NCube/papyrus huggingface dataset:
Impacts de l’urbanisation et de l’historique d’utilisation des sites sur la diversité taxonomique et fonctionnelle de la flore des milieux humides non-riverains

Urbanization is one of the leading causes of biotic homogenization. This master aims at understanding the effects of urbanization and of land use legacy on vegetal community assembling processes in isolated wetlands. Floristic inventories were carried in 67 isolated wetlands (marshes and swamps) of Laval. Taxonomic richness, functional diversity as well as taxonomic and functional beta diversity were compared according to wetland type (marshes or swamps), species origin (indigenous or exotic), present-day urbanization (natural or urban) and land use legacy (wetland or agricultural). No impact of urbanization and former agricultural use was detected on the taxonomic richness and functional diversity, but these two parameters differed according to species origin and wetland type. As well, urbanization and former agricultural use did not induce differences in beta diversity but were associated with important shifts in taxonomic and functional community composition. While marshes were more influenced by actual urbanization, the composition of swamps rather reflected the effects of in situ past disturbances. Moreover, exotics contributed to homogenize plant communities, both taxonomically and functionnally. Overall, my results indicate that the impacts of urbanization on floristic communities of isolated wetlands call for the integration of multiple factors at different temporal scales.

Keyphrases: Agriculture, Biotic homogenization, Marshes, Swamps, Exotic species, Alpha and beta diversity, Functional traits, Land use legacy, Community assemblages
Évaluation des facteurs influençant l’avortement des oeufs de la punaise marbrée Halyomorpha halys Stål (Hemiptera: Pentatomidae) par la guêpe parasitoïde Telenomus podisi Ashmead (Hymenoptera: Scelionidae)

Parasitoids develop on, or, inside a host they kill during their development. They are often used in biological control because they have the ability to reduce and control populations of organisms considered harmful. We investigated the ability of the parasitoid wasp Telenomus podisi to induce the abortion of its host eggs: the exotic stink bug Halyomorpha halys. This new species association does not allow the wasp to reproduce, but it induces some abortion of the eggs of the host, nevertheless variable from one wasp to another. Our three experiments have determined that 1) the abortion rate follows the size of the egg, whether parasitized or not. That this abortion rate is even greater when parasitized by smaller wasps 2) The abortion rate is explained to 18.2% by wasp genetics (h2 = 0.182). 3) It is difficult to generate a population of T. podisi capable of inducing a high abortion rate after 5 generations of selective breeding. With these results, we are opening a track in biological control against the pest insect H. halys. The use of small wasps would reduce the stink bug reproduction. But also, at the light of the contents of this thesis, a selective breeding program could be optimized to produce efficient wasps in the abortion of H. halys eggs.

Keyphrases: Egg abortion, Hosts, Selective breeding, Heritability, Biological control, Nonreproductive mortality
Le microbiome fongique de la rhizosphère du canola : structure et variations

The fungi in the rhizosphere have a large influence on plant development and growth. Some of these micro-organisms protect plants against pathogens, mitigate the impact of abiotic stress, or facilitate plant nutrition. These organisms influence each other and form complex webs of interactions. Deciphering the structure and function of the fungal microbiome of crop plant rhizosphere is a necessary step toward optimizing the efficiency of plant production. We tested the hypotheses that (1) the diversification of cropping systems influences the fungal microbiome of canola rhizosphere, (2) canola has a fungal core microbiome, i.e. a set of fungi that are always associated with canola, and (3) that some taxa have a determining influence on the structure of the communities (hub-taxa) within the core microbiome. In 2013 and 2016 we used the canola (Brassica napus) phase of five cropping system at blooming stage, from the less to the most diversified, that included one of two types of canola (Roundup Ready® and Liberty Link®), in an existing long-term (6 years) field experiment.  The experiment has a randomized complete block design with four blocks, and is replicated at three locations: Lacombe (Alberta), Lethbridge (Alberta) and Scott (Saskatchewan). Our results show that crop diversification has significant impact on the structure of rhizosphere fungal communities. We also discover and described a canola core microbiome made of 47 OTUs in 2013 and identified Preussia funiculata, Schizothecium sp., Mortierella sp., Nectria sp. and two other unidentified taxa (OTU12 and OTU298) as the hub-taxa among this core. However this core microbiome was variable and could identify only one member in 2016 : Olpidium brassicae. Our results confirmed the effect of crop diversification upon the fungal microbiome of canola and are presented as a basis for the development of ecological engineering strategies for the improvement of canola production.

Keyphrases: Microbiome, Brassica napus, rhizosphere, community ecology, Network analysis, Fungal communities, Microbial egology, Agrosystems, Crop rotations
Impact du boisement des tourbières ombrotrophes sur leur diversité floristique

This study aims to understand the effects of recent tree encroachment on plant richness and diversity of Sphagnum-dominated bogs isolated in an agricultural landscape. A nested paired sampling design was used to compare plant species richness and beta diversity between open and forested habitats of 14 bogs in the St. Lawrence Lowlands. We evaluated the impact of tree encroachment at regional and local scales (between and within bogs, respectively). Tree basal area, canopy openness and stand age were evaluated in forested habitats. We used permutation paired sample t-tests to compare species richness between open and forested sites. Beta diversity was calculated as between-site similarities in composition, and differences were evaluated using tests for homogeneity in multivariate dispersion. Forested habitats had greater species richness than open habitats due to enrichment by facultative and non-peatland species as well as by mid- and shade tolerant vascular plants. At both scales, this species enrichment was associated with floristic differentiation (increase of beta diversity), although at regional scale, this was true for bryophytes only. Tree basal area had a positive influence on forested habitats species richness. These compositional changes are expected to increase similarity between bog flora and upland vegetation, and consequently decrease regional diversity.

Keyphrases: Beta diversity, Biotic homogenization, Bogs, Multivariate dispersion, Species richness, Species turnover, Tree encroachment
Contribution of the subthalamic nucleus to visually guided locomotion

The Basal ganglia (BG) plays an important role in locomotor control. This is emphasized by the impaired walking of patients with neurodegenerative disorders that affect the BG such as Parkinson’s disease. One important structure in the BG is the subthalamic nucleus (STN), which acts as an input structure for the BG and projects to its output structures. Although the STN has been shown to display movement-related activity during reaching, the nature of its contribution to the control of locomotion, together with the characteristics of its neural activity during locomotion, is poorly known. In order to better understand this contribution, we examined the properties of the neural activity in the STN during unobstructed and visually guided locomotion. To do so, we recorded single neurons in an intact cat trained to walk steadily on a treadmill and to step over obstacles attached to the treadmill belt and moving at the same speed. We recorded 40 neurons which activity was related to the movement of the forelimb during the task. We found that during unobstructed locomotion, many of these cells (30/40) showed phasic step-by-step modulation of their activity pattern, mostly during the swing phase. Most of these swing-related cells discharged throughout the swing phase with no relationship to changes in the pattern of different muscle groups. During voluntary modifications of gait, 37/40 cells, including both cells that were and were not modulated during unobstructed locomotion, changed their firing rate in relationship to the step over the obstacle. The changes observed were mostly increases of activity, but a few cells showed decreases of activity and some showed a decrease followed by an increase of activity. These changes occurred either before the modified step and were classified as step-advanced activity, or they occurred during the modified step and were classified as step-related activity. Step advanced cells mostly showed limb-independent activity, while step related cells showed limb-specific activity. This is the first detailed account of the contribution of the STN to the control of locomotion and our results indicate that the STN is involved in the control of both unobstructed and visually guided locomotion. The results suggest that during unobstructed locomotion, the STN contributes to the general control of the limb trajectory and to both the planning and execution of voluntary changes of gait.

Keyphrases: Basal ganglia, subthalamic nucleus, locomotion, voluntary gait modification, visually guided locomotion
Changes in Frame of Reference After Exposure to Emotional Stimuli

The goal of the current study was to demonstrate the possibility that elderly people represent the climax of emotional development through a perceptual shift in the importance of negative stimuli over decades of life. The proposed hypothesis was that the positivity effect or positivity bias (PE) is the result of desensitization to chronic negative stimuli through life experience. This was done as a proof of principle by inducing the PE in young adults after exposure to a specific type of emotional stimuli. Specifically, 39 participants were randomly assigned to two groups, one where they were only exposed to sad faces and the other only to neutral faces. Participants completed baseline and comparison ratings of their group’s emotional stimuli, and were equally exposed while completing a working memory task to maintain their attention. As this was an explorative study, a blocked design was used to capture the time required to desensitize in normal young adults. We controlled for depressive symptoms, anxiety, and controlled for mood and arousal pre and post the experimental procedure. Just like elderly adults in the PE, the young adult participants rated negative stimuli as less negative, and neutral stimuli as more positive over time. This suggests that the PE represents a climax of normal emotional development where humans slowly desensitize to negative stimuli over time. Keywords: Positivity Effect; Positivity Bias; Frame of Reference; Emotional Development; Human Development; Priming; Elderly; Aging; Young Adults; Emotion.

Keyphrases: Positivity Effect, Positivity Bias, Frame of Reference, Emotional Development, Human Development, Priming, Elderly, Aging, Young Adults, Emotion, Priming
Contribution respective du rejet par les pairs et de l’agressivité des amis aux fonctions réactive et proactive de l’agressivité : une étude associative génétiquement contrôlée

The first objective of this study was to determine the respective and possibly differential contribution of peer rejection and friends’ aggression to reactive aggression and proactive aggression when only one child per family is involved. This analysis corresponds to classical associative studies based on singular results (i.e. the results of one child per family). The second objective was to revisit the previous links while controlling for possible gene-environment correlations through the intra-pair difference method in monozygotic (MZ) twins. This method allows to control for genetic and environmental influences shared by MZ twins living together. The data was collected from 156 pairs of 10-year-old MZ twins (80 pairs of girls); these are part of the Quebec Newborn Twins Study (QNTS). The results show that proactive aggression is related to friends' aggression both in terms of singular outcomes and intra-pair differences. However, this study did not provide convincing results regarding the link between reactive aggression and peer rejection or friends’ aggression. Additional explanations are proposed to understand the results and guide future studies.

Keyphrases: Gene-environment Correlations, Reactive Aggression, Proactive Aggression, Friends ‘ Aggression, Peer Rejection, Genetics Factors, Transition Between Infancy and Adolescence
Le lien prédictif entre le sentiment d’efficacité des enseignants, l’engagement cognitif et les buts d’accomplissement des élèves de la 4e à la 6e année du primaire

Scholarly engagement is an important predictor of achievement and a protective factor against drop-out. Students’ cognitive engagement combined with mastery goals, instead of performance goals, represent a self-regulated learning that allows a better comprehension of the subject and higher aspirations in school. Many factors can favor self-regulated learning including teachers’ self-efficacy. This potential influence could be explained by the mastery classroom goal structure that the teacher sets. In this study, measures from 373 students and 38 teachers of 5 primary schools in poor neighbourhoods of Montreal were studied longitudinally with path analysis. The results show that a high teacher’s self-efficacy predicts students’ adhesion to mastery goals. It also predicts the mastery classroom goal structure that reduces students’ performance goals. Those results are, however, marginally significant and no link was observed between teachers’ self-efficacy and students’ cognitive engagement in this study.

Keyphrases: self-efficacy, cognitive engagement, mastery goals, performance goals, classroom goal structure
La relation entre les interactions positives avec l’enseignant et les pairs sur l'engagement affectif des élèves du primaire immigrants et non-immigrants en milieux défavorisés

A warm student-teacher relationship and the feeling of acceptance by peers have a positive influence on student engagement, especially for immigrant students with disadvantaged backgrounds. To our knowledge, however, no study has explored the joint influence of these factors on the emotional engagement of elementary students. Moreover, despite an interest in scientific articles on school engagement and its trajectories, as well as a rise in the immigrant population in several industrialized countries, research on the engagement of immigrant students in primary school is very limited. The aim of this study is to examine the possibly additive or multiplicative influences of warm student-teacher relationships, as well as the feeling of acceptance by peers, on the affective engagement in French and mathematics classes of immigrant and non-immigrant students from elementary schools in disadvantaged areas. Data were collected from 130 students in grades five and six over two consecutive years. Correlational analyses showed that a warm teacher-student relationship is positively correlated to the emotional engagement of all students in French and mathematics classes, compared to peer acceptance, which demonstrated no such correlation. In addition, the joint effect of these relational factors is only present among immigrant students. In fact, for immigrant students, the quality of the relationship with the teacher is positively associated with the increase of their emotional engagement in French, but only when students feel unaccepted by peers. The implications for research and practice are discussed.

Keyphrases: immigrants, school engagement, underprivileged backgrounds, teacher-student relationship, peer relations
Deep radio observations of a high-redshift galaxy cluster

In the centre of a cluster of galaxies lies a giant elliptical galaxy, dominating the others in terms of size and mass. This galaxy is called the Brightest Cluster Galaxy (BCG). Due to its privileged position near the gravitational potential well of the cluster, the BCG often hosts an actively accreting supermassive black hole. By releasing a tremendous amount of energy, this Active Galactic Nucleus (AGN) prevents the intracluster medium from cooling and condensing onto the BCG. This AGN feedback tends to quench star formation in BCGs.  However, the way AGN feedback operates in primitive BCGs is not well understood. Moreover, recent studies seem to indicate that high redshift BCGs have a significant amount of in-situ star formation. One of those stabursting BCGs is in the cluster SpARCS104922.6+564032.5 (shortened into SpARCS1049). It forms stars at a rate of 950 ± 100 M☉ yr−1 and has a morphology reminiscent of a major gas-rich merger. In this dissertation, I will present multiwavelength radio observations of SpARCS1049 obtained with the Very Large Array (VLA), focusing on its BCG.  I found three unresolved radio sources in SpARCS1049, including the BCG. The compact morphology of the radio emission from the BCG, as well as its good alignment with the galaxy optical centre, suggests that the radio emission originates from the AGN and not from star formation. However, the radio spectral energy distribution (SED) of this source is too poorly constrained to definitely determine its origin.  Assuming all the radio emission of the BCG comes from its AGN, I found that the level of radio activity is comparable to the average activity of lower redshift BCGs. This was unexpected because a previous study found an immense cold molecular gas reservoir of 1.1 ± 0.1 × 10^11 M☉ in the centre of SpARCS1049, suggesting that something partially prevents the infalling of the gas into the black hole.  I computed a new SED (from optical to radio) with my new radio flux measurements. I found that the bulk of the star formation probably takes place in the vicinity of the BCG but not inside. Since the star formation does not seem to be detected at radio wavelengths, we computed an upper limit on it and used this limit in combination with far infrared fluxes estimated from the SED to explore the extent of the star formation. I discovered that the star formation is probably very diffuse.  Finally, I explored three formation scenarios that could explain the unusual infrared morphology of the BCG and the presence of a substantial molecular gas reservoir, using radio data (and non-detections) to constrain them: 1) a major gas-rich merger, 2) gas stripping from several small galaxies or 3) a displaced cooling flow. I found that the major gas-rich merger scenario is unlikely, but more data are needed to favor one of the two remaining scenarios.

Keyphrases: Active galaxies, Galaxy clusters, Galaxy evolution, Galaxy interaction, Radio continuum in galaxies, Starburst in galaxie
Étude de semiconducteurs par des techniques de spectroscopie quantique

This master's thesis purpose is the implementation of a novel quantum spectroscopy technique for material characterisation. Quantum spectroscopy, like classical spectroscopy, is the study of materials using light. What differs is the type of light which is used. In the present case, photon pairs who share entanglement are used as a probe. From a spectroscopic point of view, the quantum properties of the entanglement can be used to offer a net advantage to quantum light over classical light. First, while exploring the different techniques proposed by the community, we will discuss many advantages offered by the quantum spectroscopy. Next, we will offer the theoritical tools required to the understanding of the entangled photons generation phenomenom, which is the spontaneous parametric down convertion. Then, we will discuss important features of the second order correlation function which are present in the entangled photons detection formalism. Important non classical spectral properties of the biphoton field will also be exposed. In addition, the experimental details about the building of a Hong-Ou-Mandel like interferometer, with a material to characterise in one of the arms, will be given. The interaction with the material will modify the biphoton properties, which will be visible in the anticorrelation dip caused by two-photon quantum interference. Despite the impossibility to measure the anticorrelation dip, because of the too low coupling of the photons in the interferometer, we observed entangled photon generation. Nevertheless, the possibility to observe two-photon interference as been shown by measuring quantum oscillations caused by one photon interference. This validate the possibility to use this technique as a material characterisation spectroscopic tool.

Keyphrases: Biphoton, Quantum spectroscopy, Spontaneous parametric down conversion, Entanglement, Quantum interference
Évolution des défauts dans les fibres optiques irradiées

The use of fiber Bragg grating as thermometers in space and radioactive environments requires a characterization of the optical defects created by cosmic rays, as well as their evolution under annealing.   The irradiation of the fibers by protons of 5 MeV have been carried out at different fluences between 109 cm--2 and 1015 cm--2 to reproduce the effect of cosmic rays predicted by the SPENVIS program. The fibers absorption measured by spectrometry showed the creation of new optical defects after a fluence of 109 cm--2. The main defects modifying the transmission in the fibers are E, D0, D and POR. At 3.5 eV, a photoluminescence band is created after a fluence of 109 cm--2. With a high-pass filter, it was possible to determine that this band was made by excited photoluminescence by a defect located at wavelenghts higher than 420 nm.  Tof-SIMS measurements confirmed the presence of chlorine in fibers, which creates an absorption band at 3.8 eV. This enables us to confirm the silica manufacturing method, which is used to make the optical fibers. The presence of germanium implies that there should be an absorption band ad 5.14 eV, but it is too weak to be observed by our measuring methods.  The annealing under nitrogen atmosphere carried out at 300°C, 500°C, 700°C and 900°C shows that the defect annealing is not characterized by a thermally activated process featuring a single activation energy, but occurs gradually over a wide temperature span, similar to what is observed during the relaxation of amorphous materials. Chlorine, POR and D0 defects have been observed at 900 °C.

Keyphrases: Absorption, Irradiation, Implantation, ToF-SIMS, Optical fibers, Annealing, Absorption band, Defects, Cosmic rays, Fiber Bragg gratings, Spectrometry