VictorJuiz/thesis huggingface dataset:
Application of the NewSpace and Microspace Philosophies to Small Satellite Constellation Development

Through improvements in terrestrial technology and reduced launch costs, small satellites have seen a steady rise in popularity. Organizations like the Space Flight Laboratory utilize the Microspace approach towards satellite development, pushing the envelope and constantly expanding small satellite capabilities. However, for large constellation missions, the NewSpace approach may offer the greater benefit, focusing on manufacturing cadence and cost reduction. This thesis aims to demonstrate how the NewSpace and Microspace philosophies can be applied to the development of small satellite constellation missions. For a new single satellite mission, mechanical modifications were made to the DEFIANT platform, which drove changes to the bus layout of components and thermal design. Qualification vibration and thermal vacuum testing was completed to certify the SPARTAN bus for a commercial constellation mission. Lastly, for a DEFIANT cluster mission, the quality assurance, assembly, and integration processes were analyzed in the context of the NewSpace and Microspace philosophies.

Keywords: constellation
Microspace
NewSpace
satellite
SFL
smallsat
Advisor: Zee, Robert E
Involvement of the Endosomal-lysosomal System in the Processing of Disease-associated Tau in Alzheimer’s Disease and Corticobasal Degeneration

The microtubule-associated protein tau pathologically aggregates in multiple neurodegenerative diseases. In neurons, tau matures from pre-aggregates into neurofibrillary tangles (NFTs) in Alzheimer’s disease (AD). In corticobasal degeneration (CBD) only dot-like intracytoplasmic aggregates of tau are seen. The endosomal-lysosomal system (ELS) has been examined in relation to Amyloid-beta processing in AD, however, there is a paucity of data on the role of the ELS in the processing of tau. Therefore, we performed a neuron-specific double-immunolabeling morphometric study to evaluate the lysosomal enzyme cathepsin D and its relation to different cellular deposits of disease-associated tau (AT8) in AD and CBD. The area density of cathepsin D immunoreactivity levels showed significant decrease in all types of tau aggregates in AD but not in CBD. AT8 and cathepsin D colocalized significantly more in CBD compared to AD. Our results indicate a differential response of the ELS to tau accumulation in AD and CBD.

Keywords: Alzheimer's disease
Cathepsin
Corticobasal degeneration
Lysosomes
Neurodegenerative disease
Tau
Advisor: Kovacs, Gabor GGK
Estimation of Chloramine Decay in Drinking Water Distribution Systems

Development of a means to identify and predict factors associated with chloramine decay in drinking water distribution systems could assist in providing targeted operational strategies which ensure regulatory compliance and ultimately lead to major cost-savings. In this study, novel bench-scale pipe section reactors (PSRs) were utilized to evaluate the impact of source water (surface or groundwater), pipe material, pipe age, and flow velocity on chloramine decay in a distribution system in the Greater Toronto Area, Ontario, Canada. Batch tests in amber glass bottles quantified decay in treated water which were compared to low- and high-flow PSR experiments to elucidate the impact of water velocity and pipe material on monochloramine decay. Of the factors examined, pipe material and condition (e.g., old or new) were identified as the most critical. Overall, the results of this study reinforce the importance of determining the source of residual disinfectant decay when considering chloramination.

Keywords: chloramine decay
drinking water
drinking water distribution
pipe section reactor
secondary disinfection
Advisor: Andrews, Robert C
Global Minimizers of the Interaction Energy and the Behaviour of Nearby Solutions to the Aggregation Equation

Over the past decade, the aggregation equation has become a popular area of research within mathematics. While much of this interest has been driven by the equation's scientific applications, the equation also raises significant mathematical questions. Notably, we associate an interaction energy to the equation, with the property that global and local minimizers of this energy correspond to steady states of the aggregation equation. In this thesis, we partially classify global energy minimizers, when working with the aggregation equation endowed with a specific class of `power-law' potentials. We then explain this partial classification, as well as its limitations. After this, we follow in the footsteps of a recent PhD thesis to query the dynamics of solutions to the aggregation equation and, in particular, the behaviour of solutions which begin `close to' a global minimizer of the interaction energy. In doing so, we outline a promising future avenue of research.

Keywords: Aggregation
Energy Methods
Optimal Transportation
Advisor: McCann, Robert J
Threat, Deprivation, and Executive Functioning in Childhood and Adolescence: A Meta-Analysis

To determine if threat and deprivation are differentially related to EF among children and adolescents, levels of EF among children exposed to adversity were compared to children not exposed. Articles from peer-reviewed journals through December 2020 were identified through multiple databases. A three-level meta-analytic model was used. Outcomes included measures indexing cognitive flexibility, inhibitory control, and working memory. Analyses were conducted on 91 articles, representing 82 unique cohorts, and 31,188 individuals. Deprivation, compared to threat, was associated with significantly lower inhibitory control and working memory. The pooled effect of deprivation on inhibitory control was g = -0.43 (-0.57, -0.29), and on working memory was g = -0.54 (-0.75, -0.33). The pooled effect of threat on inhibitory control was g = -0.27 (-0.46, -0.08) and on working memory was g = -0.28 (-0.51, -0.05). Efforts to address the effects of early-life adversity should consider differences in the type of adversity experienced.

Keywords: Adversity
Deprivation
Executive Function
Meta-Analysis
Systematic Review
Threat
Advisor: Wade, Mark
Screening for Distress the 6th Vital Sign and Health Outcomes in Patients with Cancer

Screening for distress has become a standard-of-care in oncology globally, yet evidence of its impact beyond clinical trials is limited. The aim of this thesis was to elucidate the impact of distress screening on health outcomes in a real-world oncology setting. We tested the hypothesis that distress screening improves health outcomes through two studies that examined the association between (1) suicide risk screening (SRS) and suicide outcomes; and (2) distress screening, receipt of supportive care, and cancer-related survival. We found that completion of SRS was associated with fewer suicides, but this was not attributable to SRS response. Completion of distress screening was associated with higher cancer-related survival, partially mediated by early palliative care in advanced cancer. This thesis provides real-world evidence of the association between completion of distress screening and better health outcomes in cancer, while raising new research directions about the mechanisms underlying this relationship.

Keywords: Distress
Oncology
Psychosocial
Screening
Suicide
Advisor: Li, Madeline
Improving the Magnetic Resonance Characterization of Cardiac Infarct Heterogeneity with Non-Cartesian Gradients

Sudden cardiac death is among the global leading causes of death and is most often caused by ventricular tachycardia where areas of heterogeneous infarct can decouple the cardiac cycle from its natural rhythm. Treatment for ventricular tachycardia can involve catheter ablation procedures which may be made more effective by obtaining high resolution scar maps via cardiac MRI. Currently, Cartesian imaging is the standard for cardiac MRI but the resolution and coverage obtainable using Cartesian techniques is limited by long acquisition times. This thesis addresses the use of non-Cartesian k-space trajectories which reduce scan times while increasing coverage and resolution. First, the efficiency benefits of non-Cartesian sequences are explored. Then, non-Cartesian images are presented and the image quality is validated against standard Cartesian images. The thesis ends with a discussion of how non-Cartesian trajectories can be further applied in different ways to improve the state of cardiac scar mapping with MRI.

Keywords: 3D cones MRI
Cardiac MRI
CMR
Non-Cartesian
Stack of spirals
Ventricular Tachycardia
Advisor: Wright, Graham A
EEG Biomarkers of Reduced Inhibition in Microcircuit Models in Depression

Reduced cortical inhibition by somatostatin-expressing (SST) interneurons has been strongly associated with treatment-resistant depression. However, whether the effects of reduced SST inhibition on microcircuit activity have signatures detectible in electroencephalography (EEG) signals remains unknown. We simulated resting-state activity and EEG using detailed models of human cortical layer 2/3 microcircuits with normal (healthy) or reduced SST inhibition (depression). Healthy microcircuit models showed emergent key features of resting-state EEG, and depression microcircuits exhibited increased theta, alpha and low beta power (4 – 15 Hz). The changes in depression involved a combination of an aperiodic broadband, and periodic theta and low beta components. In both conditions, neuronal spiking showed a spike preference for the phase preceding the EEG trough. Our study thus links SST inhibition level to features in EEG simulated from detailed human microcircuits, which can serve to better identify mechanistic subtypes of depression using EEG, and non-invasively monitor modulation of cortical inhibition.

Keywords: Biomarkers
Depression
EEG
Inhibition
Microcircuits
Advisor: Hay, Etay
Griffiths, John D
Rhythmic Sampling Supports Episodic Memory Formation

Theta oscillations (3-9 Hz) in the hippocampus have been posited to mitigate the trade-offs between encoding and retrieval by segregating them in time (i.e. at opposite phases). However, there is limited behavioral evidence that humans cognitively cycle in and out of encoding and retrieval states at this rhythm. Here, I adapted the behavioral oscillation paradigm to investigate if episodic memory formation is rhythmic. In the present experiment (n=79) I found that associative retrieval performance oscillated at the theta frequency (5-6 Hz) with respect to a cue-image delay during the time of encoding. This same rhythmicity was not found for an attention task performed during the time of encoding, suggesting rhythmicity in memory formation was found over and above rhythmicity in perceptual processing. These data provide the first evidence demonstrating that human memory formation oscillates at a similar frequency as neural oscillations in the hippocampus known to underlie memory formation.

Keywords: Encoding
Memory
Oscillations
Advisor: Duncan, Katherine
Factors Associated with Surgical re-Replacement or Transcatheter Pulmonary Valve Insertion of the Second Pulmonary Conduit

Patients receiving a right ventricle-to-pulmonary artery conduit (PC) in infancy will require successive procedures or replacements, each with variable longevity. We sought to identify factors associated with time-related risk of a subsequent surgical replacement (PC3) or transcatheter pulmonary valve insertion (TPVI) after a second surgically-placed PC (PC2). From 2002 to 2016, 630 patients were enrolled after initial valved PC insertion at age

Keywords: congenital heart disease
congenital heart surgery
pulmonary conduit
pulmonary valve
Advisor: McCrindle, Brian W
Barron, David J
“In the lion’s den, we just want to know”: A Qualitative Exploration of Parents’ Decisions to Pursue Pediatric Whole Genome Sequencing

This dissertation aimed to explore how personal, interpersonal, and societal factors influence parents’ decision to pursue whole-genome sequencing (WGS) for their child. Semi-structured interviews were conducted with parents of children with heart conditions who were offered WGS and secondary variants. Transcripts were coded inductively and deductively, using the Social Ecological Model and Kohler’s framework of personal utility. Nineteen participants were interviewed. During decision-making, parents described personal value they expected to gain from WGS. Gaining an understanding of their child’s current and future health was beneficial and acted as a precursor to enabling cognitive, emotional, and behavioural control. However, parents’ enhanced sense of control required a readiness to learn genetic information. Social contexts also impacted parents’ decisions; WGS was valued as a mechanism for mitigating blame and legitimizing disability. Findings shed light on the acceptability of WGS and may inform counselling strategies and health technology assessment.

Keywords: Genomic sequencing
Parent experience
Qualitative methods
Secondary findings
Advisor: Hayeems, Robin
Examination of Infection Dynamics within a Viral Consortium Infecting the Haptophyte Alga Chrysochromulina parva

Viruses are ubiquitous in freshwater and are crucial for nutrient cycling in all aquatic systems. However, little is known about the interactions of freshwater algal viruses and their hosts, or the ecological dynamics of complex systems with multiple pathogens. Here, I investigated these dynamics in a consortium of viruses and virophages infecting Chrysochromulina parva, a freshwater haptophyte alga. Cultures of C. parva were grown and subjected to sequential rounds of lysis. Community composition was assessed using quantitative PCR assays specifically targeting each virus. Viral titre was determined by Most Probable Number assays. All known lytic agents were outcompeted within four rounds by another, unknown, lytic agent or agents. This study provides the first data on inter-virus competition for any viruses of aquatic primary producers, allowing us to generate further hypotheses about the complex ecology of algal viruses, and the coexistence of multiple viruses parasitizing the same host.

Keywords: algae
competition
ecology
freshwater
microbiology
viruses
Advisor: Short, Steven M
Visualizing Insider USB File Exfiltration Anomalies: A Financial Services Case Study

Data exfiltration by insiders (or people masquerading as insiders) is a major threat for organizations that store and use highly confidential data. Standard cybersecurity methods using firewalls and perimeter strengthening measures fail against insiders, and machine learning methods for anomaly detection generate large numbers of false alarms. I worked with domain experts in a large Canadian financial services company and developed new security visualization technology through a Participatory Design (PD) approach. The resulting File Activity Real-Time Investigation Dashboard Application (FARIDA) is usable for a range of stakeholders, allowing experts to quickly review large amounts of data and enabling non-technical investigators to participate in early stages of the anomaly detection process. This research is a first step towards more general use of visualization tools to monitor sensitive data, and demonstrates how human factors approaches can beneficially supplement the development of AI methods in cybersecurity, using data exfiltration as an example.

Keywords: File Activity Monitoring
Insider Security Monitoring
Interactive Dashboard
Participatory Design
Security Visualization
User Research
Advisor: Chignell, Mark
Use of Machine Learning Classifiers based on Visual Metrics in Children with Acquired Demyelinating Syndromes

Multiple Sclerosis (MS), an inflammatory degenerative disease and the visual pathway is a key target in the search for a reliable and easily obtainable diagnostic biomarker that can aid the diagnosis. The objective of this study was to investigate the utility of machine learning (ML) based on optical coherence tomography (OCT) features to identify children with MS and other ADS. In this cross-sectional study a total of 512 eyes from 69 (neyes = 138) healthy controls and 187 (neyes = 374) children with ADS were included. Random forest classifier with recursive feature elimination identified MS with 80% accuracy. A set of eight retinal features were identified as the most important in this classification. In conclusion, this study demonstrated that ML classifiers can be used to diagnose MS in children based on structural OCT measures alone with high accuracy, sensitivity and specificity.

Keywords: Machine learning
Multiple sclerosis
Optical coherence tomography
Pediatric
Advisor: Yeh, E. Ann
Computational Analysis of Druggability and Genetic Variability of SARS-CoV-2 Pocketome

Emerging novel coronaviruses (CoVs) and new variants of SARS-CoV-2 are a major public health threat. One therapeutic strategy to face this challenge is to develop broad-spectrum CoV inhibitors, also known as pan-CoV drugs by targeting a druggable and conserved binding site of CoV proteins. Therefore, we performed a systemic analysis of seventeen SARS-CoV-2 protein structures and mapped their binding sites in a quest to determine the most conserved druggable sites. We then analyzed the variation of residues lining the SARS-CoV-2 drug-binding pockets across 27 α- and β-CoVs and across thousands of SARS-CoV-2 samples from COVID-19 patients. Our findings indicate that the most promising targets for developing pan-CoV drugs include the catalytic site of non-structural protein 12 (nsp12; RNA-dependent RNA polymerase) and the RNA central channel of non-structural protein 13 (nsp13 helicase). Lastly, we present our data on an interactive web portal (https://www.thesgc.org/SARSCoV2_pocketome/) to allow users to view the individual proteins.

Keywords: Amino acid conservation
Coronavirus
Druggability
SARS-CoV-2
Structural bioinformatics
Structural biology
Advisor: Schapira, Matthieu MS
Hybrid Nanometal Morphing Structures

The demand for increasing the efficiency of aircraft has led to the pursuit of improved and novel structures. Hybrid structures with morphing capabilities aim to address this through the use of materials with high specific strength, improved manufacturing techniques, and the ability to change shape during flight. A quadrotor propeller was chosen as a proof of concept design for a morphing hybrid structure. This thesis investigates the implementation of morphing via mechanical actuation into various propeller designs, weighing the benefits and tradeoffs for each. A NACA 2412 airfoil was optimized for two separate flight conditions, and various designs were conceptualized for implementation. A design was selected for a finite element analysis to determine the viability of morphing within the structure.

Keywords: Hybrid structures
Morphing
Propeller
Structural design
Advisor: Steeves, Craig
Reversing CRDTs Through Compensating Operations

Conflict-free replicated data types (CRDTs) are popular choices for implementing eventual consistency in distributed systems that prioritize high availability. However, reversibility is largely unexplored in CRDTs, despite its potential use in microservices, collaborative editing software and distributed databases.  In this thesis, reversing CRDTs is defined as compensating for the effect of reversed updates. Reversible operations are extensions to existing CRDTs' interfaces that reverse previous updates. Two different approaches and algorithms to achieve reversibility are discussed and developed.  A distributed key-value database called rKVCRDT is implemented for proof-of-concept with the support of reversible CRDTs (rCRDTs). The performance characteristics of rCRDTs are evaluated using rKVCRDT. The evaluations show that although adding reversibility does have an impact, the overall performance is still dependent on multiple factors and varies among different CRDTs. Finally, two optimization methods for rCRDTs are proposed to improve the performance.

Advisor: Jacobsen, Hans-Arno
Evaluation of an Electroencephalography Source Imaging based Brain-computer Interface for Youth with Brain Lesions

Brain lesions are the underlying cause of many neurological disorders that lead to physical impairments and disabilities. Brain-computer interfaces (BCIs) have been proposed as an access technology for these individuals since they allow users to communicate using only their brain activity. While electroencephalography (EEG) is one of the most popular BCI modalities due to its affordability and non-invasive approach, it suffers from low spatial resolution and does not account for unique anatomical features present in BCI users with brain lesions, resulting in suboptimal decoding accuracies. This thesis evaluated the classification performance of an EEG source imaging (ESI)-BCI system that incorporates anatomical information from magnetic resonance imaging (MRI) to estimate electrical activity in the brain based on measured scalp potentials. We investigated the offline classification performance of an ESI BCI and EEG BCI in decoding left- versus right-hand motor execution and motor imagery tasks in 9 youth with brain lesions (cerebral palsy and brain injury). Generally, the classification accuracy of the ESI BCI was comparable to that of an EEG BCI. The ESI BCI showed an 8.68±7.84% improvement in one participant for the motor execution task (p

Keywords: brain-computer interface
EEG source imaging
movement decoding
Advisor: Chau, Tom TC
Development of a Novel Computer-aided Design Experiment Protocol for Studying Designer Behaviours

Computer-Aided Design (CAD) is indispensable for modern engineering endeavors. The craft of creating CAD models requires extensive experience and expertise. Unfortunately, most traditional CAD training remains focused on declarative knowledge and not higher-level thinking. Studying expert usage could provide insights into the elements of effective CAD modelling. As the first step towards decoding CAD expertise, a novel experimental protocol was developed to capture and characterize designer actions during modeling. The study will serve as a foundation for future CAD design research. The protocol was tested with an experiment of 19 participants of varying skill levels. Event plot visualizations and hidden Markov Models revealed differences between two groups of performance-segmented participants, with the experts adopting a more consistent and organized modelling approach. Compared to existing methodologies, the automated processes developed for this study leverages automatic data collection and analysis to significantly reduce the time and effort required toperform design experiments

Keywords: CAD
Computer-Aided Design
Design Research
Designer Behavior
Advisor: Olechowski, Alison
Experimental-numerical Determination of the Lorentz and Magnetostriction Mechanism in the Periodic Permanent Magnet Electromagnetic Acoustic Transducer on Steel

This thesis determines the relative strength of magnetostriction to Lorentz within the Periodic Permanent Magnet Electromagnetic Acoustic Transducer (PPM EMAT) on steel, which is designed to induce only the Lorentz mechanism. As both mechanisms operate at the same frequency and wavelength, the ratio between Lorentz and magnetostriction is determined through an experimental-numerical method. Another EMAT, which only induces magnetostriction, is constructed to operate at the same wavelength and frequency. In addition, it replicates the magnetic conditions underneath the PPM EMAT that cause magnetostriction. A series of experiments are conducted with both EMATs in a pitch-catch configuration, finding that magnetostriction is significant only at the transmitter. A magnetostriction model is developed specifically for the PPM EMAT, and 3D Finite Element simulations predict EMAT performance. It is found that magnetostriction reduces the output of the PPM EMAT transmitter output by an average of 29% across multiple input current tests.

Keywords: EMAT
Lorentz
Magnetostriction
Nondestructive Testing
Ultrasound
Advisor: Filleter, Tobin
Sinclair, Anthony