The McNamara Line and the Turning Point for Civilian Scientist-Advisers in American Defence Policy, 1966-1968     

Twomey  Christopher P. 《Minerva》1999,37(3):235-258

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The perceived impacts of e-government on U.S. cities: A survey of Florida and Texas City managers     

Christopher G. Reddick  Howard A. Frank 《Government Information Quarterly》2007

This study examines the perceived impacts of electronic government or e-government adoption on U.S. cities. This research conducted a survey of Texas and Florida city managers in the fall of 2005 to find out their opinions on the impact of e-government on their city government. The results indicated that e-government is having a positive impact on management, stakeholder involvement, needs and collaboration, and procurement in American cities. There are, however, concerns over spam or unsolicited e-mail and the ability of e-government to reduce the level of staffing. The results of this study imply that, according to city managers' perceptions, e-government adoption in American city governments is positively viewed as having an impact on their organizations and communities.  相似文献   

The High School Mascot as Icon     

Christopher D. Geist 《Journal of American culture (Malden, Mass. : 2003)》1978,1(3):569-573

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Using the internet in the K-12 classroom:     

Christopher?EssexEmail author 《TechTrends》2002,46(3):23-27

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Maximal-intensity isometric and dynamic exercise performance after eccentric muscle actions   总被引：3，自引：2，他引：1  

Byrne C  Eston R 《Journal of sports sciences》2002,20(12):951-959

A well-documented observation after eccentric exercise is a reduction in maximal voluntary force. However, little is known about the ability to maintain maximal isometric force or generate and maintain dynamic peak power. These aspects of muscle function were studied in seven participants (5 males, 2 females). Knee extensor isometric strength and rate of fatigue were assessed by a sustained 60 s maximal voluntary contraction at 80 degrees and 40 degrees knee flexion, corresponding to an optimal and a shortened muscle length, respectively. Dynamic peak power and rate of fatigue were assessed during a 30 s Wingate cycle test. Plasma creatine kinase was measured from a fingertip blood sample. These variables were measured before, 1 h after and 1, 2, 3 and 7 days after 100 repetitions of the eccentric phase of the barbell squat exercise (10 sets x 10 reps at 80% concentric one-repetition maximum). Eccentric exercise resulted in elevations in creatine kinase activity above baseline (274+/-109 U x l(-1); mean +/- s(x)) after 1 h (506+/-116 U x l(-1), P < 0.05) and 1 day (808+/-117 U x l(-1), P < 0.05). Isometric strength was reduced (P < 0.05) for 7 days (35% at 1 h, 5% at day 7) and the rate of fatigue was lower (P < 0.05) for 3 days at 80 degrees and for 1 day at 40 degrees. Wingate peak power was reduced to a lesser extent (P < 0.05) than isometric strength at 1 h (13%) and, although the time course of recovery was equal, the two variables differed in their pattern of recovery. Eccentrically exercised muscle was characterized by an inability to generate high force and power, but an improved ability to maintain force and power. Such functional outcomes are consistent with the proposition that type II fibres are selectively recruited or damaged during eccentric exercise.  相似文献   

Anxiety, arousal and visual attention: a mechanistic account of performance variability     

Janelle CM 《Journal of sports sciences》2002,20(3):237-251

Despite extensive research devoted to determining the nature of the relationship between stress and performance, there has been little systematic examination of the mechanisms underlying this relationship. Recently, researchers have begun to empirically address the attentional mechanisms underlying theoretical accounts of how stress, anxiety and arousal influence performance. Given the critical role of visual attention to sport expertise, this paper focuses primarily on literature dealing with how visual cues are differentially identified and processed when performers are anxious. Emerging evidence indicates that gaze behaviour tendencies are reliably altered when performers are anxious, leading to inefficient and often ineffective search strategies. Alterations of these visual search indices are addressed in the context of both self-paced and externally paced sports events. Recommendations concerning the utility of perceptual training programmes and how these training programmes might be used as anxiety regulation interventions are discussed. The theoretical implications and directions for future research are also addressed.  相似文献   

Motivation for physical activity in young people: entity and incremental beliefs about athletic ability     

Biddle SJ  Wang CK  Chatzisarantis NL  Spray CM 《Journal of sports sciences》2003,21(12):973-989

Three studies are reported of children and youth aged 11-19 years (n = 3478) examining the nature of beliefs about athletic ability. Drawing on related research in academic, moral and stereotyping domains, development of a psychometric instrument assessing athletic ability beliefs is detailed. Support was found for a multidimensional hierarchical structure that is invariant across age and gender. Confirmatory factor analysis revealed a structure comprising two higher-order factors of entity and incremental beliefs underpinned by beliefs that athletic ability is stable and a gift (entity), and is open to improvement and can be developed through learning (incremental). Incremental beliefs, indirectly through a task goal orientation, and entity beliefs directly, predicted self-reported amotivation towards physical education and sport. On the other hand, enjoyment of physical activity in youth was predicted directly by task orientation and incremental beliefs. Predictions concerning the moderating role of perceived competence were not supported. Our findings highlight the importance of ability beliefs and goals in understanding the determinants of physical activity in children and youth.  相似文献   

Mechanisms of attentional cueing during observational learning to facilitate motor skill acquisition     

Janelle CM  Champenoy JD  Coombes SA  Mousseau MB 《Journal of sports sciences》2003,21(10):825-838

We examined the effectiveness of different cueing conditions during observational learning of a soccer accuracy pass. Sixty participants (30 males, 30 females) were randomly assigned and stratified by sex into one of six groups: discovery learning, verbal instruction, video model with visual cues, video model with verbal cues, video model with visual and verbal cues, and video model only. Each participant completed eight blocks of 10 trials each, with trial blocks 1 and 2 representing the practice phase (no manipulation), trial blocks 3, 4, 5 and 6 the acquisition phase (manipulation administered) and trial blocks 7 and 8 the retention phase (24 h after acquisition, with no manipulation). Absolute error, variable error and kicking form were recorded. The results indicated that those who used video modelling with visual and verbal cues collectively displayed less error and more appropriate form across acquisition and retention trial blocks compared with other groups. Our findings suggest that verbal information in addition to visual cues enhances perceptual representation and retention of modelled activities to improve task reproduction capabilities. Future research directions are proposed with implications for both direct and indirect perception accounts of skill acquisition through observed behaviours.  相似文献   

Letter to the editor     

Christopher Zielinski 《Learned Publishing》1998,11(2):88-89

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Examining coaches’ perceptions of how their stress influences the coach–athlete relationship     

Richard C. Thelwell  Christopher R. D. Wagstaff  Michael T. Chapman  Göran Kenttä 《Journal of sports sciences》2017,35(19):1928-1939

This study extends recent coach stress research by evaluating how coaches perceive their stress experiences to affect athletes, and the broader coach–athlete relationship. A total of 12 coaches working across a range of team sports at the elite level took part in semi-structured interviews to investigate the 3 study aims: how they perceive athletes to detect signals of coach stress; how they perceive their stress experiences to affect athletes; and, how effective they perceive themselves to be when experiencing stress. Following content analysis, data suggested that coaches perceived athletes able to detect when they were experiencing stress typically via communication, behavioural, and stylistic cues. Although coaches perceived their stress to have some positive effects on athletes, the overwhelming effects were negative and affected “performance and development”, “psychological and emotional”, and “behavioural and interaction” factors. Coaches also perceived themselves to be less effective when stressed, and this was reflected in their perceptions of competence, self-awareness, and coaching quality. An impactful finding is that coaches are aware of how a range of stress responses are expressed by themselves, and to how they affect athletes, and their coaching quality. Altogether, findings support the emerging view that coach stress affects their own, and athlete performance.  相似文献