1,727 research outputs found

    Nuevos registros de Amphisbaena fuliginosa Linnaeus, 1758 (Squamata: Amphisbaenidae) para la Amazonia Boliviana y primer registro para el departamento del Beni

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    Los especímenes de Amphisbaena fuliginosa representan un aporte importante para el mejor conocimiento sobre la distribución de la especie en Bolivia. Sin embargo, comparando los caracteres merísticos de los tres especímenes del presente estudio con los descritos por Vanzolini (2002a) para las diferentes subespecies de A. fuliginosa, resulta que dos de estas (CIRAH-951, 1000) coinciden con A. fuliginosa bassleri y una (CIRAH-1001) con A. fuliginosa wiedi (excepto en los anillos de la cola) y no así con el patrón de color descritos por este autor. Además, constituyen los primeros registros para el departamento del Beni (Riberalta), ciudad ubicada a orillas del río Beni en la Amazonia boliviana y una de las regiones escasamente estudiadas, pero altamente diversa.Asociación Herpetológica Argentin

    Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb−1 of s√=7TeV proton-proton collisions

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    Results are presented of a search for new particles decaying to large numbers of jets in association with missing transverse momentum, using 4.7 fb−1 of pp collision data at s√=7TeV collected by the ATLAS experiment at the Large Hadron Collider in 2011. The event selection requires missing transverse momentum, no isolated electrons or muons, and from ≥6 to ≥9 jets. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of a MSUGRA/CMSSM supersymmetric model, where, for large universal scalar mass m 0, gluino masses smaller than 840 GeV are excluded at the 95% confidence level, extending previously published limits. Within a simplified model containing only a gluino octet and a neutralino, gluino masses smaller than 870 GeV are similarly excluded for neutralino masses below 100 GeV

    Standalone vertex finding in the ATLAS muon spectrometer

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    A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

    Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

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    Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

    Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

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    A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction

    Measurement of the top quark-pair production cross section with ATLAS in pp collisions at \sqrt{s}=7\TeV

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    A measurement of the production cross-section for top quark pairs(\ttbar) in pppp collisions at \sqrt{s}=7 \TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron ee or muon μ\mu) with large missing transverse energy and at least four jets, and dilepton (eeee, μμ\mu\mu or eμe\mu) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-\ttbar Standard Model processes are estimated using data-driven methods and determined to be 12.2±3.912.2 \pm 3.9 events and 2.5±0.62.5 \pm 0.6 events, respectively. The kinematic properties of the selected events are consistent with SM \ttbar production. The inclusive top quark pair production cross-section is measured to be \sigmattbar=145 \pm 31 ^{+42}_{-27} pb where the first uncertainty is statistical and the second systematic. The measurement agrees with perturbative QCD calculations.Comment: 30 pages plus author list (50 pages total), 9 figures, 11 tables, CERN-PH number and final journal adde

    Inclusive search for same-sign dilepton signatures in pp collisions at root s=7 TeV with the ATLAS detector

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    An inclusive search is presented for new physics in events with two isolated leptons (e or mu) having the same electric charge. The data are selected from events collected from p p collisions at root s = 7 TeV by the ATLAS detector and correspond to an integrated luminosity of 34 pb(-1). The spectra in dilepton invariant mass, missing transverse momentum and jet multiplicity are presented and compared to Standard Model predictions. In this event sample, no evidence is found for contributions beyond those of the Standard Model. Limits are set on the cross-section in a fiducial region for new sources of same-sign high-mass dilepton events in the ee, e mu and mu mu channels. Four models predicting same-sign dilepton signals are constrained: two descriptions of Majorana neutrinos, a cascade topology similar to supersymmetry or universal extra dimensions, and fourth generation d-type quarks. Assuming a new physics scale of 1 TeV, Majorana neutrinos produced by an effective operator V with masses below 460 GeV are excluded at 95% confidence level. A lower limit of 290 GeV is set at 95% confidence level on the mass of fourth generation d-type quarks

    Participation in daily life activities at two months after stroke predicts long-term health-related quality of life

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    Background: After stroke, many patients experience problems with participation in daily activities. Improving participation is the main goal in stroke rehabilitation. However, the longitudinal relationship between participation and health-related quality of life (HRQoL) remains unclear. Objectives: This study aimed to examine (1) the predictive value of participation at two months on long-term HRQoL and (2) the longitudinal relationship between participation and HRQoL. Methods: In this multicenter, prospective cohort study, patients were assessed at two and 12 months after stroke. Participation was measured with the Restriction subscale of the Utrecht Scale for Evaluation of Rehabilitation–Participation. HRQoL was assessed with the three-level version of the EuroQoL five dimensions questionnaire index score. Results: This study included 291 patients. Mean age was 66.6 ± 12.4 years, 64.3% were male and mean National Institutes of Health Stroke Scale (NIHSS) was 2.5 ± 2.9. Multivariable linear regression, adjusted for demographic characteristics, stroke characteristics, physical and cognitive impairment, showed that a higher level of participation at two months correlated with a higher HRQoL at one year (B =.004; 95% CI =.002–.005). Patients whose participation improved had a greater increase in HRQoL, compared to patients without improvement (0.080 ±.21 versus −.054 ±.21; p &lt;.001). Conclusions: The level of participation at two months post-stroke predicts HRQoL at one year. Improvement in participation during the first year after stroke is associated with improvement in HRQoL. We recommend including the assessment of participation in daily activities at follow-up visits.</p

    Measurement of inclusive two-particle angular correlations in pp collisions with the ATLAS detector at the LHC