1,597 research outputs found

    Study of elementary reactions with the HADES dielectron spectrometer

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    Results obtained with the HADES dielectron spectrometer at GSI are discussed, with emphasis on dilepton production in elementary reactions.Comment: invited talk at the Mazurian Lakes Conference on Physics, Piaski, Poland, August 30 - September 6, 2009, to appear in the proceedings (Acta Polonica

    Dipion and dielectron production in quasi-free np reactions with HADES

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    Les interventions publiques nationales en matière d'abus de substances et de dépendances : une revue internationale

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    [Table des matières] Résumé. Zusammenfassung. 1. Situation de départ et mandat. 2. Problématique. 3. Questions de recherche. 4. Méthode. 5. Résultats généraux. 6. Résultats détaillés : évolution des modèles des interventions publiques en matière de dépendances. 7. Résultats détaillés : évolution des mesures en matière de dépendances. 8. Conclusions et leçons à tirer. 9. Annexes - fiches des pays : Europe, Allemagne, Autriche, Belgique, Danemark, Espagne, Finlande, France, Grèce, Irlande, Italie, Luxembourg, Norvège, Pays-Bas, Portugal, Royaume-Uni (Angleterre, Pays de Galles, Ecosse, Irlande du Nord), Suède, Australie, Canada, Etats-Unis

    On Evaluation of a Population of Bayesian Networks

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    Two new evaluation of quality approaches for a population of Bayesian networks (BN) are proposed in this paper. The first approach relies on the use of statistical principle with application of well-known evaluation methods. The other bases on quasi essential graph (QEG), an extension of essential graph (EG), that is a presentative graph for all BN of the population. In QEG, each edge is statistically weighted in two parts: (1) undirected part that represents the power of the relationship; (2) arrow part that represents the reliability of the orientation. Results of application to the both simulated and real-world problems show that these proposed approaches are the others helpful solutions for the problem of edge orientation and for the visualization of results of evaluation methods

    Modelling the mid-Pliocene Warm Period climate with the IPSL coupled model and its atmospheric component LMDZ5A

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    This paper describes the experimental design and model results of the climate simulations of the mid-Pliocene Warm Period (mPWP, ca. 3.3–3 Ma) using the Institut Pierre Simon Laplace model (IPSLCM5A), in the framework of the Pliocene Model Intercomparison Project (PlioMIP). We use the IPSL atmosphere ocean general circulation model (AOGCM), and its atmospheric component alone (AGCM), to simulate the climate of the mPWP. Boundary conditions such as sea surface temperatures (SSTs), topography, ice-sheet extent and vegetation are derived from the ones imposed by the Pliocene Model Intercomparison Project (PlioMIP), described in Haywood et al. (2010, 2011). We first describe the IPSL model main features, and then give a full description of the boundary conditions used for atmospheric model and coupled model experiments. The climatic outputs of the mPWP simulations are detailed and compared to the corresponding control simulations. The simulated warming relative to the control simulation is 1.94 °C in the atmospheric and 2.07 °C in the coupled model experiments. In both experiments, warming is larger at high latitudes. Mechanisms governing the simulated precipitation patterns are different in the coupled model than in the atmospheric model alone, because of the reduced gradients in imposed SSTs, which impacts the Hadley and Walker circulations. In addition, a sensitivity test to the change of land-sea mask in the atmospheric model, representing a sea-level change from present-day to 25 m higher during the mid-Pliocene, is described. We find that surface temperature differences can be large (several degrees Celsius) but are restricted to the areas that were changed from ocean to land or vice versa. In terms of precipitation, impact on polar regions is minor although the change in land-sea mask is significant in these areas

    In-medium effects on K-0 mesons in relativistic heavy-ion collisions

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    We present the transverse momentum spectra and rapidity distributions of pi(-) and K-S(0) in Ar + KCl reactions at a beam kinetic energy of 1.756 A GeV measured with the High Acceptance Di-Electron Spectrometer (HADES). The reconstructed K-S(0) sample is characterized by good event statistics for a wide range in momentum and rapidity. We compare the experimental pi(-) and K-S(0) distributions to predictions by the Isospin Quantum Molecular Dynamics (IQMD) model. The model calculations show that K-S(0) at low transverse momenta constitute a particularly well-suited tool to investigate the kaon in-medium potential. Our K-S(0) data suggest a strong repulsive in-medium K-0 potential of about 40 MeV strength.We gratefully acknowledge the useful discussions with J. Aichelin and H. Oeschler. The HADES collaboration gratefully acknowledges the support by BMBF grants 06TM970I, 06GI146I, 06FY171, and 06DR135 (Germany), by GSI (TMFR1, GI/ME3, OF/STR), by Excellence Cluster of Universe (Germany), by grants GA AS CR IAA100480803 and MSMT LC 07050 (Czech Republic), by grant KBN 5P03B 140 20 (Poland), by INFN (Italy), by CNRS/IN2P3 (France), by grants MCYT FPA2000-2041-C02-02 and XUGA PGID T02PXIC20605PN (Spain), by grant UCY-10.3.11.12 (Cyprus), by INTAS grant 06-1000012-8861 and EU contract RII3-CT-2004-506078.Peer reviewe

    Pluto: A Monte Carlo Simulation Tool for Hadronic Physics

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    Pluto is a Monte-Carlo event generator designed for hadronic interactions from Pion production threshold to intermediate energies of a few GeV per nucleon, as well as for studies of heavy ion reactions. This report gives an overview of the design of the package, the included models and the user interface.Comment: XI International Workshop on Advanced Computing and Analysis Techniques in Physics Research, April 23-27 2007, Amsterdam, the Netherland

    Web-based multimodal graphs for visually impaired people

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    This paper describes the development and evaluation of Web-based multimodal graphs designed for visually impaired and blind people. The information in the graphs is conveyed to visually impaired people through haptic and audio channels. The motivation of this work is to address problems faced by visually impaired people in accessing graphical information on the Internet, particularly the common types of graphs for data visualization. In our work, line graphs, bar charts and pie charts are accessible through a force feedback device, the Logitech WingMan Force Feedback Mouse. Pre-recorded sound files are used to represent graph contents to users. In order to test the usability of the developed Web graphs, an evaluation was conducted with bar charts as the experimental platform. The results showed that the participants could successfully use the haptic and audio features to extract information from the Web graphs

    Optimization of the HADES secondary pion beam spectrometer

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