533,803 research outputs found
The random geometry of equilibrium phases
This is a (long) survey about applications of percolation theory in
equilibrium statistical mechanics. The chapters are as follows:
1. Introduction
2. Equilibrium phases
3. Some models
4. Coupling and stochastic domination
5. Percolation
6. Random-cluster representations
7. Uniqueness and exponential mixing from non-percolation
8. Phase transition and percolation
9. Random interactions
10. Continuum modelsComment: 118 pages. Addresses: [email protected]
http://www.mathematik.uni-muenchen.de/~georgii.html [email protected]
http://www.math.chalmers.se/~olleh [email protected]
Comment on "Attractive Forces between Electrons in 2 + 1 Dimensional QED"
It is shown that a model recently proposed for numerical calculations of
bound states in QED is in fact an improper truncation of the Aharonov-Bohm
potential.Comment: 4 page
Doppler effects on velocity spectra observed by MST radars
Recently, wind data from mesophere-stratosphere-troposphere (MST) radars have been used to study the spectra of gravity waves in the atmosphere (Scheffler and Liu, 1985; VanZandt et al., 1985). Since MST radar measures the line-of-sight Doppler velocities, it senses the components of the wave-associated velocities along its beam directions. These components are related through the polarization relations which depend on the frequency and wave number of the wave. Therfore, the radar-observed velocity spectrum will be different from the original gravity-wave spectrum. Their relationship depends on the frequency and wave number of the wave as well as the propagation geometry. This relation can be used to interpret the observed data. It can also be used to test the assumption of gravity-wave spectrum (Scheffler and Liu, 1985). In deriving this relation, the background atmosphere has been assumed to be motionless. Obviously, the Doppler shift due to the background wind will change the shape of the gravity-wave power spectrum as well as its relation with the radar-observed spectrum. Here, researcher's investigate these changes
Linking radio and gamma ray emission in Ap Librae
Ap Lib is one of the rare Low Synchrotron Peaked blazars detected so far at
TeV energies. This type of source is not properly modelled by standard one-zone
leptonic Synchrotron-self-Compton (SSC) emission scenarios. The aim of this
paper is to study the relevance of additional components which should naturally
occur in a SSC scenario for a better understanding of the emission mechanisms,
especially at very high energies (VHE). Methods. We use simultaneous data from
a multi-wavelength campaign of Planck, Swift-UVOT and Swift-XRT telescopes
carried out in February 2010, as well as quasi-simultaneous data of WISE, Fermi
and H.E.S.S. taken in 2010. The multi-lambda emission of Ap Lib is modelled by
a blob-in-jet SSC scenario including the contribution of the base of the VLBI
extended jet, the radiative blob-jet interaction, the accretion disk and its
associated external photon field. We show that signatures of a strong
parsec-scale jet and of an accretion disk emission are present in the SED. We
can link the observationnal VLBI jet features from MOJAVE to parameters
expected for a VHE emitting blob accelerated near the jet base. The VHE
emission appears to be dominated by the inverse-Compton effect of the blob
relativistic electrons interacting with the jet synchrotron radiation. In such
scenario Ap Lib appears as an intermediate source between BL Lac objects and
Flat Spectrum Radio Quasars. Ap Lib could be a bright representative of a
specific class of blazars, in which the parsec-scale jet luminosity is no more
negligible compared to the blob and contributes to the high energy emission via
inverse Compton processes.Comment: 12 pages, 7 figures, Accepted for publication in A&
Exciton-Polariton Quantum Gates Based on Continuous Variables
We propose a continuous variable analog of quantum controlled-NOT gates based
on a system of exciton-polaritons in semiconductor microcavities. This can be
realized by the engineering of parametric interaction between control and
target polariton modes, which can be varied in time. As an explicit setup we
use a system of dipolaritons, which allows for enhancement of parametric
interaction by auxiliary classical fields and scalable multigate system
realization. The calculated fidelity is shown to exceed 99% for realistic
system parameters.Comment: 6 pages, 3 figures + 6 pages, 2 figures supplemental materia
Tensile and fatigue properties of Inconel 718 at cryogenic temperatures
Tests to determine the tensile and fatigue properties of Inconel 718 at cryogenic temperatures show that the alloy increases in strength at low temperatures, with very little change in toughness. The effect of surface finish and grain size on the fatigue properties was also determined
Nonlinear second order ODE's: Factorizations and particular solutions
We present particular solutions for the following important nonlinear second
order differential equations: modified Emden, generalized Lienard, convective
Fisher, and generalized Burgers-Huxley. For the latter two equations these
solutions are obtained in the travelling frame. All these particular solutions
are the result of extending a simple and efficient factorization method that we
developed in Phys. Rev. E 71 (2005) 046607Comment: 6 pages, v3=published versio
Solutions of the Perturbed KDV Equation for Convecting Fluids by Factorizations
In this paper, we obtain some new explicit travelling wave solutions of the
perturbed KdV equation through recent factorization techniques that can be
performed when the coefficients of the equation fulfill a certain condition.
The solutions are obtained by using a two-step factorization procedure through
which the perturbed KdV equation is reduced to a nonlinear second order
differential equation, and to some Bernoulli and Abel type differential
equations whose solutions are expressed in terms of the exponential and
Weierstrass functionsComment: 4 pages, some changes in the text according to referees' suggestions,
added one reference, accepted at Central Europ. J. Phy
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