Portail HAL U-Bordeaux
Not a member yet
125366 research outputs found
Sort by
Répercussions de la Peste noire sur l’alimentation à la fin du Moyen Âge : nouvelles données issues d’analyses isotopiques d’ensembles funéraires toulousains
No full textInternational audienceLa Peste noire (1347-1352), en raison notamment de l’important déclin démographique qu’elle a causé, a eu des répercussions socio-économiques majeures sur les sociétés de la fin du Moyen Âge. Selon certains historiens, elle aurait indirectement conduit à une amélioration des conditions de vie des classes laborieuses, et en particulier de leur alimentation. Afin de tester cette hypothèse, nous avons réalisé des analyses des isotopes stables du carbone (δ13C) et de l’azote (δ15N) sur un corpus de 172 échantillons osseux issus de séries médiévales toulousaines, collectés sur les squelettes de victimes de la Peste noire (1348, n=47) et d’individus morts avant (1330-1334, n=69) et après cette épidémie (1380-1545, n=56). Aucune différence significative n’a été observée entre les signatures isotopiques des sujets morts avant (δ13C=-19,1±0,3 ‰ ; δ15N=11,3±0,9 ‰) et pendant la Peste noire (δ13C=-19,2±0,4 ‰ ; δ15N=11,2±0,7 ‰), ce qui témoigne d’un régime alimentaire comparable entre les deux groupes. A contrario, les individus morts après l’épidémie se différencient par des valeurs en δ13C et δ15N plus élevées (respectivement -18,8±0,3 ‰ et 11,7±0,7 ‰). Ces résultats indiquent une diversification du régime alimentaire dans les décennies qui ont suivi l’épidémie, marquée par une consommation accrue de protéines d’origine animale (terrestre ou marine), possiblement couplée à l’introduction de plantes en C4 dans l’alimentation. L’augmentation des valeurs de δ15N est en outre plus forte chez les sujets féminins, dont les apports en protéines d’origine animale, inférieurs à ceux dont bénéficiaient les hommes avant l’épidémie, s’en rapproche après celle-ci. Dans l’ensemble, l’étude révèle d’importants changements de régimes alimentaires après la Peste noire et soulève d’intéressantes questions quant à ses effets sur l’inégalité d’accès aux ressources alimentaires selon le sexe
Plasmodesmata act as unconventional membrane contact sites regulating intercellular molecular exchange in plants
No full textInternational audienceMembrane contact sites (MCSs) are fundamental for intracellular communication, but their role in intercellular communication remains unexplored. We show that in plants, plasmodesmata communication bridges function as atypical endoplasmic reticulum (ER)-plasma membrane (PM) tubular MCSs, operating at cell-cell interfaces. Similar to other MCSs, ER-PM apposition is controlled by a protein-lipid tethering complex, but uniquely, this serves intercellular communication. Combining high-resolution microscopy, molecular dynamics, and pharmacological and genetic approaches, we show that cell-cell trafficking is modulated through the combined action of multiple C2 domains transmembrane domain proteins (MCTPs) 3, 4, and 6 ER-PM tethers and phosphatidylinositol-4-phosphate (PI4P) lipid. Graded PI4P amounts regulate MCTP docking to the PM, their plasmodesmata localization, and cell-cell permeability. SAC7, an ER-localized PI4P-phosphatase, regulates MCTP4 accumulation at plasmodesmata and modulates cell-cell trafficking capacity in a cell-type-specific manner. Our findings expand MCS functions in information transmission from intracellular to intercellular cellular activities
Imagerie(s) synchrotron et patrimoine archéologique : potentiels, bonnes pratiques et limites
No full textInternational audienc
Elliptic butterflies
No full textWe study natural evaluation and interpolation problems for elliptic functions and prove that they allow a recursive treatment using a variant of classical butterflies first introduced by Gauss. We deduce the existence of straight-line programs with complexity in d log(d) for these problems and present applications to finite field arithmetic, coding theory and cryptography
H.E.S.S. programme searching for VHE gamma rays associated with FRBs
No full textInternational audienceFast Radio Bursts (FRBs) are highly energetic, extremely short-lived bursts of radio flashes. Despite extensive research, the exact cause of these outbursts remains speculative. The high luminosity, short duration, and high dispersion measure of these events suggest they result from extreme, high-energy extragalactic sources, such as highly magnetized and rapidly spinning neutron stars known as magnetars. The number of detected FRBs, including repeating ones, has grown rapidly in recent years. Except for FRB 20200428D, and FRB-like radio burst that is associated to Galactic magnetar SGR 1935+2154, no multi-wavelength counterpart to any FRB has been detected yet. The High Energy Stereoscopic System (H.E.S.S.) telescope has developed a {program} to follow up FRBs searching for their gamma-ray counterparts, helping to uncover the nature of FRBs and FRB sources. This paper provides an overview of the searches for FRB sources conducted by H.E.S.S., including follow-up observations and simultaneous multi-wavelength campaigns with radio and X-ray observatories. Among the FRB sources observed by H.E.S.S., nine are localized with redshifts ranging between 0.11 and 0.492 from 2015 to 2022. No significant very high energy (VHE) emission was detected during these observations. We report constraints on the VHE luminosity ranging from erg s and erg s, placing limits on the FRB's region persistent VHE emission and potential FRB afterglow emission across timescales from hours to years
Quantifying the relative contributions of forcings to the variability of estuarine surface suspended sediments using a machine learning framework
No full textInternational audienceThe influence of forcing mechanisms on the variability of suspended sediments in an estuary is, for the first time, synoptically quantified over prevailing ('normal') conditions and extreme events. This study investigates the complex and non-linear influence of tides, river discharge, and winds on the variability of suspended sediments in the macrotidal Gironde Estuary, France. Employing a machine learning-based framework, we integrated high-frequency field data, hourly numerical modeling outputs, and semi-daily satellite remote sensing to spatially quantify the relative contributions of forcing mechanisms. Our results reveal that tides are the primary driver of sediment variability (42.3–58.9%), followed by river discharge (21.2–34.7%) and wind (8.7–16.9%). Uncertainties range between 7% and 13.6%. In addition, the spatial variability of their contributions is consistent across numerical modeling and satellite remote sensing data, with differences not exceeding 10%. However, satellite data is limited by cloud cover and may miss extreme events. In contrast, hourly numerical modeling indicates tides are the dominant forcing mechanism under extreme events significantly affecting suspended sediment variability in the estuary. This study verifies the effectiveness of our machine learning approach against traditional Singular Spectral Analysis using field data. We demonstrate that machine learning techniques can effectively synthesize spatial distribution patterns of hydrodynamic and sedimentological variability, including the influence of winds. Our findings highlight not only the potential of satellite observations to analyze prevailing conditions despite data gaps but also that with hourly numerical modeling, the impact of forcings can be synoptically quantified under prevailing ('normal') conditions and extreme events
Vers un « nouvel équilibre » familial ? L’égalité de genre et les représentations de la parentalité en France et en Suède
No full textInternational audienceLa théorie du « nouvel équilibre », proposée par Gøsta Esping-Andersen et Francesco Billari en 2015, suggère que l’égalité de genre extensive, c’est-à-dire dans la sphère professionnelle et dans la sphère domestique, contribue à rendre la parentalité plus attractive. Mais cette relation semble varier selon les contextes et s’observe apparemment surtout dans les pays nordiques. À partir des données de l’enquête ISSP 2012, l’article met à l’épreuve cette théorie en examinant la relation entre l’égalité de genre et les représentations de la parentalité en France et en Suède. En Suède, où les pratiques domestiques sont plus égalitaires, l’égalité dans le couple est associée à des perceptions moins négatives de la parentalité, soutenant l’idée d’un renouveau des relations familiales. En revanche, en France, aucune association n’est observée ; les représentations parentales restent plus pessimistes, quel que soit le niveau d’égalité dans les couples. L’étude met en lumière le rôle des politiques nationales. Les politiques suédoises, qui favorisent le partage des congés parentaux, encouragent ainsi des modèles de coresponsabilité et une vision positive de la parentalité. Au contraire, en France, le soutien limité à l’enrôlement paternel semble entraver la possibilité d’une dynamique similaire
Accurate MAG reconstruction from complex soil microbiome through combined short- and HiFi long-reads metagenomics
No full textBackground: Advances in high-fidelity long-read (HiFi-LR) sequencing technologies offer unprecedented opportunities to uncover the microbial genomic diversity of complex environments, such as soils. While short-read (SR) sequencing has enabled broad insights at gene-level diversity, the inherently limited read length constrains the reconstruction of complete genomes. Conversely, HiFi-LR sequencing enhances the quality and completeness of metagenome-assembled genomes (MAGs), enabling higher-resolution taxonomic and functional annotation. However, the cost and relatively low throughput of HiFi-LR sequencing can limit genome recovery, particularly at the binning stage, where coverage depth is critical. Results: Here, we present a novel hybrid strategy that differs from classical hybrid assemblies, where SR and LR reads are jointly used at the assembly step. Instead, we use high-depth SR data to improve the binning of HiFi-LR contigs. Using both SR and HiFi-LR metagenomic data generated from a tunnel-cultivated soil sample, we demonstrate that SR-derived coverage information significantly improves the binning of HiFi-LR assemblies. This results in a substantial increase in the number and quality of recovered MAGs compared to using HiFi-LR data alone and an incomparable improvement compared to SR data alone. Conclusion: Our findings highlight the power of combining SR and LR in highly diverse environments, such as soil, not for hybrid assembly per se, but to enhance the downstream binning process. The combination of SR and LR data substantially improves the downstream binning process and overall genome recovery. Importantly, this approach underscores the potential of leveraging the vast amount of publicly available Illumina metagenomic datasets. Completing existing SR resources with PacBio HiFi sequencing can maximise assembly contiguity and binning accuracy using massive amounts of SR data already generated. This highlights a practical and forward-looking strategy for microbiome research, where novel LR technologies will bring new value to previous short-read efforts
Collagen-Based Gut-on-Chip for in vitro modeling of intestinal barrier function and host-pathogen interactions
No full textAbstract The human intestine, characterized by its villi and crypt structures, plays a critical role in nutrient absorption, barrier function, and host defense. However, traditional in-vitro models employing synthetic membranes like polydimethylsiloxane (PDMS) and polycarbonate (PC) often fail to accurately replicate the complex physiological environment of the intestine. To address this limitation, we developed a gut-on-chip, incorporating a porous collagen type I membrane, to better mimic the natural extracellular matrix (ECM) and create a more physiologically relevant in vitro system. Thin, porous collagen type I membranes were fabricated and characterized by linear close contact profilometry to determine their thickness, which closely approximated the in vivo intestinal basement membrane. Caco-2 cells cultured within the device exhibited the formation of villi-like structures, tight junction formation, and mucin production, demonstrating successful differentiation and functional barrier formation on the collagen membrane. We investigated the device’s capacity to model host-pathogen interactions by infecting the cell layer with Candida albicans . Confocal microscopy revealed hyphal invasion of the epithelial cells, and permeability assays demonstrated increased layer permeability following infection, highlighting the device’s ability to replicate infection processes and their impact on barrier integrity. This gut-on-chip, by integrating physiological membrane and replicating key structural and functional aspects of the intestine, offers a promising platform for studying intestinal physiology and host-pathogen dynamics
