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Electronic structure effects in liquid water studied by photoelectron spectroscopy and density functional theory

Description: We present valence photoelectron emission spectra of liquid water in comparison with gas-phase water, ice close to the melting point, low temperature amorphous and crystalline ice. All aggregation states have major electronic structure changes relative to the free molecule, with rehybridization and development of bonding and anti-bonding states accompanying the hydrogen bond formation. Sensitivity to the local structural order, most prominent in the shape and splitting of the occupied 3a{sub 1}… more
Date: April 29, 2008
Creator: Nordlund, Dennis; Odelius, Michael; Bluhm, Hendrik; Ogasawara, Hirohito; Pettersson, Lars G.M. & Nilsson, Anders
Partner: UNT Libraries Government Documents Department
open access

Worldlines as Wilson Lines

Description: Gravitational theories do not admit gauge invariant local operators. We study the limits under which there exists a quasi-local description for a class of non-local gravitational observables where a sum over worldlines plays the role of the Wilson line for gauge theory observables. We study non-local corrections to the local description and circumstances where these corrections become large. We find that these operators are quasi-local in at space and AdS, but fail to be quasi-local in de Sitte… more
Date: April 29, 2008
Creator: Green, Daniel & /SLAC /Stanford U., Dept. Phys.
Partner: UNT Libraries Government Documents Department
open access

Dirac charge dynamics in graphene by infrared spectroscopy

Description: A remarkable manifestation of the quantum character of electrons in matter is offered by graphene, a single atomic layer of graphite. Unlike conventional solids where electrons are described with the Schrödinger equation, electronic excitations in graphene are governed by the Dirac hamiltonian. Some of the intriguing electronic properties of graphene, such as massless Dirac quasiparticles with linear energy-momentum dispersion, have been confirmed by recent observations. Here, we report an… more
Date: April 29, 2008
Creator: Martin, Michael C.; Li, Z. Q.; Henriksen, E. A.; Jiang, Z.; Hao, Z.; Martin, Michael C et al.
Partner: UNT Libraries Government Documents Department
open access

Repair of radiation-induced heat-labile sites is independent of DNA-PKcs, XRCC1 or PARP

Description: Ionizing radiation induces a variety of different DNA lesions: in addition to the most critical DNA damage, the DSB, numerous base alterations, SSBs and other modifications of the DNA double-helix are formed. When several non-DSB lesions are clustered within a short distance along DNA, or close to a DSB, they may interfere with the repair of DSBs and affect the measurement of DSB induction and repair. We have previously shown that a substantial fraction of DSBs measured by pulsed-field gel elec… more
Date: April 29, 2008
Creator: Stenerlöw, Bo; Karlsson, Karin H.; Radulescu, Irina; Rydberg, Bjorn & Stenerlow, Bo
Partner: UNT Libraries Government Documents Department
open access

Triple Differential Cross sections and Nuclear Recoil in Two-Photon Double Ionization of Helium

Description: Triple differential cross sections (TDCS) for two-photon double ionization of helium are calculated using the method of exterior complex scaling both above and below the threshold for sequential ionization (54.4 eV). It is found that sequential ionization produces characteristic behavior in the TDCS that identifies that process when it is in competition with nonsequential ionization. Moreover we see the signature in the TDCS and nuclear recoil cross sections of"virtual sequential ionizatio… more
Date: April 29, 2008
Creator: Horner, Daniel A.; McCurdy, C. William & Rescigno, Thomas N
Partner: UNT Libraries Government Documents Department
open access

A pulsed-laser calibration system for the laser backscatter diagnostics at the Omega laser

Description: A calibration system has been developed that allows a direct determination of the sensitivity of the laser backscatter diagnostics at the Omega laser. A motorized mirror at the target location redirects individual pulses of a mJ-class laser onto the diagnostic to allow the in-situ measurement of the local point response of the backscatter diagnostics. Featuring dual wavelength capability at the 2nd and 3rd harmonic of the Nd:YAG laser, both spectral channels of the backscatter diagnostics can b… more
Date: April 29, 2008
Creator: Neumayer, P.; Sorce, C.; Froula, D. H.; Rekow, V.; Loughman, K.; Knight, R. et al.
Partner: UNT Libraries Government Documents Department
open access

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

Description: 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 signif… more
Date: April 29, 1991
Creator: Haghighi, H.; Kaiser, J. H.; Rayner, S. L.; West, R. N.; Liu, J. Z.; Shelton, R. et al.
Partner: UNT Libraries Government Documents Department
open access

Saturation and kinetic issues for optical-field-ionized plasma x-ray lasers

Description: Lasing between excited states and the ground state following optical-field ionization is studied. Saturation of an x-ray laser when the lower lasing level is a ground state of a H-like or Li-like ion is discussed. Efficiencies of 10{sup {minus}5} to 10{sup {minus}4} are calculated for the 3d{sub 5/2}--2p{sub 3/2} transition at 98 {Angstrom} in Li-like Ne. The assumption that the fine-structure levels are populated according to their statistical weights is shown to be justified through compariso… more
Date: April 29, 1991
Creator: Eder, D.C.; Amendt, P.; Rosen, M.D.; Nash, J.K. & Wilks, S.C.
Partner: UNT Libraries Government Documents Department
open access

Martin Marietta Energy Systems Nuclear Criticality Safety Improvement Program

Description: This report addresses questions raised by criticality safety violation at several DOE plants. Two charts are included that define the severity and reporting requirements for the six levels of accidents. A summary is given of all reported criticality incident at the DOE plants involved. The report concludes with Martin Marietta's Nuclear Criticality Safety Policy Statement. (JDH)
Date: April 29, 1987
Creator: Speas, I.G.
Partner: UNT Libraries Government Documents Department
open access

Plasma confinement in the TMX tandem mirror

Description: Plasma confinement in the Tandem Mirror Experiment (TMX) is described. Axially confining potentials are shown to exist throughout the central 20-cm core of TMX. Axial electron-confinement time is up to 100 times that of single-cell mirror machines. Radial transport of ions is smaller than axial transport near the axis. It has two parts at large radii: nonambipolar, in rough agreement with predictions from resonant-neoclassical transport theory, and ambipolar, observed near the plasma edge under… more
Date: April 29, 1981
Creator: Hooper, E. B. Jr.; Allen, S. L. & Casper, T. A.
Partner: UNT Libraries Government Documents Department
open access

Energetic materials destruction using molten salt

Description: The Lawrence Livermore National Laboratory in conjunction with the Energetic Materials Center is developing methods for the safe and environmentally sound destruction of explosives and propellants as a part of the Laboratory`s ancillary demilitarization mission. LLNL has built a small-scale unit to test the destruction of HE using the Molten Salt Destruction (MSD) Process. In addition to the high explosive HMX, destruction has been carried out on RDX, PETN, ammonium picrate, TNT, nitroguanadine… more
Date: April 29, 1994
Creator: Upadhye, R. S.; Watkins, B. E.; Pruneda, C. O. & Brummond, W. A.
Partner: UNT Libraries Government Documents Department
open access

Studies of laser-driven radiative blast waves

Description: We have performed two sets of experiments looking at laser-driven radiating blast waves. In one set of experiments the effect of a drive laser's passage through a background gas on the hydrodynamical evolution of blast waves was examined. It was found that the laser's passage heats a channel in the gas, creating a region where a portion of the blast wave front had an increased velocity, leading to the formation of a bump-like protrusion on the blast wave. The second set of experiments involved … more
Date: April 29, 2004
Creator: Edwards, M J; Hansen, J; Edens, A; Ditmire, T; Adams, R; Rambo, P et al.
Partner: UNT Libraries Government Documents Department
open access

Verification & Validation: Goals, Methods, Levels, and Metrics

Description: This work briefly summarizes the current status of the V and V Program at LLNL regarding goals, methods, timelines, and issues for Verification and Validation (V and V) with Uncertainty Quantification (UQ). The goals are to evaluate various V and V methods, to apply them to computational simulation analyses, and integrate them into methods for Quantitative Certification techniques for the nuclear stockpile. Methods include qualitative and quantitative V and V processes with numerical values for… more
Date: April 29, 2003
Creator: Logan, R W & Nitta, C K
Partner: UNT Libraries Government Documents Department
open access

Generalized ponderomotive forces and three-wave interaction

Description: A unified Hamiltonian approach to the theory of nonlinear interactions among waves and particles is discussed. The unifying feature of the approach is a generalization of the concept of pondermotive force. The usual method of time averaging is replaced by a canonical transformation. The transformation is designed to eliminate the terms in the Hamiltonian of a particle which are linear in the wave potentials, replacing them with bilinear terms at combination frequencies. An oscillation center ap… more
Date: April 29, 1976
Creator: Johnston, S. & Kaufman, A. N.
Partner: UNT Libraries Government Documents Department
open access

On the Performance of an Algebraic MultigridSolver on Multicore Clusters

Description: Algebraic multigrid (AMG) solvers have proven to be extremely efficient on distributed-memory architectures. However, when executed on modern multicore cluster architectures, we face new challenges that can significantly harm AMG's performance. We discuss our experiences on such an architecture and present a set of techniques that help users to overcome the associated problems, including thread and process pinning and correct memory associations. We have implemented most of the techniques in a … more
Date: April 29, 2010
Creator: Baker, A H; Schulz, M & Yang, U M
Partner: UNT Libraries Government Documents Department
open access

Integrated genomic and transcriptomic analysis reveals mycoparasitism as the ancestoral life style of Trichoderma

Description: Mycoparasitism, a lifestyle where one fungus is parasitic on another fungus has special relevance when the prey is a plant pathogen, providing a strategy for biological control of pests for plant protection. Probably, the most studied biocontrol agents are species of the genus Hypocrea/Trichoderma.
Date: April 29, 2011
Creator: Kubicek, Christian P.; Herrera-Estrella, Alfredo; Seidl, Verena; Le Crom, Stéphane; Martinez, Diego A.; Druzhinina, Irina S. et al.
Partner: UNT Libraries Government Documents Department
open access

Finite temperature spin-dynamics and phase transitions in spin-orbital models

Description: We study finite temperature properties of a generic spin-orbital model relevant to transition metal compounds, having coupled quantum Heisenberg-spin and Ising-orbital degrees of freedom. The model system undergoes a phase transition, consistent with that of a 2D Ising model, to an orbitally ordered state at a temperature set by short-range magnetic order. At low temperatures the orbital degrees of freedom freeze-out and the model maps onto a quantum Heisenberg model. The onset of orbital excit… more
Date: April 29, 2010
Creator: Chen, C. C.
Partner: UNT Libraries Government Documents Department
open access

Tunneling density of states as a function of thickness in superconductor/ strong ferromagnet bilayers

Description: We have made an experimental study of the tunneling density of states (DOS) in strong ferromagnetic thin films (CoFe) in proximity with a thick superconducting film (Nb) as a function of d{sub F}, the ferromagnetic thickness. Remarkably, we find that as d{sub F} increases, the superconducting DOS exhibits a scaling behavior in which the deviations from the normal-state conductance have a universal shape that decreases exponentially in amplitude with characteristic length d* {approx} 0.4 nm. We … more
Date: April 29, 2010
Creator: Reymond, S.
Partner: UNT Libraries Government Documents Department
open access

A Southern Sky Survey with Fermi LAT and ASKAP

Description: 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… more
Date: April 29, 2010
Creator: Cameron, Robert A. & /SLAC /KIPAC, Menlo Park
Partner: UNT Libraries Government Documents Department
open access

Origin of charge density at LaAlO3-on-SrTiO3 heterointerfacespossibility of intrinsic doping

Description: As discovered by Ohtomo et al., a large sheet charge density with high mobility exists at the interface between SrTiO{sub 3} and LaAlO{sub 3}. Based on transport, spectroscopic and oxygen-annealing experiments, we conclude that extrinsic defects in the form of oxygen vacancies introduced by the pulsed laser deposition process used by all researchers to date to make these samples is the source of the large carrier densities. Annealing experiments show a limiting carrier density. We also present … more
Date: April 29, 2010
Creator: Siemons, W.
Partner: UNT Libraries Government Documents Department
open access

Cyclotron Resonances in Electron Cloud Dynamics

Description: A new set of resonances for electron cloud dynamics in the presence of a magnetic field has been found. For short beam bunch lengths and low magnetic fields where lb<< 2pi c/omega c (with lb = bunch length, omega c = non-relativistic cyclotron frequency) resonances between the bunch frequency and harmonics of the electron cyclotron frequency cause an increase in the electron cloud density in narrow ranges of magnetic field near the resonances. For ILC parameters the increase in the densit… more
Date: April 29, 2009
Creator: Celata, C. M.; Furman, Miguel A.; Vay, J. L.; Ng, J. S. T.; Grote, D. P.; Pivi, M. T. F. et al.
Partner: UNT Libraries Government Documents Department
open access

Quasi-zero dimensional CuB2O4: a resonant inelastic X-ray scattering case study

Description: We explore the general phenomenology of resonant inelastic scattering (RIXS) using CuB{sub 2}O{sub 4}, a network of CuO{sub 4} plaquettes electronically isolated by B{sup +3} ions. Spectra show a small number of well-separated features, and we exploit the simple electronic structure to explore RIXS phenomenology by developing a calculation which allows for intermediate-state effects ignored in standard approaches. These effects are found to be non-negligible and good correspondence between our … more
Date: April 29, 2010
Creator: Hancock, J.N.
Partner: UNT Libraries Government Documents Department
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