2,037 research outputs found

    Improving Forage Production on Claypan Soils

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    Mechanical range improvement practices such as contour ripping and furrowing have been used to increase forage production on a variety of range sites in the northern Great Plains. These improvement practices seem to have particular promise on Claypan and Thin Claypan range sites in western South Dakota. Soils on these range sites have a sodium dispersed layer (claypan) at or near the surface. This layer severely reduces the rate of water infiltration, thus causing a greater amount of the precipitation to run off or pool up and evaporate from the soil surface than would happen on soils of similar texture without the claypan layer. Because more precipitation water is lost to runoff and evaporation, less water is available for plant growth. The compact nature of the claypan layer also tends to restrict root growth, further reducing plant growth. Thus, claypan soils are inherently lower in forage production potential than similar soils without the claypan layer. The difference between productivity of the claypan soils and normal soils represents the potential increase in forage production if the effects of the claypan layer could somehow be removed

    Cool Season Grass Variety Comparisons in Jackson County

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    The purpose of the plant nursery trial in Jackson County, South Dakota, was to (1) provide information for landowners on planting a special use pasture for grazing or hay production, (2) assimilate longterm comparative yield and longevity data to support seeding reconmendations and (3) provide a visual comparison of sufficient size plantings for area residents, agency technicians and others to observe growth and survival characteristics of various grasses

    Cool Season Grass Variety Comparisons in Harding County

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    The purpose of the plant nursery trial in northwestern South Dakota was to (1) proivde information for landowners on planting a special use pasture for grazing or hay production; (2) assimilate long term comparative yield and longevity data to support seeding recommendations; and (3) provide a visual comparison of sufficient size plantings for area residents, agency technicians, and others to observe growth and survival characteristics of various grasses

    Band gap bowing of binary alloys: Experimental results compared to theoretical tight-binding supercell calculations for CdZnSe

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    Compound semiconductor alloys of the type ABC find widespread applications as their electronic bulk band gap varies continuously with x, and therefore a tayloring of the energy gap is possible by variation of the concentration. We model the electronic properties of such semiconductor alloys by a multiband tight-binding model on a finite ensemble of supercells and determine the band gap of the alloy. This treatment allows for an intrinsic reproduction of band bowing effects as a function of the concentration x and is exact in the alloy-induced disorder. In the present paper, we concentrate on bulk CdZnSe as a well-defined model system and give a careful analysis on the proper choice of the basis set and supercell size, as well as on the necessary number of realizations. The results are compared to experimental results obtained from ellipsometric measurements of CdZnSe layers prepared by molecular beam epitaxy (MBE) and photoluminescence (PL) measurements on catalytically grown CdZnSe nanowires reported in the literature.Comment: 7 pages, 6 figure

    Progression of neurovisceral storage disease with supranuclear ophthalmoplegia following orthotopic liver transplantation

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    A 7-year-old girl with progressive ataxia, spasticity, supranuclear ophthalmoplegia, and sea-blue histiocytes in her bone marrow underwent orthotopic liver transplantation for hepatocellular carcinoma. After an initial period of stabilization, she has shown progression of neurologic symptoms with recurrence of storage material in the transplanted liver

    Dispersion force for materials relevant for micro and nanodevices fabrication

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    The dispersion (van der Waals and Casimir) force between two semi-spaces are calculated using the Lifshitz theory for different materials relevant for micro and nanodevices fabrication, namely, gold, silicon, gallium arsenide, diamond and two types of diamond-like carbon (DLC), silicon carbide, silicon nitride and silicon dioxide. The calculations were performed using recent experimental optical data available in the literature, usually ranging from the far infrared up to the extreme ultraviolet bands of the electromagnetic spectrum. The results are presented in the form of a correction factor to the Casimir force predicted between perfect conductors, for the separation between the semi-spaces varying from 1 nanometre up to 1 micrometre. The relative importance of the contributions to the dispersion force of the optical properties in different spectral ranges is analyzed. The role of the temperature for semiconductors and insulators is also addressed. The results are meant to be useful for the estimation of the impact of the Casimir and van der Waals forces on the operational parameters of micro and nanodevices

    How to Educate Entrepreneurs?

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    Entrepreneurship education has two purposes: To improve studentsā€™ entrepreneurial skills and to provide impetus to those suited to entrepreneurship while discouraging the rest. While entrepreneurship education helps students to make a vocational decision its effects may conflict for those not suited to entrepreneurship. This study shows that vocational and the skill formation effects of entrepreneurship education can be identified empirically by drawing on the Theory of Planned Behavior. This is embedded in a structural equation model which we estimate and test using a robust 2SLS estimator. We find that the attitudinal factors posited by the Theory of Planned Behavior are positively correlated with studentsā€™ entrepreneurial intentions. While conflicting effects of vocational and skill directed course content are observed in some individuals, overall these types of content are complements. This finding contradicts previous results in the literature. We reconcile the conflicting findings and discuss implications for the design of entrepreneurship courses

    Interplay between Structure and Dynamics in Chitosan Films Investigated with Solid-State NMR, Dynamic Mechanical Analysis, and X-ray Diffraction

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    Modern solid-state NMR techniques, combined with X-ray diffraction, revealed the molecular origin of the difference in mechanical properties of self-associated chitosan films. Films cast from acidic aqueous solutions were compared before and after neutralization, and the role of the counterion (acetate vs Clā») was investigated. There is a competition between local structure and long-range order. Hydrogen bonding gives good mechanical strength to neutralized films, which lack long-range organization. The long-range structure is better defined in films cast from acidic solutions in which strong electrostatic interactions cause rotational distortion around the chitosan chains. Plasticization by acetate counterions enhances long-range molecular organization and film flexibility. In contrast, Clā» counterions act as a defect and impair the long-range organization by immobilizing hydration water. Molecular motion and proton exchange are restricted, resulting in brittle films despite the high moisture content

    Systemic Risk and Default Clustering for Large Financial Systems

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    As it is known in the finance risk and macroeconomics literature, risk-sharing in large portfolios may increase the probability of creation of default clusters and of systemic risk. We review recent developments on mathematical and computational tools for the quantification of such phenomena. Limiting analysis such as law of large numbers and central limit theorems allow to approximate the distribution in large systems and study quantities such as the loss distribution in large portfolios. Large deviations analysis allow us to study the tail of the loss distribution and to identify pathways to default clustering. Sensitivity analysis allows to understand the most likely ways in which different effects, such as contagion and systematic risks, combine to lead to large default rates. Such results could give useful insights into how to optimally safeguard against such events.Comment: in Large Deviations and Asymptotic Methods in Finance, (Editors: P. Friz, J. Gatheral, A. Gulisashvili, A. Jacqier, J. Teichmann) , Springer Proceedings in Mathematics and Statistics, Vol. 110 2015
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