Nontraumatic Exertional Fatalities in Football Players, Part 1: Epidemiology and Effectiveness of National Collegiate Athletic Association Bylaws.

Background: Football has the highest number of nontraumatic fatalities of any sport in the United States.

Purpose: To compare the incidence of nontraumatic fatalities with that of traumatic fatalities, describe the epidemiology of nontraumatic fatalities in high school (HS) and college football players, and determine the effectiveness of National Collegiate Athletic Association (NCAA) policies to reduce exertional heat stroke (EHS) and exertional sickling (ES) with sickle cell trait (SCT) fatalities in athletes.

Study Design: Descriptive epidemiology study.

Perception of physical variables during four phases of the menstrual cycle.

Comparisons of perceptions during four menstrual phases were collected with 6 regularly menstruating athletes who responded to a semantic differentiation scale containing descriptive polar terms. Analysis indicated a significantly lower mean score on perceived strength and speed during the progestational phase and a lower mean for power during menstrual and progestational phases.

Mie scattering from a sonoluminescing air bubble in water.

A single bubble of air in water can emit pulses of blue-white light that have durations of less than 50 ps while it is oscillating in an acoustic standing wave. The emission is called sonoluminescence. A knowledge of the bubble diameter throughout the cycle, and in particular near the time of sonoluminescence emission, can provide important information about the phenomenon.