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Parameter identification for a reduced transport model in fusion plasma
No full textInternational audienceTwo-dimensional transport codes for the simulation of tokamak plasmas are simplified versions of full 3D fluid models, where plasma turbulence is averaged out. One of the main challenges in such reduced models is to accurately reconstruct transverse transport fluxes that arise from the averaging of stresses due to fluctuations. These transverse fluxes are typically approximated by ad-hoc diffusion coefficients (turbulent eddy viscosity) manually adjusted to align numerical solutions with experimental observations. They can vary significantly depending on the type of tokamak, the experimental conditions, and even the location within the device, severely limiting the predictive capability of these codes for new configurations. To address this issue, we recently proposed an innovative approach to fusion plasma simulations by introducing two additional transport equations for turbulence-related variables (specifically, the turbulent kinetic energy κ and its dissipation rate ε) into the mean-flow system to estimate the turbulent eddy viscosity. This approach also introduces new free parameters, but they are primarily governed by the underlying transport physics and thus exhibit considerably less variation across devices and plasma regions. In this paper, we continue an ongoing study of data assimilation techniques to determine the free parameters of the κε model for transverse turbulent plasma transport. Based on digital twin experiments within the framework of equations averaged over the magnetic surfaces of the tokamak, we provide an in-depth study of optimization strategies to improve the performances of the calibration algorithm in a complex configuration with considerable scale variation of the parameters
New analytical approaches to sickle blade use and cereal harvesting at Ras Shamra-Ugarit during the Late Bronze Age
No full textInternational audienceAt Ras Shamra-Ugarit, knapped stone tools largely persisted during the Late Bronze Age, despite the widespread use of metal. Flint was used to produce geometric sickle elements and tools as part of the domestic toolkit. Previous technological and functional studies of the lithic material from the “Centre de la Ville” and “Grand-rue” areas revealed the inhabitants’ involvement in agricultural activities, particularly cereal harvesting and sickle maintenance. In this study, we apply recent analytical methods – confocal microscopy for gloss texture analysis and FT-IR spectroscopy for the identification of hafting residue – to reassess the function of these tools. Our results support earlier interpretations that these flint implements were used for cereal harvesting, underlining their importance in food production. More specifically, in this study, we demonstrate that sickles were used for low-cut harvesting of fully ripened domesticated cereals, pointing to a mature and well-developed farming system. This paper represents an original contribution to applying non-destructive and interdisciplinary qualitative and quantitative methods for investigating lithic tools use at a site where metalworking practices were fully established.À Ras Shamra-Ougarit, les outils en pierre taillée ont largement perduré durant l’âge du Bronze récent, malgré l’usage généralisé du métal. Le silex servait à produire des éléments géométriques de faucilles ainsi que d’autres outils faisant partie de l’équipement domestique. Des études technologiques et fonctionnelles antérieures sur le matériel lithique provenant des secteurs du « Centre de la Ville » et de la « Grand-rue » ont révélé l’implication des habitants dans des activités agricoles, en particulier la récolte des céréales et l’entretien des faucilles. Dans cette étude, nous appliquons des méthodes analytiques récentes – la microscopie confocale pour l’analyse de la texture du lustre et la spectroscopie IR-TF pour identifier les résidus liés à l’emmanchement – afin de réévaluer la fonction de ces outils. Nos résultats confirment les interprétations précédentes selon lesquelles ces outils en silex ont servi à la récolte des céréales, soulignant leur rôle dans la production alimentaire. Plus précisément, cette étude montre que les faucilles servaient à couper, au ras du sol, des céréales domestiquées arrivées à pleine maturité, ce qui témoigne d’un système agricole développé et bien établi. Cet article constitue une contribution originale à l’application de méthodes interdisciplinaires, qualitatives et quantitatives, non destructives, pour étudier la fonction des outils lithiques sur un site où les pratiques métallurgiques étaient pleinement établies
Fluid processes highlighted by temporal variations of ‐value during swarms and aftershocks sequences in the Ubaye Region (Western Alps, France)
No full textInternational audienceThe b ‐value from the Gutenberg‐Richter law is a crucial parameter in the assessment of seismic hazard. Its temporal variations may also bring useful insights on the processes driving seismicity at depth, even if not yet fully understood. In this paper, we focus on the temporal evolution of the b ‐value in the Ubaye Region (French Western Alps) which was hit by seismic swarms (2003–2004) and complex sequences with several mainshocks (2012–2015). The swarm‐like sequences show a common temporal behavior of b ‐value characterized by an increase and then a return to the initial level. The temporal b ‐value pattern for the mainshock‐aftershock‐like sequences is quite different. After a drop in the b ‐value that may follow the mainshock, the b ‐value increases above the background level before going back to it. Moreover, no precursory pattern can be identified before the mainshock. Fluid processes are recognized to play a crucial role in the driving mechanisms of these seismic sequences. Drawing parallel between swarms and aftershock sequences suggests that the b ‐value depicts fluid‐processes in the Ubaye Region seismicity. We propose that b ‐value shows a complex behavior, with variations due to Coulomb stress‐transfer from the mainshock and fluid‐pressure processes. Therefore, even with a catalog made at the French national scale, the b ‐value variations may help to monitor the on‐going processes at depth
Étude du fragment C99 dans la maladie d'Alzheimer : dimérisation, trafic intracellulaire et toxicité
No full textAlzheimer's disease (AD) is a neurodegenerative disorder characterized by abnormal protein accumulation and widespread cellular dysfunctions, ultimately leading to progressive cognitive decline. Among the fragments generated by the proteolytic processing of the amyloid precursor protein (APP), the C99 fragment has emerged as a key contributor to early neuronal alterations, independently of amyloid β (Aβ). However, the specific role of C99 dimers remains poorly understood, primarily due to the absence of reliable tools to discriminate effectively between monomeric and dimeric forms of C99.In this context, my work was structured around two main objectives. First, I developed a novel tool based on the bimolecular fluorescence complementation (BiFC) technique, allowing the precise spatial and temporal visualization of de novo C99 dimer formation in HeLa cells. Using this approach, I demonstrated that C99 dimerization is initiated primarily within the trans-Golgi network (TGN), where dimers accumulate. Second, the results revealed the functional consequences of this accumulation on cellular homeostasis: C99 dimers induce fragmentation of the TGN and are sequestered into perinuclear aggresomes, markers of proteotoxic stress associated with impaired proteasomal function. Furthermore, γ-secretase inhibition redirects monomeric C99 to the endosomal-lysosomal-autophagic (ELA) system, where dimerization upon accumulation also occurs, ultimately impairing autophagic degradation.In conclusion, the tool developed in this project uncovered previously unrecognized pathological aspects of C99. Its dimerization emerges as a pivotal event, competing with γ-secretase cleavage and affecting C99's intracellular fate. This process not only determines C99 trafficking within subcellular compartments but also contributes to cellular dysfunctions, notably by disrupting proteasome activity and Golgi integrity. These findings offer new insights into early pathological mechanisms in Alzheimer's disease.La maladie d'Alzheimer (MA) est une maladie neurodégénérative caractérisée par l'accumulation anormale de protéines et des dysfonctionnements cellulaires conduisant à une perte progressive des fonctions cognitives. Parmi les fragments issus du clivage de la protéine précurseur de l'amyloïde (APP), le fragment C99 suscite un intérêt croissant en tant qu'acteur clé des altérations précoces de la cellule neuronale, indépendamment de l'amyloïde β (Aβ). Toutefois, le rôle spécifique des formes dimériques de C99 reste largement inexploré, en raison de l'absence d'outils permettant de discriminer efficacement les états monomérique et dimérique de ce fragment.Dans ce contexte, mon travail s'est articulé autour de deux axes principaux. D'une part, j'ai développé un nouvel outil reposant sur la technique de complémentation bimoléculaire de fluorescence (BiFC), permettant de visualiser avec précision spatiale et temporelle la formation de novo des dimères de C99 dans des cellules HeLa. Grâce à cet outil, mes travaux ont mis en évidence que la dimérisation de C99 s'initie principalement dans le réseau trans-Golgi (TGN), où les dimères s'accumulent. D'autre part, les résultats montrent les conséquences de cette accumulation sur l'homéostasie cellulaire : les dimères induisent une fragmentation du TGN et sont séquestrés dans des agrésomes périnucléaires, marqueurs d'un stress protéotoxique lié à une altération de la fonction protéasomale. Par ailleurs, l'inhibition de la γ-sécrétase conduit à un adressage des monomères C99 vers le système endosomal-lysosomal-autophagique (EAL), où ils peuvent également former des dimères sous l'effet de leur accumulation, entraînant un défaut de la dégradation autophagique.En conclusion, l'outil développé au cours de ce projet a permis de révéler des aspects pathologiques de C99 jusqu'alors inexplorés. La dimérisation de C99 apparaît comme un événement déterminant, entrant en compétition avec son clivage par la γ-sécrétase, et influençant de manière déterminante son devenir intracellulaire. Cette dimérisation conditionne non seulement le trafic de C99 au sein des compartiments subcellulaires, mais contribue également aux dysfonctions cellulaires qu'il induit, notamment en perturbant le système protéasomal et l'intégrité de l'appareil de Golgi. Ces résultats ouvrent ainsi de nouvelles perspectives sur les mécanismes précoces impliqués dans la maladie d'Alzheimer
Is a change in mouth opening associated with improvements in quality of life in children with type 1 obstructive sleep apnoea after adenotonsillectomy? Protocol for the JawChild prospective cohort study
No full textInternational audienceIntroduction Adenotonsillectomy is the primary treatment for type 1 obstructive sleep apnoea (OSA1). Although polysomnography (PSG) remains the gold standard for measuring Apnoea-Hypopnoea Index, it is a labour-intensive procedure and does not correlate with improvements in quality of life postadenotonsillectomy. Mouth breathing is associated with poorer quality of life in children. Mandibular movement (MM), which measures mouth opening, is a validated measure of respiratory effort that can be easily and safely assessed in children using the JAWAC technology. This study aims to evaluate the relationship between changes in quality of life and changes in mouth opening in children with OSA1 after undergoing adenotonsillectomy. Secondary objectives include evaluating changes in quality of life, clinical symptoms and other MM and PSG metrics in the same population. Methods and analysis This exploratory, non-randomised, monocentric, prospective cohort study with a non-blinded single arm will include 50 children aged 3–7 years, undergoing adenotonsillectomy at the Clinique Saint Jean, Montpellier, France. Quality of life will be measured using the parent version of the Paediatric Quality of Life Inventory and MM metrics will be measured during PSG using the JAWAC system during the inclusion visit and 3 months after adenotonsillectomy. The primary outcome will be the correlation between the changes in quality of life and mouth opening (1/10 mm) postadenotonsillectomy. Secondary analyses will evaluate changes in clinical symptoms, PSG measures and other MM metrics including respiratory effort, as well as the associations between these measures. Ethics and dissemination This study was approved by an independent ethics committee (Comité de Protection des Personnes Est) on 24 March 2025 (2024-A02761-46) and will be conducted in accordance with French law, good clinical practice and the guidelines of the Declaration of Helsinki. Study findings will be disseminated through international peer-reviewed journal articles as well as public, academic presentations at national and international conferences. Trial registration number NCT06973928
Childhood trauma affects speech and language measures in patients with major depressive disorder during clinical interviews
No full textInternational audienceBackground: Speech analysis has shown significant promise as a potential biomarker for depression. However, no studies to date have examined the impact of childhood trauma on speech and language patterns in individuals with depression. This study aims to explore the relationship between vocal characteristics and depressive symptoms, while also assessing how childhood trauma may shape these patterns. Methods: 27 participants with a major depressive episode were included. The severity of depression was assessed using the Montgomery & Asberg Depression Rating Scale (MADRS) and the Beck Depression Inventory II. Childhood trauma was measured using the Childhood Trauma Questionnaire. Speech recordings from the MADRS semi-structured interview and a free clinical interview were analyzed using speaker diarization, automatic speech recognition, and feature extraction. Results: Several acoustics features were significantly associated with depression severity. Correlation analysis revealed that greater depression severity was linked to shorter, less diverse speech, characterized by fewer words, fewer semantic clusters, and reduced articulatory effort. In contrast, childhood trauma was positively associated with distinct speech characteristics. Higher trauma load was associated with richer, longer, and more syntactically complex speech. Additionally, utterances were shorter, with more frequent shifts between semantic clusters, reflecting a more fragmented speech pattern influenced by traumatic load. Conclusion: Our study highlights the influence of childhood trauma on vocal and linguistic characteristics of patients with depression. Automated language analysis offers the possibility to identify biomarkers of traumatic load in patients with depression. This could improve diagnostic accuracy, guide therapeutic management and monitor clinical progress
A view of Research and Standardisation: the oneM2M IoT standard by ETSI
No full textInternational audienceMy personal view on how research and standardisation in IoT should go hands in hand
Extreme statistics as a probe of the superfluid to Bose-glass Berezinskii-Kosterlitz-Thouless transition
No full textRecent studies of delocalization-localization transitions in disordered quantum chains have highlighted the role of rare, chain-breaking events that favor localization, in particular for high-energy eigenstates related to many-body localization. In this context, we revisit the random-field XXZ spin-1/2 chain at zero temperature with ferromagnetic interactions, equivalent to interacting fermions or hard-core bosons in a random potential with attractive interactions. We argue that localization in this model can be characterized by chain-breaking events, which are probed by the extreme values of simple local observables, such as the on-site density or the local magnetization, that are readily accessible in both experiments and numerical simulations. Adopting a bosonic language, we study the disorder-induced Berezinskii-Kosterlitz-Thouless (BKT) quantum phase transition from superfluid (SF) to Bose glass (BG), and focus on the strong disorder regime where localization is driven by weak links. Based on high-precision density matrix renormalization group simulations, we numerically show that extreme local densities accurately capture the BKT transition, even for relatively short chains ranging from a few dozen to a hundred sites. We also discuss the SF-BG transition in the weak disorder regime, where finite-size effects pose greater challenges. Overall, our work seeks to establish a solid foundation for using extreme statistics of local observables, such as density, to probe delocalization-localization transitions in disordered quantum chains, both in the ground state and at high energy
Approche didactique de l’introduction d’un partenaire industriel dans deux situations d’enseignement-apprentissage du design
No full textInternational audienceThis paper studies the impact of the introduction of the “operational” dimension within the design teaching-learning situations of two groups of students facing the same task proposed by an industrial partner. To understand the joint action identified, a typology of the knowledge at stake in the two didactic situations allows us to characterize the expected outcome of the situations: the development of a design skill through a design experience. The study closely analyzes the students’ activity, which focuses on the operational brief against the didactic contract. The presence of the industrial partner and the “operational” dimension invest the didactic environment, modify students’ representations and experiences, and create an "elsewhere of the didactic".Cette contribution étudie l’incidence de l’introduction de l’ « opérationnel » au sein de situations d’enseignement-apprentissage du design de deux groupes d’étudiants confrontés à la même tâche proposée par un partenaire industriel. Pour comprendre l’action conjointe identifiée, une typologie des savoirs en jeu dans les deux situations didactiques permet de caractériser l’attendu des dispositifs : le développement d’une compétence de conception par une expérience de design. L’étude s’appuie sur l’analyse clinique de l’activité d’étudiants qui se focalisent sur une même commande opérationnelle au sein de deux situations distinctes. Le partenaire industriel et l’opérationnel investissent le milieu didactique, modifient les représentations et les expériences qu’en ont les étudiants et créent un « ailleurs du didactique »
The metal-poor tail of the APOGEE survey
No full textInternational audienceContext. The most metal-poor stars in our Galaxy contain important clues of its earliest history, particularly those occupying the inner regions of the Galaxy. In the search for such metal-poor stars, large spectroscopic surveys are an invaluable tool. However, the spectra of metal-poor stars can be difficult to analyse because of the relative lack of available lines, which can also lead to misclassification. Aims. We aim to identify the stars observed by the APOGEE survey that are below the metallicity limit of APOGEE's analysis. For the highest confidence candidates, we classify the orbital properties of the stars to investigate whether their orbital distribution matches what we would expect for stars that are this metal poor and to select especially interesting targets for spectroscopic follow-up purposes. Methods. We examined the properties derived by APOGEE for metal-poor stars from the literature to find signatures of stars with a metallicity below the range of the grid used for spectral analysis. Once identified within APOGEE, we computed the orbits of our metal-poor candidates using AGAMA.Results. The calibrated APOGEE stellar parameters provide a clear signature of the most metal-poor stars in the survey, indicated by null values for their metallicities while having effective temperatures and surface gravities determined by the pipeline. From comparison with the literature, we find that, within a temperature range of 3700-6700 K and above a threshold of S/N > 30, the vast majority of APOGEE stars without calibrated metallicities are very metal poor. Additional cleaning by visual inspection of the spectra improved the purity of the sample further. The radial velocities provided by APOGEE, Gaia DR3 positions and astrometry along with spectrophotometric distances derived in this work allowed for the computation of their orbits. In this work, we carefully selected 289 very metal-poor red giant stars (likely below [Fe/H] = -2.5) from the APOGEE results. Our sample contains 16 very metal-poor member candidates of the Magellanic Clouds, 14 very metal-poor stars with orbits confined to the inner Galaxy, and 13 inner Galaxy halo interlopers. These samples significantly add to the very metal-poor stars known in these regions and allow for a more detailed picture of early chemical evolution across different environments.</div