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Chronic Pain after Traumatic Brain Injury: Treatment Experiences and Effects on Cognition and Functioning
No full textTraumatic brain injury (TBI) can contribute to changes in cognitive and emotional functioning, quality of life, and psychosocial reintegration. Chronic pain is a common consequence of TBI which can uniquely impact such outcomes. Still, the exact nature of the contribution of pain on post-TBI outcomes remains unclear, and there are few existing studies exploring the treatment journey for chronic pain and injury rehabilitation through qualitative methods, specifically individual interviews with TBI survivors. This study aimed to document these narratives and to identify precisely how the experiences of TBI survivors seeking treatments, rather than the treatments themselves, impact outcomes. It also aimed to further elucidate the relationship between pain symptomology and TBI outcomes.
Ten adult TBI survivors with injuries ranging in severity from mild to severe engaged in a semi-structured interview about their recovery journey and their perspective on how their experiences have impacted them over time. Participants then completed a comprehensive neuropsychological assessment battery followed by self-report questionnaires and structured interviews about their mood, quality of life, psychosocial reintegration, and pain symptomology. Throughout the interviews, participants discussed the experience of being deemed ‘good enough’ and the many costs of TBI, as well as independence (both forced independence and functional independence) throughout their recovery. Overall, treatment experiences did not predict cognition. Some negative experiences were associated with more symptoms of depression and anxiety; however, negative experiences also predicted higher quality of life as it pertains to psychosocial reintegration and social support. Additionally, findings indicate that there may be a relationship between pain pattern and some aspects of cognition. Pain severity and pattern predicted more pain anxiety symptoms.
Despite noted limitations, this project provides unique insight into the lived experience of TBI survivors living with chronic pain and their views on the long-term impacts of their treatment experiences. This is important information for providers to have in order to better serve the TBI community. Additionally, this project demonstrates the important contribution of pain in TBI recovery. Further research is needed to better understand how cognition is impacted by treatment experiences and the unique contribution of pain on cognition and functioning after TBI.
Advisor: Kathy Chio
Two Essays on Index-based Risk Management in U.S. Rangeland and Livestock Production
No full textThis dissertation investigates two distinct but complementary dimensions of risk management in United States rangeland agriculture. Essay 1 measures spatial variation in basis risk within the Pasture, Rangeland, and Forage (PRF) rainfall-index program for 176 Nebraska grid cells (1988–2023). By linking official NOAA rainfall indices with 30-m Rangeland Analysis Platform biomass estimates, we find rainfall–forage correlations that peak at 0.45 but display pronounced heterogeneity. The probability that neither insured interval triggers during an actual forage loss averages 12%, rising to nearly 30% in several Sandhills cells, whereas optimally pairing late-spring and summer intervals reduces complete misses below 10%. These results underscore sharp grid-level disparities in PRF effectiveness and highlight the potential of interval tailoring to mitigate uncompensated drought losses. Essay 2 examines whether federally subsidized livestock insurance programs enhance production performance. Using a stochastic-frontier model with a control-function correction for the endogeneity of insurance, we analyze a county-level panel of 2,131 counties (2007–2022). An increase in the subsidy-to-liability ratio is associated with a reduction in mean technical inefficiency, with no statistically detectable effect on its dispersion. This finding indicates that, on average, larger subsidies strengthen managerial efficiency. Together, the essays show that PRF basis risk varies sharply across Nebraska grids and that higher federal livestock-insurance subsidies modestly increase average technical efficiency without changing its variance; careful rainfall-interval selection can improve the reliability of rangeland risk management.
Advisor: Jay Parson
Evaluation of Performance Characteristics and Groundwater Contamination Risks Associated with On-farm Swine Carcass Disposal Via Composting and Shallow Burial with Carbon
No full textThis dissertation evaluates the performance of three on-farm swine carcass disposal methods: whole carcass composting (WCC), ground carcass composting (GCC), and shallow burial with carbon (SBC), focusing on biosecurity factors and groundwater contamination risks. Foreign animal diseases (FADs), such as African swine fever and classical swine fever, pose severe economic and animal well-being risks if introduced to the United States. With confirmation of an FAD, swine movement will be halted, creating an urgent need for practical, biosecure, and environmentally responsible on-farm disposal strategies for swine carcasses. Nebraska, as a leading swine-producing state, exemplifies the vulnerability of high-density livestock regions to such disease outbreaks.
This project investigated performance of WCC, GCC, and SBC during a yearlong field study, transport characteristics through soils of leachate produced by each disposal method, and modeling of nitrogen transport from WCC and SBC methods using HYDRUS-1D to assess groundwater contamination risks. SBC emerged as a preferred disposal method, demonstrating achievement of time-temperature goals for pathogen destruction and significantly less leachate production compared to WCC and GCC. The model effectively captured vertical solute movement and decay kinetics, supporting the model’s utility for screening-level assessments, while also suggesting the need for enhanced reactive transport modeling in future applications.
Advisor: Amy Millmier Schmid
Hormonal Modulation of Sexual Approach and Avoidance Among Women with a History of Sexual Trauma
No full textA history of sexual trauma places women at a high risk for sexual dysfunction and other health sequelae, yet the influence of ovarian hormones in this population is poorly understood. This dissertation tested the theory that the effects of ovarian hormones are mediated by cognitive approach-avoidance systems to shape sexual well-being, and that this process is moderated by sexual trauma history. This was investigated across three studies examining the menstrual cycle, hormonal contraceptive use, and menopause. Across each chapter, I present complementary evidence demonstrating that hormones interact with the interpretation of ambiguous internal and external cues with respect to sexual approach and avoidance outcomes, and a putative role of physical health factors. This research advances an integrated biopsychosocial model, pointing to the need for trauma-informed clinical care that targets cognitive appraisal and the drivers of sexual avoidance to improve women\u27s sexual well-being across the lifespan.
Advisor: Tierney K. Loren
An Eye Tracking Study Assessing How Developers Read Stack Overflow to Summarize APIs
No full textStack Overflow is a question-and-answer forum for software developers. This resource provides essential information to developers working on a variety of tasks, helping improve productivity. Despite its popularity, there is limited understanding of how developers read, understand, and extract information from Stack Overflow pages. This thesis presents an eye-tracking study designed to investigate the behaviors of software developers as they summarize API elements using information from Stack Overflow. Through a controlled experimental design involving 30 eye-tracking sessions, the research examines the specific content elements developers prioritize and how closely their summaries reflect the information they read.
Results showed that developers predominantly focused on question texts and question code snippets. Semantic similarity analysis conducted using Sentence-BERT revealed a moderate alignment between the developers\u27 summaries and the content they read on Stack Overflow. These findings imply that Stack Overflow\u27s specific content structure can significantly support developer understanding and productivity. This highlights the potential for enhancing informal documentation and the design of future educational tools and resources for increasing developer efficiency
Controlled Fabrication of Continuous Nanofibers, Assemblies, and Nanocomposites
No full textContinuous nanofibers (NFs) represent a unique class of nanomaterials with numerous advantages for a large number of applications. The recent discovery of concurrently high strength, stiffness, and toughness in ultrafine electrospun nanofibers has sparked significant interest in controlling fiber diameter. A considerable research effort has been dedicated to analyzing the effects of process parameters on diameter. However, uniform fabrication of ultrafine continuous nanofibers remains elusive. The objectives of this thesis were to explore further and study several new methods of controlled fabrication of nanofibers, their assemblies, and nanocomposites. The possibility of fiber diameter control by varying environmental factors has been analyzed. Nanofibers have been electrospun at different temperatures and relative humidities (RH). Evaluation showed that, unexpectedly, high RH increased fiber diameter for organic solvent-based systems. The vapor-induced phase separation mechanism of this unusual phenomenon has been proposed and verified. It was shown for the first time that solvent vapor-assisted electrospinning can lead to uniform, smooth ultrafine NFs. Additionally, a method for the controlled fabrication of large, aligned 3D nanofiber assemblies has been developed and demonstrated using a modified split electrode approach. The method is suitable for the continuous production of large nanofiber constructs with tunable NF density. A non-destructive optical evaluation of NF density has also been demonstrated. Finally, the possibility of integrating NFs with Digital Light Processing (DLP) polymer additive manufacturing and controlling the “writing” of NFs on substrates has been explored. DLP-produced nanocomposites exhibited significantly improved mechanical toughness. The results of this thesis can be used for controlled nanomanufacturing of strong and tough NFs, their 3D assemblies, and composites for various structural and functional applications.
Advisor: Yuris Dzeni
Application of Cementitious Materials and Fiber Reinforcement to Enhance Lime Stabilization for Nebraska Shale Soils
No full textLime stabilization is a widely used technique to improve weak subgrades; however, its effectiveness under freeze-thaw cycles remains a critical challenge. This study investigates the incorporation of cementitious materials and fiber to enhance the mechanical properties and environmental resistance of lime-stabilized soils under such conditions. Two types of soil, gray shale (plasticity index of 37.8) and clay soil (plasticity index of 19.0) from Nebraska, were used. Stabilization mixtures included lime dosages of 0%, 3%, and 6% by weight, combined with either 10% fly ash or 3% and 6% cement by weight, and 0% and 1% fiber. The experimental program comprised a multi-tiered approach: characterization of physical properties through geotechnical tests (e.g., particle size distribution, Atterberg limits, and standard Proctor tests), preparation of composite specimens for unconfined compressive strength (UCS) and direct shear testing, and evaluation of environmental resistance through freeze-thaw cycles (7 cycles after 14 days of curing and 12 cycles after 28 days of curing). Additionally, large-scale testing was conducted using the Large-Scale Track Wheel test to simulate field conditions. Results showed that lime and fly ash significantly reduced the plasticity index of gray shale, with less pronounced effects on clay soil. The UCS values for gray shale ranged from 61.2 to 300.7 psi for lime stabilization, 137 to 272 psi for lime and fly ash stabilization, and 129 to 490.8 psi for lime-cement stabilization. For clay soil, UCS values ranged from 68 to 149 psi for lime stabilization, 119 to 146 psi for lime and fly ash stabilization, and 204 to 379.2 psi for lime-cement stabilization. The inclusion of fiber further enhanced the shear strength parameters of the soils, particularly increasing cohesion. Cement-lime stabilization demonstrated superior UCS retention and resistance to freeze-thaw cycles for both soil types, outperforming lime alone and lime-fly ash treatments. These findings highlight the importance of incorporating cementitious materials to enhance the durability and performance of lime-stabilized soils under harsh environmental conditions
Details Matter: Getting People Involved
No full textSometimes getting people into the habit of community participation can be a bit challenging, but two aspects can help make this a little easier. The first is to make sure that there are no organizational barriers in participating, and the second is to realize that community participation happens on several levels and that each level has certain expectations. When these expectations are clearly stated, people are more easily motivated to get involved and stay involved.
Setting up engagement from the beginning requires thought and attention to detail. It can be insignificant things, like choosing a date or picking a location, that impact participation. Also, knowing the level of participation desired or expected can either encourage or discourage future community participation. Details like these are easily overlooked. But, with a little careful planning, they become a personal and professional habit that builds up a positive culture of community participation
Native Americans, Part II
No full textThe Civil Rights Movement of the 1950s and 1960s – aimed at abolishing legalized racial segregation and discrimination across the United States – found expression in Nebraska in many ways. From college protests to marches in Lincoln, the movement found a home within the youth and counterculture communities of Lincoln and Omaha. But less known is the way the movement impacted Native American populations, especially those in remote Nebraska communities. “Just as young Hispanics, Asians, and Native Americans across the nation were learning the lessons of the black experience of the 1960s and expressing their identity as they sought to claim their own niche in society in the early 1970s, so too Mexican Americans and Indians were becoming more visible in Nebraska,” write authors James C. Olson and Ronald C. Naugle.1 The most visible push for Native American civil rights could be seen in the efforts of the American Indian Movement, an indigenous rights organization established in 1968 in Minneapolis. The organization emerged on the national scene following its occupation of Alcatraz Island in 1969 before taking over Mount Rushmore and the Mayflower II. In Nebraska, AIM garnered headlines while protesting the February 1972 death of Raymond Yellow Thunder, a 51-year-old Lakota man whose beaten body was found in a pickup truck in Gordon. But even before Yellow Thunder’s death, Native American people in Nebraska towns like Alliance and Scottsbluff fought for their civil rights following the deaths of Native people in jails and at the hands of non-Native perpetrators.
Native advocates succeeded in creating a state organization charged with monitoring Native issues and legislation and coordinating the efforts of state agencies as they responded to Native needs and concerns. The Nebraska Unicameral chartered the Nebraska Commission on Indian Affairs in 1971 under the leadership of Leonard Springer, vice-chair of the Omaha tribe and leader in the Native American Church. While many historians mark the first instance of American Indian activism in Nebraska as the 1972 AIM march in Gordon following Yellow Thunder’s death, still others point to the efforts of Native people in western Nebraska to call attention to the deaths of Native inmates as among the first examples of indigenous activism in the state. And still others argue the long road to civil rights for Natives in Nebraska began even earlier. Author David Christensen argues that the roots of civil rights for Native people in Nebraska developed in the early 20th century in western Nebraska’s potato fields
