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Search Results: 1 - 10 of 480528 matches for " William A. Lester Jr "
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Quantum Monte Carlo methods for the solution of the Schroedinger equation for molecular systems
Alán Aspuru-Guzik,William A. Lester Jr
Physics , 2002,
Abstract: This is a book chapter soon to appear (2002) in the "Handbook for Numerical Analysis" volume dedicated to "Computational Chemistry" edited by Claude Le Bris. The series editors are P.G. Ciarlet and J. L. Lions. [North Holland/Elservier]. This review deals with some of the methods known under the umbrella term quantum Monte Carlo (QMC), specifically those that have been most commonly used for electronic structure.
Toribia del Val y el misterioso caminante de Casas de Benítez
Christian Jr., William A.
Revista de Dialectología y Tradiciones Populares , 2011, DOI: 10.3989/rdtp.2011.10
Abstract: The vision of a woman in her garden during a drought in a village in the Spanish province of Cuenca in 1931 suggests the vitality of old stories and the survival at the eve of the Spanish Civil War of the idea of a mysterious stranger or pilgrim, an old way of introducing heaven’s solutions to group problems. La visión experimentada en 1931 por una mujer en su huerto de un pueblo de Cuenca durante una sequía demuestra la pervivencia, en vísperas de la Guerra Civil espa ola, de la idea de un forastero o peregrino misterioso que aparece con instrucciones para el pueblo, una antigua manera de proponer soluciones celestiales a problemas colectivos.
Salt ingestion caves.
Lundquist Charles A.,Varnedoe Jr. William W.
International Journal of Speleology , 2006,
Abstract: Large vertebrate herbivores, when they find a salt-bearing layer of rock, say in a cliff face, can produce sizable voids where, overgenerations, they have removed and consumed salty rock. The cavities formed by this natural animal process constitute a uniqueclass of caves that can be called salt ingestion caves. Several examples of such caves are described in various publications. Anexample in Mississippi U.S.A., Rock House Cave, was visited by the authors in 2000. It seems to have been formed by deer orbison. Perhaps the most spectacular example is Kitum Cave in Kenya. This cave has been excavated to a length over 100 metersby elephants. An ancient example is La Cueva del Milodon in Chile, which is reported to have been excavated by the now extinctmilodon, a giant ground sloth. Still other possible examples can be cited. This class of caves deserves a careful definition. First, thecavity in rock should meet the size and other conventions of the locally accepted definition of a cave. Of course this requirement differsin detail from country to country, particularly in the matter of size. The intent is to respect the local conventions. The characteristicthat human entry is possible is judged to be a crucial property of any recognized cave definition. Second, the cavity should besignificantly the result of vertebrate animal consumption of salt-bearing rock. The defining process is that rock removed to form thecave is carried away in the digestive track of an animal. While sodium salts are expected to be the norm, other salts for which thereis animal hunger are acceptable. Also some other speleogenesis process, such as solution, should not be excluded as long as it issecondary in formation of a cave in question.
Ergot Alkaloid Effects on Bovine Sperm Motility In Vitro  [PDF]
Ryan Page, Toby Lester, Rick Rorie, Charles Rosenkrans Jr.
Advances in Reproductive Sciences (ARSci) , 2019, DOI: 10.4236/arsci.2019.71002
Abstract: Cattle in some parts of the world graze pastures that consist of tall fescue that may contain ergot alkaloid contamination. Those ergot alkaloids are associated with reduced reproductive rates in cattle. Our objective was to determine if ergot alkaloids [dihydroergotamine (DHET), ergonovine (EN), and ergotamine (ET)] directly affect bovine sperm characteristics. Spermatozoa were collected from mature Angus (n = 2) and Balancer (n = 4) bulls. Within bull, treatments were structured as a 3 × 5 factorial with three alkaloids (DHET, EN, and ET) and five concentrations of each alkaloid (0, 33, 66, 100, or 200 μM). Spermatozoa (25 × 106) were incubated (39?C) in 1 mL of modified sperm medium. Sperm motility characteristics were evaluated using CASA (Hamiliton Thorne IVOS, Beverly, MA) at 0, 3, and 6 h after initial alkaloid exposure. Initial sperm motility was (69% ± 1.1%) and declined (P = 0.01) to (35% ± 2.6%) at 6 h. Sperm motility decreased (P < 0.05) with increasing concentrations of DHET and ET, but not EN. As concentration of ET or DHET increased all CASA sperm characteristics were altered. The interaction of alkaloid concentration and incubation length affected sperm velocity and head size; exposure to 200 μM of ET or DHET for six hours decreased (P < 0.05) both characteristics. Our results demonstrate that ergot alkaloids (ET and DHET) can directly alter bovine sperm motility and morphology, which adds to our understanding of how ergot alkaloids may hinder cattle reproductive rates.
Host Immune Response to Intestinal Amebiasis
Shannon N. Moonah,Nona M. Jiang,William A. Petri Jr
PLOS Pathogens , 2013, DOI: 10.1371/journal.ppat.1003489
Abstract:
Josephson Junctions with a synthetic antiferromagnetic interlayer
Mazin A. Khasawneh,William P. Pratt, Jr.,Norman O. Birge
Physics , 2009, DOI: 10.1103/PhysRevB.80.020506
Abstract: We report measurements of the critical current vs. Co thickness in Nb/Cu/Co/Ru/Co/Cu/Nb Josephson junctions, where the inner Co/Ru/Co trilayer is a "synthetic antiferromagnet" with the magnetizations of the two Co layers coupled antiparallel to each other via the 0.6 nm-thick Ru layer. Due to the antiparallel magnetization alignment, the net intrinsic magnetic flux in the junction is nearly zero, and such junctions exhibit excellent Fraunhofer patterns in the critical current vs. applied magnetic field, even with total Co thicknesses as large as 23 nm. There are no apparent oscillations in the critical current vs. Co thickness, consistent with theoretical expectations for this situation. The critical current of the junctions decays over 4 orders of magnitude as the total Co thickness increases from 3 to 23 nm. These junctions may serve as useful templates for future explorations of spin-triplet superconducting correlations, which are predicted to occur in supercon- ducting/ferromagnetic hybrid systems in the presence of certain types of magnetic inhomogeneity.
An Efficient Radiative Cooling Approximation for Use in Hydrodynamic Simulations
James C. Lombardi Jr.,William G. McInally,Joshua A. Faber
Physics , 2014, DOI: 10.1093/mnras/stu2432
Abstract: To make relevant predictions about observable emission, hydrodynamical simulation codes must employ schemes that account for radiative losses, but the large dimensionality of accurate radiative transfer schemes is often prohibitive. Stamatellos and collaborators introduced a scheme for smoothed particle hydrodynamics (SPH) simulations based on the notion of polytropic pseudo-clouds that uses only local quantities to estimate cooling rates. The computational approach is extremely efficient and works well in cases close to spherical symmetry, such as in star formation problems. Unfortunately, the method, which takes the local gravitational potential as an input, can be inaccurate when applied to non-spherical configurations, limiting its usefulness when studying disks or stellar collisions, among other situations of interest. Here, we introduce the "pressure scale height method," which incorporates the fluid pressure scale height into the determination of column densities and cooling rates, and show that it produces more accurate results across a wide range of physical scenarios while retaining the computational efficiency of the original method. The tested models include spherical polytropes as well as disks with specified density and temperature profiles. We focus on applying our techniques within an SPH code, although our method can be implemented within any particle-based Lagrangian or grid-based Eulerian hydrodynamic scheme. Our new method may be applied in a broad range of situations, including within the realm of stellar interactions, collisions, and mergers.
Elucidating the biological basis for the reinforcing actions of alcohol in the mesolimbic dopamine system: the role of active metabolites of alcohol
Gerald A. Deehan Jr,Sheketha R. Hauser,Jessica A. Wilden,William A. Truitt,Zachary A. Rodd
Frontiers in Behavioral Neuroscience , 2013, DOI: 10.3389/fnbeh.2013.00104
Abstract: The development of successful pharmacotherapeutics for the treatment of alcoholism is predicated upon understanding the biological action of alcohol. A limitation of the alcohol research field has been examining the effects of alcohol only and ignoring the multiple biological active metabolites of alcohol. The concept that alcohol is a “pro-drug” is not new. Alcohol is readily metabolized to acetaldehyde within the brain. Acetaldehyde is a highly reactive compound that forms a number of condensation products, including salsolinol and iso-salsolinol (acetaldehyde and dopamine). Recent experiments have established that numerous metabolites of alcohol have direct CNS action, and could, in part or whole, mediate the reinforcing actions of alcohol within the mesolimbic dopamine system. The mesolimbic dopamine system originates in the ventral tegmental area (VTA) and projects to forebrain regions that include the nucleus accumbens (Acb) and the medial prefrontal cortex (mPFC) and is thought to be the neurocircuitry governing the rewarding properties of drugs of abuse. Within this neurocircuitry there is convincing evidence that; (1) biologically active metabolites of alcohol can directly or indirectly increase the activity of VTA dopamine neurons, (2) alcohol and alcohol metabolites are reinforcing within the mesolimbic dopamine system, (3) inhibiting the alcohol metabolic pathway inhibits the biological consequences of alcohol exposure, (4) alcohol consumption can be reduced by inhibiting/attenuating the alcohol metabolic pathway in the mesolimbic dopamine system, (5) alcohol metabolites can alter neurochemical levels within the mesolimbic dopamine system, and (6) alcohol interacts with alcohol metabolites to enhance the actions of both compounds. The data indicate that there is a positive relationship between alcohol and alcohol metabolites in regulating the biological consequences of consuming alcohol and the potential of alcohol use escalating to alcoholism.
Robotic-Assisted Laparoscopic Radical Prostatectomy: An Objective Assessment and Review of the Literature
Lester S. Borden Jr.,Paul M. Kozlowski
The Scientific World Journal , 2006, DOI: 10.1100/tsw.2006.400
Abstract:
Uniqueness for a boundary identification problem in thermal imaging
Kurt Bryan,Lester F. Caudill Jr.
Electronic Journal of Differential Equations , 1998,
Abstract: An inverse problem for an initial-boundary value problem is considered. The goal is to determine an unknown portion of the boundary of a region in ${mathbb R}^n$ from measurements of Cauchy data on a known portion of the boundary. The dynamics in the interior of the region are governed by a differential operator of parabolic type. Utilizing a unique continuation result for evolution operators, along with the method of eigenfunction expansions, it is shown that uniqueness holds for a large and physically reasonable class of Cauchy data pairs.
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