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Investigation Of The Impact-Generated Hydrothermal System At The West Clearwater Lake Impact Structure, Quebec, Canada, Juan Pablo Jaimes Bermudez

Electronic Thesis and Dissertation Repository

Hypervelocity impact cratering is a ubiquitous and fundamental geologic process that shapes the surface of all solid bodies in the solar system. Despite its catastrophic consequences, it has been shown that under the presence of H₂O (liquid or frozen), a heat source, and a permeable substrate, transient impact-generated hydrothermal systems may develop. These hydrothermal systems can alter the mineralogical and geochemical characteristics of the host rocks. Moreover, they provide insight into planetary habitability and past climates, which makes impact craters prime exploration targets on other solid bodies, particularly Mars. Understanding the processes and conditions (temperature, pressure, salinity, pH, …

Structural Dynamics Of A Thermally Stressed Monoclonal Antibody Characterized By Temperature-Dependent H/D Exchange Mass Spectrometry., Nastaran N Tajoddin, Lars Konermann

Chemistry Publications

Differential scanning calorimetry (DSC) is a standard tool for probing the resilience of monoclonal antibodies (mAbs) and other protein therapeutics against thermal degradation. Unfortunately, DSC usually only provides insights into global unfolding, although sequential steps are sometimes discernible for multidomain proteins. Temperature-dependent hydrogen/deuterium exchange (HDX) mass spectrometry (MS) has the potential to probe heat-induced events at a much greater level of detail. We recently proposed a strategy to deconvolute temperature-dependent HDX data into contributions from local dynamics, global unfolding/refolding, as well as chemical labeling. However, that strategy was validated only for a small protein (Tajoddin, N. N.; Konermann, L.

Measuring The Exposure And Vulnerability Of Transit Riders To Cold Temperatures In London, Ontario, Armin Mahboubi

Undergraduate Student Research Internships Conference

Due to the expansion of suburban areas in many cities around the world, accessibility to public transit through walking has become a new challenge for riders. Considering the impacts of climate change in creating more extreme weather, such as extreme cold, heat, or flooding, transit riders may thus be at a higher risk of exposure for various weather-related illnesses (Fraser & Chester, 2016).

Using ArcGIS Pro and ArcMap software, and data collected from City of London’s Open Portal, the United States Geological Survey, Open Mobility Data, and Statistics Canada, the exposure and vulnerability of transit riders to cold temperatures in …

Mechanism Of Thermal Protein Aggregation: Experiments And Molecular Dynamics Simulations On The High-Temperature Behavior Of Myoglobin., Yuen Ki Ng, Nastaran N Tajoddin, Pablo M Scrosati, Lars Konermann

Chemistry Publications

Proteins that encounter unfavorable solvent conditions are prone to aggregation, a phenomenon that remains poorly understood. This work focuses on myoglobin (Mb) as a model protein. Upon heating, Mb produces amorphous aggregates. Thermal unfolding experiments at low concentration (where aggregation is negligible), along with centrifugation assays, imply that Mb aggregation proceeds via globally unfolded conformers. This contrasts studies on other proteins that emphasized the role of partially folded structures as aggregate precursors. Molecular dynamics (MD) simulations were performed to gain insights into the mechanism by which heat-unfolded Mb molecules associate with one another. A prerequisite for these simulations was the …

Cellulose Biodegradability And Its Impact On Enhanced Biological Phosphorus Removal, Moustafa Ibrahim Elbahrawi

Electronic Thesis and Dissertation Repository

Cellulose from toilet paper contributes approximately one third of the influent organic suspended solids (TSS) to wastewater treatment plants and is a key target for resources recovery. Cellulose recovery is beneficial as it reduces the required energy for treatment and biosolids treatment cost. Hence, understanding the hydrolysis of cellulose in wastewater which is mainly affected by temperature and the solids retention time (SRT), is a major key to determine the optimum location for its recovery. In order to assess the impact of temperature and SRT on cellulose degradation, this study investigated the biological aerobic degradation of cellulose in four laboratory-scale …

Examining Weather-Related Factors On Physical Activity Levels Of Children From Rural Communities, Brenton L.G. Button, Tayyab I. Shah, Andrew F. Clark, Piotr Wilk, Jason A. Gilliland

Paediatrics Publications

Objective: The objective was to examine the influence of weather on moderate-to-vigorous physical activity (MVPA) and light physical activity (LPA) levels of children aged 8–14 years from rural communities, an understudied Canadian population. Methods: Children (n = 90) from four communities in rural Northwestern Ontario participated in this study between September and December 2016. Children’s MVPA and LPA were measured using an Actical accelerometer and demographic data were gathered from surveys of children and their parents. Weather data were collected from the closest weather station. Cross-classified regression models were used to assess the relationship between weather and children’s MVPA and …

Examining Weather-Related Factors On Physical Activity Levels Of Children From Rural Communities, Brenton L.G. Button, Tayyab I. Shah, Andrew F. Clark, Piotr Wilk, Jason A. Gilliland

Paediatrics Publications

Objective: The objective was to examine the influence of weather on moderate-to-vigorous physical activity (MVPA) and light physical activity (LPA) levels of children aged 8–14 years from rural communities, an understudied Canadian population. Methods: Children (n = 90) from four communities in rural Northwestern Ontario participated in this study between September and December 2016. Children’s MVPA and LPA were measured using an Actical accelerometer and demographic data were gathered from surveys of children and their parents. Weather data were collected from the closest weather station. Cross-classified regression models were used to assess the relationship between weather and children’s MVPA and …

Thermoresponsive Self-Immolative Polyglyoxylamides., Amir Rabiee Kenaree, Quinton E. A. Sirianni, Kyle Classen, Elizabeth R. Gillies

Chemistry Publications

Thermoresponsive polymers with lower critical solution temperatures (LCSTs) are of significant interest for a wide range of applications from sensors to drug delivery vehicles. However, the most widely investigated LCST polymers have nondegradable backbones, limiting their applications

Analysis Of Temperature-Dependent H/D Exchange Mass Spectrometry Experiments., Nastaran N Tajoddin, Lars Konermann

Chemistry Publications

H/D exchange (HDX) mass spectrometry (MS) is a widely used technique for interrogating protein structure and dynamics. Backbone HDX is mediated by opening/closing (unfolding/refolding) fluctuations. In traditional HDX-MS, proteins are incubated in D₂O as a function of time at constant temperature (T). There is an urgent need to complement this traditional approach with experiments that probe proteins in a T-dependent fashion, e.g., for assessing the stability of therapeutic antibodies. A key problem with such studies is the absence of strategies for interpreting HDX-MS data in the context of T-dependent protein dynamics. Specifically, it has …

Investigating The Role Of Carbon Stress In The Mortality Of Tamarack Seedlings Under A Warming Environment, Bridget K. Murphy

Electronic Thesis and Dissertation Repository

Climate warming is increasing the frequency of climate-induced tree mortality events. While drought combined with heat is considered the primary cause of this tree mortality, little is known about whether high temperatures alone can induce mortality, or whether rising CO₂ will increase survival. I grew tamarack in two experiments combining warming (0-8 ˚C above ambient) and CO₂ (400-750 ppm) to investigate whether high growth temperatures led to carbon limitations and mortality. Using glasshouses, +8 ˚C warming with ambient CO₂ (8TAC) led to 40% mortality despite thermal acclimation of respiration. Dying 8TAC seedlings had lower needle carbon concentrations …

Effects Of Elevated Temperature And Elevated Co2 On Leaf Carbon Fluxes In Boreal Conifers: Lab And Field Studies, Mirindi Eric Dusenge

Electronic Thesis and Dissertation Repository

Rising CO₂ may warm northern latitudes up to 10 °C by the end of the century. However, responses of plant physiological processes (such as photosynthesis and respiration) and growth to climate change remain uncertain. Seedlings and mature trees of tamarack (a deciduous species) and black spruce (an evergreen species), North America dominant conifers, were exposed to combined warming (up to +9 ˚C) and elevated CO₂ (up to +300 ppm). In seedlings, stomatal conductance (g_s) tended to increase with warming in tamarack seedlings, while g_sdeclined with warming in spruce. In both species, CO₂ had …

Analyzing Avian Incubation With A Computer Algorithm, Tanya T. Shoot

Electronic Thesis and Dissertation Repository

A stable nest environment is necessary for incubation and development of offspring. Birds vary behaviour to regulate temperature for successful hatchlings. I used a hidden Markov model (HMM) to test how environmental conditions affect incubation behaviour. I examined nest temperatures and behaviours collected from Zebra finches that incubated at 30 °C or 14 °C, then incubated in the same or opposite condition for a second clutch. Data loggers and cameras recorded nest temperature and number of parents on nest. The HMM inferred behaviour from recorded behaviours and temperatures. Temperature and offspring success affected incubation duration. Birds that had successful offspring …

Future Changes Of Hydroclimatic Extremes In Western North America Using A Large Ensemble: The Role Of Internal Variability, Mohammad Hasan Mahmoudi

Electronic Thesis and Dissertation Repository

Increases in the intensity and frequency of extreme events in Western North America (WNA) can cause significant socioeconomic problems and threaten existing infrastructure. In this study we analyze the impacts of climate change on hydroclimatic extremes and assess the role of internal variability over WNA, which collectively drain an area of about 1 million km². We used gridded observations and downscaled precipitation, maximum and minimum temperature from seven General Circulation Models (GCMs) that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) and a large ensemble of CanESM2 model simulations (CanESM2-LE; 50 members) for this analysis. Spatial …

Thermal Biology Of Temperate And High-Latitude Arachnids, Susan E. Anthony

Electronic Thesis and Dissertation Repository

Temperate and high latitude terrestrial ecosystems have high thermal variability, and the ectotherms that inhabit these regions must have thermal tolerances that mirror these temperatures. However, the thermal limits of many high-latitude arachnids are unknown, as well as any underlying mechanisms of seasonal plasticity for any arachnid. The objective of my thesis is to measure the thermal tolerances of temperate, Arctic, and sub-Arctic arachnids, and identify if they have thermal plasticity, either seasonally or following acclimation. I collected the high-latitude pseudoscorpion Wyochernes asiaticus streamside from the Yukon Territory, where besides large thermal variability, they are also inundated with spring flooding. …

Experimental Testing And Modeling Of Partial Nitrification At Different Temperatures, Xiaoguang Liu

Electronic Thesis and Dissertation Repository

Nitrogen in wastewater treatment plant effluents has adverse environmental effects on aquatic systems. Excessive concentrations of nitrogen in water bodies can result in the depletion of dissolved oxygen, deterioration of water quality, and shifts of biotic community. Conventional biological nitrogen removal (BNR) processes consume high energy for nitrification and require external carbon for denitrification. Alternatively, partial nitrification is of interest as an emerging technology for its lower need of organic carbon addition and cost savings in aeration. In this study, the main objectives are: 1- developing a mathematical model involving operational parameters for the determination of successful partial nitrification conditions; …

Growth And Toxicity Of Geographically-Distinct Isolates Of The Fish-Killing Phytoflagellate, Heterosigma Akashiwo, Veerta Singh

Electronic Thesis and Dissertation Repository

Harmful Algal Blooms (HABs)—an accumulation of toxic phytoplankton—often result from environmental changes reflecting the increasing global human footprint and climate change. One HAB species drawing attention is Heterosigma akashiwo, a fish-killing flagellate that can cause extensive fish loss or be benign, depending on location or environmental conditions. Here, I investigate if this difference in toxicity is regulated by environmental conditions or differences in cellular physiology. Six strains were examined. Three originate from the Salish Sea, where fish-kills are common, and three from Japan, where blooms of Heterosigma are common but fish-kills are rare. By measuring growth and toxicity of cells …

Effects Of Water Temperature, Rearing Temperature And Population On Swimming Performance And Temperature Preference In Atlantic Salmon (Salmo Salar), Nicole Zathey

Electronic Thesis and Dissertation Repository

Understanding how animals respond to environmental temperatures is important for the survival and reintroduction of species. My objectives were to determine how swim performance responds across water temperatures, and how rearing temperature or population would affect this performance and temperature preference. Juvenile Atlantic salmon (Salmo salar) from two populations that are currently used for stocking in Lake Ontario (LaHave, Sebago) were reared at two temperatures (11°C, 19°C). I measured critical swim speed and burst swim speed across eight water temperatures (11 – 25°C). Water temperature had no effect on burst speed, while critical swim speed increased with increased …

Elevated Temperature And Co2 Concentrations Affect Carbon Flux In Two Boreal Conifers, Sasha Madhavji

Electronic Thesis and Dissertation Repository

Elevated temperatures and CO₂ will alter carbon flux in two dominant boreal tree species Picea mariana (black spruce) and Larix laricina (tamarack). Trees were grown in three temperature treatments (ambient, ambient +4 °C, and ambient +8 °C) at either 400 ppm or 750 ppm CO₂, to simulate climate conditions between now and the year 2100. Spruce acclimated to increasing temperature detractively; warming scenarios reduced spruce net carbon gain. Tamarack maintained comparable levels of net photosynthesis (A_net) across warming treatments and both species acclimated respiration (R_dark) with increasing growth temperature. Elevated CO₂-grown …

Winter Warming Affects The Onset Of Reproduction But Not Cognition Or The Hippocampus In Black-Capped Chickadees (Poecile Atricapillus), Robert J. Martin

Electronic Thesis and Dissertation Repository

The effects of overwinter temperature on behaviour and cognition, hippocampal volume, and reproductive timing were studied in Black-capped chickadees (Poecile atricapillus). I hypothesized that overwinter temperature would have varied effects for Black-capped chickadees that overwinter in northern climates. I found that temperature had no effect on behaviour and cognition, or hippocampal volume, but temperature did influence reproductive timing. Birds that experienced warmer winter conditions had significantly more developed gonads than birds that experienced colder conditions. These results suggest that while birds are clearly sensitive to ambient winter temperature, temperature only modulates some processes and not all. These studies …

A Method For Hemispherical Ground Based Remote Sensing Of Urban Surface Temperatures, Michael A. Allen

Electronic Thesis and Dissertation Repository

This thesis presents a method for deriving time-continuous urban surface temperature and heat island assessments from hemispherical ground-based measurements of upwelling thermal radiation. The method, developed to overcome geometric and temporal biases inherent in traditional thermal remote sensing of urban surface climates, uses a sensor view model in conjunction with a radiative transfer code to derive atmospherically corrected, hemispherical radiometric urban surface temperatures. These are used to derive two long-term climatologies of surface urban heat island (sUHI) magnitudes for Basel, Switzerland and Vancouver, Canada. sUHI development shows significant variation based on time-of-day, season, and ambient and synoptic conditions. Results also …

Study On The Mechanical Behavior Of Directly Compounded Long Glass Fiber Reinforced Polyamide 6 Composites, Yuchao Liu

Electronic Thesis and Dissertation Repository

With great lightweight potential, high performance-to-cost ratio and mass productivity, direct-compounded long fiber thermoplastics (D-LFT) have drawn great attention from the automotive industry. With better mechanical properties and higher service temperature, polyamide 6 (PA6) was used to replace polypropylene (PP) which is almost the exclusively used matrix for the D-LFT process currently. The investigation was performed on this new material with a focus on the effect of fiber content, processing parameters, temperature and tailored reinforcement on mechanical behavior. The results show that the mechanical properties of this new material are sensitive to the variation of fiber content and service temperature …

Experimental Studies Of Electrical Resistivity Behavior Of Cu, Zn And Co Along Their Melting Boundaries: Implications For Heat Flux At Earth’S Inner Core Boundary, Innocent Chinweikpe Ezenwa

Electronic Thesis and Dissertation Repository

Abstract

The electrical resistivity of high purity Cu, Zn and Co has been measured at pressures (P) up to 5GPa and at temperatures (T) in the liquid phase. The electrical resistivity of solid state Nb was also measured up to 5GPa and ~1900K. All measurements were made in a large volume cubic anvil press. Using two thermocouples placed at opposite ends of the sample wire, serving as temperature probes as well as resistance leads, a four-wire technique resistivity measurement was employed along with a polarity switch. Post-experiment compositional analyses were carried out on an electron microprobe.

The expected resistivity decrease …

Paradoxical Acclimation Responses In The Thermal Performance Of Insect Immunity., Laura V Ferguson, David E Heinrichs, Brent J Sinclair

Biology Publications

Winter is accompanied by multiple stressors, and the interactions between cold and pathogen stress potentially determine the overwintering success of insects. Thus, it is necessary to explore the thermal performance of the insect immune system. We cold-acclimated spring field crickets, Gryllus veletis, to 6 °C for 7 days and measured the thermal performance of potential (lysozyme and phenoloxidase activity) and realised (bacterial clearance and melanisation) immune responses. Cold acclimation decreased the critical thermal minimum from -0.5 ± 0.25 to -2.1 ± 0.18 °C, and chill coma recovery time after 72 h at -2 °C from 16.8 ± 4.9 to 5.2 …

Paradoxical Acclimation Responses In The Thermal Performance Of Insect Immunity., Laura V Ferguson, David E Heinrichs, Brent J Sinclair

Biology Publications

Winter is accompanied by multiple stressors, and the interactions between cold and pathogen stress potentially determine the overwintering success of insects. Thus, it is necessary to explore the thermal performance of the insect immune system. We cold-acclimated spring field crickets, Gryllus veletis, to 6 °C for 7 days and measured the thermal performance of potential (lysozyme and phenoloxidase activity) and realised (bacterial clearance and melanisation) immune responses. Cold acclimation decreased the critical thermal minimum from -0.5 ± 0.25 to -2.1 ± 0.18 °C, and chill coma recovery time after 72 h at -2 °C from 16.8 ± 4.9 to 5.2 …

Similar Metabolic Rate-Temperature Relationships After Acclimation At Constant And Fluctuating Temperatures In Caterpillars Of A Sub-Antarctic Moth., Steven L Chown, Tanya M Haupt, Brent J Sinclair

Biology Publications

Temperature compensation in whole-animal metabolic rate is one of the responses thought, controversially, to characterize insects from low temperature environments. Temperature compensation may either involve a change in absolute values of metabolic rates or a change in the slope of the metabolic rate - temperature relationship. Moreover, assessments of compensation may be complicated by animal responses to fluctuating temperatures. Here we examined whole animal metabolic rates, at 0 °C, 5 °C, 10 °C and 15 °C, in caterpillars of the sub-Antarctic moth, Pringleophaga marioni Viette (Tineidae), following one week acclimations to 5 °C, 10 °C and 15 °C, and fluctuating …

Weather And Photoperiod Indices Of Autumn And Winter Dabbling Duck Abundance In The Mississippi And Atlantic Flyways Of North America, Lena M. Van Den Elsen

Electronic Thesis and Dissertation Repository

Climate change may influence autumn and winter distributions of dabbling ducks throughout the Atlantic and Mississippi Flyways of North America. To determine how weather and photoperiod influenced autumn-winter abundances of dabbling ducks at staging areas in eastern North America, I modeled weather and photoperiod variables with rate of change in relative abundance of various dabbling duck species over space and time. Latitude was incorporated into models to determine if changes in duck abundance in relation to weather severity were influenced by locale. Changes in abundance were best described by weather models incorporating temperature and snowfall variables for all species except …

Insects In Fluctuating Thermal Environments., Hervé Colinet, Brent J Sinclair, Philippe Vernon, David Renault

Biology Publications

All climate change scenarios predict an increase in both global temperature means and the magnitude of seasonal and diel temperature variation. The nonlinear relationship between temperature and biological processes means that fluctuating temperatures lead to physiological, life history, and ecological consequences for ectothermic insects that diverge from those predicted from constant temperatures. Fluctuating temperatures that remain within permissive temperature ranges generally improve performance. By contrast, those which extend to stressful temperatures may have either positive impacts, allowing repair of damage accrued during exposure to thermal extremes, or negative impacts from cumulative damage during successive exposures. We discuss the mechanisms underlying …

Nitrogen Fixation By The Cyanobacterium Nostoc Punctiforme In Response To Variation In Nitrogen Availability, Temperature, And Atmospheric Co2 Concentrations, Danielle A. Griffith

Electronic Thesis and Dissertation Repository

The predominant input of available nitrogen (N) in boreal forest ecosystems originates from moss-associated cyanobacteria, which fix unavailable atmospheric N₂, contribute to the soil N pool, and thereby support forest productivity. Although increases in N availability, temperature, and atmospheric CO₂ concentrations are expected in Canada’s boreal region over the next century, little is known about the combined effects of these factors on N₂ fixation by axenic cyanobacteria or the associated mechanisms. I assessed changes in N₂ fixation by Nostoc punctiforme under different global environmental change scenarios and examined correlations between the response and changes in …

Nasopharyngeal Method For Selective Brain Cooling And Development Of A Time-Resolved Near-Infrared Technique To Monitor Brain Temperature And Oxidation Status During Hypothermia, Mohammad Fazel Bakhsheshi

Electronic Thesis and Dissertation Repository

Mild hypothermia at 32-35^oC (HT) has been shown to be neuroprotective for neurological emergencies following severe head trauma, cardiac arrest and neonatal asphyxia. However, HT has not been widely deployed in clinical settings because: firstly, cooling the whole body below 33-34°C can induce severe complications; therefore, applying HT selectively to the brain could minimize adverse effects by maintaining core body temperature at normal level. Secondly, development of an effective and easy to implement selective brain cooling (SBC) technique, which can quickly induce brain hypothermia while avoiding complications from whole body cooling, remains a challenge. In this thesis, we …

The Plastic And Evolutionary Responses Of Fish To Anthropogenic Stressors, Ross D. Breckels

Electronic Thesis and Dissertation Repository

Ecosystems are being altered at unprecedented rates with little knowledge of the potential impacts on biodiversity. Two of the most pressing contemporary anthropogenic stressors are pollution and global warming. Species can respond to these stressors via dispersal, phenotypic plasticity, or evolutionary adaptation. Many species, especially aquatic organisms, experience ecological or physical barriers to dispersal and will therefore have to respond via phenotypic plasticity or evolutionary responses. I examined the responses of multiple traits associated with fitness in fish to pollution and increased temperature using a 2 × 2 common garden experimental design. I examined the effects of pollution on behaviour …