Mathematical models are used to determine if infection wave fronts could occur by traveling geographically in a loop around a region or continent. These infectionwave fronts arise by Hopf bifurcation for some spatial models for infectious disease transmission with distributed-contacts. Periodic traveling waves are shown to exist for the spatial analog of the SIRS endemic model, in which the tem...

introduction the exposure of human beings to ionizing radiation from natural sources is a continuing and inescapable feature of life on earth. for most individuals, this exposure exceeds that from all man-made sources combined. materials and methods in this study, the annual effective dose in high level environmental background radiation areas (hlebras) of northern city of ramsar in iran was de...

The potential threats to the USA from current and projected sea level rise are significant, with profound environmental, social economic consequences. This study continues refinement improvement in analysis techniques for research beyond Fourth US National Climate Assessment (NCA4) report by incorporating further advancements time series of long tide gauge records integrated an improved vertica...