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Estimates Of Persistent Inward Current Decline In Human Soleus Motor Units During Fatigue, Kirby Mendes

Theses and Dissertations (Comprehensive)

Fatigue is defined as any exercise induced reduction in strength or power, and can be attributed to central and peripheral components. Many central and peripheral mechanisms have been extensively studied, but few studies have looked at the changes in the intrinsic properties of motor neurons and their contribution to fatigue. Persistent inward current (PIC) is an important intrinsic property of motor neurons responsible for setting a large increase in the gain of motor output and may contribute to fatigue. Inhibitory inputs such as reciprocal inhibition (RI) have been shown to turn off PICs and reducing the gain of output. PIC …

An Exploratory Approach To Manipulating Dynamic Stability: Investigating The Role Of Visual Control During A Precision Foot Placement Task, Russell Cg Kennedy

Theses and Dissertations (Comprehensive)

ABSTRACT

Background: The visual system provides the body with an accurate sensory system; designed to gather information at a distance and acts as a feedforward control mechanism during human locomotion. By doing so, visual information contributes coordination of the head-arm-trunk (HAT) segment and modulating foot placement. The purpose of this study was to examine the effects of a constrained pathway during a complex navigational stone-stepping task on HAT segment control and how the visual system guides locomotion during a complex foot placement task.

Methods: Nine university-aged females (Mean age: 22.5 years old +/-1.75) participated in this study. Participants …

The Effects Of External Focus Of Attention Exercise Rehabilitation On Dual Task Walking In Parkinson's Disease, Eric N. Beck

Theses and Dissertations (Comprehensive)

Parkinson’s disease impairs control of well-learned movements, and therefore, individuals with Parkinson’s disease are forced to walk with greater conscious control. This causes difficulties while walking and completing a secondary task simultaneously (dual tasking), in that distractions from conscious control of walking increase the risk of falls and injury. Although, attention-based exercise may be a potential avenue to decrease the demands associated with walking in Parkinson’s disease. For example, an external focus of attention (on manipulated objects) has been found to recruit the networks that are important for walking with little conscious control (automatic control networks). In contrast, an internal …

The Effects Of Manipulated Somatosensory Input On Simulated Falls During Walking, Sarah Mitchell-Ewart

Theses and Dissertations (Comprehensive)

Previous research has demonstrated that there is a distinct relationship between aging and instability. The somatosensory system plays a significant role in balance control in conjunction with vision and the vestibular system (Qiu et al., 2012). Evidence has shown that manipulation of the mechanoreceptors on the plantar surface of the foot has a direct effect on balance control. By manipulating these receptors with hypothermic anesthesia and vibration, researchers are capable of simulating the effect of sensory modification on healthy individuals, in order to understand the role that plantar-surface sensation has in adapting to perturbation during gait (Perry et al., 2001; …

The 2d:4d Ratio, Handedness, And Sex Across The Age Span, Helen A M Protopapas Ms.

Theses and Dissertations (Comprehensive)

The ratio of the difference between the 2nd and 4th digits of the hand (2D:4D ratio) has been demonstrated to be an indirect indicator of prenatal testosterone levels. Prenatal testosterone has been found to play a role in brain development in utero, and thus may influence lateral asymmetries, such as handedness. Consequently, one of the aims of the current study was to examine relationships between the 2D:4D ratio, hand preference, and hand performance with the factors of sex (males and females), handedness (right handers and left handers), and age considered. A total of 104 participants were tested, 90 right handers …

The Influence Of Hip Mobility And Fatigue On Spinal Flexion And Muscle Activation In Rugby Scrum Performance, Joshua D. Clayton

Theses and Dissertations (Comprehensive)

Introduction: Rugby scrumming is a means of restarting play following a minor rule infringement that can occur up to 28 times per game. The scrum poses a significant injury risk, with more days missed due to injury per event than any other rugby activity. Rugby players also have a significantly higher rate of spine injury than the general population, perhaps due to flexion in combination with high compression forces, which has been cited as the main mechanism of injury. Flexion of the spine has also been associated with poor hip mobility and quadriceps fatigue in other athletic tasks and may …

The Influence Of Joint-Site, Limb Preference, And Physical Activity On Joint Position Sense, Amanda N. Forsyth

Theses and Dissertations (Comprehensive)

Joint position sense provides the body with information about where limb segments are relative to one another in three-dimensional space. The ability to utilize this sense is imperative for smooth, coordinated, and accurate movement in everything from activities of daily living to competitive sport (Ghez & Sainburg, 1995). Researchers currently use joint position sense as a measure of proprioceptive acuity. However, limited research has investigated the influence of potential confounding factors on proprioception. Specifically, literature on how joint-site specificity and lateral preference influence proprioception displays several incongruent findings. Therefore, the purpose of the current study was (1) to determine if …

Changes In Brain Water Content In The Rainbow Trout (Oncorhynchus Mykiss) And In The Goldfish (Carassius Auratus) Due To High External Ammonia Exposure, Phillip Q.H. Pham-Ho

Theses and Dissertations (Comprehensive)

In fishes, hyperammonemia may occur following feeding or exposure to abnormally high concentrations of environmental ammonia due to sewage effluents, agricultural run-off and in crowded aquaculture pens. Increased internal ammonia can result in hyperactivity, convulsions, coma and death. In mammals, it is also associated with potentially fatal brain edema, in which the accumulation of intracellular water results in swelling, increased intracranical pressure and herniation leading to death. Recently it was shown that rainbow trout (Oncorhynchus mykiss) and goldfish (Carassius auratus) experience brain swelling following exposure to high external ammonia (HEA). However, the mechanism of ammonia-induced brain …

A Missing Link In The Ionoregulatory Strategy Of Larval Sea Lamprey (Petromyzon Marinus) And African Lungfish (Protopterus Annectens): A Closer Look Into The Role Of The Non-Gastric H+/K+-Atpase, Justine E. Doherty

Theses and Dissertations (Comprehensive)

Fishes living in freshwater need to actively compensate for the diffusive loss of ions and osmotic gain of water. The gill is the primary organ of ion regulation and contains an array of ion transport proteins to help maintain homeostasis. Two of the more well studied ion pumps are the Na⁺/K⁺-ATPase (NKA) and vacuolar type proton ATPase (V-ATPase). This thesis focuses on another ion pump known as the non-gastric H⁺/K⁺-ATPase (ngHKA). The ngHKA (gene: atp12a) has not been found in any of the teleost fishes, indicating loss from that lineage. In …

Mate Choice And Consequences For Consanguineous Mating In Drosophila Melanogaster, Emily S. Martin

Theses and Dissertations (Comprehensive)

The ability to discriminate between prospective mates is potentially important not only for the avoidance of unsuccessful or incompatible matings, but also for the selection of higher “quality” mates. Inbreeding, reproduction between closely related individuals, has long enjoyed the attention of biologists, and has classically been associated with fitness consequences that are primarily negative, termed “inbreeding depression”. Indeed, the costs of mating with a relative are well documented across a wide variety of species. If individuals are capable of kin recognition, it is expected that species should evolve to avoid consanguineous matings. However, a number of recent models suggest circumstances …

Sulfate-Reducing Bacteria Community Analysis: Isco/Isb Coupled Remediation, Christopher K. Bartlett

Theses and Dissertations (Comprehensive)

Improved techniques for remediating groundwater systems are required for the more than 500,000 contaminated sites in North America. Many of these sites are the legacy of historical industrial operations, inappropriate disposal practices and accidental releases. The most widely observed contaminant at many of these sites is petroleum hydrocarbons (PHCs). Recently, remediation efforts that involve the sequential application of treatment technologies have gained widespread interest. One specific sequential technology application or treatment train employs the aggressive nature of a chemical oxidation followed by bioremediation for polishing. When persulfate is used as the chemical oxidant its natural degradation by-product is sulfate, an …

Characterizing An Alternative Chloroplast Outer Membrane Targeting Signal In Arabidopsis Thaliana, Nicholas A. Grimberg

Theses and Dissertations (Comprehensive)

Chloroplasts are organelles that are unique to plant and algal cells and are the site of photosynthesis. Though chloroplasts contain their own genome, an estimated 95% of chloroplast proteins are encoded in the nucleus, and therefore rely on post-translational targeting to the organelle. The majority of known chloroplast proteins are targeted to the chloroplast interior by cleavable signals at the N-terminal end of preproteins known as transit peptides. The translocon at the outer envelope membrane of chloroplasts (Toc) is a multimeric complex that recognizes and binds N-terminal transit peptides at the cytosolic surface of chloroplasts. Though transit …

Do Toxicity Modifying Factors Influence Acute Or Chronic Toxicity Of Thulium To Hyalella Azteca?, Alexandria H. Loveridge

Theses and Dissertations (Comprehensive)

The industrial demand for rare earth elements (REEs) is growing and as a result, environmental exposure is a concern. Very little is understood about the toxicity of REEs in aquatic environments. The objective of this research is to evaluate the acute and chronic toxicity of Tm and to also understand the toxicity modifying influence of dissolved organic matter (DOM) and cationic competition (Ca2+, Mg2+ and Na+). Furthermore, the aim of this study was to determine linkages between Tm bioaccumulation, growth and survival during chronic exposures. Standard methods (Environment Canada) were followed for both 96h acute and 14d chronic tests, in …

The Feasibility, Practicality And Uses Of Detecting Crop Water Stress In Southern Ontario Apple Orchards With A Uas, Thomas S. Tiidus Mr.

Theses and Dissertations (Comprehensive)

UAS (Unmanned Aerial Systems) are becoming more common place in agricultural sites around the world. While the accuracy of achieving NDVI (Normalized Difference Vegetation Index) from a UAS is well understood, few studies have attempted to acquire other plant health attributes such as CWSI (Crop Water Stress Index), particularly in horticulture such as apple orchards. In addition, no academic studies up to the time of this writing have explored the perceived usefulness of data obtained from a UAS for the average farmer. This study explored the practicality and feasibility of using UAS for apple orchards in Southern Ontario. This study …

Causes And Consequences Of Variation In Female Mate Choice And Its Relation To Sexual Conflict In Drosophila Melanogaster, David Cs Filice

Theses and Dissertations (Comprehensive)

Female mate choice is a significant driving force of evolutionary change and can explain the evolution of exaggerated male traits and/or displays, and dimorphism between the sexes. Females are thought to choose mates based on the greatest provision of direct or indirect benefits. Despite this, we often still see substantial individual variation in female mate choice behaviours both within and across populations. Recent studies suggest that female mate choice is a complex decision-making process that involves many context-dependent factors. However, the precise sources of this variation, such as previous mating experience, are not completely understood. In Drosophila melanogaster, mating …

Characterization Of A Phosphonate-Specific Cytidylyltransferase, Kissa Batul

Theses and Dissertations (Comprehensive)

Antibiotic resistance is a major global health concern that requires new therapeutic approaches. Furthermore, a lack of narrow spectrum antibiotics on the market produces unintended consequences with respect to changes in our microbial make up. Phosphonates are reduced versions of phosphates that possess a C-P bond which is more resistant to enzymatic and chemical degradation. The role of phosphonate containing macromolecules (e.g. cell surface polysaccharides) remains enigmatic, however their presence suggests that they may confer an advantage. The biosynthesis of phosphonate-containing macromolecules is unknown, but a pathway is proposed involving aLicC type cytidylyltransferase-catalyzed conjugation to a phosphonate followed by a …

Metabolic Scaling Physiology And The Uptake, Elimination And Toxicity Of Tfm (3-Trifluoromethyl-4-Nitrophenol) To Invasive Sea Lampreys (Petromyzon Marinus), Laura R. Tessier

Theses and Dissertations (Comprehensive)

Sea lampreys (Petromyzon marinus) have a complex life cycle that involves a parasitic phase in which they feed on the blood and bodily fluids of large piscivorous fishes. Following the invasion of the Great Lakes by sea lampreys in the early 20^th century, sea lamprey parasitism contributed to major declines in the populations of commercial and sports fisheries in that basin. The lampricide 3-trifluoromethyl-4-nitrophenol (TFM), developed in the late 1950s,is now routinely applied to tributaries of the Great Lakes to control sea lamprey populations. This lampricide is selectively toxic to larval sea lampreys, which typically reside as …

The Effects Of Exercise Intensity On Acylated Ghrelin, Active Glucagon-Like Peptide-1, And Appetite: Examining The Potential Involvement Of Interleukin-6, Hashim Islam

Theses and Dissertations (Comprehensive)

Interleukin-6 (IL-6) stimulates the release of appetite-regulating hormones in animals and associates with decreased energy intake in humans. Thus, IL-6 may contribute to the intensity- dependent effects of exercise on appetite-related parameters. The purpose of this study was to examine the effects of exercise intensity on IL-6, appetite-regulating hormones, and appetite perceptions. Eight active young males completed four sessions: 1) Moderate-intensity continuous training (MICT; 30 min running, 65% VO2max); 2) High-intensity continuous training (HICT; 30 min running, 85% VO2max); 3) Sprint interval training (SIT; 4 x 30 sec “all-out” running bouts separated by 4 min recovery); 4) Control (CTRL; no …

Scalar Short-Term Memory, Tyler D. Bancroft

Theses and Dissertations (Comprehensive)

The location of the brain’s working and short-term memory (WM/STM) “system” is unclear. The existence of a dedicated WM/STM system is itself under debate. Recently, it has been proposed that WM/STM storage relies not on a dedicated system in prefrontal cortex, but rather that it is an emergent function of interaction between attentional and representational systems (e.g., sensory cortex) in the brain. However, mnemonic representations of very simple stimuli have repeatedly been shown to exist in frontal cortex. In this manuscript, I use computational and behavioural methods to demonstrate similarities between the representations of different types of very simple stimuli …

A Biophysical Study Of The Ion Transport Mechanism In Uncoupling Protein 2 By Investigating The Role Of Lysine Residues In Its Matrix Network, Stephanie O. Uwumarenogie

Theses and Dissertations (Comprehensive)

ABSTRACT

Uncoupling protein 2 (UCP2) is one of five UCP homologues found in the inner mitochondrial membrane that transports protons from the intermembrane space to the mitochondrial matrix. In turn, the proton motive force is dissipated and less ATP is produced in the mitochondria. UCP2 is proposed to influence insulin secretion in type II diabetes, and decrease the amount of reactive oxygen species produced in the mitochondria, however the detailed mechanism of ion (proton and anions) transport in UCP2 and other UCP homologues are not fully understood. Sequence alignment analysis performed on proteins in the mitochondrial carrier family (MCF) including …

Seasonal Evolution Of Active Layer Formation In Subarctic Peat Plateaux And Implications For Dissolved Organic Matter Composition And Transfer, Jennifer L. Hickman

Theses and Dissertations (Comprehensive)

Peat-accumulating wetlands are ecosystems whose rate of photosynthetic production of organic matter is greater than that of its decomposition, resulting in a build up of soil organic matter that may take centuries to fully decompose. Carbon (C) stocks within these ecosystems are a function of inputs from photosynthesis, and losses from heterotrophic decomposition. Due to the short growing season and overall cold climate of boreal and tundra regions, C has been accumulating within these landscapes, mostly in soil organic matter, since the last glaciation. Climate change, predicted to result in rising temperatures and increased precipitation, has begun to degrade the …

The Contribution Of The Cerebello-Thalamo-Cortical Circuit To The Pathology Of Non-Dopaminergic Responsive Parkinson's Disease Symptoms, Shannon C. Lefaivre

Theses and Dissertations (Comprehensive)

It has been well established that motor symptoms in Parkinson’s disease (PD) are primarily associated with dopaminergic degeneration in the basal ganglia. However, symptoms which respond poorly to dopaminergic replacement, such as tremor, gait, and balance deficits, point to an alternative pathology to dysfunction of the basal ganglia. Over-activity of the cerebellum has been demonstrated in PD, however it is not entirely clear how the cerebellum might be affecting motor symptoms. A lack of consensus exists regarding how cerebellar over-activity might be influencing PD tremor, and whether resting and postural tremor are differentially influenced by cerebellar dysfunction. It is also …

The Role Of Oxidative Stress In The Mechanisms Of Ammonia-Induced Brain Swelling And Tolerance In The Goldfish (Carassius Auratus), David F. Jones Lisser Mr.

Theses and Dissertations (Comprehensive)

Toxic build-ups of ammonia can cause potentially fatal brain swelling in mammals, but such swelling is reversible in the anoxia- and ammonia-tolerant goldfish (Carassius auratus). The mechanisms of ammonia-induced brain swelling and tolerance remain elusive, but several studies have suggested a role for reactive oxygen species (ROS), which may damage proteins and lipids in the plasma membrane of astrocytes in the brain. As a result, osmotic gradients across cell membranes may be altered leading to water uptake by astrocytes and swelling. While a role for ROS has been proposed in mammals, no studies have addressed this question in …

Spanish River Carbonatite: Its Benefits And Potential Use As A Soil Supplement In Agriculture, James J

Theses and Dissertations (Comprehensive)

A critical problem facing agriculture today is being able to consistently and sustainably provide plants with adequate nutrients for growth. With this problem being exacerbated by the ever-increasing human population, new perspectives and techniques are required to ensure global food security. In order to fully realize potential solutions, however, plant growth and nutrition cannot be exclusively focused upon. The soil-microorganism-plant system is comprised of many interconnected and interdependent processes that together support plant growth: it is upon these processes that the focus must be placed. In this work, the agromineral Spanish River Carbonatite (SRC) is characterized using the framework of …

Nickel And Copper Mixture Toxicity To Daphnia In Soft Water, Prachi Deshpande

Theses and Dissertations (Comprehensive)

Industrially important metals, such as Cu and Ni, sometimes are present at elevated concentrations in lakes, including those in the Sudbury, ON region. Although they are essential metals, their divalent-cation state (Cu²⁺ and Ni²⁺) can be toxic at high concentrations in the water. The free-ion toxicity of each of these metals has been studied in isolation, but rarely as a mixture. The economic importance of Cu²⁺ and Ni²⁺ makes them essential to study in the context of mixture toxicity. The objectives were to: (1) determine Cu and Ni mixture toxicity to Daphnia through acute LC50 …

Multi-Criteria Decision Analysis (Mcda) For Agricultural Sustainability Assessment, Byomkesh Talukder

Theses and Dissertations (Comprehensive)

Multi Attribute Utility Theory (MAUT), Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE) and Elimination methods of Multi-Criteria Decision analysis (MCDA) are tested to assess and compare the sustainability of different agricultural systems. Indicators and composite indicators are derived from data gathered using the agricultural sustainability categories of Productivity, Stability, Efficiency, Durability, Compatibility and Equity (PSEDCE).

Agricultural systems around the world face challenges from current agricultural practices, over-exploitation of natural resources, population growth and climate change. As a result, understanding agricultural sustainability has become a global issue. Assessment is a first step in benchmarking and tracking agricultural sustainability and …

The Sublethal Physiological Effects Of Exposure To Copper And Silver Mixtures On Rainbow Trout (Oncorhynchus Mykiss), Wesley Truong

Theses and Dissertations (Comprehensive)

The mechanisms behind metal-metal interactions in freshwater environments are currently not well understood. Freshwater environments consist of many different types of metals, from those naturally present such as copper (Cu) and those that originate from anthropogenic sources like silver (Ag). Both Cu and Ag use apical sodium (Na⁺) channels for uptake into the gills of freshwater fish. In the gills, the mechanisms of Cu²⁺ and Ag⁺ toxicity appear to be similar to one another, which is by inhibiting Na⁺ /potassium (K⁺)- adenosine triphosphatase (NKA) and carbonic anhydrase (CA). Inhibition of NKA and CA …

Implications Of Galling Herbivory On Ground Thaw In Canada’S Northern Boreal Forest, Allison Mcmanus

Theses and Dissertations (Comprehensive)

Canada’s northern boreal forest has faced significant climate warming over the past century. This change can have direct and indirect effects on forest dynamics, including altering the disturbance patterns of herbivores and changing the abundance of natural enemies. Warmer air temperatures can impact the distribution and survival of arthropods, both novel species and resident natural enemies. Gall-inducing mites are a resident natural enemy in high latitude forests and have been shown to drive dramatic reductions in gas-exchange rates in infested plants. Physiological reductions in plants can directly affect the shrub energy balance and underlying soil processes. This can have major …

The Bigger Picture: Piecing Together The Experiences Of Family Members Living With High-Functioning Children With Autism Spectrum Disorder, Lauren Thomson

Theses and Dissertations (Comprehensive)

The purpose of this research was to explore the experiences of family members living with a child with ASD. The specific research questions that were addressed included: 1. How is a family member affected by having a child with ASD in the family unit; and 2. How does living with a child with ASD affect family functioning? The theoretical orientation of phenomenology was used to guide this research and to allow the “voice” of family members of children with ASD to be heard. The purpose of phenomenology is to distill individuals’ experiences with a phenomenon down to an “essence” of …

What Lies Past Remission: The Perceived Late Effects Of Pediatric Cancer, Monica L. Molinaro

Theses and Dissertations (Comprehensive)

Objective

Pediatric cancer survival rates are increasing (Childhood Cancer Canada Foundation, 2011) and with this, so are the late effects of pediatric cancer (Oeffinger et al., 2006). This research examines the lived experiences of the perceived long-term effects of pediatric cancer on adult survivors and their primary support persons in order to understand the multifaceted nature of the illness on adults, and how it affects others close to them.

Methods

The theoretical orientation used to guide the research was phenomenology in order to present an accurate depiction of all the participants’ lived experiences. Specifically, background questionnaires were administered and one-on-one …