Hidden semi-Markov models to segment reading phases from eye movements

Our objective is to analyze scanpaths acquired through participants achieving a reading task aiming at answering a binary question: Is the text related or not to some given target topic? We propose a data-driven method based on hidden semi-Markov chains to segment scanpaths into phases deduced from the model states, which are shown to represent different cognitive strategies: normal reading, fast reading, information search, and slow confirmation. These phases were confirmed using different external covariates, among which semantic information extracted from texts. Analyses highlighted some strong preference of specific participants for specific strategies and more globally, large individual variability in eye-movement characteristics, as accounted for by random effects. As a perspective, the possibility of improving reading models by accounting for possible heterogeneity sources during reading is discussed

Experimental evidence of hot carriers solar cell operation in multi-quantum wells heterostructures

International audienceWe investigated a semiconductor heterostructure based on InGaAsP multi quantum wells (QWs) using optical characterizations and demonstrate its potential to work as a hot carrier cell absorber. By analyzing photoluminescence spectra, the quasi Fermi level splitting Dl and the carrier temperature are quantitatively measured as a function of the excitation power. Moreover, both thermodynamics values are measured at the QWs and the barrier emission energy. High values of Dl are found for both transition, and high carrier temperature values in the QWs. Remarkably, the quasi Fermi level splitting measured at the barrier energy exceeds the absorption threshold of the QWs. This indicates a working condition beyond the classical Shockley-Queisser limit

Data Science : une formation internationale de niveau Master en science des données

International audienceWe present the international training program in Data Science at master 2 level. This program is supported by both Grenoble Alpes University and Grenoble INP. In this article, we elaborate on the specific features of the program, its strategic position, operating and historical features, the detailed contents of courses and perspectives of evolution.Nous présentons la formation internationale de niveau master 2 en Data Science de l'Université Grenoble Alpes et de Grenoble INP : spécificités et positionnement de la formation, fonctionnement et aspects historiques de sa création, programme de cours détaillé et perspectives d'évolution

Cryptococcosis with ocular and central nervous system involvement in a 3‐year‐old dog

To date, cryptococcosis remains sporadic in Europe, and this is a case of canine cryptococcosis with ocular and CNS involvement in continental Europe with identification of the organism on cerebral spinal fluid (CSF) cytology and description of the clinical and MRI features, and outcome

West Nile Virus in Horses, sub-Saharan Africa

To evaluate the presence and extension of West Nile virus where French soldiers are stationed in Africa, specific antibody prevalence was determined by using ELISA and Western blot. Among 245 horses living in close proximity to the soldiers, seroprevalence was particularly high in Chad (97%) and Senegal (92%)

Assessment of various initialization strategies for the Expectation-Maximization algorithm for Hidden Semi-Markov Models with multiple categorical sequences

National audienceIn this study, we propose a method called sequence breaking framework to search high local maximum of the likelihood by providing starting values based on the observations for the Expectation-Maximization algorithm, for Hidden semi-Markov model parameter estimation. The method is shown to be efficient on several datasets with multiple categorical sequences

Modèles de semi-Markov cachés pour la segmentation de trajectoires oculométriques en phases de lecture

Textual information search is not a homogeneous process in time, neither from a cognitive perspective nor in terms ofeye-movement patterns, as shown in previous studies. Our objective is to analyze eye-tracking signals acquired throughparticipants achieving a reading task aiming at answering a binary question: Is the text related or not to some given targettopic? This activity is expected to involve several phases with contrasted oculometric characteristics, such as normalreading, scanning, careful reading, associated with different cognitive strategies, such as creation and rejection ofhypotheses, confirmation and decision. To model such phases, we propose an analytical data-driven method based onhidden semi-Markov chains, whose latent states represent different dynamics in eye movements.Four interpretable phases were highlighted: normal reading, speed reading, information search and slow confirmation.This interpretation was derived using model parameters and scanpath segmentations. It was then confirmed usingdifferent external covariates, among which semantic information extracted from texts. Analyses highlighted a gooddiscrimination of reading speeds by phases, some contrasted use of phases depending on the degree of relationshipbetween text semantic contents and target topics, and a strong preference of specific participants for specific strategies.As another output of our analyses, the individual variability in all eye-movement characteristics was assessed to be highand thus had to be taken into account, particularly trough mixed-effects models.As a perspective, the possibility of improving reading models by accounting for possible heterogeneity sources duringreading was discussed. We highlighted how analysing other sources of information regarding the cognitive processes atstake, such as EEG recordings, could benefit from the segmentation induced by our approach.La recherche d’information textuelle n’est pas un processus homogène dans le temps, que ce soit d’unpoint de vue cognitif ou de celui des mouvements des yeux, ainsi que l’ont montré des études précédentes. Notreobjectif est d’analyser des signaux oculométriques acquis lors de tâches où les participant.e.s doivent répondre à unequestion binaire : est-ce que le texte est lié ou non à un thème cible donné ? Nous nous attendons à ce que cetteactivité mette en jeu diverses phases avec des caractéristiques oculométriques contrastées, telle que la lecturenormale, rapide, de confirmation et de décision. Pour mettre en évidence des différentes phases, nous proposons uneméthode basée sur l’analyse de données fondée sur des modèles semi-markoviens cachés, dont les états latentsreprésentent différentes dynamiques relatives aux mouvements des yeux. Quatre phases interprétables ont étémises en évidence : lecture normale, lecture rapide, recherche d’information et confirmation lente. Leur interprétationdécoule des paramètres du modèle et de la segmentation des traces oculométriques.En perspective, nous discutons des possibilités offertes par cette approche pour améliorer des modèles de lecture enprenant en compte de potentiels modes de lecture hétérogènes mobilisés dans ce type de tâche. Nous mettons enévidence comment l’analyse d’autres sources d’information relatives aux processus cognitifs mis en jeu, telles quedes enregistrements EEG, pourraient bénéficier de la segmentation induite par notre approche

Theoretical study of optical properties of anti phase domains in GaP

International audienceIII-V/Si heterostructures are currently investigated for silicon photonics and solar energy conversion. In particular, dilute nitride alloy GaAsPN grown on a GaP/Si platform exhibits lattice match with Si and an optimal band gap configuration for tandem solar cell devices. However, monolithic "coherent" growth of the GaP thin layer on Si suffers from the nucleation of extended structural defects, which can hamper device operation as well as the GaP/Si interface level and through their propagation inside the overall heterostructure. However, the effect of such structural defects on optical and transport properties is actually not well understood in details. In this letter, we investigate the anti phase domains defect (also called inversion domains) by means of ab initio calculations giving insights into the alteration of optical and transport properties of GaP due to the defective GaP/Si interface

Synthesis of Cyclen-Functionalized Ethenylene-Based Periodic Mesoporous Organosilica Nanoparticles and Metal-Ion Adsorption Studies

The preparation of two cyclens both possessing two triethoxysilyl groups through click chemistry is described. These two cyclens were incorporated into bis(triethoxysilyl)ethenylene-based periodic mesoporous organosilica nanoparticles (PMO NPs) at different proportions of bis(triethoxysilyl)ethenylene/cyclens (90/10, 75/25). The obtained nanorods were analyzed with different techniques and showed high specific surface areas at low proportion of cyclens. The nanorods containing free amino groups of cyclen were then used for Ni(II) and Co(II) removal from model solutions. The kinetics and isotherms of adsorption of Ni(II) and Co(II) were determined, and the materials showed high uptake of metals (up to 3.9 mmol . g(-1)). They demonstrated pronounced selectivity in separation of rare earth elements from late transition metals, e. g. Ni(II) and Co(II) by adsorption and even more so by controlled desorption