1,620 research outputs found

    MODELING INTERNATIONAL TRADE IMPACTS OF GENETICALLY MODIFIED WHEAT INTRODUCTIONS

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    Planned introductions of genetically modified crop varieties can be troublesome to model. Estimation of demand and supply equations is not feasible due to lack of data. Further, specifying demand and supply equations requires calibration to a presumed equilibrium. Depending on the point chosen, highly questionable results may be obtained. We propose a model that uses existing supply, demand, and elasticity estimates. The approach relies on composite supply and demand functions. These composite functions are linear combinations of GM and non-GM varieties. We then employ this approach in a model of world wheat trade to analyze the impact of several plausible GM wheat adoption and consumer acceptability scenarios.international trade, genetically modified organisms, producer surplus, consumer surplus, welfare, transportation cost, International Relations/Trade, Research and Development/Tech Change/Emerging Technologies,

    The Responses of Plankton Communities in Experimental Ponds to Atrazine, the Most Heavily Used Pesticide in the United States

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    Experimental ponds received single additions of the herbicide atrazine in concentrations of 20 and 500 gg/L, and were compared to control ponds for 136 d. Atrazine is an inhibitor of photosynthesis, and both concentrations depressed phytoplankton growth in the ponds within a few days. This was followed by successional changes leading to the establishment of species of phytoplankton more resistant to inhibition by atrazine. Laboratory studies verified this resistance and verified effects on other species at concentrations of atrazine as low as 1-5 Jig/L. When and to what extent resistant species appeared in the phytoplankton communities differed with treatment. At the atrazine concentration of 500 gg/L, there was a delayed appearance but eventually a greater biomass and persistence of these species. The grazing zooplankton influenced these differences and were in turn affected by them. Natural interactions such as competition and predation among the species of the communities greatly affected their responses to the toxic chemical. The importance of atrazine as an environmental pollutant is suggested by these responses to concentrations of 1-5 gg/L, which are common downstream in many agricultural watersheds, 20 /Ig/L, which is the high level found in these waters, and 500 gg/L, which is the high level found in waters directly adjacent to treated fields

    Enhanced structural correlations accelerate diffusion in charge-stabilized colloidal suspensions

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    Theoretical calculations for colloidal charge-stabilized and hard sphere suspensions show that hydrodynamic interactions yield a qualitatively different particle concentration dependence of the short-time self-diffusion coefficient. The effect, however, is numerically small and hardly accessible by conventional light scattering experiments. Applying multiple-scattering decorrelation equipment and a careful data analysis we show that the theoretical prediction for charged particles is in agreement with our experimental results from aqueous polystyrene latex suspensions.Comment: 1 ps-file (MS-Word), 14 page

    AGRICULTURAL VALUE ADDED: PROSPECTS FOR NORTH DAKOTA

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    Introduction: This report provides an overview of the important factors affecting investments in agricultural value-added ventures. The introductory section outlines current research on factors important in the location of economic activity. Research applied to specific agricultural value-added ventures, such as food manufacturing and livestock feeding and finishing operations, are discussed. A listing of resources available to entrepreneurs considering value-added investments concludes the introductory section. Following the introductory section are short overviews of industries that already have, or may have, potential for increasing economic activity in the state. All are based on the important foundation of agriculture in the state's economy or upon the natural resource base giving the state a comparative advantage in investments in alternative energy or resource-based recreation.Agribusiness,

    The Biological Standard of Living in the two Germanies.

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    Physical stature is used as a proxy for the biological standard of living in the two Germanies before and after unification in an analysis of a cross-sectional sample (1998) of adult heights, as well as among military recruits of the 1990s. West Germans tended to be taller than East Germans throughout the period under consideration. Contrary to official proclamations of a classless society, there were substantial social differences in physical stature in East-Germany. Social differences in height were greater in the East among females, and less among males than in the West. The difficulties experienced by the East-German population after 1961 is evident in the increase in social inequality of physical stature thereafter, as well as in the increasing gap relative to the height of the West-German population. After unification, however, there is a tendency for East-German males, but not of females, to catch up with their West-German counterparts

    Sustainability assessment of high voltage transmission lines

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    This work aims to contribute to the proposal of a multi-criteria based methodology for sustainability evaluation of impacts from high voltage transmission lines integrating indicators reflecting environmental and socio-economic criteria. The proposed methodology was applied to a transmission grid project in Manaus/Amazonas, Brazil, evaluating its sustainability. From the analysis, it can be observed that the implementation of the project tends to have a significant impact during the construction phase. The most important indexes come from the environmental dimension resulting from a proximity to environmental protected areas and reduction of vegetation both during implementation and operation phases, which is particularly important for the case of Amazonia forest. As for the socio-economic index, this reflects an optimistic expectation of the population towards the arrival of electricity to communities that can lead to the creation of more jobs and improvement of cities infrastructures along with the low expected impact on local protected communities, given the previous studies addressing these concerns during the design phase. Based on the results achieved, avenues for future research are proposed.This work is financed by the ERDF – European Regional Development Fund through the Oper ational Programme for Competitiveness and Internationalisation COMPETE 2020 Programme, and by National Funds through the Portuguese funding agency, FCT Fundação para a Ciência e a Tecnologia, within project SAICTPAC/0004/2015-POCI/01/0145/FEDER/016434.as well as by the ALGORITMI research Centre POCI-01-0145-FEDER-007043 and FCT – Fundação para a CiĂȘncia e Tecnologia within the Project Scope: UID/CEC/00319/2013

    A heterobivalent ligand inhibits mast cell degranulation via selective inhibition of allergen-IgE interactions in vivo

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    Current treatments for allergies include epinephrine and antihistamines, which treat the symptoms after an allergic response has taken place; steroids, which result in local and systemic immune suppression; and IgE-depleting therapies, which can be used only for a narrow range of clinical IgE titers. The limitations of current treatments motivated the design of a heterobivalent inhibitor (HBI) of IgE-mediated allergic responses that selectively inhibits allergen-IgE interactions, thereby preventing IgE clustering and mast cell degranulation. The HBI was designed to simultaneously target the allergen binding site and the adjacent conserved nucleotide binding site (NBS) found on the Fab of IgE Abs. The bivalent targeting was accomplished by linking a hapten to an NBS ligand with an ethylene glycol linker. The hapten moiety of HBI enables selective targeting of a specific IgE, whereas the NBS ligand enhances avidity for the IgE. Simultaneous bivalent binding to both sites provided HBI with 120-fold enhancement in avidity for the target IgE compared with the monovalent hapten. The increased avidity for IgE made HBI a potent inhibitor of mast cell degranulation in the rat basophilic leukemia mast cell model, in the passive cutaneous anaphylaxis mouse model of allergy, and in mice sensitized to the model allergen. In addition, HBI did not have any observable systemic toxic effects even at elevated doses. Taken together, these results establish the HBI design as a broadly applicable platform with therapeutic potential for the targeted and selective inhibition of IgE-mediated allergic responses, including food, environmental, and drug allergies

    Homogeneous nucleation of colloidal melts under the influence of shearing fields

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    We study the effect of shear flow on homogeneous crystal nucleation, using Brownian Dynamics simulations in combination with an umbrella sampling like technique. The symmetry breaking due to shear results in anisotropic radial distribution functions. The homogeneous shear rate suppresses crystal nucleation and leads to an increase of the size of the critical nucleus. These observations can be described by a simple, phenomenological extension of classical nucleation theory. In addition, we find that nuclei have a preferential orientation with respect to the direction of shear. On average the longest dimension of a nucleus is along the vorticity direction, while the shortest dimension is preferably perpendicular to that and slightly tilted with respect to the gradient direction.Comment: 10 pages, 8 figures, Submitted to J. Phys.: Condens. Matte
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