Resource Type

Language

Radiation-driven evolution of low-mass x-ray binaries and the formation of millisecond pulsars (open access)

Radiation-driven evolution of low-mass x-ray binaries and the formation of millisecond pulsars

Recent data on low-mass X-ray binaries (LMXBs) and millisecond pulsars (MSPs) pose a challenge to evolutionary theories which neglect the effects of disk and comparison irradiation. Here we discuss the main features of a radiation-driven (RD) evolutionary model that may be applicable to several LMXBs. According to this model, radiation from the accreting compact star in LMXBs vaporizes'' the accretion disk and the companion star by driving a self-sustained mass loss until a sudden accretion-turn off occurs. The main characteristics of the RD-evolution are: (1) lifetime of RD-LMXB's is of order 10{sup 7} years or less; (2) both the orbital period gap and the X-ray luminosity may be consequences of RD-evolution of LMXB's containing lower main sequence and degeneration companion stars; (3) the companion star may transfer mass to the primary even if it underfills its Roche lobe; (4) a class of recycled MSPs can continue to vaporize the low-mass companions by a strong pulsar wind even after the accretion turn-off; (5) the RD-evolutionary model resolves the apparent statistical descrepancy between the number of MSPs and their LMXB progenitors in the Galaxy. We discuss the implications of the discovery of single MSPs in low-density globular clusters and the recent measurements …
Date: August 8, 1991
Creator: Tavani, M. (Lawrence Livermore National Lab., CA (United States) California Univ., Berkeley, CA (United States). Dept. of Astronomy)
System: The UNT Digital Library
Probing Late Neutrino Mass Properties With SupernovaNeutrinos (open access)

Probing Late Neutrino Mass Properties With SupernovaNeutrinos

Models of late-time neutrino mass generation contain new interactions of the cosmic background neutrinos with supernova relic neutrinos (SRNs). Exchange of an on-shell light scalar may lead to significant modification of the differential SRN flux observed at earth. We consider an Abelian U(1) model for generating neutrino masses at low scales, and show that there are cases for which the changes induced in the flux allow one to distinguish the Majorana or Dirac nature of neutrinos, as well as the type of neutrino mass hierarchy (normal or inverted or quasi-degenerate). In some region of parameter space the determination of the absolute values of the neutrino masses is also conceivable. Measurements of the presence of these effects may be possible at the next-generation water Cerenkov detectors enriched with Gadolinium, or a 100 kton liquid argon detector.
Date: August 8, 2007
Creator: Baker, Joseph; Goldberg, Haim; Perez, Gilad & Sarcevic, Ina
System: The UNT Digital Library
The Genome of the Epsilonproteobacterial Chemolithoautotroph Sulfurimonas dentrificans (open access)

The Genome of the Epsilonproteobacterial Chemolithoautotroph Sulfurimonas dentrificans

Sulfur-oxidizing epsilonproteobacteria are common in a variety of sulfidogenic environments. These autotrophic and mixotrophic sulfur-oxidizing bacteria are believed to contribute substantially to the oxidative portion of the global sulfur cycle. In order to better understand the ecology and roles of sulfur-oxidizing epsilonproteobacteria, in particular those of the widespread genus Sulfurimonas, in biogeochemical cycles, the genome of Sulfurimonas denitrificans DSM1251 was sequenced. This genome has many features, including a larger size (2.2 Mbp), that suggest a greater degree of metabolic versatility or responsiveness to the environment than seen for most of the other sequenced epsilonproteobacteria. A branched electron transport chain is apparent, with genes encoding complexes for the oxidation of hydrogen, reduced sulfur compounds, and formate and the reduction of nitrate and oxygen. Genes are present for a complete, autotrophic reductive citric acid cycle. Many genes are present that could facilitate growth in the spatially and temporally heterogeneous sediment habitat from where Sulfurimonas denitrificans was originally isolated. Many resistance-nodulation-development family transporter genes (10 total) are present; of these, several are predicted to encode heavy metal efflux transporters. An elaborate arsenal of sensory and regulatory protein-encoding genes is in place, as are genes necessary to prevent and respond to oxidative stress.
Date: August 8, 2007
Creator: Class, USF Genomics; Sievert, Stefan M.; Scott, Kathleen M.; Klotz, Martin G.; Chain, Patrick S.G.; Hauser, Loren J. et al.
System: The UNT Digital Library
Design and Construction of Test Coils for the MICE Coupling Solenoid Magnet (open access)

Design and Construction of Test Coils for the MICE Coupling Solenoid Magnet

The superconducting coupling solenoid to be applied in the Muon Ionization Cooling Experiment (MICE) is made from copper matrix Nb-Ti conductors with inner radius of 750 mm, length of 285 mm and thickness of 102.5 mm at room temperature. The magnetic field up to 2.6 T at the magnet centerline is to keep the muons within the MICE RF cavities. Its self inductance is around 592 H and its magnet stored energy is about 13 MJ at a full current of 210 A for the worst operation case of the MICE channel. The stress induced inside the coil during cool down and charging is relatively high. Two test coils are to build and test in order to validate the design method and develop the fabrication technique required for the coupling coil winding, one is 350 mm inner diameter and full length same as the coupling coil, and the other is one-quarter length and 1.5 m diameter. The 1.5 m diameter coil will be charged to strain conditions that are greater than would be encountered in the coupling coil. This paper presents detailed design of the test coils as well as developed winding skills. The analyses on stress in coil assemblies, …
Date: August 8, 2008
Creator: Wang, Li; Pan, Heng; Xu, F.Y.; Liu, XioaKun; Chen, AnBin; Li, LanKai et al.
System: The UNT Digital Library
Use of Conducting Polymers for Electronic Communication with Redox Active Nanoparticles (open access)

Use of Conducting Polymers for Electronic Communication with Redox Active Nanoparticles

Nanoscale materials provide unique properties that will enable new technologies and enhance older ones. One area of intense activity in which nanoscale materials are being used is in the development of new functional materials for battery applications.1-4 This effort promises superior materials with properties that circumvent many of the problems associated with traditional battery materials. Previously we have worked on several approaches for using nanoscale materials for application as cathode materials in rechargeable Li batteries.5-11 Our recent work has focused on synthesizing MnO2 nanoparticles and using conducting polymers to electronically address these particles in nanoparticle assemblies. This presentation will focus on those efforts. MnO2 nanoparticles that are encapsulated with poly(3,4-ethylenedioxythiophene) (PEDOT) are prepared using 3,4-ethylenedioxythiophene (EDOT) as a chemical reductant for permanganate anion. This non-aqueous preparation is based on a recent report of a similar method for preparation of PEDOT-encapsulated Au nanoparticles.12 We also describe the synthesis of MnO2 colloidal nanoparticles prepared using an aqueous route involving reduction of permanganate anion with butanol using a previously described route.13 We report the synthesis and characterization of the PEDOT material, and the aqueous colloidal material. We show that the aqueous colloidal nanoparticles can be trapped in thin films using a layer-by-layer deposition …
Date: August 8, 2004
Creator: Bazito, Fernanda; O'Brien, Robert & Buttry, Daniel A.
System: The UNT Digital Library
Simple Stringy Dynamical SUSY Breaking (open access)

Simple Stringy Dynamical SUSY Breaking

We present simple string models which dynamically break supersymmetry without non-Abelian gauge dynamics. The Fayet model, the Polonyi model, and the O'Raifeartaigh model each arise from D-branes at a specific type of singularity. D-brane instanton effects generate the requisite exponentially small scale of supersymmetry breaking.
Date: August 8, 2007
Creator: Aharony, Ofer; /Weizmann Inst. /Stanford U., Phys. Dept. /SLAC; Kachru, Shamit; Silverstein, Eva & /Stanford U., Phys. Dept. /SLAC
System: The UNT Digital Library
VERIFICATION TEST PROBLEMS (open access)

VERIFICATION TEST PROBLEMS

We present analytic solutions to two test problems that can be used to check the hydrodynamic implementation in computer codes designed to calculate the propagation of shocks in spherically convergent geometry. Our analysis is restricted to fluid materials with constant bulk modulus. In the first problem we present the exact initial acceleration and pressure gradient at the outer surface of a sphere subjected to an exponentially decaying pressure of the form P(t) = P{sub 0}e{sup -at}. We show that finely-zoned hydro-code simulations are in good agreement with our analytic solution. In the second problem we discuss the implosions of incompressible spherical fluid shells and we present the radial pressure profile across the shell thickness. We also discuss a semi-analytic solution to the time-evolution of a nearly spherical shell with arbitrary but small initial 3-dimensional (3-D) perturbations on its inner and outer surfaces.
Date: August 8, 2007
Creator: Moran, B
System: The UNT Digital Library
Dislocation nucleation in bcc Ta single crystals studied by nanoindentation (open access)

Dislocation nucleation in bcc Ta single crystals studied by nanoindentation

The study of dislocation nucleation in closed-packed metals by nanoindentation has recently attracted much interest. Here, we address the peculiarities of the incipient plasticity in body centered cubic (bcc) metals using low index Ta single-crystals as a model system. The combination of nanoindentation with high-resolution atomic force microscopy provides us with experimental atomic-scale information on the process of dislocation nucleation and multiplication. Our results reveal a unique deformation behavior of bcc Ta at the onset of plasticity which is distinctly different from that of closed-packed metals. Most noticeable, we observe only one rather than a sequence of discontinuities in the load-displacement curves. This and other differences are discussed in context of the characteristic plastic deformation behavior of bcc metals.
Date: August 8, 2007
Creator: Biener, M M; Biener, J; Hodge, A M & Hamza, A V
System: The UNT Digital Library
Nuclear diffractive structure functions at high energies (open access)

Nuclear diffractive structure functions at high energies

A future high-energy electron-ion collider would explore the non-linear weakly-coupled regime of QCD, and test the Color Glass Condensate (CGC) approach to high-energy scattering. Hard diffraction in deep inelastic scattering off nuclei will provide many fundamental measurements. In this work, the nuclear diffractive structure function F{sub 2,A}{sup D} is predicted in the CGC framework, and the features of nuclear enhancement and suppression are discussed.
Date: August 8, 2008
Creator: Marquet,C.; Kowalski, H.; Lappi, T. & Venugopalan, R.
System: The UNT Digital Library
A Molecular Assessment of Phylogenetic Relationships and LineageDiversification Within the Family Salamandridae (Amphibia, Caudata) (open access)

A Molecular Assessment of Phylogenetic Relationships and LineageDiversification Within the Family Salamandridae (Amphibia, Caudata)

Phylogenetic relationships among species of the salamanderfamily Salamandridae are investigated using nearly 3000 nucleotide basesof newly reported mitochondrial DNA sequence data from the mtDNA genicregion spanning the genes tRNALeu-COI. This study uses nearlycomprehensive species-level sampling to provide the first completephylogeny for the Salamandridae. Deep phylogenetic relationships amongthe three most divergent lineages in the family Salamandrina terdigitata,a clade comprising the "True" salamanders, and a clade comprising allnewts except S. terdigitata are difficult to resolve. However, mostrelationships within the latter two lineages are resolved with robustlevels of branch support. The genera Euproctus and Triturus arestatistically shown to be nonmonophyletic, instead each contains adiverse set of lineages positioned within the large newt clade. The genusParamesotriton is also resolve as a nonmonophyletic group, with the newlydescribed species P. laoensis constituting a divergent lineage placed ina sister position to clade containing all Pachytriton species and allremaining Paramesotriton species. Sequence divergences between P.laoensis and other Paramesotriton species are as great as those comparingP. laoensis and species of the genera Cynops and Pachytriton. Analyses oflineage diversification across the Salamandridae indicate that, despiteits exceptional diversity, lineage accumulation appears to have beenconstant across time, indicating that it does not represent a truespecies radiation.
Date: August 8, 2005
Creator: Weisrock, David W.; Papenfuss, Theodore J.; Macey, J. Robert; Litvinchuk, Spartak N.; Polymeni, Rosa; Ugurtas, Ismail H. et al.
System: The UNT Digital Library
The characterization of Nb/sub 3/Sn superconductors for use in magnets of 19 T and greater (open access)

The characterization of Nb/sub 3/Sn superconductors for use in magnets of 19 T and greater

Increased resolution of NMR spectrometry will require the use of very high field Nb/sub 3/Sn superconducting magnets. Here we report the results of our investigation into mechanical and temperature effects on internal-Sn superconductors similar to those proposed for use in a 900 MHz, 21 T NMR magnet system. Thermal precompression was found to be about 0.225%, and the irreversible strain was about 0.8%. Fatigue degradation was not observed at cyclic intrinsic strains below 0.575%. Additions of reinforcing steel in cable conductors was found to reduce the critical current by as much as 50% compared to similar, unreinforced cables. Reduction of the testing temperature to 2.3 K did not increase the critical current in steel-reinforced cables to a level significantly above that of unreinforced samples. 4 refs., 3 figs., 1 tab.
Date: August 8, 1989
Creator: Summers, L. T.; Strum, M. J. & Miller, J. R.
System: The UNT Digital Library
The International Thermonuclear Experimental Reactor (ITER): Design and materials selection (open access)

The International Thermonuclear Experimental Reactor (ITER): Design and materials selection

The success of ITER relies on aggressive design of the superconducting magnet systems. This design emphasized high radiation-damage tolerance, acceptance of high nuclear heat loads, and high operational stresses in the Toroidal Field (TF) magnets. The design of the Central Solenoid (CS) magnets, although they will be well shielded from the plasma, is equally aggressive due to the need for very high magnetic fields (14 T) and long term operation at high cyclic stresses. Success of these magnet designs depends, in part, on sound selection and fabrication of materials for structural, superconducting, and insulating components. Here we review the design of ITER and the selection of structural materials for some of the systems that will operate at cryogenic temperatures. In addition we will introduce some of the data that the materials selection is based on and suggest opportunities for future research in support of ITER. 10 refs., 1 fig., 4 tabs.
Date: August 8, 1989
Creator: Summers, L. T.; Miller, J. R. & Heim, J. R.
System: The UNT Digital Library
Advanced high-field coil designs: 20 TESLA (open access)

Advanced high-field coil designs: 20 TESLA

This study of the technology required for producing large high-field coils has shown that, with some extensions to our present technological base, feasible designs are achievable. The resulting magnets could well make a paramount contribution to the national mirror-fusion endeavor.
Date: August 8, 1983
Creator: Hoard, R. W.; Cornish, D. N.; Scanlan, R. M.; Zbasnik, J. P.; Leber, R. L.; Hickman, R. B. et al.
System: The UNT Digital Library
Decommissioning a tritium glove-box facility (open access)

Decommissioning a tritium glove-box facility

A large glove-box facility for handling reactive metal tritides was decommissioned. Major sections of the glove box were decontaminated and disassembled for reuse at another tritium facility. To achieve the desired results, decontamnation required repeated washing, first with organic liquids, then with water and detergents. Worker protection was provided by simple ventilation combined with careful monitoring of the work areas and employees. Several innovative techniques are described.
Date: August 8, 1979
Creator: Folkers, C. L.; Homann, S. G.; Nicolosi, A. S.; Hanel, S. L. & King, W. C.
System: The UNT Digital Library
High performance inertial fusion targets (open access)

High performance inertial fusion targets

Inertial confinement fusion (ICF) target designs are considered which may have very high gains (approximately 1000) and low power requirements (< 100 TW) for input energies of approximately one megajoule. These include targets having very low density shells, ultra thin shells, central ignitors, magnetic insulation, and non-ablative acceleration.
Date: August 8, 1978
Creator: Nuckolls, J.H.; Bangerter, R.O.; Lindl, J.D.; Mead, W.C. & Pan, Y.L.
System: The UNT Digital Library
The records management challenge (open access)

The records management challenge

None
Date: August 8, 1990
Creator: Zeile, H. J.
System: The UNT Digital Library
X-ray diffractometry of lanthanum-nickel-aluminum alloys. Part 1 (open access)

X-ray diffractometry of lanthanum-nickel-aluminum alloys. Part 1

X-ray diffractometry provides much useful information on LANA alloys that complements data obtained by SEM and Electron Microprobe Analysis. Accurate measurements of the hexagonal lattice parameters of the primary LaNi{sub 5-y}Aly phase reveal the aluminum content (y) and allow the prediction of desorption pressures for the hydrogen isotopes. A study of the broadening of x-ray diffraction lines of the LaNi{sub 5-y}Aly primary phase caused by cyclic absorption and desorption of hydrogen suggests that substitution of aluminum for nickel stabilizes the primary phase with respect to formation of antistructure defects that could cause undesirable trapping of hydrogen isotopes. Correlation of XRD with SEM and EMPA results has helped identify secondary phases, determine their abundances in volume percent, and reveal how they react with hydrogen and the atmosphere. Characterizations of LANA alloys used in process development has provided the bases for development of specifications for alloys to be used in the Replacement Trittium Facility. 28 refs., 4 tabs., 12 figs.
Date: August 8, 1988
Creator: Mosley, W. C.
System: The UNT Digital Library
Realizing parallel reduction operation in Sisal 1.2. Revision 1 (open access)

Realizing parallel reduction operation in Sisal 1.2. Revision 1

Often the tasks of a parallel job compute sets of values that are reduced to a single value or gathered to build an aggregate structure. Since reductions may introduce dependencies, most languages separate computation and reduction. For example, Fortran 90 and HPF provide a rich set of predefined reduction functions but only for extant arrays. Sisal 1.2 is unique in that it supports seven reduction operations as a natural consequence of loop expressions. These reductions are limited and cannot express the variety of reduction operations found in parallel programs. In this paper, the authors present compilation techniques that recognize pairs of computation-reduction expressions in Sisal 1.2 and fuse them into single parallel loops. This optimization overlaps computation and reduction, reduces runtime overhead, and reduces storage requirements. They describe an implementation and they present performance numbers that demonstrate the utility of their techniques.
Date: August 8, 1994
Creator: Denton, S. M.; Feo, J. T. & Miller, P. J.
System: The UNT Digital Library
Demonstration of zinc/air fuel battery to enhance the range and mission of fleet electric vehicles: Preliminary results in the refueling of a multicell module (open access)

Demonstration of zinc/air fuel battery to enhance the range and mission of fleet electric vehicles: Preliminary results in the refueling of a multicell module

We report progress in an effort to develop and demonstrate a refuelable zinc/air battery for fleet electric vehicle applications. A refuelable module consisting of twelve bipolar cells with internal flow system has been refueled at rates of nearly 4 cells per minute refueling time of 10 minutes for a 15 kW, 55 kWh battery. The module is refueled by entrainment of 0.5-mm particles in rapidly flowing electrolyte, which delivers the particles into hoppers above each cell in a parallel-flow hydraulic circuit. The concept of user-recovery is presented as an alternative to centralized service infrastructure during market entry.
Date: August 8, 1994
Creator: Cooper, J. F.; Fleming, D.; Keene, L.; Maimoni, A.; Peterman, K. & Koopman, R.
System: The UNT Digital Library
IUPAC Statues and Bylaws. (open access)

IUPAC Statues and Bylaws.

From the history of the Commission, it began with a large number of members. It was found that it was difficult to gain agreement by correspondence between such a large group. A smaller group was elected to operate by correspondence and make decisions. It operated successfully for a half century in this manner. With funding available, the Commission membership grew larger but they.discussed all matters face to face at Commission meetings. Subcommittees were appointed to pursue specialized topics and members reported and discussed their subcommittee results directly to the Commission at the face to face meetings. With the change in the bylaws, future face to face meetings will no longer be an option for the members of the Commission and its subcommittees, unless all members provide their own funds or those of their host institutions. The funding and membership restrictions are all serious topics, which require a thorough discussion.
Date: August 8, 2003
Creator: Holden, Norman E.
System: The UNT Digital Library
Chemistry at Extreme Conditions (open access)

Chemistry at Extreme Conditions

We present equation of state results from impulsively stimulated light scattering (ISLS) experiments conducted in diamond anvil cells on pure supercritical fluids. We have made measurements on fluid H{sub 2}O (water), and CH{sub 3}OH (methanol). Sound speeds measured through ISLS have allowed us to refine existing potential models used in the exponential-6 (EXP-6) detonation product library [Fried, L. E., and Howard, W. M., J. Chem. Phys. 109 (17): 7338-7348 (1998).]. The refined models allow us to more accurately assess the chemical composition at the Chapman-Jouget (C-J) state of common energetic materials. We predict that water is present in appreciable quantities at the C-J state of energetic materials HMX, RDX, and nitro methane.
Date: August 8, 2002
Creator: Zaug, J M; Fried, L E; Abramson, E H; Hansen, D W; Crowhurst, J C & Howard, W M
System: The UNT Digital Library
Positivity Preservation and Advection Algorithm Tests for Edge Plasma Turbulence (open access)

Positivity Preservation and Advection Algorithm Tests for Edge Plasma Turbulence

None
Date: August 8, 2012
Creator: Peterson, J L & Hammett, G W
System: The UNT Digital Library
A Compact UV Timing Fiducial System for use with x-Ray Streak Cameras at NIF (open access)

A Compact UV Timing Fiducial System for use with x-Ray Streak Cameras at NIF

None
Date: August 8, 2012
Creator: Homoelle, D.; Bowers, M.; Browning, D.; Burns, S.; Golick, B.; Erbert, G. et al.
System: The UNT Digital Library
Itinerant and localized magnetic moments in ferrimagnetic Mn{sub 2}CoGa thin films identified with x-ray magnetic linear dichroism: experiment and ab initio theory (open access)

Itinerant and localized magnetic moments in ferrimagnetic Mn{sub 2}CoGa thin films identified with x-ray magnetic linear dichroism: experiment and ab initio theory

Epitaxial thin films of the half-metallic X{sub a}-compound Mn{sub 2}CoGa (Hg{sub 2}CuTi prototype) were prepared by dc magnetron co-sputtering with different heat treatments on MgO (001) substrates. High-quality #12;lms with a bulk magnetization of 1.95(5) {mu}{sub #22;}B per unit cell were obtained. The average Mn magnetic moment and the Co moment are parallel, in agreement with theory. The x-ray magnetic circular dichroism spectra agree with calculations based on density functional theory and reveal the antiparallel alignment of the two inequivalent Mn moments. X-ray magnetic linear dichroism allows to distinguish between itinerant and localized Mn moments. It is shown that one of the two Mn moments has localized character, whereas the other Mn moment and the Co moment are itinerant.
Date: August 8, 2011
Creator: Meinert, Markus; Schmalhorst, Jan-Michael; Klewe, Cristoph; Reiss, Gunter; Arenholz, Elke; Bohnert, Tim et al.
System: The UNT Digital Library