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There is little published data in relation to the effects of caffeine upon cycling performance, speed and power in trained cyclists, especially during cycling of approximately 60 s duration. To address this, eight trained cyclists performed a 1 km time-trial on an electronically braked cycle ergometer under three conditions: after ingestion of 5 mg x kg-1 caffeine, after ingestion of a placebo, or a control condition. The three time-trials were performed in a randomized order and performance time, mean speed, mean power and peak power were determined. Caffeine ingestion resulted in improved performance time (caffeine vs. placebo vs. control: 71.1 +/- 2.0 vs. 73.4 +/- 2.3 vs. 73.3 +/- 2.7 s; P = 0.02; mean +/- s). This change represented a 3.1% (95% confidence interval: 0.7-5.6) improvement compared with the placebo condition. Mean speed was also higher in the caffeine than placebo and control conditions (caffeine vs. placebo vs. control: 50.7 +/- 1.4 vs. 49.1 +/- 1.5 vs. 49.2 +/- 1.7 km x h-1; P = 0.0005). Mean power increased after caffeine ingestion (caffeine vs. placebo vs. control: 523 +/- 43 vs. 505 +/- 46 vs. 504 +/- 38 W; P = 0.007). Peak power also increased from 864 +/- 107 W (placebo) and 830 +/- 87 W (control) to 940 +/- 83 W after caffeine ingestion (P = 0.027). These results provide support for previous research that found improved performance after caffeine ingestion during short-duration high-intensity exercise. The magnitude of the improvements observed in our study could be due to our use of sport-specific ergometry, a tablet form and trained participants. 相似文献
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Marcus J. Coleman Tina M. Harris Kevin L Bryant Carrie Reif-Stice 《Journal of International and Intercultural Communication》2018,11(3):173-191
This study explores an under-researched phenomenon of how African Americans communicate about patriotism via ordinary political conversation. We conducted two studies that offer a critical-qualitative analysis of how patriotism is colloquially articulated among African Americans. In study one, focus group interviews were conducted, transcribed, and analyzed using constant comparative method. In study two, we conducted a quantitative content analysis. The findings from study one revealed that there are three relational conceptualizations that help characterize one’s orientation to their nation (i.e., community: subordinate, guardian, and tumultuous). Participants expressed having an attachment to, identification with, and commitment to their communities. 相似文献
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Paul Coleman Library Director Ada D. Jarred Director of Libraries 《The Journal of Academic Librarianship》1994,20(5-6)
Librarians use the Standards for College Libraries in accreditation reviews, and most accrediting bodies, while not formally adopting the Standards, deem them a credible auxiliary tool. A comparison reveals they address issues raised by accreditation criteria. Questions about them remain, however, and a demonstrable basis in research would increase their usefulness. 相似文献
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A study of 10 universities in two states was completed to determine the impact of a change from the quarter to the semester calendar on enrollment patterns and instructional outcomes. A decrease in average student credit hour load and an increase in the percentage of students withdrawing from courses were observed after institutions changed to the semester calendar system.Presented at the 23rd Annual Forum of the Association for Institutional Research, Toronto, May 1983. 相似文献
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Bruce L. Brown Nancy S. Hemmes David A. Coleman Alison Hassin Eva Goldhammer 《Learning & behavior》1982,10(3):365-376
Control of pigeons’ keypecking by a stimulus-reinforcer contingency was investigated in the context of a four-component multiple schedule. In each of three experiments, pigeons were exposed to a schedule consisting of two two-component sequences. Discriminative stimuli identifying each sequence were present only in Component 1, which was 4, 6, or 8 sec in duration, while reinforcers could be earned only in Component 2 (30 sec in duration). Control by a stimulus-reinforcer contingency was sought during Component 1 by arranging a differential relation between Component 1 cues and schedule of reinforcement in Component 2. In Experiment 1, rate of keypecking during Component 1 varied with the presence and absence of a stimulus-reinforcer contingency. When a contingency was introduced, rate of keypecking increased during the Component 1 cue associated with the availability of reinforcement in Component 2. In Experiment 2, the stimulus-reinforcer contingency was manipulated parametrically by varying the correlation between Component 1 cues and Component 2 schedules of reinforcement. Responding in Component 1 varied as a function of strength of the stimulus-reinforcer contingency. The relatively high rates of Component 1 responding observed in Experiments 1 and 2 pose difficulties for conceptions of stimulus-reinforcer control based on probability of reinforcement. In these two experiments, the stimulus-associated probabilities of reinforcement in Component 1 were invariant at zero. An alternate dimension of stimulus-reinforcer control was explored in Experiment 3, in which Component 1 cues were differentially associated with delay to reinforcement in Component 2, while probability of reinforcement was held constant across components. When the stimulus-reinforcer contingency was in force, rate of responding in Component 1 varied inversely with delay to reinforcement in Component 2. In a quantitative analysis of data from Experiments 2 and 3, relative rate of responding during Component 1 was strongly correlated with two measures of relative delay to reinforcement. 相似文献
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Ratings in the Research Assessment Exercise 2001 – the Patterns of University Status and Panel Membership 总被引:1,自引:0,他引:1
Ratings awarded to university departments in the UK Research Assessment Exercise (RAE) 2001 were analysed to determine whether they were influenced either by the status of the university (pre‐1992 or post‐1992) or by whether the university was represented on the panel that determined the ratings. There was little evidence that panel membership has any effect on ratings, but an analysis of covariance also showed that, among universities not on the panel, pre‐1992 universities were more favourably assessed, relative to post‐1992 universities, than would be expected on the basis of their ratings in the 1996 RAE. This finding, along with the preponderance of pre‐1992 universities on all panels (even those where the majority of the research is conducted by post‐1992 universities), is used to urge strongly that in future RAEs, panel membership should be made much more representative of higher education in general and of the institutions submitting the research considered by each panel in particular. 相似文献