xDAWN algorithm to enhance evoked potentials: application to brain-computer interface.

International audienceA brain-computer interface (BCI) is a communication system that allows to control a computer or any other device thanks to the brain activity. The BCI described in this paper is based on the P300 speller BCI paradigm introduced by Farwell and Donchin . An unsupervised algorithm is proposed to enhance P300 evoked potentials by estimating spatial filters; the raw EEG signals are then projected into the estimated signal subspace. Data recorded on three subjects were used to evaluate the proposed method. The results, which are presented using a Bayesian linear discriminant analysis classifier , show that the proposed method is efficient and accurate

Perturbation des profils épigénétiques suite à une perte temporaire du maintien de la méthylation de l’ADN dans les cellules embryonnaires

Chez l’embryon précoce, une vague de reprogrammation majeure survient et permet de réinitialiser les profils de méthylation d’ADN de l’ensemble du génome. Lors de cette reprogrammation, les régions différentiellement méthylées (DMRs) (i.e., gènes empreintes) doivent toutefois être protégées de la déméthylation par une action continue de DNMT1 (Méthyltransférase d’ADN 1) pour assurer le développement adéquat de l’épigénome du fœtus. Sachant que l’induction d’une perte temporaire d’expression de Dnmt1 dans un modèle de cellules souches embryonnaires de souris entraîne la perte permanente des patrons de méthylation d’ADN aux régions DMRs et DMR-like, mon projet de recherche vise à comprendre pourquoi ces régions sont incapables de retrouver leurs patrons de méthylation d’ADN initiaux. Notre hypothèse est qu’une adaptation épigénétique (i.e. réarrangement erroné de certaines modifications d’histones) survient aux régions régulatrices de l’expression des gènes (promoteurs et enhancers) et empêche directement ou indirectement le retour au paysage épigénétique initial aux régions affectées. L’objectif du projet est donc de précisément définir comment la perte temporaire de Dnmt1 remodèle le paysage épigénétique aux régions promotrices (H3K4me3, H3K27me3, H3K27ac, H3K4me1, H3K9me3, méthylation d’ADN) et comment les adaptations épigénétiques sont associées avec des changements de l’expression des gènes (ex : gènes des régions DMRs et DMRs-like).In early embryos, a major reprogramming wave occurs and permits to reset DNA methylation profiles genome-wide. During the reprogramming wave, differentially methylated regions (DMRs) (imprinted genes) must be protected from demethylation by the continuous action of DNMT1 (DNA Methyltransferase 1) to ensure the proper development of the foetal epigenome. As the induction of a temporary loss of Dnmt1 expression in a mouse embryonic stem cell model leads to permanent losses of DNA methylation at DMR and DMR-like regions, my project aims to understand why those regions are unable to re-establish their initial DNA methylation patterns. Our hypothesis is that an epigenetic adaptation (erroneous rearrangement of certain histone modifications) occurs at regulatory regions controlling gene expression (promoters and enhancers) and impede directly or indirectly the affected regions to return to their initial epigenetic landscape. The goal of this project is thus to define how the temporary loss of Dnmt1 remodels the epigenetic landscape at promoter regions (H3K4me3, H3K27me3, H3K27ac, H3K4me1, H3K9me3, DNA methylation) and how the epigenetic adaptations are associated with changes in gene expression (ex: genes in DMR and DMR-like regions)

Optimisation de la culture de microalgues pour la production de biodiésel

Affiche présentée dans le cadre du colloque de l'ARC "La gestion de la propriété intellectuelle : courants de pensée et facteurs de succès", lors du 81e Congrès de l'Acfas à l'Université Laval, le 8 mai 2013.Le troisième prix a été décerné à Marc-Olivier Béliveau, Virginie Bertrand-Lehouillier, Jessica Carrier et Joannie Tremblay au concours des Prix étudiants 2012-2013 de l'ARC.Dans l’optique de production de biodiésel, notre projet consistait à évaluer des conditions de culture de microalgues influençant la croissance et la production lipidique. Les souches Chlorella vulgaris, Scenedesmus sp. et Pseudokirchneriella subcapitata ont été cultivées dans différents milieux, dont des eaux usées, en version immobilisée tout comme en suspension. En plus d’avoir comparé les biomasses obtenues, des analyses en contenu lipidique des cultures ont été réalisées par coloration in situ et quantification par fluorescence

Accompagnement dans l’apprentissage de l’argumentation par une équipe pluridisciplinaire : quels effets sur les acteurs?

Dans le cadre du Cursus Master Ingénieur (CMI) de Biologie Santé Environnement (BSE) développé à l’Université de Lorraine en France, une équipe pluridisciplinaire propose aux étudiants de première année de cette formation une Activité de Mise en Situation (AMS). Par groupe de trois ou quatre, ils/elles doivent effectuer une recherche de documentation scientifique sur un sujet de société lié aux sciences pour ensuite élaborer un argumentaire pro- et anti- qui sera présenté oralement. L’équipe pédagogique accompagne les étudiants tout au long du processus, dans l’objectif de favoriser l’intégration et la réussite des nouveaux étudiants. Il s’agit aussi de renforcer des compétences construites au lycée, notamment des compétences informationnelles afin de faciliter l’appropriation de la littéracie universitaire. L’article examine la question des effets de ce dispositif d’accompagnement sur les étudiants et les accompagnants. L’analyse des résultats des étudiants, de leurs réponses à une enquête d’auto-évaluation, de celles des tuteurs lors d’entretiens semi-directifs indique que cette AMS contribue à l’acquisition de compétences et au développement de l’autonomie des étudiants. Les enseignants témoignent d’un changement de posture dans leur rôle d’accompagnant, changement qui transforme aussi leurs pratiques professionnelles dans d’autres cours.Within the framework of a master’s degree in Biological, Health and Environmental Engineering developed at the University of Lorraine in France, a multidisciplinary team offers first year students a Situational Awareness Activity (AMS). In groups of three or four, the students have to carry out scientific documentation research on a societal subject related to science and develop pro and con arguments that are then presented orally. The pedagogical team accompanies the students throughout the process, with the aim of fostering the integration and success of new students. It is also a question of reinforcing the skills built up in high school, in particular informational skills in order to facilitate the appropriation of university literacy. The article examines the effects of this support system on the students and their tutors. The analysis of the students' results, their answers to a self-evaluation survey and those of the tutors during semi-directive interviews indicate that this AMS contributes to the acquisition of skills and the development of students' autonomy. The teachers report a change of stance in their role as tutors, a change that also transforms their professional practices in other courses

Electrospray Ionization and samples complexity in Meta-metabolomics: a biomarker or a suppressed ion?

International audienceIntroductionElectrospray Ionization is one of the most utilized ionization techniques for LC-MS-based metabolomics [1]. However, it presents several drawbacks, e.g. the ion suppression phenomenon, causing ion intensity decrease [2]. The occurrence of the phenomenon is higher if the sample is more complex. Thus, studying samples with different complexities may lead to consider some non-significant molecular features as markers of discrimination. This is due to ion suppression in samples with higher complexity.Material and MethodsThe issue is reported in an environmental context [3,4]. The study is performed on control non-spiked sediment samples and sediments spiked with a complex biopesticide; Bacillus thuringiensis israelensis. Meta-metabolome (endometabolome + xenometabolome) is extracted with QuEChERS method, then analyzed by LC-QToF in order to perform untargeted metabolic profiling, to discover the biomarkers of exposure. This to understand the pesticide impact on spiked sediments compared to control sediments.Results and DiscussionResults revealed several markers with lower intensity in the spiked group. They were co-eluting with multi-charged xenometabolites. Hence, these markers are either less concentrated due to a biological impact, or suppressed by the co-eluted molecules. Thus, to discriminate between biomarkers and suppressed ions, samples are diluted and analyzed. In fact, as dilution decreases the ion suppression, suppressed features are no more significantly discriminant between the two groups of samples.References[1] Bedair et al. 2008. Trends Anal. Chem. 27(3):238–250[2] Antignac et al. 2005. Anal. Chim. Acta. 529(1–2):129–136[3] Patil et al. 2016. Sci. Total Environ. 566–567:552–558[4] Salvia et al. 2018. Environ. Sci. Pollut. Res. 25(30):29841–2984

Radiographic Outcomes of Adult Spinal Deformity Correction : A Critical Analysis of Variability and Failures Across Deformity Patterns

Study Design: Multicenter, prospective, consecutive, surgical case series from the International Spine Study Group. Objectives: To evaluate the effectiveness of surgical treatment in restoring spinopelvic (SP) alignment. Summary of Background Data: Pain and disability in the setting of adult spinal deformity have been correlated with global coronal alignment (GCA), sagittal vertical axis (SVA), pelvic incidence/lumbar lordosis mismatch (PI-LL), and pelvic tilt (PT). One of the main goals of surgery for adult spinal deformity is to correct these parameters to restore harmonious SP alignment. Methods: Inclusion criteria were operative patients (age greater than 18 years) with baseline (BL) and 1-year full-length X-rays. Thoracic and thoracolumbar Cobb angle and previous mentioned parameters were calculated. Each parameter at BL and 1 year was categorized as either pathological or normal. Pathologic limits were: Cobb greater than 30 , GCA greater than 40 mm, SVA greater than 40 mm, PI-LL greater than 10 , and PT greater than 20 . According to thresholds, corrected or worsened alignment groups of patients were identified and overall radiographic effectiveness of procedure was evaluated by combining the results from the coronal and sagittal planes. Fondation Paristech, ISS

THz Magneto-electric atomic rotations in the chiral compound Ba3_3NbFe3_3Si2_2O14_{14}

We have determined the terahertz spectrum of the chiral langasite Ba$_3$NbFe$_3$Si$_2$O$_{14}$ by means of synchrotron-radiation measurements. Two excitations are revealed that are shown to have a different nature. The first one, purely magnetic, is observed at low temperature in the magnetically ordered phase and is assigned to a magnon. The second one persits far into the paramagnetic phase and exhibits both an electric and a magnetic activity at slightly different energies. This magnetoelectric excitation is interpreted in terms of atomic rotations and requires a helical electric polarization