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Recent Submissions

Access status: Open Access ,
How Relational Continuity, Serious Mental Illness, and Substance Use Disorders Shape Management of Diabetes and Hypertension: Analysis of Population-Based Administrative Health Data in British Columbia
(2025-11-20) Poarch, Eric; Not Applicable; Master of Science; Department of Community Health & Epidemiology; Received; NA; Not Applicable; Dr. David Rudoler; Dr. Cindy Feng; Dr. Ruth Lavergne; Dr. Mark Asbridge
People with serious mental illness (SMI) and substance use disorders (SUD) are at higher risk of chronic physical diseases like diabetes and hypertension and related acute complications, but face barriers to chronic disease management (including longitudinal monitoring in primary care, medication management, and laboratory testing). It remains poorly understood how relational continuity and treatment for comorbid SMI and/or SUD shape recommended management of diabetes or hypertension. I used linked BC administrative health data from April 1, 2020 to March 31, 2023 to compare patterns of chronic disease management among patients with diabetes or hypertension treated for comorbid SMI/SUD using descriptive statistics (frequency, means, and standardized differences). Modified-Poisson regression models were used to calculate adjusted risk ratios between relational continuity and recommended management and included interaction terms to evaluate whether associations were modified by SMI/SUD treatment. Findings reveal disparities in chronic disease management among people treated for SMI and/or SUDs.
Access status: Embargo ,
Active Material Investigations in Lithium- and Sodium-Ion Batteries
(2025-11-18) Garayt, Matthew; Yes; Doctor of Philosophy; Department of Physics & Atmospheric Science; Not Applicable; Jean-Marie Tarascon; Not Applicable; Jeff Dahn; Theodore Monchesky; Michael Metzger
This thesis focuses on both methods to evaluate and produce new lithium- and sodium-ion battery active materials, as well as studying the use of new active materials. It focuses on the development and use of single-layer pouch cells, all-dry synthesis of mid-nickel positive electrode materials for lithium-ion batteries, and the development and use of lead-containing negative electrode materials for sodium-ion batteries. The first part of the thesis develops a method to make single-layer pouch cells and shows the benefits of this form factor. First, a comparison between single-layer pouch cells, coin cells, and stacked pouch cells is made, showing that when single-layer pouch cells are made without a negative electrode overhang, they give the best possible electrochemical performance. Finally, single-layer pouch cells are used in a case study comparing LFP and NMC full cells. The second part of the thesis develops an all-dry synthesis technique to make NMC640 in a water- and waste-free process. The all-dry synthesis consists of mixing transition metals and metal oxides with a lithium source and an optional tungsten coating in an auto grinder before calcination. The best all-dry synthesized materials with 0.3 mol% tungsten coating perform as well or better than a commercial NMC640 material in electrochemical half cell evaluations. The remaining parts of the thesis introduce lead as a promising sodium-ion negative electrode material. First, in half cell testing, it is found that lead negative electrodes with high active material loadings can cycle with no capacity loss when their electrodes contain single-walled carbon nanotubes and the electrolyte solvent is monoglyme. However, due to the large volume change of lead during sodiation, the lead particles break down into smaller particles and cause overall restructuring of the electrode. This repeated volume change also causes irreversible capacity loss in full cells. An initial attempt is made to make lead-carbon composite active materials that can mitigate the effects of the volume change. Overall, this thesis provides insights into new active materials, new methods to test them, and new production processes for them to produce lower cost and longer lifetime batteries.
Access status: Open Access ,
MICROGLIAL ACTIVATION IN THE CAT DORSAL LATERAL GENICULATE NUCLEUS FOLLOWING RETINAL INACTIVATION
(2025-11-18) Rizwan, Safiya; Not Applicable; Master of Science; Department of Clinical Vision Science; Received; Donald Mitchell; Not Applicable; Nadia Dicostanzo; Kevin Duffy
Amblyopia is the leading cause of monocular vision loss in children. Success in treating amblyopia using conventional methods such as patching and atropine penalization are hindered by compliance issues, rigid treatment schedules, and a short treatment window during young childhood. Thus, alternative treatments addressing these barriers are necessary to improve visual outcomes. Retinal silencing, by administering intravitreal injections of tetrodotoxin (TTX), is a potential treatment for amblyopia in lieu of patching or penalization. Fellow eye retinal silencing has shown good results in promoting visual recovery of the deprived eye, with no permanent detriment to the silenced eye. However, the underlying mechanisms that protect the eye during silencing are not fully understood. Microglia are a subtype of glial cells involved in mediating the development of the synaptic network in the central nervous system. The current study sought to determine if microglia are involved in a homeostatic response that protects the synaptic network against lowered neural activity elicited by retinal silencing. In other words, how are synapses-serving the inactivated eye protected from perturbation? Microglial activation was investigated as a possible protective mechanism by measuring ionized calcium binding adaptor molecule 1 (Iba1) immunolabeling within the silenced- eye layers of the dorsal lateral geniculate nucleus. The results of this study revealed that retinal silencing in young animals activates microglia, and that retinal silencing in older animals did not elicit such activation. These findings raise the possibility that activation of microglia mediates a homeostatic response to protect against retinal silencing-induced synaptic modifications. The current study also showed that retinal silencing in younger animals activates microglial transiently, as activation is not sustained following TTX with a period of binocular vision. As TTX treatment stands as a possible alternative treatment for human amblyopia, it is important to understand how TTX affects the synaptic network of the visual system.
Access status: Open Access ,
MECHANISMS DRIVING KELP DETRITAL PARTICULATE ORGANIC CARBON (POC) UNCERTAINTIES AND POPULATION DYNAMICS IN THE EASTERN SHORE ISLANDS, NOVA SCOTIA
(2025-11-12) Savard-Drouin, Alexis; Not Applicable; Master of Science; Department of Oceanography; Not Applicable; Ramon Filgueira; Not Applicable; Katja Fennel; Kira Krumhansl; Anna Metaxas
Kelps are large brown algae that sustain marine life, support fisheries, and provide valuable ecosystem services. Carbon cycling is an important ecosystem service for kelp forests as they are among the most productive and widespread coastal vegetated ecosystems globally. However, current detrital carbon production estimates from kelp forests carry large uncertainties and studies rarely offer tangible solutions to improve them. We addressed this gap by quantifying population dynamics and demographic rates for the two dominant kelp species in Nova Scotia, Laminaria digitata and Saccharina latissima and estimate the detrital carbon production of both species. These estimates account for kelp size, since larger individuals produce more detritus, and for seasonal patterns, as most detrital production occurs in autumn. We found that most of the uncertainty in detrital carbon production estimates stems from variability in kelp density and population size structure. Incorporating seasonally varying erosion rates also reduces uncertainty as annual averages tend to over-simplify temporal patterns. Carbon cycling in kelp forests may be at risk as populations in Nova Scotia have undergone cycles of decline and recovery, with recent decades marked by substantial losses. While the causes of decline, warming waters, increased storm frequency, grazing by mesograzers, and invasive species, are known to affect individual kelps, their effects on population-level processes remain less understood. We constructed matrix population models to investigate the life history mechanisms driving the population dynamics of both species. We found that small individuals are critical for long-term population persistence. L. digitata depends on the year-round survival of small individuals, while S. latissima relies on autumn spore release, winter recruitment, and spring growth of small individuals. Stressors disrupting these life history events such as warming, turf algal competition, impacts from the invasive bryozoan Membranipora membranacea, and the mesograzer snail Lacuna vincta are therefore likely to drive kelp population dynamics. We also found that large individuals are essential for short-term population persistence and recovery. Both warming and M. membranacea negatively affect juvenile life histories and reduce the presence of large adults. The loss of large adults also would negatively impact detrital carbon production from kelps. These stressors are synergistic as warming promotes the population growth of M. membranacea. Together, our findings provide a mechanistic understanding for how continued ocean warming may undermine both the ecosystem functions and population resilience of kelp forests in Nova Scotia.
Access status: Embargo ,
Utilizing Metabolomics and Genomics to Enhance Parasite Resistance in Sheep
(2025-11-06) Jawad, Hamza; Not Applicable; Master of Science; Faculty of Agriculture; Received; Dr. Luiz F. Brito; No; Dr. Younes Miar; Dr. John Gilleard; Dr. Ghader Manafiazar
Gastrointestinal parasites, particularly Haemonchus contortus, significantly compromise sheep farm profitability. We integrated metabolomics and genomics data from 78 Rideau Arcott ewe lambs during controlled infection to develop diagnostic and genetic tools for parasite management. Metabolomic analysis identified candidate biomarkers—including indole acetic acid and trans-hydroxyproline—that demonstrated the potential to detect subclinical infections with progressive diagnostic accuracy. After validation, these metabolites could enable earlier diagnosis and treatment in precision livestock systems. Whole-genome sequencing revealed copy number variation patterns associated with parasite resistance and susceptibility. We identified key genes influencing immune function and disease resistance, particularly CLCA1 duplication. These findings provide practical tools for integrated parasite management: metabolite candidate biomarkers can be incorporated into field-deployable point-of-care diagnostics for on-farm detection, while genomic markers enable genomic selection for parasite resistance in breeding programs. Implementation of these diagnostic and genetic tools will help the Canadian sheep industry reduce anthelmintic dependence while improving productivity.
Access status: Embargo ,
Investigation of Gas Evolution and Safety of Materials for Lithium and Sodium-Ion Batteries
(2025-10-30) Tulloch, Meredith; Not Applicable; Master of Applied Science; Department of Process Engineering and Applied Science; Not Applicable; n/a; Not Applicable; Jeff Dahn; Alison Scott; Michael Metzger
The increased use of rechargeable batteries is one strategy in the fight against climate change, as a higher battery usage allows for the integration of more renewable energy sources. However, the development of batteries, particularly sodium-ion batteries, is still underway, with improvements to energy density and lifetime as the main research goals. Changes to the cell chemistry, the use of electrolyte additives, alloying negative electrode materials, and increasing the upper cut-off voltage to achieve higher cell capacity are all viable options to improve cell performance. This work explores electrolyte additives and Pb as a negative electrode material in sodium ion cells through on-line electrochemical mass spectrometry to investigate how these components impact the gases that are produced during battery operation. The electrolyte additives sodium difluorophosphate and 1,3,2-dioxathiolane 2,2-dioxide were studied in comparison to a control electrolyte through half cell tests and storage tests with notable differences in the gases evolved. Pb was compared to hard carbon and a blended electrode containing both materials to study the differences in carbonate and ether based electrolytes. Lastly, accelerating rate calorimetry was used to characterize the safety limits of a layered oxide positive electrode material for lithium-ion cells. Various upper cut-off voltages were used to probe the safety limitations of the material. Further investigation into the thermal response of the layered oxide positive electrode was completed using x-ray diffraction analysis. Overall, this work provides results for the gases produced from various cell chemistries in sodium-ion batteries, as well as the thermal responses seen in lithium-ion positive electrodes.