Digital Commons Network^™

Stochastic Decision Modeling To Improve Breast Cancer Preventive Care, Sevda Molani

Doctoral Dissertations

Breast cancer is a leading cause of premature mortality among women in the United States. Breast cancer screening tests can help with detecting breast cancer in early stages and thereby reducing the breast cancer mortality risk. However, due to the imperfect nature of screening tests, there is always some associated overdiagnosis, false positives, and false negatives risks. Therefore, to improve breast cancer preventive care, we defined the focus of this dissertation on modeling breast cancer screening decisions.

Breast cancer overdiagnosis is the first issue that is addressed in this dissertation. Although overdiagnosis is known to be the major risk inherent …

The Natural Potential Of Transition Metals To Activate The Initial Steps Of Fischer-Tropsch Catalysis: A Dft Study, Sumegha Godara

Doctoral Dissertations

With recent advances in modeling and simulations methods along with state-of-the- art supercomputers, theoretical studies are becoming a cheaper choice for scientific predictions and provide complementary support to the experiments. Intense research in catalysis has been done in the past two decades experimentally as well as theoretically. This works employs first-principle studies to predict the most promising catalysts for Fischer-Tropsch (FT) reaction based on size and composition. The transition metals Fe, Co, Ni, Ru, Pd, and Pt, have been explored in pure and alloyed nanocluster forms for the effectiveness of catalytic properties.

The first and most crucial step of the …

Fused Deposition Modeling Of Perovskite Solar Cell Active Layer With Integrated Thermal Management, Tyler Sonsalla

Doctoral Dissertations

Fossil fuel usage has been our primary form of energy used to fabricate and give us many of the products and services that we use today. However, our fossil fuel usage has led to an increase in the release of greenhouse gases. Greenhouse gases affect the global surface temperatures of our planet, which can reduce our ability to produce crops, lead to stronger and more frequent natural disasters, and change the acidity of our oceans. To combat this problem, new energy harvesting techniques and technologies are required to reduce our reliance on fossil fuels.

One solution to reducing our reliance …

The Influence Of Online Product Recommendations On Consumer Choice-Making Confidence, Effort, And Satisfaction, Mohammad Amin Saleh

Doctoral Dissertations

The number of products and services available online is growing at a tremendous pace. Consumers increasingly desire the ability to filter through the noise and quickly discover the products that are most relevant to their needs. Many businesses are implementing product recommender systems to provide this ability to consumers, and the result is often increased sales and more satisfied customers.

However, recommender systems can also have negative consequences for consumers. For example, a recommender system can bias consumers to purchase more expensive products. Additionally, theories of consumer choice-making suggest that recommender systems can sometimes make purchase choices more difficult, resulting …

Quantum Corrections To The Electromagnetic Response Of Conducting Nanostructures, Neal Blackman

Doctoral Dissertations

The electromagnetic response of conducting nanostructures in the 1 to 10 nm size range is investigated using the quantum box model (QBM). The core purpose of this dissertation is to understand how quantum effects emerge in both the electric and magnetic response of nanostructures in this size range, and in particular, explore how these effects can improve the design of future technology in the fields of plasmonics, metamaterials, and nano-composite materials. One of the primary objectives is to study how quantum effects enhance magnetism in nanoconductors and determine whether quantum resonances give rise to negative permeability, a highly desirable property …

Zinc Oxide Based Nanowire Arrays For Selective Detection Of Multiple Gaseous Analytes At Elevated Temperature, Bo Zhang

Doctoral Dissertations

Zinc oxide (ZnO) based nanostructures represent an important class of gas sensor materials, due to their high surface-to-volume ratio, significant surface band structure bending upon gaseous analyte exposures, good mobility of charge carriers, and good structural stability at elevated temperature. Their usually surface-dominant sensing processes entail the important roles played by nanostructure size, defects, morphologies, and surface absorbate energetics and dynamics. In this dissertation, based on ZnO nanowire array as a gas sensing platform, rational decoration of electronic sensitizers, such as Au nanoparticles, and semiconducting oxide, such as Fe₂O₃ nanoparticles, has been employed to boost its electrical …

Distributed Cooperative Control Of Multi-Agent Systems Under Detectability And Communication Constraints, Himadri Basu

Doctoral Dissertations

Cooperative control of multi-agent systems has recently gained widespread attention from the scientific communities due to numerous applications in areas such as the formation control in unmanned vehicles, cooperative attitude control of spacecrafts, clustering of micro-satellites, environmental monitoring and exploration by mobile sensor networks, etc. The primary goal of a cooperative control problem for multi-agent systems is to design a decentralized control algorithm for each agent, relying on the local coordination of their actions to exhibit a collective behavior. Common challenges encountered in the study of cooperative control problems are unavailable group-level information, and limited bandwidth of the shared communication. …

Effects Of Nearshore Processes On Carbonate Chemistry Dynamics And Ocean Acidification, Melissa Melendez

Doctoral Dissertations

Time series from open ocean fixed stations have robustly documented secular changes in carbonate chemistry and long-term ocean acidification (OA) trends as a direct response to increases in atmospheric carbon dioxide (CO2). However, few high-frequency coastal carbon time series are available in reef systems, where most affected tropical marine organisms reside. Seasonal variations in carbonate chemistry at Cheeca Rocks (CR), Florida, and La Parguera (LP), Puerto Rico, are presented based on 8 and 10 years of continuous, high-quality measurements, respectively. This dissertation synthesizes autonomous and bottle observations to model carbonate chemistry and to understand how physical and biological processes affect …

Experiments And Modeling Of Plastic Anisotropy And Ductile Fracture Under Multiaxial Loading, Madhav Baral

Doctoral Dissertations

The implementation of new materials for light-weighting purposes in the automotive industry has often been hindered due to the low ductility of these materials, as well as inadequate empirical knowledge about their fracture behavior and inadequate material modeling techniques. This thesis addresses these issues through extensive experimental and numerical study of plastic anisotropy and ductile fracture of several aluminum alloys and a stainless-steel. The test materials used for this study include AA365 die-casting, AA6013 and AA6111 aluminum sheets, AA6260 aluminum tube and SS304L stainless-steel microtube. The plastic anisotropy is assessed using uniaxial tension, plane-strain tension and disc compression experiments for …

Essays On Macroeconomic Uncertainty: New Evidence From China, Meng Yan

Doctoral Dissertations

This dissertation is a collection of three essays about uncertainty and conducts a country-specific study based on China.

In Chapter 1, I investigate the impact of US uncertainty shocks on China's macroeconomy with a focus on the dynamic response of investment. Using a structural vector autoregression model, I find that the wait-and-see mechanism of aggregate investment in the face of heightened US uncertainty disappears in China. Robust evidence confirms that the increase in state-owned enterprises' investment in response to heightened uncertainty explains this puzzle, while private-owned enterprises' investment decreases as expected. I apply regime-dependent local projections to link uncertainty shocks …

Evaluation And Identification Of Cracking Susceptibility Of Asphalt Binders And Mixtures By Incorporation Of Effects Of Aging On Performance, Runhua Zhang

Doctoral Dissertations

An important aspect which causes a significant effect on performance of asphalt materials is aging. With increase of aging, asphalt materials lose their relaxation capabilities and becomes more susceptible to cracking. Thus, an improved understanding of how aging impacts the cracking behavior of asphalt materials will allow for design of more reliable and durable asphalt pavements. In this study, different laboratory aging levels were performed to simulate different periods of pavement service life. Various performance tests (including Complex Modulus (E*), Simplified Viscoelastic Continuum Damage (S-VECD), Semi Circular Bending (SCB) and Disk Shaped Compact Tension (DCT) tests for asphalt mixtures; Frequency …

Nutrient Cycling Along Microbial And Lithologic Gradients And Fostering Student Self-Confidence In Science, Kiley Remiszewski

Doctoral Dissertations

Increased understanding of the impact of biology on weathering rates and its response to environmental factors will lead to more accurate global models and enhanced management practices to optimize productive, healthy forests. Although biological contributions to weathering are established in the literature, more data to translate these observations for implementation in a predictive framework should be obtained (e.g. Taylor et al., 2012). Mycorrhizal fungi have implications for global carbon cycling and increasing carbon storage in soils (Soudzilovskaia et al., 2019) but the extent of their impact is still an area of active research with more studies of local weathering sites …

The Trophic Ecology Of Coral Reef Sponges In Caribbean Mesophotic Ecosystems, Keir John Macartney

Doctoral Dissertations

Emergent sponges are crucial to the functional ecology of coral reef ecosystems, playing key roles in benthic-pelagic coupling, biogeochemical cycling of key nutrients, and provision of food and habitat to a variety of coral reef fauna. In mesophotic coral reef ecosystems (MCEs), sponges show a repeatable pattern of increasing abundance and diversity with increasing depth. Mesophotic coral reef ecosystems are typically found between 30 – 150 m and are characterized by depth-dependent gradients in photosynthetically active radiation (PAR), and trophic resources such as increases in particulate organic matter (POM) and decreases in dissolved organic matter (DOM). Increased concentrations of POM …

Dynamic Performance Of Partially Saturated And Unsaturated Soils, Sayedmasoud Mousavi

Doctoral Dissertations

The vast majority of surface structures are located on or surrounded by unsaturated and partially saturated soil deposits. Previous studies revealed that degree of saturation in soils can significantly impact the seismic performance of geotechnical systems. Yet, the fundamental understanding of the mechanisms by which the degree of saturation impacts their performance during seismic loading is not mature. This Ph.D. dissertation aimed to evaluate and characterize the dynamic response of soils including excess pore pressure generation, induced volumetric deformation, shear modulus, and material damping at different states of saturation and a wide range of degrees of saturation. Three different desaturation …

In-Situ Cryogenic Mechanical Characterization Of Materials At Micrometer Scales, Gyuho Song

Doctoral Dissertations

The mechanical properties of materials have been considered as one of the most important material properties for the development of mechanically reliable engineering products. Although some materials exhibit excellent material properties, such as electronic, magnetic, thermal, and optical properties, the materials cannot be usable in engineering applications if they are mechanically unstable in devices. Nowadays, nanotechnology allows us to make useful small-scale engineering devices, for instance, actuators of Micro-Electro-Mechanical-Systems and silicon-based electronic devices. These developments have continuously required the creation of mechanically reliable small materials that can survive during the long-term service. For the last two decades, micromechanical studies have …

Mitigation Of Air-Electrode Degradation In High-Temperature Electrochemical Systems: Capture Of Airborne Contaminants By Getters, Junsung Hong

Doctoral Dissertations

High-temperature electrochemical devices including solid oxide fuel cells (SOFC) have been recognized as promising candidates for next-generation devices for energy conversion, storage, and gas separation. These devices, however, remain susceptible to the electrocatalytic poisoning of air-electrodes from trace airborne contaminants such as Cr/Si/B vapors, SO₂, CO₂, and water species. The long-term exposure of air-electrodes to air flow at high operating temperatures leads to the accumulation of airborne gas impurities, and the formation of undesired compounds, degrading the electrochemical catalytic activity of air-electrodes. To date, most efforts to mitigate the electrode poisoning have focused on developing low-temperature/impurity-tolerant …

Adaptive Trust Negotiation For Time-Critical Access To Sensitive Data, Eugene Sanzi

Doctoral Dissertations

The security of an application’s data is an important consideration when creating modern applications. Users requiring secure data access undergo an explicit pre-registration process where an electronic identity (username, X.509 certificate, etc.) and a method of laying claim to the identity (password, public/private key pair, etc.) are created. The user’s authorization data is associated with the electronic identity. However, there are emergent situations where a user needs to access data where previous pre-registration is not possible because the future need for such data is unpredictable, such as an emergency room physician accessing the electronic health records (EHRs) of admitted patients. …

Dynamic Network Configurations For Functionality And Security, Devon Callahan

Doctoral Dissertations

Networks are designed with functionality, security, performance, and cost in mind. Flows should be served while controlling risk due to attackers. Configuration is time intensive and largely static until a major new vulnerability or service requirement forces change. We address this problem with an autonomous framework consisting of Observe, Orient, Decide and Act phases and look to optimization techniques for solutions to the Orient and Decide phases.

Our first solution explores opportunities to improve network Quality of Service by combining a single flow routing solutions with a global multi-flow solution in a hybrid manner. In order to evaluate the quality …

Intimate Partner Violence Screening Among Barbadian Primary Care Professionals: An Exploratory Study Of Practitioner Attitudes, Beliefs, Knowledge And Screening Intention, Janelle Bryan

Doctoral Dissertations

Intimate Partner Violence (IPV), the most prevalent type of violence against women, has been recognized as a human rights violation by intergovernmental organizations and international law. Due to its physical and psychological sequelae, the World Health Organization has considered IPV a major global public health issue since 1997. Primary care health care professionals (HCPs) are considered especially well-positioned to identify women experiencing IPV, yet screening rates are low. Utilizing the Integrated Behavioral Model (IBM) and Intersectional Feminism as guiding theoretical frames, this mixed method study (qualitative, N = 35; quantitative, N = 176) explored Barbadian HCPs’ attitudes, beliefs and knowledge …

Characterization Of The Biogeography And Temporal Dynamics Of The Trachymyrmex Septentrionalis Fungus Garden Microbiome, Kevin Lee

Doctoral Dissertations

Like all fungus-growing ants, Trachymyrmex septentrionalis engages in an obligate mutualism with a Basidiomycete fungus that it raises as its primary nutrition source. Therefore, the success of the symbiosis is dependent upon the health of the fungus garden containing this fungus, which may be affected by the composition of its microbiome. Most of what is known about fungus garden microbiomes comes from studies of the Neotropical fungus growing ants, especially the most evolutionarily derived and economically impactful “leaf-cutting” species. Although fungus-farming ants inhabit a vast range, little is known about how dispersal of microbes from their biogeographically and temporally distinct …

Shadow Detection And Classification In High-Resolution Aerial Imagery, Qian Lei

Doctoral Dissertations

High-resolution imagery is becoming increasingly available for use in land-cover mapping; however, previous studies have found that urban shadows cast by elevated features in urban environments can cause substantial errors in land-cover classifications. Detecting and restoring land-cover information within urban shadows can help improve accuracy in land-cover mapping. Although a considerable number of studies have been conducted on both shadow detection and shadow restoration, few studies have focused on a complete urban shadow correction workflow that combines shadow detection and restoration for the purpose of land-cover mapping using high-resolution aerial imagery across large geographic extents s. Thus, the goal of …

Enzyme-Responsive Nucleic Acid Nanocapsules (Nans) For The Delivery Of Therapeutic Oligonucleotides And Small Molecule Drugs, Alyssa Hartmann

Doctoral Dissertations

The first chapter of this work describes a novel, enzyme-responsive nanocapsule for the intracellular delivery of therapeutic nucleic acids and small molecule drugs. The stepwise assembly of this new construct, referred to as a nucleic acid nanocapsule (NAN), is presented. The cellular uptake properties of the NAN are investigated through confocal microscopy. Additionally, the functionalization of the NAN with a therapeutic nucleic acid is described. For these experiments, the NAN was functionalized with a DNAzyme, a catalytically active DNA molecule that can specifically bind and cleave a target mRNA sequence. The DNAzyme utilized in these studies is specific for the …

End-To-End Structure-Aware Convolutional Networks On Graphs, Chao Shang

Doctoral Dissertations

Convolutional neural networks (CNNs) are powerful tools to model data of a grid-like structure, such as image, video, and speech. However, a broad range of scientific problems generate data that naturally lie in irregular grids with non-Euclidean metrics, such as knowledge graphs, molecular graphs, and traffic networks. The generalization of CNNs to non-Euclidean structured data such as graphs is not straightforward. The classical convolutions cannot be applied directly to graphs, due to the lack of global parameterization, a common system of coordinates, and shift-invariance properties. In this dissertation, we propose several structure-aware convolutional neural network models to calculate graph convolutions …

Temporal Modeling Frameworks For Coastal Wave Heights, Ellis Shaffer

Doctoral Dissertations

Current marine science methods for modeling wave data typically assume that wave height distributions belong to limited class within the exponential family. Alternatively, models emphasize physics principles over statistical methods. In this dissertation, we investigate the predictive power of wave height histories as well as exogenous predictors. We develop binary time series models for wave height over a threshold in both frequentist and Bayesian frameworks. Within the Bayesian framework, we fit Dynamic Generalized Linear Models (DGLM) using Integrated Nested Laplace Approximations and demonstrate advantages over classical methods. We further investigate the quantiles and expectiles of the continuous- valued wave height …

Nanostructured Flame Retardant Coatings, Brandon Williams

Doctoral Dissertations

Fires account for approximately 3100 deaths and $10 billion in property damage annually in the US. Growing consumption of polymeric materials increases the potential damage a fire could cause. Halogenated chemicals have dominated as the primary means of flame retarding (FR) polymeric materials since the 1960s. However, regulation has required they be phased out of use, directing research towards halogen-free FR solutions. One emerging technology is nanocoatings. Nanocoatings are currently processed using direct mixing, in situ polymerization, and layer-by-layer deposition in attempts to achieve well-organized and highly dispersed nanosheets. These processing methods are limited by efficiency and scalability. Recently a …

Predicting Materials Behavior With Atomistic Simulations And Machine Learning, Ayana Ghosh

Doctoral Dissertations

Data driven approaches based on machine learning (ML) algorithms are very popular in the domain of physical sciences for the determination of yet unknown structure- properties-performance relationships for a wide range of different material families. This dissertation focuses on studying a number of such cases where various ML algorithms and statistical techniques, coupled with appropriate materials data obtained from experiments and atomistic simulations, are employed to build comprehensive ML-based frameworks capable of predicting complex materials behavior. The materials spaces investigated encompass isolated organic molecules, polymer crystals, inorganic multiferroics and actinides, while the target system characteristics or functionalities include molecular crystallization …

The Role Of Extrinsic Motivators On Job Satisfaction And Turnover In Higher Education Within R2 Research Universities In The United States, Zachary James Harris

Doctoral Dissertations

The purpose of this study was to evaluate extrinsic motivators and the relationship they have with job satisfaction and turnover intent. Literature suggests that higher education faculty have differing needs and satisfiers than other public sector employees (Lee & Wilkins, 2011; Maidani, 1991). As a result, the Delphi method was utilized to identify extrinsic motivators that were tailored to higher education. Once these motivators were identified through a panel of experts, they were combined to create a survey with previously established scales measuring job satisfaction and turnover intent.

This survey was designed to answer the following research questions: 1) what …

A Normative Classification Of Consumer Big Data, Anuashine Chefor Ellis

Doctoral Dissertations

The big data phenomenon has transformed every area of life and business. Businesses today rely on the volume, velocity, and variety (3Vs) of data available today in product design, advertisement, sales, and post-sale follow up activities. Communication between the firm and the consumer is personalized using data collected on the consumer to match the consumer’s location, time, and needs. Some marketers argue that this has birth a new era of marketing; transformative marketing, in which the firm’s ability to deliver value and to acquire and maintain long-run competitive advantage determined by the firm’s data resources. In other words, data are …

An Instrumental Case Study For The Implementation Of Strategic Planning The College Of Education At A Select Southern University, Amber Burdge

Doctoral Dissertations

This qualitative study examined the implementation of the strategic plan in the College of Education at a select southern university. Among Higher Education Institutions (HEI), strategic planning has become one of the most fundamental factors of today’s education system as HEIs adjust to meet the calls of a knowledge-based global economy (Bakoğlu, Öncer, Yıldız, & Güllüoğlu, 2016). Raluca and Alecsandru (2012) claimed that HEIs should consistently find ways to remain applicable and competent in such a competitive market as the higher education system.

Failed or unfinished implementation of strategic plans in HEIs is prevalent (Fooladvand, Yarmohammadian, & Shahtalebi, 2015; Immordino, …

The Relationship Between Entrepreneurs' Identities, Passion, And Intention To Depart Their Ventures, Heather L. Budden

Doctoral Dissertations

A significant amount of Entrepreneurship literature has focused on both venture failure and the decision by entrepreneurs to leave or quit their businesses. A large portion of the literature has approached the topics of venture failure and the decision to leave or close companies from a financial perspective. While finances do play a vital role in entrepreneurs’ intentions to quit ventures, it is not the only variable impacting entrepreneurs’ decisions in regards to the continuation of their business ventures.

In this dissertation, antecedents of entrepreneurial identity centrality are investigated. Antecedents to the founder’s entrepreneurial identity centrality include entrepreneurial self-efficacy, lack …