Life Sciences Commons^™

Comprehensive Poultry Supply Chain Model With Vertical And Horizontal Linkages: Implication Of Domestic And International Shocks, Hakan Unveren

Graduate Theses and Dissertations

According to USDA FAS, in 2017, the US was the largest broiler-producing country with 18.696 million metric tons and the second largest exporter of broiler products with 3.075 million metric tons (Brazil is the largest exporter with 3.847 million metric tons). Thus, around 83% of US production is consumed domestically. According to USITC, chickens are the most important protein source in the US, and Americans consume more chicken per capita than any other country. However, while the broiler industry is a key segment of US agriculture, it is underserved by large-scale supply-chain and trade models.

In this study, to fill …

Spatial Reorganization Of Histone-Like Nucleoid Structuring Proteins Caused By Silver Nanoparticles, Meaad Alqahtany

Graduate Theses and Dissertations

Silver nanoparticles (AgNPs) and ions (Ag+) can be the new generation of antibiotics due to their antimicrobial effects against bacteria and other microbes. Many studies have shown that AgNPs and suppress the growth of bacteria and damage the cell walls of the microbes; therefore, treating bacterial cells with AgNPs may be a promising method to terminate multi-resistant bacteria. In this work, the effect of AgNPs with two different surface coatings on the spatial reorganization of histone-like nucleoid structuring (H-NS) proteins in Escherichia coli bacteria was investigated using quantitative super-resolution fluorescence microscopy to understand the toxicity and antimicrobial mechanism of AgNPs. …

Characterization Of Microtubule Organizing Centers In The Genus Protostelium, Including Evolutionary Implications, Ethan Taylor Ozment

Graduate Theses and Dissertations

Microtubule organizing centers (MTOCs) are cellular regions of microtubule nucleation. The best known MTOCs are those associated with the centrosome, but several non-centrosomal MTOCs are known in eukaryotes, especially in land plants. MTOCs are poorly characterized across the breadth of amoebozoan diversity, but are well-known in certain amoebozoan lineages, including the genus of protosteloid slime molds Protostelium. The structure of the MTOC is known for two non-ciliated species, P. nocturnum and P. mycophaga, as well as P. aurantium, which can reversibly become ciliated under appropriate conditions. P. nocturnum and P. mycophaga have acentriolar centrosomal MTOCs while P. aurantium has a …

Implications Of Rice Cultivar Selection To Optimize Returns From Crop Insurance, David Ethan Branscum

Graduate Theses and Dissertations

Rice production differs from most other field crops by distinct differences in yields across cultivars and rice producers being paid for yield after post-harvest milling. Using eleven years (2003-2013) of Arkansas harvest data from performance trials in six different locations, hybrids have 19% higher paddy yields and head rice yield rate 1.7% lower than conventional cultivars. Given the 2014 Farm Bill’s emphasis on crop insurance as a risk management tool for producers, these variations in yield among cultivars have significant implications for rice producers. Comparing national level, crop insurance data on corn, soybeans and rice indicates rice producers strongly prefer …

Targeting Sec61Α By Ipomoeassin F Leads To Highly Cytotoxic Effect, Zhijian Hu

Graduate Theses and Dissertations

Ipomoeassin F is a flagship congener of a resin glycoside family that inhibits growth of many tumor cell lines with only single-digital nanomolar IC50 values. However, biological and pharmacological mechanisms of ipomoeassin F have been undefined. To facilitate exploration of the biological and pharmacological properties, we performed sophisticate SAR (Structure–activity relationship) studies of ipomoeassin F to understand its pharmacophore and structure properties so that we can design favorable probes for further biological investigation. By applying appropriate deviates that possess fluorescent groups and similar bio-activity, the target protein was found to be localized in endoplasmic reticulum (ER). Through biotin affinity pull …

Hormone Signaling, Gene Expression, And Mitochondrial Hormone Receptor Expression In Avian Muscle (Cells), Kentu Rushadd Lassiter

Graduate Theses and Dissertations

Mitochondria are vital to the proper growth and function of muscle cells since they’re responsible for the majority of ATP production used for cellular energy. Previous studies have investigated how differences in mitochondrial function affects feed efficiency (FE) in broilers phenotyped for High and Low FE. Low FE broilers have been shown to have increased levels of reactive oxygen species (ROS), thus contributing to higher levels of oxidative stress and damage seen in these birds. Global gene and protein expression studies conducted on breast muscle of the High FE and Low FE phenotypes have suggested that differences in mitochondrial function …

Evaluation Of Crop Tolerance And Weed Control In Corn And Grain Sorghum With Atrazine Replacements, Jacob Thomas Richburg

Graduate Theses and Dissertations

Atrazine is a foundational herbicide for weed control in both corn (Zea mays L.) and grain sorghum [Sorghum bicolor (L.) Moench] production. However, studies have shown that while atrazine may be an effective herbicide for preemergence and postemergence control of weeds, it also has risks. The low Koc of atrazine as well as its extensive use over the past 50 years have led it to become the most common groundwater contaminant near agricultural soils. Given these findings, atrazine has faced severe scrutiny while under consideration for reregistration. In the event that atrazine is not reregistered, corn and grain sorghum producers …

Effects Of Critical Reflection On University Students’ Cognitive Achievement In Agricultural Mechanization, Patterson P. Hilaire

Graduate Theses and Dissertations

Experiential learning continues to play a vital role in agricultural education and mechanization laboratories (Shoulders & Myers, 2013). An essential component of experiential learning is critical reflection. Critical reflection helps students process and construct meaning from laboratory experiences. A study conducted by Shoulders and Myers (2013) revealed that only 15.4% of the agricultural educators the researchers interviewed incorporated reflective practices laboratory experiences. The purpose of this study was to evaluate the effect of critical reflection on students’ achievement following five agricultural mechanization laboratory activities. The results from this study revealed that critical reflection had a consistently positive effect on immediate …

A Silicon Germanium Cmos Linear Voltage Regulator For Wireless Agricultural Applications, Aminta Naidili Castillo Robles

Graduate Theses and Dissertations

This thesis presents the design, simulation and test results of a silicon germanium (SiGe) complementary metal-oxide-semiconductor (CMOS) linear regulator. The objective of the circuit is to power other analog devices regardless of the load current and input voltage changes. The application of this regulator is to be part of a project developing a miniaturized semiconductor platform that can be inserted into stems of crops in order to measure data inside the plant and then send it wirelessly to the user. The linear regulator was designed on a BiCMOS SiGe 0.13µm which is a GlobalFoundries process. It has been tested at …

Comparison Of Physical Intensity Between Interactive Video Game Cycling And Conventional Stationary Cycling In Adolescents With High Functioning Autism Spectrum Disorder, Tariq Mohammed Alsoqairan

Graduate Theses and Dissertations

Background: Obesity has become a serious health concern in adolescents with autism spectrum disorder (ASD). Researchers have indicated that sedentary behaviors, especially technological activities, such as video games and other forms of screen-based activities is the main barrier to participate in physical activities. Active video games have demonstrated the efficacy in increasing physical activity and reducing body weight in children and adolescents with disabilities.

Purpose: The purpose of the study was to examine the exercise intensity and enjoyment level of interactive video game cycling (IVGC) in comparison with conventional stationary cycling (CSC) during matched number of sessions utilizing the same …

Validity And Reliability Of A 5-Minute Web-Camera Based Eye Tracking Test To Assess Visual Memory And Cognition, Emily Bates

Graduate Theses and Dissertations

There are approximately 5.7 million Americans currently living with Alzheimer’s Disease (AD). Early detection of cognitive impairment allows for earlier treatment, potentially slowing or halting cognitive decline. A 30-min web-camera eye tracking assessment (30-min VPC) has been validated as a tool to predict AD risk. However, a shorter version would allow for greater scalability and improve user experience. The purpose of this study was to: 1) determine the validity of the 5-minute web-camera based VPC test with the 30-min test, 2) determine the test-retest reliability of the 5-min test, 3) compare the 5-minute test scores of cognitively intact adults (18-39 …

Amphibian And Reptile Community Responses To Forest And Riparian Disturbance, Jacquelyn Christine Guzy

Graduate Theses and Dissertations

Riparian zones are transitional, semi-terrestrial areas regularly influenced by freshwater. These areas serve as dispersal corridors for many animal and plant species and ultimately function as important reservoirs of biodiversity in altered landscapes. While much of the riparian habitat in the United States has been affected by anthropogenic activities, management actions may mitigate potentially negative influences of these activities. For example, Streamside Management Zones (i.e., riparian buffers; SMZs) are commonly implemented within managed forests to protect water quality, but may also provide habitat for riparian-associated wildlife. Yet, little research has rigorously addressed the value of SMZs for wildlife, particularly cryptic …

The Evaluation Of Low-Use-Rate Zinc Fertilization Strategies On Seedling Canopy Coverage, Zn Concentration, Biomass, And Grain Yield, Maxwell David Coffin

Graduate Theses and Dissertations

Zinc (Zn) is the most common micronutrient deficiency in flooded rice (Oryza sativa L.). Some new Zn fertilization methods have been advertised, but have limited research supporting their efficacy. This study mainly compared the effect of Zn-seed treatment rate in combination with other low-use-rate Zn-fertilization methods to the standard of 11 kg Zn ha-1 as ZnSO4 on rice early-season canopy cover, tissue-Zn concentration, and grain yield. A secondary objective evaluated an alternative method (to seed treatment with ZnO) of enhancing seed-Zn concentration using post-heading foliar-Zn application on seedling tissue-Zn concentration and grain yield. For the main objective, rice seed was …

Cool And Warm Season Climate Signals In Tree Rings From North America, Max Carl Arne Torbenson

Graduate Theses and Dissertations

Earlywood (EW) and latewood (LW) ring-width chronologies have become an increasingly important proxy in paleoclimate reconstructions. These subannual variables can provide estimates of past hydroclimate variability for seasonal windows that total ring-widths cannot resolve. The strength of the relationship between EW and LW series may influence what type of paleoclimate information is embedded within the tree-ring series. High correlations (> 0.70) between EW and LW are recorded for much of the continent but the magnitude of correlation varies greatly across space and species boundaries. Using four LW chronologies from shortleaf pine, the North American conifer species displaying the lowest EW-LW …

Biogeography Of Endemic Dragonflies Of The Ozark-Ouachita Interior Highlands, Wade Alexander Boys

Graduate Theses and Dissertations

A common pattern across many taxonomic groups is that relatively few species are widespread while the majority are restricted in their geographic ranges. Such species distributions are used to inform conservation status, which poses unique challenges for rare or cryptic species. Further, priority status is often designated within geopolitical boundaries, which may include only a portion of a species range. This, coupled with lack of distributional data, has resulted in species being designated as apparently rare throughout some portions of their range, which may not accurately reflect their overall conservation need. The Interior Highlands region of the central United States …

Using Cover Crops To Recycle Nutrients In An Arkansas No-Till Corn System, Kelsey Lynn Hoegenauer

Graduate Theses and Dissertations

Cover crops can provide many benefits to cropping systems including erosion control, weed suppression, and increased soil organic matter. Regardless of the intended goal for using cover crops, the changes to the nutrient flux in a cropping system caused by cover crops retaining and recycling nutrients needs to be considered in order to maximize the productivity of the following commodity crops. This research encompassed complementary greenhouse, field, and laboratory experiments to evaluate nutrient uptake and release by tillage radish (Raphanus sativus) and cereal rye (Secale cereale) cover crops, as well as the subsequent early-season recovery of recycled nutrients by the …

Diffuse Reflectance Spectroscopy To Quantify In Vivo Tissue Optical Properties: Applications In Human Epithelium And Subcutaneous Murine Colon Cancer, Gage Joseph Greening

Graduate Theses and Dissertations

Colorectal cancer is the 4th most common and 2nd deadliest cancer. Problems exist with predicting which patients will respond best to certain therapy regimens. Diffuse reflectance spectroscopy has been suggested as a candidate to optically monitor a patient’s early response to therapy and has been received favorably in experimentally managing other cancers such as breast and skin. In this dissertation, two diffuse reflectance spectroscopy probes were designed: one with a combined high-resolution microendoscopy modality, and one that was optimized for acquiring data from subcutaneous murine tumors. For both probes, percent errors for estimating tissue optical properties (reduced scattering coefficient and …

Comparative Plasma Proteomics In Muscle Atrophy Induced By Cancer Cachexia And Hindlimb Unloading, Kirsten Rene Dunlap

Graduate Theses and Dissertations

Introduction: Muscle atrophy results from a dysfunction in protein turnover that leads to loss of mass and function and occurs concurrently with multiple pathologies such as cancer and extended bed rest. Atrophy reduces overall quality of life while increasing morbidity and mortality. Currently, efficacious therapeutic interventions to treat and prevent muscle wasting in all its forms are lacking, however if conserved mechanisms can be identified between wasting conditions, this would aid in the development of multipurpose therapeutics to ameliorate this pathology. Purpose: To examine circulating factors present across atrophic pathologies. Methods: 35 male C57BL/6J mice were assigned to hindlimb unloading …

Alcohol Use, Dietary, And Exercise Behaviors: A Latent Profile Analysis Of Young Adult Lifestyle Behaviors, Ryan Wesley Grant

Graduate Theses and Dissertations

As individuals enter adulthood, their lifestyles and lifestyle behaviors begin to change drastically. These lifestyle behavior changes in emerging adulthood provide a foundation for future health behaviors that often persist through all of adulthood. The aim of this study was to use Latent profile analyses (LPA) to discover distinct profiles of homogenous groups of young adults based on alcohol, diet, and exercise behaviors. Overall, five distinct profiles for both males and females were identified: Moderates, Unhealthy Eaters, Medium Drinkers, Healthier Eaters and Exercisers, and Heavy Drinkers. Heavy Drinkers and Unhealthy Eaters were the highest risk groups and reported the highest …

A Phenomenological Study Of The Lived Experiences Of Counseling Students In A Co-Facilitated Experiential Group, Alexandra Meyers

Graduate Theses and Dissertations

Research in the fields of experiential learning, group psychotherapy, and neuroscience has supported the inclusion of the experiential group in counseling training programs due to the potential for positive impact on students’ personal and professional development (Badenoch & Cox, 2010; Denninger, 2010). Investigations exploring counseling students’ experiences of the experiential group have been primarily limited to quantitative studies, while in-depth qualitative inquiry has been minimal. Additionally, an extensive review of the literature has found there have been no qualitative studies examining experiential groups co-facilitated by a course instructor and a doctoral student. The purpose of this phenomenological study was to …

Volumetric Muscle Loss: The Role Of Physical Activity And Autologous Repair On Force Recovery And Signaling Pathways, Richard Perry

Graduate Theses and Dissertations

Volumetric muscle loss affects both military and civilian persons. The hallmark of this injury is incomplete muscle regeneration, excessive fibrosis, and chronic inflammatory signaling resulting in permanent functional loss. Since permanent functional loss drastically reduces quality of life, many studies have been conducted to improve force recovery. Current scientific literature considers a repair strategy of either devitalized scaffolds infused with growth factors or viable tissue plus activating factors to be the more promising interventions for optimal force recovery. PURPOSE The purpose of this study is to incorporate autologous repair and physical activity and observe the effects of muscle force recovery …

Optimization Of The Light Environment For Broiler Chickens, Douglas J. Aldridge

Graduate Theses and Dissertations

The use of artificial light sources has been necessitated by the use of fully enclosed rearing facilities for improved environmental control. Light Emitting Diodes (LED) have been developed as a light source that reduce the utilities required to provide equal light to that of incandescent sources. The following reports were carried out to investigate the effects of two light color temperatures, light intensity and light intensity gradients on broiler chicken production and behavior. The first investigation consisting of two consecutive trials investigated the effect of two light color temperatures (2700 K and 5000 K) in addition to the preference for …

Assessment Of Control Of Ppo-Resistant Palmer Amaranth And Salvage Options In Herbicide-Resistant Cotton, Wyatt D. Coffman

Graduate Theses and Dissertations

Palmer amaranth has been the most limiting weed in cotton production in the state of Arkansas for many years. Recently, resistance of Palmer amaranth to the protoporphyrinogen oxidase (PPO)-inhibiting site of action has been discovered at various locations across the cotton-producing region of the state. Cotton varieties have been developed with resistance to synthetic auxin (WSSA Group 4) herbicides. However, research to date has shown PPO-resistant Palmer amaranth to be more difficult to control with herbicides that target alternative sites of action. Herbicide efficacy is also known to vary with weed size, varying spray parameters, and environmental conditions. Preliminary research …

Analysis And Conservation Of Native Forests At Kessler Mountain Fayetteville, Arkansas, Alan James Edmondson

Graduate Theses and Dissertations

Kessler Mountain in Fayetteville Arkansas has long been recognized for its beauty and natural resources. Parts of Kessler Mountain have been homesteaded and developed in the past, but most of the mountain has remained relatively undisturbed. The planned development of over 4,000 housing units to cover Kessler Mountain stimulated controversy and consideration of other management alternatives. A twist of fate involving an economic recession, a dedicated group of outdoor recreation enthusiasts, and environmental conservationists led to the permanent protection of 384 acres in the Kessler Mountain Regional Park. To help evaluate the natural resources at Kessler Mountain, forest composition, structure, …

Feedforward And Feedback Signals In The Olfactory System, Srimoy Chakraborty

Graduate Theses and Dissertations

The conglomeration of myriad activities in neural systems often results in prominent oscillations. The primary goal of the research presented in this thesis was to study effects of sensory stimulus on the olfactory system of rats, focusing on the olfactory bulb (OB) and the anterior piriform cortex (aPC). Extracellular electrophysiological measurements revealed distinct frequency bands of oscillations in OB and aPC. However, how these oscillatory fluctuations help the animal to process sensory input is not clearly understood. Here we show high frequency oscillations in olfactory bulb carry feedforward signals to anterior piriform cortex whereas feedback from the aPC is predominantly …

Development And Evaluation Of Selected Chemoprophylaxis Candidates And A Candidate Live-Attenuated Vaccine For Prevention Of Histomoniasis In Turkeys, Lesleigh Beer

Graduate Theses and Dissertations

Histomoniasis, commonly known as blackhead disease, has increased in prevalence due to the regulatory ban of prophylactics and therapeutics within the past 30 years. The objective of this thesis was to evaluate the efficacy of selected dietary chemoprophylaxis candidates as well as an in vitro live-attenuated vaccine candidate Histomonas meleagridis for prevention of histomoniasis. Chapter one addresses deoxycholic acid and a biliogenic diet intended to endogenously increase production of this secondary bile acid. Deoxycholic acid was effective in vitro but failed to prevent histomoniasis when evaluated during the in vivo experimental disease trial with turkeys. The biliogenic diet did not …

Reducing The Risk: Psychological And Technological Approaches For Improving Handwashing Practices In The Foodservice Industry, Jeffrey Allan Clark

Graduate Theses and Dissertations

As Americans are spending greater portions of their dollar on food consumed outside the home, the foodservice industry plays more of an integral part of daily existence compared to previous generations. Given the numerous annual foodborne illness outbreaks that threaten human lives while undermining confidence in the food supply, food safety is a pertinent issue for industry stakeholders, government regulators, and consumers. Food worker handwashing reduces the risk of foodborne illness transmission, yet compliance with this simple behavior is a complex problem. This dissertation addresses, predominantly, the issue of sub-optimal handwashing practices through applying psychology and technology, including wearable computers …

Daily To Seasonal Moisture Signals Present In Sub-Annual Tree-Ring Data, Ian Howard

Graduate Theses and Dissertations

In recent decades, there has been an increase in the development of sub-annual earlywood (EW) and latewood (LW) width tree-ring chronologies that have been used to make long-term inferences about discrete seasonal moisture variability for different regions of North America. This doctoral research developed a new network of EW, LW, and adjusted latewood (LWa) tree-ring chronologies from the western Great Plains. These chronologies were used to reconstruct 300+ years of spring and summer moisture variability over the northern and southern Plains. The reconstructions document new information about the long-term seasonal climate history of the Great Plains, including the unusual nature …

Phylogenomics And Geometric Morphometrics Define Species Flocks Of Snowtrout (Teleostei: Schizothorax) In The Central Himalayas, Binod Regmi

Graduate Theses and Dissertations

Schizothorax (Snowtrout) is a genus of medium-sized minnows (Cypriniformes) inhabiting glacier-fed streams, rivers, and lakes in the Himalayas. There are more than 30 species of Schizothorax across the region. The speciation and diversity of the Snowtrout in the vast hinterlands of the Himalayan Region has not been fully explored. Three species in Lake Rara, Western Nepal are considered a species flock, comprising endemic ecotypes that are morphologically differentiated and reproductively isolated.

My dissertation research examined the diversity of Schizothorax in the Central Himalayan region and evolutionary relationships among species distributed in the Tibet, Central and Southeast Asia. Chapter I describes …

Defining The Genetic Regulation Of Appressorium Formation In Cercospora Zeae-Maydis, Hazel Apiyo Buyu

Graduate Theses and Dissertations

Cercospora zeae-maydis is one of the primary pathogens associated with gray leaf spot, one of the most damaging foliar diseases of maize in the world. Gray leaf spot can be managed to some extent by cultural practices and fungicide applications. To infect maize, C. zeae-maydis grows towards stomata and forms infectious structures, termed appressoria, over stomatal pores. Prior research on the pathogen revealed that appressorium formation is crucial for foliar infection. Although several genes involved in pathogenesis have been identified in C. zeae-maydis, the molecular regulation of appressorium formation in this pathogen is poorly understood. Specifically, how the fungus senses …