Vortex Phases of Rotating Superfluids

We report on the first mathematically rigorous proofs of a transition to a giant vortex state of a superfluid in rotating anharmonic traps. The analysis is carried out within two-dimensional Gross-Pitaevskii theory at large coupling constant and large rotational velocity and is based on precise asymptotic estimates on the ground state energy. An interesting aspect is a significant difference between 'soft' anharmonic traps (like a quartic plus quadratic trapping potential) and traps with a fixed boundary. In the former case vortices persist in the bulk until the width of the annulus becomes comparable to the size of the vortex cores. In the second case the transition already takes place in a parameter regime where the size of vortices is very small relative to the width of the annulus. Moreover, the density profiles in the annulus are different in the two cases. In both cases rotational symmetry of the density in a true ground state is broken, even though a symmetric variational ansatz gives an excellent approximation to the energy.Comment: For the Proceedings of 21st International Laser Physics Workshop, Calgary, July 23-27, 201

How do general practitioners put preventive care recommendations into practice? A cross-sectional study in Switzerland and France.

We previously identified that general practitioners (GPs) in French-speaking regions of Europe had a variable uptake of common preventive recommendations. In this study, we describe GPs' reports of how they put different preventive recommendations into practice. Cross-sectional study conducted in 2015 in Switzerland and France. 3400 randomly selected GPs were asked to complete a postal (n=1100) or online (n=2300) questionnaire. GPs who exclusively practiced complementary and alternative medicine were not eligible for the study. 764 GPs (response rate: postal 47%, online 11%) returned the questionnaire (428 in Switzerland and 336 in France). We investigated how the GPs performed five preventive practices (screening for dyslipidaemia, colorectal and prostate cancer, identification of hazardous alcohol consumption and brief intervention), examining which age group they selected, the screening frequency, the test they used, whether they favoured shared decision for prostate cancer screening and their definition of hazardous alcohol use. A large variability was observed in the way in which GPs provide these practices. 41% reported screening yearly for cholesterol, starting and stopping at variable ages. 82% did not use any test to identify hazardous drinking. The most common responses for defining hazardous drinking were, for men, ≥21 drinks/week (24%) and ≥4 drinks/occasion for binge drinking (20%), and for women, ≥14 drinks/week (28%) and ≥3 drinks/occasion (21%). Screening for colorectal cancer, mainly with colonoscopy in Switzerland (86%) and stool-based tests in France (93%), was provided every 10 years in Switzerland (65%) and 2 years in France (91%) to patients between 50 years (87%) and 75 years (67%). Prostate cancer screening, usually with shared decision (82%), was provided yearly (62%) to patients between 50 years (74%) and 75-80 years (32%-34%). The large diversity in the way these practices are provided needs to be addressed, as it could be related to some misunderstandingof the current guidelines, to barriers for guideline uptake or, more likely, to the absence of agreement between the various recommendations

Critical Rotational Speeds for Superfluids in Homogeneous Traps

We present an asymptotic analysis of the effects of rapid rotation on the ground state properties of a superfluid confined in a two-dimensional trap. The trapping potential is assumed to be radial and homogeneous of degree larger than two in addition to a quadratic term. Three critical rotational velocities are identified, marking respectively the first appearance of vortices, the creation of a `hole' of low density within a vortex lattice, and the emergence of a giant vortex state free of vortices in the bulk. These phenomena have previously been established rigorously for a `flat' trap with fixed boundary but the `soft' traps considered in the present paper exhibit some significant differences, in particular the giant vortex regime, that necessitate a new approach. These differences concern both the shape of the bulk profile and the size of vortices relative to the width of the annulus where the bulk of the superfluid resides. Close to the giant vortex transition the profile is of Thomas-Fermi type in `flat' traps, whereas it is gaussian for soft traps, and the `last' vortices to survive in the bulk before the giant vortex transition are small relative to the width of the annulus in the former case but of comparable size in the latter.Comment: To appear in J. Math. Phys, published versio

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 $\Omega$ proportional to (\eps^2|\log\eps|)^{-1} . We prove that if \Omega = \Omega_0 (\eps^2|\log\eps|)^{-1} and $\Omega_0 > 2(3\pi)^{-1}$ 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

Derivation of renormalized Gibbs measures from equilibrium many-body quantum Bose gases

We review our recent result on the rigorous derivation of the renormalized Gibbs measure from the many-body Gibbs state in 1D and 2D. The many-body renormalization is accomplished by simply tuning the chemical potential in the grand-canonical ensemble, which is analogous to the Wick ordering in the classical field theory.Comment: Contribution to Proceedings of the International Congress of Mathematical Physics, Montreal, Canada, July 23-28, 201

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

Genes Suggest Ancestral Colour Polymorphisms Are Shared across Morphologically Cryptic Species in Arctic Bumblebees

email Suzanne orcd idCopyright: © 2015 Williams 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

Fam65b is a new transcriptional target of FOXO1 that regulates RhoA signaling for T lymphocyte migration

Forkhead box Os (FOXOs) transcription factors favor both T cell quiescence and trafficking through their control of the expression of genes involved in cell cycle progression, adhesion and homing. Here, we report that the product of the fam65b gene is a new transcriptional target of FOXO1 that regulates RhoA activity. We show that Fam65b binds the small GTPase RhoA via a non canonical domain and represses its activity by decreasing its GTP loading. As a consequence, Fam65b negatively regulates chemokine-induced responses such as adhesion, morphological polarisation and migration. Therefore, these results show the existence of a new functional link between FOXO1 and RhoA pathways, through which the FOXO1 target Fam65b tonically dampens chemokine-induced migration by repressing RhoA activity

Depleted dissolved organic carbon and distinct bacterial communities in the water column of a rapid-flushing coral reef ecosystem

Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in The ISME Journal 5 (2011): 1374–1387, doi:10.1038/ismej.2011.12.Coral reefs are highly productive ecosystems bathed in unproductive, low-nutrient oceanic waters, where microbially-dominated food webs are supported largely by bacterioplankton recycling of dissolved compounds. Despite evidence that benthic reef organisms efficiently scavenge particulate organic matter and inorganic nutrients from advected oceanic waters, our understanding of the role of bacterioplankton and dissolved organic matter in the interaction between reefs and the surrounding ocean remains limited. Here we present the results of a four-year study conducted in a well-characterized coral reef ecosystem (Paopao Bay, Moorea, French Polynesia) where changes in bacterioplankton abundance and dissolved organic carbon (DOC) concentrations were quantified and bacterial community structure variation was examined along spatial gradients of the reef:ocean interface. Our results illustrate that the reef is consistently depleted in concentrations of both DOC and bacterioplankton relative to offshore waters (averaging 79 µmol L-1 DOC and 5.5 X 108 cells L-1 offshore and 68 µmol L-1 DOC and 3.1 X 108 cells L-1 over the reef, respectively) across a four year time period. In addition, using a suite of culture-independent measures of bacterial community structure, we found consistent differentiation of reef bacterioplankton communities from those offshore or in a nearby embayment across all taxonomic levels. Reef habitats were enriched in Gamma-, Delta-, and Beta-proteobacteria, Bacteriodetes, Actinobacteria and Firmicutes. Specific bacterial phylotypes, including members of the SAR11, SAR116, Flavobacteria, and Synechococcus clades, exhibited clear gradients in relative abundance among nearshore habitats. Our observations indicate that this reef system removes oceanic DOC and exerts selective pressures on bacterioplankton community structure on timescales approximating reef water residence times, observations which are notable both because fringing reefs do not exhibit long residence times (unlike those characteristic of atoll lagoons) and because oceanic DOC is generally recalcitrant to degradation by ambient microbial assemblages. Our findings thus have interesting implications for the role of oceanic DOM and bacterioplankton in the ecology and metabolism of reef ecosystems.This project was supported by the US National Science Foundation Moorea Coral Reef Long Term Ecological Research project (NSF OCE-0417412) through minigrants to CAC and NSF OCE-0927411 to CAC as well as the MIRADA-LTERs program (NSF DEB-0717390 to LAZ)