6,497 research outputs found

    Measurement of the thorium-228 activity in solutions cavitated by ultrasonic sound

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    We show that cavitation of a solution of thorium-228 in water does not induce its transformation at a faster rate than the natural radioactive decay. We measured the activity of a thorium-228 solution in water before, and after, it was subjected to a cavitation at 44 kHz and 250250 W for 90 minutes in order to observe any change in the thorium half-life. The results were compared to the original activity of the sample and we observed no change. Our results and conclusions conflict with those in a recent paper by F. Cardone et. al. [Phys. Lett. A 373 (2009) 1956-1958].Comment: 6 pages, 1 figure, 2 tables, v1 submitted to Physics Letters A. v2: minor corrections, change caption for tables (include comment for counter efficiency with uncertainty) and symbols for beta-alph

    A retrospective on J.D. Sargan and his contribution to Econometrics

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    This retrospective provides a biographical history of Denis Sargan's career and reviews his contributions to econometrics, emphasizing the breadth of his work in both theoretical and applied econometrics. We include a complete bibliography for Denis and a list of PhD theses that he supervised - students were a substantive facet of his profesional life. Finally, two of Denis' previously unpublished manuscripts on model building now appear in print. Keywords; dynamic specification, econometrics, error correction model, finite sample distributions, identification, instrumental variables, model building, numerical computation, prices, production function, specification searches, wages

    Gust penetration loads and elastic vehicle response for Saturn 5 launch vehicles

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    Analysis of gust penetration loads and associated elastic vehicle response of Saturn 5 launch vehicles AS-505 through AS-508 penetrating sinusoidal gust

    Multi-Layer Cyber-Physical Security and Resilience for Smart Grid

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    The smart grid is a large-scale complex system that integrates communication technologies with the physical layer operation of the energy systems. Security and resilience mechanisms by design are important to provide guarantee operations for the system. This chapter provides a layered perspective of the smart grid security and discusses game and decision theory as a tool to model the interactions among system components and the interaction between attackers and the system. We discuss game-theoretic applications and challenges in the design of cross-layer robust and resilient controller, secure network routing protocol at the data communication and networking layers, and the challenges of the information security at the management layer of the grid. The chapter will discuss the future directions of using game-theoretic tools in addressing multi-layer security issues in the smart grid.Comment: 16 page

    Relation between geometric phases of entangled bi-partite systems and their subsystems

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    This paper focuses on the geometric phase of entangled states of bi-partite systems under bi-local unitary evolution. We investigate the relation between the geometric phase of the system and those of the subsystems. It is shown that (1) the geometric phase of cyclic entangled states with non-degenerate eigenvalues can always be decomposed into a sum of weighted non-modular pure state phases pertaining to the separable components of the Schmidt decomposition, though the same cannot be said in the non-cyclic case, and (2) the geometric phase of the mixed state of one subsystem is generally different from that of the entangled state even by keeping the other subsystem fixed, but the two phases are the same when the evolution operator satisfies conditions where each component in the Schmidt decomposition is parallel transported

    Distributions of Error Correction Tests for Cointegration

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    This paper provides cumulative distribution functions, densities, and finite sample critical values for the single-equation error correction statistic for testing cointegration. Graphs and response surfaces summarize extensive Monte Carlo simulations and highlight simple dependencies of the statistic's quantiles on the number of variables in the error correction model, the choice of deterministic components, and the estimation sample size. The response surfaces provide a convenient way for calculating finite sample critical values at standard levels; and a computer program, freely available over the Internet, can be used to calculate both critical values and p-values. Three empirical examples illustrate these tools.

    Correlation induced non-Abelian quantum holonomies

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    In the context of two-particle interferometry, we construct a parallel transport condition that is based on the maximization of coincidence intensity with respect to local unitary operations on one of the subsystems. The dependence on correlation is investigated and it is found that the holonomy group is generally non-Abelian, but Abelian for uncorrelated systems. It is found that our framework contains the L\'{e}vay geometric phase [2004 {\it J. Phys. A: Math. Gen.} {\bf 37} 1821] in the case of two-qubit systems undergoing local SU(2) evolutions.Comment: Minor corrections; journal reference adde
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