Thermal damage to the skin from 8.2 and 95 GHz microwave exposures in swine.

A study of burn thresholds from superficially penetrating radio-frequency (RF) energy at 8.2 and 95 GHz for swine skin was conducted. The study determined the thresholds for superficial, partial-thickness, and full-thickness burn severities after 5 seconds of exposure at power densities of 4-30 W/cm2and 2-15 W/cm2at 8.2 and 95 GHz, respectively. There were significant differences in he burn thresholds at the different severities between the two frequencies due to the large difference in energy penetration depths. Biopsies were collected from each burn site at 1, 24, 72, and 168 hr post exposure. Each sample was assessed by a burn pathologist against 20 histological factors to characterize the damage resulting from these RF overexposures. A one-dimensional, layered digital phantom that utilized realistic values for dielectric and thermal properties was used to explain some observed thresholds. The results of the heating and cooling response of the animal model and histology scores of each exposure are provided to enhance future efforts at simulation of RF overexposures and to establish damage thresholds.

Psychophysiological effects of a brief nocturnal light exposure.

This study compared the effects of a brief pulse (60-minute) of three full spectrum light intensities (1000, 500 and 30 lux) and two green light intensities (1000 and 500 lux) administered between 0200 and 0300 hrs. Ten participants were involved in this repeated measures study. Each participant experienced one condition every week for five weekends. Sessions began at 1800 hours and ended at 0600 hours the following day. Outside of the 60-minute exposure period, each session was spent in 30 lux white light. Oral temperature, salivary melatonin, cognitive performance and subjective mood were sampled throughout the sessions. Analysis revealed that all of the experimental light conditions significantly reduced salivary melatonin concentrations immediately following the pulse. This effect was not maintained beyond the duration of the light pulse. There was no significant effect on oral temperature. There were also no significant effects on cognitive performance and subjective mood, though some positive trends were observed. These results argue that brief, moderate intensity, pulses of either green or full spectrum light are sufficient to suppress the normal nocturnal rise in melatonin. However, the level of suppression obtained does not translate into significant improvement in cognitive performance or subjective mood.