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University of Texas Rio Grande Valley

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Articles 2371 - 2400 of 2419

Full-Text Articles in Physical Sciences and Mathematics

Apex Version 2.0: Latest Version Of The Cross-Platform Analysis Program For Exafs, N. Dimakis, Grant Bunker Jan 2001

Apex Version 2.0: Latest Version Of The Cross-Platform Analysis Program For Exafs, N. Dimakis, Grant Bunker

Physics and Astronomy Faculty Publications and Presentations

This report describes recent progress on APEX, a free, open source, cross platform set of EXAFS data analysis software. In a previous report we described APEX 1.0 (Dimakis, N. and Bunker, G., 1999), a free and open source code suite of basic X-Ray Absorption Fine Structure (XAFS) data analysis programs for classical data reduction and single scattering analysis. The first version of APEX was the only cross platform (linux/irix/windows/MacOS) EXAFS analysis program to our knowledge, but it lacked important features like multiple scattering fitting, generic format conversion from ASCII to University of Washington (UW) binary-type files, and user friendly interactive …

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Modified Critical Correlations Close To Modulated And Rough Surfaces, Andreas Hanke, Mehran Kardar Jan 2001

Modified Critical Correlations Close To Modulated And Rough Surfaces, Andreas Hanke, Mehran Kardar

Physics and Astronomy Faculty Publications and Presentations

Correlation functions are sensitive to the presence of a boundary. Surface modulations give rise to modified near surface correlations, which can be measured by scattering probes. To determine these correlations, we develop a perturbative calculation in deformations in height from a flat surface. The results, combined with a renormalization group around four dimensions, are also used to predict critical behavior near a self-affine rough surface. We find that a large enough roughness exponent can modify surface critical behavior.

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Chemical Transferability Of Single- And Multiple-Scattering Exafs Debye-Waller Factors, N. Dimakis, Grant Bunker Jan 2001

Chemical Transferability Of Single- And Multiple-Scattering Exafs Debye-Waller Factors, N. Dimakis, Grant Bunker

Physics and Astronomy Faculty Publications and Presentations

Single- and multiple-scattering EXAFS Debye-Waller factors are amplitude reduction parameters that appear in the EXAFS x(k) equation accounting for the structural and thermal disorder of a given sample. These parameters must be known accurately in order to obtain quantitative agreement between theory and experiment. Since experimental data can only support a limited number of fitted parameters these factors must be known from another source. Although various approaches have been considered in the past with a variety of results, the self-consistent ab initio Density functional theory stands for the most accurate and reliable method regardless of molecular symmetry or other specific …

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Single-Pulse Characteristics Of The Millisecond Radio Pulsar Psr B1937 + 21 At 430 Mhz, F. A. Jenet, S. B. Anderson, T. A. Prince Jan 2001

Single-Pulse Characteristics Of The Millisecond Radio Pulsar Psr B1937 + 21 At 430 Mhz, F. A. Jenet, S. B. Anderson, T. A. Prince

Physics and Astronomy Faculty Publications and Presentations

The single-pulse characteristics of the millisecond pulsar PSR B1937 + 21 are studied using the recently installed Caltech baseband recorder at the Arecibo Radio Observatory in Puerto Rico. This is the first such analysis of this object that includes both average intensity pulses as well as \"giant pulses.\" Pulse ensemble-averaging techniques are developed in order to study the characteristics of PSR B1937 + 21's single pulses since the high time resolution signal-to-noise ratio is less than unity. This analysis reveals that the non-giant pulse radio emission is extremely stable. All observed fluctuations are consistent with diffractive interstellar scattering. Such intrinsic …

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Detection Of Variable Frequency Signals Using A Fast Chirp Transform, F. A. Jenet, T. A. Prince Dec 2000

Detection Of Variable Frequency Signals Using A Fast Chirp Transform, F. A. Jenet, T. A. Prince

Physics and Astronomy Faculty Publications and Presentations

The detection of signals with varying frequency is important in many areas of physics and astrophysics. The current work was motivated by a desire to detect gravitational waves from the binary inspirai of neutron stars and black holes, a topic of significant interest for the new generation of interferometric gravitational wave detectors such as LIGO. However, this work has significant generality beyond gravitational wave signal detection. We define a fast chirp transform (FCT) analogous to the fast Fourier transform. Use of the FCT provides a simple and powerful formalism for detection of signals with variable frequency just as Fourier transform …

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The Application And Performance Of A Generic Task Routine Decision Making Algorithm To Recipe Selection In Meal Planning, Michelle M. Cox Aug 2000

The Application And Performance Of A Generic Task Routine Decision Making Algorithm To Recipe Selection In Meal Planning, Michelle M. Cox

Theses and Dissertations - UTB/UTPA

A nutritional meal planning system was implemented to test the effectiveness of a previously developed routine decision making algorithm. The combinatorics involved in ordering recipes in all possible combinations to produce variability in a meal plan and provide sufficient nutrition is conceptually intensive. Meal planning involves selection of food to eat to fulfill a person's nutritional and personal preferences. This thesis demonstrates meal planning as a decision making problem and demonstrates the utility of the routine decision making algorithm by solving this problem. Generic Tasks, identified through artificial intelligence research, provides the basis for this algorithm. It uses user preferences …

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Interaction Of Mitochondrial Elongation Factor Tu With Aminoacyl-Trna And Elongation Factor Ts, Ying Chun Cai, James M. Bullard, Nancy L. Thompson, Linda L. Spremulli Jul 2000

Interaction Of Mitochondrial Elongation Factor Tu With Aminoacyl-Trna And Elongation Factor Ts, Ying Chun Cai, James M. Bullard, Nancy L. Thompson, Linda L. Spremulli

Chemistry Faculty Publications and Presentations

Elongation factor (EF) Tu promotes the binding of aminoacyl-tRNA (aa-tRNA) to the acceptor site of the ribosome. This process requires the formation of a ternary complex (EF-Tu·GTP·aa-tRNA). EF-Tu is released from the ribosome as an EF-Tu·GDP complex. Exchange of GDP for GTP is carried out through the formation of a complex with EF-Ts (EF-Tu·Ts). Mammalian mitochondrial EF-Tu (EF-Tumt) differs from the corresponding prokaryotic factors in having a much lower affinity for guanine nucleotides. To further understand the EF-Tumt subcycle, the dissociation constants for the release of aa-tRNA from the ternary complex (K tRNA) and for …

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Vas (Visual Analysis System): An Information Visualization Engine To Interpret World Wide Web Structure, Tarkan Karadayi May 2000

Vas (Visual Analysis System): An Information Visualization Engine To Interpret World Wide Web Structure, Tarkan Karadayi

Theses and Dissertations - UTB/UTPA

People increasingly encounter problems of interpreting and filtering mass quantities of information. The enormous growth of information systems on the World Wide Web has demonstrated that we need systems to filter, interpret, organize and present information in ways that allow users to use these large quantities of information. People need to be able to extract knowledge from this sometimes meaningful but sometimes useless mass of data in order to make informed decisions. Web users need to have some kind of information about the sort of page they might visit, such as, is it a rarely referenced or often-referenced page? This …

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P-Selectin Or Intercellular Adhesion Molecule (Icam)-1 Deficiency Substantially Protects Against Atherosclerosis In Apolipoprotein E-Deficient Mice, Robert G. Collins, Rizwan Velji, Natalia V. Guevara, M. John Hicks, Lawrence Chan, Arthur L. Beaudet Jan 2000

P-Selectin Or Intercellular Adhesion Molecule (Icam)-1 Deficiency Substantially Protects Against Atherosclerosis In Apolipoprotein E-Deficient Mice, Robert G. Collins, Rizwan Velji, Natalia V. Guevara, M. John Hicks, Lawrence Chan, Arthur L. Beaudet

Physics and Astronomy Faculty Publications and Presentations

The expression of leukocyte and endothelial cell adhesion molecules (CAMs) is essential for the emigration of leukocytes during an inflammatory response. The importance of the inflammatory response in the development of atherosclerosis is indicated by the increased expression of adhesion molecules, proinflammatory cytokines, and growth factors in lesions and lesion-prone areas and by protection in mice deficient in various aspects of the inflammatory response. We have quantitated the effect of deficiency for intercellular adhesion molecule (ICAM)-1, P-selectin, or E-selectin on atherosclerotic lesion formation at 20 wk of age in apolipoprotein (apo) E(- /-) (deficient) mice fed a normal chow diet. …

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Critical Adsorption On Defects In Ising Magnets And Binary Alloys, Andreas Hanke Jan 2000

Critical Adsorption On Defects In Ising Magnets And Binary Alloys, Andreas Hanke

Physics and Astronomy Faculty Publications and Presentations

Long-range correlations in a magnet close to its critical point or in a binary alloy close to a continuous order-disorder transition can substantially enhance the effect of local perturbations. It is demonstrated using a position-space renormalization procedure that quasi-one-dimensional defects which break the symmetry of the order parameter have pronounced effects: They cause long-range critical adsorption profiles and give rise to new universal critical exponents, which are identified and calculated using field-theoretical methods.

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Robust Test For Detecting Nonstationarity In Data From Gravitational Wave Detectors, Soumya Mohanty Jan 2000

Robust Test For Detecting Nonstationarity In Data From Gravitational Wave Detectors, Soumya Mohanty

Physics and Astronomy Faculty Publications and Presentations

It is difficult to choose detection thresholds for tests of nonstationarity that assume a priori a noise model if the data are statistically uncharacterized to begin with. This is a potentially serious problem when an automated analysis is required, as would be the case for the huge data sets that large interferometric gravitational wave detectors will produce. A solution is proposed in the form of a robust time-frequency test for detecting nonstationarity whose threshold for a specified false alarm rate is almost independent of the statistical nature of the ambient stationary noise. The efficiency of this test in detecting bursts …

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The Hî² Index As An Age Indicator Of Old Stellar Systems: The Effects Of Horizontal-Branch Stars, Hyun Chul Lee, Suk Jin Yoon, Young Wook Lee Jan 2000

The Hî² Index As An Age Indicator Of Old Stellar Systems: The Effects Of Horizontal-Branch Stars, Hyun Chul Lee, Suk Jin Yoon, Young Wook Lee

Physics and Astronomy Faculty Publications and Presentations

The strength of the Hβ index is computed for the integrated spectra of model globular clusters from the evolutionary population synthesis. For the first time, these models take into account the detailed systematic variation of horizontal-branch (HB) morphology with age and metallicity. Our models show that the Hβ index is significantly affected by the presence of blue HB stars. Because of the contribution from blue HB stars, the Hβ does not monotonically decrease as metallicity increases at a given age. Instead, it reaches a maximum strength when the distribution of HB stars is centered around 9500 K, the temperature at …

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Production Of The Subtropical Seagrass, Halodule Wrightii Aschers., In Lower Laguna Madre, Texas, Joseph L. Kowalski Dec 1999

Production Of The Subtropical Seagrass, Halodule Wrightii Aschers., In Lower Laguna Madre, Texas, Joseph L. Kowalski

Theses and Dissertations - UTB/UTPA

The autecology of shoal grass, Halodule wrightii Aschers., was studied at 1.2 m depth from June 1995 to February 1997 in Lower Laguna Madre (LLM), Texas. Halodule wrightii in LLM received about 47% surface irradiance, but otherwise displayed lower growth rates and biomass in nutrient-poor rhizosphere and water-column environments compared to H. wrightii populations in other Texas estuaries. High tissue N content and low C:N ratios belied low growth dynamics. Halodule wrightii in LLM is probably nutrient limited. A high nutrient demand by H. wrightii in a nutrient-poor environment may explain, in part, its gradual displacement by Thalassia testudinum and …

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Gravitational Radiation From Globular Clusters, M. Benacquista Jul 1999

Gravitational Radiation From Globular Clusters, M. Benacquista

Physics and Astronomy Faculty Publications and Presentations

Space-based gravitational wave detectors will have the ability to observe continuous low-frequency gravitational radiation from binary star systems. They can determine the direction to continuous sources with an angular resolution approaching tens of arcminutes. This resolution should be sufficient to identify binary sources as members of some nearby globular clusters. Thus, gravitational radiation can be used to determine the population of hard binaries in globular clusters. For particularly hard binaries, the orbital period may change as a result of gravitational wave emission. If one of these binaries can be identified with a globular cluster, then the distance to that cluster …

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The Weierstrass–Enneper System For Constant Mean Curvature Surfaces And The Completely Integrable Sigma Model, Paul Bracken, A. M. Grundland, L. Martina Jun 1999

The Weierstrass–Enneper System For Constant Mean Curvature Surfaces And The Completely Integrable Sigma Model, Paul Bracken, A. M. Grundland, L. Martina

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

The integrability of a system which describes constant mean curvature surfaces by means of the adapted Weierstrass–Enneper inducing formula is studied. This is carried out by using a specific transformation which reduces the initial system to the completely integrable two-dimensional Euclidean nonlinear sigma model. Through the use of the apparatus of differential forms and Cartan theory of systems in involution, it is demonstrated that the general analytic solutions of both systems possess the same degree of freedom. Furthermore, a new linear spectral problem equivalent to the initial Weierstrass–Enneper system is derived via the method of differential constraints. A new procedure …

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Role Of Reactive Oxygen Species In Mercapto-Methylimidazole-Induced Gastric Acid Secretion And Stress-Induced Gastric Ulceration, Uday Bandyopadhyay, Dipak Das, Debasish Bandyopadhyay, Mrinalini Bhattacharjee, Ranajit K. Banerjee Jan 1999

Role Of Reactive Oxygen Species In Mercapto-Methylimidazole-Induced Gastric Acid Secretion And Stress-Induced Gastric Ulceration, Uday Bandyopadhyay, Dipak Das, Debasish Bandyopadhyay, Mrinalini Bhattacharjee, Ranajit K. Banerjee

Chemistry Faculty Publications and Presentations

The objective of the present study is to delineate the role of reactive oxygen species in drug-induced gastric hyperacidity and stress-induced gastric ulceration. We reported earlier that mercaptomethylimidazole (MMI), an antithyroid drug, induces gastric acid (HCl) secretion partially through H2receptor activation of the parietal cell by histamine release and partially through an intracellular mechanism. While studying the latter, MMI-induced acid secretion was found to correlate well with the inactivation of the peroxidase, an important H2O2metabolizing enzyme of the mucosa. MMI activates the isolated parietal cell for acid secretion, which is sensitive to omeprazole. Peroxidase and catalase activity of the isolated …

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Critical Adsorption Near Edges, Andreas Hanke, M. Krech, F. Schlesener, S. Dietrich Jan 1999

Critical Adsorption Near Edges, Andreas Hanke, M. Krech, F. Schlesener, S. Dietrich

Physics and Astronomy Faculty Publications and Presentations

Symmetry breaking surface fields give rise to nontrivial and long-ranged order parameter profiles for critical systems such as fluids, alloys, or magnets confined to wedges. We discuss the properties of the corresponding universal scaling functions of the order parameter profile and the two-point correlation function, and determine the critical exponents η∥ and η⊥ for the so-called normal transition.

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Detecting An Association Between Gamma Ray And Gravitational Wave Bursts, Lee Samuel Finn, Soumya Mohanty, Joseph D. Romano Jan 1999

Detecting An Association Between Gamma Ray And Gravitational Wave Bursts, Lee Samuel Finn, Soumya Mohanty, Joseph D. Romano

Physics and Astronomy Faculty Publications and Presentations

If γ-ray bursts (GRBs) are accompanied by gravitational wave bursts (GWBs) the correlated output of two gravitational wave detectors evaluated in the moments just prior to a GRB will differ from that evaluated at other times. We can test for this difference without prior knowledge of either the GWB wave form or the detector noise spectrum. With a model for the GRB source population and GWB spectrum we can put a limit on the in-band rms GWB signal amplitude. Laser-Interferometer Gravitational Wave Observatory I detector observations coincident with 1000 GRB observations could lead us to exclude with 95% confidence associated …

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Rapid Single- And Multiple-Scattering Exafs Debye-Waller Factor Calculations On Active Sites Of Metalloproteins, N. Dimakis, M-Ali Al-Akhras, Grant Bunker Jan 1999

Rapid Single- And Multiple-Scattering Exafs Debye-Waller Factor Calculations On Active Sites Of Metalloproteins, N. Dimakis, M-Ali Al-Akhras, Grant Bunker

Physics and Astronomy Faculty Publications and Presentations

This paper describes recent results using our approach to calculating self-consistently single (SS) and multiple-scattering (MS) Debye- Waller factors (DWF) on active sites of metalloproteins. The calculation of MS DWF, together with the Feff7 program allows us to simulate ab-initio EXAFS spectra for a given temperature systems with no adjustable parameters. In our latest report (Dimakis N., and Bunker G., 1998) we calculate, using density functional and semiempirical approaches, the SS and MS DWF for small molecules and compared them to Raman, infrared and EXAFS spectra. In this report calculation of DWFs is done for tetrahedral Zn imidazole, a complex …

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Polymer Depletion Effects Near Mesoscopic Particles, Andreas Hanke, E. Eisenriegler, S. Dietrich Jan 1999

Polymer Depletion Effects Near Mesoscopic Particles, Andreas Hanke, E. Eisenriegler, S. Dietrich

Physics and Astronomy Faculty Publications and Presentations

The behavior of mesoscopic particles dissolved in a dilute solution of long, flexible, and nonadsorbing polymer chains is studied by field-theoretic methods. For spherical and cylindrical particles the solvation free energy for immersing a single particle in the solution is calculated explicitly. Important features are qualitatively different for self-avoiding polymer chains as compared with ideal chains. The results corroborate the validity of the Helfrich-type curvature expansion for general particle shapes and allow for quantitative experimental tests. For the effective interactions between a small sphere and a wall, between a thin rod and a wall, and between two small spheres, quantitative …

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Apex: Cross-Platform Analysis Program For Exafs, N. Dimakis, Grant Bunker Jan 1999

Apex: Cross-Platform Analysis Program For Exafs, N. Dimakis, Grant Bunker

Physics and Astronomy Faculty Publications and Presentations

We have developed version 1.0 of a freely available (including source code) suite of basic X-Ray Absorption Fine Structure (XAFS) data analysis programs for data reduction and single scattering analysis. This package is based on the University of Washington (UW/NRL) Fortran 77 programs that are available on the International XAFS Society (IXS) database, complemented by a graphical TCL/TK scripting language based user interface which runs virtually unchanged between platforms, using the native look and feel of the corresponding platform. The package has been tested on MacOS 8.1, Linux, IRIX, Windows95 and NT. Particular emphasis is placed on simplicity, reliability, and …

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Critical Adsorption On Curved Objects, Andreas Hanke, S. Dietrich Jan 1999

Critical Adsorption On Curved Objects, Andreas Hanke, S. Dietrich

Physics and Astronomy Faculty Publications and Presentations

A systematic field-theoretical description of critical adsorption on curved objects such as spherical or rodlike colloidal particles immersed in a fluid near criticality is presented. The temperature dependence of the corresponding order parameter profiles and of the excess adsorption are calculated explicitly. Critical adsorption on elongated rods is substantially more pronounced than on spherical particles. It turns out that, within the context of critical phenomena in confined geometries, critical adsorption on a microscopically thin ‘‘needle’’ represents a distinct universality class of its own. Under favorable conditions the results are relevant for the flocculation of colloidal particles.

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Observational Limit On Gravitational Waves From Binary Neutron Stars In The Galaxy, B. Allen, J. K. Blackburn, J. D. Creighton, Teviet Creighton Jan 1999

Observational Limit On Gravitational Waves From Binary Neutron Stars In The Galaxy, B. Allen, J. K. Blackburn, J. D. Creighton, Teviet Creighton

Physics and Astronomy Faculty Publications and Presentations

Using optimal matched filtering, we search 25 hours of data from the LIGO 40-m prototype laser interferometric gravitational-wave detector for gravitational-wave chirps emitted by coalescing binary systems within our Galaxy. This is the first test of this filtering technique on real interferometric data. An upper limit on the rate R of neutron star binary inspirals in our Galaxy is obtained: with 90% confidence, R<0.5h−1. Similar experiments with LIGO interferometers will provide constraints on the population of tight binary neutron star systems in the Universe.

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On Different Integrable Systems Sharing The Same Nondynamical R-Matrix, Zhijun Qiao, Walter Strampp May 1998

On Different Integrable Systems Sharing The Same Nondynamical R-Matrix, Zhijun Qiao, Walter Strampp

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

In a recent paper @Zhijun Qiao and Ruguang Zhou, Phys. Lett. A 235, 35 ~1997!#, the amazing fact was reported that a discrete and a continuous integrable system share the same r-matrix with the interesting property of being nondynamical. Now, we present three further pairs of different continuous integrable systems sharing the same r-matrix again being nondynamical. The first pair is the finite-dimensional constrained system ~FDCS! of the famous AKNS hierarchy and the Dirac hierarchy; the second pair is the FDCS of the well-known geodesic flows on the ellipsoid and the Heisenberg spin chain hierarchy; and the third pair is …

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Radio Pulse Properties Of The Millisecond Pulsar Psr J0437-4715. I. Observations At 20 Centimeters, F. A. Jenet, S. B. Anderson, V. M. Kaspi, T. A. Prince, S. C. Unwin May 1998

Radio Pulse Properties Of The Millisecond Pulsar Psr J0437-4715. I. Observations At 20 Centimeters, F. A. Jenet, S. B. Anderson, V. M. Kaspi, T. A. Prince, S. C. Unwin

Physics and Astronomy Faculty Publications and Presentations

We present a total of 48 minutes of observations of the nearby, bright millisecond pulsar PSR J0437-4715 taken at the Parkes Observatory in Australia. The data were obtained at a central radio frequency of 1380 MHz using a high-speed tape recorder that permitted coherent Nyquist sampling of 50 MHz of bandwidth in each of two polarizations. Using the high time resolution available from this voltage recording technique, we have studied a variety of single-pulse properties, many for the first time in a millisecond pulsar. We show that individual pulses are broad band, have pulse widths ranging from ∼ 10 (∼ …

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Hierarchical Search Strategy For The Detection Of Gravitational Waves From Coalescing Binaries: Extension To Post-Newtonian Waveforms, Soumya Mohanty Jan 1998

Hierarchical Search Strategy For The Detection Of Gravitational Waves From Coalescing Binaries: Extension To Post-Newtonian Waveforms, Soumya Mohanty

Physics and Astronomy Faculty Publications and Presentations

The detection of gravitational waves from coalescing compact binaries would be a computationally intensive process if a single bank of template wave forms (one step search) is used. In an earlier paper we presented a detection strategy, called a two step search, that utilizes a hierarchy of template banks. It was shown that in the simple case of a family of Newtonian signals, an on-line two step search was ≃8 times faster than an on-line one step search (for the initial LIGO). In this paper we extend the two step search to the more realistic case of …

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Searching For Periodic Sources With Ligo, Patrick R. Brady, Teviet Creighton, Curt Cutler, Bernard F. Schutz Jan 1998

Searching For Periodic Sources With Ligo, Patrick R. Brady, Teviet Creighton, Curt Cutler, Bernard F. Schutz

Physics and Astronomy Faculty Publications and Presentations

We investigate the computational requirements for all-sky, all-frequency searches for gravitational waves from spinning neutron stars, using archived data from interferometric gravitational wave detectors such as LIGO. These sources are expected to be weak, so the optimal strategy involves coherent accumulaton of signal-to-noise using Fourier transforms of long stretches of data (months to years). Earth-motion-induced Doppler shifts, and intrinsic pulsar spindown, will reduce the narrow-band signal-to-noise by spreading power across many frequency bins; therefore, it is necessary to correct for these effects before performing the Fourier transform. The corrections can be implemented by a parametrized model, in which one does …

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Critical Casimir Forces Between Spherical Particles In Fluids, Andreas Hanke, F. Schlesener, E. Eisenriegler, S. Dietrich Jan 1998

Critical Casimir Forces Between Spherical Particles In Fluids, Andreas Hanke, F. Schlesener, E. Eisenriegler, S. Dietrich

Physics and Astronomy Faculty Publications and Presentations

Long-ranged correlations in a fluid close to its critical point Tc cause distinct forces between immersed colloidal particles and the container walls. We calculate such a force and its temperature dependence for the generic case of a spherical particle located at a distance D from a planar wall and find that the force attains a maximum at a temperature Tmax(D) above Tc, which facilitates quantitative experimental tests. The corresponding effective pair interaction between the colloidal particles themselves, potentially leading to aggregation, is also discussed.

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A Data Analysis Approach For Detecting Gravitational Waves From Psr 0437-4715, Soumya Mohanty, I. S. Heng, David Blair, S. Dhurandhar, M. Tovar, E. Ivanov Jan 1998

A Data Analysis Approach For Detecting Gravitational Waves From Psr 0437-4715, Soumya Mohanty, I. S. Heng, David Blair, S. Dhurandhar, M. Tovar, E. Ivanov

Physics and Astronomy Faculty Publications and Presentations

A search for gravitational waves from the millisecond pulsar PSR 0437-4715 has been initiated using the bar detector NIOBE which is located at the University of Western Australia. We present a detailed report on the data analysis algorithm, called phase plane rotation, which will be used in this search. A discussion of the actual implementation of the algorithm is presented. The data analysis algorithm mentioned above has the advantage that it requires minimal changes to the already-existing data acquisition facility of NIOBE but, at the same time, it is as efficient as optimal filtering in detecting a signal. This …

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Ab Initio Single- And Multiple-Scattering Exafs Debye-Waller Factors: Raman And Infrared Data, N. Dimakis, Grant Bunker Jan 1998

Ab Initio Single- And Multiple-Scattering Exafs Debye-Waller Factors: Raman And Infrared Data, N. Dimakis, Grant Bunker

Physics and Astronomy Faculty Publications and Presentations

The extended x-ray-absorption fine structure (EXAFS) Debye-Waller factor is an essential term appearing in the EXAFS equation that accounts for the molecular structural and thermal disorder of a sample. Single- and multiple-scattering Debye-Waller factors must be known accurately to obtain quantitative agreement between theory and experiment. Since the total number of fitting parameters that can be varied is limited in general, data cannot support fitting of all relevant multiple-scattering Debye-Waller factors. Calculation of the Debye-Waller factors is typically done using the correlated Debye approximation, where a single parameter (Debye temperature) is varied. However, this procedure cannot account in general for …

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