An Investigation of Take-Off Impulses in Two Styles of High Jumping

Abstract

The purpose of this study was to compare the impulses exerted at take-off in high jumping using the western-roll style with the impulses exerted at take-off using the straddle style. A force-platform designed to sense forces exerted in three orthogonal directions upon its upper surface was used to obtain data. Some significant differences were found in favor of the western-roll style.     

The longitudinal relationship between generalized self-efficacy and physical activity in school-aged children

Our understanding of the longitudinal relationship between generalized self-efficacy (GSE) and physical activity in children and youth is limited. The purpose of this study was to investigate the effect of GSE towards physical activity on sedentary behaviours and physical activity in school-aged children over time. A total of 2278 nine-year-old children (1120 girls and 1158 boys) were recruited at baseline and followed for seven waves of data collection from 2005 to 2008. All children completed questionnaires at each wave assessing their GSE (adequacy, predilection, and enjoyment), sedentary behaviours, free play, and organized activity. Mixed-effects models were used to estimate changes in physical activity and GSE within individuals over time, controlling for gender and motor ability. The results showed that participation in free play significantly increased over time, whereas organized activity significantly decreased over the same period. Children with high perceived adequacy and predilection had higher free play and organized activity participation relative to other children over time. However, the effect of perceived adequacy diminished over time, while the gaps between groups with different levels of predilection widened over time. While sedentary behaviours were lower over time in children with high predilection, these behaviours were consistently higher in children with high enjoyment. The differences in sedentary behaviours between groups increased over time for both predilection and enjoyment. This study highlights the importance of different components of GSE on physical activity participation. In addition, interventions targeting the enhancement of predilection may facilitate physical activity and reduce sedentary behaviours.     

The effect of change and transformation on academic staff and job satisfaction: A case of a South African University

No institution of higher education in the world can make valid claims that it is immune to the effects of change and transformation. An array of trends such as the massification of higher education, widened access, response to new demands of technology, globalisation, internationalisation, increased accountability, the use of new modes of delivery and materials, as well as dwindling higher education resources, are placing enormous pressure on staff (Green and Hayward, Transforming Higher Education. Phoenix: Oryx Press, 1997). Not only are traditional academic roles changing, but – in certain instances – working conditions have become unfavourable and unsupportive of staff’s efforts to pursue the mission of higher education. The article presents the outcome of a case study that was undertaken in a historically White Afrikaans university to investigate the implications of change and transformation on academic staff. Although the case study was conducted within a localised boundary of space and time of one institution, the authors are of the opinion that enough evidence exists that, given the dominating ruling culture of the apartheid’s regime, to which no university in South Africa was immune, it is most likely that other institutions will relate with the findings of the research. The study was emancipatory in that it sought to inform the university management about how transformation was affecting academics and their job satisfaction and to establish which strategies the University had in place or hoped to put in place to make the environment favourable for change. Academics were also involved in making recommendations on how the areas of dissatisfaction could best be addressed.     

零售业如何从核心扩张

如何明智地开拓新业务 　　1/3是个极为偶然的机会.然后,当零售业的公司在搜寻那些取悦股东与公司利益相关人的增长战略时,许多公司都将赌注押在其核心业务之外的产品服务、市场或商业模式上.贝恩公司对1989～2004年间60多家美国零售业公司近300个试图进入邻近业务的案例进行了分析,发现只有29%的尝试取得了盈利性的增长.而且,只有15%的尝试达到了“积累赌注“,也就是说不仅满足了净现值为正而且实现了收入与利润增长超过5%.……     

Conflict and Its Resolution in Small Groups of One- and Two-Year-Olds

48 1- and 48 2-year-olds were observed in groups of 3 for 25 min on 2 consecutive days, once with ample resources and once with scarce resources. The triads were composed of either 2 girls and a boy or 2 boys and a girl, and duplicate copies of toys were available for half the groups. Their conflicts contained interpersonal features and were more affected by social influences than by the availability of resources. Contrary to expectations, scarcity of resources did not result in increased conflict. In fact, 2-year-olds were more likely to resolve conflict by sharing when toys were scarce. The provision of duplicates decreased the probability of conflict, but many conflicts occurred even when a duplicate was easily accessible. The form of conflict depended on the children's age and the gender composition of the group. Older children and groups dominated by boys, relative to younger children and groups dominated by girls, were less likely to use force and more likely to resolve disputes in prosocial ways. Taken together, these findings provide further evidence for the social nature of conflict in the first few years of life.