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Several arrangements of relay, condenser, and battery can be made to oscillate dependably. The electrical properties of these oscillators, as well as of a number of derivative devices, are here outlined.  相似文献   
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This study investigated the acute endocrine responses to a 164-km road cycling event in a hot environment. Thirty-four male experienced cyclists (49.1 ± 8.3 years, 86.8 ± 12.5 kg, 178.1 ± 5.1 cm) participating in a 164-km road cycling event were recruited. Blood samples were collected within 0.3–2.0 h before the start (PRE: ~0500–0700 h) and immediately following the ride (POST). Samples were analysed for testosterone, growth hormone (GH), cortisol and interleukin-6 (IL-6). The temperature and humidity during the event were 35.3 ± 4.9°C and 47.2 ± 14.0%, respectively. Based on the finishing time, results for the fastest (FAST, 305 ± 10 min) and the slowest (SLOW, 467 ± 31 min) quartiles were compared. At POST, testosterone concentration was significantly (P < 0.05) lower (PRE, 20.8 ± 8.6; POST, 18.2 ± 6.7 nmol · L?1), while GH (PRE, 0.3 ± 0.1; POST, 2.3 ± 0.3 µg · L?1), cortisol (PRE, 661 ± 165; POST, 1073 ± 260 nmol · L?1) and IL-6 (PRE, 4.0 ± 3.4; POST, 22.4 ± 15.2 pg · mL?1) concentrations were significantly higher than those at PRE. At POST, GH and cortisol were significantly higher for the FAST group than for the SLOW group (GH, 3.6 ± 2.0 and 1.0 ± 0.8 µg · L?1; cortisol, 1187 ± 209 and 867 ± 215 nmol · L?1). Participation in an ultra-endurance road cycling event in a hot environment induced significant acute changes in concentrations of circulating hormones, with a greater augmentation of GH and cortisol in those completing the ride fastest.  相似文献   
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The purpose of this study was to examine the mediating effect of resistance training skill competency on percentage of body fat, muscular fitness and physical activity among a sample of adolescent boys participating in a school-based obesity prevention intervention. Participants were 361 adolescent boys taking part in the Active Teen Leaders Avoiding Screen-time (ATLAS) cluster randomised controlled trial: a school-based program targeting the health behaviours of economically disadvantaged adolescent males considered “at-risk” of obesity. Body fat percentage (bioelectrical impedance), muscular fitness (hand grip dynamometry and push-ups), physical activity (accelerometry) and resistance training skill competency were assessed at baseline and post-intervention (i.e., 8 months). Three separate multi-level mediation models were analysed to investigate the potential mediating effects of resistance training skill competency on each of the study outcomes using a product-of-coefficients test. Analyses followed the intention-to-treat principle. The intervention had a significant impact on the resistance training skill competency of the boys, and improvements in skill competency significantly mediated the effect of the intervention on percentage of body fat and the combined muscular fitness score. No significant mediated effects were found for physical activity. Improving resistance training skill competency may be an effective strategy for achieving improvements in body composition and muscular fitness in adolescent boys.  相似文献   
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The purpose of this study was to determine if achievement on a series of problems was affected by differences among task values within a dimension. Values within inference pattern, goal object, and percept dimensions were studied. One hundred and sixty primary school children participated in the study. An analysis of the results of their achievement on the tasks indicate that task solution is affected by the dimension values used in this study. The results of the study suggest that a multidimensional scale of task dimension values should be constructed in order to assist the curriculum specialist in the construction and sequencing of concept tasks for specific grade levels.  相似文献   
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This study assessed the perceptions of 146 gifted and 115 non-gifted high school biology students and investigated associations between student perceptions and cognitive achievement. The What Is Happening In this Class? (WIHIC) was used to assess perceptions of actual and preferred learning environments. Data indicated that all students preferred a more favourable environment than the one that they were currently experiencing, but gifted students perceived their actual environment more positively than non-gifted students. Statistically significant associations between the actual learning environment and achievement on a standardised biology test were found for the majority of scales. Teacher Support, Investigation and Equity were all statistically significant independent predictors of student achievement, while Student Cohesiveness had a negative association with achievement. Interviews revealed that students interpreted some WIHIC items differently from how the developers had intended.  相似文献   
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This study summarizes prior reviews of new media and Internet research, and the growth of the term Internet in academic publications and online newsgroups. It then uses semantic network analysis to summarize the interests and concepts of an interdisciplinary group of Internet researchers, as represented by session titles and paper titles and abstracts from the 2003 and 2004 Association of Internet Researchers conferences. In both years, the most frequent words appearing in the paper abstracts included Internet, online, community, social, technology, and research. The 2003 papers emphasized topics such as the social analysis/research of online/Internet communication, community, and information, with particular coverage of access, individuals, groups, digital media, culture; role and process in e-organizations; and world development. The 2004 papers emphasized topics such as access; news and social issues; the role of individuals in communities; user-based studies; usage data; and blogs, women, and search policy, among others.  相似文献   
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This study investigated the relative merits of using teacher judgment and the Slosson Full-Range Intelligence Test to estimate the math and reading achievement of students in a summer remedial-reading program. The subjects included children in grades kindergarten through six who were enrolled in the Auburn University Summer Clinic. Components analyses showed that the Slosson Full-Range Intelligence Test recovered substantially more variance from the distributions of the KeyMath-Revised and the Woodcock Reading Mastery Tests-Revised than did teacher judgments. Analysis of variance showed that significant differences between the means of the three tests resulted from the inclusion of students with learning disabilities. Implications of the results are discussed.  相似文献   
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