6,974 research outputs found

    Importance of appropriate selection environments for breeding maize adapted to organic farming systems

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    Organic farming systems, characterized by special attention to soil fertility, recycling techniques and low external inputs, gained increased significance in recent years. As a consequence, there is a growing demand for varieties adapted to organic and/or low input farming. The objectives of the present study were to (i) compare the testcross performance of segregating maize (Zea mays) populations under established organic (OF) and conventional farming (CF) systems, (ii) determine quantitative genetic parameters decisive for the selection response under OF vs CF conditions, and (iii) draw conclusions for breeding new varieties optimally adapted to OF. Testcross performance of four different material groups of preselected lines (90 lines per group) derived from early European breeding material was assessed under OF and CF in three different geographic regions in Germany in 2008. Grain yields under OF were 3 to 18% lower than under CF in the individual experiments depending on the test region and, to a lesser extent, on the genetic material. On average, grain dry matter yield under OF was 1077 g m-2 compared to 1186 g m-2 under CF. Phenotypic correlations between OF and CF were small or moderate for grain yield in each of the four material groups (0.22 to 0.45), while strong and highly significant correlations were found for dry matter content (0.89 to 0.94). Genotypes with top grain yields under OF often did not show this superiority under CF and vice versa. Despite considerable heterogeneity of the OF test sites, the heritability for grain yield was in the same order of magnitude under OF and CF. It is concluded that test sites managed by OF are indispensable for making maximum progress in developing maize varieties for these conditions

    Extended trigonometric Cherednik algebras and nonstationary Schr\"odinger equations with delta-potentials

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    We realize an extended version of the trigonometric Cherednik algebra as affine Dunkl operators involving Heaviside functions. We use the quadratic Casimir element of the extended trigonometric Cherednik algebra to define an explicit nonstationary Schr\"odinger equation with delta-potential. We use coordinate Bethe ansatz methods to construct solutions of the nonstationary Schr\"odinger equation in terms of generalized Bethe wave functions. It is shown that the generalized Bethe wave functions satisfy affine difference Knizhnik-Zamolodchikov equations in their spectral parameter. The relation to the vector valued root system analogs of the quantum Bose gas on the circle with pairwise delta-function interactions is indicated.Comment: 23 pages; Version 2: expanded introduction and misprints correcte

    Liquid Oxygen Liquid Acquisition Device Bubble Point Tests with High Pressure LOX at Elevated Temperatures

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    When transferring propellant in space, it is most efficient to transfer single phase liquid from a propellant tank to an engine. In earth s gravity field or under acceleration, propellant transfer is fairly simple. However, in low gravity, withdrawing single-phase fluid becomes a challenge. A variety of propellant management devices (PMD) are used to ensure single-phase flow. One type of PMD, a liquid acquisition device (LAD) takes advantage of capillary flow and surface tension to acquire liquid. The present work reports on testing with liquid oxygen (LOX) at elevated pressures (and thus temperatures) (maximum pressure 1724 kPa and maximum temperature 122K) as part of NASA s continuing cryogenic LAD development program. These tests evaluate LAD performance for LOX stored in higher pressure vessels that may be used in propellant systems using pressure fed engines. Test data shows a significant drop in LAD bubble point values at higher liquid temperatures, consistent with lower liquid surface tension at those temperatures. Test data also indicates that there are no first order effects of helium solubility in LOX on LAD bubble point prediction. Test results here extend the range of data for LOX fluid conditions, and provide insight into factors affecting predicting LAD bubble point pressures

    Palladium-Catalyzed Methylation of Aryl, Heteroaryl, and Vinyl Boronate Esters.

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    A method for the direct methylation of aryl, heteroaryl, and vinyl boronate esters is reported, involving the reaction of iodomethane with aryl-, heteroaryl-, and vinylboronate esters catalyzed by palladium and PtBu2Me. This transformation occurs with a remarkably broad scope and is suitable for late-stage derivatization of biologically active compounds via the boronate esters. The unique capabilities of this method are demonstrated by combining carbon-boron bond-forming reactions with palladium-catalyzed methylation in a tandem transformation

    An assessment of the effects of the 2002 food crisis on children's health in Malawi

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    In 2002 Malawi experienced a serious shortage of cereals due to adverse climatic conditions. The World Food Programme assumed that about 2.1 to 3.2 million people were threatened of starvation at that time. However, not much research has been undertaken to investigate the actual consequences of this crisis. In particular, little is known about how the crisis affected the health status of children. Obviously, quantifying the health impact of such a crisis is a serious task given the lack of data and the more general problem of relating outcomes to specific shocks and policies. In this paper a difference-in-difference estimator is used to quantify the impact of the food crisis on the health status of children. The findings suggest that at least in the short run, there was neither a significant impact on child mortality nor on malnutrition. This would suggest that the shock might have been less severe than initially assumed and that the various policy interventions undertaken at the time have been effective or at least sufficient to counteract the immediate effects of the crisis

    An assessment of the effects of the 2002 food crisis on children's health in Malawi

    Get PDF
    In 2002 Malawi experienced a serious shortage of cereals due to adverse climatic conditions. The World Food Programme assumed that about 2.1 to 3.2 million people were threatened of starvation at that time. However, not much research has been undertaken to investigate the actual consequences of this crisis. In particular, little is known about how the crisis affected the health status of children. Obviously, quantifying the health impact of such a crisis is a serious task given the lack of data and the more general problem of relating outcomes to specific shocks and policies. In this paper a difference-in-difference estimator is used to quantify the impact of the food crisis on the health status of children. The findings suggest that at least in the short run, there was neither a significant impact on child mortality nor on malnutrition. This would suggest that the shock might have been less severe than initially assumed and that the various policy interventions undertaken at the time have been effective or at least sufficient to counteract the immediate effects of the crisis

    Monoidal Hom-Hopf algebras

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    Hom-structures (Lie algebras, algebras, coalgebras, Hopf algebras) have been investigated in the literature recently. We study Hom-structures from the point of view of monoidal categories; in particular, we introduce a symmetric monoidal category such that Hom-algebras coincide with algebras in this monoidal category, and similar properties for coalgebras, Hopf algebras and Lie algebras.Comment: 25 pages; extended version: compared to the version that appeared in Comm. Algebra, the Section Preliminary Results and Remarks 5.1 and 6.1 have been adde

    Hom-Lie color algebra structures

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    This paper introduces the notion of Hom-Lie color algebra, which is a natural general- ization of Hom-Lie (super)algebras. Hom-Lie color algebras include also as special cases Lie (super) algebras and Lie color algebras. We study the homomorphism relation of Hom-Lie color algebras, and construct new algebras of such kind by a \sigma-twist. Hom-Lie color admissible algebras are also defined and investigated. They are finally classified via G-Hom-associative color algebras, where G is a subgroup of the symmetric group S_3.Comment: 16 page
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