Bioévaluation de la pollution des sédiments de la Seine (région parisienne) par l'emploi d'un bioessai basé sur la croissance à court terme de la micro-algue Selenastrum capricornutum Printz

La bioévaluation de l'état de santé des fonds meubles dépend des conditions expérimentales du traitement des échantillons de sédiment conduisant à l'obtention de la phase aqueuse sur laquelle sont effectuées les analyses chimiques et toxicologiques.Au cours de cette étude préliminaire nous avons considéré l'action de ces principales conditions ; nous constatons que l'effet inhibiteur d'un sédiment vis-à-vis de la croissance à court terme de la micro-algue Selenastrum capricornutum Printz n'est pas aisément levé, que ce soit par lessivages successifs du sédiment, par filtration plus fine de l'eau extraite à partir de ce dernier ou par autoclavage préalable de ce même sédiment, il peut l'être par contre après biodégradation.Cette étude expérimentale a permis de comparer entre eux les pouvoirs inhibiteurs des fonds meubles de la Seine (région parisienne).On note qu'il n'y a pas de corrélation entre les teneurs en métaux lourds souvent importantes des eaux issues des sédiments (Pb 70, Cu 100, Cr 150, Cd 9, Ni 280, Zn 400 µg.L-1) et le développement des algues : les polluants métalliques sont masqués par le pouvoir chélateur de ces biotopes riches en substances organiques.Une conclusion à cette étude préliminaire est que l'analyse chimique des sédiments, utilisée seule, n'a qu'un intérêt limité : les données les plus fiables correspondent à celles fournies par les bioessais.A bioevaluation of the state of health of soft bottoms depends on the experimental conditions in which samples of sediment are treated to obtain the water phase to be subjected to chemical and toxicological analyses.In the course of this preliminary study we have considered the action of these principal conditions. We have noted that the inhibiting effect of a sediment on the short-term growth of a microalga Selenastrum capricornutum is not easy to eliminate, whether by a series of washes of the sediment, by a finer filtration of the water extracted from this sediment or by e previous autoclavage of this sediment.This study quickly revealed which sediments in the River Seine (Paris area) inhibited most the test micro-alga Selenastrum capricornutum (Chlorophyceae); the cause of these inhibitions was then sought.There is no correlation between the often high content of heavy metals in the sediment water (Pb 70, Cu 100, Cr 150, Cd 9, Ni 280, Zn 400 µg.L-1) and the development of the algae; the metal pollutants are probably masked by the chelating capacity of these biotopes rich in organic substances. The experimental conditions under which the sediment samples are treated to obtain the water phase used for the chemical and toxicological analyses are also important.One conclusion drawn is that a chemical analysis alone of the sediments is of limited interest. The most reliable data from the ecological point of view are those provided by the bio-assays

Madame de Genlis : de l’élaboration d’un plan éducatif à la formation d’une identité féminine

There is no well-run education without a meditated plan, organizing every moment according to the age of the student. It should be started as soon as possible, as shown by Madame de Genlis in her New Teaching Method for Early Childhood. In this original treatise, bringing together dialogues, games, stories, compositions and maxims, intended for six-twelve-year-olds, the author lays the foundations for what she considers to be the first decisive elements of instruction and education. The following stages of her educational project, from adolescence to marriage, both in their conception and content, are revealed in her Memoirs, which reveal their experimental aspect. We see Madame de Genlis as governor, facing the children of the house of Orléans. All these data shed light on Madame de Genlis\u27 educational thinking and pedagogical principles. Inspired by Rousseau and the Enlightenment, she wants to break with old models and offer new alternatives to girls by allowing them to access knowledge

Explicit formulae in probability and in statistical physics

We consider two aspects of Marc Yor's work that have had an impact in statistical physics: firstly, his results on the windings of planar Brownian motion and their implications for the study of polymers; secondly, his theory of exponential functionals of Levy processes and its connections with disordered systems. Particular emphasis is placed on techniques leading to explicit calculations.Comment: 14 pages, 2 figures. To appear in Seminaire de Probabilites, Special Issue Marc Yo

Noise Sensitivity in Continuum Percolation

We prove that the Poisson Boolean model, also known as the Gilbert disc model, is noise sensitive at criticality. This is the first such result for a Continuum Percolation model, and the first for which the critical probability p_c \ne 1/2. Our proof uses a version of the Benjamini-Kalai-Schramm Theorem for biased product measures. A quantitative version of this result was recently proved by Keller and Kindler. We give a simple deduction of the non-quantitative result from the unbiased version. We also develop a quite general method of approximating Continuum Percolation models by discrete models with p_c bounded away from zero; this method is based on an extremal result on non-uniform hypergraphs.Comment: 42 page

Functionals of the Brownian motion, localization and metric graphs

We review several results related to the problem of a quantum particle in a random environment. In an introductory part, we recall how several functionals of the Brownian motion arise in the study of electronic transport in weakly disordered metals (weak localization). Two aspects of the physics of the one-dimensional strong localization are reviewed : some properties of the scattering by a random potential (time delay distribution) and a study of the spectrum of a random potential on a bounded domain (the extreme value statistics of the eigenvalues). Then we mention several results concerning the diffusion on graphs, and more generally the spectral properties of the Schr\"odinger operator on graphs. The interest of spectral determinants as generating functions characterizing the diffusion on graphs is illustrated. Finally, we consider a two-dimensional model of a charged particle coupled to the random magnetic field due to magnetic vortices. We recall the connection between spectral properties of this model and winding functionals of the planar Brownian motion.Comment: Review article. 50 pages, 21 eps figures. Version 2: section 5.5 and conclusion added. Several references adde

MKS3/TMEM67 mutations are a major cause of COACH syndrome, a joubert syndrome related disorder with liver involvement

The acronym COACH defines an autosomal recessive condition of Cerebellar vermis hypo/ aplasia, Oligophrenia, congenital Ataxia, Coloboma and Hepatic fibrosis. Patients present the “molar tooth sign”, a midbrain-hindbrain malformation pathognomonic for Joubert Syndrome (JS) and Related Disorders (JSRDs). The main feature of COACH is congenital hepatic fibrosis (CHF), resulting from malformation of the embryonic ductal plate. CHF is invariably found also in Meckel syndrome (MS), a lethal ciliopathy already found to be allelic with JSRDs at the CEP290 and RPGRIP1L genes. Recently, mutations in the MKS3 gene (approved symbol TMEM67), causative of about 7% MS cases, have been detected in few Meckel-like and pure JS patients. Analysis of MKS3 in 14 COACH families identified mutations in 8 (57%). Features such as colobomas and nephronophthisis were found only in a subset of mutated cases. These data confirm COACH as a distinct JSRD subgroup with core features of JS plus CHF, which major gene is MKS3, and further strengthen gene-phenotype correlates in JSRDs

A Fourier Analysis Based Attack against Physically Unclonable Functions

Electronic payment systems have leveraged the advantages offered by the RFID technology, whose security is promised to be improved by applying the notion of Physically Unclonable Functions (PUFs). Along with the evolution of PUFs, numerous successful attacks against PUFs have been proposed in the literature. Among these are machine learning (ML) attacks, ranging from heuristic approaches to provable algorithms, that have attracted great attention. Our paper pursues this line of research by introducing a Fourier analysis based attack against PUFs. More specifically, this paper focuses on two main aspects of ML attacks, namely being provable and noise tolerant. In this regard, we prove that our attack is naturally integrated into a provable Probably Approximately Correct (PAC) model. Moreover, we show that our attacks against known PUF families are effective and applicable even in the presence of noise. Our proof relies heavily on the intrinsic properties of these PUF families, namely arbiter, Ring Oscillator (RO), and Bistable Ring (BR) PUF families. We believe that our new style of ML algorithms, which take advantage of the Fourier analysis principle, can offer better measures of PUF security

Probability Theory in Statistical Physics, Percolation, and Other Random Topics: The Work of C. Newman

In the introduction to this volume, we discuss some of the highlights of the research career of Chuck Newman. This introduction is divided into two main sections, the first covering Chuck's work in statistical mechanics and the second his work in percolation theory, continuum scaling limits, and related topics.Comment: 38 pages (including many references), introduction to Festschrift in honor of C.M. Newma