Discrimination de courbes par régression inverse fonctionnelle

19 pagesNational audienceLes méthodes de régression inverse telles que la SIR (Li,1991) ont été développées dans le domaine de la régression multivariée pour éviter le célèbre fléau de la dimension. Elles ont été récemment étendues aux données fonctionnelles. Plusieurs approches ont été proposées et nous présentons ici un article de synthèse et de comparaison en abordant le cas où la variable réponse est un vecteur d'indicatrice d'appartenance à des classes. Nous montrons qu'alors la régression inverse conduit à une méthode de discrimination dont la pertinence est établie sur des données réelles et simulées

Wavelet Coefficients of Levy Process

International audienceCet article présente une expression de la fonction caractéristique des coefficients de décomposition en ondelettes d'un processus de Levy. Le cas particulier de l'ondelette de Haar et d'un processus entrelacé est traité plus en détail

Multivariate Functional Data Clusterization by PCA in Sobolev Space Using Wavelets

International audienceNous présentons une méthode basée sur la classification en espace fonctionnel appliquée aux trajectoires avion. La particularité des données est de se présenter comme des fonctions deux fois continuement différentiable par morceaux, l'information discriminante se situant des les sauts. L'utilisation d'une décomposition en ondelettes permet une implémentation simple en espace de Sobolev et permet de séparer correctement des trajectoires présentant des points de branchement

h-tuple Approach to Evaluate Statistical Significance of Biological Sequence Comparison with Gaps,

International audienceWe propose an approximate distribution for the gapped local score of a two sequence comparison. Our method stands on combining an adapted scoring scheme that includes the gaps and an approximate distribution of the ungapped local score of two independent sequences of i.i.d. random variables. The new scoring scheme is defined on h-tuples of the sequences, using the gapped global score. The influence of h and the accuracy of the p-value are numerically studied and compared with obtained p-value of BLAST. The numerical experiments emphasize that our approximate p-values outperform the BLAST ones, particularly for both simulated and real short sequences

Impact of three ampicillin dosage regimens on selection of ampicillin resistance in Enterobacteriaceae and excretion of blaTEM genes in swine feces

The aim of this study was to assess the impact of three ampicillin dosage regimens on ampicillin resistance among Enterobacteriaceae recovered from swine feces using phenotypic and genotypic approaches. Phenotypically, ampicillin resistance was determined from the percentage of resistant Enterobacteriaceae and MICs of E. coli isolates. The pool of ampicillin resistance genes was also monitored by quantification of blaTEM genes, which code for the most frequently produced β-lactamases in Gram-negative bacteria, using a newly-developed real-time PCR assay. Ampicillin was administered intramuscularly and by oral route to fed or fasted pigs for 7 days at 20 mg/kg. The average percentage of resistant Enterobacteriaceae before treatment was between 2.5% and 12% and blaTEM genes quantities were below 107 copies/g of feces. By days four and seven, the percentage of resistant Enterobacteriaceae exceeded 50% in all treated groups, with some highly resistant strains (MIC>256µg/mL). In the control group, blaTEM genes quantities fluctuated between 104 - 106 copies/g of feces, whereas they fluctuated between 106-108 and 107-109 copies/g of feces for intramuscular and oral routes, respectively. Whereas phenotypic evaluations did not discriminate between the three ampicillin dosage regimens, blaTEM genes quantification was able to differentiate between the effects of two routes of ampicillin administration. Our results suggest that fecal blaTEM genes quantification provides a sensitive tool to evaluate the impact of ampicillin administration on the selection of ampicillin resistance in the digestive microflora and its dissemination in the environment

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

Structure et dynamique de neuropeptides liés à leur récepteur

International audienc

Dietary plasma proteins attenuate the innate immunity response in a mouse model of acute lung injury

We examined whether oral plasma protein supplements affect the innate immune response in a model of acute lung inflammation. Mice were fed diets supplemented with 8% spray-dried plasma (SDP) or 2% plasma Ig concentrate (IC) from day 19 (weaning) until day 34. The mice were challenged with intranasal lipopolysaccharide (LPS) at day 33 (and killed 24 h later for cytokine and leucocyte analyses) or at day 34 (and killed 6 h later for cytokine determinations). In bronchoalveolar lavage fluid (BALF), LPS increased the number of leucocytes by twenty-sevenfold, an effect that was partly prevented by both SDP and IC, and by twentyfold the percentage of activated monocytes, which was partly prevented by SDP. In the lung tissue, LPS increased the infiltrated leucocytes, and this effect was prevented in part by SDP. In unchallenged mice, both SDP and IC diets reduced the percentage of resident neutrophils and monocytes (P,0·05). In the blood, both SDP and IC completely prevented LPS-dependent monocyte activation (CD14þ; P,0·05). LPS dramatically increased the concentration of cytokines (TNF-a, IL-1a, IL-6, granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor) and chemokines (CXCL1, CCL2, CCL3 and CCL4) in BALF. The acute response of cytokine production was reduced by 20-80% by both SDP and IC. For chemokines, plasma supplements had no effect on LPS-induced CXCL1 expression but significantly reduced CCL2, CCL3 and CCL4 production (P,0·05). The results support the view that dietary plasma proteins can be used to attenuate endotoxin-associated lung inflammation