Characterising the impact performance of field hockey sticks   总被引：1，自引：1，他引：0  

Tom Allen  Leon Foster  Matt Carré  Simon Choppin 《Sports Engineering》2012,15(4):221-226

Published research on field hockey equipment is scarce. The aim of this research was to investigate methods for characterising the impact performance of field hockey sticks. Three sticks were used with fundamental frequencies in the range 74?C154?Hz. Striking an initially still ball with a stick was identified as the preferred method for characterising performance. Impacts were simulated at mean velocities of 19?m/s at toe and 16?m/s at the shaft. The mean apparent coefficient of restitution and standard deviation were ?0.32?±?0.05 at the toe and ?0.18?±?0.02 at the shaft. The foundation work presented here provides the foundations for developing a methodology for characterising the impact performance of field hockey sticks.  相似文献   

Movement variability in the golf swing     

Langdown BL  Bridge M  Li FX 《Sports biomechanics / International Society of Biomechanics in Sports》2012,11(2):273-287

Traditionally, golf biomechanics has focused upon achieving consistency in swing kinematics and kinetics, whilst variability was considered to be noise and dysfunctional. There has been a growing argument that variability is an intrinsic aspect of skilled motor performance and plays a functional role. Two types of variability are described: 'strategic shot selection' and 'movement variability'. In 'strategic shot selection', the outcome remains consistent, but the swing kinematics/kinetics (resulting in the desired ball flight) are free to vary; 'movement variability' is the changes in swing kinematics and kinetics from trial to trial when the golfer attempts to hit the same shot. These changes will emerge due to constraints of the golfer's body, the environment, and the task. Biomechanical research has focused upon aspects of technique such as elite versus non-elite kinematics, kinetics, kinematic sequencing, peak angular velocities of body segments, wrist function, ground reaction forces, and electromyography, mainly in the search for greater distance and clubhead velocity. To date very little is known about the impact of variability on this complex motor skill, and it has yet to be fully researched to determine where the trade-off between functional and detrimental variability lies when in pursuit of enhanced performance outcomes.  相似文献   

Hamlin Garland's Detour into Art Criticism: Forecasting the Triumph of Popular Culture over Populism at the End of the Frontier     

Matt Johnston 《Journal of American culture (Malden, Mass. : 2003)》2011,34(4):346-356

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Celebration,USA: The First Sign of What Will Be America's Homogeneous Landscape     

Matt Thomas 《Journal of American culture (Malden, Mass. : 2003)》2007,30(2):187-197

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网络技术:改进数据访问的性能     

Matt Haynos 《中国传媒科技》2007,(7)

谈起网格,肯定要涉及数据、信息以及如何在分布式的基础设施上对二者进行智能化处理.而这个时候似乎更让大家着迷的是网格的计算能力,而数据在以计算为重点的网格中仅能占据次席.  相似文献   

Motivational interviewing: theory,practice and applications with children and young people,edited by E. McNamara     

Matt Stiles 《Emotional and Behavioural Difficulties》2014,19(3):329-331

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The Closing of the Professorial Mind: A Meditation on Plato and Allan Bloom     

Matt Silliman 《Educational theory》1990,40(1):147-151

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Is it wrong to play violent video games?     

Matt McCormick 《Ethics and Information Technology》2001,3(4):277-287

Many people have a strong intuition that there is something morallyobjectionable about playing violent video games, particularly withincreases in the number of people who are playing them and the games'alleged contribution to some highly publicized crimes. In this paper,I use the framework of utilitarian, deontological, and virtue ethicaltheories to analyze the possibility that there might be some philosophicalfoundation for these intuitions. I raise the broader question of whetheror not participating in authentic simulations of immoral acts in generalis wrong. I argue that neither the utilitarian, nor the Kantian hassubstantial objections to violent game playing, although they offersome important insights into playing games in general and what it ismorally to be a ``good sport.' The Aristotelian, however, has a plausibleand intuitive way to protest participation in authentic simulations ofviolent acts in terms of character: engaging in simulated immoral actserodes one's character and makes it more difficult for one to live afulfilled eudaimonic life.  相似文献   

Individual Differences in the Stability and Change of Childhood Depression: A Growth Mixture Model With Structured Residuals     

Matt Hawrilenko  Katherine E. Masyn  Janine Cerutti  Erin C. Dunn 《Child development》2021,92(4):e343-e363

Studies of developmental trajectories of depression are important for understanding depression etiology. Existing studies have been limited by short time frames and no studies have explored a key factor: differential patterns of responding to life events. This article introduces a novel analytic technique, growth mixture modeling with structured residuals, to examine the course of youth depression in a large, prospective cohort (N = 11,641, ages 4–16.5, 96% White). Age-specific critical points were identified at ages 8 and 13 where depression symptoms spiked for a minority of children. Most depression risk was due to dynamic responses to environmental events, drawn not from a small pool of persistently depressed children, but a larger pool of children who varied across higher and lower symptom levels.  相似文献   

Relationships and learning: a review and investigation of narrative coherence in looked‐after children in primary school     

Anne Greig  Helen Minnis  Reuben Millward  Claire Sinclair  Eilis Kennedy  Kate Towlson 《Educational Psychology in Practice》2008,24(1):13-27

This review and investigation draws on principles from attachment theory regarding the importance of early relationships and their impact on the coherence and organisation of psychological functions. Comparisons are made between the narrative coherence scores of an experimental group of 17 looked‐after children with problematic relationship histories in mainstream school and a matched control group of 17 of their peers. There were significant differences between the groups in the coherence of children's narratives, denial and avoidance in story play themes and in their use of intentionality. The paper considers the theory and discusses the results in terms of the implications for teaching, learning and intervention.  相似文献