Carlo simulations, to obtain limits on LED based on about 1 year of Fermi-LAT data. Preliminary limits from this analysis using these first 2 months of data will be also be discussed.

  15. Multi-wavelength emission from the Fermi bubbles. I. Stochastic acceleration from background plasma

    SciTech Connect (OSTI)

    Cheng, K. S.; Chernyshov, D. O.; Dogiel, V. A.; Ko, C. M.

    2014-07-20

    We analyze processes of electron acceleration in the Fermi bubbles in order to define parameters and restrictions of the models, which are suggested for the origin of these giant radio and gamma-ray structures. In the case of the leptonic origin of the nonthermal radiation from the bubbles, these electrons should be produced somehow in situ because of the relatively short lifetime of high-energy electrons, which lose their energy by synchrotron and inverse-Compton processes. It has been suggested that electrons in bubbles may be accelerated by shocks produced by tidal disruption of stars accreting onto the central black hole or a process of re-acceleration of electrons ejected by supernova remnants. These processes will be investigated in subsequent papers. In this paper, we focus on in situ stochastic (Fermi) acceleration by a hydromagnetic/supersonic turbulence, in which electrons can be directly accelerated from the background plasma. We showed that the acceleration from the background plasma is able to explain the observed fluxes of radio and gamma-ray emission from the bubbles, but the range of permitted parameters of the model is strongly restricted.

  16. Direct constraints on minimal supersymmetry from Fermi-LAT observations of the dwarf galaxy Segue 1

    SciTech Connect (OSTI)

    Scott, Pat; Conrad, Jan; Edsj, Joakim; Bergstrm, Lars; Akrami, Yashar; Farnier, Christian E-mail: conrad@fysik.su.se E-mail: lbe@fysik.su.se E-mail: yashar@fysik.su.se

    2010-01-01

    The dwarf galaxy Segue 1 is one of the most promising targets for the indirect detection of dark matter. Here we examine what constraints 9 months of Fermi-LAT gamma-ray observations of Segue 1 place upon the Constrained Minimal Supersymmetric Standard Model (CMSSM), with the lightest neutralino as the dark matter particle. We use nested sampling to explore the CMSSM parameter space, simultaneously fitting other relevant constraints from accelerator bounds, the relic density, electroweak precision observables, the anomalous magnetic moment of the muon and B-physics. We include spectral and spatial fits to the Fermi observations, a full treatment of the instrumental response and its related uncertainty, and detailed background models. We also perform an extrapolation to 5 years of observations, assuming no signal is observed from Segue 1 in that time. Results marginally disfavour models with low neutralino masses and high annihilation cross-sections. Virtually all of these models are however already disfavoured by existing experimental or relic density constraints.

  17. Rechargeable Heat Battery's Secret Revealed

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

    Rechargeable Heat Battery Rechargeable Heat Battery's Secret Revealed Solar energy capture in chemical form makes it storable and transportable January 11, 2011 Contact: John ...

  18. Observations of MilkyWay Dwarf Spheroidal galaxies with the Fermi-LAT detector and

    SciTech Connect (OSTI)

    Abdo, A.A.; Ackermann, M.; Ajello, M.; Atwood, W.B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E.D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T.H.; Buson, S.; Caliandro, G.A.

    2010-05-26

    We report on the observations of 14 dwarf spheroidal galaxies with the Fermi Gamma-Ray Space Telescope taken during the first 11 months of survey mode operations. The Fermi telescope, which is conducting an all-sky {gamma}-ray survey in the 20 MeV to >300 GeV energy range, provides a new opportunity to test particle dark matter models through the expected {gamma}-ray emission produced by pair annihilation of weakly interacting massive particles (WIMPs). Local Group dwarf spheroidal galaxies, the largest galactic substructures predicted by the cold dark matter scenario, are attractive targets for such indirect searches for dark matter because they are nearby and among the most extreme dark matter dominated environments. No significant {gamma}-ray emission was detected above 100 MeV from the candidate dwarf galaxies. We determine upper limits to the {gamma}-ray flux assuming both power-law spectra and representative spectra from WIMP annihilation. The resulting integral flux above 100 MeV is constrained to be at a level below around 10{sup -9} photons cm{sup -2}s{sup -1}. Using recent stellar kinematic data, the {gamma}-ray flux limits are combined with improved determinations of the dark matter density profile in 8 of the 14 candidate dwarfs to place limits on the pair annihilation cross-section ofWIMPs in several widely studied extensions of the standard model, including its supersymmetric extension and other models that received recent attention. With the present data, we are able to rule out large parts of the parameter space where the thermal relic density is below the observed cosmological dark matter density and WIMPs (neutralinos here) are dominantly produced non-thermally, e.g. in models where supersymmetry breaking occurs via anomaly mediation. The {gamma}-ray limits presented here also constrain some WIMP models proposed to explain the Fermi and PAMELA e{sup +}e{sup -} data, including low-mass wino-like neutralinos and models with TeV masses pair-annihilating into muon-antimuon pairs.

  19. PROBING THE FERMI BUBBLES IN ULTRAVIOLET ABSORPTION: A SPECTROSCOPIC SIGNATURE OF THE MILKY WAY'S BICONICAL NUCLEAR OUTFLOW

    SciTech Connect (OSTI)

    Fox, Andrew J.; Bordoloi, Rongmon; Hernandez, Svea; Tumlinson, Jason; Savage, Blair D.; Wakker, Bart P.; Lockman, Felix J.; Bland-Hawthorn, Joss; Kim, Tae-Sun; Benjamin, Robert A.

    2015-01-20

    Giant lobes of plasma extend ?55 above and below the Galactic center, glowing in emission from gamma rays (the Fermi Bubbles) to microwaves and polarized radio waves. We use ultraviolet absorption-line spectra from the Hubble Space Telescope to constrain the velocity of the outflowing gas within these regions, targeting the quasar PDS456 (?, b = 10.4, +11.2). This sightline passes through a clear biconical structure seen in hard X-ray and gamma-ray emission near the base of the northern Fermi Bubble. We report two high-velocity metal absorption components, at v {sub LSR} = 235 and +250kms{sup 1}, which cannot be explained by co-rotating gas in the Galactic disk or halo. Their velocities are suggestive of an origin on the front and back side of an expanding biconical outflow emanating from the Galactic center. We develop simple kinematic biconical outflow models that can explain the observed profiles with an outflow velocity of ?900kms{sup 1} and a full opening angle of ?110 (matching the X-ray bicone). This indicates Galactic center activity over the last ?2.5-4.0Myr, in line with age estimates of the Fermi Bubbles. The observations illustrate the use of UV spectroscopy to probe the properties of swept-up gas venting into the Fermi Bubbles.

  20. A hadronic-leptonic model for the Fermi bubbles: Cosmic-rays in the galactic halo and radio emission

    SciTech Connect (OSTI)

    Fujita, Yutaka; Ohira, Yutaka; Yamazaki, Ryo

    2014-07-01

    We investigate non-thermal emission from the Fermi bubbles in a hadronic model. Cosmic-ray (CR) protons are accelerated at the forward shock of the bubbles. They interact with the background gas in the Galactic halo and create ?{sup 0}-decay gamma-rays and secondary electrons through proton-proton interaction. We follow the evolution of the CR protons and electrons by calculating their distribution functions. We find that the spectrum and the intensity profiles of ?{sup 0}-decay gamma-rays are consistent with observations. We predict that the shock front is located far ahead of the gamma-ray boundary of the Fermi bubbles. This naturally explains the fact that a clear temperature jump of thermal gas was not discovered at the gamma-ray boundary in recent Suzaku observations. We also consider re-acceleration of the background CRs in the Galactic halo at the shock front. We find that it can significantly affect the gamma-rays from the Fermi bubbles, unless the density of the background CRs is ? 10% of that in the Galactic disk. We indicate that secondary electrons alone cannot produce the observed radio emission from the Fermi bubbles. However, the radio emission from the outermost region of the bubbles can be explained if electrons are directly accelerated at the shock front with an efficiency of ?0.1% of that of protons.

  1. Spectrometer for X-ray emission experiments at FERMI free-electron-laser

    SciTech Connect (OSTI)

    Poletto, L. Frassetto, F.; Miotti, P.; Di Cicco, A.; Iesari, F.; Finetti, P.; Grazioli, C.; Kivimäki, A.; Stagira, S.; Coreno, M.

    2014-10-15

    A portable and compact photon spectrometer to be used for photon in-photon out experiments, in particular x-ray emission spectroscopy, is presented. The instrument operates in the 25–800 eV energy range to cover the full emissions of the FEL1 and FEL2 stages of FERMI. The optical design consists of two interchangeable spherical varied-lined-spaced gratings and a CCD detector. Different input sections can be accommodated, with/without an entrance slit and with/without an additional relay mirror, that allow to mount the spectrometer in different end-stations and at variable distances from the target area both at synchrotron and at free-electron-laser beamlines. The characterization on the Gas Phase beamline at ELETTRA Synchrotron (Italy) is presented.

  2. Orthogonality catastrophe as a consequence of qubit embedding in an ultracold Fermi gas

    SciTech Connect (OSTI)

    Goold, J. [Clarendon Laboratory, University of Oxford (United Kingdom); Physics Department, University College Cork, Cork (Ireland); Fogarty, T.; Lo Gullo, N.; Busch, Th. [Physics Department, University College Cork, Cork (Ireland); Paternostro, M. [Centre for Theoretical Atomic, Molecular and Optical Physics, Queen's University Belfast, Belfast BT7 1NN (United Kingdom)

    2011-12-15

    We investigate the behavior of a two-level atom coupled to a one-dimensional, ultracold Fermi gas. The sudden switching on of the scattering between the two entities leads to the loss of any coherence in the initial state of the impurity and we show that the exact dynamics of this process is strongly influenced by the effect of the orthogonality catastrophe within the gas. We highlight the relationship between the Loschmidt echo and the retarded Green's function - typically used to formulate the dynamical theory of the catastrophe - and demonstrate that the effect is reflected in the impurity dynamics. We show that the expected nonexponential decay of the spectral function can be observed using Ramsey interferometry on the two-level atom and comment on finite temperature effects.

  3. Current Research at the University of Chicago Enrico Fermi Institute and James Franck Institute

    ScienceCinema (OSTI)

    Simon Swordy

    2010-01-08

    These talks will give an overview of physics research at the University of Chicago centered in two research institutes. The Enrico Fermi Institute pursues research in some core areas of the physical sciences. These include cosmology, particle physics, theoretical physics, particle astrophysics, and cosmochemistry. The EFI talk will focus on some examples of these activities which together will provide a broad overview of EFI science. Research at the James Franck Institute centers on the intersection between physics, chemistry and materials science, with the aim to unravel the complex connections between structure and dynamics in condensed matter systems. The JFI is also home to the Chicago Materials Research Science and Engineering Center. The JFI talk will provide highlights of current projects by JFI members.

  4. Improved Measurement of the Positive-Muon Lifetime and Determination of the Fermi Constant

    SciTech Connect (OSTI)

    Chitwood, D. B.; Clayton, S. M.; Crnkovic, J.; Debevec, P. T.; Hertzog, D. W.; Kammel, P.; Kiburg, B.; Kunkle, J.; McNabb, R.; Mulhauser, F.; Oezben, C. S.; Polly, C. C.; Webber, D. M.; Winter, P.; Banks, T. I.; Crowe, K. M.; Lauss, B.; Barnes, M. J.; Wait, G. D.; Battu, S.

    2007-07-20

    The mean life of the positive muon has been measured to a precision of 11 ppm using a low-energy, pulsed muon beam stopped in a ferromagnetic target, which was surrounded by a scintillator detector array. The result, {tau}{sub {mu}}=2.197 013(24) {mu}s, is in excellent agreement with the previous world average. The new world average {tau}{sub {mu}}=2.197 019(21) {mu}s determines the Fermi constant G{sub F}=1.166 371(6)x10{sup -5} GeV{sup -2} (5 ppm). Additionally, the precision measurement of the positive-muon lifetime is needed to determine the nucleon pseudoscalar coupling g{sub P}.

  5. Constraining Inert Triplet dark matter by the LHC and FermiLAT

    SciTech Connect (OSTI)

    Ayazi, Seyed Yaser; Firouzabadi, S. Mahdi E-mail: smmfirouz@yahoo.com

    2014-11-01

    We study collider phenomenology of inert triplet scalar dark matter at the LHC. We discuss possible decay of Higgs boson to dark matter candidate and apply current experimental data for invisible Higgs decay and R{sub ??} to constrain parameter space of our model. We also investigate constraints on dark matter coming from forthcoming measurement, R{sub Z?} and mono-Higgs production. We analytically calculate the annihilation cross section of dark matter candidate into 2? and Z? and then use FermiLAT data to put constraints on parameter space of Inert Triplet Model. We found that this limit can be stronger than the constraints provided by LUX experiment for low mass DM.

  6. FERMI LIMIT ON THE NEUTRINO FLUX FROM GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Li Zhuo [Department of Astronomy and Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing (China); Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, Kunming (China)

    2013-06-20

    If gamma-ray bursts (GRBs) produce high-energy cosmic rays, neutrinos are expected to be generated in GRBs via photo-pion productions. However, we stress that the same process also generates electromagnetic (EM) emission induced by the secondary electrons and photons, and that the EM emission is expected to be correlated with neutrino flux. Using Fermi/Large Area Telescope results on gamma-ray flux from GRBs, the GRB neutrino emission is limited to be <20 GeV m{sup -2} per GRB event on average, which is independent of the unknown GRB proton luminosity. This neutrino limit suggests that IceCube, operating at full scale, requires stacking of more than 130 GRBs in order to detect one GRB muon neutrino.

  7. Two-band description of resonant superfluidity in atomic Fermi gases

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

    He, Lianyi; Hu, Hui; Liu, Xia -Ji

    2015-02-23

    Fermionic superfluidity in atomic Fermi gases across a Feshbach resonance is normally described by the atom-molecule theory, which treats the closed channel as a noninteracting point boson. In this work we present a theoretical description of the resonant superfluidity in analogy to the two-band superconductors. We employ the underlying two-channel scattering model of Feshbach resonance where the closed channel is treated as a composite boson with binding energy ε0 and the resonance is triggered by the microscopic interchannel coupling U12. The binding energy ε0 naturally serves as an energy scale of the system, which has been sent to infinity inmore » the atom-molecule theory. We show that the atom-molecule theory can be viewed as a leading-order low-energy effective theory of the underlying fermionic theory in the limit ε0→∞ and U12→0, while keeping the phenomenological atom-molecule coupling finite. The resulting two-band description of the superfluid state is in analogy to the BCS theory of two-band superconductors. In the dilute limit ε0→∞, the two-band description recovers precisely the atom-molecule theory. The two-band theory provides a natural approach to study the corrections because of a finite binding energy ε0 in realistic experimental systems. For broad and moderate resonances, the correction is not important for current experimental densities. However, for extremely narrow resonance, we find that the correction becomes significant. Lastly, the finite binding energy correction could be important for the stability of homogeneous polarized superfluid against phase separation in imbalanced Fermi gases across a narrow Feshbach resonance.« less

  8. Jet emission in young radio sources: A Fermi large area telescope gamma-ray view

    SciTech Connect (OSTI)

    Migliori, G.; Siemiginowska, A.; Kelly, B. C.; Stawarz, ?.; Celotti, A.; Begelman, M. C.

    2014-01-10

    We investigate the contribution of the beamed jet component to the high-energy emission in young and compact extragalactic radio sources, focusing for the first time on the ?-ray band. We derive predictions on the ?-ray luminosities associated with the relativistic jet assuming a leptonic radiative model. The high-energy emission is produced via Compton scattering by the relativistic electrons in a spherical region at the considered scales (?10 kpc). Simulations show a wide range of ?-ray luminosities, with intensities up to ?10{sup 46}-10{sup 48} erg s{sup 1} depending on the assumed jet parameters. We find a highly linear relation between the simulated X-ray and ?-ray luminosities that can be used to select candidates for ?-ray detection. We compare the simulated luminosity distributions in the radio, X-ray, and ?-ray regimes with observations for the largest sample of X-ray-detected young radio quasars. Our analysis of ?4-yr Fermi Large Area Telescope (LAT) data does not yield any statistically significant detections. However, the majority of the model-predicted ?-ray fluxes for the sample are near or below the current Fermi-LAT flux threshold and compatible with the derived upper limits. Our study gives constraints on the minimum jet power (L {sub jet,} {sub kin}/L {sub disk} > 0.01) of a potential jet contribution to the X-ray emission in the most compact sources (? 1 kpc) and on the particle-to-magnetic field energy density ratio that are in broad agreement with equipartition assumptions.

  9. Fermi level pinning in Fe-doped PbTe under pressure

    SciTech Connect (OSTI)

    Skipetrov, E. P. Kruleveckaya, O. V.; Skipetrova, L. A.; Slynko, E. I.; Slynko, V. E.

    2014-07-14

    We synthesize an iron-doped PbTe single-crystal ingot and investigate the phase and the elemental composition as well as galvanomagnetic properties in weak magnetic fields (4.2?K?T?300?K, B???0.07?T) of Pb{sub 1?y}Fe{sub y}Te alloys upon varying the iron content, at atmospheric pressure and under hydrostatic compression up to 10 kilobars. We find an increase of iron concentration along the length of the ingot and the appearance of microscopic inclusions enriched with iron in the heavily doped samples. Lightly doped alloys are characterized by the p-type metal conductivity. An increase of the iron impurity content leads to a decrease in the free hole concentration, a stabilization of galvanomagnetic parameters, indicating the pinning of the Fermi energy by the iron resonant impurity level lying under the bottom of the valence band, and to the p-n inversion of the conductivity type. Under pressure, the free hole concentration in the sample, in which the stabilization of galvanomagnetic parameters takes place, increases by approximately a factor of four due to the flow of electrons from the valence band to the iron-induced resonant level. Using the two-band Kane and the six-band Dimmock dispersion relations, the pressure dependence of the Fermi energy is calculated. The model of the electronic structure rearrangement of Pb{sub 1?y}Fe{sub y}Te under pressure is proposed. The energy position and the pressure coefficient of the resonant iron impurity level are determined.

  10. Mysteries of 'molecular machines' revealed

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

    Mysteries of 'molecular machines' revealed Mysteries of 'molecular machines' revealed Scientists are making it easier for pharmaceutical companies and researchers to see the detailed inner workings of molecular machines. December 22, 2014 A picture of a membrane protein called cysZ determined with Phenix software using data that could not previously be analyzed. A picture of a membrane protein called cysZ determined with Phenix software using data that could not previously be analyzed. Contact

  11. Non-Fermi-liquid, magnetic, and Kondo behavior in the heavy-fermion system U{sub {bold 2}}Cu{sub 17{minus}x}Al{sub x} (5{le}x{le}10)

    SciTech Connect (OSTI)

    Pietri, R.; Andraka, B.; Troc, R.; Tran, V.H.

    1997-12-01

    Results of specific heat, magnetic susceptibility, magnetization, and electrical resistivity for the heavy-fermion alloy system U{sub 2}Cu{sub 17{minus}x}Al{sub x} (5{le}x{le}10) are presented. The nonmagnetic alloy U{sub 2}Cu{sub 12}Al{sub 5} exhibits non-Fermi-liquid characteristics at low temperatures: {rho}{proportional_to}T and C/T {proportional_to} lnT. These non-Fermi-liquid characteristics also persist for other alloys corresponding to x{gt}5, which are all weakly magnetic. This magnetic behavior is revealed by a maximum in zero-field-cooled {chi}, a discrepancy between zero-field-cooled and field-cooled {chi} below this maximum, and a corresponding shoulder in C/T. The transition temperature identified by the shoulder in C/T is largest for x=8 (about 2.5 K) and decreases monotonically for either increasing or decreasing x. {copyright} {ital 1997} {ital The American Physical Society}

  12. Importance of the Fermi-surface topology to the superconducting state of the electron-doped pnictide Ba(Fe1-xCox)₂As₂

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

    Liu, Chang; Palczewski, A. D.; Dhaka, R. S.; Kondo, Takeshi; Fernandes, R. M.; Mun, E. D.; Hodovanets, H.; Thaler, A. N.; Schmalian, J.; Bud’ko, S. L.; et al

    2011-07-25

    We used angle-resolved photoemission spectroscopy and thermoelectric power to study the poorly explored, highly overdoped side of the phase diagram of Ba(Fe1-xCox)₂As₂ high-temperature superconductor. Our data demonstrate that several Lifshitz transitions—topological changes of the Fermi surface—occur for large x. The central hole barrel changes to ellipsoids that are centered at Z at x~0.11 and subsequently disappear around x~0.2; changes in thermoelectric power occur at similar x values. Tc decreases and goes to zero around x~0.15—between the two Lifshitz transitions. Beyond x=0.2 the central pocket becomes electron-like and superconductivity does not exist. Our observations reveal the importance of the underlying Fermiologymore » in electron-doped iron arsenides. We speculate that a likely necessary condition for superconductivity in these materials is the presence of the central hole pockets rather than nesting between central and corner pockets.« less

  13. FERMI-LAT OBSERVATIONS OF SUPERNOVA REMNANTS INTERACTING WITH MOLECULAR CLOUDS: W41, MSH 17-39, AND G337.7-0.1

    SciTech Connect (OSTI)

    Castro, Daniel; Figueroa-Feliciano, Enectali; Slane, Patrick; Carlton, Ashley

    2013-09-01

    We report the detection of {gamma}-ray emission coincident with three supernova remnants (SNRs) using data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. W41, G337.7-0.1, and MSH 17-39 are SNRs known to be interacting with molecular clouds, as evidenced by observations of hydroxyl (OH) maser emission at 1720 MHz in their directions and other observational information. SNR shocks are expected to be sites of cosmic-ray acceleration, and clouds of dense material can provide effective targets for production of {gamma}-rays from {pi}{sup 0}-decay. The observations reveal unresolved sources in the direction of G337.7-0.1 and MSH 17-39 and an extended source coincident with W41. We model their broadband emission (radio to {gamma}-ray) using a simple one-zone model, and after considering scenarios in which the MeV-TeV sources originate from either {pi}{sup 0}-decay or leptonic emission, we conclude that the {gamma}-rays are most likely produced through the hadronic channel.

  14. Observation of an electron band above the Fermi level in FeTe?.??Se?.?? from in-situ surface doping

    SciTech Connect (OSTI)

    Zhang, P.; Richard, P.; Xu, N.; Xu, Y. -M.; Ma, J.; Qian, T.; Fedorov, A. V.; Denlinger, J. D.; Gu, G. D.; Ding, H.

    2014-10-27

    We used in-situ potassium (K) evaporation to dope the surface of the iron-based superconductor FeTe?.??Se?.??. The systematic study of the bands near the Fermi level confirms that electrons are doped into the system, allowing us to tune the Fermi level of this material and to access otherwise unoccupied electronic states. In particular, we observe an electron band located above the Fermi level before doping that shares similarities with a small three-dimensional pocket observed in the cousin, heavily-electron-doped KFe??xSe? compound.

  15. Observation of an electron band above the Fermi level in FeTe₀.₅₅Se₀.₄₅ from in-situ surface doping

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

    Zhang, P.; Richard, P.; Xu, N.; Xu, Y. -M.; Ma, J.; Qian, T.; Fedorov, A. V.; Denlinger, J. D.; Gu, G. D.; Ding, H.

    2014-10-27

    We used in-situ potassium (K) evaporation to dope the surface of the iron-based superconductor FeTe₀.₅₅Se₀.₄₅. The systematic study of the bands near the Fermi level confirms that electrons are doped into the system, allowing us to tune the Fermi level of this material and to access otherwise unoccupied electronic states. In particular, we observe an electron band located above the Fermi level before doping that shares similarities with a small three-dimensional pocket observed in the cousin, heavily-electron-doped KFe₂₋xSe₂ compound.

  16. Alleviation of fermi-level pinning effect at metal/germanium interface by the insertion of graphene layers

    SciTech Connect (OSTI)

    Baek, Seung-heon Chris; Seo, Yu-Jin; Oh, Joong Gun; Albert Park, Min Gyu; Bong, Jae Hoon; Yoon, Seong Jun; Lee, Seok-Hee, E-mail: seokheelee@ee.kaist.ac.kr [Department of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Seo, Minsu; Park, Seung-young [Division of Materials Science, Korea Basic Science Institute (KBSI), 169-148 Daehak-ro, Yuseong-gu, Daejeon 305-333 (Korea, Republic of); Park, Byong-Guk [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2014-08-18

    In this paper, we report the alleviation of the Fermi-level pinning on metal/n-germanium (Ge) contact by the insertion of multiple layers of single-layer graphene (SLG) at the metal/n-Ge interface. A decrease in the Schottky barrier height with an increase in the number of inserted SLG layers was observed, which supports the contention that Fermi-level pinning at metal/n-Ge contact originates from the metal-induced gap states at the metal/n-Ge interface. The modulation of Schottky barrier height by varying the number of inserted SLG layers (m) can bring about the use of Ge as the next-generation complementary metal-oxide-semiconductor material. Furthermore, the inserted SLG layers can be used as the tunnel barrier for spin injection into Ge substrate for spin-based transistors.

  17. The electron-positron momentum density and Fermi surface of YBa sub 2 Cu sub 3 O sub 7-x

    SciTech Connect (OSTI)

    Haghighi, H.; Kaiser, J.H.; Rayner, S.; West, R.N. ); Liu, J.Z.; Shelton, R. ); Howell, R.H.; Solal, F.; Sterne, P.A.; Fluss, M.J. )

    1991-10-11

    The search for evidence of Fermi surface in the cuprate high temperature superconductors has provided the greatest challenge for the 2D ACAR technique thus far in its relatively short history. Much of the effort in both theory and experiment has focused on the Yttrium compound where the small size of samples, twinning and structural oxygen defects have made the experiments difficult, complicated the interpretation of results and led to some confusion. With the advent of good twin-free crystals that confusion has now been resolved. In this paper we shall briefly review the earlier experiments on twinned crystals and then describe in more detail, and in the context of the contemporary bandstructure theory, our recent clear resolution of a major Fermi surface section in untwinned crystals of YBa{sub 2}Cu{sub 3}O{sub 7-x}.

  18. Rechargeable Heat Battery's Secret Revealed

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

    Rechargeable Heat Battery Rechargeable Heat Battery's Secret Revealed Solar energy capture in chemical form makes it storable and transportable January 11, 2011 Contact: John Hules, JAHules@lbl.gov, +1 510 486 6008 2011-01-11-Heat-Battery.jpg A molecule of fulvalene diruthenium, seen in diagram, changes its configuration when it absorbs heat, and later releases heat when it snaps back to its original shape. Image: Jeffrey Grossman Broadly speaking, there have been two approaches to capturing the

  19. Reduction of Fermi level pinning and recombination at polycrystalline CdTe surfaces by laser irradiation

    SciTech Connect (OSTI)

    Simonds, Brian J.; Kheraj, Vipul; Palekis, Vasilios; Ferekides, Christos; Scarpulla, Michael A.

    2015-06-14

    Laser processing of polycrystalline CdTe is a promising approach that could potentially increase module manufacturing throughput while reducing capital expenditure costs. For these benefits to be realized, the basic effects of laser irradiation on CdTe must be ascertained. In this study, we utilize surface photovoltage spectroscopy (SPS) to investigate the changes to the electronic properties of the surface of polycrystalline CdTe solar cell stacks induced by continuous-wave laser annealing. The experimental data explained within a model consisting of two space charge regions, one at the CdTe/air interface and one at the CdTe/CdS junction, are used to interpret our SPS results. The frequency dependence and phase spectra of the SPS signal are also discussed. To support the SPS findings, low-temperature spectrally-resolved photoluminescence and time-resolved photoluminescence were also measured. The data show that a modest laser treatment of 250 W/cm{sup 2} with a dwell time of 20 s is sufficient to reduce the effects of Fermi level pinning at the surface due to surface defects.

  20. Fermi Large Area Telescope Measurements of the Diffuse Gamma-Ray Emission at Intermediate Galactic Latitudes

    SciTech Connect (OSTI)

    Abdo, A.A.; Ackermann, M.; Ajello, M.; Anderson, B.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B.M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Blandford, R.D.; Bloom, E.D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brez, A.; Brigida, M.; /more authors..

    2012-04-11

    The diffuse galactic {gamma}-ray emission is produced by cosmic rays (CRs) interacting with the interstellar gas and radiation field. Measurements by the Energetic Gamma-Ray Experiment Telescope (EGRET) instrument on the Compton Gamma-Ray Observatory indicated excess {gamma}-ray emission {ge}1 GeV relative to diffuse galactic {gamma}-ray emission models consistent with directly measured CR spectra (the so-called 'EGRET GeV excess'). The Large Area Telescope (LAT) instrument on the Fermi Gamma-Ray Space Telescope has measured the diffuse {gamma}-ray emission with improved sensitivity and resolution compared to EGRET. We report on LAT measurements for energies 100 MeV to 10 GeV and galactic latitudes 10{sup o} {le} |b| {le} 20{sup o}. The LAT spectrum for this region of the sky is well reproduced by a diffuse galactic {gamma}-ray emission model that is consistent with local CR spectra and inconsistent with the EGRET GeV excess.

  1. How electronic dynamics with Pauli exclusion produces Fermi-Dirac statistics

    SciTech Connect (OSTI)

    Nguyen, Triet S.; Nanguneri, Ravindra; Parkhill, John

    2015-04-07

    It is important that any dynamics method approaches the correct population distribution at long times. In this paper, we derive a one-body reduced density matrix dynamics for electrons in energetic contact with a bath. We obtain a remarkable equation of motion which shows that in order to reach equilibrium properly, rates of electron transitions depend on the density matrix. Even though the bath drives the electrons towards a Boltzmann distribution, hole blocking factors in our equation of motion cause the electronic populations to relax to a Fermi-Dirac distribution. These factors are an old concept, but we show how they can be derived with a combination of time-dependent perturbation theory and the extended normal ordering of Mukherjee and Kutzelnigg for a general electronic state. The resulting non-equilibrium kinetic equations generalize the usual Redfield theory to many-electron systems, while ensuring that the orbital occupations remain between zero and one. In numerical applications of our equations, we show that relaxation rates of molecules are not constant because of the blocking effect. Other applications to model atomic chains are also presented which highlight the importance of treating both dephasing and relaxation. Finally, we show how the bath localizes the electron density matrix.

  2. In-Flight Measurement of the Absolute Energy Scale of the Fermi Large Area Telescope

    SciTech Connect (OSTI)

    Ackermann, M.; Ajello, M.; Allafort, A.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E.D.; Bonamente, E.; Borgland, A.W.; Bouvier, A.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; /more authors..

    2012-09-20

    The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to survey the gamma-ray sky from 20 MeV to several hundreds of GeV. In this energy band there are no astronomical sources with sufficiently well known and sharp spectral features to allow an absolute calibration of the LAT energy scale. However, the geomagnetic cutoff in the cosmic ray electron-plus-positron (CRE) spectrum in low Earth orbit does provide such a spectral feature. The energy and spectral shape of this cutoff can be calculated with the aid of a numerical code tracing charged particles in the Earth's magnetic field. By comparing the cutoff value with that measured by the LAT in different geomagnetic positions, we have obtained several calibration points between {approx}6 and {approx}13 GeV with an estimated uncertainty of {approx}2%. An energy calibration with such high accuracy reduces the systematic uncertainty in LAT measurements of, for example, the spectral cutoff in the emission from gamma ray pulsars.

  3. Recent progress in III-V based ferromagnetic semiconductors: Band structure, Fermi level, and tunneling transport

    SciTech Connect (OSTI)

    Tanaka, Masaaki; Ohya, Shinobu Nam Hai, Pham

    2014-03-15

    Spin-based electronics or spintronics is an emerging field, in which we try to utilize spin degrees of freedom as well as charge transport in materials and devices. While metal-based spin-devices, such as magnetic-field sensors and magnetoresistive random access memory using giant magnetoresistance and tunneling magnetoresistance, are already put to practical use, semiconductor-based spintronics has greater potential for expansion because of good compatibility with existing semiconductor technology. Many semiconductor-based spintronics devices with useful functionalities have been proposed and explored so far. To realize those devices and functionalities, we definitely need appropriate materials which have both the properties of semiconductors and ferromagnets. Ferromagnetic semiconductors (FMSs), which are alloy semiconductors containing magnetic atoms such as Mn and Fe, are one of the most promising classes of materials for this purpose and thus have been intensively studied for the past two decades. Here, we review the recent progress in the studies of the most prototypical III-V based FMS, p-type (GaMn)As and its heterostructures with focus on tunneling transport, Fermi level, and bandstructure. Furthermore, we cover the properties of a new n-type FMS, (In,Fe)As, which shows electron-induced ferromagnetism. These FMS materials having zinc-blende crystal structure show excellent compatibility with well-developed III-V heterostructures and devices.

  4. Ground-state and dynamical properties of two-dimensional dipolar Fermi liquids

    SciTech Connect (OSTI)

    Abedinpour, Saeed H.; Asgari, Reza; Tanatar, B.; Polini, Marco

    2014-01-15

    We study the ground-state properties of a two-dimensional spin-polarized fluid of dipolar fermions within the EulerLagrange Fermi-hypernetted-chain approximation. Our method is based on the solution of a scattering Schrdinger equation for the pair amplitude ?(g(r)), where g(r) is the pair distribution function. A key ingredient in our theory is the effective pair potential, which includes a bosonic term from JastrowFeenberg correlations and a fermionic contribution from kinetic energy and exchange, which is tailored to reproduce the HartreeFock limit at weak coupling. Very good agreement with recent results based on quantum Monte Carlo simulations is achieved over a wide range of coupling constants up to the liquid-to-crystal quantum phase transition. Using the fluctuationdissipation theorem and a static approximation for the effective inter-particle interactions, we calculate the dynamical densitydensity response function, and furthermore demonstrate that an undamped zero-sound mode exists for any value of the interaction strength, down to infinitesimally weak couplings. -- Highlights: We have studied the ground state properties of a strongly correlated two-dimensional fluid of dipolar fermions. We have calculated the effective inter-particle interaction and the dynamical densitydensity response function. We have shown that an undamped zero sound mode exists at any value of the interaction strength.

  5. Implications of Fermi-LAT observations on the origin of IceCube neutrinos

    SciTech Connect (OSTI)

    Wang, Bin; Li, Zhuo [Department of Astronomy, School of Physics, Peking University, Beijing (China); Zhao, Xiaohong, E-mail: wang_b@pku.edu.cn, E-mail: zhaoxh@ynao.ac.cn, E-mail: zhuo.li@pku.edu.cn [Yunnan Observatories, Chinese Academy of Sciences, Kunming (China)

    2014-11-01

    The IceCube (IC) collaboration recently reported the detection of TeV-PeV extraterrestrial neutrinos whose origin is yet unknown. By the photon-neutrino connection in pp and p? interactions, we use the Fermi-LAT observations to constrain the origin of the IC detected neutrinos. We find that Galactic origins, i.e., the diffuse Galactic neutrinos due to cosmic ray (CR) propagation in the Milky Way, and the neutrinos from the Galactic point sources, may not produce the IC neutrino flux, thus these neutrinos should be of extragalactic origin. Moreover, the extragalactic gamma-ray bursts (GRBs) may not account for the IC neutrino flux, the jets of active galactic nuclei may not produce the IC neutrino spectrum, but the starburst galaxies (SBGs) may be promising sources. As suggested by the consistency between the IC detected neutrino flux and the Waxman-Bahcall bound, GRBs in SBGs may be the sources of both the ultrahigh energy, ?> 10{sup 19}eV, CRs and the 1100 PeV CRs that produce the IC detected TeV-PeV neutrinos.

  6. THE FERMI GBM GAMMA-RAY BURST SPECTRAL CATALOG: FOUR YEARS OF DATA

    SciTech Connect (OSTI)

    Gruber, David; Von Ahlefeld, Victoria Weller; Diehl, Roland; Greiner, Jochen; Von Kienlin, Andreas [Max-Planck-Institut fr extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany); Goldstein, Adam; Bhat, P. Narayana; Briggs, Michael S.; Connaughton, Valerie [University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Bissaldi, Elisabetta [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Byrne, Dave; Fitzpatrick, Gerard; Foley, Suzanne [School of Physics, University College Dublin, Belfield, Stillorgan Road, Dublin 4 (Ireland); Cleveland, William H. [Universities Space Research Association, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Fishman, Gerald J.; Kouveliotou, Chryssa [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Gibby, Melissa; Giles, Misty M. [Jacobs Technology, Inc., Huntsville, AL (United States); Guiriec, Sylvain [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Van der Horst, Alexander J. [Astronomical Institute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); and others

    2014-03-01

    In this catalog we present the updated set of spectral analyses of gamma-ray bursts (GRBs) detected by the Fermi Gamma-Ray Burst Monitor during its first four years of operation. It contains two types of spectra, time-integrated spectral fits and spectral fits at the brightest time bin, from 943 triggered GRBs. Four different spectral models were fitted to the data, resulting in a compendium of more than 7500 spectra. The analysis was performed similarly but not identically to Goldstein et al. All 487 GRBs from the first two years have been re-fitted using the same methodology as that of the 456 GRBs in years three and four. We describe, in detail, our procedure and criteria for the analysis and present the results in the form of parameter distributions both for the observer-frame and rest-frame quantities. The data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center.

  7. Collective mode evidence of high-spin bosonization in a trapped one-dimensional atomic Fermi gas with tunable spin

    SciTech Connect (OSTI)

    Liu, Xia-Ji Hu, Hui

    2014-11-15

    We calculate the frequency of collective modes of a one-dimensional repulsively interacting Fermi gas with high-spin symmetry confined in harmonic traps at zero temperature. This is a system realizable with fermionic alkaline-earth-metal atoms such as {sup 173}Yb, which displays an exact SU(?) spin symmetry with ??2 and behaves like a spinless interacting Bose gas in the limit of infinite spin components ???, namely high-spin bosonization. We solve the homogeneous equation of state of the high-spin Fermi system by using Bethe ansatz technique and obtain the density distribution in harmonic traps based on local density approximation. The frequency of collective modes is calculated by exactly solving the zero-temperature hydrodynamic equation. In the limit of large number of spin-components, we show that the mode frequency of the system approaches that of a one-dimensional spinless interacting Bose gas, as a result of high-spin bosonization. Our prediction of collective modes is in excellent agreement with a very recent measurement for a Fermi gas of {sup 173}Yb atoms with tunable spin confined in a two-dimensional tight optical lattice.

  8. Limits on dark matter annihilation signals from the Fermi LAT 4-year measurement of the isotropic gamma-ray background

    SciTech Connect (OSTI)

    Ackermann, M.

    2015-09-02

    We search for evidence of dark matter (DM) annihilation in the isotropic gamma-ray background (IGRB) measured with 50 months of Fermi Large Area Telescope (LAT) observations. An improved theoretical description of the cosmological DM annihilation signal, based on two complementary techniques and assuming generic weakly interacting massive particle (WIMP) properties, renders more precise predictions compared to previous work. More specifically, we estimate the cosmologically-induced gamma-ray intensity to have an uncertainty of a factor ~ 20 in canonical setups. We consistently include both the Galactic and extragalactic signals under the same theoretical framework, and study the impact of the former on the IGRB spectrum derivation. We find no evidence for a DM signal and we set limits on the DM-induced isotropic gamma-ray signal. Our limits are competitive for DM particle masses up to tens of TeV and, indeed, are the strongest limits derived from Fermi LAT data at TeV energies. This is possible thanks to the new Fermi LAT IGRB measurement, which now extends up to an energy of 820 GeV. As a result, we quantify uncertainties in detail and show the potential this type of search offers for testing the WIMP paradigm with a complementary and truly cosmological probe of DM particle signals.

  9. Vortex lattices in a rotating Fermi superfluid in the BCS-BEC crossover with many Landau levels

    SciTech Connect (OSTI)

    Song, Tie-ling; Ma, C.R.; Ma, Yong-li

    2012-08-15

    We present an explicit analytical analysis of the ground state of vortex lattice structure, based on a minimization of the generalized Gross-Pitaevskii energy functional in a trapped rotating Fermi superfluid gas. By a Bogoliubov-like transformation we find that the coarse-grained average of the atomic density varies as inverted parabola in three dimensional cases; the Fermi superfluid in the BEC regime enters into the lowest Landau level at fast rotation, in which the vortices form an almost regular triangular lattice over a central region and the vortex lattice is expanded along the radial direction in the outer region; the fluid in the unitarity and BCS regimes occupies many low-lying Landau levels, in which a trapped gas with a triangular vortex lattice has a superfluid core surrounded by a normal gas. The calculation is qualitatively consistent with recent numerical and experimental data both in the vortex lattice structure and vortex numbers and in the density profiles versus the stirring frequency in the whole BCS-BEC crossover. - Highlights: Black-Right-Pointing-Pointer We present an analysis of vortex lattice in an interacting trapped rotating Fermi superfluid gas. Black-Right-Pointing-Pointer Decomposing the vortex from the condensate, we can explain the vortex lattice. Black-Right-Pointing-Pointer The calculation is consistent with numerical and experimental data. Black-Right-Pointing-Pointer It can characterize experimentally properties in different regimes of the BCS-BEC crossover.

  10. Limits on dark matter annihilation signals from the Fermi LAT 4-year measurement of the isotropic gamma-ray background

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

    Ackermann, M.

    2015-09-02

    We search for evidence of dark matter (DM) annihilation in the isotropic gamma-ray background (IGRB) measured with 50 months of Fermi Large Area Telescope (LAT) observations. An improved theoretical description of the cosmological DM annihilation signal, based on two complementary techniques and assuming generic weakly interacting massive particle (WIMP) properties, renders more precise predictions compared to previous work. More specifically, we estimate the cosmologically-induced gamma-ray intensity to have an uncertainty of a factor ~ 20 in canonical setups. We consistently include both the Galactic and extragalactic signals under the same theoretical framework, and study the impact of the former onmore » the IGRB spectrum derivation. We find no evidence for a DM signal and we set limits on the DM-induced isotropic gamma-ray signal. Our limits are competitive for DM particle masses up to tens of TeV and, indeed, are the strongest limits derived from Fermi LAT data at TeV energies. This is possible thanks to the new Fermi LAT IGRB measurement, which now extends up to an energy of 820 GeV. As a result, we quantify uncertainties in detail and show the potential this type of search offers for testing the WIMP paradigm with a complementary and truly cosmological probe of DM particle signals.« less

  11. Gamma-Ray Observations of the Supernova Remnant RX J0852.0-4622 with the Fermi LAT

    SciTech Connect (OSTI)

    Tanaka, T.; Allafort, A.; Ballet, J.; Funk, S.; Giordano, F.; Hewitt, J.; Lemoine-Goumard, M.; Tajima, H.; Tibolla, O.; Uchiyama, Y.; /Stanford U., HEPL /KIPAC, Menlo Park

    2011-12-13

    We report on gamma-ray observations of the supernova remnant (SNR) RX J0852.0-4622 with the Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space Telescope. In the Fermi LAT data, we find a spatially extended source at the location of the SNR. The extension is consistent with the SNR size seen in other wavelengths such as X-rays and TeV gamma rays, leading to the identification of the gamma-ray source with the SNR. The spectrum is well described as a power law with a photon index of {Lambda} = 1.85 {+-} 0.06 (stat){sub -0.19}{sup +0.18} (sys), which smoothly connects to the H.E.S.S. spectrum in the TeV energy band. We discuss the gamma-ray emission mechanism based on multiwavelength data. The broadband data can be fit well by a model in which the gamma rays are of hadronic origin. We also consider a scenario with inverse Compton scattering of electrons as the emission mechanism of the gamma rays. Although the leptonic model predicts a harder spectrum in the Fermi LAT energy range, the model can fit the data considering the statistical and systematic errors.

  12. Relativistic Fermi-Ulam map: Application to WEGA stellarator lower hybrid power operation

    SciTech Connect (OSTI)

    Fuchs, V.; Seidl, J.; Krln, L.; Pnek, R.; Preinhaelter, J.; Urban, J.; Laqua, H. P.

    2014-06-15

    Analytical and numerical support is here provided in support of the explanation [Laqua et al., Plasma Phys. Controlled Fusion 56, 075022 (2014)] for the observation of ?MeV electrons during Lower Hybrid (LH) operation in EC pre-heated plasma at the WEGA stellarator [Otte et al., Nukleonika, 57, 171 (2012)]. In the quoted experiments, LH power from the WEGA TE{sub 11} circular waveguide, 9?cm diameter, un-phased, 2.45?GHz antenna, is radiated into a B???0.5?T, n{sup }{sub e}???5??10{sup 17} 1/m{sup 3} plasma at T{sub e}???10?eV bulk temperature with an EC-generated 50?keV population of electrons. In response, the fast electrons travel around flux or drift surfaces essentially without collisions, repeatedly interacting with the rf field close to the antenna mouth, and gaining energy in the process. Our WEGA antenna calculations indicate a predominantly standing electric field pattern at the antenna mouth. From a simple approximation of the corresponding Hamiltonian equations of motion, we derive here a relativistic generalization of the simplified area-preserving Fermi-Ulam (F-U) map [M. A. Lieberman and A. J. Lichtenberg, Phys. Rev. A 5, 1852 (1972), Lichtenberg et al., Physica D 1, 291 (1980)], allowing phase-space global stochasticity analysis. At typical WEGA plasma and antenna conditions, and with correlated phases between electronantenna electric field interaction events, the F-U map and supporting numerical simulations predict an absolute energy barrier in the range of 300?keV. In contrast, with random phases intervening between interaction events, the electron energy can reach ?MeV values, compatible with the measurements on WEGA [Laqua et al., Plasma Phys. Controlled Fusion 56, 075022 (2014)].

  13. Brightest Fermi-LAT flares of PKS 1222+216: implications on emission and acceleration processes

    SciTech Connect (OSTI)

    Kushwaha, Pankaj; Singh, K. P.; Sahayanathan, Sunder

    2014-11-20

    We present a high time resolution study of the two brightest ?-ray outbursts from a blazar PKS 1222+216 observed by the Fermi Large Area Telescope (LAT) in 2010. The ?-ray light curves obtained in four different energy bands, 0.1-3, 0.1-0.3, 0.3-1, and 1-3 GeV, with time bins of six hours, show asymmetric profiles with similar rise times in all the bands but a rapid decline during the April flare and a gradual one during the June flare. The light curves during the April flare show an ?2 day long plateau in 0.1-0.3 GeV emission, erratic variations in 0.3-1 GeV emission, and a daily recurring feature in 1-3 GeV emission until the rapid rise and decline within a day. The June flare shows a monotonic rise until the peak, followed by a gradual decline powered mainly by the multi-peak 0.1-0.3 GeV emission. The peak fluxes during both the flares are similar except in the 1-3 GeV band in April, which is twice the corresponding flux during the June flare. Hardness ratios during the April flare indicate spectral hardening in the rising phase followed by softening during the decay. We attribute this behavior to the development of a shock associated with an increase in acceleration efficiency followed by its decay leading to spectral softening. The June flare suggests hardening during the rise followed by a complicated energy dependent behavior during the decay. Observed features during the June flare favor multiple emission regions while the overall flaring episode can be related to jet dynamics.

  14. Examining the Fermi-LAT third source catalog in search of dark matter subhalos

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

    Bertoni, Bridget; Hooper, Dan; Linden, Tim

    2015-12-17

    Dark matter annihilations taking place in nearby subhalos could appear as gamma-ray sources without detectable counterparts at other wavelengths. In this study, we consider the collection of unassociated gamma-ray sources reported by the Fermi Collaboration in an effort to identify the most promising dark matter subhalo candidates. While we identify 24 bright, high-latitude, non-variable sources with spectra that are consistent with being generated by the annihilations of ~ 20–70 GeV dark matter particles (assuming annihilations to bbar b), it is not possible at this time to distinguish these sources from radio-faint gamma-ray pulsars. Deeper multi-wavelength observations will be essential tomore » clarify the nature of these sources. It is notable that we do not find any such sources that are well fit by dark matter particles heavier than ~100 GeV. We also study the angular distribution of the gamma-rays from this set of subhalo candidates, and find that the source 3FGL J2212.5+0703 prefers a spatially extended profile (of width ~ 0.15°) over that of a point source, with a significance of 4.2σ (3.6σ after trials factor). Although not yet definitive, this bright and high-latitude gamma-ray source is well fit as a nearby subhalo of mχ ≃ 20–50 GeV dark matter particles (annihilating to bb¯) and merits further multi-wavelength investigation. As a result, based on the subhalo distribution predicted by numerical simulations, we derive constraints on the dark matter annihilation cross section that are competitive to those resulting from gamma-ray observations of dwarf spheroidal galaxies, the Galactic Center, and the extragalactic gamma-ray background.« less

  15. Fermi monitoring of radio-loud narrow-line Seyfert 1 galaxies

    SciTech Connect (OSTI)

    Paliya, Vaidehi S.; Stalin, C. S.; Ravikumar, C. D.

    2015-02-01

    We present detailed analysis of the γ-ray flux variability and spectral properties of the five radio-loud narrow line Seyfert 1 (RL-NLSy1) galaxies, detected by the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope, namely 1H 0323+342, SBS 0846+513, PMN J0948+0022, PKS 1502+036, and PKS 2004−447. The first three sources show significant flux variations, including the rapid variability of a few hours by 1H 0323+342. The average γ-ray spectrum of 1H 0323+342 and PMN J0948+0022 shows deviation from a simple power-law (PL) behavior, whereas the PL model gives a better fit for the other three sources. The spectra of 1H 0323+342, SBS 0846+513, and PMN J0948+0022, which are in low, flaring, and moderately active states, respectively, show significant curvature. Such curvature in the γ-ray spectrum of 1H 0323+342 and PMN J0948+0022 could be due to the emission region located inside the broad line region (BLR) where the primary mechanism of the γ-ray emission is inverse-Compton (IC) scattering of BLR photons occurring in the Klein–Nishina regime. The γ-ray emission of SBS 0846+513 is explained by IC scattering of dusty torus photons, which puts the emission region outside the BLR and thus under the Thomson regime. Therefore, the observed curvature of SBS 0846+513 could be intrinsic to the particle energy distribution. The presence of curvature in the γ-ray spectrum and flux variability amplitudes of some of the RL-NLSy1 galaxies suggests that these sources could be akin to low/moderate jet power flat spectrum radio quasars.

  16. Examining the Fermi-LAT third source catalog in search of dark matter subhalos

    SciTech Connect (OSTI)

    Bertoni, Bridget; Hooper, Dan; Linden, Tim

    2015-12-17

    Dark matter annihilations taking place in nearby subhalos could appear as gamma-ray sources without detectable counterparts at other wavelengths. In this study, we consider the collection of unassociated gamma-ray sources reported by the Fermi Collaboration in an effort to identify the most promising dark matter subhalo candidates. While we identify 24 bright, high-latitude, non-variable sources with spectra that are consistent with being generated by the annihilations of ~ 20–70 GeV dark matter particles (assuming annihilations to bbar b), it is not possible at this time to distinguish these sources from radio-faint gamma-ray pulsars. Deeper multi-wavelength observations will be essential to clarify the nature of these sources. It is notable that we do not find any such sources that are well fit by dark matter particles heavier than ~100 GeV. We also study the angular distribution of the gamma-rays from this set of subhalo candidates, and find that the source 3FGL J2212.5+0703 prefers a spatially extended profile (of width ~ 0.15°) over that of a point source, with a significance of 4.2σ (3.6σ after trials factor). Although not yet definitive, this bright and high-latitude gamma-ray source is well fit as a nearby subhalo of mχ ≃ 20–50 GeV dark matter particles (annihilating to bb¯) and merits further multi-wavelength investigation. As a result, based on the subhalo distribution predicted by numerical simulations, we derive constraints on the dark matter annihilation cross section that are competitive to those resulting from gamma-ray observations of dwarf spheroidal galaxies, the Galactic Center, and the extragalactic gamma-ray background.

  17. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE FERMI GBM CATALOG OF COSMIC GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Hurley, K. [University of California, Berkeley, Space Sciences Laboratory, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Pal'shin, V. D.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Mazets, E. P.; Svinkin, D. S. [Ioffe Physical Technical Institute, St. Petersburg 194021 (Russian Federation); Briggs, M. S.; Connaughton, V. [University of Alabama in Huntsville, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Meegan, C. [Universities Space Research Association, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Goldsten, J. [Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723 (United States); Boynton, W.; Fellows, C.; Harshman, K. [University of Arizona, Department of Planetary Sciences, Tucson, AZ 85721 (United States); Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S.; Litvak, M. L.; Sanin, A. B. [Space Research Institute, 84/32, Profsoyuznaya, Moscow 117997 (Russian Federation); Rau, A., E-mail: khurley@ssl.berkeley.edu [Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, Postfach 1312, D-85748 Garching (Germany); and others

    2013-08-15

    We present Interplanetary Network (IPN) data for the gamma-ray bursts in the first Fermi Gamma-Ray Burst Monitor (GBM) catalog. Of the 491 bursts in that catalog, covering 2008 July 12 to 2010 July 11, 427 were observed by at least one other instrument in the nine-spacecraft IPN. Of the 427, the localizations of 149 could be improved by arrival time analysis (or {sup t}riangulation{sup )}. For any given burst observed by the GBM and one other distant spacecraft, triangulation gives an annulus of possible arrival directions whose half-width varies between about 0.'4 and 32 Degree-Sign , depending on the intensity, time history, and arrival direction of the burst, as well as the distance between the spacecraft. We find that the IPN localizations intersect the 1{sigma} GBM error circles in only 52% of the cases, if no systematic uncertainty is assumed for the latter. If a 6 Degree-Sign systematic uncertainty is assumed and added in quadrature, the two localization samples agree about 87% of the time, as would be expected. If we then multiply the resulting error radii by a factor of three, the two samples agree in slightly over 98% of the cases, providing a good estimate of the GBM 3{sigma} error radius. The IPN 3{sigma} error boxes have areas between about 1 arcmin{sup 2} and 110 deg{sup 2}, and are, on the average, a factor of 180 smaller than the corresponding GBM localizations. We identify two bursts in the IPN/GBM sample that did not appear in the GBM catalog. In one case, the GBM triggered on a terrestrial gamma flash, and in the other, its origin was given as ''uncertain''. We also discuss the sensitivity and calibration of the IPN.

  18. Caldicellulosiruptor Core and Pangenomes Reveal Determinants...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Caldicellulosiruptor Core and Pangenomes Reveal Determinants for Citation Details In-Document Search Title: Caldicellulosiruptor Core and Pangenomes Reveal ...

  19. Toward a comprehensive model for feedback by active galactic nuclei: New insights from M87 observations by LOFAR, Fermi, and H.E.S.S

    SciTech Connect (OSTI)

    Pfrommer, Christoph

    2013-12-10

    Feedback by active galactic nuclei (AGNs) appears to be critical in balancing radiative cooling of the low-entropy gas at the centers of galaxy clusters and in mitigating the star formation of elliptical galaxies. New observations of M87 enable us to put forward a comprehensive model for the physical heating mechanism. Low-frequency radio observations by LOFAR revealed the absence of fossil cosmic-ray (CR) electrons in the radio halo surrounding M87. This puzzle can be resolved by accounting for the CR release from the radio lobes and the subsequent mixing of CRs with the dense ambient intracluster gas, which thermalizes the electrons on a timescale similar to the radio halo age of 40 Myr. Hadronic interactions of similarly injected CR protons with the ambient gas should produce an observable gamma-ray signal in accordance with the steady emission of the low state of M87 detected by Fermi and H.E.S.S. Hence, we normalize the CR population to the gamma-ray emission, which shows the same spectral slope as the CR injection spectrum probed by LOFAR, thereby supporting a common origin. We show that CRs, which stream at the Alfvn velocity with respect to the plasma rest frame, heat the surrounding thermal plasma at a rate that balances that of radiative cooling on average at each radius. However, the resulting global thermal equilibrium is locally unstable and allows for the formation of the observed cooling multi-phase medium through thermal instability. Provided that CR heating balances cooling during the emerging 'cooling flow', the collapse of the majority of the gas is halted around 1 keVin accordance with X-ray data. We show that both the existence of a temperature floor and the similar radial scaling of the heating and cooling rates are generic predictions of the CR heating model.

  20. The Search for High Energy Extended Emission by Fermi-LAT from Swift-Localized Gamma-Ray Bursts

    SciTech Connect (OSTI)

    Chiang, J.; /Stanford U., HEPL /SLAC; Racusin, J.L.; /NASA, Goddard

    2012-05-01

    The brighter Fermi-LAT bursts have exhibited emission at energies >0.1 GeV that persists as late as {approx}2 ks after the prompt phase has nominally ended. This so-called 'extended emission' could arise from continued activity of the prompt burst mechanism or it could be the start of a high energy afterglow component. The high energy extended emission seen by the LAT has typically followed a t{sup -}{gamma} power-law temporal decay where {gamma} {approx} 1.2-1.7 and has shown no strong indication of spectral evolution. In contrast, the prompt burst emission generally displays strong spectral variability and more complex temporal changes in the LAT band. This differing behavior suggests that the extended emission likely corresponds to an early afterglow phase produced by an external shock. In this study, we look for evidence of high energy extended emission from 145 Swift-localized GRBs that have occurred since the launch of Fermi. A majority of these bursts were either outside of the LAT field-of-view or were otherwise not detected by the LAT during the prompt phase. However, because of the scanning operation of the Fermi satellite, the long-lived extended emission of these bursts may be detectable in the LAT data on the {approx}few ks time scale. We will look for emission from individual bursts and will perform a stacking analysis in order to set bounds on this emission for the sample as a whole. The detection of such emission would have implications for afterglow models and for the overall energy budget of GRBs.

  1. Direct observation of Fermi surface in YBa sub 2 Cu sub 3 O sub 7 minus. delta

    SciTech Connect (OSTI)

    Haghighi, H.; Kaiser, J.H.; Rayner, S.; West, R.N.; Liu, J.Z.; Shelton, R.; Howell, R.H.; Solal, F.; Fluss, M.J. University of California at Davis, Davis, California 95616 Lawrence Livermore National Laboratory, Livermore, California 94550 )

    1991-07-15

    We have performed a high-precision measurement (5{times}10{sup 8} coincidence counts) of the basal-plane electron-positron momentum density in well oxygenated, twin-free, single crystals of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}. The raw, processed, and {bold K}-space reduced spectra unambiguously show a clear image of a major Fermi surface sheet. The form and profile of that image are in substantial quantitative agreement with theoretical predictions of a {Gamma}-{ital X} electron ridge section associated with states in the CuO chains.

  2. Technical Design and Optimization Study for the FERMI@Elettra FELPhotoinjector

    SciTech Connect (OSTI)

    Lidia, Steven M.; Penco, Giuseppe; Trovo', Mauro

    2006-06-30

    The FERMI {at} Elettra FEL project will provide a novel, x-ray free electron laser user facility at Sincrotrone Trieste based on seeded and cascade FEL techniques. The electron beam source and injector systems play a crucial role in the success of the facility by providing the highest quality electron beams to the linac and FEL undulators. This Technical Note examines the critical technology components that make up the injector system, and demonstrates optimum beam dynamics solutions to achieve the required high quality electron beams. Section 2 provides an overview of the various systems and subsystems that comprise the photoinjector. The different operating modes of the injector are described as they pertain to the different linac configurations driven by the FEL and experimental design. For each mode, the required electron beam parameters are given. Sections 3 and 4 describe the critical beamline elements in the injector complex: the photocathode and drive laser, and the RF gun. The required drive laser parameters are given at the end of Section 3. Additional details on the design of the photoinjector drive laser systems are presented in a separate Technical Note. Design considerations for the RF gun are extensively presented in Section 4. There, we describe the variation of the cavity geometry to optimize the efficiency of the energy transfer to the electron beam. A study of the power coupling into the various cavity modes that interact within the bandwidth of the RF drive pulse is presented, followed by a study of the transient cavity response under several models and, finally, the effects on extracted beam quality. Section 5 describes the initial design for the low energy, off-axis diagnostic beamline. Beam dynamics simulations using ASTRA, elegant, and MAD are presented. Section 6 presents the optimization studies for the beam dynamics in the various operating modes. The optimized baseline configurations for the beamline and incident drive laser pulse are presented, supported by simulation results from space-charge tracking codes. Optimization of the beam transport through the downstream linac to the FEL undulator entrance requires significant deviations from the canonical ''flat-top'' temporal laser pulse distribution at the photocathode. The physics of nonlinear electron current emission are examined to determine the optimum temporal profile of the drive laser in order to produce the required linear current ramp at the injector exit. Parametric sensitivity studies are performed around the baseline configurations, and jitter studies are presented that analyze the stability of the solutions.

  3. Cray Reveal Tool Training: Sept 18, 2014

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

    Cray Reveal Tool Cray Reveal Tool Training: Sept 18, 2014 Revealplot1 Cray Reveal Webinar: A Tool to Help Porting to Manycore Heidi Poxon, Cray 10:00 - 11:00 PDT, September 18, 2014 Presented as a Web Event only Heidi Poxon, Technical Lead and Manager of Cray Performance Tools, will present a web training on the Cray Reveal Tool for porting to manycore systems. Reveal is a performance analysis and code optimization tool. Reveal assists users optimizing code by providing variable scoping feedback

  4. Fermi level control of compensating point defects during metalorganic chemical vapor deposition growth of Si-doped AlGaN

    SciTech Connect (OSTI)

    Bryan, Z; Bryan, I; Gaddy, BE; Reddy, P; Hussey, L; Bobea, M; Guo, W; Hoffmann, M; Kirste, R; Tweedie, J; Gerhold, M; Irving, DL; Sitar, Z; Collazo, R

    2014-12-01

    A Fermi-level control scheme for point defect management using above-bandgap UV illumination during growth is presented. We propose an extension to the analogy between the Fermi level and the electrochemical potential such that the electrochemical potential of a charged defect in a material with steady-state populations of free charge carriers may be expressed in terms of the quasi-Fermi levels. A series of highly Si-doped Al0.65Ga0.35N films grown by metalorganic chemical vapor deposition with and without UV illumination showed that samples grown under UV illumination had increased free carrier concentration, free carrier mobility, and reduced midgap photoluminescence all indicating a reduction in compensating point defects. (c) 2014 AIP Publishing LLC.

  5. Direct, experimental evidence of the Fermi surface in YBa sub 2 Cu sub 3 O sub 7-x

    SciTech Connect (OSTI)

    Haghighi, H.; Kaiser, J.H.; Rayner, S.L.; West, R.N. ); Liu, J.Z.; Shelton, R. ); Howell, R.H.; Sterne, P.A.; Solal, F.; Fluss, M.J. )

    1991-04-29

    We report new measurements of the electron-positron momentum spectra of YBa{sub 2}Cu{sub 3}O{sub 7-x} performed with ultra-high statistical precision. These data differ from previous results in two significant respects: They show the D{sub 2} symmetry appropriate for untwinned crystals and, more importantly, they show unmistakable, statistically significant, discontinuities that are evidence of a major Fermi surface section. These results provide a partial answer to a question of special significance to the study of high temperature superconductors i.e. the distribution of the electrons in the material, the electronic structure. Special consideration has been given both experimentally and theoretically to the existence and shape of a Fermi surface in the materials and to the superconducting gap. There are only three experimental techniques that can provide details of the electronic structure at useful resolutions. They are angular correlation of positron annihilation radiation, ACAR, angle resolved photo emission, PE, and de Haas van Alphen measurements. 11 refs., 4 figs.

  6. Fermi-LAT γ-ray anisotropy and intensity explained by unresolved radio-loud active galactic nuclei

    SciTech Connect (OSTI)

    Mauro, Mattia Di; Cuoco, Alessandro; Donato, Fiorenza; Siegal-Gaskins, Jennifer M. E-mail: alessandro.cuoco@to.infn.it E-mail: jsg@tapir.caltech.edu

    2014-11-01

    Radio-loud active galactic nuclei (AGN) are expected to contribute substantially to both the intensity and anisotropy of the isotropic γ-ray background (IGRB). In turn, the measured properties of the IGRB can be used to constrain the characteristics of proposed contributing source classes. We consider individual subclasses of radio-loud AGN, including low-, intermediate-, and high-synchrotron-peaked BL Lacertae objects, flat-spectrum radio quasars, and misaligned AGN. Using updated models of the γ-ray luminosity functions of these populations, we evaluate the energy-dependent contribution of each source class to the intensity and anisotropy of the IGRB. We find that collectively radio-loud AGN can account for the entirety of the IGRB intensity and anisotropy as measured by the Fermi Large Area Telescope (LAT). Misaligned AGN provide the bulk of the measured intensity but a negligible contribution to the anisotropy, while high-synchrotron-peaked BL Lacertae objects provide the dominant contribution to the anisotropy. In anticipation of upcoming measurements with the Fermi-LAT and the forthcoming Cherenkov Telescope Array, we predict the anisotropy in the broader energy range that will be accessible to future observations.

  7. Finite range and upper branch effects on itinerant ferromagnetism in repulsive Fermi gases: BetheGoldstone ladder resummation approach

    SciTech Connect (OSTI)

    He, Lianyi

    2014-12-15

    We investigate the ferromagnetic transition in repulsive Fermi gases at zero temperature with upper branch and effective range effects. Based on a general effective Lagrangian that reproduces precisely the two-body s-wave scattering phase shift, we obtain a nonperturbative expression of the energy density as a function of the polarization by using the BetheGoldstone ladder resummation. For hard sphere potential, the predicted critical gas parameter k{sub F}a=0.816 and the spin susceptibility agree well with the results from fixed-node diffusion Monte Carlo calculations. In general, positive and negative effective ranges have opposite effects on the critical gas parameter k{sub F}a: While a positive effective range reduces the critical gas parameter, a negative effective range increases it. For attractive potential or Feshbach resonance model, the many-body upper branch exhibits an energy maximum at k{sub F}a=? with ?=1.34 from the BetheGoldstone ladder resummation, which is qualitatively consistent with experimental results. The many-body T-matrix has a positive-energy pole for k{sub F}a>? and it becomes impossible to distinguish the bound state and the scattering state. These positive-energy bound states become occupied and therefore the upper branch reaches an energy maximum at k{sub F}a=?. In the zero range limit, there exists a narrow window (0.86Fermi gas. - Highlights: Nonperturbative interaction energy is obtained within the BetheGoldstone ladder resummation approach. Positive and negative effective ranges have opposite effects on the critical gas parameter. The upper branch Fermi gas exhibits an energy maximum and reentrant ferromagnetic transition. The ferromagnetic phase disappears for large and negative effective ranges.

  8. Schottky barrier height reduction for holes by Fermi level depinning using metal/nickel oxide/silicon contacts

    SciTech Connect (OSTI)

    Islam, Raisul, E-mail: raisul@stanford.edu; Shine, Gautam; Saraswat, Krishna C. [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

    2014-11-03

    We report the experimental demonstration of Fermi level depinning using nickel oxide (NiO) as the insulator material in metal-insulator-semiconductor (M-I-S) contacts. Using this contact, we show less than 0.1?eV barrier height for holes in platinum/NiO/silicon (Pt/NiO/p-Si) contact. Overall, the pinning factor was improved from 0.08 (metal/Si) to 0.26 (metal/NiO/Si). The experimental results show good agreement with that obtained from theoretical calculation. NiO offers high conduction band offset and low valence band offset with Si. By reducing Schottky barrier height, this contact can be used as a carrier selective contact allowing hole transport but blocking electron transport, which is important for high efficiency in photonic applications such as photovoltaics and optical detectors.

  9. Quantum Monte Carlo Study of the Ground-State Properties of a Fermi Gas in the BCS-BEC Crossover

    SciTech Connect (OSTI)

    Giorgini, S.; Astrakharchik, G. E.; Boronat, J.; Casulleras, J.

    2006-11-07

    The ground-state properties of a two-component Fermi gas with attractive short-range interactions are calculated using the fixed-node diffusion Monte Carlo method. The interaction strength is varied over a wide range by tuning the value of the s-wave scattering length of the two-body potential. We calculate the ground-state energy per particle and we characterize the equation of state of the system. Off-diagonal long-range order is investigated through the asymptotic behavior of the two-body density matrix. The condensate fraction of pairs is calculated in the unitary limit and on both sides of the BCS-BEC crossover.

  10. Pd/Cu Site Interchange and Non-Fermi-Liquid Behavior in UCu{sub 4}Pd

    SciTech Connect (OSTI)

    Booth, C.H.; MacLaughlin, D.E.; Heffner, R.H.; Kwei, G.H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); MacLaughlin, D.E. [Department of Physics, University of California, Riverside, California 92521 (United States)] [Department of Physics, University of California, Riverside, California 92521 (United States); Chau, R.; Maple, M.B. [Department of Physics, University of California, San Diego, California 92093 (United States)] [Department of Physics, University of California, San Diego, California 92093 (United States)

    1998-11-01

    X-ray-absorption fine-structure measurements of the local structure in UCu{sub 4}Pd are described which indicate a probable lattice-disorder origin for non-Fermi-liquid behavior in this material. Short Pd-Cu distances are observed, consistent with (24{plus_minus}3){percent} of the Pd atoms occupying nominally Cu sites. A {open_quotes}Kondo disorder{close_quotes} model, based on the effect on the local Kondo temperature T{sub K} of this interchange and some additional bond-length disorder, agrees quantitatively with previous experimental susceptibility data, and therefore also with specific heat and magnetic resonance experiments. {copyright} {ital 1998} {ital The American Physical Society }

  11. THE SECOND STAGE OF FERMI@ELETTRA: A SEEDED FEL IN THE SOFT X-RAY SPECTRAL RANGE

    SciTech Connect (OSTI)

    Allaria, E.; DeNinno, G.; Fawley, W. M.

    2009-08-14

    The second stage of the FERMI FEL, named FEL-2, is based on the principle of high-gain harmonic generation and relies on a double-seeded cascade. Recent developments stimulated a revision of the original setup, which was designed to cover the spectral range between 40 and 10 nm. The numerical simulations we present here show that the nominal (expected) electron-beam performance allows extension of the FEL spectral range down to 4 nm. A significant amount of third harmonic power can be also expected. We also show that the proposed setup is flexible enough for exploiting future developments of new seed sources, e.g., high harmonic generation in gases.

  12. The Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived From First-Year Fermi Large Area Telescope Data

    SciTech Connect (OSTI)

    Abdo, A. A.

    2011-08-19

    We report on the first Fermi Large Area Telescope (LAT) measurements of the so-called 'extra-galactic' diffuse {gamma}-ray emission (EGB). This component of the diffuse {gamma}-ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modelling of the bright foreground diffuse Galactic {gamma}-ray emission (DGE), the detected LAT sources and the solar {gamma}-ray emission. We find the spectrum of the EGB is consistent with a power law with differential spectral index {gamma} = 2.41 {+-} 0.05 and intensity, I(> 100 MeV) = (1.03 {+-} 0.17) x 10{sup -5} cm{sup -2} s{sup -1} sr{sup -1}, where the error is systematics dominated. Our EGB spectrum is featureless, less intense, and softer than that derived from EGRET data.

  13. Search for gamma-ray-emitting active galactic nuclei in the Fermi-LAT unassociated sample using machine learning

    SciTech Connect (OSTI)

    Doert, M.; Errando, M. E-mail: errando@astro.columbia.edu

    2014-02-10

    The second Fermi-LAT source catalog (2FGL) is the deepest all-sky survey available in the gamma-ray band. It contains 1873 sources, of which 576 remain unassociated. Machine-learning algorithms can be trained on the gamma-ray properties of known active galactic nuclei (AGNs) to find objects with AGN-like properties in the unassociated sample. This analysis finds 231 high-confidence AGN candidates, with increased robustness provided by intersecting two complementary algorithms. A method to estimate the performance of the classification algorithm is also presented, that takes into account the differences between associated and unassociated gamma-ray sources. Follow-up observations targeting AGN candidates, or studies of multiwavelength archival data, will reduce the number of unassociated gamma-ray sources and contribute to a more complete characterization of the population of gamma-ray emitting AGNs.

  14. Van der Waals Metal-Semiconductor Junction: Weak Fermi Level Pinning Enables Effective Tuning of Schottky Barrier

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

    Liu, Yuanyue; Stradins, Paul; Wei, Su-Huai

    2016-04-01

    Two-dimensional (2D) semiconductors have shown great potential for electronic and optoelectronic applications. However, their development is limited by a large Schottky barrier (SB) at the metal-semiconductor junction (MSJ), which is difficult to tune by using conventional metals because of the effect of strong Fermi level pinning (FLP). We show that this problem can be overcome by using 2D metals, which are bounded with 2D semiconductors through van der Waals (vdW) interactions. This success relies on a weak FLP at the vdW MSJ, which is attributed to the suppression of metal-induced gap states. Consequently, the SB becomes tunable and can vanishmore » with proper 2D metals (for example, H-NbS2). This work not only offers new insights into the fundamental properties of heterojunctions but also uncovers the great potential of 2D metals for device applications.« less

  15. Finite range and upper branch effects on itinerant ferromagnetism in repulsive Fermi gases: Bethe–Goldstone ladder resummation approach

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

    He, Lianyi

    2014-09-19

    In this study, we investigate the ferromagnetic transition in repulsive Fermi gases at zero temperature with upper branch and effective range effects. Based on a general effective Lagrangian that reproduces precisely the two-body ss-wave scattering phase shift, we obtain a nonperturbative expression of the energy density as a function of the polarization by using the Bethe–Goldstone ladder resummation. For hard sphere potential, the predicted critical gas parameter kFa = 0.816 and the spin susceptibility agree well with the results from fixed-node diffusion Monte Carlo calculations. In general, positive and negative effective ranges have opposite effects on the critical gas parametermore » kFa: While a positive effective range reduces the critical gas parameter, a negative effective range increases it. For attractive potential or Feshbach resonance model, the many-body upper branch exhibits an energy maximum at kFa = α with α = 1.34 from the Bethe–Goldstone ladder resummation, which is qualitatively consistent with experimental results. The many-body T-matrix has a positive-energy pole for kFa > α and it becomes impossible to distinguish the bound state and the scattering state. These positive-energy bound states become occupied and therefore the upper branch reaches an energy maximum at kFa = α. In the zero range limit, there exists a narrow window (0.86< kFa < 1.56) for the ferromagnetic phase. At sufficiently large negative effective range, the ferromagnetic phase disappears. On the other hand, the appearance of positive-energy bound state resonantly enhances the two-body decay rate around kFa = α and may prevent the study of equilibrium phases and ferromagnetism of the upper branch Fermi gas.« less

  16. Metagenomics, metatranscriptomics and single cell genomics reveal...

    Office of Scientific and Technical Information (OSTI)

    and single cell genomics reveal functional response of active Oceanospirillales to Gulf oil spill Citation Details In-Document Search Title: Metagenomics, metatranscriptomics and...

  17. Observation of an electron band above the Fermi level in FeTe{sub 0.55}Se{sub 0.45} from in-situ surface doping

    SciTech Connect (OSTI)

    Zhang, P.; Ma, J.; Qian, T.; Richard, P. Ding, H.; Xu, N.; Xu, Y.-M.; Fedorov, A. V.; Denlinger, J. D.; Gu, G. D.

    2014-10-27

    We used in-situ potassium (K) evaporation to dope the surface of the iron-based superconductor FeTe{sub 0.55}Se{sub 0.45}. The systematic study of the bands near the Fermi level confirms that electrons are doped into the system, allowing us to tune the Fermi level of this material and to access otherwise unoccupied electronic states. In particular, we observe an electron band located above the Fermi level before doping that shares similarities with a small three-dimensional pocket observed in the cousin, heavily electron-doped KFe{sub 2?x}Se{sub 2} compound.

  18. FINAL–REPORT NO. 2: INDEPENDENT CONFIRMATORY SURVEY SUMMARY AND RESULTS FOR THE ENRICO FERMI ATOMIC POWER PLANT, UNIT 1, NEWPORT, MICHIGAN (DOCKET NO. 50 16; RFTA 10-004)

    SciTech Connect (OSTI)

    Erika Bailey

    2011-07-07

    The Enrico Fermi Atomic Power Plant, Unit 1 (Fermi 1) was a fast breeder reactor design that was cooled by sodium and operated at essentially atmospheric pressure. On May 10, 1963, the Atomic Energy Commission (AEC) granted an operating license, DPR-9, to the Power Reactor Development Company (PRDC), a consortium specifically formed to own and operate a nuclear reactor at the Fermi 1 site. The reactor was designed for a maximum capability of 430 megawatts (MW); however, the maximum reactor power with the first core loading (Core A) was 200 MW. The primary system was filled with sodium in December 1960 and criticality was achieved in August 1963.

  19. Interfacial effects revealed by ultrafast relaxation dynamics...

    Office of Scientific and Technical Information (OSTI)

    Title: Interfacial effects revealed by ultrafast relaxation dynamics in BiFeO 3 YBa 2 Cu 3 O 7 bilayers Authors: Springer, D. ; Nair, Saritha K. ; He, Mi ; Lu, C. L. ; Cheong, S. ...

  20. Christmas burst reveals neutron star collision

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

    Christmas burst reveals neutron star collision Christmas burst reveals neutron star collision Called the Christmas Burst, GRB 101225A was freakishly lengthy and it produced radiation at unusually varying wavelengths. December 1, 2011 Los Alamos National Laboratory sits on top of a once-remote mesa in northern New Mexico with the Jemez mountains as a backdrop to research and innovation covering multi-disciplines from bioscience, sustainable energy sources, to plasma physics and new materials. Los

  1. Analyzing ocean mixing reveals insight on climate

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

    Analyzing ocean mixing reveals insight on climate Analyzing ocean mixing reveals insight on climate LANL scientists have developed a computer model that clarifies the complex processes driving ocean mixing in the vast eddies that swirl across hundreds of miles of open ocean. June 24, 2015 A three-dimensional spatial structure of mixing in an idealized ocean simulation, computed using Lagrangian particle statistics. A three-dimensional spatial structure of mixing in an idealized ocean simulation,

  2. Process for the reconstruction of three-dimensional images of an area of interest of an object comprising the combination of measurements over the entire object with measurements of an area of interest of said object, and appropriate installation

    DOE Patents [OSTI]

    Azevedo, Stephen; Grangeat, Pierre; Rizo, Philippe

    1995-01-01

    Process and installation making it possible to reconstitute precise images of an area of interest (2) of an object (1) by reducing the errors produced by the contribution of the compliment of the object. A first series of measurements is carried out, where a conical beam (10) only takes in the area of interest of the object (2) and this is followed by a second series of measurements in which the beam takes in the entire object. A combination of the measurements of the two series is carried out in order to make them compatible and obtain a more accurate image of the area of interest (2).

  3. Nodal to nodeless superconducting energy gap structure change concomitant with Fermi surface reconstruction in the heavy-fermion CeCoIn?

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

    Kim, Hyunsoo; Petrovic, C.; Tanatar, M. A.; Flint, R.; Hu, Rongwei; White, B. D.; Lum, I. K.; Maple, M. B.; Prozorov, R.

    2015-01-15

    The London penetration depth ?(T) was measured in single crystals of Ce1xRxCoIn?, R=La, Nd, and Yb down to Tmin ? 50 mK (Tc/Tmin ~50) using a tunnel-diode resonator. In the cleanest samples ??(T) is best described by the power law, ??(T) ? Tn, with n ~ 1, consistent with line nodes. Substitutions of Ce with La, Nd, and Yb lead to similar monotonic suppressions of Tc, however, the effects on ??(T) differ. While La and Nd dopings lead to increase of the exponent n and saturation at n ~ 2, as expected for a dirty nodal superconductor, Yb doping leadsmoreto n > 3, suggesting a change from nodal to nodeless superconductivity. This superconducting gap structure change happens in the same doping range where changes of the Fermi surface topology were reported, implying that the nodal structure and Fermi surface topology are closely linked.less

  4. The electron-positron momentum density and Fermi surface of YBa{sub 2}Cu{sub 3}O{sub 7-x}

    SciTech Connect (OSTI)

    Haghighi, H.; Kaiser, J.H.; Rayner, S.; West, R.N.; Liu, J.Z.; Shelton, R.; Howell, R.H.; Solal, F.; Sterne, P.A.; Fluss, M.J.

    1991-10-11

    The search for evidence of Fermi surface in the cuprate high temperature superconductors has provided the greatest challenge for the 2D ACAR technique thus far in its relatively short history. Much of the effort in both theory and experiment has focused on the Yttrium compound where the small size of samples, twinning and structural oxygen defects have made the experiments difficult, complicated the interpretation of results and led to some confusion. With the advent of good twin-free crystals that confusion has now been resolved. In this paper we shall briefly review the earlier experiments on twinned crystals and then describe in more detail, and in the context of the contemporary bandstructure theory, our recent clear resolution of a major Fermi surface section in untwinned crystals of YBa{sub 2}Cu{sub 3}O{sub 7-x}.

  5. FERMI LARGE AREA TELESCOPE DISCOVERY OF GeV GAMMA-RAY EMISSION FROM THE VICINITY OF SNR W44

    SciTech Connect (OSTI)

    Uchiyama, Yasunobu; Funk, Stefan; Katsuta, Junichiro; Lemoine-Goumard, Marianne; Torres, Diego F.

    2012-04-20

    We report the detection of GeV {gamma}-ray emission from the molecular cloud complex that surrounds the supernova remnant (SNR) W44 using the Large Area Telescope on board Fermi. While the previously reported {gamma}-ray emission from SNR W44 is likely to arise from the dense radio-emitting filaments within the remnant, the {gamma}-ray emission that appears to come from the surrounding molecular cloud complex can be ascribed to the cosmic rays (CRs) that have escaped from W44. The non-detection of synchrotron radio emission associated with the molecular cloud complex suggests the decay of {pi}{sup 0} mesons produced in hadronic collisions as the {gamma}-ray emission mechanism. The total kinetic energy channeled into the escaping CRs is estimated to be W{sub esc} {approx} (0.3-3) Multiplication-Sign 10{sup 50} erg, in broad agreement with the conjecture that SNRs are the main sources of Galactic CRs.

  6. A tale of tails. Dark matter interpretations of the Fermi GeV excess in light of background model systematics

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

    Calore, Francesca; Cholis, Ilias; McCabe, Christopher; Weniger, Christoph

    2015-03-10

    Several groups have identified an extended excess of gamma rays over the modeled foreground and background emissions towards the Galactic center (GC) based on observations with the Fermi Large Area Telescope. This excess emission is compatible in morphology and spectrum with a telltale sign from dark matter (DM) annihilation. Here, we present a critical reassessment of DM interpretations of the GC signal in light of the foreground and background uncertainties that some of us recently outlaid in Calore et al. (2014). We find that a much larger number of DM models fits the gamma-ray data than previously noted. In particular:more(1) In the case of DM annihilation into bb, we find that even large DM masses up to m??74 GeV are allowed at p-value >0.05. (2) Surprisingly, annihilation into nonrelativistic hh gives a good fit to the data. (3) The inverse Compton emission from ?+? with m? ~ 6070 GeV can also account for the excess at higher latitudes, |b|>2, both in its spectrum and morphology. We also present novel constraints on a large number of mixed annihilation channels, including cascade annihilation involving hidden sector mediators. In conclusion, we show that the current limits from dwarf spheroidal observations are not in tension with a DM interpretation when uncertainties on the DM halo profile are accounted for.less

  7. FIVE NEW MILLISECOND PULSARS FROM A RADIO SURVEY OF 14 UNIDENTIFIED FERMI-LAT GAMMA-RAY SOURCES

    SciTech Connect (OSTI)

    Kerr, M.; Camilo, F.; Johnson, T. J.; Ferrara, E. C.; Harding, A. K.; Guillemot, L.; Kramer, M.; Hessels, J.; Johnston, S.; Keith, M.; Reynolds, J. E.; Ransom, S. M.; Ray, P. S.; Wood, K. S.; Sarkissian, J. E-mail: fernando@astro.columbia.edu

    2012-03-20

    We have discovered five millisecond pulsars (MSPs) in a survey of 14 unidentified Fermi Large Area Telescope sources in the southern sky using the Parkes radio telescope. PSRs J0101-6422, J1514-4946, and J1902-5105 reside in binaries, while PSRs J1658-5324 and J1747-4036 are isolated. Using an ephemeris derived from timing observations of PSR J0101-6422 (P = 2.57 ms, DM = 12 pc cm{sup -3}), we have detected {gamma}-ray pulsations and measured its proper motion. Its {gamma}-ray spectrum (a power law of {Gamma} = 0.9 with a cutoff at 1.6 GeV) and efficiency are typical of other MSPs, but its radio and {gamma}-ray light curves challenge simple geometric models of emission. The high success rate of this survey-enabled by selecting {gamma}-ray sources based on their detailed spectral characteristics-and other similarly successful searches indicate that a substantial fraction of the local population of MSPs may soon be known.

  8. Interaction energy and itinerant ferromagnetism in a strongly interacting Fermi gas in the absence of molecule formation

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

    He, Lianyi

    2014-11-26

    In this study, we investigate the interaction energy and the possibility of itinerant ferromagnetism in a strongly interacting Fermi gas at zero temperature in the absence of molecule formation. The interaction energy is obtained by summing the perturbative contributions of Galitskii-Feynman type to all orders in the gas parameter. It can be expressed by a simple phase-space integral of an in-medium scattering phase shift. In both three and two dimensions (3D and 2D), the interaction energy shows a maximum before reaching the resonance from the Bose-Einstein condensate side, which provides a possible explanation of the experimental measurements of the interactionmore » energy. This phenomenon can be theoretically explained by the qualitative change of the nature of the binary interaction in the medium. The appearance of an energy maximum has significant effects on the itinerant ferromagnetism. In 3D, the ferromagnetic transition is reentrant and itinerant ferromagnetism exists in a narrow window around the energy maximum. In 2D, the present theoretical approach suggests that itinerant ferromagnetism does not exist, which reflects the fact that the energy maximum becomes much lower than the energy of the fully polarized state.« less

  9. A Tale of Tails. Dark Matter Interpretations of the Fermi GeV Excess in Light of Background Model Systematics

    SciTech Connect (OSTI)

    Calore, Francesca; Cholis, Ilias; McCabe, Christopher; Weniger, Christoph

    2015-03-10

    Several groups have identified an extended excess of gamma rays over the modeled foreground and background emissions towards the Galactic center (GC) based on observations with the Fermi Large Area Telescope. The excess emission is compatible in morphology and spectrum with a telltale sign from dark matter (DM) annihilation. Here, we present a critical reassessment of DM interpretations of the GC signal in light of the foreground and background uncertainties that some of us recently outlaid in Calore et al. (2014). We also find that a much larger number of DM models fits the gamma-ray data than previously noted. In particular: (1) In the case of DM annihilation into bb, we find that even large DM masses up to m??74 GeV are allowed at p-value >0.05. (2) Surprisingly, annihilation into nonrelativistic hh gives a good fit to the data. (3) The inverse Compton emission from ?+?- with m?~6070 GeV can also account for the excess at higher latitudes, |b|>2, both in its spectrum and morphology. We also present novel constraints on a large number of mixed annihilation channels, including cascade annihilation involving hidden sector mediators. Finally, we show that the current limits from dwarf spheroidal observations are not in tension with a DM interpretation when uncertainties on the DM halo profile are accounted for.

  10. Evidence for a Common Physical Description of Non-Fermi-Liquid Behavior in Chemically Substituted f -Electron Systems

    SciTech Connect (OSTI)

    de Andrade, M.C.; Chau, R.; Dickey, R.P.; Dilley, N.R.; Freeman, E.J.; Gajewski, D.A.; Maple, M.B. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, California 92093 (United States)] [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, California 92093 (United States); Movshovich, R. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Castro Neto, A.H.; Castilla, G. [Department of Physics, University of California, Riverside, California 92521 (United States)] [Department of Physics, University of California, Riverside, California 92521 (United States); Jones, B.A. [IBM Almaden Research Center, San Jose, California 95120-6099 (United States)] [IBM Almaden Research Center, San Jose, California 95120-6099 (United States)

    1998-12-01

    The non-Fermi-liquid (NFL) behavior observed in the low temperature specific heat C(T) and magnetic susceptibility {chi}(T) of many chemically substituted f -electron systems is analyzed within the context of a recently developed theory based on Griffiths{close_quote} singularities. Measurements of C(T) and {chi}(T) in the systems Th{sub 1{minus}x}U {sub x}Pd{sub 2}Al{sub 3} , Y{sub 1{minus}x}U {sub x}Pd{sub 3} , and UCu{sub 5{minus}x }M{sub x} (M=Pd,thinspPt ) are found to be consistent with C(T)/T{proportional_to}{chi}(T){proportional_to}T{sup {minus}1+{lambda}} predicted by this model with {lambda}{lt}1 in the NFL regime. These results suggest that the NFL properties observed in a wide variety of disordered f -electron systems can be described within the context of a common physical picture. {copyright} {ital 1998} {ital The American Physical Society}

  11. CONSTRAINTS ON THE SYNCHROTRON SHOCK MODEL FOR THE FERMI GRB 090820A OBSERVED BY GAMMA-RAY BURST MONITOR

    SciTech Connect (OSTI)

    Burgess, J. Michael; Preece, Robert D.; Briggs, Michael S.; Connaughton, Valerie; Guiriec, Sylvain; Paciesas, William S.; Bhat, P. N.; Chaplin, Vandiver; Goldstein, Adam; Baring, Matthew G.; Meegan, Charles A.; Bissaldi, Elisabetta; Diehl, Roland; Greiner, Jochen; Gruber, David; Fishman, Gerald J.; Gibby, Melissa; Giles, Misty E-mail: baring@rice.edu

    2011-11-01

    Discerning the radiative dissipation mechanism for prompt emission in gamma-ray bursts (GRBs) requires detailed spectroscopic modeling that straddles the {nu}F{sub {nu}} peak in the 100 keV-1 MeV range. Historically, empirical fits such as the popular Band function have been employed with considerable success in interpreting the observations. While extrapolations of the Band parameters can provide some physical insight into the emission mechanisms responsible for GRBs, these inferences do not provide a unique way of discerning between models. By fitting physical models directly, this degeneracy can be broken, eliminating the need for empirical functions; our analysis here offers a first step in this direction. One of the oldest, and leading, theoretical ideas for the production of the prompt signal is the synchrotron shock model. Here we explore the applicability of this model to a bright Fermi gamma-ray burst monitor (GBM) burst with a simple temporal structure, GRB 090820A. Our investigation implements, for the first time, thermal and non-thermal synchrotron emissivities in the RMFIT forward-folding spectral analysis software often used in GBM burst studies. We find that these synchrotron emissivities, together with a blackbody shape, provide at least as good a match to the data as the Band GRB spectral fitting function. This success is achieved in both time-integrated and time-resolved spectral fits.

  12. A Tale of Tails. Dark Matter Interpretations of the Fermi GeV Excess in Light of Background Model Systematics

    SciTech Connect (OSTI)

    Calore, Francesca; Cholis, Ilias; McCabe, Christopher; Weniger, Christoph

    2015-03-10

    Several groups have identified an extended excess of gamma rays over the modeled foreground and background emissions towards the Galactic center (GC) based on observations with the Fermi Large Area Telescope. The excess emission is compatible in morphology and spectrum with a telltale sign from dark matter (DM) annihilation. Here, we present a critical reassessment of DM interpretations of the GC signal in light of the foreground and background uncertainties that some of us recently outlaid in Calore et al. (2014). We also find that a much larger number of DM models fits the gamma-ray data than previously noted. In particular: (1) In the case of DM annihilation into b¯b, we find that even large DM masses up to mχ≃74 GeV are allowed at p-value >0.05. (2) Surprisingly, annihilation into nonrelativistic hh gives a good fit to the data. (3) The inverse Compton emission from μ+μ- with mχ~60–70 GeV can also account for the excess at higher latitudes, |b|>2°, both in its spectrum and morphology. We also present novel constraints on a large number of mixed annihilation channels, including cascade annihilation involving hidden sector mediators. Finally, we show that the current limits from dwarf spheroidal observations are not in tension with a DM interpretation when uncertainties on the DM halo profile are accounted for.

  13. A Tale of Tails. Dark Matter Interpretations of the Fermi GeV Excess in Light of Background Model Systematics

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

    Calore, Francesca; Cholis, Ilias; McCabe, Christopher; Weniger, Christoph

    2015-03-10

    Several groups have identified an extended excess of gamma rays over the modeled foreground and background emissions towards the Galactic center (GC) based on observations with the Fermi Large Area Telescope. The excess emission is compatible in morphology and spectrum with a telltale sign from dark matter (DM) annihilation. Here, we present a critical reassessment of DM interpretations of the GC signal in light of the foreground and background uncertainties that some of us recently outlaid in Calore et al. (2014). We also find that a much larger number of DM models fits the gamma-ray data than previously noted. Inmore » particular: (1) In the case of DM annihilation into b¯b, we find that even large DM masses up to mχ≃74 GeV are allowed at p-value >0.05. (2) Surprisingly, annihilation into nonrelativistic hh gives a good fit to the data. (3) The inverse Compton emission from μ+μ- with mχ~60–70 GeV can also account for the excess at higher latitudes, |b|>2°, both in its spectrum and morphology. We also present novel constraints on a large number of mixed annihilation channels, including cascade annihilation involving hidden sector mediators. Finally, we show that the current limits from dwarf spheroidal observations are not in tension with a DM interpretation when uncertainties on the DM halo profile are accounted for.« less

  14. Latent instabilities in metallic LaNiO₃ films by strain control of Fermi-surface topology

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

    Yoo, Hyang Keun; Hyun, Seung Ill; Moreschini, Luca; Kim, Hyeong -Do; Chang, Young Jun; Sohn, Chang Hee; Jeong, Da Woon; Sinn, Soobin; Kim, Yong Su; Bostwick, Aaron; et al

    2015-03-04

    Strain control is one of the most promising avenues to search for new emergent phenomena in transition metal-oxide films. Here, we investigate the strain-induced changes of electronic structures in strongly correlated LaNiO₃ (LNO) films, using angle-resolved photoemission spectroscopy and the dynamical mean-field theory. The strongly renormalized eg-orbital bands are systematically rearranged by misfit strain to change its fermiology. As tensile strain increases, the hole pocket centered at the A point elongates along the kz-axis and seems to become open, thus changing Fermi-surface (FS) topology from three- to quasi-two-dimensional. Concomitantly, the FS shape becomes flattened to enhance FS nesting. A FSmore » superstructure withQ₁ = (1/2,1/2,1/2) appears in all LNO films, while a tensile-strained LNO film has an additional Q₂ = (1/4,1/4,1/4) modulation, indicating that some instabilities are present in metallic LNO films. Charge disproportionation and spin-density-wave fluctuations observed in other nickelates might be their most probable origins« less

  15. ALS Reveals New State of Matter

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

    ALS Reveals New State of Matter ALS Reveals New State of Matter Print Wednesday, 13 October 2010 00:00 ALS user groups from Princeton and Stanford have been making waves this past year with several high-profile papers and extensive news coverage of their work on a new state of matter embodied by "topological insulators," materials that conduct electricity only on their surfaces. First identified at the ALS in 2007 by a Princeton team led by M. Zahid Hasan, topological insulators have

  16. Simulations Reveal Unusual Death for Ancient Stars

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

    Simulations Reveal Unusual Death for Ancient Stars Simulations Reveal Unusual Death for Ancient Stars Findings made possible with NERSC resources and Berkeley Lab Code September 29, 2014 Contact: Linda Vu, +1 510 495 2402, lvu@lbl.gov SMSweb.jpg This image is a slice through the interior of a supermassive star of 55,500 solar masses along the axis of symmetry. It shows the inner helium core in which nuclear burning is converting helium to oxygen, powering various fluid instabilities (swirling

  17. DISCOVERY OF NINE GAMMA-RAY PULSARS IN FERMI LARGE AREA TELESCOPE DATA USING A NEW BLIND SEARCH METHOD

    SciTech Connect (OSTI)

    Pletsch, H. J.; Allen, B.; Aulbert, C.; Fehrmann, H.; Guillemot, L.; Kramer, M.; Barr, E. D.; Champion, D. J.; Eatough, R. P.; Freire, P. C. C.; Ray, P. S.; Belfiore, A.; Dormody, M.; Camilo, F.; Caraveo, P. A.; Celik, Oe.; Ferrara, E. C.; Hessels, J. W. T.; Keith, M.; Kerr, M. E-mail: guillemo@mpifr-bonn.mpg.de; and others

    2012-01-10

    We report the discovery of nine previously unknown gamma-ray pulsars in a blind search of data from the Fermi Large Area Telescope (LAT). The pulsars were found with a novel hierarchical search method originally developed for detecting continuous gravitational waves from rapidly rotating neutron stars. Designed to find isolated pulsars spinning at up to kHz frequencies, the new method is computationally efficient and incorporates several advances, including a metric-based gridding of the search parameter space (frequency, frequency derivative, and sky location) and the use of photon probability weights. The nine pulsars have spin frequencies between 3 and 12 Hz, and characteristic ages ranging from 17 kyr to 3 Myr. Two of them, PSRs J1803-2149 and J2111+ 4606, are young and energetic Galactic-plane pulsars (spin-down power above 6 Multiplication-Sign 10{sup 35} erg s{sup -1} and ages below 100 kyr). The seven remaining pulsars, PSRs J0106+4855, J0622+3749, J1620-4927, J1746-3239, J2028+3332, J2030+4415, and J2139+4716, are older and less energetic; two of them are located at higher Galactic latitudes (|b| > 10 Degree-Sign ). PSR J0106+4855 has the largest characteristic age (3 Myr) and the smallest surface magnetic field (2 Multiplication-Sign 10{sup 11} G) of all LAT blind-search pulsars. PSR J2139+4716 has the lowest spin-down power (3 Multiplication-Sign 10{sup 33} erg s{sup -1}) among all non-recycled gamma-ray pulsars ever found. Despite extensive multi-frequency observations, only PSR J0106+4855 has detectable pulsations in the radio band. The other eight pulsars belong to the increasing population of radio-quiet gamma-ray pulsars.

  18. MULTI-WAVELENGTH EMISSION FROM THE FERMI BUBBLE. II. SECONDARY ELECTRONS AND THE HADRONIC MODEL OF THE BUBBLE

    SciTech Connect (OSTI)

    Cheng, K.-S.; Chernyshov, D. O.; Dogiel, V. A.; Ko, C.-M.

    2015-01-20

    We analyze the origin of the gamma-ray flux from the Fermi Bubbles (FBs) in the framework of the hadronic model in which gamma-rays are produced by collisions of relativistic protons with the protons of the background plasma in the Galactic halo. It is assumed in this model that the observed radio emission from the FBs is due to synchrotron radiation of secondary electrons produced by pp collisions. However, if these electrons lose their energy through synchrotron and inverse-Compton emission, the spectrum of secondary electrons will be too soft, and an additional arbitrary component of the primary electrons will be necessary in order to reproduce the radio data. Thus, a mixture of the hadronic and leptonic models is required for the observed radio flux. It was shown that if the spectrum of primary electrons is ∝E{sub e}{sup −2}, the permitted range of the magnetic field strength is within the 2-7 μG region. The fraction of gamma-rays produced by pp collisions can reach about 80% of the total gamma-ray flux from the FBs. If the magnetic field is <2 μG or >7 μG the model is unable to reproduce the data. Alternatively, the electrons in the FBs may lose their energy through adiabatic energy losses if there is a strong plasma outflow in the GC. Then, the pure hadronic model is able to reproduce characteristics of the radio and gamma-ray flux from the FBs. However, in this case the required magnetic field strength in the FBs and the power of CR sources are much higher than those following from observations.

  19. Fermi LAT Observation of Diffuse Gamma-Rays Produced through Interactions Between Local Interstellar Matter and High Energy Cosmic Rays

    SciTech Connect (OSTI)

    Abdo, A.A.; Ackermann, M.; Ajello, M.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Baughman, B.M.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bloom, E.D.; Bonamente, E.; Borgland, A.W.; Bregeon, J.; Brez, A.; Brigida, M.; Bruel, P.; Burnett, T.H.; /more authors..

    2012-03-30

    Observations by the Large Area Telescope (LAT) on the Fermi mission of diffuse {gamma}-rays in a mid-latitude region in the third quadrant (Galactic longitude l from 200{sup o} to 260{sup o} and latitude |b| from 22{sup o} to 60{sup o}) are reported. The region contains no known large molecular cloud and most of the atomic hydrogen is within 1 kpc of the solar system. The contributions of {gamma}-ray point sources and inverse Compton scattering are estimated and subtracted. The residual {gamma}-ray intensity exhibits a linear correlation with the atomic gas column density in energy from 100 MeV to 10 GeV. The measured integrated {gamma}-ray emissivity is (1.63 {+-} 0.05) x 10{sup -26} photons s{sup -1}sr{sup -1} H-atom{sup -1} and (0.66 {+-} 0.02) x 10{sup -26} photons s{sup -1}sr{sup -1} H-atom{sup -1} above 100 MeV and above 300 MeV, respectively, with an additional systematic error of {approx}10%. The differential emissivity from 100 MeV to 10 GeV agrees with calculations based on cosmic ray spectra consistent with those directly measured, at the 10% level. The results obtained indicate that cosmic ray nuclei spectra within 1 kpc from the solar system in regions studied are close to the local interstellar spectra inferred from direct measurements at the Earth within {approx}10%.

  20. THE FERMI-GBM X-RAY BURST MONITOR: THERMONUCLEAR BURSTS FROM 4U 0614+09

    SciTech Connect (OSTI)

    Linares, M.; Chakrabarty, D. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, Cambridge, MA 02139 (United States); Connaughton, V.; Bhat, P. N.; Briggs, M. S.; Preece, R. [CSPAR and Physics Department, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Jenke, P.; Kouveliotou, C.; Wilson-Hodge, C. A. [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Van der Horst, A. J. [Astronomical Institute 'Anton Pannekoek', University of Amsterdam, NL-1090-GE Amsterdam (Netherlands); Camero-Arranz, A.; Finger, M.; Paciesas, W. S. [Universities Space Research Association, Huntsville, AL 35805 (United States); Beklen, E. [Physics Department, Suleyman Demirel University, 32260 Isparta (Turkey); Von Kienlin, A. [Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, Postfach 1312, D-85748 Garching (Germany)

    2012-12-01

    Thermonuclear bursts from slowly accreting neutron stars (NSs) have proven difficult to detect, yet they are potential probes of the thermal properties of the NS interior. During the first year of a systematic all-sky search for X-ray bursts using the Gamma-ray Burst Monitor aboard the Fermi Gamma-ray Space Telescope we have detected 15 thermonuclear bursts from the NS low-mass X-ray binary 4U 0614+09 when it was accreting at nearly 1% of the Eddington limit. We measured an average burst recurrence time of 12 {+-} 3 days (68% confidence interval) between 2010 March and 2011 March, classified all bursts as normal duration bursts and placed a lower limit on the recurrence time of long/intermediate bursts of 62 days (95% confidence level). We discuss how observations of thermonuclear bursts in the hard X-ray band compare to pointed soft X-ray observations and quantify such bandpass effects on measurements of burst radiated energy and duration. We put our results for 4U 0614+09 in the context of other bursters and briefly discuss the constraints on ignition models. Interestingly, we find that the burst energies in 4U 0614+09 are on average between those of normal duration bursts and those measured in long/intermediate bursts. Such a continuous distribution in burst energy provides a new observational link between normal and long/intermediate bursts. We suggest that the apparent bimodal distribution that defined normal and long/intermediate duration bursts during the last decade could be due to an observational bias toward detecting only the longest and most energetic bursts from slowly accreting NSs.

  1. SGR J1550-5418 BURSTS DETECTED WITH THE FERMI GAMMA-RAY BURST MONITOR DURING ITS MOST PROLIFIC ACTIVITY

    SciTech Connect (OSTI)

    Van der Horst, A. J.; Finger, M. H. [Universities Space Research Association, NSSTC, Huntsville, AL 35805 (United States); Kouveliotou, C. [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Gorgone, N. M. [Connecticut College, New London, CT 06320 (United States); Kaneko, Y.; Goegues, E.; Lin, L. [Sabanc Latin-Small-Letter-Dotless-I University, Orhanl Latin-Small-Letter-Dotless-I -Tuzla, Istanbul 34956 (Turkey); Baring, M. G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Guiriec, S.; Bhat, P. N.; Chaplin, V. L.; Goldstein, A. [University of Alabama, Huntsville, CSPAR, Huntsville, AL 35805 (United States); Granot, J. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Watts, A. L. [Astronomical Institute 'Anton Pannekoek', University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Bissaldi, E.; Gruber, D. [Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, Postfach 1312, 85748 Garching (Germany); Gehrels, N.; Harding, A. K. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Gibby, M. H.; Giles, M. M., E-mail: A.J.VanDerHorst@uva.nl [Jacobs Technology, Inc., Huntsville, AL (United States); and others

    2012-04-20

    We have performed detailed temporal and time-integrated spectral analysis of 286 bursts from SGR J1550-5418 detected with the Fermi Gamma-ray Burst Monitor (GBM) in 2009 January, resulting in the largest uniform sample of temporal and spectral properties of SGR J1550-5418 bursts. We have used the combination of broadband and high time-resolution data provided with GBM to perform statistical studies for the source properties. We determine the durations, emission times, duty cycles, and rise times for all bursts, and find that they are typical of SGR bursts. We explore various models in our spectral analysis, and conclude that the spectra of SGR J1550-5418 bursts in the 8-200 keV band are equally well described by optically thin thermal bremsstrahlung (OTTB), a power law (PL) with an exponential cutoff (Comptonized model), and two blackbody (BB) functions (BB+BB). In the spectral fits with the Comptonized model, we find a mean PL index of -0.92, close to the OTTB index of -1. We show that there is an anti-correlation between the Comptonized E{sub peak} and the burst fluence and average flux. For the BB+BB fits, we find that the fluences and emission areas of the two BB functions are correlated. The low-temperature BB has an emission area comparable to the neutron star surface area, independent of the temperature, while the high-temperature BB has a much smaller area and shows an anti-correlation between emission area and temperature. We compare the properties of these bursts with bursts observed from other SGR sources during extreme activations, and discuss the implications of our results in the context of magnetar burst models.

  2. SIX YEARS OF FERMI-LAT AND MULTI-WAVELENGTH MONITORING OF THE BROAD-LINE RADIO GALAXY 3C 120: JET DISSIPATION AT SUB-PARSEC SCALES FROM THE CENTRAL ENGINE

    SciTech Connect (OSTI)

    Tanaka, Y. T.; Doi, A.; Inoue, Y.; Stawarz, L.; Cheung, C. C.; Fukazawa, Y.; Itoh, R.; Gurwell, M. A.; Tahara, M.; Kataoka, J.

    2015-01-30

    We present multi-wavelength monitoring results for the broad-line radio galaxy 3C 120 in the MeV/GeV, sub-millimeter, and 43 GHz bands over 6 yr. Over the past 2 yr, the Fermi-Large Area Telescope sporadically detected 3C 120 with high significance and the 230 GHz data also suggest an enhanced activity of the source. After the MeV/GeV detection from 3C 120 in MJD 56240–56300, 43 GHz Very Long Baseline Array (VLBA) monitoring revealed a brightening of the radio core, followed by the ejection of a superluminal knot. Since we observed the γ-ray and VLBA phenomena in temporal proximity to each other, it is naturally assumed that they are physically connected. This assumption was further supported by the subsequent observation that the 43 GHz core brightened again after a γ-ray flare occurred around MJD 56560. We can then infer that the MeV/GeV emission took place inside an unresolved 43 GHz core of 3C 120 and that the jet dissipation occurred at sub-parsec distances from the central black hole (BH), if we take the distance of the 43 GHz core from the central BH as ∼0.5 pc, as previously estimated from the time lag between X-ray dips and knot ejections. Based on our constraints on the relative locations of the emission regions and energetic arguments, we conclude that the γ rays are more favorably produced via the synchrotron self-Compton process, rather than inverse Compton scattering of external photons coming from the broad line region or hot dusty torus. We also derived the electron distribution and magnetic field by modeling the simultaneous broadband spectrum.

  3. ALS Reveals New State of Matter

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

    ALS Reveals New State of Matter Print ALS user groups from Princeton and Stanford have been making waves this past year with several high-profile papers and extensive news coverage of their work on a new state of matter embodied by "topological insulators," materials that conduct electricity only on their surfaces. First identified at the ALS in 2007 by a Princeton team led by M. Zahid Hasan, topological insulators have been the subject of intense interest, based on unusual quantum

  4. ALS Reveals New State of Matter

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

    ALS Reveals New State of Matter Print ALS user groups from Princeton and Stanford have been making waves this past year with several high-profile papers and extensive news coverage of their work on a new state of matter embodied by "topological insulators," materials that conduct electricity only on their surfaces. First identified at the ALS in 2007 by a Princeton team led by M. Zahid Hasan, topological insulators have been the subject of intense interest, based on unusual quantum

  5. ALS Reveals New State of Matter

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

    ALS Reveals New State of Matter Print ALS user groups from Princeton and Stanford have been making waves this past year with several high-profile papers and extensive news coverage of their work on a new state of matter embodied by "topological insulators," materials that conduct electricity only on their surfaces. First identified at the ALS in 2007 by a Princeton team led by M. Zahid Hasan, topological insulators have been the subject of intense interest, based on unusual quantum

  6. Fermi surface measurements in YBa sub 2 Cu sub 3 O sub 7-x and La sub 1. 874 Sr sub. 126 CuO sub 4

    SciTech Connect (OSTI)

    Howell, R.H.; Sterne, P.A.; Solal, F.; Fluss, M.J. ); Haghighi, H.; Kaiser, J.H.; Rayner, S.L.; West, R.N. ); Liu, J.Z; Shelton, R. ); Kojima, H. ); Kitazawa, K. )

    1991-06-25

    We report new, ultra high precision measurements of the electron-positron momentum spectra of YBa{sub 2}Cu{sub 3}O{sub 7-x} and La{sub 1.874}Sr{sub 126}CuO{sub 4}. The YBCO experiments were performed on twin free, single crystals and show discontinuities with the symmetry of the Fermi surface of the CuO chain bands. Conduction band and underlying features in LSCO share the same symmetry and can only be separated with the aid of LDA calculations. 5 refs., 3 figs.

  7. Time resolved spectroscopy of SGR J15505418 bursts detected with Fermi/gamma-ray burst monitor

    SciTech Connect (OSTI)

    Younes, G. [Universities Space Research Association, 6767 Old Madison Pike, Suite 450, Huntsville, AL 35806 (United States); Kouveliotou, C.; Collazzi, A. [Astrophysics Office, ZP 12, NASA-Marshall Space Flight Center, Huntsville, AL 35812 (United States); Van der Horst, A. J.; Watts, A. L.; Huppenkothen, D.; Van der Klis, M.; Van Putten, T. [Astronomical Institute "Anton Pannekoek," University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands); Baring, M. G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Granot, J. [Department of Natural Sciences, The Open University of Israel, 1 University Road, P.O. Box 808, Ranana 43537 (Israel); Bhat, P. N.; Gorgone, N. [University of Alabama in Huntsville CSPAR, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Gehrels, N.; Mcenery, J. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); G??, E.; Kaneko, Y.; Lin, L. [Sabanc? University, Orhanl?-Tuzla, ?stanbul 34956 (Turkey); Gruber, D.; Von Kienlin, A. [Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse, Postfach 1312, D-85748 Garching (Germany); Grunblatt, S. [University of Hawaii at Manoa, 2500 Campus Road, Honolulu, HI 96822 (United States); and others

    2014-04-10

    We report on a time-resolved spectroscopy of the 63 brightest bursts of SGR J15505418, detected with the Fermi/Gamma-ray Burst Monitor during its 2008-2009 intense bursting episode. We performed spectral analysis down to 4 ms timescales to characterize the spectral evolution of the bursts. Using a Comptonized model, we find that the peak energy, E {sub peak}, anti-correlates with flux, while the low-energy photon index remains constant at ? 0.8 up to a flux limit F ? 10{sup 5} erg s{sup 1} cm{sup 2}. Above this flux value, the E {sub peak}flux correlation changes sign, and the index positively correlates with the flux reaching ?1 at the highest fluxes. Using a two blackbody model, we find that the areas and fluxes of the two emitting regions correlate positively. Further, we study here for the first time the evolution of the temperatures and areas as a function of flux. We find that the areakT relation follows the lines of constant luminosity at the lowest fluxes, R {sup 2}?kT {sup 4}, with a break at the higher fluxes (F > 10{sup 5.5} erg s{sup 1} cm{sup 2}). The area of the high-kT component increases with the flux while its temperature decreases, which we interpret as being due to an adiabatic cooling process. The area of the low-kT component, on the other hand, appears to saturate at the highest fluxes, toward R {sub max} ? 30 km. Assuming that crust quakes are responsible for soft gamma repeater (SGR) bursts and considering R {sub max} as the maximum radius of the emitting photon-pair plasma fireball, we relate this saturation radius to a minimum excitation radius of the magnetosphere, and we put a lower limit on the internal magnetic field of SGR J15505418, B {sub int} ? 4.5 10{sup 15} G.

  8. Fermi Site Office Jobs

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

  9. FermiNews

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

    News Wilson Hall After 26 years under the same title, FERMINEWS ended its run with the June 2004 issue. A new magazine, SYMMETRY, became the successor to FERMINEWS in October 2004. SYMMETRY has a new design and a new outlook, but the same priority of connecting people and science-- the people who do the scientific work of particle physics, and the people who want to know about it. The FERMINEWS archive of past issues will remain right where it is. And by using the sign-up link below, you can

  10. Enrico Fermi - Hanford Site

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

    Enormous Blades for Offshore Energy Enormous Blades for Offshore Energy February 8, 2016 - 2:00pm Addthis Sandia's design for giant wind turbine blades that are stowed at dangerous wind speeds to reduce the risk of damage. | Courtesy of TrevorJohnston.com/Popular Science Stephanie Holinka Sandia National Laboratories A new design for gigantic blades longer than two football fields could help bring offshore 50-megawatt (MW) wind turbines to the United States and the world. Sandia's research on

  11. Fermi National Accelerator Laboratory

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

    Arizona, Arkansas, Deleware, Florida, Georgia, Iowa, Kansas, Missouri, Nebraska, New Hampshire, North Carolina, Oklahoma, Rhode Island, South Carolina, Tennesse, Wyoming...

  12. Fermi National Accelerator Laboratory

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

    North Carolina, Rhode Island, Tennessee, Vermont 1,000,001-5,000,000 Indiana, Maryland, New Hampshire, Washington Colorado, District of Columbia, Florida, Massachusetts,...

  13. Fermi National Accelerator Laboratory

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

    South Dakota, Texas Arizona, Connecticut, Indiana, Kansas, Maine, Missouri, Nebraska, New Hampshire, South Carolina, Washington, Wisconsin More than 5 million California,...

  14. Fermi National Accelerator Laboratory

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

    North Dakota, Utah, Wyoming 100,001-500,000 Arizona, Arkansas, Iowa, Kansas, Nebraska, New Hampshire, North Carolina, Oklahoma, Rhode Island, South Carolina, Vermont 500,001-1...

  15. New culturing tool reveals a full genome from single cells

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

    New culturing tool reveals New culturing tool reveals a full genome from single cells A new technique for genetic analysis, "gel microdroplets," helps scientists generate complete...

  16. DOE Testing Reveals Samsung Refrigerator Does Not Meet Energy...

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

    Reveals Samsung Refrigerator Does Not Meet Energy Star Requirements DOE Testing Reveals Samsung Refrigerator Does Not Meet Energy Star Requirements March 16, 2010 - 4:28pm Addthis...

  17. Study Reveals Challenges and Opportunities Related to Vessels...

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

    Reveals Challenges and Opportunities Related to Vessels for U.S. Offshore Wind Study Reveals ... The installation of offshore wind farms requires a highly specialized fleet of ...

  18. Metabolomics reveals metabolic biomarkers of Crohn's disease

    SciTech Connect (OSTI)

    Jansson, J.K.; Willing, B.; Lucio, M.; Fekete, A.; Dicksved, J.; Halfvarson, J.; Tysk, C.; Schmitt-Kopplin, P.

    2009-06-01

    The causes and etiology of Crohn's disease (CD) are currently unknown although both host genetics and environmental factors play a role. Here we used non-targeted metabolic profiling to determine the contribution of metabolites produced by the gut microbiota towards disease status of the host. Ion Cyclotron Resonance Fourier Transform Mass Spectrometry (ICR-FT/MS) was used to discern the masses of thousands of metabolites in fecal samples collected from 17 identical twin pairs, including healthy individuals and those with CD. Pathways with differentiating metabolites included those involved in the metabolism and or synthesis of amino acids, fatty acids, bile acids and arachidonic acid. Several metabolites were positively or negatively correlated to the disease phenotype and to specific microbes previously characterized in the same samples. Our data reveal novel differentiating metabolites for CD that may provide diagnostic biomarkers and/or monitoring tools as well as insight into potential targets for disease therapy and prevention.

  19. Protein Vivisection Reveals Elusive Intermediates in Folding

    SciTech Connect (OSTI)

    Zheng, Zhongzhou; Sosnick, Tobin R. (UC)

    2010-05-25

    Although most folding intermediates escape detection, their characterization is crucial to the elucidation of folding mechanisms. Here, we outline a powerful strategy to populate partially unfolded intermediates: A buried aliphatic residue is substituted with a charged residue (e.g., Leu {yields} Glu{sup -}) to destabilize and unfold a specific region of the protein. We applied this strategy to ubiquitin, reversibly trapping a folding intermediate in which the {beta}5-strand is unfolded. The intermediate refolds to a native-like structure upon charge neutralization under mildly acidic conditions. Characterization of the trapped intermediate using NMR and hydrogen exchange methods identifies a second folding intermediate and reveals the order and free energies of the two major folding events on the native side of the rate-limiting step. This general strategy may be combined with other methods and have broad applications in the study of protein folding and other reactions that require trapping of high-energy states.

  20. Inductively coupled plasmareactive ion etching of c- and a-plane AlGaN over the entire Al composition range: Effect of BCl{sub 3} pretreatment in Cl{sub 2}/Ar plasma chemistry

    SciTech Connect (OSTI)

    Shah, Amit P.; Laskar, Masihhur R.; Azizur Rahman, A.; Gokhale, Maheshwar R.; Bhattacharya, Arnab

    2013-11-15

    Inductively coupled plasma (ICP)reactive ion etching (RIE) patterning is a standard processing step for UV and optical photonic devices based on III-nitride materials. There is little research on ICP-RIE of high Al-content AlGaN alloys and for nonpolar nitride orientations. The authors present a comprehensive study of the ICP-RIE of c- and a-plane AlGaN in Cl{sub 2}/Ar plasma over the entire Al composition range. The authors find that the etch rate decreases in general with increasing Al content, with different behavior for c- and a-plane AlGaN. They also study the effect of BCl{sub 3} deoxidizing plasma pretreatment. An ICP deoxidizing BCl{sub 3} plasma with the addition of argon is more efficient in removal of surface oxides from Al{sub x}Ga{sub 1?x}N than RIE alone. These experiments show that Al{sub x}Ga{sub 1?x}N etching is affected by the higher binding energy of AlN and the higher affinity of oxygen to aluminum compared to gallium, with oxides on a-plane AlGaN more difficult to etch as compared to oxides on c-plane AlGaN, specifically for high Al composition materials. The authors achieve reasonably high etch rate (?350 nm/min) for high Al-content materials with a smooth surface morphology at a low DC bias of ??45 VDC.

  1. A possible explanation of low energy γ-ray excess from galactic centre and Fermi bubble by a Dark Matter model with two real scalars

    SciTech Connect (OSTI)

    Modak, Kamakshya Prasad; Majumdar, Debasish

    2015-03-09

    We promote the idea of multi-component Dark Matter (DM) to explain results from both direct and indirect detection experiments. In these models as contribution of each DM candidate to relic abundance is summed up to meet WMAP/Planck measurements of Ω{sub DM}, these candidates have larger annihilation cross-sections compared to the single-component DM models. We illustrate this fact by introducing an extra scalar to the popular single real scalar DM model. We also present detailed calculations for the vacuum stability bounds, perturbative unitarity and triviality constraints on this model. As direct detection experimental results still show some conflict, we kept our options open, discussing different scenarios with different DM mass zones. In the framework of our model we make an interesting observation: the existing direct detection experiments like CDMS II, CoGeNT, CRESST II, XENON 100 or LUX together with the observation of excess low energy γ-ray from galactic centre and Fermi bubble by Fermi Gamma-ray Space Telescope (FGST) already have the capability to distinguish between different DM halo profiles.

  2. Nodal to nodeless superconducting energy-gap structure change concomitant with Fermi-surface reconstruction in the heavy-fermion compound CeCoIn5

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

    Kim, Hyunsoo; Tanatar, M. A.; Flint, R.; Petrovic, C.; Hu, Rongwei; White, B. D.; Lum, I. K.; Maple, M. B.; Prozorov, R.

    2015-01-15

    The London penetration depth λ(T) was measured in single crystals of Ce1–xRxCoIn₅, R=La, Nd, and Yb down to Tmin ≈ 50 mK (Tc/Tmin ~50) using a tunnel-diode resonator. In the cleanest samples Δλ(T) is best described by the power law, Δλ(T) ∝ Tn, with n ~ 1, consistent with line nodes. Substitutions of Ce with La, Nd, and Yb lead to similar monotonic suppressions of Tc, however, the effects on Δλ(T) differ. While La and Nd dopings lead to increase of the exponent n and saturation at n ~ 2, as expected for a dirty nodal superconductor, Yb doping leadsmore » to n > 3, suggesting a change from nodal to nodeless superconductivity. As a result, this superconducting gap structure change happens in the same doping range where changes of the Fermi surface topology were reported, implying that the nodal structure and Fermi surface topology are closely linked.« less

  3. Topological crystalline insulator Pb{sub x}Sn{sub 1-x}Te thin films on SrTiO{sub 3} (001) with tunable Fermi levels

    SciTech Connect (OSTI)

    Guo, Hua; Liu, Jun-Wei; Wang, Zhen-Yu; Wu, Rui; Ji, Shuai-Hua; Duan, Wen-Hui; Chen, Xi Xue, Qi-Kun; Yan, Chen-Hui; Zhang, Zhi-Dong; Wang, Li-Li; He, Ke; Ma, Xu-Cun

    2014-05-01

    In this letter, we report a systematic study of topological crystalline insulator Pb{sub x}Sn{sub 1-x}Te (0 < x < 1) thin films grown by molecular beam epitaxy on SrTiO{sub 3}(001). Two domains of Pb{sub x}Sn{sub 1-x}Te thin films with intersecting angle of ? ? 45 were confirmed by reflection high energy diffraction, scanning tunneling microscopy, and angle-resolved photoemission spectroscopy (ARPES). ARPES study of Pb{sub x}Sn{sub 1-x}Te thin films demonstrated that the Fermi level of PbTe could be tuned by altering the temperature of substrate whereas SnTe cannot. An M-shaped valance band structure was observed only in SnTe but PbTe is in a topological trivial state with a large gap. In addition, co-evaporation of SnTe and PbTe results in an equivalent variation of Pb concentration as well as the Fermi level of Pb{sub x}Sn{sub 1-x}Te thin films.

  4. Revised FINAL–REPORT NO. 2: INDEPENDENT CONFIRMATORY SURVEY SUMMARY AND RESULTS FOR THE ENRICO FERMI ATOMIC POWER PLANT, UNIT 1, NEWPORT, MICHIGAN (DOCKET NO. 50 16; RFTA 10-004) 2018-SR-02-1

    SciTech Connect (OSTI)

    Erika Bailey

    2011-10-27

    The Enrico Fermi Atomic Power Plant, Unit 1 (Fermi 1) was a fast breeder reactor design that was cooled by sodium and operated at essentially atmospheric pressure. On May 10, 1963, the Atomic Energy Commission (AEC) granted an operating license, DPR-9, to the Power Reactor Development Company (PRDC), a consortium specifically formed to own and operate a nuclear reactor at the Fermi 1 site. The reactor was designed for a maximum capability of 430 megawatts (MW); however, the maximum reactor power with the first core loading (Core A) was 200 MW. The primary system was filled with sodium in December 1960 and criticality was achieved in August 1963. The reactor was tested at low power during the first couple years of operation. Power ascension testing above 1 MW commenced in December 1965 immediately following the receipt of a high-power operating license. In October 1966 during power ascension, zirconium plates at the bottom of the reactor vessel became loose and blocked sodium coolant flow to some fuel subassemblies. Two subassemblies started to melt and the reactor was manually shut down. No abnormal releases to the environment occurred. Forty-two months later after the cause had been determined, cleanup completed, and the fuel replaced, Fermi 1 was restarted. However, in November 1972, PRDC made the decision to decommission Fermi 1 as the core was approaching its burn-up limit. The fuel and blanket subassemblies were shipped off-site in 1973. Following that, the secondary sodium system was drained and sent off-site. The radioactive primary sodium was stored on-site in storage tanks and 55 gallon (gal) drums until it was shipped off-site in 1984. The initial decommissioning of Fermi 1 was completed in 1975. Effective January 23, 1976, DPR-9 was transferred to the Detroit Edison Company (DTE) as a 'possession only' license (DTE 2010a). This report details the confirmatory activities performed during the second Oak Ridge Institute for Science and Education (ORISE) site visit to Fermi 1 in November 2010. The survey was strategically planned during a Unit 2 (Fermi 2) outage to take advantage of decreased radiation levels that were observed and attributed to Fermi 2 from the operating unit during the first site visit. However, during the second visit there were elevated radiation levels observed and attributed to the partially dismantled Fermi 1 reactor vessel and a waste storage box located on the 3rd floor of the Fermi 1 Turbine Building. Confirmatory surveys (unshielded) performed directly in the line of sight of these areas were affected. The objective of the confirmatory survey was to verify that the final radiological conditions were accurately and adequately described in Final Status Survey (FSS) documentation, relative to the established release criteria. This objective was achieved by performing document reviews, as well as independent measurements and sampling. Specifically, documentation of the planning, implementation, and results of the FSS were evaluated; side-by-side FSS measurement and source comparisons were performed; site areas were evaluated relative to appropriate FSS classification; and areas were assessed for residual, undocumented contamination.

  5. Searching for dark matter annihilation from MilkyWay dwarf spheroidal galaxies with six years of Fermi Large Area Telescope data

    SciTech Connect (OSTI)

    Ackermann, M.

    2015-11-30

    The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on ?-ray observations of Milky Way dSphs based on six years of Fermi Large Area Telescope data processed with the new Pass8 event-level analysis. None of the dSphs are significantly detected in ? rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. As a result, these constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DM of mass ?100 GeV annihilating via quark and ?-lepton channels.

  6. Enrico Fermi Awards Ceremony for Dr. Mildred S. Dresselhaus and Dr. Burton Richter, May 2012 (Presentations, including remarks by Energy Secretary, Dr. Steven Chu)

    ScienceCinema (OSTI)

    Chu, Steven (U.S. Energy Secretary)

    2012-06-28

    The Fermi Award is a Presidential award and is one of the oldest and most prestigious science and technology honors bestowed by the U.S. Government. On May 7, 2012 it was conferred upon two exceptional scientists: Dr. Mildred Dresselhaus, 'for her scientific leadership, her major contributions to science and energy policy, her selfless work in science education and the advancement of diversity in the scientific workplace, and her highly original and impactful research,' and Dr. Burton Richter, 'for the breadth of his influence in the multiple disciplines of accelerator physics and particle physics, his profound scientific discoveries, his visionary leadership as SLAC Director, his leadership of science, and his notable contributions in energy and public policy.' Dr. John Holder, Director of the White House Office of Science and Technology Policy, opened the ceremony, and Dr. Bill Brinkman, Director of DOE's Office of Science introduced the main speaker, Dr. Steven Chu, U.S. Energy Secretary.

  7. Searching for dark matter annihilation from Milky Way dwarf spheroidal galaxies with six years of Fermi Large Area Telescope data

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

    Ackermann, M.

    2015-11-30

    The dwarf spheroidal satellite galaxies (dSphs) of the Milky Way are some of the most dark matter (DM) dominated objects known. We report on γ-ray observations of Milky Way dSphs based on six years of Fermi Large Area Telescope data processed with the new Pass8 event-level analysis. None of the dSphs are significantly detected in γ rays, and we present upper limits on the DM annihilation cross section from a combined analysis of 15 dSphs. As a result, these constraints are among the strongest and most robust to date and lie below the canonical thermal relic cross section for DMmore » of mass ≲100 GeV annihilating via quark and τ-lepton channels.« less

  8. Enrico Fermi Awards Ceremony for Dr. Allen J. Bard and Dr. Andrew Sessler, February 2014 (Presentations, including remarks by Energy Secretary, Dr. Ernest Moniz)

    ScienceCinema (OSTI)

    Moniz, Ernest [U.S. Energy Secretary

    2014-08-22

    The Fermi Award is a Presidential award and is one of the oldest and most prestigious science and technology honors bestowed by the U.S. Government. On February 3, 2014 it was conferred upon two exceptional scientists. The first to be recognized is Dr. Allen J. Bard, 'for international leadership in electrochemical science and technology, for advances in photoelectrochemistry and photocatalytic materials, processes, and devices, and for discovery and development of electrochemical methods including electrogenerated chemiluminescence and scanning electrochemical microscopy.' The other honoree is Dr. Andrew Sessler, 'for advancing accelerators as powerful tools of scientific discovery, for visionary direction of the research enterprise focused on challenges in energy and the environment, and for championing outreach and freedom of scientific inquiry worldwide.' Dr. Patricia Dehmer opened the ceremony, and Dr. Ernest Moniz presented the awards.

  9. High-energy gamma-ray emission from solar flares: Summary of Fermi large area telescope detections and analysis of two M-class flares

    SciTech Connect (OSTI)

    Ackermann, M.; Ajello, M.; Albert, A.; Allafort, A.; Bechtol, K.; Bottacini, E.; Buehler, R.; Baldini, L.; Barbiellini, G.; Bastieri, D.; Buson, S.; Bellazzini, R.; Bregeon, J.; Bissaldi, E.; Bonamente, E.; Bouvier, A.; Brandt, T. J.; Brigida, M.; Bruel, P.; and others

    2014-05-20

    We present the detections of 18 solar flares detected in high-energy γ-rays (above 100 MeV) with the Fermi Large Area Telescope (LAT) during its first 4 yr of operation. This work suggests that particle acceleration up to very high energies in solar flares is more common than previously thought, occurring even in modest flares, and for longer durations. Interestingly, all these flares are associated with fairly fast coronal mass ejections (CMEs). We then describe the detailed temporal, spatial, and spectral characteristics of the first two long-lasting events: the 2011 March 7 flare, a moderate (M3.7) impulsive flare followed by slowly varying γ-ray emission over 13 hr, and the 2011 June 7 M2.5 flare, which was followed by γ-ray emission lasting for 2 hr. We compare the Fermi LAT data with X-ray and proton data measurements from GOES and RHESSI. We argue that the γ-rays are more likely produced through pion decay than electron bremsstrahlung, and we find that the energy spectrum of the proton distribution softens during the extended emission of the 2011 March 7 flare. This would disfavor a trapping scenario for particles accelerated during the impulsive phase of the flare and point to a continuous acceleration process at play for the duration of the flares. CME shocks are known for accelerating the solar energetic particles (SEPs) observed in situ on similar timescales, but it might be challenging to explain the production of γ-rays at the surface of the Sun while the CME is halfway to the Earth. A stochastic turbulence acceleration process occurring in the solar corona is another likely scenario. Detailed comparison of characteristics of SEPs and γ-ray-emitting particles for several flares will be helpful to distinguish between these two possibilities.

  10. Unusual light in dark space revealed by Los Alamos, NASA

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

    Unusual light in dark space revealed by Los Alamos, NASA Unusual light in dark space revealed by Los Alamos, NASA By looking at the dark spaces between visible galaxies and stars ...

  11. Two Studies Reveal Details of Lithium-Battery Function

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

    Two Studies Reveal Details of Lithium-Battery Function Two Studies Reveal Details of Lithium-Battery Function Print Wednesday, 27 February 2013 00:00 Our way of life is deeply ...

  12. Secrets of the Motor That Drives Archaea Revealed

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

    Secrets of the Motor That Drives Archaea Revealed Secrets of the Motor That Drives Archaea Revealed Print Thursday, 14 February 2013 00:00 An international team led by John Tainer...

  13. NERSC Supercomputers Help Reveal Secrets of Natural Gas Reserves

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

    NERSC Helps Reveal Secrets of Natural Gas Reserves NERSC Supercomputers Help Reveal Secrets of Natural Gas Reserves New structural information could yield more efficient extraction of gas and oil from shale December 3, 2013 Supercomputers at the Department of Energy's National Energy Research Supercomputing Center (NERSC) helped scientists at Oak Ridge National Laboratory (ORNL) study gas and oil deposits in shale and reveal structural information that could lead to more efficient extraction of

  14. Two Studies Reveal Details of Lithium-Battery Function

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

    Two Studies Reveal Details of Lithium-Battery Function Print Our way of life is deeply intertwined with battery technologies that have enabled a mobile revolution powering cell...

  15. NERSC Supercomputers Help Reveal Secrets of Natural Gas Reserves

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

    NERSC Supercomputers Help Reveal Secrets of Natural Gas Reserves New structural information could yield more efficient extraction of gas and oil from shale December 3, 2013 ...

  16. X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery...

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

    Microscopy Reveals How Crystal Mechanics Drive Battery Performance Print Rechargeable lithium-ion batteries power most portable electronics and are becoming more widely used in...

  17. Sandia Energy - Simulations Reveal Ion Dynamics in Polymer Electrolyte

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

    and their effects on material properties is important for improved design. Recent molecular-dynamics simulations have revealed new details of ion motion in model ionomers....

  18. Structure of the TGF-Beta Receptor Complex Reveals Evolutionary...

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

    Structure of the TGF-Beta Receptor Complex Reveals Evolutionary Adaptations that have Led to Diversification of Function with the Superfamily Growth factors are peptides and ...

  19. ALS Capabilities Reveal Multiple Functions of Ebola Virus

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

    Reveal Multiple Functions of Ebola Virus Print A central dogma of molecular biology is that a protein's sequence dictates its fold, and the fold dictates its function....

  20. A Revealing Look Inside Passive and Active DPF Regeneration:...

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

    of Ash Formation and Transport A Revealing Look Inside Passive and Active DPF Regeneration: In-Situ Optical Analysis of Ash Formation and Transport Presents results from ...

  1. Death Domain Assembly Mechanism Revealed by Crystal Structure...

    Office of Scientific and Technical Information (OSTI)

    Core Complex Citation Details In-Document Search Title: Death Domain Assembly Mechanism Revealed by Crystal Structure of the Oligomeric PIDDosome Core Complex Authors: ...

  2. NREL: Photovoltaics Research - NREL Reveals Benefits of O2 Contact...

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

    Reveals Benefits of O2 Contact with Defects in 2D Semiconductors December 11, 2015 Researchers at the Energy Department's National Renewable Energy Laboratory (NREL) have explained...

  3. Crystal Structure of MC159 Reveals Molecular Mechanism of DISC...

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Search Results Journal Article: Crystal Structure of MC159 Reveals Molecular Mechanism of DISC Assembly and FLIP Inhibition Citation Details In-Document Search ...

  4. NREL: Wind Research - New Study Reveals Potential 30% Penetration...

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

    New Study Reveals Potential 30% Penetration of Wind and Solar for the Eastern Interconnection An illustrated map of the U.S. northeast and midwest showing transmission lines...

  5. The mystery of spectral breaks: Lyman continuum absorption by photon-photon pair production in the Fermi GeV spectra of bright blazars

    SciTech Connect (OSTI)

    Stern, Boris E. [Institute for Nuclear Research, Russian Academy of Sciences, Prospekt 60-letiya Oktyabrya 7a, Moscow 117312 (Russian Federation); Poutanen, Juri, E-mail: stern.boris@gmail.com, E-mail: juri.poutanen@utu.fi [Tuorla Observatory, University of Turku, Vislntie 20, FI-21500 Piikki (Finland)

    2014-10-10

    We re-analyze Fermi/LAT ?-ray spectra of bright blazars using the new Pass 7 version of the detector response files and detect breaks at ?5 GeV in the rest-frame spectra of 3C 454.3 and possibly also 4C +21.35, associated with the photon-photon pair production absorption by the He II Lyman continuum (LyC). We also detect significant breaks at ?20 GeV associated with hydrogen LyC in both the individual spectra and the stacked redshift-corrected spectrum of several bright blazars. The detected breaks in the stacked spectra univocally prove that they are associated with atomic ultraviolet emission features of the quasar broad-line region (BLR). The dominance of the absorption by the hydrogen Ly complex over He II, a small detected optical depth, and break energy consistent with head-on collisions with LyC photons imply that the ?-ray emission site is located within the BLR, but most of the BLR emission comes from a flat disk-like structure producing little opacity. Alternatively, the LyC emission region size might be larger than the BLR size measured from reverberation mapping, and/or the ?-ray emitting region is extended. These solutions would resolve the long-standing issue of how the multi-hundred GeV photons can escape from the emission zone without being absorbed by softer photons.

  6. Simultaneous Observations of PKS 2155--304 with H.E.S.S., Fermi, RXTE and ATOM: Spectral Energy Distributions and Variability in a Low State

    SciTech Connect (OSTI)

    Aharonian, F.; Akhperjanian, A.G.; Anton, G.; Barres de Almeida, U.; Bazer-Bachi, A.R.; Becherini, Y.; Behera, B.; Bernlohr, K.; Boisson, C.; Bochow, A.; Borrel, V.; Brion, E.; Brucker, J.; Brun, P.; Buhler, R.; Bulik, T.; Busching, I.; Boutelier, T.; Chadwick, P.M.; Charbonnier, A.; Chaves, R.C.G.; /more authors..

    2009-05-07

    We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of {gamma}-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little ({approx}30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.

  7. Search for gamma-ray emission from dark matter annihilation in the large magellanic cloud with the fermi large area telescope

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

    Buckley, Matthew R.; Charles, Eric; Gaskins, Jennifer M.; Brooks, Alyson M.; Drlica-Wagner, Alex; Martin, Pierrick; Zhao, Geng

    2015-05-05

    At a distance of 50 kpc and with a dark matter mass of ~1010 M⊙, the large magellanic cloud (LMC) is a natural target for indirect dark matter searches. We use five years of data from the Fermi Large Area Telescope (LAT) and updated models of the gamma-ray emission from standard astrophysical components to search for a dark matter annihilation signal from the LMC. We perform a rotation curve analysis to determine the dark matter distribution, setting a robust minimum on the amount of dark matter in the LMC, which we use to set conservative bounds on the annihilation cross section.more » The LMC emission is generally very well described by the standard astrophysical sources, with at most a 1–2σ excess identified near the kinematic center of the LMC once systematic uncertainties are taken into account. As a result, we place competitive bounds on the dark matter annihilation cross section as a function of dark matter particle mass and annihilation channel.« less

  8. Local electronic states of Fe{sub 4}N films revealed by x-ray absorption spectroscopy and x-ray magnetic circular dichroism

    SciTech Connect (OSTI)

    Ito, Keita; Toko, Kaoru; Suemasu, Takashi; Takeda, Yukiharu; Saitoh, Yuji; Oguchi, Tamio; Kimura, Akio

    2015-05-21

    We performed x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements at Fe L{sub 2,3} and N K-edges for Fe{sub 4}N epitaxial films grown by molecular beam epitaxy. In order to clarify the element specific local electronic structure of Fe{sub 4}N, we compared experimentally obtained XAS and XMCD spectra with those simulated by a combination of a first-principles calculation and Fermi's golden rule. We revealed that the shoulders observed at Fe L{sub 2,3}-edges in the XAS and XMCD spectra were due to the electric dipole transition from the Fe 2p core-level to the hybridization state generated by ?* anti-bonding between the orbitals of N 2p at the body-centered site and Fe 3d on the face-centered (II) sites. Thus, the observed shoulders were attributed to the local electronic structure of Fe atoms at II sites. As to the N K-edge, the line shape of the obtained spectra was explained by the dipole transition from the N 1s core-level to the hybridization state formed by ?* and ?* anti-bondings between the Fe 3d and N 2p orbitals. This hybridization plays an important role in featuring the electronic structures and physical properties of Fe{sub 4}N.

  9. TOC Mod 233-Entire Modification_signed.pdf

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

  10. Title Geology of the Great Basin. Copyright Issue Entire Book

    National Nuclear Security Administration (NNSA)

    Fiero, B. 101084 Document Date 1186 Document Type Book ERC Index number 05.09.128 Box Number 1672-1 Recipients Unversity of Nevada Reno Press ADI " Geology of the Great...

  11. A general protocol for restoration of entire river catchments

    SciTech Connect (OSTI)

    Stanford, J.A.; Frissell, C.A.; Ward, J.V.; Coutant, C.C.; Williams, R.N.; Lichatowich, J.A.

    1996-05-28

    Large catchment basins may be viewed as ecosystems with interactive natural and cultural attributes. Stream regulation severs ecological connectivity between channels and flood plains by reducing the range of natural flow and temperature variation, reduces the capacity of the ecosystem to sustain native biodiversity and bioproduction and promotes proliferation of non-native biota. However, regulated rivers regain normative attributes, which promote recovery of native biota, as distance from the dam increases and in relation to the mode of regulation. Therefore, reregulation of flow and temperature to normative pattern, coupled with elimination of pollutants and constrainment of nonnative biota, can naturally restore damaged habitats from headwaters to mouth. The expectation is rapid recovery of depressed populations of native species. The protocol requires: restoration of seasonal temperature patterns; restoration of peak flows needed to reconnect and periodically reconfigure channel and floodplain habitats; stabilization of base flows to revitalize the shallow water habitats; maximization of dam passage to allow restoration of metapopulation structure; change in the management belief system to rely on natural habitat restoration as opposed to artificial propagation, installation of artificial instream structures (river engineering) and artificial food web control; and, practice of adaptive ecosystem management.

  12. X-ray imaging reveals secrets in battery materials | Argonne...

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

    X-ray imaging reveals secrets in battery materials June 22, 2015 Tweet EmailPrint Imaging and data analysis techniques offer new approach to probing material properties In a new...

  13. Ternary structure reveals mechanism of a membrane diacylglycerol...

    Office of Scientific and Technical Information (OSTI)

    How nature has accomplished this extraordinary feat is revealed here in a crystal ... GrantContract Number: AC03-76SF00515 Type: Accepted Manuscript Journal Name: Nature ...

  14. Molecular Structure of Water at Gold Electrodes Revealed

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

    Molecular Structure of Water at Gold Electrodes Revealed Print The structure of liquid water has been intensely studied, but until recently, it has not been clear what happens to ...

  15. Covalent inhibition revealed by the crystal structure of the...

    Office of Scientific and Technical Information (OSTI)

    of the caspase-8p35 complex Citation Details In-Document Search Title: Covalent inhibition revealed by the crystal structure of the caspase-8p35 complex Authors: Xu, Guozhou ; ...

  16. Two Studies Reveal Details of Lithium-Battery Function

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

    Two Studies Reveal Details of Lithium-Battery Function Print Our way of life is deeply ... As conventional lithium-ion batteries approach their theoretical energy-storage limits, ...

  17. DOE Energy Star Testing Reveals Inefficient ASKO Dishwasher

    Broader source: Energy.gov [DOE]

    DOE testing in support of the Energy Star program has revealed that an ASKO dishwasher (model D5122XXLB), which the company had claimed was Energy Star compliant, consumes more energy than...

  18. ALS Capabilities Reveal Multiple Functions of Ebola Virus

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

    ALS Capabilities Reveal Multiple Functions of Ebola Virus ALS Capabilities Reveal Multiple Functions of Ebola Virus Print Friday, 13 June 2014 10:25 A central dogma of molecular biology is that a protein's sequence dictates its fold, and the fold dictates its function. Scientists typically expect that a protein has a singular structure (with some conformational variation), and that when an experimental structure is solved, it can used to understand the known biological function(s) of the

  19. Quo vadis? Microbial profiling revealed strong effects of cleanroom

    Office of Scientific and Technical Information (OSTI)

    maintenance and routes of contamination in indoor environments (Journal Article) | DOE PAGES Quo vadis? Microbial profiling revealed strong effects of cleanroom maintenance and routes of contamination in indoor environments « Prev Next » Title: Quo vadis? Microbial profiling revealed strong effects of cleanroom maintenance and routes of contamination in indoor environments Space agencies maintain highly controlled cleanrooms to ensure the demands of planetary protection. To study potential

  20. Global samples from nuclear contamination sites reveal unpredicted uranium

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

    and plutonium behavior Global samples reveal unpredicted uranium and plutonium behavior Global samples from nuclear contamination sites reveal unpredicted uranium and plutonium behavior Knowing how a chemical in soil reacts and transforms over time in response to neighboring elements, weather and heat is essential in determining whether that chemical is hazardous. June 15, 2015 Workers on a cleanup site at DOE's Hanford Site in southeastern Washington State, one of several sites sampled for

  1. Molecular Structure of Water at Gold Electrodes Revealed

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

    Molecular Structure of Water at Gold Electrodes Revealed Molecular Structure of Water at Gold Electrodes Revealed Print Wednesday, 25 March 2015 00:00 The structure of liquid water has been intensely studied, but until recently, it has not been clear what happens to it when a surface is introduced. ALS researchers have now made a first-ever observation of the molecular structure of liquid water at a gold surface under different charging conditions. This marks the first time that the scientific

  2. Death Domain Assembly Mechanism Revealed by Crystal Structure of the

    Office of Scientific and Technical Information (OSTI)

    Oligomeric PIDDosome Core Complex (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Death Domain Assembly Mechanism Revealed by Crystal Structure of the Oligomeric PIDDosome Core Complex Citation Details In-Document Search Title: Death Domain Assembly Mechanism Revealed by Crystal Structure of the Oligomeric PIDDosome Core Complex Authors: Park, Hyun Ho ; Logette, Emmanuelle ; Rausnser, Stefan ; Cuenin, Solange ; Walz, Thomas ; Tschopp, Jurg ; Wu, Hao [1] ;

  3. Atomic substitution reveals the structural basis for substrate adenine

    Office of Scientific and Technical Information (OSTI)

    recognition and removal by adenine DNA glycosylase (Journal Article) | SciTech Connect Atomic substitution reveals the structural basis for substrate adenine recognition and removal by adenine DNA glycosylase Citation Details In-Document Search Title: Atomic substitution reveals the structural basis for substrate adenine recognition and removal by adenine DNA glycosylase Adenine DNA glycosylase catalyzes the glycolytic removal of adenine from the promutagenic A {center_dot} oxoG base pair in

  4. Ice Sheet Model Reveals Most Comprehensive Projections for West

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

    Antarctica's Future Most Comprehensive Projections for West Antarctica's Future Revealed Ice Sheet Model Reveals Most Comprehensive Projections for West Antarctica's Future BISICLES Simulations Run at NERSC Help Estimate Ice Loss, Sea Level Rise August 18, 2015 Contact: Linda Vu, +1 510 495 2402, lvu@lbl.gov IceSheet Retreat in the Amundsen Sea Embayment in 2154 (Credit: Cornford et al., The Cryosphere, 2015) A new international study is the first to use a high-resolution, large-scale

  5. ALS Capabilities Reveal How Like Can Attract Like

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

    ALS Capabilities Reveal How Like Can Attract Like ALS Capabilities Reveal How Like Can Attract Like Print Wednesday, 26 March 2014 00:00 A Berkeley Lab research team working at the ALS has observed an unusual pairing that seems to go against a universal scientific truth-that opposite charges attract and like charges repel. Led by Berkeley Lab chemist Richard Saykally and theorist David Prendergast, researchers demonstrated that, when hydrated in water, positively charged ions (cations) can

  6. Rooted in Wonder: Joint Genome Institute Study Reveals Amazing World

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

    Underfoot | Department of Energy Rooted in Wonder: Joint Genome Institute Study Reveals Amazing World Underfoot Rooted in Wonder: Joint Genome Institute Study Reveals Amazing World Underfoot August 13, 2012 - 2:33pm Addthis By developing a better understanding of the microbes that affect the growth of other plants (crops like corn or wheat) researchers may be able to improve their growth -- or provide better care for them in times of drought. By developing a better understanding of the

  7. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

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

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print Wednesday, 31 October 2012 00:00 The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film

  8. Initiation factor 2 crystal structure reveals a different domain

    Office of Scientific and Technical Information (OSTI)

    organization from eukaryotic initiation factor 5B and mechanism among translational GTPases (Journal Article) | SciTech Connect Initiation factor 2 crystal structure reveals a different domain organization from eukaryotic initiation factor 5B and mechanism among translational GTPases Citation Details In-Document Search Title: Initiation factor 2 crystal structure reveals a different domain organization from eukaryotic initiation factor 5B and mechanism among translational GTPases Authors:

  9. Listening to the noise: random fluctuations reveal gene network parameters

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Journal Article: Listening to the noise: random fluctuations reveal gene network parameters Citation Details In-Document Search Title: Listening to the noise: random fluctuations reveal gene network parameters The cellular environment is abuzz with noise. The origin of this noise is attributed to the inherent random motion of reacting molecules that take part in gene expression and post expression interactions. In this noisy environment, clonal populations

  10. Metagenomic Profiling Reveals Lignocellulose Degrading System in a

    Office of Scientific and Technical Information (OSTI)

    Microbial Community Associated with a Wood-Feeding Beetle (Journal Article) | SciTech Connect Metagenomic Profiling Reveals Lignocellulose Degrading System in a Microbial Community Associated with a Wood-Feeding Beetle Citation Details In-Document Search Title: Metagenomic Profiling Reveals Lignocellulose Degrading System in a Microbial Community Associated with a Wood-Feeding Beetle + Authors: Scully, Erin ; Geib, Scott ; Hoover, Kelli ; Tien, Ming ; Tringe, Susannah ; Barry, Kerrie ; Rio,

  11. Transportation Energy Futures Study Reveals Potential for Deep Cuts to

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

    Petroleum Use and Carbon Emissions - News Releases | NREL Transportation Energy Futures Study Reveals Potential for Deep Cuts to Petroleum Use and Carbon Emissions Collaborative NREL and ANL project reveals opportunities for 80% reductions by 2050 March 15, 2013 The U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) and Argonne National Laboratory (ANL) today announced the release of the Transportation Energy Futures (TEF) study, an assessment of avenues to reach

  12. Two Studies Reveal Details of Lithium-Battery Function

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

    Two Studies Reveal Details of Lithium-Battery Function Two Studies Reveal Details of Lithium-Battery Function Print Wednesday, 27 February 2013 00:00 Our way of life is deeply intertwined with battery technologies that have enabled a mobile revolution powering cell phones, laptops, medical devices, and cars. As conventional lithium-ion batteries approach their theoretical energy-storage limits, new technologies are emerging to address the long-term energy-storage improvements needed for mobile

  13. Favorable Supplies, Costs, Environmental Profile for Natural Gas Revealed

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

    in New Department of Energy Study | Department of Energy Favorable Supplies, Costs, Environmental Profile for Natural Gas Revealed in New Department of Energy Study Favorable Supplies, Costs, Environmental Profile for Natural Gas Revealed in New Department of Energy Study August 23, 2012 - 1:00pm Addthis Washington, DC - The nation's large resource base of natural gas can be used for cost-effective power generation, with environmental burdens coming primarily from fuel combustion, not

  14. Structure of a mutant [beta] toxin from Staphylococcus aureus reveals

    Office of Scientific and Technical Information (OSTI)

    domain swapping and conformational flexibility (Journal Article) | SciTech Connect Structure of a mutant [beta] toxin from Staphylococcus aureus reveals domain swapping and conformational flexibility Citation Details In-Document Search Title: Structure of a mutant [beta] toxin from Staphylococcus aureus reveals domain swapping and conformational flexibility The 3.35 {angstrom} resolution crystal structure of a mutant form of the staphylococcal sphingomyelinase {beta} toxin in which a

  15. Structures of Xenopus Embryonic Epidermal Lectin Reveal a Conserved

    Office of Scientific and Technical Information (OSTI)

    Mechanism of Microbial Glycan Recognition (Journal Article) | SciTech Connect Journal Article: Structures of Xenopus Embryonic Epidermal Lectin Reveal a Conserved Mechanism of Microbial Glycan Recognition Citation Details In-Document Search Title: Structures of Xenopus Embryonic Epidermal Lectin Reveal a Conserved Mechanism of Microbial Glycan Recognition Authors: Wangkanont, Kittikhun ; Wesener, Darryl A. ; Vidani, Jack A. ; Kiessling, Laura L. ; Forest, Katrina T. [1] + Show Author

  16. New Mathematical Method Reveals Where Genes Switch On or Off

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

    New Mathematical Method Reveals Where Genes Switch On or Off New Mathematical Method Reveals Where Genes Switch On or Off "Compressed sensing" determines atomic-level energy potentials with accuracy approaching experimental measurement February 22, 2012 John Hules, JAHules@lbl.gov, +1 510 486 6008 Figure 1. Helix-turn-helix (HTH) proteins are the most widely distributed family of DNA-binding proteins, occurring in all biological kingdoms. This image shows a lambda repressor HTH

  17. New Spectroscopic Technique Reveals the Dynamics of Operating Battery

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

    Electrodes New Spectroscopic Technique Reveals the Dynamics of Operating Battery Electrodes New Spectroscopic Technique Reveals the Dynamics of Operating Battery Electrodes Print Wednesday, 29 January 2014 00:00 Developing high-performance batteries relies on material breakthroughs. During the past few years, various in situ characterization tools have been developed and have become indispensable in studying and the eventual optimization of battery materials. However, soft x-ray

  18. Secrets of the Motor That Drives Archaea Revealed

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

    Secrets of the Motor That Drives Archaea Revealed Secrets of the Motor That Drives Archaea Revealed Print Thursday, 14 February 2013 00:00 An international team led by John Tainer of the Life Sciences Division and Sonja-Verena Albers of the Max Planck Institute for Terrestrial Microbiology has solved the protein structure of the archaellum, the motor that propels motile species of Archaea (microorganisms), life's third domain. The Albers lab zeroed in on the crucial protein with genetics, and

  19. Study reveals urban smoke absorbs sunlight, exacerbating climate warming

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

    Study reveals urban smoke absorbs sunlight Study reveals urban smoke absorbs sunlight, exacerbating climate warming Cloaking urban areas and wildfire zones, tiny smoke particles suspended in the atmosphere have a sizeable effect on our climate. September 30, 2015 A new study by a science team led by Los Alamos National Laboratory stresses the importance of understanding mixed black and brown carbon in smoke emissions for climate models. The particulates found in urban smoke are especially prone

  20. Computer modeling reveals how surprisingly potent hepatitis C drug works

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

    Hepatitis C computer modeling Computer modeling reveals how surprisingly potent hepatitis C drug works A study reveals how daclatasvir targets one of its proteins and causes the fastest viral decline ever seen with anti-HCV drugs - within 12 hours of treatment. February 19, 2013 Los Alamos National Laboratory sits on top of a once-remote mesa in northern New Mexico with the Jemez mountains as a backdrop to research and innovation covering multi-disciplines from bioscience, sustainable energy

  1. Two types of luminescence blinking revealed by spectroelectrochemistry of

    Office of Scientific and Technical Information (OSTI)

    single quantum dots (Journal Article) | SciTech Connect Two types of luminescence blinking revealed by spectroelectrochemistry of single quantum dots Citation Details In-Document Search Title: Two types of luminescence blinking revealed by spectroelectrochemistry of single quantum dots Photoluminescence blinking-random switching between states of high (ON) and low (OFF) emissivities-is a universal property of molecular emitters found in dyes, polymers, biological molecules and artificial

  2. Transition from band insulator to Bose-Einstein-condensate superfluid and Mott state of cold Fermi gases with multiband effects in optical lattices

    SciTech Connect (OSTI)

    Watanabe, Ryota; Imada, Masatoshi

    2009-10-15

    We study two models realized by two-component Fermi gases loaded in optical lattices. We clarify that multiband effects inevitably caused by the optical lattices generate a rich structure, when the systems crossover from the region of weakly bound molecular bosons to the region of strongly bound atomic bosons. Here the crossover can be controlled by attractive fermion interaction. One of the present models is a case with attractive fermion interaction, where an insulator-superfluid transition takes place. The transition is characterized as the transition between a band insulator and a Bose-Einstein condensate superfluid state. Differing from the conventional Bardeen-Cooper-Schrieffer (BCS) superfluid transition, this transition shows unconventional properties. In contrast to the one-particle excitation gap scaled by the superfluid order parameter in the conventional BCS transition, because of the multiband effects, a large gap of one-particle density of states is retained all through the transition, although the superfluid order grows continuously from zero. A re-entrant transition with lowering temperature is another unconventionality. The other model is the case with coexisting attractive and repulsive interactions. Within a mean-field treatment, we find a new insulating state, an orbital ordered insulator. This insulator is one candidate for the Mott insulator of molecular bosons and is the first example that the orbital internal degrees of freedom of molecular bosons appears explicitly. Besides the emergence of a new phase, a coexisting phase also appears where superfluidity and an orbital order coexist just by doping holes or particles. The insulating and superfluid particles show differentiation in momentum space as in the high-T{sub c} cuprate superconductors.

  3. Non-thermal electron acceleration in low Mach number collisionless shocks. II. Firehose-mediated Fermi acceleration and its dependence on pre-shock conditions

    SciTech Connect (OSTI)

    Guo, Xinyi; Narayan, Ramesh; Sironi, Lorenzo

    2014-12-10

    Electron acceleration to non-thermal energies is known to occur in low Mach number (M{sub s} ? 5) shocks in galaxy clusters and solar flares, but the electron acceleration mechanism remains poorly understood. Using two-dimensional (2D) particle-in-cell (PIC) plasma simulations, we showed in Paper I that electrons are efficiently accelerated in low Mach number (M{sub s} = 3) quasi-perpendicular shocks via a Fermi-like process. The electrons bounce between the upstream region and the shock front, with each reflection at the shock resulting in energy gain via shock drift acceleration. The upstream scattering is provided by oblique magnetic waves that are self-generated by the electrons escaping ahead of the shock. In the present work, we employ additional 2D PIC simulations to address the nature of the upstream oblique waves. We find that the waves are generated by the shock-reflected electrons via the firehose instability, which is driven by an anisotropy in the electron velocity distribution. We systematically explore how the efficiency of wave generation and of electron acceleration depend on the magnetic field obliquity, the flow magnetization (or equivalently, the plasma beta), and the upstream electron temperature. We find that the mechanism works for shocks with high plasma beta (? 20) at nearly all magnetic field obliquities, and for electron temperatures in the range relevant for galaxy clusters. Our findings offer a natural solution to the conflict between the bright radio synchrotron emission observed from the outskirts of galaxy clusters and the low electron acceleration efficiency usually expected in low Mach number shocks.

  4. THE HELIOTAIL REVEALED BY THE INTERSTELLAR BOUNDARY EXPLORER

    SciTech Connect (OSTI)

    McComas, D. J.; Dayeh, M. A.; Livadiotis, G.; Funsten, H. O.; Schwadron, N. A.

    2013-07-10

    Recent combined observations from the first three years of Interstellar Boundary Explorer (IBEX) data allow us to examine the heliosphere's downwind region-the heliotail-for the first time. In contrast to a preliminary identification of a narrow ''offset heliotail'' structure, we find a broad slow solar wind plasma sheet crossing essentially the entire downwind side of the heliosphere at low to mid-latitudes, with fast wind tail regions to the north and south. The slow wind plasma sheet exhibits the steepest ENA spectra in the IBEX sky maps, appears as a two-lobed structure (lobes on the port and starboard sides), and is twisted in the sense of (but at a smaller angle than) the external magnetic field. The overall heliotail structure clearly demonstrates the intermediate nature of the heliosphere's interstellar interaction, where both the external dynamic and magnetic pressures strongly affect the heliosphere.

  5. New Model of Earth's Interior Reveals Clues to Hotspot Volcanoes

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

    New Model of Earth's Interior Reveals Clues to Hotspot Volcanoes New Model of Earth's Interior Reveals Clues to Hotspot Volcanoes October 29, 2013 Contact: Linda Vu, +1 510 495 2402, lvu@lbl.gov volcanic-hotspots1.jpg This 3D view of the top 1,000 kilometers of Earth's mantle beneath the central Pacific shows the relationship between seismically-slow "plumes" and channels imaged in the UC Berkeley study. Green cones on the ocean floor mark islands associated with "hotspot"

  6. Change of translational-rotational coupling in liquids revealed by

    Office of Scientific and Technical Information (OSTI)

    field-cycling {sup 1}H NMR (Journal Article) | SciTech Connect Change of translational-rotational coupling in liquids revealed by field-cycling {sup 1}H NMR Citation Details In-Document Search Title: Change of translational-rotational coupling in liquids revealed by field-cycling {sup 1}H NMR Applying the field-cycling nuclear magnetic resonance technique, the frequency dependence of the {sup 1}H spin-lattice relaxation rate, R{sub 1}(ω)=T{sub 1}{sup -1}(ω), is measured for propylene

  7. Skyrmion Behavior Revealed by Two X-Ray Studies

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

    Skyrmion Behavior Revealed by Two X-Ray Studies Skyrmion Behavior Revealed by Two X-Ray Studies Print Thursday, 11 September 2014 15:18 Sometimes, the spins in a magnetic material will form tiny swirls that can move around like particles. The spins themselves stay put-it's the pattern that moves. These quasiparticles have been dubbed "skyrmions," after British physicist Tony Skyrme, who described their mathematics in a series of papers in the early 1960s. Now, over 50 years later,

  8. Unusual light in dark space revealed by Los Alamos, NASA

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

    Unusual light in dark space revealed by Los Alamos, NASA Unusual light in dark space revealed by Los Alamos, NASA By looking at the dark spaces between visible galaxies and stars the NASA/JPL CIBER sounding rocket experiment has produced data that could redefine what constitutes a galaxy. November 7, 2014 Paul Johnson The optical array on the CIBER instrument, image from NASA. Contact Kevin Roark Communications Office (505) 665-9202 Email "We think stars are being scattered out into space

  9. New DOE Report Reveals Significant Growth in Distributed Wind | Department

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

    of Energy DOE Report Reveals Significant Growth in Distributed Wind New DOE Report Reveals Significant Growth in Distributed Wind August 1, 2013 - 2:25pm Addthis This is an excerpt from the Second Quarter 2013 edition of the Wind Program R&D Newsletter. Washington, D.C.-This August, the U.S. Department of Energy (DOE) released the first annual market report on wind technologies used in distributed applications compiled through a collaborative effort by DOE's Pacific Northwest National

  10. DNA Duplication Revealed in New Beginnings | Department of Energy

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

    DNA Duplication Revealed in New Beginnings DNA Duplication Revealed in New Beginnings April 3, 2012 - 9:36am Addthis The DNA replication origin recognition complex (ORC) is a six-protein machine with a slightly twisted half-ring structure (yellow). ORC is proposed to wrap around and bend approximately 70 base pairs of double stranded DNA (red and blue). When a replication initiator Cdc6 (green) joins ORC, the partial ring is now complete and ready to load another protein onto the DNA. This last

  11. Combined methods reveal how water moves in trees

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

    April » Combined methods reveal how water moves in trees Combined methods reveal how water moves in trees Water use by trees is a key part of the hydrological process linking soil to climate and local weather June 7, 2015 Photograph of the ULF-NMR and neutron imaging experiment. Photograph of the ULF-NMR and neutron imaging experiment: the experiment is conducted under a special growth lamp to induce stomatal opening. An LED lamp (no magnetic noise and heat produced) provides a high density of

  12. An Iridate with Fermi Arcs

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

    (Univ. of Michigan); and B.J Kim (Argonne National Laboratory, Univ. of Michigan, and Max Planck Institute for Solid State Research). Research funding: National Science...

  13. New Spectroscopic Technique Reveals the Dynamics of Operating Battery

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

    Electrodes Spectroscopic Technique Reveals the Dynamics of Operating Battery Electrodes Print Developing high-performance batteries relies on material breakthroughs. During the past few years, various in situ characterization tools have been developed and have become indispensable in studying and the eventual optimization of battery materials. However, soft x-ray spectroscopy, one of the most sensitive probes of electronic states, has been mainly limited to ex situ experiments for battery

  14. New Spectroscopic Technique Reveals the Dynamics of Operating Battery

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

    Electrodes New Spectroscopic Technique Reveals the Dynamics of Operating Battery Electrodes Print Developing high-performance batteries relies on material breakthroughs. During the past few years, various in situ characterization tools have been developed and have become indispensable in studying and the eventual optimization of battery materials. However, soft x-ray spectroscopy, one of the most sensitive probes of electronic states, has been mainly limited to ex situ experiments for

  15. New Spectroscopic Technique Reveals the Dynamics of Operating Battery

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

    Electrodes New Spectroscopic Technique Reveals the Dynamics of Operating Battery Electrodes Print Developing high-performance batteries relies on material breakthroughs. During the past few years, various in situ characterization tools have been developed and have become indispensable in studying and the eventual optimization of battery materials. However, soft x-ray spectroscopy, one of the most sensitive probes of electronic states, has been mainly limited to ex situ experiments for

  16. ALS Capabilities Reveal How Like Can Attract Like

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

    ALS Capabilities Reveal How Like Can Attract Like Print A Berkeley Lab research team working at the ALS has observed an unusual pairing that seems to go against a universal scientific truth-that opposite charges attract and like charges repel. Led by Berkeley Lab chemist Richard Saykally and theorist David Prendergast, researchers demonstrated that, when hydrated in water, positively charged ions (cations) can actually pair up with one another. A New Law of Water Affinities Late 19th century

  17. ALS Capabilities Reveal How Like Can Attract Like

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

    ALS Capabilities Reveal How Like Can Attract Like Print A Berkeley Lab research team working at the ALS has observed an unusual pairing that seems to go against a universal scientific truth-that opposite charges attract and like charges repel. Led by Berkeley Lab chemist Richard Saykally and theorist David Prendergast, researchers demonstrated that, when hydrated in water, positively charged ions (cations) can actually pair up with one another. A New Law of Water Affinities Late 19th century

  18. ALS Capabilities Reveal Multiple Functions of Ebola Virus

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

    ALS Capabilities Reveal Multiple Functions of Ebola Virus Print A central dogma of molecular biology is that a protein's sequence dictates its fold, and the fold dictates its function. Scientists typically expect that a protein has a singular structure (with some conformational variation), and that when an experimental structure is solved, it can used to understand the known biological function(s) of the protein. Recently, researchers used beamline capabilities at the ALS to demonstrate that a

  19. Molecular Structure of Water at Gold Electrodes Revealed

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

    Molecular Structure of Water at Gold Electrodes Revealed Print The structure of liquid water has been intensely studied, but until recently, it has not been clear what happens to it when a surface is introduced. ALS researchers have now made a first-ever observation of the molecular structure of liquid water at a gold surface under different charging conditions. This marks the first time that the scientific community has shown such high sensitivity in an in-situ environment under working

  20. Molecular Structure of Water at Gold Electrodes Revealed

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

    Molecular Structure of Water at Gold Electrodes Revealed Print The structure of liquid water has been intensely studied, but until recently, it has not been clear what happens to it when a surface is introduced. ALS researchers have now made a first-ever observation of the molecular structure of liquid water at a gold surface under different charging conditions. This marks the first time that the scientific community has shown such high sensitivity in an in-situ environment under working

  1. Molecular Structure of Water at Gold Electrodes Revealed

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

    Molecular Structure of Water at Gold Electrodes Revealed Print The structure of liquid water has been intensely studied, but until recently, it has not been clear what happens to it when a surface is introduced. ALS researchers have now made a first-ever observation of the molecular structure of liquid water at a gold surface under different charging conditions. This marks the first time that the scientific community has shown such high sensitivity in an in-situ environment under working

  2. Molecular Structure of Water at Gold Electrodes Revealed

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

    Molecular Structure of Water at Gold Electrodes Revealed Print The structure of liquid water has been intensely studied, but until recently, it has not been clear what happens to it when a surface is introduced. ALS researchers have now made a first-ever observation of the molecular structure of liquid water at a gold surface under different charging conditions. This marks the first time that the scientific community has shown such high sensitivity in an in-situ environment under working

  3. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

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

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  4. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

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

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  5. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

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

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  6. Quantum Dimension of Photosynthesis Revealed by Angular Resolved Coherent

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

    Imaging | MIT-Harvard Center for Excitonics Dimension of Photosynthesis Revealed by Angular Resolved Coherent Imaging September 29, 2009 at 3pm/36-428 Ian Mercer Department of Physics, University College Dublin mercer abstract: Understanding the role of coherent electronic motion is expected to resolve general questions of importance in macromolecular energy transfer, in nature and in devices. Significant progress has been made using coherent optical four wave-mixing, however the

  7. Jets reveal cerium's shocked strength | Argonne National Laboratory

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

    Jets reveal cerium's shocked strength By Vic Comello * January 27, 2016 Tweet EmailPrint Recent synchrotron advances and the development of dynamic compression platforms have created the ability to investigate extreme states of matter on short timescales at X-ray beamlines using shockwaves generated by impact systems. That's how scientists learned that surface protrusions called "jets," formed after shockwaves passed through cerium metal, could provide insight into the yield stress of

  8. Archaeopteryx Feathers and Bone Chemistry Fully Revealed via Synchrotron

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

    Imaging Archaeopteryx Feathers and Bone Chemistry Fully Revealed via Synchrotron Imaging Archaeopteryx specimens are important but extremely rare fossils. Due to their possession of both reptilian (jaws with teeth, long bony tail) and avian (feathered wings) characters, Archaeopteryx has been crucial in the development of Darwinian evolution. Despite their importance, no Archaeopteryx specimen has ever been chemically analyzed. This in large part may be explained by the analytical obstacles

  9. ALS Capabilities Reveal How Like Can Attract Like

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

    ALS Capabilities Reveal How Like Can Attract Like Print A Berkeley Lab research team working at the ALS has observed an unusual pairing that seems to go against a universal scientific truth-that opposite charges attract and like charges repel. Led by Berkeley Lab chemist Richard Saykally and theorist David Prendergast, researchers demonstrated that, when hydrated in water, positively charged ions (cations) can actually pair up with one another. A New Law of Water Affinities Late 19th century

  10. ALS Capabilities Reveal How Like Can Attract Like

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

    ALS Capabilities Reveal How Like Can Attract Like Print A Berkeley Lab research team working at the ALS has observed an unusual pairing that seems to go against a universal scientific truth-that opposite charges attract and like charges repel. Led by Berkeley Lab chemist Richard Saykally and theorist David Prendergast, researchers demonstrated that, when hydrated in water, positively charged ions (cations) can actually pair up with one another. A New Law of Water Affinities Late 19th century

  11. ALS Capabilities Reveal How Like Can Attract Like

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

    ALS Capabilities Reveal How Like Can Attract Like Print A Berkeley Lab research team working at the ALS has observed an unusual pairing that seems to go against a universal scientific truth-that opposite charges attract and like charges repel. Led by Berkeley Lab chemist Richard Saykally and theorist David Prendergast, researchers demonstrated that, when hydrated in water, positively charged ions (cations) can actually pair up with one another. A New Law of Water Affinities Late 19th century

  12. ALS Capabilities Reveal How Like Can Attract Like

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

    ALS Capabilities Reveal How Like Can Attract Like Print A Berkeley Lab research team working at the ALS has observed an unusual pairing that seems to go against a universal scientific truth-that opposite charges attract and like charges repel. Led by Berkeley Lab chemist Richard Saykally and theorist David Prendergast, researchers demonstrated that, when hydrated in water, positively charged ions (cations) can actually pair up with one another. A New Law of Water Affinities Late 19th century

  13. ALS Capabilities Reveal How Like Can Attract Like

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

    ALS Capabilities Reveal How Like Can Attract Like Print A Berkeley Lab research team working at the ALS has observed an unusual pairing that seems to go against a universal scientific truth-that opposite charges attract and like charges repel. Led by Berkeley Lab chemist Richard Saykally and theorist David Prendergast, researchers demonstrated that, when hydrated in water, positively charged ions (cations) can actually pair up with one another. A New Law of Water Affinities Late 19th century

  14. ALS Capabilities Reveal Multiple Functions of Ebola Virus

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

    ALS Capabilities Reveal Multiple Functions of Ebola Virus Print A central dogma of molecular biology is that a protein's sequence dictates its fold, and the fold dictates its function. Scientists typically expect that a protein has a singular structure (with some conformational variation), and that when an experimental structure is solved, it can used to understand the known biological function(s) of the protein. Recently, researchers used beamline capabilities at the ALS to demonstrate that a

  15. ALS Capabilities Reveal Multiple Functions of Ebola Virus

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

    ALS Capabilities Reveal Multiple Functions of Ebola Virus Print A central dogma of molecular biology is that a protein's sequence dictates its fold, and the fold dictates its function. Scientists typically expect that a protein has a singular structure (with some conformational variation), and that when an experimental structure is solved, it can used to understand the known biological function(s) of the protein. Recently, researchers used beamline capabilities at the ALS to demonstrate that a

  16. ALS Capabilities Reveal Multiple Functions of Ebola Virus

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

    ALS Capabilities Reveal Multiple Functions of Ebola Virus Print A central dogma of molecular biology is that a protein's sequence dictates its fold, and the fold dictates its function. Scientists typically expect that a protein has a singular structure (with some conformational variation), and that when an experimental structure is solved, it can used to understand the known biological function(s) of the protein. Recently, researchers used beamline capabilities at the ALS to demonstrate that a

  17. Plasma Turbulence Simulations Reveal Promising Insight for Fusion Energy |

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

    Princeton Plasma Physics Lab Plasma Turbulence Simulations Reveal Promising Insight for Fusion Energy By Argonne National Laboratory March 31, 2014 Tweet Widget Google Plus One Share on Facebook Simulation of microturbulence in a tokamak fusion device. (Credit: Chad Jones and Kwan-Liu Ma, University of California, Davis; Stephane Ethier, Princeton Plasma Physics Laboratory) Simulation of microturbulence in a tokamak fusion device. (Credit: Chad Jones and Kwan-Liu Ma, University of

  18. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

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

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  19. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

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

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  20. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

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

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  1. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

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

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  2. Polarized X-Rays Reveal Molecular Alignment in Printed Electronics

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

    Polarized X-Rays Reveal Molecular Alignment in Printed Electronics Print The printing of electronic devices using giant roll-to-roll presses or inkjet-style printers has recently been made possible by the development of solution-processable organic materials with optoelectronic properties. Organic light-emitting diodes (OLEDs) are already being produced commercially, and sensors, organic thin-film transistors (OTFTs), and organic photovoltaics (OPVs) are also well on their way to commercial

  3. Molecular Structure of Water at Gold Electrodes Revealed

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

    Molecular Structure of Water at Gold Electrodes Revealed Print The structure of liquid water has been intensely studied, but until recently, it has not been clear what happens to it when a surface is introduced. ALS researchers have now made a first-ever observation of the molecular structure of liquid water at a gold surface under different charging conditions. This marks the first time that the scientific community has shown such high sensitivity in an in-situ environment under working

  4. Molecular Structure of Water at Gold Electrodes Revealed

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

    Molecular Structure of Water at Gold Electrodes Revealed Print The structure of liquid water has been intensely studied, but until recently, it has not been clear what happens to it when a surface is introduced. ALS researchers have now made a first-ever observation of the molecular structure of liquid water at a gold surface under different charging conditions. This marks the first time that the scientific community has shown such high sensitivity in an in-situ environment under working

  5. NREL Reveals Potential for Capturing Waste Heat via Nanotubes - News

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

    Releases | NREL Reveals Potential for Capturing Waste Heat via Nanotubes April 4, 2016 A finely tuned carbon nanotube thin film has the potential to act as a thermoelectric power generator that captures and uses waste heat, according to researchers at the Energy Department's National Renewable Energy Laboratory (NREL). The research could help guide the manufacture of thermoelectric devices based on either single-walled carbon nanotube (SWCNT) films or composites containing these nanotubes.

  6. Two Studies Reveal Details of Lithium-Battery Function

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

    Two Studies Reveal Details of Lithium-Battery Function Print Our way of life is deeply intertwined with battery technologies that have enabled a mobile revolution powering cell phones, laptops, medical devices, and cars. As conventional lithium-ion batteries approach their theoretical energy-storage limits, new technologies are emerging to address the long-term energy-storage improvements needed for mobile systems, electric vehicles in particular. Battery performance depends on the dynamics of

  7. Two Studies Reveal Details of Lithium-Battery Function

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

    Two Studies Reveal Details of Lithium-Battery Function Print Our way of life is deeply intertwined with battery technologies that have enabled a mobile revolution powering cell phones, laptops, medical devices, and cars. As conventional lithium-ion batteries approach their theoretical energy-storage limits, new technologies are emerging to address the long-term energy-storage improvements needed for mobile systems, electric vehicles in particular. Battery performance depends on the dynamics of

  8. Two Studies Reveal Details of Lithium-Battery Function

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

    Two Studies Reveal Details of Lithium-Battery Function Print Our way of life is deeply intertwined with battery technologies that have enabled a mobile revolution powering cell phones, laptops, medical devices, and cars. As conventional lithium-ion batteries approach their theoretical energy-storage limits, new technologies are emerging to address the long-term energy-storage improvements needed for mobile systems, electric vehicles in particular. Battery performance depends on the dynamics of

  9. Two Studies Reveal Details of Lithium-Battery Function

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

    Two Studies Reveal Details of Lithium-Battery Function Print Our way of life is deeply intertwined with battery technologies that have enabled a mobile revolution powering cell phones, laptops, medical devices, and cars. As conventional lithium-ion batteries approach their theoretical energy-storage limits, new technologies are emerging to address the long-term energy-storage improvements needed for mobile systems, electric vehicles in particular. Battery performance depends on the dynamics of

  10. Website Reveals Early Lessons in Electric Vehicle Deployment - News

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

    Website Policies / Important Links Website Policies / Important Links Javascript Not Enabled OSTI Security Website Policies and Important Links Releases | NREL

    Website Reveals Early Lessons in Electric Vehicle Deployment New web page is an online blueprint for community leaders February 22, 2011 Cities and states have new blueprints to follow as they prepare for the arrival of plug-in electric vehicles. The U.S. Department of Energy's (DOE) National Renewable Energy Laboratory (NREL) just

  11. New Spectroscopic Technique Reveals the Dynamics of Operating Battery

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

    Electrodes New Spectroscopic Technique Reveals the Dynamics of Operating Battery Electrodes Print Developing high-performance batteries relies on material breakthroughs. During the past few years, various in situ characterization tools have been developed and have become indispensable in studying and the eventual optimization of battery materials. However, soft x-ray spectroscopy, one of the most sensitive probes of electronic states, has been mainly limited to ex situ experiments for

  12. New Spectroscopic Technique Reveals the Dynamics of Operating Battery

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

    Electrodes New Spectroscopic Technique Reveals the Dynamics of Operating Battery Electrodes Print Developing high-performance batteries relies on material breakthroughs. During the past few years, various in situ characterization tools have been developed and have become indispensable in studying and the eventual optimization of battery materials. However, soft x-ray spectroscopy, one of the most sensitive probes of electronic states, has been mainly limited to ex situ experiments for

  13. New Spectroscopic Technique Reveals the Dynamics of Operating Battery

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

    Electrodes New Spectroscopic Technique Reveals the Dynamics of Operating Battery Electrodes Print Developing high-performance batteries relies on material breakthroughs. During the past few years, various in situ characterization tools have been developed and have become indispensable in studying and the eventual optimization of battery materials. However, soft x-ray spectroscopy, one of the most sensitive probes of electronic states, has been mainly limited to ex situ experiments for

  14. New Spectroscopic Technique Reveals the Dynamics of Operating Battery

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

    Electrodes New Spectroscopic Technique Reveals the Dynamics of Operating Battery Electrodes Print Developing high-performance batteries relies on material breakthroughs. During the past few years, various in situ characterization tools have been developed and have become indispensable in studying and the eventual optimization of battery materials. However, soft x-ray spectroscopy, one of the most sensitive probes of electronic states, has been mainly limited to ex situ experiments for

  15. Electrolyte Genome Reveals New Instability Mechanism in Mg Electrolytes -

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

    Joint Center for Energy Storage Research February 10, 2015, Research Highlights Electrolyte Genome Reveals New Instability Mechanism in Mg Electrolytes (Top) The Mg salt and solvent combinations simulated for solvation shell structures and dynamics (Bottom) The TFSI- decomposition mechanism triggered by partial reduction of Mg2+ ->Mg+. This mechanism consumes anion, disrupts the deposition of Mg0 on the anode and may deposit anion fragments on the anode. Scientific Achievement Simulations

  16. Structures of GRP94-Nucleotide Complexes Reveal Mechanistic Differences

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

    between the Hsp90 Chaperones Structures of GRP94-Nucleotide Complexes Reveal Mechanistic Differences between the Hsp90 Chaperones Life depends on the biochemical activity of the thousands of proteins that inhabit and decorate the surface of every one of our cells. Proteins themselves, although simple linear combinations of the twenty amino acids, derive their remarkable properties from the complex three-dimensional structures into which they fold. In this way, enzyme active sites are

  17. NREL: Technology Deployment - Resource Maps for Taller Towers Reveal New

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

    Areas for Wind Project Development Resource Maps for Taller Towers Reveal New Areas for Wind Project Development News Mapping the Frontier of New Wind Power Potential Publications Southeastern Wind Coalition fact sheets Southeast Wind Energy Fact Sheet Enabling Wind Power Nationwide Wind Vision: A New Era for Wind Power in the United States Sponsors AWS Truepower Southeastern Wind Coalition Key Partners U.S. Department of Energy Contact Ian Baring-Gould, 303-384-7021 A picture of a tall wind

  18. Skyrmion Behavior Revealed by Two X-Ray Studies

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

    Skyrmion Behavior Revealed by Two X-Ray Studies Print Sometimes, the spins in a magnetic material will form tiny swirls that can move around like particles. The spins themselves stay put-it's the pattern that moves. These quasiparticles have been dubbed "skyrmions," after British physicist Tony Skyrme, who described their mathematics in a series of papers in the early 1960s. Now, over 50 years later, scientists are intrigued by the possibility that skyrmions could play a key role in

  19. Skyrmion Behavior Revealed by Two X-Ray Studies

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

    Skyrmion Behavior Revealed by Two X-Ray Studies Print Sometimes, the spins in a magnetic material will form tiny swirls that can move around like particles. The spins themselves stay put-it's the pattern that moves. These quasiparticles have been dubbed "skyrmions," after British physicist Tony Skyrme, who described their mathematics in a series of papers in the early 1960s. Now, over 50 years later, scientists are intrigued by the possibility that skyrmions could play a key role in

  20. Skyrmion Behavior Revealed by Two X-Ray Studies

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

    Skyrmion Behavior Revealed by Two X-Ray Studies Print Sometimes, the spins in a magnetic material will form tiny swirls that can move around like particles. The spins themselves stay put-it's the pattern that moves. These quasiparticles have been dubbed "skyrmions," after British physicist Tony Skyrme, who described their mathematics in a series of papers in the early 1960s. Now, over 50 years later, scientists are intrigued by the possibility that skyrmions could play a key role in

  1. Skyrmion Behavior Revealed by Two X-Ray Studies

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

    Skyrmion Behavior Revealed by Two X-Ray Studies Print Sometimes, the spins in a magnetic material will form tiny swirls that can move around like particles. The spins themselves stay put-it's the pattern that moves. These quasiparticles have been dubbed "skyrmions," after British physicist Tony Skyrme, who described their mathematics in a series of papers in the early 1960s. Now, over 50 years later, scientists are intrigued by the possibility that skyrmions could play a key role in

  2. Skyrmion Behavior Revealed by Two X-Ray Studies

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

    Skyrmion Behavior Revealed by Two X-Ray Studies Print Sometimes, the spins in a magnetic material will form tiny swirls that can move around like particles. The spins themselves stay put-it's the pattern that moves. These quasiparticles have been dubbed "skyrmions," after British physicist Tony Skyrme, who described their mathematics in a series of papers in the early 1960s. Now, over 50 years later, scientists are intrigued by the possibility that skyrmions could play a key role in

  3. Skyrmion Behavior Revealed by Two X-Ray Studies

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

    Skyrmion Behavior Revealed by Two X-Ray Studies Print Sometimes, the spins in a magnetic material will form tiny swirls that can move around like particles. The spins themselves stay put-it's the pattern that moves. These quasiparticles have been dubbed "skyrmions," after British physicist Tony Skyrme, who described their mathematics in a series of papers in the early 1960s. Now, over 50 years later, scientists are intrigued by the possibility that skyrmions could play a key role in

  4. Skyrmion Behavior Revealed by Two X-Ray Studies

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

    Skyrmion Behavior Revealed by Two X-Ray Studies Print Sometimes, the spins in a magnetic material will form tiny swirls that can move around like particles. The spins themselves stay put-it's the pattern that moves. These quasiparticles have been dubbed "skyrmions," after British physicist Tony Skyrme, who described their mathematics in a series of papers in the early 1960s. Now, over 50 years later, scientists are intrigued by the possibility that skyrmions could play a key role in

  5. Direct visualization reveals kinetics of meiotic chromosome synapsis

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

    Rog, Ofer; Dernburg, Abby  F.

    2015-03-17

    The synaptonemal complex (SC) is a conserved protein complex that stabilizes interactions along homologous chromosomes (homologs) during meiosis. The SC regulates genetic exchanges between homologs, thereby enabling reductional division and the production of haploid gametes. Here, we directly observe SC assembly (synapsis) by optimizing methods for long-term fluorescence recording in C. elegans. We report that synapsis initiates independently on each chromosome pair at or near pairing centers—specialized regions required for homolog associations. Once initiated, the SC extends rapidly and mostly irreversibly to chromosome ends. Quantitation of SC initiation frequencies and extension rates reveals that initiation is a rate-limiting step inmore » homolog interactions. Eliminating the dynein-driven chromosome movements that accompany synapsis severely retards SC extension, revealing a new role for these conserved motions. This work provides the first opportunity to directly observe and quantify key aspects of meiotic chromosome interactions and will enable future in vivo analysis of germline processes.« less

  6. Macrophage characteristics of stem cells revealed by transcriptome profiling

    SciTech Connect (OSTI)

    Charriere, Guillaume M.; Cousin, Beatrice; Arnaud, Emmanuelle; Saillan-Barreau, Corinne; Andre, Mireille; Massoudi, Ali; Dani, Christian; Penicaud, Luc; Casteilla, Louis . E-mail: casteil@toulouse.inserm.fr

    2006-10-15

    We previously showed that the phenotypes of adipocyte progenitors and macrophages were close. Using functional analyses and microarray technology, we first tested whether this intriguing relationship was specific to adipocyte progenitors or could be shared with other progenitors. Measurements of phagocytic activity and gene profiling analysis of different progenitor cells revealed that the latter hypothesis should be retained. These results encouraged us to pursue and to confirm our analysis with a gold-standard stem cell population, embryonic stem cells or ESC. The transcriptomic profiles of ESC and macrophages were clustered together, unlike differentiated ESC. In addition, undifferentiated ESC displayed higher phagocytic activity than other progenitors, and they could phagocytoze apoptotic bodies. These data suggest that progenitors and stem cells share some characteristics of macrophages. This opens new perspectives on understanding stem cell phenotype and functionalities such as a putative role of stem cells in tissue remodeling by discarding dead cells but also their immunomodulation or fusion properties.

  7. Physical Principles of Skeletal Minerals Revealed with Spectromicroscopy

    ScienceCinema (OSTI)

    Gilbert, Pupa [U of Wisconsin-Madison, Wisconsin, United States

    2010-01-08

    Skeletal elements of marine and terrestrial organisms have the most fascinating nano-to-macro-structures, attracting the attention of physicists, biologists, chemists, and materials scientists. Using X-PEEM spectromicroscopy we revealed some of the fundamental mechanisms leading to the formation of these biominerals. Specifically, we addressed the following questions and provided the answers: 1Q) How do teeth, bones, and echinoderm and mollusk shells acquire their unusual, curved and complex morphology, if they are composed of single crystals? 1A) Via amorphous precursor phases; 2Q) How does crystallinity propagate through the amorophous precursor phases in sea urchin spicules and teeth? 2A) By secondary nucleation, following random walk patterns; 3Q) How does iridescent mother-of-pearl become ordered? 3A) Gradually, through a kinetic mechanisms in which fastest growing single-crystals win the competition for space, thus end up being approximately co-oriented.

  8. Dramatic changes in electronic structure revealed by fractionally charged nuclei

    SciTech Connect (OSTI)

    Cohen, Aron J.; Mori-Snchez, Paula

    2014-01-28

    Discontinuous changes in the electronic structure upon infinitesimal changes to the Hamiltonian are demonstrated. These are revealed in one and two electron molecular systems by full configuration interaction (FCI) calculations when the realm of the nuclear charge is extended to be fractional. FCI electron densities in these systems show dramatic changes in real space and illustrate the transfer, hopping, and removal of electrons. This is due to the particle nature of electrons seen in stretched systems and is a manifestation of an energy derivative discontinuity at constant number of electrons. Dramatic errors of density functional theory densities are seen in real space as this physics is missing from currently used approximations. The movements of electrons in these simple systems encapsulate those in real physical processes, from chemical reactions to electron transport and pose a great challenge for the development of new electronic structure methods.

  9. Enhancement of spin polarization via Fermi level tuning in Co{sub 2}MnSn{sub 1−x}Sb{sub x} (x = 0, 0.25. 0.5, 0.75, 1) Heusler alloys

    SciTech Connect (OSTI)

    Singh, Mukhtiyar Thakur, Jyoti; Kashyap, Manish K.; Saini, Hardev S.

    2014-04-24

    Full potential approach has been employed to tune Fermi level in Co{sub 2}MnSn{sub 1−x}Sb{sub x} (x = 0, 0.25, 0.5, 0.75, 1) Heulser alloys for enhancement of spin polarization and finding signature of half metallicity. Present density functional theory (DFT) based calculation indicates that stoichoimetric Heusler alloy, Co{sub 2}MnSn is not a half-metallic ferromagnet but the doping of Sb in it results in the shifting of E{sup F} in well-defined energy gap which leads the 100% spin polarization in the resultant alloys. The magnetism in present alloys is governed by localized moment on Mn atom mainly. The tuning of half-metallicity using doping can be proved as an ideal technique to search the new materials which can accomplish the need of spintronics.

  10. Crystallographic and spectroscopic snapshots reveal a dehydrogenase in action

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

    Huo, Lu; Davis, Ian; Liu, Fange; Andi, Babak; Esaki, Shingo; Iwaki, Hiroaki; Hasegawa, Yoshie; Orville, Allen M.; Liu, Aimin

    2015-01-07

    Aldehydes are ubiquitous intermediates in metabolic pathways and their innate reactivity can often make them quite unstable. There are several aldehydic intermediates in the metabolic pathway for tryptophan degradation that can decay into neuroactive compounds that have been associated with numerous neurological diseases. An enzyme of this pathway, 2-aminomuconate-6-semialdehyde dehydrogenase, is responsible for ‘disarming’ the final aldehydic intermediate. Here we show the crystal structures of a bacterial analogue enzyme in five catalytically relevant forms: resting state, one binary and two ternary complexes, and a covalent, thioacyl intermediate. We also report the crystal structures of a tetrahedral, thiohemiacetal intermediate, a thioacylmore » intermediate and an NAD+-bound complex from an active site mutant. These covalent intermediates are characterized by single-crystal and solution-state electronic absorption spectroscopy. The crystal structures reveal that the substrate undergoes an E/Z isomerization at the enzyme active site before an sp3-to-sp2 transition during enzyme-mediated oxidation.« less

  11. Ternary structure reveals mechanism of a membrane diacylglycerol kinase

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

    Li, Dianfan; Stansfeld, Phillip J.; Sansom, Mark S. P.; Keogh, Aaron; Vogeley, Lutz; Howe, Nicole; Lyons, Joseph A.; Aragao, David; Fromme, Petra; Fromme, Raimund; et al

    2015-12-17

    Diacylglycerol kinase catalyses the ATP-dependent conversion of diacylglycerol to phosphatidic acid in the plasma membrane of Escherichia coli. The small size of this integral membrane trimer, which has 121 residues per subunit, means that available protein must be used economically to craft three catalytic and substrate-binding sites centred about the membrane/cytosol interface. How nature has accomplished this extraordinary feat is revealed here in a crystal structure of the kinase captured as a ternary complex with bound lipid substrate and an ATP analogue. Residues, identified as essential for activity by mutagenesis, decorate the active site and are rationalized by the ternarymore » structure. The γ-phosphate of the ATP analogue is positioned for direct transfer to the primary hydroxyl of the lipid whose acyl chain is in the membrane. A catalytic mechanism for this unique enzyme is proposed. As a result, the active site architecture shows clear evidence of having arisen by convergent evolution.« less

  12. Algal genomes reveal evolutionary mosaicism and the fate of nucleomorphs

    SciTech Connect (OSTI)

    Curtis, Bruce A.; Tanifuji, Goro; Burki, Fabien; Gruber, Ansgar; Irimia, Manuuel; Maruyama, Shinichiro; Arias, Maria C.; Ball, Steven G.; Gile, Gillian H.; Hirakawa, Yoshihisa; Hopkins, Julia F.; Kuo, Alan; Rensing, Stefan A.; Schmutz, Jeremy; Symeonidi, Aikaterini; Elias, Marek; Eveleigh, Robert J. M.; Herman, Emily K.; Klute, Mary J.; Nakayama, Takuro; Obornik, Miroslav; Reyes-Prieto, Adrian; Armbrust, E. Virginia; Aves, Stephen J.; Beiko, Robert G.; Coutinho, Pedro; Dacks, Joel B.; Durnford, Dion G.; Fast, Naomi M.; Green, Beverley R.; Grisdale, Cameron J.; Hempel, Franziska; Henrissat, Bernard; Hoppner, Marc P.; Ishida, Ken-Ichiro; Kim, Eunsoo; Koreny, Ludek; Kroth, Peter G.; Liu, Yuan; Malik, Shehre-Banoo; Maier, Uwe G.; McRose, Darcy; Mock, Thomas; Neilson, Jonathan A. D.; Onodera, Naoko T.; Poole, Anthony M.; Pritham, Ellen J.; Richards, Thomas A.; Rocap, Gabrielle; Roy, Scott W.; Sarai, Chihiro; Schaack, Sarah; Shirato, Shu; Slamovits, Claudio H.; Spencer, Davie F.; Suzuki, Shigekatsu; Worden, Alexandra Z.; Zauner, Stefan; Barry, Kerrie; Bell, Callum; Bharti, Arvind K.; Crow, John A.; Grimwood, Jane; Kramer, Robin; Lindquist, Erika; Lucas, Susan; Salamov, Asaf; McFadden, Geoffrey I.; Lane, Christopher E.; Keeling, Patrick J.; Gray, Michael W.; Grigoriev, Igor V.; Archibald, John M.

    2012-08-10

    Cryptophyte and chlorarachniophyte algae are transitional forms in the widespread secondary endosymbiotic acquisition of photosynthesis by engulfment of eukaryotic algae. Unlike most secondary plastid-bearing algae, miniaturized versions of the endosymbiont nuclei (nucleomorphs) persist in cryptophytes and chlorarachniophytes. To determine why, and to address other fundamental questions about eukaryote eukaryote endosymbiosis, we sequenced the nuclear genomes of the cryptophyte Guillardia theta and the chlorarachniophyte Bigelowiella natans. Both genomes have 21,000 protein genes and are intron rich, and B. natans exhibits unprecedented alternative splicing for a single-celled organism. Phylogenomic analyses and subcellular targeting predictions reveal extensive genetic and biochemical mosaicism, with both host- and endosymbiont-derived genes servicing the mitochondrion, the host cell cytosol, the plastid and the remnant endosymbiont cytosol of both algae. Mitochondrion-to-nucleus gene transfer still occurs in both organisms but plastid-to-nucleus and nucleomorph-to-nucleus transfers do not, which explains why a small residue of essential genes remains locked in each nucleomorph.

  13. Crystallographic and spectroscopic snapshots reveal a dehydrogenase in action

    SciTech Connect (OSTI)

    Huo, Lu; Davis, Ian; Liu, Fange; Andi, Babak; Esaki, Shingo; Iwaki, Hiroaki; Hasegawa, Yoshie; Orville, Allen M.; Liu, Aimin

    2015-01-07

    Aldehydes are ubiquitous intermediates in metabolic pathways and their innate reactivity can often make them quite unstable. There are several aldehydic intermediates in the metabolic pathway for tryptophan degradation that can decay into neuroactive compounds that have been associated with numerous neurological diseases. An enzyme of this pathway, 2-aminomuconate-6-semialdehyde dehydrogenase, is responsible for ‘disarming’ the final aldehydic intermediate. Here we show the crystal structures of a bacterial analogue enzyme in five catalytically relevant forms: resting state, one binary and two ternary complexes, and a covalent, thioacyl intermediate. We also report the crystal structures of a tetrahedral, thiohemiacetal intermediate, a thioacyl intermediate and an NAD+-bound complex from an active site mutant. These covalent intermediates are characterized by single-crystal and solution-state electronic absorption spectroscopy. The crystal structures reveal that the substrate undergoes an E/Z isomerization at the enzyme active site before an sp3-to-sp2 transition during enzyme-mediated oxidation.

  14. Structure of DNA-Bound FEN1 Reveals Mechanism of Action

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

    Structure of DNA-Bound FEN1 Reveals Mechanism of Action Structure of DNA-Bound FEN1 Reveals Mechanism of Action Print Tuesday, 24 January 2012 11:30 DNA replication is a critical...

  15. Structure of a Bud6/Actin Complex Reveals a Novel WH2-like Actin...

    Office of Scientific and Technical Information (OSTI)

    of a Bud6Actin Complex Reveals a Novel WH2-like Actin Monomer Recruitment Motif Citation Details In-Document Search Title: Structure of a Bud6Actin Complex Reveals a Novel ...

  16. Next Generation Lunch: Revealing the World's First 3D Printed Car (text

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

    version) | Department of Energy Next Generation Lunch: Revealing the World's First 3D Printed Car (text version) Next Generation Lunch: Revealing the World's First 3D Printed Car (text version) Below is the text version for the Next Generation Lunch: Revealing the World's First 3D Printed Car Video. FILE NAME: AEMC_09172014_luncheonaddress_nextgeneration SPEAKER: Ladies and gentleman, welcome and good afternoon. Please give a warm welcome to Dr. Mark Johnson, U.S. Department of Energy.

  17. 7Li MRI of Li batteries reveals location of microstructural lithium...

    Office of Scientific and Technical Information (OSTI)

    Title: 7Li MRI of Li batteries reveals location of microstructural lithium Authors: Chandrashekar, S. ; Trease, Nicole M. ; Chang, Hee Jung ; Du, Lin-Shu ; Grey, Clare P. ; ...

  18. Fermi National Accelerator Laboratory November 2013

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

    is an international collaboration between U.S. universities, Fermilab in Illinois, Brookhaven National Laboratory in New York, and nine international labs and universities. It is...

  19. Fermi National Accelerator Laboratory September 2012

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

    years, is an expected byproduct of accelerator operations at Fermilab. As part of our environmental monitoring program, we regularly sample the water discharged into the creeks...

  20. Fermi National Accelerator Laboratory February 2015 Particle...

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

    known as synchrotron light sources to create the brightest light beams on Earth. These luminous sources provide tools for such applications as protein structure analysis,...

  1. GLAST (FERMI) Data-Processing Pipeline

    SciTech Connect (OSTI)

    Flath, Daniel L.; Johnson, Tony S.; Turri, Massimiliano; Heidenreich, Karen A.; /SLAC

    2011-08-12

    The Data Processing Pipeline ('Pipeline') has been developed for the Gamma-Ray Large Area Space Telescope (GLAST) which launched June 11, 2008. It generically processes graphs of dependent tasks, maintaining a full record of its state, history and data products. The Pipeline is used to automatically process the data down-linked from the satellite and to deliver science products to the GLAST collaboration and the Science Support Center and has been in continuous use since launch with great success. The pipeline handles up to 2000 concurrent jobs and in reconstructing science data produces approximately 750GB of data products using 1/2 CPU-year of processing time per day.

  2. Crystalline Phase of Strongly Interacting Fermi Mixtures

    SciTech Connect (OSTI)

    Petrov, D. S.; Astrakharchik, G. E.; Papoular, D. J.; Salomon, C.; Shlyapnikov, G. V.

    2007-09-28

    We show that the system of weakly bound molecules of heavy and light fermionic atoms is characterized by a long-range intermolecular repulsion and can undergo a gas-crystal quantum transition if the mass ratio exceeds a critical value. For the critical mass ratio above 100 obtained in our calculations, this crystalline order can be observed as a superlattice in an optical lattice for heavy atoms with a small filling factor. We also find that this novel system is sufficiently stable with respect to molecular relaxation into deep bound states and to the process of trimer formation.

  3. Fermi National Accelerator Laboratory February 2015

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

    to introduce youth to the world of science and trains college and university students in high-tech research and development. K-12 students FY2013 FY2014 K-12 teachers FY2013...

  4. Fermi National Accelerator Laboratory February 2013

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

    to introduce youth to the world of science and trains college and university students in high-tech research and development. K-12 students FY2011 FY2012 K-12 teachers FY2011...

  5. Fermi National Accelerator Laboratory April 2012

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

    technology. * With a strong focus on innovation and industrialization, IARC will attract high-tech companies and train Illinois citizens to develop advanced technology with...

  6. Fermi National Accelerator Laboratory March 2015

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

    630-840-5588 to register. Arts and Science Fermilab regularly hosts public events in Ramsey Auditorium, including lectures and arts performances. For a schedule, visit...

  7. 2015_OCTOBER.FermiOrgChart

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

    Particle Astrophysics Craig Hogan CMS Center Kevin Burkett Office of the General Counsel John Myer Office of Integrated Planning & Performance Management Erik Gottschalk Workforce...

  8. Fermi National Accelerator Laboratory August 2015

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

    one-eighth of the southern sky, recording information on 300 million galaxies, 100,000 galaxy clusters and 4,000 supernovae. The Dark Energy Survey is a collaborative effort...

  9. Fermi National Accelerator Laboratory August 2015

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

    5 In 2012 at the Large Hadron Collider, scientists discovered the long-sought Higgs boson. Now the question is: Are there more types of Higgs bosons? What is a Higgs boson? What is...

  10. Fermi National Accelerator Laboratory June 2012

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

    recorded two distinct top-quark production mechanisms Explored a new mass range for the Higgs boson and constrained its mass through top-quark and W-boson mass measurements...

  11. Graphic Standards Fermi National Accelerator Laboratory 2014

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

    onto your slide, click outside of the text areas on the slide, select Insert > Choose. Search for your file and click Insert. Drag the image to position it to fit on your slide...

  12. Fermi National Accelerator Laboratory April 2015

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

    thus explore whether the universe is even more complex than we think. Probing hints at new physics ICARUS: high-tech from Italy MicroBooNE: testing an anomaly SBND: closest to...

  13. Fermi National Accelerator Laboratory January 2015

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

    Drexel University Pennsylvania State University University of Pennsylvania, Philadelphia University of Pittsburgh Puerto Rico University of Puerto Rico, Mayaguez Rhode...

  14. Fermi National Accelerator Laboratory August 2013

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

    Drexel University Pennsylvania State University University of Pennsylvania, Philadelphia University of Pittsburgh, Pittsburgh Puerto Rico University of Puerto Rico,...

  15. Fermi National Accelerator Laboratory FY 2008

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

    University Carnegie Mellon University, Pittsburgh University of Pennsylvania, Philadelphia University of Pittsburgh, Pittsburgh Puerto Rico University of Puerto Rico,...

  16. Fermi National Accelerator Laboratory FY 2010

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

    Bucknell University Carnegie Mellon University, Pittsburgh Temple University, Philadelphia University of Pennsylvania, Philadelphia University of Pittsburgh, Pittsburgh...

  17. Correlation between Fermi surface transformations and superconductivit...

    Office of Scientific and Technical Information (OSTI)

    and superconductivity in the electron-doped high- T c superconductor Nd 2 - x Ce x CuO ... and superconductivity in the electron-doped high- T c superconductor Nd 2 - x Ce x CuO ...

  18. Fermi National Accelerator Laboratory Technologies Available...

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

    About Search Categories (15) Advanced Materials Biomass and Biofuels Building Energy Efficiency Electricity Transmission Energy Analysis Energy Storage Geothermal Hydrogen and...

  19. Fermi National Accelerator Laboratory June 2012

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

    intense beam of neutrinos, particles that may hold the key to understanding why the universe is made of matter. Using the cosmos as a laboratory, Fermilab scientists explore dark...

  20. Enrico Fermi: Audio/Video Clips

    Office of Scientific and Technical Information (OSTI)

    the nuclear chain reaction that took place on December 2, 1942, with context by narrator Jay Andre. (149K; 1 minute, 26 seconds) Alternative cannot be provided. Download QuickTime...

  1. Structure of DNA-Bound FEN1 Reveals Mechanism of Action

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

    Structure of DNA-Bound FEN1 Reveals Mechanism of Action Print DNA replication is a critical step in the life of all organisms, insuring that each new cell gets an accurate copy of...

  2. Structure of P-Glycoprotein Reveals a Molecular Basis for Poly...

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

    Structure of P-Glycoprotein Reveals a Molecular Basis for Poly-Specific Drug Binding figure 1 Figure 1. Structure of P-gp. Many forms of cancer fail to respond to chemotherapy by ...

  3. Structure of Human B[subscript 12] Trafficking Protein CblD Reveals...

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Search Results Journal Article: Structure of Human Bsubscript 12 Trafficking Protein CblD Reveals Molecular Mimicry and Identifies a New Subfamily of Nitro-FMN ...

  4. DOE Testing Reveals Samsung Refrigerator Does Not Meet Energy Star Requirements

    Broader source: Energy.gov [DOE]

    DOE-initiated testing has revealed that a Samsung refrigerator (model RF26VAB), which the company had claimed was Energy Star compliant, consumed more energy than permitted by the Energy Star...

  5. Revealing the Atomic Site-Dependent g Factor within a Single...

    Office of Scientific and Technical Information (OSTI)

    the Atomic Site-Dependent g Factor within a Single Magnetic Molecule via the Extended Kondo Effect Title: Revealing the Atomic Site-Dependent g Factor within a Single Magnetic ...

  6. Structure of Fc[gamma]RI in complex with Fc reveals the importance...

    Office of Scientific and Technical Information (OSTI)

    complex with Fc reveals the importance of glycan recognition for high-affinity IgG binding Citation Details In-Document Search Title: Structure of FcgammaRI in complex with Fc ...

  7. Covalent inhibition revealed by the crystal structure of the caspase-8/p35

    Office of Scientific and Technical Information (OSTI)

    complex (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Covalent inhibition revealed by the crystal structure of the caspase-8/p35 complex Citation Details In-Document Search Title: Covalent inhibition revealed by the crystal structure of the caspase-8/p35 complex Authors: Xu, Guozhou ; Cirilli, Maurizio ; Huang, Yihua ; Rich, Rebecca L. ; Myszka, David G. ; Wu, Hao [1] ; Weill-Med) [2] ; Utah) [2] + Show Author Affiliations Giordano ( Publication Date:

  8. Crystal Structure of MC159 Reveals Molecular Mechanism of DISC Assembly and

    Office of Scientific and Technical Information (OSTI)

    FLIP Inhibition (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Crystal Structure of MC159 Reveals Molecular Mechanism of DISC Assembly and FLIP Inhibition Citation Details In-Document Search Title: Crystal Structure of MC159 Reveals Molecular Mechanism of DISC Assembly and FLIP Inhibition Authors: Yang, Jin Kuk ; Wang, Liwei ; Zheng, Lixin ; Wan, Fengyi ; Ahmed, Misonara ; Lenardo, Michael J. ; Wu, Hao [1] ; NIH) [2] + Show Author Affiliations Weill-Med (

  9. Science Alliance Reveals STEM Pathways to the Future | Department of Energy

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

    Science Alliance Reveals STEM Pathways to the Future Science Alliance Reveals STEM Pathways to the Future October 26, 2015 - 12:54pm Addthis Students try their hands at arranging items in glove boxes during the Sixth Annual Science Alliance at the DOE Portsmouth Site in Piketon, Ohio. The three-day event included several contests for hundreds of attendees while providing an immersive learning experience. Students try their hands at arranging items in glove boxes during the Sixth Annual Science

  10. Revealing the Atomic Site-Dependent g Factor within a Single Magnetic

    Office of Scientific and Technical Information (OSTI)

    Molecule via the Extended Kondo Effect (Journal Article) | DOE PAGES DOE PAGES Search Results Publisher's Accepted Manuscript: Revealing the Atomic Site-Dependent g Factor within a Single Magnetic Molecule via the Extended Kondo Effect Title: Revealing the Atomic Site-Dependent g Factor within a Single Magnetic Molecule via the Extended Kondo Effect Authors: Liu, Liwei ; Yang, Kai ; Jiang, Yuhang ; Song, Boqun ; Xiao, Wende ; Song, Shiru ; Du, Shixuan ; Ouyang, Min ; Hofer, Werner A. ;

  11. X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance

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

    X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance Print Wednesday, 28 October 2015 00:00 Rechargeable lithium-ion batteries power most portable electronics and are becoming more widely used in large-scale applications like electric vehicles. Scientists have long observed that lithium iron phosphate nanoparticles are one of the best performing battery electrode materials, able to repeatedly charge and

  12. Revealing a steroid receptor ligand as a unique PPAR[gamma] agonist

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect Revealing a steroid receptor ligand as a unique PPAR[gamma] agonist Citation Details In-Document Search Title: Revealing a steroid receptor ligand as a unique PPAR[gamma] agonist Peroxisome proliferator-activated receptor gamma (PPAR{gamma}) regulates metabolic homeostasis and is a molecular target for anti-diabetic drugs. We report here the identification of a steroid receptor ligand, RU-486, as an unexpected PPAR{gamma} agonist, thereby uncovering a

  13. Revealing the Atomic Site-Dependent g Factor within a Single Magnetic

    Office of Scientific and Technical Information (OSTI)

    Molecule via the Extended Kondo Effect (Journal Article) | SciTech Connect Revealing the Atomic Site-Dependent g Factor within a Single Magnetic Molecule via the Extended Kondo Effect Citation Details In-Document Search Title: Revealing the Atomic Site-Dependent g Factor within a Single Magnetic Molecule via the Extended Kondo Effect Authors: Liu, Liwei ; Yang, Kai ; Jiang, Yuhang ; Song, Boqun ; Xiao, Wende ; Song, Shiru ; Du, Shixuan ; Ouyang, Min ; Hofer, Werner A. ; Castro Neto, Antonio

  14. Analyses of Candida Cdc13 Orthologues Revealed a Novel OB Fold Dimer

    Office of Scientific and Technical Information (OSTI)

    Arrangement, Dimerization-Assisted DNA Binding, and Substantial Structural Differences between Cdc13 and RPA70 (Journal Article) | SciTech Connect Analyses of Candida Cdc13 Orthologues Revealed a Novel OB Fold Dimer Arrangement, Dimerization-Assisted DNA Binding, and Substantial Structural Differences between Cdc13 and RPA70 Citation Details In-Document Search Title: Analyses of Candida Cdc13 Orthologues Revealed a Novel OB Fold Dimer Arrangement, Dimerization-Assisted DNA Binding, and

  15. Evolution of novel wood decay mechanisms in Agaricales revealed by the

    Office of Scientific and Technical Information (OSTI)

    genome sequences of Fistulina hepatica and Cylindrobasidium torrendii (Journal Article) | DOE PAGES Evolution of novel wood decay mechanisms in Agaricales revealed by the genome sequences of Fistulina hepatica and Cylindrobasidium torrendii « Prev Next » Title: Evolution of novel wood decay mechanisms in Agaricales revealed by the genome sequences of Fistulina hepatica and Cylindrobasidium torrendii Authors: Floudas, Dimitrios ; Held, Benjamin W. ; Riley, Robert ; Nagy, Laszlo G. ;

  16. Multi-omics analysis reveals regulators of the response to nitrogen

    Office of Scientific and Technical Information (OSTI)

    limitation in Yarrowia lipolytica (Journal Article) | DOE PAGES Multi-omics analysis reveals regulators of the response to nitrogen limitation in Yarrowia lipolytica « Prev Next » Title: Multi-omics analysis reveals regulators of the response to nitrogen limitation in Yarrowia lipolytica Yarrowia lipolytica is an oleaginous ascomycete yeast that stores lipids in response to limitation of nitrogen. Furthermore, while the enzymatic pathways responsible for neutral lipid accumulation in Y.

  17. Multi-omics analysis reveals regulators of the response to nitrogen

    Office of Scientific and Technical Information (OSTI)

    limitation in Yarrowia lipolytica (Journal Article) | DOE PAGES Multi-omics analysis reveals regulators of the response to nitrogen limitation in Yarrowia lipolytica « Prev Next » Title: Multi-omics analysis reveals regulators of the response to nitrogen limitation in Yarrowia lipolytica × You are accessing a document from the Department of Energy's (DOE) Public Access Gateway for Energy & Science (PAGES). This site is a product of DOE's Office of Scientific and Technical Information

  18. Structural Studies of AAV2 Rep68 Reveal a Partially Structured Linker and

    Office of Scientific and Technical Information (OSTI)

    Compact Domain Conformation (Journal Article) | SciTech Connect Structural Studies of AAV2 Rep68 Reveal a Partially Structured Linker and Compact Domain Conformation Citation Details In-Document Search Title: Structural Studies of AAV2 Rep68 Reveal a Partially Structured Linker and Compact Domain Conformation Authors: Musayev, F ; Zarate-Perez, F ; Bardelli, M ; Bishop, C ; Saniev, E ; Linden, R ; Henckaerts, E ; Escalante, C Publication Date: 2015-09-29 OSTI Identifier: 1229395 Report

  19. Structures of P-glycoprotein reveal its conformational flexibility and an

    Office of Scientific and Technical Information (OSTI)

    epitope on the nucleotide-binding domain (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Structures of P-glycoprotein reveal its conformational flexibility and an epitope on the nucleotide-binding domain Citation Details In-Document Search Title: Structures of P-glycoprotein reveal its conformational flexibility and an epitope on the nucleotide-binding domain Authors: Ward, Andrew B. ; Szewczyk, Paul ; Grimard, Vinciane ; Lee, Chang-Wook ; Martinez, Lorena

  20. The Crystal Structure of Mouse Exo70 Reveals Unique Features of the

    Office of Scientific and Technical Information (OSTI)

    Mammalian Exocyst (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: The Crystal Structure of Mouse Exo70 Reveals Unique Features of the Mammalian Exocyst Citation Details In-Document Search Title: The Crystal Structure of Mouse Exo70 Reveals Unique Features of the Mammalian Exocyst Authors: Moore, Brian A. ; Robinson, Howard H. ; Xu, Zhaohui [1] ; Michigan-Med) [2] + Show Author Affiliations BNL ( Publication Date: 2015-08-24 OSTI Identifier: 1186909

  1. Analysis of Strand-Specific RNA-Seq Data Using Machine Learning Reveals the

    Office of Scientific and Technical Information (OSTI)

    Structures of Transcription Units in Clostridium thermocellum (Journal Article) | SciTech Connect Analysis of Strand-Specific RNA-Seq Data Using Machine Learning Reveals the Structures of Transcription Units in Clostridium thermocellum Citation Details In-Document Search Title: Analysis of Strand-Specific RNA-Seq Data Using Machine Learning Reveals the Structures of Transcription Units in Clostridium thermocellum The identification of transcription units (TUs) encoded in a bacterial genome

  2. Aspects of Electron-Phonon Self-Energy Revealed From Angle-Resolved

    Office of Scientific and Technical Information (OSTI)

    Photoemission Spectroscopy (Journal Article) | SciTech Connect Aspects of Electron-Phonon Self-Energy Revealed From Angle-Resolved Photoemission Spectroscopy Citation Details In-Document Search Title: Aspects of Electron-Phonon Self-Energy Revealed From Angle-Resolved Photoemission Spectroscopy No abstract prepared. Authors: Lee, W.S. ; /Stanford U., Appl. Phys. Dept. /SLAC, SSRL ; Johnston, S. ; Devereaux, T.P. ; /Waterloo U. ; Shen, Z.X. ; /Stanford U., Appl. Phys. Dept. /SLAC, SSRL

  3. New Interactive Map Reveals U.S. Tidal Energy Resources | Department of

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

    Energy Interactive Map Reveals U.S. Tidal Energy Resources New Interactive Map Reveals U.S. Tidal Energy Resources July 7, 2011 - 10:50am Addthis A map generated by Georgia Tech's tidal energy resource database shows mean current speed of tidal streams | Source: Georgia Institute of Technology A map generated by Georgia Tech's tidal energy resource database shows mean current speed of tidal streams | Source: Georgia Institute of Technology Michael Reed Michael Reed Director, Technical and

  4. Jefferson Lab News - HAPPEx II reveals proton isn't very strange |

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

    Jefferson Lab HAPPEx II reveals proton isn't very strange HAPPEx II reveals proton isn't very strange April 23, 2006 The most precise measurement yet of strange quarks in the proton, performed at the Department of Energy's Thomas Jefferson National Accelerator Facility (Jefferson Lab) by the second phase of the Hall A Proton Parity Experiment (HAPPEx II), shows that the strange quark contribution to the proton's overall charge distribution and magnetic moment is small, indeed: it's so

  5. The crystal structure of choline kinase reveals a eukaryotic protein kinase

    Office of Scientific and Technical Information (OSTI)

    fold (Journal Article) | SciTech Connect The crystal structure of choline kinase reveals a eukaryotic protein kinase fold Citation Details In-Document Search Title: The crystal structure of choline kinase reveals a eukaryotic protein kinase fold Choline kinase catalyzes the ATP-dependent phosphorylation of choline, the first committed step in the CDP-choline pathway for the biosynthesis of phosphatidylcholine. The 2.0 {angstrom} crystal structure of a choline kinase from C. elegans (CKA-2)

  6. Environmental genomics reveals a single species ecosystem deep within the Earth

    SciTech Connect (OSTI)

    Chivian, Dylan; Brodie, Eoin L.; Alm, Eric J.; Culley, David E.; Dehal, Paramvir S.; DeSantis, Todd Z.; Gihring, Thomas M.; Lapidus, Alla; Lin, Li-Hung; Lowry, Stephen R.; Moser, Duane P.; Richardson, Paul; Southam, Gordon; Wanger, Greg; Pratt, Lisa M.; Andersen, Gary L.; Hazen, Terry C.; Brockman, Fred J.; Arkin, Adam P.; Onstott, Tullis C.

    2008-09-17

    DNA from low biodiversity fracture water collected at 2.8 km depth in a South African gold mine was sequenced and assembled into a single, complete genome. This bacterium, Candidatus Desulforudis audaxviator, comprises>99.9percent of the microorganisms inhabiting the fluid phase of this particular fracture. Its genome indicates a motile, sporulating, sulfate reducing, chemoautotrophic thermophile that can fix its own nitrogen and carbon using machinery shared with archaea. Candidatus Desulforudis audaxviator is capable of an independent lifestyle well suited to long-term isolation from the photosphere deep within Earth?s crust, and offers the first example of a natural ecosystem that appears to have its biological component entirely encoded within a single genome.

  7. Revealing the True Nature of a Metal Oxide | The Ames Laboratory

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

    Revealing the True Nature of a Metal Oxide Extensive calculations revealed that the calcium-iridium-oxygen compound CaIrO3 is a Slater-type insulator, putting to rest the debate of whether the insulating nature of the metal oxide is Mott-type or Slater-type. While both types are insulators, the insulating properties in Mott types arise from electron repulsion while in Slater types magnetic ordering plays a prominent role. Through a series of calculations, the team described the types of

  8. New Study Reveals Multiple Pathways to 30% Penetration of Wind and Solar |

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

    Department of Energy New Study Reveals Multiple Pathways to 30% Penetration of Wind and Solar New Study Reveals Multiple Pathways to 30% Penetration of Wind and Solar September 16, 2015 - 6:36pm Addthis A new study published by the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL) found that the U.S. Eastern Interconnection-one of the largest power systems in the world-can reliably support up to a 30% penetration of wind and solar power. Using high-performance

  9. Structure of DNA-Bound FEN1 Reveals Mechanism of Action

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

    Structure of DNA-Bound FEN1 Reveals Mechanism of Action Structure of DNA-Bound FEN1 Reveals Mechanism of Action Print Tuesday, 24 January 2012 11:30 DNA replication is a critical step in the life of all organisms, insuring that each new cell gets an accurate copy of the genome. Among the legions of proteins required to do this work, the DNA-slicing "flap endonuclease" FEN1 plays a key role. Much of FEN1's structure was solved previously, but the DNA-free structure failed to expose

  10. Full-length Gαq-phospholipase C-β3 structure reveals interfaces of the

    Office of Scientific and Technical Information (OSTI)

    C-terminal coiled-coil domain (Journal Article) | SciTech Connect Full-length Gαq-phospholipase C-β3 structure reveals interfaces of the C-terminal coiled-coil domain Citation Details In-Document Search Title: Full-length Gαq-phospholipase C-β3 structure reveals interfaces of the C-terminal coiled-coil domain Phospholipase C-β (PLCβ) is directly activated by Gαq, but the molecular basis for how its distal C-terminal domain (CTD) contributes to maximal activity is poorly understood.

  11. Interfacial effects revealed by ultrafast relaxation dynamics in BiFeO 3 /

    Office of Scientific and Technical Information (OSTI)

    YBa 2 Cu 3 O 7 bilayers (Journal Article) | SciTech Connect Interfacial effects revealed by ultrafast relaxation dynamics in BiFeO 3 / YBa 2 Cu 3 O 7 bilayers Citation Details In-Document Search This content will become publicly available on February 11, 2017 Title: Interfacial effects revealed by ultrafast relaxation dynamics in BiFeO 3 / YBa 2 Cu 3 O 7 bilayers Authors: Springer, D. ; Nair, Saritha K. ; He, Mi ; Lu, C. L. ; Cheong, S. A. ; Wu, T. ; Panagopoulos, C. ; Chia, Elbert E. M. ;

  12. Structure of Fc[gamma]RI in complex with Fc reveals the importance of

    Office of Scientific and Technical Information (OSTI)

    glycan recognition for high-affinity IgG binding (Journal Article) | SciTech Connect Structure of Fc[gamma]RI in complex with Fc reveals the importance of glycan recognition for high-affinity IgG binding Citation Details In-Document Search Title: Structure of Fc[gamma]RI in complex with Fc reveals the importance of glycan recognition for high-affinity IgG binding Authors: Lu, Jinghua ; Chu, Jonathan ; Zou, Zhongcheng ; Hamacher, Nels B. ; Rixon, Mark W. ; Sun, Peter D. [1] ; BMS) [2] + Show

  13. Structure of a Bud6/Actin Complex Reveals a Novel WH2-like Actin Monomer

    Office of Scientific and Technical Information (OSTI)

    Recruitment Motif (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Structure of a Bud6/Actin Complex Reveals a Novel WH2-like Actin Monomer Recruitment Motif Citation Details In-Document Search Title: Structure of a Bud6/Actin Complex Reveals a Novel WH2-like Actin Monomer Recruitment Motif Authors: Park, Eunyoung ; Graziano, Brian R. ; Zheng, Wei ; Garabedian, Mikael ; Goode, Bruce L. ; Eck, Michael J. [1] ; Harvard-Med) [2] ; Brandeis) [2] + Show Author

  14. SunShot Grand Challenge Highlights Ambitious Efforts along the Entire Solar Spectrum

    Broader source: Energy.gov [DOE]

    Today at the SunShot Grand Challenge Summit in Denver, Energy Secretary Steven Chu lauded progress in driving down the cost of solar.

  15. File:Wind-for-schools entire curriculum.pdf | Open Energy Information

    Open Energy Info (EERE)

    27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85...

  16. File:Wind-for-schools entire curriculum-HS.pdf | Open Energy...

    Open Energy Info (EERE)

    metadata was last modified 08:58, 7 August 2013 Software used Acrobat PDFMaker 9.0 for Word Conversion program Adobe PDF Library 9.0 Encrypted no Page size 612 x 792 pts (letter)...

  17. Using CEBAF,Physicists Find New Way to Reveal Neutron's Secrets (News @ Old

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

    Dominion University) | Jefferson Lab Using CEBAF,Physicists Find New Way to Reveal Neutron's Secrets (News @ Old Dominion University) External Link: http://ww2.odu.edu/ao/news/index.php?todo=details&id=32011 By jlab_admin on Thu, 2012-04-26

  18. Research Led by Sandia Reveals Leading-Edge Erosion Significantly Reduces Wind Turbine Performance

    Broader source: Energy.gov [DOE]

    Research conducted by DOE's Sandia National Laboratories revealed that leading-edge erosion on wind turbine blades can have a detrimental effect on wind turbine aerodynamic performance within the second year of operation. Light erosion may lead to a 5% decrease in annual energy production, and heavy erosion may reduce energy production by as much as 25%.

  19. Synaptic Arrangement of the Neuroligin/beta-Neurexin Complex Revealed by

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

    X-ray and Neutron Scattering Synaptic Arrangement of the Neuroligin/beta-Neurexin Complex Revealed by X-ray and Neutron Scattering Autism spectrum disorders are among the most devastating disorders of early childhood in terms of prevalence, family impact, and cost to society. Several mutations of the coding regions of the neuroligins and neurexins have been implicated through genetic screens in the pathogenesis of autism and mental retardation (Jamain et al., 2003; Laumonnier et al., 2004;

  20. Revealing a New Conformational State in a Chloride/Proton Exchanger |

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

    Stanford Synchrotron Radiation Lightsource Revealing a New Conformational State in a Chloride/Proton Exchanger Friday, January 29, 2016 "CLC" transporters are secondary active-transport membrane proteins that catalyze the transmembrane exchange of chloride (Cl-) for protons (H+). This exchange plays an essential role in proper cardiovascular, neuronal, muscular and epithelial functions. Several diseases arise from CLC defects, and several CLCs are therapeutic targets. For example,

  1. X-ray Study Reveals How Silver-to-Silicon Contacts Form for Solar Cells |

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

    Stanford Synchrotron Radiation Lightsource X-ray Study Reveals How Silver-to-Silicon Contacts Form for Solar Cells Saturday, April 30, 2016 Solar energy must be one of the primary energy sources as society transitions away from predominantly fossil fuels based economy. Currently, the overwhelming majority (>90%) of the photovoltaic (PV) market consists of silicon solar cells. While relatively inexpensive, this technology depends predominately on a screen-printed silver electrical

  2. X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance

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

    X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance Print Rechargeable lithium-ion batteries power most portable electronics and are becoming more widely used in large-scale applications like electric vehicles. Scientists have long observed that lithium iron phosphate nanoparticles are one of the best performing battery electrode materials, able to repeatedly charge and discharge in an extremely reversible manner, but the precise mechanism responsible for their performance

  3. X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance

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

    Microscopy Reveals How Crystal Mechanics Drive Battery Performance Print Rechargeable lithium-ion batteries power most portable electronics and are becoming more widely used in large-scale applications like electric vehicles. Scientists have long observed that lithium iron phosphate nanoparticles are one of the best performing battery electrode materials, able to repeatedly charge and discharge in an extremely reversible manner, but the precise mechanism responsible for their performance has

  4. Time-Resolved Small-Angle X-ray Scattering Studies Revealed Three Kinetic

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

    Stages of a T=4 Virus Maturation June 2010 Time-Resolved Small-Angle X-ray Scattering Studies Revealed Three Kinetic Stages of a T=4 Virus Maturation Most eukaryotic viruses, including HIV, influenza and herpes viruses, undergo maturation when transitioning from the noninfectious provirion to the infectious virion. Maturation processes involve reorganization of viral quaternary structure to defend viral gene from the cellular defense mechanism and lead to effective transfection. Nudaurelia

  5. X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance

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

    X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance Print Rechargeable lithium-ion batteries power most portable electronics and are becoming more widely used in large-scale applications like electric vehicles. Scientists have long observed that lithium iron phosphate nanoparticles are one of the best performing battery electrode materials, able to repeatedly charge and discharge in an extremely reversible manner, but the precise mechanism responsible for their performance

  6. X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance

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

    X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance Print Rechargeable lithium-ion batteries power most portable electronics and are becoming more widely used in large-scale applications like electric vehicles. Scientists have long observed that lithium iron phosphate nanoparticles are one of the best performing battery electrode materials, able to repeatedly charge and discharge in an extremely reversible manner, but the precise mechanism responsible for their performance

  7. X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance

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

    X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance Print Rechargeable lithium-ion batteries power most portable electronics and are becoming more widely used in large-scale applications like electric vehicles. Scientists have long observed that lithium iron phosphate nanoparticles are one of the best performing battery electrode materials, able to repeatedly charge and discharge in an extremely reversible manner, but the precise mechanism responsible for their performance

  8. X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance

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

    X-Ray Microscopy Reveals How Crystal Mechanics Drive Battery Performance Print Rechargeable lithium-ion batteries power most portable electronics and are becoming more widely used in large-scale applications like electric vehicles. Scientists have long observed that lithium iron phosphate nanoparticles are one of the best performing battery electrode materials, able to repeatedly charge and discharge in an extremely reversible manner, but the precise mechanism responsible for their performance

  9. New analyses reveal higher Four Corners methane emissions than suggested by

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

    EPA Higher methane emissions at Four Corners Community Connections: Your link to news and opportunities from Los Alamos National Laboratory Latest Issue:May 2016 all issues All Issues » submit New analyses reveal higher Four Corners methane emissions than suggested by EPA Looking at fossil mining industry as a whole is key December 1, 2014 Los Alamos National Laboratory equipment measuring Four Corners area power plant emissions. The station is located near the community of Waterflow at the

  10. Fermi arcs vs. fermi pockets in electron-doped perovskite iridates...

    Office of Scientific and Technical Information (OSTI)

    (China) Boston College, Chestnut Hill, MA (United States); Univ. of California, Santa Barbara, CA (United States) Publication Date: 2015-02-23 OSTI Identifier: 1188332 ...

  11. Cryogenic EBSD reveals structure of directionally solidified icepolymer composite

    SciTech Connect (OSTI)

    Donius, Amalie E.; Obbard, Rachel W.; Burger, Joan N.; Hunger, Philipp M.; Baker, Ian; Doherty, Roger D.; Wegst, Ulrike G.K.

    2014-07-01

    Despite considerable research efforts on directionally solidified or freeze-cast materials in recent years, little fundamental knowledge has been gained that links model with experiment. In this contribution, the cryogenic characterization of directionally solidified polymer solutions illustrates, how powerful cryo-scanning electron microscopy combined with electron backscatter diffraction is for the structural characterization of icepolymer composite materials. Under controlled sublimation, the freeze-cast polymer scaffold structure is revealed and imaged with secondary electrons. Electron backscatter diffraction fabric analysis shows that the ice crystals, which template the polymer scaffold and create the lamellar structure, have a-axes oriented parallel to the direction of solidification and the c-axes perpendicular to it. These results indicate the great potential of both cryo-scanning electron microscopy and cryo-electron backscatter diffraction in gaining fundamental knowledge of structurepropertyprocessing correlations. - Highlights: Cryo-SEM of freeze-cast polymer solution reveals an ice-templated structure. Cryo-EBSD reveals the ice crystal a-axis to parallel the solidification direction. The honeycomb-like polymer phase favors columnar ridges only on one side. Combining cryo-SEM with EBSD links solidification theory with experiment.

  12. Slow dynamics of nanocomposite polymer aerogels as revealed by X-ray photocorrelation spectroscopy (XPCS)

    SciTech Connect (OSTI)

    Hernndez, Rebeca, E-mail: rhernandez@ictp.csic.es, E-mail: aurora.nogales@csic.es; Mijangos, Carmen [Instituto de Ciencia y Tecnologa de Polmeros, ICTP-CSIC, Juan de la Cierva, 3, 28006 Madrid (Spain)] [Instituto de Ciencia y Tecnologa de Polmeros, ICTP-CSIC, Juan de la Cierva, 3, 28006 Madrid (Spain); Nogales, Aurora, E-mail: rhernandez@ictp.csic.es, E-mail: aurora.nogales@csic.es; Ezquerra, Tiberio A. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain)] [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain); Sprung, Michael [Petra III at DESY, Notkestr. 85, 22607 Hamburg (Germany)] [Petra III at DESY, Notkestr. 85, 22607 Hamburg (Germany)

    2014-01-14

    We report on a novel slow dynamics of polymer xerogels, aerogels, and nanocomposite aerogels with iron oxide nanoparticles, as revealed by X-ray photon correlation spectroscopy. The polymer aerogel and its nanocomposite aerogels, which are porous in nature, exhibit hyper-diffusive dynamics at room temperature. In contrast, non-porous polymer xerogels exhibit an absence of this peculiar dynamics. This slow dynamical process has been assigned to a relaxation of the characteristic porous structure of these materials and not to the presence of nanoparticles.

  13. Assembly and Evolution of Complex Fe-S Clusters as Revealed by X-ray

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

    Crystallography Assembly and Evolution of Complex Fe-S Clusters as Revealed by X-ray Crystallography Complex Fe-S cluster-containing enzymes are ubiquitous in nature where they are involved in a number of fundamental reactions for life including carbon dioxide fixation, nitrogen fixation, and hydrogen metabolism. One of the more complex and unusual biological clusters is found in the [FeFe]-hydrogenase. The active-site H-cluster in these enzymes has a [4Fe-4S] subcluster bridged via a

  14. Structure of DNA-Bound FEN1 Reveals Mechanism of Action

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

    Structure of DNA-Bound FEN1 Reveals Mechanism of Action Print DNA replication is a critical step in the life of all organisms, insuring that each new cell gets an accurate copy of the genome. Among the legions of proteins required to do this work, the DNA-slicing "flap endonuclease" FEN1 plays a key role. Much of FEN1's structure was solved previously, but the DNA-free structure failed to expose information about the mechanics of how it works. An international team of scientists led by

  15. Structure of DNA-Bound FEN1 Reveals Mechanism of Action

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

    Structure of DNA-Bound FEN1 Reveals Mechanism of Action Print DNA replication is a critical step in the life of all organisms, insuring that each new cell gets an accurate copy of the genome. Among the legions of proteins required to do this work, the DNA-slicing "flap endonuclease" FEN1 plays a key role. Much of FEN1's structure was solved previously, but the DNA-free structure failed to expose information about the mechanics of how it works. An international team of scientists led by

  16. Latitudinal survey of middle atmospheric water vapor revealed by shipboard microwave spectroscopy. Master's thesis

    SciTech Connect (OSTI)

    Schrader, M.L.

    1994-05-01

    Water vapor is one of the most important greenhouse gases and is an important tracer of atmospheric motions in the middle atmosphere. It also plays an important role in the chemistry of the middle atmosphere and through its photodissociation by solar radiation, it is the major source of hydrogen escaping to space. Ground-based microwave measurements conducted in the 1980s have provided a fair understanding of the seasonal variation of mesospheric water vapor in the northern hemisphere mid-latitudes, but the global distribution of water vapor in the middle atmosphere is only beginning to be revealed by space-based measurements.

  17. A fast grain-growth mechanism revealed in nanocrystalline ceramic-oxides

    SciTech Connect (OSTI)

    Aidhy, Dilpuneet S; Zhang, Yanwen; Weber, William J

    2014-01-01

    Grain growth problem in nanocrystalline ceramic-oxides renders their highly attractive properties practically unusable due to limited understanding on the underlying grain growth mechanisms. Two conventional 'slow' grain-growth mechanisms, i.e., curvature-driven and grainrotation driven, are shown to be thermally active, and the discovery of a 'fast' disorder-driven mechanism is revealed using molecular dynamics simulation on nanocrystalline ceria, in conjunction with experimental observations. We elucidate that this disorder mechanism drives the unexpected fast grain growth observed experimentally during synthesis and irradiation conditions.

  18. Biomimetic Model Studies Reveal the Role of the Ca2+ Ion in Photosystem II

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

    | Stanford Synchrotron Radiation Lightsource Biomimetic Model Studies Reveal the Role of the Ca2+ Ion in Photosystem II Friday, October 31, 2014 Fig 1 Figure 1. The biomimetic complexes that model the OEC in the final step of water oxidation. In these complexes, a redox-active iron atom (orange) is bound to a TMC ligand (1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, shown in gray and blue) and a peroxide moiety (red), which binds a redox- inactive metal ion (Mn+, green). Mn+ =

  19. Structure of DNA-Bound FEN1 Reveals Mechanism of Action

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

    Structure of DNA-Bound FEN1 Reveals Mechanism of Action Print DNA replication is a critical step in the life of all organisms, insuring that each new cell gets an accurate copy of the genome. Among the legions of proteins required to do this work, the DNA-slicing "flap endonuclease" FEN1 plays a key role. Much of FEN1's structure was solved previously, but the DNA-free structure failed to expose information about the mechanics of how it works. An international team of scientists led by

  20. Structure of DNA-Bound FEN1 Reveals Mechanism of Action

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

    Structure of DNA-Bound FEN1 Reveals Mechanism of Action Print DNA replication is a critical step in the life of all organisms, insuring that each new cell gets an accurate copy of the genome. Among the legions of proteins required to do this work, the DNA-slicing "flap endonuclease" FEN1 plays a key role. Much of FEN1's structure was solved previously, but the DNA-free structure failed to expose information about the mechanics of how it works. An international team of scientists led by

  1. The elastase-PK101 structure: Mechanism of an ultrasensitive activity-based probe revealed

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

    Lechtenberg, Bernhard C.; Robinson, Howard R.; Kasperkiewicz, Paulina; Drag, Marcin; Riedl, Stefan J.

    2015-01-22

    Human neutrophil elastase (HNE) plays a central role in neutrophil host defense, but its broad specificity makes HNE a difficult target for both inhibitor and probe development. Recently, we identified the unnatural amino acid containing activity-based probe PK101, which exhibits astounding sensitivity and selectivity for HNE, yet completely lacks mechanistic explanation for its unique characteristics. Here, we present the crystal structure of the HNE-PK101 complex which not only reveals the basis for PK101 ultrasensitivity but also uncovers so far unrecognized HNE features. Strikingly, the Nle(O-Bzl) function in the P4 position of PK101 reveals and leverages an “exo-pocket” on HNE asmore » a critical factor for selectivity. Furthermore, the PK101 P3 position harbors a methionine dioxide function, which mimics a post-translationally oxidized methionine residue and forms a critical hydrogen bond to the backbone amide of Gly219 of HNE. Gly219 resides in a Gly–Gly motif that is unique to HNE, yet compulsory for this interaction. Consequently, this feature enables HNE to accommodate substrates that have undergone methionine oxidation, which constitutes a hallmark post-translational modification of neutrophil signaling.« less

  2. Comparative genomic analysis reveals a distant liver enhancer upstream of the COUP-TFII gene

    SciTech Connect (OSTI)

    Baroukh, Nadine; Ahituv, Nadav; Chang, Jessie; Shoukry, Malak; Afzal, Veena; Rubin, Edward M.; Pennacchio, Len A.

    2004-08-20

    COUP-TFII is a central nuclear hormone receptor that tightly regulates the expression of numerous target lipid metabolism genes in vertebrates. However, it remains unclear how COUP-TFII itself is transcriptionally controlled since studies with its promoter and upstream region fail to recapitulate the genes liver expression. In an attempt to identify liver enhancers in the vicinity of COUP-TFII, we employed a comparative genomic approach. Initial comparisons between humans and mice of the 3,470kb gene poor region surrounding COUP-TFII revealed 2,023 conserved non-coding elements. To prioritize a subset of these elements for functional studies, we performed further genomic comparisons with the orthologous pufferfish (Fugu rubripes) locus and uncovered two anciently conserved non-coding sequences (CNS) upstream of COUP-TFII (CNS-62kb and CNS-66kb). Testing these two elements using reporter constructs in liver (HepG2) cells revealed that CNS-66kb, but not CNS-62kb, yielded robust in vitro enhancer activity. In addition, an in vivo reporter assay using naked DNA transfer with CNS-66kb linked to luciferase displayed strong reproducible liver expression in adult mice, further supporting its role as a liver enhancer. Together, these studies further support the utility of comparative genomics to uncover gene regulatory sequences based on evolutionary conservation and provide the substrates to better understand the regulation and expression of COUP-TFII.

  3. Revealing the Preferred Interlayer Orientations and Stackings of Two-Dimensional Bilayer Gallium Selenide Crystals

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

    Li, Xufan; Yoon, Mina; Puretzky, Alexander A; Lee, Jaekwang; Idrobo Tapia, Juan Carlos; Chi, Miaofang; Rouleau, Christopher M; Geohegan, David B; Xiao, Kai

    2015-01-01

    Characterizing and controlling the interlayer orientations and stacking order of bilayer two-dimensional (2D) crystals and van der Waals (vdW) heterostructure is crucial to optimize their electrical and optoelectronic properties. The four polymorphs of layered gallium selenide (GaSe) that result from different layer stacking provide an ideal platform to study the stacking configurations in bilayer 2D crystals. Here, through a controllable vapor-phase deposition method we selectively grow bilayer GaSe crystals and investigate their two preferred 0 or 60 interlayer rotations. The commensurate stacking configurations (AA and AB-stacking) in as-grown 2D bilayer GaSe crystals are clearly observed at the atomic scale andmore » the Ga-terminated edge structure are identified for the first time by using atomic-resolution scanning transmission electron microscopy (STEM). Theoretical analysis of the interlayer coupling energetics vs. interlayer rotation angle reveals that the experimentally-observed orientations are energetically preferred among the bilayer GaSe crystal polytypes. The combined experimental and theoretical characterization of the GaSe bilayers afforded by these growth studies provide a pathway to reveal the atomistic relationships in interlayer orientations responsible for the electronic and optical properties of bilayer 2D crystals and vdW heterostructures.« less

  4. Structures of Cryptococcus neoformans Protein Farnesyltransferase Reveal Strategies for Developing Inhibitors That Target Fungal Pathogens

    SciTech Connect (OSTI)

    Hast, Michael A.; Nichols, Connie B.; Armstrong, Stephanie M.; Kelly, Shannon M.; Hellinga, Homme W.; Alspaugh, J. Andrew; Beese, Lorena S.

    2012-09-17

    Cryptococcus neoformans is a fungal pathogen that causes life-threatening infections in immunocompromised individuals, including AIDS patients and transplant recipients. Few antifungals can treat C. neoformans infections, and drug resistance is increasing. Protein farnesyltransferase (FTase) catalyzes post-translational lipidation of key signal transduction proteins and is essential in C. neoformans. We present a multidisciplinary study validating C. neoformans FTase (CnFTase) as a drug target, showing that several anticancer FTase inhibitors with disparate scaffolds can inhibit C. neoformans and suggesting structure-based strategies for further optimization of these leads. Structural studies are an essential element for species-specific inhibitor development strategies by revealing similarities and differences between pathogen and host orthologs that can be exploited. We, therefore, present eight crystal structures of CnFTase that define the enzymatic reaction cycle, basis of ligand selection, and structurally divergent regions of the active site. Crystal structures of clinically important anticancer FTase inhibitors in complex with CnFTase reveal opportunities for optimization of selectivity for the fungal enzyme by modifying functional groups that interact with structurally diverse regions. A substrate-induced conformational change in CnFTase is observed as part of the reaction cycle, a feature that is mechanistically distinct from human FTase. Our combined structural and functional studies provide a framework for developing FTase inhibitors to treat invasive fungal infections.

  5. Structural Analysis of a Ternary Complex of Allantoate Amidohydrolase from Escherichia Coli Reveals its Mechanics

    SciTech Connect (OSTI)

    Agarwal,R.; Burley, S.; Swaminathan, S.

    2007-01-01

    Purine metabolism plays a major role in regulating the availability of purine nucleotides destined for nucleic acid synthesis. Allantoate amidohydrolase catalyzes the conversion of allantoate to (S)-ureidoglycolate, one of the crucial alternate steps in purine metabolism. The crystal structure of a ternary complex of allantoate amidohydrolase with its substrate allantoate and an allosteric effector, a sulfate ion, from Escherichia coli was determined to understand better the catalytic mechanism and substrate specificity. The 2.25 {angstrom} resolution X-ray structure reveals an {alpha}/{beta} scaffold akin to zinc exopeptidases of the peptidase M20 family and lacks the ({beta}/{alpha}){sub 8}-barrel fold characteristic of the amidohydrolases. Arrangement of the substrate and the two co-catalytic zinc ions at the active site governs catalytic specificity for hydrolysis of N-carbamyl versus the peptide bond in exopeptidases. In its crystalline form, allantoate amidohydrolase adopts a relatively open conformation. However, structural analysis reveals the possibility of a significant movement of domains via rotation about two hinge regions upon allosteric effector and substrate binding resulting in a closed catalytically competent conformation by bringing the substrate allantoate closer to co-catalytic zinc ions. Two cis-prolyl peptide bonds found on either side of the dimerization domain in close proximity to the substrate and ligand-binding sites may be involved in protein folding and in preserving the integrity of the catalytic site.

  6. NFkappaB Selectivity of Estrogen Receptor Ligands Revealed By Comparative Crystallographic Analyses

    SciTech Connect (OSTI)

    Nettles, K.W.; Bruning, J.B.; Gil, G.; Nowak, J.; Sharma, S.K.; Hahm, J.B.; Kulp, K.; Hochberg, R.B.; Zhou, H.; Katzenellenbogen, J.A.; Katzenllenbogen, B.S.; Kim, Y.; Joachmiak, A.; Greene, G.L.

    2009-05-22

    Our understanding of how steroid hormones regulate physiological functions has been significantly advanced by structural biology approaches. However, progress has been hampered by misfolding of the ligand binding domains in heterologous expression systems and by conformational flexibility that interferes with crystallization. Here, we show that protein folding problems that are common to steroid hormone receptors are circumvented by mutations that stabilize well-characterized conformations of the receptor. We use this approach to present the structure of an apo steroid receptor that reveals a ligand-accessible channel allowing soaking of preformed crystals. Furthermore, crystallization of different pharmacological classes of compounds allowed us to define the structural basis of NF{kappa}B-selective signaling through the estrogen receptor, thus revealing a unique conformation of the receptor that allows selective suppression of inflammatory gene expression. The ability to crystallize many receptor-ligand complexes with distinct pharmacophores allows one to define structural features of signaling specificity that would not be apparent in a single structure.

  7. Revealing the Preferred Interlayer Orientations and Stackings of Two-Dimensional Bilayer Gallium Selenide Crystals

    SciTech Connect (OSTI)

    Li, Xufan; Basile Carrasco, Leonardo A; Yoon, Mina; Ma, Cheng; Puretzky, Alexander A; Lee, Jaekwang; Idrobo Tapia, Juan Carlos; Chi, Miaofang; Rouleau, Christopher M; Geohegan, David B; Xiao, Kai

    2015-01-01

    Characterizing and controlling the interlayer orientations and stacking order of bilayer two-dimensional (2D) crystals and van der Waals (vdW) heterostructure is crucial to optimize their electrical and optoelectronic properties. The four polymorphs of layered gallium selenide (GaSe) that result from different layer stacking provide an ideal platform to study the stacking configurations in bilayer 2D crystals. Here, through a controllable vapor-phase deposition method we selectively grow bilayer GaSe crystals and investigate their two preferred 0 or 60 interlayer rotations. The commensurate stacking configurations (AA and AB-stacking) in as-grown 2D bilayer GaSe crystals are clearly observed at the atomic scale and the Ga-terminated edge structure are identified for the first time by using atomic-resolution scanning transmission electron microscopy (STEM). Theoretical analysis of the interlayer coupling energetics vs. interlayer rotation angle reveals that the experimentally-observed orientations are energetically preferred among the bilayer GaSe crystal polytypes. The combined experimental and theoretical characterization of the GaSe bilayers afforded by these growth studies provide a pathway to reveal the atomistic relationships in interlayer orientations responsible for the electronic and optical properties of bilayer 2D crystals and vdW heterostructures.

  8. Human-mouse comparative genomics: successes and failures to reveal functional regions of the human genome

    SciTech Connect (OSTI)

    Pennacchio, Len A.; Baroukh, Nadine; Rubin, Edward M.

    2003-05-15

    Deciphering the genetic code embedded within the human genome remains a significant challenge despite the human genome consortium's recent success at defining its linear sequence (Lander et al. 2001; Venter et al. 2001). While useful strategies exist to identify a large percentage of protein encoding regions, efforts to accurately define functional sequences in the remaining {approx}97 percent of the genome lag. Our primary interest has been to utilize the evolutionary relationship and the universal nature of genomic sequence information in vertebrates to reveal functional elements in the human genome. This has been achieved through the combined use of vertebrate comparative genomics to pinpoint highly conserved sequences as candidates for biological activity and transgenic mouse studies to address the functionality of defined human DNA fragments. Accordingly, we describe strategies and insights into functional sequences in the human genome through the use of comparative genomics coupled wit h functional studies in the mouse.

  9. Sub-structure of laser generated harmonics reveals plasma dynamics of a relativistically oscillating mirror

    SciTech Connect (OSTI)

    Braenzel, J.; Schnürer, M.; Steinke, S.; Priebe, G.; Sandner, W.; Andreev, A.; Vavilov State Optical Institute, Birzhevaya line 4, 199034 St. Petersburg ; Platonov, K.

    2013-08-15

    Theoretical and experimental investigations of the dynamics of a relativistically oscillating plasma slab reveal spectral line splitting in laser driven harmonic spectra, leading to double harmonic series. Both series are well characterized with harmonics arising by two fundamental frequencies. While a relativistic oscillation of the critical density drives the harmonic emission, the splitting is a result of an additional acceleration during the laser pulse duration. In comparison with the oscillatory movement, this acceleration is rather weak and can be described by a plasma shock wave driven by the pressure of light. We introduce particle in cell simulations and an analytical model explaining the harmonic line splitting. The derived analytical formula gives direct access between the splitting in the harmonic spectrum and the acceleration of the plasma surface.

  10. Crystal Structure of the HP1-EMSY Complex Reveals an Unusual Mode of HP1 Binding

    SciTech Connect (OSTI)

    Huang,Y.; Myers, M.; Xu, R.

    2006-01-01

    Heterochromatin protein-1 (HP1) plays an essential role in both the assembly of higher-order chromatin structure and epigenetic inheritance. The C-terminal chromo shadow domain (CSD) of HP1 is responsible for homodimerization and interaction with a number of chromatin-associated nonhistone proteins, including EMSY, which is a BRCA2-interacting protein that has been implicated in the development of breast and ovarian cancer. We have determined the crystal structure of the HP1{beta} CSD in complex with the N-terminal domain of EMSY at 1.8 Angstroms resolution. Surprisingly, the structure reveals that EMSY is bound by two HP1 CSD homodimers, and the binding sequences differ from the consensus HP1 binding motif PXVXL. This structural information expands our understanding of HP1 binding specificity and provides insights into interactions between HP1 homodimers that are likely to be important for heterochromatin formation.

  11. THREE-DIMENSIONAL DUST MAPPING REVEALS THAT ORION FORMS PART OF A LARGE RING OF DUST

    SciTech Connect (OSTI)

    Schlafly, E. F.; Rix, H.-W.; Martin, N. F.; Green, G.; Finkbeiner, D. P.; Burgett, W. S.; Chambers, K. C.; Kaiser, N.; Morgan, J. S.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.; Draper, P. W.; Metcalfe, N.; Price, P. A.

    2015-02-01

    The Orion Molecular Complex is the nearest site of ongoing high-mass star formation, making it one of the most extensively studied molecular complexes in the Galaxy. We have developed a new technique for mapping the three-dimensional distribution of dust in the Galaxy using Pan-STARRS1 photometry. We isolate the dust at the distance to Orion using this technique, revealing a large (100 pc, 14 diameter), previously unrecognized ring of dust, which we term the ''Orion dust ring''. The ring includes Orion A and B, and is not coincident with current H? features. The circular morphology suggests formation as an ancient bubble in the interstellar medium, though we have not been able to conclusively identify the source of the bubble. This hint at the history of Orion may have important consequences for models of high-mass star formation and triggered star formation.

  12. Revealing the Differences Between Free and Complexed Enzyme Mechanisms and Factors Contributing to Cell Wall Recalcitrance

    SciTech Connect (OSTI)

    Resch, M.

    2014-09-08

    Enzymatic depolymerization of polysaccharides is a key step in the production of fuels and chemicals from lignocellulosic biomass, and discovery of synergistic biomass-degrading enzyme paradigms will enable improved conversion processes. Historically, revealing insights into enzymatic saccharification mechanisms on plant cell walls has been hindered by uncharacterized substrates and low resolution imaging techniques. Also, translating findings between model substrates to intact biomass is critical for evaluating enzyme performance. Here we employ a fungal free enzyme cocktail, a complexed cellulosomal system, and a combination of the two to investigate saccharification mechanisms on cellulose I, II and III along with corn stover from Clean Fractionation (CF), which is an Organosolv pretreatment. The insoluble Cellulose Enriched Fraction (CEF) from CF contains mainly cellulose with minor amounts of residual hemicellulose and lignin, the amount of which depends on the CF pretreatment severity. Enzymatic digestions at both low and high-solids loadings demonstrate that CF reduces the amount of enzyme required to depolymerize polysaccharides relative to deacetylated, dilute acid pretreated corn stover. Transmission and scanning electron microscopy of the biomass provides evidence for the different mechanisms of enzymatic deconstruction between free and complexed enzyme systems, and reveals the basis for the synergistic relationship between the two enzyme paradigms on a process-relevant substrate for the first time. These results also demonstrate that the presence of lignin, rather than cellulose morphology, is more detrimental to cellulosome action than to free cellulases. As enzyme costs are a major economic driver for biorefineries, this study provides key inputs for the evaluation of CF as a pretreatment method for biomass conversion.

  13. Metagenomics, metatranscriptomics and single cell genomics reveal functional response of active Oceanospirillales to Gulf oil spill

    SciTech Connect (OSTI)

    Mason, Olivia U.; Hazen, Terry C.; Borglin, Sharon; Chain, Patrick S. G.; Dubinsky, Eric A.; Fortney, Julian L.; Han, James; Holman, Hoi-Ying N.; Hultman, Jenni; Lamendella, Regina; Mackelprang, Rachel; Malfatti, Stephanie; Tom, Lauren M.; Tringe, Susannah G.; Woyke, Tanja; Zhou, Jizhong; Rubin, Edward M.; Jansson, Janet K.

    2012-06-12

    The Deepwater Horizon oil spill in the Gulf of Mexico resulted in a deep-sea hydrocarbon plume that caused a shift in the indigenous microbial community composition with unknown ecological consequences. Early in the spill history, a bloom of uncultured, thus uncharacterized, members of the Oceanospirillales was previously detected, but their role in oil disposition was unknown. Here our aim was to determine the functional role of the Oceanospirillales and other active members of the indigenous microbial community using deep sequencing of community DNA and RNA, as well as single-cell genomics. Shotgun metagenomic and metatranscriptomic sequencing revealed that genes for motility, chemotaxis and aliphatic hydrocarbon degradation were significantly enriched and expressed in the hydrocarbon plume samples compared with uncontaminated seawater collected from plume depth. In contrast, although genes coding for degradation of more recalcitrant compounds, such as benzene, toluene, ethylbenzene, total xylenes and polycyclic aromatic hydrocarbons, were identified in the metagenomes, they were expressed at low levels, or not at all based on analysis of the metatranscriptomes. Isolation and sequencing of two Oceanospirillales single cells revealed that both cells possessed genes coding for n-alkane and cycloalkane degradation. Specifically, the near-complete pathway for cyclohexane oxidation in the Oceanospirillales single cells was elucidated and supported by both metagenome and metatranscriptome data. The draft genome also included genes for chemotaxis, motility and nutrient acquisition strategies that were also identified in the metagenomes and metatranscriptomes. These data point towards a rapid response of members of the Oceanospirillales to aliphatic hydrocarbons in the deep sea.

  14. Low-Temperature Biodiesel Research Reveals Potential Key to Successful Blend Performance (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2012-02-01

    Relatively low-cost solutions could improve reliability while making biodiesel blends an affordable option. While biodiesel has very low production costs and the potential to displace up to 10% of petroleum diesel, until now, issues with cold weather performance have prevented biodiesel blends from being widely adopted. Some biodiesel blends have exhibited unexplained low-temperature performance problems even at blend levels as low as 2% by volume. The most common low-temperature performance issue is vehicle stalling caused by fuel filter clogging, which prevents fuel from reaching the engine. Research at the National Renewable Energy Laboratory (NREL) reveals the properties responsible for these problems, clearing a path for the development of solutions and expanded use of energy-conserving and low-emissions alternative fuel. NREL researchers set out to study the unpredictable nature of biodiesel crystallization, the condition that impedes the flow of fuel in cold weather. Their research revealed for the first time that saturated monoglyceride impurities common to the biodiesel manufacturing process create crystals that can cause fuel filter clogging and other problems when cooling at slow rates. Biodiesel low-temperature operational problems are commonly referred to as 'precipitates above the cloud point (CP).' NREL's Advanced Biofuels team spiked distilled soy and animal fat-derived B100, as well as B20, B10, and B5 biodiesel blends with three saturated monoglycerides (SMGs) at concentration levels comparable to those of real-world fuels. Above a threshold or eutectic concentration, the SMGs (monomyristin, monopalmitin, and monostearin) were shown to significantly raise the biodiesel CP, and had an even greater impact on the final melting temperature. Researchers discovered that upon cooling, monoglyceride initially precipitates as a metastable crystal, but it transforms over time or upon slight heating into a more stable crystal with a much lower solubility and higher melting temperature - and with increased potential to cause vehicle performance issues. This explains why fuel-filter clogging typically occurs over the course of long, repeated diurnal cooling cycles. The elevated final melting points mean that restarting vehicles with clogged filters can be difficult even after ambient temperatures have warmed to well above CP. By examining how biodiesel impurities affect filtration and crystallization during warming and cooling cycles, NREL researchers uncovered an explanation for poor biodiesel performance at low temperatures. The observation of a eutectic point, or a concentration below which SMGs have no effect, indicates that SMGs do not have to be completely removed from biodiesel to solve low-temperature performance problems.

  15. Crystal structure of the Alcanivorax borkumensis YdaH transporter reveals an unusual topology

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

    Bolla, Jani Reddy; Su, Chih-Chia; Delmar, Jared A.; Radhakrishnan, Abhijith; Kumar, Nitin; Chou, Tsung-Han; Long, Feng; Rajashankar, Kanagalaghatta R.; Yu, Edward W.

    2015-04-20

    The potential of the folic acid biosynthesis pathway as a target for the development of antibiotics has been clinically validated. However, many pathogens have developed resistance to these antibiotics, prompting a re-evaluation of potential drug targets within the pathway. The ydaH gene of Alcanivorax borkumensis encodes an integral membrane protein of the AbgT family of transporters for which no structural information was available. Here we report the crystal structure of A. borkumensis YdaH, revealing a dimeric molecule with an architecture distinct from other families of transporters. YdaH is a bowl-shaped dimer with a solvent-filled basin extending from the cytoplasm tomore » halfway across the membrane bilayer. Each subunit of the transporter contains nine transmembrane helices and two hairpins that suggest a plausible pathway for substrate transport. Further analyses also suggest that YdaH could act as an antibiotic efflux pump and mediate bacterial resistance to sulfonamide antimetabolite drugs.« less

  16. A Korarchael Genome Reveals Insights into the Evolution of the Archaea

    SciTech Connect (OSTI)

    Lapidus, Alla; Elkins, James G.; Podar, Mircea; Graham, David E.; Makarova, Kira S.; Wolf, Yuri; Randau, Lennart; Hedlund, Brian P.; Brochier-Armanet, Celine; Kunin, Victor; Anderson, Iain; Lapidus, Alla; Goltsman, Eugene; Barry, Kerrie; Koonin, Eugene V.; Hugenholtz, Phil; Kyrpides, Nikos; Wanner, Gerhard; Richardson, Paul; Keller, Martin; Stetter, Karl O.

    2008-01-07

    The candidate division Korarchaeota comprises a group of uncultivated microorganisms that, by their small subunit rRNA phylogeny, may have diverged early from the major archaeal phyla Crenarchaeota and Euryarchaeota. Here, we report the initial characterization of a member of the Korarchaeota with the proposed name, ?Candidatus Korarchaeum cryptofilum,? which exhibits an ultrathin filamentous morphology. To investigate possible ancestral relationships between deep-branching Korarchaeota and other phyla, we used whole-genome shotgun sequencing to construct a complete composite korarchaeal genome from enriched cells. The genome was assembled into a single contig 1.59 Mb in length with a G + C content of 49percent. Of the 1,617 predicted protein-coding genes, 1,382 (85percent) could be assigned to a revised set of archaeal Clusters of Orthologous Groups (COGs). The predicted gene functions suggest that the organism relies on a simple mode of peptide fermentation for carbon and energy and lacks the ability to synthesize de novo purines, CoA, and several other cofactors. Phylogenetic analyses based on conserved single genes and concatenated protein sequences positioned the korarchaeote as a deep archaeal lineage with an apparent affinity to the Crenarchaeota. However, the predicted gene content revealed that several conserved cellular systems, such as cell division, DNA replication, and tRNA maturation, resemble the counterparts in the Euryarchaeota. In light of the known composition of archaeal genomes, the Korarchaeota might have retained a set of cellular features that represents the ancestral archaeal form.

  17. Rebates, loans, and consumers` choice of appliance efficiency level: Combining stated and revealed-preference data

    SciTech Connect (OSTI)

    Train, K.E.; Atherton, T.

    1995-12-31

    Residential customers` choice of efficiency level for appliances, and their participation in demand-side management (DSM) programs, are examined using data on customers` stated preferences in hypothetical (i.e., conjoint-type) situations and their revealed preferences in real-world choices. The analysis provides information on customers` willingness to pay for energy savings, the importance of rebates in customers` decisions, and customers` response to DSM programs that offer loans for purchases of high-efficiency appliances. An estimated model is used to forecast the decisions of customers under: higher rebates, replacement of rebates with finance programs, offering of loans and rebates as alternative options for customers, and the elimination of DSM programs. We find that attractive loans (e.g., low interest rates, loan repayment periods) are necessary to have the same effect as rebates. Programs that offer customers the option of loans or rebates are found to be far more effective than programs that offer only loans or only rebates. 12 refs., 5 figs.

  18. Secrets in the Ancient Goatskins: X-Rays Reveal Archimedes' Oldest Writings

    ScienceCinema (OSTI)

    Bergmann, Uwe [SLAC Linear Accelerator Center, United States

    2010-01-08

    Archimedes of Syracruse (287 - 212 B.C.) is considered one of the most brilliant thinkers of all time. The tenth-century parchment known as the Archimedes Palimpsest is by far the oldest surviving manuscript containing works of Archimedes. it is also the unique source for three of the Greek's treatises: the Stomachion, the Method of Mechanical Theorems, and the Greek version of On Floating Bodies. The privately owned palimpsest is the subject of a integrated campaign of conservation, imaging, and scholarship being undertaken at the Walters Art Museum in Baltimore. Much of the text has been imaged by various optical techniques, but significant gaps in our knowledge of the writing of Archimedes remained. A breakthrough in uncovering the missing Archimedes writings was achieved at the Stanford Synchrotron Radiation Laboratory. Using x-ray fluorescence imaging, writings from faint traces of the partly erased iron gall ink were brought to light. The x-ray image revealed Archimedes writings from some of his most important works covered by twelfth-century biblical texts and twentieth-century gold forgeries. This talk will focus on the fascinating journal of a 1,000 year old parchment from its origin in the Mediterranean city of Constantinople to an x-ray beamline at SLAC.

  19. Structure analysis reveals the flexibility of the ADAMTS-5 active site

    SciTech Connect (OSTI)

    Shieh, Huey-Sheng; Tomasselli, Alfredo G.; Mathis, Karl J.; Schnute, Mark E.; Woodard, Scott S.; Caspers, Nicole; Williams, Jennifer M.; Kiefer, James R.; Munie, Grace; Wittwer, Arthur; Malfait, Anne-Marie; Tortorella, Micky D.

    2012-03-02

    A ((1S,2R)-2-hydroxy-2,3-dihydro-1H-inden-1-yl) succinamide derivative (here referred to as Compound 12) shows significant activity toward many matrix metalloproteinases (MMPs), including MMP-2, MMP-8, MMP-9, and MMP-13. Modeling studies had predicted that this compound would not bind to ADAMTS-5 (a disintegrin and metalloproteinase with thrombospondin motifs-5) due to its shallow S1' pocket. However, inhibition analysis revealed it to be a nanomolar inhibitor of both ADAMTS-4 and -5. The observed inconsistency was explained by analysis of crystallographic structures, which showed that Compound 12 in complex with the catalytic domain of ADAMTS-5 (cataTS5) exhibits an unusual conformation in the S1' pocket of the protein. This first demonstration that cataTS5 can undergo an induced conformational change in its active site pocket by a molecule like Compound 12 should enable the design of new aggrecanase inhibitors with better potency and selectivity profiles.

  20. Do Energy Efficiency Standards Improve Quality? Evidence from a Revealed Preference Approach

    SciTech Connect (OSTI)

    Houde, Sebastien; Spurlock, C. Anna

    2015-06-01

    Minimum energy efficiency standards have occupied a central role in U.S. energy policy for more than three decades, but little is known about their welfare effects. In this paper, we employ a revealed preference approach to quantify the impact of past revisions in energy efficiency standards on product quality. The micro-foundation of our approach is a discrete choice model that allows us to compute a price-adjusted index of vertical quality. Focusing on the appliance market, we show that several standard revisions during the period 2001-2011 have led to an increase in quality. We also show that these standards have had a modest effect on prices, and in some cases they even led to decreases in prices. For revision events where overall quality increases and prices decrease, the consumer welfare effect of tightening the standards is unambiguously positive. Finally, we show that after controlling for the effect of improvement in energy efficiency, standards have induced an expansion of quality in the non-energy dimension. We discuss how imperfect competition can rationalize these results.