ETDs: Doctoral Theses

Permanent URI for this collectionhttps://laurentian.scholaris.ca/handle/10219/480

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Adaptation during a longitudinal integrated clerkship: the lived experiences of third-year medical students at the Northern Ontario School of Medicine.
(Laurentian University of Sudbury, 2013-07-31) Dubé, Tim V.
There are three interrelated concepts of what medical students learn, which include the formal, informal, and hidden curriculum. Several researchers who have investigated notions of the hidden curriculum have demonstrated how the experiences of medical training entrenched in the hidden curriculum can have a profound impact on medical student adaptation. The most influential transitional stage in undergraduate medical education is the third-year clinical clerkship, when medical students transition from classroom learners into clinicians. The Northern Ontario School of Medicine’s (NOSM) clinical clerkship year consists of a mandatory eightmonths of living and working in rural and northern communities throughout Northern Ontario, and learning in the context of rural family practice. Informed by a social constructivist research paradigm, I explored how 12 third-year students described the challenges they had to manage and, in response, the strategies they employed to adapt to their clerkship. I elicited their experiences and perspectives to contribute to a rich understanding of how students at the NOSM describe developing processes of adaptation during the Comprehensive Community Clerkship. Data were collected between August 2011 and April 2012, including: a) pre-clerkship interviews and a demographic questionnaire, b) mobile methods in the form of ‘guided walks’ in the communities, and c) post-clerkship interviews. The quality of the data collection and analysis were enhanced through processes of methodological and interpretive rigour, representativeness and authenticity, rich description and contextual relevance, audit trail, and reflexivity. Through an inductive thematic analysis of the data, the findings provide a rich description of events experienced such as medical training in one’s hometown or a familiar community, iv transitions including adaptation to the clinical setting and to the medical profession, and the influence of the clerkship on career path, personal well-being, and empathy for patients. The findings serve to advance our understanding of how medical students describe developing processes of adaptation throughout a longitudinal integrated clerkship. Implications are considered for medical students, the NOSM, the clerkship communities, and medical schools nationally and internationally. I propose recommendations regarding the suitability of authentic methods in medical education research, and discuss the implications for rural and northern health research.
Adaptation of microalgae bioprospected from stressed environments in Northern Ontario for the production of lipids
(2020-12-16) Desjardins, Sabrina Marie
Photosynthetic green microalgae are a promising bio-feedstock that can be used to generate lipids for transesterification into biodiesel and/or various human health products such as polyunsaturated fatty acids. Unfortunately, due to their cultivation requirements, such as high energy requirements and carbon dioxide (CO2) as a carbon source, large-scale biomass production generally remains uneconomical. To address this issue, the use of industrial flue gas as a low-cost source of CO2 and a biorefinery approach to help mend the economic burden of microalgae-based products with an emphasis on creating co-products from lipid-extracted biomass (LEB) are assessed in this thesis. Microalgae’s ability to sequester CO2 through photosynthesis is also advantageous in mitigating harmful industrial emissions. While these flue gases can have high concentrations of CO2, they also can contain numerous contaminants (e.g., heavy metals, particulate matter) that discourage microalgae growth, and therefore their ability to fix CO2. But, the most significant issue can be high nitrous oxide (NOx) and sulphuric dioxide (SO2) concentrations within a flue gas that cause acidification when bubbled through liquid media. It is due to this acidification that finding the productive microalgae species to grow in those systems can be problematic. To address this, bioprospecting acid-tolerant microalgae from low pH environments in active and non-active mining sites was explored and the acidophilic species present identified through DNA sequence analysis. Bioprospected algal species were then grown in acidic conditions similar to those created by bubbling flue gas from a nickel smelter into water (pH 2.5). From this work, it was found that the acid-tolerant green microalgae in the genus Coccomyxa acclimated to the acidic conditions with suitable growth rates (0.136 day-1) and biomass production (25.71 mg L-1day-1). However, anabolic production of target biochemical molecules, such as lipids, is the key step in the bio-product process. It is known that microalgae have the ability to accumulate bioactive compounds when placed in stressed environments, such as high illumination and low nutrient availability, but little is known an about the impact of low pH and in particular the lipid composition of acidophilic microalgae. Research confirmed that the lipid compositions of bioprospected acid-tolerant microalgae was in the target range (13%). However, further work showed that an increased total lipid content (up to 27%), with a desirable rise in the relative level of health beneficial higher polyunsaturated fatty acid, could be achieved by applying dark stress at the end of the exponential growth phase. It is, therefore, proposed that this approach could be an easy, low-cost method to enhance lipid productivity
Air entrainment and air-water separation in hydraulic air compressors
(2018-08-16) Hutchison, Alex
A hydraulic air compressor (HAC) is an isothermal gas compressor that uses hydropower to compress air, originally developed by Charles Taylor in the 1890s to supply industry with compressed air. In the modern revival of this technology, the hydropower will be provided by pumps rather than natural sources. As such, energy efficiency is an important driver of component design; all of the hydropower is consumed either to overcome irreversibility or to compress air. The compressor relies on the increasing pressure of water flowing downward in a downcomer to compress air in the form of bubbles being dragged along with the flow. The air entrainment process at the top of the downcomer is facilitated by a mixing head. At the bottom of the downcomer, the bubbles are separated from the flow in a separator vessel. The objective of this thesis is to develop the design methodology for the air entrainment and air-water separation components on either end of the downcomer process. Several mixing heads were tested on a small (4.5 m height) prototype HAC. The test without a mixing head successfully entrained air, confirming that air entrainment is a system effect. Two heads with dissimilar geometry were associated with the lowest irreversibility, leading to the conclusion that the best design at that scale is a mixing head incorporating some form of vortex breaker. Air entrainment is driven by a system energy balance and not exclusively by a local Venturi geometry. The fraction of the air successfully captured in the plenum of the separator is called the separator effectiveness. Mechanistic models have been created to characterize both the irreversibility and separator effectiveness of two types of gravity separator (horizontal and vertical orientation) for iv the design of separators for future commercial-scale compressors. The separator effectiveness models require as input the flow field information from computational fluid dynamics analysis and the bubble size distribution at inlet. The bubble size distribution was measured on the small prototype and used to select a bubble size prediction model for testing on a much larger scale (29 m height) demonstrator HAC. The displacement model for horizontal separators matched the actual performance at the prototype scale well, particularly at high flow rate. The vertical velocity model produced a good match for the separator on the demonstrator HAC, but not for the same bubble size model identified on the small prototype.
Antibacterial activity of freshwater green microalgae isolated from water bodies near abandoned mine sites in Ontario, Canada
(2018-07-06) Senhorinho, Gerusa Neyla Andrade
Progress of modern medicine relies on the discovery of new antibiotics. The increasing threat of antibiotic resistant bacteria, leading to an increase in morbidity and mortality of patients previously considered low risk, has highlighted the serious need for the expansion of antibiotic research and development. Historically, natural products have been the most successful source of antibiotics as they have complex and unique chemical structures and modes of action. Since most available antibiotics are originally a result of the secondary metabolism of bacteria and fungi, microorganisms from diverse environments capable of producing secondary metabolites have been and currently are being investigated for antibacterial production. Green microalgae are eukaryotic microorganisms that can be found in a very wide range of habitats, including extreme environments. These microorganisms are known to produce a series of commercially valuable compounds as a result of their secondary metabolism. The central aim of this thesis was to determine the potential of green microalgae as antibiotic producers collected (bioprospected) from water bodies near abandoned mine sites in Ontario, Canada. These water bodies exhibited a variety of chemical profiles, including high metal concentrations and low pH. Forty species of green microalgae were subsequently isolated and their extracts tested against various bacteria. The findings showed that 37.5% of these microalgae produced antibacterial compounds that seem to specifically inhibit the growth of Gram-positive bacteria, in particular the opportunistic pathogen Staphylococcus aureus. This was a higher success rate than any previous study on green microalgae. In addition, the evaluation of crude extracts of Chlamydomonas sp., the most common isolated species, demonstrated variation in antibacterial activity during cell growth. The highest antibacterial activity from this species was found in the exponential phase. Furthermore, green microalgal extracts exhibiting antibacterial activity also decreased the cell viability of malignant cells, particularly the rapidly dividing human ovarian carcinoma A2780 cells. However, the extracts did not decrease the cell viability of non-malignant cells. Taken together, the results of this thesis reveal that freshwater green microalgae from water bodies near abandoned mine sites are potential sources of antibacterial compounds against Grampositive bacteria and should be further investigated against rapidly dividing malignant cells.
Application of neuroergonomics in the industrial design of mining equipment.
(2015-06-26) Mach, Quoc Hao
Neuroergonomics is an interdisciplinary field merging neuroscience and ergonomics to optimize performance. In order to design an optimal user interface, we must understand the cognitive processing involved. Traditional methodology incorporates self-assessment from the user. This dissertation examines the use of neurophysiological techniques in quantifying the cognitive processing involved in allocating cognitive resources. Attentional resources, cognitive processing, memory and visual scanning are examined to test the ecological validity of theoretical laboratory settings and how they translate to real life settings. By incorporating a non-invasive measurement technique, such as the quantitative electroencephalogram (QEEG), we are able to examine connectivity patterns in the brain during operation and discern whether or not a user has obtained expert status. Understanding the activation patterns during each phase of design will allow us to gauge whether our design has balanced the cognitive requirements of the user.
Application of physical properties measurements to lithological prediction and constrained inversion of potential field data, Victoria Property, Sudbury, Canada.
(2015-11-30) Mahmoodi, Omid
In recent years the number of near-surface deposits has decreased significantly; consequently, exploration companies are transitioning from surface-based exploration to subsurface exploration. Geophysical methods are an important tool to explore below the surface. The physical property data are numerical data derived from geophysical measurements that can be analyzed to extract patterns to illustrate how these measurements vary in different geological units. Having knowledge of links between physical properties and geology is potentially useful to obtain more precise understanding of subsurface geology. Firstly, down-hole density, gamma radioactivity, and magnetic susceptibility measurements in five drillholes at the Victoria property, Sudbury, Ontario were analyzed to identify a meaningful pattern of variations in physical property measurements. The measurements grouped into distinct clusters identified by the fuzzy k-means algorithm, which are termed ‘physical log units’. There was a meaningful spatial and statistical correlation between these physical log units and lithological units (or groups of lithological units), as classified by the geologist. The existence of these relationships suggests that it might be possible to train a classifier to produce an inferred function quantifying this link, which can be used to predict lithological units and physical units based on physical property data. A neural network was trained from the lithological information from one hole, and was applied on a new hole with 64% of the rock types being correctly classified when compared with those logged by geologists. This misclassification can occur as a result of overlap between physical properties of rock types. However, the predictive accuracy in the training process rose to 95% when the network was trained to classify the physical log units (which group together the units with overlapping properties). Secondly, lithological prediction based on down-hole physical property measurements was extended from the borehole to three-dimensional space at the Victoria property. Density and magnetic susceptibility models were produced by geologically constrained inversion of gravity and magnetic field data, and a neural network was trained to predict lithological units from the two physical properties measured in seven holes. Then, the trained network was applied on the 3D distribution of the two physical properties derived from the inversion models to produce a 3D litho-prediction model. The lithologies used were simplified to remove potential ambiguities due to overlap of physical properties. The 3D model obtained was consistent with the geophysical data and resulted in a more holistic understanding of the subsurface lithology. Finally, to extract more information from geophysical logs, the density and gamma-ray response logs were analyzed to detect boundaries between lithological units. A derivative method was successfully applied on the down-hole logs, and picked the boundaries between rock types identified by geologists as well as additional information describing variation of physical properties within and between layers not identified by the geologist.
Assessing the origin of some representative Archean-Paleoproterozoic porphyry Cu ± Au deposits
(2021-06-04) Meng, Xuyang
Most known porphyry Cu ± Au deposits are exclusively associated with oxidized and sulfurrich Phanerozoic arc-related magmas, but Precambrian analogues are rare. The genesis of some rare examples of such deposits (e.g., Tongkuangyu in Trans-North China Orogen) remains debated, and in particular, it remains unclear as to whether similar metallogenic processes that typify the Phanerozoic deposits also operated in the Precambrian. To resolve these issues, three study areas were chosen to variably characterize relevant aspects of these deposits in the context of porphyry-type metallogenies (i.e., the nature of mineralization, the redox states and volatile element abundances of the causative magmas): (1) the ~2.1 Ga Tongkuangyu deposit in Trans-North China Craton; (2) the ~1.88 Ga Haib porphyry Cu deposit, Southern Namibia; and (3) representative porphyry-type Cu ± Au deposits (Côté Gold, St-Jude, and Croxall) in the ~2.7 Ga Abitibi subprovince. At the Tongkuangyu deposit, remapping of the distribution of the host rocks, alteration, and mineralization support a porphyry-type model where ore formation occurred at ~2.1 Ga. This age is significantly later than the host granodiorite porphyry (~2.18 Ga) and schists (~2.5–2.2 Ga) and indicates that porphyry-type mineralization need not be linked directly to a causative magma exposed at surface. Instead, the latter is interpreted to be represented by subjacent porphyritic stocks and dikes. At the Haib deposit, the host calc-alkaline plutonic rocks and mineralization are dated to ca. 1886–1881 Ma. Estimations of magmatic fO2 and S, based on zircon geochemistry, apatite µXANES spectra, and apatite S analysis, demonstrate that oxidized, sulfur-rich arc magmas associated with porphyry Cu mineralization already existed in the late Paleoproterozoic. In addition, zircon Hf-O isotopes and whole-rock geochemistry support magmas of mantlederivation with minor crustal contributions that experienced amphibole ± plagioclase fractionation. These features of the Haib magmas are thus similar to those for Phanerozoic porphyry Cu deposits. For the ~2.7 Ga TTG (tonalite-trondhjemite-granodiorite-diorite)-related porphyry-type Cu ± Au deposits in the Abitibi subprovince, whole-rock geochemistry, zircon Hf-O isotopes, apatite S contents, and multiple oxybarometers suggest that variable magmatic origin and fO2 for the causative magmas. The rarity of porphyry-type Cu-Au deposits in these older settings may be attributed to either location restriction of these favorable metallogenic conditions and/or preservation, or exploration bias.
Auditor professional skepticism – a cross-cultural study in the global International Financial Reporting Standards environment: the case of Canada and Brazil
(2020-03-19) McGillis, Sheila
The global financial reporting environment is undergoing significant change, with a global trend toward more countries adopting the International Financial Reporting Standards for public companies. Concerns exist as to potential barriers to harmonization, such as culture; therefore, it is important to draw on institutional mechanisms, such as auditing, to encourage compliance and harmonization. With this, there is a need to better understand the factors affecting the quality of such audits. Auditors’ professional skepticism is a key factor in ensuring audit quality. This exploratory quantitative study explores an area that is not well researched: specifically, the cross-cultural professional skepticism of auditors. Through a correlational design, the study provides insights as to whether auditors from different cultures make different skeptical judgments and decisions. This study also investigates whether prior research linking skeptical traits to increased professional skepticism in auditors is exportable from one culture to another. The major finding of this study is that there is no significant difference in the professionally skeptical judgments and decisions of entry-level auditors from Canada and Brazil. Culture is not associated with the professional skepticism of these auditors. The study also highlights that skepticism, as a trait does not correlate with professional skepticism of auditors across all cultures, specifically in Canada and Brazil. This study fills a major void in the literature concerning the study of cross-cultural professional skepticism and it extends prior research regarding the associations between skepticism as a trait and auditors’ professional skepticism by investigating auditors from two very different cultures. This study provides insights that are relevant to practitioners such as regulators, auditors and auditing firms, as well as academics in auditing, accounting, psychology and cultural studies.
Background reduction techniques and simulations for the PICASSO and PICO dark matter search experiments.
(2019-11-18) Scallon, Olivia
Dark matter is one of the most challenging mysteries of cosmology. The detection of Dark Matter is a main objective in modern experimental physics. The PICASSO and then the PICO experiments work towards the direct detection of WIMPs (Weakly Interacting Massive Particles) with superheated liquid detectors. Phase transitions in the superheated liquids are triggered by the nuclear recoil caused by the elastic collision of a dark matter particle. The phase transition in the detectors leads to the formation of a gaseous bubble. The acoustic signal of the nucleation of a bubble is recorded with piezoelectric sensors and pictures of the bubbles are taken with cameras. Many techniques are used to isolate potential dark matter signal from background signals. This thesis presents the work done for the fabrication process and purification techniques of the PICASSO detectors in the clean room at Université de Montréal. The detectors built with these new purification techniques allowed a background reduction of a factor of 10. The techniques and methods will be presented as well as the latest results from the data taken with these detectors. Simulations for the PICO experiment will also be presented. MCNP neutron background simulations from radioactive materials in the PICO detector will be presented. MCNP simulations for neutrons in the SNOLAB drift will also be presented as well as other MCNP simulations for the design and optimisation of the experiment. Finally, Geant4 muon-induced neutron simulations in the SNOLAB drift will be presented as well as Geant4 simulations for the design of a muon veto. These simulations were built entirely from scratch by using the SHIELDING physics list.
Baking power: French-Canadian and Franco-Ontarian cultural identity as defined by evolving traditional foodways in Astorville, Ontario
(2017-04-10) Weiskopf-Ball, Emily
Questions about cultural identity and allegiance are complicated. What makes a person French, French-Canadian or Franco-Ontarian? What is the difference between these various labels? How do demographics, gender, and age impact the ways in which cultural allegiance is created, maintained, or discarded? What defines a person’s membership in a cultural group? Is it one’s ability to speak the language? To make and/or eat cultural foods? If one of these fails to be present, can the person still be a part of the group? In our multicultural country, and especially in rural communities in Northern Ontario where Francophones find themselves to be part of a minority, such questions do not have simple answers. Studying cultural retention in such communities necessitates paying attention to more than just who is speaking French and/or to who is an activist for French rights. It also requires understanding how individual attitudes and behaviours are like and/or unlike those of others and of the larger group. Foodways are one of the specific cultural practices that can tell us about the group. Indeed, traditional foods have been shown to be very political expressions of personal values and opinions. What power does French-Canadian food have over those who make it? What does it tell us about those who claim allegiance to this cultural group? This interdisciplinary case study of Astorville, Ontario, relates to the fields of food studies, cultural studies, history, gender studies, material culture studies, performance studies, and autoethnography. By studying foodways, which are closely connected to heritage, language, religious practices, and rituals, this project seeks to understand how minority groups resist and/or acquiesce to societal pressures to conform to the culture of the majority. Knowing that modernisation and urbanisation have changed the lifestyle of once agricultural communities, that women now participate in the workforce, and that an individual’s personal history is an important factor in determining how one subscribes to cultural norms, this is an important time to understand the cultural evolution taking place in communities, like Astorville, Ontario, where the French population has gone from a majority to a minority since it was established.
Biochemical adaptations in pseudomonas fluorescens exposed to nitric oxide, an endogenous antibacterial agent
(Laurentian University of Sudbury, 2014-05-21) Auger, Christopher
Nitric oxide (NO), a free radical released by macrophages (a subset of white blood cells) as a response to infection, is noxious to organisms due to its ability to disable crucial biomolecules such as lipids, proteins and DNA. Although normally effective at eradicating invading bacteria, several pathogens have developed mechanisms to detoxify NO and its toxic by-products, reactive nitrogen species (RNS). While some of these detoxification processes have been characterized, very little is known about the metabolic changes that enable microbes to survive this deleterious environment. Investigations into the effects of RNS on microbial physiology have shown that these harmful radicals inactivate the citric acid cycle and oxidative phosphorylation, the series of reactions responsible for making energy aerobically. The central aim of this thesis was to determine how the organism counteracts the detrimental effects of RNS, while bypassing the ineffective central metabolic pathways. The findings presented herein show that P. fluorescens engineers an elaborate metabolic network to generate ATP whilst withstanding the injurious effects of nitrosative stress. Crucial to this adaptation is the ability to produce energy via substrate level phosphorylation, a necessity that arises out of the cells’ inability to produce a substantial amount of ATP using the electron transport chain (ETC). The up-regulation of the enzymes citrate lyase (CL), phosphoenolpyruvate carboxylase (PEPC) and pyruvate, phosphate dikinase (PPDK) helps the organism accomplish this feat. Blue native polyacrylamide gel electrophoresis (BN-PAGE), high performance liquid chromatography (HPLC) as well as co-immunoprecipitation (CO-IP) studies were applied to demonstrate that these proteins form a metabolon, a transient complex of enzymes that ensures citrate is converted into its desired end products, pyruvate and ATP. In order to gauge the individual contributions iv of phosphoenolpyruvate-dependent kinases, a novel in-gel activity assay was developed to probe these enzymes under disparate conditions. These results suggest that the organism switches from an ATP-dependent metabolism to one based on the utilization of pyrophosphate (PPi). The rationale for this appears to be energy efficiency, as pyrophosphate-dependent glycolysis can theoretically produce five ATP rather than the two yielded by Embden-Meyerhof glycolysis. Additionally, the up-regulation in activity of the enzymes adenylate kinase, nucleoside diphosphate kinase and acetate kinase seem to ensure that ATP generated by PPDK is properly shuttled and stored when aerobic metabolism is defective. The lower activity of inorganic pyrophosphatase likely ensures an adequate supply of pyrophosphate for the activity of PPDK. Taken together, this research reveals the critical role metabolism plays in the survival of microbes under the onslaught of NO and RNS. As several of these enzymes are absent in mammalian systems, they present themselves as novel targets for the development of new antibacterial agents. A comprehensive awareness of bacterial defense systems in response to NO may lay the groundwork to developing more effective treatments to impede microbial infections.
Biochemical and molecular characterization of microbial communities from a metal contaminated and reclaimed region.
(2017-04-18) Narendrula, Ramya
Metal contamination in the Greater Sudbury Region (GSR) resulted in severe environmental degradation. Soil liming and tree planting have been the main approaches to restoring the damaged ecosystem. The specific objective of the present study was to assess the effects of soil metal contamination and liming on 1) microbial biomass and abundance, 2) bacterial and fungal diversity, and 3) enzymatic activities and soil respiration. Phospholipid fatty acid (PLFA) analysis and 454 pyrosequencing were used to address these research objectives. Total biomasses for bacteria, arbuscular fungi (AM fungi), other fungi and eukaryotes were significantly lower in metal contaminated compared to uncontaminated reference areas. Analysis of bacterial communities revealed Chao1 index values of 232 and 273 for metal contaminated and reference soils, respectively. For fungi, the Chao index values were 23 for metal contaminated and 45 for reference sites. There was a significant increase of total microbial biomass in limed sites (342.15 ng/g) compared to unlimed areas (149.89 ng/g). Chao1 estimates followed the same trend. But the total number of OTUs (Operational Taxonomic Units) in limed (463 OTUs) and unlimed (473 OTUs) soil samples for bacteria were similar. For fungi, OTUs were 96 and 81 for limed and unlimed soil samples, respectively. Bacterial and fungal groups that were specific to either limed or unlimed sites were identified. Bradyrhizobiaceae family with 12 genera including the nitrogen fixing Bradirhizobium genus was more abundant in limed sites compared to unlimed areas. For fungi, Ascomycota was the most predominant phylum in unlimed soils (46.00%) while Basidiomycota phylum represented 85.74% of all fungi in the limed areas. Detailed analysis of the data showed that although soil liming increases significantly the amount of microbial biomass, the level of species diversity remained statistically unchanged. Soil respiration rates were higher in limed soils (65 ppm) compared to unlimed soils (35 ppm). They were significantly lower in metal contaminated sites (55 ppm) compared to reference sites (90 ppm). β-glucosidase (BG), cellobiohydrolase (CBH), β-N-acetylglucosaminidase (NAGase), aryl sulfatase (AS), acid phosphatase (AP), alkaline phosphatase (AlP), glycine aminopeptidase (GAP), and leucine aminopeptidase (LAP) activites were significantly higher in limed compared to unlimed sites. Metal contamination significantly reduced the activities of these enzymes with the exception of LAP. An opposite trend was observed for peroxidase (PER) enzyme activity that was higher in unlimed and metal contaminated sites compared to limed and reference areas.
Biogeochemistry of wetlands in watersheds affected by aerial deposition of metals, and linkages to aquatic ecosystem recovery.
(Laurentian University of Sudbury, 2014-10-22) Szkokan-Emilson, Erik John
Wetlands are prevalent in the boreal shield, and are efficient at retaining metals and thus modifying the chemistry of downstream receiving waters. The Sudbury region of Ontario, Canada has suffered over a century of elevated metal and sulphur deposition from mining and smelting activity, and wetlands in the area have provided an important ecosystem service by adsorbing large concentrations of metals over decades of emissions. However, metals can be released from peat in some circumstances such as during dry periods that result in a drop in water table height. With emissions declines in the region, there is the potential that wetlands have remained contaminated and are now acting as a source of metals at annual scales. Stream metal concentrations and dissolved organic matter (DOM) exports were evaluated in six Sudbury wetland-draining streams to address the question: Are wetlands in mining-impacted watersheds releasing potentially toxic metals to receiving waters? Water table declines occured in response to summer droughts, and some metals (Al, Co, Cu, Fe, Mn, Ni, and Zn) were released during rewetting events. Other metals that have a high affinity for DOM (Cu, Al, Fe) were also released from some wetlands in the summer in response to mineralization and DOM release. Concentrations in streams exceeded provincial guidelines and fluxes of some metals (e.g. Ni, Co) exceeded atmospheric deposition inputs to lakes by as much as 12 times. Changes in DOM concentration and composition occurred concurrently with the mobilization of metals after drought, with large decreases in aromaticity (SAC340) coupled with decreased DOC concentration. Biotic ligand modelling indicated that these drought-related DOM changes had a large effect on Cu toxicity, and while predicted Ni toxicity increased because of drought-related increases in Ni concentrations, predicted Cu toxicity increased primarily because of drought-related DOM changes. It is likely that these metal stores will take a very long time to deplete, iv and this offers important insight into the recovery trajectory of aquatic communities in watersheds affected by smelting. The results can be used to advance restoration efforts in the Sudbury region and other similar smelter-impacted areas affected by aerial depositon of metals.
Biometeorology: review and analysis with regard to traumatic brain Injury acquisition in professional football, as well as traditional and digital economic markets
(2019-07-09) Juden-Kelly, Lyndon
This research explores Biometeorology, which is the relationship between the environment and human behavior. Previous research has indicated that meteorological events such as lunar cycles, solar activity, temperature, and humidity have been extensively documented to affect human psychophysiology through systemic variation. The purpose of this document is to explore the effects of environmental factors on typical everyday aggregate behaviors in distinct, unique and separate investigations that relate to participation in sporting events and economic activities in order to determine if these naturally occurring influences are genuine. For example, local weather related and extra-terrestrial phenomena were collected during timestamped Traumatic Brain Injury (TBI) acquisition in the National Football league (NFL) for 645 concussed players from 2012-2015. Components of the Earth’s geomagnetic field were also documented in relation to global search tendencies for highly emotional states in addition to stock market indices. Furthermore, solar and lunar cycles were recorded during the monumental rise in the cryptocurrency market in order to identify if these cyclical background patterns systemically altered interest in Bitcoin (BTC) and Ethereum (ETH) or influenced their price index in-and-of-itself. The results indicate that intrinsic capacities of the game of football inherently impacted injury severity and return to play considerations. TBI’s did however, vary as a function of geo-coordination and were most pronounced in the Northwest U.S. Injury severity was also found to be greatest during increased geomagnetic intensities. Lunar contributions also appeared to play a central role in injury acquisition insofar as TBI player height weight and injury severity were predicted by solar and geomagnetic variables of interest during the full moon. Aggregate search behavior on the Internet of Things (IoT) was found to correlate with magnetic variability, geomagnetic intensity as well as Dow Jones price movement and trading volume. Finally, traditional technical analysis indicators closely followed cryptocurrency price. However, Bitcoins Aroon up and down was found to cycle with the Moon, while Ethereum’s Heiken Ashi displayed a relationship with the Sun. Internet interest in Ethereum was found to have significant associations with the Earth’s geomagnetic field, the Sun and the Moon which was enhanced during specific alignments of these heavenly bodies. In summary, seemingly random events and aggregate group behaviors are intimately associated with external interconnected dynamics.
The black sun of boredom: Henri Lefebvre and the critique of everyday life
(Laurentian University of Sudbury, 2013-07-31) Gamsby, Patrick
This dissertation examines how boredom can be understood in the context of Henri Lefebvre’s (1901-1991) critique of everyday life. Through an integration of the boredom literature, both the fully developed studies as well as fragmentary passages, I argue that Lefebvre’s critique of everyday life adds an important dimension to understanding boredom in modernity. One of the leading strands in boredom studies today argues that boredom is an historically specific experience unique to the rhythms of life imparted with the onset of modernity. Viewed in this light, boredom is a relatively recent phenomenon that can be linked to what Lefebvre calls the ‘double process’ of industrialization and urbanization. Although the mass profusion of boredom has left a seemingly indelible mark on society, it has received relatively little attention in both everyday life and academia. First coined in the middle of the 19th century, boredom is a relatively new word for what today is an all too pervasive experience. Writing throughout most of the 20th century, Lefebvre makes numerous references to boredom, yet, despite claiming that a study of boredom would be a significant contribution to his critique of everyday life, he never developed an in-depth and sustained analysis of this experience. Lefebvre did, however, identify an internal dialectic of mass culture as being an integral component for understanding boredom. It is argued that Lefebvre’s theory of a dialectical process inherent to mass culture is a key for understanding boredom as an historically specific phenomenon. In organizing this dissertation, a constellation of themes are presented in order to articulate this dialectic. After exploring boredom’s relationship to modernity, I then discuss what Lefebvre considers as the verso of modernity, everyday life. Following this, I consider the contradictions of space that give rise to boredom in urban centres and suburban peripheries by critically analyzing both the production of those spaces as well as how they are consumed in everyday life. Finally, I consider the escape from boredom offered in select sounds and images of the culture industry and its opposite, the embrace of boredom in certain 20th century avant-garde art movements. Through a reading of Lefebvre’s critique of everyday life and complementary texts, this interdisciplinary dissertation is a contribution to understanding the mass phenomenon of boredom in modernity.
Cancer cell behaviour in response to chemotherapeutics - a study of docetaxel induced inflammatory cytokine production and the effect of lipopolysaccharides
(2018-05-17) Edwardson, Derek William
The study of cancer is an ever‐evolving discipline and since the 1950's it has been driven by fundamental scientific research using cultured human tumour cell lines isolated from human cancer patients. Over the years it has become evident that patients with cancer of the breast, ovaries, and several other tissues, often respond well to initial chemotherapy treatment, only to be left with tumours that have become resistant to the cytotoxic effects of chemotherapy. This has prompted decades of cellular and mouse‐based studies to characterize the many biomolecular processes by which tumour cells in their microenvironments survive and reproduce in the presence of chemotherapy drugs. This dissertation discusses the role of cytokine production in chemotherapy drug efficacy both in the laboratory and the clinic. Cytokines are naturally released by healthy epithelial, endothelial, and immune cells to convey important messages to other cells and tissues of the body, driving immune responses upon recognition of pathogens or cellular damage. Cytokines have become increasingly considered for their roles in stalling or accelerating cancer progression as well as improving or limiting drug efficacy. In this thesis, we present primary research results that provide novel insight into the mechanism by which chemotherapy drugs induce inflammatory cytokine production and release from human tumour cells. We show that the semi‐synthetic taxane derivative docetaxel, as well as other structurally distinct chemotherapy drugs, induce the release of the inflammatory cytokine TNF‐α from breast and ovarian tumour cell lines. Constitutively increased production and release of TNF‐α and CXCL1 from breast and ovarian tumour cells was also observed upon their selection for survival in increasing concentrations of docetaxel. Docetaxel‐resistant cells were less responsive to acute treatment with docetaxel than their drug‐naive parental cell lines. These cells exhibited increased expression of the plasma membrane‐bound drug‐export protein, P‐glycoprotein, which promotes the efflux of docetaxel and other drugs from tumour cells. Interestingly, restoration of drug into the docetaxel‐ resistant cells not only restored the drugs' cytotoxic effect but also the ability of the cells to respond to drug with increased TNF‐α release. Current paradigms suggest that this response occurs through activation of the pathogen recognition receptor Toll‐like receptor 4 (TLR4), involving direct interaction with docetaxel at the cell surface. This model appears inconsistent with our results showing that cellular drug accumulation is necessary for the response of increased TNF‐α release to occur. We also show that the TLR4 agonist, lipopolysaccharides (LPS), causes increased production of TNF‐ in the presence of docetaxel and increased docetaxel cytotoxicity for both wildtype and docetaxel‐resistant MCF‐7 tumour cells, representing a potential novel strategy to restore chemoresponsiveness in chemoresistant tumours.
Caractéristiques et logiques des musiques populaires
(Laurentian University of Sudbury, 2013-07-31) Lemieux, Suzanne
L’objet de notre thèse de doctorat concerne les caractéristiques et les logiques des musiques populaires. D’une façon générale, nous nous demandons : quelles sont les logiques qui déterminent le thème de l’oeuvre dans la musique populaire ? Quelles caractéristiques découlent de ces logiques ? Les ouvrages recensés ont été classés dans trois ensembles selon que les musiques populaires sont définies comme standard, comme standard et originales ou comme hétérogènes. La thèse veut vérifier laquelle de ces tendances (standard, standard/originale, hétérogène) explique le mieux l’oeuvre de musique populaire. Pour y parvenir, la recherche d’une explication des oeuvres de musique populaire a dû passer par une opérationnalisation et une vérification empirique des oeuvres de musique populaire. Les hypothèses spécifiques liées aux thèses standard, standard/originale et hétérogène, ainsi qu’une hypothèse générale permettant une articulation entre ces trois thèses ont été soumises aux résultats de notre analyse qui a porté sur 110 chansons à succès canadiennes-françaises et françaises qui appartiennent à la période qui va de 1995 à 2005. Les résultats montrent que l’hypothèse des hétérogénistes est grandement confirmée. Cependant, nos analyses ont repéré des données marginales qui vont dans le sens des attentes des standardistes et des dualistes. Pour dépeindre l’ensemble des musiques populaires, nous proposons une nouvelle hypothèse hétérogène, inclusive de ces quelques représentations standard que nous avançons sous le concept de « tendance hétérogène ».
Cataract surgery: impact on activities, time use and gender and power relations in rural Andhra Pradesh, India
(2015-12-21) Hewage, Neville
Social customs and the patriarchal structure of Indian society determine women’s intrahousehold status. Vision loss due to cataracts and post-surgery recovery of vision may contribute to changes in the manner in which women experience societal norms and practices, and may have an impact on gender and power relations and socio-economic status within the household. No studies which take into account socio-cultural factors and economic status have examined the impact of cataract surgery (i) on activities and (ii) time use, and (iii) on gender and power relations in rural households in Andhra Pradesh, India. This project determines what changes if any occur in gender and power relations in families in rural households in Andra Pradesh after a member has undergone cataract surgery. Qualitative analyses were performed to explore participants’ perspectives and understand the extent to which gender and power relations may change after cataract surgery. The narrative analysis showed that the profiles of the women and men in the younger and older age groups were quite different, yet there were also similarities. Certain patterns emerged following cataract surgery. While decision-making patterns did not change substantially, all participants stated that their mobility had improved after surgery and this led to a corresponding improvement in their quality of life. In addition, the quality of relationships improved for two of the women and two of the men. In addition to the narrative analysis, qualitative data from the participants assisted with understanding the complex issues related to gender and power relationships through a thematic analysis. For the most part, family composition and living arrangements did not change much as a result of cataract surgery. These matters were largely determined by customs and norms. Indeed, many of the participants described how they were able to perform various tasks, once again due to improvement in their vision. Both men and women spoke about their ability to engage in household work after the surgery. However, as women performed most of this work, cataract surgery had a greater impact on this aspect of life for women. Cataract surgery and improved vision did not have a substantial impact on gender and power relations within the context of intra-household matters as broader gender roles were more influential in this domain. Cataract sufferers were more satisfied with their lives and the benefits from surgery. Improvements in quality of life and in the activities of the participants are supported by my research findings.
Characterisation of CTR-17 and CTR-20, novel chalcone derivatives that inhibit tubulin polymerisation activity
(2015-12-17) Lindamulage, Indeewari Kalhari Silva
Agents targeting colchicine-binding sites are recognised as valuable lead compounds in the development of new anticancer drugs. Although colchicine can effectively inhibit cell proliferation, its use as an anticancer agent has not been approved by the FDA due to its inherent toxicity. To develop colchicine-binding site targeting agents with low or no toxicity, in collaboration with Rajiv Gandhi Technical University of India, several chalcone derivatives were created and examined. Preliminary studies at the Lee Lab identified CTR-17 and CTR-20 as promising leads. Their anti-proliferative activities using three human breast cancer cell lines (MDA-MB468, MDA-MB231 and MCF-7) and two matching noncancer breast cell lines (184B5 and MCF10A) were initially determined. Subsequently, nine other cancer cell lines were used to assess the broad spectrum anti-proliferative effects of the CTR compounds. Data from this study showed that CTR-17 and CTR-20 preferentially kill cancer cells 10-25 times over non-cancer cells. Data obtained from flow cytometry, confocal microscopy and Western blotting showed that CTR-17 induced a prolonged mitotic arrest, leading to cancer cell death probably via apoptosis. I also found that both CTR-17 and CTR-20 inhibited tubulin polymerisation and bound to purified tubulin fibers with a dissociation constant of 4.58±0.95 μM and 5.09±0.49 μM, respectively. CTR-17 and CTR-20 competitively inhibited the binding of colchicine to tubulin with an inhibitory concentration of 5.68±0.35 μM and 1.05±0.39 μM, respectively, suggesting that the CTR compounds bind to tubulin at a site partially overlapping the colchicine-binding site. Molecular docking studies confirmed this binding to occur via two and one hydrogen bonds between tubulin and CTR-20 and CTRiv 17, respectively. More interestingly, CTR compounds inhibit the proliferation of multi-drug resistant cell lines, which overexpress drug transporters involved in the efflux of clinically available microtubule targeting agents. In addition, the CTR compounds exhibit a synergistic relationship with paclitaxel in causing cytotoxicity to a P-glycoprotein overexpressing cell line. Therefore, these novel chalcone derivatives not only possess cancer-specific cell killing property but also the ability to exhibit similar cytotoxicity to both the multi-drug sensitive and resistant cells. Hence, CTR compounds possess substantial potential as safe and effective anticancer drugs.
Characterization of banded iron formations associated with gold mineralization: primary geochemical signatures and exploration implications
(2016-04-15) Gourcerol, Blandine
Algoma-type banded iron formations (BIFs), which represent chemical sedimentary rocks characterized by alternating layers of iron-rich minerals and chert intercalated with Eoarchean to late Paleoproterozoic volcano-sedimentary sequences, act as a favorable host rock for orogenic gold mineralization within several Archean cratons (i.e., Pilbara, Kaapvaal, Superior, Slave and Churchill). Besides this economic aspect, these Fe-rich sequences have long been appreciated as an important contributor to furthering our understanding of the geochemical evolution of the Earth. However, these deposits are in general tectonically deformed, metamorphosed and dismembered, thus making reconstruction of their depositional setting and overall geologic setting difficult. Based on four Canadian BIF-hosted gold deposits (the Meadowbank, Meliadine, Musselwhite and Beardmore-Geraldton deposits), this thesis aims to establish the depositional setting of the Algoma-type BIF using the abundance of REE+Y of chert material used as proxy of the primary signature, as well as assess gold enrichment processes based on textures and trace element zoning of variable sulfides (i.e., pyrite, arsenopyrite and pyrrhotite) and finally study if there is a particular geochemical type of Algoma-type BIF associated with gold mineralization. Laser ablation-inductively coupled plasma-mass spectrometric (LA-ICP-MS) analyses performed on chert material suggest that BIFs from the four deposits show common depositional settings illustrated by deposition in semi-closed to closed basin under variable influence of high-temperature (>250ºC) hydrothermal fluids input and detrital contamination. Moreover, evidence of late diagenetic processes involving O isotopic exchange between chert precursor (i.e., opaline material) and seawater origined fluid have been documented. According to their primary v signature, it appears that barren versus mineralized BIFs do not show any geochemical divergence suggesting that the depositional setting may influence the epigenetic gold mineralization. Based on quantitative element distribution maps combined with line traverse and spot analyses by LA-ICP-MS on sulfides, a common gold mineralizing event characterized by intense stratabound sulfide-replacement of Fe-rich material was reported in three studied deposits exhibiting a Au-As-Se-Te-Ag element association. This result suggests that metamorphic/hydrothermal orogenic processes driven by devolatilization of a common weakly to unmetamorphosed source rock have ledto generation of gold-bearing fluid which channelled into Algoma-type BIF via major crustal faults and/or shear zones within low tensile strength rocks

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