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EVALUATING SEGMENTATION USING BETTI-1 TOPOLOGICAL METRIC: APPLICATION TO NASAL CAVITIES IN THE CONTEXT OF AIRFLOW SIMULATION
No full textInternational audienceComputational fluid dynamics (CFD) simulations offer an objective means to analyze nasal airflow. However, to be patient-specific, their accuracy relies on precise CT-based volume segmentation of the nasal cavity. Existing segmentation methods typically prioritize volumetric accuracy (e.g., Dice coefficient) while often overlooking topological fidelity, which is critical for generating anatomically consistent CFD meshes. To address this limitation, we propose an automatic nasal cavity segmentation framework based on nnUNet, augmented with a topology-based evaluation metric that quantifies differences in the number of tunnels between predicted and reference segmentations. Evaluation on the NasalSeg public dataset shows a Dice score of 0.947, comparable to state-of-the-art results, while improving the segmentation consistency by removing tunnels
Optical sensor characterization for rapid detection of nitrogen phosphorus and potassium concentrations in soil
No full textInternational audienceAccurate and timely monitoring of soil nutrient concentrations, particularlynitrogen (N), phosphorus (P), and potassium (K), is crucial for optimizing agriculturalproductivity and minimizing environmental impact. In this study, we present thecharacterization of an optical sensor designed for the rapid and non-destructiveassessment of N, P, and K levels in soil samples. The sensor employs Visible-NearInfrared (VIS–NIR) spectroscopy to analyse the spectral signatures of soil samplesand extract quantitative information regarding nutrient concentrations. A total of30 experimental samples classified into six distinct categories, comprising varioussoil-fertilizer mixtures, were prepared to calibrate the sensor's performance. Thesesamples were made from four primary constituents: black soil (sourced from a farmin the Auvergne-Rhone-Alpes region of France), NPK (6:3:12) fertilizer, ammoniumnitrate, and urea. The six categories were grouped into two sets: sample type 1consisted of pure samples, while sample types 2 through 6 were mixtures of soiland fertilizer. The mixed samples were prepared with nutrient concentrations higherthan those typically found in agricultural soils to enable controlled calibration ofsensor performance. The pure sample, specifically Sample10, consisting of humussoil without fertilizer amendment, was included as a reference to approximatereal-soil conditions. Laboratory experiments involved illuminating the sampleswith specific wavelengths of light and measuring the intensity of reflected lightwithin a controlled environment. Calibration curves and equations specific to eachmacronutrient were developed through regression analysis using data collected fromthe experiments. Performance evaluation metrics, including Root Mean Square Error(RMSE), Coefficient of Determination (R2), Predicted Residual Error Sum of Squares(PRESS), and Standard Error (s), were employed to assess model accuracy. Resultsdemonstrated satisfactory performance across all sample types, with average R2,RMSE, PRESS, and s values of 0.7835 V, 0.0097 V, 0.0003 V, and 0.0003 V, respectively.Statistical analyses further validated the sensor, indicating average standard errorsof 0.003 V for repeatability and 0.001 V for reproducibility, along with a sensitivity of7% and a linearity of R2 = 0.8. These findings validate the effectiveness of the opticalsensor in accurately quantifying soil macronutrient concentrations
EVALUATING SEGMENTATION USING β1 TOPOLOGICAL METRIC: APPLICATION TO NASAL CAVITIES IN THE CONTEXT OF AIRFLOW SIMULATION
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Spectral vs. Spatial Pruning: Fault Resilience Analysis for Extremely Sparse DNNs
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Habiter la ville en décroissance, la transformer sans la conformer : expériences dans les fissures de l'ordre urbain à Saint-Etienne
No full textInternational audienceGrande ville à histoire industrielle située à l'ombre de la métropole lyonnaise, Saint-Étienne partage avec nombre de villes petites et moyennes une trajectoire de décroissance urbaine et un certain syndrome d'invisibilité. Le détour par la situation stéphanoise peut ainsi éclairer les spécificités des expériences de l'habiter et des mobilisations dans les villes en décroissance. Notre enquête montre que les expériences de l'habiter y sont singulières - marquées notamment par la présence des espaces vides, les transformations du peuplement et la stigmatisation urbaine - et vécues différemment selon les places occupées dans la stratification sociale. Elle éclaire aussi la façon dont des collectifs d'habitants y composent avec un système de ressources et de contraintes spécifiques pour constituer les fissures de l'ordre urbain, incarnées par les espaces vacants et délaissés, en opportunités pour (re)faire la ville autrement que selon un modèle entrepreneurial de production de l'espace
Quasi-geostrophic Rayleigh-Bénard convection on the tilted -plane
No full textInternational audienceRapidly rotating Rayleigh-Bénard convection on a -plane at colatitude is investigated numerically using an asymptotically reduced equation set valid in the limit of very rapid rotation. The equations provide a non-hydrostatic but quasi-geostrophic description in a non-orthogonal coordinate system. The tilt changes the structure of the large-scale barotropic condensate from large-scale vortices to zonal flows as the colatitude of the -plane increases, with bistable states present for certain parameter ranges, extending prior work to a geophysically significant parameter regime. This behaviour is understood through the impact of broken rotation symmetry on the barotropic source terms resulting from baroclinic vortical stresses and baroclinic torque. As the tilt angle increases, global heat and momentum transport is reduced relative to upright-polar convection, a result that is explained through linear theory and nonlinear power maps both of which demonstrate increased attenuation of the domain of dynamically active spatial scales as the convective modes depart from a North-South alignment in the horizontal plane. A key finding is that the predominance of lateral thermal mixing allows for the maintenance of a persistent unstable mean temperature gradient that saturates at increasing forcing levels and remains insensitive to the colatitude
Dark Patterns and the EU Digital Services Act: Mapping Autonomy Violations and Design Factors
No full textInternational audienceDark patterns are design practices that undermine users’ ability to make autonomous and informed choices in digital experiences. The EU Digital Services Act (DSA) seeks to protect users from such designs and their effects, with Article 25 prohibiting three autonomy violation types: deception, manipulation and distortion/impairment. Demonstrating such regulatory violations, however, requires design-oriented reasoning necessary to articulate why an observed design practice constitutes a specific autonomy violation type. This paper maps 59 known dark patterns onto the three autonomy violation types from the DSA and identifies eight new design factors which can help determine when a dark pattern violates autonomy. Our mapping of dark patterns to autonomy violations grounds ongoing regulatory debates in design while opening pathways for translational research that reimagines how HCI engages with the governance of design practices
Édition numérique du Dictionnaire universel françois et latin, vulgairement appellé Dictionnaire de Trévoux
No full textCette plateforme propose une interface de consultation numérique du Dictionnaire universel françois et latin, vulgairement appellé Dictionnaire de Trévoux
Computing the degreewidth of a digraph is hard
No full textGiven a digraph, an ordering of its vertices defines a backedge graph, namely the undirected graph whose edges correspond to the arcs pointing backwards with respect to the order. The degreewidth of a digraph is the minimum over all ordering of the maximum degree of the backedge graph. We answer an open question by Keeney and Lokshtanov [WG 2024], proving that it is NP-hard to determine whether an oriented graph has degreewidth at most 1, which settles the last open case for oriented graphs. We complement this result with a general discussion on parameters defined using backedge graphs and their relations to classical parameters