The complex interplay between tidal inertial waves and zonal flows in differentially rotating stellar and planetary convective regions:I. Free waves

Quantifying tidal interactions in close-in two-body systems is of prime interest since they have a crucial impact on the architecture and on the rotational history of the bodies. Various studies have shown that the dissipation of tides in either body is very sensitive to its structure and to its dynamics, like differential rotation which exists in the outer convective enveloppe of solar-like stars and giant gaseous planets. In particular, tidal waves may strongly interact with zonal flows at the so-called corotation resonances, where the wave's Doppler-shifted frequency cancels out. We aim to provide a deep physical understanding of the dynamics of tidal inertial waves at corotation resonances, in the presence of differential rotation profiles typical of low-mass stars and giant planets. By developping an inclined shearing box, we investigate the propagation and the transmission of free inertial waves at corotation, and more generally at critical levels, which are singularities in the governing wave differential equation. Through the construction of an invariant called the wave action flux, we identify different regimes of wave transmission at critical levels, which are confirmed with a one-dimensional three-layer numerical model. We find that inertial waves can be either fully transmitted, strongly damped, or even amplified after crossing a critical level. The occurrence of these regimes depends on the assumed profile of differential rotation, on the nature as well as the latitude of the critical level, and on wave parameters such as the inertial frequency and the longitudinal and vertical wavenumbers. Waves can thus either deposit their action flux to the fluid when damped at critical levels, or they can extract action flux to the fluid when amplified at critical levels. Both situations could lead to significant angular momentum exchange between the tidally interacting bodies.Comment: 25 pages, 12 figures, 4 tables, accepted for publication in Astronomy & Astrophysic

Complex dynamics for the study of neural activity in the human brain

Congrès sous l’égide de la Société Française de Génie Biologique et Médical (SFGBM).National audienceNeural mass modeling is a part of computational neuroscience that was developed to study the general behavior of interacting neuronal populations. This type of mesoscopic model is able to generate output signals that are comparable with experimental data such as electroencephalograms. Classically, neural mass models consider two interconnected populations. One interaction have been modeled in two differents ways. In this work we propose and analyze a neural mass model embedding both approaches and compare the generated time series to real data

Robust Bregman Clustering

International audienceUsing a trimming approach, we investigate a k-means type method based on Bregman divergences for clustering data possibly corrupted with clutter noise. The main interest of Bregman divergences is that the standard Lloyd algorithm adapts to these distortion measures, and they are well-suited for clustering data sampled according to mixture models from exponential families. We prove that there exists an optimal codebook, and that an empirically optimal codebook converges a.s. to an optimal codebook in the distortion sense. Moreover, we obtain the sub-Gaussian rate of convergence for k-means 1 √ n under mild tail assumptions. Also, we derive a Lloyd-type algorithm with a trimming parameter that can be selected from data according to some heuristic, and present some experimental results

Narrow band selected high redshift galaxy candidates contaminated by lower redshift O[III] ultrastrong emitter line galaxies

Context. Lyman Break Galaxies (LBG) and Narrow Band (NB) surveys have been successful at detecting large samples of high-redshift galaxies. Both methods are subject to contamination from low-redshift interlopers. Aims. In this paper, our aim is to investigate the nature of low-redshift interlopers in NB Lyman-$\alpha$ emitters (LAE) searches. Methods. From previous HAWK-I NB imaging at z $\sim$7.7 we identify three objects that would have been selected as high-redshift LAEs had our optical data been one magnitude shallower (but still one to two magnitudes fainter than the near infrared data). We follow-up these objects in spectroscopy with XSHOOTER at the VLT. Results. Despite low quality data due to bad weather conditions, for each of the three objects we identify one, and only one emission line, in the spectra of the objects, that we identify as the O[III]5007A line. This result combined to spectral energy density fitting and tests based on line ratios of several populations of galaxies we infer that the 3 objects are ultrastrong line emitters at redshifts $\sim$1.1. Conclusions. From this work and the literature we remark that the O[III] line appears to be a common source of contamination in high-redshift LBG and LAE samples and we suggest that efforts be put to characterize with high accuracy the O[III] luminosity function out to redshift $\sim$3 or higher.Comment: 7 pages, 4 figures, accepted by A&

Grxcr1 promotes hair bundle development by destabilizing the physical interaction between Harmonin and Sans usher syndrome proteins

© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Cell Reports 25 (2018): 1281–1291, doi:10.1016/j.celrep.2018.10.005.Morphogenesis and mechanoelectrical transduction of the hair cell mechanoreceptor depend on the correct assembly of Usher syndrome (USH) proteins into highly organized macromolecular complexes. Defects in these proteins lead to deafness and vestibular areflexia in USH patients. Mutations in a non-USH protein, glutaredoxin domain-containing cysteine-rich 1 (GRXCR1), cause non-syndromic sensorineural deafness. To understand the deglutathionylating enzyme function of GRXCR1 in deafness, we generated two grxcr1 zebrafish mutant alleles. We found that hair bundles are thinner in homozygous grxcr1 mutants, similar to the USH1 mutants ush1c (Harmonin) and ush1ga (Sans). In vitro assays showed that glutathionylation promotes the interaction between Ush1c and Ush1ga and that Grxcr1 regulates mechanoreceptor development by preventing physical interaction between these proteins without affecting the assembly of another USH1 protein complex, the Ush1c- Cadherin23-Myosin7aa tripartite complex. By elucidating the molecular mechanism through which Grxcr1 functions, we also identify a mechanism that dynamically regulates the formation of Usher protein complexes.This work was supported by grants from the NIH (DC004186, OD011195, and HD22486)

Une <i>culina</i> de type « pompéien » en territoire lyonnais : l’espace culinaire de la <i>villa</i> de Goiffieux à Saint-Laurent-d’Agny (Rhône)

International audienceThe excavations conducted on the site of Goiffieux at Saint-Laurent-d’Agny, between 2008 and 2011, brought to light a vast villa belonging to the colony of Lugdunum and occupied as soon as its foundation in the years 30-40 BC. Mainly devoted to viticulture, this establishment is equipped at the beginning of our era with private baths, associated to a small well-preserved kitchen. In this article functional equipment (hob, bench) are analysed, as well as food waste found in this area (fauna, plant remains and pottery assemblages). The kitchen is linked to water devices that we can identify to a water mill and latrines. Its masonry hob equipped with vault reserves of fuel, and fed by the adjacent praefurnium, is a characteristic of urban culinae known in Campania and there is no equivalent in the Tres Galliae rural space. It attests to a strong influence of Italic architectural patterns, which goes together with the adoption of new culinary practices.Les fouilles menées de 2008 à 2011 sur le site de Goiffieux, à Saint-Laurent-d’Agny, y ont mis au jour une vaste villa rattachée à la colonie de Lugdunum et occupée dès sa phase de fondation, dans les années 30-40 av. J.-C. Principalement dédié à la viticulture, ce domaine de rendement se dote au début de notre ère de bains privés, associés à une petite cuisine aux vestiges bien conservés. Cet article s’intéresse à ses aménagements fonctionnels (table à feu, paillasse) aussi bien qu’aux reliefs alimentaires retrouvés dans cet espace (faune, carporestes et assemblages céramiques). La cuisine est associée à des équipements hydrauliques, que l’on propose d’identifier à un petit moulin hydraulique et à un espace de latrine. Sa table à feu maçonnée, dotée de réserves à combustible voûtées et alimentée par le praefurnium adjacent, est caractéristique des culinae urbaines reconnues en Campanie et ne possède aucun équivalent dans les campagnes des Trois Gaules. Elle témoigne d’une forte influence des modèles architecturaux italiques, qui va de pair avec l’adoption de nouveaux modes de préparation alimentaire

Degradation mechanism of Ti-6Al-2Sn-4Zr-2Mo-Si alloy exposed to solid NaCl deposit at high temperature

This study focuses on the corrosion behaviour of Ti-6Al-2Sn-4Zr-2Mo-Si alloy in presence of NaCl deposit in air at 560 °C. The active oxidation mechanism at the origin of the corrosion phenomenon enhancement in presence of solid NaCl is thought to be connected to the formation of both external and internal thick oxidation areas. Thermodynamic calculations allowed showing the role played by the different alloying elements in the forma-tion of the external oxide and detailed TEM characterisations brought new insights regarding the nature and origin of the internal oxidation area