An Empirical Comparison Of Machine Learning Models For Classification, Nubaira Rizvi

Theses and Dissertations

Classification problems are tackled across various industries throughout multiple disciplines. A model used for classification attempts to predict the class of an outcome variable based on some predictors. There are number of classification models available. But as the underlying population distribution of the predictors is always unknown it is difficult to know which model fits the situation best. Several studies have been done on which supervised model performs better given specific datasets. But little work has been done to compare the models’ performance for predicting one or more outcomes under multivariate settings.

This study compares the performance of seven popular …

The Analysis Of Neural Heterogeneity Through Mathematical And Statistical Methods, Kyle Wendling

Theses and Dissertations

Diversity of intrinsic neural attributes and network connections is known to exist in many areas of the brain and is thought to significantly affect neural coding. Recent theoretical and experimental work has argued that in uncoupled networks, coding is most accurate at intermediate levels of heterogeneity. I explore this phenomenon through two distinct approaches: a theoretical mathematical modeling approach and a data-driven statistical modeling approach.

Through the mathematical approach, I examine firing rate heterogeneity in a feedforward network of stochastic neural oscillators utilizing a high-dimensional model. The firing rate heterogeneity stems from two sources: intrinsic (different individual cells) and network …

The Relationship Between Access To School Counseling And Students’ Attainment And Persistence In Postsecondary And Stem Education Outcomes, Dana Brookover

Theses and Dissertations

School counselors design and implement comprehensive school counseling programs to support students’ academic, college and career, and personal/social development (ASCA, 2019). This includes the school counselor’s important role in college readiness counseling and science, technology, engineering, and math (STEM) counseling (Falco, 2017; Gilfillan, 2018). The current study focused on the relationships between access to school counseling and students’ long-term college readiness outcomes. Through a Social Cognitive Career Theory (SCCT; Lent et al., 1994) lens, two models to predict (1) college attainment and persistence and (2) STEM major attainment and persistence, were tested through logistic regression analyses. Additionally, this study also …

Sparsity And Weak Supervision In Quantum Machine Learning, Seyran Saeedi

Theses and Dissertations

Quantum computing is an interdisciplinary field at the intersection of computer science, mathematics, and physics that studies information processing tasks on a quantum computer. A quantum computer is a device whose operations are governed by the laws of quantum mechanics. As building quantum computers is nearing the era of commercialization and quantum supremacy, it is essential to think of potential applications that we might benefit from. Among many applications of quantum computation, one of the emerging fields is quantum machine learning. We focus on predictive models for binary classification and variants of Support Vector Machines that we expect to be …

Interpersonal Competency Configurations And The School Adjustment Of Early Adolescents With Disabilities: A Person-Centered Approach, Brittany I. Sterrett

Theses and Dissertations

The transition to middle school is a critical time in adolescence. The more complex school environment provides opportunities for growth and challenges for students with disabilities. Although special education strives to provide individualized supports to students with disabilities through data-based decision-making, the tools used to understand and meet the needs of these students are often unresponsive to the dynamic nature of development and student adjustment as they age. Grounded in developmental science, this study sought to create a data collection framework through a person-centered approach to inform the individualization process. Specifically, this study: 1) explored a decision process that allows …

On The Detection Of Gw190814, Matthew E. Gill

Theses and Dissertations

The eld of gravitational wave astronomy is currently at an all time high. The

rst half of the most recent observing run (April 1, 2019 - September 30, 2019) yielded

a total of 39 gravitational wave detections, including 13 from sources which had not

been identied by other astronomical observation methods before. This is three times

as many detections than were measured in the rst two observing runs combined.

In this paper, the design sensitivity decisions leading to this unprecedented rate of

detection are explored. In particular, we detail the nature of the LIGO and VIRGO

gravitational wave interferometers. One …

Integrated Multiple Adaptive Design Involving Sample Size Re-Estimation And (Covariate-Adjusted) Response-Adaptive Randomization For Continuous And Binary Outcomes, Christine M. Orndahl

Theses and Dissertations

Historically, clinical trials have been performed based on decisions made prior to the start of the trial. Adaptive designs have been developed to provide increased flexibility, allowing pre-specified changes to occur based on interim data. Each adaptive design addresses a unique pitfall of a non-adaptive design, such as minimizing the chance of an under- or over-powered study by utilizing interim data to update the sample size estimate (sample size re-estimation) or increasing the ethical benefit of a trial by allocating more participants to the better performing treatment group ([covariate-adjusted] response-adaptive randomization). Additional benefit is attainable by combining more than one …

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 …

A Longitudinal Study Of The Influence Of A Stem Career Planning Course And Perceived Stress On Career Search Self-Efficacy And Retention In Engineering Undergraduate Students, Autumn Randell

Theses and Dissertations

This study investigated a) the influence of a STEM career planning course on undergraduate engineering students’ career search self-efficacy, b) the influence of perceived stress on building students’ career search self-efficacy, and c) the relationship career search self-efficacy had in predicting students’ odds of persistence in an engineering major. The researcher analyzed students’ week 1, week 6, and week 14 scores of career search self-efficacy and perceived stress. Data were collected from the Spring 2019 and Fall 2019 cohorts of a STEM career planning. As a result, the analysis included (N = 286) undergraduate engineering students. Repeated measures multilevel …

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 …

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 …

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.

The Immediate And Persistent Effects Of Binge Ethanol Exposure On Myelin Protein Expression In Dba/2j Mice, Aminatta Z. Tejan-Kamara

Theses and Dissertations

Binge drinking is the most lethal of drinking patterns, responsible for 77% of all U.S. alcohol misuse costs. Adolescents have increased sensitivity to ethanol’s rewarding properties and decreased sensitivity to ethanol’s aversive effects likely allowing for their increased binge drinking, as compared to adults. Ethanol consumption during adolescent neurodevelopment can lead to immediate and lasting neurobiological-consequences. We have previously shown that adolescent intermittent binge ethanol exposure decreases myelin-related gene expression in DBA/2J mice. Here, we hypothesize intermittent binge ethanol exposure in adolescent DBA/2J mice will decrease myelin protein expression in the prefrontal cortex (PFC) immediately following binge ethanol and this …

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 …

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 …

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.

Detection Of Biomolecules Via Ocp Measurements Using Npg Electrodes, Borkat Ullah

Theses and Dissertations

In sensing application nanoporous gold (NPG) has attracted much attention. NPG is prepared by dealloying Au:Ag alloys. Characterization was done using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). In this work, the open circuit potential (OCP) of ferricyanide, cysteine, uric acid, and ascorbic acid was measured in phosphate buffer solution (PBS) and biofouling solution containing bovine serum albumin (BSA) at pH 7.4. OCP measurement has been hindered due to biofouling and surface passivation on the metal electrodes. By the use of the NPG electrodes, electrochemical activity can be maintained. From the OCP measurement of cysteine, …

Investigation Into The Reaction Profile Of A Bioinspired Nickel Complex, Denver Heitger

Theses and Dissertations

Metal complexes that can activate natural oxidants like H₂O₂ and O₂ have become a key research topic in many labs in hope of mimicking nature, by generating a bioinspired complex that can perform unique chemistry through green processes. To prepare the perfect catalyst, this has lead scientists to explore numerous avenues, including the use of both natural and artificial oxidants, to tease apart the reaction pathway taking place. A ligand system dear to the Lucas Lab (13-DOB) has been metalated with nickel, a cheap and earth abundant transition metal. Our bioinspired metal-(di)oxygen adducts can be formed …

Comparing Coastal Storm Impact To Decadal Change In Barrier Island Ecosystems, Philip A. Tuley

Theses and Dissertations

Highly dynamic coastal systems respond to disturbance events with a combination of topographic and vegetative changes. Sea level rise impacts on barrier islands have been quantified, but storm effects on vegetation are limited. Here we quantified barrier island vegetation change in response to an isolated storm event and compared to long-term periods. We hypothesized that disturbance-resisting areas with high woody vegetation cover and/or high foredune elevation would experience minimal transitions after a storm event, whereas disturbance-reinforcing areas with low vegetation cover and low foredune elevation would experience greater transitions between ecosystem states after a storm event. Patterns of dissonance were …

Synthesis And The Genetic Encoding Of Novel Lysine Post-Translational Modifications, Sahan A. Galbada Liyanage

Theses and Dissertations

Post-translational modifications (PTMs) play a significant role in regulating cell signaling and regulating the inner cellular environment. The study of PTMs and their primary biological functions is critical for the development of new medicines targeting the pathways and biomolecules responsible for the PTMs.

Previous studies revealed the direct coupling of the β -hydroxybutyryl lysine (K_BHB) modification with the gene expression. K_BHB in histone proteins links metabolism to epigenetics and gene expression and enables to study in-depth, how cell metabolism controls the gene expression and vice versa. Similar novel histone modification, K_Lac, attracts a special interest …

Probing Vibrational Wave Packets In Organophoshorous Molecules Using Femtosecond Time-Resolved Mass Spectrometry (Ftrms), Derrick Ampadu Boateng

Theses and Dissertations

The study of organophosphorus and nitroaromatic compounds is essential due to their suitability as models for understanding the dynamics of radiation induce damage to DNA sugar-phosphate backbone, and the detection of chemical warfare agents as well as nitroaromatic explosives (such as TNT). The ultrafast dynamics of these polyatomic radicals were studied using femtosecond time-resolved mass spectrometry (FTRMS), a versatile method that is capable of monitoring the ultrafast dynamics of rapid dissociation in the gas phase after the removal of an electron. The method uses a technique called pump-probe, which makes use of two time-delayed laser pulses. In this work, the …

Quantification And Modeling Of Bladder Biomechanics Mechanisms Linking Spontaneous Rhythmic Contractions And Dynamic Elasticity To Detrusor Overactivity, Zachary E. Cullingsworth

Theses and Dissertations

Overactive bladder (OAB) is a chronic condition affecting approximately 20% of adults in the United States. Detrusor overactivity (DO) is the presence of non-voiding contractions in the detrusor (bladder) muscle during filling and is present in some individuals with OAB. DO is currently identified visually during a urodynamics (UD) study involving pressure catheters and filling and voiding of the bladder to evaluate function. UD provides limited subtyping of DO, and an incomplete understanding of mechanisms contributing to OAB.

Aim 1 of this study was to develop objective tools to quantify, subgroup and better understand …

Utilizing Design Structure For Improving Design Selection And Analysis, Ahlam Ali Alzharani

Theses and Dissertations

Recent work has shown that the structure for design plays a role in the simplicity or complexity of data analysis. To increase the knowledge of research in these areas, this dissertation aims to utilize design structure for improving design selection and analysis. In this regard, minimal dependent sets and block diagonal structure are both important concepts that are relevant to the orthogonality of the columns of a design. We are interested in finding ways to improve the data analysis especially for active effect detection by utilizing minimal dependent sets and block diagonal structure for design.

We introduce a new classification …

Pseudo-Data Generation For Improving Clinical Named Entity Recognition, Jeffrey T. Smith

Theses and Dissertations

One of the primary challenges for clinical Named Entity Recognition (NER) is the availability of annotated training data. Technical and legal hurdles prevent the creation and release of corpora related to electronic health records (EHRs). In this work, we look at the imapct of pseudo-data generation on clinical NER using gazetteering and thresholding utilizing a neural network model. We report that gazetteers can result in the inclusion of proper terms with the exclusion of determiners and pronouns in preceding and middle positions. Gazetteers that had higher numbers of terms inclusive to the original dataset had a higher impact. We also …

Towards A Greener Route To Blockbuster Statin Drugs: Harnessing The Power Of Biocatalysis And Integrating Cross-Coupling Catalysis In The Synthesis Of Rosuvastatin, Chanaka M. Amarasekarage

Theses and Dissertations

As global and political awareness about green and sustainable practices sharpens in the face of dramatic climate change and environmentally detrimental practices, one attractive approach is to harness the catalytic potential of enzymes. Thus influenced, our efforts focused on the development of an innovative chemoenzymatic route to widely prescribed Blockbuster statin drugs, specifically rosuvastatin. In this work, we engineered novel deoxyribose phosphate aldolase (DERA) variants via rationally designed site-directed mutagenesis to accept non-natural, less polar substrate, acrolein, along with acetaldehyde. Several of new mutants displayed elevated tolerance towards aldehydes and showed effective incorporation of acrolein into the unprecedented enzymatically-derived chiral …