OBJECTIVE Adolescents' leisure activities are increasingly focusing on Internet activities, and today, these coexist with traditional leisure activities such as sport and meeting friends. The purpose of the present study was to investigate leisure activities, particularly Internet activities, among boys and girls with ADHD, and compare these with boys and girls from the general population. The ...

BACKGROUND It is unknown how atrial fibrillation (AF) is actually initiated by triggers. Based on consistencies in atrial structure and function in individual patients between episodes of AF, we hypothesized that human AF initiates when triggers interact with deterministic properties of the atria and may engage organized mechanisms. METHODS AND RESULTS In 31 patients with AF, we mapped AF ini...

Inclusive fitness theory predicts that organisms will tend to help close kin more than less related individuals. In a variety of birds and mammals, relatives are recognized by comparing their phenotype to an internal representation or template, which might be learned through either repeated exposure to family members or self-inspection. Mirrors are ubiquitous now, but were absent during our evo...

OBJECTIVE To compare the distribution and observation of helmet use patterns among 4 common childhood leisure activities-bicycle riding, in-line skating, skateboarding, and scooter riding-in a setting with no helmet use legislation. DESIGN A cross-sectional, unobtrusive, direct observation of children engaged in 1 of the 4 activities was conducted during an 8-week period. SETTING Eight comm...