1,058 research outputs found
Universal structure of the edge states of the fractional quantum Hall states
We present an effective theory for the bulk fractional quantum Hall states on
the Jain sequences on closed surfaces and show that it has a universal form
whose structure does not change from fraction to fraction. The structure of
this effective theory follows from the condition of global consistency of the
flux attachment transformation on closed surfaces. We derive the theory of the
edge states on a disk that follows naturally from this globally consistent
theory on a torus. We find that, for a fully polarized two-dimensional electron
gas, the edge states for all the Jain filling fractions have
only one propagating edge field that carries both energy and charge, and two
non-propagating edge fields of topological origin that are responsible for the
statistics of the excitations. Explicit results are derived for the electron
and quasiparticle operators and for their propagators at the edge. We show that
these operators create states with the correct charge and statistics. It is
found that the tunneling density of states for all the Jain states scales with
frequency as .Comment: 10 page
Bulk Versus Edge in the Quantum Hall Effect
The manifestation of the bulk quantum Hall effect on edge is the chiral
anomaly. The chiral anomaly {\it is} the underlying principle of the ``edge
approach'' of quantum Hall effect. In that approach, \sxy should not be taken
as the conductance derived from the space-local current-current correlation
function of the pure one-dimensional edge problem.Comment: 4 pages, RevTex, 1 postscript figur
Interlayer Exchange Interactions, SU(4) Soft Waves and Skyrmions in Bilayer Quantum Hall Ferromagnets
The Coulomb exchange interaction is the driving force for quantum coherence
in quantum Hall systems. We construct a microscopic Landau-site Hamiltonian for
the exchange interaction in bilayer quantum Hall ferromagnets, which is
characterized by the SU(4) isospin structure. By taking a continuous limit, the
Hamiltonian gives rise to the SU(4) nonlinear sigma model in the
von-Neumann-lattice formulation. The ground-state energy is evaluated at
filling factors . It is shown at that there are 3
independent soft waves, where only one soft wave is responsible for the
coherent tunneling of electrons between the two layers. It is also shown at
that there are 3 independent skyrmion states apart from the
translational degree of freedom. They are CP skyrmions enjoying the
spin-charge entanglement confined within the \LLL.Comment: 12 pages, 2 figure
Adiabatic limit and the slow motion of vortices in a Chern-Simons-Schr\"odinger system
We study a nonlinear system of partial differential equations in which a
complex field (the Higgs field) evolves according to a nonlinear Schroedinger
equation, coupled to an electromagnetic field whose time evolution is
determined by a Chern-Simons term in the action. In two space dimensions, the
Chern-Simons dynamics is a Galileo invariant evolution for A, which is an
interesting alternative to the Lorentz invariant Maxwell evolution, and is
finding increasing numbers of applications in two dimensional condensed matter
field theory. The system we study, introduced by Manton, is a special case (for
constant external magnetic field, and a point interaction) of the effective
field theory of Zhang, Hansson and Kivelson arising in studies of the
fractional quantum Hall effect. From the mathematical perspective the system is
a natural gauge invariant generalization of the nonlinear Schroedinger
equation, which is also Galileo invariant and admits a self-dual structure with
a resulting large space of topological solitons (the moduli space of self-dual
Ginzburg-Landau vortices). We prove a theorem describing the adiabatic
approximation of this system by a Hamiltonian system on the moduli space. The
approximation holds for values of the Higgs self-coupling constant close to the
self-dual (Bogomolny) value of 1. The viability of the approximation scheme
depends upon the fact that self-dual vortices form a symplectic submanifold of
the phase space (modulo gauge invariance). The theorem provides a rigorous
description of slow vortex dynamics in the near self-dual limit.Comment: Minor typos corrected, one reference added and DOI give
Applicability and Cost Implications for Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors Based on the ODYSSEY Outcomes Trial: Insights From the Department of Veterans Affairs
In the recently presented ODYSSEY Outcomes: Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab trial, alirocumab use in patients with acute coronary syndrome (ACS) and low-density lipoprotein cholesterol (LDL-C) ≥70 mg/dL (or non–high-density lipoprotein cholesterol ≥100 mg/dL or apolipoprotein B ≥80 mg/dL) resulted in a 15% relative (1.6% absolute) reduction in the risk of major adverse cardiovascular events. We evaluated what proportion of patients in the VA Health Care System would qualify for alirocumab on the basis of ODYSSEY Outcomes criteria, how they are currently treated with LDL-C–lowering medications, and the cost implications if other evidence-based medications were used first before a proprotein convertase subtilisin/kexin type 9 inhibitor was considered
Optical Spectra of SNR Candidates in NGC 300
We present moderate-resolution (<5A) long-slit optical spectra of 51 nebular
objects in the nearby Sculptor Group galaxy NGC 300 obtained with the 2.3 meter
Advanced Technology Telescope at Siding Spring Observatory, Australia. Adopting
the criterion of [SII]/Ha>=0.4 to confirm supernova remnants (SNRs) from
optical spectra, we find that of 28 objects previously proposed as SNRs from
optical observations, 22 meet this criterion with six showing [SII]/Ha of less
than 0.4. Of 27 objects suggested as SNRs from radio data, four are associated
with the 28 previously proposed SNRs. Of these four, three (included in the 22
above) meet the criterion. In all, 22 of the 51 nebular objects meet the
[SII]/Ha criterion as SNRs while the nature of the remaining 29 objects remains
undetermined by these observations.Comment: Accepted for publication in Astrophysics & Space Scienc
Very High-Risk ASCVD and Eligibility for Nonstatin Therapies Based on the 2018 AHA/ACC Cholesterol Guidelines
The 2018 American Heart Association/American College of Cardiology Multisociety Cholesterol Guidelines recommend risk stratification among patients with atherosclerotic cardiovascular disease (ASCVD) to identify “very high-risk ASCVD patients.” These patients have characteristics associated with a higher risk of recurrent ASCVD events; consequently, they derive a higher net absolute benefit from addition of ezetimibe and/or a proprotein convertase subtilisin/kexin type 9 inhibitor (PCSK9i) to statin therapy. From a clinical and payer’s perspective, we assessed the proportion of patients with ASCVD who will qualify as very high-risk based on the guideline criteria, their current lipid management, and how this will change with maximizing statin therapy and stepwise use of ezetimibe before consideration for a PCSK9i, as recommended by the 2018 cholesterol guideline
Menus for Feeding Black Holes
Black holes are the ultimate prisons of the Universe, regions of spacetime
where the enormous gravity prohibits matter or even light to escape to
infinity. Yet, matter falling toward the black holes may shine spectacularly,
generating the strongest source of radiation. These sources provide us with
astrophysical laboratories of extreme physical conditions that cannot be
realized on Earth. This chapter offers a review of the basic menus for feeding
matter onto black holes and discusses their observational implications.Comment: 27 pages. Accepted for publication in Space Science Reviews. Also to
appear in hard cover in the Space Sciences Series of ISSI "The Physics of
Accretion onto Black Holes" (Springer Publisher
Simulation techniques for cosmological simulations
Modern cosmological observations allow us to study in great detail the
evolution and history of the large scale structure hierarchy. The fundamental
problem of accurate constraints on the cosmological parameters, within a given
cosmological model, requires precise modelling of the observed structure. In
this paper we briefly review the current most effective techniques of large
scale structure simulations, emphasising both their advantages and
shortcomings. Starting with basics of the direct N-body simulations appropriate
to modelling cold dark matter evolution, we then discuss the direct-sum
technique GRAPE, particle-mesh (PM) and hybrid methods, combining the PM and
the tree algorithms. Simulations of baryonic matter in the Universe often use
hydrodynamic codes based on both particle methods that discretise mass, and
grid-based methods. We briefly describe Eulerian grid methods, and also some
variants of Lagrangian smoothed particle hydrodynamics (SPH) methods.Comment: 42 pages, 16 figures, accepted for publication in Space Science
Reviews, special issue "Clusters of galaxies: beyond the thermal view",
Editor J.S. Kaastra, Chapter 12; work done by an international team at the
International Space Science Institute (ISSI), Bern, organised by J.S.
Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke
Spontaneous Inter-layer Coherence in Double-Layer Quantum-Hall Systems I: Charged Vortices and Kosterlitz-Thouless Phase Transitions
At strong magnetic fields double-layer two-dimensional-electron-gas systems
can form an unusual broken symmetry state with spontaneous inter-layer phase
coherence. In this paper we explore the rich variety of quantum and
finite-temperature phase transitions associated with this broken symmetry. We
describe the system using a pseudospin language in which the layer
degree-of-freedom is mapped to a fictional spin 1/2 degree-of-freedom. With
this mapping the spontaneous symmetry breaking is equivalent to that of a spin
1/2 easy-plane ferromagnet. In this language spin-textures can carry a charge.
In particular, vortices carry e/2 electrical charge and vortex-antivortex pairs
can be neutral or carry charge e. We derive an effective low-energy action and
use it to discuss the charged and collective neutral excitations of the system.
We have obtained the parameters of the Landau-Ginzburg functional from
first-principles estimates and from finite-size exact diagonalization studies.
We use these results to estimate the dependence of the critical temperature for
the Kosterlitz-Thouless phase transition on layer separation.Comment: 56 pages, 19 figures available upon request at
[email protected]. RevTex 3.0. IUCM94-00
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