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A Microfluidic Platform for Actin‐Based Membrane Remodeling Reveals the Stabilizing Role of Branched Actin Networks on Lipid Microdomains
No full textInternational audienceCell shape changes, essential for processes such as motility or division, are controlled by the actomyosin cortex that actively remodels biological membranes. Their mechanisms can be deciphered in vitro using biomimetic reconstituted systems, such as giant unilamellar vesicles (GUVs) with controlled lipid composition coupled to reconstituted actin networks. These assays allow mimicking cell shape changes in controlled biochemical and biophysical environments. However, studying the dynamics of these shape changes on statistically significant populations of GUVs with the possibility to sequentially modify the protein composition of the assay is a major experimental challenge. To address these issues, a microfluidic approach is used to immobilize several dozens of isolated GUVs and monitor membrane and actin network evolution. The loading of the chamber with GUVs and actin is first characterized. Then, the actin‐induced remodeling of populations of homogeneous and phase‐separated GUVs is monitored and shows that actin networks prevent the coalescence of lipid microdomains and that, in return, the number of domains affects the actin network structure. This microfluidic‐based experimental strategy, thus, allows for studying actin‐induced membrane deformation in vitro and can be adapted to other studies on membrane remodeling processes
Transports et mobilités : autonomisation ou pleine affiliation à l’histoire des sciences et des techniques ?
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Deviation from Power-Law Distribution when Scaling the Distribution of Marine Plankton Folds from Genomes to Communities
No full textAt different scales of living systems, biological entities appear to follow scaling laws, such as power laws, which are often explained from stochastic mechanisms. This is the case for the number of species in a community and the number of genes or protein folds in a genome. Resulting from evolutionary processes combining gene family duplications and expansions with selective pressures, the distribution of protein folds systematically follows a power law in all individually observed genomes. A small number of folds are highly prevalent, while the majority of folds appear only once per genome. However, previous studies on fold occurrence have focused on individual genomes, isolated from their community contexts. In the oceans, plankton communities consist of complex assemblages of species, each exhibiting variable relative abundances. We investigated the consequences of this variability on the composition and distribution of folds by considering the relative abundance of species. By annotating folds to genes of environmental genomes of plankton collected by the Tara Oceans expedition, we show that the relative abundance of folds deviates from the classical power law and instead follows a Type II Pareto distribution. This model, typically observed in other complex organizations such as economics, allows us to classify different categories of folds that exhibit biogeographical differences. Our results show that scaling fold distributions from individual genomes to species communities lead to a deviation from the expected behavior of simple power-law relationship towards a more complex model. This phenomenon could be linked with the variable complexity of marine planktonic ecosystems
Distributed event-triggered fault estimation for Takagi–Sugeno multi-agent systems with unmeasurable decision variables
No full textInternational audienceThis paper proposes a novel distributed fault estimation framework for a class of nonlinear multi-agent systems (MASs), addressing time-varying multiplicative and additive faults in both actuators and sensors. To address these challenges, the Takagi–Sugeno (T-S) system model is employed, incorporating unmeasurable decision variables, which introduces more complexity compared to known decision variables. This study pioneers the one-sided Lipschitz approach in this context, offering significant advancements over the traditional Lipschitz method. A two-step design process is presented to estimate system states, faults, and external disturbances through an th-order proportional-integral observer and a constrained least squares estimator, which is data-driven. Agents can update their observers by using relative residual outputs derived from neighboring information, enhancing both fault and state estimation accuracy. Furthermore, a dynamic event-triggered communication protocol enables efficient output sharing and reduces communication costs. The observer design conditions are formulated as an optimization problem constrained by linear matrix inequalities, ensuring robust H-infinity performance. Simulation results validate the effectiveness of the proposed method for robust fault estimation in nonlinear MASs
SINEUP RNA rescues molecular phenotypes associated with CHD8 suppression in autism spectrum disorder model systems
No full textInternational audienceLoss-of-function mutations in the chromodomain helicase DNA-binding 8 (CHD8) gene are strongly associated with autism spectrum disorders (ASDs). Indeed, the reduction of CHD8 causes transcriptional, epigenetic, and cellular phenotypic changes correlated to disease, which can be monitored in assessing new therapeutic approaches. SINEUPs are a functional class of natural and synthetic antisense long non-coding RNAs able to stimulate the translation of sense target mRNA, with no effect on transcription. Here, we employed synthetic SINEUP-CHD8 targeting the first and third AUG of the CHD8 coding sequence to efficiently stimulate endogenous CHD8 protein production. SINEUP-CHD8 were effective in cells with reduced levels of the target protein and in patientderived fibroblasts with CHD8 mutations. Functionally, SINEUP-CHD8 were able to revert molecular phenotypes associated with CHD8 suppression, i.e., genome-wide transcriptional dysregulation, and the reduction of H3K36me3 levels. Strikingly, in chd8-morpholino-treated and ENU mutant zebrafish embryos, SINEUP-chd8 injection confirmed the ability of SINEUP RNA to rescue the chd8-suppression-induced macrocephaly phenotype and neuronal hyperproliferation. Thus, SINEUP-CHD8 molecule(s) represent a proof-of-concept toward the development of an RNA-based therapy for neurodevelopmental syndromes with implications for, and beyond ASD, and relevant to genetic disorders caused by protein haploinsufficiency
Human-like Dexterous Grasping Through Reinforcement Learning and Multimodal Perception
No full textInternational audienceDexterous robotic grasping with multifingered hands remains a critical challenge in non-visual environments, where diverse object geometries and material properties demand adaptive force modulation and tactile-aware manipulation. To address this, we propose the Reinforcement Learning-Based Multimodal Perception (RLMP) framework, which integrates human-like grasping intuition through operator-worn gloves with tactile-guided reinforcement learning. The framework’s key innovation lies in its Tactile-Driven DCNN architecture—a lightweight convolutional network achieving 98.5% object recognition accuracy using spatiotemporal pressure patterns—coupled with an RL policy refinement mechanism that dynamically correlates finger kinematics with real-time tactile feedback. Experimental results demonstrate reliable grasping performance across deformable and rigid objects while maintaining force precision critical for fragile targets. By bridging human teleoperation with autonomous tactile adaptation, RLMP eliminates dependency on visual input and predefined object models, establishing a new paradigm for robotic dexterity in occlusion-rich scenarios
A hybrid constraint programming and cross-entropy approach for balancing U-Shaped disassembly line with flexible workstations and spatial constraints
No full textInternational audienceDisassembly lines are an effective means for the large-scale, industrialized recycling of end-of-life products. Among these, U-shaped disassembly lines are particularly noted for their combination of flexibility and production efficiency. This study addresses the U-shaped disassembly line balancing problem, considering the coexistence of separate stations and spatial limitations within workstations. A mixed-integer nonlinear programming model and a constraint programming model are developed to accurately capture this complex problem. Additionally, a novel hybrid constraint programming with a goal-driven cross-entropy optimization algorithm (CP–GDCE) is introduced. This algorithm combines a multi-objective cross-entropy grouping framework, a constraint programming-based heuristic initialization, a multi-point crossover recombination mechanism, and large neighborhood search techniques, significantly enhancing solution efficiency and accuracy. Extensive benchmarking and experimental validation indicate that the CP–GDCE not only excels in addressing the specific problem of this study but also demonstrates superiority in classic disassembly line balancing issues. In 21 test cases, the CP–GDCE achieved superior hypervolume and inverted generational distance values compared to 11 benchmark algorithms. A practical application using a printer disassembly example shows that the proposed U-shaped configuration is highly flexible and efficient, compatible with both traditional U-shaped and straight disassembly lines. This configuration significantly reduces the total length of the disassembly line, improving space utilization and highlighting its practical potential and advantages
Inventories dynamics and sectoral propagation mechanisms an empirical study with French and American data
No full textThe aim of this paper is to reveal empirically two kinds of mechanisms which operate on inventories: one is demand related and the other is supply related. Accordingly, we first test the presence of cointegration relationships in the dynamic bivariate inventories-sales model then we perform Granger-causality tests. It allows for a full specification of the dynamic properties of these series. Our results suggest that inventories movements stem from demand factors. Moreover, inventories and sales are linked in the long run, especially in the trade sectors. In France the dataset used prevents us from concluding in this way.Cet article se propose d'étudier empiriquement l'existence de deux types de mécanismes inhérents aux stocks, l'un dépendant de la demande et l'autre de l'offre. Dans cette perspective, nous testons d'abord la présence de relations de cointégration dans le modèle bivarié stocks-ventes, ensuite nous appliquons les tests de causalité au sens de Granger. Cette démarche permet de spécifier complètement les propriétés dynamiques de ces variables
Open innovation within the hospital: lessons from an additive manufacturing initiative
No full textFNEGE 2, ABS 1International audienceNew paradigms in healthcare offer hospitals the opportunity to play a greater role in innovation and to explore the potential offered by open innovation (OI). This article investigates how, and under what conditions, OI could enhance the innovation performance of hospitals. We analyze the case of Greater Paris University Hospitals and their unique experiment involving a large in-house 3D printing platform operated in collaboration with a specialist services provider. Our study reveals that on-site OI can lead to significant product, managerial, and process innovations for hospitals. However, our study also suggests that such OI initiatives will not fully succeed unless hospitals can capture a share of the value they create. This, in turn, requires the capability to maximise dissemination across the organization and to reach internal consensus on how value will be captured from the OI initiative
Assemblages supramoleculaires de type (pseudo)polyrotaxane : vers la synthèse de modèles biocompatibles de cellules musculaires
No full textInspired by the living world, biomimicry encourages the development of new families of materials for a wide range of applications. In this context, (pseudo)polyrotaxane-type supramolecular assemblies, like strings of pearls, could make it possible to obtain innovative stimulable materials, for example materials capable of mimicking the movement of a muscle under the effect of a stimulus. The aim of this thesis was to synthesize biocompatible, thermostimulable (pseudo)polyrotaxanes from γ-cyclodextrin (γ-CD) and block copolymers, consisting of poly(N-isopropylacrylamide) (PNIPAM) and poly(ethylene oxide) (POE), in order to obtain materials whose mechanical properties could be reversibly modified in response to an external stimulus. PNIPAM was chosen for its thermosensitive properties, while POE was chosen for its particular affinity with cyclodextrins, making them easier to thread. During this thesis work, the formation of supramolecular assemblies with CDs was first studied in the presence of homopolymers of PNIPAM and POE (of variable lengths and variable ends), then with diblock, then triblock copolymers (ABA or BAB), synthesized by different routes (coupling, ATRP, RAFT). Characterization of the edifices was carried out by mobilizing various analytical techniques: 1H NMR, MALDI-TOF, DRX, CES and TGA. The results showed that γ-CDs threaded predominantly onto the POE block whether located in the center or at the ends of the various copolymers with a number of CDs that could be controlled, depending on the (γ-CDs):(polymer) stoichiometry adopted prior to complexation, chain length, temperature. Several architectures have been proposed for these assemblies.En s'inspirant du vivant, le biomimétisme invite à développer de nouvelles familles de matériaux, pour des applications variées. Dans ce contexte, des assemblages supramoléculaires de type (pseudo)polyrotaxanes, semblables à des colliers de perles, pourraient permettre d'obtenir des matériaux innovants stimulables, par exemple des matériaux capables de mimer le mouvement d'un muscle sous l'effet d'un stimulus. L'objectif de cette thèse a été de synthétiser des (pseudo)polyrotaxanes biocompatibles et thermostimulables, à partir de γ-cyclodextrine (γ-CD) et de copolymères à blocs, constitués de poly(N-isopropylacrylamide) (PNIPAM) et de poly(oxyde d'éthylène) (POE), afin d'obtenir des matériaux dont les propriétés mécaniques pourraient être modifiées de manière réversible en réponse à un stimulus extérieur. Le PNIPAM a été choisi pour son caractère thermosensible, tandis que le POE, a lui été choisi pour son affinité particulière avec les cyclodextrines, facilitant ainsi leur enfilage. Au cours de ces travaux de thèse, la formation d'assemblages supramoléculaires avec des CDs a d'abord été étudiée en présence d'homopolymères de PNIPAM et de POE (de longueurs variables et d'extrémités variables), puis avec des copolymères diblocs, puis triblocs (ABA ou BAB), synthétisés selon différentes voies (couplage, ATRP, RAFT). La caractérisation des édifices a été réalisée en mobilisant diverses techniques d'analyse : RMN 1H, MALDI-TOF, DRX, CES et TGA. Les résultats ont montré que les γ-CDs s'enfilaient majoritairement sur le bloc de POE qu'il soit situé au centre ou aux extrémités des différents copolymères avec un nombre de CDs que l'on peut contrôler, en fonction de la stœchiométrie (γ-CDs) : (polymère) adoptée avant la complexation, la longueur des chaines, la température. Plusieurs architectures ont été proposées pour ces assemblages