30,858 research outputs found

    Towards Large-scale Inconsistency Measurement

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    We investigate the problem of inconsistency measurement on large knowledge bases by considering stream-based inconsistency measurement, i.e., we investigate inconsistency measures that cannot consider a knowledge base as a whole but process it within a stream. For that, we present, first, a novel inconsistency measure that is apt to be applied to the streaming case and, second, stream-based approximations for the new and some existing inconsistency measures. We conduct an extensive empirical analysis on the behavior of these inconsistency measures on large knowledge bases, in terms of runtime, accuracy, and scalability. We conclude that for two of these measures, the approximation of the new inconsistency measure and an approximation of the contension inconsistency measure, large-scale inconsistency measurement is feasible.Comment: International Workshop on Reactive Concepts in Knowledge Representation (ReactKnow 2014), co-located with the 21st European Conference on Artificial Intelligence (ECAI 2014). Proceedings of the International Workshop on Reactive Concepts in Knowledge Representation (ReactKnow 2014), pages 63-70, technical report, ISSN 1430-3701, Leipzig University, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-15056

    Study and Design of a Cesium Bombardment Ion Engine System

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    Cesium bombardment ion engine system design, modification, and testin

    Confocal laser scanning microscopy (CLSM) study of hepatocytes cultured on collagen films and gels

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    Summary of paper describing the process whereby primary hepatocyte cultures form an integral part of many hybrid artificial liver designs, and the extracellular matrix environment of the cultures is an important factor for optimal expression of hepatocyte-specific phenotype. This study investigates the effect of incorporating 20% chondroitin-6-sulphate (Ch6SO4), a glycosaminoglycan (GAG), into collagen films and gels, and crosslinking the films and the gels with 1,6-diaminohexane (DAH) on the viability of hepatocytes cultured for 48 hours

    Optimal eavesdropping on QKD without quantum memory

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    We consider the security of the BB84, six-state and SARG04 quantum key distribution protocols when the eavesdropper doesn't have access to a quantum memory. In this case, Eve's most general strategy is to measure her ancilla with an appropriate POVM designed to take advantage of the post-measurement information that will be released during the sifting phase of the protocol. After an optimization on all the parameters accessible to Eve, our method provides us with new bounds for the security of six-state and SARG04 against a memoryless adversary. In particular, for the six-state protocol we show that the maximum QBER for which a secure key can be extracted is increased from 12.6% (for collective attacks) to 20.4% with the memoryless assumption.Comment: 7 pages, 3 figures. Analysis of six-state and SARG04 QKD protocols adde

    Design and testing of a contra-rotating tidal current turbine

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    A contra-rotating marine current turbine has a number of attractive features: nearzero reactive torque on the support structure, near-zero swirl in the wake, and high relative inter-rotor rotational speeds. Modified blade element modelling theory has been used to design and predict the characteristics of such a turbine, and a model turbine and test rig have been constructed. Tests in a towing tank demonstrated the feasibility of the concept. Power coefficients were high for such a small model and in excellent agreement with predictions, confirming the accuracy of the computational modelling procedures. High-frequency blade loading data were obtained in the course of the experiments. These show the anticipated dynamic components for a contra-rotating machine. Flow visualization of the wake verified the lack of swirl behind the turbine. A larger machine is presently under construction for sea trials

    Collective Spin-Density-Wave Response Perpendicular to the Chains of the Quasi One-Dimensional Conductor (TMTSF)2PF6

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    Microwave experiments along all three directions of the spin-density-wave model compound (TMTSF)2_2PF6_6 reveal that the pinned mode resonance is present along the aa and b′b^{\prime} axes. The collective transport is considered to be the fingerprint of the condensate. In contrast to common quasi one-dimensional models, the density wave also slides in the perpendicular b′b^{\prime} direction. The collective response is absent along the least conducting c∗c^* direction.Comment: 3 pages, 4 figure

    The NASA Astrophysics Data System: Data Holdings

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    Since its inception in 1993, the ADS Abstract Service has become an indispensable research tool for astronomers and astrophysicists worldwide. In those seven years, much effort has been directed toward improving both the quantity and the quality of references in the database. From the original database of approximately 160,000 astronomy abstracts, our dataset has grown almost tenfold to approximately 1.5 million references covering astronomy, astrophysics, planetary sciences, physics, optics, and engineering. We collect and standardize data from approximately 200 journals and present the resulting information in a uniform, coherent manner. With the cooperation of journal publishers worldwide, we have been able to place scans of full journal articles on-line back to the first volumes of many astronomical journals, and we are able to link to current version of articles, abstracts, and datasets for essentially all of the current astronomy literature. The trend toward electronic publishing in the field, the use of electronic submission of abstracts for journal articles and conference proceedings, and the increasingly prominent use of the World Wide Web to disseminate information have enabled the ADS to build a database unparalleled in other disciplines. The ADS can be accessed at http://adswww.harvard.eduComment: 24 pages, 1 figure, 6 tables, 3 appendice

    Time dependent diffusion in a disordered medium with partially absorbing walls: A perturbative approach

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    We present an analytical study of the time dependent diffusion coefficient in a dilute suspension of spheres with partially absorbing boundary condition. Following Kirkpatrick (J. Chem. Phys. 76, 4255) we obtain a perturbative expansion for the time dependent particle density using volume fraction ff of spheres as an expansion parameter. The exact single particle tt-operator for partially absorbing boundary condition is used to obtain a closed form time-dependent diffusion coefficient D(t)D(t) accurate to first order in the volume fraction ff. Short and long time limits of D(t)D(t) are checked against the known short-time results for partially or fully absorbing boundary conditions and long-time results for reflecting boundary conditions. For fully absorbing boundary condition the long time diffusion coefficient is found to be D(t)=5a2/(12fD0t)+O((D0t/a2)−2)D(t)=5 a^2/(12 f D_{0} t) +O((D_0t/a^2)^{-2}), to the first order of perturbation theory. Here ff is small but non-zero, D0D_0 the diffusion coefficient in the absence of spheres, and aa the radius of the spheres. The validity of this perturbative result is discussed
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