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Simulation de la propagation acoustique par méthode WAPE pour le calcul des espaces actifs et de détection, application au suivi d'oiseaux de montagne
No full textBioacoustique et acoustique environnementale; GABE - Acoustique du Bâtiment et de l'Environnement: GBIO - BioacoustiqueNational audienceDans les environnements où la topographie ou les effets météorologiques influencent fortement la propagation acoustique, la détermination des espaces actifs et des espaces de détection n'est pas triviale. Un effort de modélisation de la propagation acoustique peut alors apporter des informations utiles pour comprendre l'influence du milieu sur les réseaux de communication, interpréter des données de terrain issues d'enregistrements sonores ou concevoir un réseau d'enregistreurs autonomes. Nous présenterons un modèle numérique de la propagation basé sur la résolution d'une équation parabolique grand angle (WAPE) pour le calcul de l'espace actif, puis de l'espace de détection en appliquant le principe de réciprocité. L'application au cas du suivi acoustique en milieu montagneux d'une population de lagopèdes alpins sera détaillée et discutée en référence à des données de terrain (topographie, météorologie, bruit de fond, enregistrements sonores, analyse de l'activité vocale)
Imagerie ultrasonore 3-D avec des sondes parcimonieuses pour l’estimation du mouvement
No full textSession Posters;National audienceL’imagerie par ultrasons est largement utilisée dans la pratique clinique pour mesurer le flux sanguin, jouant un rôle crucial dans le diagnostic des maladies cardiovasculaires (par exemple, l’athérosclérose), où l’évaluation de la vitesse du flux est essentielle. Cependant, les techniques bidimensionnelles conventionnelles sont limités à l’estimation 2-D. Une caractérisation hémodynamique complète nécessite une reconstruction vectorielle tridimensionnelle du champ d’écoulement vasculaire. Pour remédier à cette limitation, cette étude propose une nouvelle méthode d’estimation du mouvement en 3-D basée sur : (1) une sonde spirale parcimonieuse, réduisant le nombre d’éléments actifs pour permettre l’imagerie en 3-D avec une complexité de calcul moindre ; (2) l’ouverture synthétique comme séquence d’imagerie ; (3) une méthode d’estimation du mouvement combinant des oscillations transverses en 3-D avec un estimateur basé sur la phase. L’approche proposée a d’abord été validée par des simulations Field II puis appliquée expérimentalement avec un sonde spirale 2D de 256 éléments connecté au système ULA-OP 256. Un fantôme homogène se déplaçant à une vitesse constante a été simulé et utilisé. La précision de l’estimateur de mouvement 3-D a été évaluée en comparant le déplacement moyen estimé avec le mouvement réel dans différentes régions d’intérêt. Les résultats ont montré une forte concordance entre le déplacement réel et le déplacement estimé, avec une erreur relative inférieure à 6%. Une amélioration supplémentaire de l’estimateur et son application à l’estimation du mouvement du flux sont en cours d’étude
Can we predict the magnetic loss of a nanocrystalline core from LCR-meter characterization?
No full textInternational audienceNanocrystalline cores are key for high-frequency applications due to their low hysteresis losses, but predicting dynamic losses remains challenging. This study explores using LCR-meter-based permeability spectroscopy (μS) to characterize these materials and predict losses via fractional derivative models. The method offers a rapid, industry-friendly alternative to complex hysteresis setups.</div
Hybrid Electrokinetic-Plasmonic Biosensor for Fast and Sensisitve Pathogen Detection in Irrigation Water
No full textInternational audienc
Evaluation of Chemotherapy Response in Osteosarcoma Using Quantitative Ultrasound: A Pilot Study Relating Ultrasound Parameters to Molecular Response
No full textInternational audienceObjectives: Currently, the response to chemotherapeutic treatment for most solid tumors is assessed using the surgical specimen obtained after the tumor is surgically removed, following a whole chemotherapy cycle (e.g. 8 weeks). Therefore, early detection of tumor response is of paramount importance. Parameters derived from the backscatter coefficient (BSC) and envelope statistics provide information on tissue microstructure and may therefore be of interest for monitoring therapies that induce morphological changes in the tumor. In this study, our objective was to detect ex vivo early response to chemotherapy in ex vivo murine osteosarcoma model.Material an Methods: BSC-derived parameters using Lizzi-Feleppa approach and the Gaussian model and envelop statistics parameters using Nakagami and Homodyned-K distributions were extracted on control and treated tumors. Tumors received either 2, 4, or 5 doses of chemotherapy. To investigate the underlying causes of changes in ultrasound parameters, histological and molecular analyses (RNA sequencing) were conducted.Results: Although the tumor models show resistance to chemotherapy as evidenced by continued tumor growth at the therapeutic dose used, significant differences between treated and control tumors were observed in several BSC-derived and envelope statistics parameters depending on the number of treatments received.Conclusion: These differences might reflflect early molecular changes occurring before the establishment of chemoresistance mechanisms. They might be attributed to morphological changes linked to the underexpression of genes involved in chromatin condensation and/or collagen within the extracellular matrix. These initial findings require further investigation in a larger cohort
Notion en débat. Droit à la ville
No full textInternational audienceLe droit à la ville est issu des travaux d’Henri Lefebvre, situés dans la sociologie marxiste des années 1960–70. Ce n’est pas seulement un droit d’accès à la ville : c’est une critique radicale de l’appropriation, par le capital et par l’État, de l’ensemble des processus de production spatiale, que les habitants doivent se réapproprier voire autogérer. Mais le succès de la notion et son institutionnalisation, en particulier dans les textes onusiens, tendent à en occulter la portée critique
Behavioral Profiles and Sociodemographic Predictors of Planetary Health Diet Engagement Among Health Care Professionals to Inform Public Health Promotion: Cross-Sectional Study
No full textInternational audienceThe planetary health diet (PHD) promotes dietary habits that are beneficial to human health and environmental sustainability, two closely related goals of modern public health. Health care professionals are expected to lead by example and use their position to encourage their patients and communities to adopt healthier and more sustainable behaviors. However, little is known about health care professionals’ knowledge, attitudes, and behaviors (KAB) related to the PHD, which limits the ability to design targeted interventions for this key population. Objective This study aimed to analyze KAB profiles related to the PHD among French health care professionals and assess associations with individual characteristics. Methods This cross-sectional study was conducted from April 2024 to June 2024 among health care professionals. Participants were recruited using a nonprobabilistic convenience sampling method. Inclusion criteria were to be aged ≥18 years, fluent in French, and working as a health care professional at Hospices Civils de Lyon. Data were collected through an online questionnaire including sociodemographic and geographic variables, KAB items related to the PHD, and dietary intake. Adherence to the PHD was calculated using a validated scoring system. KAB items were analyzed using k-means clustering to identify distinct profiles. Associations with sociodemographic and geographic variables were explored using chi-square tests and ANOVA. Results Among 1104 respondents (n=927, 83.97% women and n=882, 79.89% aged between 30 and 59 years), 3 KAB clusters were identified: cluster 1 (“knowledge-attitude gap”; n=481, 43.57%) included professionals with good knowledge but moderate attitudes and partially consistent behaviors; cluster 2 (“high intent, low action”; n=318, 28.8 included those with strong knowledge and positive attitudes but limited behavioral change, and cluster 3 (“behavior-driven alignment”; n=305, 27.63%) included participants who reported pro-PHD behaviors despite lower knowledge and less favorable attitudes. PHD adherence was significantly associated with being female, having a vegetarian or flexitarian diet, and reporting environmental concerns (P<.01 in all cases). Conclusions Distinct KAB profiles among health care professionals suggest differing levels of engagement regarding the PHD. Findings suggest that tailored interventions addressing knowledge, attitudes, or behaviors could improve health care professionals’ alignment with planetary health goals within similar institutional contexts
Estimation of positive lightning impulse breakdown voltage for sphere-barrier-plane configuration in pressurized dry air using design of experiments
No full textInternational audienceMedium-and high-voltage gas-insulated switchgear (GIS) play a vital role in the infrastructure of electrical power transmission and distribution systems. The equipment within these substations is primarily insulated with pressurized gas to ensure optimal operational performance. Solid insulation is also used in switchgears in the form of shafts, spacers or dielectric barriers. The aim of this work is to investigate the influence of dielectric barriers on the breakdown voltage in pressurized air insulated rod-plane gaps. A design of experiments is used to optimize the number of experiments and create a model for the estimation of the breakdown. A Box-Behnken Design (BBD) was used to produce an empirical formula of the breakdown voltage as a function of multiple parameters. The investigated parameters considered in the BBD are the barrier location in the gap space, the barrier dimensions, the absolute pressure and the electric field non-uniformity factor. The obtained results indicated that the barrier effect was most significant in the arrangement with strongly non-uniform field for 1.5 bar and led to an increase of breakdown voltages
Caractérisation de l'endommagement des interfaces fibre-matrice dans les composites sous traction transverse
No full textInternational audienceCaractérisation de l'endommagement des interfaces fibre-matrice dans les composites sous traction transvers
Performance Analysis of Structure Factor Model-Based Scatterer Estimation Using the Cramér–Rao Bound
No full textInternational audienceThe ultrasound backscatter coefficient (BSC) provides insight into the properties of acoustic scatterers for the quantitative assessment of tissue microstructure. The structure factor model (SFM) is an advanced model, specifically adapted for concentrated media, that allows the extraction of key scatterer parameters from BSC measurements. These include the radius a, volume fraction ϕ, and relative impedance contrast γZ which were found close to the values of cellular structures at high frequency (∼40 MHz). In this study, we focused on deriving the Cramér-Rao bound and comparing it with the mean squared error of the BSC parameters estimated using the SFM to understand the fundamental performance limits of the estimation process. We evaluated the impact of different parameter values on estimation performance in the presence of a Gaussian noise. The results indicate that estimation becomes more challenging for low values of γZ , a, and ϕ.</div