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Graduate Theses and Dissertations

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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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    WINTER AND MOLECULAR ECOLOGY OF THE AMERICAN DOG TICK, Dermacentor variabilis, ON THE CANADIAN PRAIRIES
    (2024-07-23) Yunik, Matthew E.M.; Chilton, Neil; Benson, James; Dergousoff, Shaun; Hill, Janet; Todd, Chris; Wilson, Ken; Trout Fryxell, Rebecca
    The range of the American dog tick, Dermacentor variabilis, is expanding northwards into the Boreal transition ecoregion, where ticks experience colder winter temperatures. This thesis examined if adult ticks in a recently established population (Lizard Lake Community Pasture [LLCP]) near the edge of the species range survive over winter, have greater cold-hardiness than ticks in other populations, and if there are differences in the bacteria within in their microbiomes that may enhance overwinter survival. The results showed that the overwinter survivorship in outdoor enclosures was lower at LLCP than the established population at Sandy Hook. Also, significantly more females survived than males. Although the supercooling points (SCP = the temperature at which ticks freeze) of females did not differ from those of males, ticks from Sandy Hook had a colder SCP than ticks from LLCP, suggesting that adults at Sandy Hook are better adapted to deal with the environmental conditions they experience than those at LLCP. Also, the SCPs of lab-reared adults had a unimodal distribution, whereas those of questing adults in the field in early spring was bimodal, the later indicating the existence of two adult cohorts. By summer, there was a normal distribution of SCP values from questing ticks, suggesting a loss of some adults from the population. Therefore, environmental factors have an important impact on the SCP and off-host survival of ticks. Interestingly, bacteria present in the microbiomes of adults from LLCP during late summer were not different from adults that survived overwintering based on next-generation sequencing data. However, quantitative PCR analyses revealed that Francisella-like endosymbionts (FLEs), which are obligate tick mutualists, were more abundant in female ticks than males, especially for individuals that overwintered. Also, ticks infected with Rickettsia montanensis had a greater relative abundance of Rickettsia than FLEs, and a lower FLE abundance than ticks not infected R. montanensis, suggesting a negative interaction between these bacteria. The knowledge gained from this study has important implications for predicting range expansion by D. variabilis, and provides the foundation for future studies on the physiology and molecular ecology of the American dog tick.
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    Wildfire Severity, Recovery, and Grazing Management in the Dry-Mixed Grasslands of Southern Alberta and Saskatchewan
    (2024-07-23) Grover, Sera Anne; Lamb, Eric; Lardner, Bart; Carlyle, Cam; Prager, Sean; Guo, Xulin
    In the fall of 2017 two wildfires in southern Alberta and Saskatchewan burned approximately 28 000 hectares under extreme weather conditions. These fires completely burned over many ranches, and raise many questions, including how the fire severity and recovery are affected by topographic and soil gradients, and how biomass production and plant species diversity recover including the role of grazing management decisions in recovery. Fire severity in relation to slope, aspect, and available fuel was assessed utilizing the bare soil index (BSI) by calculating the difference between the amount of soil exposure from pre-fire to immediately after the fires. Recovery of biomass production in relation to fire severity, land capabilities, potential land productivity, and solar heat load was assessed utilizing the normalized difference vegetation index (NDVI) to compare post-fire vegetative greenness to that of baseline pre-fire peak biomass greenness. Recovery of live biomass and species metrics with and without fire and grazing were assessed using a factorial randomized complete block design. I found that fire severity increased with increased slope and decreased vegetative greenness. Fire severity was highest in areas with slopes steeper than 15 and aspects that were within the 45 flanks of the dominate wind direction. Recovery of biomass was best in areas of moderate fire severity and solar heat load. The complete recovery of live biomass was noted by year three of the study and the complete recovery of litter was not noted by year five. Grazing has no significant effect on recovery of either biomass or species metrics.
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    Septic arthritis in western Canadian feedlot cattle: a comparison of antimicrobial treatment options and a description of the bacterial communities present in infected joints
    (2024-07-23) Warr, Brian Nelson; Jelinski, Murray; Ruzzini, Tony; Schwartzkopf-Genswein, Karen; McAllister, Tim; Harding, John; Erickson, Nathan
    Septic arthritis (SA) presents health, welfare, and production concerns in western Canadian feedlots. Septic arthritis has the highest case fatality rate of lameness causes and little information exists on treatment options. Mycoplasmopsis bovis is often the primary etiological agent of SA in feedlot cattle and H. somni has also been implicated. Furthermore, animals with SA often have concurrent chronic pneumonia. As a result, SA treatment protocols commonly recommend parenteral administration of antibiotics that have label claims for bovine respiratory disease (BRD) but with little efficacy information available for treatment of SA. The objectives of this two-year investigation were to 1) compare the health outcomes of three commonly administered antibiotics for the treatment of SA and 2) determine the microbiota of synovial fluid collected from SA joints. The treatment study consisted of trained pen riders identifying SA cases from the fall-placed calf population over a two-year period at four commercial feedlots. Cases were randomly allocated to three antibiotic treatments: florfenicol (FFN), oxytetracycline (OXY), and tulathromycin (TUL). The health outcomes monitored to 90 d post allocation included SA relapse treatments (first and second), BRD treatment, infectious mortality (BRD, H. somni, SA), and SA only mortality. Additional outcomes were early shipment for salvage slaughter (railer) and the sum of infectious mortality events and railer events (total fall out). In order to describe the microbiota of synovial fluid from SA cases, synovial fluid samples (n = 137) were collected over the same two-year period in the fall placed calf population at 11 commercial feedlots. The samples were collected via arthrocentesis from joints with and without SA and from antemortem and postmortem specimens. After collection, the samples were frozen at -20°C and then -80°C until DNA extraction process was completed. Samples underwent 16S rRNA gene sequencing using an Illumina platform and analysed using DADA2, QIIME2R, and the R-package. Amplicon sequence variants (ASVs) were based on 99% similarity and taxonomy was assigned using the SILVA reference database. Samples with less than 20,000 reads were omitted from the final analysis. In total, 251 eligible cases were allocated to the treatment comparison and no differences (P > 0.05) were noted for the morbidity outcomes of first and second SA relapse and BRD. Likewise, no differences (P > 0.05) were noted in the mortality outcomes, railer events, or total fallout. Time to event analysis was conducted with no differences (P > 0.05) noted for any of the health outcomes. From the original 137 synovial fluid samples, 66 met technical criteria to be included in the final analysis. Mycoplasmatota accounted for 96.6% of the phyla abundance and Mycoplasmopsis accounted for 94.8% of the abundance at the genus level. Samples from SA cases were noted to have a higher abundance of Mycoplasmopsis (P=0.033) and a lower Shannon diversity index compared to controls (P=0.018). Postmortem samples had a higher abundance of Mycoplasmopsis (P = 0.015) and a lower Shannon diversity index than antemortem samples (P = 0.001). Only 8.5% of the ASVs assigned to Mycoplasmopsis were assigned to the species level with M. alkalescens and M. wenyonii present in 10 and 2 samples, respectively. Histophilus did not rank in the top 15 genera found and the Pasteurellaceae family (of which Histophilus belongs) only accounted for 1% of ASV assignments. The lack of differences in health outcomes by treatment indicate that there is no economic advantage to using a particular treatment; the most cost effective product would be the least expensive to purchase. A study limitation was the lack of production performance data, which may have revealed differences by treatment. The lack of difference observed in the three antimicrobial products also introduces a question of antimicrobial efficacy for SA, it is possible that the products were equally ineffective. Conclusions from the microbiota study of joints with SA in the western Canadian feedlots are that Mycoplasmopsis is the predominant genera. Also of interest was that Histophilus was not found in the top 15 genera from the samples in this study. The lack of Histophilus is surprising because it has been considered an etiological agent for feedlot SA cases. The presence of M. alkalescens and M. wenyonii in SA joints suggest further research is needed to understand the impact of Mycoplasmopsis species other than M. bovis in the role of SA.
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    Assessment of Precision Irrigation on Potatoes in Southern Alberta
    (2024-07-23) Harding, Adele; Schoenau, Jeff; Helgason, Warren; Si, Bing; Appels, Willemijn
    The abstract of this item is unavailable due to an embargo.
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    Development, Analysis and Evaluation of the LIFE Prototype Instrument
    (2024-07-23) Runge, Ethan; Bourassa, Adam; Degenstein, Doug; Toohey, Matthew; Steele, Tom; Milne, Doug; Smolyakov, Andrei; Bradley, Michael; Sica, Robert
    There exists in the upper troposphere/lower stratosphere (UTLS) region of the atmosphere an identified observational gap in measurements, leading to large uncertainties in climate models. This region is crucial to understanding the climate of our planet due to the strong effect of dynamic, chemical and radiative processes within. In recent decades, infrared Fourier Transform Spectrometry has been identified as, and demonstrated to be, a prime candidate for remote sensing techniques with the necessary spectral, spatial and temporal resolution to combat the present scarcity of these critical observations through instruments such as MIPAS and GLORIA. The Limb Imaging Fourier Transform Spectrometer Experiment (LIFE) aims to build upon the legacy of these instruments with a design comprised of commercially available components and with greatly reduced complexity and cooling requirements, with minimal impact to measurement quality. This prototype instrument primarily targets the important greenhouse gases H$_2$O, O$_3$, CH$_4$ and N$_2$O and seeks to obtain vertical trace gas profiles for each by taking infrared measurements in the 700 to 1400 cm$^{-1}$ wavenumber range from a balloon-based platform. The design, characterization and calibration of the original instrument is the subject of a publication included in this work that details the instrument concept and operation, design principles and initial results from a 2019 demonstration flight from Timmins, Ontario. Additional aspects of the instrument design such as practical considerations, optical alignment challenges, and supporting technologies and hardware are discussed as well. Analysis of the measurements taken during the demonstration flight indicate a completion of primary scientific goals through the determination of vertical trace gas profiles for each of the target species and HNO$_3$ additionally, which was the subject of a second publication. Though comparison of the LIFE vertical trace gas profiles with credible trace gas profiles from the ACE and MLS instruments confirmed the results, a number of weaknesses and areas of improvement for successor instruments are detailed, which will allow further closing of the observational gap and ultimately contribute to a better understanding of the UTLS and the climate of the Earth.
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    Detoxification of DON Contaminated Wheat by Fractional Pneumatic Separation, Near-Infrared Transmittance (BoMill), and Gaseous Ozone, and the Effects of Treated Grain on Broiler Chickens.
    (2024-07-23) Taylor, Meghan Elizabeth Josie; Newkirk, Rex; Adewole, Deborah; Beaulieu, Denise; Brook, Ryan; Acharya, Bishnu
    The mycotoxin deoxynivalenol (DON) caused by Fusarium spp. in cereal grains is a concern to the livestock industry, Current practices involve blending with clean grain to reduce overall DON content, but issues arise when clean grain has limited availability. These experiments were designed to determine: (1) if low DON wheat could be recovered from high DON wheat using specialized instruments; (2) the improvement of low DON grain recovery using two instruments in sequence and performance effects of sorted grain fed to broiler chickens; (3) the efficacy of gaseous ozone to reduce DON content in contaminated grains. The BoMill IQ (BoMill; BoMill AB, Sweden), a near infrared transmittance spectroscopy (NIT) single kernel sorter, was used with the Fusarium calibration to sort DON contaminated grain, as well as a GCS-200 grain cleaner (Grain Cleaning, LLC, MN, USA). In the first study, the BoMill was used to sort DON contaminated wheat and determine optimal calibration (Protein or Fusarium) and settings (HVK; hard vitreous kernel) to sort into eight fractions total, six sortable fractions with two unsortable fractions, and determine grain recovery under 5mg/kg DON of different wheats with different initial DON concentration. Experimental design was a CRD with four replications, data analyzed using least squares regression. The Fusarium calibration HHVK setting had 50.3% (P = 0.015), 29.0% (P = 0.001), and 1.8mg/kg (P = 0.068) recovered low DON wheat, rejection rate, and DON content respectively, which were intermediate to other settings and optimal compared to Protein calibration HVK setting 46.2% (P = 0.005) recovery, 35.6% (P = 0.001) rejection rate, and 1.6mg/kg (P = 0.001) DON content. Grain recovery (P<0.001) and rejection rate (P = 0.001) are dependent on initial DON concentration when sorting different sources of DON contaminated wheat. Using the BoMill technology could be an effective solution for regions with high DON incidence. In the second study a GCS-200 grain cleaner was used to sort and clean DON contaminated wheat by grain density, the intermediate DON content fraction was then sorted using the BoMill with optimal settings from the first study. Sorted and unsorted grain was used to formulate diets with graded amounts of DON for broiler birds to evaluate performance and intestinal morphology. Experimental design for grain sorting was a CRD with four replications. Experimental design for the broiler study was an RCBD with a 2 x 4 +1 factorial with ten replications. Fractional pneumatic separation grain recovery was 52.8, 42.7, and 58.8% with an average DON of 1.7, 1.5, and 1.0 mg/kg for three different initial DON wheats. Sequential sorting increased grain recovery between 10.5 to 19%. Dietary DON did not exceed 3.05 mg/kg. Bird performance and intestinal morphology were not different overall between treatments. In the third study, DON contaminated wheat was treated with gaseous ozone at different moisture contents and temperatures. Grain moisture was adjusted to 10.8, 15 or 20% moisture and grain treated with gaseous ozone for 24 hours at room temperature, then 20% moisture content wheat was temperature adjusted to 2°C or 29°C and treated with gaseous ozone for 24 hours. Statistical analysis was performed with one-way ANOVA using JMP. Increasing grain moisture content improved ozone degradation of DON by 6.7, 20.2, and 38.2% (P = 0.011) for 10.8, 15, and 20% moisture grain respectively. Temperature did not affect DON degradation when grain moisture was 20% (P > 0.10). Ozone can reduce DON content of wheat by 20 to 38% of wheat when grain moisture is above 15%. The key findings of the experiments were that the BoMill NIT Fusarium calibration can effectively sort and remove Fusarium damaged grain creating a fraction with reduced DON content. Sorting DON contaminated grain sequentially using a GCS-200 then BoMill improves grain recovery of low DON wheat. Sorted wheat can be used in broiler feed. Treating wheat with ozone can reduce the DON concentration at higher moisture levels.
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    Effect of yeast-fermentation of canola meal on nutrient digestibility, growth performance and health of Nile tilapia (Oreochromis niloticus) and rainbow trout (Onchorynchus mykiss)
    (2024-07-22) Zhang, Chuyuan; Weber, Lynn; Drew, Murray; Brook, Ryan; Øverland, Margareth; Schwean-Lardner, Karen; Niyogi, Som; Adewole, Deborah; Kumar, Manoj
    The rapid expansion of global aquaculture has intensified the needs for sustainable feed alternatives that can replace traditional marine-derived resources like fishmeal (FM) and fish oil. Currently, the use of fermented plant ingredients (FPIs), especially those through solid-state fermentation, in aquaculture production has been gaining significant interest. FPIs have shown potential to enhance nutrient profiles, reduce anti-nutritional factors (ANFs) and improve digestibility and growth in fish, thereby offering a sustainable solution to the challenges posed by conventional feeds. In the present thesis, a comprehensive meta-analysis was conducted to assess the impact of FPIs on the specific growth rate (SGR) across carnivorous, omnivorous and herbivorous fish species. The results revealed significant disparities in SGR when replacing fishmeal (FM) with FPIs in carnivorous fish (P < 0.05). In contrast, herbivorous, and omnivorous fish demonstrated promising adaptability to FPIs when replacing FM (P > 0.05). Additionally, FPIs resulted in better SGR in all fish species when comparing to their corresponding unfermented raw ingredients (P < 0.05). The nutritional effects of feeding unprocessed canola meal (RCM) and candida utilis-fermented canola meal (CFCM) were explored in two eight weeks trial with Nile tilapia and rainbow trout. After fermentation, the canola meal (CM) showed enhanced amino acid content with reduced anti-nutritional factors (ANFs). The crude protein (CP) digestibility of CFCM was significantly higher in rainbow trout (P < 0.05), while no significant difference was observed in nutrient digestibility Nile tilapia (P > 0.05). Results indicated that, while unprocessed canola meal (RCM) negatively influenced Nile tilapia growth, CFCM could be integrated up to 600 g/kg without any detrimental effects on growth performance. Additionally, rainbow trout displayed improved growth performance when fed CFCM over RCM (P < 0.05). The gene expression of specific cytokines in the distal gut of both fish species fed increasing dietary levels of RCM and FCM, were also examined. Results indicated that CFCM has potential as an alternative protein source when included up to 600 g/kg in diets for tilapia, while rainbow trout exhibited less adverse effects when fed FCM compared to RCM. In conclusion, FPIs, especially CFCM, hold significant promise in aquaculture. This suggests potential sustainable alternatives to FM without compromising fish growth and health.
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    The effects of periodic environmental enrichment at different life stages on the welfare and production of growing pigs
    (2024-07-22) Tillotson, Abigail Irene; Brown, Jennifer; Schwean-Lardner, Karen; Seddon, Yolande; Beaulieu, Denise; Brook, Ryan; Johnson, Anna
    It is known that the welfare of intensively raised pigs is improved when housed in enriched versus barren conditions, however, the interaction between enrichment and different life stages is largely understudied. The current study evaluated the influence of periodic enrichment during different life stages on welfare and production in growing pigs. A total of 240 pigs were housed in either Control (C) or Enriched (E) environments during Early life (0-9 weeks of age). The enrichment used in the current study was loosely crumpled newsprint with an added functional neurosensory liquid solution (Phytozen®). Upon moving to grow-finish (GF) for the remainder of the trial (Late life: 10-21 weeks of age), half of the pigs changed environments while half remained in the original environment resulting in four treatments for this stage: CC, CE, EC and EE. Growth was measured throughout life. Post-mixing aggression was evaluated after weaning and when moving to GF. Tail bites and body lesions were assessed throughout GF. A subsample of pigs was transported to the abattoir and carcass characteristics were analyzed. Statistical analysis of Early and Late life data was done using mixed linear models. Growth was increased with enrichment between 18-21 weeks of age (P=0.011). Post-mixing lesions were reduced in E pigs compared to C at weaning (P<0.001 for front and hind regions). The number and severity of tail bites were reduced with the provision of enrichment throughout life (P=0.077 and 0.032, respectively). Lesions during GF were reduced with the provision of enrichment during Late life (CE and EE < EC and CC; P<0.001 for all body regions). Enrichment provided during Early life resulted in greater carcass weights and lean depth (P=0.040 and P=0.031, respectively). The current study provides evidence that periodic enrichment is an effective way of reducing damaging behaviours throughout life. It was shown that pigs with access to enrichment throughout life had improved welfare and behaviour compared to pigs in all other treatments.
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    Disaster Risk Reduction in the Caribbean: Designing Optimal Policy Mixes
    (2024-05-02) Dureau Sargsyan, Glenna M; Rayner, Jeremy; Coates, Kenneth; Hurlbert, Margot; Noble , Bram; Prytula, Michelle; Mamuji , Aaida
    The abstract of this item is unavailable due to an embargo.
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    The differences in preferences among traditional vs. non-traditional lentil consumers in Canada
    (2024-07-22) Faghihi, Negin; Hobbs, Jill; Slade, Peter; Lubieniechi , Simona; Hesseln , Hayley; Yang, Yang
    Canada is a major producer and exporter of lentils, playing a significant role in the global pulse market. Understanding current and future trends in consumer preferences for lentils is crucial not only for the Canadian pulse sector, but also for lentil breeders and producers around the world. Canada is a highly diverse, multicultural country, making it an ideal setting to investigate lentil consumption patterns. This study uses survey data related to Canadian consumers with an ethnic tradition of lentil consumption as a proxy for understanding consumer behavior in other countries. By comparing the preferences for lentils among consumers who are culturally associated with lentil-consuming countries (traditional lentils consumers) and those who are not (non-traditional lentils consumers), the research aims to shed a light on the factors shaping the Canadian lentil market. An online survey of 1236 Canadian consumers was conducted to assess the differences in preferences among traditional versus non-traditional lentil consumers in Canada. Data are analyzed using Probit model. The results show that traditional lentil consumers, consumers for whom physical attributes of lentils are important, people who respect environmental issues, people who care about health, people who believe that lentils are easy to cook, and people who believe plant-based proteins like lentils are more affordable compared with meat, are more likely to consume lentils frequently. Also based on this research, consumers for whom animal rights are important, are less likely to consume lentils frequently. Consumers between 25-54 years old are more likely to be frequent lentil consumers relative to people 65 and above. Also, consumers with a postgraduate education level, are more likely to consume lentils frequently, relative to people with a bachelors’ degree. Also, avoiding consuming GMO-products and animal rights are more important for traditional consumers while physical attributes of lentils, convenience and affordability are more important for non-traditional lentils consumers.
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    Does pasture rejuvenation by sod-seeding with non-bloat legumes affect greenhouse gas emissions?
    (2024-07-22) Liu, Can; Farrell, Richard; Peak, Derek; Baulch, Helen; Knight, Diane; Lemke, Reynald; Bourgault, Maryse; Wallace, Brian
    Pasture rejuvenation through sod-seeding (i.e., the use a zero-till drill to place the seed directly into the soil) with non-bloat legumes, such as cicer milkvetch (Astragalus Cicer L.) or sainfoin (Onobrychis vicifolia Scop.), has emerged as a favored strategy for ranchers in the western Canadian prairies due to it being both time- and cost-effective. Meanwhile, this management also makes alterations to soil carbon and nitrogen cycling as well as to the diet of cattle grazing the pastures. Yet, our understanding on how these changes influence the greenhouse gas (GHG) budgets of the pastures remains limited. The goal of this research was to assess the impact of rejuvenating pastures by sod-seeding cicer milkvetch or sainfoin into a depleted meadow bromegrass-alfalfa mixed pasture on GHG emissions and their contribution to the total GHG footprint of the pasture system. To achieve this goal, field studies were conducted in east-central Saskatchewan, Canada to: (1) evaluate and compare GHG emissions between the rejuvenated pastures and the depleted pasture, and (2) quantify GHG emissions from dung and urine patches deposited by cattle grazing these pastures. Finally, the legume option resulting in the lowest GHG footprint was identified by integrating the GHG data with enteric methane (CH4) production by the cattle. The results indicate pasture rejuvenation through sod-seeding had only a minimal impact on soil-derived GHG emissions relative to the control (depleted) pasture, likely due to the limited soil disturbance associated with this method. At the paddock-scale, annual GHG emissions averaged 10.11 Mg CO2-C ha-1, 2.54 kg CH4-C ha-1 (uptake), and 0.18 kg N2O-N ha-1, with no significant differences among pasture types. However, changes in grazing diet resulting from the pasture rejuvenation were found to affect urine patch N2O emissions, with the highest cumulative N2O emissions associated with beef cattle grazing on the depleted pastures sod-seeded with cicer milkvetch. Surprisingly, this did not reflect differences in the available N content of the urines, suggesting a potential link to the presence of secondary metabolites such as hippuric acid. Notably, the dung and urine patches yielded distinctly different N2O emission factors, averaging 0.03% and 0.26%, respectively. Within the pastures, landscape position emerged as a dominant regulatory factor for CO2 and CH4 emissions—with the lower slope positions exhibiting the highest CO2 emissions and the lowest CH4 uptake, likely due to denser vegetative cover in these areas due to an accumulation of soil moisture. Such landscape-scale patterns remained unaffected by dung/urine deposition. Partial C footprints for the pastures (based on non-CO2 emissions from the soil, cattle excreta, and enteric CH4) were developed and it was determined that there were no significant differences between the rejuvenated and depleted pastures. Averaged across pastures, the C footprint was 970 kg CO2eq ha-1 yr-1, with enteric CH4 being the largest contributor to the footprint. Insights gained from this study will be valuable for ranchers and policymakers in developing sustainable pasture management strategies.
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    THE MICROBIOME AND THE REPRODUCTIVE ECOLOGY OF Dermacentor variabilis AND Dermacentor andersoni IN WESTERN CANADA
    (2024-07-22) Diyes, Chulantha Prasanga; Chilton, Neil B; Gray, Jack; Hegedus, Dwayne; Davis, Art; Erlandson, Martin; Voordouw, Maarten; Tsao, Jean
    The geographical ranges of the Rocky Mountain wood tick, Dermacentor andersoni, and the American dog tick, Dermacentor variabilis, are largely allopatric on the Canadian prairies. Range expansion by D. variabilis to the north and west has resulted in an area of sympatry in south-western Saskatchewan, where both tick species experience similar environmental conditions. In this thesis, I examined the reproductive output, egg development, off-host survival of larvae, larval behaviour, and transovarial transmission of bacteria by D. andersoni and D. variabilis. I also compared the microbiomes of engorged females, their eggs and larvae of the two species using next generation sequencing and quantitative PCR assays. The results showed a strong correlation between the engorgement weight and the number of eggs laid by females. Dermacentor andersoni exhibited higher fecundity than D. variabilis. Egg development time and larval survival were significantly influenced by temperature and relative humidity. Eggs took less time to hatch at higher temperatures, with D. andersoni eggs developing faster rate than those of D. variabilis. Unfed larvae of both species had reduced survival at a low relative humidity, but D. andersoni were able to tolerate drier conditions than D. variabilis. Furthermore, a behavioral diapause was observed in D. variabilis larvae but not in D. andersoni. This indicated an adaptive strategy by D. variabilis to synchronize the life cycle with the onset of winter. A field experiment was also conducted to determine the survival of unfed D. variabilis larvae in field enclosures during which time they experienced sub-zero temperatures. Over 95% of larvae survived. The results of a second field experiment showed that leaf litter covered by snow is crucial for the overwinter survival of unfed D. variabilis larvae. The core microbiomes of D. variabilis females, eggs, and larvae were predominantly composed of Francisella-like endosymbionts (FLEs) and Rickettsia montanensis, whereas the core microbiomes of D. andersoni consisted of FLEs, Arsenophonus, Rickettsia peacockii and/or Rickettsia sp. 2. The presence of FLEs, R. montanensis, R. peacockii, Rickettsia sp. 2, and Arsenophonus in eggs and larvae is indicative of transovarial transmission by female ticks. The relative abundance of R. montanensis in unfed D. variabilis larvae exposed to fluctuating environmental conditions dramatically increased during the winter months. These findings for D. variabilis from recently established populations at the northern part of the species range, and for prairie and montane populations of D. andersoni, provides insight into what may limit their distributional ranges.
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    Evaluating the innate immune functions of porcine gamma-delta T cells
    (2024-07-22) Bettin, Leonie; Gerdts, Volker; Napper, Scott; Loving, Crystal; Käser, Tobias; Lunney, Joan; Wilson, Heather
    Gamma-delta (γδ) T cells, a distinct subset of T cells, play a crucial role in immune responses and surveillance due to their unique characteristics. While γδ T cells are a rare cell population in human blood, they are enriched in many peripheral tissues. Unlike conventional T cells, γδ T cells have diverse mechanisms of antigen recognition. These mechanisms include the recognition of unconventional antigens, like stress molecules and non-peptide antigens, independent of the presentation via MHC molecules, enabling them to respond rapidly to invading pathogens or other stressors. Over the years many innate-like functions have been described for human and murine γδ T cells, for example, the direct recognition of pathogens through Pattern Recognition Receptors, the MHC-unrestricted activation and polyclonal proliferation. In terms of effector functions, γδ T cells mainly exhibit cytotoxicity against infected or other dysregulated cells and proinflammatory cytokine production (IL-17, IFNγ). In contrast to humans, pigs belong to the “γδ high species” characterized by a high frequency of circulating γδ T cells. Especially in young pigs about 50-60% of T cells are γδ T cells. Despite this abundance, the role and function of porcine γδ T cells within the immune system and developmental effects are largely unknown. Thus, this thesis tested the hypothesis that porcine γδ T cells can function as innate immune cells and can change phenotypically and functionally with age. First, we successfully characterized the phenotype of γδ T cells in circulation. We determined that the main phenotype of γδ T cells changes from CD2−CD8a−/dimCD27+ in young pigs to CD2+CD8ahighCD27− in 3-year-old pigs. Moreover, we identified TLR transcript in porcine γδ T cells with the highest level observed for TLR7 and TLR8. TLR7 and 8 were not only expressed on the transcript level but were also functionally relevant as we demonstrated a direct effect of TLR7/8 ligand (R848) on porcine γδ T cells. Cytokine production (IFNγ) by γδ T cells from young and adult pigs was potently stimulated by R848 in combination with IL-2 and IL-12 with stronger responses from adult pigs. On top of the differences in γδ T cell phenotype and cytokine production with age, γδ T cells from different age groups seem to differ in the downstream signaling induced by TLR7/8 activation as demonstrated by kinome analysis and flow cytometry. Our data revealed significant involvement of the kinases IRAK1/4, p38 and JNK in the TLR7/8 induced co-stimulation in adult γδ T cells, potentially indicating an involvement of the MyD88-dependent pathway. Gamma-delta T cells from young pigs, mainly consisting of CD2- γδ T cells, seem to utilize alternative signaling pathways that did not involve IRAK1/4 or JNK. As TLR7 and TLR8 play pivotal roles in recognizing viral RNA and IFNγ is a cytokine with direct antiviral properties, we may have uncovered an antiviral innate function of  T cells: the direct recognition of RNA viruses leading to IFNγ production and subsequently activating downstream immune responses. Besides pro-inflammatory cytokine production, human γδ T cells are also known for their broad cytolytic activity towards infected/stressed cells. In this thesis, we discovered that only CD2+ γδ T cells express cytotoxic effector cell-associated markers and that γδ T cells can exhibit cytolytic functions in vitro. Unexpectedly, this cytotoxic activity was not exclusively directed at infected cells; rather, it appeared to be broader in scope, as uninfected cells were also targeted. It remains to be seen what target cell recognition mechanisms are employed by porcine γδ T cells, but it is plausible that the recognition of cellular stress plays a role. Overall, my thesis supports the understanding of γδ T cells as an immune cell subset engaged in innate immune responses and stress surveillance.
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    Don't Steal My Days, I'll Give Them To You
    (2024-07-19) Bliss, Daniel; Lynes, Jeanette; Benning , Sheri; Martin, Ann; Ruzesky, Jay
    Don't Steal My Days, I'll Give Them to You comprises narrative, lyric poems that explore the complex relationship between place and human experience. The collection expands across various themes, including loss, coming of age, family, health, and more, while set in a range of places, including those both traveled to for a short amount of time, and those inhabited by the speaker for years. The places in my poems help call forth human experiences, while showing how place and identity are intertwined. Don't Steal My Days, I'll Give Them to You emerges out of my experience as someone who grew up in the nomadic lifestyle of the military. I have never stopped moving, and as such am fascinated with how place and selfhood intertwine.
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    The Impact of Phosphorylation, Nutrient and Stress Signaling on Fkh1 Regulation
    (2024-07-19) Brakstad, Jordan; Arnason, Terra; Eames, Brian; Verge, Valerie; Bandy, Brian
    The abstract of this item is unavailable due to an embargo.
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    House of Modular Enhancement (HOME): A Design Tool for Product Modularization
    (1999) Sand, Jeffery Christopher; Gu, P.; Watson, L. G.
    The intent of modularization is to develop products with modules that are easy to develop, while improving the overall design, manufacturing and operational characteristics of the product. The greater the reduction of inter-modular interactions, the more successful the modular outcome. A product that has been modularized, can greatly assist the reconfiguration of the product, reducing the lead time of design and manufacturing while providing benefits like upgrading, maintenance, customization and recycling. In order to achieve the aforementioned benefits of modularization, a methodology is required to modularize products. This thesis provides a detailed description of a new modular design methodology called the House Of Modular Enhancement (HOME). HOME is a modular design tool that assists the designer with the modularization of a product. Information from all aspects of the design is incorporated into the procedure to help ensure a modular outcome that is best suited to the product under consideration. The HOME methodology has been implemented in a software system that manages all aspects of the procedure. Two case studies were carried out to illustrate the HOME process in its entirety.
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    Scour Protection Below Overhanging Culvert Outlets
    (1979-05) Johnson, Shane R.; Smith, C.D.
    Protection below overhanging culvert outlets is required to prevent scour and negate or minimize pipe undermining. Large culverts may need reinforced concrete protection, but for smaller culverts a more economical and satisfactory means of protection can be provided by using field stone. A three-dimensional model study of scour below overhanging culvert outlets was made. Testing in a plain sand bed was done first in order to outline the process by which scour occurs at an overhanging culvert outlet and the extent to which it occurs. Preliminary tests on the placement of rip-rap to reduce scour were then done to test various placement configurations. These tests were qualitative and no design procedure came about from their results. Testing in a plain rock bed was then done, and from this series of tests a design procedure for protection against scour at an overhanging culvert outlet was formulated.
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    GENDER ROLE CONFLICT AND LOCUS OF CONTROL IN DETERMINING PSYCHOLOGICAL HELP SEEKING
    (1997) Granley, Heath Dean; Yackulic, A.; Van Hesteren, F.; Pawlovich, W.; Scissons, E.
    In an attempt to understand why men avoid or delay seeking counselling, the literature revealed that many men experience gender role conflict, due to a fear of femininity, and that this fear may inhibit some men from seeking help because many of the aspects of seeking help are considered feminine. The research also suggests that most men have more negative attitudes toward seeking help than women, as do individuals who have an external locus of control. The purpose of this study was to examine the relationships between gender role conflict, locus of control, and attitudes toward seeking help in a nonclinical sample of 190 university men. The male subjects completed the Gender Role Conflict Scale, the Attitudes Toward Seeking Professional Psychological Help Scale, and the Adult Nowicki-Strickland Internal-External Locus of Control Scale. Correlation analyses conducted revealed that there were significant negative relationships between gender role conflict and attitudes toward seeking help as well as between locus of control and attitudes toward seeking help. A significant positive relationship between gender role conflict and locus of control was also found. A multiple regression analysis was conducted and revealed that gender role conflict and locus of control were moderate predictors of attitudes toward seeking help, accounting for 21.1 % of the variability in attitudes toward seeking help scores. Although the results were found to be significant, it is not inferred that gender role conflict is the predominant reason why men do not seek help and other factors need to be investigated to better understand this complex phenomenon.
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    HEIGHT ESTIMATION USING STEREO SIGNAL PROCESSING
    (1989-07-27) Randhawa, Tejinder Singh; Salt, J. E.; Wood, H. C.
    A sensor system, which estimates the mean height of the plane of the sensors above the ground surface, has been proposed and analysed in this thesis. The sensor system consists of two spatially separated optical sensors and a signal processor. The signal processor consists of four subsystems : a crosscorrelator, a filter, an averager and an amplifier. Although this sensor system has a wide range of applications, its applicability in estimating the height of agricultural machines above the ground surface is analysed in par-ticular in this thesis. A mathematical model of the system has been developed. The output signals of the two sensors are modelled as a common signal, time-shifted in the case of one of the sensors, and corrupted by additive noise signals. The shift in the output signals is a function of the height variations of the ground surface. For the purposes of the analysis, the common signal is assumed to be the sample function of a correlation ergodic process and the noise signals are from mean ergodic processes with zero mean. The time varying shift is assumed to be the outcome of a distribution ergodic process. The common signal, the noise 'signals and the shift signal are assumed to be mutually independent and thus uncorrelated. With these two signals as the inputs, the output of the signal processor is the mean height. The output of the crosscorrelator has been proved theoretically to be the convolution of the autocorrelation function of the common signal with the probability density function of the shift. The filter recovers the density function from the crosscorrelator output. The expression of the filter response has also been derived in this thesis. The averager calculates the mean delay, which mul-tiplies with the gain of the amplifier to give the mean height. The model is analysed using computer simulations. Different types of shift signals are used in simulations to verify the working theory of the sig-nal processor. To test the feasibility of the system in estimating the mean height in real time, some preliminary data have been collected using a prototype system. The data have been processed and the results are presented. Some general conclusions are drawn about the efficiency as well as the limitations of this system in estimating the mean height under prac-tical situations.
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    DEVELOPMENT OF A COMPOSITE CUSTOMER DAMAGE FUNCTION
    (1985-04) Ramesh, Subramaniam Kumar; Wacker, G.; Billington, R.
    Attempts to relate the worth of electric service reliability to the cost of providing that reliability is becoming n important aspect of power system planning and operation. Evaluation of the economic or socioeconomic worth of power system reliability is a complex task and is often approached by assessing the cost of unreliability, ie: the losses incurred as a result of electric power interruptions) This thesis presents a possible methodology to use customer cost—of—interruption data to develop procedures to obtain a composite customer damage function. Conceptually, this function is a combination of the interruption losses of all electrical customers weighted in proportion to their energy utilization for a particular service area. This thesis also describes the customer related and interruption related variables which affect the customer damage function, making use of actual data to illustrate the effects.