48 research outputs found

    Extended Lower Limb Venous Ultrasound for the Diagnosis of Proximal and Distal Vein Thrombosis in Asymptomatic Patients after Total Hip Replacement

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    AbstractObjective. To assess the performance of extended lower limb venous ultrasound (US) for the diagnosis of asymptomatic deep vein thrombosis (DVT) and to estimate a 3-month DVT incidence on repeated US after total hip replacement.Design. Diagnostic performance study and prospective cohort study.Materials and methods. US was compared to phlebography in 70 consecutive patients and interobserver agreement was assessed in the last 48 patients at day 8. US was repeated in these 48 patients at day 13 and day 90.Results. Phlebography demonstrated a DVT in 18/70 (26%) patients, with five proximal and 13 distal and US in 23/70 (33%) patients, with eight proximal and 15 distal. Sensitivity and specificity of US with 95% CI were 94% (73–100) and 89% (76–96), respectively. Sensitivity in isolated distal vein thrombosis was 92% (67–99). The Kappa coefficient for agreement between observers was 0.84 (0.66–1.00). Follow-up showed a DVT in 15/48 (31%) patients on day 8, in 20/48 patients (42%) on day 13. DVT recurred in two patients during follow-up.Conclusions. The incidence of asymptomatic DVT is still significant despite prophylaxis but most DVTs remain distal and occur in the first 2 weeks. Extended US could replace phlebography for systematic screening in clinical trials using surrogate endpoints in view of its high accuracy and reliability

    The AllDifferent Constraint with Precedences

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    We propose ALLDIFFPREC, a new global constraint that combines together an ALLDIFFERENT constraint with precedence constraints that strictly order given pairs of variables. We identify a number of applications for this global constraint including instruction scheduling and symmetry breaking. We give an efficient propagation algorithm that enforces bounds consistency on this global constraint. We show how to implement this propagator using a decomposition that extends the bounds consistency enforcing decomposition proposed for the ALLDIFFERENT constraint. Finally, we prove that enforcing domain consistency on this global constraint is NP-hard in general

    SimProp: a Simulation Code for Ultra High Energy Cosmic Ray Propagation

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    A new Monte Carlo simulation code for the propagation of Ultra High Energy Cosmic Rays is presented. The results of this simulation scheme are tested by comparison with results of another Monte Carlo computation as well as with the results obtained by directly solving the kinetic equation for the propagation of Ultra High Energy Cosmic Rays. A short comparison with the latest flux published by the Pierre Auger collaboration is also presented.Comment: 19 pages, 12 eps figures, version accepted for publication in JCA

    Extragalactic Sources for Ultra High Energy Cosmic Ray Nuclei

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    In this article we examine the hypothesis that the highest energy cosmic rays are complex nuclei from extragalactic sources. Under reasonable physical assumptions, we show that the nearby metally rich starburst galaxies (M82 and NGC 253) can produce all the events observed above the ankle. This requires diffusion of particles below 102010^{20} eV in extragalactic magnetic fields B15B \approx 15 nG. Above 101910^{19} eV, the model predicts the presence of significant fluxes of medium mass and heavy nuclei with small rate of change of composition. Notwithstanding, the most salient feature of the starburst-hypothesis is a slight anisotropy induced by iron debris just before the spectrum-cutoff.Comment: To appear in Phys. Rev. D, reference adde

    Nearby quasar remnants and ultra-high energy cosmic rays

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    As recently suggested, nearby quasar remnants are plausible sites of black-hole based compact dynamos that could be capable of accelerating ultra-high energy cosmic rays (UHECRs). In such a model, UHECRs would originate at the nuclei of nearby dead quasars, those in which the putative underlying supermassive black holes are suitably spun-up. Based on galactic optical luminosity, morphological type, and redshift, we have compiled a small sample of nearby objects selected to be highly luminous, bulge-dominated galaxies, likely quasar remnants. The sky coordinates of these galaxies were then correlated with the arrival directions of cosmic rays detected at energies >40> 40 EeV. An apparently significant correlation appears in our data. This correlation appears at closer angular scales than those expected when taking into account the deflection caused by typically assumed IGM or galactic magnetic fields over a charged particle trajectory. Possible scenarios producing this effect are discussed, as is the astrophysics of the quasar remnant candidates. We suggest that quasar remnants be also taken into account in the forthcoming detailed search for correlations using data from the Auger Observatory.Comment: 2 figures, 4 tables, 11 pages. Final version to appear in Physical Review

    Early psychological care of the French victims of the Costa Concordia shipwreck

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    Most of the French passengers who survived the shipwreck of the cruise ship Costa Concordia were repatriatedfrom Italy to Marseille, one of the stopovers of the cruise. The shipwreck happened during the nightof 13th–14th January 2012 and entailed the forced evacuation of 4195 passengers and crewmembers.Thirty-two persons died and 2 others are still reported missing. The massive and unexpected inflow of402 French citizens in the port of Marseille required the quick setting up of welcome facilities, not only tosolve logistical problems, but also to address psychological and sometimes even medical problems. ThePrehospital Psychological Emergency Service (CUMP) and the Prehospital Emergency Medical Service(SAMU) of Marseille examined 196 persons in total, and were able to avoid a great number of emergencyadmissions deemed necessary because of difficult psychological situations (death, missing or lost persons,acute stress). The objective of this report is to rapidly present the emergency committee as a whole andto describe in more detail the work that the CUMP accomplished during the 36 hours necessary to takecharge of the majority of the French passengers of the Costa Concordia.Most of the French passengers who survived the shipwreck of the cruise ship Costa Concordia were repatriatedfrom Italy to Marseille, one of the stopovers of the cruise. The shipwreck happened during the nightof 13th–14th January 2012 and entailed the forced evacuation of 4195 passengers and crewmembers.Thirty-two persons died and 2 others are still reported missing. The massive and unexpected inflow of402 French citizens in the port of Marseille required the quick setting up of welcome facilities, not only tosolve logistical problems, but also to address psychological and sometimes even medical problems. ThePrehospital Psychological Emergency Service (CUMP) and the Prehospital Emergency Medical Service(SAMU) of Marseille examined 196 persons in total, and were able to avoid a great number of emergencyadmissions deemed necessary because of difficult psychological situations (death, missing or lost persons,acute stress). The objective of this report is to rapidly present the emergency committee as a whole andto describe in more detail the work that the CUMP accomplished during the 36 hours necessary to takecharge of the majority of the French passengers of the Costa Concordia

    RAYONS GAMMA D'ORIGINE EXTRAGALACTIQUE

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    L'étude de l'opacité de l'univers au rayonnement électromagnétique énergétique (hν > 1 eV) montre que les photons ayant entre 1 MeV et quelques GeV peuvent avoir été produits dans des phases prégalactiques de l'évolution de l'univers correspondant à des décalages cosmologiques vers le rouge de 100 ou plus. Le seul rayonnement gamma dont l'origine extragalactique soit bien établie est le fond diffus isotrope observé entre quelques MeV et 150 MeV et constitue une des données fondamentales de la cosmologie physique. Le spectre de ce rayonnement isotrope semble montrer l'existence d'une composante d'origine différente de celle observée en dessous de 1 MeV. Néanmoins les mesures les plus critiques appartiennent à la région 1 à 30 MeV où les raies nucléaires induites dans les détecteurs par les rayons cosmiques rendent l'interprétation des résultats expérimentaux très difficile et ce point reste très controversé. Les mécanismes physiques pouvant contribuer à ce fond diffus sont : — l'interaction des électrons cosmiques extragalactiques avec le rayonnement, — l'interaction des électrons cosmiques extragalactiques avec la matière, - l'interaction des protons cosmiques avec la matière intergalactique, — l'annihilation matière antimatière. De plus une partie ou même la totalité de ce flux peut être la somme de sources lointaines (galaxies actives, quasars...). Aucune source extragalactique de rayonnement gamma n'a été confirmée jusqu'à maintenant. Des prédictions théoriques existent pour certains modèles de noyaux de galaxies et de quasars. Certains des modèles proposés pour interpréter les sursauts gamma observés au cours des deux dernières années font appel à une origine extragalactique
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