University of Lethbridge
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Song type preferences during the dawn chorus in male Adelaide’s warblers (Setophaga adelaidae)
No full textSongbirds sing a repertoire of song types, some of which are shared with neighbours. Songbirds prefer certain song types, but the reasons for these preferences are not well understood. I analyzed 11,800 dawn chorus songs from 14 male Adelaide's warblers (Setophaga adelaidae) to determine if males exhibit preference for specific song types and if these preferences are consistent across recording days. Each male had an average repertoire of 21.27 ± 3.62 song types. All males had song preferences, with the most preferred song type accounting for 17% of their song output. Song type preferences were consistent across days. I then omitted recordings that were not amenable to acoustic analysis, resulting in a reduced dataset (n = 9395), which I used to test whether males prefer (1) widely shared (locally prevalent) song types, (2) song types with superior transmission properties, or (3) song types with high or low vocal performance. I found strong evidence that males preferred widely shared songs, but the evidence for the second hypothesis was mixed. Males preferred song types with low frequency and low percent sound, supporting two predictions of the efficient sound transmission hypothesis. However, they did not prefer songs with high amplitude or high vocal deviation, negating the other two predictions of that hypothesis. Males preferred song types with low percent sound, as expected by the third hypothesis if they prefer songs with low performance requirement, but amplitude and vocal deviation had little effect on preference. This study supports the Social Dynamics Hypothesis, which states that social factors influence Adelaide's warblers' song type preference during the dawn chorus. Song sharing within the local communication networks influences male song preferences, although acoustic transmission properties and vocal performance may play a role as well
Sociodemographic determinants of mobility limitation among older adults in Canada and Nigeria
No full textThis thesis explores the sociodemographic determinants of mobility limitations among older adults (≥ 65 years) using a multi-method approach. The first study is a systematic review and meta-analysis that synthesized evidence from 57 studies involving 130,060 participants to identify associations between sociodemographic factors and performance-based mobility outcomes. Older age, female gender, non-Caucasian race, and lower education were significantly associated with mobility limitations, while gaps were identified in research on marital status, religion, and socioeconomic and residential factors. The second study analyzed six-year longitudinal data from 3,882 participants in the Canadian Longitudinal Study on Ageing, revealing significant predictors of mobility decline, including older age, female gender, retirement, non-Caucasian ethnicity, lower income, lower social status, and lack of homeownership. The third study analyzed three-year longitudinal data from 837 participants in the Ibadan Study of Ageing (Nigeria). A gender-disaggregated growth curve analysis showed that gait speed decline was slower in men compared to women, with significant predictors including widowhood and chronic disease burden for women and religiosity and high socioeconomic status for men. The fourth study, a qualitative description design, explored the perspectives of 36 older adults (18 each from Canada and Nigeria) on life-course sociodemographic determinants of mobility decline and identified demographic, socioeconomic, sociocultural, and socioenvironmental factors as critical influences on mobility trajectories. Canadians highlighted disparities in rural mobility outcomes, while Nigerians noted greater challenges for women and urban dwellers, reflecting cultural nuances. Collectively, these studies provide a comprehensive understanding of the sociodemographic factors shaping mobility trajectories in diverse contexts. The findings offer valuable insights for developing culturally sensitive, equitable policies and interventions to promote healthy ageing globally
How domestication and selective breeding changed the cerebellar anatomy and play partner preference in rats (Rattus norvegicus)
No full textDomestication has led to many changes in how animals look, behave, and physiology. With time, selective breeding has added to these changes, creating different breeds and strains with their own traits. The brown rat (Rattus norvegicus) is a good example of this process, as laboratory rats were shaped by generations of breeding, and now show clear differences from wild rats. Here, we examined how domestication and selective breeding differentially affect: 1) cerebellar anatomy; and 2) play partner preferences. Using stereology, we compared cerebellar volumes, layer volumes, and Purkinje cell sizes and numbers in Long Evans (LE), Sprague-Dawley (SD), and wild rats. LE rats had larger cerebella but smaller Purkinje cells, while SD rats overlapped with wild rats in most measures. We also tested play behaviour in groups formed by LEs, SDs and Fischer 344 (F344) rats. We found that LE rats preferred playing with their own strain and with SD rats. Both LE and SD rats, however, consistently avoided playing with the F344s. These findings demonstrate that domestication produces a mosaic of neurobehavioural changes rather than uniform changes. We highlight the need for strain-specific approaches in neuroscience research and propose future studies comparing F344 cerebellar anatomy and olfactory influences on partner choice
An investigation of stereotype threat as an insight into the replication crisis
No full textThis thesis explores the replication crisis, using stereotype threat as a demonstrative example. First, I conducted a quality control analysis using papers on stereotype threat’s effect on women’s math performance, to determine if methods and reporting had improved in the time period between 2001 and 2023. I did not find a significant improvement for the majority of the variables I tested, with the exception of sample size, average group size, and open data practices, which improved over the tested time period. Then, I designed and ran an experiment, testing the effect of implicit and explicit stereotype threat on women’s performance on a novel click accuracy task. Using this data, I first conducted a pervasiveness analysis, to determine the prevalence and magnitude of stereotype threat’s effect on participants’ scores. Within my sample, stereotype threat did not seem to cause a significant reduction in task performance compared to the control condition. Then, using Bayesian modelling, I conducted an exploratory analysis to test several ways that my results could be manipulated. First, I explored the results using four different outcome variables and found that the strength and confidence of my findings varied depending on this choice. Then, I tested the effect using two different pairs of experimenters, to determine if individual differences have an impact on the results. I found that individual experimenter variation can have a significant impact on the strength and direction of results, which may be misattributed to experimenter sex in some studies on stereotype threat. This thesis contributes to a body of work that aims to explore the causes of stereotype threat and suggests several methods for improving the quality of psychological research
Curating a corpus of Blackfoot narrative texts
No full textThis thesis documents the process of curating a corpus of Blackfoot narrative texts, referred to as the Blackfoot Narrative Text Corpus (BNTC) in the thesis. Blackfoot is a language spoken by four communities located in southern Alberta and in Montana of the United States, namely Apatohsipiikani, Kainai, Siksika and Aamskaapipiikani. The aim of this project is to develop a partially linguistically analyzed corpus of Blackfoot narrative texts to support the ongoing documentation and revitalization of the language. The corpus was compiled from published Blackfoot texts. Some texts are fully morphologically analyzed and glossed, while others were transliterated into the modern standard orthography from older spelling conventions but have not been further analyzed. After analysis and/or transliteration, the texts were integrated into the Korp corpus platform. The BNTC is an orthographically homogenous, searchable corpus currently containing 1,711 analyzed words and 8,681 unanalyzed words. It is an open-ended flexible corpus to which new texts and/or additional analysis can continually be added. This project contributes to the broader field of Indigenous language documentation providing a corpus of Blackfoot narrative texts with partial linguistic analysis, an accessible resource for learners, teachers and researchers of Blackfoot
Transformational leadership and positive development: assessing the cascade effect in university sport
No full textThe Full-Range Leadership Model (FRLM) stipulates that transformational leadership is effective because the behaviours of the leaders cascade down throughout the organization, creating more transformational leaders. However, this phenomenon has yet to be studied within the sport context. The purpose of this study was to examine the influence of the cascade effect on the relationship between coaches’ transformational leadership and university student-athletes’ (SAs) positive development (PD) over time. Using a longitudinal design, 30 athletes (20 female, Mage = 20.47) from various U SPORTS teams completed surveys at three points during their season assessing their coaches' transformational leadership behaviors (DTLI), the transformational qualities of their teammates, and their own PD outcomes (USES). Correlational analyses were used to test whether a) the number of transformational team leaders relates to changes in athletes PD, b) coaches’ TFL behaviours are related to changes in PD, and c) coaches’ TFL behaviours are related to changes in the number of transformational team leaders. Results indicated that higher levels of coaches’ transformational leadership were associated with reductions in negative sport-related experiences such as negative peer interactions and inappropriate adult behavior. Furthermore, teams with a greater density of transformational peer leaders reported stronger development in areas such as initiative, basic skills, and social capital. Evidence of a cascade effect—whereby transformational coaches influenced the emergence of transformational team leaders—was found primarily between the start and midpoint of the season. However, mediation analyses did not support the cascade effect as a mechanism linking coach leadership to PD outcomes. These findings offer novel insight into how transformational leadership functions within university sport and provide practical implications for leadership development among student-athletes
Export-led economic growth: application to Canada, USA, and the UK
No full textThis thesis explores the Export-Led Growth (ELG) hypothesis by analyzing the relationship between exports and economic growth in three advanced economies: Canada, the United States, and the United Kingdom. Utilizing annual time-series data from 1960 to 2016, the study employs unit root tests, Vector Autoregression (VAR) models, and Granger causality tests to determine whether exports drive GDP growth or vice versa. The model also includes labor, capital, terms of trade, and foreign output shocks to account for broader macroeconomic influences. The findings reveal bidirectional causality between exports and GDP in Canada, providing strong support for the ELG hypothesis. In contrast, no significant causal link is found in the United States, indicating that exports do not play a leading role in driving its economic growth. The United Kingdom demonstrates moderate evidence of export-led growth, with exports affecting GDP through specific lag structures. These results emphasize that the ELG hypothesis does not hold uniformly across countries, even among high-income economies. The thesis highlights the importance of considering country-specific factors and recommends that policymakers tailor trade and growth strategies based on domestic economic structures and external conditions
As we hold space, together: Cherokee pottery and our enduring presence
No full textThis dissertation considers earthwork mounds and the contemporary history of Cherokee Nation of Oklahoma pottery and its production both as land(scape) and an expression of our relationships to land and place. My work is an embodied inquiry of these the relationships between physical Indigenous land and concepts of place specificity as expressed through and imbued in pottery and ancient earthworks. Within this work I also argue that the creation of ancient pottery exemplifies the ways in which our ancestors utilized technological-ecological knowledge and transferred this knowledge to successive generations. My work is guided by my adherence to a critical Indigenous citational practice. It is my position that Indigenous art history must make ‘place’ an imperative part of our narratives and discourse about art and makers as a means of countering mainstream narratives about us
Advanced boundary-enhanced instance segmentation and spatial-temporal transformer models for automated schizophrenic investigation
No full textAccurate segmentation and detection in neuroimaging is essential for advancing clinical understanding and the diagnosis of schizophrenia. This thesis introduces Boundary-Refined Attention Network (BoRefAttnNet), a novel boundary-refined 3D U-Net variant specifically designed for precise segmentation of subcortical brain structures from structural magnetic resonance imaging (sMRI). BoRefAttnNet incorporates multi-scale boundary attention modules that explicitly highlight anatomically critical edges while suppressing background noise, significantly improving segmentation accuracy for small or complex anatomical structures. Evaluations using FastSurfer-processed sMRI data from the publicly available Centre for Biomedical Research Excellence (COBRE) dataset demonstrate that BoRefAttnNet significantly outperforms conventional 3D U-Net baselines in accurately delineating key subcortical structures, including the hippocampus, amygdala, and basal ganglia.
Building upon this enhanced segmentation capability, we further experiment with a Dynamic Spatial-Temporal Transformer Model (DySTTM) to detect schizophrenia by integrating structural and functional MRI (fMRI) modalities. The DySTTM leverages spatial attention to capture anatomical interdependencies from segmented sMRI data and temporal attention to model dynamic brain connectivity patterns from resting-state fMRI. Experimental results indicate that the integration of these multimodal imaging features using DySTTM provides superior diagnostic accuracy and interpretability compared to established models such as 3D ResNet and XGBoost classifiers.University of Lethbridge,
Alberta Innovates,
Digital Research Alliance of Canada,
Alberta Machine Intelligence Institute
Prefrontal regulation of exploratory behavior: complementary functions of medial prefrontal and orbitofrontal cortices in a competitive choice task
No full textThis thesis covers an experiment where rats underwent neurotoxic lesions to either the medial prefrontal cortex or the orbitofrontal cortex. Rats were then ran on a competitive decision-making task, where the rats exhibited exploratory behaviours. Exploratory behavious was compared between lesion groups.Adaptive decision-making requires balancing exploration of uncertain options with exploitation of known rewards. This thesis investigates how the rat medial prefrontal cortex (mPFC) and orbitofrontal cortex (OFC) contribute to this trade-off during a competitive binary choice task (BCT), where stereotyped responses are punished and stochastic responding is rewarded. Male Long-Evans rats received excitotoxic lesions to the mPFC, OFC, or sham surgery, then performed the BCT across stable and volatile conditions. Behavior was analyzed using generalized linear mixed models to assess trial-level changes in extraneous feeder sampling (EFS), a non-rewarded exploratory action.
Lesions did not impair overall task engagement. However, OFC lesions caused a persistent elevation in EFS during the first post-operative session, consistent with impaired suppression of valueless behavior. In contrast, mPFC lesions led to an accelerated within-session decline in EFS, suggesting a deficit in sustaining exploratory strategies over time. Under environmental uncertainty, when the physical configuration of the task changed mid-session, both lesion groups showed a blunted increase in EFS and failed to reduce exploration across days.
These findings reveal a dissociation in stable environments: the OFC is critical for value-based suppression of exploration, while the mPFC supports its flexible maintenance. Under uncertainty, both regions are necessary for adaptive exploration, suggesting that they converge within a broader prefrontal network recruited during volatile conditions. This work clarifies the distinct and overlapping roles of the mPFC and OFC in regulating exploration and offers insight into prefrontal contributions to flexible decision-making