8,958 research outputs found

    Certified Athletic Trainers\u27 Abilities to Identify and Refer Athletes with Psychological Symptoms

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    This study\u27s purpose was to expand the literature based in the area of psychology of injury by assessing certified athletic trainers\u27 (ATs\u27) skills in symptom identification, intended course of action, and intervention identification with athletes experiencing psychological distress. Using a web-based survey protocol, data were collected from 326 (191 female and 132 male) ATs using three case vignettes. AT responses were compared to a panel of experts in psychology of injury and assessed for accuracy. Results indicated that ATs demonstrated high accuracy in symptom identification and making referral decision, but struggled in identifying appropriate interventions for athletes. Stepwise regression analyses revealed that as ATs reported more specific coursework in sport psychology, they were able to more accurately identify symptoms across all cases (t = 3.01, p \u3c .01) and those ATs with more experience reported lower scores in accurately choosing a course of action (t = -2.25, p \u3c .05). Overall, the results provide evidence of ATs\u27 abilities to apply their knowledge of sport psychology within the athletic training realm while also raising some important questions regarding the structure of existing sport psychology coursework. Findings may emphasize the inclusion of coursework focusing more heavily on applied areas of sport psychology in the training of ATs

    Effects of Hyperbolic Rotation in Minkowski Space on the Modeling of Plasma Accelerators in a Lorentz Boosted Frame

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    Laser driven plasma accelerators promise much shorter particle accelerators but their development requires detailed simulations that challenge or exceed current capabilities. We report the first direct simulations of stages up to 1 TeV from simulations using a Lorentz boosted calculation frame resulting in a million times speedup, thanks to a frame boost as high as gamma=1300. Effects of the hyperbolic rotation in Minkowski space resulting from the frame boost on the laser propagation in the plasma is shown to be key in the mitigation of a numerical instability that was limiting previous attempts

    Alien Registration- Farnsworth, Mary L. (Bath, Sagadahoc County)

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    https://digitalmaine.com/alien_docs/9522/thumbnail.jp

    Modeling laser wakefield accelerators in a Lorentz boosted frame

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    Modeling of laser-plasma wakefield accelerators in an optimal frame of reference \cite{VayPRL07} is shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups requires mitigation of a high-frequency instability that otherwise limits effectiveness in addition to solutions for handling data input and output in a relativistically boosted frame of reference. The observed high-frequency instability is mitigated using methods including an electromagnetic solver with tunable coefficients, its extension to accomodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is shown that choosing the frame of the wake as the frame of reference allows for higher levels of filtering and damping than is possible in other frames for the same accuracy. Detailed testing also revealed serendipitously the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion, thus indicating that the observed instability may not be due primarily to Numerical Cerenkov as has been conjectured. The techniques developed for Cerenkov mitigation prove nonetheless to be very efficient at controlling the instability. Using these techniques, agreement at the percentage level is demonstrated between simulations using different frames of reference, with speedups reaching two orders of magnitude for a 0.1 GeV class stages. The method then allows direct and efficient full-scale modeling of deeply depleted laser-plasma stages of 10 GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively

    Athletic Trainers\u27 Skills in Identifying and Managing Athletes Experiencing Psychological Distress

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    Context Athletic trainers (ATs) commonly use psychological skills during sport rehabilitation. However, little is known about their ability to accurately implement these skills. Objective To assess ATs\u27 skills in identifying psychological symptoms, selecting appropriate strategies, and making referral decisions for athletes experiencing various degrees of psychological distress. Design Cross-sectional study. Setting Participants were recruited using the National Athletic Trainers\u27 Association professional member database. Patients or Other Participants Of the 2998 ATs who were selected randomly, 494 (16.5%) partially completed the questionnaire and 326 (10.9%) completed the entire survey (mean age = 34.7 ± 10.8 years, mean years of experience = 11.3 ± 9.9). Main Outcome Measure(s) Using the Web-based questionnaire created for this study, we collected ATs\u27 demographic information and assessed their perceptions about responsibilities as ATs, psychosocial competencies, training in sport psychology, and referral behaviors. Additionally, respondents were asked to identify symptoms, match psychological strategies (eg, goal setting, imagery, progressive muscle relaxation), and make referral decisions for athletes in 3 case vignettes. Results The ATs demonstrated high accuracy in identifying symptoms and making referral decisions but struggled in selecting appropriate psychosocial strategies for athletes. Stepwise regression analyses revealed that ATs who had had specific coursework in sport psychology were able to more accurately identify symptoms (t = 3.01, P \u3c .01), and those ATs with more experience reported lower accuracy scores for their intended course of action (t  =  −2.25, P \u3c .05). Conclusions Our analogue research design provided new insights into ATs\u27 knowledge and use of sport psychology in practice. The results highlighted the importance of coursework focusing on applied areas of sport psychology in the training of ATs

    Speeding up simulations of relativistic systems using an optimal boosted frame

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    It can be computationally advantageous to perform computer simulations in a Lorentz boosted frame for a certain class of systems. However, even if the computer model relies on a covariant set of equations, it has been pointed out that algorithmic difficulties related to discretization errors may have to be overcome in order to take full advantage of the potential speedup. We summarize the findings, the difficulties and their solutions, and show that the technique enables simulations important to several areas of accelerator physics that are otherwise problematic, including self-consistent modeling in three-dimensions of laser wakefield accelerator stages at energies of 10 GeV and above.Comment: To be published in the proceedings of DPF-2009, Detroit, MI, July 2009, eConf C09072

    Establishing the Breeding Provenance of a Temperate-Wintering North American Passerine, the Golden-Crowned Sparrow, Using Light-Level Geolocation

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    The migratory biology and connectivity of passerines remains poorly known, even for those that move primarily within the temperate zone. We used light-level geolocators to describe the migratory geography of a North American temperate migrant passerine. From February to March of 2010, we attached geolocator tags to 33 Golden-crowned Sparrows (Zonotrichia atricapilla) wintering on the central coast of California, USA, and recovered four tags the following winter (October to December 2010). We used a Bayesian state-space model to estimate the most likely breeding locations. All four birds spent the breeding season on the coast of the Gulf of Alaska. These locations spanned approximately 1200 kilometers, and none of the individuals bred in the same location. Speed of migration was nearly twice as fast during spring than fall. The return rate of birds tagged the previous season (33%) was similar to that of control birds (39%), but comparing return rates was complicated because 7 of 11 returning birds had lost their tags. For birds that we recaptured before spring migration, we found no significant difference in mass change between tagged and control birds. Our results provide insight into the previously-unknown breeding provenance of a wintering population of Golden-crowned Sparrows and provide more evidence of the contributions that light-level geolocation can make to our understanding of the migratory geography of small passerines

    Structure and dynamics of Oxide Melts and Glasses : a view from multinuclear and high temperature NMR

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    Solid State Nuclear Magnetic Resonance (NMR) experiments allow characterizing the local structure and dynamics of oxide glasses and melts. Thanks to the development of new experiments, it now becomes possible to evidence not only the details of the coordination state of the network formers of glasses but also to characterize the nature of polyatomic molecular motifs extending over several chemical bonds. We present results involving 31P homonuclear experiments that allow description of groups of up to three phosphate units and 27Al/17O heteronuclear that allows evidencing μ3 oxygen bridges in aluminate glasses and rediscussion of the structure of high temperature melts.Comment: Journal of Non-Crystalline Solids (2007) in press; Also available online at: http://crmht.cnrs-orleans.fr/Intranet/Publications/?id=207
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