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Softmin Discrete Minimax Classifier for Imbalanced Classes and Prior Probability Shifts
No full textInternational audienceThis paper proposes a new approach for dealing with imbalanced classes and prior probability shifts in supervised classification tasks. Coupled with any feature space partitioning method, our criterion aims to compute an almost-Bayesian randomized equalizer classifier for which the maxima of the class-conditional risks are minimized. Our approach belongs to the historically well-studied field of randomized minimax criteria. Our new criterion can be considered as a self-sufficient classifier, or can be easily coupled with any pretrained Convolutional Neural Networks and Decision Trees to address the issues of imbalanced classes and prior probability shifts. Numerical experiments compare our criterion to several state-of-the-art algorithms and show the relevance of our approach when it is necessary to well classify the minority classes and to equalize the risks per class. Experiments on the CIFAR-100 database show that our criterion scales well when the number of classes is large
Security and energy-efficiency in the Internet of Things: Challenges and solutions
No full textNational audienceThe Internet of Things (IoT) is a breakthrough that empowers our everyday life. It allows real-time data analytics, improves industrial production, or provides tailored services. IoT networks deploy many small devices that are energy-constrained. Furthermore, IoT networks and applications lack efficient security. Several attacks occurred against IoT networks due to insufficient security in the past years. However, when security solutions are integrated into IoT networks, they drastically increase the energy consumption of those networks, thus, reducing their lifetime. A major question arises: is it possible to find trade-offs between ensuring security and the energy consumption of security? In this paper, we present a summary of the work done during the thesis, which is the guideline for the corresponding presentation
General tests of conditional independence based on empirical processes indexed by functions
No full textInternational audienceThis paper focuses on nonparametric procedures for testing conditional independence between random vectors using Möbius transformation. We derive a method predicated on general empirical processes indexed by a specific class of functions. Conditional half-space and conditional empirical characteristic processes are used to demonstrate two abstract approximation theorems and their applications in real-world situations. We conclude by describing the limiting behavior of the Möbius transformation of the empirical conditional processes indexed by functions under contiguous sequences of alternatives. Our results are proved under some standard structural conditions on the Vapnik-Chervonenkis classes of functions and some mild conditions on the model. Monte Carlo simulation results indicate that the suggested statistical test for indepen- dence behaves reasonably well in finite samples
On Weak Convergence of the Bootstrap Copula Empirical Process with Random Resample Size
No full textInternational audienceThe purpose of this note is to provide a description of the weak convergence of the random resample size bootstrap empirical process. The principal results are used to estimate the sample rank correlation coefficients using Spearman’s and Kendall’s respective methods. In addition to this, we discuss how our findings can be applied to statistical testing
Induction de Lebesgue et théorème de Tonelli en Coq
No full textLebesgue integration is a well-known mathematical tool, used for instance in probability theory, real analysis, and numerical mathematics. Thus, its formalization in a proof assistant is to be designed to fit different goals and projects. Once the Lebesgue integral is formally defined and the first lemmas are proved, the question of the convenience of the formalization naturally arises. To check it, a useful extension is Tonelli's theorem, stating that the (double) integral of a nonnegative measurable function of two variables can be computed by iterated integrals, and allowing to switch the order of integration. This article describes the formal definition and proof in Coq of product sigma-algebras, product measures and their uniqueness, the construction of iterated integrals, up to Tonelli's theorem. We also advertise the Lebesgue induction principle provided by an inductive type for nonnegative measurable functions.L'intégrale de Lebesgue est un outil mathématique bien connu, utilisé par exemple en théorie des probabilités, en analyse réelle et pour les mathématiques appliquées. Sa formalisation dans un assistant de preuve doit donc être conçue pour s'adapter à des buts et des projets différents. Une fois que l'intégrale de Lebesgue est définie formellement et que les premiers lemmes sont prouvés, il se pose naturellement la question de la commodité d'usage de la formalisation. Pour la contrôler, le théorème de Tonelli est une extension utile. Ce dernier établi que l'intégrale (double) d'une fonction mesurable positive de deux variables peut être calculée par des intégrales itérées et que l'on peut intervertir l'ordre d'intégration. Cet article décrit la définition formelle et la preuve en Coq des tribus produits, de l'existence et l'unicité des mesures produits, de la construction des intégrales itérées, jusqu'au théorème de Tonelli. Nous mettons également en avant le principe d'induction de Lebesgue, obtenu à partir d'un type inductif pour les fonctions mesurables positives
Synthesis and study of new siderophore analog-ciprofloxacin conjugates with antibiotic activities against Pseudomonas aeruginosa and Burkholderia spp.
No full textInternational audienceAntibacterial resistance is a healthcare burden. Among Gram-negative bacteria, Pseudomonas aeruginosa belongs to the first list of antibiotic-resistant "priority pathogens" described by the World Health Organization. Formerly Pseudomonas pseudomallei, Burkholderia pseudomallei, responsible for melioidosis, is considered as a potential bioterrorist weapon by the Centers of Diseases Control and Prevention. We are interested in the development of new ways to combat these bacteria, targeted due to their high level of resistance to antibiotics via a lack of membrane permeability or efflux. Using iron transport systems is a promising strategy to bypass the bacteria cell membrane and restore the activity of conventional antibiotics such as ciprofloxacin. Specific outer membrane receptors are necessary to most microbes as they allow iron uptake, essential for their survival through siderophore-dependent mechanisms. These systems may allow the introduction of antibacterial agents, chemically coupled to a natural or synthetic siderophore molecule to form siderophore-antibiotic conjugates. In this work, we describe the synthesis of six new siderophore analog-ciprofloxacin conjugates including cleavable linker or not. The siderophore analogs correspond to a mono-catechol or a hydroxypyridinone moiety recognized by both Pseudomonas and Burkholderia species. Physico-chemical studies showed that (i) conjugates were unable to interact or cross the membrane by passive diffusion and (ii) conjugates with cleavable linker are stable in physiologic environment. Biological evaluations have highlighted a promising compound 2d, bearing an hydroxypyridinone moiety with a cleavable linker, active on a large panel of strains of Pseudomonas aeruginosa, Burkholderia pseudomallei and Burkholderia thailandensis without toxicity observed in vitro
Flow rate variations in microfluidic circuits with free surfaces
No full textInternational audienceWe investigate analytically and experimentally the flow rate througha biochip in a circuit involving a peristaltic pump and reservoirs withliquid/air interfaces. Peristaltic pumps are a convenient way to achieverecirculation in microfluidic circuits. We consider different cases: reservoirs in contact with ambient air, tight reservoirs, and imperfect tightnessleading to air or liquid leaks. We demonstrate that if changes inhydraulic resistance are slow enough, i.e. if cells do not proliferate toofast, the system may reach an equilibrium, with a difference in liquid height between inlet and outlet reservoir compensating the pressuredrop in the biochip. We compute the flow rate through the biochipin the transient regime as well as the characteristic time. We alsoshow that depending on the circuit dimensions, this equilibrium maynever be reached. We provide guidelines to design tubings and reservoirs to avoid this situation and ensure a smooth recirculation at adesired flow rate, which is a necessary condition for dynamic cell culture
Écritures de l’exil au féminin : de la transgression au métissage(Italie-Méditerranée, XIXᵉ-XXᵉ siècle)
No full textCe document a été généré automatiquement le 11 décembre 2023. Le texte et les autres éléments (illustrations, fichiers annexes importés), sont « Tous droits réservés », sauf mention contraire.Ce numéro étudie l’écriture des auteures en exil, volontaire ou imposé, dans l’espace méditerranéen, entre le XIXe et le XXe siècles. Il vise à faire connaître et à valoriser l’activité et la production littéraire et critique de ces écrivaines qui ont joué un rôle crucial, mais souvent ignoré, dans la création littéraire, contribuant de façon fondamentale au dialogue entre les langues, les cultures et les idées. L’axe temporel choisi prend en compte les expériences d’écriture d’exil, faisant de la condition « exilique » un noyau existentiel commun à toutes les expériences des sujets migrants, quelles que soient les époques, les cultures et les circonstances qui les accueillent ou les suscitent
A simple geometrically exact finite element for thin shells—Part 1: statics
No full textInternational audienceThis paper presents a new triangular nonlinear shell finite element with a novel kinematic model suitable for simulation with large displacements and rotations, herein introduced as "T6-3iKL". This element has 6 nodes, a quadratic displacement field, and a linear rotation field based on Rodrigues incremental rotation parameters, giving in total 21 degrees of freedom. The novelty of this shell element concerns a new kinematic model with properties from Kirchhoff-Love shell theory, making it possible to eliminate the drilling DOF in the rotation field (compared to Mindlin-Reissner models), approximating the rotation continuity between adjacent elements by a single scalar and allowing multiple branch connections in the mesh, making this element very simple and interesting, with no artificial parameters imputed by the code (such as penalties or Lagrange multipliers). The element permits the implementation of different material constitutive equations, including elastic anisotropic models, and the thickness of the shell is optionally allowed to change through the simulation. The model developed in this article is numerically implemented and the results compared to different references in multiple examples, showing the consistency and reliability of the new formulation. It is believed that this new versatile triangular shell element, with no necessity of artificial penalty calibration, simple kinematics, a relatively small number of DOFs, geometric exactness, the possibility to use 3D material constitutive models, and easy connection with multiple branched shells and beams, implemented together with reliable mesh generation, may be an effective option for shell simulation in many engineering applications
