397 research outputs found

    Non-contrast CT markers of intracerebral hematoma expansion : a reliability study

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    Objectives: We evaluated whether clinicians agree in the detection of non-contrast CT markers of intracerebral hemorrhage (ICH) expansion. Methods: From our local dataset, we randomly sampled 60 patients diagnosed with spontaneous ICH. Fifteen physicians and trainees (Stroke Neurology, Interventional and Diagnostic Neuroradiology) were trained to identify six density (Barras density, black hole, blend, hypodensity, fluid level, swirl) and three shape (Barras shape, island, satellite) expansion markers, using standardized definitions. Thirteen raters performed a second assessment. Inter and intra-rater agreement were measured using Gwet’s AC1, with a coefficient > 0.60 indicating substantial to almost perfect agreement. Results: Almost perfect inter-rater agreement was observed for the swirl (0.85, 95% CI: 0.78-0.90) and fluid level (0.84, 95% CI: 0.76-0.90) markers, while the hypodensity (0.67, 95% CI: 0.56-0.76) and blend (0.62, 95% CI: 0.51-0.71) markers showed substantial agreement. Inter-rater agreement was otherwise moderate, and comparable between density and shape markers. Inter-rater agreement was lower for the three markers that require the rater to identify one specific axial slice (Barras density, Barras shape, island: 0.46, 95% CI: 0.40-0.52 versus others: 0.60, 95% CI: 0.56-0.63). Inter-observer agreement did not differ when stratified for raters’ experience, hematoma location, volume or anticoagulation status. Intrarater agreement was substantial to almost perfect for all but the black hole marker. Conclusion: In a large sample of raters with different backgrounds and expertise levels, only four of nine non-contrast CT markers of ICH expansion showed substantial to almost perfect inter-rater agreement

    The dependence of the anomalous J/psi suppression on the number of participant nucleons

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    The observation of an anomalous J/psi suppression in Pb-Pb collisions by the NA50 Collaboration can be considered as the most striking indication for the deconfinement of quarks and gluons at SPS energies. In this Letter, we determine the J/psi suppression pattern as a function of the forward hadronic energy E-ZDC measured in a Zero Degree Calorimeter (ZDC). The direct connection between EZDC and the geometry of the collision allows us to calculate, within a Glauber approach, the precise relation between the number of participant nucleons N-part and E-ZDC. Then, we check if the experimental data can be better explained by a sudden or a smooth onset of the anomalous J/psi suppression as a function of the number of participants. (C) 2001 Elsevier Science B.V. All rights reserved.info:eu-repo/semantics/publishedVersio

    Inclusive photon production at forward rapidities in proton-proton collisions at s\sqrt{s} = 0.9, 2.76 and 7 TeV

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    See paper for full list of authors – 24 pages, 10 captioned figures, 4 tables, authors from page 19, figures at http://aliceinfo.cern.ch/ArtSubmission/node/1024International audienceThe multiplicity and pseudorapidity distributions of inclusive photons have been measured at forward rapidities (2.3<η<3.92.3 < \eta < 3.9) in proton-proton collisions at three center-of-mass energies, s=0.9\sqrt{s}=0.9, 2.76 and 7 TeV using the ALICE detector. It is observed that the increase in the average photon multiplicity as a function of beam energy is compatible with both a logarithmic and a power-law dependence. The relative increase in average photon multiplicity produced in inelastic pp collisions at 2.76 and 7 TeV center-of-mass energies with respect to 0.9 TeV are 37.2% ±\pm 0.3% (stat) ±\pm 8.8% (sys) and 61.2% ±\pm 0.3% (stat) ±\pm 7.6% (sys), respectively. The photon multiplicity distributions for all center-of-mass energies are well described by negative binomial distributions. The multiplicity distributions are also presented in terms of KNO variables. The results are compared to model predictions, which are found in general to underestimate the data at large photon multiplicities, in particular at the highest center-of-mass energy. Limiting fragmentation behavior of photons has been explored with the data, but is not observed in the measured pseudorapidity range

    Transverse momentum distributions of J/ψ,ψJ/\psi,\psi', Drell-Yan and continuum dimuons produced in Pb-Pb interactions at the SPS

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    NA50Muon pairs produced in Pb-Pb interactions at 158~GeV/cc per nucleon are used to study the transverse momentum distributions of the \jpsi, \psip\ and dimuons in the mass continuum. In particular, the dependence of these distributions on the centrality of the Pb-Pb collision is investigated in detail

    Charmonium production in Pb-Pb collisions

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    NA50The elaboration of specific media-planning is necessary to communicate with an opinion leader. Opinion leaders in 27 product categories are selected from a 10,000 sample of French representative consumers. Magazine is the favorite media of opinion leaders; the more important is the number of product categories in which a consumer is leaders, the greater the media consumption. Leaders do not systematically prefer the Internet, their preference appears to be category specific. However, a second study conducted among 600 brand website visitors shows that brand sites represent a major information source for the leaders

    Evidence for deconfinement of quarks and gluons from the J/psiJ/psi suppression pattern measured in Pb-Pb collisions at the CERN-SPS

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    NA50The analysis of the data collected by the NA50 experiment in 1998, reported in this paper, extends and clarifies the pattern of thepreviously observed \jpsi\ anomalous suppression. This newmeasurement, besides providing a deeper understanding of the previousobservations, reveals a steady significative decrease in the \jpsi\ production rate up to the most central Pb-Pb collisions. It clearlyrules out the presently available conventional (hadronic) models of\jpsi\ suppression, which unanimously predict a saturation of the\jpsi\ rate for central Pb-Pb collisions. On the contrary andtogether with the sharp onset of the anomalous suppression previouslyreported, the new observation leads to a global production ratepattern which finds its natural explanation in the framework of theformation of a deconfined state of quarks and gluons

    Long-range angular correlations on the near and away side in p&#8211;Pb collisions at

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    Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions

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    We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe
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