Digital Commons Network^™

Community- Versus School-Based Mentoring Matches: Do Mentees’ Parents Differ In Family Risk, Perceived Support Or Reasons For A Mentor?, Meredith Sourk

Graduate Theses and Dissertations

This study explores whether the parents or guardians of youth participating in community-based (CBM) and school-based (SBM) mentoring programs differ in their level of family stress, economic adversity and perceived social and community support. Participants were 131 parents of youth in either CBM (n = 79) or SBM (n = 52) programs sponsored by Big Brothers Big Sisters of Canada (BBBS-Canada). Parents completed an online survey that assessed demographic characteristics and involvement in BBBS-C programs. Additional measures assessed family stress, economic adversity, perceived support (interpersonal, community), and reasons for wanting a mentor. Parents of youth in CBM matches were less …

Effects Of Hydration And Mineralization On The Mechanical Behavior Of Collagen Fibrils, Marco Fielder

Graduate Theses and Dissertations

Bone is a composite biomaterial with a structural load-bearing function. Understanding the biomechanics of bone is important for characterizing factors such as age, trauma, or disease, and in the development of scaffolds for tissue engineering and bioinspired materials. At the nanoscale, bone is primarily composed of collagen protein, apatite crystals, and water. Though several studies have characterized nanoscale bone mechanics as the mineral content changes, the effect of water, mineral, and carbon nanotube (CNT) content and distribution in fibril gap and overlap regions is unexplored. This study used molecular dynamics to investigate the change in collagen fibril deformation mechanisms as …

Zinc Injection As A Novel Castration Method And Carry-Over Effects Of Growth-Promoting Implants In Beef Cattle, Jase Joseph Ball

Graduate Theses and Dissertations

In experiment 1, crossbred bull calves (n = 31; body weight (BW) = 114.3 ± 26.3 kg; age = 119 ± 18.4 d) were allocated to treatments by BW and birthdate. Twenty-seven bull calves were allocated to 3 injectable castration treatments (n = 9 calves/injectable castration treatment) to reflect 3 dosage levels of zinc. Intact bulls had greater (P < 0.001) serum testosterone concentrations compared to bulls injected with zinc. In experiment 2, crossbred beef bulls (n = 180) were blocked by initial BW (337 ± 10.9 kg; 6 blocks) and assigned randomly to 1 of 3 treatments on d 0: 1) INJ; received 1 mL (100 mg Zn) of a Zn solution in each testis, 2) BAN; banded, 3) BUL; intact. Final BW was greater (P < 0.01) for INJ (672 kg) and BUL (686 kg) compared to BAN (611 kg). Serum haptoglobin concentration was greater (P < 0.01) in INJ compared to BUL and BAN on d 1, 3, 5, and 7. Zinc injection resulted in sterilization but not castration in feedlot bulls although it was efficacious in castration of young bulls at branding. In experiment 3, crossbred beef steers (n = 106; BW = 96 ± 3.9 kg; age = 74 ± 2.0 d) were blocked by parity of dam (≤ 2 or > 2 parities), stratified by BW, calf age, calf sire, cow BW and body condition score to 1 of 4 treatments: 1) RALG, Ralgro, Ralgro, Revalor XS, at branding (D 0), weaning (D 156), and feedlot processing (D 325), 2) COMP, Component …

Involvement Of The Ino80 Complex In Chromosome Segregation, Jesus Moreno

Graduate Theses and Dissertations

Chromatin remodeling complexes are multi-protein complexes that regulate the dynamics of the nucleosomes in the genome. The INO80 chromatin remodeling complex participates in varied biological processes such as: transcription, DNA repair, DNA replication and chromosome integrity. It catalyzes the eviction of the H2A.Z variant histone as well as whole nucleosome eviction. This complex is comprised of 15 subunits and the contribution of each to chromosome segregations remains unknown. To evaluate the contribution of each subunit to chromosome segregation, we tested deletion mutants of the non-essential subunits for DNA content and benomyl sensitivity. Also, we assessed members of the SWR1 and …

Mitochondrial Mrna Translation Is Required For Maintenance Of Oxidative Capacity, David Lee

Graduate Theses and Dissertations

Oxidative metabolism is required to produce adequate energy to sustain human life. A primary example of deteriorating oxidative capacity is seen in the cardiac musculature during chronic heart failure. This suggests that by improving oxidative potential, chronic heart disease could be mitigated and one approach to accomplish this may be through targeting the mt-mRNA translation system. Purpose: This investigation’s purpose was to characterize disruptions in mt-mRNA translation machinery in multiple forms of cardiomyopathy and to determine if mitochondrial mRNA translation initiation factor (mtIF2) is necessary to maintain oxidative capacity in cardiomyocytes. Methods Using a combination of animal and cell culture …

Soil Properties That Influence The Occurrence Of Hydrogen Sulfide Toxicity In Rice Fields, Julia Marie Fryer

Graduate Theses and Dissertations

Rice (Oryza sativa L.) producers face many challenges throughout each growing season. Hydrogen sulfide (H2S) toxicity is a physiological disorder where sulfate (SO42-) is excessively reduced to the toxic gas, H2S. This can reduce yield and, in severe cases, result in crop death. The main research objectives were to: i) understand chemical and physical characteristics in soils prone to H2S toxicity, ii) determine influential soil characteristics on the incidence of H2S toxicity, iii) determine ammonium sulfate ((NH4)2SO4) fertilizer additions influence on H2S toxicity, and iv) predict when and where H2S will occur. Three greenhouse experiments were conducted using Arkansas field …

Combining Translational And Functional Genomic Approaches To Augment Management Strategies Of Plant Parasitic Nematodes, Sandeep Sharma Khatiwada

Graduate Theses and Dissertations

Plant-parasitic nematodes pose a major threat to crop yield worldwide. Discontinued use of harmful chemicals has prompted the search for alternative management strategies that are effective yet environmentally friendly. Harpin proteins, which are derived from bacteria, and nematophagous fungi, natural predators of nematodes, are ideal for biological control of plant-parasitic nematodes. However, research on the efficacy of harpin proteins on nematodes, and biology of nematophagous fungi is minimal. Previously, a taxonomically uncharacterized nematophagous fungus designated ARF18 effectively suppressed nematode populations in soil. The overarching goal of this dissertation is to utilize applied and functional genomic approaches to augment management of …

Hierarchical Bayesian Regression With Application In Spatial Modeling And Outlier Detection, Ghadeer Mahdi

Graduate Theses and Dissertations

This dissertation makes two important contributions to the development of Bayesian hierarchical models. The first contribution is focused on spatial modeling. Spatial data observed on a group of areal units is common in scientific applications. The usual hierarchical approach for modeling this kind of dataset is to introduce a spatial random effect with an autoregressive prior. However, the usual Markov chain Monte Carlo scheme for this hierarchical framework requires the spatial effects to be sampled from their full conditional posteriors one-by-one resulting in poor mixing. More importantly, it makes the model computationally inefficient for datasets with large number of units. …

Engineering The Structure Of The Human Acidic Fibroblast Growth Factor To Enhance Its Stability And Cell Proliferation Activity, Julie Davis Eberle

Graduate Theses and Dissertations

Human acidic fibroblast growth factor (hFGF1) is a protein well known for its role in cell growth and differentiation. To elicit these cell-signaling processes, hFGF1 non-selectively binds to any one of the seven cell surface hFGF receptor isoforms. Due to its significant involvement in tissue repair activity, hFGF1 is a prime candidate for novel wound healing therapeutics. However, one drawback toward its use as a novel wound healing therapeutic is the poor inherent thermal stability of hFGF1, as it has been found to unfold near physiological temperature. The cause of this instability is strong electrostatic repulsion created by a dense …

Towards Quantifying Relevant Land Cover Change: A Case Study In The Central Flyway Of The Monarch Butterfly, Hanna Lenee Ford

Graduate Theses and Dissertations

Over the past 20 years notable decreases in monarch butterfly populations have led researchers to begin evaluating the landscape for changes and seeking out opportunities for enacting conservation programs to better support their survival. The monarch butterfly has recently come under consideration for listing under the Endangered Species Act which has created a need for a more informed view of the landscape through which the migrate and breed, the central United States. In this research three spatially-explicit models are explored using the most applicable datasets currently available to address pressing policy and land manager decisions regarding monarch butterfly and pollinator …

Species And Cultural Management Of Earthworms On Golf Course Turf In Arkansas And Oklahoma, Paige Elizabeth Boyle

Graduate Theses and Dissertations

As earthworms feed, they can egest soil and nutrient-rich aggregates (casts) on the soil surface. In low-cut turfgrass systems, such as golf course greens, tees, and fairways, surface casting can result in a muddy playing surface, ball roll issues, weed and pest invasion, reduced aesthetics, surface softening, and reduced photosynthesis. Because the use of pesticides for earthworm control is illegal in the U.S., earthworm casting must be managed through cultural practices. Sand topdressing is one method of earthworm control studied for use on golf courses, with the supposition being that the abrasive sand particles will deter the soft-bodied earthworms from …

A Comparison Of Craniofacial Asymmetry In Gorilla Gorilla Gorilla And Pan Troglodytes Troglodytes, Ashly Noel Romero

Graduate Theses and Dissertations

Fluctuating asymmetry (FA) – random deviations from bilateral symmetry in an organism’s paired features – is a good candidate for investigating developmental stability. This easily accessible measurement can be used to understand the relationship between stress and development across organisms, and growth rate plays a vital role in developmental processes. Few studies have investigated craniofacial FA in non-human primates, and those that have suggest that levels of FA are higher in slower growing species. This study examines craniofacial FA in two primate species (Pan troglodytes troglodytes and Gorilla gorilla gorilla; n=81) to elucidate the effect of growth rate on FA …

Experimental And Model-Based Terahertz Imaging And Spectroscopy For Mice, Human, And Phantom Breast Cancer Tissues, Tyler Bowman

Graduate Theses and Dissertations

The goal of this work is to investigate terahertz technology for assessing the surgical margins of breast tumors through electromagnetic modeling and terahertz experiments. The measurements were conducted using a pulsed terahertz system that provides time and frequency domain signals. Three types of breast tissues were investigated in this work. The first was formalin-fixed, paraffin-embedded tissues from human infiltrating ductal and lobular carcinomas. The second was human tumors excised within 24-hours of lumpectomy or mastectomy surgeries. The third was xenograft and transgenic mice breast cancer tumors grown in a controlled laboratory environment to achieve more data for statistical analysis.

Experimental …

Development Of Microdialysis Probes In Series Approach Toward Eliminating Microdialysis Sampling Calibration: Miniaturization Into A Pdms Microfluidic Device, Randy Espinal Cabrera

Graduate Theses and Dissertations

A new microdialysis sampling method and microfluidic device were developed in vitro. The method consisted of using up to four microdialysis sampling probes connected in series to evaluate the relative recovery (RR) of different model solutes methyl orange, fluorescein isothiocyanate (FITC)-dextran average mol. wt. 4,000 (FITC-4), FITC-10, FITC-20, and FITC-40. Different flow rates (0.8, 1.0, and 1.5 µL/min) were used to compare experimentally observed relative recoveries with theoretical estimations. With increasing the number of probes in series, the relative recovery increases and ~100% (99.7% ± 0.9%) relative recovery for methyl orange was obtained. For larger molecules such as fluorescein isothiocyanate …

A Multi-Objective Affinity-Based Savings Algorithm For Improving Processes In Centralized Warehousing Operations, Mckenlee M. Coco

Graduate Theses and Dissertations

Traditional approaches to improving material management processes in warehousing operations tend to focus on one of three major areas: facility design, order picking and sorting, and order batching. In an effort to improve total system savings, a new affinity function is developed and applied to batching logic to create a multi-objective problem. The proposed multi-objective function incorporates user input to increase adaptability to changing demand and flexibility to changing requirements. Computational experience shows the new function leads to solutions that deviate no more than 25% from the most efficient distance based picking route by the same batching logic, while creating …

Multiscale Investigation Of The Behavior Of Heart Valve Interstitial Cells In Response To Pathological Shape And Mechanical Stimulation, Ngoc Thien Lam

Graduate Theses and Dissertations

Our works aim to provide an insight into how aortic valve interstitial cells (VICs) respond to pathological shape and mechanical stimulation as well as the potential signaling pathway that mediates these responses, using a multiscale approach. A single cell model was developed to investigate the effect of altered shape on valve cell function as valve cells were reported to significantly deform during the cardiac cycle. Single VICs were controlled to take on features with different width-to-length aspect ratios that corresponded to the steady-state shapes adopted by VICs when stretched to 0%, 10% and 20%, respectively. It appeared that single VIC …

Rapid And Sensitive Detection Of Escherichia Coli O157:H7 Using A Qcm Sensor Based On Aptamers Selected By Whole-Bacterium Selex And A Multivalent Aptamer System, Xiaofan Yu

Graduate Theses and Dissertations

Escherichia coli O157:H7 is one of the top five pathogens contributing to foodborne diseases, causing an estimated 2,138 cases of hospitalization in the US each year. The extremely low infectious dose demands for more rapid and sensitive methods to detect E. coli O157:H7. The objective of this study is to select aptamers specifically binding to E. coli O157:H7 using whole-bacterium SELEX (Systematic Evolution of Ligands by Exponential Enrichment) and to create a multivalent aptamer system by rolling circle amplification (RCA) with the selected aptamer sequence for sensitive detection of E. coli O157:H7 using a quartz crystal microbalance (QCM) sensor. Briefly, …

Survey Of Hydration Knowledge And Behavior In Youth Mountain Bike Teams, Natasha Brand

Graduate Theses and Dissertations

Many youth sports organizations recognize the importance of educating on hydration practices and awareness, although according to recent research current hydration education is not correlating to effective practices. PURPOSE: The purpose of this study was to assess and describe the hydration knowledge and behavior of student-athletes participating in competitive junior high and high school mountain bike teams, in order to substantiate further research. METHODS: A total of 133 male and female participants, ranging from 11-18 years were surveyed on their hydration knowledge and behavior. All participants were apparently healthy and were active members of a National Interscholastic Cycling Association (NICA) …

The Effect Of Teacher Race On Student Perceptions In Low-Income Schools, Benton M. Brown

Graduate Theses and Dissertations

In the wake of the Brown v. Board of Education (1954) decision, thousands of teachers of color lost their jobs as black students were integrated into mostly white schools. The number of black teachers in schools across the United States has never recovered resulting in a teaching workforce that is less diverse than the student population that they teach. Many studies have examined the possible impact of this discrepancy including the possibility that this has contributed to the black-white achievement gap that exists in the United States. Other studies have examined the non-academic impacts of a less diverse workforce including …

An Investigation Into The Suitability Of Sulfate-Reducing Bacteria As Models For Martian Forward Contamination, Maxwell M. W. Silver

Graduate Theses and Dissertations

The NASA Planetary Protection policy requires interplanetary space missions do not compromise the target body for a current or future scientific investigation and do not pose an unacceptable risk to Earth, including biologic materials. Robotic missions to Mars pose a risk to planetary protection in the forms of forward and reverse contamination. To reduce these risks, a firm understanding of microbial response to Mars conditions is required. Sulfate-reducing bacteria are prime candidates for potential forward contamination on Mars. Understanding the potential for forward-contamination of sulfate-reducers on Mars calls for the characterization of sulfate-reducers under Mars atmosphere, temperature, and sulfate-brines. This …

Characterization Of Bacteriorhodopsin And Halorhodopsin Reconstituted In Lipid Bilayer Membranes, Joel Domkam Kamwa

Graduate Theses and Dissertations

Motivated to produce electricity with photon activated ion pumps, the main purpose of this work was to characterize the photosynthetic membrane proteins bacteriorhodopsin (proton pump) and halorhodopsin (chloride pump). The proteins were re-suspended in lipid bilayers. For this work, an experimental set-up was built which included: chambers for lipid bilayer formation and characterization, lasers for ion pump activation, and an AxoPatch electrophysiology system for small photocurrent measurement. Lipid bilayer membranes were formed using mostly folding method: folding two monolayers together. The membranes were characterized by their resistance, capacitance, and generated photocurrent. Photocurrent was generated upon illumination of lipid-protein membranes with …

Bayesian Network Modeling And Inference Of Gwas Catalog, Qiuping Pan

Graduate Theses and Dissertations

Genome-wide association studies (GWASs) have received an increasing attention to understand genotype-phenotype relationships. The Bayesian network has been proposed as a powerful tool for modeling single-nucleotide polymorphism (SNP)-trait associations due to its advantage in addressing the high computational complex and high dimensional problems. Most current works learn the interactions among genotypes and phenotypes from the raw genotype data. However, due to the privacy issue, genotype information is sensitive and should be handled by complying with specific restrictions. In this work, we aim to build Bayesian networks from publicly released GWAS statistics to explicitly reveal the conditional dependency between SNPs and …

Nitrous Oxide Emissions From Rice Production On A Silt-Loam Soil In Arkansas, Casey Rector

Graduate Theses and Dissertations

Rice (Oryza sativa L.) is a common crop grown in Arkansas under flooded-soil conditions. The saturated to nearly saturated soil makes rice production an ideal environment for the production of potent greenhouse gases, such as nitrous oxide (N2O). The objectives of this study were to i) evaluate the impact of water management practice (full-season-flood and intermittent-flood) and cultivar (pure-line and hybrid) on N2O fluxes, season-long N2O emissions, and global warming potential (GWP; 2016) and ii) evaluate the impact of tillage practice [conventional tillage and no-tillage (NT)] and type of urea fertilizer [ N-(n-butyl) thiosphosphoric triamide (NBPT)-coated and non-coated urea] on …

An Evaluation Of Breeding, Agronomic, And Processing Methodologies Of Vegetable Soybean (Edamame) To Increase Domestic Production In The United States Market, David Octor Moseley

Graduate Theses and Dissertations

Edamame is a food-grade soybean (Glycine max (L.) Merrill) that is either harvested immature (R6 stage) or after plant maturity (R8 stage). At R6, the premium product will have crescent- shaped large green pods and gray pubescence. At R8, the seed will either have stayed green or will have turned yellow, black, or brown. Edamame is a healthy snack with a sweet flavor and firm texture. The edamame market is growing in the United States, creating a need for more adapted varieties. The genetic diversity is low among adapted large-seeded breeding lines. Finding diverse accessions will help develop larger and …

Evaluation Of Dicamba Off-Target Movement And Subsequent Effects On Soybean Offspring, Gordon Travis Jones

Graduate Theses and Dissertations

Commercial launch of cotton with resistance to dicamba, glyphosate, and glufosinate occurred in 2015 and launch of soybean with resistance to dicamba and glyphosate occurred in early 2016. It is likely that non-dicamba-resistant soybean will be planted in close proximity to dicamba-resistant soybean and cotton. Therefore, experiments were conducted to examine the distance dicamba moves during an application using commercial application equipment, as well as the effect the drift events have upon soybean offspring. Additional experiments were designed to investigate the effect glyphosate addition to dicamba has upon soybean growth and yield as well as possible effects on offspring. Lastly, …

Genetic And Phytopathological Studies On Charcoal Rot Resistance In Soybean [Glycine Max (L) Merr.], Marcos Paulo Da Silva

Graduate Theses and Dissertations

Charcoal rot of soybean (Glycine max (L.), caused by Macrophomina phaseolina is a disease of economic significance in the United States. The identification and quantification of the resistance is difficult, and very little is known about the genetics and markers linked to the charcoal rot (CR) resistance genes. Current assay methods can be time consuming, and data may vary between tests. The objectives of this study were to 1) create a robust seed plate assay (SPA) for CR resistance by comparing results with cut-stem and CFUI assays; 2) correlate and compare field data disease assessments with SPA; 3) identify QTLs …

Microbiome Of Commercial Broilers Through Evisceration And Immersion Chilling, John A. Handley

Graduate Theses and Dissertations

The United States poultry industry generated 38.6 billion pounds (17,500 metric ton) of meat in 2014 which averaged to 121 pounds (55 kg) per individual of the U.S that same year. Of that meat generated by the poultry industry, an estimated 1 million cases of Salmonellosis will occur. Out of the 1 million cases approximately 40, 000 to 50,000 will be confirmed cases by the CDC. Recently, the USDA has requested changes in the inspection process and are currently allowing processors more freedom to utilize innovation to drive the increase in safer and more desirable foods. The new standards set …

Combining Microdialysis And Electrophysiology In Cerebral Cortex To Delineate Functional Implications Of Acetylcholine Gradients, Tazima Nur

Graduate Theses and Dissertations

The neuronal network in cerebral cortex is a dynamic system that can undergo changes in collective neural activity as the organism changes its behavior. For example, during sleep and quiet restful awake state, many neurons tend to fire together in synchrony. In contrast, during alert awake states, firing patterns of neurons tend to be more asynchronous, firing more independently. These changes in population-level synchrony are defined as changes in cortical state. Response to sensory input is state-dependent, i.e., change in cortical state can impact the sensory information processing in cortex and introduce trial-to-trial variability in response to the same repeated …

The Effects Of Super-Dosing Phytase On Nursery And Grower Pigs, Joshua Paul Knapp

Graduate Theses and Dissertations

To determine the effects of super-dosing on pigs fed phosphorous and calcium adequate or deficient diets (Experiment 1); the optimum level of corn express phytase (CEP, Experiment 2); and the effects of xylanase/phytase on growth performance (Experiment 3) in pigs fed reduce nutrient diets, weaned pigs were blocked with initial body weight (BW) and allotted to dietary treatments. Treatments were: Positive control (PC), P/Ca adequate diets (NRC 2012); Negative Control (NC), low P (-0.15%) and Ca (-0.12%), +0, 1000, and 4000 FTU/kg of CEP in both PC and NC (Experiment 1); PC, P/Ca adequate diets; NC, decreased P (0.15%) and …

The Effect Of Napping On Sleep Quality And Quantity In Healthy And Concussed Collegiate Athletes, Katie Stephenson-Brown

Graduate Theses and Dissertations

Clinicians are increasingly prescribing a regulated sleep schedule to athletes post injury; however, baseline sleep habits of collegiate athletes are unknown. Moreover, the connection between napping and sleep quality and quantity has not been studied in collegiate athletes. Therefore, the purpose of this study is to investigate napping behaviors and their effects on sleep quantity and quality in concussed and non-concussed collegiate athletes. In a sample of 233 non-concussed collegiate athletes, 74% (172/233) of participants reported napping. Napping was not significantly associated with sleep quantity (χ 2 (2) = .23, p = .64) or quality (χ 2 (1) = .42, …