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Parent-child health behaviour patterns and adolescent weight : the moderating role of parenting styles
No full textBackground: Adolescent obesity is associated with multiple health behaviours within the family
context, including diet, physical activity, sedentary behaviour, and sleep. Parenting styles may
influence these behaviours, yet the combined effects of parent-child behavioural patterns and
parenting styles on adolescent weight outcomes remain understudied.
Objective: To examine how mother-child patterns of diet, physical activity, screen time, and sleep
behaviours are associated with adolescent zBMI, including the moderating role of parenting styles.
Methods: Data from 478 Grade 7 adolescents and their parents were collected for the HABITs
study (P.I. Dr. LC Mâsse) in Vancouver, British Columbia between 2019 and 2021. Participants
completed questionnaires about their health behaviours and adolescents reported on parental
demandingness and responsiveness. Latent class analysis was used to extract patterns of
behaviours. Multilinear regressions were used to model the relationship between behaviour
patterns and zBMI, and interaction terms were included to test for moderation effects. Exploratory
analyses on adolescent-only behaviour patterns were used to supplement the primary analyses.
Results: Neither mother-child nor adolescent-only behavioural patterns were significantly
associated with zBMI. However, a meaningful three-way interaction (p < 0.20) emerged for
adolescent-only behavioural groups between the healthiest group and the active + high screen
group. Adolescents in the active + high screen group had a zBMI on average 2.00 units higher than the healthiest group under neglectful parenting (low responsiveness and low demandingness; p =0.12) and 0.91 units higher under authoritative parenting (high demandingness × high responsiveness; p = 0.17). Though not statistically significant, these interactions suggest that parenting style may moderate how adolescent behaviours impact weight, potentially shifting weight classification from healthy to overweight or obese.
Conclusions: Findings indicate that parenting style may moderate the association between
adolescent behaviours and weight. Future research with larger and diverse samples is needed to
further examine these relationships. Understanding the interplay between family behaviour
patterns and parenting styles could inform tailored interventions to support healthier weight
trajectories in adolescents.Medicine, Faculty ofPopulation and Public Health (SPPH), School ofGraduat
Mind-reading too much or too little? : social-cognitive style & social anxiety among autistic young adults
No full textMany autistic people experience challenges with social cognition (i.e., understanding others’ thoughts, feelings, intentions). Social anxiety (particularly evaluation-related fears), which frequently co-occurs with autism, has been linked to excessively negative mental state attributions and “reading too much” into others’ thoughts and feelings among allistic (i.e., non-autistic) samples. By contrast, some autistic individuals experience non-evaluative social fears which may be partially explained by difficulties recognizing others’ mental states. How these varied social-cognitive biases (over- vs. undermentalizing, negative interpretation bias) relate to different forms of social anxiety in autism warrants investigation. This dissertation examined (1) how social anxiety relates to specific social-cognitive errors (overmentalizing, undermentalizing, total errors) on a naturalistic measure of social cognition in autistic young adults, and whether these associations are moderated by evaluation concerns; (2) whether the relationship between evaluative social fears and mentalizing errors is partially explained by negative interpretation bias; and (3) whether conceptual measures (cognitive mentalizing, emotion recognition) and self-reported mentalizing skills suggest a similar pattern of findings as naturalistic measures. Sixty-four autistic young adults completed a multimethod battery of experimental and self-report measures assessing multiple facets of social cognition, social anxiety (social fear/avoidance, evaluation-related fears), autistic traits, and cognitive functioning. Findings revealed distinct and opposing social-cognitive profiles among autistic young adults with greater evaluative fears, who were generally more accurate on conceptual mentalizing measures and had higher self-reported mentalizing skills yet tended to over-interpret others’ mental states on a naturalistic measure, and those with greater autistic traits, who were more likely to make inaccurate mental state interpretations on a naturalistic task due to missing social cues and had lower self-reported mentalizing skills. Autistic traits and social fear/avoidance were highly interrelated, each independently associated with less accurate social-cognitive skills, potentially reflecting a distinct presentation of non-evaluative social anxiety amongst autistic individuals. Findings extend the current understanding of mechanisms underlying social anxiety in autism, indicate a need for tailored interventions to address these distinct presentations of social fears and social-cognitive differences amongst autistic adults, and encourage future research examining how social experiences and coping strategies may interact with social-cognitive differences to contribute to social anxiety in autism.Arts, Faculty ofPsychology, Department ofGraduat
Sex differences in the neurophysiological and ventilatory responses to exercise : impact on the sensations of exertional dyspnea
No full textPurpose: This dissertation comprised three studies that examined the physiological, neurophysiological, and psychosocial mechanisms underlying sex differences in the multidimensional experience of exertional dyspnea.
Methods: Study #1 (chapter 2) compared physiological, perceptual, and psychosocial factors between males and females who did versus did not select unsatisfied inspiration at peak exercise. Study #2 (chapter 3) investigated the effects of added ventilatory loading (dead space customized to 15 % of forced vital capacity) on sex differences in respiratory mechanics, neurophysiological responses, and the multidimensional components of exertional dyspnea. Study #3 (chapter 4) evaluated how relative dead space loading influenced respiratory muscle activation patterns and pressure generation in males and females. All studies used maximal incremental cycling exercise.
Conclusions: We found that smaller absolute lung volumes were associated with higher intensity ratings of unsatisfied inspiration during exercise, and psychosocial factors, such as gender and anxiety, emerged as important contributors to sex differences in dyspnea perception (chapter 2). Although males and females exhibited distinct cardiorespiratory, respiratory mechanical, and neurophysiological responses, as well as respiratory muscle activation patterns with added dead space loading, these differences did not consistently translate to altered dyspnea perception during maximal cycling (chapters 3-4). Collectively, these findings suggest that despite well-established sex differences in respiratory anatomy and physiology, males and females appear to employ distinct reflexive respiratory muscle activation patterns that result in comparable perceptions of exertional dyspnea. Collectively, this work emphasizes that exertional dyspnea cannot be attributed to a single mechanism but instead reflects the complex interplay of anatomical, physiological, and psychosocial factors. Recognizing the reflexive respiratory muscle activation patterns in males and females may guide future research aimed at refining clinical assessment and developing more personalized approaches to managing dyspnea in aging populations and patient groups.Medicine, Faculty ofMedicine, Department ofOccupational Science and Occupational Therapy, Department ofPhysical Therapy, Department ofGraduat
Inferring persistent molecular changes in former smokers' airways associated with lung cancer
No full textFormer heavy tobacco smokers remain at high risk for lung cancer long after they quit smoking. Smoking induces a field of injury in airways, which can be detected as persistent changes in gene expression and epigenetic marks in airway epithelial cells. While most of these changes revert to normal levels after smoking cessation, some changes persist in former smokers for many years. If these changes are shown to contribute to lung cancer tumorigenesis, they could be intercepted before lesions form, used to stratify former smokers by cancer risk for screening programs, or detected in a non-invasive manner. Existing studies have not fully characterized the mechanisms underlying the airway field of injury and how they are linked to lung cancer. We incorporate data from multiple studies to infer genes with persistently altered RNA expression in former smoker airways, mechanisms potentially underlying this persistence, and potential interpretations of the expression changes. We determine which of these expression changes could be linked to lung cancer by performing comparisons with lung cancer ‘omics datasets. We utilize meta-analysis to corroborate the genes’ link to smoking in airways, and exploratory analyses to assess potential mechanisms and biological relevance. To summarize, we have established sets of genes that could link the persistent airway field of injury to lung cancer and explored putative related mechanisms.Medicine, Faculty ofGraduat
Building capacity for a palliative approach to care for people with chronic, life-limiting conditions in the primary care context
No full textA growing number of Canadian adults are living with chronic, life-limiting conditions such as organ disease, neurological or cognitive impairment, and frailty that impact their quality of life and death. Most Canadians are likely to need palliative care due to chronic conditions but few receive it outside of hospitals, often in the final days or weeks of life, or not at all. Within the literature, a palliative approach to care is increasingly being recognized as an exemplary approach to patient-centred chronic care. A palliative approach blends chronic illness management and palliative care principles to address a person’s care needs early and throughout the trajectory of a chronic condition and has been associated with better quality of life and death. Best practices suggest primary care could be an exemplary environment where a palliative approach is integrated ‘upstream’ and then followed throughout the course of their condition. Despite the evidence showing considerable benefits, several barriers to integrating this type of care approach routinely into primary care remain.
Interpretive Description was employed as the methodological framework to better understand how to overcome barriers and build greater capacity for a palliative approach to care in a primary care context for this population. Twenty-six individual interviews were conducted and inductively analyzed to generate new knowledge and practical insight from practitioners and stakeholders with expertise using a palliative approach in a variety of locations in British Columbia, Canada. Participants identified practice and system level changes that could help overcome existing barriers and inspire primary care providers to integrate a palliative approach into practice. Suggestions include a team or shared-care approach, peer mentorship and support, better utilization of primary care nurses and nurse practitioners, and a stronger investment at practice and system levels. Practice implications include a more precise understanding of a palliative approach to care, greater equity and consistency across provincial healthcare structures and supports, and replicating practice models that have been shown to work. Areas for further research include exploring barriers and facilitators to integrating a palliative approach from patient and caregiver perspectives and active engagement of nurses as knowledge users to enable change.Applied Science, Faculty ofNursing, School ofGraduat
Validation of cellular barcoding enabled clonal tracking in Barrett's esophagus stem cell populations
No full textEsophageal adenocarcinoma (EAC) is one of the deadliest cancers, with a five-year net survival rate of only 16% according to the Canadian Cancer Society. A key factor contributing to its high mortality is late-stage diagnosis. Barrett’s Esophagus (BE), an intestinal-type metaplasia arising in the distal esophagus in response to chronic inflammation, is a precursor lesion for EAC. Although the overall risk of progression from BE to EAC is low, it increases significantly following the development of high-grade dysplasia (HGD), a genetically unstable, precancerous dysplastic state. Currently, the detection of BE relies on endoscopic surveillance and histological assessment, and predicting which patients will progress to HGD before the phenotypic switch takes place is not possible. Beyond the classical oncogenic mutations (i.e. TP53, CDKN2A) which often precede catastrophic genomic events that drive progression, the genetic mutations that may initiate BE progression but are lost through to dysplasia, remain poorly characterized. The field of carcinogenesis is lacking a method by which to track clonal competition of BE stem cells in real time to identify potentially malignant clones before they drive phenotypic shifts.
This project aims to develop and validate a method to uncover the clonal competition that drives clonal expansion of malignant clones in BE. To achieve this, we adapted a previously established DNA barcoding technology for use in our adult tissue resident stem cell (ASC) populations to track clonal competition in real time. To validate this tool’s ability to detect clones with a selective growth advantage, we introduced a faster-growing cell line carrying a known barcode sequence into a barcoded population of BE-ASCs. The faster-growing cell line could be informatically recovered, and sequencing data revealed clonal competition within BE-ASC populations, establishing an empirical basis to further explore the capability of this methodology to identify potentially malignant BE clones. This approach has the potential to identify previously unknown causative genes involved in BE progression, as well as improve early detection, and risk assessments of EAC; ultimately enabling the development of less invasive, cost-effective screening strategies for BE and improving the ability to detect high-risk individuals before the progression to cancer.Medicine, Faculty ofMedicine, Department ofGraduat
Public transit electrification planning with energy storage via second-life batteries : a stochastic programming approach
No full textAs part of decarbonization strategies, public transit systems are aiming to electrify their fleets in response to climate targets and net-zero goals. However, the resulting increase in electricity demand may lead to energy stress on the electrical grid. Second-life batteries (SLBs) offer a potential solution, yet their financial, energy, and environmental impacts remain underexplored, as does the long-term planning for their integration. This study proposes a strategic planning model for transitioning a public transit fleet to battery electric buses (BEBs), incorporating the deployment of SLBs as a battery energy storage system (BESS). The model jointly optimizes decisions on asset procurement, replacement, route-level fleet assignments, the integration of SLBs as BESS, and the installation of a supporting renewable energy system (RES). A multi-period stochastic programming framework is employed to optimize planning under uncertainties, such as vehicle and battery costs, and the model is formulated as a mixed-integer linear program. A case study of Metro Vancouver’s transit system is conducted to evaluate three electrification pathways. Results show that SLBs can meet up to 84% of the fleet’s recharging energy demand, reduce annual operating costs by up to 78 million. Spatial constraints on SLB deployment, layout design, and BESS fixed costs may increase the total cost, despite potential savings from BESS operations. Policy incentives to utilize SLBs and reduce BESS installation costs, such as BC Hydro's energy storage incentive, play an important role in the economic viability of the approach. A sensitivity analysis of battery and electricity prices provides insights into the integration of SLBs under different market and policy conditions, with environmental benefits evident for jurisdictions where electricity is produced by non-renewable sources.Applied Science, Faculty ofMechanical Engineering, Department ofGraduat
Genetic mechanisms and fitness consequences of rapid evolution in severe and complex metal-contaminated environments: evolutionary rescue of Saccharomyces cerevisiae
No full textA population’s ability to escape extinction and persist following catastrophic environmental change depends on the fixation of rare alleles that improve fitness in the new environment. The rare individuals bearing these alleles survive, reproduce, and rescue the population from extinction. What types of mutations underlie this phenomenon, "evolutionary rescue", and how do they affect resistance to other stressors? Evolutionary rescue becomes more complicated when multiple stressors interact and modify the harshness of the environment in unexpected ways. Combined stressors can be more deadly (synergistic), less deadly (antagonistic), or equal to the sum of the isolated stressors’ effects. When the effect of a stressor combination deviates from concentration-addition models (i.e., when interactions occur), how are the genetic mechanisms and fitness outcomes of evolutionary rescue affected? I investigate these questions by exposing Saccharomyces cerevisiae to various concentrations of six metals (Cd, Co, Cu, Mn, Ni, and Zn) and their 15 binary combinations. First, I performed evolutionary rescue experiments in each single metal and measured cross-tolerance of evolved lines to the other metals. Whole-genome sequencing revealed that lines with broader cross-tolerance often carried mutations impacting phosphate metabolism. Next, I quantified the combined effects of the metal pairs using two metrics: a previously established interaction value, a, describing deviation from a null model of additivity, and a new metric, δ, describing how harmful a combination is relative to the average of its components. I observed a wide range of interactions, with manganese involved in antagonistic combinations and copper involved in synergistic ones. Finally, I performed evolutionary rescue experiments in the metal pairs, generating evolved lines in eight of the 15 combinations. Evolutionary rescue in antagonistic metal combinations tended to confer fitness benefits in each individual metal, while synergistic combinations favoured mutations with more specific benefits to the pair’s combined effect. By linking evolved fitness patterns to molecular mechanisms, this work advances understanding of evolutionary rescue under multiple metal stresses, an important step toward predicting and managing populations at risk of extinction in an increasingly human-altered world.Science, Faculty ofZoology, Department ofGraduat
Molten salt strategies for preparation of biocarbon towards advanced pore structure and supercapacitor applications
No full textPore structure engineering remains a critical challenge in the development of high-performance biocarbon materials, particularly for supercapacitor applications where an optimal balance of high specific surface area (SSA), tunable pore size distribution (PSD), and interconnected micro–mesoporous network is essential for effective ion adsorption and diffusion. Conventional activation methods, such as KOH or H₃PO₄ treatment, often suffer from poor control over PSD, high energy consumption, excessive chemical usage, and reliance on trial-and-error experimental design, limiting their tunability, scalability, and sustainability. This thesis introduces a systematic binary molten salt carbonization strategy to enhance and control the pore structure of biocarbon derived from chitin, an underutilized biomass waste. A novel ZnCl₂–CaCl₂ binary molten salt system is developed to achieve biocarbon with a hierarchical porous structure, high SSA (1671 m² g⁻¹), and rich heteroatom retention at 800 °C. These two salts show synergistic effects on enhancing SSA but play distinctively different roles in facilitating micropore and mesopore formation. Subsequently, a general strategy for binary molten salt selection is developed based on the understanding of salt accessibility and reactivity. CuCl₂ and ZnCl₂ serve as suitable primary salts and combined with various secondary salts such as CoCl₂ and CaCl₂ to fine-tune micropore-mesopore structure under different operating conditions. Notably, a ZnCl₂–CoCl₂ system achieved ultrahigh SSA (~2500 m² g⁻¹) at only 500 °C, and further guidance on secondary salt selection for pore tuning in ZnCl₂-based salt systems is proposed for low-temperature activation based on the mechanistic understanding of the roles of salt diffusion, transition and interactions with chitin for primary and secondary salts in controlling pore creation and development. Finally, the electrochemical characterization of fabricated biocarbon electrodes confirm excellent supercapacitor performance, including high specific capacitance, rate capability and long-term cyclic stability. Multivariable regression further quantitatively clarifies the contributions of micropore volume and mesopore fraction to specific capacitance and rate capability. Overall, this work offers a systematic and guided approach for tunable pore structure engineering in biocarbon, advancing the design of high-performance biocarbon for supercapacitors and adsorption-related applications (e.g., CO₂ capture). It marks a step forward from conventional and empirical fabrication methods towards organized and mechanism-driven process and material design.Applied Science, Faculty ofChemical and Biological Engineering, Department ofGraduat
Investigating unmet need for clinical genetic services in Canada
No full textGenetic counselling and genetic testing can have many positive outcomes for patients and families. Despite the benefits, there is unmet need for clinical genetic services amongst Canadians. The aims of this research were to characterize the top of scope of genetic counselling practice, estimate the prevalence and distribution of unmet need for genetic counselling, and explore public perspectives about unmet need for genetic testing. This research involved a multi-methods approach including a scoping review, survey, and interviews. Data collection approaches included a systematic literature search (148 included papers), a cross-sectional survey distributed through a market research company (n=1289), and semi-structured one-on-one virtual interviews (n=19). Data analysis occurred through narrative synthesis for the scoping review, survey data was analyzed using descriptive statistics, univariate analysis, and a stepwise multivariable regression analysis, and qualitative analysis was conducted using interpretive description and reflexive thematic analysis. Top of scope genetic counselling practice can be described as a psychologically-oriented process, however, there are variations in the evidence about the goals, processes, outcomes, theories, models, and frameworks of genetic counselling practice. Through this understanding of top of scope of genetic counselling practice, it was found that up to 39% of Canadians may have unmet need for genetic counselling and that it was more likely in younger individuals, those with mental health concerns, individuals with lower levels of capability, and those with higher perceived utility. In the interviews, participants self-reported need for genetic testing was shaped by their past experiences with genetic information and their beliefs about its usefulness, both in terms of clinical actionability (clinical utility) and personal significance (personal utility). Although most participants did not meet the eligibility criteria for publicly funded testing based on their personal and family history, they still had unaddressed informational and psychological needs. Unmet expectations about genetic testing contributed to a sense of dissatisfaction and distrust among the public. There is unmet need for genetic counselling and genetic testing in Canada that is unlikely to be met through current service delivery and more efforts are needed to increase equitable access to genetics healthcare.Graduate and Postdoctoral StudiesGraduat