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Apprentissage, service civique, stages… Les politiques d’insertion des jeunes, entre promesses d’embauche et faux espoirs
No full textInternational audienceDu stage au service civique, en passant par l’apprentissage, les dispositifs visant à favoriser l’insertion des jeunes se sont multipliés ces dernières décennies. Au-delà de leur diversité, tous reposent sur une politique de l’espoir qui cache des dérogations au droit du travail et d’importantes inégalités
News from the GBAR experiment: Improved positron accumulation in a buffer gas trap with a silicon carbide remoderator
No full textInternational audienceThe aim of the GBAR experiment is to measure the gravitational acceleration of antihydrogen by observing the free fall of ultracold anti-atoms. The experiment is installed at CERN’s Antiproton Decelerator/ELENA facility. Positrons are produced by a low energy (9 MeV) linear electron accelerator and captured in a modified Surko (buffer gas) trap. We have recently implemented a silicon carbide-based trapping scheme that replaces the routinely used nitrogen gas with a high quality silicon carbide single crystal in the first phase of the trap. The new setup has been providing stable and efficient positron trapping for more than a year. After a short accumulation in the buffer gas trap, the particles are transported to a high-field (5 T) Penning-Malmberg trap, where a high number of pulses can be collected in a deep potential well. We discuss the performance of the improved positron line and the present status of the experiment
Vers une méthodologie de gestion des risques adaptée au contexte de l’approvisionnement en métaux
No full textFNEGE 2International audienceThis article proposes a methodology for managing risks associated with the supply of metals. It is based on contributions from the field of supply chain risk management (SCRM) and work on the criticality of materials. The aim is to consider the specific characteristics of these supply chains: loss of visibility, complexity, and multiplicity of resources used, as well as the constraints linked to the specific characteristics of metals. In response to these challenges, a five-stage methodology was developed: (1) defining the scope of the analysis, (2) mapping the visible and non-visible parts of the supply chain, (3) estimating and assessing the risks on the basis of indicators taken from the literature, (4) interpreting the results according to a horizontal, vertical and resource-related analysis, and (5) selecting risk management strategies. The contributions of this research are both theoretical and managerial. In theoretical terms, it integrates the concept of criticality into the field of SCRM and proposes a new categorisation of risks adapted to the context of metal-dependent industries. In managerial terms, it proposes an operational methodology with tools for mapping the non-visible part, indicators for risk assessment, and an analytical approach to guide decision-making. However, this research has limitations linked to the dynamic nature of the supply chain, which can make mappings rapidly obsolete, and to data availability.Cet article propose une méthodologie dédiée à la gestion des risques liés à l’approvisionnement en métaux. Elle s’appuie sur les apports du domaine du supply chain risk management (SCRM) et les travaux relatifs à la criticité des matières. L’objectif est de prendre en compte les spécificités de ces chaînes d’approvisionnement : perte de visibilité, complexité, multiplicité des ressources utilisées, ainsi que les contraintes liées aux caractéristiques des métaux. La réponse à ces défis a permis de construire une méthodologie composée de cinq étapes : (1) la définition d’un périmètre d’analyse, (2) la construction d’une cartographie de la chaîne d’approvisionnement pour la partie visible et non visible, (3) l’estimation et l’évaluation des risques à partir d’indicateurs issus de la littérature, (4) l’interprétation des résultats selon une analyse horizontale, verticale et liée à la ressource, et (5) le choix des stratégies de traitement des risques. Les apports de cette recherche sont à la fois théoriques et managériaux. Sur le plan théorique, elle intègre le concept de criticité dans le domaine du SCRM et propose une nouvelle catégorisation des risques adaptée au contexte des industries qui dépendent des métaux. Sur le plan managérial, elle propose une méthodologie opérationnelle accompagnée d’outils pour la cartographie de la partie non visible, d’indicateurs pour l’évaluation des risques, et d’une approche d’analyse pour guider la prise de décisions. Toutefois, cette recherche comporte des limites liées au caractère dynamique de la chaîne d’approvisionnement, qui peut rendre les cartographies rapidement obsolètes, ainsi qu’à la disponibilité des données
Architecture-based comparison of hydraulic power units in quadrupeds, hexapods, and monopods: A systematic review
No full textInternational audienceRobots have increasingly become integral in enhancing human life, with growing demands for robots with high payload-to-weight ratios and dynamic capabilities like running and jumping. Hydraulic actuation, renowned for its high power-to-weight ratio, is a critical enabler of these capabilities. However, its effectiveness depends significantly on the specific architecture employed. This review systematically examines centralized hydraulic power units (cHPUs) and electro-hydraulic actuators (EHAs) in legged robots, specifically quadrupeds, hexapods, and monopods, focusing on power density, weight, joint power distribution, and application suitability. Following PRISMA guidelines, we analyzed over 35 hydraulic-legged robots from 70+ articles, finding that while cHPUs offer greater power, their efficiency is reduced by the weight and leakage of components like valves and hoses. In contrast, EHAs demonstrated a superior power-to-weight ratio due to their self-contained, hoseless design. Our analysis suggests that cHPUs are better suited for a few closely positioned joints, while EHAs for powering multiple joints over larger distances. Based on empirical data from manufactured robots, this research highlights EHAs’ advantages in power density optimization. It recommends future studies explore additional metrics like power-to-volume ratios and cost-effectiveness to refine hydraulic architecture selection for robotic systems
Les métiers de la conception urbaine à la conquête de nouveaux territoires professionnels
No full textInternational audienc
Ad valorem taxation in a multiproduct monopoly
No full textFNEGE 1, ABS 4International audienceWe study the pass‐through of ad valorem taxes with a multiproduct monopolist. We characterize two mechanisms whereby an ad valorem tax on one good reduces all prices (Edgeworth's paradox), depending on the goods being substitutes or complements. We also find that the tax can increase the supply of all goods. Hence, consumer surplus and welfare can increase even when the goods are underprovided compared to the social optimum. We provide several applications where these results hold. Our findings indicate that in a multiproduct setting the effects of unit and ad valorem taxes on market outcomes and welfare are fundamentally different
Optimisation of mesenchymal stromal cells conditioning in perspective of a treatment for Myasthenia gravis
No full textInternational audienceINTRODUCTION: Conventional treatments of MG by immunosuppressants cause severe side effects, therefore cell-based approaches represent innovative therapeutic tools. Adipose-derived Mesenchymal Stem Cells (MSC) are multipotent progenitors capable of modulating the activity of the immune system through soluble mediators, extracellular vesicles (EV), and direct cell-to-cell contact. Their effectiveness is increased by conditioning by co-culture with circulating mononuclear cells (PBMC) or by treatment with cytokines. Previously, molecular, phenotypic and functional characterizations of conditioned MSC (cMSC) provided activation signatures, and secretome analysis suggested a list of 30 candidate molecules responsible for conditioning.OBJECTIVE: We identify a combination of molecules that could substitute to the co-culture with PBMC for conditioning. In parallel, we evaluate an acellular therapy using EVs secreted by cMSC. Then, we compare the efficacies of resting MSC, of MSC activated by the combination of active molecules, and of the EV they produce. Our final goal will be to translate these observations into our humanized animal model of MG.METHODS: The most active molecules and combinations are identified through phenotypic changes (flow cytometry). EV produced by MSC are collected by ultracentrifugation and analysed by NTA. The efficacies of cells and EV are assessed in vitro, testing the inhibition of proliferation of PBMC from healthy and MG patients (CFSE assay), and the phenotypic modulation of mononuclear immune cells (flow cytometry). RESULTS: Among the candidates, the pro-inflamatory cytokines TNFα, IFNγ, and IL-1β modified the expression of readout markers (CD26, CD54) in MSC cultures when used alone, or differentially when used in combinations. We optimize and downsize the culture conditions to set a medium-throughput screening based on readout markers modulations. SUMMARY/CONCLUSION: Our work unveils treatment-dependent markers of MSC conditioning. Upon transfer to clinically usable procedures, cellular or acellular products may have therapeutic applications in the context of MG and other autoimmune diseases
DNA aggregation and resolubilization in the presence of polyamines probed at the single molecule level using nanopores
No full textInternational audienceThe compaction and decompaction of double-stranded DNA play a crucial role in regulating gene expression. We use solid-state nanopores to study, at the single-molecule level, the translocation of DNA chains in relation to the macroscopic phase transition induced by polyamines. To prevent nonspecific interactions between the nanopore surface and DNA, nanopores were passivated, and experiments were performed in high salt conditions. We first determine the translocation dynamics of DNA. The event frequency varies exponentially with the applied voltage and linearly with the polyelectrolyte concentration. The translocation time decreases exponentially with applied voltage. Addition of polyamine to a DNA solution leads to DNA aggregation and subsequent phase separation; a macroscopic DNA-rich and dense phase coexists with a poor-DNA (diluted) phase. We pipetted part of the diluted phase and studied chain translocation. We observe a progressively decreasing event frequency of DNA in the solution at the nanopore entry as a function of polyamine concentration, approaching zero Hertz. At this point, no DNA remained in the poor phase, and all the DNA was found in the precipitated rich phase. If we increase the polyamine concentration even further, the event frequency increases progressively until it reaches a plateau value due to the solubilization of DNA aggregates. At high salt concentrations in NaCl, we observe that the event frequency of DNA in solution remains constant as a function of polyamine concentrations. We compare DNA phase transitions using nanopore and UV bulk experiments, and we find the same charge-to-molar ratio for DNA precipitation and solubilization. We interpret these results through polyelectrolyte behavior
Replication-independent eviction of H2B.8 reveals chromatin reprogramming during seed imbibition
No full textThe transition from seed to seedling involves major changes in nuclear organization and gene expression, yet the extent to which this developmental transition requires chromatin reprogramming remains largely unexplored. Here, we report that Arabidopsis dry seed embryos accumulate the histone variant H2B.8, which contributes to higher-order chromatin organization by forming spatial clusters that structure the 3D nuclear space. H2B.8 forms heterotypic nucleosomes at euchromatic transposons and lowly expressed genes and, during imbibition, modulates the transcriptional activation of a subset of these genes. Imbibition triggers a decrease in H2B.8 transcripts and the eviction of H2B.8 proteins in a process that operates independently of DNA replication but requires protein translation and de novo transcription. Histone eviction is not limited to H2B.8 as imbibition also induces the turnover of the H3.3 histone variant, thereby initiating a broad, replication-independent chromatin reprogramming process. These findings highlight a fundamental mechanism of epigenetic regulation during early plant development.</div
Accurate online action and gesture recognition system using detectors and Deep SPD Siamese Networks
No full textInternational audienceOnline continuous motion recognition is a hot topic of research since it is more practical in real life application cases. Recently, Skeleton-based approaches have become increasingly popular, demonstrating the power of using such 3D temporal data. However, most of these works have focused on segment-based recognition and are not suitable for the online scenarios. In this paper, we propose an online recognition system for skeleton sequence streaming composed from two main components: a detector and a classifier, which use a Semi-Positive Definite (SPD) matrix representation and a Siamese network. The powerful statistical representations for the skeletal data given by the SPD matrices and the learning of their semantic similarity by the Siamese network enable the detector to predict time intervals of the motions throughout an unsegmented sequence. In addition, they ensure the classifier capability to recognize the motion in each predicted interval. The proposed detector is flexible and able to identify the kinetic state continuously. We conduct extensive experiments on both hand gesture and body action recognition benchmarks to prove the accuracy of our online recognition system which in most cases outperforms state-of-the-art performances