Measurement and comparison of individual external doses of high-school students living in Japan, France, Poland and Belarus -- the "D-shuttle" project --

Twelve high schools in Japan (of which six are in Fukushima Prefecture), four in France, eight in Poland and two in Belarus cooperated in the measurement and comparison of individual external doses in 2014. In total 216 high-school students and teachers participated in the study. Each participant wore an electronic personal dosimeter "D-shuttle" for two weeks, and kept a journal of his/her whereabouts and activities. The distributions of annual external doses estimated for each region overlap with each other, demonstrating that the personal external individual doses in locations where residence is currently allowed in Fukushima Prefecture and in Belarus are well within the range of estimated annual doses due to the background radiation level of other regions/countries

Modèle mathématique de marées littorales. Calcul numérique sur l'exemple de la Manche

The authors review a few standard ideas on coastal tides for which they give a more restrictive definition than the generally accepted one. They set out the basic equations in standard form to within the friction terme, which is quadratic with respect to velocity. They oblain a quasi-linear system of partial differential equations of the hyperbolic type with non-analytical coefficients. With the theory of tides, this system becomes a composite problem which is still awaiting rigorous discussion. By extrapolation of data from simpler cases to this problem some of the properties of tides can be interpreted qualitatively and the digital methods applied for their calculation to some extent justified. The authors then describe their digital computation scheme for mean Channel tides, which is an application of the finite-difference method relying on a predetermined 'discretization' of the variation range of the unknowns. The mean tide given by the mathematical model reflects the real-life tide to within a satisfactory degree of approximation, also such specific properties as amphidrom of currents, high-tide persistence at Le Havre and the tide configuration in Saint-Malo Bay