The use of 4D-CTA in the diagnostic work-up of brain arteriovenous malformations

Neuro Imaging Researc

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

Measurement of charged-particle event shape variables in inclusive root(s)=7 TeV proton-proton interactions with the ATLAS detector

The measurement of charged-particle event shape variables is presented in inclusive inelastic pp collisions at a center-of-mass energy of 7 TeV using the ATLAS detector at the LHC. The observables studied are the transverse thrust, thrust minor, and transverse sphericity, each defined using the final-state charged particles' momentum components perpendicular to the beam direction. Events with at least six charged particles are selected by a minimum-bias trigger. In addition to the differential distributions, the evolution of each event shape variable as a function of the leading charged-particle transverse momentum, charged-particle multiplicity, and summed transverse momentum is presented. Predictions from several Monte Carlo models show significant deviations from data

Measurement of the production cross section for W-bosons in association with jets in pp collisions at √s=7 TeV with the ATLAS detector

This Letter reports on a first measurement of the inclusive W + jets cross section in proton–proton collisions at a centre-of-mass energy of 7 TeV at the LHC, with the ATLAS detector. Cross sections, in both the electron and muon decay modes of the W -boson, are presented as a function of jet multiplicity and of the transverse momentum of the leading and next-to-leading jets in the event. Measurements are also presented of the ratio of cross sections σ(W + n)/σ(W + n − 1) for inclusive jet multiplicities n = 1–4. The results, based on an integrated luminosity of 1.3 pb−1, have been corrected for all known detector effects and are quoted in a limited and well-defined range of jet and lepton kinematics. The measured cross sections are compared to particle-level predictions based on perturbative QCD. Next-toleading order calculations, studied here for n 2, are found in good agreement with the data. Leadingorder multiparton event generators, normalized to the NNLO total cross section, describe the data well for all measured jet multiplicities.

Anastomotic biliary strictures after liver transplantation:Causes and consequences

We retrospectively studied the prevalence, presentation, results of treatment, and graft and patient survival of grafts developing an anastomotic biliary stricture (AS) in 531 adult liver transplantations performed between 1979 and 2003. Clinical and laboratory information was obtained from the hospital files, and radiological studies were re-evaluated. Twenty-one possible risk factors for the development of AS (variables of donor, recipient, surgical procedure, and postoperative course) were analyzed in a univariate and stepwise multivariate model. Forty-seven grafts showed an anastomotic stricture: 42 in duct-to-duct anastomoses, and 5 in hepaticojejunal Roux-en-Y anastomoses. The cumulative risk of AS after 1, 5, and 10 years was 6.6%,10.6%, and 12.3% respectively. Postoperative bile leakage (P = 0.001), a female donor/male recipient combination (P = 0.010), and the era of transplantation (P = 0.006) were independent risk factors for the development of an AS. In 47% of cases, additional (radiologically minor) nonanastomotic strictures were diagnosed. All patients were successfully treated by 1 or more treatment modalities. As primary treatment, encloscopic retrograde cholangiopancreaticography (ERCP) was successful in 24 of 36 (67%) cases and percutaneous transhepatic cholangiodrainage in 4 of 11 (36%). In the end 15 patients (32%) were operated, all with long-term success. AS presenting more than 6 months after transplantation needed more episodes of stenting by ERCP, and more stents per episode compared to those presenting within 6 months and recurred more often. Graft and patient survival were not impaired by AS

First evidence of directed flow at 158 A GeV Pb+Pb collisions in WA98 experiment

The first evidence of directed flow at 158 A GeV Pb + Pb collisions is observed using the Plastic Ball detector in WA98 experiment. The azimuthal angle of the total transverse energy, Phi(o), is determined for each event using the observed protons in the Plastic Ball. A clear azimuthal asymmetry of fragments is observed with respect to Phi(o). The degree of azimuthal asymmetry is found to be largest in mid-central collisions, which is consistent with the picture of the collective flow. The p(t) spectra of particles measured in the mid-rapidity spectrometer has been studied in conjunction with the Plastic Ball, and different p(t) slopes with respect to Phi(o) for proton and pi(+) are observed

The LHC1 pixel detector studied in a 120 GeV/c pion test beam

Hybrid assemblies of LHC1 read-out chips and 300 mu m thick silicon pixel detectors have been tested with a 120 GeV/c pion beam at the CERN SPS. The equivalent noise charge at the input of the preamplifier is similar to 200 e(-). The particle detection efficiency is higher than 99.9%. A 30 ns wide efficiency plateau is reached for a 60 ns wide trigger pulse applied after a similar to 2 mu s delay. The 50 mu m x 50 mu m pixels yield a spatial precision of sigma = 129.4 +/- 0.2 mu m in the large pitch direction. In the other direction the precision is sigma = 12.2 +/- 0.2 mu m for single-pixel clusters and sigma = 8.2 +/- 0.2 mu m for double-pixel clusters, yielding an average of sigma = 11.4 +/- 0.2 mu m. Three different detector layouts on the same pitch were characterized. (C) 2000 Elsevier Science B.V. All rights reserved