625 research outputs found
Dissipationless BCS Dynamics with Large Branch Imbalance
In many situations a BCS-type superconductor will develop an imbalance
between the populations of the holelike and electronlike spectral branches.
This imbalance suppresses the gap. It has been noted by Gal'perin et al. [Sov.
Phys. JETP 54, 1126 (1981)] that at large imbalance, when the gap is
substantially suppressed, an instability develops. The analytic treatment of
the system beyond the instability point is complicated by the fact that the
Boltzmann approach breaks down. We study the short-time behavior following the
instability, in the collisionless regime, using methods developed by Yuzbashyan
et al. [J. Phys. A 38, 7831 (2005); Phys. Rev. B 72, 220503(R) (2005)].Comment: 12 pages, 3 figure
Quantum Hall transitions: An exact theory based on conformal restriction
We revisit the problem of the plateau transition in the integer quantum Hall
effect. Here we develop an analytical approach for this transition, based on
the theory of conformal restriction. This is a mathematical theory that was
recently developed within the context of the Schramm-Loewner evolution which
describes the stochastic geometry of fractal curves and other stochastic
geometrical fractal objects in 2D space. Observables elucidating the connection
with the plateau transition include the so-called point-contact conductances
(PCCs) between points on the boundary of the sample, described within the
language of the Chalker-Coddington network model. We show that the
disorder-averaged PCCs are characterized by classical probabilities for certain
geometric objects in the plane (pictures), occurring with positive statistical
weights, that satisfy the crucial restriction property with respect to changes
in the shape of the sample with absorbing boundaries. Upon combining this
restriction property with the expected conformal invariance at the transition
point, we employ the mathematical theory of conformal restriction measures to
relate the disorder-averaged PCCs to correlation functions of primary operators
in a conformal field theory (of central charge ). We show how this can be
used to calculate these functions in a number of geometries with various
boundary conditions. Since our results employ only the conformal restriction
property, they are equally applicable to a number of other critical disordered
electronic systems in 2D. For most of these systems, we also predict exact
values of critical exponents related to the spatial behavior of various
disorder-averaged PCCs.Comment: Published versio
On harmonic measure of critical curves
Fractal geometry of critical curves appearing in 2D critical systems is
characterized by their harmonic measure. For systems described by conformal
field theories with central charge , scaling exponents of
harmonic measure have been computed by B. Duplantier [Phys. Rev. Lett. {\bf
84}, 1363 (2000)] by relating the problem to boundary two-dimensional gravity.
We present a simple argument that allows us to connect harmonic measure of
critical curves to operators obtained by fusion of primary fields, and compute
characteristics of fractal geometry by means of regular methods of conformal
field theory. The method is not limited to theories with .Comment: Some more correction
Critical curves in conformally invariant statistical systems
We consider critical curves -- conformally invariant curves that appear at
critical points of two-dimensional statistical mechanical systems. We show how
to describe these curves in terms of the Coulomb gas formalism of conformal
field theory (CFT). We also provide links between this description and the
stochastic (Schramm-) Loewner evolution (SLE). The connection appears in the
long-time limit of stochastic evolution of various SLE observables related to
CFT primary fields. We show how the multifractal spectrum of harmonic measure
and other fractal characteristics of critical curves can be obtained.Comment: Published versio
Generic critical points of normal matrix ensembles
The evolution of the degenerate complex curve associated with the ensemble at
a generic critical point is related to the finite time singularities of
Laplacian Growth. It is shown that the scaling behavior at a critical point of
singular geometry is described by the first Painlev\'e
transcendent. The regularization of the curve resulting from discretization is
discussed.Comment: Based on a talk given at the conference on Random Matrices, Random
Processes and Integrable Systems, CRM Montreal, June 200
Distribution of Class 1 Integrons with IS26-Mediated Deletions in Their 3′-Conserved Segments in Escherichia coli of Human and Animal Origin
Class 1 integrons play a role in the emergence of multi-resistant bacteria by facilitating the recruitment of gene cassettes encoding antibiotic resistance genes. 512 E. coli strains sourced from humans (n = 202), animals (n = 304) and the environment (n = 6) were screened for the presence of the intI1 gene. In 31/79 integron positive E. coli strains, the gene cassette regions could not be PCR amplified using standard primers. DNA sequence analysis of 6 serologically diverse strains revealed atypical integrons harboured the dfrA5 cassette gene and only 24 bp of the integron 3′-conserved segment (CS) remained, due to the insertion of IS26. PCR targeting intI1 and IS26 followed by restriction fragment length polymorphism (RFLP) analysis identified the integron-dfrA5-IS26 element in 27 E. coli strains of bovine origin and 4 strains of human origin. Southern hybridization and transformation studies revealed the integron-dfrA5-IS26 gene arrangement was either chromosomally located or plasmid borne. Plasmid location in 4/9 E. coli strains and PCR linkage of Tn21 transposition genes with the intI1 gene in 20/31 strains, suggests this element is readily disseminated by horizontal transfer
Adaptation of Autocatalytic Fluctuations to Diffusive Noise
Evolution of a system of diffusing and proliferating mortal reactants is
analyzed in the presence of randomly moving catalysts. While the continuum
description of the problem predicts reactant extinction as the average growth
rate becomes negative, growth rate fluctuations induced by the discrete nature
of the agents are shown to allow for an active phase, where reactants
proliferate as their spatial configuration adapts to the fluctuations of the
catalysts density. The model is explored by employing field theoretical
techniques, numerical simulations and strong coupling analysis. For d<=2, the
system is shown to exhibits an active phase at any growth rate, while for d>2 a
kinetic phase transition is predicted. The applicability of this model as a
prototype for a host of phenomena which exhibit self organization is discussed.Comment: 6 pages 6 figur
Molecular Characterization of a 21.4 Kilobase Antibiotic Resistance Plasmid from an α-Hemolytic Escherichia coli O108:H- Human Clinical Isolate
This study characterizes the 21.4 kilobase plasmid pECTm80 isolated from Escherichia coli strain 80, an α hemolytic human clinical diarrhoeal isolate (serotype O108:H-). DNA sequence analysis of pECTm80 revealed it belonged to incompatibility group X1, and contained plasmid partition and toxin-antitoxin systems, an R6K-like triple origin (ori) replication system, genes required for replication regulation, insertion sequences IS1R, ISEc37 and a truncated transposase gene (Tn3-like ΔtnpA) of the Tn3 family, and carried a class 2 integron. The class 2 integron of pECTm80 contains an intact cassette array dfrA1-sat2, encoding resistance to trimethoprim and streptothricin, and an aadA1 gene cassette truncated by the insertion of IS1R. The complex plasmid replication system includes α, β and γ origins of replication. Pairwise BLASTn comparison of pECTm80 with plasmid pE001 reveals a conserved plasmid backbone suggestive of a common ancestral lineage. Plasmid pECTm80 is of potential clinical importance, as it carries multiple genes to ensure its stable maintenance through successive bacterial cell divisions and multiple antibiotic resistance genes
Review Essay : Industrial Organization and Socialist Development in China
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68697/2/10.1177_009770047900500204.pd
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