Graduate Theses & Dissertations


Modelling Depressive Symptoms in Emerging Adulthood
Depression during the transition into adulthood is a growing mental health concern, with overwhelming evidence linking the developmental risk for depressive symptoms with maternal depression. In addition, there is a lack of research on the protective role of socioemotional competencies in this context. This study examines independent and joint effects of maternal depression and trait emotional intelligence (TEI) on the longitudinal trajectory of depressive symptoms during emerging adulthood. A series of latent growth models was applied to three biennial cycles of data from a nationally representative sample (N=933) from the Canadian National Longitudinal Survey of Children and Youth. We assessed the trajectory of self-reported depressive symptoms from age 20 to 24 years, as well as whether it was moderated by maternal depression at age 10 to 11 and TEI at age 20, separately by gender. The results indicated that mean levels of depression declined during the emerging adulthood in females, but remained relatively stable in males. Maternal depressive symptoms significantly positively predicted depressive symptoms across the entire emerging adulthood in females, but only at age 20-21 for males. In addition, likelihood of developing depressive symptoms was attenuated by higher global TEI in both females and males, and additionally by higher interpersonal skills in males. Our findings suggest that interventions for depressive symptoms in emerging adulthood should consider development of socioemotional competencies. Author Keywords: Depression, Depressive Symptoms, Emerging Adulthood, Intergenerational Risk, Longitudinal, Trait Emotional Intelligence
Potential for Greenhouse Gas Emissions from Sediments of Agricultural Streams and Lake Erie
This thesis examines how dissolved organic matter quantity and quality and nutrients influence the flux potential of greenhouse gases (GHG) from sediments collected from streams across southern Ontario as well as Lake Erie. Sediments were collected and incubated in a laboratory setting where headspace gases and interstitial waters were analyzed. Results demonstrated that nutrients (dissolved organic carbon (DOC), total dissolved phosphorous (TDP) and total dissolved nitrogen (TDN)) were commonly significant predictors of CO2, CH4, and N2O fluxes, but spatial discrepancies were observed for the significance of DOM quality and sedimentary characteristics. Land use was not found to be directly related to gas flux potential. Different relationships were observed between the streams and lake, and between the basins of Lake Erie. Overall, results from this study suggest that sediments from freshwater systems have the potential to be sources of GHG, the degree of which depends on nutrient concentrations and DOM structure from watershed inputs. Author Keywords: dissolved organic matter, greenhouse gases, Lake Erie, nutrients, sediment, streams
Phytohormone-enhanced heavy metal responses in Euglena gracilis
Phytohormones, Cytokinin (CK) and Abscisic acid (ABA), are best known for controlling plant growth and stress responses; but they also mediate various developmental perspectives in alga. Yet, their mode of action in algal adaptive strategies to heavy metal responses, their involvement in orchestration of phytohormone crosstalk remain largely unknown and a molecular framework of phytohormone-controlled heavy metal uptake is absent. I found that three metals known globally to contaminate aquatic ecosystems, nickel (Ni), lead (Pb), and cadmium (Cd), cause changes in the levels of endogenous CKs, ABA, auxins, and gibberellins (GAs) in the green alga Euglena gracilis. Exogenous ABA or CK (trans-zeatin) alleviated metal toxicity through improved metal uptake efficiency and the regulation of the endogenous CKs activity profiles and GAs activity. This new evidence suggests that E. gracilis possesses functional phytohormone signals and metabolic pathways that are under metal stress response. Exogenously applied ABA or CK provoked the coordinated activation of metal uptake, likely via enhanced accumulation of metal binding compounds (i.e., proline, glycine, cysteine containing peptides), which are effective for metal sequestration. Using untargeted metabolomics analysis and functional annotation, this thesis further established that, CK and ABA modified pathways and metabolites, which were mainly involved in metal acclimation and resistance. These modified metabolites that were under the influence of phytohormones in algal cells growing under metal stress conditions were associated with: lipid pathways, riboflavin metabolism, biosynthesis of cofactors/vitamin, and carbohydrate metabolism. Bioactive secondary compounds (e.g., terpenoids, alkaloids, flavonoids, carotenoids) were also modified in algal cells treated with phytohormones. The present study highlights that ABA and CKs are important regulators of algal metal accumulation/acclimation strategies based on increased metal uptake, enhanced CK metabolism, regulation of hormonal crosstalk and regulation of some core cellular metabolism pathways, all of which improve metal uptake efficiency. Finally, our results suggest that ABA and CK form a novel strategy for metal bioremediation techniques and for sourcing microalgal value-added metabolites. Author Keywords: abscisic acid, cadmium, cytokinin, Euglena gracilis, lead, nickel
Effect of Carbon Source and Phytohormones on the in vitro Growth of Euglena Gracilis
Microalgae are a promising source of valuable compounds relevant to biofuels, biomaterials, nutraceuticals as well as animal and human nutriment. Unfortunately, low cell density and slow growth result in reduced economic feasibility. Heterotrophic cell culturing using an organic carbon source in lieu of light has proven to be an effective alternative to photobioreactors; however, further improvement may be possible with the addition of growth promoting phytohormones. In this thesis, growth and endogenous hormone profiles in heterotrophic cultures of Euglena gracilis were evaluated using glucose and ethanol as carbon sources. Cytokinin (CK) and abscisic acid (ABA) were quantified by HPLC-ESI-MS/MS and compared to culture growth dynamics. Exogenous phytohormones treatments were also conducted to determine if they may mitigate nutrient reduction and improve growth. Phytohormones CK and ABA were purified and analyzed at seven points along the growth curve in small scale (250 mL flasks, 100 mL working volume) cultures. Among the key findings was that ethanol cultures undergoing exponential growth, primarily synthesize freebase cytokinins (FBCKs) and methylthiol-cytokinins (MeSCKs), while not producing detectable levels of ABA. In exogenous studies, dry biomass was positively influenced with the addition of exogenous ABA; however, the most notable result revealed the ability of transZ to alleviate nutrient reduction. These findings suggest a communication network in algal culture using FBCKs and MeSCKs, as well as the potential for exogenous hormone supplementation to increase growth rates and overall biomass productivity. Author Keywords: abscisic acid, cytokinin, Euglena gracilis, heterotrophy, phytohormones
Autobiographical Graphics
This thesis examines the work of queer women who author graphic autobiographical texts. Alison Bechdel, Sarah Leavitt, and Elizabeth Beier all employ the graphic medium to narrate their personal experiences with coming out, growing up, and navigating heteronormative spaces as lesbian or bisexual women. By studying the work of these three authors in tandem, this thesis functions to expand the archive of queer life by demonstrating that, even as queer life is made tangible in autobiographical writings, the ephemerality that marks the archives of queer life persists. Using feminist and queer theories, the study of abjection, archival studies, genre studies, and post-structuralist approaches to comics literatures, this thesis examines the body of the text, the body of the archive, and the bodies of the women that are contained within these structures to determine that queer women are creating a new tradition in graphic life writing. Author Keywords: archive, genre, graphic text, lesbian, queer, women
Habitat Characteristics, Density Patterns and Environmental Niches of Indo-Pacific Humpback Dolphins (Sousa chinensis) of the Pearl River Estuary and Eastern Taiwan Strait
The purpose of this thesis is to quantify the habitat characteristics, density patterns and environmental niches of two groups of Indo-Pacific humpback dolphins: Chinese white dolphins (CWD) of the Pearl River estuary (PRE), and Taiwanese white dolphins (TWD, =Taiwanese humpback dolphin, THD) found in the eastern Taiwan Strait (ETS). Much work has already been done on the habitat use of CWDs in parts of the PRE, so the purpose of my first two chapters was to advance knowledge of the TWD to a comparable level. Chapter 2 contains the first published description of the relatively shallow, inshore, estuarine habitat of the TWD. General environmental characteristics and observed group sizes were consistent with other populations of humpback dolphins, and group sizes were not correlated with the environmental variables measured during surveys. Chapter 3 investigated density patterns of TWDs, finding spatiotemporal heterogeneity across the study area. Humpback dolphin densities fluctuated from year to year, but some parts of the study area were consistently used more than others. Environmental characteristics again did not influence dolphin densities, though more dolphins than expected were sighted in waters adjacent to major land reclamations, which may be related to the location of these areas close to major rivers. In Chapter 4, niches of the TWD and CWDs found in the PRE were compared using species distribution models, which indicated significant niche overlap. This may be due to niche conservatism maintaining similar fundamental niches between the two groups since their historical split >10,000 years ago, or a result of the intrinsic biotic factors that influence occurrence data affecting the hypervolume dimensions of each realized niche in similar ways. Geographic predictions indicate that most of the TWD’s range has likely been surveyed, and that there may be connectivity between PRE humpback dolphins and at least one neighbouring putative population due to continuous predicted suitable habitat in waters that remain poorly surveyed. Overall, my thesis demonstrates that density patterns may vary over time, but on a broad temporal scale, these two allopatric groups of Indo-Pacific humpback dolphins have similar habitat requirements in geographically isolated, but environmentally similar locations. Author Keywords: density, habitat, Indo-Pacific humpback dolphin, niche overlap, Sousa chinensis, species distribution model
Temporo-spatial patterns of occupation and density by an invasive fish in streams
Since its introduction to North America in the 1990s, the Round Goby has spread throughout the Great Lakes, inland through rivers and is now moving into small tributary streams, a new environment for this species in both its native and invaded ranges. I explored density and temporal occupation of Round Gobies in four small streams in two systems in south-central Ontario, Canada in order to determine what habitat variables are the best predictors of goby density. Two streams are tributaries of Lake Ontario and two are tributaries of the Otonabee River, and all of these streams have barriers preventing upstream migration. I found that occupation and density differed between the systems. In the Otonabee River system, Round Gobies occupy the streams year round and the most important factor determining adult density is distance from a barrier to upstream movement, with the entire stream occupied but density highest next to the barriers. In the Lake Ontario system, density is highest at mid-stream and Round Gobies appear to occupy these streams mainly from spring to fall. Adult density in Lake Ontario tributaries is highest in sites with a high percentage of cobble/boulder and low percentage of gravel substrate, while substrate is less important in Otonabee River tributaries. Occupation and density patterns may differ due to contrasting environmental conditions in the source environments and distance to the first barrier preventing upstream movement. This study shows diversity in invasion strategies, and provides insight into the occurrence and movement patterns of this species in small, tributary streams. Author Keywords: biological invasion, Generalised Additive Mixed Model, habitat, Neogobius melanostomus, Round Goby, stream
Alien Imaginaries
This dissertation offers a cultural analysis of UFOs and extraterrestrials in the United States. In it I look at what I call real aliens — extraterrestrials believed to be real and interacting with humans on Earth. Beliefs in real aliens are often denigrated and dismissed in official discourse, yet they continue to not only persist, but thrive, in American society. Hence, this dissertation asks: Why do so many people believe that extraterrestrials are visiting our planet? Part One begins by tracing the invasion of real aliens in the United States using Orson Welles’s 1938 radio broadcast “The War of the Worlds” as a starting point. Here, I look at how and why the broadcast registered with listeners’ anxieties and created a fantastic and uncanny effect that made it possible for some to conceive of aliens invading the United States. In Part Two, I trace the rise of ufology, which involves the study of extraterrestrials currently interacting with humans on Earth, and I consider how the social and political climate of the Cold War, as well as the cultural environment of postmodernity, provided the necessary conditions for stories about aliens to be made believable. Part Three explores the case study of the Roswell Incident, a conspiracy theory about the origins of an alleged flying saucer crash and government cover-up. I look at the reasons for why many individuals have come to believe in this conspiracy theory and I reflect on the tensions between “official” and “unofficial” discourses surrounding this case. I also consider how and why Roswell has become such an important site for ufology, and I examine the performances given by ufologists at the annual Roswell International UFO Festival to appreciate how ufologists offers seductive explanations of why things are the way they are; for many, their stories offer a better version of events than the purely rational and positivist explanations offered by official sources, especially since they tap into the disillusionment and mistrust that many Americans feel about contemporary politics. Author Keywords: aliens/extraterrestrials, America, conspiracy, official and unofficial, storytelling, ufology
collaborative ecotoxicological risk assessment of in-place pollutants in Owen Sound Bay, Lake Huron within the Saugeen Ojibway Nation Territory
Owen Sound Bay, which is located within the traditional territory of the Saugeen Ojibway Nation (SON), is contaminated as a result of historical industrial and shipping activity. Gross contamination of the sediments in the inner part of the Bay (i.e., Owen Sound Harbour) includes high concentrations of polycyclic aromatic hydrocarbons (PAHs) and other organic compounds, as well as metals that may pose a risk to the SON fishery for lake whitefish (Coregonus clupeaformis). However, evaluating the environmental risks posed by contaminated sediments is a challenge, as these risks are dependent upon several factors and require multiple lines of evidence. Including Indigenous communities in environmental risk assessment and the management of those risks is vital for sustaining ecosystem integrity, as well as respecting Treaty Rights. In this study, a risk assessment framework was developed that included several risk assessment tools used in Western science and also encompassed the concerns and values of the SON, including the application of SON-ecological knowledge. Methods for risk evaluation included gathering lines of evidence though community workshops, as well as field sampling in the Bay to determine the concentrations of PAHs and other organic contaminants in sediments and in the water column. Laboratory studies of toxicity to early life stages of lake whitefish and Japanese medaka (Oryzias latipes) and sediment disturbance simulations to evaluate biological responses in juvenile lake whitefish were also completed as lines of evidence. The results indicate that leaving the harbour “as is” without a thorough analysis of remediation options fails to address the concerns of the people within the SON communities. Overall, this research demonstrated a successful process for developing a collaborative risk assessment framework that recognizes the sovereignty of Indigenous peoples and promotes Nation-to-Nation decision making. Author Keywords: biomarkers, Coregonus clupeaformis, Indigenous knowledge, polycyclic aromatic hydrocarbons, risk assessment, source tracking
Experiences of Five Undergraduate Academic Advisors in Ontario Universities
This study used qualitative research methods to develop an understanding of the landscape of undergraduate academic advising in Ontario universities as well as deeply explore the experiences and practices of five full-time academic advisors. Phase one of the study consisted of a document analysis of Ontario universities' public-facing websites. Phase two of the study consisted of five interviews with five undergraduate academic advisors from four Ontario institutions. The findings of the study demonstrated a variable landscape of academic advising across universities with responsibilities of advising ranging from solely course selection to a much broader role inclusive of helping students navigate their educational journey. Additionally, a relationship between external influences including institutional mission and organizational structure, and internal influences including advisors’ values, beliefs, and theoretical knowledge was identified. This relationship informed current advising strategies. These findings were used to develop a praxis of academic advising as well as five promising practices. Author Keywords: Academic Advising, Practice of Advising, Strategies of Advising, Universities
Forensic Epistemology
Forensic epistemology is the study of knowledge as it relates to forensic science and can be broken into four sources; intuitive, authoritative, logical and empirical. In a four-phase research approach, I explored reasoning skills (logical knowledge) used by crime scene experts and methods (empirical knowledge) for forensic case-specific experimentation. First, the reasoning skills of crime scene investigators (CSI) and bloodstain pattern analysts (BPA) were tested, correlated to demographics and reasoning categories were compared. Practitioner’s with graduate level education performed better on the reasoning test, however, significant differences were not found between test scores and years of experience. Similarly, there was no difference between test scores and employment status (specifically, police or civilian employees), for the CSI group nor within the BPA group. This information suggests that level of education plays the most important role in the development and use of reasoning skills, whereas experience and employment status are not as influential. Second, I investigate potential strategies in selecting data types for case-specific experimentation in pattern-interpretation disciplines within forensic science. I also examined the epistemic status of practitioner case experimentation in forensic science. Practitioners were more confident in a mixed-method approach when conducting case-specific experimentation. In addition, there is a knowledge gap in experimental design for some forensic practitioners. Third, is a reprint of the introductory section of my published book entitled The Scientific Method in Forensic Science: A Canadian Handbook that abridges knowledge gained from this dissertation with further evidence-based literature review and experiential examples. This phase summarizes the scientific method in forensic science and provides guidance for forensic science students and practitioners. The final phase merges the findings from the primary studies with a literature review; offering scientific evidence supporting suggested research and pedagogic strategies that can help increase the epistemic status of forensic science. Author Keywords: case-specific research, epistemology, forensic science, hypothetico-deductive reasoning, logic, research models
Differential expression of cytochrome b5s in Giardia intestinalis during nitrosative stress and encystation
The waterborne protozoan Giardia intestinalis cycles between the environmentally-resistant and infectious cyst and the metabolically-active trophozoite that adheres to the epithelial lining of the small intestine. Adhesion can trigger the innate immune response in epithelial cells, including the synthesis of the free radical nitric oxide (NO) that inhibits cell proliferation and encystation of trophozoites. In this work changes in protein expression of three Giardia isotypes of the redox heme protein cytochrome b5 (gCYTb5 I, II and III) were studied in response to either nitrosative stress or induction of encystation. Two nitrosative stressors, sodium nitrite and the NO donor DETA-NONOate, were used at sub-lethal concentrations (0.5 mM and 0.05 mM, respectively) that do not affect cell proliferation until later time points so that subtle changes in protein expression could be observed in the absence of other confounding factors. Nucleolar gCYTb5-I and nucleoplasmic gCYTb5-III expression patterns were similar in trophozoites exposed to either stressor, showing gradual increases in expression with peaks between 4 and 12 hours, which indicates these cytochromes respond to nitrosative stress and possibly to potential DNA damage in Giardia. In contrast, gCYTb5-II of the peripheral vacuoles, which are part of the endocytic pathway of Giardia, showed little change in expression in response to either stressor. However, changes in gCYTb5-II expression were observed in encysting trophozoites, with a 1.4-fold increase in protein levels at seven hours after induction of encystation, followed by a gradual decrease in expression. These changes are consistent with previous mRNA analysis done in our laboratory and suggest a role for gCYTb5-II in the increase in nutrient uptake during early encystation. Author Keywords: cytochrome, encystation, Giardia, heme, nitrosative, parasite


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