VictorJuiz/thesis huggingface dataset:
Passive Attitude Control and Stabilization for Microsatellites

Based on the breakthroughs of Microspace missions, NewSpace ventures capitalize on radical innovation to usher in a new era where spacecraft form part of the infrastructure for global service provision in Telecommunications and Earth Observation. Confronted with a congested space domain, spacecraft developers are advised to comply with design-by-disposal practices. This thesis expands on observations of CanX-7 on-orbit behaviour, a 3U satellite developed by SFL and equipped with an innovative drag sail mechanism. A passive stabilization solution is suggested and tested to further improve upon the lessons learned from the mission’s success. Furthermore, this thesis investigates the design, testing, and validation of a passive control solution for attitude death-mode avoidance leading to power outage. The solution involves the sizing and testing of a permanent magnet to be placed on board of satellites whose mission requirements do not allow for solar panel mounting on all faces of a cubic bus geometry.

Advisor: Zee, Robert E
Expression, Purification and Signaling Profile Exploration of the Mechanosensitive Apelin Receptor

G-protein coupled receptors (GPCRs) represent the largest family of human membrane proteins. Targeted by 1/3 of approved drugs, GPCRs regulate a diverse array of signaling cascades in response to extracellular ligands. Aside from external stimuli, mechanical stimulus also modulates GPCR signaling. One example is the apelin receptor (APJR), a mechanosensitive GPCR known to mediate pathways involved in cardiac disease. In this work, we induced mechanical forces into the cell membrane through fluidity variation to determine APJR activation effects. Specifically, we focused on signaling bias differences among APJR ligands as a consequence of adjuvants designed to modify membrane viscoelastic properties. An attempt was also made to express and purify APJR in a reconstituted system in the hopes of investigating its pharmacological response in-vitro. APJR, like other GPCRs, is differentially expressed in tissues with varying membrane composition and physical properties; therefore, gaining insight in these effects is valuable in understanding receptor pharmacology.

Advisor: Prosser, Scott
Fair Licensed Spectrum Sharing between Two MNOs using Resource Optimization in Multi-cell Multi-user MIMO Networks

Spectrum sharing has been proposed to both improve spectrum utilization efficiency in modern wireless communications and provide mobile network operators (MNOs) with required spectrum at times of increased traffic. In this thesis, we investigate the use of multi-user multiple input, multiple output (MIMO) techniques to enable spectrum sharing. Specifically, we present a fair spectrum sharing system between two MNOs in multi-cell multi-user MIMO networks. We impose fairness by ensuring that each MNO receives spectrum in proportion to the amount it contributes. We formulate a constrained optimization problem to determine resource allocation and user scheduling across two MNOs. Since the problem is non-convex, we develop an effective solution through fractional programming and block coordinate descent. In addition, we incorporate channel estimation into this spectrum sharing framework in a time division duplex (TDD) system. We propose a cluster based pilot allocation mechanism where the pilot sequences are assigned to user terminals (UTs) within each newly organized cluster, which is determined by a BS-centric clustering algorithm and a modified K-means clustering algorithm. Our numerical results illustrate that the proposed spectrum sharing scheme can achieve up to a 60% improvement in terms of the average user rate among the two operators while ensuring that neither MNO is exploited for participating in the sharing mechanism, within a diagonally overlapped cell deployment. This improvement is in relation to the baseline of each MNO using multi-user MIMO communications on its own.

Advisor: Adve, Raviraj
Biasing the Average: The Role of Attention in Ensemble Processing

Ensemble processing allows the visual system to condense visual information into useful summary statistics (e.g., average size), thereby overcoming capacity limitations to visual working memory and attention. To examine the role of attention in ensemble processing, I conducted three experiments using a novel paradigm that merged the action effect (a manipulation of attention) and ensemble processing. Participants were instructed to make a simple action if the feature of a cue word corresponded to a subsequent shape. Immediately after, they were shown an ensemble display of 8 ovals of varying sizes and were asked to report either the average size of all ovals (average report task) or the size of a single oval from the set (single report task). In Experiment 1, participants were cued with a task-relevant feature (i.e., cued with size and asked to report the average or single size). In Experiments 2 and 3, participants were cued with a task-irrelevant feature (i.e., cued with colour and asked to report average size). Overall, the task-relevant cues that elicited an action biased reports of average size in the ensemble task more than the cues that were passively viewed, while task-irrelevant cues did not bias the reports of average size. The results of this study suggest that while attention is involved in ensemble processing, it only influences ensemble processing when it is directed towards a task-relevant feature.

Keywords: Action
Ensemble Perception
Perception
Vision
Visual Attention
Advisor: Cant, Jonathan
Pratt, Jay
Impact of Leucine on the Intracellular Spatial Regulation of mTORC1 in Human Skeletal Muscle

The present study used immunofluorescence methods to investigate the effect of dietary leucine on the postprandial intracellular regulation of mTORC1 trafficking and a readout of its activity in human skeletal muscle. In a crossover trial, eight recreationally active males ingested 2g of leucine or dileucine and had thigh muscle biopsies collected at rest, 30, 60 and 180 min following feeding. p-RPS6Ser240/244 was assessed across the total muscle fibre and in subcellular peripheral regions. Leucine, but not dileucine, ingestion promoted mTORC1 translocation to the cell periphery and enhanced p-RPS6Ser240/244 in peripheral (but not central) regions at 30 and 60 min. Additionally, p-RPS6Ser240/244 at 60 min was positively correlated with previously determined rates of MyoPS following leucine ingestion. The ability of leucine to activate mTORC1 in peripheral regions suggests an enhanced rate of MyoPS, as this is the intracellular space thought to be enriched in translation initiation factors, capillaries, and nutrient sensors.

Keywords: Intracellular Signaling
Leucine
mTOR
mTORC1
Nutrition
Skeletal Muscle
Advisor: Moore, Daniel R
Perceptions of Curability in Outpatients with Advanced Cancer

Objectives. (1) To identify patient characteristics associated with the perception cancer is incurable. (2) To examine whether this perception is associated with (i) patients’ goals of care (GOC) and (ii) perceptions that their family and physician are aware of their future care wishes. Methods. Medical oncology outpatients with advanced cancer completed a GOC questionnaire. Results. Previous discussion of cancer curability was associated with the perception cancer was incurable when controlling for patient age, income, and ECOG (OR=4.35, 95%CI=1.18-17.11, p=0.03). Most patients perceiving cancer was incurable reported GOC wishes of living longer (56%) over curing their cancer (7%). A total of 77% believed their family was aware of their future care wishes, but only 13% believed their physician was aware. Conclusion. Discussion of cancer curability with patients may improve their understanding of prognosis and enable GOC decision-making. Physician-patient discussions about advance care planning appear to be lacking and should be encouraged.

Keywords: advanced cancer
perception of curability
Advisor: Zimmermann, Camilla
Activating Choreographies of Care: An Inclusive Approach to 'Sidewalk Ballet'

When it comes to immersive theatre, one of its most attractive characteristics is the way it engages audiences in a fictional site by inviting them to play a role in the performance. In order to perform this role, audiences are required to adhere to particular way(s) of moving through the performance site. Similarly, when traversing the sidewalk, pedestrians must adhere to a specific set of spatial scripts established by the physical characteristics of the street, and the bodies that traverse it. This becomes exclusionary for participants from the disabled community in both fictional and non-fictional contexts, as it is primarily non-disabled pedestrians that occupy the sidewalk, and consequently shape its dominant choreographies. To address these issues, this thesis uses a research-creation approach to develop an immersive tour that explores the daily choreographies of Queen Street West, in relation to the fictional choreographies established in my performance.

Keywords: Environmental choreographies of care
Immersive theatre
Queen Street West
Accessibility
Immersive audio tour
Site-specific theatre
Advisor: Cesare Schotzko , T. Nikki
Automated Single Cell Surgery Robotic System for 2- Blastomere Embryo Applications

A fully automated single cell surgery system is proposed in this thesis. The proposed system firstuses convolutional neural network to detect the embryo location under the microscope field of view. The network produces a bounding box output which is used as region of interest for Z-stack images acquisition. The developed three-dimensional image processing algorithm uses Z-stack images to segment embryo and micropipette contours and compute their corresponding locations on the image plane. The sliding mode controller based on image based visual servoing concept uses these image plane coordinates to compute an error signal for processing. The velocity output controls the corresponding motorized stage to manipulate the micropipette to penetrate embryo membrane and reach the target location of a selected blastomere centroid. The experimental result with 2-blastomere mouse embryo has shown acceptable accuracy for certain types of cell surgery procedures and potential to extend to 4-blastomere embryo applications.

Keywords: Automation
Cell Surgery
Image Processing
Robotic Control
Advisor: Mills, James J
Wired Glass Failures: Investigation on the Mechanical Properties of Wired Glass

Despite the accidents involving wired glass, there has been no investigation on the fundamental mechanical and failure properties of this material. In this thesis, the modulus of rupture (MOR) value for wired glass was determined via four-point bend testing according to ASTM C158. The fracture surfaces of bend test samples were used to determine how the wires affected crack initiation and propagation. The final MOR value was then compared to finite element analysis (FEA) simulations of the four-point bend test to corroborate experimental results with simulation data. The MOR value for wired glass was determined to be 37 MPa ± 8 MPa, compared to FEA data which reported values of 20-50 MPa. Comparisons with reported MOR values of soda lime glass and observations of the fracture surfaces indicated that the wire mesh had no effect on the mechanical strength of the material nor on its behaviour during fracture.

Keywords: modulus of rupture
wired glass
Advisor: Perovic, Doug D
Feasibility of a Telerehabilitation Approach to Active Rehabilitation in Youth with Concussion

Active rehabilitation involving supervised exercise, education, and support promotes recovery in youth with concussion but is typically delivered in-person, which limits accessibility due to geographic, financial, and logistical barriers. The purpose of this research was to develop and explore the feasibility of a remotely delivered Tele-Active Rehabilitation (Tele-AR) intervention. A mixed-methods approach was used to explore feasibility in a pre-post case series study (n=3 youth; n=3 parents) and qualitative exploration of participant experiences in the intervention. All feasibility indicators met or approached success criteria, there were no adverse events, and all youth reported improvements in post-concussion symptoms, occupational performance, and illness perception post-intervention. Qualitative findings indicate that participants were satisfied with the intervention and appreciated the convenience and comfort of engaging from home, which facilitated youth taking responsibility for their recovery. This research provides a foundation for larger studies to evaluate efficacy of the Tele-AR intervention among youth with concussion.

Keywords: Active Rehabilitation
Concussion
Pediatric
Rehabilitation
Telerehabilitation
Advisor: Hunt, Anne
Reed, Nick
Bioaccumulation and Biomagnification of Perfluoroalkyl Substances (PFAS) in a Subarctic Ringed Seal Food Web in Lake Melville, Northern Labrador, Canada

A study was carried out on the distribution, bioaccumulation, and biomagnification of perfluoroalkyl substances (PFAS) in water and ringed seal food web of Lake Melville. The results indicate that short-chain PFAS such as perfluorobutanoic acid (PFBA) predominates in Lake Melville water. Concentrations of other PFAS are diluted by seawater intrusion from Labrador Sea along the freshwater-marine gradient of this estuary, with freshwater flowing seaward atop of seawater flowing landward. PFBA predominates in freshwater zooplankton, whereas perfluorooctane sulfonate (PFOS) predominates in marine zooplankton, and PFOS bioaccumulates in both freshwater and marine zooplankton. The results also indicate that perfluoroundecanoic acid (PFUnDA) predominates in fish livers and PFOS and perfluorononanoic acid (PFNA) predominate in ringed seal livers. Trophic magnification factor values > 1 (range from 1.66 to 7.44 log ng/ g w.w.) showed that long-chain PFCA, PFHxS, and PFOS biomagnify throughout ringed seal food web.

Advisor: Lehnherr, Igor
Vision-based Assessment of Parkinsonism Severity in Gait

Parkinsonism refers to the collection of conditions whereby the patient experiences movement symptoms similar to those common in Parkinson’s disease (PD). With respect to gait, parkinsonism may result in step and arm swing asymmetry, stooped posture, or shuffling gait; and may be influenced by dual-tasking and medication use. Because the severity of gait impairment can fluctuate on a day-to-day basis, monitoring of patients’ gait is important to allow clinicians to make informed adjustments to therapies. When paired with state-of-the-art pose-estimation algorithms, vision-based systems present an opportunity to unobtrusively monitor gait in non-clinical settings. This work evaluates how gait features and joint trajectories extracted from standard color video can be used to assess severity of parkinsonism in gait on clinical rating scales. This thesis provides insight into the algorithms and processing considerations for assessing parkinsonian gait using color video.

Keywords: Computer vision
Gait analysis
Human pose-estimation
Parkinsonism
Spatial-temporal graph convolutional networks
Advisor: Taati, Babak
A Gene-environment Interaction Model of Schizophrenia: Maternal Immune Activation in miR-137 Mutant Mice

Genome-wide association studies have implicated microRNA-137 (miR-137) as a genetic susceptibility factor for schizophrenia. Individuals with risk alleles for single nucleotide polymorphisms (SNPs) in this gene have increased symptom severity, cognitive deficits, structural and functional brain changes associated with schizophrenia. Maternal immune activation (MIA) has also been implicated as an environmental risk factor affecting neurodevelopmental disorders such as schizophrenia. Since schizophrenia is thought to result from the combination of susceptibility genotypes and environmental risk factors, we assessed the gene-environment interaction between maternal immune activation and transgenic mice that carry the miR137 rs2660304 SNP. We phenotyped the behaviour of these mice and observed an exacerbation of spatial working memory deficits in the Y-Maze by MIA in female mutant mice. No major behavioral changes were found in the open field, social interaction and prepulse inhibition assessments. Decreased performance in the Y-Maze was accompanied by exacerbation of parvalbumin-positive interneuron deficits in the dentate gyrus of female mutant mice by maternal immune activation. This thesis work demonstrated a gene-environment interaction between a miR-137 and MIA in our animal model.

Advisor: Wong, Albert HC
Preliminary Evaluation of the Double Awareness Scale in Patients with Advanced Cancer Receiving Outpatient Palliative Care

Individuals with advanced cancer are tasked with engaging in life while simultaneously planning for the end of life. The capacity to sustain this duality, termed “double awareness,” may reflect optimal psychological adaptation to advanced cancer, though limited research on this phenomenon exists. The aim of the present study was to provide a preliminary evaluation of a new measure of double awareness, the Double Awareness Scale (DAS), in 70 palliative care outpatients attending at a comprehensive cancer center in Canada. Exploratory factor analysis identified that the DAS captures the two factors central to the concept of double awareness (i.e., Life Engagement, Death Contemplation) and perhaps a third construct of Legacy Remembrance. The factors of Life Engagement and Death Contemplation met the criteria for internal consistency and construct validity, which is promising. A validated DAS may assist health care providers in monitoring patient’s ability to live meaningfully while managing advanced cancer.

Keywords: advanced cancer
death contemplation
double awareness
life engagement
palliative care
scale validation
Advisor: Rodin, Gary
Biochemical Characterization of the SLX4IP-XPF-ERCC1 Complex and its Roles in Telomere Maintenance

A subset of cancer cells use the alternative lengthening of telomeres (ALT) pathway to obtain replicative immortality. ALT is a recombination-based mechanism that requires the actions of structure-selective endonucleases, such as XPF-ERCC1 and SLX1-SLX4, to remove branched DNA intermediates called displacement loops (D-loops). Recent work suggests that the activity of these nucleases is regulated by the interaction with a non-catalytic protein called SLX4-interacting protein (SLX4IP). The goal of my project is to determine if SLX4IP modulates the nuclease activity of XPF-ERCC1 in vitro. First, I show that purified SLX4IP and XPF-ERCC1 form a complex in solution. I then show that XPF-ERCC1 cleaves the splayed arm but not the D-loop in vitro and that the addition of SLX4IP does not stimulate the cleavage of either structure by XPF-ERCC1. Further experiments are warranted to investigate the effects of additional proteins or post-translational modifications on the assembly and activity of the SLX4IP-XPF-ERCC1 complex.

Keywords: Alternative lengthening of telomeres
DNA repair
SLX4IP
Structure-selective endonucleases
Telomeres
XPF-ERCC1
Advisor: Wyatt, Haley
Muscle Oxygenation of the Paretic and Nonparetic Legs Measured During Arterial Occlusion and Exercise in Chronic Stroke

Oxygen delivery and demand are reduced in the paretic leg post-stroke, reflecting decreases of vascular function and reductions of muscle quantity and quality. It is unknown how muscle oxygenation is altered post-stroke and how it relates to functional ambulation. Skeletal muscle O2 saturation (SMO2) of the paretic and nonparetic legs of eleven post-stroke individuals were monitored with two near-infrared spectroscopy (NIRS) devices during rest, arterial occlusion, submaximal exercise and six-minute walk test (6MWT). Oxygen consumption (p=0.03) and microvascular responsiveness (p=0.04) were reduced in the paretic compared to the nonparetic leg. The exercise deoxygenation slope in the paretic leg was significantly steeper than the non-paretic leg (p=0.047) indicating a greater oxygen mismatch at the onset of exercise. Average 6MWT SMO2 of each leg was not significantly correlated with 6MWT distance. These impairments in the paretic leg may require strategies like prolonged warmups, resistance, or single leg training to improve muscle oxygenation.

Keywords: Arterial Occlusion
Exercise
Mobility
Muscle oxygen saturation
NIRS
Stroke
Advisor: Thomas, Scott
Marzolini, Susan
Optimal Control of the Erlang-R Queue: Design of Post-discharge Intervention Programs for Congested Hospital Wards

We study a control problem for the Erlang-R queue, where customers may return for additional service after initial service completion. Motivated by post-discharge Quality Improvement (QI) interventions (e.g. phone calls, outpatient follow-ups) for reducing hospital readmissions, we add the ability to reduce each departing customer’s return probability at a cost, which must be balanced against other costs incurred for customer returns and waiting time. We consider a fluid approximation of the system and characterize the optimal long-run average and bias-optimal control policies for the fluid model. Our structural results motivate intuitive surge protocols which dynamically adjust the return probability in response to congestion. Through extensive simulation experiments, we study the fluid-optimal policy’s performance for the stochastic system. In a relevant parameter regime, the fluid-optimal policy achieves long-run cost savings of 21.0% over a congestion-agnostic policy and 25.4% over an aggressive policy which applies maximum intervention whenever the queue is nonempty.

Advisor: Chan, Timothy C. Y.
Sarhangian, Vahid
Incidence of New-onset Atrial Fibrillation following Transcatheter Closure of Patent Foramen Ovale in Ontario

Patent foramen ovale (PFO) has been associated with an increased risk of cryptogenic stroke. Transcatheter closure (TC) is a commonly recommended intervention for PFO for selected patients. Some recent evidence, however, has implicated TC with increasing the risk of new-onset atrial fibrillation (AF) post-closure. This thesis represents a comprehensive evaluation of the risk of AF following PFO closure. First, a systematic review and meta-analysis synthesized current evidence in the literature for new-onset AF in PFO patients following TC. Then, a random forest classification algorithm identified which patients underwent a PFO versus an atrial septal defect (ASD) closure in Ontario administrative database records. Lastly, identified PFO patients were evaluated for incidence of new-onset AF post-closure, which was relatively low. Diabetes and being over age 60 were predictors of post-closure AF in this population. Improvements in consistency of AF monitoring are needed to gauge the true risk of AF following TC.

Keywords: administrative health data
atrial fibrillation
health services research
machine learning
patent foramen ovale
survival analysis
Advisor: Abrahamyan, Lusine
Horlick, Eric
A Hybrid Soft-sphere/IBM-VoF Model for Modelling Wet Particle Collision Dynamics

Particle collisions and interactions play a key role in many industrial applications including particulate, granulation, and agglomeration processes. The presence of moisture in these processes, in the form of liquid layers or droplets, changes the collision dynamics and the behaviour of colliding particles. In this work, we combine a soft-sphere collision model with an Immersed Boundary Method (IBM) that is coupled to a Volume of Fluid (VoF) method, for the prediction of wet particle collisions. Numerical results are validated against previous experimental and numerical work by simulating spherical particles colliding with a wet flat surface, and wet particle-particle collisions. The effect of different parameters on the characteristics of the collisions is investigated. Finally, a demonstration of particle interactions during agglomeration at a water-oil interface is presented.

Advisor: Bussmann, Markus