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    Parent Anxiety and Child Psychopathology: A Longitudinal Study of Children with Physical Illness
    (University of Waterloo, 2026-02-03) Elgie, Melissa
    Estimates suggest that one in four children live with a chronic physical illness (CPI), such as arthritis, asthma, and diabetes. Children with CPI are vulnerable to developing psychopathology, known as multimorbidity. Approximately 40% of children with CPI experience multimorbidity, which is associated with lower self-esteem, poorer health-related quality of life, and a greater risk of substance use and suicidality. These negative outcomes may be a consequence of the substantial illness-related stress and uncertainty experienced by children with CPI and their families. To mitigate the compounding effects of child multimorbidity, it is essential to prioritize the health of these children by providing comprehensive, evidence-based healthcare services. However, doing so requires a deeper understanding of child multimorbidity, particularly in the family context. Beyond the affected child, parents of these children are likely to experience greater anxiety, resulting from managing CPI-related practical and emotional strains. This added stress and anxiety experienced by caregiving parents is posited to strengthen the association between parent and child mental health. Indeed, parent psychopathology has been identified as a key determinant of child multimorbidity; thus, efforts to improve the mental health of parents, in addition to the child, are paramount. Although there is consensus in the literature regarding the risk of children with CPI to developing multimorbidity, several knowledge gaps remain. Studies on child multimorbidity are predominantly illness specific, cross-sectional, and have short follow-up periods. Moreover, few studies have examined anxiety trajectories among parents of children with CPI, and the intersection between parent anxiety and child psychopathology. Although a handful of studies in non-clinical samples have explored associations between parent anxiety and child psychopathology, this knowledge is unlikely to generalize to the unique circumstances of childhood CPI. Accordingly, the aim of this dissertation was to obtain a more robust understanding of child multimorbidity, parent anxiety, and the complex association between parent anxiety and child psychopathology in this population. Opportunities to improve child and parent mental health via tailored, integrated, and family-centered approaches are emphasised. This dissertation is comprised of three distinct longitudinal studies which examined the onset of child multimorbidity, trajectories of parent anxiety, and the association between parent anxiety and psychopathology among children with CPI. Specific objectives were to: 1) evaluate child multimorbidity onset; 2) identify multimorbidity risk factors; 3) delineate trajectories of parent anxiety; 4) identify predictors of parent anxiety trajectories; 5) quantify the association between parent anxiety and child psychopathology; and 6) assess parenting stress and family functioning as moderators of this association. Data for this dissertation come from the Multimorbidity in Children and Youth across the Life-course (MY LIFE) study, a prospective cohort study of 263 children with CPI and their parents, who were followed for 48 months. The first study utilized survival analysis to determine that over the 48-month follow-up, 64% of children experienced multimorbidity (i.e., internalizing or externalizing psychopathology). Internalizing psychopathology was associated with greater child disability, older child age, and younger parent age, while the emergence of externalizing psychopathology was associated with male child sex and greater parent psychopathology symptoms. These findings suggest that a large proportion of children with CPI will develop multimorbidity and illustrates that multimorbidity onset is nuanced. Specifically, internalizing and externalizing psychopathologies were associated with distinct profiles of children. Findings highlight the importance of integrated physical and mental healthcare services to support the mental health of children with CPI. The second study examined the 48-month trajectories and predictors of parent anxiety symptoms using latent class growth modelling. Four trajectories of parent anxiety were identified: minimal, mild, moderate, and high. Approximately 40% of parents had persistent, moderate or high anxiety. Risk factors for less favourable anxiety trajectories were greater depression symptoms, higher educational attainment, having a female child, and having a child with multimorbidity. Results suggested that parents of children with CPI are at-risk of persistent anxiety, and parent- and child-related variables were associated with poorer anxiety trajectories. Because parents are responsible for the care of their children, promoting parental mental health is essential to ensure their well-being and that of their children. These findings garner support for greater refinement of pediatric healthcare services to be more family-centered and include strategies to promote the mental health of parents caring for children with CPI. The third study used linear mixed-effects modelling to examine associations between parent anxiety and child psychopathology. Results indicated that greater parenting anxiety was associated with greater child internalizing and externalizing symptoms over 48-months. Product-term interactions suggested that parenting stress and family functioning moderated the association between parent anxiety and child internalizing symptoms, while only family functioning moderated the association with externalizing symptoms. Results demonstrate the link between parent anxiety and child multimorbidity, and underscore the importance of evaluating parent anxiety, stress, and family functioning to support child mental health. These findings illustrate that to effectively manage the health of children with CPI, implementing evidence-based healthcare services which are family-centered must be prioritized. Knowledge from this dissertation addresses critical gaps in the understanding of child CPI, including multimorbidity onset, parent anxiety, and the association between parent anxiety and child psychopathology over time. Findings from this research reinforce that children with CPI and their parents face ongoing risk of psychopathology. Moreover, parent anxiety is associated with child multimorbidity, and family environmental factors likely influence this association. This research highlights five salient opportunities to refine pediatric healthcare: 1) early and routine mental health surveillance among children with CPI; 2) integrated physical and mental health services; 3) prioritizing family-centered care strategies; 4) targeted screening and interventions for at-risk subpopulations of children and parents; and 5) evidence-based interventions tailored to the unique experiences of children with CPI. Additional longitudinal studies are needed to explicate causal mechanisms which underpin the association between parent anxiety and child psychopathology, particularly among these vulnerable families. Providing comprehensive and integrated healthcare will help to reduce the incidence of multimorbidity and ensure the best possible outcomes for children with CPI and their parents.
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    Portus: Linking Alloy with SMT-based Finite Model Finding
    (IEEE, 2025-11-25) Dancy, Ryan; Day, Nancy A.; Zila, Owen; Tariq, Khadija; Poremba, Joseph
    Alloy is a well-known, formal, declarative language for modelling systems early in the software development process. Currently, it uses the Kodkod library as a back-end for finite model finding. Kodkod translates the model to a SAT problem; however, this method can often handle only problems of fairly low-size sets and is inherently finite. We present Portus, a method for translating Alloy into an equivalent many-sorted first-order logic problem (MSFOL). Once in MSFOL, the problem can be evaluated by an SMT-based finite model finding method implemented in the Fortress library, creating an alternative back-end for the Alloy Analyzer. Fortress converts the MSFOL finite model finding problem into the logic of uninterpreted functions with equality (EUF), a decidable fragment of first-order logic that is well-supported in many SMT solvers. We compare the performance of Portus with Kodkod on a corpus of 63 Alloy models written by experts. Our method is fully integrated into the Alloy Analyzer.
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    Real-Time Speed of Sound Estimation for Point-of-Care Tissue Health Assessment.
    (University of Waterloo, 2026-02-02) De la Torre Sanchez, Pat
    Speed-of-Sound (SoS) is a fundamental acoustic property that emerging Ultrasound (US) modalities aim to leverage for tissue health assessment and image quality improvement. Tissue SoS has been tied to tumor malignancy classification, muscle health assessment, steatotic liver classification and bone porosity measurement among other. Consequently, leveraging the tissue SoS for more accurate beamforming, not only enables higher resolution imaging, leading to more accurate cyst classification, but also correct for heavy skull aberration and defocusing during High Intensity Focused Ultrasound. Directly measuring the tissue SoS requires multi-site access, thus limiting such methods to the breast and some limbs. Current Pulse-echo SoS estimation algorithms demand high computation time or provide a single global SoS value, either constraining real-time assessment or decreasing accuracy. In this dissertation, I developed: 1) A single-shot SoS estimation algorithm that estimates the global SoS of the media by leveraging the signal consistency across channels from a single transmitting event. 2) Multiple localized SoS estimators that leverage image dissimilarity from multiple transmission events to provide the user with the SoS of the segmented regions in the image, either in stratified media, or arbitrary configurations. By developing custom image formation, segmentation, raytracing and wavefront tracking frameworks, optimal transmission schemes, and GPU acceleration on a portable, research scanner, I’m able to provide robust, accurate, SoS estimation platforms that have been thoroughly validated in vitro, ex vivo and in vivo. This dissertation research aims to bridge the gap between SoS research and other US modalities that can benefit from the SoS information, as well as the gap between the low-level-research side that develops methods for robust US tissue assessment, and the clinical research side that tracks and relates such features to conditions of clinical relevance. With the single-shot algorithm, I provide non-SoS researchers with valuable information to increase the accuracy of their algorithms without the need of long transmitting times or high computational demands, crucial for flow or real time imaging. With the other algorithms, I provide robust avenues for non-invasive tissue health assessment, as well as arming clinicians with access to intrinsic tissue features, that can be used for real time monitoring or for subsequent research that arise from the insights clinicians gain with this novel tool.
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    Psychosocial Outcomes of Youth with Chronic Physical Illness and Siblings
    (University of Waterloo, 2026-02-02) Basque, Dominique
    Youth with chronic physical illness (YwCPI) are more vulnerable to developing psychopathology than their healthy counterparts. Prospective studies show that psychopathology in youth remains stable over time and extends into adulthood. Ongoing symptoms, treatment, and worry about disease progression increase the risk for worsened mental health. Given that health status often impacts physical, mental, and psychosocial health outcomes, health-related quality of life (HRQL) has been a focus in health research. The functional limitations resulting from disability caused by chronic physical illness (CPI) disrupt school participation, peer support, and family relationships, contributing to lower HRQL compared to healthy peers. Existing research on CPI continuity and HRQL is constrained by infrequent assessments and disease-specific approaches, limiting understanding of psychosocial outcomes in YwCPI. CPI in youth also affects siblings. This is consistent with family systems theory, which posits that emotional functioning results from interactions between an individual and their family members, and the family unit and its contextual circumstances. Research finds that CPI negatively impacts sibling mental, physical, and psychosocial health. Siblings of YwCPI are also at higher risk for internalizing and externalizing symptoms compared to controls. However, studies on sibling mental health and HRQL are limited. Few studies use longitudinal methods, limiting the ability to assess the long-term impact of CPI. The aim of this research is to assess psychosocial outcomes in YwCPI and siblings. To address the aforementioned literature gaps, the objectives of this dissertation were to: 1) compare the homotypic and heterotypic continuity of psychopathology in YwCPI and siblings over 48 months, 2) model 48-month trajectories and assess predictors of HRQL in YwCPI and siblings, and 3) assess the mediating effect of sibling psychopathology on the association between YwCPI disability and sibling HRQL. Data come from the Multimorbidity in Children and Youth Across the Life Course Study; data were collected at baseline, 6, 12, 24, and 48 months. Study 1 utilized cross-lagged panel modelling to assess internalizing and externalizing symptom continuity in YwCPI and siblings. Auto-regressive pathways assessed homotypic continuity and cross-lagged pathways assessed heterotypic continuity. Separate models were computed for YwCPI and siblings. The method of variance estimates recovery (MOVER) assessed how patterns of continuity in YwCPI differed from siblings. Significant (p<0.05) autoregressive pathways were detected between all time points for internalizing and externalizing symptoms in YwCPI and siblings. Few cross-lagged paths were significant in either model. The MOVER showed no significant differences in the magnitude of any path estimates between YwCPI and siblings. Study 2 delineated trajectories of change for each domain of HRQL (physical well-being, psychological-being, autonomy and parent relations, peer and social support, school environment) using latent class growth analysis. Models were computed for YwCPI and siblings independently. Backward stepwise regression assessed predictors of trajectory group membership. The number of trajectory groups ranged from two to four, and class size ranged from 5% to 80%. Over half of the models included an increasing, no change, and decreasing group, with most changes occurring at earlier time points. The proportion of siblings having no change in HRQL was greater than YwCPI. Group membership predictors were age, income, and parenting stress. In Study 3, linear mixed-effect models assessed the mediating effect of sibling psychopathology on the association between YwCPI disability and sibling HRQL. YwCPI disability predicted increased sibling psychopathology, which was associated with lower sibling HRQL on all domains. Mediation effects were statistically significant in all models. Given the homotypic continuity of symptoms of psychopathology, health services should promote early and routine mental health screening for YwCPI and siblings. Early changes in YwCPI and sibling HRQL trajectories highlight critical opportunities for family-centred approaches to pediatric care. The mediating effect of sibling psychopathology in the association between YwCPI disability and sibling HRQL underscores the importance of integrating siblings into family-centred care, with targeted mental health screening and interventions that aim to mitigate negative psychosocial outcomes.
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    Navigating the Politics of Food System Futures: Post-Disaster Food Sovereignty in Puerto Rico
    (University of Waterloo, 2026-02-02) Diaz, Ileana
    Puerto Rico has been devastated by protracted economic collapse. Hurricanes Irma and Maria’s landfall in 2017 shattered the archipelago, followed by earthquakes in 2020, the COVID-19 pandemic, and Hurricane Fiona in 2022. There have been chronic issues with recovery post-disasters. In the context of economic, political, and ecological uncertainty, one of the most pressing concerns for Puerto Rico now and in the future will be its food supply. This research explores the effects of sequential disasters on the people of Puerto Rico and their food system. The study investigates food insecurity, government responses, and the will toward food sovereignty. The study is derived from individual in-depth interviews (n=84), archives (legal/court documents), media analysis (newspapers/photographs), and government data. The research adopts a critical and decolonial framework to the study of post-disaster Puerto Rico.