Numerical Tests and Properties of Waves in Radiating Fluids (open access)

Numerical Tests and Properties of Waves in Radiating Fluids

We discuss the properties of an analytical solution for waves in radiating fluids, with a view towards its implementation as a quantitative test of radiation hydrodynamics codes. A homogeneous radiating fluid in local thermodynamic equilibrium is periodically driven at the boundary of a one-dimensional domain, and the solution describes the propagation of the waves thus excited. Two modes are excited for a given driving frequency, generally referred to as a radiative acoustic wave and a radiative diffusion wave. While the analytical solution is well known, several features are highlighted here that require care during its numerical implementation. We compare the solution in a wide range of parameter space to a numerical integration with a Lagrangian radiation hydrodynamics code. Our most significant observation is that flux-limited diffusion does not preserve causality for waves on a homogeneous background.
Date: September 3, 2009
Creator: Johnson, B M & Klein, R I
Object Type: Article
System: The UNT Digital Library
Final Report: Transport and its regulation in Marine Microorganisms: A Genomic Based Approach (open access)

Final Report: Transport and its regulation in Marine Microorganisms: A Genomic Based Approach

This grant funded the analysis and annotation of the genomes of Synechococcus and Ostreococcus, major marine primary producers. Particular attention was paid to the analysis of transporters using state of the art bioinformatics analyses. During the analysis of the Synechococcus genome, some of the components of the unique bacterial swimming apparatus of one species of Synechococcus (Clade III, strain WH8102) were determined and these included transporters, novel giant proteins and glycosyltransferases. This grant funded the analysis of gene expression in Synechococcus using whole genome microarrays. These analyses revealed the strategies by which marine cyanobacteria respond to environmental conditions such as the absence of phosphorus, a common limiting nutrient, and the interaction of Synechococcus with other microbes. These analyses will help develop models of gene regulation in cyanobacteria and thus help predict their responses to changes in environmental conditions.
Date: September 3, 2009
Creator: Palenik, Brian; Brahamsha, Bianca & Paulsen, Ian
Object Type: Report
System: The UNT Digital Library
Groundwater and Leachate Monitoring and Sampling at ERDF, CY 2008 (open access)

Groundwater and Leachate Monitoring and Sampling at ERDF, CY 2008

The purpose of this annual monitoring report is to evaluate the conditions of and identify trends for groundwater beneath the ERDF, to report leachate results in fulfillment of the requirements specified in the ERDF ROD and the ERDF Amended ROD.
Date: September 3, 2009
Creator: Weiss, R. L. & Woolery, D. W.
Object Type: Report
System: The UNT Digital Library
SYNTHESIS OF NON-RADIOACTIVE SLURRIES TO SIMULATE THE PROCESSING BEHAVIOR OF PARTICLES IN RADIOACTIVE WASTE SLURRIES 626-G (open access)

SYNTHESIS OF NON-RADIOACTIVE SLURRIES TO SIMULATE THE PROCESSING BEHAVIOR OF PARTICLES IN RADIOACTIVE WASTE SLURRIES 626-G

Process development using non-radioactive analogs to high-level radioactive waste slurries is an established cost effective alternative to working with actual samples of the real waste. Current simulated waste slurries, however, do not capture all of the physical behavior of real waste. New methods of preparing simulants are under investigation along with mechanisms for altering certain properties of finished simulants. These methods have achieved several notable successes recently in the areas of rheology and foaminess. Particle size is also being manipulated more effectively than in the past, though not independently of the rheological properties. The interaction between rheology and foaminess has exhibited counter-intuitive behavior with more viscous slurries being less foamy even though drainage of liquid from the foam lamellae should be inhibited by higher viscosities.
Date: September 3, 2009
Creator: Koopman, D.; Lambert, D.; Eibling, R.; Newell, J. & Stone, M.
Object Type: Article
System: The UNT Digital Library
LIFE Chamber Chemical Equilibrium Simulations with Additive Hydrogen, Oxygen, and Nitrogen (open access)

LIFE Chamber Chemical Equilibrium Simulations with Additive Hydrogen, Oxygen, and Nitrogen

In order to enable continuous operation of a Laser Inertial confinement Fusion Energy (LIFE) engine, the material (fill-gas and debris) in the fusion chamber must be carefully managed. The chamber chemical equilibrium compositions for post-shot mixtures are evaluated to determine what compounds will be formed at temperatures 300-5000K. It is desired to know if carbon and or lead will deposit on the walls of the chamber, and if so: at what temperature, and what elements can be added to prevent this from happening. The simulation was conducted using the chemical equilibrium solver Cantera with a Matlab front-end. Solutions were obtained by running equilibrations at constant temperature and constant specific volume over the specified range of temperatures. It was found that if nothing is done, carbon will deposit on the walls once it cools to below 2138K, and lead below 838K. Three solutions to capture the carbon were found: adding pure oxygen, hydrogen/nitrogen combo, and adding pure nitrogen. The best of these was the addition of oxygen which would readily form CO at around 4000K. To determine the temperature at which carbon would deposit on the walls, temperature solutions to evaporation rate equations needed to be found. To determine how much …
Date: September 3, 2009
Creator: DeMuth, J A & Simon, A J
Object Type: Report
System: The UNT Digital Library
Integrated Genomic Analysis Identifies Clinically Relevant Subtypes of Glioblastoma Characterized by Abnormalities in PDGFRA, IDH1, EGFR, and NF1 (open access)

Integrated Genomic Analysis Identifies Clinically Relevant Subtypes of Glioblastoma Characterized by Abnormalities in PDGFRA, IDH1, EGFR, and NF1

The Cancer Genome Atlas Network recently cataloged recurrent genomic abnormalities in glioblastoma multiforme (GBM). We describe a robust gene expression-based molecular classification of GBM into Proneural, Neural, Classical, and Mesenchymal subtypes and integrate multidimensional genomic data to establish patterns of somatic mutations and DNA copy number. Aberrations and gene expression of EGFR, NF1, and PDGFRA/IDH1 each define the Classical, Mesenchymal, and Proneural subtypes, respectively. Gene signatures of normal brain cell types show a strong relationship between subtypes and different neural lineages. Additionally, response to aggressive therapy differs by subtype, with the greatest benefit in the Classical subtype and no benefit in the Proneural subtype. We provide a framework that unifies transcriptomic and genomic dimensions for GBM molecular stratification with important implications for future studies.
Date: September 3, 2009
Creator: Verhaak, Roel GW; Hoadley, Katherine A; Purdom, Elizabeth; Wang, Victoria; Qi, Yuan; Wilkerson, Matthew D et al.
Object Type: Article
System: The UNT Digital Library
Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma (open access)

Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma

Neutralization and focusing of intense charged particle beam pulses by a background plasma forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal …
Date: September 3, 2009
Creator: Kaganovich, I. D.; Davidson, R. C.; Dorf, M. A.; Startsev, E. A.; Sefkow, A. B.; Friedman, A. F. et al.
Object Type: Article
System: The UNT Digital Library