3,984 research outputs found

    Evaluation of Waterhyacinth and Paddy Straw Waste for Culture of Oyster Mushrooms

    Get PDF
    Waterhyacinth ( Eichhornia crassipes (Mart.) Solms.) was evaluated at ratios of 25, 50 and 75% with paddy straw ( Oryza sativa L.) for oyster mushroom ( Pleurotus sajor-caju) cultivation. There was an increase in yield with decreasing ratio waterhyacinth

    Approaching multichannel Kondo physics using correlated bosons: Quantum phases and how to realize them

    Full text link
    We discuss how multichannel Kondo physics can arise in the setting of a localized level coupled to several bosonic Tomonaga-Luttinger liquid leads. We propose one physical realization involving ultracold bosonic atoms coupled to an atomic quantum dot, and a second, based on superconducting nanowires coupled to a Cooper-pair box. The corresponding zero-temperature phase diagram is determined via an interplay between Kondo-type phenomena arising from the dot and the consequences of direct inter-lead hopping, which can suppress the Kondo effect. We demonstrate that the multichannel Kondo state is stable over a wide range of parameters. We establish the existence of two nontrivial phase transitions, involving a competition between Kondo screening at the dot and strong correlations either within or between the leads (which respectively promote local number- and phase-pinning). These transitions coalesce at a self-dual multicritical point.Comment: 5 pages, 4 figure

    Fate of global superconductivity in arrays of long SNS junctions

    Full text link
    Normal-metal films overlaid with arrays of superconducting islands undergo Berezinskii-Kosterlitz-Thouless (BKT) superconducting transitions at a temperature TBKTT_{BKT}. We present measurements of TBKT_{BKT} for arrays of mesoscopic Nb islands patterned on Au films for a range of island spacings dd. We show that TBKT1/d2T_{BKT} \sim 1/d^2, and explain this dependence in terms of the quasiclassical prediction that the Thouless energy, rather than the superconducting gap, governs the inter-island coupling. We also find two deviations from the quasiclassical theory: (i) TBKTT_{BKT} is sensitive to island height, because the islands are mesoscopic; and (ii) for widely spaced islands the transition appears to lead, not to a superconducting state, but to a finite-resistance "metallic" one.Comment: 12 pages, 4 figure

    Length control of microtubules by depolymerizing motor proteins

    Get PDF
    In many intracellular processes, the length distribution of microtubules is controlled by depolymerizing motor proteins. Experiments have shown that, following non-specific binding to the surface of a microtubule, depolymerizers are transported to the microtubule tip(s) by diffusion or directed walk and, then, depolymerize the microtubule from the tip(s) after accumulating there. We develop a quantitative model to study the depolymerizing action of such a generic motor protein, and its possible effects on the length distribution of microtubules. We show that, when the motor protein concentration in solution exceeds a critical value, a steady state is reached where the length distribution is, in general, non-monotonic with a single peak. However, for highly processive motors and large motor densities, this distribution effectively becomes an exponential decay. Our findings suggest that such motor proteins may be selectively used by the cell to ensure precise control of MT lengths. The model is also used to analyze experimental observations of motor-induced depolymerization.Comment: Added section with figures and significantly expanded text, current version to appear in Europhys. Let

    Gas permeation through a polymer network

    Full text link
    We study the diffusion of gas molecules through a two-dimensional network of polymers with the help of Monte Carlo simulations. The polymers are modeled as non-interacting random walks on the bonds of a two-dimensional square lattice, while the gas particles occupy the lattice cells. When a particle attempts to jump to a nearest-neighbor empty cell, it has to overcome an energy barrier which is determined by the number of polymer segments on the bond separating the two cells. We investigate the gas current JJ as a function of the mean segment density ρ\rho, the polymer length \ell and the probability qmq^{m} for hopping across mm segments. Whereas JJ decreases monotonically with ρ\rho for fixed \ell, its behavior for fixed ρ\rho and increasing \ell depends strongly on qq. For small, non-zero qq, JJ appears to increase slowly with \ell. In contrast, for q=0q=0, it is dominated by the underlying percolation problem and can be non-monotonic. We provide heuristic arguments to put these interesting phenomena into context.Comment: Dedicated to Lothar Schaefer on the occasion of his 60th birthday. 11 pages, 3 figure
    corecore