VictorJuiz/thesis huggingface dataset:
Nonlinear Nanobubble Behaviour for Vascular and Extravascular Applications

Nanomedicines exhibit novel properties with structural versatility, improved pharmacokinetic profiles, and multifunctionality for advanced delivery strategies targeting infiltrative tumours while sparing surrounding normal tissue. Consolidating the abilities of traditional nanoparticles with conventional ultrasound agents by shrinking microbubbles to the nanoscale can have profound effects on bubble behaviour, bringing new possibilities as well as challenges. This dissertation aims to address current limitations of nanobubbles, laying the groundwork for their utility within and beyond the vasculature. Insights on nanobubble behaviour in vessel- and tissue-mimicking surroundings through theoretical and experimental approaches are presented. The first observation that nanobubbles can initiate sustained pressure threshold-dependent nonlinear scattering is shown, and found to be highly sensitive to nonlinear shell rheology. Novel direct acoustic evidence that nanobubbles can extravasate intact is then demonstrated upon different delivery avenues with real-time acoustic and visual observations in tumour-affected functional circulation at the microscale. An ultrasound-stimulated in situ conversion of microbubbles to nanobubbles is studied and compared to passive and ultrasound-mediated delivery of injected nanobubbles, with acute vascular events from ultrasound-stimulation of nanobubbles being visualized for the first time. Developing a tool for further examination of nanobubbles, their scattering is then systematically investigated at high frequencies with a view to establishing imaging schemes based on their physical behaviour. Pressure-calibrated amplitude modulation is employed on a commercial pre-clinical array system, resulting in enhanced contrast-to-tissue ratios onthe order of 10 dB in a phantom and in vivo. Collectively, the developments achieved in this thesis aim to extend bubble-mediated approaches through the integration of nanomedicine and ultrasound.

Keywords: Contrast Agent
Imaging
Microbubbles and Nanobubbles
Nanomedicine
Therapy
Ultrasound
Advisor: Zheng, Gang
Goertz, David E.
Effects of Repetitive Transcranial Magnetic Stimulation (rTMS) on Cannabis Use and Cognitive Outcomes in Schizophrenia

Effects of Repetitive Transcranial Magnetic Stimulation (rTMS) on Cannabis Use and Cognitive Outcomes in Schizophrenia Karolina Bidzinski nee KozakDoctor of Philosophy 2021 Institute of Medical Science University of Toronto ABSTRACTRationale: Schizophrenia is a debilitating psychiatric disorder, with poor functional outcomes. Problematic cannabis use among the schizophrenia population is high, with 26% diagnosed with comorbid cannabis use disorder (CUD), which negatively impacts psychosocial functioning. These patients also have greater difficulty quitting cannabis, which may reflect putative deficits in the prefrontal cortex. To date, there are still no established evidence-based treatments for this comorbidity. Aims: Primary: Determine effects of high frequency (20 Hz) repetitive transcranial magnetic stimulation (rTMS) on cannabis use outcomes in outpatients with schizophrenia and CUD. Secondary: Examine effects of active vs. sham rTMS on cannabis craving/withdrawal, psychiatric symptoms, and cognitive functioning. Hypotheses: Primary: Active vs. sham rTMS will result in significantly greater reductions of cannabis use and cannabis abstinences rates. Secondary: Active vs. sham rTMS will result in significantly greater reductions in cannabis craving/withdrawal symptoms, and positive and negative symptoms of schizophrenia, and greater improvements in cognition. Methods: A preliminary double-blind, sham-controlled randomized trial. A total of N=24 subjects were enrolled, and n=19 participants were randomized to receive either active (n=9) or sham (n=10) high frequency rTMS 5x/week for 4 weeks, combined with weekly behavioural support sessions. Cannabis use and symptomatology were monitored weekly through self-report and urine toxicology. A cognitive/neurophysiological battery was administered at pre (Baseline) and post (Day 28). Results: Although no significant differences in cannabis use from Baseline to Day 28 between active and sham treatment were found, contrast estimates indicated greater reductions in cannabis use in the active group (GPD: Estimate=0.33, p=0.207). A trend toward significantly greater reduction in craving score (MCQ Factor 3) over time was found in active vs. sham (Estimate=3.92, p=0.064). Significant reductions in PANSS positive (Estimate=2.42, p=0.018) and total (Estimate=5.03, p=0.019) symptoms over time were found in active vs. sham groups. Significant improvement in Continuous Performance Test (e.g., sustained attention) over time was found in active vs. sham groups (Estimate=6.58, p=0.048). rTMS was safe and well-tolerated, with a high retention rate of 17/19 (90%) outpatients completing the study. Conclusions: Our preliminary findings support the notion that rTMS is a safe and potentially effective treatment for comorbid CUD and schizophrenia.

Keywords: Cannabis
Cannabis Use Disorder
Comorbidity
Repetitive Transcranial Magnetic Stimulation
rTMS
Schizophrenia
Advisor: George, Tony P
Fate and Removal of Triclosan in Open–water Treatment Wetlands

Triclosan is an antimicrobial agent and one of the many emerging contaminants that is frequently detected in the environment. Triclosan is an endocrine disruptor that is able to accumulate in living organisms (i.e., fish, algae, humans). Triclosan can transform into various transformation products that are potentially toxic and can contribute to bacteria resistance against antibiotics. This research aimed at minimizing the accumulation of toxic by–products in open–water treatment wetlands for the safe transformation of triclosan. This work focused on triclosan phototransformation, and algae uptake and transformation. The results showed that the half–life of triclosan was generally shorter in solutions with a high pH (where the pH is greater than triclosan’s pKa at 8.2), and low dissolved organic carbon (DOC) concentration. However, in treatment wetlands, where the pH is around 7, triclosan phototransformation cannot be maximized unless the DOC is reduced, and the pH is increased. The use of Euglena gracilis strain Z was studied for its potential to (i) provide an additional transformation pathway for triclosan and (ii) naturally increase the pH of the water via photosynthesis. A series of multiple laboratory–scale algae reactors was carried out to investigate triclosan fate in open–water treatment wetlands. The pH of the algae–containing reactors increased during the 25–day experimental period for wetland water, autoclaved wetland water, and growth media. More than 90% triclosan concentration decrease was also observed in the reactors that used continuous (white) light. Data on kinetics, pathway apportionment, and transformation products showed that phototransformation, algae uptake and transformation, microbial transformation, and adsorption (at low pH) all contributed to triclosan elimination in these lab–scale algae reactors. Altogether, these results suggest that triclosan removal can be accomplished with open-water treatment wetlands while minimizing the accumulation of triclosan’s transformation products.

Keywords: Algae
Phototransformation
Triclosan
Wetland
Advisor: Passeport, Elodie
Programming Interval Training to Optimize Endurance Sport Performance

Interval training has become an essential component of endurance training programs because it can facilitate a substantial improvement in endurance sport performance. Interval training involves repeated bouts of high intensity exercise lasting from seconds to minutes in duration. There remains a lack of consensus concerning the optimal method to structure an interval training program. Therefore, the objective of this thesis is to determine the optimal method to program interval training to maximize endurance sport performance. The results of this thesis showed that interval training produced adaptations in the central and peripheral factors that influence maximal oxygen consumption (VO2max) that were dependent on the type of interval training. Interval training programs led to improvements in VO2max, maximal aerobic power and time-trial (TT) performance. The responses were highly dependent on individual and training characteristics. Training status was shown to be the primary baseline characteristics that influenced the response to interval training. With respect to programming variables, long duration intervals (4 min to 5 min) performed during high-intensity interval training (HIIT) produced greater improvements in TT performance compared to sprint interval training (SIT). Exercise performed at any intensity within the severe domain led to similar improvements in TT performance. Consistent training for at least 4-weeks was required to see maximal improvements with HIIT. However, the relationship between total work and performance improvements was not present with SIT. Meta-analyses are highly effective tools that can be used to create best practice guidelines for programming interval training.

Keywords: endurance performance
endurance sport
interval training
sport science
time-trial
Advisor: Thomas, Scott G
Low-complexity Forward Error Correction and Modulation for Optical Communication

A novel low-complexity architecture for forward error correction (FEC) in optical communication is proposed. The architecture consists of an inner soft-decision low-density parity check (LDPC) code concatenated with an outer hard-decision staircase or zipper code. The inner code is tasked with reducing the bit error probability below the level that allows the outer code to deliver on the stringent output bit error rate required in optical communication. A hardware-friendly quasi-cyclic construction is adopted for the inner codes. The concatenated code is optimized by minimizing the estimated data-flow at the decoder. A method is developed to obtain complexity-optimized inner-code ensembles. A key feature emerging from this optimization is that it pays to leave some inner codeword bits completely uncoded, thereby greatly reducing the decoding complexity. The trade-off between performance and complexity of the designed codes is characterized by a Pareto frontier. In binary modulation, up to 71% reduction in complexity is achieved compared to previously existing designs. Higher-order modulation via multilevel coding (MLC) is compared with bit-interleaved coded modulation (BICM) from a performance-versus-complexity standpoint. In both approaches, complexity-optimized error-reducing LDPC inner codes are designed for concatenation with an outer hard-decision code, for various modulation orders. Code designs for MLC are shown to provide significant advantages relative to designs for BICM over the entire performance-complexity tradeoff space, for a range of modulation orders. Codes designed for MLC can operate with 78% less complexity, or provide up to 1.2 dB coding gain compared to designs for BICM. A multi-rate and channel-adaptive inner-code architecture is also proposed. A tool is developed to optimize low-complexity rate- and channel-configurable concatenated FEC schemes via an MLC architecture. Compared to previously existing FEC schemes, up to 63% reduction in decoding complexity, or up to 0.6 dB coding gain is obtained. Code designs for MLC in combination with four-dimensional signal constellations are also considered. The design method is generalized to obtain complexity-optimized non-binary LDPC codes to concatenate with outer zipper codes. Gains of up to 1 dB over the conventional schemes are reported. The possibility of using a novel class of nonlinear codes in FEC design is also investigated.

Keywords: coded modulation
concatenated coding
low-complexity codes
low-density parity-check codes
performance-complexity tradeoffs
rate- and channel-adaptivity
Advisor: Kschischang, Frank R
Lifetime and Daily Discrimination and Mental Health in Sexual and Gender Diverse Individuals: Examining Risk and Protective Factors

Lesbian, gay, bisexual, transgender, non-binary, queer, two-spirit, intersex, asexual and other sexual and gender diverse (LGBTQ+) individuals are at increased vulnerability to experience negative mental health outcomes compared to their heterosexual and cisgender counterparts. A large body of scholarly literature suggest that stigma (often in the form of discrimination) contributes to stressors that may account for the increased mental health burden in this population. The Psychological mediation framework (PMF) indicates that emotion regulation and social support may be important mechanisms leading from stigma to mental health outcomes. The objectives of the present studies were to evaluate and expand the PMF by testing the effects of stigma on mental health (i.e., affectivity and depression) through emotion regulation and social support, and to examine the moderating effects of several risk factors (i.e., childhood abuse history, attachment insecurity) and protective factors (i.e., self-compassion). Daily diary data was used in Study 1 while Study 2 used cross-sectional baseline data to carry out objectives. In Study 1, participants (n = 84) submitted 592 daily surveys for an average of 7 days, reporting on their discrimination experiences, social support, emotion regulation, daily affect, and several risk and protective factors. Moderated mediation models were examined using multilevel, conditional process modelling. It was found that both within-person and across-persons, daily discrimination was indirectly related to daily negative affectivity, via emotion dysregulation, but not social support. Childhood abuse history and self-compassion moderated the daily discrimination- emotion dysregulation relationship. In Study 2, conditional process modeling was used to test pathways from lifetime LGBTQ+ discrimination to depression via social support and emotion dysregulation, with attachment insecurity as a moderator using cross-sectional data from 117 LGBTQ+ individuals. As expected, lifetime LGBTQ+ discrimination had an indirect effect on depression, via social support, and this effect was moderated by attachment insecurity. Social support had a direct and indirect effect on depression, via emotion dysregulation. Emotion dysregulation and social support are important mechanisms leading from discrimination to mental health in LGBTQ+ individuals, and understanding specific risk and protective factors can help to inform case conceptualization and treatment planning for LGBTQ+ affirmative interventions.

Keywords: attachment
emotion regulation
LGBTQ+
mental health
microaggressions
minority stress
Advisor: Gillis, Joseph R
Project-Based Learning: A Case Study of Early Data Analytics Learning in Undergraduate Mathematics

The overall goal of this study was to examine the design and impact of project-based learning (PBL) for early data analytics learning in undergraduate mathematics at a four-year research university in the United States. I documented the plans, activities and participant feedback gathered as part of the original funded program at the university, and delved further into the archival data to explore the feasibility and impact of introducing data analytics learning early in the undergraduate mathematics curriculum. The relationships between student development of knowledge, ability, and confidence during this PBL-infused program were also examined, and the benefits and challenges from the perspectives of the learner and the teacher were detailed.The study provided a successful example of how a PBL-infused approach could be used to effectively teach data analytics early in the mathematics undergraduate curriculum. The findings suggested that the early introduction to data analytics program resulted in additional learning, research and internship opportunities, and informed students’ undergraduate studies, choice of major, and other life choices such as plans for graduate studies and/or careers. Interactions and collaborations in visualizing problem solving in the context of projects using real-world data afforded the students additional opportunities to network with their peers, faculty, and university, industry, and/or community partners. This created a community of learners with shared goals and achievements. These collaborations and interactions supported students’ development of knowledge and ability, both of which were positively correlated with confidence in this early data analytics experience. This study illuminates the design features of the early data analytics learning and research experience, and offers a refined design framework for PBL-infused data analytics curricula in mathematics. The refined design framework includes: real-world content for greater accessibility, visualization of the problem solving, incorporating interactions and collaborations among all in the community of learners, and the promotion of knowledge, confidence and beliefs in support of lifelong learning. The potential of the case study and the refined framework to transform learning across STEM disciplines bolsters the potential broader impact.

Keywords: Big Data
Data Analytics
Problem-Based Learning (PBL)
Project-Based Learning (PBL)
Undergraduate Math
Undergraduate Research
Advisor: McDougall, Douglas E.
Perceived and Objective Cognitive Impairment in Depression: The Identification, Investigation, and Measurement of Cognitive Impairment Bias

A recently introduced construct – Cognitive Impairment Bias (CIB) – suggests that the common, but heterogeneous cognitive impairments reported in patients with depression and/or depressive symptoms may be related to biased perceptions related to one’s cognitive abilities. The current program of research examines CIB in a young adult sample with a range of depressive symptom severity. In the first study, CIB uniquely accounts for variation in depressive symptoms and functioning above and beyond objective measures of cognitive functioning. In the next study, CIB was shown to vary based on depressive symptom severity, distinguishing groups belonging to different depressive symptom severity groups, demonstrating large effects as a standalone distinguishing construct, but also when compared to objective measures of cognitive functioning. Finally, after highlighting that CIB is an important construct associated with depressive symptoms, warranting further exploration, the Cognitive Impairment Bias Scale (CIBS) was developed. Psychometric properties of the initial development of the CIBS are discussed. Collectively, results show that CIB is an important construct to consider for both clinicians and researchers. Future studies should seek additional evidence to support the validity of the CIBS in diverse clinical samples and research settings.

Keywords: cognitive impairment
cognitive impairment bias
depression
functional impairment
neuropsychology
subjective cognitive impairment
Advisor: Zakzanis, Konstantine K
Distributed Leadership in Ontario’s CAAT sector English Department Academic Coordinators

This study uses the theories of distributed leadership (DL) and the lens of hermeneutic interpretation to explore and describe the interactional tasks and functions that English department Academic Coordinators (ACs) across the province of Ontario carry out in their leadership work as an alternative to the traditional administrative systems. Interviews with 15 English department Academic Coordinators at Ontario anglophone colleges in the CAAT (Colleges of Applied Arts and Technology) system provided the key data for the study. Document analysis in the form of organizational charts, union and corporate documents as well as observational journaling were used to provide data to account for the ACs practices. Study findings indicate that CAAT ACs in English departments have a unique and influential role as both teacher leaders and boundary spanners. Participants suggested this was because their role required them to span both the macro-world of the college context as well as the micro-world of their own departments and faculty peers. Results from the data indicate that there are multiple challenges to these interactive and collaborative coordinator interactions. Participants suggested this was caused by clashing with other faculty and administration over their influence and ability to work through change in policy and teaching practice. The theoretical lens of DL helps to illuminate some of these challenges. Throughout the study, participants also described positive aspects of their work that were used in order to maintain connections, establish trust and organize the flow of communications and to attempt to use influence to lead their respective departments and the college staff from the bottom up. Their experiences may provide a descriptive entrance into a conversation about collaborative forms of leadership that are already being used in the CAAT system.

Keywords: Colleges
Distributed Leadership
Hermeneutics
Networking
Ontario
Advisor: Ryan, James
The Decorrelation Length and Time Scale - Diagnostic Tools to Visualize Spatial and Temporal Variability in Geophysical Fields

Atmospheric reanalyses and model data are becoming more commonly used. However, most reanalyses and global climate models have resolutions of ~50 km or lower --- scales too coarse to capture many topographic and coastal effects within various geophysical fields such as precipitation and wind speed. Although attempts have been made to assess the impact of horizontal model resolution, such as downscaling and power spectrum methods, it is still unclear how this impacts the representation of the spatial variability. This thesis presents the Decorrelation Length Scale (DCLS and Decorrelation Time Scale (DCTS), novel techniques to characterize and visualize spatial and temporal variability in geophysical fields at a grid-point level, that is able to investigate this impact. The main strength of the DCLS/DCTS provide insight into both the relative variability and geographical imprint of the source of variability. A set of reanalysis, hindcasts, and analysis datasets with a common lineage and with horizontal resolutions ranging from ~125 km to ~9 km were used in three case studies to validate and explore the utility of this new technique. The first case study validated the DCLS's utility as a diagnostic by showing that there are changes in the spatial variability of the precipitation over the Eastern Pacific that are not reflected in its mean structure. The second case study applied the same analysis technique as the DCLS to visualize temporal variability as well, showing that even resolutions of ~30-km do not capture the wind field's variability, especially in coastal and mountainous regions and also support the historic choice of wind farm development in the UK, namely, the southern/south-western tip of England as well as off the southern shore. Since the DCLS is not subject to uniform model bias, the third case study used this technique to study the spatial variability of the Congo Basin's hydrological cycle. This region has been historically understudied due to a lack of validation data and an interesting candidate for the DCLS analysis. DCLS results revealed that the main source of spatial variability in the P-E field over the Basin was uniformly from the precipitation field and that the spatial scales of the variability are less than 10 km.

Advisor: Moore, G.W.K.