Notions of beauty have evolved through history and are culture-specific. In the Western world one concept which has been linked to beauty is that of kalokagathía, an ideal that unites physical beauty and moral value in a human being. This notion was inherited from Antiquity and was modified during the Middle Ages, when much more attention was paid to the fate of the soul, and further modified d...

We now consider the problem of the appearance of a black hole formed by a collapsing star. Our interest today lies entirely with the appearance of the star long after its collapse, or alternatively of the radiation emitted as the star crosses the Schwarzschild radius. We first show that in geometric optics, the surface of the doomed star remains forever visible with exponentially decreasing bri...

many reports that appeared during the last 20 years have shown that atmospheric pollution causes serious damage to human health and to environment. electricity generation from fuel fossil is one of the major sources of pollution and considerable share of this damage. the price of electricity in iran, as in many other countries also, includes only the production of private costs and ignores any ...

haft-peykar (or bahram-nameh) is the fourth nizami’s verse composition in terms of time and one of his masterpieces besides his khosrow and shirin. haft-peykar consists of two general parts: the first part is about bahram and his life and the second one is about the stories of his seven wives. the structure of the book makes it possible to be criticized through a formalistic approach. the chara...

social incentives that bring them into existence and sustain them in the course of time. Non-governmental organizations (NGOs), whether based in the global north or south, are not different. Unfortunately, numerous NGOs start up and then fail, because the passion of the founder is not supported by a sustainable organization Volunteers in all sectors are working with NGOs. The NGOs are citizen...