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Investigating dentition development and replacement in Mexican tetra two subforms
No full textMexican tetra (Astyanax mexicanus) is a teleost fish which has become a popular animal model in developmental biology research. There are two main subforms in Mexican tetra: the river-dwelling surface fish and cave-dwelling blind fish. Previous studies have indicated that cavefish possess a greater number of teeth compared to surface fish. However, detailed understanding of tooth development and replacement in Mexican tetra remains limited. This project aimed to explore the potential causes behind the differences in tooth count between surface fish and cavefish by characterizing the features of the mandibular dentition in adult surface fish and Pachon cavefish and by describing the process of first generation of dentition development in larval fish.
Surface fish and Pachon cavefish were sacrificed to investigate the normal dentition of adult Mexican tetra. Tissue processing was carried out on mandible samples, followed by the preparation of transverse histological sections. For the study of early dentition development, larval Mexican tetra surface fish and Pachon cavefish at 12-, 18-, 21-, 24-, and 30-days post-fertilization were sacrificed for histological analysis. Additionally, immunohistochemistry was employed to detect the expression of the odontogenic marker Sox2.
Results indicated that Mexican tetras replace their functional teeth via successional dental lamina marked by Sox2 expression. Compared to adult surface fish, adult Pachon cavefish possess more intraosseous replacement teeth. In early dentition development, the development of mandibular teeth was marked by Sox2 expression. No continual dental lamina was observed, nor were there significant morphological differences in developmental structures between the two subforms.
Our findings confirm the morphology and localization of successional dental lamina in tooth replacement in Mexican tetra but provide no evidence that the first dentition develops according to a continual dental lamina pattern. The first-generation teeth may develop independently in the single tooth development pattern. The results from this project will offer valuable histological information for future research into tooth development in Mexican tetra.University of Manitoba Graduate Fellowship;
Graduate Enhancement of Tri-Agency StipendsOctober 202
Correction: A scoping review on the links between sustainable development goal 14 and early childhood caries
No full textStock volatility forecasting with transformer network
No full textFinancial world faces many uncertainties due to decisions by governments, business entities, technology trends, natural calamities etc. Stocks and stock market form one of the major activities in financial world. Volatility is one of the main measures of uncertainty in financial stock markets. Hence, forecasting stock volatility is a critical component in many financial problems such as financial risk management, optimizing portfolios etc. In addition to traditional statistical techniques, there have been few artificial intelligence (AI) and machine learning (ML) techniques used in the literature for this volatility forecasting problem. Transformer Network (TN) architecture is one of newest ML techniques. For this thesis work, we utilized TN architecture with multi-head attention (MHA) mechanism for stock volatility forecasting. To enhance the performance of the TN, we incorporated different variations of the feed forward layer. The performance of three distinct TN models was evaluated by implementing three different deep learning (DL) layers (CNN, LSTM, and a hybrid layer CNN LSTM) in the encoder block of TN as the feed forward layer. The results clearly demonstrate that the TN model with the hybrid layer (CNN-LSTM) outperformed the other models, including a recently proposed data-driven approach. Furthermore, we assessed the performance of another latest model that is on built on TN known as Informer model on a minute-scale Bitcoin dataset across various forecast lengths. Our findings underscore the advantages of the Informer model, specifically its ProbSparse attention mechanism and distilling operation, which substantially enhances its efficiency in handling long sequence time-series forecasting (LSTF) tasks.May 202
Navigating MNE control and coordination: A critical review and directions for future research
No full textControl and coordination efforts are at the heart of MNE functioning. Yet, our review reveals that the literature on MNE control and coordination lacks conceptual clarity, which may hamper the development of the field. In this critical review, we synthesize the literature over the past decade using a conceptual framework rooted in new internalization theory. Research remains fairly coarse regarding how various configurations and interactions of control and coordination mechanisms affect intended outcomes. We note a paucity of multilevel studies, direct investigations of microfoundations, and comparison studies between intra- and inter-MNE relationships. Insufficient attention has been paid to adaptation issues and the impact of external dynamics on the need for, and operationalization of, control and coordination mechanisms. These gaps are concerning, since external trends are changing the organizational landscape and MNE boundaries are becoming increasingly fuzzy. Going forward, a more nuanced conceptualization of outcomes is needed, one that specifies proximal outcomes which mediate the achievement of distant goals. We use our augmented conceptual framework to identify other key areas for future research. We also call for more research on how disruptive forces affect both the use and outcomes of organizational mechanisms aimed at achieving control and coordination
Promoting brain health and resilience: the effect of three types of exercise on blood-based neurotrophins
No full textExercise is positively related to aspects of brain health through mechanisms involving blood-based neurotrophins released in the brain and from skeletal muscle. Neurotrophins are neuroprotective, promoting the growth and plasticity of neurons in the brain. However, the differences and/or similarities of exercise type on neurotrophic release in the cardiovascular system have yet to be established. We evaluated the acute effects of moderate-intensity continuous exercise, high-intensity interval exercise, and resistance exercise on Brain Derived Neurotrophic Factor, a protein involved in promoting neuroplasticity along with secondary measures of brain health: heart rate variability (HRV), self-reported positive and negative affect, and grip strength. In a repeated measures cross-over design, 12 participants over 5 weeks underwent all three exercise types while phlebotomy, cardiac, affect and grip strength measures were taken pre-, immediately post-, 30-minutes, and 60-minutes post-exercise. Results showed a significant change in plasma BDNF concentrations across all exercise types from immediately post-exercise to the 60-minute post-exercise time interval. Cardiac measures showed a decrease in heart rate variability immediately post-exercise, followed by a gradual increase to above pre-exercise levels at 60-minutes post exercise. A decrease in negative affect following exercise was also observed from immediately post- to 60-minutes post-exercise. No significant changes in grip strength were observed. Taken together, the results suggest that although exercise type did not differentially affect BDNF, HRV, or negative affect, all three measures suggested a consistent trend of physiological and psychological improvement or recovery trend at 60-minutes post exercise, highlighting the potential widespread benefits of various forms of exercise on aspects of brain health.October 202
First minister choices regarding cabinet committees: the Manitoba experience 1958-2021
No full textThis thesis looks at the use of cabinet committees in Manitoba as part of the cabinet decision-making process. Very little work has been done on this important facet of cabinet government in Canada. I address three research questions related to the use of cabinet committees under each of the premiers from 1958 to 2021. First, what was the structure of cabinet committees each premier employed? Second, what was the impact of these different structures on governance? Finally, how and why did the cabinet committee system change under each premier? By answering these questions, I argue that the Manitoba experience with cabinet committees reveals that the essential approach to governance taken by each first minister can be derived from their choices concerning cabinet committees. The research reveals that premiers in Manitoba rely on two committees as the pillars of their cabinet committee structure. The first committee is Treasury Board, which is a constant within the cabinet committee system. The second committee is either a coordinating committee or an economic development committee. Both committees are chaired by the premier. The thesis also looks at the use of government MLAs as part of cabinet committees.October 202
Canada needs a national COVID-19 inquiry now
No full textAbstract Background We are now in the fifth year of an ongoing pandemic, and Canada continues to experience significant surges of COVID-19 infections. In addition to the acute impacts of deaths and hospitalizations, there is growing awareness of an accumulation of organ damage and disability which is building a “health debt” that will affect Canadians for decades to come. Calls in 2023 for an inquiry into the handling of the COVID-19 pandemic went unheeded, despite relevant precedent. Canada urgently needs a comprehensive review of its successes and failures to chart a better response in the near- and long-term. Main body While Canada fared better than many comparators in the early years of the COVID-19 pandemic, it is clearly still in a public health crisis. Infections are not only affecting Canadians’ daily lives but also eroding healthcare capacity. Post-COVID condition is having accumulating and profound individual, social, and economic consequences. An inquiry is needed to understand the current evidence underlying policy choices, identify a better course of action on various fronts, and build resilience. More must be done to reduce transmission, including a serious public education campaign to better inform Canadians about COVID and effective mitigations, especially the benefits of respirator masks. We need a national standard for indoor air quality to make indoor public spaces safer, particularly schools. Data collection must be more robust, especially to understand and mitigate the disproportionate impacts on under-served communities and high-risk populations. General confidence in public health must be rebuilt, with a focus on communication and transparency. In particular, the wide variation in provincial policies has sown mistrust: evidence-based policy should be consistent. Finally, Canada’s early success in vaccination has collapsed, and this development needs a careful post-mortem. Conclusions A complete investigation of Canada’s response to the pandemic is not yet possible because that response is still ongoing and, while we have learned much, there remain areas of dispute and uncertainty. However, an inquiry is needed to conduct a rapid assessment of the current evidence and policies and provide recommendations on how to improve in 2025 and beyond as well as guidance for future pandemics
Custom-made root-analogue dental implant
No full textDental implants are vital in modern dentistry, offering a durable and effective solution for various dental issues. Since their introduction for edentulous jaws, implants have been recognized as a reliable option for replacing missing teeth. Recent advancements in digital engineering, such as cone beam computed tomography (CBCT) and computer-aided design (CAD) techniques, have further enhanced implant dentistry. High-quality CT scans and sophisticated segmentation software now facilitate the reverse engineering of implants, enabling the creation of patient-specific root analog implants. This process involves generating computer models that accurately replicate anatomical features, including teeth. Direct metal laser sintering (DMLS), an additive manufacturing method, can then produce these customized implants, offering a faster and more patient-friendly alternative to traditional methods.
The project's goal is to advance implant dentistry by developing a semi-automated protocol for patient-specific implants. This protocol aims to promote the adoption of root analog implants produced via DMLS. The developed tools will help dental professionals manage complex cases more effectively, benefiting many patients and improving implant survival rates. This approach also simplifies the implantation process, reducing the technological burden on dental professionals.
Initially focused on custom-made implants, the project revealed inconsistencies in current fabrication methods, highlighting the need for standardized procedures. Our key achievements include a comprehensive review of custom-made root analog implants (RAIs). We developed a modeling protocol to convert CBCT scans of roots into scaffold roots, tested it with plastic prototypes, and manufactured titanium RAIs, which were CT-scanned and mechanically tested.
Our findings indicate that the field of custom-made implant fabrication is still developing, with no standardized methods or clear guidelines. The modeling protocol effectively transforms CBCT scans into lattice structures with the desired pore size, although adjustments are needed for printing accuracy and quality. Future research, including additional testing and refinements, will be crucial to improving the process and ensuring implant performance. Standardizing methods and guidelines could unify practices across the industry, leading to more reliable and consistent outcomes in implant fabrication.American Academy of Implant Dentistry 2022 Small GrantFebruary 202
Tracking freshwater fishes of conservation concern in Manitoba using environmental DNA
No full textThe loss and degradation of freshwater habitats in Canada threaten the rich array of plant and animal species supported within these ecosystems, threatening the biodiversity that these ecosystems sustain. Assessing the distribution of the species in these threatened ecosystems is necessary for the effective monitoring of the well-being of their populations and the ecosystem, but it can be difficult, as some species can evade traditional survey methods due to their elusiveness, size, range, or rarity. Environmental DNA (eDNA), which describes the pool of DNA present in an environment that can be collected in and isolated from environmental samples, offers an alternative to traditional surveying that can be more sensitive and less invasive. Therefore, I developed and validated TaqMan™ MGB probe-based eDNA assays for six freshwater fishes of conservation concern in Manitoba: Bigmouth Buffalo Ictiobus cyprinellus, Chestnut Lamprey Ichthyomyzon castaneus, Golden Redhorse Moxostoma erythrurum, Hornyhead Chub Nocomis biguttatus, Northern Brook Lamprey Ichthyomyzon fossor, and Silver Lamprey Ichthyomyzon unicuspis. The designed assays were validated in situ using paired eDNA and capture-based sampling and used to map the distribution of the above species from water samples collected and filtered from 129 sites across Manitoba in 2021–2023. I detected the eDNA of four of the target species outside of their historic range: Bigmouth Buffalo in the Roseau, Morris, and Assiniboine rivers; Golden Redhorse in Hazel Creek; Hornyhead Chub in waterbodies of the Winnipeg River watershed where it has not been reported previously; and Northern Brook Lamprey in Boggy River. Apart from Northern Brook Lamprey, the eDNA of all target species was not detected in at least one site within their historic range. Further research is needed to confirm if the lack of eDNA detections of the target species within their historic range is a result of range restriction, or if a refinement of the methods used is needed.University of Manitoba Science Enhancement of Grants (SEGS) Program (Faculty of Science), Fisheries and Oceans Canada Species at Risk Program, Great Lakes Fishery Commission, Faculty of Science Field Work Support Program, FishCAST (NSERC CREATE), GEN-FISH (Genome Canada), University of Manitoba Faculty of Graduate Studies, Dr. Ken Stewart Memorial Scholarship (Fish Futures), Richard C. Goulden Memorial ScholarshipOctober 202
Robust regression analysis using median nomination sampling
No full textIn this thesis, we introduce a novel methodology for robust regression analysis when traditional mean regression falls short due to the presence of heteroscedasticity or outliers. Unlike conventional approaches that rely on simple random sampling (SRS), our methodology leverages median nomination sampling (MedNS) by utilizing readily available ranking information to obtain training data that more accurately captures the central tendency of the underlying population, thereby enhancing the representativeness of the sample in the presence of extensive outliers. We propose a new loss function that integrates the extra rank information of MedNS data during the training phase of regression model fitting, thereby offering a form of robust regression. Through simulation studies, including a high dimensional and a non-linear quantile regression setting, and a real data application, we evaluate the efficacy of our proposed approach compared to its SRS counterpart by comparing the integrated mean squared error of regression estimates. We observe that our proposed method provides higher relative efficiency compared to its SRS counterparts when outliers are present in the data.October 202