Another World Food Scare?
Food's Frontier The Next Green Revolution. Richard Manning. North Point (Farrar, Straus, and Giroux), New York, 2000. 233 pp. $24, C$38.95. ISBN 0-86547-593-8. Manning argues that we have reached the limits of what the Green Revolution of the 1960s can do to supply food to a still growing world population. He discusses nine ongoing projects that are experimenting with potential means of further increases in food production, including indigenous knowledge, native crops, and biotechnology.
The World Food Problem: Four Recent Empirical Studies
T HE PURPOSE of this note is to compare the methodology and projections of four recent studies of world food trends. The focus is upon food demand and supply in the developing countries. The Food and Agriculture Organization of the United Nations (FAO) report, Agricultural Commodities-Projections for 1975 and 1985 [15], was an exhaustive base study. It stressed the importance of concessional food shipments and the potential for increased trade of agricultural commodities among developing countries. Since many developing countries are presently striving for some degree of self-sufficiency in food production [17, p. 22], the potential for food aid and increased food trade appears to be much less promising than depicted by FAO. The Organization for Economic Cooperation and Development (OECD) report, The Food Problem of Developing Countries [11], focused on developmental assistance. It asserted that agricultural commercialization is a capital intensive process; consequently, the capital shortages and generally unfavorable man-land ratios in the developing countries give them little potential for agricultural modernization. It argued that the comparative advantage of most underdeveloped countries in international trade is in labor-intensive manufacturing. Its focus on the necessity for a capital intensive agricultural sector ignores the labor intensive agricultural development process in both Japan and Taiwan [6, 7]. The stress on man-land ratios similarly ignores the potential of inputs such as the combination of fertilizer and fertilizer-responsive seed varieties to substitute for land. Also, the assumption that developing countries will have increasing access to the markets of developed countries to sell their manufactured goods appears implausible. The President's Science Advisory Committee (PSAC) report, The World Food Problem: A Report of the Panel on the World Food Supply
Properties of a monopivot centrifugal blood pump manufactured by 3D printing
An impeller the same geometry as the impeller of a commercial monopivot cardiopulmonary bypass pump was manufactured using 3D printing. The 3D-printed impeller was integrated into the pump casing of the commercially available pump to form a 3D-printed pump model. The surface roughness of the impeller, the hydraulic performance, the axial displacement of the rotating impeller, and the hemolytic properties of the 3D-printed model were measured and compared with those of the commercially available model. Although the surface roughness of the 3D-printed model was significantly larger than that of the commercially available model, the hydraulic performance of the two models almost coincided. The hemolysis level of the 3D-printed model roughly coincided with that of the commercially available model under low-pressure head conditions, but increased greatly under high-pressure head conditions, as a result of the narrow gap between the rotating impeller and the pump casing. The gap became narrow under high-pressure head conditions, because the axial thrust applied to the impeller increased with increasing impeller rotational speed. Moreover, the axial displacement of the rotating impeller was twice that of the commercially available model, confirming that the elastic deformation of the 3D-printed impeller was larger than that of the commercially available impeller. These results suggest that trial models manufactured by 3D printing can reproduce the hydraulic performance of the commercial product. However, both the surface roughness and the deformation of the trial models must be considered to precisely evaluate the hemolytic properties of the model.