Comparing the pre- and post-impact ball and racquet kinematics of elite tennis players' first and second serves: a preliminary study   总被引：1，自引：0，他引：1  

Chow JW  Carlton LG  Lim YT  Chae WS  Shim JH  Kuenster AF  Kokubun K 《Journal of sports sciences》2003,21(7):529-537

The aim of this study was to compare the pre- and post-impact three-dimensional kinematics of the ball and racquet during first and second serves performed by elite tennis players. Data were collected from four male and four female right-handed professional players during competition using two high-speed cameras (200 Hz). For each player, one first serve and one second serve from the 'deuce' or right service court that landed within the specified target area were analysed. To test for significant differences between the first and second serves, Wilcoxon tests (P < or = 0.05) were performed on selected parameters. The results indicate that the ball travelled forward and to the left during the flight phase of the toss in all but one trial. The average pre-impact ball forward location for the first serve was significantly more in front and had a higher associated forward ball velocity than the corresponding values for the second serve. On average, the decrease in post-impact ball speed from the first to the second serve was 24.1%. No significant differences between the first and second serves were found in the pre-impact racquet head speed and orientation, which was represented as a unit vector perpendicular to the racquet face. The major adjustments made by the players when going from the first to second serve were a decrease in pre-impact ball forward location (P < or = 0.01) and an increase in the pre-impact racquet vertical and lateral velocities (both P < or = 0.05). This implies that the players tossed the ball closer to the body and imparted topspin and sidespin on the ball by changing the racquet vertical and lateral velocities when going from the first to the second serve.  相似文献   

Testing for Sex Inequality in Standardized Admission Exams: The Case for Open Access     

Brian Powell  Lala Carr Steelman 《Equity & Excellence in Education》2013,46(3-5):86-88

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On State SAT Research: A Response to Wainer     

Brian Powell  Lala Carr Steelman 《Journal of Educational Measurement》1987,24(1):84-89

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正义、美德与教育（英文）     

大卫·卡尔 《中学教育》2015,(1):30-39

如果说正义是人类道德交往的基本法则或者维度,那么这也似乎适用于一些教育问题。简而言之,我们需要教育孩子和年轻人正义和公平。然而,这并不是可以仅通过教授正义的理论就能够实现的。因为,正如这篇文章所揭示的那样,这些理论通常涉及到维护正义的准则,即在有些情况下,公民个体不能总是做到如其所期待的那样正义与公平。所以,正义教育更多的是培养正义的美德。从这点出发,本文致力于探究如何借助富有想象力的文学作品来培养正义的美德。  相似文献   

Mentoring: Where do We go From Here?     

Rowan Carr 《Pastoral Care in Education》2006,24(4):58-59

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Amplitude-modulated sinusoidal microchannels for observing adaptability in C. elegans locomotion     

Parashar A  Lycke R  Carr JA  Pandey S 《Biomicrofluidics》2011,5(2):24112

In this paper, we present a movement-based assay to observe adaptability in Caenorhabditis elegans locomotion behavior. The assay comprises a series of sinusoidal microchannels with a fixed wavelength and modulating (increasing or decreasing) amplitude. The channel width is comparable to the body diameter of the organism. Worms are allowed to enter the channel from the input port and migrate toward the output port. Within channel sections that closely match the worm's natural undulations, the worm movement is relatively quick and steady. As the channel amplitude increases or decreases along the device, the worm faces difficulty in generating the propulsive thrust, begins to slow down and eventually fails to move forward. A set of locomotion parameters (i.e., average forward velocity, number and duration of stops, range of contact angle, and cut-off region) is defined for worm locomotion in modulated sinusoidal channels and extracted from the recorded videos. The device is tested on wild-type C. elegans (N2) and two mutants (lev-8 and unc-38). We anticipate this passive, movement-based assay can be used to screen nematodes showing difference in locomotion phenotype.  相似文献   

Book Review     

David Carr 《Journal of Philosophy of Education》1997,31(3):515-518

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Endurance training adherence in elite junior netball athletes: a test of the theory of planned behaviour and a revised theory of planned behaviour     

Palmer CL  Burwitz L  Dyer AN  Spray CM 《Journal of sports sciences》2005,23(3):277-288

This study examined the utility of Ajzen's (1985) theory of planned behaviour and Maddux's (1993) revised theory of planned behaviour to predict endurance training intentions and adherence of elite junior netball athletes. One hundred and fifteen athletes from the England Netball World Class Start Programme were assessed on constructs central to the predictions of the two theories. Adherence to a recommended endurance training programme was recorded in self-report diaries across a 9-week period. Validity for the diaries was supported by significant correlations (P < 0.001) with recalls across 7 days and 9 weeks. Adherence was moderate and variable between athletes (mean = 66.05, s = 25.75%). Two separate path analyses were conducted to examine the predictions of the theories. Goodness-of-fit indices suggested acceptable fit of the data to the models. Analyses showed that attitude towards the new behaviour, subjective norms and perceived behavioural control predicted training intentions. The relationship between intention and adherence was weak. The present results suggest that the constructs of the theory of planned behaviour offer some insight into the explanation of intentions to follow an endurance training programme. Constructs unique to the revised theory of planned behaviour did not significantly predict training intentions or behaviour. Implications for practitioners working with team sport performers are provided.  相似文献   

Informed choice and deaf children: underpinning concepts and enduring challenges   总被引：3，自引：0，他引：3  

Young A  Carr G  Hunt R  McCracken W  Skipp A  Tattersall H 《Journal of deaf studies and deaf education》2006,11(3):322-336

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Non-traditional students in tertiary education: inter-disciplinary collaboration in curriculum and pedagogy in community services education in Australia     

Angela Daddow  Peter Moraitis  Amanda Carr 《International Journal of Inclusive Education》2013,17(5):480-489

Education policy in Australia has accelerated its aim to increase participation of under-represented groups in tertiary education including students who are culturally and linguistically diverse and have low socio-economic status. These students generally have not had prior access to privileged academic discourse, which can further disadvantage them in their participation and progress in tertiary education. In this article, we outline a cross-discipline curriculum initiative and pedagogy that draws on critical literacy and the metaphor of discourse community to integrate language and academic skills into community services qualifications. We argue that this – supports the genuine participation of under-represented (non-traditional) students. It aspires to not only support students’ entry into the new academic terrain, but to enable students to adopt a critical stance to the discourses in which they are learning to participate. This we argue is crucial, when expertise is not just a way of meeting its ostensible purposes, but is also a way of exercising power. Although we report on the application of this initiative to entry level curricula (Diploma), we suggest that it has relevance and application to Bachelor levels in a range of disciplines, both in supporting pedagogy and for transition to Bachelor level study.  相似文献