811 research outputs found

    The Damping Constant of Tuning Forks

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    The differences in the damping constants of tuning forks while testing hearing by both air and bone conduction are discussed. New methods of obtaining the damping constant are described

    Assessing antioxidant activity of tea extracts and some of chemicals using voltammetry and potentiometry

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    The comparison of antioxidant activity of tea extracts and some chemicals was conducted by independent methods: voltammetry and potentiometry. Except for few cases, we showed satisfactory agreement between test substances activity rows obtained by two different methods. Mechanisms of antioxidative action were proposed. Presumably, sample components are involved in competing reactions like reduction-oxidation and complexation reactions. Limitations and advantages of both methods were defined

    Spin Gap in Two-Dimensional Heisenberg Model for CaV4_4O9_9

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    We investigate the mechanism of spin gap formation in a two-dimensional model relevant to Mott insulators such as CaV4_4O9_9. From the perturbation expansion and quantum Monte Carlo calculations, the origin of the spin gap is ascribed to the four-site plaquette singlet in contrast to the dimer gap established in the generalized dimerized Heisenberg model.Comment: 8 pages, 6 figures available upon request (Revtex

    On the existence of a finite-temperature transition in the two-dimensional gauge glass

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    Results from Monte Carlo simulations of the two-dimensional gauge glass supporting a zero-temperature transition are presented. A finite-size scaling analysis of the correlation length shows that the system does not exhibit spin-glass order at finite temperatures. These results are compared to earlier claims of a finite-temperature transition.Comment: 4 pages, 2 figure

    On the Use of Finite-Size Scaling to Measure Spin-Glass Exponents

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    Finite-size scaling (FSS) is a standard technique for measuring scaling exponents in spin glasses. Here we present a critique of this approach, emphasizing the need for all length scales to be large compared to microscopic scales. In particular we show that the replacement, in FSS analyses, of the correlation length by its asymptotic scaling form can lead to apparently good scaling collapses with the wrong values of the scaling exponents.Comment: RevTeX, 5 page

    Organizational learning and emotion: constructing collective meaning in support of strategic themes

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    Missing in the organizational learning literature is an integrative framework that reflects the emotional as well as the cognitive dynamics involved. Here, we take a step in this direction by focusing in depth over time (five years) on a selected organization which manufactures electronic equipment for the office industry. Drawing on personal construct theory, we define organizational learning as the collective re-construal of meaning in the direction of strategically significant themes. We suggest that emotions arise as members reflect on progress or lack of progress in achieving organizational learning. Our evidence suggests that invalidation – where organizational learning fails to correspond with expectations – gives rise to anxiety and frustration, while validation – where organizational learning is aligned with or exceeds expectations – evokes comfort or excitement. Our work aims to capture the key emotions involved as organizational learning proceeds

    Gauge Theory for Quantum Spin Glasses

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    The gauge theory for random spin systems is extended to quantum spin glasses to derive a number of exact and/or rigorous results. The transverse Ising model and the quantum gauge glass are shown to be gauge invariant. For these models, an identity is proved that the expectation value of the gauge invariant operator in the ferromagnetic limit is equal to the one in the classical equilibrium state on the Nishimori line. As a result, a set of inequalities for the correlation function are proved, which restrict the location of the ordered phase. It is also proved that there is no long-range order in the two-dimensional quantum gauge glass in the ground state. The phase diagram for the quantum XY Mattis model is determined.Comment: 15 pages, 2 figure

    Fluctuation Dissipation Ratio in Three-Dimensional Spin Glasses

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    We present an analysis of the data on aging in the three-dimensional Edwards Anderson spin glass model with nearest neighbor interactions, which is well suited for the comparison with a recently developed dynamical mean field theory. We measure the parameter x(q)x(q) describing the violation of the relation among correlation and response function implied by the fluctuation dissipation theorem.Comment: LaTeX 10 pages + 4 figures (appended as uuencoded compressed tar-file), THP81-9
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