Theses and Dissertations at Montana State University (MSU)
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Item Using dietary dynamics to assess the efficacy of biocontrol and to predict the effects of warming water temperatures on salmonids(Montana State University - Bozeman, College of Letters & Science, 2024) Furey, Kaitlyn Marie; Chairperson, Graduate Committee: Christopher S. Guy; This is a manuscript style paper that includes co-authored chapters.Salmonids are coldwater fishes with substantial ecological and economic importance, particularly in the northern Rocky Mountains in Montana, USA, where fisheries are valued over US$750M annually. Georgetown Lake (Montana, USA) is renowned for its salmonid fishery. Although many anglers target kokanee (Oncorhynchus nerka) in Georgetown Lake, the body length of kokanee has typically been considered unsatisfactory. To reduce the density of kokanee and increase the average size, Montana Fish, Wildlife & Parks (MFWP) began stocking piscivorous Gerrard strain of rainbow trout (Oncorhynchus mykiss; hereafter Gerrard) in 2015 to consume kokanee. To assess the efficacy of biocontrol through the introduction of a piscivore to improve the size structure of kokanee, I used diet composition to determine the amount of predation on kokanee and to understand the feeding ecology of all potential predators. There was extremely low prevalence of piscivory and no evidence of Gerrards consuming kokanee. Gerrards exhibited a generalist feeding strategy and there was dietary and niche overlap and no difference in trophic position among Gerrards and trout. These findings highlight the unpredictability of predator-prey dynamics and the importance of evaluating management interventions, such as biocontrols. Additionally, this popular fishery could be in jeopardy because air temperatures in the region have warmed at twice the global average, leading to warmer water temperatures that could affect the thermal suitability for salmonids. Increased water temperatures can have sub-lethal effects, influencing growth, metabolism, and feeding rates of fish. Bioenergetics models were used to simulate the effects of warming water temperature on food consumption and growth for rainbow trout and kokanee within Georgetown Lake. My findings indicate that kokanee are more sensitive to warming than rainbow trout. While both species experience growth challenges as water temperatures exceed their optimal ranges, kokanee are particularly vulnerable, requiring higher food consumption to meet basic metabolic needs under elevated water temperatures. Thus, kokanee are likely to experience greater declines in growth compared to rainbow trout. Climate change will pose challenges for freshwater fisheries management, thus understanding how projected warming water temperatures may affect popular recreational fisheries can provide managers with information to establish reasonable expectations for fish growth.Item Sparse descriptors for whole graph embedding and dictionary based feature ranking(Montana State University - Bozeman, College of Engineering, 2024) Liyanage, Liyanpathige Kaveen Gayasara; Chairperson, Graduate Committee: Brad WhitakerGraph representation has gained wide popularity as a data representation method in many applications. Unfortunately, most data processing techniques cannot be applied directly to a graph structure. Therefore, graph embedding methods are frequently used to convert graphs to vectors. While such methods are essential in standard data processing pipelines, they often result in complicated, nonlinear, and high-dimensional mappings. The goal of this dissertation is to utilize sparse dictionary learning techniques in the context of graph embedding. In contrast to traditional graph embedding methods, sparse representations are linear by design. This linearity also leads to intuition, since the building blocks of a sparse dictionary are directly related to the input space. Despite the potential advantages of sparse processing and the ubiquitousness of sparsity in other signal processing domains, its applications in graph embedding are not well studied. This dissertation consists of three main tasks. First, a novel sparse graph descriptor algorithm is presented, inspired by the Graph2Vec graph embedding algorithm. Second, sparse representation-based feature ranking metrics are deployed to identify important sub- tree structures of the graphs that can be used to define a dictionary. The developed embedding algorithm and feature-ranking metrics are compared to existing graph embedding methods and feature-ranking algorithms on several typical benchmark graph datasets. Finally, these sparse representation-based techniques are applied to control flow graphs of binary files to detect malware, showing the utility of the developed algorithms.Item Redefining the gap: considering opportunity factors on academic success outcomes for Montana students(Montana State University - Bozeman, College of Education, Health & Human Development, 2024) Frieling, Nicole Pamela; Chairperson, Graduate Committee: Carrie B. MyersThis study examines educational inequity among Montana high school students by investigating the influence of social location (gender, race, and socioeconomic class) and opportunity factors (student mobility and poverty) on academic achievement and completion. Using a robust multilevel modeling approach, this research analyzes longitudinal student and school data to address four primary questions: differences in academic success based on students' social locations, and the impact of individual and school-level factors on achievement and graduation likelihood. Key findings reveal that high-poverty male and American Indian/Alaskan Native (AIAN) students face compounded barriers to academic success, with significant disparities in both ACT performance and graduation rates. Analysis of the within-group sample of AIAN students highlights the role of mobility and poverty as critical opportunity factors, underscoring the distinct challenges faced by Native students, particularly those attending on- reservation schools. The study's results contribute to the understanding of how intersecting social locations impact educational outcomes and challenge the traditional "achievement gap" framework. Recommendations include expanding Montana's educational reporting to address nuanced disparities across social locations and implementing support systems tailored to high- poverty and mobile students. This research emphasizes the need for data-driven policy reform to promote equity and address systemic barriers within Montana's educational landscape. While this study's findings show a statistically negative relationship between mobility and academic outcomes, they should be interpreted with care, as mobility encompasses complex experiences and cannot be fully understood through quantitative data alone. Recognizing mobility as an opportunity factor captures this nuance, as mobility may present significant challenges for some students while providing meaningful opportunities for others, such as a move to a more stable home environment. This study highlights the need for both quantitative and qualitative approaches to truly unearth the multifaceted role that mobility plays in Montana, reminding us that interpreting mobility solely as a barrier risks overlooking its potential as a positive force in students' lives.Item Estimating tool wear using multi-sensor data fusion and machine learning techniques(Montana State University - Bozeman, College of Engineering, 2024) Jones, Tanner Owen; Chairperson, Graduate Committee: Yang CaoModern manufacturing industries are being transformed by the integration of sensor technology, data science, and machine learning, leading to smarter, more efficient operations. Advancements in equipment health monitoring are crucial for improving productivity, extending equipment lifespan, and ensuring consistent product quality. In computer numerical control (CNC) machining, worn tools contribute to increased forces and vibrations, negatively impacting both machine performance and part quality. Traditional tool condition monitoring methods, which rely on manual offline inspections, result in machine downtime and decreased productivity. Modern tool condition monitoring methods involve monitoring tools based on single-sensor analysis. While a single sensor can detect tool wear within a machine, it fails to capture the full range of system behavior, potentially overlooking critical anomalies indictive of tool wear. To address these challenges, automated monitoring systems utilizing multisensory data and machine learning techniques have been developed, enabling real-time monitoring and prediction of tool wear. This research introduces a novel three-level data fusion framework for predicting tool flank wear in CNC machining. Force, vibration, and sound data was collected using various sensors during a CNC milling operation. The raw sensor data was processed and transformed into distinct statistical features to train machine learning models. A stacking ensemble method combining a random forest, artificial neural network, and extreme gradient boosting algorithm was employed to enhance predictive accuracy, achieving an R 2 value of 0.982, and root mean squared error of 37.146 micrometers. The proposed three-level fusion framework proved to be highly effective in predicting tool flank wear and shows great potential for monitoring the health of engineering equipment across a variety of industries.Item Soil and stream corridor biogeochemistry of nitrate and sulfate and the influence of hydrologic connectivity in an agricultural system, Judith River Watershed, Montana(Montana State University - Bozeman, College of Agriculture, 2024) Mayernik, Caitlin Marie Mitchell; Chairperson, Graduate Committee: Stephanie A. Ewing; This is a manuscript style paper that includes co-authored chapters.Human activities across landscapes alter physical and chemical properties of soil, thereby influencing the movement and chemical composition of soil water. Soil hydrologic and biogeochemical processes thus mediate how land management influences the quality of water that passes through soil in route to groundwater aquifers and streams. Riparian areas are particularly important in mitigating the consequences of land use for the quality of water exported from watersheds. Soils, sediments, and shallow aquifers within riparian areas of stream corridors provide low oxygen environments favoring microbial transformation of solutes for energy and carbon. Despite the limited areal extent compared to the rest of the landscape, this unique biogeochemical character is disproportionately important in determining inorganic solute export, particularly in agricultural systems. For this dissertation, I investigated sources and fate of soil water in an area managed primarily for production of cattle and non-irrigated wheat within the semi-arid Northern Great Plains of North America. I explored patterns in solute concentrations and isotopic compositions across stream corridors draining cultivated soils to infer dominant hydrologic transport and biogeochemical pathways influencing solute loading to ground and surface waters. I investigated the influence of agricultural practices and soil weathering on biogeochemical processes influencing solutes, to answer the overarching research question: How do upland soils and stream corridors influence water and solute loading from upland aquifers to stream channels in a semi-arid landscape managed for agricultural production? Results show that soils are important mixing reservoirs for seasonally variable sources of precipitation, and that water movement through soil transports nitrate and sulfate from cultivated soils. Stream corridors receiving these inorganic solutes from upland groundwaters facilitate biogeochemical pathways of production, transformation, and irreversible loss. Changes in the isotopic composition of these solutes relative to changes in their mass abundance inform gross production and loss in stream corridors at the catchment scale, revealing both internal production of sulfate and/or nitrate and more substantial nitrate loss than indicated by net changes between uplands and streams. Geomorphic constraints on hydrologic connectivity and the arrangement of riparian soils and sediments determine how stream corridors mitigate the consequences of land use on downstream water quality.Item [FeFe]-hydrogenase maturation: bridging dithiomethylamine ligand assembly during the biosynthesis of the H-cluster(Montana State University - Bozeman, College of Letters & Science, 2024) Balci, Batuhan; Chairperson, Graduate Committee: Joan B. Broderick; This is a manuscript style paper that includes co-authored chapters.[FeFe]-hydrogenases (HydA) demonstrated the highest catalytic competency to synthesize hydrogen gas by reducing protons under physiological conditions and has become a model catalyst in biohydrogen production. In vivo biosynthesis of the active site H-cluster of HydA requires a complex biocatalytic process that involves two radical S- adenosyl-L-methionine enzymes: HydG and HydE, and a [4Fe-4S] cluster binding GTPase: HydF. The maturation of the H-cluster starts with HydG, which cleaves tyrosine to synthesize CO and CN- ligands and provides [Fe II(CO) 2(CN)(kappa 3-cys)]- (synthon) as the product. Synthon is directly delivered to the second radical SAM enzyme HydE that is hypothesized to adenosylate and reduce two equivalents of synthon and subsequently dimerize and form [Fe I 2(mu-SH) 2(CO) 4(CN) 2] 2- ([2Fe] E). The final step in the assembly of the [2Fe] subcluster is DTMA ligand synthesis. In addition to HydG, HydE, and HydF chemistry, the in vitro maturation of HydA was also dependent on E. coli cell extract as a separate component presumed to provide essential components for the assembly of DTMA. We discovered the activating components as H-protein and T-protein of the glycine cleavage system (GCS), serine hydroxymethyltrans-ferase (SHMT), and small molecule substrates: serine and ammonium. Isotope labeling studies and ENDOR spectroscopy analysis revealed that the carbon and nitrogen atoms of DTMA ligand originate from serine and NH 4 +. We hypothesized that the DTMA ligand is assembled by aminomethyl-lipoyl-H-protein (H met) on the HydF-[2Fe] E complex. Consecutively, we demonstrated that HydA can be matured from a chemically synthesized [2Fe] E precursor, bypassing HydG and HydE, via a lysate-free semisynthetic maturation system with GCS components, SHMT, and corresponding substrates. Results emphasized the role of H met as the precursor for DTMA ligand. Refinement to the semisynthetic maturation, which now includes the [Fe-S] cluster carrier protein NfuA and high-CO-affinity variant Mb-H64L, resulted in significantly enhanced hydrogenase activities reaching 940 micromol H 2 min -1 mg - 1 HydA, a level of activity matches with catalytic rates of HydA matured in vivo. Under the refined semisynthetic maturation conditions, we determined that the [4Fe-4S] cluster of HydF is required to mature HydA. Results from site-directed mutagenesis studies on the HydF scaffold suggest that the [4Fe-4S] cluster plays a structural role in the maturation of HydA.Item Restoration and pollinator conservation: strategies for controlling invasive annual grasses on degraded tribal grasslands(Montana State University - Bozeman, College of Agriculture, 2024) McRyhew, Ian Issaia; Chairperson, Graduate Committee: Jane M. MangoldInvasive annual grasses (IAG) threaten Intermountain foothill grasslands in northwestern Montana, and these grasslands are integral to the cultural and ecological well-being of the Selis, Ksanka, and Ql'ispe Tribes. This project aimed to increase native vegetation cover and test the tolerance of native grasses and forbs to herbicides commonly used to control IAG. Three components were evaluated: a field study at two sites on Tribal grasslands, a greenhouse study of species tolerance, and a baseline bee survey at the two field sites. In the field study, six herbicides and nine species were tested, with herbicide treatments applied fall 2021 through summer 2022, depending on label recommended timings, and seeding occurring spring 2021. Canopy cover of all species was measured in 2022 and 2023. Rimsulfuron, sulfosulfuron, and indaziflam effectively reduced IAG (up to 96% control), while propoxycarbazone, imazapic, and glyphosate were less effective. Drill seeding largely failed. Geranium maculatum, Cleomella serrulata, and Gaillardia aristata were present in low numbers in 2022 but absent in 2023. The greenhouse study evaluated tolerance of 12 plant species to four herbicides, focusing on seedling emergence, biomass, and injury symptoms. Herbicides reduced emergence and reduced biomass for the majority of species compared to the non-sprayed check. All forbs showed high injury ranks except Lupinus argenteus, which ranked moderate across treatments. All grasses had high injury ranks across herbicides except Thinopyrum intermedium, which had the least injury of all species under sulfosulfuron. Although T. intermedium and G. aristata showed some emergence in indaziflam-treated soil, indaziflam prevented the emergence of all other species. A baseline bee survey conducted over three summer months in 2023 at the two field sites identified 42 bee species from 14 genera and five families. Species richness analysis predicted 48 species at one site and 74 species at the other site, indicating a relatively even distribution of species. To effectively manage IAG, rimsulfuron, sulfosulfuron, and indaziflam can be prioritized, but should be integrated with planting of specific native species to improve establishment and minimize non-target impacts. Restoration efforts should incorporate pollinator-friendly species and engage stakeholders to align management with cultural and ecological goals.Item Influence of cottonseed oil on fat oxidation in steady state exercise(Montana State University - Bozeman, College of Education, Health & Human Development, 2024) Kropatsch, Katy Rose; Chairperson, Graduate Committee: Mary P. Miles; This is a manuscript style paper that includes co-authored chapters.Impaired fat oxidation is a common issue in individuals with chronic disease such as obesity and cardiovascular disease. Nutrition interventions aimed at increasing fat oxidation capacity could potentially have clinical relevance in delaying the progression and/or preventing chronic disease. Dihydrosterculic acid (DHSA), a bioactive component in cottonseed oil (CSO), has previously been seen to increase fat oxidation in mice. However, it is unknown the effect of CSO on fat oxidation in humans. The purpose was to determine the impact of a diet rich in either cottonseed oil (CSO) or olive oil (OO), consumed at dosages of 60g or 30g per day for a duration of 28 days, on fat oxidation during a 30-minute steady-state exercise bout in a fasted state. Methods: Healthy adults (n=47, BMI<27 kg/m 2), aged 18 to 55, engaged in a 30-minute exercise test performed at 75% of relative VO2 max, pre- and post-dietary intervention. Over 28 days, participants were randomized to receive daily doses of 30g/day or 60g/day of either CSO or olive oil (OO). Using indirect calorimetry at 10-minute intervals during the exercise tests, fat oxidation in kilocalories per minute was calculated and summarized as area under the curve (AUC) at each time point. The shift in fat burning between pre- and post-intervention tests, were then computed. ANOVA was used to find differences between groups. Results: There were no significant changes in fat kcal/22 mins between all groups (p=0.43). Combining both CSO dosage groups revealed a trend increase in fat kcal/22 mins compared to OO (CSO: 5.89 + or - 4.89 kcals/22 mins, OO: -7.71 + or - 7.32 kcals/22 mins p=0.13). No differences were found between 30g and 60g dosages (p=0.51). Sexes showed a significant difference in change of fat oxidation, with females (8.69 + or - 4.28 kcals/22 mins) exhibiting an increase and males (-9.71 + or - 7.25 kcals/22 mins) a decrease (p=0.04). Change in fat percentage showed no significant differences between CSO and OO groups (p=0.98). Conclusion: These findings suggest that CSO may boost fat oxidation in humans, offering potential benefits for metabolic health.Item Effects of depleted competitors and prey on hunting, movement, and space-use of African wild dogs(Montana State University - Bozeman, College of Letters & Science, 2024) Goodheart, Benjamin Michael; Chairperson, Graduate Committee: Scott Creel; This is a manuscript style paper that includes co-authored chapters.Prey depletion is an increasing threat to many of the world's endangered carnivores, by impacting some of the few remaining protected areas critical for species' population persistence. Prey depletion intuitively reduces the density of apex carnivores because their populations are tightly correlated to prey density. Effects of prey depletion on subordinate competitors like African wild dogs are less intuitive, because their populations are strongly limited by their dominant counterparts. Recent research has demonstrated that the effects of prey depletion can impact subordinate carnivores in a similar manner to dominant guild members, with subordinate carnivore populations declining in parallel and not showing benefits of competitive release, despite the low densities of dominant competitors in prey depleted systems. Mechanisms that prevent competitive release and cause population reductions for subordinate carnivores have never been tested, yet are vitally important for conservation and understanding carnivore guild dynamics under an increasingly common threat to carnivore populations. We used long-term spatial, movement, and observational data from African wild dogs to test hypotheses regarding top-down and bottom-up effects of prey depletion, and made inferences in the context of long-term demographic analyses from both ecosystems, to identify the mechanistic causes of reduced wild dog population density and fitness as a result of prey depletion. In prey depleted ecosystems, our results indicate that wild dog movements continue to be affected by long and short-term risk of encountering lions despite their low densities and wild dogs continue to avoid lions, and areas with the highest densities of preferred prey. Prey depletion negatively affects every stage of hunting for wild dogs, and the combination of low prey density and loss of larger bodied ungulates, results in larger annual home-ranges and smaller pack size. These results indicate that prey depletion has negative bottom-up effects on wild dog populations while top-down limitations from dominant competitors remain strong, explaining the lack of competitive release and parallel reduction in density. This work provides new insights for large carnivore guild dynamics in prey depleted ecosystems and is the first to show compounding mechanisms that prevent competitive release for a subordinate competitor when dominant competitors are reduced.Item Mirror, mirror on the screen: LGBTQ+ college student experience with body image during COVID-19(Montana State University - Bozeman, College of Education, Health & Human Development, 2024) King, Amber Suzanne; Chairperson, Graduate Committee: Bryce HughesThis narrative study shares the lived experiences of LGBTQ+ college students with body image during the COVID-19 pandemic. Research has shown that viewing oneself on the computer screen and time spent viewing social media during COVID-19 has negatively impacted body image in many individuals. Most research on this topic has been completed with cisgender, heterosexual, white women. Expanding the literature to include research with marginalized and underrepresented populations is integral to fully understanding the impact COVID-19 has had on body image. This study interviewed LGBTQ+ college students at Montana State University who had been students at the institution during the spring 2020 and fall 2020 semesters at the onset of the COVID-19 pandemic. The research aimed to include the participant stories and offer space to the voices of the LGBTQ+ community on their experience with body image during COVID-19. The dissertation included interviews with six students who provided artifacts representing their experiences. Key findings were presented as four themes: 1. Mirror Image, 2. Time for Reflection, 3. Identity Development, and 4. Relationships, Supports, and Influences. These findings provided a window into the unique experiences of the LGBTQ+ participants and how they viewed body image during the pandemic. This dissertation shares the stories and the experiences to broaden the understanding of this topic within the LGBTQ+ community, expands the understanding of lived experiences during the COVID-19 pandemic, and offers insight into providing services and education in a way that fully considers diversity, equity, and inclusion.