Sequence-dependent rotation axis changes in tennis     

Clint Hansen  Caroline Martin  Nasser Rezzoug  Philippe Gorce  Benoit Bideau  Brice Isableu 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(3):411-423

The purpose of this study was to evaluate the role of rotation axes during a tennis serve. A motion capture system was used to evaluate the contribution of the potential axes of rotation (minimum inertia axis, shoulder-centre of mass axis and the shoulder-elbow axis) during the four discrete tennis serve phases (loading, cocking, acceleration and follow through). Ten ranked athletes (International Tennis Number 1–3) repeatedly performed a flat service aiming at a target on the other side of the net. The four serve phases are distinct and thus, each movement phase seems to be organised around specific rotation axes. The results showed that the limbs’ rotational axis does not necessarily coincide with the minimum inertia axis across the cocking phase of the tennis serve. Even though individual serving strategies were exposed, all participants showed an effect due to the cocking phase and changed the rotation axis during the task. Taken together, the results showed that despite inter-individual differences, nine out of 10 participants changed the rotation axis towards the minimum inertia and/or the mass axis in an endeavour to maximise external rotation of the shoulder to optimally prepare for the acceleration phase.  相似文献   

Union Civil War Patriotic Covers: An Overview     

Steven R. Boyd  Elaine Prange Turney  David W. Hansen 《Journal of American culture (Malden, Mass. : 2003)》1998,21(3):1-12

  相似文献   

Significant signs: a case study of citation practices in educational research     

Michael Hansen 《International Journal of Research & Method in Education》2016,39(1):74-91

Citations have a central role in the dynamic process of knowledge development and as measures of research performance – yet little is known about their role in educational research or the qualities they are assumed to measure. Based on a citation context analysis, this study shows how a paradigmatic reference within classroom research has been used in 90 articles in educational research journals. Four types of content and four citation functions were identified in the immediate context of the citation symbols. Surprisingly, no critical citations or discussions of the validity of the cited study were found. The results are discussed in relation to the conditions for communication within a field without disciplinary cohesion.  相似文献   

Does More Intensive Neonatal Intensive Care Unit Follow-Up Service Result in Better Outcomes? A Cost-Effective Analysis     

Linda D. Goetze  Nancy Immel  Colette M. Escobar  Yvonne Gillette  Daniel Coury  Nancy Hansen 《Early education and development》1993,4(4):275-289

Little is known about the relative cost-effectiveness of the many different types of early intervention services provided to medically fragile infants and their families. This study compared two intensities of services for such infants and their families: (a) a coordinated and comprehensive system of early intervention services initiated prior to discharge from the NICU and designed to transition infants to community-based services were compared with the effects of services (high intensity); and (b) a more traditional hospital follow-up consisting of medical checkups and referrals following discharge (low intensity). High-intensity services resulted in five times more community-based early intervention hours for families and infants when compared with low-intensity services. Annual costs of the high-intensity group were approximately triple the costs of the low-intensity group ($10,814 versus $3,032 per child per year), but there were only a few statistically significant differences on measures of child and family functioning between the groups at 6-, 12-, 18-, and 24months' corrected age. Implications of these findings for research and practice are given.  相似文献   

Phonological Analysis Skills, Verbal Working Memory, and Reading Ability in Second-Grade Children   总被引：9，自引：0，他引：9  

Julie Hansen  Judith A. Bowey 《Child development》1994,65(3):938-950

This study tested the hypothesis that phonological analysis skills make a unique contribution to reading ability against the hypothesis that one latent phonological factor underlies the assocations among analysis skills, verbal working memory skills, and reading achievement. Hierachical multiple regression analyses examined the unique contributions of phonological analysis and verbal working memory measures to the prediction of 3 measures of concurrent reading ability in 68 second-grade children (mean age 7 years 4 months). Phonological analysis and verbal working memory measures each accounted for unique variation in each of the 3 reading measures. In addition, phonological analysis measures, but not verbal working memory measures, were particularly strong predictors of pseudoword reading skills. These results suggest that, although phonological analysis and verbal working memory skills share a substantial amount of common variance, phonological analysis and verbal working memory tasks do tap somewhat different reading-related skills.  相似文献   

Preschoolers' Understanding of the Link between Thinking and Feeling: Congnitive Cuing and Emotional Change     

Kristin Hansen Lagattuta  Henry M. Wellman  John H. Flavell 《Child development》1997,68(6):1081-1104

In 3 studies we investigated 3- through 6-year-olds' knowledge of thinking and feeling by examining their understanding of how emotions can change when memories of past sad events are cued by objects in the current environment. In Study 1, 48 4-, 5-, and 6-year-olds were presented with 4 illustrated stories in which tocal characters experience minor sad events. Later, each story character encounters a visual cue that is related to one of his or her previous sad experiences. Children were told that the character felt sad and they were asked ot explain why. Study 1 suggested considerable competence as well as substantial development in the years between 4 and 6 in the understandings of the influence of mental activity on emotions. Studies 2 and 3 more systematically explored preschoolers' understanding of cognitive cuing and emotional change with difterent types of situations and cues. Across these 2 studies, 108 3-, 4-, and 5-year-olds listened to illustrated stories that featured story characters who each experienced a sad event and swho were later exposed to a related cue. Children were not only asked to explain why the characters suddenly felt sad, but in some stories, they were also asked to predict and explain how another character, who was never at the past sad event, would feel. Results of studies 2 and 3 showed an initial understanding of cognitive cuing and emotion in some children as young as 3, replicated and extended the evidence for significant developmental changes in that understanding during the preschool years, and revealed that the strenght and consistency of preschoolers' knowledge of cognitive cuing and emotion was affected by whether cues were the sme, or only similar to, parts of the earlier events.  相似文献   

Unpacking Participatory Research in Education   总被引：1，自引：0，他引：1  

Helen P. Hansen  Jennaya Ramstead  Stephen Richer  Susan Smith  Mary Stratton 《Interchange》2001,32(3):295-322

The authors of this paper are members of Ottawa Participatory Researchers in Education (OPRE) a group of teachers, university academics, and students attempting to develop research initiatives using democratic and collaborative research approaches. Building on the experiences of the group, the paper examines and problematizes three elements typically ascribed to non-traditional research approaches: a social action focus, a transformative objective, and a participatory process. Particular emphasis is placed on the questions of who participates, in what ways, and under what conditions. As a result of OPRE's experience and self reflection, seven traps of "pseudo-democracy" are identified and illustrated as potential problems in research purporting to embody equal collaboration between university based academics and community members, such as teachers and students. It is argued that in order to further a democratic research process, equality of opportunity to participate cannot be assumed at any stage of the research process. Attention is paid to the following stages: setting the research agenda, the research epistemology, chronology of the project, representativeness of project participants, funding processes, knowledge cultures, and dissemination choices. Conclusions call for raising awareness of the possibility of teachers and students collaborating to identify research issues of mutual concern and developing a controlling role in research where academics are included as consultants and equals, but not as the possessors of superior and controlling research expertise.  相似文献   

A brief statement of some needs of nontraditional foreign students in American colleges and universities     

Evelyn Unes Hansen 《Innovative Higher Education》1982,6(3):139-141

In recent years, a new population of nontraditional students has emerged in American higher education. That population is made up of foreign nationals and immigrants, refugees, and other aliens. Many of these students have other than traditional credentials. Some have unverifiable credentials, and still others have no credentials at all. Many lack adequate language proficiency, and many are inadequately prepared for success in the fields they have chosen, or been sent, to study. This article presents a glimpse of who these students are, where some are from, and how they are classified. It identifies some of their needs, and states briefly what steps institutions are being urged to take in order to help meet those needs.Professor Hansen is a recipient of the Amoco Foundation-Horace T. Morse Award for Outstanding contributions to Undergraduate Education.  相似文献   

The reliability of linear position transducer,force plate and combined measurement of explosive power-time variables during a loaded jump squat in elite athletes     

Keir T. Hansen  John B. Cronin  Michael J. Newton 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(1):46-58

The purpose of this study was to determine the between day reliability of power-time measures calculated with data collected using the linear position transducer or the force plate independently, or a combination of the two technologies. Twenty-five male rugby union players performed three jump squats on two occasions one week apart. Ground reaction forces were measured via a force plate and position data were collected using a linear position transducer. From these data, a number of power-time variables were calculated for each method. The force plate, linear position transducer and a combined method were all found to be a reliable means of measuring peak power (ICC = 0.87‐0.95, CV = 3.4%‐8.0%). The absolute consistency of power-time measures varied between methods (CV = 8.0%‐53.4%). Relative consistency of power-time measures was generally comparable between methods and measures, and for many variables was at an acceptable level (ICC = 0.77‐0.94). Although a number of time-dependent power variables can be reliably calculated from data acquired from the three methods investigated, the reliability of a number of these measures is below that which is acceptable for use in research and for practical applications.  相似文献   

Beliefs About Thought Probability: Evidence for Persistent Errors in Mindreading and Links to Executive Control     

Kristin Hansen Lagattuta  Liat Sayfan  Christina Harvey 《Child development》2014,85(2):659-674

Four‐ to 10‐year‐olds' and adults' (N = 263) ability to inhibit privileged knowledge and simulate a naïve perspective were examined. Participants viewed pictures that were then occluded aside from a small ambiguous part. They offered suggestions for how a naïve person might interpret the hidden pictures, as well as rated the probability that a naïve person would think of several different pictures (with one picture being the actual item). Results indicated a significant increase between ages 4 and 7 years in attributing novel interpretations; however, all age groups overestimated the probability that a naïve person could guess the actual pictures. Individual differences in working memory and inhibitory control predicted participants' thought suggestions as well as aspects of their probability judgments.  相似文献