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Degradation and Failure Analysis of Environmental Barrier Coatings under Adverse Operating Environment: Multi-Physics Modelling
No full textEnvironmental barrier coatings (EBCs) are essential for protecting ceramic matrix composite (CMC) substrates in advanced gas turbines and aero-engines. However, their durability is limited by thermo-mechanical stresses, oxidation, and water-vapor-induced degradation under high-temperature operating conditions. The premature failure of EBCs, particularly delamination along the interfaces of thermally grown oxide (TGO) poses major challenges to coating reliability. This research presents a systematic study of the degradation of bi-layer Yb₂Si₂O₇/Si EBCs using COMSOL Multiphysics methodologies. Thermal cycle-induced temperature fields were implemented into the EBC model, aiming to simulate the system's in-service conditions. Coupled thermo-mechanical processes were simulated, incorporating high-temperature creep behavior, phase transformation from Yb₂Si₂O₇ to Yb₂SiO₅, and TGO growth kinetics. The model also accounted for the β-α phase transformation of cristobalite TGO between 220°C and 270°C, which introduces significant volumetric changes during cooling. Based on the evaluated local stress evolution and distribution in the EBC system during thermal cycles in water-vapor environments, the experimentally observed EBC degradation mode was explained in terms of the simulated results. Fracture behavior was investigated using J-integral, Virtual Crack Extension, and a phase-field damage model to capture crack initiation and propagation within the coating system. The results show that large tensile stresses in the TGO promote spontaneous crack formation, which can bifurcate and propagate along Yb₂Si₂O₇/TGO and Si/TGO interfaces. Coalescence of these bifurcation-induced delamination cracks could be the primary mechanism leading to the EBC's spallation and failure. The simulated TGO crack growth pattern was compared with that experimentally observed in the literature. Additionally, the effect of interface morphology on crack evolution was systematically investigated. Increasing interface undulation was found to intensify local stress concentrations, enhance mixed-mode fracture driving forces, and accelerate interfacial delamination. The findings of this study enhance the understanding of EBC degradation and provides an integrated multi-physics framework for predicting failure
Critical Conversations in Canadian Public Law
No full textCritical Conversations in Canadian Public Law is a groundbreaking open-access collection of peer-reviewed essays showcasing interdisciplinary thinking on topical public law issues at the forefront of the evolving relationship between state and society.
In Canada, this relationship is undergoing a period of significant reinvention, as evidenced, for example, by the movements for reconciliation, decolonization and Indigenization, the calls to recognize and remedy systemic racism in institutions including police forces, and the recent extension of human rights protections to prohibit discrimination based on gender identity or expression.
These examples reveal that we are experiencing a moment where claims that challenge the normative foundations of the discipline of public law are being made in real time; claims about citizenship, rights, and access to resources and benefits; claims about what substantive and procedural fairness look like, and for whom; claims about the obligations and limits of the state to proactively address both historical and current injustices; and challenges to the underlying assumptions about the state itself.
Critical Conversations in Canadian Public Law highlights the intersections of critical perspectives–including intersectional approaches to decolonial and Indigenous legal theory, Indigenous constitutionalisms, critical race theory, feminisms, queer theory and critical disability theory–and public law topics, broadly defined.
This collection bridges the divide between traditional, largely liberal, public law scholarship and critical perspectives by centring critical theories as not only relevant, but imperative, to robust, fully contextualized understandings of contemporary public law challenges.List of Figures
Acknowledgements
Introduction
Joshua Sealy-Harrington, Karen Drake, Kyle Kirkup, Anne Levesque, and Jena McGill
Section A: Indigenous Peoples and Critical Approaches to Canadian Law
Chapter A-1
Critical Theory and Crown-Indigenous Relations
Gordon Christie
Chapter A-2
Indigenous Rights and Responsibilities to Language Transmission: Implementing Article 14 of UNDRIP
Lorena Sekwan Fontaine
Chapter A-3
Critical Approaches to Jurisdiction: The Struggle for Control of Indigenous Lands and Resources
Dayna Nadine Scott
Chapter A-4
Four Views of Métis Constitutionalism
Kerry Sloan
Chapter A-5
Wanted: Indigenous Representation on the Supreme Court of Canada (But the Indian in the Child Must Be Gone!)
Harry S. LaForme
Section B: Policing, Criminal Law, and the Carceral State
Chapter B-1
Is Gladue Sentencing Exceptional?
Lisa Kerr
Chapter B-2
Abolitionist Lawyers: Making Prisons Obsolete
Reakash Walters
Chapter B-3
Être puni·e sans nécessairement être condamné·e : la punitivité avant procès et au-delà de la matière criminelle en droit canadien
Véronique Fortin et João Velloso
Chapter B-4
The Hunt for Red October: Critical Race Theory and Racial McCarthyism
Vincent Wong
Chapter B-5
The School Policing Origins of R v Grant
Lisa M. Kelly
Chapter B-6
An Open Letter to Legal Workers: Imagining a World Beyond Civilian Oversight of Policing
Meenakshi Mannoe
Section C: Boundaries and Borders of Public Law
Chapter C-1
The Xenophobic Gap in the Charter’s Equality Guarantee
Y. Y. Brandon Chen
Chapter C-2
Disruptive Choices: Agency, Religious Freedom, and Veiling Muslim Women in Canadian Constitutional Law
Ashleigh Keall
Chapter C-3
Pour une application de la Charte fondée sur les droits de l’enfant
Mona Paré
Chapter C-4
Critical Disability Theory and Public Law in Canada: The Case of Longueépée v University of Waterloo
Ravi Malhotra
Chapter C-5
Critical Perspectives in Canadian Tax Law
Samuel Singer and Allison Christians
Biographie
Secretogranin-2 Complete Gene Knockouts in Zebrafish Reveal Their Stimulatory Roles in Female Reproduction
No full textSecretogranin-2 (Scg2) is a precursor protein in secretory vesicles of neuroendocrine neurons and pituitary hormone-secreting cells. Enzyme processing of Scg2 yields the bioactive peptide secretoneurin (SN) and others. Evidence links SN to reproductive control, enhancing gonadotroph function in several species. We employed CRISPR-Cas9 to excise both the scg2a and scg2b genes and generate single and double knockout (DKO) zebrafish. To confirm the success of gene deletion, the knockout lines were rigorously validated through sequencing, peptide mass spectrometry and immunohistochemistry. The scg2a-/- and scg2b-/- lines were crossed to establish a DKO model to investigate the role of the scg2 genes in zebrafish reproduction. Morphometric assessments indicated that scg2b-/- and DKO females had increased weight but shorter body lengths. Behavioural analysis showed reduced quiver behaviour in male scg2a-/- and scg2b-/- fish, while significant delays in oviposition were observed for females in the scg2b-/- and DKO groups. Lower spawning rates were recorded for within-line crosses of scg2a-/-, scg2b-/- single KO, and DKO fish (28%, 24%, and 16.6%) compared to WT (64.5%), and all KO groups exhibited low fecundity. The unspawned DKO females could not spawn with WT males, evidencing female-specific spawning defects. Ovarian histology revealed a reduction in mature oocytes and increased atresia in the DKO ovary. The injection of synthetic SNa, SNb, or human chorionic gonadotropin did not restore spawning, highlighting severe reproductive dysfunction in DKO females. Molecular analysis using digital PCR for genes encoding neuropeptides and gonadotropins indicated that, at pre-ovulation, DKO females exhibited decreased gnrh3 and increased avp levels in the hypothalamus, along with upregulated pituitary lhb and fshb, and downregulated gnrhr2. Expression of oxt was significantly reduced in both telencephalon and hypothalamus during ovulation, whereas avp was highly expressed only in the hypothalamus. Additionally, during ovulation, gnrhr2 and cga were downregulated in the pituitary, while lhb and fshb levels remained elevated. Post-ovulation, oxt in the telencephalon was consistently downregulated, and levels of hypothalamic gnrh2, avp, and pituitary cga were also reduced compared to WT. Ovarian lhcgr and star1 expression showed significant reduction throughout the ovulation cycle, indicating impaired hormonal signalling and disrupted reproductive regulation in the HPG axis. The shape of the pituitary in DKO fish was altered, having an abnormal elongated shape compared to the teardrop-like oval shape in the WT pituitary. Single-pituitary proteomics identified 3674 proteins and revealed 51 significantly altered proteins between DKO and WT, indicating a major shift in pituitary function. These results demonstrate that scg2a and scg2b are crucial for reproduction in zebrafish, impacting spawning, oviposition timing, fecundity, oocyte maturation, and the regulation of reproductive hormones in the HPG axis. The secretograninergic system is, therefore, important for the regulation of fertility
Trésors d'archives, épisode 2 : « Emma-Adèle Bourgeois Lacerte, Roxane et les Éditions Édouard Garand »
No full text« Trésors d’archives » est un balado de la Bibliothèque de l’Université d’Ottawa mettant valeur différents documents en français tirés de ses Archives et collections spéciales. Découvrez des objets rares, précieux ou inusités en compagnie d’archivistes et de spécialistes! Ces chercheurs et chercheuses explorent la matérialité, le contexte historique et l'impact culturel de ces documents, et nous expliquent comment ces archives appuient la recherche de pointe en français à l’Université d’Ottawa.
Emma-Adèle Bourgeois Lacerte – ou Mme A. B. Lacerte de son nom de plume – était une autrice francophone d’Ottawa, vedette des Éditions Édouard Garand, l’un des premiers éditeurs de masse au Québec. En plus de connaître un important succès commercial, les Éditions Édouard Garand ont publié de nombreuses autrices, ainsi que plusieurs auteurs issus de la francophonie canadienne.
Dans cet épisode de « Trésors d’archives », nous explorons la littérature populaire canadienne-française des années 1920 – bien différente de littérature du terroir! – à l’aide de « Roxane », un roman d’aventures sentimental de Mme A. B. Lacerte, conservé dans la remarquable collection de brochures des Archives et collections spéciales de la Bibliothèque.
Invitées : Marie Noël, archiviste à la Bibliothèque de l’Université d’Ottawa et Lucie Hotte, chercheuse émérite au Centre de recherche sur les francophonies canadiennes (CRCCF) et professeure émérite au Département de français de l’Université d’Ottawa.Le balado « Trésors d’archives » est présenté dans le cadre de l’Entente Canada-Ontario relative à l’enseignement dans la langue de la minorité et à l’enseignement de la seconde langue officielle
Intranasal Administration of Highly Conserved Influenza Antigens to Elicit Local Mucosal Responses and Enhance Cross-Subtype Protection
No full textInfluenza causes approximately 650,000 deaths worldwide each year and remains one of the top ten causes of death in Canada. The public health burden of influenza is exacerbated by the highly variable year-to-year effectiveness of licensed vaccines. The unpredictable evolution of influenza surface antigens often leads to a mismatch between the circulating strain and the predicted vaccine strain. Additionally, current vaccines have limited ability to prevent early viral replication in the upper respiratory tract. Alternative strategies are needed to address these limitations in current influenza vaccines.
This thesis investigates the intranasal (IN) administration of conserved influenza antigens as a strategy to enhance heterosubtypic protection. By characterizing both systemic and mucosal immune responses elicited by this approach, I aim to advance our understanding of immunity against influenza viruses and to provide insights for the design of next-generation vaccines.
My research compared the protective mechanisms of intramuscular (IM) and IN delivery of a recombinant adenovirus encoding the highly conserved influenza nucleoprotein (NP), adjuvanted through fusion to CD40 ligand. While IM administration more effectively induced systemic cellular immune responses, IN immunization conferred superior cross-subtype protection through robust mucosal antibody production and pulmonary T cell responses. This thesis also evaluated the protective efficacy and immune responses elicited by an IN vaccine designed to express the consensus sequence of hemagglutinin subunit 2 (HA2) derived from all H3 strains. This approach provided cross-subtype protection against lethal H3N2 and H7N9 challenges. Further immunological analysis revealed that the vaccine induced antigen-specific pulmonary cellular and humoral immunity. Notably, a C-terminal region of the HA2 consensus sequence was identified to contain immunodominant epitopes, capable of inducing potent CD4+ and CD8+ T cell responses.
In conclusion, these studies provide mechanistic insights into the protective immune responses induced by IN administered vaccines targeting conserved influenza antigens. These findings contribute to the development of next-generation mucosal vaccines against a broad range of emerging respiratory viral pathogens
Family Dynamics and the Developing Child: The Influence of Parenting Behaviours and Family Functioning on Self-Harm and Suicidality in Childhood and Adolescence
No full textAdolescent self-harm is a global public health problem. Suicide is a leading cause of death among adolescents aged 15-19 years, and self-harming thoughts and behaviours are risk factors for suicide. The family environment and associated experiences are recognized as a social determinant of health, affecting the developing child in a myriad of ways, including their mental health. Family dynamics directly teach the child how they must adapt and interact with the world. Ultimately, how a family functions and the parenting practices they rely on influence the child's socioemotional development.
What is not understood is whether family dynamics confer prospective risk or protective effects on the onset of self-harming thoughts and behaviours in childhood and adolescence. Similarly, it is unclear whether these risk or protective effects are causal. Among adolescents who develop self-harming thoughts or behaviours, many do not seek support, not at least until professional mental health care may be urgently required. It has yet to be determined whether family dynamics may promote or hinder support-seeking behaviours among adolescents who experience self-harming thoughts or behaviours. The overall objective of this body of doctoral work was to address these key knowledge gaps to inform clinical practice and, more long-term, upstream suicide prevention efforts.
By summarizing the prospective literature base (study 1), we found that negative family dynamics of family dysfunction and negative parenting practices longitudinally predict self-harm and suicidality (suicidal ideation and attempt) in childhood and adolescence. In study 2, we employed causal inference methods (i.e., marginal structural models) to estimate the effect of negative parenting practices (harsh and withdrawal methods) on self-harm in adolescence. Both forms of negative parenting practices led to the onset and maintenance of non-suicidal self-harm in adolescence. In the last study (study 3), we demonstrated that cross-sectionally and among adolescents experiencing suicidal ideation, negative family dynamics are a barrier to help-seeking from family and may lead the adolescent to seek support elsewhere (i.e., online).
The findings of this doctoral work highlight the importance of family dynamics on the mental health of the developing child. We provide several clinical and public health recommendations, including addressing family dynamics among children and adolescents presenting with self-harming thoughts or behaviours, and formally recognizing family dynamics as a risk and protective factor in suicide prevention efforts
Intimate Partner Violence Experiences of Middle Eastern Immigrant Women Living in Ottawa During the Perinatal Period
No full textBackground: Intimate partner violence (IPV) during the perinatal period is a significant problem for Middle Eastern immigrant women (MEIW) and requires comprehensive and culturally responsive interventions that address the underlying risk factors. Several risk factors (e.g., cultural norms, the perinatal period and language barriers) contribute to increasing women's vulnerability to IPV. Additionally, MEIW face multiple forces of oppression such as racism which are further intersected by factors associated with their immigrant status, creating a unique IPV experience that calls for a systematic investigation. However, there is limited research in this area, a critical gap in knowledge and practice which this study addresses. This study explored the experiences of IPV among MEIW living in Ottawa during the perinatal period.
Theoretical Framework: This study was guided by the Intersectionality lens and the Socio-Ecological Model to explore the intersections of gender and other factors as well as the multiple layers of issues associated with IPV.
Methodology: The study has two phases: phase 1, a scoping review of studies examining IPV within the context of MEIW during the perinatal period, and phase 2, an instrumental case study guided by Stake's (1995) approach to qualitative case study research. As part of Phase 2, research ethics approval was obtained from the Research Ethics Board prior to participant recruitment. Following approval, MEIW during the perinatal period were recruited using convenience and purposeful sampling techniques. Data collection involved in-depth individual interviews with 20 participants and one focus group discussion. The interviews were audio-recorded, transcribed verbatim and analyzed thematically as described by Braun and Clarke (2006). The FGD served as member-checking to establish the credibility of the data.
Results: Findings reveal that IPV among MEIW is not just an individual experience, but a socially embedded phenomenon influenced by patriarchal norms and systemic inequities. Five major themes were identified, 1. Defining IPV, 2. Forms of IPV, 3. IPV impact, 4. IPV vulnerabilities and help seeking behaviours, and 5. IPV coping strategies.
Discussion and Implications: It synthesizes four overarching themes, underscoring the need for culturally responsive interventions that more effectively support MEIW experiencing IPV.
Conclusion: This study deepens our understanding of IPV during the perinatal period for MEIW, providing insight into how cultural and systemic factors influence their experiences. The findings call for culturally responsive interventions and policies that consider the complex realities of IPV in Middle Eastern immigrant communities
The Growth of Relic and Icon Veneration in the Eastern Roman Empire During the Reigns of Justinian and His Successors (527-602) and Their Impact on the Hyper-Sacralisation of Imperial Power
No full textAbstract
The evolution of the cultural and political landscapes of the eastern Roman empire during the sixth century presents many challenges for scholars. The emperor Justinian and his successors reigned during a dynamic and turbulent period of cultural and political change. For two centuries, Christianity had taken shape within the eastern Roman empire by developing its own traditions. By the end of the sixth century, Christianity encompassed all aspects of eastern Roman society. It impacted the cultural and political landscape in which the emperors of the Justinianic dynasty displayed their imperial authority and promoted their ideologies. Yet classical culture and mentalities had not disappeared. In fact, at times, antiquarian or classical mentalities informed Christian innovations and were often integrated within the new Christian landscape. By the sixth century, however, the continuation of the classical tradition had the potential to create tensions within the Christianising empire. We are thus left at a crossroads between two seemingly contradictory traditions during a period of cultural and political transition. This is the cultural background that shaped the imperial ideologies of the emperor Justinian and his successors.
This thesis brings together in one coherent study three widely debated topics in academia and sheds new light on the impact of Christianity on the cultural and political evolution of the eastern Roman empire during the reigns of the emperors of the Justinianic dynasty. The primary concern of this thesis is the integration of Christianity within the imperial ideologies of the emperor Justinian and his successors at the same time as they tried to promote Roman imperial renewal or restoration during a period of transition. Previous scholarly contributions paved the way for further research of the topic at hand and several approaches have been presented in academia, but the nature of this evolution remains obscure. This thesis offers a different approach by combining three ongoing debated topics, namely the rise and growth of relic and icon veneration in Late Antiquity, the hyper-sacralisation of imperial power, and the Christianisation of eastern Roman society during the sixth century. By examining the primary Greek, Latin and Syriac sources, this thesis argues that Christian cults of veneration, namely those of the saints, their relics and icons, impacted the cultural and political evolution of the sixth century, particularly in regard to imperial ideologies
Trajectoires de politisation de Métis du Manitoba : entre mémoire, relation et identité
No full textDans cette thèse, j'examine les liens existants entre l'engagement politique et la reconstruction identitaire chez des personnes Métis expérimentant, dans une grande majorité, une déconnexion communautaire. A travers des entretiens semi-dirigés sous la forme de récits de vie, cette recherche explore la manière dont des personnes en phase de reconnexion avec leur environnement communautaire définissent leur sens de l'engagement et leur rapport à leur identité Métis. Grâce à un cadre théorique critique fondé sur la théorie postcoloniale et une revue de la littérature exposant les travaux de nombreux-ses auteur-trices Métis et autochtones à ce sujet, je soutiens la thèse que l'expérience de mes participant-es de leurs engagements politiques (et de leur politisation en générale) est viscéralement liée à leur processus de (re)construction identitaire. Ce constat est révélé à travers l'importance accordée à leur ancrage communautaire et familial dans leurs pratiques d'engagement, mais aussi par la centralité de ces relations dans leur manière d'appréhender leur héritage Métis, leur compréhension de l'identité (comme objet politique pluridimensionnel) et le sens de l'engagement comme pratique située
The Effect of Sox9 on Cell Growth and Stemness in HER2-Positive Breast Cancer
No full textBreast cancer is one of the most diagnosed and fatal malignancies, and its incidence increases each year. The HER2-positive subtype is associated with aggressive disease and poor outcome, with a high risk of acquired resistance to first-line treatment. A key contributor to these qualities is epithelial-to-mesenchymal transition (EMT). Sox9 has been linked to tumorigenesis and EMT in many cancers, but its role in HER2-positive breast cancer has yet to be fully characterized. Previous studies have identified a gene network downstream of HER2 that promotes a stem-like phenotype in vitro and reduces overall survival in vivo due to Sox10 upregulation through a PDK1-AKT-Sox9 axis, and we have shown that Sox10 deletion reduces stemness and inhibits hyperplasia. We hypothesized that Sox9 drives a distinct genetic program required for invasion and the maintenance of stem cells. To determine the effect of Sox9 on cell phenotype we have generated Sox9-deficient cells with a CRISPR/Cas9 knockout and Sox9-overexpressing cells by lentiviral transduction. In vitro characterization of these cells demonstrated significant decreases in proliferation, sphere-forming, and invasion in the Sox9-deficient cells with stronger effects observed in complete knockout cells compared to those with residual Sox9 expression. RNA-sequencing revealed an upregulation of epithelial-associated genes in Sox9-deficient cells. Lastly, we have shown that Sox9-deficiency inhibits expansion in vivo using orthotopic and tail-vein injection models. Together, our findings suggest that Sox9-knockout inhibits stemness in HER2-positive tumour-derived cells. Further insight into the role of Sox9 may reveal novel therapeutic targets for breast cancer treatment