Physical Sciences and Mathematics Commons^™

Experimental Analysis Of Nonlinear Wave Propagation In Bistable Mechanical Metamaterials With A Defect, Samuel R. Harre

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Mechanical metamaterials built up of compliant units can support the propagation of linear and nonlinear waves. A popular architecture consists of a one-dimensional chain of bistable elements connected by linear springs. This type of chain can support nonlinear transition waves that switch each element from one stable state to the other as they propagate along the chain. One way to manipulate the propagation of such waves is via introduction of a local inhomogeneity, i.e., a defect in the otherwise periodic chain. Recent analytical and numerical work has shown that based on its initial velocity, a transition wave may be reflected, …

The Evaluation Of Feed Additives On Reducing Enteric Methane Production From Cattle, Reba L. Colin

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

Environmental sustainability can be positively impacted by the inclusion of feed additives to reduce enteric methane production from cattle. Methane production can be affected by feed additives that either alter the rumen environment or act as methanogenesis inhibitors. A reduction in methane from cattle can contribute to meeting carbon neutrality.

A metabolism study was conducted to evaluate Alga 1.0, a product containing bromoform, fed to cattle to evaluate the effects on gas emissions. Treatments were (0, 69, or 103 g/d Alga 1.0) fed in a corn-based diet. Headbox-style indirect calorimeters were used to measure gas emissions. Feeding Alga 1.0 linearly …

Enhanced Privacy-Enabled Face Recognition Using Κ-Identity Optimization, Ryan Karl

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

Facial recognition is becoming more and more prevalent in the daily lives of the common person. Law enforcement utilizes facial recognition to find and track suspects. The newest smartphones have the ability to unlock using the user's face. Some door locks utilize facial recognition to allow correct users to enter restricted spaces. The list of applications that use facial recognition will only increase as hardware becomes more cost-effective and more computationally powerful. As this technology becomes more prevalent in our lives, it is important to understand and protect the data provided to these companies. Any data transmitted should be encrypted …

Co2 Storage Capacity And Injectivity Of Stacked Carbonates Of The Pennsylvanian And Permian In Western Nebraska, Lateef Lawal

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Geological carbon storage (GCS) is a critical aspect of carbon capture and storage (CCS) in which captured CO₂ from power plants and industrial processes is injected and stored securely underground. Potential subsurface rock formations include saline aquifers, depleted oil and gas reservoirs, unmineable coal seams and volcanic rocks. GCS technology has been proven in the United States and many other parts of the world as a net-zero carbon emission strategy to mitigate the current climate crisis of our planet. Unlike other states such as Wyoming, GCS projects are still in the early phases in Nebraska. The goal of this …

Characterization Of Interlayer Laser Shock Peening During Fused Filament Fabrication Of Polylactic Acid (Pla), Fabien Denise

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The field of additive manufacturing (AM) has gained a significant amount of popularity due to the increasing need for more sustainable manufacturing techniques and the adaptive development of complex product geometries. The problem is that AM parts routinely exhibit flaws or weaknesses that affect functionality or performance. Over the years, surface treatments have been developed to compensate certain flaws or weaknesses in manufactured products. Combining surface treatments with the modularity of additive manufacturing could lead to more adaptable and creative improvements of product functions in the future. The current work evaluates the feasibility of pursuing a new research axis in …

In Situ Water Sensing Systems: Research On Advancements In Environmental Monitoring, Abigail Seibel

Honors Theses

In this work, two sensing systems were researched in order to improve in situ environmental monitoring. The first is a pH and Total Alkalinity sensor used to determine these characteristics of sea water. I explored the facets of this sensor over a 7-week internship with Dr. Ellen Briggs in her lab in summer of 2023. The second is a more holistic sensing system that reads temperature, turbidity, and pressure used for studying environmental characteristics of Alaskan bever ponds. Both systems were developed in close collaboration with scientists who are collecting data to better understand the impacts of climate change. Better …

Uv Dynamics Of Different Ring Molecules Studied By Ultrafast Electron Diffraction, Sajib Kumar Saha

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

Understanding natural light-induced phenomena requires a direct viewing of atomic motion during structural evolution, which, in turn, facilitates controlling and manipulating these light-induced processes. Ultrafast Electron Diffraction (UED) is a structure-sensitive technique that can probe electronic and nuclear dynamics at sub-angstrom spatial and femtosecond time scales. UED has become a vital tool for studying photo-induced molecular dynamics and underlying science. Organic ring systems are prevalent in biology, materials, and pharmaceuticals. Their synthesis and transformation are fundamental in synthetic chemistry, influencing various fields. We used UV photons to photo-excite different cyclic molecules and investigated their photo-dynamics using gas phase UED. The …

Capturing The Generation And Structural Transformations Of Molecular Ions, Jun Heo, Doeyeong Kim, Alekos Segalina, Hosung Ki, Doo-Sik Ahn, Seonggon Lee, Jungmin Kim, Yongjun Cha, Kyung Won Lee, Jie Yang, J. Pedro F. Nunes, Xijie Wang, Hyotcherl Ihee

Department of Physics and Astronomy: Faculty Publications

Molecular ions are ubiquitous and play pivotal roles^1–3 in many reactions, particularly in the context of atmospheric and interstellar chemistry^4–6. However, their structures and conformational transitions^7,8, particularly in the gas phase, are less explored than those of neutral molecules owing to experimental difficulties. A case in point is the halonium ions^9–11, whose highly reactive nature and ring strain make them short-lived intermediates that are readily attacked even by weak nucleophiles and thus challenging to isolate or capture before they undergo further reaction. Here we show that megaelectronvolt ultrafast electron diffraction (MeV-UED)^12–14, …

Prediction Of Giant Tunneling Magnetoresistance In Ruo2/Tio2/Ruo2 (110) Antiferromagnetic Tunnel Junctions, Yuan-Yuan Jiang, Zi-An Wang, Kartik Samanta, Shu-Hui Zhang, Rui-Chun Xiao, W. J. Lu, Y. P. Sun, Evgeny Y. Tsymbal, Ding-Fu Shao

Department of Physics and Astronomy: Faculty Publications

Using first-principles quantum-transport calculations, we investigate spin-dependent electronic and transport properties of antiferromagnetic tunnel junctions (AFMTJs) that consist of (110)-oriented antiferromagnetic (AFM) metal RuO₂ electrodes and an insulating TiO₂ tunneling barrier. We predict the emergence of a giant tunneling magnetoresistance (TMR) effect in a wide energy window, a series of barrier layer thicknesses, and different interface terminations, indicating the robustness of this effect. We show that the predicted TMR cannot be explained in terms of the global transport spin-polarization of RuO₂ (110) but is well understood based on matching the momentum-dependent spin-polarized conduction channels of the two …

Differentiating By Prime Numbers, Jack Jeffries

Department of Mathematics: Faculty Publications

It is likely a fair assumption that you, the reader, are not only familiar with but even quite adept at differentiating by x. What about differentiating by 13? That certainly didn’t come up in my calculus class! From a calculus perspective, this is ridiculous: are we supposed to take a limit as 13 changes? One notion of differentiating by 13, or any other prime number, is the notion of p-derivation discovered independently by Joyal [Joy85] and Buium [Bui96]. p-derivations have been put to use in a range of applications in algebra, number theory, and arithmetic geometry. Despite the wide range …

3dgaunet: 3d Generative Adversarial Networks With A 3d U-Net Based Generator To Achieve The Accurate And Effective Synthesis Of Clinical Tumor Image Data For Pancreatic Cancer, Yu Shi, Hannah Tang, Michael J. Baine, Michael A. Hollingsworth, Huijing Du, Dandan Zheng, Chi Zhang, Hongfeng Yu

School of Computing: Faculty Publications

Pancreatic ductal adenocarcinoma (PDAC) presents a critical global health challenge, and early detection is crucial for improving the 5-year survival rate. Recent medical imaging and computational algorithm advances offer potential solutions for early diagnosis. Deep learning, particularly in the form of convolutional neural networks (CNNs), has demonstrated success in medical image analysis tasks, including classification and segmentation. However, the limited availability of clinical data for training purposes continues to represent a significant obstacle. Data augmentation, generative adversarial networks (GANs), and cross-validation are potential techniques to address this limitation and improve model performance, but effective solutions are still rare for 3D …

Pathogenicity In Chickens And Turkeys Of A 2021 United States H5n1 Highly Pathogenic Avian Influenza Clade 2.3.4.4b Wild Bird Virus Compared To Two Previous H5n8 Clade 2.3.4.4 Viruses, Mary J. Pantin-Jackwood, Erica Spackman, Christina Leyson, Sungsu Youk, Scott A. Lee, Linda M. Moon, Mia K. Torchetti, Mary L. Killian, Julianna B. Lenoch, Darrell R. Kapczynski, David E. Swayne, David L. Suarez

United States Department of Agriculture Wildlife Services: Staff Publications

Highly pathogenic avian influenza viruses (HPAIVs) of subtype H5 of the Gs/GD/96 lineage remain a major threat to poultry due to endemicity in wild birds. H5N1 HPAIVs from this lineage were detected in 2021 in the United States (US) and since then have infected many wild and domestic birds. We evaluated the pathobiology of an early US H5N1 HPAIV (clade 2.3.4.4b, 2021) and two H5N8 HPAIVs from previous outbreaks in the US (clade 2.3.4.4c, 2014) and Europe (clade 2.3.4.4b, 2016) in chickens and turkeys. Differences in clinical signs, mean death times (MDTs), and virus transmissibility were found between chickens and …

Ict Application And Information Service Delivery In South-West Nigeria’S Public Polytechnic Libraries, Omolabake Eunice Akinyemi, Toyosi Rachel Afolabi

Library Philosophy and Practice (e-journal)

Teh study dwells on teh application of information and communication technology (ICT) for enhancing information service delivery in South-West Nigeria’s public polytechnic libraries. Teh study's goal is to determine teh extent of ICT application in polytechnic libraries. For teh study, a descriptive survey research design was adopted. Teh population of teh study consists of all teh library personnel in South-West Nigeria’s public polytechnic libraries. Teh instrument for gathering data was a questionnaire. Descriptive statistics such as mean, standard deviation, frequency count, and simple percentage were used to analyse teh data. Teh hypothesis was tested by Pearson Moment Product Correlation at …

Enhancing Academic Library Service Delivery Using Artificial Intelligence (Ai), Omolabake Akinyemi

Library Philosophy and Practice (e-journal)

Academic libraries are crucial parts of educational establishments coz they give lecturers and students access to a wealth of knowledge resources. dis article examines how artificial intelligence (AI) can change academic libraries and raise teh calibre and TEMPeffectiveness of service delivery in reference, circulation, cataloguing and classification to meet teh changing needs of library users. Examples of AI applications in academic libraries are given in teh study. Teh study explores teh possible benefits of AI in academic library and impediments to its integration. Teh study concludes dat teh use of AI in academic libraries is a big step toward better …

Raccoon Spatial Ecology In The Rural Southeastern United States, Jacob E. Hill, Madison L. Miller, James L. Helton, Richard B. Chipman, Amy T. Gilbert, James C. Beasley, Guha Dharmarajan, Olin E. Rhodes Jr.

United States Department of Agriculture Wildlife Services: Staff Publications

The movement ecology of raccoons varies widely across habitats with important implications for the management of zoonotic diseases such as rabies. However, the spatial ecology of raccoons remains poorly understood in many regions of the United States, particularly in the southeast. To better understand the spatial ecology of raccoons in the southeastern US, we investigated the role of sex, season, and habitat on monthly raccoon home range and core area sizes in three common rural habitats (bottomland hardwood, upland pine, and riparian forest) in South Carolina, USA. From 2018–2022, we obtained 264 monthly home ranges from 46 raccoons. Mean monthly …

Raccoon Spatial Ecology In The Rural Southeastern United States, Jacob E. Hill, Madison L. Miller, James L. Helton, Richard B. Chipman, Amy Gilbert, University Of Georgia, Guha Dharmarajan, Olin E. Rhodes Jr.

United States Department of Agriculture Wildlife Services: Staff Publications

The movement ecology of raccoons varies widely across habitats with important implications for the management of zoonotic diseases such as rabies. However, the spatial ecology of raccoons remains poorly understood in many regions of the United States, particularly in the southeast. To better understand the spatial ecology of raccoons in the southeastern United States, we investigated the role of sex, season, and habitat on monthly raccoon home range and core area sizes in three common rural habitats (bottomland hardwood, upland pine, and riparian forest) in South Carolina, USA. From 2018–2022, we obtained 264 monthly home ranges from 46 raccoons. Mean …

Relativistic Ultrafast Electron Diffraction At High Repetition Rates, K. M. Siddiqui, D. B. Durham, F. Cropp, F. Ji, S. Paiagua, C. Ophus, N. C. Andresen, L. Jin, J. Wu, S. Wang, X. Zhang, W. You, M. Murnane, Martin Centurion, X. Wang, D. S. Slaughter, R. A. Kaindl, P. Musumeci, A. M. Minor, D. Filippetto

Martin Centurion Publications

The ability to resolve the dynamics of matter on its native temporal and spatial scales constitutes a key challenge and convergent theme across chemistry, biology, and materials science. The last couple of decades have witnessed ultrafast electron diffraction (UED) emerge as one of the forefront techniques with the sensitivity to resolve atomic motions. Increasingly sophisticated UED instruments are being developed that are aimed at increasing the beam brightness in order to observe structural signatures, but so far they have been limited to low average current beams. Here, we present the technical design and capabilities of the HiRES (High Repetition-rate Electron …

Probing The Electroweak Phase Transition With Exotic Higgs Decays, Marcela Carena, Jonathan Kozaczuk, Zhen Liu, Tong Ou, Michael J. Ramsey-Musolf, Jessie Shelton, Yikun Wang, Ke-Pan Xie

Department of Physics and Astronomy: Faculty Publications

An essential goal of the Higgs physics program at the LHC and beyond is to explore the nature of the Higgs potential and shed light on the mechanism of electroweak symmetry breaking. An important class of models alter the thermal history of electroweak symmetry breaking from the predictions of the Standard Model (SM). This paper reviews the existence of a region of parameter space where a strong first-order electroweak phase transition is compatible with exotic decays of the SM-like Higgs boson. A dedicated search for exotic Higgs decays can actively explore this framework at the Large Hadron Collider (LHC), while …

An Empirical Examination Of The Environmental Variability That Impacted Supercell Evolution, Longevity, And Severe Weather Production On 22 May 2019 In Oklahoma, Kyle D. Pittman

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Mesoscale environmental heterogeneity can have significant impacts on thunderstorm organization, evolution, longevity, and severe weather production. This study examines the 22 May 2019 thunderstorm event in Oklahoma, where a relatively broad area of strong instability and vertical wind shear existed along a synoptic boundary and in the open warm sector that would seem to support long-lived supercells and tornadoes. There were two particularly dangerous situation (PDS) tornado watches issued during the event, but few severe reports and no tornadoes formed in the watch that covered the southwestern portion of the state. Several tornadic supercells and many more severe reports occurred …

Precipitation And Greenness In Pastoral Lands Of East Turkana, Kenya, Paul Akpejeluh

School of Natural Resources: Dissertations, Theses, and Student Research

Pastoralism has long supported livelihoods and provided essential ecosystem services in landscapes of East Africa. Vegetation productivity is central to the functioning of pastoral systems but may be affected by changes in climate and landuse. Vegetation monitoring is important for understanding the effects of global change in pastoral lands; however, it can be time and resource intensive. Remote sensing provides opportunities for efficient multi-scale monitoring of vegetation and climatic drivers. In this thesis, I explore the utility of satellite and UAV remote sensing for monitoring vegetation and precipitation trends and relationships in the East of Lake Turkana Region of northern …

Connecting The Nebraska Water Quality Index To The Aquatic Microbial Community Of The North Platte River Basin, Nebraska, Paula R. Guastello

School of Natural Resources: Dissertations, Theses, and Student Research

The Nebraska Water Quality Index, under development by the Nebraska Department of Environment and Energy, summarizes in a single value eight environmental parameters that have been monitored in Nebraska for nearly 20 years. Water quality parameters including those used in the Nebraska Water Quality Index have been shown in previous studies to impact bacterial growth. As such, this index has the potential to correlate with the freshwater microbial community. Here, I relate the Nebraska Water Quality Index to microbial community composition and structure using 16S rRNA gene amplicon sequence data collected from the North Platte River Basin, Nebraska. This index …

Motif-Cluster: A Spatial Clustering Package For Repetitive Motif Binding Patterns, Mengyuan Zhou

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

Previous efforts in using genome-wide analysis of transcription factor binding sites (TFBSs) have overlooked the importance of ranking potential significant regulatory regions, especially those with repetitive binding within a local region. Identifying these homogenous binding sites is critical because they have the potential to amplify the binding affinity and regulation activity of transcription factors, impacting gene expression and cellular functions. To address this issue, we developed an open-source tool Motif-Cluster that prioritizes and visualizes transcription factor regulatory regions by incorporating the idea of local motif clusters. Motif-Cluster can rank the significant transcription factor regulatory regions without the need for experimental …

Modeling Overdraft-Driven Nitrate Transport In Shallow Wells For Mitigation And Scenario Planning, Jonathan Cronk

Department of Biological Systems Engineering: Dissertations and Theses

In Nebraska, average nitrate concentrations in groundwater have doubled since 1974, making water quality management more important than ever. As droughts, heat waves, and floods become more common climate events, understanding their impacts will be necessary to make informed management decisions. Emerging literature describes that drought correlates to an increase in the concentration of nitrate-N at domestic and irrigation wells, however the relative contributions of the mechanisms thought to be responsible is currently unknown.

This research assessed the impact of recharge and pumping rate changes as two mechanisms affecting nitrate-N concentration during drought, assessed the relationship between well depth and …

Hydroxyapatite-Based Coatings On Silicon Wafers And Printed Zirconia, Antoine Chauvin

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Dental surgery needs a naturally attract implant design that can ensure both osseointegration and soft tissue integration. Hydroxyapatite (HAp), the main mineral constituent of dentine and tooth enamel, is commonly used as a coating component, notably for overlaying titanium– or ceramics–based implants. This thesis aims to investigate the behavior of a HAp-based coating, specifically designed to be compatible with a porous substrate. Coating layers are made by sol–gel dip coating by immersion of porous substrates made by additive manufacturing into solutions of HAp, having been mixed with polyethyleneimine (PEI), to improve the adhesion of HAp on the substrate. First, the …

Convolutional Neural Network-Based Gene Prediction Using Buffalograss As A Model System, Michael Morikone

Complex Biosystems PhD Program: Dissertations

The task of gene prediction has been largely stagnant in algorithmic improvements compared to when algorithms were first developed for predicting genes thirty years ago. Rather than iteratively improving the underlying algorithms in gene prediction tools by utilizing better performing models, most current approaches update existing tools through incorporating increasing amounts of extrinsic data to improve gene prediction performance. The traditional method of predicting genes is done using Hidden Markov Models (HMMs). These HMMs are constrained by having strict assumptions made about the independence of genes that do not always hold true. To address this, a Convolutional Neural Network (CNN) …

Comparison Of Ceneb And Cohyst Hydrologic Models Within A Common Domain In Central Nebraska, William R. Moak

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The Nebraska Department of Natural Resources (NDNR) has developed several hydrologic models to help effectively manage water resources in the state. These models guide water managers to allocate surface and groundwater supplies to a range of uses (irrigation, environmental protection, interstate water agreements) and evaluate the impacts of changes to the surface water-groundwater system (e.g., new wells, evolving recharge patterns). Two such models, the Central Nebraska (CENEB) model and the Cooperative Hydrology Study (COHYST) model cover north central and south central Nebraska, respectively, but the model domains overlap along a west-east strip between the Platte and Loup Rivers, enabling direct …

A Climatology Of Mesoscale Airmasses With High Theta-E, Charles J. Kropiewnicki

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

A Mesoscale Airmass with High Theta-E (MAHTE) is a narrow region of larger theta-e located on the cool side of an airmass boundary. MAHTEs typically possesses higher CAPE than the warm side of the boundary, creating a more favorable environment for severe convection. MAHTEs can also be characterized by larger low-level shear and lower LCLs and may also have a propensity for supporting tornadogenesis. The majority of MAHTE research to date has been comprised of case studies, and the prevalence of MAHTEs is not well understood. This project fills that knowledge gap by creating a climatology of MAHTE occurrence. This …

Skin Lipids Alone Enable Conspecific Tracking In An Invasive Reptile, The Argentine Black And White Tegu Lizard (Salvator Merianae), M. Rockwell Parker, Eric A. Tillman, Lauren A. Nazarian, Megan L. Barlowe, Julianna M. Lincoln, Bryan M. Kluever

United States Department of Agriculture Wildlife Services: Staff Publications

Locating potential mates in non-native habitats is one of the most important challenges faced by invasive vertebrate species. The Argentine black and white tegu lizard (Salvator merianae) is a major invasive reptile species in the contiguous United States and is rapidly expanding its range across Florida and the Southeast, in part due to inadequate management strategies and tools. Because a wide array of reptiles, especially squamates (snakes and lizards), have been well-studied for their reliance on chemical cues to locate conspecifics, our project aimed to isolate chemical cues from tegus and assess the ability of adult males and …

Osc-Co2: Coattention And Cosegmentation Framework For Plant State Change With Multiple Features, Rubi Quiñones, Ashok Samal, Sruti Das Choudhury, Francisco Muñoz-Arriola

School of Computing: Faculty Publications

Cosegmentation and coattention are extensions of traditional segmentation methods aimed at detecting a common object (or objects) in a group of images. Current cosegmentation and coattention methods are ineffective for objects, such as plants, that change their morphological state while being captured in different modalities and views. The Object State Change using Coattention-Cosegmentation (OSC-CO²) is an end-to-end unsupervised deep-learning framework that enhances traditional segmentation techniques, processing, analyzing, selecting, and combining suitable segmentation results that may contain most of our target object’s pixels, and then displaying a final segmented image. The framework leverages coattention-based convolutional neural networks (CNNs) and …

Pleistocene Bats (Late Irvingtonian And Late Rancholabrean) From Nuckolls And Sherman Counties, Nebraska, Nicholas J. Czaplewski, Richard George Corner

Transactions of the Nebraska Academy of Sciences and Affiliated Societies

We document rare finds of fossil bats from two localities representing the Pleistocene epoch in southern and central Nebraska, Albert Ahrens locality (No-104, late Irvingtonian age, Middle Pleistocene), Nuckolls County, and Litchfield (Sm-102, late Rancholabrean age, latest Pleistocene), Sherman County. The Albert Ahrens local fauna with strong boreal influence has produced two bats, Lasiurus cf. borealis and Cf. Myotis sp. The Litchfield local fauna, also showing a strong boreal influence, has yielded two bats, Eptesicus fuscus and Cf. Myotis, among a diverse Pleistocene fauna of small vertebrates and a pollen record indicating a boreal mixed conifer and deciduous woodland, …