Meissner response of superconductors with inhomogeneous penetration depths

We discuss the Meissner response to a known field source of superconductors having inhomogeneities in their penetration depth. We simplify the general problem by assuming that the perturbations of the fields by the penetration depth inhomogeneities are small. We present expressions for inhomogeneities in several geometries, but concentrate for comparison with experiment on planar defects, perpendicular to the sample surfaces, with superfluid densities different from the rest of the samples. These calculations are relevant for magnetic microscopies, such as Scanning Superconducting Quantum Interference Device (SQUID) and Magnetic Force Microscope, which image the local diamagnetic susceptibility of a sample.Comment: 9 pages, 4 figure

Determining the vortex tilt relative to a superconductor surface

It is of interest to determine the exit angle of a vortex from a superconducting surface, since this affects the intervortex interactions and their consequences. Two ways to determine this angle are to image the vortex magnetic fields above the surface, or the vortex core shape at the surface. In this work we evaluate the field h(x, y, z) above a flat superconducting surface x, y and the currents J(x,y) at that surface for a straight vortex tilted relative to the normal to the surface, for both the isotropic and anisotropic cases. In principle, these results can be used to determine the vortex exit tilt angle from analyses of magnetic field imaging or density of states data.Comment: 5 pages, 4 figure

Electron-Acoustic Phonon Energy Loss Rate in Multi-Component Electron Systems with Symmetric and Asymmetric Coupling Constants

We consider electron-phonon (\textit{e-ph}) energy loss rate in 3D and 2D multi-component electron systems in semiconductors. We allow general asymmetry in the \textit{e-ph} coupling constants (matrix elements), i.e., we allow that the coupling depends on the electron sub-system index. We derive a multi-component \textit{e-ph}power loss formula, which takes into account the asymmetric coupling and links the total \textit{e-ph} energy loss rate to the density response matrix of the total electron system. We write the density response matrix within mean field approximation, which leads to coexistence of\ symmetric energy loss rate $F_{S}(T)$ and asymmetric energy loss rate $F_{A}(T)$ with total energy loss rate $F(T)=F_{S}(T)+F_{A}(T)$ at temperature $T$. The symmetric component F_{S}(T) $is equivalent to the conventional single-sub-system energy loss rate in the literature, and in the Bloch-Gr\"{u}neisen limit we reproduce a set of well-known power laws$F_{S}(T)\propto T^{n_{S}}$, where the prefactor and power$n_{S}$depend on electron system dimensionality and electron mean free path. For$F_{A}(T)$we produce a new set of power laws F_{A}(T)\propto T^{n_{A}}$. Screening strongly reduces the symmetric coupling, but the asymmetric coupling is unscreened, provided that the inter-sub-system Coulomb interactions are strong. The lack of screening enhances $F_{A}(T)$ and the total energy loss rate $F(T)$. Especially, in the strong screening limit we find $F_{A}(T)\gg F_{S}(T)$. A canonical example of strongly asymmetric \textit{e-ph} matrix elements is the deformation potential coupling in many-valley semiconductors.Comment: v2: Typos corrected. Some notations changed. Section III.C is embedded in Section III.B. Paper accepted to PR

Inventories in developing countries : levels and determinants - a red flag for competitiveness and growth

Raw materials inventories in the manufacturing sector in the 1970s, 1980s, and 1990s were two to five times as high in developing countries as in the United States, despite the fact that in most developing countries real interest rates are at least twice as high. Given the high cost of capital in most developing countries, these high inventory levels have an enormous impact on the cost of doing business and on productivity and competitiveness. Poor infrastructure and ineffective regulation as well as deficiencies in market development - rather than the interest rates and uncertainty - are the main determinants of these differences. Cross-country estimates show that a one-standard-deviation improvement in infrastructure reduces raw materials inventories by 27-47 percent. Poorly functioning markets, as measured by the ratio of transfers and subsidies to GDP, are also an important factor, with a one-standard-deviation improvement leading to a 19-30 percent reduction in raw materials inventories. The authors show that these reductions in raw materials inventories are not offset by a reduction in finished goods inventories upstream. The policy implications are clear and strong. Improvements in infrastructure (roads, ports, and telecommunications) can help to significantly reduce inventory levels (and thus the cost of doing business), especially when accompanied by effective regulation and the development and deregulation of associated markets.Economic Theory&Research,Banks&Banking Reform,Environmental Economics&Policies,Transport and Trade Logistics,Common Carriers Industry

Just-in-case inventories - a cross-country analysis

The authors find that raw materials inventories in the manufacturing sector in the 1970s and 1980s were two to three times higher in developing countries than in the United States, despite the fact that in most developing countries real interest rates were at least twice as high. Those significantly high levels of inventories are a burden and an obstacle to country competitiveness and need to be addressed. Poor infrastructure and ineffective regulation, as well as deficiencies in market development, rather than the traditional factors used in inventory models (such as interest rates and uncertainty), are the main determinants and explain these differences. Cross-country estimations show that a one standard deviation worsening of infrastructure increases raw materials inventories by 11 percent to 37 percent, and a one standard deviation worsening of markets increases raw materials inventories by 18 percent to 37 percent. These findings are robust across a number of different proxies and specifications, including an industry-level specification that controls for fixed country effects.Banks&Banking Reform,Environmental Economics&Policies,Markets and Market Access,Economic Theory&Research,Labor Policies,Economic Theory&Research,Banks&Banking Reform,Environmental Economics&Policies,Access to Markets,Markets and Market Access

Statistics of fluctuations for two types of crossover: from ballistic to diffusive regime and from orthogonal to unitary ensemble

In our previous publication [Kogan et al, Phys. Rev. {\bf 48}, 9404 (1993)] we considered the issue of statistics of radiation diffusively propagating in a disordered medium. The consideration was in the framework of diagrammatic techniques and a new representation for the intensity distribution function in terms of connected diagrams only was proposed. Here we use similar approach to treat the issue of statistics in the regime of the crossover between ballistic and diffusive transport. We find that even small contribution from coherent component decreases by one half the intensity distribution function for small values of intensity and also produces oscillations of the distribution function. We also apply this method to study statistics of fluctuations of wave functions of chaotic electrons in a quantum dot in an arbitrary magnetic field, by calculating the single state local density in the regime of the crossover between the orthogonal and unitary ensemble.Comment: Revtex, 3 pages + 2 ps.figures in uuencoded file, a version which clarifies and unites the results of two previous submission

Induced Dilaton in Topologically Massive Quantum Field Theory

We consider the conformally-invariant coupling of topologically massive gravity to a dynamical massless scalar field theory on a three-manifold with boundary. We show that, in the phase of spontaneously broken Lorentz and Weyl symmetries, this theory induces the target space zero mode of the vertex operator for the string dilaton field on the boundary of the three-dimensional manifold. By a further coupling to topologically massive gauge fields in the bulk, we demonstrate directly from the three-dimensional theory that this dilaton field transforms in the expected way under duality transformations so as to preserve the mass gaps in the spectra of the gauge and gravitational sectors of the quantum field theory. We show that this implies an intimate dynamical relationship between T-duality and S-duality transformations of the quantum string theory. The dilaton in this model couples bulk and worldsheet degrees of freedom to each other and generates a dynamical string coupling.Comment: 26 pages RevTeX, 1 figure, uses epsf.st

Liouville Dressed Weights and Renormalization of Spin in Topologically Massive Gravity

We examine the relations between observables in two- and three-dimensional quantum gravity by studying the coupling of topologically massive gravity to matter fields in non-trivial representations of the three-dimensional Lorentz group. We show that the gravitational renormalization of spin up to one-loop order in these theories reproduces the leading orders of the KPZ scaling relations for quantum Liouville theory. We demonstrate that the two-dimensional scaling dimensions can be computed from tree-level Aharonov-Bohm scattering amplitudes between the charged particles in the limit where the three-dimensional theory possesses local conformal invariance. We show how the three-dimensional description defines scale-dependent weights by computing the one-loop order anomalous magnetic moment of fermions in a background electromagnetic field due to the renormalization by topologically massive gravity. We also discuss some aspects concerning the different phases of three-dimensional quantum gravity and argue that the topological ones may be related to the branched polymer phase of two-dimensional quantum gravity.Comment: 37 pages LaTeX; uses macro package FEYNMAN.te

Logarithmic Operators and Dynamical Extention of The Symmetry Group in the Bosonic SU(2)_0 and SUSY SU(2)_2 WZNW Models

We study the operator product expansion in the bosonic $SU(2)_0$ and SUSY $SU(2)_2$ WZNW models. We find that these OPEs contain both logarithmic operators and new conserved currents, leading to an extension of the symmetry group.Comment: 16 pages, Late