The physiological cost of velocity coupling during tennis groundstrokes     

Cooke K  Davey PR 《Journal of sports sciences》2007,25(7):815-821

Velocity coupling denotes a perceptual motor behaviour known to occur during coincidence timing tasks. Individuals have been shown to increase their effector limb speed with increases in stimulus speed during interceptive tasks. However, little is known about the physiological effects of velocity coupling. The aim of this study was to determine the physiological cost of velocity coupling during tennis groundstrokes. Eight male and eight female competitive tennis players volunteered to perform three 4-min bouts of continuous groundstrokes against balls projected from a tennis ball machine at speeds of 18, 22, and 27 m x s(-1) (65, 79, and 97 km x h(-1)) and a frequency of 14 balls per minute, the order of which was counterbalanced. Breath-by-breath pulmonary gas exchange, heart rate, locomotion time, and limb acceleration were measured throughout each of the 4-min bouts. Capillary blood samples (for blood lactate analysis), rating of perceived exertion, and difficulty rating were taken at the end of each bout. Increasing ball speed did not influence the locomotion time between groundstrokes but did result in a bilateral increase in both the mean upper- and lower-limb acceleration (all P < 0.05). Velocity coupling behaviour increased oxygen uptake, blood lactate concentration, heart rate, rating of perceived exertion, and perceived task difficulty (all P < 0.05). It would appear, therefore, that velocity coupling influenced tennis groundstroke behaviour and indirectly modified the concurrent cardiopulmonary and metabolic responses.  相似文献   

How persistent and general is the contextual interference effect?     

Russell DM  Newell KM 《Research quarterly for exercise and sport》2007,78(4):318-327

The persistence and generality of the contextual interference (CI) effect was tested using a rapid sequential aiming task. Participants (N=48) practiced three movement patterns for three blocks of 18 trials under a blocked (BL) or random (RA) schedule. Movement patterns were displayed and KR provided throughout practice and testing. A 24-hr delayed knowledge of results (KR) retention test included three blocks of 18 trials, followed by a transfer test of a single new movement pattern. In contradiction of the CI effect, RA practice provided an advantage for RA retention only, not BL retention. Furthermore, group differences at transfer were not persistent. Hence, RA practice does not necessarily provide enhanced, context-free learning, but it is essential training for task switching. Overall the findings reveal limited persistence and generality of the CI effect.  相似文献   

Counseling disabled persons throughout the period of further education and training     

Karl H. Seifert 《International journal for the advancement of counseling》1989,12(2):143-151

In this paper the special problems and needs of disabled adults during vocational rehabilitation in rehabilitation centers will be analyzed. For this purpose, the goals and measures of ideal counseling in regard to vocational choice, work and training adjustment, and social adjustment are compared with the results of evaluation studies and studies with drop-outs of these facilities. Conclusions are derived by which measures counselors can contribute essentially to the disabled trainees being better enabled to handle their adjustment problems more effectively.Paper presented at the International Round Table for the Advancement of Counseling Consultation on Counseling Disabled People and their Families, July 4–8, 1987, Vienna, Austria.  相似文献   

Assessing the characteristics of high-quality programs: Lessons from the ohio board of regents fipse study     

Jonathan L. Tafel  Karl Schilling 《Assessment Update》1992,4(6):14-14

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21世纪初图书馆的十大变换化管理   总被引：1，自引：0，他引：1  

顾敏 《图书情报工作》2007,51(12):39-43,47

分析数字革命对图书馆管理的影响，指出图书馆已由自动化管理的时代迈向变换化管理的时代，并提出图书馆的十大项变换化管理范畴，作为图书馆管理2．0概念的起点。  相似文献   

What's difficult,and what isn't: two books published in the 1960s     

Karl Miller 《Changing English: An International Journal of English Teaching》2004,11(2):183-188

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The geometry relevant to modern education     

Karl Menger 《Educational Studies in Mathematics》1971,4(1):1-17

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The Pros and Cons of Graduate Students Working Part-Time in Industry     

Newell  Darrell E. 《Education, IRE Transactions on》1958,1(3):78-81

To provide a method for graduate engineers to acquire advanced degrees, some industrial organizations have instituted a part-time employee program. The difficulties encountered by an industry, an employee and an educational institution which have been involved in such a program are indicated in this paper. Suggestions are made, which should improve the benefits derived from such a program. Since programs of this type will provide a better qualified technical force for industry and the nation, they deserve the attention of educators at this time. Greater cooperation between industry and educational institutions will provide a benefit to all.  相似文献   

An End to Disabling Policies? Toward Enlightened Universal Service     

Gerard Goggin  Christopher Newell 《The Information Society》2000,16(2):127-133

This article argues that an enlightened, inclusive vision of universal service is possible by learning lessons from disability. Telecommunications policy has historically built in norms that needlessly exclude people who are regarded as having a disability and therefore being outside of the mainstream. Accordingly, universal service policies focus on availability and affordability of telecommunications services, rather than on their accessibility and functionality. The article shows how rethinking universal service through disability can lead to inclusive policies that benefit everybody.  相似文献   

GETTING SERIOUS ABOUT THE QUESTIONS OF DEMOCRACY     

Karl Hostetler 《Educational theory》1995,45(1):101-117

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