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Recent Submissions

Access status: Open Access ,
The Inflammatory Response during Pediatric Cardiac Surgery with Cardiopulmonary Bypass and Continuous Ultrafiltration
(2026-04-09) Bierer, Joel David; Yes; Doctor of Philosophy; Medical Research Graduate Program; Received; Osami Honjo; Yes; Roger Stanzel; Pantelis Andreou; David Horne; Jean Marshall
Congenital heart disease (CHD) is the most common birth defect, and surgical correction is often the gold standard treatment. Cardiopulmonary bypass (CPB) is essential to effective cardiac operations, but it triggers a complex systemic inflammatory response, contributing to post-operative morbidity and prolonged recovery, and effective solutions to this problem have been elusive for decades. This thesis, comprising results from two prospective translational studies (Pilot and ULTRA), investigates the immunologic mechanisms underlying CPB-associated inflammation during pediatric cardiac surgery and evaluates the efficacy of continuous ultrafiltration as an immunomodulatory therapy. The Pilot study (n=40) described distinct inflammatory profiles induced by sternotomy and CPB, with sternotomy associated with systemic cytokine and chemokine activity, while CPB primarily featured complement system activation and select cytokines. Furthermore, it appeared that the complement system, and particularly the complement anaphylatoxins C3a and C5a, rather than traditional pro-inflammatory cytokines and chemokines, was most closely associated with morbid and prolonged post-operative recoveries. Sanguineous CPB prime, used as standard of care for neonates and infants, was found to contain supraphysiologic concentrations of complement factors, primarily derived from fresh-frozen plasma. Exposure to sanguineous prime accelerated the complement reaction upon CPB initiation, which was sustained throughout the CPB exposure. Continuous ultrafiltration, while shown to extract a range of inflammatory mediators, demonstrated only modest immunomodulatory effects, with no significant clinical benefit. The ULTRA trial (n=104) compared high-exchange continuous ultrafiltration to a low-exchange protocol in a double-blinded and randomized fashion. There was no difference in post-operative ventilation-vasoactive-renal scores, ventilation time, intensive care unit requirements, and the inflammatory profiles of patients in both groups were largely similar. Systemic inflammation during children’s heart surgery remains an unresolved challenge, despite modern-day perfusion technology and techniques, with significant impacts on the patient, their family and the health care system. High-exchange continuous ultrafiltration appears to have only a modest immunomodulatory and clinical impact, while new alternatives to sanguineous prime could yield important benefits for neonates and infants. This work establishes a scientific foundation for future research aimed at mitigating CPB-associated inflammation and enhancing recovery for children with CHD.
Access status: Open Access ,
Operability of a Residential Gas-Fired Clothes Dryer Using Hydrogen-Blended Natural Gas
(2026-04-09) MacLellan, Maggie; Not Applicable; Master of Applied Science; Department of Process Engineering and Applied Science; Not Applicable; n/a; Not Applicable; Dr. Paul Amyotte; Dr. Dominic Groulx; Dr. Michael J. Pegg
Hydrogen blending in natural gas (NG) is being implemented as a transitional strategy for residential decarbonization. Although hydrogen-blended natural gas (HBNG) has been investigated across a range of residential appliances, operability impacts on gas-fired clothes dryers (GFCD) remain insufficiently characterized. A standard size 7.4 ft3 (0.21 m3) DLGX5501V GFCD was used across three dry load weights (2, 4, and 6 kg) to assess drying performance for four fuel blends (NG, 20, 40, and 50 vol% H2-NG). Cycle duration, efficiency, costs, emissions, and safety metrics were evaluated under the US Department of Energy (DOE) and Canadian Standards Association (CSA) listed testing guidelines. Drying time monotonically increased with hydrogen content in NG, with the largest penalty relative to NG occurring at 2 kg and 50% HBNG (Δt = 4.89 minutes; 23.3% increase). All test trials remained below the 80-minute ENERGY STAR® cycle time limit. An empirically regressed sigmoidal correlation was developed and compared with an adapted numerical GFCD model. Both predictive models reproduced measured drying times accurately for the set of test conditions (empirical: R2 = 0.973, RMSE = 1.46 minutes; numerical: R2 = 0.987, RMSE = 1.50 minutes) and were validated using a 3 kg intermediate load weight, yielding drying time errors of 2.2% and 5.4% for the empirical and numerical approaches, respectively. Cycle efficiency increased from 42.8% to 44.1% with 20% HBNG operation, with slight declines below NG efficiency for increased blending up to 40 and 50% HBNG. Steady-state emissions decreased progressively with hydrogen blending up to 50% HBNG, with CO2 reductions from 0.371 to 0.236 vol%, CO from 4.14 to 3.00 ppm, and NOx from 2.46 to 1.97 ppm for 50% HBNG. Operational temperatures remained below upper safety limits and no instances of flashback occurred in this study. The optimum fuel in terms of efficiency and cost in this work was 20% HBNG, with heightened efficiency and minimal drying time extensions relative to NG operation. Overall effects of HBNG use on a GFCD supported maintained operability up to 50% hydrogen blending and informed the recommended upper blending limit of 50% HBNG for this appliance. Future research should investigate the long-term effects of HBNG use on GFCDs, different textile materials, and the scalability of this work with industrial drying technologies for HBNG operation.
Access status: Open Access ,
MORALIZED OBJECTIFICATION: MISOGYNY , REACTIVE ATTITUDES, AND THE SPECTRUM OF AGENCY RECOGNITION
(2026-04-09) Chiavegato, Julia; Not Applicable; Master of Arts; Department of Philosophy; Not Applicable; n/a; Not Applicable; Dr. Greg Scherkoske; Dr. Duncan MacIntosh; Dr. Kirstin Borgerson
This thesis critiques and amends an account of misogyny by examining the relationship between objectification and moral recognition. Recent philosophical discussions, particularly in the work of Kate Manne, argue that misogyny should be understood primarily as a system of social control rather than as a form of dehumanization or objectification. While this approach successfully challenges overly simplistic accounts of misogyny, it risks overlooking ways in which failures of moral recognition remain central to misogynistic practices. Drawing on P. F. Strawson’s theory of reactive attitudes, this thesis proposes a spectrum model of agency recognition that captures the gradations through which individuals may be partially acknowledged as moral agents while still being treated in objectifying or oppressive ways. The project first examines the conceptual limitations of strictly anti-humanist approaches to misogyny. It then develops a revised framework that situates objectification within a broader spectrum of moral recognition, allowing for forms of partial recognition that coexist with domination, control, or degradation. This framework is applied to several cases—including mass sexual violence, pornography, and testimonial injustice—to demonstrate how misogynistic practices can involve both moral recognition and its distortion. By conceptualizing misogyny through a spectrum of agency recognition rather than a binary opposition between recognition and dehumanization, the thesis provides a more nuanced account of how misogynistic attitudes operate and why they remain socially resilient.
Access status: Open Access ,
Sedimentary Signals of Freshwater Outflows Onto the Atlantic Canadian Shelf Over the Holocene: A Sortable Silt Perspective
(2026-04-08) White, Adam; No; Doctor of Philosophy; Department of Oceanography; Not Applicable; Dr. Patrick Lajeunesse; Yes; Dr. Paul Hill; Dr. Eric Oliver; Dr. Craig Brown; Dr. Stephanie Kienast
The sortable silt index (ss), defined as the average grain size of a sediment sample between 10 - 63 micrometers (μm), is a paleoceanographic proxy for estimating ocean current speeds at the time of sediment deposition. While the proxy was primarily developed for use in the deep sea, studies continue to both push ss into new environments and refine our understanding of ss interpretation. This thesis (a) contributes to this growing understanding of the strengths and limitations of ss and (b) generates new insights into the paleoceanographic conditions of the Labrador and Scotian Shelves (Northwest Atlantic) over the last 10,000 years, the Holocene. Chapter 1 provides a general review of ss and applications across the Northwest Atlantic. This includes several ways ss has been applied and interpreted to gain insight into local and global scale ocean change. To address the lack of standardized chemical sediment pretreatment methods across published studies, Chapter 2 examines the sensitivity of ss to various common pretreatment methods. My results indicate that ss is robust independent of pretreatment used. However, the results highlight the importance of replicates and consistent instrument operation. Chapter 3 applies ss to marine sediment cores from the Labrador Shelf. After demonstrating the suitability of ss, changes in Labrador Coastal Current flow over the Holocene and their potential drivers are discussed. My results suggest that changes in the strength of the Labrador Coastal Current were likely driven by the influence of warm and salty waters of Atlantic origin during an ‘establishment period’ 9,000 - 6,000 years before present (B.P.), and by cold, fresh waters from Hudson Strait during a ‘stabilization period’ from 6000 B.P. to the present. Chapter 4 expands the application of ss to the eastern Scotian Shelf. In this region, the results suggest an influence of the Labrador Current on the eastern Scotian Shelf, and also support ss as a proxy of environmental change, specifically the post glacial deepening of the Scotian Shelf, and the increase in wave and storm energy on the area. With this thesis, I highlight the robustness, limitations, and new applications for the sortable silt index.
Access status: Open Access ,
The Cost of the Catch: Intimate Partner Violence and Other Social Issues in Nova Scotia Fishing Communities
(2026-04-07) Heine, Kaylyn; Not Applicable; Master of Social Work; School of Social Work; Received; Dr. Karen Foster; Not Applicable; Dr. Nancy Ross; Dr. Catherine Bryan
Fishing is central to global food systems and coastal economies, yet fishing communities are shaped by hazardous labour, environmental precarity, and persistent inequities. While international research documents high rates of poor mental health, substance use, and gender-based violence in these settings, limited attention has been given to how the fishing industry relates to Nova Scotia’s intimate partner violence epidemic. This thesis addresses this gap in two parts. First, it reviews global literature to examine how industry structures intersect with economic conditions and relational well-being. Second, it draws on qualitative interviews with frontline service providers in rural Nova Scotia working in child protection and justice systems. Findings show that fishing families are overrepresented in these systems as a structural outcome of labour conditions rather than individual pathology. Grounded in the social dislocation theory of addiction and the social determinants of health, this thesis argues for trauma-informed, prevention-focused, and place-based responses.
Access status: Open Access ,
DECODING CHRONIC PAIN: SYMPTOM DIMENSIONS, PAIN MODULATION, AND PERIAQUEDUCTAL GRAY CONNECTIVITY
(2026-04-07) Aleali, Alireza; Not Applicable; Master of Science; Department of Medical Neuroscience; Not Applicable; Dr. Kim Good; Not Applicable; Dr. Carlos R. Hernandez Castillo; Dr. Rudolf Uher; Dr. Javeria Ali Hashmi
Chronic pain is a complex condition that may not be adequately explained by diagnosis alone, motivating a symptom-based approach to phenotyping. Such symptom-defined phenotypes, informed by cognitive and neural mechanisms, may enable more precise stratification and improve treatment outcomes. This study examined 159 patients with fibromyalgia and chronic back pain, along with 72 healthy controls, and grouped patients into high- and low-severity phenotypes based on pain intensity, disability, and affective burden. Groups were then evaluated across behavioral, cognitive, and neural markers. In an expectation-induced pain modulation task, high-burden patients showed impaired modulation when positive expectations were violated, which predicted greater catastrophizing and hypervigilance. Resting-state fMRI demonstrated altered periaqueductal gray (PAG) connectivity, with high-burden patients exhibiting more negative dorsolateral/lateral PAG–dorsomedial prefrontal coupling. Stepwise machine learning classified phenotype membership with accuracy above chance, improved by integrating neuroimaging with behavioral features. These findings suggest a severe chronic pain phenotype with distinct behavioral and neural markers, supporting mechanism-based stratification.