19,099 research outputs found

    Strong Shift Equivalence of CC^*-correspondences

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    We define a notion of strong shift equivalence for CC^*-correspondences and show that strong shift equivalent CC^*-correspondences have strongly Morita equivalent Cuntz-Pimsner algebras. Our analysis extends the fact that strong shift equivalent square matrices with non-negative integer entries give stably isomorphic Cuntz-Krieger algebras.Comment: 26 pages. Final version to appear in Israel Journal of Mathematic

    C*-algebras of labelled graphs II - Simplicity results

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    We prove simplicity and pure infiniteness results for a certain class of labelled graph CC^*-algebras. We show, by example, that this class of unital labelled graph CC^*-algebras is strictly larger than the class of unital graph CC^*-algebras.Comment: 18 pages, 4 figure

    KINEMATIC AND TEMPORAL CHARACTERISfICS OF SELECTED JUDO HIP THROWS

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    The sport of judo, developed In 1882 in Japan by Jigoro Kano, is a refined version of the ancient martial art of jujitsu. Typically when one envisions martial arts, the mental image includes kicks, punches, and other striking techniques. The sport of judo involves none of these, but does permit the use of throwing techniques, mat work similar to wrestling, strangle holds and joint locks at the elbow. Despite its original role as a martial art, judo as practiced today is essentially the highest form of wrestling practiced anywhere in the world (Reay &Hobbs, 1979)

    Human-dominated land uses favour species affiliated with more extreme climates, especially in the tropics

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    Rapid human population growth has driven conversion of land for uses such as agriculture, transportation and buildings. The removal of natural vegetation changes local climate, with human‐dominated land uses often warmer and drier than natural habitats. Yet, it remains an open question whether land‐use changes influence the composition of ecological assemblages in a direction consistent with the mechanism of local climatic change. Here, we used a global database of terrestrial vertebrates (mammals, birds, reptiles and amphibians) to test whether human‐dominated land uses systematically favour species with distinctive realised climatic niches. We 1) explored the responses of community‐average temperature and precipitation niches to different types of land use, 2) quantified the abundances of species with distinctive climatic niches across land uses and 3) tested for differences in emergent patterns in communities from tropical versus temperate latitudes. We found that, in comparison to species from undisturbed natural habitats, the average animal found in human‐altered habitats lives in areas with higher maximum and lower minimum temperatures and higher maximum and lower minimum precipitation levels. We further found that tropical assemblages diverged more strongly than temperate assemblages between natural and human‐altered habitats, possibly because tropical species are more sensitive to climatic conditions. These results strongly implicate the role of land‐use change in favouring species affiliated with more extreme climatic conditions, thus systematically reshaping the composition of terrestrial biological assemblages. Our findings have the potential to inform species' vulnerability assessments and highlight the importance of preserving local climate refugia

    Probing a non-biaxial behavior of infinitely thin hard platelets

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    We give a criterion to test a non-biaxial behavior of infinitely thin hard platelets of D2hD_{2h} symmetry based upon the components of three order parameter tensors. We investigated the nematic behavior of monodisperse infinitely thin rectangular hard platelet systems by using the criterion. Starting with a square platelet system, and we compared it with rectangular platelet systems of various aspect ratios. For each system, we performed equilibration runs by using isobaric Monte Carlo simulations. Each system did not show a biaxial nematic behavior but a uniaxial nematic one, despite of the shape anisotropy of those platelets. The relationship between effective diameters by simulations and theoretical effective diameters of the above systems was also determined.Comment: Submitted to JPS

    Effects of Altitude on Step Test Performance

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    Please view abstract in the attached PDF file

    Domains in Melts of Comb-Coil Diblock Copolymers: Superstrong Segregation Regime

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    Conditions for the crossover from the strong to the superstrong segregation regime are analyzed for the case of comb-coil diblock copolymers. It is shown that the critical interaction energy between the components required to induce the crossover to the superstrong segregation regime is inversely proportional to mb = 1 + n/m, where n is the degree of polymerization of the side chain and m is the distance between successive grafting points. As a result, the superstrong segregation regime, being rather rare in the case of ordinary block copolymers, has a much better chance to be realized in the case of diblock copolymers with combs grafted to one of the blocks.

    On the spectral properties of L_{+-} in three dimensions

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    This paper is part of the radial asymptotic stability analysis of the ground state soliton for either the cubic nonlinear Schrodinger or Klein-Gordon equations in three dimensions. We demonstrate by a rigorous method that the linearized scalar operators which arise in this setting, traditionally denoted by L_{+-}, satisfy the gap property, at least over the radial functions. This means that the interval (0,1] does not contain any eigenvalues of L_{+-} and that the threshold 1 is neither an eigenvalue nor a resonance. The gap property is required in order to prove scattering to the ground states for solutions starting on the center-stable manifold associated with these states. This paper therefore provides the final installment in the proof of this scattering property for the cubic Klein-Gordon and Schrodinger equations in the radial case, see the recent theory of Nakanishi and the third author, as well as the earlier work of the third author and Beceanu on NLS. The method developed here is quite general, and applicable to other spectral problems which arise in the theory of nonlinear equations
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