800 research outputs found

    The Design and Instantiation of an Ontology for Teaching

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    In stark contrast with the fully participative "bazaar" imagery of open source software (OSS) development, recent empirical research has pointed out that much of the OSS development is carried out by a small percentage of developers. This raises serious concerns that concentration of development effort on a few will underutilize the available resources and limit innovation. I propose a model of concentration effects in OSS development that articulates the dynamics of individual and collective actions through which shared schemata emerges and that explores the subsequent impacts on innovation. I also examine the conditions for the emergence of shared schemata and introduce configural forms of concentration effects that may result. By examining the concentration effects on innovation, I seek to address a key knowledge-based question of how to organize efficiently to generate knowledge and problem-solving capability. Practitioners can use this approach to mine and evaluate online threaded discussions, and to better support existing knowledge-sharing initiatives. Dr. George Kuk's visit is funded by the HKU Constituent Theme - Information Technology.Dr George Kuk is a faculty member at the Nottingham University Business School. His research interests lie in problems that arise at the interface of strategy, organization and practice aspects of managing information systems and technology assets. His current research projects investigate participation and knowledge sharing in electronic networks of practice comprising of intra-organizational knowledge networks and open source software communities. His representative single-authored publications have appeared in Management Science, Information & Management, Government Information Quarterly and Group Dynamics.published_or_final_versionCentre for Information Technology in Education, University of Hong Kon

    In vivo precision of the GE Lunar iDXA for the measurement of visceral adipose tissue in adults: the influence of body mass index.

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    CoreScan is a new software for the GE Lunar iDXA, which provides a quantification of visceral adipose tissue (VAT). The objective of this study was to determine the in vivo precision of CoreScan for the measurement of VAT mass in a heterogeneous group of adults. Forty-five adults (aged 34.6 (8.6) years), ranging widely in body mass index (BMI 26.0 (5.2)  kg/m(2); 16.7-42.4 kg/m(2)), received two consecutive total body scans with repositioning. The sample was divided into two subgroups based on BMI, normal-weight and overweight/obese, for precision analyses. Subgroup analyses revealed that precision errors (RMSSD:%CV; root mean square standard deviation:% coefficient of variation) for VAT mass were 20.9 g:17.0% in the normal-weight group and 43.7 g:5.4% in overweight/obese groups. Our findings indicate that precision for DXA-VAT mass measurements increases with BMI, but caution should be used with %CV-derived precision error in normal BMI subjects.European Journal of Clinical Nutrition advance online publication, 15 October 2014; doi:10.1038/ejcn.2014.213

    Effects of eplerenone on resistance to antihypertensive medication in patients with primary or secondary hyperaldosteronism

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    Background and Objectives: Resistant hypertension is an important problem; nearly half of diagnosed hypertensives are not controlled to target blood pressure levels, and approximately 90% of strokes occur among patients with resistant hypertension. Primary aldosteronism accounts for approximately 20% of resistant hypertension, but the role of secondary hyperaldosteronism in resistant hypertension is seldom considered. We assessed the effects of eplerenone in patients with hypertension and either primary or secondary hyperaldosteronism. Methods: Patients with a history of resistant hypertension and a supine plasma aldosterone level ≥ 360 pmol/L were randomized to eplerenone versus placebo in a fully blinded study for one year. A medication intensity score was developed to assess the resistance of hypertension to medication (blood pressure × medication intensity). We assessed the effects of eplerenone on blood pressure and on resistance to concomitant medication. Results: Final results were available in 37 patients (19 on eplerenone and 18 on placebo). Resistance to medication, as assessed by the intensity of concomitant medication required to maintain blood pressure control, was markedly reduced by eplerenone: medication intensity scores declined by −0.50 ± 1.04 (SD) on placebo versus −2.11 ± 1.45 with eplerenone (P = 0.0001), the Systolic Resistance Score declined by −80.00 ± 122.93 on placebo versus −334.05 ± 21.73 on eplerenone (P = 0.0001), and the Diastolic Resistance Score increased by 1.28 ± 31.65 on placebo and declined by −40.74 ± 57.08 on eplerenone (P = 0.009). Conclusions: Eplerenone significantly reduced resistance to concomitant antihypertensive medication in both primary and secondary hyperaldosteronism

    Generalized priority-queue network dynamics: Impact of team and hierarchy

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    We study the effect of team and hierarchy on the waiting-time dynamics of priority-queue networks. To this end, we introduce generalized priority-queue network models incorporating interaction rules based on team-execution and hierarchy in decision making, respectively. It is numerically found that the waiting time distribution exhibits a power law for long waiting times in both cases, yet with different exponents depending on the team size and the position of queue nodes in the hierarchy, respectively. The observed power-law behaviors have in many cases a corresponding single or pairwise-interacting queue dynamics, suggesting that the pairwise interaction may constitute a major dynamics consequence in the priority-queue networks. It is also found that the reciprocity of influence is a relevant factor for the priority-queue network dynamic

    Results of the engineering run of the coherent neutrino nucleus interaction experiment (CONNIE)

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    The CONNIE detector prototype is operating at a distance of 30 m from the core of a 3.8 GWth nuclear reactor with the goal of establishing Charge-Coupled Devices (CCD) as a new technology for the detection of coherent elastic neutrino-nucleus scattering. We report on the results of the engineering run with an active mass of 4 g of silicon. The CCD array is described, and the performance observed during the first year is discussed. A compact passive shield was deployed around the detector, producing an order of magnitude reduction in the background rate. The remaining background observed during the run was stable, and dominated by internal contamination in the detector packaging materials. The in-situ calibration of the detector using X-ray lines from fluorescence demonstrates good stability of the readout system. The event rates with the reactor ON and OFF are compared, and no excess is observed coming from nuclear fission at the power plant. The upper limit for the neutrino event rate is set two orders of magnitude above the expectations for the standard model. The results demonstrate the cryogenic CCD-based detector can be remotely operated at the reactor site with stable noise below2 e RMS and stable background rates. The success of the engineering test provides a clear path for the upgraded 100 g detector to be deployed during 2016.Fil: Aguilar Arevalo, A.. Universidad Nacional Autónoma de México; MéxicoFil: Bertou, Xavier Pierre Louis. Comisión Nacional de Energía Atómica; Argentina. Comisión Nacional de Energía Atómica. Fundación José A. Balseiro; ArgentinaFil: Bonifazi, C.. Universidade Federal do Rio de Janeiro; BrasilFil: Butner, M.. Fermi National Accelerator Laboratory; Estados UnidosFil: Cancelo, G.. Fermi National Accelerator Laboratory; Estados UnidosFil: Castañeda Vazquez, A.. Universidad Nacional Autónoma de México; MéxicoFil: Cervantes Vergara, B.. Universidad Nacional Autónoma de México; MéxicoFil: Chavez, C. R.. Universidad Nacional de Asunción; ParaguayFil: Da Motta, H.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: D'Olivo, J. C.. Universidad Nacional Autónoma de México; MéxicoFil: Dos Anjos, J.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Estrada, J.. Fermi National Accelerator Laboratory; Estados UnidosFil: Fernández Moroni, Guillermo. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ford, R.. Fermi National Accelerator Laboratory; Estados UnidosFil: Foguel, A.. Centro Brasileiro de Pesquisas Físicas; Brasil. Universidade Federal do Rio de Janeiro; BrasilFil: Hernandez Torres, K. P.. Universidad Nacional Autónoma de México; MéxicoFil: Izraelevitch, F.. Fermi National Accelerator Laboratory; Estados UnidosFil: Kavner, A.. University of Michigan; Estados UnidosFil: Kilminster, B.. Universitat Zurich; SuizaFil: Kuk, K.. Fermi National Accelerator Laboratory; Estados UnidosFil: Lima Jr, H. P.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Makler, M.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Molina, J.. Universidad Nacional de Asunción; ParaguayFil: Moreno Granados, G.. Universidad Nacional Autónoma de México; MéxicoFil: Moro, Juan Manuel. Universidad Nacional del Sur. Departamento de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Paolini, Eduardo Emilio. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto ; ArgentinaFil: Sofo Haro, Miguel Francisco. Comision Nacional de Energia Atomica. Gerencia D/area de Energia Nuclear; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tiffenberg, Javier Sebastian. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Trillaud, F.. Universidad Nacional Autónoma de México; MéxicoFil: Wagner, S.. Centro Brasileiro de Pesquisas Físicas; Brasil. Pontificia Universidade Católica do Rio Grande do Sul; Brasi
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