124 research outputs found

    Falciparum Malaria in European Tourists to the Dominican Republic

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    The Quantum Cosmological Wavefunction at Very Early Times for a Quadratic Gravity Theory

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    The quantum cosmological wavefunction for a quadratic gravity theory derived from the heterotic string effective action is obtained near the inflationary epoch and during the initial Planck era. Neglecting derivatives with respect to the scalar field, the wavefunction would satisfy a third-order differential equation near the inflationary epoch which has a solution that is singular in the scale factor limit a(t)0a(t)\to 0. When scalar field derivatives are included, a sixth-order differential equation is obtained for the wavefunction and the solution by Mellin transform is regular in the a0a\to 0 limit. It follows that inclusion of the scalar field in the quadratic gravity action is necessary for consistency of the quantum cosmology of the theory at very early times.Comment: Tex, 13 page

    Computing Optimal Tolls with Arc Restrictions and Heterogeneous Players

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    The problem of computing optimal network tolls that induce a Nash equilibrium of minimum total cost has been studied intensively in the literature, but mostly under the assumption that these tolls are unrestricted. Here we consider this problem under the more realistic assumption that the tolls have to respect some given upper bound restrictions on the arcs. The problem of taxing subnetworks optimally constitutes an important special case of this problem. We study the restricted network toll problem for both non-atomic and atomic (unweighted and weighted) players; our studies are the first that also incorporate heterogeneous players, i.e., players with different sensitivities to tolls. For non-atomic and heterogeneous players, we prove that the problem is NP-hard even for single-commodity networks and affine latency functions. We therefore focus on parallel-arc networks and give an algorithm for optimally taxing subnetworks with affine latency functions. For weighted atomic players, the problem is NP-hard already for parallel-arc networks and linear latency functions, even if players are homogeneous. In contrast, for unweighted atomic and homogeneous players, we develop an algorithm to compute optimal restricted tolls for parallel-arc networks and arbitrary (standard) latency functions. Similarly, for unweighted atomic and heterogeneous players, we derive an algorithm for optimally taxing subnetworks for parallel-arc networks and arbitrary (standard) latency functions. The key to most of our results is to derive (combinatorial) characterizations of flows that are inducible by restricted tolls. These characterizations might be of independent interest

    What determines the Czech land market prices? Some regional findings

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    The paper deals with the analysis of market land prices that were collected from land purchased contracts in the Czech Republic. Regression model was used to identify determinants explaining variability of market prices between 2008 and 2009. It was found out that type of plantation, region, type of buyers, plot size, distance to regional city or number of parcels play significant role. These factors explain more than a half of variance in land price. Quality of land that was expressed through administrative price has significant effect on market price. Yet, such effect became less import in regions nearby cities (e.g. Prague and Olomouc), where the market land price is significantly influenced by the distance to the district city. Land reform, however has not been confirmed to stimulate higher prices for sellers. It is reasonable to expect that part of the remaining variation could still be accounted for by non-random variables.Land, market price, administrative price, regression model, region., Land Economics/Use, GA, IN,

    Risk and Subsidies in Czech Agriculture - an ex-ante Analysis of Farmers´ Decision-making

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    This paper deals with the ex-ante analysis of the effects of farm subsidies on farm behaviour. Beside that the risk factor is implemented in the farm model to reflect and quantify potential (negative) impact on farm results. A farm-level optimization model is used to assess the effects of different kind of policies and risk on production structure, income indicators and land use management. It appeared that a reasonable level of risk (via income variation) have impact, but not significant. If liberalisation would have happened (zero direct and disadvantageous payments) production would homogenised, 30% of land would remained abandoned, production and income would clearly decline. Other scenario points out that environmental objectives (here through more extensively managed land) could not be necessarily more costly, but in such a case without accompanying livestock. To increase profitable livestock production requires to provide grassland and animal payments above the current level (obviously in addition to stimulating production economizing) whereas both payments should be conditional to each other.Agrarian policy, risk assessment, farm model, direct payments, Agricultural and Food Policy, Farm Management, GA, IN,

    Malarone treatment failure not associated with previously described mutations in the cytochrome b gene

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    Malarone(® )(atovaquone-proguanil) is an effective drug for the treatment and prophylaxis of multidrug-resistant falciparum malaria. However, first cases of resistance have been reported, which are associated with mutations at codon 268 of the parasite's cytochrome b gene. We report the first case of Malarone(® )treatment failure from Central Africa. Drug concentration was well within curative range. Pre- and post-treatment Plasmodium falciparum isolates revealed codon 268 wild-type alleles, and no other mutations of the putative atovaquone-binding domain. These findings illustrate the spread of atovaquone-proguanil-resistance in Africa and question the usefulness of codon 268 as the only target for the surveillance of its emergence

    Impact of public subsidies on farms’ technical efficiency in New Member States before and after EU accession

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    This paper presents some results of a two-year (2006-2007) research project supported by the French Ministry of Research’s funding program ECONET. One of the project’s objectives was to investigate the determinants of farm technical efficiency in New Member States before and after accession to the European Union, and in particular the role of public subsidies on this performance variable. Four countries were considered: Hungary, the Czech Republic and Slovenia, who acceded to the EU in 2004, and Romania, whose accession was in 2007. The study found that subsidies had a negative impact on farm technical efficiency in Hungary over the period 2001-2005, in the Czech dairy corporate sector over the period 2000-2004, in Slovenia over the period 1994-2003, and in the Romanian crop sector in 2005.technical efficiency, farms, subsidies, Hungary, Czech Republic, Slovenia, Romania, Farm Management,
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