589 research outputs found
Travelling waves in a drifting flux lattice
Starting from the time-dependent Ginzburg-Landau (TDGL) equations for a type
II superconductor, we derive the equations of motion for the displacement field
of a moving vortex lattice without inertia or pinning. We show that it is
linearly stable and, surprisingly, that it supports wavelike long-wavelength
excitations arising not from inertia or elasticity but from the
strain-dependent mobility of the moving lattice. It should be possible to image
these waves, whose speeds are a few \mu m/s, using fast scanning tunnelling
microscopy.Comment: 4 pages, revtex, 2 .eps figures imbedded in paper, title shortened,
minor textual change
Investigation of short range structural order in Zr69.5Cu12Ni11Al7.5 and Zr41.5Ti41.5Ni17 glasses, using X ray absorption spectroscopy and ab initio molecular dynamics simulations
Short-range order has been investigated in Zr69.5Cu12Ni11Al7.5and Zr41.5Ti41.5Ni17metallic glasses using X-ray absorption spectroscopy andab initiomolecular dynamics simulations. While both of these alloys are good glass formers, there is a difference in their glass-forming abilities (Zr41.5Ti41.5Ni17> Zr69.5Cu12Ni11Al7.5). This difference is explained by inciting the relative importance of strong chemical order, icosahedral content, cluster symmetry and configuration diversity.</jats:p
One-Dimensional Approximation of Viscous Flows
Attention has been paid to the similarity and duality between the
Gregory-Laflamme instability of black strings and the Rayleigh-Plateau
instability of extended fluids. In this paper, we derive a set of simple
(1+1)-dimensional equations from the Navier-Stokes equations describing thin
flows of (non-relativistic and incompressible) viscous fluids. This
formulation, a generalization of the theory of drop formation by Eggers and his
collaborators, would make it possible to examine the final fate of
Rayleigh-Plateau instability, its dimensional dependence, and possible
self-similar behaviors before and after the drop formation, in the context of
fluid/gravity correspondence.Comment: 17 pages, 3 figures; v2: refs & comments adde
The Future of Neutrino Mass Measurements: Terrestrial, Astrophysical, and Cosmological Measurements in the Next Decade. Highlights of the NuMass 2013 Workshop. Milano, Italy, February 4 - 7, 2013
The third Workshop of the NuMass series ("The Future of Neutrino Mass
Measurements: Terrestrial, Astrophysical, and Cosmological Measurements in the
Next Decade: NuMass 2013") was held at Dipartimento di Fisica "G. Occhialini,
University of Milano-Bicocca in Milano, Italy, on 4-7 February 2013. The goal
of this international workshop was to review the status and future of direct
and indirect neutrino mass measurements in the laboratory as well as from
astrophysical and cosmological observations. This paper collects most of the
contributions presented during the Workshop
Recurrent De Novo NAHR Reciprocal Duplications in the ATAD3 Gene Cluster Cause a Neurogenetic Trait with Perturbed Cholesterol and Mitochondrial Metabolism.
Recent studies have identified both recessive and dominant forms of mitochondrial disease that result from ATAD3A variants. The recessive form includes subjects with biallelic deletions mediated by non-allelic homologous recombination. We report five unrelated neonates with a lethal metabolic disorder characterized by cardiomyopathy, corneal opacities, encephalopathy, hypotonia, and seizures in whom a monoallelic reciprocal duplication at the ATAD3 locus was identified. Analysis of the breakpoint junction fragment indicated that these 67 kb heterozygous duplications were likely mediated by non-allelic homologous recombination at regions of high sequence identity in ATAD3A exon 11 and ATAD3C exon 7. At the recombinant junction, the duplication allele produces a fusion gene derived from ATAD3A and ATAD3C, the protein product of which lacks key functional residues. Analysis of fibroblasts derived from two affected individuals shows that the fusion gene product is expressed and stable. These cells display perturbed cholesterol and mitochondrial DNA organization similar to that observed for individuals with severe ATAD3A deficiency. We hypothesize that the fusion protein acts through a dominant-negative mechanism to cause this fatal mitochondrial disorder. Our data delineate a molecular diagnosis for this disorder, extend the clinical spectrum associated with structural variation at the ATAD3 locus, and identify a third mutational mechanism for ATAD3 gene cluster variants. These results further affirm structural variant mutagenesis mechanisms in sporadic disease traits, emphasize the importance of copy number analysis in molecular genomic diagnosis, and highlight some of the challenges of detecting and interpreting clinically relevant rare gene rearrangements from next-generation sequencing data
Jamming transition in a homogeneous one-dimensional system: the Bus Route Model
We present a driven diffusive model which we call the Bus Route Model. The
model is defined on a one-dimensional lattice, with each lattice site having
two binary variables, one of which is conserved (``buses'') and one of which is
non-conserved (``passengers''). The buses are driven in a preferred direction
and are slowed down by the presence of passengers who arrive with rate lambda.
We study the model by simulation, heuristic argument and a mean-field theory.
All these approaches provide strong evidence of a transition between an
inhomogeneous ``jammed'' phase (where the buses bunch together) and a
homogeneous phase as the bus density is increased. However, we argue that a
strict phase transition is present only in the limit lambda -> 0. For small
lambda, we argue that the transition is replaced by an abrupt crossover which
is exponentially sharp in 1/lambda. We also study the coarsening of gaps
between buses in the jammed regime. An alternative interpretation of the model
is given in which the spaces between ``buses'' and the buses themselves are
interchanged. This describes a system of particles whose mobility decreases the
longer they have been stationary and could provide a model for, say, the flow
of a gelling or sticky material along a pipe.Comment: 17 pages Revtex, 20 figures, submitted to Phys. Rev.
Polyethersulfone supported titanium complexes as ethylene polymerization catalysts
Polyethersulfone has been used as the support to anchor TiCl4 or Cp2TiCl2 through dative 'O-Ti' bond. The supported complexes in combination with methylaluminoxane are effective ethylene polymerization catalysts. The polyethylene made by the supported catalysts, especially the titanocene-derived catalyst, has low polydispersity indicating single site character
Phase Separation and Coarsening in One-Dimensional Driven Diffusive Systems: Local Dynaimcs Leading to Long-Range Hamiltonians
A driven system of three species of particle diffusing on a ring is studied
in detail. The dynamics is local and conserves the three densities. A simple
argument suggesting that the model should phase separate and break the
translational symmetry is given. We show that for the special case where the
three densities are equal the model obeys detailed balance and the steady-state
distribution is governed by a Hamiltonian with asymmetric long-range
interactions. This provides an explicit demonstration of a simple mechanism for
breaking of ergodicity in one dimension. The steady state of finite-size
systems is studied using a generalized matrix product ansatz. The coarsening
process leading to phase separation is studied numerically and in a mean-field
model. The system exhibits slow dynamics due to trapping in metastable states
whose number is exponentially large in the system size. The typical domain size
is shown to grow logarithmically in time. Generalizations to a larger number of
species are discussed.Comment: Revtex, 29 Pages, 7 figures, uses epsf.sty, submitted to Phys. Rev.
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