1,214 research outputs found

    Phases of the Traditional 505 Test: Between Session and Direction Reliability

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    Change of direction (COD) testing has commonly reported a single total time to quantify performance despite that tests are made up of a number of different phases. No investigation into these phases has been completed, therefore the aim of this study was to examine the reliability between sessions and directions of the different phases of a 505 test. Twenty-one male youth athletes performed the 505 test in both directions on three occasions. Differences between directions and sessions were determined via a T-test and Two-way ANOVA respectively and a significance threshold was set at P ≀ 0.05. All strategy variables show acceptable relative and absolute reliability in both directions between sessions (ICC = 0.73-0.94; CV = 2.3-6.3%) apart from ground contact time (GCT) (ICC = 0.57-0.68, CV = 14.8–22.4%). Significant differences were identified between session one and three for entry time. Significant differences between directions for exit time on day two and for full approach, entry and GCT on day three. The non-dominant turning direction showed lower relative and absolute reliability between session for entry time (ICC = 0.73 vs 0.89; CV = 6.3% vs 3.7%) and GCT (ICC = 0.57 vs 0.68; CV = 14.8% vs 22.4%). Results indicate the phases of a 505 COD test have high relative and absolute reliability between sessions, although turning directions should be considered independently

    Expanded Vandermonde powers and sum rules for the two-dimensional one-component plasma

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    The two-dimensional one-component plasma (2dOCP) is a system of NN mobile particles of the same charge qq on a surface with a neutralising background. The Boltzmann factor of the 2dOCP at temperature TT can be expressed as a Vandermonde determinant to the power Γ=q2/(kBT)\Gamma=q^{2}/(k_B T). Recent advances in the theory of symmetric and anti-symmetric Jack polymonials provide an efficient way to expand this power of the Vandermonde in their monomial basis, allowing the computation of several thermodynamic and structural properties of the 2dOCP for NN values up to 14 and Γ\Gamma equal to 4, 6 and 8. In this work, we explore two applications of this formalism to study the moments of the pair correlation function of the 2dOCP on a sphere, and the distribution of radial linear statistics of the 2dOCP in the plane

    The Deceleration Deficit: A Novel Field-Based Method to Quantify Deceleration During Change of Direction Performance

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    The study investigated the relationship between linear and change of direction (COD) speed performance components and the individual differences between deceleration deficit (DD) and COD deficit (CODD). Thirty-six subjects (mean ±SD: age = 20.3 ± 2.9 years; stature = 175.2 ± 7.7 cm; body mass = 78.0 ± 16.7 kg) completed three trials of a 505 test in both turning directions (dominant (D); non-dominant (ND)) and three 15m linear sprints. DD was calculated via the 15m approach in the 505 test, minus the athlete’s linear 15m sprint time. To compare individuals CODD and DD, z-scores were calculated, and moderate worthwhile changes (MWC) were identified between these deficit z-scores. Significant correlations were identified between linear sprints and 505 time (D: r = 0.71, 0.74; P < 0.01. ND: r = 0.76, 0.75; P < 0.01) for 10m and 15m sprint respectively, and between 505 performance and CODD (D: r = 0.74; P < 0.01. ND: r = 0.77; P < 0.01) and DD (D: r = 0.41, P < 0.05. ND: r = 0.44, P < 0.01). DD was significantly related to CODD (D: r = 0.59; P < 0.01. ND: r = 0.62; P < 0.01); however, 78% of subjects demonstrated differences between these deficit measures greater than an MWC. In conclusion, linear speed has the strongest significant relationship with 505 performance. DD could provide a more isolated construct than CODD which may be related to an athlete’s deceleration capabilities

    Environment and Rural Affairs Monitoring & Modelling Programme - ERAMMP Year 1 Report 16: NRW & ERAMMP monitoring activities review

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    The aim of the Natural Resources Wales (NRW) and other monitoring activities review is to recommend where the key opportunities exist to address evidence gaps, better align activities and reduce duplication. This should not duplicate the intensive work involving more than 40 organisations and over 100 individuals which resulted in the ‘Options for a New Integrated Natural Resource Monitoring Framework for Wales’ 1 review which identified more than 180 monitoring schemes and provided 6 independent reviews of new opportunities for the monitoring community

    Strangeness Enhancement in p-A Collisions: Consequences for the Interpretation of Strangeness Production in A-A Collisions

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    Published measurements of semi-inclusive Lambda production in p-Au collisions at the AGS are used to estimate the yields of singly strange hadrons in nucleus-nucleus A-A collisions. Results of a described extrapolation technique are shown and compared to measurements of K+ production in Si-Al, Si-Au, and Au-Au collisions at the AGS and net Lambda production in Su-Su, S-Ag, Pb-Pb, and inclusive p-A collisions at the SPS. The extrapolations can account for more than 75% of the measured strange particle yields in all of the studied systems except for very central Au-Au collisions at the AGS where RQMD comparisons suggest large re-scattering contributions.Comment: 9 pages, 4 figure

    Jack superpolynomials with negative fractional parameter: clustering properties and super-Virasoro ideals

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    The Jack polynomials P_\lambda^{(\alpha)} at \alpha=-(k+1)/(r-1) indexed by certain (k,r,N)-admissible partitions are known to span an ideal I^{(k,r)}_N of the space of symmetric functions in N variables. The ideal I^{(k,r)}_N is invariant under the action of certain differential operators which include half the Virasoro algebra. Moreover, the Jack polynomials in I^{(k,r)}_N admit clusters of size at most k: they vanish when k+1 of their variables are identified, and they do not vanish when only k of them are identified. We generalize most of these properties to superspace using orthogonal eigenfunctions of the supersymmetric extension of the trigonometric Calogero-Moser-Sutherland model known as Jack superpolynomials. In particular, we show that the Jack superpolynomials P_{\Lambda}^{(\alpha)} at \alpha=-(k+1)/(r-1) indexed by certain (k,r,N)-admissible superpartitions span an ideal {\mathcal I}^{(k,r)}_N of the space of symmetric polynomials in N commuting variables and N anticommuting variables. We prove that the ideal {\mathcal I}^{(k,r)}_N is stable with respect to the action of the negative-half of the super-Virasoro algebra. In addition, we show that the Jack superpolynomials in {\mathcal I}^{(k,r)}_N vanish when k+1 of their commuting variables are equal, and conjecture that they do not vanish when only k of them are identified. This allows us to conclude that the standard Jack polynomials with prescribed symmetry should satisfy similar clustering properties. Finally, we conjecture that the elements of {\mathcal I}^{(k,2)}_N provide a basis for the subspace of symmetric superpolynomials in N variables that vanish when k+1 commuting variables are set equal to each other.Comment: 36 pages; the main changes in v2 are : 1) in the introduction, we present exceptions to an often made statement concerning the clustering property of the ordinary Jack polynomials for (k,r,N)-admissible partitions (see Footnote 2); 2) Conjecture 14 is substantiated with the extensive computational evidence presented in the new appendix C; 3) the various tests supporting Conjecture 16 are reporte

    Problematising parent–professional partnerships in education

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    The value of, and need for, parent–professional partnerships is an unchallenged mantra within policy relating to ‘special educational needs’. In spite of this, partnerships continue to be experienced as problematic by both parents and professionals. This paper brings together the different perspectives of two disability researchers: one a parent of a disabled child while the other was a teacher for 20 years of children with the label autism. The paper deconstructs the concept of partnership and then, drawing on the expertise of parents, suggests how enabling and empowering parent–professional relationships might be achieved

    Problematising parent–professional partnerships in education

    Get PDF
    The value of, and need for, parent–professional partnerships is an unchallenged mantra within policy relating to ‘special educational needs’. In spite of this, partnerships continue to be experienced as problematic by both parents and professionals. This paper brings together the different perspectives of two disability researchers: one a parent of a disabled child while the other was a teacher for 20 years of children with the label autism. The paper deconstructs the concept of partnership and then, drawing on the expertise of parents, suggests how enabling and empowering parent–professional relationships might be achieved

    Reliability of the tuck jump injury risk screening assessment in elite male youth soccer players

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    Altered neuromuscular control has been suggested as a mechanism for injury in soccer players. Ligamentous injuries most often occur during dynamic movements, such as decelerations from jump-landing maneuvers where high risk movement patterns are present. The assessment of kinematic variables during jump-landing tasks as part of a pre-participation screen is useful in the identification of injury risk. An example of a field-based screening tool is the repeated tuck jump assessment. The purpose of this study was to analyze the within-subject variation of the tuck jump screening assessment in elite male youth soccer players. 25 pre and 25 post-peak height velocity (PHV) elite male youth soccer players from the academy of a professional English soccer club completed the assessment. A test, re-test design was used to explore the within-subject inter-session reliability. Technique was graded retrospectively against the 10-point criteria set out in the screening protocol using two-dimensional video cameras. The typical error range reported for tuck jump total score (0.90 – 1.01 in pre and post-PHV players respectively) was considered acceptable. When each criteria was analyzed individually, Kappa coefficient determined that knee valgus was the only criterion to reach substantial agreement across the two test sessions for both groups. The results of this study suggest that although tuck jump total score may be reliably assessed in elite male youth soccer players, caution should be applied in solely interpreting the composite score due to the high within-subject variation in a number of the individual criteria. Knee valgus may be reliably used to screen elite youth male soccer players for this plyometric technique error and for test, re-test comparison

    Eigenvalue Problem in Two Dimensions for an Irregular Boundary II: Neumann Condition

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    We formulate a systematic elegant perturbative scheme for determining the eigenvalues of the Helmholtz equation (\bigtriangledown^{2} + k^{2}){\psi} = 0 in two dimensions when the normal derivative of {\psi} vanishes on an irregular closed curve. Unique feature of this method, unlike other perturbation schemes, is that it does not require a separate formalism to treat degeneracies. Degenerate states are handled equally elegantly as the non-degenerate ones. A real parameter, extracted from the parameters defining the irregular boundary, serves as a perturbation parameter in this scheme as opposed to earlier schemes where the perturbation parameter is an artificial one. The efficacy of the proposed scheme is gauged by calculating the eigenvalues for elliptical and supercircular boundaries and comparing with the results obtained numerically. We also present a simple and interesting semi-empirical formula, determining the eigenspectrum of the 2D Helmholtz equation with the Dirichlet or the Neumann condition for a supercircular boundary. A comparison of the eigenspectrum for several low-lying modes obtained by employing the formula with the corresponding numerical estimates shows good agreement for a wide range of the supercircular exponent.Comment: 26 pages, 12 figure
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