2,748 research outputs found

    Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

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    A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

    Combined search for the quarks of a sequential fourth generation

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    Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

    Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

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    The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

    A walking programme and a supervised exercise class versus usual physiotherapy for chronic low back pain: a single-blinded randomised controlled trial. (The Supervised Walking In comparison to Fitness Training for Back Pain (SWIFT) Trial)

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    BACKGROUND: Chronic low back pain (CLBP) is a persistent disabling condition with rising significant healthcare, social and economic costs. Current research supports the use of exercise-based treatment approaches that encourage people with CLBP to assume a physically active role in their recovery. While international clinical guidelines and systematic reviews for CLBP support supervised group exercise as an attractive first-line option for treating large numbers of CLBP patients at low cost, barriers to their delivery include space and time restrictions in healthcare settings and poor patient attendance. The European Clinical Guidelines have identified the need for research in the use of brief/minimal contact self-activation interventions that encourage participation in physical activity for CLBP. Walking may be an ideally suited form of individualized exercise prescription as it is easy to do, requires no special skills or facilities, and is achievable by virtually all ages with little risk of injury, but its effectiveness for LBP is unproven. METHODS AND DESIGN: This study will be an assessor-blinded randomized controlled trial that will investigate the difference in clinical effectiveness and costs of an individualized walking programme and a supervised general exercise programme compared to usual physiotherapy, which will act as the control group, in people with chronic low back pain. A sample of 246 patients will be recruited in Dublin, Ireland through acute general hospital outpatient physiotherapy departments that provide treatment for people with CLBP. Patients will be randomly allocated to one of the three groups in a concealed manner. The main outcomes will be functional disability, pain, quality of life, fear avoidance, back beliefs, physical activity, satisfaction and costs, which will be evaluated at baseline, and 3, 6 and 12 months [follow-up by pre-paid postage]. Qualitative telephone interviews and focus groups will be embedded in the research design to obtain feedback about participants' experiences of the interventions and trial participation, and to inform interpretation of the quantitative data. Planned analysis will be by intention to treat (quantitative data) and thematic analysis (qualitative data) DISCUSSION: The trial will evaluate the effectiveness of a walking programme and a supervised general exercise programme compared to usual physiotherapy in people with CLBP. TRIAL REGISTRATION: Current controlled trial ISRCTN1759209

    Effect of acute pesticide exposure on bee spatial working memory using an analogue of the radial-arm maze

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    Pesticides, including neonicotinoids, typically target pest insects by being neurotoxic. Inadvertent exposure to foraging insect pollinators is usually sub-lethal, but may affect cognition. One cognitive trait, spatial working memory, may be important in avoiding previously-visited flowers and other spatial tasks such as navigation. To test this, we investigated the effect of acute thiamethoxam exposure on spatial working memory in the bumblebee Bombus terrestris, using an adaptation of the radial-arm maze (RAM). We first demonstrated that bumblebees use spatial working memory to solve the RAM by showing that untreated bees performed significantly better than would be expected if choices were random or governed by stereotyped visitation rules. We then exposed bees to either a high sub-lethal positive control thiamethoxam dose (2.5ng-1 bee), or one of two low doses (0.377 or 0.091ng-1) based on estimated field-realistic exposure. The high dose caused bees to make more and earlier spatial memory errors and take longer to complete the task than unexposed bees. For the low doses, the negative effects were smaller but statistically significant, and dependent on bee size. The spatial working memory impairment shown here has the potential to harm bees exposed to thiamethoxam, through possible impacts on foraging efficiency or homing

    Search for light bosons in decays of the 125 GeV Higgs boson in proton-proton collisions at root s=8 TeV

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    Study of hadronic event-shape variables in multijet final states in pp collisions at √s=7 TeV

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    Historicising Material Agency: from Relations to Relational Constellations

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    Relational approaches have gradually been changing the face of archaeology over the last decade: analytically, through formal network analysis; and interpretively, with various frameworks of human-thing relations. Their popularity has been such, however, that it threatens to undermine their relevance. If everyone agrees that we should understand past worlds by tracing relations, then ‘finding relations’ in the past becomes a self-fulfilling prophecy. Focusing primarily on the interpretive approaches of material culture studies, this article proposes to counter the threat of irrelevance by not just tracing human-thing relations, but characterising how sets of relations were ordered. Such ordered sets are termed ‘relational constellations’. The article describes three relational constellations and their consequences based on practices of fine ware production in the Western Roman provinces (first century BC – third century AD): the fluid, the categorical, and the rooted constellation. Specifying relational constellations allows reconnecting material culture to specific historical trajectories, and offers scope for meaningful cross-cultural comparisons. As such a small theoretical addition based on the existing toolbox of practice-based approaches and relational thought can impact on historical narratives, and can save relational frameworks from the danger of triviality.This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/s10816-015-9244-
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