1,720 research outputs found

    Reworking the Tucson-Melbourne Three-Nucleon Potential

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    We introduce new values of the strength constants (i.e., aa, bb, cc, and dd coefficients) of the Tucson-Melbourne (TM) 2π\pi exchange three nucleon potential. The new values come from contemporary dispersion relation analyses of meson factory π\piN scattering data. We make variational Monte Carlo calculations of the triton with the original and updated three-body forces to study the effects of this update. We remove a short-range -- π\pi-range part of the potential due to the cc coefficient and discuss the effect on the triton binding energy.Comment: 12 pages, to appear in Few-Body System

    Analysis of three-nucleon forces effects in the A=3A=3 system

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    Using modern nucleon-nucleon interactions in the description of the A=3,4A=3,4 nuclear systems the χ2\chi^2 per datum results to be much bigger than one. In particular it is not possible to reproduce the three- and four-nucleon binding energies and the ndn-d scattering length simultaneously. This is one manifestation of the necessity of including a three-nucleon force in the nuclear Hamiltonian. In this paper we perform an analysis of some, widely used, three-nucleon force models. We analyze their capability to describe the aforementioned quantities and, to improve their description, we propose modifications in the parametrization of the models. The effects of these new parametrization are studied in some polarization observables at low energies.Comment: 10 pages, to be published in Few-Body Systems. Presented at the workshop on "Relativistic Description of Two- and Three-body Systems in Nuclear Physics" ECT* Trento, 19 - 23 October 200

    ρ\rho-ω\omega mixing and spin dependent CSV potential

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    We construct the charge symmetry violating (CSV) nucleon-nucleon potential induced by the ρ0\rho^0-\o mixing due to the neutron-proton mass difference driven by the NNNN loop. Analytical expression for for the two-body CSV potential is presented containing both the central and non- central NNNN interaction. We show that the ρ\rhoNNNN tensor interaction can significantly enhance the charge symmetry violating NNNN interaction even if momentum dependent off-shell ρ0\rho^0-ω\omega mixing amplitude is considered. It is also shown that the inclusion of form factors removes the divergence arising out of the contact interaction. Consequently, we see that the precise size of the computed scattering length difference depends on how the short range aspects of the CSV potential are treated.Comment: Accepted for publication in Phys. Rev.

    Effectiveness of pharmacist home visits for individuals at risk of medication-related problems: A systematic review and meta-analysis of randomised controlled trials

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    This is the final version. Available on open access from BMC via the DOI in this recordAvailability of data and materials: Not applicable, as this research article reviewed the published literature. The data published may be found in the original manuscripts cited in the references list.Background: Medication mismanagement is a major cause of both hospital admission and nursing home placement of frail older adults. Medication reviews by community pharmacists aim to maximise therapeutic benefit but also minimise harm. Pharmacist-led medication reviews have been the focus of several systematic reviews, but none have focussed on the home setting. Review methods: To determine the effectiveness of pharmacist home visits for individuals at risk of medication-related problems we undertook a systematic review and meta-analysis of randomised controlled trials (RCTs). Thirteen databases were searched from inception to December 2018. Forward and backward citation of included studies was also performed. Articles were screened for inclusion independently by two reviewers. Randomised controlled studies of home visits by pharmacists for individuals at risk of medication-related problems were eligible for inclusion. Data extraction and quality appraisal were performed by one reviewer and checked by a second. Random-effects meta-analyses were performed where sufficient data allowed and narrative synthesis summarised all remaining data. Results: Twelve RCTs (reported in 15 articles), involving 3410 participants, were included in the review. The frequency, content and purpose of the home visit varied considerably. The data from eight trials were suitable for meta-analysis of the effects on hospital admissions and mortality, and from three trials for the effects on quality of life. Overall there was no evidence of reduction in hospital admissions (risk ratio (RR) of 1.01 (95%CI 0.86 to 1.20, I2 = 69.0%, p = 0.89; 8 studies, 2314 participants)), or mortality (RR of 1.01 (95%CI 0.81 to 1.26, I2 = 0%, p = 0.94; 8 studies, 2314 participants)). There was no consistent evidence of an effect on quality of life, medication adherence or knowledge. Conclusion: A systematic review of twelve RCTs assessing the impact of pharmacist home visits for individuals at risk of medication related problems found no evidence of effect on hospital admission or mortality rates, and limited evidence of effect on quality of life. Future studies should focus on using more robust methods to assess relevant outcomes.National Institute for Health Research (NIHR

    Whole-system approaches to improving the health and wellbeing of healthcare workers: A systematic review

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    This is the final version of the article. Available from Public Library of Science via the DOI in this record.BACKGROUND: Healthcare professionals throughout the developed world report higher levels of sickness absence, dissatisfaction, distress, and "burnout" at work than staff in other sectors. There is a growing call for the 'triple aim' of healthcare delivery (improving patient experience and outcomes and reducing costs; to include a fourth aim: improving healthcare staff experience of healthcare delivery. A systematic review commissioned by the United Kingdom's (UK) Department of Health reviewed a large number of international healthy workplace interventions and recommended five whole-system changes to improve healthcare staff health and wellbeing: identification and response to local need, engagement of staff at all levels, and the involvement, visible leadership from, and up-skilling of, management and board-level staff. OBJECTIVES: This systematic review aims to identify whole-system healthy workplace interventions in healthcare settings that incorporate (combinations of) these recommendations and determine whether they improve staff health and wellbeing. METHODS: A comprehensive and systematic search of medical, education, exercise science, and social science databases was undertaken. Studies were included if they reported the results of interventions that included all healthcare staff within a healthcare setting (e.g. whole hospital; whole unit, e.g. ward) in collective activities to improve physical or mental health or promote healthy behaviours. RESULTS: Eleven studies were identified which incorporated at least one of the whole-system recommendations. Interventions that incorporated recommendations to address local need and engage the whole workforce fell in to four broad types: 1) pre-determined (one-size-fits-all) and no choice of activities (two studies); or 2) pre-determined and some choice of activities (one study); 3) A wide choice of a range of activities and some adaptation to local needs (five studies); or, 3) a participatory approach to creating programmes responsive and adaptive to local staff needs that have extensive choice of activities to participate in (three studies). Only five of the interventions included substantial involvement and engagement of leadership and efforts aimed at up-skilling the leadership of staff to support staff health and wellbeing. Incorporation of more of the recommendations did not appear to be related to effectiveness. The heterogeneity of study designs, populations and outcomes excluded a meta-analysis. All studies were deemed by their authors to be at least partly effective. Two studies reported statistically significant improvement in objectively measured physical health (BMI) and eight in subjective mental health. Six studies reported statistically significant positive changes in subjectively assessed health behaviours. CONCLUSIONS: This systematic review identified 11 studies which incorporate at least one of the Boorman recommendations and provides evidence that whole-system healthy workplace interventions can improve health and wellbeing and promote healthier behaviours in healthcare staff.Funding provided in part to the European Centre for Environment and Human Health (part of the University of Exeter Medical School) by the European Regional Development Fund Programme 2007 to 2013 (https://www.gov.uk/guidance/erdf-programmes-and-resources) and European Social Fund Convergence Programme for Cornwall and the Isles of Scilly (http://www.erdfconvergence.org.uk/esf). This research was also funded in part by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care South West Peninsula (http://clahrc-peninsula.nihr.ac.uk/) at the Royal Devon and Exeter NHS Foundation Trust (http://www.rdehospital.nhs.uk/). The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    Charge-Asymmetry of the Nucleon-Nucleon Interaction

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    Based upon the Bonn meson-exchange model for the nucleon-nucleon (NNNN) interaction, we study systematically the charge-symmetry-breaking (CSB) of the NNNN interaction due to nucleon mass splitting. Particular attention is payed to CSB generated by the 2π2\pi-exchange contribution to the NNNN interaction, πρ\pi\rho diagrams, and other multi-meson-exchanges. We calculate the CSB differences in the 1S0^1S_0 effective range parameters as well as phase shift differences in SS, PP and higher partial waves up to 300 MeV lab. energy. We find a total CSB difference in the singlet scattering length of 1.6 fm which explains the empirical value accurately. The corresponding CSB phase-shift differences are appreciable at low energy in the 1S0^1S_0 state. In the other partial waves, the CSB splitting of the phase shifts is small and increases with energy, with typical values in the order of 0.1 deg at 300 MeV in PP and DD waves.Comment: 11 pages, RevTex, 14 figure

    The one-pion-exchange three-nucleon force and the AyA_y puzzle

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    We consider a new three-nucleon force generated by the exchange of one pion in the presence of a 2N correlation. The underlying irreducible diagram has been recently suggested by the authors as a possible candidate to explain the puzzle of the vector analyzing powers AyA_y and iT11iT_{11} for nucleon-deuteron scattering. Herein, we have calculated the elastic neutron-deuteron differential cross section, AyA_y, iT11iT_{11}, T20T_{20}, T21T_{21}, and T22T_{22} below break-up threshold by accurately solving the Alt-Grassberger-Sandhas equations with realistic interactions. We have also studied how AyA_y evolves below 30 MeV. The results indicate that this new 3NF diagram provides one possible additional contribution, with the correct spin-isospin structure, for the explanation of the origin of this puzzle.Comment: revised version: We have also studied how Ay evolves below 30 MeV, 4 Pages (twocolumn), 2 figures, uses psfig, RevTe

    Three-Nucleon Force Effects in Nucleon Induced Deuteron Breakup: Predictions of Current Models (I)

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    An extensive study of three-nucleon force effects in the entire phase space of the nucleon-deuteron breakup process, for energies from above the deuteron breakup threshold up to 200 MeV, has been performed. 3N Faddeev equations have been solved rigorously using the modern high precision nucleon-nucleon potentials AV18, CD Bonn, Nijm I, II and Nijm 93, and also adding 3N forces. We compare predictions for cross sections and various polarization observables when NN forces are used alone or when the two pion-exchange Tucson-Melbourne 3NF was combined with each of them. In addition AV18 was combined with the Urbana IX 3NF and CD Bonn with the TM' 3NF, which is a modified version of the TM 3NF, more consistent with chiral symmetry. Large but generally model dependent 3NF effects have been found in certain breakup configurations, especially at the higher energies, both for cross sections and spin observables. These results demonstrate the usefulness of the kinematically complete breakup reaction in testing the proper structure of 3N forces.Comment: 42 pages, 20 ps figures, 2 gif figure
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