Coarse-Grained Model for Phospholipid/Cholesterol Bilayer

We construct a coarse-grained (CG) model for dipalmitoylphosphatidylcholine (DPPC)/cholesterol bilayers and apply it to large-scale simulation studies of lipid membranes. Our CG model is a two-dimensional representation of the membrane, where the individual lipid and sterol molecules are described by point-like particles. The effective intermolecular interactions used in the model are systematically derived from detailed atomic-scale molecular dynamics simulations using the Inverse Monte Carlo technique, which guarantees that the radial distribution properties of the CG model are consistent with those given by the corresponding atomistic system. We find that the coarse-grained model for the DPPC/cholesterol bilayer is substantially more efficient than atomistic models, providing a speed-up of approximately eight orders of magnitude. The results are in favor of formation of cholesterol-rich and cholesterol-poor domains at intermediate cholesterol concentrations, in agreement with the experimental phase diagram of the system. We also explore the limits of the novel coarse-grained model, and discuss the general validity and applicability of the present approach

The 1975 Iowa Corn Yield Test Report, District 4 Upland

Results of the Iowa Corn Yield Test are published to aid Iowa farmers in selecting corn varieties. This is the fifty-sixth consecutive year for the test

Insecticide use on vegetables in Ghana: Would GM seed benefit farmers?

"Tomato, cabbage, and garden egg (African eggplant, or Solanum aethiopicum) are important crops for small-scale farmers and migrants in the rural and peri-urban areas of Ghana. Genetic modification has the potential to alleviate poverty through combating yield losses from pests and diseases in these crops, while reducing health risks from application of hazardous chemicals. This ex ante study uses farm survey data to gauge the potential for adoption of genetically modified (GM) varieties, estimate the potential impact of adoption on farm profits, and highlight economic differences among the three crops. Farmers' expenditures on insecticides are below the economic optimum in all three crops, and the estimated function for damage abatement shows that insecticide amounts are significant determinants of cabbage yields only. Nonetheless, yield losses from pests and disease affect insecticide use. A stochastic budget analysis also indicates a higher rate of return to vegetable production with the use of resistant seeds relative to the status quo, even considering the technology transfer fee for GM seed. Non–insecticide users could accrue higher marginal benefits than current insecticide users. Comparing among vegetable crops with distinct economic characteristics provides a wider perspective on the potential impact of GM technology. Until now, GM eggplant is the only vegetable crop that has been analyzed in the peer-reviewed, applied economics literature. This is the first analysis that includes African eggplant." from authors' abstractBiotechnology Developing countries, Genetically modified crops, pesticides, Pests Management, eggplant, damage abatement, stochastic budget analysis,

Vegetable Production and Pesticide Use in Ghana: Would GM Varieties Have an Impact at the Farm Level?

The objective of this study is to evaluate pesticide use as an important factor affecting potential adoption and farm level impact of genetically modified (GM) vegetable varieties in Ghana. Tomato is the most consumed vegetable and a food security crop. Cabbage is a vegetable of growing importance but limited cultivation and is produced in urban areas. Garden egg is a native African crop of wide consumption and importance for rural economies. Farm level information was collected in randomly selected sites in southern and central regions of Ghana. Partial budget analysis shows that investments in pesticides are rather low, especially for tomato and garden egg. Analysis of production using an abatement framework shows that insecticide amounts are significant in determining cabbage output levels only. Rate of returns of GM seeds however can still be high. GM varieties would need to show not only a high abatement rate and a high yield potential but mainly an affordable price, to reduce total costs and induce adoption.Farm, Genetically Modified, Ghana, Tomato, Agricultural and Food Policy, Consumer/Household Economics, Environmental Economics and Policy, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Health Economics and Policy, International Relations/Trade, Marketing, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies,

Insecticide Use on Vegetables in Ghana: Would GM Seed Benefit Farmers?

Tomato, cabbage and garden egg (African eggplant, or Solanum Aethiopicum) are important crops for small-scale farmers and migrants in the rural and peri-urban areas of Ghana. Genetic modification (GM) has the potential to alleviate poverty through combating yield losses from pests and diseases in these crops, while reducing health risks from application of hazardous chemicals. This ex-ante study uses farm survey data to gauge the potential for adoption of genetically-engineered varieties, estimate the potential impact of adoption on farm profits, and highlight economic differences among the three crops. Farmer's expenditures on insecticides are below the economic optimum in all three crops, and the estimated function for damage abatement shows that insecticide amounts are significant determinants of cabbage yields only. Nonetheless, yield losses from the pests and diseases affect insecticide use. Stochastic budget analysis also indicates a higher rate of return to vegetable production with the use of resistant seeds relative to status quo, even considering the technology transfer fee for GM seeds. Non-insecticide users could accrue higher marginal benefits than current insecticide users. Comparing among vegetable crops with distinct economic characteristics provides a wider perspective on the potential impact of GM technology. Until now, GM eggplant is the only vegetable crop that has been analyzed in the peer-reviewed, applied economics literature. This is the first analysis that includes African eggplant.Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,