173 research outputs found
Design and Application of a Novel Optical Methane Flow Sensor to Quantify Methane Vent Sources at Upstream Oil and Gas Sites
No full textThis thesis first describes the development and characterization of an optical methane mass flux sensor, called the VentX, which was designed for use in hazardous locations such as upstream oil and gas facilities for the continuous quantification of methane emissions from point sources. Two configurations were initially described, with directly irradiated photodetectors ultimately favoured over a fully fiber-coupled version. In both configurations a methane volume fraction-dependent velocity measurement error was observed. Following component-by-component investigations of sources of optical interference, a second prototype was then designed and tested that greatly reduced this velocity measurement error, achieving a methane mass flow rate uncertainty of ±0.40 kg/h at 95% confidence and temperature induced measurement drift of <0.015 m/s/K. The VentX was then used to measure casing gas vent rates at eleven Cold Heavy Oil Production with Sand (CHOPS) wells in Saskatchewan, Canada, in conjunction with a larger aerial study of 962 sites using Bridger Photonics’ Gas Mapping LiDAR (GML). The time-resolved VentX measurements demonstrated that the discrete GML measurements could reproduce mean venting rates, despite observed temporal variability. Venting from CHOPS sites in this region was shown to be grossly underreported, with approximately 60% of the measured methane originating from wells that appeared to exceed regulated venting limits. However, preliminary economic analysis suggested that 97% of these emissions could be mitigated using readily available combustor technology with payback periods <2 years when costing methane emissions based on current carbon pricing. Finally, the VentX meter was deployed at eight oil wells in Alberta, Canada to measure unsteady venting from production storage tanks, a second key oil and gas sector source. Variable and intermittent venting was documented at multiple sites, often in conjunction with varying methane fraction. Analysis revealed the limitations of using simple gas-to-oil ratios (GOR) to estimate storage tank venting and specific recommendations were made to improve the accuracy of emission measurement and reporting. Finally, statistical analyses showed that discrete measurements of individual storage tanks using so called snapshot technologies should be treated with caution, while providing guidelines for required sample sizes to accurately measure aggregate mean emission rates in larger-scale surveys
Bank Panics, Golden Grains, and Gold Standards: Essays on North American Macroeconomic History
No full textThis dissertation is the culmination of three research projects on North American Macroeconomic History. The first two Chapters analyze the effects of deflation on the financial sector and the real economy. Chapter 1 looks at the U.S. experience between 1868 and 1913, and Chapter 2 looks at the Canadian experience between 1867 and 1913. The 3rd Chapter also looks at Canada between 1876 and 1913, but instead of inflation, it examines the "Wheat Boom" and attempts to gain a new understanding of its nature, cause, and scale. Chapter 3 also offers a preliminary discussion on how the Wheat Boom is related to the historical mistreatment of Indigenous peoples in Canada. Combined, these three works used a mixture of econometric techniques, data analysis, analytic narrative, and a little bit of modeling, to better understand North America's economic history pre-1913
Geochemistry and U-Pb Geochronology of the 1450-1425 Ma Large Igneous Province of Eastern Laurentia and 2480-780 Ma Large Igneous Provinces of Western Laurentia
No full textMesoproterozoic magmatism that is exposed on the eastern and western margins of Laurentia (North America) are interpreted to be parts of large igneous provinces (LIP). The western margin between Kimberley (British Columbia) and Yellowstone National Park (Wyoming), and the eastern margin between Labrador City and coastal Labrador are herein referred to as western Laurentia (WL) and eastern Laurentia (EL), respectively. WL intraplate magmatism was previously divided into two LIPs the: 1) ca. 1460 Ma Moyie-Purcell LIP (MPL) which consists of the i) Purcell lavas in the USA, ii) Moyie sills of the Belt-Purcell basin iii) dykes of the Tobacco Root Mountains and 2) the ca. 780 Ma Gunbarrel LIP. The MPL is composed of tholeiitic basalts, and associated with the world class Sullivan Pb-Zn deposit. EL consists of basalts of the non-mineralized Michael-Shabogamo Gabbros (MSG).This research demonstrated that at least 17 geochemical groups are present in WL of which some belong to additional previously unrecognized events. Seven geochemical groups belong to the ca. 1460 Ma MPL; 1 with the ca. 780 Ma Gunbarrel LIP, 2 with a 1590-1550 Ma Mammoth-Western Channel LIP (MWCL); 2 with ages of 2480, and 1420 Ma; and 5 undated mafic pulses. The MWCL is similar to contemporaneous volcanic rocks within the South Australia craton, which was adjacent to NW Laurentia ca. 1590 Ma. This study proposes a shared 1590 Ma plume and LIP magmatism between Laurentia, and South Australia cratons.The MSG of EL are subalkaline basalts enriched in P2O5 and K2O and are shown to represent a single event with 2 pulses based on new U-Pb ages. Each pulse is defined by a distinct [P2O5*1000]/Zr (P/Zr) ratio: 1) a high P/Zr group at ca. 1425-1435 Ma; and 2) a low P/Zr group at ca. 1435-1450 Ma. Enrichment of P2O5 and K2O is due to melting of a metasomatized subcontinental lithospheric mantle with melting facilitated by a slab window
Event-Scale Hydrologic Response in Urbanizing Watersheds of the Canadian Great Lakes Basin and Associations with Fish Richness
No full textThe cumulative impacts of urban land use on stream flow regimes and lotic ecosystems are poorly understood. Moreover, flow assessments using daily or monthly flows cannot adequately characterize event-scale flow dynamics in urbanizing watersheds. Accordingly, this empirical research examined high temporal resolution (15-minute) growing season hydrologic records in the Greater Toronto Region, Canada. Hydrologic records were matched with rainfall records to include precipitation in models. The first phase of research identified temporal trends in total runoff, rising limb event flows and rising limb accelerations in two watersheds. Results indicated dramatic changes: over a 42-year period, total seasonal discharge increased 45% in the Don and Humber Rivers during a period of stable rainfall patterns. Peak event flows and event flow variability also increased temporally. The second phase of research comprised a spatial analysis of twenty-seven watersheds ranging from 38 km2 to 806 km2 undertaken along an urban land use gradient from less than 0.1% to 88%. Urban land use had a very strong influence on total runoff and event scale runoff. Changes in runoff characteristics began at urban cover under 4%. Event flow acceleration increased, causing maximum runoff to be reached sooner as urban cover increased. The total runoff model had an interaction between watershed size and urban land use. Smaller watersheds are disproportionately affected by urbanization, as also demonstrated by the fractal relationship of stream network length and watershed area. The third phase identified associations of fish species richness with event-scale hydrologic characteristics in eight watersheds using fish data spanning approximately five decades. Maximum event flow acceleration and skew in instantaneous runoff explained a higher proportion of variation than urban percent in empirical models. Historic fish data are difficult to obtain and pose analytical challenges. By using high temporal resolution flow data, the research provides a new understanding of changes in event-scale flow regime dynamics associated with urbanization and, in turn, association of event-scale hydrology with fish richness. Compromised hydrologic stationarity is attributable to urbanization
Thin Film Precursors, Properties and Applications: Chemical Vapour Deposition and Atomic Layer Deposition of Group 4, 11 and 13 Elements and Their Oxides
No full textBrass and bronze substrates were coated by atomic layer deposition (ALD) with alumina and titania in small and large scale batches. These films were evaluated for use as protective and cosmetic coatings. Optimization of deposition for uniform coatings on individual coins and across a batch for Al2O3 and TiO2 films was performed. High-quality, uniform coatings were achieved with multi-pulse programs.The interference colours resulting from thin films of Al2O3 deposited by ALD on silicon were analyzed using a robotic gonioreflectometer. A series of thin films were deposited and their reflectivity values obtained for the visible spectrum. A comparison of these values with the predictions of computer simulations has revealed deviations from predicted reflectivities. Simulation predicts larger iridescence than what was observed. Alumina films were deposited by ALD on flat and nanostructured silicon substrates, and incorporated into PEDOT-Al2O3-silicon architectures that were then evaluated as photovoltaic devices. The reverse saturation currents observed on flat devices made with Al2O3 films were similar devices made with an SiO2 layer. The structured samples with Al2O3 showed a considerable increase in efficiency (of up to five times) over the equivalent flat samples.A new indium(III) guanidinate, (In[(NiPr)2CNMe2]3, was synthesized. Thermogravimetric analysis showed elemental indium was produced from the compound as a residual mass. Thermolysis in a sealed NMR tube showed carbodiimide and protonated dimethyl amine by 1H NMR. Chemical vapour deposition (CVD) experiments above 275 °C with air as the reactant gas produced cubic indium oxide films with good transparency.Dimeric silver(I) and gold(I) tert-butyl-imino-2,2-dimethylpyrrolidinates were synthesized and evaluated for thermal stability by thermal gravimetric analysis, differential scanning calorimetry and variable-temperature solution NMR. The compounds were used to deposit metallic films
Single-Cell Optogenetic Excitation Drives Homeostatic Synaptic Depression
No full textSummaryHomeostatic processes have been proposed to explain the discrepancy between the dynamics of synaptic plasticity and the stability of brain function. Forms of synaptic plasticity such as long-term potentiation alter synaptic activity in a synapse- and cell-specific fashion. Although network-wide excitation triggers compensatory homeostatic changes, it is unknown whether neurons initiate homeostatic synaptic changes in response to cell-autonomous increases in excitation. Here we employ optogenetic tools to cell-autonomously excite CA1 pyramidal neurons and find that a compensatory postsynaptic depression of both AMPAR and NMDAR function results. Elevated calcium influx through L-type calcium channels leads to activation of a pathway involving CaM kinase kinase and CaM kinase 4 that induces synaptic depression of AMPAR and NMDAR responses. The synaptic depression of AMPARs but not of NMDARs requires protein synthesis and the GluA2 AMPAR subunit, indicating that downstream of CaM kinase activation divergent pathways regulate homeostatic AMPAR and NMDAR depression
The BMP Ligand Gbb Gates the Expression of Synaptic Homeostasis Independent of Synaptic Growth Control
No full textSummaryInhibition of postsynaptic glutamate receptors at the Drosophila NMJ initiates a compensatory increase in presynaptic release termed synaptic homeostasis. BMP signaling is necessary for normal synaptic growth and stability. It remains unknown whether BMPs have a specific role during synaptic homeostasis and, if so, whether BMP signaling functions as an instructive retrograde signal that directly modulates presynaptic transmitter release. Here, we demonstrate that the BMP receptor (Wit) and ligand (Gbb) are necessary for the rapid induction of synaptic homeostasis. We also provide evidence that both Wit and Gbb have functions during synaptic homeostasis that are separable from NMJ growth. However, further genetic experiments demonstrate that Gbb does not function as an instructive retrograde signal during synaptic homeostasis. Rather, our data indicate that Wit and Gbb function via the downstream transcription factor Mad and that Mad-mediated signaling is continuously required during development to confer competence of motoneurons to express synaptic homeostasis
The Outsider: Elizabeth P. MacCallum, the Canadian Department of External Affairs, and the Palestine Mandate to 1947
No full textElizabeth Pauline MacCallum was Canada’s leading expert on the Middle East in the first part of the twentieth century. From 1925 to 1935, as a research analyst and author for the Foreign Policy Association (FPA), she gained international recognition for her scholarship on the problems and challenges confronting the Middle East and the British Mandate in Palestine, the central ground of dispute between the Arab and Jewish peoples. MacCallum joined Canada’s Department of External Affairs (DEA) in 1942, not as a regional specialist, but as a wartime clerk. Where there had been previously no clear official thinking regarding the Middle East, MacCallum, using a combination of expertise and persistence, slowly gained recognition among her peers for her understanding of the region. The purpose of this thesis is to examine MacCallum’s ideas about the Middle East by investigating the foundation, development, and substance of her ideas about the region. The thesis also identifies the role that she played in the Department of External Affairs and interrogates the manner in which she applied her ideas as a member of the DEA. In particular, this study assesses her part in the making of Canada’s first policy towards the Middle East, which came together in 1947. In assessing MacCallum’s ideas and her role as a member of the Department of External Affairs during the period 1942-1947, the thesis contends that she can best be understood as an outsider — a specialist in a department of generalists, a woman in a department of men, and an Arabist in a department dominated by Eurocentric and balance of power thinking. The thesis explores her efforts to put into practice her ideas as a basis for Canada’s approach to the Arab-Zionist dispute. The thesis further demonstrates that MacCallum made clear the dangers that the problem of Palestine posed to international peace and security, and the likely split that it would cause among the Great Powers over the territory’s fate. She opposed the division of Palestine between its Arab and Jewish peoples in 1947 and predicted the Middle Eastern war soon to come
State of Disaster Risk Reduction at the Local Level: A report on the Patterns of Disaster Risk Reduction Actions at Local Level
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