Trent University

This thesis develops an Long Short-Term Memory (LSTM) neural network model to assess the relationship between ambient air pollutant exposure and public health risks, accommodating both linear and nonlinear associations with distributed lags.The research makes three key contributions. First, Maximal Information Coefficient (MIC) methods identify the most relevant air pollutants and their associations with health outcomes. Second, an LSTM model extracts temporally dependent features from exposure series to estimate health impacts. Finally, the model's potential in air pollution epidemiology is explored using Local Interpretable Model-Agnostic Explanations (LIME) to interpret the exposure-health response relationship.

Author Keywords: air pollution epidemiology, Deep Learning, explainable AI, Long Short-Term Memory, Maximal Information Coefficient, public health assessmen

Understanding tissue turnover rate is crucial for isotopic analysis. Collagen, a main component of bone, is often studied in archaeology and paleontology, yet bone collagen turnover rates across various skeletal elements, remain underexplored. This study addresses this by assessing collagen turnover rates in multiple human skeletal elements using the bomb carbon dating method. Seven donors, aged 54 to 78, from the REST[ES] facility in Québec, were sampled. Turnover rates varied significantly among skeletal elements, ranked from slowest to fastest as follows: ulna, humerus, femur, rib, pelvis, and vertebra. It was shown that turnover rates are not consistent throughout life and are not averaged over a turnover period. For studies aiming to reconstruct temporal variation in life history, vertebrae and ulnae should be used due to their distinct turnover rates. This research provides the most comprehensive list of bone collagen turnover rates for various human skeletal elements.

Author Keywords: Bomb carbon dating, Bone collagen, Human physiology, Radiocarbon, Stable isotope analysis, Turnover rate

Mutations in the CLN7 (MFSD8) gene, causes CLN7 disease, a subtype of neuronal ceroid lipofuscinosis. MFSD8 is a lysosomal transmembrane protein that transports chloride across membranes. Experimentation regarding Dictyostelium discoideum revealed that mfsd8 deficiency altered lysosomal enzyme activity. During starvation, the aggregation of mfsd8¬¬- cells was delayed, and cells formed more mounds that were smaller in size, phenotypes that were attributed to reduced cell-substrate adhesion and altered lysosomal enzymatic activities. This study examines the possible transcriptomic and secretomic basis for these phenotypes. This work generated new datasets for examining the effect of mfsd8 loss on the transcriptome and secretome. The validity of these datasets was supported by use of western blotting and RT-PCR along with a set of assays probing relevant biological processes. Together these results elucidate the biological mechanisms behind the observed phenotypes and lay the foundation for future studies to further study the cellular role of MFSD8.

Author Keywords: Battens disease, CLN7, Dictyostelium discoideum, MFSD8, Secretome, Transcriptome

This thesis presents the excavation and analysis of Structure D-6 at the Maya city of Ka'kabish in what is now North-Central Belize. Structure D-6, together with Structure D-7, comprise the site's only known ballcourt. Performance theory is used in tandem with the existing literature about the Mesoamerican ballcourt's crucial function within the legitimization strategies of Maya elites to understand Ka'kabish's position in its political landscape. Comparisons are also made between Ka'kabish and Lamanai's markers of elite activity to judge the plausibility of various degrees of political integration between the two sites. This study is significant as North-Central Belize is traditionally overlooked by scholars of the ancient Maya in favor of the more extensively analyzed Central Petén and Yucatan Peninsula, leading to simplified, static constructions of the region's political history. The findings of this study suggest a more dynamic, complex past for these cities and this area than previously thought.

Author Keywords: Ballcourts, Belize, Classic Maya, Monumental Architecture, Performance Theory, Sociopolitical Organization

Darwinian fitness is determined by the outcome of allocations of energy and nutrients to plant growth, survival, and reproduction. Allocations to reproduction differ from allocations to growth and survival because the products of reproduction (pollen, ovules, and fruits) are dispersed away from the plant and so the resources used to produce them cannot be re-allocated. As a result, and because the total resource pool available to a plant is limited, allocations to reproduction can reduce future growth, reproduction, and/or survival, yielding fitness costs of reproduction. This study provides a novel approach to detecting the costs of reproduction through multiple reproductive currencies, including both biomass and nitrogen allocations and their temporal effects on current and future plant performance. My results demonstrate the environmental dependence of the costs of reproduction and show that under certain conditions, males can bear greater costs than females, contrary to the prevailing view.

Author Keywords: Cost of reproduction, dioecy, flower removal, life-history trade-offs, photosynthetic machinery, sexual dimorphism

Despite the extensive application of Baumrind's parenting style typology, some argue that it may not adequately capture the implicit warmth Chinese parents embrace. This study attempted to examine whether mind-mindedness could be a key indicator for helping children understand the benevolent intentions behind their mothers' authoritarian parenting practices. Specifically, this study investigated the variations in parenting styles, mind-mindedness, and children's behavior problems in Canada and China, the relationship among these variables, and the moderating effect of mind-mindedness on the relationship between authoritarian parenting and children's behavior problems. Participants were 83 Canadian and 136 Chinese mother-child dyads. Data on parenting styles, mind-mindedness, and problem behaviors were collected from maternal reports and lab observations. As expected, while Chinese mothers exhibited more authoritarian tendencies than Canadian mothers, their mind-mindedness buffer against the negative effect of maternal high-power strategies on children's behavior problems after controlling for maternal age and education. These results provide new perspectives on understanding Chinese parenting.

Author Keywords: culture, externalizing behaviors, internalizing behaviors, mind-mindedness, parenting styles, preschoolers

This study investigates associations between self-other differentiation (the ability to distinguish and coordinate the self and other perspective during social problem-solving) and specific ego functions (reality testing, judgement, sense of reality, object relations, and synthetic-integrative function) from a cognitive perspective in two groups of adolescents aged 12 to 18 years. One group was referred for mental health problems (clinic-referred, n = 129) and the other was a typically developing comparison group (control, n = 184). Clinic-referred adolescents scored significantly lower in both self-other differentiation and ego functions compared to nonclinic-referred adolescents, suggesting a potential relation with adolescent mental health. While self-other differentiation was generally associated with ego function, no moderating effect of clinic referral was observed. Findings suggest a link between self-other differentiation and different aspects of judgement (the ability to anticipate consequences, understand reactions, and learn from past mistakes).

Author Keywords: adolescence, ego function, interpersonal negotiation strategies, mental health problems, self-other differentiation, social problem solving

The TATA-binding protein (TBP) is a key regulator of eukaryotic transcription initiation. The TBP homolog from Giardia intestinalis (gTBP) is highly divergent among all TBPs; notably lacking three of the four phenylalanine residues to unwind double- stranded DNA. I show that gTBP preferentially binds to single-stranded DNA (ssDNA) in two modes based on sequence and protein concentration. The proposed A mode likely represents multimeric binding of gTBP to ssDNA with four or more consecutive guanine bases. The B mode involves monomeric binding utilizing the structural properties of the ssDNA. To demonstrate this, I developed a novel technique using base stacking energy potentials to approximate the per-nucleotide flexibility of ssDNA. I also attempted to create a polynomial regression model to predict binding; however, further work is required to improve accuracy. Overall, this thesis presents a new perspective on eukaryotic transcription regulation based on the discovery of unconventional binding between gTBP and ssDNA.

Author Keywords: computer modelling, DNA binding protein, DNA structure, DNA transcription, general transcription factor (GTF), parasite

Innovative strategies to manage copious waste streams by upcycling feedstocks to valorized products which are then used in environmental remediation applications is an attractive circular economy model. This thesis explores this approach using waste wood generated from the milling of Chlorocardium rodiei (greenheart), a tropical hardwood species abundant in Guyana. We evaluate the thermochemical conversion of this feedstock, using phosphoric acid as the activant, to super activated carbons with surface areas of more than 2200 m2/g. Owing to the presence of surface heteroatoms, these adsorbents are amenable to further surface modifications including base-treatment, O-functionalization and N-functionalization. Using a facile oxidation procedure and shrimp waste-based dopants, we increase oxygen and nitrogen content by 8-fold and 5-fold respectively. These increases are realized without catastrophic loss of surface area and porosity as generally occurs with many reported functionalization approaches. Functionalized materials demonstrated efficient removal of both metal ions and the chlorinated herbicides 2,4-dichlorophenoxy acetic acid and paraquat. Pristine and base-washed ACs removed more than 90% of iron, aluminum and manganese from natural pit-lake waters. O-functionalized adsorbents also showed excellent removal efficiencies for aluminum and lead but only removed moderate amounts of manganese. Nitrogen-enriched composites fabricated with the addition of commercial chitosan removed 67% 2,4-D and 89% paraquat from model solutions at environmentally relevant concentrations of 4 ppm and 40 ppm respectively. Their versatility is further demonstrated in their ability to remove both herbicides from binary mixtures albeit to different extents. Shrimp chitin-based composites were most effective at removing 2,4-D from model solutions with a maximum adsorption capacity of 101 mg/g. Both surface area and surface nitrogen had strong influences on the adsorption capacity of adsorbents. Mechanistically, physisorption interactions predominate the synergistic or antagonistic interaction between N-functionalized composites and herbicide species. These green adsorbent materials, fabricated from sustainable biopolymers, are promising candidates for diverse environmental remediation applications.

Author Keywords: adsorption, Environmental remediation, N-functionalization, O-functionalization, tropical hardwood waste, waste valorization

Forests play a critical role in the global carbon cycle, acting as carbon sinks that remove and store an estimated 0.4 to 4.1 Pg of atmospheric carbon annually. However, historical acid deposition and timber harvesting have disrupted nutrient cycles, leading to nutrient-deficient soils that hinder tree growth, particularly for sugar maple (Acer saccharum), a keystone species in Ontario sensitive to soil acidity and calcium (Ca) depletion. This study evaluates the effects of non-industrial wood ash (NIWA) applied at 0, 2, 4, 6, and 12 Mg ha-1 on soil chemistry, nutrient concentrations, microbial activity, CO2 fluxes, and sugar maple growth over two years. NIWA increased soil pH and exchangeable base cations, especially in the organic horizon, with some increase in forest floor metals, though foliar levels remained safe. Enzyme activity responses were minimal, and fine root biomass declined at higher doses. Soil CO₂ fluxes rose sharply at 12 Mg ha⁻¹, suggesting pH-driven effects. NIWA improves soil chemistry, but long-term impacts remain uncertain.

Author Keywords: carbon flux, extracellular soil enzyme, non-industrial wood ash, sugar maple