Sources and Sinks: A Stochastic Model of Evolution in Heterogeneous Environments

Sources and sinks: a stochastic model of evolution in heterogeneous environments.

We study evolution driven by spatial heterogeneity in a stochastic model of source-sink ecologies. A sink is a habitat where mortality exceeds reproduction so that a local population persists only due to immigration from a source. Immigrants can, however, adapt to conditions in the sink by mutation. To characterize the adaptation rate, we derive expressions for the first arrival time of adapted...

Single-Commodity Stochastic Network Design with Multiple Sources and Sinks

This paper examines the single-commodity stochastic network design problem with multiple sources and sinks. We characterize the structures of the optimal designs and compare with the deterministic counterparts. We do this primarily to understand what constitutes good robust network designs, but hope that the understanding can also be used to develop better heuristic algorithms than those availa...

Integrating Awareness Sources in Heterogeneous Collaboration Environments

Collaboration in heterogeneous environments involves dealing with variety of information sources that generate information that users need to be aware of. Users must be empowered to tailor the quality of awareness information. Heterogeneity of sources and media adversely affects the quality of group awareness. We propose a solution in terms of integrating the sources at the information level an...

Evolution in Heterogeneous and Random Environments

the innovation of a statistical model to estimate dependable rainfall (dr) and develop it for determination and classification of drought and wet years of iran

آب حاصل از بارش منبع تأمین نیازهای بی شمار جانداران به ویژه انسان است و هرگونه کاهش در کم و کیف آن مستقیماً حیات موجودات زنده را تحت تأثیر منفی قرار می دهد. نوسان سال به سال بارش از ویژگی های اساسی و بسیار مهم بارش های سالانه ایران محسوب می شود که آثار زیان بار آن در تمام عرصه های اقتصادی، اجتماعی و حتی سیاسی- امنیتی به نحوی منعکس می شود. چون میزان آب ناشی از بارش یکی از مولفه های اصلی برنامه ...