School-based prevention: effects on obesity and physical performance after 4 years

Juvenile obesity is increasing worldwide. Preventive strategies are warranted. The school-based Children's Health Interventional Trial (the CHILT Project) combines health education and physical activity for children. The effect on obesity and physical performance was studied after four years in 12 primary schools compared with five control schools. Anthropometric data were recorded. Physical performance was measured by a coordination test for children (balancing backwards, one-legged obstacle jumping, lateral jumping, sideways movements) and a 6-min run (endurance). No difference in the prevalence and incidence of overweight and obesity was found between the intervention and control schools before and after the intervention. Remission of overweight was higher in the intervention schools (23.2 vs. 19.2%), but not significant. An increase in coordination related to lateral jumping and balancing backwards was apparent in the intervention schools (30.6, s = 10.8 vs. 26.1, s = 10.8, P = 0.005; 21.8, s = 11.8 vs. 19.4, s = 11.7, P = 0.007), and the increase in endurance performance tended to be higher in intervention schools (100.8, s = 122.7 vs. 92.8, s = 126.0, P = 0.055), adjusted for age, sex, baseline test result, and body mass index at final examination. Therefore, preventive intervention in primary school offers the possibility to improve physical performance in children. The prevalence and incidence of obesity were not affected.     

Designing and Developing Assessments of Complex Thinking in Mathematics for the Middle Grades

Designing an assessment system for complex thinking in mathematics involves decisions at every stage, from how to represent the target competencies to how to interpret evidence from student performances. Beyond learning to solve particular problems in a particular area, learning mathematics with understanding involves comprehending connections among mathematical ideas and applying them in ways that may not have been taught directly. A challenge in characterizing mathematical competency is to capture not only the variety of skills and concepts, but also their connections. Designing assessments based on learning progressions may be one way to respond to this challenge. We discuss our experience developing a learning progression and an associated task model for mathetical functions.     

The Shifting Relationship between Vocational and Higher Education in France and Germany: towards convergence?

In Europe, the Bologna and Copenhagen Processes in higher education (HE) and vocational education and training (VET) are on the agenda, aiming to create a European educational area. Acknowledging important differences between countries, we compare the evolving relationship between HE and VET. We ask whether and how these two distinct organisational fields in France and Germany have changed in recent decades. Comparing institutional shifts, the article analyses whether long-standing differences in postsecondary education and training systems and the education/economy nexus in these two countries have remained stable. We argue that these countries’ skill formation systems have begun to converge, departing from their original institutionalisation paths. Thus, while the traditional typologies that contrast France and Germany have served as useful heuristic devices, they require revision to adequately represent incremental institutional change in these skill formation systems resulting from endogenous reforms and exogenous pressures due to Europeanisation.     

Heat transfer variations of bicycle helmets

Abstract

Bicycle helmets exhibit complex structures so as to combine impact protection with ventilation. A quantitative experimental measure of the state of the art and variations therein is a first step towards establishing principles of bicycle helmet ventilation. A thermal headform mounted in a climate-regulated wind tunnel was used to study the ventilation efficiency of 24 bicycle helmets at two wind speeds. Flow visualization in a water tunnel with a second headform demonstrated the flow patterns involved. The influence of design details such as channel length and vent placement was studied, as well as the impact of hair. Differences in heat transfer among the helmets of up to 30% (scalp) and 10% (face) were observed, with the nude headform showing the highest values. On occasion, a negative role of some vents for forced convection was demonstrated. A weak correlation was found between the projected vent cross-section and heat transfer variations when changing the head tilt angle. A simple analytical model is introduced that facilitates the understanding of forced convection phenomena. A weak correlation between exposed scalp area and heat transfer was deduced. Adding a wig reduces the heat transfer by approximately a factor of 8 in the scalp region and up to one-third for the rest of the head for a selection of the best ventilated helmets. The results suggest that there is significant optimization potential within the basic helmet structure represented in modern bicycle helmets.     

Chronische koronare Herzkrankheit

Ohne Zusammenfassung     

建立在几何交互式教学基础上的因特网

随着计算机的广泛普及和互联网的迅猛发展，数学教育也越来越朝着信息化、媒体化的方向发展，进而带来数学教育的深刻变化。在几何教学过程中，教育者应充分利用计算机作为图形计算器来处理几何问题。这将给学生巨大的探索和实验的空间，应用先进的多媒体技术进行教学活动，对改变传统的数学课堂教学模式，实现研究性学习和开放式教学有着积极的促进作用。     

International research networks: Determinants of country embeddedness

Research activities are increasingly global so that embeddedness in international knowledge networks is decisive for inventive and innovative performance. We analyze determinants of countries’ embeddedness in the global photovoltaics knowledge network for the period 1980–2015 and argue that positions in this network are determined by the structure and functionality of national research systems and by instruments within the policy-mix for renewable energies. We show that cohesion and connectedness of the national research system positively affect international embeddedness, whereas centralized systems are detrimental to embeddedness. This indicates that a diffusion oriented research system allows better access to international knowledge flows. Policy instruments, especially demand side instruments, show a positive effect on embeddedness.