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Adjacency Effect in Nearshore Aquatic Remote Sensing: Modelling, Correction, and Application
No full textThe adjacency effect (AE) alters the top-of-atmosphere signals of coastal and inland waters, and it poses a major challenge for remote sensing of nearshore aquatic environments. To address this, we developed a Monte Carlo-based 3D radiative transfer model to study the AE, validated its accuracy against existing codes, and conducted case studies to demonstrate its application in analyzing the impact of AE in custom environments. In addition, we introduced a methodology and code for AE correction and demonstrated significant improvements in satellite-derived water-leaving reflectance retrievals using globally distributed in situ reflectance measurements. The tool, named T-Mart, is open-source and publicly available (https://github.com/yulunwu8/tmart). We applied AE correction and evaluated the performance and limitations of satellite-based water quality retrievals in small rivers traversing agricultural lands in Eastern Ontario, Canada. Satellite-derived reflectance and water quality parameters were validated against in situ measurements collected from May to October 2023. In the South Nation River and the Ottawa River, turbidity can be reliably monitored. Despite the improved retrievals through AE correction, further work is required to accurately monitor coloured dissolved organic matter and chlorophyll-a. While the findings highlight the complexities of satellite-based water quality monitoring applications for small rivers, AE correction represents a crucial step towards more accurate aquatic remote sensing of inland waters, laying the groundwork for more refined methodologies in future studies
Movement and Memory: Dance Archives and the Implications for Archival Appraisal
No full textThis thesis investigates the state of dance archives in Canada, focusing on collections held in the community. The research is exploratory in nature and uses an ethnographic approach to explore the state of the field and engage with people in the dance community to understand the perspectives and practices of people who create, care for, and use records of dance. This thesis investigates two central questions: how archives are used, and the challenges of documenting and archiving dance. Three complementary data collection methods are used to investigate these questions: a scoping review of publications in the field, a survey of community records and practices, and interviews with individual practitioners. This thesis demonstrates how the ephemeral nature of dance impacts its documentation, the importance of embodied knowledge, and the challenges communities face with regards to their archives. Dance archives also raise questions about the nature of the record, appraisal responsibility, and the connection between appraisal and acquisition.
Cette thèse présente une enquête sur l'état des archives de la danse au Canada, en se concentrant sur les collections conservées dans la communauté. La recherche est de nature exploratoire, utilisant une approche ethnographique pour explorer l'état du domaine et s'engager avec des individus dans la communauté de la danse pour comprendre les points de vue et les pratiques de ceux qui créent, conservent et utilisent les archives de la danse. Cette thèse examine deux questions centrales : les usages des archives et les défis de la documentation et de l'archivage de la danse. Trois méthodes complémentaires de collecte de données sont utilisées pour répondre à ces questions : une analyse des publications dans le domaine, un sondage sur les archives et les pratiques communautaires, et des entretiens avec des praticiens individuels. Cette thèse démontre l'impact de la nature éphémère de la danse sur sa documentation, l'importance de la connaissance incarnée et les défis auxquels les communautés sont confrontées en ce qui concerne leurs archives. Les archives de la danse soulèvent également des questions sur la nature du document, la responsabilité de l'évaluation archivistique et le lien entre l'évaluation et l'acquisition
Inter-cluster contamination: a semivariance analysis of community effect ranges of malaria vector control interventions in a four-armed malaria trial in Muleba, Tanzania
No full textAbstract Background The presence of a community effect in cluster randomized trials of malaria vector control interventions has led to the implementation of “buffer zones” around clusters to limit the potential for contamination between interventions. No consensus has been reached on how large these buffers need to be to encapsulate the effect. Methods Nested within a phase-III cluster randomized malaria vector control trial in Northwest Tanzania, this study aims to determine the presence and spatial range of community effects from long-lasting insecticidal net (LLIN) and indoor residual spraying (IRS) interventions on household-level malaria infection in trial clusters four months post-intervention. Effective spatial range estimates of intervention community effects were compared to the 300m buffer distance implemented to limit intervention spillover between clusters in the trial. Geographically-weighted adjusted odds of malaria infection in children aged 0.5–14 years were determined four months post community-level intervention with a randomized allocation comprising one of two LLIN products (OlysetTM LN: 1000mg/m2 permethrin or OlysetTM Plus LN: 400 + permethrin 800mg/m2) with either IRS (Actellic®300CS: 1000mg/m2 micro-encapsulated pirimiphos-methyl) or no IRS. Robust semivariances were calculated for each of 48 intervention clusters and fit to semivariogram models by Weighted Least Squares. Results 6440 children from 2785 households were included in the geographically-weighted logistic regression. Prevalence of Plasmodium falciparum infection was 45.9% in the study population. Twenty (20) clusters had significant residual effect ranges, 13 of which were fit to Sine Hole Effect models, indicating periodicity in the study area. Effective range estimates for the study area had a median value of 1210 m (IQR: 958–1691). Clusters with IRS had a higher median range value: 1535 m (IQR: 976–3398) than those without IRS: 1168m (IQR: 829–1504). Conclusions Significant semivariogram model range estimates extended beyond the trial buffer sizes by a median average of 868 m in LLIN intervention clusters and 1235 m for IRS clusters. This presents a contamination, or spillover, potential for all trialed intervention types that may reduce the statistical power to detect difference between trial arms. Future studies should consider the ranges of intervention effects and contamination potential between trial arms when designing buffer areas
Intrinsic Dysfunction in Muscle Stem Cells Lacking Dystrophin Disrupts Secondary Myogenesis and Postnatal Muscle Regeneration
No full textDystrophin deficiency is the underlying cause of Duchenne Muscular Dystrophy (DMD), a severe neuromuscular disorder characterized by progressive muscle degeneration and a significantly diminished lifespan. While DMD is conventionally understood to manifest postnatally due to cumulative muscle damage, the intrinsic dysfunction of muscle stem cells (MuSCs) also contributes to disease progression. Specifically, the absence of dystrophin-MARK2 interactions in activated MuSCs impairs their polarity, resulting in fewer asymmetric divisions and progenitor cells. However, the role of impaired MuSC polarity in muscle development and regeneration has not been extensively studied in vivo. Here, we describe the consequences of MuSC dysfunction during fetal, neonatal, and regenerative myogenesis using the mdx mouse model of DMD. We first characterized disease progression, muscle regeneration, and MuSC function in postnatal muscle. Dystrophin-deficient muscle undergoes progressive changes with age and delayed regeneration in response to acute injury. Moreover, defective MuSC polarity results in fewer progenitor cells at 5 days post-cardiotoxin injury and at neonatal day 7, before chronic inflammation and severe necrosis. We also observe that mdx MuSCs exhibit elevated PAX7⁺ cell engraftment with significantly fewer donor-derived myonuclei in regenerated myofibers. We next explored the developmental onset of mdx MuSC dysfunction. Examination of mdx mouse embryos lacking dystrophin revealed no impairment of the primary myogenic program. By contrast, histological and single cell RNA-sequencing analysis during secondary myogenesis uncovered a reduced proportion of progenitor cells relative to fetal (f) MuSCs, leading to fewer smaller-caliber myofibers. Wild type fMuSCs expressed full-length dystrophin that interacted with MARK2, whereas mdx fMuSCs downregulated MARK2 and NUMB and exhibited markedly reduced polarization. Strikingly, deletion of the Numb Associated Kinase, AAK1, restores NUMB expression in mdx fMuSCs and rescues the proportion of myogenic committed progenitor cells in mdx fetal muscle. Our data provides evidence that dystrophin deficiency in MuSCs and myofibers contributes to the progression of DMD. We also elucidate an acute disease pathology during DMD fetal development and the potential for therapeutic intervention by targeting MuSC
Prise en charge de la personne ventilée aux soins intensifs : une étude qualitative
No full textIntroduction : La ventilation mécanique est largement utilisée à l’unité des soins intensifs (USI). Au Canada, les infirmiers(ères) jouent un rôle central dans la prise en charge des personnes ventilées, prodiguant la majorité des soins directs et influençant les résultats et l’expérience de la ventilation mécanique. Or, de nombreuses barrières compliquent cette prise en charge et affectent les personnes ventilées. Il est donc essentiel de mieux comprendre ce rôle afin d’améliorer la qualité des soins.
Objectifs : Cette étude visait à 1) décrire la prise en charge d’une personne ventilée à l’USI selon les infirmiers(ères), 2) identifier les barrières à cette prise en charge, ainsi que les stratégies, les ressources et les besoins particuliers pour les surmonter et 3) proposer des pistes de solutions cliniques, empiriques et théoriques pour l’avancement des connaissances en soins intensifs.
Considérations méthodologiques : Une théorisation ancrée constructiviste a été privilégiée, puis une analyse thématique a également été réalisée. Au total, 30 infirmiers(ères) travaillant en soins intensifs, au Canada, ont été interviewés par téléphone, d’août à septembre 2020.
Résultats : Les résultats principaux proposent une modélisation théorique de la prise en charge des personnes ventilées – orchestrer les soins, où l’infirmier(ère) gère six domaines d’activités : 1) coordonner les soins et l’équipe, 2) communiquer l’information, 3) collaborer avec l’équipe interdisciplinaire, 4) surveiller l’évolution clinique, 5) répondre aux besoins et 6) assurer la qualité et sécurité. Ce processus, influencé par le contexte des soins intensifs, repose sur l’expertise infirmière qui évolue selon l’expérience et la compétence. Les résultats secondaires révèlent trois principales barrières : 1) les conditions de travail, 2) les connaissances et compétences et 3) le champ de pratique infirmier.
Conclusion : Cette thèse a mis en lumière la complexité et l’importance du rôle infirmier en soins intensifs lors de la prise en charge des personnes ventilées. Pour optimiser ce rôle, il est essentiel d’améliorer la formation en soins intensifs, renforcer l’autonomie décisionnelle des infirmiers(ères), de soutenir leur pratique et promouvoir leur expertise. Reconnaître pleinement ce rôle pourrait favoriser la rétention des infirmiers(ères) en soins intensifs et leur participation aux prises de décision, tant au chevet qu’à des niveaux plus stratégiques. Reste qu’une réorganisation de la pratique infirmière est nécessaire pour qu’ils(elles) puissent assumer pleinement leur rôle de chef d’orchestre et assurer une prise en charge globale des personnes ventilées et de leurs familles
Sulfonate-Based Single-Ion Conducting Polymer Electrolytes for Lithium Metal Batteries
No full textSolid-state batteries can offer improved energy density and safety relative to conventional liquid lithium-ion batteries. In particular, single-ion polymer electrolytes (SIPEs) offer high ionic conductivity, effectively suppressing lithium dendrite growth. In this study, a series of SIPEs composed of poly(ethylene oxide) methyl ether methacrylate (PEGMA) and poly(lithium 4-styrene sulfonate) (PLSS) were synthesized. These random copolymers (RCPs) were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization at six different compositions with PLSS content ranging from 12 to 75 mol%.
First, the chemical and thermal properties of the RCPs were fully characterized; all RCPs were found to have sufficiently high thermal degradation temperatures, with glass transition temperatures below room temperature. Next, PEGMA--PLSS films were prepared and tested for ionic conductivity using electrochemical impedance spectroscopy (EIS); copolymers exhibited high conductivity of 2.2 x 10⁻⁵ S cm⁻¹ at room temperature, reaching a maximum of 2.3 x 10⁻⁴ S cm⁻¹ at 70 °C. As PEGMA is the flexible, ion-transporting polymer, while PLSS contributes lithium ions and rigidity from functionalized polystyrene, the RCP with the lowest PLSS content (i.e., PEGMA--PLSS-12) exhibited the highest ionic conductivity but did not form free-standing films. Alternatively, films with more moderate amounts of PLSS resulted in both sufficient mechanical and ion transport properties. PEGMA--PLSS-50, which has the reported optimal ethylene oxide to lithium-ion ratio (EO:Li⁺) of 9:1, achieved the second highest room temperature conductivity (1.6 x 10⁻⁶ S cm⁻¹) and second highest ion conductivity at 70 °C (1.4 x 10⁻⁴ S cm⁻¹), while also forming free-standing SIPEs.
Considering the need to balance conductivity with mechanical properties, two methods were explored to improve the RCP SIPEs: (1) blending RCPs with poly(lithium vinyl sulfonate) (PLVS) and (2) synthesizing block copolymer analogs of the RCP (PEGMA--PLSS). Despite the low glass transition temperature of PLVS, it was not found to improve ion conductivity of PEGMA--PLSS-12. Due to differences in polymer solubility, polymer miscibility may be an issue at higher PEGMA compositions. Block copolymer synthesis is ongoing. PEGMA--PLSS copolymers show strong potential as a candidate for SIPEs for lithium metal batteries when synthesized with an optimal 9:1 ratio of EO:Li⁺ and conductivity may be further improved by transitioning to a block structure
It is time to acknowledge and act on the importance of power in integrated knowledge translation
No full textAbstract Integrated knowledge translation (IKT) has emerged as an approach to research centered on collaboration between researchers and knowledge users, particularly in health research. There has been a growing focus on power within the IKT literature, especially the concern that overlooking power inequities within IKT partnerships may reproduce forms of knowledge production and dissemination that do not align with IKT’s aspirations of shared decision making to produce useful and usable research findings. However, there remain significant gaps in our understanding of how to address and attend to power in IKT. The lack of conceptual precision around power complicates these efforts. In this commentary, we draw on existing literatures that have grappled with the notion of power to sensitize those who study and engage in IKT to the importance of power and to identify helpful ways of thinking about power in IKT. We propose that it is time to not only acknowledge the importance of power in IKT but also to develop empirically based strategies through which the many dimensions of power can be identified and navigated
A Morphological Analysis of Reactive Astrocytes in Alzheimer’s Disease: Therapeutic Implications of M1 Muscarinic Acetylcholine Receptor Modulation
No full textAlzheimer’s Disease (AD) is the most common form of dementia, disproportionally affecting females, who account for nearly 60% of diagnoses. In AD, beta-amyloid (Aβ) accumulation triggers neuroinflammation driven by neuroglia, exacerbating disease progression. Reactive astrocytes play a critical role in AD pathophysiology, yet their morphological changes remain poorly characterized. Our lab previously demonstrated that VU0486846, an orally available positive allosteric modulator (PAM) of the M1 muscarinic acetylcholine receptors (M1 mAChRs), enhances cognitive function, reduces Aβ pathology, and decreases astrocyte and microglial activation in the hippocampus of female APPswe/PSEN1ΔE9 (APPswe) mice. However, its effects on astrocyte morphology remain unclear. Using optimized immunofluorescence staining and 3D reconstruction techniques, this thesis assessed astrocyte morphology in female APPswe and wildtype mice. Astrocytes in the hippocampus and cortex of APPswe mice showed hallmark features of reactive astrogliosis, including hypertrophic somas and processes, elongated processes, and increased branching complexity. Chronic treatment with VU0486846 for eight weeks, beginning at 6-months old, significantly reduced astrocyte soma volume, process volume, process length, and branching complexity in APPswe mice, restoring astrocyte morphology to wildtype levels. These findings suggest that VU0486846 mitigates astrocyte reactivity, potentially reducing neuroinflammation and supporting neuronal health in AD. This thesis reveals a novel mechanism by which M1 mAChR PAMs exert disease-modifying effects, highlighting their ability to reduce astrocyte reactivity and emphasizing their potential as therapeutic agents for AD, particularly in females
Tracking Developmental Change in the Dopamine System Using Neuromelanin-Sensitive MRI in Children and Adults
No full textThe study of the dopaminergic system in humans has been predominantly obstructed by the lack of practical and advanced imaging techniques. Neuromelanin-sensitive MRI (NM-MRI) leverages the properties of NM, a byproduct of dopamine metabolism, to measure its accumulation in the Substantia Nigra (SN), and its impact on the function and integrity of the dopaminergic system, opening the potential for its use as a neuroimaging biomarker. In this thesis we explore NM-MRI to gain more insights into the function and dynamics of the dopaminergic system across the lifespan.
The first aim of this thesis is to identify the normative range of NM-MRI values in cognitively normal older individuals (53-86 years old), a key initial step towards its use as a clinical biomarker. Our results did not show any significant age-related change in NM metrics in this age range. The stable normative metrics in older individuals play an essential part in helping differentiate between normal aging processes and those marking the potential onset of neurodegenerative conditions.
The second aim explores the change in NM dynamics across the lifespan in the human brain. Two types of NM-MRI sequences are used to study these dynamics, Magnetization Transfer (MT) and Turbo Spin Echo (TSE). We found that throughout the SN, different clusters of voxels behave differently with age, highlighting the importance of voxelwise analysis when interpreting the patterns of NM accumulation within the SN, in parallel with looking at the SN as a whole structure.
The third aim looks for a potential correlation between NM signal within the SN and cognitive performance in young individuals. Our results show a strong positive link between NM signal accumulation in the SN and working memory performance, specifically localized in specific subregions of the SN. These results highlight the dynamic nature of the dopaminergic system in early life.
The fourth and last aim of this thesis compares the NM-MRI signal in a group of children and adolescents with Attention-Deficit-Hyperactivity-Disorder (ADHD) to age-matched healthy controls. A significant decrease in NM-MRI signal was observed in ADHD patients compared to their healthy peers, suggesting that lower dopamine levels in the SN could have an underlying role in the disorder. This makes NM a promising biomarker for diagnosis and treatment monitoring in ADHD.
Overall, this work reveals valuable insights into the differential development of NM patterns during life, reaffirming the growing utility of NM-MRI for future research and its clinical role for early identification of neurodegenerative and neurodevelopmental disorders
Enhancing reproductive health among adolescent girls in India: results of an individualized RCT to study the efficacy of the go Nisha go mobile game
No full textAbstract Background Adolescent girls in India face significant barriers to accessing sexual and reproductive health (SRH) information and services. Digital interventions, particularly mobile-based ones, promise to deliver SRH education in a fun and engaging manner. These can be offered privately directly to the adolescent, allowing players to ‘experience’ the outcomes of their choices, receive tailored feedback, and the option to ‘try again’. Methods This study evaluated the efficacy of “Go Nisha GoⓇ” (GNG), a low-end smartphone-based digital game for adolescent girls in India, using a two-armed, encouragement-led, randomized controlled trial (RCT). The study involved 1950 participants from Patna, Jaipur, and Delhi NCR. The intervention group received encouragement to play GNG, while the control group did not. Key constructs measured included menstrual health management (MHM), contraception knowledge, and agency. Data were collected at baseline and a ten-week follow-up. Results The intervention group showed significant improvements in various MHM parameters, contraception knowledge, and agency outcomes compared to the control group. Overall, 1697 out of 1993 participants completed the study after ten weeks (85%). The intervention group’s awareness of menstrual hygiene products increased from 33 to 92%, while comprehensive knowledge of oral contraceptive pills (OCPs) rose from 2 to 17% (p < 0.0001). Confidence in negotiating contraception use increased from 60 to 85% (p < 0.0001), and the attitude of refusing sex when not ready improved from 61 to 85% (p < 0.0001).The subjects in the game group showed high levels of satisfaction with the app, with 74% discussing the game with others and 66% recommending it. The belief in negotiating marriage decisions with parents also improved more in the intervention group than in the control group. Conclusion The findings of the first-ever RCT outcome evaluation for a digital mobile game app for enhancing SRH education among adolescent girls in low-resource settings support the efficacy of digital games for health like GNG. The game’s engaging and interactive format effectively communicated complex and sensitive SRH information, empowered participants, and encouraged (p < 0.0001) critical health behaviors through informed decision-making. Future studies could explore the long-term sustainability of behavior changes induced by such interventions and their effectiveness across different settings and populations. Trial registration number: CTRI/2023/03/050447. Date: March, 2023