Techniques used in high-scoring and low-scoring 'Roche' vaults performed by elite male gymnasts     

Takei Y  Dunn JH  Blucker E 《Sports biomechanics / International Society of Biomechanics in Sports》2003,2(2):141-162

The 16 highest-scored Roche vaults (G1) performed during the 2000 Olympic Games were compared with those receiving the 16 lowest-scores (G2). A 16-mm motion picture camera operating at 100 Hz recorded the vaults during the competition. The results of t tests (p < .05) indicated G1, compared to G2, had (a) shorter time of board support, greater normalised average upward vertical force and backward horizontal force exerted by the board, greater change in the vertical velocity while on the board, and greater vertical velocity at board take-off, (b) comparable linear and angular motions in pre-flight, (c) smaller backward horizontal impulse exerted by the horse, smaller loss of the horizontal velocity while on the horse, and greater horizontal and vertical velocities at horse take-off, (d) greater height and larger horizontal distance of post-flight, (e) higher body mass centre at knee release, and (f) higher mass centre, greater normalised moment of inertia, and smaller vertical velocity at mat touchdown. Therefore, gymnasts and coaches should focus on sprinting the approach; blocking and pushing-off the take-off board rapidly and vigorously; departing the board with a large vertical velocity; exerting large downward vertical force and small forward horizontal force from the hand-stand position while on the horse; departing the horse with large horizontal and vertical velocities; and completing the majority of the double salto forward near the peak of trajectory and releasing the knees above the top of the horse to prepare for a controlled landing.  相似文献   

Somersaulting techniques used in high-scoring and low-scoring Roche vaults performed by male Olympic gymnasts     

Takei Y  Dunn JH  Blucker EP 《Journal of sports sciences》2007,25(6):673-685

The aim of this study was to compare the somersaulting techniques used in the 16 highest-scoring and 16 lowest-scoring Roche vaults. Our hypothesis was that the gymnasts performing the highest-scoring Roche vaults would demonstrate a better technique than those performing the lowest-scoring Roche vaults while on the horse (pushing off the horse more effectively), somersaulting (executing most of the required somersaults higher in flight), and landing (showing a greater control). A 16-mm motion picture camera, operating at 100 Hz, recorded the vaults during the official competition. The two-dimensional direct linear transformation was used for spatial reconstruction. The results of t-tests (P < 0.05) indicated that, compared with the low-scoring gymnasts, the high-scoring gymnasts had: (1) greater height of body centre of mass and a more fully extended body position at the horse take-off; (2) greater height of body centre of mass at the peak of post-flight, knee release, and touchdown on the mat; (3) greater horizontal and vertical displacements of body centre of mass, greater somersaulting rotation, and longer time from the knee release to mat touchdown; and (d) markedly smaller landing point deductions. In conclusion, a successful Roche vault is likely when the focus is on: (a) leaving the horse with a large vertical velocity in an extended body position to achieve a high trajectory of centre of mass by first extending the legs, then immediately pushing off the horse vigorously, using the muscles of the upper extremity; (b) grasping the knees immediately after the take-off from the horse, achieving the tightly tucked body position early during the ascent to the peak, and completing two-thirds of the required somersaults at a great height; (c) releasing the knees and extending the body above the top level of the horse; and (d) contacting the mat with a high body centre of mass position.  相似文献   

Analyzing mathematics classroom cultures and practices     

Erik De Corte  Lieven Verschaffel 《International Journal of Educational Research》2007,46(5):247-251

  相似文献   

Genetic and Environmental Etiologies of the Longitudinal Relations Between Prereading Skills and Reading          下载免费PDF全文

Micaela E. Christopher  Jacqueline Hulslander  Brian Byrne  Stefan Samuelsson  Janice M. Keenan  Bruce Pennington  John C. DeFries  Sally J. Wadsworth  Erik Willcutt  Richard K. Olson 《Child development》2015,86(2):342-361

The present study explored the environmental and genetic etiologies of the longitudinal relations between prereading skills and reading and spelling. Twin pairs (n = 489) were assessed before kindergarten (M = 4.9 years), post‐first grade (M = 7.4 years), and post‐fourth grade (M = 10.4 years). Genetic influences on five prereading skills (print knowledge, rapid naming, phonological awareness, vocabulary, and verbal memory) were primarily responsible for relations with word reading and spelling. However, relations with post‐fourth‐grade reading comprehension were due to both genetic and shared environmental influences. Genetic and shared environmental influences that were common among the prereading variables covaried with reading and spelling, as did genetic influences unique to verbal memory (only post‐fourth‐grade comprehension), print knowledge, and rapid naming.  相似文献   

Youths’ socialization to work and school within the family     

Bora Lee  Erik J. Porfeli 《International Journal for Educational and Vocational Guidance》2015,15(2):145-162

  相似文献   

Organisational forms of science communication: the UK and Spanish European higher education systems as paradigms     

Ojeda-Romano  Gabriela  Fernández-Marcial  Viviana  Wilkinson  Clare  Stengler  A. Erik 《Higher Education》2022,84(4):801-825

As key elements in research and development systems, higher education institutions have been taking a leading role when it comes to communicating science and technology, but their performance has been inconsistent so far. In this critical and comparative study of the UK public engagement model and the Spanish scientific culture model, eighteen practitioners from higher education institutions across both regions were interviewed. A mixed qualitative data analysis has been performed identifying similarities and differences that unravelled the science communication management model in the two different higher education systems. This article provides evidence on how the institutionalisation of science communication is strongly influenced by key driving forces in the higher education context as well as the policies of administrations and other agents.

  相似文献   

Introduction letter     

Erik De Graaff acting Editor-In-Chief 《European Journal of Engineering Education》2008,33(1)

  相似文献   

Subversion in the Swamp: Pogo and the Folk in the McCarthy Era     

Erik Dussere 《Journal of American culture (Malden, Mass. : 2003)》2003,26(1):134-141

  相似文献   

Szenario-basierter Systemtest von Software-Produktfamilien     

Andreas Reuys  Erik Kamsties  Klaus Pohl und Sacha Reis 《Informatik - Forschung und Entwicklung》2005,20(1-2):33-44

Zusammenfassung In der Produktfamilienentwicklung werden durch zwei Entwicklungsprozesse, Domain und Application Engineering, zun"achst wiederverwendbare Entwicklungsartefakte produziert, um diese anschlie?end zur Konstruktion von kundenspezifischen Applikationen einzusetzen. Die Wiederverwendbarkeit wird durch die explizite Definition der Variabilit"at der geplanten Applikationen einer Produktfamilie erzielt. Diese proaktive Wiederverwendung ist bisher in den konstruktiven Entwicklungsphasen realisiert, jedoch noch nicht im Test. Mit ScenTED (Scen_ario based TE_st Case D_erivation) wird in diesem Beitrag eine wiederverwendungsorientierte Technik zur Testfallerstellung f"ur den Systemtest, dem Test eines ausf"uhrbaren Systems gegen spezifizierte Use-Cases, von Produktfamilien vorgestellt. ScenTED basiert auf zwei Kernideen: der Erhaltung der Variabilit"at in Testf"allen und der Szenario-basierten Verfeinerung der Testf"alle. Durch die Erhaltung der Variabilit"at wird die Wiederverwendbarkeit von Testf"allen gesichert; die Szenario-basierte Verfeinerung erm"oglicht Nachvollziehbarkeit durch die durchg"angige Nutzung von Szenarien. In diesem Beitrag wird die ScenTED-Technik an einem Beispiel erl"autert und Erfahrungen aus dem industriellen Einsatz diskutiert.

---

Product family engineering consists of two development processes: Domain engineering and application engineering. Reuseable artefacts are created in the domain engineering process. These artefacts are used for the creation of customer specific applications during the application engineering process. Reusability is achieved with the explicit definition of variability that specifies the potential applications of the product family. The proactive reuse has been realized in the construnction phases of the development process, but not within the test phases. We propose ScenTED (Scen_ario based TE_st Case D_erivation) for the creation of reusable test cases for a use case based system testing in product family engineering. ScenTED has two key ideas: The first is the preservation of variability in test cases and the second idea is the scenario-based refinement of test cases. The preservation of variability ensures the reusability of test cases. The scenario-based refinement enables the traceability from requirements to test cases. We present the ScenTED technique in this article with an example and discuss an industrial case study.

CR Subject Classification D2.5  相似文献   

Sympathy for the devil: Reconsidering Ernst Mach’s empiricism     

Erik C. Banks 《Metascience》2012,21(2):321-330

  相似文献