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A Study Of Enso Prediction Using A Hybrid Coupled Model And The Adjoint Method For Data Assimilation, Eli Galanti, Eli Tziperman, Matthew Harrison, Anthony Rosati, Ziv Sirkes Nov 2003

A Study Of Enso Prediction Using A Hybrid Coupled Model And The Adjoint Method For Data Assimilation, Eli Galanti, Eli Tziperman, Matthew Harrison, Anthony Rosati, Ziv Sirkes

Faculty Publications

An experimental ENSO prediction system is presented, based on an ocean general circulation model (GCM) coupled to a statistical atmosphere and the adjoint method of 4D variational data assimilation. The adjoint method is used to initialize the coupled model, and predictions are performed for the period 1980-99. The coupled model is also initialized using two simpler assimilation techniques: forcing the ocean model with observed sea surface temperature and surface fluxes, and a 3D variational data assimilation (3DVAR) method, similar to that used by the National Centers for Environmental Prediction (NCEP) for operational ENSO prediction. The prediction skill of the coupled …

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Heralded Two-Photon Entanglement From Probabilistic Quantum Logic Operations On Multiple Parametric Down-Conversion Sources, Todd B. Pittman, Michelle M. Donegan, Michael J. Fitch, Bryan C. Jacobs, James D. Franson, Pieter Kok, Hwang Lee, Jonathan P. Dowling Nov 2003

Heralded Two-Photon Entanglement From Probabilistic Quantum Logic Operations On Multiple Parametric Down-Conversion Sources, Todd B. Pittman, Michelle M. Donegan, Michael J. Fitch, Bryan C. Jacobs, James D. Franson, Pieter Kok, Hwang Lee, Jonathan P. Dowling

Faculty Publications

An ideal controlled-NOT gate followed by projective measurements can be used to identify specific Bell states of its two input qubits. When the input qubits are each members of independent Bell states, these projective measurements can be used to swap the post-selected entanglement onto the remaining two qubits. Here we apply this strategy to produce heralded two-photon polarization entanglement using Bell states that originate from independent parametric down-conversion sources, and a particular probabilistic controlled-NOT gate that is constructed from linear optical elements. The resulting implementation is closely related to an earlier proposal by Sliwa and Banaszek, and can be intuitively …

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On The Minor-Minimal 3-Connected Matroids Having A Fixed Minor, Manoel Lemos, James Oxley Nov 2003

On The Minor-Minimal 3-Connected Matroids Having A Fixed Minor, Manoel Lemos, James Oxley

Faculty Publications

Let N be a minor of a 3-connected matroid M such that no proper 3-connected minor of M has N as a minor. This paper proves a bound on E(M)-E(N) that is sharp when N is connected. © 2003 Elsevier Ltd. All rights reserved.

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Rules And Fuzzy Rules In Text: Concept, Extraction And Usage, D. H. Kraft, M. J. Martín-Bautista, J. Chen, D. Sánchez Nov 2003

Rules And Fuzzy Rules In Text: Concept, Extraction And Usage, D. H. Kraft, M. J. Martín-Bautista, J. Chen, D. Sánchez

Faculty Publications

Several concepts and techniques have been imported from other disciplines such as Machine Learning and Artificial Intelligence to the field of textual data. In this paper, we focus on the concept of rule and the management of uncertainty in text applications. The different structures considered for the construction of the rules, the extraction of the knowledge base and the applications and usage of these rules are detailed. We include a review of the most relevant works of the different types of rules based on their representation and their application to most of the common tasks of Information Retrieval such as …

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An Improved Simulation Model For Spaceborne Scatterometer Measurements, David G. Long, Peter K. Yoho Nov 2003

An Improved Simulation Model For Spaceborne Scatterometer Measurements, David G. Long, Peter K. Yoho

Faculty Publications

Development of scatterometer designs and applications requires extensive data simulation. The advancing capabilities of instruments motivates our proposal for an improved simulation model for noisy scatterometer measurements. Previous simulation models do not separately account for the two forms of random variation - signal fading and additive noise - which affect scatterometer measurements. The proposed model is able to generate data that are statistically equivalent (in a mean and variance sense) to actual instrument measurements by accounting for both variations, while maintaining ease of implementation. The model is particularly adept at handling design tradeoffs related to signal-to-noise ratios by appropriately separating …

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Jet Production In Charged Current Deep Inelastic E+P Scattering 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 Nov 2003

Jet Production In Charged Current Deep Inelastic E+P Scattering 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

The production rates and substructure of jets have been studied in charged current deep inelastic e+p scattering for Q2 > 200 GeV2 with the ZEUS detector at HERA using an integrated luminosity of 110.5 pb-1. Inclusive jet cross sections are presented for jets with transverse energies ETjet > 14 GeV and pseudorapidities in the range -1 < ηjet < 2. Dijet cross sections are presented for events with a jet having ETjet > 14 GeV and a second jet having ETjet > 5 GeV. Measurements of the mean subjet multiplicity, 〈ηsbj〉, of the inclusive jet sample are presented. Predictions based on parton-shower Monte Carlo models and next-to-leading-order QCD calculations are compared to the measurements. The value of αs (MZ), determined …

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Measurement Of Deeply Virtual Compton Scattering 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 Oct 2003

Measurement Of Deeply Virtual Compton Scattering 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

The cross-section for deeply virtual Compton scattering in the reaction ep → eγp has been measured with the ZEUS detector at HERA using integrated luminosities of 95.0 pb-1 of e+p and 16.7 pb-1 of e-p collisions. Differential cross-sections are presented as a function of the exchanged-photon virtuality, Q2, and the centre-of-mass energy, W, of the γ*p system in the region 5 < Q2 < 100 GeV2 and 40 < W < 140 GeV. The measured cross-sections rise steeply with increasing W. The measurements are compared to QCD-based calculations. © 2003 Elsevier B.V. All rights reserved.

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Ordering Tendencies In Octahedral Mgo-Zno Alloys, Gus L. W. Hart, Mahdi Sanati, Alex Zunger Oct 2003

Ordering Tendencies In Octahedral Mgo-Zno Alloys, Gus L. W. Hart, Mahdi Sanati, Alex Zunger

Faculty Publications

Isostrutural II-VI alloys whose components are either rocksalt stable (e.g., CaO-MgO) or zincblende stable (e.g., ZnS-ZnSe) are known to be thermodynamically unstable at low temperatures, showing a miscibility gap and no bulk ordering. In contrast, we show that heterostructural MgO-ZnO is stable, under certain conditions, in the sixfold-coordinated structure for Zn concentrations below 67%, giving rise to spontaneously ordered alloys. Using first-principles calculations, we explain the origin of this stability, the structures of their low-temperature ordered phases, short-range-order patterns, and their optical band-gap properties.

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Pyridoxamine Traps Intermediates In Lipid Peroxidation Reactions In Vivo: Evidence On The Role Of Lipids In Chemical Modification Of Protein And Development Of Diabetic Complications, Thomas O. Metz, Nathan L. Alderson, Mark E. Chachich, Suzanne R. Thorpe, John W. Baynes Oct 2003

Pyridoxamine Traps Intermediates In Lipid Peroxidation Reactions In Vivo: Evidence On The Role Of Lipids In Chemical Modification Of Protein And Development Of Diabetic Complications, Thomas O. Metz, Nathan L. Alderson, Mark E. Chachich, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

Maillard or browning reactions between reducing sugars and protein lead to formation of advanced glycation end products (AGEs) and are thought to contribute to the pathogenesis of diabetic complications. AGE inhibitors such as aminoguanidine and pyridoxamine (PM) inhibit both the formation of AGEs and development of complications in animal models of diabetes. PM also inhibits the chemical modification of protein by advanced lipoxidation end products (ALEs) during lipid peroxidation reactions in vitro. We show here that several PM adducts, formed in incubations of PM with linoleate and arachidonate in vitro, are also excreted in the urine of PM-treated animals. The …

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Mapping The Intellectual Structure Of Information Science And Information Technology: A Study Of Geographic Information Science, Anita Coleman Oct 2003

Mapping The Intellectual Structure Of Information Science And Information Technology: A Study Of Geographic Information Science, Anita Coleman

Faculty Publications

No abstract provided.

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Laplace And Segal-Bargmann Transforms On Hermitian Symmetric Spaces And Orthogonal Polynomials, Mark Davidson, Gestur Ólafsson, Genkai Zhang Oct 2003

Laplace And Segal-Bargmann Transforms On Hermitian Symmetric Spaces And Orthogonal Polynomials, Mark Davidson, Gestur Ólafsson, Genkai Zhang

Faculty Publications

Let D = G/K be a complex bounded symmetric domain of tube type in a complex Jordan algebra V and let Dℝ = J ∩ D ⊂ D be its real form in a formally real Euclidean Jordan algebra J ⊂ V; Dℝ = H/L is a bounded realization of the symmetric cone in J. We consider representations of H that are gotten by the generalized Segal-Bargmann transform from a unitary G-space of holomorphic functions on D to an L2-space on DR. We prove that in the unbounded realization the inverse of the unitary part of the restriction map is …

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Allowed Mesoscopic Point Group Symmetries In Domain Average Engineering Of Perovskite Ferroelectric Crystals, Dorian M. Hatch, H. T. Stokes, W. Cao Oct 2003

Allowed Mesoscopic Point Group Symmetries In Domain Average Engineering Of Perovskite Ferroelectric Crystals, Dorian M. Hatch, H. T. Stokes, W. Cao

Faculty Publications

In multivariant systems, several energetically degenerate low temperature domain states can be produced at the structural phase transition. Coexistence of these domain states can produce mesoscopic structures that possess symmetries distinct from the microscopic single domain crystal symmetry. Such engineered domain structures in certain ferroelectric materials have been proven to give superior piezoelectric properties and extremely soft shear moduli. The objective of this article is to consider the variety of symmetries that can be produced through domain average engineering in proper ferroelectric systems arising from the cubic Pm[overline 3]m symmetry perovskite structure.

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Solar Neutrinos, Sno And Neutrino-Deuteron Reactions, Vladimir Gudkov, Kuniharu Kubodera Oct 2003

Solar Neutrinos, Sno And Neutrino-Deuteron Reactions, Vladimir Gudkov, Kuniharu Kubodera

Faculty Publications

The standard nuclear physics approach and effective field theory approach for calculations of neutrino–deuteron cross sections for the solar neutrino energies are considered. Their main features, the level of accuracy and problems to be addressed for further developments are discussed.

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Predictive Joint Motion Limiting In Robotic Applications, Edward Red, Brian Fielding Oct 2003

Predictive Joint Motion Limiting In Robotic Applications, Edward Red, Brian Fielding

Faculty Publications

Three joint space algorithms slow the Cartesian path motion when it appears that joint motion is approaching a joint, speed, or acceleration limit. All three algorithms use quadratic curve fitting to predict where the joint motion is heading, followed by a prediction as to how much time would elapse until a limit is reached.

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Runoff And Sediment Losses From Annual And Unusual Storm Events From The Alto Experimental Watersheds, Texas: 23 Years After Silvicultural Treatments, Matthew W. Mcbroom, R Scott Beasley, Mingteh Chang, Brian Gowin, George G. Ice Oct 2003

Runoff And Sediment Losses From Annual And Unusual Storm Events From The Alto Experimental Watersheds, Texas: 23 Years After Silvicultural Treatments, Matthew W. Mcbroom, R Scott Beasley, Mingteh Chang, Brian Gowin, George G. Ice

Faculty Publications

Evaluating the potential impacts of intensive silvicultural practices on water quality is critical for establishing the long-term sustainability of contemporary forest management practices. From 1979 to 1985, a study involving nine small (~2.5 ha) forested watersheds was conducted near Alto, Texas in the upper western Gulf-Coastal Plain to evaluate the impacts then-current silvicultural practices on water quality. In the years following the study, silvicultural Best Management Practices (BMPs) including Streamside Management Zones (SMZs) and other erosion control practices evolved and questions arose about the applicability of earlier results to current practices. In 1999, these same watersheds were reinstrumented to evaluate …

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Nitric Oxide Mediates Seasonal Muscle Potentiation In Clam Gills, Louis F. Gainey Jr., Michael J. Greenberg Oct 2003

Nitric Oxide Mediates Seasonal Muscle Potentiation In Clam Gills, Louis F. Gainey Jr., Michael J. Greenberg

Faculty Publications

The physiology and timing of gill muscle potentiation were explored in the clam Mercenaria mercenaria. When isolated demibranchs were exposed twice (with an intervening wash) to the same concentration of 5-hydroxytryptamine, the second contraction was larger than the first. This potentiation was seasonal: it was present from November through June, and absent from July through October. Potentiation was not affected by the geographic origin of the clams, nor by their acclimation temperature. Potentiation was inhibited by the nitric oxide synthase (NOS) inhibitor L-NAME and mimicked by the nitric oxide (NO) donor DEANO. During the season of potentiation, immunoreactive NOS appeared …

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Action Based Approach To The Dynamics Of Extended Bodies In General Relativity, Jeeva Anandan, Naresh Dadhich, Parampreet Singh Oct 2003

Action Based Approach To The Dynamics Of Extended Bodies In General Relativity, Jeeva Anandan, Naresh Dadhich, Parampreet Singh

Faculty Publications

We present, for the first time, an action principle that gives the equations of motion of an extended body possessing multipole moments in an external gravitational field, in the weak field limit. From the action, the experimentally observable quantum phase shifts in the wavefunction of an extended object due to the coupling of its multipole moments with the gravitational field are obtained. Also, since the theory may be quantized using the action, the present approach is useful in the interface between general relativity and quantum mechanics.

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The Effect Of Density-Dependent Catastrophes On Population Persistence Time, Chris Wilcox, Bret Elderd Oct 2003

The Effect Of Density-Dependent Catastrophes On Population Persistence Time, Chris Wilcox, Bret Elderd

Faculty Publications

1. There has been increasing recognition that catastrophes are an important factor in modelling threatened populations. However, density dependence has generally been omitted from models of threatened populations on the assumption that this omission yields conservative predictions. We explore the significance of including density-dependent catastrophes in models of threatened populations. 2. Using an analytical model, we show that density-dependent catastrophes have a significant effect on population persistence, decreasing mean persistence time at large population sizes and causing a relative increase at intermediate sizes. 3. We illustrate our results with empirical data from a disease outbreak in crabeater seals Lobodon carcinophagus …

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On Series-Parallel Extensions Of Uniform Matroids, Brahim Chaourar, James Oxley Oct 2003

On Series-Parallel Extensions Of Uniform Matroids, Brahim Chaourar, James Oxley

Faculty Publications

This paper gives an excluded-minor characterization of the class of matroids that are series-parallel extensions of uniform matroids. © 2003 Elsevier Ltd. All rights reserved.

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The Nonexistence Of Regularization Operators, Ricardo Estrada Oct 2003

The Nonexistence Of Regularization Operators, Ricardo Estrada

Faculty Publications

We show that there are no continuous regularization procedures for the extension of distributions. We also show that there are no continuous projection operators from the spaces of distributions onto subspaces of distributions with support on a given closed set. © 2003 Elsevier Inc. All rights reserved.

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A Texture Evolution Model In Cubic-Orthotropic Polycrystalline System, Brent L. Adams, H. Garmestani, D. S. Li Sep 2003

A Texture Evolution Model In Cubic-Orthotropic Polycrystalline System, Brent L. Adams, H. Garmestani, D. S. Li

Faculty Publications

This work has been funded under the AFOSR Grant # F49620-03-1-0011 and Army Research Lab Contract # DAAD17-02-P-0398 and DAAD 19-01-1-0742. B.L. Adams acknowledges support of Army Research Office, Proposal No. 42566-MS. The authors express their sincere gratitude to Professor Surya Kalidindi, for helpful suggestions and correspondence for the derivation of the processing path functions. A new methodology based on a conservation principle in the orientation space is developed to simulate the texture evolution in a cubic-orthotropic polycrystalline system. A least squares error method was used to improve the accuracy of the simulation results obtained from the texture evolution function. …

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Quantum Noise In Gravitational-Wave Interferometers: Overview And Recent Developments, Thomas Corbitt, Nergis Mavalvala Sep 2003

Quantum Noise In Gravitational-Wave Interferometers: Overview And Recent Developments, Thomas Corbitt, Nergis Mavalvala

Faculty Publications

We present an overview of quantum noise in gravitational wave interferometers. Gravitational wave detectors are extensively modified variants of a Michelson interferometer and the quantum noise couplings are strongly influenced by the interferometer configuration. We describe recent developments in the treatment of quantum noise in the complex interferometer configurations of present-day and future gravitational-wave detectors. In addition, we explore prospects for the use of squeezed light in future interferometers, including consideration of the effects of losses, and the choice of optimal readout schemes.

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Search For ΝΜ→ΝE Oscillations In The Nomad Experiment, Nomad Collaboration, P. Astier, D. Autiero, A. Baldisseri, M. Baldo-Ceolin, M. Banner, G. Bassompierre, K. Benslama, N. Besson, I. Bird, B. Blumenfeld, F. Bobisut, J. Bouchez, S. Boyd, A. Bueno, S. Buyatov, L. Camilleri, A. Cardini, P. W. Cattaneo, V. Cavasinni, Roberto Petti, Et. Al. Sep 2003

Search For ΝΜ→ΝE Oscillations In The Nomad Experiment, Nomad Collaboration, P. Astier, D. Autiero, A. Baldisseri, M. Baldo-Ceolin, M. Banner, G. Bassompierre, K. Benslama, N. Besson, I. Bird, B. Blumenfeld, F. Bobisut, J. Bouchez, S. Boyd, A. Bueno, S. Buyatov, L. Camilleri, A. Cardini, P. W. Cattaneo, V. Cavasinni, Roberto Petti, Et. Al.

Faculty Publications

We present the results of a search for νµ → νe oscillations in the NOMAD experiment at CERN. The experiment looked for the appearance of νe in a predominantly νµ wide-band neutrino beam at the CERN SPS. No evidence for oscillations was found. The 90% confidence limits obtained are ∆m2 < 0.4 eV2 for maximal mixing and sin2(2θ)−3 for large ∆m2. This result excludes the LSND allowed region of oscillation parameters with ∆m2 ≳∆10 eV2.

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Trust Negotiation For Authentication And Authorization In Healthcare Information Systems, Charles D. Knutson, Kent E. Seamons, Tore L. Sundelin, David K. Vawdrey Sep 2003

Trust Negotiation For Authentication And Authorization In Healthcare Information Systems, Charles D. Knutson, Kent E. Seamons, Tore L. Sundelin, David K. Vawdrey

Faculty Publications

The expanding availability of health information in an electronic format is strategic for industry-wide efforts to improve the quality and reduce the cnst of health care. The implementation of electronic medical record systems has been hindered by inadequate security provisions. This paper describes the use of frust negotiation as a framework for providing authentication and access control services in healthcare information systems. nust negotiation enables two parties with no pre-existing relationship to establish the trust necessary to perform sensitive transactions via the mutual disclosure of attributes contained within digital credentials. An extension of this system, surrogate irusf negoikiion is introduced …

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The Cayley-Hamilton And Frobenius Theorems Via The Laplace Transform, William A. Adkins, Mark G. Davidson Sep 2003

The Cayley-Hamilton And Frobenius Theorems Via The Laplace Transform, William A. Adkins, Mark G. Davidson

Faculty Publications

The Cayley-Hamilton theorem on the characteristic polynomial of a matrix A and Frobenius' theorem on minimal polynomial of A are deduced from the familiar Laplace transform formula ℒ(e ) = (sI - A) . This formula is extended to a formal power series ring over an algebraically closed field of characteristic 0, so that the argument applies in the more general setting of matrices over a field of characteristic 0. © 2003 Elsevier Science Inc. All rights reserved. At -1

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A Stochastic Sediment Delivery Model For A Steep Mediterranean Landscape, Emmanuel Gabet, Thomas Dunne Sep 2003

A Stochastic Sediment Delivery Model For A Steep Mediterranean Landscape, Emmanuel Gabet, Thomas Dunne

Faculty Publications

It is a truism in geomorphology that climatic events operate on a landscape to drive sediment transport processes, yet few investigations have formally linked climate and terrain characteristics with geomorphological processes. In this study, we incorporate sediment transport equations derived from fieldwork into a computer model that predicts the delivery of sediment from hillslopes in a steep Mediterranean landscape near Santa Barbara, California. The sediment transport equations are driven by rainstorms and fires that are stochastically generated from probability distributions. The model is used to compare the rates and processes of sediment delivery under two vegetation types: coastal sage scrub …

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Scientific Collaboratories In Higher Education: Exploring Learning Style Preferences And Perceptions Of Technology, Diane H. Sonnenwald, Bin Li Sep 2003

Scientific Collaboratories In Higher Education: Exploring Learning Style Preferences And Perceptions Of Technology, Diane H. Sonnenwald, Bin Li

Faculty Publications

Scientific collaboratories hold the promise of providing students access to specialized scientific instruments, data and experts, enabling learning opportunities perhaps otherwise not available. However, evaluation of scientific collaboratories in higher education has lagged behind their development. We conducted a repeated-measures study that provided data regarding social interaction learning styles and perceptions of a scientific collaboratory system from 40 university science students working face-to-face and remotely. Students with a strong competitive learning style preference or who worked with a student with a strong competitive learning style reported a slightly more positive perception of the relative advantage, compatibility and complexity of the …

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Well Posed Constraint-Preserving Boundary Conditions For The Linearized Einstein Equations, Gioel Calabrese, Jorge Pullin, Oscar Reula, Olivier Sarbach, Manuel Tiglio Sep 2003

Well Posed Constraint-Preserving Boundary Conditions For The Linearized Einstein Equations, Gioel Calabrese, Jorge Pullin, Oscar Reula, Olivier Sarbach, Manuel Tiglio

Faculty Publications

In this paper we address the problem of specifying boundary conditions for Einstein's equations when linearized around Minkowski space using the generalized Einstein-Christoffel symmetric hyperbolic system of evolution equations. The boundary conditions we work out guarantee that the constraints are satisfied provided they are satisfied on the initial slice and ensures a well posed initial-boundary value formulation. We consider the case of a manifold with a non-smooth boundary, as is the usual case of the cubic boxes commonly used in numerical relativity. The techniques discussed should be applicable to more general cases, as linearizations around more complicated backgrounds, and may …

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Interactive Level-Set Smoothing For Photo Editing, Thomas C. Howard, Bryan S. Morse Sep 2003

Interactive Level-Set Smoothing For Photo Editing, Thomas C. Howard, Bryan S. Morse

Faculty Publications

This paper presents an interactive image-smoothing tool based on properties and manipulation of image level sets. This tool uses PDE-based level-set smoothing to preserve edge sharpness while smoothing noise and jagged contours. Unlike existing approaches using PDEs, the duration and areas of application are controlled interactively with immediate feedback to the user. Interaction issues are addressed, and parameters for adjusting the PDE are automatically estimated based on image characteristics.

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Target Sets: A Tool For Understanding And Predicting The Behavior Of Interacting Q-Learners, Nancy Fulda, Dan A. Ventura Sep 2003

Target Sets: A Tool For Understanding And Predicting The Behavior Of Interacting Q-Learners, Nancy Fulda, Dan A. Ventura

Faculty Publications

Reinforcement learning agents that interact in a common environment frequently affect each others’ perceived transition and reward distributions. This can result in convergence of the agents to a sub-optimal equilibrium or even to a solution that is not an equilibrium at all. Several modifications to the Q-learning algorithm have been proposed which enable agents to converge to optimal equilibria under specified conditions. This paper presents the concept of target sets as an aid to understanding why these modifications have been successful and as a tool to assist in the development of new modifications which are applicable in a wider range …

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