178 research outputs found

    Performance of the Electromagnetic Calorimeter of the HERMES Experiment

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    The performance of the electromagnetic calorimeter of the HERMES experiment is described. The calorimeter consists of 840 radiation resistant F101 lead-glass counters. The response to positrons up to 27.5 GeV, the comparison between the measured energy and the momentum reconstructed from tracking, long-term stability, hadron rejection and neutral meson invariant mass reconstruction are shown.Comment: 22 pages, 13 figures, LaTeX, accepted by NI

    On Second-Order Monadic Monoidal and Groupoidal Quantifiers

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    We study logics defined in terms of second-order monadic monoidal and groupoidal quantifiers. These are generalized quantifiers defined by monoid and groupoid word-problems, equivalently, by regular and context-free languages. We give a computational classification of the expressive power of these logics over strings with varying built-in predicates. In particular, we show that ATIME(n) can be logically characterized in terms of second-order monadic monoidal quantifiers

    Is the metabolic cost of walking higher in people with diabetes?

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    People with diabetes walk slower and display biomechanical gait alterations compared with controls, but it remains unknown whether the metabolic cost of walking (CoW) is elevated. The aim of this study was to investigate the CoW and the lower limb concentric joint work as a major determinant of the CoW, in patients with diabetes and diabetic peripheral neuropathy (DPN). Thirty-one nondiabetic controls (Ctrl), 22 diabetic patients without peripheral neuropathy (DM), and 14 patients with moderate/severe DPN underwent gait analysis using a motion analysis system and force plates and treadmill walking using a gas analyzer to measure oxygen uptake. The CoW was significantly higher particularly in the DPN group compared with controls and also in the DM group (at selected speeds only) compared with controls, across a range of matched walking speeds. Despite the higher CoW in patients with diabetes, concentric lower limb joint work was significantly lower in DM and DPN groups compared with controls. The higher CoW is likely due to energetic inefficiencies associated with diabetes and DPN reflecting physiological and biomechanical characteristics. The lower concentric joint work in patients with diabetes might be a consequence of kinematic gait alterations and may represent a natural strategy aimed at minimizing the CoW

    EURRECA's General Framework to make the process of setting up micronutrient recommendations explicit and transparent

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    EURRECA is a Network of Excellence with the objective of addressing the problem of national variations in micronutrient recommendations and working towards a framework of advice to better inform policy-makers. It became apparent that the network needed a framework that puts the process of recommendation setting in the context of science, policy and society. Although variability in recommendations originates from the scientific evidence-base used and its interpretation (e.g. health outcomes, types and methods of evaluation of evidence, quantification of risk/benefit), the background information provided in the recommendation reports does not easily facilitate the disentangling of the relative contribution of these different aspects because of lack of transparency. The present report portrays the general framework (see Figure) that has been developed by and for EURRECA in order to make the process of setting up micronutrient recommendations explicit and transparent. In explaining the link from science to policy applications, the framework distinguishes four principal components or stages (see Figure). These stages are: a) Defining the nutrient requirements: A judgement about the (best) distribution(s) of the population requirement is necessary for estimating nutrient requirements. Many assumptions need to be made about the attributes of the population group. Furthermore, several factors (consumer behaviour as well as physiology) are to be included to characterize optimal health. b) Setting the nutrient recommendations: All available evidence is needed to formulate recommendations. Incorporating different endpoints provide the basis to formulate an optimal diet in terms of (non-)nutrients and food(group)s. c) Policy options: Policy options should be formulated on how the optimal diet can be achieved. They concern the advice of scientist and/or expert committees to the policy makers. Current policy options are setting up a task force, food based dietary guidelines, general health education, educational programme for specific group(s), voluntary or mandatory fortification, labelling, supplementation (general or for specific groups), inducing voluntary action in industry, legislation on micronutrient composition in food products, fiscal change, monitoring and evaluation of intake (via food consumption surveys) and/or nutritional status. d) Policy applications: Policies and planning, usually done by government, that lead to nutritional interventions or programmes. They usually require consideration of scientific, legal, regulatory, ethical and cultural issues, economic implications, and political and social priorities. This framework illustrates three dimensions of the process of setting (micro)nutrient requirements: 1) The logical sequence of scientific thinking from setting physiological requirements for nutritional health leading to evidence-based derivation of Nutrient Intake Values. 2) In the early stages nutritional and epidemiological science is the dominant source and in the later stages evidence from consumer and social sciences as well as stakeholder influences is used in deriving the options for changing the distribution of nutrient intakes. 3) The wider socio-political context: a feedback loop between health perception, actual health and food intake exists and is directly affected by the food industry and many other stakeholders. Moreover, from the viewpoint of policymakers, there are concerns for health promotion and disease prevention because of population health indices, costs of health care, and economic interests in the agro-food sector. In conclusion: A systematic approach for development and regular review of micronutrient requirements in Europe, transparently based on scientific evidence and best practices, enables national and international authorities/bodies to use the best available information obtained through evidence-based nutrition and accomplish well-considered food policy. Funded by an EU FP6 Network of Excellence (EURRECA, grant no. FP 6–036196-2). G. T. performed part of the work under a short-term contract for WHO Europe

    Performance of the LHCb vertex locator

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    The Vertex Locator (VELO) is a silicon microstrip detector that surrounds the proton-proton interaction region in the LHCb experiment. The performance of the detector during the first years of its physics operation is reviewed. The system is operated in vacuum, uses a bi-phase CO2 cooling system, and the sensors are moved to 7 mm from the LHC beam for physics data taking. The performance and stability of these characteristic features of the detector are described, and details of the material budget are given. The calibration of the timing and the data processing algorithms that are implemented in FPGAs are described. The system performance is fully characterised. The sensors have a signal to noise ratio of approximately 20 and a best hit resolution of 4 ÎŒm is achieved at the optimal track angle. The typical detector occupancy for minimum bias events in standard operating conditions in 2011 is around 0.5%, and the detector has less than 1% of faulty strips. The proximity of the detector to the beam means that the inner regions of the n+-on-n sensors have undergone space-charge sign inversion due to radiation damage. The VELO performance parameters that drive the experiment's physics sensitivity are also given. The track finding efficiency of the VELO is typically above 98% and the modules have been aligned to a precision of 1 ÎŒm for translations in the plane transverse to the beam. A primary vertex resolution of 13 ÎŒm in the transverse plane and 71 ÎŒm along the beam axis is achieved for vertices with 25 tracks. An impact parameter resolution of less than 35 ÎŒm is achieved for particles with transverse momentum greater than 1 GeV/c

    Precision luminosity measurements at LHCb

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    Measuring cross-sections at the LHC requires the luminosity to be determined accurately at each centre-of-mass energy √s. In this paper results are reported from the luminosity calibrations carried out at the LHC interaction point 8 with the LHCb detector for √s = 2.76, 7 and 8 TeV (proton-proton collisions) and for √sNN = 5 TeV (proton-lead collisions). Both the "van der Meer scan" and "beam-gas imaging" luminosity calibration methods were employed. It is observed that the beam density profile cannot always be described by a function that is factorizable in the two transverse coordinates. The introduction of a two-dimensional description of the beams improves significantly the consistency of the results. For proton-proton interactions at √s = 8 TeV a relative precision of the luminosity calibration of 1.47% is obtained using van der Meer scans and 1.43% using beam-gas imaging, resulting in a combined precision of 1.12%. Applying the calibration to the full data set determines the luminosity with a precision of 1.16%. This represents the most precise luminosity measurement achieved so far at a bunched-beam hadron collider

    Sensitivity Studies for Third-Generation Gravitational Wave Observatories

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    Advanced gravitational wave detectors, currently under construction, are expected to directly observe gravitational wave signals of astrophysical origin. The Einstein Telescope, a third-generation gravitational wave detector, has been proposed in order to fully open up the emerging field of gravitational wave astronomy. In this article we describe sensitivity models for the Einstein Telescope and investigate potential limits imposed by fundamental noise sources. A special focus is set on evaluating the frequency band below 10Hz where a complex mixture of seismic, gravity gradient, suspension thermal and radiation pressure noise dominates. We develop the most accurate sensitivity model, referred to as ET-D, for a third-generation detector so far, including the most relevant fundamental noise contributions.Comment: 13 pages, 7 picture

    Scientific Potential of Einstein Telescope

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    Einstein gravitational-wave Telescope (ET) is a design study funded by the European Commission to explore the technological challenges of and scientific benefits from building a third generation gravitational wave detector. The three-year study, which concluded earlier this year, has formulated the conceptual design of an observatory that can support the implementation of new technology for the next two to three decades. The goal of this talk is to introduce the audience to the overall aims and objectives of the project and to enumerate ET's potential to influence our understanding of fundamental physics, astrophysics and cosmology.Comment: Conforms to conference proceedings, several author names correcte
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