6,944 research outputs found

    Effects of physical efforts on injury in elite soccer

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    In this study, the influence of physical efforts on occurrence of match injury in a professional soccer club was investigated. Computerised motion-analysis was used to measure the physical efforts of players during 10 injury situations. Total distance and those covered at different movement intensities were measured across the 5-min period preceding injury. If the final run preceding injury involved a high-intensity action (HIA), the distance, duration and speed of the effort and the recovery time between this and the penultimate HIA were measured. To determine the influence of these physical efforts, the results were compared to a normative profile for players computed from data across 5 games for the same variables; habitual distances covered over a 5-min period and characteristics of and recovery time between HIA. Compared to the normative profile, no differences were reported in physical characteristics during the period leading up to injury or for HIA although the latter were substantially higher in intensity (duration and distance). A lower than normal recovery time between HIA prior to injury was observed (35.6±16.8 s vs. 98.8±17.5 s, p=0.003). Within the limitations of the small sample, these findings may aid in further understanding injury and physical performance in elite soccer

    The L-/C-band feed design for the DSS 14 70-meter antenna (Phobos mission)

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    A dual-frequency (1.668 and 5.01 GHz) feed was designed for the Deep Space Station (DSS) 14 70-m antenna to support the Soviet Phobos Mission. This antenna system was capable of supporting telemetry, two-way Doppler, and very long baseline interferometry (VLBI). VLBI and two-way Doppler information on the Phobos spacecraft was acquired with this antenna in 1989

    Engineering calculations for communications satellite systems planning

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    The final phase of a satellite synthesis project is described. Several methods for generating satellite positionings with improved aggregate carrier to interference characteristics were studied. Two general methods for modifying required separation values are presented. Also, two methods for improving aggregate carrier to interference (C/I) performance of given satellite synthesis solutions are presented. A perturbation of the World Administrative Radio Conference (WARC) synthesis is presented

    A New Interpolation Formula

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    113. A new interpolation If we wish to interpolate values of a function between two given values y1, and y2, we may employ a polynomial in x1. When the only conditions to be satisfied are that the function take the value y1 when x=l, and the value y2 when x=2, the polynomial of minimum degree is of the form a0+a1 (x-1). Interpolation by means of this polynomial is that ordinarily employed when using trigonometric and logarithmic tables, and is spoken of as interpolation by first differences. If, however, additional conditions are imposed the degree of the polynomial will increase one unit for each condition. For example, if the interpolated values between y1 and y2 are dependent upon the conditions that the function takes the value y0 when x=0, and the value y3 when x=3, then the interpolation polynomial is of the form a0+a1 (x-1) + a2 (x-1)2 + a3 (x-1)3

    On the Summation Σx^n

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    The symbol Σxn will be used to denote the sum of the n th powers of the first x positive integers, that is, ln + 2n + 3n +... +xn, n integral. It is well known that this sum is equivalent to a polynomial of degree (n+l), having no constant term

    Two Theorems on Annuities

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    In each of the special cases h + k = n - 1, and n annual payments are made. The values of h and k are so chosen that the present comes at the desired point - for the amount of an annuity at the time of the last payment; for the present value of an annuity one year before the first payment; for the amount of an annuity-due one year after the last payment; for the present value of an annuity-due at the time of the first payment; and for the present value of a deferred annuity r + 1 years before the first payment
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