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/)

Modélisation interactive de formes 3D bio-inspirées évolutives et émergentes.

Due to manufacturing constraints, Computer-Aided Design has primarily focused on combinations of mathematical functions and simple parametric forms. However, the landscape changed with the advent of 3D printing, which allows for high shape complexity. The cost of additive manufacturing is now dominated by part size and material used rather than complexity, paving the way for a reevaluation of 3D modeling practices, including interactive conception and increased complexity.Inspired by the self-organizing principles observed in living organisms, the field of morphogenesis presents an intriguing alternative for 3D modeling. Unlike traditional CAD systems relying on explicit user-defined parameters, morphogenetic models leverage dynamic processes that exhibit emergence, evolution, adaptation to the environment, or self-healing.The general purpose of this Ph.D. is to explore and develop new approaches to 3D modeling based on highly detailed evolutionary shapes inspired by morphogenesis. The thesis commences with an in-depth exploration of bio-inspired 3D modeling, encompassing various methodologies, challenges, and options for incorporating bio-inspired concepts into 3D modeling practices.Subsequent chapters delve into specific morphogenesis models.In the first part, the focus extends to adapting a biologically inspired model, specifically Physarum polycephalum, into computer graphics for designing organic-like microstructures. This section offers a comprehensive methodological development, analyzes model parameters, and discusses potential applications in diverse fields such as additive manufacturing, design, and biology.In the second part, a novel approach is investigated, utilizing Reaction/Diffusion models to grow lattice-like and membrane-like structures within arbitrary shapes. The methodology is based on anisotropic Reaction-Diffusion systems and diffusion tensor fields, demonstrating applications in mechanical properties, validation through nonlinear analysis, user interaction, and scalability.Finally, the third part explores the application of deep learning techniques to learn the rules of morphogenesis processes, specifically Reaction/Diffusion. It begins by illustrating the richness offered by Reaction/Diffusion systems before delving into the training of Cellular Automata and Reaction/Diffusion rules to learn system parameters, resulting in robust and "life-like" behaviors.En raison de contraintes de fabrication, la Conception Assistée par Ordinateur (CAO) s'est principalement concentrée sur des combinaisons de fonctions mathématiques et de formes paramétriques simples. Cependant, ceci a changé avec l'avènement de l'impression 3D, qui permet désormais de manufacturer simplement des pièces topologiquemnt complexes. Le coût de la fabrication additive est désormais déterminé par la taille de la pièce et le matériau utilisé plutôt que par sa complexité, ouvrant la voie à une réévaluation des pratiques de modélisation 3D, incluant la conception interactive et complexe.Inspiré par les principes d'auto-organisation observés dans les organismes vivants, le domaine de la morphogenèse présente une alternative intéressante pour la modélisation 3D. Contrairement aux systèmes CAO traditionnels reposant sur des paramètres explicites définis par l'utilisateur, les modèles morphogénétiques exploitent des processus dynamiques tels que l'émergence, l'évolution, l'adaptation à l'environnement ou l'auto-guérison.Le but général de cette thèse est d'explorer et de développer de nouvelles approches de modélisation 3D basées sur des formes évolutives hautement détaillées inspirées par la morphogenèse. La thèse commence par une exploration approfondie de la modélisation 3D bio-inspirée, englobant diverses méthodologies, défis et possibilités pour incorporer des concepts bio-inspirés dans les pratiques de modélisation 3D.Les chapitres suivants se penchent sur des modèles spécifiques de morphogenèse.La première partie étudie comment adapter un modèle biologiquement inspiré, extit{Physarum polycephalum}, au domaine d'informatique graphique, dans le but de concevoir des microstructures organiques. Ce chapitre propose une étude méthodologique complète, analyse les paramètres du modèle et discute des applications potentielles dans divers domaines tels que la fabrication additive, le design et la biologie.Dans la deuxième partie, une nouvelle approche est étudiée, utilisant un modèle de réaction/diffusion pour faire croître des structures lattice et membranes à l'intérieur de formes arbitraires. La méthode se base sur des systèmes de réaction-diffusion anisotropes et des champs de tenseurs de diffusion, et démontre de remarquables propriétés mécaniques pour les structures générées, validées par analyse non linéaire. Cette approche est scalable au grand volume et permet une interactivité utilisateur en temps réel.Enfin, la troisième partie explore l'application de techniques d'apprentissage profond pour apprendre les règles des processus de morphogenèse, en particulier ceux de réaction/diffusion. Elle commence par illustrer la richesse offerte par les systèmes de réaction/diffusion avant de se plonger dans l'entraînement d'automates cellulaires et de règles de réaction/diffusion pour apprendre les paramètres de ces systèmes. Ces derniers se révèlent être robustes et montrent un comportement très semblable au vivant

Modélisation interactive de formes 3D bio-inspirées évolutives et émergentes.

Due to manufacturing constraints, Computer-Aided Design has primarily focused on combinations of mathematical functions and simple parametric forms. However, the landscape changed with the advent of 3D printing, which allows for high shape complexity. The cost of additive manufacturing is now dominated by part size and material used rather than complexity, paving the way for a reevaluation of 3D modeling practices, including interactive conception and increased complexity.Inspired by the self-organizing principles observed in living organisms, the field of morphogenesis presents an intriguing alternative for 3D modeling. Unlike traditional CAD systems relying on explicit user-defined parameters, morphogenetic models leverage dynamic processes that exhibit emergence, evolution, adaptation to the environment, or self-healing.The general purpose of this Ph.D. is to explore and develop new approaches to 3D modeling based on highly detailed evolutionary shapes inspired by morphogenesis. The thesis commences with an in-depth exploration of bio-inspired 3D modeling, encompassing various methodologies, challenges, and options for incorporating bio-inspired concepts into 3D modeling practices.Subsequent chapters delve into specific morphogenesis models.In the first part, the focus extends to adapting a biologically inspired model, specifically Physarum polycephalum, into computer graphics for designing organic-like microstructures. This section offers a comprehensive methodological development, analyzes model parameters, and discusses potential applications in diverse fields such as additive manufacturing, design, and biology.In the second part, a novel approach is investigated, utilizing Reaction/Diffusion models to grow lattice-like and membrane-like structures within arbitrary shapes. The methodology is based on anisotropic Reaction-Diffusion systems and diffusion tensor fields, demonstrating applications in mechanical properties, validation through nonlinear analysis, user interaction, and scalability.Finally, the third part explores the application of deep learning techniques to learn the rules of morphogenesis processes, specifically Reaction/Diffusion. It begins by illustrating the richness offered by Reaction/Diffusion systems before delving into the training of Cellular Automata and Reaction/Diffusion rules to learn system parameters, resulting in robust and "life-like" behaviors.En raison de contraintes de fabrication, la Conception Assistée par Ordinateur (CAO) s'est principalement concentrée sur des combinaisons de fonctions mathématiques et de formes paramétriques simples. Cependant, ceci a changé avec l'avènement de l'impression 3D, qui permet désormais de manufacturer simplement des pièces topologiquemnt complexes. Le coût de la fabrication additive est désormais déterminé par la taille de la pièce et le matériau utilisé plutôt que par sa complexité, ouvrant la voie à une réévaluation des pratiques de modélisation 3D, incluant la conception interactive et complexe.Inspiré par les principes d'auto-organisation observés dans les organismes vivants, le domaine de la morphogenèse présente une alternative intéressante pour la modélisation 3D. Contrairement aux systèmes CAO traditionnels reposant sur des paramètres explicites définis par l'utilisateur, les modèles morphogénétiques exploitent des processus dynamiques tels que l'émergence, l'évolution, l'adaptation à l'environnement ou l'auto-guérison.Le but général de cette thèse est d'explorer et de développer de nouvelles approches de modélisation 3D basées sur des formes évolutives hautement détaillées inspirées par la morphogenèse. La thèse commence par une exploration approfondie de la modélisation 3D bio-inspirée, englobant diverses méthodologies, défis et possibilités pour incorporer des concepts bio-inspirés dans les pratiques de modélisation 3D.Les chapitres suivants se penchent sur des modèles spécifiques de morphogenèse.La première partie étudie comment adapter un modèle biologiquement inspiré, extit{Physarum polycephalum}, au domaine d'informatique graphique, dans le but de concevoir des microstructures organiques. Ce chapitre propose une étude méthodologique complète, analyse les paramètres du modèle et discute des applications potentielles dans divers domaines tels que la fabrication additive, le design et la biologie.Dans la deuxième partie, une nouvelle approche est étudiée, utilisant un modèle de réaction/diffusion pour faire croître des structures lattice et membranes à l'intérieur de formes arbitraires. La méthode se base sur des systèmes de réaction-diffusion anisotropes et des champs de tenseurs de diffusion, et démontre de remarquables propriétés mécaniques pour les structures générées, validées par analyse non linéaire. Cette approche est scalable au grand volume et permet une interactivité utilisateur en temps réel.Enfin, la troisième partie explore l'application de techniques d'apprentissage profond pour apprendre les règles des processus de morphogenèse, en particulier ceux de réaction/diffusion. Elle commence par illustrer la richesse offerte par les systèmes de réaction/diffusion avant de se plonger dans l'entraînement d'automates cellulaires et de règles de réaction/diffusion pour apprendre les paramètres de ces systèmes. Ces derniers se révèlent être robustes et montrent un comportement très semblable au vivant

Growing Optimized Anisotropic Microstructures with Reaction/Diffusion

National audienceLattice structures can present advantageous mechanical properties while remaining remarkably lightweight. Precise lattice design can however be tricky to set up on arbitrary domain with classical 3D modeling methods as it involves very fine oriented details. Interestingly, natural porous structures can present such lattice-like design which motivates the seek for bio-inspired approaches. In this paper we present a novel method to grow lattice-like structures within an arbitrary shape and aligned along an oriented field using adapted Reaction/Diffusion systems. While not directly computed from a global optimization process our structures still demonstrate remarkable structural properties for which we provide examples with numerical validation

Growth of oriented orthotropic structures with reaction/diffusion

International audienceLattice structures can present advantageous mechanical properties while remaining remarkably lightweight. Precise lattice design can however be tricky to set up with classical 3D modeling methods as it involves very fine details. Interestingly, natural porous structures can present such latticelike or membrane-like features which motivates to seek for more bio-inspired approaches to microstructure design. In this paper we present a novel method to grow lattice-like and membrane-like structures within an arbitrary shape and aligned along an oriented field. Our method relies on the use of a dedicated anisotropic Reaction-Diffusion system guided by an orthotropic diffusion tensor field. Assuming for instance the diffusion tensor to be related to the stress analysis of a given shape allows to generate emerging stripes patterns aligned along each one of the principal stress directions independently. A globally coherent mechanical model conforming to the initial shape boundary and infilled with oriented microstructures can therefore be synthesized. Further, we demonstrate the capability of this approach to handle other types of oriented fields such as obtained through optimization of material directions in scenarios with multiple load-cases. Our approach relies on spatially and temporally local operations allowing for efficient parallelization. This permits user-interaction and automated adaptation of the design, even for fine meshes over large volumes. For instance, a designer can locally erase or "draw" over the structure and let it regrow and adapt as well as enforce regions to be deliberately full or empty. The proposed approach yields smooth and conformal oriented anisotropic geometrical patterns. This is related to recent effort in the Structural Optimization community on the topic of optimized oriented infills and microstructure de-homogenization. One of the resulting designs is validated by means of a full scale general nonlinear analysis showcasing the advantageous properties of oriented microstructures for stability and robustness to buckling

PhysOM: Physarum polycephalum Oriented Microstructures

International audienceBiological shapes possess fascinating properties and behaviours that are the result of emergent mechanisms: they can evolve over time, dynamically adapt to changes in their environment, while also exhibiting interesting mechanical properties and aesthetic appeal. In this work, we bring and extend an existing biological‐inspired model of the Physarum polycephalum , aka the blob , to the field of computer graphics, in order to design porous organic‐like microstructures that resemble natural foam‐like cells or filament‐like patterns with variable local properties. In contrast to approaches based on static global optimization that provides only limited expressivity over the result, our method allows precise control over the local orientation of 3D patterns, relative cell extension and precise infill of shapes with well defined boundaries. To this end, we extend the classical agent‐based model for Physarum to fill an arbitrary domain with local anisotropic behaviour. We further provide a detailed analysis of the model parameters, contributing to the understanding of the system behaviour. The method is fast, parallelizable and scalable to large volumes and compatible with user interaction, allowing a designer to guide the structure, erase parts and observe its evolution in real‐time. Overall, our method provides a versatile and efficient means of generating intricate organic microstructures that have potential applications in fields such as additive manufacturing, design or biological representation and engineering

The Paris Agreement objectives will likely halt future declines of emperor penguins

International audienceThe Paris Agreement is a multinational initiative to combat climate change by keeping a global temperature increase in this century to 2°C above preindustrial levels while pursuing efforts to limit the increase to 1.5°C. Until recently, ensembles of coupled climate simulations producing temporal dynamics of climate en route to stable global mean temperature at 1.5 and 2°C above preindustrial levels were not available. Hence, the few studies that have assessed the ecological impact of the Paris Agreement used ad-hoc approaches. The development of new specific mitigation climate simulations now provides an unprecedented opportunity to inform ecological impact assessments. Here we project the dynamics of all known emperor penguin (Aptenodytes forsteri) colonies under new climate change scenarios meeting the Paris Agreement objectives using a climate-dependent-metapopulation model. Our model includes various dispersal behaviors so that penguins could modulate climate effects through movement and habitat selection. Under business-as-usual greenhouse gas emissions, we show that 80% of the colonies are projected to be quasiextinct by 2100, thus the total abundance of emperor penguins is projected to decline by at least 81% relative to its initial size, regardless of dispersal abilities. In contrast, if the Paris Agreement objectives are met, viable emperor penguin refuges will exist in Antarctica, and only 19% and 31% colonies are projected to be quasiextinct by 2100 under the Paris 1.5 and 2 climate scenarios respectively. As a result, the global population is projected to decline by at least by 31% under Paris 1.5 and 44% under Paris 2. However, population growth rates stabilize in 2060 such that the global population will be only declining at 0.07% under Paris 1.5 and 0.34% under Paris 2, thereby halting the global population decline. Hence, global climate policy has a larger capacity to safeguard the future of emperor penguins than their intrinsic dispersal abilities

Cinquante ans après la découverte. État des connaissances et apport des fouilles récentes sur le site campaniforme de la République à Talmont-Saint-Hilaire (Vendée)

International audienceThe Republic site is located on the edge of a small coastal cliff at Talmont-Saint-Hilaire in Vendée (France). It is part of an extensive Bell Beaker settlement along the Vendée coast comprising of almost fifteen sites or possible sites over several kilometers. After the discovery of the Republic site in 1968 by Roger Joussaume, several archaeolog-ical excavations have been conducted between 1988 and 2015 (Bertrand Poissonnier in 1988, Jean-Maurice Gilbert in 1990, Henri Gandois and Lolita Rousseau in 2014 and 2015). Due to its geographical location, archaeological remains appear regularly on the surface or in cliff sections because of erosion. This paper is an overview of discoveries made in the last 50 years relating to this Bell Beaker settlement area (dated from the end of the late Neolithic to the beginning of the Early Bronze Age), which is characterized by a significant pottery corpus. One of the largest of north-west France, it comprises of 2044 sherds and 13.5 kilograms, at least 140 vessels. This includes 59 Bell Beaker vessels decorated with shell and comb printing, 35 cordoned vessels, two bowls and one spoon. 2 582 lithic artifacts made from small coastal pebbles and vein quartz using bipolar flaking as well as ground stone tools attest to knapping and domestic activities with several small knapping areas being identified. The site also shows some evidence of early copper metalworking including metallic slags and two possible features (although these could also have been features relating to salt production) during the early surveys and excavations. The latest archaeological excavation has shown that the metalworking took place on the site using a previously undoc-umented technique for the Atlantic façade, namely the smelting of ore in a furnace-vessel. Recent excavations have also provided the opportunity to make a comprehensive study of all of the artifacts, including those that have remained unpublished and to carry out use wear analysis on chipped stone tools, radiocarbon dating and analyses on cuprous elements and organic residues. The site located on the coast could be a short term and extensive domestic occupation. The geographical situation favors specialized activities such as metalworking and a possible salt production and/or subsistence on foreshore with access to lithic (pebbles, etc.), and fishing resources (shells, fish, etc.), as well as to a navigable network that has undoubtedly fostered trade. It is noteworthy that the few Bell Beaker sites with attested metalworking are located in coastal areas, with the hypothesis that copper ores originated from the Iberian Peninsula. These sites would also have been settlements as metalworking was generally carried out within a domestic context. At Republic, the main domestic area seems to lie outside of the perimeter of the various excavations, unless it has simply disappeared due to coastal erosion, the cliff face having retreated more than 8 meters in the last 30 years. The ongoing documentation of these sites by regular surveying and rescue excavations within the context of coastal erosion, will contribute to a better understanding of the many sites on the Atlantic coast.Le site de la République est localisé en bordure de microfalaise à Talmont-Saint-Hilaire en Vendée (France). Il s’intègre au sein d’un vaste réseau d’occupations campaniformes observable tout le long du littoral vendéen, où près d’une quinzaine de sites sont attestés. Il a été découvert en 1968 par R. Joussaume suite à des prospections de sur-face et a fait l’objet de plusieurs opérations archéologiques de sauvetage entre 1988 et 2015 (B. Poissonnier en 1988, J.-M. Gilbert en 1990, H. Gandois et L. Rousseau en 2014 et 2015). En effet, il fait face à une érosion marine constante faisant apparaître très régulièrement des vestiges en surface ou en coupe de falaise. Cet article permet de faire le point sur cinquante années de découvertes effectuées sur cette vaste occupation attribuée à la culture campaniforme. Cette dernière se caractérise par un important lot de céramiques (l’un des plus conséquents pour le nord-ouest de la France : vases décorés à la coquille et au peigne et vases à cordons) et de pièces lithiques (débitage par percussion posée sur enclume, outils macrolithiques liés à des activités domestiques et de taille et amas de débitage), mais aussi par des indices d’une métallurgie cuprifère précoce. Cette dernière a été reconnue dès les interventions anciennes par la pré-sence de scories et de deux structures possiblement associées (même si l’hypothèse de structures à sel peut être aussi suggérée). Les dernières fouilles ont permis de montrer que cette activité a été menée in situ par le biais d’une technique inédite pour la façade atlantique, à savoir la réduction du minerai dans un vase-four. Enfin, les fouilles récentes ont été l’occasion d’apporter un nouveau regard sur ce site majeur, d’étudier l’intégralité du mobilier archéologique dont une grande partie était restée jusqu’alors inédite, ainsi que de réaliser de nouvelles analyses scientifiques (tracéologie, datation 14C, analyses des éléments cuivreux et des résidus de cuisson dans les céramiques)

Conclusion générale

Ce chapitre apporte un socle de connaissances robustes et novatrices sur la dynamique hydro-morpho-sédimentaire et la qualité des eaux de l’estuaire de la Gironde, deux aspects étroitement interdépendants. Les développements méthodologiques récents (observations in situ continues, télédétection) et numériques (modélisation) ont permis des progrès notoires depuis 1994, date du 1er Livre Blanc. Toutefois, ce bilan met aussi en avant des manques d’information ou des besoins de mieux documenter o..