K-State Electronic Theses, Dissertations, and Reports: 2004 -
Permanent URI for this collectionhttps://hdl.handle.net/2097/4
This is the collection for doctoral dissertations and masters theses and reports submitted electronically by K-State students. Electronic submission of doctoral dissertations was required beginning Fall semester 2006. Electronic submission for masters theses and reports was required beginning Fall 2007. The collection also contains some dissertations, theses, and reports from the years 2004 and 2005 that were submitted during a pilot test project. Some items before 2004 have been digitized and are available in K-State Electronic Theses, Dissertations, and Reports: pre-2004. Check the Library catalog for dissertations, theses, and reports not found in these collections.
All items included in this collection have been approved by the K-State Graduate School. More information can be found on the ETDR Information Page. Items within this collection are protected by U.S. Copyright. Copyright on each item is held by the individual author.
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Item Open Access Understanding material properties and performance enabled by molecular simulations and machine learning potentials(2025) Deng, HaoMachine learning potentials (MLPs) are being rapidly adopted to describe complex potential energy surfaces and to solve emerging materials science and engineering problems. Trained against quantum mechanical datasets, MLPs are versatile mathematical surrogates to describe various chemical and physical phenomena originating from atomistic interactions. MLPs are notably superior over classical interatomic force fields owing to their high training flexibility, efficiency, and accuracy. In this thesis, artificial neural network (ANN), sparse Gaussian process (SGP), and neural equivariant MLPs were developed and applied in the investigations of mechanical and thermodynamic behaviors of metals, main-group semiconductors, and perovskites. In Chapter 3, a high-dimensional NN potential (HDNNP) was developed for the condensed phase nickel. This HDNNP trained using the geometry and force data extracted directly from ab initio molecular dynamics can predict the melting point of face-centered cubic nickel within a few Kelvins of the true value. In Chapter 4, the thermodynamic stabilities of icosahedral boron allotropes, its phase diagram were predicted with a SGP MLP trained using an on-the-fly active learning scheme. In Chapter 5, a neural equivariant interatomic potential was employed to tackle challenges associated with the variations of elemental configurations in a high-performance air electrode perovskite (i.e., PrNi1-δCoδO3) for protonic ceramic electrochemical cell (PCEC) applications. MLP-based phonon calculations suggest that the Ni/Co occupancy affects lattice thermal and chemical expansions differently, impacting a tradeoff between PCEC performance and stability. In Chapter 6, the neural equivariant MLP was used to study BaZr1-δYδO3 (BZY), a proton-conducting electrolyte used in PCEC assembly, paving the way to provide solutions to improve scalability of future PCEC manufacturing.Item Open Access Geomechanical, Petrophysical, and Mineralogical properties of Limestone Samples from Kansas(2025) Osorio, NelsyThe use of limestone in aggregate production and infrastructure projects necessitates a comprehensive investigation of its geomechanical and mineralogical properties across various scales and conditions. This study investigates the geomechanical properties, specifically Young’s Modulus E, in core and aggregate limestone samples from Kansas through the investigation and assessment of mineralogical and petrophysical variables. The main objectives of this study were to: (1) assess E in relation to mineralogical, petrophysical, and scale-dependent variability in Kansas limestone and (2) develop predictive models for E. For these purposes, we collected 29 1-inch and 28 2-inch limestone samples and measured E using uniaxial experiments under dry and saturated conditions. We present regression-based models in combination with decision trees that allow for the estimation of E based on water content θ and quartz content for saturated limestone samples. By comprehensively examining the geomechanical, petrophysical, and mineralogical properties of Kansas limestone cores, this study facilitates their utilization and suitability as aggregates in concrete production and various construction applications for the Kansas Department of Transportation (KDOT).Item Open Access Evaluation of oral meloxicam in beef calves with neonatal calf diarrhea(2025) Neill, HannahObjective To examine behavioral and physiologic outcomes associated with the expression of pain in calves with naturally occurring neonatal calf diarrhea (NCD) and determine the impact of meloxicam administration on reducing these pain-related behaviors and outcomes. Methods Beef calves 3 to 30 days old with NCD and no comorbidities or prior NSAID or steroid administration were enrolled as clinical cases, and healthy beef calves were enrolled as controls. Clinical cases received either meloxicam (MEL group) or placebo (PLBO group) treatment; all controls received placebo. Over 7 time points, outcomes measured were substance P, prostaglandin E metabolite, mechanical nociceptive threshold, gait analysis, behavior analysis, physical examinations, and intake bloodwork. Results 20 calves with NCD and 8 healthy calves were enrolled. Prostaglandin E metabolite was significantly higher in calves with NCD than controls. Control calves were more reactive to pressure over the hip than calves with NCD, particularly those treated with meloxicam. Calves with NCD had shorter stride length and slower gait velocity compared to controls. Calves with NCD spent more time lying and more time lying with their head up compared to controls. Calves in the MEL group spent more time lying with their head down compared to PLBO calves. Conclusions Differences in mechanical nociceptive threshold, gait analysis, and lying behavior possibly indicated the presence of abdominal pain. Differences in head posture between MEL and PLBO calves suggest that calves treated with meloxicam may have been more comfortable. Clinical Relevance Calves with NCD may experience pain, and treating them with meloxicam may relieve that pain.Item Open Access Admixture compatibility and freeze-thaw resistance of concrete prepared using commercially produced limestone calcined clay cements(2025) Gara, AhmedAdmixture compatibility and fresh, hardened, and durability properties of mortars and concrete prepared using commercially produced limestone calcined clay cements (LC3s) were evaluated during this study. Incompatibility was evaluated for commercially available high range water reducers (HRWRs) and air entraining agents (AEAs) by studying the impact on flow diameters and initial setting time of mortars. Polyethylene-based HRWR was the least suited, whereas vinsol-based AEA was the most suited for use with LC3 cements. The high fineness of LC3 demanded a significantly higher dose of HRWR than control to achieve similar flow for mortars and slump and air content for concretes. Fresh properties (like slump, unit weight, and air content), mechanical properties (compressive and flexural strength) and durability properties (drying shrinkage and freeze-thaw resistance) were documented for LC3 concretes using standardized testing procedures. While all concrete mixtures produced satisfied the compressive and flexural strength requirements for paving concrete, concrete produced using one LC3 showed higher compressive and flexural strength than the control, whereas the concrete produced using another LC3 had lower compressive strength. Air-entrained LC3 concrete demonstrated adequate freeze-thaw resistance. Furthermore, LC3 concrete experienced lower drying shrinkage than the control. While LC3 concrete showed satisfactory mechanical and durability properties for paving application, the primary challenge was to achieve the desired fresh properties, like slump and air content.Item Open Access “I’m changing the story here:” Emotional schema formation and communication between caregivers and children(2025) Schmechel, LindeyEmotions are a universal human experience; however, much work remains to be done in terms of understanding the formation of emotions and beliefs related to them, and how one’s culture and/or identity may impact them. While research has been conducted regarding emotional regulation and emotional reactions, a deeper exploration into the processes regarding our core beliefs about emotions (i.e., emotional schemas) is necessary to bridge a gap in the existing literature. If caregivers are to make intentional choices about the messages they send children regarding emotions and emotional beliefs, something that has been found to have long- lasting impacts, it is important for researchers and those aiming to help them to better understand the process of creating emotional schema. In order to help caregivers create more effective and positive socialization experiences with their own children, it is imperative to first aid caregivers in distinguishing what they believe about emotions and why. To this end, this study used a qualitative narrative approach to (a) highlight commonly experienced socialization milestones around emotions across childhood, adolescence, and new parenthood and (b) provide recommendations for caregivers and professionals in helping fields (e.g., therapists, educators) based on these experiences. Guided by symbolic interactionism theory (Stryker, 2008) and utilizing a feminist framework (Biana, 2020), I conducted nine interviews with six caregivers of preschool-aged (3-5 years) children around the messages they received as children regarding emotions, how these shifted over time, and what meanings around emotions they would want their own children to have. Using thematic analysis to interpret these interviews (Braun & Clarke, 2022), the coding team identified five themes related to participants’ meaning-making around emotions: (a) Culture/Context, (b) Changes Over Time, (c) Intentionality, (d) Parenting as a Practice, and (e) Emotion-Specific. The findings of the interviews emphasize the important role that caregivers tend to play in their children's lives when it comes to the formation of emotional schema but also highlight how inherently embedded in our current culture these messages can be. Acknowledging the influence of both caregivers and societal norms on the formation of emotional schema is an important step in working to determine what fits for the child or not, to help parents more effectively communicate messages regarding emotions with their children, and to disrupt intergenerational patterns that have been repeated and caused harm for far too long.Item Open Access Supporting literacy development in secondary education: identifying and addressing student needs A curriculum program to assist secondary educators(2025) Schrick, AnnThis curriculum program is designed to help secondary teachers better support students who struggle with foundational literacy skills. It addresses a significant gap in secondary education, where many students face ongoing literacy challenges despite improvements in elementary reading instruction. The program provides teachers with practical, research-based tools and strategies for identifying and addressing reading difficulties through a Multi-Tiered Support Systems (MTSS) framework. Drawing from cognitive science and the Science of Reading, the program explains how the brain learns to read and offers evidence-based teaching methods, including structured literacy approaches. The content is delivered through an interactive online platform that includes assessment tools, lesson plans, and resources for differentiated instruction. The program emphasizes five key components of literacy: phonemic awareness, phonics, fluency, vocabulary, and comprehension, while incorporating both Scarborough's Reading Rope and Sedita's Writing Rope frameworks. This practical resource aims to empower secondary educators with the knowledge and tools they need to help struggling readers succeed, without requiring extensive additional training or resources.Item Open Access Modeling frameworks for resilience in socio-technical systems(2025) Okeukwu-Ogbonnaya, AdaezeIn the face of growing disaster frequency and severity, we aim to strengthen resilience across socio-technical systems. We develop several modeling frameworks to understand how communities prepare for and recover from disruptions that span interdependent infrastructures and communication channels. Although communities differ in structure and vulnerability, disasters uniformly strain both the physical networks and the social systems that support them. This dissertation examines resilience across two fronts: the operational resilience of communities within interdependent infrastructure systems and the communicative resilience of information flow within and between them. In the first part, we use a Markov Decision Process (MDP) framework to model failure-and-repair dynamics in binary hetero-functional graphs (HFGs) that couple power, water, and community infrastructures. We show that communities experiencing power outages respond more sensitively to prioritization strategies based on vulnerability or criticality, whereas those affected by water shortages are primarily influenced by service demand. To overcome the limits of binary HFGs, we introduce the Hetero-functional Agent-Based Infrastructure Toolkit (HABiT). HABiT enables fine-grained simulation of heterogeneous infrastructures and their interdependencies. We apply HABiT to a synthetic model of three communities with varying infrastructure access and social vulnerability. The simulation reproduces normal operations, disruptions, and recovery influenced by scarce resources, vehicle routing, and mobile repair crews. By incorporating stochasticity, we uncover variations in cascading failures and recovery patterns that deterministic models can miss. HABiT thus enables rapid evaluation of disruption scenarios and guides resource allocation and recovery planning under uncertainty. Recognizing that technical criteria alone may diverge from community priorities, we integrate community preferences into decision-making. We employ Large Language Models (LLMs) as proxy survey tools, generating simulated personas with diverse disaster experiences to obtain infrastructure-repair preferences. We aggregate these responses through a learning-to-rank algorithm, producing a total repair order that balances technical feasibility with social priorities. In the second part, we shift from infrastructure to information, examining how communication systems support or hinder resilience. Using survey data from three Midwest counties, we develop stochastic diffusion models that trace how information spreads through communities during both normal and disaster conditions. We integrate neighbors, online social networks, local news, cable news, and local government, mapping trust-based and interaction-based ties in each community. We find that trust in local government, frequent interaction with cable news, and social media strongly shape diffusion, with diffusion speed being independent of community size. We then extend this analysis to examine manipulation of information in online social networks. Using Twitter data from the 2016 United States elections, we analyze interactions between Russian troll tweets and public replies. We cluster historical user-interaction sequences and apply statistical tests to reveal diverse, unpredictable engagement behaviors. We find that trolls lacked a consistent strategy for provoking responses, although content with political figures generally attracted more attention.Item Open Access From TikTok to Truth Social: A data analysis of Gen Z’s platform preferences following the 2024 election(2025) Wagner, DawsonAs social media continues to shape political discourse, Generation Z has emerged as a distinct and influential demographic in U.S. elections. This study explores Gen Z’s social media platform usage during the 2024 presidential election and investigates how their political affiliation, gender, and opinions of platform owners relate to their usage habits and concern about misinformation. Using a quantitative approach, original survey data was collected from 188 Gen Z respondents at Kansas State University. Descriptive statistics and paired samples t-tests were conducted to compare usage frequency across platforms such as TikTok, Instagram, Snapchat, and Facebook. Independent samples t-tests and bivariate correlations were used to assess differences in usage patterns by vote choice, political ideology, and gender. Results show that TikTok, Instagram, Snapchat, and YouTube were the most frequently used platforms, while Facebook, X (formerly Twitter), and emerging platforms like Truth Social and Threads had significantly lower engagement. Liberal-leaning participants reported lower favorability toward platform owners like Elon Musk and Donald Trump, while platform usage varied significantly across gender and political lines. These findings provide insight into the digital behaviors and values that guided Gen Z’s media choices in the 2024 election and contribute to a growing understanding of how this generation navigates political information in a fragmented and polarized online ecosystem.Item Open Access Study of Kaon Production at Lower Energy Levels(2025) Carroll, LaurenIsaac Newton famously wrote, “It is inconceivable that inanimate brute matter should, without the mediation of something else which is not material, operate upon and affect other matter without mutual contact” (Newton, Isaac). This philosophical query ties into the mysteries that the Deep Underground Neutrino Experiment (DUNE) seeks to address. DUNE aims to explore fundamental questions such as the imbalance of matter and antimatter, supernova dynamics, and physics beyond the Standard Model. At its core, DUNE studies neutrinos, abundant subatomic particles with minimal mass and weak interactions, thus making them extremely difficult to detect. By examining how neutrinos interact and decay, DUNE aspires to deepen our understanding of the universe’s evolution and the underlying laws of physics. I am interested in looking at how DUNE’s project focuses on the cross sections of low-energy kaon particles, with the goal of improving their detection and calibration in liquid argon. Since DUNE is still under construction, I have been looking at how to use data from the prototype that will aid in identifying kaon decay and reducing confusion with similar particles. I am interested in learning more about refining kaon cross-section measurements to an accuracy of less than one percent and evaluating whether their detailed analysis significantly enhances particle research. Additionally, I have been researching how to combine the thin-slice and energy methods to produce a more accurate histogram of low-energy kaon production, thus contributing to DUNE’s broader mission of advancing particle physics.Item Open Access Brain health throughout cancer survivorship: the impacts of anti-cancer therapy on cerebrovascular regulation and pathology(2025) Scheuermann, BrittonCancer survivors have substantially greater risk of cardiovascular morbidity and mortality compared to the general population, including a 52% greater risk of heart failure and a 22% greater risk of stroke in some reports. The rates of development of chronic disease, even without immediately fatal endpoints, are similarly worrisome. Addressing both “hard” cardiovascular disease events and the incident development or exacerbation of chronic disease remains critical in the care of cancer survivors. This is even more true today with the increasingly rapid pace of progress in oncology – specifically, the introduction of immune checkpoint inhibitors. One of the primary concerns addressed in the present dissertation is neurotoxicity, experienced by many cancer survivors as a consequence of both the burden of cancer and due to adverse off-target effects of anti-cancer treatment. This neurotoxicity can manifest in a variety of ways, including cognitive decline, cerebral pathologies like encephalitis or reversible cerebral vasoconstriction syndrome, or in severe cases, stroke or intracranial hemorrhage. Despite the serious and harmful nature of these toxicities, investigations into overall brain health in cancer survivors are limited compared to the research dedicated to other organ systems. Therefore, in this dissertation, we present a series of four studies aimed at investigating cerebral and cerebrovascular health in cancer survivorship. Our first investigation was a systematic review and meta-analysis examining the associations between two local cerebrovascular regulatory functions (cerebrovascular reactivity, cerebral autoregulation) and one systemic vascular characteristic (arterial stiffness) with cerebral small vessel disease. Subsequently, we aimed to determine if there were impairments in cerebrovascular reactivity in cancer survivors compared to cancer-free controls. We then combined evidence from the first two studies to form a base of evidence suggesting that cancer survivors were likely to be at risk for cerebral small vessel disease. This led to our last two studies focused on a novel class of anti-cancer treatment, called immune checkpoint inhibitors (ICI). Our third study uses Mendelian randomization and human genetic information to explore relationships between exposure to ICI treatment and the risk of developing cerebral small vessel disease. Finally, our fourth study expands on the previous study’s findings with single-cell RNA-sequencing of vascular tissue from patients who did or did not receive ICI treatment. This patient tissue-derived information is combined with genomic and epigenetic analyses to investigate biological processes and pathways linking ICI exposure to cerebral small vessel disease, and to subsequently identify possible therapeutic options. It is our hope that this dissertation may provide insight into the cerebrovascular complications that exist in cancer survivorship, as well as their potential causes and consequences.Item Embargo Evaluating electrostatic spraying to improve food contact surface decontamination and produce safety and quality(2025) Kwamikorkor, ComfortThe demand for fresh produce highlights the need to maintain its safety, quality, and availability throughout the year. However, there has been an increase in foodborne outbreaks related to fresh produce due to microbial contamination. Escherichia coli O157, Salmonella spp., and Listeria monocytogenes are particularly known bacteria associated with multistate outbreaks, making them pathogens of concern. Bacterial contamination can occur at any stage of the food supply chain, from pre-harvest to post-harvest. Animals, soil, workers, and agricultural water can compromise the safety of fresh produce. This review provides an overview of the safety risks of fresh produce from the three common pathogens: Listeria monocytogenes, Salmonella spp., and Escherichia coli O157:H7. It also discusses cross-contamination from food contact surfaces to produce, sanitation practices in the fresh produce industry, electrostatic spraying as an alternative solution for surface decontamination, and future studies on its application. The primary goal of this chapter is to review sanitation practices in the fresh produce industry and to evaluate electrostatic spraying technology as an emerging solution for food contact surface decontamination, enhancing fresh produce safety and quality.Item Open Access A supportive and inclusive education that prepares: A deeper look at students with learning challenges and the support systems a Catholic, all-male, school provides for teachers to educate those students(2025) MacKenzie, SeanThere has been a great deal of research conducted examining how academic and social supports in schools, along with individualized accommodations, have helped to aid the education of students with learning challenges. There has also been research done in the response of Catholic schools to the education of students with learning challenges. This study examines the perspectives of teachers, in a private, Catholic, all-male, secondary school, and those teachers’ perceptions of the support they receive from their school when working with these students. It examines teachers’ perceptions about the access to resources, materials, and professional development that support students with learning challenges and how teachers’ differentiated instruction and non-academically related experiences provide academic and social support to all learners. It also specifically looks at how a private, Catholic, all-male, secondary school model impacts the perception of inclusion classrooms. This study concludes that inclusion is essential to Catholic education, and that private, Catholic, all-male, secondary schools have an obligation to have classrooms that include students with learning challenges. It also suggests differentiated instruction is beneficial to students with learning challenges and their educational experiences. Finally, it concludes though there are existing supports, such as educational personnel and teacher preparedness, there needs to be improvement in making these supports more effective and available for the teachers themselves.Item Open Access Irisin as a mediator of the positive relationship between exercise and the brain in health and Alzheimer’s disease(2025) White, ZacharyAlzheimer’s disease (AD) is a neurodegenerative disease impacting over 6 million Americans with cases projected to increase to over 14 million by 2060. The AD process creates difficulty completing everyday tasks or conversations, and ultimately, progresses to disrupt the most basic bodily functions and require full-time caretaking. While disease modifying therapy remains elusive, reducing the incidence of AD is crucial in order to mitigate the projected increase in cases. Exercise has emerged as an effective strategy to promote brain health in late adulthood and to protect against the onset of AD. Exercise opposes several disease processes including cognitive dysfunction, amyloid beta aggregation, tau phosphorylation, and deficits in hippocampal volume, mitochondrial function, cerebral blood flow, and neurogenesis through various pathways including the systemic release of exerkines. The exerkine irisin is an important mediator of the beneficial relationship between exercise and the brain. Previous work administering irisin therapeutically to healthy and preclinical AD mice has demonstrated irisin to replicate multiple exercise-induced effects in the brain and protect against AD-induced deficits. Although irisin is suggested as a promising strategy to promote brain health in late adulthood, our understanding of irisin signaling and irisin-induced protection against AD remains incomplete. Through behavioral testing and protein analyses in healthy and transgenic preclinical AD rats, this dissertation assessed the physiological role of irisin and the translatability of irisin-induced protection against AD. In our first investigation (chapter 2), we found that a single administration of irisin was sufficient for activation of irisin-hippocampus signaling. In our second investigation (chapter 3), we found that the cofactor extracellular heat shock protein 90 alpha, which had been previously demonstrated to be required for irisin signaling in adipose tissue, is not necessary for irisin-receptor interaction in the brain. In our third investigation (chapter 4), we aimed to investigate AD phenotype in transgenic rats following an adenovirus intervention previously demonstrated to stimulate irisin production in AD mice. We found no increase in irisin levels or irisin signaling in our transgenic AD rats following vector administration. Taken together, these studies suggest irisin as an important, physiologically relevant promoter of brain health, however, the translatability of irisin-mediated neuroprotection in aged transgenic AD rats remains untested.Item Open Access Integrated post-harvest management of stored product insects in sorghum: Effects of kernel properties, temperature, and grain protectant efficacy(2025) Liba, TannerSorghum bicolor, commonly known as sorghum, is one of the five most economically important cereal grains in the world. In the United States, it is used extensively for livestock feed and ethanol production, while globally, it serves as a staple food for >500 million people. Its value lies in part in its exceptional drought tolerance, enabling it to perform in regions where other cereals often fail. This resilience is largely due to sorghum’s genetic flexibility, which allows breeders to improve both agronomic performance and grain quality. Through targeted breeding, traits such as drought resistance, kernel hardness, protein content, starch composition, and kernel size can be selected, influencing sorghum’s suitability for various end uses. As global temperatures rise and water availability becomes increasingly scarce, sorghum’s role as a climate-resilient crop is expected to grow. However, post-harvest storage remains a critical challenge as arthropod pests reduce grain quality and quantity through direct feeding and contamination with frass, exuviae, webbing, and associated microbial growth. Key pest species, Rhyzopertha dominica, Sitophilus oryzae, Plodia interpunctella, and Prostephanus truncatus, cause substantial annual losses worldwide. To mitigate these losses during bulk storage, strategies such as sanitation, grain aeration, fumigation and the use of grain protectants are commonly employed. While the efficacy of grain protectants has been well studied in other cereal crops like wheat, rice, and maize, relatively little is known about their performance on sorghum. Integrated Pest Management (IPM) emphasizes the importance of understanding how grain traits, storage conditions, and pest biology interact to influence both stored product susceptibility and grain protectant efficacy. This research applied IPM principles to evaluate post-harvest protection of stored sorghum. First, we assessed the susceptibility of sorghum varieties differing in kernel hardness and protein content to infestation by R. dominica and S. oryzae. Results showed that both kernel hardness and protein content significantly influenced susceptibility to S. oryzae, while only protein content affected susceptibility to R. dominica. Second, we examined how storage temperature (22, 27, and 32°C) impacted the efficacy of four commercially available grain protectants (Diacon® IGR, EverGreen®, Gravista®, and Sensat™) against R. dominica, S. oryzae, and P. interpunctella, as well as its influence on pest development. We found that temperature had a significant effect on the grain protectant efficacy, with some formulations exhibiting a decrease or increase in their ability to mitigate infestation depending on environmental conditions. For instance, we found that insecticide formulations containing pyrethrins or pyrethroids performed better than cooler temperatures in terms of adult mortality and mitigating progeny and further damage, whereas there was an observed decrease in efficacy when temperatures were higher. The opposite trend was observed for the active ingredient spinosad, which saw a higher rate of efficacy at warmer temperatures and less efficacy at cooler temperatures. Overall, species development was faster at higher temperatures regardless of treatment. Third, we evaluated the long-term efficacy of the same grain protectants over a 28-week simulated storage period against R. dominica and S. oryzae. The grain protectant performance remained consistent over time, with high rates of adult mortality, low progeny, and lower levels of product damage observed for all protectants against R. dominica during the course of the experiment. However, the declining moisture content of the stored sorghum over time was a major contributing factor affecting infestation levels. Furthermore, R. dominica showed a higher degree of susceptibility to treated sorghum compared to S. oryzae. The results of these three studies support the need for the development of a sorghum-specific IPM strategies. The factors of grain varietal traits, grain protectant formulation, and storage environments all play a pivotal role in sorghum’s susceptibility to infestation of four primary species that infest bulk grain. Furthermore, this research highlights the importance of understanding the target-species biology and ecology when employing IPM strategies. Ultimately, this research lays the groundwork for understanding the challenges and opportunities for targeted post-harvest IPM practices in the United States and internationally.Item Open Access Policies and best practices in addressing digital equity gaps: A multisite case study of leaders within a community college system(2025) Calfa, VickiThis qualitative multisite case study examined the policies and best practices adopted by a large, urban community college system to recognize and address digital equity gaps. Guided by Feenberg’s critical theory of technology and Resta and Laferrière’s five dimensions of digital equity, the study explored how leaders operationalized asset-based approaches to support students, particularly those from low-income, first-generation, and underrepresented backgrounds. Data were collected through document analysis and semi-structured interviews with 21 leaders representing executive administration, faculty, student services, and information technology. Coding and thematic analysis revealed six overarching themes: (a) digital equity practices guided by policies, (b) finding and meeting needs, (c) connecting students to resources, (d) technology as a tool to increase access, (e) student focused multidisciplinary decision making, and (f) lessons learned from the COVID 19 global pandemic. Seven promising practices emerged, including a laptop loan program, a PC repair lab, embedded success coaches, mobile success librarians, community-based technology courses, community partnerships for technology access, and a digital equity rubric for course design. Findings indicated that intentional, policy aligned practices, coupled with cross functional collaboration, enhanced students’ access to technology and related support.Item Open Access Optimizing feedlot placement weights using simulation-based mathematical programming(2025) Stika, MaccoyThis thesis develops a mathematical programming model to determine the optimal feeder placement weight that maximizes net returns in commercial feedlot operations. Feedlot profitability is affected by numerous biological and economic variables that include feed efficiency, yardage costs, health risks, mortality, feeder cattle purchase prices, and carcass-based revenue. Linear programming has been implemented within the industry before, but linear programming is rarely used to directly model how placement weight influences profitability over a defined feeding period. This study addresses that gap by integrating a flexible mathematical framework with real-world data and biologically informed performance data. The model simulates feeding outcomes across a range of initial weights while incorporating price slides, dressing percentage, feed-to-gain efficiency, mortality rates, and culling probabilities. Feeder cattle prices and grid-based carcass discounts are included to reflect the real-world market profits that feedlots could experience. The results of this analysis provide feedlot operators with a decision-support tool that can capture the trade-offs between animal growth and economic constraints. The results demonstrate how market-based carcass valuation can incentivize particular feeding durations. By offering a replicable and data driven optimization tool, this thesis contributes practical insights to feedlot decision-making and expands the agricultural economic literature on production modeling.Item Open Access Evaluating virtually: A closer look at university supervisor/preservice teacher relationships during asynchronous virtual evaluations.(2025) Callanan, VanessaPreservice teaching experiences are the final stage of perspective teachers' education and often, supervisors at the university level are charged with completing their evaluations. During this stage, it is critical that university supervisors provide insightful input and feedback regarding the performances of the preservice educators, as through this process, burgeoning educators may improve their pedagogy, refine their classroom management skills, and gain valuable insights in the field. While this practice has existed for decades, the emergence and prevalence of new technologies has allowed for a different type of evaluation: asynchronous virtual observations. This study expands on the body of research that exists on the training of university supervisors to adapt these asynchronous virtual evaluations, and explores best practices, rapport-building, and development of valuable feedback strategies when using online video software. As a result of this study, three insights emerged regarding the use of asynchronous virtual evaluations: the importance of initial and sustained communication, the use of constructive, specific feedback strategies, and the perceived inauthenticity of recorded classroom lessons. Findings from this study indicate that while virtual evaluations tools offer a great deal of flexibility for schools of education, there is much refinement that needs to be made to fully maximize the benefits for preservice educators and university supervisors. Furthermore, when viewed through the lens of a dual-dialogic theoretical framework, the findings of this study suggest that additional steps be taken to enhance the communicative potential of university supervisors, including the use of cohorts to help increase understanding, compassion, and empathy. This dissertation concludes with a set of implications, suggestions, and areas in which this topic may be studied further as virtual evaluations continue to grow in use and scope.Item Open Access Variation in runoff generation and concentration-discharge behavior in three variably encroached grassland watersheds(2025) Pruitt, JohnnyDisplacement of grasses by woody plants, a phenomenon known as woody encroachment, is occurring in grasslands worldwide. Previous studies indicate woody encroachment has the ability to alter runoff generation, increase soil porosity and permeability, decrease soil water residence time, decrease streamflow, and even accelerate soil drying. However, little is understood about the consequences all of these processes have on streamflow sources and composition. To fill this knowledge gap, we deployed high-frequency sampling of stream water during seven different rainstorms during the 2024 water year from three variably-encroached watersheds hosting headwater streams at Konza Prairie Biological Station, a native tallgrass prairie in northeastern Kansas, USA. We also examined streamflow and precipitation records for two time periods, one before widespread encroachment occurred in any of the watersheds (1987-1990) and the other more recently (2020-2023), after significant encroachment. Woody encroachment varies between the watersheds primarily due to differences in the frequency of fire treatment. Upland and riparian woody plant coverage is 6% and 45%, respectively in the annually burned watershed, 20% and 70%, respectively in the biennially burned watershed, and 28% and 74%, respectively in the quadrennially burned watershed. Isotope hydrograph separation analysis based on stream and precipitation stable isotope compositions did not reveal any clear differences in amounts of runoff generation between watersheds. Most of the storms that we sampled were not large enough to cause large changes in stream water isotope compositions. However, our analysis of stream discharge and precipitation records indicates that encroachment is decreasing the sensitivity of streamflow to storms. We examined discharge-precipitation relationships by normalizing the change in streamflow (ΔQ) to precipitation event size (P) and watershed area (A). Results show that ΔQ/P/A values were higher in 2020-2023 than 1987-1990 for all three watersheds, but the difference was greatest for the least encroached watershed, potentially reflecting impacts of climate change on storm intensity coupled with changes in soil permeability as a result of encroachment. Moreover, an analysis of concentration-discharge behavior for stream solutes suggests that encroachment is altering stream composition. Both geogenic and biogenic solutes were more chemodynamic in the least encroached watershed compared to the more encroached watersheds. Additionally, the least encroached had lower pH and higher concentrations of alkalinity and bedrock weathering products, potential in response to encroachment-driven differences in the amount and depth of mineral weathering between watersheds. Taken together, the findings of this study suggest that encroachment is impacting headwater streams not only in terms of their response to storms but also in terms of stream water composition, which can have significant downstream implications for flood risks and water quality.Item Open Access The Global Ammonia Industry in Transition: Global Market Trends, Price Interdependencies, and Techno-Economic Feasibility of Green Ammonia(2025) Ofori-Bah, Catherine ObiribeaAmmonia is one of the most produced chemicals in the world, playing an essential role in global agriculture and industry. Traditionally produced using energy-intensive methods that are reliant on fossil fuels, ammonia’s market dynamics are influenced by energy prices and sustainability concerns. Additionally, concerns about a growing global population emphasized the importance of ammonia in crop production to meet global food demand. This dissertation explores the global ammonia market structure, analyzes the interdependencies between natural gas, ammonia, and agricultural commodity prices, and studies the techno-economic feasibility of local wind-powered ammonia production in Western Kansas over a 25-year lifespan. A desk review was used to explore the global ammonia market. Meanwhile, a Vector Error Correction Model (VECM) was used in the analysis of commodity price data from 2014 to 2024 to assess price transmissions. Subsequently, this dissertation reviewed the technologies required for wind-powered ammonia production and their associated costs. It also evaluated Net Present Value (NPV), Profitability Index (PI), Internal Rate of Return (IRR), Payback Period (PBP), and Return on Investment (ROI) for green ammonia production via four electrolysis technologies (i.e., alkaline water electrolysis (AWE), proton exchange membrane/polymer-electrolyte membrane (PEM), Anion exchange membrane (AEM), and Solid Oxide Electrolysis Cell (SOEC)) and four ammonia price scenarios (i.e. forecasted price series, average price from 2014 to 2021 ($647.81/MT), average price from 2022 to 2024 ($1160.78/MT), and the highest ammonia price ($1770.42/MT)). Sensitivity analysis was conducted to examine the impact of changes in electrolyzer efficiency and ammonia market prices on NPV. Market analysis showed an increasing interest in transitioning from fossil-based ammonia to green ammonia. Furthermore, the results show that there is a cointegrating relationship between natural gas and ammonia prices, as well as ammonia prices and agricultural commodities. The technoeconomic feasibility studies revealed that under current cost and efficiency levels, the project is not economically feasible. Green ammonia production is economically feasible under all wind-electrolyzer combinations at an average price of $1160.78/MT and at the fixed highest price scenario. Sensitivity analyses revealed that green ammonia production can become competitive with conventional production with increased electrolyzer efficiencies and unusually high prices for conventional ammonia. This dissertation provides an integrated view of the ammonia market, price, and production dynamics, offering insights for navigating a transition from conventional ammonia production to green ammonia production. This research further contributes to the literature on renewable-based pathways for industrial decarbonization.Item Open Access A novel Monte-Carlo based method of calculating mean transit time through voxelized biological organs(2025) Ahmad, Md IstiakCapillary transit time, defined as the time required for blood to traverse the microvascular network, is a cornerstone parameter in the study of hemodynamics. The study of capillary transit time, the foundation of which was laid by August Krogh in his seminal 1919 work, has come a long way since its advent. At present, capillary transit time analysis is being used to assess microvascular function and tissue oxygenation in conditions like stroke, tumors, and neurodegenerative diseases, guiding treatment strategies in radiotherapy and thrombolysis. It also helps optimize drug delivery by revealing how blood flow heterogeneity affects therapeutic agent distribution and retention in target tissues. With the advancement of blood flow simulation using computational human phantoms (CHP), a potential novel use of capillary transit time analysis in the field of internal and external dosimetry has arisen, where it may be used to predict the distribution of dose imparted by the radiophermaceuticals and the distribution of irradiated white blood cells in tumors. Various experimental and mathematical methods have been developed over the years to measure and predict capillary transit time. However, these models lack applicability in particle tracing applications. On the other hand, existing Monte-Carlo particle tracing codes lack the functionality of tracing particles inside vasculatures. Hence, the aim of the present work is to develop a path tracing algorithm that follows blood flow in the vasculature, including the capillary bed, using the principles of Monte-Carlo simulation and existing blood flow framework found in contemporary literature (The VoM-PhyS framework) to facilitate the calculation of mean transit time. One of the main challenges in developing a path tracing framework is finding a suitable probability distribution of possible next steps, based on which each step of the random walk of the particles is chosen. In the present study, this probability distribution is derived based on the outgoing flow rate at a particular node. Flow rate is calculated from governing equations, including Hagen-Poiseuille and Darcy’s equation of porous media, depending on particle location in the network. Using this probability distribution, random particle tracks are generated for increasing particle numbers and the associated elapsed-times are calculated. Variability of the elapsed time resulting from variation in the particle’s velocity considering its position with respect to the centerline of arterial and venous vessels is accommodated in this framework, as well. In the VoM-PhyS model, blood takes an instantaneous jump from the terminal of the segmentable vessels to a nearby tissue voxel within a specified sphere of influence. A method of estimating the time elapsed in this jump was also developed and implemented. The transit time distributions and the mean transit times were derived from these data. It was found that the distribution of mean transit time follows a gamma-variate distribution, which flattens with increasing sphere of influence, i.e., the variation in times increases. It was also found that the peak of the distributions shifts to increasing time values and the mean transit time increases with increasing sphere of influence. Finally, results of various statistical tests are presented to verify the statistical significance of the data generated using the proposed framework.
