102 research outputs found

    Collaboration in the Semantic Grid: a Basis for e-Learning

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    The CoAKTinG project aims to advance the state of the art in collaborative mediated spaces for the Semantic Grid. This paper presents an overview of the hypertext and knowledge based tools which have been deployed to augment existing collaborative environments, and the ontology which is used to exchange structure, promote enhanced process tracking, and aid navigation of resources before, after, and while a collaboration occurs. While the primary focus of the project has been supporting e-Science, this paper also explores the similarities and application of CoAKTinG technologies as part of a human-centred design approach to e-Learning

    A pilot randomized trial of a cognitive reappraisal obesity prevention program

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    Evaluate a selective obesity prevention program promoting use of cognitive reappraisals to reduce reward region response and increase inhibitory region response to high-fat/high-sugar foods and reduce intake of fat and sugar to prevent blunted reward region response to intake of such foods

    High performance dense linear algebra on a spatially distributed processor

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    As technology trends have limited the performance scaling of conventional processors, industry and academic research has turned to parallel architectures on a single chip, including distributed uniprocessors and multicore chips. This paper examines how to extend the archtypical operation of dense linear algebra, matrix multiply, to an emerging class of uniprocessor architectures characterized by a large number of independent functional units, register banks, and cache banks connected by a 2-D on-chip network. We extend the well known algorithm for matrix multiplication by Goto to this spatially distributed class of uniprocessor and describe the optimizations of the innermost kernel, a systolic-like algorithm running on a general purpose uniprocessor. The resulting implementation yields the first demonstration of high-performance in an application executing on the TRIPS processor hardware, a next-generation distributed processor core. We show that such processors are indeed capable of substantial improvements in single threaded performance provided their spatial topography is taken into account

    Nanoplankton : the dominant vector for carbon export across the Atlantic Southern Ocean in spring

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    DATA AND MATERIAL AVAILABILITY : The data used in this manuscript are available in the Zenodo data repository: 10.5281/zenodo.7820428. All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials.SUPPLEMENTARY MATERIAL : Supplementary Text; Figs. S1 to S4; Tables S1 and S2.Across the Southern Ocean, large (≥20 μm) diatoms are generally assumed to be the primary vector for carbon export, although this assumption derives mainly from summertime observations. Here, we investigated carbon production and export potential during the Atlantic Southern Ocean’s spring bloom from size-fractionated measurements of net primary production (NPP), nitrogen (nitrate, ammonium, urea) and iron (labile inorganic iron, organically complexed iron) uptake, and a high-resolution characterization of phytoplankton community composition. The nanoplankton-sized (2.7 to 20 μm) diatom, Chaetoceros spp., dominated the biomass, NPP, and nitrate uptake across the basin (40°S to 56°S), which we attribute to their low iron requirement, rapid response to increased light, and ability to escape grazing when aggregated into chains. We estimate that the spring Chaetoceros bloom accounted for >25% of annual export production across the Atlantic Southern Ocean, a finding consistent with recent observations from other regions highlighting the central role of the phytoplankton “middle class” in carbon export.The South African National Research Foundation, South African National Antarctic Programme, University of Cape Town Science Faculty Fellowship, University of Cape Town Vice-Chancellor Doctoral Research Scholarship, University of Cape Town Vice-Chancellor Future Leaders 2030 Award, European Union’s Horizon 2020 Research and Innovation Programme No. 844733, Academy of Finland, and Funds from an Anonymous Charitable Donor Trust as part of Whales and Climate Change Program.https://www.science.org/journal/sciadvhj2024GeneticsSDG-14:Life below wate

    The Atacama Cosmology Telescope: Extragalactic Sources at 148 GHz in the 2008 Survey

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    We report on extragalactic sources detected in a 455 square-degree map of the southern sky made with data at a frequency of 148 GHz from the Atacama Cosmology Telescope 2008 observing season. We provide a catalog of 157 sources with flux densities spanning two orders of magnitude: from 15 to 1500 mJy. Comparison to other catalogs shows that 98% of the ACT detections correspond to sources detected at lower radio frequencies. Three of the sources appear to be associated with the brightest cluster galaxies of low redshift X-ray selected galaxy clusters. Estimates of the radio to mm-wave spectral indices and differential counts of the sources further bolster the hypothesis that they are nearly all radio sources, and that their emission is not dominated by re-emission from warm dust. In a bright (>50 mJy) 148 GHz-selected sample with complete cross-identifications from the Australia Telescope 20 GHz survey, we observe an average steepening of the spectra between 5, 20, and 148 GHz with median spectral indices of α520=0.07±0.06\alpha_{\rm 5-20} = -0.07 \pm 0.06, α20148=0.39±0.04\alpha_{\rm 20-148} = -0.39 \pm0.04, and α5148=0.20±0.03\alpha_{\rm 5-148} = -0.20 \pm 0.03. When the measured spectral indices are taken into account, the 148 GHz differential source counts are consistent with previous measurements at 30 GHz in the context of a source count model dominated by radio sources. Extrapolating with an appropriately rescaled model for the radio source counts, the Poisson contribution to the spatial power spectrum from synchrotron-dominated sources with flux density less than 20 mJy is C^{\rm Sync} = (2.8 \pm 0.3) \times 10^{-6} \micro\kelvin^2.Comment: Accepted to Ap

    The Atacama Cosmology Telescope: A Measurement of the Cosmic Microwave Background Power Spectrum at 148 and 218 GHz from the 2008 Southern Survey

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    We present measurements of the cosmic microwave background (CMB) power spectrum made by the Atacama Cosmology Telescope at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. Our results clearly show the second through the seventh acoustic peaks in the CMB power spectrum. The measurements of these higher-order peaks provide an additional test of the {\Lambda}CDM cosmological model. At l > 3000, we detect power in excess of the primary anisotropy spectrum of the CMB. At lower multipoles 500 < l < 3000, we find evidence for gravitational lensing of the CMB in the power spectrum at the 2.8{\sigma} level. We also detect a low level of Galactic dust in our maps, which demonstrates that we can recover known faint, diffuse signals.Comment: 19 pages, 13 figures. Submitted to ApJ. This paper is a companion to Hajian et al. (2010) and Dunkley et al. (2010
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