Trajectories of team and individual sports participation in childhood and links with internalizing problems

The purpose of this 5-year longitudinal study is to identify trajectories of team and individual sports participation in childhood, and to compare these trajectories on different types of internalizing problems. Parents reported their children's annual sports participation from the ages of 6–10 (n = 785) and teachers reported internalizing problems (depression, anxiety, social withdrawal) at the beginning and at the end of this period. The study used latent class growth analyses to identify two trajectories of team sports and two trajectories of individual sports participation were identified: (1) high participation, and (2) low participation. Considering baseline level of internalizing problems and gender, children in the high participation team sports trajectory show significantly fewer depression, anxiety, and social withdrawal behaviors at age 10 than those in the low participation team sports trajectory. No differences between individual sports trajectories were observed. Comparison with joint trajectory groups partially confirmed these results but also showed that sustained participation in multiple individual sports could also be linked to decreased anxiety. Our findings suggest that participation in team sports should be encouraged to promote certain aspects of children's mental health.     

Roof–envelope ratio impact on green roof energy performance

This paper addresses the impact of roof-to-envelope ratio on overall energy savings of a green roof design over conventional roof designs. Simulations were performed using a modified version of the Environmental System Performance program simulator, developed at the University of Strathclyde. The modified design employed a model developed by Columbia University and the Goddard Institute of Space Science which models the evapotranspiritive effect of a green roof calculated using the Bowen ratio; that is, the ratio of sensible heat flux to the surrounding air to the latent heat flux resulting from evapourative energy losses. The resulting heat flux term is proportional to the external surface convection, but inversely proportional to the surface Bowen ratio, which is held constant and chosen to match experimental results obtained for a given roof design. The present study performed simulations for the month of July in a Toronto climate on square warehouse style one, two, and three-story buildings, with windows occupying 10% of the area of each wall. For the first set of simulations, the internal building load of each story was set to zero, and the roof–envelope ratio was increased by increasing the building width and length. For the final simulations, several roof–envelope ratios were chosen, and the internal load of each story was increased from 0 to 50,000 W. As the roof–envelope ratio increases, the cooling load of the upper floor for multi-story designs approaches the entire building cooling load. This indicates the importance of upper zone cooling in total building energy reductions. Furthermore, the total energy savings of a green-roofed building over a conventional roofed building were far more significant for single-story structures. A 250 × 250 m green-roof design with 50,000 W internal loading was found to have percentage energy savings of 73%, 29%, and 18%, for a one, two, and three-story design, respectively.