排序方式： 共有125条查询结果，搜索用时 15 毫秒
31.
Daniel F. B. Haeufle Jay Worobets Ian Wright Jenny Haeufle Darren Stefanyshyn 《Sports Engineering》2012,15(4):215-220
A common belief in the golf community is that a lighter shaft allows the golfer to swing the club faster. From a mechanical point of view, reducing the mass of the shaft would result in a faster swing. However, a golfer is not a purely mechanical system, and so it is simplistic to assume that identical loads will be applied when swinging different clubs. Therefore, the purpose of this study was to test the hypothesis that golfers behave similar to a mechanical model when swinging clubs of varying mass. A torque driven model estimated the effects caused by the addition of 22?g to the shaft. Twelve golfers hit balls with a standard driver as well as a driver fitted with the same 22?g increase in mass. Club kinematics were collected with a high-speed motion capture system. The model predicted a 1.7?% lower club head speed for the club with additional mass. One subject showed a similar reduction (1.4?%), but one subject showed an increase in club head speed by 3.0?%. Ten subjects did not show any significant differences. These results suggest that golfers do not respond to changes in club mass in a mechanically predictable way. 相似文献
32.
Worobets J Stefanyshyn D 《Sports biomechanics / International Society of Biomechanics in Sports》2012,11(2):239-248
The role of shaft stiffness on the golf swing is not well understood. Studies in which golfers hit balls with clubs of varying shaft flex have reported changes in ball distance. The results of mathematical models suggest that shaft stiffness affects only the orientation of the clubhead at impact, not the speed of the clubhead, but there are no experimental results validating these findings. The purpose of this study was therefore to experimentally examine the influence of shaft stiffness on clubhead kinematics at ball impact. Forty golfers hit 10 balls with each of five drivers varying in shaft stiffness from 'Ladies' to 'Extra-Stiff', in a double-blind study design. The motions of three reflective markers attached to the clubhead were captured with a high-speed motion analysis system. At ball impact, shaft stiffness had a statistically significant influence on clubhead speed for 27 subjects, on loft angle for 11 subjects, and on lie angle for all 40 subjects. No effect was observed on face angle, in to out path angle, or attack angle. These results show that shaft stiffness can affect ball launch conditions by altering clubhead speed and/or loft angle. 相似文献
33.
Festus E. Obiakor Ph.D. Darren J. Smith Ph.D. Marty Sapp Ed.D. 《Multicultural Perspectives》2013,15(2):36-42
Historically, words are powerful! In many cases, they are used appropriately when we value people and used inappropriately when we hate them. As a result, they have become powerful tools in multicultural education and interactions. In today's changing world with demographic shifts in power and paradigm, the society is bombarded with words that hate and words that love. As it appears, words are used to satisfy jaundiced and myopic views, and they are constructs that frequently lead to labels, stereotypes, and illusory generalizations. While we do not advocate policing or legislating words, we advocate words that can help individuals to maximize their fullest potential in our multicultural society. In this article, we advance this premise and suggest ways to increase multicultural education in schools and communities. 相似文献
34.
Nicola Yuill Darren Pearce Lucinda Kerawalla Amanda Harris Rosemary Luckin 《Journal of Research in Reading》2009,32(1):109-125
Two studies assessed the role of Separate Control of Shared Space (SCoSS) technology in supporting peer collaborative discussion and comprehension. We hypothesised that providing equitable shared input to two literacy tasks (both good predictors of comprehension skill) would support discussion to promote the joint construction of meaning, and hence individual progress. Study 1: 50 7–9‐year‐olds took a reading‐specific multiple classification (RMC) pre‐test, categorising words on two dimensions, before training on the task in pairs using SCoSS, dual‐control or individual technology. Discussion produced more accurate post‐test classification performance and SCoSS was associated with higher frequency of statements during training that combined both RMC dimensions (surface form and meaning of words). Study 2: 12 8–9‐year‐olds were pre‐tested on story recall and worked in pairs on a SCoSS‐supported story construction task, requiring collaborative inference‐making, hypothesis generation and selection. Post‐test story recall was predicted by the frequency of deductive causal statements during training. We discuss how technology can be used to promote collaboration and discussion that supports joint understanding and individual comprehension development. 相似文献
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36.
Ricardo Peterson Silveira Pro Stergiou Felipe P. Carpes Flávio A. de S. Castro Larry Katz Darren J. Stefanyshyn 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(2):177-186
The aim of this study was to determine the precision and accuracy of the vertical and anterior–posterior force components of the portable PASCO PS-2142 force plate. Impulse, peak force, and time to peak force were assessed and compared to a gold standard force plate in three different tasks: vertical jump, forward jump, and sprint start. Two healthy male participants performed ten trials for each task, resulting in 60 trials. Data analyses revealed good precision and accuracy for the vertical component of the portable force plate, with relative bias and root mean square (RMS) error values nearly the same in all tasks for the impulse, time to peak force, and peak force parameters. Precision and accuracy of the anterior–posterior component were lower for the impulse and time to peak force, with relative bias and RMS error values nearly the same between tasks. Despite the lower precision and accuracy of the anterior–posterior component of the portable force plate, these errors were systematic, reflecting a good repeatability of the measure. In addition, all variables presented good agreement between the portable and gold standard platforms. Our results provide a good perspective for using the aforementioned portable force plate in sports and clinical biomechanics. 相似文献
37.
Ruth Gwernan‐Jones Darren A. Moore Ruth Garside Michelle Richardson Jo Thompson‐Coon Morwenna Rogers Paul Cooper Ken Stein Tamsin Ford 《British Journal of Special Education》2015,42(3):279-300
Educational policy and the school effectiveness movement often involve rhetoric about the benefit of parent involvement in schools, but high‐quality relationships between parents and teachers are not always straightforwardly achieved, and this may be particularly true in the case of parents of children presenting with academic problems and/or social, emotional and behavioural difficulties. A systematic review of qualitative research was conducted to explore the school‐related experiences of parents of pupils diagnosed with attention deficit hyperactivity disorder (ADHD). Six studies reported in seven papers met the inclusion criteria. High‐quality parent–teacher relationships were found to be the exception, with mothers feeling silenced and criticised. Findings show commonalities with wider research about parents, but identify additional grounds for conflict resulting from parental blame for pupils' disruptive behaviour, and the ambivalent nature of the concept of ADHD. 相似文献
38.
Darren Powell Michael Gard 《Discourse: Studies in the Cultural Politics of Education》2015,36(6):854-867
In this paper, we examine the emergence of what might seem an unexpected policy outcome – a large multinational corporation, frequently blamed for exacerbating childhood obesity, operating as an officially sanctioned driver of anti-obesity initiatives in primary schools across the globe. We draw on Foucault's notion of governmentality to examine the pedagogical work of two international programmes devised and funded by Coca-Cola. We demonstrate how these programmes work simultaneously as marketing campaigns and as governmental strategies to position children as responsible for their own health, conflate (ill)health with body weight and strategically employ the concept of energy balance. We argue that these programmes not only act to unite the interests of corporations, governments and schools, but also seek to use schools to reshape the very ideas of health and a ‘healthy life’. We conclude by considering two sets of ethical and political issues that come sharply as corporations like Coca-Cola continue to exploit the policy space created by the ‘obesity epidemic’. 相似文献
39.
Bradley PS Carling C Archer D Roberts J Dodds A Di Mascio M Paul D Diaz AG Peart D Krustrup P 《Journal of sports sciences》2011,29(8):821-830
The aim of this study was to examine the effect of playing formation on high-intensity running and technical performance during elite soccer matches. Twenty English FA Premier League games were analysed using a multiple-camera computerized tracking system (n = 153 players). Overall ball possession did not differ (P < 0.05) between 4-4-2, 4-3-3 and 4-5-1 formations (50%, s = 7 vs. 49%, s = 8 vs. 44%, s = 6). No differences were observed in high-intensity running between 4-4-2, 4-3-3 and 4-5-1 formations. Compared with 4-4-2 and 4-3-3 formations, players in a 4-5-1 formation performed less very high-intensity running when their team was in possession (312 m, s = 196 vs. 433 m, s = 261 vs. 410 m, s = 270; P 5 0.05) but more when their team was not in possession (547 m, s = 217 vs. 461 m, s = 156 vs. 459 m, s = 169; P < 0.05). Attackers in a 4-3-3 performed ~30% more (P < 0.05) high-intensity running than attackers in 4-4-2 and 4-5-1 formations. However, the fraction of successful passes was highest in a 4-4-2 (P < 0.05) compared with 4-3-3 and 4-5-1 formations. The results suggest that playing formation does not influence the overall activity profiles of players, except for attackers, but impacts on very high-intensity running activity with and without ball possession and some technical elements of performance. 相似文献
40.
Ruth Gwernan-Jones Darren A. Moore Paul Cooper Abigail Emma Russell Michelle Richardson Morwenna Rogers 《Emotional and Behavioural Difficulties》2016,21(1):83-100
This systematic review and synthesis of qualitative research explored contextual factors relevant to non-pharmacological interventions for attention deficit hyperactivity disorder (ADHD) in schools. We conducted meta-ethnography to synthesise 34 studies, using theories of stigma to further develop the synthesis. Studies suggested that the classroom context requiring pupils to sit still, be quiet and concentrate could trigger symptoms of ADHD, and that symptoms could then be exacerbated through informal/formal labelling and stigma, damaged self-perceptions and resulting poor relationships with staff and pupils. Influences of the school context on symptoms of ADHD were often invisible to teachers and pupils, with most attributions made to the individual pupil and/or the pupil’s family. We theorise that this ‘invisibility’ is at least partly an artefact of stigma, and that the potential for stigma for ADHD to seem ‘natural and right’ in the context of schools needs to be taken into account when planning any intervention. 相似文献