74,748 research outputs found

    A Bait Attractant Study of the Nitidulidae (Coleoptera) at Shawnee State Forest in Southern Ohio

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    Four baits were tested for efficacy in attracting sap beetles (Nitidulidae) at two sites in the Shawnee State Forest over two collection periods in 1992. Species taken were categorized into three groups: abundant, moderate, and uncommon. At Site 1, nitidulids displayed a strong preference for whole wheat bread dough, followed by fermenting brown sugar, and fermenting malt/molasses solution, and vinegar, respectively. Site 2 collections showed a similar trend to Site 1, but the order of preference was switched for brown sugar and malt/molasses solution. Of the 20 species collected, six species were abundant, seven species were moderate, and seven species were locally uncommon

    Achieving Efficient Strong Scaling with PETSc using Hybrid MPI/OpenMP Optimisation

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    The increasing number of processing elements and decreas- ing memory to core ratio in modern high-performance platforms makes efficient strong scaling a key requirement for numerical algorithms. In order to achieve efficient scalability on massively parallel systems scientific software must evolve across the entire stack to exploit the multiple levels of parallelism exposed in modern architectures. In this paper we demonstrate the use of hybrid MPI/OpenMP parallelisation to optimise parallel sparse matrix-vector multiplication in PETSc, a widely used scientific library for the scalable solution of partial differential equations. Using large matrices generated by Fluidity, an open source CFD application code which uses PETSc as its linear solver engine, we evaluate the effect of explicit communication overlap using task-based parallelism and show how to further improve performance by explicitly load balancing threads within MPI processes. We demonstrate a significant speedup over the pure-MPI mode and efficient strong scaling of sparse matrix-vector multiplication on Fujitsu PRIMEHPC FX10 and Cray XE6 systems

    Vortex Loop Phase Transitions in Liquid Helium, Cosmic Strings, and High-T_c Superconductors

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    The distribution of thermally excited vortex loops near a superfluid phase transition is calculated from a renormalized theory. The number density of loops with a given perimeter is found to change from exponential decay with increasing perimeter to algebraic decay as T_c is approached, in agreement with recent simulations of both cosmic strings and high-T_c superconductors. Predictions of the value of the exponent of the algebraic decay at T_c and of critical behavior in the vortex density are confirmed by the simulations, giving strong support to the vortex-folding model proposed by Shenoy.Comment: Version to appear in Phys. Rev. Lett, with a number of corrections and addition

    The ground state of a spin-1/2 neutral particle with anomalous magnetic moment in a Aharonov-Casher configuration

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    We determine the (bound) ground state of a spin 1/2 chargless particle with anomalous magnetic moment in certain Aharonov-Casher configurations. We recast the description of the system in a supersymmetric form. Then the basic physical requirements for unbroken supersymmetry are established. We comment on the possibility of neutron trapping in these systems

    Exploring DCO+^+ as a tracer of thermal inversion in the disk around the Herbig Ae star HD163296

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    We aim to reproduce the DCO+^+ emission in the disk around HD163296 using a simple 2D chemical model for the formation of DCO+^+ through the cold deuteration channel and a parametric treatment of the warm deuteration channel. We use data from ALMA in band 6 to obtain a resolved spectral imaging data cube of the DCO+^+ JJ=3--2 line in HD163296 with a synthesized beam of 0."53×\times 0."42. We adopt a physical structure of the disk from the literature that reproduces the spectral energy distribution. We then apply a simplified chemical network for the formation of DCO+^+ that uses the physical structure of the disk as parameters along with a CO abundance profile, a constant HD abundance and a constant ionization rate. Finally, from the resulting DCO+^+ abundances, we calculate the non-LTE emission using the 3D radiative transfer code LIME. The observed DCO+^+ emission is reproduced by a model with cold deuteration producing abundances up to 1.6×10−111.6\times 10^{-11}. Warm deuteration, at a constant abundance of 3.2×10−123.2\times 10^{-12}, becomes fully effective below 32 K and tapers off at higher temperatures, reproducing the lack of DCO+^+ inside 90 AU. Throughout the DCO+^+ emitting zone a CO abundance of 2×10−72\times 10^{-7} is found, with ∌\sim99\% of it frozen out below 19 K. At radii where both cold and warm deuteration are active, warm deuteration contributes up to 20\% of DCO+^+, consistent with detailed chemical models. The decrease of DCO+^+ at large radii is attributed to a temperature inversion at 250 AU, which raises temperatures above values where cold deuteration operates. Increased photodesorption may also limit the radial extent of DCO+^+. The corresponding return of the DCO+^+ layer to the midplane, together with a radially increasing ionization fraction, reproduces the local DCO+^+ emission maximum at ∌\sim260 AU.Comment: 9 pages, 5 figures, accepted 7th July 201

    Growth Response to Carbadox in Pigs with a High or Low Genetic Capacity for Lean Tissue Growth

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    The impact of feeding carbadox from 12 to 75 pounds bodyweight on the rate, efficiency, and composition of growth in pigs with a high and low genetic capacity for lean tissue growth (LG) was evaluated. The high LG pigs gained bodyweight and muscle tissue faster and utilized feed more efficiently than low LG pigs. High LG pigs also had carcasses with more dissectible muscle and less dissectible fat. The pigs’ responses to carbadox feeding were dependent on the LG genotype. Feeding carbadox from 13 to 75 pounds bodyweight resulted in improved body growth and efficiency of feed utilization, but the magnitude of the responses were greater in the high LG pigs. Dietary carbadox additions from 13 to 75 pounds also resulted in greater muscle growth rates and carcass muscle content at 75 and 250 pounds in the high but not the low LG genotypes. Based on these data, the value of dietary agents such as carbadox that control or destroy antigens in the body need to be based on the impact of the agent on carcass composition as well as rate and efficiency of body growth. Furthermore, the value of the agent will be increased as pigs’ genetic capacity for lean tissue growth is increased

    Resolving the Surfaces of Extrasolar Planets With Secondary Eclipse Light Curves

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    We present a method that employs the secondary eclipse light curves of transiting extrasolar planets to probe the spatial variation of their thermal emission. This technique permits an observer to resolve the surface of the planet without the need to spatially resolve its central star. We evaluate the feasibility of this technique for the HD 209458 system [..]. We consider two representations of the planetary thermal emission; a simple model parameterized by a sinusoidal dependence on longitude and latitude, as well as the results of a three-dimensional dynamical simulation of the planetary atmosphere previously published by Cooper & Showman. We find that observations of the secondary eclipse light curve are most sensitive to a longitudinal offset in the geometric and photometric centroids of the hemisphere of the planet visible near opposition. To quantify this signal, we define a new parameter, the ``uniform time offset,'' which measures the time lag between the observed secondary eclipse and that predicted by a planet with a uniform surface flux distribution. We compare the predicted amplitude of this parameter for HD 209458 with the precision with which it could be measured with IRAC. We find that IRAC observations at 3.6um a single secondary eclipse should permit sufficient precision to confirm or reject the Cooper & Showman model of the surface flux distribution for this planet. We quantify the signal-to-noise ratio for this offset in the remaining IRAC bands (4.5um, 5.8um, and 8.0um), and find that a modest improvement in photometric precision (as might be realized through observations of several eclipse events) should permit a similarly robust detection.Comment: AASTeX 5.2, 24 pages, 5 figures, accepted for publication in ApJ; v2: clarifications, updated to version accepted by ApJ; v3: try to reduce spacin

    Distinct emphysema subtypes defined by quantitative CT analysis are associated with specific pulmonary matrix metalloproteinases.

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    BACKGROUND: Emphysema is characterised by distinct pathological sub-types, but little is known about the divergent underlying aetiology. Matrix-metalloproteinases (MMPs) are proteolytic enzymes that can degrade the extracellular matrix and have been identified as potentially important in the development of emphysema. However, the relationship between MMPs and emphysema sub-type is unknown. We investigated the role of MMPs and their inhibitors in the development of emphysema sub-types by quantifying levels and determining relationships with these sub-types in mild-moderate COPD patients and ex/current smokers with preserved lung function. METHODS: Twenty-four mild-moderate COPD and 8 ex/current smokers with preserved lung function underwent high resolution CT and distinct emphysema sub-types were quantified using novel local histogram-based assessment of lung density. We analysed levels of MMPs and tissue inhibitors of MMPs (TIMPs) in bronchoalveolar lavage (BAL) and assessed their relationship with these emphysema sub-types. RESULTS: The most prevalent emphysema subtypes in COPD subjects were mild and moderate centrilobular (CLE) emphysema, while only small amounts of severe centrilobular emphysema, paraseptal emphysema (PSE) and panlobular emphysema (PLE) were present. MMP-3, and -10 associated with all emphysema sub-types other than mild CLE, while MMP-7 and -8 had associations with moderate and severe CLE and PSE. MMP-9 also had associations with moderate CLE and paraseptal emphysema. Mild CLE occurred in substantial quantities irrespective of whether airflow obstruction was present and did not show any associations with MMPs. CONCLUSION: Multiple MMPs are directly associated with emphysema sub-types identified by CT imaging, apart from mild CLE. This suggests that MMPs play a significant role in the tissue destruction seen in the more severe sub-types of emphysema, whereas early emphysematous change may be driven by a different mechanism. TRIAL REGISTRATION: Trial registration number NCT01701869
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