1,254 research outputs found

    Production of Strange Clusters and Strange Matter in Nucleus-Nucleus Collisions at the AGS

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    Production probabilities for strange clusters and strange matter in Au+Au collisions at AGS energy are obtained in the thermal fireball model. The only parameters of the model, the baryon chemical potential and temperature, were determined from a description of the rather complete set of hadron yields from Si+nucleus collisions at the AGS. For the production of light nuclear fragments and strange clusters the results are similar to recent coalescence model calculations. Strange matter production with baryon number larger than 10 is predicted to be much smaller than any current experimental sensitivities.Comment: 9 Pages (no figures

    Missed Opportunities: Evolution of Patients Leaving without Being Seen or against Medical Advice during a Six-Year Period in a Swiss Tertiary Hospital Emergency Department.

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    Aim. The study aimed at describing the evolution over a 6-year period of patients leaving the emergency department (ED) before being seen ("left without being seen" or LWBS) or against medical advice ("left against medical advice" or LAMA) and at describing their characteristics. Methods. A retrospective database analysis of all adult patients who are admitted to the ED, between 2005 and 2010, and who left before being evaluated or against medical advice, in a tertiary university hospital. Results. During the study period, among the 307,716 patients who were registered in the ED, 1,157 LWBS (0.4%) and 1,853 LAMA (0.9%) patients were identified. These proportions remained stable over the period. The patients had an average age of 38.5 ± 15.9 years for LWBS and 41.9 ± 17.4 years for LAMA. The median time spent in the ED before leaving was 102.4 minutes for the LWBS patients and 226 minutes for LAMA patients. The most frequent reason for LAMA was related to the excessive length of stay. Conclusion. The rates of LWBS and LAMA patients were low and remained stable. The patients shared similar characteristics and reasons for leaving were largely related to the length of stay or waiting time

    Open Charm Enhancement in Pb+Pb Collisions at SPS

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    The statistical coalescence model for the production of open and hidden charm is considered within the canonical ensemble formulation. The data for the J/\psi multiplicity in Pb+Pb collisions at 158 A GeV are used for the model prediction of the open charm yield. We find a strong enhancement of the open charm production, by a factor of about 2--4, over the standard hard-collision model extrapolation from nucleon-nucleon to nucleus-nucleus collisions. A possible mechanism of the open charm enhancement in A+A collisions at the SPS energies is proposed.Comment: 4 pages, Late

    L’Indice de biodiversité potentielle (IBP) en région méditerranéenne

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    L’IBP est un outil pour évaluer la biodiversité taxonomique ordinaire des peuplements forestiers. Rapide et simple à utiliser, il est basé sur l’estimation indirecte de la biodiversité au travers de l’évaluation de la capacité d’accueil en espèces et en communautés, à l’échelle du peuplement forestier. Il consiste à apprécier un ensemble de dix facteurs parmi ceux qui sont habituellement reconnus comme les plus favorables à la diversité interne des peuplements. Un score de 0, 2 ou 5 est donné sur le terrain à chacun des facteurs selon une échelle de valeurs seuils et leur somme donne l’IBP. L’IBP est adapté à toutes les forêts des domaines atlantique et continental. L’extension à la région méditerranéenne est à l’étude depuis 2009. Le domaine d’utilisation de l’IBP « méditerranée » a été précisé, tant au niveau géographique qu’au niveau des formations végétales concernées. Les facteurs et les seuils ont été revus pour tenir compte des caractéristiques des forêts méditerranéennes. La problématique des incendies est également étudiée à travers les relations entre la biodiversité taxonomique et les feux de forêt, car la forêt méditerranéenne est particulièrement concernée

    Open and Hidden Charm Production in Heavy Ion Collisions at Ultrarelativistic Energies

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    We consider the production of the open charm and J/psi mesons in heavy ion collisions at BNL RHIC. We discuss several recently developed pictures for J/psi production and argue that a measurement at RHIC energies is crucial for disentangling these different descriptions.Comment: 19 pages, Latex, 5 PS-figures. v3: Fig.6 is adde

    Charmonium Suppression by Comover Scattering in Pb+Pb Collisions

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    The first reports of ψ\psi and ψ\psi' production from experiment NA50 at the CERN SPS are compared to predictions based on a hadronic model of charmonium suppression. Data on centrality dependence and total cross sections are in good accord with these predictions.Comment: 9 pages, latex, 6 figures, epsf, figure added and text modified to clarify result

    The High E_T Drop of J/psi to Drell-Yan Ratio from the Statistical c anti-c Coalescence Model

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    The dependence of the J/psi yield on the transverse energy E_T in heavy ion collisions is considered within the statistical c anti-c coalescence model. The model fits the NA50 data for Pb+Pb collisions at the CERN SPS even in the high-E_T region (E_T > 100 GeV). Here E_T-fluctuations and E_T-losses in the dimuon event sample naturally create the celebrated drop in the J/psi to Drell-Yan ratio.Comment: 14 pages, REVTeX, 1 PS-figure. v2: References are corrected and update

    Millikelvin measurements of permittivity and loss tangent of lithium niobate

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    Lithium Niobate is an electro-optic material with many applications in microwave signal processing, communication, quantum sensing, and quantum computing. In this letter, we present findings on evaluating the complex electromagnetic permittivity of lithium niobate at millikelvin temperatures. Measurements are carried out using a resonant-type method with a superconducting radio-frequency (SRF) cavity operating at 7 GHz and designed to characterize anisotropic dielectrics. The relative permittivity tensor and loss tangent are measured at 50 mK with unprecedented accuracy.Comment: 5 pages, 4 figure

    Direct observation of homogeneous cavitation in nanopores

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    We report on the evaporation of hexane from porous alumina and silicon membranes. These membranes contain billions of independent nanopores tailored to an ink-bottle shape, where a cavity several tens of nanometers in diameter is separated from the bulk vapor by a constriction. For alumina membranes with narrow enough constrictions, we demonstrate that cavity evaporation proceeds by cavitation. Measurements of the pressure dependence of the cavitation rate follow the predictions of the bulk, homogeneous, classical nucleation theory, definitively establishing the relevance of homogeneous cavitation as an evaporation mechanism in mesoporous materials. Our results imply that porous alumina membranes are a promising new system to study liquids in a deeply metastable state.Comment: 14 pages , 4 figures. Source files also contain Supplemental Material (Doebele_HomogeneousCavitationMembranes_SM.pdf
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