VictorJuiz/thesis huggingface dataset:
Vaporized Perfluorocarbon Droplets as Ultrasound Contrast Agents

Microbubble contrast agents for ultrasound are widely used in numerous medical applications, both diagnostic and therapeutic. Due to their size, similar to that of red blood cells, microbubbles are able to traverse the entire vascular bed, enabling their utilization for applications such as tumour diagnosis. Vaporizable submicron droplets of liquid perfluoro- carbon potentially represent a new generation of extravascular contrast agents for ultrasound. Droplets of a few hundred nanometers in diameter have the ability to extravasate selectively in regions of tumour growth while staying intravascular in healthy tissues. Upon extravasation, these droplets may be vaporized with ultrasound and converted into gas bubbles. In this thesis we argue that vaporized submicron perfluorocarbon droplets possess the necessary stability and acoustic characteristics to be potentially applicable as a new gener- ation of extravascular ultrasound contrast agents. We examine, separately, the ultrasound conditions necessary for vaporization of the droplets into microbubbles, the size and stability of these bubbles following vaporization, on timescales ranging from nanoseconds to minutes, and the bubbles’ acoustic response to incident diagnostic ultrasound. We show that submicron droplets may be vaporized into bubbles of a few microns in diameter using single ultrasound pulse within the diagnostic range. The efficiency of conversion is shown to be on the order of at least 10% of the exposed droplets converting into stable microbubbles. The bubbles are shown to be stabilized by the original coating material encapsulating the droplet precursors, and be stable for at least minutes following vaporization. Finally, vaporized droplets are shown to be echogenic, with acoustic characteristics comparable to these of the commercially available ultrasound contrast agents. The results presented here show that vaporized droplets possess the necessary stability properties and echogenicity required for successful application as contrast agents, suggesting potential for their future translation into clinical practice.

Keywords: ultrasound
contrast agents
perfluorocarbon droplets
vaporization
microbubbles
nonlinear imaging
medical imaging
Advisor: Burns, Peter N.
Computer Vision-based Solution to Monitor Earth Material Loading Activities

Large-scale earthmoving activities make up a costly and air-polluting aspect of many construction projects and mining operations, which depend entirely on the use of heavy construction equipment. The long-term jobsites and manufacturing nature of the mining sector has encouraged the application of automated controlling systems, more specifically GPS, to control the earthmoving fleet. Computer vision-based methods are another potential tool to provide real-time information at low-cost and to reduce human error in surface earthmoving sites as relatively clear views can be selected and the equipment offer recognizable targets. Vision-based methods have some advantages over positioning devices as they are not intrusive, provide detailed data about the behaviour of each piece of equipment, and offer reliable documentation for future reviews. This dissertation explains the development of a vision-based system, named server-customer interaction planner (SCIT), to recognize and estimate earth material loading cycles. The SCIT system consists of three main modules: object recognition, tracking, and action recognition. Different object recognition and tracking algorithms were evaluated and modified, and then the ideal methods were used to develop the object recognition and tracking modules. A novel hybrid tracking framework was developed for the SCIT system to track dump trucks in the challenging views found in the loading zones. The object recognition and tracking engines provide spatiotemporal data about the equipment which are then analyzed by the action recognition module to estimate loading cycles. The entire framework was evaluated using videos taken under varying conditions. The results highlight the promising performance of the SCIT system with the hybrid tracking engine, thereby validating the possibility of its practical application.

Keywords: Construction Management
Computer Vision
Automated Data Collection
Equipment Productivity
Advisor: McCabe, Brenda
Truth, Justification, and Literary Merit

This thesis develops and defends a new version of an old view known as literary cognitivism, which holds that the merit of a literary work as such sometimes depends on its cognitive merit. The newness of my view lies in the way it recommends we think about the cognitive merits of a literary work as they relate to its literary merits. Whereas some cognitivists identify the cognitive merit of a literary work with the truth of its themes and others with its capacity to provide certain non-propositional forms of knowledge, I propose that the cognitive dimension most relevant to literary value is the extent to which it provides certain forms of justification for its themes. In particular, I emphasize two ways in which a literary work can justify its themes: one, by providing evidence that its themes are the products of an intellectually virtuous mind and, two, by expressing its themes within a richly coherent framework of beliefs. I argue that the literary-evaluative significance of these two forms of justification is implicit, in the first case, in literary critical judgments that refer to a work’s didacticism, and, in the second case, in judgments that refer to a work’s thematic coherence. Insofar as it bears on these sources of justification, I contend, the truth or falsity of some non-thematic propositions can be relevant to literary value, though truth is generally not relevant at the thematic level.

Keywords: aesthetics
philosophy of literature
Advisor: Hurka, Amy Mullin Tom
Direct and Indirect Sources of Human Exposure to Perfluorinated Carboxylates: Investigating the Significance of Perfluorinated Carboxylate Reactive Precursor Metabolites

Perfluorinated carboxylates (PFCAs) are persistent and ubiquitous in the environment. Humans are exposed to PFCAs through direct and indirect sources, although the relative importance of each is uncertain. Direct sources of PFCAs have been attributed to two primary fluorochemical manufacturing processes: electrochemical fluorination (ECF) and telomerization. A focus of this thesis was to elucidate an additional direct source of PFCAs resulting from the direct fluorination of polyolefin materials. High density polyethylene bottles with varying levels of fluorination were observed to contain significant amounts of PFCAs, particularly those with carbon chain-lengths ≤ C6, marking an unexplored source of PFCA exposure. PFCAs are also produced indirectly from the biotransformation of fluorotelomer-based compounds, such as polyfluoroalkyl phosphate esters (PAPs) and fluorotelomer alcohols (FTOHs). During this transformation process, two predominant classes of metabolic intermediates are formed: the fluorotelomer unsaturated aldehydes (FTUALs) and the fluorotelomer unsaturated carboxylic acids (FTUCAs). Another focus of this thesis was to examine the reactivity of FTUALs and FTUCAs with endogenous nucleophiles such as glutathione (GSH), select amino acids, and model proteins. FTUALs formed adducts with all nucleophiles examined, where those having shorter carbon chain lengths (i.e. 6:2 and 8:2 FTUAL) were more reactive than longer carbon chains (i.e. 10:2 FTUAL). By contrast, FTUCAs had comparably limited reactivity; although FTUCAs showed mild reactivity with GSH, they did not react with any other nucleophiles. In vitro and in vivo experiments were carried out to determine the extent of protein binding formed from the biotransformation of fluorotelomer-based compounds, including the 8:2 FTOH and the 6:2 PAP diester. A significant portion of these biotransformations yielded covalent protein binding at nmol/mg protein concentrations. Protein adducts were observed predominantly in rat liver and also in plasma and kidney. The formation of reactive intermediates may be toxicologically important through protein deactivation. Cellular toxicity of FTUALs was significantly higher compared to PFCAs and the acid metabolic intermediates (i.e. FTUCAs). The EC50 values calculated from dose-response incubations were dependant on chain length and functional group. The work in this thesis examined an unexplored consequence of indirect exposure to PFCAs, potentially impacting the relative importance of PFCA exposure sources.

Keywords: Environmental Chemistry
Perfluorinated Carboxylates
Fluorotelomer
Reactivity
Biotransformation
Persistent
Advisor: Mabury, Scott A.
Towards a Structural and Methodological Improvement of Eutrophication Modelling

The credibility of the scientific methodology of mathematical models and their adequacy to form the basis of public policy decisions has frequently been challenged. Skeptical views of the scientific value of modelling argue that there is no true model of an ecological system, but rather several adequate descriptions of different conceptual basis and structure. The purpose of this work was to first advance the Bayesian calibration of process-based models for guiding the water quality criteria setting process in Hamilton Harbour, Ontario, Canada. The analysis suggests that the water quality targets for total phosphorus and chlorophyll a concentrations will likely be met, if the recommendation for phosphorus loading at the level of 142 kg day-1 is achieved. My dissertation also examines how the Bayesian approach can effectively support the decision making process by synthesizing the predictions of different models developed for the same system. The model averaging approach consolidates the finding that the existing total phosphorus goal is most likely unattainable. The discrepancy between the chlorophyll a predictions of the two models pinpoints the need to delve into the dynamics of phosphorus in the sediment-water column interface. This work also aims to examine statistical formulations that explicitly accommodate the covariance among the process error terms for various model endpoints. The analysis suggests that the statistical characterization of the model error can be influential to the inference drawn by a modelling exercise. Finally, my dissertation challenges the capacity of the ecological foundation of eutrophication models to predict the role of nutrient regeneration. It shows that the recycled nutrients can be significant drivers in low as well as in high-productivity ecosystems depending on the period of the year examined. My dissertation also discusses several prescriptive guidelines that should be helpful towards a structural and methodological improvement of eutrophication modelling.

Keywords: Eutrophication Modelling
Bayesian
Advisor: Arhonditsis, George
Evaluating the Greenhouse Gas Mitigation Potential and Cost-competitiveness of Forest Bioenergy Systems in Ontario

Recent literature has recommended that life cycle assessments (LCA) of forest bioenergy supply chains consider the impact of biomass harvest on ecosystem carbon stocks as well as the net emissions arising from combustion of various forms of biofuels compared with reference fossil fuel systems. The present study evaluated the magnitude and temporal variation of ecosystem C stock changes resulting from harvest of roadside residues and unutilized whole trees for bioenergy. The Carbon Budget Model (CBM-CFS3) was applied to the Gordon Cosens Forest, in northeastern Ontario, along with the Biomass Opportunity Supply Model (BiOS-Map), for cost analysis of different types of biomass comminution. Natural gas (NG) steam and electricity, grid electricity, and coal electricity reference systems were analyzed for a pulp and paper mill. The findings showed that the forested landscape becomes a net sink for carbon following the 20th year of roadside residue harvest, compared to whole-tree harvest, where the forested landscape remained a net source of carbon over the entire 100 year rotation. The cumulative ecosystem carbon loss from whole-tree harvest was 11 times greater compared to roadside residue harvest. BiOS-Map analysis suggested that due to technical and operational limits, between 55%-59% and 16%-24% of aboveground biomass was not recovered under roadside residue and whole-tree harvest respectively. The cost of delivering roadside residues was estimated at $52.32/odt–$57.45/odt, and for whole trees $92.63/odt–$97.44/odt. The Life Cycle Assessment (LCA) analysis showed break-even points of 25, 33 and 6 years for roadside residues displacing NG steam, NG electricity, and coal, respectively. No GHG reduction was achieved when forest biomass was used to displace grid electricity that is generated in Ontario. Whole-tree bioenergy resulted in no GHG reduction for NG displacement, and a break-even point of 70-86 years for coal. A net GHG reduction of 67% and 16% was realized when roadside residues and whole trees were used to displace coal, compared to 45% and 38% when roadside residues were used to displace NG steam and NG electricity, respectively. Therefore, it is recommended that bioenergy deployment strategies focus on the utilization of roadside residues, if the main goal is GHG mitigation.

Keywords: renewable energy
bioenergy
greenhouse gas emissions
carbon accounting
life cycle assessment
fossil fuels
natural gas
electricity
harvest operations
supply chain
Ontario
sustainable management
BiOS-Map
CBM-CFS3
GHGenius
cost
coal
climate change
biomass
forest residues
Gordon Cosens Forest
boreal forest
Advisor: Smith, Tat
Weather on Substellar Worlds: A Study of Clouds, Variability and Binarity at the L/T Transition

A study of clouds and variability in brown dwarf atmospheres is presented, with a focus on understanding the mechanism by which condensate clouds are dissipated at the transition between L and T spectral types. The results of a large J-band variability survey of over 60 mid-L to T dwarfs, and related observations are presented. We find statistically significant evidence (at the 95% confidence level) for an increase in large amplitude variability (peak to peak variations larger than 2%) within the L/T transition (L9-T3.5 spectral types), suggesting that the disruption of dust clouds by weather phenomena may contribute to the rapid decline in condensate opacity and J-band brightening observed to occur in this regime. Alternatively, the large amplitude variability observed could be the result of increasing contrast between discrete cloud features and the underlying atmosphere, rather than the development of cloud holes. We highlight the discovery of a T dwarf with 26% variability, and provide a detailed comparison with atmosphere models in order to infer the nature of cloud features responsible. Results are consistent with both the presence of thick storm features or cloud holes in our target's atmosphere, but are inconsistent with the presence of magnetic spots. Supporting work related to clouds in L dwarf atmospheres, and the L/T transition binary fraction is presented. From studying an unusually blue L-dwarf companion to a nearby M-dwarf star we infer that thin or patchy condensate clouds, rather than low metallicity and/or high surface gravity, are most likely responsible for its peculiar colors. The discovery of significant variability for a different blue L dwarf in our large variability survey provides further evidence for this hypothesis. Finally, combining our own high contrast imaging observations for 8 L/T transition targets with previous results we infer a resolved L/T transition binary fraction of 14(+7-6)%, consistent with that inferred for the general brown dwarf population. This latter result suggests that the L/T transition sample is not highly contaminated by unresolved multiples.

Keywords: brown dwarfs
Advisor: Jayawardhana, Ray
The Construction of Masculinity in Propertius

The gendered characterization of the Propertian lover-poet does not fit comfortably into either the role of a traditionally masculine elite male Roman or that of an effeminate elegiac lover. This dissertation argues for a lover-poet whose gender role draws on and reacts to elements from both of these pre-existing roles with the end result of a character that disidentifies with Roman gender roles and exists outside of the binary oppositions that they provide. The lover-poet’s characterization is intimately bound to that of his elegiac puella, usually identified in the poetry as Cynthia, and as such the focus of this dissertation is on the poems in which the lover-poet and Cynthia interact. Propertius explores tensions inherent in the gendered roles and relationships of elegy through his exposure of the limits of elegiac fides and his interaction with non-elegiac fides as part of the language of Roman social relations. These tensions are further exposed through his use of women’s speech, which depicts women as critical of both the elegiac scenario and of mainstream Roman values. Propertius uses the common elegiac trope seruitium amoris to consider issues of freedom, speech, and patronage both within and without the elegiac world and differs from the other Latin love poets in his presentation of his puella as possessing a measure of mastery. He also uses the equally common trope militia amoris to portray the elegiac world as morally superior to that of traditional militia, including epic poetry and contemporary conquest and empire-building. The existence of similar themes and critiques in the non-Cynthia poems, especially those that ostensibly praise Augustus, suggests the importance of further investigation into the connection between Propertius’ construction of masculinity and the social, cultural, and political change of the Augustan era.

Keywords: Latin Poetry
Propertius
masculinity
Augustan literature
Advisor: Keith, Alison
Improving our Understanding of Bioaccumulation in Humans, Fish and Surrogate Lipid Systems

The accumulation of polychlorinated biphenyls (PCBs) into humans was described using CoZMoMAN, a mechanistic multimedia fate and transport model coupled to a human food chain model. Model results demonstrated that concentration-age relationships for population cross-sections and individuals over time are not equivalent and that, under steady-state conditions, the lipid-normalized concentration of PCBs in an individual does not monotonically increase with age. By considering the decades-long emission history of PCBs in the model simulations, it was shown that an individual’s concentration mostly depends upon when she/he was born relative to the peak in emissions. Similarly, the two most influential factors controlling the shape of cross-sectional concentration-age trends obtained in human biomonitoring studies are the time lapse between the peak in emissions and sample collection and chemical elimination half-life. As a result, it should be possible to deduce information on these two factors from the shape of cross-sectional concentration-age trend. Reproductive behaviours (parity, age at birth, breastfeeding) were shown to potentially have a significant impact on exposure (and can contribute substantially to the observed variability in biomonitoring studies) though the mother’s reproductive history has a greater influence on the prenatal and postnatal exposures of her children than it does on her own cumulative lifetime exposure. A case study of the influence of dietary transitions in a hypothetical Arctic community demonstrated that dietary transitions are an important factor underlying the variability in PCB body burdens within and between subpopulations in addition to partially explaining the observed temporal trends. Comparison of PCB partitioning to various lipid materials suggested that 1) triolein is a good surrogate for human storage lipids; 2) liposomes are not an appropriate surrogate for human storage tissues; and 3) that partitioning into human MCF-7 cells is dominated by the storage lipids rather than by membrane lipids. Finally, a new bioenergetically-balanced bioaccumulation (3B) fish model is presented. Comparison of results from the 3B model with that of existing models revealed that feeding and growth rates used by previous fish bioaccumulation models were not bioenergetically consistent. Differences in biomagnification factors with fish size and temperature as a result of differing energetic requirements demonstrated the importance of the assumptions regarding growth rate and feeding rate.

Keywords: Environmental Chemistry
Bioaccumulation
Polychlorinated Biphenyls
Advisor: Wania, Frank
Demystifying the Commodification of Social Relations in the Ontario Child Protecton System: A Marxist Approach to Textual Analysis

Demystifying the Commodification of Social Relations in the Ontario Child Protection System: A Marxist Approach to Textual Analysis Susan Elizabeth Preston Doctor of Philosophy Faculty of Social Work University of Toronto 2013 In the space of quiet and disquiet, another read is possible. Abstract Capitalism invades all aspects of society, including the welfare state. Capitalist notions of the market appear to be encroaching into social services, wherein we see the “businessology” of social work; however, little empirical attention has been given to how capitalism appears to be replicated within social services. This research aims to make the invisible visible in order to agitate for radical change in the organization and practice of social service provision. In this inquiry, focusing on the child protection system in Ontario I examine some of the documentary actualities of the ruling apparatus of regulated parenthood and childhood by exploring the textualities of the state. Specifically, through the critical lens of Marxism and feminism, and drawing on my own experience of a classed and gendered world, I critically deconstruct the regulatory texts closest to the state, the legislation of the Child and Family Services and the regulations that expand the legislative intent. I also explore the procedural document of the Ontario Risk Assessment Model as an enacted text that operationalizes the legislation and regulation. By reading and re-reading these texts, at the surface but also above and below the surface, positioning the documents in context and recalling my social work practice, I seek answers to questions of how texts replicate capital, and commodify social relations through the ruling apparatus of the state. This work queries how the text itself in its active use of language has implications for social work, in practice, in research and in education.

Keywords: Marxism
child protection
textual analysis
Advisor: Chambon, Adrienne S.