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Articles 1 - 30 of 41
Full-Text Articles in Physical Sciences and Mathematics
A Reasoning Framework For Dependability In Software Architectures, Tacksoo Im
A Reasoning Framework For Dependability In Software Architectures, Tacksoo Im
All Dissertations
The degree to which a software system possesses specified levels of software quality attributes, such as performance and modifiability, often have more influence on the success and failure of those systems than the functional requirements. One method of improving the level of a software quality that a product possesses is to reason about the structure of the software architecture in terms of how well the structure supports the quality. This is accomplished by reasoning through software quality attribute scenarios while designing the software architecture of the system.
As society relies more heavily on software systems, the dependability of those systems …
Debugging Techniques For Locating Defects In Software Architectures, Kyungsoo Im
Debugging Techniques For Locating Defects In Software Architectures, Kyungsoo Im
All Dissertations
The explicit design of the architecture for a software product is a well established part of development projects. As the software architecture descriptions are becoming larger and more complex, there is more likelihood of defects being present in the software architecture. Studies have shown that a defect in the software architecture that has propagated to the development phase is very expensive to fix. To prevent such propagation of defects, this research proposes to provide debugging support for software architecture design.
Debugging is commonly used in programming languages to effectively find the cause of a failure and locate the error to …
Design And Regioselective Synthesis Of Two And Three-Pronged C60 Fullerene Derivatives And Their Applications In Molecular Electronics, Angy Ortiz-Hernandez
Design And Regioselective Synthesis Of Two And Three-Pronged C60 Fullerene Derivatives And Their Applications In Molecular Electronics, Angy Ortiz-Hernandez
All Dissertations
Since the introduction of semiconductors in the second half of the 20th century, advancements in electronics and technology have been tremendous. In particular, the rapid development of silicon-based computer chip technology and miniaturization of electronic components has been tremendous. Since silicon-based materials have a limit in terms of size, scientists proposed that individual molecules could behave as single electronic components for high degree of miniaturization.
Given that the molecules of interest must have dimensions on the nanometer scale, be able to bind to the electrode surface and have electron donor-acceptor properties, C60 fullerene has been a prime candidate for …
Novel Neomycin Conjugates For Multi-Recognition Of Nucleic Acids, Albert Willis
Novel Neomycin Conjugates For Multi-Recognition Of Nucleic Acids, Albert Willis
All Dissertations
Neomycin is an aminoglycoside antibiotic known for its high affinity for RNA duplex structures. Recent developments from our labs have indicated that aminoglycoside binding is not limited to RNA, but to nucleic acids that, like RNA, adopt conformations similar to A-form. Our group sought to further expand the utility of aminoglycoside binding to B-DNA structures by conjugating neomycin, an aminoglycoside antibiotic, with the B-DNA minor groove binding ligand Hoechst 33258. Envisioning a dual groove-binding mode, we have extended the potential recognition process to include a third, intercalative moiety. Furthermore, we observe remarkable recognition of such conjugates with RNA duplex. Spectroscopic …
A Framework For Virtual Device Driver Development And Virtual Device-Based Performance Modeling, Zachary Jones
A Framework For Virtual Device Driver Development And Virtual Device-Based Performance Modeling, Zachary Jones
All Dissertations
Operating system virtualization tools such as VMWare, XEN, and Linux KVM export only minimally capable SVGA graphics adapters. This paper describes the design and implementation of system
that virtualizes high-performance graphics cards of arbitrary design to support the construction of authentic device drivers. Drivers written for the virtual cards can be used verbatim, without special function calls or kernel modifications, as drivers for real cards, should real cards of the same design exist. While this allows for arbitrary design, it is not able to model performance characteristics. We describe a new kernel system that allows for arbitrarily changing the performance …
Modeling The Galactic 511 Kev Positron Annihilation Emission, Production, And Propagation, Bethany Johns
Modeling The Galactic 511 Kev Positron Annihilation Emission, Production, And Propagation, Bethany Johns
All Dissertations
The Galactic 511 keV positron annihilation emission has a strong bulge component to the emission and a weak disk component. The bulge emission is about 1.4 -- 6 times as the disk emission. The bulge emission is defined to be a diffuse emission centered at the Galactic center and extends to about a FWHM of 8 degrees in Galactic longitude and latitude. An asymmetry has also been observed in the disk emission, where the negative longitudes are brighter than the positive longitudes by a factor of 1.8.
This research examines the morphology of the Galactic 511 keV positron annihilation emission …
Synthesis And Optical Properties Of Silver Nanostructures, John Heckel
Synthesis And Optical Properties Of Silver Nanostructures, John Heckel
All Dissertations
Silver nanoparticles interact with light via the excitation of plasmon resonances that are the collective oscillations of the free electron density. This excitation represents the most efficient mechanism for the interaction of light with matter and therefore the nanoparticles are of great interest for both fundamental and practical points of view. In the following dissertation, silver nanoparticles, core-shell nanoparticles, and silver nanoparticle clusters were synthesized and there optical properties were investigated.
Chapter 1 contains general background information about the optical properties of bulk and silver nanoparticles. It also contains a concise description of two of my collaborative projects that did …
A Study Of African American Forest Landowners In South Carolina: Implications For Land Ethic And Forest Stewardship, Keenan Adams
A Study Of African American Forest Landowners In South Carolina: Implications For Land Ethic And Forest Stewardship, Keenan Adams
All Dissertations
African Americans account for a significant proportion of South Carolina`s
population but reportedly own a disproportionally smaller amount of land. Research indicates that landowners who hold significant sources of sustainable wealth and power can dramatically increase their quality of life and ultimately that of their communities. Current land loss trends for African Americans are increasing at an alarming rate, which may have larger social implications for this traditionally underserved population. The remaining African American landowners are a rapidly declining group, due to an assortment of factors (e.g., age, heirs property). Understanding the experiences of the residual African American forest landowners …
Synthesis Of Trimetallic Nitride Endohedral Metallofullerene Derivatives For Enhanced Solar Energy Conversion, Julio Pinzon Joya
Synthesis Of Trimetallic Nitride Endohedral Metallofullerene Derivatives For Enhanced Solar Energy Conversion, Julio Pinzon Joya
All Dissertations
The preparation and electrochemical properties of donor - acceptor systems based on trimetallic nitride endohedral metallofullerenes (TNT-EMFs) for enhanced solar energy conversion is described. It was found that TNT-EMFs have an enhanced ability to stabilize charge separated states formed upon light irradiation when compared to empty cage fullerene analogues. The influence of the linker connecting the donor and acceptor moieties was studied in two different systems. Optimal conditions for preparing cyclopropanated Bingel-Hirsch derivaties of the most common TNT-EMFs were found; this functionalization approach is a very useful alternative to the 1,3-dipolar cycloaddition reactions that yield pyrrolidine derivatives, because the latter …
Evolutionary Strategies For Data Mining, Rose Lowe
Evolutionary Strategies For Data Mining, Rose Lowe
All Dissertations
Learning classifier systems (LCS) have been successful in generating rules for solving classification problems in data mining. The rules are of the form IF condition THEN action. The condition encodes the features of the input space and the action encodes the class label. What is lacking in those systems is the ability to express each feature using a function that is appropriate for that feature. The genetic algorithm is capable of doing this but cannot because only one type of membership function
is provided. Thus, the genetic algorithm learns only the shape and placement of the membership function, and in …
Preparation And Studies Of Fluorescent Carbon Nanomaterials, Xin Wang
Preparation And Studies Of Fluorescent Carbon Nanomaterials, Xin Wang
All Dissertations
There have been rapid advances in the development and applications of semiconductor quantum dots (QDs) represented by CdSe/ZnS. However, a serious limitation of these QDs is the necessary use of toxic heavy metals. Fluorescent 'carbon dots' (surface passivated carbon nanoparticles) are developed as alternative to classical semiconductor QDs.
The carbon dots could be made to be highly fluorescence, with emission quantum yields close to 60%. Their optical properties resemble bandgap transitions found in nanoscale semiconductors, suggesting that carbon particles at the nanoscale acquire essentially semiconductor-like characteristics.
The fluorescence in carbon dots could be quenched efficiently by electron acceptor or donor …
Uncertainty Of Dimensional Measurments Obtained From Self-Initialized Instruments, Vincent Lee
Uncertainty Of Dimensional Measurments Obtained From Self-Initialized Instruments, Vincent Lee
All Dissertations
Precision dimensional measurement instruments often contain sensors that can only measure displacement of a moving body from some reference position. In order to measure the length of an object they often require a calibrated artifact to initialize their measurement sensors so that they may provide an absolute measurement instead of displacement. Instruments which can realize a null value, i.e. zero length, don't require one; however instruments which can't need to reference an object of known size. These calibration artifacts also serve as part of the chain of metrological traceability.
The group of instruments presented in this dissertation can self-initialize by …
Poly (Acrylonitrile-Co-1-Vinylimidazole): A New Melt Processable Carbon Fiber Precursor, Wenjin Deng
Poly (Acrylonitrile-Co-1-Vinylimidazole): A New Melt Processable Carbon Fiber Precursor, Wenjin Deng
All Dissertations
Carbon fiber polymer composites have attracted worldwide interest in sporting goods and aerospace industries due to their excellent specific strength, stiffness and lightweight. The replacement of solution-spinning process by melt-spinning process is one of the major approaches to make cost effective carbon fiber. In recent years, researchers have explored the possibilities to synthesize melt processable carbon fiber precursors, but their thermal stabilization is still a challenge. The goal for this research project is to prepare melt processable carbon fiber precursors which have the capability of thermal stabilization. Acrylonitrile/1-vinylimidazole (AN/VIM) copolymers containing various mol% of VIM were synthesized by free radical …
Approximation Algorithms For Network Interdiction And Fortification Problems, Adam Whitley
Approximation Algorithms For Network Interdiction And Fortification Problems, Adam Whitley
All Dissertations
This dissertation discusses algorithms and results on several NP–hard graph problems which can all be classified as network interdiction and network fortification problems.
The first problem studied, the multiway cut problem, is a generalization of the well–studied s–t min–cut problem, in which we must remove a minimum–cost subset of edges from a graph so that r > 2 designated terminals become disconnected from each other. We investigate an approximation algorithm for general r with a relatively simple analysis guaranteeing an approximation ratio ≤ 1.4647 − epsilonr, where epsilonr is a small constant related to the number of terminals …
Gamma Ray Bursts As Probes Of Dust In The Evolving Universe, Adria Updike
Gamma Ray Bursts As Probes Of Dust In The Evolving Universe, Adria Updike
All Dissertations
Dust is ubiquitous in the universe. Understanding where it comes from and where we observe it can have major implications to all astronomical observations. In this study, we investigate how gamma ray bursts (GRBs) can be used as probes of dust in the evolving universe. Making the simplification that silicate dust comes from core collapse supernovae and that graphite dust is produced in the winds of low- to intermediate-mass stars, we present numerical simulations of the resulting dust evolution in GRB hosts and show how the SEDs evolve. Dust extinction laws are re-derived from scattering theory of small particles and …
Batch Testing, Adaptive Algorithms, And Heuristic Applications For Stable Marriage Problems, John Dabney
Batch Testing, Adaptive Algorithms, And Heuristic Applications For Stable Marriage Problems, John Dabney
All Dissertations
In this dissertation we focus on different variations of the stable matching (marriage) problem, initially posed by Gale and Shapley in 1962. In this problem, preference lists are used to match n men with n women in such a way that no (man, woman) pair exists that would both prefer each other over their current partners. These two would be considered a blocking pair, preventing a matching from being considered stable. In our research, we study three different versions of this problem.
First, we consider batch testing of stable marriage solutions. Gusfield and Irving presented an open problem in their …
Effects Of Imperviousness On Family Biotic Index Values In The Southern Appalachian Headwaters And Resulting Extension Education, Jon Calabria
All Dissertations
Clear, cool headwater streams in the mountains of North Carolina are inextricably linked to the surrounding landscape. Trickling perennial streams drain precipitation from their catchment and are capable of sustaining excellent water quality to support rich aquatic biodiversity that feeds and beneficially contributes to the stream network below. However, headwater ecosystems can be easily compromised by even seemingly insignificant anthropogenic impacts. Small headwater streams were not mapped until recently, and are now known to be ubiquitous. Although the NC Mountains contain some of the highest headwater streams densities in the nation, they remain very susceptible to changes in the catchments …
Internal Transitions In Nuclei And Applications To Astrophysics And Cosmochemistry, Joseph Johnson
Internal Transitions In Nuclei And Applications To Astrophysics And Cosmochemistry, Joseph Johnson
All Dissertations
In this dissertation I analyze internal transitions in nuclei and their potential effects on s-process branching and on accelerated β-decay in cosmochemical samples. To accomplish my analysis, I have constructed a number of computational tools, which I have publicly released or make available through this thesis. I apply my analysis to the question of s-process branching at 186Re and study the implications for the osmium isotopes in mainstream presolar SiC grains. My essential conclusion is that the problem of the large neutron flux inferred from the SiC osmium isotopic abundances cannot be solved by branching through an out-of-equilibrium isomer of …
Perfluoroalkyl Phosphonic And Phosphinic Acid Electrolytes For Proton Exchange Membrane Fuel Cells, Mahesha Herath
Perfluoroalkyl Phosphonic And Phosphinic Acid Electrolytes For Proton Exchange Membrane Fuel Cells, Mahesha Herath
All Dissertations
Perfluorinated sulfonic acid polymers have been considered as the state-of-art membrane materials for proton exchange membrane fuel cells. A major technical issue with these polymers is that they do not function well at temperatures above 80 °C and at low humidities. Therefore, research has been focused on developing PEM materials that can operate independent of hydration requirements. The operation of fuel cells at high temperature (e.g. 120 oC) increases fuel cell system efficiency due to faster electrode kinetics and better CO tolerance. This dissertation will describe a study of proton-transport rates and mechanisms under anhydrous and aqueous conditions using a …
Observing Co In Circumstellar Disks, Matthew Troutman
Observing Co In Circumstellar Disks, Matthew Troutman
All Dissertations
This dissertation includes high-resolution, near-infrared spectroscopy to study CO in circumstellar disks around Herbig Ae/Be stars. The velocity-resolved spectra was used to measure the distribution of gas in the circumstellar disk and thus determine the evolutionary state of the system. Near-infrared spectra were obtained on over 30 young circumstellar disks around Herbig Ae/Be stars to study the physical processes in the disk. The radial location of the CO emitting gas bears directly on the evolutionary state of the transition objects in the sample. This study included a detailed study of the debris disk star β Pictoris where the disk mass …
Event-Driven Similarity And Classification Of Scanpaths, Thomas Grindinger
Event-Driven Similarity And Classification Of Scanpaths, Thomas Grindinger
All Dissertations
Eye tracking experiments often involve recording the pattern of deployment of visual attention over the stimulus as viewers perform a given task (e.g., visual search). It is useful in training applications, for example, to make available an expert's sequence of eye movements, or scanpath, to novices for their inspection and subsequent learning. It may also be potentially useful to be able to assess the conformance of the novice's scanpath to that of the expert. A computational tool is proposed that provides a framework for performing such classification, based on the use of a probabilistic machine learning algorithm. The approach was …
A Computational Framework To Support The Automated Analysis Of Routine Electroencephalographic Data, William Pressly, Jr.
A Computational Framework To Support The Automated Analysis Of Routine Electroencephalographic Data, William Pressly, Jr.
All Dissertations
Epilepsy is a condition in which a patient has multiple unprovoked seizures which are not precipitated by another medical condition. It is a common neurological disorder that afflicts 1% of the population of the US, and is sometimes hard to diagnose if seizures are infrequent. Routine Electroencephalography (rEEG), where the electrical potentials of the brain are recorded on the scalp of a patient, is one of the main tools for diagnosing because rEEG can reveal indicators of epilepsy when patients are in a non-seizure state. Interpretation of rEEG is difficult and studies have shown that 20-30% of patients at specialized …
An Examination Of Heritage Resource Internship Experiences And Land Management Agency's Role In Inspiring Emerging Leaders, Carin Vadala
An Examination Of Heritage Resource Internship Experiences And Land Management Agency's Role In Inspiring Emerging Leaders, Carin Vadala
All Dissertations
To address the shortage of people seeking to fill employment vacancies, the land management agencies are using the Student Conservation Association (SCA) and internships as a means of recruiting the next generation of leaders. Yet little research has been conducted on internships in cultural and natural heritage resource parks. This study used a two-phase linear exploratory method to investigate the experiences of cultural and natural heritage resource interns. Additionally, the study sought to determine if and how internships shape vocational, recreational, social and personal identities concerning parks and protected areas. Using significant life experiences, environmental socialization and emerging adulthood theories, …
Chemical Modification And Biological Activity Exploration Of The Natural Product-Gossypol, Juanjuan Yin
Chemical Modification And Biological Activity Exploration Of The Natural Product-Gossypol, Juanjuan Yin
All Dissertations
Gossypol is a naturally occurring, highly colored yellow pigment indigenous to the small intercellular pigment glands of the cotton plant genus Gossypium, which is proposed to be part of plant's defense system. Gossypol is characterized by wide contraceptive, antiviral, anticancer and antifungal properties. However, the relatively high toxicity of gossypol precludes its application in medical therapy. For this reason the syntheses and tests of gossypol derivatives, have been tried to enable their application as drugs. In our study, gossypol based methylation, glycosylation and nanoconjugate reactions were explored. The gossypol derivatives were all fully characterized by NMR, MS, FT-IR, UV spectrometry, …
Novel Π-Conjugated Materials Plus Their Characterizations And Applications, Xiuxian He
Novel Π-Conjugated Materials Plus Their Characterizations And Applications, Xiuxian He
All Dissertations
The theme of this dissertation will focus on the syntheses and characterization of bipyridine (bipy) containing π-conjugated polymers (CPs). Specifically, poly(p-phenylene ethynylene), polyfluorene and poly(p-phenylene vinylene) derivatives have been prepared via Sonogashira coupling, Suzuki coupling and Heck coupling, respectively. Derivatives of poly(p-phenylene ethynylene), polyfluorene and poly(p-phenylene vinylene) are known to have applications in optical and electronic devices. Through this study, polymers condensed with bulky bipy-containing TAB as one of the copolymer units have shown increased solubility and diminished intrachain/interchain aggregation in solution and in film due to the effectiveness of TAB in controlling the relative orientations of individual polymer chains. …
Source Optimization In Abstract Function Spaces For Maximizing Distinguishability: Applications To The Optical Tomography Inverse Problem, Bonnie Jacob
All Dissertations
The focus of this thesis is to formulate an optimal source problem for the medical imaging technique of optical tomography by maximizing certain distinguishability criteria. We extend the concept of distinguishability in electrical impedance tomography to the frequency-domain diffusion approximation model used in optical tomography.
We consider the dependence of the optimal source on the choice of appropriate function spaces, which can be chosen from certain Sobolev or Lp spaces. All of the spaces we consider are Hilbert spaces; we therefore exploit the inner product in several ways. First, we define and use throughout an inner product on the Sobolev …
Virtual Organization Clusters: Self-Provisioned Clouds On The Grid, Michael Murphy
Virtual Organization Clusters: Self-Provisioned Clouds On The Grid, Michael Murphy
All Dissertations
Virtual Organization Clusters (VOCs) provide a novel architecture for overlaying dedicated cluster systems on existing grid infrastructures. VOCs provide customized, homogeneous execution environments on a per-Virtual Organization basis, without the cost of physical cluster construction or the overhead of per-job containers. Administrative access and overlay network capabilities are granted to Virtual Organizations (VOs) that choose to implement VOC technology, while the system remains completely transparent to end users and non-participating VOs. Unlike alternative systems that require explicit leases, VOCs are autonomically self-provisioned according to configurable usage policies. As a grid computing architecture, VOCs are designed to be technology agnostic and …
Understanding The Biological And Environmental Implications Of Nanomaterials, Sijie Lin
Understanding The Biological And Environmental Implications Of Nanomaterials, Sijie Lin
All Dissertations
The last two decades have witnessed the discovery, development, and large-scale manufacturing of novel nanomaterials. While nanomaterials bring in exciting and extraordinary properties in all areas of materials, electronics, mechanics, and medicine, they also could generate potential adverse effects in biological systems and in the environment. The currently limited application of nanomaterials in biological and ecological systems results from the insufficient and often controversial data on describing the complex behaviors of nanomaterials in living systems. The purpose of this dissertation intends to fill such a knowledge void with methodologies from the disciplines of biophysics, biology, and materials science and engineering. …
Creating A Biomedical Ontology Indexed Search Engine To Improve The Semantic Relevance Of Retreived Medical Text, William Taylor Ii
Creating A Biomedical Ontology Indexed Search Engine To Improve The Semantic Relevance Of Retreived Medical Text, William Taylor Ii
All Dissertations
Medical Subject Headings (MeSH) is a controlled vocabulary used by the National Library of Medicine to index medical articles, abstracts, and journals contained within the MEDLINE database. Although MeSH imposes uniformity and consistency in the indexing process, it has been proven that using MeSH indices only result in a small increase in precision over free-text indexing. Moreover, studies have shown that the use of controlled vocabularies in the indexing process is not an effective method to increase semantic relevance in information retrieval.
To address the need for semantic relevance, we present an ontology-based information retrieval system for the MEDLINE collection …
Self-Assembly Of Architecturally Complex Block Copolymers, Juan Hinestrosa
Self-Assembly Of Architecturally Complex Block Copolymers, Juan Hinestrosa
All Dissertations
The term self-assembly denotes the formation of complex structures from simpler building blocks, resembling the manner in which Nature generates functional systems. In this pursuit, block copolymers present a great opportunity to study the interactions, dynamics and self-assembly of soft matter. Block copolymers have the ability to self-assemble into thermodynamically stable microphase segregated domains of precise shape and size, which are controlled by the chemistry of the constituent blocks, their size and connectivity, temperature and solvent conditions. Specifically, in this body of work two different types of branched copolymers with polystyrene (PS) and polyisoprene (PI) constituents are studied. The complex …