VictorJuiz/thesis huggingface dataset:
Holocene Perspectives on Hydrogen Isotope Ratios of Boreal Plant Waxes in Northwestern Canada

This thesis provides novel insights into plant wax characteristics and fractionation in high latitude boreal forests in the Holocene. The isotopic composition of precipitation is a tracer for climatic changes. The hydrogen isotopic composition of plant waxes (δDwax) in sediments is a proxy for precipitation δD and paleoclimate but is offset from δDprecip due to a large net fractionation from several biotic and abiotic factors. The net fractionation is constrained for the northern boreal forest based on topsoils from a 13-site network in NW Canada. This will help future studies quantitatively reconstruct δDprecip from plant waxes. This thesis also presents the first δDwax record that extends through the full Holocene in Eastern Beringia from a lake sediment core in SW Yukon. Good coherence with other isotope proxies in the region suggests that this record accurately reconstructs variability in δDprecip and is likely driven by changes in atmospheric circulation and aridity.

Keywords: Beringia
Holocene
n-Alkanoic acids
Net fractionation
Plant waxes
Stable hydrogen isotopes
Advisor: Porter, Trevor J
An Ontario Primary Health Care System to Support a Cavity-Free Future

Fluoride varnish (FV) is a proven intervention for preventing early childhood caries. Due to frequent contact with children, primary healthcare professionals may be ideally situated for FV application. Currently, public health units across Ontario are implementing FV in primary care. Yet challenges remain at the political, professional, and practice levels. This study aims to understand the perspectives of key stakeholders on making FV application routine primary care practice in Ontario. Our findings suggest that there is an opportunity for interdisciplinary care and motivation for this intervention. However, we found that concerns related to funding, oral health knowledge, and existing inter-professional relationships may impede implementation. With respect to introducing a dental intervention into medical practice, the many factors required to implement change may not be in alignment. However, representatives across all fields are motivated and have identified opportunities for change that may form the foundation for this program in the future.

Keywords: Dental public health
Early childhood caries
Fluoride varnish
Prevention
Primary healthcare
Advisor: Quiñonez, Carlos
The Geographic Imaginaries of Empire: Migration, Tourism, and Constructions of Difference in Panamanian Travel Narratives

Panama’s tourism industry has flourished since 1990 to become one of the premiere travel destinations in Central America as described by tourism literature. Using historical geography as its methodology, this thesis offers an analysis of how colonial logics of empire remain embedded in the Panamanian tourism industry and nation building agendas. In particular, the discourse analysis of Panamanian travel narratives in archival and contemporary travel literature has revealed both substantial transformations and persistent congruities of imperial discourse from 1880-2017. The findings of this project demonstrate how hegemonic Euro-American geographic imaginations help construct tourism materials and influence tourist behaviour in Panama. In particular, themes of wilderness and nature, white supremacy, and America exceptionalism emerged from the analysis of tourism literature as the primary factors contributing to the conceptual and material organization of Panamanian space in travel literature. These themes are contextualized within broader discussions of empire studies and amenity migration literature.

Keywords: colonialism
imperialism
migration
Panama
tourism
travel
Advisor: Mollett, Sharlene
“I’m still here”: an Ethnographic Exploration of Public Twitter Use among People Living with Advanced Cancer

Twitter is the most public of all social media platforms, and yet some users turn to this platform to share intimate details about their health. This ethnography explores public Twitter use among people living with advanced cancer with the aim of describing their Twitter activities and their perspectives on their use. Six latent themes were generated by analyzing 2,731 original tweets published by 8 authors and interview transcripts from 10 participants: 1) Constructing Identity Through Textual Selfie, 2) Resisting Social Death, 3) Accounting for Time, 4) Finding Freedom in Obscurity, 5) Creating a Living Legacy, and 6) Fighting for What’s Right. Through these themes, I argue that the technological affordances of Twitter can be used to counteract the inhibiting aspects of liminality. In using Twitter publicly, they declare ‘I’m still here’ to themselves, the people around them, and the world at large.

Keywords: cancer
digital ethnography
liminality
palliative
social media
Twitter
Advisor: Wiljer, David
The Assessment of Hanging Behavior as a Measure of Mouse Welfare

A decline in mice welfare can be indicative of underlying pathology. Often, these changes in mouse behaviors are difficult to detect before the pathology has significantly advanced. Our experiments have revealed that cage-lid hanging, a “luxury” behavior in mice, can serve as an indicator of welfare in different models of pain. The hanging behavior is identified as an event where a mouse climbs onto the metal lid of the laboratory cage, suspending itself off the cage floor. The goal of this project was to characterize and evaluate the hanging behavior of mice as a robust early indicator of a decline in physiological welfare. I observed that both acute and chronic pain models robustly reduced the frequency and duration of hanging behavior in mice. My results demonstrated that hanging behavior is a marker of mouse physiological and psychological welfare, that can be easily incorporated to facilitate the early detection of disease.

Keywords: Animal Models of Pain
Hanging Behavior
Monitoring Animal Welfare
Pain
Advisor: Bonin, Rob
Real-World Multitasking Challenges in Younger Adults and Older Adults with and without Subjective Cognitive Decline

Age-related changes in postural control and/or cognition can be detrimental to multitasking performance. Previous studies investigating these effects have used paradigms not reflective of real-world challenges. Therefore, using a realistic multitasking paradigm in a virtual environment, this study examined age-related effects of performing a listening task while maintaining balance under varying levels of sensory/motor/cognitive challenge. Performance of individuals at potentially greater risk of cognitive decline (i.e., those with subjective cognitive decline (SCD)) was also evaluated. Results showed that older adults’ postural and listening performance was worse than younger adults, particularly under challenging conditions. Older adults with and without SCD exhibited comparable performance across conditions apart from the most challenging conditions, during which those with SCD demonstrated unexpectedly superior postural stability compared to those without. These findings demonstrate age-related decline in postural control and listening abilities, and suggest a prioritization of posture. Those with SCD did not demonstrate greater performance decrements.

Keywords: Aging
Auditory processing
Dual-tasking
Postural control
Subjective cognitive decline
Advisor: Campos, Jennifer L
Attention Deficit Hyperactivity Disorder Symptoms and Nonsuicidal Self-Injury among Clinically-Referred Children and Youth

Nonsuicidal self-injury (NSSI; direct and deliberate damage of bodily tissue) is a widespread concern among clinically-referred youth. Individuals with Attention Deficit Hyperactivity Disorder (ADHD) may be at increased risk for NSSI engagement; however, ADHD consists of heterogeneous symptomatology, and there may be differential risk based on varying symptomatology. The current study investigated differential risk for NSSI engagement associated with selected hyperactive/impulsive symptoms and inattentive symptoms in a sample of 1006, 8-18-year-old children/youth from Ontario, Canada. The Children and Youth Mental Health Assessment (ChYMH) was used to collect all measures at intake into clinical care. Three binary logistic regression analyses were conducted to assess the predictive ability of selected hyperactivity/impulsivity symptoms, selected inattentive symptoms and a combination in predicting NSSI. Only the hyperactivity/impulsivity symptoms were significantly predictive of NSSI engagement over and above age, sex, anxiety symptoms and social disengagement. The results are discussed in the context of implications for prevention/intervention.

Keywords: ADHD
Attention Deficit Hyperactivity Disorder
Child and Youth Mental Health Assessment
hyperactivity/impulsivity
inattention
Nonsuicidal Self-Injury
Advisor: Hamza, Chloe A
Transition to Adult Care for Youth with Severe Mental Illness: Does Continuity with Primary Care Matter?

Objective: To analyze the association between primary care continuity and acute mental health care services following transition to adult care. Methods: Population-based retrospective cohort study using linked administrative health data of youth ages 12-17 with schizophrenia (SZ), eating disorders (ED), or mood and affective disorders (MAD) admitted between April 1, 2002 and April 1, 2010 in Ontario, Canada. Poisson regression models tested the association of primary care continuity and mental health outcomes after transition. Results: Among 3183 youth with severe mental illness, the majority (n=2,052, 64.5%) received continuous primary care during the transition period. Compared with continuous care, no primary care (n=190) during transition was associated with a 52% increased risk of a mental health admission following transition (aRR 1.52, 95% CI 1.12, 2.05). Conclusions: In the context of decreasing specialist mental health visits, ensuring adequate access to primary care during the transition period may improve outcomes in young adulthood.

Keywords: Adolescent
Adult Care
Mental Health
Primary Care
Transition
Young Adult
Advisor: Guttmann, Astrid
A Longitudinal Spatiotemporal Analysis of Gait after Traumatic Brain Injury and an Assessment of Rhythmic Auditory Stimulation as a Gait Training Technique

Traumatic brain injury (TBI) can result in an array of motor and cognitive impairments. Walking difficulties are common following injury and can limit an individual’s ability to regain independence and achieve community integration. Rehabilitation is commonly used to treat gait-related issues and is in constant need of advancement and refinement. This thesis investigates: (1) the longitudinal change in spatiotemporal features of gait in the first year following TBI and the relationship between these changes and community integration, and (2) the feasibility of rhythmic auditory stimulation (RAS) as a gait training intervention to address chronic gait impairments of individuals living in the community with a TBI. Patterns of longitudinal spatiotemporal change are described and distinctions between severity groups are clarified. Next, the concurrent and predictive relationship between gait and community integration is elucidated. Lastly, the feasibility of RAS as a gait training technique in chronic TBI is further explored.

Keywords: Gait
Longitudinal
Rhythmic Auditory Stimulation
Traumatic Brain Injury
Advisor: Patterson, Kara
Brooks, Dina
Microfluidics and Nanofluidics for Unconventional Resources in Micropores and Nanopores

Unconventional resources play a crucial role in meeting the current global energy demand, however, production from these formations is challenging. The challenge mainly stems from either the extreme fluid properties (oil sands) or extreme rock properties (shale and tight sandstone). Primary production from unconventional reservoirs is very low which motivates testing and developing recovery strategies to improve the reservoir production. Micro/nanofluidic technologies have shown to be a promising tool to quantify the pore-scale recovery efficiency of different methods with a tight control over the operating conditions, i.e. pressure, temperature, and composition. In this work, we designed and developed two distinct micro/nanofluidic platforms to test some of the recovery methods for both bitumen and tight oil systems. This work highlights the unique potential of microfluidic and nanofluidic methods in resolving the pore-scale behavior of enhanced oil recovery processes under relevant reservoir conditions.

Keywords: Microfluidics Nanofluidics
Advisor: Sinton, David
TRANEXAMIC ACID IN THE TREATMENT OF RESIDUAL CHRONIC SUBDURAL HEMATOMA: A SINGLE-CENTRE, OBSERVER-BLINDED, RANDOMIZED CONTROLLED TRIAL (TRACE)

Chronic subdural hematoma (CSDH) is a frequent consequence of head trauma, particularly in older individuals. Given the aging of populations globally, its incidence is projected to increase substantially. Hyperfibrinolysis may be central to CSDH enlargement by causing excessive clot degradation and liquefaction, impeding resorption. The only current standard treatment for CSDH is surgery, however, up to 31% of residual hematomas enlarge, requiring reoperation. Tranexamic acid (TXA), an antifibrinolytic medication that prevents excessively rapid clot breakdown, may help prevent CSDH enlargement, potentially eliminating the need for repeat surgery. To evaluate the feasibility of conducting a trial investigating TXA efficacy in residual CSDH, we conducted an observer-blinded, pilot randomized controlled trial (RCT). We showed this trial was feasible and safe, reporting only minor to moderate AEs, and an attrition rate of 4%. The results from this study will inform the conduct of a double-blinded RCT investigating TXA efficacy in post-operative CSDH management.

Keywords: Chronic subdural hematoma
Randomized controlled trial
Tranexamic acid
Advisor: Cusimano, Michael D
Exploring Clinical and Biological Subtypes of Isocitrate Dehydrogenase Mutant Gliomas

Malignant gliomas are the most common primary brain tumours in adults. Due to their diffuse nature and significant inter- and intra-tumoural heterogeneity, conventional therapies fail to prolong patient life expectancy beyond 12-15 months upon diagnosis. Isocitrate dehydrogenase (IDH) mutations are critical early genetic alterations in glioma and confer a significantly improved prognosis. We sought to establish the importance of IDH mutations in glioma through three approaches. We show an overall support from the Neuro-Oncology field for the recent integration of IDH mutation in the World Health Organization diagnostic criteria for gliomas. Next, we report clinical utility in utilizing the oncometabolite, 2-hydroxyglutarate as a surrogate biomarker for IDH mutation detection. Lastly, we report distinct metabolic, clinical and epigenetic profiles in a cohort of IDH mutated lower grade gliomas, that “mimic” high grade glioblastoma. Our results support the clinical importance of IDH mutation and provide novel insights on its underlying biology.

Keywords: 2-hydroxyglutarate
Brain Cancer
Epigenetics
Glioma
Isocitrate Dehydrogenase
Metabolism
Advisor: Zadeh, Gelareh
What Matters to the Kids? Perspectives of Children with ASD on Weight and their Bodies

Introduction: Overweight and obesity (OW/OB) affects children with Autism Spectrum Disorder (ASD) at high rates, often compromising their health. Objective: To advance an understanding of OW/OB in relation to children with disabilities. Methods: 1. Applied a socioecological lens to examine risk factors for OW/OB for children with disabilities. 2. A scoping review of weight-management programs for children with disabilities. 3. Qualitative interviews with children with ASD. Results: Numerous actors beyond the individual child must be considered when supporting children with disabilities and OW/OB. While weight-management programs for this population are scarce, existing programs can be accommodated to include children with disabilities. Children with ASD were mostly unconcerned about their weight, view their bodies positively, and value being physically active. Discussion: Health care providers must critically examine their assumptions about weight. This work promotes shifting focus from weight and body size to health and growth to promote child- centered care.

Keywords: Autism Spectrum Disorder
Body Image
Disability
Health Care
Obesity
Weight Management
Advisor: McPherson, Amy C
Exploring the Needs of Cancer Survivors When Returning to or Staying in the Workforce

Cancer survivors have strong personal desires to resume work to feel productive and meet financial needs. However, they may be faced with physical and psychological challenges. This research aims to: examine cancer survivors’ perspectives on supports needed when returning to work; investigate sex and gender differences when returning to work; and explore demographic and employment factors that may influence this process. An exploratory qualitative design was used. The study had two phases: focus groups and one-on-one semi-structured interviews. Inductive thematic analysis was used to analyze the data. The total sample includes 15 participants, 87% female and 13% male. Key themes include: changing perspectives on self and work; managing work and social systems; determining disclosure and accommodation; and the importance of supports for return to work and daily life. This study informs cancer rehabilitation research by developing an understanding of the supports needed to help cancer survivors return to work successfully.

Keywords: Cancer
Rehabilitation
Return-to-work
Support
Advisor: Kirsh, Bonnie
Risk Stratification for Prevention of Venous Thromboembolism in Hospitalized Medical Patients: Can thromboprophylaxis be safely restricted to limit costs?

The objectives of this study were to estimate and compare the economic and clinical outcomes of using risk assessment models (RAMs) to support decision-making on thromboprophylaxis compared to the current standard of practice (SOP) in hospitalized medical patients at Sunnybrook Health Sciences Centre (SHSC). The Padua Prediction Score (PPS) and the Improve Risk Score (IRS), were applied to 199 general internal medicine (GIM) patients during three samples of one-week GIM admissions at SHSC. The predicted rate of hospital associated venous thromboembolism (HA-VTE) and the quality of life in GIM patients at SHSC identified as low risk of HA-VTE, was not significantly different after one year with RAM-directed thromboprophylaxis compared to SOP-directed thromboprophylaxis. Additionally, the use of RAMs had a significant potential annual cost savings of more than $200,000. Prospective evaluation is required to establish the feasibility and usability of RAMs and the safety of reducing the rate of thromboprophylaxis.

Keywords: Cost
Deep Vein Thrombosis
Medical Patients
Pulmonary Embolism
Risk Assessment Models
Venous Thromboembolism
Advisor: Walker, Scott E
Chemical Exchange Saturation Transfer MRI for Detection of Cell Death in Breast Cancer Xenografts

Detecting cell death after chemotherapy could help optimize treatment regimens and improve outcomes. Breast cancer xenografts (MDA-MB-231) were scanned before and after chemotherapy to investigate parameters of chemical exchange saturation transfer (CEST) MRI that can differentiate regions of cell death from viable tumour. The CEST effect at 0.5 μT saturation amplitude was measured using the magnetization transfer ratio (MTR) at 1.8 and -3.3 ppm frequency offsets. An MTR cutoff of 0.12 at 1.8 ppm was able differentiate between viable tumour and cell death regions (p

Keywords: Breast cancer
Cell death
CEST
Chemotherapy
MRI
Response monitoring
Advisor: Stanisz, Greg J
Czarnota, Gregory J
A Novel Evaluation of Alcohol Sensitivity in the Context of the Acquired Preparedness Model

The acquired preparedness model (APM) posits that the relationships between impulsivity and alcohol misuse are indirectly influenced through the biased acquisition of positive versus negative expectancies for the effects of alcohol. The present study assessed whether self-reported sensitivity to the lower dose/stimulant and heavier dose/sedative effects of alcohol would indirectly influence the impulsivity-expectancy relationship and drinking quantity and problems. Structural equation modeling was performed on cross-sectional, self-report data from 300 young adult heavy drinkers. Alcohol sensitivity was unrelated to impulsivity or alcohol expectancies, but each variable had unique associations with drinking outcomes, suggesting that alcohol sensitivity does not contribute to the APM. Lower alcohol sensitivity was directly associated with drinking outcomes. There were also positive, indirect effects in the traditional APM between impulsivity and drinking variables via positive and negative expectancies. Future research should try to replicate the model in a longitudinal sample to confirm temporal sequencing of relationships.

Keywords: acquired preparedness
alcohol
expectancy
impulsivity
learning theory
subjective response
Advisor: Hendershot, Christian S
Systematic Review – the Effectiveness, Efficacy and Safety of Giraffe OmniBeds

Extremely low birth weight (ELBW) preterm infants face many risk factors. The Giraffe OmniBed is a hybrid incubator-radiant warmer designed to treat complications of prematurity while minimizing environmental risks infants face when treated and transported using other interventions. Does the Giraffe OmniBed improve effectiveness, efficacy and safety outcomes for ELBW preterm infants? A systematic review of literature was conducted to answer the question. Two observational studies were identified for inclusion. While very low quality evidence suggests that the Giraffe OmniBed improves thermal stability, growth and skin maturity for ELBW preterm infants, it cannot be said, with confidence, until further research is done. Scarcity of evidence is a problem shared within the medical device industry, with the regulation of devices influencing evidence generation. Health care resources are finite. Informed decisions around the allocation of resources and thorough assessment of medical devices are crucial components of sustainable high quality healthcare.

Advisor: Coyte, Peter
Effects of final irrigation with CHX and EDTA based irrigant combined with detergents οn the surface of dentin using surface analytical methods

This study evaluated the formation of precipitate or parachloroanaline (PCA) on the root canal dentin surface after irrigation with NaOCl and final irrigation with Smear OFF using of Time-of-Flight Secondary-Ion-Mass-Spectrometry (TOF-SIMS) surface analysis and X- Ray Photoelectron spectroscopy (XPS). Dentin blocks from human maxillary molars were used and the dentinal tubules were exposed in a perpendicular orientation. The blocks were divided in CHX group: Irrigation with 6% NaOCl 17% EDTA 6 % NaOCl and 2% CHX, Smear OFF group: Irrigation with 6% NaOCl and Smear OFF. TOF – SIMS and XPS analysis of the blocks followed. Precipitation with PCA and occlusion of the dentinal tubules were noted on the surface of the dentin in the control group (CHX). No precipitate or PCA were detected on the surface of dentin in the experimental group (Smear OFF) and the dentinal tubules were open.

Keywords: chlorhexidine
parachloroanaline(PCA)
precipitate
sodium hypochlorite
TOF-SIMS
XPS
Advisor: Basrani, Bettina