VictorJuiz/thesis huggingface dataset:
If a Tree Falls in the Urban Forest: Current and Future Pest Vulnerability in Toronto's Urban Forest
Keywords: pest vulnerability
planting trends
species composition
Toronto
tree pests
urban forests

Urban forests represent a valuable resource for cities. Accounting for species diversity and vulnerability to pests when managing an urban forest can help enhance services delivered and minimize management expenses. In this research, tree genera currently prevalent and commonly planted in Toronto were analyzed using a pest vulnerability matrix to explore how the city's urban forest's pest vulnerability may be changing. Current tree species composition was derived from inventory data, while the planting trends of a variety of local actors were determined through surveys and interviews. Results suggest some genera show clumped distributions and occasionally surpass recommended diversity thresholds in a given district or citywide. On-going planting behaviours in Toronto are replicating some current diversity issues while also increasing less common species. As a result, Toronto's vulnerability to tree pests and diseases will likely decrease, but certain serious issues will continue.
The Thermal Design and Analysis of the CanX-4/-5 and NEMO-AM Nanosatellites
Keywords: nanosatellites
passive thermal control
small satellites
thermal control

The main appeal of small satellites is that they are capable of fulfilling many of the same tasks as larger satellites, with lower development and launch costs. However, their smaller size can impose limitations on many of their systems, including their thermal control systems, which are often required to be passive and simple. This work summarizes the design and analysis of the thermal control systems for two small satellite missions, CanX-4/-5 and NEMO-AM. The development of a finite-difference thermal model using a commercial software package is described, followed by an overview of the analysis performed and the thermal control strategies employed in the satellites. The final analysis predictions show that the satellite temperatures for both missions were maintained within their required limits.
Sunlit Leaf Photosynthesis Rate Correlates Best with Chlorophyll Fluorescence of Terrestrial Ecosystems
Keywords: BEPS
chlorophyll fluorescence
ecological modelling
GPP

This thesis attempts to link carbon assimilation micro-processes to macro-scale chlorophyll fluorescence measurements. The Boreal Ecosystem Productivity Simulator (BEPS), a process-based model, is adopted to simulate the hourly global-scale gross primary productivity (GPP) in 2010. The total GPP is stratified into sunlit and shaded GPP using a two-leaf scaling approach. Concurrently, the usefulness of solar-induced chlorophyll fluorescence as a proxy of GPP is also assessed. Relatively precise global monitoring of fluorescence is made possible with a new retrieval method applied to GOME-2 observations. Linear correlation analysis is used to examine the monthly spatio-temporal patterns between GPP and fluorescence. The hypothesis that sunlit GPP is better correlated with fluorescence than total or shaded GPP has been successfully tested with GOME-2 data and BEPS results. Since shaded GPP is about 40% of the total GPP globally, this result points to a limitation of using fluorescence as a proxy of the total GPP.
Brain Signal Complexity and Creative Ability in Bilingual and Monolingual Children
Keywords: Bilingualism
Creativity
Development
Executive function
Neural Complexity

Childhood bilingualism has long been associated with enhanced creative performance. The neural mechanisms underlying this phenomenon, however, have yet to be characterized. Research suggests bilingualism modifies neural networks for executive control. Such changes, which can be assessed with estimation of neural signal complexity, are thought to increase information processing capacity. We thus compared electroencephalographic signal complexity during a Go/No-Go task in bilingual and monolingual children aged 4 to 6, and correlated these complexity estimates with creative ability. Differences in EEG complexity were found in left centro-parietal and right frontal scalp regions. Complexity, however, did not correlate with children's creative performance scores. Although our findings failed to explain the neural link between bilingualism and enhanced creativity, we did find evidence to support the notion that bilingualism during early childhood is associated with functional brain changes in areas related to executive functioning.
Timing Skew Calibration for Time Interleaved Analog to Digital Converters
Keywords: ADC
Calibration
SAR
Time-Interleaved
Timing Skew

This thesis presents a novel background timing skew calibration method used to improve the dynamic performance of time-interleaved analog-to-digital converters. A prototype 10GS/s 8bit 80-way time-interleaved SAR ADC was designed and fabricated in 65nm CMOS to illustrate this concept. The performance of a subset 5GS/s ADC is reported due to inadequate delay buffer range. After calibration, the 5GS/s ADC achieves an SNDR of 33.3dB at Nyquist and consumes 138.6mW from a 1V supply, yielding an FOM of 738fJ/conv-step.
Construction of FcHyd5p Variants to Assess the Potential of These Class II Hydrophobins as Molecular Tools for Surface Modification
Keywords: Cell Adhesion
Hydrophobin
Hydrophobin Production
Hydrophobin Purification
Surface Modification

Hydrophobins represent an attractive surface modification technology that can be paired with a variety of fusion partners to increase their versatility. Surface modification is a technique widely used to influence the adhesion of molecules to surfaces. The aim of this project is to assess the potential of the class II HFB FcHyd5p from Fusarium culmorum as a surface modification technique. FcHyd5p variants bearing RGD with two different linker sequences were engineered. Proteins were expressed in Pichia pastoris and purified using fast protein liquid chromatography (FPLC) and affinity chromatography. Bis-Tris-SDS-PAGE confirmed that native and fusion proteins were successfully produced and purified, with yields of the fusion constructs exceeding that of the native. Water contact angle demonstrated that RGD-FcHyd5p constructs could convert surface wettability of siliconized glass. Quartz crystal microbalance with dissipation (QCM-D) quantified HFB adsorption and assessed the effect of the presentation of RGD through different linkers on cell adhesion.
Investigations of the Functional Expression of SLC6A14 in Non-CF and CF Airway Epithelial Cells
Keywords: amino acid transport
cystic fibrosis
epithelial physiology
SLC6A14

Recent studies have found single nucleotide polymorphisms significantly associated with more severe cystic fibrosis (CF) in the promoter region of the SLC6A14 gene, encoding a NaCl-dependent neutral and cationic amino acid transporter highly expressed in the lung. In a CF human bronchial epithelial cell line (CFBE41o-) transfected with wild-type- (CFBEwt) or dF505-CFTR (CFBEdf), 3H-arginine uptake followed Michaelis-Menten kinetics (CFBEwt Kt=95.01±14.05, CFBEdf Kt=72.8±16.14). Competitive inhibition experiments demonstrated function attributable to SLC6A14 and cationic amino acid transporter system y+ in both cells. Intracellular and transepithelial transport of 3H-arginine in non-CF and CF primary human airway cells was significantly reduced (~50%) in 0 Na+ or presence of a SLC6A14 blocker, alpha-methyl-DL-tryptophan (alpha-MT) apically, indicative of SLC6A14. There was no difference in SLC6A14 function between CF and non-CF cells, or CFBEwt and CFBEdf cells. These protocols allow isolation of SLC6A14 function in airway cells by competitive inhibition, Na+ dependence, and alpha -MT sensitivity.
Household Indebtedness and Socio-Spatial Polarization among Immigrant and Visible Minority Neighbourhoods in Canada's Global Cities
Keywords: Debt
Housing
Immigration
Neighbourhoods
Political Economy
Race

Two key attributes of contemporary global capitalism are on the one hand, financialization and rising household indebtedness, and on the other, high levels of mobility and migration between nations, particularly into the `global' cities. Studies on household debt as it relates to race and immigrant status are scarce outside of the US. This thesis investigates levels and types of household indebtedness at the neighbourhood scale among immigrant communities and areas containing more racialized people, in the three largest Canadian cities - Toronto, Montreal, and Vancouver (TMV). In particular, it seeks to understand whether racialized and immigrant neighbourhoods experience higher and more onerous kinds of debt (such as unsecured forms of consumer debt) than other neighbourhoods, and the contours of any correlations between them. Descriptive statistics and regression models demonstrate that neighbourhoods housing immigrant groups, and certain visible minority groups, relate to higher levels of unsecured consumer debts in TMV.
Investigating the Function of GTF2I and its Contribution to the Williams-Beuren Syndrome Neurological Profile
Keywords: 7q11.23
GTF2I
iPSC
neurogenesis
WBS
Williams

Williams-Beuren Syndrome (WBS) is a genetic neurodevelopmental disorder caused by the deletion of 25 protein-coding genes at chromosome 7q11.23. It is associated with a highly penetrant constellation of phenotypes, including aortic stenoses, characteristic facial features, and unique cognitive and behaviour profiles. I hypothesize that the gene GTF2I, a putative transcription factor, plays a role in signaling pathways that affect neuronal function and contribute to the WBS neurological profile. Genome-wide expression analysis of WBS patient-derived induced pluripotent stem cells and cortical neurons isolated from mice with a duplication or deletion of Gtf2i identified moderate changes in the expression of a few genes. Additionally, affinity purification and tandem mass spectrometry of GFP-tagged GTF2I validated a previously identified interaction with ZMYM3, a candidate for X-linked intellectual disability. Future studies to determine the consequence of this interaction in the brain will assist in characterizing GTF2I function in neurons and its contribution to WBS phenotypes.
Development of Self-assembled Amphiphilic Oligo-urethanes as Cardiovascular Drug Delivery Platforms
Keywords: Drug delivery
Restenosis
Oligo-urethanes

Current drug-coated balloon (DCB) technologies, used to prevent percutaneous coronary intervention-related restenosis via antiproliferative agent delivery to arterial lesions, are associated with systemic drug loss during catheter tracking and inefficient drug delivery to target tissues. This thesis aimed to study and synthesize novel amphilphilic oligo-urethanes (AOUs) as DCB drug carriers comprised of polyol, lysine diisocyanate and perfluoro-alcohol (PFA) segments to enhance drug release, binding and shielding against premature release respectively. AOU syntheses employing di-hydroxyl polyols were found to be susceptible to pre-polymer intramolecular cyclization, which prevented PFA conjugation. Such undesired cyclization reactions were circumvented in this thesis via the use of a mono-functional polyol to yield AOU analogues that were water soluble (≥430 mg/mL solubility) and relatively phase mixed. Fluorocarbon groups migrated to the surfaces of analogue films, yielding water contact angle values ≤51o. Preliminary analogue-cell compatibility studies and capillary electrophoresis-mediated drug-AOU dissociation assessments were conducted and are reported.
Assessing Pubertal Timing and Dynamics in a Large Longitudinal Sample of Adolescent Males
Keywords: Neuroscience
Testosterone
Male
Adolescence
Pubertal Timing
ALSPAC
Magnetic Resonance Imaging
White Matter

Pubertal timing and dynamics play an important role in physical and psychological development. This thesis describes three height-based indices that can be used to assess pubertal timing, and a measure of average exposure to testosterone derived from testosterone trajectories to assess pubertal dynamics. These parameters are derived in a sample of 500 male adolescents from the Avon Longitudinal Study of Parents and Children (ALSPAC). The indices of pubertal timing are shown to correlate with one another in ALSPAC. In a separate cross-sectional study, we show the association between one index and both testosterone levels and self-reported pubertal stage. The measure of average exposure to testosterone characterizes the timing and the magnitude of the rise in participants&rsquo; testosterone levels during adolescence. Future investigations may employ the methods outlined to account for timing and dynamics of puberty in relation to adolescent development.
Regulation of Kisspeptin-expressing Neurons and Stimulatory Mode of Action of Kisspeptin in Immortalized Hypothalamic Cell Models
Keywords: Kisspeptin
Hypothalamus
Neuron
GnRH
Estradiol
GnIH
Neuropeptide

Fertility is a highly regulated process dependent on the orchestration of hypothalamic neuropeptides and peripheral hormones, which converge on GnRH neurons in the HPG axis. Kisspeptin and its receptor, Gpr54 have emerged as fundamental gatekeepers of reproduction, acting upstream of GnRH neurons. Kiss neurons have been found to express estrogen receptors, Gpr54 and the GnIH receptor, Gpr147. We have generated immortalized, murine hypothalamic cell lines to investigate mechanisms of gene transcription in kisspeptin-expressing neuronal cell models. We show using qRT-PCR and western blot analyses that kisspeptin-expressing neuronal models are targets for gonadal steroids and hypothalamic neuropeptides. Further, using a novel GnRH-secreting cell line, we report that GnRH neurons expressing Gpr54 and Gpr47 are stimulated by kisspeptin, although suppressed by a kisspeptin/GnIH cotreatnent. Overall, these studies expand our knowledge of the regulation of Kiss neurons by estradiol, kisspeptin and GnIH, improving our understanding of kisspeptin as a modulator of GnRH neurons.
Microfluidic Selection of Spermatozoa Based on Total Progressive Motility and Wall-swimming Behaviour
Keywords: microfluidics
sperm selection
wall-swimming
assisted reproduction
ART
methyl cellulose
hyaluronic acid
DNA integrity

Worldwide, 9% of couples encounter fertility problems, seeking medical assistance from assisted reproductive technologies (ARTs). Unfortunately current spermatozoa selection techniques required for ARTs have evolved little in 40 years, and depend heavily on the clinician&rsquo;s ability to manipulate and select spermatozoa for fertilization. Microfluidic devices have emerged as a potential solution to selecting viable spermatozoa for ARTs. A challenge to current microfluidic approaches is that they require extensive equipment in order to achieve the flow needed to separate the spermatozoa. In this thesis a microfluidic device was used to compare high viscosity buffers to create an environment that more closely resembles the female reproductive tract. Microfluidics was also employed to select spermatozoa using wall-swimming behaviour. The findings showed that selecting left and right wall-swimming spermatozoa will yield better DNA integrity than the traditional Percoll centrifugation technique. Both bovine and human spermatozoa were utilized throughout this thesis.
Justice and Starvation in Cambodia: International Criminal Law and the Khmer Rouge Famine
Keywords: International criminal law
famine
starvation
international criminal justice
crimes against humanity
Khmer Rouge

Recently, an interdisciplinary discourse has emerged concerning the suitability of international criminal law as a legal response to severe famine. Despite this discourse, the topic of famine has received scant attention within actual international criminal law practice. This thesis scrutinizes this prosecutorial gap by considering whether former Khmer Rouge leaders could likely be successfully prosecuted for international crimes predicated on the catastrophic famine that occurred while the Khmer Rouge held power in Cambodia from 1975-1979. To do so, a detailed history of the Khmer Rouge period famine is developed and subsequently analyzed according to current formulations of international crimes. This analysis concludes that former Khmer Rouge leaders could likely be prosecuted for crimes against humanity, specifically those of extermination, persecution and other inhumane acts, predicated on their roles in enforcing famine conditions while in power.
To Do It or Not to Do It? The Role of Communal Motivation in Sexual Decision Making
Keywords: Sexuality
Communal Motivation

In long-term romantic relationships, sexual satisfaction and sexual frequency are key to maintaining relationship satisfaction and stability. However, very little research has investigated how couples actually make decisions about whether or not to engage in sex on a day-to-day basis. Across two studies, a hypothetical scenario study and a daily experience study, we found that sexual communal strength ¬¬¬̶ the degree to which one is motivated to meet their partner’s sexual needs ¬¬¬̶ predicts decreased motivation to avoid the costs to the self of engaging in sex, as well as increased motivation to accrue benefits to the partner of engaging in sex. In turn, this predicts greater willingness to engage in sex, as well as greater sexual and relationship satisfaction for both partners. Greater sexual communal strength influences the sexual decision making process, with positive consequences for both partners in the domain of sexuality, and in relationships more generally.
The Role of Septin in Ciliogenesis
Keywords: septin
primary cilium
ciliogenesis

Septins are an evolutionarily conserved family of proteins that have recently been implicated in the formation of primary cilia. Work in our lab has shown that SEPT9 binds and activates a specific guanine nucleotide exchange factor for Rho, SA-RhoGEF, to promote Rho activation. Interestingly, SA-RhoGEF is localized to the basal body, raising the possibility that SEPT9-SA-RhoGEF interaction may be important in ciliogenesis. We therefore depleted SEPT9 expression in hTERT-RPE1 cells, and noticed significant shortening of the cilia upon SEPT9 depletion. We were able to rescue this phenotype by targeting either a constitutively active truncation of SA-RhoGEF, or a full length SEPT9, to the basal bodies. Our study suggests that SA-RhoGEF activity is involved in the formation of the cilia, and SEPT9 is required to interact with SA-RhoGEF at the basal body in order to achieve adequate RhoA activation.
Improving the Mechanical Properties of Irradiation-sterilized Bone
Keywords: bone allograft
biomaterials

Bone allografts are used in orthopaedic reconstruction of defects resulting from trauma, bone cancer or infection. Gamma-irradiation sterilization is a safety measure; however it damages the tissue, specifically the organic component, and embrittles bone. This research investigated the effect of ribose pre-treatment on the mechanical properties of ribose-modified irradiated bone. The overall goal was to develop a method for improving toughness of irradiation-sterilized bone by modifying collagen with a ribose treatment prior to/during irradiation. Bulk mechanical properties and fracture properties were evaluated. Collagen characterization techniques were used to further understand the collagen alterations and suggest toughening mechanisms. We have shown it is possible to recover some of the mechanical properties of &gamma;-irradiated bone as well as collagen thermal stability and connectivity using our ribose pre-treatment. We propose that the recovery of collagen connectivity leads to functionally significant recovery of toughness, fracture toughness and strength.
Does Location Matter? How Neighbourhoods Influence Out-of-hospital Cardiac Arrest Outcomes
Keywords: Cardiac arrest
Cardiopulmonary resuscitation
geographic information system
emergency medicine
emergency medical services
public health

Out-of-hospital cardiac arrest (OHCA) is a life-threatening emergency. Research from other disciplines has suggested that location is a strong determinant of health outcomes. Therefore, the objective of this thesis was to determine the role of neighborhoods in OHCA. We hypothesized that neighbourhood factors are associated with: survival to hospital discharge, a return of spontaneous circulation (ROSC) at emergency department (ED) arrival, and provision of bystander cardiopulmonary resuscitation (CPR). This thesis demonstrates that for the most part neighbourhood inequalities were not associated with outcomes. This thesis confirmed that, while the Utstein variables account for a large portion of patients who survive, they poorly account for patients who had a ROSC at ED arrival or received bystander CPR. Inclusion of neighbourhood factors to the Utstein variables significantly improved discrimination for survival and a ROSC at ED arrival, but not bystander CPR. Future research should determine what additional factors could predict outcomes.
The African Brain Drain and the Social Impact of Skilled Migration
Keywords: Africa
brain drain
social impact
skilled migration
slavery
colonialism
anti-colonial thought
historical context
professionals
remittances
pull-pull theory
family
education
overqualification
discrimination
identity
immigrants
mental health
corruption
poverty
political instability
unemployment
return
government
investments
debates
migrants
experience
economic impact
diaspora

The rapid rate at which educated Africans are migrating to the West has garnered much attention among scholars and has been termed ‘brain drain’. This thesis presents two arguments. First, understandings of brain drain from the African continent must be rooted in a historical context. The problems that the continent faces today have been shaped by key historical events including slavery and colonialism. Secondly, the impact of brain drain extends beyond the cost-benefit analysis related to remittances and loss of investments to the countries involved. Brain drain has significant social impacts on African immigrants in the diaspora. As such, it is important to highlight some of the triumphs and challenges that characterize the migrant experience.
Photoperiod Dependent Plasticity of GABA-mediated Effects on Neuronal Activity in the Pond Snail Lymnaea stagnalis
Keywords: GABA
L. stagnalis
KCC2
NKCC1
Hypoxia

GABA is the primary inhibitory neurotransmitter in the mature mammalian CNS. Within the snail central ganglion, however, there are contradictory reports on the role of GABA, citing both inhibitory and excitatory effects. Previous work has suggested a seasonal shift in the polarity induced by GABA. My thesis work investigated whether changes in photoperiod were responsible for the seasonal shift in GABAergic polarity. Using intracellular sharp recordings from cluster F neurons within the pedal ganglia, I determined that the majority of snails exposed to either a 16h:8h or 8h:16h light:dark cycle exhibited significant hyperpolarizing inhibitory responses or depolarizing excitatory responses to GABA application, respectively. Additionally, using gramicidin-perforated patch recordings I found a shift in the reversal potential for GABA. I conclude that the seasonal shift in GABA-mediated effects results from a shift in intracellular [Cl¯] that is photoperiod dependent and is likely mediated through the relative efficacy of cation chloride co-transporters.