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MODEL-BASED HYDROACOUSTIC BLOCKAGE ASSESSMENT AND DEVELOPMENT OF AN EXPLOSIVE SOURCE DATABASE (open access)

MODEL-BASED HYDROACOUSTIC BLOCKAGE ASSESSMENT AND DEVELOPMENT OF AN EXPLOSIVE SOURCE DATABASE

We are continuing the development of the Hydroacoustic Blockage Assessment Tool (HABAT) which is designed for use by analysts to predict which hydroacoustic monitoring stations can be used in discrimination analysis for any particular event. The research involves two approaches (1) model-based assessment of blockage, and (2) ground-truth data-based assessment of blockage. The tool presents the analyst with a map of the world, and plots raypath blockages from stations to sources. The analyst inputs source locations and blockage criteria, and the tool returns a list of blockage status from all source locations to all hydroacoustic stations. We are currently using the tool in an assessment of blockage criteria for simple direct-path arrivals. Hydroacoustic data, predominantly from earthquake sources, are read in and assessed for blockage at all available stations. Several measures are taken. First, can the event be observed at a station above background noise? Second, can we establish backazimuth from the station to the source. Third, how large is the decibel drop at one station relative to other stations. These observational results are then compared with model estimates to identify the best set of blockage criteria and used to create a set of blockage maps for each station. The …
Date: July 11, 2005
Creator: Matzel, E; Ramirez, A & Harben, P
System: The UNT Digital Library
Discretizing gravity in warped spacetime (open access)

Discretizing gravity in warped spacetime

We investigate the discretized version of the compact Randall-Sundrum model. By studying the mass eigenstates of the lattice theory, we demonstrate that for warped space, unlike for flat space, the strong coupling scale does not depend on the IR scale and lattice size. However, strong coupling does prevent us from taking the continuum limit of the lattice theory. Nonetheless, the lattice theory works in the manifestly holographic regime and successfully reproduces the most significant features of the warped theory. It is even in some respects better than the KK theory, which must be carefully regulated to obtain the correct physical results. Because it is easier to construct lattice theories than to find exact solutions to GR, we expect lattice gravity to be a useful tool for exploring field theory in curved space.
Date: July 11, 2005
Creator: Schwartz, Matthew; Randall, Lisa; Schwartz, Matthew D. & Thambyahpillai, Shiyamala
System: The UNT Digital Library
New cubic phase of lithium nitride to 200 GPa (open access)

New cubic phase of lithium nitride to 200 GPa

We present a new cubic ({gamma}) Li{sub 3}N phase discovered above 40({+-}5) GPa. Structure and electronic bands are examined at high pressure with synchrotron x-ray diffraction and inelastic x-ray scattering in a diamond anvil cell, and also with first-principles calculations. We observe a dramatic band-gap widening and volume collapse at the phase transition. {gamma}-Li{sub 3}N remains extremely stable and ionic to 200 GPa, with predicted metallization near 8 TPa. The high structural stability, wide band-gap and simple electronic structure of {gamma}-Li{sub 3}N are analogous to that of such lower valence closed-shell solids as NaCl, MgO and Ne, meriting its use as a low-Z internal pressure standard.
Date: July 19, 2005
Creator: Lazicki, A.; Maddox, B.; Evans, W.; Yoo, C. S.; McMahan, A. K.; Pickett, W. E. et al.
System: The UNT Digital Library
IMPROVED TECHNNOLOGY TO PREVENT ILLICIT TRAFFICKING IN NUCLEAR MATERIALS (open access)

IMPROVED TECHNNOLOGY TO PREVENT ILLICIT TRAFFICKING IN NUCLEAR MATERIALS

The proliferation of nuclear, chemical, and biological weapons (collectively known as weapons of mass destruction, or WMD) and the potential acquisition and use of WMD against the world by terrorists are extremely serious threats to international security. These threats are complex and interrelated. There are myriad routes to weapons of mass destruction--many different starting materials, material sources, and production processes. There are many possible proliferators--threshold countries, rogue states, state-sponsored or transnational terrorists groups, domestic terrorists, and even international crime organizations. Motives for acquiring and using WMD are similarly wide ranging--from a desire to change the regional power balance, deny access to a strategic area, or alter international policy to extortion, revenge, or hate. Because of the complexity of this threat landscape, no single program, technology, or capability--no silver bullet--can solve the WMD proliferation and terrorism problem. An integrated program is needed that addresses the WMD proliferation and terrorism problem from end to end, from prevention to detection, reversal, and response, while avoiding surprise at all stages, with different activities directed specifically at different types of WMD and proliferators. Radiation detection technologies are an important tool in the prevention of proliferation. A variety of new developments have enabled enhanced performance in …
Date: July 20, 2005
Creator: Richardson, J H
System: The UNT Digital Library
Effect of habitat and foraging height on bat activity in the coastal plain of South Carolina. (open access)

Effect of habitat and foraging height on bat activity in the coastal plain of South Carolina.

A comparison of bat activity levels in the Coastal Plain of South Carolina among 5 habitat types: forested riparian areas, clearcuts, young pine plantations, mature pine plantations and pine savannas, using time expansion radio-microphones and integrated detectors to simultaneously monitor bat activity at three heights in each habitat type.
Date: July 1, 2005
Creator: Menzel, Jennifer, M.; Menzel, Michael A.; Kilgo, John C.; Ford, W. Mark; Edwards, John W. & McCracken, Gary F.
System: The UNT Digital Library
Essential Grid Workflow Monitoring Elements (open access)

Essential Grid Workflow Monitoring Elements

Troubleshooting Grid workflows is difficult. A typicalworkflow involves a large number of components networks, middleware,hosts, etc. that can fail. Even when monitoring data from all thesecomponents is accessible, it is hard to tell whether failures andanomalies in these components are related toa given workflow. For theGrid to be truly usable, much of this uncertainty must be elim- inated.We propose two new Grid monitoring elements, Grid workflow identifiersand consistent component lifecycle events, that will make Gridtroubleshooting easier, and thus make Grids more usable, by simplifyingthe correlation of Grid monitoring data with a particular Gridworkflow.
Date: July 1, 2005
Creator: Gunter, Daniel K.; Jackson, Keith R.; Konerding, David E.; Lee,Jason R. & Tierney, Brian L.
System: The UNT Digital Library
Soft-x-ray spectroscopy study of nanoscale materials (open access)

Soft-x-ray spectroscopy study of nanoscale materials

The ability to control the particle size and morphology of nanoparticles is of crucial importance nowadays both from a fundamental and industrial point of view considering the tremendous amount of high-tech applications. Controlling the crystallographic structure and the arrangement of atoms along the surface of nanostructured material will determine most of its physical properties. In general, electronic structure ultimately determines the properties of matter. Soft X-ray spectroscopy has some basic features that are important to consider. X-ray is originating from an electronic transition between a localized core state and a valence state. As a core state is involved, elemental selectivity is obtained because the core levels of different elements are well separated in energy, meaning that the involvement of the inner level makes this probe localized to one specific atomic site around which the electronic structure is reflected as a partial density-of-states contribution. The participation of valence electrons gives the method chemical state sensitivity and further, the dipole nature of the transitions gives particular symmetry information. The new generation synchrotron radiation sources producing intensive tunable monochromatized soft X-ray beams have opened up new possibilities for soft X-ray spectroscopy. The introduction of selectively excited soft X-ray emission has opened a new …
Date: July 30, 2005
Creator: Guo, J.-H.
System: The UNT Digital Library
Bitmap Indices for Fast End-User Physics Analysis in ROOT (open access)

Bitmap Indices for Fast End-User Physics Analysis in ROOT

Most physics analysis jobs involve multiple selection steps on the input data. These selection steps are called ''cuts'' or ''queries''. A common strategy to implement these queries is to read all input data from files and then process the queries in memory. In many applications the number of variables used to define these queries is a relative small portion of the overall data set therefore reading all variables into memory takes unnecessarily long time. In this paper we describe an integration effort that can significantly reduce this unnecessary reading by using an efficient compressed bitmap index technology. The primary advantage of this index is that it can process arbitrary combinations of queries very efficiently, while most other indexing technologies suffer from the ''curse of dimensionality'' as the number of queries increases. By integrating this index technology with the ROOT analysis framework, the end-users can benefit from the added efficiency without having to modify their analysis programs. Our performance results show that for multi-dimensional queries, bitmap indices outperform the traditional analysis method up to a factor of 10.
Date: July 26, 2005
Creator: Stockinger, Kurt; Wu, Kesheng; Brun, Rene & Canal, Philippe
System: The UNT Digital Library
Using Visualization in Cockpit Decision Support Systems (open access)

Using Visualization in Cockpit Decision Support Systems

Beamline 7.2 of the Advanced Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL) is a beam diagnostics system that uses the synchrotron radiation emitted by a dipole magnet. It consists of two branches; in the first one the x-ray portion of the radiation is used in a pinhole camera system for measuring the transverse profile of the beam. The second branch is equipped with an x-ray beam position monitor (BPM) and with a multipurpose port where the visible and the far-infrared part of the radiation can be used for various applications such as bunch length measurements and IR coherent synchrotron radiation experiments. The pinhole system has been operating successfully since the end of 2003. The installation of the second branch has been completed recently and the results of its commissioning are presented in this paper together with examples of beam measurements performed at BL 7.2.
Date: July 1, 2005
Creator: Aragon, Cecilia R.
System: The UNT Digital Library
Using Visualization in Cockpit Decision Support Systems (open access)

Using Visualization in Cockpit Decision Support Systems

In order to safely operate their aircraft, pilots must makerapid decisions based on integrating and processing large amounts ofheterogeneous information. Visual displays are often the most efficientmethod of presenting safety-critical data to pilots in real time.However, care must be taken to ensure the pilot is provided with theappropriate amount of information to make effective decisions and notbecome cognitively overloaded. The results of two usability studies of aprototype airflow hazard visualization cockpit decision support systemare summarized. The studies demonstrate that such a system significantlyimproves the performance of helicopter pilots landing under turbulentconditions. Based on these results, design principles and implicationsfor cockpit decision support systems using visualization arepresented.
Date: July 1, 2005
Creator: Aragon, Cecilia R.
System: The UNT Digital Library
Toward Interoperable Mesh, Geometry and Field Components for PDE Simulation Development (open access)

Toward Interoperable Mesh, Geometry and Field Components for PDE Simulation Development

Mesh-based PDE simulation codes are becoming increasingly sophisticated and rely on advanced meshing and discretization tools. Unfortunately, it is still difficult to interchange or interoperate tools developed by different communities to experiment with various technologies or to develop new capabilities. To address these difficulties, we have developed component interfaces designed to support the information flow of mesh-based PDE simulations. We describe this information flow and discuss typical roles and services provided by the geometry, mesh, and field components of the simulation. Based on this delineation for the roles of each component, we give a high-level description of the abstract data model and set of interfaces developed by the Department of Energy's Interoperable Tools for Advanced Petascale Simulation (ITAPS) center. These common interfaces are critical to our interoperability goal, and we give examples of several services based upon these interfaces including mesh adaptation and mesh improvement.
Date: July 11, 2005
Creator: Chand, K K; Diachin, L F; Li, X; Ollivier-Gooch, C; Seol, E S; Shephard, M et al.
System: The UNT Digital Library
Melting of Xenon to 80 GPa, p-d hybridization, and an ISRO liquid (open access)

Melting of Xenon to 80 GPa, p-d hybridization, and an ISRO liquid

Measurements made in a laser heated diamond-anvil cell are reported that extend the melting curve of Xe to 80 GPa and 3350 K. The steep lowering of the melting slope (dT/dP) that occurs near 17 GPa and 2750 K results from the hybridization of the p-like valence and d-like conduction states with the formation of clusters in the liquid having Icosahedral Short-Range Order (ISRO).
Date: July 26, 2005
Creator: Ross, M; Boehler, R & Soderlind, P
System: The UNT Digital Library
Polymerization, shock cooling and ionization of liquid nitrogen (open access)

Polymerization, shock cooling and ionization of liquid nitrogen

The trajectory of thermodynamic states passed through by the nitrogen Hugoniot starting from the liquid and up to 10{sup 6} GPa has been studied. An earlier report of cooling in the doubly shocked liquid, near 50 to 100 GPa and 7500 K, is revisited in light of the recent discovery of solid polymeric nitrogen. It is found that cooling occurs when the doubly shocked liquid is driven into a volume near the molecular to polymer transition and raising the possibility of a liquid-liquid phase transition (LLPT). By increasing the shock pressure and temperature by an order of magnitude, theoretical calculations predict thermal ionization of the L shell drives the compression maxima to 5-6 fold compression at 10 Mbar (T {approx} 3.5 10{sup 5} K) and at 400 Mbar (T {approx} 2.3 10{sup 6} K) from K shell ionization. Near a pressure of 10{sup 6} GPa the K shell ionizes completely and the Hugoniot approaches the classical ideal gas compression fourfold limit.
Date: July 21, 2005
Creator: Ross, M & Rogers, F
System: The UNT Digital Library
ELM Suppression in Low Edge Collisionality H-Mode Discharges Using n=3 Magnetic Perturbations (open access)

ELM Suppression in Low Edge Collisionality H-Mode Discharges Using n=3 Magnetic Perturbations

Using resonant magnetic perturbations with toroidal mode number n = 3, we have produced H-mode discharges without edge localized modes (ELMs) which run with constant density and radiated power for periods up to about 2550 ms (17 energy confinement times). These ELM suppression results are achieved at pedestal collisionalities close to those desired for next step burning plasma experiments such as ITER and provide a means of eliminating the rapid erosion of divertor components in such machines which could be caused by giant ELMs. The ELM suppression is due to an enhancement in the edge particle transport which reduces the edge pressure gradient and pedestal current density below the threshold for peeling-ballooning modes. These n = 3 magnetic perturbations provide a means of active control of edge plasma transport.
Date: July 11, 2005
Creator: Burrell, K. H.; Evans, T. E.; Doyle, E. J.; Fenstermacher, M. E.; Groebner, R. J.; Leonard, A. W. et al.
System: The UNT Digital Library
Optimization of Carbon Coatings on LiFePO4 (open access)

Optimization of Carbon Coatings on LiFePO4

The electrochemical performance of LiFePO{sub 4} in lithium cells is strongly dependent on the structure (disordered/graphene or D/G ratio) of the in situ carbon produced during synthesis from carbon-containing precursors. Addition of pyromellitic acid (PA) prior to final calcination results in lower D/G ratios, yielding a higher-rate material. Further, improvements in electrochemical performance are realized when graphitization catalysts such as ferrocene are also added during LiFePO{sub 4} preparation, although overall carbon content is still less than 2 wt.%.
Date: July 14, 2005
Creator: Doeff, Marca M.; Wilcox, James D.; Kostecki, Robert & Lau, Grace
System: The UNT Digital Library
Di-boson production and SM SUSY Higgs searches at the Tevatron (open access)

Di-boson production and SM SUSY Higgs searches at the Tevatron

The discovery of the Higgs boson would be a major success for the Standard Model (SM) and would provide further insights into the electroweak symmetry breaking mechanism. This report contains the latest results from the D0 and CDF Tevatron experiments on searches for the SM Higgs produced from gluon fusion with H {yields} WW, and in association with a W boson. It also includes searches for a supersymmetric Higgs in the b{bar b} and {tau}{sup +}{tau}{sup -} decay channels. The study of di-boson production at the Tevatron is important to understand backgrounds in high mass Higgs searches. It also provides a test of the SM through the measurement of the production cross section and the gauge boson self couplings. This paper includes measurements of the WW, W{gamma}, and WZ production cross sections, as well as limits on the anomalous couplings associated with the WW{gamma} and WWZ interactions. The results are based on sets of up to 320 pb{sup -1} of data collected by the D0 and CDF experiments at the {bar p}p Tevatron collider, running at a center-of-mass energy of 1.96 TeV.
Date: July 1, 2005
Creator: Elvira, V. Daniel
System: The UNT Digital Library
Double Pomeron physics at the LHC (open access)

Double Pomeron physics at the LHC

The author discusses central exclusive production, also known as Double Pomeron Exchange DIPE, from the ISR through the Tevatron to the LHC. There the author emphasizes the interest of exclusive Higgs and W{sup +}W{sup -}/ZZ production.
Date: July 1, 2005
Creator: Albrow, Michael G.
System: The UNT Digital Library
Impact of a new Cerenkov light parameterisation on the reconstruction of shower profiles from Auger hybrid data (open access)

Impact of a new Cerenkov light parameterisation on the reconstruction of shower profiles from Auger hybrid data

The light signal measured by fluorescence telescopes receives--strongly depending on the shower geometry with respect to the detector--a non-negligible contribution from additionally produced Cherenkov light. This Cherenkov contribution has to be accounted for to determine primary parameters properly. In comparison to the previous ansatz used by other experiments, the impact of a new analytical description of Cherenkov light production in EAS on the Auger event reconstruction is investigated.
Date: July 1, 2005
Creator: Nerling, Frank; /Karlsruhe, Forschungszentrum; Bluemer, J.; /Karlsruhe, Forschungszentrum /Karlsruhe U.; Engel, R.; Unger, M. et al.
System: The UNT Digital Library
The performance of the corrector lenses for the Auger fluorescence detector (open access)

The performance of the corrector lenses for the Auger fluorescence detector

We present an analysis of the effect that the corrector lenses (Schmidt Optics) have on the overall performance of the Auger Fluorescence Detector. The analysis uses real data from the telescopes. Figures of merit for the corrector lenses performance include shower trigger rate and the distribution of the distance of closest approach to the shower axis. As a result of this analysis we may say that the effective light collection area of a telescope nearly doubles with the use of a corrector lens at its aperture.
Date: July 1, 2005
Creator: Sato, Ricardo; Escobar, Carlos O. & U., /Campinas State
System: The UNT Digital Library
The MiniBooNE primary beamline (open access)

The MiniBooNE primary beamline

None
Date: July 1, 2005
Creator: Kobilarcik, Thomas R.
System: The UNT Digital Library
NuTeV structure function measurement (open access)

NuTeV structure function measurement

The NuTeV experiment obtained high statistics samples of neutrino and antineutrino charged current events during the 1996-1997 Fermilab fixed target run. The experiment combines sign-selected neutrino and antineutrino beams and the upgraded CCFR iron-scintillator neutrino detector. A precision continuous calibration beam was used to determine the muon and hadron energy scales to a precision of 0.7% and 0.43% respectively. The structure functions F{sub 2}(x, Q{sup 2}) and xF{sub 3}(x, Q{sup 2}) obtained by fitting the y-dependence of the sum and the difference of the {nu} and {bar {nu}} differential cross sections are presented.
Date: July 1, 2005
Creator: Tzanov, M. & U., /Pittsburgh
System: The UNT Digital Library
Detection of very inclined showers with the Auger Observatory (open access)

Detection of very inclined showers with the Auger Observatory

The Pierre Auger Observatory can detect air showers with high efficiency at large zenith angles with both the fluorescence and surface detectors. Since half the available solid angle corresponds to zeniths between 60 and 90 degrees, a large number of inclined events can be expected and are indeed observed. In this paper, we characterize the inclined air showers detected by the Observatory and we present the aperture for inclined showers and an outlook of the results that can be obtained in future studies of the inclined data set.
Date: July 1, 2005
Creator: Nellen, Lukas & /Mexico U., ICN
System: The UNT Digital Library
Post-inflation increase of the cosmological tensor-to-scalar perturbation ratio (open access)

Post-inflation increase of the cosmological tensor-to-scalar perturbation ratio

We investigate the possibility that the amplitude of scalar density perturbations may be damped after inflation. This would imply that CMB anisotropies do not uniquely fix the amplitude of the perturbations generated during inflation and that the present tensor-to-scalar ratio might be larger than produced in inflation, increasing the prospects of detection of primordial gravitational radiation. It turns out, however, that the damping of density perturbations is hard to achieve.
Date: July 1, 2005
Creator: Bartolo, N.; /ICTP, Trieste; Kolb, Edward W.; /Fermilab /Chicago U., Astron. Astrophys. Ctr. /Chicago U., EFI; Riotto, A. & /Padua U. /INFN, Padua
System: The UNT Digital Library
Top quark mass and properties at the Tevatron (open access)

Top quark mass and properties at the Tevatron

We present recent analyses of top quark properties performed at Run II of the Tevatron. Measurements of the top quark mass, branching ratios and W boson helicity inside top quark decays are covered.
Date: July 1, 2005
Creator: Arguin, Jean-Francois & U., /Toronto
System: The UNT Digital Library