Physical Sciences and Mathematics Commons^™

A Remark On The Multipliers On Spaces Of Weak Products Of Functions, Stefan Richter, Brett D. Wick

Mathematics Faculty Research

Operators on function spaces of form Cɸf = f ∘ ɸ, where ɸ is a fixed map are called composition operators with symbol ɸ. We study such operators acting on the Hilbert Hardy space over the right half-plane and characterize the situations when they are invertible, Fredholm, unitary, and Hermitian. We determine the normal composition operators with inner, respectively with Möbius symbol. In select cases, we calculate their spectra, essential spectra, and numerical ranges.

Light-Activated Photocurrent Degradation And Self-Healing In Perovskite Solar Cells, Wanyi Nie, Jean-Christophe Blancon, Amanda J. Neukirch, Kannatassen Appavoo, Hsinhan Tsai, Manish Chhowalla, Muhammad A. Alam, Matthew Y. Sfeir, Claudine Katan, Jacky Even, Sergei Tretiak, Jared J. Crochet, Gautam Gupta, Aditya D. Mohite

Publications and Research

Solution-processed organometallic perovskite solar cells have emerged as one of the most promising thin-film photovoltaic technology. However, a key challenge is their lack of stability over prolonged solar irradiation. Few studies have investigated the effect of light soaking on hybrid perovskites and have attributed the degradation in the optoelectronic properties to photochemical or field-assisted ion migration. Here we show that the slow photocurrent degradation in thin-film photovoltaic devices is due to the formation of light-activated meta-stable deep-level trap states. However, the devices can self-heal completely by resting them in the dark for <1 min or the degradation can be completely prevented by operating the devices at 0°C. We investigate several physical mechanisms to explain the microscopic origin for the formation of these trap states, among which the creation of small polaronic states involving localized cooperative lattice strain and molecular orientations emerges as a credible microscopic mechanism requiring further detailed studies.

Gaiseing Into The New Guidelines, Robert Carver, Megan Mocko, Jeffrey Witmer, Beverly Wood

Publications

The first GAISE College Report came out in 2005. Over the past ten years our discipline has changed in many ways, including but not limited to what type of data is easily available, the technology that we use, as well as how we teach students. In this presentation we will briefly start with how the new GAISE 2016 guidelines and goals have changed, including the two new emphases of statistical thinking: giving students experience with multivariable thinking and with the investigative process. So how do you start to implement these new ideas? In this presentation, we will demonstrate an activity …

Transportation Asset Exposure, Adaptation Alternatives, And Infrastructure Resilience: Steering Committee Project Appraisal, Bahar Barami

May 18, 2016: The Economic Impacts of Sea-Level Rise in Hampton Roads

PDF of powerpoint presentation at the workshop "The Economic Impacts of Sea-Level Rise in Hampton Roads: An Appraisal of the Projects Underway" on May 18, 2016 at the Virginia Modeling and Simulation Center, 1030 University Blvd, Suffolk, VA 23435

Gamma Aapeptides As Host Defense Peptide Mimics, Yaqiong Li

USF Tampa Graduate Theses and Dissertations

There has been increasing concern regarding the emergence of multi-drug resistant pathogens. The resistance develops when pathogens, especially bacteria, are frequently exposed to conventional antibiotics, as they are heavily used in both human and livestock. This is due to the high target specificity of conventional antibiotics, which places pathogens in high selective pressures and eventually results in drug resistant by mutations. To address this issue, global actions and cooperation are needed. At the same time, new technologies and strategies need to be developed. Host defense peptides (HDPs) are widely found in the innate immune system. They show both direct antimicrobial …

Cone In Cone Concretions Of The Stanley Group In Southeastern Oklahoma, Kyle B. Ayres

Electronic Theses and Dissertations

Cone in cone concretions found in the Stanley Group of Southeastern Oklahoma have a variety of external and internal attributes which allow diagenetic and theoretical models of formation to be hypothesized. Stanley Group carbonate cone in cone concretions are initially formed in sulfur reducing horizons at shallow burial depths in a poorly circulated possibly deep trough containing siliceous sediments and organic matter. Collected concretions near the town of Smithville, Oklahoma displayed four different external morphologies and four variations of mineral constituents. All concretions contained microscopic cones which initiated diffusion and/or fluid patterns and is an early cementation process that directly …

Inhibitory Effects Of Unique Sulfonamides On Leishmania Tarentolae And Potential Pathway Of Inhibition, Jade M. Katinas

Theses and Dissertations

Leishmaniasis is an endemic disease caused by the protozoan parasite Leishmania. Current treatments for the parasite are limited by cost, availability, and drug resistance as the worldwide occurrence of leishmaniasis continues to be more prevalent. Sulfonamides are a class of compounds with medicinal properties that have been used to treat bacterial and parasitic diseases via various pathways. In this study, newly synthesized, unique structural analogs of sulfonamide compounds were assessed for their impact on Leishmania cell viability and potential pathways for inhibition were evaluated. Leishmania tarentolae (ATCC Strain 30143) axenic promastigote cells were grown in BHI medium and treated with …

The Power Of X, Darren B. Glass

Math Faculty Publications

In his recent book, The Math Myth: And Other STEM Delusions, political scientist Andrew Hacker argues, among other things, that we should not require high school students to take algebra.

Part of his argument, based on data some have questioned, is that algebra courses are a major contributor to students dropping out of high school. He also argues that algebra is nothing more than an "enigmatic orbit of abstractions" that most people will never use in their jobs. [excerpt]

Was 2015 The Summer Of The Shark? Evidence From The Coastal Carolina University Shark Project, Brooke Anderson

Honors Theses

Winyah Bay is a 65-km2 estuary in northeast South Carolina and is considered essential habitat and nursery ground for several shark species of the western North Atlantic. As a result of a number of shark bites/attacks during the summer of 2015, many concluded there was higher abundance of sharks than in previous years. The objective of this study was to test this hypothesis using surveys of shark populations from Winyah Bay in the summer of 2015, and comparing the diversity and abundance of sharks from this survey to those of previous years from the same survey. From July to August …

Abundance And Distribution Of Microplastic Particles In Winyah Bay, S.C. ‌, Dillon King

Honors Theses

Plastics are incredibly durable synthetic polymers used in a wide variety of consumer products. Microplastics are generally defined as plastic debris ranging from 0.33 to 5 millimeters in size. Microplastic pollution in the environment is a global concern because of their propensity to serve as a vector for bioaccumlation and the spread of harmful bacteria. This study characterized the concentrations of floating microplastics in Winyah Bay, South Carolina, the surrounding freshwater river systems, and 10 miles offshore of Winyah Bay. Samples were collected according to NOAA standard techniques for microplastic collection in water using a 335 µm and 153 µm …

Development Of A [2]-Catenane Synthetic Method And A Student Beliefs Survey For A Hybrid Organometallics Course, Jourdan E. Lakes

Honors Theses

In this study, the value-added of a new upper-level chemistry course, CHEM 372-Organometallics, was defined using a Student Beliefs Survey that was answered by students in CHEM 372 and by faculty who teach upper-level chemistry courses at Coastal Carolina University. The laboratory portion of CHEM 372 focused on the synthesis of a [2]-catenane, which is a molecularly interlocked molecule (MIM). The intention was to give the CHEM 372 students a goal to work toward over the course of the semester instead of different, unrelated, experiments each week. Using this style of lab teaching, the students were introduced to graduate school-level …

Seismic Studies Of The Tonga Subduction Zone And The Lau Back-Arc Basin, Songqiao Wei

Arts & Sciences Graduate Student Theses and Dissertations

This dissertation utilizes multiple techniques of seismic tomography and earthquake location to investigate the upper mantle structure and intermediate-depth seismicity of the Tonga subduction zone, the Lau back-arc basin, and adjacent regions. Data for these studies consist of broadband records from 49 ocean bottom seismographs and 17 island-based seismic stations deployed for one year in 2009-2010, as well as more limited earlier datasets. I conducted tomographic studies of Rayleigh wave velocity and body wave attenuation to examine the thermal variations and the distribution of partial melt in the mantle wedge. The shear-wave velocity structure is first determined using only teleseismic …

No-Slip Billiards, Christopher Lee Cox

Arts & Sciences Graduate Student Theses and Dissertations

We investigate the dynamics of no-slip billiards, a model in which small rotating disks may exchange linear and angular momentum at collisions with the boundary. A general theory of rigid body collisions in is developed, which returns the known dimension two model as a special case but generalizes to higher dimensions. We give new results on periodicity and boundedness of orbits which suggest that a class of billiards (including all polygons) is not ergodic. Computer generated phase portraits demonstrate non-ergodic features, suggesting chaotic no-slip billiards cannot easily be constructed using the common techniques for generating chaos in standard billiards. However, …

Examining Cost Functionality And Optimization: A Case Study On Testing The Reasonableness Of New Aircraft Using Historical Aircraft Data, Katherine Jozefiak

Arts & Sciences Graduate Student Theses and Dissertations

When pursuing business by competing for government contracts, proving the submitted price is reasonable is often required. This proof is called a test of reasonableness. This study analyzes data from historical aircraft programs in relation of a new aircraft program in order to demonstrate the estimated cost of the new program is reasonable. The purpose of this study is to investigate three questions. Is the new program cost reasonable using current industry and government parameters? Is it better to look at programs from a total cost perspective or break the total cost into subcategory levels? Finally, this study applies a …

Spot Volatility Estimation Of Ito Semimartingales Using Delta Sequences, Weixuan Gao

Arts & Sciences Graduate Student Theses and Dissertations

This thesis studies a unifying class of nonparametric spot volatility estimators proposed by Mancini et. al.(2013). This method is based on delta sequences and is conceived to include many of the existing estimators in the field as special cases. The thesis first surveys the asymptotic theory of the proposed estimators under an infill asymptotic scheme and fixed time horizon, when the state variable follows a Brownian semimartingale. Then, some extensions to include jumps and financial microstructure noise in the observed price process are also presented. The main goal of the thesis is to assess the suitability of the proposed methods …

Revelation Of Yin-Yang Balance In Microbial Cell Factories By Data Mining, Flux Modeling, And Metabolic Engineering, Gang Wu

McKelvey School of Engineering Graduate Student Theses & Dissertations

The long-held assumption of never-ending rapid growth in biotechnology and especially in synthetic biology has been recently questioned, due to lack of substantial return of investment. One of the main reasons for failures in synthetic biology and metabolic engineering is the metabolic burdens that result in resource losses. Metabolic burden is defined as the portion of a host cells resources either energy molecules (e.g., NADH, NADPH and ATP) or carbon building blocks (e.g., amino acids) that is used to maintain the engineered components (e.g., pathways). As a result, the effectiveness of synthetic biology tools heavily dependents on cell capability to …

Theory Of Carrier Transport From First Principles: Applications In Photovoltaic And Thermoelectric Materials, Alireza Faghaninia

McKelvey School of Engineering Graduate Student Theses & Dissertations

New sources of energy that are environmentally friendly, cost-effective, and renewable are essential if we are to combat the effects of global climate change. Two of these sources are solar photovoltaic (PV) cells to convert sunlight into electricity and thermoelectric (TE) devices to convert heat to electricity. To be practical on a large scale, the properties (e.g. electrical conductivity, band gap, Seebeck coefficient, etc) of the the underlying materials must be improved significantly through judicious control of structure and composition. Significant understanding of materials properties is required to design and engineer new high-performing materials. First principles calculations using density functional …

Goggle Augmented Imaging And Navigation System For Fluorescence-Guided Surgery, Suman Bikash Mondal

McKelvey School of Engineering Graduate Student Theses & Dissertations

Surgery remains the only curative option for most solid tumors. The standard-of-care usually involves tumor resection and sentinel lymph node biopsy for cancer staging. Surgeons rely on their vision and touch to distinguish healthy from cancer tissue during surgery, often leading to incomplete tumor resection that necessitates repeat surgery. Sentinel lymph node biopsy by conventional radioactive tracking exposes patients and caregivers to ionizing radiation, while blue dye tracking stains the tissue highlighting only superficial lymph nodes. Improper identification of sentinel lymph nodes may misdiagnose the stage of the cancer. Therefore there is a clinical need for accurate intraoperative tumor and …

Cyclotron Production And Biomedical Imaging Applications Of The Pet Isotope Manganese-52, Andrew Lake Wooten

McKelvey School of Engineering Graduate Student Theses & Dissertations

Manganese is an important element for biomedical research because of its roles as an essential micronutrient and as a neurotoxin from chronic elevated exposure, as well as the role of manganese(II) as a paramagnetic core for contrast agents in T1-weighted magnetic resonance imaging (MRI). Using a radiotracer of manganese provides excellent sensitivity for studying these phenomena, but only 52Mn met the criteria for our experiments: (1) a half-life (t1/2=5.6 days) that was long enough to examine timepoints over several days, (2) a half-life that was short enough to emit sufficient counts for a realistic scan time, and (3) emitted radiation …

A General Framework Of Large-Scale Convex Optimization Using Jensen Surrogates And Acceleration Techniques, Soysal Degirmenci

McKelvey School of Engineering Graduate Student Theses & Dissertations

In a world where data rates are growing faster than computing power, algorithmic acceleration based on developments in mathematical optimization plays a crucial role in narrowing the gap between the two. As the scale of optimization problems in many fields is getting larger, we need faster optimization methods that not only work well in theory, but also work well in practice by exploiting underlying state-of-the-art computing technology.

In this document, we introduce a unified framework of large-scale convex optimization using Jensen surrogates, an iterative optimization method that has been used in different fields since the 1970s. After this general treatment, …

Automatically Characterizing Product And Process Incentives In Collective Intelligence, Allen Brockhurst Lavoie

McKelvey School of Engineering Graduate Student Theses & Dissertations

Social media facilitate interaction and information dissemination among an unprecedented number of participants. Why do users contribute, and why do they contribute to a specific venue? Does the information they receive cover all relevant points of view, or is it biased? The substantial and increasing importance of online communication makes these questions more pressing, but also puts answers within reach of automated methods. I investigate scalable algorithms for understanding two classes of incentives which arise in collective intelligence processes. Product incentives exist when contributors have a stake in the information delivered to other users. I investigate product-relevant user behavior changes, …

Distributed Target Tracking And Synchronization In Wireless Sensor Networks, Jichuan Li

McKelvey School of Engineering Graduate Student Theses & Dissertations

Wireless sensor networks provide useful information for various applications but pose challenges in scalable information processing and network maintenance. This dissertation focuses on statistical methods for distributed information fusion and sensor synchronization for target tracking in wireless sensor networks.

We perform target tracking using particle filtering. For scalability, we extend centralized particle filtering to distributed particle filtering via distributed fusion of local estimates provided by individual sensors. We derive a distributed fusion rule from Bayes' theorem and implement it via average consensus. We approximate each local estimate as a Gaussian mixture and develop a sampling-based approach to the nonlinear fusion …

Learning With Scalability And Compactness, Wenlin Chen

McKelvey School of Engineering Graduate Student Theses & Dissertations

Artificial Intelligence has been thriving for decades since its birth. Traditional AI features heuristic search and planning, providing good strategy for tasks that are inherently search-based problems, such as games and GPS searching. In the meantime, machine learning, arguably the hottest subfield of AI, embraces data-driven methodology with great success in a wide range of applications such as computer vision and speech recognition. As a new trend, the applications of both learning and search have shifted toward mobile and embedded devices which entails not only scalability but also compactness of the models. Under this general paradigm, we propose a series …

Exploiting The Weak Generational Hypothesis For Write Reduction And Object Recycling, Jonathan Andrew Shidal

McKelvey School of Engineering Graduate Student Theses & Dissertations

Programming languages with automatic memory management are continuing to grow in popularity due to ease of programming. However, these languages tend to allocate objects excessively, leading to inefficient use of memory and large garbage collection and allocation overheads.

The weak generational hypothesis notes that objects tend to die young in languages with automatic dynamic memory management. Much work has been done to optimize allocation and garbage collection algorithms based on this observation. Previous work has largely focused on developing efficient software algorithms for allocation and collection. However, much less work has studied architectural solutions. In this work, we propose and …

Classification Trees And Rule-Based Modeling Using The C5.0 Algorithm For Self-Image Across Sex And Race In St. Louis, Rohan Shirali

Arts & Sciences Graduate Student Theses and Dissertations

The study population comprised children, adolescents, and adults who were residents of the city of St. Louis at the time of data collection in 2015. The data collected includes sex, age, race, measured height and weight, self-reported height and weight, zip code, educational background, exercise and diet habits, and descriptions and strategies of participants' weight (i.e. overweight and trying to lose weight, respectively). I use the C5.0 algorithm to create classification trees and rule-based models to analyze this population. Specifically, I model a binary self-image variable as a function of sex, age, race, zip code, and a ratio of reported …

Visualization Of Deep Convolutional Neural Networks, Dingwen Li

McKelvey School of Engineering Graduate Student Theses & Dissertations

Deep learning has achieved great accuracy in large scale image classification and scene recognition tasks, especially after the Convolutional Neural Network (CNN) model was introduced. Although a CNN often demonstrates very good classification results, it is usually unclear how or why a classification result is achieved. The objective of this thesis is to explore several existing visualization approaches which offer intuitive visual results. The thesis focuses on three visualization approaches: (1) image masking which highlights the region of image with high influence on the classification, (2) Taylor decomposition back-propagation which generates a per pixel heat map that describes each pixel's …

Environmental Fullerene Chemistry: Elucidating Critical Reaction Pathways And Resulting Products In The Aqueous Phase, Jiewei Wu

McKelvey School of Engineering Graduate Student Theses & Dissertations

As the production of fullerenes and fullerene-based materials approaches industrial scale, there are increasing interests/concerns regarding their (potential) environmental impact(s) upon release. To date, a number of critical, aqueous-based fullerene transformation pathways under environmentally relevant conditions remain poorly understood. Comprehensive, fundamental, and quantitative understanding of the potential (major) reaction pathways and resulting products of fullerene materials, particularly in aquatic systems, is now crucial for their accurate fate, transport, life cycle, risk assessment(s), and thus ultimate material sustainability.

Herein, this dissertation is focused on identifying and elucidating aqueous transformation pathways of fullerene materials, focused on C60 as a model fullerene, under …

Modeling, Simulation, And Analysis Of Lithium-Ion Batteries For Grid-Scale Applications, Matthew Thomas Lawder

McKelvey School of Engineering Graduate Student Theses & Dissertations

Lithium-ion batteries have become universally present in daily life, being used across a wide range of portable consumer electronics. These batteries are advantageous compared to other forms of energy storage due to their high energy density and long cycle life. These characteristics make lithium-ion batteries advantageous for many new and developing applications that require large scale energy storage such as electric vehicles and the utility grid. Typical uses for lithium-ion batteries require consistent cycling patterns that are predictable and easy to approximate across all uses, but new large scale applications will have much more dynamic demands. The cycling patterns for …

Three Problems In Operator Theory And Complex Analysis, Cheng Chu

Arts & Sciences Graduate Student Theses and Dissertations

This thesis concerns three distinct problems in operator theory and complex analysis. In Chapter 2, we study the following problem: On the Hardy space H^2, when is the product of a Hankel operator and a Toeplitz operator compact? We give necessary and sucient conditions for when such a product H_fT_g is compact. In Chapter 3, we discuss hyponormal Toeplitz operators. We show that for those operators, there exists a lower bound for the area of the spectrum. This extends the known estimate for the spectral area of Toeplitz operators with an analytic symbol. This part is joint work with Dmitry …

Lead Poisoning In United States Children, Zeren Zhou

Arts & Sciences Graduate Student Theses and Dissertations

We investigate factors related to blood lead levels of children ages 1 to 5 in the United States for the years 2007-2014. We use data from the National Health and Nutrition Examination Survey (NHANES). The goal is to explore predictors of lead in childrens' blood and to develop a multivariate model using as many predictors as possible. The analysis is conducted using SAS survey regression procedures that account for weighting, stratification, and clustering of the data.