Recherche uO Research Accueil

Recherche uO, le dépôt numérique de l'Université d'Ottawa, réunit le matériel de recherche et d'enseignement créé par notre communauté universitaire et nos partenaires. Le savoir de l'Université est ainsi disponible à long terme et en accès libre, ce qui lui procure de la visibilité et facilite sa diffusion.

Comment soumettre votre thèse

Comment déposer votre recherche

Communautés dans DSpace

Sélectionner une communauté pour parcourir les collections sous-jacentes.

Voici les éléments 1 - 5 sur 19

Nouveaux dépôts

Neural Posterior Estimation via Hierarchical Bayesian Distillation
(Université d'Ottawa / University of Ottawa, 2026-10-02) Negarandeh, Sina; Kantere, Verena
Solving inverse problems for spectral data is fundamentally hindered by data scarcity, ill-posedness, and the strict requirement for accurate uncertainty quantification (UQ). Addressing these challenges in the context of X-ray diffraction (XRD), an essential technique for materials discovery and structural health monitoring, we propose an amortized neural posterior estimation framework. Our approach distills a computationally expensive, physics-informed Bayesian teacher into a highly efficient conditional normalizing flow (CNF) student. By enforcing crystallographic constraints within our base generative model, we construct a representative synthetic training corpus to optimize the CNF, effectively bypassing the bottleneck of limited real-world data. We extensively validate the neural posterior's fidelity against the Bayesian teacher using posterior predictive checks and Wasserstein distances. Finally, we demonstrate the practical utility of this approach on a real-world structural damage detection task. Evaluated in a leave-one-group-out cross-validation (LOGOCV) setup, our amortized posteriors maintain the predictive classification performance and UQ calibration of the Bayesian baseline while accelerating inference by orders of magnitude.
Neither 'Direct Realist' nor 'Representationalist': Thomas Aquinas and Species Intelligibilis as Principle for Metaphysical and Intellective Acts
(Université d'Ottawa / University of Ottawa, 2026-10-01) Nicholson, Elisabeth June; Côté, Antoine
Many prevailing philosophical iinterpretations of Aquinas's account of human cognition follow what this thesis calls the "Standard Model," wherein species intelligibilis is abstracted or derived through agent intellect, received or "deposited" in possible intellect, retained there, and subsequently instrumentalized in concept formation, judgment, reasoning, and further intellectual operations. Despite significant differences between "Direct Realist" and "Representationalist" interpreters, both frequently retain this explanatory architecture. This MA project challenges that Standard Model by arguing that it reflects what Therese Scarpelli Cory calls a "fundamental misconstrual" of the role of species intelligibilis. Building on Cory's "Formal Constituent View," the thesis restores species intelligibilis to the metaphysical order of form and formal principle: that by which possible intellect is actualized and from which intellectual operations proceed, rather than a produced "third thing" subsequently put to use. Species intelligibilis remains genuinely similitudo, or likeness, but likeness belongs to a formal, metaphysical order rather than functioning as an additional cognitive instrument. The thesis then extends this metaphysical approach by highlighting recent works by Gloria Frost, Martin Kostelecky, and Bernard Lonergan and examining Aquinas's account through metaphysical terms such as act and potency, reception and activity, development, operation, object, and end. Although these accounts differ over the ordering and termini of intellective operations, taken together they support an alternative in which species intelligibilis remains the formal principle of an internally differentiated act whose operations are specified by their respective objects and ends. The result challenges the production-deposit-retention model itself and argues that species intelligibilis is the principle from which intellectual operations proceed, not a derived product deposited in intellect and instrumentalized within them.
Chilean Art Music During the Cold War (1970-1990): Political Commitment, Exile and Democratizing Practices in Musics
(Université d'Ottawa | University of Ottawa, 2026-10-01) Rodriguez Mayen, Sebastian; Moore, Christopher Lee
This thesis examines the work of Chilean composers during the turbulent period between 1970 and 1990, spanning the presidency of Salvador Allende and the subsequent coup d’état and dictatorship of Augusto Pinochet. The works produced during these years by Luis Advis (1935–2004), Gustavo Becerra-Schmidt (1925–2010), Celso Garrido-Lecca (1926–2025), and Juan Orrego-Salas (1919–2019) bear witness to Chile’s rapidly shifting political and cultural landscape, which forced many artists into exile or silence under the dictatorship. Some of these composers later collaborated with folk music ensembles to express solidarity during their exile, whether imposed or voluntarily embraced. Through selected case studies, this thesis argues that the musical output of these composers constitutes a cultural response to broader geopolitical forces shaping both highbrow and popular culture, particularly the power dynamics of the Global Cold War. By analyzing their lives and works, the study demonstrates how political developments in the Global North influenced cultural production in the Global South, while also highlighting the varied forms of resistance — both overt and covert — and the resilience exhibited by composers and musicians in the Global South. These dynamics extended beyond exile to include the imposition and adaptation of dominant musical styles, practices of cultural diplomacy between host and home countries, and negotiations of indigeneity in artistic expression, all of which affected the composers examined in this study. Accordingly, this thesis considers not only the musical characteristics of these works but also the historical, political, and cultural conditions that shaped their creation. In doing so, it presents these composers and their compositions as historically situated witnesses to their time and place.
Development of a Solid-State Nanopore Platform Toward High-Throughput, Ultra-Sensitive, and Robust Single-Molecule Analysis of Nucleic Acids and Proteins
(Université d'Ottawa | University of Ottawa, 2026-10-01) Bouhamidi, Mohamed Yassine; Tabard-Cossa, Vincent
Solid-state nanopore sensors consist of a nanoscopic hole in a thin free-standing dielectric film (a membrane) bridging independent reservoirs of salt solution to interrogate the analytes present therein. Nanopores have demonstrated promising results in applications spanning DNA sequencing, biomarker detection, information storage and energy harvesting. Recently, researchers in the field have aimed to interrogate proteins with enough precision to extract their sequences. Despite their versatility, solid-state nanopores have advanced slowly experimentally due to obstacles and knowledge gaps that need to be explored. A few challenges are addressed in this thesis, attempting to provide insight for future steps in this direction, namely: 1) extracting surface charge density is key to studying the effect of membrane material properties on nanopore transport, fabrication conditions and subsequent chemical functionalization, 2) unwanted adsorption between the biomolecules and the sensor’s surface during the electrophoretic capture and translocation process hinders sensing performance and results in clog events, 3) small proteins or DNA nanostructures can be challenging to fully resolve, leading to missed or attenuated molecular event signatures, and 4) reducing membrane thickness to enhance the signal-to-noise ratio and the spatial resolution leads to faster sensor degradation over time for SiN. For the first objective, I present an experimental characterization platform capable of measuring the surface charge density of silicon nitride as a membrane material. The platform allows high-pressure streaming current measurements in the picoampere range, providing enough resolution to extract the zeta potential and surface charge density of new materials. Next, I explore an alternative anti-fouling protocol for the possibility of increasing sensing time while interrogating long and flexible single-stranded DNA (ssDNA). This analyte clogs the sensor in less than 15 seconds, while after surface modification, we collect relevant data for ⁓45–60 minutes before the first clog event. This improved protocol preserves noise performance comparable to pristine nanopores, even after surface modification. Furthermore, I evaluate the surface properties of these modified nanopores to confirm the successful binding of the polymer on the surface through zeta potential measurements. Moreover, I develop a trapping procedure that takes advantage of the surface characterization platform to reduce the translocation velocity of complex analytes, thus investigating pressure-voltage actuation for analytes of known velocity while determining the impact of this mode of translocation on dwell time. This actuation approach provides an up to 6× reduction in translocation velocity for DNA nanostructures and proteins respectively, facilitating the extraction of high-fidelity event signatures. Finally, I perform an exploration of nanopore membrane microfabrication processes and materials to improve signal amplitude while reducing noise limitations. Here, I present an alternative deposition approach for SiN thin films with a lower thermal budget, namely ion beam deposition (IBD) compared to the traditional Low-Pressure Chemical Vapor Deposition (LPCVD). Independently, I explore the properties of a sub-5 nm annealed Hafnium oxide (HfO2) membrane deposited by Atomic Layer Deposition (ALD), supported by an LPCVD SiN, in terms of film stability and sensing performance. Future work involves combining the lower thermal budget SiN deposition as a mechanical support for a sub-3 nm ALD HfO2 membrane. This approach will offer an ultra-thin solid-state nanopore architecture with reduced degradation, enhanced signal-to-noise ratio, and bypass the annealing step due to the temperature mismatch between depositions. Ultimately, my goal is to pave the way for more efficient and sensitive nanopore-based technologies, contributing to the fields of genomics, proteomics, and beyond.
Behavioral Apathy and its Relationship with Physical Activity, Affective Attitudes, and Motor Cortex Excitability
(Université d'Ottawa | University of Ottawa, 2026-10-01) Farajzadeh, Ataallah; Boisgontier, Matthieu
Apathy is a multidimensional syndrome characterized by diminished motivation and reduced goal-directed behavior. Although apathy is commonly studied in neurological and psychiatric populations, it is also observed in otherwise healthy adults and may represent an important barrier to engagement in physical activity. Because physical activity requires effort, action initiation, and persistence, individuals with higher levels of behavioral apathy may be less likely to initiate and maintain active behavior. Despite growing interest in the relationship between apathy and physical activity, the behavioral and neurophysiological mechanisms underlying this association remain poorly understood. This thesis examined the relationship between behavioral apathy, physical activity, affective attitudes toward physical activity, and motor cortex neurophysiology. Across four complementary studies, behavioral and neurophysiological pathways that may contribute to reduced physical activity in individuals with higher apathy were investigated. Study 1 is a systematic review and meta-analysis examining the association between apathy and physical activity across clinical and non-clinical populations. Study 2 examined whether intentions, explicit affective attitudes, and approach-avoidance tendencies toward physical activity mediated the relationship between behavioral apathy and physical activity in healthy adults. Study 3 is a systematic review and meta-analysis investigating the association between habitual physical activity and measures of motor cortex neurophysiology, including corticospinal excitability, intracortical inhibition, and intracortical facilitation. Study 4 used transcranial magnetic stimulation (TMS) to examine whether behavioral apathy was associated with these neurophysiological measures in healthy adults. Across the four studies, results demonstrated that apathy is associated with physical activity, but that this association is more strongly explained by motivational and affective processes than by resting-state motor cortex neurophysiology. The systematic review and meta-analysis showed a significant negative association between apathy and physical activity, with stronger associations in older adults and individuals with Parkinson’s disease. Behavioral analyses further demonstrated that higher behavioral apathy was associated with lower physical activity, partly through weaker intentions to be physically active and less positive affective attitudes toward physical activity. Individuals with lower apathy also showed stronger tendencies to approach physical activity stimuli and avoid sedentary stimuli, although these tendencies did not mediate physical activity behavior. In contrast, the neurophysiological studies showed no reliable associations between habitual physical activity and measures of corticospinal excitability, intracortical inhibition, or facilitation. Similarly, behavioral apathy showed negligible associations with these measures, with equivalence testing indicating that any potential effects were too small to be practically meaningful. These results suggest that the relationship between apathy and physical activity is primarily linked to motivational and affective mechanisms rather than stable differences in primary motor cortex neurophysiology. Specifically, higher behavioral apathy was associated with weaker intentions to be physically active and less positive affective attitudes toward physical activity, whereas neither habitual physical activity nor behavioral apathy showed meaningful associations with resting TMS-derived measures of corticospinal excitability or intracortical circuitry. Overall, this thesis refines the understanding of how apathy contributes to physical inactivity and highlights the importance of targeting motivational processes when designing interventions aimed at increasing physical activity engagement.