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Currently, all elite high jumpers use the Fosbury Flop technique with a curved approach. This suggests that the curved approach presents some clear advantage, although there is no general agreement upon the mechanism or the mechanics. This study aimed to determine the characteristics of the approach curve and to investigate how it contributes to the generation of somersault rotation. A simple theoretical model was used to demonstrate that a tightening approach curve would change the inward lean towards the centre of the curve into outwards lean. Three-dimensional video analysis was used to record the performances of two elite male high jumpers in competition. It was found that in each case the radius of the approach curve and the inward lean angle both decreased towards the end of the approach. The amount of outward lean angular velocity generated was shown to be a major proportion of the required somersault angular velocity for a jump. It was concluded that the main advantage of a curved approach was that it resulted in the generation of somersault velocity providing the curve tightened towards the end of the approach. 相似文献
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How money matters for young children's development: parental investment and family processes 总被引：5，自引：0，他引：5
This study used data from the Panel Study of Income Dynamics and its 1997 Child Development Supplement to examine how family income matters for young children's development. The sample included 753 children who were between ages 3 and 5 years in 1997. Two sets of mediating factors were examined that reflect two dominating views in the literature: (1) the investment perspective, and (2) the family process perspective. The study examined how two measures of income (stability and level) were associated with preschool children's developmental outcomes (Woodcock-Johnson [W-J] Achievement Test scores and the Behavior Problem Index [BPI]) through investment and family process pathways. Results supported the hypothesis that distinct mediating mechanisms operate on the association between income and different child outcomes. Much of the association between income and children's W-J scores was mediated by the family's ability to invest in providing a stimulating learning environment. In contrast, family income was associated with children's BPI scores primarily through maternal emotional distress and parenting practices. Level of income was associated with W-J letter-word scores and income stability was associated with W-J applied problem scores and BPI, even after all controls were included in the models. 相似文献
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Jennifer Brown Urban Miriam R. Linver Sara K. Johnson Marisa MacDonnell Lisa M. Chauveron Monica Glina 《Journal of moral education》2018,47(1):104-125
School-based character education (CE) programs provide an opportunity to increase the moral fortitude of adolescents. This study is a preliminary evaluation of Inspire Aspire, a CE program that was implemented with 13- to 14-year-olds in Scotland. A relational developmental systems meta-theoretical approach and person-centered analyses were employed to understand whether teacher implementation variability is associated with student outcomes. The study aimed to: assess variation in program implementation across teachers; assess student poster quality, which served as a youth outcome measure; and, assess the relationship between variations in program implementation and poster quality. Teachers who fully integrated Inspire Aspire with the broader curriculum (as opposed to using it as a standalone program) as well as teachers who made more modifications to Inspire Aspire tended to have students with higher quality posters. This finding stands in contrast to the common narrative regarding evidence-based programs that requires teachers to strictly adhere to program guidelines in order to maintain implementation fidelity. 相似文献
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