VictorJuiz/thesis huggingface dataset:
Investigation of Discontinuous Deformation Analysis for Application in Jointed Rock Masses

The Distinct Element Method (DEM) and Discontinuous Deformation Analysis (DDA) are the two most commonly used discrete element methods in rock mechanics. Discrete element approaches are computationally expensive as they involve the interaction of multiple discrete bodies with continuously changing contacts. Therefore, it is very important to ensure that the method selected for the analysis is computationally efficient. In this research, a general assessment of DDA and DEM is performed from a computational efficiency perspective, and relevant enhancements to DDA are developed. The computational speed of DDA is observed to be considerably slower than DEM. In order to identify reasons affecting the computational efficiency of DDA, fundamental aspects of DDA and DEM are compared which suggests that they mainly differ in the contact mechanics, and the time integration scheme used. An in-depth evaluation of these aspects revealed that the openclose iterative procedure used in DDA which exhibits highly nonlinear behavior is one of the main reasons causing DDA to slow down. In order to improve the computational efficiency of DDA, an alternative approach based on a more realistic rock joint behavior is developed in this research. In this approach, contacts are assumed to be deformable, i.e., interpenetrations of the blocks in contact are permitted. This eliminated the computationally expensive open-close iterative procedure adopted in DDA-Shi and enhanced its speed up to four times. In order to consider deformability of the blocks in DDA, several approaches are reported. The hybrid DDA-FEM approach is one of them, although this approach captures the block deformability quite effectively, it becomes computationally expensive for large-scale problems. An alternative simplified uncoupled DDA-FEM approach is developed in this research. The main idea of this approach is to model rigid body movement and the block internal deformation separately. Efficiency and simplicity of this approach lie in keeping the DDA and the FEM algorithms separate and solving FEM equations individually for each block. Based on a number of numerical examples presented in this dissertation, it is concluded that from a computational efficiency standpoint, the implicit solution scheme may not be appropriate for discrete element modelling. Although for quasi-static problems where inertia effects are insignificant, implicit schemes have been successfully used for linear analyses, they do not prove to be advantageous for contact-type problems even in quasi-static mode due to the highly nonlinear behavior of contacts.

Keywords: Discontinuous Deformation Analysis
DDA
Distinct Element Method
DEM
discrete element method
Jointed Rock
Advisor: Curran, John H.
A Quantum-classical Investigation of Environmental Effects on Electronic Dynamics at Conical Intersections

In this thesis we employ the methods of quantum classical Liouville theory in order to explore the effects of an external environment on electronic dynamics, in systems containing conical intersections. In studying a simple, yet nontrivial, model in the gas phase we find that the short-time dynamics are well approximated by a hybrid MC/MD solution to the QCL equation. Upon including an external environment the population transfer profile changes, based on the various paramter values chosen. Electronic decoherence and the partial/complete destruction of geometric phase effects are also observed. Based on earlier work on master equation dynamics in QCL theory, we find that a Markovian approximation to the dynamics for systems containing conical intersections is not easily justified. In order to access longer time-scale phenomena another, less computationally demanding, solution method was also derived in the mapping basis. This method involves more severe approximations to the QCL equation than the MC/MD method, and as such is not as physically robust, yet still manages to reproduce some important aspects of the dynamics over a picosecond time-scale.

Advisor: Kapral, Raymond E.
Parental Involvement in School in a Double Minority Context: The Case of Racial Francophones

This study explored the involvement in school of racial Francophones in a large city in Canada. Specifically, the study investigated the involvement of Black francophone parents in two of Ontario’s publicly funded elementary schools. This study was guided by one main research question: How are Black francophone parents of African origin involved in their children’s formal education in the French-language schools? Five sub-questions stem from the main research question: How do Black francophone parents of African origin understand parental involvement in school? What strategies do these parents employ to become involved in their children’s formal education? What is the nature (i.e., extent, depth) of Black francophone parents’ involvement in their children’s formal education? What inhibits or facilitates the participation of these parents in the school? How is the double-minoritized positioning of these parents implicated in their participation and strategies? Using an anti-racist lens, the study revealed that Black francophone parents of African origin hold differing views regarding involvement in their children’s education. Although these parents treasure education and strive to instill personal values in their children, they express their understanding of involvement in school primarily in terms of cumulative negative experiences they have experienced and in some cases continue to experience with the French-language schools. Understanding of parents’ involvement in school was also encapsulated in terms of the parents’ own schooling experiences. For many, what constitutes involvement in school challenges the discursive meaning given to parental involvement in educational institutions, governments, and by mainstream parents. This study indicated that the extent to which Black francophone parents are involved in school and their strategies for involvement are rather poor. Moreover, the study singled out racism as one of the primary deterrents for Black francophone parents’ involvement in school. Other uncommon but significant barriers to parents’ involvement in school included: the impact of role inversion in the family; parents’ unawareness of the importance of their role in the education of their children; the blind-spot approach of parents to schooling; the absence of spirituality in parents’ lives; and the laissez-faire attitude of families rearing children.

Keywords: Home school relationship
Parent participation
Education of minority children
Schooling in Canada
Barriers to involvement in school
School racism
Black Francophones
Minority parents in school
French language schools
Involvement in French language schools
Blacks of African origin
Immigrant children in school
Barriers to academic achievement of minority students
Minority within a minority
Advisor: Ryan, James
Appreciative Inquiry: An Interactive Organizational Intervention to Translate Acute Pain Management Evidence into Pediatric Nursing Practice

Despite a substantial evidence-base for pediatric pain management, pain is not always well managed in clinical practice. Appreciative Inquiry (AI) is an innovative knowledge translation (KT) intervention that is compatible with the Promoting Action on Research in Health Services (PARiHS) framework. A prospective, repeated-measures, mixed-methods case study was conducted to (a) explore the implementation process of AI as a KT intervention in pain, (b) examine the beginning effects of AI on pain related outcomes, and (c) describe extraneous factors related to the PARiHS framework. Outcomes were measured at six and three weeks pre-intervention and three and six months post-intervention, ending with a semi-structured interview on the acceptability of the intervention. Data were analyzed using descriptive and inferential statistics, and quantitative and qualitative content analyses. Twelve nurses (nine staff and three administrative/clinical leaders) from a surgical unit at a pediatric hospital participated in the study. They perceived their context to be relatively complex, with a culture focused on clinical competence, family-centered care, and teamwork, and a transformational leadership style. Overall, participants were satisfied with the intervention structure, which consisted of four three-hour, interactive sessions delivered over two weeks to promote change based on positive examples of pain management on the unit, and suggested only minor refinements. The intervention was delivered with high fidelity and most participants (n = 11) attended all four sessions, where they developed an action plan to enhance evidence-based pain assessment documentation. There was a statistically significant improvement in participants’ pain knowledge and attitudes post-intervention. This outcome was significantly and positively correlated with participants’ attitudes towards research. Both of these factors had a significant relationship with participants’ effort to document pain assessments. Participants named AI a ‘refreshing approach to change’ because it was positive and democratic, with a focus on building on existing practices. They felt the process cultivated a positive reception to change, broadened their horizons around pain, and enhanced their team spirit. The facilitators were considered credible with effective communication skills. Given the promising results of this study, the refinement and evaluation of the AI intervention are warranted in other contexts and for other clinical practices.

Keywords: knowledge translation
pain
appreciative inquiry
nursing
evidence-based practice
intervention
Advisor: Stevens, Bonnie
Geophysical Imaging and Numerical Modelling of Fractures in Concrete

The goal of this research is to investigate the fundamentals of fracturing processes in heterogeneous materials such as concrete using geophysical methods and dynamic micromechanical models. This work describes how different aspects of fracture formation in concrete can be investigated using a combination of Acoustic Emission (AE) techniques, ultrasonic wave velocity imaging, and high resolution Computed Tomography (CT). Fracture formation and evolution were studied during shear failure of large reinforced concrete beams and compressive failure of concrete samples. AE analysis includes studying complex spatial and temporal fracture development that precedes shear failure. Predominant microcrack mechanisms were analyzed at different stages of fracture formation. CT images were used to investigate the influence of concrete microstructure on fracture topography. Combined AE and CT damage evaluation techniques revealed different aspects of fracture development, thus expanding our understanding of AE events and their mechanisms. These images show how aggregate particles influence fracture nucleation and development. An emphasis has been placed on the role of coarse aggregates during the interlocking of fracture surfaces at transferring shear stresses. Ultrasonic wave velocity and AE techniques have been applied to uniaxial compression tests of concrete with various aggregate sizes and strengths similar to that of the concrete beams. AE parameters, p-wave velocities, and stress-strain data have been analyzed concurrently to image damage evolution under compression. Influence of material composition on microcracking and material state changes during loading has been investigated in detail. The results of compressive tests were used as building blocks for developing realistic micromechanical numerical models of concrete. The models were designed using a distinct element code, where material is modelled through the combination of bonded particles. A number of procedures were developed to transfer the exact microstructure of material incorporating its visual representation into the model. The models’ behaviour has been verified against experimental data. It was shown that these models exhibit realistic micromechanical behaviour. The results of the experimental investigation of concrete fracturing were expanded by modelling more cases with aggregate size and strength variations. It was shown that geophysical imaging techniques, along with advanced micromechanical numerical modelling, can help us understand damage formation and evolution.

Keywords: acoustic emission
computed tomography
microcracks
fracture
concrete
aggregate interlock
ultrasonic wave velocity
aggregate size
shear failure
uniaxial compression
distinct element method
Advisor: Young, R. Paul
The Development and Usability Evaluation of a Clinical Decision Support Tool for Osteoporosis Disease Management

Osteoporosis is a major public health concern, affecting over 200 million people worldwide. There is valid evidence outlining how osteoporosis can be diagnosed and managed, but gaps exist between evidence and practice. Graham’s “Knowledge to Action” (KTA) process for knowledge translation and the Medical Research Council (MRC) framework for complex interventions were used to address these gaps. The first 4 KTA steps were collapsed into 3 phases of the PhD research plan. In PhD Phase 1, a systematic review was conducted to identify tools that facilitate decision making in osteoporosis disease management (DM). Results showed that few DM tools exist, but promising strategies were those that incorporated reminders and education and targeted physicians and patients. PhD Phase 2 used the findings from the systematic review and consultation with clinical and human factors engineering experts to develop a conceptual design of the tool. Multiple components targeted to both physicians and patients at the point of care, and which could be used as a standalone system or modifiable for integration with electronic health record systems were outlined. PhD Phases 3a and 3b were devoted to the assessment of the barriers to knowledge. In Phase 3a, a qualitative study of focus groups was conducted with physicians to identify attitudes and perceived barriers to implementing decision support tools in practice, and to identify the features that should be included in the design. Findings from 4 focus groups combined with aging research, and input from design and information experts were used to transform the conceptual design into a functional prototype. In Phase 3b, each component of the prototype was tested in 3 usability evaluation studies using an iterative, participant-centered approach to assess how well the prototype met end users’ needs. Findings from the usability study informed the final prototype, which is ready for implementation as part of the post PhD plan to fulfill the requirements of the remaining steps of the KTA and MRC frameworks.

Keywords: Knowledge translation
Clinical decision support systems
Osteoporosis
Family practice
Advisor: Straus, Sharon
Determining the Roles of the Intrinsic versus the Extrinsic Pathway in Regulating Neuronal Programmed Cell Death In Vivo

Programmed cell death (PCD) is a highly evolved mechanism of cellular suicide that is aberrantly activated following neural injury. Two fundamental PCD signaling pathways termed the extrinsic (caspase-8-mediated) and intrinsic (caspase-9-mediated) pathways, have been described. While each pathway is initiated by distinct cellular stimuli, both pathways culminate in the activation of downstream executioner caspases. Previous efforts to isolate the in vivo contribution of each pathway have been hindered by the embryonic lethality of casp8 and casp9 null mice. In the present study, I overcame this obstacle to directly assess the contribution of each pathway following two well-characterized forms of acute neural injury; excitotoxic destruction of CA1 pyramidal neurons, and the loss of motor neurons following facial nerve transection. To determine the role of caspase-8, I constructed several lines of mice in which caspase-8 was conditionally ablated within the relevant neuronal populations. The results obtained from these animals definitively demonstrate that caspase-8 is not required by either motor neurons or CA1 pyramidal neurons to undergo PCD following injury. Therefore, these findings have provided the first direct experimental evidence to counter the widely held dogma of caspase-8 as the central effector of death receptor-mediated signaling within neurons. With respect to the intrinsic pathway, several lines of evidence suggest that the apoptosome predominantly regulates the death of motor neurons. I tested this hypothesis by performing facial axotomies in mice containing a point mutation introduced (“knocked in”) into the genomic locus of cytochrome c which abolishes its ability to activate the intrinsic pathway. Homozygous cytochrome c knock-in mice displayed a significant enhancement in motor neuron survival in comparison to control littermates following injury. However, the level of motor neuron protection differed from that previously reported in mice either overexpressing anti-apoptotic or lacking pro-apoptotic members of the Bcl-2 family. Therefore, the results of this study directly demonstrate the influence of the apoptosome on injury-induced neuronal PCD isolated from upstream Bcl-2 family-mediated effects. In addition, my results have provided the first evidence that activation of the apoptosome is required for the release of apoptosis inducing factor (AIF) from the mitochondria of injured motor neurons in vivo.

Keywords: Neuronal Programmed Cell Death
Gene Knockout
Advisor: Henderson, Jeffrey T.
Neuroprotective Drug Delivery to the Injured Spinal Cord with Hyaluronan and Methylcellulose

Traumatic spinal cord injury (SCI) is a devastating condition for which there is no effective clinical treatment. Neuroprotective molecules that minimize tissue loss have shown promising results; however systemic delivery may limit in vivo benefits due to short systemic half-life and minimal passage across the blood-spinal cord barrier. To overcome these limitations, an injectable intrathecal delivery vehicle comprised of hyaluronan and methylcellulose (HAMC) was developed, and previously demonstrated to be safe and biocompatible intrathecally. Here, HAMC was determined to persist in the intrathecal space for between 4-7 d in vivo, indicating it as an optimal delivery system for neuroprotective agents to reduce tissue degeneration after SCI. HAMC was then investigated as an in vivo delivery system for two neuroprotective proteins: erythropoietin (EPO) and fibroblast growth factor 2 (FGF2). Both proteins demonstrated a diffusive release profile in vitro and maintained significant bioactivity during release. When EPO was delivered intrathecally with HAMC to the injured spinal cord, reduced cavitation in the tissue and significantly improved neuron counts were observed relative to the conventional delivery strategies of intraperitoneal and intrathecal bolus. When FGF2 was delivered intrathecally from HAMC, therapeutic concentrations penetrated into the injured spinal cord tissue for up to 6 h. Poly(ethylene glycol) modification of FGF2 significantly increased the amount of protein that diffused into the tissue when delivered similarly. Because FGF2 is a known angiogenic agent, dynamic computed tomography was developed for small animal serial assessment of spinal cord hemodynamics. Following SCI and treatment with FGF2 from HAMC, moderate improvement of spinal cord blood flow and a reduction in permeability were observed up to 7 d post-injury, suggesting that early delivery of neuroprotective agents can have lasting effects on tissue recovery. Importantly, the entirety of this work demonstrates that HAMC is an effective short-term delivery system for neuroprotective agents by improving tissue outcomes following traumatic SCI.

Keywords: Drug Delivery
Spinal Cord Injury
Spinal Cord Blood Flow
CT Imaging
Tissue Diffusion
Fibroblast Growth Factor 2
Erythropoietin
Injectable
Intrathecal
Poly(ethylene glycol)
PEGylation
Dynamic Contrast Enhancement
Advisor: Shoichet, Molly
Developmental Plasticity of Language Representation in Healthy Subjects and Children with Medically Intractable Epilepsy

This thesis includes four studies designed to improve the ability to predict and assess language representation in healthy children and/or individuals with neurological disorders arising in childhood. In the first study, the role of pathology type on interhemispheric plasticity of language was determined by comparing lateralization in children with developmental, acquired, and tumour pathologies. Findings from 105 consecutive intracarotid sodium amobarbital procedures were retrospectively analyzed, revealing no lateralization differences between pathology groups. In the second study, a novel verb generation paradigm and magnetoencephalography (MEG) were used to determine the spatial-temporal characteristics of language expression in healthy subjects (n = 12) and children with neurological disorders (n = 4). Time-frequency and differential beamformer analyses revealed low-beta event-related desynchronization (ERD) in the left inferior frontal lobe for verb generation. The paradigm was well-tolerated by all subjects. The third study involved assessment of expressive language lateralization in 25 healthy subjects, aged 5-18 years, using two novel MEG paradigms: covert picture naming and verb generation. Novel analyses permitted objective quantification of ERD lateralization on an individual basis. For both tasks, left lateralization of frontal lobe ERD tended to increase with advancing age. Findings suggest that adult-typical left lateralization emerges from an early bilateral language network in normal development. In the fourth study, frontal lobe ERD lateralization for naming and verb generation was characterized in 14 children and adolescents with neurological disorders. Novel analyses permitted objective assessment of individual scans at multiple contrast time windows. In several cases, rapid hemispheric shifts in predominant frontal lobe ERD were observed through the response period. On an individual basis, the assessment protocol showed promise for future use in a presurgical context. These studies serve to advance the understanding of normal paediatric language representation, and improve the ability to predict and assess language lateralization in individuals who have experienced early neurological insults.

Keywords: language
plasticity
development
epilepsy
Advisor: Smith, Mary Lou