94 research outputs found
Vortex patterns in a fast rotating Bose-Einstein condensate
For a fast rotating condensate in a harmonic trap, we investigate the
structure of the vortex lattice using wave functions minimizing the Gross
Pitaveskii energy in the Lowest Landau Level. We find that the minimizer of the
energy in the rotating frame has a distorted vortex lattice for which we plot
the typical distribution. We compute analytically the energy of an infinite
regular lattice and of a class of distorted lattices. We find the optimal
distortion and relate it to the decay of the wave function. Finally, we
generalize our method to other trapping potentials
Nonclassical rotational inertia for a supersolid under rotation
As proposed by Leggett [4], the supersolidity of a crystal is characterized
by the Non Classical Rotational Inertia (NCRI) property. Using a model of
quantum crystal introduced by Josserand, Pomeau and Rica [5], we prove that
NCRI occurs. This is done by analyzing the ground state of the aforementioned
model, which is related to a sphere packing problem, and then deriving a
theoretical formula for the inertia momentum. We infer a lower estimate for the
NCRI fraction, which is a landmark of supersolidity
Supersolid under rotation and sphere packing problem
We use the model proposed by Josserand, Pomeau, Rica to prove properties on the ground state of a supersolid crystal and relate it to a sphere packing problem. This allows us to find, in the limit of small rotation, an approximate theoretical value for the reduction of the moment of inertia of a supersolid set in rotation, with respect to its classical value
Estimation des aberrations d'un télescope optique par diversité de phase
Cet article est consacré à l'estimation des aberrations optiques d'un télescope spatial d'observation de la Terre par diversité de phase. Deux estimateurs sont présentés et comparés à l'aide de simulations. Le premier, déjà utilisé dans la littérature, repose sur la recherche conjointe des aberrations et de l'objet observé par maximisation de la vraisemblance généralisée. Le second est un nouvel estimateur que nous proposons, basé sur la recherche des aberrations seules par maximum de vraisemblance
Vortex distribution in the Lowest Landau Level
We study the vortex distribution of the wave functions minimizing the Gross
Pitaevskii energy for a fast rotating condensate in the Lowest Landau Level
(LLL): we prove that the minimizer cannot have a finite number of zeroes thus
the lattice is infinite, but not uniform. This uses the explicit expression of
the projector onto the LLL. We also show that any slow varying envelope
function can be approximated in the LLL by distorting the lattice. This is used
in particular to approximate the inverted parabola and understand the role of
``invisible'' vortices: the distortion of the lattice is very small in the
Thomas Fermi region but quite large outside, where the "invisible" vortices
lie.Comment: 4 pages, 1 figur
An improved reference of the grapevine genome supports reasserting the origin of the PN40024 highly-homozygous genotype
The genome sequence assembly of the diploid and highly homozygous V. vinifera genotype PN40024 serves as the reference for many grapevine studies. Despite several improvements of the PN40024 genome assembly, its current version PN12X.v2 is quite fragmented and only represents the haploid state of the genome with mixed haplotypes. In fact, despite the PN40024 genome is nearly homozygous, it still contains various heterozygous regions. Taking the opportunity of the improvements that long-read sequencing technologies offer to fully discriminate haplotype sequences and considering that several Vitis sp. genomes have recently been assembled with these approaches, an improved version of the reference, called PN40024.v4, was generated.
Through incorporating long genomic sequencing reads to the assembly, the continuity of the 12X.v2 scaffolds was highly increased. The number of scaffolds decreased from 2,059 to 640 and the number of N bases was reduced by 88%. Additionally, the full alternative haplotype sequence was built for the first time, the chromosome anchoring was improved and the amount of unplaced scaffolds were reduced by half. To obtain a high-quality gene annotation that outperforms previous versions, a liftover approach was complemented with an optimized annotation workflow for Vitis. Integration of the gene reference catalogue and its manual curation have also assisted in improving the annotation, while defining the most reliable estimation to date of 35,230 genes. Finally, we demonstrate that PN40024 resulted from selfings of cv. ‘Helfensteiner’ (cross of cv. ‘Pinot noir’ and ‘Schiava grossa’) instead of a single ‘Pinot noir’. These advances will help maintaining the PN40024 genome as a gold-standard reference also contributing in the eventual elaboration of the grapevine pangenome.Unpublishe
Preclinical proof of concept of a tetravalent lentiviral T-cell vaccine against dengue viruses
Dengue virus (DENV) is responsible for approximately 100 million cases of dengue fever annually, including severe forms such as hemorrhagic dengue and dengue shock syndrome. Despite intensive vaccine research and development spanning several decades, a universally accepted and approved vaccine against dengue fever has not yet been developed. The major challenge associated with the development of such a vaccine is that it should induce simultaneous and equal protection against the four DENV serotypes, because past infection with one serotype may greatly increase the severity of secondary infection with a distinct serotype, a phenomenon known as antibody-dependent enhancement (ADE). Using a lentiviral vector platform that is particularly suitable for the induction of cellular immune responses, we designed a tetravalent T-cell vaccine candidate against DENV (“LV-DEN”). This vaccine candidate has a strong CD8+ T-cell immunogenicity against the targeted non-structural DENV proteins, without inducing antibody response against surface antigens. Evaluation of its protective potential in the preclinical flavivirus infection model, i.e., mice knockout for the receptor to the type I IFN, demonstrated its significant protective effect against four distinct DENV serotypes, based on reduced weight loss, viremia, and viral loads in peripheral organs of the challenged mice. These results provide proof of concept for the use of lentiviral vectors for the development of efficient polyvalent T-cell vaccine candidates against all DENV serotypes
Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.
RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)
- …