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141.
The changes in postural tremor of the hand and the subsequent effect on shooting performance produced by moderate cooling and heating of the forearm were studied in six subjects. Cooling produced a large decrease in tremor size of the ipsilateral hand, whereas warming the limb produced an increase in tremor size. Cooling or warming the forearm did not change the peak frequency of tremor significantly, which was quite stable for each subject. The improvement in shooting performance after cooling the forearm, as measured by grouping pattern of the shots, reached statistical significance and warming caused a significant worsening. This measure of performance was shown to correlate (r = 0.776) inversely with tremor size. The causes and implications of these changes are discussed. It is suggested that local cooling may be useful for people who wish temporarily to reduce tremor in order to improve dexterity for shooting and for other purposes.  相似文献   
142.
Abstract

Swain (1997 Swain, D. P. 1997. A model for optimizing cycling performance by varying power on hills and in wind. Medicine and Science in Sports and Exercise, 29: 11041108. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]) employed the mathematical model of Di Prampero et al. (1979 Di Prampero, P. E., Cortili, G., Mognoni, P. and Saibene, F. 1979. Equation of motion of a cyclist. Journal of Applied Physiology, 47: 201206. [PubMed], [Web of Science ®] [Google Scholar]) to predict that, for cycling time-trials, the optimal pacing strategy is to vary power in parallel with the changes experienced in gradient and wind speed. We used a more up-to-date mathematical model with validated coefficients (Martin et al., 1998 Martin, J. C., Milliken, D. L., Cobb, J. E., McFadden, K. L. and Coggan, A. R. 1998. Validation of a mathematical model for road cycling power. Journal of Applied Biomechanics, 14: 276291. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]) to quantify the time savings that would result from such optimization of pacing strategy. A hypothetical cyclist (mass = 70 kg) and bicycle (mass = 10 kg) were studied under varying hypothetical wind velocities (?10 to 10 m · s?1), gradients (?10 to 10%), and pacing strategies. Mean rider power outputs of 164, 289, and 394 W were chosen to mirror baseline performances studied previously. The three race scenarios were: (i) a 10-km time-trial with alternating 1-km sections of 10% and ?10% gradient; (ii) a 40-km time-trial with alternating 5-km sections of 4.4 and ?4.4 m · s?1 wind (Swain, 1997 Swain, D. P. 1997. A model for optimizing cycling performance by varying power on hills and in wind. Medicine and Science in Sports and Exercise, 29: 11041108. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]); and (iii) the 40-km time-trial delimited by Jeukendrup and Martin (2001 Jeukendrup, A. E. and Martin, J. 2001. Improving cycling performance: How should we spend our time and money?. Sports Medicine, 31: 559569. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]). Varying a mean power of 289 W by ± 10% during Swain's (1997 Swain, D. P. 1997. A model for optimizing cycling performance by varying power on hills and in wind. Medicine and Science in Sports and Exercise, 29: 11041108. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]) hilly and windy courses resulted in time savings of 126 and 51 s, respectively. Time savings for most race scenarios were greater than those suggested by Swain (1997 Swain, D. P. 1997. A model for optimizing cycling performance by varying power on hills and in wind. Medicine and Science in Sports and Exercise, 29: 11041108. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]). For a mean power of 289 W over the “standard” 40-km time-trial, a time saving of 26 s was observed with a power variability of 10%. The largest time savings were found for the hypothetical riders with the lowest mean power output who could vary power to the greatest extent. Our findings confirm that time savings are possible in cycling time-trials if the rider varies power in parallel with hill gradient and wind direction. With a more recent mathematical model, we found slightly greater time savings than those reported by Swain (1997 Swain, D. P. 1997. A model for optimizing cycling performance by varying power on hills and in wind. Medicine and Science in Sports and Exercise, 29: 11041108. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]). These time savings compared favourably with the predicted benefits of interventions such as altitude training or ingestion of carbohydrate-electrolyte drinks. Nevertheless, the extent to which such power output variations can be tolerated by a cyclist during a time-trial is still unclear.  相似文献   
143.
Abstract

We tested hypotheses grounded in self-determination theory regarding athletes' cognitive appraisals and emotional reactions when returning to competition following a serious injury. Professional male athletes (N = 225) competing in the Australian Football League were presented with return-to-competition scenarios that varied with respect to: (1) degree of self-determination and (2) salience of re-injury concern. Significant MANOVA main effects were observed for the degree of self-determination on both primary appraisals and emotional responses as well as for the salience of re-injury concern on emotional response. Follow-up ANOVA polynomial trend analyses provided support for the hypothesized trends for greater self-determination in the return to sport to result in more positive appraisals and affect. Findings support self-determination theory contentions and research indicating the psychological benefits of increased self-determination.  相似文献   
144.
Abstract

Researchers have postulated that hope may be an important factor associated with burnout. Consistent with hope theory contentions, low-hope individuals may be susceptible to burnout because they are prone to experience goal blockage, frustration, and negative affect, all of which likely increase the risk of burnout. We examined the relationship between hope and athlete burnout among 178 competitive athletes (63 females and 115 males) aged 15–20 years. Hope was significantly and negatively correlated with all three burnout subscales: emotional/physical exhaustion, a reduced sense of accomplishment, and sport devaluation. Moreover, results of a multivariate analysis of variance showed that low-hope athletes scored significantly higher than medium- and high-hope athletes on all three burnout dimensions. Finally, results revealed that agency thinking was a significant predictor of all burnout dimensions. Frustration over unmet goals and a perceived lack of agency, a characteristic of low-hope athletes, might pose a risk factor in athlete burnout, whereas being able to maintain hope appears to be associated with health and well-being.  相似文献   
145.
Reviews     
Jeffree, Dorothy M. and Skeffington, Margaret (1980) Let Me Read. MacFarlane, Tom, with Moyle, Donald (adviser), (1980) Comprehension Through the Newspaper. Pugh, A.K., Lee, V.J. and Swann, J. (Ed.) (1980) Language and Language Use. Veatch, Jeannette (1978) Reading in the Elementary School.  相似文献   
146.
The Responsible Anarchist: Postmodernism and social change   总被引:1,自引:0,他引:1  
In recent years, the adoption of postmodern theoretical perspectives within educational research has prompted strong critical reaction. For some critics (particularly Marxist researchers), the greatest fault of postmodernism is that it lacks an agenda for social change. This paper takes issue with this argument, and with four associated arguments: (1) that postmodernism disempowers those to whom it claims to give voice; (2) that it appeals only to intellectuals and has no practical value; (3) that it denies the possibility of the construction of a new social order; and (4) that it colludes with the status quo in its refusal to act. Addressing each of these points in turn, the author suggests that, contrary to the view of these critics, postmodernism offers a powerful force for social change, through the acceptance of uncertainty, the acknowledgement of diversity and the refusal to see concepts such as 'justice' or 'society' as fixed, or as governed by unassailable 'truths'.  相似文献   
147.
In spite of the challenges inherent in making dozens of comparisons across heterogeneous populations, a relatively recent interest in scale-score equivalence for non-achievement measures in an international context has emerged. Until recently, operational procedures for establishing measurement invariance using multiple-groups analyses were typically supported with research that was limited in scope to few groups and relatively small sample sizes. Recent research that examined situations more representative of international surveys recommended some revisions to typically used fit measures. The current study extends this research and evaluates the performance of several fit measures when data are assumed to have an ordered categorical, rather than the typically assumed continuous, scale. Using a simulation study based on empirical results, findings indicated that classic measures and associated criteria were either unsuitable in a large-group and varied sample-size context or should be adjusted, particularly when observed variables were not normally distributed. We provide specific recommendations for revising currently used criteria for evaluating overall and relative fit based on the chi-square test, root mean-squared error of approximation, and comparative fit index (CFI).  相似文献   
148.
Minds, modules, and meta-analysis   总被引:5,自引:0,他引:5  
Wellman and colleagues' meta-analysis of performance on the false-belief task is methodologically useful, but it does not lead to any theoretical progress concerning the nature of the mechanisms that underlie the existence and development of "theory of mind." In particular, the results of this meta-analysis are perfectly compatible with "early competence" accounts that posit a specific, innate, and possibly modular basis for theory of mind. The arguments presented by Wellman and colleagues against such views stem not from their meta-analytic data, but from mistaken assumptions regarding the requirements of such theories (e.g., that there exist manipulations that improve performance only, or to a greater degree, in young children). Contrary to what Wellman and colleagues claim, their meta-analysis, while consistent with conceptual change, does not lend any new support for such theories.  相似文献   
149.
Six-month-old infants' categorization of containment spatial relations   总被引:1,自引:0,他引:1  
Six-month-old infants' ability to form an abstract category of containment was examined using a standard infant categorization task. Infants were habituated to 4 pairs of objects in a containment relation. Following habituation, infants were tested with a novel example of the familiar containment relation and an example of an unfamiliar relation. Results indicate that infants look reliably longer at the unfamiliar versus familiar relation, indicating that they can form a categorical representation of containment. A second experiment demonstrated that infants do not rely on object occlusion to discriminate containment from a support or a behind spatial relation. Together, the results indicate that by 6 months, infants can recognize a containment relation from different angles and across different pairs of objects.  相似文献   
150.
This study employed a national sample of college students who initially aspired to be, or later became, physicians to determine the influence of precollege characteristics, college origins, and the academic and social experience of college on the likelihood of becoming a physician. Estimates of a 14-variable causal model indicated that the major direct effects on attainment were attributable to college characteristics and the academic experience of college. Net of other causes, the selectivity/prestige of the undergraduate institution attended, collegiate academic achievement, and majoring in the physical or life sciences each had significant direct effects on becoming a physician. The direct positive influence of college quality, however, was partially counterbalanced by its negative indirect effect. Moreover, the greatest advantage in attending an elite institution accrued to those students with relatively high levels of academic performance. As academic performance declined, so did the positive effect of college quality. The effects of precollege characteristics on becoming a physician were largely indirect, mediated by the student's college experience. Net of other factors, women were no less likely than men to become physicians, but being female had a significant negative indirect effect. Conversely, secondary school achievement did not directly influence attainment but did have a large positive indirect influence.An earlier version of this paper was presented at the annual meeting of the Association for the Study of Higher Education, San Diego, February, 1987.  相似文献   
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