81 research outputs found

    A Community-Based Study of Factors Associated with Continuing Transmission of Lymphatic Filariasis in Leogane, Haiti

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    Seven rounds of mass drug administration (MDA) have been administered in Leogane, Haiti, an area hyperendemic for lymphatic filariasis (LF). Sentinel site surveys showed that the prevalence of microfilaremia was reduced to <1% from levels as high as 15.5%, suggesting that transmission had been reduced. A separate 30-cluster survey of 2- to 4-year-old children was conducted to determine if MDA interrupted transmission. Antigen and antifilarial antibody prevalence were 14.3% and 19.7%, respectively. Follow-up surveys were done in 6 villages, including those selected for the cluster survey, to assess risk factors related to continued LF transmission and to pinpoint hotspots of transmission. One hundred houses were mapped in each village using GPS-enabled PDAs, and then 30 houses and 10 alternates were chosen for testing. All individuals in selected houses were asked to participate in a short survey about participation in MDA, history of residence in Leogane and general knowledge of LF. Survey teams returned to the houses at night to collect blood for antigen testing, microfilaremia and Bm14 antibody testing and collected mosquitoes from these communities in parallel. Antigen prevalence was highly variable among the 6 villages, with the highest being 38.2% (Dampus) and the lowest being 2.9% (Corail Lemaire); overall antigen prevalence was 18.5%. Initial cluster surveys of 2- to 4-year-old children were not related to community antigen prevalence. Nearest neighbor analysis found evidence of clustering of infection suggesting that LF infection was focal in distribution. Antigen prevalence among individuals who were systematically noncompliant with the MDAs, i.e. they had never participated, was significantly higher than among compliant individuals (p<0.05). A logistic regression model found that of the factors examined for association with infection, only noncompliance was significantly associated with infection. Thus, continuing transmission of LF seems to be linked to rates of systematic noncompliance

    Bushfire in Madagascar: natural hazard, useful tool, and change agent

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    Bushfire does not usually figure on lists of natural hazards in Madagascar, despite being damaging hazard on the island. This chapter argues that the lack of attention to fire comes from the fact that fire is multivalent, ambiguous, and flexible, being simultaneously an occasional 'hazard' for thatch-roof huts or crop fields, a 'useful tool' that farmers and pastoralists use to manage vegetation, and a major transformational force, or 'change agent', that damages land and forest. The chapter builds on the concept of pyric phases, identifying six important pyric phases in which fire serves, or is perceived to serve, different roles as hazard, tool, or change agent

    Lawson criterion for ignition exceeded in an inertial fusion experiment

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    For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

    Search for flavor changing neutral currents in top quark decays in pp collisions at 7 TeV

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    The results of a search for flavor changing neutral currents in top quark decays t -> Zq in events with a topology compatible with the decay chain t (t) over bar -> Wb + Zq -> lvb + llq are presented. The search is performed with a data sample corresponding to an integrated luminosity of 5.0 fb(-1) of proton-proton collisions at a center-of-mass energy of 7 TeV, collected with the CMS detector at the LHC. The observed number of events agrees with the standard model prediction and no evidence for flavor changing neutral currents in top quark decays is found. A t -> Zq branching fraction greater than 0.21% is excluded at the 95% confidence level. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved

    Search for supersymmetry in final states with missing transverse energy and 0, 1, 2, or >= 3 b-quark jets in 7 TeV pp collisions using the variable alpha(T)

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    A search for supersymmetry in final states with jets and missing transverse energy is performed in pp collisions at a centre-of-mass energy of root s = 7 TeV. The data sample corresponds to an integrated luminosity of 4.98 fb(-1) collected by the CMS experiment at the LHC. In this search, a dimensionless kinematic variable, alpha(T), is used as the main discriminator between events with genuine and misreconstructed missing transverse energy. The search is performed in a signal region that is binned in the scalar sum of the transverse energy of jets and the number of jets identified as originating from a bottom quark. No excess of events over the standard model expectation is found. Exclusion limits are set in the parameter space of the constrained minimal supersymmetric extension of the standard model, and also in simplified models, with a special emphasis on compressed spectra and third-generation scenarios

    Measurement of the inelastic proton-proton cross section at root s=7 TeV

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    A measurement is presented of the inelastic proton-proton cross section at a centre-of-mass energy of root s = 7 TeV. Using the CMS detector at the LHC, the inelastic cross section is measured through two independent methods based on information from (i) forward calorimetry (for pseudorapidity 3 200 MeV/c. The measurements cover a large fraction of the inelastic cross section for particle production over about nine units of pseudorapidity and down to small transverse momenta. The results are compared with those of other experiments, and with models used to describe high-energy hadronic interactions. (C) 2013 CERN. Published by Elsevier B.V. All rights reserved

    Search for long-lived particles in events with photons and missing energy in proton-proton collisions at root s=7 TeV

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    Results are presented from a search for long-lived neutralinos decaying into a photon and an invisible particle, a signature associated with gauge-mediated supersymmetry breaking in supersymmetric models. The analysis is based on a 4.9 fb(-1) sample of proton-proton collisions at root s = 7 TeV, collected with the CMS detector at the LHC. The missing transverse energy and the time of arrival of the photon at the electromagnetic calorimeter are used to search for an excess of events over the expected background. No significant excess is observed, and lower limits at the 95% confidence level are obtained on the mass of the lightest neutralino, m > 220 GeV (for c tau 6000 mm (for m < 150 GeV). (c) 2013 CERN. Published by Elsevier B.V. All rights reserved

    Inclusive and differential measurements of the t(t)over-bar charge asymmetry in pp collisions at root s=8 TeV

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    The charge asymmetry is measured in proton–proton collisions at a centre-of-mass energy of . The data, collected with the CMS experiment at the LHC, correspond to an integrated luminosity of 19.7 fb−1. Selected events contain an electron or a muon and four or more jets, where at least one jet is identified as originating from b-quark hadronization. The inclusive charge asymmetry is found to be . In addition, differential charge asymmetries as a function of rapidity, transverse momentum, and invariant mass of the system are studied. For the first time at the LHC, the measurements are also performed in a reduced fiducial phase space of top quark pair production, with an integrated result of . All measurements are consistent within two standard deviations with zero asymmetry as well as with the predictions of the standard model

    Search for anomalous single top quark production in association with a photon in pp collisions at √s=8 TeV

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