Graduate Theses & Dissertations

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Effects of Silver Nanoparticles on Lower Trophic Levels in Aquatic Ecosystems
Due to their effective antibacterial and antifungal properties, silver nanoparticles (AgNPs) have quickly become the most commonly used nanomaterial, with applications in industry, medicine and consumer products. This increased use of AgNPs over the past decade will inevitably result in an elevated release of nanoparticles into the environment, highlighting the importance of assessing the environmental impacts of these nanomaterials on aquatic ecosystems. Although numerous laboratory studies have already reported on the negative effects of AgNPs to freshwater organisms, only a handful of studies have investigated the impacts of environmentally relevant levels of AgNPs on whole communities under natural conditions. This thesis examines the effects of chronic AgNP exposure on natural freshwater littoral microcrustacean, benthic macroinvertebrate and pelagic zooplankton communities. To assess the responses of these communities to AgNPs, I focused on a solely field-based approach, combining a six-week mesocosm study with a three-year whole lake experiment at the IISD – Experimental Lakes Area (Ontario, Canada). Our mesocosm study tested the effects of AgNP concentration (low, medium and high dose), surface coating (citrate- and polyvinylpyrrolidone [PVP]-coated AgNPs), and type of exposure (chronic and pulsed addition) on benthic macroinvertebrates in fine and stony sediments. Relative abundances of metal-tolerant Chironomidae in fine sediments were highest in high dose PVP-AgNP treatments; however, no negative effects of AgNP exposure were seen on biodiversity metrics or overall community structure throughout the study. I observed similar results within the whole lake study that incorporated a long-term addition of low levels of AgNPs to an experimental lake. Mixed-effects models and multivariate methods revealed a decline in all species of the littoral microcrustacean family Chydoridae in the final year of the study within our experimental lake, suggesting that this taxon may be sensitive to AgNP exposure; however, these effects were fairly subtle and were not reflected in the overall composition of littoral communities. No other negative effects of AgNPs were observed on the pelagic zooplankton or benthic macroinvertebrate communities. My results demonstrate that environmentally relevant levels of AgNPs have little impact on natural freshwater microcrustacean and benthic macroinvertebrate communities. Instead, biodiversity metrics and community structure are primarily influenced by seasonal dynamics and nutrient concentrations across both lakes. This thesis highlights the importance of incorporating environmental conditions and the natural variability of communities when examining the potential risks posed by the release of AgNPs into the environment, as simplistic laboratory bioassays may not provide an adequate assessment of the long-term impacts of AgNPs on freshwater systems. Author Keywords: Benthic macroinvertebrates, IISD - Experimental Lakes Area, Littoral microcrustaceans, Silver nanoparticles, Whole lake experiment, Zooplankton
cascading effects of risk in the wild
Predation risk can elicit a range of responses in prey, but to date little is known about breadth of potential responses that may arise under realistic field conditions and how such responses are linked, leaving a fragmented picture of risk-related consequences on individuals. We increased predation risk in free-ranging snowshoe hares (Lepus americanus) during two consecutive summers by simulating natural chases using a model predator (i.e., domestic dog), and monitored hare stress physiology, energy expenditure, behaviour, condition, and habitat use. We show that higher levels of risk elicited marked changes in physiological stress metrics including sustained high levels of free plasma cortisol which had cascading effects on glucose, and immunology, but not condition. Risk-augmented hares also had lowered daily energy expenditure, spent more time foraging, and decreased rest, vigilance, and travel. It is possible that these alterations allowed risk-exposed hares to increase their condition at the same rate as controls. Additionally, risk-augmented hares selected, had high fidelity to, and were more mobile in structurally dense habitat (i.e., shrubs) which provided them additional cover from predators. They also used more open habitat (i.e., conifer) differently based on locale within the home range, using familiar conifer areas within cores for rest while moving through unfamiliar conifer areas in the periphery. Overall, these findings show that prey can have a multi-faceted, highly plastic response in the face of risk and can mitigate the effects of their stress physiology given the right environmental conditions. Author Keywords: behaviour, condition, daily energy expenditure, predator-prey interactions, snowshoe hare, stress physiology
Instabilities in the Identity of an Artistic Tradition as "Persian," “Islamic," and “Iranian” in the Shadow of Orientalism
This dissertation is a critical review of the discursive formation of Islamic art in the twentieth century and the continuing problems that the early categorization of this discipline carries. It deals with the impact of these problems on the conceptualization of another category, Persian art. The subject is expounded by three propositions. First, the category of Islamic art was initially a product of Orientalism formulated regardless of the indigenous/Islamic knowledge of art. Second, during the early period when art historians examined different theoretical dimensions for constructing an aesthetic of Islamic art in the West, they imposed a temporal framework on Islamic art in which excluded the non-traditional and contemporary art of Islamic countries. Third, after the Islamic Revolution in 1979, Iranian scholars eventually imposed academic authority over the discipline of Persian/Islamic art, they adopted the same inadequate methodologies that were initially used in some of the early studies on the art of the Muslims. These propositions are elaborated by examples from twentieth-century Iranian movements in painting, The Coffeehouse Painting and The School of Saqqakhaneh, and the incident of swapping Willem de Kooning’s painting Woman III with the dismembered manuscript of the Shahnama of Shah Tahmasp in 1994. The conceptualization of Islamic art as a discipline is also discussed in relation to the twentieth-century cultural context of Iran. The argument is divided into three chapters in relation to three important historical moments in the history of contemporary Iran: The Constitutional Revolution (1905-1911), the modernization of Iran (1925-1975), and the Islamic Revolution (1979-onward). The formation of the discourse of Islamic art is the fruit of nineteenth-century Orientalism. Out of this discourse, Persian art as a modern discourse addressing the visual culture of Pre-Islamic and Islamic Iran came into being. I claim that after the Islamic Revolution, Iranian academics demonstrate a theoretical loyalty to the early theorizations of Islamic/Persian art. By this token, visual signs are given a meta-signified in the narrative of Islamic art. The ontological definition of this meta-signified is subjected to the dominant ideology, which determines how different centers of meaning should come into being and disappear. In the post-Revolution academia, the center is construed as the transcendental signified. Such inherence resulted in a fallacy in the reading of the Persian side of Islamic art, to which I refer as the “signification fallacy.” The dissertation draws on the consequences of this fallacy in the critique of Islamic art. Keywords: Persian art, Islamic art, Iranian art; Persian classical literature, Narrative. Image, Representation, Aniconism, Abstraction, Modernity, Tradition, Orientalism, The Constitutional Revolution, Modernization, The Islamic Revolution. Shahnama of Shah Tahmasp, The Coffeehouse Painting, The School of Saqqakhaneh; Modernism: Woman III. Author Keywords: Iranian Art, Islamic Art, Orientalism, Persian Art, The Constitutional Revolution, The Islamic Revolution
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
Following ininaahtigoog Home
Indigenous peoples’ sur-thrivance in global, settler colonial, historical, and nation-specific economic contexts is a broadly studied subject that fails to emphasize Indigenous economic sovereignty. Indigenous knowledges regarding the land-based relationalities which formulate an aspect of Indigenous economic sovereignty is lacking. So too is knowledge on Indigenous womxn’s land and water-based relationalities from which her economic sovereignty flows. Writing within and for Anishinaabeg sur-thrivance in Anishinaabewaki, this research examines Anishinaabeg womxn’s relationship with the sugar bush during the spring harvest as a site of gendered nation-specific economic sovereignty. Epistemicide has attenuated land-based knowledges in gendered ways; and, missionary and settler colonial processes in Canada, the U.S., and within Anishinaabeg communities have alienated Anishinaabeg womxn from inherent land and water-based relationships. By employing an Anishinaabeg methodology of “critically returning to ourselves” that is oriented towards Anishinaabe approaches to history and Anishinaabe ways of seeing history as worlds, this research recovers information about womxn’s sugar bush relationships. This recovery begins with literary, documentary, and oral sources. Through anishinaabe feminist interpretation, I reveal that womxn’s sugar bush relationships engender whole worlds that are animated and generated by her legendary connections with the natural and spiritual world, her social-economic commitment and savvy, and her enduring labour. I further interpret that her connections, her savvy, and her labour is mediated with variable aspects of settler colonial gendered influences such as patriarchy, omnipresent heterosexuality and/or gender binaries, marriage, class, and values attributed to womxn that are inconsequential to sur-thriving in land and water-based worlds. In conclusion this research tells three distinct, but connected, “sticky and sweet [story] strands” which illuminate the significance, beauty, complexity, and un-romance of Anishinaabeg womxn’s relationship with the sugar bush. Simultaneously, it prompts Anishinaabeg to reflect on the worlds we have lived in, are living in now, and want to create in terms of land-based relationships and relationalities. In effort to disrupt and bring attention to the restrictions and distortions that several hundred years of missionary, settler colonial, (hetero)patriarchal, heterosexist, and capitalist forces have had on Anishinaabeg gender and relational formations, my method in writing (i.e. spelling) is to prompt consciousness of gender and relational fluidity and diversity. This approach presses for Anishinaabeg committed orientation towards the necessities and possibilities of correcting and transforming imposed and internalized settler gender and relational formations and structures. This research builds on a body of literature about Indigenous womxn’s relationship with land and water in Turtle Island in order to signify and illuminate Anishinaabeg womxn’s dynamic and varied relationship with the sugar bush. It contributes to Indigenous research methodology, Indigenous and Anishinaabeg women’s history, Indigenous women’s labour, and Indigenous literary studies. Author Keywords: Anishinaabeg Studies, economic sovereignty, Indigenous feminism, Indigenous relationship with land, Indigenous women, sugar bush
Role of Dielectric Screening in SrTiO3-Based Interfaces
We build a theoretical model for exploring the electronic properties of the two-dimensional (2D) electron gas that forms at the interface between insulating SrTiO3 (STO) and a number of perovskite materials including LaTiO3, LaAlO3, and GdTiO3. The model treats conduction electrons within a tight-binding approximation, and the dielectric polarization via a Landau-Devonshire free energy that incorporates STO's strongly nonlinear, nonlocal, field-, and temperature-dependent dielectric response. We consider three models for the dielectric polarization at the interface: an ideal-interface model in which the interface has the same permittivity as the bulk, a dielectric dead-layer model in which the interface has permittivity lower that the bulk, and an interfacial-strain model in which the strain effects are included. The ideal-interface model band structure comprises a mix of quantum 2D states that are tightly bound to the interface, and quasi-three-dimensional (3D) states that extend hundreds of unit cells into the STO substrate. We find that there is a substantial shift of electrons away from the interface into the 3D tails as temperature is lowered from 300 K to 10 K. We speculate that the quasi-3D tails form the low- density high-mobility component of the interfacial electron gas that is widely inferred from magnetoresistance measurements. Multiple experiments have observed a sharp Lifshitz transition in the band structure of STO interfaces as a function of applied gate voltage. To understand this transition, we first propose a dielectric dead-layer model. It successfully predicts the Lifshitz transition at a critical charge density close to the measured one, but does not give a complete description for the transition. Second, we use an interfacial-strain model in which we consider the electrostrictive and flexoelectric coupling between the strain and polarization. This coupling generates a thin polarized layer whose direction reverses at a critical density. The transition occurs concomitantly with the polarization reversal. In addition, we find that the model captures the two main features of the transition: the transition from one occupied band to multiple occupied bands, and the abrupt change in the slope of lowest energy band with doping. Author Keywords:
Hybridization dynamics in cattails (Typha spp.,) in northeastern North America
Interspecific hybridization is an important evolutionary process which can contribute to the invasiveness of species complexes. In this dissertation I used the hybridizing species complex of cattails (Typha spp., Typhaceae) to explore some of the processes that could contribute to hybridization rates. Cattails in northeastern North America comprise the native T. latifolia, the non-native T. angustifolia, and their fertile hybrid, T. × glauca. First, I examined whether these taxa segregate by water depth as habitat segregation may be associated with lower incidence of hybridization. I found that these taxa occupy similar water depths and therefore that habitat segregation by water depth does not promote mating isolation among these taxa. I then compared pollen dispersal patterns between progenitor species as pollen dispersal can also influence rates of hybrid formation. Each progenitor exhibits localized pollen dispersal, and the maternal parent of first generation hybrids captures more conspecific than heterospecific pollen; both of which should lead to reduced hybrid formation. I then conducted controlled crosses using all three Typha taxa to quantify hybrid fertility and to parameterize a fertility model to predict how mating compatibilities should affect the composition of cattail stands. I found that highly asymmetric formation of hybrids and backcrosses and reduced hybrid fertility should favour the maintenance of T. latifolia under certain conditions. Finally, I used a population genetics approach to characterize genetic diversity and structure of Typha in northeastern North America to determine the extent to which broad-scale processes such as gene flow influence site-level processes. I concluded that hybrids are most often created within sites or introduced in small numbers rather than exhibiting broad-scale dispersal. This suggests that local processes are more important drivers of hybrid success than landscape-scale processes which would be expected to limit the spread of the hybrid. Though my findings indicate some barriers to hybridization in these Typha taxa, hybrid cattail dominates much of northeastern North America. My results therefore show that incomplete barriers to hybridization may not be sufficient to prevent the continued dominance of hybrids and that active management of invasive hybrids may be required to limit their spread. Author Keywords: fertility model, genetic structure, Hybridization, invasive species, niche segregation, pollen dispersal
Nineteenth-Century Aesthetics of Murder
This dissertation examines how sex crime and serial killing became a legitimate subject of aesthetic representation and mass consumption in the nineteenth century. It also probes into the ethical implications of deriving pleasure from consuming such graphic representations of violence. Taking off from Jack the Ripper and the iconic Whitechapel murders of 1888, it argues that a new cultural paradigm – the aesthetics of murder – was invented in England and France. To study the ‘aesthetics of murder’ as countless influential critics have done is not to question whether an act of murder itself possesses beautiful or sublime qualities. Rather, it is to determine precisely how a topic as evil and abject as murder is made beautiful in a work of art. It also questions what is at stake ethically for the reader or spectator who bears witness to such incommensurable violence. In three chapters, this dissertation delves into three important tropes – the murderer, corpse, and witness – through which this aesthetics of murder is analyzed. By examining a wide intersection of visual, literary, and cultural texts from the English and French tradition, it ultimately seeks to effect a rapprochement between nineteenth-century ethics and aesthetics. The primary artists and writers under investigation are Charles Baudelaire, Thomas De Quincey, Oscar Wilde, and Walter Sickert. In bringing together their distinctive styles and aesthetic philosophies, the dissertation opts for an interdisciplinary and comparative approach. It also aims to absolve these writers and artists from a longstanding charge of immorality and degeneracy, by firmly maintaining that the aesthetics of murder does not necessarily glorify or justify the act of murder. The third chapter on the ‘witness’ in fact, elucidates how writers like De Quincey and Wilde transferred the ethical imperative from the writer to the reader. The reader is appointed in the role of a murder witness who accidentally discovered the corpse on the crime scene. As a traumatized subject, the reader thus develops an ethical obligation for justice and censorship. Author Keywords: Censorship, Jack the Ripper, Murder, Trauma, Victorian, Wilde
Towards a Critical Pedagogy of Globality
In this thesis, I use “Trump’s Wall” between Mexico and the US to resist Eurocentrism and the challenges Eurocentric pedagogy poses to the research-practitioner. In my method, I reimagine C. Alejandra Elenes’ borderlands theory as a zone of empowerment within a multicultural Canadian classroom, and braid it in a hybrid assemblage with the rhizome. The “rhizo-borderlands” assemblage uses selected field notes gleaned from my teaching practice to develop themes of a critical pedagogy of globality in personal, local and international dimensions. These are further braided with a “day-in-the-life” narrative of a fictionalized student (Ellie) who navigates her way towards a world literature classroom where the focus is The Kite Runner by Khaled Hosseini. This assemblage affirms my belief that teaching and learning provides a context where students become “border crossers” and navigate points of intersection between their local and global selves, in order to develop intercultural competencies. Author Keywords: Action Narrative, Critical Pedagogy, Rhizomes
Supercritical Water Chemistry
Supercritical water (SCW) exhibits unique properties that differentiates it from its low temperature behaviour. Hydrogen bonding is dramatically reduced, there is no phase boundary between liquid and gaseous states, heat capacity increases, and there is a drastic reduction of the dielectric constant. Efforts are underway for researchers to harness these properties in the applications of power generation and hazardous waste destruction. However, the extreme environment created by the high temperatures, pressures and oxidizing capabilities pose unique challenges in terms of corrosion not present in subcritical water systems. Molecular Dynamics (MD) simulations have been used to obtain mass transport, hydration numbers and the influence on water structure of molecular oxygen, chloride, ammonia and iron (II) cations in corrosion crevices in an iron (II) hydroxide passivation layer. Solvation regimes marking the transitions of solvation based versus charge meditated processes were explored by locating the percolation thresholds of both physically and hydrogen bonded water clusters. A SCW flow through reactor was used to study hydrogen evolution rates over metal oxide surfaces, metal release rates and the kinetics for the oxidation of hydrogen gas by oxygen in SCW. Insights into corrosion phenomena are provided from the MD results as well as the experimental determination of flow reactor water and hydrogen chemistry. Author Keywords: Flow Studies, Molecular Dynamics, Supercritical Water
All Things Fusible
This dissertation presents the work of the American science fiction writer Neal Stephenson as a case study of mediations between literature and science by mobilizing its resonances with contemporary science studies and media theory. Tracing the historical and thematic trajectory of his consecutively published novels Snow Crash (1992), The Diamond Age; or, A Young Lady’s Illustrated Primer (1995), Cryptonomicon (1999), Quicksilver: The Baroque Cycle I (2003), The Confusion: The Baroque Cycle II (2004), and The System of the World: The Baroque Cycle III (2004), it approaches Stephenson’s fiction as an archaeology of the deep history of science that leads from late twentieth-century cyberculture, to world-war-two cryptography, and the seventeenth-century rise of the Royal Society. Refracted through a parallel reading of Stephenson’s novels and the theoretical work of Michel Serres, Bruno Latour, Friedrich A. Kittler, Isabelle Stengers, Donna Haraway, and others, this dissertation offers a literary discussion of the relations among cybernetics, complexity theory, information theory, systems theory, Leibnizian metaphysics, and Newtonian alchemy. Recognizing these hybrid fields as central to contemporary dialogues between the natural sciences and the humanities, Stephenson’s work is shown to exhibit a consistent engagement with the feedback loops among physical, artistic, narratological, and epistemological processes of innovation and emergence. Through his portrayal of hackers, mathematicians, natural philosophers, alchemists, vagabonds, and couriers as permutations of trickster figures, this dissertation advances a generalized notion of boundary transgressions and media infrastructures to illustrate how newness emerges by way of the turbulent con-fusion of disciplines, genres, knowledge systems, historical linearities, and physical environments. Uninterested in rigid genre boundaries, Stephenson’s novels are explored through the links among artistic modes that range from cyberpunk, to hard science fiction, historiographic metafiction, the carnivalesque, and the baroque. In a metabolization of the work performed by science studies, Stephenson’s fiction foregrounds that scientific practice is always intimately entangled in narrative, politics, metaphor, myth, and the circulation of a multiplicity of human and nonhuman agents. As the first sustained analysis of this segment of Stephenson’s work, this dissertation offers a contribution to both science fiction studies and the wider field of literature and science. Author Keywords: Complexity Theory, Cyberpunk, Michel Serres, Neal Stephenson, Science Fiction, Science Studies
Something out of Nothing? Place-based Resilience in Rural Canadian Youth
This dissertation explored how rural communities enhance the capacity of youth to both navigate and negotiate healthy identities and well-being in the context of social ecological resilience. Resilience refers to the capacity for individuals to have good outcomes in spite of exposure to significant adversity. Rural communities are often identified as places of deficit both in scholarly literature and in general social discourse which can constitute adversity. Given the importance of place as a social determinant of health, rural communities can have a notable impact on the positive development of adolescent identity and well-being of the youth that reside within them. Drawing on the concept of social ecological resilience which draws attention to the importance of environments and relationships to support development, this project engaged with high school aged adolescents (14 to 18 years old) from Haliburton County in Central Ontario. Leveraging mixed model methods, the project featured both quantitative and qualitative approaches. There were 63 participants (33 male, 28 female and 2 non-binary) for the quantitative phase of the research which made use of the Child and Youth Resilience Measure survey instrument. The second phase of the research was qualitative and featured 14 participants who engaged in six focus groups. The focus groups provided context specific awareness of place-based factors which participants found supportive in their development. The results indicated that while the overall resilience scores for the community were lower than the national average (t(62) = 3.20, p <0.01), some study participants found the community to be resilience bolstering. Specifically, participants recognized the importance of supportive people, an awareness of an enriched sense of community, and a powerful sense of the value of nature and the outdoors to be the most significant aspects for the development of their resilience. The results indicate that rural youth are not naïve to the complexity of their circumstances but are able to use their rural contexts to develop the capacity to negotiate and navigate towards healthy identities and well-being. Author Keywords: Adolescent, Place-based, Resilience, Rural, Social Ecological, Youth

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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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