VictorJuiz/thesis huggingface dataset:
Applications of Clinical Engineering and Interaction Design to the Neurovascular Clinic
Keywords: Clinical Engineering
Computational Fluid Dynamics
Human Computer Interactions
Human Factors
Neurovascular
User Interface Design

Novel computational tools often face difficulty in clinical adoption due to lack of clinical user involvement in the design process. While there is extensive research in Computational Fluid Dynamic (CFD) modeling of the vascular system, there remain challenges in translating this knowledge into the clinical domain for data-driven treatment decisions. To facilitate the clinical adoption of CFD technology, a co-design-centered approach was used to involve practitioners in the design of user interfaces for several clinical challenges: a custom interface was prototyped for medical image segmentation; interactive flow visualization interfaces were tested by clinical practitioners and fluid researchers; and a methodology was developed for recording, visualizing, and categorizing pulsatile tinnitus sounds. Based on work conducted in this thesis, recommendations are provided for implementing multi-sensory design theories (audio, visual and tactile) in design and engineering education and their implications for improving the design of clinical diagnostic tools.
Methodology and Equipment Improvements to Radiation Test Campaigns and Electrical Developments for Microsatellites
Keywords: Proton Beam
Radiation
Radiation Effects

Satellites operating near earth are subject to less radiation than deep space. This has allowed the use of commercial off the shelf electronic components for small satellites operating in low-earth orbit. Even though radiation levels in low-earth orbit are far lower than deep space, there is significantly more radiation than on the surface of the planet. Commercial off the shelf electronic components must therefore be screened and tested to ensure proper operation on orbit. This thesis begins by giving an overview of the Modular Power System, which controls and regulates power aboard Space Flight Laboratory satellites. It then delves into the process, the findings, and the improvements made to the radiation test methodology at the Space Flight Laboratory. The knowledge gained during a radiation test campaign allowed for better test equipment and procedures to be envisioned. This lead to the design of two pieces of test equipment which could more accurately quantify radiation effects. Finally, the redesign of a switch-mode power supply to fit into a satellite is summarized. These works are presented in part as a chronological overview of the works performed during the 2021-2023 Master’s Program.
Behavioural Isolation between Populations that Evolved in Different Larval and Mating Environments
Keywords: Behavioural isolation
Drosophila
Ecological speciation
Experimental evolution
Mating environment
Speciation

Behavioural isolation (BI) is often the beginning of speciation. BI is the result of evolved differences in response to the mating environment (ME). MEs may mediate if BI evolves for two reasons. Ecological speciation occurs because of different traits being favoured in alternative environments. Alternatively, MEs vary in the selective constraint they impose such that populations evolving in a ‘constraining’ ME would be less likely to evolve BI. In this case, the ME is not the direct cause of BI but permits its evolution via other drivers. We test these ideas with 28 populations, evolved under one of two MEs and one of two larval environments. BI is not maximal between populations evolved in different MEs. Rather, BI is stronger among populations from one ME. This ME promotes BI, but it does not drive it; BI occurs if they evolved in different larval environments, indicating a role for ecological speciation.
Hormonal and Inflammatory Features of Heart Failure with Preserved Ejection Fraction
Keywords: Heart failure
Inflammation
Menopause

Heart failure with preserved ejection fraction (HFpEF) is a common form of heart failure with few therapies and grievous outcomes. The importance of sex hormones and specific inflammatory drivers are yet to be understood within the condition. This thesis presents results addressing these gaps. Under one study, the influence of menopause, a feature common amongst HFpEF patients, was examined using a mouse model leveraging chemically accelerated ovarian failure (AOF). Despite the loss of cardio-protective ovarian function, AOF did not worsen HFpEF phenotype severity. The presence of infiltrating immune cells within the heart was however elevated due to AOF. A separate investigation applied systems biology to public cardiac gene expression data derived from HFpEF patients. This uncovered evidence for inflammation driven by interferon regulatory factor 3 (IRF3) as consequence of obesity. These two lines of work provide direction for further studies examining both the presentation and molecular underpinnings of HFpEF.
Single-Nucleus Profiling Identifies Accelerated Oligodendrocyte Precursor Cell Senescence in a Mouse Model of Down Syndrome
Keywords: Down syndrome
Genetics
Molecular biology
Neurosciences
Oligodendrocyte precursor cells
Single-cell genomics

Down Syndrome (DS) is the most common genetic cause of intellectual disability (ID) worldwide and is associated with lifelong cognitive deficits. However, the precise mechanisms driving neurologic impairment and neuroinflammation in DS are poorly understood. Using the Ts65Dn mouse model of DS, I performed an integrated single-nucleus ATAC-seq and RNA-seq analysis of the mature adult cortex. I identified cell type-specific mRNA and chromatin-associated changes in the Ts65Dn cortex, including regulators of transcription, translation, myelination, and inflammation. I discovered enrichment of a senescence-associated transcriptional signature in trisomic oligodendrocyte precursor cells (OPCs), epigenetic changes consistent with a loss of heterochromatin, and a senescence phenotype characterized by the upregulation of senescence-associated-β-galactosidase (SA-β-gal) activity, loss of LaminB1 (LMNB1), and reduced proliferation. Treatment of Ts65Dn mice with the senescence-reducing flavonoid, fisetin, rescued cortical OPC senescence activity and restored the number of OPCs. Together, these findings suggest that cortical OPC senescence may be an important driver of accelerated aging and neuroinflammation in DS.
Uncovering General and Specific Relationships Between Psychopathology and Neurocognition: A Hierarchical, Dimensional Approach Using Latent Variable Models
Keywords: cognition
dimensional psychopathology
hierarchical taxonomy of psychopathology
neuropsychology
transdiagnostic

Discriminable relationships between psychiatric disorders and neurocognition have not been strongly established despite evidence of associations between the two. This may be due to prevailing psychiatric classification systems that define psychiatric disorders as discrete entities, contrasting with alternative empirically based approaches of hierarchical dimensional structures which may better elucidate broader and narrower relationships between psychopathology and neurocognition. In this remote study, 1000 adults with mental health concerns completed a dimensional and hierarchical measure of psychopathology and a comprehensive neurocognitive battery. A six-factor bifactor model of psychopathology and a three-factor bifactor model of neurocognition were supported by both theory and standard fit indices. Hierarchical regressions based on estimated factor scores suggested significant negative association of general psychopathology with general neurocognition, and detachment with general neurocognition and social cognition. A positive association was found between anxiety and social cognition. These preliminary findings suggest associations between psychopathology and neurocognition are largely non-specific.
Exploring the Conversations of a Motivational Interviewing Chatbot: A Topic Modeling Approach
Keywords: Chatbot
Motivational Interviewing
Natural Language Processing
Topic Modeling
Transformers

The advent of large language models, such as BERT, GPT-3, and ChatGPT has galvanized research in chatbots, particularly in the context of addiction therapy. One such chatbot is MIBOT, developed through active collaboration between researchers at the University of Toronto and MI clinicians at the Centre for Addiction and Mental Health (CAMH). The goal of the MIBOT project is to develop a chatbot to emulate the principles of Motivational Interviewing in the context of smoking cessation therapy. While chatbots provide benefits in reaching underserved populations, there is a challenge in reviewing conversation transcripts due to the large number of conversations they may have. To address this challenge, topic modeling methods are analyzed in their ability to review transcripts. We find that topic modeling approaches help researchers (1) explore and summarize the MIBOT transcripts; (2) plan appropriate responses in an M-Iinspired conversation; and (3) stimulate further research and question generation.
Meta-Learning-Based Fronthaul Compression for Cloud Radio Access Networks
Keywords: cloud radio access networks
deep learning
fronthaul compression
meta-learning
transform coding

This thesis investigates the fronthaul compression problem in a cloud radio access network, where a transform-compress-forward scheme consisting of well-designed transformation matrices and uniform quantizers is proposed to satisfy the fronthaul capacity constraint. To reduce the communication overhead for designing the transformation matrices, this thesis further proposes a deep learning framework to first learn a suboptimal transformation matrix at each remote radio head (RRH) based on the local channel state information (CSI), and then to refine it iteratively. To facilitate the refinement process, we propose an efficient signaling scheme that only requires the transmission of low-dimensional effective CSI and its gradient between the central processor and RRH, and further, a meta-learning based gated recurrent unit network to reduce the signaling transmission rounds. Simulation results under three applications show that the proposed two-stage neural network can perform close to the fully cooperative global CSI based benchmark with significantly reduced communication overhead.
Athletes’ Experiences of Addressing Maltreatment Through a Reporting Process: A Critical Narrative Analysis as Guided by Trauma-Informed Practice
Keywords: Abuse
Healing
Justice
Maltreatment
Sport
Trauma

A critical narrative approach guided by trauma-informed practice explores athletes’ experiences of addressing maltreatment through a formal reporting process. Safe Sport initiatives often marginalize the knowledge and needs of athletes, particularity those from equity-denied groups. This study aims to amplify the voices and experiences of athletes who have been harmed within what I interpreted as oppressive institutions and structures. An overview of maltreatment in sport within a Canadian context and an autoethnography on the importance and challenges of implementing a research project as a (developing) trauma-informed practice are offered. The results are presented as idiographic narratives on four athletes’ experiences of the reporting process, which illuminate the harm and re-traumatization perpetuated within reporting processes. The trauma-informed practice within this study offers an alternative modality of engaging with athletes who have experienced harm; one that prioritizes the on-going consent, autonomy, and well-being of the athletes with a commitment to harm reduction.
Neuroimaging of Brain Iron in Schizophrenia
Keywords: Neuroimaging
Schizophrenia
Suicide

Schizophrenia is an often severe and chronic psychotic disorder. Although many disease mechanisms have been explored, the biological basis of schizophrenia remains elusive. Additionally, the elevated lifetime risk of suicide in schizophrenia implies there may be an unknown pathophysiology underlying the two. Our objective is to explore the correlation of brain iron, which is known to modulate dopamine synthesis, in schizophrenia and suicide. For samples of schizophrenia subjects and healthy controls, as well as individuals with schizophrenia at high and low risk for suicide, brain iron levels in the substantia nigra were investigated using quantitative susceptibility mapping. Although there were no differences in brain regional iron levels, volumes of the substantia nigra may be reduced in patients with SCZ and further reduced for those at high risk for suicide. The present study encourages further research on iron levels and deep grey matter nuclei in the pathophysiology of schizophrenia and suicide.
Using Accelerated Testing to Indicate Later-Age Chloride Ingress and Bulk Resistivity of Concrete
Keywords: Concrete
Durability
Permeability
RCPT
Resistivity
SCMs

Supplementary Cementitious Materials (SCMs) are used in concrete to help improve the durability of the hardened concrete and to reduce global warming potential. Ambient curing does not provide enough time for the SCMs to develop their potential by 28 days, as they typically require 91 days, as allowed in CSA A23.1. Use of optional accelerated curing allows for SCMs to develop more of their potential by 28 days and speed up evaluation for construction acceptance. This study aims to promote the use of accelerated curing for evaluation of SCM concretes in terms of strength, Rapid Chloride Permeability Test (RCPT), and Bulk Electrical Resistivity Test data. These tests were conducted on both cylinders and cores extracted from slabs on concrete mixtures with varying levels of SCMs. The results were then compared to determine if accelerated curing test data can be used for acceptance. The correlation between cylinder and core results are discussed, as well as the correlation between the RCP and bulk resistivity test data. The results show that accelerated curing provides similar or lower permeability results.
Emergency Dental Care in a Paediatric Hospital during COVID-19
Keywords: COVID-19
DENTAL CARE
DENTAL EMERGENCIES
PEDIATRIC DENTISTRY

PURPOSE: To investigate the impact of the COVID-19 pandemic on patient demographics, presenting dental conditions, and treatment provided in the Emergency Department (ED) at The Hospital for Sick Children (SickKids) in Toronto, Ontario. METHODS: A retrospective chart review of dental-related ED complaints during the pandemic period (March 16, 2020 to March 15, 2021) were reviewed and compared to pre-pandemic period (June 2, 2018 and March 15, 2020). Demographic and clinical data were collected. RESULTS: There was a significant increase in patients of lower socioeconomic status (SES) presenting to the ED during the pandemic (p=0.019). The prescription of oral anti-infectives (p=<0.0001) and dental extractions (p=0.0006) increased significantly during the pandemic compared to the control period. CONCLUSIONS: Patients presenting to the ED during the pandemic were of lower SES, further highlighting pre-existing oral health disparities in Canada. Restrictions during the pandemic contributed to increased emergency management with oral anti-infectives and dental extractions.
Understanding Ventilator-Induced Lung Injury: The Role of Mechanical Power
Keywords: acute hypoxic respiratory failure
intensive care medicine
invasive mechanical ventilation
mechanical power
threshold analysis
ventilator-induced lung injury

OBJECTIVES: To assess the association between high (> 17 J/min) dynamic mechanical power (dynMP) within the first 24 hours of invasive mechanical ventilation (IMV) and ICU mortality, and determine a critical threshold of dynMP affecting mortality rates. METHODS: Adult patients with acute hypoxemic respiratory failure requiring IMV were included. Propensity score weighting and logistic regression models were used, and a change-point regression model was applied. Secondary outcomes included duration of mechanical ventilation and ventilator-free days. RESULTS: Analysis involved 9,135 patients. High dynMP was associated with increased ICU mortality. The relationship was non-linear, with a steep incline at low dynMP levels. No single and reproducible dynMP threshold was identified. High dynMP reduced extubation rates and ventilator-free days. CONCLUSIONS: High dynMP within the first 24 hours of IMV was independently associated with increased ICU mortality. Reducing dynMP at initiation of IMV may be a promising strategy to reduce mortality.
Investigating the Orthotic and Acute Therapeutic Effects of a Novel Upright Balance Therapy for Individuals with iSCI and Developing a New Clinical Version
Keywords: Functional Electrical Stimulation
Quiet Standing
Rehabilitation
Visual Feedback Training

Individuals with incomplete spinal cord injury (iSCI) experience an increased rate of falls due to decreased sensorimotor function. We demonstrated in a prior longitudinal pilot study that a therapeutic system using functional electrical stimulation and visual feedback balance training (FES+VFBT), produced therapeutic effects in individuals with iSCI. However, the exact role and mechanism FES in the system is not understood. Additionally, hardware and software limitations make clinical application of the system difficult. In this thesis, I determined the orthotic and acute therapeutic effect of FES in the FES+VFBT system and developed a new clinical version of the system. The FES demonstrated an orthotic effect by increasing ankle stiffness and an acute therapeutic effect by increasing corticospinal excitability. A new clinical version of the system was successfully recreated using the Wii Balance Board and Unity game engine and was proven to perform at least on par with the lab-based system.
Design of Multi-component Alloy Catalysts Aided by Density Functional Theory and Machine Learning
Keywords: Alloys
Catalysis
Data Science
Density Function Theory
Machine Learning

Catalysts are a key pillar in countless industrial processes and represent key components to some of the worlds most important solutions regarding climate change. As a result, increasingly complex systems such as Binary and High Entropy Alloys are being studied to improve performance. For these systems, the large configurational spaces require high throughput techniques such as machine learning to properly study but current methods are not perfect. This thesis presents four advancements in scientific insight and methodologies to accelerate computational catalyst design. Firstly, a bottom up approach utilizing simpler catalysts systems to design increasingly complex electrocatalysts is presented. Secondly, a novel Machine Learning technique is proposed to elucidate mechanistic insight for these increasingly complex alloy systems. Thirdly, a techno-economic pipeline is designed to optimize the alloy electrocatalysts. Lastly, an improved graph representation technique is presented that allows for more universal ML frameworks with improved catalyst discovery capabilities.
A Mesoscopic Central Limit Theorem for Sample Covariance Matrices and their Linearization
Keywords: Central Limit Theorem
Random Matrix Theory
Sample Covariance Matrix

We consider sample covariance matrices of the form $X^TX,$ where $X$ is an $M\times N$ random matrix with independent entries. We prove a central limit theorem for random variables of the form $\tr f(X^TX)$ where $f$ is taken to be a smoothed out indicator function. In order to establish this result, we first prove an analogous result for the linearized matrix, $\big(\begin{smallmatrix} 0 & X^T \\ X & 0 \\ \end{smallmatrix}\big)$.
A Micro Flow Reactor for Studying Pollutant Formation
Keywords: Combustion
Extinction
GCMS
Micro flow reactor
Pollutants
Soot formation

Soot formation from combustion of hydrocarbons is a key contributor to the environmental impact of energy use. Conventional research burners for combustion studies provide great insight into flame sooting behaviour, but are not able to discern the early phases of pollutant formation due to the interdependence of the flow fields and flame conditions. Micro flow reactors isolate the flow field effects and present a controlled chemical and physical environment, thus being ideally suited to study pollutant formation at flame conditions in a tractable setting. In this thesis the design and evaluation of a novel micro flow reactor is presented. This reactor is operable with liquid fuels up to 1350 K, and provides optical and physical access for a variety of diagnostics. Implemented diagnostics include soot measurement by gravimetric and optical methods, and gas composition analysis through gas-chromatography--mass-spectrometry. The reactor was evaluated using 4 liquid hydrocarbon fuels in the C_7 range with different chemical features. This was done under near flame conditions, and the expected behaviour from these evaluation fuels was observed, showing a high sensitivity in studying polycyclic-aromatic-hydrocarbon and soot formation processes. The micro flow reactor is found to be a promising tool for future pollutant formation studies.
Early Life Sleep Loss Impacts Sociality in Drosophila melanogaster
Keywords: ageing
Drosophila melanogaster
sleep
social network analysis
social networks

Decades of behavior genetics research offer the consensus that fruit flies demonstrate sleep and social behaviors. Though the effects of early-life sleep deprivation on dyadic social interactions in Drosophila melanogaster have been characterized, little is known about its effects on their group behavior. In this study, we used social network analysis (SNA) to characterize the impacts of early-life sleep deprivation on network interactions of adult Canton-S strain D. melanogaster. Through our bivariate experimental design, we sleep deprived flies at two different ages (newly eclosed and 6-d old) and acquired their network behaviors at three different age conditions (7-days, 12-days, and 17-days old) alongside age-matched non- sleep deprived controls. We found statistical differences between sleep deprived and control groups in younger, but not older, networks across various interaction measures, which encourages further investigation into the early life neurogenetic sleep correlates that regulate the development of the social brain and behavior.
Investigating Non-invasive Saphenous Nerve Activity by various Electrode Configuration Recordings at the Ankle during Non-invasive Saphenous Nerve Stimulation
Keywords: Compound nerve action potentials
Neuromodulation
Non-invasive stimulation
Overactive Bladder
Saphenous nerve
Tetrapolar electrode configuration

Saphenous nerve stimulation is an emerging therapy that can potentially be used as a treatment in patients with overactive bladder (OAB). One of the challenges is the inability to determine whether the nerve is electrically activated. This thesis investigated the feasibility of non-invasively recording neural activity evoked by saphenous nerve stimulation. In 16 human subjects, four different recording electrode configurations (monopolar, bipolar, tripolar, and tetrapolar) were used to measure compound nerve action potentials (CNAP) and subsequently compare the peak-to-peak amplitude of the neural signal (Vpp) produced by recording electrodes. The tetrapolar recording configurations yielded the largest Vpp that was at least twice that of the other configurations. This configuration also enabled CNAP detection at lower stimulation amplitudes compared to monopolar configurations overall and one bipolar configuration (Bi4-5). This non-invasive recording technique provides the first-in-human data that shows the feasibility of using a tetrapolar recording configuration for measuring saphenous nerve signals in humans. Further clinical study is required to assess feasibility in OAB patients.