QSpace: Queen's Scholarship & Digital Collections

QSpace is an open access repository for scholarship and research produced at Queen's University. QSpace offers faculty, students, staff, and researchers a free and secure home to preserve and present their scholarship.

Recent Submissions

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    Exploring Maladaptive Eating Behaviors in Mood Disorders: From Phenotypic Characterization and Digital Monitoring to Psilocybin-Assisted Psychotherapy
    (2025-02-19) Koning, Elena; Neuroscience Studies; Brietzke, Elisa
    Mood disorders, including depressive and bipolar disorders, represent a complex and prevalent group of psychiatric conditions characterized by significant heterogeneity in symptomatic domains of, not only mood, but also eating behavior. The latter is a far less recognized aspect in clinical care, despite the well-documented and bi-directional neurobiological relationship with mood. The objective of this thesis is to stimulate advancement in mood disorder research and clinical care by expanding knowledge of the characterization, assessment, and treatment of maladaptive eating behaviors in mood disorders. First, we characterized eating behavioral phenotypes using both knowledge synthesis and survey-based exploratory analysis. Building on these findings, we investigated how maladaptive eating behaviors can be assessed, specifically by demonstrating the feasibility of AI-powered ecological momentary assessment and a multidimensional analytical approach to capture circadian desynchronized eating behaviors in bipolar disorders. From a therapeutic perspective, we reviewed the potential of psilocybin-assisted psychotherapy and designed a clinical trial to evaluate its potential as a personalized approach for both mood symptoms and maladaptive eating behaviors. Together, the work presented in this thesis contributes knowledge about maladaptive eating behaviors in mood disorders to researchers, clinicians, and the general public via knowledge mobilization. These findings provide a base for larger investigations to confirm the phenotypic characterizations, refine the digital assessment of maladaptive eating behaviors in psychiatry, and progress toward comprehensive, personalized therapeutic approaches that address the multifaceted nature of mood disorders.
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    Exploring the Association Between Cirrhosis and Outcomes Among Patients with Lung Cancer in Ontario Between 2007 and 2017: A Population-Based Study
    (2025-02-19) Ho, Adrienne Kaitlin Marie; Public Health Sciences; Flemming, Jennifer
    Background: Cirrhosis is a significant cause of morbidity and mortality, but its impact on outcomes in the treatment of lung cancer is not well described. Population-based data provide estimates where prospective data is lacking and may aid in the quantification of risk for patients undergoing radical and palliative treatment. Methods: All patients diagnosed with non-small cell lung cancer (NSCLC) in Ontario, Canada, from 2007 to 2017 were identified using the provincial database ICES, and those with cirrhosis were identified using validated coding. The association between cirrhosis and morbidity and mortality, both postoperatively and post-palliative systemic anti-cancer therapy, was evaluated using logistic regression, Kaplan-Meier curves, and competing risks analysis. Results: Among patients with stages I-III NSCLC who underwent lung resection (n=59,226 overall, n=1,780 (3%) with cirrhosis), patients with cirrhosis had a higher overall mortality rate at both 30 days (5% vs. 2%, p<0.001) and 90 days (8% vs. 3%, p<0.001). More patients with cirrhosis were admitted to the ICU, readmitted to the hospital within both 30 and 90 days, and stayed in the hospital longer. After multivariable logistic regression, cirrhosis was associated with death at 30 days (OR 2.35, 95% CI 1.39-3.99, p<0.001) and 90 days (OR 2.10, 95% CI 1.38-3.21, p<0.001); development of postoperative complications within 90 days (HR 1.44, 95% CI 1.14-1.81, p=0.002); and hospital readmission at both 30 (OR 1.90, 95% CI 1.41-2.56, p<0.001) and 90 days (OR 1.63, 95% CI 1.27-2.10, p=0.001). Using adjusted Cox regression among those with stage IV NSCLC, cirrhosis was associated with worse overall survival (HR 1.10, 95% CI 1.02-1.18, p=0.016). However, using competing risks analysis with liver-related morality as a competing event, there was no association between cirrhosis and cancer-specific mortality (sHR 1.04, 95% CI 0.95-1.13, p=0.395). Conclusions: Cirrhosis is associated with increased morbidity and mortality in patients with stages I-III NSCLC undergoing surgery. In stage IV NSCLC, patients with cirrhosis are less likely to receive systemic palliative treatment than their counterparts, and may experience more post-treatment complications, but are not at a significantly increased risk of death when the competing risk of liver death is accounted for.
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    Modelling and Nonlinear Control of Instability in Electric Skateboards
    (2025-02-19) Kulin, Thomas; Electrical and Computer Engineering; Pahlevani, Majid
    Electric skateboards have gained significant popularity in urban transportation, especially amongst younger demographics such as on university campuses. The electric drive system has greatly increased the speed achievable on the skateboard platform, driving the need for investigation into the dynamic instabilities associated with this unique mode of transportation. At high speeds, the skateboard system encounters a bifurcation, at which point the rider becomes unstable as a result of the interactions between the centrifugal effects on the rider and the tilt-steering mechanism. This instability commonly results in the rider being thrown from the board onto the pavement at very high speeds. In this thesis, a novel three-dimensional, four-degree-of-freedom skateboard-rider model is proposed to address the limitations of existing skateboard dynamic models. The proposed model combines the balancing efforts of a physiologically accurate rider with a spherical inverted pendulum model under the effects of fictitious forces resulting from the acceleration of the non-inertial reference frame due to the steering action of the skateboard. The proposed model is simulated and analyzed at varying velocities, truck stiffnesses, and board lengths to better understand the effects of various skateboard design parameters on stability. The model's skateboard-referenced frame facilitates its application to control system design. Using the dynamics derived from the proposed skateboard-rider model, several nonlinear control laws are proposed. The goal of these control strategies is to neutralize the high-speed instability using common-mode and differential motor torque as control inputs. The effectiveness of these control laws is compared using time-domain simulations and region of attraction analysis. The final optimal control law is implemented and tested on an electric skateboard apparatus at a range of velocities in order to verify control performance and model accuracy. When tested at low speeds, the control law is able to successfully stabilize the rider across a wide range of initial conditions, with experimental performance loosely aligning with the expected, simulated performance. High-speed testing was not conducted due to the safety concerns of the rider.
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    The Impact of Sex Differences on Abdominal Pain
    (2025-02-19) Bennett, Aidan; Biomedical and Molecular Sciences; Lomax, Alan; Reed, David
    Background: Irritable bowel syndrome (IBS) is a chronic abdominal pain disorder that affects women twice as often as men. While luminal mediators of both host and bacterial origin modulate abdominal pain in IBS patients, gonadal hormones also influence pain signaling. This PhD thesis aimed to identify the impact of fluctuating gonadal hormones on nociceptive signaling and compare the effects of fecal supernatants (FS) from male and female IBS patients on abdominal pain pathways. I hypothesized that the sensory neuronal excitability changes during the female reproductive cycle, with the proestrus/estrus stage increasing sensitivity to mechanical stimuli and luminal mediators, thus contributing to the female predominance of IBS. Methods: Extracellular afferent nerve recordings were performed to assess action potential frequency changes during spontaneous firing and in response to colonic distension in vitro, and visceromotor responses (VMR) measured the response to colorectal distension in vivo. Current clamp recording techniques were utilised to measure rheobase in dorsal root ganglia (DRG) neurons. Finally, tail flick latency tests evaluated somatic pain in vivo. FS from male and female IBS patients were used. The estrous cycle was monitored through vaginal swabbing. The production of gonadal hormones was stopped using ovariectomy (OVX) and orchidectomy (ORCD) models. Results: The findings demonstrated that FS from female IBS patients reporting high abdominal pain increased overall colonic nerve activity, but FS from male IBS patients with high abdominal pain had no effect on nerve activity. Colonic afferent nerves exhibited increased activity only when exposed to FS from IBS patients reporting high abdominal pain, compared to FS from IBS patients reporting moderate or low pain. When separating female mice based on the estrous cycle, proestrus/estrus mice exhibit increased neuronal excitability compared to metestrus/diestrus and male mice. OVX decreased spontaneous firing and afferent nerve response to distension in the presence of FS from female IBS patients. ORCD increased DRG neuronal excitability and decreased tail withdrawal thresholds compared to controls but only altered basal colonic nerve firing in the presence of IBS FS. Conclusion: This work suggests that the production of gonadal hormones impact abdominal pain signaling, potentially contributing to the female predominance of IBS.
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    Mathematical Modeling and Design of Experiments for a Heat-Integrated Biomass Downdraft Gasifier
    (2025-02-19) Haidar, Houda; Chemical Engineering; McAuley, Kim
    A mathematical model for a heat-integrated biomass downdraft gasifier is developed. This one-dimensional steady-state model accounts for pyrolysis, combustion, and gasification reactions as well as transport phenomena within the gasifier and the heating system. This model predicts the gas and solid temperatures, flow rates and compositions. The model is validated using two experimental runs and gives good qualitative results. However, the model gives unsatisfactory predictions for the composition of some gas species. This is because the 40 model parameters are poorly known and require estimation. Due to complexity of the model and the limited available data, only a subset of the parameters can be estimated. The parameters are ranked from the most-estimable to the least-estimable. Then, a mean-squared-error criterion is used to determine that 27 parameters should be estimated using data with pine wood as the feedstock. The updated model results in better predictions. Simulations show that increasing the gas demand by 50% results in 15.2% decrease in H2/CO ratio, 52.6% increase in tar content, and 44% increase in electrical energy output. The model is then extended to account for construction and demolition (C&D) waste as the feedstock. Several model equations are updated to account for the relatively high proportion of inerts in C&D waste. Eleven parameters are selected for tuning. The resulting model gives noticeably better predictions than when pine-wood parameters are used. This model is used to study the influence of different biomass feedstocks, feed moisture contents, energy demands, and solid removal rates on the producer gas. Simulations confirm that C&D waste is a promising feedstock for biomass gasification and electricity generation. Sequential Bayesian model-based design of experiments (MBDoE) is then used to propose operating conditions for additional pine-wood experimental runs for this gasifier. This MBDoE approach is valuable because it accounts for model structure, prior information about plausible parameter values, and previous experimental data. Three types of MBDoE are considered: A-optimal, V-optimal, and a new type of focused V-optimal design. The focused V-optimal methodology is recommended because it results in greater reductions in uncertainties in predictions for tar concentrations and outlet temperature than the other methods.

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  • Digital Collections
    This community includes digital collections produced by members of the Queen’s community, as well as digital special collections made available via W.D. Jordan Rare Books & Special Collections.
  • Exams & Syllabi
    This community provides access for staff and students at Queen’s University to degree examination papers and syllabi.
  • Graduate Theses, Dissertations and Projects
    This community includes graduate theses, dissertations and projects produced by students at Queen’s University.
  • Research Data
    This community includes research data produced by faculty and staff at Queen’s University.
  • Scholarly Contributions
    This community includes Queen’s peer-reviewed research publications, including journal articles, book chapters, conference proceedings, and more.