Scholarworks

ScholarWorks is an open access repository for the capture of the intellectual work of Montana State University (MSU) in support of its teaching, research and service missions. MSU ScholarWorks is a central point of discovery for accessing, collecting, sharing, preserving, and distributing knowledge to the Montana State University community and the world.

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The invasion of annual grasses Bromus tectorum and Ventenata dubia in the American west: competition and management
(Montana State University - Bozeman, College of Agriculture, 2025) Sencenbaugh, Lilly Lin; Chairperson, Graduate Committee: Lisa J. Rew; This is a manuscript style paper that includes co-authored chapters.
Semi-arid rangelands in the American West have been invaded by non-native annual grasses, including Bromus tectorum and Ventenata dubia. These species threaten biodiversity, forage quality, and habitat. They have different spatial distributions but do sometimes co-occur, and concerns have been raised that V. dubia is replacing B. tectorum. Current and potentially greater range overlap should be considered in management contexts, as interactions between these species may enhance negative impacts or cause counter-effective responses to management. Management of invasive grasses is often achieved through herbicides, however, novel strategies like biofumigation should be studied. Biofumigation, the use of bio-active Brassica by-products, may target germinating seeds making it a potential tool for managing invasive annual grasses. The goal of this research was to elucidate the competitive dynamics between B. tectorum and V. dubia and determine whether biofumigation may be a management strategy. To quantify competitive interactions, an addition series study of B. tectorum and V. dubia was conducted. Both were negatively impacted by intraspecific and interspecific competition. To determine if plant-soil feedback (PSF) was affecting competition, I repeated the addition series in three soils (Neutral, B. tectorum, and V. dubia), over two experimental phases. Both were impacted by intraspecific competition in Phase 1, but by Phase 2 intraspecific competition was weakened in conspecific soil, suggesting a positive PSF. Next, I quantified the responses of B. tectorum, V. dubia, and two perennial grasses to biofumigation over two experiments. First, through a dose- response experiment with two biofumigants (seed meal and mulch). Seed meal reduced viability for our annual species and one perennial. Mulch was not consistent in reducing viability. The second study was performed in soil using multiple techniques (seed meal, seed meal leachate, straw, and straw leachate), and combined with solarization. Emergence was inhibited using seed meal treatments, but straw treatments and solarization were not effective. These studies have helped improve our knowledge of how these species interact and respond to biofumigation and ways we can use targeted management of these invasive grasses. Ultimately, the invasion of non- native annual grasses is a complex issue involving competitive dynamics and requiring multifaceted integrated weed management strategies.
Solute bioconcentration mechanisms in biological material
(Montana State University - Bozeman, College of Letters & Science, 2025) Trousdale, Rhys Colbran; Chairperson, Graduate Committee: Robert Walker; This is a manuscript style paper that includes co-authored chapters.
Bioconcentration is a term used to quantify the concentration of a solute within an organism with respect to the source of exposure. Recently, bioconcentration has been a major field of study for analytical and environmental chemists since the rise of synthetic chemicals appearing within the environment. The work described here uses fluorescence spectroscopy, light scattering, and thermoanalytical techniques to describe the impact of bioconcentration mechanisms on the structure and function of biological material, including model biological membranes and transport proteins. The studies performed in this body of work investigate solute-membrane and solute-protein interactions by analyzing the behavior of both the solute, and the biological material of interest in order to uncover the wholistic effect of the solute on a biological system. Each body of work either altered the solute studied for bioconcentration or the biological material itself, to get a deeper understanding of bioconcentration mechanisms. The first body of work describes a study looking into the partitioning behavior of the amino acid L- Phenylalanine into model biological membranes. Experiments showed that L-Phenylalanine integrates into the membrane and experiences a conformationally restricted environment. The second body of work inspects an environmental contaminant known as Perfluorooctanoic acid (PFOA), and the effects it has on lipid bilayer vesicles structure, as well as secondary solute partitioning behavior at concentrations close to the EPA regulatory limits. Experiments revealed that 100 nM PFOA increases membrane fluidity and increases secondary solute partitioning into the acyl chains of the lipid bilayer. The third body of work explores Perfluorooctanoic acid's effects on the protein Human Hemoglobin, and discovered that PFOA induces a change in the fluorescence mechanism of the native Tryptophan residues, and binds at concentrations as low as 10 nM.
Physical activity, muscle quality, and reactive balance control in community-dwelling older adults
(Montana State University - Bozeman, College of Education, Health & Human Development, 2025) Whitten, Justin Mark Moeller; Chairperson, Graduate Committee: John G. Seifert; This is a manuscript style paper that includes co-authored chapters.
Falls are a leading cause of injury, disability, and mortality among older adults, yet existing fall prevention strategies have not effectively reduced fall rates. Despite widespread recommendations promoting general physical activity and conventional balance training, falls and fall-related deaths continue to increase. One potential reason for this limited success is that conventional interventions primarily focus on proactive balance control and functional capacity, while most falls arise from unexpected perturbations that necessitate rapid reactive balance responses. Perturbation-based balance training (PBT) has emerged as a promising strategy to improve reactive balance control and lower fall risk, but its feasibility, effectiveness, and broader implementation remain insufficiently explored. Through three studies, this dissertation investigated key factors contributing to fall risk and balance recovery in older adults. Study 1 examined whether habitual physical activity and conventional functional assessments can predict future falls in community-dwelling older adults. Results showed no significant association, suggesting that traditional measures may not adequately capture the neuromuscular mechanisms crucial for fall prevention. Study 2 explored the link between lower limb muscle quality and balance recovery, finding that biceps femoris muscle quality was related to improved reactive balance responses. This preliminary evidence underscores the potential role of muscle composition in assessing fall risk. Study 3 evaluated the acceptability and feasibility of a community-based PBT program, revealing that while older adults and healthcare providers regarded PBT as beneficial, cost and accessibility posed barriers to widespread adoption. Collectively, these findings reinforce the need for a paradigm shift in fall prevention, emphasizing targeted assessments and interventions that specifically enhance reactive balance control. Future research should focus on refining assessment tools, optimizing PBT protocols, and developing cost-effective methods for integrating reactive balance training into clinical and community settings. Addressing these gaps is essential for advancing fall prevention strategies and improving outcomes for older adults at risk of falls.
Improving chronic migraine assessment in primary care: a quality improvement project
(Montana State University - Bozeman, College of Nursing, 2025) Tamcke, Autumn Boutin; Chairperson, Graduate Committee: Benjamin J. Miller; This is a manuscript style paper that includes co-authored chapters.
Background: Migraine is a leading cause of disability, yet standardized assessment tools are underutilized in primary care settings. The MIDAS (Migraine Disability Assessment Scale) offers a structured approach to evaluating migraine-related disability, but its integration into clinical practice remains inconsistent. Local Problem: A small primary care clinic and urgent care in Montana lacked a standardized approach to assessing migraine impact, limiting effective treatment planning. Prior to the intervention, 0% of migraine patients had a documented disability assessment, and provider confidence in using disability-based tools was low. Methods: Participants included primary care providers (PCPs) and adult patients diagnosed with migraines. Over a six-week quality improvement (QI) initiative, provider education and the use of the MIDAS tool were implemented. Outcomes were measured biweekly, including provider confidence in assessing migraine-related disability, the percentage of eligible patients receiving MIDAS screening, and treatment modifications based on MIDAS scores. Intervention: Providers viewed and completed an educational session covering migraine pathophysiology, treatment options, and the role of the MIDAS tool. The screening tool was integrated into practice with patients with a chief complaint of headache or migraine. Structured guidance on interpreting results and optimizing treatment plans for chronic migraine patients was provided. Results: Among 35 eligible patients, 43% (n=15) received MIDAS screening, a significant improvement from baseline (0%). Provider-reported confidence in using the tool increased by 100%. Of those with moderate to severe disability (MIDAS score > or = 11), 70% (n=7) had treatment modifications, including 50% (n=5) receiving preventive therapy adjustments. Patient-reported quality of life scores improved by an average of 33% over six weeks. Conclusion: Standardizing migraine disability assessment with the MIDAS tool improved provider confidence, guided treatment adjustments, and enhanced patient outcomes. Long-term follow-up is needed to evaluate sustained integration and impact.
An investigation of study design and prior selection in Bayesian occupancy models
(Montana State University - Bozeman, College of Letters & Science, 2025) Winder, Meaghan Elizabeth; Chairperson, Graduate Committee: Andrew Hoegh; This is a manuscript style paper that includes co-authored chapters.
Ecological data are inherently complex and often require making inferences about quantities that are not directly observed. To estimate these unobserved quantities, statisticians typically employ hierarchical modeling techniques. Detection/non-detection data, often referred to as occupancy data, are collected by ecologists and biologists to address a wide range of ecological questions; these inquiries may include, but are not limited to, questions about species distributions, changes in species distributions over time, or species detectability. Occupancy data are particularly well suited for analysis using hierarchical occupancy models. In this work, we present novel methods and recommendations for a variety of Bayesian occupancy models, focusing on improving accessibility for practicing scientists; in our work, we emphasize both study design and prior selection as critical components for enhancing analyses to better address ecological questions. Specifically, we identify methodological modifications and sampling recommendations to guide early detection monitoring of invasive dreissenid mussels in the western United States. We provide sampling and modeling recommendations for long-term ecological monitoring projects in the presence of incomplete data. We offer a flexible method for implementing Bayesian regularizing priors in the occupancy modeling framework, and offer an accessible tool for implementing the technique in R.