VictorJuiz/thesis huggingface dataset:
CMP: A Filesystem Metadata Compression Framework For Data Intensive Workloads
Keywords: Filesystem
Memory Compression
Metadata

The growing demand of data-intensive applications, represented by machine learning, coupled with rapidly expanding datasets, have precipitated significant challenges in metadata caching system for large-scale, distributed filesystems. Traditional in-memory metadata caches are increasingly inadequate due to the sheer volume of files and the non-localized data access patterns typical of such workloads. To address these challenges, this thesis presents the Compressed Metadata Pool (CMP), a novel, mid-layer solution that compresses the in-memory inode cache for distributed filesystems. Designed for seamless integration, CMP imposes no modifications on client-side software, server hardware, or stored data, offering a modular upgrade path for existing inode-based filesystems. Structurally, CMP adopts a block-based architecture, allowing for the accommodation of multiple compression algorithms, thereby providing adaptability to a range of workload characteristics. Specifically, CMP leverages the Base-Delta-Immediate (BDI) compression algorithm, striking an optimal balance between compression efficiency and latency overhead, a feature especially beneficial for machine learning tasks. To resolve the decompression and recompression issue that may arise during inode updates, CMP employs the extra slots for few incompressible inodes after updates. Further enhancing its robustness, we introduce two supplementary optimizations—grouping and relaxation—that target dynamic datasets. Implemented and evaluated within the Lustre filesystem, CMP’s performance under simulated machine learning training workloads revealsup to 3.66× improvement in metadata cache capacity while maintaining a latency overhead of less than 15%. Overall, CMP offers an effective and modular approach to extend metadata services for filesystems coping with large-scale datasets and data-intensive workloads.
Clinical and Functional Neuroimaging Characteristics of Older Adults with Subjective Cognitive Decline
Keywords: Default Mode Network
Functional Magnetic Resonance Imaging
Memory Complaints
Memory Functioning Questionnaire
Psychological Symptoms
Subjective Cognitive Decline

Subjective cognitive decline (SCD) is conceptualized as a preclinical stage of Alzheimer's disease (AD) in which individuals perceive memory decline despite normal cognitive performance. This thesis aims to identify clinical and functional neuroimaging markers to characterize SCD individuals before AD onset. SCD and Mild Cognitive Impairment (MCI), a prodrome to AD, reported increased frequency and severity of memory lapses and health anxiety compared to the cognitively unimpaired (CU) group. SCD reported increased state and trait anxiety and neuroticism compared to the CU group. SCD individuals who have perception of lower memory ability expressed more health anxiety, trait anxiety, and neuroticism. Within the SCD group, reduced posterior default mode network (DMN) and increased anterior DMN functional connectivity were observed. Limitations include lacking AD biomarkers or longitudinal follow-up to establish SCD as a preclinical AD group. This thesis serves as a platform to continue developing markers of SCD due to preclinical AD.
Growth Factor Regulation of Neuroblastoma Migration and Invasion
Keywords: Biophysics
Cancer
Neuroblastoma

Neuroblastoma (NB) is the most common extracranial pediatric cancer with a five-year survival rate of less than 50%. It arises from neural crest precursors in tissues such as the adrenal gland. Metastatic NB is often fatal with common sites including bone, bone marrow and brain. Our laboratory previously developed a mouse model of NB to study metastasis to the bone and the brain, isolated tumor cells from these metastatic sites and identified genes regulating their metastatic behavior. Since neural crest-derived cells often use receptor tyrosine kinases (RTKs) and their ligands to proliferate and migrate, I hypothesized that NB cells also use these proteins to metastasize. To address this, I performed mass spectroscopy analysis of NB cell surface proteins and scRNA-seq to identify RTKs and their ligands enriched in hypermetastatic NB cells as compared to less metastatic parental cells. I identified four RTKs, PDGFRA, PDGFRB, EGFR, and FGFR1 and found that the PDGFRB ligand PDGFBB mediated the migration and invasion of the hypermetastatic cells without markedly affecting the parental cells. These findings suggest that NB cells use PDGF to mediate part of the metastatic process.
The Relationship between Compulsory Schooling Policy, Educational Equity and Student Achievement in Turkey and Portugal
Keywords: Compulsory education policy
equity
Portugal
socioeconomic status
student achievement
Turkey

AbstractCompulsory schooling laws are used as a policy tool for promoting educational equity and access to education, especially for disadvantaged students. However, the evidence regarding the impact of these laws on decreasing inequalities is not consistent. This paper uses PISA data from 2009 and 2015—before and after compulsory schooling policy changes in Turkey and Portugal in 2012—to examine changes in the math achievement of students with low and high socioeconomic status (SES). The results suggest the impact of compulsory schooling laws can vary depending on the context as SES achievement gaps decline in Turkey but do not change in Portugal. As there is little previous quantitative research conducted about these reforms in Turkey and Portugal, this study will contribute to the comparative literature by providing recent evidence about the role of compulsory schooling policy change on socioeconomic inequalities in middle-income countries with their unique challenges and opportunities.
Roofstock and the Millennial Remote Landlord: A Case Study of Post-crisis, Platform-mediated Retail Investment in Single-family Rental Housing
Keywords: Millennials
Platform real estate
Property Technology
Remote landlord
Single-family rental housing

Millennials are the generation of “forever renters”: a cohort of aspiring homeowners facing exorbitant housing prices and stagnant wages. With homeownership out of reach for many, millennial consumers are being targeted to become investors in the single-family rental (SFR) market. Digital property technologies – online platforms for real estate investment known as “PropTech” – are creating bespoke marketplaces for young, first-time investors to become digital landlords in lieu of personal homeownership. This research focuses on one firm, Roofstock, an Oakland-based PropTech startup recently valued at $1.9 billion, which is incorporating young, inexperienced investors into the SFR market with retail consumer products. I explore the platform business model in structuring digital rentier relations for remote landlords and tenants and the significance of platform technologies naturalizing high-risk digitally-mediated investments. Finally, I discuss the implications for a growing class of millennial remote landlords in leveraging market power and building housing wealth through alternative investing pathways.
Occupancy Grid Mapping via Resource-Constrained Robotic Swarms: A Collaborative Exploration Strategy
Keywords: exploration
motion control
occupancy grid map
swarm mapping
Swarm robotics

This Thesis considers the use of robotic swarms with limited exteroceptive and inter-robot sensing capabilities for exploring and mapping unknown environments. It presents a novel collaborative exploration strategy that directs the resource-constrained swarm toward unexplored areas in the environment by dividing the swarm into two teams: landmark robots and mapper robots, respectively. The former directs the latter toward ‘promising’ frontiers in the environment enabling efficient frontier-based exploration. The landmark robots are optimally positioned to maximize new information added to the map while also adhering to connectivity constraints. The mapper robots are decentralized and use random motion to explore the local area surrounding the landmark robots. Through this decoupling of the swarm into two separate teams, directing the swarm to new areas of the environment can be addressed separately from exploring and mapping that new area. The performance of the exploration and mapping strategy has been validated through extensive simulations.
Brain-Cognition Associations in Late-Life Depression or Mild Cognitive Impairment: An Analysis of Gray and White Matter Integrity
Keywords: Cognition
Depression
Geriatric
Magnetic resonance imaging
Mild cognitive impairment
Neuroimaging

Most older adults with late-life depression (LLD) exhibit cognitive impairment and a third meet diagnostic criteria for mild cognitive impairment (MCI). While LLD is a risk factor for developing Alzheimer’s dementia (AD), the mechanisms remain unclear. In Study 1, we systematically reviewed the literature to synthesize the published associations between structural brain alterations and cognition in LLD or LLD+MCI. The current literature is characterized by limitations: basic cognitive measures, univariate models, small sample sizes, and quasi-absence of participants with LLD+MCI. These findings guided the design of Study 2: we assessed the multivariate associations between structural brain alterations and cognition in a sample (N=283) of participants with LLD, MCI, or LLD+MCI, and controls. Gray matter atrophy in specific regions predicted worse memory, language, and processing speed; global reduced white matter tract integrity predicted worse executive function and processing speed. These findings remained significant in MCI/LLD+MCI, but not LLD or HC groups.
LiNO₃-Poly(vinyl Alcohol) (PVA) Solid Polymer Electrolytes: Properties, Longevity and Application for Electrochemical Capacitors
Keywords: electrochemical capacitors
LiNO3-PVA
Polymer electrolyte
Solid-state electric double-layer capacitors
Supercapacitors

Neutral pH polymer electrolytes are promising for future thin solid energy storage technologies including electrochemical capacitors (ECs), enabling environmentally benign, leakage-free and flexible form factors without bulky packaging. In this thesis, LiNO₃-poly(vinyl alcohol) (PVA) polymer electrolyte was studied and compared to the liquid baseline. Examining ionic conductivity at ambient and low temperatures, an optimal LiNO₃-PVA composition with a molar ratio of 2,500:1 demonstrated high ionic conductivity of 40 mS cm-1, and remained functional at -40 °C. The long-term stability of the polymer electrolytes revealed a strong connection between electrolyte water content and ionic conductivity. Raman spectroscopy indicates that the chemical bonding, structure, and conductivity of LiNO₃-PVA are linked to aqueous LiNO3 concentration rather than PVA. Key water levels in the electrolyte have been identified. The enabled solid electric double layer capacitors (EDLCs) had a wide voltage range of 1.6 V and 76% capacitance retention at -40 °C, surpassing aqueous counterparts.
Distinct Neurodevelopmental Signatures of Sex-Specific Transcriptome-Based Polygenic Risk Scores for Depression
Keywords: depression
development
neuroimaging
polygenic risk score
sex-specific
transcriptomics

Post-mortem gene expression profiling reveals distinct transcriptomic signatures of major depressive disorder (MDD) in each sex. Leveraging these data, we sought to develop female- and male-specific transcriptome-based polygenic risk scores (tPRS-F and tPRS-M, respectively) and evaluate their impact on regional cortical thickness, cortical surface area, subcortical volume, and depressive symptoms at baseline and 2-year follow-up in a developmental sample of 5002 adolescents (46.6% female, aged 8.9–11.0). In males, tPRS-M was associated with higher symptoms at both time points and thicker posterior cingulate at follow-up. In females, at follow-up tPRS-F was associated with lower volumes of the accumbens area, caudate, and hippocampus, the latter two of which mediated an indirect tPRS-F effect on symptoms. For each score, no effects emerged in the opposite sex. Our findings suggest that sex-specific depression-like shifts in gene expression may contribute to a vulnerability phenotype for future MDD risk via distinct mechanisms in both sexes.
Reactions and Fate of Alkyl-Substituted Polycyclic Aromatic Hydrocarbons (AlkPAHs) in the Atmosphere
Keywords: Alkyl substituted polycyclic aromatic hydrocarbons
Heterogeneous oxidation
ozone
polycyclic aromatic compounds

Recent studies have reported greater abundance of alkyl-substituted polycyclic aromatic hydrocarbons (AlkPAHs) than unsubstituted polycyclic aromatic hydrocarbons (PAHs) in Canada, suggesting their potential importance to environmental health. The levels and impacts of AlkPAHs depend on their oxidative fate, emission factors and several others. Homogeneous oxidation of AlkPAHs has been shown to be faster than PAHs; however, less is known about heterogeneous oxidation rates. In this study, several AlkPAHs and PAHs were exposed to ozone at various time intervals. Observations showed a decrease in AlkPAHs concentrations with increasing ozone concentration with second order kinetics for all compounds. Additionally, AlkPAHs reacted faster with ozone than their analogous PAHs. Moreover, oxidation rates depended on molecular structure with larger alkyl groups increasing the reaction rate with ozone. This thesis highlights the effect of alkylation on the oxidation rate of PAHs which informs the transformation rate of AlkPAHs in the atmosphere in comparison with PAHs.
Design, Testing, and Verification of Communication Systems for Microsatellite Missions
Keywords: Communication Systems
Microsatellite
Radio Frequency

Microsatellite missions have enabled greater access to space for many, especially for commercial and research applications. The Space Flight Laboratory provides microsatellite platforms that support the goals of such satellite missions. The platforms include the communication subsystem, which allows a connection to be maintained between the operators on the ground and the satellite in orbit. This thesis presents the author's contributions to the communication subsystem of two missions. Firstly, the testing of components within the communication system is presented, identifying test criteria, observations, and results. Secondly, a verification method for the process of estimating the strength of the signal received by the satellite is developed using data collected from satellites in orbit. The method is then used to analyze the performance of a mission. Finally, the preliminary design of a communication system is presented, including considerations for mission-specific requirements.
Queer Visual Practices and Cross-strait Gallery Space
Keywords: Affect
China
Cold War
Queer Marxism
Taiwan
Visual Culture

This thesis posits that queer visual practices in mainland China and Taiwan offer not just a mode of critique but a mode of collective resistance across the Taiwan Strait that can enact queer ways of living. The current framework for understanding queer visual practices in the region is built around a representational critique of political and cultural institutions. While this critique offers a lens onto the institutions that can make queer lives unlivable, there is still a need for alternative frameworks that consider the complexity of queer experiences in the region. My thesis addresses this gap by starting with the understanding that cultural and political institutions are deeply engrained in the political and economic flows that cross the Taiwan Strait. By pulling together an archive of exhibitions, documentaries, landscapes, and autoethnographic data, this thesis reads queer visual practices across mainland China and Taiwan as a practice beyond “art” with the potential to imagine alternatives to the contemporary cold war political and capitalist economic structures of violence.
Visual Rehabilitation in a Pediatric Population of Patients with Homonymous Hemianopia: A Pilot Study on Immersive Virtual-Reality Stimulation (HH-IVR)
Keywords: Clinical Trial
Hemianopsia
Neuroscience
Pediatric
Virtual Reality
VR

The purpose of this pilot study is to investigate the feasibility and potential treatment effectiveness of Re: Vision, a novel virtual reality (VR) rehabilitation treatment, in children with tumour-induced homonymous hemianopsia (HH), a field loss deficit in the same halves of the visual field of each eye. Ten pediatric patients with HH received 15 minutes of home-based VR stimulation sessions every two days for six weeks, during which they wore a head-mounted display (Oculus Quest 2, Meta) and were tasked to track the movement of a moving target ball in a 3D virtual space. All participants completed the treatment without adverse events—improvement in binocular visual perception and reading speed after treatment was observed in treatment responders. Preliminary results of this pilot study suggest the feasibility and potential treatment effectiveness of the Re: Vision in pediatric patients with tumour-induced HH, which can be further explored and optimized in future studies.
Establishing a Major Depressive Disorder Patient to Neural Organoid Pipeline
Keywords: iPSC Reprogramming
iPSCs
Major Depressive Disorder
Neural Organoid
Organoids

Major Depressive Disorder (MDD) is a debilitating mood disorder and one of the leading causes of disability worldwide. Advancements in induced pluripotent stem cell (iPSC) technology offers the opportunity to study the complex genetic background of MDD patients in vitro. The aim of my project is to establish a pipeline for efficient reprogramming of iPSCs from MDD patients and consistent generation of neural organoids, a 3D model which recapitulates cellular and structural features of the human brain. We recruited a hospitalized cohort of MDD in-patients from St. Joseph’s Healthcare (McMaster, Hamilton, ON) and collected whole blood for reprogramming to iPSCs. Age, sex and demographically matched control iPSC lines were obtained. To generate iPSC-derived neural organoids, we developed an optimized protocol which includes dual SMAD inhibitor-guided neural induction, resulting in the proper development of neuroepithelial tissue and morphology through development. Through immunohistochemistry, neural organoids exhibit markers for neurons and astrocytes, and have rudimentary cortical cytoarchitecture. Profiling of neural proliferation in patient-derived and control neural organoids using Ki67 and BrdU co-immunostaining show no differences between groups. The work presented here lays the groundwork for vital future research in MDD involving disease phenotyping, drug discovery and personalized medicine.
The Dynamics of Ecology, Demography, Dispersal, Habitat Selection, and Life History in a Crayfish Cambarus bartonii Population in Ontario
Keywords: crayfish
dispersal
habitat selection
life history
population ecology

A fundamental goal in ecology is to understand how organisms operate and organize in ecosystems. Yet, there is much to be gleaned about the underlying drivers of these ecological mechanisms. I used mark-recapture methodology to study a Cambarus bartonii population in Ontario. I examined ecology, demography, dispersal, habitat selection, their underlying drivers and temporal patterns, and their ecological implications for this population. I identified patterns encompassing capture frequency, size classes, length-weight relationships, life history, and population size estimates. I documented considerable crayfish dispersal within a short period of time, uncovered patterns relating dispersal and life-history traits, and habitat selection and its underlying processes, which helps our understanding of how organisms disperse and choose habitats. My research has implications for understanding population dynamics and resource selection in a changing world, given that crayfish are characterized as keystone species, and they are of particular concern as both invasive and endangered species globally.
And the Jordan Will Flow as a River of Peace Over Us All: The Music of Ofra Haza in Cabaret
Keywords: Cabaret
Israel
Judaism
Kabbalah
Music
Ofra Haza

The music of Ofra Haza marked a turning point in Israeli history in that Mizrahi music began to overtake the popularity of the previously dominant Ashkenazi sound, largely influenced by Russian music. By putting the music of Ofra Haza in conversation with the story of Israeli history, the author of this thesis created a cabaret using Haza's music as a storytelling device. As a creative constraint, the Kabbalistic mysticism of Hebrew letters was invoked in order to provide a non-linear element of storytelling, as each song represented a letter of the name of Ofra Haza, as it is spelled in the original Hebrew.
They Kiss: How Intimacy Directors Translate Intimate Stage Directions
Keywords: consent
intimacy
intimacy direction
intimacy director
intimate stage directions
stage directions

How does an intimacy director approach, analyse and stage an intimate stage direction? This thesis puts the pedagogy of intimacy directors and the history of stage directions into conversation with the practical application of how intimate moments are staged in Canada. By interviewing 13 intimacy directors who work in the theatre industry in Canada, a deeper understanding and common themes of how they work with dramatic text emerges. As the role of intimacy director becomes more prevalent in theatre halls across the nation and the world, it is crucial to examine the affect they have in rehearsal halls, moment to moment, as well as the larger societal impact the practice is capable of.
Validity Assessment of a 3D Depth Sensor used in Movement Tracking Games for Children with Cerebral Palsy
Keywords: Accuracy
Cerebral Palsy
Motion Capture
Movement
Sensor
Validation

In-person therapy can decrease motivation in children, and limit accessibility due to distance. Bootle Blast and Bootle Boot Camp are interactive video games that use a low-cost 3D depth sensor (Orbbec Persee+), with the goal to support conventional therapy for children with cerebral palsy. This study aims to validate the accuracy of the Orbbec Persee+ to support home-based rehabilitation games and its potential for providing correct feedback on the quality of movements. Joint data were collected from eight children and twenty adults as they participated in the games, using the Persee+ and a gold standard motion capture system for comparison. The joint coordinates and derived kinematic measurements resulted in good concurrent validity (Pearson’s r > 0.8) with good to excellent inter-rater-reliability (0.75 [0.53~0.88]) <〖ICC〗_3,1<0.99 [0.98~1.00]). The Persee+ and the rehabilitation games show potential for integration within a home-environment to provide clinicians with accurate changes in movement quality over time.
Preventing Emissions of Volatile Organic Compounds from Water Bodies Using Buoyant Photocatalysts
Keywords: Advanced Oxidation Processes
Air Quality Control
Aqueous Gas Emissions
Buoyant Photocatalysts
Oil Sands Tailings Ponds
Water Remediation

This work highlights an emerging issue in environmental engineering: mitigating gaseous emissions from water bodies. Anthropological waters like oilsands tailings ponds are responsible for large gaseous fluxes. These include volatile organic compounds (VOCs) such as methane and secondary organic aerosol (SOA) precursors. While source control is the best mitigation technique to reduce future emissions, in-situ technologies for already-emitting waters are desired. Accordingly, application of buoyant photocatalysts (BPCs) to reduce VOC emissions from oil sands tailings ponds was investigated. The passive BPC technology forms a floating layer, slowing diffusion of VOCs from water to atmosphere, while oxidizing them in water via solar power. Under 2 days of mock sunlight, 89% of SOA precursor emissions were prevented, while oxidizing 84% of aqueous parent compounds in water. This project’s success provides pathways for further research such as BPC design, modeling, long-term studies, and application to other waters.