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Articles 2731 - 2760 of 3798

Full-Text Articles in Physical Sciences and Mathematics

Multisymplectic Theory Of Balance Systems, I, Serge Preston Feb 2008

Multisymplectic Theory Of Balance Systems, I, Serge Preston

Mathematics and Statistics Faculty Publications and Presentations

In this paper we are presenting the theory of balance equations of the Continuum Thermodynamics (balance systems) in a geometrical form using Poincare-Cartan formalism of the Multisymplectic Field Theory. A constitutive relation C of a balance system BC is realized as a mapping between a (partial) 1-jet bundle of the configurational bundle π : Y ͢ X and the extended dual bundle similar to the Legendre mapping of the Lagrangian Field Theory. Invariant (variational) form of the balance system BC is presented in three different forms and the space of admissible variations is defined and studied. Action of automorphisms …


Broadband Moth-Eye Antireflection Coatings On Silicon, Chih-Hung Sun, Peng Jiang, Bin Jiang Feb 2008

Broadband Moth-Eye Antireflection Coatings On Silicon, Chih-Hung Sun, Peng Jiang, Bin Jiang

Mathematics and Statistics Faculty Publications and Presentations

We report a bioinspired templating technique for fabricating broadband antireflection coatings that mimic antireflective moth eyes. Wafer-scale, subwavelength-structured nipple arrays are directly patterned on silicon using spin-coated silica colloidal monolayers as etching masks. The templated gratings exhibit excellent broadband antireflection properties and the normal-incidence specular reflection matches with the theoretical prediction using a rigorous coupled-wave analysis (RCWA) model. We further demonstrate that two common simulation methods, RCWA and thin-film multilayer models, generate almost identical prediction for the templated nipple arrays. This simple bottom-up technique is compatible with standard microfabrication, promising for reducing the manufacturing cost of crystalline silicon solar cells.


A Framework For Relationship Pattern Languages, Sudarshan Murthy, David Maier Feb 2008

A Framework For Relationship Pattern Languages, Sudarshan Murthy, David Maier

Computer Science Faculty Publications and Presentations

A relationship pattern is an abstraction of a recurring need when establishing relationships among information elements in specific contexts. By developing or leveraging a relationship pattern, modelers can solve a class of problems once and describe many relationship types at once. We have developed a framework for specifying relationship patterns and pattern languages (sets of patterns) in both modeling-language-independent and modeling-language-specific ways. We describe this framework both informally and formally. We provide examples of some commonly observed relationship patterns and show how to use them in ER with the help of a relationship pattern language called Exemplar. We also provide …


Temporal Variations In Physical And Chemical Features Of Cryoconite Holes On Canada Glacier, Mcmurdo Dry Valleys, Antarctica, Andrew G. Fountain, Thomas H. Nylen, Martyn Tranter, Elizabeth A. Bagshaw Jan 2008

Temporal Variations In Physical And Chemical Features Of Cryoconite Holes On Canada Glacier, Mcmurdo Dry Valleys, Antarctica, Andrew G. Fountain, Thomas H. Nylen, Martyn Tranter, Elizabeth A. Bagshaw

Geography Faculty Publications and Presentations

Cryoconite holes in the McMurdo Dry Valleys are ice-lidded, thus isolating the pools of water from the atmosphere and from potential surface melt. Hourly measurements of ice and water temperature and water electrical conductivity (EC) were recorded to broadly characterize the physical and chemical changes on daily to seasonal timescales. Overall, subsurface ice/water temperatures were typically several degrees warmer than air temperatures, underscoring the importance of subsurface solar heating. At no time was surface melt observed and the holes melted from within. Detailed differences in the timing and magnitude of both temperature and EC variations during melt-out and freezeup existed …


Modulation Of Water Exchange In Europium(Iii) Dota–Tetraamide Complexes Via Electronic Substituent Effects, S. James Ratnakar, Mark Woods, Angelo J.M. Lubag, Zoltan Kovacs, A. Dean Sherry Jan 2008

Modulation Of Water Exchange In Europium(Iii) Dota–Tetraamide Complexes Via Electronic Substituent Effects, S. James Ratnakar, Mark Woods, Angelo J.M. Lubag, Zoltan Kovacs, A. Dean Sherry

Chemistry Faculty Publications and Presentations

The chemical exchange saturation transfer (CEST) efficiency for a series Eu3+-based tetraamide complexes bearing p-substituents on a single coordinating pendant arm is highly sensitive to water exchange rates. The CEST effect increases in the order Me < MeO < F ∼ CO2tBu < CN ≪ H. These results show that CEST contrast can be modulated by changes in electron density at a single ligating atom, and this forms the basis of creating imaging agents that respond to chemical oxidation and reduction.


Inventory And Mapping Of Aquatic Plants At Lake Roosevelt National Recreation Area, Mark D. Sytsma, Rich Miller Jan 2008

Inventory And Mapping Of Aquatic Plants At Lake Roosevelt National Recreation Area, Mark D. Sytsma, Rich Miller

Center for Lakes and Reservoirs Publications and Presentations

Lake Roosevelt is a large reservoir in northeast Washington State formed by the Grand Coulee Dam. The reservoir, which inundates portions of the Columbia River, the Spokane River, and other rivers and streams, is the focus of the Lake Roosevelt National Recreation Area (LARO) that is managed by the National Park Service. LARO encompasses 100,390 acres (40,625 ha) and includes significant cultural and recreational resources. The surface area, volume, and shoreline length of Lake Roosevelt at full pool is 82,691 acres (33,490 ha), 9.41 × 1010 acre-ft (1.16 × 1010 m3) (Nigro et. al. 1981), and …


Constructive Perception Of Self-Motion, Jan E. Holly, Gin Mccollum Jan 2008

Constructive Perception Of Self-Motion, Jan E. Holly, Gin Mccollum

Gin McCollum

This review focusses attention on a ragged edge of our knowledge of self-motion perception, where understanding ends but there are experimental results to indicate that present approaches to analysis are inadequate. Although self-motion perception displays processes of “top-down” construction, it is typically analyzed as if it is nothing more than a deformation of the stimulus, using a “bottom-up” and input/output approach beginning with the transduction of the stimulus. Analysis often focusses on the extent to which passive transduction of the movement stimulus is accurate. Some perceptual processes that deform or transform the stimulus arise from the way known properties of …


The Ownership Of The Internet And The World Wide Web In Vermont, Ida Kubiszewski Jan 2008

The Ownership Of The Internet And The World Wide Web In Vermont, Ida Kubiszewski

Institute for Sustainable Solutions Publications and Presentations

The internet is an interesting case, since it was created entirely with taxpayer's money by DARPA, while the world wide web was created at CERN in Switzerland and placed into the public domain voluntarily in 1993. The internet and web have many features of a commons, and many people refer to the "internet commons". Kubiszewski (pronounced cube- ih-shefski) explores the intricacies of the internet and world wide web to determine if internet companies are extracting economic rent from the public and how it could be recovered. She finds that companies are making a substantial profit by utilizing a resource that …


Traffic Analysis Of Udp-Based Flows In Ourmon, Jim Binkley, Divya Parekh Jan 2008

Traffic Analysis Of Udp-Based Flows In Ourmon, Jim Binkley, Divya Parekh

Computer Science Faculty Publications and Presentations

We present a custom UDP flow tuple with an IP address key and a set of simple related statistical attributes. Attributes are used to calculate a per host metric called the UDP work weight which roughly measures the amount of network noise caused by a host. The work weight is used to produce a near real-time sorted top N report for UDP host tuples. We also present a derived attribute based on an algorithm called the UDP guesstimator. The UDP guesstimator roughly classifies port report hosts into various traffic categories including security threats (DOS/scanning) or P2P hosts based on high …


Controlled Fabrication Of High-Yield Cds Nanostructures By Compartment Arrangement, Joshua M. Green, Juno Lawrance, Jun Jiao Jan 2008

Controlled Fabrication Of High-Yield Cds Nanostructures By Compartment Arrangement, Joshua M. Green, Juno Lawrance, Jun Jiao

Physics Faculty Publications and Presentations

High-yield, high-purity CdS nanostructures were synthesized in a turf-like configuration using an improved vapor-liquid-solid method. To increase the yield, a compartment arrangement was employed. The specific kind of nanostructure fabricated was found to be directly dependent on the temperature in the compartment. Along with the high-yield growth of CdS nanorods, nanowires, and nanobelts, intertwined structures were also observed, and the electron field emission property of the intertwined structures was investigated and compared with that of other type of nanostructures. Photoluminescence measurements at 10 K showed a peak emission from the CdS nanostructures at 485 nm.


Rapid Assessment Of 2008-2012 Highway Development Projects In Region 6: Threats And Opportunities To Terrestrial Wildlife Resources, Sandra L. Jacobson, Catherine E. De Rivera, Kathleen Armstrong, Rebecca Aaby, Nadia Jones Jan 2008

Rapid Assessment Of 2008-2012 Highway Development Projects In Region 6: Threats And Opportunities To Terrestrial Wildlife Resources, Sandra L. Jacobson, Catherine E. De Rivera, Kathleen Armstrong, Rebecca Aaby, Nadia Jones

Environmental Science and Management Faculty Publications and Presentations

Summaries of Highway Development Projects in Region 6 National Forests.

This document contains a summary of higher complexity projects selected for their interest to line officers and resource managers. These projects represent not only the current Statewide Transportation Improvement Plan (STIP) projects but also a sample of the types of projects that will be on future STIPs. Thus, readers are urged to glance at the tracking tools and narratives for all forests to gain a quick glimpse of the types of projects potentially facing each forest. The summary has extracted brief information on project locations and types, the program year …


An Embarrassment Of Riches: The Enzymology Of Rna Modification, Dirk Iwata-Reuyl Jan 2008

An Embarrassment Of Riches: The Enzymology Of Rna Modification, Dirk Iwata-Reuyl

Chemistry Faculty Publications and Presentations

The maturation of transfer RNA (tRNA) involves extensive chemical modification of the constituent nucleosides and results in the introduction of significant chemical diversity to tRNA. Many of the pathways to these modified nucleosides are characterized by chemically complex transformations, some of which are unprecedented in other areas of biology. To illustrate the scope of the field, recent progress in understanding the enzymology leading to the formation of two distinct classes of modified nucleosides, the thiouridines and queuosine, a 7-deazaguanosine, is reviewed. In particular, recent data validating the involvement of several proposed intermediates in the formation of thiouridines are discussed, including …


Invasive Predator, Bythotrephes, Has Varied Effects On Ecosystem Function In Freshwater Lakes, Angela L. Strecker, Shelley E. Arnott Jan 2008

Invasive Predator, Bythotrephes, Has Varied Effects On Ecosystem Function In Freshwater Lakes, Angela L. Strecker, Shelley E. Arnott

Environmental Science and Management Faculty Publications and Presentations

Bythotrephes longimanus is an invertebrate predator that has invaded the North American Great Lakes and a number of inland lakes, where it preys on crustacean zooplankton. We examined the effect of Bythotrephes on two measures of ecosystem function during a four month observational study of freshwater lakes on the boreal shield. Bythotrephes-invaded lakes had significantly lower epilimnetic zooplankton abundance and production compared to reference lakes. On average, Bythotrephes consumed 34% ofzooplankton production when it was present in lakes. There was some evidence of changes in the timing of zooplankton production, as well as shifts to cooler, less productive habitats, which …


Differential Effects Of Understory And Overstory Gaps On Tree Regeneration, Brian Beckage, Brian D. Kloeppel, J. Alan Yeakley, Sharon F. Taylor, David C. Coleman Jan 2008

Differential Effects Of Understory And Overstory Gaps On Tree Regeneration, Brian Beckage, Brian D. Kloeppel, J. Alan Yeakley, Sharon F. Taylor, David C. Coleman

Environmental Science and Management Faculty Publications and Presentations

Gaps in the forest canopy can increase the diversity of tree regeneration. Understory shrubs also compete with tree seedlings for limited resources and may depress tree recruitment. We compared effects of shrub removal and canopy windthrow gaps on seedling recruitment and understory resource levels. Shrub removal, with the canopy left intact, was associated with increased levels of understory light and soil moisture and coincided with increased species richness and diversity of tree regeneration compared to both control plots and canopy gaps. Canopy windthrow gaps, however, resulted in a more than 500 fold increase in soil nitrate concentrations, and seedling growth …


Superior Adaptation To Drought In Rubus Armeniacus (Himalayan Blackberry) In Northwest Oregon, J. Alan Yeakley, Joshua S. Caplan Jan 2008

Superior Adaptation To Drought In Rubus Armeniacus (Himalayan Blackberry) In Northwest Oregon, J. Alan Yeakley, Joshua S. Caplan

Environmental Science and Management Faculty Publications and Presentations

Despite the status Rubus armeniacus (Himalayan blackberry) has as one of the most prolific and damaging plant invaders in the Pacific Northwest, we know little about the role of water relations in its success. The information available on invasive blackberry water relations (Fotelli et al. 2001; McDowell and Turner 2002) suggests that an ability to avoid water stress has been critically important to their proliferation in regions with Mediterranean climates (Amor et al. 1998). We had two objectives regarding the role of water relations in the invasive success of R. armeniacus:

Objective 1. Determine if R. armeniacus is better adapted …


Engaging Recreational Fishers In Management And Conservation: Global Case Studies, Elise F. Granek, Elizabeth M.P. Madin, M. A. Brown, Will F. Figueira, Darren S. Cameron, Zeb Hogan, Gerry Kristianson, Pierre De Villiers, Jack E. Williams, John R. Post, S. Zahn, R. Arlinghaus Jan 2008

Engaging Recreational Fishers In Management And Conservation: Global Case Studies, Elise F. Granek, Elizabeth M.P. Madin, M. A. Brown, Will F. Figueira, Darren S. Cameron, Zeb Hogan, Gerry Kristianson, Pierre De Villiers, Jack E. Williams, John R. Post, S. Zahn, R. Arlinghaus

Environmental Science and Management Faculty Publications and Presentations

Globally, the number of recreational fishers is sizeable and increasing in many countries. Associated with this trend is the potential for negative impacts on fish stocks through exploitation or management measures such as stocking and introduction of non-native fishes. Nevertheless, recreational fishers can be instrumental in successful fisheries conservation through active involvement in, or initiation of, conservation projects to reduce both direct and external stressors contributing to fishery declines. Understanding fishers’ concerns for sustained access to the resource and developing methods for their meaningful participation can have positive impacts on conservation efforts. We examined a suite of case studies that …


Nutrient Uptake By Intact And Disturbed Roots Of Loblolly Pine Seedlings, Melissa S. Lucash, Ruth D. Yanai, J. Devereux Joslin Jan 2008

Nutrient Uptake By Intact And Disturbed Roots Of Loblolly Pine Seedlings, Melissa S. Lucash, Ruth D. Yanai, J. Devereux Joslin

Environmental Science and Management Faculty Publications and Presentations

Most measurements of nutrient uptake use either hydroponic systems or soil-grown roots that have been disturbed by excavation. The first objective of this study was to test how root excavation affects nitrate uptake. Rates of NO3− uptake by mycorrhizal loblolly pine (Pinus taeda L.) seedlings were measured in intact sand-filled columns, hydroponics, and disturbed sand-filled columns. Total nitrate uptake in intact sand-filled columns was higher than in disturbed columns, indicating that disturbance lowers uptake. Transferring plants from the sand-filled columns to hydroponics had little effect on NO3− uptake beyond delaying uptake for an hour. The second objective of this study …


Uniform Materials And The Multiplicative Decomposition Of The Deformation Gradient In Finite Elasto-Plasticity, Vincenzo Ciancio, Marina Dolfin, Mauro Francaviglia, Serge Preston Jan 2008

Uniform Materials And The Multiplicative Decomposition Of The Deformation Gradient In Finite Elasto-Plasticity, Vincenzo Ciancio, Marina Dolfin, Mauro Francaviglia, Serge Preston

Mathematics and Statistics Faculty Publications and Presentations

In this work we analyze the relation between the multiplicative decomposition F = F e F p of the deformation gradient as a product of the elastic and plastic factors and the theory of uniform materials. We prove that postulating such a decomposition is equivalent to having a uniform material model with two configurations – total φ and the inelastic φ1. We introduce strain tensors characterizing different types of evolutions of the material and discuss the form of the internal energy and that of the dissipative potential. The evolution equations are obtained for the configurations (φ, φ1) and the material …


The Indefinite Metric Of R. Mrugala And The Geometry Of The Thermodynamical Phase Space, Serge Preston, James Vargo Jan 2008

The Indefinite Metric Of R. Mrugala And The Geometry Of The Thermodynamical Phase Space, Serge Preston, James Vargo

Mathematics and Statistics Faculty Publications and Presentations

We study an indefinite metric G which was introduced by R. Mrugala and is defined on the contact phase space (P, θ) of a homogeneous thermodynamical system. We describe the curvature properties and the isometry group of the metric G. We established an isomorphism of the space (P, θ, G) with the Heisenberg Lie group Hn, endowed with the right invariant contact structure and the right invariant indefinite metric. The lift of the metric G to the symplectization of contact space (P, θ) and its properties are studied. Finally we introduce the "hyperbolic projectivization" of the space …


Electrical Detection Of The Temperature Induced Melting Transition Of A Dna Hairpin Covalently Attached To Gold Interdigitated Microelectrodes, Greg P. Brewood, Yaswanth Rangineni, Daniel J. Fish, Ashwini Bhandiwad, David R. Evans, Raj Solanki, Albert S. Benight Jan 2008

Electrical Detection Of The Temperature Induced Melting Transition Of A Dna Hairpin Covalently Attached To Gold Interdigitated Microelectrodes, Greg P. Brewood, Yaswanth Rangineni, Daniel J. Fish, Ashwini Bhandiwad, David R. Evans, Raj Solanki, Albert S. Benight

Chemistry Faculty Publications and Presentations

The temperature induced melting transition of a self-complementary DNA strand covalently attached at the 5' end to the surface of a gold interdigitated microelectrode (GIME) was monitored in a novel, label-free, manner. The structural state of the hairpin was assessed by measuring four different electronic properties of the GIME (capacitance, impedance, dissipation factor and phase angle) as a function of temperature from 25 degrees C to 80 degrees C. Consistent changes in all four electronic properties of the GIME were observed over this temperature range, and attributed to the transition of the attached single-stranded DNA (ssDNA) from an intramolecular, folded …


Chiral Recognition Of Amino Acids By Use Of A Fluorescent Resorcinarene, Gerald I. Richard, Hadi M. Marwani, Shan Jiang, Sayo O. Fakayode, Mark Lowry, Robert M. Strongin, Isiah M. Warner Jan 2008

Chiral Recognition Of Amino Acids By Use Of A Fluorescent Resorcinarene, Gerald I. Richard, Hadi M. Marwani, Shan Jiang, Sayo O. Fakayode, Mark Lowry, Robert M. Strongin, Isiah M. Warner

Chemistry Faculty Publications and Presentations

The spectroscopic properties of a chiral boronic acid based resorcinarene macrocycle employed for chiral analysis were investigated. Specifically, the emission and excitation characteristics of tetraarylboronate resorcinarene macrocycle (TBRM) and its quantum yield were evaluated. The chiral selector TBRM was investigated as a chiral reagent for the enantiomeric discrimination of amino acids using steady-state fluorescence spectroscopy. Chiral recognition of amino acids in the presence of the macrocycle was based on diastereomeric complexes. Results demonstrated that TBRM had better chiral discrimination ability for lysine as compared to the other amino acids. Partial least squares regression modeling (PLS-1) of spectral data for macrocycle-lysine …


Synthesis And Characterization Of Novel Chiral Ionic Liquids And Investigation Of Their Enantiomeric Recognition Properties, David K. Bwambok, Hadi M. Marwani, Vivian E. Fernand, Sayo O. Fakayode, Mark Lowry, Ioan Negulescu, Robert M. Strongin, Isiah M. Warner Jan 2008

Synthesis And Characterization Of Novel Chiral Ionic Liquids And Investigation Of Their Enantiomeric Recognition Properties, David K. Bwambok, Hadi M. Marwani, Vivian E. Fernand, Sayo O. Fakayode, Mark Lowry, Ioan Negulescu, Robert M. Strongin, Isiah M. Warner

Chemistry Faculty Publications and Presentations

We report the synthesis and characterization of amino acid ester based chiral ionic liquids, derived from L- and D-alanine tert butyl ester chloride. The synthesis was accomplished via an anion metathesis reaction between commercially available L- and D-alanine tert butyl ester chloride using a variety of counterions such as lithium bis (trifluoromethane) sulfonimide, silver nitrate, silver lactate, and silver tetrafluoroborate. Both enantiomeric forms were obtained as confirmed by bands of opposite sign in the circular dichroism spectra. The L- and D-alanine tert butyl ester bis (trifluoromethane) sulfonimide were obtained as liquids at room temperature and intriguingly exhibited the highest thermal …


Unsymmetric Aryl–Alkyl Disulfide Growth Inhibitors Of Methicillin-Resistant Staphylococcus Aureus And Bacillus Anthracis, Edward Turos, Kevin D. Revell, Praveen Ramaraju, Danielle A. Gergeres, Kerriann Greenhalgh, Ashley Young, Nalini Sathyanarayan, Sonja Dickey, Daniel Lim, Mamoun M. Alhamadsheh, Kevin A. Reynolds Jan 2008

Unsymmetric Aryl–Alkyl Disulfide Growth Inhibitors Of Methicillin-Resistant Staphylococcus Aureus And Bacillus Anthracis, Edward Turos, Kevin D. Revell, Praveen Ramaraju, Danielle A. Gergeres, Kerriann Greenhalgh, Ashley Young, Nalini Sathyanarayan, Sonja Dickey, Daniel Lim, Mamoun M. Alhamadsheh, Kevin A. Reynolds

Chemistry Faculty Publications and Presentations

This study describes the antibacterial properties of synthetically-produced mixed aryl alkyl disulfide compounds as a means to control the growth of Staphylococcus aureus and Bacillus anthracis. Some of these compounds exerted strong in vitro bioactivity. Our results indicate that among the twelve different aryl substituents examined, nitrophenyl derivatives provide the strongest antibiotic activities. This may be the result of electronic activation of the arylthio moiety as a leaving group for nucleophilic attack on the disulfide bond. Small alkyl residues on the other sulfur provide the best activity as well, which for different bacteria appears to be somewhat dependent on …


The Cis-Δ2,3-Double Bond Of Phoslactomycins Is Generated By A Post-Pks Tailoring Enzyme, Nadaraj Palaniappan, Mamoun M. Alhamadsheh, Kevin A. Reynolds Jan 2008

The Cis-Δ2,3-Double Bond Of Phoslactomycins Is Generated By A Post-Pks Tailoring Enzyme, Nadaraj Palaniappan, Mamoun M. Alhamadsheh, Kevin A. Reynolds

Chemistry Faculty Publications and Presentations

The antifungal phoslactomycins (PLM A-F), produced by Streptomyes sp HK803, are structurally unusual in that three of their four double bonds are in the cis form (Δ12,13, Δ14,15, Δ2,3). The PLM polyketide synthase (PKS) has the predicted dehydratase catalytic domain in modules 1,2 and 5 required for establishing two of these cis double bonds (Δ12,13Δ14,15), as well as the only trans Δ6,7double bond. By contrast, the formation of the cis Δ2,3 in the unsaturated lactone moiety of PLMs has presented an enigma because the predicted dehydratase domain …


Glacial Ecosystems, Amy Hodson, Alexandre M. Anesio, Martyn Tranter, Andrew G. Fountain, Mark Osborn, John Charles Priscu, Johanna Laybourn-Perry, Birgit Sattler Jan 2008

Glacial Ecosystems, Amy Hodson, Alexandre M. Anesio, Martyn Tranter, Andrew G. Fountain, Mark Osborn, John Charles Priscu, Johanna Laybourn-Perry, Birgit Sattler

Geography Faculty Publications and Presentations

There is now compelling evidence that microbially mediated reactions impart a significant effect upon the dynamics, composition, and abundance of nutrients in glacial melt water. Consequently, we must now consider ice masses as ecosystem habitats in their own right and address their diversity, functional potential, and activity as part of alpine and polar environments. Although such research is already underway, its fragmentary nature provides little basis for developing modern concepts of glacier ecology. This paper therefore provides a much-needed framework for development by reviewing the physical, biogeochemical, and microbiological characteristics of microbial habitats that have been identified within glaciers and …


Correction To "Stochastic Comparisons Of Parallel Systems When Components Have Proportional Hazard Rates", Subhash C. Kochar, Maochao Xu Jan 2008

Correction To "Stochastic Comparisons Of Parallel Systems When Components Have Proportional Hazard Rates", Subhash C. Kochar, Maochao Xu

Mathematics and Statistics Faculty Publications and Presentations

In the article "Stochastic comparisons of parallel systems when component have proportional hazard rates" we found a gap in the middle of the proof of Theorem 3.2. Therefore, we do not know whether Theorem 3.2 is true for the reverse hazard rate order. However, we could prove the following weaker result for the stochastic order.


Polynomial Extension Operators. Part I, Leszek Demkowicz, Jay Gopalakrishnan, Joachim Schöberl Jan 2008

Polynomial Extension Operators. Part I, Leszek Demkowicz, Jay Gopalakrishnan, Joachim Schöberl

Mathematics and Statistics Faculty Publications and Presentations

In this series of papers, we construct operators that extend certain given functions on the boundary of a tetrahedron into the interior of the tetrahedron, with continuity properties in appropriate Sobolev norms. These extensions are novel in that they have certain polynomial preservation properties important in the analysis of high order finite elements. This part of the series is devoted to introducing our new technique for constructing the extensions, and its application to the case of polynomial extensions from H½(∂K) into H¹(K), for any tetrahedron K.


A Mixed Method For Axisymmetric Div-Curl Systems, Dylan M. Copeland, Jay Gopalakrishnan, Joseph E. Pasciak Jan 2008

A Mixed Method For Axisymmetric Div-Curl Systems, Dylan M. Copeland, Jay Gopalakrishnan, Joseph E. Pasciak

Mathematics and Statistics Faculty Publications and Presentations

We present a mixed method for a three-dimensional axisymmetric div-curl system reduced to a two-dimensional computational domain via cylindrical coordinates. We show that when the meridian axisymmetric Maxwell problem is approximated by a mixed method using the lowest order Nédélec elements (for the vector variable) and linear elements (for the Lagrange multiplier), one obtains optimal error estimates in certain weighted Sobolev norms. The main ingredient of the analysis is a sequence of projectors in the weighted norms satisfying some commutativity properties.


Order Restricted Inference For Comparing The Cumulative Incidence Of A Competing Risk Over Several Populations, Hammou El Barmi, Subhash C. Kochar, Hari Mukerjee Jan 2008

Order Restricted Inference For Comparing The Cumulative Incidence Of A Competing Risk Over Several Populations, Hammou El Barmi, Subhash C. Kochar, Hari Mukerjee

Mathematics and Statistics Faculty Publications and Presentations

There is a substantial literature on testing for the equality of the cumulative incidence functions associated with one specific cause in a competing risks setting across several populations against specific or all alternatives. In this paper we propose an asymptotically distribution-free test when the alternative is that the incidence functions are linearly ordered, but not equal. The motivation stems from the fact that in many examples such a linear ordering seems reasonable intuitively and is borne out generally from empirical observations. These tests are more powerful when the ordering is justified. We also provide estimators of the incidence functions under …


Multigrid Convergence For Second Order Elliptic Problems With Smooth Complex Coefficients, Jay Gopalakrishnan, Joseph E. Pasciak Jan 2008

Multigrid Convergence For Second Order Elliptic Problems With Smooth Complex Coefficients, Jay Gopalakrishnan, Joseph E. Pasciak

Mathematics and Statistics Faculty Publications and Presentations

The finite element method when applied to a second order partial differential equation in divergence form can generate operators that are neither Hermitian nor definite when the coefficient function is complex valued. For such problems, under a uniqueness assumption, we prove the continuous dependence of the exact solution and its finite element approximations on data provided that the coefficients are smooth and uniformly bounded away from zero. Then we show that a multigrid algorithm converges once the coarse mesh size is smaller than some fixed number, providing an efficient solver for computing discrete approximations. Numerical experiments, while confirming the theory, …