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Simultaneous measurements of bubble density in the sea subsurface and positive ions in the lower atmosphere were performed in the Baltic Sea in the summer of 1999. Bubbles in two size ranges, around 27 and 100 μm, were measured acoustically. Airborne positive charge was measured with a Gerdien instrument. Observed concentrations of air ions varied from 60 cm−3 up to 600 cm−3. The relative role of bubbles and wind speed on the positive air ion concentrations over the brackish water of the Baltic Sea is discussed. The parameters of a model of a log-log dependence between charge concentration and bubble density are calculated. The correlation functions between time series of concentrations of positive charges over the sea and gas bubbles averaged over a depth range from 0.4 to 4 m and wind speed are presented. There was zero lag between the cross-correlation maxima of charge and bubbles, but there was a phase lag of one and a half hours between charge and wind speed.
In the course of hyperbaric expositions divers undergo extremely stressful conditions. Insufficient compensatory mechanisms and/or inadequate procedure of decompression most frequently lead to the development of decompression sickness (DCS). The formation of gas bubbles in tissue is thought to be a key factor in the onset of DCS. However there are several reported cases of DCS in which gas bubbles could not be detected. Thus a predictive biochemical marker of increased risk of DCS is still much sought after. There is also no general agreement on the nature of reported changes in the number of circulating blood cells induced by diving and decompression. The aim of this study was to evaluate the effect of two different breathing mixtures used in simulated hyperbaric expositions on circulating blood cells and its predictive role in DCS risk assessment. 60 healthy divers underwent hyperbaric exposures at 0.7 MPa with 35 min plateau. 21 divers used air and the other group of 39 divers used trimix (pO2-0.04 MPa, pN2-0.08 MPa, pHe-0.71 MPa) as a breathing mixture. Total decompression time in both groups was 3 hours and 7 min. The following parameters were measured: erythrocyte, leukocyte, neutrophile, and platelet count, haematocrit, MPV, MCHC, MCV, CD61, CD62P expression on platelets, and microplatelets. Hyperbaric exposures and decompressions had a pronounced effect on platelets in the group using air as a breathing mixture contrary to the group using heliox as a breathing mixture where in fact the number of platelets decreased. There were also observed increased amounts of microplatelets in the group using air. CD62P expression in the air group increased after decompression whereas expression of CD61 was not affected in both groups of divers. We observed an increased number of leukocytes and neutrophiles in both groups of divers. Diving and decompression had no significant effect on the number of erythrocytes and their morphology in both groups. Conclusion: Measurements of platelet count, microplatelets as well as the expression of CD62P on platelets seem to be of importance in the assessment of the risk of DCS. The predictive role of the observed changes in leukocyte and neutrophile count after decompression should be further investigated.
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