Understanding how environmental fluctuations affect population persistence is essential for predicting the ecological impacts of expected future increases in climate variability. However, two bodies of theory make opposite predictions about the effect of environmental variation on persistence. Single-species theory, common in conservation biology and population viability analyses, suggests that...

The Allee effect, or inverse density dependence at low population sizes, could seriously impact preservation and management of biological populations. The mounting evidence for widespread Allee effects has lately inspired theoretical studies of how Allee effects alter population dynamics. However, the recent mathematical models of Allee effects have been missing another important force prevalen...

abstract one of the important economic problems in arid and semi-arid regions is insufficient water for agricultural purposes as it is evident for other purposes. accordingly, sustainable management of water resources becomes an important challenge for policymakers. this study investigated water use planning based on the fluctuation of rainfall and the random nature of water resources in firoza...

population growth and the needs for protein and dairy products has urged policy makers to pay attention to efficiency policies in the livestock sector. the objective of this study is to survey the factors affecting the income of milk production, to calculate cattlemen’s technical efficiency and to determine the factors affecting the technical efficiency in the northern khorasan province. the re...

Extreme environmental phenomena such as major precipitation events manifestly exhibit spatial dependence. Max-stable processes are a class of asymptotically-justified models that are capable of representing spatial dependence among extreme values. While these models satisfy modeling requirements, they are limited in their utility because their corresponding joint likelihoods are unknown for mor...

We consider the energy-driven stochastic state vector reduction equation for the density matrix, which for pure state density matrices can be written in two equivalent forms. We use these forms to discuss the decoupling of the noise terms for independent subsystems, and to construct “environmental” stochastic density matrices whose time-independent expectations are the usual quantum statistical...

climate change phenomenon is an important environmental challenge of the world. increasing extension of greenhouse gases and remote relationship phenomena accelerate the speed f climate change. changes in precipitation level, drought occurrence and changes in the level of surface and groundwater resources are the recognized consequences of climate change. in order to study consequences of clima...