Digital Commons Network^™

Mr-Compatible Electrophysiology Recording System For Multimodal Imaging, Nishant B. Barbaria

Open Access Theses

Simultaneous acquisition of functional magnetic resonance imaging (fMRI) and electrophysiological recordings is an emerging multimodal neuroimaging strategy for studying brain functions. However, the strong magnetic field generated during fMRI greatly degrades the electrophysiological signal quality during simultaneous acquisition. Here, I developed a low powered, miniaturized, system – “ECHO” which delivers a hardware and software solution to overcome the challenges presented by multimodal imaging. The device monitors fluctuations in electromagnetic field during fMRI and synchronizes amplification and sampling of electrophysiological signals to minimize effects of gradient and RF artifacts (electromagnetic artifacts). Furthermore, I introduced a concept of wirelessly transmitting recorded data …

High Resolution Temperature Measurement Using Ters, Qian Cao

Open Access Theses

Heat is a functional importance in nanoscale devices. It will affect the function and performance of the device if not distributed properly. Since the development of nano-science, various studies have been issued on nanoscale temperature mapping utilizing a variety of techniques. Among them, optical methods are preferred due to its noninvasive characteristic. Especially, Tip Enhanced Raman Spectroscopy (TERS) performs as a tool with high spatial resolution in temperature mapping.

In this work, a homemade TERS system based on AFM is utilized as the tool for nanoscale temperature mapping. Bismuth thin film is used as nanoscale thermometer due to the characteristic …

Modeling And Parameter Characterization Of A Betavoltaic Cell, Darrell S. Cheu

Open Access Theses

Betavoltaic cells are a type of nuclear battery where kinetic energy from beta particles are converted into electricity. The goal of this research is to evaluate betavoltaic cell electrical performance and predict its response to temperature changes for potential implementation. To achieve this goal, three tasks were performed: betavoltaic cells were electrically characterized under temperature, critical betavoltaic semiconductor parameters were experimentally determined, and the Shockley-Diode model was used to predict electrical performance and compared to experimental results.

Betavoltaic cells were evaluated from -30◦Cto70◦C. I-V curves were gathered at each temperature step in order to determine open circuit voltage and short …

Chocolate Almond Milk Consumption Changes Salivaryproline-Rich Protein Expression, Whichalterastringencyandbitterness, Ciera Crawford

Open Access Theses

In this work we analyze how humans experience sensations from polyphenols, focusing particularly on chocolate flavonoids. First, we investigated how people use terms to describe the “astringent” sensation of these compounds, determining that the words “dry, rough” may be a feasible alternative to the poorer understood term “astringent.” Next, we investigated how human salivary proteomes may influence the sensations of chocolate flavonoids, and whether those proteomes change after exposure to the compounds in chocolate milk for a week. In this larger six-week study design, subjects alternated each week between consuming a low polyphenol diet and consuming one of three different …

Hyperspectral Modeling Of Relative Water Content And Nitrogen Content In Sorghum And Maize, Valerie Cross

Open Access Theses

Sorghum and maize are two of the most important cereal grains worldwide. They are important industrially, and also serve as staple crops for millions of people across the world. With climate change, increasing frequencies of droughts, and crops being planted on more marginal land, it is important to breed sorghum and maize cultivars that are tolerant to drought and low fertility soils. However, one of the largest constraints to the breeding process is the cycle time between cultivar development and release. Early evaluation of cultivars with increased the ability to maintain water status under drought and increases nitrogen contents under …

Biodynamic Imaging System: A Novel, Noninvasive Method For Assessing Embryo Viability., Natalie Ehmke

Open Access Theses

In vitro embryo production is the foundation of most assisted reproductive technologies, yet efficiency of these technologies is relatively low due to the lack of a reliable method for measuring embryo viability. Current methods to evaluate the viability of in vitro derived embryos are invasive or expensive to perform. In order to create a reliable system to assess the developmental potential of the embryo, a novel optical approach known as BioDynamic Imaging (BDI) has been proposed for application. BDI is able to measure dynamic processes inside an embryo encompassing a broad range of motions that relate directly to functional developmental …

Electrostatic Regulation Of Phospholipase C Beta Enzymes, Candi Michelle Esquina

Open Access Theses

Phospholipase C (PLC) proteins cleave phosphatidylinositol lipids from cellular membranes to produce the second messengers inositol triphosphate (IP3) and diacylglycerol (DAG). The PLCb subfamily is among the best characterized of the PLC enzymes and is crucial for normal cardiovascular function. Under basal conditions, PLCb has low activity and is partitioned between the plasma membrane and the cytoplasm. However, it is unclear how this low activity state is maintained from a molecular standpoint. One known autoinhibitory element is the X–Y linker, a loop within the catalytic domain that forms a lid over the active site and which is displaced through interfacial …

Parental Restrictive Feeding With Latino Adolescents: Examining The Role Of Adolescent Self-Regulation In Associations With Body Mass Index, Carly Danae Evich

Open Access Theses

Latino adolescents in the U.S. are disproportionately affected by obesity compared to adolescents of other racial and ethnic backgrounds. Previous studies have suggested that parental restrictive feeding may serve as a modifiable risk factor. However, given that obesity in youth often develops as a function of a child’s susceptibility for weight gain interacting with their environment, the suggested negative effects of parental restrictive feeding may not generalize across all Latino adolescents. One marker of susceptibility for weight gain in youth is poor self-regulation, which can lead to reliance on others to help regulate eating behavior. However, the potential for self-regulation …

Genetics And Genomics Of Golden Eagle Populations With Contrasting Demographic Histories, Nadia B. Fernandez

Open Access Theses

Most species are constrained by geographic barriers to dispersal and geneflow, and such limitations have demographic and genetic consequences. We tested whether a highly vagile bird of prey, the golden eagle (GOEA; Aquila chrysaetos), exhibits disparate genetic signatures among island (Channel Islands, California, USA), peninsular (Baja California Peninsular region, USA) and mainland (California, USA) regions given the contrasting demography and phylogeography among regions. We utilized a SNP assay to estimate heterozygosity, inbreeding coefficients, and the effective population sizes (Ne) of GOEAs. In addition, we sequenced six GOEA genomes to obtain comprehensive measures of homozygosity (i.e., runs of homozygosity, ROHs) burden …

Understanding The Collaboration Difficulties Between Ux Designers And Developers In Agile Environments, Yun-Han Huang

Open Access Theses

With the growing number of UX designers in tech companies in the U.S., the collaboration between UX designers and developers in Agile environments has become a new challenge in the industry. This research study aims to understand the collaboration difficulties between UX designers and developers in Agile environments and further provides insights from the results. The research method was semi-structured interview. A total of five professional UX designers and five professional developers in the industry were interviewed about topics surrounding their collaboration difficulties. The results indicated that UX designers integrating in Agile environments and factors related of organizational context are …

Phosphorus Sorption In Drainage Channel-Floodplain Systems In Agricultural Watersheds, Alexander N. Johnson

Open Access Theses

The two-stage channel is an in-stream conservation practice that creates inset floodplains in agricultural drainage channels and stabilizes streambanks. Inset floodplains are excavated adjacent to the channel, hydrologically reconnecting it to the main channel and tripling the reactive surface area during high flow events. It is uncertain what effect these channel designs have on complex phosphorus (P) dynamics in the stream and in the floodplain, both during baseflow and when channels are flooded. In order to evaluate these practices as a P management strategy, we took soil and water samples from streambed sediments and floodplain soils in 10 two-stage channels …

Conditioned Medium From Dysfunctional Endothelial Cells Negatively Regulates Satellite Cell Expansion And Differentiation, Christopher Kargl

Open Access Theses

Dysfunction of the endothelial lining of the cardiovascular system is a hallmark symptom of both cardiovascular disease (CVD) and type II diabetes mellitus (T2DM). The dysfunctional endothelial cell phenotype is characterized by an increase in production and release of inflammatory cytokines and reactive oxygen species (ROS) and a decrease in nitric oxide (NO) and growth factor secretion. Evidence has emerged showing a close relationship between endothelial cells and skeletal muscle satellite/progenitor cells. Skeletal muscle cell growth and differentiation are impaired in oxidative environments and many endothelial dysfunction-related diseases. The purpose of the current study is to determine the impact that …

Dielectrically-Accurate Tissue Simulating Materials For A Heterogeneous Breast Mri Phantom, Liesl A. Krause

Open Access Theses

Phantoms, which are non-biological test objects, are used to validate a variety of biomedical imaging modalities for accuracy and safety. In MRI, phantoms can be used, specifically, to test safety with regards to SAR and RF heating. This is of particular importance when developing new imaging protocols related to a specific anatomy, MRI use, or other software or hardware updates. Discussed in this thesis is the creation of an anatomically accurate breast phantom for safety testing before use of novel MRI protocols for breast cancer diagnostic imaging. Previous MRI breast phantoms are either homogeneous or have barriers between tissue types, …

Controlled Drainage: Assessment Of Yield Impacts And Education Effectiveness, Amanda Locker

Open Access Theses

Controlled drainage is the practice of using a water control structure to hold water in agricultural fields during periods when drainage is unnecessary. The use of this practice may increase crop yields compared to subsurface drainage because during the growing season controlled drainage can capture water from precipitation, and raise the water table for crop use. Results from published studies of controlled drainage impacts on crop yields have been mixed, and the effects of field characteristics and annual weather variation on these impacts are not well understood. For widespread adoption of controlled drainage, more information on how controlled drainage impacts …

Modeling, Simulation, And Design Of A Radial Piston Digital Displacement Unit, James R. Marschand

Open Access Theses

State of the art variable displacement pumps experience a reduction in efficiency when operating at low displacements. Digital pumps using high speed on/off valves to control fluid entering and leaving the displacement chamber can increase efficiency by eliminating the leakage and friction associated with the port plate and swash plate. Because the displacement chamber is only pressurized during a portion of the piston stroke, leakages scale with displacement which increases efficiency of these units. The largest increase in efficiency comes at low displacements creating a more efficient pump across the entire operating range. Partial displacement can be achieved using four …

Psychophysiological Correlates Of Childhood Maltreatment And Physical Aggression Perpetration, Andrea Massa

Open Access Theses

Objective: Trauma exposure and symptoms of posttraumatic stress disorder (PTSD) have been consistently linked with aggression perpetration in past research. One theory that has been used to help explain the association between trauma and aggression is the “survival mode” theory, which proposes that traumatized individuals develop an overactive threat detection system, which leads to a greater propensity for anger and aggression. The purpose of the current study was to empirically test the survival mode theory of aggression using a novel methodology. Method: Participants in the current study included 20 undergraduate students from a large university. Participants completed self-report measures of …

Something Fishy? Uncovering Patterns Of Genetic Diversity And The Evolution Of Resistance In Fish Populations, Alexander S. Martinez

Open Access Theses

Chapter 1 Abstract Populations of fishes are increasingly threatened by over-exploitation, pollution, habitat destruction, and climate change. In order to better understand the factors that can explain the amount of genetic diversity in wild populations of fishes, we collected estimates of genetic diversity (mean heterozygosity and mean rarefied number of alleles per locus) along with habitat associations, conservation status, and life history information for 463 fish species. We ran a series of phylogenetic generalized least squares (PGLS) models to determine which factors influence genetic diversity in fishes after accounting for shared evolutionary history among related taxa. We found that marine …

Forest Ecosystem Response To Hemlock Woolly Adelgid (Adelges Tsugae) In The Southern Appalachian Mountains, Meghan L. Mulroy

Open Access Theses

The forests of eastern North America are faced with the loss of Tsuga canadensis (eastern hemlock) as the introduction of Adelges tsugae (hemlock woolly adelgid, HWA) an invasive insect native to Japan, has resulted in widespread T. canadensis mortality. Tsuga canadensis ranges from the southern Appalachian Mountains to the Great Lakes and into Canada. The dense canopies of T. canadensis create a cool, damp microclimate, and these conditions, combined with the tannin chemistry and nutrient poor litter of the species, slows decomposition, creating acidic nutrient-poor soils. As a result, understories under T. canadensis trees are typically species poor. Due to …

Towards Highly Sensitive Multi-Analyte Micro-Biosensor Arrays For In Vitro Sensing, James K. Nolan

Open Access Theses

Cells and tissues produce many micron-scale extracellular chemical gradients and fluxes due to metabolism and for communication [1, 2]. These gradients and fluxes have an important role in physiology and pathology. Highly sensitive multi-analyte micro-biosensor arrays would be useful tools for simultaneously measuring the gradients and fluxes of many molecules from cells cultures in vitro. To this end, we have investigated (1) a practical means to functionalize MEAs with two or more enzymes, (2) maximizing the effective surface area of Pt-black-modified biosensor, comparing it to other nanomaterials, (3) the nature of electron transfer between glucose oxidase and single-walled carbon nanotubes, …

Potential Of Biochar To Mitigate The Effects Of Increased Precipitation Variability On Soil Greenhouse Gas Emissions And Soybean Growth, Akane Ota

Open Access Theses

Precipitation variability has been increasing due to climate change, characterized by more frequent heavy rainfalls and more prolonged drought. The projected continuation of this trend in precipitation will likely alter soil greenhouse gas (GHG) fluxes and reduce plant growth. These impacts could be ameliorated by biochar addition in soil. Biochar has been shown to suppress soil GHG fluxes by altering microbial activity or substrate availability, and enhance plant growth by improving soil conditions. However, there have been no biochar studies to date under more variable precipitation conditions. I studied the effects of biochar on soil GHG fluxes and soybean (Glycine …

Improving Fret Relay Mechanism For Redox Dynamics In Live Cells, Jake Norley

Open Access Theses

Reactive oxygen species (ROS) have an important role with regards to intracellular signaling throughout the body. Levels of ROS fluctuate dynamically with differing sources of ROS as well as antioxidant mechanisms to regulate oxidative stress, cell to cell signaling, and cellular metabolism. In many cases, localized redox dynamics have not been elucidated due to a lack of tools available to study oxidative fluctuations localized to different compartments of ROS generation within cells. Previously, our lab reported the development of a new family of genetically encoded fluorescent protein redox biosensors. They utilize the ratiometric properties of roGFP2 and extend its fluorescence …

Low-Cost Grain Moisture Meter System Networked To Smartphones, Marisol Pantoja Otero

Open Access Theses

Accurate moisture content measurement is one of the key quality factors listed in grain trade. It is important in determining whether a crop has been dried properly for safe storage and marketing, and it is used by buyers and sellers of grain to estimate the value of the commodity. Unfortunately, many farmers and grain originators in developing countries cannot afford to buy moisture meters and utilize them to routinely determine whether their crops are dried for safe storage, and thus incur huge losses along the value chain. Additionally, farmers are at a disadvantage in trading to high-ended markets, which have …

Genetic Analysis Of Carotenoid Content In Expired Plant Variety Protected Maize (Zea Mays L.) Inbreds, Samuel T. Prather

Open Access Theses

Lutein and zeaxanthin are the only carotenoids preferentially accumulated in the macular region of the eye. Studies have associated reduced risk of age-related macular degeneration with accumulation of lutein and zeaxanthin. Both lutein and zeaxanthin carotenoids can not be synthesized de-novo by humans and must be obtained from dietary sources. In adults over the age of 65 within the developed world, age-related macular degeneration is the leading cause of blindness. Given the prevalence of age-related macular degeneration in developed regions of the world such as the United States, and the expected increase in the human population over 65 years of …

Disney Minority Heroines: A Rhetorical Analysis Of Race, Gender, And American Politics, Brooklyn Russell

Open Access Theses

The Walt Disney Corporation has provided family-centered entertainment, for decades, in the form of animated films, beginning with the adaptation of Snow White and the Seven Dwarfs (1937). Since then, and succeeding the death of its patriarch in 1966, the Disney Corporation has upheld the legacy of producing films that continue to captivate children through historical, cultural, and rhetorical approaches. However, as generations have passed, Disney heroines have changed and so has their strategies for accomplishing their goals. For decades, Disney has produced similar plot stories using the same character profiles as well: a girl, more often than not living …

Bistable Snapping Structures With Spatially Tailored Deformations Via Distributed Pre- Strain, Katherine S. Riley

Open Access Theses

Materials capable of exhibiting inherent morphing are rare and typically reliant on chemical properties. The resulting diffusion-driven shape adaptability is slow and limited to specific environmental conditions. In contrast, natural composites, such as those found in carnivorous plants, have evolved hierarchical architectures displaying remarkably fast adaptation in response to environmental stimuli. Whereas pre-stress in synthetic structures has conventionally been limited to uniform straight lines and rectilinear geometries, here we present two strategies to achieve spatially distributed pre-stress fields.

The first approach entails the use of magnetically responsive aluminum oxide platelets as reinforcements in an epoxy matrix to create bilayer composite …

Functionalization Of Hyaluronic Acid Hydrogels With Ecm-Derived Peptides To Control Myoblast Behavior, Juan Martin Silva Garcia

Open Access Theses

Volumetric muscle loss (VML) occurs when skeletal muscle injury is too large for the body’s self-regenerative capabilities. As a consequence, fibrotic tissue fills the void, which reduces muscle functionality and limb movement. In the military, VML occurs mainly through explosions which represent more than 70% of total war injuries. Otherwise, the most common causes are traumatic accidents, tumor ablation, and musculoskeletal diseases.

Although a wide variety of natural and synthetic scaffolds have been studied with the purpose of providing the appropriate structural support, to date no scaffold has been able to significantly restore muscle functionality after VML. Satellite cells, adult …

Physiological Changes In Hippocampal Ca3-Ca1 Network Following Pilocarpine Induced Status Epilepticus, Alexandra L. Sommer

Open Access Theses

Status Epilepticus has been shown to increase the risk of developing epilepsy later in life. Anatomical changes such as dendritic instability and reduction in neurotransmitter associated vesicles have been found within the hippocampus. In this study, local field potential recordings in hippocampal slices were measured to determine how the anatomical variation between control and status epilepticus induced animals correlated to function changes in synaptic efficacy and plasticity. Rats and mice induced with status epilepticus were found to have decreased synaptic efficacy, but appeared to demonstrate varying plasticity compensation at different stimulation intensities.

Detection Of Arsenic In Skin In Vivo Using Portable X-Ray Fluorescence (Pxrf) Device, Kevinraj N. Sukumar

Open Access Theses

Arsenic is an element that is highly toxic in its inorganic form. It is widely distributed especially in water that becomes a primary source of exposure for human consumption. Chronic exposure can cause a variety of diseases such as lung cancer, bladder cancer, skin cancer, vascular diseases, and diabetes mellitus. Biomarkers for arsenic exposure are tissues that contain keratin such as hair, nails, and skin. Skin is an ideal biomarker due to its cumulative property that provides information about the individual long-term exposure to arsenic. Hence, a method for measuring arsenic levels in vivo will be useful to study the …

Impacts Of Roads On Non-Native Plant Invasions Into U.S. Forests Under Different Land-Use And Ecoregion Settings, Benjamin S. Taylor

Open Access Theses

Plant invasions can often be attributed to human influences such as roadways and land-uses. It is not clear if roads and land use have a combined influence that can exacerbate plant invasions into forests. Additionally, variation in invasion patterns among forest regions could be better explained by potentially differing influences from roads and land-use. I hypothesized that roads aid plant invasions into forests by allowing invasive plants to establish along adjacent roadsides. Additionally, impacts of land use can exacerbate the road effects (i.e., number of invasive plant species & distance of invasive plants from a road). Here, using data from …

Restoring Joint Lubrication: The Development Of A Biomimetic Lubricin Peptidoglycan To Reduce Friction At The Articular Cartilage Surface, Celina M. Twitchell

Open Access Theses

Osteoarthritis (OA) is a painful and debilitating disease affecting 27 million people nationwide and is often characterized by the degradation of articular cartilage. The loss of lubrication in synovial joints is a major contributor to cartilage damage, and damage can be prevented if proper lubrication is restored through supplemental lubricant treatments. Hyaluronic acid (HA) injections are on the market today, but there is little clinical evidence to support that these products are effective in treating the long-term effects of osteoarthritis. Lubricin, a lubricating proteoglycan found in the human synovial fluid, has become a potential alternative to HA injections. Overall, lubricin …