Digital Commons Network^™

Investigation Of Brain Function And Structural Development As Risk Factors Of Suicidal Thoughts And Behaviors, Yi Zhou

Theses and Dissertations

Background: Identifying risk factors for suicidal thoughts and behaviors, especially causal ones, will be imperative to improving screening and treatment interventions. To identify replicable brain-based risk factors, there is increasing evidence indicating the need for large sample sizes, in the hundreds to thousands, in order to achieve a sufficient level of statistical power to detect them. Furthermore, longitudinal studies of brain and behavioral factors will be essential to understanding how suicide develops, especially the transition from suicide ideation to attempt. While experimental studies may not be feasible or ethical, genetically informed methods for testing evidence for causation are an alternative …

Mathematical Analysis Of Eukaryotic Pericentromere, Puranjan Ghimire

Theses and Dissertations

The centromere is crucial for chromosomal stability and their proper segregation during cell division in eukaryotes. Surrounding the centromere are pericentromeres, made of repetitive DNA elements called pericentromeric repeats, varying from 10 in fission yeast to thousands in humans. These repeats form densely packed heterochromatin, where genes are usually silenced. The silencing mechanism across different pericentromeric repeats remains unclear.

Despite variations in sequence and length, pericentromeric repeats are conserved across eukaryotes, indicating their functional importance. This dissertation presents mathematical models to quantify gene silencing in fission yeast and humans. In fission yeast, my model predicts that silencing occurs only with …

A Complexity Aware Overlay Architecture For High Integrity Fpga Based Systems, Richard Dwight Hite Jr

Theses and Dissertations

Cyber-Physical systems are becoming more and more prevalent in our society and are simultaneously becoming more complex due to evolving technological capabilities in both hardware and software. This complexity exacerbates verification and validation activities thereby negatively impacting important system attributes like design assurance, system reliability, development costs and trust. These facts necessitate the need for computing architectures that constrain complexity for the sake of assurance. Traditional software and hardware development for safety-critical systems have been demonstrated in previous safety-critical systems and the established development methodologies are well understood. However, both technologies have their strengths and limitations. Processor-based technology (SW based …

Advanced Synthesis And Rational Design Of Support Structures For Nobel Metal Heterogeneous Catalysis: Towards Enhanced Activity And Continuous Processes, Brian R. Clark

Theses and Dissertations

The field of catalysis has a wide-ranging impact. Our group has identified the constant need for improved catalytic activity in high-impact applications such as hydrosilylation and cross-coupling reactions. For these reactions, precious metal catalysts often exhibit markedly better performance than their counterparts, but they can be a significant process cost that decreases overall economic efficiencies. To address this challenge, we explored support structures that can enhance catalytic activity at low metal loadings and improve precious metal recovery through simple filtration. We found that a platinum on graphene nanoplatelet catalyst (PtGNP) synthesized via strong electrostatic adsorption with microwave irradiation (SEA-MW) exhibits …

Transforming Children's Oral Health: The Impact Of Oral Healthcare Policies On Virginia Medicaid Dental Health Outcomes., Anita M. Kumar

Theses and Dissertations

Abstract: Transforming Children's Oral Health: The Impact of Oral Healthcare Policies on Virginia Medicaid Dental Health Outcomes.

Objectives: This dissertation uses Department of Medical Assistance Services (DMAS) administrative files at the individual and provider level from fiscal years (FY) 2011 to 2021 to systematically study the effect of recently implemented oral health policies (EBD guidelines on sealants, CMS updated quality measures, expansion of Medicaid oral healthcare for qualifying pregnant women) on oral health outcomes of Virginia Medicaid-enrolled children.

Methods: The studies employ a difference in differences regression methods (negative binomial, Poisson, and logistic) to examine the effects of oral health …

Exploration Of Dopaminergic And Serotonergic Pathways Utilizing Pleiotropic Agents, Charles B. Jones Iii

Theses and Dissertations

2-(Benzoyl)piperidines (BPs) are at a crossroads of therapy and abuse. These compounds are a hybrid between the ADHD medication methylphenidate and abused stimulant cathinones. Here we use computational molecular modeling, synthesis, mutagenesis, and epifluorescence microscopy to further improve the understanding of and potential treatments for several neuropsychiatric disorders. Utilizing the BP scaffold and controlling chirality and aryl substitution, these agents were examined at DAT and SERT. From these investigations it has now been established that R isomer BPs are favored for DAT while S isomer BPs are favored for SERT. Aryl-substitution can greatly affect the selectivity of these agents with …

Synthesis Of Lithium Nickel Cobalt Manganese Oxide (Ncm) Cathodes For Lithium-Ion Batteries, Jethrine H. Mugumya

Theses and Dissertations

There are various ways to produce lithium nickel manganese cobalt oxide (NCM) based cathodes for lithium-ion batteries, among them; co-precipitation synthesis carried out in tank-based reactors followed by lithiation is commonly employed because of its cost-effectiveness and scalability. Although it is the preferred synthesis method, it has several issues and challenges. Discussed in this dissertation are some of these issues as well as potential solutions. Physical and chemical properties of the co-precipitation product such as yield, particle size, morphology, and tap density, depend on various reaction parameters, which include pH, chelating agents, metal salt concentrations, and stirring speed. In the …

Voltage Control Of Interfacial Magnetism For Energy-Efficient Skyrmion-Based Memory And Neuromorphic Computing, Md Mahadi Rajib

Theses and Dissertations

The data generated annually has reached unprecedented levels, necessitating the integration of energy-efficient computing systems to achieve high performance and sustain our society’s computing needs. Specifically, energy-efficient computing, once considered advantageous, has now become essential in managing this exponential data growth. For example, the energy used solely by Google was equivalent to the energy consumed by a country with population >20 million in 2019 and this energy need is increasing exponentially [1]. Therefore, high-performance computing systems with energy-efficient, faster operability, and scalable computing units are necessary to address present and future computing challenges.

Apart from traditionally used conventional von Neumann …

Mild Traumatic Brain Injury In Yucatan Minipigs: Assessing Changes In Approachability And Mechanical Nociception Following Diffuse Central Fluid Percussion Injury, Mark D. Pavlichenko

Theses and Dissertations

Traumatic brain injury (TBI) is a major healthcare concern affecting millions. Symptoms of TBI include sensory sensitivity and social changes that may persist long-term. Due to similarities in cytoarchitecture, metabolism, and inflammation, higher order minipig models are advantageous for translational TBI research, however, there remains a shortage of information regarding their behavioral and sensory sequelae following injury. Therefore, in this study, we assessed changes in sociability and somatosensation in adult male and female Yucatan minipigs for up to one-week following a sham or central fluid percussion injury (cFPI). Specifically, the voluntary human approach task (VHAT) and the forced human approach …

Supported Metal Nanoparticle Synthesis: Precursor Deposition And Agglomeration At Support Surfaces, Edward H. Chandler Jr.

Theses and Dissertations

Catalysis is a critical component of the chemical manufacturing industry. For example, it has been estimated to be essential to more than 90% of the major industrial processes developed during the middle years of the 20^th century.¹ Heterogeneously supported transition metal catalysts in particular have many benefits such as easy separability from the reaction mixture and high thermal stability. One method of synthesizing these is wet impregnation, wherein a metal solution is brought into contact with an oxide- or carbon-based powder. Given optimal environmental conditions, a metal will adhere to the surface through electrostatic means in a process …

Mathematical Modeling Of Phage-Bacteria Population Dynamics, John Lawrence D. Palacios

Theses and Dissertations

Bacteriophages are viruses that infect and replicate within bacteria. Lytic phages cause the bacterial cell to burst, killing the bacteria. These types of phages can be used to treat patients with antibiotic-resistant bacterial infections. As a step in developing successful treatment protocols, we aim to understand the population dynamics of phages and bacteria using an in vitro model. We model the dynamics using the Campbell model, which consists of a delay differential equation (DDE), as a base model. We extended the model by including the emergence of phage resistance. We then compared the DDE model with a parallel ordinary differential …

Applying X-Ray Fluorescence With Monte Carlo Methods For Analysis Of Surface Defects On Coated Zr4, James Tyler Cahill

Theses and Dissertations

Chromium-coated Zircaloy-4 cladding represents a novel solution for creating nuclear cladding that has passive safety features. This and related developments aimed at improving nuclear safety are broadly categorized as accident-tolerant fuel and cladding. However, implementing this material presents practical challenges such as the vulnerability that cladding has to surface damage such as fretting wear. This research aims to determine if the pre-existing technique of X-ray fluorescence analysis is applicable for detecting these defects on the surface of the cladding. This was done by developing Monte Carlo N-Particle Transport models of a handheld device, the XL-5, alongside experimental measurements using this …

Machine Learning Assisted Optimization For Calculation And Automated Tuning Of Antennas, Lauren Linkous

Theses and Dissertations

The Antenna Calculation and Autotuning Tool (AntennaCAT) software suite represents a significant advancement in the field of antenna design by automating the entire design, CAD, simulation, and optimization process compatible with several EM simulation software suites. It is the first comprehensive implementation of machine learning in this context. In particular, this work includes the capability to create and export structured datasets from the aforementioned EM software for iterative improvement and includes an expandable selection of optimizers.

T Cell Polarization Regulates The Inflammatory Response And Tissue Regeneration At The Peri-Implant Interface, Derek Avery

Theses and Dissertations

Unresolved healing and localized chronic inflammation are common occurrences after biomaterial implantation, resulting in unfavorable clinical outcomes such as implant failure or fibrous encapsulation. T cells are adaptive immune cells found in lymph nodes, thymus, spleen, bone marrow, and around biomaterials, significantly impacting the degree of inflammation and wound healing. T cells are vital for inflammatory cytokine production and modulation of innate immune cells, including neutrophils and macrophages. T cells can be differentiated into two primary subsets, CD4⁺ and CD8⁺ T cells, playing distinctive roles in various pathologies and disease states. While T cells have been characterized well …

Re-Programming Transcription Factor Function For Neuroscience Research Of Addiction: Investigating The Role Of Zinc Finger Proteins In Driving Cocaine Reinforcement In Mice, Joseph A. Picone

Theses and Dissertations

Administration of addictive drugs like cocaine or morphine initiates aberrant gene transcription within brain reward circuitry neurons, which contributes to the lasting behavioral maladaptations that define addiction. The drug-induced expression and function of key brain transcription factors (TFs) is one major mechanism through which these drugs are able to regulate transcription, and as a consequence, lasting damaging drug-related behaviors including compulsive drug use. The goal of this dissertation is to more fully understand the molecular mechanistic drug-specific actions of TFs within the rodent nucleus accumbens (NAc). The findings from these studies could serve as the basis to identify novel candidate …

Using Asset-Based Community Development To Increase Student Engagement And Improve Student Experience In Schools, Jacqueline Hopkins

Theses and Dissertations

The following is a dissertation in the three-paper dissertation format. The first section will give background information on the issue of alienation in schools and how asset-based community development (ABCD) could be an effective tool for educators to combat alienation and disengagement, especially with students with marginalized identities. This first section will also show the significance of the three papers as a whole and how they connect to one another. The first paper is the conceptual literature review, the second paper is an empirical study of the ABCD model in schools, and the dissertation will end with a practitioner's article …

Temporal Discrimination Of Lucilia Sericata Pupae Using Dart- Tof-Ms And Statistical Analysis, Nguyen-Khoa N. Pham

Master of Science in Forensic Science Directed Research Projects

Lucilia sericata (Diptera: Calliphoridae) is a forensically important blow fly species. These flies have been extensively studied as they are one of the earliest colonizers of corpses. Adult females blow flies lay approximately 200-2,300 eggs, which upon hatching will feed off the body as they metamorphosize from first to second, and third instars. The third instar larvae then migrate away from the body in a stage known as pre-pupa, and develop into the puparial stage. The adults emerge from the pupa stage, leaving behind their empty puparium. These developmental stages are used by forensic entomologists to determine a minimum postmortem …

Further Optimization Of A Simplified Protocol For Tooth Sample Preparation For Analysis Using The Applied Biosystems™ Rapidhit™ Id Instrument, Yen H. Dang

Master of Science in Forensic Science Directed Research Projects

Due to the destructive nature of mass casualty incidents (MCIs) or mass fatality events (MFEs), tooth samples are often one of the only viable sources for Disaster Victim Identification (DVI) because of the incredible integrity of the enamel layer surrounding the tooth. However, the resilient structure of the tooth requires harsh chemicals and a labor-intensive sample preparation protocol to ensure successful STR profile development. Considering this difficulty, one of the promising resolutions is the Applied Biosystems RapidHIT™ ID ID platform, which is a fully automated system that is designed to perform cell lysis, DNA isolation, polymerase chain reaction (PCR) amplification, …

The Many Impacts Of The Covid-19 Pandemic On Latinx College Students’ Mental Health: Exploring The Role Of Sleep, Social Support, And Familismo, Mayra S. Ramos

Theses and Dissertations

College students experienced a multitude of disruptions to their daily life, and changes to their physical (i.e., sleep quality) and mental health (e.g., anxiety and depressive symptoms) because of the COVID-19 pandemic. Though the field has identified the factors that have contributed to negative physical and mental health changes, there remains much to be known about social and cultural protective factors that could buffer the negative role of the COVID-19 pandemic on Latinx college students. The current study contributed to the literature on the mental health outcomes of Latinx college students by identifying a possible mediator and moderators between the …

Trait Mindfulness And Political Polarization: Investigating Neural Responses And Emotional Orientations, Elif Z. Celik

Theses and Dissertations

The rapid escalation of political polarization has led to increased social distancing, aggressive partisan behavior, and discriminatory attitudes among Democrats and Republicans. Prior research has indicated that mindfulness is associated with increased compassion, reduced prejudice, and diminished aggression toward out-group members. This thesis investigates the relationship between trait mindfulness and political polarization by examining neural responses and emotional orientations in individuals with varying levels of mindfulness. This research measured brain activity using functional near-infrared spectroscopy (fNIRS) while participants viewed emotionally charged political videos and neutral content. The primary hypothesis suggested that individuals with high trait mindfulness would exhibit left-lateralized prefrontal …

Effect Of Annealing On Photoluminescence From Defects In Gan, Oleksandr Andrieiev

Theses and Dissertations

Annealing is a critical process in modern GaN technology, essential for achieving p-type conductivity by activating the Mg_Ga acceptor, as first demonstrated by Shuji Nakamura in the early 1990s. Despite the omnipresence of hydrogen as an impurity in GaN crystals, the precise mechanisms governing hydrogen diffusion and acceptor passivation remain only partially understood. The presented research investigates the effects of annealing-induced activation and hydrogen passivation on C and Be acceptors in GaN grown by MOCVD, HVPE, and MBE methods. We explored these effects by using several annealing techniques, gas compositions, and thermal regimes. A transient behavior between the C …

Evaluation Of Alternative Methods For Dna Recovery Of Compromised Skeletal Remains, Ciara N. Rhodes

Theses and Dissertations

Skeletal remains frequently serve as the sole source of genetic material available for developing a profile in cases concerning unidentified human remains or mass casualties. Nevertheless, as unidentified skeletal remains age and are exposed to uncontrolled environmental conditions, the success rates of conventional methods of bone analysis diminish significantly. The physical and mechanical processing of skeletal remains into fine powder for DNA isolation and downstream analysis can substantially impact the quality and quantity of recoverable genetic information. This concern may be exacerbated when dealing with degraded forensic skeletal remains. Few studies have explored whether pulverization of bone samples contributes to …

Title: I: L1-Norm Matrix Completion For Recommender Systems Ii: Conjecturing-Based Classification, Fatemeh Valizadeh Gamchi

Theses and Dissertations

Recommendation systems are essential for providing personalized user experiences, but their performance can be affected by outliers especially in traditional collaborative filtering methods that use the L2-norm. To address this challenge, we developed two new algorithms, SharpEl1rs and SharpEl1rs-Impute, based on the L1-norm to improve resistance against extreme values and effectively handle missing data. Our experimental setting was designed to compare these proposed methods with existing techniques. Then our algorithms are applied to real datasets to assess their performance, with findings indicating that our proposed models offer improved accuracy in some cases and solid performance in others for industrial-scale recommendation …

“You Are Not Obligated To Complete The Work, But Neither Are You Free To Desist From It.” Richmond Jews In Social Activism Post Civil Rights, Tracy S. Herman

Theses and Dissertations

For centuries, the Jewish people have faced expulsions, pogroms, massacres, and Propaganda. that runs so deep it would be like staring into an abyss. This oppression has motivated Jewish activists worldwide to fight back not only on behalf of the Jewish community but for many areas of perceived need. Jewish involvement in social activism in the U.S. has been particularly recognized by scholars of the labor and Civil Rights movements. This thesis is based on eighteen oral history interviews focused on social activism in Richmond, Virginia since the Civil Rights era. The author conducted these interviews in 2021, 2023, and …

Polyvictimization In Context: Identifying Patterns Of Peer, Dating, And Community Violence Among Black Early Adolescents, Carine Leslie

Theses and Dissertations

Early adolescents exposed to multiple forms of victimization (“polyvictimization”) may experience a number of detrimental psychosocial outcomes. Some person-centered research has identified victimization subgroups among adolescents but have not examined the overlap of peer, dating, and community victimization among Black early adolescents living in economically disadvantaged urban communities. Thus, this study empirically identifies victimization profiles in a sample of Black early adolescents to ascertain the patterns and correlates of polyvictimization. The present study aimed to (a) identify subgroups of Black early adolescents based on their frequency of peer, dating, and community victimization using latent profile analyses, and (b) evaluate the …

Considering Systems Of Power And Black And Latine Students’ Belonging In Stem, Korinthia D. Nicolai

Theses and Dissertations

This dissertation focuses on (a) exploring the need for and strategies to facilitate the integration of Critical Race Theory (CRT) and educational psychology and (b) supporting Black and Latine students through examining the impact of systems of power via the integration of belonging and Critical Race Theory. This dissertation follows a three-paper format. In Paper 1, we recognize that psychology researchers can use CRT to explore race and racism. However, psychology scholars may confront growing pains when integrating CRT due to their respective inquiry worldviews–postpositivism and critical–which result in several tensions. These tensions may limit the uptake of CRT in …

Call For Me When You Get There: I'Ll Be Among The Crows, Jessica O. Tifase

Theses and Dissertations

I've always been intrigued by the ways in which the notion of flight has been used to describe the movement of Black people, both literally and figuratively. In many instances, flight performs as a double entendre, embodying multiple meanings: to escape or to transcend. The fluidity of its definition prompts a reflection I’ve been wrestling with as I move through the world: Are Black people in a perpetual state of flight?

In my thesis exhibition, Call for Me When You Get There, I use the precarious state of flight as a means to explore the complicated choreography necessary for navigating …

Trends, Challenges, And Evidence-Based Strategies For School Dropout Prevention In Virginia, David B. Naff, Thea Racelis, Regina Frazier, Meleah Ellison, Christina Tillery, Andy Bristow, Audra P. Lancaster, Sabrina Evans, Leah Wiedenhoft, Dina Abdul Rahman, Sharrie Merritte, Karli Johansen, Sooyeon Moon, Jean Samuel, Tara Davison

MERC Publications

This MERC research and policy brief explores school dropout prevention by focusing on recent trends and research. It addresses the following questions:

1) What are recent trends in school dropout?
2) What factors contribute to school dropout?
3) What are the consequences and implications of school dropout?
4) What are evidence-based strategies for school dropout prevention?
5) What are federal, state, and division-level policies related to school dropout prevention in the MERC region?

It concludes with a series of key takeaways and recommendations.

I Am Who I Am, Yifei Kong

Theses and Dissertations

I am Who I am

By Yifei Kong, MFA

My thesis research focuses on my cultural background and history as a Chinese woman. I explore the control and restraint of women from ancient times and highlight feminism. Traditional Chinese hair accessories reflect a type of control over women. Unlike traditional Chinese hair accessories, which use a lot of precious metals and precious stones, my work uses recycled aluminum cans. That is an exploration of contemporary jewelry materials and a reflection of women's independent right to choose. With my pieces, women can use their preferred colors without considering their class and …

Frozen By Worry And Fatigue? A Mixed Methods Approach To Understanding The Lived Experiences Of Freezing Of Gait, Sarah M. Ghose

Theses and Dissertations

This study utilized a mixed methods emergent, phenomenological approach to (1) understanding the lived experience of freezing of gait for individuals diagnosed with Parkinson’s Disease and (2) determining the role of anxiety and sleep in freezing of gait outcomes. Participants included 13 adults diagnosed with Parkinson’s Disease (N=14 for qualitative data, N=13 for quantitative data; 23.1% female-identifying, 76.9% male-identifying) who were predominantly white (92.3%) with an average age of 69 years (SD = 6.73 years). Data collection consisted of semi-structured interviews, self-report measures, actigraphic sleep data, and salivary alpha amylase biomarker collection. Results are organized into …