Open Theses and Dissertations
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Item Open Access Identifying Somatic Variants using DNA Derived from Stereo-Electroencephalography Electrodes in Patients with Focal Epilepsy(2024-11-04) Mascarenhas, Rumika; Klein, Karl Martin; Tarailo-Graovac, Maja; Kurrasch, Deborah; Wiebe, SamuelBrain somatic variants play a crucial role in the etiology of focal epilepsy. Detecting these variants is challenging due to their presence in a subset of cells, resulting in a reduced variant allele frequency (VAF). Traditional methods rely on brain tissue obtained during resective epilepsy surgery, limiting accessibility and applicability, especially in patients with non-lesional epilepsies who are less likely to undergo surgery. In response to these limitations, a novel approach utilizes DNA extracted from depth electrodes employed in stereo-electroencephalography (SEEG) procedures. This method offers several advantages over resected brain tissue, such as the inclusivity of patients not undergoing surgery and access to multiple brain regions through implanted depth electrodes. Recent studies demonstrated the feasibility of detecting somatic variants using SEEG-derived DNA, highlighting its potential in non-lesional epilepsies. However, challenges remain, including potential cell contaminations and lower cell yields, necessitating DNA amplification that introduces associated artifacts. This thesis introduces an improved SEEG harvesting protocol addressing these issues. Our optimized technique purifies neuronal nuclei, mitigating cell contaminations, and incorporates a newer amplification method to minimize artifacts. Additionally, the thesis introduces the implementation of quality control steps for sample selection and a bioinformatic workflow to reduce artifactual and false positive variants, enhancing the reliability of downstream variant identification. With these improvements, this project aims to enhance the reliability and applicability of SEEG-derived DNA in understanding the molecular basis of focal epilepsy, paving the way for diagnosis and improved treatment strategies.Item Open Access Ultrasound Mediated Mild Hyperthermia Resolves Neuroinflammation in an Animal Model(2024-11-01) Seasons, Graham; Pike, Bruce; Kuipers, Hedwich; Pichardo, Samuel; Dunn, JeffChronic neuroinflammation is an often overlooked aspect of the development of neurodegenerative and autoimmune disease, especially in older populations, and there are few treatments capable of addressing this type of inflammation. We sought to address this gap by following up on our clinical finding where focused ultrasound resolved chronic radiation-related neuroinflammation Using ultrasound-mediated mild hyperthermia to treat chronic neuroinflammation in a preclinical mouse model, we investigated the impact on the immune response, and the resolution of inflammation. Seven days after peripheral infection, we targeted the mouse midbrain with focal hyperthermia (4 mins at 39 oC and 6 mins at 42 oC). Proteomic changes were analyzed, and demonstrated that hyperthermia reduced inflammation in female mice 24 hours after treatment, alleviating blood brain barrier disruption, antigen presentation, and anti-viral signalling. In contrast, male mice did not show a change in inflammatory mediators at 24 hours, but showed an upregulation in proteins associated with the heat shock response, chromatin maintenance, and chaperone mediated autophagy. At the cellular level, microglia and astrocytes demonstrated homeostatic phenotypes seven days after hyperthermia treatment in both males and females. We also investigated the role of the immunosuppressive CD200/CD200R signalling pathway in immune resolution, and discovered that it is dysregulated in chronic neuroinflammation – exacerbating inflammation in males, while maintaining a resolving function in females. Ultrasound mediated mild hyperthermia was able to restore homeostatic CD200/CD200R signalling, alleviating the pro-inflammatory rewiring observed in males. Consequently, we demonstrate that ultrasound mediated mild hyperthermia is capable of restoring the homeostatic function of receptors, and resolving chronic neuroinflammation across pathology, through the induction of the heat shock response. We propose a new application of clinically approved magnetic resonance guided focused ultrasound systems in the treatment of chronic neuroinflammation, with the potential for rapid clinical translation.Item Open Access Urban design, climate + context: Exploring the interplay of thermal comfort and human perception in the case of Lahore, Pakistan.(2024-10-28) Mazhar, Naveed; Dall'Ara, Enrica; Sinclair, Brian Robert; Kenny, Natasha; Hachem-Vermette, CarolineWeather is arguably the most important human thermal comfort factor, both as an actual and perceived component, from a user's viewpoint. The user's received energy, real or presumed, is highly decisive in how well an outdoor space is used. The present study illuminates the human perceptual mechanisms involved in an urban open environment and human thermal comfort assessment, emphasizing hot climates. The primary objective is to identify underlying conditions influencing people's behaviour and usage of outdoor spaces. An in-depth literature review demonstrated that a physiological approach alone is inadequate in characterizing human thermal comfort conditions. Therefore, embracing a holistic approach, a novel conceptual model is proposed, aligning direct and indirect factors. The proposed model, Man vs. Machine, is a two-pronged approach focusing on qualitative and quantitative parameters. This study deciphered the effects of weather parameters (e.g., air temperature, wind, and solar radiation) and personal factors (e.g., place perception, emotions, sensations, and behaviours) on participants' emotional estimations of urban open spaces. Fused with the physical design components, the proposed model distinguishes the simultaneous and equal assessment of the two fundamental characteristics – empirical measurements and subjective human feelings. The study investigated four neighbourhoods – Mohallaz in the Walled City of Lahore, Pakistan. Users of urban open spaces are the fulcrum, and the intended Man vs. Machine conceptual framework is a robust side-by-side comparative analysis of the unique domains of urban microclimates, human psychology, and behaviour. The proposed study model handled only simple computations through the COMFA model to ensure quality results, such as charts of energy budgets and the total amount of radiation absorbed by a person ( Rabs) and a comparative analysis. At the collective level, the comparative charts based on site surveys informed the behavioural pattern(s) obtained from a 20-day field study comprising 800 respondents. At the individual level, cross-comparisons of thermal comfort and spatial perception helped derive theoretical and practical environment-behaviour relationship(s). The final results, derived from 800 studies, were categorized into two key factors: a) the site’s microclimate and b) the user’s spatial psychology. The analysis revealed that 65% of respondents (520 out of 800) sitting outdoors during summer felt satisfied with their experience. However, it is crucial to note that despite these perceptions of spatial satisfaction, 62% of the recorded time data indicated that respondents were vulnerable to danger or extreme danger of heat stress, according to the HTCI scale. The study determined that outdoor thermal discomfort is peripheral for users compared to the sense of place factor. The motivational factors with the most demonstrable impact on human spatial perception(s) and outdoor open space usage are space uniqueness, spatial affinity and individual features of traditional Mughal architecture. The study is groundbreaking, unique, and unparalleled in the realm of hot-climate cities. It represents a substantial and valuable advancement in comprehending the psychological factors that impact human thermal perception and behaviour in urban environments, with implications for urban design. The results of this research aimed to change how architects and environmental behaviour experts approach urban design and improve the built environments by using design recommendations outlined in the research.Item Open Access Multi-Frequency Microwave Interactions of Snow-Covered Arctic First-Year Sea Ice(2018-08-20) Nanda Kumar Sreeletha, Vishnu Nandan; Yackel, John J.; Else, Brent G. T.; Hall-Beyer, Mryka C.; Kim, Jeong Woo; Tonboe, Rasmus TageIn this thesis, the thermophysical, dielectric and Ku-, X- and C-band polarimetric microwave properties of relatively smooth snow covered first-year sea ice (FYI), from late-winter to pre-early melt onset thermodynamic regime are investigated. Fully-polarimetric microwave backscatter data acquired from a unique, surface-based multi-frequency (Ku-, X- and C-band) scatterometer system is used near-coincident with in situ snow thermophysical measurements, to investigate thermodynamic and electrical state of snow covered FYI. Using a first-order microwave backscatter model, a multi-frequency framework is theoretically established to determine the dominant snow thermophysical properties sensitive to the modeled microwave backscatter, at Ku-, X- and C-band frequencies. Multi-frequency microwave observations acquired from the scatterometer system are then used to inter-compare with modeled backscatter, to investigate the potential of the surface-based system to determine the thermodynamic and electrical state of snow covered FYI, at diurnal and temporal scales, from late-winter to pre-early melt onset. A unique frequency-dependent polarimetric parameter is developed to characterize frequency-dependent changes in microwave backscatter, as a function of snow thickness, polarization and incidence angle. Theoretical and observational findings indicate significant influence of snow salinity affecting microwave propagation through snow covers on FYI, for all three frequencies. These findings are utilized semi-empirically to develop a thickness-dependent snow salinity correction factor to improve FYI freeboard and thickness measurement retrievals from space-borne radar altimeters, operating at Ku-band.Item Open Access Characterizing Physical and Hydrotechnical Properties of Sediments Surrounding Soap Hole Features Near Didsbury, Alberta, Canada(2024-10-22) Cunningham, Dylan Z.; Lauer, Rachel; Karchewski, Brandon; Hayley, JocelynSoap holes are discrete occurrences of fluidized sediments that have been reduced to zero effective stress resulting in quick conditions. These features can be detrimental to farming operations through evaporitic concentration of ions in surface sediments surrounding the features or by fatally trapping livestock. Currently, the sediment properties and subsurface conditions required to generate soap holes are relatively unknown. A site investigation conducted near Didsbury, Alberta, analyzed the geologic, hydrogeologic and geotechnical conditions surrounding four active soap hole features to improve the understanding of soap hole formation. Glacially derived surface sediments and Paskapoo formation bedrock were extensively analyzed using a combination electrical resistivity tomography (ERT), cone penetration testing (CPT), and sediment coring and sampling. Laboratory analyses were completed on recovered sediment samples to determine index properties, particle-size distribution, Atterberg consistency limits, dispersive properties and chemical composition. ERT transects indicated there are three distinct sedimentary units on-site, and bedrock depth of approximately 11-mbgs, which was confirmed by drilling. Near-surface sediments are primarily comprised of non-sensitive, over-consolidated fine-grained material, with medium to high plasticity, and are highly dispersive. Discontinuous coarse-grains sediments were also noted in the sediment core, potentially providing flow-paths through the extensive fine-grained sediments. Hydrogeologic conditions were analyzed utilizing pressure transducer data, manual water level measurements, CPT correlations, and single well response tests. Artesian conditions were confirmed within a soap hole feature that was instrumented on site and are suspected to persist in the surrounding features. Pore pressures within and below the instrumented feature correlate with regional potentiometric surface maps of the Paskapoo formation, suggesting hydraulic connection to deep groundwater flow-paths. Strong upward vertical gradients (>1-m/m) within the soap hole feature exceed the critical gradient of surrounding sediments. Downward vertical gradients less than critical were found in most background sediments surrounding the features. Overall, sediments at the study site did not have properties indicative of being prone to liquefication. However, results suggest that high pore pressures, dispersive soils and vertical hydraulic gradients exceeding sediment critical gradients are some of the primary formation mechanisms of the soap hole features.Item Open Access Design of Phase Shifters for Phased Array Antenna Applications(2024-10-24) Jebeli Haji Abadi, Ali; Ghannouchi, Fadhel M.; Ghannouchi, Fadhel M.; Helaoui, Mohamed; Belostotski, Leo; Fapojuwo, AbrahamThis thesis presents a method for reducing the complexity of the I-Q phase shifter. This new method is based on the I-Q phase shifter architecture, where the input signal is divided into two orthogonal paths. By adjusting the amplitude of these two signals and then combining them, a signal with a phase difference relative to the input signal is obtained. The variable attenuators used in this method must be adjusted based on the required phase shift, and these attenuators are controlled by the system's control unit through multiple control lines. By reducing the number of control lines in this phase shifter, we effectively decrease the complexity and load on the control section. In this work, we first introduce a Voltage Variable Gamma Phase Shifter. This phase shifter requires only one control line and provides continuous phase variation. In this approach, the input divider is replaced with a circulator, and the two attenuators are replaced with a single variable resistor. The variable resistor is a PIN diode, controlled by a single control line. This phase shifter was fabricated and tested at 3.45 GHz with a bandwidth of 300 MHz. It provided approximately 95 degrees of phase change, with insertion loss less than 14 dB. The limitation of this method is the circulator, which prevents its use in Microwave Monolithic Integrated Circuits (MMIC). To address this issue, we have developed the next version of this phase shifter. The second step in this thesis involves modifying the Voltage Variable Gamma Phase Shifter to make it suitable for MMIC applications. To achieve this, we replace the input circulator with a coupler. This method has its own pros and cons. Although this version can be used in MMIC applications, we do not have control over both paths, which means we will lose the ability to vary the phase. In this configuration, since we have control over only 50 percent of the input signal, we will lose at least 50 percent of the phase variation. This phase shifter has been fabricated and tested at 3 GHz with a bandwidth of 400 MHz. The final step is the MMIC version of this phase shifter. Using a GaN substrate and 250 µm technology, we designed the MMIC phase shifter using the process design kit (PDK) from United Monolithic Semiconductor (UMS).This phase shifter provides a phase variation of 40 degrees and a bandwidth of 400 MHz at 3.5 GHz, with an insertion loss of less than 8 dB. The dimension of the final version of this phase shifter is 2 by 1.6 mm.Item Open Access Associations between Neighbourhood Built Environment and Leisure and Transportation Physical Activity among Canadian-Born Residents and Recent and Established Immigrants in Canada(2024-10-22) Masihay Akbar, Hasti; McCormack, Gavin Robert; Turin, Tanvir Chowdhury; Olstad, Dana LeeDespite well-established health benefits, nearly half of adults in Canada do not engage in enough physical activity for optimal health benefits. In Canada there are differences in physical activity levels among immigrants and non-immigrants. The built environment has the potential to reduce or widen inequalities if its effects on physical activity differ among population subgroups. While evidence has highlighted potential differences in how the built environment is associated with physical activity across various population subgroups, some equity-seeking groups, such as immigrants, have received little research attention. Globally, most studies examining this association among immigrants have been conducted in the U.S., with inconsistent findings. The study presented in this thesis addresses these knowledge gaps, guided by two relevant theoretical perspectives, including the socioecological model and acculturation theory. The aim of this research was to generate novel evidence regarding the associations between the neighbourhood built environment, specifically objectively-measured walkability, and physical activity according to residency status (Canadian-born, recent immigrants, and established immigrants). Our objectives were 1) to estimate and compare TPA and LPA participation and duration between Canadian-born, recent and established immigrant adults and determine whether neighbourhood walkability accounts for any observed residency group differences, and 2) to estimate and compare the direction and magnitude of associations between neighbourhood walkability and TPA and LPA participation and duration between these groups. The study included cross-sectional analysis of nationally representative data from Canadian Community Health survey (CCHS 2017-2018) linked with 2016 Can-ALE data. We found that recent and established immigrants were more likely than Canadian-born to participate in TPA, but these differences attenuated after controlling for walkability. Moreover, recent and established immigrants were less likely to participate in LPA and undertook fewer LPA minutes, compared to Canadian-born individuals. However, the differences in LPA minutes attenuated after controlling for walkability. Walkability was positively associated with TPA participation and duration in all residency status groups, but the magnitude of these associations differed between these groups. Findings from this thesis suggest that improving neighbourhood walkability could have broad public health benefits, but tailored strategies are essential to address the needs of immigrant populations.Item Open Access Characterisation of universal qudit gates(2024-10-21) Amaro Alcala, David; Sanders, Barry Cyril; de Guise, Hubert; Emerson, Joseph; Simon, Christoph; Scandolo, Carlo Maria; Feder, DavidTo harness the potential of quantum computing, increasing the number of quantum units, a process known as scaling, is critical. Whereas qubits have traditionally been used as the units for quantum computing, the development of multi-level systems (qudits), which offer larger Hilbert spaces and advantages over qubits in cryptography and circuit complexity reduction, requires new methods to characterise the quality of quantum gates and ensure safe scaling. Randomised benchmarking offers a simple and inexpensive method for this characterisation. This thesis reports advances in the characterisation of universal single- and multi-qudit gates. I introduce the characterisation of universal qutrit gates through the definition of an optimal scheme that requires similar experimental resources as the standard method for non- universal gates. The feasibility of my qutrit scheme is tested numerically using parameters from experimental qutrit implementations. I then generalise my qutrit results and devise a general scheme for a qudit system with arbitrary d. Because using the same construction for qudits with d > 3 as in the qutrit case leads to more than two parameters, a different strategy was necessary. I note that my qudit characterisation obtains an estimate of the average error per gate; thus, this characterisation is collective. A more realistic characterisation requires estimating the average gate fidelity of a single non-Clifford gate. In the last part, I generalise my qudit method to individually, in contrast to the previous collective result, characterise non-Clifford gates. My schemes are relevant to at least two communities: experimental groups with a qudit platform, as my work effectively characterises a complete gate set, and randomised bench- marking theorists, who may be interested both in the gate set I introduce and in the schemes I developed.Item Open Access Nurses Experiences, Long-Term Care, and Covid-19(2024-10-17) Gruszecki, Holly; McGhan, Gwen; Venturato, Lorraine; McAffrey, Graham; Toohey, Ann; McGhan, Gwen; Venturato, LorraineThis master’s thesis explores the experiences of registered and licensed practical nurses working in long-term care both during, and in the immediate aftermath of the Covid-19 pandemic in Alberta, Canada. Using Van Manen’s Phenomenology as a guiding research methodology, semi structured interviews were conducted with registered and licensed practical nurses working in long-term care to explore the experiences of the participants. There were four common themes identified from the data: (1) fear and uncertainty, (2) workload, (3) burnout, and (4) resilience and adaptability. These themes have been explored in comparison to the literature with the intention to provide recommendations for future pandemics and the retention of a robust, healthy, and experienced workforce. As the healthcare landscape in Alberta approaches another period of change and flux with the introduction of a system wide restructure, these findings may relate to on-going change within the sector and the turbulence that nurses experience following change. In the wake of the pandemic, the experiences of nurses who battled through it can inform policy makers to implement policies that leverage the strengths of the long-term care nursing workforce.Item Open Access Improving Sidewalk Maintenance through Smartphone Citizen Reporting of Pothole Damage(2024-10-18) Sornsakul, Chavisa; Lichti, Derek; O'Keefe, Kyle; Radovanovic, Robert; Detchev, IvanPedestrian walkways potholes pose significant risks to pedestrian safety, causing accidents and disruptions. This thesis explores using Structure-from-Motion (SfM) 3D reconstruction with smartphone GNSS measurements to improve citizen pothole reporting, aiming to enhance local engagement, infrastructure management, and public safety. The methodology uses SfM camera poses recovered from citizen pothole image reports and relative positioning from smartphone GNSS measurements to resolve the scale ambiguity of SfM pothole models. The relationship between images and a reconstructed point cloud from the SfM technique estimates pothole quantity, perimeter, and maximum depth. Key contributions include developing an integrated system for accurate pothole dimension measurement, with a scale error of approximately 12% from reference measurements, and establishing data acquisition guidelines for assessing the reliability of citizen-reported data. This method results in pedestrian walkway pothole perimeters differing by approximately 35 cm and depths by less than 1 cm. A guide for citizens capturing pothole images is proposed.Item Open Access Forest Cover Influences the Predictions Made by Species Distribution Models: A Case Study of American hazelnut (Corylus americana)(2024-10-11) Cramb, Nicholas; Vamosi, Jana; Dawson, Andria; Galpern, Paul; Yeaman, SamuelSpecies distribution models can be used to predict climate impacts on biodiversity and guide conservation efforts. However, they may not fully represent biological reality when they entirely rely on climate variables alone and neglect biological interactions. My research objective is to test if including forest cover as a quantitative proxy for shrub-canopy interactions improves the predictive ability of species distribution models. My work focuses on American hazelnut (Corylus americana) as a case-study to test this framework. American hazelnut is a good candidate species because it is widely distributed throughout the eastern temperate and northern forests of North America and is likely to interact with the full gradient of 0 to 100% forest cover. The species remains understudied regarding the determinants of its distribution, despite an excellent fossil pollen record. This project used the hazelnut fossil pollen record to model the influence of canopy cover on distribution through time and to test whether hazelnut niche has been stable over time. For distribution models of American hazelnut, I found no difference in model performance when land cover variables are included at a continental extent. However, at a regional extent I found significant increases in model performance when forest cover was included. These findings suggest that land cover can more precisely define where species habitat exists at a local level compared to climate variables alone. Distribution models developed using fossil pollen occurrences and climate simulations indicate that hazelnut has maintained a consistent niche space over the past 11,000 years before present. However, the limitations of fossil pollen data created less certainty in these results. Future work involves testing this framework on additional species to determine if these patterns are consistent across woody taxa, as well as testing if land cover datasets that are more categorically resolved and include human impacts are able to improve distribution models.Item Open Access What are the impacts of COVID-19 restrictions on nurses’ emotional labour in the hemodialysis workplace?(2024-10-16) Saleem, Moomna; McGhan, Gwen Evelyn; Jackson, Jennifer; Venturato, LorraineIn an effort to contain the coronavirus (COVID-19), nurses were required to socially distance from their patients and use personal protective equipment (PPE). The proximity of nurses and their patients meant that COVID-19 restrictions have impacted the nurse-patient interactions and how nurses perform emotional labour. Most of the research conducted on emotional labour in the nursing profession has been performed in acute care settings; however, there are no known studies that explore the emotional labour of nurses in hemodialysis, where nurses and patients have repeated interactions. In addition, how the COVID-19 restrictions impacted these relationships is also unknown. To examine the impacts of COVID-19 restrictions on nurses’ emotional labour in the hemodialysis workplace, the qualitative methodology of interpretive description was used. Hemodialysis nurses who provided direct patient care in Canada were invited to participate in an online interview. Zoom interviews were conducted (n=6) to explore and understand nurses’ experiences of emotional labour with COVID-19 restrictions in hemodialysis. The results of the interviews suggest that relationships in hemodialysis are casual and friendly. Due to the COVID-19 restrictions, continuous face masking and social distancing presented as physical barriers to developing and maintaining a therapeutic relationship. Nurses attempted various techniques to overcome the challenges that physical barriers created by trial-and-error. Practice experience and exposure to physical barriers, such as face masks and social distance, contributed to the development of confidence. Extensive work experience allowed nurses to feel more confident in their practice and ability to deal with challenges, such as the COVID-19 pandemic. Based on the study’s results, policy makers and healthcare system leaders can help ease the challenges faced by hemodialysis nurses. They can provide additional education and training for nurses on techniques and strategies to help overcome the challenges posed by physical barriers mandated during a public health emergency. This will allow nurses to learn from each other’s practice experience to overcome challenges in building therapeutic relationships.Item Open Access Bloom Swizzlers for Efficient Keyword-based Private Information Retrieval(2024-10-15) Pandya, Anisha Manohar; Henry, Ryan; Reardon, Joel; Tan, BenjaminPrivate Information Retrieval (PIR) is a cryptographic primitive that allows clients to fetch information from remote databases without revealing anything about which information they are fetching to the database operators. While PIR can solve numerous privacy problems arising in our increasingly electronic society, it is a decidedly heavyweight tool whose prohibitively high latency and low throughput, coupled with its lack of expressiveness, makes it challenging to apply in real-world applications. Consequently, despite significant attention from the research community, in-the-wild deployments of PIR to date have been few and far between. This dissertation takes an important step toward making PIR more agile by introducing a novel data structure called the Bloom Swizzler. In the three decades since Chor, Goldreich, Kushilevitz, and Sudan's seminal paper on PIR (FOCS 1995), dozens of PIR constructions, proven secure under nearly as many cryptographic assumptions, have appeared in the literature. Despite the sheer number of constructions, almost all known PIR designs share a common trait: clients query for items by specifying those items' physical offsets within the database. Such a tight coupling between query construction and the underlying database's physical layout makes such PIR cumbersome for privacy practitioners and developers to use safely and correctly. Bloom Swizzlers address this by acting upon (i.e., "swizzling") clients' queries before passing them to some underlying PIR protocol, endowing almost any of the most performant PIR schemes from the literature with an efficient and intuitive key-value store interface. To accomplish this, Bloom Swizzlers synthesize ideas from two seemingly disparate constructs: Bloom Filters and Swizzlers. A Bloom Filter is a compact, probabilistic data structure that permits constant-time probable-set-membership inquiries; meanwhile, Swizzlers are a class of unary operators (represented as special 0/1-matrices) that transform vectors by rearranging, duplicating, and discarding their components. By acting as a layer of indirection between the querier and the database, Bloom Swizzlers enables a large class of PIR schemes to perform expressive, single-round keyword-based look-ups - or even query for prepared statements consisting of k-way conjunctions for relational data with multi-column keys. Moreover, with some additional effort, Bloom Swizzlers enable disjunctive queries for the value associated with any from a list of keys. Wherever a query yields more than one match, the Bloom Swizzler dictates what result gets returned; for example, one Bloom Swizzler might select a canonical representative to return (using some arbitrary, server-dictated convention) while another might return the sum or count of the matching records. We also present a proof-of-concept implementation of Bloom Swizzlers in Python and report findings from experiments designed to study the performance implications of using Bloom Swizzlers atop state-of-the-art single-server and multi-server PIR schemes.Item Open Access Outcomes of Endoscopic Retrograde Cholangiopancreatography in Patients with Underlying Mental Health Disorders(2024-10-15) Tepox Padron, Alejandra; Forbes, Nauzer; El-Gabalawy, Renée; Hilsden, Robert JayDepression and anxiety are significant contributors to the global health burden. In Canada, the lifetime prevalences of depression and anxiety among adults are around 11% and 9%, respectively. These mental health disorders (MHDs) increase post-operative adverse events (AEs), worsen outcomes, and negatively impact healthcare correlates. In gastrointestinal endoscopy settings, pre-procedural anxiety reduces patient satisfaction and increases pain sensitivity and requirements for sedatives. Endoscopic retrograde cholangiopancreatography (ERCP) is the gold standard for managing certain pancreaticobiliary conditions. However, it is technically challenging and has the highest rates of AEs and unplanned hospital encounters (UHEs) among endoscopic procedures. There is a knowledge gap regarding the impact of MHDs on ERCP-related outcomes and patient-reported tolerability with conscious sedation. This thesis presents results from two studies seeking to examine the associations between pre-existing MHDs in adult patients undergoing ERCP and: 1) UHEs within 30 days of the procedure, including unplanned emergency department visits and/or admissions for somatic symptoms only without a clear explanatory diagnosis or AE (Study 1), 2) AEs within 30 days of the procedure (Study 1), and 3) patient-reported peri- and post-procedural tolerability (Study 2). Secondary analyses of multi-centre data were conducted using logistic regression while accounting for pertinent covariates. Study 1 found no significant associations between pre-existing MHDs and UHEs or AEs in 6,648 patients undergoing ERCP within 30 days, including visits or admissions for somatic symptoms alone. Conversely, Study 2 demonstrated a significant association between MHDs and poorer patient-reported tolerability of ERCP under conscious sedation. Among 3,714 patients, significantly more participants with MHDs reported increased intra-procedural awareness and discomfort, along with greater post-procedural abdominal pain, nausea, and distension. Using these data, clinicians performing ERCP can provide accurate information regarding MHDs and ERCP-related outcomes. Additionally, increased awareness of the reduced tolerability and worse patient-reported experience measures of ERCP under conscious sedation in patients with depression and/or anxiety can help endoscopists decrease potential patient morbidity and enhance satisfaction. Further study is needed to determine potential associations between more granular MHD-related exposures and post-ERCP outcomes.Item Open Access Direct Measurement of Frequency Dependent Phase Velocity and Seismic Attenuation from the Snowflake Dataset(2024-10-16) Chineke, Chioma Agatha; Innanen, Kristopher; Trad, Daniel; Karchewski, BrandonCarbon Capture and Storage (CCS) stands out as an effective technique for mitigating the CO2 footprint in the atmosphere. Ensuring the containment of sequestrated CO2 within geological storage is crucial, necessitating continuous monitoring. The research presented here leverages data from the Newell County facility, a shallow CO2 injection project actively promoting advancements in measurement, monitoring, and verification technologies related to CCS. The seismic method proves valuable for estimating frequency-dependent phase velocities of seismic waves. The concept of dispersion reveals that seismic waves of varying frequencies travel with distinct velocities, primarily due to non-uniform elastic properties in the subsurface, leading to frequency-dependent attenuation. As a preliminary step in estimating frequency-dependent seismic attenuation, this study aims to estimate the frequency-dependent phase velocities of the seismic waves as they propagate through the earth. The chosen method involves the analysis of uncorrelated vibroseis data, with a specific emphasis on the frequency dependence of seismic velocities. The estimated phase velocities were further utilized in predicting Q using the Kolsky dispersion model. The lateral and VSP azimuth changes in the phase velocity and seismic attenuation reflect the spatial heterogeneity in the near surface.Item Open Access Effects of Candidate Genes and Polygenic Risk on the Development of Depression in Youth Experiencing Peer Victimization(2024-10-16) Kim, Min Jae; Arnold, Paul D.; Bousman, Chad A.; Long, QuanBackground: Peer victimization is a common form of childhood adversity, where children who have experienced victimization have an increased susceptibility to various psychiatric disorders including depression. However, environmental influences have varying degrees of effect between individuals, and therefore our study focused on how genetic predisposition in conjunction with environmental factors interacts to confer risk for depression. Gene by environment (G x E) interaction studies with a focus on candidate genes and polygenic risk scores (PRS-depression) have been conducted in the past for depression, but with inconsistent findings. Testing both candidate genes and PRS, and their interaction with environmental factors, may be a promising approach for understanding the complex aetiology of depression. Methods: Longitudinal data from the McMaster Teen Study have been obtained, where students initially assessed from age 10 (Grade 5) were followed to age 26 (n=875). A computer-based self-reported questionnaire was used to obtain participants’ peer victimization experience and depressive symptoms from age 10 to 26, along with their genotype data. Dopamine transporter gene (DAT1/SLC6A3), monoamine oxidase A gene (MAOA), and the serotonin transporter gene (SLC6A4) were selected for candidate gene analysis. Depression-PRS was calculated using the genome-wide metaanalysis of depression by Howard et al. (2019). Results: Peer victimization was significantly associated with depressive symptoms in adolescence (p < 0.05). Candidate gene polymorphisms and depression-PRS were not significantly associated with depressive symptoms (p > 0.05). Furthermore, there were no significant candidate gene by peer victimization and PRS-depression by peer victimization interactions associated with depressive symptoms. Conclusion: Through our study, findings suggest that exposure to peer victimization experience was independently associated with an increased risk of depressive symptoms in adolescence. Both candidate genetic variants and polygenic risk scores did not have a significant main effect on depression risk. Lastly, neither candidate gene risk nor polygenic risk of study participants were significantly associated with depression following peer victimization experiences. Future studies will greatly enhance our knowledge on how genetic risk plays a potential role in explaining individual differences in the development of depression following adverse environmental exposures, including peer victimization. Keywords: Peer victimization, depression, candidate gene, polygenic risk score, gene by environment interaction, adolescenceItem Open Access Medi, Social Human-Robot Interaction in Pediatric Health(2024-09-19) Aghel Manesh, Setareh; Sharlin, Ehud; Oehlberg, Lora; Cheatham, Michelle; Elhajj, Reda S.This research explores how we can help a person – particularly a child – in a real-world stressful situation, such as a medical procedure, cope with pain and anxiety by using an interactive, empathetic robot as a social companion. To demonstrate this, we designed and implemented behaviours for a humanoid robot called Medi through iterative prototyping, testing, and refining. We then tested Medi’s behaviours in situ during a blood draw procedure at Alberta Children’s Hospital: our goal (and thesis) was to see if Medi could help children overcome the stress and pain associated with the blood test and consequently improve their overall experience. Using a Wizard of Oz methodology, we had Medi engage the child in an affectionate conversation using physical and verbal interactions. Between the iterative design process and the testing at the hospital, we ran just under a hundred study sessions with 97 participants. We gathered and analyzed quantitative and qualitative data by collecting questionnaires and videotaping the sessions, where our results generally show that an empathetic interactive social robot such as Medi does indeed help children cope with pain and anxiety and improve their experience.Item Open Access The Role of the Elementary School Principal: Navigating the Tension Between Instructional and Social Leadership(2024-09-24) Bauer, Kevin; Friesen, Sharon; Burns, Amy; McGregor, Stephen; Winchester, Ian; Cherkowski, SabreFrom a North American perspective, education as a social system emphasizes the moral and ethical importance of supporting all students’ academic growth and success, as well as ensuring that their basic personal and social needs are met. The role of the school principal has changed significantly over the past 30 years, from primarily fulfilling an administrative function to a multifaceted role involving leading the overall improvement of student achievement, engagement, and well-being, along with ensuring the physiological, social, and emotional needs of students are met. This qualitative exploratory case study explored how five elementary school principals in one large urban school district perceived the tension between the instructional leadership and social leadership expectations of their role as they focused on meeting students' academic and non-academic needs. The research question: How do elementary school principals understand and navigate the tension between instructional leadership and social leadership that is inherent in the principal role? The research is targeted at the tensions that exist to maintain these realms of leadership, not as competitors, but as working mechanisms to support student success. Data were gathered utilizing the following methods: one-on-one semi-structured interviews, reflective principal e-journals, field notes, and site-based artifacts such as school documents and school websites. Data were analyzed using thematic and document analysis. The analysis identified six thematic sections. Time, need, supporting personnel, accountability/responsibility, external supports, and navigating complexities were the themes identified within the principals’ leadership. Eighteen findings were identified. These 18 findings draw attention to the tensions that exist for principals as they address aspects of social and instructional leadership and the ways principals work to effectively and efficiently navigate these tensions to support the students, teachers, staff, and the broader community. One conclusion that can be drawn from this study is that principals draw upon adaptative forms of leadership as they navigate the tensions to meet the needs of students in an equitable and encompassing manner. This study highlights the ways in which principals navigate social and instructional leadership to create inclusive and equitable learning environments for all members of the school community.Item Open Access Federated Learning Model Aggregation in Heterogeneous Aerial and Space Networks(2024-10-09) Dong, Fan; Drew, Steve; Leung, Henry; Drew, Steve; Leung, Henry; Ye, Qiang; Wang, MeaFederated learning offers a promising solution for overcoming the challenges of networking and data privacy in aerial and space networks by harnessing large-scale private edge data and computing resources from drones, balloons, and satellites. Although existing research has extensively explored optimizing the learning process, improving computing efficiency, and reducing communication overhead, statistical heterogeneity remains a substantial challenge for federated learning optimization. While state-of-the-art algorithms have made progress, they often overlook diversity heterogeneity and fail to significantly improve performance in high-degree label heterogeneity conditions. In this thesis, statistical heterogeneity is further dissected into two categories: diversity heterogeneity and label heterogeneity, allowing for a more nuanced analysis. It also emphasizes the importance of addressing both diversity heterogeneity and high-degree label heterogeneity in aerial and space network applications. A theoretical analysis is provided to guide optimization in these two challenging scenarios. To tackle diversity heterogeneity, the WeiAvgCS algorithm is introduced to accelerate federated learning convergence. This algorithm employs weighted aggregation and client selection based on an estimated diversity measure, termed projection, enabling WeiAvgCS to outperform other benchmarks without compromising privacy. For high-degree label heterogeneity, the FedBalance algorithm is proposed, utilizing the label distribution information of each client. A novel metric, termed relative scarcity, is introduced to determine the aggregation weights assigned to clients. During the training process, fully homomorphic encryption is employed to protect clients’ label distributions. Additionally, two communication protocols are designed to facilitate training across different scenarios. Extensive experiments were conducted, demonstrating the effectiveness of WeiAvgCS and FedBalance in addressing the research gaps in diversity heterogeneity and high-degree label heterogeneity.Item Open Access The Metabolism of Uropathogenic Bacteria in in Vitro Human Urine Cultures(2024-10-07) Chan, Carly C. Y.; Lewis, Ian A.; Turner, Ray J.; Harrison, Joe; Chaconas, George; Montenegro-Burke, RafaelUrinary tract infections (UTIs) are common infections primarily caused by bacterial colonization of the host’s bladder and/or kidney. Research into the molecular underpinnings behind UTIs primarily focused on the various macromolecular virulence factors that enable uropathogens to invade and colonize the host’s urinary tract. As such, there is an extensive body of literature characterizing these UTI-associated virulence factors. However, one important aspect that remains relatively unexplored is pathogen metabolism. Pathogens must be able to metabolize the nutrients available in its microenvironment to survive and grow within their host. Human urine is a chemically complex medium with a diverse range of amino acids and nucleic acids, but generally lacks carbohydrates, the preferred carbon source for most microbes and thus, urine is often considered a nutrient-poor substance. Recent technological advancement in metabolomic tools can allow researchers to discover new insights into uropathogen metabolism and further our understanding of how uropathogens overcome nutritional adversity and survive in human urine. To address this gap, I used liquid chromatography-mass spectrometry (LC-MS) to analyze in vitro human urine cultures of uropathogenic bacteria. My initial metabolomics survey of eight common uropathogenic species found that these species can be divided into four distinct metabolic clades: serine consumers, glutamine consumers, amino acid abstainers, and amino acid minimalists. There were also several other metabolic phenotypes exclusive to a single or a few species. Metabolites found to be secreted by uropathogens could be candidate UTI biomarkers. Previous work discovered that agmatine was a robust UTI biomarker for several bacterial species in the Enterobacterales order including Escherichia coli. Investigation into bacterial agmatine production revealed that E. coli utilizes several different decarboxylase-based acid resistance systems in urine, induced at different pH ranges. Meanwhile, a few non-Enterobacterales species, like Staphylococcus spp., were found to secrete N6-methyladenine, which was also identified as a UTI biomarker. Advances to metabolomics methods can greatly enhance the efficiency of these metabolomics analyses, and so we developed a new LC-MS strategy for monitoring microbial metabolic activity in real-time. By investigating uropathogen metabolism with current metabolomics tools, we can better understand how these pathogens may persist and thrive during UTIs.