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11.
Background: Motor skill (MS) competence is an important contributing factor for healthy development.

Purpose: The goal was to test the effectiveness of primary school physical education (PE) on MS and physical fitness (PF) development.

Methods: Three classes (n?=?60, aged 9.0?±?0.9) were randomly assigned to three diverse conditions during a school year: two PE lessons/week (PE-2), three PE lessons/week (PE-3), and no PE lessons control group (CG). BMI, skinfolds, PF (9-min run/walk, sit-up, modified pull-ups), gymnastics, soccer, handball, basketball and track-and-field skills were evaluated. Effect sizes (d) were reported as magnitude of change.

Results: Skinfolds significantly increased only in CG (d?=?1.21). PF composite z-scores improved in PE-3 (d?=?0.61), but decreased in PE-2 (d?=?0.57), and had no changes in CG. Statistically significant improvement was verified in gymnastics and handball skills in both experimental groups (gymnastic: d?=?2.95 and d?=?2.61 for PE-3 and PE-2, respectively; handball: d?=?1.87 and d?=?0.57 for PE-3 and PE-2, respectively), and no changes were seen in CG. In soccer, there were improvements only in the PE-3 (d?=?0.55), and in basketball only in PE-2 (d?=?0.46). There were no changes in any group for track-and-field skills.

Conclusions: PE programs can effectively promote PF and MS development.  相似文献   
12.
The aim of this study was to determine the influence of breathing frequency and tidal volume on resting heart rate variability in children aged 9 years (n = 29) and 16 years (n = 19). Heart rate variability was measured in four conditions: (1) without the control of ventilation followed at random by (2) a fixed breathing frequency of 12 breaths x min(-1), (3) a breathing frequency of 12 breaths x min(-1) but with a fixed tidal volume of 30% vital capacity and (4) a fixed breathing frequency of 6 breaths x min(-1) and a tidal volume of 30% vital capacity. A total of 128 RR intervals (the time between two spikes in the heart rate) were detected and absolute high- and low-frequency spectral components were calculated using autoregressive modelling. The younger children were unable to control ventilation to achieve conditions 3 and 4; therefore, a 2 x 2 (group x condition) analysis of variance was used to analyse conditions 1 and 2. There were significant interactions between group and heart rate variability conditions for the low-frequency component and the ratio of low to high frequencies (P < 0.001). The main effect for condition showed that at 12 breaths x min(-1) with no fixed tidal volume there was a significantly higher standard deviation of the RR interval, total power and high-frequency (P< 0.01) and low-frequency spectral components (P < 0.05) than in the condition with no ventilatory control. Across the four breathing conditions for the older participants, the high-frequency spectral component was significantly higher in the condition at 6 breaths x min(-1) with a fixed tidal volume than in that with no ventilatory control (P < 0.005); the ratio of high to low frequencies was significantly lower for the spontaneous condition than those performed at 12 breaths x min(-1) (P < 0.001). The results provide evidence of the need for ventilatory control when assessing short-term resting heart rate variability in children.  相似文献   
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According to the literature, there is a very important corpus of knowledge that allows for the investigation of some dimensions of ‘learning experience’ provided to students, in relation to epistemic, pedagogical and meta-cognitive practices. However, in the literature, there is little investigation into the invariance (or not) of the characteristics of students’ learning experience while being taught a scientific subject by the same teacher. This paper suggests that the relationship between the learning experience provided and the competences developed is not properly highlighted. This paper analyses the learning experience provided to students in epistemic, pedagogical and meta-cognitive terms. The students were taught the proprieties and applications of light by one teacher, in three classes, over 7 weeks. We analysed the data in each referred learning experience, using a pre-defined category system. The students’ competences were evaluated by a competence test. The epistemic demand of each item and the students’ performances were also analysed. Our findings point to the non invariance of learning experiences provided to students and the influence of some dimensions of learning experiences provided in the development of certain competences. These findings and their implications are contextualized and discussed.  相似文献   
19.
We test the hypothesis that scientific collaboration is associated with increased publication productivity. We differentiate our approach from other studies by (a) incorporating professional networks in the productivity model, (b) casting productivity and collaboration as distinct phenomena, and (c) examining these phenomena in the context of resource-constrained research institutions in a developing country. We use survey data and employ negative binomial regression models. Results indicate that publication productivity is significantly linked to professional network factors, but there is no evidence of any association with scientific collaboration. We observe that most scientists collaborate in research projects despite coordination difficulties, and without any measurable impact on their productivity. Our interviews reveal that a possible answer to this puzzle appears to be rooted in a practice that views collaborative research projects not mainly as a means to producing knowledge and gaining recognition, but for acquiring professional opportunities and extrinsic rewards. Our findings suggest a new way of modeling publication productivity, with implications for science and innovation policy in both the developed and the developing world.  相似文献   
20.
Foreign firms patent in emerging economies with weak appropriability regimes at an increasing rate. This phenomenon constitutes a paradox since in such a setting foreign firms should have weak incentives to patent. In an attempt to resolve this paradox, we conducted an inductive analysis of 11 foreign firms that patent in such a setting, using the case of China as our empirical context. We identify four archetypes of foreign firms and three key antecedents the interaction of which determines which archetype a firm can be subsumed under.Our study complements the developed-economy focus of the extant appropriation literature by adding an international perspective. We extend previous econometric studies by identifying salient factors on the firm level that determine the extent to which a foreign firm patents in emerging economies with a weak appropriability regime, highlighting that the extent of a firm's motivation to maintain its freedom to operate can supersede imitability concerns. We also comment on the practical implications of these contributions for managers of foreign firms. Highlighting a structural conflict of interest between foreign firms from developed economies and the development goals of an emerging economy, we point to the generalizability of our results to a wide range of other emerging economies worldwide.  相似文献   
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