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 Intermediate wheatgrass (Thinopyrum intermedium) and grain sorghum as novel, sustainable ingredients in extruded precooked pasta and expanded snacks – Life cycle assessment, physicochemical properties and product quality(2024) Rivera, Julia; Alavi, SajidThis thesis explores the potential of Intermediate Wheatgrass (IWG) and sorghum as sustainable alternatives to conventional grains in the production of extruded precooked pasta and expanded snacks, while evaluating their environmental impacts through a life cycle assessment (LCA). IWG, with its deep root system, enhances soil health and carbon sequestration, addressing challenges like soil erosion and high water usage. Sorghum offers sustainability benefits in water-scarce regions, with comparable or improved product performance. Six pasta formulations incorporating wheat, IWG, and sorghum were assessed for functionality and cooking performance. Pasta made solely from wheat exhibited the highest cooking loss at 5.6%, while IWG pasta had 3.9%, and sorghum pasta achieved the lowest cooking loss at 1.9%. RVA analysis revealed wheat’s higher peak viscosity (1064 cP) compared to sorghum (979 cP) and IWG (443 cP), suggesting differences in starch binding and degradation that influenced cooking outcomes. The study also examined the properties of IWG and sorghum in expanded snack production. IWG snacks exhibited the highest density at 0.28 g/cm³ compared to corn (0.12 g/cm³) and sorghum (0.14 g/cm³), indicating potential differences in textural outcomes. Expansion ratios revealed that sorghum achieved 10.22, significantly higher than IWG's 5.80, while corn reached 10.58. In terms of hardness, IWG snacks measured 22.95 kg, notably harder than corn (15.54 kg) and sorghum (12.96 kg). These findings highlight opportunities to balance texture and sustainability in snack formulations. LCA results showed sorghum with the lowest Global Warming Potential (GWP) at 0.09 kg CO2 eq/kg for snacks and 0.11 kg CO2 eq/kg for pasta. IWG exhibited higher direct GWP (0.31 kg CO2 eq/kg for pasta) but transformed into a carbon sink when considering carbon sequestration and straw allocation, reducing net GWP to -0.7 kg CO2 eq/kg. These findings underscore IWG’s potential to offset emissions through soil organic carbon sequestration (42 tons C/hectare), while sorghum offers low emissions with favorable product properties. This research highlights the environmental and functional advantages of integrating IWG and sorghum into food systems, contributing to more sustainable agricultural practices and product development.Item Open Access Dimuon production in the MicroBooNE detector(2025) Martinez Figueroa, Norman AmilkarThis analysis studies the production of the rare signal with two muons (dimuon) in the final state at µB using the Booster Neutrino Beam (BNB) as source of neutrino interactions. The main background source for the dimuon signal are pions. Differentiating muons and pions has been challenging at µB because the tracks left by these particles are almost identical. This analysis faces this problem using a supervised classifier algorithm called boosted decision tree (BDT). A Monte Carlo simulation (MC) enhanced dimuon signal sample was produced to train a BDT capable of recognizing this signal. A set of variables that show some discrimination characteristics was used to perform the training. A MC neutrino interaction simulation sample was used to estimate the background. Estimations of dimuon production in real data samples were made for different cases. Additionally, an analysis of the systematic uncertainties, fake data studies, and BDT performance checks were obtained.Item Open Access Interactions of antioxidants and phenoloxidase reactions in Manduca sexta hemolymph(2025) Morabito, SequoyahMelanization is an important component of the insect innate immune response. Melanization occurs when an insect is exposed to pathogens such as bacteria or fungi. Phenoloxidase (PO) is a key enzyme in the synthesis of melanin. Recognition of bacterial peptidoglycan initiates a cascade of serine proteases, which activates PO. PO then hydroxylates tyrosine and oxidizes DOPA and dopamine, derived from tyrosine, to ortho-quinones. These participate in redox reactions that finally result in synthesizing melanin. Ortho-quinone formation and the redox reactions produce reactive oxygen species (ROS), which may help in eliminating pathogens but may also be harmful to the host insect. Insects may regulate oxidative damage to themselves. In this study, PO in hemolymph was activated similarly when plasma was exposed to either Lys type or DAP type bacterial peptidoglycans. However, lower amounts of Lys type peptidoglycans were able to stimulate PO more when compared to DAP type peptidoglycans. Colorimetric measurements revealed that M. sexta plasma contains a high concentration of ascorbate that significantly decreases when plasma PO is stimulated with peptidoglycan. Unexpectedly, PO activation also resulted in an increase in the total antioxidant capacity in plasma, which may be caused by the increased concentrations of DOPA produced during the melanization response, since DOPA can act as a reducing agent. Mass spectrometry, performed on M. sexta whole hemolymph and plasma, was used to reproducibly determine concentrations of total thiols, total reduced thiols, reduced glutathione, oxidized glutathione, cysteine, cystine, and glutathione-ss-cysteine, revealing that antioxidants are predominantly located in plasma and not hemocytes. Mass spectrometry was used to determine changes in concentrations of the following antioxidants and metabolites in plasma after stimulation of PO activation with peptidoglycan: total reduced thiols, total oxidized thiols, percent oxidized thiols, total glutathione, total cysteine, total homocysteine, total cysteine-glutathione, free glutathione, oxidized glutathione (GSSG), free cysteine, cystine, glutathione-ss-cysteine, ascorbate, dehydroascorbate, tyrosine, DOPA, dopamine, and tyrosine glucoside. Stimulated plasma had a significant decrease in concentrations of glutathione, cysteine, ascorbate, and tyrosine. Concentrations of DOPA significantly increased in stimulated plasma samples while the concentration of dopamine did not change, demonstrating the hydroxylation of tyrosine and suggesting that DOPA is the predominant diphenol used during melanization. These results show that the redox environment in M. sexta plasma is highly reducing and suggests that shifts in redox potentials and regulation of the redox environment may not only regulate PO activity but may also prevent oxidative damage to the host.Item Embargo Development of processing technologies for gluten-free and plant-based food applications(2024) Pulivarthi, Manoj KumarThe increasing demand for gluten-free and plant-based products has driven the need for high-quality alternative ingredients that offer both functionality and sustainability. Sorghum and pulses like yellow peas and red lentils are promising sources, requiring advanced processing techniques to optimize their use in diverse food applications. This thesis investigates milling and protein fractionation processes to enhance the functionality and application potential of sorghum- and pulse-based flours and protein fractions. A detailed review of current research on dry fractionation for producing functional, protein-rich ingredients highlights its sustainable and eco-friendly advantages as an alternative to intensive wet fractionation. In Chapter 3, a roller milling technique combined with ultrasound tempering (UST) was developed to produce high-quality white and sumac sorghum flours for gluten-free applications. UST significantly impacted milling yield, particle size, starch damage, and ash content. Notably, the milling yield of white sorghum increased from 73.3% (control) to 76.6–78.2% with treatment durations. A 1-minute UST enabled efficient bran separation, lowering ash content to 0.87% in white sorghum and 0.69% in red-tannin sorghum, compared to 1.05% and 1.4% in controls. This optimized milling approach proved suitable for both sorghum varieties, enhancing flour quality regardless of physical property differences. Chapter 4 examined the rheological properties and baking performance of UST-treated white and sumac sorghum flours. Mixolab and rapid visco analyzer (RVA) results demonstrated enhanced starch gelatinization and retrogradation, particularly in sumac sorghum. UST improved bread quality by reducing hardness and enhancing crumb structure, with the most notable improvements in sumac sorghum. While cookie quality was unaffected by UST time, both sorghum flours showed good cookie baking performance. In Chapter 5, roller milling settings were optimized to produce dehulled yellow pea and red lentil flours of various particle sizes (small, medium, and large) with minimal nutritional differences. The geometric mean diameters for red lentil flours were 56.05 μm (small), 67.01 μm (medium), and 97.17 μm (large), while yellow pea flours ranged from 41.38 μm to 98.31 μm. Starch damage increased with smaller particle sizes due to intensified milling, impacting flowability and suggesting roller milling as an effective technique for producing flours with varied functional applications. The final study compared dry and wet fractionation methods for producing protein-rich red lentil fractions. Air classification, a dry fractionation method, achieved up to 60.53% protein content with a recovery of 19.52%. Optimal protein purity and yield (57.84% protein at 6,000 rpm with 29.96% recovery) were achieved with a 22 μm cut point. Wet fractionation produced protein isolates with up to 89.23% protein content, while the mild-alkaline red lentil concentrate reached 64.24%. Functional testing showed the wet-extracted isolate excelled in emulsifying capacity (EC), water absorption (WAC), and oil absorption (OAC), while dry-fractionated proteins offered enhanced foaming, solubility, and gelling properties, preserving native functionality. These findings provide sustainable solutions for gluten-free baking and plant protein enrichment, supporting the development of high-quality, nutritionally enriched food ingredients to meet growing consumer and industry demands.Item Open Access Probiotics in feedlot cattle: Implications for reducing liver abscess pathogens(2025) Moe, MaggieLiver abscesses are a significant health and economic issue in feedlot cattle, predominantly caused by Fusobacterium necrophorum, Trueperella pyogenes, and Salmonella enterica. These abscesses commonly result from ruminal acidosis or rumenitis associated with high-grain diets. While liver abscesses have traditionally been controlled with in-feed antimicrobials like tylosin and chlortetracycline, increasing concern over antimicrobial resistance drives the need for alternative therapies. This study aimed to investigate the potential of lactic acid bacteria (LAB) isolated from liver-abscess-free cattle as natural inhibitors of liver abscess-causing pathogens. Between 2 beef processing plants, ruminal content samples from 56 cattle were collected originating from 28 feedlots. From the samples collected, 560 LAB isolates were obtained, and broth cultures were separated into two cell-free aliquots: one with neutralized pH and the other remaining unaltered. Isolates were then screened for antimicrobial activity against the target liver abscess pathogens using agar-well diffusion assays. Results indicated that non-pH-adjusted LAB supernatants exhibited zones of inhibition for all three pathogens, with F. necrophorum showing the greatest inhibition and highest isolate sensitivity. However, pH-adjusted LAB supernatants displayed no antimicrobial activity, suggesting pH plays a significant role in the inhibitory effects observed. In total, 14 LAB isolates exhibited broad-spectrum inhibition across all pathogens, although repeated trials showed variability between experiments, highlighting the potential influence of LAB supernatant composition and culture conditions. Our findings suggest that ruminal LAB may exhibit innate antimicrobial effects against liver abscess pathogens, with Lactobacillus species showing potential for use in probiotics products for cattle on high-grain diets. Further research is needed to characterize these LAB isolates, assess their consistency and efficacy, and determine suitability as direct-fed microbial species for livestock production. This study highlights the potential of probiotics as viable substitutes to traditional antimicrobials for managing liver abscesses in feedlot cattle.Item Embargo Study of the PD-1 expression in lung carcinoma cells and T lymphoblasts by Euglena gracilis water extract(2024) DeVader, SarahLung cancer is the leading cause of cancer related deaths in the United States. Natural products are a diverse source of anticancer compounds. Euglena gracilis (E. gracilis) is a unicellular freshwater green alga rich in nutrients that is used as a dietary supplement. It has been studied for its many properties, including anti-inflammatory, antiviral, and antitumoral. We have been investigating the preventative effects of E. gracilis against lung cancer development. Our previous studies demonstrate water extract from E. gracilis (EWE) possesses anti-cancer activity against lung carcinomas and stimulates T-cell cytotoxicity against lung cancer cells. However, it is unknown how EWE directly attenuates the growth of lung carcinoma cells and directly stimulates T cells, and what component(s) within EWE are responsible for these biological effects. In the current study, we investigated the relationship between EWE and the mRNA expression of PD-1 in lung carcinoma cells and T cells. Orally administered EWE in an orthotopic lung cancer syngeneic mouse model was revealed to increase the expression of PD-1 and PD-L1 in tumor-bearing mouse lungs, which was correlated with a decrease in tumor weights in the mice. In vitro, EWE was found to increase the mRNA expression of PD-1 and PD-L1 in both murine Lewis lung carcinoma (LLC) cells and murine splenocytes, and EWE also increased the mRNA expression of PD-1 and granzyme B in human Jurkat T lymphoblasts. Using the EWE-induced stimulation of these proteins as assay tools, the bioactive compound in EWE was purified by FPLC with a size exclusion column. Three specific fractions were found to increase the mRNA expression of PD-1 and PD-L1 in LLC cells and the mRNA expression of PD-1 and granzyme B in Jurkat cells. The FPLC fraction which showed highest bioactivity was further fractionated by C18 reverse phase HPLC. The resulting HPLC fraction that increased the expression of PD-1 in LLC cells was subjected to the structural analysis by liquid chromatography mass spectroscopy and nuclear magnetic resonance, which is currently underway. These results suggest that there is a relationship between the EWE-induced attenuation of lung tumor growth and the EWE-induced increased PD-1 expression, and that EWE treatment may enhance its therapeutic efficacy by stimulating antitumor immunity in lung cancer. The PD-1 stimulator present in EWE was preserved throughout fractionation with FPLC and HPLC in tandem, and, once identified, could provide clear insights into the mechanisms by which EWE achieves these biological effects.Item Open Access Field-scale quantification of methane and nitrous oxide agricultural emissions using micrometeorological approaches(2025) Weerasekara, ChinthakaMethane (CH₄) and nitrous oxide (N₂O) emissions from agricultural systems are significant contributors to global greenhouse gas (GHG) emissions, and accurate quantification of these emissions is essential for improving GHG inventories and evaluating mitigation strategies. This research employs the eddy covariance (EC) technique, artificial neural networks (ANN), and footprint analysis to address key challenges, such as spatial variability, data gaps, and footprint limitations, in measuring GHG emissions in dynamic agricultural environments. The objectives of this study were to: 1) assess the performance of the EC technique for measuring N₂O and CH₄ fluxes in agricultural systems; 2) develop ANN models to fill gaps in N₂O flux data; and 3) evaluate CH₄ emission rates from grazing systems using EC and footprint models. The first study focused on N₂O emissions measured using the EC technique in two contrasting agricultural environments: a cattle feedlot and a winter wheat field. In the cattle feedlot, average N₂O fluxes were low (0.0062 μ mol m⁻² s⁻¹) during winter, with emission spikes that were not consistently linked to precipitation or temperature changes due to frozen soil conditions. In contrast, the winter wheat field exhibited higher variability, with emission rates peaking at 0.03 μ mol m⁻² s⁻¹ during warm, moist periods following nitrogen fertilization and rainfall. Footprint analysis in the cattle feedlot revealed that up to 70% of the measured flux contributions came from outside the feedlot boundary, driven by manure runoff and off-site sources. In the winter wheat field, N₂O fluxes were more evenly distributed within the footprint and closely associated with fertilizer applications and subsequent precipitation events. These findings demonstrate the necessity of continuous high-frequency measurements to capture the full temporal and spatial variability of N₂O fluxes in agricultural systems. The second study applied artificial neural networks (ANN) to fill data gaps in N₂O flux measurements at winter wheat fields. Data gaps, caused by equipment malfunctions, low-turbulence conditions, and extreme weather events, can significantly affect the accuracy of long-term flux data. The ANN models were trained using environmental variables, such as soil moisture, temperature, and wind speed, and demonstrated strong performance, achieving a coefficient of determination (R² > 0.85) between predicted and observed fluxes. At the winter wheat field, the ANN model successfully reconstructed missing flux data due to cold weather and sensor failures and filled gaps during elevated N₂O emissions following fertilization. These results highlight the importance of using advanced gap-filling techniques, such as ANN, to maintain the integrity of long-term GHG datasets, particularly in complex agricultural systems. The third study focused on quantifying CH₄ emissions from grazing systems using the eddy covariance (EC) technique in combination with flux scaling based on footprint analysis. Controlled CH₄ release experiments were conducted to simulate emissions from a small herd of cattle, allowing for the assessment of the EC system's accuracy in estimating CH₄ fluxes. The results revealed that CH₄ fluxes were consistently underestimated, with the calculated emission rates clustering around 30% of the actual release rate. This underestimation was linked to the footprint model’s difficulty in fully capturing contributions from the source area, especially at lower fetch percentages. Increasing the fetch to 90% improved source coverage but introduced instability and errors. These findings emphasize the need for more accurate footprint models to account for varying wind conditions and terrain complexities in grazing environments. The integration of these studies underscores the importance of continuous high-frequency measurements in capturing the variability of N₂O and CH₄ emissions in agricultural systems. Due to uncontrollable factors such as equipment failures and adverse weather conditions, data gaps are inevitable, making gap-filling techniques like ANN crucial for ensuring data continuity. Footprint analysis further improves the accuracy of emission estimates by addressing spatial variability in emission sources, particularly in grazing systems. This research advances the understanding of GHG emissions from livestock and crop production systems, contributing to more accurate emission inventories and the development of effective mitigation strategies in agriculture.Item Open Access Evaluating economic impacts of marketing agreements in a differentiated U.S. beef industry(2025) Doumit, KatherineUnderstanding the impact of value-based pricing methods on beef cattle quality, as well as differentiating the impact of high- and low-quality beef across the supply chain, has become increasingly important with the rise in high-quality cattle over the past decade. The shift towards alternative marketing agreements (AMAs) has heightened concerns over market transparency and price discovery, emphasizing the need to understand the long-term impact of these marketing methods on the industry. This thesis first evaluates the influence of value-based pricing methods, specifically formula and negotiated grid pricing, on the percentage of cattle grading Choice and Prime. Using a quality index model, economic factors impacting cattle quality grading are evaluated. Findings indicate that increased use of AMAs has substantially shifted the quality dynamics of the beef industry, with a 0.94% increase in cattle grading Choice for every 1% increase in formula and grid priced cattle. Building on these results, the economic impacts of supply shifts in high-quality beef are assessed across four levels of the beef supply chain – retail, wholesale, slaughter, farm – under scenarios of reduced formula and grid pricing. Since the dramatic improvement in beef quality and shift in fed cattle marketing methods, a study analyzing the impacts on a differentiated market has not been completed. This research uses an equilibrium displacement model to evaluate the impacts of a negative shock to high-quality wholesale beef supply resulting from an increased use of cash negotiated trade, as proposed policy in policy discussions. Findings indicate an increase in price and decrease quantity for high-quality wholesale and retail beef while price declines and quantity increases for low-quality wholesale and retail beef. Aggregate slaughter and feeder cattle producers experience declines in both price and quantity. Findings from this study show a strong association between formula and grid pricing methods and high-quality beef production. Policies mandating increased cash-negotiated trade, which would diminish the use of formula and grid pricing, are shown to reduce demand for cattle from producers, ultimately leading to lower prices received by them. By adopting a heterogenous market perspective, this study highlights the differential impacts of AMAs, providing stakeholders with crucial insights into the valuation and policy implications of AMAs in the evolving beef industry.Item Open Access A Wire Indent Profiling System for the Assessment of Crosstie Bond and Splitting Propensity(2025) Robertson, AaronConcrete railroad ties represent a critical component of transportation infrastructure. A majority of concrete crossties are created from prestressed concrete, relying on the interaction between steel tendons, or strands, and the concrete to produce prestressing force in the ties. Inadequate prestressing force or splitting significantly reduces the service life or load bearing capacity of the crossties. Smooth steel tendons do not provide reserve capacity to prestressed members, as any instantiated crack cannot be arrested; therefore, indentations are added to the steel tendons to provide reserve capacity and reduce the distance over which the prestressing force is transferred from the steel tendon to the concrete, defined as the transfer length. The geometry of these indented features significantly impacts the transfer length and splitting propensity of manufactured concrete railroad ties. Indentation geometry has been shown to have a direct influence on the performance of prestressed members. Thus, it is important to measure critical indent features to ensure that indents are being formed to the right tolerances and provide the desired wire-concrete performance. However, the measurement of such features has proven challenging in practice. Certain standards, namely ASTM A881, outline indent features to measure for quality control for wires of a given size, but fall short of describing how or where measurements will be performed. Such measurements are often done manually, suffer from poor accuracy, and are time consuming. The time-consuming nature of the measurements makes it impractical to sample enough indents to adequately statistically characterize the manufacturing process. Most importantly, the current standards do not identify which features, or combinations of features, contribute to, or reduce, wire-concrete bond performance. It is possible for indented wires to pass the requirements of the measurement standards but fail to produce desirable wire-concrete performance; this is often only discovered after the crossties have been manufactured. This research addresses the shortcomings of the current measurement standards, identifies which indent features most significantly contribute to wire-concrete performance, and outlines the development of an Indent Profiling System that is capable of extracting all important indent features. An automated, high resolution, non-contact measurement system was created and used to measure dozens of wires from modern industry, historical crossties, and lab specimens with well-defined geometry. This system measures all unique indents formed by a complete revolution of the indent rollers, providing statistically relevant sample sizes that were previously impossible using manual measurements. To identify which wire features, or combinations of features, correlate strongly with performance hundreds of prestressed prisms were created as part of a larger FRA project titled “Developing Qualification Tests to Ensure Proper Selection and Interaction of Pretensioned Concrete Railroad Tie Materials”. These prisms used the same wires that were scanned by the Indent Profiling System and were created with a variety of concrete covers, release strengths, and aggregates to assess wire-concrete performance. The known indent geometry provided by the Indent Profiling System was successfully used in conjunction with the prism tests to identify how geometry influences factors such as transfer length and splitting propensity. Lastly, a new ASTM measurement standard was proposed titled Standard Practice for Measuring Indented Steel Wire Geometrical Parameters, providing guidance on how the most important indent features are to be measured, using automated or manual methods, so that results can be repeatable from individual-to-individual or from lab-to-lab. The application of this research will help ensure that poor wire-concrete performance is identified prior to production.Item Open Access Simulation and utilization of irradiation facilities(2025) Crouch, BradleySimulations were created and utilized for different irradiation facilities to examine the effects that neutron and x-ray radiation has on Caco-2 and HepG2 cell cultures. Once outside Earth’s geomagnetic field, the radiation environment becomes more harsh, causing there to be greater risk to the astronauts. One of the major risks of interplanetary space travel is space radiation-induced carcinogenesis. With increased duration of the mission, the risk to the astronauts increases. This increased risk of carcinogenesis causes the maximum duration of a mission to be limited. The radiation field that impinges upon the astronauts is complex and is made up of a variety of radiation types. The complex field of space radiation needs a terrestrial experimental source for comparative studies. The radiation that was primarily examined in this work was neutron and x-rays. The neutron sources that were simulated are the KSU TRIGA Mark II Thermal Column and deuterium-tritium fusion neutrons. The x-ray sources were a 6 MV Varian LINAC and a RadSource RS1800 biological irradiator. Accurate understanding of the dose to astronauts is vital to astronaut safety and the success of the mission, which leads to the need for accurate models and simulation. The nuclear reactor model, which was partially modeled in a previous work, was upgraded to include the thermal column. An MCNP FMESH4 tally was used to determine the simulated neutron flux across the irradiation section of the thermal column. The output was converted to neutrons per kilowatt using the k_ef f and nubar. The neutron generator experiment room was modeled in previous work. The neutron generator had to be moved as the previous simulation had the source placed in a different location and the cell cultures were modeled. The cell culture dishes were modeled and located inside of the experiment room where they would be placed in a physical experiment. The MCNP F6 energy deposition tally was used to determine the dose rate from the neutron generators on the cells. The RS1800 was previously modeled, but the source term needed to be changed to account for the different voltage and current settings used for the experiments. The voltage and current control the x-ray spectrum; in the original model the settings were 130 kV and 1 mA for the voltage and current, respectively. For this work, the voltage was increased to 160 kV and either 1 mA or 12.5 mA were used for the current depending on if the irradiation was chronic or acute. An MCNP F4 tally was used with a energy-dependent response function to convert the flux density into dose rate. Experiments were conducted to examine the effects induced in the cells by different types of radiation. The doses to the cells that were irradiated were accurately characterized for x-ray and neutrons. The neutrons came from a deuterium-tritium fusion neutron generator with energies of 14.1 MeV and a dose rate of approximately 60 mGy h−1. The x-rays came from a RS1800 biological irradiator and a 6 MV LINAC; the dose rates of these machines varied and are discussed in the section with each experiment. In the neutron experiments, the dose rate was originally incorrectly found to be 5 mGy h−1. The target dose in the neutron experiments was 40-80 mGy, which would have taken 48-106 min rather than the 8-16 hours used in the experiment. The increased dose to the cells led to high cell death and very little usable data after the experiment. The x-ray doses ranged from 0.5 Gy up to 16 Gy in some experiments. Multiple cell assays were used in the quantification of the radiation damage including cell viability, reactive oxygen species (ROS), and double-strand break (DSB). Cell viability assays examine the survivability of cells post exposure. ROS assays examine the reactive oxygen species created by the cell in response to the radiation. The DSB assay stain the double-strand breaks caused by damage to the DNA making them quantifiable. The assays all utilize immunostaining to generate the fluorescence that is seen in the confocal images. These images were analyzed to get the data. After irradiation of the cells and the different cell assays were performed, there was a dose dependent response in the cell death using a live/dead assay. There was no change seen in the cell viability using a MTT assay because of the cell density. There was little to no ROS generated in any of the experiments, since Caco-2 and HepG2 are epithelial cell lines. There was a dose dependent response to the DSB generated after x-ray exposure to acute exposure. There were significantly fewer DSB generated after chronic exposure to x-rays, as expected, due to the smaller dose received at one time. In between fractions, the 24 hours of repair time allows for the cell to repair some of the DSBs.Item Open Access Digital twin incubator using ROS2 and model-driven development(2025) Thompson, BenjaminCyber-physical systems, computer systems that can interact with their environment us- ing actuators and sensors, can be very difficult to develop and ensure proper functionality, especially within a safety critical context. Digital twins are an increasingly popular tech- nique to help ensure the correct operation of these systems. Digital twin systems contain two parts: the physical twin, which is the cyber-physical system itself, and a digital twin, which is a digital representation of the physical twin that is used to perform runtime analy- sis, simulations of the physical twin using real-time sensor data, and perform self-adaptation on the physical twin to mitigate predicted faults. A digital twin system can be a very com- plex system with several components each needing to communicate with each other over a network in real time. Setting up these communication pathways by-hand can be very time consuming and potentially error-prone. This report examines how the Sireum High Assurance Modeling and Rapid engineering for embedded systems (HAMR) code generation tool and the Robot Operating System 2 (ROS2) may be used to improve the engineering of twinned systems. The investigation is based on a case study of a twinned system for an incubator for fermented soy-based food. The incubator system was originally designed by Feng et al (2021) at Aarhus University as an open source test bed for digital twin concepts. In addition to a cyber-physical system for controlling the environment in an enclosure for fermenting a soy-based food product, this incubator contains a digital twin service to predict if the incubator lid is open using a simulation and real-time sensor data, and can recalibrate the physical twin in response. Given a model of the twinned system written in the Architec- ture Analysis and Design Language (AADL), the experimental HAMR code generator for ROS2 can output a ROS2 package with ROS nodes for each system component, and all com- munication pathways completely configured. Utilizing the HAMR code generator for ROS2, an implementation was made that maintains temperature when the lid is closed, and detects & adapts to a lid open event and with fewer lines of hand-written code than the original Aarhus University implementation. This report finds that the use of these tools for digital twin development is promising, but more investigation is needed and some improvements to tooling need to be made.Item Open Access Job satisfaction of adjunct community college faculty in the Midwest post-COVID-19(2025) Kasuboski, Stephanie SanbeCOVID-19 was officially declared a pandemic by the World Health Organization on March 11, 2020, and it quickly affected everyone’s life as new protocols were established in all areas. The effects of the pandemic were long lasting, and many areas have not yet fully recovered. Community colleges were not immune to the challenges faced during the pandemic, and they continue to face them in a postpandemic environment. Course offerings, student enrollment, and course modalities changed seemingly overnight. Changes to students’ expectations and needs forced academic institutions to reexamine many aspects of their operations to meet the new normal created by the pandemic. To meet budgetary constraints, there has been a greater reliance on adjunct faculty at community colleges. Looking at job satisfaction and the factors that affect job satisfaction is vital to ensure there is a robust pool of qualified adjunct faculty to meet the needs of community colleges. This study was a quantitative research study with descriptive, comparative, and correlation and regression analyses. Using Maslow’s hierarchy of needs as the theoretical framework and Herzberg’s two-factor theory of motivation and hygiene as the conceptual framework, adjunct faculty teaching at nine community colleges, accredited by the Higher Learning Commission, in the Midwest, during the Spring 2024 semester were surveyed to determine their levels of job satisfaction and the factors that affect job satisfaction. The results were compared to the trends of job satisfaction found in a previous 2010 study. The results of this study show that 72.4% of adjunct faculty are satisfied with their jobs. They are most satisfied with the autonomy and independence and freedom to design course content that is afforded by their job. In addition, adjunct faculty are most satisfied with the competency of their colleagues and departmental leadership. Adjunct faculty are least satisfied with their prospects for career advancement, institutional support of travel for professional development, and benefits. There has been a slight decrease in the overall satisfaction of adjunct faculty from 2010 (M = 3.0) to 2024 (M = 2.9). However, the factors affecting job satisfaction have remained consistent across the two studies. The results of this study offer a comprehensive view of adjunct faculty, and an insight into what can be done to improve the teaching experience of adjunct faculty.Item Open Access Assessing impact of better foreign market accessibility on crop production and farm economy(2025) Kim, JiyeonThe interplay between international trade and agricultural policy is crucial to understanding current agricultural issues surrounding global agricultural markets. Understanding these dynamics is essential for addressing the challenges and opportunities the agricultural sector faces, which has been increasingly interconnected with international markets. U.S. agriculture has been experiencing increases in imports and exports of agricultural commodities over the last three decades with its trade liberalization. In particular, North American Free Trade Agreement (NAFTA) boosted agricultural trade among the United States, Canada, and Mexico by reducing trade barriers within those three countries. With better accessibility to foreign markets, U.S. agriculture may gain or lose from trade, and the impact of trade can be heterogeneous across regional or individual agricultural backgrounds. The potential benefits are particularly pronounced for exporters who experience significant reductions in tariffs on products that they produce as a result of trade liberalization. On the other hand, if individual farm operators lose their competitiveness in producing and exporting, it would impact farm business decisions on input use, crop choice, or exit from the market at worst. Hence, it becomes important to understand the impact of trade exposure on agricultural production and farm economy with a keen focus on identifying the heterogeneous effects across regions or individuals. The first study examines how U.S. crop acreage and yield respond to better foreign market accessibility caused by NAFTA focusing on the heterogeneous effects across regions with different export competitiveness and agricultural backgrounds. Focusing on the major field crops, corn, soybeans, and wheat, we compute the localized trade exposure and examine the effect of localized trade exposure on U.S. crop acreage and yield. Using a comprehensive dataset on crop production and bilateral trade data from 1991 to 2022, and localized trade exposure, we find that trade shocks from NAFTA have negative impacts on crop acreages but positive impacts on crop yield for corn and soybeans. In addition, the effects are heterogeneous by crops and different stages of NAFTA implementations. The second study estimates how the farm-level trade exposures from NAFTA affect the profitability of farms and, as a result, how changes in the profitability after the implementation of NAFTA impact the survival of farms. We estimate the effects of trade exposure on farm profit using a farm-level panel data and trade data from 1991 to 2022. We also employ a duration model to investigate the effects of trade exposure on farm exit. The findings of this study are mixed depending on how trade exposure is measured. When trade exposure is quantified by the U.S. revealed comparative advantage (RCA) in exports, trade exposure is positively associated with farm profitability and the likelihood of farm survival. However, when trade exposure is measured by the U.S. market share in NAFTA countries, the results suggest a positive impact of trade exposure on profitability, but a negative association between trade exposure and farm survival. The third study investigates effects of a free trade agreement from an importing country's perspective. Using farm-level panel data and bilateral trade data from 2003 to 2007, we directly estimate the impacts of the Korea-Chile Free Trade Agreements (FTA) on the revenue of farms in South Korea that faced greater imports – agricultural producers as the FTA induced greater imports of fruits and vegetables from Chile to South Korea. As expected, we find the negative effect of the increased imports on the total crop revenue and profit of the farms. We model and examine the differential impacts and find that the negative effects are greater for high-revenue farms. We document the evidence on the lack of immediate adjustment as a response to the negative shocks from the trade agreement.Item Open Access Using distribution and movement of invasive channel catfish Ictalurus punctatus in the San Juan River to inform removal efforts(2025) Epping, KeeganThe invasion of nonnative fishes has homogenized regionally endemic communities with species in the American West being disproportional impacted. In the San Juan River, New Mexico, Colorado, and Utah, invasive channel catfish Ictalurus punctatus may harm the native fish community through predation and competition. Because of this perceived threat, a removal program was implemented in the 1990s; however, exploitation rates have suggested that these efforts were insufficient to cause population declines necessitating reexamination of this management action. Quantifying aggregations and movements of channel catfish might allow managers to optimize the timing and location of removal efforts. We used active and passive radio telemetry to assess seasonal patterns in the distribution, aggregation, and movement of adults, and used temperature and activity sensors in some transmitters to identify behavior associated with channel catfish spawning which we corroborated through the back calculation of young-of-year otoliths to estimate hatch dates. We implanted 100 channel catfish in 2023 and 96 in 2024 with either a coded radio transmitter or a coded archive radio transmitter equipped with daily activity and temperature sensors. Tracking efforts occurred monthly outside of the spawning season and weekly during the expected spawning season (June-July) with raft-based tracking surveys. Despite a transmitter loss rate of 59% (n=116/196), we observed limited movement (< 5 river kilometers [rkm]) in spring/early summer followed by upstream movement in July in 2023 and May in 2024. Upstream movement coincided with warming water temperatures and largely occurred when the daily average water temperature reached 21°C, which is reported to initiate spawning for this species. Net movement was lower for fish < 440 mm TL (4.2 rkm) than for fish > 440 mm TL (14.4 rkm, p < 0.05). Linear mixed effects model results confirmed a positive relationship between movement rate and total length and a modal relationship between movement rate and a quadratic term for temperature with a predicted maximum movement rate identified at 22.1°C. Additionally, movement rate was 30.0% lower in 2024 compared to 2023 suggesting annual variability in movement patterns. Regression of activity as a function of temperature indicated that ten of twelve individuals displayed a modal activity pattern with predicted activity peaking in late-spring/early-summer at an average of 21.3°C. While our results do not suggest channel catfish have a propensity to aggregate, synchronized upstream movement likely cued by water temperatures near 21°C may provide the opportunity for resource managers to use passive sampling techniques to remove channel catfish during upstream spawning movements.Item Open Access Einstein constraints gluing and toroidal cusps(2025) Lasnier, ThomasIsenberg, Mazzeo, and Pollack construct a connected sum gluing for constant mean curvature initial data sets to the vacuum Einstein Field Equations, obtaining new initial data on the joined manifold. The new data set is arbitrarily close to the original data set outside of the gluing region, controlled by the length of the neck joining the manifolds. This approach is here summarized and then partially adapted in an attempt to create a gluing along toroidal cusps. The relevant differences and obstacles for this new gluing are discussed, restricting to the case of compact 3-manifolds and with a focus on the conformal vector Laplacian on toroidal cusps.Item Open Access Habitat use and diet overlap of Blue Catfish and Channel Catfish populations in two northeastern Kansas reservoirs(2024) Jackson, KadeBlue Catfish Ictalurus furcatus have increasingly gained recognition as a recreationally valuable species resulting in widespread stocking throughout the midwestern and eastern United States. Successful establishment and proliferation of stocked populations prompts questions about their impacts on other species of management interest through competition and predation. Standardized surveys in Kansas reservoirs have revealed increasing abundance of Blue Catfish populations following stocking. We hypothesize that increasing abundance of Blue Catfish might increase competitive interactions with Channel Catfish Ictalurus punctatus because they possess similar morphologies, life histories, and feeding strategies. Acoustic telemetry and gastric lavage were used to quantify the spatial and temporal habitat and diet overlap of these species in two northeastern Kansas reservoirs in 2023 and 2024. Generalized linear models and multivariate ordination techniques revealed that each species had differing spatial distribution patterns (p <0.001) and, on average, Blue Catfish occurred in deeper water (6.84 m) than Channel Catfish (5.09 m; p=0.048). We detected similar movement patterns for both species based on detections on receivers upstream of the reservoirs. Stomach contents of both species were comprised of diverse prey, but Channel Catfish fed more frequently on crayfish (p =0.001) and terrestrial macroinvertebrates (p = 0.022). Season had a strong effect on stomach contents (p = 0.001) for both species because of the occurrence of spring hatches of Giant Burrowing Mayflies Hexagenia limbata and fish eggs produced by spawning Longnose Gar Lepisosteus osseus, followed by a shift to terrestrial macroinvertebrates (p = 0.001) in the fall. Both species exhibit the potential to use a broad range of habitat and dietary resources; however, under high abundances of Blue Catfish, our data suggests that Channel Catfish might shift resource use to minimize interspecific interactions. Monitoring is necessary to evaluate populations trends and inform harvest management to prevent Blue Catfish populations from negatively impacting their own population and abundance and other species.Item Open Access Single molecule spectroscopic studies of solute nanoconfinement in nanoporous membranes and on surfaces(2025) Rashidi, HamidThis dissertation investigates the mass transport of molecules confined within anodic aluminum oxide (AAO) membranes and on PET microplastic surfaces, using fluorescence correlation spectroscopy (FCS) as a single-molecule detection technique. Rhodamine B (RhB) was employed as a fluorescent probe to study molecular dynamics and surface interactions. The first study focuses on understanding how solvent mixtures and solutes behave under nanoconfinement. To this end, RhB diffusion within 10 nm and 20 nm diameter AAO nanopores filled with ethanol/water mixtures was examined, with solvent compositions ranging from pure ethanol to pure water. The results revealed two distinct diffusion mechanisms, with mean diffusion coefficients, Df (fast) and Ds (slow), differing by nearly two orders of magnitude. Both Df and Ds were found to increase with pore size and were significantly lower than the bulk diffusion coefficient (Db) of RhB in the free solution. The fast diffusion component, closely related to mixture viscosity, represents hindered bulk-like diffusion in the central pore regions and is influenced by hydrodynamic drag and electrostatic interactions with the nanopore surface. In contrast, slow diffusion likely involves the adsorption of RhB to the pore walls governed by an adsorption-mediated mechanism. Trends in the autocorrelation amplitude and Ds exhibited a strong dependence on solvent composition, mimicking RhB solubility behavior. Ds was smallest in pure ethanol and pure water and largest in intermediate mixtures, suggesting that RhB surface adsorption is strongest in the pure solvents and weakest where the dye is most soluble in intermediate mixtures. The second study applies confocal fluorescence correlation spectroscopy (FCS) to investigate organic molecules adsorbed from aqueous solutions onto the surfaces of both virgin and post-consumer synthetic microplastics. The investigation includes fresh and artificially aged polyethylene terephthalate (PET) plastics, with the aging process meticulously conducted in a UV-ozone chamber. Raman spectroscopy confirms the composition of the PET microplastics, while water contact angle measurements and surface roughness analyses reveal increased wettability and changes in surface texture with aging, consistent with surface oxidation. Rhodamine B (RhB) dye, used as a fluorescent probe in the FCS experiments, serves as an analog for organic pollutants commonly found on microplastics. FCS results demonstrate dye accumulation on the PET surfaces as the plastics age, with significantly slower dye motion on the surfaces compared to the bulk aqueous solution. The dye undergoes anomalous subdiffusion on the PET surfaces, with diffusion rates slowing dramatically and becoming more anomalous as the plastics age. The reduced mobility is likely due to ionic interactions or hydrogen bonding between the dye molecules and the oxidized plastic surfaces. These findings offer critical new insights into how microplastics accumulate and transport organic pollutants as they undergo environmental weathering, contributing to our understanding of the risks associated with microplastic pollution.Item Open Access Paradigm-shifting back to the future: Evolutionary vs revolutionary shifts in cybersecurity best practices for U.S. colleges(2025) Lilly, JimThis qualitative multi-case study examines the impact of cybersecurity insurance, third-party providers, and endpoint protection on U.S. colleges' cybersecurity policies while highlighting the importance of internal IT skill growth and community involvement as a frontline defense. The Qualitative Case Study Research Design and the National Institute of Standards and Technology (NIST) CSF 2.0 are used as frameworks to explore U.S. colleges' cybersecurity risk management policies and practices. This study emphasizes fostering internal IT expertise, preventing IT staff deskilling, and enhancing the effectiveness of cybersecurity measures. The insights gained will inform best practices, policy development, and risk management strategies for cybersecurity in higher education. The findings indicate that leveraging the latest cybersecurity solutions, such as NIST CSF 2.0 and HEISC, is crucial for establishing a robust defense strategy. However, an over-reliance on third-party cyber vendors and cybersecurity insurance may be counterproductive due to minimal return on investment and substantial premiums. Instead, institutions should prioritize direct investments in cybersecurity measures, such as ongoing staff training and IT skill development, as evidenced by successful programs incorporating regular hands-on training sessions at larger institutions. Continuous risk assessments, adaptive best practices, and a focus on internal IT growth were identified as effective strategies, particularly for colleges that regularly updated their policies in alignment with NIST and HEISC frameworks. The study also emphasizes the deskilling IT personnel, which can occur when institutions overly depend on third-party providers or insurance. Participants engaging with state and federal cybersecurity programs was shown to be valuable for enhancing security beyond relying on insurance. These findings underscore the importance of proactive internal measures to strengthen resilience.Item Open Access Synchrony between fish feeding guilds and habitat associations in a regulated Great Plains river(2025) Rowley, LoganThe effects of river regulation on fish populations and their habitats are complex and further comprehension is needed for effective management and conservation. Specifically, we sought to understand if habitat variability alters the distribution of fish species and their diets in a Great Plains riverscape. Fish, aquatic macroinvertebrates, and habitat measurements were collected at seven sites in the regulated Kansas and Big Blue rivers. We used multivariate analysis of fish diets and fish habitat associations to identify feeding and habitat guilds and tested their dependencies using a fourth corner approach. We found that although there was a large degree of diet overlap for most assemblage members, species diets could generally be used to distinguish four feeding guilds: herbivore, omnivore, benthic invertivore, and pelagic/terrestrial invertivore. We also ascertained that species were distributed along a habitat gradient with mid-channel species like emerald shiners Notropis athernoides and carmine shiners N. percobromus on one end and a near shore assemblage of western mosquitofish Gambusia affinis, bluntnose minnows Pimephales notatus, and sand shiners N. stramineus on the other. The fourth corner analysis provided some support (p-value = 0.08) for the synchrony between the diets of species and their habitats, suggesting a mechanism by which river regulation and associated changes in habitat might influence fish populations through the food web. A more comprehensive understanding of how flow regulation impacts the distribution of habitats in the riverscape is necessary to better implement this knowledge into management and conservation of regulated rivers.Item Open Access The anatomy of hügelkultur and dissecting the key claims(2025) Hazan, SaraHügelkultur, German for “hill culture”, was first defined in 1962 and adopted by the permaculture community in the subsequent decades. The technique typically involves layering woody organic matter with soil and compost, or other available organic matter, to create a raised bed—which is then planted on all sides. Practitioners claim that the principles upon which hügelkultur function is grounded in science. However, no controlled, replicated research on inherent hügel bed characteristics or performance has been identified in the literature. This review seeks to ground the more prominent claims about hügelkultur by reviewing similar topics in published scientific literature. Hügelkultur proponents claim that, among other things, hügel beds reduce irrigation and fertility requirements, increase soil organic matter content, sequester carbon, and provide a beneficial microclimate for crop production. However, others point out that irrigation and rainfall may lead to runoff and erosion from the relatively steep slopes of the hügel beds; and, as the woody organic skeleton underlying hügelkultur breaks down, settling may harm established plant roots. While some of these claims may have merit based on the current understanding of plant and soil ecology, remain unvalidated in the specific context of hügelkultur. Where commercial applications could apply—e.g. distinct microclimates may have implications for season extension in annual specialty crops—further research is warranted. This review examines common claims found in anecdotal accounts and grey literature against relevant peer-reviewed literature, from related disciplines, to assess their potential validity and propose possible avenues for hügelkultur research.
