Liquid crystalline properties of type I collagen: Perspectives in tissue morphogenesis

Collagen molecules form the major part of tissues like bone, cornea or tendon where they organize into ordered fibrillar networks. The acid-soluble protein spontaneously assembles in liquid crystalline phases, characterized in polarized light microscopy and X-ray diffraction. Collagen fibrillogenesis obtained in condensed media establishes a link between the fibrillar networks described in vivo and the mesomorphic states obtained in vitro. Cellematrix interactions on these biomimetic materials are currently analysed with perspectives in tissue engineering. In a morphogenetic context, we propose the hypothesis of a liquid crystalline order, between soluble precursor molecules, preceding fibrillogenesis

In vitro studies and preliminary in vivo evaluation of silicified concentrated collagen hydrogels

Hybrid and nanocomposite silicacollagen materials derived from concentrated collagen hydrogels were evaluated in vitro and in vivo to establish their potentialities for biological dressings. Silicification significantly improved the mechanical and thermal stability of the collagen network within the hybrid systems. Nanocomposites were found to favor the metabolic activity of immobilized human dermal fibroblastswhile decreasing the hydrogel contraction. Cell adhesion experiments suggested that in vitro cell behavior was dictated by mechanical properties and surface structure of the scaffold. First-to-date in vivo implantation of bulk hydrogels in subcutaneous sites of rats was performed over the vascular inflammatory period. These materials were colonized and vascularized without inducing strong inflammatory response. These data raise reasonable hope for the future application of silicacollagen biomaterials as biological dressings.Fil: Desimone, Martín Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; ArgentinaFil: Hélary, Christophe. Université Pierre et Marie Curie; FranciaFil: Quignard, Sandrine. Université Pierre et Marie Curie; FranciaFil: Rietveld, Ivo B. Universite de Paris; FranciaFil: Bataille, Clement. Université de Versailles Saint-quentin-en-yvelines.; FranciaFil: Copello, Guillermo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; ArgentinaFil: Mosser, Gervaise. Université Pierre et Marie Curie; FranciaFil: Giraud Guille, Marie-Madeleine. Université Pierre et Marie Curie; FranciaFil: Livage, Jacques. Université Pierre et Marie Curie; FranciaFil: Meddahi Pellé, Anne. Université de Versailles Saint-quentin-en-yvelines.; FranciaFil: Coradin, Thibaud. Université Pierre et Marie Curie; Franci

A simple dynamic model explains the diversity of island birds worldwide

International audienc

A conceptual framework for the vehicle-to-grid (V2G) implementation

The paper focuses on presenting a proposed framework to effectively integrate the aggregated battery vehicles into the grid as distributed energy resources to act as controllable loads to levelize the demand on the system during off-peak conditions and as a generation/storage device during the day to provide capacity and energy services to the grid. The paper also presents practical approaches for two key implementation steps - computer/communication/control network and incentive program.Power systems Electric vehicles Smart grid

Financial Literacy and Numeracy

URL des documents de travail : https://centredeconomiesorbonne.cnrs.fr/publications/Voir aussi le chapitre d'ouvrage basé sur ce document de travail paru dans "The Routledge Hanbook of Financial Literacy", 2021Document de travail du Centre d'Economie de la Sorbonne 2021.31 - ISSN : 1955-611XThe aim of this chapter is to investigate the relationship between financial literacy and numeracy. It turns out that numeracy and financial literacy are strongly correlated. In order to clarify this relationship, we review, in a first section, the general definition of numeracy and its most commonly used measures. We then try to enlighten the distinction that can be made between numeracy and financial literacy. In a second section, we focus on the relationship between numeracy and financial literacy using the main empirical studies performed. Since the analyses of their results show that numeracy is a key determinant of financial literacy, we highlight, in a third and final section, the key role that numeracy could have in education programs and consumer protection policies to improve financial decisions

Financial Literacy and Numeracy

URL des documents de travail : https://centredeconomiesorbonne.cnrs.fr/publications/Voir aussi le chapitre d'ouvrage basé sur ce document de travail paru dans "The Routledge Hanbook of Financial Literacy", 2021Document de travail du Centre d'Economie de la Sorbonne 2021.31 - ISSN : 1955-611XThe aim of this chapter is to investigate the relationship between financial literacy and numeracy. It turns out that numeracy and financial literacy are strongly correlated. In order to clarify this relationship, we review, in a first section, the general definition of numeracy and its most commonly used measures. We then try to enlighten the distinction that can be made between numeracy and financial literacy. In a second section, we focus on the relationship between numeracy and financial literacy using the main empirical studies performed. Since the analyses of their results show that numeracy is a key determinant of financial literacy, we highlight, in a third and final section, the key role that numeracy could have in education programs and consumer protection policies to improve financial decisions

Prédiction des courants de foudre sur les assemblages de fixation d'un réservoir de carburant d'avion avec des méthodes d'apprentissage automatique

An important challenge for the aircraft industry consists to predict the currents on the fastening assemblies in order to avoid sparking, which can lead to accident, especially for fuel tank fasteners. In the literature, it has been demonstrated that the contact resistance plays a major role in the current path on fasteners. Nevertheless, these contact resistances cannot be well determined and vary greatly. As a result, the prediction of current must be done in a statistical way. Usually, it requires several aircraft simulations with several set of contact resistances, which represents a significant computational cost. This article proposes a machine learning model, which allows us to predict the currents in the fastening assemblies of an aircraft fuel tank in a few seconds. This model is built from a database of FDTD simulations of the aircraft fuel tank in the lightning frequency range 100 Hz to 1 MHz. The FDTD modeling is depicted in detail in this article based on previous work. From this database, several machine leaning approaches are explored (k-nearest neighbors, support vector regression, XGBoost, and a neural network). As a result of this study, XGBoost presents the best performances. Further investigations using XGBoost highlights the ability of the model to predict well the current for most fasteners and frequencies, even with a small amount of simulations as training data. Moreover, the proposed model allows us to perform a parametric analysis, which underline the ability of the model to provide results in agreement with the physical effects of the issue (current paths, resistive effects, inductive effects, etc.). The results presented are promising for the use of the proposed methodology in the aeronautical industry.Un défi important pour l'industrie aéronautique consiste à prévoir les courants sur les assemblages de fixation afin d'éviter les étincelles, qui peuvent conduire à un accident, en particulier pour les fixations des réservoirs de carburant. Dans la littérature, il a été démontré que la résistance de contact joue un rôle majeur dans le cheminement du courant sur les fixations. Néanmoins, ces résistances de contact ne peuvent pas être bien déterminées et varient considérablement. Par conséquent, la prédiction du courant doit être effectuée de manière statistique. Habituellement, cela nécessite plusieurs simulations d'avions avec plusieurs ensembles de résistances de contact, ce qui représente un coût de calcul important. Cet article propose un modèle d'apprentissage automatique, qui permet de prédire les courants dans les assemblages de fixation d'un réservoir de carburant d'avion en quelques secondes. Ce modèle est construit à partir d'une base de données de simulations FDTD du réservoir de l'avion dans la gamme de fréquence de la foudre de 100 Hz à 1 MHz. La modélisation FDTD est décrite en détail dans cet article sur la base de travaux antérieurs. À partir de cette base de données, plusieurs approches d'apprentissage automatique sont explorées (k-voisins les plus proches, régression vectorielle de soutien, XGBoost et réseau neuronal). À l'issue de cette étude, c'est XGBoost qui présente les meilleures performances. D'autres études utilisant XGBoost mettent en évidence la capacité du modèle à prédire correctement le courant pour la plupart des fixations et des fréquences, même avec une petite quantité de simulations comme données d'entraînement. En outre, le modèle proposé nous permet d'effectuer une analyse paramétrique, qui souligne la capacité du modèle à fournir des résultats en accord avec les effets physiques de la question (chemins de courant, effets résistifs, effets inductifs, etc.) Les résultats présentés sont prometteurs pour l'utilisation de la méthodologie proposée dans l'industrie aéronautique

Money illusion, financial literacy and numeracy: experimental evidence

International audienc

Comparaison de deux séances d’un dispositif préventif visant la préparation à la modélisation d’une situation-problème

International audienc

Impact and control of feral cats preying on wandering albatrosses: Insights from a field experiment

International audienceInvasive alien species are a major threat to seabird species, and the number of impacted species is still increasing. A recent study revealed for the first time that feral cats predated a large albatross species and that without cat control, some albatross populations would markedly decline. We examined this new predator–prey system by individually monitoring known-age wandering albatross chicks with camera traps in a colony experimentally divided into zones with and without cat control. Our design allowed us to investigate how cat control influenced cat abundance and how this in turn influenced the probability for a chick to be predated by a cat. After cat controls, cat abundance was lower in controlled zones than in uncontrolled zones, while a survival analysis showed that the probability for a chick to die from cat predation depended on the zone but not on cat abundance. Our monitoring also provided a fine-scale investigation of the various sources of chick mortality. In addition to cat predation (24% of mortality overall), our data documented predation by giant petrels, for the first time in Kerguelen, and revealed a strong and unexpected effect of nest flooding on chick mortality. Overall, our results underline the need for future studies investigating interindividual variability in cat diet and spatial ecology