3,215 research outputs found

    Spiked Instantons from Intersecting D-branes

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    The moduli space of spiked instantons that arises in the context of the BPS/CFT correspondence is realised as the moduli space of classical vacua, i.e. low-energy open string field configurations, of a certain stack of intersecting D1-branes and D5-branes in Type IIB string theory. The presence of a constant B-field induces an interesting dynamics involving the tachyon condensation.Comment: 50 page

    The Problem of Adhesion Methods and Locomotion Mechanism Development for Wall-Climbing Robots

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    This review considers a problem in the development of mobile robot adhesion methods with vertical surfaces and the appropriate locomotion mechanism design. The evolution of adhesion methods for wall-climbing robots (based on friction, magnetic forces, air pressure, electrostatic adhesion, molecular forces, rheological properties of fluids and their combinations) and their locomotion principles (wheeled, tracked, walking, sliding framed and hybrid) is studied. Wall-climbing robots are classified according to the applications, adhesion methods and locomotion mechanisms. The advantages and disadvantages of various adhesion methods and locomotion mechanisms are analyzed in terms of mobility, noiselessness, autonomy and energy efficiency. Focus is placed on the physical and technical aspects of the adhesion methods and the possibility of combining adhesion and locomotion methods

    On standard norm varieties

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    Let pp be a prime integer and FF a field of characteristic 0. Let XX be the {\em norm variety} of a symbol in the Galois cohomology group Hn+1(F,μpn)H^{n+1}(F,\mu_p^{\otimes n}) (for some n1n\geq1), constructed in the proof of the Bloch-Kato conjecture. The main result of the paper affirms that the function field F(X)F(X) has the following property: for any equidimensional variety YY, the change of field homomorphism \CH(Y)\to\CH(Y_{F(X)}) of Chow groups with coefficients in integers localized at pp is surjective in codimensions <(dimX)/(p1)< (\dim X)/(p-1). One of the main ingredients of the proof is a computation of Chow groups of a (generalized) Rost motive (a variant of the main result not relying on this is given in Appendix). Another important ingredient is {\em AA-triviality} of XX, the property saying that the degree homomorphism on \CH_0(X_L) is injective for any field extension L/FL/F with X(L)X(L)\ne\emptyset. The proof involves the theory of rational correspondences reviewed in Appendix.Comment: 38 pages; final version, to appear in Ann. Sci. \'Ec. Norm. Sup\'er. (4

    Fabrication and characterization of Polymer Light Emitting Diodes (PLEDs) for display application

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    The performance of polymer light emitting diode (PLED) strongly depends on materials, fabrication and the structure of the device. Polymer light-emitting diodes typically consists of emitting layer(s) sandwiched between a cathode and an anode. In our study indium tin oxide (ITO) is used as anode, the polymer blend as emitting layer and metals such as aluminum, silver as cathodes. Investigation in this area is focused to fully understand and develop the method of fabrication of PLEDs using the available resources and to understand the effect of variation of blend ratios of polyfluorene polymers (TFB: 9, 9\u27-dioctylfluorene-co-N-(4-butylphenyl) diphenylamine and F8BT: poly (9, 9\u27dioctylfluorene- co-benzothiadiazole)), different cathodes, addition of buffer layer (calcium acetylacetonate [Ca (acac)z]) on the built devices

    Altered white matter structure in auditory tracts following early monocular enucleation

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    Purpose: Similar to early blindness, monocular enucleation (the removal of one eye) early in life results in crossmodal behavioral and morphological adaptations. Previously it has been shown that partial visual deprivation from early monocular enucleation results in structural white matter changes throughout the visual system (Wong et al., 2018). The current study investigated structural white matter of the auditory system in adults who have undergone early monocular enucleation compared to binocular control participants. Methods: We reconstructed four auditory and audiovisual tracts of interest using probabilistic tractography and compared microstructural properties of these tracts to binocularly intact controls using standard diffusion indices. Results: Although both groups demonstrated asymmetries in indices in intrahemispheric tracts, monocular enucleation participants showed asymmetries opposite to control participants in the auditory and A1-V1 tracts. Monocularenucleation participants also demonstrated significantly lower fractional anisotropy in the audiovisual projections contralateral to the enucleated eye relative to control participants. Conclusions: Partial vision loss from early monocular enucleation results in altered structuralYork University Librarie
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