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Imagerie électro-ultrasonore ultrarapide du couplage neuromusculaire
No full textSession PostersInternational audienc
Experimental and numerical analysis of heat transfer and thermal deformation in small-dimension liquid mechanical seals
No full textInternational audienceThis paper presents an experimental and numerical analysis of heat transfer and thermal deformation in small- dimension (1.4 mm) liquid mechanical seals operating in an unstable dynamic tracking mode. The studied non-contacting mechanical seal is used in a liquid pump for turbojets. The study aims to estimate the values of pressure, temperature, and thermal deformations that can prevent excessive wear of the sealing rings and control the increase in leakage rate or power loss during operation. Experimental investigations were conducted under a nominal inner pressure of 0.7 MPa, across a wide range of rotational speeds (from 1000 to 6000 rpm), and at low Reynolds numbers (Re < 70). Two high-viscosity fluids, glycerol and engine oil, were used as sealing fluids. Rotational speeds and inner pressure were set as boundary conditions in the simulations. Temperatures measured by thermocouples during the experiments were used to compare with the simulation results. Simulations were performed using the computational fluid dynamics (CFD) software COMSOL. The two-dimensional numerical models accounted for thermal transfers and face seal deformations, coupled with the pressure field in the lubrication fluid. The effects of various sealing fluids and rotational speeds on the time-dependent behavior of temperature, displacement, and pressure within the thin liquid lubricant film were investigated. Subsequent comparisons between experimental and numerical results, particularly for temperature data measured by thermocouples under various operating conditions, demonstrated strong consistency. The greatest discrepancy observed was less than 1.2 degrees C
Influence of geological heterogeneities on thermal behaviour of Lascaux Cave for conservation purposes
No full textInternational audienceThe conservation of cultural heritage is becoming an increasingly significant social issue because of climate change. Lascaux Cave, a UNESCO World Heritage Site, is particularly susceptible to disruption, which could result in the alteration of its delicate microclimate and accelerate the deterioration of the decorated walls. To mitigate the impact of these changes, it is essential to gain a deeper understanding of the thermal behaviour within the cave and its surrounding environment. The objective of this study was to examine the thermal behaviour of the cave, with a particular focus on the interactions between external temperature fluctuations, geological heterogeneity, and the internal microclimate of the cave. To investigate this phenomenon, a thermal monitoring system comprising 21 sensors (ALMEMO PT-100) was strategically placed in different zones of the cave, and a thermal station was installed outside the cave. The findings of this study demonstrate a substantial correlation between external and internal temperatures, exhibiting notable phase shifts and relative amplitude changes at varying depths and locations within the cave. The combination of thermal data with the geological heterogeneity of the rock mass demonstrated that the distinct thermal properties of different geological formations exert a considerable influence on thermal wave propagation. Furthermore, we examined how natural convection is caused by temperature differences between the vault and the ground of the cave and between the upper and lower galeries. The findings of this study can be used to develop future thermoaeraulic simulations. Understanding these thermal dynamics is necessary for developing effective conservation strategies.</div
Correction: Tracking repeat spawning anadromous fish migrations over multiple years in a fragmented river suggests philopatry and sex‑linked variation in space use
No full textInternational audienceCorrection: Aquatic Sciences (2024) 86:34 https://doi.org/10.1007/s00027-024-01048-
Unexpected increase in ompA-genotype L1 variants responsible for anorectal lymphogranuloma venereum in France.
No full textInternational audienc
cMFA for multi-omics data integration in microbial community models
No full textInternational audienceMicrobial communities are an essential component of plant health, helping in nutrient acquisition and defense against pathogens. Despite their importance, the mechanisms behind their assembly and regulation remain poorly understood. Advances in sequencing and measuring technologies have enabled the collection of multi-omics data, including population counts on the abundance of microorganisms, metabolomic data on metabolite consumption and production, and metatranscriptomic data on gene activity within these communities. In order to answer the question of how these microorganisms function in the community and interact with one another, our main objective is to develop a mathematical model of dynamic systems capable of integrating these time series of multi-omics data at a community scale. Such a model will help to better decipher the functioning of the microbial community and understand its composition, knowing what each individual consume and produces. To achieve this goal, we introduce the community-scale metabolic flux analysis (cMFA) method. In this poster, we introduced the cMFA method, that we assessed on synthetic data from a dynamic model of increasingly complex microbial communities, built upon metabolic models of microorganisms. The observed growth rates were obtained from the spline smoothing of several replicates of the community dynamics. Synthetic meta-transcriptomic data were produced from metabolic fluxes in the dynamic model. Different regularization terms were tested, including different levels of sparsity, for a cross-validated penalty weight. The cMFA method, implemented in Python with OSQP, a software package dedicated to quadratic programming problems, allows for the recovery of the functioning of microbial individuals from multi-omics data acquired at the community scale during growth experiments
Shape-tailored semiconductor dot-in-rods: optimizing CdS-shell growth for enhanced chiroptical properties <i>via</i> the rationalization of the role of temperature and time
No full textInternational audienceColloidal chemistry provides an assortment of synthetic tools for tuning the shape of semiconductor nanocrystals. To fully exploit the shape-and structure-dependent properties of semiconductor nanorods, high-precision control on growth and design is essential. However, achieving this precision is highly challenging due to the high temperatures (>350 °C) and short reaction times (<8 minutes) often required for these reactions. In this study, we performed the first investigation on the impact of temperature and time on the CdS-shell growth of CdSe/CdS quantum rods. Our findings demonstrate that temperature plays a pivotal role in achieving ultra-thin shell dot-in-rods, which are crucial for enhancing chiroptical properties. The two-step process proposed here explains the shell growth of CdSe/CdS dot-in-rods (DRs). It involves finely-tuned isotropic shell growth in the first stage, followed by anisotropic length growth along the [0001] rod axis in the second step. This approach has two advantages: a systematic control of the shell thickness for different aspect ratios (ARs) and batch monodispersity. These DRs, with an ultra-thin CdS shell and a high AR, after modification with L/D cysteine molecules, exhibit significant enhancement of their ligand-induced chirality, with circular dichroism (CD) g-factor values as high as 10-3
Un schéma préservant l'asymptotique pour le modèle M1 du transport thermique non-local pour des maillages structurés et non structurés
No full textThe M1 moment model for electronic transport is commonly used to describe non-local thermal transport effects in laser-plasma simulations. In this article, we propose a new asymptotic-preserving scheme based on the Unified Gas Kinetic Scheme (UGKS) for this model in two-dimensional space. This finite volume kinetic scheme follows the same approach as in our previous article [14] and relies on a moment closure, at the numerical scale, of the microscopic flux of UGKS. The method is developed for both structured and unstructured meshes, and several techniques are introduced to ensure accurate fluxes in the diffusion limit. A second-order extension is also proposed. Several test cases validate the different aspects of the scheme and demonstrate its efficiency in multiscale simulations. In particular, the results demonstrate that this method accurately captures non-local thermal effects.</div
Disordered optical metasurfaces: basics, properties, and applications
No full textInternational audienceOptical metasurfaces are conventionally viewed as organized flat arrays of photonic or plasmonic nanoresonators, also called metaatoms. These metasurfaces are typically highly ordered and fabricated with precision using expensive tools. However, the inherent imperfections in large-scale nanophotonic devices, along with recent advances in bottom-up nanofabrication techniques and design strategies, have highlighted the potential benefits of incorporating disorder to achieve specific optical functionalities. This review offers an overview of the key theoretical, numerical, and experimental aspects related to the exploration of disordered optical metasurfaces. It introduces fundamental concepts of light scattering by disordered metasurfaces and outlines theoretical and numerical methodologies for analyzing their optical behavior. Various fabrication techniques are discussed, highlighting the types of disorder they deliver and their achievable precision level. The review also explores critical applications of disordered optical metasurfaces, such as light manipulation in thin film materials and the design of structural colors and visual appearances. Finally, the article offers perspectives on the burgeoning future research in this field. Disordered optical metasurfaces offer a promising alternative to their ordered counterparts, often delivering unique functionalities or enhanced performance. They present a particularly exciting opportunity in applications demanding large-scale implementation, such as sustainable renewable energy systems, as well as aesthetically vibrant coatings for luxury goods and architectural designs
Syndromic and biological screening for sexually transmitted infections in female sex workers in Côte d’Ivoire: the ANRS 12381 PRINCESSE cohort study
No full textInternational audienceBackground Female sex workers (FSWs) are at high risk of contracting STIs, in particular in Sub-Saharan Africa. The implementation of oral HIV pre-exposure prophylaxis provided an opportunity to draw attention to the sexual health needs of FSWs. Innovative strategies to screen for and reduce the burden of STIs is thus a priority. This study describes STI screening among FSWs enrolled in the PRINCESSE project in Côte d’Ivoire. Methods The PRINCESSE project (2019–2023) was an interventional cohort of FSWs ≥18 years, evaluating a comprehensive, community-based sexual and reproductive health care package, including the management of STIs, offered through mobile clinics operating on prostitution sites in San Pedro area. HIV testing and syndromic STI testing were offered at baseline and every 3 months. Biological testing of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) was offered annually. Clinical forms included sociodemographic, behavioral and sex-work-related characteristics. We describe baseline characteristics, coverage of clinical examination, and vaginal, anal swab collection. Social, behavioral and sex work-related factors associated with an STI syndromic diagnosis were explored. A multivariable logistic regression model was used to identify factors associated with diagnosing a symptomatic STI. Results 489 FSWs were included in the PRINCESSE cohort. Median age was 29 years (24–35 years), 28.6% had had sex without a condom in the last 7 days. The prevalence of HIV at baseline was 10.5%. Only one case of HIV seroconversion was observed during the project. The most frequent symptom was ano-vaginal discharge (19.1%). The prevalence of STI based on clinical symptoms was 26.6%. The proportion of vaginal swab samples for which the PCR result was positive was 8.0% for CT and 4.0% for NG. Only age remained significantly associated with diagnosing a symptomatic STI in the multivariable analysis. Conclusion This study revealed a high prevalence of HIV and STIs, similar to national estimates among FSWs enrolled in a sexual health cohort. Screening for these generically asymptomatic bacterial STIs must be combined with the syndromic approach used in key populations, especially with the introduction of new PrEP programs, to reduce the exposure of individuals in these populations to STIs