890 resultados para West, Wilbur


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A search for exclusive or quasi-exclusive W+W- production by photon-photon interactions, pp → p(*)W +W-p(*), at √s=7 TeV is reported using data collected by the CMS detector with an integrated luminosity of 5.05 fb-1. Events are selected by requiring a μ ±e∓ vertex with no additional associated charged tracks and dilepton transverse momentum p T(μ ±e∓) > 30 GeV. Two events passing all selection requirements are observed in the data, compared to a standard model expectation of 2.2 ± 0.4 signal events with 0.84 ± 0.15 background. The tail of the dilepton p T distribution is studied for deviations from the standard model. No events are observed with p T > 100 GeV. Model-independent upper limits are computed and compared to predictions involving anomalous quartic gauge couplings. The limits on the parameters α0,C W/λ2 with a dipole form factor and an energy cutoff Λcutoff = 500 GeV are of the order of 10-4. © 2013 CERN for the benefit of the CMS collaboration.

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A measurement of the λb 0 lifetime using the decay λb 0-1, was recorded with the CMS experiment at the Large Hadron Collider using triggers that selected dimuon events in the J/ψ mass region. The λb 0 lifetime is measured to be 1.503 ± 0.052 (stat.) ± 0.031 (syst.) ps. [Figure not available: see fulltext.] © 2013 Cern for the benefit of the CMS collaboration.

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A search for microscopic black holes and string balls is presented, based on a data sample of pp collisions at √s=8 TeV recorded by the CMS experiment at the Large Hadron Collider and corresponding to an integrated luminosity of 12 fb-1. No excess of events with energetic multiparticle final states, typical of black hole production or of similar new physics processes, is observed. Given the agreement of the observations with the expected standard model background, which is dominated by QCD multijet production, 95% confidence level limits are set on the production of semiclassical or quantum black holes, or of string balls, corresponding to the exclusions of masses below 4.3 to 6.2 TeV, depending on model assumptions. In addition, model-independent limits are set on new physics processes resulting in energetic multiparticle final states. [Figure not available: see fulltext.] © 2013 CERN for the benefit of the CMS collaboration.

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Measurements are presented of the production of primary KS0 and Λ particles in proton-proton collisions at √s=7 TeV in the region transverse to the leading charged-particle jet in each event. The average multiplicity and average scalar transverse momentum sum of KS0 and Λ particles measured at pseudorapidities |η|<2 rise with increasing charged-particle jet pT in the range 1-10 GeV/c and saturate in the region 10-50 GeV/c. The rise and saturation of the strange-particle yields and transverse momentum sums in the underlying event are similar to those observed for inclusive charged particles, which confirms the impact-parameter picture of multiple parton interactions. The results are compared to recent tunes of the pythia Monte Carlo event generator. The pythia simulations underestimate the data by 15%-30% for KS0 mesons and by about 50% for Λ baryons, a deficit similar to that observed for the inclusive strange-particle production in non-single-diffractive proton-proton collisions. The constant strange- to charged-particle activity ratios with respect to the leading jet pT and similar trends for mesons and baryons indicate that the multiparton-interaction dynamics is decoupled from parton hadronization, which occurs at a later stage. © 2013 CERN, for the CMS Collaboration Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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Results are presented from a search for the rare decays Bs0→μ+μ- and B0→μ+μ - in pp collisions at √s=7 and 8 TeV, with data samples corresponding to integrated luminosities of 5 and 20 fb-1, respectively, collected by the CMS experiment at the LHC. An unbinned maximum-likelihood fit to the dimuon invariant mass distribution gives a branching fraction B(Bs0→μ+μ-)=(3.0-0.9+1.0) ×10-9, where the uncertainty includes both statistical and systematic contributions. An excess of Bs0→μ+μ- events with respect to background is observed with a significance of 4.3 standard deviations. For the decay B0→μ+μ- an upper limit of B(B0→μ+μ-)<1.1×10 -9 at the 95% confidence level is determined. Both results are in agreement with the expectations from the standard model. © 2013 CERN. Published by the American Physical Society under the terms of the.

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A search for supersymmetry is presented based on events with large missing transverse energy, no isolated electron or muon, and at least three jets with one or more identified as a bottom-quark jet. A simultaneous examination is performed of the numbers of events in exclusive bins of the scalar sum of jet transverse momentum values, missing transverse energy, and bottom-quark jet multiplicity. The sample, corresponding to an integrated luminosity of 19.4fb-1, consists of proton-proton collision data recorded at a center-of-mass energy of 8TeV with the CMS detector at the LHC in 2012. The observed numbers of events are found to be consistent with the standard model expectation, which is evaluated with control samples in data. The results are interpreted in the context of two simplified supersymmetric scenarios in which gluino pair production is followed by the decay of each gluino to an undetected lightest supersymmetric particle and either a bottom or top quark-antiquark pair, characteristic of gluino mediated bottom- or top-squark production. Using the production cross section calculated to next-to-leading-order plus next-to-leading-logarithm accuracy, and in the limit of a massless lightest supersymmetric particle, we exclude gluinos with masses below 1170GeV and 1020GeV for the two scenarios, respectively. © 2013 CERN.

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Biogeographical systems can be analyzed as networks of species and geographical units. Within such a biogeographical network, individual species may differ fundamentally in their linkage pattern, and therefore hold different topological roles. To advance our understanding of the relationship between species traits and large-scale species distribution patterns in archipelagos, we use a network approach to classify birds as one of four biogeographical species roles: peripherals, connectors, module hubs, and network hubs. These roles are based upon the position of species within the modular network of islands and species in Wallacea and the West Indies. We test whether species traits - including habitat requirements, altitudinal range-span, feeding guild, trophic level, and body length - correlate with species roles. In both archipelagos, habitat requirements, altitudinal range-span and body length show strong relations to species roles. In particular, species that occupy coastal- and open habitats, as well as habitat generalists, show higher proportions of connectors and network hubs and thus tend to span several biogeographical modules (i.e. subregions). Likewise, large body size and a wide altitudinal range-span are related to a wide distribution on many islands and across several biogeographical modules. On the other hand, species restricted to interior forest are mainly characterized as peripherals and, thus, have narrow and localized distributions within biogeographical modules rather than across the archipelago-wide network. These results suggest that the ecological amplitude of a species is highly related to its geographical distribution within and across bio geographical subregions and furthermore supports the idea that large-scale species distributions relate to distributions at the local community level. We finally discuss how our biogeographical species roles may correspond to the stages of the taxon cycle and other prominent theories of species assembly. © 2013 The Authors.

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Includes bibliography

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Se propone la creacion de un banco central regional para atender las necesidades fnancieras del grupo de paises que conforman los Estados Asociados de las Indias Occidentales.

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This issue of the FAL Bulletin examines the scale of maritime reefer trade in South America and the developments made in this area since the 1990s. It also looks at the increase in the capacity of liner services and the relationship between conventional and containerized reefer vessels in terms of trade volume, commodities exported and the destinations for exports from South America.

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BACKGROUND: Chronic leg ulcer may have an impact on patients' quality of life.OBJECTIVES:This study aimed to identify the impact of leg ulcers on patient's quality of life using the Dermatology Life Quality Index and to define the main factors correlated with this perception.METHOD:Cross-sectional, non-probabilistic sampling study. We included patients with chronic leg ulcers being treated for at least 3 months. A sociodemographic and clinical survey was conducted to assess the profile of the ulcers. We administered a screening for depressive symptoms and the Dermatology Life Quality Index. We performed a descriptive statistical analysis, chi-square test and Mann-Whitney test for categorical data, Pearson for numeric variables, and multiple regression for categorical data.RESULTS:Forty-one patients were assessed. Their mean age was 61.78 years. Venous ulcers (48.8%) were the most prevalent. Seventy-three percent of the sample perceived no impact/low impact on quality of life in the past week, and 26.8% perceived moderate/high impact. A multiple regression analysis identified the causes of lesion, pain related to the ulcers, time of onset, and severity of the depressive symptoms as the variables that had an influence on quality of life.CONCLUSIONS:The majority of the sample perceived low or no impact of the condition on the quality of the life. The variables etiology of the lesion (p<0.001), pain related to the ulcers (p=0.001), time of onset (p=0.006), and severity of the depressive symptoms (p<0.001) had an influence on the quality of life, suggesting the need for further studies with more robust designs to confirm the causal relationship between these characteristics and quality of life.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)