Digital Commons Network^™

A Stable-Isotope Probing Approach To Modeling Bidirectional Nutrient Exchange In The Microcystis Phycosphere, Malia Gardner

Masters Theses, 2020-current

Cyanobacterial harmful algal blooms (cHABs) plague freshwater systems worldwide and are projected to increase in intensity in the coming decades. cHABs damage aquatic ecosystems by blocking light penetration into the water column, creating hypoxic conditions, and releasing toxins. One of the most prolific cHAB formers is the cosmopolitan genus of cyanobacteria Microcystis. Global climate change and anthropogenic loading of nutrients such as nitrogen (N) and phosphorus (P) fuel Microcystis bloom formation. Increasing global temperatures favor Microcystis because of its high optimal growth temperature. N input is of particular importance for Microcystis because it is unable to fix atmospheric N, …

Effect Of Obesity On Walking To Running And Running To Walking Transitions, Salvador Baruch Alcorta Bautista

Theses and Dissertations

This work investigates human Walking to Running transition (WRT) and Running to Walking transition (RWT). The focus is to be able to identify the correct WRT and RWT phase jumps. This investigation uses experimental data from the VICON Motion Analysis System (MAS) and of the treadmill WRT and RWT trials. The musculoskeletal model consists of pelvis, femur, tibia, and foot. This investigation uses as reference the work reported in the literature by Diedricj and Warren.. For the calculations in this investigation Excel and Matlab are used to filter the data and calculate the relative phase jumps. This work reports the …

Biochar Applications To The Remediation Of Lead And Polychlorinated Biphenyl Contaminated Water, Victory Itua Igberase

Theses and Dissertations

This study investigated the performance of biochar materials as adsorbents to remove Pb and polychlorinated biphenyl (PCB) in aqueous solutions. Batch adsorption and column experiment packed with biochar and geomaterials (pumice) in 1:1 volume ratio was evaluated to address the efficacy of biochar in removing Pb while only batch adsorption was employed for PCB removal with biochar materials. Overall, PT biochars performed the best (42–53 mg g−1) followed by BE biochars (10–32 mg g−1) and AB biochars (17–27 mg g−1) while high temperature biochars were favored in terms of maximum Pb adsorption capacity. Column Pb breakthrough showed similar results, with …

I Buy Less When Others Suggest: Impact Of Personal Relative Deprivation, Temporal Discounting, Social Norms And Store Reputation On Food Over-Acquisition, Swapnil Saravade

Theses and Dissertations

Food over-acquisition has shown to have detrimental consequences such as food over-consumption, food waste, obesity, and greenhouse effects. Extant literature has typically focused on food over-consumption, with little explanation of its precursor, food over-acquisition. The current thesis situates the research in grocery retail and examines why people over-acquire food. Further, which interventions can marketers develop to mitigate food over-acquisition and in which grocery stores would those be effective? The present dissertation approaches this issue by drawing concepts from two disciplines, sociology, and behavioral economics. Through five studies, the current thesis shows that when people feel relatively food-deprived, they tend to …

Soil Chemistry Modification By Guinea Grass In Semi-Arid Soils: A Litter Mediated Positive Feedback, Vanessa Elizabeth Thomas

Theses and Dissertations

Nutrients are a key component of healthy soils. Their composition plays an important role in plant growth through nutrient cycling and directly influences the functioning of plant communities in both agricultural and natural ecosystems. Shifts in macronutrients such as phosphorus and nitrogen may be initiated by invasive growth as a driver for competition with native plants. The goal of this study is to explore the plant soil feedback in an exotic invasive plant, Guinea grass (Pancium maximum), an invasive bunch grass originally from Africa, across different habitat types in the Lower Rio Grande Valley (LRGV). To determine a positive plant …

Star Wars: The Clone Wars And Popular Culture In America, Ubaldo Zermeno

War, Diplomacy, and Society (MA) Theses

The Clone Wars animated series is part of the Star Wars storyline taking place before the original Star Wars: Episode IV - A New Hope. The central premise of The Clone Wars is that of war, one being waged by a biologically manufactured clone army. George Lucas’ intent for the original Star Wars was to create a social dialogue reflecting the ideological reasons for, and effects of, the Vietnam War. The Clone Wars continues Lucas’s examination of American wartime policies and their effects on society.

The themes in The Clone Wars are diverse; however, this analysis will cover the …

Determination Of The Optimal Parameters For Self-Healing Efficiency Of Encapsulated Bacteria In Concrete Simulated Subtropical Climate, Momen R. Mousa, Marwa Hassan, Gabriel Andres Arce Amador, Ricardo Hungria, Andrea Gavilanes, Omar Kamal

Publications

Concrete is a remarkable construction material. However, its low tensile strength makes it prone to cracking, which negatively affects its durability. To address this issue, bacterial concrete has been implemented as a self-healing alternative due to its capability to seal microcracks through microbial-induced calcium carbonate precipitation (MICCP). In this study, a bacterial strain (i.e, Bacillus Pseudiformus) was encapsulated through three different methods: encapsulation through hydrogel beads, vacuum impregnation on lightweight aggregates, and attachment to cellulose nanocrystals. Furthermore, three precursor types were used, magnesium acetate, calcium lactate, and sodium lactate were implemented. Compressive strength tests and flexural strength tests were performed …

Alfred Russel Wallace Notes 18: Wallace On The Balance Of Nature, Charles H. Smith

Faculty/Staff Personal Papers

Alfred Russel Wallace (1823−1913) had a unique perspective on the ‘balance of nature’: he avoided classical thoughts on the subject, but nevertheless seems to have adopted elements of the ‘balance’ concept while acknowledging that irreversible change occurs at both the biological and environmental levels. Wallace’s position can be understood from his grounding in Humboldtian ‘equilibrium of forces’ thinking, and his turn toward ‘final causes’-based interpretations.

Church Deemed A “Hate Group” By Southern Poverty Law Center Loses Its Battle With Amazon.Com Over Exclusion From The Amazonsmile Program, Arthur S. Leonard

Other Publications

No abstract provided.

Characterization Of Sabp2-Interacting Proteins (Sip) 428: An Nad+-Dependent Deacetylase Enzyme In Plant Abiotic Stress Signaling, Oviavo Nohoesu

Electronic Theses and Dissertations

Abiotic stress leads to a change in the water content of plants. Salinity and osmotic stress affect both the morphology and physiology of plants. Plants have therefore responded to these environmental changes by adapting and tolerating them. The SABP2-interacting proteins (SIP) 428-silenced RNAi transgenic tobacco lines were subjected to various abiotic stresses (salinity, osmotic, and drought). The effect of SIP428-silencing on the tobacco plants subjected to these abiotic stresses was monitored. The results from the root growth data show that the sip428-silenced lines exhibit enhanced tolerance to the stressors compared to the wild-type plants. Interestingly, results of the relative chlorophyll …

Faculty Research Profile: Bin Dong, Lutishoor Salisbury, Yang Tian, Jeremy Smith

University Libraries Faculty Publications and Presentations

This poster was compiled to commemorate the hiring of Dr. Bin Dong as Assistant Professor to the Department of the Chemistry and Biochemistry at the University of Arkansas from August 2021. It provides a summary of his research achievements and scholarly impact.

The Impact Of Out-Of-Home Placements On Juvenile Delinquency And The Protective Factors That Neutralize Offending, Kenneth James Kilian

Doctoral Dissertations and Projects

The negative effects of adverse childhood experiences have been widely examined; however, there has been limited research exploring the association between out-of-home placements and juvenile delinquency. Evidence suggests that positive bonding and associations mitigate maladaptive behaviors, yet it remains unclear if certain protective factors have an equally mediating effect on offending. The current study expanded on the existing criminological literature of juvenile offending by applying general strain theory and developmental taxonomy as the frameworks for the association between childhood traumas, protective factors, and juvenile offending. Data were drawn from the Pathways to Desistance Study using foster care, residential treatment centers, …

Incorporating Machine Learning Algorithm In Modified Quality By Design Approach On Simulated Penicillin Fermentation Dataset, Shengting Xu

Dissertations and Theses (Open Access)

For this thesis, we utilized random forest (RF) algorithm in combination with Quality by Design (QbD) in simulated commercial-scale penicillin production dataset. The RF algorithm was primarily used in the selection of critical process parameters (CPPs). In this analysis, the primary critical quality attributes (CQA) was set to be the final penicillin yield. After the CPPs were selected by the RF algorithm, we would propose design of experiment (DoE) by using fractional factorial design to establish mathematical relationships between CPPs and CQAs. Among the five RF models, we chose two models before proceeding to the DoE step. One using the …

Fast Magnetic Resonance Image Reconstruction With Deep Learning Using An Efficientnet Encoder, Tahsin Rahman

Open Access Theses & Dissertations

This thesis aims to develop an efficient, deep network based method for Magnetic Resonance Imaging (MRI) acceleration through undersampled MR image reconstruction. Deep Neural Networks, particularly Deep Convolutional Networks, have been demonstrated to be highly effective in a wide variety of computer vision tasks, including MRI reconstruction. However, modern highly efficient encoder structures, such as the EfficientNet can potentially reduce reconstruction times further while improving reconstruction quality. To that end, we have developed a multi-channel U-Net MRI reconstruction network which uses an EfficientNet encoder and a custom asymmetric. The network was trained and tested using 5x undersampled multi-channel brain MR …

Towards Reinforcement Learning Driven Mesh Adaptivity For Second Order Elliptic Problems, Augustine Twumasi

Open Access Theses & Dissertations

Adaptive mesh refinement techniques have become an indispensable tool in achieving accurate and efficiently computed solutions to problems which require impractically fine uniform meshes to obtain an accurate approximation. The adaptive algorithm involves a recursive application of SOLVE-ESTIMATE-MARK-REFINE steps where in particular the step `ESTIMATE' involves computing a posteriori error estimator based on only the numerical solution and the data of the problem. Over the years, several a posteriori error estimators have been developed and successfully applied but often times, the choice of estimator is ill suited for the problem at hand. In this research, we present two estimators namely …

Analyzing Genetic Variation Of The Tussock Cottongrass Among Ecotypes Along A Latitudinal Gradient Through Transcriptomics, Carmen Webster

Open Access Theses & Dissertations

The Arctic is seeing some of the most extreme effects of climate change that induce environmental pressures, including warmer temperatures and longer growing seasons. Due to this, taxa may need to adapt or migrate in order to survive. The long-lived tussock cottongrass, Eriophorum vaginatum, is a foundation species in the Arctic, and little is currently known about the genetic constraints that could be playing a role in how this species will respond to the changing climate. Specific gene families that play an important role in signaling genetic pathways related to plant phenology and response to environmental stress are likely to …

Restoring Biogeochemical Properties In Drylands And Exploring Functional Roles Of Biological Soil Crust, Kristina Young

Open Access Theses & Dissertations

Degradation in dryland regions is a persistent and accelerating problem. Though the mechanisms that initiate and maintain dryland degradation have been well studied, restoring productivity and function to degraded dryland ecosystems remains difficult. Here, I present three chapters that address gaps in our understanding of dryland functions and our ability to restore them. I begin by examining how dryland restoration research has addressed altered biogeochemical cycling in drylands and how to expand current understandings of dryland biogeochemistry into restoration. I then present two chapters that explore mechanistic and quantitative understandings of the contribution of biocrusts to soil nutrient cycling both …

The Influence Of Emotion Regulation, Maladaptive Coping, And Criminal Thinking On Maladaptive Behavior, Alondra Avila

Open Access Theses & Dissertations

Emotion regulation is a cognitive process that occurs due to emotional stimuli in the environment that promotes cognitive or behavioral action to soothe negative emotions. Emotion regulation can affect decision making that promotes maladaptive behavior, similar to criminal thinking. Criminal thinking patterns can be categorized as a form of maladaptive cognitive coping that promotes maladaptive behavior. The association between emotion regulation, criminal thinking, and maladaptive behavior is further explored. A total of (N = 227) MTurk workers participated in a cross-sectional study. Maladaptive emotion regulation and coping predicted willingness to engage in maladaptive behavior. Deficits in emotion regulation were further …

Development Of A Laser Solder Process For Use With Material Extrusion Additive Manufacturing And Rapid Electronics Prototyping In Embedded Sensing Applications, Emerson Roland Armendariz

Open Access Theses & Dissertations

Industrial and rapid prototyping (RP) trends toward miniaturization of electronic devices containing temperature sensitive electronics and surrounding materials are calling for highly controllable, selective laser soldering technologies. Laser soldering is a non-contact technique that eliminates the risk of marring or damaging sensitive components by precisely focusing a laser beam on a solder filler alloy, leading to a fast and non-destructive electrical joint. Using the benefits of accurate and controlled heat delivery via inexpensive low power laser diodes (LPDL's) in conjunction with ever-increasing additive manufacturing capability in producing complex internal features and geometries, development and testing of a laser application system …

In The Search For Novel Treatments For Chagas' Disease Using Cutting-Edge Imaging Technology, Karsten Dieter Amezcua Winter

Open Access Theses & Dissertations

Chagas disease (ChD) is caused by Trypanosoma cruzi (T. cruzi), an intracellular protozoan parasite. ChD has a global mortality of 15,000 annual deaths, and approximately, 8-10 million people are infected. There is growing concern in the United States as autochthonous cases of ChD have been reported in the southern region. The two available treatments are only partially effective and highly toxic. N-aroyl derivatives and α, β-unsaturated ketones have been previously tested against Leishmania, a closely related parasite, demonstrating selective toxicity towards the microorganism. The objective of this study is to evaluate a drug library consisting of 21 α, β-unsaturated ketones …

Landscape Population And Evolutionary Genomics Of Several Closely Related Species Of Mallard-Like Ducks, Joshua Brown

Open Access Theses & Dissertations

Divergence and speciation proceed through three major evolutionary forces (i.e., selection, genetic drift, and gene flow) that are often spatially and temporally heterogeneous across the landscape. Moreover, these forces can have differing but subtle effects within the genomes of diverging taxa, and therefore, disentangling the effects of these evolutionary mechanisms throughout the speciation process can be challenging. Here, I use a recent species radiation, the mallard complex, to investigate how strong, yet varied, evolutionary pressures influence the speciation process. The mallard complex consists of 14 mallard-like waterfowl species around the world that have some of the highest rates of hybridization …

Molecular Dynamics Of Nucleic Acids, Proteins, And Their Complexes: From Atomistic And Coarse-Grained Descriptions To New Methodologies, Parth Chaturvedi

Open Access Theses & Dissertations

Computational modeling of biological macromolecules through molecular dynamics (MD) simulations is becoming increasingly useful to interpret the experimental results and guide the future experiments. Over the last decade, MD simulations have become much more powerful and accessible due to advancements in fields of structural biology, computer science and integrated chip design. In this Thesis, I utilize different MD simulation techniques to model interaction of and antiviral mechanisms. Within the framework of nucleic acid modelling, we describe first dynamics of small circular single stranded nucleic acids and highlight key dynamical differences of backbone behavior in solution between DNA and RNA and …

Articulating The Importance Of Broader Relevance In Cures: From Definition To Actualization, Nikki T. Donegan

Open Access Theses & Dissertations

Course-based undergraduate research experiences (CUREs) have emerged as a means to foster student' scientific reasoning, promote positive attitudes and motivations toward research, and increase persistence in the science, technology, engineering, and mathematics (STEM) fields. In contrast to prescriptive laboratories, students enrolled in CUREs employ techniques and skills to collaboratively and iteratively address novel questions of broad relevance to audiences beyond the scope of the course itself. While many of the core components of CUREs are perceived to be relatively straightforward, definitionally-speaking, this latter dimension of broader relevance has, in contrast, remained largely ill-defined. In the series of studies presented herein, …

Structural Microheterogeneity In Ionic Liquid/Solvent Mixtures Influenced By Solvent Polarity And Ion Concentration, Babatunde Falola

Open Access Theses & Dissertations

Room temperature ionic liquid (RTIL) and organic solvent mixtures, in supercapacitors, have desirable properties in comparison to conventional electrolytes. We studied the nanostructural properties of mixtures of the RTIL: 1-butyl-3-methylimidazolium bis (trifluoromethyl sulfonyl) imide (abbreviated to BMIM+[TSI]-), with organic solvents: acetonitrile, dichloromethane, benzene, toluene, and tetrahydrofuran. The mass percentage at which macroscopic phase separation is visible in each RTIL and solvent mixture was determined by slowly increasing the solvent concentration. Small-angle x-ray scattering (SAXS) measurements, at RTIL mass percentage lower than the phase separation concentrations, were carried out to determine whether nanoheterogeneity is presently leading up to macroscopic phase separation. …

Associations Between Exposure To Air Pollution After A Dust Event And Hospitalizations., Estrella De Jesus Herrera-Molina

Open Access Theses & Dissertations

The Southwestern region has been identified as one of the most persistent dust producing regions of North America. Exposure to inhalable particulate matter (PM10) originating from desertic landscape during dust events/dust exposures (DEs) can reach hazardous levels. El Paso, Texas’s ambient air has reached hazardous levels of PM10 above 4000 μg/m3 with near zero visibility due to these natural events. There are very few prior studies in the southwestern United States pertaining to the associations between exposure to atmospheric aerosol after DEs and hospitalizations, nor are there many epidemiological studies globally in dusty environments where most of the atmospheric aerosol …

Evaluation Of Electrodialysis Desalination Performance Of Novel And Conventional Ion Exchange Membranes, Ahm Golam Hyder

Open Access Theses & Dissertations

It was revealed from relevant recent literature that the electrodialysis (ED) desalination performance of commercial and laboratory-made ion exchange membranes (IEMs) had been studied previously but not in a systematic way so that the planners, designers, and engineers can evaluate a trade-off in selecting the suitable IEMs and optimum ED experimental conditions for their desired outcomes such as high ion selectivity, high salinity removal, high water recovery, low energy consumption, or low water transport. Furthermore, the existing conventional and laboratory-made IEMs reported previously showed various technical and economical limitations with respect to permeability, permselectivity, ion selectivity, electrical resistance, stability (mechanical, …

Interaction Of Kinesin-5 Motor Domain With Tubulin Dimer, Chitra B. Karki

Open Access Theses & Dissertations

Kinesin-5 in fission yeast also known as Cut7 is a molecular motor essential for separation of spindle fibers during the mitotic cell division. Kinesin-5 crosslinks the spindle microtubules and slides them towards the spindle poles. Molecular dynamics simulation was performed, and various analysis were carried out to study the interaction of kinesin-5 motor domain with alpha and beta tubulins. From electrostatic potential distribution, it is observed that binding interface of kinesin-5 motor domain is mainly positive and tubulin dimer is mainly negative, which shows the stronger interaction between them. Further when electric field lines were plotted, we observed more field …

Surveillance Of Ticks And Associated Pathogens In Central Texas, Alexa Mendoza

Open Access Theses & Dissertations

Background: Ticks are the second most common vector of human and veterinary pathogens, after mosquitoes, which results in a number of different diseases around the world. These diseases, referred to as tick-borne diseases (TBDs), are increasing in their prevalence around the world as the geographical distribution of ticks change due to environmental and human factors. Increased testing for pathogens and a better comprehension of their relationship to different tick species will be crucial in deepening our understanding of TBDs and protecting our human and animal populations. Increasing surveillance of ticks and the potential pathogens they may be vectors for and …

Studies Of The Planetary Boundary Layer And Their Impact On Air Pollution In A Semi-Arid Region With Complex Terrain, Nakul Nitin Karle

Open Access Theses & Dissertations

The adjacent cities of El Paso-Juárez, located in the Rio Grande Rift Valley and surrounded by complex mountainous terrain, have undergone rapid urbanization and industrial growth in the last few decades, accompanied by increasing substandard air quality episodes. Although numerous air quality studies were conducted in this semi-arid region in the past, none focused extensively on the Planetary Boundary Layer (PBL) contribution and impact on air pollutant concentrations. In this work, both the high and low ozone episodes from 2015 to 2020 were examined. Both modeling and experimental data of the PBL height (PBLH) were obtained and related to atmospheric …

The Role Of Calcium Ions In Signaling And Regulation Of Efflux Pump Genes In Staphylococcus Aureus, Amy Rebecca Nava

Open Access Theses & Dissertations

Calcium ions (Ca2+) play an important role in eukaryote cell signaling and regulation of physiological functions. Although evidence of a similar role for Ca2+ in prokaryotes has been difficult to demonstrate, there is mounting evidence that Ca2+ acts as a cell regulator in bacteria. The purpose of this study was to investigate Ca2+ signaling and the effect of Ca2+ on gene expression of various multidrug resistant (MDR) efflux pumps and their regulator MgrA in Staphylococcus aureus and clinically isolated MRSA. We hypothesized that the presence of Ca2+ increased gene expression of multidrug resistance pumps, LmrS, NorA, and the regulator, MgrA. …