VictorJuiz/thesis huggingface dataset:
Isotope shift spectroscopy of ions in cryogenically cooled neutral plasmas

This thesis describes precision measurements of isotope shifts of Nd+ ions using a novel cryogenic ion source. Isotope shift measurements are useful in searching for a hypothetical light boson that couples with electrons and neutrons, and which could be the long-sought-after dark matter particle. Isotope shifts of two transitions of the same element, scaled by a mass-dependent factor, can be plotted against each other to make a King plot. The nonlinearity of such a King plot can be used to constrain the mass of the new physics boson and its coupling strength to electrons and neutrons (denoted as yeyn). In this experiment, we take advantage of five stable spin-zero isotopes of neodymium to measure the isotope shifts of two optical transitions in Nd+ with MHz-level accuracy. The experiment employs the cryogenic ion source, which is designed to produce cold and dense neutral plasmas by laser ablation of metal targets, followed by cryogenic buffer gas cooling. In this ion source, large ion densities (≤ 109 cm-3) can be obtained at temperatures as low as 6 K. The lasers used for the isotope shift measurements were stabilized using a novel transfer interferometer laser stabilization method, which is a simple and robust way to stabilize multiple lasers with different frequencies. The King plot analysis of the Nd+ isotope shift measurements constrains yeyn ≤ 1.4×10-9, which is comparable to the constraints placed by state-of-the-art isotope shift measurements on other atomic ions. We also discuss the prospects for further improvements to the accuracy of Nd+ isotope shifts using telecom-band optical clock transitions identified in this thesis, which could probe for new physics bosons with yeyn as low as 10-15, and lead to extremely precise tests of physics beyond the standard model.

Advisor: Vutha, Amar
Climate Clubs: Minilateral Approach to Climate Change

The global challenge of climate change can be solved with effective mechanisms. In this context, commitments for combating climate change should be scrutinized with high deterrent sanctions or strong incentives. This thesis explores climate clubs, which is offered as one of the solutions to climate change, and how to encourage and accommodate countries with different concerns into this mechanism. The paper first addresses the issues of free-riding, carbon leakage, and competitiveness, which are the problems of current climate change mitigation efforts. Then, it examines which trade tools can be employed as a linking instrument within the climate clubs to achieve effective results and encourage the membership of various countries. Subsequently, the compatibility of these linking tools with WTO law was researched. Finally, the structure of climate clubs is evaluated in the context of developing countries.

Keywords: Climate Clubs
WTO Law
Advisor: Green, Andrew J
CYP2D is Functional in the Brain and Alters Haloperidol-induced Side Effects

The human cytochrome P450 2D6 (CYP2D6) enzyme metabolizes numerous neurotoxins and centrally-acting drugs, including first generation antipsychotics such as haloperidol. These antipsychotics are used to treat schizophrenia and can cause adverse events in patients following acute and chronic intake. CYP2D6 expression in the liver is essentially uninducible and is regulated by genetics, whereas CYP2D6 expression in the brain is dependent on many factors, including CYP2D6 genetic variation, brain-specific induction of CYP2D6, and drug-drug interactions. Variation in human CYP2D6 activity in the brain may alter local drug and metabolite levels sufficiently to change drug response, including therapeutic efficacy and adverse events. This thesis investigated the impact of brain-specific manipulation of CYP2D on haloperidol-induced responses. CYP2D in rat brain (but not in rat liver) was inhibited by 24-hour pre-treatment with intracerebroventricular propranolol and induced by 7-day subcutaneous nicotine treatment. We found that acute haloperidol-induced catalepsy was decreased after inhibiting, and increased after inducing, CYP2D selectively in rat brain. In contrast, chronic haloperidol-induced vacuous chewing movements were increased after inhibiting, and decreased after inducing, CYP2D selectively in rat brain. Further, we investigated human CYP2D6 drug metabolism in vivo using CYP2D6-transgenic mice (TG) which express human CYP2D6 and mouse CYP2D, and in wildtype mice (WT). Mouse CYP2D and human CYP2D6 in TG liver, and mouse CYP2D in WT liver, were inhibited by 24-hour pre-treatment with intraperitoneal propranolol. In contrast, a 24-hour pre-treatment with intracerebroventricular propranolol irreversibly inhibited human CYP2D6 in TG brain, but not mouse CYP2D in TG or WT brain; there was no inhibition of hepatic CYP2D in TG or WT. Brain-specific inhibition of human CYP2D6 in TG brain reduced acute haloperidol-induced catalepsy, without affecting plasma haloperidol levels. This thesis demonstrated that CYP2D, including human CYP2D6, in the brain plays a role in in vivo haloperidol-induced responses. We have developed a new tool that enables the investigation of human CYP2D6 in brain on in vivo drug-response. In conclusion, we demonstrated that human CYP2D6 in the brain is functional and sufficiently able to alter drug-induced behaviour, suggesting a role in altering therapeutic efficacy and adverse events in humans.

Keywords: Cytochrome P450 2D6
Drug metabolism
Haloperidol
Neurotoxicology
Propranolol
Advisor: Tyndale, Rachel F
The Moral and Ethical Dimensions of Dialogic Critical Literacy Learning

Dialogic learning is an essential element of the high school English language arts (ELA) classroom and the foundation of critical literacy. Critical literacy dialogues explore controversial and conflictual issues of social justice, including topics of power, race, gender, and politics. However, while the examination of power and social justice that promote reflection and understanding is an objective of critical literacy, some dialogues may become contentious and raise ethical issues for teachers who acknowledge the importance of critical literacy but are pedagogically unprepared for dialogical conflict. Teachers must recognize their ethical role in determining the quality of students’ education and the ethical concerns of politicized classroom dialogues. Notwithstanding the Manitoba English language arts (ELA) curriculum’s promotion of critical literacy praxis, only a limited examination of the ethical complexities within critical literacy research has been conducted. In response, this philosophical inquiry examines the theoretical foundations of critical literacy and dialogic learning, their respective moral and ethical dimensions, and explores the ethical implications teachers and students face when engaged in conflictual dialogic learning in the ELA classroom.

Keywords: critical literacy
dialogic
ethics
moral
Advisor: Campbell, Elizabeth
Composition and Dimensionality Engineering of Perovskite Materials for Photovoltaic Applications

In recent years, metal halide perovskites have attracted research interest due to their remarkable optoelectronic properties, including strong optical absorption and long carrier diffusion lengths, combined with low-cost fabrication. As soft ionic solids, metal halide perovskites exhibit versality in chemical composition and structural dimensionality: this enables tunable bandgaps and luminescence. In this thesis, I focus on engineering the composition and dimensionality of metal halide perovskites with the goal of advancing photovoltaic applications. I begin by developing and investigating a cation-engineering strategy that enables wide-bandgap perovskites to show high defect-tolerance. Cation-engineering increases the device performance of wide-bandgap perovskite solar cells to exceed 20% PCE. I attribute the excellent performance to the reorientation of MA dipoles, which heals deep-level defects. Next, I study carrier diffusion in mixed-cation perovskites. MA-based perovskite thin films exhibit a high carrier diffusivity of 0.047 cm2s-1, whereas CsFA films show an order of magnitude lower carrier diffusivity. Experimental characterization suggests that the graded composition of CsFA films curtails electron diffusion. The incorporation of MA leads to a uniform composition of CsMAFA films, giving rise to a diffusivity of 0.034 cm2s-1. I then explore dimensionality engineering in narrow-bandgap perovskites. I develop a processing approach that enables the passivation of 3D perovskite surfaces using ultra-thin 2D perovskite passivants. The 2D layer retards the oxidation of 3D perovskites while maintaining their charge-transport properties. This enables a certified PCE of 18.95% and a 200-hour operating stability for narrow-bandgap perovskite solar cells. Lastly, I study perovskite nanoplatelet (PNPL) synthesis and phase-control, as well as energy transfer within mixed-phase PNPLs. I find that tuning the phase-distribution of PNPLs engineers their photoluminescence quantum yield and Stokes shift, allowing the corresponding perovskite luminescent solar concentrators to exhibit low optical loss. This work showcases the crucial role of composition and dimensionality in extending the applicability of perovskites to tandem and building-integrated photovoltaics. It concludes with a discussion of paths towards the eventual commercialization of these PV technologies, in light of the need to improve their efficiency and stability, to achieve up-scaling, and to address concerns regarding material toxicity.

Keywords: Composition engineering
Dimensionality engineering
Luminescent solar concentrators
Metal-halide perovskite
Photovoltaics
Tandem solar cells
Advisor: Sargent, Edward H.
World Mission and Higher Education Internationalization: A Comparative Study of Christian Universities in South Korea and Canada

This thesis explores the nature of internationalization activities at two Christian higher education institutions comparatively—one in South Korea and the other in Canada. A qualitative study, it examines the question of the extent to which an institution’s internationalization policies and programs reflect the core values of the evangelical Christian faith stated in their mission and vision statement. A conceptual framework was created using Jane Knight’s (2004) framework for internationalization and the concept of Holistic Christian world mission found in the Lausanne Covenant. This enables understanding of how the current theories of Christian world mission and the secular ideas of internationalization come together to influence the institutional mission. The history and context of each school also were studied to see how much they influence the internationalization strategies. The study found the evangelical core values of the Christian faith in the mission statements at each of the Christian higher education institution are strongly reflected in internationalization policies and programs. They are the driving force behind what they do in terms of internationalization ‘at-home’ and abroad. This is due to underlying motivation for the strategies of internationalization being the scriptural calling of Holistic Christian world mission. Consequently, a new values-based conceptual framework for internationalization emerged. The study revealed there are several intersections between the secular notions of internationalization and the values of Christian world mission in the precepts of the Lausanne Covenant. The socio-cultural rationales of Social and Community Development fuse closely with the motivations of Christian Social Responsibility which are tied with values of compassion, justice, reconciliation and mercy. Knight’s (2004) rationale of global citizenship development also intersects with the Great Commission’s calling to reach out to all nations. It is also linked to the Second Greatest Commandment of love and service for others and building of community through Christian discipleship and mentoring. The secular political rationale of technical assistance alongside peace and mutual understanding has values in common with those of the Lausanne Covenant, including Christian and Social Responsibility, Churches in Evangelistic Partnership, and Cooperation in Evangelism. However, context does affect the degree and types of engagement in internationalization programs.

Keywords: Canada
Christian higher education
Christian world mission
comparative education
internationalization
South Korea
Advisor: Hayhoe, Ruth
Exploration of Chemical Interactions between Streptomyces and Eukaryotes

Bacteria live in complex communities that interact with other organisms. One way they interact is by making chemicals that target one another. In this work, I characterize two new chemically-mediated ways that bacteria interact with eukaryotes. First, I show that bacteria can kill insects by making toxic molecules. Flies that ingest spores of Streptomyces bacteria die as a result of ingesting strains that make toxic molecules. I also show that this toxicity is facilitated by airborne odors that abolish the insect’s progeny. Second, I show that fungi can trigger Streptomyces to enter a new mode of growth called ‘exploration’. Here, I characterize ‘exploratory’ growth and identify how it is triggered by airborne chemicals and yeast’s ability to modify the growth environment. Overall, this thesis describes two new ways in which bacteria and eukaryotes interact and highlights how chemicals play an important role in these interactions.

Keywords: Bacteria
Fruit fly
Insect
Metabolites
Microbiology
Streptomyces
Advisor: Nodwell, Justin R
Symmetric Variational Inference with High Mutual Information

This thesis introduces the Mutual Information Machine (MIM), an autoencoder model for learning joint distributions over observations and latent states. The model formulation reflects three key design principles: 1) low divergence, or symmetry, to encourage the encoder and decoder to learn consistent factorizations of the same underlying distribution; 2) high mutual information, or approximate invertibility, to encourage an informative relation between data and latent variables; and 3) low marginal entropy, or compression, which tends to encourage clustered latent representations. Taken together, these objectives yield a cross entropy loss for learning latent variable models. The resulting form of amortized, symmetric variational inference stands in contrast to the use of an evidence-lower-bound (ELBO) in VAEs, and the use of adversarial learning that is common with other models formulated in terms of a symmetric divergence. In this thesis we systematically probe different terms in the variational bound, providing intuition about MIM. Experiments show that MIM is capable of learning a latent representation with high mutual information, and good unsupervised clustering, while providing data log likelihoods comparable to VAE. We demonstrate state of the art results on image and language data.

Keywords: Bayesian Inference
Encoder-Decoder
Mutual Information
Representation Learning
Variational Inference
Advisor: Fleet, David J
Organometallic Chemistry and Catalysis of Iron with Noninnocent Ligands

The development of iron catalysts is attractive owing to the ready availability, relatively low cost and low toxicity of iron, its oxides and many of its salts comparing to noble metals. Iron complexes are capable of not only the standard two-electron processes, but also single electron transfer reactions that are less prevalent in noble metal chemistry. In Nature, many iron-containing metalloenzymes make use of the noninnocent properties of ligands coordinated to the iron center in their active sites. Inspired by this, my thesis examines the fundamental coordination chemistry and catalysis of iron complexes using noninnocent ligands. The first part (Chapter 2−4) of my thesis describes the synthesis and reactivity of iron complexes bearing bidentate picolyl−NHC (NHC = N-heterocyclic carbene) ligands In Chapter 2, the coordination chemistry and reactivity of picolyl−NHC iron and ruthenium complexes were explored, which includes the diverse coordination modes of picolyl−NHC ligands upon deprotonation, metal-ligand cooperation, and small molecule binding. In Chapter 3, an unusual ligand rearrangement of a deprotonated picolyl−NHC ligand on iron and ruthenium was investigated. Chapter 4 describes the iron-catalyzed geminal-specific alkyne dimerization. The second part describes (Chapter 5) the synthesis and reactivity of iron complexes bearing bidentate o-phenylenediamide ligands including the syntheses of biomimetic [2Fe2S] clusters and their catalytic reactivity in catalytic silylation of dinitrogen.

Keywords: catalysis
iron
noninnocent ligands
organometallic
Advisor: Song, Datong
Impacts of Household Characteristics, Activities and Building Characteristics on Indoor Concentrations of Semi-volatile Organic Compounds

When compared to outdoors, the indoor environment often has higher concentrations of some SVOCs, such as brominated flame retardants (BFRs), organophosphate esters (OPEs) and phthalates that are used as additive flame retardants and plasticizers from consumer products and building materials. Some outdoor SVOCs, such as polycyclic aromatic hydrocarbons (PAHs), can be transported into indoor environments, increasing indoor exposures to these compounds. With the increasing concerns about the implications of exposure for human health, attention has turned towards concentrations of SVOCs in indoor environments, particularly in residential dwellings where North Americans spend more than 60% of their time. This thesis documented concentrations of these SVOCs in residential buildings, focussed on the exposure disparities in SVOCs according to socio-economic status (SES), and developed SVOC sampling methods in low-SES homes. Quantitative filter forensics (QFF) was extended to portable air cleaners with portable filters to quantitatively estimate indoor particle-bound SVOCs, overcoming the limitations of traditional QFF requiring forced-air heating, ventilation and air conditioning (HVAC) systems, while also improving indoor air quality by removing particular matter (PM). This thesis also advanced knowledge on the impacts of household characteristics, activities and building characteristics on indoor SVOC concentrations. The research found SVOC exposure disparities according to SES in Canada, reinforcing the importance of better understanding of the intersection between contaminant exposure, housing quality, household characteristics, and activities that can elevate SVOC levels, and SES, with the aim of reducing exposures from residences in an equitable manner.

Advisor: Diamond, Miriam L.
Siegel, Jeffrey A.
Early Risk Stratification of Patients After Resuscitation from Out-of-hospital Cardiac Arrest

Introduction: Over 400,000 people suffer an out-of-hospital cardiac arrest (OHCA) each year in Canada and the United States of which less than 10% survive to hospital discharge. Cardiac arrest is a heterogenous condition and patient outcomes are impacted by a multitude of factors. Post-cardiac arrest prognostication is recommended to occur 72 hours after return of spontaneous circulation, however it is not known if there are factors that can be utilized early in the post-cardiac arrest period to predict patient outcome. The objective of our study was to develop a novel clinical prediction rule that could be used to risk stratify patients early in the post-cardiac arrest period. Methods: We conducted a systematic review and meta-analysis to identify predictors of survival to include in our risk stratification model. We then performed a retrospective cohort study to derive and internally validate a number of statistical models to risk stratify cardiac arrest patients. We included data from 2010 to 2015 from the Epistry Cardiac Arrest database in Toronto and included both pediatric patients (cohort 1) and adult patients (cohort 2). Within each cohort we developed risk stratification models for all paramedic-treated OHCA and for patients who had a sustained in-hospital ROSC (>20 minutes). Using the results of our systematic review, as well as clinical expertise, we included a number of known predictors of patient outcome prediction and used ordinal and logistic regression analysis to derive our models. Models were internally validated using bootstrap validation. Results: We included a total of 18,527 adult and 379 pediatric patients from the Toronto ROC-Epistry Cardiac Arrest database between 2010 and 2015. In adult patients we were able to derive a clinical prediction model using Ustein variables, GCS motor score, duration of resuscitation, and pupillary response that predicted good neurological outcome with an AUC of 0.89 after internal validation. For pediatric patients we were able to predict good survival with an AUC of 0.81 using Utstein variables and duration of resuscitation. Conclusion: We were able to derive and internally validate a model to provide early risk stratification to cardiac arrest patients early in the post-cardiac arrest period. Future steps are to externally validate this model in another healthcare setting.

Keywords: Clinical Prediction Rule
Observational Research
Out-of-Hospital Cardiac Arrest
Paramedic
Advisor: Morrison, Laurie J
Modelling and Experimentation for Temperature Prediction of a Serpentine Belt Drive System

The scope of this thesis includes the development of three thermal models that can predict thermal distributions in an arbitrary serpentine belt drive system. The wide use of fibre-reinforced polymers (FRPs) pulleys in transmission systems has improved the systematic dynamic respond time and efficiency but also increased the possibility of pulley thermal destruction. To overcome this issue, this thesis presents three innovative and advanced thermal models for efficiently and accurately calculate temperature distributions. The first model uses the classical heat partitioning equations and analytically develops ordinary differential equations (ODEs) to calculate the thermal distribution inside irregular geometric structures of a pulley in the pulley thermal analysis. The second model adds a new set of analytical equations to determine the thermal flows of each pulley and belt temperature and integrate the pulley thermal analysis in the first model to calculate the temperature plots of pulleys. The third model replaces the previous analytical pulley thermal analysis with an innovative analytical-numerical method. It modifies pre-calculated numerical thermal simulations based on baseline conditions to deliver temperature plots for pulleys in working scenarios, so that it could maintain the fast solving speed and high accuracy. The substantial advantage of these models is that the time currently consumed by existing methods can be reduced to a few seconds without compromising the accuracy of the results. Validation experiments were conducted to obtain temperatures in the test cases, and these results demonstrate good agreement with the calculated temperatures. The temperature deviation between the calculated and experimental results are below 20% of absolute temperature rise and the solution time is less than ten seconds, making these models presented here successfully applicable for belt system design and materials research for pulleys.

Keywords: analytical algorithm
numerical simulation
serpentine belt drive
thermal analysis
Advisor: Behdinan, Kamran