Electrical And Magnetic Transport Properties Of Periodic And Aperiodic Artificial Spin Ice Systems, Justin Woods

Theses and Dissertations--Physics and Astronomy

In recent years, the topic of magnetic frustration in systems and the effect that frustration can have on system dynamics has been a rich environment for study. One such system that lends itself directly to this study are systems of single domain ferromagnetic bars in two dimensions. These ferromagnetic bars can be fabricated from a thin film using current lithography techniques. The bars are fabricated in such a way that their shape anisotropy dictates the magnetization of the bar will be a single domain, Ising-like magnetic moment. These single domain magnetic bars scan be arranged to introduce frustration of their …

Sensitivity Of Electron-Proton Coincidence Asymmetries In Neutron Beta-Decay To Scalar And Tensor Interactions, Subash C. Nepal

Theses and Dissertations--Physics and Astronomy

We study the combined sensitivity of measurements of electron-proton coincidence asymmetries in polarized neutron beta-decay together with a measurement of the electron energy spectrum in unpolarized neutron beta-decay to beyond Standard Model (BSM) scalar and tensor interactions, via the appearance of such BSM physics in the Fierz interference terms b and b_v. Whereas measurements of the electron energy spectrum directly probe b, both the proton and neutrino asymmetries for which experimental results exist are not sensitive to b_v, but effectively to b - b_v. This results in reduced sensitivity to BSM scalar and …

A Theoretical And Experimental Study Of Charge Transport In Organic Thermoelectric Materials And Charge Transfer States In Organic Photovoltaics, Ashkan Abtahi

Theses and Dissertations--Physics and Astronomy

Applications of organic electronics have increased significantly over the past two decades. Organic semiconductors (OSC) can be used in mechanically flexible devices with potentially lower cost of fabrication than their inorganic counterparts, yet in many cases organic semiconductor-based devices suffer from lower performance and stability. Investigating the doping mechanism, charge transport, and charge transfer in such materials will allow us to address the parameters that limit performance and potentially resolve them. In this dissertation, organic materials are used in three different device structures to investigate charge transport and charge transfer. Chemically doped π-conjugated polymers are promising materials to be used …

Effects Of Aperiodicity And Frustration On The Magnetic Properties Of Artificial Quasicrystals, Barry Farmer

Theses and Dissertations--Physics and Astronomy

Quasicrystals have been shown to exhibit physical properties that are dramatically different from their periodic counterparts. A limited number of magnetic quasicrystals have been fabricated and measured, and they do not exhibit long-range magnetic order, which is in direct conflict with simulations that indicate such a state should be accessible. This dissertation adopts a metamaterials approach in which artificial quasicrystals are fabricated and studied with the specific goal of identifying how aperiodicity affects magnetic long-range order. Electron beam lithography techniques were used to pattern magnetic thin films into two types of aperiodic tilings, the Penrose P2, and Ammann-Beenker tilings. SQUID …

Effect Of An Educational Intervention On Coronary Artery Disease Knowledge In Men And Women At Risk For Coronary Artery Disease, Rochelle Anderson-Doyley

Doctor of Nursing Practice Projects

Background

Coronary artery disease (CAD) is the leading cause of death in the United States. The management of CAD, a preventable disease, has significant implications for health and wellness outcomes in the United States. Decades of research have examined the role and effectiveness of an educational intervention in promoting the patient's knowledge of and ability to manage risk factors for CAD. This project examined the effectiveness of an educational tool implemented in a primary care setting in improving patients' knowledge about CAD risk factors.

Method

The research design was a non-experimental one-group pre-test and post-test design. After receiving institutional review …

Statistical Analysis Of Demographic Effects On Insurance Coverage Of Perinatal And Neonatal Morbidity, Madeline Durbin

Undergraduate Honors Thesis Projects

In the United States of America, Ohio has one of the worst neonatal and perinatal death rates. Within Ohio, Montgomery County has an above average neonatal and perinatal death rate. This statistic can be lowered if more women in Montgomery County have health insurance. They would be more likely to seek out prenatal health care, since they would no longer have to pay as much money out-of-pocket. This would allow medical professionals to be able to diagnose and treat any potential issues in the mother or child earlier. Having health insurance would also prevent mothers-to-be from seeking out other potentially …

Epidemiology Of Soccer‐Related Head Injury In Children 5–14 Years In Victoria, Australia, Amy E. Smith, Catherine Krejany, Moyez Jiwa

Medical Papers and Journal Articles

Aim: Our aim was to use epidemiological data to determine the incidence of soccer‐related head injuries in children aged 5–14 years who presented at emergency departments (EDs) or were admitted in hospitals in Victoria, Australia.

Methods: ED presentation and hospital admission de‐identified aggregate data were from the Victorian Injury Surveillance Unit. Soccer participation data were compared with the soccer‐related head injury data to determine the incidence of this injury among these children.

Results: The incidence of ED presentations was 0.17% of children participating in soccer during the study period (financial years 2011–2012 to 2015–2016). The 10–14‐years age group presented with …

Political Ideology Of The Board And Ceo Dismissal Following Financial Misconduct, Uisung Park, Warren Boeker, David Gomulya

Research Collection Lee Kong Chian School Of Business

Why do some boards refuse to take serious action against CEOs who have committed financial misconduct? Past work has directed attention to the antecedents of misconduct while largely overlooking this question. The relatively few studies to examine it have typically revolved around the capacity of boards to take action, or their relationships to their CEOs. This study instead examines how the beliefs and values held by board members can influence their actions following financial misconduct. Focusing on political ideology, we argue and find that politically conservative boards are more likely to respond by dismissing the CEO than are liberal boards. …

Natural Lead-In Approaches To Response-Adaptive Allocation In Clinical Trials, Erin E. Donahue

Theses and Dissertations

Response-adaptive (RA) allocation designs can be implemented in clinical trials to skew the allocation of incoming subjects toward the better performing treatment group based on the previously accrued subjects' responses. These designs alleviate potential ethical concerns of equally allocating subjects in a trial when one treatment arm is inferior. The RA design can be generalized to include covariate information in the covariate-adjusted response-adaptive (CARA) design, which aims to maximize treatment successes conditional on a set of patient characteristics. While RA and CARA designs can improve the treatment of patients, they have unstable estimators and increased variability in early stages of …

Generation Of Warm Dense Plasma On Solar Panel Infrastructure In Exo-Atmospheric Conditions, Harrison C. Wenzel

Theses and Dissertations

The use of a weaponized thermo-nuclear device in exo-atmospheric conditions would be of great impact on the material integrity of orbiting satellite infrastructure. Particular damage would occur to the multi-layered, solar cell components of such satellites. The rapid absorption of X-ray radiation originating from a nuclear blast into these layers occurs over a picosecond time scale and leads to the generation of Warm Dense Plasma (WDP). While incredibly difficult and costly to replicate in a laboratory setting, a collection of computational techniques and software libraries may be utilized to simulate the intricate atomic and subatomic physics characteristics of such an …

An Intersectional Analysis Of Disproportionality Of Dual Language Learners In Special Education In Virginia: A Mixed Methods Study, Melissa J. Cuba

Theses and Dissertations

The disproportionality of dual language learners (DLLs) in special education has been a persistent and complex issue for decades. These students have multidimensional identities that require a look at how they are positioned in school systems and the broader social landscape. Using a multilevel model of intersectionality and an explanatory mixed methods design, this study examines how social categories, practice, and policies influence the representation of DLLs in special education in Virginia, a state where DLLs represented 13 percent of the total student population in 2018-19. Findings from this study reveal overrepresentation and underrepresentation of 63 DLL subgroups using nuanced …

Phenotype Extraction: Estimation And Biometrical Genetic Analysis Of Individual Dynamics, Kevin L. Mckee

Theses and Dissertations

Within-person data can exhibit a virtually limitless variety of statistical patterns, but it can be difficult to distinguish meaningful features from statistical artifacts. Studies of complex traits have previously used genetic signals like twin-based heritability to distinguish between the two. This dissertation is a collection of studies applying state-space modeling to conceptualize and estimate novel phenotypic constructs for use in psychiatric research and further biometrical genetic analysis. The aims are to: (1) relate control theoretic concepts to health-related phenotypes; (2) design statistical models that formally define those phenotypes; (3) estimate individual phenotypic values from time series data; (4) consider hierarchical …

Teachers' Perceptions Of The Broad Validity Of A High Stakes English Language Proficiency Test, Carolyn N. Waters

Theses and Dissertations

The No Child Left Behind Act of 2001 mandated that the English acquisition of all students identified as English learners be assessed annually using high-stakes standardized English language proficiency tests, and the Every Student Succeeds Act of 2015 continues this testing mandate. The WIDA ACCESS for ELLs® has been used for this and other purposes since 2005, and has been adopted by 40 State Education Agencies, including the Virginia Department of Education. However, despite the long-standing and widespread use of this assessment, no comprehensive independent evaluations of the test have been conducted. This mixed-methods study is a conceptual replication of …

The Design Of A New Vaginal Applicator For Direction Modulated Brachytherapy (Dmbt) Using Geant4 Monte Carlo Simulation Code, Moeen Meftahi

Theses and Dissertations

Purpose: Anisotropy of the 192Ir source causes a lack of dose coverage at the apex in HDR vaginal cylinder brachytherapy (VC BT). In this study, we took advantage of the GEANT4 Monte Carlo (MC) simulation code to design a new DMBT vaginal applicator so that it maintains the dose coverage of the current vaginal cylinder at periphery everywhere while improving the apex coverage. In addition, since current treatment planning systems (TPS) considers the whole environment as water according to TG43 formalism, based on the capability of the MC in the calculation of dose in the material, the effect of inhomogeneity …

Robert Catherine, Sarah Nelson Rupp

Theses and Dissertations

Robert Catherine is an experimental augmented reality novel engaged in the speculative realist question: What is the point to anything if everything?

A perverted and downwardly mobile Richmond millennial man quarantined because of the Coronavirus writes a series of creative non-fiction essays for his girlfriend about suicide, panic attacks, ADHD, DNA testing, capitalism, depression, and sexual repression.

Peridynamic Approaches For Damage Prediction In Carbon Fiber And Carbon Nanotube Yarn Reinforced Polymer Composites, Forrest E. Baber

Theses and Dissertations

Aerospace structures are increasingly utilizing advanced composites because of their high specific modulus and specific strength. While the introduction of these material systems can dramatically decrease weight, they pose unique certification challenges, often requiring extensive experimental testing in each stage of the design cycle. The expensive and time-consuming nature of experimental testing necessitates the advancement of simulation methodologies to both aid in the certification process and assist in the exploration of the microstructure design space.

Peridynamic (PD) theory, originating from Sandia National Lab’s in the early 2000’s, is a nonlocal continuum-based method that reformulates the equation of motion into an …

A Cost-Effectiveness Analysis Of Early Literacy Growth In Public Pre-Kindergarten Programs, Bruce A. Fillman

Theses and Dissertations

Student early literacy readiness is predictive of later academic success and pre-k programs are a proven intervention to develop early literacy; however, the cost of pre-k programs differs greatly. These differences in cost are related to the opportunities and services included within each program. This study examined four pre-k programs offered within a large school system in Virginia to determine if there were differences in students’ early literacy growth by program attended and evaluated the ratio of cost to achievement of each pre-k program to determine their cost-effectiveness. To do this, two one-way analyses of variances (ANOVAs) were conducted to …

Heparan Sulfate. A Ligand For Coordination Compounds., Eric Ginsburg

Theses and Dissertations

Heparan sulfate (HS), a type of glycosaminoglycan (GAG), has been identified as a ligand for interactions with polynuclear platinum complexes (PPCs). HS is involved in numerous biological processes, and often considered to be extracellular DNA. PPCs interact with HS through the formation of a “sulfate clamp”, where multiple anionic sulfate groups cluster around the cationic PPC. The masking of HS results in the inhibition of enzymatic activity, protein-HS interactions, and other biological processes. PPCs use HS proteoglycans as an method of cellular internalization. By targeting sulfated-GAGs, PPCs can offer precision medicine not currently observed with the FDA approved platinum therapies. …

Smallest Worthwhile Effect Values For Pain And Function After A Total Knee Replacement, Nancy Wofford

Theses and Dissertations

ABSTRACT

SMALLEST WORTHWHILE EFFECT VALUES FOR PAIN AND FUNCTION AFTER A TOTAL KNEE REPLACEMENT

Nancy Henderson, PT

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

Virginia Commonwealth University, 2020

Dr. Dan Riddle, PT, PhD, Physical Therapy

Meaningful change is an important concept in healthcare as it allows providers to better understand the efficacy of an intervention. Three commonly used methods to assess meaningful change include the distribution-based, anchor-based, and benefit-harm trade-off methods. The benefit-harm trade-off method improves upon the limitations of the distribution-based and anchor-based methods. Unlike the …

Electrocatalytic Cathodes For Advanced Lithium–Sulfur Batteries, Ahmed Abdelkader

Theses and Dissertations

Energy demands are anticipated to increase in the next decades with the consumption of fossil fuels predicted to grow from the current levels. This will place an enormous burden on the non–renewable reserves of our energy sources and add to the preexisting environmental crisis with the emission of greenhouse gases like carbon dioxide (CO₂). Electrical energy storage (EES) is considered one of the most crucial needs of modern society to circumvent this crisis and potential applications include electric vehicles and devices, as well as storage systems for solar and wind sources.Lithium–ion batteries (LIBs) have proven to be …

Symmetry Algebras Of The Canonical Lie Group Geodesic Equations In Dimension Five, Hassan Almusawa

Theses and Dissertations

Nowadays, there is much interest in constructing exact analytical solutions of differential equations using Lie symmetry methods. Lie devised the method in the 1880s. These methods were substantially developed utilizing modern mathematical language in the 1960s and 1970s by several different groups of authors such as L.V. Ovsiannikov, G. Bluman, and P. J. Olver, and have since been implemented as a software package for symbolic computation on commonly used platforms such as Mathematica and MAPLE.

In this work, we first develop an algorithmic scheme using the MAPLE platform to perform a Lie symmetry algebra identification and validate it on nonlinear …

Modeling The Evolution Of Barrier Islands, Greg Robson

Theses and Dissertations

Barrier islands form off the shore of many coastal areas and serve as the first line of defense, protecting littoral communities against storms. To study the effects that climate change has on barrier islands, we use a cellular model of wind erosion, surface dynamics, beach dynamics, marsh dynamics, and vegetation development. We will show the inhibition of movement when vegetation is present.

Sensory Substitution, Key To Inclusive Learning, Fathima Z. Zahir

Theses and Dissertations

Visually impaired students, in primary education, encounter unique challenges while learning creative skills, exploring artistic expression and developing problem-solving skills, because so much instructional content is delivered visually. Sensory substitution—an approach that replaces visual information with feedback from other intact senses like touch, sound, taste or smell—provides an opportunity to address those challenges.

Through the use of sensory substitution, this thesis proposes concrete ways to capitalize on the enhanced abilities of visually impaired primary school students. The research outcome of this thesis is a system of templates that puts these enhanced abilities to work for visually impaired students, to support …

Three Studies Of Research-Based Pedagogy In Physical Chemistry: Development Of A Zno Thin Film Experiment, Analysis Of Student Discourse By Graph Theory And Cognitive Engagement, Building A Physical Chemistry Faculty Network., Dilhara Liyanage

Theses and Dissertations

Three research projects, each focusing on a different aspect, development of a ZnO thin film experiment, student’s cognitive engagement behavior, and building of a faculty network, are presented in this dissertation.

In the first project, a physical chemistry laboratory experiment was developed to answer the question, “How do electrons move in a solid?”. The experiment structure follows the POGIL-PCL (Process Oriented Guided Inquiry Learning - Physical Chemistry Laboratory) model. Students begin by using the PhET “Quantum Bound States” animation to compare energy levels for single atoms to energy levels of a lattice containing many potential wells, and they incorporate that …

Mathematical Models Of Cellular Signaling And Supramolecular Self-Assembly, Pratip Rana

Theses and Dissertations

Synthetic biologists endeavor to predict how the increasing complexity of multi-step signaling cascades impacts the fidelity of molecular signaling, whereby cellular state information is often transmitted with proteins diffusing by a pseudo-one-dimensional stochastic process. We address this problem by using a one-dimensional drift-diffusion model to derive an approximate lower bound on the degree of facilitation needed to achieve single-bit informational efficiency in signaling cascades as a function of their length. We find that a universal curve of the Shannon-Hartley form describes the information transmitted by a signaling chain of arbitrary length and depends upon only a small number of physically …

Fabrication And Characterization Of Multicomponent Gradients Containing Weakly Acidic And Basic Functional Groups, Kallol Roy

Theses and Dissertations

Multicomponent synthetic chemical gradients containing amine (NH₂) and carboxylic acid (COOH) groups have been prepared on the silanol (Si-OH) containing a base-layer substrate by the controlled-rate infusion (CRI) method. The spatial variation of weakly acidic COOH and basic NH₂ functional groups on weakly acidic Si-OH surface was created in such a way that the two antagonist groups at high concentrations were in close proximity (aligned gradient) and were separated (opposed gradient). The difference in concentration of different components (acid, base, or silanol) along the length of aligned or opposed resulted in significantly different physicochemical properties …

Structure, Morphology And Composition-Property Elucidation Of Ni–Mo And Ni−Mo−P Nanocrystals For Water Splitting Reactions And Group Iv Alloy And Silicate Nanocrystals For Visible To Near Ir Optoelectronics, Ebtesam Hassan Abuelenein Eladgham

Theses and Dissertations

Abstract

Structure, Morphology and Composition-Property Elucidation of Ni–Mo and Ni−Mo−P Nanocrystals for Water Splitting Reactions and Group IV Alloy and Silicate Nanocrystals for Visible to Near IR Optoelectronics

by

Ebtesam Hassan Abuelenein Eladgham

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

Advisor: Indika U Arachchige

Associate Professor, Department of Chemistry

Nanomaterials have gained a great attention because of their unique physical properties with size intermediate between molecular materials and extended solids. They have a large surface to volume ratio and display size tunable physical properties that was not …

A Graph Theoretical Approach To The Dollar Game Problem, Rachel Koch

Theses and Dissertations

In this thesis we consider a problem in Graph Theory known as the Dollar Game. The Dollar game was first introduced by Matthew Baker of the Georgia Institute of Technology in 2010. It is a game of solitaire, played on a graph, and is a variation of chip firing, or sand-piling games. Baker approached the problem within the context of Algebraic Geometry. It is the goal of this paper to provide an overview of the necessary graph theory to understand the problem presented in this game, as well as background on chip firing games, their history and evolution. Finally we …

Martian Mother, Elizabeth Mcgrady

Theses and Dissertations

This paper examines the relationship between humans and land, through the lens of the scientific and religious, bridging the physical realm with the spiritual. It acts as accompanying material to the project titled Martian Mother, supplementary information to the visual work, and an extension of the proposal, the center of the work. The proposal exists to send myself, or a like-minded individual, to Mars with artificial insemination equipment to give birth to the first Martian, becoming the first Martian Mother. This work is rooted firmly in speculative fiction, creating a nonlinear future framework for a new society and space exploration.

Arabic Beyond Arabic, Abir Zakzok

Theses and Dissertations

Arabic is the best and the most complicated language of all time!” Even though this statement seems like an exaggeration, it is what I grew up hearing; from my Arab parents as a child, my Arab teachers as a student, and my Arab customers as a salesperson. The Arabic language has a significant role in Arabs’ identity, yet most Arabs only scratch the surface and do not fully grasp the embedded meaning of the language. I have long been fascinated by the relationship between language and community as well as how it translates to design - specifically, the relationship between …