VictorJuiz/thesis huggingface dataset:
Thermally Sprayed High Temperature Sandwich Structures: Physical Properties and Mechanical Performance
Keywords: Arc Spray
coating
materials selection
Metallic foam core
Sandwich Structure
thermal spray

Metallic foam core sandwich structures have been of particular interest for engineering applications in recent decades due to their unique physical and mechanical properties. One of the potential applications of open pore metallic foam core sandwich structures is in heat exchangers. An investigation of sandwich structures fabricated from materials suitable for application at high temperatures and in corrosive environments was undertaken in this project. A novel method for fabrication of metallic foam core sandwich structures is thermal spray deposition of the faces on the prepared surfaces of the metallic foam substrate. The objective of the current study was to optimize the twin wire arc spray process parameters for the deposition of alloy 625 faces with controllable porosity content on the nickel foam substrate, and to characterize the physical and mechanical properties of the sandwich structure. The experimental investigations consisted of microstructural evaluation of the skin material and the foam substrate, investigation of the effect of alloying on the mechanical and thermal properties of the nickel foam, optimization of the grit-blasting and arc spray processes, observation of mechanical properties of the alloy 625 deposit by tensile testing and evaluation of the overall mechanical properties of the sandwich structure under flexural loading condition. The optimization of arc spraying process parameters allowed deposition of alloy 625 faces with a porosity of less than 4% for heat exchanger applications. Modification of the arc spraying process by co-deposition of polyester powder enabled 20% porosity to be obtained in the deposited faces for heat shield applications with film cooling. The effects of nickel foam alloying and heat treatment on the flexural rigidity of the sandwich structures were investigated and compared with as-received foam and as-fabricated sandwich structures. Available analytical models were employed to describe the effect of constituentsâ mechanical properties on the overall mechanical performance of the sandwich structures. Finite element modeling using ANSYS Structural was used to simulate the behaviour of the sandwich structures in four-point bending. The analytical and simulation results were compared with the experimental results obtained from the flexural tests.
Scaling of Hybrid Wing-body-type Aircraft: Exploration Through High-fidelity Aerodynamic Shape Optimization
Keywords: Aerodynamic shape optimization
Exploratory optimization
Hybrid wing-body aircraft
Lifting fuselage aircraft

Unconventional aircraft configurations have the potential to reduce aviationâ s contribution to climate change through substantial reductions in fuel burn. One promising configuration which has received much attention is the hybrid wing-body (HWB). Due to the lack of design experience for unconventional configurations, high-fidelity design and optimization methods will be critical in their development. This thesis presents the application of a gradient-based aerodynamic shape optimization algorithm based on the Reynolds-averaged Navier-Stokes equations to the aerodynamic design of conventional tube-and-wing (CTW) and HWB aircraft. The optimal aerodynamic shapes and performance for a range of aircraft sizes including regional, narrow-body, midsize, and wide-body classes are found so as to characterize the aerodynamic efficiency benefits of the HWB configuration with respect to equivalent CTW designs. Trim-constrained drag minimization is performed at cruise, with a large design space of over 400 design variables. The smaller optimized HWBs, including the regional and narrow-body classes, while more aerodynamically efficient, burn at least as much fuel as to the equivalently optimized CTWs due to their increased weight, while the larger wide-body-class HWB has almost 11% lower cruise fuel burn. To investigate alternative configurations which may yield improved efficiency, exploratory optimizations with significant geometric freedom are then performed, resulting in a set of novel shapes with a more slender lifting fuselage and distinct wings. Based on these exploratory results, new lifting-fuselage configurations (LFCs) are designed. The slenderness of the LFC fuselage decreases with aircraft size, such that, for the largest class, the LFC reverts to a classical HWB shape. This new configuration offers higher aerodynamic efficiency than the HWBs, with the smaller classes seeing the largest benefit from the new configuration. This new lifting-fuselage concept offers 6% lower cruise fuel burn than the CTW in the regional class, and a marginal benefit in the narrow-body class. The effects of cruise altitude, stability requirements, and weight sensitivity are also examined.
Transport Phenomena in Drying Paint Films
Keywords: Diffusion Growth
Mass Transfer and Drying
Paint Defects
Particle Self-assembly
Surface-tension-driven instability
Two-phase Flow

Paint films with uniform thicknesses ranging from 150 to 820 µm were applied on stainless steel substrates using a model paint consisting of a resin dissolved in butanol. Test samples were cured in a natural convection oven at a temperature of 140°C. Photographs of the paint surface were taken during drying and the weight loss was measured. Cellular structures appeared on the paint surface, induced by surface tension-driven flows due to solvent concentration variations. For thin films (
Adaptation Mechanisms of Streptococcus mutans to Stresses Induced by Resin Composite Biodegradation By-products
Keywords: Biodegradation
BisHPPP
Dental composites
Secondary caries
Streptococcus mutans
Triethylene glycol

Resin composites are currently the most popular dental restorative materials. While providing several beneficial properties such as superior esthetics and excellent adhesive strength to dentin and enamel, resin composites undergo biological breakdown in the oral cavity that results in secondary/recurrent caries and reduced restoration longevity compared to amalgam. The breakdown of the resin-dentin interface by salivary and bacterial esterases generates biodegradation by-products (BBPs) including triethylene glycol (TEG) and bis-hydroxy-propoxy-phenyl-propane (BisHPPP). This chemical degradation contributes to gap formation between the restoration and the tooth, providing a path for microleakage of cariogenic microorganisms such as Streptococcus mutans, potentially resulting in recurrent/secondary caries, which is a major cause for resin composite restorations replacement. To test the hypothesis that BBPs activate signaling pathways that are involved in Streptococcus mutans pathogenicity and understand the molecular pathways that regulate the BBPsâ effects on cariogenic bacteria, this thesis quantitatively and mechanistically studied the effect of TEG or BisHPPP at clinically-relevant concentrations on the virulence properties of S. mutans UA159 in a relevant in vitro model. Quantitative real-time polymerase chain reaction showed up-regulation of seven dominant virulence-associated genes i.e. gtfB, gtfC, gbpB, comCDE and atpH, more significantly in biofilm vs. planktonic cells, only at cariogenic pH (5.5). Exposure of the constructed knock-out and complemented strains of S. mutans for the key regulatory genes, vicK and comC, to BBPs suggested these signalling pathways as potential mechanisms for up-regulation of the virulence-associated genes. S. mutans biofilm proteome analysis after exposure to TEG/BisHPPP confirmed activation of specific bacterial adaptation mechanisms such as biofilm formation and adhesion, acid tolerance, optimization of phosphotransferase system and stress-response pathways in response to BBPs. Microarray data were consistent with the proteomics findings for BisHPPP. Furthermore, both BBPs increased glucosyltransferases enzyme activity, involved in synthesizing exopolysaccharide glucan associated with the formation of cariogenic biofilms. This thesis provides significant insight into the adaptive response of S. mutans to the dental biomaterial-derived degradation products and elucidates the potential molecular mechanisms that could contribute in pathogenesis of secondary caries in resin composite restorations. It also provides a rationale for development of dental restorative materials that are more biostable and biocompatible.
Differentiating Questions from Statements: The Role of Intonation
Keywords: development
intonation
perception
prosody
question
speech

The most salient cues to yes/no questions and statements are rising and falling terminal pitch contours. Because young children readily differentiate rising from falling pitch contours, the presumption is that they can discern speakers’ questioning or declarative intentions from intonation alone. This thesis examined developmental changes in the use of intonation to identify questions and statements. In the first of three studies, participants from 5 years of age judged naturally produced utterances and low-pass filtered versions as questions or statements. Children correctly identified utterance type above chance levels and achieved adult accuracy levels at 9 years of age, highlighting younger children’s confusion about the links between intonation contours and pragmatic intentions. In the second study, participants from 8 years of age judged utterances with graded manipulations of terminal contours as questions or statements. Children’s question/statement judgments shifted more gradually than those of adults, reflecting greater uncertainty, but the location of the category shift was comparable across age. Adults' discrimination of utterance pairs was best for the pair that crossed the category shift, implying categorical perception of the intonation contours. In the final study, participants from 7 years of age judged the statement or question status of child- and adult-directed utterances in a gating task with words added incrementally. After limited exposure to the speaker’s voice, adults and children from 9 years of age correctly identified questions and statements from the initial word, demonstrating for the first time that English-speaking adults and children perceive pre-terminal cues to these utterance types. Identification was more accurate for child-directed than for adult-directed utterances, indicating that the former speech register exaggerates the distinctions between question and statements. Collectively, the findings reveal a protracted course of development for the questioning and declarative intentions signalled by intonation patterns and, more generally, for the pragmatic functions of intonation.
Characterizing the Motor Deficits in Children with Specific Language Impairment
Keywords: Developmental disorders
Language development
Motor learning
Procedural memory
School-aged children
Specific language impairment

The objective of this dissertation was to characterize the motor deficits in children with specific language impairment (SLI). This research was motivated by the hypothesis that the motor deficits provide a window into the underlying cause of SLI, which is currently unknown. The motor abilities of children with and without SLI were explored through a broad range of tasks across three experimental studies. The first study examined childrenâ s gross, fine, oral motor and speech motor skills. The second study investigated childrenâ s motor sequence planning and execution, adaptation and retention abilities. And the last study explored temporal aspects of the manual communicative gesture productions of children with SLI. The results of these studies revealed that children with SLI had significant difficulties with novel balance, fine limb and speech motor skills. At the processing level, children with SLI exhibited impaired fine motor sequence planning and execution, while adaptation and retention appeared to be unaffected. These procedural measures were also significantly correlated with performance on grammar and vocabulary measures. Finally, the temporal relationship between speech and communicative gesture was comparable between children with and without SLI. This profile of motor impairment in SLI and its association with language ability may be best explained by deficits in procedural learning. Future studies should examine whether procedural motor measures can supplement current diagnostic protocols of SLI and whether treatment approaches that target procedural learning capacity are more effective at treating the language, motor and cognitive deficits in SLI.
Temporal Transferability of Model Components within an Activity-Based Travel Demand Modelling Approach
Keywords: Activity-based models
Econometrics
Temporal transferability
Travel behaviour

Temporal transferability is one of the key and implicit conditions of developing travel behaviour models as these are developed for forecasting future levels of transport demand. Current travel demand modelling practices are focusing on the development of advanced models that better explain current behaviour rather than an emphasis on the ability of these models in forecasting. The importance of producing high temporal transferability of models should not be neglected as these models are used by planners and policy-makers to test policy decisions and to estimate future demands, which are critical inputs for infrastructure planning and maintenance. This research presents an investigation of the temporal transferability of activity generation process, scheduling process, and mode choice models. Three repeated cross-sectional household travel survey datasets collected in the greater Toronto and Hamilton area (GTHA) are used for the investigation. A multiple discrete-continuous extreme value model is used to develop an activity-travel generation model, and separate models are estimated for non-workers and workers. A Random utility maximization (RUM) based dynamic activity scheduling model is utilized to develop an activity-travel scheduling model for non-workers and workers separately. Heteroskedastic GEV model (HET-GEV) and HET-GEV model with scale parameter parameterized as a function of entropy are developed for commuting mode choice trips. Models are developed for individual years and then for the pooled data set of three cross-sectional years to develop a Meta model for each component. Individual year-specific models are used to increase knowledge about the temporal stability of different parameters of the model so that the Meta model could capture the non-linear evolution of some key parameters of the model. Different transferability indices are used to test temporal transferability of cross-sectional year-specific models and the Meta model. Results demonstrate an approach of effectively using multiple repeated cross-sectional datasets as pseudo panel data to develop Meta models to improve the temporal transferability of activity-based travel demand models.
Non-confidential Clinical Prediction with Summarized Data
Keywords: Cancer
Clustering
Heath Informatics
Intensive Care Unit
Regression Analysis
Summarized Data

This dissertation reports on a series of five studies that were motivated by the need to incorporate information about similar patients into clinical decision making. The studies examined questions relating to the feasibility of a tool that could identify similar patients in health data repositories, and then use the resulting patient types for prediction of unknown values in the health record for a current patient. The main question addressed in this dissertation was: how well do predictions based on summarized clusters match predictions based on the original (unsummarized) data in terms of accuracy? The motivation for using summarized prediction in this dissertation is that summarization of sufficiently large numbers of cases removes the privacy concerns typically associated with using individual data. After an introductory chapter which establishes the motivation for the research and the overall research strategy, each of the five following chapters presents a case study in the use of cluster analysis in secondary analysis of patient data. Chapters 2, 3 and 4 utilized (MIMIC II) intensive care data. A set of patient types was developed in chapter 2 and the accuracy of predictions made with summarized data based on patient types was assessed in chapter 3. Chapter 4 focuses on the role of feature extraction in clinical prediction and compares the method used in chapter 3 with some other methods such as the K-nearest Neighbor method. Chapters 5 and 6 utilized the (ICES) cancer data from the province of Ontario. A set of patient types was developed from the cancer data (in chapter 5) and in chapter 6 the accuracy of predictions made with summarized data, based on the set of cancer patient types, was evaluated. The dissertation concludes in the final chapter with a review of the contributions (both empirical and methodological) made in the research as well as a listing of the limitations of the research and future research prospects. The main finding of this research was that relatively accurate predictions can be made based on summarized patient data in a way that does not raise privacy concerns. A secondary result is that when accuracy in prediction is used to select a particular partition of the patients, the resulted patient types can be quite interpretable. The present results point the way towards improved clinical decision support tools, and, possibly, the development of generalized health data search engines.
Genetic and Epigenetic Crosstalk Define TP53-mediated Human Cancer Susceptibility
Keywords: Cancer susceptibility
DNA methylation
epigenetics
Li-Fraumeni Syndrome
miR-34A
TP53

Deregulation of epigenetic programming is crucial to tumorigenesis, yet the extent to which epigenetics plays a role in cancer susceptibility remains unclear. This work details systematic molecular investigations of the familial cancer predisposition syndrome, Li-Fraumeni Syndrome (LFS), to garner a better understanding of the role of epigenetics in cancer susceptibility in humans. LFS is a prototypical cancer susceptibility syndrome characterized by a 73-100% lifetime incidence of developing at least one malignancy in affected individuals. The majority of LFS cases are associated with inherited or de novo mutations in the TP53 gene, encoding the tumor suppressor protein, p53. This work reports the first genome-wide survey of DNA methylation in peripheral blood leukocytes from carriers of germline TP53 mutations, and reveals that TP53 mutation carriers harbor a distinct DNA methylation profile relative to non-carriers overall, and in subgroup analyses stratified by cancer diagnosis. Many TP53 mutation-associated differential methylation marks occur at previously characterized p53 transcription factor binding sites. In particular, striking hypomethylation of the miR-34A promoter, a known tumor suppressor in the p53 regulatory network, is detected in leukocytes from LFS patients in two independent cohorts. By contrast, miR-34A promoter hypermethylation is a recurrent epigenetic event in primary LFS tumors of various histologies and correlates with poor clinical outcome in patients with choroid plexus carcinomas. These findings suggest a role for miR-34A as an important tumor suppressor in LFS, and demonstrate that loss of miR-34A by somatic epimutation may comprise a step in neoplastic progression in this clinical context. Detailed molecular investigations to better understand the functional role of miR-34A in the background of mutant TP53 reveal that miR-34A is essential for cell viability and regulates a network of noncoding RNAs, including components of the minor spliceosome, as well as various long non-coding RNAs. The function of miR-34A in cell cycle states may be mediated by these transcriptional changes. Collectively, this work provides the first insights into the mechanisms by which germline TP53 mutations may confer cancer predisposition and implicates a novel gene, miR-34A, in the pathogenesis of TP53-associated human cancer susceptibility.
Characterizing the Effects of Extended Cannabis Abstinence on Cognitive Function in Patients with Schizophrenia and Non-psychiatric Controls with Cannabis Dependence
Keywords: Cannabis
Cognition
Schizophrenia

Background: While chronic cannabis use impairs cognition in controls, paradoxically, cannabis-using patients with schizophrenia demonstrate better cognitive function than non-using patients. It has been proposed that this relationship is driven by a higher functioning patient subgroup (trait effect) that is cognitively less impaired than their non-using counterparts. A caveat, however, is that most studies employed cross-sectional designs making it difficult to draw firm conclusions regarding causality. AIM: Therefore, we used a 28-day cannabis abstinence period to investigate the state-dependent effects of cannabis on key cognitive outcomes (e.g., HVLT, SDR, Digit Span) in cannabis dependent schizophrenia patients versus non-psychiatric controls. Hypothesis: We predicted that abstaining participants would experience improvements in working memory, and verbal memory and learning performance over time, and expected patients to have greater magnitude of change compared to controls. Method: Nineteen patients and 20 non-psychiatric male cannabis dependent participants underwent 28 days of cannabis abstinence. Cognition was assessed biweekly on Day 0, 14 and 28 using a comprehensive battery. Clinical symptoms were assessed weekly. Abstinence was encouraged using weekly therapy sessions and low cost contingency management confirmed by twice weekly urine assays. Results: Fort-two percent of patients and 55% of controls achieved end-point abstinence. This was biochemically verified by full cannabis elimination (Day28 urinary THC-COOH
Middle Aortic Syndrome and Renal Artery Stenosis: Disease Beyond the Arch
Keywords: Abdominal aorta
Aortic stenosis
Middle aortic syndrome
Renal artery stenosis
Renovascular hypertension
Vascular imaging

Background Middle aortic syndrome (MAS) is a rare childhood disease, often associated with renal artery stenosis (RAS). The etiology is unknown in most cases, but genetic and inflammatory causes have been described. Management of the associated hypertension can be medical, endovascular, or surgical, with variable success. Aims Our aims were to 1) evaluate management, and outcomes of MAS and/or RAS by etiology; 2) assess the peripheral vascular involvement and aortic disease; and 3) evaluate cardiac structure, function, and myocardial mechanics. Methods Aim 1: we conducted a systematic review of 630 MAS cases, and a retrospective cohort study of 93 children with MAS and/or RAS managed at the Hospital for Sick Children (HSC). Aim 2: a cross-sectional prospective study of 35 children with MAS and/or RAS was initiated at HSC (2014-2016). Carotid intima-media thickness (CIMT) and pulse wave velocity (PWV) were assessed using B-mode ultrasound and applanation tonometry. Aim 3: two-dimensional echocardiography and speckle-tracking echocardiography were used to assess left ventricular mass (LVM), diastolic function (E/a ratio) and myocardial strain. All cardiovascular measurements were compared to age, sex, and body surface area- matched healthy children. Results Of 630 cases in the literature, 70% had RAS, and the aortic disease was confined to the peri-renal aorta. Of 93 children managed at HSC, 70% received endovascular or surgical intervention, with a higher risk of intervention in children with unknown disease compared to those with genetic and inflammatory causes (HR=3, 95% CI [2,6]). Hypertension persisted in 65% of all patients for 2 [0.4-5] years after management. CIMT was increased in children with MAS and/or RAS compared to controls (0.54Âą0.10 vs. 0.44Âą0.05 mm, p