On the longitudinal structure of the transient day-to-day variation of the semidiurnal tide in the mid-latitude lower thermosphere - I. Winter season

The longitudinal structure of the day-to-day variations of semidiurnal tide amplitudes is analysed based on coordinated mesosphere/lower thermosphere wind measurements at several stations during three winter campaigns. Possible excitation sources of these variations are discussed. Special attention is given to a nonlinear interaction between the semidiurnal tide and the day-to-day mean wind variations. Data processing includes the S-transform analysis which takes into account transient behaviour of secondary waves. It is shown that strong tidal modulations appear during a stratospheric warming and may be caused by aperiodic mean wind variations during this event

Risk assessment for indoor exposure to radon daughters.

Approaches to and results for the estimation of healths risks from indoor exposure to radon and its daughter products are discussed. Particular weight is given to the derivation of exposure-time-effect relationships using a modified proportional hazard model which has been adapted to account for relevant epidemiological data. The results of this analysis indicate that about (10 ± 5) % of the lung cancer rate observed in the general public might be correlated to the enhanced exposure to radon daughters in dwellings (at 10 - 20 Bq/m3 (Rn-eq) and in outdoor air. A chronic exposure to indoor Rn-levels at home of about 300 - 500 Bq/m3 (Rn-eq) might possibly double the normal lung cancer rates. The relative fractions of radiogenic lung cancer rates might be nearly the same for smokers and non-smokers, and for men and women