2,599 research outputs found

    Learning alters theta-nested gamma oscillations in inferotemporal cortex

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    How coupled brain rhythms influence cortical information processing to support learning is unresolved. Local field potential and neuronal activity recordings from 64- electrode arrays in sheep inferotemporal cortex showed that visual discrimination learning increased the amplitude of theta oscillations during stimulus presentation. Coupling between theta and gamma oscillations, the theta/gamma ratio and the regularity of theta phase were also increased, but not neuronal firing rates. A neural network model with fast and slow inhibitory interneurons was developed which generated theta nested gamma. By increasing N-methyl-D-aspartate receptor sensitivity similar learning-evoked changes could be produced. The model revealed that altered theta nested gamma could potentiate downstream neuron responses by temporal desynchronization of excitatory neuron output independent of changes in overall firing frequency. This learning-associated desynchronization was also exhibited by inferotemporal cortex neurons. Changes in theta nested gamma may therefore facilitate learning-associated potentiation by temporal modulation of neuronal firing

    Efficacy and Methodology of Urban Pigeon Control with DRC-1339

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    During 1990 and 1991, feral pigeon (Columbia livia) baiting programs using compound DRC-1339 were conducted in 6 cities in Kentucky and Tennessee. U. S. Department of Agriculture, Animal and Plant Health Inspection Service, Animal Damage Control (ADC) personnel evaluated each problem site, selected bait sites, supervised prebaiting, mixed, and applied toxic bait In most cases, local personnel conducted the prebaiting and disposed of dead birds. Seven pigeon flocks containing 95-735 birds were reduced by up to 100% with 1 or 2 baitings with 0.37% DRC-1339-treated bait Most birds died at their roosting areas or on rooftops where they were not visible to the public. Use of the bait sites by non target birds was minimal, and no non target kills were found during carcass pickup. DRC-1339 appears to be a very effective, selective, and safe means of urban pigeon population reduction

    α\alpha-Scale Decoupling of the Mechanical Relaxation and Diverging Shear Wave Propagation Lengthscale in Triphenylphosphite

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    We have performed depolarized Impulsive Stimulated Scattering experiments to observe shear acoustic phonons in supercooled triphenylphosphite (TPP) from ∼\sim10 - 500 MHz. These measurements, in tandem with previously performed longitudinal and shear measurements, permit further analyses of the relaxation dynamics of TPP within the framework of the mode coupling theory (MCT). Our results provide evidence of α\alpha coupling between the shear and longitudinal degrees of freedom up to a decoupling temperature TcT_c = 231 K. A lower bound length scale of shear wave propagation in liquids verified the exponent predicted by theory in the vicinity of the decoupling temperature

    The Influence of a Goalkeeper as an Outfield Player on Defensive Subsystems in Futsal

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    The aim of this study was to investigate the influence of the goalkeeper as an outfield player on defensive subsystems in the team sport of futsal. For this purpose, all sequences of play involving the goalkeeper (n = 65), and the sequences without a goalkeeper (controls) (n = 11), were selected from digital video footage of a futsal competition, and analysed using TACTO software. The defensive area, attacker-defender distance, and interception distance were used to examine players’ coordination tendencies as a team in completion of successful and unsuccessful passes and shots. Results showed that each team reduced its defensive area as well as its variability in situations where the goalkeeper acted as an outfield player. This finding implies that it was an effective defensive strategy because it led to emergence of more unsuccessful passes. It was also observed that the goalkeeper acting as an outfield player was an effective strategy for attacking in terms of increasing shots at goal

    Thermolectric Materials Based on Intercalated Layered Metallic Systems

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    A novel thermoelectric material in the form of a unit cell including a first reagent intercalated as a semiconducting layer into a metallic layered host and a method for producing the thermoelectric material are disclosed. The unit cell is characterized by a Seebeck coefficient S of 80-140 μV/K° and an electrical conductivity σ of 103 -104 (Ωcm)-1, as well as a figure of merit Z of about 2×10-3 K-1 at 100° K

    Electric field induced biaxiality and the electro-optic effect in a bent-core nematic liquid crystal

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    We report the observation of a biaxial nematic phase in a bent-core molecular system using polarizing microscopy, electro-optics, and dielectric spectroscopy, where we find that the biaxiality exists on a microscopic scale. An application of electric field induces a macroscopic biaxiality and in consequence gives rise to electro-optic switching. This electro-optic effect shows significant potential in applications for displays due to its fast high-contrast response. The observed electro-optic switching is explained in terms of the interaction of the ferroelectric clusters with the electric field

    The Anderson Transition in Two-Dimensional Systems with Spin-Orbit Coupling

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    We report a numerical investigation of the Anderson transition in two-dimensional systems with spin-orbit coupling. An accurate estimate of the critical exponent ν\nu for the divergence of the localization length in this universality class has to our knowledge not been reported in the literature. Here we analyse the SU(2) model. We find that for this model corrections to scaling due to irrelevant scaling variables may be neglected permitting an accurate estimate of the exponent ν=2.73±0.02\nu=2.73 \pm 0.02

    Metallic Nanoscale Fibers from Stable Iodine-Doped Carbon Nanotubes

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    A method of doping involves soaking single-walled carbon nanotubes in molten iodine. Excess physisorbed iodine may then be removed by annealing
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