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2004 Rock Deformation Gordon Conference - August 8-12, 2004 (open access)

2004 Rock Deformation Gordon Conference - August 8-12, 2004

Rock Deformation Gordon Conference Agenda and Final Report.
Date: August 8, 2004
Creator: Kronenberg, A. K.
System: The UNT Digital Library
21st Century Steam for Asteroid Mitigation (open access)

21st Century Steam for Asteroid Mitigation

The systematic requirements to divert an object on an earth-impacting course are developed relating the minimum velocity perturbation (both magnitude and direction) to the time available before impact. This, coupled with the accuracy to which orbits can be determined, restricts the time available for any mitigation technology to operate. Because nuclear energy densities are nearly a million times higher than those possible with chemical bonds, it is the most mass efficient means for storing delivering energy with today's technology. The question is how to most effectively apply that energy. This paper will examine the simple case of shattering the body, as well as a more controlled approach in which one or more small velocity increments divert a body. The optimal approach depends on the detailed circumstances, but in either case, already developed technology permits a successful diversion with a few years to decades of notice. The success of nuclear options on relatively short timescales permits consideration of other technologies that while not so well developed might be sufficiently improved to divert small (100 meter) bodies.
Date: March 10, 2004
Creator: Dearborn, D S
System: The UNT Digital Library
2nd International Conference on Pathways, Networks, and Systems: Theory and Experiments (open access)

2nd International Conference on Pathways, Networks, and Systems: Theory and Experiments

With the availability of whole genome sequences, research attention shifts from gene sequences and genome content to protein functions and systems biology. Genes comprise a major component of the ''parts list'' that is required for building and maintaining of living organisms. Genome DNA sequences reveal the genetic inventory for a rapidly increasing number of species. Defining and interpreting the instruction manual for protein functions, individually and collectively, is the emerging challenge. Defining protein functions is a complex problem because each gene typically encodes several distinct proteins. As a result, the protein inventory includes as many as 100,000 distinct proteins. Protein functions can vary with developmental stage, anatomical location, and environmental context. Like the problem of sequencing the human genome, the multidimensional nature of protein functions in time, space and context constitutes one of the ''big'' problems in biomedical research. Resolving this problem is key to revolutionizing health care where a deep understanding of complex biological systems will lead to more powerful and specific ways to treat, and perhaps, even prevent birth defects and adult diseases. The meeting addressed the above issues.
Date: October 1, 2004
Creator: Aegean Conferences
System: The UNT Digital Library
A 3D Frictional Segment-to-Segment Contact Method for Large Deformations and Quadratic Elements (open access)

A 3D Frictional Segment-to-Segment Contact Method for Large Deformations and Quadratic Elements

Node-on-segment contact is the most common form of contact used today but has many deficiencies ranging from potential locking to non-smooth behavior with large sliding. Furthermore, node-on-segment approaches are not at all applicable to higher order discretizations (e.g. quadratic elements). In a previous work, [3, 4] we developed a segment-to-segment contact approach for eight node hexahedral elements based on the mortar method that was applicable to large deformation mechanics. The approach proved extremely robust since it eliminated the over-constraint that caused 'locking' and provided smooth force variations in large sliding. Here, we extend this previous approach to treat frictional contact problems. In addition, the method is extended to 3D quadratic tetrahedrals and hexahedrals. The proposed approach is then applied to several challenging frictional contact problems that demonstrate its effectiveness.
Date: April 1, 2004
Creator: Puso, M; Laursen, T & Solberg, J
System: The UNT Digital Library
48Ti(n,xnypz ag) reactions for neutron energies up to 250 MeV (open access)

48Ti(n,xnypz ag) reactions for neutron energies up to 250 MeV

Cross section measurements were made of prompt {gamma}-ray production as a function of incident neutron energy on a {sup 48}Ti sample. Partial {gamma}-ray cross sections for transitions in {sup 45--48}Ti, {sup 44--48}Sc, {sup 42--45}Ca, {sup 41--44}K, and {sup 41--42}Ar have been determined. Energetic neutrons were delivered by the Los Alamos National Laboratory spallation neutron source located at the LANSCE/WNR facility. The prompt-reaction {gamma} rays were detected with the large-scale Compton-suppressed germanium array for neutron induced excitations (GEANIE). Neutron energies were determined by the time-of-flight technique. The {gamma}-ray excitation functions were converted to partial {gamma}-ray cross sections taking into account the dead-time correction, target thickness, detector efficiency and neutron flux (monitored with an in-line fission chamber). The data will be presented for neutron energies between 1 to 250 MeV. These results are compared with model calculations which include compound nuclear and pre-equilibrium emission.
Date: October 11, 2004
Creator: Dashdorj, D.; Garrett, P. E.; Becker, J. A.; Bernstein, L. A.; Cooper, J. R.; Devlin, M. et al.
System: The UNT Digital Library
5th Biotechnological Investigations Ocean Margins Program (open access)

5th Biotechnological Investigations Ocean Margins Program

BI-OMP supports DOE's mission in Climate Change Research. The program provides the fundamental understanding of the linkages between carbon and nitrogen cycles in ocean margins. Researchers are providing a mechanistic understanding of these cycles, using the tools of modern molecular biology. The models that will allow policy makers to determine safe levels of greenhouse gases for the Earth System.
Date: January 8, 2004
Creator: Massol, Arturo & Buxeda, Rosa
System: The UNT Digital Library
6th International Microbeam Workshop (open access)

6th International Microbeam Workshop

The extended abstracts which are submitted here present a summary of the proceedings of the 6th International Workshop/12th LH Gray Workshop: Microbeam Probes of Cellular Radiation Response, held at St. Catherine's College, University of Oxford, UK on March, 29th-31st, 2003. In 1993 the 4th LH Gray Workshop entitled ''Microbeam Probes of Cellular Radiation Response'' was held at the Gray Cancer Institute in Northwood. This was organized by Prof BD Michael, Dr M. Folkard and Dr KM Prise and brought together 40 participants interested in developing and applying new microbeam technology to problems in radiation biology (1). The workshop was an undoubted success and has spawned a series of subsequent workshops every two years. In the past, these workshops have been highly successful in bringing together groups interested in developing and applying micro-irradiation techniques to the study of cell and tissue damage by ionizing radiations. Following the first microbeam workshop, there has been a rapid growth in the number of centres developing radiobiology microbeams, or planning to do so and there are currently 15-20 worldwide. Much of the recent research using microbeams has used them to study low-dose effects and ''non-targeted'' responses such bystander effects, genomic instability and adaptive responses. The …
Date: January 1, 2004
Creator: Prise, Dr Kevin M.
System: The UNT Digital Library
AB INITIO AND CALPHAD THERMODYNAMICS OF MATERIALS (open access)

AB INITIO AND CALPHAD THERMODYNAMICS OF MATERIALS

Ab initio electronic structure methods can supplement CALPHAD in two major ways for subsequent applications to stability in complex alloys. The first one is rather immediate and concerns the direct input of ab initio energetics in CALPHAD databases. The other way, more involved, is the assessment of ab initio thermodynamics {acute a} la CALPHAD. It will be shown how these results can be used within CALPHAD to predict the equilibrium properties of multi-component alloys.
Date: April 14, 2004
Creator: Turchi, P A
System: The UNT Digital Library
Ab Initio No-Core Shell Model Calculations Using Realistic Two- and Three-Body Interactions (open access)

Ab Initio No-Core Shell Model Calculations Using Realistic Two- and Three-Body Interactions

There has been significant progress in the ab initio approaches to the structure of light nuclei. One such method is the ab initio no-core shell model (NCSM). Starting from realistic two- and three-nucleon interactions this method can predict low-lying levels in p-shell nuclei. In this contribution, we present a brief overview of the NCSM with examples of recent applications. We highlight our study of the parity inversion in {sup 11}Be, for which calculations were performed in basis spaces up to 9{Dirac_h}{Omega} (dimensions reaching 7 x 10{sup 8}). We also present our latest results for the p-shell nuclei using the Tucson-Melbourne TM three-nucleon interaction with several proposed parameter sets.
Date: November 30, 2004
Creator: Navratil, P; Ormand, W E; Forssen, C & Caurier, E
System: The UNT Digital Library
Ab Initio Studies of Polarization and Piezoelectricity in Vinylidene Fluoride and BN-Based Polymers (open access)

Ab Initio Studies of Polarization and Piezoelectricity in Vinylidene Fluoride and BN-Based Polymers

Article on ab initio studies of polarization and piezoelectricity in vinylidene fluoride and BN-based polymers.
Date: 2004
Creator: Nakhmanson, Serge M.; Buongiorno Nardelli, Marco & Bernholc, Jerry
System: The UNT Digital Library
Ab initio study of Al(III) adsorption on stepped {100} surfaces of KDP crystals (open access)

Ab initio study of Al(III) adsorption on stepped {100} surfaces of KDP crystals

Crystals of potassium dihydrogen phosphate (KH{sub 2}PO{sub 4}, KDP) are grown in large scale for use as nonlinear material in laser components. Traces of trivalent metal impurities are often added to the supernatant to achieve habit control during crystal growth, selectively inhibiting the growth of the {l_brace}100{r_brace} face. Model systems representing AlPO{sub 4}-doped KDP {l_brace}100{r_brace} stepped surfaces are prepared and studied using ab initio quantum methods. Results of Hartree-Fock partial optimizations are presented, including estimated energies of ion pair binding to the steps. We find that the PO{sub 4}{sup 3-} ion takes a position not unlike that of a standard phosphate in the crystal lattice, while the aluminum atom is displaced far from a K{sup +} ion position to establish coordinations with the PO{sub 4}{sup 3-} ion and to bind with another lattice-bound phosphate. Our optimized structures suggest that it is the formation of a fourth coordination of Al(III) to a third phosphate ion from solution, or perhaps from a nearby position in the lattice, that disrupts further deposition, pinning the steps.
Date: April 1, 2004
Creator: Salter, E A; Wierzbicki, A & Land, T A
System: The UNT Digital Library
Ab initio study of low-energy electron collisions withtertafluoroethene, C2F4 (open access)

Ab initio study of low-energy electron collisions withtertafluoroethene, C2F4

We report the results of variational calculations of elastic electron scattering by tetrafluoroethene, C{sub 2}F{sub 4}, with incident electron energies ranging from 0.5 to 20 eV, using the complex Kohn method and effective core potentials. These are the first fully calculations to reproduce experimental angular differential cross sections at energies below 10 eV. Low-energy electron scattering by C{sub 2}F{sub 4} is sensitive to the inclusion of electronic correlation and target-distortion effects. We therefore present results that describe the dynamic polarization of the target by the incident electron. The calculated cross sections are compared with recent experimental measurements.
Date: April 26, 2004
Creator: Trevisan, C. S.; Orel, A. E. & Rescigno, Thomas N.
System: The UNT Digital Library
Ab initio transport properties of nanostructures from maximally localized Wannier functions (open access)

Ab initio transport properties of nanostructures from maximally localized Wannier functions

Article on ab initio transport properties of nanostructures from maximally localized Wannier functions.
Date: January 22, 2004
Creator: Calzolari, Arrigo; Marzari, Nicola; Souza, Ivo & Buongiorno Nardelli, Marco
System: The UNT Digital Library
Absorption and Emission in the Non-Poissonian Case (open access)

Absorption and Emission in the Non-Poissonian Case

Article on absorption and emission in the Non-Poissonian Case.
Date: July 28, 2004
Creator: Aquino, Gerardo; Palatella, Luigi & Grigolini, Paolo
System: The UNT Digital Library
Abstracts for the Workshop on Computational Biology: Focus on Hydrogen, Biomass, and Nanoscience (open access)

Abstracts for the Workshop on Computational Biology: Focus on Hydrogen, Biomass, and Nanoscience

Computational science stands at the forefront of biological modeling and simulation. The challenges in this field are two-fold. First, biological computational science is obliged to use high-performance computers and advanced visualization to explore ever increasingly complex systems and datasets. Second, validation of theory with experiment is exceptionally critical in this new field. The Computational Sciences Center (CSC) is supporting the NREL Computational Sciences Workshop (NCS 2004) on Computational Biology to facilitate understanding and enhancement of the capabilities of computational science in research as well as the needs of the more traditional methods of scientific investigation, theory and experiment. The workshop aims to bring together researchers from scientific areas studying biological systems to discuss problems and potential solutions, to identify new issues, and to shape future directions for research. There are four technical sessions. Topics include: (1) Simulation and Modeling in Biomass Conversion; (2) Simulation and Modeling in Photobiology; (3) Bioinformatics for Renewable Energy; and (4) Modeling Hard- Soft-Matter Interfaces.
Date: September 1, 2004
Creator: Kim, K.; Jones, W.; Himmel, M. & King, P.
System: The UNT Digital Library
Accelerating the Reduction of Excess Russian Highly Enriched Uranium (open access)

Accelerating the Reduction of Excess Russian Highly Enriched Uranium

This paper presents the latest information on one of the Accelerated Highly Enriched Uranium (HEU) Disposition initiatives that resulted from the May 2002 Summit meeting between Presidents George W. Bush and Vladimir V. Putin. These initiatives are meant to strengthen nuclear nonproliferation objectives by accelerating the disposition of nuclear weapons-useable materials. The HEU Transparency Implementation Program (TIP), within the National Nuclear Security Administration (NNSA) is working to implement one of the selected initiatives that would purchase excess Russian HEU (93% 235U) for use as fuel in U.S. research reactors over the next ten years. This will parallel efforts to convert the reactors' fuel core from HEU to low enriched uranium (LEU) material, where feasible. The paper will examine important aspects associated with the U.S. research reactor HEU purchase. In particular: (1) the establishment of specifications for the Russian HEU, and (2) transportation safeguard considerations for moving the HEU from the Mayak Production Facility in Ozersk, Russia, to the Y-12 National Security Complex in Oak Ridge, TN.
Date: February 18, 2004
Creator: Benton, J; Wall, D; Parker, E & Rutkowski, E
System: The UNT Digital Library
ACCELERATION OF POLARIZED BEAMS USING MULTIPLE STRONG PARTIAL SIBERIAN SNAKES. (open access)

ACCELERATION OF POLARIZED BEAMS USING MULTIPLE STRONG PARTIAL SIBERIAN SNAKES.

Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult since depolarizing spin resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions. Using a 20-30% partial Siberian snake both imperfection and intrinsic resonances can be overcome. Such a strong partial Siberian snake was designed for the Brookhaven AGS using a dual pitch helical superconducting dipole. Multiple strong partial snakes are also discussed for spin matching at beam injection and extraction.
Date: July 5, 2004
Creator: ROSER,T. AHRENS,L. BAI,M. ET AL.
System: The UNT Digital Library
Acceleration of Polarized Beams Using Multiple Strong Partial Siberian Snakes (open access)

Acceleration of Polarized Beams Using Multiple Strong Partial Siberian Snakes

Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult since depolarizing spin resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions. Using a 20-30% partial Siberian snake both imperfection and intrinsic resonances can be overcome. Such a strong partial Siberian snake was designed for the Brookhaven AGS using a dual pitch helical superconducting dipole. Multiple strong partial snakes are also discussed for spin matching at beam injection and extraction.
Date: October 10, 2004
Creator: Roser, T.; Ahrens, L.; Bai, M.; Courant, E.; Glenn, J. W.; Gupta, R. C. et al.
System: The UNT Digital Library
Acceleressence: Dark energy from a phase transition at the seesawscale (open access)

Acceleressence: Dark energy from a phase transition at the seesawscale

Simple models are constructed for ''acceleressence'' dark energy: the latent heat of a phase transition occurring in a hidden sector governed by the seesaw mass scale v{sup 2}/M{sub Pl}, where v is the electroweak scale and M{sub Pl} the gravitational mass scale. In our models, the seesaw scale is stabilized by supersymmetry, implying that the LHC must discover superpartners with a spectrum that reflects a low scale of fundamental supersymmetry breaking. Newtonian gravity may be modified by effects arising from the exchange of fields in the acceleressence sector whose Compton wavelengths are typically of order the millimeter scale. There are two classes of models. In the first class the universe is presently in a metastable vacuum and will continue to inflate until tunneling processes eventually induce a first order transition. In the simplest such model, the range of the new force is bounded to be larger than 25 {micro}m in the absence of fine-tuning of parameters, and for couplings of order unity it is expected to be {approx} 100 {micro}m. In the second class of models thermal effects maintain the present vacuum energy of the universe, but on further cooling, the universe will ''soon'' smoothly relax to a matter dominated …
Date: October 5, 2004
Creator: Chacko, Z.; Hall, Lawrence J. & Nomura, Yasunori
System: The UNT Digital Library
Accessing High Pressure States Relevant to Core Conditions in the Giant Planets (open access)

Accessing High Pressure States Relevant to Core Conditions in the Giant Planets

We have designed an experimental technique to use on the National Ignition Facility (NIF) laser to achieve very high pressure (P{sub max} > 10 Mbar = 1000 GPa), dense states of matter at moderate temperatures (kT < 0.5 eV = 6000 K), relevant to the core conditions of the giant planets. A discussion of the conditions in the interiors of the giant planets is given, and an experimental design that can approach those conditions is described.
Date: April 15, 2004
Creator: Remington, B. A.; Cavallo, R. M.; Edwards, M. J.; Ho, D. D.; Lorenz, K. T.; Lorenzana, H. E. et al.
System: The UNT Digital Library
Accessing Ultra-High Pressure, Quasi-Isentropic States of Matter (open access)

Accessing Ultra-High Pressure, Quasi-Isentropic States of Matter

A new approach to the study of material strength of metals at extreme pressures has been developed on the Omega laser, using a ramped plasma piston drive. The laser drives a shock through a solid plastic reservoir that unloads at the rear free surface, expands across a vacuum gap, and stagnates on the metal sample under study. This produces a gently increasing ram pressure, compressing the sample nearly isentropically. The peak pressure on the sample, inferred from VISAR measurements of velocity, can be varied by adjusting the laser energy and pulse length, gap size, and reservoir density, and obeys a simple scaling relation. In an important application, using in-flight x-ray radiography, the material strength of solid-state samples at high pressure can be inferred by measuring the reductions in the growth rates (stabilization) of Rayleigh-Taylor (RT) unstable interfaces. This paper reports the first attempt to use this new laser-driven, quasi-isentropic technique for determining material strength in high-pressure solids. Modulated foils of Al-6061-T6 were accelerated and compressed to peak pressures of 200 kbar. Modulation growth was recorded at a series of times after peak acceleration and well into the release phase. Fits to the growth data, using a Steinberg-Guinan (SG) constitutive strength …
Date: November 12, 2004
Creator: Lorenz, K. T.; Edwards, M. J.; Glendinning, S. G.; Ho, D. D.; Jankowski, Alan Frederic; McNaney, J. et al.
System: The UNT Digital Library
Accounting for fuel price risk when comparing renewable togas-fired generation: the role of forward natural gas prices (open access)

Accounting for fuel price risk when comparing renewable togas-fired generation: the role of forward natural gas prices

Unlike natural gas-fired generation, renewable generation (e.g., from wind, solar, and geothermal power) is largely immune to fuel price risk. If ratepayers are rational and value long-term price stability, then--contrary to common practice--any comparison of the levelized cost of renewable to gas-fired generation should be based on a hedged gas price input, rather than an uncertain gas price forecast. This paper compares natural gas prices that can be locked in through futures, swaps, and physical supply contracts to contemporaneous long-term forecasts of spot gas prices. We find that from 2000-2003, forward gas prices for terms of 2-10 years have been considerably higher than most contemporaneous long-term gas price forecasts. This difference is striking, and implies that comparisons between renewable and gas-fired generation based on these forecasts over this period have arguably yielded results that are biased in favor of gas-fired generation.
Date: July 17, 2004
Creator: Bolinger, Mark; Wiser, Ryan & Golove, William
System: The UNT Digital Library
Accumulation and altered localization of telomere-associated protein TRF2 in immortally transformed and tumor-derived human breast cells (open access)

Accumulation and altered localization of telomere-associated protein TRF2 in immortally transformed and tumor-derived human breast cells

We have used cultured human mammary epithelial cells (HMEC) and breast tumor-derived lines to gain information on defects that occur during breast cancer progression. HMEC immortalized by a variety of agents (the chemical carcinogen benzo(a)pyrene, oncogenes c-myc and ZNF217, and/or dominant negative p53 genetic suppressor element GSE22) displayed marked up regulation (10-15 fold) of the telomere binding protein, TRF2. Up-regulation of TRF2 protein was apparently due to differences in post-transcriptional regulation, as mRNA levels remained comparable in finite life span and immortal HMEC. TRF2 protein was not up-regulated by the oncogenic agents alone in the absence of immortalization, nor by expression of exogenously introduced hTERT genes. We found TRF2 levels to be at least 2-fold higher than in control cells in 11/15 breast tumor cell lines, suggesting that elevated TRF2 levels are a frequent occurrence during the transformation of breast tumor cells in vivo. The dispersed distribution of TRF2 throughout the nuclei in some immortalized and tumor-derived cells indicated that not all the TRF2 was associated with telomeres in these cells. The process responsible for accumulation of TRF2 in immortalized HMEC and breast tumor-derived cell lines may promote tumorigenesis by contributing to the cells ability to maintain an indefinite life …
Date: December 23, 2004
Creator: Nijjar, Tarlochan; Bassett, Ekaterina; Garbe, James; Takenaka, Yasuhiro; Stampfer, Martha R.; Gilley, David et al.
System: The UNT Digital Library
An accumulator/compressor ring for Ne+ ions (open access)

An accumulator/compressor ring for Ne+ ions

The primary goal of the High Energy Density Physics (HEDP) program is to create an extremely bright ion beam at low duty cycle. For example, a typical set of parameters is: (1) Particle type = Ne{sup +}; (2) Ion energy = 20.1 MeV; (3) One ion pulse = 1 {micro}C, 1 ns, 1 mm{sup 2}; and (4) Repetition rate = 1 Hz. This would give a volume density of {approx}10{sup 12} particles/mm{sup 3}, which is several orders of magnitude higher than any existing proton machines (typically 10{sup 8}-10{sup 9} particles/mm{sup 3}, see reference [1]). On the other hand, however, the beam power is very low. At 20.1 MeV, 1 {micro}C and 1 Hz, one has: Beam power = 20.1 W. This leads to the following observation: In an HEDP machine, beam loss is a non-issue. This has important implication in the machine design. The machine is fundamentally different from those high power ({approx} MW) proton machines such as PSR, ISIS, SNS, RIA, GSI and JPARC, of which the machine design is dominated by beam loss control. A second observation is that, as it stands now, the HEDP program has limited funds (several $M). The hardware design needs to be as …
Date: November 1, 2004
Creator: Chou, Weiren
System: The UNT Digital Library