Differences in the utilisation of active power in squat and countermovement jumps

The aim of this article was to understand how active power is used in squat and countermovement jumps. A simple empirical model comprising a mass, a spring, an active element and a damper, together with an optimisation principle, was used to identify the mechanical factors that maximise performance of jumps without countermovement (squat jumps, SJ) and with countermovement (CMJ). Twelve amateur volleyball players performed SJ from two initial positions and CMJ with two degrees of counterbalancing, while kinematic data were collected (jump height, push-off duration and position of the centre of mass). The model adjusted well to real data of SJ through all the impulse phase, and slightly less adequately at the end of this phase for CMJ. Nevertheless, it provides a satisfactory explanation for the generation and utilisation of active power for both type of jumps. On average, the estimated power of the active elements, the spring, and the damper were greater in the SJ. Based upon the result obtained with this model, we suggest that active power is best evaluated with SJ. The reason for this is that, during this kind of jump, the elements associated with the damper consume much of the energy produced by the active elements. The participation of the elements that consume the energy generated by the active elements is less in CMJ than in SJ, allowing for a better utilisation of this energy. In this way it is possible to achieve a better performance in CMJ with less active power.     

Editorial statement

Grounded in the interdisciplinary educational work of Cultural Studies, this paper examines the pedagogical potentials of narrative and performance for the teaching of writing as a mode of public discourse. Guided to address a wide readership, students engage in critical communication aimed at linking self inquiry and narrative discourse to the contextual analysis of the social. Drawing on research findings derived from the undergraduate teaching of cultural criticism as a genre of public writing at Lingnan University, Hong Kong, we look at how educational drama mediates the work of narrative and performative acts involving the young learner-writers and contributes to the shaping of a dialogic mode of address and communication, thus articulating the process and impact of writing to the public-oriented discourse in Cultural Studies education. In light of such acts in critical discourse and imagination targeted at the potential reader, we show how the young writers' own engagement with critical thinking and communication are opened up by drama-in-education adopted in the class, and argue how, in this sense, both writing and its learning process become effective stages in the making of the kind of cultural criticism we want to help students to learn.     

村干部不同领导方式对村民自治绩效的影响

将村干部的领导方式分为权威型、民主型、放任型三种类型,从经济绩效、政治绩效(分为民主管理绩效、公民参与绩效)、社会绩效、公共产品与服务供给绩效4个方面衡量村民自治绩效,根据对多个省份16个村庄的问卷调查,分析村干部领导方式对村民自治绩效的影响。分析表明,权威型领导方式与社会绩效以及公民参与绩效显著正相关,民主型领导方式与经济绩效、民主管理绩效、公民参与绩效、社会绩效、公共供给绩效显著正相关,而其他变量之间的关系不显著。因此,村干部民主型领导方式我国农村治理中具有普遍的适用性,权威型的领导方式也有一定的适应性,而放任型的领导方式是不适用的。村干部应灵活运用权威型与民主型领导方法,避免放任型领导风格和方式。     

预冷对运动员高温环境下运动表现的影响研究

很多研究表明高温环境对运动员的运动表现是有害的,如对氧运输能力、心血管功能以及内环境和离子平衡都会造成不良影响。体育科研人员发现预冷处理能够改善运动员在高温环境下的运动表现。预冷处理是指在训练前或比赛前,预先将运动员身体做降温处理,通过降低核心体温、改善心血管压力、减少代谢失调等来调整各项生理指标,提升运动员的热贮存能力,延缓运动疲劳产生,使运动员在训练或比赛时有良好的运动表现。     

2019年篮联世界杯广州赛区小组赛对中国队的启示

2019年国际篮联篮球世界杯在中国圆满举行,广州作为分赛场,承接了西班牙、波多黎各、突尼斯以及伊朗四支代表队的小组比赛6场。通过对广州赛区四支队伍在小组赛中的表现技术进行分析,并对比中国队在本次赛事中的表现,发现中国男篮在备赛与参赛阶段,存在大赛目标不清晰,心理训练与细节训练不足,教练团队执教水平不稳定,篮球基本功不扎实等一系列问题,反映出我国篮球的发展正处于困境。系统地分析广州小组赛中四支队伍的赛况,并与中国队做出对比,有针对性地提出建议,为中国篮球的发展提供参考。     

宽带薪酬的适用性分析

宽带薪酬作为一种新型的薪酬模式备受国内企业关注。在阐明宽带薪酬内涵及其现实意义的基础上,对宽带薪酬模式的适用性进行了分析,指出扁平化的组织结构、科学的绩效考核体系、强调公平的企业文化以及完善的激励机制是企业实施宽带薪酬所应具备的基本条件。     

从生存论的角度透视英语学习动机

从生存角度看,英语是社会生存发展的产物,是全球性的语言。英语学习的个人动机虽不同,却都与生存紧密相关,都是为了更好地生存。     

企业技术联盟绩效评价体系的比较和发展趋势分析

对于企业技术联盟而言,其绩效的测度一直引起人们的关注,但是不论是在理论上还是实践中都存在着诸多的分歧和争论。大量研究活动表明,企业技术联盟的绩效评价存在一定的复杂性。本文比较和评述了现有的企业技术联盟绩效评价体系,指出了其存在的局限性;并阐述了其发展趋势,包括:投入和产出的无形化;评价指标的非财务化;评价过程的动态化;评价标准的多样化;定量与定性相结合。     

高校人才集聚绩效评价方法探析:集聚指数的编制与应用

优秀人才的集聚是高校核心竞争力提升的首要前提,而如何考量高校人才集聚的绩效成为亟待解决的难题。本研究运用统计指数相关方法编制了高校人才集聚指数作为绩效评价的一种方法,并进一步选择位于东北、西北、中部、东部和东南的5所“985”高校,对其2000年以来人才集聚指数进行测算,通过分析测算结果发现五所高校的人才流动均呈逐步优化的发展态势,且发展态势相对稳健,但高校间人才集聚绩效存在一定差异,而差异幅度在一段时间内表现得相对稳定。