VictorJuiz/thesis huggingface dataset:
Ultrasound-mediated Microbubble Drug Delivery to the Injured Lung in Acute Respiratory Distress Syndrome
Keywords: Aminoglycoside
ARDS
Drug delivery
Lung
Microbubble
Ultrasound

Acute respiratory distress syndrome (ARDS) is a common diagnosis in ICUs and has a mortality rate approaching 40%. This disease is characterized by a build-up of fluid in the alveolar sacs. Most patients exhibit heterogeneous injury, with relatively normal-appearing areas abutting densely consolidated regions. This heterogeneity makes treatment difficult. Ultrasound-destruction of microbubbles (USMB) has been demonstrated to increase drug uptake by tissues but has never been attempted in the lung. We hypothesized that USMB would only increase drug uptake in edematous lung regions, since air scatters ultrasound waves. USMB increased the deposition and efficacy of low dose gentamicin in the lungs of an E. coli-induced ARDS mouse model. Further, we validated the use of USMB drug delivery to the injured lung in a porcine pneumonia model, suggesting feasibility in humans. USMB may therefore allow for targeted delivery of therapies – antibiotics, antivirals, genes – to the injured lung in ARDS.
The Role of Acculturation on Betel Nut Chewing Practices in an Urban South Asian Immigrant Population in Canada
Keywords: Acculturation
Betel nut chewing
Betel nut chewing in Canada
Betel quid
South Asian

Objectives: To determine the use of betel nut (BN) among South Asian immigrants residing in Toronto and assess association between BN chewing practices and acculturation. Methods: A cross-sectional survey was conducted with 406 participants aged 18 to 77 years old. An interviewer-administered semi-structured questionnaire was used to measure the association of BN chewing and acculturation, while also looking at participant demographics, oral health knowledge, beliefs and behaviors, and awareness. Results: Nearly half (47.8%) of the study participants chewed or had chewed BN and this was significantly associated with lower acculturation, lower oral health literacy, high exposure to Paan/Gutka and the belief that BN is not harmful. Preventive oral health behaviors were associated with decreased odds of BN chewing. Conclusions: BN use is common among immigrants who have not acculturated to Canada. Health professionals and public health program managers should be aware of the oral health consequences to provide appropriate services.
Nanoindentation Testing and Atomistic Modelling to Evaluate the Displacement Damage Threshold of Tungsten by Hydrogen Ion Irradiation
Keywords: Atomistic modelling
Ion irradiation
Nanoindentation
Radiation damage
Threshold displacement energy
Tungsten

This work exploits modern techniques to resolve the effects of the onset of radiation damage in tungsten, candidate divertor material for the ITER nuclear fusion reactor. Nanoindentation is used to study grain-to-grain variation in the near-surface effects of hydrogen ion irradiation on mechanical properties. The signature of the damage threshold is found to be the elimination of the initially elastic response to loading observed in unirradiated tungsten, which occurs as a result of deuterium ion beam irradiation at energies as low as 800 eV. Classical molecular dynamics simulations of nanoindentation complement the experimental work and suggest that postulated vacancy-type point defects resulting from irradiation can effectively lower the threshold to nucleate dislocations in tungsten. Ab initio molecular dynamics illustrates the kinetic energy transfer from hydrogen to tungsten, mediated by an intermediate mass surface impurity species, and is verified by comparison with classical approaches to predicting radiation damage.
Individual Differences in the Role of Prior Knowledge in Word Learning: An Inferred Bayesian Model
Keywords: Associative Memory
Bayesian Statistics
Learning

Individuals may gain information about the meaning of novel words by using contextual clues. A Bayesian framework of such inferential word learning suggests that learners integrate prior knowledge about possible word meanings with the statistical structure of the observed instances to make rational inductive inferences. We examined this process by creating a mechanistic Bayesian Observer model. Forty-five adults used contextual information to infer the names of twenty novel animals and tested on next-day memory. The informativeness of the contextual information was calculated from a preliminary norming study (INF rating, likelihood). INF ratings, with participants’ accuracy (posterior distribution), were used to retroactively infer participants’ prior distribution, an estimate of evidence supporting their hypotheses throughout the task. Individual’s initial prior distribution and how incrementally it was updated across the task were predictive for next-day memory. Exploratory cluster analyses suggest individuals’ strategies in the task were associated with different prior and posterior distributions.
Mechanical Design and Analysis for a Maritime Monitoring Microsatellite Mission
Keywords: design
FEA
mechanical
microsatellite
satellite
structural

There is an increasing need for monitoring and regulation of maritime vessels. This regulation can have positive environmental and economic impacts, such as improved oceanic ecosystems and fish stocks, by reducing illegal, unreported, and unregulated fishing. Historically, maritime monitoring has been achieved through ground-based observation stations, but the use of satellites has been proven as an effective method to improve on monitoring capabilities. The NorSat-3 microsatellite mission aims to demonstrate a novel approach to ship tracking with an experimental Navigation Radar Detector payload. NorSat-3 will utilize the Next-generation Earth Monitoring and Observation satellite platform, developed at the University of Toronto's Space Flight Laboratory. This thesis describes the mechanical design and analysis for NorSat-3's structural subsystem. The methodology followed to create the satellite structure is described, as well as the methods used to verify acceptable performance. Finally, the method used to test the manufactured structure is discussed.
Effects of Cannabis Abstinence on Symptoms and Cognition in Major Depressive Disorder
Keywords: Addiction
Anhedona
Cannabis
Cognition
Major Depressive Disorder
Mood Disorder

Individuals with major depressive disorder (MDD) exhibit high rates of cannabis use and research has indicated that cannabis use leads to increased risk for depression and suicidal behavior. This study sought to examine the effects of cannabis abstinence on symptoms of depression in cannabis users with MDD. Participants (n=11) underwent 28 days of cannabis abstinence. Mood symptoms were assessed weekly and cognitive symptoms bi-weekly. Abstinence was biochemically verified using weekly urine assays and participants were rewarded with a $300 contingent bonus if abstinence was confirmed. 72.7% of study completers achieved abstinence. Participants exhibited significant improvements in depressive symptoms (43.7% reduction from baseline), especially anhedonia (88.7% reduction from baseline). Improvements in visuospatial working memory performance were significant. These findings suggest ceasing cannabis use leads to reductions in depressive symptoms, and selective improvements in cognition. This research has important implications for the treatment of problematic cannabis use in individuals with MDD.
Testing the Robustness of the Perceptual Load Theory
Keywords: attentional blink
cognition
perceptual load theory
visual attention

Perceptual load theory (PLT) states that whether distractors capture attention depends on the easiness of the perceptual task. Evidence supporting PLT is almost exclusively from visual search, so it is unclear whether load effects can be found in non-visual-search tasks. To clarify this, an attentional blink (AB) paradigm was used. In Experiment 1, participants paid attention to two targets (T1 and T2), where T2 was presented after T1 at varying lags. T2’s position relative to T1 indicated perceptual load, with high load at short lags and low load at the long lag. Confirming this, an AB effect was found. To test PLT in Experiment 2, congruent or incongruent flankers were introduced beside T2. The AB effect occurred again, but no flanker effect was found. Experiment 3 made the task easier, but flanker effects were still absent. These results suggest that perceptual load effects may be most amenable to visual search.
Evaluating Longitudinal Impacts of Transit Investments on Transit Demand
Keywords: Count Regression
Logsum
Longitudinal
Transit Accessibility
Transportation Tomorrow Survey (TTS)

Land use and transportation (LUT) policies have lasting impact on the sustainability of cities. Therefore, these should be examined longitudinally to assess the long-term effects on travel behaviour. Specifically, trends of transit accessibility and transit-oriented developments are considered of the Greater Toronto Hamilton Area from 2001 to 2016. Most of the data used comes from the Transportation Tomorrow Survey and augmented by other sources. At a disaggregate level, location choice models are developed to estimate person accessibility. Generally, people living in highly-mixed areas are more sensitive to transit-walk-access wait time. Regarding the population, several regression models are developed to determine the effect of the considered transit variables on the number of household transit trips. It is found that the variables’ effects increase over time in a positive manner. These results show that these policies have consequences in the long-term and should be considered for future policy.
The Design and Empirical Evaluation of the Core-satellite Framework for Urban Passenger Data Collection
Keywords: Location Choice
MNL Model
Ride-Hailing
Travel Demand
Travel Survey
Trip Generation

Household travel surveys play a vital role in the operation and development of transportation infrastructure. The urban passenger travel data obtained through household travel surveys play a crucial role in the planning of transportation networks and form the basis of the methods used to forecast the utilization of infrastructure. Traditional household travel survey methods are growing obsolete, owing to technological trends and changing data needs. This thesis proposes a modification to the core-satellite data collection paradigm proposed by Goulias, Pendyala, Bhat (2011), that aims to take a more holistic approach to the collection of urban passenger travel data. The proposed framework presents a method for combining several purpose-specific surveys to create a basis for the analysis of travel behaviour that is greater than the sum of its parts. This thesis also presents two empirical studies that utilize the different types of data outlined in the expanded framework.
Behavioral Effects of Cannabinoids in Animal Models of Psychosis
Keywords: Cannabidiol
Dopamine
NMDA
Psychosis
Δ(9)-tetrahydrocannabinol

Psychosis is a debilitating symptom of multiple psychiatric disorders, including schizophrenia. Previous studies have demonstrated anti- and pro-psychotic properties of cannabidiol (CBD) and 9-tetrahydrocannabinol (THC), respectively, in animals and human patients. This preliminarily study investigated the behavioral effects of CBD (60 and 120 mg/kg), THC (4 mg/kg) and a 15:1 CBD+THC combination (60:4 mg/kg) in two mouse models of psychosis – GluN1KD and DATKO mice – using the open field locomotion test (OFT) and pre-pulse inhibition test (PPI). We found that in OFT, CBD had no significant effect in either model; THC significantly decreased locomotion in both models; whereas CBD+THC had seemingly opposite effects in the two models. As for PPI, no significant cannabinoid effects were seen in either model. We speculate that the discrepancies in CBD+THC effects in the two mutant models are due to differences in the increase in 2-AG levels relative to that in THC induced by CBD.
Performance and Decoding Complexity Analysis of Short Binary Codes
Keywords: Error-control coding
Polar codes
Sequential decoding
Short block length codes
Tail-biting convolutional codes (TBCC)
Ultra-reliable low-latency communication (uRLLC)

Motivated by emerging 5G wireless systems supporting ultra-reliable low-latency applications, this work studies performance-complexity trade-offs for short block length codes. While well-established tools exist for code optimization of long block length codes, there is no universal approach to the code design problem for short block lengths. Three candidate approaches for short block length designs are considered: 1) tail-biting convolutional codes decoded with the wrap-around Viterbi algorithm (WAVA), 2) polar codes decoded with successive-cancellation (SC) and an SC-list algorithm aided with error detection, 3) tail-biting convolutional codes and a class of random linear codes with a particular index profile decoded with a sequential decoding algorithm. Simulation results show that polar codes have a beneficial performance-complexity trade-off for moderate block lengths at or above 512 bits, but at shorter lengths sequentially decoded codes can have a better trade-off. WAVA decoding is competitive only at short lengths and or very low error rates.
Optimal Defibrillator Placement for In-Hospital Cardiac Arrest
Keywords: cardiac arrest
external defibrillators
facility location

In-hospital cardiac arrest (IHCA) affects over 300,000 adults across North America every year. Rapid treatment via defibrillation is an effective treatment for many IHCA victims, but the placement of in-hospital defibrillators is typically arbitrary, which may negatively impact response and patient outcomes. We conducted a descriptive analysis of IHCA incidents at St. Michael's Hospital in Toronto, Ontario, and then developed two mathematical optimization models that determined optimal placement locations for defibrillators based on historical IHCA locations such that the mean and worst-case IHCA-to-defibrillator distances were minimized respectively. We found that optimized defibrillator locations were able to significantly reduce mean IHCA-to-defibrillator distances, while worst-case distances were not significantly different compared to current placement configurations. We conducted predictive analysis on IHCA response metrics and patient outcomes but were generally unable to find any significant associations. We end with suggestions for future studies and policy implications to improve IHCA response.
Experimental Apparatus for Nanophotonic Neuroprobe-enabled Fluorescence Imaging
Keywords: Fluorescence Imaging
Functional Imaging
Integrated Optics
Light Sheet Microscopy
Neuroprobe

Fluorescence imaging has the ability to resolve brain structure and activity, in real time and with single-cell resolution. Current techniques, however, remain slow and cannot penetrate deep into the brain. This thesis investigates the use of implantable silicon photonic neuroprobes for three dimensional neuroimaging at higher framerates than what is currently possible. We present the implementation of neuroprobes as a novel method to deliver excitation in a fluorescent light sheet microscopy setup, achieving higher contrast than epi-fluorescence. We also present the algorithm and calibration of a high speed volumetric imaging setup, to monitor multiple depths simultaneously. Imaging experiments were performed on mouse brain tissues in vitro and in vivo. The system may be extended to freely moving animals in the future.
Understanding Freshwater Mussel Adhesion Through Recombinant Synthesis of Dresseina Bugensis Foot Protein 7
Keywords: bioadhesive
biomimetics
invasive species
quagga mussel
underwater adhesion

Zebra and quagga mussels (Dreissena polymorpha and Dreissena bugensis) are the most well-known invasive species in the freshwater ecosystems of North America. Both species exhibit incredible underwater adhesion but little is known regarding the adhesion proteins and mechanisms. In this thesis, the adhesive protein variants in quagga mussel, Dreissena bugensis foot protein 7 (Dbfp7) was selected based on previous MALDI and quantitative LC-MS/MS evidence. This analysis revealed a possible cleavage event undergone by all Dbfp7 variants prior to secretion onto the adhesive interface. For the first time, Dbfp7 variant 9 and variant 14 were produced recombinantly by insertion of quagga mussel Dbfp7 cDNA into an expression vector in E. coli. Dbfp7 variant 9 and 14 were expressed and purified by immobilized metal affinity chromatography at 0.3 mg/mL bacterial culture as a step towards investigating the adhesive properties of Dbfp7 for the development of novel bioinspired adhesives.
Empirical Analysis of the Relationship between Ride-hailing and Public Transit in Toronto
Keywords: Longitudinal analysis
Public transit
Relationship
Ride-hailing
Ridership
Service

The purpose of this study is to explore the nature of the relationship between ride-hailing (RH) and public transit. This thesis utilized trip-level RH data and corresponding transit ridership/operational data from Toronto for over three years (2016 to 2018). Various RH and transit service characteristics were compared over a representative sample of the RH trips. Regression models were developed to estimate the influence of RH pickup and drop-off counts on transit ridership by mode, time of day and different transit operational scenarios. The results showed that RH generally provides faster services than transit, mainly due to shorter out-of-vehicle travel time. Transit offers competitive travel times only during weekday peak commuting periods and in areas with good transit services. The modelling results showed that RH generally helps improve subway ridership while degrading surface transit ridership, especially for surface transit routes with low levels of service during commuting hours.
The Fate of Isocyanic Acid (HNCO): Investigation into Aqueous Phase Chemistry of HNCO
Keywords: Chemistry

Isocyanic acid (HNCO) is an organic acid pollutant emitted by various sources, including: biomass burning, coal combustion, vehicle exhaust from gasoline and diesel engines, cigarettes from pyrolysis of urea and oxidation of nicotine, and produced via photochemical reactions of amines and amides in the atmosphere. Because of slow gas phase losses, the predominant removal of HNCO from the atmosphere is thought to be through dry deposition and heterogeneous uptake and subsequent hydrolysis. This thesis explores the overall hydrolysis (combination of three reactions with rate constants k1, k2, and k3) of HNCO, khyd, and has re-evaluated its associated rate constants, k1 and k2, for atmospherically relevant temperatures and pH values. The Arrhenius equation for k2 was determined to be k2 = (2.4 ± 5.9) x 1010 exp(-9126 ± 695/T) s-1 but, more data was needed to confidently calculate k1. Additionally, the partitioning characteristics of HNCO in aqueous droplets were investigated through simulated evaporation events.
A Computational Model of Seizure Termination and Postictal Generalized EEG Suppression
Keywords: Computational Modeling
E/I Balance
Epilepsy
iEEG
Postictal Generalized EEG Suppression
Time-Frequency Analysis

Understanding seizure termination is clinically relevant as it is sometimes followed by the postictal generalized EEG suppression state (PGES), which is a period with suppressed activities and has been found to be associated with sudden unexpected death in epilepsy. This work aims to investigate the hypothesis that the balance of excitation and inhibition (E/I balance) in pathological brain network plays an important role in the dynamics of seizure and PGES. A network of 1000 Izhikevich model neurons was developed, and simulation results were compared with recordings from human epileptic patients. Reduced dominant frequency rise and decay rate before seizure termination and suppression in activity following termination were observed in iEEG recordings of seizures followed by PGES. Those characteristics were reproduced in the simulated local field potential by changing the E/I balance of the model network. Those results highlight the importance of E/I balance in the dynamics of seizure and PGES.
Effect of Clear Aligner Therapy on Jaw Motor Function
Keywords: Clear Aligner Therapy
Dentistry
Electromyography
EMG
Jaw Motor Function
Orthodontics

Recent evidence indicates that clear aligner therapy (CAT) induces mild to moderate tooth and jaw muscle pain. This study aimed to measure the effect of CAT on the electromyographic (EMG) activity of the masseter. It was hypothesized that CAT induces an increase in the EMG activity of the masseter during day-time. The EMG activity of the masseter was recorded in 17 adults over 4 weeks (baseline – no aligners; a passive aligner not moving teeth; first active aligner; and second active aligner) using portable devices. CAT induced a significant increase in masseter activity (all p
Textbook Outcomes in Gastric Cancer Surgery
Keywords: Gastrectomy
Population
Quality
Stomach Cancer
Surgery
Textbook

Textbook Outcomes, a composite of eight perioperative metrics, represent a comprehensive surgical quality measure in gastric cancer surgery. The objectives of this thesis were to determine the long-term survival implications of achieving Textbook Outcomes and to estimate the association between gastric cancer surgery case-volume and Textbook Outcomes. A population-based cohort study of patients with non-metastatic gastric adenocarcinoma treated with curative gastrectomy between 2004 and 2015 was conducted. Multivariable regressions analyses were conducted in order to estimate the association between (i) Textbook Outcomes and survival and (ii) gastrectomy volume and Textbook Outcomes. Textbook Outcomes were achieved in merely 23% of the cohort and were associated with a 39% reduction in mortality (aHR 0.61 [95%CI 0.50, 0.74], p
Assessing the Feasibility of High-intensity Interval Exercise in Patients with Peripheral Artery Disease
Keywords: exercise
high-intensity interval
intermittent claudication
peripheral artery disease

Peripheral artery disease (PAD) is associated with diminished functional capacity. Exercise is an effective therapy, but adherence to traditional exercise is not ideal. High-intensity interval exercise (HIIE) results in greater improvements to aerobic capacity compared to moderate-intensity continuous exercise. The objective of the study is to assess the feasibility of HIIE for patients with PAD, and explore its physiological, subjective and psychological responses. Participants performed: 1) traditional exercise (moderate-intensity walking); and 2) HIIE. Oxygen consumption, heart rate, muscle oxygen saturation and pain were assessed. Participants completed questionnaires to assess psychological responses. HIIE was feasible and safe for patients with PAD. Lower levels of pain were experienced during HIIE and all participants preferred the HIIE. HIIE may be an alternative to traditional walking and should be considered. The potential physiological and psychological advantages warrant further exploration. Reducing pain during exercise may be important to maximizing the chances for patients to succeed.