Two Essays On Index-Based Risk Management In U.S. Rangeland And Livestock Production, Wajdi Belgacem

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

This 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 …

Assessing The Impact Of Pll And Ple Concentrations And Aging On Protein Condensates Formation Via Llps, Nabil Harche

Theses, Dissertations and Culminating Projects

Protein droplets, also referred to as condensates, are membrane-less organelles formed through a biophysical process known as liquid-liquid phase separation (LLPS). These structures play an indispensable role in a wide range of cellular functions, including compartmentalizing biochemical reactions, regulating gene expression, and responding to cellular stress. Unlike traditional membrane-bound organelles, these condensates form dynamically and reversibly within the cytoplasm or nucleus, without the need for lipid membranes. The formation of these protein droplets is affected by several physicochemical factors, including pH, temperature, ionic strength, concentration of biomolecules, and specific molecular interactions such as electrostatics and hydrophobic forces. LLPS results in …

Crustose Coralline Algae Accretion In A Kelp Forest Ecosystem In Southern New England, Usa, Ruimeng Liu

Theses, Dissertations and Culminating Projects

Temperate reef ecosystems are experiencing rapid canopy loss of kelp and the proliferation of algal turf. However, the consequences of these changes for crustose coralline algae (CCA)— a key but often overlooked benthic calcifier—are poorly understood. Here, I study CCA recruitment patterns in southern New England, USA, using standardized settlement tiles at two field sites over 12 months (September 2023 – August 2024). I measure CCA accretion rates and the associated biological and environmental correlates of CCA recruitment. At the two sites, CCA accretion rates ranged from 0.0259 to 1.215 mg CaCO3 cm⁻² yr⁻¹, with an average of 0.441 mg …

Electrophysiological Markers Of Emotion Dysregulation In Autistic Youth, Rachel G. Mcdonald

Theses, Dissertations and Culminating Projects

Emotion dysregulation (ED) is a transdiagnostic mechanism that is conceptualized as difficultly regulating emotions and deploying appropriate regulation strategies in response to environmental stimuli. Meta-analyses suggest that autistic people, across the lifespan, experience more severe ED as compared to both neurotypical people and those with mental health conditions. Despite elevated risk and evidence linking ED to disruptions in neural mechanisms, no studies to date have examined neural markers of ED in autistic populations. The current project uses multi-method and multi-informant measurement to examine similarities and differences in neural mechanisms of ED in autistic and non-autistic populations. Forty-four youth aged 11—17 …

Comparative Expression Of Cgmp-Dependent Protein Kinase G (Pkg) From Plasmodium And Toxoplasma, Tsopmo Asaah

Theses, Dissertations and Culminating Projects

Malaria and Toxoplasmosis are life threatening diseases to humans. The search for a cure and control of these diseases is still one of the major challenges of scientists worldwide. In this research we focused on two Malaria species; Plasmodium bergei² (Pb) and Plasmodium falciparum¹ (Pf) and also on Toxoplasma gondii. Part of the life cycle of these organisms is regulated by the enzyme cyclic GMP-dependent protein kinase G (PKG)⁴. This is our drug target in this research. We believe that inhibiting this enzyme will be a great step in fighting these diseases. In this research, we devised a comparative study …

Regulation Of Icer Degradation And Its Role In Melanoma, Justin Wheelan

Theses, Dissertations and Culminating Projects

Melanoma is the deadliest form of skin cancer, with 100,640 new cases and 8,290 deaths estimated in the United States in 2024. While targeted therapies and immunotherapy have improved patient outcomes, resistance remains a major challenge, necessitating new therapeutic approaches. Approximately 50% of melanomas harbor BRAFⱽ⁶⁰⁰ᴱ mutations, leading to constitutive MAPK pathway activation. Targeted small molecule therapies such as BRAF and MEK inhibitors are available and initially reduce tumor burden, however resistance frequently occurs, likely through many pathways including compensatory activation of cAMP signaling. ICER (Inducible cAMP Early Repressor), a transcriptional repressor of CREB-mediated gene expression, is absent in melanoma …

A Pilot Study Exploring Vitamin D, Mental Health, And Gastrointestinal Health In Humans, Brianna C. Williams

Master's Theses

Mental disorders are experienced by nearly one billion people worldwide. Depression is one of the most common. Treatments exist, yet a devastating 75% of individuals suffering from depression do not receive adequate treatment. An emerging treatment strategy includes exploring the connection between mental health and nutrition, which includes the areas of gut health and nutrient deficiencies. Vitamin D is obtained through food, supplements, and sunlight. Many individuals are considered deficient (25[OH]D concentrations < 12 ng/mL) or insufficient (25[OH]D concentrations < 20 ng/mL). Purpose: This study aimed to explore mental and gastrointestinal (GI) health using surveys and lipopolysaccharide binding protein (LBP) concentrations, a biomarker of GI health, in individuals considered 25(OH)D deficient (DEF) vs not deficient (N-DEF). Methods: This cross-sectional study recruited physically active participants aged 18-45 years who underwent three evaluations in one visit. Health was assessed using surveys to evaluate mental health, GI symptoms, and vitamin D intake. Serum from fasting blood samples was used with an enzyme-linked immunosorbent assay to determine 25(OH)D and LBP concentrations. Unpaired t-tests were used to compare DEF vs N-DEF and significance was set at p < 0.05. Results: Thirty-two participants (mean age 25.3 ± 6.3 years) with mean and body fat percentage of 24.0% ± 10.7%, were placed into DEF (n=16) and N-DEF (n=16) categories. Interestingly, five of the 16 participants in DEF (31%) showed some level of depression (scores ranging from mild to severe) and only two of the 16 participants in N-DEF iv (13%) scored positively in the depression category (scores ranging from mild to moderate). Additionally, the participant with the lowest 25(OH)D concentration (5.42 ng/mL) was the only participant to meet the “severe” depression category criteria, with a score of 24 compared to other participants who scored within 0-16. Also, the only participant who scored “severe” in the stress category, was in the bottom 20% of 25(OH)D concentrations. As for GI health, the difference between average GI scores and average serum LBP concentrations between the groups were not statistically significant. Conclusion: There were no significant differences between DEF and N-DEF in perceived depression (p = 0.16), anxiety (p = 1.0), stress (p = 0.96), GI symptoms (P values ranged from 0.27 to 1.00), nor in LBP concentrations (p = 0.77). Funding: Support was received from the Graduate Student Association and College of Natural Health Sciences at the University of Northern Colorado.

Small Stream Restoration In The Piedmont Of South Carolina: Comparison Of Evaluation Tools And Water Quality’S Effects On Salamanders, Camryn Lachica

All Theses

For many years, the United States Army Corps of Engineers (USACE) used the Guidelines for Preparing a Compensatory Mitigation Plan worksheets to guide pre-restoration evaluation and determine post-restoration mitigation credits in South Carolina. Recently, the USACE in South Carolina transitioned to the Stream Quantification Tool (SQT), which provides a more comprehensive assessment framework. Our first objective was to compare these assessment methodologies across different landscape types to determine what the SQT adds to mitigation calculations that were not considered in prior worksheets. We evaluated 16 streams in the Piedmont of South Carolina, with four replicates each of forested, suburban, urban, …

Ecological And Social Resilience In Wildfire-Prone Communities, Melissa Burnett

All Theses

Climate projections suggest extreme weather variability, introducing extremely wet years, followed by years with extreme drought. These weather conditions are creating fire weather conducive to increasing wildfires across the southeast over the next century, which can have extreme ecological consequences. The Appalachian Mountains historically had some of the highest fire frequencies in North America but have been subjected to decades of fire suppression and prevention policies, resulting in an environment subject to more high-severity wildfires. The fall of 2016 was one of the driest seasons on record in this region and resulted in intense and destructive fires in the southeastern …

Polyphenols For The Mitigation Of Vascular Calcification; In Vitro And In Vivo Studies, Abdullah Altuhami

All Theses

Globally, cardiovascular diseases, in most cases associated with calcification, are the main cause of death. However, currently, the only effective cure is to undergo surgery to augment or receive a healthy donor heart, which could be very difficult due to the long waiting list and the associated risks. The possibility of body rejection of the foreign organs is attributed to immunoreaction or the risk of infection, since the donor must be on immunosuppressant drugs that lower the body's immunity and facilitate the body's acceptance of the new organ as one of its own. Taking that into consideration, using tissue-engineered vascular …

Assessing Grafted Triploid Watermelon And Yellow Nutsedge Growth In Saline Agroecosystems, Joseph F. Bazzle

All Theses

In an effort to better understand how saltwater intrusion events will impact watermelon growers a field trial was conducted to study how saline irrigation water will impact weed growth and seedless watermelon productivity at a joint Clemson University and USDA ARS facility. Weed management has always been a hurdle in vegetable crop production systems, requiring extensive labor even in a conventional setup. For organic growers, often the only economical approach is a combination of mechanical weed control techniques, including plastic mulches, tarps, and hand weeding. For watermelon growers, plastic mulch remains the most effective form of organic weed control available. …

Large Scale Deletion And Rebalancing Within The K1c Kafirin Family In Sorghum, Tyler W. Ferris

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

Sorghum bicolor (L.) Monech (sorghum) is cultivated as food for humans and livestock and is valued for its low input requirements. However, sorghum grain protein is deficient in the essential amino acid lysine and has poor protein digestibility because of the abundance of proline-rich kafirins that constitute >70% of proteins that form low-digestibility protein bodies. To reduce kafirin expression in the endosperm, and elicit wholesale proteome rebalancing to increase non-kafirin proteins, a single-guide RNA (sgRNA) Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR/Cas9) construct was previously used to target members of the highly-repetitive alpha-kafirin family, k1C in RTx430 sorghum. The …

Plant Nutrient Interactions In High-Yielding Soybean Environments, Victoria Inklman

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

Plant nutrient demands and limitations are usually studied individually by nutrient. Here, we investigated how nitrogen (N) limitation in high-yielding soybean environments affects the uptake, removal, and residual of other plant macro- and micronutrients. The objective of this study was to quantify the uptake, removal, and residual levels of soybean macro- and micronutrients under N-limited conditions and to identify nutrient priorities for high-yielding soybean systems. Aboveground plant samples at physiological maturity were collected in 19 high-yielding soybean fields with N limitation across the state of Nebraska. Reference plots with ample N supply were included within each field to compare macro- …

Crop, Soil Nutrient, And Soil Health Responses Within Integrated Crop And Livestock Systems, Alyssa K. Hall

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

We evaluated the influences of grazing livestock on crop production, soil nutrients, and soil health indicators of integrated crop livestock systems using three experiments during a seven-yr. period. Objectives were to (1) determine livestock grazing and cropping system effects on crop yield and soil properties across six yr. in corn-soybean (C-S) and wheat-corn-soybean (W-C-S) systems with and without periodic composted manure application, (2) explore seasonal variation in soil nutrient patterns over two yr., and (3) measure residual responses for corn grain yield plus soil health indicators in yr. seven following a six-yr. study. In experiment 1, neither livestock grazing ( …

Developing Targets To Control Multiple Pest Fly Species: Violet Polyester Targets Effectively Attract Tsetse (Diptera: Glossinidae), Stable Flies (Diptera: Muscidae), And House Flies (Diptera: Muscidae), Michael N. Okal, Sheillah J. Akinyi, Roger D. Santer

All Peer-Reviewed Publications

Tsetse (Glossina spp.), stable (Stomoxys spp.), and house flies (Musca domestica L.) impact humans and animals through bites and/or disease transmission. Tsetse are controlled using insecticide-coated fabric targets that are traditionally blue and/or black, but a violet polyester has now been engineered for greater attractiveness. Here, we investigate whether violet targets are also effective against stable and house flies. We sampled flies by electrocution at 1.0 (H) × 0.5 m (W) targets in Kenya, comparing catches at violet targets, and blue and black targets made from polyesters used in commercial traps and targets. Catches of female but not male Glossina …

Effect Of Amino Acid Derivatives And Polyphenol Supplementation On Skeletal Muscle Growth In-Vitro And In-Vivo, Gabriella C. Iheanacho

All Theses

Background

Satellite cells (SCs) are myogenic precursor cells that play a crucial role in muscle growth, and their activity can be influenced by nutrient supplementation. Muscle growth can also be stimulated using growth-promoting hormones; however, there are no approved growth hormones for use in sheep in the United States (Qaid & Abdoun, 2022). This limitation highlights a need to identify alternative compounds that would serve as nutrient supplements to enhance muscle growth and thereby improve meat production. Amino acid derivatives such as guanidinoacetic acid (GAA) and 5-hydroxytryptophan (5-HTP), along with the polyphenol quercetin, are naturally derived compounds that have shown …

Post-Harvest Storage Of Fuzzy Cottonseed: Quality, Airflow Modeling, And Energy Use, Elijah T. Porter

All Theses

Fuzzy cottonseed is a valuable byproduct of the cotton ginning process. When cottonseed exits the cotton gin, it often retains high temperatures and moisture contents. Once in a storage facility, the cottonseed needs to be conditioned for safe storage. The overall objectives of this study were to analyze quality changes in cottonseed according to storage conditions, determine the airflow resistance properties of fuzzy cottonseed, develop a computational fluid dynamics (CFD) model of a representative cottonseed storage facility, and analyze cottonseed aeration fan strategies, runtimes, and costs. Changes in quality dictate the allowable storage time for cottonseed and are impacted by …

Association Between Gene Family Expansion And The Rapid Diversification Of Pleurocarpous Mosses, Meredith A. Cobb

All Theses

Mosses are the second most species-rich group of land plants. They represent a critical group for understanding the evolution and diversity of land plants. Mosses comprise two major groups, acrocarps and pleurocarps. Despite having a more recent evolutionary origin than acrocarps, pleurocarps are exceptionally diverse. The difference in species richness reflects a rapid species diversification, roughly coincident with the origin and diversification of flowering plants. The speciation events giving rise to pleurocarp diversity happened so rapidly, making it historically difficult to produce strongly supported phylogenies with which to test evolutionary hypotheses. One such hypothesis is whether large-scale changes at the …

Determining The Impact Of Surface Roughness On Disinfection Efficacy Of Commercial Products Against Pseudomonas Aeruginosa And Staphylococcus Aureus Wet Surface Biofilms, Kayley Stallings

All Theses

Biofilms are resistant to many stressors including disinfectant treatments. Disinfection may be further complicated by biofilms formed on damaged surfaces, as the damaged parts provide bacteria a better place to attach and grow. To better understand the risks, a new method to standardize surface scratching, to emulate worn surfaces via surface roughness changes was developed. These surfaces were used to grow biofilms with an adapted standardized EPA method to determine disinfection efficacy differences on scratched and non-scratched high-density polyethylene (HDPE) and stainless steel (SS) coupons treated with commercial disinfectants [hypochlorite (CL)-based, hydrogen peroxide (HP)-based, and quaternary ammonium (QA)-based]. Post-80 grit …

Restoring A Longleaf Pine Savanna In The Wiregrass Gap: Community Responses To Post-Harvest Slash Manipulation, Eva Purcell

All Theses

Now reduced to just a fraction of their historical range, Longleaf pine savannas in the southeastern United States are home to a wide array of species, some of which are threatened or endemic. These characteristics have inspired widespread restoration initiatives in recent decades, accompanied by an expanding literature on how management techniques affect restoration outcomes. However, research is lacking in a unique region of longleaf pine’s range, where the dominant fire-carrying grasses are different: the Wiregrass Gap. This study investigated the effects of three different slash manipulation treatments on restoration outcomes of a Wiregrass Gap longleaf pine savanna. Specifically, we …

Night-Time Warming And Prey Availability Interact To Influence Physiology In Prairie Lizards (Sceloporus Consobrinus), Allison R. Litmer, Morgan K. Pelley, Steven J. Beaupre

Biological Sciences Faculty Publications and Presentations

Among ectotherms, temperature and food availability are drivers of individual and population characteristics. Increasing night-time temperatures due to climate change can increase energetic demands, potentially amplified or mitigated by prey consumption. Few studies examine night-time temperatures specifically, and consequences of co-occurring changes in the abiotic and biotic environment. Thus, we examined interactions between warming night-time temperatures and prey availability (as a proxy of foraging time and effectiveness), and how they affect food consumption, digestive passage time, metabolizable energy intake (MEI), assimilated energy, and fecal and urate production in a model organism, prairie lizards (Sceloporus consobrinus). Three temperature treatments (current conditions, …

Sex Differences In The Risk Of Developing Alzheimer Disease, Cognitive Trajectories, And Relationships Between Cognition And Pathological Burden, Carling G. Robinson

Arts & Sciences Graduate Student Theses and Dissertations

Prior work suggests females may develop Alzheimer disease (AD) dementia at a higher rate than males, and that this effect may interact with apolipoprotein (APOE) ε4 genotype. However, this work has often been limited by imprecise clinical diagnoses and a lack of AD biomarkers. In addition to the frequency of dementia, there are mixed reports on whether sex impacts rates of cognitive decline. Further, females consistently exhibit greater accumulation of AD pathological biomarkers, particularly tau, than males. It has been theorized that females initially demonstrate resilience to AD pathology, maintaining cognitive functioning longer than males, but experiencing a steeper cognitive …

The Future Research Direction Of Cgiar: Lessons Learned From One Cgiar, Katie Loethen

Graduate Theses and Dissertations

Since its founding in 1971, CGIAR (formerly the Consultative Group on International Agricultural Research) has been at the forefront of agricultural innovation, credited with launching the Green Revolution and delivering 1.78 trillion USD in net present value (NPV) benefits globally, particularly in low- and middle-income countries. Despite these accomplishments, CGIAR now faces internal and external pressures that threaten its future impact. The 2019 reorganization into “One CGIAR” aimed to enhance coordination but has been criticized for adding bureaucracy and reducing scientific autonomy. Simultaneously, public funding for agricultural research is shrinking, while private sector investment often overlooks low-margin, high-need areas central …

Tree Rings And The Broader Ocean-Atmospheric Circulation In The Highland Himalayas, Sanjaya Bhandari

All-Inclusive List of Electronic Theses and Dissertations

Climate change has altered tree-growth patterns and resulted in higher sea-surface temperatures across the planet. The Himalayan biome is one of the most vulnerable areas in the world to climate change because it has caused changes in forests’ growth and glaciers’ retreat. Dendrochronology has been used to understand the impact of climate change on tree growth and for climate reconstruction. In this dissertation, I discuss the growth of trees in the highlands of the eastern, central, and western Himalayas for the last 500 years and relate these patterns to the present global warming scenario and broad-scale climate modes. I reconstructed …

In Vitro Assessment Of The Antihistomonal Activity Of Methyl Jasmonate And Jasmonic Acid, Mckayla B. Williams

Poultry Science Undergraduate Honors Theses

Histomonas meleagridis is a protozoan parasite and the causative agent of histomonosis in gallinaceous birds. There are currently no approved prevention or treatment options available for histomonosis control in the United States. Mortality in affected turkey flocks can exceed 80% which highlights the urgent need for research investigating novel strategies to mitigate histomonosis in the field. The objective of this study was to evaluate the in vitro antihistomonal and antibacterial effects of of methyl jasmonate (MeJA) and jasmonic acid (JA), two plant-derived compounds, in a xenic culture of H. meleagridis. Assays were conducted using cultured H. meleagridis (PHL strain) treated …

Small Angle X-Ray Scattering Studies Of Collagenase H Mutant, Colh-E416q, Madelyn Millsap

Graduate Theses and Dissertations

Collagenase H (ColH) from Hathewaya histolytica plays a central role in collagen degradation through endopeptidase and carboxytripeptidase reactions. To better understand how its domain architecture supports these functions, we examined the solution structure of a catalytically inactive mutant, ColH-E416Q, using small-angle X-ray scattering (SAXS). The E416Q mutant is catalytically inactive because the glutamate residue at position 416, which normally functions as a general acid/base during catalysis, is replaced by glutamine—an amide that cannot donate or accept protons effectively, thus disabling the proton transfer steps essential for peptide bond hydrolysis. SAXS results indicate that the E416Q substitution leaves overall domain architecture …

Improved Autofluorescence Lifetime Decay Analysis For Identification Of Cellular Autofluorescence Biomarkers For Label-Free, Single-Cell Assessment Of Mitochondrial Membrane Potential, Olivia Isabel Kolenc

Graduate Theses and Dissertations

Optical imaging of metabolism using the autofluorescence of the metabolic cofactors NADH, NADPH, and FAD has a wide range of sensitivities and the capability to collect a great deal of metabolic information. Multiphoton microscopy (MPM) is a non-invasive, label-free optical imaging technique capable of performing fluorescence lifetime imaging (FLIM) using time correlated single photon counting (TCSPC). However, autofluorescence FLIM presents a challenge in collecting sufficient photons to provide adequate signal to noise ratios (SNR) for analysis. Additionally, the specificity of autofluorescence biomarkers of metabolism has not been well-defined. Contextualizing these autofluorescence measures using established functional biomarkers can improve interpretability of …

Host-Virus Interaction Dynamics Using Sulfolobus Spindle-Shaped Virus And Host Sulfolobales System, Yeasin Ahmed

Graduate Theses and Dissertations

The Sulfolobus Spindle-shaped virus (SSV) is among the most studied archaeal viruses, particularly in extreme environments. This virus predominantly infects multiple Crenarchaea from the Sulfolobaceae family. These hosts thrive in extreme environmental conditions, such as sulfuric hot springs, with a pH of 2 to 4 and a temperature of 76-80˚C. Sulfolobales exhibit a wide geographical distribution across volcanic hot springs. The Sulfolobus Spindle-shaped Virus (SSV), encompassing strains such as SSV1 and SSV8, employs a non-lytic replication strategy in hosts belonging to the order Sulfolobales. The SSV-Sulfolobales system can be cultured in liquid and gellan gum solid media. A comprehensive study …

The Role Of Cleavage And Polyadenylation Spcific Factor 6 (Cpsf6) In Hematopoiesis, Fengxi Ye

Dissertations and Theses (Open Access)

Cleavage and polyadenylation specific factor 6 (Cpsf6) translocation is frequently reported in APLL, which is Acute Promyelocytic Leukemia (APL)-like acute myeloid leukemia (AML) and other types of blood diseases associated with abnormal hematopoiesis. CPSF6 is a subunit of the Cleavage Factor I mammalian (CFIm) complex, which regulates post-transcriptional alternative polyadenylation (APA) of pre-mRNAs. Previous research indicated that Cpsf6 plays an essential role in alternative polyadenylation, development, and tumorigenesis. However, the role of Cpsf6 in hematopoiesis is unknown. Given its roles in APA, development and cancer, we hypothesize that Cpsf6 plays a critical role in hematopoiesis and that its …

Coastal Transition Zone Development Effects On Salt Marsh Ecology, Amanda Mei Pysher

Electronic Theses and Dissertations

The coastal transition zone (CTZ) is a regional gradient linking terrestrial and marine systems, comprising of the terrestrial upland, the marsh-upland ecotone, and estuarine salt marshes. Along all US coastlines, including the South Carolina (SC) coast from Little River to Georgetown, increases in anthropogenic development of terrestrial uplands have altered the historically established vegetation, and various physical, chemical, biological, and geological gradients. Despite the CTZ's ecological importance, the trickle-down effects of terrestrial upland development on associated high marsh habitats remain understudied. Data were collected from developed (DEV) and undeveloped (UND) shorelines across three SC estuarine inlets. Multilevel modeling (MLM) was …