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A new method was established for the continuous measurement of force applied from a springboard to a gymnast in vaulting (board reaction force). Male gymnasts performed a handspring vault using a springboard mounted on force platforms. A high-speed video camera sampled the springboard motion at 500 Hz. The springboard was initially partitioned into 29 segments. The force due to the accelerative motion of the springboard was determined by summing the forces of the individual segments. The board reaction force acting on the gymnast was calculated by subtracting the force due to the accelerative motion of the springboard and weight from the force recorded by the force platform. The new method succeeded in illustrating transient changes of the board reaction force. The horizontal and vertical components of the peak values of the board reaction force were three and two times greater respectively than the average values. A series of tests was conducted to determine whether the number of segments of the springboard model could be reduced without affecting accuracy. A model consisting of only four segments produced almost the same accuracy as the 29-segment model. The simplified model is recommended as a more efficient method to measure board reaction force. 相似文献
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Tommy Shane Steiner 《海外英语》2007,(6):17
有着俊朗外貌的Tommy Shane Steinerr以纯正的乡村歌喉演唱着属于他牛仔风格的歌曲。他出道后,受到了许多前辈的关注和提携:连续11年主持乡村音乐协会年度颁奖典礼的歌星Vince Gill出人意料地为Steiner的主推曲What If She’s An Angel配唱了合 相似文献
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The purpose of the present study was to investigate how self-concept and attributional style are related to depression in a student group. On the basis of an inventory, 166 advanced teacher students were scored on general and academic self-esteem, attribution for positive and negative events, and depression. The two self-esteem variables were found to constitute important predictors of depression, while the contributions of the attributional variables were of minor importance. In addition, pessimistic attributions to both positive and negative events resulted in higher depression than pessimistic attributions to either kind of events, and to neither kind of events. Finally, factor analysis resulted in interpretable solutions. 相似文献
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We argue in this paper that the systematic use of special software in instruction has a profound impact on the notion of function as an abstract entity to be constructed. We argue that through the medium of the computer, the objects in the graphical, tabular and algebraic settings can change their essence and thus become objects of a new kind we callrepresentatives. Actions on representatives which naturally arise in this framework induce an ontological shift. A taxonomy of the skills involved in the learning of the concept of function through these new ontological lenses is presented, as well as software, and problem solving tasks that embody the same ontological perspective. Within the framework of a teaching experiment, students' acquisition of many of the identified skills was investigated by means of a questionnaire and interviews during computer supported problem solving sessions. The most salient results of the study indicate that a majority of students were able (1) to cope with partial data about functions (e.g., problems of interpolation and arbitrariness), (2) to recognize invariants (i. e., properties of functions) while coordinating actions among representatives from different settings, and (3) to recognize invariants while creating and comparing different representatives from the same setting. 相似文献
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Daniel H. Robinson Stephanie B. Corliss Angela M. Bush Stephan J. Bera Tommy Tomberlin 《Educational technology research and development : ETR & D》2003,51(4):25-41
In three experiments, we investigated the optimal presentation of graphic organizers (GOs) and text by having undergraduates
read a chapter-length text in its entirety, a few pages at a time, or a few sentences at a time, before or after viewing seven
GOs in their entirety (large bites), one at a time (small bites), or one cell at a time (animated). Large bites were better
than small bites for learning concept relations and applying that knowledge, and for recalling macropropositions when the
GOs were presented before text. Animated GOs offered no advantages over the large-bites GOs at first presentation and considerably
extended total study time. Presenting several GOs first, followed by the entire text, appears to be optimal in directing students’
attention to across-chapter relations in text. 相似文献
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Drawing from Cervantes-Soon’s (2012) framework of testimonios as confessions, counter-narratives, and consejos, we explore how writing letters to our children serves as a process of historical documentation, healing, and a passing down of social justice principles and family history. Additionally, we expand on Cervantes-Soon’s framework by utilizing testimonios as a process by which to affirm intergenerational memory. Finally, connections are made to the potential role of letter writing as an important pedagogical tool. 相似文献