Graduate Theses & Dissertations

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ROOSTING SELECTION BEHAVIOUR OF THE EASTERN WILD TURKEY AT ITS NORTHERN RANGE EDGE
As wild turkeys (Meleagris gallopavo silvestris) move farther north, informed management decisions are critical to support the sustainability of this reintroduced species. We tracked roost tree selection and patterns of the network of roost trees, for wild turkeys, over 2 years in Peterborough, ON, using GPS and VHF transmitters. Wild turkeys showed preference for taller and larger roost trees, with winter roosts closer to buildings. The roost network exhibited a scale-free network, meaning certain roosts served as hubs, while other roosts were less frequently used. The fine scale results suggest that roost trees are selected for predator avoidance, and that selection changes with the season, probably because of its influence on foraging ability. At a larger scale, winter roosts were chosen for their proximity to supplemental food sources. These findings demonstrate the dependence of wild turkeys on humans and the supplemental sources we unintentionally provide. Author Keywords:
Executive Function, Emotion Regulation, and Social Problem Solving, in Adolescence and Early Adulthood
Research to date on social problem solving typically focuses on elementary school aged children. However, adolescents and young adults may experience more novel and emotionally complex social conflicts that require different skills to navigate them successfully. Previous research has highlighted executive function (EF) and emotion regulation as possible skills that help with social problem solving. The current study examined the potential relation between EF, emotion regulation, and social problem solving. The sample consisted of 174 participants with a mean age of 19.60 years. Results showed that the shifting component of EF was associated with being able to take different perspectives when coming up with a solution for a social conflict involving a romantic partner. Additionally, emotion regulation was associate with perspective taking in the overall social problem solving process with a romantic partner. These results suggest that both EF and emotion regulation are involved in the ability to take different perspectives during a social conflict in this age range. Author Keywords: Emotion Regulation, Executive Function, Social Problem Solving
Expression and characterization of cytochrome b5 from Giardia lamblia
Giardia lamblia is an intestinal parasite found globally in freshwater systems that is responsible for endemic outbreaks of infectious diarrhea. As a unicellular parasite that lacks mitochondria, a respiratory chain and lives in the anaerobic environment of its host's intestine, Giardia was assumed for decades to lack heme proteins. However, its genome encodes several putative heme proteins, including three with sequence similarity to the cytochrome b5 family, referred to as Giardia cytochromes b5 (gCYTb5). Recombinant expression of one of these genes (gCYTb5-I), results in a protein (17-kDa) that is isolated with noncovalently bound heme. Resonance Raman and UV-visible spectra of gCYTb5-I in oxidized and reduced states resemble those of microsomal cytochrome b5, while sequence alignment and homology modelling supports a structure in which a pair of invariant histidine residues act as axial ligands to the heme iron. The reduction potential of gCYTb5-I measured by cyclic voltammetry is -165 mV vs the standard hydrogen electrode and is relatively low compared to those of other family members. The amino- and carboxy-terminal sequences that flank the central heme-binding core of the gCYTb5 are highly charged and do not occur in other family members. An 11-kDa core gCYTb5-I variant lacking these flanking sequences was also able to bind heme; however, we observe very poor expression of this truncated protein as compared to the full-length protein. Author Keywords: b-type cytochrome, cytochrome b5, electron transfer protein, Giardia intestinalis, heme/heam protein, spectroelectrochemistry
Soil Geochemistry and Normative Mineralogy across Canada
Soils play a crucial role in ecosystem functioning, for example, soil minerals provide important provisioning and regulate ecosystem services. This study used major soil oxides from the North American Soil Geochemical Landscapes Project (n=560) to assess elemental associations and infer soil minerals through exploratory data analysis and to determined quantitative soil mineralogy using a normative method, Analysis to Mineralogy (n=1170). Results showed elemental variability of oxides across the provinces of Canada and strong correlations occurred between elements indicative of soil mineral composition (e.g., Silicon and Aluminium). Principal component analysis inferred soil minerals from soil oxides trends on biplots and classified minerals, generally, as carbonates, silicates, and weathered secondary oxides. Spatial variability in minerals (quartz, plagioclase, potassium feldspar, chlorite, and muscovite) was related to the underlying bedrock geology. The use of Analysis to Mineralogy led to a reliable method of quantifying soil minerals at a large scale. Author Keywords: Analysis to Mineralogy, Exploratory data analysis, Normative procedures, North American Soil Geochemical Landscapes Project, Soil geochemistry, Soil mineralogy
Effect of SP600125 JNK Inhibitor on Cadmium-Treated Mouse Embryo Forelimb Bud Cells In Vitro
This study investigated the role of the JNK signaling pathway in cadmium-treated mouse embryo forelimb bud cells in vitro. Primary cultures of forelimb bud cells harvested at day 11 of gestation were pre-treated with JNK inhibitor SP600125, and incubated with or without CdCl2 for 15, 30, 60, 120 minutes and 24, 48 hours or 5 days. Endpoints of toxicity were measured through cell differentiation by Alcian Blue Assay and phosphorylation of JNK proteins by Western blot. The results demonstrated that, in the cell differentiation assay, inhibiting JNK activation by 20 μM SP600125 causes an enhanced toxic effect in limb cells and inhibits cell differentiation, whereas 2 μM decreases differentiated nodule numbers under both cadmium stress and normal conditions. In conclusion, the JNK pathway has an essential role in the differentiation processes of limb bud cells in normal growth conditions. Author Keywords: Cadmium, Cell Signaling, JNK, Limbs, Mouse Embryo, Teratology
Cytokinin biosynthesis, signaling and translocation during the formation of tumors in the Ustilago maydis-Zea mays pathosystem
Cytokinins (CKs) are hormones that promote cell division. During the formation of tumors in the Ustilago maydis-Zea mays pathosystem, the levels of CKs are elevated. Although CK levels are increased, the origins of these CKs have not been determined and it is unclear as to whether they promote the formation of tumors. To determine this, we measured the CK levels, identified CK biosynthetic genes as well as CK signaling genes and measured the transcript levels during pathogenesis. By correlating the transcript levels to the CK levels, our results suggest that increased biosynthesis and signaling of CKs occur in both organisms. The increase in CK biosynthesis by the pathosystem could lead to an increase in CK signaling via CK translocation and promote tumor formation. Taken together, these suggest that CK biosynthesis, signaling and translocation play a significant role during the formation of tumors in the Ustilago maydis-Zea mays pathosystem. Author Keywords: Biosynthesis, Cytokinins, Signaling, Translocation, Ustilago maydis, Zea mays
Cluster Approach Applied to the One-Dimensional Anderson-Hubbard Model
S. Johri and R. Bhatt developed a real-space renormalization group approach aimed at extracting the localized single-particle eigenstates of the Anderson model from a large system by identifying clusters of resonant site potentials. E. Campbell generalized this real-space renormalization group approach using standard perturbation theory. Both approaches were intended to approximate the single-particle density of states of the Anderson model. In this thesis, we aimed to test the potential of applying a similar real-space renormalization group approach to calculate the density of states of the interacting Anderson-Hubbard model. Our interest in the density of states of this model is due to a V-shaped zero-bias anomaly in two-dimensional systems. A real-space renormalization group approach is best applied to a one-dimensional system. We found that the zero-bias anomaly is not V-shaped in one-dimension. To test the potential of a real-space renormalization group approach, we used the cluster approach which is the same as the non-interacting renormalization group approach but without the perturbation theory and found that for strong disorder this technique could accurately calculate the density of states over a wide range of energies but deviated from exact results at the band edge, at $\omega=\pm U$ and near $\omega=0$. The first two inaccuracies will be reduced with a proper real-space renormalization group approach. We suspect that the last inaccuracy is associated with long range physics and may be difficult to recover. We also developed a technique that adjusts the identification of clusters in the cluster approach to improve the computation time of the density of states with minimal loss of accuracy in a tunable range around the Fermi level. We found that this technique significantly reduced the computation time and was able to preserve the density of states near the Fermi level, except at the smallest energies near $\omega=0$. Author Keywords: Anderson-Hubbard model, renormalization group, Strong electron correlations, Zero-bias anomaly
Effects of Invasive Wetland Macrophytes on Habitat Selection by Turtles
Invasive species that alter habitats can have significant impacts on wildlife. The invasive graminoids Phragmites australis (Cav.) Trin. ex Steud, hereafter Phragmites, and Typha × glauca Godr. are rapidly spreading into North American wetlands, replacing native vegetation. Invasive Phragmites is considered a potential threat to several species-at-risk (SAR), including some turtle species. My study wetland contained large stands of Phragmites, as well as Typha spp. (including invasive T. × glauca) that have similar structural traits to Phragmites. To explore the hypothesis that Phragmites and Typha spp. do not provide suitable habitat for turtles, I tested the prediction that turtles avoid Phragmites- and Typha-dominated habitats. I used VHF-GPS transmitters to follow Blanding’s turtles (Emydoidea blandingii, n = 14) and spotted turtles (Clemmys guttata, n = 12). I found that both turtle species did not avoid Phragmites- or Typha-dominated habitats when choosing a home range, or while moving within their home range. I also tested whether the microhabitat selection of Blanding’s turtles and spotted turtles is affected by shoot density of Phragmites, Typha spp., or both. I compared shoot densities of Phragmites and Typha spp. in 4 m2 plots, from locations used by tracked turtles with paired, random locations in these turtles’ home ranges. For both turtle species, the densities of Phragmites and Typha shoots were comparable between used and random locations within the home ranges (generalized linear mixed model; p > 0.05). The use of Phragmites- and Typha-dominated habitats by Blanding’s turtles and spotted turtles suggests that these habitats do not automatically constitute “unsuitable habitats” for turtles. Phragmites and Typha spp. (especially T. × glauca) can replace preferred habitats of some turtle species, and the control of these invasive macrophytes can help to preserve habitat heterogeneity. However, the presence of SAR turtles in Phragmites and Typha spp. stands should inform risk-assessments for invasive plant species control methods that include mechanical rolling of stands, where heavy machinery might encounter turtles. Author Keywords: Blanding’s turtles, compositional analysis, habitat selection, Phragmites australis, spotted turtles, Typha x glauca
Relationship Between Precarious Employment, Behaviour Addictions and Substance Use Among Canadian Young Adults
This thesis utilized a unique data-set, the Quinte Longitudinal Survey, to explore relationships among precarious employment and a range of mental health problems in a representative sample of Ontario young adults. Study 1 focused on various behavioural addictions (such as problem gambling, video gaming, internet use, exercise, compulsive shopping, and sex) and precarious employment. The results showed that precariously employed men were preoccupied with gambling and sex while their female counterparts preferred shopping. Gambling and excessive shopping diminished over time while excessive sexual practices increased. Study 2 focused on the association between precarious employment and substance abuse (such as tobacco, alcohol, cannabis, hallucinogens, stimulants, and other substances). The results showed that men used cannabis more than women, and the non-precarious employed group abused alcohol more than individuals in the precarious group. This research has implications for both health care professionals and intervention program developers when working with young adults in precarious jobs. Author Keywords: Behaviour Addictions, Precarious Employment, Substance Abuse, Young Adults
Stability Properties of Disease Models under Economic Expectations
Comprehending the dynamics of infectious diseases is very important in formulating public health policies to tackling their prevalence. Mathematical epidemiology (ME) has played a very vital role in achieving the above. Nevertheless, classical mathematical epidemiological models do not explicitly model the behavioural responses of individuals in the presence of prevalence of these diseases. Economic epidemiology (EE) as a field has stepped in to fill this gap by integrating economic and mathematical concepts within one framework. This thesis investigated two issues in this area. The methods employed are the standard linear analysis of stability of dynamical systems and numerical simulation. Below are the investigations and the findings of this thesis: Firstly, an investigation into the stability properties of the equilibria of EE models is carried out. We investigated the stability properties of modified EE systems studied by Aadland et al. [6] by introducing a parametric quadratic utility function into the model, thus making it possible to model the maximum number of contacts made by rational individuals to be determined by a parameter. This parameter in particular influences the level of utility of rational individuals. We have shown that if rational individuals have a range of possible contacts to choose from, with the maximum of the number of contacts allowable for these individuals being dependent on a parameter, the variation in this parameter tends to affect the stability properties of the system. We also showed that under the assumption of permanent recovery for disease coupled with individuals observing or not observing their immunity, death and birth rates can affect the stability of the system. These parameters also have effect on the dynamics of the EE SIS system. Secondly, an EE model of syphilis infectivity among &ldquo men who have sex with men &rdquo (MSM) in detention centres is developed in an attempt at looking at the effect of behavioural responses on the disease dynamics among MSM. This was done by explicitly incorporating the interplay of the biology of the disease and the behaviour of the inmates. We investigated the stability properties of the system under rational expectations where we showed that: (1) Behavioural responses to the prevalence of the disease affect the stability of the system. Therefore, public health policies have the tendency of putting the system on indeterminate paths if rational MSM have complete knowledge of the laws governing the motion of the disease states as well as a complete understanding on how others behave in the system when faced with risk-benefit trade-offs. (2) The prevalence of the disease in the long run is influenced by incentives that drive the utility of the MSM inmates. (3) The interplay between the dynamics of the biology of the disease and the behavioural responses of rational MSM tends to put the system at equilibrium quickly as compared to its counterpart (that is when the system is solely dependent on the biology of the disease) when subjected to small perturbation. Author Keywords: economic and mathematical epidemiology models, explosive path, indeterminate-path stability, numerical solution, health gap, saddle-path stability, syphilis,
First Time…A Second Time
The purpose of the current study was to explore virginity loss experiences in lesbian, gay, and bisexual individuals (LGB), specifically those who have had both a sexual experience with a member of a different sex and a member of the same sex. This phenomenon is what the current study is defining as second virginity loss. Participants consisted of 645 LGB self-identified individuals, the sample was approximately half women (53%) and ages ranged from 18-65. Further, six semi-structured interviews were conducted to gain a clearer understanding of LGB individuals virginity loss experiences. Of the sample, approximately 60% of each sexual orientation reported having two sexual experiences they equated with virginity loss, one with a member of a different sex, and one with a member of the same sex. Analyses of both the qualitative and quantitative data were conducted in an attempt to gain an understanding in three main areas: (1) definitions of virginity loss, (2) virginity beliefs, and (3) motivations. It was found that LGB individuals continue to hold heteronormative definitions of virginity loss, i.e. penile-vaginal intercourse, though these definitions were found to be transitional in nature. LGB individuals also seem to hold more gift related beliefs toward their same-sex experience and more stigma related beliefs toward their different sex experience, however, as shown by previous research (Carpenter, 2001, 2002), most LGB individuals highly endorsed process beliefs. Finally, motivations for virginity loss were found to be consistent with two main themes: validation and drive. Overall, this research suggests that the LGB community has a fairly complicated relationship with virginity but certainly do not feel exempt from the concept or the pressures attached. The current study is the first to explore the phenomenon of second virginity loss in LGB individuals and should be used as a foundation for future research in both first sexual experience and LGB fields to build upon. Author Keywords: first sexual experience, LGB, mixed-methods, second virginity loss, virginity
Phosphorus forms and response to changes in pH in acid-sensitive soils on the Precambrian Shield
Catchment soil acidification has been suggested as a possible mechanism for reducing phosphorus (P) loading to surface waters in North America and northern Europe, but much of the research that has been conducted regarding P immobilization in pH manipulated soils has been performed at high P concentrations (> 130 μM). This study investigated how soil acidity was related to P fractionation and P sorption at environmentally relevant P concentrations to evaluate the potential influence of long term changes in soil pH on P release to surface waters. Total phosphorus (TP) concentrations declined between 1980 and 2000 in many lakes and streams in central Ontario; over the same time period forest soils in this region became more acidic. Soils were collected from 18 soil pits at three forested catchments with similar bedrock geology but varying TP export loads. The soil pH at the 18 study soil pits spanned the historic soil pH range, allowing for `space for time' comparison of soil P factions. Soils were analysed by horizon for P fractions via Hedley P fractionation. Batch P sorption experiments were performed on selected B-horizon soils at varied solution pH. Soil P fractions varied by horizon but were comparable among the three catchments, with only apatite (PHCl) differing significantly across catchments. Contrary to expectation, both soluble and labile P showed negative relationships with pH in some horizons. Mineral soils were able to sorb almost all (> 90 %) of the P in solution at environmentally relevant P concentrations (4.5 - 45.2 μM). Phosphorus sorption at environmentally relevant P concentrations was unrelated to solution pH but at high P concentration there was a positive relationship between P sorption and solution pH, suggesting a P concentration dependant P sorption mechanism. Phosphorus budgets indicate that P is accumulating within catchments, suggesting that P is being immobilized in the terrestrial environment. An alternative hypothesis, which attempts to explain both the decline in stream TP export and terrestrial P accumulation, is discussed. The results from this study suggest that acidification induced P sorption in upland soils are not a contributing factor to decreases in stream TP concentration in the study catchments. Author Keywords: central Ontario, Hedley fractionation, phosphorus, podzols, soil acidification, sorption

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