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High Resolution Simulations of Ignition Capsule Designs for the National Ignition Facility (open access)

High Resolution Simulations of Ignition Capsule Designs for the National Ignition Facility

Ignition capsule designs for the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 443, 2841 (2004)] have continued to evolve in light of improved physical data inputs, improving simulation techniques, and - most recently - experimental data from a growing number of NIF sub-ignition experiments. This paper summarizes a number of recent changes to the cryogenic capsule design and some of our latest techniques in simulating its performance. Specifically, recent experimental results indicated harder x-ray drive spectra in NIF hohlraums than were predicted and used in previous capsule optimization studies. To accommodate this harder drive spectrum, a series of high-resolution 2-D simulations, resolving Legendre mode numbers as high as two thousand, were run and the germanium dopant concentration and ablator shell thicknesses re-optimized accordingly. Simultaneously, the possibility of cooperative or nonlinear interaction between neighboring ablator surface defects has motivated a series of fully 3-D simulations run with the massively parallel HYDRA code. These last simulations include perturbations seeded on all capsule interfaces and can use actual measured shell surfaces as initial conditions. 3-D simulations resolving Legendre modes up to two hundred on large capsule sectors have run through ignition and burn, and …
Date: February 17, 2011
Creator: Clark, D. S.; Haan, S. W.; Cook, A. W.; Edwards, M. J.; Hammel, B. A.; Koning, J. M. et al.
System: The UNT Digital Library
Pressure-induced changes in the electronic structure of americium metal (open access)

Pressure-induced changes in the electronic structure of americium metal

We have conducted electronic-structure calculations for Am metal under pressure to investigate the behavior of the 5f-electron states. Density-functional theory (DFT) does not reproduce the experimental photoemission spectra for the ground-state phase where the 5f electrons are localized, but the theory is expected to be correct when 5f delocalization occurs under pressure. The DFT prediction is that peak structures of the 5f valence band will merge closer to the Fermi level during compression indicating presence of itinerant 5f electrons. Existence of such 5f bands is argued to be a prerequisite for the phase transitions, particularly to the primitive orthorhombic AmIV phase, but does not agree with modern dynamical-mean-field theory (DMFT) results. Our DFT model further suggests insignificant changes of the 5f valence under pressure in agreement with recent resonant x-ray emission spectroscopy, but in contradiction to the DMFT predictions. The influence of pressure on the 5f valency in the actinides is discussed and is shown to depend in a non-trivial fashion on 5f band position and occupation relative to the spd valence bands.
Date: February 25, 2011
Creator: Soderlind, P; Moore, K T; Landa, A & Bradley, J A
System: The UNT Digital Library
Reciprocal Suffering: Caregiver Concerns During Hospice Care (open access)

Reciprocal Suffering: Caregiver Concerns During Hospice Care

Article on caregiver concerns during hospice care and reciprocal suffering.
Date: February 2011
Creator: Wittenberg-Lyles, Elaine; Demiris, George; Oliver, Debra Parker & Burt, Stephanie
System: The UNT Digital Library
Visualization of Lipid Droplet Composition by Direct Organelle Mass Spectrometry (open access)

Visualization of Lipid Droplet Composition by Direct Organelle Mass Spectrometry

Article reporting an approach that combines the visualization of individual lipid droplets (LDs), microphase extraction of lipid components from droplets, and the direct identification of lipid composition by nanospray mass spectrometry, even to the level of a single LD. The triacylglycerol (TAG) composition of LDs from several plant sources (mature cotton (Gossypium hirsutum) embryos, roots of cotton seedlings, and Arabidopsis thaliana seeds and leaves) were examined by direct organelle mass spectrometry and revealed the heterogeneity of LDs derived from different plant tissue sources.
Date: February 4, 2011
Creator: Horn, Patrick J.; Ledbetter, Nicole R.; James, Christopher N.; Hoffman, William D.; Case, Charlene R.; Verbeck, Guido F. et al.
System: The UNT Digital Library
Photoelectron Spectroscopic Study of the Oxyallyl Diradical (open access)

Photoelectron Spectroscopic Study of the Oxyallyl Diradical

Article on a photoelectron spectroscopic study of the oxyallyl diradical.
Date: February 16, 2011
Creator: Ichino, Takatoshi; Villano, Stephanie M.; Gianola, Adam J.; Goebbert, Daniel J.; Velarde, Luis; Sanov, Andrei et al.
System: The UNT Digital Library
3,5-Bis(4-chlorobenzylidene)-1-methyl-piperidin-4-one (open access)

3,5-Bis(4-chlorobenzylidene)-1-methyl-piperidin-4-one

In the title molecule, C₂₀H₁₇Cl₂NO, the central heterocyclic ring adopts a flattened boat conformation.
Date: February 23, 2011
Creator: Nesterov, Volodymyr V.; Sarkisov, Sergey S.; Shulaev, Vladimir & Nesterov, Vladimir N.
System: The UNT Digital Library
A Nitsche Embedded Mesh Method (open access)

A Nitsche Embedded Mesh Method

None
Date: February 22, 2011
Creator: Sanders, J. D.; Laursen, T. A. & Puso, M. A.
System: The UNT Digital Library
Ab Initio Many-Body Calculations of Deuteron-4He Scattering And 6Li States (open access)

Ab Initio Many-Body Calculations of Deuteron-4He Scattering And 6Li States

None
Date: February 8, 2011
Creator: Quaglioni, S & Navratil, P
System: The UNT Digital Library
A computational study of x-ray emission from high-Z x-ray sources on the National Ignition Facility laser (open access)

A computational study of x-ray emission from high-Z x-ray sources on the National Ignition Facility laser

None
Date: February 7, 2011
Creator: Colvin, J. D.; Fournier, K. B.; Kane, J.; Langer, S.; May, M. J. & Scott, H. A.
System: The UNT Digital Library
Archaeological Protein Residues: New Data for Conservation Science (open access)

Archaeological Protein Residues: New Data for Conservation Science

This article identifies several cases where archaeological protein residues may be of benefit, justifies the use of protein residues in particular, and discusses areas for improvement.
Date: February 17, 2011
Creator: Barker, Andrew
System: The UNT Digital Library
Photon Beamlines and Diagnostics at LCLS (open access)

Photon Beamlines and Diagnostics at LCLS

The Linac Coherent Light Source (LCLS) is the first hard-x-ray free electron laser in operation. The turn-on of LCLS was rapid and operation has been reliable. Performance has exceeded the design parameters in several areas. The photon energy output covers a range from 480 eV to over 9 keV; the pulse energy is typically 2-3 mJ, with a maximum of 4 mJ at 2 keV. Electron pulse lengths can be varied from 500 fs to shorter than 10 fs. A low-charge option at 20 pC is being explored, which delivers pulses shorter than 10 fs with a reduced pulse energy, typically around 0.2 mJ. On-demand, single-shot and multi-shot modes up to 60 Hz (planned is 120 Hz) can be made available. The photon diagnostics built for LCLS have been commissioned and provide measurements of various properties of the FEL beam, such as pulse energy, beam size and position, wavelength, and allows for intensity attenuation over the entire wavelength range. The two soft x-ray instruments, the Atomic Molecular and Optics (AMO) and Soft X-ray Material Science (SXR) stations, are fully operational and completed their second user run in mid September 2010. The third user run is scheduled from October to December …
Date: February 7, 2011
Creator: Moeller, S.; Arthur, J.; Brachmann, A.; Coffee, R.; Decker, F.-J.; Edstrom, S. et al.
System: The UNT Digital Library
Consistent Approximation of Local Flow Behavior for 2D Vector Fields using Edge Maps (open access)

Consistent Approximation of Local Flow Behavior for 2D Vector Fields using Edge Maps

None
Date: February 1, 2011
Creator: Jadhav, Shreeraj; Bhatia, Harsh; Bremer, Peer-Timo; Levine, Joshua A.; Nonato, Luis Gustavo & Pascucci, Valerio
System: The UNT Digital Library
The Ecoresponsive Genome of Daphnia pulex (open access)

The Ecoresponsive Genome of Daphnia pulex

This article discusses the ecoresponsive genome of Daphnia pulex.
Date: February 4, 2011
Creator: Colbourne, John K.; Pfrender, Michael E.; Gilbert, Donald; Thomas, W. Kelley; Tucker, Abraham; Oakley, Todd H. et al.
System: The UNT Digital Library
Single actomyosin motor interactions in skeletal muscle (open access)

Single actomyosin motor interactions in skeletal muscle

This article presents a study of intramuscular motion during contraction of skeletal muscle myofibrils.
Date: February 21, 2011
Creator: Földes-Papp, Zeno; Liao, Jeff Shih-Chu; Barbieri, Ben; Grycznski, Karol G.; Luchowski, Rafal; Gryczynski, Ignacy et al.
System: The UNT Digital Library
Experimental and Computational Studies of the Isomerization Reactions of Bidentate Phosphine Ligands in Triosmium Clusters: Kinetics of the Rearrangements from Bridged to Chelated Isomers and X-ray Structures of the Clusters Os3 (CO)10 (dppbz), 1,1-Os3 (CO)10 (dppbzF4), HOs3 (CO)9 [μ -1,2-PhP (C6H4-ɳ1) C6H4PPh2], and HOs3 (CO)9- [μ-1,2-PhP (C6H4-ɳ 1) C6F4PPh2] (open access)

Experimental and Computational Studies of the Isomerization Reactions of Bidentate Phosphine Ligands in Triosmium Clusters: Kinetics of the Rearrangements from Bridged to Chelated Isomers and X-ray Structures of the Clusters Os3 (CO)10 (dppbz), 1,1-Os3 (CO)10 (dppbzF4), HOs3 (CO)9 [μ -1,2-PhP (C6H4-ɳ1) C6H4PPh2], and HOs3 (CO)9- [μ-1,2-PhP (C6H4-ɳ 1) C6F4PPh2]

Article on experimental and computational studies of the isomerization reactions of bidentate phosphine ligands in triosmium clusters.
Date: February 22, 2011
Creator: Zhang, Xue; Kandala, Srikanth; Yang, Li; Watson, William H.; Wang, Xiaoping; Hrovat, David A. et al.
System: The UNT Digital Library