Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Cryptococcus neoformans is among the most common human pathogenic fungi and the leading cause of fungal meningitis. It consists of two divergent haploid serotypes A and D, as well as their hybrid serotypes AD. Hybridization between the two serotypes A and D is a widespread phenomenon in natural populations of this species. Studies have shown that serotype AD strains possess unique properties in several medically important traits: they are more virulent in animal models, more tolerant to antifungal drugs, more tolerant to UV radiation and other stresses than one or both parental serotypes. Despite the potential medical and evolutionary importance, relatively little is known about the phenotypic and genotypic consequences of the hybridization in C. neoformans. In my thesis, I present a series of studies that show: (1) recombination occurs at a very low frequency during hybridization between serotypes A and D; (2) serotypes A and D in C. neoformans have diverged from each other not only at the DNA sequence level, but also at the chromosomal structure level, both of which contributed to suppressed recombination and limited genetic introgression between the two serotypes; (3) though there is widespread hybridization, the hybrids seemed largely distinct and the genomes of the parental serotypes A and D populations are relatively unaffected by the hybrids in natural populations; and (4) the fixation of these serotype specific chromosomal rearrangements in the two serotypes, together with evidences of selective sweeps observed at both inversion junctions and genes located close to chromosomal inversions suggest that these rearranged regions (or genes surrounding these regions) were likely involved in the diversification between the two serotypes. My studies provide a genetic framework for future quantitative analyses of medically important traits of C. neoformans. / Thesis / Doctor of Philosophy (PhD)

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Background: Diastasis rectus abdominis (DRA) is a separation of the rectus abdominis during and after pregnancy. Physiotherapy is the first choice of intervention but it is unclear which type of training is the most effective.  Purpose: The aim of the study was twofold. The aim of the first part was to evaluate the effects of training the rectus abdominis in women with DRA postpartum. The aim of the second part was to describe how these women experienced this training program.  Method: Three women were included in the study. Firstly a single subject experimental design with A-B design was implemented. Inter-recti distance (IRD), activity impairment, muscle strength and endurance, pain and aesthetics was measured. Secondly a qualitative design was carried out to describe the participants' experiences. It was implemented with interviews analyzed with qualitative content analysis.  Results: Two of the participants got significantly decreased IRD. One of the participants got significantly improved in the activity impairment ´getting up from lying down with and without a weight´. There was no improvement in the other outcome measures. Two categories comprised by two subcategories each were identified by the qualitative analysis: positive and motivating experiences of the training and experiences of positive results of the training. The categories reveal positive experiences of the training design and exercises as well as becoming stronger and gaining trust to use the body again as the main result after the training period. Conclusion: An individually designed training program focusing on the rectus abdominis muscle could be effective for reducing the IRD and getting stronger when getting up from lying down in women with DRA 2-12 months postpartum. Training the rectus abdominis with regular supervision was experienced positively and motivating after pregnancy. The most important experienced result was becoming stronger and gaining increased trust in the body.

This work pioneers the experimental acquisition of data relating to the heating effects of inter-bar currents and the frequency components of the main field rotating flux. Previous research in the field of inter-bar currents is reliant on theory and mathematical modeling. Yet, with the growing need for increasing machine efficiency; experimental application of conceptualized theoretical models of machine losses is paramount. Focusing specifically on inter-bar currents in a rotating stator induction machine revealed a correlation between the heat generated in the iron core and the presence of inter-bar currents. Using temperature sensing instrumentation, experimental data was gathered to determine the inter-bar current distribution along the length of the rotor bars during acceleration. Additionally, custom current transducers were implemented to directly measure the main field rotating flux. The results present a solid foundation for direct and indirect measurement of inter-bar currents. / Thesis / Master of Applied Science (MASc)

Diameter distributions of juvenile loblolly pine (Pinus taeda L.) with different planting densities were characterized utilizing a two-parameter Weibull distribution. Trend analysis was employed to describe the effects of planting density, age, relative spacing, and rectangularity on the estimated diameter distributions for juvenile loblolly pine. A reparameterization of the two-parameter Weibull distribution was sought to reduce the dispersion of the estimated shape parameter. Methods that quantify the amount of inter-tree spatial dependency in a particular stand were applied. Empirical semivariograms were derived for each plot over all ages to enable spatial trend recognition. Moran's I and Geary's C coefficients were estimated for ground-line diameters from ages 2 to 5, and for breast height diameters from ages 5 to 11. Though there was no discernable trend in the presence of significant spatial autocorrelation with planting density, an initial negative trend with age was present, but leveled off by age 5. A conditional autoregressive model was utilized to evaluate the amount of spatial influence stems in a stand have on one another. The occurrence of significant spatial influences was positively associated with age through age 8, the trend then leveled off; no recognizable trend was detected with planting density. These indices help to describe stand dynamics that are influenced by the spatial distribution of stems. Models to predict the parameters of the two-parameter Weibull distribution were developed to aid in forecasting and simulation of juvenile loblolly pine. Simulations were conducted where a spatial dependency was imposed on the diameters within a stand. The spatial structure simulation enables accurate representations of stem characteristics when simulating forest stands that include spatially-explicit information. / Ph. D.