Effort on homework in grades 5-9: development, motivational antecedents, and the association with effort on classwork

In 2 studies, an expectancy-value framework was applied to investigate effort expended on mathematics homework. In Study 1 (2,712 students in grades 5, 7, and 9; mean age=13.37 years), lower homework effort was found in higher grades. The effects of intrinsic value on homework effort were higher in the older cohorts, whereas the effects of the expectancy component were lower. In Study 2 (571 students in grades 8 and 9; mean age=14.72), an expanded expectancy-value framework was found to explain both homework and classwork variables. The means for effort and value were lower for homework than for classwork; these differences were partly moderated by students' conscientiousness. The implications of homework behavior and motivation for developmental research are highlighted.     

Proximity-to-goal as a constraint on patterns of behaviour in attacker-defender dyads in team games

The aim of this study was to determine whether spatiotemporal interactions between footballers and the ball in 1 vs. 1 sub-phases are influenced by their proximity to the goal area. Twelve participants (age 15.3 ± 0.5 years) performed as attackers and defenders in 1 vs. 1 dyads across three field positions: (a) attacking the goal, (b) in midfield, and (c) advancing away from the goal area. In each position, the dribbler was required to move beyond an immediate defender with the ball towards the opposition goal. Interactions of attacker-defender dyads were filmed with player and ball displacement trajectories digitized using manual tracking software. One-way repeated measures analysis of variance was used to examine differences in mean defender-to-ball distance after this value had stabilized. Maximum attacker-to-ball distance was also compared as a function of proximity-to-goal. Significant differences were observed for defender-to-ball distance between locations (a) and (c) at the moment when the defender-to-ball distance had stabilized (a: 1.69 ± 0.64 m; c: 1.15 ± 0.59 m; P < 0.05). Findings indicate that proximity-to-goal influenced the performance of players, particularly when attacking or advancing away from goal areas, providing implications for training design in football. In this study, the task constraints of football revealed subtly different player interactions than observed in previous studies of dyadic systems in basketball and rugby union.     

Draw a Leaf for Life

阅读提示一个小女孩即将走到人生的尽头,伤心欲绝的妈妈找到了她的画家朋友。这位艺术家为小女孩画了一些树叶。没想到这些树叶竟奇迹般地使这个身患重病的小女孩在绝望中看到了希望。想了解这个故事吗?赶快来读一读吧!     

Patterns and costs of printed and online journal usage

This study in an academic medical sciences library setting examines the correlation of usage of a matched set of print and online titles, the validity of e-journals usage statistics and the impact of online journals on print journal usage. The print and online usage was determined for 270 journals, both versions of which were available. Print usage was determined annually since 1997 using the reshelving and the error-copies method. Online usage statistics were delivered by five publishers and corrected for redundant multiple accesses. Print journal usage decreased by 22.3 and 30.2% respectively over each of 2 years after the introduction of online journals. Journals published both in print and online lost 30.4% of their print usage within 2 years. The total loss of usage of print-only titles in the same period was somewhat higher, at 45.8%. The average correlation between online and print usage is 0.60 and 0.67 respectively. For the examined titles, users accessed the online versions ten times as often as the print version. Two clearly distinguishable groupings emerged: while with Academic Press and Elsevier, e-journal usage exceeded print usage by a factor of 3 or 4, the e-journals of Blackwell, HighWire and Springer were used on average 14.6 times as frequently as the corresponding print journals. Each usage of a print article cost 2.79-50.82 Euro, each usage of an online article 0.31-15.10 Euro, depending on the publisher. On average, the usage of an online article was 5.4 times cheaper. Within 2-3 years the usage of online journals has outstripped that of print titles by a factor of ten, but the specific spectrum of usage remains much the same as when only print journals alone existed. Print titles not available online suffer a greater decline in usage compared with print/online journals. This confirms that what is read or purchased is determined primarily by ease of access and that there is a steady tendency to reduce the multiplicity of access modes to a manageable few. The availability of journals online seems to have created a new clientele, at least in the case of the German-language Springer journals. The connection between supplier and supply is much less clear with e-journals than it is with print titles. Therefore it is very important to stress and encourage the role of the library as the supplier of this sort of information in the university environment. Collection building issues are discussed in the light of the results.     

Maximal oxygen uptake versus maximal power output in children

Maximal oxygen uptake VO(2max)) is considered the optimal method to assess aerobic fitness. The measurement of VO(2max), however, requires special equipment and training. Maximal exercise testing with determination of maximal power output offers a more simple approach. This study explores the relationship between [Vdot]O(2max) and maximal power output in 247 children (139 boys and 108 girls) aged 7.9-11.1 years. Maximal oxygen uptake was measured by indirect calorimetry during a maximal ergometer exercise test with an initial workload of 30 W and 15 W x min(-1) increments. Maximal power output was also measured. A sample (n = 124) was used to calculate reference equations, which were then validated using another sample (n = 123). The linear reference equation for both sexes combined was: VO(2max) (ml x min(-1)) = 96 + 10.6 x maximal power + 3.5 . body mass. Using this reference equation, estimated VO(2max) per unit of body mass (ml x min(-1) x kg(-1)) calculated from maximal power correlated closely with the direct measurement of VO(2max) (r = 0.91, P <0.001). Bland-Altman analysis gave a mean limits of agreement of 0.2+/-2.9 (ml x min(-1) x kg(-1)) (1 s). Our results suggest that maximal power output serves as a good surrogate measurement for VO(2max) in population studies of children aged 8-11 years.     

Explaining long-term exercise adherence in women who complete a structured exercise program

The purpose of this study was to qualitatively examine factors related to physical activity adherence to understand why women continue to participate in long-term exercise after completing a structured exercise program. Data were collected from focus groups, interviews, and e-mails, and analysis used grounded theory. The central category related to physical activity adherence was self-worth. Motivation, activity enjoyment, priorities, body image, ability to access support, and self-regulation skills had an impact on the self-worth of nonadherers and adherers. Women must value themselves enough to continue to participate in physical activity once they start. Exercise and fitness professionals are encouraged to use strategies to increase self-worth and long-term adherence to physical activity. Some recommended strategies include (a) increasing motivation and enjoyment relative to activity, (b) making activity a high priority in a woman's life, (c) improving or deemphasizing body image, (d) increasing a woman's ability to access support, and (e) facilitating the use of self-regulation strategies. This study is the first to examine qualitative perspectives of exercise adherence among women who completed a structured exercise program. Several concepts related to adherence presented in the quantitative literature are confirmed and enhanced in this study.     

What static and dynamic properties should slalom skis possess? Judgements by advanced and expert skiers

Flexural and torsional rigidity are important properties of skis. However, the flexural and torsional rigidity that lead to optimal performance remain to be established. In the present study, four pairs of slalom skis that differed in flexural and torsional rigidity were tested by advanced and expert skiers. Using a 10-item questionnaire, different aspects of the skis' performance were rated on a 9-point scale. For each pair of skis, physical measurements were compared with the ratings of the two groups of skiers. Correlations (Spearman) were then determined between (i) different mechanical properties of the skis (static and dynamic), (ii) subjective assessments of the participants, and (iii) properties of the skis and the participants' assessments. The latter showed that expert skiers rate the aspects of the skis more accurately than advanced skiers. Most importantly, expert skiers are particularly sensitive to torsion of the skis. These results suggest that such highly rated elements should be addressed in future ski designs.     

Quantification of Spinning bike performance during a standard 50-minute class

Spinning is a type of indoor fitness activity performed on stationary bikes by participants who pedal together to the rhythm of music and the motivating words of an instructor. Despite worldwide popularity of this type of recreational activity, to date there have been few, mainly non-scientific, studies of the impact of spinning on metabolic, respiratory, and cardiovascular functions. The main aim of this study was to evaluate a number of metabolic and cardiovascular variables during a standard 50-min class performed by Spinning instructors of both sexes: six males (age 30 +/- 4.8 years, body mass index 24 +/- 2.5 kg x m(-2); mean +/- s) and six females (age 34 +/- 6.3 years, body mass index 21 +/- 1.9 kg x m(-2)). The mean power output, heart rate, and oxygen uptake during the performance were 120 +/- 4 W, 136 +/- 13 beats x min(-1), and 32.8 +/- 5.4 ml x kg(-1) x min(-1) respectively for males, and 73 +/- 43 W, 143 +/- 25 beats x min(-1), and 30 +/- 9.9 ml x kg(-1) x min(-1) respectively for females. Analysis of individual performances showed that they were compatible with physical exercise that ranged from moderate-to-heavy to very heavy, the latter conditions prevailing. The results show that this type of fitness activity has a high impact on cardiovascular function and suggest that it is not suitable for unfit or sedentary individuals, especially the middle aged or elderly, who are willing to begin a recreational physical activity programme.