2,829 research outputs found

    Precise Determination of the Neutron Magnetic Form Factor to Higher Q2Q^2

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    The neutron elastic magnetic form factor GMnG_M^n has been extracted from quasielastic scattering from deuterium in the CEBAF Large Acceptance Spectrometer, CLAS. The kinematic coverage of the measurement is continuous over a broad range, extending from below 1 GeV2GeV^2 to nearly 5 GeV2GeV^2 in four-momentum transfer squared. High precision is achieved by employing a ratio technique in which most uncertainties cancel, and by a simultaneous in-situ calibration of the neutron detection efficiency, the largest correction to the data. Preliminary results are shown with statistical errors only.Comment: Contribution to the proceedings of the Tenth International Conference on Baryons (2004), to be published in Nuclear Physics, Section

    AIDS: A Brief Overview

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    By the late 1970\u27s an epidemic begun in Central Africa which spread world wide by the mid 1980\u27s

    Factorization of weakly compact operators between Banach spaces and Fréchet or (LB)-spaces

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    [EN] In this note we show that weakly compact operators from a Banach space X into a complete (LB)-space E need not factorize through a reflexive Banach space. If E is a Fréchet space, then weakly compact operators from a Banach space X into E factorize through a reflexive Banach space. The factorization of operators from a Fréchet or a complete (LB)-space into a Banach space mapping bounded sets into relatively weakly compact sets is also investigated.The research of the first author was partially supported by MEC and FEDER Project MTM2010-15200 and by GV Project Prometeo/2008/101. The support of the University of Aberdeen and the Universidad Polit´ecnica of Valencia is gratefully acknowledged.Bonet Solves, JA.; Wright, JM. (2012). Factorization of weakly compact operators between Banach spaces and Fréchet or (LB)-spaces. Matematicki Vesnik. 64(4):330-335. http://hdl.handle.net/10251/58753S33033564

    The Power of Convening: Towards an Understanding of Artist-Led Collective Practice as a Convener of Place

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    In recent years, there has been a growing interest in artist-led collectives with high-profile recognition within contemporary art mega festivals, prizes, and biennials. Yet, these amorphous entities and initiatives tend to be framed either through their politically motivated actions or as a critique of the notion of the single author or ‘artist-as-genius’ mythology. This article builds upon this discourse to shift the emphasis onto both interpersonal and socio-political relationships that constitute artist-led collectives in order to explore their complex role in convening and placemaking and what this might mean for both policymaking and research

    Testing the extraction of past seawater Nd isotopic composition from North Atlantic deep sea sediments and foraminifera

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    Neodymium isotopes provide a paleoceanographic proxy for past deep water circulation and local weathering changes and have been measured on various authigenic marine sediment components, including fish teeth, ferromanganese oxides extracted by acid-reductive leaching, cleaned foraminifera, and foraminifera with Fe-Mn oxide coatings. Here we compare Nd isotopic measurements obtained from ferromanganese oxides leached from bulk sediments and planktonic foraminifera, as well as from oxidatively-reductively cleaned foraminiferal shells from sediment cores in the North Atlantic. Sedimentary volcanic ash contributes a significant fraction of the Nd when the ferro-manganese (Fe-Mn) oxide coatings are leached from bulk sediments. Reductive leachates of marine sediments from North Atlantic core tops near Iceland, or directly downstream from Iceland-Scotland Overflow Waters, record ɛNd values that are significantly higher than seawater, indicating that volcanic material is easily leached by acid-reductive methods. The ɛNd values from sites more distal to Iceland are similar to modern seawater values, showing little contamination from Iceland-derived volcanogenic material. In all comparisons, core top planktonic foraminifera ɛNd values more closely approximate modern deep seawater than the bulk sediment reductive leached value suggesting that the foraminifera provide a route toward quantifying the Nd isotopic signature of deep North Atlantic water masses

    A comparative assessment of waste incinerators in the UK

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    The uptake in Europe of Energy from Waste (EfW) incinerator plants has increased rapidly in recent years. In the UK, 25 municipal waste incinerators with energy recovery are now in operation; however, their waste supply chains and business practices vary significantly. With over a hundred more plant developments being considered it is important to establish best business practices for ensuring efficient environmental and operational performance. By reviewing the 25 plants we identify four suitable case study plants to compare technologies (moving grate, fluidised bed and rotary kiln), plant economics and operations. Using data collected from annual reports and through interviews and site visits we provide recommendations for improving the supply chain for waste incinerators and highlight the current issues and challenges faced by the industry. We find that plants using moving grate have a high availability of 87-92%. However, compared to the fluidised bed and rotary kiln, quantities of bottom ash and emissions of hydrogen chloride and carbon monoxide are high. The uptake of integrated recycling practices, combined heat and power, and post incineration non-ferrous metal collections needs to be increased among EfW incinerators in the UK. We conclude that one of the major difficulties encountered by waste facilities is the appropriate selection of technology, capacity, site, waste suppliers and heat consumers. This study will be of particular value to EfW plant developers, government authorities and researchers working within the sector of waste management

    Climate Modification of Dry Desert Air by a Large Irrigation Project

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    Climatic changes caused by the evapotranspiration of large amounts of irrigation water may be important in irrigation scheduling, weather forecasting and the management of irrigated farmland. Results from previous studies are often in disagreement as to the magnitude of climatic modification by irrigation. Some studies show only minimal changes (Fritschen and Nixon, 1967, Fowler and Helvey, 1974) and others show sizeable modifications (Davenport and Hudson, 1967). Beebe (1974) reports that severe storms as indicated by tornado's are more prevalent over irrigated land in Texas. A recent statistical report (Schickendanz, 1976) shows rainfall increases, temperature anomalities, and hail increases, all caused by irrigation. Schickendanz work covered a very large area in the Great Plains of the United States. Previously reported studies differ greatly in size of area involved and objectives. The studies reported here had the objective of showing the possible climate modification caused by a large irrigation project in Idaho surrounded by a nonirrigated sagebrush grass desert

    Magnetic fluctuations and spin freezing in nonsuperconducting LiFeAs derivatives

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    We present detailed magnetometry and muon-spin rotation data on polycrystalline samples of overdoped, nonsuperconducting LiFe1−xNixAs (x = 0.1,0.2) and Li1−yFe1+yAs (0 y 0.04) as well as superconducting LiFeAs.While LiFe1−xNixAs exhibits weak antiferromagnetic fluctuations down to 1.5 K,Li1−yFe1+yAs samples, which have a much smaller deviation from the 1 : 1 : 1 stoichiometry, show a crossover from ferromagnetic to antiferromagnetic fluctuations on cooling and a freezing of dynamically fluctuating moments at low temperatures. We do not find any signatures of time-reversal symmetry breaking in stoichiometric LiFeAs that would support recent predictions of triplet pairing

    Exercise Training Reduces Liver Fat and Increases Rates of VLDL Clearance, but not VLDL Production in NAFLD

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    Context Randomised controlled trials in non-alcoholic fatty liver disease (NAFLD) have shown that regular exercise, even without calorie restriction, reduces liver steatosis. A previous study has shown that 16 weeks supervised exercise training in NAFLD did not affect total VLDL kinetics. Objective To determine the effect of exercise training on intrahepatocellular fat (IHCL) and the kinetics of large triglyceride-(TG)-rich VLDL1 and smaller denser VLDL2 which has a lower TG content. Design A 16 week randomised controlled trial. Patients 27 sedentary patients with NAFLD. Intervention Supervised exercise with moderate-intensity aerobic exercise or conventional lifestyle advice (control). Main outcome Very low density lipoprotein1 (VLDL1) and VLDL2-TG and apolipoproteinB (apoB) kinetics investigated using stable isotopes before and after the intervention. Results In the exercise group VO2max increased by 31±6% (mean±SEM) and IHCL decreased from 19.6% (14.8, 30.0) to 8.9% (5.4, 17.3) (median (IQR)) with no significant change in VO2max or IHCL in the control group (change between groups p<0.001 and p=0.02, respectively). Exercise training increased VLDL1-TG and apoB fractional catabolic rates, a measure of clearance, (change between groups p=0.02 and p=0.01, respectively), and VLDL1-apoB production rate (change between groups p=0.006), with no change in VLDL1 -TG production rate. Plasma TG did not change in either group. Conclusion An increased clearance of VLDL1 may contribute to the significant decrease in liver fat following 16 weeks of exercise in NAFLD. A longer duration or higher intensity exercise interventions may be needed to lower plasma TG and VLDL production rate

    Testing Broken U(1) Symmetry in a Two-Component Atomic Bose-Einstein Condensate

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    We present a scheme for determining if the quantum state of a small trapped Bose-Einstein condensate is a state with well defined number of atoms, a Fock state, or a state with a broken U(1) gauge symmetry, a coherent state. The proposal is based on the observation of Ramsey fringes. The population difference observed in a Ramsey fringe experiment will exhibit collapse and revivals due to the mean-field interactions. The collapse and revival times depend on the relative strength of the mean-field interactions for the two components and the initial quantum state of the condensate.Comment: 20 Pages RevTex, 3 Figure
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