Discrete Nonlinear Planar Systems And Applications To Biological Population Models, Shushan Lazaryan, Nika Lazaryan, Nika Lazaryan

Theses and Dissertations

We study planar systems of difference equations and applications to biological models of species populations. Central to the analysis of this study is the idea of folding - the method of transforming systems of difference equations into higher order scalar difference equations. Two classes of second order equations are studied: quadratic fractional and exponential.

We investigate the boundedness and persistence of solutions, the global stability of the positive fixed point and the occurrence of periodic solutions of the quadratic rational equations. These results are applied to a class of linear/rational systems that can be transformed into a quadratic fractional equation …

Avatar, Cyborg, Icevorg: Simulacra’S Scion, Guido E. Alvarez

Theses and Dissertations

I propose a theoretical framework that describes how avatars incorporate media as an inherent part of their nature and find a hosting body in cyborgs to navigate and spawn in media. I propose the birth of a new scion that combines avatar, medium and cyborg into a conceptual being that I call “ICEVORG.”

The ICEVORG expands beyond representation into the actual physical world by means of media transgression—more specifically, by the use of the Strange Loop also known as Metalepsis ICEVORG find an effective soil to thrive and interrogate our ideas of reality by means of iteration, expansion, fragmentation and …

Expanding Eco-Visualization: Sculpting Corn Production, Jennifer E. Figg

Theses and Dissertations

This dissertation expands upon the definition of eco-visualization artwork. EV was originally defined in 2006 by Tiffany Holmes as a way to display the real time consumption statistics of key environmental resources for the goal of promoting ecological literacy. I assert that the final forms of EV artworks are not necessarily dependent on technology, and can differ in terms of media used, in that they can be sculptural, video-based, or static two-dimensional forms that communicate interpreted environmental information. There are two main categories of EV: one that is predominantly screen-based and another that employs a variety of modes of representation …

Clinical And Genomic Characterization Of Two Vaginal Megasphaera Species, Abigail L. Glascock

Theses and Dissertations

Two vaginal phylotypes of the genus Megasphaera (phylotype 1 and phylotype 2) were recently associated with bacterial vaginosis (BV), an infection characterized by vaginal dysbiosis. Through an analysis of 16S rRNA profiles of 3,986 women enrolled in the Vaginal Human Microbiome Project, we confirmed that while both phylotypes were associated with BV, Megaspheara phylotype 1 had higher specificity for the condition. Megasphaera phylotype 2 was strongly associated with trichomoniasis. Previous studies have reported that BV-associated organisms are excluded in pregnancy. We observed that Megasphaera phylotype 1, which has been associated with adverse pregnancy outcomes, exhibited a trend of increased prevalence …

The Role Of Α3Β4* Subtype Of Nicotinic Acetylcholine Receptors In Reversing Opioid-Induced Constipation In Mice, Aravind Gade

Theses and Dissertations

Opioids are excellent pain relievers. A major side-effect of chronic opioid treatment is constipation whereas withdrawal following chronic exposure leads to diarrhea and increased gastrointestinal motility. These effects of chronic opioids are mediated by μ-opioid receptors expressed on enteric neurons. Previous studies have shown that chronic opioids enhance sensitivity to nicotine in the gastrointestinal tract. This suggested that prokinetic effects of nicotine mediated through the activation of nicotinic acetylcholine receptors (nAChRs) may be useful in reversing opioid-induced constipation. The goal of this dissertation was to investigate the nAChR subtype expressed on enteric neurons and their role in reversing opioid-induced constipation. …

Meta-Analysis Of Gene Expression Studies, Umaporn Siangphoe

Theses and Dissertations

Combining effect sizes from individual studies using random-effects models are commonly applied in high-dimensional gene expression data. However, unknown study heterogeneity can arise from inconsistency of sample qualities and experimental conditions. High heterogeneity of effect sizes can reduce statistical power of the models. We proposed two new methods for random effects estimation and measurements for model variation and strength of the study heterogeneity. We then developed a statistical technique to test for significance of random effects and identify heterogeneous genes. We also proposed another meta-analytic approach that incorporates informative weights in the random effects meta-analysis models. We compared the proposed …

Using Structural Equation Modeling To Understand The Role Of The Family In Pediatric Asthma Contexts, Nour Al Ghriwati

Theses and Dissertations

Family factors have long been associated with the psychosocial adjustment of children with chronic illnesses, such as asthma (Minuchin, 1975; Rapee, 1997). Research indicates that negative family factors may also contribute to child disease severity, via bio-behavioral mechanisms of effect (Wood et al., 2006); however, these pathways have yet to be examined with a comprehensive focus on more positive family factors. This study sought to examine whether factors such as family cohesion, problem solving abilities, and communication influence asthma symptom severity in children via their effects on child depression and anxiety symptoms. Using structural equation modeling, we identified significant indirect …

Psychoactive Synthetic Cathinones (Or 'Bath Salts'): Investigation Of Mechanisms Of Action, Farhana Sakloth

Theses and Dissertations

Synthetic cathinones represent threatening and high abuse-potential designer drugs. These are analogs of cathinone (the b-keto analog of amphetamine (AMPH)) a naturally occurring stimulant found in the plant Catha Edulis. Methcathinone (MCAT) was the first synthetic analog of cathinone to be identified in 1987 by Glennon and co-workers and it exerted its action primarily through the dopamine transporter (DAT). Most central stimulants exert their action via monomaine transporters by causing either the release (e.g. cathinone analogs such as MCAT) or by preventing the reuptake (e.g. cocaine) of the neurotransmitter dopamine (DA) thus increasing the extracellular synaptosomal concentration of this …

Interaction Between Atm Kinase And P53 In Determining Glioma Radiosensitivity, Syed F. Ahmad

Theses and Dissertations

Glioblastoma multiforme (GBM) is the most common primary brain tumor. Studies have shown that targeting the DNA damage response can sensitize cancer cells to DNA damaging agents. Ataxia telangiectasia mutated (ATM) is involved in signaling DNA double strand breaks. Our group has previously shown that ATM inhibitors (ATMi) sensitize GBM cells and tumors to ionizing radiation. This effect is greater when the tumor suppressor p53 is mutated.

The goals of this work include validation of a new ATM inhibitor, AZ32, and elucidation of how ATMi and p53 status interact to promote cell death after radiation. We propose that ATMi and …

Factors That Influence Breast Cancer Diagnoses In Virginia Women 40-64 Years Old Who Utlized The Every Woman’S Life Program 1998-2012, Melanie C. Dempsey

Theses and Dissertations

This dissertation examines sociodemographic determinants and preventive health behaviors among women 40-64 years of age who participated in the Virginia Department of Health’s Every Woman’s Life breast cancer screening program. Utilizing secondary data, this research sought to explore patterns of breast cancer incidence, mammography screening utilization and sources of health information among low-income women.

The Virginia Department of Health provided a large sample size (N=34,942) on which to perform binary logistic regression analyses. Sociodemographic determinants and preventive health behaviors were analyzed as potential influencing factors in the diagnosis of breast cancer, the stage at the time of diagnosis and source …

Normalizing Tumor Vasculature Using Sepiapterin To Increase Radiosensitivity, Ninu Bruno

Theses and Dissertations

Our studies examine the role of nitric oxide synthase (NOS) in tumor vasculature. NOS is “uncoupled” in tumor cells, resulting in peroxynitrite (ONOO^-) formation in lieu of nitric oxide (NO). NO signaling is critical for vascular function, thus uncoupling of eNOS in endothelial cells may partly explain the poor vasculature found within tumors. NOS can be “recoupled” through Sepiapterin (SP) treatment of tumor cells. We examined whether SP could normalize tumor vasculature, promoting radiosensitivity. Optoacoustic tomography of flank xenografts and spontaneous tumor models demonstrate that SP significantly enhances percent oxyhemoglobin in tumors. Immunohistochemical analysis of SP-treated tumors showed …

The Role Of Psychology In Integrated Primary Care For Complex Patients: Effects On Mental Health, Utilization Of Medical Services, And Physiological Markers Of Health, Danielle C. Worthington

Theses and Dissertations

This study served as an initial evaluation of integrated psychology services within a clinic designed to serve uninsured patients with complex medical concerns and high utilization histories at the Medical College of Virginia in Richmond, Virginia. The current study evaluates patient outcomes, and more specifically, it further quantifies and describes the role that psychologists play in the primary care setting and their impact on utilization of medical care and in improved health outcomes. Additionally, the study evaluates psychologists’ success at treating mental and behavioral health conditions within the primary care model. The present study demonstrates that patients with complex medical …

Nitric Oxide Synthase Activity And Its Modulation In The Treatment Of Colorectal Cancer, Asim Alam

Theses and Dissertations

The American Cancer Society estimates more than 141,000 new cases of and about 50,000 deaths from colorectal cancer every year. Treatment options include surgery, radiation therapy and targeted therapies such as anti-angiogenics. However, no therapies address the key driving factor of colorectal cancer: inflammation. It is well known that chronic inflammatory conditions such as Crohn’s Disease, ulcerative colitis, diabetes, obesity and cigarette smoking all elevate the risk of developing colorectal cancer. One of the hallmarks of chronic inflammation is the elevated levels of reactive oxygen/nitrogen species (ROS/RNS). A primary source of these ROS/RNS is uncoupled Nitric Oxide Synthase (NOS). Under …

Integrated Nanoscale Imaging And Spatial Recognition Of Biomolecules On Surfaces, Congzhou Wang

Theses and Dissertations

Biomolecules on cell surfaces play critical roles in diverse biological and physiological processes. However, conventional bulk scale techniques are unable to clarify the density and distribution of specific biomolecules in situ on single, living cell surfaces at the micro or nanoscale. In this work, a single cell analysis technique based on Atomic Force Microscopy (AFM) is developed to spatially identify biomolecules and characterize nanomechanical properties on single cell surfaces. The unique advantage of these AFM-based techniques lies in the ability to operate in situ (in a non-destructive fashion) and in real time, under physiological conditions or controlled micro-environments.

First, AFM-based …

Physicochemical And Structural Analysis Of Polymers As Putative Drugs, Meghan L. Thompson

Theses and Dissertations

Sulfated low molecular weight lignins (LMWLs) have shown good activity as anticoagulants by allosterically inhibiting thrombin, as well as promising agents for treating emphysema through inhibition of elastolysis, oxidation, and inflammation. Sulfated LMWLs are chemo-enzymatically synthesized from starting monomers caffeic, ferulic, and sinapic acid into sulfated dehydropolymers known as CDS, FDS, and SDS. To further the LMWLs’ development as drugs, their structural composition and physicochemical characteristics were defined in this work. The molecular weight distribution profile of the sulfated LMWLs from size exclusion chromatography performed on a high pressure liquid chromatography system (SEC-HPLC) changed from bimodal when no surfactant is …

Measuring The Impact Of Recognized Patient-Centered Medical Homes (Pcmh), Rick Moore

Theses and Dissertations

This dissertation proposal seeks to understand if the increasingnumbers (density) of recognized PCMH practices incommunities affect avoidable hospitalizations related toambulatory care sensitive conditions (ACSC), as measured bythe AHRQ Composite Prevention Quality Indicators (PQI). Theresearch has two purposes: 1. Establish constructs and hypotheses to measurethe effect of the increasing numbers of NCQA-Recognized PCMH practices in communities(counties). 2. Using an outcomes-based measurement approach,investigate the relationship between growingdensities of NCQA-Recognized PCMH practicedoctors among all primary care doctors (PCD) ina community and the associated impact on theutilization of inpatient care, specifically related toACSCs, as measured by the AHRQ CompositePQIs.

The research is quasi-experimental in …

Examination Of Basal Neuroendocrine Levels In Oif/Oef/Ond Veterans, Sage E. Hawn

Theses and Dissertations

Abstract

EXAMINATION OF BASAL NEUROENDOCRINE LEVELS IN OIF/OEF/OND VETERANS

By Sage E. Hawn, B.S.

A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University.

Virginia Commonwealth University, 2015.

Major Director: Ananda B. Amstadter, PhD.

Associate Professor

Departments of Psychiatry, Psychology, & Human and Molecular Genetics

High rates of combat exposure exist among veterans of the recent conflicts, and are associated with debilitating mental health conditions, including posttraumatic stress disorder (PTSD). Numerous psychosocial and biologic factors are associated with PTSD, including the HPA-axis. The present study aimed to compare baseline neuroendocrine …

Conduction States Of The Human Dopamine Transporter, Krasnodara Cameron

Theses and Dissertations

Dysregulation of dopaminergic homeostasis has been established as the primary source of numerous neurological disorders including Parkinson’s and drug addiction. A tonic increase of dopamine (DA) in the nucleus accumbens is required for associating everyday events and behaviors with rewards. Yet many addictive exogenous compounds such as amphetamine (AMPH) and cocaine (COC) produce a much greater augmentation of synaptic DA levels that are linked to euphoria and a shift in behavior towards drug seeking. The protein responsible for maintaining extracellular levels of DA is the dopamine transporter (DAT). It is primarily located in the perisynaptic area at terminals of pre-synaptic …

Exploring Dimensions Of Well-Being Among Spouses Of Active-Duty Service Members, Lisa A. Gray

Theses and Dissertations

During an era when the United States has been engaged in the longest waging wars in U.S. history, military families have been exposed to extraordinary amounts of stress and have had to learn to adapt in a culture where repeated deployments, recurrent family separations, and frequent relocations have become the norm. A surge in research in recent years on the families of Service members has brought increased attention to the unique challenges and demands of spouses, raising concerns about how to best meet their needs. Despite the increased attention, few studies have focused on spousal well-being. Acknowledging this lack of …

African American Women’S Perceptions Of Hiv Prevention Communication With Their Reproductive Health Providers, Valerie Burge-Hall

Theses and Dissertations

In spite of a decline in HIV incidence rates among African American women, they still bear the most significant disease burden among U.S. women. Findings from numerous studies indicate probable explanations for the disparity, such as the impact of poverty, limited healthcare access, low literacy, and living in areas with high HIV rates. Additionally, many study results provide insight regarding prevention strategies. However, the aim of this study is to explore African American women’s perceptions regarding what HIV prevention communication, if any, occurred with their reproductive health providers (RHPs). In this study, 20 African American women with unknown HIV status …

Vitamin C: A Potential Regulator Of Inflammatory Response, Bassem M. Mohammed

Theses and Dissertations

Introduction: Neutrophils (PMNs) and Macrophages are the first responders recruited consecutively to the site of injury/inflammation. PMNs’ response/fate as well as macrophage reprogramming ultimately determine the course of resolution of inflammation. Physiologic wound healing has a significant inflammatory component. An exaggerated inflammation however is self-defeating leading to delayed healing. Parenteral vitamin C (VitC) attenuated inflammation in murine sepsis models and in patients with sepsis. However information about the mechanisms by which VitC regulates these events is limited.

Methods: Humanized mice lacking VitC synthesis capability (Gulo^-/-) were used. VitC sufficient and deficient mice were challenged with sterile inflammation, or …

Determinants Of Turnover Intent In Higher Education: The Case Of International And U.S. Faculty, Jaehee Park

Theses and Dissertations

In spite of the increase in the number of the international academic workforce and their potential benefits, international status has been relatively under-studied in Public Management and Higher Education literature in comparison with studies of age, gender, and race. Given these realities, the present study identifies characteristics of internal and external variables that influence international and U.S. faculty turnover intentions in a large public South Eastern research university.

To understand the variations in short-term and long-term turnover levels while controlling for various demographic, structural, and external variables, eight Ordinary Least Square (OLS) regression analysis were performed using turnover intentions as …

Chronic Behavioral And Cognitive Deficits In A Rat Survival Model Of Organophosphate Toxicity, Beverly Huang

Theses and Dissertations

Organophosphates (OPs) are a major class of pesticides and nerve agents that elicit acute toxicity by inhibiting acetylcholinesterase (AChE), the enzyme responsible for the degradation of the neurotransmitter acetylcholine in the central and peripheral nervous systems. Acetylcholine accumulation following extensive AChE inhibition leads to an acute cholinergic syndrome characterized by autonomic dysfunction, involuntary movements, muscle fasciculations, respiratory distress, and seizures. Despite their classification as moderate to highly toxic, OP pesticides are the most widely used class of insecticides in the U.S., and are even more commonly used worldwide. Additionally, there is a growing concern that OP nerve agents could be …

Enhanced Epithelial-To-Mesenchymal Transition Associated With Lysosome Dysfunction In Podocytes: Role Of P62/Sequestosome 1 As A Signaling Hub, Guangbi Li

Theses and Dissertations

Autophagy is of importance in the regulation of cell differentiation and senescence in podocytes, the highly differentiated glomerular epithelial cells. It is possible that derangement of autophagy under different pathological conditions activates or enhances Epithelial-to-Mesenchymal Transition (EMT) in podocytes, resulting in glomerular sclerosis. To test this hypothesis, the present study produced lysosome dysfunction by inhibition of vacuolar- type H⁺-ATPase (V-ATPase) to test whether deficiency of autophagic flux enhances EMT in podocytes. By Western blot analysis, inhibition of lysosome function by V-ATPase inhibitor or its siRNA was found to induce a significantly enhanced EMT in cultured podocytes, as shown …

Peracetic Acid Sterilization Of Electrospun Polycaprolactone Scaffolds, Suyog Yoganarasimha

Theses and Dissertations

Sterilization of tissue engineered scaffolds is an important regulatory issue and is at the heart of patient safety. With the introduction of new biomaterials and micro/nano structured scaffolds, it is critical that the mode of sterilization preserve these built-in features. Conventional sterilization methods are not optimal for engineered polymeric systems and hence alternate systems need to be identified and validated. PCL is polyester with a low melting point (heat labile), susceptible to hydrolysis and is popular in tissue engineering. Electrospinning generates some nanoscale features within the scaffold, the integrity of which can be affected by sterilization method. Chapter 1 explores …

“Frailty, Thy Name Is Woman”: Depictions Of Female Madness, Julianna Little

Theses and Dissertations

Concepts of mental health and normality cannot be understood apart from cultural norms and values. The most significant of cultural constructions that shape our view of madness is gender. Madness has been perceived for centuries metaphorically and symbolically as a feminine illness and continues to be gendered into the twenty-first century. Works of art and literature and psychiatric medicine influence each other as well as our understanding and perception of mental illness. Throughout history, images of mental illness in women send the message that women are weak, dangerous, and require containment. What are the cultural links between femininity and insanity, …

Esthetic Preferences Of Maxillary Incisor Labiolingual Inclination Across Races, Elvi M. Barcoma

Theses and Dissertations

Abstract

ESTHETIC PREFERENCES FOR MAXILLARY INCISOR LABIOLINGUAL INCLINATION ACROSS RACES

by Elvi Marie Barcoma, D.D.S.

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Dentistry at Virginia Commonwealth University

Virginia Commonwealth University, 2015

Major Director: Bhavna Shroff, D.M.D., M.Dent.Sc, Program Director, Orthodontics

Objective: To determine if people of different racial backgrounds prefer different amounts of

maxillary incisor labiolingual inclination from a smiling profile view.

Materials and Methods: An electronic survey was created with smiling profile images of an African-American female and a White female with varying degrees of maxillary incisor labiolingual inclination. …

Restorative Characteristics Of Intrapulpally Cracked Teeth, Charles M. Beavers

Theses and Dissertations

Cracked teeth have long presented a diagnostic challenge. Previous investigators have considered possible predictive factors, many of which revolve around the tooth’s restorative characteristics. Few have investigated the restorative status of teeth with cracks extending into the pulp chamber. The purpose of this investigation was to determine the prevalence of the different types of restorations present in intrapulpally cracked teeth and determine any other restorative factors that may aid in predicting the presence or extent of an intrapulpal crack. Intrapulpally cracked molars requiring endodontic therapy at the VCU Graduate Endodontic Practice were included in this study. For each tooth, the …

In-Vitro Assessment Of A Novel Bracket's Effect On Resistance To Sliding, James Blackburn

Theses and Dissertations

Friction, binding and notching are the factors that contribute to resistance to sliding during orthodontic tooth movement. However, most attempts at reducing resistance aim only to reduce the archwire/ligature friction. In this study, a novel bracket with a unique design aimed to reduce all three components of resistance to sliding. Four types of brackets (passive and active self-ligating, traditionally ligated and the novel bracket, (n=5, each) were tested at 0, 2, 4, 6, and 8ᵒ of tip on a 0.019 x 0.025”archwire. The resistance to sliding values were recorded. At 0ᵒ, the passive self-ligating and novel bracket showed reduced resistance …

Treatment Decisions Involving Teeth With Intrapulpal Cracks: A Survey Of Endodontists, Sheldon M. Sealey

Theses and Dissertations

There is no universal protocol for diagnosing, treating and managing cracked teeth. The purpose of this survey was to investigate the use of traditional methods of crack detection and to explore how treatment decisions were made using an intrapulpal crack classification. The electronic survey was sent to 1115 active members of the American Association of Endodontists (AAE) and The Digital Office (TDO^™) community. Comparisons were assessed using logistic or repeated-measures regression. The most often used diagnostic method was probing. When the crack involved one wall, 85% of respondents would complete root canal therapy > 50% of the time or …