5,194 research outputs found

    Searches for continuous gravitational waves from nine young supernova remnants

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    We describe directed searches for continuous gravitational waves (GWs) in data from the sixth Laser Interferometer Gravitational-wave Observatory (LIGO) science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of 10. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3–25.3 days using the matched-filtering F{\mathcal{F}}-statistic. We found no evidence of GW signals. We set 95% confidence upper limits as strong (low) as 4 × 10?25 on intrinsic strain, 2 × 10?7 on fiducial ellipticity, and 4 × 10?5 on r-mode amplitude. These beat the indirect limits from energy conservation and are within the range of theoretical predictions for neutron-star ellipticities and r-mode amplitudes

    Bridge distress caused by approach embankment settlement

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    Surtees Bridge, which carries the A66(T) over the River Tees near Thornaby-on-Tees in the UK, has been showing signs of distress that predate its opening in 1981. Subsequent investigations have shown that the bridge distress is related to unexpectedly large settlement of the eastern approach embankment. Recent ground investigations prompted by a proposed widening of the river crossing have produced many new data on the alluvial deposits underlying the site, and explain why embankment settlement was so much larger than originally anticipated. Comparison of the geotechnical parameters obtained from the original and more recent ground investigations suggests that the original investigation significantly underestimated the thickness of an alluvial clay layer underlying the site, and that its coefficient of consolidation was overestimated. Settlement analyses using geotechnical data from the original ground investigations predict moderate embankment settlements occurring principally during construction. Settlement analyses based on all the available data predict far larger embankment settlements occurring over extended time periods. The latter analyses predict an embankment settlement similar to that observed and of sufficient magnitude to cause the observed lateral displacement of the bridge due to lateral loading of its piled foundation

    Amicable pairs and aliquot cycles for elliptic curves

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    An amicable pair for an elliptic curve E/Q is a pair of primes (p,q) of good reduction for E satisfying #E(F_p) = q and #E(F_q) = p. In this paper we study elliptic amicable pairs and analogously defined longer elliptic aliquot cycles. We show that there exist elliptic curves with arbitrarily long aliqout cycles, but that CM elliptic curves (with j not 0) have no aliqout cycles of length greater than two. We give conjectural formulas for the frequency of amicable pairs. For CM curves, the derivation of precise conjectural formulas involves a detailed analysis of the values of the Grossencharacter evaluated at a prime ideal P in End(E) having the property that #E(F_P) is prime. This is especially intricate for the family of curves with j = 0.Comment: 53 page

    Educating Health Professionals about Disability: A Review of Interventions

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    Health professionals need to understand the human rights and health needs of disabled people. This review of evidence on interventions demonstrates that a range of often innovative approaches have been trialled. Lectures by faculty are less effective in changing attitudes than contact with disabled people themselves. Existing examples of good practice need to be scaled up, and better and more long-term evaluations of impact are required

    Search for WW and WZ production in lepton plus jets final state at CDF

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    We present a search for WW and WZ production in final states that contain a charged lepton (electron or muon) and at least two jets, produced in sqrt(s) = 1.96 TeV ppbar collisions at the Fermilab Tevatron, using data corresponding to 1.2 fb-1 of integrated luminosity collected with the CDF II detector. Diboson production in this decay channel has yet to be observed at hadron colliders due to the large single W plus jets background. An artificial neural network has been developed to increase signal sensitivity, as compared with an event selection based on conventional cuts. We set a 95% confidence level upper limit of sigma_{WW}* BR(W->lnu,W->jets)+ sigma_{WZ}*BR(W->lnu,Z->jets)We present a search for WW and WZ production in final states that contain a charged lepton (electron or muon) and at least two jets, produced in √s=1.96  TeV pp̅ collisions at the Fermilab Tevatron, using data corresponding to 1.2  fb-1 of integrated luminosity collected with the CDF II detector. Diboson production in this decay channel has yet to be observed at hadron colliders due to the large single W plus jets background. An artificial neural network has been developed to increase signal sensitivity, as compared with an event selection based on conventional cuts. We set a 95% confidence level upper limit of σWW×BR(W→ℓνℓ,W→jets)+σWZ×BR(W→ℓνℓ,Z→jets)<2.88  pb, which is consistent with the standard model next-to-leading-order cross section calculation for this decay channel of 2.09±0.12  pb.Peer reviewe

    Reviewing research evidence and the case of participation in sport and physical recreation by black and minority ethnic communities

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    The paper addresses the implications of using the process of systematic review in the many areas of leisure where there is a dearth of material that would be admitted into conventional Cochrane Reviews. This raises important questions about what constitutes legitimate knowledge, questions that are of critical import not just to leisure scholars, but to the formulation of policy. The search for certainty in an area that lacks conceptual consensus results in an epistemological imperialism that takes a geocentric form. While clearly, there is a need for good research design whatever the style of research, we contend that the wholesale rejection of insightful research is profligate and foolhardy. A mechanism has to be found to capitalise on good quality research of whatever form. In that search, we draw upon our experience of conducting a review of the material available on participation in sport and physical recreation by people from Black and minority ethnic groups. The paper concludes with a proposal for a more productive review process that makes better use of the full panoply of good quality research available. © 2012 © 2012 Taylor & Francis

    Production Processes as a Tool to Study Parameterizations of Quark Confinement

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    We introduce diquarks as separable correlations in the two-quark Green's function to facilitate the description of baryons as relativistic three-quark bound states. These states then emerge as solutions of Bethe-Salpeter equations for quarks and diquarks that interact via quark exchange. When solving these equations we consider various dressing functions for the free quark and diquark propagators that prohibit the existence of corresponding asymptotic states and thus effectively parameterize confinement. We study the implications of qualitatively different dressing functions on the model predictions for the masses of the octet baryons as well as the electromagnetic and strong form factors of the nucleon. For different dressing functions we in particular compare the predictions for kaon photoproduction, γpKΛ\gamma p\to K\Lambda, and associated strangeness production, pppKΛpp\to pK\Lambda with experimental data. This leads to conclusions on the permissibility of different dressing functions.Comment: 43 pages, Latex, 28 eps files included via epsfig; version to be published in Physical Review

    Stacked Search for Gravitational Waves from the 2006 SGR 1900+14 Storm

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    We present the results of a LIGO search for short-duration gravitational waves (GWs) associated with the 2006 March 29 SGR 1900+14 storm. A new search method is used, "stacking'' the GW data around the times of individual soft-gamma bursts in the storm to enhance sensitivity for models in which multiple bursts are accompanied by GW emission. We assume that variation in the time difference between burst electromagnetic emission and potential burst GW emission is small relative to the GW signal duration, and we time-align GW excess power time-frequency tilings containing individual burst triggers to their corresponding electromagnetic emissions. We use two GW emission models in our search: a fluence-weighted model and a flat (unweighted) model for the most electromagnetically energetic bursts. We find no evidence of GWs associated with either model. Model-dependent GW strain, isotropic GW emission energy E_GW, and \gamma = E_GW / E_EM upper limits are estimated using a variety of assumed waveforms. The stacking method allows us to set the most stringent model-dependent limits on transient GW strain published to date. We find E_GW upper limit estimates (at a nominal distance of 10 kpc) of between 2x10^45 erg and 6x10^50 erg depending on waveform type. These limits are an order of magnitude lower than upper limits published previously for this storm and overlap with the range of electromagnetic energies emitted in SGR giant flares.Comment: 7 pages, 3 figure

    Positive youth development in swimming: clarification and consensus of key psychosocial assets

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    The purpose of this study was to gain a more cohesive understanding of the assets considered necessary to develop in young swimmers to ensure both individual and sport specific development. This two stage study involved (a) a content analysis of key papers to develop a list of both psychosocial skills for performance enhancement and assets associated with positive youth development, and (b) in-depth interviews involving ten expert swim coaches, practitioners and youth sport scholars. Five higher order categories containing seventeen individual assets emerged. These results are discussed in relation to both existing models of positive youth development and implications for coaches, practitioners and parents when considering the psychosocial development of young British swimmers
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