851 research outputs found

    The illusion of competency versus the desirability of expertise: Seeking a common standard for support professions in sport

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    In this paper we examine and challenge the competency-based models which currently dominate accreditation and development systems in sport support disciplines, largely the sciences and coaching. Through consideration of exemplar shortcomings, the limitations of competency-based systems are presented as failing to cater for the complexity of decision making and the need for proactive experimentation essential to effective practice. To provide a better fit with the challenges of the various disciplines in their work with performers, an alternative approach is presented which focuses on the promotion, evaluation and elaboration of expertise. Such an approach resonates with important characteristics of professions, whilst also providing for the essential ‘shades of grey’ inherent in work with human participants. Key differences between the approaches are considered through exemplars of evaluation processes. The expertise-focused method, although inherently more complex, is seen as offering a less ambiguous and more positive route, both through more accurate representation of essential professional competence and through facilitation of future growth in proficiency and evolution of expertise in practice. Examples from the literature are also presented, offering further support for the practicalities of this approach

    Magnetic field independence of the spin gap in YBa_2Cu_3O_{7-delta}

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    We report, for magnetic fields of 0, 8.8, and 14.8 Tesla, measurements of the temperature dependent ^{63}Cu NMR spin lattice relaxation rate for near optimally doped YBa_2Cu_3O_{7-delta}, near and above T_c. In sharp contrast with previous work we find no magnetic field dependence. We discuss experimental issues arising in measurements of this required precision, and implications of the experiment regarding issues including the spin or pseudo gap.Comment: 4 pages, 3 figures, as accepted for publication in Physical Review Letter

    The effect of nose geometry on the aerothermodynamic environment of shuttle entry configurations

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    The effect was studied of nose geometry on the transition criteria for the windward boundary layer, on the extent of separation, on the heat transfer perturbation due to the canopy, and on the surface pressure and the heat transfer in the separated region. The data for each of these problems is analyzed. A literature review that concentrates on separation and the leeward flow-field is presented

    Blaming Bill Gates AGAIN! Misuse, overuse and misunderstanding of performance data in sport

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    Recently in Sport, Education and Society, Williams and Manley (2014) argued against the heavy reliance on technology in professional Rugby Union and elite sport in general. In summary, technology is presented as an elitist, ‘gold standard’ villain that management and coaches use to exert control and by which players lose autonomy, identity, motivation, social interactions and expertise. In this article we suggest that the sociological interpretations and implications offered by Williams and Manley may be somewhat limited when viewed in isolation. In doing so, we identify some core methodological issues in Williams and Manley’s study and critically consider important arguments for utilising technology; notably, to inform coach decision making and generate player empowerment. Secondly, we present a different, yet perhaps equally concerning, practice-oriented interpretation of the same results but from alternative coaching and expertise literature. Accordingly, we suggest that Williams and Manley have perhaps raised their alarm prematurely, inappropriately and on somewhat shaky foundations. We also hope to stimulate others to consider contrary positions, or at least to think about this topic in greater detail. More specifically, we encourage coaches and academics to think carefully about what technology is employed, how and why, and then the means by which these decisions are discussed with and, preferably, sold to players. Certainly, technology can significantly enhance coach decision making and practice, while also helping players to optimise their focus, empowerment and independence in knowing how to achieve their personal and collective goals

    The Superconducting Condensation Energy and an Antiferromagnetic Exchange Based Pairing Mechanism

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    For the traditional low T_c superconductors, the superconducting condensation energy is proportional to the change in energy of the ionic lattice between the normal and superconducting state, providing a clear link between pairing and the electron-ion interaction. Here, for the t-J model, we discuss an analogous relationship between the superconducting condensation energy and the change in the exchange energy between the normal and superconducting states. We point out the possibility of measuring this using neutron scattering and note that such a measurement, while certainly difficult, could provide important evidence for an exchange interaction-based pairing mechanism.Comment: Replaced with revised versio

    The Influence of Magnetic Imperfections on the Low Temperature Properties of D-wave Superconductors

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    We consider the influence of planar ``magnetic" imperfections which destroy the local magnetic order, such as Zn impurities or Cu2+Cu^{2+} vacancies, on the low temperature properties of the cuprate superconductors. In the unitary limit, at low temperatures, for a dx2y2d_{x^2-y^2} pairing state such imperfections produce low energy quasiparticles with an anistropic spectrum in the vicinity of the nodes. We find that for the La2xSrxCuO4La_{2-x}Sr_xCuO_4 system, one is in the {\em quasi-one-dimensional} regime of quasiparticle scattering, discussed recently by Altshuler, Balatsky, and Rosengren, for impurity concentrations in excess of 0.16%\sim 0.16\% whereas YBCO7_7 appears likely to be in the true 2D scattering regime for Zn concentrations less than 1.6%1.6\%. We show the neutron scattering results of Mason et al. \cite{Aeppli} on La1.86Sr0.14CuO4La_{1.86}Sr_{0.14}CuO_4 provide strong evidence for ``dirty d-wave" superconductivity in their samples. We obtain simple expressions for the dynamic spin susceptibility and 63Cu^{63}Cu spin-lattice relaxation time, 63T1^{63}T_1, in the superconducting state.Comment: 10 pages; revtex; Los Alamos preprint LA-UR-94-53

    Integration of professional judgement and decision-making in high-level adventure sports coaching practice

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    This study examined the integration of professional judgement and decision-making processes in adventure sports coaching. The study utilised a thematic analysis approach to investigate the decision-making practices of a sample of high-level adventure sports coaches over a series of sessions. Results revealed that, in order to make judgements and decisions in practice, expert coaches employ a range of practical and pedagogic management strategies to create and opportunistically use time for decision-making. These approaches include span of control and time management strategies to facilitate the decision-making process regarding risk management, venue selection, aims, objectives, session content, and differentiation of the coaching process. The implication for coaches, coach education, and accreditation is the recognition and training of the approaches that“create time” for the judgements in practice, namely“creating space to think”. The paper concludes by offering a template for a more expertise-focused progression in adventure sports coachin

    The Superconducting Instabilities of the non half-filled Hubbard Model in Two Dimensions

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    The problem of weakly correlated electrons on a square lattice is formulated in terms of one-loop renormalization group. Starting from the action for the entire Brillouin zone (and not with a low-energy effective action) we reduce successively the cutoff Λ\Lambda about the Fermi surface and follow the renormalization of the coupling UU as a function of three energy-momenta. We calculate the intrinsic scale TcoT_{co} where the renormalization group flow crosses over from the regime (Λ>Tco\Lambda > T_{co}) where the electron-electron (e-e) and electron-hole (e-h) terms are equally important to the regime (Λ<Tco\Lambda < T_{co}) where only the e-e term plays a role. In the low energy regime only the pairing interaction VV is marginally relevant, containing contributions from all renormalization group steps of the regime Λ>Tco\Lambda > T_{co}. After diagonalization of VΛ=TcoV_{\Lambda =T_{co}}, we identify its most attractive eigenvalue λmin\lambda _{\min}. At low filling, λmin\lambda _{\min} corresponds to the B2B_2 representation (dxyd_{xy} symmetry), while near half filling the strongest attraction occurs in the B1B_1 representation (dx2y2d_{x^2-y^2} symmetry). In the direction of the van Hove singularities, the order parameter shows peaks with increasing strength as one approaches half filling. Using the form of pairing and the structure of the renormalization group equations in the low energy regime, we give our interpretation of ARPES experiments trying to determine the symmetry of the order parameter in the Bi2212 high-TcT_{c} compound.Comment: 24 pages (RevTeX) + 11 figures (the tex file appeared incomplete

    Electronic states on a twin boundary of a d-wave superconductor

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    We show that an induced ss-wave harmonic in the superconducting gap of an orthorhombic dx2y2d_{x^2-y^2} superconductor strongly affects the excitation spectrum near a twinning plane. In particular, it yields bound states of zero energy with areal density proportional to the relative weight of the ss-wave component. An unusual scattering process responsible for the thermal conductivity across the twin boundary at low temperatures is also identified.Comment: 4 pages, ReVTEX, 2 PS-figure
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