1,679 research outputs found

    Onsager Relations and Hydrodynamic Balance Equations in 2D Quantum Wells

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    In this letter we clarify the role of heat flux in the hydrodynamic balance equations in 2D quantum wells, facilitating the formulation of an Onsager relation within the framework of this theory. We find that the Onsager relation is satisfied within the framework of the 2D hydrodynamic balance equation transport theory at sufficiently high density. The condition of high density is consonant with the requirement of strong electron-electron interactions for the validity of our balance equation formulation.Comment: 11 pages, RevTex, 4 postscript figures are avaliable upon reques

    Influence of Glomus etunicatum/Zea mays mycorrhiza on atrazine degradation, soil phosphatase and dehydrogenase activities, and soil microbial community structure

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    The effects of an arbuscular mycorrhizal (AM) fungus (Glomus etunicatum) on atrazine dissipation, soil phosphatase and dehydrogenase activities and soil microbial community structure were investigated. A compartmented side-arm ('cross-pot') system was used for plant cultivation. Maize was cultivated in the main root compartment and atrazine-contaminated soil was added to the side-arms and between them 650 or 37 mu m nylon mesh was inserted which allowed mycorrhizal roots or extraradical mycelium to access atrazine in soil in the side-arms. Mycorrhizal roots and extraradical mycelium increased the degradation of atrazine in soil and modified the soil enzyme activities and total soil phospholipid fatty acids (PLFAs). Atrazine declined more and there was greater stimulation of phosphatase and dehydrogenase activities and total PLFAs in soil in the extraradical mycelium compartment than in the mycorrhizal root compartment when the atrazine addition rate to soil was 5.0 mg kg(-1). Mycelium had a more important influence than mycorrhizal roots on atrazine degradation. However, when the atrazine addition rate was 50.0 mg kg(-1). atrazine declined more in the mycorrhizal root compartment than in the extraradical mycelium compartment, perhaps due to inhibition of bacterial activity and higher toxicity to AM mycelium by atrazine at higher concentration. Soil PLFA profiles indicated that the AM fungus exerted a pronounced effect on soil microbial community structure. (C) 2009 Elsevier Ltd. All rights reserved

    Parameter estimation for VSI-Fed PMSM based on a dynamic PSO with learning strategies

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    © 1986-2012 IEEE.A dynamic particle swarm optimization with learning strategy (DPSO-LS) is proposed for key parameter estimation for permanent magnet synchronous machines (PMSMs), where the voltage-source inverter (VSI) nonlinearities are taken into account in the parameter estimation model and can be estimated simultaneously with other machine parameters. In the DPSO-LS algorithm, a novel movement modification equation with variable exploration vector is designed to effectively update particles, enabling swarms to cover large areas of search space with large probability and thus the global search ability is enhanced. Moreover, a Gaussian-distribution-based dynamic opposition-based learning strategy is developed to help the pBest jump out local optima. The proposed DPSO-LS can significantly enhance the estimator model accuracy and dynamic performance. Finally, the proposed algorithm is applied to multiple parameter estimation including the VSI nonlinearities of a PMSM. The performance of DPSO-LS is compared with several existing PSO algorithms, and the comparison results show that the proposed parameters estimation method has better performance in tracking the variation of machine parameters effectively and estimating the VSI nonlinearities under different operation conditions

    Finding approximate palindromes in strings

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    We introduce a novel definition of approximate palindromes in strings, and provide an algorithm to find all maximal approximate palindromes in a string with up to kk errors. Our definition is based on the usual edit operations of approximate pattern matching, and the algorithm we give, for a string of size nn on a fixed alphabet, runs in O(k2n)O(k^2 n) time. We also discuss two implementation-related improvements to the algorithm, and demonstrate their efficacy in practice by means of both experiments and an average-case analysis

    Effect of substituting guinea grass with sunflower hulls on production performance and digestion traits in fattening rabbits

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    [EN] The objective of this study was to evaluate the use of sunflower hulls (SH) to substitute guinea grass (GG), traditionally used as a fibre source in the diets of fattening rabbits, on production performance, coefficients of total tract apparent digestibility (CTTAD) of nutrients, gastrointestinal tract development and caecal fermentation. A total of 160 mixed sex Hyla commercial meat rabbits were allocated to 4 experimental groups (40 per treatment) differing in the SH level inclusion in the diet offered to rabbits from 40 to 90 d of age: 0, 30, 60 and 90 g/kg on as-fed basis: SH0, SH30, SH60 and SH90 groups, respectively. Growth performance was recorded from 47 to 90 d of age, CTTAD of nutrients from 86 to 90 d of age, and gastrointestinal tract development, caecal fermentation and carcass traits were determined at 90 d of age. Increasing substitutions of SH in the diet indicated effects on growth performance, as higher feed intake and lower feed efficiency were observed in SH90 compared with SH0 (P-linear<0.05). Moreover, the higher SH substitution diet (SH60 and SH90) increased the relative caecum weight (P-linear<0.05). A linear negative effect of SH inclusion was observed for the digestibility of neutral detergent fibre (CTTAD from 0.294 to 0.232) and acid detergent fibre (CTTAD from 0.182 to 0.136; P-linear<0.05). Dietary SH substitution level had a quadratic effect on the villus height of the duodenum, jejunum and ileum obtained (P-quadratic<0.05), and the highest were observed in the SH60 group. There was a quadratic effect on the pH of caecum content (P-quadratic<0.05), and the lowest was 6.08 in SH30 group. The total volatil fatty acids increased linearly with increasing SH in diets (from 71.11 to 76.98 mmol/L; P-linear<0.05), and when dietary SH increased, the proportion of acetate tended to increase (P-linear<0.05), and the proportions of propionic and butyric were decreased (P-linear<0.05, respectively). Substitution of GG with SH had no effect on carcass characteristics and meat quality. The current work shows that SH can replace up to 60 g/kg in diets for fattening rabbits, with no adverse impact on aspects of production performance or digestion traits.This study was supported by the earmarked fund for Modern Agro-industry Technology Research System (CARS-43-B-1) and Funds of Shandong “Double Tops” Programme.Liu, G.; Sun, C.; Zhao, X.; Liu, H.; Wu, Z.; Li, F. (2018). Effect of substituting guinea grass with sunflower hulls on production performance and digestion traits in fattening rabbits. World Rabbit Science. 26(3):217-225. https://doi.org/10.4995/wrs.2018.9375SWORD21722526

    Duality between quantum symmetric algebras

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    Using certain pairings of couples, we obtain a large class of two-sided non-degenerated graded Hopf pairings for quantum symmetric algebras.Comment: 15 pages. Letters in Math. Phy., to appear soo
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