1,745 research outputs found
Noise-Driven Mechanism for Pattern Formation
We extend the mechanism for noise-induced phase transitions proposed by
Ibanes et al. [Phys. Rev. Lett. 87, 020601-1 (2001)] to pattern formation
phenomena. In contrast with known mechanisms for pure noise-induced pattern
formation, this mechanism is not driven by a short-time instability amplified
by collective effects. The phenomenon is analyzed by means of a modulated mean
field approximation and numerical simulations
Comprehensive study of phase transitions in relaxational systems with field-dependent coefficients
We present a comprehensive study of phase transitions in single-field systems
that relax to a non-equilibrium global steady state. The mechanism we focus on
is not the so-called Stratonovich drift combined with collective effects, but
is instead similar to the one associated with noise-induced transitions a la
Horsthemke-Lefever in zero-dimensional systems. As a consequence, the noise
interpretation (e.g., Ito vs Stratonvich) merely shifts the phase boundaries.
With the help of a mean-field approximation, we present a broad qualitative
picture of the various phase diagrams that can be found in these systems. To
complement the theoretical analysis we present numerical simulations that
confirm the findings of the mean-field theory
Stochastic Stokes' drift of a flexible dumbbell
We consider the stochastic Stokes drift of a flexible dumbbell. The dumbbell
consists of two isotropic Brownian particles connected by a linear spring with
zero natural length, and is advected by a sinusoidal wave. We find an
asymptotic approximation for the Stokes drift in the limit of a weak wave, and
find good agreement with the results of a Monte Carlo simulation. We show that
it is possible to use this effect to sort particles by their flexibility even
when all the particles have the same diffusivity.Comment: 12 pages, 1 figur
Dissipative collapse of the adiabatic piston
An adiabatic piston, separating two granular gases prepared in the same
macroscopic state, is found to eventually collapse to one of the sides. This
new instability is explained by a simple macroscopic theory which is
furthermore in qualitative agreement with hard disk molecular dynamics.Comment: 7 pages, 5 figure
Critical Behaviour of Non-Equilibrium Phase Transitions to Magnetically Ordered States
We describe non-equilibrium phase transitions in arrays of dynamical systems
with cubic nonlinearity driven by multiplicative Gaussian white noise.
Depending on the sign of the spatial coupling we observe transitions to
ferromagnetic or antiferromagnetic ordered states. We discuss the phase
diagram, the order of the transitions, and the critical behaviour. For global
coupling we show analytically that the critical exponent of the magnetization
exhibits a transition from the value 1/2 to a non-universal behaviour depending
on the ratio of noise strength to the magnitude of the spatial coupling.Comment: 4 pages, 5 figure
Alternative derivation of Mie theory with electromagnetic potentials for diffuse particles
Mie's theory of light scattering on spherical particles is being increasingly used in nanophotonics, and these demanding applications have laid bare some shortcomings of Mie theory in its standard formulation. One problem that deserves special attention is the electron spill-out in small metallic nanoparticles, which invalidates the assumption of an abrupt interface. Here we present an alternative derivation of Mie theory without this assumption. To avoid the usual electromagnetic boundary conditions suitable for a hard-wall interface, we set up equations for the electromagnetic potentials instead of the electric and magnetic field. We show that in the limit of a hard-wall interface, the results of the standard Mie theory are recovered. Additionally, a numerical solution scheme is proposed for the equations for the vector potential and the scalar potential. Analysis of the optical cross sections of soft-interface nanospheres shows that the absorption increases and occurs at lower frequencies as compared to hard-walled nanospheres. This effect is rather dramatic in large spheres with large spill-out, due to the disappearance of high-frequency resonance peaks
Testing the no-hair theorem with black hole ringdowns using TIGER
The Einstein Telescope (ET), a proposed third-generation gravitational wave
observatory, would enable tests of the no-hair theorem by looking at the
characteristic frequencies and damping times of black hole ringdown signals. In
previous work it was shown that with a single black hole
at distance Gpc (or redshift ), deviations of a few
percent in the frequencies and damping times of dominant and sub-dominant modes
would be within the range of detectability. Given that such sources may be
relatively rare, it is of interest to see how well the no-hair theorem can be
tested with events at much larger distances and with smaller signal-to-noise
ratios, thus accessing a far bigger volume of space and a larger number of
sources. We employ a model selection scheme called TIGER (Test Infrastructure
for GEneral Relativity), which was originally developed to test general
relativity with weak binary coalescence signals that will be seen in
second-generation detectors such as Advanced LIGO and Advanced Virgo. TIGER is
well-suited for the regime of low signal-to-noise ratio, and information from a
population of sources can be combined so as to arrive at a stronger test. By
performing a range of simulations using the expected noise power spectral
density of Einstein Telescope, we show that with TIGER, similar deviations from
the no-hair theorem as considered in previous work will be detectable with
great confidence using sources distributed uniformly in
co-moving volume out to 50 Gpc ().Comment: 11 pages, 20 figures. Matches version in PR
Intrinsic noise-induced phase transitions: beyond the noise interpretation
We discuss intrinsic noise effects in stochastic multiplicative-noise partial
differential equations, which are qualitatively independent of the noise
interpretation (Ito vs. Stratonovich), in particular in the context of
noise-induced ordering phase transitions. We study a model which, contrary to
all cases known so far, exhibits such ordering transitions when the noise is
interpreted not only according to Stratonovich, but also to Ito. The main
feature of this model is the absence of a linear instability at the transition
point. The dynamical properties of the resulting noise-induced growth processes
are studied and compared in the two interpretations and with a reference
Ginzburg-Landau type model. A detailed discussion of new numerical algorithms
used in both interpretations is also presented.Comment: 9 pages, 8 figures, to be published in Phys. Rev.
Noise induced transition from an absorbing phase to a regime of stochastic spatiotemporal intermittency
We introduce a stochastic partial differential equation capable of
reproducing the main features of spatiotemporal intermittency (STI).
Additionally the model displays a noise induced transition from laminarity to
the STI regime. We show by numerical simulations and a mean-field analysis that
for high noise intensities the system globally evolves to a uniform absorbing
phase, while for noise intensities below a critical value spatiotemporal
intermittence dominates. A quantitative computation of the loci of this
transition in the relevant parameter space is presented.Comment: 4 pages, 6 eps figures. Submitted to Phys. Rev. Lett. See for
additional information http://imedea.uib.es
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