Physical Sciences and Mathematics Commons^™

Markov Chains And Dynamic Geometry Of Polygons, Jiu Ding, L. Richard Hitt, Xin-Min Zhang

Faculty Publications

In this paper we construct sequences of polygons from a given n-sided cyclic polygon by iterated procedures and study the limiting behaviors of these sequences in terms of non-negative matrices and Markov chains. (C) 2003 Elsevier Science Inc. All rights reserved.

Observation Of And Model For Nonlinear Mode Conversion In A Non-Neutral Plasma, Grant W. Hart, Bryan G. Peterson, Ross L. Spencer

Faculty Publications

The nonlinear interaction of the two lowest Trivelpiece-Gould modes in a non-neutral plasma has been observed. Because of coupling in the nonlinear terms of the continuity and momentum equations, the two modes can exchange energy and convert one to the other. This can be modeled using the cold fluid equations and the averaging method. Experimentally, this process always stops with the lower frequency mode dominating the final state. Numerical integration of the model suggests that this occurs because the higher frequency mode is more strongly damped than the lower frequency mode.

Focusing Of Spin Polarization In Semiconductors By Inhomogeneous Doping, Yuriy V. Pershin Dr, Vladimir Privman

Faculty Publications

We study the evolution and distribution of nonequilibrium electron spin polarization in n-type semiconductors within the two-component drift-diffusion model in an applied electric field. Propagation of spin-polarized electrons through a boundary between two semiconductor regions with different doping levels is considered.We assume that inhomogeneous spin polarization is created locally and driven through the boundary by the electric field.We show that an initially created narrow region of spin polarization can be further compressed and amplified near the boundary. Since the boundary involves variation of doping but no real interface between two semiconductor materials, no significant spin polarization loss is expected. …

Minimal Graphs In R3 Over Convex Domains, Michael Dorff

Faculty Publications

Krust established that all conjugate and associate surfaces of a minimal graph over a convex domain are also graphs. Using a convolution theorem from the theory of harmonic univalent mappings, we generalize Krust's theorem to include the family of convolution surfaces which are generated by taking the Hadamard product or convolution of mappings. Since this convolution involves convex univalent analytic mappings, this family of convolution surfaces is much larger than just the family of associated surfaces. Also, this generalization guarantees that all the resulting surfaces are over close-toconvex domains. In particular, all the associate surfaces and certain Goursat transformation surfaces …

The Topology Of Hyperbolic Attractors On Compact Surfaces, Todd L. Fisher

Faculty Publications

Suppose M is a compact surface and M is a nontrivial mixing hyperbolic attractor for some f 2 Diff(M). We show that if is a hyperbolic set for some g 2 Diff(M), then is a nontrivial mixing hyperbolic attractor or repeller for g.

A Self-Adapting Healthcare Information Infrastructure Using Mobile Computing Devices, James K. Archibald, Eric S. Hall, Charles D. Knutson, David K. Vawdrey

Faculty Publications

Despite recent improvements in the gathering and sharing of patient medical information among healthcare providers, there remains a gap in the electronic medical record infrastructure. Patient data is not available in some situations, either because the infrastructure is inaccessible (as in a natural disaster) or because there is no way to link the patient to the infrastructure (e.g., the patient cannot supply necessary identification information). This paper describes the Poket Doktor System, an architecture that allows an individual to carry personal electronic medical information on a wireless handheld device such as a smart card, cell phone, or PDA. Medical workers …

Bis[Μ-1,2-Bis(2-Pyridyl)Ethyne-K2N:N']Bis[Aquadinitratocadmium(Ii)], Badruz Zaman Md., Matthew J. Davis, Mark D. Smith, Hans Conrad Zur Loye

Faculty Publications

Two twisted 1,2-bis(2-pyridyl)ethyne ligands bridge two Cd²⁺ centers in the C₂-symmetric title complex, [Cd₂(NO₃)₄(-C₁₂H₈N₂)₂(H₂O)₂]. The bridging ligands arch across one another creating a `zigzag loop' molecular geometry. Two nitrate ions and a water molecule complete the irregular seven-coordinate Cd-atom environment. The dihedral angles between the equivalent pyridyl ring planes of the two independent ligands are 67.2 (1)°. O_water-HO_nitrate hydrogen bonding creates two-dimensional layers parallel to the ab plane.

Formula: [Cd₂(NO₃)₄(C …

Links Between Snow Cover, Surface Skin Temperature, And Rainfall Variability In The North American Monsoon System, Toshi Matsui, Venkataraman Lakshmi, Eric Small

Faculty Publications

The influence of land–atmosphere interactions on the variability of the North American monsoon system(NAMS) is investigated using the Television Infrared Observation Satellite (TIROS) Operational Vertical Sounder(TOVS) Pathfinder, the Climate Prediction Center (CPC) gauge precipitation, and observed snow water equivalent(SWE). Three hypotheses are tested regarding the connection between land surface variables and precipitationin the NAMS region. First, there is a weak negative correlation between 1 April SWE and subsequent surfacetemperature in the southern Rocky Mountains (SRM) region. However, this connection persists only until Juneand, therefore, cannot directly influence monsoon rainfall in July and August. Second, there is a negativecorrelation between SRM …

Dynamic Joint Action Perception For Q-Learning Agents, Nancy Fulda, Dan A. Ventura

Faculty Publications

Q-learning is a reinforcement learning algorithm that learns expected utilities for state-action transitions through successive interactions with the environment. The algorithm's simplicity as well as its convergence properties have made it a popular algorithm for study. However, its non-parametric representation of utilities limits its effectiveness in environments with large amounts of perceptual input. For example, in multiagent systems, each agent may need to consider the action selections of its counterparts in order to learn effective behaviors. This creates a joint action space which grows exponentially with the number of agents in the system. In such situations, the Q-learning algorithm quickly …

Knot Intervals And Multi-Degree Splines, Thomas W. Sederberg, Jianmin Zheng, Xiaowen Song

Faculty Publications

This paper studies the merits of using knot interval notation for B-spline curves, and presents formulae in terms of knot intervals for common B-spline operations such as knot insertion, differentiation, and degree elevation. Using knot interval notation, the paper introduces MD-splines, which are B-spline-like curves that are comprised of polynomial segments of various degrees (MD stands for \multi-degree"). MD-splines are a generalization of B-spline curves in that if all curve segments in an MD-spline have the same degree, it reduces to a B-spline curve. The paper focuses on MD-splines of degree 1, 2, and 3, as well as degree 1 …

A Noise Filtering Method Using Neural Networks, Tony R. Martinez, Xinchuan Zeng

Faculty Publications

During the data collecting and labeling process it is possible for noise to be introduced into a data set. As a result, the quality of the data set degrades and experiments and inferences derived from the data set become less reliable. In this paper we present an algorithm, called ANR (automatic noise reduction), as a filtering mechanism to identify and remove noisy data items whose classes have been mislabeled. The underlying mechanism behind ANR is based on a framework of multi-layer artificial neural networks. ANR assigns each data item a soft class label in the form of a class probability …

Simplifying Ocr Neural Networks With Oracle Learning, Tony R. Martinez, Joshua Menke

Faculty Publications

Often the best model to solve a real world problem is relatively complex. The following presents oracle learning, a method using a larger model as an oracle to train a smaller model on unlabeled data in order to obtain (1) a simpler acceptable model and (2) improved results over standard training methods on a similarly sized smaller model. In particular, this paper looks at oracle learning as applied to multi-layer perceptrons trained using standard backpropagation. For optical character recognition, oracle learning results in an 11.40% average decrease in error over direct training while maintaining 98.95% of the initial oracle accuracy.

Leading Proton Production In E + P Collisions At Hera, S. Chekanov, D. Krakauer, J. H. Loizides, S. Magill, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Anzivino, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, M. Chiarini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Levi, A. Margotti, T. Massam, R. Nania, C. Nemoz, F. Palmonari

Faculty Publications

Events with a final-state proton carrying a large fraction of the proton beam momentum, x L >0.6, and the square of the transverse momentum p T2

Scaling Violations And Determination Of ΑS From Jet Production In Γp Interactions At Hera, S. Chekanov, D. Krakauer, J. H. Loizides, S. Magill, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, A. Margotti, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli, A. Zichichi, G. Aghuzumtsyan, D. Bartsch

Faculty Publications

Differential cross sections for jet photoproduction in the reaction ep → e jet X have been measured with the ZEUS detector at HERA using 82.2 pb-1 of integrated luminosity. Inclusive jet cross sections are presented as a function of the jet transverse energy, ETjet, for jets with ETjet > 17 GeV and pseudorapidity -1 <ηjet >

Bacteriological Water Quality Of Forested And Pastured Streams Receiving Land-Applied Poultry Litter, Matthew W. Mcbroom, Chang Mingteh, Charles Wells

Faculty Publications

Poultry production is a growing industry in East Texas, generating about 360,000 m tons of broiler litter each year as a by-product for application on pasturelands. Grab samples of fecal coliform (FC) and fecal streptococcus (FS) were collected monthly between March and December 1996 and FC and E-coli samples were collected weekly between July and October 2001 at six sites on the Waffelo and Terrapin Creeks in Nacogdoches County, Texas to assess possible impacts of poultry litter application on bacterial water quality. Sites were grouped by three pairs with each pair consisting of one upstream site in predominantly forested area …

Mercury Concentrations In Streams Of East Texas, Mingteh Chang, Mark C. Cochran, R. Scott Beasley, Matthew W. Mcbroom

Faculty Publications

Recent studies on potential mercury (Hg) contamination of fish from East Texas lakes and waterways have caused concern about mercury levels in East Texas waters. Historical records of Hg concentrations in 33 East Texas streams showed that median concentrations for each stream segment were no different than other U.S. streams. All the means and medians for stream segments having at least 20 recorded measurements were less than Texas (2.4 µg/L) water quality standards. Water samples collected in December 1995 and March 1996 from 6 different stream sites in Nacogdoches County had concentrations similar to historical records. Due to biological magnification, …

Planning Your Way To A More Usable Web Site, Pamela Gore, Sandra Hirsh

Faculty Publications

Planning for long-term periodic usability assessment is therefore as important as adding regularly fresh content and tracking usage. Fortunately, usability assessments need not be time consuming or expensive, unless your site is large and complex and you want to test it thoroughly each time. In a practical sense, usability assessment can reveal problems in the design, navigation, layout, or labeling that prevent users from finding what they need quickly. After analyzing your environment and setting the stage for ongoing usability assessment, it is time to develop the usability assessment plan, which will serve as the blueprint for usability assessment activities …

Decay Of Trapped-Particle Asymmetry Modes In Non-Neutral Plasmas In A Malmberg-Penning Trap, Grant W. Mason

Faculty Publications

The mechanism for the strong damping of diocotron-like azimuthal trapped-particle asymmetry modes in a Malmberg-Penning trap is investigated with a detailed three-dimensional particle-in-cell computer simulation. The m = 1,kzis not equal to 0 modes are created by a voltage squeeze from a mid-detector ring followed by a displacement of trapped particles in opposite directions on either side of the ring. The voltage squeeze creates a population of particles confined to half the trap length (trapped) and a population of particles that move longitudinally along the full length of the cylinder (untrapped). The damping of the modes is found to be …

Enabling Remote Access To Personal Electronic Medical Records, James K. Archibald, Eric S. Hall, Charles D. Knutson, David K. Vawdrey

Faculty Publications

Millions of people suffer from medical conditions that should be made known to healthcare practitioners prior to treatment. Paramedics and emergency room doctors cannot provide optimal care without sufficient knowledge of a patient’s medical history. Lacking patient information such as allergies, current prescriptions, and preexisting conditions, medical professionals are often forced to either delay treatment or rely on instincts. Medical mistakes in situations like these kill thousands of people and cost an estimated US$37 billion each year in the United States [1]. With the advent of electronic medical records (EMRs), patient information can be stored in computer databases at hospitals …

Concurrently Learning Neural Nets: Encouraging Optimal Behavior In Cooperative Reinforcement Learning Systems, Nancy Fulda, Dan A. Ventura

Faculty Publications

Reinforcement learning agents interacting in a common environment often fail to converge to optimal system behaviors even when the individual goals of the agents are fully compatible. Claus and Boutilier have demonstrated that the use of joint action learning helps to overcome these difficulties for Q-learning systems. This paper studies an application of joint action learning to systems of neural networks. Neural networks are a desirable candidate for such augmentations for two reasons: (1) they may be able to generalize more effectively than Q-learners, and (2) the network topology used may improve the scalability of joint action learning to systems …

Model-Based Human-Centered Task Automation: A Case Study In Acc System Design, Michael A. Goodrich, Erwin R. Boer

Faculty Publications

Engineers, business managers, and governments are increasingly aware of the importance and difficulty of integrating technology and humans. The presence of technology can enhance human comfort, efficiency, and safety, but the absence of human factors analysis can lead to uncomfortable, inefficient, and unsafe systems. Systematic human-centered design requires a basic understanding of how humans generate and manage tasks. A very useful model of human behavior generation can be obtained by recognizing the task-specific role of mental models in not only guiding execution of skills but also managing initiation and termination of these skills. By identifying the human operator’s mental models …

Sr3Mgpto6, Mark D. Smith, Hans Conrad Zur Loye

Faculty Publications

Single crystals of the mixed alkaline earth platinate, tristrontium magnesium platinum hexaoxide, Sr₃MgPtO₆, were grown from a KOH flux at 1273 K. The compound adopts the rhombohedral K₄CdCl₆ structure type, featuring chains of face-shared, distorted MgO₆ trigonal prisms (Mg site symmetry 32) and PtO₆ octahedra (Pt site symmetry ) surrounded by columns of Sr²⁺ ions (Sr site symmetry 2).

Measurement Of High-Q2 E- P Neutral Current Cross Sections At Hera And The Extraction Of Xf3: The Zeus Collaboration, S. Chekanov, D. Krakauer, S. Magill, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, A. Margotti, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli, A. Zichichi, G. Aghuzumtsyan, D. Bartsch, I. Brock

Faculty Publications

Cross sections for e- p neutral current deep inelastic scattering have been measured at a centre-of-mass energy of 318 GeV using an integrated luminosity of 15.9 pb-1 collected with the ZEUS detector at HERA. Results on the double-differential cross-section d2σ/dx dQ2 in the range 185 < Q2 < 50 000 GeV2 and 0.0037 < x < 0.75, as well as the single-differential cross-sections dσ/dQ2, dσ/dx and dσ/dy for Q2 > 200GeV2, are presented. To study the effect of Z-boson exchange, dσ/dx has also been measured for Q2 > 10 000 GeV2. The structure function xF3 has been extracted by combining the e-p results presented here with the recent ZEUS measurements of e+ p neutral current deep inelastic scattering. All results agree well with the predictions of …

Search For Single-Top Production In Ep Collisions At Hera, S. Chekanov, M. Derrick, D. Krakauer, J. H. Loizides, S. Magill, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, A. Margotti, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli, A. Zichichi, G. Aghuzumtsyan

Faculty Publications

A search for single-top production, ep → et X, has been made with the ZEUS detector at HERA using an integrated luminosity of 130.1 pb-1. Events from both the leptonic and hadronic decay channels of the W boson resulting from the decay of the top quark were sought. For the leptonic mode, the search was made for events with isolated high-energy leptons and significant missing transverse momentum. For the hadronic decay mode, three-jet events in which two of the jets had an invariant mass consistent with that of the W were selected. No evidence for top production was found. The …

Eocene To Miocene Magnetostratigraphy, Biostratigraphy, And Chemostratigraphy At Odp Site 1090 (Sub-Antarctic South Atlantic), J E T Channell, S Galeotti, Ellen E. Martin, K Billups, Howie Scher, J S. Stoner

Faculty Publications

At Ocean Drilling Program (ODP) Site 1090 (lat 42854.89S, long 8854.09E) locatedin a water depth of 3702 m on the Agulhas Ridge in the sub-Antarctic South Atlantic, ~300 m of middle Eocene to middle Miocenesediments were recovered with the advancedpiston corer (APC) and the extendedcore barrel (XCB). U-channel samplesfrom the 70–230 meters composite depth(mcd) interval provide a magnetic polaritystratigraphy that is extended to 380 mcd byshipboard whole-core and discrete sampledata. The magnetostratigraphy can be interpretedby the fit of the polarity-zone patternto the geomagnetic polarity time scale(GPTS) augmented by isotope data andbioevents with documented correlation tothe GPTS. Three normal-polarity subchrons(C5Dr.1n, C7Ar.1n, …

Optically Oriented And Detected Electron Spin Resonance In A Lightly Doped N-Gaas Layer, John S. Colton, T. A. Kennedy, A. S. Bracker, D. Gammon, J. B. Miller

Faculty Publications

Spin resonance of localized electrons bound to donors in a specially designed n-GaAs layer has been performed at 236 MHz and 41 mT, using circular polarized light to polarize the electrons and photoluminescence to detect the electronic polarization. The polarization was diminished under the resonance condition. The electronic g factor obtained by this measurement is - 0.41 ± 0.01. The resonance linewidth of 2 mT corresponds to a spin lifetime of 28 ns. In order to observe the electronic spin resonance, nuclear effects were eliminated by application of rf fields to simultaneously resonate the nuclear spins.

Measurement Of Subjet Multiplicities In Neutral Current Deep Inelastic Scattering At Hera And Determination Of ΑS, S. Chekanov, D. Krakauer, J. H. Loizides, S. Magill, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, A. Margotti, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli, A. Zichichi, G. Aghuzumtsyan, D. Bartsch

Faculty Publications

The subjet multiplicity has been measured in neutral current e+p interactions at Q2 > 125 GeV2 with the ZEUS detector at HERA using an integrated luminosity of 38.6 pb-1. Jets were identified in the laboratory frame using the longitudinally invariant kT cluster algorithm. The number of jet-like substructures within jets, known as the subjet multiplicity, is defined as the number of clusters resolved in a jet by reapplying the jet algorithm at a smaller resolution scale ycut. Measurements of the mean subjet multiplicity, (nsbj), for jets with transverse energies ET,jet > 15 GeV are presented. Next-to-leading-order perturbative QCD calculations describe the measurements …

Search And Recovery Of The Space Shuttle Columbia: A Geospatial 1st Responder Perspective, Jeffrey M. Williams

Faculty Publications

A first person account of the Texas geospatial volunteers and their efforts to recover the remains of the Space Shuttle Columbia and her crew lost over eastern Texas and western Louisiana on February 1st, 2003.

A High Throughput Method For The Conversion Of Co2 Obtained From Biochemical Samples To Graphite In Septa-Sealed Vials For Quantification Of 14c Samples Via Accelerator Mass Spectrometry, Ted J. Ognibene, Graham Bench, John S. Vogel, Graham F. Peaslee, Steve Murov

Faculty Publications

The growth of accelerator mass spectrometry as a tool for quantitative isotope ratio analysis in the biosciences necessitates high-throughput sample preparation. A method has been developed to convert CO2 obtained from carbonaceous samples to solid graphite for highly sensitive and precise 14C quantification. Septa-sealed vials are used along with commercially available disposable materials, eliminating sample cross contamination, minimizing complex handling, and keeping per sample costs low. Samples containing between 0.25 and 10 mg of total carbon can be reduced to graphite in 4 h in routine operation. Approximately 150 samples per 8-h day can be prepared by a single technician.

Valuation Of Continuous And Intermittent Phragmites Control, R. Eugene Turner, R. S. Warren

Faculty Publications

Quantifying the relative value of Phragmites australis and Spartina alterniflora habitat is important to evaluate the benefits and risks of different attempts to address Phragmites expansion on the U.S. eastern seaboard. Two contrasting approaches commonly used to restore tidal marsh habitats invaded by Phragmites communities involve spraying Phragmites with herbicide only when its coverage of a particular marsh area is near or close to 100%. Alternatively, after the first application, herbicide is annually applied on any surviving patches of Phragmites present in a mosaic of other marsh vegetation. A model is introduced to evaluate the relative habitat value of these …