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LOUIS-ANTOINE MACAREL, Aux origines du droit moderne des installations classées pour la protection de l'environnement
No full textInternational audienc
Generalized principal eigenvalues for parabolic operators in bounded domains
No full textWe introduce here new generalized principal eigenvalues for linear parabolic operators with heterogeneous coefficients in space and time. We consider a bounded spatial domain and an unbounded time interval I := R, R + or R -, and operators with coefficients having a fairly general dependence on space and time. The notions we introduce rely on the parabolic maximum principle and extend some earlier definitions introduced for elliptic operators [3, 5]. We first show that these eigenvalues hold the key to understanding the large time behavior and entire solutions of heterogeneous Fisher-KPP type equations. We then describe the relation of these quantities with principal Floquet bundles for parabolic operators which provides further characterizations of the principal eigenvalues. These allow us to derive monotonicity properties and comparisons between generalized principal eigenvalues, as well as perturbation results and further properties involving limit operators. We show that the sign of these eigenvalues encodes different versions of the maximum principle for parabolic operators. Lastly, we explicitly compute the generalized principal eigenvalues for several classes of operators such as spatial-independent, periodic, almost periodic, uniquely ergodic or random stationary ergodic coefficients
Interacting humans and robots can improve sensory prediction by adapting their viscoelasticity
No full textTo manipulate objects or dance together, humans and robots exchange energy and haptic information. While the exchange of energy in human-robot interaction has been extensively investigated, the underlying exchange of haptic information is not well understood. Here, we develop a computational model of the mechanical and sensory interactions between agents that can tune their viscoelasticity while considering their sensory and motor noise. The resulting stochastic-optimal-information-and-effort (SOIE) controller predicts how the exchange of haptic information and the performance can be improved by adjusting viscoelasticity. This controller was first implemented on a robot-robot experiment with a tracking task which showed its superior performance when compared to either stiff or compliant control. Importantly, the optimal controller also predicts how connected humans alter their muscle activation to improve haptic communication, with differentiated viscoelasticity adjustment to their own sensing noise and haptic perturbations. A human-robot experiment then illustrated the applicability of this optimal control strategy for robots, yielding improved tracking performance and effective haptic communication as the robot adjusted its viscoelasticity according to its own and the user's noise characteristics. The proposed SOIE controller may thus be used to improve haptic communication and collaboration of humans and robots
Impact of Menstrual Cycle and Oral Contraceptives on Haematological and Inflammatory Biomarkers in Highly Trained Female Athletes
No full textInternational audienceHaematological and inflammatory biomarkers play an important role in athlete performance and health, with some of them used in the fight against doping. However, little is known about how they are modulated by sex hormone fluctuations in highly trained female athletes. We therefore measured the haematological parameters monitored in the athlete biological passport (ABP) as well as erythropoietin, serum markers of iron and inflammatory statuses (iron, ferritin, transferrin, transferrin saturation, albumin, creatinine, total protein, interleukin‐6 and TNF‐alpha) in 20 highly trained female athletes: 10 with normal menstrual cycle (NMC) during the early follicular and mid‐luteal phases and 10 using a combined oral contraceptive (COC, i.e., ethinyloestradiol and levonorgestrel) during active and inactive hormone intake. Body composition, leptin and lipid profile (total cholesterol, HDL, LDL and triglycerides) were determined in parallel. No changes were observed throughout NMC phases. Irrespective of active/inactive pill intake, COC use increased transferrin, triglycerides as well as reticulocyte count ( p < 0.05) and decreased interleukin‐6 ( p < 0.05), with no significant changes in the other parameters studied. In conclusion, given our results across NMC phases in highly trained athletes, it seems warranted to investigate whether intense physical training would mitigate the impact of endogenous sex hormones on body composition and haematological and inflammatory parameters. In addition, further studies are needed to determine the extent of the changes induced by COCs on these blood biomarkers in elite female athletes when subjected to extreme environments such as intensive training or competition in humid heat, cold and/or hypoxia or when using other medications in parallel
Concentration estimates for SPDEs driven by fractional Brownian motion
No full textInternational audienceThe main goal of this work is to provide sample-path estimates for the solution of slowly time-dependent SPDEs perturbed by a cylindrical fractional Brownian motion. Our strategy is similar to the approach by Berglund and Nader for space-time white noise. However, the setting of fractional Brownian motion does not allow us to use any martingale methods. Using instead optimal estimates for the probability that the supremum of a Gaussian process exceeds a certain level, we derive concentration estimates for the solution of the SPDE, provided that the Hurst index H of the fractional Brownian motion satisfies H > ¼. As a by-product, we also obtain concentration estimates for one-dimensional fractional SDEs valid for any H ∈ (0,1)
Triplets de Markov-Hurwitz
No full textInternational audienceNous discutons puis résolvons l'équation diophantienne de Markov-Hurwitz avec les outils mathématiques du lycéen
Guanidinium‐Stapled Helical Peptides for Targeting Protein‐Protein Interactions
No full textInternational audiencePeptide stapling has emerged as a versatile approach in drug discovery to reinforce secondary structure elements especially α‐helices and improve properties of linear bioactive peptides. Inspired by the prevalence of arginine in protein‐protein and protein‐DNA interfaces, we investigated guanidinium‐stapling as a means to constrain helical peptides. Guanidinium stapling was readily achieved on solid support, utilizing two orthogonally protected lysine or unatural α‐amino acid residues with an amino function. This method allows for easy modulation of the nature and size of the staple as well as helix propensity. Evaluating a set of guanidinium‐stapled peptides for their interaction with different protein targets identified several binders with increased target affinity. X‐ray structure determination of four complexes revealed that all stapled peptides adopt a helical conformation upon protein binding. Notably, the disubstituted guanidinium generally exhibits a distinct cis / trans conformation and, in one instance, retains a conserved hydrogen bond with the protein surface. By identifying, for the first time, the guanidinium moiety as an effective helical peptide stapling group, this research significantly expands the repertoire of α‐helix stapling techniques for the creation of useful protein mimics
Contribution to the understanding of antibacterial properties of CuTiZn thin film: from crystalline alloy to metallic glass
No full textDocument version soumiseInternational audienceIn this work, thin films of CuZn and CuTiZn alloys were synthesized by magnetron sputter deposition. Their antibacterial activity on the proliferation of Escherichia coli was investigated after incubation during 24h at 37.0°C by measuring the bacteria solution absorbance at 600nm. Among tests usually employed in laboratories to evaluate the antibacterial properties of coatings, this one specially characterizes the action of chemical elements dissolved in the solution, i.e. the so-called release killing mechanism. The obtained results are discussed depending on the film chemical composition (in depth and at the surface), microstructure and crystallinity. A good antibacterial activity was found for pure Zn and CuZn films, whereas a rapid degradation was observed as soon as Ti is added, which coincides with the formation of a dense amorphous phase. At close chemical compositions, formation of this stable metallic glass phase seems to be detrimental to the ion release mechanism. This work highlighted that the microstructural and crystalline properties (more or less porous polycrystalline film / dense, defect free metallic glass) significantly influence the antibacterial properties of such alloy thin films