Background: The causes of childhood brain tumors (CBT) are essentially unknown. Exposure to extremely low frequency magnetic fields (ELF-MF) (3-3000Hz) is an ubiquitous part of modern life. However, very few studies have investigated the possible effect of maternal occupational ELF-MF exposure on CBT and the available findings are inconsistent across studies. / Methods: We examined the role of maternal occupational exposure to ELF-MF shortly before and during pregnancy on the incidence of childhood brain tumors. A total of 548 incident cases and 760 healthy controls recruited between 1980 and 2002 from two Canadian provinces (Quebec and Ontario) were included and their mothers were interviewed. Tumors were classified as astroglial tumors, primitive neuroectodermal tumors (PNET), and other gliomas. Quantitative occupational ELF-MF exposure in microtesla units was estimated using individual exposure estimations or a job exposure matrix. We used three metrics to analyze exposure: cumulative, average, and maximum level attained. / Results: Using the average exposure metric measured before conception, an increased risk was observed for astroglial tumors (OR=1.5, and 95% CI=1.0-2.4). During the entire pregnancy period, a significantly increased risk was observed for astroglial tumors as well as for all childhood brain tumors with the average metric (OR=1.6, 95% CI=1.1-2.5 and OR=1.5; 95% CI=1.1-2.2, respectively). Based on job titles, a two-fold risk increase was observed for astroglial tumors (OR=2.3, 95% CI=0.8-6.3) and for all childhood brain tumors (OR=2.3, 95% CI=1.0-5.4) among sewing machine operators. / Conclusion: Results are suggestive of a possible association between maternal occupational ELF-MF exposure and certain brain tumors in their offspring. / Keywords: brain tumors, occupational exposures, maternal exposures, magnetic fields, childhood cancer, job exposure matrix

Three buildings in Montreal and three buildings in Vancouver were designed for different level of "ductility" according to the 1985 National Building Code of Canada and the 1984 Canadian Concrete Code. / Three full scale reinforced concrete specimens representing an exterior beam-column-slab subassemblage of the Montreal structure were tested in order to determine the behaviour of these components. The role of the spandrel beam in limiting the effective slab width and its role in transferring shear to the joint region was investigated. / Analytical procedures were developed in order to predict the responses of main structural components to the combined loading effects of axial load, moment and shear. In addition a hysteretic behavioural model was developed in order to account for strength and stiffness degradation as well as pinching of the hysteretic response. / The analytical procedures were then used to model the responses of the components of these buildings. Non-linear dynamic analyses were carried out on each building for a series of artificially generated accelerograms. The results of the tests as well as the results of the non-linear dynamic analyses enabled an assessment of the performance of different building designs and an assessment of current code requirements.

Snowbed vegetation contains both vascular plants and bryophytes. The latest snowbeds cover areas that are of predominantly, if not exclusively, bryophyte flora while the vascular plants are generally confined to the periphery of such late snowbeds. It is hypothesised that the exclusion of vascular flora from the snowbed core is the result of the shortened growing season generated by late-lying snow, which the bryophyte flora is better able to tolerate. The snowbed bryophytes cannot, however, tolerate the competition offered by the vascular flora in the peripheral areas from which they are absent. Data indicate that some of the bryophyte snowbed species are inhabiting optimal conditions in the snowbed core, rather than tolerating sub-optimal conditions. Adaptation and acclimation responses observed in peripheral vascular species indicate that these are inhabiting sub-optimal conditions in the snowbed periphery. The relationship between snow-lie and climate is examined, with to the construction and examination of a second hypothesis that snowbed loyalty in the Scottish Highlands is high, while duration of snow cover is variable. Snow-lie loyalty is the product of prevailing wind conditions, which are persistent and consistent in Scotland leading to consistency in late snowbed location, while the occurrence of mid-winter thaws at all altitudes makes duration of snow cover through accumulated snow depth much more variable. Increased zonal flow in winter has affected snow-lie in the Scottish Highlands, with a slight decrease in snow-lie duration in recent years. It is not clear whether this pattern applies to all altitudes and accumulations at higher levels, especially in the western Highlands, may be increasing as a result of steeper winter-time lapse rates. With late snowbed location varying very little, it is possible that the consequences of global warming may not necessarily mean an extinction of the late snowbed bryophytes in Scotland, which constitute an important part of Britain's montane flora.

No description available.

No description available.

Doctor of Philosophy / Department of Statistics / Gary Gadbury / Researches in the fields in science and statistics often go beyond the two-variable cause-and-effect relationship, and also try to understand what connects the causal relationship and what changes the magnitude or direction of the causal relationship between two variables, predictor(T) and outcome (Y). A mediator (Z) is a third variable that links a cause and an effect, whereby T causes the Z and Z causes Y. In general, a given variable may be said to function as a mediator to the extent that it accounts for the relation between the predictor and the outcome (Baron and Kenny, 1986). The initial question regards the appropriate characterization of a mediation effect. Most studies, when comparing one or more treatments focus on an average mediating effect. This average mediating effect can be misleading when the mediating effects vary from subject to subject in the population. The primary focus of this research is to investigate individual mediating effects in a population, and to define a variance of these individual mediating effects. A concept called subject-mediator (treatment) interaction is presented and its role in evaluating a mediator’s behavior on a population of units is studied. This is done using a framework sometimes called a counterfactual model. Some common experimental designs that provide different knowledge about this interaction term are studied. The subgroup analysis is the most common analytic approach for examining heterogeneity of mediating effects. In mediation analysis, situations can arise where Z and Y cannot both be measured on an individual unit. We refer to such data as terminal measures data. We show a design where a mediating effect cannot be estimated in terminal measures data and another one where it can be, with an assumption. The assumption is linked to the idea of pseudo-replication. These ideas are discussed and a simulation study illustrates the issues involved when analyzing terminal measures data. We know of no methods that are currently available that specifically address terminal measures data.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries / Department: Nuclear Engineering.

Photographic realism is an effective framework for communicating meaning. In other words, the purpose is to convey an idea--not, for example, to depict a landscape. Misuse of photographic images may arise from a photographer's deliberate attempt to imbue an image with the meaning he or she desires. Thus, we might question photography's objective nature, although this should not be confused with realism. The latter refers to the imitative or representational quality of the subject, the former refers to scientific validity or truth. The issue of objectivity suggests useful concepts for art education. First, this paper considers photographic realism--technique is not a primary concern. Second, procedures that can alter realism are made evident. By understanding and using these methods, a student can more successfully comprehend and alter the photographic message.

Mining has left many long-lasting effects, often negative. Mining continues to this day and questions persist; “what are the legacies of mining, to what extent do our approval and assessment processes consider these effects, are we learning from our past experiences and how can we amplify our learning?” To answer these questions I interviewed people from the mining community of Snow Lake, Manitoba as well as mining and assessment experts from across Canada. Data collected though document analysis and semi-structured interviews with 24 participants were analyzed using mining legacy, EA, and transformative learning frameworks. Results reinforce a suite of negative legacy effects identified in the literature. EA may be the best tool we currently have for long-term planning but data show it is unable to fully consider legacy effects. Learning is important for moving towards sustainability; however, a community’s economic dependence and mining friendly culture can act as barriers to learning. / May 2016