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Cognitive Abnormalities in Long COVID: Discovering Patient Subtypes using Machine Learning
No full textLong COVID is a complex and heterogeneous condition affecting millions worldwide, with cognitive dysfunction emerging as one of its most debilitating and poorly understood symptoms. While neuroimaging studies reveal brain alterations, they may not fully capture the underlying patterns that traditional statistical analyses often overlook. This study applies machine learning to identify neurocognitive subtypes in Long COVID using multimodal MRI data. We compared four hierarchical clustering methods, grey matter-based, white matter-based, structural (combined grey matter and white matter), and a novel multilayer network approach; using Ward’s linkage to ensure consistency. Standardized neuroimaging preprocessing and dimensionality reduction were applied, with clustering performance evaluated through internal and external validation metrics. Results identified distinct neurocognitive subtypes with varying brain structure alterations, cognitive performance, and health metrics. The multilayer network approach outperformed traditional methods, effectively capturing complex grey and white matter interactions. Significant cognitive impairments were linked to specific brain degeneration patterns in population with higher comorbidity risks and more severe symptoms during the acute infection. These findings highlight the potential of machine learning in refining the understanding of Long COVID by identifying structural markers to distinguish different patient subtypes
INVESTIGATION OF THE NOVEL INTERACTION BETWEEN THE HUMAN RECEPTOR FOR ACTIVATED C KINASE 1 (RACK1) AND 26S PROTEASOME
No full textThe 26S proteasome is a highly conserved protein degradation complex. It facilitates ATP- and ubiquitin-dependent protein degradation and plays a central role in the ubiquitin-proteasome system (UPS). The proper function of the proteasome is essential for maintaining protein homeostasis by removing damaged and misfolded proteins as well as regulating protein turnover under various physiological and pathological conditions. RACK1, a highly conserved WD40 repeats scaffolding protein, is known for its ability to coordinate diverse protein-protein interactions. RACK1 is involved in the protein homeostasis network by serving as a platform for recruiting protein substrate or co-factors, as well as organizing protein complexes formation. Interestingly, RACK1’s involvement in the regulation of proteasome function has not been thoroughly explored.
This study identified a novel interaction between RACK1 and the proteasome, shedding light on RACK1’s potential role in regulating proteasome activity. RACK1 was found to directly interact with 26S proteasome preferentially with 19S regulatory proteasome subcomplex through the N-terminal three WD repeat. RACK1 selectively enhances the proteasome’s trypsin-like activity in a purified protein system without affecting other catalytic activities. In the cellular context, RACK1 was shown to play a role in maintaining basal proteasome gene expression independently of NRF1 and NRF2 activation, the master transcription factors regulating proteasome genes. Furthermore, RACK1 was found to mitigate stress-induced NRF2 and proteasome gene expression, potentially through its role in maintaining proteasome activity and mitigating oxidative stress. These findings provide valuable insights into the regulatory interplay between RACK1 and the proteasome.
In summary, this study establishes RACK1 as a novel and multifaceted regulator of proteasome activity, participating in both direct modulation and transcriptional regulation of proteasome function. These findings expand our understanding of the mechanisms governing proteasome function and highlight the potential of RACK1 as a therapeutic target in diseases associated with proteasome dysfunction and impaired protein homeostasis
Advancing Air Pollution Monitoring Assessment in Eastern Canada with Emerging Methods
No full textSurface air pollution monitoring networks in eastern Canada, including Ontario, Quebec, and the Atlantic provinces, have limited coverage and high deployment and maintenance costs. The Quebec City-Windsor corridor is Canada’s most densely populated region with the highest traffic and industrial activities, while the Atlantic provinces have high population proportions of vulnerable people. Without adequate monitoring, the exposure and population health risk assessment of air pollution lacks precision. New measurement technologies and methods enable high-resolution monitoring in under-monitored communities. Low-cost air quality sensors enhance the density of surface monitoring. This study assessed the spatial distributions of low-cost sensors and regulatory monitoring stations for fine particulate matter (PM2.5) in eastern Canada with locally adaptive kernel density estimation (KDE), and found persistent monitoring gaps and disparities in monitoring coverage in communities with social deprivation. A new remote sensing satellite instrument, Tropospheric Emissions: Monitoring of Pollution (TEMPO), provides raster observations of tropospheric column nitrogen dioxide (NO2) on a daytime hourly basis. Examining its high spatiotemporal resolution data, this study identified previously unrecognized NO2 hotspots, monitoring gaps in eight highly polluted and densely populated municipalities, and variations in temporal NO2 patterns. Linking the remote sensing to in-situ surface-level observations, with ancillary data of meteorology, land use, land cover, and urban environment, this study applied land use regression and hotspot mapping for air pollution monitoring gap assessment in a hyperlocal context. Saint John, New Brunswick, an industrial city with sulphur dioxide (SO2) pollution, was selected as a case study for intra-urban pollutant modelling. In summary, this thesis highlights current air pollution monitoring gaps in eastern Canada and informs future policy planning in monitoring expansion, resource management, and health surveillance in under-monitored communities. It also demonstrates the use of novel geospatial data and methods in studying air pollution and motivates future research
Senate Minutes, 2025
No full textElectronic document, no continuous page numbers (refer to adobe page numbers for index), notes in margins. Original minutes and additional materials are available through the Dalhousie University Archives and Special Collections Senate fonds (UA-5).The University Senate minutes contain information on faculty and program creation and modifications, academic schedules, admissions, affiliated institutions, alumni information, appointments, committees, faculties, biographical sketches of key members of the Dalhousie community and other information on administrative duties involving the Senate
ON THE MAGNITUDE AND SEASONAL VARIABILITY OF PCO2 AND AIR-SEA CO2 FLUXES IN THE NORTHWEST ATLANTIC OCEAN
No full textThis thesis focuses on the variable pCO2 at the sea surface, a critical variable used to calculate air-sea CO2 fluxes. First, we analyze the technical problems and challenges of accurately measuring pCO2 (and pCO2 data treatment) using underway systems with varying levels of complexity (Chapter 2). This is followed by a discussion of data-availability, data-coverage and related uncertainties in the seasonality of pCO2 and air-sea CO2 fluxes in the Central Labrador Sea, where a compilation of pCO2 observations was made in this data-poor region to create a baseline seasonal climatology (Chapter 3). Finally, the effects of additional observations and resolution were addressed for the Northwestern Atlantic
using a neural network approach for filling gaps in observations (Chapter 4). Overall, an investigation of the magnitude and seasonal variability of pCO2 and air-sea CO2 fluxes was made for the Northwest Atlantic Ocean, with special focus on the Labrador Sea and adjacent continental shelves.Oceanic uptake of atmospheric CO 2 plays a major role in regulating climate and mitigating the impact of its increasing concentration on global temperature. This thesis is focused on observations of surface-ocean partial pressure of CO2 (pCO2) and air-sea CO2 fluxes, particularly on the Northwest Atlantic Ocean. First, an overview of the marine carbon cycle and air-sea CO 2 fluxes is presented (Chapter 1). Then, a study analysing how new sensor-based pCO2 systems compare with more conventional but complex measuring systems is presented (Chapter 2). This comparison showed promise for a technological change that could be crucial for expanding our observational/monitoring network on ships
of opportunity, research vessels, and using new platforms for ocean observation. The next study presented is a compilation of all pCO 2 observations available for the Central Labrador Sea (Chapter 3), where a base-line reference climatology was created for this region and compared against an ensemble of global products, showing large discrepancies between these products and the observational climatology produced here. The last study (Chapter 4) presents a gap-filling reconstruction of pCO2 maps for the Northwest Atlantic, using a neural network approach. These reconstructions were done with new observations and different spatial resolutions, and the effects of additional data and finer
resolution on pCO2 and air-sea CO2 fluxes estimates is discussed. Both Chapters 3 and 4 emphasize the problem of poor data coverage, specially in high latitudes regions of the North Atlantic, pin-pointing where and when additional observations are necessary for improving constraints of air-sea CO2 fluxes. Therefore, this thesis contributes to improving potential for future data-coverage by validating a new simpler pCO2 measuring system (DAL-SOOP). The thesis also provides a compilation of pCO2 observations, producing a baseline seasonal climatology for the Central Labrador Sea. Comparison of this reference against other observational-based global products revealed systematic differences in the
representation of the seasonal cycle of pCO2 and uncertainties in the magnitude of air-sea CO2 fluxes. Finally, the reconstruction of pCO2 maps in the Northwestern Atlantic Ocean contributes to new estimates of air-sea CO2 fluxes for regions that are poorly sampled. This study highlights the need to increase observation capability, specially in data-poor locations and in regions with high variability of pCO2 and intense CO2 fluxes
Assessing The Associations Between Asbestos Exposure and Breast Cancer Incidence Among Nova Scotian Females in a Longitudinal Cohort Study
No full textBreast cancer is common among female populations worldwide. While many risk factors for breast cancer are well-established, potential associations between asbestos exposure and breast cancer incidence remains a subject of ongoing investigation. This population-based study utilized data from 8,808 cancer-free females in Nova Scotia. Multivariable logistic regression was used to assess associations between three binary indicators of asbestos exposure (at work, at home and overall) and breast cancer incidence, adjusting for various confounders. Increased odds of breast cancer among participants reporting prior asbestos exposure in the workplace was noted (AOR = 1.75, 95% CI: 1.00 – 3.06). Elevated risks were observed for following occupational asbestos exposure (AOR = 2.18, 95% CI: 1.21 – 3.92) and overall asbestos exposure (AOR = 1.82, 95% CI: 1.06 – 3.11) among females 50 years of age or older. These results warrant further investigation to uncover potential biological mechanisms and confirm observations among other populations
MICROPLASTICS IN AGRICULTURAL SOIL AMENDED WITH ALKALINE-TREATED BIOSOLIDS
No full textMicroplastics (MPs) are emerging ubiquitous environmental contaminants that risk agricultural sustainability and food security through the land application of biosolids. This research quantified MPs in alkaline-treated biosolids (ATBs) and evaluated their accumulation, persistence, and vertical movement in agricultural soils over 15 years. ATBs contained an average of 138 600 MP particles kg⁻¹ (dry weight), predominantly fragments. Repeated ATB applications led to significant MP accumulation in surface soils (0–15 cm), with an 8.7-fold increase observed under 14 tonnes ha⁻¹ applications. MPs persisted long-term, even in single-application plots, and smaller MPs preferentially migrated deeper into the soil profile. To enhance MP characterisation, thermogravimetric analysis (TGA) paired with differential scanning calorimetry (DSC) and Fourier-transformed infrared (FTIR) spectroscopy was used to successfully identify polypropylene (PP), polyethene (PE), and polystyrene (PS). These findings underscore the need for improved regulatory oversight and monitoring strategies to mitigate MP contamination and protect agricultural sustainability and food security
Electrical and Thermal Performance Evaluations for Repurposed Electric Vehicle Batteries in Second Life Electricity Grid Energy Storage
No full textThe yearly production of lithium-ion batteries for electric vehicles (EVs) is expected to increase sevenfold by 2035 to enable decarbonization of the transportation sector. When an EV battery is removed from EV service, it can usually be repurposed to serve a ‘second life’ in electricity grid energy storage before it is finally recycled to recover key materials. Second life batteries have been the subject of much research and development in recent years, but there are still many challenges that need to be overcome in this new industry. For example, since there are many different EV battery designs with unique performance characteristics, second-life battery researchers and developers must have the means to characterize the electrical and thermal performance of any EV battery in a consistent and comparable way. The adoption of appropriate performance evaluation methods would allow researchers and developers to assess and compare the various strengths and weaknesses of different EV batteries for the purposes of modelling, designing, and operating second-life battery systems.
This thesis presents novel research focused on evaluating the second-life performance of used EV batteries. The objective is to develop suitable electrical and thermal performance evaluation methods, and to use these methods to compare the performance of different EV battery designs. To achieve this objective, five unique EV batteries are acquired and tested at the pack level using a series of constant power tests. The test results are used to compare the five battery packs according to 21 performance metrics, revealing significant performance differences among different EV battery designs. Despite these differences, the test results are shown to vary predictably with the applied power rate based on a set of novel empirical equations, leading to a newly proposed method for standardized second life battery performance characterization. A specialized thermal model is also developed to facilitate real-time monitoring of temperature distributions in second life battery packs. Altogether, the research outcomes contribute powerful new tools and practical insights for the second-life battery industry
THE DEVELOPMENT AND APPLICATION OF BRUVS-LITE: A STEREO-BRUV SYSTEM WITH INTEGRATED LIGHTING FOR SEASCAPE ECOLOGY
No full textBaited Remote Underwater Video Systems (BRUVS) are cost-effective and non-invasive monitoring tools used widely throughout marine ecology. Since their development, the use of BRUVS has expanded considerably. However, most BRUVS surveys have been conducted in the photic zone of the Southern Hemisphere, with limited studies exploring their effectiveness in low-light or aphotic environments. Furthermore, BRUVS in these regions typically lack integrated lighting and record continuous video over short deployment durations. Significant knowledge gaps remain regarding the use of BRUVS in northern latitudes.
Seascape ecology, a rapidly emerging field in marine research, draws from concepts established in landscape ecology to examine the influence of habitat structure on species distributions and ecological processes. A key focus within seascape ecology is edge habitats, or ecotones, which describe zones of transition between habitats of differing structural complexity. In marine ecosystems, ecotone research has typically focused on discrete habitat types displaying clear boundaries (e.g., seagrasses). Significant knowledge gaps remain in marine environments characterized by more broad-scale heterogeneity and gradual transitions. Additionally, the use of BRUVS to assess marine ecotones is controversial, as the use of bait may introduce biases that obscure natural habitat associations.
This research presents BRUVS-Lite, an open-source, cost-effective, and user-friendly stereo-BRUV system with integrated lighting, and its application for seascape ecology. This study details the design, and proof-of-concept testing of BRUVS-Lite. Additionally, an assessment of the length measurement accuracy of BRUVS-Lite was conducted, focusing on the impact of routine system handling on stereo-camera calibration stability. Finally, BRUVS-Lite was applied for seascape ecology within the Eastern Shore Islands, Nova Scotia, to investigate the marine ecotones between rocky reef and sand habitats. Both baited and un-baited deployments were conducted to evaluate the effectiveness of each methodology in detecting species-habitat relationships along ecotones. Additionally, this study aimed to provide recommendations for the optimal BRUVS-Lite deployment duration.
This study demonstrates the effectiveness of BRUVS-Lite as a monitoring tool across diverse marine environments. However, routine system handling was found to significantly impact calibration stability, emphasizing the need for system calibration before and/or after each deployment for accurate length measurements. BRUVS-Lite effectively detected ecotone effects across both baited and un-baited deployments. The use of bait was not found to obscure species-habitat relationships, however, reactions to bait were generally considered to be species-specific. The optimal BRUVS deployment duration in this region was found to be approximately 6-7 hours. By addressing knowledge gaps in both BRUVS methodology and seascape ecology, this study aims to advance our understanding of species-habitat relationships in temperate ecosystems and inform best practices for BRUV-based ecological monitoring in northern latitudes.Baited Remote Underwater Video Systems (BRUVS) are widely used in marine ecology but remain understudied in low-light environments and northern latitudes. Within seascape ecology, a key focus is edge habitats (ecotones), which describe zones of transition between habitats of differing structural complexity. Previous ecotone research has predominantly occurred in habitat types displaying clear boundaries (e.g., seagrasses). Knowledge gaps remain regarding environments characterized by broad-scale heterogeneity and gradual transitions. Use of BRUVS to assess ecotones is controversial, as bait may introduce sampling biases. This research presents BRUVS-Lite, an open-source, cost-effective, stereo-BRUVS with integrated lighting. Assessment of the measurement accuracy of BRUVS-Lite was conducted, focusing on the impact of routine system handling on calibration stability. BRUVS-Lite was applied for seascape ecology within the Eastern Shore Islands, Nova Scotia, to investigate ecotones between rocky reef and sand habitats, while evaluating the effectiveness of baited and un-baited deployments in detecting species-habitat relationships