during a two-year (2004-2005) survey of alfalfa aphids and their natural enemies in isfahan, a total of four aphid species and 58 species of their natural enemies comprised of 45 predatory species, 11 parasitoid species and two species of parasitic mites were collected and identified. moreover, five hyperparasitoid species were collected. on each sampling date, six 20-sweep samples were taken u...

BACKGROUND Surgery for hip fracture carries a high risk of venous thromboembolism, despite the use of current thromboprophylactic treatments. Fondaparinux, a synthetic pentasaccharide, is a new antithrombotic agent that may reduce this risk. METHODS In a double-blind study, were randomly assigned 1711 consecutive patients undergoing surgery for fracture of the upper third of the femur to rece...

Imports are increasingly becoming a significant source of Japan’s pork supply. Japan’s share of imports to total consumption increased from 9 percent in 1980 to 24 percent in 1990, reaching a maximum of 44 percent in 1996. Under the World Trade Organization (WTO) safeguard provisions for pork, Japan can raise its gate price by 24 percent when imports in a given quarter are 119 percent higher th...

This paper is designed as an introduction to the two papers that follow. It opens with remarks about the nature of systems ecology before discussing its principal technique, systems modelling. This is followed by two simple agricultural examples and a brief discussion of the potential of systems modelling in ecology. More comprehensive treatments can be found in Walters (1971), Patten (1971), a...