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Edmonds et al. Reply (open access)

Edmonds et al. Reply

This article is a response to an article by M. Adell et al. [Phy. Rev. Lett. 94, 139701 (2005)] about semiconductor-based spintronics research.
Date: April 8, 2005
Creator: Edmonds, Kevin; Boguslawski, Piotr; Wang, K. Y.; Campion, Richard Paul; Novikov, Sergei; Farley, N. R. S. et al.
System: The UNT Digital Library
2005 DOE Hydrogen Program Review PresentationCOST AND PERFORMANCE ENHANCEMENTS FOR A PEM FUEL CELL TURBOCOMPRESSOR (open access)

2005 DOE Hydrogen Program Review PresentationCOST AND PERFORMANCE ENHANCEMENTS FOR A PEM FUEL CELL TURBOCOMPRESSOR

The objectives of the program during the past year was to complete Technical Objectives 2 and 3 and initiate Technical Objective 4 are described. To assist the Department of Energy in the development of a low cost, reliable and high performance air compressor/expander. Technical Objective 1: Perform a turbocompressor systems PEM fuel cell trade study to determine the enhanced turbocompressor approach. Technical Objective 2: Using the results from technical objective 1, an enhanced turbocompressor will be fabricated. The design may be modified to match the flow requirements of a selected fuel cell system developer. Technical Objective 3: Design a cost and performance enhanced compact motor and motor controller. Technical Objective 4: Turbocompressor/motor controller development.
Date: April 1, 2005
Creator: Gee, Mark K.
System: The UNT Digital Library
Multi-Model Combination techniques for Hydrological Forecasting: Application to Distributed Model Intercomparison Project Results (open access)

Multi-Model Combination techniques for Hydrological Forecasting: Application to Distributed Model Intercomparison Project Results

This paper examines several multi-model combination techniques: the Simple Multi-model Average (SMA), the Multi-Model Super Ensemble (MMSE), Modified Multi-Model Super Ensemble (M3SE) and the Weighted Average Method (WAM). These model combination techniques were evaluated using the results from the Distributed Model Intercomparison Project (DMIP), an international project sponsored by the National Weather Service (NWS) Office of Hydrologic Development (OHD). All of the multi-model combination results were obtained using uncalibrated DMIP model outputs and were compared against the best uncalibrated as well as the best calibrated individual model results. The purpose of this study is to understand how different combination techniques affect the skill levels of the multi-model predictions. This study revealed that the multi-model predictions obtained from uncalibrated single model predictions are generally better than any single member model predictions, even the best calibrated single model predictions. Furthermore, more sophisticated multi-model combination techniques that incorporated bias correction steps work better than simple multi-model average predictions or multi-model predictions without bias correction.
Date: April 11, 2005
Creator: Ajami, N. K.; Duan, Q.; Gao, X. & Sorooshian, S.
System: The UNT Digital Library
A Radiocarbon Chronology of Hunter-Gatherer Occupation from Bodega Bay, California, USA (open access)

A Radiocarbon Chronology of Hunter-Gatherer Occupation from Bodega Bay, California, USA

The evolution of hunter-gatherer maritime adaptations in western North America has been a prominent topic of discussion among archaeologists in recent years (e.g. Arnold 1992; Erlandson and Colten 1991; Erlandson and Glassow 1997; Lightfoot 1993). Although vast coastal regions of the northeastern Pacific (for example, southern California) have been investigated in detail, our understanding of hunter-gatherer developments along the coast of northern California is limited. Previous research indicates that humans have exploited marine mammals, fish and shellfish along the northern California shoreline since the early Holocene (Schwaderer 1992). By the end of the late Holocene, some groups remained year-round on the coast subsisting primarily on marine resources (e.g. Gould 1975; Hildebrandt and Levulett 2002). However, a paucity of well-dated cultural deposits has hindered our understanding of these developments, particularly during the early and middle Holocene. The lack of a long and reliable chronological sequence has restricted our interpretations of behavioral change, including the adaptive strategies (such as foraging, mobility and settlement) used by human foragers to colonize and inhabit the coastal areas of this region. These shortcomings have also hindered comparative interpretations with other coastal and inland regions in western North America. Here we present a Holocene radiocarbon chronology of …
Date: April 27, 2005
Creator: Kennedy, M. A.; Russell, A. D. & Guilderson, T. P.
System: The UNT Digital Library
A Beamline for High Pressure Studies at the Advanced Light Source With a Superconducting Bending Magnet as the Source (open access)

A Beamline for High Pressure Studies at the Advanced Light Source With a Superconducting Bending Magnet as the Source

A new facility for high-pressure diffraction and spectroscopy using diamond anvil high-pressure cells has been built at the Advanced Light Source on Beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 Tesla superconducting bending magnet (superbend). Useful x-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness preserving optics of the beamline. These optics are comprised of: a plane parabola collimating mirror (M1), followed by a Kohzu monochromator vessel with a Si(111) crystals (E/{Delta}E {approx} 7000) and a W/B{sub 4}C multilayer (E/{Delta}E {approx} 100), and then a toroidal focusing mirror (M2) with variable focusing distance. The experimental enclosure contains an automated beam positioning system, a set of slits, ion chambers, the sample positioning goniometry and area detectors (CCD or image-plate detector). Future developments aim at the installation of a second end station dedicated for in situ laser-heating on one hand and a dedicated high-pressure single-crystal station, applying both monochromatic as well as polychromatic techniques.
Date: April 21, 2005
Creator: Kunz, M.; MacDowell, A. A.; Caldwell, W. A.; Cambie, D.; Celestre, R. S.; Domning, E. E. et al.
System: The UNT Digital Library
Visualization of Force Fields in Protein StructurePrediction (open access)

Visualization of Force Fields in Protein StructurePrediction

The force fields used in molecular computational biology are not mathematically defined in such a way that their mathematical representation would facilitate the straightforward application of volume visualization techniques. To visualize energy, it is necessary to define a spatial mapping for these fields. Equipped with such a mapping, we can generate volume renderings of the internal energy states in a molecule. We describe our force field, the spatial mapping that we used for energy, and the visualizations that we produced from this mapping. We provide images and animations that offer insight into the computational behavior of the energy optimization algorithms that we employ.
Date: April 26, 2005
Creator: Crawford, Clark; Kreylos, Oliver; Hamann, Bernd & Crivelli, Silvia
System: The UNT Digital Library
Accelerator mass spectrometry for quantitative in vivo tracing (open access)

Accelerator mass spectrometry for quantitative in vivo tracing

Accelerator mass spectrometry (AMS) counts individual rare, usually radio-, isotopes such as radiocarbon at high efficiency and specificity in milligram-sized samples. AMS traces very low chemical doses ({micro}g) and radiative doses (100 Bq) of isotope labeled compounds in animal models and directly in humans for pharmaceutical, nutritional, or toxicological research. Absorption, metabolism, distribution, binding, and elimination are all quantifiable with high precision after appropriate sample definition.
Date: April 19, 2005
Creator: Vogel, J S
System: The UNT Digital Library
Development of a large aperture Nb3Sn racetrack quadrupolemagnet (open access)

Development of a large aperture Nb3Sn racetrack quadrupolemagnet

The U.S. LHC Accelerator Research Program (LARP), a collaboration between BNL, FNAL, LBNL, and SLAC, has among its major objectives the development of advanced magnet technology for an LHC luminosity upgrade. The LBNL Superconducting Magnet Group supports this program with a broad effort involving design studies, Nb{sub 3}Sn conductor development, mechanical models, and basic prototypes. This paper describes the development of a large aperture Nb{sub 3}Sn racetrack quadrupole magnet using four racetrack coils from the LBNL Subscale Magnet (SM) Program. The magnet provides a gradient of 95 T/m in a 110 mm bore, with a peak field in the conductor of 11.2 T. The coils are prestressed by a mechanical structure based on a pre-tensioned aluminum shell, and axially supported with aluminum rods. The mechanical behavior has been monitored with strain gauges and the magnetic field has been measured. Results of the test are reported and analyzed.
Date: April 14, 2005
Creator: Ferracin, Paolo; Bartlett, Scott E.; Caspi, Shlomo; Dietderich,Daniel R.; Gourlay, Steven A.; Hannaford, Charles R. et al.
System: The UNT Digital Library
Electrospray mass spectrometry of NeuAc oligomers associated with the C fragment of the tetanus toxin (open access)

Electrospray mass spectrometry of NeuAc oligomers associated with the C fragment of the tetanus toxin

The Clostridial neurotoxins, botulinum and tetanus, gain entry into neuronal cells by protein recognition involving cell specific binding sites. The sialic or N-acetylneuraminic acid (NeuAc) residues of gangliosides attached to the surface of motor neurons are the suspected recognition and interaction points with Clostridial neurotoxins, although not necessarily the only ones. We have used electrospray ionization mass spectrometry (ESIMS) to examine formation of complexes between the tetanus toxin C fragment, or targeting domain, and carbohydrates containing NeuAc groups to determine how NeuAc residues contribute to ganglioside binding. ESI-MS was used to rapidly and efficiently measure dissociation constants for a number of related NeuAc-containing carbohydrates and NeuAc oligomers, information that has helped identify the structural features of gangliosides that determine their binding to tetanus toxin. The strength of the interactions between the C fragment and (NeuAc){sub n}, are consistent with the topography of the targeting domain of tetanus toxin and the nature of its carbohydrate binding sites. The results suggest that the targeting domain of tetanus toxin contains two binding sites that can accommodate NeuAc (or a dimer). This study also shows that NeuAc must play an important role in ganglioside binding and molecular recognition, a process critical for normal cell …
Date: April 3, 2005
Creator: Prieto, M C; Whittal, R M; Baldwin, M A; Burlingame, A L & Balhorn, R
System: The UNT Digital Library
Melting of Transition Metals (open access)

Melting of Transition Metals

We review the transition melting studies carried out at Mainz, and describe a recently developed model used to explain that the relatively low melting slopes are due to the partially filled d-bands, and the persistence of the pressure induced s-d transition. The basic tenets of the model have now been reconfirmed by new measurements for Cu and Ni. The measurements show that Cu which has a filled 3d-band, has a melt slope that is about 2.5 greater than its neighbor Ni. In the case of Mo, the apparent discrepancy of DAC melting measurements with shock melting can be explained by accounting for the change in melt slope due to the bcc-cp transition observed in the shock studies. The Fe melt curve is revisited. The possible relevance of the Jahn-Teller effect and recently observed transition metal melts with Icosahedral Short-Range Order (ISRO) is discussed.
Date: April 11, 2005
Creator: Ross, M; Japel, S & Boehler, R
System: The UNT Digital Library
Correlation between Strand Stability and Magnet Performance (open access)

Correlation between Strand Stability and Magnet Performance

Magnet programs at BNL, LBNL and FNAL have observed instabilities in high J{sub c} Nb{sub 3}Sn strands and magnets made from these strands. This paper correlates the strand stability determined from a short sample-strand test to the observed magnet performance. It has been observed that strands that carry high currents at high fields (greater than 10T) cannot sustain these same currents at low fields (1-3T) when the sample current is fixed and the magnetic field is ramped. This suggests that the present generation of strand is susceptible to flux jumps (FJ). To prevent flux jumps from limiting stand performance, one must accommodate the energy released during a flux jump. To better understand FJ this work has focused on wire with a given sub-element diameter and shows that one can significantly improve stability by increasing the copper conductivity (higher residual resistivity ratio, RRR, of the Cu). This increased stability significantly improves the conductor performance and permits it to carry more current.
Date: April 16, 2005
Creator: Dietderich, Daniel R.; Bartlett, Scott E.; Caspi, Shlomo; Ferracin, Paolo; G ourlay, Stephen A.; Higley, Hugh C. et al.
System: The UNT Digital Library
A QSAR for the Mutagenic Potencies of Twelve 2-Amino-trimethylimidazopyridine Isomers: Structural, Quantum Chemical,and Hydropathic Factors (open access)

A QSAR for the Mutagenic Potencies of Twelve 2-Amino-trimethylimidazopyridine Isomers: Structural, Quantum Chemical,and Hydropathic Factors

An isomeric series of heterocyclic amines related to one found in heated muscle meats was investigated for properties that predict their measured mutagenic potency. Eleven of the 12 possible 2-amino-trimethylimidazopyridine (TMIP) isomers were tested for mutagenic potency in the Ames/Salmonella test with bacterial strain TA98, and resulted in a 600-fold range in potency. Structural, quantum chemical and hydropathic data were calculated on the parent molecules and the corresponding nitrenium ions of all of the tested isomers to establish models for predicting the potency of the unknown isomer. The regression model accounting for the largest fraction of the total variance in mutagenic potency contains four predictor variables: dipole moment, a measure of the gap between amine LUMO and HOMO energies, percent hydrophilic surface, and energy of amine LUMO. The most important determinants of high mutagenic potency in these amines are: (1) a small dipole moment, (2) the combination of b-face ring fusion and N3-methyl group, and (3) a lower calculated energy of the {pi} electron system. Based on predicted potency from the average of five models, the isomer not yet synthesized and tested is expected to have a mutagenic potency of 0.84 revertants/{micro}g in test strain TA98.
Date: April 23, 2005
Creator: Knize, M G; Hatch, F T; Tanga, M J; Lau, E V & Colvin, M E
System: The UNT Digital Library
Interference effect in elastic parton energy loss in a finitemedium (open access)

Interference effect in elastic parton energy loss in a finitemedium

Similar to the radiative parton energy loss due to gluonbremsstrahlung, elastic energy loss of a parton undergoing multiplescattering in a finite medium is demonstrated to be sensitive tointerference effect. The interference between amplitudes of elasticscattering via a gluon exchange and that of gluon radiation reduces theeffective elastic energy loss in a finite medium and gives rise to anon-trivial length dependence. The reduction is most significant for apropagation length L<4/\pi T in a medium with a temperature T. Thoughthe finite size effect is not significant for the average partonpropagation in the most central heavy-ion collisions, it will affect thecentrality dependence of its effect on jet quenching.
Date: April 18, 2005
Creator: Wang, Xin-Nian
System: The UNT Digital Library
Melting of Copper and Nickel at high pressure: the role of d-electrons (open access)

Melting of Copper and Nickel at high pressure: the role of d-electrons

Melting curves of Cu and Ni were measured to 97 GPa (3800 K) and 60 GPa (2970 K), respectively, in the laser-heated diamond cell. The measured melting temperatures of Cu are in good agreement with recent theoretical calculations. The melting slope (dT/dP) of Cu, which has a filled d-electron band, is about 2.5 times steeper than for Ni, which with one less electron, has a partially unfilled d-electron band. The relatively low melting slope obtained for Ni, measured using identical experimental methods as for Cu, is consistent with our previous measurements for other transition metals with partially filled d-bands, which are in serious disagreement with theoretical estimates. The present results confirm the key role d-shell electrons play in determining the high pressure melting curves.
Date: April 11, 2005
Creator: Japel, S; Boehler, R & Ross, M
System: The UNT Digital Library
Gamma-Ray Imaging With Coaxial HPGe Detector (open access)

Gamma-Ray Imaging With Coaxial HPGe Detector

We report on the first experimental demonstration of Compton imaging of gamma rays with a single coaxial high-purity germanium (HPGe) detector. This imaging capability is realized by two-dimensional segmentation of the outside contact in combination with digital pulse-shape analysis, which enables to image gamma rays in 4{pi} without employing a collimator. We are able to demonstrate the ability to image the 662keV gamma ray from a {sup 137}Cs source with preliminary event selection with an angular accuracy of 5 degree with an relative efficiency of 0.2%. In addition to the 4{pi} imaging capability, such a system is characterized by its excellent energy resolution and can be implemented in any size possible for Ge detectors to achieve high efficiency.
Date: April 12, 2005
Creator: Niedermayr, T.; Vetter, K.; Mihailescu, L.; Schmid, G. J.; Beckedahl, D.; Kammeraad, J. et al.
System: The UNT Digital Library
Is the beta phase maximal? (open access)

Is the beta phase maximal?

indicates that 2|Vub / Vcb/ Vus| = (1-z) with z given by z = 0.19 +(-) 0.14. This fact implies that irrespective of the form of the quark Yukawa matrices, the measured value of the SM CP phase beta is approximately the maximum allowed by the measured absolute values of the CKM elements. This is beta = pi/6 - z/sqrt{3} for gamma = pi/3 + z/sqrt{3}, which implies alpha = pi/2. Alternatively, assuming that beta is exactly maximal and using the experimental measurement, sin(2beta) = 0.726+(-) 0.037, the phase gamma is predicted to be gamma = pi/2 - beta = 66.3 +(-) 1.7. The maximality of beta, if confirmed by the near-future experiments, may give us some clues as to the origin of CP violation.
Date: April 20, 2005
Creator: Ferrandis, Javier & Ferrandis, Javier
System: The UNT Digital Library
Measurement of the azimuthal angle distribution of leptons from W boson decays as a function of the W transverse momentum in p anti-p collisions at s**(1/2) = 1.8-TeV (open access)

Measurement of the azimuthal angle distribution of leptons from W boson decays as a function of the W transverse momentum in p anti-p collisions at s**(1/2) = 1.8-TeV

We present the first measurement of the A{sub 2} and A{sub 3} angular coefficients of the W boson produced in proton-antiproton collisions. We study W {yields} ev{sub e} and W {yields} {mu}{nu}{sub {mu}} candidate events produced in association with at least one jet at CDF, during Run Ia and Run Ib of the Tevatron at {radical}s = 1.8 TeV. The corresponding integrated luminosity was 110 pb{sup -1}. The jet balances the transverse momentum of the W and introduces QCD effects in W boson production. The extraction of the angular coefficients is achieved through the direct measurement of the azimuthal angle of the charged lepton in the Collins-Soper rest-frame of the W boson. The angular coefficients are measured as a function of the transverse momentum of the W boson. The electron, muon, and combined results are in good agreement with the Standard Model prediction, up to order {alpha}{sub s}{sup 2} in QCD.
Date: April 1, 2005
Creator: Acosta, D.; Affolder, Anthony A.; Albrow, M. G.; Ambrose, D.; Amidei, D.; Anikeev, K. et al.
System: The UNT Digital Library
Characterization and Compensation of High Speed Digitizers (open access)

Characterization and Compensation of High Speed Digitizers

Increasingly, ADC technology is being pressed into service for single single-shot instrumentation applications that were formerly served by vacuum-tube based oscilloscopes and streak cameras. ADC technology, while convenient, suffers significant performance impairments. Thus, in these demanding applications, a quantitative and accurate representation of these impairments is critical to an understanding of measurement accuracy. We have developed a phase-plane behavioral model, implemented it in SIMULINK and applied it to interleaved, high-speed ADCs (up to 4 gigasamples/sec). We have also developed and demonstrated techniques to effectively compensate for these impairments based upon the model.
Date: April 4, 2005
Creator: Fong, P; Teruya, A & Lowry, M
System: The UNT Digital Library
K0(s) and Lambda0 production studies in p anti-p collisions at s**(1/2) = 1800 and 630-GeV (open access)

K0(s) and Lambda0 production studies in p anti-p collisions at s**(1/2) = 1800 and 630-GeV

The authors present a study of the production of K{sub s}{sup 0} and {Lambda}{sup 0} in inelastic p{bar p} collisions at {radical}s = 1800 and 630 GeV using data collected by the CDF experiment at the Fermilab Tevatron. Analyses of K{sub s}{sup 0} and {Lambda}{sup 0} multiplicity and transverse momentum distributions, as well as of the dependencies of the average number and (p{sub T}) of K{sub s}{sup 0} and {Lambda}{sup 0} on charged particle multiplicity are reported. Systematic comparisons are performed for the full sample of inelastic collisions, and for the low and high momentum transfer subsamples, at the two energies. The p{sub T} distributions extend above 8 GeV/c, showing a (p{sub T}) higher than previous measurements. The dependence of the mean K{sub s}{sup 0}({Lambda}{sup 0}) p{sub T} on the charged particle multiplicity for the three samples shows a behavior analogous to that of charged primary tracks.
Date: April 1, 2005
Creator: Acosta, D.; Affolder, Anthony A.; Albrow, M. G.; Ambrose, D.; Amidei, D.; Anikeev, K. et al.
System: The UNT Digital Library
Background reduction in cryogenic detectors (open access)

Background reduction in cryogenic detectors

This paper discusses the background reduction and rejection strategy of the Cryogenic Dark Matter Search (CDMS) experiment. Recent measurements of background levels from CDMS II at Soudan are presented, along with estimates for future improvements in sensitivity expected for a proposed SuperCDMS experiment at SNOLAB.
Date: April 1, 2005
Creator: Bauer, Daniel A.
System: The UNT Digital Library
QCD FACTORIZATION FOR SEMI-INCLUSIVE DEEP INELASTIC SCATTERING. (open access)

QCD FACTORIZATION FOR SEMI-INCLUSIVE DEEP INELASTIC SCATTERING.

In this talk, we will present a QCD factorization theorem for the semi-inclusive deep-inelastic scattering with hadrons in the current fragmentation region detected at low transverse momentum.
Date: April 27, 2005
Creator: YUAN, F.
System: The UNT Digital Library
Stability of barrier buckets with short barrier separations (open access)

Stability of barrier buckets with short barrier separations

A barrier bucket with very short or zero rf-barrier separation (relative to the barrier widths) has its synchrotron tune decreasing from a very large value towards the bucket boundary. As a result, chaotic region may form near the bucket center and extends outward under increasing modulation of rf voltage and/or rf phase. Application is made to those barrier buckets used in momentum mining at the Fermilab Recycler Ring.
Date: April 1, 2005
Creator: Ng, K. Y.
System: The UNT Digital Library
FROM THE ISR TO RHIC - MEASUREMENTS OF HARD-SCATTERING AND JETS USING INCLUSIVE SINGLE PARTICLE PRODUCTION AND 2-PARTICLE CORRELATIONS. (open access)

FROM THE ISR TO RHIC - MEASUREMENTS OF HARD-SCATTERING AND JETS USING INCLUSIVE SINGLE PARTICLE PRODUCTION AND 2-PARTICLE CORRELATIONS.

Hard scattering in p-p collisions, discovered at the CERN ISR in 1972 by the method of leading particles, proved that the partons of Deeply Inelastic Scattering strongly interacted with each other. Further ISR measurements utilizing inclusive single or pairs of hadrons established that high p{sub T} particles are produced from states with two roughly back-to-back jets which are the result of scattering of constituents of the nucleons as described by Quantum Chromodynamics (QCD), which was developed during the course of these measurements. These techniques, which are the only practical method to study hard-scattering and jet phenomena in Au+Au central collisions at RHIC energies, are reviewed, as an introduction to present RHIC measurements.
Date: April 23, 2005
Creator: Tannenbaum, M. J.
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