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Edmonds et al. Reply

Description: This article is a response to an article by M. Adell et al. [Phy. Rev. Lett. 94, 139701 (2005)] about semiconductor-based spintronics research.
Date: April 8, 2005
Creator: Edmonds, Kevin; Boguslawski, Piotr; Wang, K. Y.; Campion, Richard Paul; Novikov, Sergei; Farley, N. R. S. et al.
Partner: UNT College of Arts and Sciences
open access

Field investigation of the drift shadow

Description: A drift shadow is an area immediately beneath an undergroundvoidthat, in theory, will be relatively drier than the surrounding rockmass. Numerical and analytical models of water flow through unsaturatedrock predict the existence of a drift shadow, but field tests confirmingits existence have yet to be performed. Proving the existence of driftshadows and understanding their hydrologic and transport characteristicscould provide a better understanding of how contaminants move in thesubsurface if r… more
Date: September 8, 2005
Creator: Su, Grace W.; Kneafsey, Timothy J.; Ghezzehei, Teamrat A.; Marshall, Brian D. & Cook, Paul J.
Partner: UNT Libraries Government Documents Department
open access

HOT ELECTRON ENERGY DISTRIBUTIONS FROM ULTRA-INTENSE LASER SOLID INTERACTIONS

Description: We present experimental data of electron energy distributions from ultra-intense (>10{sup 19} W/cm{sup 2}) laser-solid interactions using the Rutherford Appleton Laboratory Vulcan petawatt laser. These measurements were made using a CCD-based magnetic spectrometer. We present details on the distinct effective temperatures that were obtained for a wide variety of targets as a function of laser intensity. It is found that as the intensity increases from 10{sup 17} W/cm{sup 2} to 10{sup 19} W/c… more
Date: December 8, 2005
Creator: Chen, H; Wilks, S C; Kruer, W L; Moon, S; Patel, N; Patel, P K et al.
Partner: UNT Libraries Government Documents Department
open access

Z-Beamlet (ZBL) Multi-Frame Back-lighter (MFB) System for ICF/Plasma Diagnostics

Description: Z-Beamlet [1] is a single-beam high-energy Nd:glass laser used for backlighting high energy density (HED) plasma physics experiments at Sandia's Z-accelerator facility. The system currently generates a single backlit image per experiment, and has been employed on approximately 50% of Z-accelerator system shots in recent years. We have designed and are currently building a system that uses Z-Beamlet to generate two distinct backlit images with adjustable time delay ranging from 2 to 20 ns betwee… more
Date: September 8, 2005
Creator: Caird, J A; Erlandson, A C; Molander, W A; Murray, J E; Robertson, G K; Smith, I C et al.
Partner: UNT Libraries Government Documents Department
open access

A Molecular Assessment of Phylogenetic Relationships and LineageDiversification Within the Family Salamandridae (Amphibia, Caudata)

Description: Phylogenetic relationships among species of the salamanderfamily Salamandridae are investigated using nearly 3000 nucleotide basesof newly reported mitochondrial DNA sequence data from the mtDNA genicregion spanning the genes tRNALeu-COI. This study uses nearlycomprehensive species-level sampling to provide the first completephylogeny for the Salamandridae. Deep phylogenetic relationships amongthe three most divergent lineages in the family Salamandrina terdigitata,a clade comprising the "True"… more
Date: August 8, 2005
Creator: Weisrock, David W.; Papenfuss, Theodore J.; Macey, J. Robert; Litvinchuk, Spartak N.; Polymeni, Rosa; Ugurtas, Ismail H. et al.
Partner: UNT Libraries Government Documents Department
open access

Coordination Complexes of Decamethylytterbocene with4,4'-Disubstituted Bipyridines: An Experimental Study of Spin Coupling inLanthanide Complexes

Description: The paramagnetic 1:1 coordination complexes of (C5Me5)2Ybwith a series of 4,4'-disubstituted bipyridines, bipy-X, where X is Me,tert-Bu, OMe, Ph, CO2Me, and CO2Et have been prepared. All of thecomplexes are paramagnetic and the values of the magnetic susceptibilityas a function of temperature show that these values are less thanexpected for the cation, [(C5Me5)2Yb(III)(bipy-X)]+, which have beenisolated as the cation-anion ion-pairs[(C5Me5)2Yb(III)(bipy-X)]+[(C5Me5)2YbI2]f fnfn where X is CO2Et… more
Date: December 8, 2005
Creator: Walter, Marc D.; Berg, David J. & Andersen, Richard A.
Partner: UNT Libraries Government Documents Department
open access

Progress Toward the Analysis of the Kinetic Stabilizer Concept

Description: The Kinetic Stabilizer (K-S) concept [1] represents a means for stabilizing axisymmetric mirror and tandem-mirror (T-M) magnetic fusion systems against MHD interchange instability modes. Magnetic fusion research has given us examples of axisymmetric mirror confinement devices in which radial transport rates approach the classical ''Spitzer'' level, i.e. situations in which turbulence if present at all, is at too low a level to adversely affect the radial transport [2,3,4]. If such a low-turbule… more
Date: February 8, 2005
Creator: Post, R. F.; Byers, J. A.; Cohen, R. H.; Fowler, T. K.; Ryutov, D. D. & Tung, L. S.
Partner: UNT Libraries Government Documents Department
open access

Integrated Surface-groundwater Flow Modeling: a Free-surface Overland Flow Boundary Condition in a Parallel Groundwater Flow Model

Description: Interactions between surface and ground water are a key component of the hydrologic budget on the watershed scale. Models that honor these interactions are commonly based on the conductance concept that presumes a distinct interface at the land surface, separating the surface from the subsurface domain. These types of models link the subsurface and surface domains via an exchange flux that depends upon the magnitude and direction of the hydraulic gradient across the interface and a proportional… more
Date: April 8, 2005
Creator: Kollet, S J & Maxwell, R M
Partner: UNT Libraries Government Documents Department
open access

Multiband GaNAsP Quaternary Alloys

Description: We have synthesized GaN{sub x}As{sub 1-y}P{sub y} alloys (x {approx} 0.3-1% and y = 0-0.4) using nitrogen N ion implantation into GaAsP epilayers followed by pulsed laser melting and rapid thermal annealing techniques. As predicted by the band anticrossing model, the incorporation of N splits the conduction band (E{sub M}) of the GaAs{sub 1-y}P{sub y} substrate, and strong optical transitions from the valence band to the lower (E{sub -}) and upper (E{sub +}) conduction subbands are observed. Th… more
Date: December 8, 2005
Creator: Yu, K. M.; Walukiewicz, W.; Ager, J. W., III; Bour, D.; Farshchi, R.; Dubon, O. D. et al.
Partner: UNT Libraries Government Documents Department
open access

Using stochastically-generated subcolumns to represent cloud structure in a large-scale model

Description: A new method for representing subgrid-scale cloud structure, in which each model column is decomposed into a set of subcolumns, has been introduced into the Geophysical Fluid Dynamics Laboratory's global climate model AM2. Each subcolumn in the decomposition is homogeneous but the ensemble reproduces the initial profiles of cloud properties including cloud fraction, internal variability (if any) in cloud condensate, and arbitrary overlap assumptions that describe vertical correlations. These su… more
Date: December 8, 2005
Creator: Pincus, R; Hemler, R & Klein, S A
Partner: UNT Libraries Government Documents Department
open access

HUNTing the Overlap

Description: Hiding communication latency is an important optimization for parallel programs. Programmers or compilers achieve this by using non-blocking communication primitives and overlapping communication with computation or other communication operations. Using non-blocking communication raises two issues: performance and programmability. In terms of performance, optimizers need to find a good communication schedule and are sometimes constrained by lack of full application knowledge. In terms of progra… more
Date: July 8, 2005
Creator: Iancu, Costin; Parry, Husbands & Hargrove, Paul
Partner: UNT Libraries Government Documents Department
open access

New Theoretical Insight into the Interactions and Properties of Formic Acid: Development of a Quantum-Based Pair Potential for Formic Acid.

Description: We performed ab initio quantum chemical studies for the development of intra and intermolecular interaction potentials for formic acid for use in molecular dynamics simulations of formic acid molecular crystal. The formic acid structures considered in the ab initio studies include both the cis and trans monomers which are the conformers that have been postulated as part of chains constituting liquid and crystal phases under extreme conditions. Although the cis to trans transformation is not ene… more
Date: August 8, 2005
Creator: Roszak, S; Gee, R; Balasubramanian, K & Fried, L
Partner: UNT Libraries Government Documents Department
open access

Effective Medium Theories for Multicomponent Poroelastic Composites

Description: In Biot's theory of poroelasticity, elastic materials contain connected voids or pores and these pores may be filled with fluids under pressure. The fluid pressure then couples to the mechanical effects of stress or strain applied externally to the solid matrix. Eshelby's formula for the response of a single ellipsoidal elastic inclusion in an elastic whole space to a strain imposed at a distant boundary is a very well-known and important result in elasticity. Having a rigorous generalization o… more
Date: February 8, 2005
Creator: Berger, E. L.
Partner: UNT Libraries Government Documents Department
open access

Molecular Dynamics Simulations of Spinodal-Assisted Polymer Crystallization

Description: Large scale molecular dynamics simulations of bulk melts of polar (poly(vinylidene fluoride) (pVDF)) polymers are utilized to study chain conformation and ordering prior to crystallization under cooling. While the late stages of polymer crystallization have been studied in great detail, recent theoretical and experimental evidence indicates that there are important phenomena occurring in the early stages of polymer crystallization that are not understood to the same degree. When the polymer mel… more
Date: July 8, 2005
Creator: Gee, R H; Lacevic, N M & Fried, L
Partner: UNT Libraries Government Documents Department
open access

Gratings for High-Energy Petawatt Lasers

Description: To enable high-energy petawatt laser operation we have developed the processing methods and tooling that produced both the world's largest multilayer dielectric reflection grating and the world's highest laser damage resistant gratings. We have successfully delivered the first ever 80 cm aperture multilayer dielectric grating to LLNL's Titan Intense Short Pulse Laser Facility. We report on the design, fabrication and characterization of multilayer dielectric diffraction gratings.
Date: November 8, 2005
Creator: Nguyen, H T; Britten, J. A.; Carlson, T. C.; Nissen, J. D.; Summers, L. J.; Hoaglan, C. R. et al.
Partner: UNT Libraries Government Documents Department
open access

The Comparison and Evaluation of Three Fiber Composite Failure Criteria

Description: Three specific failure criteria for the transversely isotropic fiber composite case will be discussed. All three use the polynomial expansion method. The three criteria are the Tsai-Wu criterion, the Hashin criterion and the Christensen criterion. All three criteria will be given in forms that admit direct and easy comparison, which has not usually been done. The central differences between these three criteria will be discussed, and steps will be taken toward the evaluation of them.
Date: February 8, 2005
Creator: Christensen, R M
Partner: UNT Libraries Government Documents Department
open access

The Inductive Coupling of the Magnets in MICE and its Effect on Quench Protection

Description: The inductive coupling between various MICE magnet circuits is described. The consequences of this coupling on magnet charging and quenching are discussed. Magnet quench protection is achieved through the use of quench-back. Calculations of the quenching of a magnet due to quench-back resulting from circulating currents induced in the magnet mandrel due to quenching of an adjacent magnet are discussed. This report describes how the MICE magnet channel will react when magnets in that channel are… more
Date: September 8, 2005
Creator: Green, Michael A. & Witte, Holger
Partner: UNT Libraries Government Documents Department
open access

How the Performance of a Superconducting Magnet Is Affected by the Connection Between a Small Cooler and the Magnet

Description: As low temperature cryocoolers become more frequently used to cool superconducting magnets, it becomes increasingly apparent that the connection between the cooler and the magnet has an effect on the design and performance of the magnet. In general, the use of small coolers can be considered in two different temperature ranges; (1) from 3.8 to 4.8 K for magnet fabricated with LTS conductor and (2) from 18 to 35 K for magnets fabricated using HTS conductor. In general, both temperature ranges ca… more
Date: September 8, 2005
Creator: Green, Michael A.
Partner: UNT Libraries Government Documents Department
open access

Progress on the RF Coupling Coil Module Design for the MICE Channel

Description: We describe the progress on the design of the RF coupling coil (RFCC) module for the international Muon Ionization Cooling Experiment (MICE) at Rutherford Appleton Laboratory (RAL) in the UK. The MICE cooling channel design consists of one SFOFO cell that is similar to that of the US Study-II of a neutrino factory. The MICE RFCC module comprises a superconducting solenoid, mounted around four normal conducting 201.25-MHz RF cavities. Each cavity has a pair of thin curved beryllium windows to cl… more
Date: May 8, 2005
Creator: Li, D.; Green, M. A.; Virostek, S. P.; Zisman, M. S.; Lau, W.; White, A. E. et al.
Partner: UNT Libraries Government Documents Department
open access

Climate Change in Lowland Central America During the Late Deglacial and Early Holocene

Description: The transition from arid glacial to moist early Holocene conditions represented a profound change in northern lowland Neotropical climate. Here we report a detailed record of changes in moisture availability during the latter part of this transition ({approx}11,250 to 7,500 cal yr BP) inferred from sediment cores retrieved in Lake Peten Itza, northern Guatemala. Pollen assemblages demonstrate that a mesic forest had been largely established by {approx}11,250 cal yr BP, but sediment properties i… more
Date: February 8, 2005
Creator: Hillesheim, M. B.; Hodell, D. A.; Leyden, B. W.; Brenner, M.; Curtis, J. H.; Anselmetti, F. S. et al.
Partner: UNT Libraries Government Documents Department
open access

Fish Movement and Dietary History Derived from Otolith (delta)13C

Description: Habitat use and food web linkages are critical data for fish conservation and habitat restoration efforts, particularly for threatened salmonids species. Otolith microchemistry has been shown to be a powerful tool for reconstructing fish movement, but over small distances (kilometers), geology-derived differences in otolith chemistry are rare. Here, we demonstrate that otolith {sup 13}C/{sup 12}C ratio (i.e. {delta}{sup 13}C) of anadromous steelhead trout can be used to distinguish residence in… more
Date: September 8, 2005
Creator: Weber, P K; Finlay, J C; Power, M E; Phillis, C C; Ramon, C E; Eaton, G F et al.
Partner: UNT Libraries Government Documents Department
open access

Sea Water Radiocarbon Evolution in the Gulf of Alaska: 2002 Observations

Description: Oceanic uptake and transport of bomb radiocarbon as {sup 14}CO{sub 2} created by atmospheric nuclear weapons testing in the 1950s and 1960s has been a useful diagnostic to determine the carbon transfer between the ocean and atmosphere. In addition, the distribution of radiocarbon in the ocean can be used as a tracer of oceanic circulation. Results obtained from samples collected in the Gulf of Alaska in the summer of 2002 provide a direct comparison with results in the 1970s during GEOSECS and … more
Date: April 8, 2005
Creator: Guilderson, T. P.; Roark, E. B.; Quay, P. D.; Flood-Page, S. R. & Moy, C.
Partner: UNT Libraries Government Documents Department
open access

Aggregation kinetics in a model colloidal suspension

Description: The authors present molecular dynamics simulations of aggregation kinetics in a colloidal suspension modeled as a highly asymmetric binary mixture. Starting from a configuration with largely uncorrelated colloidal particles the system relaxes by coagulation-fragmentation dynamics to a structured state of low-dimensionality clusters with an exponential size distribution. The results show that short range repulsive interactions alone can give rise to so-called cluster phases. For the present mode… more
Date: August 8, 2005
Creator: Bastea, S
Partner: UNT Libraries Government Documents Department
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