338 research outputs found
Phase instabilities in hexagonal patterns
The general form of the amplitude equations for a hexagonal pattern including
spatial terms is discussed. At the lowest order we obtain the phase equation
for such patterns. The general expression of the diffusion coefficients is
given and the contributions of the new spatial terms are analysed in this
paper. From these coefficients the phase stability regions in a hexagonal
pattern are determined. In the case of Benard-Marangoni instability our results
agree qualitatively with numerical simulations performed recently.Comment: 6 pages, 6 figures, to appear in Europhys. Let
Chaotic synchronization of coupled electron-wave systems with backward waves
The chaotic synchronization of two electron-wave media with interacting
backward waves and cubic phase nonlinearity is investigated in the paper. To
detect the chaotic synchronization regime we use a new approach, the so-called
time scale synchronization [Chaos, 14 (3) 603-610 (2004)]. This approach is
based on the consideration of the infinite set of chaotic signals' phases
introduced by means of continuous wavelet transform. The complex space-time
dynamics of the active media and mechanisms of the time scale synchronization
appearance are considered.Comment: 11 pages, 7 figures, published in CHAOS, 15 (2005) 01370
Dissipative dynamics of an open Bose Einstein condensate
As an atomic Bose Einstein condensate BEC.is coupled to a source of uncondensed atoms at the same temperature and
to a sink extraction towards an atom laser.the idealized description in terms of a Gross–Pitaevsky equation GP. no longer
holds. Under suitable physical assumptions we show that the dissipative BEC obeys a Complex Ginzburg Landau equation
CGL.and for some parameter range it undergoes a space time patterning. As a consequence, the density of BEC atoms
within the trap displays non trivial space time correlations, which can be detected by monitoring the density profile of the
outgoing atom laser. The patterning condition requires a negative scattering length, as e.g. in 7Li. In such a case we expect a
many domain collapsed regime, rather than a single one as reported for a closed BEC. q2000 Elsevier Science B.V. All
rights reserved
Planform selection in two-layer Benard-Marangoni convection
Benard-Marangoni convection in a system of two superimposed liquids is
investigated theoretically. Extending previous studies the complete
hydrodynamics of both layers is treated and buoyancy is consistently taken into
account. The planform selection problem between rolls, squares and hexagons is
investigated by explicitly calculating the coefficients of an appropriate
amplitude equation from the parameters of the fluids. The results are compared
with recent experiments on two-layer systems in which squares at onset have
been reported.Comment: 17 pages, 7 figures, oscillatory instability included, typos
corrected, references adde
Avaliação pós-colheita de cultivares de pêras produzidas no Submédio São Francisco.
O objetivo do presente trabalho é avaliar a qualidade pós-colheita de quatro cultivares de peras produzidas sob irrigação no Semiárido Brasileiro
Transfer of Communication Skills to the Workplace during Clinical Rounds : Impact of a Program for Residents
peer reviewe
Asymmetric coupling effects in the synchronization of spatially extended chaotic systems
We analyze the effects of asymmetric couplings in setting different synchronization states for a pair
of unidimensional fields obeying complex Ginzburg-Landau equations. Novel features such as asymmetry
enhanced complete synchronization, limits for the appearance of phase synchronized states, and
selection of the final synchronized dynamics are reported and characterized
Towards a quantitative phase-field model of two-phase solidification
We construct a diffuse-interface model of two-phase solidification that
quantitatively reproduces the classic free boundary problem on solid-liquid
interfaces in the thin-interface limit. Convergence tests and comparisons with
boundary integral simulations of eutectic growth show good accuracy for
steady-state lamellae, but the results for limit cycles depend on the interface
thickness through the trijunction behavior. This raises the fundamental issue
of diffuse multiple-junction dynamics.Comment: 4 pages, 2 figures. Better final discussion. 1 reference adde
Synchonization between two Hele-Shaw cells
Abstract. Complete synchronization between two Hele-Shaw cells is exam-
ined. The two dynamical systems are chaotic in time and spatially extended
in two dimensions. It is shown that a large number of connectors are needed
to achieve synchronization. In particular, we have studied how the number of
connectors influences the dynamical regime that is set inside the Hele-Shaw
cells
Is it possible to improve the breaking bad news skills of residents when a relative is present? A randomised study.
peer reviewe
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