Digital Commons Network^™

Palmer Amaranth [Amaranthus Palmeri (S.) Wats.] Resistance To S-Metolachlor In The Mid-Southern Us And S-Metolachlor Dissipation In Soil, Koffi Badou Jeremie Kouame

Graduate Theses and Dissertations

Palmer amaranth [Amaranthus palmeri (S.) Wats.] presents both a high genetic diversity and propensity to evolve resistance to herbicides of several sites-of-action which have made it one of the worst weeds in US agriculture. In Arkansas, Palmer amaranth is resistant to herbicides of seven sites-of-action, which are 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) inhibitor, acetolactate synthase inhibitors, microtubule inhibitors, protoporphyrinogen oxidase inhibitors, very long chain fatty acid inhibitors, glutamine synthetase inhibitors, and hydroxyphenylpyruvate dioxygenase inhibitors. Sustainable management requires a better understanding of its biology and that of herbicide environmental fate. This research had five objectives: 1) characterize the current status of Palmer amaranth …

Sigesn Light-Emitting Devices: From Optical To Electrical Injection, Yiyin Zhou

Graduate Theses and Dissertations

Si photonics is a fast-developing technology that impacts many applications such as data centers, 5G, Lidar, and biological/chemical sensing. One of the merits of Si photonics is to integrate electronic and photonic components on a single chip to form a complex functional system that features compact, low-cost, high-performance, and reliability. Among all building blocks, the monolithic integration of lasers on Si encountered substantial challenges. Si and Ge, conventional epitaxial material on Si, are incompetent for light emission due to the indirect bandgap. The current solution compromises the hybrid integration of III-V lasers, which requires growing on separate smaller size substrates …

Synthesis Of Polyethylene Glycol-Based Hydrogels And Silver/Gold Nanostructures For Biomedical Applications, Isabelle Ishimwe Niyonshuti

Graduate Theses and Dissertations

This work focuses on the synthesis of biocompatible polyethylene glycol (PEG)-based hydrogels, silver nanoparticles (AgNPs), and silver-gold nanocages (Ag-AuNCs) for biomedical applications. The dissertation includes two parts with Part I on the work of PEG-based hydrogel for wound healing applications and Part II on the work of Ag/Au nanostructures for antimicrobial applications. Part I studies PEG-based hydrogel for the delivery of fibroblast growth factors (FGFs) for wound healing applications, aiming to overcome the challenge of designing hydrogels capable of the sustained release of bioactive FGFs. This research develops new biocompatible anionic injectable hydrogel formulations based on Poly (Oligo Ethylene Glycol …

Does Whispering Improve Children’S Memory? Comparing Auditory Vigilance And Salience Hypotheses, Christina M. Barnes

Graduate Theses and Dissertations

Oral communication is one of the primary tools children use to learn new information and speech registers can deliver additional meaning to the words someone uses. Cirillo’s (2004) vigilance hypothesis states “Whispering can affect the psychobiological state of recipients, and in particular raise their auditory vigilance” (Cirillo, 2004, p. 76). Building on this theory, the current study investigates the role of whispering and children’s memory by examining a whispering vigilance, whispering salience which focused on the changes between normal and whisper registers, and combined vigilance and salience hypotheses to determine if whispering contributes to the recall of information. Using video …

Forced And Unforced Permafrost Changes In The Northern Hemisphere During 1901-2100, Hong Guo

Graduate Theses and Dissertations

Permafrost regions are very sensitive to rapid changes in climate and environment. In recent decades, there has been growing interest to better understand the permafrost degradation over the Northern Hemisphere in the context of human-induced climate change. Understanding permafrost dynamics is not only important for infrastructure but also for environmental protection in cold regions. In-situ permafrost measurements are important for assessing permafrost conditions. However, direct permafrost observations are sparse and asymmetrical in both spatial and temporal coverage. Active layer thickness (ALT) modeling is another approach that can overcome many of these limitations, but the models have large uncertainty in predicting …

Hybrid Two Dimensional Quantum Devices, Joshua Patrick Thompson

Graduate Theses and Dissertations

This thesis describes measurements on hybrid material systems involving two dimensional (2D) materials and phenomena along with the development of a small, hermetically sealed cell. The hermetic cell is designed to assist with analyzing sensitive 2D materials outside of an inert environment. When working with van der Waals materials that are especially sensitive to oxygen or water, it can be difficult to identify usable thin flakes without exposing them to air. To help preserve materials for analysis in air, a capsule was designed that isolates the material in an inert environment. Although the capsule is hermetically sealed, the encapsulated material …

The Effects Of Commercial Harvest On The Density And Demography Of Aquatic Turtles In Arkansas, Andrhea Darleen Massey

Graduate Theses and Dissertations

The United States is home to the second highest concentration of turtle species in the world, after Asia. As of 2018, there are 57 turtle species recognized within the US, 40% of which are listed as threatened or endangered, with the primary threats to population persistence identified as over-consumption and/or habitat loss. Within the US, the Mississippi Alluvial Valley (MAV) region represents the second highest turtle species richness, after the Mobile River Basin. The MAV region of Arkansas is one of the least regulated in terms of commercial aquatic turtle harvest and has undergone large-scale habitat conversion from bottomland hardwood …

Longitudinal Monitoring Of Tumor Response To Immune Checkpoint Inhibitors Using Diffuse Optical Spectroscopy, Joel Isaac Rodriguez Troncoso

Graduate Theses and Dissertations

Immune checkpoint drugs have completely changed the way people treat metastatic melanoma and non-small-cell lung cancer. While the impacts of these immunological checkpoints and their suppression on T cell function are well characterized, their consequences on the tumor microenvironment are not. In a CT26 mouse colorectal cancer model, we employed diffuse reflectance spectroscopy to track in vivo tumor microenvironmental alterations in response to immune checkpoint inhibitors. On three separate days, animals bearing CT26 tumor xenografts were given anti-PD-L1, anti-CTLA-4, a combination of both inhibitors, and isotype control. Within the first 6 days, monotherapy with either anti-PD-L1 or anti-CTLA-4 resulted in …

In The Line Of Duty - A Documentary Film About Davis Duty And His Seeing Eye Dog, Paulina Sobczak

Graduate Theses and Dissertations

“In the Line of Duty” is a documentary film about Jeff Davis Duty, a man from a small town in Arkansas, who lost his sight at the age of five. He is the oldest Seeing Eye dog user in the world. At the age of 22, he was awarded a Fulbright Scholarship at the London School of Economics in England, as the first Fulbright Scholar with disability. Duty achieved great success in his career as a lawyer, leading a fulfilling and enjoyable life. The documentary film’s storytelling focuses on Duty’s life from his childhood to current times and presents all …

Development Of Aptamer Rolling Circle Amplification Platform As A Vaccine Adjuvant To Control Salmonella In Broiler Chickens, Abigeal Iyabode Omolewu

Graduate Theses and Dissertations

Salmonella has been a major source of concern in public health and food industry. It is the cause of gastrointestinal illness and fever called salmonellosis. Severe cases of salmonellosis have resulted in hospitalization and even death around the world. Salmonella can be found in the intestinal tract of animals including chickens and can be transmitted to human through contaminated food. Hence, it is highly important to find ways of reducing the transmission of Salmonella from chickens to humans. This work is focused on the control of Salmonella in broiler chicken through the development of novel vaccine adjuvant. Two different aptamer …

The Same River Twice, Claire Remy Pincumbe

Graduate Theses and Dissertations

This thesis is a portion of a novel written during my time at the University of Arkansas.

Body Mass And Body Condition Variation Of Mallards (Anas Platyrhynchos) Within And Among Winters Within The Lower Mississippi Alluvial Valley, John Thompson Veon

Graduate Theses and Dissertations

Most North American waterfowl overwinter in southern North America before migrating back to breeding grounds in the northern US and Canada. These species face the challenge of needing to maintain or increase their body mass during an environmentally difficult winter period. Successful body mass maintenance during the winter period has major ramifications not only for their winter survival but for their fitness across the entire year. Recent research in Europe and the western United States suggests that the body mass of mallards (Anas platyrhynchos) has increased from the late 1960s to early 2000s. However, the factors responsible for increases in …

Just Benjamin, Paige R. Murphy

Graduate Theses and Dissertations

This documentary short film is about a now 30-year-old transgender man telling his story of growing up queer in a small Arkansas town, from being outed as a lesbian in high school, to ultimately being accepted as a trans man by members of his military and biological families. Benjamin “Benji” Davis grew up in the small town of Friendship, Arkansas, enlisted in the U.S. Army shortly after high school and served for six years, then came back to Arkansas and primarily lived in Little Rock until he moved to Denver, Colorado this fall. The documentary is structured linearly both with …

A Case Study Of Eastern Region Arkansas Promise Participants And Their Expectations For The Future, Robin Freeman

Graduate Theses and Dissertations

The purpose of this study was to develop an in-depth understanding of how Eastern Arkansas youth with disabilities and their parents describe their expectations for the future, after participating in the Arkansas PROMISE program. The study sought an understanding of how participants viewed themselves and their expectations for the future, for employment, for participation in higher education, for independent living, and for future financial support. The research used a case study approach, interviewing five students and five parent participants. Participants were asked a series of questions to get an understanding of their experiences, their expectations for the future, and their …

Two-Dimensional Black Phosphorus For Terahertz Emission And Near-Field Radiative Heat Transfer, Mahmudul Hasan Doha

Graduate Theses and Dissertations

The main focus of this work is to investigate two potential optical and optoelectronic applications of black phosphorus (BP): the near-field radiative heat transfer in plasmonic heterostructures with graphene and terahertz emission from multi-layer BP photoconductive antennas. When the separation distance between graphene-black phosphorene is much smaller than or comparable to the thermal wavelength at different temperatures, a near-field radiation heat transfer breaks the Planck blackbody limit. The magnitude of the near-field radiation enhancement acutely depends on the gate voltage, doping, and vacuum gap of the graphene and BP pair. The strong near-field radiation heat transfer enhancement of the specific …

Site-Specific Effects Of Lysine Acetylation On Aminoacyl-Trna Synthetase, Hao Chen

Graduate Theses and Dissertations

Aminoacyl-tRNA synthetases (AARSs) are an ancient and highly conserved family of enzymes which can catalyze a two-steps aminoacylation reaction to charge tRNAs with their cognate amino acids, thus playing crucial roles in ribosomal protein synthesis. Naturally, the accurate amino acids and tRNA recognition of these synthetases are essential to the fidelity of translation process. To assure the correct recognition, some of these synthetases have evolved with an editing function to help remove the mischarged tRNAs. In addition to these functions, AARSs are also involved in various biological processes ranging from transcription to translation. Currently, a series of proteomic studies have …

Remixed, Remastered: Investigating Organizational Adaptation In Higher Music Education, Jacob Bruce Hertzog

Graduate Theses and Dissertations

Higher music education presents a unique opportunity to examine change within higher education due to the digital revolution in the music industry over the past two decades. The purpose for conducting this study was to describe, map, and explain the strategies that higher music education programs are using to adapt to the digital revolution in the music industry. This study was grounded in organizational adaptation theory, drawing upon nine well-established theories: population ecology, life cycles, strategic choice, isomorphism, symbolic action, resource dependence, cybernetics, and network theory. Critical concepts of the turbulent environment, environmental perception, and organizational adaptation strategy emerged from …

Lgbtq+ College Students' Perceptions Of Social Presence And Self-Disclosure In Online Learning: A Single-Case Study, Scott Anthony Wright

Graduate Theses and Dissertations

Social interaction among learners plays a significant role in online learning environments (Garrison, 2006; Kreijns et al., 2014; Mykota, 2017). The construct of social presence in online courses is important because it influences interaction and connectedness among learners and its effects on their learning outcomes and emotional well-being. Social presence at its essence refers to how an individual is perceived as a "real person" in an online environment (Gunawardena & Zittle, 1997). Online students must decide what aspects of their social identities they share in their interactions with their peers and instructors. Furthermore, LGBTQ+ students must negotiate what aspects of …

Analysis Of Bacteriorhodopsin Suspended In A Bilayer Lipid Membrane, Moath Alhejji

Graduate Theses and Dissertations

The bacteriorhodopsin protein’s unique characteristic of proton pumping can convert light energy to electric energy. The aim of this research was to generate photocurrent using bacteriorhodopsin in a bi-layer lipid membrane. Lipid monolayer and bilayer were formed using painting and folding methods, respectively. Capacitance and resistance of the lipid membranes were measured and used to validate the best methodology. My results show that the folding method is more efficient in incorporating Bacteriorhodopsin. The photocurrent was generated by illuminating a green laser (532 nm) on the bilayer lipid membranes. The patch clamp electrophysiology technique was used to apply voltage across the …

Reducing Dietary Crude Protein: Characterization Of Branched-Chain Amino Acid Antagonism In Modern Broiler Chickens, Craig William Maynard

Graduate Theses and Dissertations

Reducing the crude protein content of broiler diets while maintaining performance has been a primary research area in nutrition. During the late 20th century, the bulk of this research has involved supplementing broiler diets with feed-grade amino acids and proving the economic benefits of their additions. To date, widespread adoption of feed-grade amino acids is limited to methionine, lysine, threonine, and to some extent valine. With valine and isoleucine gaining prevalence in commercial formulation, classic data on the antagonisms associated with the branched-chain amino acids has returned to the forefront of practical broiler nutrition research. Therefore, a series of 23 …

Automated Flight Controller Adaptive Compensation For Actuator Failures In Transport Type Aircraft, Daniel James Fresella

Graduate Theses and Dissertations

Aircraft operate over a wide range of conditions including atmospheric, weight, and center ofgravity changes. This presents a substantial challenge to automatic control system designers. When these operating conditions are merged with a partial or full control surface failure, automatic flight control is near impossible with conventional controllers. Additionally, when pilots experience control failure emergencies during flight, workload and fatigue increase drastically. The continued research of automatic flight control systems that can seamlessly adapt to unmodelled failures will enable a new generation of robust aircraft control. In this paper a 9th order 6 degree of freedom aircraft model is used …

Fair And Diverse Group Formation Based On Multidimensional Features, Mohammed Saad A Alqahtani

Graduate Theses and Dissertations

The goal of group formation is to build a team to accomplish a specific task. Algorithms are being developed to improve the team's effectiveness so formed and the efficiency of the group selection process. However, there is concern that team formation algorithms could be biased against minorities due to the algorithms themselves or the data on which they are trained. Hence, it is essential to build fair team formation systems that incorporate demographic information into the process of building the group. Although there has been extensive work on modeling individuals’ expertise for expert recommendation and/or team formation, there has been …

Catalytic Activity Of Molybdenum-Dioxo Complexes, Randy Tran

Graduate Theses and Dissertations

This dissertation details the development of rationally designed dioxomolybdenum catalyst active for deoxydehydration (DODH), the net reduction of diols and polyols into alkenes and dienes. Catalyst design involved variations on dioxomolybdenum(VI) supported by a dianionic meridional pincer ligand. Rational substrate scope was explored using aliphatic diols, aromatic diols, and biomass derived diols. Various reductants were tested for ability to catalyze the reaction. The substrate specific mechanism of DODH was explored utilizing NMR and in-situ infrared spectroscopy and important rate constants and rate determining steps were found to aid in the optimization of ideal reaction conditions. Catalytic activity was observed to …

A Song Of The Bluff: The Phoenix Of Pine Bluff Arkansas - Documentary, Neba Evans

Graduate Theses and Dissertations

Pine Bluff, Arkansas has long grappled with a reputation as a town riddled with crime and violence. Once a thriving agricultural center of the state, Arkansas residents tend to score the town’s successes as relics of the past. Economic decline, negative migration systems like white flight and brain drain, and racial disparities ties to the city’s roots has continued to take its toll on the city. Nonetheless, the community of Pine Bluff knows excellence has and continues to prosper there. A Song of the Bluff is a 15-minute documentary that seeks to flip the negative narrative by confronting these stereotypes …

Sensitivity Of Soybean And Rice To Dicamba, Owen Wesley France

Graduate Theses and Dissertations

Although the integration of dicamba as a postemergence (POST) herbicide has proven useful in controlling many herbicide-resistant weeds, its damage to soybean at low rates, such as supplied by drift and volatility, has been well-documented. Injury to other crops, such as rice, from off-target movement of dicamba and other commonly used herbicides, such as glyphosate, may also occur. Practical options for mitigating injury and yield loss to soybean and other crops from dicamba off-target movement could prove beneficial if dicamba continues to be used during summer months. Experiments were conducted to determine the effects of multiple agricultural practices, including cultivar …

Adapting Animals: Nineteenth-Century British Literature, Science, And Media, Kristen Layne Figgins

Graduate Theses and Dissertations

In the nineteenth century, Charles Darwin and other proponents of evolutionary theory provided a theoretical framework for discussing the question of humanity’s place in the world. These nascent theories emphasized the shared animal nature of humans and the nonhuman creatures who had once occupied a distinctly lower place on the chain of being. My dissertation addresses the question of how nineteenth-century scientific attitudes about animals were reflected in the literature of the period. By examining culture-texts from the nineteenth century, it is clear that literature was an active participant in extending scientific knowledge, often by playing with the blending categorical …

Nocturnal Pollination In Fruit Agriculture, Stephen Robertson

Graduate Theses and Dissertations

Insect pollination in agriculture provides as much as 35% of the global food supply and contributes hundreds of billions of dollars to the global economy each year. In the past 30 years, reports of declining populations of managed and wild bees, notably the western honey bee (Apis mellifera) and a wide array of bumble bees (Bombus spp.), have raised concerns about the stability and outlook of agriculture. At the same time, agricultural dependence on insect pollinators is increasing as greater percentages of land being converted to pollinator-dependent crops, such as soy and oil palm, than pollinator-independent crops, such as grains …

Assimilation Of Seasonal Moisture Variability In North America And Asia For The Last Millennium, Chang Liu

Graduate Theses and Dissertations

The seasonal tree-ring chronologies that recorded discrete moisture signal for warm and cool season have been used to reconstruct the North America Seasonal Precipitation Atlas (NASPA) by the point-by-point regression method, and the results indicated that they can fairly reproduce the seasonal precipitation variability in the past. Compared with reconstructions using only paleoclimate proxy data, the paleoclimate data assimilation (PDA) considers both proxy data and climate model output, so the PDA reconstructions are consistent with both the climate signals reflected by the proxy data and the physical mechanisms represented by climate models. Based on the tree rings with discrete seasonal …

The Systemic Punches: Displacement Experience Of Vulnerable Immigrants, Eric Andre

Graduate Theses and Dissertations

"The Systemic Punches: Displacement Experience of Vulnerable Immigrants" focuses on the impact of systems of state control such as immigration laws, policies, and practices that have been institutionalized and that have marginalized immigrants. In my thesis, I pay specific attention to inhuman acts of exclusion and discrimination resulting from the systemic barriers perpetuated by xenophobic and nationalist ideologies.

From this standpoint, my thesis exhibition employs interactive space, which includes visual art (drawing, sculpture ceramics), projection, video, and sound, as a means to explore the effects of the exclusive and discriminatory immigration policies and practices. Furthermore, it is designed to explore …

2+2=Cake: A Book Of Conversations About Possibilities In Business And Art, Elizabeth Ann Alspach

Graduate Theses and Dissertations

2+2=CAKE is a toolkit for people interested in creating their own economic container to support their livelihood. Calling upon the entrepreneurial experience of artists and creatives who founded or run organizations, the book and accompanying workbook and motivational posters serve as an incubator, buoy, and affirming resource for those looking to build the economic container in which they make their livelihood.