OPUS: Open Ulethbridge Scholarship
Open ULeth Scholarship (OPUS) is the University of Lethbridge's open access research repository. It contains a collection of materials related to research and teaching produced by the academic community.
Self-archiving your research in OPUS is one way to meet Open Access policies of granting agencies. It is important to retain your final, post-peer-reviewed drafts for submission to OPUS, as this is often the only version publishers will allow to be archived. Click here for information on the U of L Open Access Policy.
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Lewis-acid behavior of tungsten hexafluoride towards mixed ligand systems, phosphine oxides and tridentate terpyridine
(Lethbridge, Alta. : University of Lethbridge, Dept. of Chemistry and Biochemistry, 2024) Adamitz, Taylor Peter Karl; University of Lethbridge. Faculty of Arts and Science; Gerken, Michael
The Lewis-acid behavior of WF6 towards mixed ligand systems, phosphine oxides, and tridentate terpyridine has been investigated. Because of the known stability of 1 : 2 adducts of WF6 with main-group-donor ligands, the reaction of WF6 with stoichiometric amounts of the two bases pyridine and P(CH3)3 was studied, resulting in crystal growth of WF6(py){P(CH3)3}•CH2Cl2. The WF6(py){P(CH3)3} adduct adopts a capped trigonal prismatic geometry, prevalent for WF6 adducts. However, alongside the presence of the desired adduct, numerous side products were identified by NMR spectroscopy. Reactions of WF6 with OP(C2H5)3 and OP(C6H5)3 were conducted at both ambient temperatures and at –80 ºC invariably led to deoxofluorination with the formation of F2PR3 and [FPR3]+, R = C2H2, C6H5, being identified by NMR spectroscopy. Additionally, evidence for the new WOF4{OP(C2H5)}2 adduct was obtained by NMR spectroscopy. Lastly, the ability of WF6 to relinquish a fluoride when stabilized by nitrogen bases, alongside its ability to act as a fluoride acceptor, has been exploited to yield the [WF5(terpy)][WF7] salt as an autoionization product. This salt was fully characterized by multinuclear NMR and Raman spectroscopy, as well as X-ray crystallography and further studied computationally. The octacoordinated [WF5(terpy)]+ cation in [WF5(terpy)][WF7]•SO2 has a bicapped trigonal prismatic geometry as verified by the τ8 geometry index. Tungsten hexafluoride in the [WF7]– anion was displaced upon reacting the salt with SbF5•SO2, yielding [WF5(terpy)][SbF6].
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Impacts of mountain pine beetle outbreak and wildland fuel reduction treatments in Jasper National Park, Alberta, Canada
(Lethbridge, Alta. : University of Lethbridge, Dept. of Geography and Environment, 2024) Skretting, Tristan N.; University of Lethbridge. Faculty of Arts and Science; Chasmer, Laura
Wildland fuels are deviating from traditional described fuel complexes due to climate- mediated pressures and anthropogenic alteration. However, technological advances have also increased the capacity to obtain fuels information at higher detail across the landscape to capture these changes. Quantifying fuel baselines in disturbed and altered states is paramount to understanding the impact on wildland fire potential. This thesis examines fuels that deviate from traditional fuel types in the montane region of Jasper National Park, Alberta, Canada using field measurements and coincident airborne lidar data. First, the impacts of mountain pine beetle on fuels over a range of severity within the same temporal phase of outbreak are investigated. With increasing severity, overstory and subcanopy fuel loading significantly lowered, forest floor composition became more herbaceous, and organic layer loading increased. Severely impacted stands also exhibited less than half the amount of coniferous seedling recruitment than lightly impacted stands, which could signal a shift in regeneration away from closed-canopy conifer stands in this region. Second, fuel treatment efficacy over two decades was evaluated using field and lidar-derived canopy metrics. Though surface fuels in field-measured stands remained similar over time, stem density, canopy cover, canopy bulk density, and canopy base height varied significantly over time since management. Stand-level fire modelling at dry to extreme weather percentiles (90th – 97th) predicted that stem density and canopy fuels were sufficiently reduced to prevent active crown fire in treated stands, but surface fuels and low canopy base height were conducive to torching of individual trees in most scenarios and treatment years. This research provides critical insight into the variability within both managed and disturbed fuels over time, and the potential impact on fire behaviour as high fire weather indices occur more often in a warming climate.
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A study of text summarization with graph attention networks
(Lethbridge, Alta. : University of Lethbridge, Dept. of Mathematics and Computer Science, 2024) Ardestani, Mohammadreza; University of Lethbridge. Faculty of Arts and Science; Chali, Yllias
This study aimed to leverage graph information, particularly Rhetorical Structure Theory (RST) and Co-reference (Coref) graphs, to enhance the performance of our baseline sum- marization models. Specifically, we experimented with a Graph Attention Network archi- tecture to incorporate graph information. However, this architecture did not enhance the performance. Subsequently, we used a simple Multi-layer Perceptron architecture, which improved the results in our proposed model on our primary dataset, CNN/DM. Addition- ally, we annotated XSum dataset with RST graph information, establishing a benchmark for future graph-based summarizing models. This secondary dataset posed multiple chal- lenges, revealing both the merits and limitations of our models.
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Cost-effective batch-based migration strategies for NewSQL-based big data systems
(Lethbridge, Alta. : University of Lethbridge, Dept. of Mathematics and Computer Science, 2024) Vadlamudi, Naveen Kumar; University of Lethbridge. Faculty of Arts and Science; Osborn, Wendy
Modern, high-performance applications demand scalable and efficient databases, leading
to the evolution of NewSQL systems. The challenge lies in migrating data from Shardingsphere
with PostgreSQL to AWS (AmazonWeb Services) cloud object storage. Implementing
batch migration algorithms in Apache Spark, specifically targeting Delta Lake format,
introduces complexities to ensure seamless data integration and storage within AWS environments.
This thesis explores tailored batch-based migration algorithms for transferring data from
Shardingsphere with PostgreSQL to AWS cloud object storage, emphasizing performance
optimization by transferring the data faster. The study evaluates various batch loading techniques
in Apache Spark, including sequential and concurrent strategies for shard-by-shard
and aggregated-shards based algorithms. These techniques aim to maximize efficiency in
storing data in Delta Lake format within AWS cloud storage, facilitating effective data
management, visualization, and utilization for modern applications, business intelligence,
AI and ML. Leveraging the Lakehouse architecture for integrated data processing and analytics.
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The effect of minimum wage increase on employment in Canada
(Lethbridge, Alta. : University of Lethbridge, Dept. of Economics, 2024) Quarmson, Isaac Sarfo; University of Lethbridge. Faculty of Arts and Science; Ali, Md Kamar
This research investigates the effect of minimum wage increases on employment in Canada, focusing on three age groups: 15-19, 20-24, and 15-24. The study utilizes provincial data from 1983 to 2022 and employs Neumark's (2001) pre-specified design to analyze the ratio format of the explanatory variables. Additionally, this study slightly modifies Neumark’s design to analyze the explanatory variables in a non-ratio format. The model results indicate no statistically significant relationship between minimum wage and employment for all age groups for Neumark’s (2001) pre-specified model and the modified form. The overall results suggest that firms may respond to minimum wage increases by adjusting other variables such as non-wage benefits, prices, profits, etc.