NCube/papyrus huggingface dataset:
L’influence de la stratégie de navigation dans un environnement virtuel sur l’activité cérébrale en EEG

The importance of our ability to orient ourselves or navigate in a given environment is pictured by our ability to find our way back when we are lost. As it must orientate itself in a given environment, the human being spontaneously uses navigational strategies to successfully arrive to its destination. Every individual instinctively uses a strategy that’s either allocentric or egocentric, depending upon which structure among the hippocampus or the caudate nucleus has the most predominant volume. As the allocentric strategies tend to be associated to a more important hippocampic volume, the egocentric strategies tend to be linked to a lesser one. There are important connections between the used strategy and one’s hippocampic volume. An important hippocampic grey matter volume and activity are associated to allocentric navigational strategies, as a lower volume and activity are associated to the use of egocentric strategies (West & al., 2015; Iaria, Petrides, Dagher, Pike & Bohbot, 2003; Bohbot, Lerch, Thorndycraft, Iaria & Zijdenbos, 2007; Lerch & al., 2011; Etchamendy, Konishi, Pike, Marighetto & Bohbot, 2012; Konishi & al., 2013). The goal of this master’s thesis is to demonstrate that platform video game training allows to stimulate hippocampic activity. Using an electroencephalogram, we have been monitoring the theta waveband frequential activity (4-8Hz), as we know it to be linked to hippocampic activity, but also, gamma wavebands (30-50Hz). As we estimate that there should be a significant augmentation of theta activity (which is influenced by hippocampic activity) on both experimental groups, it should be more important among the participants using instinctively an allocentric strategy. After determining which strategy is used by each of the 39 neurotypical young adults we have tested, we have measured their cerebral activity with an EEG while they were playing “Super Mario 64” in 15-minute periods separated by resting state phases.  Our results show that the allocentric users have a theta activity augmentation when tested on active levels (which include navigation soliciting objectives) compared to the control level (repetitive movement, without definite navigation objectives) in all analyzed scalp region (frontal, central, parietal, occipital). Participants using an egocentric also show a significant augmentation of theta activity in the active levels compared to the passive ones but only in the frontal region. These results demonstrate that EEG can be used to highlight the different cerebral activities issued during spatial navigation and bring out the interest of this technique.

Keyphrases: EEG, Neuropsychology, Spatial Navigation, Spatial Navigation Strategies, Electroencephalogram, Video Games, Hippocampus, Caudate Nucleus, Hippocampus Activity, Cerebral Wavebands, Theta Wavebands, Gamma Wavebands
L’association prospective entre le climat de sécurité en milieu scolaire et les symptômes dépressifs chez les adolescents : une étude multiniveaux

Objective: School violence has become a major issue in Canada. The impact of the school climate on the emotional well-being of students is therefore important to consider. The purpose of this thesis is to use multilevel analysis to examine the prospective association between school safety climate and depressive symptoms in adolescence and to determine whether adolescent sex moderates this association. Method: The sample used for the analyses is composed of 5,262 students from 71 secondary schools in Quebec, Canada. Students were followed annually. Safety climate was measured using the Socio-educational environment questionnaire. Depressive symptoms were measured using the Center for Epidemiological Studies (CES-D). Longitudinal multilevel regressions were performed to test the link between safety climate in grade 8 and depressive symptoms in grades 10 and 11. Sex was tested as a moderator. Multilevel analysis allowed to study safety climate at the school (L2) and student (L1) levels. Analyses controlled for school characteristics and individual characteristics including baseline depressive symptoms and victimization.  Results: Safety climate at the school-level and student-level predicted subsequent depressive symptoms before adding control variables. After adding these variables, results showed a weak, but significant link between student-level safety climate and depressive symptoms. The moderating analyzes show that this relationship is only significant for girls. No association was detected between the safety climate at the school-level and depressive symptoms after including control variables. Conclusion: This study suggests that individual perception is more predictive of depressive symptoms then the mean aggregate perception of safety climate in a school. Students who perceive their school climate as less secure than the norm are at increased risk of developing symptoms over time. This thesis highlights the importance of studying the impact of safety climate on the well-being of adolescents in schools.

Keyphrases: Adolescence, Longitudinal, Safety climate, Depressive symptoms, Adolescence, School, Longitudinal, Multilevel
Lien entre l’accessibilité perçue d’une substance psychoactive et sa consommation : rôle modérateur de la perception du risque à consommer à l’adolescence

Adolescence is a developmental period characterized by the discovery of oneself and one's environment through experiences. Psychoactive substance use is one of them. Although it can be described as a normative experience, initiation of drug and alcohol use among adolescents is a considerable risk factor in the development of diverse psychosocial problems. It is therefore important to understand this phenomenon. The purpose of this research project is to answer the following question: does the perception of the risk associated with the use of a substance (alcohol or cannabis) play a moderating role in the relationship between the perceived accessibility of the substance, measured in secondary 1, and its reported use in secondary 2? This question is legitimate since access to substances and the perceived risk of consuming them have been known to predict use. Yet, substances that are easily accessible were shown to be rarely consumed. The sample included 142 participants enrolled in Secondary 1 at the first time of measurement. All the variables used in this longitudinal study are self-reported using a questionnaire. Logistic regression analyses were performed for alcohol and cannabis separately. Overall, no significant results could be identified in the analysis model targeting alcohol. However, an interaction effect has been detected in the model targeting cannabis, indicating more specifically that adolescents who perceive a low risk of using cannabis are more likely to use this drug when perceived access increases.

Keyphrases: Cannabis, Adolescence, Longitudinal, Psychoactive substances use, Initiation, Alcohol, Risk perception, Perceived acces, Longitudinal
Évaluation formative d'ateliers visant à soutenir les parents immigrants dans l'adaptation de leur rôle parental

Immigrant families and refugees settling in Quebec face challenges upon their arrival. Initiatives are put in place by the province to support parents who are actively seeking work or trying to learn French. However, they also seem to need help adapting to their parenting role, but few resources are available. The Familles immigrantes en transition workshops were developed to answer these needs. The objective of this Master’s thesis is to evaluate the implementation, that is, the conformity, the participants’ appreciation, as well as the effects of the workshops as perceived by the parents and group leaders. The qualitative analyses indicate a gap between the initial planning and the implementation of the workshops. Hence, these results indicate a low compliance, more specifically regarding the duration and the way the workshops are animated. Nonetheless, parents express their appreciation for the workshops, highlighting qualities regarding the animation and the group leaders, as well as the relevance of the content and activities offered. Effects are also perceived for four everyday life aspects: their intellectual life as new knowledge is developed, their social life as social isolation is decreased and relationships between parents are developed, and their emotional life because of increased self-confidence and decreased stress. Moreover, changes are reported in the parents’ behaviors and habits. In sight of these results, recommendations are provided for future implementation of the workshops.

Keyphrases: intervention, immigration, parenting role, parenting pratices
La relation entre les comportements extériorisés et l’engagement scolaire : l’effet modérateur de l’implication parentale dans le suivi scolaire

School engagement is a critical aspect of student success. However, a portion of students follow a less optimistic path of engagement, especially those with disruptive behaviors (Wang & Fredricks, 2014). The aim of this study is therefore to verify whether parental involvement in education moderates the relationship between externalized behaviors of these elementary students and their school engagement. Data of 731 grade three to grade six students from disadvantaged backgrounds was collected at the beginning and at the end of the school year threw validated questionnaires. Multiple hierarchical regressions were performed to verify the unique and shared contribution of four dimensions of parental involvement to cognitive and behavioral engagement. The results show that homework support is positively associated with school engagement, while parent-school relationship is negatively associated to it. Results also show that parental aspiration for their child’s education moderates the negative link between externalized behaviors and behavioral engagement, whereas homework support and parent-child communication protect cognitive engagement of these students. Overall, these findings suggest the importance of promoting parent involvement in their child's education to prevent future disengagement, especially with students who exhibit externalized behaviors.

Keyphrases: school engagement, disengagement, parental involvement, externalized behaviors
Exploration des manifestations d’altérisation entre les différents acteurs du système de soins du Nunavik

First Nations and Inuit of Canada bear a disproportionate burden of mental health problems and only partially benefit from the Canadian healthcare system. This is partly due to discrimination in the healthcare system that may be due to racism or othering experiences. Othering, defined as the process used to name those who are considered to be different from oneself, influences the nature of these interactions between individuals. Fraser et al. (2017) found many interpersonal and cultural tensions between patients and healthcare professionals in the Nunavik region. These tensions harm the collaboration, the treatments offered and the services in a region where the health needs are urgent. However, differentiation from others can also be necessary in a collaboration process. The present study is a secondary analysis of the interviews collected during Fraser et al. (2016)’s project. The present study aims to explore othering mechanisms from a tension standpoint. A qualitative thematic analysis exploring the different narratives and contexts present in 12 interviews with inuit and non-inuit participants was completed. The results reveal the presence of professional, individual, systemic and ethnic othering. The othering present in the participant’s narratives seems to serve to identify with different social groups and maintain a positive identity. Different contextual elements particular to the Nunavik region influence the emergence of the othering narratives and help maintain the identities and the social groups named by the participants. Finally, by reflecting on their own identities, the healthcare workers and patients could improve their interactions with their peers, the collaboration in the system and consequently, the health and well-being of the Inuit people in Nunavik.

Keyphrases: Nunavik, Inuit, collaboration, Indigenous, Othering, Healthcare services, Health, Well-being
Évaluation de la mise en oeuvre et des effets perçus du programme Vestiaire des pères

Recently, father involvement has been redefine. Fathers now play numerous roles with their children. Many community organisations assist fathers so that they can manage this new reality. Unfortunately, government services stand behind, partly because of the rigidity of their organizational structure adapted to mothers’ needs. Vestiaire des pères is a program who follows from an innovative collaboration between Coopère Rosemont, a community service provider, and the Centre jeunesse de Montréal – Institut universitaire, a government agency. Vestiaire des pères suits every father who wants to share his experience of fatherhood. Many goals are aimed; reaching out so that they are not isolated, socialize and help each other. This qualitative study aims to describe both the logic model of the program and the implementation process of Vestiaire des pères and to identify the perceived effects on fathers. The sample includes six fathers and four educators that took part of the program. Different sources of information were collected and analyse to reveal Vdp’s implementation process and logic model. Results suggest that fathers from many different backgrounds were part of the program, even fathers in vulnerable situations. Overall, educator’s attitude towards father’s background, profile, strengths and weaknesses is the most appealing setting that helps create a mutual-aid environment. The results also showed that inconsistency in Vdp’s elaboration process led to difficulties during implementation process. Finally, many suggestions are propose to improve this innovative program.

Keyphrases: engagement paternel, Social program, Activation relationship theory, Father’s involvement, Mutual-aid groups, Implementation evaluation, Psychoeducation
Victimisation par les pairs et rendement scolaire au début du secondaire : le rôle médiateur de l’engagement scolaire

This study examines to what extent peer victimization at the beginning of high school is associated with the subsequent school achievement of students. Also, this study aims to assess if behavioral, affective and cognitive dimensions of students’ school engagement could possibly act as a mediator factor, and explain the relationship between peer victimization and academic achievement. The sample is made with up of 683 students in 7th and 8th grade in the Montreal area. For this longitudinal study, peer victimization was self-reported by the students, and evaluated in 7th grade. The three dimensions of school engagement were also self-reported by the students, and evaluated at the end of 7th grade, and at the beginning of 8th grade. School achievement was evaluated at the end of both school years (by checking final grades in the students’ report card). Results show that peer victimization in 7th grade is negatively associated with school achievement in 8th grade. In addition, the relative decrease of affective school engagement at the beginning of high school, but not behavioral or cognitive, partly explains the deleterious effect of peer victimization on students’ subsequent academic achievement.

Keyphrases: adolescence, peer victimization, behavioral school engagement, affective school engagement, cognitive school engagement, school achievement
Étude spectroscopique et électrique de décharges contrôlées par barrières diélectriques en régime multi-pics

The purpose of this master thesis is to characterize a Dielectric Barrier Discharge (DBD) at atmospheric pressure in helium in homogeneous regime, but with multi-peaks, which means that it exhibits more than one discharge current peak per half-cycle of the applied tension. The intention here is to shed some light not only over fundamental parameters (temperature, metastable density, etc.), but also their respective space and time evolution. In that line of thought, electrical and spectroscopic measurements of these discharges with one or more discharge current was done, with impurities mixed in the main gas (namely argon, diatomic oxygen and/or hexamethyldisiloxane). With the help of measurements of populations of n=2 and n=3 levels in optical emission and absorption spectroscopy, coupled with a collisional-radiative model, we were able to show that the incorporation of impurities play a crucial role in the emergence of multipeaks. Moreover, that incorporation has the effect of making the electron temperature spike in between discharges through a half cycle, as well as quenching the helium metastables. The metastable spectroscopic signature is rapidly decreasing and becomes negligible as the impurity is added. The study extended thereafter to conditions useful to thin film depositions, that is to say in presence of oxygen and an organosilicated precursor. In these conditions of reactive plasmas, it was impossible to take any spatio-temporal imaging and to measure metastables densities. We therefore studied the discharges in terms of space and time averaged measurements for a half-cycle of the applied voltage. The trend of the mean electronic temperature is going up while the concentration of impurities is increasing in the helium plasma. The same trend is observed in the absorbed and dissipated power by electron, which is predicted by the transport equation of the electron’s energy.

Keyphrases: DBD, atmospheric pressure, multi-peaks, optical emission and absorption spectroscopy, electronic temperature and density, metastable density
Preuve de concept in vitro de la navigation par résonance magnétique en conditions physiologiquement réalistes

This research aims to demonstrate the feasibility of magnetic resonance navigation (MRN) as a treatment for unresectable, malignant liver tumors. This method consists in steering magnetic drug-eluting microbeads in hepatic arteries towards diseased liver lobes using an unmodified magnetic resonance imaging (MRI) scanner, with regards to physiological, anatomical and technological limitations. To reproduce a physiological flow during the MRN experiment, the arterial flow was measured using phase contrast MRI on seven porcine models. In addition, to evaluate the feasibility of creating in vivo flow conditions that are suitable for MRN, a balloon catheter positioned in the proper hepatic artery was used simultaneously with a 0.5 mL/s saline infusion to reduce mean flow velocity and systolic-diastolic variation. In parallel, to characterize the arterial flow profile as a function of embolization level for treatment planning, a quantitative digitally subtracted angiography (qDSA) program was developed and used to measure arterial flow rate in individual vessel segments of a realistic porcine hepatic arterial phantom under fluoroscopy with injection of contrast agent at 0.25 mL/s. Then, a proof-of-concept in vitro MRN experiment was performed under flow rate conditions similar to those measured in vivo to demonstrate the feasibility of using a 20 mT/m gradient sequence in an unmodified MRI scanner to selectively steer aggregates composed of 20 magnetic microbeads in a one-bifurcation hepatic arterial phantom. Phase contrast imaging on pigs revealed that using a balloon catheter decreases the mean hepatic arterial flow velocity from 20.5 ± 15.3 cm/s to 8.4 ± 5.0 cm/s (uncertainty representing the standard deviation) as well as the systolic-diastolic variation from 24 ± 14 cm/s to 4.9 ± 2.3 cm/s, which is compatible with MRN. The qDSA program provided a flow estimate in individual segments with a root-mean-square error of 34%, but further development is needed to allow the characterization of the arterial flow profile as a function of embolization level. For the MRN experiment, the steering efficiency obtained was 100%. This research shows that the use of a balloon catheter reduces arterial hepatic flow velocity and variation and that qDSA is a promising flow measurement method in the context of transarterial chemoembolization. In addition, this research shows that MRN is possible under realistic physiological and anatomical settings, with reduced flow and with an unmodified MRI scanner.

Keyphrases: Hepatocellular carcinoma, Transarterial chemoembolization, Phase contrast magnetic resonance imaging, Quantitative digitally subtracted angiography, Magnetic resonance navigation
Calculs numériques du spectre Raman double-résonant du phosphorène

Presented here is a study on the second-order Raman spectrum of exfoliated black phosphorus. Four new defect-induced Raman modes were identified in the A1g and A2g regions in few-layers black phosphorus samples. In order to understand the origins of these modes, we computed the double-resonant Raman spectrum of phosphorene from DFT calculations. We confirm the identification of these modes caused by a phonon with a non-zero momentum and a defect. Furthermore, we conclude that the corresponding peaks are the result of nesting of electrons and holes in the first electronic valley. Predictions of the dispersion of these peaks versus the incident energy were made. This study lays down the basic understanding of the Raman spectra of few-layers black phosphorus samples in presence of defects. It opens new ways for possible characterizations of black phosphorus from its Raman spectrum. This project is the result of a collaboration between Michel Côté’s group from the Physics Department and Richard Martel’s group from the Chemistry Department at Université de Montréal.

Keyphrases: second-order Raman spectroscopy, black phosphorus, phosphorene, double-resonances, defect-induced modes
Étude de la dynamique vibrationnelle de pérovskites 2D hybrides organiques-inorganiques par spectroscopie Raman

In this work, we investigate the vibrational spectrum of two distinct two-dimensional hybrid organic-inorganic perovskites by means of non-resonant Raman spectroscopy. Their particular 2D structure is composed of inorganic lead-ioded layers separated by organic cations, which induces a quantum and dielectric confinement. Two different perovskites are investigated in this work. The first one is (C4H12N)2PbI4 which stands for (NBT)2PbI4 and the second one is (C8H12N)2PbI4, also named (PEA)2PbI4. These two derivatives were carefully selected in order to probe the effects of their organic cation on the lattice dynamics. The organic cation in (NBT)2PbI4 is composed of a linear alkyl group (C4H12N)2=(NBT)2 whereas the one in (PEA)2PbI4 contains a phenyl-substituted ammonium (C8H12N)2=(PEA)2 derivative. Low-temperature Raman measurements revealed five main inorganic modes and six organic modes for (NBT)2PbI4, as well as one inorganic mode and three organic modes for (PEA)2PbI4. In addition, temperature dependent Raman spectra of these two materials revealed several differences in the dynamic disorder as the organic cation seems to have an important role, especially for (PEA)2PbI4. These results highlight the importance of the organic cation in lattice reorganization and dynamic disorder for 2D hybrid organic-inorganic perovskites.

Keyphrases: (NBT)2PbI4, (PEA)2PbI4, Phenyl, 2D hybrid organic-inorganic perovskites, Raman spectroscopy, Dynamic disorder, Alkyl