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Beyond Spin-Orbit: Probing Electron Correlation in the Pu 5f States

Description: Experiments planned to address the issue of electron correlation in the Pu 5f states are described herein. The key is the utilization of the Fano Effect, the observation of spin polarization in nonmagnetic systems, using chiral excitation such as circularly polarized X-rays.
Date: May 8, 2006
Creator: Tobin, J G
Partner: UNT Libraries Government Documents Department
open access

Numerical Modeling of CO2 Sequestration in Geologic Formations - Recent Results and Open Challenges

Description: Rising atmospheric concentrations of CO2, and their role inglobal warming, have prompted efforts to reduce emissions of CO2 fromburning of fossil fuels. An attractive mitigation option underconsideration in many countries is the injection of CO2 from stationarysources, such as fossil-fueled power plants, into deep, stable geologicformations, where it would be stored and kept out of the atmosphere fortime periods of hundreds to thousands of years or more. Potentialgeologic storage reservoirs inc… more
Date: March 8, 2006
Creator: Pruess, Karsten
Partner: UNT Libraries Government Documents Department
open access

Effect of pressure on the crystal structure of ettringite

Description: X-ray diffraction and infrared data have been collected froma sample of ettringite from ambient pressure to 6.4 GPa. The sample wasfound to reversibly transform to an amorphous phase at 3 GPa. Theisothermal bulk modulus of ettringite was found to be 27(7) GPa and theincompressibilities of the lattice parameters were found to be 71(30) GPaalong a and 108(36) GPa along c.
Date: December 8, 2006
Creator: Clark, Simon M.; Colas, Bruno; Kunz, Martin; Speziale, Sergio & Monteiro, Paulo J.M.
Partner: UNT Libraries Government Documents Department
open access

Random polycrystals of grains containing cracks: Model ofquasistatic elastic behavior for fractured systems

Description: A model study on fractured systems was performed using aconcept that treats isotropic cracked systems as ensembles of crackedgrains by analogy to isotropic polycrystalline elastic media. Theapproach has two advantages: (a) Averaging performed is ensembleaveraging, thus avoiding the criticism legitimately leveled at mosteffective medium theories of quasistatic elastic behavior for crackedmedia based on volume concentrations of inclusions. Since crack effectsare largely independent of the volume … more
Date: July 8, 2006
Creator: Berryman, James G. & Grechka, Vladimir
Partner: UNT Libraries Government Documents Department
open access

A QR accelerated volume-to-surface boundary condition for finite element solution of eddy current problems

Description: We are concerned with the solution of time-dependent electromagnetic eddy current problems using a finite element formulation on three-dimensional unstructured meshes. We allow for multiple conducting regions, and our goal is to develop an efficient computational method that does not require a computational mesh of the air/vacuum regions. This requires a sophisticated global boundary condition specifying the total fields on the conductor boundaries. We propose a Biot-Savart law based volume-to-… more
Date: September 8, 2006
Creator: White, D; Fasenfest, B; Rieben, R & Stowell, M
Partner: UNT Libraries Government Documents Department
open access

Density changes in Ga-stabilized delta-Pu, and what they mean

Description: Ga-stabilized {delta}-Pu undergoes small changes in density with time. These have been associated with four different causes: an initial reversible expansion that saturates after a short time; a continuous change that can be attributed to the in-growth of helium and actinide daughter products from the radioactive decay of plutonium; possible void swelling; and phase instability. We review our present understanding of these processes and evaluate their contributions to density changes. It is sho… more
Date: September 8, 2006
Creator: G.Wolfer, W.; Kubota, A.; S?derlind, P.; Landa, A.; Oudot, B.; Sadigh, B. et al.
Partner: UNT Libraries Government Documents Department
open access

Enhancement of Spin-Polarized Electron Emission from Strain-Compensated AlInGaAs-GaAsP Superlattices

Description: Resonance enhancement of the quantum efficiency of new polarized electron photocathodes based on a short-period strain-compensated AlInGaAs/GaAsP superlattice structure is reported. The superlattice is a part of an integrated Fabry-Perot optical cavity. We demonstrate that the Fabry-Perot resonator enhances the quantum efficiency by up to a factor 10 in the wavelength region of the main polarization maximum. The high structural quality implied by these results points to the very promising appli… more
Date: December 8, 2006
Creator: Roberts, J. S.; Yashin, Yu. P.; Mamaev, Yu. A.; Gerchikov, L. G.; Maruyama, T.; Luh, D. -A. et al.
Partner: UNT Libraries Government Documents Department
open access

A New Stabilized Nodal Integration Approach

Description: A new stabilized nodal integration scheme is proposed and implemented. In this work, focus is on the natural neighbor meshless interpolation schemes. The approach is a modification of the stabilized conforming nodal integration (SCNI) scheme and is shown to perform well in several benchmark problems.
Date: February 8, 2006
Creator: Puso, M; Zywicz, E & Chen, J S
Partner: UNT Libraries Government Documents Department
open access

A general scaling relation for the critical current density inNb3Sn

Description: We review the scaling relations for the critical currentdensity (Jc) in Nb3Sn wires and include recent findings on the variationof the upper critical field (Hc2) with temperature (T) and A15composition. Measurements of Hc2(T) in inevitably inhomogeneous wires, aswell as analysis of literature results, have shown that all availableHc2(T) data can be accurately described by a single relation from themicroscopic theory. This relation also holds for inhomogeneity averaged,effective, Hc2*(T) results… more
Date: May 8, 2006
Creator: Godeke, A.; Haken, B. ten; Kate, H.H.J. ten & Larbalestier, D.C.
Partner: UNT Libraries Government Documents Department
open access

Intensity-based signal separation algorithm for accuratequantification of clustered centrosomes in tissue sections

Description: Centrosomes are small organelles that organize the mitoticspindle during cell division and are also involved in cell shape andpolarity. Within epithelial tumors, such as breast cancer, and somehematological tumors, centrosome abnormalities (CA) are common, occurearly in disease etiology, and correlate with chromosomal instability anddisease stage. In situ quantification of CA by optical microscopy ishampered by overlap and clustering of these organelles, which appear asfocal structures. CA has … more
Date: March 8, 2006
Creator: Fleisch, Markus C.; Maxell, Christopher A.; Kuper, Claudia K.; Brown, Erika T.; Parvin, Bahram; Barcellos-Hoff, Mary-Helen et al.
Partner: UNT Libraries Government Documents Department
open access

Scaling Properties of Hyperon Production in Au + Au Collisions at sqrt sNN = 200 GeV

Description: We present the scaling properties of Lambda, Xi, and their anti-particles produced at mid-rapidity in Au+Au collisions at RHIC at psNN = 200 GeV. The yield of multi-strange baryons per participant nucleon increases from peripheral to central collisions more rapidly than the Lambda yield, which appears to correspond to an increasing strange quark density of matter produced. The value of the strange phase space occupancy factor gamma s, obtained from a thermal model fit to the data, approaches un… more
Date: June 8, 2006
Creator: Adams, J.
Partner: UNT Libraries Government Documents Department
open access

A general scaling relation for the critical current density inNb3Sn

Description: We review the scaling relations for the critical currentdensity (Jc) in Nb3Sn wires and include recent findings on the variationof the upper critical field (Hc2) with temperature (T) and A15composition. Measurements of Hc2(T) in inevitably inhomogeneous wires, aswell as analysis of literature results, have shown that all availableHc2(T) data can be accurately described by a single relation from themicroscopic theory. This relation also holds for inhomogeneity averaged,effective, Hc2*(T) results… more
Date: May 8, 2006
Creator: Godeke, A.; Haken, B. ten; Kate, H.H.J. ten & Larbalestier, D.C.
Partner: UNT Libraries Government Documents Department
open access

The Evolution of Ga and As Core Levels in the Formation of Fe/GaAs(001): A High Resolution Soft X-ray Photoelectron Spectroscopic Study

Description: A high resolution soft x-ray photoelectron spectroscopic study of Ga and As 3d core levels has been conducted for Fe/GaAs (001) as a function of Fe thickness. This work has provided unambiguous evidence of substrate disrupting chemical reactions induced by the Fe overlayer--a quantitative analysis of the acquired spectra indicates significantly differing behavior of Ga and As during Fe growth, and our observations have been compared with existing theoretical models. Our results demonstrate that… more
Date: December 8, 2006
Creator: Thompson, J W; Neal, J R; Shen, T H; Morton, S A; Tobin, J G; Waddill, G D et al.
Partner: UNT Libraries Government Documents Department
open access

Cryogenic Neutron Spectrometer Development

Description: Cryogenic microcalorimeter detectors operating at temperatures around {approx}0.1 K have been developed for the last two decades, driven mostly by the need for ultra-high energy resolution (<0.1%) in X-ray astrophysics and dark matter searches [1]. The Advanced Detector Group at Lawrence Livermore National Laboratory has developed different cryogenic detector technologies for applications ranging from X-ray astrophysics to nuclear science and non-proliferation. In particular, we have adapted… more
Date: March 8, 2006
Creator: Niedermayr, T.; Hau, I. D.; Friedrich, S.; Burger, A.; Roy, U. N. & Bell, Z. W.
Partner: UNT Libraries Government Documents Department
open access

BlueGene/L Applications: Parallelism on a Massive Scale

Description: BlueGene/L (BG/L), developed through a partnership between IBM and Lawrence Livermore National Laboratory (LLNL), is currently the world's largest system both in terms of scale with 131,072 processors and absolute performance with a peak rate of 367 TFlop/s. BG/L has led the Top500 list the last four times with a Linpack rate of 280.6 TFlop/s for the full machine installed at LLNL and is expected to remain the fastest computer in the next few editions. However, the real value of a machine like … more
Date: September 8, 2006
Creator: de Supinski, B. R.; Schulz, M.; Bulatov, V. V.; Cabot, W.; Chan, B.; Cook, A. W. et al.
Partner: UNT Libraries Government Documents Department
open access

Long Term Electrochemical Behavior of Creviced and Non-Creviced Alloy 22 in CaCl2 + Ca(NO3)2 Brines at 155?C

Description: Alloy 22 is a nickel base alloy highly resistant to all forms of corrosion. In very aggressive conditions (e.g. hot concentrated chloride containing brines) Alloy 22 could suffer localized attack, namely pitting and crevice corrosion. Chloride ion is known to be the most detrimental aggressive agent for Alloy 22 and is able to promote crevice corrosion when tight crevices exist in hot chloride containing solutions of different concentrations. Nitrate ion is an effective inhibitor of chloride in… more
Date: November 8, 2006
Creator: Rodriguez, M. A.; Stuart, M. L. & Rebak, R. B.
Partner: UNT Libraries Government Documents Department
open access

Crevice Repassivation Potentials for Alloy 22 in Simulated Concentrated Ground Waters

Description: The resistance of Alloy 22 (N06022) to localized corrosion, mainly crevice corrosion, has been extensively investigated in the last few years. However, the behavior of Alloy 22 in concentrated aqueous solutions that may simulate concentrated ground waters was not fully understood. Systematic electrochemical tests using cyclic potentiodynamic polarization as well as the Tsujikawa-Hisamatsu electrochemical method were performed to determine the crevice corrosion susceptibility of Alloy 22 in simu… more
Date: November 8, 2006
Creator: Rebak, R B; Evans, K J & Ilevbare, G O
Partner: UNT Libraries Government Documents Department
open access

A Monte Carlo Model for Interrogation of Thick Cargos for Clandestine Fissionable Materials; Tests with 14-MeV Neutrons

Description: A Monte Carlo model has been developed for interrogation of fissionable material embedded in thick cargos when high-energy {beta}-delayed {gamma} rays are detected following neutron-induced fission. The model includes the principal structural components of the laboratory, the neutron source and collimator assembly in which it resides, the assembly that represents cargo of given characteristics, a target of highly-enriched uranium (HEU) and large external plastic scintillators for photon detecti… more
Date: June 8, 2006
Creator: Prussin, S.; Descalle, M.; Hall, J.; Pruet, J.; Slaughter, D.; Accatino, M. et al.
Partner: UNT Libraries Government Documents Department
open access

The Velocity Field of the Local Universe From Measurements of Type Ia Supernovae

Description: We present a measurement of the velocity flow of the local universe relative to the CMB rest frame, based on the Jha, Riess & Kirshner (2007) sample of 133 low redshift type Ia supernovae. At a depth of 4500 km s{sup -1} we find a dipole amplitude of 279 {+-} 68 km s{sup -1} in the direction l = 285{sup o} {+-} 18{sup o}, b = -10{sup o} {+-} 15{sup o}, consistent with earlier measurements and with the assumption that the local velocity field is dominated by the Great Attractor region. At a larg… more
Date: December 8, 2006
Creator: Haugbolle, T.; Hannestad, S.; Thomsen, B.; U., /Aarhus; Fynbo, J.; Inst., /Bohr et al.
Partner: UNT Libraries Government Documents Department
open access

Improved Superlattices for Spin-Polarized Electron Sources

Description: Photoemission of polarized electrons from heterostructures based on InAlGaAs/GaAs superlattices with minimum conduction-band offsets is investigated. The comparison of the excitation energy dependence of the photoemission polarization degree with the calculated spectra makes it possible to determine the polarization losses at different stages of the photoemission. A maximum polarization of P = 91% and a quantum efficiency of QE = 0.5% are close to the best results obtained for photocathodes tha… more
Date: December 8, 2006
Creator: Mamaev, Yu. A.; Gerchikov, L. G.; Yashin, Yu. P.; Kuz-michev, V.; Vasiliev, D.; Maruymama, T. et al.
Partner: UNT Libraries Government Documents Department
open access

Integrating Ontological Knowledge and Textual Evidence in Estimating Gene and Gene Product Similarity

Description: With the rising influence of the Gene On-tology, new approaches have emerged where the similarity between genes or gene products is obtained by comparing Gene Ontology code annotations associ-ated with them. So far, these approaches have solely relied on the knowledge en-coded in the Gene Ontology and the gene annotations associated with the Gene On-tology database. The goal of this paper is to demonstrate that improvements to these approaches can be obtained by integrating textual evidence ext… more
Date: June 8, 2006
Creator: Sanfilippo, Antonio P.; Posse, Christian; Gopalan, Banu; Tratz, Stephen C. & Gregory, Michelle L.
Partner: UNT Libraries Government Documents Department
open access

U.S. MOPEX DATA SET

Description: A key step in applying land surface parameterization schemes is to estimate model parameters that vary spatially and are unique to each computational element. Improved methods for parameter estimation (especially for parameters important to runoff response) are needed and require data from a wide range of climate regimes throughout the world. Accordingly, the GEWEX Hydrometeorology Panel (GHP) endorsed the concept of an international Model Parameter Estimation Project (MOPEX) at its Toronto mee… more
Date: May 8, 2006
Creator: Schaake, J; Cong, S & Duan, Q
Partner: UNT Libraries Government Documents Department
open access

Probing Dark Energy with Constellation-X

Description: Constellation-X (Con-X) will carry out two powerful and independent sets of tests of dark energy based on X-ray observations of galaxy clusters, providing comparable accuracy to other leading dark energy probes. The first group of tests will measure the absolute distances to clusters, primarily using measurements of the X-ray gas mass fraction in the largest, dynamically relaxed clusters, but with additional constraining power provided by follow-up observations of the Sunyaev-Zel'dovich (SZ) ef… more
Date: September 8, 2006
Creator: Rapetti, David; Allen, Steven W. & /KIPAC, Menlo Park
Partner: UNT Libraries Government Documents Department
open access

Energy Amplification and Beam Bunching in a Pulse Line Ion Accelerator

Description: In a first beam dynamics validation experiment for a new Pulse Line Ion Acceleration (PLIA) concept, the predicted energy amplification and beam bunching were experimentally observed. Beam energy modulation of -80 keV to +150 keV was measured using a PLIA input voltage waveform of -21 kV to +12 kV. Ion pulses accelerated by 150 keV, and bunching by a factor of four were simultaneously achieved. The measured longitudinal phase space and current waveform of the accelerated beam are in good agreem… more
Date: June 8, 2006
Creator: Roy, P. K.; Waldron, W. L.; Yu, S. S.; Coleman, J. E.; Henestroza, E.; Grote, D. P. et al.
Partner: UNT Libraries Government Documents Department
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