NCube/papyrus huggingface dataset:
Development of auditory repetition effects with age : evidence from EEG time-frequency analysis

The repeated presentation of unfamiliar sounds leads to repetition effects comprising repetition suppression (RS) and enhancement (RE) of neural activity. These phenomena reflect mechanisms involved in perceptual learning and are associated with a decrease or increase in EEG spectral powers. The objective of this Master’s thesis is to provide a developmental perspective of the cortical activity underlying auditory perceptual learning. EEG was recorded in 101 healthy participants ranging from 3 to 40 years during an auditory paradigm comprising 30 pseudowords repeated six times each. EEG time-frequency spectral power was calculated for each presentation and was compared to quantify repetition effects. Linear mixed model analysis revealed that some repetition effects occurred across ages and others varied with age in specific frequency bands. More precisely, RS and RE were found across ages in lower theta and gamma frequency bands respectively between the first and all subsequent pseudoword presentations. Developmental effects were seen in the RS observed in the higher theta/low alpha band and in the later occurring RE in the lower theta band. These results show that processes involved in auditory perceptual learning, such as RS and RE, are modulated by maturation. Further, repetition effects reflect different levels of stimulus processing and these levels seem to develop independently. More research is required to identify the exact functional roles of auditory repetitions effects on cognitive development.

Keyphrases: EEG, repetition suppression, EEG spectral power, Brain development, Time-frequency analysis
Traitement de stimuli sexuels visuels statiques par l’insula en EEG intracrânien : une étude de potentiels évoqués

The insula is a bilateral cortical structure with many anatomical and functional connections, and found active in cognitive, somatosensory and emotional processing. Many brain imaging studies found insular activity during sexual response, notably when visual sexual stimuli are presented. While hypotheses have emerged to explain this activity, they are all tainted by the fMRI limitations of relatively low temporal resolution as well as being an indirect measure of brain electrical activity. The present project seeks to clarify insular activity in this context with the use of intracranial EEG, which has a better temporal resolution and equivalent spatial resolution compared to fMRI. Four participants implanted with intracranial electrodes in the insula passively watched sexual and neutral pictures. ERP curves were computed for both types of stimuli, and statistically compared via non-parametric permutation tests. It was found that the insula reacts differently for sexual stimuli compared to neutral stimuli. More specifically, the insula produces a positive deflection peaking between 300 and 400 ms, followed by a later component (peaking around 800 ms) and constant positive activity (> 1,000 ms). These results suggest that the insula generates an affective P300 as well as a late positive potential, further suggesting a role in attentional maintenance to sexual stimuli, probably for their saliency. Furthermore, it is hypothesized that the insula is especially linked, in the context of sexual stimulation, to attention of somatosensory processing.

Keyphrases: Insula, ERP, P300, LPP, sexual stimuli, saliency, intracranial EEG
L'influence d'Internet, des téléphones intelligents et des GPS sur le système de mémoire hippocampique

When people navigate in an environment, they adopt preferentially different navigational strategies that depend on distinct parts of the brain : the hippocampus or the caudate nucleus. Research has shown that the grey matter in the caudate nucleus shares an inverse relationship with the grey matter in the hippocampus. Several studies have also suggested that the overuse of technology like video games, the Internet, smartphones, can have negative impacts on the hippocampus. We assumed that an increased dependence on these technologies, possibly affecting the hippocampus - causing a decrease in its use -, may lead to an overuse of the caudate nucleus. In that respect, we hypothesize that people who utilize these forms of technology more often, will tend to utilize more caudate nucleus-dependent navigational strategy. To answer this question, we measured 38 participant’s level of the Internet, GPS and smartphone usage. Then, participants were tested using the 4 on 8 virtual maze, which determines the navigational strategy a person adopts. To ensure that sleep and education did not influence the results, the test of non-verbal intelligence, TONI-4, as well as the Pittsburgh sleep quality index were also passed. Consequently, we found that heavy users of technology are not significantly more likely than light users to deploy a response navigational strategy. Under these conditions, it appears that technology has no effect on navigational strategies and therefore, possibly on related structures. Lower grey matter within the hippocampus increases the risks of developing neurodegenerative disorders and technology now plays a very important role in our societies. Understanding what behaviours tend to affect the integrity of this system could lead to the development of better preventive measures for future generations, justifying studies like this one.

Keyphrases: Technologies, Mémoire spatiale, Virtual maze, Spatial memory, Caudate nucleus, hippocampus
Influence du climat social de l’équipe d’éducateurs sur le recours aux mesures de contention et d’isolement : une étude longitudinale en centre de réadaptation pour jeunes

Background Aggressive behaviors are part of daily life in residential treatment centers (RTCs) given the problems of youths residing there. Among the interventions that can be used are restraint and seclusion. Although studies on the topic are scarce, factors related to the environment, child, and educator have been associated with these interventions. Although an association has been shown between the team’s social climate and recourse to restraint and seclusion in psychiatric settings, it has yet to be studied in RTCs. Objectives The first objective of this paper was to assess the extent to which the social climate influences the use of restraint and seclusion in RTCs for youth. The second objective was to observe how each dimension of social climate influences recourse to restraint and seclusion.  Methods A sample of 198 RTC educators completed a questionnaire on their team’s social climate at three times. Crossed-lagged analyses were performed to assess the association between different dimensions of social climate and use of restraint and seclusion over time. Results The communication and openness of team members as well as their centration on common objectives and planification were associated with the use of these measures. The negative character of the climate was not associated with the use of restraint and seclusion.  Implications The results of the current study suggest that promoting the individual initiative of interventions adapted to the needs of the youth and reducing standard interventions could decrease the influence of the social climate on the use of restraint and seclusion in RTCs.

Keyphrases: residential care, youth, restraint, seclusion, social climate, careworker
Évaluation de la mise en oeuvre et des processus du programme Blues, un programme de prévention indiquée de la dépression, dans trois écoles secondaires montréalaises

Several interventions have been developed to help adolescents who struggle with mental health difficulties, but few of these interventions have been evaluated in real-world practice. The present study is embedded in the larger evaluation of the Blues program, a group-based cognitive-behavioral program aimed at preventing depression in at-risk adolescents, that was conducted in 2016 in the real-world context of 3 Montreal high schools. The first goal of this study was to describe the implementation of the program using four criteria : integrity, dosage, animation quality and participants’ responsiveness (Dane & Schneider, 1998). The second goal was to identify factors that facilitated or hindered implementation, as well as factors that could have facilitated implementation. The third and last goal of the study was to determine whether participants’ responsiveness, defined in terms of attendance to sessions and homework completion, was linked to changes in depressive symptoms at posttest.  Data were collected in relation to 5 Blues groups implemented in three secondary schools. All meetings were recorded and subsequently coded to assess fidelity. Interviews were conducted with participants (n = 37) and facilitators (n = 6) to identify facilitating factors and obstacles.   Results showed a successful implementation of the program, except with regards to homework completion and make-up sessions. Several factors that helped or hindered the implementation were identified from the interviews, including the lack of time, the program’s usefulness and it’s user-friendly manual. Results indicate a potential association between greater attendance and lower depressive symptoms at posttest, suggesting that dosage may be a necessary component of the program. Recommandations were made for the future, such as revising the program manual, implementing the program in the fall, rather than in the winter or spring, and optimizing the Blues website used to complete homework.

Keyphrases: Prévention, Implementation, Evaluation, Effectiveness, Cognitive behavioral, Depression
Exploration des motifs justifiant le recours aux mesures de contention et d'isolement en centre de réadaptation pour jeunes au Québec: la perception des intervenants

Restraints and seclusions (R&S) in youth residential treatment centers (RTCs) should be used as a last resort to control violent and aggressive behavior. Their use has consequences; it can lead to physical and psychological iatrogenic effects for both youth and educators. There are no empirical evidences that suggest that they help develop self-regulation strategies or prosocial behaviors. Even if they are legislated by laws, recourse to R&S seems to be highly influenced by situational factors. Objective. Explore the reasons involved in the decisions-making process leading to R&S application in RTCs, according to practitioner’s perceptions. Methodology. A qualitative thematic analysis explanatory design was used. Empirical saturation was reached following the analysis of 628 reports of R&S, from 21 RTCs units for youths over the course of fourteen months. Results. Practitioners justify their use of R&S by nine reasons, divided into four categories: perceived immediate antecedents, observables behaviors, external constraints and clinical and readaptative goals. The addition and interaction of these reasons triggers the use of R&S. Conclusion. Studying the reasons derived from the interaction situation leading to R&S rather than those related to the individual or the environment has enhanced our knowledge of the practitioner’s clinical judgment. The identification of categories could help to improve practitioners’ training, in regards of the factors contributing to the use of the R&S as well as address preventive clinical strategies to reduce their use.

Keyphrases: Restraint, Seclusion, Educators, Youth care setting, Residential treatment center, Clinical judgement
La réponse différentielle à la musicothérapie chez les jeunes hospitalisés en pédopsychiatrie: le rôle prédictif de la réactivité cardiaque sur le changement d'affect

This project is part of the evaluation of a receptive music therapy intervention implemented in the child psychiatry unit hospital university center Sainte-Justine for young people hospitalized in child psychiatry. A previous study showed that this intervention was associated with a significant affect’s change. We then want to check whether cardiac reactivity is a predictor of a differential emotional response to music therapy sessions for young people hospitalized in child psychiatry. We examined whether a distinct cardiac responsiveness pattern while listening to music was associated with a greater decrease in negatives affects and situational anxiety. 20 participants attended music therapy sessions based on a relaxation technique that supports emotional regulation. The affect’s change was measured immediately before and after the sessions. Cardiac responsiveness was monitored continuously while listening to music during sessions. The results indicate a gradation in the affective response as a function of the patterns of cardiac reactivity that goes in the expected direction. The "descendant" profile is associated with a greater improvement of the affect, the "stable" profile, with less improvement and the "upward" profile, with an even more modest improvement. More than half of the participants showed an increase in their heart rate while listening to music. This high proportion of paradoxical cardiac responses to an intervention aimed at progressive relaxation is discussed from several angles.

Keyphrases: music therapy, child psychiatry, emotional regulation, differential response, cardiac reactivity
Étude spatiale et temporelle d’un plasma produit par une onde électromagnétique de surface impulsionnelle dans l’hélium

The helium 3 isotope with an induced polarization, already useful in nuclear research, is identified as an ideal marker to improve medical magnetic resonance imaging of the respiratory tract. The most common mean of production used is metastability exchange optical pumping, however this process is not sufficient for large scale use of helium 3. Publications that seeks to optimise the MEOP process neglect the first step, which is the production of a helium plasma in which the process work. We have the goal to identify optimal conditions for metastability exchange by studying a helium plasma produced in different conditions. Plasma produced by an electromagnetic surface wave was seen as a possible lead because of its simplicity and operating flexibility. The operation of the plasma in a pulsed regime makes it possible to study certain properties unique to this mode of operation, and also to study in a fundamental way the formation of the discharge in unprecedented conditions. To this end we have used time resolved imaging and spectroscopic measurements. These revealed the importance of the surface-wave reflection on the ionisation front, which creates a standing waves. We have also identified a regime transition between 5 and 50 Torr and evaluated the required time for the temporal stabilisation of the discharge.

Keyphrases: Gaz, Surfaguide, Plasma micro-onde, Gas, Helium, Surface Wave, Pulsed Plasma, Microwave Plasma, Standing Wave
Relaxation et cristallisation du verre mou de chalcogénure Ge2Sb2Te5 après impact d’ions lourds à basse énergie

This text presents a nano-calorimetric study of the phenomenon of structural relaxation, crystallization and glass transition affecting Ge2Sb2Te5 (GST) glass. To analyze these pro- cesses, we measure the heat exchanges while the material is thermally annealed. To do this, the thin layers of GST (32 nm) are deposited on the SiNx membrane of a nanocalorimeter (NC) using an RF triode magnetron sputtering cathode. The specimens are then subjected to various analyzes (RBS, XPS, XRD, ERD, EDS and AES) to determine their stoichiome- tries and their morphology. It is determined that the concentration of the elements Ge, Sb and Te is 20 %, 21 % and 60 % respectively. The uncertainty on these values is estimated at ± 3 %. We also seek information on the kinetics of processes like crystallization (Tc) and glass transition (Tg). To do this, we modify the heating rate (between 14 and 184 kK/s) in order to check the influence of this parameter on the temperatures at which the phenomena occur. The speed of these reactions coupled with the use of a method developed by Kissinger allows to deduce the activation energy of these phenomena (Tg - 1.4 eV ; Tc phase FCC - 2.5 eV). Then, GST is damaged by bombardment of heavy Au ions at low energy (10 keV). This operation aims to create non-equilibrium regions of nanometric size in the GST. The thermogram of the experiment is recorded thereafter. The comparison of calorimetric curves to those obtained for a-Si makes it possible to deduce that this phenomenon can be explained by a broad distribution of activation energies. Parameters such as annealing rate, fluence and implantation temperature have been varied to better understand the phenomenon. It has been shown that relaxation is not affected by the glass transition. Our results also seem to establish that Tg is robust to implantation since it always occurs at the same temperature, regardless of implantation fluence (1012 - 1014 Au/cm2 at 10 keV). Keywords : Nanocalorimetry, glass transition, relaxation, crystallization, implantation

Keyphrases: relaxation, implantation, Nanocalorimetry, glass transition, crystallization
Étude électrique et spectroscopique d'une décharge nanopulsée dans l'hélium à la pression atmosphérique

This thesis presents an electric and spectroscopic study of discharges created by repetitive  nanosecond pulses at atmospheric pressure in helium. Using optical emission and absorption  spectroscopy coupled with predictions from a collisional-radiative model of n=3 helium levels, the  space-time distribution of the electron temperature was obtained in such plasmas. More  specifically, imaging measures in the inter-electrode gap were first carried out to study the temporal  evolution of a nanopulsed discharge in a dielectric tube. We have observed that the rectangular  voltage pulse leads to the creation of two current peaks (therefore discharges) corresponding to its  rise and fall, respectively. The light intensity measurements allow the observation of a Townsend  breakdown during the first discharge and the experimental acquisition of Townsend’s first  coefficient for the electronic multiplication. This first discharge, resulting in the apparition of a  negative glow, does not contain metastable helium atoms (n=2) yet. Also, very high electron  temperatures are obtained, which concurs with the high luminosity from the discharge. Following  a short period where there is no helium emission, a strong rise in emission from impurities is  collected, a consequence of the metastable population increase. Finally, the second discharge  appears at the fall of the voltage pulse. Its origin being the accumulation of charges on the dielectric,  this discharge is shorter and weaker from a light intensity standpoint. Also, metastable presence  linked to Penning ionization mechanisms leads to smaller values of electron temperature.

Keyphrases: Nanopulse, Pulsed discharge, Nanopulse, Atmospheric pressure, Helium, Electron temperature, Metastable number density, Spectroscopy, Collisional-radiative model
Classification de systèmes intégrables en coordonnées cylindriques en présence de champs magnétiques

In absence of a magnetic field, the quadratically integrable three-dimensional motion of a classical or quantum particle subject to a scalar potential can be characterized by the Hamiltonian and two integrals of motion which are quadratic in the components of momentum. There exist eleven types of such integrable systems, each corresponding to a system of coordinates in which separation of variables in the Hamilton-Jacobi or Schrödinger equation is possible. In each case, it is then possible to find a more explicit form for each of the integrals of motion and for the scalar potential.  It seems logical to look at the influence of a magnetic field for each of these situations. The process consists of postulating the same type of integrals of motion previously found for each type of motion, add a vector potential to the Hamiltonian and redo the classification work. This master's thesis will mostly treat the case of cylindrical coordinates. It is important to note that in the presence of a magnetic field, these integrals do not guarantee a complete separation of variables, but a partial separation is possible in many cases.

Keyphrases: classification, 3d, hamiltonian, integrability, conserved quantity, integrals of motion, scalar potential, magnetic field, classical, quantum, euclidean space, separation of variables, poisson bracket
Synthèse et étude des caractéristiques thermodynamiques du Ce 2 Zr 2 O 7 monocristallin

The goal of this project was to grow single crystal samples of Ce 2 Zr 2 O 7 and to study their thermodynamic properties.  Ce 2 Zr 2 O 7 is a rare-earth pyrochlore compound and a quantum spin liquid candidate at low temperatures.  Pyrochlores based on Dy and Ho rose to prominence due to their spin ice ground state whose primary excitations of the ground state are delocalized magnetic dipoles: so-called magnetic monopoles. The small magnetic moment of Ce 3 + ions, compared to the previously studied isostructural com- pounds Dy 3 + and Ho 3 + , might allow quantum effects to be dominant like in the case of Yb. Theoretical studies of the Ce 3 + placed on the pyrochlore lattice predicted a dipole- octopole quantum spin liquid ground state.  Specific heat and ultrasound measurements allow us to probe these low energy interactions. The peak in specific heat measurements at constant pressure follows the same magnetic dependence as previously measured for polycrystalline samples, and the entropy of the system follows that of a spin ice system, at low temperatures.  For the acoustic wave measurements, we measured the change in sound velocity and the ultrasound attenuation for both transverse and longitudinal prop- agation modes, with magnetic field applied along the ( 111 ) crystallographic direction. The softening of the velocity measurements at high field for both transverse and longi- tudinal modes for temperatures below 0.8K are trademarks of quantum fluctuations in the system.  The global hysteresis measured for those parameters appears to be from a ferromagnetic coulomb phase of the system.  We also observe a first order gas-liquid type transition for T < 0 . 04 K, with the sudden drop of attenuation and a broad peak in the velocity around 2.5 T.

Keyphrases: Pyrochlores, Quantum fluctuations, Ultrasound measurements, Spin ice, Magnetic monopoles, Pyrochlores, Single crystals
Le lien entre les patrons d’exposition à la lumière bleue et l’avancement du cycle éveil-sommeil au cours du vieillissement

Aging is associated with phase advance of circadian rhythms including the sleep-wake cycle. Light, especially blue light, is the main environmental time cue of the circadian timing system. Is it therefore possible that change in light exposure patterns to light may underlie the phase advance of the circadian clock in aging. No studies have evaluated blue light exposure patterns in aging. The main objective of this study is to compare white and blue light exposure patterns in young and older individuals. Fifteen young (20-30 years old) and 13 older participants (60-80 years old) wore an ambulatory photometer for one week to measure light exposure. Older participants, compared to the younger one, went to bed and woke up earlier. Our results showed higher relative blue light exposure in the morning hours and lower relative blue light exposure in the evening in older individuals compared to the younger participants. Similar results were obtained for absolute and relative white light exposure. Young and older participants did not differ in absolute and relative white and blue light exposure when adjusted for wake up time and bed time, which suggest that age-related changes in the sleep-wake cycle is not explained by habitual patterns of light exposure.

Keyphrases: Aging, Sleep, Blue light, Circadian rhythms, Daily light exposure, Clinical neuropsychology