University of Saskatchewan Research Archive
Not a member yet
14369 research outputs found
Sort by
SPATIAL AND FEATURE ANALYSIS OF THE WHITING SLOUGH SITE (ElNs-10): AN AVONLEA PROCESSING SITE IN SOUTH-CENTRAL SASKATCHEWAN
Get PDFThis thesis discusses the overall function and description of features and activity areas for the Whiting Slough Site (ElNs-10). This is done by investigating the spatial relationships between various artifact groups to identify localized densities of activity. These artifact densities were then analyzed and interpreted to be specific activity areas within the larger processing events taking place at the site. The features found at the site were separated into various feature classes based on their attributes. In addition, the spatial relationship of these features to each other was assessed. The spatial analysis of the site employed ESRI’s ArcMap to assess and compare artifact density of different artifact groups. This facilitated identification of site function as well as identifying the specific areas of distinct processing events.
As a result of this project the site was identified as an Avonlea processing site. However, this processing site has additional features that have not previously been seen in other Avonlea processing sites. There are a total of 43 different features that were discovered during excavation of the site. These are divided into four different feature types: bone-filled pits (39), hearths (2), a canid burial (1) and a soil stain (1). These features are accompanied by an additional seven potential bone-filled pits that were discovered during construction monitoring following excavation. These individual features combine to form two distinct ovoid feature groups that run parallel to one another. Potentially two more of these feature groups were partially unearthed during excavation and construction monitoring. These features are interpreted to be part of a drying rack. It is hypothesized within this thesis that these bone-filled pit features were created to counteract the difficulties with trying to anchor heavy loads of meat into the very loose sandy sediment that is present at the site.
The Whiting Slough Site appears to be much different than any other Avonlea processing sites. The uniqueness of these features as well as the large amounts of artifacts, both faunal and lithic, make the Whiting Slough Site an interesting and important site for understanding the subsistence strategies and versatility of people within the Avonlea Phase
Integrating residual herbicides with cultural and mechanical weed control in faba bean (Vicia faba L.)
Get PDFHerbicide resistance is becoming an increasing problem worldwide, one that is threatening global food production. Frequent use of herbicides with high efficacy has led to strong selection pressure for the development of herbicide resistant weed species. Faba bean (Vicia faba L.) is an emerging crop in western Canada. To date, there is very limited research that contains several integrated weed management strategies together to mitigate weed pressures. Field trials were conducted near Saskatoon, Floral and Melfort, Saskatchewan to address this gap. The first study in this research aimed to determine the optimal combination of pre-emergence (PRE), residual herbicides and crop seeding rate to reduce the number of weeds exposed to a post emergent herbicide application. Weed control was improved by the addition of pyroxasulfone+sulfentrazone into a tank mix with glyphosate, but the greatest weed control was with when a PRE herbicide was combined with POST emergence application of imazamox+bentazon. Although no interaction was observed between herbicide and seeding rate, higher seeding rates tended to improve weed control and crop yield. The optimal seeding rate needed to reach the highest yield varied for each herbicide treatment. The objective of the second study was to determine if high or medium intensities of integrated weed management strategies (IWM), combined with a PRE herbicide with residual characteristics, could eliminate the need for a post emergence herbicide application. The best weed control was achieved with medium to high levels of intensity of integrated weed management strategies. Weed control generally did not differ among herbicides, regardless of the duration of the residual period. The highest crop yield and seed size was also observed in the medium to high IWM treatments. Herbicide did not affect crop yield or seed size. Based on the results in these studies, growers should seed a faba bean crop in early May or late April, depending on environment, with an increased seeding rate (50-75 seeds m-2) and a narrower row spacing (<25 cm). Furthermore, using a pre-emergence herbicide such as pyroxasulfone+sulfentrazone, saflufenacil, or flumioxazin will help to further reduce early season weed pressure, while reducing the risk for developing herbicide resistant weeds. In addition, near perfect weed control was achieved with an effective PRE herbicide coupled with a high IWM intensity. This demonstrates that it is indeed possible to achieve both excellent weed control and good crop production without the use of an in-crop herbicide
Mechanisms of Seed Discrimination and Selective Seed Foraging in Carabid Weed Seed Predators
Get PDFGround (carabid) beetles (Coleoptera: Carabidae) are among the most prevalent biological agents in temperate agroecosystems, with numerous species functioning as predators of both insect pests and weed seeds. Several carabid species are omnivorous, and the diversity and complexity of their feeding habits makes it difficult to predict the magnitude of population suppression they impose on pest and weed species. Thus, it remains unclear why omnivorous carabid beetles choose to feed on seed species when alternative food sources are available. It was first thought that seed feeding in carabids was driven by chance alone and hence, take place upon random encounter. Recent lines of evidence show that carabid predators can be quite choosy or selective about the seeds they consume when seeds of different species are offered in laboratory or field feeding experiments. Seed feeding habits in carabids thus seem driven by active seed discrimination and selection behaviors. Yet, little is known about the sensory, behavioral, nutritional, and biophysical mechanisms that underlie seed preferences in carabid seed predators.
In this thesis I explore the feeding ecology of omnivorous carabid species and describe aspects of the sensory, behavioral, nutritional, and biophysical ecology involved in their seed feeding habits. Multiple-choice feeding bioassays coupled with sensory manipulations of carabid predators showed that carabids rely on their olfactory system to detect seeds of different species and identify the suitable seed species among them. Seed choice was driven by the perception of long chain volatile chemicals derived from the epicuticular lipids located on the seed coat surface. Seed surface volatiles seemed to encode information about the nutritional quality of seed species, especially their fatty acid content. Experiments with synthetic diets showed that omnivorous carabids potentially seek seed consumption to overcome the scarcity of some lipids in their diets.
Carabids most likely choose seed species based on desirable lipid content if the physical properties of seed species in the environment pose no challenges to efficient seed handling. However, if physical seed traits such as mass or size are highly variable among seed species, seed handling costs are likely to vary widely among seed species and thus, constrain the active selection of nutritious seeds. Carabids would more preferably select seed species that are easier to handle in such a case, irrespective of their nutritional quality. The findings of this thesis bridge important knowledge gaps in the seed feeding ecology of carabid species as the sensory basis of seed perception and discrimination is elucidated, and some of the key factors that render seed of certain species more vulnerable to elevated carabid attacks are identified
Dramatic Indigenization: An Investigation and Analysis of Indigenizing Saskatchewan Drama Curriculum
Get PDFA current barrier to Indigenizing the current Canadian school system is the lack of knowledge by educators of how to teach using Indigenous ways of knowing in a meaningful and authentic way. The research I have conducted proposes that an already existing curriculum can be Indigenized by taking the established learning outcomes and meeting them using Indigenous ways of knowing and learning. Using the Saskatchewan drama curricula this research first analyzes the currently used drama curriculum in Saskatchewan, and determines how and if it currently teaches with an Indigenous paradigm in mind. This research then develops the ATS (Action/Text/Subtext) framework that determines how to conceptualize drama using Indigenous ways of knowing across grades 10-12 so that the same curriculum outcomes as before are maintained, but are taught through Indigenous paradigm and using Indigenous ways of knowing. The hope of this research is to focus on creating a paradigm shift that moves from the colonial paradigm in which the current drama curriculum has been created, into a paradigm that utilizes Indigenous ways of knowing in order to Indigenize how curriculum is understood and taught within schools
Development of innovative bioengineering approaches for the regeneration of dental enamel
Get PDFDental enamel is the hard tissue that covers the tooth crown that is incapable of endogenous regeneration, once damaged, due to the loss of enamel secreting cells (i.e., ameloblast) following the tooth eruption. The current treatment options, including artificial filling materials, are of temporary solutions. This greatly raises the need of approaches to regenerate enamel, which, however, remains unachievable nowadays. To address this emerging need, this thesis aimed to develop novel bioengineering approaches for the regeneration of enamel tissue. The specific objectives are to develop (1) lipid-based gene delivery systems for Tbx1 encoding genes to dental epithelial cell line, HAT-7 cells, (2) an ionically cross-linkable bioink composed of alginate and carboxymethyl chitosan for bioprinting of HAT-7 cells, (3) a covalently cross-linkable hydrogel consisting of oxidized alginate and carboxymethyl chitosan with injectability and self-healing properties as a cell carrier to incorporate HAT-7 cells, for enamel formation in vitro.
The first objective was to prepare and characterize a non-viral gene delivery system for the transfer of plasmid DNA encoding Tbx1. First, we prepared and characterized lipid-based nanoparticles that were based on two different cationic lipids: glycyl-lysine-substituted gemini surfactants with the 16-carbon tail and 1,2-dioleoyl-3-trimethylammonium-propane with three varying the ratios of cationic lipid nitrogen to pDNA phosphate (N/P ratios: 2.5, 5 and 10). The physicochemical properties and biological activities of these nanoparticles were examined in terms of particle size and zeta potential, morphology, DNA protection, cytotoxicity, and gene expression, with the results illustrating that the gemini surfactant-based nanaoparticles with the N/P ratio of 5 is the optimal formulation among those examined. Then, HAT-7 was transfected with the optimal formulation and cultured in 2D and 3D, photo-cross linkable gelatin methacrylate hydrogels, culture systems; followed by the assessment of ameloblast differentiation and enamel formation by evaluating the expression of ameloblast markers and by using mineralization assays. Results showed that the HAT-7 cells transfected with Tbx1 gene were able to robustly express secretory and maturation ameloblast markers, have higher calcium deposition, and form more extensive mineralized nodules compared to control cells.
The second objective was to develop a bioink consisting of alginate and carboxymethyl chitosan for the fabrication of 3D HAT-7 cell-laden constructs by using three-dimensional extrusion bioprinting for enamel tissue engineering applications. Alginate and carboxymethyl chitosan were mixed at three different mixture ratios (2-4, 3-3- and 4-2) and printed as porous scaffolds while being ionically crosslinked in calcium chloride bath (100 mM). Then, the physico-mechanical and biological properties of the 3D printed scaffolds were characterized in terms of structural features, swelling and degradation behavior, mechanical properties, cell viability, cell morphology, and mineralization. Results indicated that alginate 4%-carboxymethyl chitosan 2% hydrogels showed higher viscosity, slower degradation rate, lower swelling ability and higher compressive mechanical properties. HAT-7 cells showed a high percentage of viability, maintained their morphology and secreted alkaline phosphatase.
The third objective was to develop injectable self-healing hydrogels based on oxidized alginate and carboxymethyl chitosan for the use as a carrier of the dental epithelial stem cells for enamel regeneration applications. First, alginate was modified through oxidation reaction and chemically characterized. Then, oxidized alginate and carboxymethyl chitosan were mixed at three varying weight ratios (4:1, 3:1, 2:1) and in situ crosslinking occurred through Schiff base reactions, which was confirmed by chemical characterization. The physico-chemical and biological properties of the hydrogels were assessed in terms of gelation time, swelling ratio, structural, injectability, self-healing, antibacterial properties, cell morphology and viability, mineral deposition. The results indicated that hydrogels with the higher weight ratio of oxidized alginate had faster gelation time and lower swelling ability. Hydrogels formed highly porous structures and showed injectability and self-healing abilities, as well as antibacterial properties against two cariogenic bacteria. HAT-7 cells were able to maintain a high cell viability, without being affected by injection pressure, and could maintain their morphology, deposit minerals and secrete alkaline phosphatase.
Taken together, this thesis presents the development of methods for bio-enamel formation in vitro based on gene therapy and tissue engineering principles. The combination of optimized lipid-based system for T-box1 gene delivery and the developed hydrogel-based scaffolds may provide a foundation to develop the optimal conditions for enamel regeneration in vitro and in vivo
The Impact of Cover Cropping on Soil Nitrogen Availability, Crop Nitrogen Use, and Nitrous Oxide Emissions in a Prairie Potato—Grain Crop Rotation
Get PDFIn prairie regions of Canada, growers are beginning to adopt cover cropping. Yet several questions remain unanswered on the viability, impact, and benefits associated with cover cropping in a short growing season region like the prairies. To address this gap, a four-year fully phased crop rotation trial consisting of wheat (Triticum aestivum)- canola (Brassica napus)- potato (Solanum tuberosum)- pea (Pisum sativum) grown with vs. without shoulder-season cover crops, red clover (Trifolium pratense), berseem clover/oat (Trifolium alexandrinum/Avena sativa), rye (Secale cereale), and mustard/tillage radish (Brassica juncea/Raphanus sativus) respectively, was set up in Saskatoon to determine cover crop influence on N availability, crop nitrogen use efficiency (NUE), and N2O emissions. A short rotation (wheat-canola) and a perennial alfalfa were included as treatment checks. Results showed that cover crops are viable, but success depends on species, management, and weather conditions. It was evident that cover crops influenced N cycling during the non-growing season (in the fall or spring). Cover crops had potential to reduce post-season N losses through plant N uptake and subsequent N release through mineralization. However, there was no cover crop effect on main crop yields and NUEs. When cover crop impact on N2O emissions were evaluated, several trends pointed towards higher N2O emissions with vs. without cover crops especially if a legume appeared in the phase studied. However, there were exceptions where cover crops significantly increased emissions. Emission events were observed post-fertilization and at spring thaw for all crop rotations. The growing season, post-harvest and spring thaw contributed 51, 7 and 42%, respectively to the cumulative annual emissions. Overall, it can be concluded that N dynamics were not markedly influenced by cover crops in the crop rotations studied. Longer-term studies are recommended to detect any possible impacts on N cycling, as cover crop effects may gradually build overtime. Future research should investigate methods of supporting rapid cover crop establishment and biomass accumulation (i.e., cold hardy varieties, early-seeding or under-seeding techniques). To sufficiently benefit main crop NUEs and reduce the risk of N losses, cover crop management may need to be bundled with other practices such as N fertilizer rate adjustments
kihteyhayak pihkswestamawnan: Wisdom Keepers Will Speak for Us
Get PDFChris Scribe’s dissertation is premised around Indigenous leadership and learning. He worked with the University of Saskatchewan Human Ethics board to redesign what constitutes relational ethics and sources of knowledge for what traditionally has constituted a “literature review.” His work is premised on the knowledge of traditional Elders and how that knowledge is “owned”, “(re)-presented” and granted source credit.
Chris’ dissertation is framed through a creative Indigenous cosmology that privileges orality, experiential learning, and artistic expression. Rather than offering a written work that privileges the language of the colonizer, his work is based in an oral and video docu-story that incorporates cultural expression and symbology. In this journey, Chris articulates through dance, artistic expression, and kinship the ways in which ancestral knowledge of leadership and learning is enacted, along with how he positions himself in his responsibilities to the ancestors, to the land, and to this knowledge.
His work maintains academic standards of rigour but is organized in a non-traditional format. Throughout the video, he situates himself in his social location, and also his ancestral territorial locations, from where he explains the impetus for his work on Indigenous leadership and education, its significance, and his role and space. He then explains the Indigenous cosmology within which he is working, describing it through the use of a framework that he has created using Indigenous symbolism, life cycle, and relationships to learning and leading. He discusses the ethical journey he has travelled to incorporate the appropriate protocols in which he has engaged (through the University of Saskatchewan and with Knowledge Keepers) in order to access and share knowledge from the Elders to whom he has spoken on issues of leadership and learning (that also informs his conceptualization). He speaks about how he represents his learnings on educational leadership and his role (and others’ responsibilities) for using this knowledge to inform leadership practice. The final portion of the docu-story includes the overlaying of Indigenous leadership story-work over the “text” of a treaty document in order to represent the juxtapositions of understandings at play in the relationship between colonizers and Indigenous peoples that has impacted constructions of learning and leadership for Indigenous peoples. The final analysis culminates in an “accounting” of his research and learning on a buffalo robe
REALISTIC CADAVER MECHANICAL TESTING & QUANTITATIVE MAGNETIC RESONANCE IMAGING FOR EVALUATING KNEES THROUGHOUT WALKING
Get PDFIntroduction: Knees are subjected to daily physical activities, injuries and diseases, such as osteoarthritis (OA). Such complications represent significant costs (billions and thousands of USD/year for countries and individuals, respectively). Moreover, there is no OA cure and its risk factors (obesity, malalignment and injury) affect joints’ mechanical loading. Thus, knees must be studied under realistic loading conditions. Unfortunately, due to joints’ complexity (geometry, mechanical properties and loading), current experimental methods seldom achieve this. Quantitative magnetic resonance imaging (qMRI) potentially offers a non-invasive evaluation of tissue structure, biochemistry and mechanics, thereby facilitating injury or disease tracking if links between these properties and imaging outcomes were well established. However, the connections between tissue health and mechanical properties remain unclear, as is the relation between tissue- and joint-level biomechanics.
Objective: Determine if tissue structure and joint function are related in whole cadaver knees under physiologically realistic loading conditions applied via a novel MRI-safe loading device.
Methods: A novel MRI-safe knee loading device was designed, built and its repeatability assessed. Physiologic loading conditions (simulating walking) suitable for mechanical tests were determined via musculoskeletal (MSK) modelling, verified and validated against published data, and applied to a cadaver knee. To measure tibio- and patello-femoral (T-F and P-F) contact responses, a pressure sensing system was used in conjunction with the instrumented loading device. Then, to search for T2 relaxation-deformation associations, tibial and patellar cartilage deformations and T2 relaxation responses of other six ex-vivo knees subjected to axial compression (simulating standing) were measured and correlation analyses performed.
Results & Discussion: The MRI-safe loading system developed was able to simulate healthy or pathologic gait with adequate repeatability (e.g., 1.23 to 2.91 CV% for compression, comparable to existing simulators), leading to generally consistent contact responses in agreement with published experimental and finite element studies. Cartilage thickness and T2 relaxation time magnitudes measured fell within expected values, while their loading-induced changes agreed with previous studies but exhibited larger variability. Moreover, a moderate negative correlation (r = -0.402, p = 0.019) was found between unloaded tibial cartilage thickness and T2 relaxation time, which may be linked to cartilage composition (relating collagen fibers and water content)
Soil carbon and nitrogen dynamics in rejuvenated grazed pasture systems sod-seeded with non-bloat legumes
No full textThe abstract of this item is unavailable due to an embargo
Premature and Avoidable Mortality by Neighbourhood Income in Urban Canada
Get PDFBackground: Canadians are among the healthiest people in the world. Policy initiatives, such as implementing universal healthcare, have been employed to distribute this health equally among different groups of people in the country. Yet, health inequalities still exist and, in some cases, are growing across Canada. A key step to address health inequalities is to improve the measurement, monitoring, and reporting of social determinants of health, population health status, and the extent of health disparities.
Purpose: The underlying purpose of this study is to provide evidence on health inequalities and how these inequalities are related to income disparities in urban Canada, at the municipal, provincial, and national levels, to empower policymakers in evidence-based decision-making to implement policies to tackle health disparity in Canada.
Methods: This study was conducted in two phases. The first phase was a scoping review on application of the concept 'avoidable mortality' in socioeconomic-related health inequality research. The second phase of this study was a retrospective population-based analysis, conducted in two parts; first, the Canadian Vital Statistics - Death Database (CVSD) from 2011 to 2015 and Canadian Censuses 2011 and 2016 were used to calculate all-cause, premature, avoidable, preventable, and treatable mortality rates at municipal, provincial, and national levels; then, the National Household Survey (NHS) 2011 was used to measure income inequality in mortality by calculating concentration index, at municipal, provincial, and national levels.
Results: Findings spanning the period of 2011 to 2015 suggest that overall, income inequality in mortality exists at every level of geography in Canada. This study found a higher inequality in preventable mortality as compared to the inequality in all-cause, premature, avoidable, and treatable mortality, at all geographic levels in Canada. Another finding of this study shows that, at the provincial level, Saskatchewan was the only province with an inequality higher than national level inequality in all the mortality indicators. At the Census Metropolitan Area (CMA) level, Winnipeg was the most unequal CMA in premature, avoidable, preventable, and treatable mortality indicators over the study period.
Conclusion: Findings of this study highlight the need for an improvement in policies whose primary purpose is prevention, to curb the preventive mortality burden and reduce disparity in mortality. Additionally, the geographic variation in inequality found in this study points to the need for future research on identifying the factors leading to this difference in inequality across jurisdictions