Portail HAL U-Bordeaux
Not a member yet
125366 research outputs found
Sort by
Génération de modèles de métabolisme basés sur la métabolomique pour les communautés microbiennes
No full textInternational audienceThe generation of genome-wide metabolic networks has become a routine analysis for individual organisms or communities communities. However, these automatically generated metabolic networks are incomplete because they are constructed by based on the combination of gene annotation and reactions available in generic available in generic databases (Metacyc, BIGG, ModelSEED...). These are oriented towards well-known organisms or organisms or model organisms and miss out on important functions secondary metabolism. We propose to combine metabolomic data analysis, metabolic modelling and annotation metabolic modelling and annotation mining to build high-quality models of high quality models of microbial metabolism with the long-term aim of better understanding of microbial communities. In terms of application of the methods to plant microbial communities, we hope that the plant microbial communities, we hope that the newly developed models will provide a better understanding of the process of microbial recruitment by the plant: metabolic functions involved, micro-organisms associated with these functions.La génération de réseaux métaboliques à l'échelle du génome est devenue une analyse de routine pour des organismes individuels ou des communautés. Cependant, ces réseaux métaboliques générés automatiquement sont incomplets car ils sont construits sur la base de la combinaison de l'annotation des gènes et des réactions disponibles dans des bases de données génériques (Metacyc, BIGG, ModelSEED...). Ces bases de données sont orientées vers des organismes bien connus ou des organismes modèles et passent à côté de fonctions importantes du métabolisme secondaire. Nous proposons de combiner l'analyse de données métabolomiques, la modélisation métabolique et l'annotation métabolique et la modélisation métabolique et l'annotation minière pour construire des modèles de haute qualité du métabolisme microbien avec l'objectif à long terme d'une meilleure compréhension des communautés microbiennes. En termes d'application des méthodes aux communautés microbiennes végétales, nous espérons que les modèles nouvellement développés permettront de mieux comprendre le processus de recrutement microbien par la plante : fonctions métaboliques impliquées, micro-organismes associés à ces fonctions
De quoi la littératie de l'Intelligence Artificielle en Éducation aux Médias et à l’Information est-elle le nom ?
No full textInternational audienc
A note on orbifold regularity of canonical metrics
No full textIn this short note, we prove that on a compact Kähler variety X with log terminal singularities and c 1 (X) = 0, any singular Ricci-flat Kähler metric has orbifold singularities in restriction to the orbifold locus of X
Quantifying the sp3/sp2 ratio in functionalized graphene
No full textInternational audienceA major challenge in graphene nanoscience is quantifying the concentration of molecules or atoms grafted onto the graphene surface. Raman spectroscopy, a non-contact optical technique, is well suited to achieve this purpose. However, calibration becomes challenging at low coverage due to the weak signal, and at high coverage due to local fluctuations and large regions that yield no Raman response with visible light excitation. In this work, we propose a tailored continuous model that enables accurate quantification of the concentration of covalently bonded molecules or atoms and incorporates input parameters from quantum chemistry calculations that account for surface modifications. We analyze the intensity ratio of the defect-induced D band over the primary G band, along with their broadenings. This approach is validated through the comparison with both our experimental observations and previously published results on various adatom coverage rates. Good agreement is found for both low coverage rates, where the sizes of distorted and activated regions are derived from calculations, and high coverage rates, where sp 3 -hybridized, Raman-inactive regions are included. A detailed analysis of the electronic modifications induced by chemisorbed atomic hydrogen on the graphene surface enables a nonempirical approach to quantify the coverage rate
Whales and the Microstructure of Bitcoin
No full textThis paper analyzes the influence of Bitcoin whales on price formation through the lens of market microstructure. Whales affect volatility and liquidity not only via large trades but also by sending strong informational signals. Despite a gradual diffusion of ownership and the rise of derivatives, whales remain structurally capable of destabilizing or stabilizing Bitcoin's market dynamics
Associations of plasma persistent organic pollutants with brain atrophy, cognitive decline and risk of dementia in older adults
No full textInternational audiencePersistent Organic Pollutants (POP), including polychlorinated biphenyls (PCBs) and organochlorine pesticides, are established neurotoxicants in experimental models; yet it remains uncertain whether exposures in the general population increase the risk to develop brain aging pathologies. We assessed the prospective associations of plasma POP concentrations with three dementia-related outcomes in a population-based cohort of older adults.MethodsAnalyses included 515 participants from the Three-City Study, free of dementia at baseline at the time of blood measurements (1999–2000, mean age 72.5), who underwent up to 8 repeated assessments of cognitive function and dementia over 17 years and up to 3 neuroimaging examinations over 10 years. Plasma concentrations of 15 PCBs, 12 organochlorine pesticides and 1 brominated flame retardant were measured by gas chromatography coupled with tandem mass spectrometry (detection rate ≥5 %), and a POP score summarizing overall exposure was derived via factorial analysis. Associations with dementia risk, longitudinal changes in cognitive function (composite measure of four tests) and in brain volume (medial temporal lobe) were analyzed using Cox and linear mixed models, adjusted for baseline age, sex, education, apolipoprotein E (APOE) genotype, body mass index and total lipid concentrations.ResultsIn multivariable-adjusted models, neither individual POPs nor the total POP score were significantly and consistently associated with dementia-related outcomes. Significant interactions were observed between APOE genotype and highly-chlorinated PCBs (congeners 180, 194, and 196–203) across all outcomes (p for interaction ≤0.05), whereby adverse associations were seen in carriers of the APOE-ɛ4 allele, whereas opposing trends were observed in non-carriers.ConclusionOverall, this prospective study does not provide robust evidence to support an adverse association between exposure to POPs in the general population and the risk of all-cause dementia, cognitive decline, or brain atrophy in older adults
Efficient Modeling and Rendering of Iridescence from Cholesteric Liquid Crystals
No full textInternational audienceWe introduce a novel approach to the efficient modeling and rendering of Cholesteric Liquid Crystals (CLCs), materials known for producing colorful effects due to their helical molecular structure. CLCs reflect circularly-polarized light within specific spectral bands, making their accurate simulation challenging for realistic rendering in Computer Graphics. Using the two-wave approximation from the Photonics literature, we develop a piecewise spectral reflectance model that improves the understanding of how light interact with CLCs for arbitrary incident angles. Our reflectance model allows for more efficient spectral rendering and fast integration into RGB-based rendering engines. We show that our approach is able to reproduce the unique visual properties of both natural and man-made CLCs, while keeping the computation fast enough for interactive applications and avoiding potential spectral aliasing issues
La trumplang, instrument de destruction de la pensée : analyse de l'impact de la censure trumpiste sur la recherche en santé mentale
No full textNational audienceUn processus de censure de l'activité scientifique est en cours aux États-Unis. À partir de listes de termes interdits, des dossiers de financements sont réétudiés, des articles scientifiques sont rétractés. Or, le langage structure les tranches du réel descriptibles - et donc celles qui peuvent être étudiées scientifiquement. Dans cet article, nous souhaitons afficher comment la mise en place d'une telle censure pourrait provoquer la disparition de la recherche portant sur la santé mentale. Pour cela, nous avons réalisé une analyse bibliographique des 64 434 articles contenant le terme « mental health » dans leur titre référencé dans PubMed. Nous avons ensuite extrait une liste de termes interdits de leur résumé, identifié les thèmes sous-jacents et généré un réseau lexical. Ces résultats démontrent l'impossibilité de penser la santé mentale sans les termes interdits par les directives trumpistes, dont la censure signerait l'abandon de plus de 50 ans de progrès en santé publique