The environmental consequences of increasing human population size are dynamic and nonlinear, not passive and linear. The role of feedbacks, thresholds, and synergies in the interaction of population size and the environment are reviewed here, with examples drawn from climate change, acid deposition, land use, soil degradation, and other global and regional environmental issues. The widelyassum...

We present a stochastic two-population model that describes the migration and growth of semisedentary foragers and sedentary farmers along a river valley during the Neolithic transition. The main idea is that random migration and transition from a sedentary to a foraging way of life, and backwards, is strongly coupled with the local crop production and associated degradation of land. We derive ...

We present a stochastic two-population model that describes the migration and growth of semisedentary foragers and sedentary farmers along a river valley during the Neolithic transition. The main idea of this paper is that random migration and transition from a sedentary to a foraging way of life, and backwards, is strongly coupled with the local crop production and associated degradation of la...

BACKGROUND The Mega Acer Kit® (MAK) is a newly designed heated and humidified breathing circuit that warms fluid passing through the circuit lumen. In this study, we investigated the system's efficacy for the perioperative prevention of hypothermia and fluid warming. METHODS Ninety patients undergoing spinal surgery were enrolled in this study and randomly assigned to 3 groups based on the fl...

the earth is a stable feature but it is diminished due to different factors including: the extension and development of cities, emerging of villages and rural areas with the physical texture of cities, the spreading of industrial units and population growth, changing the patterns of land use and lack of good management. this paper is concerned with the global and national perspective of these p...