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991.
Psychosocial factors that could be used as predictive indicators for adjustment of 4-year-old children whose mothers had used amphetamine during pregnancy were studied by means of simple and multivariate correlation analyses. The following statistically significant correlations were found: Length of maternal alcohol and drug abuse during pregnancy was correlated negatively with the child's adjustment as were numbers of paternal criminal convictions, number of stress factors of the mother, and number of earlier children born to the mother. Paternal criminality was associated with the outcome, regardless of amount of contact between father and child. 相似文献
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One of the tests used to evaluate the performance of sports surfaces measures the peak deceleration of a rigid mass during
contact with the surface, after being dropped from a set height. It is widely used and is included in a number of international
standards.
The test was carried out using two drop heights on four different designs of artificial cricket pitch, with a full set of
acceleration data being collected over the duration of impact. These data were then integrated twice with respect to time
to produce velocity and displacement information. Oblique impacts of cricket balls were also carried out and analysed using
a high-speed video system to evaluate the playing performance of each pitch design.
It was found that, although the pitches gave quite different readings of peak deceleration, they produced similar values for
coefficient of restitution and were therefore considered to ‘play’ in a very similar way. This was due to a high peak deceleration
reading being accompanied by a short contact time and low peak deceleration being accompanied by a long contact time, meaning
that the change in momentum was similar in both cases. It was concluded that for accelerometer tests to be useful, all the
acceleration-time data should be analysed, rather than the peak value alone. 相似文献
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Biomechanical differences in soccer kicking with the preferred and the non-preferred leg 总被引：2，自引：2，他引：0
The aims of this study were to examine the release speed of the ball in maximal instep kicking with the preferred and the non-preferred leg and to relate ball speed to biomechanical differences observed during the kicking action. Seven skilled soccer players performed maximal speed place kicks with the preferred and the non-preferred leg; their movements were filmed at 400 Hz. The inter-segmental kinematics and kinetics were derived. A coefficient of restitution between the foot and the ball was calculated and rate of force development in the hip flexors and the knee extensors was measured using a Kin-Com dynamometer. Higher ball speeds were achieved with the preferred leg as a result of the higher foot speed and coefficient of restitution at the time of impact compared with the non-preferred leg. These higher foot speeds were caused by a greater amount of work on the shank originating from the angular velocity of the thigh. No differences were found in muscle moments or rate of force development. We conclude that the difference in maximal ball speed between the preferred and the non-preferred leg is caused by a better inter-segmental motion pattern and a transfer of velocity from the foot to the ball when kicking with the preferred leg. 相似文献
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