Analysis of Canadian Tropospheric Ozone Measurements from Geostationary Orbit and An Assessment of Non-Coincident Limb-Nadir Matching for Measuring Tropospheric Nitrogen Dioxide

This thesis work attempts to improve the quality of surface-level pollutant concentrations retrieved from satellite-borne optical instruments. In the first part of the present work, an analysis is performed to determine potential benefits of implementing a different radiative transfer model than the one planned for retrieving Canadian tropospheric ozone concentrations with future measurements from the Tropospheric Emissions: Monitoring of Pollution (TEMPO) optical instrument, planned to be launched in 2022 into geostationary orbit to measure tropospheric pollutants over the majority of North America. The plane-parallel Earth-atmosphere geometry assumption for multiple-scattered electromagnetic radiation in the planned radiative transfer model for the TEMPO ozone retrieval algorithm has minimal effect for heritage instruments that look at angles close to straight down and measure at local times where the Sun is far above the horizon. However, it is demonstrated in the present work for simulated TEMPO measurements over the Canadian Oil Sands that the retrieval error for a radiative transfer model with a plane-parallel geometry can reach approximately 15% at 13:00 local time, 25% in March or September near local sunrise, 50% in June near local sunrise, and 80% in December near local sunrise, while a radiative transfer model with a spherical geometry results in error up to an order of magnitude smaller in each case. Further work is required to assess the effects of the geometry assumptions on different orders of scattering and of measurement noise. In the second part of the present work, a novel method of estimating tropospheric NO2 pollution using non-coincident limb- and nadir-viewing instrument measurements is further assessed with a reanalysis using new datasets produced by the Ozone Monitoring Instrument (OMI), the Optical Spectrograph and Infrared Imager System (OSIRIS), and a photochemical box model, and an analysis using OSIRIS and the TROPOspheric Monitoring Instrument (TROPOMI). A bias is demonstrated in the current publicly available OSIRIS NO2 density profile data, leading to the development of an updated dataset that is shown to agree with a previously validated dataset within retrieval error bounds above the tropopause. The OSIRIS-OMI reanalysis demonstrates biases of up to 0.5*10^15 molecules/cm^2 due to the different photochemical box model input parameters and up to 0.2*10^15 molecules/cm^2 due to the use of the latest OMI NO2 dataset. The OSIRIS-TROPOMI analysis demonstrates a positive average bias of approximately 0.5*10^15 molecules/cm^2 in the limb-nadir matching with TROPOMI relative to that with OMI due to TROPOMI-OMI tropospheric and stratospheric NO2 column density biases. Error range estimates of photochemical box model input parameters and of different versions of OMI datasets, further analysis of local and yearly dependencies of OSIRIS-OMI limb-nadir matching biases, and further studies on latitudinal and seasonal dependencies of TROPOMI-OMI dataset biases are recommended for future work

Influence of pulse crops on abundance of arbuscular mycorrhizal fungi in a durum-based cropping system

Non-Peer ReviewedPulses are an important component in crop rotations in southern Saskatchewan. Besides their capability to fix nitrogen, pulse crops establish a strong symbiotic relationship with arbuscular mycorrhizal (AM) fungi, which have been shown to increase nutrient and water uptake through hyphal extensions in the soil. Incorporating strongly mycorrhizal crops in a rotation may increase inoculum levels in the soil and benefit the growth of a subsequent crop. The objective of this study was to determine if AMF colonization of a durum crop is significantly affected by cropping history and to assess the impact of pulses in crop rotations on the abundance of AMF communities in the soil. In 2004 and 2005, soil and root samples were taken on durum with preceding crops of chickpea, pea, lentil, canola, and durum. Arbuscular mycorrhizal colonization was significantly lower in durum roots following canola in both years. Phospholipid fatty acid analysis (PLFA) was completed to analyze the relative abundance of AMF, saprophytic fungi, and bacteria in the soil. These results demonstrated that although previous crop may play a role in microbial community structure, it is not the only influencing factor

The Quantum Socket: Three-Dimensional Wiring for Extensible Quantum Computing

Quantum computing architectures are on the verge of scalability, a key requirement for the implementation of a universal quantum computer. The next stage in this quest is the realization of quantum error correction codes, which will mitigate the impact of faulty quantum information on a quantum computer. Architectures with ten or more quantum bits (qubits) have been realized using trapped ions and superconducting circuits. While these implementations are potentially scalable, true scalability will require systems engineering to combine quantum and classical hardware. One technology demanding imminent efforts is the realization of a suitable wiring method for the control and measurement of a large number of qubits. In this work, we introduce an interconnect solution for solid-state qubits: The quantum socket. The quantum socket fully exploits the third dimension to connect classical electronics to qubits with higher density and better performance than two-dimensional methods based on wire bonding. The quantum socket is based on spring-mounted micro wires the three-dimensional wires that push directly on a micro-fabricated chip, making electrical contact. A small wire cross section (~1 mmm), nearly non-magnetic components, and functionality at low temperatures make the quantum socket ideal to operate solid-state qubits. The wires have a coaxial geometry and operate over a frequency range from DC to 8 GHz, with a contact resistance of ~150 mohm, an impedance mismatch of ~10 ohm, and minimal crosstalk. As a proof of principle, we fabricated and used a quantum socket to measure superconducting resonators at a temperature of ~10 mK.Comment: Main: 31 pages, 19 figs., 8 tables, 8 apps.; suppl.: 4 pages, 5 figs. (HiRes figs. and movies on request). Submitte

Prostaglandin E2 drives cyclooxygenase-2 expression via cyclic AMP response element activation in human pancreatic cancer cells.

Cyclooxygenase-2 (COX-2) is constitutively expressed in most human primary carcinomas and with its synthesized product, prostaglandin E2 (PGE2), appears to play important roles in tumor invasion, angiogenesis, resistance to apoptosis and suppression of host immunity. However, the molecular mechanisms that control COX-2 expression are unclear. The purpose of this study was to clarify the mechanism of basal and PGE2-mediated COX-2 expression in the highly metastatic L3.6pl human pancreatic cancer cell line. Using RNA interference to disrupt the expression of CREB and the NF-kappaB p65 subunit, we found that both are involved in maintaining basal COX-2 expression in L3.6pl cells. We also demonstrated that PGE2 increased the cyclic AMP concentration, thereby activating protein kinase A (PKA), which in turn phosphorylated the cyclic AMP response element binding protein (CREB), leading to interaction with the cyclic AMP response element in the promoter region of the COX-2 gene. Immunocytochemical analysis confirmed that PGE2 stimulated the translocation of PKA to the nucleus and increased the immuno-reactivity of phosphorylated CREB. Pretreatment with the PKA selective inhibitor H 89 and the E-prostanoid receptor 2 inhibitor AH 6809 reduced COX-2 upregulation by PGE2. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay results further suggested a role for CREB in COX-2 transcriptional control. Understanding the pathways that control COX-2 expression may lead to a better understanding of its dysregulation in pancreatic carcinomas and facilitate the development of novel therapeutic approaches

Production of O(1D) following electron impact on CO2

We have studied the excitation of metastable O(1D) following dissociative excitation of CO2 in the electron impact energy range from threshold to 400 eV. A solid Ne matrix at ∼20 K forms the heart of the detector. This is sensitive to the metastable species through the formation of excited excimers (NeO*), The resultant excimer radiation is readily detected, providing a means of measuring the production of the metastables. Using a pulsed electron beam and time-of-flight techniques, we have measured the O(1D) kinetic energy spectrum and its relative production cross sections as a function of electron impact energy. Threshold energy data are used to gain information about the excitation channels involved. In addition, an emission excitation function for the red photons, emitted in coincidence with the exciting electron pulse, has been measured in the 0–400 eV energy range