22,229 research outputs found

    Counterexample Guided Inductive Optimization Applied to Mobile Robots Path Planning (Extended Version)

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    We describe and evaluate a novel optimization-based off-line path planning algorithm for mobile robots based on the Counterexample-Guided Inductive Optimization (CEGIO) technique. CEGIO iteratively employs counterexamples generated from Boolean Satisfiability (SAT) and Satisfiability Modulo Theories (SMT) solvers, in order to guide the optimization process and to ensure global optimization. This paper marks the first application of CEGIO for planning mobile robot path. In particular, CEGIO has been successfully applied to obtain optimal two-dimensional paths for autonomous mobile robots using off-the-shelf SAT and SMT solvers.Comment: 7 pages, 14rd Latin American Robotics Symposium (LARS'2017

    Higher physical fitness levels are associated with less language decline in healthy ageing

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    Healthy ageing is associated with decline in cognitive abilities such as language. Aerobic fitness has been shown to ameliorate decline in some cognitive domains, but the potential benefits for language have not been examined. In a cross-sectional sample, we investigated the relationship between aerobic fitness and tip-of-the-tongue states. These are among the most frequent cognitive failures in healthy older adults and occur when a speaker knows a word but is unable to produce it. We found that healthy older adults indeed experience more tip-of-the-tongue states than young adults. Importantly, higher aerobic fitness levels decrease the probability of experiencing tip-of-the-tongue states in healthy older adults. Fitness-related differences in word finding abilities are observed over and above effects of age. This is the first demonstration of a link between aerobic fitness and language functioning in healthy older adults

    Dipping Turkey Eggs Prior to Incubation

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    Many commercial turkey hatcheries have been dipping eggs in antibiotic solutions prior to incubation in an attempt to control various respiratory infections in young poults. A study was completed this past year with eggs from a breeder flock of a known history of Mycoplasma gallisepticum infection. Eggs were incubated in separate incubators with and without dipping in a solution of 3,000 ppm tylosin tartrate, 2,500 ppm kanamycin sulfate and 1,000 ppm zephiran chloride. Poults of each group were fed to market age on two dietary energy series, one essentially containing an additional 165 Gal of M.E./kg from animal fat additions, with protein levels and all other components remaining constant

    High-fidelity trapped-ion quantum logic using near-field microwaves

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    We demonstrate a two-qubit logic gate driven by near-field microwaves in a room-temperature microfabricated ion trap. We measure a gate fidelity of 99.7(1)\%, which is above the minimum threshold required for fault-tolerant quantum computing. The gate is applied directly to 43^{43}Ca+^+ "atomic clock" qubits (coherence time T2∗≈50 sT_2^*\approx 50\,\mathrm{s}) using the microwave magnetic field gradient produced by a trap electrode. We introduce a dynamically-decoupled gate method, which stabilizes the qubits against fluctuating a.c.\ Zeeman shifts and avoids the need to null the microwave field

    Stable coupling of nonconforming, high-order finite difference methods

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    The article of record as published may be found at http://dx.doi.org/10.1137/15M1022823A methodology for handling block-to-block coupling of nonconforming, multiblock summation-by-parts finite difference methods is proposed. The coupling is based on the construction of projection operators that move a finite difference grid solution along an interface to a space of piecewise defined functions; we specifically consider discontinuous, piecewise polynomial functions. The constructed projection operators are compatible with the underlying summation-by-parts energy norm. Using the linear wave equation in two dimensions as a model problem, energy stability of the coupled numerical method is proven for the case of curved, nonconforming block-to-block interfaces. To further demonstrate the power of the coupling procedure, we show how it allows for the development of a provably energy stable coupling between curvilinear finite difference methods and a curved-triangle discontinuous Galerkin method. The theoretical results are verified through numerical solutions on curved meshes as well as eigenvalue analysis.Approved for public release; distribution is unlimited
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