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Charged Particle Production In The Pb+Pb System At 158 [Formula Presented] Per Nucleon, P. Deines-Jones, M. L. Cherry, A. Dabrowska, R. Holynski, D. Kudzia, B. S. Nilsen, A. Olszewski, M. Szarska, A. Trzupek, C. J. Waddington, J. P. Wefel, B. Wilczynska, H. Wilczynski, W. Wolter, B. Wosiek, K. Wozniak Jan 2000

Charged Particle Production In The Pb+Pb System At 158 [Formula Presented] Per Nucleon, P. Deines-Jones, M. L. Cherry, A. Dabrowska, R. Holynski, D. Kudzia, B. S. Nilsen, A. Olszewski, M. Szarska, A. Trzupek, C. J. Waddington, J. P. Wefel, B. Wilczynska, H. Wilczynski, W. Wolter, B. Wosiek, K. Wozniak

Faculty Publications

Charged particle multiplicities from high-multiplicity interactions of 158 GeV/nucleon Pb ions with Pb target nuclei have been measured using high-resolution nuclear emulsion chambers with sensitivity from the peak of the pseudorapidity distribution forward to [Formula Presented] The characteristics of these interactions have been compared to those of central interactions of 200 GeV/nucleon proton, O, and S beams on silver or bromine targets and to results from simulations using the FRITIOF 7.02 and VENUS 4.12 Monte Carlo event generators. Multiplicities scale with the number of wounded nucleons, although the multiplicities for Pb+Pb interactions in the central region are significantly lower than …

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Evidence For Changing Of Cosmic Ray Composition Between 1017 And 1018 Ev From Multicomponent Measurements, T. Abu-Zayyad, K. Belov, D. J. Bird, J. Boyer, Z. Cao, M. Catanese, G. F. Chen, R. W. Clay, C. E. Covault, J. W. Cronin, H. Y. Dai, B. R. Dawson, J. W. Elbert, B. E. Fick, L. F. Fortson, J. W. Fowler, K. G. Gibbs, M. A.K. Glasmacher, K. D. Green, Y. Ho, A. Haung, C. C. Jui, M. J. Kidd, D. B. Kieda, B. C. Knapp, S. Ko, C. G. Larsen, W. Lee, E. C. Loh, E. J. Mannel, J. Matthews, J. N. Matthews, B. J. Newport Jan 2000

Evidence For Changing Of Cosmic Ray Composition Between 1017 And 1018 Ev From Multicomponent Measurements, T. Abu-Zayyad, K. Belov, D. J. Bird, J. Boyer, Z. Cao, M. Catanese, G. F. Chen, R. W. Clay, C. E. Covault, J. W. Cronin, H. Y. Dai, B. R. Dawson, J. W. Elbert, B. E. Fick, L. F. Fortson, J. W. Fowler, K. G. Gibbs, M. A.K. Glasmacher, K. D. Green, Y. Ho, A. Haung, C. C. Jui, M. J. Kidd, D. B. Kieda, B. C. Knapp, S. Ko, C. G. Larsen, W. Lee, E. C. Loh, E. J. Mannel, J. Matthews, J. N. Matthews, B. J. Newport

Faculty Publications

The average mass composition of cosmic rays with primary energies between 1017 and 1018eV has been studied using a hybrid detector consisting of the High Resolution Fly's Eye (HiRes) prototype and the MIA muon array. Measurements have been made of the change in the depth of shower maximum and the muon density as a function of energy. The results show that the composition is changing from a heavy to lighter mix as the energy increases. © 2000 The American Physical Society.

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Effect Of Interfacial Tension On Propagating Polymerization Fronts, R. Texier-Picard, J. A. Pojman, Vit A. Volpert Jan 2000

Effect Of Interfacial Tension On Propagating Polymerization Fronts, R. Texier-Picard, J. A. Pojman, Vit A. Volpert

Faculty Publications

This paper is devoted to the investigation of polymerization fronts converting a liquid monomer into a liquid polymer. We assume that the monomer and the polymer are immiscible and study the influence of the interfacial tension on the front stability. The mathematical model consists of the reaction-diffusion equations coupled with the Navier-Stokes equations through the convection terms. The jump conditions at the interface take into account the interfacial tension. Simple physical arguments show that the same temperature distribution could not lead to Marangoni instability for a nonreacting system. We fulfill a linear stability analysis and show that interaction of the …

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Ligand Dissociation Accelerated By Spin State Change: Locating The Minimum Energy Crossing Point For Phosphine Exchange In Cpmocl2(Pr3)2 Complexes, Kevin M. Smith, Rinaldo Poli, Jeremy N. Harvey Jan 2000

Ligand Dissociation Accelerated By Spin State Change: Locating The Minimum Energy Crossing Point For Phosphine Exchange In Cpmocl2(Pr3)2 Complexes, Kevin M. Smith, Rinaldo Poli, Jeremy N. Harvey

Faculty Publications

The minimum energy crossing point between the doublet and quartet potential energy surfaces of CpMoCl2(PH3)2 is calculated to lie 4.8 kcal mol-1 lower in energy than the doublet dissociative intermediate CpMoCl2(PH3). Implications for the influence of spin state changes on the rates of organometallic reactions are discussed.

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Measuring Geologic Time On Mars, Peter T. Doran, Steven L. Forman, Neil C. Sturchio, Stephen M. Clifford, Dimitri A. Papanastassiou Jan 2000

Measuring Geologic Time On Mars, Peter T. Doran, Steven L. Forman, Neil C. Sturchio, Stephen M. Clifford, Dimitri A. Papanastassiou

Faculty Publications

No abstract provided.

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Comparability Of Resting Energy Expenditure In Nigerians And U.S. Blacks, Amy Luke, Charles N. Rotimi, Adebowale A. Adeyemo, Ramon A. Durazo-Arvizu, T. Elaine Prewitt, Lisa Moragne-Kayser, Regina Marders, Richard S. Cooper Jan 2000

Comparability Of Resting Energy Expenditure In Nigerians And U.S. Blacks, Amy Luke, Charles N. Rotimi, Adebowale A. Adeyemo, Ramon A. Durazo-Arvizu, T. Elaine Prewitt, Lisa Moragne-Kayser, Regina Marders, Richard S. Cooper

Faculty Publications

Objective: To determine the influence of environmental factors on resting energy expenditure (REE) and its relationship to adiposity in two populations of West African origin, Nigerians and U.S. blacks. Research Methods and Procedures: REE and body composition were measured in a cross-sectional sample of 89 Nigerian adults (39 women and 50 men), and 181 U.S. black adults (117 women and 65 men). Both groups represent randomly selected population samples. REE was measured by indirect calorimetry after an overnight fast in both sites using the same instrument. Body composition was estimated using bioelectrical impedance analysis (BIA) in 72 Nigerians and 156 …

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Correlates Of Blood Pressure In An Urban Zimbabwean Population And Comparison To Other Populations Of African Origin, Jacob Mufunda, L. J. Scott, J. Chifamba, J. Matenga, B. Sparks, R. Cooper, H. Sparks Jan 2000

Correlates Of Blood Pressure In An Urban Zimbabwean Population And Comparison To Other Populations Of African Origin, Jacob Mufunda, L. J. Scott, J. Chifamba, J. Matenga, B. Sparks, R. Cooper, H. Sparks

Faculty Publications

We have evaluated the relationship between systolic blood pressure (SBP) and age, body mass index (BMI), waist circumference, sodium to potassium ratio (Na/K), and tobacco use in an urban African population. We conducted a random, population-based, cross-sectional survey of people 25 years and older in Marondera, Zimbabwe, with over-sampling in older age groups (n = 775), using a method comparable to that used in International Collaborative Study on Hypertension in Blacks (ICSHIB). The age-adjusted prevalences of hypertension in Marondera (SBP ≥140/DBP ≥90/antihypertensive medication) were 30% for women and 21% for men. The average BMI was 26.3 kg/m2 for women and …

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Influence Of The I/D Polymorphism Of The Angiotensin-Converting Enzyme Gene On The Outcome Of Microalbuminuria In Essential Hypertension, Josep Redon, Felipe Javier Chaves, Youlian Liao, Jose Maria Pascual, Eduardo Rovira, Maria Eugenia Armengod, Richard S. Cooper Jan 2000

Influence Of The I/D Polymorphism Of The Angiotensin-Converting Enzyme Gene On The Outcome Of Microalbuminuria In Essential Hypertension, Josep Redon, Felipe Javier Chaves, Youlian Liao, Jose Maria Pascual, Eduardo Rovira, Maria Eugenia Armengod, Richard S. Cooper

Faculty Publications

The objective of the present study was to analyze the influence of the I/D polymorphism of the ACE gene on the outcome of microalbuminuria in essential hypertensive patients who were receiving antihypertensive treatment. One hundred thirty-six essential hypertensive patients who were period, patients received nonpharmacological treatment consisting of moderate salt restriction and a low-calorie diet they were obese, with or without a regimen of antihypertensive drugs based on β-blockers or ACE inhibitors. Hydrochlorothiazide was added when necessary to maintain the blood pressure goal of <135/85 mm Hg. At the beginning of the study and at yearly intervals, systolic and diastolic blood pressures (SBP and DBP, respectively), 24-hour urinary albumin excretion (UAE), renal function, and biochemical profile measurements were made. The insertion/deletion (I/D) polymorphism of the ACE gene was determined through the use of polymerase chain reaction. The variables used in the statistical analysis were the measurements at the start of the study and the increase or decrease detected during the follow-up, estimated as individual specific regression line slope values. At baseline, no differences in blood pressure or UAE values were observed among genotypes. Likewise, the genotype or allele frequency was not significantly different between normoalbuminurics and microalbuminurics. After the 3 treatment years, significant reductions in SBP, DBP, and UAE were found (SBP 151.6 ± 17.3 reduced to 137.2 ± 14.3 mm Hg, P < 0.001; DBP 96.6 ± 8.9 reduced to 84.5 ± 9.8 mm Hg, P < 0.001; UAE 36.7 ± 71.5 reduced to 28.3 ± 78.6 mg/24 h, P < 0.05). The slopes of these parameters over time did not differ significantly among genotypes. The slope of SBP was the main factor related to the slope of logUAE (P < 0.003). A significant positive correlation coefficient between the SBP and logUAE slopes was observed for the DD patients (r = 0.57, P < 0.0001) but was absent in patients carrying the I allele (II r = -0.03, P = NS; I/D r = 0.01, P=NS). Follow-up studies should be used to achieve a better understanding of the impact of candidate gene polymorphisms on the development of hypertension-induced organ damage. Assessment of the I/D polymorphism of the ACE gene may identify subjects who require a greatly lowered blood pressure to prevent organ damage and to reduce hypertension- associated complications and death.

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Lack Of Association Between A Biallelic Polymorphism In The Adducin Gene And Blood Pressure In Whites And African Americans, Nicholas J. Schork, Aravinda Chakravarti, Bonnie Thiel, Myriam Fornage, Howard J. Jacob, Robin Cai, Charles N. Rotimi, Richard S. Cooper, Alan B. Weder Jan 2000

Lack Of Association Between A Biallelic Polymorphism In The Adducin Gene And Blood Pressure In Whites And African Americans, Nicholas J. Schork, Aravinda Chakravarti, Bonnie Thiel, Myriam Fornage, Howard J. Jacob, Robin Cai, Charles N. Rotimi, Richard S. Cooper, Alan B. Weder

Faculty Publications

Population-based candidate gene association analyses are becoming increasingly popular as a result of a greater number of genes and gene polymorphisms having been identified for which some functional information is available. Because many biochemical and physiologic systems impact blood pressure regulation and hypertension susceptibility, many of these identified genes and polymorphisms are candidates for population-level association studies involving blood pressure levels or hypertension status. Recent studies have suggested that the α-adducin gene may harbor polymorphisms that influence blood pressure level. Therefore, we embarked on a study to test one such polymorphism in two large US samples: one from an urban …

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Localization Of A Small Genomic Region Associated With Elevated Ace, Xiaofeng Zhu, Colin A. Mckenzie, Terrence Forrester, Deborah A. Nickerson, Ulrich Broeckel, Heribert Schunkert, Angela Doering, Howard J. Jacob, Richard S. Cooper, Mark J. Rieder Jan 2000

Localization Of A Small Genomic Region Associated With Elevated Ace, Xiaofeng Zhu, Colin A. Mckenzie, Terrence Forrester, Deborah A. Nickerson, Ulrich Broeckel, Heribert Schunkert, Angela Doering, Howard J. Jacob, Richard S. Cooper, Mark J. Rieder

Faculty Publications

Defining the relationship between multiple polymorphisms in a small genomic region and an underlying quantitative trait locus (QTL) represents a major challenge in human genetics. Pedigree analyses have shown that angiotensin I-converting enzyme (ACE) levels are influenced by a QTL located within or close to the ACE gene and most likely resides in the 3' region of this locus. We genotyped seven polymorphisms spanning 13 kb in the 3' end of ACE in 159 Afro-Caribbean subjects to evaluate the linkage disequilibrium between these sites and to narrow the genomic region associated with an elevated ACE level using a cladistic analysis. …

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Effect Of Silicon Rate And Host Resistance On Blast, Scald, And Yield Of Upland Price, K. W. Seebold, L. E. Datnoff, F. J. Correa-Victoria, T. A. Kucharek, G. H. Snyder Jan 2000

Effect Of Silicon Rate And Host Resistance On Blast, Scald, And Yield Of Upland Price, K. W. Seebold, L. E. Datnoff, F. J. Correa-Victoria, T. A. Kucharek, G. H. Snyder

Faculty Publications

Blast-resistant, partially resistant, and susceptible cultivars of rice were planted in soil amended with Si at 0, 500, or 1,000 kg/ha at two locations in eastern Colombia to assess differential responses to leaf blast, neck blast, and leaf scald, and to examine the quantity and quality of grains harvested. Leaf and neck blast on partially resistant and susceptible cultivars were reduced by Si as the rate of Si was increased. Depending on the location, the level of severity of leaf and neck blast on partially resistant cultivars, when fertilized with Si at 500 or 1,000 kg/ha, was lowered to that …

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Bill Clinton's Operational Code: Assessing Source Material Bias, Mark Schafer, Scott Crichlow Jan 2000

Bill Clinton's Operational Code: Assessing Source Material Bias, Mark Schafer, Scott Crichlow

Faculty Publications

This paper considers Bill Clinton's operational code as reflected in prepared speeches and spontaneous remarks. Differences between the two types of verbal material, their respective differences over time, and their respective variation after key intervening political events were subjected to analysis of variance as well as descriptive analyses. The results suggest that measurements based on spontaneous comments are preferable, particularly in providing sensitive measures of personal predispositions.

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Lie Semigroups With Triple Decompositions, Jimmie Lawson, Yongdo Lim Jan 2000

Lie Semigroups With Triple Decompositions, Jimmie Lawson, Yongdo Lim

Faculty Publications

In this paper we establish that the causal order determined by an Ol'shanski semigroup on the corresponding homogeneous space is globally hyperbolic. Using this fact, we present sufficient conditions for a special class of Lie semigroups to admit a canonical "triple decomposition," namely those for which the Lie algebra is of Cayley type. This theory applies in particular to semigroups which are naturally associated to euclidean Jordan algebras as the semigroup of compressions of the symmetric cone of the algebra.

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Lower Oceanic Crust Formed At An Ultra-Slow-Spreading Ridge: Ocean Drilling Program Hole 735b, Southwest Indian Ridge, Paul T. Robinson, Henry J.B. Dick, James H. Natland, J. C. Alt, W. Bach, D. Bideau, J. S. Gee, S. Haggis, J. Hertogen, G. Hirth, P. M. Holm, B. Ildefonse, G. J. Iturrino, B. E. John, D. S. Kelley, E. Kikawa, A. Kingdon, P. J. Leroux, J. Maeda, P. S. Meyer, D. J. Miller, H. R. Naslund, Y. L. Niu, J. Snow, R. A. Stephen, P. W. Trimby, H. U. Worm, A. Yoshinobu Jan 2000

Lower Oceanic Crust Formed At An Ultra-Slow-Spreading Ridge: Ocean Drilling Program Hole 735b, Southwest Indian Ridge, Paul T. Robinson, Henry J.B. Dick, James H. Natland, J. C. Alt, W. Bach, D. Bideau, J. S. Gee, S. Haggis, J. Hertogen, G. Hirth, P. M. Holm, B. Ildefonse, G. J. Iturrino, B. E. John, D. S. Kelley, E. Kikawa, A. Kingdon, P. J. Leroux, J. Maeda, P. S. Meyer, D. J. Miller, H. R. Naslund, Y. L. Niu, J. Snow, R. A. Stephen, P. W. Trimby, H. U. Worm, A. Yoshinobu

Faculty Publications

Ocean Drilling Program (ODP) Hole 735B, drilled on Legs 118 and 176, penetrated 1508 m of oceanic layer 3 on a transverse ridge adjacent to the Atlantis II Fracture Zone, Southwest Indian Ridge. The cored sequence consists predominantly of olivine gabbro and troctolite and lesser amounts of gabbro, microgabbro, and gabbronorite rich in Fe-Ti oxides. The section contains five major blocks of relatively primitive olivine gabbro and troctolite, composed of many smaller igneous bodies. Each of these composite blocks shows a small upward decrease in Mg# [defined as 100 × Mg/(Mg + Fe2+)] and contains more fractionated Fe- and Ti-rich …

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On The Structure Of 3-Connected Matroids And Graphs, James Oxley, Haidong Wu Jan 2000

On The Structure Of 3-Connected Matroids And Graphs, James Oxley, Haidong Wu

Faculty Publications

An element e of a 3-connected matroid M is essential if neither the deletion M\e nor the contraction M/e is 3-connected. Tutte's Wheels and Whirls Theorem proves that the only 3-connected matroids in which every element is essential are the wheels and whirls. In this paper, we consider those 3-connected matroids that have some non-essential elements, showing that every such matroid M must have at least two such elements. We prove that the essential elements of M can be partitioned into classes where two elements are in the same class if M has a fan, a maximal partial wheel, containing …

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Generalized Δ-Y Exchange And K-Regular Matroids, James Oxley, Charles Semple, Dirk Vertigan Jan 2000

Generalized Δ-Y Exchange And K-Regular Matroids, James Oxley, Charles Semple, Dirk Vertigan

Faculty Publications

This paper introduces a generalization of the matroid operation of Δ-Y exchange. This new operation, segment-cosegment exchange, replaces a coindependent set of k collinear points in a matroid by an independent set of k points that are collinear in the dual of the resulting matroid. The main theorem of the first half of the paper is that, for every field, or indeed partial field, F, the class of matroids representable over F is closed under segment-cosegment exchanges. It follows that, for all prime powers q, the set of excluded minors for GF(q)-representability has at least 2q-4 members. In the second …

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Exact Relations For Effective Tensors Of Composites: Necessary Conditions And Sufficient Conditions, Yury Grabovsky, Graeme W. Milton, Daniel S. Sage Jan 2000

Exact Relations For Effective Tensors Of Composites: Necessary Conditions And Sufficient Conditions, Yury Grabovsky, Graeme W. Milton, Daniel S. Sage

Faculty Publications

Typically the elastic and electrical properties of composite materials are strongly microstructure dependent. So it comes as a nice surprise to come across exact formulae for effective moduli that are universally valid no matter what the microstructure. Such exact formulae provide useful benchmarks for testing numerical and actual experimental data and for evaluating the merit of various approximation schemes. They can also be regarded as fundamental invariances existing in a given physical context. Classic examples include Hill's formulae for the effective bulk modulus of a two-phase mixture when the phases have equal shear moduli, Levin's formulae linking the effective thermal …

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Coulomb Gap: How A Metal Film Becomes An Insulator, V. Y.U. Butko, J. F. Ditusa, P. W. Adams Jan 2000

Coulomb Gap: How A Metal Film Becomes An Insulator, V. Y.U. Butko, J. F. Ditusa, P. W. Adams

Faculty Publications

Electron tunneling measurements of the density of states (DOS) in ultrathin Be films reveal that a correlation gap mediates their insulating behavior. In films with sheet resistance Rln(V) Efros-Shklovskii Coulomb gap spectrum finally emerges in the highest R films. Transport measurements of films which display this gap are well described by a universal variable range hopping law R(T) = (h/2e2)exp(T0/T)1/2. © 2000 The American Physical Society.

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Lower Bounds For Two-Level Additive Schwarz Preconditioners With Small Overlap, Susanne C. Brenner Jan 2000

Lower Bounds For Two-Level Additive Schwarz Preconditioners With Small Overlap, Susanne C. Brenner

Faculty Publications

Lower bounds for the condition numbers of the preconditioned systems are obtained for two-level additive Schwarz preconditioners. They show that the known upper bounds for both second order and fourth order problems are sharp in the case of a small overlap.

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Trimethyl(Trifluorovinyl)Silane, Roxana M. Trifu, George L. Gould Jan 2000

Trimethyl(Trifluorovinyl)Silane, Roxana M. Trifu, George L. Gould

Faculty Publications

No abstract provided.

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Gravitational Radiation From Schwarzschild Black Holes: The Second-Order Perturbation Formalism, Reinaldo J. Gleiser, Carlos O. Nicasio, Richard H. Price, Jorge Pullin Jan 2000

Gravitational Radiation From Schwarzschild Black Holes: The Second-Order Perturbation Formalism, Reinaldo J. Gleiser, Carlos O. Nicasio, Richard H. Price, Jorge Pullin

Faculty Publications

The perturbation theory of black holes has been useful recently for providing estimates of gravitational radiation from the black-hole collisions. Second-order perturbation theory, relatively undeveloped until recently, has proved to be important both for providing refined estimates and for indicating the range of validity of perturbation theory. Here we review the second-order formalism for perturbations of Schwarzschild spacetimes. The emphasis is on practical methods for carrying out the second-order computations of the outgoing radiation. General issues are illustrated throughout with examples from "close-limit" results, perturbation calculations in which black holes start from the small separation. © 2000 Elsevier Science B.V.

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Grazing Collisions Of Black Holes Via The Excision Of Singularities, Steve Brandt, Randall Correll, Roberto Gómez, Mijan Huq, Pablo Laguna, Luis Lehner, Pedro Marronetti, Richard A. Matzner, David Pullin, Jorge Pullin, Erik Schnetter, Deirdre Shoemaker, Jeffrey Winicour Jan 2000

Grazing Collisions Of Black Holes Via The Excision Of Singularities, Steve Brandt, Randall Correll, Roberto Gómez, Mijan Huq, Pablo Laguna, Luis Lehner, Pedro Marronetti, Richard A. Matzner, David Pullin, Jorge Pullin, Erik Schnetter, Deirdre Shoemaker, Jeffrey Winicour

Faculty Publications

We present the first simulations of non-headon (grazing) collisions of binary black holes in which the black hole singularities have been excised from the computational domain. Initially two equal mass black holes m are separated a distance ≈10m and with impact parameter ≈2m. Initial data are based on superposed, boosted (velocity ≈0.5c) solutions of single black holes in Kerr-Schild coordinates. Both rotating and non-rotating black holes are considered. The excised regions containing the singularities are specified by following the dynamics of apparent horizons. Evolutions of up to t≈35m are obtained in which two initially separate apparent horizons are present for …

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Consistent Canonical Quantization Of General Relativity In The Space Of Vassiliev Invariants, Cayetano Di Bartolo, Rodolfo Gambini, Jorge Griego, Jorge Pullin Jan 2000

Consistent Canonical Quantization Of General Relativity In The Space Of Vassiliev Invariants, Cayetano Di Bartolo, Rodolfo Gambini, Jorge Griego, Jorge Pullin

Faculty Publications

We present a quantization of the Hamiltonian and diffeomorphism constraint of canonical quantum gravity in the spin network representation. The novelty consists in considering a space of wavefunctions based on the Vassiliev knot invariants. The constraints are finite, well defined, and reproduce at the level of quantum commutators the Poisson algebra of constraints of the classical theory. A similar construction can be carried out in 2+1 dimensions leading to the correct quantum theory. © 2000 The American Physical Society.

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Second Order Perturbations Of A Schwarzschild Black Hole: Inclusion Of Odd Parity Perturbations, Carlos O. Nicasio, Reinaldo Gleiser, Jorge Pullin Jan 2000

Second Order Perturbations Of A Schwarzschild Black Hole: Inclusion Of Odd Parity Perturbations, Carlos O. Nicasio, Reinaldo Gleiser, Jorge Pullin

Faculty Publications

We consider perturbations of a Schwarzschild black hole that can be of both even and odd parity, keeping terms up to second order in perturbation theory, for the 1 = 2 axisymmetric case. We develop explicit formulae for the evolution equations and radiated energies and waveforms using the Regge-Wheeler-Zerilli approach. This formulation is useful, for instance, for the treatment in the "close limit approximation" of the collision of counterrotating black holes. © 2000 Plenum Publishing Corporation.

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Dynamics Of Diamagnetic Zeeman States Ionized By Half-Cycle Pulses, C. Rangan, K. J. Schafer, A. R.P. Rau Jan 2000

Dynamics Of Diamagnetic Zeeman States Ionized By Half-Cycle Pulses, C. Rangan, K. J. Schafer, A. R.P. Rau

Faculty Publications

We study the dynamical evolution of diamagnetic Zeeman states in hydrogen and sodium atoms ionized by half-cycle pulses. The eigenstates of the combined Coulomb-diamagnetic potential are determined by solving the Schrödinger equation using a grid-based pseudopotential method. We study states with principal quantum number n between [Formula Presented] in the [Formula Presented]-mixing regime at a magnetic field of 6 T. Diamagnetic states that are initially localized parallel and perpendicular to the magnetic field are subjected to the electric field of a half-cycle pulse (HCP) and their time evolution is monitored. We calculate the total ionized fraction, and also the spectrum …

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Photodetachment In Combined Static And Dynamic Electric Fields, Chitra Rangan, A. P. Rau Jan 2000

Photodetachment In Combined Static And Dynamic Electric Fields, Chitra Rangan, A. P. Rau

Faculty Publications

Through an exact solution of the time-dependent Schrödinger equation for an electron in a static electric field plus the time-dependent electric field of the detaching radiation, the photodetachment cross section of [Formula Presented] is calculated. Careful attention is paid to ensuring proper limiting behavior as the frequency of the time-dependent field goes to zero. We do not find observable effects of a cross term between the two fields on the detachment cross section. Our results point to possible gauge dependence and other difficulties of S-matrix formulations of multiphoton detachment and ionization. © 2000 The American Physical Society.

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Similarity Analysis Of Nonlinear Equations And Bases Of Finite Wavelength Solitons, A. Ludu, G. Stoitcheva, J. P. Draayer Jan 2000

Similarity Analysis Of Nonlinear Equations And Bases Of Finite Wavelength Solitons, A. Ludu, G. Stoitcheva, J. P. Draayer

Faculty Publications

We introduce a generalized similarity analysis which grants a qualitative description of the localised solutions of any nonlinear differential equation. This procedure provides relations between amplitude, width, and velocity of the solutions, and it is shown to be useful in analysing nonlinear structures like solitons, dublets, triplets, compact supported solitons and other patterns. We also introduce kink-antikink compact solutions for a nonlinear-nonlinear dispersion equation, and we construct a basis of finite wavelength functions having self-similar properties.

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Shell Model Description Of Normal Parity Bands In Odd-Mass Heavy Deformed Nuclei, C. Vargas, J. G. Hirsch, T. Beuschel, J. P. Draayer Jan 2000

Shell Model Description Of Normal Parity Bands In Odd-Mass Heavy Deformed Nuclei, C. Vargas, J. G. Hirsch, T. Beuschel, J. P. Draayer

Faculty Publications

The low-energy spectra and [Formula Presented] electromagnetic transition strengths of [Formula Presented] and [Formula Presented] are described using the pseudo SU(3) model. Normal parity bands are built as linear combinations of SU(3) states, which are the direct product of SU(3) proton and neutron states with pseudospin zero (for even number of nucleons) and pseudospin 1/2 (for odd number of nucleons). Each of the many-particle states has a well-defined particle number and total angular momentum. The Hamiltonian includes spherical Nilsson single-particle energies, the quadrupole-quadrupole and pairing interactions, as well as three rotor terms which are diagonal in the SU(3) basis. The …

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Movement And Territoriality Of Wintering Hermit Thrushes In Southeastern Louisiana, David R. Brown, Philip C. Stouffer, Cheryl M. Strong Jan 2000

Movement And Territoriality Of Wintering Hermit Thrushes In Southeastern Louisiana, David R. Brown, Philip C. Stouffer, Cheryl M. Strong

Faculty Publications

We describe the spatial organization and social behavior of Hermit Thrushes (Catharus guttatus) wintering in pine plantations and an adjacent hardwood forest in Tangipahoa Parish, Louisiana over three winters. We used point counts (n = 403) to collect data on agonistic behaviors and relative abundance within the study area. We used mist-netting to study site fidelity on four 9-ha plots within and among years. We used radio-telemetry to measure Hermit Thrushes' movements and territoriality (n = 50). We found that Hermit Thrushes saturated suitable patches within the study area. Most Hermit Thrushes actively defended small [mean = 0.55 ± 0.03 …

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Are Scientists In Developing Countries Isolated?, W. Shrum, P. Campion Jan 2000

Are Scientists In Developing Countries Isolated?, W. Shrum, P. Campion

Faculty Publications

Most scholars and development experts assume that scientists in developing countries are isolated, although some posit that they are part of a global scientific community. This paper seeks to determine the size of professional networks for scientists in less developed countries (LDC) as well as the distribution of their ties across organisational contexts and locations. Professional contact networks of scientists in Africa and Asia were determined in personal interviews with 293 researchers in universities, government laboratories and non-governmental organisations. Contrary to expectations, researchers in the least developed countries do not have the smallest networks. Results indicate that: (a) international and …

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