Reconciling multiple sources of influence: Longitudinal associations among perceived parent,closest friend,and popular peer injunctive norms and adolescent substance use

Prospective associations over a 5-year period were examined among perceived parent, closest friend, and popular peer injunctive norms and the onset and frequency of adolescent substance use within a diverse (53% female, 45.5% White non-Hispanic, 22.3% Hispanic, 21.5% Black, 1% Asian, and 6.4% another race) sample of 868 seventh- and eighth-grade adolescents from 2012 to 2017. Analyses revealed adolescents' substance use norms were more lenient than perceptions of their parents' and stricter than perceptions of their closest friends'. Stricter perceptions of parent and closest friend norms, but not popular peer norms, were significantly associated with a later onset of alcohol, marijuana, and cigarette use, and the magnitude of the effect of each source' on later substance use varied across development.     

The effect of shaft flexibility on junior golfers' performance

The aims of this study were to examine the effect of shaft flexibility on the performance of junior golfers and to determine whether there is a relationship between golfers' physical characteristics (16 anthropometric measures, age, experience, strength), performance and shaft flexibility. We assessed the performance of 30 male golfers, aged 7–10 years, with three 7-iron golf clubs of different shaft flexibility at a driving range. The performance parameters measured for equipment evaluation were ball distance achieved, shot dispersion and impact position of the ball on the clubface. The results suggest that there is no particular shaft flex suitable for the age group considered and that experience, strength and arm span are the significant factors when selecting optimal shaft flexibility for children.