VictorJuiz/thesis huggingface dataset:
Perfuorocarboxylate Isomer Aanalysis as a Tool for Source Elucidation
Keywords: perfluorocarboxylate
isomers

Perfluorocarboxylates (PFCAs) are a class of anthropogenic compounds ubiquitously found in the environment. PFCAs and their precursors are largely manufactured by electrochemical fluorination (ECF) or telomerization. ECF products are mixtures of isomers with linear (70-80%) and branched perfluoroalkyl moiety. Telomerization does not produce isomer mixtures and is predominantly n-perfluorocarbons. This thesis examined the environmental fate and disposition of PFCAs from a relevant and novel perspective of industrial isomer signature. Potential influences of physical and biological properties of isomers on the environmental PFCA isomer pattern were investigated. Branched isomers were more water soluble than n-isomer, however, KOW did not indicate any appreciable differences among isomers. It is possible that the similarity in KOW is due to a balancing effect between elevated activity coefficients in both water and n-octanol. In fish and rats, the major branched isomers of ECF PFOA were eliminated faster than n-isomer. In comparison, PFOS isomer pharmacokinetics were indistinguishable. These findings highlight the need to understand underlying mechanisms mediating PFCA and PFOS isomer pharmacokinetics which may constrain extrapolation from animal-based models to humans. Environmental monitoring revealed PFCA isomers in both abiotic and biotic environment, in temperate regions and remote Arctic. Branched PFOA isomers were consistent with ECF production. In temperate regions, industrially produced ECF PFOA was expected to be a major source of these isomers, given its legacy and volume of production. In the Arctic, PFOA isomers consistent with an ECF signature were attributed to ECF perfluorooctylsulfonamides which likely undergo long range atmospheric transport and atmospheric reactions. The major difference in ECF signature between remote and temperate regions is the presence of ECF PFNA isomers compared to their absence in the Arctic. ECF PFNA is an impurity in ECF PFOA, comprising 0.2%. Input from a linear source, such as fluorotelomer compounds, was also suggestive as both PFOA and PFNA were >95% linear, much more than in technical ECF. Furthermore, longer chain ECF impurities do not account for the PFNA, PFDA, PFUnA, etc. in the Arctic.
The Use of Stereoscopic Cues in the Perception of Noise Masked Images of Natural Objects
Keywords: Binocular summation
Stereopsis
Stereoscopic vision
Visual recognition
Detection
Categorization
Identification

When seen through a stereoscope, a Gabor pattern (a Gaussian enveloped sinusoid) that is masked by visual noise is more readily detectable when it appears in front of or behind the noise than when it is embedded in the noise itself. The enhanced visibility brought about by stereo cues is referred to as binocular unmasking. In this work, we investigated whether binocular unmasking may also occur with visual objects more complex than simple Gabor patterns, and with tasks more demanding than detection. Specifically, we examined the effects of binocular unmasking in the detection, categorization, and identification of noise masked images of natural objects. We observed the occurrence of binocular unmasking in all three tasks. However, the size of this effect was greater for detection performance than for categorization or identification performance; the latter two benefited to the same extent by the availability of stereoscopic cues. We argue that these results suggest that low level stereoscopic depth cues may play a helpful role, not only in simple detection tasks with psychophysical stimuli, but also in the perception of complex stimuli depicting natural objects.
Stimulus-responsive Microgels: Design, Properties and Applications
Keywords: microgels
drug delivery
nanotechnology
biomedical engineering
stimulus-responsive
gold nanorods
polymers
materials chemistry
polyampholyte
nanoparticles

Materials science today is a multidisciplinary effort comprising an accelerated convergence of diverse fields spanning the physical, applied, and engineering sciences. This diversity promises to deliver the next generation of advanced functional materials for a wide range of specific applications. In particular, the past decade has seen a growing interest in the development of nanoscale materials for sophisticated technologies. Aqueous colloidal microgels have emerged as a promising class of soft materials for multiple biotechnology applications. The amalgamation of physical, chemical and mechanical properties of microgels with optical properties of nanostructures in hybrid composite particles further enhances the capabilities of these materials. This work covers the general areas of responsive polymer microgels and their composites, and encompasses methods of fabricating microgel-based drug delivery systems for controlled and targeted therapeutic applications. The first part of this thesis is devoted to acquainting the reader with the fundamental aspects of the synthesis, functionalization and characteristic properties of stimulus-responsive microgels constructed from poly(N-isopropylacrylamide) (poly(NIPAm)) and other functional comonomers. In particular, the role of electrostatics on the swelling-deswelling transitions of polyampholyte microgels upon exposure to a range of environmental stimuli including pH, temperature, and salt concentration are discussed. The templated synthesis of bimetallic gold and silver nanoparticles in zwitterionic microgels is also described. The latter part of this thesis focuses on the rational development of microgel-based drug delivery systems for controlled and targeted drug release. Specifically, the development of a biofunctionalized, pH-responsive drug delivery system (DDS) is illustrated, and shown to effectively suppress cancer cells when loaded with an anticancer agent. In another chapter, the design of tailored hybrid particles that combine the thermal response of microgels with the light-sensitive properties of gold nanorods to create a DDS for photothermally-induced drug release is discussed. The photothermally-triggered volume transitions of hybrid microgels under physiological conditions are reported, and their suitability for the said application evaluated. In another component of this work, it is explicitly shown that electrostatic interactions were not needed to deposit gold nanorods on poly(NIPAm)-derived particles, thereby eliminating the need for incorporation of charged functional groups in the microgels that are otherwise responsible for large, undesirable shifts and broadening of the phase transition.
Do Regional Models Matter? Resource Allocation to Home Care in the Canadian Provinces of Prince Edward Island, Nova Scotia & New Brunswick
Keywords: Resource Allocation
Home Care
Health Care Restructuring
Canadian Health Reform
Regionalization

Proponents of Canadian health reform in the 1990s argued for regional structures, which enables budget silos to be broken down and integrated budgets to be formed. Although regionalization has been justified on the basis of its potential to increase home care resources, political science draws upon the scope of conflict theory, which instead suggests marginalized actors, such as home care, may be at risk of being cannibalized in order to safeguard the interests of more powerful actors, such as hospitals. Prince Edward Island, Nova Scotia, and New Brunswick, constitute a natural policy experiment. Each has made different decisions about the regionalization model implemented to restructure health care delivery. The policy question underpinning this research is: What are the implications of the different regional models chosen on the allocation of resources to home care? Provincial governments are at liberty to fund home care within the limits of their fiscal capacity and there are no federal terms and conditions which must be complied with. This policy analysis used a case comparison research design with mixed methods to collect quantitative and qualitative data. Two financial outcomes were measured: 1) per capita provincial government home care expenditures and 2) the home care share of provincial government health expenditures. Hospital data was used as a comparator. Qualitative data collected from face-to-face, semi-structured interviews with regional elite key informants supplemented the expenditure data. The findings align with the scope of conflict theory. The trade-off between central control and local autonomy has implications for these findings: 1) home care in Prince Edward Island increased it share from 1.6% to 2.2% of provincial government health spending; 2) maintaining central control over home care in Nova Scotia resulted in an increase in its share from 1.4% to 5.4%, and 3) in New Brunswick, home care share grew from 4.1% to 7.6%. Inertia and entrenchment of spending patterns was strong. Health regions did not appear to undertake resource reallocation to any great extent in either Prince Edward Island or New Brunswick. Resource reallocation did occur in Nova Scotia where the hospital share of government spending went down and was reallocated to home care and nursing homes. But, Nova Scotia is the only province of the three in which home care was not regionalized. Regional interests in maintaining existing levels of in-patient hospital beds was clearly a source of tension between the overarching policy goals formulated for health reform by the provincial governments and the local health regions.
Threshold Phenomena in Random Constraint Satisfaction Problems
Keywords: computer science
phase transition
constraint satisfaction
threshold phenomena
random graphs
random SAT
algorithms
satisfiability
DPLL
random structures

Despite much work over the previous decade, the Satisfiability Threshold Conjecture remains open. Random k-SAT, for constant k >= 3, is just one family of a large number of constraint satisfaction problems that are conjectured to have exact satisfiability thresholds, but for which the existence and location of these thresholds has yet to be proven. Of those problems for which we are able to prove an exact satisfiability threshold, each seems to be fundamentally different than random 3-SAT. This thesis defines a new family of constraint satisfaction problems with constant size constraints and domains and which contains problems that are NP-complete and a.s.\ have exponential resolution complexity. All four of these properties hold for k-SAT, k >= 3, and the exact satisfiability threshold is not known for any constraint satisfaction problem that has all of these properties. For each problem in the family defined in this thesis, we determine a value c such that c is an exact satisfiability threshold if a certain multi-variable function has a unique maximum at a given point in a bounded domain. We also give numerical evidence that this latter condition holds. In addition to studying the satisfiability threshold, this thesis finds exact thresholds for the efficient behavior of DPLL using the unit clause heuristic and a variation of the generalized unit clause heuristic, and this thesis proves an analog of a conjecture on the satisfiability of (2+p)-SAT. Besides having similar properties as k-SAT, this new family of constraint satisfaction problems is interesting to study in its own right because it generalizes the XOR-SAT problem and it has close ties to quasigroups.
Making Visible the Invisible: Dual Language Teaching Practices in Monolingual Instructional Settings
Keywords: Second language education
Literacy and bilingualism
Linguistic diversity
Heritage languages in the curriculum

This dissertation documents the work of two teacher collaborators who brought a focus on linguistic and cultural diversity into their literacy teaching even while teaching in English medium schools. The research was carried out during eighteen months utilizing collaborative case study methodology in conjunction with two teachers in highly multilingual and multicultural public elementary schools in the Greater Toronto Area (GTA). This study explores the pedagogical possibilities that are made available by teaching for transfer and highlights the resource that students’ linguistic diversity can be even when the instructional setting is monolingual. The dual language literacy pedagogies of the two teachers provide the basis for an analysis of the paths for knowledge construction and identity development that were made available for students through this work. I examine the role that teacher identity and societal influences play in enabling or constraining a redefinition of literacy for the increasingly globalized context of schools. The image of the child, of literacy and of bilingualism projected by the work of the two participating teachers shape the analysis of their identity and role definition as educators. By examining teaching practices that integrate students’ linguistic and cultural identities into the fabric of the literacy curriculum several themes are considered: (a) the role of teacher identity and choice in creating learning contexts that draw on students’ interests and prior knowledge, (b) the link between student engagement and a classroom ecology that values students’ identities and, (c) the different types of knowledge that are generated in the process of participating in the dual language literacy work. Results suggest that students were able to utilize their first language skills in the service of learning English. They also experienced a renewed motivation to extend their first language skills into the sphere of literacy as a result of its affirmation within the classroom. In the case of both first and second language development, students’ ability to engage cognitively and affectively in their literacy work was heightened by virtue of the integration of their language and culture into the curriculum.
Impact Velocity, Almen Strip Curvature and Residual Stress Modelling in Vibratory Finishing
Keywords: Vibratory Finishing
Residual Stress
Almen Strip
Plate Bending
Impact
Peen Forming
Shot Peening

The surface-normal impact velocity distributions, impact frequencies and impact power per unit area were measured using a force sensor in a vibratory finisher for two types of spherical media. These parameters control the degree, rate and character of plastic deformation of a workpiece surface in vibratory finishing. The force sensor was also used to quantify the effect of media type, finisher amplitude, and location within the finisher on the probability distribution of the particle impact velocity normal to the workpiece. It was found that reducing the total media mass in the finisher and moving closer to the wall resulted in a more aggressive process. It was also found that contacts occured periodically within time periods that corresponded to the finisher’s driving frequency. The Almen system was adapted to a vibratory finishing process to characterize the effect of varying process parameters for the purposes of process development and control. Saturation curves for two types of aluminum Almen strips were obtained by finishing at two distinct conditions. Comparison with the normal contact forces and effective impact velocities, measured for both these conditions, provided insight into the mechanics of the vibratory finishing process. An electromagnetic apparatus was constructed to simulate the normal impacts in the vibratory finisher. It was found that surface-normal impacts at velocities comparable to the higher range in the vibratory finisher produced Almen saturation curves similar to those created in the vibratory finisher. This provided support for the modeling approximation of treating all contact events in a vibratory finisher as effective surface-normal impacts, and the accuracy of the effective impact velocity measurement. A model of the process by which Almen strips were plastically deformed by media impacts in vibratory finishing was presented. The motivation was to extend the use of Almen strip measurements as a means of characterizing vibratory finishing through an improved understanding of the process parameters that controlled time-dependent curvature development. Two thicknesses of Almen strip were tested for two finishing conditions. The quantitative agreement between the model saturation curves and the experimental curves was fair, although the overall trends were predicted very well.
Usage and Non-usage Behaviour of eHealth Services Among Chinese Canadians Caring for a Family Member with Dementia
Keywords: ehealth
health informatics
dementia
family caregiving
Chinese
Internet
caregiver support
information behaviour
technology acceptance
health service utilization
attrition
mixed methods design
cultural beliefs
social support
occupational therapy
social work

Background: Information Communication Technologies (ICT)-mediated support can reduce family caregiver burden and may bridge service gaps caused by time constraints and language or cultural barriers. (Non)-usage behaviour can be explained using Andersen’s Behavioural Model of Health Service Utilization, Venkatesh’s Unified Theory of Use and Acceptance of Technology, Eysenbach’s Law of Attrition, and Wilson’s and Chatman’s Information Behaviour Theories. Purpose: This study aimed to describe and explain (non)-usage behaviour of ehealth services among Chinese caregivers. Method: This two-phase study used a mixed methods design involving 46 Chinese caregivers who cared for a family member with dementia. Usability of the ICT tools designed in the study was tested. Phase I participants (N=28) had access to a bilingual information site and personalized email support from professionals. Phase II participants (N=18) were randomized to use one of three enhanced features. Pre- and post-intervention data were collected, and qualitative interviews were conducted. Results: The Phase I ICT tools supported the core functions without major usability issues. Perceived efforts to use the ICT-mediated services influenced the consent decisions of Phase I caregivers (p=.036). Caregivers initiated service earlier if they had a higher acceptance of the service (p=0.017). Frequent users of email support experienced a decline of perceived burden compared with an escalation of perceived burden by non-users (p=0.023). An older age, greater caregiving competence, and lower English or computer proficiency explained non-usage behaviour. Requirements were identified to enhance the Phase I ICT tools. In Phase II, a test of three enhanced features showed there was no major usability issue. The intervention study found the enhanced features did not influence email use as hypothesized. Qualitative analysis showed usage patterns were explained by caregiver needs, caregiving beliefs, personal capacity, social support, ICT factors, and style of use. Non-users preferred Chinese to English compared with users (p=0.046). Integrating the theories and empirical findings, three concepts were developed to explain (non)-usage behaviour: usage in context, usage paths, and stages of use. Conclusion: Usage and non-usage behaviour can be explained by the service needs in the caregiving context, the use of non-ICT-mediated resources, and the access barriers to Internet use. Use of ICT-based support can be beneficial to caregivers if they do not drop out of the service.
Modeling Injection and Ignition in Direct Injection Natural Gas Engines
Keywords: Natural Gas Engine
Modeling
Direct Injection
Ignition
CFD
Alternative Energy
Glow Plug

With increasing concerns about the harmful effects of conventional liquid fossil fuel emissions, natural gas has become a very attractive alternative fuel to power prime movers and stationary energy conversion devices. This research studies the injection and ignition numerically for natural gas (mainly methane) as a fuel applied to diesel engine. Natural gas injector and glow plug ignition enhancement are two of the most technical difficulties for direct injection natural gas engine design. This thesis models the natural gas injector, and studies the characteristics of the internal flow in the injector and natural gas jet in the combustion chamber during the injection process. The poppet valve model and pintle valve model are the first reported models to simulate the natural gas injector to improve the traditional velocity and pressure boundary conditions. This thesis also successfully models the glow plug assisted natural gas ignition and combustion processes by developing a glow plug discretized model and a novel virtual gas sub-layer model. Glow plug discretized model can describe the transient heat transfer, and adequately represents the thin layers of heat penetration and the local temperature difference due to the cold gas jet impingement. The virtual gas sub-layer model considers complicated physical processes, such as chemical reaction, heat conduction, and mass diffusion within the virtual sub-layers without significantly increasing computational time and load. KIVA-3V CFD code was chosen to simulate the fluid flow. Since the KIVA-3V is designed specifically for engine research application with conventional liquid fuels, many modifications have been implemented to facilitate this research.
Information in Financial Markets
Keywords: information asymmetry
leading
productivity
asset pricing

This thesis studies information in financial markets from three perspectives: the role of information asymmetry in alleviating dividend payers’ seasoned equity offering (SEO) announcement returns, the leading behavior of equity analysts who collect and process information, and the pricing of productivity-related information. More specifically, Chapter 1 studies whether the market reacts less negatively to dividend payers’ SEO announcements. Using US data from 1975 to 2002, I find that prior to SEO announcement dates, dividend payers have less information asymmetries than non-dividend payers. This difference was not large before the mid-1980s, but increased dramatically since then. This finding, together with the disappearing dividend puzzle documented in Fama and French (2001), suggests that a firm’s dividend status was not an important signal for SEOs prior to the mid-1980s, but became important since then. The market reacts less negatively to dividend payers’ SEO announcements since the mid-1980s. Chapter 2 studies equity analysts’ leading behavior in equity recommendations. I develop a measure of leading recommendations based on the observation that other recommendations move towards those of the leader. I find that analysts who are more likely to lead are past leaders, past All-American stars, analysts from large brokerage houses, and analysts with fewer recommendations. I find that the market reacts more strongly to recommendations of leaders and leaders are less likely to be terminated from their jobs. Chapter 3 examines the link between productivity and the cross-section of security returns. The CAPM and CCAPM have had problems finding empirical validations. In contrast, by creating factor mimicking portfolios with respect to productivity, I introduce a stock market factor that mimics the driving force behind the CCAPM. First, I find that the productivity factor affects the overall market return and that on average it contributes 0.75 to 2.41 percent annually, for the range of productivity factors I construct. Further, I show that productivity is priced even when the market excess return and factors based on size and book-to-market are included in standard asset pricing tests. However, the market excess return and the book-to-market factor still explain asset returns.