Graduate Theses and Dissertations

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https://hdl.handle.net/10388/381

This collections holds all University of Saskatchewan graduate level electronic theses and dissertations (ETDs) published since 2005. More than 700 print theses published before 2005 have been digitized and added to the collection as well.

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Economic Analysis of Beneficial Management Practices Adoption on Canola Production in Canada: Evidence and Policy Implications from First Nations in Saskatchewan
(2024-08-29) Ampomah, Samuel; Natcher, David C.; Arcand, Melissa; Liebenehm, Sabine
This study utilized the Decision Support System for Agrotechnology Transfer (DSSAT) model to examine the effect of farm practice such as fertilizer application on canola yield from 2017 to 2040 on the Mistawasis Nêhiyawak First Nation reserve in central Saskatchewan. Following three separate fertilizer application scenarios, the results highlighted the effectiveness of integrating organic and inorganic fertilizers as BMP technology under the Integrated Nutrient Management (INM) practice for enhancing crop productivity. The financial analysis further showed the economic viability of BMP technology adoption, particularly in increasing nitrogen fertilizer application beyond 135 kg/ha in optimizing returns to farmers, with higher net profits and positive net present value (NPV) values compared to the base technology. Sensitivity analysis emphasized the importance of considering uncertainties in discount rates and crop prices, indicating the significance of sustainable farming practices for ensuring enduring economic viability. This study provides valuable insights into optimizing fertilizer management practices and promoting sustainable agriculture in canola production, particularly on First Nation reserves in Canada.
LANDSCAPES OF LOVE: WANDAT WOMEN AND THE POLITICS OF REMOVAL, 1795-1910
(2024-08-28) Kelly, Mckelvey; Labelle, Kathryn; Hoy, Benjamin; Troupe, Cheryl; Hackett, Paul; Kugel, Rebecca; Englebert, Robert; Cunfer, Geoff
My dissertation is a community-engaged history guided by an Advisory Council of Wandat/Wendat women including Chief Emeritus Janith Atrondahwatee English (Kansas), Principal Chief Judith Trǫnyáęhk Manthe (Kansas), Second Chief Louisa Yarǫnyewáʔe Libby (Kansas), Faith Keeper Catherine Taǫmęʔšreʔ Tàmmaro (Ontario), Faith Keeper Sallie Tewatronyahkwa Cotter Andrews (Oklahoma), and Faith Keeper and lawyer Barbara Datǫgya’ha Aston (Oklahoma). This methodological approach built on direct collaboration with these women underscores the project’s commitment to authentically representing their perspectives on their shared history. It examines structures of power and control within North American Indigenous removal and diaspora, focusing on the responses of Indigenous women to the historic trauma of removal in nineteenth century America. I argue that Wandat women protested removal and erasure of the Wandat from their lands in Tsaʔⁿduskeh, Uhížuʔ (now Upper Sandusky, Ohio) and Wyandott City (now Kansas City, Kansas) in the wake of American expansion in the 1830s. These women fought for their land largely using petitions and letter-writing campaigns to preserve community culture and overcome generations of colonial threats. This research challenges pervasive Settler myths that portray Indigenous peoples as timeless entities confined to the edges of urban metropolises or isolated on reserves. My research demonstrates that Indigenous women maintained strong connections to their homeland(s), even after they were forced to leave. Contrary to narratives of destruction and erasure, this research reveals the continued presence and agency of Indigenous women in city spaces. It reimagines spaces traditionally seen as Settler or colonial, such as Kansas City, Kansas, as Indigenous ones highlighting the roles of Wandat women in land ownership, agricultural development, and the establishment of cultural institutions like churches and schools. These actions both resisted colonization as well as contributed to the making of cities, states, and countries. Thus, my work positions Indigenous women as central actors in the creation and maintenance of place.
Non-Destructive Estimation of Leaf Area Index(LAI) Using Image Data
(2024-08-27) Sediqi, Tansu; Noble, Scott; Helgason, Warren; Meda, Venkatesh
This study investigated using image data to estimate the Leaf Area Index (LAI) for wheat (Triticale aestivum L.). The calculation of LAI involved the utilization of light interception, and the estimation process involves creating a model using metrics extracted from Near-Infrared (NIR) and visible light image data. Line quantum sensors were used to collect above- and below-canopy light measurements. Standard models were used to calculate LAI based on these measurements. To address the effects of the sun azimuth angle, corrections were applied to the LAI values, effectively eliminating its impact on the determinations. The assessment of canopy coverage used in this study involved NIR and visible light images. To estimate LAI non-destructively, linear regression models were constructed, incorporating a set of metrics from the mentioned imaging modalities and the date as a proxy for the maturity of the wheat canopy. The performance of these models was evaluated using root mean squared error (RMSE) and adjusted coefficient of determination (R2). Through a comparison of these models, it was concluded that LAI was best estimated using NIR images, rather than visible-light images. Moreover, the most effective model for the estimation of LAI included only canopy coverage and maturity proxy as input parameters. Height was not an important factor in this case. The dataset examined contained a set of wheat varieties. To improve the power of LAI estimation models, the study employed a clustering technique. Rather than using a single, generic model for LAI estimation across all varieties, the proposed clustering strategy involves clustering the dataset and developing a model for each distinct cluster. This departure from the one-size-fits-all approach generated more precise LAI estimations for each cluster, ultimately enhancing the overall predictive accuracy of the models. This not only enhanced comprehension of LAI dynamics but also underscored the significance of personalized strategies in agricultural research to achieve more precise and applicable results. However, there are certain limitations to consider. The clusters showed inconsistencies, indicating possible difficulties in putting them into practice. While the suggestion of clustering exists, the specific approach to resolving these inconsistencies remains uncertain.
FOOD INSECURITY AT THE UNIVERSITY OF SASKATCHEWAN DURING THE COVID-19 PANDEMIC
(2024-08-26) Pasloski, Nicole P; Gertler, Michael; Quinlan, Elizabeth; Cheng, Hongming; Engler Stringer, Rachel
Food insecurity has become a growing issue for many Canadian subpopulations. When the COVID-19 pandemic began in March of 2020, many food-insecure households and individuals were unable to use previously relied-upon services or practises to ease their struggles with food insecurity. This case study focuses on post-secondary students as one disproportionately affected subgroup and uses a critical ethnographic approach paired with an autoethnographic lens to explore the experiences of food insecurity within the population during the pandemic. Drawing on one-on-one interviews and interrogation of her own lived experiences, the researcher draws out the complex, comingled, and often painful realities of food insecurity in the lives of university students. Participants’ struggles to obtain sustenance and their compulsion to minimize the difficulties they face was explored through discussion of matters that particularly affect post-secondary students at the University of Saskatchewan. Combining these intimate interviews with the first-person accounts and reflections of the researcher, who also struggled with food insecurity, resulted in a multiplicative enrichment to the analysis and depth of understanding. The interviewees openly shared their views and perspectives on their distressing experiences struggling with food access during a difficult period in history and painted a somewhat dismal picture of the challenges faced by students. However, despite the critiques they offer of structural barriers, neglect, and inadequate supports, the participants and the researcher remain hopeful, and proffer ideas on how to make changes that could improve the food security of future cohorts of post-secondary students.
THIN MAGNETIC FILM STORAGE DEVICES
(1965-11) Tickle, Andrew C.; Booth, A. D.
Binary information may be represented by domains in a thin uniaxial magnetic film. By means of suitable sequences of applied fields domains may be propagated to a point where their data -representing state may be detected. The. characteristics of devices working on the principle have been investigated for different modes of operation. The nucleation and subsequent morphology of domains has been studied with particular regard to the modes in which. spurious changes occur the data-representing states of domains as they are propagated. The operating tolerances on the magnetic driving fields depend on the difference between Hs, the field required to nucleate domains, and Ho, the field required to move domain boundaries. -1-k corresponds to the anisotropy field, Hk. By increasing the uniaxial anisotropy, by changing the film composition, r may be considerably • increased. Hc, may be controlled independently by varying the film thickness. Spurious changes in the data -representing states of domains are caused by magnetostatic interactions during relaxation of the domains after the driving field pulses terminate. These magnetostatic effects may be modified by a magnetic biassing field, which results in a considerable increase in operating tolerances. Applications for sequential-access devices employing domain wall motion are considered and shown to be most suitable for relatively small memory systems.
CHARGE TRANSPORT MEASUREMENTS ON AMORPHOUS SELENIUM PHOTORECEPTOR FILMS
(1988-08) Thakur, Randhir Paul S.; Kasap. S. O.
Time of Flight Transient Photoconductivity experiments were performed on a range of single layer amorphous selenium based xerographic photoreceptor films for charge transport studies. Amorphous selenium photoreceptor films prepared in the Material and Devices Laboratory of the University of Saskatchewan and obtained from industrial suppliers were investigated. Charge carrier drift mobility and trapping time or lifetime were measured as a function of the applied field. The dependence of the charge transport parameters on the preparation conditions and origin of selenium was also studied. The saturated residual potential was calculated from normal Time of Flight measurements in the Repetitive Mode. This simple and inexpensive technique provided comparable results to those obtained from expensive Xerographic measurements. Normal Time of Flight experiments carried out on a range of xerographically characterized amorphous selenium photoreceptor films exhibited a good correlation between Time of Flight photocurrent signals and cycled-up xerographic residual voltages. An interrupted Transit Time Technique identified two species of traps and allowed the extraction of the hole trapping and release times, even when the conventional Time of Flight signal showed very little evidence of trapping. The apparatus enabled RC transient free Interrupted Transit Time as well as delayed and advanced photoexcitation measurements to be carried out on amorphous solids. During the flight of photoinjected carriers, the applied bias was removed and then reapplied after a variable delay. The large RC voltage transients occurring at the "on" and "off" times of the supply voltage which would normally obliterate the small photocurrent signal in conventional Time of Flight experiment were completely eliminated by using an inverse of the applied bias and variable nulling capacitor. For the first time the technique was used to examine the trapping kinetics in vacuum deposited amorphous selenium photoreceptor films during charge transport.
A MICROPROCESSOR BASED RESIDENTIAL ENERGY CONSUMPTION MONITOR
(1985-03) Tempel, Philip L.; Clewes, T. W.; Huff, J. G.
The design of a novel appliance load monitoring system is described. The system comprises a data collection unit, located at the residential distribution transformer, and distributed load monitoring transponders, located in the customer's home. Communication between the data collection unit and the transponders is over the residential and utility wiring using a frequency shift powerline carrier modem. The remote transponders are capable of metering real and reactive power on a demand and peak basis. A isolated pulse accumulator input is provided for interface to pulse initiation meters. Load control under the command of the central data collection unit is provided. The thesis describes central unit design generally and the transponder hardware and software in detail.
ELECTRON AND HOLE TRANSPORT IN STABILIZED A-SE FOR X-RAY IMAGING
(1997-12) Tanha, Reza; Kasap. S. O.
Time-of-flight (TOF) transient photoconductivity measurements were carried out on thermally evaporated, vacuum deposited selenium alloy photoconductor films, known as stabilized amorphous selenium (a-Se, nominal composition a-Se:0.2-0.5%As, 20ppm Cl), of various thicknesses. This study utilizes three different analytical methods to evaluate the transit time and drift mobility of the charge carrier. This work also investigate the effect of three different top contacts, gold, nickel and platinum, on the electronic properties of the photoreceptor. It is concluded that the contact type has no significant effect on the behavior of the photogenerated electron and hole pairs. TOF measurements were also used on several stabilized a-Se samples to determine the dominant factor in charge carrier dispersion mechanism. Dispersion appears to increase linearly with an increase in the collected charge, due to coulombic repulsion of the carriers. However, if the effect of coulombic dispersion is eliminated, the dominant factor is concluded to be the multiple trapping of the carriers in transit. This finding is important for x-ray imaging, since it defines the process which controls the speed and resolution of the device. Finally the TOF measurements were used to evaluate the effect of bulk space charge build up in the photoreceptor due to charge injection by electrodes and/or repetitive photoexcitation of the sample. No net bulk space charge build-up was observed up to — 10 seconds for all the three contacts investigated.
Simulator/Silicon Compiler for Systolic/Wavefront Arrays
(1989-07) Tandri, Sudarsan; Abd-El-Bar, Mostafa; McCrosky, Carl D.
Previous Systolic/Wavefront array (SWA) design tools have focussed on either simulation or integrated circuit fabrication, but not on both. It is argued that specification, simulation and fabrication of these arrays should be integrated. Specification in one language must drive both simulation and fabrication. Potential errors in translating simulation specifications to silicon compilation would be eliminated. In this thesis, we introduce Systolic and Wavefront Array Definition Language (SWADL), which integrates specification, simulation, and fabrication of systolic and wavefront arrays. SWADL specifications are simple and abstract permiting high level design of SWA's. The design of SWADL, its compiler, and experience with its use are reported.
MIS SINGLE CRYSTAL SILICON SCHOTTKY BARRIER SOLAR CELLS
(1981-09) Tan, Siew Yong; Dey, S. K.
The high cost of conventional diffused homojunction solar cells has been the major stumbling block for largescale terrestrial application of photovoltaic energy converters. Metal-Insulator—Semiconductor Schottky Barrier Solar Cells (MIS SBSC) are currently of considerable interest due to their potential for low cost junction barrier formation and more importantly, their compatibility with non—single crystalline materials. An experimental study involving design, fabrication and testing of MIS SBSC on p-type<100> single crystal silicon by vacuum evaporation technique is described. Parameters considered include substrate resistivity; Schottky metals; grid patterns; antireflection (A/R) materials; thicknesses of the interfacial insulator, Schottky metals and A/R coatings; active solar area; surface preparation and interfacial oxide formation techniques; deposition rate and vacuum condition. Also presented in this thesis are a systematic experimental investigation and evaluation of the structure, as well as a qualitative study of the spectral response and stability of the devices fabricated. With the improved process parameters, stable and reproducible semi-transparent metal MIS SBSC of 11-12% efficiency are developed with extreme cases of 15-16% for Al/SiOx/P.,Si configuration. An experimental study of the effects of active solar areas has revealed that these devices are limited mainly by surface resistance. Advances along this course is expected to enhance the potential of the MIS structure for a low cost production process. Moreover, the low temperature(420-500°C) fabrication process has clearly illustrated its adaptability to non-single crystalline semiconductors. A direct spin-off of the present work is a new in-lay approach in the fabrication of mechanical masks allowing "fingers" line widths of few microns to be possible.
Spectral Stability of Plasma Flow in Magnetic Nozzle
(2024-08-26) Feng, Hunt; Smolyakov, Andrei; Koustov, Sasha; Xiao, Chijin; Spiteri, Ray
In this thesis, spectral stability of plasmas is understood as an eigenvalue problem of linearized plasma equations describing time dynamics near some equilibrium state. Presence of eigenvalues with positive imaginary part would indicate the instability when small fluctuations will grow (typically exponentially) in time. A particular focus is the stability of plasma with stationary flows, in particular, flows in the magnetic nozzle. Magnetic nozzle, or magnetic mirror configurations, with converging-diverging magnetic field are used to accelerate plasma in plasma propulsion systems (magnetic Laval nozzle) and in fusion devices aiming to confine plasma and reach controlled thermonuclear fusion. We consider the linear stability of plasma folws under different boundary conditions. The linearized plasma equations are discretized and spectral stability problem is reduced to a polynomial eigenvalue problem. We found that the subsonic and supersonic folws are stable for Dirichlet boundary conditions. The supersonic flow is unstable for the mixed (fixed-open) boundary conditions. The subsonic flow has conflicting modes; i.e., the ground mode is unstable while the rest are stable. We show that different spectral methods, spectral-collocation and spectral-Galerkin methods agree. Phenomena of spectral pollution resulting in spurious unstable modes is discussed. By studying the convergence of different modes, we successfully eliminated the spurious modes. The stability problem of the transonic velocity profile has an additional difcfiulty due to the singularity at the sonic point, the point when the folw velocity is equal to the local sound velocity. At this point, the coefficient in front of the highest derivative of the differential eigenvalue equation becomes zero. In this case, the direct application of the spectral methods is problematic. To solve this problem, we solve the equation near the singularity by the Frobenius method and then use the regular solution with the shooting method to find the eigenvalues. We find that the transonic accelerating velocity profile is stable.
ECONOMIC DETERMINANTS OF FOOD SECURITY IN NORTHWEST TERRITORIES (NWT), CANADA
(2024-08-23) Tetteh, OSCAR Bismark; Liebenehm, Sabine sabine.liebenehm@usask.ca; Natcher, David david.natcher@usask.ca; Yang, Yang yang.yang@usask.ca; Henry, Carol carol.henry@usask.ca; Hesseln, Hayley h.hesseln@usask.ca
ABSTRACT In recent years, food insecurity, specifically food access and food availability has deteriorated in many parts of the world, including the Northwest Territories (NWT) of Canada. Food insecurity is associated with adverse mental health, obesity, chronic illnesses, and poor academic out-comes. Recent research in NWT aimed at understanding the determinants of food insecurity suggests that high transportation costs, food spoilage, inadequate distribution, and the lack of sales alternatives result in severe food insecurity. These studies, however, are based on small sample sizes from selected communities. This thesis studies the current trends of food insecurity and its correlation with socioeconomic factors across NWT’s six regions and 34 communities. To do so, I gathered secondary data at community level from various sources, including the NWT Bureau of Statistics and Statistics Canada over different time periods. The measurement of food insecurity rests on the indication of what percentage of households per community were worried about not having enough money to buy food in 2018. This indicator reflects food insecurity in the sense of a lack of financial resources to access food and relates to the demand side. The socioeconomic factors considered relate to both the demand side and the supply side as they can affect the percentage of house-holds worried of not having enough money to buy food through factors that affect households’ ability to access food and factors that affect food availability, respectively. The results indicate a north-south divide: In northern regions such as Beaufort Delta, Sahtu, Thcho, and Dehcho, 31%, 31.2%, 55.1%, and 31.5% of households, respectively, are concerned about not having enough money to buy food, while in southern regions such as South Slave and Yellowknife, the percentages are 18% and 17%, respectively. On average, the four northern regions are more than twice as likely to be food insecure as the two southern regions. Also, the results of the descriptive analysis show that regions with more dispersed households, no active mines, and only a few small-sized grocery stores are associated with higher levels of food insecurity. Furthermore, the Ordinary Least Squares (OLS) results show that communities with higher population densities, and a higher percentage of its population participating in tradition-al activities are associated with higher food insecurity. Also, communities that benefit from Nutrition North Canada’s (NNC) food subsidy, as well as communities that have a more educated population, or better transportation facilities such as all-weather roads and airport facilities are associated with lower food insecurity.
Developing a unified framework of reading and attention through attentional-oculomotor exercise and cognitive neuroscience examinations of frontal-eye-field structure and function
(2024-08-23) Kress, Shaylyn; Borowsky, Ron; Gould, Layla; Mickleborough, Marla; Giaschi, Deborah; Stockdale, Keira; Farthing, Jon
Reading is a cognitive skill that involves integrating multiple processes. One of these processes is attention, but the theoretical models of reading and attention are typically considered separately. Given the role of attention in successful reading, and research that suggests attention is affected in dyslexia, this thesis proposes a unified framework of reading + attention to better understand how these cognitive processes work together, with a focus on the attentional process of oculomotor activity. Experiment 1 developed a novel approach to isolate orthographic lexical decision processing and a gaming-style health bar task to manipulate attentional-oculomotor exercise. Through manipulation of stimulus location, Experiment 1 suggested peripheral attentional-oculomotor exercise was more beneficial to reading performance than central attentional-oculomotor exercise, supporting recent theories of oculomotor activity in reading. Experiments 2 and 3 further developed this paradigm, and observed benefits of both peripheral and central attentional-oculomotor exercise on reading suggesting fine-grained oculomotor processes may also play a role in the reading + attention relationship. All three of these studies observed word frequency of lexical targets was associated with improved performance in the lexical decision task while bigram frequency of sublexical foils was associated with worse performance, which will be a useful measure for future studies that are attempting to isolate these processes. Experiment 4 used data from a hybrid reading and attention fMRI experiment to localize the interaction between reading and attention in the frontal-eye-field – a region involved in oculomotor activity. An interaction in fMRI activation was observed in the frontal-eye-field, supporting theories of the region’s involvement in reading and attention. The frontal-eye-field region of interest identified in Experiment 4 was used in Experiment 5 to identify the connectivity profile of the frontal-eye-field with other reading + attention regions. Connections with the basal ganglia, cerebellum, and superior parietal lobule were highlighted, which are implicated across a number of components in the reading and attention networks. Using these findings as a framework, a combined model of reading + attention was proposed to serve as a foundation for future research on reading + attention. The findings will have implications in both the research fields of reading and attention, as well as applications in the development of reading interventions for dyslexia, which can benefit from attentional-oculomotor exercise.
THE MOBILITY OF POLICE-CITIZEN INTERACTIONS OPEN DATA
(2024-08-23) Field, Brennan; Blakely, Jill A; Patrick, Robert J; Berdahl, Loleen D; Bell, Scott M; Schneider, Christopher J
In 2014, as protests against police brutality spread throughout the United States, a new policy began to emerge that sought to address the public’s declining trust in law enforcement through the release of previously withheld information on daily interactions between police and citizens. As part of a larger movement promoting government transparency, often called open data, this novel application of open data to policing was a dramatic change compared to the status quo concerning police data on these interactions in the United States. This dissertation examines the genesis, development, and spread of this policy, referred to as police-citizen interactions open data (PCI open data), focusing on the role played by the White House-led Police Data Initiative (PDI). This is achieved through developing an integrated analytical framework that combines insights from the assemblage/mobility approach with institutional perspectives on police agencies, which is then applied on original qualitative and quantitative data. This dissertation emphasizes the importance of informational infrastructure assemblages, such as the PDI, in facilitating policy mobility, and presents evidence of PCI open data adoption and mutation among data transparency policies utilized by American police.
Measuring alignment of non-SDK Android interface guidelines
(2024-08-23) Silva, George; Stakhanova, Natalia; Derek, Eager; Debajyoti, Mondal
The abstract of this item is unavailable due to an embargo.
Modelling & Experimental Investigations Of Distal Radius Surface Strain Distributions During Off-Axis Loading
(2024-08-23) Adam, Madison J.P.; Johnston, James (J.D.); Kontulainen, Saija; Dolovich, Allan T.; Edwards, Brent W.
Osteoporosis is a widespread bone disease where bones become less dense (low bone mass) and the internal structure of bone tissue breaks down, leading to weaker bones that are more prone to fracture. Distal radius fractures (Colles’ type fracture) are one of the most common types of fractures to occur. Loading is generally assumed to be purely axial, with forces aligned with the length of the distal radius when simulating a fall onto the outstretched hand. However, the mechanics of distal radius fractures are not well understood and contributions to fracture from bending caused from off-axis loading may contribute to fractures more than previously considered. The objectives of this thesis are 1) to investigate bone strain at the distal radius by creating a subject-specific two-dimensional (2D) finite element (FE) model to evaluate tensile and compressive strains on the palmar and dorsal surfaces during off-axis loading, and 2) to evaluate experimental bone strain distributions during off-axis loading of cadaveric wrist specimens to failure. Two studies were conducted to evaluate the loading characteristics of the distal radius under off-axis conditions. First a 2D ANSYS Finite Element model was created from the sagittal segmented data of one cadaveric specimen. Off-axis loading resulting from palmar load transferred through the trapezium, scaphoid/lunate bones and balanced by the palmar ligaments created a moment around the centerline of the distal radius near the common fracture location. Surface strain measurements around the common fracture site were measured from the model during off-axis loading. The second study completed two testing methods: 1) non-destructive testing measuring surface strain values during a simulated fall onto the outstretched hand at four angles (0°, 15°, 22.5°, and 30°) under dorsiflexion, 2) destructive testing at 15° attempting to replicate Colles-type fractures experienced during a fall onto the outstretched hand. Inclusion of off-axis loading in the first study resulted in Tension to Compression (T:C) ratios ranging from 0.55 to 0.71 near the common fracture site from the ANSYS finite element simulation. Peak principal compressive strain found was 6,212µε and peak tensile principal strain was 4,397µε. The palmar surface experiences a dominant tensile strain. As expected, the ligament representing radiocarpal ligaments between the distal radius and carpal bones is under tensile force. Load sensitivity was found for five different load locations. Mechanical testing in the second study involved loading each specimen, resulting in the applied force being directed approximately at the location of the scaphoid and trapezium carpal bones with the hand in dorsiflexion. The tensile (palmar) and compressive (dorsal) strain for each loading angle (0º, 15º, 22.5º, and 30º) were found to indicate a transition from dominant compressive (dorsal) strain to larger in magnitude tensile (palmar) strain with increasing angulation. With 0° angulation, primary compressive loading was found; significantly larger tensile strains were found under increases in dorsal angulation resulting in an increase in bending moments experienced during loads. Lateral strain was compressive but smaller in magnitude than either dorsal or palmar results. Purely axial (0°) loading had a decrease in T:C ratio as more force was applied: 0.44 to 0.28. For further off-axis loading at 22.5° and 30°, T:C ratios were 0.51 to 0.52 and 0.57 to 0.58 respectively. Fracture testing resulted in two transverse fractures of the distal radius. Failure loads were 822 N and 375 N. The third tested specimen did not fracture, but rather experienced a dislocation of the radiocarpal joint. For the two failed specimens, distal radius fracture patterns were consistent with the classification of Colles’ type fracture, with fracture in the transverse metaphyseal region (25-40mm proximal to carpal joint), dorsal angulation of the fragment and palmar tilt.
Federated Learning and Meta-Learning for Medical Image Classification: Effective Aggregation Techniques and Adaptive Learning Rate Approaches
(2024-08-23) Hossen, Nazmul; Xiaodong, Liang; Wahid, Khan
Computer-aided diagnosis (CAD) has the potential to revolutionize medical diagnosis through advanced machine learning (ML) algorithms. However, the efficacy of CAD systems relies heavily on extensive, diverse, and annotated datasets for robust training. This dissertation proposes a multifaceted strategy to address data scarcity, privacy concerns, and diverse data distribution across healthcare institutions by harnessing two major types of learning methods: federated learning (FL) and model-agnostic meta-learning (MAML). In the first learning method, FL enables CAD systems to train on diverse data across multiple institutions, overcoming individual dataset limitations. However, data heterogeneity (e.g., due to non-independent and identically distributed data) among clients causes client model divergence, making it challenging to achieve convergence during model aggregation. To address these challenges, we propose different aggregation techniques: randomsampling federated maximum (FedRSMax), random-sampling federated median (FedRSMed), and federated rank-based client selection aggregation (FedRSA). In the second learning method, MAML has the potential to facilitate swift adaptation to varying medical imaging datasets, effectively navigating discrepancies in imaging protocols and disease presentations. However, MAML struggles with fixed learning rates, limiting adaptation to varying task complexities. To address this challenge, we propose a task similarity-driven meta-adaptive learning rate mechanism. Overall, this research pursues a two-fold strategy: (1) to develop an efficient aggregation technique for medical image classification using FL; and (2) to employ MAML within a few-shot learning framework, optimizing adaptation to datasets with limited samples. The proposed methodologies are evaluated using a comprehensive set of performance metrics, including accuracy, convergence rate, and adaptation loss. By integrating these cutting-edge techniques, this dissertation advances the frontier of CAD systems, paving the way for more accurate, adaptable, and scalable solutions in medical image analysis.
Cannabis Use in Knee Osteoarthritis
(2024-08-23) Kizlyk, Kelly; Mansell, Holly; Yakiwchuk, Erin; Alcorn, Jane; Gjevre, Regina; Fitzcharles, Mary-Ann
The abstract of this item is unavailable due to an embargo.
Braid groups and Baxter polynomials
(2024-08-23) Friesen, Noah; Weekes, Alex; Wendlandt, Curtis; Weekes, Alex; Wendlandt, Curtis; Rayan, Steven; Wang, Jiun-Chau
It is well known that the braid group of a simple Lie algebra acts on its integrable representations via products of exponentials of its Chevalley generators. In particular, the Yangian is an integrable representation, so there is an action of the braid group on this space. We show that modifying this action induces an action of the braid group on a certain commutative subalgebra of the Yangian by Hopf algebra automorphisms. By dualizing this modified action, we recover an action of the braid group on tuples of rational functions defined in the work of Y. Tan. Using this dual action, we prove a conjecture of S. Gautam and C. Wendlandt that the two sufficient conditions for the tensor product of finite-dimensional irreducible representations of the Yangian to be cyclic are identical. One of these conditions involves the aforementioned action of the braid group on rational functions, and the other involves roots of the Baxter polynomials, which have many interesting properties and ties to mathematical physics.
Coupling a Hydraulic Model with the Cold Regions Hydrological Modelling Platform to Predict the Spatial Extent of Localized Flooding
(2024-08-22) Khatibi Kheibari, Amir; Kells, James; Helgason, Warren; Ireson, Andrew
The abstract of this item is unavailable due to an embargo.

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