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.

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    Quantum Correlation Imaging Through Scattering Media
    (Université d'Ottawa / University of Ottawa, 2026-11-02) Hubble, James; Karimi, Ebrahim
    This thesis explores the use of spatially entangled photon pairs to enhance imaging contrast through weakly scattering media. Particular attention is paid to how the spatial correlations of biphotons survive or degrade on propagation through a scattering medium, and to how coincidence detection combined with post-selection on those correlations can separate ballistic from scattered light. Because ballistic biphotons preserve their source correlations while scattered pairs do not, retaining only the coincidences consistent with those correlations enhances contrast relative to conventional single-photon imaging and simultaneously rejects uncorrelated background. We demonstrate this enhancement, quantified through the modulation transfer function, in two configurations - one in which both photons from the pair are affected by the scattering medium, and one in which only a single photon is scattered while its partner follows an undisturbed reference path, directly to a spatially-resolving detector, which partially compensates for the resulting increase in shot noise by combining events from several post-selection windows. In the first chapter, a brief overview of the field is provided, introducing the concept of contrast, the problem of scattering, and the degrees of freedom of light. The second chapter develops the background necessary to understand the experiment: the quantization of the electromagnetic field, quantum entanglement, spontaneous parametric down-conversion and the spatial and temporal correlations of the biphoton state, and the quantum imaging configurations that exploit them. In the third chapter, the experimental implementation and results are presented, followed by the article reporting the method and its demonstration through weakly scattering media. Finally, the conclusions and outlooks are outlined in the last chapter.
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    Cellular Mechanisms Determine Soma-dendrite Correlation
    (Université d'Ottawa | University of Ottawa, 2026-10-30) Huang, Yusheng; Naud, Richard
    Neurons receive synaptic inputs across spatially separated compartments, and the relationship between dendritic processing and somatic output can shape how information is represented in spikes and bursts. However, it remains unclear how compartmentalization within a single neuron interacts with multiplexing, in which multiple input streams are represented simultaneously in a single spike train. This thesis uses a two-compartment neuron model to study how dendritic and somatic dynamics jointly support multiplexed coding. The model separates dendritic integration from somatic spike generation while allowing interaction in both directions through forward dendrite-to-soma drive and spike-triggered soma-to-dendrite feedback. Compartmentalization is quantified operationally using the Pearson correlation between dendritic and somatic membrane voltages, and multiplexing is quantified by the extent to which two output features, event rate and burst fraction, track two compartment-specific input streams. The results indicate that multiplexing is strongest at an intermediate level of compartmentalization, as measured by soma-dendrite voltage correlation: when this correlation is high, event rate and burst fraction become less specific to their corresponding input streams, whereas when this correlation is low, dendritic and somatic activity are less effectively linked. Finally, the thesis introduces a compact metric to quantify how noise, forward dendrite-to-soma drive, and spike-triggered soma-to-dendrite feedback shape the relationship between compartmentalization and multiplexing. This work offers a perspective on the design principles of neural computation and may inform future modeling of signal processing in complex neural structures.
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    Investigating Temporal Resolution in Children with Listening Difficulties Using a Novel Multi-Deviant Paradigm
    (Université d'Ottawa | University of Ottawa, 2026-10-30) Omidvar, Shaghayegh; Koravand, Amineh
    Auditory temporal resolution is the ability to detect rapid changes in sound. It is often measured using gap-detection tasks, in which a listener detects a brief silent interval within a continuous or long-duration sound. Gap detection is important for speech perception because many speech cues depend on fine temporal information. However, behavioural gap-detection tasks require attention, motivation, and active responses. These factors are especially important when testing children, including those with auditory processing disorder (APD), because poor behavioural performance may not always reflect a pure auditory temporal-processing deficit. The present thesis examined automatic auditory gap detection using event-related potentials (ERPs). The main focus was the deviant-related negativity (DRN), an electrophysiological response elicited by a gap deviant. The thesis investigated whether the temporal position of a gap affects the DRN and whether a time-efficient multi-deviant paradigm can be used to study multiple gap onset times within a single recording sequence. Behavioural and electrophysiological gap detection were examined in adults, typically developing (TD) children, and children with APD. Participants completed passive electroencephalography (EEG) recordings while watching a silent subtitled video and ignoring the auditory stimuli. The standard stimulus was a 500-ms broadband-noise burst. Deviants were created by inserting a silent gap of either 10 or 30 ms at different onset times, ranging from 15 to 400 ms after stimulus onset. In a separate behavioural task, participants actively detected the occurrence of the gap. There was no significant difference in DRN amplitude between the multi- and single deviant paradigms. Across groups, DRN amplitude was larger for 30-ms than for 10-ms gaps and decreased when the gap occurred later in the stimulus. In adults, the DRN was reduced for gaps occurring at 300 and 400 ms. In TD children, this temporal limitation was stronger, with reliable DRNs mainly observed for early-occurring gaps. Behavioural performance was generally high, but children performed more poorly than adults. Children with APD also showed poorer behavioural gap detection than TD children. However, their overall DRN amplitude was not consistently reduced, although less stable responses were observed in some conditions. Overall, this thesis showed that automatic neural detection of gaps is affected by both gap duration and gap onset time. The findings support the idea that auditory deviance detection is limited by a short temporal integration window. This limitation appears stronger in children than in adults. In children with APD, poorer behavioural performance may partly reflect task demands or attention rather than a consistent deficit in automatic auditory change detection. The multi-deviant gap paradigm may therefore be considered in future work as a time-efficient approach for studying auditory temporal processing in adults, children, and clinical populations.
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    Left Out of Sight: Exploring Stigma in Healthcare Accommodations for Canadians with Low Vision
    (Université d'Ottawa | University of Ottawa, 2026-10-30) Macdonald, Isabella; Fraser, Sarah
    Background/Rationale: Older adults with low vision or blindness face healthcare barriers that extend beyond service access, including stigma, ageism, and inconsistent accommodations. Little is known about how these barriers operate within Canadian healthcare settings. Research Questions: What do older adults report when requesting accommodations, and how do provider interactions reflect stigma and ageism? Objective: To explore how older adults with low vision and blindness experience requesting accommodations and interacting with providers in the Canadian healthcare system, primarily in Ontario, where 14 of the 15 participants resided. Methods: Semi-structured interviews were conducted with 15 adults with low vision or blindness who had accessed Canadian healthcare within the previous 10 years. Participants were recruited through community, retiree, and disability organizations. Results: Seven themes were identified. Continuity of care provided the context against which other experiences were measured. Three challenges were described: inconsistent accessibility, clinician and staff gaps, and stigma. Participants responded through family advocacy and self-advocacy, and identified recommendations for recognition, systemic reform, and training. Accommodations were available when requested but were rarely anticipated, which transferred the work of obtaining accessible care to participants and their families. Conclusion: Healthcare in Ontario, where most participants resided, accommodated participants when asked but did not anticipate their needs. Findings inform more equitable, age-inclusive, and disability-conscious healthcare practice.
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    Comparable Differentials, Distinct Architectures. Parliamentary Mediation, Emiri Concentration, and The Citizenship Differential in Kuwait and Qatar.
    (Université d'Ottawa | University of Ottawa, 2026-10-30) El Idrissi, Meryem; Vairel, Frédéric
    Kuwait and Qatar allocate to their citizens similar income entitlement over non-citizens; however, they constitute it in different ways. This thesis examines that entitlement, which it conceptualizes it as the citizenship differential, across two closely paired, resource-dependent Gulf monarchies distinguished by one institutional variable, given that Kuwait maintained an active elected Assembly during the period studied, while Qatar did not. Disaggregating official household survey data through five distinct channels (employment, asset income, government transfers, subsidies and legal restrictions on non-citizens), using four Kuwaiti survey waves (1999/2000 – 2019/2021) and one Qatari survey for 2006/07, the analysis inclusive of imputed rent yields disparities of 2.72 times in Qatar and 2.91 times in Kuwait. Qatar’s differential is driven from state transfers and subsidies and Kuwait’s stems from employment. Therefore, their near-identical totals are the product of arithmetic cancellation rather than a shared institutional design. Meanwhile, non-citizens across both jurisdictions converge on the same floor due to the kafāla system. Due to Qatar’s limited data disclosure constituted of only one survey, the comparison rests on the two closest survey waves. This study advances a channel-by-channel disaggregation of the income gap, while extending existing institutional frameworks of welfare stratification from class cleavages to the divide between citizens and expatriates.