Physical Sciences and Mathematics Commons^™

Bayesian Calibration Of The Icrp Zirconium Biokinetic Model And Use Of Canned Priors For The Evaluation Of Bioassay, Thomas Raymond Labone

Theses and Dissertations

The International Commission on Radiological Protection (ICRP) publishes biokinetic models that relate measurements of radioactive material in the body and excreta (bioassay) to the amount of the material taken into the body (intake). Given the intake and the biokinetic model, radiation dose to organs and tissues can be calculated. The ICRP approximates the biokinetics of radioactive materials in the body with compartmental models expressed mathematically as a system of ordinary differential equations, for which they provide point estimates of the rate constants. Inaccurate estimates of intake and radiation dose can result in cases where the biokinetics of an individual differ …

Land, Racial Formations, And Power: Exploring The Network Of Power Relationships During Climate Change Planning In Coastal South Carolina, Teresa Norman

Theses and Dissertations

Climate change projections for the coastline of South Carolina predict that by mid-century there will be around 1.2 feet of sea level rise, and potentially up to 4 feet of rise by 2100. Additionally, climate change is linked to intensified hurricanes, a hazard for the South Carolina coastline every year. Both of these scenarios result in increases in the regularity and severity of coastal flooding, making the threat of permanent or temporary displacement (relocation) from coastal lands a reality. This is a particularly pressing matter for African American communities already made vulnerable by the long history of racial discrimination in …

Marginally Interpretable Models And Multilevel Models For Quantile Regression With Random-Effects, Nahid Sultana Sumi

Theses and Dissertations

The quantile regression model is an active area of statistical research that has received a lot of attention. This complements the most widely used statistical tool, that is, mean regression analysis. Quantile regression analysis It has become more flexible because of its properties that include no assumption on the distribution of the response variable, equivalent to monotone transformations, and robustness to outliers. However, regression analysis offers methodological challenges if the observations are not independent. Cluster, multilevel, and repeated measures (longitudinal data) designs introduce such dependence. The correlation between observations on the same units or clusters should be accounted for to …

The Classification Of Basket Neural Cells In The Mammalian Neocortex, Sreya Pudi

Senior Theses

Basket neuronal cells of the mammalian neocortex have been classically categorized into two or more groups. Originally, it was thought that the large and small types are the naturally occurring groups that emerge from reasons that relate to neurobiological function and anatomical position. Later, a study based on anatomical and physiological features of these neurons introduced a third type, the net basket cell which is intermediate in size as compared to the large and small types. In this study, multivariate analysis was used to test the hypothesis that the large and small types are morphologically distinct groups. The results of …

Teaching An Old Dog New Tricks: Synthesis And Applications Of Novel Polybenzimidazole (Pbi) Membranes, Laura Ann Murdock

Theses and Dissertations

Polybenzimidazoles (PBIs) represent a class of performance polymers that display exceptional thermal and oxidative stability. For almost thirty years, PBI membranes have been investigated as promising candidates for next-generation alternative energy devices, including high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) and vanadium redox flow batteries (VRBs). Issues with the production of PBI membranes arise from their inherent low solubility in organic solvents. Thus, conventional approaches typically yield membranes that have limited molecular weight and generate significant waste in preparation, due to the large quantity of solvent required to dissolve PBIs for membrane casting.

Presented herein is the development of …

Multi-Objective Routing For Distributed Controllers, Konstantin Y. Rubin

Theses and Dissertations

A long-term goal of future naval shipboard power systems is the ability to manage energy flow with sufficient flexibility to accommodate future platform requirements such as better survivability, continuity, and support of pulsed and other demanding loads. To facilitate scalable, low-latency global distributed system control, each control module can include an integrated network interface connected through multiple channels onto a direct, multi-hop network topology. In this work, we focus on a 2D Torus, in which control nodes are arranged in a regular 2D grid, with each node connected through point-to-point connections to its four immediate neighbors. An important advantage of …

Optimization And Application Of Electrochemical Probes For Neurotransmitter Detection, Colby E. Witt

Theses and Dissertations

The brain is a complex matrix that is difficult to study. Signaling molecules, neurotransmitters, are constantly being released and sequestered back into neurons within milliseconds to facilitate communication and normal function, a process called neurotransmission. There are few analytical techniques available to selectively probe such a dynamic system, and even fewer can detect these discrete changes in real-time. In order to make robust measurements in the brain you need speed, sensitivity, selectivity and small probe size, which are encompassed by fast-voltammetry with microelectrodes. Traditional fast-voltammetry at carbon fiber microelectrodes (fast-scan cyclic voltammetry (FSCV)) requires background subtraction to overcome the large …

Multiple Frailty Model For Spatially Correlated Interval-Censored, Wanfang Zhang

Theses and Dissertations

In this paper, we consider the problem of multiple frailty selection for general interval-censored spatial survival data, which often occurs in clinical trials and epidemiological studies. The general interval-censored data is a mixture of left-, right- and interval-censored data. We propose a Bayesian semiparametric approach based on the Cox proportional hazard model, where monotone splines were used for non-parametrical modeling of the cumulative baseline hazards where the variable selection priors were used for frailty selection. A two-stage data augmentation with Poisson latent variables is developed for efficient computation. The approach is evaluated based a simulation study and illustrated using a …

Towards More Trustworthy Deep Learning: Accurate, Resilient, And Explainable Countermeasures Against Adversarial Examples, Fei Zuo

Theses and Dissertations

Despite the great achievements made by neural networks on tasks such as image classification, they are brittle and vulnerable to adversarial example (AE) attacks, which are crafted by adding human-imperceptible perturbations to inputs in order that a neural-network-based classifier incorrectly labels them. Along with the prevalence of deep learning techniques, the threat of AEs attracts increasingly attentions since it may lead to serious consequences in some vital applications such as disease diagnosis.

To defeat attacks based on AEs, both detection and defensive techniques attract the research community’s attention. Given an input image, the detection system outputs whether it is an …

Enhancing Charge Carrier Mobility In Colloidal Quantum Dots For Technological Applications, Fiaz Ahmed

Theses and Dissertations

Colloidal quantum dots (QD) are promising semiconducting materials to engineer photovoltaic and optoelectronic devices due to tunable size-dependent absorption and emission properties. These materials are important as they don’t need complicated equipment and huge setup investment for industrial applications. If formulated into a kind of stable nano-ink, these QDs can be incorporated into devices using the most economical processing technologies, spray or roll to roll printing. More importantly, these are compatible with thin-film stacked devices and circuitry that can be formed on heat-sensitive and flexible substrates to make flexible wearable devices and sensors that are difficult to achieve with crystalline-based …

Investigating The Chemistry Of Harmful Algal Blooms And Microbial Communities In The Natural Environment, Samuel Patrick Putnam

Theses and Dissertations

Cyanobacteria has existed on the planet for over 3 billion years, and as technology, science, and industry have allowed us to shape our world, these changes have caused a proliferation of biomass. Higher carbon dioxide levels in the atmosphere, warmer temperatures, and rapid increases in the nutrient cycle have created excellent growing conditions for cyanobacteria, making them endemic in fresh waters throughout the world. The work in this dissertation was directed towards the secondary metabolites produced by cyanobacteria and other surrounding microbes and understanding their concentrations and release in natural systems. Analytical methods were developed for the extraction and quantification …

Shedding Light On The Coupling Dynamics In Hybrid Nanostructures, Saba Arash

Theses and Dissertations

Here we present all-optical investigations of two hybrid nanostructures. In the first hybrid system, we study Janus-type nanofibers consisting of two hemi-cylinders of ferroelectric barium titanate and ferrimagnetic cobalt ferrite. Using the magnetic field-dependent polarization-resolved second harmonic generation technique, we observe a strong magnetoelectric coupling between the two ferroic constituents at room temperature. Corroborating these results by X-ray diffraction, we can also extract repeatable memory-dependent behaviors in these biphasic nanofibers. In the second hybrid system, we study the interaction between the semiconductor indium/gallium arsenide quantum dots and surface plasmon supporting silver structures in the weak coupling regime. When quantum dots …

Developing Covalent-Organic Frameworks For Protecting Against Radiation, Megan J. Francis

Senior Theses

This research focuses on the development of lightweight, thermostable dual-function materials for secondary radiation protection and sensing by the integration of hydrogen-rich aliphatic chains inside the porous matrix of covalent-organic frameworks (COFs). The main aims of this project are the synthesis of organic linkers for forming a robust porous COF, synthesizing the porous COF through a condensation reaction, the development of hydrogen-rich aliphatic chains, and integration of aliphatic chains into COFs through click chemistry. This manuscript outlines the methodology and development of a novel self-assembled crystalline, porous material engineered to combine the functions of a shield and sensitive dosimeter. The …

Characterization Of A Novel Fe-S Cluster Transfer Pathway Between Grx4 And Sufa In Escherichia Coli, Enis Sanchez

Theses and Dissertations

Biogenesis of iron-sulfur (Fe-S) clusters is an essential process in living organisms due to the critical role of Fe-S cluster proteins in a myriad of cellular functions. During the assembly of Fe-S clusters, multi-protein complexes are used to drive the mobilization and protection of reactive sulfur and iron intermediates, regulate assembly of various Fe-S clusters on an ATPase-dependent, multi-protein scaffold, and target nascent clusters to their downstream protein targets. In each of the Fe-S cluster biogenesis steps, specific protein-protein interactions (PPIs) are required for proper function of the assembly pathway. The target pathway is the sulfur formation (Suf) pathway for …

Association Between The Beta Band Neural Response And The Behavioral Performance In Aphasic And Neurologically Intact Individuals, Yilun Zhang

Theses and Dissertations

The complex motor act of speech requires integrating linguistic and sensorimotor processes. Sensorimotor interaction mainly supports speech production in the form of state feedback control architecture. While speaking, subjects react to perturbations in the pitch of voice auditory feedback by changing their tone in the opposite direction to pitch-shift stimuli to compensate for the perceived pitch shift. Aphasia is a communication impairment affecting patients’ speaking, understanding, reading, and writing. The present study aims to examine the association between brain neural activity and the ability for speech auditory feedback error correction in both post-stroke aphasia and neurologically intact individuals. There are …

Sampling And Robustness In Multi-Robot Visibility-Based Pursuit-Evasion, Trevor Vincent Olsen

Theses and Dissertations

Given a two-dimensional polygonal space, the multi-robot visibility-based pursuit-evasion problem tasks several pursuer robots with the goal of establishing visibility with an arbitrarily fast evader. The best-known complete algorithm for this problem takes time doubly exponential in the number of robots. However, sampling-based techniques have shown promise in generating feasible solutions in these scenarios.

Existing sampling-based algorithms have long execution times and high failure rates for complex environments. We first address that limitation by proposing a new algorithm that takes an environment as its input and returns a joint motion strategy which ensures that the evader is captured by one …

From Persistent Radicals To Conductivity: A Structure Property Investigation In A Series Of Urea-Tethered Halogenated Triphenylamines, Muhammad Saddam Hossain

Theses and Dissertations

Triphenylamines (TPAs) are known to form persistent organic radicals either by chemical, electrochemical or photoinduced oxidation. Typically, fully para-substituted TPAs form stable radical cations while the radical cations in partially substituted systems quickly degrade. Herein, we study the effects of solid-state organization on a series of urea tethered halogenated TPAs 1 (X = H, Cl, Br, I) and compare their radical cation formation and persistence after UV-irradiation. These halogenated urea tethered TPAs were examined by single-crystal X-ray diffraction where their assembly was guided by threecentered urea hydrogen bonding interaction. As expected, all compounds form photogenerated radical cations in solution, but …

Polymeric Sorbents For Solid-Phase Extraction (Spe) Of Polar Analytes And Carbon Dioxide Capture, Ishwor Karki

Theses and Dissertations

The main topics of this dissertation are: 1) the study of hydrophilic-lipophilic balance (HLB) polymer monoliths for solid-phase extraction (SPE) applications, 2) molecularly imprinted polymers (MIPs) for capturing the CO2 gas and 3) the application of symmetry-adapted perturbation theory (SAPT) calculations to examine the origins of non-covalent interactions.

HLB polymers are popular sorbent materials in separation science. The Divinylbenzene-co-N-vinylpyrrolidone (DVB-co-NVP) polymer is one of the most widely used general-purpose HLB polymers. Despite the popularity of HLB polymer stationary phases, the studies of the adsorption properties of DVB-co-NVP have only been reported over a narrow …

Robot Area Coverage Path Planning In Aquatic Environments, Nare Karapetyan

Theses and Dissertations

This thesis is motivated by real world problems faced in aquatic environments. It addresses the problem of area coverage path planning with robots - the problem of moving an end-effector of a robot over all available space while avoiding existing obstacles. The problem is considered first in a 2D space with a single robot for specific environmental monitoring operations, and then with multi-robot systems — a known NP-complete problem. Next we tackle the coverage problem in 3D space - a step towards underwater mapping of shipwrecks or monitoring of coral reefs.

The first part of this thesis leverages human expertise …

Investigations On The Surface Chemistry Of Colloidal Quantum Dots Towards Fluorescent Biological Probes, John Hardin Dunlap

Theses and Dissertations

Colloidal semiconductor quantum dots (QDs) have garnered significant interest as promising materials for biological applications due to their improved photostability and narrow, tunable photoluminescence properties compared to organic fluorophores. To facilitate their utility as fluorescent bioimaging probes, QDs must undergo post-synthetic modifications to exchange their native hydrophobic ligands from synthesis with hydrophilic ones that enable colloidal dispersions in aqueous environments. Many examples exist that demonstrate surface modifications for water-soluble QDs and their efficacy in biological systems, however, there is a need to develop a more thorough understanding of how hydrophilic ligands coordinate to QD surfaces in order to develop more …

Correcting For Measurement Error In The Outcome When Estimating The Distribution Of Time To Pregnancy With The Current Duration Approach, Nicole Nasrallah

Theses and Dissertations

The current duration approach to modeling time-to-pregnancy (TTP) models the length of pregnancy attempt for women that are currently attempting pregnancy. There is a scarcity of studies, let alone TTP studies, that account for measurement error in the outcome. Previously, the benefits of a piecewise constant model with regards to bias in estimates of the survival function with measurement error and the parametric modelling of TTP was shown. In this thesis, correcting for measurement error in the outcome with the current duration approach is explored through piecewise constant models with log-normal measurement error. Five different methods are compared to determine …

Using Concurrent Functional Regression To Reconstruct River Stage Data During Flood Events And Identify Influential Functional Measurements, Ryan Pittman

Theses and Dissertations

On October 4, 2015, the Cedar Creek gage at Congaree National Park stopped reporting stages, and the readings did not resume until approximately two weeks later because of record-breaking rainfall that led to some of the worst flooding in South Carolina history. Our goal is to reconstruct the Cedar Creek stage during this missing two-week window. The Congaree River gage in Congaree National Park remained functioning throughout the October 2015 flood, when the stage reached its maximum recorded crest. The stages from the two gages are directly related during floods as water travels through the local spillways and flood planes …

Correct Web Service Transactions In The Presence Of Malicious And Misbehaving Transactions, John Thomas Ravan Iii

Theses and Dissertations

Concurrent database transactions within a web service environment can cause a variety of problems without the proper concurrency control mechanisms in place. A few of these problems involve data integrity issues, deadlock, and efficiency issues. Even with today’s industry standard solutions to these problems, they have taken a reactive approach rather than proactively preventing these problems from happening. We deliver a solution, based on prediction-based scheduling to ensure consistency while keeping execution time the same or faster than current industry solutions. The first part of this solution involves prototyping and formally proving a prediction-based scheduler.

The prediction-based scheduler leverages a …

Exploration Of Vase As An Extraction Method For Emerging Disinfection By-Products And Acidic Methanol As A Safe And Effective Derivatization Method For Haloacids, Madison Leigh Kilpatrick

Theses and Dissertations

This project aims to create an environmentally friendly, robust, and efficient extraction and preconcentration method in both the detection and quantification of various disinfection by-products (DBPs). Vacuum assisted sorbent extraction (VASE) is a newly developed method in the extraction of both volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs). This extraction method is paired with a Thermo Scientific TSQ Quantum Triple Quadrupole GC-MS system for the quantification of DBPs. VASE outperforms current DBP extraction methods, with liquid-liquid extraction (LLE) being the most used alternative, because of its minimal use of solvent, high level of automation, and over-all ease of …

Simulation Of Pituitary Organogenesis In Two Dimensions, Chace E. Covington

Theses and Dissertations

The pituitary gland is a vital part of the endocrine system found in all vertebrates and is responsible for the production of hormones that influence many physiological processes in the organism’s body. Although much has been learned of pituitary organogenesis, studying the dynamics of the cells in the developing pituitary gland is difficult. Pituitary organogenesis has been studied through “snapshots” of a developing pituitary gland by removing and viewing the pituitary glands of different specimens. Thus, how the individual cells in the developing pituitary gland behave and interact with one another is not fully understood. To aid in understanding pituitary …

Regression Methods For Group Testing Data, Michael Stutz

Theses and Dissertations

Group testing is an efficient method of disease screening, whereby individual specimens (e.g., blood, urine, etc.) are pooled together and tested as a whole for the presence of disease. A common goal is to use data arising from these testing protocols to better understand the relationship between disease status and potential risk factors (e.g., age, symptom status, etc.). Numerous statistical methodologies have been developed for this purpose, most of which are built within the framework of a generalized linear model. Recent authors have suggested the inadequacy of such regression methods to capture the true functional relationships when nonlinear effects are …

Ahr Expression On Rorc-Expressing Immune Cells Is Essential For I3c-Mediated Protection Against Colitis, Michal C. Williams

Senior Theses

Colitis is an inflammatory bowel disorder (IBD) whose etiology is attributed to modification in the luminal microbiota and dysregulation in the immune response. Indole is a signaling molecule which is naturally produced by gut luminal microbiota. Indole-3- carbinol (I3C) is a compound commonly found in vegetables and a ligand for the aryl hydrocarbon receptor (AhR). Previous studies have detected decreased expression and activation on the AhR receptor in colitis patients, thought to possibly alter gut microbiota metabolism, subsequently promoting colitis. 1 AhR, expressed in a variety of immune and epithelial cells, contributes to gut homeostasis by affecting vital mediators such …

Trimming Complexes, Keller Vandebogert

Theses and Dissertations

We produce a family of complexes called trimming complexes and explore applications. We first study ideals defining type 2 compressed rings with socle minimally generated in degrees s and 2s − 1 for s > 2. We prove that all such ideals arise as trimmings of grade 3 Gorenstein ideals and show that trimming complexes yield an explicit free resolution. In particular, we give bounds on parameters arising in the Tor-algebra classification and construct explicit ideals attaining all intermediate values for every s. This partially answers a question of realizability of Tor-algebra structures posed by Avramov. Next, we study how …

Groundwater Discharge From Passive Continental Margins: Rethinking Marine Chemical Budgets, Andrew William Osborne

Theses and Dissertations

Geothermal convection and sediment compaction drive large-scale flow in continental shelves. We suggest that this flow is an overlooked control on the major ion chemistry of the ocean. Conventional ocean chemical budgets are constructed using river discharge, axial mid-ocean ridge (MOR) convection and CaCO3 production, but these budgets are still poorly quantified. We synthesized data from 17 passive continental margin basins to calculate a range of estimated groundwater and chemical fluxes from continental shelves, considering five major ions (Ca2+, Na+, K+, Mg2+, and Cl-). When extrapolated globally, volumetric groundwater flux estimates were comparable to those for MOR axial circulation, and …

Plasmonic Metallic And Semiconductor Nanomaterials, Mengqi Sun

Theses and Dissertations

The earliest account of localized surface plasmon resonance (LSPR) has to date back to the ancient age of Rome in 400 A.D. The famous glass of Lycurgus cup told the story of unique light-and-matter interaction at the nanoscale that confines the electromagnetic field resonance at its surface and therefore allows LSPR feature to noticeably arise. The conventional metallic LSPR nanomaterials, like Au and Ag nanoparticles attract constant attentions due to their synthetic simplicity, chemical robustness, and visible spectral response. Its ability to generate sensitive dielectric sensing of the surroundings, strong electromagnetic field and active charge carriers upon optical excitation triggered …