61,193 research outputs found

    Multi-centered D1-D5 solutions at finite B-moduli

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    We study the fate of two-centered D1-D5 systems on T^4 away from the singular supergravity point in the moduli space. We do this by considering a background D1-D5 black hole with a self-dual B-field moduli turned on and treating the second center in the probe limit in this background. We find that in general marginal bound states at zero moduli become metastable at finite B-moduli, demonstrating a breaking of supersymmetry. However, we also find evidence that when the charges of both centers are comparable, the effects of supersymmetry breaking become negligible. We show that this effect is independent of string coupling and thus it should be possible to reproduce this in the CFT at weak coupling. We comment on the implications for the fuzzball proposal.Comment: 19 pages + appendices, 14 figures; v2: added important remark in example in introduction, rewrote first paragraph in sect 3.2 for clarity, other misc. small edits; as accepted for publication in JHE

    Effect of Land Application of Poultry Waste on Pesticide Loss

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    The poultry industry in Arkansas is a large, concentrated, growing industry that produces a high volume of fecal waste. Most of this waste is surface applied as pasture fertilizer. Pesticides are commonly used in the poultry industry for fly and litter beetle contro land are often a component of the surface-applied poultry waste. No information exists in the scientific literature regarding the transport of this pesticide component to nearby water supplies.Our research focused on cyromazine, a feed-through larvicide used to control flies in caged-layer hen houses. Tetrachlorvinphos and carbaryl are also used in poultry waste, but these pesticides have a relatively low solubility in water and rapid decomposition rate. Cyromazine, however, is highly soluble and stable in water. Since it may be readily washed from the pasture by heavy rainfall and may persist in surface and soil water, cyromazine appears to be potentially a much greater long-term threat to water quality than either carbaryl or tetrachlorvinphos. Therefore, the objective of this investigation was to examine the extent of cyromazine loss as a result of land application of caged layer manure. To quantify cyromazine loss from pasture plots treated with caged layer manure,research was conducted at the University of Arkansas Agricultural Experiment Station at Fayetteville. Plots of uniform slope were bordered to isolate surface runoff, fitted with runoff collectors, and established in fescue pasture. Suction lysimeters were placed at the 60 cm depth to sample soil water in the unsaturated zone. Caged layer manure was analyzed for cyromazine concentration and applied to the plots at three different rates. Rainfall was applied by simulator at two intensities. Surface runoff and lysimeter samples were measured and analyzed for cyromazine concentration. A solid phase extraction procedure was used to separate the cyromazine from the water samples and analysis was done by high performance liquid chromatography (HPLC). Results showed that a heavier manure application increased both the runoff and cyromazine concentration. Higher rainfall intensity also increased total cyromazine loss in the runoff, but provided enough runoff volume to decrease the cyromazine concentration. Soil water from the unsaturated zone was monitored for a year following the manure application, but neither cyromazine nor its metabolite, melamine, were detected

    Quantum Surveying: How Entangled Pairs Act as Measuring Rods on Manifolds of Generalized Coherent States

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    Generalized coherent states arise from reference states by the action of locally compact transformation groups and thereby form manifolds on which there is an invariant measure. It is shown that this implies the existence of canonically associated Bell states that serve as measuring rods by relating the metric geometry of the manifold to the observed EPR correlations. It is further shown that these correlations can be accounted for by a hidden variable theory which is non-local but invariant under the stability group of the reference state.Comment: 14 pages, 0 figures, plain te

    Assessment of Effectiveness of Buffer Zones in Removing Impurities in Runoff from Areas Treated with Poultry Litter. Part II: Source Areas to Buffer Areas Ratio Effects

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    Vegetative filter strips (VFS) are known to reduce runoff losses of nutrients. solids. and other materials from land areas treated with fertilizers . Although VFS effectiveness is known to depend partially on the relative lengths of filter and pollutant source areas. there is little experimental evidence available to quantify this dependence. This is particularly the case when VFS are implemented down-slope of pasture areas treated with animal manures such as poultry litter. This study assessed the influences of pollutant source area (treated with poultry litter) and VFS lengths on VFS removal of total Kjeldahl nitrogen (TKN). ammonia nitrogen (NH3 -N ). nitrate nitrogen (N03-N). ortho-phosphorus (P04-P). total phosphorus (TP). total organic carbon (TOC). total suspended solids (TSS). and fecal coliform (FC) fromincoming runoff for a silt loam soil with fescue cover. Litter-treated lengths of 6.1. 12.2. and 18.3 m with corresponding VFS lengths of up to 18.3 m. 12.2 m. and 6.1 m. respectively, were examined. Runoff was produced from simulated rainfall applied at 50 mm/h for 1 h of runoff. Concentrations of the parameters analyzed were unaffected by litter treated length but demonstrated a first-order decrease with increasing VFS length except in the cases of TSS and FC. Mass transport of TKN. NH3-N. P04-P. and TP increased with increasing litter-treated length (due to increased runoff) and decreased (approximately first-order) with increasing VFS length. Effectiveness of the VFS in terms of TKN. NH3-N. P04 -P. and TP removal from runoff ranged from 6.5 to 96.3% depending on the particular parameter. litter-treated length. and VFS length. The data collected during this study can be helpful in developing and testing simulation models of VFS performance and can thus aid in design of VFS for pasture areas treated with poultry litter

    Flow alteration-ecology relationships in Ozark Highland streams: Consequences for fish, crayfish and macroinvertebrate assemblages

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    We examined flowalteration-ecology relationships in benthic macroinvertebrate, fish, and crayfish assemblages in Ozark Highland streams, USA, over two years with contrasting environmental conditions, a drought year (2012) and a flood year (2013). We hypothesized that: 1) there would be temporal variation in flow alteration-ecology relationships between the two years, 2) flow alteration-ecology relationshipswould be stronger during the drought year vs the flood year, and 3) fish assemblages would show the strongest relationships with flow alteration. We used a quantitative richest-targeted habitat (RTH) method and a qualitative multihabitat (QMH) method to collect macroinvertebrates at 16 USGS gaged sites during both years. We used backpack electrofishing to sample fish and crayfish at 17 sites in 2012 and 11 sites in 2013.Weused redundancy analysis to relate biological response metrics, including richness, diversity, density, and community-based metrics, to flow alteration.We found temporal variation in flow alteration-ecology relationships for all taxa, and that relationships differed greatly between assemblages. We found relationships were stronger for macroinvertebrates during the drought year but not for other assemblages, and that fish assemblage relationships were not stronger than the invertebrate taxa. Magnitude of average flow, frequency of high flow, magnitude of high flow, and duration of high flow were the most important categories of flow alteration metrics across taxa. Alteration of high and average flows was more important than alteration of low flows. Of 32 important flow alteration metrics across years and assemblages, 19 were significantly altered relative to expected values. Ecological responses differed substantially between drought and flood years, and this is likely to be exacerbated with predicted climate change scenarios. Differences in flow alteration-ecology relationships among taxonomic groups and temporal variation in relationships illustrate that a complex suite of variables should be considered for effective conservation of stream communities related to flow alteration

    Inverse cascades and resonant triads in rotating and stratified turbulence

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    Kraichnan’s seminal ideas on inverse cascades yielded new tools to study common phenomena in geophysical turbulent flows. In the atmosphere and the oceans, rotation and stratification result in a flow that can be approximated as two-dimensional at very large scales but which requires considering three-dimensional effects to fully describe turbulent transport processes and non-linear phenomena. Motions can thus be classified into two classes: fast modes consisting of inertia-gravity waves and slow quasi-geostrophic modes for which the Coriolis force and horizontal pressure gradients are close to balance. In this paper, we review previous results on the strength of the inverse cascade in rotating and stratified flows and then present new results on the effect of varying the strength of rotation and stratification (measured by the inverse Prandtl ratio N/f, of the Coriolis frequency to the Brunt-Väisäla frequency) on the amplitude of the waves and on the flow quasi-geostrophic behavior. We show that the inverse cascade is more efficient in the range of N/f for which resonant triads do not exist, /2≤N/f≤21/2≤N/f≤2. We then use the spatio-temporal spectrum to show that in this range slow modes dominate the dynamics, while the strength of the waves (and their relevance in the flow dynamics) is weaker.Fil: Oks, D.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Mininni, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Marino, R.. Universite Lyon 2; FranciaFil: Pouquet, A.. State University of Colorado Boulder; Estados Unido
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