3,783 research outputs found

    Multiaxial fatigue crack growth in rail steel.

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    In the introduction to a recent symposium on rolling contact fatigue, R.A.Smith stated that it was difficult to apply our greatly increased understanding of metal fatigue, to rolling contact fatigue, because of "the apparent lack of alternating tensile stresses to drive the cracks." He went on to say "alternating shear stresses are easily found, but the reproduction of continuous crack growth controlled by shear <Mode II in fracture mechanics terms), has proved to be near impossible." This project has demonstrated that under specific conditions this mode of growth does occur. The project began by studying rolling contact fatigue defects, in particular the 'squat' defect in railway lines, and the stress analyses that have been performed on them. It was concluded that the largest stress cycle experienced by the cracks must be a shear stress. It. series of tests were then performed that loaded a crack in pure shear, or a mixture of tension and shear, looking at the effects of using fully reversed shear loading, and the effects of applying tensile mean stresses to reduce the friction on the crack flanks. However these tests all produced less than one millimetre of mode II growth, before the cracks arrested or branched. The final series of tests however applied a tensile load cycle before each shear load cycle. This time coplanar growth was produced, that is the crack grew in the direction of the maximum shear stress. This type of load cycle is a simplification of the load cycle calculated by Bower and Johnson of Cambridge University, where the tensile load is produced by fluid trapped in the crack. Two crack growth rate formulae were produced that fitted the data, indicating that the growth rate was dependent on both the tensile and the shear parts of the cycle

    Prevalence and burden of chronic bronchitis symptoms: results from the BOLD study

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    We studied the prevalence, burden and potential risk factors for chronic bronchitis symptoms in the Burden of Obstructive Lung Disease study. Representative population-based samples of adults aged ≥40 years were selected in participating sites. Participants completed questionnaires and spirometry. Chronic bronchitis symptoms were defined as chronic cough and phlegm on most days for ≥3 months each year for ≥2 years. Data from 24 855 subjects from 33 sites in 29 countries were analysed. There were significant differences in the prevalence of self-reported symptoms meeting our definition of chronic bronchitis across sites, from 10.8% in Lexington (KY, USA), to 0% in Ile-Ife (Nigeria) and Blantyre (Malawi). Older age, less education, current smoking, occupational exposure to fumes, self-reported diagnosis of asthma or lung cancer and family history of chronic lung disease were all associated with increased risk of chronic bronchitis. Chronic bronchitis symptoms were associated with worse lung function, more dyspnoea, increased risk of respiratory exacerbations and reduced quality of life, independent of the presence of other lung diseases. The prevalence of chronic bronchitis symptoms varied widely across the studied sites. Chronic bronchitis symptoms were associated with significant burden both in individuals with chronic airflow obstruction and those with normal lung function

    Attitudes towards persons with mental health conditions and psychosocial disabilities as rights holders in Ghana: a World Health Organization study

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    Background: There are currently major efforts underway in Ghana to address stigma and discrimination, and promote the human rights of those with mental health conditions, within mental health services and the community, working with the World Health Organization’s QualityRights initiative. The present study aims to investigate attitudes towards people with lived experience of mental health conditions and psychosocial disabilities as rights holders. Methods: Stakeholders within the Ghanaian mental health system and community, including health professionals, policy makers, and persons with lived experience, completed the QualityRights pre-training questionnaire. The items examined attitudes towards coercion, legal capacity, service environment, and community inclusion. Additional analyses explored how far participant factors may link to attitudes. Results: Overall, attitudes towards the rights of persons with lived experience were not well aligned with a human rights approach to mental health. Most people supported the use of coercive practices and often thought that health practitioners and family members were in the best position to make treatment decisions. Health/mental health professionals were less likely to endorse coercive measures compared to other groups. Conclusion: This was the first in-depth study assessing attitudes towards persons with lived experience as rights holders in Ghana, and frequently attitudes did not comply with human rights standards, demonstrating a need for training initiatives to combat stigma and discrimination and promote human rights

    Jet production in charged current deep inelastic e⁺p scatteringat HERA

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    The production rates and substructure of jets have been studied in charged current deep inelastic e⁺p scattering for Q² > 200 GeV² with the ZEUS detector at HERA using an integrated luminosity of 110.5 pb⁻¹. Inclusive jet cross sections are presented for jets with transverse energies E_{T}^{jet} > 5 GeV. Measurements of the mean subjet multiplicity, 〈n_{sbj}〉, of the inclusive jet sample are presented. Predictions based on parton-shower Monte Carlo models and next-to-leading-order QCD calculations are compared to the measurements. The value of α_{s} (M_{z}), determined from 〈n_{sbj}〉 at y_{cut} = 10⁻² for jets with 25 < E_{T}^{jet} < 119 GeV, is α_{s} (M_{z}) = 0.1202 ± 0.0052 (stat.)_{-0.0019}^{+0.0060} (syst.)_{-0.0053}^{+0.0065} (th.). The mean subjet multiplicity as a function of Q² is found to be consistent with that measured in NC DIS

    An NLO QCD analysis of inclusive cross-section and jet-production data from the ZEUS experiment

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    The ZEUS inclusive differential cross-section data from HERA, for charged and neutral current processes taken with e+ and e- beams, together with differential cross-section data on inclusive jet production in e+ p scattering and dijet production in \gamma p scattering, have been used in a new NLO QCD analysis to extract the parton distribution functions of the proton. The input of jet data constrains the gluon and allows an accurate extraction of \alpha_s(M_Z) at NLO; \alpha_s(M_Z) = 0.1183 \pm 0.0028(exp.) \pm 0.0008(model) An additional uncertainty from the choice of scales is estimated as \pm 0.005. This is the first extraction of \alpha_s(M_Z) from HERA data alone.Comment: 37 pages, 14 figures, to be submitted to EPJC. PDFs available at http://durpdg.dur.ac.uk/hepdata in LHAPDFv

    The UKIRT Hemisphere Survey: Definition and Full J-band Data Release

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    This paper defines the UK Infra-red Telescope (UKIRT) Hemisphere Survey (UHS) and release of the complete J-band dataset. The UHS provides continuous coverage in the northern hemisphere from a declination of 0 deg to 60 deg by combining the existing Large Area Survey, Galactic Plane Survey and Galactic Clusters Survey conducted under the UKIRT Infra-red Deep Sky Survey (UKIDSS) programme with a new additional ~12,700 sq.deg area not covered by UKIDSS. This data release includes J-band imaging and source catalogues over the new area, which, together with UKIDSS, completes the J-band UHS coverage over the full ~17,900 sq.deg area. 98 per cent of the data in this release have passed quality control criteria, the remaining 2 per cent being scheduled for re-observation. The median 5-sigma point source sensitivity of the released data is 19.6 mag (Vega). The median full width at half-maximum of the point spread function across the dataset is 0.75 arcsec. In this paper, we outline the survey management, data acquisition, processing and calibration, quality control and archiving as well as summarising the characteristics of the released data products. The data are initially available to a limited consortium with a world-wide release scheduled for August 2018

    Inclusive jet cross sections and dijet correlations in D±D^{*\pm} photoproduction at HERA

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    Inclusive jet cross sections in photoproduction for events containing a DD^* meson have been measured with the ZEUS detector at HERA using an integrated luminosity of 78.6pb178.6 {\rm pb}^{-1}. The events were required to have a virtuality of the incoming photon, Q2Q^2, of less than 1 GeV2^2, and a photon-proton centre-of-mass energy in the range 130<Wγp<280GeV130<W_{\gamma p}<280 {\rm GeV}. The measurements are compared with next-to-leading-order (NLO) QCD calculations. Good agreement is found with the NLO calculations over most of the measured kinematic region. Requiring a second jet in the event allowed a more detailed comparison with QCD calculations. The measured dijet cross sections are also compared to Monte Carlo (MC) models which incorporate leading-order matrix elements followed by parton showers and hadronisation. The NLO QCD predictions are in general agreement with the data although differences have been isolated to regions where contributions from higher orders are expected to be significant. The MC models give a better description than the NLO predictions of the shape of the measured cross sections.Comment: 43 pages, 12 figures, charm jets ZEU

    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
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