Graduate Theses & Dissertations

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Racism in Argentina and the Blackness Problem. The Change in Perception of Afro-Descendants in Buenos Aires and the New Dimensions of Blackness in Argentina (1880-1930)
This thesis examines racism in Argentina between 1880 and 1930. The governing elite's efforts to whiten the Argentine population at the end of the nineteenth century led to the erasure and discrimination of anyone who did not have Caucasian features: Afro-descendants, mulattos, mestizos, and creoles. However, in the 1930s, whitening policies proved to have limited success. On the one hand, Afro-descendants were praised by the middle and lower classes of Buenos Aires; on the other hand, the Great Depression's effects made it clear that the Argentine population was made up of an ethnic mixture that had much darker skin tones than the whitening elite preferred. This work will show how the impact of the 1930s global crisis, as well as the enthusiasm for Afro-descendants, reinforced the racism that still existed, and will demonstrate that blackness became more than a racial but also a class connotation. Author Keywords: Afro-descendants press, Blackness in Argentina, Buenos Aires Press, Cultural Constructions, Popular Blackness, Racial Identity
mechanistic analysis of density dependence in algal population dynamics
Population density regulation is a fundamental principle in ecology, however there remain several unknowns regarding the functional expression of density dependence. One prominent view is that the patterns by which density dependence is expressed are largely fixed across a species, irrespective of environmental conditions. Our study investigated the expression of density dependence in Chlamydomonas reinhartti grown under a gradient of nutrient densities, and hypothesized that the relationship between per capita growth rate (pgr) and population density would vary from concave-up to concave-down as nutrients became less limiting. Contrary to prediction, we found that the relationship between a population's pgr and density became increasingly concave-up as nutrient levels increased. Our results suggest that density dependence is strongly variable depending on exogenous and endogenous processes acting on the population, implying that expression of density regulation depends extensively on local conditions. Population growth suppression may be attributable to environments with high intraspecific competition. Additional work should reveal the mechanisms influencing how the expression of density dependence varies across populations through space and time. Author Keywords: Chlamydomonas reinhartti, density dependence, logistic model, population dynamics, single species growth, theta-logistic equation
Asserting sexual (dis)interest
Sexual assertiveness encompasses skills in refusing unwanted sexual situations and bringing about wanted sexual situations. Measures of sexual assertiveness typically assess both refusal and initiation aspects, yet there is a dearth of research examining these skills in relation to one another. The present study examined the relationship between these skillsets in women, exploring predictors of each. Initiation and refusal assertiveness were moderately correlated. Additionally, the relationship between them was not entirely explained by general assertiveness, indicating that there is something unique to assertiveness in the sexual context. Committed relationship context and erotophilic disposition specifically predicted initiation assertiveness. Less endorsement of the sexual double standard and fewer approach motivations for engaging in unwanted sex specifically predicted refusal assertiveness. Few differences emerged in predictors of assertiveness types when comparing sexual orientation groups, yet non-heterosexual women reported slightly lower levels of refusal assertiveness. Implications for sexual education, therapy, and future research are discussed. Author Keywords: sexual assertiveness, sexual autonomy, sexual compliance, sexual double standard, sexual satisfaction, sexual self-disclosure
Enhancing post-mortem interval estimates
The growth of immature insects that develop on human remains can be used to estimate a post-mortem interval (PMI). PMI estimate confidence is negatively affected by: larval killing and preservation methods altering their size, limited morphological parameters to assess larval growth and therefore age, and few available alternate species development data. I compared live specimens to preserved specimens of the same development stages to assess the effects of killing-preservation techniques on morphology, and I introduce a new method that uses digital photography to examine maggot mouthparts for stage grading of Phormia regina. Digital photographic methods enable live insects to be quantified and improve approximations of physiological age. I then use these digital methods to produce a growth-rate model for a beetle commonly found on human remains, Necrodes surinamensis, providing data for PMI estimates that was previously unavailable. Author Keywords: Forensic Entomology, Insect development, Morphometrics, Necrodes surinamensis, Phormia regina, Postmortem interval
Thinking High When Feeling Shy
Social anxiety often co-occurs with substance use disorders – various psychological variables, contextual factors, and implicit cognitions may help explain their relationship. This thesis examined whether social anxiety and psychological variables (jointly and independently) helped predict substance use and related problems. It also explored whether social anxiety group membership helped predict implicit cannabis-sedation associations and substance use desirability. A sample of undergraduate student volunteers (N = 65) completed a computer task, questionnaires with anxiety-provoking vignettes, and online questionnaires. Results indicate that fear of negative evaluation and anxiety sensitivity are important predictors of alcohol and cannabis (respectively) use and problems. Social anxiety group was related to increased cannabis desirability in performance contexts. No significant implicit cannabis-sedation associations were identified. Our findings highlight the importance of certain variables in social anxiety and substance use relationships, and considering contextual factors when assessing substance desirability. It also provides preliminary evidence of a novel implicit cannabis-sedation measure. Author Keywords: Coping, Emotion, Implicit Cognition, Social Anxiety, Substance Use
Situating Copper Bells in Prehispanic Southwest Societies
This thesis examines the spatial, temporal, and contextual distribution of copper bells in the Greater Southwest region and how they are situated in archaeological literature. To date, 672 copper bells have been found in at least 113 different Southwestern sites dating from ca. A.D. 900-1450, though there is no archaeological evidence for metallurgical activities in the area at this time. The origin of copper bells has been assumed to be West Mexico, a region known for its metallurgical traditions and whose inhabitants produced copious amounts of similar bells. Various lists of copper bells discovered have been compiled over the years, but little consideration has been given to the role these artifacts may have played in Southwestern societies. Copper bells are frequently labelled as prestige goods in archaeological literature, a term which fails to account for their significant depositional variation. By updating the database of known Southwestern copper bells, it becomes possible to examine these contextual distributions in greater detail. It is concluded that the prestige goods model is not suitable for Southwestern copper bells in many cases, and that alternative frameworks such as inalienable possessions are a better fit for these artifacts. Author Keywords: Archaeology, copper bells, inalienable possesions, interaction, U.S. Southwest
Balance is key
While preferences for symmetry are seemingly universal, they can be seen at their most extreme among individuals high in trait incompleteness. As yet, it is unclear why incompleteness yields heightened symmetry preferences. Summerfeldt et al. (2015) speculated that individuals high in incompleteness may develop heightened preferences for symmetry due to its greater perceptual fluency. Accordingly, the aim of the present set of three experiments was to examine this relationship. Implicit preferences for symmetry were measured using a modified version of the Implicit Association Test (IAT) reported by Makin et al. (2012). Experiments 1 (N = 24) and 2 (N = 24) examined whether the general implicit preferences for symmetry and influence of perceptual fluency reported by Makin et al. (2012) extended to a within-subjects design. Experiment 3 (N = 86) examined whether trait incompleteness is related to greater implicit preferences for symmetric stimuli, and whether perceptual fluency affects this association. Results showed that incompleteness and implicit preferences were related, and that incompleteness-related differences in preferences were eliminated when the patterns were equally perceptually fluent, supporting the idea that incompleteness-related preferences for symmetry are linked to perceptual fluency. Implications of these findings are discussed. Author Keywords:
Utilizing Class-Specific Thresholds Discovered by Outlier Detection
We investigated if the performance of selected supervised machine-learning techniques could be improved by combining univariate outlier-detection techniques and machine-learning methods. We developed a framework to discover class-specific thresholds in class probability estimates using univariate outlier detection and proposed two novel techniques to utilize these class-specific thresholds. These proposed techniques were applied to various data sets and the results were evaluated. Our experimental results suggest that some of our techniques may improve recall in the base learner. Additional results suggest that one technique may produce higher accuracy and precision than AdaBoost.M1, while another may produce higher recall. Finally, our results suggest that we can achieve higher accuracy, precision, or recall when AdaBoost.M1 fails to produce higher metric values than the base learner. Author Keywords: AdaBoost, Boosting, Classification, Class-Specific Thresholds, Machine Learning, Outliers
Retrograde Amnesia of Fear Memories Following Pentylenetetrazol Kindling
Memories pertaining to fearful events are some of the most salient and long-lasting memories, as they are critical to the survival of an organism. Seizures induce aberrant changes within temporal lobe and limbic brain structures that are critical for supporting fear memories. Seizures can occur at any time; therefore, it is imperative that research address how seizures impact previously learned information. The present series of experiments demonstrate that pentylenetetrazol-kindling induces retention deficits of previously acquired context fear memories in male rats. Kindling induced subsequent fear learning deficits but did not impact spatial learning. Additionally, following kindling, volumetric increase was observed within the hippocampal subfield CA3, as well as increased neural activation within the hippocampal subfield CA1. The results of this work suggests that chronic seizures can alter the function of neural networks important for supporting and retrieving previously acquired memories. Author Keywords: amygdala, anterograde amnesia, context fear conditioning, hippocampus, retrograde amnesia, seizures
Making eDNA count
Environmental DNA (eDNA) is rapidly becoming an established method for the detection of species in aquatic systems and has been suggested as a promising tool to estimate species abundance. However, the strength of the relationship between eDNA concentrations and taxon abundance (density/biomass) can vary widely between species. I investigated the relationship between eDNA concentration and species abundance using two common and closely-related amphibians in eastern North America, the wood frog (Rana sylvatica) and northern leopard frog (Rana pipiens). I manipulated tadpole density in 80 L mesocosms and documented the relationship between tadpole density, biomass, and eDNA concentration. Species were comparable in biomass but differed in the amount of detectible genetic material produced; density and biomass were the superior abundance metric correlated with eDNA concentration for wood frogs and leopard frogs, respectively. However, increases in eDNA concentration reflected increasing tadpole biomass, therefore biomass is likely a better metric of abundance than density. Overall my findings support that eDNA concentration can be used as an index of species abundance, but that species-specific calibration may be needed before eDNA concentration can be effectively translated to an abundance metric. Future research should refine our understanding of how biotic and abiotic factors influence eDNA production, degradation, and recovery across species, before the method can receive widespread use as a monitoring tool in natural settings. Author Keywords: abundance estimates, environmental DNA, mesocosm, Rana pipiens, Rana sylvatica
Sexting and Satisfaction
Sexting was explored in relation to cohabitation status, general and sexual communication, as well as the anxious and avoidant dimensions of attachment. The present study was focused the distinction between lifetime and recent sexting, in an attempt to more accurately assess the relationships between the examined factors and sexting behaviours. Individuals in long-distance relationships were more likely to report recently sexting and engaged more frequently than those in cohabitating relationships, but did not differ in their levels of sexual satisfaction. Recent sexters reported higher levels of sexual communication compared to lifetime sexters, and sexual communication was positively, though weakly, correlated with sexting frequency. The present study was unable to support a predictive relationship between recent sexting and levels of attachment anxiety or avoidance. These results highlight the importance of exploring the context in which sexting occurs, as well as distinguishing between lifetime and recent sexters in future sexting research. Author Keywords: Attachment, Long Distance Relationship, Recent Sexting, Satisfaction, Sexting, Sexual Communication
Growth and Revitalization in Peterborough ON
The Places to Grow Act (2005) and the Growth Plan for the Greater Golden Horseshoe (2006) are two pieces of legislature passed by the Government of Ontario to help govern and limit urban sprawl in major cities across Ontario through to 2041. These policies are framed around the development and maintenance of large-scale cities. While there are some provisions within these policies for mid-sized cities that are part of the Greater Golden Horseshoe (GGH), there are few resources, case studies, and models for successful revitalization, and intensification in mid-sized cities. The goal of this thesis is to answer questions related to planning and development in Peterborough, Ontario and to assess its progress as it relates to Places to Grow (2005) and the Growth Plan for the Greater Golden Horseshoe (2006) guidelines. Through the use of library research, policy document analysis, interviews with key stakeholders, and GIS analysis, I identify both strategies and challenges related to development and growth in Peterborough, ON. I conclude that the policies are proving to be initially favorable in their results, however it is not without significant challenge to Planners and stakeholders in Peterborough, ON. Finally, I suggest further research take place in order to further assess the effectiveness of these policies in other mid-sized cities in Ontario, as well as to measure the success of the policies closer towards the 2041 deadline. Author Keywords: GIS, Peterborough, planning, policy, revitalization, Smart Growth

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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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