Graduate Theses & Dissertations

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Groundwater Recharge in a Managed Forest on the Oak Ridges Moraine, Southern Ontario
Groundwater recharge was estimated and compared in two open grasslands, three mixed deciduous forest stands (100+ years in age), three young red pine plantations (27 ¨C 29 years in age) and two old red pine plantations (62 ¨C 63 years in age) on the Oak Ridges Moraine, southern Ontario, Canada. Recharge was estimated using a 1-d water balance with measured precipitation, throughfall, stemflow, snowpack water equivalent and soil water storage, and modelled evapotranspiration. Throughfall distribution beneath red pine canopies showed no consistent variation with distance from the tree boles. Old red pines were not major stemflow producers and although the young red pines showed a slight tendency to focus stemflow (focussing ratio > 1), the inclusion of focussed stemflow when calculating recharge at the stand scale made little difference. Conversely, sugar maple (the predominant species in the mixed deciduous stands) showed a strong tendency to focus throughfall proximal to tree boles and produce large quantities of stemflow, resulting in relatively high soil moisture contents and enhanced opportunities for recharge within ~ 0.5 m of tree boles. Inclusion of these focussed inputs resulted in a ~ 11 ¨C 18 % increase in stand scale recharge estimates. The interpretation of land cover control on recharge was complicated by variations in soil texture between sites. Soil texture and its influence on soil water storage capacity resulted in temporal variations in recharge, with sites exhibiting large storage capacities producing less recharge in the fall and greater recharge in the spring than sites with limited storage capacities. Recharge estimates for the entire study period or seasonal values for sites grouped on the basis of soil water storage capacities showed a general trend of increasing recharge in the order: old red pine ¡Ö young red pine ¡ú mixed deciduous forest ¡Ö open grasslands. The disparity between the red pine plantations and the other sites was driven in large part by greater modelled evapotranspiration in the red pine plantations. The similarity in recharge between mixed deciduous forests and open grasslands was the result of focused inputs and less soil evaporation and transpiration in the mixed deciduous forests compared to the open grasslands. The results of this study suggest planting red pine on grasslands on the Oak Ridges Moraine will initially decrease recharge and this decrease will continue as the red pines mature. However, as the red pine plantations are succeeded by mixed hardwood stands recharge will recover to that of the initial grasslands. Author Keywords: Groundwater Recharge, Land Cover Type, Oak Ridges Moraine, Stemflow, Throughfall, Water Balance
Automated Grading of UML Class Diagrams
Learning how to model the structural properties of a problem domain or an object-oriented design in form of a class diagram is an essential learning task in many software engineering courses. Since grading UML assignments is a cumbersome and time-consuming task, there is a need for an automated grading approach that can assist the instructors by speeding up the grading process, as well as ensuring consistency and fairness for large classrooms. This thesis presents an approach for automated grading of UML class diagrams. A metamodel is proposed to establish mappings between the instructor solution and all the solutions for a class, which allows the instructor to easily adjust the grading scheme. The approach uses a grading algorithm that uses syntactic, semantic and structural matching to match a student's solutions with the instructor's solution. The efficiency of this automated grading approach has been empirically evaluated when applied in two real world settings: a beginner undergraduate class of 103 students required to create a object-oriented design model, and an advanced undergraduate class of 89 students elaborating a domain model. The experiment result shows that the grading approach should be configurable so that the grading approach can adapt the grading strategy and strictness to the level of the students and the grading styles of the different instructors. Also it is important to considering multiple solution variants in the grading process. The grading algorithm and tool are proposed and validated experimentally. Author Keywords: automated grading, class diagrams, model comparison
Cloud Versus Bare Metal
A comparison of two high performance computing clusters running on AWS and Sharcnet was done to determine which scenarios yield the best performance. Algorithm complexity ranged from O (n) to O (n3). Data sizes ranged from 195 KB to 2 GB. The Sharcnet hardware consisted of Intel E5-2683 and Intel E7-4850 processors with memory sizes ranging from 256 GB to 3072 GB. On AWS, C4.8xlarge instances were used, which run on Intel Xeon E5-2666 processors with 60 GB per instance. AWS was able to launch jobs immediately regardless of job size. The only limiting factors on AWS were algorithm complexity and memory usage, suggesting a memory bottleneck. Sharcnet had the best performance but could be hampered by the job scheduler. In conclusion, Sharcnet is best used when the algorithm is complex and has high memory usage. AWS is best used when immediate processing is required. Author Keywords: AWS, cloud, HPC, parallelism, Sharcnet
Identifying Indigenous Determinants of Health
The primary research question of this study was to explore the key factors influencing Indigenous health through an investigation of Inuit health in Nunavik. This research used an exploratory sequential mixed-methods design. The qualitative phase of this project employed interviews with Inuit health experts in Nunavik. The quantitative phase involved an analysis of the regional Inuit health dataset to identify predictors of Inuit self-rated health. Qualitative results identified a number of key social, cultural, environmental, and individual determinants of health in the region. Analysis of the quantitative data identified significant associations between variables such as age, physical activity, and peacefulness of the community and self-rated health. Considered in combination, the qualitative and quantitative results of this study indicate the potential value of determinants such as food security, education, and connection to land as important to Indigenous health. The analysis demonstrates that our understanding of health in an Indigenous context has to expand to include determinants beyond physical health. Author Keywords: determinants of health, Indigenous, Inuit, Nunavik, self-rated health
EXAMINING DREAMS, DREAM CONTENT, AND MEANING OF DREAMS IN BEREAVEMENT
Dreams that occur in bereavement have been mainly overlooked in the psychological literature. This study focuses on the most memorable dreams of the bereaved that contain imagery of the deceased. There were 52 participants who completed the study via email. The main goal of the study was to investigate the occurrence of common themes in the dreams that have the deceased as a character. It was hypothesized that the most memorable dreams are memorable because they positively influenced the dreamers waking life grief process, which was partially supported. Furthermore, it was expected that that the most memorable dreams will have a greater frequency of positive elements and a lower frequency of negative elements than the normative data on dreams, which was partially supported. These findings support past research on dreaming of the deceased and expand the impact that these types of dreams can have on the grief process. Author Keywords: bereavement, deceased imagery, dream content, dreams, grief
Seasonal habitat use and movement of native brook trout (Salvelinus fontinalis) in urban headwater streams
Coldwater streams are becoming increasingly impacted due to urbanization. Using environmental surveys, mark-recapture and telemetry, I assessed factors influencing seasonal brook trout (Salvelinus fontinalis) habitat use and movement in urban headwater streams in central Ontario between 2017-18. Generalized additive models were used to assess which habitat variables best explained seasonal yearling and older brook trout abundance, while generalized least squares models were used to assess overall trends in radio-tagged brook trout movement. My research demonstrated dynamic patterns in habitat use and movement by urban stream-dwelling brook trout. Yearlings were primarily influenced by water quality (stream temperature, conductivity), while older brook trout were most strongly influenced by stream morphology (depth, undercut bank). Movement occurred disproportionately around the spawning season and was more limited in the smaller, more altered stream. These findings may be used to inform fisheries managers on crucial timing and location of brook trout habitat refugia within urbanized environments. Author Keywords: Brook trout, coldwater stream, groundwater, habitat use, radiotelemetry, urbanization
Effects of Silver Nanoparticles on Lake Bacterioplankton
Silver nanoparticles (AgNP) released into aquatic environments could threaten natural bacterial communities and ecosystem services they provide. We examined natural lake bacterioplankton communities' responses to different exposures (pulse vs chronic) and types (citrate and PVP) of AgNPs at realistic environmental conditions using a mesocosm study at the Experimental Lakes Area. An in situ bioassay examined interactions between AgNPs and phosphorus loading. Bacterial communities exposed to high AgNP concentrations regardless of exposure or capping agent type accumulated silver. We observed increases in community production during additions of polyvinylpyrrolidone (PVP) -capped AgNPs and that site and nutrient-specific conditions are important to AgNPs toxicology in aquatic systems. Toxicological effects of AgNP are attenuated in natural conditions and differ from results from laboratory studies of AgNP toxicity. Our results demonstrate more studies are needed to fully assess the risk posed by these novel chemicals to the environment. This work could be useful in forming risk assessment policies which are largely based on lab studies and typically demonstrate strong toxic effects. Author Keywords: bacterial production, bacterioplankton communities, ecological stoichiometry, Experimental Lakes Area, mesocosms, silver nanoparticles
Observation-based assessment of atmospheric sulphur surrounding a major aluminum smelter in British Columbia, Canada
Recent developments at an aluminum (Al) smelter in Kitimat, BC resulted in a permitted increase of 27 to 42 tonnes of sulphur dioxide (SO2) emissions per day. Gaseous SO2 is a pollutant known to contribute to acidic deposition through processes of wet and dry deposition and can additionally react in-atmosphere to form particulate sulphate (pSO42-). Between June 2017 to October 2018, an extensive network consisting of ion exchange resin (IER) column, passive-diffusive, and active filter-pack samplers was established to provide an estimate of total annual S deposition and pSO42- variation throughout the Kitimat Valley. Filter-pack sampling determined the relative concentration of pSO42- increased downwind of the smelter. Comparison of observation-based and modelled total annual deposition suggested CALPUFF was accurate in representing the spatial viability of S deposition (R2 = > 0.85). However, the model appeared to overpredict near-field deposition suggesting the potential of underestimation further downwind of the smelter. Author Keywords: aluminum smelter, atmospheric deposition, filter-pack sampler, ion-exchange column sampler, pSO42-, SO2
Maya Exploitation of Animal Resources during the Middle Preclassic Period
This study examines the foraging strategies of animal resource exploitation during the Middle Preclassic period (900-300 BC) at the ancient Maya site of Pacbitun, Belize. The faunal remains analyzed in this study were recovered from various domestic structures associated with the production of shell artifacts. Detailed taphonomic analyses have revealed that the Pacbitun faunal remains were particularly affected by weathering and density-mediated attrition. White-tailed deer was the prey most frequently acquired by the Middle Preclassic Maya of Pacbitun, followed by other lower-ranked artiodactyls. A variety of less profitable prey were sometimes included in the diet breadth. Using the central place forager prey choice model as a framework, the analysis of diet breadth, habitat use, and carcass transport patterns suggests that most animal resources were acquired from terrestrial habitats, at short distances from the site. Complete carcasses of large game appear to have been frequently transported to the site, where they were exploited for their meat and marrow. Comparisons with other Middle Preclassic faunal assemblages indicate significant differences in terms of taxonomic composition, with an emphasis on the procurement of fish and turtles. It is suggested that the Middle Preclassic Maya adopted foraging strategies focusing on the exploitation of local habitats, with occasional use of exotic resources. Author Keywords: Animal, Belize, Foraging, Maya, Subsistence, Zooarchaeology
Effect Assessment of Binary Metal Mixtures of Ni, Cu, Zn, and Cd to Daphnia magna
Mixtures of metals occur in surface waters, toxicity of which has drawn world-wide attention due to their crucial role in both ecotoxicology and regulations. The present research was undertaken to study the acute toxicity of binary mixtures of Ni, Cu, Zn, and Cd to the freshwater organism, Daphnia magna. The experimental approach included single and binary metal toxicity tests based on the 48h acute toxicity bioassay of Environment Canada. The acute toxicity of single metals followed the order of Cd > Cu > Zn > Ni. Based on the calculated 48h EC50 value of single metals, a toxic unit (TU) approach was used to combine two metals in a binary mixture, in which 1TU was equal to the 48h EC50 value of a metal in single exposure. The toxicity of binary metal mixtures to D. magna followed the order of Cu-Cd > Cu-Zn > Zn-Cd > Cu-Ni > Zn-Ni > Cd-Ni, which demonstrated three types of toxicity (i.e., less than additive, additive, and greater additive). Predictions from additivity models (including concentration addition (CA) and independent action (IA) models), a generalized linear model (GLM), and a biotic-ligand-like model (BLM-like) were compared to the bioassay results. The CA and the RA models also predicted three types of toxicity of the binary metal mixtures (i.e., less than additive, additive, and greater than additive). However, the CA model mostly overestimated the toxicity of binary mixtures. Predictions from the GLM supported the inclusion of the interaction between two metals in a mixture to predict the toxicity of binary metal mixtures. The binary metal toxicity was also predicted using a BLM-like model based on the calculated concentrations of free ionic forms of the metals, affinity constants, and toxic potency of each metal. In this model, it was hypothesized that the toxicity of metal mixture is the result of competition of metals with Ca2+ at biotic ligands, which can lead to whole-body deficiency of Ca2+ in D. magna. The BLM-like model provided the toxic potency of single metals with the following order, Cu > Cd > Zn > Ni. Although the prediction of the BLM-like model was not in good agreement with the observed toxicity of binary metal mixtures, an overestimation of risk of mixture toxicity was obtained using this model, which could be promising for use in environmental risk assessment. Author Keywords: biotic ligand model, concentration addition, Daphnia magna, independent action, metal toxicity, modeling
Assessment of an adult lake sturgeon translocation (Acipenser fulvescens) reintroduction effort in a fragmented river system
North American freshwater fishes are declining rapidly due to habitat fragmentation, degradation, and loss. In some cases, translocations can be used to reverse local extirpations by releasing species in suitable habitats that are no longer naturally accessible. Lake sturgeon (Acipenser fulvescens) experienced historical overharvest across their distribution, leading to endangered species listings and subsequent protection and recovery efforts. Despite harvest and habitat protections, many populations do not appear to be recovering, which has been attributed to habitat alteration and fragmentation by dams. In 2002, 51 adult lake sturgeon from the Mattagami River, Ontario, Canada were translocated 340 km upstream to a fragmented 35 km stretch of the river between two hydroelectric generating stations, where sturgeon were considered extirpated. This study assessed the translocation effort using telemetry (movement), demographics and genetic data. Within the first year, a portion of the radio-tagged translocated individuals dispersed out of the release area, and released radio-tagged individuals used different areas than individuals radio-tagged ten years later. Catches of juvenile lake sturgeon have increased over time, with 150 juveniles caught within the duration of this study. The reintroduced population had similar genetic diversity as the source population, with a marked reduction in effective population size (Ne). The results indicate that the reintroduction effort was successful, with evidence of successful spawning and the presence of juvenile lake sturgeon within the reintroduction site. Overall, the results suggest adult translocations may be a useful tool for re-establishing other extirpated lake sturgeon populations. Author Keywords: conservation, endangered species, lake sturgeon, reintroduction, telemetry, translocation
Genre Trouble and Extreme Cinema
This dissertation re-evaluates theories of genre and spectatorship in light of a critic-defined tendency in recent art cinema, coined extreme cinema. It argues that the films of Mexican director Carlos Reygadas and French director Catherine Breillat expand our generic classifications and, through the re-organization of the visual presentation of genre-specific clichés and devices, their films transform sense experience and thought. My approach loosely follows Stanley Cavell’s various assertions of film as a medium of thought or, simply, that films think. Reygadas and Breillat allow spectators to reflect on the genre-film experience; I contend that their films make it apparent that genre is not established prior to the viewing of a work but is recollected and assembled by spectators in ways that matter for them. In fostering this experience of collection, these two directors propose a kind of ethics of curatorship: spectators are tasked with collecting and recollecting their film experience to generate particular social, cultural, and political critiques. To further accomplish and foster film as thought, the directors appeal to spectators’ sense experiences. I therefore deploy contemporary film theories on the senses, both phenomenological and affect theory, and partake in close readings of the films’ forms and narratives. The Introduction outlines my intervention in genre theory, discusses the key theoretical texts, develops the phenomenological framework I employ for the chapters to follow, develops my methodology through a description of Cavell’s style, and presents the stakes of my argument. Chapter one considers the place of experimental narrative cinema in Reygadas’s Post Tenebras Lux (2012). I argue that through his realist style, this film aims at an experience for spectators “as if” in a dream and through this film experience I posit the critique I find internal to the film. The second chapter turns to Catherine Breillat’s oeuvre and the confrontation her work poses to conceptions of pornography. I bring her 2001 feature Fat Girl (À ma soeur!) to bear on what I claim to be a new style of pornographic work and its challenge to patriarchy. The final chapter brings together Reygadas’s Battle in Heaven (Batalla en el cielo, 2005) and Breillat’s Sex is Comedy (2002) to accomplish an analysis of sexual performances in otherwise dramatic films. Author Keywords: art cinema, Carlos Reygadas, Catherine Breillat, contemporary cinema, film theory, genre theory

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Graduate student theses produced at Trent University. You may also browse theses and dissertations by year, program, or author.

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