The ionizing spectral energy distribution of quasars exhibits a steepening of the distribution short-ward of 1200 Å. The change of the power-law index from approximately −1 to −2 so far has been interpreted as being intrinsic to quasars. We study an alternative interpretation, in which a tenuous absorption screen is responsible for the change of index. We find that the most successful function ...

We propose a variant of hybrid inflation which is applicable in a wide class of supersymmetric grand unified models. The observed temperature perturbations of cosmic background radiation can be reproduced with natural values of the parameters of the theory and a grand unification scale which is consistent with the unification of the minimal supersymmetric standard model gauge couplings as measu...

In order to draw out the essential behavior of the universe, investigations of early universe cosmology often reduce the complex system to a simple integrable system. Inflationary models are of this kind as they focus on simple scalar field scenarios with correspondingly simple dynamics. However, we can be assured that the universe is crowded with many interacting fields of which the inflaton i...

methods in this article we checked the derived data from 20 relevant studies published during the last 20 years in international scientific literature at other country except iran and 10 studies from iran. the variables dose-area product (dap), fluoroscopy time, number of sequences and frames per sequence were collected for each ca, ptca, rfa and diagnostic electrophysiology and then the obtain...

 ABSTRACTBackground: There are relatively rich uranium mines in regions of Saghand and Bafgh in Yazd province. This survey was carried out to provide a map of ambient gamma radiation of Yazd province and the probable effects of the existence of these mines on background radiation dose rates.Materials and Methods: The measurements of the outdoor and indoor–environmental exposures (including cosm...

Introduction: Background radiation is originated from environmental radioactive sources cosmicandterrestrial.Materials distribution onsurface of the earth and height from sea level are not the same at various points.Absorbed dose caused by them were different at various points.In this research, Background radiation level inoutdoor different areas of Ilam province was measured and effective dose...