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The displacement of the golf ball struck by a driving club is affected by several player characteristics and equipment parameters and their interrelationships. Some modelling and simulation studies have shown a relationship between shaft length and clubhead speed, supported by a few experimental studies. The aim of the present study was to examine the relationship between driver length and ball launch conditions in an indoor test facility using a ball launch monitor. Nine males considered to be skilled golfers participated in the study. Four driving clubs of total length 117, 119, 124, and 132 cm were assembled from commercially available components and were used to strike golf shots while initial ball velocity, backspin rate, and launch angles were measured. Statistical analysis identified a significant difference in initial launch speed due to club length, a significant difference between participants, but no difference between the trials for a given golfer. A positive trend was noted between backspin and launch angle for all four clubs, and significant inverse associations between initial launch speed and backspin rate and launch angle. However, the combined launch conditions associated with increasing length were not considered optimal, with uncontrolled swingweight and moment of inertia effects considered to be limiting factors. 相似文献
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Infants with 0-3 Apgar scores at 1 minute had significantly lower 8-month mental and motor scores than infants with 7-10 scores and significantly lower mental but not motor scores than infants with 4-6 Apgar scores. Correlations indicated significant relationships (independent of birth weight) between Apgar scores and Bayley mental and motor scores for random, Colored Portuguese, and total samples but not for Negroes and whites. Results demonstrated a significant difference in Apgar scores by 8-month classifications with significantly lower scores for children classified as abnormal, and by longevity with significantly lower scores for neonates who died within 2 days. 相似文献
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Mary A. Anderson Frank Bowles C. O. Taiwo Jan D. Beckmann L. J. Lewis James R. Liesch Godfrey N. Brown H. L. Elvin Shib K. Mitra Richard F. Behrendt Graeme Kemelfield Hugh W. R. Hawes W. A. Dodd A. L. Tibawi 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1971,17(2):220-251
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A S Weiner 《Child development》1975,46(4):998-1000
A backward-masking procedure was used to measure the rate of visual information processing in 8- and 10-year-old reflective and impulsive children. The test stimulus (TS) and the masking stimulus (MS) which followed it were presented tachistoscopially. The subject's information-processing threshold was defined as the next highest TS-MS interval above the interval where at least 3 of the 4 TSs were incorrectly identified. Reflective children were significantly faster than impulsive children at processing information. This finding was related to research indicating that reflective and impulsive children employ similar cognitive strategies; it was suggested that performance differences between these children might be related to reflective children employing their strategies with more adequate information. 相似文献