31,822 research outputs found
Recurrence spectrum in smooth dynamical systems
We prove that for conformal expanding maps the return time does have constant
multifractal spectrum. This is the counterpart of the result by Feng and Wu in
the symbolic setting
The Flow of a Viscous Compressible Fluid Through a Very Narrow Gap
The effect of compressibility on the pressure distribution
in the narrow gap between a rotating cylinder and a plane in a viscous fluid was studied by Taylor and Saffman [1] during an investigation of the centripetal pump effect discovered by Reiner [2]
The fate of the Wilson-Fisher fixed point in non-commutative \phi^4
In this article we study non-commutative vector sigma model with the most
general \phi^4 interaction on Moyal-Weyl spaces. We compute the 2- and 4-point
functions to all orders in the large N limit and then apply the approximate
Wilson renormalization group recursion formula to study the renormalized
coupling constants of the theory. The non-commutative Wilson-Fisher fixed point
interpolates between the commutative Wilson-Fisher fixed point of the Ising
universality class which is found to lie at zero value of the critical coupling
constant a_* of the zero dimensional reduction of the theory, and a novel
strongly interacting fixed point which lies at infinite value of a_*
corresponding to maximal non-commutativity beyond which the two-sheeted
structure of a_* as a function of the dilation parameter disappears.Comment: 19 pages, 7 figures, v2:one reference adde
Phase transition and correlation decay in Coupled Map Lattices
For a Coupled Map Lattice with a specific strong coupling emulating
Stavskaya's probabilistic cellular automata, we prove the existence of a phase
transition using a Peierls argument, and exponential convergence to the
invariant measures for a wide class of initial states using a technique of
decoupling originally developed for weak coupling. This implies the exponential
decay, in space and in time, of the correlation functions of the invariant
measures
Irrelevant Interactions without Composite Operators - A Remark on the Universality of Second Order Phase Transitions
We study the critical behaviour of symmetric theory including
irrelevant terms of the form in the bare action,
where is the UV cutoff (corresponding e.g. to the inverse lattice
spacing for a spin system). The main technical tool is renormalization theory
based on the flow equations of the renormalization group which permits to
establish the required convergence statements in generality and rigour. As a
consequence the effect of irrelevant terms on the critical behaviour may be
studied to any order without using renormalization theory for composite
operators. This is a technical simplification and seems preferable from the
physical point of view. In this short note we restrict for simplicity to the
symmetry class of the Ising model, i.e. one component theory. The
method is general, however.Comment: 13 page
Running coupling expansion for the renormalized -trajectory from renormalization invariance
We formulate a renormalized running coupling expansion for the
--function and the potential of the renormalized --trajectory on
four dimensional Euclidean space-time. Renormalization invariance is used as a
first principle. No reference is made to bare quantities. The expansion is
proved to be finite to all orders of perturbation theory. The proof includes a
large momentum bound on the connected free propagator amputated vertices.Comment: 14 pages LaTeX2e, typos and references correcte
On Urabe's criteria of isochronicity
We give a short proof of Urabe's criteria for the isochronicity of periodical
solutions of the equation . We show that apart from the
harmonic oscillator there exists a large family of isochronous potentials which
must all be non-polynomial and not symmetric (an even function of the
coordinate x).Comment: 8 page
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Blue-light filtering spectacle lenses for visual performance, sleep, and macular health in adults
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To assess whether blue-light filtering spectacle lenses impart effects on visual function, provide protection to the macula, or both. We will also examine potential effects on the sleep-wake cycle
Compact Source of EPR Entanglement and Squeezing at Very Low Noise Frequencies
We report on the experimental demonstration of strong quadrature EPR
entanglement and squeezing at very low noise sideband frequencies produced by a
single type-II, self-phase-locked, frequency degenerate optical parametric
oscillator below threshold. The generated two-mode squeezed vacuum state is
preserved for noise frequencies as low as 50 kHz. Designing simple setups able
to generate non-classical states of light in the kHz regime is a key challenge
for high sensitivity detection of ultra-weak physical effects such as
gravitational wave or small beam displacement
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