Graduate Theses & Dissertations

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It's All in Your Head
The Continuity Hypothesis states that dreams reflect waking day cognition and experiences, which reflect one’s mental health status. As such, dreams are, by extension, cognitions that occur during sleep. To date, Cognitive Behavioural Therapy (CBT) is deemed the most efficacious method of social anxiety treatment by working with cognitions. The current study utilized both CBT and The Storytelling Method (TSM) of dream interpretation, whose methodology is based on CBT; CBT works with waking cognitions and TSM works with sleep cognition. This study examined the effectiveness in decreasing social anxiety symptoms with TSM and comparing its efficacy to a traditional CBT technique. Undergraduate psychology students (N = 36) completed a daily journal of either the TSM or CBT format for two weeks. Participants completed self-report measures of social anxiety, state-anxiety, and depression before and after practicing either method. TSM did not significantly decrease levels of social anxiety, state-anxiety, or depression, whereas CBT significantly decreased only social anxiety levels. Dream content reflecting waking day anxiety and depression did not decrease over time, coinciding with the findings that students did not experience a decrease in their waking day life, supporting the Continuity Hypothesis. Findings suggest anxiety and depression to be very stable in this sample. Future research should explore interventions that are clinician-guided, in a group setting, or, occur over a longer period of time. Author Keywords: Content Analysis, Social anxiety, The Storytelling Method
Influence of Nitrogen Deposition on Community Composition in Pinus banksiana Forests Across Northwestern Canada
Anthropogenic atmospheric emissions and subsequent deposition of nitrogen (N) can affect N-sensitive habitats and lead to shifts in plant species community composition. This study assessed the effects of N deposition on plant community composition for Jack pine forests across northwestern Canada and across a smaller subset of sites surrounding the Athabasca Oil Sands Region (AOSR) using ‘gradient forest’ analysis. Predictor influence on community composition varied depending on the scale of the study and relatively distinct thresholds were identified for different plant groups. In the larger scale study, a total deposited nitrogen (TDN) threshold of 1.5 – 3 kg N ha-1yr-1 was well suited to protect predominantly lichen species, consistent with lichen-based critical loads from other studies. Across the smaller scale study, a TDN threshold of 5.6 kg N ha-1yr-1 was primarily associated with vascular species changepoints but did include some important N-indicator lichen and bryophyte species. Author Keywords: critical loads, gradientForest, Jack pine, Nitrogen deposition, species composition
Heavy Rydberg Photo-dissociation Cross-section Calculations and Experimental Progress Towards Cold Collisions in Lithium
This thesis is divided into two parts, each of which supports constructing and using a lithium magneto-optical trap for cold collision studies: Part I One outgoing channel of interest from cold collisions is the production of ion pairs. We describe an effective method for calculating bound-to-continuum cross-sections for charged binary systems by examining transitions to states above the binding energy that become bound when the system is placed within an infinite spherical well. This approach is verified for ionization of a hydrogen atom, and is then applied to the heavy Rydberg system Li+...I-. Part II A wavemeter previously built in the lab is redesigned for increased reliability and ease of use by replacing the optical hardware with a rocker system, which can be aligned in mere minutes rather than half a day as was previously the case. The new wavemeter has been tested through saturated absorption spectroscopy of lithium. Author Keywords: cross-section, dissociation, lithium, magneto-optical trap, Michelson, wavemeter
HABITAT SELECTION AND LIFE-HISTORY TRAITS OF BREEDING BIRDS IN THE BOREAL-TUNDRA ECOTONE, WITH SPECIAL ATTENTION TO THE AMERICAN ROBIN (TURDUS MIGRATORIUS)
I investigated biodiversity of birds and vegetation associations along the boreal-tundra ecotone in Ivvavik National Park, Yukon Territory, and breeding adaptations used by American Robins (Turdus migratorius) at high latitudes. Twenty bird species were detected over three years using point-count surveys. Densities of American Robin, Dark-eyed Juncos (Junco hyemalis), and Yellow-rumped Warbler (Dendroica coronata) had positive relationships with tree and shrub density, whereas density of White-crowned Sparrows (Zonotrichia leucophrys) was negatively related to tree density. American Robins at this latitude raised only one brood, but females laid slightly larger clutches, the young fledged earlier, and pairs experienced higher nest-success than American Robins at more southerly latitudes. American Robins selected nest sites with high vegetation volume, at both the nest-site, and the nest-patch. This study is important for the first description of the bird community at this high latitude location, and describing how a species at the northern limit of the boreal forest has adapted to living with short-breeding seasons. Author Keywords: American Robin, Ivvavik National Park, Life History, Nest-stie selection, Northern limit
Effect of Carbon Source and Phytohormones on the in vitro Growth of Euglena Gracilis
Microalgae are a promising source of valuable compounds relevant to biofuels, biomaterials, nutraceuticals as well as animal and human nutriment. Unfortunately, low cell density and slow growth result in reduced economic feasibility. Heterotrophic cell culturing using an organic carbon source in lieu of light has proven to be an effective alternative to photobioreactors; however, further improvement may be possible with the addition of growth promoting phytohormones. In this thesis, growth and endogenous hormone profiles in heterotrophic cultures of Euglena gracilis were evaluated using glucose and ethanol as carbon sources. Cytokinin (CK) and abscisic acid (ABA) were quantified by HPLC-ESI-MS/MS and compared to culture growth dynamics. Exogenous phytohormones treatments were also conducted to determine if they may mitigate nutrient reduction and improve growth. Phytohormones CK and ABA were purified and analyzed at seven points along the growth curve in small scale (250 mL flasks, 100 mL working volume) cultures. Among the key findings was that ethanol cultures undergoing exponential growth, primarily synthesize freebase cytokinins (FBCKs) and methylthiol-cytokinins (MeSCKs), while not producing detectable levels of ABA. In exogenous studies, dry biomass was positively influenced with the addition of exogenous ABA; however, the most notable result revealed the ability of transZ to alleviate nutrient reduction. These findings suggest a communication network in algal culture using FBCKs and MeSCKs, as well as the potential for exogenous hormone supplementation to increase growth rates and overall biomass productivity. Author Keywords: abscisic acid, cytokinin, Euglena gracilis, heterotrophy, phytohormones
impact of selection harvesting on soil properties and understory vegetation in canopy gaps and skid roads in central Ontario
Tree harvesting alters nutrient cycling and removes nutrients held in biomass, and as a result nutrient availability may be reduced, particularly in naturally oligotrophic ecosystems. Selection harvesting is a silvicultural technique limited to tolerant hardwood forests where individual or small groups of trees are removed creating a “gap” in the forest canopy. In order for harvesting machinery to gain access to these individual trees, trees are felled to create pathways, known as skid roads. The objective of this study was to characterize differences in soil chemical and physical properties in gaps, skid roads and uncut areas following selection harvesting in central Ontario as well as documenting differences in the understory vegetation community and sugar maple (Acer saccharum) seedlings chemical composition post harvest. First year seedlings were collected for elemental analysis from unharvested areas, canopy gaps, and skid roads in 2014, eight months after harvesting. In 2015, first and second year sugar maple seedlings were collected. Soil bulk density and water infiltration were measured in the three areas of the catchment as well as soil moisture, organic matter content, exchangeable base cations, and net nitrification. Seedlings in the disturbed sites had lower concentrations of Mg, K, P, and N compared with unharvested sites and soil nitrification was significantly lower in the skid roads. Water infiltration rates in the gap and skid roads were slower than the control and concentrations of metals (e.g. Fe, Al, Ca) and litter mass increased in litter bags deployed over 335 days, likely reflecting an increase in soil erosion in the skid roads. Understory vegetation was markedly different amongst sites, particularly the dominance of Carex spp. in the skid roads. The sustainability of industrial logging is dependent on successful tree regeneration, however, increased soil compaction, establishment and growth of grasses and shrubs, as well as low nutrient concentrations in seedlings may ultimately restrict forest succession. Author Keywords: Canadian Shield, nitrification, selection harvesting, soil compaction, sugar maple seedling, understory vegetation
Tool-use and near-tool effects
After active tool-use visual stimuli near a tool are processed more quickly and accurately than those farther away from a tool. Can these near-tool effects be modulated by training demands? To investigate this we asked the participants to complete a tool training task followed by a cross-modal interference task. During the training task the participants performed quick and accurate pointing movements to reach a strict or moderate criterion. The results indicated that the strict group made faster movements than the moderate group. During the cross-modal interference task visual distractors were presented along handheld tools in conjunction with vibrotactile stimuli on the hand. No significant compatibility effects were found for visual distractors near the hand or tool tip, and no consistent group differences were found. Our findings demonstrate the importance of using a novel tool during training, and that virtual stimuli may not be effective to elicit near-tool effects. Author Keywords: bimodal neurons, cross-modal interference, near-tool effects, tool training, training demands
Cognitive and Affective Theory of Mind in Children and Young Adolescents
Recently, a distinction has been made between cognitive theory of mind, the ability to make inferences about other's beliefs and thoughts, and affective theory of mind, the ability to make inferences about other's emotional states. The purpose of this study is to determine if the distinction between cognitive and affective theory of mind is developmentally appropriate and whether the relation between language and theory of mind is maintained when cognitive and affective theory of mind are examined separately. The sample consisted of 20 children aged 6 to 9 years, and 27 children aged 11 to 15 years. Results showed that the older group outperformed the younger group on both cognitive and affective theory of mind, and that different aspects of language were related to each type of theory of mind. This suggests the distinction between cognitive and affective theory of mind may in fact be valid in this age range. Author Keywords: Affective Theory of Mind, Cognitive Theory of Mind, Development, Language
Investigating the regional variation in frequencies of the invasive hybrid cattail, Typha × glauca
Interspecific hybridization rates can vary depending on genomic compatibilities between progenitors, while subsequent hybrid spread can vary depending on hybrid performance and habitat availability for hybrid establishment and persistence. As a result, hybridization rates and hybrid frequencies can vary across regions of parental sympatry. In areas around the Laurentian Great Lakes, Typha × glauca is an invasive plant hybrid of native Typha latifolia and introduced Typha angustifolia. In areas of parental sympatry in Atlantic Canada and outside of North America, T. × glauca has been reported as either rare or non-existent. I investigated whether the low frequencies of hybrids documented in Nova Scotia, Atlantic Canada, are influenced by reproductive barriers that prevent hybrid formation or environmental factors (salinity) that reduce hybrid performance. I identified an abundance of hybrids in the Annapolis Valley (inland) and a scarcity of hybrids in coastal wetlands through preliminary site surveys throughout Nova Scotia. In Annapolis Valley populations, flowering times of progenitor species overlapped, indicating that asynchronous flowering times do not limit hybrid formation in this region. Viable progeny were created from interspecific crosses of T. latifolia and T. angustifolia from Nova Scotia, indicating that there are no genomic barriers to fertilization and germination of hybrid seeds. Typha × glauca germination in high salinity was significantly lower than that of T. latifolia, but there was no difference at lower salinities. Therefore, while germination of hybrid seeds may be impeded in the coastal wetlands where salinity is high, inland sites have lower salinity and thus an environment conducive to hybrid germination. However, I found that once established as seedlings, hybrids appear to have greater performance over T. latifolia across all salinities through higher ramet production. Moreover, I found that T. latifolia sourced from Ontario had reduced germination and lower survivorship in high salinities compared to T. latifolia sourced from Nova Scotia, which could indicate local adaptation by T. latifolia to increased salinity. These findings underline that interactions between environment and local progenitor lineages can influence the viability and the consequent distribution and abundance of hybrids. This, in turn, can help explain why hybrids demonstrate invasiveness in some areas of parental sympatry but remain largely absent from other areas. Author Keywords: flowering phenology, Hybridization, invasive species, physiology, pollen compatibility, salinity tolerance
Facilitating Self-Regulation through Physical Activity
Self-regulation skills have been connected to positive school success and increased academic achievement (McClelland, Acock, & Morrison, 2006). One recently explored method to aid students in their ability to self-regulate is physical activity (Becker, et al., 2011). The purpose of this study was to explore the facilitation of self- regulation through physical activity via access to an exercise bicycle within an elementary and secondary school setting. Student bicycle usage was explored via student documentation to determine frequency and duration of use. Teacher observations were collected via email correspondence were analyzed via thematic content analysis and reflections made by the teachers at a follow-up debriefing session were summarized. Overall, a novelty effect was apparent with the bicycle, where it was used extensively in the first month of the study and then use sharply declined thereafter. Teachers felt that the bicycle appeared to provide some students with support, however there were challenges with integrating the exercise bicycle into the classroom. As well, teachers stated that factors such as bicycle placement and engagement levels must be explored further in order to understand the impact an exercise bicycle could possibly have on a student’s ability to self-regulate. Author Keywords: exercise bicycle, physical activity, self-regulation
Investigation of Using Phase Change Materials for Thermal Energy Storage in Adiabatic Compressed Air Energy Storage
There is an increasing global need for grid scale electrical energy storage to handle the implementation of intermittent renewable energy sources. Adiabatic compressed air energy storage is an emerging technology with similar performance to pumped hydro except it has the issue of heat loss during the compression stage. Previously, it has been considered to use sensible heat storage materials to store the heat created by compression in a thermal energy storage unit until energy is required, and then transfer the heat back to the air. This research proposes to instead use phase change materials to store the heat of compression, as this will reduce entropy generation and maximize roundtrip exergy efficiency. Different configurations and placements of the phase change materials are considered and exergy analyses are presented. The thermodynamic equations are derived and optimal setup conditions including amount of latent heat and melting temperatures are calculated. Author Keywords: Compressed Air Energy Storage, Energy Storage, Exergy, Phase Change Materials
Gratitude is in our nature
Although a wealth of research supports nature’s beneficial effects on well-being, a lack of attentiveness and appreciation for nature may prevent people from fully experiencing nature’s benefits. A mindfulness-based nature intervention was tested across two studies to investigate whether gratitude and mindfulness can boost nature’s effects for well-being. Students completed activities across a one-week (Study 1; N = 129) and two-week (Study 2; N = 130) intervention. Students in both studies experienced significant declines in positive and negative emotion over time. Study 1 did not show the expected increases in gratitude and connection to nature. Study 2 found that students who simply spent time in nature experienced fewer negative emotions and greater increases in trait gratitude than those who were asked to gratefully reflect on their natural surroundings. Both studies found positive correlations between trait gratitude, mindfulness, well- being and connection to nature. Implications and suggestions for future research are discussed. Author Keywords: Gratitude, Intervention, Mental Heath, Mindfulness, Nature, Well-being

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Graduate student theses produced at Trent University. You may also browse theses and dissertations by year, program, or author.

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