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OasisDB: An Oblivious and Scalable System for Relational Data
No full textWe present OasisDB, an oblivious and scalable RBDMS framework designed to securely manage relational data while protecting against access and volume pattern attacks. Inspired by plaintext RDBMSs, OasisDB leverages existing oblivious key value stores (KV-stores) as storage engines and securely scales them to enhance performance. Its novel multi-tier architecture allows for independent scaling of each tier while supporting multi-user environments without compromising privacy. We demonstrate OasisDB’s flexibility by deploying it with two distinct oblivious KV-stores, PathORAM and Waffle, and show its capability to execute a variety of SQL queries, including point and range queries, joins, aggregations, and (limited) updates. Experimental evaluations on the Epinions dataset show that OasisDB scales linearly with the number of machines. When deployed with a plaintext KV-store, OasisDB introduces negligible overhead in its multi-tier architecture compared to a plaintext database, CockroachDB. We also compare OasisDB with ObliDB, an oblivious RDBMS, highlighting its advantages with scalability and multi-user support
Exploring Menopause Through a Cultural Lens: Beliefs, Perceptions, and Experiences of Immigrant Punjabi Women in the Peel Region
No full textBackground: Menopause, despite being a pivotal stage in a woman’s life, is not a uniform experience. For immigrant Punjabi women, it is shaped by challenges influenced by their socio-cultural backgrounds, beliefs and social norms (Zou et al., 2023). In addition to the complexities introduced by migration, language barriers, social marginalization, and a lack of culturally relevant healthcare services often contribute to unmet needs of immigrant Punjabi women. While existing literature highlights how menopause is shaped by cultural and social factors, the experiences of South Asian immigrant women – particularly Punjabi women in Canada – remain unexplored. This study seeks to address this gap by exploring the beliefs, perceptions, and lived experiences of menopause among immigrant Punjabi women in the Peel Region, with the goal of informing how cultural humility and tailored healthcare approaches can enhance menopausal care for this population.
Research Questions: What are the beliefs and perceptions of immigrant Punjabi women in the Peel Region regarding menopause, and how do these shape their lived experiences of this transition? How do cultural practices, social norms, and immigration experiences influence the perceptions and management of menopause? What insights from their experiences can inform culturally responsive practices to better address their needs?
Methods: This qualitative study employed a Constructivist Grounded Theory (CGT) methodology to explore the experiences of menopause among immigrant Punjabi women aged 35 and older who have lived in the Peel Region for at least five years. Thirteen semi-structured interviews were conducted in either English or Punjabi, depending on participant preference, to ensure linguistic and cultural comfort. Interviews were audio-recorded, transcribed, and translated by the researcher to preserve cultural nuance. Data were analyzed inductively through the CGT process of initial coding, focused coding, and axial coding, allowing themes, and analytical categories, to emerge from participants’ narratives. Reflexivity and attention to positionality were prioritized throughout, recognizing the co-constructed nature of meaning between the researcher and participants.
Findings: Three interconnected core themes emerged from the data: (1) Silenced and Stigmatized: Cultural Taboos and Lack of Menopause Education, (2) Navigating Menopause in Isolation: Gender Roles, Migration, and Social Expectations, and (3) Seeking Support and Self-Advocacy: Pathways to Empowerment and Care. Participants described menopause as a topic shrouded in silence, often associated with shame and misinformation in their upbringing. Many women felt unprepared and unsupported, facing the transition in isolation while juggling familial responsibilities, caregiving roles, and the pressures of migration. However, some participants emphasized the importance of informal peer networks and expressed a desire for culturally safe, linguistically appropriate, and holistic care. These narratives reflected a tension between traditional cultural expectations and the evolving understanding of health and aging in a new socio-cultural context.
Conclusions: This study provides an in-depth, intersectional understanding of how immigrant Punjabi women experience menopause within the complex contexts of culture, gender, and migration. The findings underscore the urgent need for culturally responsive healthcare services that acknowledge the social realities and cultural frameworks of immigrant communities. By promoting cultural humility among healthcare providers and engaging in community-informed education initiatives, it is possible to reduce stigma, improve early intervention, and support immigrant women in navigating menopause with dignity and agency. This research contributes to the broader discourse on reproductive aging and equity in healthcare by centering the voices of a marginalized population whose experiences have been largely overlooked
Between Popular Cultural Authorship and Post-Scholarly Criticism: The Structural Analysis of the Digital Video Essay Form
No full textThis dissertation analyzes the digital video essay form on YouTube as a recent communicative and communal phenomenon, emphasizing the historical roles academic scholarship and popular cultural production have played in its emergence. On the one hand, by theorizing what I call ‘post-scholarly’ criticism, I explore and outline the potential influences of academic thought on the contemporary generation of former and current students, who produce video essays for public consumption on this platform. With some of them reaching over one million views, these video essays have become an immensely popular cultural critical genre on English-speaking YouTube, which often mobilizes concepts, contexts, and methods commonly associated with the humanities and liberal arts disciplines. By often expressing their left-leaning views in their analysis of popular cultural phenomena from artworks to digital aesthetics and discourse, today’s digital author-critics reproduce scholarly concerns that once famously marked the ‘radical’ cultural turn in the 1980s and onward. Specifically, video essayists often generate cultural criticism of mass-produced artworks / popular cultural trends and utilize the tools of critical theory to address systemic, institutional and political issues that they identify in contemporary corporate cultural industries as well as in digital cultural consumption and production. By examining this digital genre, I suggest that these critics rely on a loose scholarly episteme of intellectual fandom. Importantly, the move away from the professional academic domain encapsulated in the contemporary digital video essay form testifies to the structural process of deinstitutionalization taking place. In other words, I broadly argue that today’s digital post-scholarly critics publicly express a cultural and political trend towards deinstitutionalizing academic criticism and scholarship, which, in turn, calls for new articulations of the value of the humanities in academia today.
On the other hand, my dissertation also argues that contemporary digital authorship must be considered as a part of the historical trajectory related to popular amateur creative practices and new attractional multimedia mode of thinking. It has long been stressed that historically creative cultural practices situated around recombining various mediums prefigured the contemporary digital popular production witnessed on social platforms today. However, I suggest that it is important to consider the idea of the post-literary public sphere that has emerged as a direct result of mass cultural production in the west. I conceptualize the broad, post-literary public sphere in terms of the distinctive popular creative practices and communicative forms it has produced, arguing that contemporary digital authorship is an important emerging mode of self-articulation in today’s global western cultural context. The conversational, personalized, and immediately situated digital public genre of the video essay attributes heightened importance to individual self-expression as the pathway to broader social, cultural, and political dialogue. Thus, today’s digital authorship reminds us of the salient historical value of publicly circulating literary forms — their potential for generating a civic public sphere. Ultimately, by theorizing the digital video essay form through the constellation of post-scholarly criticism and popular cultural authorship, this dissertation offers a dialectical perspective for studying new modes of digital communication
Learning the Quantum, Scrambling the Universe
No full textThis thesis explores how quantum information behaves in extreme physical settings, from black hole interiors to noisy quantum devices.
First, we derive a thermodynamic relation linking gravitational shockwaves to microscopic deformations of the black hole horizon, illuminating the connection between quantum chaos and horizon area deformation.
Next, we explore the black hole information problem through the lens of holography, demonstrating how scrambling and recoverability emerge from gravitational backreaction in shockwave geometries.
Finally, we shift to quantum technologies, introducing noise-strength-adapted (NSA) quantum error-correcting codes discovered via hybrid machine learning. These non-stabilizer codes outperform conventional designs under amplitude damping and generalize to larger systems.
Together, these works reveal how quantum information unifies seemingly disparate domains, offering both conceptual insights into spacetime and practical tools for building resilient quantum systems
From Time
No full textThis thesis, From Time, explores the intersection of community and the built environment within Scarborough, Ontario, by examining the decommissioned Scarborough Rapid Transit elevated guideway as a site for adaptive reuse. Scarborough, one of six boroughs of Metropolitan Toronto, is shaped by post-WWII suburban sprawl, industrial zoning, and modernist ideals of efficiency. Its immigrant communities have adapted the industrial-residential landscape to meet their communal needs, both formally through the reuse of industrial buildings and informally through the occupation of the terrain vague.
Through personal reflections, historical research, and site analysis, this thesis investigates Scarborough’s social and communal dynamics. It explores how the remnants of the Scarborough RT infrastructure can reimagine public space, fostering a sense of communal identity. The design proposes the guideway’s reuse as a linear park with architectural infill, seeking to honour Scarborough’s history while providing a space that reflects its diverse cultural spirit.
This thesis contributes to ongoing discussions on community-centric design, offering a locally rooted, culturally responsive approach to redevelopment. The project emphasizes the need for spaces that support local social life, preserving the ingenuity and optimism that define the community of Scarborough
Confronting the Entity: The Implied Presence in Horror Cinema
No full textThis dissertation examines three horror films from the late 1970's: John Carpenter's Halloween (1978), Philip Kaufman's remake of Invasion of the Body Snatchers (1978) and Peter Medak's The Changeling (1980). The examination illustrates the importance of cinematographically-rendered negative space surrounding the films' villainous entities; the term this dissertation will propose in this context is the implied presence. The implied presence is key to not only establishing a distinction between terror (dread) and horror (revulsion), but also subverting the notion of a linear and finite path from terror to horror. The implied presence (that which is not seen on screen but implied) creates the opportunity for the viewer to create and engage with a more personal and individual confrontation with the villainous entity before it occurs visually on screen; this challenges and transcends the idea of subjectivity and the role of the voyeur for the viewer. This argument makes a critical connection between technical filmmaking practices and viewer participatory autonomy in the filmic experience that will show a higher level of intellectual and emotional/psychological control over how one views a horror or suspense film.
Michel Chion proposes the term "Audiovisual Contract" (Audio Vision, 1994) to explain how visual and sound in a film are separate cinematic elements temporarily working together, yet are accepted together by the viewer to be creating a sensory backdrop for a diegesis. In a similar way, the implied presence in both sound and image challenge the viewer to form a contract with the impending horror confrontation before it happens on-screen. This establishes the distinction between the notion of horror and the display of horror, which places the notion of horror more firmly in the psychological and emotional control of the viewer. In this way, the viewer becomes able to create an entity that is unique to each individual and not solely dictated by the screen.
This creates the platform for a pedagogical angle to this dissertation: learning how to watch a horror film, to understand why viewers fear them, can extend the medium's teaching value, and open the door for a larger and more comprehensive approach to cross-disciplined film study. This dissertation proposes a methodology for this approach in its study of technical filmic elements and narrative strategies. The three films examined were chosen because they best exemplify the catalysts for modern cinematic practice and expression. They encourage viewers to consider carefully the diegetic world but also the outside world that created them
The reliability and validity of a non-wearable indoor positioning system to assess mobility in older adults: A cross-sectional study
No full text© 2025 Rodrigues et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Background
Detecting early changes in walking speed can allow older adults to seek preventative rehabilitation. Currently, there is a lack of consensus on which assessments to use to assess walking speed and how to continuously monitor walking speed outside of the clinic. Chirp is a privacy-preserving radar sensor developed to continuously monitor older adults' safety and mobility without the need for cameras or wearable devices. Our study purpose was to evaluate the inter-sensor reliability, intrasession test-retest reliability, and concurrent validity of Chirp in a clinical setting.
Methods
We recruited 35 community-dwelling older adults (mean age 75.5 (standard deviation: 6.6) years, 86% female). All participants lived alone in an urban city in southwestern Ontario and had access to a smart device with wireless internet. Data were collected with a 4-meter ProtoKinetics ZenoTM Walkway (pressure sensors) with the Chirp sensor (radar positioning) at the end of the walkway. We assessed participants walking speed during normal and adaptive locomotion experimental conditions (walking-while-talking, obstacle, narrow walking, fast walking). We selected walking speed as a measure as it is a good predictor of functional mobility but also is associated with physical and cognitive functioning in older adults. Each of the experimental conditions was conducted twice in a randomized order, with fast walking trials performed last. For intra-session reliability testing, we conducted two blocks of walks within a participant session separated by approximately 30 minutes. Intraclass Correlation Coefficient(A,1) (ICC(A11)) was used to assess the reliability and validity. Linear regression, adjusted for gender, was used to investigate the association between Chirp and cognition and health-related quality of life scores.
Results
Chirp walking speed inter-sensor reliability ICC(A11) = 0.999[95% Confidence Interval [CI]: 0.997 to 0.999] and intrasession test-retest reliability [ICC(A11)=0.921, 95% CI: 0.725 to 0.969] were excellent across all experimental conditions. Chirp walking speed concurrent validity compared to the ProtoKinetics ZenoTM Walkway was excellent across experimental conditions [ICC(A11)=0.993, 95% CI: 0.985 to 0.997]. We found a weak association between walking speed and cognition scores using the Montreal Cognitive Assessment across experimental conditions (estimated β-value = 7.79, 95% CI: 2.79 to 12.80) and no association between walking speed and health-related quality of life using the 12-item Short Form Survey across experimental conditions (estimated β-value = 6.12, 95% CI: -7.12 to 19.36).Federal Economic Development Agency for Southern Ontario (FedDev) || Southern Ontario Pharmaceutical and Health Innovation Ecosystem (SOPHIE) || Chirp Inc
Disturbance Vulnerability Analysis and Reduction for Nonlinear Systems using Modes of Instability
No full textEngineered systems naturally experience large disturbances which have the potential to disrupt desired operation because the system may fail to recover to a desired exponentially stable equilibrium point (SEP). It is valuable to determine the mechanism of instability when the system is subject to a particular finite-time disturbance, because this information can be used to improve vulnerability detection, and to design controllers capable of mitigating these disturbances to enhance system resilience and ensure reliable performance, thereby reducing vulnerability.
For a large class of nonlinear systems there exists a particular unstable equilibrium point (UEP) on the region of attraction (RoA) boundary of the desired SEP such that the unstable eigenvector of the Jacobian at this UEP represents the mode of instability for the disturbance. Unfortunately, it is challenging to find this mode of instability, especially in high dimensional systems, because it is often computationally intractable to compute this particular UEP for a given disturbance. Consider a particular finite time disturbance applied to a nonlinear system which possesses a SEP representing desired behavior. The system is able to recover from the disturbance if its post disturbance initial condition (IC) lies inside the RoA of the desired SEP. In cases where the system fails to recover, the nonlinear mode of instability for the disturbance represents the subset of system dynamics most responsible for this failure to recover.
This thesis develops a novel algorithm for numerically computing the mode of instability for parameter-dependent nonlinear systems without prior knowledge of the particular UEP, resulting in a computationally efficient method. The key idea is to first consider the setting where the system recovers, and to average the Jacobian along the system trajectory from the post-disturbance state up until the Jacobian becomes stable. As the system approaches inability to recover, the averaged Jacobians converge to the Jacobian at the particular UEP, and can be used to extract the unstable eigenvector representing the mode of instability. Convergence guarantees are provided for computing the mode of instability, both for the theoretical setting in continuous time, and for the proposed algorithm which relies on numerical integration. Numerical examples illustrate the successful application of the method to identify the mechanism of instability in power systems subject to temporary short circuits.
Then a novel approach to control design for reducing disturbance vulnerability of nonlinear systems using knowledge of the mode of instability is developed. The main idea is to tune controller parameter values so as to drive the post-disturbance IC further inwards away from the RoA boundary by driving it in the direction opposite to the mode of instability. To achieve this, the problem is formulated as a nonconvex optimization problem, and an efficient algorithm is developed to solve it. Local convergence guarantees are provided for this method. Numerical examples illustrate the successful application of the method to reduce the vulnerability of power systems subject to temporary short circuits
Cosmic Frontiers: From the Origins to Gravitational Wave Astronomy
No full textIn this thesis, we present different aspects of cosmology, focusing on the early universe, large scale structure formation, and gravitational wave astrophysics. We begin by introducing cosmological perturbation theory as a framework to describe the origin of the universe, emphasizing its observational implications. We discuss early universe models and, motivated by the avoidance of singularities, we propose bouncing cosmologies. In particular, we discuss the Cuscuton model; which modifies gravity to generate a bounce without introducing new degrees of freedom, provides a smooth transition between contraction and expansion, and generates scale-invariant entropy perturbations. We analyze scalar perturbations and demonstrate that the model remains stable and weakly coupled. Additionally, we compute three-point functions, showing negligible non Gaussianities on observable scales, with potential signals arising from the conversion of isocurvature to curvature perturbations.
Building on this foundation, we investigate the formation of large scale structures and study bias parameters that describe the statistical distribution of dark matter halos and galaxies. We extend this analysis to gravitational wave (GW) sources, introducing the GW bias parameter. We propose a methodology to link binary black hole (BBH) mergers to their host galaxies using phenomenological GW host-galaxy probability functions. These functions are constructed based on observed astrophysical properties of galaxies, including stellar mass, star formation rate, and metallicity. We calculate the GW bias using the angular power spectrum for photometric surveys and the 3D power spectrum for spectroscopic surveys. We find that the GW bias depends on the parameters of the host-galaxy probability functions, which are linked to the formation channels of BBHs. Future measurements of the GW bias could provide insights into the astrophysical processes governing GW sources and their relation to large-scale structure.
Lastly, we emphasize that cosmology may be entering a golden era, driven by a wealth of upcoming experiments, including the next generation of Cosmic Microwave Background (CMB) telescopes, galaxy surveys, and GW detectors. These experiments have the potential to provide hints for modifications to ΛCDM cosmology, the nature of dark matter and dark energy, black hole physics, and possible deviations from general relativity, paving the way for new theoretical and observational breakthroughs
Combinatorial Aspects of Feynman Integrals and Causal Set Theory
No full textThis thesis consists of two distinct sections, the first highlighting causal set theory (CST) and the second focusing on Feynman period estimation. This work specifically covers how discrete structures from algebraic combinatorics can be applied to problems from physics, and how we can use computational tools and techniques to help solve these problems from a mathematical perspective.
In the first part of the thesis, we introduce CST, an approach to quantum gravity that focuses on how events in spacetime are causally related to one another. In CST, discretized spacetime is given by a locally finite poset. A significant portion of this section focuses on covtree, which allows us to evolve such a discrete spacetime, in a way that does not depend on arbitrary labelling. However recognizing nodes of covtree involve solving a particular downset reconstruction problem. To attack this we define a graph that compares downsets that differ by exactly one element, with a particular focus on the order dimension two case. This section of the thesis sheds light on evolving a spacetime by constructing future elements within the covtree framework. Reconstructing spacetime in this way will allow for researchers to advance our understanding of covtree’s structure and improves causal set theory as an approach to quantum gravity.
In the second part, we provide an introduction to Feynman periods, explaining their significance in quantum field theory (QFT) calculations. We will discuss how machine learning models, such as linear and quadratic regression, and graph neural networks, can be applied to Feynman graphs and their properties, to predict the Feynman period. Even simple techniques like linear regression, on graph parameters only, which do not consider the graph structure directly, can make highly accurate predictions of Feynman periods. The work presented in this section, done jointly with Dr. Paul-Hermann Balduf, is published in the Journal of High Energy Physics. This research has significant implications for QFT computations, which can become computationally infeasible at large scales, and facilitates further exploration in particle physics