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Search Results: 1 - 10 of 260093 matches for " D. W.;Miller "
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Morphology offers no clues to asexual vs. sexual origin of small Acropora cervicornis (Scleractinia: Acroporidae) colonies
Williams,D. E; Miller,M. W;
Revista de Biología Tropical , 2006,
Abstract: sexual recruitment of the staghorn coral, acropora cervicornis, is accepted to be very rare. instead, these branching corals proliferate through fragmentation leading to dense mono-specific and possibly monoclonal stands. for acroporid corals, which have suffered drastic population declines, dominance of asexual reproduction results in low levels of genotypic diversity and limited ability to re-colonize extirpated areas. small colonies with a single encrusting, symmetrical base, and few incipient branches are frequently presumed to be the result of a settled planula (i.e. sexual reproduction). here, we show that colonies fitting this description (i.e., presumed sexual recruits) can result from asexual fragmentation. acropora cervicornis colonies (~20 cm diameter) were tagged and observed over eighteen months. in several cases, colony offshoots fused with the adjacent substrate forming secondary disc-like attachment points. following natural fragmentation, these discs of tissue became separated from the original colony, and were observed to heal and give rise to smaller colonies with striking similarity to the expected morphology of a sexual recruit. thus, presuming a colony is a sexual recruit based on appearance is unreliable and may lead to inflated expectations of genetic diversity among populations. the accurate assessment of recruitment and genetic diversity is crucial to predicting the recovery potential of these imperiled and ecologically irreplaceable reef corals. rev. biol. trop. 54 (suppl. 3): 145-151. epub 2007 jan. 15.
Morphology offers no clues to asexual vs. sexual origin of small Acropora cervicornis (Scleractinia: Acroporidae) colonies
D. E Williams,M. W Miller
Revista de Biología Tropical , 2006,
Abstract: Sexual recruitment of the staghorn coral, Acropora cervicornis, is accepted to be very rare. Instead, these branching corals proliferate through fragmentation leading to dense mono-specific and possibly monoclonal stands. For acroporid corals, which have suffered drastic population declines, dominance of asexual reproduction results in low levels of genotypic diversity and limited ability to re-colonize extirpated areas. Small colonies with a single encrusting, symmetrical base, and few incipient branches are frequently presumed to be the result of a settled planula (i.e. sexual reproduction). Here, we show that colonies fitting this description (i.e., presumed sexual recruits) can result from asexual fragmentation. Acropora cervicornis colonies (~20 cm diameter) were tagged and observed over eighteen months. In several cases, colony offshoots fused with the adjacent substrate forming secondary disc-like attachment points. Following natural fragmentation, these discs of tissue became separated from the original colony, and were observed to heal and give rise to smaller colonies with striking similarity to the expected morphology of a sexual recruit. Thus, presuming a colony is a sexual recruit based on appearance is unreliable and may lead to inflated expectations of genetic diversity among populations. The accurate assessment of recruitment and genetic diversity is crucial to predicting the recovery potential of these imperiled and ecologically irreplaceable reef corals. Rev. Biol. Trop. 54 (Suppl. 3): 145-151. Epub 2007 Jan. 15. Se ha aceptado que el reclutamiento sexual del coral asta de venado, Acropora cervicornis, es muy raro. Por el contrario, estos corales ramificados proliferan a través de fragmentación, generando densas bases monoespecíficas e incluso monoclonales. Para corales acropóridos, los cuales han sufrido disminuciones de población drásticas, la dominancia de reproducción asexual resulta en bajos niveles de diversidad genotípica y abilidad limitada para recolonizar áreas de donde han sido erradicados. Frecuentemente se presume que las colonias peque as con una sola base incrustante simétrica y unas pocas ramas incipientes, son el resultado del asentamiento de una plánula (reproducción sexual). Aquí, nosotros demostramos que algunas colonias que calzan con esta descripción (supuesta reproducción sexual) pueden resultar de fragmentación asexual. Se etiquetaron y observaron colonias de Acropora cervicornis (~20 cm de diámetro) durante 18 meses. En muchos casos, los reto os de la colonia se fusionaron con el sustrato adyacente formando pun
Mesoscale predictability under various synoptic regimes
W. A. Nuss,D. K. Miller
Nonlinear Processes in Geophysics (NPG) , 2001,
Abstract: Numerical model experiments using slightly rotated terrain are compared to gauge the sentivity of mesoscale forecasts to small perturbations that arise due to small synoptic-scale wind direction errors relative to topographic features. The surface and above surface wind speed errors, as well as the precipitation forecast errors, are examined for a landfalling cold front that occurred during the California Landfalling Jets (CALJET) experiment. The slight rotation in the terrain results in nearly identical synoptic-scale forecasts, but result in substantial forecast errors on the mesoscale in both wind and precipitation. The largest mesoscale errors occur when the front interacts with the topography, which feeds back on the frontal dynamics to produce differing frontal structures, which, in turn, result in mesoscale errors as large as 40% (60%) of the observed mesoscale variability in rainfall (winds). This sensitivity differs for the two rotations and a simple average can still have a substantial error. The magnitude of these errors is very large given the size of the perturbation, which raises concerns about the predictability of the detailed mesoscale structure for landfalling fronts.
The One-loop QCD Corrections for $γ^* to Q\bar Q q\bar q$
E. W. N. Glover,D. J. Miller
Physics , 1996, DOI: 10.1016/S0370-2693(97)00113-5
Abstract: We calculate the one-loop QCD corrections for the decay of an off-shell vector boson with vector couplings into two pairs of quarks of equal or unequal flavours keeping all orders in the number of colours. These matrix elements are relevant for the calculation of the next-to-leading order ${\cal O}(\alpha_s^3)$ corrections to four jet production in electron-positron annihilation, the production of a gauge boson accompanied by two jets in hadron-hadron collisions and three jet production in deep inelastic scattering. We use standard techniques for computing the interference of one-loop and tree level Feynman diagrams, but organise the results in terms of combinations of scalar loop integrals that are finite in the limit of vanishing Gram determinants and are therefore numerically stable.
An Overset Grid Method for Fluid-Structure Interaction  [PDF]
Scott T. Miller, R. L. Campbell, C. W. Elsworth, J. S. Pitt, D. A. Boger
World Journal of Mechanics (WJM) , 2014, DOI: 10.4236/wjm.2014.47023
Abstract:

An overset grid methodology is developed for the fully coupled analysis of fluid-structure interaction (FSI) problems. The overset grid approach alleviates some of the computational geometry difficulties traditionally associated with Arbitrary-Lagrangian-Eulerian (ALE) based, moving mesh methods for FSI. Our partitioned solution algorithm uses separate solvers for the fluid (finite volume method) and the structure (finite element method), with mesh motion computed only on a subset of component grids of our overset grid assembly. Our results indicate a significant reduction in computational cost for the mesh motion, and element quality is improved. Numerical studies of the benchmark test demonstrate the benefits of our overset mesh method over traditional approaches.

Techniques for the Synthesis of Reversible Toffoli Networks
D. Maslov,D. M. Miller,G. W. Dueck
Physics , 2006, DOI: 10.1145/1278349.1278355
Abstract: This paper presents novel techniques for the synthesis of reversible networks of Toffoli gates, as well as improvements to previous methods. Gate count and technology oriented cost metrics are used. Our synthesis techniques are independent of the cost metrics. Two new iterative synthesis procedure employing Reed-Muller spectra are introduced and shown to complement earlier synthesis approaches. The template simplification suggested in earlier work is enhanced through introduction of a faster and more efficient template application algorithm, updated (shorter) classification of the templates, and presentation of the new templates of sizes 7 and 9. A novel ``resynthesis'' approach is introduced wherein a sequence of gates is chosen from a network, and the reversible specification it realizes is resynthesized as an independent problem in hopes of reducing the network cost. Empirical results are presented to show that the methods are effective both in terms of the realization of all 3x3 reversible functions and larger reversible benchmark specifications.
Quantum Circuit Simplification and Level Compaction
D. Maslov,G. W. Dueck,D. M. Miller,C. Negrevergne
Physics , 2006, DOI: 10.1109/TCAD.2007.911334
Abstract: Quantum circuits are time dependent diagrams describing the process of quantum computation. Usually, a quantum algorithm must be mapped into a quantum circuit. Optimal synthesis of quantum circuits is intractable and heuristic methods must be employed. With the use of heuristics, the optimality of circuits is no longer guaranteed. In this paper, we consider a local optimization technique based on templates to simplify and reduce the depth of non-optimal quantum circuits. We present and analyze templates in the general case, and provide particular details for the circuits composed of NOT, CNOT and controlled-sqrt-of-NOT gates. We apply templates to optimize various common circuits implementing multiple control Toffoli gates and quantum Boolean arithmetic circuits. We also show how templates can be used to compact the number of levels of a quantum circuit. The runtime of our implementation is small while the reduction in number of quantum gates and number of levels is significant.
Loss of Propiconazole and Its Four Stereoisomers from the Water Phase of Two Soil-Water Slurries as Measured by Capillary Electrophoresis
Arthur W. Garrison,Jimmy K. Avants,Rebecca D. Miller
International Journal of Environmental Research and Public Health , 2011, DOI: 10.3390/ijerph8083453
Abstract: Propiconazole is a chiral fungicide used in agriculture for control of many fungal diseases on a variety of crops. This use provides opportunities for pollution of soil and, subsequently, groundwater. The rate of loss of propiconazole from the water phase of two different soil-water slurries spiked with the fungicide at 50 mg/L was followed under aerobic conditions over five months; the t 1/2 was 45 and 51 days for the two soil slurries. To accurately assess environmental and human risk, it is necessary to analyze the separate stereoisomers of chiral pollutants, because it is known that for most such pollutants, both biotransformation and toxicity are likely to be stereoselective. Micellar electrokinetic chromatography (MEKC), the mode of capillary electrophoresis used for analysis of neutral chemicals, was used for analysis of the four propiconazole stereoisomers with time in the water phase of the slurries. MEKC resulted in baseline separation of all stereoisomers, while GC-MS using a chiral column gave only partial separation. The four stereoisomers of propiconazole were lost from the aqueous phase of the slurries at experimentally equivalent rates, i.e., there was very little, if any, stereoselectivity. No loss of propiconazole was observed from the autoclaved controls of either soil, indicating that the loss from active samples was most likely caused by aerobic biotansformation, with a possible contribution by sorption to the non-autoclaved active soils. MEKC is a powerful tool for separation of stereoisomers and can be used to study the fate and transformation kinetics of chiral pesticides in water and soil.
Dynamics of the Vaginal Ecosystem—Hormonal Influences
Miranda A. Farage, Kenneth W. Miller and Jack D. Sobel
Infectious Diseases: Research and Treatment , 2012, DOI: 10.4137/IDRT.S3903
Abstract: The vagina is a dynamic and finely tuned ecosystem in which homeostasis depends on mutually beneficial interactions between a human female and her resident microorganisms, an ecosystem that can be thrown off balance by a wide variety of both intrinsic and extrinsic factors. Although a functional equilibrium provides stability to the ecosystem considered crucial to maintaining vaginal health, “normal flora” is a concept currently being redefined. New methodologies enable molecular analyses of the vaginal microbiota which have widened the definition of “normal” from a single specific microbiological profile to a range of functional microbial equilibria dependent upon pertinent host and microbial factors. One of the strongest influences on the vaginal microbiota is the hormonal changes that define the reproductive phases of a woman’s life. The vaginal environment is particularly responsive to estrogen, a hormone that creates distinctive changes in the vaginal microbiota. This review summarizes the components of a healthy vaginal ecosystem during the reproductive years, including the characteristics of a healthy equilibrium and factors that can disturb a functional balance. It also summarizes what is known about the vaginal microbiota in childhood and after menopause. Healthful ecosystems at any stage of a female’s reproductive life will be characterized by a microbiota that both maintains physiological function and though changeable, adapts to normal perturbation without succumbing to disease.
Spin-polarized high-energy scattering of charged leptons on nucleons
Burkardt, M.;Miller, C. A.;Nowak, W. -D.
High Energy Physics - Phenomenology , 2008,
Abstract: The proton is a composite object with spin one-half, understood to contain highly relativistic spin one-half quarks exchanging spin-one gluons, each possibly with significant orbital angular momenta. While their fundamental interactions are well described by Quantum ChromoDynamics (QCD), our standard theory of the strong interaction, nonperturbative calculations of the internal structure of the proton based directly on QCD are beginning to provide reliable results. Most of our present knowledge of the structure of the proton is based on experimental measurements interpreted within the rich framework of QCD. An area presently attracting intense interest, both experimental and theoretical, is the relationship between the spin of the proton and the spins and orbital angular momenta of its constituents. While remarkable progress has been made, especially in the last decade, the discovery and investigation of new concepts have revealed that much more remains to be learned. This progress is reviewed and an outlook for the future is offered.
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