623 research outputs found

    A MERLIN Observation of PSR B1951+32 and its associated Plerion

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    In an investigative 16 hour L band observation using the MERLIN radio interferometric array, we have resolved both the pulsar PSR B1951+32 and structure within the flat spectral radio continuum region, believed to be the synchrotron nebula associated with the interaction of the pulsar and its `host' supernova remnant CTB 80. The extended structure we see, significant at \sim 4.5 σ\sigma, is of dimensions 2.5" ×\times 0.75", and suggests a sharp bow shaped arc of shocked emission, which is correlated with similar structure observed in lower resolution radio maps and X-ray images. Using this MERLIN data as a new astrometric reference for other multiwavelength data we can place the pulsar at one edge of the HST reported optical synchrotron knot, ruling out previous suggested optical counterparts, and allowing an elementary analysis of the optical synchrotron emission which appears to trail the pulsar. The latter is possibly a consequence of pulsar wind replenishment, and we suggest that the knot is a result of magnetohydrodynamic (MHD) instabilities. These being so, it suggests a dynamical nature to the optical knot, which will require high resolution optical observations to confirm.Comment: 12 pages, 2 figures. Accepted for publication in ApJ

    Magnetohydrodynamic activity inside a sphere

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    We present a computational method to solve the magnetohydrodynamic equations in spherical geometry. The technique is fully nonlinear and wholly spectral, and uses an expansion basis that is adapted to the geometry: Chandrasekhar-Kendall vector eigenfunctions of the curl. The resulting lower spatial resolution is somewhat offset by being able to build all the boundary conditions into each of the orthogonal expansion functions and by the disappearance of any difficulties caused by singularities at the center of the sphere. The results reported here are for mechanically and magnetically isolated spheres, although different boundary conditions could be studied by adapting the same method. The intent is to be able to study the nonlinear dynamical evolution of those aspects that are peculiar to the spherical geometry at only moderate Reynolds numbers. The code is parallelized, and will preserve to high accuracy the ideal magnetohydrodynamic (MHD) invariants of the system (global energy, magnetic helicity, cross helicity). Examples of results for selective decay and mechanically-driven dynamo simulations are discussed. In the dynamo cases, spontaneous flips of the dipole orientation are observed.Comment: 15 pages, 19 figures. Improved figures, in press in Physics of Fluid

    A multinational cross-sectional survey of the management of patient medication adherence by European healthcare professionals

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    Objectives To examine which interventions healthcare professionals use to support patients with taking medicines and their perceptions about the effectiveness of those actions. Design Cross-sectional multinational study. Setting Online survey in Austria, Belgium, England, France, Germany, Hungary, The Netherlands, Poland, Portugal and Switzerland. Participants A total of 3196 healthcare professionals comprising doctors (855), nurses (1047) and pharmacists (1294) currently registered and practising in primary care and community settings. Main outcome measures Primary outcome: Responses to the question ‘I ask patients if they have missed any doses of their medication’ for each profession and in each country. Secondary outcome: Responses to 50 items concerning healthcare professional behaviour to support patients with medication-taking for each profession and in each country. Results Approximately half of the healthcare professionals in the survey ask patients with long-term conditions whether they have missed any doses of their medication on a regular basis. Pharmacists persistently report that they intervene less than the other two professions to support patients with medicines. No country effects were found for the primary outcome. Conclusions Healthcare professionals in Europe are limited in the extent to which they intervene to assist patients having long-term conditions with medication adherence. This represents a missed opportunity to support people with prescribed treatment. These conclusions are based on the largest international survey to date of healthcare professionals’ management of medication adherence

    Protocol for a pragmatic feasibility randomised controlled trial of peer coaching for adults with long-term conditions: PEER CONNECT.

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    INTRODUCTION: Patients with low levels of knowledge, skills and confidence to manage their health and well-being (activation) are more likely to have unmet health needs, delay seeking healthcare and need emergency care. National Health Service England estimates that this may be applicable to 25%-40% of patients with long-term health conditions. Volunteer peer coaching may support people to increase their level of activation. This form of intervention may be particularly effective for people with low levels of activation. METHODS AND ANALYSIS: This single site, two-arm randomised controlled trial has been designed to assess the feasibility of conducting a definitive trial of volunteer peer health and well-being coaching for people with long-term health conditions (multiple sclerosis, rheumatic diseases or chronic pain) and low activation. Feasibility outcomes include recruitment and retention rates, and intervention adherence. We will measure patient activation, mental health and well-being as potential outcomes for a definitive trial. These outcomes will be summarised descriptively for each time point by allocated group and help to inform sample size calculation for the definitive trial. Criteria for progression to a full trial will be used. ETHICS AND DISSEMINATION: Ethical approval has been granted by the London - Surrey Research Ethics Committee, reference 21/LO/0715. Results from this feasibility trial will be shared directly with participants, presented at local, regional and national conferences and published in an open-access journal. TRIAL REGISTRATION NUMBER: ISRCTN12623577

    Development Of Al-B-C Master Alloy Under External Fields

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    This study investigates the application of external fields in the development of an Al-B-C alloy, with the aim of synthesizing in situ Al3BC particles. A combination of ultrasonic cavitation and distributive mixing was applied for uniform dispersion of insoluble graphite particles in the Al melt, improving their wettability and its subsequent incorporation into the Al matrix. Lower operating temperatures facilitated the reduction in the amount of large clusters of reaction phases, with Al3BC being identified as the main phase in XRD analysis. The distribution of Al3BC particles was quantitatively evaluated. Grain refinement experiments reveal that Al-B-C alloy can act as a master alloy for Al-4Cu and AZ91D alloys, with average grain size reduction around 50% each at 1wt%Al-1.5B-2C additions

    A review of recent work on discharge characteristics during plasma electrolytic oxidation of various metals

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    The review describes recent progress on understanding and quantification of the various phenomena that take place during plasma electrolytic oxidation, which is in increasing industrial use for production of protective coatings and other surface treatment purposes. A general overview of the process, and some information about usage of these coatings, are provided in the first part of the review. The focus is then on the dielectric breakdown that repeatedly occurs over the surface of the work-piece. These discharges are central to the process, since it is largely via the associated plasmas that oxidation of the substrate takes place and the coating is created. The details are complex, since the discharge characteristics are affected by a number of processing variables. The inter-relationships between electrical conditions, electrolyte composition, coating microstructure and rates of growth, which are linked via the characteristics of the discharges, have become clearer over recent years and these improvements in understanding are summarized here. There is considerable scope for more effective process control, with specific objectives in terms of coating performance and energy efficiency, and an attempt is made to identify key points that are likely to assist this

    “My patients are better than yours”: optimistic bias about patients’ medication adherence by European health care professionals

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    Objectives: The objectives of this study were to determine the perceptions of European physicians, nurses, and pharmacists about the extent of nonadherence by patients in their country relative to their perception of nonadherence by their own patients, and to investigate the occurrence of optimistic bias about medication adherence. The study explored a key cognitive bias for prevalence and likelihood estimates in the context of health care professionals’ beliefs about patients’ use of medicines. Methods: A cross-sectional online survey of 3,196 physicians (855), nurses (1,294), and pharmacists (1,047) in ten European countries (Austria, Belgium, England, France, Germany, Hungary, the Netherlands, Poland, Portugal, and Switzerland) was used. Results: Participants differed in their perceptions of the prevalence of medication adherence initiation, implementation, and persistence present in their own patients with a chronic illness in comparison to patients with a chronic illness in general. Health care professionals demonstrated optimistic bias for initiation and persistence with medicine taking, perceiving their own patients to be more likely to initiate and persist with treatment than other patients, but reported significantly lower prevalence of medication adherence levels for their own patients than for patients in general. This finding is discussed in terms of motivational and cognitive factors that may foster optimistic bias by health care professionals about their patients, including heightened knowledge of, and positive beliefs about, their own professional competence and service delivery relative to care and treatment provided elsewhere. Conclusion: Health care professionals in Europe demonstrated significant differences in their perceptions of medication adherence prevalence by their own patients in comparison to patients in general. Some evidence of optimistic bias by health care professionals about their patients’ behavior is observed. Further social cognitive theory-based research of health care professional beliefs about medication adherence is warranted to enable theory-based practitioner-focused interventions to be tested and implemented

    Processing of aluminum-graphite particulate metal matrix composites by advanced shear technology

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    Copyright @ 2009 ASM International. This paper was published in Journal of Materials Engineering and Performance 18(9) and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this paper for a fee or for commercial purposes, or modification of the content of this paper are prohibited.To extend the possibilities of using aluminum/graphite composites as structural materials, a novel process is developed. The conventional methods often produce agglomerated structures exhibiting lower strength and ductility. To overcome the cohesive force of the agglomerates, a melt conditioned high-pressure die casting (MC-HPDC) process innovatively adapts the well-established, high-shear dispersive mixing action of a twin screw mechanism. The distribution of particles and properties of composites are quantitatively evaluated. The adopted rheo process significantly improved the distribution of the reinforcement in the matrix with a strong interfacial bond between the two. A good combination of improved ultimate tensile strength (UTS) and tensile elongation (e) is obtained compared with composites produced by conventional processes.EPSR

    Smc5/6 coordinates formation and resolution of joint molecules with chromosome morphology to ensure meiotic divisions

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    During meiosis, Structural Maintenance of Chromosome (SMC) complexes underpin two fundamental features of meiosis: homologous recombination and chromosome segregation. While meiotic functions of the cohesin and condensin complexes have been delineated, the role of the third SMC complex, Smc5/6, remains enigmatic. Here we identify specific, essential meiotic functions for the Smc5/6 complex in homologous recombination and the regulation of cohesin. We show that Smc5/6 is enriched at centromeres and cohesin-association sites where it regulates sister-chromatid cohesion and the timely removal of cohesin from chromosomal arms, respectively. Smc5/6 also localizes to recombination hotspots, where it promotes normal formation and resolution of a subset of joint-molecule intermediates. In this regard, Smc5/6 functions independently of the major crossover pathway defined by the MutLγ complex. Furthermore, we show that Smc5/6 is required for stable chromosomal localization of the XPF-family endonuclease, Mus81-Mms4Eme1. Our data suggest that the Smc5/6 complex is required for specific recombination and chromosomal processes throughout meiosis and that in its absence, attempts at cell division with unresolved joint molecules and residual cohesin lead to severe recombination-induced meiotic catastroph
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