The force–time profile of elite front crawl swimmers     

Danielle P. Formosa  Bruce Mason  Brendan Burkett 《Journal of sports sciences》2013,31(8):811-819

Abstract

In this study, we used recently developed technology to determine the force–time profile of elite swimmers, which enabled coaches to make informed decisions on technique modifications. Eight elite male swimmers with a FINA (Federation Internationale de Natation) rank of 900+ completed five passive (streamline tow) and five net force (arms and leg swimming) trials. Three 50-Hz cameras were used to video each trial and were synchronized to the kinetic data output from a force-platform, upon which a motorized towing device was mounted. Passive and net force trials were completed at the participant's maximal front crawl swimming velocity. For the constant tow velocity, the net force profile was presented as a force–time graph, and the limitation of a constant velocity assumption was acknowledged. This allowed minimum and maximum net forces and arm symmetry to be identified. At a mean velocity of 1.92 ± 0.06 m · s^?1, the mean passive drag for the swimmers was 80.3 ± 4.0 N, and the mean net force was 262.4 ± 33.4 N. The mean location in the stroke cycle for minimum and maximum net force production was at 45% (insweep phase) and 75% (upsweep phase) of the stroke, respectively. This force–time profile also identified any stroke asymmetry.  相似文献   

Quantifying stroke coordination during the breathing action in front-crawl swimming using an instantaneous net drag force profile     

Danielle P. Formosa  Mark G.L. Sayers  Brendan Burkett 《Journal of sports sciences》2013,31(18):1729-1737

Abstract

This study used both an instantaneous net drag force profile and a symmetry timing to evaluate the effect of the breathing action on stroke coordination. Twenty elite swimmers completed a total of six randomised front-crawl towing trials: (i) three breathing trials and (ii) three non-breathing trials. The net drag force was measured using an assisted towing device mounted upon a Kistler force platform, and this equipment towed the swimmer at a constant speed. The net drag force profile was used to create a stroke symmetry index for each swimming trial. Analysis using the symmetry indices identified that the majority of participants demonstrated an asymmetrical instantaneous net drag force stroke profile in both the breathing and non-breathing conditions, despite no significant differences in the time from finger-tip entry to finger-tip exit. Within the breathing condition, the faster swimmers compared to the slower swimmers demonstrated a lesser percentage of overlap between stroke phases on their breathing stroke side. During the non-breathing condition, the faster participants compared to the slower swimmers recorded a reduction in the percentage of overlap between stroke phases and less duration in the underwater stroke on their breathing stroke side. This study identified that the majority of participants demonstrated an asymmetrical net drag force profile within both conditions; however, asymmetry was less prevalent when examining with only the timing symmetry index.  相似文献   

Assessment of decision-making performance and in-game physical exertion of Australian football umpires     

Paul Larkin  Brendan O’Brien  Christopher Mesagno  Jason Berry  Jack Harvey  Michael Spittle 《Journal of sports sciences》2013,31(15):1446-1453

Abstract

The aim of this study is to investigate the effects of in-game physical exertion on decision-making performance of Australian football umpires. Fifteen Australian football umpires (M_age = 36, s = 13.5 years; M_{games umpired} = 235.2, s = 151.3) volunteered to participate in the study. During five competitive Australian football pre-season games, measures of in-game physical exertion (blood lactate levels, global positioning system [GPS]) and decision-making performance (video-based test) were obtained. There were no significant correlations between physical exertion in a particular quarter and decision-making performance in either the same quarter or any other quarter. Video-based decision-making performance was effected by time in game χ²(3) = 24.24, P = 0.001, with Quarter 4 performance significantly better than both Quarter 2 and Quarter 3. In-game physical exertion (blood lactate) significantly decreased over the course of the game χ²(3) = 11.58, P = 0.009. Results indicate no definable link between in-game physical exertion and decision-making performance. It is, however, presumed that decision-making performance may be affected by the time or context of the game. Future research is warranted to explore the relationship between physical exertion and decision-making performance to potentially inform Australian football umpire training programmes that replicate in-game physical and decision-making demands.  相似文献   

Transatlantic moves to the market: the United States and the European Union     

Sheila Slaughter  Brendan Cantwell 《Higher Education》2012,63(5):583-606

The theory of academic capitalism is used to explore US and EU marketization trajectories. Comparisons are made along the following dimensions: creation and expansion of intermediating organizations external to universities that promote closer relations between universities and markets; interstitial organizations that emerge from within universities that intersect various market oriented projects; narratives, discourses and social technologies that promote marketization and competition; expanded managerial capacity; new funding streams for research and programs close to the market; and new circuits of knowledge that move away from peer review and professional judgment as arbiters of excellence. We also consider the status of fields not closely integrated with external markets, and see fragmentation of the humanities, fine arts and (some) social sciences to be a sign of research universities marketization. We conclude that the US and EU are following very different paths to bring higher education closer to the market. The US move to the market was incremental and frequently led by a wide variety of non-governmental organizations, often with strong ties to the for-profit sector and participation by segments of universities prior to federal legislation or mandates. The European Commission is reverse engineering Anglo-American higher education models to reconstruct technologies of governance in uniquely European contexts that embed competition in nation-state initiatives. Although the discourse surrounding university marketization promises growth of high paying jobs prosperity, evidence to date suggests very uneven results for both the US and EU.  相似文献   

Internationalization of the postdoctorate in the United States: analyzing the demand for international postdoc labor     

Brendan Cantwell  Barrett J. Taylor 《Higher Education》2013,66(5):551-567

The American academic research enterprise relies heavily on contributions made by foreign nationals. Of particular note is the large number of international postdocs employed at universities in the United States (US). Postdocs are among the fastest growing group of academic staff in the US, and over 50 % of all postdocs in the US are temporary visa holders. While academic mobility is sometimes understood using a ‘push–pull’ model, we argue that demand for educational migrants must be considered. Drawing from Marginson’s (Handbook on globalization and higher education. Edward Elger, Northampton, 2011; Marginson and Rhoades in High Educ 43:281–309, 2002) work, we develop a model for assessing local, national, and institutional (or local) variables that may shape the employment of international postdocs at universities in the United States, and we operationalize the model through a panel regression analysis using data covering the period 1989–2009. We find that the passage of time and federally supported research and development expenditures are strong predictors of postdoc employment. Institutional characteristics predict changes only in the subsample of private universities.  相似文献   

Experimental validation of the belfield infant assessment profile     

Brendan J. Spelman  Bernadette A. McHugh 《Irish Educational Studies》2013,32(1):203-220

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CIPA: A Brief History     

Brendan P. Menuey 《学校用计算机》2013,30(1):40-47

Passed in 2000, the Children's Internet Protection Act (CIPA) mandates Internet filtering for all public schools and libraries. Challenges to the law have been raised on constitutional grounds by free-speech advocates such as the American Library Association and the American Civil Liberties Union. After losing one such challenge in district court, the federal government appealed to the U.S. Supreme Court, where the law was upheld in June 2003, though not without possible future concerns. CIPA has profound implications for K–12 school leaders and technology specialists, and a history of the law reveals much about its origins and purpose.  相似文献   

Zambia's Catholic schools and secularization     

Brendan Carmody 《History of education》2013,42(4):357-371

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Will there be faith? A new vision for education and growing disciples     

Brendan Carmody 《British Journal of Religious Education》2013,35(1):118-120

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Assessing the public university     

Brendan Cantwell 《British Journal of Sociology of Education》2013,34(1):152-161

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