1,510 research outputs found

    Anomalous temperature dependence of surface tension and capillary waves at liquid gallium

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    The temperature dependence of surface tension \gamma(T) at liquid gallium is studied theoretically and experimentally using light scattering from capillary waves. The theoretical model based on the Gibbs thermodynamics relates the temperature derivative of \gamma to the surface excess entropy -\Delta S. Although capillary waves contribute to the surface entropy with a positive sign the effect of dipole layer on \Delta S is negative. Experimental data collected at a free Ga surface in the temperature range from 30 to 160 C show that the temperature derivative of the tension changes sign near 100 C.Comment: 11 pages, 1 Postscript figure, submitted to J. Phys.

    Excavations at Mission San Jose Y San Miguel de Aguayo, San Antonio, Texas

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    This report details an archaeological study of Mission San Jose y San Miguel de Aguayo conducted during the spring and summer of 1993. The study was undertaken by the Center for Archaeological Research of The University of Texas at San Antonio, in accordance with a contract between the National Park Service (owner) and Cox/Croslin and Associates (sponsor). The principal research objective focused on determining the extent of impact the planned visitors\u27 center construction and improvements would have on the mission\u27s Spanish colonial features. Backhoe trenching, shovel testing, and unit excavations were used in the areas to be impacted by the visitors\u27 center. Additionally, shovel testing was conducted on a 50-ft grid within the mission compound to obtain information for future correction of drainage problems. Analyses of ceramics, faunal remains, stratigraphy, and artifact distribution allow inferences concerning diet, temporal contexts, and recognition of intact Colonial deposits. Recommendations are made concerning present and future construction

    The person-centred approach to an ageing society

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    Modern care is often based on investigations such as laboratory markers and imaging - for example, X-ray or ultrasound. The results contribute to a diagnosis and, if judged necessary, treatment is initiated. This diseased-oriented approach is the prevailing mode of management in modern medicine. In contrast, person-centered care (PCC) takes the point of departure from each person\ub4s subjective experience of illness and its impact on daily life. A patient is considered as a person with emotions and feelings. PCC is considered present within clinical care according to a definition articulated by the Centre for Person Centred Care at the University of Gothenburg (GPCC) when three core components are present: elicitation of a detailed patient narrative; formulated partnership between caregiver and patient and documentation of the partnership in the patient record. Accordingly, when there is an illness requiring care and the person is attended using these components, PCC is being applied. In most situations today, PCC is not applied in terms of the narrative and is not fully elicited or the partnership and/or the documentation are not included. It is proposed that the challenge to Society arising from changing demographics can be addressed by implementing PCC and creating an alternative to existing healthcare. The importance and benefits of such an approach on a wider scale is not yet clear as research has been limited to date. Studies in selected patient populations (heart failure and hip fractures), however, have shown promising results. As the population ages, there will be a dramatic increase in healthcare consumption. Even with technological developments, there will be a need for tremendous resources to be dedicated to care. A new organization and attitude from healthcare policymakers and providers above and beyond the present model appears required in order to respond to this demand. As part of such change, person-centred care, with the interaction between healthcare providers and the person of the patient, can facilitate, compensate and develop more effective healthcare services for the future

    Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

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    The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Search for dark matter in events with heavy quarks and missing transverse momentum in pp collisions with the ATLAS detector

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    This article reports on a search for dark matterpair production in association with bottom or top quarks in20.3fb−1ofppcollisions collected at√s=8TeVbytheATLAS detector at the LHC. Events with large missing trans-verse momentum are selected when produced in associationwith high-momentum jets of which one or more are identifiedas jets containingb-quarks. Final states with top quarks areselected by requiring a high jet multiplicity and in some casesa single lepton. The data are found to be consistent with theStandard Model expectations and limits are set on the massscale of effective field theories that describe scalar and tensorinteractions between dark matter and Standard Model par-ticles. Limits on the dark-matter–nucleon cross-section forspin-independent and spin-dependent interactions are alsoprovided. These limits are particularly strong for low-massdark matter. Using a simplified model, constraints are set onthe mass of dark matter and of a coloured mediator suitableto explain a possible signal of annihilating dark matter

    Measurement of the production of a W boson in association with a charm quark in pp collisions at √s = 7 TeV with the ATLAS detector

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    The production of a W boson in association with a single charm quark is studied using 4.6 fb−1 of pp collision data at s√ = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96+0.26−0.30 at Q 2 = 1.9 GeV2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio σ(W + +c¯¯)/σ(W − + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s−s¯¯¯ quark asymmetry

    Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

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    Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations
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