FGS - Electronic Theses and Practica
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This collection contains University of Manitoba electronic theses and practica.
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- ItemOpen AccessEvaluating zooplankton community responses to aquaculture wastewater using eDNA metabarcoding and morphological identification(2025-04-23) Dickenson, Leah; Loseto, Lisa (Environment and Geography); Docker, Margaret (Biological Sciences); Palace, Vince; Hanson, MarkInland aquaculture wastewater (AWW) is nutrient-rich due to the high stocking densities of cultivated organisms and intensive feeding inputs. Finding sustainable wastewater management strategies is critical as aquaculture is the fastest-growing food production system globally. Using aquaculture wastewater as a fertilizer for wild rice cultivation presents a potential solution since wild rice requires high nitrogen and phosphorus for sufficient growth. However, this raises concerns about possible impacts on aquatic ecosystems within the wild rice system or on receiving environments of the flooded paddy drainage. For instance, the high nutrient concentration of AWW can contribute to eutrophication and deterioration of water quality, and ammonia and metals within the AWW can result in significant toxicological effects. This research assessed the ecological effects of AWW on ecosystem health, using zooplankton communities as biological indicators within mesocosms planted with wild rice. Three experiments were conducted in different simulated Northern wild rice (Zizania palustris) ecosystems: established wild rice wetlands (UM-EW), natural wild rice stands (UM-WR), and commercial paddies (R&L). AWW was applied to treatment mesocosms across a gradient of loadings. Environmental DNA (eDNA) metabarcoding was used to analyze the zooplankton communities and was compared to standard morphological identifications to determine the efficacy of this emerging method. At environmentally relevant AWW loadings, the effects on zooplankton communities were minimal. However, calanoid copepods in the R&L study exhibited a significant sensitivity to AWW exposure. In high AWW loading treatments, increased eutrophication and declining water quality led to shifts in zooplankton community dynamics. Ammonia and metal toxicity were not identified as primary drivers of these changes. Using eDNA metabarcoding proved highly effective in achieving significant taxonomic depth of the zooplankton taxa present. While community composition results did vary between methods, similar trends and responses were observed. Additionally, using designed targeted primer sets rather than a universal primer provided a more comprehensive assessment of the zooplankton community. This research advances our understanding of AWW impacts on aquatic ecosystems and demonstrates the potential of eDNA metabarcoding for biodiversity monitoring. These findings will help inform future wild rice-AWW systems of acceptable nutrient loadings to minimize ecosystem impacts.
- ItemOpen AccessEstimation and evaluation of protein metabolism in a freshwater snail Planorbella duryi(2025-05-30) Wang, Chenyi; Silva, Robin da (Physiology and pathophysiology); Detwiler, Jillian T (Biological science); Treberg, JasonAnimal bioenergetics can be defined as the conversion chemical energy from food into forms that can be used in vivo for maintenance, development and growth as well as reproduction. Thus, metabolic strategies that maximize the efficiency of energy assimilation may be beneficial to animals, especially under changing environmental conditions like elevated temperatures. Protein metabolism is a major contributor to resting energetic costs in ectotherms and protein accretion is a central component of growth. Proteins are responsible as cellular catalysts, essential structural elements and are core to defense against heat damages. Hence, a thorough understanding of protein turnover can provide insights to how energy metabolism interacts with growth dynamics under temperature change. In this thesis, two developed methods are used to assess protein metabolism in adult as well as embryonic stages of the freshwater snail Planorbella duryi. Using a novel D5-phenylalanine tracer approach to protein metabolism to flood endogenous phenylalanine pools we measure protein metabolism in the adult snails and test the effect of temperature acclimation on both the kinetics of protein synthesis and degradation. A novel open-chambered respirometer was utilized for the estimation of protein metabolism cost during embryonic development. While biochemical processes are often associated with a 2-fold to 3-fold change per 10°C change in temperature, protein metabolism following acclimation suggests marked compensation for temperature effects in the adults. Embryonic snails showed a higher commitment of energy metabolism to protein synthesis, as may be expected given the rapid cellular turnover and growth during this life-stage.
- ItemOpen AccessHollow cone dark field imaging: automatic acquisition, and its contrast for magnesium(2025-05-27) Parsa, Farhang; Liang, Xihui (Mechanical Engineering); Guyot, Meghan (Mechanical Engineering); Zhu, GuozhenHollow Cone Dark Field (HCDF) imaging is a powerful technique, yet it remains under-used for contrast-orientation studies—particularly when rapid, well-timed illumination adjustments are required and, up to the present time of authoring this thesis, no dedicated simulation protocols exist. The key obstacle is software fragmentation: conical-illumination simulation, beam-tilt control, automatic acquisition, and quantitative validation reside in separate programs. Researchers must therefore stitch together ad-hoc scripts and file conversions, hampering usability, reproducibility, and high-throughput studies. This study addresses the challenge by presenting a single, automated framework that unifies the entire HCDF workflow. A common scripting layer (i) generates orientation grids and supercells, (ii) performs multi-slice simulations, (iii) drives the microscope through continuous hollow-cone tilts while capturing images autonomously, and (iv) overlays experimental and simulated patterns with full parameter logging—eliminating manual data hand-offs at every stage. Demonstrated on magnesium crystals, the system simulates several hundred HCDF images, with experimental contrast matching simulation closely enough to validate both model and instrument settings. By fusing simulation, real-time acquisition, and validation into one cohesive environment, the framework transforms HCDF from a specialist method into a practical, high-throughput technique helpful for routine orientation mapping and in-situ deformation studies in both academic and industrial contexts.
- ItemOpen AccessThe effects of self-compassion on responses to social stressors among individuals with social anxiety(2025-05-20) Brais, Nicolas; Bailis, Dan (Psychology); Li, Johnson (Psychology); Alcolado, Gillian (Clinical Health Psychology); Kocovski, Nancy (Wilfrid Laurier University); Johnson, EdwardSelf-compassion is a healthy way to interact with oneself in response to difficult situations. Interventions designed to increase self-compassion have focused on individuals writing self-compassionately about past negative events. It remains unclear if self-compassionate writing about anxiously anticipated events can help manage future-oriented distress. One population for whom this approach might prove beneficial are socially anxious people, for whom distress about the future is relevant. Study 1 explored whether describing anxiously anticipated events could elicit distress and whether self-compassionate writing was more effective than control writing in addressing such distress. Socially anxious participants were randomly assigned to write about an anticipated anxiety-provoking event (n = 236) or a neutral event (n = 50). The former group (n = 224) were then randomly assigned to write about that event again, in either a self-compassionate (n = 133) or neutral (n = 91) manner. Writing about the anxiety-provoking event proved effective at eliciting distress. Subsequent self-compassionate writing about the event increased state self-compassion, positive affect and determination to engage in the event. Study 2 evaluated whether writing about an anxiously anticipated task (i.e., the Trier Social Stress Test: TSST) in a self-compassionate manner would promote objective performance on the TSST and a subjective sense of success. Socially anxious university students (n = 85) completed the online study in three phases: 1) baseline self-report measures; 2) random assignment to self-compassionate writing (n =34), control writing (n = 26), or no writing (n = 25), then the TSST, and state self-report measures; and 3) one-month follow-up (e.g., social anxiety). Participants in the self-compassionate writing condition had higher confidence, eye contact, and state self-compassion compared to those in the control writing, but not the no writing condition. Exploratory analyses found that greater levels of fear of the upcoming task attenuated the effect of self-compassionate writing. Overall, results suggest that self-compassionate writing about a future anxiously anticipated event may be beneficial and that a fruitful direction for future research is to elucidate the utility of self-compassion for coping with anticipated difficulties.
- ItemOpen AccessAtomistic exploration of deformation mechanisms in metallic nanowires. ABC as a promising approach to overcome timescale limitations of molecular dynamics(2025-05-12) Sun, Cheng; Liang, Xihui (Mechanical Engineering); Wang, Jay (Mechanical Engineering); Deng, ChuangThis thesis provides an atomistic exploration of deformation mechanisms in single-crystal metallic nanowires subjected to bending and shear stresses. A significant aspect of the work involves evaluating the ABC method as a promising computational approach to overcome the inherent timescale limitations of Molecular Dynamics (MD) simulations. Through comparative analyses, distinct deformation mechanisms such as dislocation nucleation and propagation, twinning, detwinning, twin-boundary migration, and five-fold twin (FFT) boundary formation were systematically identified. While MD simulations were constrained by short simulation timescales, ABC successfully captured slow, time-dependent plastic deformation phenomena such as gradual twin-boundary migrations and stacking fault formations. Additionally, both methods revealed the formation of FFT boundaries, occurring rapidly in MD and gradually in ABC simulations, highlighting ABC’s capability to mimic long-term deformation behaviors. This work emphasizes the directional dependence of deformation modes and underscores ABC’s potential to significantly extend computational capabilities. Ultimately, these findings provide critical insights into nanowire deformation mechanisms, laying the groundwork for future research focused on optimizing nanomaterial reliability and performance.