Melting of bcc Transition Metals and Icosahedral Clustering (open access)

Melting of bcc Transition Metals and Icosahedral Clustering

In contrast to polyvalent metals, transition metals have low melting slopes(dT/dP) that are due to partially filled d-bands that allow for a lowering of liquid phase energy through s-d electron transfer and the formation of local structures. In the case of bcc transition metals we show the apparent discrepancy of DAC melting measurements with shock melting of Mo can be understood by reexamining the shock data for V and Ta and introducing the presence of an icosahedral short range order (ISRO) melt phase.
Date: May 26, 2006
Creator: Ross, M; Boehler, R & Japel, S
Object Type: Article
System: The UNT Digital Library
Towards an Accurate Performance Modeling of Parallel SparseFactorization (open access)

Towards an Accurate Performance Modeling of Parallel SparseFactorization

We present a performance model to analyze a parallel sparseLU factorization algorithm on modern cached-based, high-end parallelarchitectures. Our model characterizes the algorithmic behavior bytakingaccount the underlying processor speed, memory system performance, aswell as the interconnect speed. The model is validated using theSuperLU_DIST linear system solver, the sparse matrices from realapplications, and an IBM POWER3 parallel machine. Our modelingmethodology can be easily adapted to study performance of other types ofsparse factorizations, such as Cholesky or QR.
Date: May 26, 2006
Creator: Grigori, Laura & Li, Xiaoye S.
Object Type: Article
System: The UNT Digital Library
Cobra-IE Evaluation by Simulation of the NUPEC BWR Full-Size Fine-Mesh Bundle Test (BFBT) (open access)

Cobra-IE Evaluation by Simulation of the NUPEC BWR Full-Size Fine-Mesh Bundle Test (BFBT)

The COBRA-IE computer code is a thermal-hydraulic subchannel analysis program capable of simulating phenomena present in both PWRs and BWRs. As part of ongoing COBRA-IE assessment efforts, the code has been evaluated against experimental data from the NUPEC BWR Full-Size Fine-Mesh Bundle Tests (BFBT). The BFBT experiments utilized an 8 x 8 rod bundle to simulate BWR operating conditions and power profiles, providing an excellent database for investigation of the capabilities of the code. Benchmarks performed included steady-state and transient void distribution, single-phase and two-phase pressure drop, and steady-state and transient critical power measurements. COBRA-IE effectively captured the trends seen in the experimental data with acceptable prediction error. Future sensitivity studies are planned to investigate the effects of enabling and/or modifying optional code models dealing with void drift, turbulent mixing, rewetting, and CHF.
Date: April 26, 2006
Creator: Burns, C. J. and Aumiler, D. L.
Object Type: Article
System: The UNT Digital Library
DENSITY-FUNCTIONAL CALCULATIONS OF ALPHA-Pu-Ga (Al) ALLOYS (open access)

DENSITY-FUNCTIONAL CALCULATIONS OF ALPHA-Pu-Ga (Al) ALLOYS

None
Date: June 26, 2006
Creator: Landa, A; Soderlind, P & Vitos, L
Object Type: Article
System: The UNT Digital Library
B365 High Efficiency Particulate Air Filter Emergency Replacement An Example of Team Work (open access)

B365 High Efficiency Particulate Air Filter Emergency Replacement An Example of Team Work

None
Date: September 26, 2006
Creator: Coble, T; Little, C & Johnson, R
Object Type: Article
System: The UNT Digital Library
Proteomic Analysis of Calcium- and Phosphorylation-dependentCalmodulin Complexes in Mammalian Cells (open access)

Proteomic Analysis of Calcium- and Phosphorylation-dependentCalmodulin Complexes in Mammalian Cells

Protein conformational changes due to cofactor binding (e.g. metal ions, heme) and/or posttranslational modifications (e.g. phosphorylation) modulate dynamic protein complexes. Calmodulin (CaM) plays an essential role in regulating calcium (Ca{sup 2+}) signaling and homeostasis. No systematic approach on the identification of phosphorylation-dependent Ca{sup 2+}/CaM binding proteins has been published. Herein, we report a proteome-wide study of phosphorylation-dependent CaM binding proteins from mammalian cells. This method, termed 'Dynamic Phosphoprotein Complex Trapping', 'DPPC Trapping' for short, utilizes a combination of in vivo and in vitro assays. The basic strategy is to drastically shift the equilibrium towards endogenous phosphorylation of Ser, Thr, and Tyr at the global scale by inhibiting corresponding phosphatases in vivo. The phosphorylation-dependent calmodulin-binding proteins are then trapped in vitro in a Ca{sup 2+}-dependent manner by CaM-Sepharose chromatography. Finally, the isolated calmodulin-binding proteins are separated by SDS-PAGE and identified by LC/MS/MS. In parallel, the phosphorylation-dependent binding is visualized by silver staining and/or Western blotting. Using this method, we selectively identified over 120 CaM-associated proteins including many previously uncharacterized. We verified ubiquitin-protein ligase EDD1, inositol 1, 4, 5-triphosphate receptor type 1 (IP{sub 3}R1), and ATP-dependent RNA helicase DEAD box protein 3 (DDX3), as phosphorylation-dependent CaM binding proteins. To demonstrate the utilities …
Date: May 26, 2006
Creator: Jang, Deok-Jin & Wang, Daojing
Object Type: Article
System: The UNT Digital Library
Bulk Viscosity, Decaying Dark Matter, and the Cosmic Acceleration (open access)

Bulk Viscosity, Decaying Dark Matter, and the Cosmic Acceleration

The authors discuss a cosmology in which cold dark-matter particles decay into relativistic particles. They argue that such decays could lead naturally to a bulk viscosity in the cosmic fluid. for decay lifetimes comparable to the present hubble age, this bulk viscosity enters the cosmic energy equation as an effective negative pressure. They investigate whether this negative pressure is of sufficient magnitude to account for the observed cosmic acceleration. They show that a single decaying species in a {Lambda} = 0, flat, dark-matter dominated cosmology can not reproduce the observed magnitude-redshift relation from Type Ia supernovae. However, a delayed bulk viscosity, possibly due to a cascade of decaying particles may be able to account for a significant fraction of the apparent cosmic acceleration. Possible candidate nonrelativistic particles for this scenario include sterile neutrinos or gauge-mediated decaying supersymmetric particles.
Date: September 26, 2006
Creator: Wilson, J. R.; Mathews, G. & Fuller, G. M.
Object Type: Article
System: The UNT Digital Library
Commissioning of the Digital Transverse Bunch-by-Bunch Feedback System for the Tls. (open access)

Commissioning of the Digital Transverse Bunch-by-Bunch Feedback System for the Tls.

Multi-bunch instabilities degrade beam quality through increased beam emittance, energy spread and even beam loss. Feedback systems are used to suppress multi-bunch instabilities associated with the resistive wall of the beam ducts, cavity-like structures, and trapped ions. A new digital transverse bunch-by-bunch feedback system has recently been commissioned at the Taiwan Light Source, and has replaced the previous analog system. The new system has the advantages that it enlarges the tune acceptance and improves damping for transverse instability at high currents, such that top-up operation is achieved. After a coupled-bunch transverse instability was suppressed, more than 350 mA was successfully stored during preliminary commissioning. In this new system, a single feedback loop simultaneously suppresses both horizontal and vertical multi-bunch instabilities. Investigating the characteristics of the feedback loop and further improving the system performances are the next short-term goals. The feedback system employs the latest generation of field-programmable gate array (FPGA) processor to process bunch signals. Memory has been installed to capture up to 250 msec of bunch oscillation signal, considering system diagnostics suitable to support various beam physics studies.
Date: June 26, 2006
Creator: Hu, K. H.; Kuo, C. H.; Chou, P. J.; Lee, D.; Hsu, S. Y.; Chen, J. et al.
Object Type: Article
System: The UNT Digital Library
Negative Plasma Densities Raise Questions (open access)

Negative Plasma Densities Raise Questions

Nearly all the matter encountered on Earth is either a solid, liquid, or gas. Yet plasma-the fourth state of matter-comprises more than 99 percent of the visible universe. Understanding the physical characteristics of plasmas is important to many areas of scientific research, such as the development of fusion as a clean, renewable energy source. Lawrence Livermore scientists study the physics of plasmas in their pursuit to create fusion energy, because plasmas are an integral part of that process. When deuterium and tritium are heated to the extreme temperatures needed to achieve and sustain a fusion reaction (about 100 million degrees), the electrons in these light atoms become separated from the nuclei. This process of separation is called ionization, and the resulting collection of negatively charged free electrons and positively charged nuclei is known as a plasma. Although plasmas and gases have many similar properties, plasmas differ from gases in that they are good conductors of electricity and can generate magnetic fields. For the past decade, x-ray laser interferometry has been used in the laboratory for measuring a plasma's index of refraction to determine plasma density. (The index of refraction for a given material is defined as the wavelength of light …
Date: January 26, 2006
Creator: Hazi, A.
Object Type: Report
System: The UNT Digital Library
Detection of Ultra High Energy Neutrinos via Coherent Radio Emission (open access)

Detection of Ultra High Energy Neutrinos via Coherent Radio Emission

None
Date: May 26, 2006
Creator: Varner, G.; Gorham, P. W.; Kowalski, R. J.; Learned, J. G.; Link, J. T.; Matsuno, S. et al.
Object Type: Article
System: The UNT Digital Library
Evaluation of an Unsuccessful Brook Trout Electrofishing Removal Project in a Small Rocky Mountain Stream. (open access)

Evaluation of an Unsuccessful Brook Trout Electrofishing Removal Project in a Small Rocky Mountain Stream.

In the western United States, exotic brook trout Salvelinus fontinalis frequently have a deleterious effect on native salmonids, and biologists often attempt to remove brook trout from streams by means of electrofishing. Although the success of such projects typically is low, few studies have assessed the underlying mechanisms of failure, especially in terms of compensatory responses. A multiagency watershed advisory group (WAG) conducted a 3-year removal project to reduce brook trout and enhance native salmonids in 7.8 km of a southwestern Idaho stream. We evaluated the costs and success of their project in suppressing brook trout and looked for brook trout compensatory responses, such as decreased natural mortality, increased growth, increased fecundity at length, and earlier maturation. The total number of brook trout removed was 1,401 in 1998, 1,241 in 1999, and 890 in 2000; removal constituted an estimated 88% of the total number of brook trout in the stream in 1999 and 79% in 2000. Although abundance of age-1 and older brook trout declined slightly during and after the removals, abundance of age-0 brook trout increased 789% in the entire stream 2 years after the removals ceased. Total annual survival rate for age-2 and older brook trout did not …
Date: January 26, 2006
Creator: Meyer, Kevin A.; Lamansky, Jr., James A. & Schill, Daniel J.
Object Type: Article
System: The UNT Digital Library
Sampling and Analysis Plan - Waste Treatment Plant Seismic Boreholes Project (open access)

Sampling and Analysis Plan - Waste Treatment Plant Seismic Boreholes Project

This sampling and analysis plan (SAP) describes planned data collection activities for four entry boreholes through the sediment overlying the basalt, up to three new deep rotary boreholes through the basalt and sedimentary interbeds, and one corehole through the basalt and sedimentary interbeds at the Waste Treatment Plant (WTP) site. The SAP will be used in concert with the quality assurance plan for the project to guide the procedure development and data collection activities needed to support borehole drilling, geophysical measurements, and sampling. This SAP identifies the American Society of Testing Materials standards, Hanford Site procedures, and other guidance to be followed for data collection activities.
Date: May 26, 2006
Creator: Reidel, Steve P.
Object Type: Report
System: The UNT Digital Library
Basin Analysis and Petroleum System Characterization and Modeling, Interior Salt Basins, Central and Eastern Gulf of Mexico (open access)

Basin Analysis and Petroleum System Characterization and Modeling, Interior Salt Basins, Central and Eastern Gulf of Mexico

The principal research effort for Phase 1 (Concept Development) of the project has been data compilation; determination of the tectonic, depositional, burial, and thermal maturation histories of the North Louisiana Salt Basin; basin modeling (geohistory, thermal maturation, hydrocarbon expulsion); petroleum system identification; comparative basin evaluation; and resource assessment. Existing information on the North Louisiana Salt Basin has been evaluated, an electronic database has been developed, and regional cross sections have been prepared. Structure, isopach and formation lithology maps have been constructed, and burial history, thermal maturation history, and hydrocarbon expulsion profiles have been prepared. Seismic data, cross sections, subsurface maps and burial history, thermal maturation history, and hydrocarbon expulsion profiles have been used in evaluating the tectonic, depositional, burial and thermal maturation histories of the basin. Oil and gas reservoirs have been found to be associated with salt-supported anticlinal and domal features (salt pillows, turtle structures and piercement domes); with normal faulting associated with the northern basin margin and listric down-to-the-basin faults (state-line fault complex) and faulted salt features; and with combination structural and stratigraphic features (Sabine and Monroe Uplifts) and monoclinal features with lithologic variations. Petroleum reservoirs include Upper Jurassic and Cretaceous fluvial-deltaic sandstone facies; shoreline, marine bar and …
Date: May 26, 2006
Creator: Mancini, Ernest A.; Aharon, Paul; Goddard, Donald A. & Barnaby, Roger
Object Type: Report
System: The UNT Digital Library
Measurement of the Hadronic Form Factors in Ds to phi e nu Decays (open access)

Measurement of the Hadronic Form Factors in Ds to phi e nu Decays

Based on the measured four-dimensional rate for D{sub s}{sup +} {yields} {phi}e{sup +}{nu}{sub e} decays, they have determined the ratios of the three hadronic form factors, {tau}{sub V} = V(0)/A{sub 1}(0) = 1.636 {+-} 0.067 {+-} 0.038 and {tau}{sub 2} = A{sub 2}(0)/A{sub 1}(0) = 0.705 {+-} 0.056 {+-} 0.029, using a simple pole ansatz for the q{sup 2} dependence, with fixed values of the pole masses for both the vector and axial form factors. By a separate fit to the same data, they have also extracted the pole mass for the axial form factors, m{sub A}: {tau}{sub V} = V(0)/A{sub 1}(0) = 1.633 {+-} 0.081 {+-} 0.068, {tau}{sub 2} = A{sub 2}(0)/A{sub 1}(0) = 0.711 {+-} 0.111 {+-} 0.096 and m{sub A} = (2.53{sub -0.35}{sup +0.54} {+-} 0.54)GeV/c{sup 2}.
Date: September 26, 2006
Creator: Serrano, J.
Object Type: Article
System: The UNT Digital Library
Time-dependent CP-violation Parameters in B0 to eta' K0 Decay (open access)

Time-dependent CP-violation Parameters in B0 to eta' K0 Decay

The authors present measurements of time-dependent CP-violation asymmetries for the decays B{sup 0} {yields} {eta}'K{sup 0}. The data sample corresponds to 347 million B{bar B} pairs produced by e{sup +}e{sup -} annihilation at the {Upsilon}(4S) resonance in the PEP-II collider, and collected with the BABAR detector. The preliminary results are S = 0.55 {+-} 0.11 {+-} 0.02, and C = -0.015 {+-} 0.07 {+-} 0.03, where the first error quoted is statistical, the second systematic.
Date: September 26, 2006
Creator: Ulmer, K
Object Type: Article
System: The UNT Digital Library
Esimation of field-scale thermal conductivities of unsaturatedrocks from in-situ temperature data (open access)

Esimation of field-scale thermal conductivities of unsaturatedrocks from in-situ temperature data

A general approach is presented here which allows estimationof field-scale thermal properties of unsaturated rock using temperaturedata collected from in situ heater tests. The approach developed here isused to determine the thermal conductivities of the unsaturated host rockof the Drift Scale Test (DST) at Yucca Mountain, Nevada. The DST wasdesigned to obtain thermal, hydrological, mechanical, and chemical (THMC)data in the unsaturated fractured rock of Yucca Mountain. Sophisticatednumerical models have been developed to analyze these THMC data. However,though the objective of those models was to analyze "field-scale" (of theorder of tens-of-meters) THMC data, thermal conductivities measured from"laboratory-scale" core samples have been used as input parameters.While, in the absence of a better alternative, using laboratory-scalethermal conductivity values in field-scale models can be justified, suchapplications introduce uncertainties in the outcome of the models. Thetemperature data collected from the DST provides a unique opportunity toresolve some of these uncertainties. These temperature data can be usedto estimate the thermal conductivity of the DST host rock and, given thelarge volume of rock affected by heating at the DST, such an estimatewill be a more reliable effective thermal conductivity value for fieldscale application. In this paper, thus, temperature data from the DST areused to develop an estimate …
Date: June 26, 2006
Creator: Mukhopadhyay, Sumit; Tsang, Yvonne W. & Birkholzer, Jens T.
Object Type: Article
System: The UNT Digital Library
Seismicity and Improved Velocity Structure in Kuwait (open access)

Seismicity and Improved Velocity Structure in Kuwait

The Kuwait National Seismic Network (KNSN) began operation in 1997 and consists of nine three-component stations (eight short-period and one broadband) and is operated by the Kuwait Institute for Scientific Research. Although the region is largely believed to be aseismic, considerable local seismicity is recorded by KNSN. Seismic events in Kuwait are clustered in two main groups, one in the south and another in the north. The KNSN station distribution is able to capture the southern cluster within the footprint of the network but the northern cluster is poorly covered. Events tend to occur at depths ranging from the free surface to about 20 km. Events in the northern cluster tend to be deeper than those in south, however this might be an artifact of the station coverage. We analyzed KNSN recordings of nearly 200 local events to improve understanding of seismic events and crustal structure in Kuwait, performing several analyses with increasing complexity. First, we obtained an optimized one-dimensional (1D) velocity model for the entire region using the reported KNSN arrival times and routine locations. The resulting model is consistent with a recently obtained model from the joint inversion of receiver functions and surface wave group velocities. Crustal structure …
Date: January 26, 2006
Creator: Gok, R. M.; Rodgers, A. J. & Al-Enezi, A.
Object Type: Report
System: The UNT Digital Library
Synopsis of Cathode #4 Activation (open access)

Synopsis of Cathode #4 Activation

The purpose of this report is to describe the activation of the fourth cathode installed in the DARHT-II Injector. Appendices have been used so that an extensive amount of data could be included without danger of obscuring important information contained in the body of the report. The cathode was a 612 M type cathode purchased from Spectra-Mat. Section II describes the handling and installation of the cathode. Section III is a narrative of the activation based on information located in the Control Room Log Book supplemented with time plots of pertinent operating parameters. Activation of the cathode was performed in accordance with the procedure listed in Appendix A. The following sections provide more details on the total pressure and constituent partial pressures in the vacuum vessel, cathode heater power/filament current, and cathode temperature.
Date: May 26, 2006
Creator: Kwan, Joe; Ekdahl, C.; Harrison, J.; Kwan, J.; Leitner, M.; McCruistian, T. et al.
Object Type: Report
System: The UNT Digital Library
Dynamical Expansion of HII Regions From Ultracompact to Compact Sizes in Turbulent, Self-Gravitating Molecular Clouds (open access)

Dynamical Expansion of HII Regions From Ultracompact to Compact Sizes in Turbulent, Self-Gravitating Molecular Clouds

None
Date: May 26, 2006
Creator: Low, Mordecai-Mark Mac; Toraskar, Jayashree; Oishi, Jeffrey S. & Abel, Tom
Object Type: Report
System: The UNT Digital Library
Resource Assessment of the In-Place and Potentially Recoverable Deep Natural Gas Resource of the Onshore Interior Salt Basins, North Central and Northeastern Gulf of Mexico Semiannual Progress Report: Year 3 (open access)

Resource Assessment of the In-Place and Potentially Recoverable Deep Natural Gas Resource of the Onshore Interior Salt Basins, North Central and Northeastern Gulf of Mexico Semiannual Progress Report: Year 3

The principal research effort for the first half of Year 3 of the project has been resource assessment. Emphasis has been on estimating the total volume of hydrocarbons generated and the potential amount of this resource that is classified as deep (>15,000 ft) gas in the North Louisiana Salt Basin, the Mississippi Interior Salt Basin, the Manila Subbasin and the Conecuh Subbasin. The amount of this resource that has been expelled, migrated and entrapped is also the focus of the first half of Year 3 of this study.
Date: April 26, 2006
Creator: Mancini, Ernest A.; Aharon, Paul; Goddard, Donald A. & Barnaby, Roger
Object Type: Report
System: The UNT Digital Library
Photon Production through Multi-step Processes Important in Nuclear Fluorescence Experiments (open access)

Photon Production through Multi-step Processes Important in Nuclear Fluorescence Experiments

The authors present calculations describing the production of photons through multi-step processes occurring when a beam of gamma rays interacts with a macroscopic material. These processes involve the creation of energetic electrons through Compton scattering, photo-absorption and pair production, the subsequent scattering of these electrons, and the creation of energetic photons occurring as these electrons are slowed through Bremsstrahlung emission. Unlike single Compton collisions, during which an energetic photon that is scattered through a large angle loses most of its energy, these multi-step processes result in a sizable flux of energetic photons traveling at large angles relative to an incident photon beam. These multi-step processes are also a key background in experiments that measure nuclear resonance fluorescence by shining photons on a thin foil and observing the spectrum of back-scattered photons. Effective cross sections describing the production of backscattered photons are presented in a tabular form that allows simple estimates of backgrounds expected in a variety of experiments. Incident photons with energies between 0.5 MeV and 8 MeV are considered. These calculations of effective cross sections may be useful for those designing NRF experiments or systems that detect specific isotopes in well-shielded environments through observation of resonance fluorescence.
Date: October 26, 2006
Creator: Hagmann, C & Pruet, J
Object Type: Article
System: The UNT Digital Library
The Role of Nuclear Motion in the Photo-Double Ionization ofMolecular Hydrogen (open access)

The Role of Nuclear Motion in the Photo-Double Ionization ofMolecular Hydrogen

We examine the origin of recently observed variations with internuclear distance (R) of the fully differential cross sections for double ionization of aligned H2 by absorption of a single photon. Using the results of fully converged numerical solutions of the Schroedinger equation, we show that these variations arise primarily from pronounced differences in the R-dependence of the parallel and perpendicular components of the ionization amplitude. We also predict that R-dependences should be readily observable in the asymmetry parameter for photo-double ionization, even in experimental measurements that are not differential in the energy sharings between ejected photo-electrons.
Date: October 26, 2006
Creator: Horner, Daniel A.; Vanroose, Wim; Rescigno, Thomas N.; Martin,Fernando & McCurdy, C. William
Object Type: Article
System: The UNT Digital Library
Remaining Sites Verification Package for the 116-F-8, 1904-F Outfall Structure and the 100-F-42, 1904-F Spillway, Waste Site Reclassification Form 2006-045 (open access)

Remaining Sites Verification Package for the 116-F-8, 1904-F Outfall Structure and the 100-F-42, 1904-F Spillway, Waste Site Reclassification Form 2006-045

The 100-F-42 waste site is the portion of the former emergency overflow spillway for the 1904-F Outfall Structure formerly existing above the ordinary high water mark of the Columbia River. The spillway consisted of a concrete flume designed to discharge effluent from the 107-F Retention Basin in the event that flows could not be completely discharged via the river outfall pipelines. The results of verification sampling show that residual contaminant concentrations do not preclude any future uses and allow for unrestricted use of shallow zone soils. The results also demonstrate that residual contaminant concentrations are protective of groundwater and the Columbia River.
Date: September 26, 2006
Creator: Dittmer, L. M.
Object Type: Report
System: The UNT Digital Library
Induced seismicity associated with enhanced geothermal system (open access)

Induced seismicity associated with enhanced geothermal system

Enhanced Geothermal Systems (EGS) offer the potential to significantly add to the world energy inventory. As with any development of new technology, some aspects of the technology has been accepted by the general public, but some have not yet been accepted and await further clarification before such acceptance is possible. One of the issues associated with EGS is the role of microseismicity during the creation of the underground reservoir and the subsequent extraction of the energy. The primary objectives of this white paper are to present an up-to-date review of the state of knowledge about induced seismicity during the creation and operation of enhanced geothermal systems, and to point out the gaps in knowledge that if addressed will allow an improved understanding of the mechanisms generating the events as well as serve as a basis to develop successful protocols for monitoring and addressing community issues associated with such induced seismicity. The information was collected though literature searches as well as convening three workshops to gather information from a wide audience. Although microseismicity has been associated with the development of production and injection operations in a variety of geothermal regions, there have been no or few adverse physical effects on the …
Date: September 26, 2006
Creator: Majer, Ernest; Majer, Ernest L.; Baria, Roy; Stark, Mitch; Oates, Stephen; Bommer, Julian et al.
Object Type: Article
System: The UNT Digital Library