VictorJuiz/thesis huggingface dataset:
Magnetar X-ray Spectra: An Utramagnetic QED Approach

This thesis considers the generation of the bright, broadband and non-thermal X-ray spectra of magnetars. These spectra are very sensitive to the distribution of electrons and positrons in the current-carrying magnetic field tubes; previous approaches considered generating the non-thermal components by modifying a seed thermal spectrum with resonant cyclotron upscattering on ultrarelativistic outflows, as well as through bremsstrahlung and synchrotron emission. The present approach constructs a Monte Carlo model of this persistent emission, where both ``AXP-like'' and ``SGR-like'' spectra are generated self-consistently as a result of the interaction of a warm magnetospheric plasma layer and a cold, dense neutron star atmospheric surface layer. This approach is motivated in part by evidence that the magnetospheric currents are strongly localized. In order to construct this model, a range of QED rates and cross sections are reviewed and calculated in the ultramagnetic background, many for the first time. In particular, the high electron-positron scattering and bremsstrahlung rates as well as the highly kinematically modified rates of two-photon pair creation and annihilation lead to a physical situation that differs qualitatively from previous models, including unique potential observational signatures.

Keywords: magnetic fields
plasmas
radiation mechanisms: general
relativistic processes
scattering
stars: magnetars
Advisor: Thompson, Christopher
Analysis of Visual Scanning Behaviour in Patients with Psychiatric Disorders

The diagnosis of psychiatric disorders often relies on clinician’s interviews and self-reported questionnaires. These techniques suffer from inter-observer variability and are often affected by communication difficulties between clinicians and patients. Analysis of visual scanning behaviour (VSB) is a method that can help to objectively characterise patients with psychiatric disorders. The main goals of this thesis are to a) develop novel techniques to analyse VSB and b) to develop novel experimental paradigms that are based on the analysis of VSB to assess cognitive processes. Data driven methodologies based on recurrent neural networks (RNN) were developed to learn visual scanning sequences of patients with mood disorders and patients with Alzheimer’s disease (AD). The method that was developed for patients with mood disorders is based on the analysis of VSB on human faces and can differentiate between patients with bipolar or unipolar depression with an area under the curve (AUC) of 0.879 (a gain of 0.276 relative to expert systems). The method that was developed to detect emotional blunting in AD patients could learn the individual’s “style of scanning” and can differentiate between apathetic and non-apathetic patients with AUC of 0.814 (0.646 for an expert system). Novel experimental paradigms were developed to assess the potential for conversion to AD in mild cognitive impairment (MCI) patients and a surrogate marker for the detection of structural damage to white matter tracts in patients with post-concussion syndrome (PCS). The paradigm for the assessment of MCI patients is based on measurements of novelty preference (NP) where repeated images appear after short delays (≤12.5 seconds). For short delays, NP is dependent on intact familiarity-based recognition memory. The marker for structural damage to white matter tracts in PCS patients is based on a novel visual scanning version of the matching familiar figures test (MFFT). VSB measures during the MFFT test were correlated to the microstructural integrity of the corpus callosum (r=-0.281, p=0.0141). In summary, the work in this thesis shows that by using novel paradigms and novel analysis techniques, VSB can provide valuable insights that can support the diagnosis and treatment of patients with psychiatric disorders.

Keywords: Deep learning
Eye tracking
Neural networks
Psychiatric disorders
Psychology
Visual attention
Advisor: Eizenman, Moshe
Examination of Black Entrepreneurs in Toronto, Canada: Critical Analysis of the Role of Financial Literacy

American entrepreneur Jim Rohn stated that “Formal education will make you a living; self-education will make you a fortune” . This research on lived experiences of Black businesses in Toronto has relied on self-education. Bogan and Darity (2008) argue that policymakers and scholars alike consider self-employment as an alternative to unemployment and a route out of poverty. This dissertation examines the historical and contemporary experiences faced by Black businesses in Canada, and in particular the Greater Toronto Area. In addition, this research examines the role of financial literacy education amongst the Black community. This dissertation argues that to understand the challenges within the Black business community, consideration of the complexities of Black identity, in antiquity and modernity, have shaped and influenced the Black narrative in not only stories of heroics and affirmation but betrayal, pain, and contestation, which has had a severe impact on economic prosperity within the Black community as a collective. Using theoretical frameworks that employ an analysis of anti-Black racism, anti-colonialism, and Indigenous knowledges as analytic tools, combined with literary exploration, this dissertation examines the impact of historic and systemic trauma on Black business owners with profound economic implications to their communities that continue to reproduce coloniality, discrimination, and racism. The findings of this research will add to the discourse on systemic, historical, and contemporary barriers that have hindered the growth of Black businesses in Canada. Unearthing the historical and contemporary barriers that have hindered the growth of more Black businesses in Toronto is needed to create an economic blueprint for future Black entrepreneurs to overcome economic, social, political, and psychological adversity. The findings enable scholars, policy-makers, and practitioners to better appreciate the possibilities and difficulties which characterize and frame attempts by Black entrepreneurs in Toronto that advance and/or hinder the sociopolitical and economic environment of Black bodies in Canadian communities.

Keywords: antiblack racism
Black Studies
education
entreprenurship
financial literacy
Advisor: Walcott, Rinaldo
Standard Language Ideology and World Englishes: A Multiple Narrative Case Study of Immigrant Educators’ Experiences in Canada

The spread of English and its users across the world has made imperative, an exploration of the language education histories and experiences of immigrant educators who use Outer Circle English varieties in Inner Circle countries. Using an interpretivist approach, this multiple narrative case study explores tensions between standard language ideology and Outer Circle varieties of English as well as their effects on the experiences of educators in Canada who use Outer Circle English. In Inner Circle countries, power imbalances embedded in ideologies about standard English and varieties of English from Outer and Expanding Circle countries can influence the trajectories of immigrant educators. World Englishes scholars have focused on history, definitions, teaching models, native versus non-native speaker dichotomies, language testing and discrimination, while narratives from Outer Circle English users, educated in both Inner and Outer Circle countries are noticeably lacking. Kachru’s concentric circles English model, organized along geopolitical and ideological lines, underpins this discussion about the status and spread of world Englishes. Intersectionality Theory is deployed as the main heuristic in order to explore the experiences and identities of educators who use Outer Circle English varieties. Further, Bourdieu’s notions of linguistic capital - wherein language is understood as capital mediated by social and power relations - facilitate this inquiry into language as a site-of-struggle, its effects, as well as resilience and agency. This study culls from data collected from ten educators in Canada who come from one former American colony and six former British colonies. Data include questionnaires, semi-structured interviews and language autobiographies. Participants’ language education histories and how their language-related experiences have shaped various facets of their lives inform the results of this study. Findings include narratives about heritage, education, teaching practices and research activities that showcase participants’ linguistic, personal, cultural and professional identities. Narrative inquiry fosters a deeper understanding of how participating educators’ experiences influence their multiple and fluid identities, teaching philosophies and pedagogical practices. Narrative provides opportunities for showing connections between participants’ histories, professional trajectories and belongingness. Implications for further research into linguistic variation, social selection and opportunities for educators who use Outer Circle English are discussed.

Keywords: educators
intersectionality theory
standard language ideology
world Englishes
Advisor: Gagné, Antoinette
Resilience Factors and Mental Health among LGBTQ Adults in Canada and the United States

There is compelling evidence suggesting that LGBTQ individuals face markedly higher rates of mood and anxiety disorder, as well as lifetime suicidality compared to heterosexual individuals. While most of the research on the psychological health of LGBTQ individuals has taken a deficit-based approach, more recent research has begun to explore the importance of resiliency in this population. Drawing on resilience theories, this study examined individual and community resources and stressors that contribute to the resiliency of LGBTQ individuals living in Canada and the United States and the degree to which these factors played a role in mitigating the adverse effects of mental health problems in LGBTQ individuals. Using multiple regression and mediation analysis, this study determined the predictability and mediation of model variables: internalized homophobia, coping skills (emotion-focused, problem-focused, and avoidant-focused), levels of optimism, attachment dimensions (anxious and avoidance), level of perceived social support, level of LGBTQ community connectedness, homonegative microaggressions, family acceptance, and overall psychological distress (depression, anxiety, and stress) on resilience. A total of 322 self-identified LGBTQ individuals were recruited through a variety of online venues. Results found optimism to be positive predictor of resilience and anxiety, depression, as well as anxious attachment dimension to be negative predictors of resilience. Further, higher levels of optimism, and lower levels of anxious and avoidance attachment related dimensions were all found to be significant partial mediators of the relationship between psychological distress and resilience. The results shed lights on ways mental health care professionals can promote resilience and mitigate the adverse effects of mental health in LGBTQ individuals.

Keywords: Attachment Dimensions
LGBTQ
Mental Health
Optimism
Resilience
Advisor: Gillis, Roy
Physiological Consequences of Sleep Loss in the Rat

In this thesis, I examined the homeostatic and physiological consequences of acute total sleep deprivation (TSD) and chronic sleep restriction (CSR) in the rat. I first developed a rat model of CSR using a walking wheel to confine sleep opportunities to designated times. I used this model to investigate the response of the sleep homeostat to a sleep deficit accumulated at different rates. I then compared the effects of CSR to the well-established acute ‘sleep deprivation syndrome’. Further, I considered a role for TSD in the production of reversible neuron damage. Finally, I investigated the impact of TSD and CSR on the integrity of neurons using an adapted model of mild traumatic brain injury (TBI). My research program led to the following conclusions: 1. CSR results in selective attenuation of the non-rapid eye movement (NREM) sleep homeostat, while leaving the rapid eye movement (REM) sleep homeostat intact. 2. CSR induces weight loss, body temperature and metabolic alterations that are qualitatively similar but quantitatively diminished compared to those of TSD. 3. TSD does not result in neuron damage in the rat sensorimotor cortex as measured by classical dark neurons (DNs). 4. Developing a sleep deficit from TSD or CSR prior to mild TBI does not cause exacerbation of neuron damage as measured by classical DN production. 5. There may be two under-represented demonstrations of neuron damage in the rat cortex: non-compacted DNs and light compacted neurons. When these neuron types are accounted for, a sleep deficit developed from TSD reduces the significant neuron damage produced by mild TBI. A sleep deficit developed by CSR does not afford the same neuroprotection as TSD.

Keywords: chronic sleep restriction
dark neuron
metabolism
sleep deprivation
sleep homeostasis
traumatic brain injury
Advisor: Peever, John
Advanced application of BOLD fMRI to study cerebrovascular and neurovascular physiology in people with Cerebral Small Vessel Disease

Cerebral Small Vessel Disease (CSVD) is one of the most common neurological disorders among older adults. Advances in neuroimaging have helped to identify the many structural changes seen in CSVD, of which lesions in the white matter, white matter hyperintensities (WMH), have been studied extensively. The CSVD literature scarcely addresses the relationship between structural changes and functional neurovascular and vascular outcomes. This thesis investigates blood oxygenation level dependent functional magnetic resonance imaging (BOLD fMRI) applications to better understand CSVD effects on cerebrovascular reactivity, functional activation, and brain tissue pulsatility. The first study of this thesis explores vasoactive capacity of people with a range of CSVD. I use a vascular transfer function to describe the extent to which and time taken for blood vessels to vasodilate in response to an external stimulus (i.e. CO2). The results demonstrated lower cerebrovascular reactivity in normal appearing white matter in those with more severe amounts of WMH, and further declined after one year in the CSVD population. The second study uses advanced BOLD fMRI image acquisition to observe neurovascular response through an attention-network probing task in CSVD. Widespread network activation in healthy older adults was altered in CSVD and healthy younger adults, and yet CSVD participants performed the poorest on the attention task. The third study investigates tissue-level cardiac-related pulsatility in the brain through repurposing of BOLD fMRI. These data revealed an association between insular pulsatility and middle cerebral artery pulsatility, the latter of which is an index of peripheral arterial stiffness and informs on possible mechanisms of CSVD cerebrovascular dysfunction. This thesis develops robust neuroimaging to show 1) functional deficits of CSVD, and 2) potential contributing factors to disease development. Establishment of functional outcomes is essential to understanding CSVD pathophysiology, the mechanisms behind its contribution to other neurodegenerative disorders, and the development of potential therapeutic targets.

Keywords: Blood oxygenation level dependent
Cerebral Pulsatility
Cerebral small vessel disease
Cerebrovascular reactivity
Functional magnetic resonance imaging
White matter hyperintensities
Advisor: MacIntosh, Bradley J
Associations between Allopurinol and Cardiovascular and Renal Outcomes in Diabetes

Diabetes is a leading cause of cardiovascular and kidney disease, and novel therapies to reduce these adverse diabetes outcomes are urgently required. Allopurinol, a uric acid-lowering therapy traditionally used for the treatment of gout, may reduce mortality and cardiovascular and kidney disease through reductions in oxidative stress and improved endothelial function, but this has not been well-studied in diabetes. Through three related projects, this thesis examines the associations between allopurinol and all-cause mortality, cardiovascular and renal outcomes in individuals with diabetes using population-based administrative health care data in Ontario, Canada. The first project examined patterns of allopurinol use and their predictors, to inform the design of subsequent studies. In 38,416 individuals with diabetes newly prescribed allopurinol, discontinuation and interruption of allopurinol were common. Female sex and greater severity of gout were associated with worse adherence. The second project evaluated the association between allopurinol-exposed time and all-cause mortality and cardiovascular outcomes in 38,416 new allopurinol users with diabetes. Allopurinol-exposed time was associated with a reduced risk of the primary composite outcome of all-cause mortality, atherothrombotic cardiovascular events (myocardial infarction, revascularization, stroke), or heart failure, which was primarily driven by a reduction in all-cause mortality. However, healthy user bias could not be completely excluded. The third project evaluated the association between allopurinol use and progression of chronic kidney disease (CKD) or development of end-stage renal disease (ESRD). In 5937 individuals with a gout flare and Stages 1 to 3 CKD at baseline (1911 with diabetes), renal outcomes did not differ between allopurinol users and non-users after weighting by the inverse probability of treatment. Based on the thesis results, allopurinol may reduce mortality and atherothrombotic cardiovascular events in individuals with diabetes, but does not appear to reduce heart failure, CKD progression, or development of ESRD. Defining allopurinol exposure in pharmacoepidemiology studies is challenging due to frequent interruptions and discontinuation. Thus, study designs incorporating time-varying exposure and time-varying confounders may be more robust. A clinical trial designed to evaluate the effect of allopurinol on atherothrombotic cardiovascular events in individuals with diabetes and hyperuricemia is strongly justified.

Keywords: allopurinol
clinical epidemiology
diabetes
gout
pharmacoepidemiology
Advisor: Hawker, Gillian A
Andante, Allegro o Silenzio: An Examination of Background Music Tempo on Facial Emotions, Electrodermal Responses, and Reading Task Performance

Current literature has established that learner’s emotions are an integral part of the learning experience (Pekrun Perry, 2014) and have significant effects on learning processes that optimize performance (Cunningham, Dunfield, Stillman, 2013), and attentional responses (Kärner Kögler, 2016). This present study examines the psycho-emotional and psychophysiological effects that variations in the tempo of background music have on learners who are completing reading comprehension tasks. To accomplish this, the present study examines how learning performance is modulated through the expressed emotions and bodily responses of participants and how our understanding of the relationship between the emotional experience and cognitive functions in learning tasks. A total of seventy-four (N= 74) participants studied in this project indicated that the tempo condition that participants were exposed to while competing their reading comprehension task did have a significant effect of predicting their performance outcome, emotional expressions, and psychophysiological responses. Results indicated that participants were more likely to have lower performance scores accompanied with the likelihood of greater expressions of fear, joy and contempt, along with greater skin conductance responses when listening to fast tempo music (150bpm). These results can suggest that a combined regulatory mechanism may be at play that helps indicate the combined effect that music may have on cognitive performance, attention allocation, and emotion regulation.

Keywords: Educational psychology
Emotion
Emotion regulation
Music cognition
Advisor: Woodruff, Earl
Noncoding Mechanisms in NF-κB Driven Vascular Endothelial Cell Inflammation

Vascular inflammation is an integral step in the initiation and progression of atherosclerosis.Mediated primarily by the nuclear factor kappa B (NF-κB) signaling pathway, vascular endothelial cells (EC) produce pro-inflammatory cytokines and adhesion molecules which facilitate monocyte recruitment and their subsequent transmigration through the endothelium. Noncoding mechanisms at the chromatin and noncoding RNA levels have been implicated in the development of atherosclerosis. Understanding these noncoding processes is imperative as they can provide ways to control and fine-tune aberrant vascular inflammation. Therefore, this dissertation aimed to elucidate how EC inflammation is regulated by long noncoding RNAs (lncRNAs) and NF-κB-chromatin interactions. LncRNAs are a heterogeneous class of noncoding transcripts >200 base pairs in length, many of which have been reported to act in cis to regulate the expression of their neighboring genes. Work in this dissertation has identified interleukin-1β (IL-1β) regulated neighboring mRNA-lncRNA pairs which were defined based on localization on the same topologically associated domains (TADs), divergent transcription, and shared regulatory elements. This approach led to the discovery of lncRNA-CCL2 which is transcribed divergently to CCL2, encoding a chemokine that is involved in monocyte recruitment. Moreover, lncRNA-CCL2 was found to positively regulate CCL2 transcript levels via interaction with RNA binding proteins. The second half of the dissertation used evolutionary conservation and NF-κB chromatin interaction status as a way to delineate which NF-κB binding sites are likely to regulate gene expression. It was found that accessible chromatin regions bound by NF-κB prior to tumor necrosis factor alpha (TNFα) treatment showed the highest degree of evolutionary conservation and were enriched near TNFα up-regulated genes. Furthermore, deletion of several TNFα pre-bound and conserved NF-κB sites, particularly within the CCL2 super-enhancer, showed them to be important for gene regulation. Altogether, these findings increase our understanding of the noncoding mechanisms implicated in vascular inflammation and in the future could be targeted to selectively fine-tune the EC inflammatory response.

Keywords: CCL2
endothelial cells
epigenetics
long noncoding RNA
NF-kB
super-enhancer
Advisor: Fish, Jason E