Physical Sciences and Mathematics Commons^™

Coherent Response Of Two Dimensional Electron Gas Probed By Two Dimensional Fourier Transform Spectroscopy, Jagannath Paul

USF Tampa Graduate Theses and Dissertations

Advent of ultrashort lasers made it possible to probe various scattering phenomena in materials that occur in a time scale on the order of few femtoseconds to several tens of picoseconds. Nonlinear optical spectroscopy techniques, such as pump-probe, transient four wave mixing (TFWM), etc., are very common to study the carrier dynamics in various material systems. In time domain, the transient FWM uses several ultrashort pulses separated by time delays to obtain the information of dephasing and population relaxation times, which are very important parameters that govern the carrier dynamics of materials. A recently developed multidimensional nonlinear optical spectroscopy is …

Germania- And Silica-Based Perfluorinated And Non-Fluorinated Sol-Gel Sorbents For Capillary Microextraction In Chromatographic Analysis, Emre Seyyal

USF Tampa Graduate Theses and Dissertations

Sample preparation is the most time-consuming and error-prone step in chemical analysis. Miniaturization and automation of the sample preparation equipment eliminating or reducing the use of hazardous organic solvents, online hyphenation of sample preparation with analytical instruments in a cost-effective way are important factors that need to be considered to design and implement innovative sample preparation techniques and strategies. Solid-phase microextraction (SPME) is a simple, environmentally benign technique well suited for hyphenation with analytical instruments. However, poor coating stability is a significant drawback of SPME employing conventionally prepared coatings. This shortcoming arises from the lack of chemical bonding between the …

Interference Of Light In Multilayer Metasurfaces: Perfect Absorber And Antireflection Coating, Khagendra Prasad Bhattarai

USF Tampa Graduate Theses and Dissertations

We have studied several metamaterials structures with multiple layers by explaining them theoretically and verifying experimentally. The engineered structures we have designed work either as a perfect absorber or antireflection coating. The multilayer model as we call it Three Layer Model (TLM) has been developed, which gives the total reflection and transmission as a function of reflection and transmission of individual layers. By manipulating the amplitude and phase of the reflection and the transmission of the individual layers, we can get the required functionality of the optoelectronic devices. To get zero reflection in the both perfect absorber and the antireflection …

On The Conformational Dynamics Of Dna: A Perspective From Molecular Dynamics Simulations, Ning Ma

USF Tampa Graduate Theses and Dissertations

The main focus of my dissertation is on the conformational motion of DNA, studied by applying tools from the computational chemistry field. In addition, studies of relative α- and 310 helical stabilities in peptides/mini-proteins, and a molecular flooding study of the retinoid X-receptor as part of a continuing drug design effort are presented. In molecular biology, it has been well known that sequence determines structure, and structure controls function. For proteins or DNA to work properly, the correct configuration is required. Mutations may alter the structure, which can cause malfunction. Non-mutational effects, such as a change in environment may also …

Dynamics Of Multicultural Social Networks, Kristina B. Hilton

USF Tampa Graduate Theses and Dissertations

Historically human endeavors around the globe are in search of bilateral relationships. Knowledge and commerce has played a very significant role in increasing the ability for humans to connect for the betterment of the human species. As the means of communication improve, mutual benefits to the community as a whole also increase. Moreover, the benefits are filtered down to members of the overall community. Recent advancement in electronic communication technologies and in knowledge, in particular, physical, chemical, engineering and medical sciences and philosophies, have facilitated nearly instantaneous multi-cultural interactions. Local problems and solutions have become global. This has generated a …

Mitigation Of Insider Attacks For Data Security In Distributed Computing Environments, Santosh Aditham

USF Tampa Graduate Theses and Dissertations

In big data systems, the infrastructure is such that large amounts of data are hosted away from the users. Information security is a major challenge in such systems. From the customer’s perspective, one of the big risks in adopting big data systems is in trusting the service provider who designs and owns the infrastructure, with data security and privacy. However, big data frameworks typically focus on performance and the opportunity for including enhanced security measures is limited. In this dissertation, the problem of mitigating insider attacks is extensively investigated and several static and dynamic run-time techniques are developed. The proposed …

Optimization And Performance Study Of Select Heating Ventilation And Air Conditioning Technologies For Commercial Buildings, Rajeev Kamal

USF Tampa Graduate Theses and Dissertations

Buildings contribute a significant part to the electricity demand profile and peak demand for the electrical utilities. The addition of renewable energy generation adds additional variability and uncertainty to the power system. Demand side management in the buildings can help improve the demand profile for the utilities by shifting some of the demand from peak to off-peak times.

Heating, ventilation and air-conditioning contribute around 45% to the overall demand of a building. This research studies two strategies for reducing the peak as well as shifting some demand from peak to off-peak periods in commercial buildings:

1. Use of gas heat …

Modeling In Finance And Insurance With Levy-It'o Driven Dynamic Processes Under Semi Markov-Type Switching Regimes And Time Domains, Patrick Armand Assonken Tonfack

USF Tampa Graduate Theses and Dissertations

Mathematical and statistical modeling have been at the forefront of many significant advances in many disciplines in both the academic and industry sectors. From behavioral sciences to hard core quantum mechanics in physics, mathematical modeling has made a compelling argument for its usefulness and its necessity in advancing the current state of knowledge in the 21rst century. In Finance and Insurance in particular, stochastic modeling has proven to be an effective approach in accomplishing a vast array of tasks: risk management, leveraging of investments, prediction, hedging, pricing, insurance, and so on. However, the magnitude of the damage incurred in recent …

Quantity Trumps Quality: Bayesian Statistical Accumulation Modeling Guides Radiocarbon Measurements To Construct A Chronology In Real-Time, Devon Robert Firesinger

USF Tampa Graduate Theses and Dissertations

The development of an accurate and precise geochronology is imperative to understanding archives containing information about Earth’s past. Unable to date all intervals of an archive, researchers use methods of interpolation to approximate age between dates. Sections of the radiocarbon calibration curve can induce larger chronological uncertainty independent of instrumental precision, meaning even a precise date may carry inflated error in its calibration to a calendar age. Methods of interpolation range from step-wise linear regression to, most recently, Bayesian statistical models. These employ prior knowledge of accumulation rate to provide a more informed interpolation between neighboring dates. This study uses …

Scalable Unsupervised Learning With Game Theory, Alireza Chakeri

USF Tampa Graduate Theses and Dissertations

Recently dominant sets, a generalization of the notion of the maximal clique to edge-weighted graphs, have proven to be an effective tool for unsupervised learning and have found applications in different domains. Although, they were initially established using optimization and graph theory concepts, recent work has shown fascinating connections with evolutionary game theory, that leads to the clustering game framework. However, considering size of today's data sets, existing methods need to be modified in order to handle massive data. Hence, in this research work, first we address the limitations of the clustering game framework for large data sets theoretically. We …

Sustainable Development Through Urban Agriculture, Eric R. R. Weaver

USF Tampa Graduate Theses and Dissertations

This document includes three completed publications to represent Urban Agriculture as a ideal solution to meet the UN Sustainable Development Goals. The first publication (Weaver, 2017a) provided in Chapter Two examines the stormwater Best Management Practices (BMP) modelling parameters for the current EPA Stormwater Management Model (SWMM) as the first step to developing Urban Agriculture BMPs. The second publication (Weaver, 2015) provided in Chapter Three highlights how many high-rated scholars have identified agriculture as a critical driver for the planetary systems impacts we find with community development. The third publication (Weaver, 2017b) provided in Chapter Four breaks down a completely …

Tradeoffs In Protocol Designs For Collaborative Authentication, Jacob Venne

USF Tampa Graduate Theses and Dissertations

Authentication is a crucial tool used in access control mechanisms to verify a user’s identity. Collaborative Authentication (co-authentication) is a newly proposed authentication scheme designed to improve on traditional token authentication. Co-authentication works by using multiple user devices as tokens to collaborate in a challenge and authenticate a user request on single device.

This thesis adds two contributions to the co-authentication project. First, a detailed survey of applications that are suitable for adopting co-authentication is presented. Second, an analysis of tradeoffs between varying protocol designs of co-authentication is performed to determine whether, and how, any designs are superior to other …

Using Remote Sensing To Evaluate Wetland Recovery In The Northern Tampa Bay Area Following Reduction In Groundwater Withdrawals, Amor Elder

USF Tampa Graduate Theses and Dissertations

In the past, the Northern Tampa Bay Area (NTBA) wetlands saw severe declines in hydrologic conditions due to excessive groundwater withdrawal rates. Eventually these rates were reduced to allow the wetlands to recover. To monitor this recovery, the Southwest Florida Water Management district (SWFWMD) set up a fieldwork based scoring methodology, called the Wetlands Assessment Procedure (WAP). WAP has been used in many studies of the area since groundwater withdrawal reductions; with many of those studies finding the recovery to be mixed at best. However, these studies were very limited in the number of wetlands they could assess due to …

Abundance And Habitat Preferences Of Introduced Muscovy Ducks (Cairina Moschata), Jacqueline Marie Perry Cahanin

USF Tampa Graduate Theses and Dissertations

Muscovy ducks are native only to Central and South America, Mexico, and parts of southern Texas and are considered invasive in some areas outside of their native range. Although they have been introduced worldwide, they remain largely unstudied. The primary focus of this study was to relate Muscovy duck abundance to habitat characteristics of wetlands in Tampa, Florida. Muscovy abundance was measured using point count methods at 21 wetland sites that occur within an eight km radius of the University of South Florida’s main campus. Habitat features at these sites were assessed using field methods and Geographic Information Systems (GIS) …

3d Cave And Ice Block Morphology From Integrated Geophysical Methods: A Case Study At Scărişoara Ice Cave, Romania, Jackson Durain Hubbard

USF Tampa Graduate Theses and Dissertations

Scărişoara Ice Cave has been a catalyst of scientific intrigue and effort for over 150 years. These efforts have revealed and described countless natural phenomena – and in the process have made it one of the most studied caves in the world.

Of especial interest is the massive ice block located within its Great Hall and scientific reservations. The ice block, which is the oldest and largest known to exist in a cave, has been the focus of multiple surveying and mapping efforts, typically ones utilizing traditional equipment. In this study, the goals were to reconstruct the ice block/cave floor …

Linear Extremal Problems In The Hardy Space HP For 0 < P < 1, Robert Christopher Connelly

USF Tampa Graduate Theses and Dissertations

In this thesis, we consider linear extremal problems in the H^p spaces. For many of these extremal problems, a unique solution can be guaranteed. We will examine some of the classical examples of extremal problems in these spaces. With this framework in place we will then consider a particular problem which does not always have a unique solution.

Schreier Graphs Of Thompson's Group T, Allen Pennington

USF Tampa Graduate Theses and Dissertations

Thompson’s groups F, T, and V represent crucial examples of groups in geometric group theory that bridge it with other areas of mathematics such as logic, computer science, analysis, and geometry. One of the ways to study these groups is by understanding the geometric meaning of their actions. In this thesis we deal with Thompson’s group T that acts naturally on the unit circle S¹, that is identified with the segment [0, 1] with the end points glued together. The main result of this work is the explicit construction of the Schreier graph of T with …

Characterizing The Evolution Of Slab Inputs In The Earliest Stages Of Subduction: Preliminary Evidence From The Fluid-Mobile Element (B, Cs, As, Li) Systematics Of Izu-Bonin Boninitic Glasses Recovered During Iodp Expedition 352, Keir Aavon Sanatan

USF Tampa Graduate Theses and Dissertations

Fluid-mobile elements (FMEs) such as B, Cs, As, Li and Tl can mobilize readily under low P-T conditions (0.2-0.5 GPa). This makes them effective geochemical tracers that can be used as a way of tracking fluid-rock exchanges at the shallow depths encountered in the earliest stages of subduction.

The Izu-Bonin-Mariana (IBM) subduction system is unique in that it preserves a record of the sequences produced from the onset of subduction through the development of arc magmatism. International Ocean Discovery Program (IODP) Expedition 352 recovered >800m of boninite core material from the earliest IBM magmatic events.

Select boninitic glasses from these …

Latitudinal Position And Trends Of The Intertropical Convergence Zone (Itcz) And Its Relationship With Upwelling In The Southern Caribbean Sea And Global Climate Indices, Kaitlyn E. Colna

USF Tampa Graduate Theses and Dissertations

The Intertropical Convergence Zone (ITCZ) is a feature that results from the ocean-atmosphere interactions in the tropics around the world. The ITCZ is characterized by surface wind convergence, tall storm clouds, and it forms a belt of high time-averaged precipitation around the globe. The ITCZ undergoes seasonal migrations between 5°S and 15°N roughly following the subsolar point on Earth with the seasons, with a mean annual position located slightly above the Equator, between 2° and 5°N.

This study tested the hypothesis that there was a northward shift in the median position of the ITCZ in the first decade of the …

Forging Blockchains: Spatial Production And Political Economy Of Decentralized Cryptocurrency Code/Spaces, Joe Blankenship

USF Tampa Graduate Theses and Dissertations

Cryptocurrencies and blockchains are increasingly used, implemented and adapted for numerous purposes; people and businesses are integrating these technologies into their practices and strategies, creating new political economies and spaces in and of everyday life. This thesis seeks to develop a foundation of geographic theory for the study of spatial production within and surrounding blockchain technologies focusing on acute studies of Bitcoin as cryptocurrency, Ethereum as digital marketplace, and their conditions of possibility as decentralized autonomous organizations. Utilizing concepts from Henri Lefebvre's Production of Space, this thesis situates blockchain technologies within the wider discussion about the political economy of …

Spatio-Temporal Dynamics Of Soil Composition And Accumulation Rates In Mangrove Wetlands, Joshua L. Breithaupt

USF Tampa Graduate Theses and Dissertations

Coastal wetlands are globally important environments for biogeochemical cycling and are the object of intensive research related to the sequestration and exchange of carbon with oceans, continents, and the atmosphere. Wetland soil core records of organic carbon (OC) provide insights about future ecosystem responses to global change by identifying temporal variability in the context of environmental changes including sea level rise (SLR), anthropogenic reductions in freshwater flow, and landscape-scale disturbance events. My studies of Gulf of Mexico mangroves involved the use of radiometrically-dated soil cores to identify spatial and temporal accumulation trends of various constituents including organic and carbonate carbon, …

Stormwater Infiltration And Groundwater Integrity: An Analysis Of Bmp Siting Tools And Groundwater Vulnerability, Kristopher Craig Gallagher

USF Tampa Graduate Theses and Dissertations

Nonpoint source pollution captured by urban stormwater runoff is the greatest challenge for surface water quality improvements. Computer-based design tools have been developed to help mediate this issue by guiding end users through the implementation of decentralized stormwater management. The majority of these tools focus on treatment via biofiltration, yet concern regarding this treatment regime is rising. Case studies from research past clearly indicate the susceptibility of groundwater to contamination from extensive anthropogenic activity at the surface. Contaminants, such as nitrates and pathogens, are not completely removed before runoff enters the underground watercourse. Additionally, national and state legislation, which explicitly …

Fatty Acid Biomarker Detection For Breast Cancer Using Differential Mobility Spectrometry With Non-Radioactive Ion Source, James Joseph Alberti

USF Tampa Graduate Theses and Dissertations

Differential Mobility Spectrometry (DMS) using a non-radioactive ion source (NRIS) is investigated as a possible medical diagnostic instrument for near real-time detection of breast cancer biomarkers. In previous clinical studies, concentrations of Linoleic, Palmitic and Stearic fatty acids have been observed at different levels in women with carcinoma breast cancer versus women with benign tumors or healthy women showing no signs of breast cancer. Present diagnostic methods require a biopsy of the suspect tissue and a microscopic lab analysis performed to determine its disease state. This process can take hours or days before the patient and doctor are informed of …

How Lessons From A Past Disaster Can Influence Resilience And Climate Adaptation In Broward County, Florida, Hannah Rose Torres

USF Tampa Graduate Theses and Dissertations

In the face of future uncertainties, many places are struggling with decisions about how to prepare for and adapt to climate change. The purpose of this research is to shed light on the concept of resilience, and uncover lessons for resilience-building exposed by a past disaster, Hurricane Wilma.

The dissertation begins with an introduction (Chapter 1) detailing the research problem, key terms and overall research design. The study was conducted in three distinct phases. The first phase (Chapter 2), explored the concept of resilience to understand how it was defined in three South Florida communities. Content analyses of city and …

Geographical Information Systems (Gis) Applied To Urban Nutrient Management: Data Scarce Case Studies From Belize And Florida, Charlotte Juliane Haberstroh

USF Tampa Graduate Theses and Dissertations

Nutrient inputs into the environment greatly impact urban ecosystems. Appropriate management strategies are needed to limit eutrophication of surface water bodies and contamination of groundwater. In many existing urban environments, retrofits or complete upgrades are needed for stormwater and/or wastewater infrastructure to manage nutrients. However, sustainable urban nutrient management requires comprehensive baseline data that is often not available. A Framework for Urban Nutrient (FUN) Management for Geographic Information Systems (GIS) was developed to specifically address those areas with limited data access. Using spatial analysis in GIS, it links water quality, land use, and socio-demographics, thereby reducing data collection and field-based …

Initial Comparative Empirical Usability Testing For The Collaborative Authentication System, Kim Bursum

USF Tampa Graduate Theses and Dissertations

The Collaborative Authentication (co-authentication) system is an authentication system that relies on some or all members of a pre-registered set of secure hardware tokens being concurrently present to an authentication server at the moment of authentication. Previous researchers have compared various embodiments of the co-authentication system to each other including using Quick Response (QR) codes/cellphone cameras and Near Field Communication (NFC) between tokens. This thesis concerns the initial design and implementation of empirical comparative testing mechanisms between one embodiment of the co-authentication system and other commonly used authentication systems. One contribution is the simulated standard user ID and password login …

Southern Ocean Transport By Combining Satellite Altimetry And Temperature/Salinity Profile Data, Michael Kosempa

USF Tampa Graduate Theses and Dissertations

Zonal geostrophic velocity fields above 1975 dbar have been estimated for the Southern Ocean from 2004 to 2014 based on sea surface topography observed by Jason altimetry and temperature/salinity measured by Argo autonomous floats. The velocity at 1000 dbar estimated has been validated against Argo drift trajectory at the same pressure level available from the Asia Pacific Data Research Center (APDRC). Errors in mapping of dynamic ocean topography, temperature, and salinity have been quantified using the Southern Ocean State Estimate (SOSE). Analysis of errors reveals significant correlations between depth-dependent and –independent contributions to the integrated transport. Further analysis revealed optimal …

New Reaction Discoveries In Gold Catalysis, Seyedmorteza Hosseyni

USF Tampa Graduate Theses and Dissertations

In this dissertation, gold catalyst was employed to catalyze intermolecular reactions. Intramolecular reactions were far more advanced than intermolecular reaction in gold catalysis. With finding suitable ligands for gold catalysts, we were able to develop several transformations to synthesize interesting building blocks in organic chemistry including: allenes, furans, spiros, oxepines, propargyl ethers and ketones. These functionalities were synthesized by the use of triazole-gold(I) catalyst. Triazole, as a ligand bond to gold, showed enhanced stability of the catalyst, which resulted in better yields. Gold(I)/(III) redox chemistry also used for cyclopropanol ring openings which resulted in synthesizing substituted ketones.

Land Use, Stream Stability, And Benthic Invertebrates In A Dry Forest Watershed Of Western Costa Rica, Jacqueline Ann Demko

USF Tampa Graduate Theses and Dissertations

There is a paucity of data on dry forests, the most threatened biome in the tropics. The Nandamojo is a tropical dry forest watershed in Western Costa Rica that has been impacted by varying degrees of human induced modifications. This research was conducted to examine the influence of land use and channel characteristics on invertebrate communities within a sub basin of the Nandamojo watershed. This study addressed three hypotheses: (1) sites with low tree cover and small riparian buffer zones will have high erosion, (2) macroinvertebrate abundance will be lower at sites with low channel stability values, and (3) benthic …

Effects Of Anthropogenic Activity On The Green Swamp Preserve Ecosystem, Barbara Ann Nordheim-Shelt

USF Tampa Graduate Theses and Dissertations

The Green Swamp Preserve is a large geographic area that has sustained many changes since Europeans settled in Florida. There has been little published research on the impacts of anthropogenic activity on this system. This thesis research seeks to document more recent changes in the Green Swamp and to evaluate the effects of various human activities on the system. The study period is from 1985 to 2015. For this time period changes in land use and landcover were examined using neural network classifications. Changes in vegetation health were evaluated by examining Normalized Difference Vegetation Index (NDVI) and Green Vegetation Index …