Manitoba Heritage Theses

Permanent URI for this collection

http://hdl.handle.net/1993/3098

Contains full text Manitoba-related theses dating from 1902 to the present.

The University of Manitoba Libraries gratefully acknowledges the financial support of the Manitoba Department of Heritage, Culture, Tourism and Sport in the digitization of many of these theses.

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Now showing 1 - 5 of 6486

Open Access
Exploring representation-level augmentation and RAG-based vulnerability augmentation with LLMs for vulnerability detection
(2025-01-23) Daneshvar, Seyed Shayan; Carson, Leung (Computer Science); Chowdhury, Shaiful (Computer Science); Wang, Shaowei
Using deep learning (DL) for detecting software vulnerabilities has become commonplace. However, data shortage remains a significant challenge due to the scarce nature of vulnerabilities. A few papers have attempted to address the data scarcity issue through oversampling, creating specific types of vulnerabilities, or generating code with single-statement vulnerabilities. In this thesis, we aim to find a general-purpose methodology that covers various types of vulnerabilities and multiple-statement ones while beating previous methods. Specifically, we first explore traditional mixup-inspired augmentation methods that work at the representation level and show that these methods can be useful, although they cannot beat random oversampling. One possible reason is that mixing samples heavily degrades the integrity of the code. Hence, we introduce VulScribeR, a RAG-based vulnerability augmentation pipeline that leverages LLMs and maintains code integrity, unlike mixup-based methods. We show that VulScribeR outperforms the state-of-the-art (SOTA), oversampling, and representation-level augmentation methods.
Open Access
Signal and noise: a comprehensive assessment of the relationship between medication use and Alzheimer’s Disease
(2025-02-24) Friesen, Kevin; Kuo, I fan (Pharmacy); Singer, Alex (Family Medicine); Gamble, John (University of Waterloo); Bugden, Shawn; Falk, Jamison
Despite a large body of research examining the associations between medication use and dementia, the issue remains unresolved. This thesis uses administrative healthcare data to examine two drug classes, proton pump inhibitors (PPIs) and benzodiazepines, and dementia risk using a methodological sensitivity analysis approach to better understand why the evidence remains equivocal, and whether these drugs do increase the risk of dementia. Cox regression models were used to model risk using a population level cohort. Subgroup analysis was used when needed to reduce indication bias. Finally, high dimensional propensity score matched cohorts were used to reduce unmeasured confounding. We found that while PPI users had modestly higher risk of dementia, this increased risk was due to higher rates of baseline comorbid conditions that are also risk factors for dementia. An analysis of PPI initiators also found that these conditions were predictors of treatment initiation and increased duration of use. After adjusting for the comorbid conditions, the association between PPIs and dementia was null. Similarly, benzodiazepine users had higher risk of dementia but also higher rates of dementia risk factors at baseline. Adjusting for these conditions reduced the estimated increased risk, although it remained significant. However, this class of drugs is most used in those with depression and anxiety, risk factors for dementia, resulting in potential indication bias. When this bias was reduced by examining cohorts of depressed persons, or of those with anxiety no increase in dementia risk was found. The pharmacoepidemiological research into dementia risk associated with prescription drugs is messy. Insufficiently controlling for the noise present in non-randomized and observational data can lead to detecting signals of uncertain validity. It is hoped that this systematic approach will raise the bar for future research in this area, and that future researchers would, before publishing alarming findings, assess more closely whether they have truly controlled for confounding, reduce the risk of bias, and that their study design can answer the question they are trying to ask.
Open Access
Does individuals' perception of CCTV cameras in public spaces influence their behaviour and sense of safety? The case of Winnipeg
(2025-03-08) Baffour Adumata, Graham; Patzer, Jeremy (Sociology and Criminology); Baffoe, Michael (Social Work); Asomah, Joseph
The safety issue in downtown Winnipeg has become a significant topic of debate in the media and government circles, prompting the implementation of various safety strategies, including closed-circuit television (CCTV) cameras. This research examines whether individuals' perception of CCTV in public spaces influences their behaviour and sense of public safety. Based on surveillance and governmentality theories and semi-structured in-depth interviews, the study addresses these critical questions: How do individuals perceive CCTV cameras in public spaces in Winnipeg, and do their perceptions influence/shape their behaviour and sense of safety? While some participants welcomed surveillance for its potential to enhance safety, others expressed distrust, citing concerns about privacy, data insecurity, racial profiling, and civil liberties. Mixed opinions emerged regarding the cameras' effectiveness in deterring crime and influencing behavior. While participants acknowledged that surveillance cameras can create a sense of awareness that influences them to modify their behaviour and potentially discourage anti-social acts, they also voiced significant concerns about their ability to truly prevent crime, believing that criminals can devise ways to evade detection. The study highlights that public safety extends beyond technology, emphasizing the need for real-time human intervention and community-based initiatives. Although surveillance cameras are perceived as a tool for monitoring, they are not seen as sufficient to ensure safety without complementary measures such as police patrols, better lighting, community bonding, and community initiatives such as Bear Clan and the Downtown Community Safety Partnership. The study contributes to knowledge by providing a nuanced understanding of public perceptions of CCTV surveillance and its impact on safety and behaviour.
Open Access
Lactating parents attending Winnipeg Breastfeeding Centre: a descriptive study
(2025-02-25) Khodabandehloo, Narges; Nickel, Nathan (Community Health Sciences); Raimondi, Christina (Family Medicine); Azad, Meghan
Introduction The World Health Organization recommends exclusive breastfeeding for the first six months of life and continuation of breastfeeding for at least two years. In Canada, 91.0% of parents initiate breastfeeding, yet only 38.0% continue six-month exclusive breastfeeding. The Winnipeg Breastfeeding Centre (WBC) is the only clinic in Manitoba providing physician-level lactation care. My project aimed to describe the WBC patients’ demographic characteristics, breastfeeding difficulties, diagnoses, and treatments. Methods This retrospective study describes the WBC population from March 2018 – December 2023 using the clinic’s electronic medical records, following the exclusion of follow-up appointments. The data included: intake questionnaire (n=3,230), referral data (n=6,778), and a random sample of the visit notes (n=79). To facilitate descriptive analysis, I manually extracted and coded the free text data from visit notes, which involved converting the "assessment and plan" sections into discrete variables reflecting diagnoses and interventions (i.e. education and supportive psychotherapy). Results WBC received referrals from physicians (79.7%), nurse practitioners (1.1%), and midwives (0.1%). The mean infant and maternal age were 8.7 weeks (SD ± 11.4, 95% range 1.0 - 37.4) and 34.8 years (SD ± 4.7; 95% range 25.0 - 44.0), respectively, with 57.9% primiparity and 65.7% vaginal delivery. The WBC patient population mostly resided in Winnipeg (75.0%), Southern Health (15.0%), and Interlake-Eastern (8.1%) regional health authorities. Fort Garry, River East, and Saint Boniface were the most common locations in Winnipeg (34.4 % combined). Referrals to the WBC rose 2.1-fold after March 2020 (COVID-19 pandemic onset) compared to pre-pandemic and remained elevated post-restrictions (May 2023), reflecting both clinic growth over the years and COVID-19 pandemic conditions. At the time of referral, 40.6% of the patients were taking medication, and 42.1% had one or more medical conditions, with the most common being depression or anxiety (20.1%) and thyroid disorder (8.8%). Patients reported supply issues (54.6%), nipple pain (43.8%), and tongue tie concerns (29.6%) as reasons for attending the WBC. In comparison, infant feeding mechanic challenges (35.4%), low milk supply (30.4%), and nipple issues (30.4%) were the most common WBC physician-diagnosed difficulties. The higher percentage of reported low milk supply compared to diagnosed cases indicates that many parents perceived having a low milk supply without actually having it. Education, supportive psychotherapy, and prescriptions were identified as the main WBC intervention strategies. The most common education topics included infant care discussion (77.2%), feeding guidance (74.7%), and latch education (73.4%). The most common supportive psychotherapy topic was emotional status (anxiety and adjustment reactions) (43.0%). 10.5% of the WBC dyads received a prescription, with domperidone being the most common, prescribed to 6.1% of the clinic dyads. Conclusions This study lays the foundation for future research within the WBC and highlights the need to expand specialized lactation care beyond the Winnipeg region, provide timely interventions or referrals (e.g. tongue-tie release), and integrate infant care and lactation education into existing services.
Open Access
Performance investigation of piezoelectric PVDF-TrFE polymer for it's mechanical and electrical response and use as vibration sensor
(2025-03-04) Riaz, Naeem; Bridges, Gregory (Electrical and Computer Engineering); Wu, Nan (Mechanical Engineering); Mrad, Ridha Ben (Mechanical and Industrial Engineering, University of Toronto); Shafai, Cyrus
Piezoelectric polymers, such as PVDF-TrFE, are increasingly studied for their potential to replace traditional ceramic based piezoelectric materials due to their flexibility, ease of processing, and strong adhesion properties. This study focuses on PVDF-TrFE with a 75/25 molar concentration, emphasizing the enhancement of the β-phase to improve piezoelectric output. The research explores various techniques to increase the β-phase without requiring extensive stretching or polling processes. Notably, the addition of the TrFE co-polymer to PVDF negates the need for such processes, inherently boosting piezoelectric performance. The experimental study utilized PVDF-TrFE dissolved in two different solvents: MIBK (Methyl Isobutyl Ketone) and DMSO (Dimethyl Sulfoxide). In the initial phase of the experiments, piezoelectric solutions based on MIBK and a combination of MIBK and DMSO were spin-coated onto flexible KAPTON cantilevers and annealed to form thin films. The mechanical properties were then assessed using a vibration test system. It was observed that films created with MIBK alone exhibited higher vibrational amplitudes than those formed with a mixture of MIBK and DMSO. Additionally, higher concentrations of PVDF-TrFE resulted in greater vibrational amplitudes, suggesting a direct correlation between polymer concentration and mechanical responsiveness. Notably, the films made by a 1.25% MIBK+ DMSO based polymer solution produced an equivalent sensitivity to the films made by a 3% polymer solution. The equivalency is due to the presence of DMSO (polar nature) solvent and its ability to form long chains during the baking process. In contrast, the latter solution produced thicker films than the former due to the increased quantity of polymer. The performance of laboratory based vibration sensors fabricated using PVDF-TrFE was compared with existing ceramic based devices and commercial vibration sensors. The results indicated that PVDF-TrFE sensors generated comparable, if not higher, piezoelectric voltages than their ceramic counterparts. This finding underscores the potential of polymer based sensors in practical applications, offering advantages in flexibility and adhesion without sacrificing performance. Further experiments involved fabricating a 5 x 2 mm cantilever on a PCB using a laser cut process. This cantilever responded to acoustic signals ranging from 400 Hz to 1200 Hz and produced a 0.011 V output voltage during vibration tests. Another U-shaped sensor, incorporating electroplated copper, spin-coated PVDF-TrFE, and silver sputtering, was tested as a Lorentz force actuator and sensor. The sensor exhibited responsiveness to magnetic elds and sinusoidal voltages, highlighting its multifunctional capabilities. Additionally, a vibration sensor was made on a bearing surface and subjected to motor induced vibrations, demonstrating a clear output signal, driven purely by the motor's rod vibrations.

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