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
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
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
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
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 eV in extragalactic magnetic fields nG. Above 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
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 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
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
Constraining the wind launching region in Herbig Ae stars: AMBER/VLTI spectroscopy of HD 104237
Astronomy and Astrophysics, 464, pp. 55-58, http://dx.doi.org./10.1051/0004-6361:20065719International audienc
RAYONS GAMMA D'ORIGINE EXTRAGALACTIQUE
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