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Purgatorio - A new implementation of the Inferno algorithm (open access)

Purgatorio - A new implementation of the Inferno algorithm

For astrophysical applications, as well as modeling laser-produced plasmas, there is a continual need for equation-of-state data over a wide domain of physical conditions. This paper presents algorithmic aspects for computing the Helmholtz free energy of plasma electrons for temperatures spanning from a few Kelvin to several KeV, and densities ranging from essentially isolated ion conditions to such large compressions that most bound orbitals become delocalized. The objective is high precision results in order to compute pressure and other thermodynamic quantities by numerical differentiation. This approach has the advantage that internal thermodynamic self-consistency is ensured, regardless of the specific physical model, but at the cost of very stringent numerical tolerances for each operation. The computational aspects we address in this paper are faced by any model that relies on input from the quantum mechanical spectrum of a spherically symmetric Hamiltonian operator. The particular physical model we employ is that of INFERNO; of a spherically averaged ion embedded in jellium. An overview of PURGATORIO, a new implementation of the INFERNO equation of state model, is presented. The new algorithm emphasizes a novel decimation scheme for automatically resolving the structure of the continuum density of states, circumventing limitations of the pseudo-R matrix …
Date: March 29, 2005
Creator: Wilson, B; Sonnad, V; Sterne, P & Isaacs, W
System: The UNT Digital Library
Stragegies to Detect Hidden Geothermal Systems Based on Monitoringand Analysis of CO2 in the Near-Surface Environment (open access)

Stragegies to Detect Hidden Geothermal Systems Based on Monitoringand Analysis of CO2 in the Near-Surface Environment

We investigate the potential for CO2 monitoring in thenear-surface environment as an approach to exploration for hiddengeothermal systems. Numerical simulations of CO2 migration from a modelhidden geothermal system show that CO2 concentrations can reach highlevels in the shallow subsurface even for relatively low CO2 fluxes.Therefore, subsurface measurements offer an advantage over above-groundmeasurements which are affected by winds that rapidly disperse CO2. Tomeet the challenge of detecting geothermal CO2 emissions within thenatural background variability of CO2, we propose an approach thatintegrates available detection and monitoring techniques with statisticalanalysis and modeling.
Date: March 29, 2005
Creator: Lewicki, Jennifer L. & Oldenburg, Curtis M.
System: The UNT Digital Library
Using measured equipment load profiles to 'right-size' HVACsystems and reduce energy use in laboratory buildings (Pt. 2) (open access)

Using measured equipment load profiles to 'right-size' HVACsystems and reduce energy use in laboratory buildings (Pt. 2)

There is a general paucity of measured equipment load datafor laboratories and other complex buildings and designers often useestimates based on nameplate rated data or design assumptions from priorprojects. Consequently, peak equipment loads are frequentlyoverestimated, and load variation across laboratory spaces within abuilding is typically underestimated. This results in two design flaws.Firstly, the overestimation of peak equipment loads results in over-sizedHVAC systems, increasing initial construction costs as well as energy usedue to inefficiencies at low part-load operation. Secondly, HVAC systemsthat are designed without accurately accounting for equipment loadvariation across zones can significantly increase simultaneous heatingand cooling, particularly for systems that use zone reheat fortemperature control. Thus, when designing a laboratory HVAC system, theuse of measured equipment load data from a comparable laboratory willsupport right-sizing HVAC systems and optimizing their configuration tominimize simultaneous heating and cooling, saving initial constructioncosts as well as life-cycle energy costs.In this paper, we present datafrom recent studies to support the above thesis. We first presentmeasured equipment load data from two sources: time-series measurementsin several laboratory modules in a university research laboratorybuilding; and peak load data for several facilities recorded in anational energy benchmarking database. We then contrast this measureddata with estimated values that are typically used …
Date: June 29, 2005
Creator: Mathew, Paul; Greenberg, Steve; Frenze, David; Morehead, Michael; Sartor, Dale & Starr, William
System: The UNT Digital Library
Shape transitions in neutron-rich Ru isotopes: spectroscopy of 109,110,111,112Ru (open access)

Shape transitions in neutron-rich Ru isotopes: spectroscopy of 109,110,111,112Ru

The spectroscopy of neutron-rich {sup 109,110,111,112}Ru nuclei was studied by measuring the prompt {gamma} rays originated from fission fragments, produced by the {sup 238}U({alpha},f) fusion-fission reaction, in coincidence with the detection of both fragments. For {sup 109,111}Ru, both the negative-parity (h{sub 11/2} orbitals) and positive-parity (g{sub 7/2} and/or d{sub 5/2} orbitals) bands were extended to substantially higher spin and excitation energy than known previously. The ground-state and {gamma}-vibrational bands of {sup 110,112}Ru also were extended to higher spin, allowing observation of the second band crossing at the rotational frequency of {approx}450 keV in {sup 112}Ru, which is {approx}50 keV above the first band crossing. At a similar rotational frequency, the first band crossing for the h{sub 11/2} band in {sup 111}Ru was observed, which is absent in {sup 109}Ru. These band crossings most likely are caused by the alignment of the g{sub 9/2} proton pair. This early onset of the band crossing for the aligned {pi}g{sub 9/2} orbitals may be evidence of a triaxial shape transition from prolate to oblate occurring in {sup 111}Ru. The data together with a comparison of cranked shell model predictions are presented.
Date: June 29, 2005
Creator: Hua, H.; Cline, D.; Hayes, A. B.; Teng, R.; Riley, D.; Clark, R. M. et al.
System: The UNT Digital Library
Establishing Ergonomics in Industrially Developing Countries (open access)

Establishing Ergonomics in Industrially Developing Countries

The introduction of ergonomics is an ongoing effort in industrially developing countries and will ultimately require an organized, programmatic approach spanning several countries and organizations. Our preliminary efforts with our partner countries of Viet Nam, Thailand, and Nicaragua have demonstrated that a one-time course is just the first step in a series of necessary events to provide skills and create an infrastructure that will have lasting impact for the host country. To facilitate that any sort of training has a lasting impact, it is recommended that host countries establish a 'contract' with class participants and the guest instructors for at least one follow-up visit so instructors can see the progress and support the participants in current and future efforts. With repeated exchanges, the class participants can become the 'in country experts' and the next generation of ergonomic trainers. Additionally, providing participants with an easy to use hazard assessment tool and methods for evaluating the financial impact of the project (cost/benefit analysis) will assist increase the likelihood of success and establish a foundation for future projects. In the future, developing trade and regionally/culturally specific 'ergonomics toolkits' can help promote broader implementation, especially where training resources may be limited.
Date: August 29, 2005
Creator: Stewart, K.; Silverstein, B. & Kiefer, M.
System: The UNT Digital Library
Dynamic Response of Copper Subjected to Quasi-Isentropic, Gas-Gun Driven Loading (open access)

Dynamic Response of Copper Subjected to Quasi-Isentropic, Gas-Gun Driven Loading

A transmission electron microscopy study of quasi-isentropic high-pressure loading (peak pressures between 18 GPa and 52 GPa) of polycrystalline and monocrystalline copper was carried out. Deformation mechanisms and defect substructures at different pressures were analyzed. Current evidence suggests a deformation substructure consisting of twinning at the higher pressures and heavily dislocated laths and dislocation cells at the intermediate and lower pressures, respectively. Evidence of stacking faults at the intermediate pressures was also found. Dislocation cell sizes decreased with increasing pressure and increased with distance away from the surface of impact.
Date: September 29, 2005
Creator: Jarmakani, H.; McNaney, J. M.; Schneider, M. S.; Orlikowski, D.; Nguyen, J. H.; Kad, B. et al.
System: The UNT Digital Library
Calibration of symmetric and non-symmetric errors for interferometry of ultra-precise imaging systems (open access)

Calibration of symmetric and non-symmetric errors for interferometry of ultra-precise imaging systems

The azimuthal Zernike coefficients for shells of Zernike functions with shell numbers n<N may be determined by making measurements at N equally spaced rotational positions. However, these measurements do not determine the coefficients of any of the purely radial Zernike functions. Label the circle that the azimuthal Zernikes are measured in as circle A. Suppose that the azimuthal Zernike coefficients for n<N are also measured in a smaller circle B which is inside circle A but offset so that it is tangent to circle A and so that it has the center of circle A just inside its circular boundary. The diameter of circle B is thus only slightly larger than half the diameter of circle A. From these two sets of measurements, all the Zernike coefficients may be determined for n<N. However, there are usually unknown small rigid body motions of the optic between measurements. Then all the Zernike coefficients for n<N except for piston, tilts, and focus may be determined. We describe the exact mathematical algorithm that does this and describe an interferometer which measures the complete wavefront from pinholes in pinhole aligners. These pinhole aligners are self-contained units which include a fiber optic, focusing optics, and a …
Date: June 29, 2005
Creator: Phillion, D. W.; Sommargren, G. E.; Johnson, M. A.; Decker, T. A.; Taylor, J. S.; Gomie, Y et al.
System: The UNT Digital Library
Proceedings of the Workshop on Accelerator Driven High Energy Density Physics (open access)

Proceedings of the Workshop on Accelerator Driven High Energy Density Physics

None
Date: April 29, 2005
Creator: Barnard, J J
System: The UNT Digital Library
Branching Fraction for B0 -> pi- l+ nu and Determination of |Vub| in Upsilon(4S) -> B0 B0bar Events Tagged by B0bar -> D(*)+ l- nubar (open access)

Branching Fraction for B0 -> pi- l+ nu and Determination of |Vub| in Upsilon(4S) -> B0 B0bar Events Tagged by B0bar -> D(*)+ l- nubar

We report preliminary results from a study of the charmless exclusive semileptonic decay B{sup 0} {yields} {pi}{sup -}{ell}{sup +}{nu} based on the data collected at the {Upsilon}(4S) resonance using the BABAR detector at SLAC. The analysis uses events in which the signal B meson recoils against a B meson that has been reconstructed in a semileptonic decay {bar B}{sup 0} {yields} D{sup (*)+}{ell}{sup -}{bar {nu}}. We extract the total branching fraction {Beta}(B{sup 0} {yields} {pi}{sup -}{ell}{sup +}{nu}) = (1.03 {+-} 0.25{sub stat.} {+-} 0.13{sub syst.}) x 10{sup -4} and the partial branching fractions in three bins of q{sup 2}, the invariant mass squared of the lepton-neutrino system. From the partial branching fractions and theoretical predictions for the form factors, we determine the magnitude of the CKM matrix element |V{sub ub}|. We find |V{sub ub}| = (3.3 {+-} 0.4{sub stat.} {+-} 0.2{sub syst.} {sub -0.4}{sup +0.8}FF) x 10{sup -3}, where the last error is due to normalization of the form factor.
Date: June 29, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Deducing the 237U(n,f) cross-section using the Surrogate Ratio Method (open access)

Deducing the 237U(n,f) cross-section using the Surrogate Ratio Method

The authors have deduced the cross section for {sup 237}U(n,f) over an equivalent neutron energy range from 0 to 20 MeV using the Surrogate Ratio method. A 55 MeV {sup 4}He beam from the 88 Inch Cyclotron at Lawrence Berkeley National Laboratory was used to induce fission in the following reactions: {sup 238}U({alpha},{alpha}{prime}f) and {sup 236}U({alpha},{alpha}{prime}f). The {sup 238}U reaction was a surrogate for {sup 237}U(n,f) and the {sup 236}U reaction was used as a surrogate for {sup 235}U(n,f). Scattered alpha particles were detected in a fully depleted segmented silicon telescope array (STARS) over an angle range of 35{sup o} to 60{sup o} with respect to the beam axis. The fission fragments were detected in a third independent silicon detector located at backward angles between 106{sup o} and 131{sup o}.
Date: December 29, 2005
Creator: Burke, J. T.; Bernstein, L. A.; Escher, J.; Ahle, L.; Church, J. A.; Dietrich, F. S. et al.
System: The UNT Digital Library
Nuclear Physics from Scratch (open access)

Nuclear Physics from Scratch

We report on applications of the ab initio, no-core shell model with the primary goal of achieving an accurate description of nuclear structure and reactions from the fundamental inter-nucleon interactions. We show that realistic two-nucleon interactions are inadequate to describe the low-lying structure of {sup 10}B, and that realistic three-nucleon interactions are essential. We report preliminary attempts to compute astrophysical S-factors
Date: April 29, 2005
Creator: Ormand, W; Navratil, P; Forssen, C & Bertulani, C
System: The UNT Digital Library
Shift Dependent Skew Quadrupole in Advanced Light SourceElliptically Polarizing Undulators, Cause and Corrections (open access)

Shift Dependent Skew Quadrupole in Advanced Light SourceElliptically Polarizing Undulators, Cause and Corrections

Three elliptically polarizing undulators (EPU) are installed and operational at the Advanced Light Source (ALS); the most recent was installed in April 2005. Operational experience has shown a variation in electron beam size which correlates with the EPU's magnetic quadrant shifts used to vary polarization. Storage ring electron dynamics studies pointed to the existence of a shift dependent skew quadrupole (SQ) component generated within the EPUs. Detailed magnetic and mechanical measurements demonstrated that the field errors were the result of systematic individual magnetic block displacements which vary with quadrant shift. This paper will discuss the results of electron dynamics studies, magnetic and mechanical measurements, design modifications planned for future EPUs to eliminate the SQ source, and the design and implementation of SQ compensation coils.
Date: November 29, 2005
Creator: Marks, Steve; Prestemon, Soren; Robin, David; Schlueter, Ross D.; Steier, Christoph; Wolski, Andrew et al.
System: The UNT Digital Library
Charm Physics at BaBar (open access)

Charm Physics at BaBar

Large production of the c{bar c} pairs and high integrated luminosity make the PEPII B Factory an excellent place for studying the charm hadrons. In this paper, we present a few most recent results from BaBar collaboration in charm sector.
Date: June 29, 2005
Creator: Chen, Chunhui
System: The UNT Digital Library
Comparison of Design and Practices for Radiation Safety among Five Synchrotron Radiation Facilities (open access)

Comparison of Design and Practices for Radiation Safety among Five Synchrotron Radiation Facilities

There are more and more third-generation synchrotron radiation (SR) facilities in the world that utilize low emittance electron (or positron) beam circulating in a storage ring to generate synchrotron light for various types of experiments. A storage ring based SR facility consists of an injector, a storage ring, and many SR beamlines. When compared to other types of accelerator facilities, the design and practices for radiation safety of storage ring and SR beamlines are unique to SR facilities. Unlike many other accelerator facilities, the storage ring and beamlines of a SR facility are generally above ground with users and workers occupying the experimental floor frequently. The users are generally non-radiation workers and do not wear dosimeters, though basic facility safety training is required. Thus, the shielding design typically aims for an annual dose limit of 100 mrem over 2000 h without the need for administrative control for radiation hazards. On the other hand, for operational and cost considerations, the concrete ring wall (both lateral and ratchet walls) is often desired to be no more than a few feet thick (with an even thinner roof). Most SR facilities have similar operation modes and beam parameters (both injection and stored) for storage …
Date: June 29, 2005
Creator: Liu, James C.; Rokni, Sayed H.; Asano, Yoshihiro; Casey, William R. & Donahue, Richard J.
System: The UNT Digital Library
Measurement of the B+- --> rho+- pi0 Branching Fraction and Direct CP Asymmetry (open access)

Measurement of the B+- --> rho+- pi0 Branching Fraction and Direct CP Asymmetry

An improved measurement of the process B{sup {+-}} {yields} {rho}{sup {+-}}{pi}{sup 0} is presented. The data sample of 211 fb{sup -1} comprises 232 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. The yield and CP asymmetry are calculated using an extended maximum likelihood fitting method. The branching fraction and asymmetry are found to be {Beta}(B{sup {+-}} {yields} {rho}{sup {+-}}{pi}{sup 0}) = [10.0 {+-} 1.4 (Stat.) {+-} 0.9 (Syst.)] x 10{sup -6} and {Alpha}{sub CP}(B{sup {+-}} {yields} {rho}{sup {+-}}{pi}{sup 0}) = -0.01 {+-} 0.13 (Stat.) {+-} 0.02 (Syst.), superseding previous measurements. The statistical significance of the signal is calculated to be 8.7{sigma}.
Date: June 29, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Kinetics of carboplatin-DNA binding in genomic DNA and bladder cancer cells as determined by accelerator mass spectrometry (open access)

Kinetics of carboplatin-DNA binding in genomic DNA and bladder cancer cells as determined by accelerator mass spectrometry

Cisplatin and carboplatin are platinum-based drugs that are widely used in cancer chemotherapy. The cytotoxicity of these drugs is mediated by platinum-DNA monoadducts and intra- and interstrand diadducts, which are formed following uptake of the drug into the nucleus of cells. The pharmacodynamics of carboplatin display fewer side effects than for cisplatin, albeit with less potency, which may be due to differences in rates of DNA adduct formation. We report the use of accelerator mass spectrometry (AMS), a sensitive detection method often used for radiocarbon quantitation, to measure both the kinetics of [{sup 14}C]carboplatin-DNA adduct formation with genomic DNA and drug uptake and DNA binding in T24 human bladder cancer cells. Only carboplatin-DNA monoadducts contain radiocarbon in the platinated DNA, which allowed for calculation of kinetic rates and concentrations within the system. The percent of radiocarbon bound to salmon sperm DNA in the form of monoadducts was measured by AMS over 24 h. Knowledge of both the starting concentration of the parent carboplatin and the concentration of radiocarbon in the DNA at a variety of time points allowed calculation of the rates of Pt-DNA monoadduct formation and conversion to toxic cross-links. Importantly, the rate of carboplatin-DNA monoadduct formation was approximately …
Date: December 29, 2005
Creator: Hah, S S; Stivers, K M; Vere White, R & Henderson, P T
System: The UNT Digital Library
Band Structure Parameters and Fermi Resonances of Exciton-Polaritons in CsI and CsBr under Hydrostatic Pressure (open access)

Band Structure Parameters and Fermi Resonances of Exciton-Polaritons in CsI and CsBr under Hydrostatic Pressure

Most alkali halides crystallize in the fcc sodium chloride structure. In contrast, with the exception of CsF, the Cs-halides form the simple cubic cesium chloride (CsCl) structure at ambient conditions and they have a substantially different electronic structure than other alkali halides; in particular, they have several nearly degenerate electronic levels near the Brillouin zone center. Highly resolved Three-Photon Spectroscopy (TPS) measurements allow direct observation of the near band edge structure and, in the case of CsI, probe more states than one-photon techniques. A number of interesting phenomena, among them level repulsion (Fermi resonance), occur as these levels are tuned through one another by application of hydrostatic pressure. To the best of our knowledge, this has been observed for CsBr for the first time. Doubling the photon energy range compared to a previous publication [see Yoo et al. PRL 84, 3875 (2000)] allows direct observation of the n=1, 2 and 3 exciton-polariton members of the {Lambda}{sub 8}{sup -}-{Lambda}{sub 6}{sup +} transition in CsI and lets us establish unambiguous values for the bandgap (6.139 eV), binding energy (0.265 eV) and their pressure dependence up to 7 kbar. Similarly to CsI, the CsBr linewidth of the lowest {Lambda}{sub 4}{sup -} polariton (A) …
Date: November 29, 2005
Creator: Lipp, M J; Yoo, C H; Strachan, D & Daniels, W B
System: The UNT Digital Library
MICRON-SCALE DEEP HOLE DRILLING FOR BERYLLIUM CAPSULE FILL APPLICATIONS (open access)

MICRON-SCALE DEEP HOLE DRILLING FOR BERYLLIUM CAPSULE FILL APPLICATIONS

A laser processing system has been developed to drill high aspect ratio holes through the impermeable beryllium capsules envisioned for ignition shots on NIF. The drilling system was designed to produce holes with an entrance and exit diameter of approximately 5 {micro}m through the full 175 {micro}m thickness of the capsule. To meet these requirements, a frequency doubled femtosecond-class Ti:Sapphire laser is directed through a high numerical aperture lens to provide the spot geometry needed to drill the hole. The laser pulse is confined by the metallic walls of the hole, thereby maintaining the diameter of the channel well beyond the Rayleigh range of the optical system. Presented is the current state of this work-in-progress, including descriptions of the device and the technique used to produce the holes. The various means of characterizing the laser-drilled channels are also discussed.
Date: November 29, 2005
Creator: Armstrong, J P; Rubenchik, A M; Gunther, J & Stuart, B C
System: The UNT Digital Library
Image Correlation Applied to Single Crystal Plasticity Experiments and Comparison to Strain Gage Data (open access)

Image Correlation Applied to Single Crystal Plasticity Experiments and Comparison to Strain Gage Data

Full-field optical techniques are becoming increasingly popular for measuring the deformation of materials, especially in materials that exhibit non-uniform behavior. While there are many full-field techniques available (e.g. moire interferometry, electronic speckle pattern interferometry (ESPI), holography, and image correlation [1]), for our study of the deformation of single crystals, the image correlation technique was chosen for its insensitivity to vibrations and ability to measure large strains. While the theory and development of the algorithms for image correlation have been presented elsewhere [2,3] a comparative study to a conventional strain measurement device, such as a strain gage rosette, is desired to test the robustness and accuracy of the technique. The 6 Degrees of Freedom (6DOF) experiment, which was specifically designed to validate dislocation dynamics (DD) simulations [4], is ideally suited to compare the two methods. This experiment is different from previous experiments on single crystals in that it allows the crystal to deform essentially unconstrained, in both the elastic and plastic regimes, by allowing the bottom of the sample to move as the sample is being compressed. This unconstrained motion prevents the internal crystal planes from rotating during the deformation as typically seen in the pioneering work of Schmid [5] and …
Date: June 29, 2005
Creator: LeBlanc, M. M.; Florando, J. N.; Lassila, D. H.; Schmidt, T. & Tyson, J., II
System: The UNT Digital Library
Hands-on lessons in ergonomics for youth (open access)

Hands-on lessons in ergonomics for youth

Ergonomics risk factors apply to everybody. Numerous adults have experienced disabling injuries related to use of computers and other forms of technology. Now children are using technology even more than adults. Increasingly ergonomics risk factors are being recognized as present in the world of children. Outreach to schools and the surrounding community by employers may help protect the future work force. A growing body of researchers believe that children can benefit from the early introduction of ergonomics awareness and preventative measures. While individual representatives of the educational system may embrace the concept of introducing ergonomics into the classroom, a number of barriers can prevent implementation of integrated programs. Some of the barriers to introducing ergonomics in schools have been absence of a tie to educational standards, the existing demands on teaching hours, and the absence of easily executable lesson plans. Ergonomics is rarely included in teacher training and professional ergonomics expertise is needed for the development of a class-based program. As part of Strategic Vision plan for 2025, a National Laboratory identified community outreach and the future workforces as key areas for initiatives. A series of hands-on interactive modules have been developed by professional ergonomics specialists. They are being tested …
Date: September 29, 2005
Creator: Bennett, C; Alexandre, M & Jacobs, K
System: The UNT Digital Library
CONFERENCE PROPOSAL: “Time-Resolved Vibrational Spectroscopy XII” (open access)

CONFERENCE PROPOSAL: “Time-Resolved Vibrational Spectroscopy XII”

None
Date: August 29, 2005
Creator: Heilweil, Edwin J. & Gustafson, Terry L.
System: The UNT Digital Library
Russian Military and Security Forces: A Postulated Reaction to a Nuclear Detonation (open access)

Russian Military and Security Forces: A Postulated Reaction to a Nuclear Detonation

In this paper, we will examine how Russia's military and security forces might react to the detonation of a 10-kiloton nuclear weapon placed next to the walls surrounding the Kremlin. At the time of this 'big bang,' Putin is situated outside Moscow and survives the explosion. No one claims responsibility for the detonation. No other information is known. Numerous variables will determine how events ultimately unfold and how the military and security forces will respond. Prior to examining these variables in greater detail, it is imperative to elucidate first what we mean by Russia's military and security forces.
Date: April 29, 2005
Creator: Ball, D
System: The UNT Digital Library
Quantum-based Atomistic Simulation of Transition Metals (open access)

Quantum-based Atomistic Simulation of Transition Metals

First-principles generalized pseudopotential theory (GPT) provides a fundamental basis for transferable multi-ion interatomic potentials in d-electron transition metals within density-functional quantum mechanics. In mid-period bcc metals, where multi-ion angular forces are important to structural properties, simplified model GPT or MGPT potentials have been developed based on canonical d bands to allow analytic forms and large-scale atomistic simulations. Robust, advanced-generation MGPT potentials have now been obtained for Ta and Mo and successfully applied to a wide range of structural, thermodynamic, defect and mechanical properties at both ambient and extreme conditions of pressure and temperature. Recent algorithm improvements have also led to a more general matrix representation of MGPT beyond canonical bands allowing increased accuracy and extension to f-electron actinide metals, an order of magnitude increase in computational speed, and the current development of temperature-dependent potentials.
Date: August 29, 2005
Creator: Moriarty, J A; Benedict, L X; Glosli, J N; Hood, R Q; Orlikowski, D A; Patel, M V et al.
System: The UNT Digital Library
A Stringy Test of Flux-Induced Isometry Gauging (open access)

A Stringy Test of Flux-Induced Isometry Gauging

Supergravity analysis suggests that the effect of fluxes in string theory compactifications is to gauge isometries of the scalar manifold. However, isometries are generically broken by brane instanton effects. Here we demonstrate how fluxes protect exactly those isometries from quantum corrections which are gauged according to the classical supergravity analysis. We also argue that all other isometries are generically broken.
Date: June 29, 2005
Creator: Kashani-Poor, Amir-Kian & Tomasiello, Alessandro
System: The UNT Digital Library