Digital Commons Network^™

Fire And Human Management Of Late Holocene Ecosystems In Southern Africa, Benjamin Davies, Mitchell J. Power, David R. Braun, Matthew J. Douglass, Stella G. Mosher, Lynne J. Quick, Irene Esteban, Judith Sealy, John Parkington, J. Tyler Faith

School of Natural Resources: Faculty Publications

Globally, fire is a primary agent for modifying environments through the long-term coupling of human and natural systems. In southern Africa, control of fire by humans has been documented since the late Middle Pleistocene, though it is unclear when or if anthropogenic burning led to fundamental shifts in the region's fire regimes. To identify potential periods of broad-scale anthropogenic burning, we analyze aggregated Holocene charcoal sequences across southern Africa, which we compare to paleoclimate records and archaeological data. We show climate-concordant variability in mid-Holocene fire across much of the subcontinent. However, increased regional fire activity during the late Holocene (~2000 …

Secondary Science Teachers Use Of Models In Teaching And Learning About Earth’S Climate, Kimberly Carroll Steward

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

Global climate change (GCC) presents unprecedented global concerns, notably food supply limitations, unsustainable use of natural resources, and widespread environmental degradation. The International Panel on Climate Change (IPCC) reports a 0.85 °C increase in global average temperatures between 1880 and 2018 and a 50% increase in global carbon dioxide emissions since 1990 (Stocker et al., 2018). As a result of the urgency of the situation, there is a strong emphasis on empowering citizens through outreach and education. There is a need to adequately prepare the next generation of scientists, politicians, business leaders, and other people; it is crucial to foster …

Symbolic Power Containments In Singular Rings In Positive Characteristic, Eloísa Grifo, Linquan Ma, Karl Schwede

Department of Mathematics: Faculty Publications

The containment problem for symbolic and ordinary powers of ideals asks for what values of a and b we have I(a)⊆Ib. Over a regular ring, a result by Ein-Lazarsfeld-Smith, Hochster-Huneke, and Ma-Schwede partially answers this question, but the containments it provides are not always best possible. In particular, a tighter containment conjectured by Harbourne has been shown to hold for interesting classes of ideals - although it does not hold in general. In this paper, we develop a Fedder (respectively, Glassbrenner) type criterion for F-purity (respectively, strong F-regularity) for ideals of finite projective dimension over F-finite Gorenstein rings and use …

Impacts Of Physical Parameterization Schemes And Soil Moisture Initialization On Boundary Layer Evolution In The Weather Research And Forecasting (Wrf) Model, Grace Cutting

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

Numerical weather prediction (NWP) models have become a necessary addition to the atmospheric research community over the last several decades, and atmospheric modeling has been used internationally for numerous operational and research purposes. NWP models contain a vast number of combinations of physical and dynamical parameterization schemes; however, they are not always accurate in forecasting weather phenomena at a particular location, as different combinations of parameterization schemes represent differing conditions. Weather Research and Forecasting (WRF) model simulations were run to explore which of the commonly used planetary boundary layer (PBL) schemes best represented upper-air data (as well as PBL evolution) …

A Latent Class Analysis Of Personality Traits With Educational Attainment, Tyler Minter

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

The five-factor model of personality (extraversion, agreeableness, conscientiousness, neuroticism, openness to experience) is an empirically based personality model that has been utilized in multiple psychological assessments. Recent works have found Block & Block’s (1980) three personality profiles (resilient, overcontrolled, undercontrolled) within the context of the five-factor model. This study performed a latent class analysis using a short FFM assessment from the SAPA project, a free online personality test. The intention of this study was to replicate the three personality profiles within the five-factor model. Four latent classes were included in the final solution. Two of the three personality profiles emerged …

Towards Usable Environmental Information: A Case Study With The Santee Sioux Nation, Alexis Chavez

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

Across the United States (U.S.), Indigenous peoples have developed and implemented adaptation plans to improve their resilience to climate and weather disturbances. An essential component of these plans is to use environmental information effectively. Institutions like universities and government agencies usually provide this information, and its usability depends on the information’s quality and the relationships that establish its accessibility and validity. However, many studies have shown that much of this information is not usable for its intended users. Additionally, there has been little research into the issues that can affect Indigenous peoples’ usage of environmental information in the U.S. Therefore, …

Nonbreeding Season Survival And Habitat Selection Of Northern Bobwhite In Northeastern Colorado, Joseph M. Wolske

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

Northern bobwhites (Colinus virginianus) have experienced range-wide population declines. Recent harvest data from northeastern Colorado suggests bobwhite populations have declined and populations can be sensitive to adult nonbreeding season survival. We monitored 157 bobwhites in northeastern Colorado, on the northern periphery of the species’ range, for the 2019-2020 and 2020-2021 nonbreeding seasons to estimate nonbreeding season survival and habitat selection. We used known-fate survival models to assess any variation in survival between the winter stages of early-winter, mid-winter, and late-winter, as well as sex, age class, and mass at the time of capture. Survival varied among winter stages, …

Analysis Of Soil Change Across Nebraska, Trinity Baker

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

The world’s population is growing and an increasing populace requires more resources. These requirements place increasing pressure on the environment and the soil. Soils serve many important functions throughout the world. These functions range from offering a media for food production, providing a sink for organic carbon, nutrient cycling, and improving water quality. It is important to focus on the human impact on soils and their change over time.

For my research I examined how soils across Nebraska have changed over a time period of roughly 65 years. I sampled and analyzed 39 pedons from four Major Land Resource Areas …

Human Perception Of Exponentially Increasing Data Displayed On A Log Scale Evaluated Through Experimental Graphics Tasks, Emily Robinson

Department of Statistics: Dissertations, Theses, and Student Research

Log scales are often used to display data over several orders of magnitude within one graph. We conducted a series of three graphical studies to evaluate the impact displaying data on the log scale has on human perception of exponentially increasing trends compared to displaying data on the linear scale. Each study was related to a different graphical task, each requiring a different level of interaction and cognitive use of the data being presented. The first experiment evaluated whether our ability to perceptually notice differences in exponentially increasing trends is impacted by the choice of scale. Participants were shown a …

Production Of Polyhydroxybutyrate From Corn Fiber Using Paraburkholderia Sacchari, Twissa Mitra

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

Poly(3-hydroxybutyrate) (PHB) is one of the most broadly studied members of the polyhydroxyalkanoates (PHA) family. It is a fully biodegradable thermoplastic produced by microbial fermentation having properties similar to polypropylene. PHB has a market price that is three times higher than the cost of synthetic plastics. Substrate cost makes up 50 to 60 % of that cost; hence, researchers have been exploring various cheap natural resources with high carbohydrate content to be used as a substrate for PHB production.

In this study, corn fiber, a lignocellulosic biomass has been studied as an option for a substrate to produce PHB. This …

18s-Nemabase: Curated 18s Rrna Database Of Nematode Sequences, Kaitlin Gattoni, Eli M. S. Gendron, Rebeca Sandoval- Ruiz, Abigail Borgemeier, J. Parr Mcqueen, Rachel M. Shepherd, Dieter Slos, Tom Powers, Dorota L. Porazinska

Department of Plant Pathology: Faculty Publications

Nematodes are the most abundant and diverse animals on the planet but lack representation in biodiversity research. This presents a problem for studying nematode diversity, particularly when molecular tools (i.e., barcoding and metabarcoding) rely on well-populated and curated reference databases, which are absent for nematodes. To improve molecular identification and the assessment of nematode diversity, we created and curated an 18S rRNA database specific to nematodes (18S-NemaBase) using sequences sourced from the most recent publicly available 18S rRNA SILVA v138 database. As part of the curation process, taxonomic strings were standardized to contain a fixed number of taxonomic ranks relevant …

In Vivo Efficacy Of Pyrantel Pamoate As A Post-Exposure Prophylactic For Rat Lungworm (Angiostrongylus Cantonensis), John Jacob, Argon Steel, Lisa Kaluna, Steven Hess, Israel Leinbach, Carmen Antaky, Robert Sugihara, Lindsey Hamilton, Peter Follett, Kathleen Howe, Steven Jacquier, Supakit Wongwiwatthananukit, Susan Jarvi

United States Department of Agriculture Wildlife Services: Staff Publications

Rat lungworm (Angiostrongylus cantonensis) is a neurotropic nematode, and the leading cause of eosinophilic meningitis worldwide. The parasite is usually contracted through ingestion of infected gastropods, often hidden in raw or partially cooked produce. Pharmaceutical grade pyrantel pamoate was evaluated as a post-exposure prophylactic against A. cantonensis. Pyrantel pamoate is readily available over-the-counter in most pharmacies in the USA and possesses anthelmintic activity exclusive to the gastrointestinal tract (GIT). Administering pyrantel pamoate immediately after exposure should theoretically paralyze the larvae in the GIT, causing the larvae to be expelled via peristalsis without entering the systemic circulation. In this study, pyrantel …

Fermion-Induced Electroweak Symmetry Non-Restoration Via Temperature-Dependent Masses, Yu Hang Ng

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

Standard Model (SM) and many extensions of SM predict that the electroweak (EW) symmetry was restored in the early universe when the temperature was around 160 GeV. However, recent studies showed that the interactions between some new scalars and SU(2)_L Higgs doublet(s) can cause the EW symmetry to remain broken at temperatures well above the EW scale in certain renormalizable extensions of SM. In this study, we found that new fermions from renormalizable models can also induce this EW symmetry non-restoration effect, provided that they have the appropriate temperature-dependent masses. These masses can arise naturally from the interactions between the …

Investigation Of Transport Behavior In Two-Dimensional Ferroelectric Heterostructures, Pradeep Chaudhary

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

This dissertation summarizes an investigation of the polarization-related electronic transport behavior in the ferroelectric thin films and two-dimensional (2D) materials heterostructures using Scanning Probe Microscopy (SPM) techniques.

The polarization-related resistive switching in hafnium oxide thin films-based ferroelectric tunnel junction has been demonstrated by employing semiconducting MoS₂ as a top electrode. We explored a coupling between the semiconducting properties of MoS₂ and the polarization of Hf₀.₅Zr₀.₅O₂ resulted in an enhanced tunneling electroresistance effect of up to 3 orders of magnitude. These results provide a possible pathway for the fabrication of …

Nanoscale Studies Of The Ferroelectric And Electromechanical Properties Of Hafnia-Based Capacitors, Pratyush Buragohain

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

The work presented in this dissertation aims to provide nanoscopic insights into the electrical and electromechanical behavior of the recently discovered ferroelectric HfO₂ or hafnia-based capacitors. Hafnia-based ferroelectrics are highly promising for technological applications due to compatibility with the existing Si technology. To realize the full potential of hafnia, however, requires comprehensive understanding of its properties. In this regard, this dissertation hopes to bridge a gap between an understanding of the nanoscopic and macroscopic properties of hafnia by performing combined high-resolution piezoresponse force microscopy (PFM) and pulse switching studies.

More specifically, the dynamics of domain nucleation and wall motion …

Causal Forest Approach For Site-Specific Input Management Via On-Farm Precision Experimentation, Shunkei Kakimoto

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

Estimating site-specific crop yield response to changes to input (e.g., seed, fertilizer) management is a critical step in making economically optimal site-specific input management recommendations. Past studies have attempted to estimate yield response functions using various Machine Learning (ML) methods, including the Random Forest (RF), Boosted Random Forest (BRF), and Convolutional Neural Network (CNN) methods. This study proposes use of the Causal Forest (CF) model, which is one of the emerging ML methods that comprise “Causal Machine Learning.” Unlike previous yield-prediction-oriented ML methods, CF focuses strictly on estimating heterogeneous treatment effects (changes in yields that result from changes in input …

Bridge Trisections And Classical Knotted Surface Theory, Jason Joseph, Jeffrey Meier, Maggie Miller, Miller Zupan

Department of Mathematics: Faculty Publications

We seek to connect ideas in the theory of bridge trisections with other wellstudied facets of classical knotted surface theory. First, we show how the normal Euler number can be computed from a tri-plane diagram, and we use this to give a trisection-theoretic proof of the Whitney–Massey theorem, which bounds the possible values of this number in terms of the Euler characteristic. Second, we describe in detail how to compute the fundamental group and related invariants from a tri-plane diagram, and we use this, together with an analysis of bridge trisections of ribbon surfaces, to produce an infinite family of …

Feature Analysis Of Indus Valley And Dravidian Language Scripts With Similarity Matrices, Sarat Sasank Barla, Sai Surya Sanjay Alamuru, Peter Revesz

School of Computing: Conference and Workshop Papers

This paper investigates the similarity between the Indus Valley script and the Kannada, Malayalam, Tamil, and Telugu scripts that are used to write Dravidian languages. The closeness of these scripts is determined by applying a feature analysis of each sign of these scripts and creating similarity matrices that describe the similarity of any pair of signs from two different scripts. The feature list that we use for the analysis of these Dravidian language-related scripts includes six new features beyond the thirteen features that were used for the study of Minoan Linear A and related scripts by Revesz. These new features …

Current Ecotoxicity Testing Needs Among Selected U.S. Federal Agencies, Patricia Ceger, Natalia Garcia-Reyero Vinas, David Allen, Elyssa Arnold, Raanan Bloom, Jennifer C. Brennan, Carol Clarke, Karen Eisenreich, Kellie Fay, Jonathan Hamm, Paula F.P. Henry, Katherine E. Horak, Wesley Hunter, Donna Judkins, Patrice Klein, Nicole Kleinstreuer, Kara Koehrn, Carlie A. Lalone, James P. Laurenson, Jessica K. Leet, Anna Lowit, Scott G. Lynn, Teresa Norberg-King, Edward J. Perkins, Elijah J. Petersen, Barnett A. Rattner, Catherine S. Sprankle, Thomas Steeger, Jim E. Warren, Sarah Winfield, Edward Odenkirchen

United States Department of Agriculture Wildlife Services: Staff Publications

U.S. regulatory and research agencies use ecotoxicity test data to assess the hazards associated with substances that may be released into the environment, including but not limited to industrial chemicals, pharmaceuticals, pesticides, food additives, and color additives. These data are used to conduct hazard assessments and evaluate potential risks to aquatic life (e.g., invertebrates, fish), birds, wildlife species, or the environment. To identify opportunities for regulatory uses of non-animal replacements for ecotoxicity tests, the needs and uses for data from tests utilizing animals must first be clarified. Accordingly, the objective of this review was to identify the ecotoxicity test data …

Defining An Epidemiological Landscape That Connects Movement Ecology To Pathogen Transmission And Pace-Of-Life, Kezia Manlove, Mark Wilber, Lauren White, Guillaume Bastille-Rousseau, Anni Yang, Marie L.J. Gilbertson, Meggan E. Craft, Paul C. Cross, George Wittemyer, Kim M. Pepin

United States Department of Agriculture Wildlife Services: Staff Publications

Pathogen transmission depends on host density, mobility and contact. These components emerge from host and pathogen movements that themselves arise through interactions with the surrounding environment. The environment, the emergent host and pathogen movements, and the subsequent patterns of density, mobility and contact form an ‘epidemiological landscape’ connecting the environment to specific locations where transmissions occur. Conventionally, the epidemiological landscape has been described in terms of the geographical coordinates where hosts or pathogens are located. We advocate for an alternative approach that relates those locations to attributes of the local environment. Environmental descriptions can strengthen epidemiological forecasts by allowing for …

Non-Nutritive Suck Burst Pattern Stability In Extremely Premature Infants, Alejandra Marquez

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

The development of non-nutritive suck (NNS) burst dynamics in preterm infants reflects the integrity of the brain and is used clinically to assess feeding readiness and orofacial motor development (Mizuno and Ueda, 2005). The application of NNS analytics in the present report represents one outcome measurement set that is part of an ongoing clinical trial involving extremely preterm infants (EPI’s,[GA]) randomized to receive either pulsed orocutaneous stimulation therapeutics or a sham (blind pacifier), in conjunction with salivary sampling twice weekly to map gene expression of key proteins involved in neural development and molecular sensing of feeding related pathways in the …

Using Remote And In Situ Observations From Torus To Investigate A Preexisting Airmass Boundary And Its Influence On A Tornadic Supercell On 28 May 2019, Kristen Axon

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

During the 2019 field phase of Targeted Observation by Radars and UAS of Supercells (TORUS), a preexisting airmass boundary was sampled on 28 May 2019 in north-central Kansas in close proximity to a tornadic supercell. This work hypothesized that the preexisting airmass boundary was associated with a mesoscale air mass with high theta-E (MAHTE) that favorably interacted with the tornadic supercell to increase the likelihood of tornadogenesis. Observations from TORUS including mobile mesonets, unoccupied aerial vehicles, soundings, and ground-based mobile radar were used along with GOES-16 visible satellite imagery, Kansas mesonet surface stations, and KUEX WSR-88D data to investigate this …

Majorana Bound States With Chiral Magnetic Textures, Utkan Güngördü, Alexey Kovalev

Department of Physics and Astronomy: Faculty Publications

The aim of this Tutorial is to give a pedagogical introduction into realizations of Majorana fermions, usually termed as Majorana bound states (MBSs), in condensed matter systems with magnetic textures. We begin by considering the Kitaev chain model of “spinless” fermions and show how two “half” fermions can appear at chain ends due to interactions. By considering this model and its two-dimensional generalization, we emphasize intricate relation between topological superconductivity and possible realizations of MBS. We further discuss how “spinless” fermions can be realized in more physical systems, e.g., by employing the spin-momentum locking. Next, we demonstrate how magnetic textures …

Majorana Bound States With Chiral Magnetic Textures, Utkan Güngördü, Alexey Kovalev

Alexey Kovalev Papers

The aim of this Tutorial is to give a pedagogical introduction into realizations of Majorana fermions, usually termed as Majorana bound states (MBSs), in condensed matter systems with magnetic textures. We begin by considering the Kitaev chain model of “spinless” fermions and show how two “half” fermions can appear at chain ends due to interactions. By considering this model and its two-dimensional generalization, we emphasize intricate relation between topological superconductivity and possible realizations of MBS. We further discuss how “spinless” fermions can be realized in more physical systems, e.g., by employing the spin-momentum locking. Next, we demonstrate how magnetic textures …

Deep Reinforcement Learning For End-To-End Network Slicing: Challenges And Solutions, Qiang Liu, Nakjung Choi, Tao Han

School of Computing: Faculty Publications

5G and beyond is expected to enable various emerging use cases with diverse performance requirements from vertical industries. To serve these use cases cost-effectively, network slicing plays a key role in dynamically creating virtual end-to-end networks according to specific resource demands. A network slice may have hundreds of configurable parameters over multiple technical domains that define the performance of the network slice, which makes it impossible to use traditional model-based solutions to orchestrate resources for network slices. In this article, we discuss how to design and deploy deep reinforcement learning (DRL), a model-free approach, to address the network slicing problem. …

Quantification And Machine Learning Based N2o–N And Co2–C Emissions Predictions From A Decomposing Rye Cover Crop, Deepak R. Joshi, David E. Clay, Sharon A. Clay, Janet Moriles-Miller, Aaron L. M. Daigh, Graig Reicks, Shaina Westhoff

Department of Agronomy and Horticulture: Faculty Publications

Cover crops improve soil health and reduce the risk of soil erosion. However, their impact on the carbon dioxide equivalence (CO_2e) is unknown. Therefore, the objective of this 2-yr study was to quantify the effect of cover crop-induced differences in soil moisture, temperature, organic C, and microorganisms on CO_2e, and to develop machine learning algorithms that predict daily N₂O–N and CO₂–C emissions. The prediction models tested were multiple linear regression, partial least square regression, support vector machine, random forest (RF), and artificial neural network. Models’ performance was accessed using R², …

Haemosporidian Parasite Diversity In An Under-Surveyed Australian Avifauna, Ian R. Hoppe, Allison E. Johnson, Elizabeth Vanwormer

School of Natural Resources: Faculty Publications

Haemosporidian parasites of birds are geographically widespread, have been detected in a phylogenetically diverse array of hosts, and have been the focus of extensive research due to both their impacts on birds and their similarity to vector-borne diseases of humans. Advances in molecular diagnostic tools have created a greater awareness of the genetic diversity of haemosporidian infections. Yet in spite of their more or less global distribution, comparatively little is known about the haemosporidians affecting birds in Australia. We screened blood from 889 birds (23 species) for haemosporidian blood parasite infections during the 2019 breeding season at Brookfield Conservation Park, …

Changes In Nonlinearity And Stability Of Streamflow Recession Characteristics Under Climate Warming In A Large Glaciated Basin Of The Tibetan Plateau, Jiarong Wang, Xi Chen, Man Gao, Qi Hu, Jintao Liu

School of Natural Resources: Faculty Publications

The accelerated climate warming in the Tibetan Plateau after 1997 has profound consequences in hydrology, geography, and social wellbeing. In hydrology, the change in streamflow as a result of changes in dynamic water storage that originated from glacier melt and permafrost thawing in the warming climate directly affects the available water resources for societies of the most populated nations in the world. In this study, annual streamflow recession characteristics are analyzed using daily climate and hydrological data during 1980–2015 in the Yarlung Zangbo River basin (YRB) of the southern Tibetan Plateau. The recession characteristics are examined in terms of dQ=dt …

Simulating Sub-Threshold Communication Channels Through Neurons, Richard Maina

School of Computing: Dissertations, Theses, and Student Research

Molecular Communication is an emerging paradigm with the potential to revolutionize the technology behind wearable and implantable devices and the broad range of functions they support, from tracking physical activity to medical diagnostics. This can be achieved through intra-body communication networks that take advantage of natural biological processes as a means of transmitting, propagating and receiving information. In this thesis we focus particularly on using the neuron as a means to facilitate information transfer for interconnected wearable or implantable devices through a technique known as sub-threshold electrical stimulation. We develop upon a prior work by introducing a linear model of …

The Diatom Dark Ages: Identification Of Mid-Cretaceous Arctic Platform Diatoms From The Basal Transgression Of The Kanguk Formation, Devon Island, Nunavut, Canada, Megan Heins

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

The lower part of the mid-Cretaceous Kanguk Formation (Lower Turonian interval) contains an important paleontological record crucial to the characterization of a poorly known interval of fossil marine diatoms history. Kanguk Formation mudstones are exposed in a ~200 m-thick section on Devon Island, Nunavut, Canadian High Arctic. Diatoms at this location are well-preserved due to shallow burial on this Arctic Platform site. The rock sequence was protected from glacial erosion that removed much of the Cretaceous record by being down-faulted in a linear graben. Study of these well-preserved fossil diatoms allows for a documentation of the assemblage, identification of potentially …