VictorJuiz/thesis huggingface dataset:
Heterogeneous Photochemistry of Atmospheric Dusts and Organic Films

Little is currently known regarding the nature and consequences of interactions between photoactive surfaces, including mineral dust and ‘urban film’, and gas-phase pollutants in urban environments. In order to address this knowledge gap, this thesis explores the photochemical reactivity of these environmental surfaces in controlled laboratory settings. The photoenhanced ozonation of pyrene, a toxic product of incomplete combustion, proceeds at different rates and via different mechanisms at three model ‘urban film’ surfaces. These results are important because they suggest that the reactivity of a molecule on simplified surfaces may not accurately reflect its reactivity in the real environment. The photooxidation of isopropanol at the surface of TiO2, here used as a proxy for the photoactive component of mineral dust, yields gas-phase acetone. This chemistry is amplified by nitrate, a major surficial component of atmospherically processed dust. These results suggest that dust has the potential to convert non-absorbing species to photochemically active species, and thereby serve as a source of reactive organic radicals for further gas- or surface-phase chemistry. Oxalic acid, the most atmospherically abundant dicarboxylic acid, is efficiently oxidized to gas-phase CO2 at the surface of Mauritanian sand and Icelandic volcanic ash. These experiments indicate that the lifetime of oxalic acid may be limited in arid regions by Fe and Ti-catalyzed aerosol-phase photochemistry. Fluorotelomer alcohols (FTOHs), a class of industrial chemicals used in the production of surface coatings, undergo photooxidation at the surface of sand and ash to yield toxic and persistent perfluorinated carboxylic acids (PFCAs). These results provide the first evidence that the metal-catalyzed heterogeneous oxidation of FTOHs may act as a local source of aerosol-phase PFCAs. Illumination of Nigerien sand in the presence of gas-phase SO2 leads to the formation of surface-sorbed sulfate. This chemistry proceeds more efficiently on fine sand than on coarse sand. In chamber experiments, the illumination of SO2 in the presence of realistically produced dust aerosol results in new particle formation. Together, these results suggest that SO2 photochemistry at the dust surface has the potential to change not only dust hygroscopicity but also the net scattering potential of dust-containing air masses.

Keywords: heterogeneous
photochemistry
mineral dust
urban pollutants
Advisor: Donaldson, D. J.
Dark Matter

A single-movement work for full orchestra, Dark Matter presents its thematic material in a traditional manner, drawing especially on the conventions of sonata form. Moments of this thematic presentation, however, are either interrupted or extended using orchestrational techniques and thickening of harmonies inspired by “spectral” music. The Introduction of the piece is comprised mainly of these interruptions and extensions, with two different harmonic structures competing for dominance. The first structure is based on the natural harmonic overtone series, with each partial rounded to the nearest quarter-tone, and first appears in m. 3. The second structure is based on an inversion of the intervals that make up the partials of the natural harmonic series (also rounded to the neared quarter-tone), and first appears in mm. 8-9. The first half of the piece is dominated by the inverted version of the series. The first theme (m. 41) unfolds in a traditional manner, with the inverted harmonic structure integrated into extensions, interruptions, and even the bassline (m. 54). The second theme (m. 84), at a slower tempo, also serves as a transition to the climax of the piece (m. 106). This eventually leads to the breaking-through and return of the natural harmonic structure (m. 122, beat 3), and an extended period of exploration of this harmonic structure (mm. 122-172) – until the recapitulation (m. 173). The recapitulation features more appearances of the natural harmonic structure, most notably in the bassline as it begins. The inverted harmonic structure does return and push to another climax. This climax, however, is ultimately overtaken by the fundamental of the natural harmonic structure’s “break-through” from m. 122: “C” natural. It is this note that ends the piece, in unison.

Advisor: Kulesha, Gary
Secondary School Staffrooms as Perceived, Conceived, and Lived Spaces: An Investigation into their Importance, Decline, and Sublation

Secondary school staffrooms serve a genuine need for teachers not easily replaced by subject department workrooms, yet staffroom use in many schools has declined. As a result, some staffrooms are being turned into classrooms or even abolished altogether from secondary school designs. This dissertation investigates the causes and effects of the decline of secondary school staffroom use in a large Canadian school board. Henri Lefebvre’s spatial triad is applied to situate the investigation into spaces that are perceived, conceived, and lived. Staffrooms are analyzed as perceived spaces in the context of the production and reproduction of teachers’ labour, and the sub-communities of teaching found in workrooms. Staffrooms are viewed as conceived spaces by investigating their physical design and placement, as well as the role of secondary-level administrators in supporting or repurposing staffroom space. Staffrooms are understood as lived spaces by exploring how time, history, metaphor, and habit – especially habits formed in the early years of teaching – influence meaning for the users. Quantitative data drawn from a 23-question survey (256 responses) confirmed that although staffroom use had declined for the majority of respondents, secondary school staffrooms were still overwhelmingly considered to be necessary components of secondary schools even among non-users. The data analysis revealed that this decline was influenced by factors such as the isolated location of a staffroom, long distances from workrooms and classrooms to staffrooms, increased workloads, and habit. The findings of are supported by qualitative data in the form of 717 optional comments provided by survey participants, field notes from observing two secondary staffrooms: one inactive and the other frequently used, and through 26 semi-structured interviews held in five different staffrooms. It is my contention that staffrooms remain important to secondary school teachers as potential places for increasing perceptions of staff collegiality, providing opportunities for informal professional learning, developing cross-curricular connections, and managing teacher health and retention. The conclusion suggests how secondary school staffrooms might be reconfigured to better suit the needs of those who wish to use them.

Keywords: staffrooms
Henri Lefebvre
teachers' labour
department workrooms
spatial theory
secondary schools
Advisor: Sawchuk, Peter
Separable Spatio-spectral Patterns in EEG signals During Motor-imagery Tasks

Brain-Computer Interface (BCI) systems aim to provide a non-muscular channel for the brain to control external devices using electrical activities of the brain. These BCI systems can be used in various applications, such as controlling a wheelchair, neuroprosthesis, or speech synthesizer for disabled individuals, navigation in virtual environment, and assisting healthy individuals in performing highly demanding tasks. Motor-imagery BCI systems in particular are based on decoding imagination of motor tasks, e.g., to control the movement of a wheelchair or a mouse curser on the computer screen and move it to the right or left directions by imagining right/left hand movement. During the past decade, there has been a growing interest in utilization of electroencephalogram (EEG) signals for non-invasive motor-imagery BCI systems, due to their low cost, ease of use, and widespread availability. During motor-imagery tasks, multichannel EEG signals exhibit task-specific features in both spatial domain and spectral (or frequency) domain. This thesis studies the statistical characteristics of the multichannel EEG signals in these two domains and proposes a new approach for spatio-spectral feature extraction in motor-imagery BCI systems. This approach is based on the fact that due to the multichannel structure of the EEG data, its spatio-spectral features have a matrix-variate structure. This structure, which has been overlooked in the literate, can be exploited to design more efficient feature extraction methods for motor-imagery BCIs. Towards this end, this research work adopts a matrix-variate Gaussian model for the spatio-spectral features, which assumes a separable Kronecker product structure for the covariance of these features. This separable structure, together with the general properties of the Gaussian model, enables us to design new feature extraction schemes which can operate on the data in its inherent matrix-variate structure to reduce the computational cost of the BCI system while improving its performance. Throughout this thesis, the proposed matrix-variate model and its implications will be studied in various different feature extraction scenarios.

Keywords: Signal Processing
Pattern Recognition
Brain-Computer Interface
Feature Extraction
electroencephalogram
Advisor: Plataniotis, Konstantinos
The Effects of ROS and DNA Repair on Methylmercury-initiated Neurodevelopmental Deficits

Methylmercury (MeHg) is an environmental toxin to which we are exposed through the consumption of seafood. Reactive oxygen species (ROS) have been implicated in the mechanism of toxicity, and in vitro studies in our laboratory have implicated DNA oxidation, particularly the DNA repair enzyme oxoguanine glycosylase 1 (OGG1). My studies determined the effects of in utero exposure to MeHg on fetal brain DNA oxidation and postnatal neurodevelopmental deficits, and the role of ROS-mediated oxidative DNA damage using the free radical spin trap, α-phenyl-N-tert-butylnitrone (PBN), and DNA repair-deficient ogg1 knockout mice. While neither MeHg nor PBN altered DNA oxidation in fetal brain, MeHg caused cognitive deficits in passive avoidance and novel object recognition, the latter of which was blocked by PBN pretreatment, suggesting ROS involvement. Preliminary longevity studies following one litter from each treatment group to 16 months suggest that in utero MeHg treatment may shorten lifespan. Endogenous DNA oxidation was increased in the brains of ogg1 knockout fetuses compared to wild-type littermates, although this was not enhanced by MeHg. However, OGG1-deficient animals exhibited cognitive deficits in passive avoidance after MeHg treatment, suggesting a role for DNA damage. Furthermore, ogg1 knockout female mice exhibited a passive avoidance deficit compared to wild-type females regardless of treatment, corroborating a role for oxidative DNA damage in neurodevelopmental deficits. MeHg increased apoptosis in the hippocampal region of fetal brain, and may cause DNA double-strand breaks (DSBs), evidenced by enhanced phosphorylation of histone 2AX (γH2AX). Ogg1 knockout progeny exhibited increased cellular proliferation or migration in the developing hippocampal region, which was blocked by MeHg. My results provide the first evidence that: (1) MeHg may decrease lifespan; (2) PBN protects against some postnatal neurodevelopmental deficits caused by in utero exposure to MeHg; and (3) DNA repair-deficient progeny are more susceptible to postnatal cognitive deficits caused by in utero MeHg exposure, suggesting that ROS-mediated DNA oxidation plays a role in MeHg-initiated neurodevelopmental deficits.

Keywords: Methylmercury
DNA Repair
Neurodevelopment
Reactive Oxygen Species
Advisor: Wells, Peter G.
McPherson, J. Peter
The Relationship between Exposure to Pornography, Victimization History, Attachment to Parents, and the Sexual Offence Characteristics of Adolescents who Sexually Offend

This study was focused on exploring the relationship between victimization history, attachment to parents, pornography exposure/use, and characteristics of the sexual offences committed by male adolescents. It was hypothesized that, the poorer the attachment to parents, the greater number of abuses experienced, and the more exposure to pornography, the more likely an adolescent would be to have had more victims, have offended against more age groups, have both male and female victims, have committed penetration in his sexual offences, and have been forceful or violent in his sexual offences. The study involved secondary analysis of a large data set that was based on prior administration of an extensive survey which also included a number of psychological measures and questionnaires. A total of 308 male participants ranging in age from 13 to 20 at the time of completing the survey were included in this study. Participants were 12-17 years of age at the time of their sexual offending. A series of regressions were used to examine if attachment to parents, history of abuse/neglect, and pornography use could predict the number of victims, age group of victims, gender of victims, sexual intrusiveness, and level of force in the sexual offences that had been committed by the participants. Predictor variables that emerged as important in this study were the duration of the sexual offending, having experienced three or more types of abuse, and exposure to live sex. In general, it was suggested that treatment efforts should focus on intervening promptly and reducing the duration of an adolescent’s sexual offending and that intervention for all types of abuse be prioritized. Additionally, it was recommended that future research seek to identify characteristics that might predispose certain victimized individuals to develop sexual offending behaviours in the future. In general, it was noted that further explorations are needed regarding applicable theoretical approaches, as well as the various factors, and interactions among factors, that contribute to the characteristics of sexual offences committed by male adolescents.

Keywords: pornography
sexual offenders
adolescent
Advisor: Mishna, Faye
Development of Multi‐purpose Lipid Coated PNIPAM Microgels and Techniques for Characterizing Lateral Diffusion in Bilayers

The pursuit of a greater understanding of the biological membrane has led to the development of a number of mimetics and probing techniques. This thesis contributes to both of these efforts. Towards the development of mimetics, poly(N-isopropylacrylamide) (pNIPAM) microgels were explored as membrane supports. PNIPAM microgels are “smart” materials that experience a volume phase transition (VPT) at ~32°C, where they undergo a severe loss in volume. The core-shell microgels were synthesized with a low crosslinked pNIPAM core covered by a highly crosslinked pNIPAM shell that was functionalized with exploitable carboxylates. It was shown that a lipid bilayer could be coated on these microgels using either liposomes or bicelles. Specifically, lipid bilayer enclosed microgels made with liposomes (“Lipogels”) were created by using hydrophobically modified microgels, which possessed the ability to sequester liposomes that could ultimately be fused into a continuous bilayer. It was also found that above the VPT temperature, surface decoupled lipid protrude into highly curved structures. Hence, the VPT property could be used to control the curvature of the Lipogel bilayer. These particles could be useful platforms for conducting biophysical membrane studies as well as drug delivery vehicles. Bicelles were also explored as lipid sources for microgel coating, resulting in the creation of “Bicellogels”. Electrostatic attraction between cationic bicelles and unmodified anionic core-shell pNIPAM microgels resulted in the coating of the latter. Astonishingly, the resulting bilayer was made up of only the long chain bicellar lipid. Due to the simplicity of this method, it could be extended to easily coat all types of soft material. The last development on the pNIPAM front involved the coupling of intact liposomes to microgels to create “VESCOgels”. These complexes offer two distinct cargo holds through which temporally distinct release can be achieved. Hence, they could be very useful for applications in tandem release. Lastly, the 31P CODEX NMR technique was adapted to study the lateral diffusion of phospholipids in large liposomes. This technique allows for the measurement of lateral diffusion coefficients of multiple phospholipids simultaneously. This could prove useful for the study of such biologically relevant phenomena as domain formations and drug-lipid interactions.

Keywords: pNIPAM
lateral diffusion
Advisor: Macdonald, Peter
Resort Urbanism: Understanding the Power, Planning and Politics of Urban Development in Bávaro-Punta Cana, Dominican Republic

In many developing countries, particularly Small Island Developing States (SIDS), coastal tourism impacts local economies and societies in significant ways, and plays an important role in transforming the environment. Rather than simply interpreting the changes that occur around coastal tourist enclaves as impacts, I argue that it is important to recognize the urban nature of spaces proliferating around these enclaves and to understand the role of the actors of coastal tourism in the production of these spaces. Utilizing a case study (Bávaro-Punta Cana, Dominican Republic), my research draws from over one year of fieldwork, including 97 semi-structured interviews with local residents, researchers, and various stakeholders. I examine the power relations between the private sector, local residents, and different levels and sectors of the State in the area’s urban development process. The context of Bávaro-Punta Cana is characterized by the following three issues. First, the newly established local government is generally impotent vis-á-vis other State actors and powerful private sector interests, and is unable to ensure the public good for its citizens. Second, many local residents live in conditions that are worse than traditional urban areas in the country. Third, the private sector has inserted itself as pivotal actor in the development and governance of the newly urbanizing area through practices of corporate social responsibility. Based on my analysis, I refer to the realities of Bávaro-Punta Cana as ‘resort urbanism.’ I utilize this term to illustrate the manifestations of tourism-related urbanization. Drawing from planning concepts, namely splintering urbanism, informality and citizenship, I analyze the physicality and spatiality of urbanization, the processes of urban development, and the rights of citizens and the relations between actors in the production of this new urban space. First, I argue that urban space in Bávaro-Punta Cana is produced as a form of ‘splintered urbanism.’ Second, this space is materially shaped by practices of informality or what is known locally as arrabalización. Last, the area lacks a local governance structure through which residents can adequately make claims to fulfill their basic needs, raising important questions regarding the rights and responsibilities of different actors in urban development.

Keywords: governance
urban
tourism
planning
Dominican Republic
poverty
Advisor: Daniere, Amrita
“All for the Family”: A Case Study on the Migration of Philippine Educated Nurses to Ontario through the Live-in Caregiver Program

Despite evidence that suggests that nurses migrate to Ontario through the Live-in Caregiver Program, no research has been conducted on this group of nurses in Ontario. This study addresses that gap utilizing the transnational feminist concept of “global care chains” in a single holistic case study design to explore the experience of nurses who migrate to Ontario through the Live-in Caregiver Program (2001-2011), and examine the diverse perspectives of stakeholders on issues of rights and obligations of these nurses. Fifteen live-in caregivers and nine policy stakeholders were interviewed, and an analysis undertaken of immigration and nursing policy documents. Findings indicate that familial discourses and perspectives on global social status shape these women’s decision to migrate from the Philippines to Canada, often via a second country (especially Saudi Arabia), as well as their subsequent Canadian experiences. Results are consistent with Rhacel Parrenas’ idea of ‘contradictory class mobility’ that describes the phenomenon of decrease in social status coupled with an increase in financial status among immigrant care workers. As professional women undertaking unskilled work, the nurses’ contradictory class status was reinforced by the emotional labour and domestic work they were required to perform. Furthermore, as temporary workers on a path to permanent residency, their professional integration as nurses was complicated by Canada’s immigration policy and the paradox between the government’s stated short-term goal (to address labour force shortage of live-in caregivers) versus its long-term goal (to ensure the integration of permanent residents). Within this policy paradox immigration policy makers emphasized the short-term obligation of fulfilling labour needs, while live-in caregivers and advocacy groups emphasized the long-term obligations of the Canadian government related to gaining permanent residence status. The lack of congruence between the Live-in Caregiver Program policy and nursing policy concerning internationally educated nurses, as well as prioritization of their familial obligations complicated the process of professional integration for this group of women. Recommendations arising from the study concern the need to bridge these policy gaps and address the shortcomings of the Live-in Caregiver Program to leverage the integration of this group of internationally educated nurses in Canada.

Keywords: Nurse Migration
Health Human Resources
Philippine
Internationally Educated Nurses
Live-in Caregivers
Immigration
Domestic Workers
Ontario
Immigrant Nurses
Home caregivers
Nanny
Migrant Workers
Advisor: Nelson, Sioban