VictorJuiz/thesis huggingface dataset:
Osteocyte Signalling in Response to Mechanical Loading after Physical Cellular Damage and Hyperglycemia

Osteocytes are cells that reside in the mineralized bone matrix. They are the cells that sense mechanical loading on the bone; and respond by directing biochemical signals to osteoclasts (for bone resorption) and osteoblast (for bone formation) to remodel the bone. However, it is unknown how mechanical forces affect signaling of osteocytes that are affected by physical damage and pathological chemical environment. In the bone, mechanical loading causes micro-cracks, which cause physical damage to osteocytes and initiate bone remodeling. However, the role of subsequent mechanical loading on osteocyte is unclear. In this study, we have developed an in vitro cell model to study the impact of mechanical loading on osteocytes with physical damage. This model re-created the spatial distribution of osteocyte and signals expression around micro-cracks as in vivo. The results showed that 1) subcellular physical damage upregulates remodeling signals in osteocytes at 24 hr after damage, 2) mechanical loading substantially upregulates these signals for remodeling in osteocytes with physical damage. Hydraulic pressure and fluid flow shear stress are two concurrent mechanical stimuli on osteocytes, since the fluid shear is driven by the pressure gradient in the interstitial fluid in bone. A new mechanical loading system was developed to apply the concurrent mechanical forces. The loading system was able to safely apply physiological loading magnitudes to cells cultured on glass slides. It was found that concurrent pressure and shear stress had an additive effect on the reduction of osteocyte apoptosis. High glucose concentration in diabetic patients has resulted in retarded bone accumulation, bone loss, and an elevated risk of bone fracture. Osteocyte sensitivity to mechanical loading could be a factor in this pathology. The hypothesis is that hyperglycemia suppresses the beneficial effects of fluid flow shear stress on osteocytes. We found that high glucose level abolished mechanical-loading-induced changes in osteocyte signals to regulate bone remodeling, while osmotic control medium having the same elevated osmolarity did not have significant effects. Elevated glucose levels in diabetic patients could have direct effects on osteocytes, adversely influencing osteocyte response to mechanical loading, consequently the bone remodeling process.

Keywords: diabetes
mechanobiology
microdamage
osteocyte
pressure
shear
Advisor: You, Lidan
Heat and Mass Transfer Around a Bubble on a Horizontal Surface in a Subcooled Flow

Early state heat and mass transfer processes around a nucleated bubble in a subcooled flow boiling is studied numerically. The model uses both boiling and condensation processes, in which microlayer evaporation, thermal boundary layer conduction and kinetic theory evaporation and condensation heat and mass transfer mechanisms, are included. In addition, the model includes a microlayer thickness prediction. The model is applied on a two-dimensional and a three-dimensional computational domain at different subcooling temperatures and flow velocities in presence of gravity. The heated surface superheat and the system pressure are kept constant in all simulations. The two phase model, Volume of Fluid (VOF) in ANSYS/FLUENT is used. The results of the study show the importance of each of the heat transfer mechanisms in various stages of the bubble growth. At the early stages of the bubble growth, the microlayer heat transfer is the dominant transfer mechanism, however, as the bubble grows, the evaporation through bubble upper surface becomes significant. Furthermore, results indicate that the isothermal bubble assumption, which is used in prior models, is not valid for the whole life of bubble growth. The new bubble diameter correlation is concluded from theoretical analysis, which is the function of both √t and t with the coefficient of Ja and Pr numbers. The numerical model predicted bubble lift off diameter at p=2.5atm,〖∆T〗_sup=9℃,〖∆T〗_sub=15℃ is 0.36mm that is predicted experimentally 0.39mm at the same operating conditions. By 7% of underestimation of lift off diameter, the numerical model is validated.

Keywords: Computational fluid dynamics
Fluid mechanics
Heat transfer with phase change
Horizontal surface
Multiphase flows
Subcooled boiling
Advisor: Ashgriz, Nasser
The Cellular and Molecular Mechanisms of Ischemia-reperfusion induced Lung injury

Lung transplantation is the last option to treat patients with end-stage lung diseases. One of the main problems of lung transplantation is ischemia-reperfusion-induced injury, which can cause primary graft dysfunction. Thus, it is pertinent that we better-understand the underlying mechanisms of IR-induced lung injury. In this thesis project, we investigated the cellular and molecular mechanisms of IR induced lung injury Protein kinase C (PKC) is involved in many pulmonary diseases and thus, may be a mediator of IR-induced lung injury. We found that over 500 genes related to TNF and NFκB are altered in human lung epithelial (BEAS-2B) cells after PKC activator stimulation. Furthermore, PKC activation induced apoptosis and cytokine production. Next, we investigated the role of protein kinase C delta (PKCδ), in IR-induced lung injury during lung transplantation. To study intrinsic cellular response of IR-induced lung injury, we designed a cell culture model that simulates the lung transplantation procedure. Using this model, we were able to replicate IR-induced cytokine production and necrotic cell death shown in animal/clinical studies. PKCδ inhibition by δV1-1 reduced inflammatory cytokine production and ER stress protein degradation, while changing the mode of cell death from necrosis to apoptosis. We further observed that PKCδ inhibition significantly improved lung functions in in vivo models, suggesting that PKCδ inhibition is a good therapeutic strategy to treat IR-induced lung injury. We also investigated the underlying mechanism of IR-induced necrosis. In lung transplantation procedures, necrosis is considered to be a major contributor to IR-induced lung injury. Using our simulated IR cell culture model, we found that necroptosis and calpain activation mediates IR-induced necrosis and mitochondrial dysfunctions. We also found that calpain activation promotes necrosome complex to translocate to mitochondria, suggesting that calpain activation is necessary for necroptosis signaling. Calpain also activates STAT3 phosphorylation and ER stress activation, implicating that calpain is the major player of IR-induced cell death. In this project, we found several mechanisms related to cell death and inflammatory response in IR-induced lung injury. Thus, my findings will be valuable information in the field of lung transplantation research and potentially introduce new therapeutic strategies to lung transplant settings.

Keywords: acute lung injury
cell death
ischemia reperfusion
lung transplantation
Advisor: Liu, Mingyao
Canadian Federalism, Abeyances, and Quebec Sovereignty

This dissertation examines the changing patterns of intergovernmental relations among political elites toward sensitive constitutional issues implicated in the Quebec sovereignty movement, in particular after the 1995 referendum on Quebec sovereignty-association. It extends David Thomas' concept of constitutional "abeyances" to suggest that areas of constitutional ambiguity over which there are strong enough disagreements to lead to a national breakup can be successfully managed given enough political will. This depends on their being enough political actors who otherwise share a common interest in national unity willing to keep abeyances from escalating into a crisis. The exposure and politicization of such abeyances in the middle of the 20th century raised the salience of constitutional disagreements in Canada nearly to the point of national disintegration. The decline in the salience of these abeyances and the waning of support for sovereignty in Quebec since the last referendum has reduced this possibility substantially. Using a mixed method approach within an historical institutionalist framework, this dissertation argues that, along with other social forces, this is partially explicable in light of the fact actors such as the courts, federalist political leaders, and their parties have been willing to avoid discussing sensitive constitutional abeyances and leave them unresolved in the interests of avoiding a constitutional crisis. This has certainly not resulted in end of the sovereignty movement in Quebec, which remains very much alive. However, along with other political and social forces the willingness to keep deep constitutional disagreements camouflaged has permitted Canadian federalism to regain a measure of stability.

Keywords: Abeyances
Canada
Constitution
Federalism
Quebec
Advisor: Skogstad, Grace
Cameron, David M
Examining Child Welfare Outcomes for Asian-Canadian Children and Families: A Mixed Methods Study

This three-paper dissertation triangulated three different data sources using mixed methods to build a comprehensive understanding of Asian-Canadian households involved in the child welfare system at the national and local levels. The first paper used a mixed method approach to build a descriptive profile of Asian-Canadian households involved in the child welfare system. The results from secondary data analysis using the 2008 Canadian Incidence Study of Reported Child Abuse and Neglect (CIS-2008) indicated substantive differences between Asian-Canadian and White-Canadian households investigated by child welfare agencies. These results were presented to focus groups consisting of child protection workers and community service providers, eliciting practice insights and improved understanding of child welfare decision-making. The second paper compared child maltreatment investigations in the CIS-2008 to Canadian Census child population data. The study found that Asian-Canadian households were under-represented in the child welfare system and had almost two times the odds of case closure after an investigation compared to White-Canadian households. Three different disparity indexes were used in the analyses: population-based, decision-based, and maltreatment-based. The results demonstrated the need for greater clarity and consistency in the definitions and methodology for examining racial disparity in child welfare research. The third paper used administrative child welfare data from the Ontario Child Abuse and Neglect Data System (OCANDS) to examine the decision to close after investigation rather than transfer to ongoing child protection services (CPS). Compared to White-Canadian households involved in the child welfare system, Asian-Canadian households received ongoing CPS for over a month longer and were almost half as likely to be re-investigated within one year after case closure. This suggests that child protection investigations involving Asian-Canadian households may not be closed prematurely, but rather, provided the necessary intervention. Together, the three papers examine the profile of Asian-Canadian households in the child welfare system as well as child welfare decision patterns and services provided to this group. The discussion section for each paper and the dissertation's conclusion summarizes the study results, limitations, and implications for social work and child welfare research, theory and practices.

Keywords: Asian
Child Protection
Child Welfare
Disparity
Disproportionality
Families
Advisor: Fuller-Thomson, Esme
A New Approach to Robot Manipulation

This thesis discusses a new approach to the design, development and configuration assignment of Reconfigurable Robot Manipulators. It details the engineering of a new Modular, Autonomously Reconfigurable Serial manipulator platform, termed the MARS Manipulator, as well as a systematic methodology for obtaining the optimum configuration given a user-defined task. The platform consists of i) an 18-Degree-of-Freedom (DOF) serial-link manipulator capable of locking any of its joints at any position in their continuous range, such that it can emulate lesser DOF serial manipulators with different kinematic and dynamic parameters, and ii) an integrated simulation and design environment that provides a toolset for the design, implementation and optimization of a desired manipulator configuration for a given task. The effectiveness of the MARS Manipulator to adapt its configuration to various tasks is examined by assuming two well-known configurations, SCARA and articulated, and by performing a specific task with each of them. The variation in effectiveness of the two configurations in terms of the end-effector trajectory, end-effector accuracy and power consumption is discussed. Further, these configurations are optimized with respect to their performance accuracy, and compared to their pre-optimized versions. Further, the simulation is validated against with the physical hardware prototype, running the same task. A method of determining an optimal configuration based on a user-defined task is presented, in which the joint space of the MARS Manipulator is treated as a 12-dimensional smooth configuration manifold. The manifold is discretized and ranked based on a variety of criteria, and then clustered into attractive and repellent regions. The user then specifies which regions are desired in the target configuration, and the manifold is reduced in dimension in order to maximize the number of attractive regions and minimize the number of repellent regions. Six manipulators were synthesized using this approach, and their effectiveness is compared.

Keywords: Autonomous
Optimization
Reconfigurable
Robotics
Serial-Link-Manipulator
Advisor: Emami, Mohammad R
Understanding your Education: Onkwehonwe and Guests Responsibilities to Peace, Friendship and Mutual Respect

This thesis explores how Guest participants have engaged with Onkwehonwe (Original People in Mohawk) worldviews as they enrol within post-secondary courses about Onkwehonwe topics, taught by Onkwehonwe instructors/professors from Onkwehonwe perspectives. In order to acquire an understanding of what it means to be a Guest, I spoke to nine Elders and Traditional Teachers on expected Guest behaviour and actions. These teachings along with teachings of Wampum Belts were used to understand and analyze the stories of nineteen Guest participants. Grounded by Onkwehonwe worldviews, the methodology of this research project centered ceremony. The data collection method was storytelling in sharing circles. In hosting three large sharing circles and seven small ones, participants answered open ended questions. These circles were hosted in Toronto, Ontario between September 2014 and April 2015. The main findings of this thesis are 1) the primary, secondary and post-secondary education systems are not providing students with a historically accurate or relevant current education in relation to Onkwehonwe people, histories and topics; 2) when participants engaged in Onkwehonwe courses and pedagogies they all experienced a paradigm shift that lead to personal and professional growth; 3) this growth fuelled a desire to work in solidarity with Onkwehonwe peoples and a responsibility to share the learnings with other Guest people. This thesis is novel and contributes to scholarly discourse on Onkwehonwe research as it employs Onkwehonwe methodologies with Guest only participants (other than myself). It also offers the term Guest instead of using words like ‘non-Aboriginal’, or ‘settler’ and provides alternative ways of looking at Onkwehonwe/Guest relationships. In staying true to the data collection method of sharing circles, dissemination of the last question is as a sharing circle chapter. Individuals that are interested in how decolonial methodologies can have practical applications as well as those interested in Onkwehonwe/Guest relationships will find this work of interest.

Keywords: Guests
Indigenous Education
Indigenous Worldviews
Onkwehonwe
Advisor: Restoule, Jean Paul
Application of Gaussian Moment Closures to Three-dimensional Micro-scale Flows

A parallel, implicit, adaptive mesh refinement (AMR), finite-volume scheme is described for the solution of the standard and regularized Gaussian moment closures on three-dimensional, multi-block, body-fitted, hexahedral meshes. The standard Gaussian closure has been shown to accurately predict non-equilibrium phenomena at moderate Knudsen numbers through an anisotropic treatment of pressure. The regularized closure builds on these advantages and includes the effects of non-equilibrium heat transfer by means of a first-order correction to the standard Gaussian closure. The combined moment closure treatment / numerical method is applied to the prediction of three-dimensional, non-equilibrium, micro-scale, gaseous flows. Unlike other regularized moment closures, the underlying closure is the standard maximum-entropy Gaussian closure which provides a fully-realizable and strictly hyperbolic description of non-equilibrium gaseous flows that is valid from the continuum limit, through the transition regime, and up to the free-molecular flow limit. The proposed finite-volume scheme uses Riemann-solver-based flux functions and limited linear reconstruction to provide accurate and monotonic solutions, even in the presence of large solution gradients and/or under-resolved solution content. A rather effective and highly scalable parallel implicit time-marching scheme based on a Jacobian-free inexact Newton-Krylov-Schwarz (NKS) approach with additive Schwarz preconditioning and domain partitioning following from the multi-block AMR mesh is used to obtain solutions to the non-linear ordinary-differential equations that result from finite-volume spatial discretization procedure. Details are given of the standard and regularized Gaussian closure, extensions for diatomic gases, and slip-flow boundary treatment. Numerical results for several canonical flow problems demonstrate the potential of the closures, that when combined with an efficient parallel solution method, provide an effective means for accurately predicting a range of fully three-dimensional non-equilibrium gaseous flow behavior.

Keywords: adaptive mesh refinement
computational fluid dynamics
Knudsen number
micro-scale
moment closures
Newton-Krylov
Advisor: Groth, Clinton P. T.
Stochastic Correlation and Portfolio Optimization by Multivariate Garch

Modeling time varying volatility and correlation in financial time series is an important element in derivative pricing, risk management and portfolio management. The main goal of this thesis is to investigate the performance of multivariate GARCH model in stochastic correlation forecast and apply theses techniques to develop a new model to enhance the dynamic portfolio performance in several context, including hedge fund portfolio construction.\\ First, we examine the performance of various univariate GARCH models and regime-switching stochastic volatility models in crude oil market. Then these univariate models discussed are extended to multivariate settings and the empirical evaluation provides evidence on the use of the orthogonal GARCH in correlation forecasting and risk management performance when an equally weighted portfolio is considered. \\ The recent financial turbulence exposed and raised serious concerns about the optimal portfolio selection problem in hedge funds. The dynamic portfolio construction performance of a broad set of multivariate stochastic volatility models is examined in a fund of hedge fund context. It provides further evidence on the use of the orthogonal GARCH in dynamic portfolio constructions and risk management. \\ Further in this work, a new portfolio optimization model is proposed in order to improve the dynamic portfolio performance. We enhance the safety-first model with standard deviation constraint and derive an analytic formula by filtering the returns with GH skewed t distribution and OGARCH. It is found that the proposed model outperforms the classical Mean-Variance model and Mean-CVAR model during financial crisis period for a fund of hedge fund.

Advisor: Seco, Luis A
School Travel Planning in Canada: A Holistic Examination of Program Impact on Active School Travel

School Travel Planning (STP) is an intervention designed to increase Active School Travel (AST) among elementary school children (i.e., age 6-14 years). With limited evidence on program effectiveness, the purpose of this dissertation was i) to determine if STP can increases AST levels in Canadian elementary schools and ii) to identify school contextual and program factors influencing STP implementation and AST change. These objectives were addressed through four distinct studies entailing varied methodological approaches. Studies 1 and 2 quantitatively examined predictors of AST change following one-year of implementation using a sample of 106 schools across Canada and different outcome measures. Study 3 qualitatively explored enablers and barriers to implementation among 34 pan-Canadian STP facilitators. Study 4 employed a multisite mixed-methods case study design to provide insight into the STP process and key factors influencing implementation and AST change in two downtown Toronto schools. Across studies, results revealed that STP can facilitate increases in AST after the first year of implementation, though the degree of change can vary according to contextual and program factors. Contextual factors found to influence implementation and mode change included the school's geographical location, distance from students' homes, socioeconomic status, and transportation policies. Program factors included the school-specific and systematic STP model, multidisciplinary stakeholder involvement, designated facilitator, range of AST strategies, and length of implementation time. Overall, STP can promote increases in AST following one year of implementation. This dissertation informs future practice by identifying key factors to consider when implementing STP. The broader program of research also identifies the necessity of stakeholder involvement in initiatives promoting AST to help address a range of socio-ecological factors. Future evaluations should examine the sustainability of STP intervention impact and assess its cost-effectiveness.

Advisor: Faulkner, Guy