9 research outputs found

    Measurement of the Z/gamma* + b-jet cross section in pp collisions at 7 TeV

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    The production of b jets in association with a Z/gamma* boson is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7 TeV and recorded by the CMS detector. The inclusive cross section for Z/gamma* + b-jet production is measured in a sample corresponding to an integrated luminosity of 2.2 inverse femtobarns. The Z/gamma* + b-jet cross section with Z/gamma* to ll (where ll = ee or mu mu) for events with the invariant mass 60 < M(ll) < 120 GeV, at least one b jet at the hadron level with pT > 25 GeV and abs(eta) < 2.1, and a separation between the leptons and the jets of Delta R > 0.5 is found to be 5.84 +/- 0.08 (stat.) +/- 0.72 (syst.) +(0.25)/-(0.55) (theory) pb. The kinematic properties of the events are also studied and found to be in agreement with the predictions made by the MadGraph event generator with the parton shower and the hadronisation performed by PYTHIA.Comment: Submitted to the Journal of High Energy Physic

    QUALITY OF SEED LOTS OF SOYBEAN [Glycine max (L.) MERRILL] GENOTYPES PRODUCED IN A GUINEA SAVANNA AGROECOLOGY OF GHANA

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    Crop yield is a derivative of the number of plants harvested. In Ghana, soybean fields are mostly sparsely populated with less than the optimum number of plants, a phenomenon that contributes to poor yields of only 46% of the crop’s potential in farmers’ fields. The low plant population could be the result of the poor quality of the seed planted. Meanwhile, the quality of seed is determined by crop production practices, the environmental conditions of the mother plant, and postharvest handling technologies used. Over 90% of the country’s soybean seed comes from the northern part of Ghana, predominantly the Guinea Savannah. In this study, seed lots of soybean genotypes produced within the Savanna Agroecological Zone of Ghana, were evaluated for physical and physiological traits, and the prevalence of seed borne fungi. Results showed that seed lots produced within the zone and stored under ambient conditions have medium-sized (100 to 140 g/1000 seeds) seeds with an average seed weight of 133 g/1000 seeds. The seed lots evaluated had physical purity values higher than the minimum certification standard of 98% for soybean seed in Ghana. Wrinkled seeds were the most dominant component of the seed with visual defects followed closely by seeds that were discoloured, cracked, and those with purple stains. Aspergillus flavus, Aspergillus niger, Chaetomium globosum, Rhizopus sp and Macrophomina phaseolina were the main fungi identified. Furthermore, the seed lots had an average germination percentage of 86%, which is within the acceptable minimum certification standards for soybean seed in Ghana. Though germination and vigour were variable among the seed lots tested, these parameters were not affected by the presence of the fungi species identified and the amount of seed with visual defects. The findings of this study strongly suggest that the low plant density and the resultant poor yields of soybean usually recorded in farmers’ fields in Ghana are likely due to suboptimal seeding rates at planting coupled with the low use of good agronomic practices with only a small fraction attributable to poor seed quality

    QUALITY OF SEED LOTS OF SOYBEAN [Glycine max (L.) MERRILL] GENOTYPES PRODUCED IN A GUINEA SAVANNA AGROECOLOGY OF GHANA

    No full text
    Crop yield is a derivative of the number of plants harvested. In Ghana, soybean fields are mostly sparsely populated with less than the optimum number of plants, a phenomenon that contributes to poor yields of only 46% of the crop’s potential in farmers’ fields. The low plant population could be the result of the poor quality of the seed planted. Meanwhile, the quality of seed is determined by crop production practices, the environmental conditions of the mother plant, and postharvest handling technologies used. Over 90% of the country’s soybean seed comes from the northern part of Ghana, predominantly the Guinea Savannah. In this study, seed lots of soybean genotypes produced within the Savanna Agroecological Zone of Ghana, were evaluated for physical and physiological traits, and the prevalence of seed borne fungi. Results showed that seed lots produced within the zone and stored under ambient conditions have medium-sized (100 to 140 g/1000 seeds) seeds with an average seed weight of 133 g/1000 seeds. The seed lots evaluated had physical purity values higher than the minimum certification standard of 98% for soybean seed in Ghana. Wrinkled seeds were the most dominant component of the seed with visual defects followed closely by seeds that were discoloured, cracked, and those with purple stains. Aspergillus flavus, Aspergillus niger, Chaetomium globosum, Rhizopus sp and Macrophomina phaseolina were the main fungi identified. Furthermore, the seed lots had an average germination percentage of 86%, which is within the acceptable minimum certification standards for soybean seed in Ghana. Though germination and vigour were variable among the seed lots tested, these parameters were not affected by the presence of the fungi species identified and the amount of seed with visual defects. The findings of this study strongly suggest that the low plant density and the resultant poor yields of soybean usually recorded in farmers’ fields in Ghana are likely due to suboptimal seeding rates at planting coupled with the low use of good agronomic practices with only a small fraction attributable to poor seed quality

    Adaptation to compound climate risks: A systematic global stocktake

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    This article provides a stocktake of the adaptation literature between 2013 and 2019 to better understand how adaptation responses affect risk under the particularly challenging conditions of compound climate events. Across 39 countries, 45 response types to compound hazards display anticipatory (9%), reactive (33%), and maladaptive (41%) characteristics, as well as hard (18%) and soft (68%) limits to adaptation. Low income, food insecurity, and access to institutional resources and finance are the most prominent of 23 vulnerabilities observed to negatively affect responses. Risk for food security, health, livelihoods, and economic outputs are commonly associated risks driving responses. Narrow geographical and sectoral foci of the literature highlight important conceptual, sectoral, and geographic areas for future research to better understand the way responses shape risk. When responses are integrated within climate risk assessment and management, there is greater potential to advance the urgency of response and safeguards for the most vulnerable

    Cervical Cancer Screening among University Students in South Africa: A Theory Based Study

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    Cervical cancer is a serious public health problem in South Africa. Even though the screening is free in health facilities in South Africa, the Pap smear uptake is very low. The objective of the study is to investigate the knowledge and beliefs of female university students in South Africa.A cross sectional study was conducted among university women in South Africa to elicit information about knowledge and beliefs, and screening history.A total of 440 students completed the questionnaire. The average age of the participants was 20.39 years (SD  = 1.71 years). Regarding cervical cancer, 55.2% (n = 243) had ever heard about it. Results indicated that only 15% (22/147) of the students who had ever had sex and had heard about cervical cancer had taken a Pap test. Pearson correlation analysis showed that cervical cancer knowledge had a significantly negative relationship with barriers to cervical cancer screening. Susceptibility and seriousness score were significantly moderately correlated with benefit and motivation score as well as barrier score. Self-efficacy score also had a moderate correlation with benefit and motivation score. Students who had had a Pap test showed a significantly lower score in barriers to being screened compared to students who had not had a Pap test.This study showed that educated women in South Africa lack complete information on cervical cancer. Students who had had a Pap test had significantly lower barriers to cervical cancer screening than those students who had not had a Pap test

    Nutrient acquisition strategies in agroforestry systems

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    Measurement of the ttˉ production cross section in pp collisions at √s=7 TeV using the kinematic properties of events with leptons and jets

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    A measurement of the t (t) over bar production cross section in proton-proton collisions at a centre-of-mass energy of 7 TeV has been performed at the LHC with the CMS detector. The analysis uses a data sample corresponding to an integrated luminosity of 36 pb(-1) and is based on the reconstruction of the final state with one isolated, high transverse-momentum electron or muon and three or more hadronic jets. The kinematic properties of the events are used to separate the t (t) over bar signal from W+jets and QCD multijet background events. The measured cross section is 173(-32)(+39) (stat. + syst.) pb, consistent with standard model expectations

    Shape, transverse size, and charged-hadron multiplicity of jets in pp collisions at sqrts=7;TeV sqrt {s} = 7;TeV

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    Measurements of jet characteristics from inclusive jet production in proton-proton collisions at a centre-of-mass energy of 7 TeV are presented. The data sample was collected with the CMS detector at the LHC during 2010 and corresponds to an integrated luminosity of 36 inverse picobarns. The mean charged hadron multiplicity, the differential and integral jet shape distributions, and two independent moments of the shape distributions are measured as functions of the jet transverse momentum for jets reconstructed with the anti-kT algorithm. The measured observables are corrected to the particle level and compared with predictions from various QCD Monte Carlo generators.Comment: Replaced with published version. Added journal reference and DOI. Supplementary data tables availabl

    Search for the standard model Higgs boson decaying to W+W−W^{+}W^{-} in the fully leptonic final state in pp collisions at s\sqrt{s} = 7 TeV

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    A search for the standard model Higgs boson decaying to W+W- in pp collisions at sqrt(s) = 7 TeV is reported. The data are collected at the LHC with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. The W+W- candidates are selected in events with two charged leptons and large missing transverse energy. No significant excess of events above the standard model background expectations is observed, and upper limits on the Higgs boson production relative to the standard model Higgs expectation are derived. The standard model Higgs boson is excluded in the mass range 129-270 GeV at 95% confidence level.Comment: Submitted to Physics Letters
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