10,526 research outputs found

    Global Welfare and Trade-Related Regulations of GM Food: Biosafety, Markets, and Politics

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    Replaced with revised version of paper 07/22/10.Genetically modified food, international trade, regulations, political economics., Agricultural and Food Policy, International Relations/Trade, Political Economy, Research and Development/Tech Change/Emerging Technologies, Q17, Q18, F50,

    Bounding errors of Expectation-Propagation

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    Expectation Propagation is a very popular algorithm for variational inference, but comes with few theoretical guarantees. In this article, we prove that the approximation errors made by EP can be bounded. Our bounds have an asymptotic interpretation in the number nn of datapoints, which allows us to study EP's convergence with respect to the true posterior. In particular, we show that EP converges at a rate of 0(n2)\mathcal{0}(n^{-2}) for the mean, up to an order of magnitude faster than the traditional Gaussian approximation at the mode. We also give similar asymptotic expansions for moments of order 2 to 4, as well as excess Kullback-Leibler cost (defined as the additional KL cost incurred by using EP rather than the ideal Gaussian approximation). All these expansions highlight the superior convergence properties of EP. Our approach for deriving those results is likely applicable to many similar approximate inference methods. In addition, we introduce bounds on the moments of log-concave distributions that may be of independent interest.Comment: Accepted and published at NIPS 201

    Biosafety at the crossroads: An analysis of South Africa's marketing and trade policies for genetically modified products

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    "South Africa is the only country in Africa that has both adopted genetically modified (GM) crops and developed a functional biosafety system to manage any risks related to the use of GM products. But it is also one of the only countries that trade both GM and non-GM crops, despite being surrounded by countries banning the use of GM products. In this paper, we analyze the marketing and trade policies for GM products in South Africa that have been successful in the past and critically review recent reforms to these policies. By providing trade volume estimates of potentially GM products, we show that South Africa is effectively a significant exporter and importer of both GM and non-GM products. We then show that although its import approval system has been effective, recent reforms have allowed regulators to use biosafety regulations as an apparent nontariff barrier to trade. On the export side, South Africa has been able to adapt to each specific demand, but potential export risks have gradually entered the decisionmaking process through the inclusion of socioeconomic considerations. On the marketing side, we show that although non-GM maize segregation has been successful so far, it has generated some adjustment costs and could be improved. At the same time, by excluding all current GM products, the GM food labeling regulation in place has not been fully satisfactory and is bound to change; it could be heading toward a strict mandatory system, despite limited public demand. Therefore, there is a clear movement toward more costly and rigid trade and marketing regulations for GM products in South Africa, with local special-interest groups having an increasing influence on decisionmaking. Yet, the past 10 years have demonstrated that South Africa's success in taking advantage of biotechnologies under changing global conditions stems mainly from its adaptation capacity and the flexibility of its system. Based on the analysis presented in this paper, we provide six policy recommendations to improve rather than rigidify market and trade regulations—policies that would allow South Africa to better adapt to global changes, to manage risks rigorously but efficiently, and to take advantage of safe and potentially promising new GM technologies." from authors' abstractTrade regulations, Genetically modified crops, Marketing, trade policies, Genetically modified products, Biosafety, Genetic resources, Science and technology,

    Fast Computation of Solvation Free Energies with Molecular Density Functional Theory: Thermodynamic-Ensemble Partial Molar Volume Corrections

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    Molecular Density Functional Theory (MDFT) offers an efficient implicit- solvent method to estimate molecule solvation free-energies whereas conserving a fully molecular representation of the solvent. Even within a second order ap- proximation for the free-energy functional, the so-called homogeneous reference uid approximation, we show that the hydration free-energies computed for a dataset of 500 organic compounds are of similar quality as those obtained from molecular dynamics free-energy perturbation simulations, with a computer cost reduced by two to three orders of magnitude. This requires to introduce the proper partial volume correction to transform the results from the grand canoni- cal to the isobaric-isotherm ensemble that is pertinent to experiments. We show that this correction can be extended to 3D-RISM calculations, giving a sound theoretical justifcation to empirical partial molar volume corrections that have been proposed recently.Comment: Version with correct equation numbers is here: http://compchemmpi.wikispaces.com/file/view/sergiievskyi_et_al.pdf/513575848/sergiievskyi_et_al.pdf Supporting information available online at: http://compchemmpi.wikispaces.com/file/view/SuppInf_sergiievskyi_et_al_07-04-2014.pdf/513576008/SuppInf_sergiievskyi_et_al_07-04-2014.pd

    From “May Contain” to “Does Contain”: The price and trade effects of strict information requirements for GM maize under the Cartagena Protocol on Biosafety

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    Replaced with revised version of paper 07/22/10.Genetically modified food, International Trade, Cartagena Protocol on Biosafety., Agricultural and Food Policy, Environmental Economics and Policy, International Relations/Trade, Political Economy, Research and Development/Tech Change/Emerging Technologies, Q17, Q18, F18,

    Marketing Underutilized Plant Species for the Poor

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    Underutilized plant species are defined as agricultural or non-timber forest species that are locally abundant in developing countries but globally rare. Scientific information about them is scant and their use is currently limited relative to their economic potential. Some are potentially high-value crops and they all contribute to agricultural biodiversity and the livelihood of the poor. Despite a growing body of scientific literature on underutilized species, to our knowledge, agricultural economics literature has contributed little to the understanding of how to commercialize these crops of plant products successfully. In this paper we first define what economic factors characterize underutilized plant species. Our classification of species is based on: 1) the relationship of the observed to the potential economic value of the species; 2) the presence or absence of an output market; and 3) the presence of market imperfections and 4) the presence of particular market failures. With this economic characterization, we exclude species for which developing markets is in or of itself irrelevant. We then identify three necessary conditions to the successful commercialization of underutilized plant species for the poor: demand expansion, increase efficiency of supply and supply control mechanism. The purpose of developing this simple conceptual framework is to provide a basis for the design of an empirical investigation of marketing solutions for underutilized plant species among the rural poor in developing economies.agricultural marketing, agricultural biodiversity, economic development, Crop Production/Industries, Q13, O13, Q56,
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