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A Test of HTS Power Cable in a Sweeping Magnetic Field (open access)

A Test of HTS Power Cable in a Sweeping Magnetic Field

Short sample HTS power cable composed of multiple 344C-2G strands and designed to energize a fast-cycling dipole magnet was exposed to a sweeping magnetic field in the (2-20) T/s ramping rate. The B-field orientation toward the HTS strands wide surface was varied from 0{sup 0} to 10{sup 0}, in steps of 1{sup 0}. The test arrangement allowed measurement of the combined hysteresis and eddy current power losses. For the validity of these measurements, the power losses of a short sample cable composed of multiple LTS wire strands were also performed to compare with the known data. The test arrangement of the power cable is described, and the test results are compared with the projections for the eddy and hysteresis power losses using the fine details of the test cable structures.
Date: November 29, 2011
Creator: Piekarz, H.; Hays, S.; Blowers, J. & Shiltsev, V.
System: The UNT Digital Library
Smoothed Aggregation Spectral Element Agglomeration AMG: SA-pAMGe (open access)

Smoothed Aggregation Spectral Element Agglomeration AMG: SA-pAMGe

None
Date: June 29, 2011
Creator: Brezina, M & Vassilevski, P S
System: The UNT Digital Library
Simulation of Prompt Emission from GRBs with a Photospheric Component and its Detectability By GLAST (open access)

Simulation of Prompt Emission from GRBs with a Photospheric Component and its Detectability By GLAST

The prompt emission from gamma-ray bursts (GRBs) still requires a physical explanation. Studies of time-resolved GRB spectra, observed in the keV-MeV range, show that a hybrid model consisting of two components, a photospheric and a non-thermal component, in many cases fits bright, single-pulsed bursts as well as, and in some instances even better than, the Band function. With an energy coverage from 8 keV up to 300 GeV, GLAST will give us an unprecedented opportunity to further investigate the nature of the prompt emission. In particular, it will give us the possibility to determine whether a photospheric component is the determining feature of the spectrum or not. Here we present a short study of the ability of GLAST to detect such a photospheric component in the sub-MeV range for typical bursts, using simulation tools developed within the GLAST science collaboration.
Date: November 29, 2011
Creator: Battelino, Milan; Ryde, Felix; Observ., /Stockholm; Omodei, Nicola; /INFN, Pisa; Longo, Francesco et al.
System: The UNT Digital Library
Massive Stars in Colliding Wind Systems: the GLAST Perspective (open access)

Massive Stars in Colliding Wind Systems: the GLAST Perspective

Colliding winds of massive stars in binary systems are considered as candidate sites of high-energy non-thermal photon emission. They are already among the suggested counterparts for a few individual unidentified EGRET sources, but may constitute a detectable source population for the GLAST observatory. The present work investigates such population study of massive colliding wind systems at high-energy gamma-rays. Based on the recent detailed model (Reimer et al. 2006) for non-thermal photon production in prime candidate systems, we unveil the expected characteristics of this source class in the observables accessible at LAT energies. Combining the broadband emission model with the presently cataloged distribution of such systems and their individual parameters allows us to conclude on the expected maximum number of LAT-detections among massive stars in colliding wind binary systems.
Date: November 29, 2011
Creator: Reimer, Anita; Reimer, Olaf & /Stanford U., HEPL /KIPAC, Menlo Park
System: The UNT Digital Library
Propagation of rarefaction pulses in particulate materials with strain-softening behavior (open access)

Propagation of rarefaction pulses in particulate materials with strain-softening behavior

We investigate rarefaction waves in nonlinear periodic systems with a 'softening' power-law relationship between force and displacement to understand the dynamic behavior of this class of materials. A closed form expression describing the shape of the strongly nonlinear rarefaction wave is exact for n = 1/2 and agrees well with the shape and width of the pulses resulting from discrete simulations. A chain of particles under impact was shown to propagate a rarefaction pulse as the leading pulse in initially compressive impulsive loading in the absence of dissipation. Compression pulses generated by impact quickly disintegrated into a leading rarefaction solitary wave followed by an oscillatory train. Such behavior is favorable for metamaterials design of shock absorption layers as well as tunable information transmission lines for scrambling of acoustic information.
Date: July 29, 2011
Creator: Herbold, E B & Nesterenko, V F
System: The UNT Digital Library
GLAMM: Genome-Linked Application for Metabolic Maps (open access)

GLAMM: Genome-Linked Application for Metabolic Maps

The Genome-Linked Application for Metabolic Maps (GLAMM) is a unified web interface for visualizing metabolic networks, reconstructing metabolic networks from annotated genome data, visualizing experimental data in the context of metabolic networks, and investigating the construction of novel, transgenic pathways. This simple, user-friendly interface is tightly integrated with the comparative genomics tools of MicrobesOnline. GLAMM is available for free to the scientific community at glamm.lbl.gov.
Date: May 29, 2011
Creator: Bates, John; Chivian, Dylan & Arkin, Adam
System: The UNT Digital Library
Calibration of the GLAST Burst Monitor Detectors (open access)

Calibration of the GLAST Burst Monitor Detectors

The GLAST Burst Monitor (GBM) will augment the capabilities of GLAST for the detection of cosmic gamma-ray bursts by extending the energy range (20 MeV to > 300 GeV) of the Large Area Telescope (LAT) towards lower energies by 2 BGO-detectors (150 keV to 30 MeV) and 12 NaI(Tl) detectors (10 keV to 1 MeV). The physical detector response of the GBM instrument for GRBs is determined with the help of Monte Carlo simulations, which are supported and verified by on-ground calibration measurements, performed extensively with the individual detectors at the MPE in 2005. All flight and spare detectors were irradiated with calibrated radioactive sources in the laboratory (from 14 keV to 4.43 MeV). The energy/channel-relations, the dependences of energy resolution and effective areas on the energy and the angular responses were measured. Due to the low number of emission lines of radioactive sources below 100 keV, calibration measurements in the energy range from 10 keV to 60 keV were performed with the X-ray radiometry working group of the Physikalisch-Technische Bundesanstalt (PTB) at the BESSY synchrotron radiation facility, Berlin.
Date: November 29, 2011
Creator: von Kienlin, Andreas; Bissaldi, Elisabetta; Lichti, Giselher G.; Steinle, Helmut; Krumrey, Michael; Gerlach, Martin et al.
System: The UNT Digital Library
A Nanocrystal Sensor for Luminescence Detection of Cellular Forces (open access)

A Nanocrystal Sensor for Luminescence Detection of Cellular Forces

Quantum dots have been used as bright fluorescent tags with high photostability to probe numerous biological systems. In this work we present the tetrapod quantum dot as a dynamic, next-generation nanocrystal probe that fluorescently reports cellular forces with spatial and temporal resolution. Its small size and colloidal state suggest that the tetrapod may be further developed as a tool to measure cellular forces in vivo and with macromolecular spatial resolution.
Date: September 29, 2011
Creator: Choi, Charina; Chou, Jonathan; Lutker, Katie; Werb, Zena & Alivisatos, Paul
System: The UNT Digital Library
FastQuery: A Parallel Indexing System for Scientific Data (open access)

FastQuery: A Parallel Indexing System for Scientific Data

Modern scientific datasets present numerous data management and analysis challenges. State-of-the- art index and query technologies such as FastBit can significantly improve accesses to these datasets by augmenting the user data with indexes and other secondary information. However, a challenge is that the indexes assume the relational data model but the scientific data generally follows the array data model. To match the two data models, we design a generic mapping mechanism and implement an efficient input and output interface for reading and writing the data and their corresponding indexes. To take advantage of the emerging many-core architectures, we also develop a parallel strategy for indexing using threading technology. This approach complements our on-going MPI-based parallelization efforts. We demonstrate the flexibility of our software by applying it to two of the most commonly used scientific data formats, HDF5 and NetCDF. We present two case studies using data from a particle accelerator model and a global climate model. We also conducted a detailed performance study using these scientific datasets. The results show that FastQuery speeds up the query time by a factor of 2.5x to 50x, and it reduces the indexing time by a factor of 16 on 24 cores.
Date: July 29, 2011
Creator: Chou, Jerry; Wu, Kesheng & Prabhat,
System: The UNT Digital Library
MODELING OF LONG-TERM FATE OF MOBILIZED FINES DUE TO DAM-EMBANKMENT INTERFACIAL DISLOCATIONS (open access)

MODELING OF LONG-TERM FATE OF MOBILIZED FINES DUE TO DAM-EMBANKMENT INTERFACIAL DISLOCATIONS

None
Date: July 29, 2011
Creator: Ezzedine, S; Kanarska, Y; Lomov, I; Antoun, T & Glascoe, L
System: The UNT Digital Library
Ferrimagnetism and disorder of epitaxial Mn2-xCoxVAl Heusler compound thin films (open access)

Ferrimagnetism and disorder of epitaxial Mn2-xCoxVAl Heusler compound thin films

The quaternary full Heusler compound Mn{sub 2-x}Co{sub x}VAl with x = 1 is predicted to be a half-metallic antiferromagnet. Thin films of the quaternary compounds with x = 0-2 were prepared by dc and RF magnetron co-sputtering on heated MgO (0 0 1) substrates. The magnetic structure was examined by x-ray magnetic circular dichroism and the chemical disorder was characterized by x-ray diffraction. Ferrimagnetic coupling of V to Mn was observed for Mn{sub 2}VAl (x = 0). For x = 0.5, we also found ferrimagnetic order with V and Co antiparallel to Mn. The observed reduced magnetic moments are interpreted with the help of band structure calculations in the coherent potential approximation. Mn{sub 2}VAl is very sensitive to disorder involving Mn, because nearest-neighbour Mn atoms couple antiferromagnetically. Co{sub 2}VAl has B2 order and has reduced magnetization. In the cases with x {ge} 0.9 conventional ferromagnetism was observed, closely related to the atomic disorder in these compounds.
Date: January 29, 2011
Creator: Meinert, Markus; Schmalhorst, Jan-Michael; Reiss, Gunter & Arenholz, Elke
System: The UNT Digital Library
Fermi/LAT Discovery of Gamma-Ray Emission From a Relativistic Jet in the Narrow-Line Quasar PMN J0948+0022 (open access)

Fermi/LAT Discovery of Gamma-Ray Emission From a Relativistic Jet in the Narrow-Line Quasar PMN J0948+0022

None
Date: November 29, 2011
Creator: Abdo, Aous A.; Ackermann, M.; Ajello, Marco; Axelsson, M.; Baldini, L.; Ballet, J. et al.
System: The UNT Digital Library
Supernova Remnants And GLAST (open access)

Supernova Remnants And GLAST

It has long been speculated that supernova remnants represent a major source of cosmic rays in the Galaxy. Observations over the past decade have ceremoniously unveiled direct evidence of particle acceleration in SNRs to energies approaching the knee of the cosmic ray spectrum. Nonthermal X-ray emission from shell-type SNRs reveals multi-TeV electrons, and the dynamical properties of several SNRs point to efficient acceleration of ions. Observations of TeV gamma-ray emission have confirmed the presence of energetic particles in several remnants as well, but there remains considerable debate as to whether this emission originates with high energy electrons or ions. Equally uncertain are the exact conditions that lead to efficient particle acceleration. Based on the catalog of EGRET sources, we know that there is a large population of Galactic gamma-ray sources whose distribution is similar to that of SNRs.With the increased resolution and sensitivity of GLAST, the gamma-ray SNRs from this population will be identified. Their detailed emission structure, along with their spectra, will provide the link between their environments and their spectra in other wavebands to constrain emission models and to potentially identify direct evidence of ion acceleration in SNRs. Here I summarize recent observational and theoretical work in the …
Date: November 29, 2011
Creator: Slane, Patrick & Astrophys., /Harvard-Smithsonian Ctr.
System: The UNT Digital Library
Integrated genomic and transcriptomic analysis reveals mycoparasitism as the ancestoral life style of Trichoderma (open access)

Integrated genomic and transcriptomic analysis reveals mycoparasitism as the ancestoral life style of Trichoderma

Mycoparasitism, a lifestyle where one fungus is parasitic on another fungus has special relevance when the prey is a plant pathogen, providing a strategy for biological control of pests for plant protection. Probably, the most studied biocontrol agents are species of the genus Hypocrea/Trichoderma.
Date: April 29, 2011
Creator: Kubicek, Christian P.; Herrera-Estrella, Alfredo; Seidl, Verena; Le Crom, Stéphane; Martinez, Diego A.; Druzhinina, Irina S. et al.
System: The UNT Digital Library
Runtime Detection of C-Style Errors in UPC Code (open access)

Runtime Detection of C-Style Errors in UPC Code

Unified Parallel C (UPC) extends the C programming language (ISO C 99) with explicit parallel programming support for the partitioned global address space (PGAS), which provides a global memory space with localized partitions to each thread. Like its ancestor C, UPC is a low-level language that emphasizes code efficiency over safety. The absence of dynamic (and static) safety checks allows programmer oversights and software flaws that can be hard to spot. In this paper, we present an extension of a dynamic analysis tool, ROSE-Code Instrumentation and Runtime Monitor (ROSECIRM), for UPC to help programmers find C-style errors involving the global address space. Built on top of the ROSE source-to-source compiler infrastructure, the tool instruments source files with code that monitors operations and keeps track of changes to the system state. The resulting code is linked to a runtime monitor that observes the program execution and finds software defects. We describe the extensions to ROSE-CIRM that were necessary to support UPC. We discuss complications that arise from parallel code and our solutions. We test ROSE-CIRM against a runtime error detection test suite, and present performance results obtained from running error-free codes. ROSE-CIRM is released as part of the ROSE compiler under …
Date: September 29, 2011
Creator: Pirkelbauer, P; Liao, C; Panas, T & Quinlan, D
System: The UNT Digital Library
A Single Pulse Sub-Nanosecond Proton RFQ (open access)

A Single Pulse Sub-Nanosecond Proton RFQ

A Radio Frequency Quadrupole (RFQ) linac system has been developed to provide a single pulse of 2 MeV protons with a beam pulse width of {approx}300 ps and a charge of 30 pC, either for injection into a pulsed Dielectric Wall Accelerator or for bombardment of a target to produce a fast neutron pulse. The 1.2 m long RFQ structure operates at 425 MHz and bunches and accelerates a single 2.35 ns beam pulse injected into it at 35 keV using a parallel plate deflector placed directly in front of the RFQ entrance. The input acceptance properties of the RFQ allow a simple dc bias voltage on the plates to block acceleration of the unwanted beam, with a short rf voltage pulse applied to null the deflection field for the ions within the 8 mm 'kicker' plate length. The use of the RFQ as the accelerating structure allows one to efficiently produce a large charge in a single sub-ns bunch. In addition, the kicker can also be used without the dc bias voltage to produce a 'notch' in the normal RFQ output beam for synchrotron injection.
Date: March 29, 2011
Creator: Hamm, R. W.; Pearce-Percy, H.; Pearson, D.; Rougieri, M.; Weir, J.; Zografos, A. et al.
System: The UNT Digital Library
Fast Simulation of Electromagnetic Showers in the ATLAS Calorimeter: Frozen Showers (open access)

Fast Simulation of Electromagnetic Showers in the ATLAS Calorimeter: Frozen Showers

One of the most time consuming process simulating pp interactions in the ATLAS detector at LHC is the simulation of electromagnetic showers in the calorimeter. In order to speed up the event simulation several parametrisation methods are available in ATLAS. In this paper we present a short description of a frozen shower technique, together with some recent benchmarks and comparison with full simulation. An expected high rate of proton-proton collisions in ATLAS detector at LHC requires large samples of simulated events (Monte Carlo) to study various physics processes. A detailed simulation of particle reactions ('full simulation') in the ATLAS detector is based on GEANT4 and is very accurate. However, due to complexity of the detector, high particle multiplicity and GEANT4 itself, the average CPU time spend to simulate typical QCD event in pp collision is 20 or more minutes for modern computers. During detector simulation the largest time is spend in the calorimeters (up to 70%) most of which is required for electromagnetic particles in the electromagnetic (EM) part of the calorimeters. This is the motivation for fast simulation approaches which reduce the simulation time without affecting the accuracy. Several of fast simulation methods available within the ATLAS simulation framework …
Date: November 29, 2011
Creator: Barberio, E.; Boudreau, J.; Butler, B.; Cheung, S. L.; Dell'Acqua, A.; Di Simone, A. et al.
System: The UNT Digital Library
2011 Clusters, Nanocrystals & Nanostructures Gordon Research Conference (open access)

2011 Clusters, Nanocrystals & Nanostructures Gordon Research Conference

Small particles have been at the heart of nanoscience since the birth of the field and now stand ready to make significant contributions to the big challenges of energy, health and sustainability. Atomic clusters show exquisite size-dependent electronic and magnetic properties and offer a new level of control in catalyses, sensors and biochips; functionalised nanocrystals offer remarkable optical properties and diverse applications in electronic devices, solar energy, and therapy. Both areas are complemented by a raft of recent advances in fabrication, characterization, and performance of a diversity of nanomaterials from the single atom level to nanowires, nanodevices, and biologically-inspired nanosystems. The goal of the 2011 Gordon Conference is thus to continue and enhance the interdisciplinary tradition of this series and discuss the most recent advances, fundamental scientific questions, and emerging applications of clusters, nanocrystals, and nanostructures. A single conference covering all aspects of nanoscience from fundamental issues to applications has the potential to create new ideas and stimulate cross fertilization. The meeting will therefore provide a balance among the three sub-components of the conference, true to its title, with a selection of new topics added to reflect rapid advances in the field. The open atmosphere of a Gordon conference, emphasizing …
Date: July 29, 2011
Creator: Wang, Lai-Sheng
System: The UNT Digital Library
FOUR PI CALIBRATION AND MODELING OF A BARE GERMANIUM DETECTOR IN A CYLINDRICAL FIELD SOURCE (open access)

FOUR PI CALIBRATION AND MODELING OF A BARE GERMANIUM DETECTOR IN A CYLINDRICAL FIELD SOURCE

In reference 1 the authors described {gamma}-ray holdup assay of a Mossbauer spectroscopy instrument where they utilized two axial symmetric cylindrical shell acquisitions and two disk source acquisitions to determine Am-241 and Np-237 contamination. The measured contents of the two species were determined using a general detector efficiency calibration taken from a 12-inch point source.2 The authors corrected the raw spectra for container absorption as well as for geometry corrections to transform the calibration curve to the applicable axial symmetric cylindrical source - and disk source - of contamination. The authors derived the geometry corrections with exact calculus that are shown in equations (1) and (2) of our Experimental section. A cylindrical shell (oven source) acquisition configuration is described in reference 3, where the authors disclosed this configuration to gain improved sensitivity for holdup measure of U-235 in a ten-chamber oven. The oven was a piece of process equipment used in the Savannah River Plant M-Area Uranium Fuel Fabrication plant for which a U-235 holdup measurement was necessary for its decontamination and decommissioning in 2003.4 In reference 4 the authors calibrated a bare NaI detector for these U-235 holdup measurements. In references 5 and 6 the authors calibrated a bare …
Date: April 29, 2011
Creator: Dewberry, R. & Young, J.
System: The UNT Digital Library
Simultaneous Radio to (Sub-) Mm-Monitoring of Variability and Spectral Shape Evolution of Potential GLAST Blazars (open access)

Simultaneous Radio to (Sub-) Mm-Monitoring of Variability and Spectral Shape Evolution of Potential GLAST Blazars

The Large Area Telescope (LAT) instrument onboard GLAST offers a tremendous opportunity for future blazar studies. In order to fully benefit from its capabilities and to maximize the scientific return from the LAT, it is of great importance to conduct dedicated multi-frequency monitoring campaigns that will result comprehensive observations. Consequently, we initiated an effort to conduct a GLAST-dedicated, quasi-simultaneous, broad-band flux-density (and polarization) monitoring of potential GLAST blazars with the Effelsberg and OVRO radio telescopes (11 cm to 7mm wavelength). Here, we present a short overview of these activities which will complement the multi-wavelengths activities of the GLAST/LAT collaboration towards the 'low-energy' radio bands. Further we will give a brief outlook including the extension of this coordinated campaign towards higher frequencies and future scientific aims.
Date: November 29, 2011
Creator: Fuhrmann, L.; Zensus, J. A.; Krichbaum, T. P.; Angelakis, E. & Readhead, A. C. S.
System: The UNT Digital Library
Corrigenda: Finite deformation of a pressurized magnetoelastic membrane in a stationary dipole field (open access)

Corrigenda: Finite deformation of a pressurized magnetoelastic membrane in a stationary dipole field

None
Date: April 29, 2011
Creator: Barham, M.; Steigmann, D. J.; McElfresh, M. & Rudd, R. E.
System: The UNT Digital Library
Status and Plans for an SRF Accelerator Test Facility at Fermilab (open access)

Status and Plans for an SRF Accelerator Test Facility at Fermilab

A superconducting RF accelerator test facility is currently under construction at Fermilab. The accelerator will consist of an electron gun, 40 MeV injector, beam acceleration section consisting of 3 TTF-type or ILC-type cryomodules, and multiple downstream beam lines for testing diagnostics and performing beam experiments. With 3 cryomodules installed this facility will initially be capable of generating an 810 MeV electron beam with ILC beam intensity. The facility can accommodate up to 6 cryomodules for a total beam energy of 1.5 GeV. This facility will be used to test SRF cryomodules under high intensity beam conditions, RF power equipment, instrumentation, and LLRF and controls systems for future SRF accelerators such as the ILC and Project-X. This paper describes the current status and overall plans for this facility.
Date: July 29, 2011
Creator: Church, M.; Leibfritz, J. & Nagaitsev, S.
System: The UNT Digital Library
Finding (Or Not) New Gamma-Ray Pulsars with GLAST (open access)

Finding (Or Not) New Gamma-Ray Pulsars with GLAST

Young energetic pulsars will likely be the largest class of Galactic sources observed by GLAST, with many hundreds detected. Many will be unknown as radio pulsars, making pulsation detection dependent on radio and/or x-ray observations or on blind periodicity searches of the gamma-rays. Estimates for the number of pulsars GLAST will detect in blind searches have ranged from tens to many hundreds. I argue that the number will be near the low end of this range, partly due to observations being made in a scanning as opposed to a pointing mode. This paper briefly reviews how blind pulsar searches will be conducted using GLAST, what limits these searches, and how the computations and statistics scale with various parameters.
Date: November 29, 2011
Creator: Ransom, Scott M. & /NRAO, Charlottesville
System: The UNT Digital Library
Parity Violation Constraints Using Cosmic Microwave Background Polarization Spectra from 2006 and 2007 Observations by the QUaD Polarimeter (open access)

Parity Violation Constraints Using Cosmic Microwave Background Polarization Spectra from 2006 and 2007 Observations by the QUaD Polarimeter

None
Date: November 29, 2011
Creator: Wu, E. Y. S.; Ade, P.; Bock, J.; Bowden, M.; Brown, M. L.; Cahill, G. et al.
System: The UNT Digital Library