4,335 research outputs found

    Spinors for Spinning p-Branes

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    The group of the p-brane world volume preserving diffeomorphism is considered. The infinite-dimensional spinors of this group are related, by the nonlinear realization techniques, to the corresponding spinors of its linear subgroup, that are constructed explicitly. An algebraic construction of the Virasoro and Neveu-Schwarz-Ramond algebras, based on this infinite-dimensional spinors and tensors, is demonstrated.Comment: 18 page

    Using the dynamic mapping of the microwave brain radiation for functional studies

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    In this study, organizational principles of the radiophysical complex are proposed for simultaneous measurements of the brightness temperature fluctuations of the human brain and parameters of the autonomic nervous system. A new structure of the medical microwave radiothermograph is suggested based on the parametric compensation of losses in the circuit elements of the thermobalance. The aim of this article is to justify the structural organization of the radiophysical complex for the recording and joint real-time analysis of processes of the microwave radiation formation in the brain tissue and characteristics of the autonomic nervous system. Description of the radiophysical complex MRTHR with realization of these principles is presented. The peculiarity of the proposed radiophysical complex is in passive elements that do not contain electronic nodes and blocks and are inside the shielded cabin. In order to increase the accuracy of the brightness temperature of the deep brain structures measurement in the radiophysical complex a new structure is implemented. This structure of the medical microwave radiothermograph is based on the parametric compensation of losses in the circuit elements of the thermobalance

    Multi-filament structures in relativistic self-focusing

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    A simple model is derived to prove the multi-filament structure of relativistic self-focusing with ultra-intense lasers. Exact analytical solutions describing the transverse structure of waveguide channels with electron cavitation, for which both the relativistic and ponderomotive nonlinearities are taken into account, are presented.Comment: 21 pages, 12 figures, submitted to Physical Review

    On the full, strongly exceptional collections on toric varieties with Picard number three

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    We investigate full strongly exceptional collections on smooth, com- plete toric varieties. We obtain explicit results for a large family of varieties with Picard number three, containing many of the families already known. We also describe the relations between the collections and the split of the push forward of the trivial line bundle by the toric Frobenius morphism

    Use of accelerated helium-3 ions for determining oxygen and carbon impurities in some pure materials

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    Methods are developed for the determination of O impurity in Be and Si carbide and concurrent determination of C and O impurities in Si and W by irradiation with accelerated He-3 ions and subsequent activity measurements of C-11 and F-18 formed from C and O with the aid of a gamma-gamma coincidence spectrometer. Techniques for determining O in Ge and Ga arsenide with radiochemical separation of F-18 are also described

    Could One Find Petroleum Using Neutrino Oscillations in Matter?

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    In neutrino physics, it is now widely believed that neutrino oscillations are influenced by the presence of matter, modifying the energy spectrum produced by a neutrino beam traversing the Earth. Here, we will discuss the reverse problem, i.e. what could be learned about the Earth's interior from a single neutrino baseline energy spectrum, especially about the Earth's mantle. We will use a statistical analysis with a low-energy neutrino beam under very optimistic assumptions. At the end, we will note that it is hard to find petroleum with such a method, though it is not too far away from technical feasibility.Comment: 6 pages, 4 figures, EPL LaTeX. Final version to be published in Europhys. Let

    Vortex Polarity Switching in Magnets with Surface Anisotropy

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    Vortex core reversal in magnetic particle is essentially influenced by a surface anisotropy. Under the action of a perpendicular static magnetic field the vortex core undergoes a shape deformationof pillow- or barrel-shaped type, depending on the type of the surface anisotropy. This deformation plays a key point in the switching mechanism: We predict that the vortex polarity switching is accompanied (i) by a linear singularity in case of Heisenberg magnet with bulk anisotropy only and (ii) by a point singularities in case of surface anisotropy or exchange anisotropy. We study in details the switching process using spin-lattice simulations and propose a simple analytical description using a wired core model, which provides an adequate description of the Bloch point statics, its dynamics and the Bloch point mediated switching process. Our analytical predictions are confirmed by spin-lattice simulations for Heisenberg magnet and micromagnetic simulations for nanomagnet with account of a dipolar interaction.Comment: 17 pages, 15 figure
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