Effect of different loading conditions on running mechanics at different velocities     

Germán Carretero-Navarro  Doménico Cherubini  Wolfgang Taube 《European Journal of Sport Science》2019,19(5):595-602

Weighted vests are widely used to improve running economy and performance. However, it is not well-studied how running mechanics are adapted to counteract the higher peak vertical ground reaction forces (Fpeak) while running with such a device. Therefore, the present study aimed to investigate the effects of different loading conditions on running mechanics at different velocities. Thirteen subjects participated in two separate sessions one week apart. In the first session, maximal aerobic speed (MAS) was determined through a maximal incremental running test while in the second session, they were instructed to run during one minute under different loading (0%, +10% and +20% of body mass [BM]) and velocity (60%, 80% and 100% of MAS) conditions in a random order. Spatiotemporal data were recorded and then running mechanics modelled using the spring-mass model. The main results indicated that vertical and leg stiffness (Kvert and Kleg, respectively) were increased (P?P?>?.05) when load was changed. At the same time, alterations of the running kinematics were observed such as longer contact times, reduced flight times, stride frequencies and step lengths, as well as an increase of the centre of mass dynamics. Based on these results it is assumed that runners maintain a certain stiffness level for each velocity despite different loading conditions. As a consequence, Fpeak increases and this probably causes spatiotemporal adjustments in the movement kinematics.  相似文献   

习惯行为、执行意向与青少年身体活动意向与行为:基于计划行为理论的扩展模型     

王丽娟  郑丹蘅 《上海体育学院学报》2020,(2):22-32

在计划行为理论(TPB)的基础上,引入身体活动习惯行为与执行意向,构建扩展TPB(METPB)模型,检验该模型对9~19岁青少年群体的中高强度身体活动(MVPA)的适用性,探讨该模型对小学、初中及高中阶段青少年MVPA影响的差异。结果显示:假设模型的拟合度可以接受,纳入习惯行为与执行意向后,METPB显著地提高了其对身体活动行为的解释力。态度和感知行为控制对MVPA行为意向有显著性影响,解释了31.4%的行为意向方差;行为意向和习惯行为对MVPA行为有显著性影响,解释了18.7%的行为方差;执行意向加强了行为意向朝实际行为的转换。METPB模型对于不同学习阶段青少年MVPA意向及行为的影响有显著性差异。其中:主观规范对小学生与初中生MVPA意向产生了显著性影响,而对高中生的MVPA意向并无显著性影响;感知行为控制对3个阶段学生的MVPA意向产生的影响随着学习阶段的上升不断增强。建议:在对于青少年身体活动的干预中,政府、家庭、学校应重视培养学生对于身体活动参与的正确态度,提高其参与身体活动的意愿,培养其参与身体活动的行为习惯,且在对青少年身体活动干预时考虑学习阶段的差异。  相似文献   

Tracking user-role evolution via topic modeling in community question answering     

Chaogang Fu 《Information processing & management》2019,56(6):102075

Community question answering (CQA) services that enable users to ask and answer questions are popular on the internet. Each user can simultaneously play the roles of asker and answerer. Some work has aimed to model the roles of users for potential applications in CQA. However, the dynamic characteristics of user roles have not been addressed. User roles vary over time. This paper explores user representation by tracking user-role evolution, which could enable several potential applications in CQA, such as question recommendation. We believe this paper is the first to track user-role evolution and investigate its influence on the performance of question recommendation in CQA. Moreover, we propose a time-aware role model (TRM) to effectively track user-role evolution. With different independence assumptions, two variants of TRM are developed. Finally, we present the TRM-based approach to question recommendation, which provides a mechanism to naturally integrate the user-role evolution with content relevance between the answerer and the question into a unified probabilistic framework. Experiments using real-world data from Stack Overflow show that (1) the TRM is valid for tracking user-role evolution, and (2) compared with baselines utilizing role based methods, our TRM-based approach consistently and significantly improves the performance of question recommendation. Hence, our approach could enable several potential applications in CQA.  相似文献   

‘This could be our reality in the next five to ten years’: a blogpost platform as an expectation generation device on the future of insurance markets     

Gert Meyers  Ine Van Hoyweghen 《Journal of Cultural Economy》2018,11(2):125-140

William James (1919) characterises hypotheses as either live or dead. A hypothesis is live when it is taken into account as a ‘real possibility’. We follow James’ suggestion to not attribute intrinsic properties to hypotheses, but rather investigate how they came into being and look at the effects they generate. Expectations of digital technologies are a topic of vivid debate in the insurance industry. Before these expectations can become ‘live’, they have, in the first place, to be generated by market devices. We investigate how the reinsurance blogpost platform Open Minds functions as an ‘expectation generation device’ on the future of insurance markets. Combining Beckert’s work on the role of fictional expectations with the pragmatist turn in sociology of markets, we propose to study ‘expectation generation devices’, provoking expectations on economic markets. In our empirical analysis, we demonstrate the explicit fictional character of the Open Minds contributions, and analyse how a contained space of openness is generated to provoke expectations. We demonstrate how Open Minds can become live through circulation to other expectation generation sites in the insurance industry and beyond. We conclude by reflecting on the importance of expectation generation devices as a particular type of market devices.  相似文献   

高职院校顶岗实习管理机制构建探析     

李耀辉  许春龙  赵成 《苏州市职业大学学报》2021,(1)

顶岗实习是实现高职人才培养目标的重要途径。鉴于当前高职顶岗实习中学校、学生及教师各层面都存在的问题,重新设计了顶岗实习的流程体系,通过校、企、师、生、家五方联动,构建了五途径保障实习岗位、两维度驱动实习成效、四层次规范实习管理、三主体强化实习评价的“五二四三”顶岗实习模式,实现学生、企业、教师、家长、导师和学校的六方共赢。  相似文献   

‘Who is zooming who’? A study of young PE-students in their figurations     

Stine Frydendal Nielsen  Lone Friis Thing 《Sport, Education and Society》2019,24(5):480-490

The article presents an analysis of 93 essays written in an upper secondary school context. The essays were collected in relation to a larger research project, which went on for 5 years in a Danish upper secondary school (2010–2015). The material represents both genders and the students are 15–17 years old. We deploy a theoretical framework taken from Norbert Elias’ notion on established-outsider relations [Elias, N., &; Scotson, J. L. (1994 [1965]). The established and the outsiders. London: SAGE] as well as his use of personal pronouns [Elias, N. (1978). What is sociology? London: Hutchinson, Elias, N. (2001). The society of individuals. New York: The Continuum International Publishing Group] in illustrating how people negotiate, position and navigate within figurational contexts [Elias, N. (1994 [1939]). The civilizing proces. Oxford: Blackwell.]. We do this in an effort to interpret how young people negotiate ‘we-I-relations’ when it comes to their sporting identity. Elias’ processual framework provides a tool for a much needed analysis of how young people continually orientate and develop their sense of selves. The web of human interdependencies and processes of change are key words when it comes to understanding the social practices and doings of the students’ constructions of self-steering. What social scientists may see as laziness and drop-outs of sports [Seippel, Ø. (2016). Prek, vekker og kjedelig? Trening og mening blant ungdom: 1985–2013. In Ø. Seippel, M. K. Sisjord, &; Å Strandbu (Eds.), Ungdom og Idrett. Oslo: Cappelen Damm Akademisk] can in the essays of students be analysed as a struggle for group connectedness and social inclusion in the classroom. The results of our research show that identity is a multiple concept and an ongoing process of emotional work [Elias, N. (1987). On human beings and their emotions: A process-sociological essay. Theory Culture Society, 4, 339–361], but also a power balance of playing and presenting what is imagined as the right performance as not being shamed as outcasts.  相似文献   

学习团队协作信息搜索的共享心智模型研究   总被引：1，自引：0，他引：1  

颜端武  张馨月  汤佳丽  苏琼 《图书情报工作》2020,64(8):3-12

[目的/意义] 对协作信息搜索进行深入研究，为专业化协作信息搜索系统平台建设优化等提供启发和借鉴。[方法/过程] 聚焦于学习团队的信息搜索行为，以高校学生为研究样本，以共享心智模型为切入点，采用扎根理论研究方法，探讨协作信息搜索中团队共享心智模型建构过程。[结果/结论] 识别出四大核心环节——个体感知与探索、团队任务解析、团队信息收集和团队信息整合，并理清各环节的认知活动与共享心智模型内容要素。  相似文献   

图书流通数据分析的H类指数遴选及应用——以西北农林科技大学图书馆为例     

净玲娣  王立宏  王芹  李雅 《图书情报工作》2020,64(9):65-72

[目的/意义] 优化藏书采访工作和流通管理，实现对藏书采访、藏书总量和结构等状况适时监测、评估、调控等的标准化管理。[方法/过程] 通过对H类指数中的H指数、A指数和G指数相关性、变异性和适应性分析，遴选适用于图书流通数据分析的A指数，并根据帕累托定律采用A指数对西北农林科技大学图书馆2014-2018年的前20%的图书流通数据分别进行统计分析。[结果/结论] 研究结果表明：平均A指数对中图法一级类目与读者性别、读者专业、读者年级以及图书出版社、图书出版年、单位等数据统计分析具有较理想的表现，能够更全面、准确地遴选核心读者群、核心出版者和核心出版年；同时发现，布拉德福定律不仅能够应用于期刊管理，而且能够应用于藏书管理。本文研究能够为探索H类指数分析高校图书馆藏书流通数据提供参考依据。  相似文献   

学术论文研究亮点的语言学特征与分布规律研究     

索传军  于果鑫 《图书情报工作》2020,64(9):104-113

[目的/意义] 论文出版过程中，若能够合理有效地呈现出一篇学术论文的核心观点，不仅可以大大减少科研人员在查找和筛选文献上花费的时间，而且有助于阅读与理解。[方法/过程] 通过标注385篇XML格式期刊论文，构建了研究语料库，再利用关键词分析法对亮点的语言学特征进行分析，借助自然语言处理算法探索亮点的分布特征。[结果/结论] 亮点是一组规范的、语义明确的短句的集合，是一篇学术论文与其他论文相比较的新观点、新视角、新方法、新思路、新结果、新结论等内容的体现。亮点具有新颖性、简明性、易读性、"宣传"性等特点。亮点分为研究创新型亮点、研究方法型亮点、研究过程型亮点与研究结论型亮点，本文发现了亮点在正文和各章节的分布情况。  相似文献   

政府数据开放中的公众参与模式:理论构建与案例实证     

陈朝兵  简婷婷 《图书情报工作》2020,64(22):58-68

[目的/意义] 探讨政府数据开放中公众参与的理论模式，旨在指导政府部门有效实现公众参与数据开放的政策目标，以及推进政府数据开放中公众参与议题的研究进展。[方法/过程] 采用文献分析法、逻辑分析法和案例分析法，同时以公众参与阶梯理论作为分析工具，构建并实证政府数据开放中的公众参与模式。[结果/结论] 政府数据开放中的公众参与可从理论层面构建为告知型参与、咨询型参与、合作型参与和授权型参与4种模式，其核心涵义分别是政府向公众传达信息、政府咨询公众意见、政府与公众平等合作、政府与公众共同治理。这4种政府数据开放公众参与理论模式一方面在政府意图、主导力量、信息流动、公众信息知晓度和公众自治程度方面存在明显的特征差异，另一方面从国内外政府数据开放公众参与实践案例中获得良好的经验支持。  相似文献