Exact Distribution of the Local Score for Markovian Sequences,

International audienceWe provide the exact distribution of the local score in random sequences in several models. We will first consider a Markov model on the score sequence, and then on the letter sequence. The exact P-value of the local score obtained with both models are compared thanks to several datasets. they are elso comparde with previous results using the independent model

Quand des lycéens contribuent à Wikipédia : quelles évolutions de leurs connaissances informationnelles ?

International audienceYoung people frequently use Wikipedia. However their knowledge of the editorial process of this encyclopedia and its technical device is limited. This might be problematic for the evaluation of information. This article aims to present how high school students acquire knowledge about Wikipedia by participating in a Wikiconcours. This educational innovation organized by the CRDP of the Academy of Toulouse and Wikimedia France consisted in the creation or improvement of encyclopedia articles by students. We examine the types of relationships between teachers, students and the wikipedian community as well as the transferability of information skills.Les jeunes utilisent fréquemment Wikipédia. Toutefois, leurs connaissances sur le modèle éditorial de cette encyclopédie et le dispositif technique sur lequel elle repose sont limitées, ce qui peut s’avérer problématique pour l’évaluation de ses articles. L’objectif de cet article est de rendre compte des évolutions des connaissances sur Wikipédia chez des lycéens ayant participé à un Wikiconcours. Cette innovation pédagogique organisée par le CRDP de l’académie de Toulouse et Wikimédia France a consisté en la création ou l’amélioration d’articles de l’encyclopédie par les élèves. Nos observations nous conduisent à analyser les relations entre enseignants, élèves et communauté wikipédienne ainsi que les possibilités de transfert des connaissances informationnelles dans le cadre de cette pédagogie du projet

Distribution exacte du score local, cas Markovien

National audienceSoit X = (Xk)k≥1 une suite de variables à valeurs dans {−v, ..., 0, ...,+u}. On définit le score local d'une séquence par Hn = max1≤i≤j≤n j k=iXk . Le score local est utilisé notamment dans l'analyse des séquences biologiques afin de mettre en évidence des régions de séquences ayant des propriétés biologiques intéressantes. La signification statistique des scores locaux calculés permet alors de mettre en évidence ce qui est réellement intéressant et il est donc nécessaire de connaître la distribution du score local. Nous établissons ici la loi exacte du score local dans le cas où la suite des Xi est une chaîne de Markov d'ordre 1

Unbiased risk estimation method for covariance estimation

We consider a model selection estimator of the covariance of a random process. Using the Unbiased Risk Estimation (URE) method, we build an estimator of the risk which allows to select an estimator in a collection of model. Then, we present an oracle inequality which ensures that the risk of the selected estimator is close to the risk of the oracle. Simulations show the efficiency of this methodology

New approximate P-value of gapped local sequence alignments,

International audienceWe propose a new method to approximate the signi cativity of gapped local sequence alignments. We focus on short sequences for which standard methods are known to be less accurate since they have been developed under asymptotics. Our approach combines an approximate distribution of ungapped local score of two sequences and a special scoring scheme that allows the insertion of gaps. For a positive integer h, the scoring scheme is de ned on h-tuples of the components of the sequences and corresponds to the gapped global score. The in uence of h and the accuracy of the p-value are numerically studied

Hygrothermal behaviour of hemp concrete; experimental evidences and modelling

This paper presents experimental hygrothermal data of an hemp concrete wall of dimensions 0.9×0.9×0.1 [m3]. The wall is instrumented with sensors to monitor temperature, relative humidity at the middle of the wall and incoming heat flows at the external surfaces. It is placed in a double climatic chamber that allows the regulation of temperature and relative humidity on each side of the wall, independently to each other. The experimental results leads to a clear identification of the coupling between the variation of the relative humidity inside the wall and its temperature. The validity of the commonly adopted assumptions for hygrothermal simulation are finally analyzed in the light of these experimental results. The material parameters used for the simulations are measured separately on decimetric samples of the same hemp concrete, which comes from the same mix and with the same apparent density

Elements related to the largest complete excursion of a reflected BM stopped at a fixed time. Application to local score.

International audienceElements related to the largest complete excursion of a reflected BM stopped at a fixed time. Application to local score