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1.
《Nuclear Physics B》2001,600(1):197-202
We make the supergravity solutions describing the branes (D3 branes and D4 branes) localized within the D6 branes in the near core region of D6 brane. From the D=11 solutions (M3 branes and M4 branes with the ZN identifications in the transverse space) we obtain the D=10 supergravity solutions of D3 branes localized within D6 branes and D4 branes localized within D6 branes by reducing the dimension down to D=10 along a circular direction of S3 part of the transverse space. M3 brane solution leads to D=10 background representing D3 branes localized on D6 branes in the region close to the D6 branes core. M4 branes lead to the D4 branes localized on D6 branes in the region close to the D6 brane core.  相似文献   

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We consider a formulation of nonperturbative two-dimensional quantum gravity coupled to a single bosonic field (d=1 matter). Starting from a matrix realization of the discretized model, we express the continuum theory as a double scaling limit in which the 2D cosmological constant g tends towards a critical value gc, and the string coupling 1/N→0, with the scaling parameter ∝1n (g-gc)/(g-gc)N held fixed. We find that in this formulation logarithmic corrections already present at tree level persist to all higher genus, suggesting a behavior different from the previously considered cases of d<1 matter.  相似文献   

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Kavokin  A. V.  Goupalov  S. V. 《Il Nuovo Cimento D》1995,17(11):1527-1530
Il Nuovo Cimento D - Interaction of two magnetic polarons formed either by single carriers or by excitons is considered in bulk crystal, quantum well and quantum wire. It is shown that the magnetic...  相似文献   

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Measured and simulated minimum quench energies (MQE) for short samples are doubtful when estimating disturbance tolerance of an impregnated superconducting magnet. If measurements are performed at liquid cryogen, the cooling provided by the cryogen causes MQE to be high. At a conduction-cooled system, the transverse heat conduction is neglected causing low MQE. Even though these conditions can be artificially brought closer to the ones in an impregnated magnet, it is difficult to estimate by short-sample measurement the MQE of a superconducting coil. These similar difficulties are present at simulations. On the other hand, 1D and 2D measurements and simulations can be used, e.g., to compare wires or consider effect of insulation layer thickness, but according to the results only in a rough quantitative way. In this paper, we compare MQE and normal zone propagation velocity simulations of an MgB2 wire with 1D, 2D and 3D finite element method models to focus on the different results given by the models employing different dimensions.  相似文献   

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We use the formalism of Generalised Geometry to characterise in general the supersymmetric backgrounds in type II supergravity that have a null Killing vector. We then specify this analysis to configurations that preserve the same supersymmetries as the D1–D5–P system compactified on a four-manifold. We give a set of equations on the forms defining the supergravity background that are equivalent to the supersymmetry constraints and the equations of motion. This study is motivated by the search of new microstate geometries for the D1–D5–P black hole. As an example, we rewrite the linearised three-charge solution of arXiv:hep-th/0311092 in our formalism and show how to extend it to a non-linear, regular and asymptotically flat configuration.  相似文献   

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In memory of professor D. D. Ivanenko  相似文献   

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In this paper, we consider a cache-enable device-to-device (D2D) communication network with user mobility and design a mobility-aware coded caching scheme to exploit multicasting opportunities for reducing network traffic. In addition to the static cache memory that can be used to reap coded caching gains, we assign a dynamic cache memory to mobile users such that users who never meet can still exchange contents via relaying. We consider content exchange as an information flow among dynamic cache memories of mobile users and leverage network coding to reduce network traffic. Specifically, we transfer our storage and broadcast problem into a network coding problem. By solving the formulated network coding problem, we obtain a dynamic content replacement and broadcast strategy. Numerical results verify that our algorithm significantly outperforms the random and greedy algorithms in terms of the amount of broadcasting data, and the standard Ford–Fulkerson algorithm in terms of the successful decoding ratio.  相似文献   

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In this note we study the Landau–Hall problem in the 2D and 3D unit sphere, that is, the motion of a charged particle in the presence of a static magnetic field. The magnetic flow is completely determined for any Riemannian surface of constant Gauss curvature, in particular, the unit 2D sphere. For the 3D case we consider Killing magnetic fields on the unit sphere, and we show that the magnetic flowlines are helices with the given Killing vector field as its axis.  相似文献   

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We consider a thick brane model using two interacting scalar fields in 7D and 8D gravity. Using a special choice of potential energy, we obtain numerically regular asymptotically flat vacuum solutions. The possibility of obtaining the similar solutions for an arbitrary number of extra spatial dimensions is being estimated.  相似文献   

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The ratio of the fluorescence intensities from the two lines of the yellow sodium doublet has been investigated in several hydrogen-based and acetylene-based flames and with various types of lasers as excitation sources. The systematic deviation from 2 for the ratio D2/D1 when either D1 or D2 are used as exciting transitions can be simply explained by the relative difference in the values of the collisional mixing constants between the excited P-levels and the collisional quenching constants transferring atoms from both P-levels to the ground S-level. Results obtained in flames characterized by different values of the quantum efficiency follow the behavior predicted by the fluorescence expressions obtained by a simple, steady-state theoretical approach.  相似文献   

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<正>One-dimensional (1D) and two-dimensional (2D) materials,such as nanowires,graphene,and transition metal dichalcogenides (TMDs),have received emerging research study in the past ten years [1-3].They have demonstrated to be idea building blocks for fabricating high-performance photodetector devices owing to their unique electrical and optical properties[4-6].However,the photoresponsivity,detectivity,and  相似文献   

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A novel procedure for reconstruction of 2D separated-local-field (SLF) NMR spectra from projections of 1D NMR data is presented. The technique, dubbed SLF projection reconstruction from one-dimensional spectra (SLF-PRODI), is particularly useful for uniaxially oriented membrane protein samples and represents a fast and robust alternative to the popular PISEMA experiment which correlates (1)H-(15)N dipole-dipole couplings with (15)N chemical shifts. The different 1D projections in the SLF-PRODI experiment are obtained from 1D spectra recorded under influence of homonuclear decoupling sequences with different scaling factors for the heteronuclear dipolar couplings. We demonstrate experimentally and numerically that as few as 2-4 1D projections will normally be sufficient to reconstruct a 2D SLF-PRODI spectrum with a quality resembling typical PISEMA spectra, leading to significant reduction of the acquisition time.  相似文献   

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It is emphasized that two‐dimensional photonic crystals (2D PC) have not only a great potential for the development of 2D nanophotonics in the inplane waveguided configuration, but that they may also open the way to other brilliant developments, with an extension to out‐of‐plane operation, along a 2.5D nanophotonics approach. In this 2.5D approach, a 1D–2D high index contrast lateral structuration is combined with a 1D high index contrast vertical structuration, using multilayer membrane stacks including 1D–2D photonic crystal membranes, thus resulting in so‐called 2.5D PC. As a specific illustration of recent achievements along this approach, new families of VCSEL structures are presented.  相似文献   

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The 3D structure of randomly polarized light fields is exemplified by its polarization singularities: lines along which the polarization is purely circular (C lines) and surfaces on which the polarization is linear (L surfaces). We visualize these polarization singularities experimentally in vector laser speckle fields, and in numerical simulations of random wave superpositions. Our results confirm previous analytical predictions [M. R. Dennis, Opt. Commun. 213, 201 (2002)] regarding the statistical distribution of types of C points and relate their 2D properties to their 3D structure.  相似文献   

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