Darwin's Principle of Divergence explains sympatric speciation as gradual and directional. Contradicting evidence suggests that species' traits evolve saltationally. Here, we model coevolution in exploiter-victim systems. Victims (resource population) have heritable, mutable cue phenotypes with different levels of defense. Exploiters have heritable, mutable perceptual phenotypes. Our simulation...

I. Introduction The Immigration Reform and Control Act (IRCA) was enacted in 1986 in an effort to reduce illegal migration by fining those employers who hire unauthorized workers. At the same time, in order to recognize the commitment that many unauthorized workers had already made to the U.S. labor market, the General Legalization Program granted amnesty to approximately 1.7 million people who...

today? If there is still a need, how might we address it? To define multilevel security, we must first define security, which is “the combination of confidentiality (the prevention of the unauthorized disclosure of information), integrity (the prevention of the unauthorized amendment or deletion of information), and availability (the prevention of the unauthorized withholding of information).” ...

Network in which the unauthorised users are permitted to use vacant quotas of the authorized spectrum for their communication without interrupting the communications of the authorized Users is called Cognitive Radio Networks. But According to the spectrum heterogeneity phenomenon, for the unauthorized users Channel availability is variable, due to the licensed user’s activity. Due to this, it i...

invention of satellite and the use of it in the broadcasting technology ,evolved the broadcasting organizations activities. on one hand, it developed the scope of broadcasting geographically and to some extent solved the limitations and problems of transmitting signals such as difficulties in receiving the signals in mountainous or wood areas. on the other hand, the use of satellites on transmi...