518 research outputs found

    Assessment of throwing arm biomechanics with a motusBASEBALLTM pitching sleeve during long-toss throws and pitching in college baseball pitchers

    Get PDF
    In baseball, long-toss throws are commonly used in return-to-throw programs and for general conditioning; however, the majority of these programs are based on conventional wisdom. Few studies have examined the biomechanics of long-toss throwing and the impact of throw distance. The purpose of this study was to determine if significant differences exist among commonly-used sub-maximal distance long-toss throws and mound pitching. Nineteen college baseball pitchers (19 ± 1.3 years; 88.3 ± 8.4 kg; and 73.9 ± 18.6 cm) wore a motusBASEBALL™ sleeve and sensor which measured peak elbow varus torque (VT), peak forearm angular velocity (Vmax), and peak arm-cocking angle (ACA). Each player completed five long-toss throws at distances of 27 m, 37 m, 46 m, 55 m and five pitches from a mound at regulation (18.4 m). There were no significant differences among throwing conditions for both VT and Vmax (p<0.05). For ACA, there was a significant increase (approximately 12°) as the long-toss distance increased. Coaches and trainers should be aware that sub-maximal distance long-toss throws (27 - 55 m+) generate high-magnitude throwing arm biomechanics (kinetics, velocities, range of motion) that approach or even exceed those generated during pitching; precaution needs to be used when implementing long-tosses into throwing and rehabilitation programs

    Self-Duality in D <= 8-dimensional Euclidean Gravity

    Full text link
    In the context of D-dimensional Euclidean gravity, we define the natural generalisation to D-dimensions of the self-dual Yang-Mills equations, as duality conditions on the curvature 2-form of a Riemannian manifold. Solutions to these self-duality equations are provided by manifolds of SU(2), SU(3), G_2 and Spin(7) holonomy. The equations in eight dimensions are a master set for those in lower dimensions. By considering gauge fields propagating on these self-dual manifolds and embedding the spin connection in the gauge connection, solutions to the D-dimensional equations for self-dual Yang-Mills fields are found. We show that the Yang-Mills action on such manifolds is topologically bounded from below, with the bound saturated precisely when the Yang-Mills field is self-dual. These results have a natural interpretation in supersymmetric string theory.Comment: 9 pages, Latex, factors in eqn. (6) corrected, acknowledgement and reference added, typos fixe

    Nonsingular Black Hole Evaporation and ``Stable'' Remnants

    Get PDF
    We examine the evaporation of two--dimensional black holes, the classical space--times of which are extended geometries, like for example the two--dimensional section of the extremal Reissner--Nordstrom black hole. We find that the evaporation in two particular models proceeds to a stable end--point. This should represent the generic behavior of a certain class of two--dimensional dilaton--gravity models. There are two distinct regimes depending on whether the back--reaction is weak or strong in a certain sense. When the back--reaction is weak, evaporation proceeds via an adiabatic evolution, whereas for strong back--reaction, the decay proceeds in a somewhat surprising manner. Although information loss is inevitable in these models at the semi--classical level, it is rather benign, in that the information is stored in another asymptotic region.Comment: 23 pages, 6 figures, harvmac and epsf, RU-93-12, PUPT-1399, NSF-ITP-93-5

    The non-Abelian gauge theory of matrix big bangs

    Full text link
    We study at the classical and quantum mechanical level the time-dependent Yang-Mills theory that one obtains via the generalisation of discrete light-cone quantisation to singular homogeneous plane waves. The non-Abelian nature of this theory is known to be important for physics near the singularity, at least as far as the number of degrees of freedom is concerned. We will show that the quartic interaction is always subleading as one approaches the singularity and that close enough to t=0 the evolution is driven by the diverging tachyonic mass term. The evolution towards asymptotically flat space-time also reveals some surprising features.Comment: 29 pages, 8 eps figures, v2: minor changes, references added: v3 small typographical changes

    Impact of Indian Total Sanitation Campaign on latrine coverage and use: a cross-sectional study in Orissa three years following programme implementation.

    Get PDF
    BACKGROUND: Faced with a massive shortfall in meeting sanitation targets, some governments have implemented campaigns that use subsidies focused on latrine construction to overcome income constraints and rapidly expand coverage. In settings like rural India where open defecation is common, this may result in sub-optimal compliance (use), thereby continuing to leave the population exposed to human excreta. METHODS: We conducted a cross-sectional study to investigate latrine coverage and use among 20 villages (447 households, 1933 individuals) in Orissa, India where the Government of India's Total Sanitation Campaign had been implemented at least three years previously. We defined coverage as the proportion of households that had a latrine; for use we identified the proportion of households with at least one reported user and among those, the extent of reported use by each member of the household. RESULTS: Mean latrine coverage among the villages was 72% (compared to <10% in comparable villages in the same district where the Total Sanitation Campaign had not yet been implemented), though three of the villages had less than 50% coverage. Among these households with latrines, more than a third (39%) were not being used by any member of the household. Well over a third (37%) of the members of households with latrines reported never defecating in their latrines. Less than half (47%) of the members of such households reported using their latrines at all times for defecation. Combined with the 28% of households that did not have latrines, it appears that most defecation events in these communities are still practiced in the open. CONCLUSION: A large-scale campaign to implement sanitation has achieved substantial gains in latrine coverage in this population. Nevertheless, gaps in coverage and widespread continuation of open defecation will result in continued exposure to human excreta, reducing the potential for health gains

    Process Evaluation of a Dutch Community Intervention to improve Health Related Behaviour in deprived neighbourhoods

    Get PDF
    Objectives: To assess whether a community intervention on health related behaviour in deprived neighbourhoods was delivered as planned and the extent of exposure to the intervention programme. Methods: Data were gathered throughout the intervention period using minutes of meetings, registration forms and a postal questionnaire among residents in intervention and comparison neighbourhoods. Results: Overall, the intervention was delivered according to the key principles of a "community approach", although community participation could have been improved. Neighbourhood coalitions organized more than 50 health related activities in the neighbourhoods over a two-year period. Most activities were directed at attracting attention, providing information, and increasing awareness and knowledge, and at changing behaviours. Programme awareness and programme participation were 24% respectively 3% among residents in the intervention neighbourhoods. Conclusions: The process evaluation indicated that it was feasible to implement a community intervention according to the key principles of the "community approach" in deprived neighbourhoods. However, it is unlikely that the total package of intervention activities had enough strength and sufficient exposure to attain community-wide health behaviour change

    Clinical psychologists’ use of reflection and reflective practice within clinical work

    Get PDF
    Previous research regarding reflective practice has considered the training and development of reflective skills; little attention has been paid to how these are used by clinicians in practice. This study aims to understand how clinical psychologists experience reflection and reflective practice in their day-to-day clinical role. Six practicing clinical psychologists in Singapore were interviewed regarding their experiences. The interviews were analysed using Interpretative Phenomenological Analysis. Participants experienced reflection and reflective practice in many ways. Reflection helped the participants understand themselves better and how they personally impacted their work. Reflection helped in understanding and engaging with clients; it was particularly important for the development of the therapeutic relationship, and when cases felt ‘stuck’. Finally, reflection helped participants understand their professional role as clinicians, and maintain professional and ethical standards. Whilst participants valued reflection and could describe the mechanisms they used to reflect, they struggled to define reflective practice and their own process of reflection. In conclusion, participants were able to describe how using reflection and reflective practice within their clinical work benefited them and their clients. Further investigation into this area is required, particularly focusing on the challenging issue of developing a clearer definition of reflective practice

    Mortality after admission for acute myocardial infarction in Aboriginal and non-Aboriginal people in New South Wales, Australia: a multilevel data linkage study

    Get PDF
    Background - Heart disease is a leading cause of the gap in burden of disease between Aboriginal and non-Aboriginal Australians. Our study investigated short- and long-term mortality after admission for Aboriginal and non-Aboriginal people admitted with acute myocardial infarction (AMI) to public hospitals in New South Wales, Australia, and examined the impact of the hospital of admission on outcomes. Methods - Admission records were linked to mortality records for 60047 patients aged 25–84 years admitted with a diagnosis of AMI between July 2001 and December 2008. Multilevel logistic regression was used to estimate adjusted odds ratios (AOR) for 30- and 365-day all-cause mortality. Results - Aboriginal patients admitted with an AMI were younger than non-Aboriginal patients, and more likely to be admitted to lower volume, remote hospitals without on-site angiography. Adjusting for age, sex, year and hospital, Aboriginal patients had a similar 30-day mortality risk to non-Aboriginal patients (AOR: 1.07; 95% CI 0.83-1.37) but a higher risk of dying within 365 days (AOR: 1.34; 95% CI 1.10-1.63). The latter difference did not persist after adjustment for comorbid conditions (AOR: 1.12; 95% CI 0.91-1.38). Patients admitted to more remote hospitals, those with lower patient volume and those without on-site angiography had increased risk of short and long-term mortality regardless of Aboriginal status. Conclusions - Improving access to larger hospitals and those with specialist cardiac facilities could improve outcomes following AMI for all patients. However, major efforts to boost primary and secondary prevention of AMI are required to reduce the mortality gap between Aboriginal and non-Aboriginal people
    corecore