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Articles 2701 - 2730 of 3789

Full-Text Articles in Physical Sciences and Mathematics

Time-Of-Flight Emission Profiles Of The Entire Plume Using Fast Imaging During Pulsed Laser Deposition Of Yba2Cu3O7−X, Carl J. Druffner, Glen P. Perram, Rand R. Biggers Sep 2005

Time-Of-Flight Emission Profiles Of The Entire Plume Using Fast Imaging During Pulsed Laser Deposition Of Yba2Cu3O7−X, Carl J. Druffner, Glen P. Perram, Rand R. Biggers

Faculty Publications

Emission time-of-flight (TOF) profiles have been obtained using gated imagery to further the process control during the pulsed laser deposition of the high temperature superconductor, YBa2Cu3O7−x⁠. An intensified charge coupled device array was used to obtain a sequence of plume images at 10ns temporal resolution and 0.2mm spatial resolution. Plume imagery is transformed to TOF profiles and pulse-to-pulse variations removed using physically based smoothing techniques. Comparison with non-imaging sensors establishes excellent agreement, with systematic uncertainties in streaming speed and temperatures of less than 15% and 8%, respectively. The resulting streaming speeds of 0.4–1.2×10 …

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Measurement Of Inelastic J/Ψ Production In Deep Inelastic Scattering At Hera, S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, A. G. Yagües Molina, 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, A. Montanari, R. Nania, F. Palmonari, A. Pesci, A. Polini Sep 2005

Measurement Of Inelastic J/Ψ Production In Deep Inelastic Scattering At Hera, S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, A. G. Yagües Molina, 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, A. Montanari, R. Nania, F. Palmonari, A. Pesci, A. Polini

Faculty Publications

The inelastic production of J/ψ mesons in ep collisions has been studied with the ZEUS detector at HERA using an integrated luminosity of 109 pb-1. The J/ψ mesons were identified using the decay channel J/ψ → μ+μ- The measurements were performed in the kinematic range 2 < Q2 < 80 GeV2, 50 < W < 250 GeV, 0.2 < z < 0.9 and -1.6 < Ylab < 1.3, where Q2 is the virtuality of the exchanged photon, W is the photon-proton centre-of-mass energy, z is the fraction of the photon energy carried by the J/ψ meson in the proton rest frame and Ylab is the rapidity of the J/ψ in the laboratory frame. The measured cross sections are compared to theoretical predictions within the non-relativistic QCD framework including colour-singlet and colour-octet contributions, as well as to predictions based on the κT-factorisation approach. Calculations of the colour-singlet process generally agree with the data, whereas inclusion of colour-octet terms spoils this agreement. © Springer-Verlag/Società Italiana di Fisica 2005.

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Studies In The Dynamics Of Economic Systems, Christophe G. Giraud-Carrier, Kevin Seppi, Nghia Tran, Sean C. Warnick, W. Samuel Weyerman, R. Johnson Aug 2005

Studies In The Dynamics Of Economic Systems, Christophe G. Giraud-Carrier, Kevin Seppi, Nghia Tran, Sean C. Warnick, W. Samuel Weyerman, R. Johnson

Faculty Publications

This paper demonstrates the utility of systems and control theory in the analysis of economic systems. Two applications demonstrate how the analysis of simple dynamic models sheds light on important practical problems. The first problem considers the design of a retail laboratory, where the small gain theorem enables the falsification of pricing policies. The second problem explores industrial organization using the equilibria of profit-maximizing dynamics to quantify the percentage of a firm’s profits due strictly to the cooperative effects among its products. This ”Value of Cooperation” suggests an important measure for both organizational and antitrust applications.

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Tris(1,10-Phenanthroline)Cobalt(Ii) Triiodide, Meredith A. Tershany, Andrea M. Goforth, Mark D. Smith, Leroy Peterson Jr., Hans-Conrad Zur Loye Aug 2005

Tris(1,10-Phenanthroline)Cobalt(Ii) Triiodide, Meredith A. Tershany, Andrea M. Goforth, Mark D. Smith, Leroy Peterson Jr., Hans-Conrad Zur Loye

Faculty Publications

The asymmetric unit of the title compound, [Co(C12H8N2)3](I3)2, contains one [Co(1,10-phenanthroline)3]2+ cation, half each of two centrosymmetric triiodide anions, and one complete triiodide anion. The title compound was synthesized solvothermally from Co(NO3)2, 1,10-phenanthroline, and SnI2, where the SnI2 reagent serves only as a source of I atoms.

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Task Similarity Measures For Transfer In Reinforcement Learning Task Libraries, James Carroll, Kevin Seppi Aug 2005

Task Similarity Measures For Transfer In Reinforcement Learning Task Libraries, James Carroll, Kevin Seppi

Faculty Publications

Recent research in task transfer and task clustering has necessitated the need for task similarity measures in reinforcement learning. Determining task similarity is necessary for selective transfer where only information from relevant tasks and portions of a task are transferred. Which task similarity measure to use is not immediately obvious. It can be shown that no single task similarity measure is uniformly superior. The optimal task similarity measure is dependent upon the task transfer method being employed. We define similarity in terms of tasks, and propose several possible task similarity measures, dT, dp, dQ, and dR which are based on …

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Edge Inference For Image Interpolation, Bryan S. Morse, Neil Toronto, Dan A. Ventura Aug 2005

Edge Inference For Image Interpolation, Bryan S. Morse, Neil Toronto, Dan A. Ventura

Faculty Publications

Image interpolation algorithms try to fit a function to a matrix of samples in a "natural-looking" way. This paper presents edge inference, an algorithm that does this by mixing neural network regression with standard image interpolation techniques. Results on gray level images are presented, and it is demonstrated that edge inference is capable of producing sharp, natural-looking results. A technique for reintroducing noise is given, and it is shown that, with noise added using a bicubic interpolant, edge inference can be regarded as a generalization of bicubic interpolation. Extension into RGB color space and additional applications of the algorithm are …

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A Comparison Of Generalizability For Anomaly Detection, Gilbert L. Peterson, Robert F. Mills, Brent T. Mcbride, Wesley T. Allred Aug 2005

A Comparison Of Generalizability For Anomaly Detection, Gilbert L. Peterson, Robert F. Mills, Brent T. Mcbride, Wesley T. Allred

Faculty Publications

In security-related areas there is concern over the novel “zeroday” attack that penetrates system defenses and wreaks havoc. The best methods for countering these threats are recognizing “non-self” as in an Artificial Immune System or recognizing “self” through clustering. For either case, the concern remains that something that looks similar to self could be missed. Given this situation one could logically assume that a tighter fit to self rather than generalizability is important for false positive reduction in this type of learning problem. This article shows that a tight fit, although important, does not supersede having some model generality. This …

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Relative Charge Transfer Cross Section From Rb(4d), M.H. Shah, H.A. Camp, M.L. Trachy, X. Fléchard, M.A. Gearba, H. Nguyen, R. Brédy, S.R. Lundeen, B.D. Depaola Aug 2005

Relative Charge Transfer Cross Section From Rb(4d), M.H. Shah, H.A. Camp, M.L. Trachy, X. Fléchard, M.A. Gearba, H. Nguyen, R. Brédy, S.R. Lundeen, B.D. Depaola

Faculty Publications

Relative charge transfer cross section measurements for the excited state Rb (4d) with 7 keV Na+ is reported. The specific channels reported as Na+ + Rb (4d5/2) → Na (nl) + Rb+, where the dominant transfer cross sections channels were nl = 3d and 4s. Using a combination of a magneto-optical trap and recoil ion momentum spectroscopy (MOTRIMS methodology), the cross sections were measured relative to the previously studied Na+ + Rb (5s, 5p) systems at the same collision energy.

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A Modified Poisson–Boltzmann Analysis Of The Capacitance Behavior Of The Electric Double Layer At Low Temperatures, Douglas Henderson, L. B. Bhuiyan, C. W. Outhwaite Jul 2005

A Modified Poisson–Boltzmann Analysis Of The Capacitance Behavior Of The Electric Double Layer At Low Temperatures, Douglas Henderson, L. B. Bhuiyan, C. W. Outhwaite

Faculty Publications

The modified Poisson–Boltzmann theory is used to analyze the anomalous behavior of the electric double layer capacitance for small surface charge at low temperatures and densities. Good agreement is found with simulation and recent density-functional theory results. Negative adsorption is also found in line with theory and simulation. An unsatisfactory feature is the relatively poor structure in this region due to the inherent approximations in the theory. This feature is unimportant in relation to the capacitance results but has implications when calculating adsorption properties.

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Hard-Sphere Radial Distribution Function Again, Andrij Trokhymchuk, Douglas Henderson, Ivo Nezbeda, Jan Jirsak Jul 2005

Hard-Sphere Radial Distribution Function Again, Andrij Trokhymchuk, Douglas Henderson, Ivo Nezbeda, Jan Jirsak

Faculty Publications

A theoretically based closed-form analytical equation for the radial distribution function, g(r), of a fluid of hard spheres is presented and used to obtain an accurate analytic representation. The method makes use of an analytic expression for the short- and long-range behaviors of g(r), both obtained from the Percus-Yevick equation, in combination with the thermodynamic consistency constraint. Physical arguments then leave only three parameters in the equation of g(r) that are to be solved numerically, whereas all remaining ones are taken from the analytical solution of the Percus-Yevick equation.

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Tris(Ethylenediamine)Cobalt(Iii) Nonaiododibismuthate, Andrea M. Goforth, Rachael E. Hipp, Mark D. Smith, Leroy Peterson Jr., Hans-Conrad Zur Loye Jul 2005

Tris(Ethylenediamine)Cobalt(Iii) Nonaiododibismuthate, Andrea M. Goforth, Rachael E. Hipp, Mark D. Smith, Leroy Peterson Jr., Hans-Conrad Zur Loye

Faculty Publications

The asymmetric unit of the title compound, [Co(C2H8N2)3][Bi2I9], crystallizes in the orthorhombic space group Cmc21. The asymmetric unit contains half of a [Co(en)3]3+ cation (en is ethylenediamine) and half of a [Bi2I9]3- anion. Both species are located on mirror planes, requiring the [Co(en)3]3+ cation to be present as a statistically disordered mixture of both enantiomeric forms. Crystals were grown solvothermally from an ethanol-water solvent mixture using rac-[Co(en)3]I3 and bismuth triiodide …

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Exclusive Electroproduction Of Φ Mesons At Hera, S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, A. G. Yagües Molina, 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. Guisti, G. Iacobucci, A. Margotti, A. Montanari, R. Nania, F. Palmonari, A. Pesci, A. Polini Jul 2005

Exclusive Electroproduction Of Φ Mesons At Hera, S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, A. G. Yagües Molina, 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. Guisti, G. Iacobucci, A. Margotti, A. Montanari, R. Nania, F. Palmonari, A. Pesci, A. Polini

Faculty Publications

Exclusive electroproduction of φ mesons has been studied in e±p collisions at √s = 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 65.1 pb-1. The γ* p cross section is presented in the kinematic range 2 GeV2 < Q2 < 70 GeV2, 35 GeV < W < 145 GeV and t < 0.6 GeV2. The cross sections as functions of Q2, W, t and helicity angle θh are compared to cross sections for other vector mesons. The ratios R of the cross sections for longitudinally and transversely polarized virtual photons are presented as functions of Q2 and W. The data are also compared to predictions from theoretical models. © 2005 Elsevier B.V. All rights reserved.

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Validating Human–Robot Interaction Schemes In Multitasking Environments, Jacob W. Crandall, Michael A. Goodrich, Curtis W. Nielsen, Dan R. Olsen Jr. Jul 2005

Validating Human–Robot Interaction Schemes In Multitasking Environments, Jacob W. Crandall, Michael A. Goodrich, Curtis W. Nielsen, Dan R. Olsen Jr.

Faculty Publications

The ability of robots to autonomously perform tasks is increasing. More autonomy in robots means that the human managing the robot may have available free time. It is desirable to use this free time productively, and a current trend is to use this available free time to manage multiple robots. We present the notion of neglect tolerance as a means for determining how robot autonomy and interface design determine how free time can be used to support multitasking, in general, and multirobot teams, in particular. We use neglect tolerance to 1) identify the maximum number of robots that can be …

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Categorizing And Extracting Information From Multilingual Html Documents, Yiu-Kai D. Ng, Seungjin Lim Jul 2005

Categorizing And Extracting Information From Multilingual Html Documents, Yiu-Kai D. Ng, Seungjin Lim

Faculty Publications

The amount of online information written in different natural languages and the number of non-English speaking Internet users have been increasing tremendously during the past decade. In order to provide high-performance access of multilingual information on the Internet, we have developed a data analysis and querying system (DatAQs) that (i) analyzes, identifies, and categorizes languages used in HTML documents, (ii) extracts information from HTML documents of interest written in different languages, (iii) allows the user to submit queries for retrieving extracted information in the same natural language provided by the query engine of DatAQs using a menu-driven user interface, and …

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Detecting Similar Html Documents Using A Fuzzy Set Information Retrieval Approach, Yiu-Kai D. Ng, Rajiv Yerra Jul 2005

Detecting Similar Html Documents Using A Fuzzy Set Information Retrieval Approach, Yiu-Kai D. Ng, Rajiv Yerra

Faculty Publications

Web documents that are either partially or completely duplicated in content are easily found on the Internet these days. Not only do these documents create redundant information on the Web, which take longer to filter unique information and cause additional storage space, but also they degrade the efficiency of Web information retrieval. In this paper, we present a new approach for detecting similar Web documents, especially HTML documents. Our detection approach determines the odd ratio of any two documents, which makes use of the degrees of resemblance of the documents, and graphically displays the locations of similar (not necessarily the …

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An Nlo Qcd Analysis Of Inclusive Cross-Section And Jet-Production Fata From The Zeus Experiment, S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, A. G. Yagües Molina, 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, A. Montanari, R. Nania, F. Palmonari, A. Pesci, A. Polini Jul 2005

An Nlo Qcd Analysis Of Inclusive Cross-Section And Jet-Production Fata From The Zeus Experiment, S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, N. Pavel, A. G. Yagües Molina, 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, A. Montanari, R. Nania, F. Palmonari, A. Pesci, A. Polini

Faculty Publications

The ZEUS inclusive differential cross-section data from HERA, for charged and neutral current processes taken with e + and e - beams, together with differential cross-section data on inclusive jet production in e + p scattering and dijet production in γp scattering, have been used in a new NLO QCD analysis to extract the parton distribution functions of the proton. The input of jet-production data constrains the gluon and allows an accurate extraction of alpha s(MZ) at NLO; alphas = 0.1183±0.0028(exp.)±0.0008(model). An additional uncertainty from the choice of scales is estimated as ±0.005. This is the first extraction of alphas(MZ) …

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Comparing High-Order Boolean Features, Adam Drake, Dan A. Ventura Jul 2005

Comparing High-Order Boolean Features, Adam Drake, Dan A. Ventura

Faculty Publications

Many learning algorithms attempt, either explicitly or implicitly, to discover useful high-order features. When considering all possible functions that could be encountered, no particular type of high-order feature should be more useful than any other. However, this paper presents arguments and empirical results that suggest that for the learning problems typically encountered in practice, some high-order features may be more useful than others.

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Effectively Using Recurrently-Connected Spiking Neural Networks, Eric Goodman, Dan A. Ventura Jul 2005

Effectively Using Recurrently-Connected Spiking Neural Networks, Eric Goodman, Dan A. Ventura

Faculty Publications

Recurrently-connected spiking neural networks are difficult to use and understand because of the complex nonlinear dynamics of the system. Through empirical studies of spiking networks, we deduce several principles which are critical to success. Network parameters such as synaptic time delays and time constants and the connection probabilities can be adjusted to have a significant impact on accuracy. We show how to adjust these parameters to fit the type of problem.

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Time Invariance And Liquid State Machines, Eric Goodman, Dan A. Ventura Jul 2005

Time Invariance And Liquid State Machines, Eric Goodman, Dan A. Ventura

Faculty Publications

Time invariant recognition of spatiotemporal patterns is a common task of signal processing. Liquid state machines (LSMs) are a paradigm which robustly handle this type of classification. Using an artificial dataset with target pattern lengths ranging from 0.1 to 1.0 seconds, we train an LSM to find the start of the pattern with a mean absolute error of 0.18 seconds. Also, LSMs can be trained to identify spoken digits, 1-9, with an accuracy of 97.6%, even with scaling by factors ranging from 0.5 to 1.5.

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Commutation Relations For Functions Of Operators, Mark K. Transtrum, Jean-Francois S. Van Huele Jun 2005

Commutation Relations For Functions Of Operators, Mark K. Transtrum, Jean-Francois S. Van Huele

Faculty Publications

We derive an expression for the commutator of functions of operators with constant commutations relations in terms of the partial derivatives of these functions. This result extends the well-known commutation relation between one operator and a function of another operator. We discuss the range of applicability of the formula with examples in quantum mechanics

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Microgravity Studies Of Aggregation In Particulate Clouds, Todd B. Sauke, J. R. Marshall, J. N. Cuzzi Jun 2005

Microgravity Studies Of Aggregation In Particulate Clouds, Todd B. Sauke, J. R. Marshall, J. N. Cuzzi

Faculty Publications

Aggregation in clouds of submillimeter quartz and volcanic ash particles was studied in microgravity. Particle clouds generated by pulses of air immediately formed electrostatic filamentary aggregates upon cessation of air turbulence. Manual agitation of experiment chambers produced cm-size loose grain clusters which voraciously scavenged free-floating material in their vicinity. A dipole model accounts for these observations. Experimental results have ramifications for the behavior of natural cloud systems and primary accretion of solids in the early solar nebula.

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An Evolutionary Algorithm To Generate Hyper-Ellipsoid Detectors For Negative Selection, Joseph M. Shapiro, Gary B. Lamont, Gilbert L. Peterson Jun 2005

An Evolutionary Algorithm To Generate Hyper-Ellipsoid Detectors For Negative Selection, Joseph M. Shapiro, Gary B. Lamont, Gilbert L. Peterson

Faculty Publications

This paper introduces hyper-ellipsoids as an improvement to hyper-spheres as intrusion detectors in a negative selection problem within an artificial immune system. Since hyper-spheres are a specialization of hyper-ellipsoids, hyper-ellipsoids retain the benefits of hyper-spheres. However, hyper-ellipsoids are much more flexible, mostly in that they can be stretched and reoriented. The viability of using hyper-ellipsoids is established using several pedagogical problems. We conjecture that fewer hyper-ellipsoids than hyper-spheres are needed to achieve similar coverage of nonself space in a negative selection problem. Experimentation validates this conjecture. In pedagogical benchmark problems, the number of hyper-ellipsoids to achieve good results is significantly …

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Correspondence Expansion For Wide Baseline Stereo, Parris K. Egbert, Kevin L. Steele Jun 2005

Correspondence Expansion For Wide Baseline Stereo, Parris K. Egbert, Kevin L. Steele

Faculty Publications

We present a new method for generating large numbers of accurate point correspondences between two wide baseline images. This is important for structure-from-motion algorithms, which rely on many correct matches to reduce error in the derived geometric structure. Given a small initial correspondence set we iteratively expand the set with nearby points exhibiting strong affine correlation, and then we constrain the set to an epipolar geometry using RANSAC. A key point to our algorithm is to allow a high error tolerance in the constraint, allowing the correspondence set to expand into many areas of an image before applying a lower …

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Active Contours Using A Constraint-Based Implicit Representation, Weiming Liu, Bryan S. Morse, Kalpathi Subramanian, Terry S. Yoo Jun 2005

Active Contours Using A Constraint-Based Implicit Representation, Weiming Liu, Bryan S. Morse, Kalpathi Subramanian, Terry S. Yoo

Faculty Publications

We present a new constraint-based implicit active contour, which shares desirable properties of both parametric and implicit active contours. Like parametric approaches, their representation is compact and can be manipulated interactively. Like other implicit approaches, they can naturally adapt to non-simple topologies. Unlike implicit approaches using level-set methods, representation of the contour does not require a dense mesh. Instead, it is based on specified on-curve and off-curve constraints, which are interpolated using radial basis functions. These constraints are evolved according to specified forces drawn from the relevant literature of both parametric and implicit approaches. This new type of active contour …

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A Scenario-Based Performance Evaluation Of Multicast Routing Protocols For Ad Hoc Networks, Manoj Pandey, Daniel Zappala Jun 2005

A Scenario-Based Performance Evaluation Of Multicast Routing Protocols For Ad Hoc Networks, Manoj Pandey, Daniel Zappala

Faculty Publications

Current ad hoc multicast routing protocols have been designed to build and maintain a tree or mesh in the face of a mobile environment, with fast reaction to network changes in order to minimize packet loss. However, the performance of these protocols has not been adequately examined under realistic scenarios. Existing performance studies generally use a single, simple mobility model, with low density and often very low traffic rates. In this paper we explore the performance of ad hoc multicast routing protocols under scenarios that include realistic mobility patterns, high density and high traffic load. We use these scenarios to …

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Erratum: Computing The M = 1 Diocotron Frequency Via An Equilibrium Calculation In Non-Neutral Plasmas, Ross L. Spencer May 2005

Erratum: Computing The M = 1 Diocotron Frequency Via An Equilibrium Calculation In Non-Neutral Plasmas, Ross L. Spencer

Faculty Publications

Equation 14 in this paper contains errors.

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Spin Photovoltaic Effect In Quantum Wires With Rashba Interaction, Yuriy V. Pershin Dr, Carlo Piermarocchi May 2005

Spin Photovoltaic Effect In Quantum Wires With Rashba Interaction, Yuriy V. Pershin Dr, Carlo Piermarocchi

Faculty Publications

We propose a mechanism for spin-polarized photocurrent generation in quantum wires. The effect is due to the combined effect of Rashba spin-orbit interaction, external magnetic field, and microwave radiation. The time-independent interactions in the wire give rise to a spectrum asymmetry in k space. The microwave radiation induces transitions between spin-splitted subbands, and, due to the peculiar energy dispersion relation, charge and spin currents are generated at zero-bias voltage. We demonstrate that the generation of pure spin currents is possible under an appropriate choice of external control parameters.

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Cyclopropylcarbinyl → Homoallyl-Type Ring Opening Of Ketyl Radical Anions. Structure/Reactivity Relationships And The Contribution Of Solvent/Counterion Reorganization To The Intrinsic Barrier, J. M. Tanko, Jason G. Gillmore, Robert Friedline, M'Hamed Chahma May 2005

Cyclopropylcarbinyl → Homoallyl-Type Ring Opening Of Ketyl Radical Anions. Structure/Reactivity Relationships And The Contribution Of Solvent/Counterion Reorganization To The Intrinsic Barrier, J. M. Tanko, Jason G. Gillmore, Robert Friedline, M'Hamed Chahma

Faculty Publications

Following a protocol developed by Mathivanan, Johnston, and Wayner (J. Phys. Chem. 1995, 99, 8190−8195), the radical anions of several cyclopropyl- and oxiranyl-containing carbonyl compounds were generated in an effort to measure the rate constants for their ring opening (ko) by laser flash photolysis. The results of these experiments are compared to those obtained from earlier electrochemical studies, and the combined data set is used to rationalize the kinetics of radical anion ring opening in a general context by using Savéant's theory pertaining to stepwise dissociative electron transfer (Acc. Chem. Res. 1993, 26, 455−461). Compared to cyclopropylcarbinyl → homoallyl rearrangements …

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Two-Neutron Transfer In The 6he + 209bi Reaction Near The Coulomb Barrier, Paul A. Deyoung, Patrick J. Mears, J. J. Kolata, E. F. Aguilera, F. D. Becchetti, Y. Chen, M. Cloughesy, H. Griffin, C. Guess, J. D. Hinnefeld, H. Jiang, Scott R. Jones, U. Khadka, D. Lizcano, E. Martinez-Quiroz, M. Ojaniega, Graham F. Peaslee, A. Pena, J. Reith, S. Vandendriessche, J. A. Zimmerman May 2005

Two-Neutron Transfer In The 6he + 209bi Reaction Near The Coulomb Barrier, Paul A. Deyoung, Patrick J. Mears, J. J. Kolata, E. F. Aguilera, F. D. Becchetti, Y. Chen, M. Cloughesy, H. Griffin, C. Guess, J. D. Hinnefeld, H. Jiang, Scott R. Jones, U. Khadka, D. Lizcano, E. Martinez-Quiroz, M. Ojaniega, Graham F. Peaslee, A. Pena, J. Reith, S. Vandendriessche, J. A. Zimmerman

Faculty Publications

The cross section for α-particle emission in the He6+Bi209 reaction at energies near the Coulomb barrier is remarkably large. Possible reactions that may produce the observed α particles include two-neutron transfer, one-neutron transfer, and direct projectile breakup. Each of these mechanisms results in a distinctive angular correlation between the α particle and the outgoing neutron(s). A neutron-α-particle coincidence experiment was performed to study two-neutron transfer to unbound states of Bi211. It is shown that approximately 55% of the observed α-particle yield at and beyond the grazing angle is because of this process. This is more than 2.5 times the fraction …

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Temperature-Dependent Asymmetry Of The Nonlocal Spin-Injection Resistance: Evidence For Spin Nonconserving Interface Scattering, Samir Garzon, Igor Žutić, Richard A. Webb May 2005

Temperature-Dependent Asymmetry Of The Nonlocal Spin-Injection Resistance: Evidence For Spin Nonconserving Interface Scattering, Samir Garzon, Igor Žutić, Richard A. Webb

Faculty Publications

We report nonlocal spin injection and detection experiments on mesoscopic Co-Al2O3-Cu spin valves. We have observed a temperature-dependent asymmetry in the nonlocal resistance between parallel and antiparallel configurations of the magnetic injector and detector. This strongly supports the existence of a nonequilibrium resistance that depends on the relative orientation of the detector magnetization and the nonequilibrium magnetization in the normal metal providing evidence for increasing interface spin scattering with temperature.

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