Physical Sciences and Mathematics Commons^™

Inhomogeneity In Gelation And Nonuniversality Of Sol-To-Gel Transitions Studied By A Computer Simulation Model, Yi-Min Liu, R.B. Pandey

Faculty Publications

No abstract provided.

Investigating The Evolution Of Multifragmenting Systems With Fragment Emission Order, E. W. Cornell, T. M. Hamilton, D. Fox, Y. Lou, R. T. De Souza, M. J. Huang, W. C. Hsi, C. Schwarz, C. Williams, D. R. Bowman, J. Dinius, C. K. Gelbke, D. O. Handzy, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, L. Phair, M. B. Tsang, G. Vanburen, R. J. Charity, L. G. Sobotka, W. A. Friedman

Faculty Publications

Multifragment decays of central collisions in 84Kr+197Au at E/A=70MeV are studied. By utilizing a technique sensitive to the emission order of fragments, it is deduced that carbon fragments are emitted prior to beryllium fragments when these fragments have the same velocity. This observation is consistent with the cooling of a thermally decaying source.

Searching For The Nuclear Liquid-Gas Phase Transition In Au + Au Collisions At 35 Mev/Nucleon, M. Belkacem, P. F. Mastinu, V. Latora, A. Bonasera, M. D'Agostino, M. Bruno, J. D. Dinius, M. L. Fiandri, F. Gramegna, D. O. Handzy, W. C. Hsi, M. Huang, G. V. Margagliotti, P. M. Milazzo, C. P. Montoya, Graham F. Peaslee, R. Rui, C. Schwarz, G. Vannini, C. Williams

Faculty Publications

Within the framework of classical molecular dynamics, we study the collision Au+Au at an incident energy of 35 MeV/nucleon. It is found that the system shows a critical behavior at peripheral impact parameters, revealed through the analysis of conditional moments of charge distributions, Campi scatter plot, and the occurrence of large fluctuations in the region of the Campi plot where this critical behavior is expected. When applying the experimental filters of the MULTICS-MINIBALL apparatus, it is found that criticality signals can be hidden due to the inefficiency of the experimental apparatus. The signals are recovered by identifying semiperipheral and peripheral …

Mass Dependence Of Directed Collective Flow, M. J. Huang, R. C. Lemmon, F. Daffin, W. G. Lynch, C. Schwarz, M. B. Tsang, C. Williams, P. Danielewicz, K. Haglin, W. Bauer, N. Carlin, R. J. Charity, R. T. De Souza, C. K. Gelbke, W. C. Hsi, G. J. Kunde, M. C. Lemaire, M. A. Lisa, U. Lynen, Graham F. Peaslee, J. Pochodzalla, H. Sann, L. G. Sobotka, S. R. Souza, W. Trautmann

Faculty Publications

Sidewards directed fragment flow has been extracted for 84Kr+197Au collisions at E/A=200MeV, using techniques that are free of reaction plane dispersion. The fragment flow per nucleon increases with mass, following a thermal or coalescencelike behavior, and attains roughly constant limiting values at 4≤A≤12. Comparisons of the impact parameter dependences of the measured coalescence-invariant proton flow to Boltzmann-Uehling-Uhlenbeck calculations clearly favor a momentum dependent nuclear mean field.

Procedurally Rational Decision-Making And Control, Richard L. Frost, Michael A. Goodrich, Wynn C. Stirling

Faculty Publications

Substantive rationality requires a decision-maker to be a utility maximizer; under this paradigm, the decision is paramount, and not dependent on the computational process used to obtain it. Procedural rationality is dependent on the method used to make the decision; reasonableness of the procedure is paramount. Well-formed problems are amenable to substantive rationality; ill-formed problems are not, but are amenable to procedural rationality. To qualify as being procedurally rational, a methodology must possess a sound epistemological basis, it must be amenable to a formal design synthesis procedure, and it must be consistent with substantive rationality. Epistemic utility theory forms the …

A Fertility Channel Model For Post-Correction Of Continuous Speech Recognition, Eric K. Ringger, James F. Allen

Faculty Publications

We have implemented a post-processor called SPEECHPP to correct word-level errors committed by an arbitrary speech recognizer. Applying a noisy-channel model, SPEECHPP uses a Viterbi beam-search that employs language and channel models. Previous work demonstrated that a simple word-for-word channel model was sufficient to yield substantial incieases in word accuracy. This paper demonstrates that some improvements in word accuracy result from augmenting the channel model with an account of word fertility in the channel. This work further demonstrates that a modern continuous speech recognizer can be used in "black-box" fashion for robustly recognizing speech for which the recognizer was not …

Universality Of Spectator Fragmentation At Relativistic Bombarding Energies, A. Schüttauf, W. D. Kunze, A. Wörner, M. Begemann-Blaich, Th. Blaich, D. R. Bowman, R. J. Charity, A. Cosmo, A. Ferrero, C. K. Gelbke, C. Groß, W. C. Hsi, J. Hubele, G. Immé, I. Iori, J. Kempter, P. Kreutz, G. J. Kunde, V. Lindenstruth, M. A. Lisa, W. G. Lynch, U. Lynen, M. Mang, T. Möhlenkamp, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilvie, Graham F. Peaslee, J. Pochodzalla, G. Raciti, F. Rosenberger, Th. Rubehn, H. Sann, C. Schwarz, W. Seidei, V. Serfling

Faculty Publications

Multi-fragment decays of 129Xe, 197Au and 238U projectiles in collisions with Be, C, Al, Cu, In, Au and U targets at energies between View the MathML source and 1000 MeV have been studied with the ALADIN forward-spectrometer at SIS. By adding an array of 84 SiCsI(Tl) telescopes the solid-angle coverage of the setup was extended to θlab = 16°. This permitted the complete detection of fragments from the projectile-spectator source. The dominant feature of the systematic set of data is the Zbound universality that is obeyed by the fragment multiplicities and correlations. These observables are invariant with respect to the …

Charge Correlations And Dynamical Instabilities In The Multifragment Emission Process, L. G. Moretto, Th. Rubehn, L. Phair, N. Colonna, G. J. Wozniak, D. R. Bowman, Graham F. Peaslee, N. Carlin, R. T. De Souza, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, W. G. Lynch, C. Williams

Faculty Publications

A new, sensitive method allows one to search for the enhancement of events with nearly equal-sized fragments as predicted by theoretical calculations based on volume or surface instabilities. Simulations have been performed to investigate the sensitivity of the procedure. Experimentally, charge correlations of intermediate mass fragments emitted from heavy ion reactions at intermediate energies have been studied. No evidence for a preferred breakup into equal-sized fragments has been found.

Dijet Angular Distributions In Direct And Resolved Photoproduction At Hera, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. R. Okrasinski, J. Repond, R. Stanek, R. L. Talaga, H. Zhang, Margarita C. K. Mattingly, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, R. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, I. Gialas, R. Giusti, G. Iacobucci, G. Laurenti, G. Levi, A. Margotti, T. Massam

Faculty Publications

Jet photoproduction, where the two highest transverse energy (ETjet) jets have ETjet above 6 GeV and a jet-jet invariant mass above 23 GeV, has been studied with the ZEUS detector at the HERA ep collider. Resolved and direct photoproduction samples have been separated. The cross section as a function of the angle between the jet-jet axis and the beam direction in the dijet rest frame has been measured for the two samples. The measured angular distributions differ markedly from each other. They agree with the predictions of QCD calculations, where the different angular distributions reflect the different spins of the …

Observation Of Events With An Energetic Forward Neutron In Deep Inelastic Scattering At Hera, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. R. Okrasinski, J. Repond, R. Stanek, R. L. Talaga, H. Zhang, Margarita C. K. Mattingly, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, R. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, I. Gialas, R. Giusti, G. Iacobucci, G. Laurenti, G. Levi, A. Margotti, T. Massam

Faculty Publications

In deep inelastic neutral current scattering of positrons and protons at the center of mass energy of 300 GeV, we observe, with the ZEUS detector, events with a high energy neutron produced at very small scattering angles with respect to the proton direction. The events constitute a fixed fraction of the deep inelastic, neutral current event sample independent of Bjorken x and Q2 in the range 3 · 10-4 < xBJ < 6 · 10-3 and 10 < Q2 < 100 GeV2.

Study Of Charged-Current Ep Interactions At Q2 ≫ 200 Gev2 With The Zeus Detector At Hera, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. R. Okrasinski, J. Repond, R. Stanek, R. L. Talaga, H. Zhang, Margarita C. K. Mattingly, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, P. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti, G. Levi, A. Margotti

Faculty Publications

The cross sections for the deep inelastic charged-current interactions e+p → ν̄X and e-p → νX have been measured in the kinematic region x > 0.006 and Q2 > 200GeV2, using the e+p and e-p data collected with the ZEUS detector during 1993 and 1994. For the integrated cross sections, σe+→ν̄X(Q2>200 GeV2) = 30.3- 4.2+ 5.5 [stat] -2.6+1.6 [syst] pb σe-p→νX(Q2>200 GeV2) = 54.7-9.8+15.9 [stat] -3.4+2.8 [syst] pb are obtained, in good agreement with the Standard Model expectations of 32.3pb and 65.8pb. The differential cross sections have been measured as functions of Q2, x and y. The differences between e+p …

Kinetics And Jamming Coverage In A Random Sequential Adsorption Of Polymer Chains, Jian-Sheng Wang, Ras B. Pandey

Faculty Publications

No abstract provided.

Structural Phase Transition And Tc Distribution In Hf-Doped Lamno3 Investigated Using Perturbed-Angular-Correlation Spectroscopy, William E. Evenson, David D. Allred, Gary L. Catchen

Faculty Publications

Using perturbed-angular-correlation (PAC) spectroscopy, via the Hf-->Ta probe, we have measured Mn-site electric-field gradients (EFG's) at Ta nuclei in ceramic samples of LaMnO3. Two crystallographic phases coexist over a temperature interval of ≈16 K near the orthorhombic-to-rhombohedral transition at ≈724 K, which shows a thermal hysteresis of ≈1.7±0.2 K. Concurrently, in the two phases, we determined the temperature dependence of the EFG parameters, Vzz, ƞ, and δ, and the ratio of the probe concentrations A1/A2. To explain the apparent coexistence of two phases in this weakly first-order transition, we present a model that assumes a spatial distribution of Tc …

Reducibility, Thermal And Mass Scaling In Angular Correlations From Multifragmentation Reactions, L. Phair, L. G. Moretto, G. J. Wozniak, R. T. De Souza, D. R. Bowman, N. Carlin, C. K. Gelbke, W. G. Gong, Y. D. Kim, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, M. B. Tsang, F. Zhu

Faculty Publications

The azimuthal angular correlations of light charged particles and light intermediate mass fragments emitted from the reaction 36Ar+197Au at E/A=50MeV are found to be reducible to the angular distributions of individual fragments. Thermal scaling is also observed in the coefficients of the angular correlations. Furthermore, the observed scaling with fragment mass seems to imply secondary emission from relatively small ( A≈15–30) primary fragments.

Measurement Of The Reaction Γ*P→Φp In Deep Inelastic E+P Scattering At Hera, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. R. Okrasinski, J. Repond, R. Stanek, R. L. Talaga, H. Zhang, Margarita C. K. Mattingly, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, R. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, I. Gialas, R. Giusti, G. Iacobucci, G. Laurenti, G. Levi, A. Margotti, T. Massam

Faculty Publications

The production of φ mesons in the reaction e+p → e+φp (φ → K+K-), for 7 < Q2 < 25 GeV2 and for virtual photon-proton centre of mass energies (W) in the range 42-134 GeV, has been studied with the ZEUS detector at HERA. When compared to lower energy data at similar Q2, the results show that the γp → p0p cross section rises strongly with W. This behaviour is similar to that previously found for the γ*p → p0p cross section. This strong dependence cannot be explained by production through soft pomeron exchange. It is, however, consistent with perturbative QCD expectations, where it reflects the rise of the gluon momentum density in the proton at small x. The ratio of σ(φ)/σ(p0), which has previously been determined by ZEUS to be 0.065 ± 0.013 (stat.) in photoproduction at a mean W of 70 GeV, is measured to be 0.18 ± 0.05 (stat.) ± 0.03 (syst.) at a mean Q2 of 12.3 GeV2 and mean W of ≈ 100 GeV and is thus approaching at large Q2 the value of 2/9 predicted from the quark charges of the vector mesons and a flavour independent production mechanism.

Effects Of Climate Change On Hypoxia In Coastal Waters: A Doubled Co2 Scenario For The Northern Gulf Of Mexico, Dubravko Justic, Nancy N. Rabalais, R. Eugene Turner

Faculty Publications

Projections of general circulation models suggest that freshwater discharge from the Mississippi River to the coastal ocean will increase 20% if atmospheric CO2 concentration doubles. This result is likely to affect water column stability, surface productivity, and global oxygen cycling in the northern Gulf of Mexico, which is the site of the largest (up to 16,500 km2) and most severe hypoxic zone (liter‒1) in the western Atlantic Ocean. We use a coupled physical-biological two-box model to investigate potential effects of climate change on seasonal oxygen cycling and hypoxia in river-dominated coastal waters. The model was developed and calibrated using comprehensive …

Dynamics Of Conversion Of Conduction Electrons Into A Collective Charge-Density-Wave Current, Alexander S. Kovalev, Yuriy V. Pershin Dr, Alexander S. Rozhavsky

Faculty Publications

The exactly solvable model which describes the dynamics of transformation of conduction electrons into nonlinear charge-carrying excitations of charge-density waves in quasi-one-dimensional Peierls-Frohlich conductors is formulated and studied by the inverse scattering transformation method. The pair of self-trapped conduction electrons transform into a charged 2π kink localized in a single conducting chain and surrounded by dipoles in neighboring chains.

Robust Optimization Using Training Set Evolution, Tony R. Martinez, Dan A. Ventura

Faculty Publications

Training Set Evolution is an eclectic optimization technique that combines evolutionary computation (EC) with neural networks (NN). The synthesis of EC with NN provides both initial unsupervised random exploration of the solution space as well as supervised generalization on those initial solutions. An assimilation of a large amount of data obtained over many simulations provides encouraging empirical evidence for the robustness of Evolutionary Training Sets as an optimization technique for feedback and control problems.

Nutrient Changes In The Mississippi River And System Responses On The Adjacent Continental Shelf, Nancy N. Rabalais, R. Eugene Turner, Dubravko Justic, Quay Dortch, William J. Wiseman, Barun Sen Gupta

Faculty Publications

The Mississippi River system ranks among the world's top 10 rivers in freshwater and sediment inputs to the coastal ocean. The river contributes 90% of the freshwater loading to the Gulf of Mexico, and terminates amidst one of the United States' most productive fisheries regions and the location of the largest zone of hypoxia, in the western Atlantic Ocean. Significant increases in riverine nutrient concentrations and loadings of nitrate and phosphorus and decreases in silicate have occurred this century, and have accelerated since 1950. Consequently, major alterations have occurred in the probable nutrient limitation and overall stoichiometric nutrient balance in …

A Robust System For Natural Spoken Dialogue, Eric K. Ringger, James F. Allen, Bradford W. Miller, Teresa Sikorski

Faculty Publications

This paper describes a system that leads us to believe in the feasibility of constructing natural spoken dialogue systems in task-oriented domains. It specifically addresses the issue of robust interpretation of speech in the presence of recognition errors. Robustness is achieved by a combination of statistical error post-correction, syntactically- and semantically-driven robust parsing, and extensive use of the dialogue context. We present an evaluation of the system using time-to-completion and the quality of the final solution that suggests that most native speakers of English can use the system successfully with virtually no training.

Heterogeneous Radial Basis Function Networks, Tony R. Martinez, D. Randall Wilson

Faculty Publications

Radial Basis Function (RBF) networks typically use a distance function designed for numeric attributes, such as Euclidean or city-block distance. This paper presents a heterogeneous distance function which is appropriate for applications with symbolic attributes, numeric attributes, or both. Empirical results on 30 data sets indicate that the heterogeneous distance metric yields significantly improved generalization accuracy over Euclidean distance in most cases involving symbolic attributes.

Smith On Krauss, 'The Physics Of Star Trek', Anne Collins Smith

Faculty Publications

Review of Lawrence M. Krauss.The Physics of Star Trek. New York: Basic Books, 1995. xvi + 188 pp. $20.00(cloth), ISBN 978-0-465-00559-8.

Reviewed by Anne Collins Smith (Austin Community College) Published on H-PCAACA (May, 1996)

A Brief Introduction To Formal Methods, Paul E. Black, Kelly M. Hall, Michael D. Jones, Trent N. Larson, Phillip J. Windley

Faculty Publications

As hardware designs grow in size and complexity, current design methods are proving less adequate. Current methods for specification, design, and test are typically empirical or informal, that is, they are based on experience and argument. Formal methods are solidly based on mathematical logic systems and precise rules of inference. Formal methods offer a discipline which complements current methods so designers can successfully meet the demand for high performance systems. Formal methods covers a broad and diverse set of techniques aimed at improving computer correctness. This paper explains the role of specifications and implementation models in formal methods, and different …

Changing Source Characteristics During Multifragment Decay, T. M. Hamilton, E. Cornell, D. Fox, Y. Lou, R. T. De Souza, M. J. Huang, W. C. Hsi, C. Schwarz, C. Williams, D. R. Bowman, J. Dinius, C. K. Gelbke, T. Glasmacher, D. O. Handzy, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, L. Phair, M. B. Tsang, G. Vanburen, R. J. Charity, L. G. Sobotka, A. A. Sonzogni, D. Prindle

Faculty Publications

The spatial-temporal extent of the emitting system for central collisions in Kr84 + Au197 at E/A = 35, 55, and 70 MeV is probed using fragment-fragment velocity correlation functions. Selection on fragment pairs of high velocity yields a stronger fragment-fragment Coulomb interaction than for inclusive fragment pairs. This result is consistent with fragment emission from a source of decreased spatial-temporal extent. The universality of this association and the effect of different selection criteria are explored. The sensitivity of the spatial-temporal extent deduced by the correlation function technique to measurement uncertainties, assumed source characteristics, and rotational effects is assessed.

Error Correction Via A Post-Processor For Continuous Speech Recognition, Eric K. Ringger, James F. Allen

Faculty Publications

This paper presents a new technique for overcoming several types of speech recognition errors by post-processing the output of a continuous speech recognizer. The post-processor output contains fewer errors, thereby making interpretation by higher-level modules, such as a parser, in a speech understanding system more reliable. The primary advantage to the post-processing approach over existing approaches for overcoming SR errors lies in its abilityto introduce options that are not available in the SR module’s output. This work provides evidence for the claim that a modern continuous speech recognizer can be used successfully in “black-box” fashion for robustly interpreting spontaneous utterances …

Simulations Of Electrostatic Modes Of Non-Neutral Plasmas With Small Aspect Ratio In A Penning Trap, Grant W. Mason, Ross L. Spencer, Jonathan A. Bennett

Faculty Publications

The dependence on induced charge, experimental geometry, and temperature of electrostatic modes in very low aspect ratio non-neutral plasmas in a Penning trap is considered. The modes are of interest as non-destructive diagnostics of the shape of the plasmas. These investigations include equilibrium calculations of plasma shapes and profiles at finite temperature and particle-in-cell simulations of axisymmetric modes. The results of the simulations are compared to the zero-temperature theory by Dubin [Phys. Rev. Lett. 66, 2076 (1991)] taken to first-order in the aspect ratio and to experimental measurements by Weimer et al. [Phys. Rev. A 49, 3842 (1994)]. In general, …

The Advanced Glycation End Product, NE-(Carboxymethyl)Lysine, Is A Product Of Both Lipid Peroxidation And Glycoxidation Reactions, Min-Xin Fu, Jesus R. Requena, Alicia J. Jenkins, Timothy J. Lyons, John W. Baynes, Suzanne R. Thorpe

Faculty Publications

Nepsilon-(Carboxymethyl)lysine (CML) is an advanced glycation end product formed on protein by combined nonenzymatic glycation and oxidation (glycoxidation) reactions. We now report that CML is also formed during metal-catalyzed oxidation of polyunsaturated fatty acids in the presence of protein. During copper-catalyzed oxidation in vitro, the CML content of low density lipoprotein increased in concert with conjugated dienes but was independent of the presence of the Amadori compound, fructoselysine, on the protein. CML was also formed in a time-dependent manner in RNase incubated under aerobic conditions in phosphate buffer containing arachidonate or linoleate; only trace amounts of CML were formed from …

Circumstantial Evidence For A Critical Behavior In Peripheral Au+Au Collisions At 35 Mev/Nucleon, P. F. Mastinu, M. Belkacem, M. D'Agostino, M. Bruno, P. M. Milazzo, G. Vannini, D. R. Bowman, N. Colonna, J. D. Dinius, A. Ferrero, M. L. Fiandri, C. K. Gelbke, T. Glasmacher, F. Gramegna, D. O. Handzy, D. Horn, W. C. Hsi, M. Huang, I. Iori, G. J. Kunde, M. A. Lisa, W. G. Lynch, G. V. Margagliotti, C. P. Montoya, A. Moroni, Graham F. Peaslee, F. Petruzzelli, R. Rui, C. Schwarz, M. B. Tsang, C. Williams, V. Latora, A. Bonasera

Faculty Publications

The fragmentation resulting from peripheral Au+Au collisions at an incident energy of E=35MeV/nucleon is investigated. A power-law charge distribution, A−τ with τ≈2.2, and an intermittency signal are observed for events selected in the region of the Campi scatter plot where “critical” behavior is expected.

Compressing Semi-Structured Text Using Hierarchical Phrase Identifications, Dan R. Olsen Jr., Craig G. Nevill-Manning, Ian H. Witten

Faculty Publications

The structure of this paper is as follows. We begin by identifying some characteristics of semi-structured text that have special relevance to data compression. We then give a brief account of a particular large textual database, and describe a compression scheme that exploits its structure. In addition to providing compression, the system gives some insight into the structure of the database. Finally we show how the hierarchical grammar can be generalized, first manually and then automatically, to yield further improvements in compression performance.

Squeeze-Out Of Nuclear Matter In Au + Au Collisions, M. B. Tsang, P. Danielewicz, W. C. Hsi, M. Huang, W. G. Lynch, D. R. Bowman, C. K. Gelbke, M. A. Lisa, Graham F. Peaslee, R. J. Charity, L. G. Sobotka, M. L. Begemann-Blaich, F. Cosmo, A. Ferrero, J. Hubele, G. Imme, I. Iori, J. Kempter, P. Kruetz, G. J. Kunde, W. D. Kunze, V. Lindenstruth, U. Lynen, M. Mang, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilvie, J. Pochodzalla, G. Raciti, F. Rosenberger, T. Rubehn, H. Sann, R. Scardaoni, A. Schüttauf, C. Schwarz, W. Seidel

Faculty Publications

Emission of charged particles from a compressed reaction zone is studied for Au197+197Au collisions at E/A=100, 250, and 400 MeV. Using a modified coalescence invariant weighting, squeeze-out ratios are determined and compared to predictions of cascade and BUU transport-model calculations.