This paper analyses simple models Drawing Tablet for "production-utilisation" systems, reduced to two state variables for producers and utilisers, respectively.Two modes are distinguished: in "harvester" systems the resource utilisation involves active seeking on the part of the utilisers, while in "processor" systems,
Abstract Background Sphaerophoria rueppellii, a European species of hoverfly, is a highly effective beneficial predator of hemipteran crop pests including aphids, thrips and coleopteran/lepidopteran larvae in integrated pest management (IPM) programmes.It is also a key pollinator of a wide variety of important agricultural crops.No genomic informat
Environmental sustainability is a burning fact worldwide, especially in developing nations.Equitable economic development, environmental protection, energy efficiency and security have been placed at the apex of economic discussant and policy formulation.This paper establishes the relationship between trade and environmental quality in Sub-Saharan