Convergence des filtres adaptatifs dans le contexte alphabet fini

Dans ce papier, nous étudions la convergence en moyenne quadratique des filtres adaptatifs, pilotés par l'algorithme du gradient stochastique (GS). Le contexte où l'entrée appartient à un alphabet fini est considéré ; il correspond au contexte réel de transmission numérique. Nous proposons une approche mathématique adaptée à ce contexte, qui permet une analyse simple et rigoureuse, de convergence et ce, sans passer par des hypothèses simplificatrices classiques de type "indépendance" des vecteurs observations

Influence de la puissance de l'entrée sur la capacité de poursuite des filtres adaptatifs

Une analyse de l'influence de la puissance de l'entrée sur la capacité de poursuite de l'algorithme du gradient stochastique (GS) est présentée. Cet algorithme est utilisé en identification d'un système non stationnaire dont les variations sont modélisées par une promenade aléatoire. Nous montrons l'influence contradictoire de la puissance de l'entrée sur la déviation quadratique moyenne et l'erreur quadratique moyenne résiduelle optimales. Lorsque deux non stationnarités sont combinées, celle de l'entrée du système à identifier et celle du système, nous montrons l'apport relatif de certains algorithmes normalisés pour une identification robuste face aux variations de la puissance de l'entrée

Theoretical Spectroscopic Study of Two Ketones of Atmospheric Interest: Methyl Glyoxal (CH3COCHO) and Methyl Vinyl Ketone (CH3COCH═CH2)

Two ketones of atmospheric interest, methyl glyoxal and methyl vinyl ketone, are studied using explicitly correlated coupled cluster theory and core-valence correlationconsistent basis sets. The work focuses on the far-infrared region. At the employed level of theory, the rotational constants can be determined to within a few megahertz of the experimental data. Both molecules present two conformers, trans/cis and antiperiplanar (Ap)/ synperiplanar (Sp), respectively. trans-Methyl glyoxal and Ap-methyl vinyl ketone are the preferred structures. cis-Methyl glyoxal is a secondary minimum of very low stability, which justifies the unavailability of experimental data in this form. In methyl vinyl ketone, the two conformers are almost isoenergetic, but the interconversion implies a relatively high torsional barrier of 1798 cm-1. A very low methyl torsional barrier was estimated for trans-methyl glyoxal (V3 = 273.6 cm-1). Barriers of 429.6 and 380.7 cm-1 were computed for Ap- and Sp-methyl vinyl ketone. Vibrational second-order perturbation theory was applied to determine the rovibrational parameters. The far-infrared region was explored using a variational procedure of reduced dimensionality. For trans-methyl glyoxal, the ground vibrational state was estimated to split by 0.067 cm-1, and the two low excited energy levels (1 0) and (0 1) were found to lie at 89.588 cm-1/88.683 cm-1 (A2/E) and 124.636 cm-1/123.785 cm-1 (A2/E). For Ap- and Sp-methyl vinyl ketone, the ground vibrational state splittings were estimated to be 0.008 and 0.017 cm-1, respectively.This project received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Marie Skłodowska-Curie Grant Agreement 872081. The authors acknowledge the National Plan for Science, Technology and Innovation (MAARIFAH), King Abdulaziz City for Science and Technology, Kingdom of Saudi Arabia (Award 0061-001- 01-17-2) and the Ministerio de Ciencia, Innovación y Universidades of Spain (Grants EIN2019-103072, PID2020- 112887GB-I00, PID2019-104002GB-C21, and ERDF A Way of Making Europe, by the European Union Next Generation EU/ PRTR). The authors acknowledge CTI (CSIC) and CESGA and the Red Española de Computación for Grants AECT-2020- 2-0008 and RES-AECT-2020-3-0011 for computing facilities

Central nervous system infection following vertical transmission of Coxsackievirus B4 in mice

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Coxsackie B viruses (CV-B) are important pathogens associated with several central nervous system (CNS) disorders. CV-B are mainly transmitted by the faecal-oral route, but there is also evidence for vertical transmission. The outcome of in utero CV-B infections on offspring's CNS is poorly explored. The aim of this study was to investigate vertical transmission of CV-B to the CNS. For this purpose, pregnant Swiss albino mice were intraperitoneally inoculated with CV-B4 E2 at gestational days 10G or 17G. Different CNS compartments were collected and analyzed for virus infection and histopathological changes. Using plaque assays, we demonstrated CV-B4 E2 vertical transmission to offspring's CNS. Viral RNA persisted in the CNS up to 60 days after birth, as evidenced by a sensitive semi-nested(sn) reverse transcripton(RT)-PCR method. This was despite infectious particles becoming undetectable at later time points. Persistence was associated with inflammatory lesions, lymphocyte infiltration and viral dsRNA detected by immunohistochemistry. Offspring born to dams mock- or virus-infected at day 17G were challenged by the same virus at day 21 after birth (-+ and ++ groups, respectively). Sn-RT-PCR and histology results compared between both ++ and -+ groups, show that in utero infection did not enhance CNS infection during challenge of the offspring with the same virus.This work was supported by Ministère de l’Enseignement Supérieur et de la Recherche Scientifique, (LR99ES27), Tunisia, and Ministère de l’Education Nationale de la Recherche et de la Technologie, Université Lille 2 CHRU Lille (UPRES EA3610), France. Financial support for S.J.R has come from the European Commission 7th Framework Programme PEVNET [FP7/2007-2013] under grant agreement number 261441 and a Juvenile Diabetes Research Foundation (JDRF) Career Development Award (5-CDA-2014-221-A-N). Habib JMII was supported by grants from Ministère de l’Enseignement Supérieur et de la Recherche Scientifique

Detecting hazardous situations faced by presbycusic pedestrians in cities: an audio-texture approach

Within a universal context of an aging population along with an increasing consciousness regarding senior pedestrians’ safe access to the city, we examine the case of seniors affected by presbycusis, specifically their altered perceptions of the urban sonic ambiances during their daily journeys through the city. In this study, we present the urban configurations in which alarming situations were encountered by senior pedestrians suffering from presbycusis. We then construct an experimental protocol correlating collected data including audio signals, commented walks and physiological measurements of stress level generated while crossing the urban configurations previously identified. This cross-analysis process may provide urban planners with two-dimensional graphic representations intended to detect hazardous situations in order to anticipate them and minimize their effects.Dans un contexte mondial de vieillissement de la population, les personnes âgées sont très vulnérables en milieu urbain, particulièrement lorsqu’elles souffrent de presbyacousie qui altère leur perception de l’environnement sonore. Dans cette étude, nous identifions les configurations urbaines dans lesquelles des situations de danger rencontrées par ces personnes apparaissent. Nous construisons ensuite un protocole expérimental corrélant des données issues de parcours commentés, des mesures physiologiques du niveau de stress engendré lors de la traversée des configurations précédemment identifiées et un traitement physique du signal sonore enregistré. Ce traitement se décline sous la forme de plusieurs représentations graphiques qui permettraient de détecter ces situations de danger et de fournir ainsi aux décideurs urbains un outil graphique prédictif

Calcul de la probabilité d'erreur pour une chaîne de tatouage audionumérique à bruit non gaussien

- La chaîne de tatouage audionumérique étudiée peut être vue comme une chaîne de communications numériques particulière du fait du caractère non gaussien du bruit additif d'une part et du faible rapport signal à bruit variable par fenêtre d'autre part. L'objectif de cette étude est de mener un calcul théorique de la probabilité d'erreur que l'on est en mesure d'atteindre, en tenant compte de ces spécificités. Cette étude théorique est un préalable à un choix adéquat d'un système de codage canal dans un contexte de tatouage audio

Reconstruction 3D de sténoses par modélisation markovienne à partir de plus de deux images d'angiographie rotative par rayons X

- Dans cette contribution, nous proposons une méthode de reconstruction tridimensionnelle (3D) locale de sténoses à partir de plus de deux images ou projections extraites d'une séquence d'images d'angiographie rotative par rayons X. Cette méthode utilise une modélisation markovienne dont l'énergie comprend un terme décrivant l'a priori sur la structure vasculaire à reconstruire ainsi qu'un terme d'ajustement aux projections. Cette modélisation est une généralisation de celle introduite dans [1]. En effet, l'énergie d'ajustement est modifiée afin de prendre en compte un nombre de projections supérieur à deux. Cette généralisation augmente le nombre de contraintes ce qui diminue le nombre de minima globaux de l'énergie markovienne. Les simulations réalisées dans ce travail montre que cela améliore sensiblement la qualité de la reconstruction dans le cas de présence de sténoses de formes complexes

Effect of Coxsackievirus B4 Infection on the Thymus: Elucidating Its Role in the Pathogenesis of Type 1 Diabetes

peer reviewedThe thymus gland is a primary lymphoid organ for T-cell development. Various viral infections can result in disturbance of thymic functions. Medullary thymic epithelial cells (mTECs) are important for the negative selection of self-reactive T-cells to ensure central tolerance. Insulin-like growth factor 2 (IGF2) is the dominant self-peptide of the insulin family expressed in mTECs and plays a crucial role in the intra-thymic programing of central tolerance to insulin-secreting islet β-cells. Coxsackievirus B4 (CVB4) can infect and persist in the thymus of humans and mice, thus hampering the T-cell maturation and differentiation process. The modulation of IGF2 expression and protein synthesis during a CVB4 infection has been observed in vitro and in vivo in mouse models. The effect of CVB4 infections on human and mouse fetal thymus has been studied in vitro. Moreover, following the inoculation of CVB4 in pregnant mice, the thymic function in the fetus and offspring was disturbed. A defect in the intra-thymic expression of self-peptides by mTECs may be triggered by CVB4. The effects of viral infections, especially CVB4 infection, on thymic cells and functions and their possible role in the pathogenesis of type 1 diabetes (T1D) are presented

How does thymus infection by coxsackievirus contribute to the pathogenesis of type 1 diabetes?

Through synthesis and presentation of neuroendocrine self-antigens by major histocom- patibility complex proteins, thymic epithelial cells (TECs) play a crucial role in programing central immune self-tolerance to neuroendocrine functions. Insulin-like growth factor- 2 (IGF-2) is the dominant gene/polypeptide of the insulin family that is expressed in TECs from different animal species and humans. Igf2 transcription is defective in the thymus of diabetes-prone bio-breeding rats, and tolerance to insulin is severely decreased in Igf2−/− mice. For more than 15 years now, our group is investigating the hypothesis that, besides a pancreotropic action, infection by coxsackievirus B4 (CV- B4) could implicate the thymus as well, and interfere with the intrathymic programing of central tolerance to the insulin family and secondarily to insulin-secreting islet β cells. In this perspective, we have demonstrated that a productive infection of the thymus occurs after oral CV-B4 inoculation of mice. Moreover, our most recent data have demonstrated that CV-B4 infection of a murine medullary (m) TEC line induces a significant decrease in Igf2 expression and IGF-2 production. In these conditions, Igf1 expression was much less affected by CV-B4 infection, while Ins2 transcription was not detected in this cell line. Through the inhibition of Igf2 expression in TECs, CV-B4 infection could lead to a breakdown of central immune tolerance to the insulin family and promote an autoimmune response against insulin-secreting islet β cells. Our major research objective now is to understand the molecular mechanisms by which CV-B4 infection of TECs leads to a major decrease in Igf2 expression in these cells.Euro-Thymaid