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Évaluation des propriétés anti-inflammatoires de molécules naturelles biosourcées et de synthèse bio-inspirées
No full textChronic inflammatory diseases represent a major health concern, with their incidence steadily increasing. Unfortunately, current therapies remain insufficient to offer hope for disease remission. The search for new anti-inflammatory molecules, combined with a deeper understanding of inflammatory mechanisms—such as extracellular matrix remodeling—will help identify new and relevant therapeutic targets. The objectives of my thesis were to establish a macrophage-based model and evaluate the anti-inflammatory properties of natural (oligosaccharide) and bio-inspired (semi-synthetic and synthetic) molecules. The effects of these molecules were confirmed by measuring the production of inflammatory markers such as IL-6 and TNF-α, assessing the activation of inflammatory signaling pathways (ERK, JNK, p38, and Akt), and using in vivo mouse models. Notably, we highlighted the anti-inflammatory properties of pharmaco-modulated flavones and their mechanism of action in the treatment of chronic pain, as well as oligosaccharides derived from λ-carrageenan for the treatment of psoriasis. In particular, these oligosaccharides appear to regulate the expression of enzymes involved in extracellular matrix remodeling, such as metalloproteases and heparanase 1. Additionally, we conducted a literature review on the role of heparanases (1 and 2) in cutaneous inflammatory processes. Overall, my work has identified novel anti-inflammatory molecules, contributed to the study of heparanases in skin inflammation, and paved the way for the development of new therapeutic solutions for chronic inflammatory diseases. These findings demonstrate that this cellular model is a valuable tool for exploring the anti-inflammatory mechanisms of molecules, which can subsequently be studied in various inflammatory contexts.Les maladies inflammatoires chroniques constituent un problème de santé majeur, dont l’incidence est en constante augmentation. Malheureusement, les thérapies actuelles sont encore insuffisantes pour espérer une rémission de ces maladies. La recherche de nouvelles molécules anti-inflammatoires, associée à une meilleure compréhension des mécanismes inflammatoires, comme le remodelage de la matrice extracellulaire, permettra de mettre en évidence de nouvelles cibles thérapeutiques pertinentes. Les objectifs de mon travail de thèse ont été de mettre en place un modèle basé sur les macrophages et d’évaluer les propriétés anti-inflammatoires de molécules naturelles (oligosaccharide) et bio-inspirées (semi-synthétique et de synthèse). Les effets des molécules ont été confirmés en mesurant la production de marqueurs inflammatoires comme l’IL-6 et le TNF-alpha, l’activation de voies de signalisation inflammatoires ERK, JNK, p38, Akt et l’utilisation de modèles murins in vivo. Nous avons notamment mis en évidence les propriétés anti-inflammatoires des flavones pharmaco-modulées et leur mécanisme d'action dans le traitement de la douleur chronique, ainsi que d’oligosaccharides dérivés du λ-carraghénane dans le traitement du psoriasis. Ces derniers semblent notamment contrôler l’expression d’enzymes impliquées dans le processus de remodelage de la matrice extracellulaire, comme les métalloprotéases et l’héparanase 1. Enfin, nous avons réalisé une étude bibliographique sur le rôle des héparanases (1 et 2) dans les processus inflammatoires cutanés. Dans l’ensemble, mes travaux ont permis de mettre en évidence de nouvelles molécules anti-inflammatoires, de contribuer à l’étude des héparanases dans l’inflammation cutanée et ils ouvrent la porte au développement et à l’application de nouvelles solutions thérapeutiques pour les maladies inflammatoires chroniques. Ces résultats démontrent que ce modèle cellulaire est un outil pertinent pour explorer les mécanismes anti-inflammatoires des molécules, qui peuvent ensuite être étudiées dans une variété de contextes inflammatoires
Losing the common: evidence of long-term decline of a widely distributed and cold-adapted Lizard using opportunistic citizen-science data
No full textInternational audienc
Quantitative Visualization of Flows Upstream and Downstream of an Obstacle impinged by a Jet Using Dual S-PIV : Application to Aeroacoustics
No full textInternational audienceThe results presented here concern studies related to air treatment and ventilation flows in habitableenclosures. These studies fall within a broader context linked to human health and well-being,comfort, indoor environmental quality, and energy savings. Indeed, in certain configurations,impinging jets used in such enclosures can generate whistling noises, which are perceived as acousticnuisances. Moreover, if the mixing is suboptimal, these jets can also cause unpleasant drafts foroccupants.To address this, we experimentally simulated such flows and investigated the characteristics of thevortex structures generated by jets impinging on ventilation grilles. Within this framework, the noiseproduced by a jet impacting a slotted surface was studied experimentally. Experiments wereconducted for an impingement distance of 4 cm and two Reynolds numbers, 4700 and 4800. Theselection of these Reynolds numbers was based on an analysis of the evolution of radiated acousticpressure as a function of Reynolds number.An experimental setup was specifically designed for this study to allow for a quantitative analysis ofthe correlations between vortex dynamics upstream and downstream of the slotted plate struck by thejet, and the radiated acoustic field. To this end, an optical system was specifically developed toperform simultaneous visualizations of the upstream and downstream flows via quantitative lasertomography, using a dual Stereo-PIV (S-PIV) configuration. In addition to this optical setup, fourhigh-speed cameras equipped with Scheimpflug adapters were used for these quantitativevisualizations. The kinematic fields obtained at high temporal resolution (3000 Hz) enabled a detailedtracking of energy transfer from the turbulent flow to the acoustic field.The application of the λ2 vortex detection criterion to the kinematic fields acquired by S-PIV, with atemporal resolution of 0.33 ms and a spatial resolution of 0.75 mm, allowed us to track the vortexstructures during their convection through the flow. The energy, convection velocity, and trajectoriesof these vortices were also analyzed and quantified. By combining this detection criterion with aspectral comparison between acoustic frequency content and velocity signals at various locations, wewere able to assess the correlations between the deformation of vortical structures upon impact withthe edges of the slit and the resulting sound generation due to the establishment of self-sustainedacoustic feedback loops.The results show that significant increases or decreases in the acoustic pressure level are alwaysassociated with changes in the organization of vortex structures. When transitioning from Re = 4700to Re = 4800, an 8 dB drop in acoustic pressure level was observed. Spectral analysis revealed a shiftfrom a self-sustained tonal feedback loop at a single frequency (204 Hz) to a dual-frequency loop (129 Hz and 270 Hz). The analysis of vortex dynamics indicates that this drop is due to a transition from asymmetric to an antisymmetric vortex organization. The use of correlation functions between acousticsignals and velocity signals confirms the presence of aeroacoustics coupling.Les résultats présentés ici concernent des travaux relatifs à des écoulements de traitement et derenouvellement d’air dans les enceintes habitables. Ces travaux s’insèrent dans une problématiqueplus générale liée à la santé et au bien-être des personnes, au confort et à la qualité desenvironnements intérieurs, ainsi qu’aux économies d’énergie. En effet, les jets impactants utilisés dansles enceintes habitables produisent dans certaines configurations, des sifflements qui constituent desnuisances sonores. Par ailleurs, si le mélange n’est pas optimal, ils peuvent également produire dessensations de courant d’air désagréables pour les utilisateurs. Ainsi, nous avons simuléexpérimentalement ces écoulement et étudié les caractéristiques des structures tourbillonnairesgénérées par ces jets qui viennent impacter les grilles de soufflage.Dans ce contexte, le bruit d’un jet impactant une surface fendue a été étudié expérimentalement. Lesexpériences ont été réalisées pour une distance d’impact de 4 cm et avec deux nombres de Reynolds,de 4700 et 4800. Le choix de ces nombres de Reynolds découle de l’analyse de l’évolution despressions acoustiques rayonnées en fonction de la progression du nombre de Reynolds.Un dispositif expérimental a été spécialement conçu pour cette étude afin de permettre l’analysequantitative des corrélations entre les dynamiques tourbillonnaires en amont et à l’aval de la plaquefendue heurtée par le jet, avec le champ acoustique rayonné. Pour ce faire, nous avons développéspécifiquement pour ce projet, un dispositif optique permettant la réalisation de visualisationssimultanées, par tomographie quantitative Laser, des écoulements en amont et à l’aval de la plaqueimpactée par le jet, par une double Stéréo-PIV. En complément de ce dispositif optique, 4 camérasrapides équipées de leurs Scheimpflugs ont été utilisées pour ces visualisations quantitatives. Ainsi,les champs cinématiques obtenus avec une haute résolution temporelle (3000 Hz) nous ont permis desuivre finement les transferts énergétiques du champ turbulent au champ acoustique.L’application du critère λ2, de détection des structures tourbillonnaires aux champs cinématiquesobtenus par S-PIV avec une résolution temporelle de 0,33 ms et une résolution spatiale de 0,75 mmnous a permis de suivre les structures tourbillonnaires lors de leurs convections dans les écoulements.L’énergie, la vitesse de convection et les trajectoires de ces structures tourbillonnaires ont égalementété analysées et quantifiées. Ainsi, l’utilisation d’une part de ce critère de détection et lesconfrontations d’autre part des spectres de fréquences acoustiques avec ceux des signaux de vitesses en différentes positions nous ont permis d’analyser les corrélations entre les déformations desstructures tourbillonnaires au moment de l’impact sur les bords de la fente et la production sonoresuite à l’installation de boucles de sons autoentretenus.Les résultats montrent qu’une forte hausse ou une forte baisse du niveau de la pression acoustique esttoujours produite par un changement de l’organisation des structures tourbillonnaires. En passant deRe = 4700 à Re = 4800, nous relevons une chute de 8 dB du niveau de pression acoustique. Lesspectres montrent un passage de boucle de sons auto-entretenus à une seule fréquence 204 Hz versune boucle à deux fréquences 129 Hz et 270 Hz. L’analyse de la dynamique tourbillonnaire révèle quecette chute est due à un passage d’une organisation tourbillonnaire symétrique pour le premierécoulement à une organisation tourbillonnaire antisymétriques pour le second. L’exploitation de lafonction de corrélation entre le signal acoustique et les signaux de vitesses confirme ce couplageaéroacoustiqu
High-resolution acoustic recordings of wild free-ranging short-beaked common dolphins for etho-acoustical and repertoire studies
No full textPublisher: Copernicus GmbHInternational audienceDolphins are highly vocal cetaceans with a complex acoustic repertoire. These marine mammals rely heavily on sound for critical activities: echolocation clicks for navigation and prey detection, whistles for social communication, and pulsed sounds for less well-documented purposes. Understanding their acoustic behaviour is essential for insights into their ecology, social structure, and responses to anthropogenic noise. However, to date, there has been a lack of open-access datasets of acoustic recordings of wild free-ranging short-beaked common dolphins (Delphinus delphis) coupled with observational data. Here, we present a new dataset (https://doi.org/10.5281/zenodo.14637674, Lehnhoff, 2025a) of high-resolution acoustic recordings of (D. delphis) observed in various behavioural states, including foraging, travelling, socializing, milling, and attraction to the boat. The dataset was collected in the northern Bay of Biscay, France, in the summers of 2020 to 2022 during surveys conducted as part of the DOLPHINFREE project. Audio recordings were made during opportunistic encounters using two devices: a single high-quality hydrophone (sampling rate 512 kHz and bit depth 32 bits) and a compact array of four hydrophones (256 to 512 kHz and 16 to 24 bits) for localization purposes. The dataset comprises over 400 min of unedited audio recordings of D. delphis accompanied by visual observations. In total, we identified about 68 000 echolocation clicks, 4600 whistle contours, and more than 350 pulsed sounds. This comprehensive resource is invaluable for detailed studies of the acoustic repertoire of (D. delphis), coupled with behavioural studies or analyses of the directionality of their acoustic emissions
Total variations reduction for an exact control applied to a dynamical mechanical system
No full textInternational audienceIn an optimal control strategy, an important point is to define the cost of the control. Usually it is added to thecontrol criterion and multiplied by a small coefficient denoted by ε which is known as the marginal cost of the control. The keyidea of this paper, is to introduce a smoothing term in the control cost which aims at reducing the quantity of energy spent andreducing the oscillations of the control. Then using a so-called asymptotic control based on the smallness of ε, we construct anexact control which can be implemented in a close loop. The energy involved in the control depends mainly on the variation ofthe control. Therefore it seems natural to include this quantity (the total variations) in the criterion involved in the optimal control.This can be done approximately by introducing the L1 norm of the first order derivative of the control. The control strategy thatwe develop in this paper can be applied to such linear models. One important and new point is that we focus on exact controlstrategies for a non-differentiable criterion because of the cost of the control. Following the ideas of Tykhonov regularizationmethod, it is proved using the so-called asymptotic method based on the smallness of the marginal cost of the control, that theexact control suggested is the one which represents the minimum of the marginal cost among exact controls. Furthermore, andit is the main technical point, it can reduce the variations of the control with an adequate tuning of the various parameters of thecontrol loop. We test the method on three examples. The first one concerns an elementary case just to show that the algorithmworks on a reference situation. The second one is the control of flight of a flying boat with foils. We describe in the appendixthe mechanical model which can be instable because of a negative damping. The third example concerns the America’s cup boatLuna Ross
Reliability of the laboratory cob specimens manufacturing: Variability of hygrothermal properties at the wall scale
No full textInternational audienceThis article investigates how cob specimens manufactured in a laboratory are representative of a real-scale cob wall. Emphasis is placed on hygrothermal properties, which are a significant asset for reducing energy costs of buildings. It is a continuation of a previous paper in which the natural variability of the manufactured cob samples was evaluated at the material scale (laboratory samples) (Tchiotsop et al., 2022). Indeed, numerous works propose various laboratory fabrication protocol parameters and approaches for the cob specimens. Hence, a 3.2 m2 cob wall with 3% hemp shives content (by mass) was built, dried, and cored following a regular meshing plan. The variability of the wall specimens’ hygrothermal properties (density, thermal conductivity, volumetric heat capacity, moisture adsorption, moisture permeability, and intrinsic permeability) was measured and computed using the same protocols as in the previous article. As main results (details on the graphical abstract), the mean statistics of the dry bulk density and thermal properties showed good agreement between material and wall scales, while the variabilities were not always well represented at the material scale. For moisture transfer and storage properties, a significant gap was found in the statistics (up to 216%). Probability density functions (pdfs) of properties were assessed for both scales, and the same functions were found to be reliable. This study reveals the complexity at the real scale of cob buildings, making it difficult to obtain a representative specimen for characterization purposes
Sanctuary for vulnerable Arctic species at the Borealis Mud Volcano
No full textInternational audienceAbstract Borealis is a recently discovered submerged mud volcano in the Polar North Atlantic, differing from the numerous methane seepages previously identified in the region. Here we show in situ observations from a remotely operated vehicle (ROV), capturing the release of warm (11.5 °C) Neogene sediments and methane-rich fluids from a gryphon at Borealis. The surrounding seafloor within the mud volcano features extensive carbonate deposits, indicating prolonged diffuse methane migration. Sampling and imagery reveal that Borealis supports unique habitats adapted to low-oxygen conditions near methane seeps. Additionally, the irregularly shaped carbonate structures serve as a natural shelter from bottom trawling and a substratum for sessile fauna and may function as nursery grounds for threatened fish species. This discovery underscores the ecological significance of cold seep ecosystems in the Polar North Atlantic, highlighting their role in biodiversity by serving as refuges for marine species and emphasizing the need for their conservation
