175 research outputs found
Bursts of ciguatera and endo-upwelling process on coral reef
Il est proposé une relation de cause à affet entre les flambées de ciguatera consécutives à une agression subie par une zone récifale et les sorties d'eaux interstitielles par endo upwelling riches en nutriments. Ceux-ci n'étant plus utilisés par un écosystÚme algo corallien stressé ou éliminé, le sont par des planctontes épibenthiques comme #Gambierdiscus toxicus$ dont la population augmente brutalement. (Résumé d'auteur
Vortex Rings in Fast Rotating Bose-Einstein Condensates
When Bose-Eintein condensates are rotated sufficiently fast, a giant vortex
phase appears, that is the condensate becomes annular with no vortices in the
bulk but a macroscopic phase circulation around the central hole. In a former
paper [M. Correggi, N. Rougerie, J. Yngvason, {\it arXiv:1005.0686}] we have
studied this phenomenon by minimizing the two dimensional Gross-Pitaevskii
energy on the unit disc. In particular we computed an upper bound to the
critical speed for the transition to the giant vortex phase. In this paper we
confirm that this upper bound is optimal by proving that if the rotation speed
is taken slightly below the threshold there are vortices in the condensate. We
prove that they gather along a particular circle on which they are evenly
distributed. This is done by providing new upper and lower bounds to the GP
energy.Comment: to appear in Archive of Rational Mechanics and Analysi
Lowest Landau Level vortex structure of a Bose-Einstein condensate rotating in a harmonic plus quartic trap
We investigate the vortex patterns appearing in a two-dimensional annular
Bose-Einstein condensate rotating in a quadratic plus quartic confining
potential. We show that in the limit of small anharmonicity the
Gross-Pitaevskii energy can be minimized amongst the Lowest Landau Level wave
functions and use this particular form to get theoretical results in the spirit
of [A. Aftalion X. Blanc F. Nier, Phys. Rev. A 73, 011601(R) (2006)]. In
particular, we show that the vortex pattern is infinite but not uniform. We
also compute numerically the complete vortex structure: it is an Abrikosov
lattice strongly distorted near the edges of the condensate with multiply
quantized vortices appearing at the center of the trap.Comment: 8 pages, 4 figure
Australian Sphingidae â DNA Barcodes Challenge Current Species Boundaries and Distributions
© 2014 Rougerie et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article
A global checklist of the Bombycoidea (Insecta: Lepidoptera)
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published pdf plus supplementary data file.NHM Repositor
The Transition to a Giant Vortex Phase in a Fast Rotating Bose-Einstein Condensate
We study the Gross-Pitaevskii (GP) energy functional for a fast rotating
Bose-Einstein condensate on the unit disc in two dimensions. Writing the
coupling parameter as 1 / \eps^2 we consider the asymptotic regime \eps
\to 0 with the angular velocity proportional to
(\eps^2|\log\eps|)^{-1} . We prove that if \Omega = \Omega_0
(\eps^2|\log\eps|)^{-1} and then a minimizer of
the GP energy functional has no zeros in an annulus at the boundary of the disc
that contains the bulk of the mass. The vorticity resides in a complementary
`hole' around the center where the density is vanishingly small. Moreover, we
prove a lower bound to the ground state energy that matches, up to small
errors, the upper bound obtained from an optimal giant vortex trial function,
and also that the winding number of a GP minimizer around the disc is in accord
with the phase of this trial function.Comment: 52 pages, PDFLaTex. Minor corrections, sign convention modified. To
be published in Commun. Math. Phy
Vortex density models for superconductivity and superfluidity
We study some functionals that describe the density of vortex lines in
superconductors subject to an applied magnetic field, and in Bose-Einstein
condensates subject to rotational forcing, in quite general domains in 3
dimensions. These functionals are derived from more basic models via
Gamma-convergence, here and in a companion paper. In our main results, we use
these functionals to obtain descriptions of the critical applied magnetic field
(for superconductors) and forcing (for Bose-Einstein), above which ground
states exhibit nontrivial vorticity, as well as a characterization of the
vortex density in terms of a non local vector-valued generalization of the
classical obstacle problem.Comment: 34 page
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