Digital Commons Network^™

Post-Fire Soil Health Assessment Of The Grasslands And Woodlands In The Semi-Arid Nebraska Sandhills, Stephanie M. Lugo

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Grasslands in the Nebraska Sandhills are shaped by natural wildfires, which help maintain the structure and function of native grasslands. In recent decades, afforestation with ponderosa pine and eastern redcedar has introduced new woodlands that altered the region’s fire dynamics and raised important questions about the effects of wildfire on different vegetation types. As wildfires become more frequent, understanding their impacts on soil health in grasslands and woodlands becomes increasingly important. This study examines the short-term effects of the 2022 Bovee Fire on physical, chemical, and biological soil properties in native grasslands and ponderosa pine and eastern redcedar afforested woodlands. …

A Low-Power Mixed-Signal Potentiostat System-On-Chip With Integrated Dual-Slope Adc, Seth Mcrobert

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

This thesis presents the design and characterization of a low-power mixed-signal potentiostat that was integrated with a 65 nm core in a SoC for low-power electrochemical sensing applications. The system integrates a low-noise transimpedance-based potentiostat front end with a 12-bit dual-slope analog-to-digital converter (ADC) for accurate current-to-digital conversion. The potentiostat core—comprising the control amplifier, current-mirror network, and transimpedance amplifier—consumes 38.2 µA from a 2.5 V supply (95.5 µW) and achieves an input-referred noise floor of 113 µVRMS over a 330 Hz bandwidth, while having an input current range from 1 nA to 20 µA and a noise-limited sensitivity of 56.4 …

Llm-Assisted Cwe Identification, Severity Assessment, And Vulnerability Description Generation, Mohammad Jalili Torkamani

School of Computing: Dissertations, Theses, and Student Research

Identifying the underlying weakness types and assessing their severity using CWE and CVSS standards are critical steps in software vulnerability management. While timely assessment of vulnerabilities mitigates the impact of severe security incidents, automating joint CWE identification and severity assessment remains challenging due to the heterogeneity of vulnerabilities across different code granularities and programming languages. In addition, generating vulnerability descriptions is often time-consuming, as it requires extensive manual review, validation, and writing by security experts.

In this thesis, we leverage the capabilities of Large Language Models (LLMs) to automate the identification of CWE identifiers and the assessment of their severity …

Evaluating Metamitron Efficacy For Glyphosate-Resistant Palmer Amaranth (Amaranthus Palmeri) Management In Sugarbeet Across The Central High Plains, Abraham Akuoko

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Herbicide-resistant (HR) Palmer amaranth (Amaranthus palmeri S. Watson) is regarded as one of the most prominent weeds within sugarbeet fields across the Central High Plains, with limited chemical control options. Although a few herbicides are available, their use is restrictive due to crop injury concerns and can only be applied at or after the 2–4 true leaf (TL) growth stage, which will provide no control for already emerged weeds. However, Palmer amaranth often emerges between sugarbeet planting and the 2 TL sugarbeet growth stage. Consequently, as of 2023, there were no herbicide options to control Palmer amaranth in sugarbeet …

Fragmentation In The U. S. Fed Cattle Market: Implications For Price Transparency And Discovery, Taralee M. Hudson

Department of Agricultural Economics: Dissertations, Theses, and Student Research

The U.S. fed cattle market is one plagued by recurring stakeholder concern. Market participants frequently raise questions about the transparency of fundamental information under existing reporting frameworks, and the extent to which Private Negotiation, the dominant trading institution, effectively facilitates price discovery. Although extensive research has sought to address these issues, much of it has failed to account for the market’s increasingly fragmented structure. This thesis is comprised of three chapters that collectively examine price transparency and discovery through the lens of market fragmentation. Each chapter presents research related to the fed cattle market and is intended to stand …

Developing A Metabolic Engineering Chassis From A Metabolically Versatile Organism, Rhodopseudomonas Palustris Cga009, Mark William Kathol

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Metabolic engineering has made it possible to develop biological processes that were once considered economically unfeasible or uncompetitive. This field has enabled both a robust niche market, whereby products, such as pharmaceutical substances like monoclonal antibodies, are produced exclusively through biological means, as well as an emerging commodity production market. Nonetheless, significant challenges remain in harnessing the unique metabolic capabilities of genetically non-tractable organisms. This dissertation focuses on Rhodopseudomonas palustris CGA009 as a potential chassis for metabolic engineering. To address the issue of genetic intractability, a synthetic biology toolkit was developed to facilitate the expression of heterologous proteins in R …

Realism, Truth, And Commitment: An Exposition And Critique Of Michael Devitt's Constitutive Account Of Realism, Samuel Elias Hobbs

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Michael Devitt argues in Realism and Truth that positive semantic issues are not constitutive of realism concerning the mostly impersonal external world. This is motivated by his second maxim which prescribes that the metaphysical (ontological) issue of realism is to be (sharply) distinguished from any (positive) semantic issue. Devitt’s argument is that his view of realism, entitled ‘Realism’, doesn’t entail and isn’t entailed by any doctrine of truth.

This dissertation presents a critique of the argument indicated above and, thereby, Devitt’s second maxim. I present Devitt’s account of Realism and his overview of theories of truth. I next present Devitt’s …

Evaluation Of Distractor Model Specifications On Assessment Quality Within The Framework Of Assessment Engineering, Sunhyoung Lee

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Responding to the high demand for new test items, model-based item development has emerged as a promising approach for efficient item creation. Item models within Assessment Engineering (AE) offer a systematic framework that effectively generates a large volume of new items. In the development of multiple-choice questions, well-constructed distractors are essential for ensuring item quality, although creating them requires significant time and resources. A distractor model is a sub-model within an item model, producing correct answers and distractors aligned with all potential items to be generated. Various types of distractor models have different characteristics and offer efficient methods for generating …

Characterization Of Mitochondrial Dna Repair Components And Repair Choices At Targeted Double-Strand Breaks In Arabidopsis Thaliana, Moira Rodriguez

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Plant mitochondrial genomes are complex when compared to most other eukaryotic mitochondrial genomes. They are large and variable in size, expand and rearrange frequently, abundant in non-tandem repeats, but maintain a very low synonymous substitution rate in the remaining coding regions. Many of these complexities can be explained by the increased use of double-strand break repair for DNA damage. To advance the understanding of mitochondrial genome dynamics as it relates to double-strand break repair, we performed a forward genetics screen to identify proteins involved in DNA repair in plant mitochondrial genomes. Through this screen, we identified an RNA/DNA helicase, Suv3, …

Reinforcement Learning Based Security Schemes For Distributed Ai Systems, Ashan Chamath Gunawardena

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Distributed machine learning (DML) is a component of modern intelligent systems, enabling collaborative training across devices such as mobile clients, vehicles, and edge networks. However, the decentralized nature of these systems introduces vulnerabilities, particularly data poisoning attacks that compromise model integrity and degrade performance. Traditional defenses, such as statistical filtering, robust aggregation, and privacy-preserving techniques, often struggle to adapt to overwhelming adversaries or operate under strict privacy and real-time constraints. This dissertation proposes the use of reinforcement learning (RL) and deep reinforcement learning (DRL) based misbehavior detection schemes that dynamically identify poisoning attempts in distributed AI systems, including federated learning, …

Investigating Programming Behaviors To Understand Student Engagement And Experience In Introductory Programming Courses, Marcus Eugene Gubanyi

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Introductory programming courses are foundational to developing students’ problem-solving abilities and shaping their persistence in computing pathways. Engagement with programming tasks plays a central role in student learning and experience. Many research measures, including self-reports and code submissions, offer only a limited view of student engagement with programming tasks. This dissertation leverages programming process data, consisting of keystrokes and compilation events, to capture the programming process as it unfolds and to investigate observable programming behaviors. Guided by educational theories, three studies examine how students’ programming behaviors vary across instructional and assessment contexts, how they relate to motivational profiles, and how …

Proso Millet In Us High Plains Dryland Agriculture: Systems Resilience, Phenology, And Consumer Preferences For Alternative Grains, Pratiksha Baishya

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Dryland crop production in Nebraska's semi-arid High Plains faces challenges from fluctuating weather impacts of climate change, including extreme temperatures, short growing seasons, and recurring droughts. Proso millet is an alternative crop used to build a more robust three-year rotation in the region, rather than the traditional two-year wheat-fallow cycle. This dissertation provides a systems-level assessment of proso millet, a climate-resilient crop with great potential to support sustainable cropping systems in the US High Plains. Using a field-to-consumer approach, it highlights its agronomic and environmental advantages in dryland rotations, develops a phenological framework to aid future research on production, crop …

Making Deep Neural Networks Trustworthy: Intelligibility And Safety Through Symbolic Methods, Eleanor Catherine Quint

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The rapid adoption of deep learning has come at the cost of properties long valued in artificial intelligence: intelligibility and safety. This dissertation develops methods that restore these properties by coupling neural networks with symbolic structure.

First, for supervised classification, I propose a differentiable decision tree integrated with a supervised variational autoencoder. The resulting model maintains competitive accuracy and generative performance while exposing clear macro-features in its latent space, improving interpretability.

Second, for reinforcement learning, I extend constrained Markov decision processes by specifying constraints in formal languages. This formal language constrained MDP enables the use of automata for state augmentation, …

Modelling Groundwater Nitrate Transport In Bazile Creek Watershed Using Modflow, Prajwol Thapa

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Excessive application of inorganic nitrogen fertilizers has led to pervasive nitrate contamination of groundwater in agricultural regions worldwide. This study evaluates the fate and transport of nitrate beneath the Bazile Creek watershed in northeastern Nebraska by coupling groundwater‐flow (GWF) and solute‐transport (GWT) simulations within MODFLOW 6. A conceptual model was developed using hydrogeologic, topographic, recharge, and boundary‐condition data, and the domain was discretized with a quadtree-refined grid to capture surface-subsurface interactions. The steady-state flow model was calibrated against observed hydraulic heads and baseflow measurements using NSE, RMSE, and PBIAS metrics, and subsequently extended to a transient flow simulation spanning 2002-2023. …

Recovery And Characterization Of Moraxella Species From Bovine Specimens, Laura G. Leger

School of Veterinary and Biomedical Sciences: Dissertations, Theses, and Student Research

The family Moraxellaceae is made up of a diverse group of 24 named species that fall into three phylogenetic groups. While most Moraxella spp. act as commensal respiratory and/or ocular flora of mammals, some are associated with disease. One of these diseases, infectious bovine keratoconjunctivitis (IBK), has significant welfare and economic impacts to both cattle and cattle producers. Moraxella bovis is the only experimentally determined cause of IBK, however, an association of Moraxella bovoculi with disease has been proposed. Currently, available vaccines do not have high levels of efficacy in the field. Culture based methods are the gold standard for …

Amplifying Mother Leaders’ Voices: A Feminist Inquiry Into Gender Inequity In Higher Education Leadership, Katherine Bard

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Women now comprise more than half of mid- and upper-level administrators in higher education, yet they remain underrepresented in the most senior leadership roles. For mothers in leadership, this underrepresentation is compounded by gendered structures, expectations, and norms that shape their personal and professional lives in distinct ways. While scholarship has examined working motherhood broadly and gender inequity in higher education separately, little research has focused on how mother leaders experience and interpret gender inequity in higher education leadership. This study sought to address that gap by exploring the lived experiences of ten mother leaders working at research-intensive (R1) universities …

Ethical Decision-Making Processes In Authentic Environmental Engineering Contexts Through Systems Thinking And Team Collaboration Lenses: An Embedded Single Case Study, Toluwalase Eniola Brower

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Ethical and professional responsibility is a critical learning outcome emphasized in ABET accreditation. However, ethics instruction in engineering education often lacks integration of system-level considerations such as economic, environmental, and societal contexts, that are essential for developing engineering solutions that ensure the safety and welfare of diverse stakeholders. This embedded single-case study investigated the integration of authentic ethics instruction within a junior-level environmental engineering course at a Midwestern U.S. university during spring 2025 and explores how civil engineering student teams within the course engage in ethical decision-making process during authentic problem-solving.

The instructional intervention consisted of four problem-based ethics modules, …

Changepoint Detection As Model Selection: A General Framework, Michael A. Grantham

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation presents a general framework for changepoint detection based on ℓ₀ model selection. The core method, Iteratively Reweighted Fused Lasso (IRFL), improves upon the generalized lasso by adaptively reweighting penalties to enhance support recovery and minimize criteria such as the Bayesian Information Criterion (BIC). The approach allows for flexible modeling of seasonal patterns, linear and quadratic trends, and autoregressive dependence in the presence of changepoints.

Simulation studies demonstrate that IRFL achieves accurate changepoint detection across a wide range of challenging scenarios, including those involving nuisance factors such as trends, seasonal patterns, and serially correlated errors. The framework is …

In-Field Tractor Operational Load Profile Generation In Support Of Advanced Tractor Testing In Mixedmode Power, Andrew Donesky

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation addresses the need to better characterize real-world tractor power requirements across drawbar, power take-off (PTO), and hydraulic modes to support more representative tractor testing. Conventional testing protocols, such as OECD Code 2, emphasize steady-state performance under controlled high-load conditions, which do not reflect the mixed and dynamic demands of modern field operations. To address this gap, a Tractor Instrumentation System (TIS) was developed, validated, and deployed to collect high-resolution, mixed-mode power data during planting, anhydrous ammonia application, and grain cart operations. The TIS integrates physical sensors, including custom load pins, hydraulic pressure/flow sensors, and a redesigned PTO torque …

The Motivation And Influence Behind The Decisions Of High School Students To Participate In The National Ffa Organization, Taylor A. Nielsen

Department of Agricultural Leadership, Education, and Communication: Dissertations, Theses, and Student Research

Today, high school students are increasingly engaged in extracurricular activities, navigating a diverse range of options for which clubs and organizations to join during their secondary education. This poses a challenge for students and for Career and Technical Student Organizations as they work to recruit talented students. High school students have several influences and pressures on their time, including peers, family, and teachers. These influences often recognize how organizations such as FFA can be pivotal in shaping students’ personal and professional development. We wanted to explore the motivations and influences guiding high school students’ decisions to join and actively participate …

Rapid State-Of-Health Estimation Of Batteries Using Machine Learning With Limited Eearly-Discharge Voltage Data, Mohammad Bakhtiari

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

The utilization of lithium-ion batteries has been rapidly expanding across diverse sectors, including electric transportation, stationary energy storage systems, and the built environment. Ensuring a high level of reliability in these applications is essential, as the performance and safety of such systems depend strongly on the accurate assessment of the battery’s State of Health (SOH). Conventional SOH estimation techniques—often based on complex electrochemical models or extensive laboratory testing—tend to require a large number of measurements, advanced instrumentation, and high computational cost. These factors make them impractical for large-scale deployment or real-time monitoring. This study introduces a simplified machine-learning-based approach for …

The Graphic Shift: Leveraging Superhero Graphica To Un-Ban Critical Conversations In The Secondary English Language Arts Classroom, Avery Clason

Department of English: Dissertations, Theses, and Student Research

This thesis investigates the challenges that books are receiving during an era of social and political turmoil based on their content. Understanding why these books are polarizing for most readers and the general public is in direct connection with finding different books that can harbor the same conversations about dense topics and cultivating connections between students, the text, the world, and themselves. While there has been a search to find alternate books that are not considered "political flashpoints,” there has been limited research into the use of superhero graphica in the ELA classroom, especially in connection to utilizing this genre …

Early Childhood Educators' Perception Of Burnout: Impact On Educator Self-Efficacy, Teacher-Child Relationships, And Children's Emotional Regulation, Isaac M.D. Bowman

College of Education and Human Sciences: Dissertations, Theses, and Student Research

Early childhood educators (ECE) play a critical role in the academic advancement and nurturing care provided to children in their care, a distinct difference in role and responsibilities compared to traditional K-12 schooling. Published by the Buffett Early Childhood Institute, a report pertaining to ECE turnover revealed a nearly 40% annual turnover rate. Factors ECEs previously attributed to their exit of the early childhood education field involve low wage, low self-efficacy, and dealing with challenging behaviors. While not an exhaustive list, in a field relying predominantly on routine and consistency, ECE turnover rate highlights a necessity in exploring potential indirect …

Ethnic Identity, Parental Involvement, And Academic Outcomes: A Qualitative Study Of African International Students' Experiences, Kenanile Olivia Marie-France Bigba

College of Education and Human Sciences: Dissertations, Theses, and Student Research

This qualitative study explored how parental involvement intersected with cultural backgrounds and values through ethnic identity formation among African international students, and how these interactions influenced students' self-concept clarity, self-esteem, and subsequent academic attitudes and performance. Using hermeneutic phenomenological methodology guided by van Manen’s (2023) approach, the study conducted in-depth, semi-structured interviews with African international students (one from East Africa, one from West Africa) enrolled at a Midwest university. Through systematic thematic analysis, five interconnected themes emerged: (1) Evolving Parental Involvement, from direct guidance to distant trust, revealing how parental engagement transforms across geographical distance with financial circumstances moderating this …

Assessing The Language And Reading Abilities Of Students With Mosaic Down Syndrome, Emma G. Conradi

College of Education and Human Sciences: Dissertations, Theses, and Student Research

Language and reading are important skills for academic and social success, yet individuals with Down syndrome often face significant challenges developing these skills (Abbeduto et al., 2007; Martin et al., 2009). However, almost all the available research on the language and reading abilities of individuals with Down syndrome comes from research focused on individuals with Full Trisomy 21. To date, there has been virtually no research specifically examining the language and reading skills of individuals with mosaic Down syndrome (Buckley & Bird, 2002), a rare karyotype of Down syndrome. Therefore, the purpose of this study is to describe the language …

How Presidents Shift Ideological Stances In Legislative Elections: Evidence From South Korean Presidential Speeches, Doyeon Park

Department of Political Science: Dissertations, Theses, and Student Research

Presidents have a strong desire to lead their parties to victory in elections. However, relatively little attention has been paid to their ideological stances in legislative elections. This contrasts with extensive research on the ideological strategies of parties and candidates who directly compete for office. How do presidents adjust their ideological positions in legislative elections? This study examines the institutional dynamics surrounding presidents, focusing on their dual responsibilities and the role of legislative elections as a referendum on the presidency. It also considers presidential popularity as a factor that influences these dynamics. I argue that presidents are more likely to …

Defining The Causal Contribution Of The Gut Microbiota To Cardiomyopathy Pathogenesis As A Basis For Developing Microbiome-Targeted Therapies, Xu Shi

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Heart failure (HF) is a leading cause of morbidity and mortality worldwide, placing substantial clinical and economic burdens on society. Although advances in therapy have improved patient outcomes, the biological mechanisms that drive HF onset and progression remain incompletely understood. Increasing evidence suggests that the gut microbiota, the trillions of microorganisms residing in the gastrointestinal tract, plays a key role in some forms of heart disease, especially cardiovascular disease. Moreover, gut microbial dysbiosis has been associated with systemic inflammation, metabolic imbalance, and immune dysregulation, all of which contribute to the pathophysiology of HF. Cardiomyopathy, a primary disorder of the heart …

The Partsongs Of Samuel Coleridge-Taylor, Alan Davis

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This document examines the complete set of thirteen partsongs by Samuel Coleridge-Taylor (1875-1912) a body of choral works underrepresented in both scholarship and performance. Before the twentieth century, English partsongs had already developed a rich lineage through composers such as Charles Hubert Hastings Parry, Charles Villiers Stanford, Edward Elgar, and Charles Wood. Around 1900, the genre flourished further in the works of Gustav Holst, Ralph Vaughan Williams, Gerald Finzi, and Herbert Howells, whose partsongs were published by Novello & Co. and featured in The Musical Times. Within this broader context, Coleridge-Taylor’s contributions stand apart: his partsongs reveal a distinctive harmonic …

Soil Characterization With Proximal Geophysics, Sophia M. Becker

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

High quality soil data is crucial for addressing numerous threats to human well-being such as water scarcity, food insecurity, and intensified natural disasters. True soil property values are determined by analyzing soil samples in a laboratory, but soil sampling is often expensive and time-consuming. Some in-field point sensors and remote sensing products are available to measure soil properties, but they have inherent limitations in measurement extent and resolution. Geophysical methods can fill the measurement scale gap between point measurements and remote sensing products, but various research questions remain open. This dissertation aims to advance understanding of geophysics-derived soil property measurements …

An Integrated Modeling Framework To Evaluate Circularity Of The Corn–Water–Ethanol–Beef Nexus, Heydi Han

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation examines the transition from conventional linear agricultural and food bioenergy systems toward more circular, resilient, and resource-efficient configurations. Prior research indicates that spatial and temporal variability in soil, weather, animal biological responses, and management decisions strongly influences productivity, nutrient-use efficiency, and profitability. Studies have also shown that a diversified circular system can buffer these sources of variability, improving stability and adaptive capacity. Building on these insights, the central focus of this work is to develop an integrated modeling framework to evaluate circularity within the Corn-Water-Ethanol-Beef (CWEB) nexus and explore how climate variability and management choices shape system-wide performance. …