Observational Test for a Random Sweeping Model in Solar Wind Turbulence.

Evidence of frequency broadening at ion kinetic scales due to large-scale eddies and waves is found in solar wind turbulence by a test for a random sweeping model using the magnetic energy spectrum in the frequency vs wave number domain in the comoving frame of the flow obtained from multispacecraft observations. The statistical analysis of the frequency vs wave number spectra without using Taylor's hypothesis shows Gaussian frequency broadening around nearly zero frequencies that increases for larger wave numbers and non-Gaussian tails at higher frequencies. Comparison of the observed frequency broadening with a random sweeping model derived from hydrodynamic turbulence reveals similarities with respect to the Gaussian shape. The standard deviation of the broadening scales with ∼k^{1.6±0.2} and differs from the hydrodynamic turbulence model that predicts ∼k^{2/3}. We interpret this stronger increasing broadening as a consequence of the more diverse large scale structures (eddies and waves) in plasma turbulence and the accompanied more complex sweeping. Consequently, an identification and association of waves with normal modes based on their dispersion relation only, in particular at ion kinetic scales and below, is not possible in solar wind turbulence.

The status of iodine nutrition in newborn infants, schoolchildren, adolescents and adults in former East Germany.

In the former East Germany (GDR) like in the former West Germany (FRG) iodine deficiency and endemic goiter have been described since more than 2 decades. After a program of salt iodization which was started in East Germany in 1985 the urinary iodine excretion of the population increased significantly. The thyroid gland of the newborn is much more sensible to changes of the iodine supply than the thyroid of older children. A total of 1732 subjects was enrolled in the study. After the implementation of the mandatory salt iodization the goiter prevalence in newborns decreased markedly to less than 1%. After the reunification of Germany in 1990 the mandatory prophylaxis was stopped and the urinary iodine excretion in newborns, school-children, adolescents and adults diminished markedly. So in newborns the renal iodine excretion decreased to 2.82 micrograms I/dl in 1992. Since 1994 a reasonable improvement of the iodine supply is observed in the region of Leipzig. In school-children, adolescents and adults the mean value of the urinary iodine excretion is now above 10.0 micrograms I/dl. This value may be considered as an indicator for a normal iodine supply. In a small cohort (n = 28) of newborns infants we found a renal iodine excretion of 18.74 micrograms/dl in 1997. That value also means a significant increase since 1992 and a normal iodine supply in the fetal period. The present results from the region of Leipzig/Saxonia are not representative for the whole of East Germany. To provide an optimal iodine nutrition the use of iodized salt for food manufacturing must be significantly increased.