Digital Commons Network^™

Reducing Uncertainty In Head And Neck Radiotherapy With Plastic Robotics, Mark R. Ostyn

Theses and Dissertations

One of the greatest challenges in achieving accurate positioning in head and neck radiotherapy is that the anatomy at and above the cervical spine does not act as a single, mechanically rigid body. Current immobilization techniques contain residual uncertainties that are especially present in the lower neck that cannot be reduced by setting up to any single landmark. The work presented describes the development of a radiotherapy friendly mostly-plastic 6D robotic platform for positioning independent landmarks, (i.e., allowing remote, independent positioning of the skull relative to landmarks in the thorax), including analysis of kinematics, stress, radiographic compatibility, trajectory planning, physical …

Evaluation And Adaptation Of Live-Cell Interferometry For Applications In Basic, Translational, And Clinical Research, Kevin A. Leslie

Theses and Dissertations

Cell mass is an important indicator of cell health and status. A diverse set of techniques have been developed to precisely measure the masses of single cells, with varying degrees of technical complexity and throughput. Here, the development of a non-invasive, label-free optical technique, termed Live-Cell Interferometry (LCI), is described. Several applications are presented, including an evaluation of LCI’s utility for assessing drug response heterogeneity in patient-derived melanoma lines and the measurement of CD3+ T cell kinetics during hematopoietic stem cell transplantation. The characterization of mast cells during degranulation, the measurement of viral reactivation kinetics in Kaposi’s Sarcoma, and drug …

Efficient Information Dissemination In Vehicular Networks With Privacy Protection, Xiaolu Cheng

Theses and Dissertations

Vehicular ad hoc network (VANET) is a key component of intelligent transportation System (ITS). In VANETs, vehicles and roadside units exchange information for the purpose of navigation, safe driving, entertainment and so on. The high mobility of vehicles makes efficient and private communications in VANETs a big challenge.

Improving the performance of information dissemination while protecting data privacy is studied in this research. Meet-Table based information dissemination method is first proposed, so as to improve the information dissemination, and to efficiently distribute information via utilizing roadside units, Cloud Computing, and Fog Computing. A clustering algorithm is proposed as well, to …

Examining The Confirmatory Tetrad Analysis (Cta) As A Solution Of The Inadequacy Of Traditional Structural Equation Modeling (Sem) Fit Indices, Hangcheng Liu

Theses and Dissertations

Structural Equation Modeling (SEM) is a framework of statistical methods that allows us to represent complex relationships between variables. SEM is widely used in economics, genetics and the behavioral sciences (e.g. psychology, psychobiology, sociology and medicine). Model complexity is defined as a model’s ability to fit different data patterns and it plays an important role in model selection when applying SEM. As in linear regression, the number of free model parameters is typically used in traditional SEM model fit indices as a measure of the model complexity. However, only using number of free model parameters to indicate SEM model complexity …

Spillover Theory: Unintended Consequences Of Provisions In The Affordable Care Act, Robert T. Braun

Theses and Dissertations

Objective: To examine spillovers from a federal policy, managed care market, and community perspective.

Data Sources/Study Setting: We studied spillovers from a federal policy and managed care market perspective using the Health Care Utilization Project’s (HCUP) State Inpatient Database (SID). American Hospital Association (AHA) data, Interstudy Commercial Managed Care, and Area Health Resource File (AHRF). Medicare Advantage county-level payment schedules originate from CMS. We examined community uninsurance spillovers using 2011-2015 Medical Expenditure Panel Survey (MEPS), the Area Health Resource File (AHRF), and the Small Area Health Insurance Estimator (SAHIE).

Study Design: Ordinary Least Squares (OLS) and difference-in-difference regression analyses were …

Outcomes Associated With The Utilization Of Antidepressants And Psychotherapy Amongst Cancer Patients With Depression, Purva N. Parab

Theses and Dissertations

Objective: To determine patterns of use, prescription medicine costs, office-based visit costs and quality of life (QOL) across classes of antidepressants/psychotherapy in elderly cancer patients. Methods: Medical Expenditure Panel Survey data files from 2005-2015 for cancer patients with depression aged 18 years or older were used for the study. Frequencies of patients under specific classes of antidepressants/psychotherapy were identified. Costs and QOL scores were compared using Analysis of Variance (ANOVA). Generalized linear models, linear/multinomial logistic regression were used for analyses adjusted for demographics, overall health status, number and type of comorbidities. Results: The study sample consisted of 17,671 cancer patients …

Colloidal Synthesis And Photophysical Characterization Of Group Iv Alloy And Group Iv-V Semiconductors: Ge1-Xsnx And Sn-P Quantum Dots, Venkatesham Tallapally

Theses and Dissertations

Nanomaterials, typically less than 100 nm size in any direction have gained noteworthy interest from scientific community owing to their significantly different and often improved physical properties compared to their bulk counterparts. Semiconductor nanoparticles (NPs) are of great interest to study their tunable optical properties, primarily as a function of size and shape. Accordingly, there has been a lot of attention paid to synthesize discrete semiconducting nanoparticles, of where Group III-V and II-VI materials have been studied extensively. In contrast, Group IV and Group IV-V based nanocrystals as earth abundant and less-non-toxic semiconductors have not been studied thoroughly. From the …

The Role Of Vegetation-Topographic Interactions In A Barrier Island System: Island Migration In A Changing Climate, Benjamin Nettleton

Theses and Dissertations

Islands have been characterized based on vegetation and topography as exhibiting different disturbance regimes - reinforcing or resisting. This study had two objectives: quantify barrier island upland migration and vegetation cover change over 32 years (1984-2016), and assess tolerance of two prevalent dune grass species, A. breviligulata, and S. patens to sand burial. Using Landsat imagery from the Virginia Coast Reserve, islands were categorized within the disturbance resistance/reinforcing framework based on dune elevation. Resistant areas were associated with woody cover and low marsh to upland migration while reinforcing areas had low vegetation cover and high rates of migration. System-wide, …

Mass Spectrometry-Based Proteomics Analysis Of Secreted Proteins, Emmanuel K. Cudjoe Jr

Theses and Dissertations

Secreted proteins play important roles in many cellular functions and molecular processes. Because secreted proteins potentially enter the blood stream, they can serve as valuable measures of health and disease useful for disease diagnosis and prognosis, therapeutic target identification, and patient stratification in personalized medicine. Consequently, significant interest exists in secreted protein analysis within complex biospecimens, particularly blood but significant bioanalytical challenges including the wide protein dynamic range >10 orders of magnitude remain. The cellular secretome therefore represents a viable alternative to direct biomarker discovery in biofluids. Finally, cellular systems are amenable to labeling for the production of intact stable …

Housing Status, Patient Characteristics, And Ed Utilization Associated With Medication Prescribing At Ed Discharge Among Homeless And Nonhomeless Adults In Urban Hospitals In The United States, Lauren Cox

Theses and Dissertations

This cross-sectional study used a weighted sample of ED visits contained in the 2010-2015 years of the National Hospital Ambulatory Care Survey-Emergency Department (NHAMCS-ED) dataset. The purpose of this study was to: 1) identify differences in predisposing, enabling, and need characteristics, and ED use and medication prescribing characteristics between homeless and nonhomeless ED users; 2) assess the association between housing status and medication prescribing at ED discharge, and identify variables contributing to the disparity in medication prescribing between homeless and nonhomeless ED users; and 3) assess the predisposing, enabling, need, and ED use characteristics that predict medication prescribing at ED …

Metal-Organic Frameworks And Graphene-Based Support Materials For Heterogeneous Catalysis, Andrew Lin

Theses and Dissertations

Nanoparticles are involved in a broad range of applications, including heterogeneous catalysis. Nanoparticles tend to quickly lose their well-defined shapes and facets due to aggregation under duress such as heat.

A series of highly studied materials are explored as support materials for nanoparticle supports. These supports include metal-organic frameworks (MOF), graphene oxide (GO), and a MOF-PRGO (partially reduced graphene oxide) hybrid. The inclusion of a support with the palladium increased lifespan of the catalyst by separation of nanoparticles. The choice of support material not only allowed for supporting of palladium nanoparticles, but allowed for rational catalyst synthesis in order to …

Integral Measurement Of Atmospheric Particulate Matter (Pm), Di Liu

Theses and Dissertations

Atmospheric aerosol particles also known as atmospheric particulate matter or particulate matter (PM) are microscopic particles (solid or liquid) suspended in air, which is one of six air pollutants in US air quality standard. PM is classified as coarse particles with diameters between 2.5 to 10 mm, fine particles with a diameter less than 2.5 mm (PM_2.5), and ultrafine particles with the diameter less than 0.1 mm (PM_0.1). Epidemiological studies have already showed the adverse health effects (such as asthma, lung cancer and respiratory and cardiovascular disease) resulted from exposure to the fine and ultrafine particles. …

Role Of C121a In Mglur2 Homodimeric Expression And Function, Jong M. Shin

Theses and Dissertations

The group II metabotropic glutamate receptors are known for their involvement in various psychiatric disorders. The mGluR2 in particular is linked with etiology of schizophrenia especially in the context of crosstalk with 5-HT2A. Thus, the mGluR2 has attracted attentions for its potential therapeutic applications. Despite numerous physiological evidences on the actions of mGluR2, its mechanism is still unclear to this day. It is partially due to the lack of understanding in characteristics of mGluR2 homodimer which is its functionally active form. Therefore, the characterization of dimeric interaction serves as a foundation to advanced understanding of the role of mGluR2. On …

In Vitro Genetic Code Expansion And Selected Applications, Emil S. Iqbal

Theses and Dissertations

The ability of incorporation non-canonical amino acids (ncAAs) using translation offers researchers the ability of extend the functionality of proteins and peptides for many applications including synthetic biology, biophysical and structural studies, and discovery of novel ligands. Here we describe the three projects where the addition of ncAAs to in vitro translation systems creates useful chemical biology techniques. In the first, a fluorinated histidine derivative is used to create a novel affinity tag that allows for the selective purification of peptides from a complex mixture of proteins. In the second, the high promiscuity of an editing-deficient valine-tRNA synthetase (ValRS T222P) …

Investigating Racial Bias In Perceptions Of Free Will, Courtney J. Alderson

Theses and Dissertations

The overarching goal of this study was to examine whether perceptions of others’ free will would differ depending on perceiver race as well as target race. The current study proposed that such a racial bias may be one mechanism by which racial disparities in medical treatment recommendations arise. By bridging findings from four different lines of research (i.e., the literatures on racial health and medical treatment disparities, racial bias, free will beliefs, and social identity), it was hypothesized that: (1) participants would perceive greater amounts of free will for a hypothetical racial ingroup patient than an outgroup patient; (2) such …

An Investigation Of Electronic Cigarette Aerosol Mixture On Craniofacial Development In Mouse Embryos, Suraj Kandalam

Theses and Dissertations

E-cigarette (e-cig) use has increased in recent years among teenagers and young adults. E-cigs are battery-powered nicotine delivery systems that vaporize e-liquids, a solution composed of propylene glycol (PG), vegetable glycerin (VG), nicotine, flavoring, and coloring agents. The aim of this study was to determine the effects of exposure to e-cig aerosol mixtures (e-cigAMs) on proliferation, migration, and differentiation of NCCs in vitro and craniofacial development in mouse embryos in vivo. E-cigAM was produced by bubbling e-cig aerosol into saline. E-cigAMs were generated for unflavored e-liquid of increasing PG: VG ratio. Metabolic activity (MA), gene expression, migration, and proliferation …

Hydrophobicity Of Low Temperature Vibrating Surfaces, Christian Fergusson

Theses and Dissertations

This study proposes a method to enhance the anti-icing capabilities of superhydrophobic surfaces by utilizing vibration to further reduce contact time of an impacting droplet in addition to keeping the droplet in the Cassie-Baxter regime, where surface adhesion is lower than the opposing Wenzel regime. We tested this with two methods: by investigating the effects of vibration normal to the plane of a superhydrophobic surface being impacted by water droplets in a room temperature environment, with the surface horizontal in a room temperature environment and tiled in a subzero degree environment. The amplitude and frequency of the vibration were varied …

Heteroatom Doped Porous Carbon For Alternative Energy Conversion And Storage Systems, Fatema A. Choudhury

Theses and Dissertations

Abstract

The electrocatalysis of oxygen plays a significant role in several electrochemical energy storage and conversion systems including metal−air batteries, fuel cells, electrocatalytic and photocatalytic water splitting. The sluggish kinetics and complex reaction mechanism of this cathodic oxygen reduction reaction (ORR) affect the performance and practical application of such renewable energy technologies. To address this limiting factor, a suitable electrocatalyst is required for ORR. In general, platinum or highly dispersed Pt-based nanoparticles on carbon black are considered as the best ORR catalyst. But platinum being very scarce and expensive tends to increase the cost. Moreover, platinum-based catalysts are prone to …

Elucidation Of Substrate Binding Interactions For Human Organic Cation Transporters 1 (Slc22a1) And 2 (Slc22a2) Using In Silico Homology Modeling In Conjunction With In Vitro Site-Directed Mutagenesis And Kinetic Analysis, Raymond E. Lai

Theses and Dissertations

The organic cation transporters (OCTs) play a critical role in the absorption, distribution and elimination of many drugs, hormones, herbal medicines, and environmental toxins. Given the broad substrate specificity of OCTs, they fall victim to the high susceptibility for contributing to harmful drug-drug interactions. Further defining how human (h)OCTs mechanistically bind to its broad array of substrates will provide significant insight to the understanding and prediction of drug-drug interactions in polypharmacy patients and the advancement of future rational drug design for therapeutics targeting OCTs. The goal of the current study was to elucidate the critical amino acid residues for transporter-substrate …

Perceived Financial Burden, Self-Management Behaviors, And Glycemic Control In Adults With Type 1 Diabetes, Megan Peter

Theses and Dissertations

People with type 1 diabetes must perform frequent self-management behaviors to maintain glycemic control. Those with higher diabetes distress tend to have worse glycemic control, indicated by higher A1C. Financial stress is common in adults with chronic diseases, but little is known about perceived financial burden in adults with type 1 diabetes or its associations with diabetes distress, self-management behaviors, or A1C. It is also unknown whether diabetes self-efficacy moderates the associations between perceived financial burden or diabetes distress with self-management behaviors.

Surveys were collected from 235 adults with type 1 diabetes. Structural equation modeling tested whether perceived financial burden …

Why Local Governments Collaborate: Perspectives From Elected Officials And Local Government Managers On Regional Collaboration, Stephanie D. Davis

Theses and Dissertations

This study examined the factors that influence a local government’s decision to engage in regional collaborations. Analysis of 7 local government managers and eleven elected officials revealed that the decision to engage in regional collaboration was influenced by external factors, organizational factors, and internal motivations. Elected officials and local government managers identified a disaster occurrence, fiscal stress, outside agencies, jurisdictional benefit, and communication as key factors. Further, this research highlights the importance of the role of the elected official in intergovernmental arrangements, the role of the local government manager as the policy entrepreneur, and the influence of shared norms and …

Differences In Spatial Visualization Ability And Vividness Of Spatial Imagery Between People With And Without Aphantasia, Anita Crowder

Theses and Dissertations

Mathematics education researchers have examined the relationship between visualization and mathematics for decades (e.g., Arcavi, 2003; Bishop, 1991; Duval, 1999; Fennema & Tartre, 1985; Presmeg, 1986). Studies have linked spatial visualization ability, such as measured in mental rotation tasks, directly to mathematics self-efficacy (Pajares & Kranzler, 1995; Weckbacher & Okamoto, 2014), which in turn influences mathematics achievement (Casey, Nuttall, & Pezaris, 1997). With the important role that spatial visualization plays in learning mathematics, the recent identification of congenital aphantasia (Zeman, Dewar, & Della Sala, 2015), which is the lack of mental imagery ability, has raised new questions for mathematics education …

International Student Participation In Postsecondary U.S. English Language Programs, Valeriana Colon

Theses and Dissertations

Postsecondary English language education is a growing industry in the United States. While there has been considerable research on international student mobility in higher education, there is limited research on the population’s participation in U.S. English language programs (ELPs). The purpose of the study was to apply existing theories and data analysis to understand postsecondary English language program participation and create a foundation for future studies. This exploratory study examined the characteristics of international students enrolled in U.S. postsecondary ELPs. The researcher investigated the relationship between ELP enrollment with U.S. higher education enrollment as well as the relationship between ELP …

Exploring Literacies In The Assemblage Of Adult Education English For Speakers Of Other Languages Classrooms, Susan Watson

Theses and Dissertations

The purpose of this dissertation is to provide a posthuman perspective of adult second language and literacy learning using the philosophy of Gilles Deleuze and his collaborative work with Félix Guattari, Masny’s (2005/6) multiple literacies theory or MLT, and DeLanda’s (2016) assemblage theory. Thinking with these scholars, I employ a post-qualitative, posthuman MLT conceptual framework to study literacy as a process that flows through and connects with globally-diverse students, languages, worldviews, and texts in the assemblage of adult education, English for speakers of other languages (ESOL) classrooms. I posit this assemblage as a remarkable and important context for literacy research …

Prosecution As The "Soul Crushing Job:" Complexities Of Campus Sexual Assault Cases, Tammi L. Slovinsky

Theses and Dissertations

On April 4, 2011, the U.S. Department of Education issued a Dear Colleague Letter on campus sexual assault reaffirming the intent of Title IX, the 1972 law that prohibits discrimination sex-based under any education program or activity receiving federal financial assistance. In response to growing concern over due process rights for defendants, in September 2017 the guidance was rescinded. Public policy continues to evolve, leading to potentially lasting institutional changes on many college campuses. These developments include the formalization of campus investigations and adjudications, the development of campus coordinating committees and expanded support mechanisms for victims. In Virginia, laws passed …

Novel Support Vector Machines For Diverse Learning Paradigms, Gabriella A. Melki

Theses and Dissertations

This dissertation introduces novel support vector machines (SVM) for the following traditional and non-traditional learning paradigms: Online classification, Multi-Target Regression, Multiple-Instance classification, and Data Stream classification.

Three multi-target support vector regression (SVR) models are first presented. The first involves building independent, single-target SVR models for each target. The second builds an ensemble of randomly chained models using the first single-target method as a base model. The third calculates the targets' correlations and forms a maximum correlation chain, which is used to build a single chained SVR model, improving the model's prediction performance, while reducing computational complexity.

Under the multi-instance paradigm, …

Novel Insights Into The Contribution Of Cellular Senescence To Cancer Therapy: Reversibility, Dormancy And Senolysis., Tareq Saleh

Theses and Dissertations

Cellular senescence a specialized form of growth arrest that contributes to the pathogenesis of several aging-related disorders including cancer. While by definition tumor cells are considered immortalized, they can undergo senescence when exposed to conventional and targeted cancer therapy. Therapy-Induced Senescence (TIS) represents a fundamental response to therapy and impacts its outcomes. However, TIS has been considered a positive therapeutic goal since senescent tumor cells are expected to enter a state of permanent growth abrogation. In this work we examined the hypothesis that a subpopulation of senescent cells can re-acquire proliferative potential after a state of senescent dormancy, indicating that …

Communicating Colorectal Cancer Risk To Average Risk Adults: Examining The Impact On Risk Perceptions And Health Behavior Intentions, Carrie A. Miller

Theses and Dissertations

Background. CRC risk can be reduced though lifestyle modification and regular screenings. Providing CRC risk feedback that promotes preventive behaviors to those at average risk has the potential to significantly reduce CRC morbidity and mortality.

Purpose. The purpose of this dissertation was to examine the impact of CRC risk assessment feedback among adults aged 50-75 with no personal or family history of the disease. The specific aims were to: (1a) test personalized (vs. generic) risk assessment feedback on individuals’ risk perceptions and intentions to engage in three risk-reducing behaviors (e.g., physical activity, diet, and screening); (1b) determine if the provision …

Validation Of Virginia's Juvenile Risk Assessment Instrument, Jessica P. Schneider

Theses and Dissertations

Utilizing a validated risk assessment tool to predict future offending is recommended as best practices in corrections by a number of professional organizations (Latessa & Lovins, 2010). Guided by the risk-needs-responsivity model, risk assessment tools have evolved to help inform criminal justice practitioners by identifying offenders most in need of intervention or supervision, guiding the case plan to optimize outcomes (Bonta & Andrews, 2007). The Virginia Department of Juvenile Justice (DJJ) utilizes the Youth Assessment and Screening Instrument (YASI) at all stages of contact with youthful offenders, including intake, probation, commitment, and parole (DJJ, 2016). However, risk assessment instruments do …

The Interaction Between Ceramide-1-Phosphate And Group Iva Cytosolic Phospholipase A2 And Its Role In Wound Healing, Patrick Macknight

Theses and Dissertations

The sphingolipid, ceramide-1-phosphate (C1P), directly binds and activates Group IVA cytosolic phospholipase A₂ (cPLA₂a) to generate eicosanoids. Due to the role of eicosanoids in wound healing, we choose to use our novel genetic mouse model expressing cPLA₂a with an ablated C1P interaction site (KI) to examine the cPLA₂a/C1P interaction in wound healing. Wound closure rate was not affected, but wound maturation was dramatically enhanced by loss of the C1P/cPLA₂α interaction based on the following findings. Wounds in KI mice displayed: i) increased infiltration of dermal fibroblasts into the wound environment; ii …