3,775 research outputs found

    Dealing with the Media

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    As a research administrator, I believe totally in the validity of our research mission and goals. These goals are consistent with and in the best interest of our tax-paying citizens. (Papers from the National Agricultural Science Information Conference, Ames, Iowa.

    An investigation of the performance portability of OpenCL

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    This paper reports on the development of an MPI/OpenCL implementation of LU, an application-level benchmark from the NAS Parallel Benchmark Suite. An account of the design decisions addressed during the development of this code is presented, demonstrating the importance of memory arrangement and work-item/work-group distribution strategies when applications are deployed on different device types. The resulting platform-agnostic, single source application is benchmarked on a number of different architectures, and is shown to be 1.3ā€“1.5Ɨ slower than native FORTRAN 77 or CUDA implementations on a single node and 1.3ā€“3.1Ɨ slower on multiple nodes. We also explore the potential performance gains of OpenCLā€™s device fissioning capability, demonstrating up to a 3Ɨ speed-up over our original OpenCL implementation

    A selected ion flow tube study of the reactions of gas-phase cations with PSCl3

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    A selected ion flow tube was used to investigate the positive ion chemistry of thiophosphoryl chloride, PSCl3_3. Rate coefficients and ion product branching ratios have been determined at room temperature for reactions with nineteen cations ; H3_3O+^+, CF3+_3^+, CF+^+, NO+^+, NO2+_2^+, SF2+_2^+, SF+^+, CF2+_2^+, O2+_2^+, H2_2O+^+, N2_2O+^+, O+^+, CO2+_2^+, CO+^+, N+^+, N2+_2^+, Ar+^+, F+^+ and Ne+^+ (in order of increasing recombination energy). Complementary data described in the previous paper have been obtained for this molecule via the observation of threshold photoelectron photoion coincidences. For ions whose recombination energies are in the range 10-22 eV, comparisons are made between the product ion branching rations of PSCl3_3 from photoionisation and from ion-molecule reactions. In most instances, the data from the two experiments are well correlated, suggesting that long-range charge transfer is the dominant mechanism for these ion-molecule reactions ; the agreement is particularly good for the atomic ions Ar+^+, F+^+ and Ne+^+. Some reactions (e.g. O2+_2^+ + PSCl3_3), however, exhibit significant differences; short-range charge transfer must then be occurring following the formation of an ion-molecule complex. For ions whose recombination energies are less than 10 eV (i.e. H3_3O+^+, CF3+_3^+, CF+^+ and NO+^+), reactions can only occur via a chemical process in which bonds are broken and formed, because the recombination energy of the cation is less than the ionisation energy of PSCl3_3

    Predictive analysis of a hydrodynamics application on large-scale CMP clusters

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    We present the development of a predictive performance model for the high-performance computing code Hydra, a hydrodynamics benchmark developed and maintained by the United Kingdom Atomic Weapons Establishment (AWE). The developed model elucidates the parallel computation of Hydra, with which it is possible to predict its runtime and scaling performance on varying large-scale chip multiprocessor (CMP) clusters. A key feature of the model is its granularity; with the model we are able to separate the contributing costs, including computation, point-to-point communications, collectives, message buffering and message synchronisation. The predictions are validated on two contrasting large-scale HPC systems, an AMD Opteron/ InfiniBand cluster and an IBM BlueGene/P, both of which are located at the Lawrence Livermore National Laboratory (LLNL) in the US. We validate the model on up to 2,048 cores, where it achieves a > 85% accuracy in weak-scaling studies. We also demonstrate use of the model in exposing the increasing costs of collectives for this application, and also the influence of node density on network accesses, therefore highlighting the impact of machine choice when running this hydrodynamics application at scale

    Women and urban environments, volume 1 : feminist analysis of urban spaces

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    vii, 58 p. : ill

    Feasibility of National Surveillance of Health-Care-Associated Infections in Home-Care Settings

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    This article examines the rationale and strategies for surveillance of health-care-associated infections in home-care settings, the challenges of nonhospital-based surveillance, and the feasibility of developing a national surveillance system

    Economic Analysis of Year-long Grazing Rate Studies on Substation No. 14, Near Sonora.

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    8 p

    Marketing Aspects of Range Sheep Production in Texas.

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    20 p
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