Digital Commons Network^™

Construction Of 3d Biomimetic Tissue Niches For Directing Pancreatic Lineage Differentiation Of Human Embryonic Stem Cells, Weiwei Wang

Graduate Theses and Dissertations

The potential of human embryonic stem cells (hESCs) to differentiate into insulin producing beta cells offers great hope for cell-based therapy for diabetes treatment. However, in vitro pancreatic differentiation of hESCs remains challenging. In the past decade, most protocols for differentiating pancreatic cells have been focused on the use of signaling molecule cocktails on 2D substrates. Studies on embryonic development biology strongly suggest that extracellular matrix (ECM) plays a critical role on hESCs behavior. In this work, we first established a 3D collagen scaffold culture system for hESCs differentiating into definitive endoderm (DE), which is the first and most important …

B. R. Wells Arkansas Rice Research Studies 2013, R. J. Norman, K.A. K. Moldenhauer

Arkansas Agricultural Experiment Station Research Series

No abstract provided.

A Novel Cell Based Assay For Mmp Inhibitor Screening, Pantrika Krisanarungson

Graduate Theses and Dissertations

Up to date, a plethora of protein based materials are used as implants to stimulate tissue regeneration or fillers to alleviate tissue or organ impairment. This includes glottal insufficiency, urinary bladder incontinence and especially in cosmetic industrial to improve facial contour. Once in vivo, protein-based materials are decomposed by cell secreted matrix metalloproteinases (MMP) and lose their volume within months. By introducing MMP inhibitor (MMPI), the extent of material degradation over time may be reduced. In this dissertation, the development of cell-based assay capable of identifying MMPI candidates for protein-based implant lifetime prolongation is described. To visualize the degradation, DQ-gelatin, …

Modified-Electrodes For Redox-Magnetohydrodynamic (Mhd) Pumping For Microfluidic Applications, Christena Kayl Nash

Graduate Theses and Dissertations

A new microfluidic pumping and stirring technique was demonstrated for lab-on-a-chip applications. Microfluidics was accomplished via redox-MHD, which takes advantage of a body force (F_B) that is generated when there is a net movement of ions in solution (j) in the presence of a perpendicular magnetic field (B), according to the equation F_B = j×B. In this work the movement of ions in solution was generated using electrodes modified with the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) rather than a redox species in solution, which can interfere with analyte detection and with biological species. …

Experimental Terahertz Imaging And Spectroscopy Of Ex-Vivo Breast Cancer Tissue, Tyler C. Bowman

Graduate Theses and Dissertations

This thesis presents experimental results of terahertz imaging and spectroscopy techniques to analyze excised breast cancer tissue. The pulsed terahertz system at the University of Arkansas was used to assess formalin-fixed, paraffin-embedded breast cancer tissue obtained from 22, 40, and 46 year old patients. The tissue for this research was sliced to relatively thin sections of 10 μm thick and mounted on glass slides. Terahertz reflection time and frequency domain images of the breast cancer tissue were then obtained and compared to histopathology slides from the same patient. Results showed good correlation between the reflection images and histopathology slides for …

Still Circling The Sun, Stefan Rafael Delagarza

Graduate Theses and Dissertations

This work is a collection of traditional and experimental short stories that explore dynamic human relationships in a variety of settings: a bunker, a beach, and a family home, to name a few. Each character is on a journey to find deeper meaning in his or her life, and oftentimes, this means finding a path to forgiveness.

Effects Of Parental Modeling On The Development Of Panic-Relevant Escape And Avoidance Among Adolescents: An Experimental Study Using A Biological Challenge Procedure, Liviu Bunaciu

Graduate Theses and Dissertations

Escape and avoidance behaviors play a prominent role in the maintenance of panic-spectrum difficulties and may also be implicated in the development of such problems. Although the current state of the literature regarding the etiology of these emotion-regulation strategies is relatively underdeveloped, it appears that learning experiences involving parental modeling of such behaviors may be instrumental in the development of panic-relevant escape and avoidance. Given that no tests of such a conceptualization exist at this time, the current study proposed an initial experimental examination of whether parental modeling of defensive reactivity during a well-established biological challenge could impact panic-relevant escape …

Academic Clustering Of Student-Athletes: A Case Study Of Football And Basketball Programs, Matthew Brett Rowland

Graduate Theses and Dissertations

This study explores the topic of academic clustering within the football and men's and women's basketball teams at the University of Arkansas. Given the prominence of collegiate sport in America, this paper examines a relatively understudied topic regarding student-athletes and education. Using a mixed methods approach, the topic of academic clustering is analyzed statistically, as well as through in-depth interviews with student-athletes and academic advisors in the athletic department. Statistical analysis shows significant over- and under-representation of student-athletes in certain University colleges (e.g., Fulbright College of Arts and Sciences, Walton College of Business, and College of Engineering), the presence of …

Identification And Development Of The Support Needs In Nematology For Arkansas Cooperative Extension Personnel, Mia Gentry

Graduate Theses and Dissertations

County extension agents are vital to the land-grant university system and are responsible for transferring current, research-based knowledge from the university to the community. In-service training allows agents the means to maintain a current, sound knowledge base. Needs identified by leading nematologists led the researcher of this study to assess if nematology education was a topic that warranted in-service training development for Arkansas Cooperative Extension Service (CES) agents. The researcher also assessed agents' comfort level with job related technology. Of the respondents, 67% identified general knowledge of plant parasitic nematodes necessary to meet the needs of their clientele. Findings from …

Balance And Power In Older Adults With And Without A History Of Falls, Stephanie Michelle Gray

Graduate Theses and Dissertations

The purpose of this study was to observe the differences between power and balance in older adults over the age of 65 with and without falls. A total of 62 community dwelling older adults between the ages of 65 and 92 participated in the study. Two groups consisted of 25 fallers and 37 non-fallers. No statistical differences were found between groups on age, height, weight, or BMI. Testing included the Berg Balance Scale (BBS) to test balance, the Tendo Weightlifting Analyzer (TWA) during a sit-to-stand to test lower body power, and the Physical Activity Scale for the Elderly (PASE) to …

Improving Golf Putt Performance With Statistical Learning Of Eeg Signals, Qing Guo

Graduate Theses and Dissertations

In this thesis, a machine learning based method is proposed to predict the putt outcomes of golfers based on their electroencephalogram (EEG) data. The method can be used as a core building block of a brain-computer interface, which is designed to provide guidance to golf players based on their EEG patterns. The proposed method includes three steps. First, multi-channel 1-second EEG trials were extracted during golfers' preparation of putting. Second, different features are calculated such as correlation coefficient, power spectrum density and coherence, which are used as features for the classification algorithm. To predict golfers' performance, the support vector machine …

Application Of Membrane Processes For Concentration And Separation Of Sugar Streams In Biofuel Production, Mohammadmahdi Malmali

Graduate Theses and Dissertations

The overall objective of this study was identification and development of a sugar concentration/separation membrane filtration unit to improve the bioconversion of lignocellulosic biomass into chemicals and fuels. This thesis is divided into three main parts. The first part is about our studies on the use of nanofiltration membranes for concentration of sugars in a lignocellulosic biomass hydrolysate. In addition, the feasibility of simultaneous removal of acetic acid, 5-(hydroxymethyl)furfural and furfural from the hydrolysate has also been investigated. The results obtained indicate that both concentration of sugars and removal of hydrolysis degradation products is feasible. However, careful selection of the …

Self-Assembly Of Gold Nanosphere Dimers By Inertial Force, George Andrew Christopher Sakhel

Graduate Theses and Dissertations

The morphology and composition of a nanoparticle (NP) play a critical role in determining the NP's properties and function. To date, researchers have created a myriad of NPs of different shapes, sizes, and compositions with interesting attributes and applications ushering a revolution in medicine, electronics, microscopy, and microfluidics.

In this study, gold (Au) nanosphere dimers (NSDs) have been synthesized through a novel self-assembly method. These particles were created from Au NPs mono-dispersed in aqueous solution via a process of centrifugation and capping agent replacement. Au NSDs consist of two Au NPs combined together with minimal gaps between them. Optical spectral …

Tempo And Mode Of Domestication During The Neolithic Revolution: Evidence From Dental Mesowear And Microwear Of Sheep, Melissa Zolnierz

Graduate Theses and Dissertations

The Neolithic Revolution marked a dramatic change in human subsistence practices. In order to explain this change, we must understand the motive forces behind it. Researchers have proposed many different stimuli, with most theories invoking environmental dynamics, human population density increases beyond environmental carrying capacity, and the natural outgrowth of human and plant/animal interactions. However, unanswered questions remain concerning the mechanics of animal domestication. Traditional studies of changing faunal morphology and skeletal population profiles offer some clues, but such research has had limited success identifying stages intermediate between wild and domesticated forms, which makes it difficult to discern initial attempts …

The Effect Of Leucine Supplementation On Biomarkers Of Mitochondrial Biogenesis And Protein Synthesis In Soleus Muscle Of Rats Fed A High-Fat Diet, Gina Davis

Graduate Theses and Dissertations

Mitochondrial dysfunction is a contributing factor to the advancement of various diseases including obesity, diabetes, and cardiovascular disease. Impairment in mitochondria brings about a diminished mitochondrial number and oxidative capacity. Leucine is known to stimulate muscle protein synthesis through transcription and translation of nuclear DNA leading to increases in mitochondrial biogenesis and fatty acid oxidation. However, the effects of leucine on anabolic factors of the mitochondrial genome, during catabolic conditions are not known. PURPOSE: To determine if leucine supplementation alters the negative effects of a high fat (60%) diet (HFD) on the mitochondrial genome by measuring the gene expression of …

Correlated Response To Selection And Effects Of Pre-Slaughter Environment On Meat Quality In Broilers Divergently Selected For Muscle Color, Isaac David Harford

Graduate Theses and Dissertations

Two broiler lines divergently selected for high (HMC) and low (LMC) muscle lightness (L*) were formed from a random bred control line (RBC). After eight generations of selection, three experimental trials were conducted to investigate the correlated response to selection and effects of pre-slaughter environment on meat quality in all three lines.

In the first experiment, a total of 100 birds from each line were bled for blood chemistry analysis and were evaluated for meat quality the following day. The HMC line had higher fillet drip loss (DL), L*, heterophil to lymphocyte ratio (H:L), and platelet count (Plt), and lower …

Male Privilege, Sexual Double Standard, And Sexual Scripts: College Students' Perceptions And Influences Of Hooking Up, Mary Ellen Hunt

Graduate Theses and Dissertations

Approximately three-fourths of young adults in college hook up at least once by their senior year (i.e., engage in a casual sexual encounter outside the context of a committed relationship). There are important gender differences which may inform how men and women conceptualize hooking up. Men and women may have different predictors of interest, expectations of sex, or attitudes toward sex. These gender differences are likely culturally constructed by the sexual double standard and traditional sexual scripts which project men to be the aggressive sexual initiators who want sex all the time, and women to be passive gatekeepers who desire …

Lab-Scale Experiment For Assessing The Effect Of Resuspension And Oxygenation On Sediment Oxygen Demand, Grace Richardson

Graduate Theses and Dissertations

This study examined the effects of resuspending lake sediment for different time periods in a lab-scale tank under both oxic and anoxic conditions on sediment oxygen demand (SOD) and other related sediment properties. This lab-scale study was conducted as a first step to determine if a proposed method for reducing SOD by treating sediments in lakes and reservoirs is feasible. SOD is a critical process responsible for the formation of anoxic hypolimnia in lakes and reservoirs. A reduction in SOD may delay or eliminate the onset of anoxia in the hypolimnia, preventing adverse ecosystem effects and improving water quality and …

Transitioning To Writing About Writing: A Consideration Of The Metawriting Teaching Approach At The University Of Arkansas, Katie Michelle Smith

Graduate Theses and Dissertations

This thesis uses case studies of six Teaching Assistants and Instructors to analyze the curricular and pedagogical shift from a writing-through-literature model to the Composition II course to a metawriting approach during the 2014 spring semester at the University of Arkansas. The administrative decision from the Program in Rhetoric and Composition to make this transition came in response to the 2007 article by Elizabeth Wardle and Douglas Downs in College Composition and Communication outlining a "Writing about Writing" approach to teaching composition.

Characterizing Nanoparticle Size By Dynamic Light Scattering Technique (Dls), Marzia Zaman

Graduate Theses and Dissertations

The Dynamic Light Scattering Technique was used to determine the size, shape and diffusion coefficient of nanoparticle. The intensity auto correlation functions of light scattered by particles in a solution were measured by using a photomultiplier tube and analyzed to get the relaxation rates for decay of intensity correlations, which correspond to the diffusion constants pertaining to the motion of the particle. In the case of nanorods there are two types of motion - translational and rotational. By dis-entangling the relaxation rates, corresponding to these two types of motion, the shape and size of nanoparticle could be characterized. These experiments, …

Effects Of Large Scale Growing Season Prescribed Burns On Movement, Habitat Use, Productivity, And Survival Of Female Wild Turkey On The White Rock Ecosystem Restoration Project Of The Ozark-St. Francis National Forest, Henry Tyler Pittman

Graduate Theses and Dissertations

Restoration of woodland and savanna ecosystems has become a common management strategy in the Central Hardwoods region. Over the past two decades forest managers have implemented woodland and savanna restoration at the landscape level (≥10,000 ha), especially using early growing season prescribed fire. The implementation of the restoration strategy has coincided with declines of Eastern Wild Turkey (Meleagris gallopavo silvestris) in many treated areas causing concern that early growing season prescribed fire was impacting wild turkey. We initiated our study to examine the effect of woodland and savanna restoration on the ecology and habitat of wild turkey in the Ozark …

Impedance Biosensors For The Rapid Detection Of Viral And Bacterial Pathogens Using Avian Influenza Virus Subtypes H5n1 And H7n2 And Escherichia Coli O157:H7 As Model Targets, Jacob David Lum

Graduate Theses and Dissertations

This research investigated impedance biosensors for the rapid detection of viral and bacterial pathogens using avian influenza virus (AIV) subtypes H5N1 and H7N2 and Escherichia coli O157:H7 as the model targets, which were chosen due to their impact on the agricultural and food industries. For the detection of AIV H7N2, a single stranded DNA aptamer was selected using systematic evolution of ligands by exponential enrichment (SELEX). The selected aptamer and a previously selected aptamer against AIV H5N1 were used in a microfluidics chip with an embedded interdigitated array microelectrode to fabricate an impedance biosensor for specific detection of AIV H7N2 …

The Influence Of Literacy On The Lives Of Twentieth Century Southern Female Minority Figures, Laura Leighann Dicks

Graduate Theses and Dissertations

The American South has long been a region associated with myth and fantasy; in popular culture especially, the region is consistently tied to skewed notions of the antebellum South that include images of large plantation homes, women in hoop skirts, and magnolia trees that manifest in television and film representations such as Gone With the Wind (1939). Juxtaposed with these idealized, mythic images is the hillbilly trope, reinforced by radio shows such as Lum and Abner, and films such as Scatterbrain (1940). Out of this idea comes the southern illiteracy stereotype, which suggests that southerners are collectively unconcerned with education …

Facing The Wreck: Death, Optimism, And The Fragmented Form, Rachael Marie Schaffner

Graduate Theses and Dissertations

Walter Benjamin described history as a winged angel who faces backwards, staring perpetually into the past as the violent winds of destiny carry him into the future (Illuminations). Despite a western, post-enlightenment myth of eternal progress, the wreckage of human contributions to history is clearly evident in our 21st-century understanding of anthropogenic impact on global ecology. In the context of these ecological crises (and the resulting political and economic questions), postmodern novels reveal a powerful ability to imagine different ways of living and interacting with the world. This thesis traces the relationship between fragmentation, death, and liminal experiences …

Nanofabrication Of Metallic Nanostructures And Integration With Light Detection Devices, Liang Huang

Graduate Theses and Dissertations

Metallic nanostructures have been investigated with various applications especially for integration with light detection devices. The incident light can be manipulated by those nanostructures to enhance light absorption therefor improve device performance. However, previous studies focused on optical design. The electrical properties of these integrated light detection devices have not been fully considered. The photon generated carriers transport and collection are critical for light detection devices as well. An optimized device platform considering from both the optical and electrical aspects to fully utilize these nanostructures is highly desired for future light detection devices.

This dissertation targeted on three objectives, beginning …

Nitrogen Management Practices And Colored Plastic Mulch Films Affecting Spider Mites And Aphids On Winter Strawberry In A High Tunnel, Kevin Philip Durden

Graduate Theses and Dissertations

Off season high tunnel strawberry production has the potential to augment income for Arkansas fruit growers during an unproductive time of the year, however management guidelines do not exist. At the University of Arkansas Agricultural Research and Extension Center in Fayetteville, AR studies were conducted to evaluate the effects of four nitrogen (46-0-0 urea fertilizer) fertigation rates (0.75, 0.50, 0.25, 0.0 kg N/day/ha) and red or black colored plastic mulch films on densities of twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), numbers of parasitized cotton aphids, and fruit yield weight. Foliar and …

Ethnocultural Differences In Motivations For Sex, Arthur Robert Andrews Iii

Graduate Theses and Dissertations

Motivations for sex are numerous and varied (Browning, 2004; Meston & Buss, 2007). Using exploratory factor analytic methods, 21 theoretically distinct motivations have been proposed (Browning, 2004; Meston & Buss, 2007). A comprehensive number of motivations for sex has yet to be examined with confirmatory techniques. Theoretical work related to the treatment of sexual dysfunction has suggested that motivations focused on individual and partner pleasure would positively relate to sexual functioning (e.g., Leiblum & Rosen, 1992). Motivations for sex also appear to vary as a function of ethnocultural factors, as some motivations have only been uncovered utilizing qualitative methods with …

Animal Science E-Newsletter, July 2014, University Of Arkansas, Fayetteville. Department Of Animal Sciences

Animal Science e-Newsletter

No abstract provided.

Annual Report, 2013-2014, University Of Arkansas, Fayetteville. Office Of The Vice Provost For Research And Economic Development

Research and Innovation Annual Report

No abstract provided.

Performance Of All Student Subgroups In Arkansas: Moving Beyond Achievement Gaps, Sarah M. Burks, Gary W. Ritter

Arkansas Education Reports

The 2013-14 school year marks ten years since the Arkansas General Assembly passed legislation to construct a new K-12 funding system in response to a 2002 Arkansas Supreme Court ruling in the decades-long court case, Lake View School District No. 25 v. Huckabee. The General Assembly established a foundation formula to provide adequate funding to districts across the state and created categorical funding to provide additional equity funding to districts based on need. In doing so, the state provides additional funding to districts based on the number of students that are English Language Learners, in alternative learning environments, or from …