Reduction of peak expiratory flow after a 5-meter dive with extreme exertion

The effects of physically exerting scuba dives on the airways are expected to affect the respiratory system and therefore the spirometric flow indices directly after surfacing. After on-air open-sea dives, the flow indices were examined with standard spirometry (maximal forced expiration) within 10 minutes pre- and post-dive. Twenty volunteers, age 49 ± 14 years (m ± SD) equipped with a dive computer to record the dive profile, cylinder pressures and water temperature (27°C), as well as a heart rate monitor, performed 5-meter dives of 27 minutes at maximal swimming velocity (v). Mean pulmonary ventilation (PV) was 48 ± 10 ambient L/minute (aL.min-1). Mean v was 34 ± 6 meters/minute and mean heart rate 143 beats per minute, about 80% of the on-land theoretical maximum. None of the flow variables changed except a decrease of 7.1% ± 8.3 (p=0.001) of the peak expiratory flow (PEF), pre-dive of 11.2 ± 2.7 L/minute. A likely major cause of the reduction of PEF is expiratory muscle fatigue. A small contribution of subclinical pulmonary edema cannot be excluded. The inhalation of dry air and the cooling of the airways are expected to affect PEF minimally. Although the change is normally clinically irrelevant, during emergency it may be of importance

Influence of atmospheric electric fields on the radio emission from extensive air showers

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Probing atmospheric electric fields in thunderstorms through radio emission from extensive air showers

We present measurements of radio emission from extensive air showers taking place during thunderstorms. Their intensity and polarization patterns are different from those observed during fair-weather conditions. We introduce a simple two-layer model for atmospheric electric fields which can reproduce the main features of the intensity and polarization patterns of air shower during thunderstorms. This in turn provides a unique way to probe atmospheric electric fields