Frequency estimation : Survey of parametric methods

This paper is a survey of parametric modeling applied to frequency estimation of sinusoidal signals corrupted by an additive noise . A summary of major estimation methods using second or higher order statistics is presented . Discussed techniques include classica l AR modeling (based on Yule-Walker equations) and "High Resolution" methods (Truncated SVD, Root-MUSIC and ESPRIT) . Th e maximum likelihood estimator and Bayesian methods are also under interest . But the selection of the model order in these method s is often a critical one . Thus major model order estimation methods are reviewed . Finally, the efficiency of each method is examined through a simulation example .Le but de cet article est de dresser un panorama des méthodes paramétriques appliquées à l'estimation de fréquences de signaux sinusoïdaux bruités (bruit additif). Nous rappelons les principales méthodes d'estimation basées sur les moments du signal : méthodes classiques déduites des équations de Yule-Walker et méthodes « Haute Résolution » (SVD tronquée, Root-MUSIC et ESPRIT). Nous présentons aussi l'estimateur du maximum de vraisemblance et l'estimation Bayésienne. L'efficacité de ces méthodes étant souvent liée au choix de l'ordre du modèle, nous rappelons les principaux estimateurs de l'ordre. Enfin, une comparaison des méthodes met en évidence les performances de chacune

Functional Principles of Posterior Septal Inputs to the Medial Habenula.

The medial habenula (MHb) is an epithalamic hub contributing to expression and extinction of aversive states by bridging forebrain areas and midbrain monoaminergic centers. Although contradictory information exists regarding their synaptic properties, the physiology of the excitatory inputs to the MHb from the posterior septum remains elusive. Here, combining optogenetics-based mapping with ex vivo and in vivo physiology, we examine the synaptic properties of posterior septal afferents to the MHb and how they influence behavior. We demonstrate that MHb cells receive sparse inputs producing purely glutamatergic responses via calcium-permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), heterotrimeric GluN2A-GluN2B-GluN1 N-methyl-D-aspartate (NMDA) receptors, and inhibitory group II metabotropic glutamate receptors. We describe the complex integration dynamics of these components by MHb cells. Finally, we combine ex vivo data with realistic afferent firing patterns recorded in vivo to demonstrate that efficient optogenetic septal stimulation in the MHb induces anxiolysis and promotes locomotion, contributing long-awaited evidence in favor of the importance of this septo-habenular pathway

Démarche d'analyse spectrale en vue d'une interprétation automatique, application à un signal d'engrenages

Cet article décrit une démarche complète d'analyse spectrale commune à des experts du signal et du domaine concerné (acoustique, mécanique vibratoire) dans le but d'estimer un contenu spectral. L'originalité réside dans le processus de décision qui est fondé sur une confrontation de méthodes (Fourier, Maximum de Vraisemblance, paramétriques, déflation) couplée à une interprétation spectrale. Une pré-analyse consiste à évaluer certaines propriétés du signal (stationnarité, hypothèse gaussienne) et à étudier son autocorrélation. Ensuite, une démarche est construite à partir d'une succession d'analyses spectrales, aboutissant à la détection et à l'identification des différents motifs spectraux. L'interprétation de chaque étape est facilitée par la mise en place de critères objectifs. Enfin des analyses complémentaires sont envisagées (cyclostationnarité, recherche d'harmoniques)

Cyclostationnarités d'ordre 1 et 2 : application à des signaux vibratoires d'engrenages

Le diagnostic précoce des pannes des engrenages fait, en particulier, appel aux caractéristiques cyclostationnaires du signal vibratoire. La cyclostationarité d'un signal se manifeste sur les propriétés moyennes (ordre 1) et sur les propriétés énergétiques (ordre 2) du signal. Nous montrons l'importance de la prise en compte de ces 2 ordres de cyclostationarité pour l'analyse du signal et pour l'estimation de la corrélation spectrale. Nous appliquons cette nouvelle méthode de caractérisation à un signal vibratoire d'engrenage. L'exploitation complète des propriétés cyclostationnaires d'ordre 1 et 2 apporte de nouveaux moyens de diagnostic

Protein Profile Changes during Porcine Oocyte Aging and Effects of Caffeine on Protein Expression Patterns

It has been shown that oocyte aging critically affects reproduction and development. By using proteomic tools, in the present study, changes in protein profiles during porcine oocyte aging and effects of caffeine on oocyte aging were investigated. By comparing control MII oocytes with aging MII oocytes, we identified 23 proteins that were up-regulated and 3 proteins that were down-regulated during the aging process. In caffeine-treated oocytes, 6 proteins were identified as up-regulated and 12 proteins were identified as down-regulated. A total of 38 differentially expressed proteins grouped into 5 regulation patterns were determined to relate to the aging and anti-aging process. By using the Gene Ontology system, we found that numerous functional gene products involved in metabolism, stress response, reactive oxygen species and cell cycle regulation were differentially expressed during the oocyte aging process, and most of these proteins are for the first time reported in our study, including 2 novel proteins. In addition, several proteins were found to be modified during oocyte aging. These data contribute new information that may be useful for future research on cellular aging and for improvement of oocyte quality

A Pro-Cathepsin L Mutant Is a Luminal Substrate for Endoplasmic-Reticulum-Associated Degradation in C. elegans

Endoplasmic-reticulum associated degradation (ERAD) is a major cellular misfolded protein disposal pathway that is well conserved from yeast to mammals. In yeast, a mutant of carboxypeptidase Y (CPY*) was found to be a luminal ER substrate and has served as a useful marker to help identify modifiers of the ERAD pathway. Due to its ease of genetic manipulation and the ability to conduct a genome wide screen for modifiers of molecular pathways, C. elegans has become one of the preferred metazoans for studying cell biological processes, such as ERAD. However, a marker of ERAD activity comparable to CPY* has not been developed for this model system. We describe a mutant of pro-cathepsin L fused to YFP that no longer targets to the lysosome, but is efficiently eliminated by the ERAD pathway. Using this mutant pro-cathepsin L, we found that components of the mammalian ERAD system that participate in the degradation of ER luminal substrates were conserved in C. elegans. This transgenic line will facilitate high-throughput genetic or pharmacological screens for ERAD modifiers using widefield epifluorescence microscopy

Xenopus Meiotic Microtubule-Associated Interactome

In metazoan oocytes the assembly of a microtubule-based spindle depends on the activity of a large number of accessory non-tubulin proteins, many of which remain unknown. In this work we isolated the microtubule-bound proteins from Xenopus eggs. Using mass spectrometry we identified 318 proteins, only 43 of which are known to bind microtubules. To integrate our results, we compiled for the first time a network of the meiotic microtubule-related interactome. The map reveals numerous interactions between spindle microtubules and the newly identified non-tubulin spindle components and highlights proteins absent from the mitotic spindle proteome. To validate newly identified spindle components, we expressed as GFP-fusions nine proteins identified by us and for first time demonstrated that Mgc68500, Loc398535, Nif3l1bp1/THOC7, LSM14A/RAP55A, TSGA14/CEP41, Mgc80361 and Mgc81475 are associated with spindles in egg extracts or in somatic cells. Furthermore, we showed that transfection of HeLa cells with siRNAs, corresponding to the human orthologue of Mgc81475 dramatically perturbs spindle formation in HeLa cells. These results show that our approach to the identification of the Xenopus microtubule-associated proteome yielded bona fide factors with a role in spindle assembly

Effet d'une perturbation sur l'estimation de modèles autorégressifs

In spectral analysis and pattern recognition, especially in speech processing, AutoRegressive (AR) modeling is widely used as a signal parameter estimation tool. In this paper, AR estimation behaviour is studied when applied to signals presenting abrupt changes at an unknown instant of time. A particular abrupt change is studied : the additive change case. This change occurs when, at the instant of change, a signal adds to one which was present before - both signals are independent -. The theoretical sliding window AR parameter expressions are given. We show that blind sliding window AR estimation can lead to a detection tool, allowing additive changes to be detected and distinguished