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Corroboration in vivo mechanical strain distribution in soft tissues for pressure ulcer prevention: A comparative analysis between a simplified finite element analysis and experimental strain fields
No full textInternational audienceBasic research into the aetiology of pressure ulcers suggests that the concentration of mechanical strain in biological soft tissues is critical to their development. Direct measurement of in vivo strain is not compatible with clinical routine. To overcome this problem, several finite element models (FEM) have been proposed by the biomechanical community to estimate strain from imaging data. However, no direct experimental validation of the underlying relationships between mechanical loading and soft tissue strain distribution predicted by the model has been performed, and such validation evidence must be obtained prior to any clinical evaluation. Building on the experimental results obtained in N = 10 healthy volunteers (Zappalá et al., 2024), the relevance of the modelling hypotheses of the finite element model proposed in this study, which is based on a simplified geometric representation of the ischial region (Macron et al., 2020), was investigated. A methodology was proposed to estimate the different parameters needed to construct the model from the available MRI masks. The FEM was then used to estimate in vivo compressive and shear strains. The resulting strains were then compared with experimental data. The results show that the model assumptions lead to an overall overestimation of the compressive and shear strains in the muscle tissue, especially directly under the ischial tuberosity. Similarly, the model underestimates the strain in adipose tissue (mean error in shear strain of -0.2). This study highlights the fact that the assumptions usually made for the geometric modelling of muscle tissue (homogeneous soft tissue layer) lead to an incorrect estimation of peak strain localisation. Further work should be done to improve the representation of muscle tissue.</div
La stratégie d'implantation de la LONASE à Dakar.: Un maillage du territoire par le bas.
No full textInternational audienceContents1. problem and hypotheses2. Research context3. Methodology4. A look at the gambling market in Senegal5. The creation of a new territorial networkSommaire1. Problématique et hypothèses2. Contexte de la recherche3. Méthodologie4. Retour sur le marché des jeux d'argent au Sénégal5. La fabrique d'un nouveau maillage du territoir
The blow-up rate for a loglog non-scaling invariant semilinear wave equation
No full text28 pagesInternational audienceWe consider blow-up solutions of a semilinear wave equation with a loglog perturbation of the power nonlinearity in the subconformal case, and show that the blow-up rate is given by the solution of the associated ODE which has the same blow-up time. In fact, our result shows an upper bound and a lower bound of the blow-up rate, both proportional to the blow-up solution of the associated ODE. The main difficulty comes from the fact that the PDE is not scaling invariant
Influence of the competition in the spatial dynamics of a population of Aedes mosquitoes
No full textInternational audienceIn this article, we investigate a competitive reaction-diffusion system modelling the interaction between several species of mosquitoes. In particular, it has been observed that in tropical regions, Aedes aegypti mosquitoes are well established in urban area whereas Aedes albopictus mosquitoes spread widely in forest region. The aim of this paper is to propose a simple mathematical system modeling this segregation phenomenon. Moreprecisely, after modeling the dynamics by a competitive reaction-diffusion system with spatial heterogeneity, we prove that when there is a strong competition between these two species of mosquitoes, solutions to this system converge in long time to segregated stationary solutions. Then we study the influence of this strong competition on the success of a population replacement strategy using Wolbachia bacteria. Our theoretical results are also illustrated by some numerical simulations
Zone extrapolations in parametric timed automata
No full textInternational audienceTimed automata (TAs) are an efficient formalism to model and verify systems with hard timing constraints and concurrency. While TAs assume exact timing constants with infinite precision, parametric timed automata (PTAs) overcome this limitation and increase their expressiveness—at the cost of undecidability of most interesting problems. A practical explanation for the efficiency of nonparametric TAs is zone extrapolation, where clock valuations beyond a given constant are considered equivalent. This concept cannot be easily extended to PTAs, due to the fact that parameters can be unbounded, meaning that the constants compared to the clocks have no upper bound. In this work, we propose several definitions of extrapolation for PTAs, and we study their correctness. Our experiments show an overall decrease of the computation time and, most importantly, allow termination of some previously unsolvable benchmarks
Effect of chemical composition on mechanical properties and shear band propagation in fully-amorphous ZrCu/ZrCuAl nanolaminates
No full textInternational audienceThe mechanical behavior and propagation of shear bands (SBs) in fully amorphous ZrCu/ZrCuAl9 nanolaminates with different nanoscale bilayer period (Λ, from 200 down to 50 nm) was investigated. The combined effect of local chemistry variation and nanointerface density influences the propagation of SBs and the mechanical behavior, reporting nanoindentation hardness values above the rule of mixtures, due to severe shear displacement and strong compositional intermixing along the SB-deformed zone with diffusion of Al into ZrCu layers. Enhanced plastic deformation (> 10 %) is observed for Λ = 100 and 200 nm during micropillar compression, but accompanied by a reduction of the yield strength. In contrast, for Λ = 50 nm, deformation is dominated by catastrophic SB events, while the yield strength returns to that of the monolithic films of ∼2–2.5 GPa. Our results can be utilized in design of nanostructured metallic glasses with tailored mechanical performance
Différences de processus anticipatoires entre l'initiation de la marche et du pas
No full textInternational audienc
Entretien avec Achim Szepanski: in Vincent Chanson (dir.), Techno & co. Chroniques de la culture dance électronique, Paris, Amsterdam, 2025
No full textVincent Chanson, Interview with Achim Szepansk
Danser et mourir : l’obsolescence et l’esthétique incorporée de l’accélération: in Vincent Chanson (dir.), Techno & co. Chroniques de la culture dance électronique, Paris, Amsterdam, 2025
No full textBenjamin Noys, “Dance and die: Obsolescence and embedded aesthetics of acceleration”, In Francisco Martinez (ed.), Accelerated youth, Tallinn, Tallinn University Press, p. 291–30
