Physical Sciences and Mathematics Commons^™

The Hopf Fibration And Encoding Torus Knots In Light Fields, John Vincent Waite

UNLV Theses, Dissertations, Professional Papers, and Capstones

The first sections of this thesis explore a construction of electromagnetic fields first proposed by Bateman and recently rediscovered and expanded upon. With this powerful and elegant tool, I show that it is possible to construct families of EM fields that have a common topological structure that is preserved throughout time. This topological structure, known as the Hopf fibration, has been found to manifest itself in many areas of physics. Due to its utility, I have made a detailed study of it. The final section of this thesis develops an algorithm to parameterize a closed, bounded, and oriented surface that …

Is Being Green, White? A Critical Ethnographic Study Of Social Norms In Conservation, Heather Whitesides

UNLV Theses, Dissertations, Professional Papers, and Capstones

Attempts to measure and implement conservation norms have consistently upheld and promoted the dominant culture’s practices and beliefs. This has led to oppression of non-dominant populations, thereby hindering these populations’ access to various opportunities to participate in conservation based activities. This has historically, and still today, led to the segregation of non-dominant populations from environmental participation and has misrepresented their beliefs and actions relative to definitions of conservation citizenship and in the broader literature on conservation, conservation measurements, outdoor recreation, and pro-environmental behavior.

This research sought to extend the existing literature on conservation, specifically on the measurements of recreation practices …

Strategic Molecular Design To Engineer The Electron Affinity Of Self-Assembling Organic Semiconductors, Kelly Nicole Zaugg

UNLV Theses, Dissertations, Professional Papers, and Capstones

Development of electron-accepting (n-type) semiconductors used in organic photovoltaic cells and field effect transistors has been an area of research with less advancement compared to their electron-donating (p-type) counterparts. Currently, the highest performing n-type semiconductor is a fullerene-based derivative (PCBM) with a favorable ELUMO of -4.08 eV. However, PCBM has limited absorption in the visible region and fixed electron affinity. This work focuses on the development of self-assembling n-type materials with controllable electronic properties by strategically lowering ELUMO to a level comparable to PCBM. Molecular design follows an acceptor-acceptor'-acceptor (A-A'-A) configuration; with A being two 2,3-dioctyloxyphenazine substituents connected to A’ …

Electrochemical Studies Of Copolymers Of 3- Phenyl[5]Ferrocenophane-1,5-Dimethylene And Various Para-Substituted N-Phenylmaleimides, Henry Marshall Thomas

Electronic Theses & Dissertations

Ferrocene is an organometallic compound that consists of an iron atom sandwiched between two cyclopentadienyl rings. It has well understood redox properties and has been extensively studied making it useful in electrical systems. In this research alternating copolymers were synthesized via free radical polymerization from 3-phenyl[5]ferrocenophane-1,5-dimethylene and various para-substituted N-phenylmaleimides. Copolymers between this ferrocenophane and N-substituted maleimides have shown interesting electrical properties and the potential for charge transfer interactions between ferrocene and maleimide moieties. In this work, four new polymers were synthesized with differing electron withdrawing or donating groups on the para-position of the N-phenylmaleimide in order to influence potential …

Biosensors Derived From Copolymers Of Vinylferrocene With Various Para Substituted Phenylmaleimides, Nawrah Fahad Alghamdi

Electronic Theses & Dissertations

Five copolymers were synthesized from vinylferrocene with N-(4-

methoxyphenyl)maleimide, N-(4-methylphenyl)maleimide, N-phenylmaleimide, N-

(4-acetylphenyl)maleimide, and N-(4-cyanophenyl)maleimide. The resulting

copolymers were characterized by gel permeation chromatography, IR spectroscopy

and NMR spectroscopy. Thermal characterization of the copolymers included DSC

and TGA. The copolymers were also characterized electrochemically by cyclic

voltammetry in methylene chloride solutions and as a thin film in aqueous

electrolytes. As a thin film, each copolymer showed changes in oxidation potential

with different electrolytes (NaCl, NaNO3, NaClO4, and Na2SO4). These materials

were also tested as biosensors for hydrogen peroxide and dopamine, and compared to

polyvinyl ferrocene. Each material exhibited similar sensitivity …

Electrospun Nanofibers Of Metal Oxides For Energy Storage Applications, Sara Alkhalaf

Electronic Theses & Dissertations

Super capacitors are considered the most prominent and efficient energy storage devices, next to lithium ion batteries due to their high power densities, fast charge-discharge capabilities and long cyclibility. Super capacitors possess high power density in comparison to batteries and these are able to solve the increasing demand for energy in small consumer products, electrical vehicles and devices where quick power delivery is highly desired. Super capacitors are classified into two categories based on their charge storage mechanism. The first group capacitors are called electrical double-layer capacitors (EDLCs), where the charge is stored at the interface. The second group is …

Effect Of Surfactant On Structural And Electrochemical Properties Of Nickel Oxide, Muidh Albalawi

Electronic Theses & Dissertations

Today, the increasing demand for energy in the world has led to a focus on efficient and low cost energy storage devices. Many essential energy sources take a significant number of forms, including atomic energy and conventional sources, such as petroleum, coal and natural gas. Recently, super-capacitors have attracted research due to their high power densities, quick charge-discharge and long life cycles. The objective of this thesis is to alter the morphological structure of nickel oxide (NiO) utilizing different surfactants and furthermore to analyze the impact of these surfactants on the electrochemical properties of the nickel oxide. The unlimited applications …

Teaching Numerical Methods In The Context Of Galaxy Mergers, Maria Kourjanskaia

Physics

Methods of teaching numerical methods to solve ordinary differential equations in the context of galaxy mergers were explored. The research published in a paper by Toomre and Toomre in 1972 describing the formation of galactic tails and bridges from close tidal interactions was adapted into a project targeting undergraduate physics students. Typically undergraduate physics students only take one Computational Physics class in which various techniques and algorithms are taught. Although it is important to study computational physics techniques, it is just as important to apply this knowledge to a problem that is representative of what computational physics researchers are investigating …

Biodiversity Prioritization: A Comparison Of Data Types, Kari Norman

Undergraduate Honors Capstone Projects

The identification of important areas for biodiversity is essential for effective allocation of limited conservation resources. Prioritizing regions for conservation based on biodiversity is typically done using global biodiversity maps created using range map data for one or more taxa. While the use of range maps makes pragmatic sense since large-scale survey data is rarely available, it is important to understand the sensitivity of the results to the use of range map data. We studied how prioritizations may change between data types using the North American Breeding Bird survey (BBS) and BirdLife International range maps as a comparison case study. …

The Size And Shape Of The Milky Way Disc And Halo From M-Type Brown Dwarfs In The Borg Survey., Isabel Van Vledder, Dieuwertje Van Der Vlugt, Benne W. Holwerda, M. A. Kenworthy, R. J. Bouwens, M. Trenti

Faculty and Staff Scholarship

We have identified 274 M-type brown dwarfs in the Hubble Space Telescope's Wide Field Camera 3 pure parallel fields from the Brightest of Reionizing Galaxies (BoRG) survey for high-redshift galaxies. These are near-infrared observations with multiple lines of sight out of our Milky Way. Using these observed M-type brown dwarfs, we fitted a Galactic disc and halo model with a Markov chain Monte Carlo analysis. This model worked best with the scalelength of the disc fixed at h = 2.6 kpc. For the scaleheight of the disc, we found z0=0.29+0.02−0.019 z0=0.29−0.019+0.02 kpc and for the central number density, ρ0=0.29+0.20−0.13 ρ0=0.29−0.13+0.20 …

Characterizing The Earliest Stages Of Partial Melting: A Study Of The Pyrometamorphic Aureole Of Miocene Mt. Perkins Pluton, Northwest Arizona, Mathew Beshears

UNLV Theses, Dissertations, Professional Papers, and Capstones

Partial melting is an important process in the evolution of continental crust. Due to its progressive nature, evidence of the early stages of partial melting is often overprinted by later, advanced stages of partial melting. Experimental work has provided a model for the early stages of partial melting, but is limited to timescales of hours to weeks. Pyrometamorphic environments within the contact aureole of mafic intrusions provide natural laboratories for the study of the earliest stages of partial melt production on geologic time scales of 102 collected along two traverses of the tilted pyrometamorphic aureole of the Mt. Perkins pluton …

Direct Dissolution And Electrochemical Investigation Of Cerium And Uranium In Ionic Liquid, Janelle Droessler

UNLV Theses, Dissertations, Professional Papers, and Capstones

The solubility, coordination and speciation of f-elements in ionic liquids (ILs) has been the focus of numerous studies because the purely ionic systems have unique physical properties that can be exploited in comparison to aqueous, organic, or molten salt systems. Ionic liquids are thermally stable, have negligible vapor pressure, and are electrochemically stable at negative potentials that encompass the reduction potential of actinide species. Literature has suggested that the properties of ILs could potentially be utilized in the nuclear fuel cycle for separations and reprocessing. However, the solubility of f-elements in ILs has been significantly lower compared to traditional solvents. …

A Study On Automated Process For Extracting White Blood Cellular Data From Microscopic Digital Injured Skeletal Muscle Images, Bibek Karki

UNLV Theses, Dissertations, Professional Papers, and Capstones

Skeletal muscle injury is one of the common injuries caused by high-intensity sports activities, military related works, and natural disasters. In order to discover better therapies, it is important to study muscle regeneration process. Muscle regeneration process tracking is the act of monitoring injured tissue section over time, noting white blood cell behavior and cell-fiber relations. A large number of microscopic images are taken for tracking muscle regeneration process over multiple time instances. Currently, manual approach is widely used to analyze a microscopic image of muscle cross section, which is time consuming, tedious and buggy.

Automation of this research methodology …

Water Balance And Moisture Dynamics Of An Arid And Semi-Arid Soil: A Weighing Lysimeter And Field Study, Jeremy E. Koonce

UNLV Theses, Dissertations, Professional Papers, and Capstones

Semi-arid and arid environments are characterized by low precipitation and high evapotranspiration (ET), leaving little water available for discharge into surface water bodies and groundwater recharge. For these water-limited environments, understanding the relationships between precipitation, ET, and soil moisture is critical. These relationships not only affect water resources in these increasingly populated regions but are also necessary to predict the impact of climate change on semi-arid and arid ecosystems.

The overall goal of this dissertation was to shed light on the quantitative relationships between precipitation, evaporation, ET and soil moisture dynamics in an arid and a semi-arid environment. A three-step …

Mcnp6 Computational-Based Sensitivity Propagation Analysis Of Continuous Neutron Cross-Sections Using The Godiva (Hmf-001) And The Godiver (Hmf-004) Benchmark Criticality Study Cases, Lawrence James Lakeotes

UNLV Theses, Dissertations, Professional Papers, and Capstones

There has been a reduction in funding for theoretical and applied research for improving the nation's database of continuous neutron cross-sections at BNL-NNDC. From 1940 through the late 1980s, research and applied development produced volumes of reliable neutron continuous cross-sections for many isotopes. Currently, the cross-section work has been mainly computational. The focus of this research is mainly centered on the requirements for improving thermal cross-sections to support reactor operations and fuel storage. The research efforts will also helpfully aid in the fast fission spectrum in order to support fast reactor designs for improving safety analysis and feedback coefficients.

This …

Efficient Algorithms For Clustering Polygonal Obstacles, Sabbir Kumar Manandhar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Clustering a set of points in Euclidean space is a well-known problem having applications in pattern recognition, document image analysis, big-data analytics, and robotics. While there are a lot of research publications for clustering point objects, only a few articles have been reported for clustering a given distribution of obstacles. In this thesis we examine the development of efficient algorithms for clustering a given set of convex obstacles in the 2D plane. One of the methods presented in this work uses a Voronoi diagram to extract obstacle clusters. We also consider the implementation issues of point/obstacle clustering algorithms.

Neutron-Gamma Discrimination In Elpasolite Scintillator Detector, Brittany Morgan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Existing nuclear stockpiles and weapons-making capabilities imperil the global community. Current nonproliferation efforts involve the research and development of newer, more efficient detection systems that can be deployed for the interdiction and monitoring of special nuclear materials (SNM). Spontaneous and induced fission events in SNM produce neutrons and gamma rays, which can be detected and analyzed, in particular, using scintillator detectors. Various electronic data acquisition systems and data analysis methods have been employed to record and characterize neutron and photon signatures. The goal of this thesis is to develop a new method of discrimination between neutrons and photons in the …

Parallel Static Object Detection, Tirambad Shiwakoti

UNLV Theses, Dissertations, Professional Papers, and Capstones

The need for parallelism is growing with the broadening of computing in the real world where computing is an integral part of any field. In the early days of computing, adding transistors to the CPU could solve computation complexity. This is not the case now, where we can no longer advance the hardware capabilities at the pace of the advancement of computing problems. One of the fields which is intensive in computation is image processing. If it were just for one frame of an image, we could cope with the computation overhead. When the need is to compute video frames, …

Impacts To Phytoplankton After The Establishment Of Quagga Mussels In Lake Mead, Nevada, Warren Bruce Turkett

UNLV Theses, Dissertations, Professional Papers, and Capstones

Quagga mussels (Dreissena rostriformis bugensis) are an invasive species that were discovered in Lake Mead in January of 2007, and rapidly spread throughout the lake. Quagga mussels are about the size of a fingernail, but are known to clog pipes, damage infrastructure and alter ecosystems. In large numbers, mussels can have a dramatic impact on an ecosystem by reducing the phytoplankton and potentially increasing toxin producing cyanobacteria. This research analyzed data collected from three separate basins in Lake Mead to determine if water quality characteristics that are commonly impacted by invasive mussels have changed. Transparency, chlorophyll-a, phytoplankton and zooplankton samples …

Innovative Fiber Optic/Thin Film Photovoltaic Systems: Adequately Distributing Daylight While Harvesting Energy, Sean Steven Zurko

UNLV Theses, Dissertations, Professional Papers, and Capstones

On any given year, Las Vegas will be exposed to an average of 85% sunlight during typical daylight hours, while averaging seven peak hours a day. That alone makes Las Vegas a prime candidate for renewable solar energy systems (Solar Direct, 2016). By implementing fiber optics into office buildings in conjunction with thin-film photovoltaics, interior spaces have the potential to be adequately illuminated while simultaneously harvesting electricity. The study will be conducted through analysis and experimental field research with the intent of generating physical data, demonstrating that a hybrid fiber optic - photovoltaic system can at minimum match recommended foot-candle …

Understanding The Optical Properties Of Ambient Sub-And Supermicron Particulate Matter: Results From The Cares 2010 Field Study In Northern California, Christopher D. Cappa, Katheryn R. Kolesar, Xiaolu Zhang, Dean B. Atkinson, Mikhail S. Pekour, Rahul A. Zaveri, Alla Zelenyuk, Qi Zhang

Chemistry Faculty Publications and Presentations

Measurements of the optical properties (absorption, scattering and extinction) of PM1, PM2.5 and PM10 made at two sites around Sacramento, CA, during the June 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES) are reported. These observations are used to establish relationships between various intensive optical properties and to derive information about the dependence of the optical properties on photochemical aging and sources. Supermicron particles contributed substantially to the total light scattering at both sites, about 50 % on average. A strong, linear relationship is observed between the scattering Ångström exponent for PM10 and the fraction of the scattering that is …

Experimental And Computational Studies Of Cortical Neural Network Properties Through Signal Processing, Wesley Patrick Clawson

Graduate Theses and Dissertations

Previous studies, both theoretical and experimental, of network level dynamics in the cerebral cortex show evidence for a statistical phenomenon called criticality; a phenomenon originally studied in the context of phase transitions in physical systems and that is associated with favorable information processing in the context of the brain. The focus of this thesis is to expand upon past results with new experimentation and modeling to show a relationship between criticality and the ability to detect and discriminate sensory input. A line of theoretical work predicts maximal sensory discrimination as a functional benefit of criticality, which can then be characterized …

Isotopic Identification Of Multiple Contributors Of Metal Ions In Mississippi Valley-Type Ore Deposits Along The Cincinnati Arch In South-Central Kentucky, William Travis Garmon

Graduate Theses and Dissertations

Mississippi Valley-Type (MVT) ores are economically-viable deposits of sulfide minerals, often dominated by sphalerite (zinc-sulfide) in carbonate facies, and galena (lead-sulfide) in siliciclastic facies. MVT ores precipitate from migrating fluids, which carry base metals often complexed with chlorine ions within a basinal brine. This study identifies metal-contributing source-regions of the Burkesville MVT deposit using Pb-isotope ratios within sphalerite samples collected from the Burkesville deposit. The deposit is found in south-central Kentucky within the Middle-Tennessee ore district along the crest of the Cincinnati Arch, which is the anticlinal divide between the Appalachian Basin and the Illinois Basin. Competing theories argue that …

Stratigraphic Interpretation And Reservoir Implications Of The Arbuckle Group (Cambrian-Ordovician) Using 3d Seismic, Osage County, Oklahoma, Ryan Marc Keeling

Graduate Theses and Dissertations

The Arbuckle Group in northeastern Oklahoma consists of multiple carbonate formations, along with several relatively thin sandstone units. The group is a part of the “Great American Carbonate Bank” of the mid-continent and can be found regionally as far east as the Arkoma Basin in Arkansas, and as far west as the Anadarko Basin in Oklahoma. The Arbuckle is part of the craton-wide Sauk sequence, which is both underlain and overlain by regional unconformities.

Arbuckle is not deposited directly on top of a source rock. In order for reservoirs within the Arbuckle to become charged with hydrocarbons, they must be …

Statistical Analysis Of Fluvial Channel Belts, Kyle Ryan Spencer

Graduate Theses and Dissertations

As meandering rivers laterally migrate over time, they build channel belts. The accumulation of all previous flow paths creates the channel belt. To better understand these ancient rivers, modern river systems are being mapped to find statistical relationships between current flow path and the channel belt of river systems. It is important to examine a wide range of systems in terms of age, size, and location. The rivers are being mapped using an ImageJ, interpretations from Saucier (1994) and Google Earth. Three channel belt morphologies are mapped for 15 modern channel belts; the width of the river in relation to …

The Role Of Hydrologic Regimes In Driving Morphologic Divergence And The Trait Compositions Of Fish Assemblages, Lindsey A. Bruckerhoff

Graduate Theses and Dissertations

The hydrologic regime is an important determinant of the ecological integrity of a stream. Hydrologic regimes are defined by the magnitude, timing, frequency, rate of change, and duration of high and low flow events and capture long term patterns of variability and predictability of water movement in a stream. Flow regimes influence many aspects of the biophysical environment in lotic systems; therefore organisms have adapted to natural flow patterns. We investigated how fish have adapted to flow regimes at both a population and community level. In the first study presented in this thesis, we hypothesized fish exhibit phenotypic divergence to …

Semantic Proximity Search On Graphs With Metagraph-Based Learning, Yuan Fang, Wenqing Lin, Vincent W. Zheng, Min Wu, Kevin Chen-Chuan Chang, Xiao-Li Li

Research Collection School Of Computing and Information Systems

Given ubiquitous graph data such as the Web and social networks, proximity search on graphs has been an active research topic. The task boils down to measuring the proximity between two nodes on a graph. Although most earlier studies deal with homogeneous or bipartite graphs only, many real-world graphs are heterogeneous with objects of various types, giving rise to different semantic classes of proximity. For instance, on a social network two users can be close for different reasons, such as being classmates or family members, which represent two distinct classes of proximity. Thus, it becomes inadequate to only measure a …

On Unravelling Opinions Of Issue Specific-Silent Users In Social Media, Wei Gong, Ee-Peng Lim, Feida Zhu, Pei Hua Cher

Research Collection School Of Computing and Information Systems

Social media has become a popular platform for people toshare opinions. Among the social media mining researchprojects that study user opinions and issues, most focus onanalyzing posted and shared content. They could run into thedanger of non-representative findings as the opinions of userswho do not post content are overlooked, which often happensin today’s marketing, recommendation, and social sensing research.For a more complete and representative profiling ofuser opinions on various topical issues, we need to investigatethe opinions of the users even when they stay silent onthese issues. We call these users the issue specific-silent users(i-silent users). To study them and their …

Learning To Rank For Bug Report Assignee Recommendation, Yuan Tian, Withthige Dinusha Ruchira Wijedasa, David Lo, Claire Le Goues

Research Collection School Of Computing and Information Systems

Projects receive a large number of bug reports, and resolving these reports take considerable time and human resources. To aid developers in the resolution of bug reports, various automated techniques have been proposed to identify and recommend developers to address newly reported bugs. Two families of bug assignee recommendation techniques include those that recommend developers who have fixed similar bugs before (a.k.a. activity-based techniques) and those recommend suitable developers based on the location of the bug (a.k.a. location-based techniques). Previously, each of these techniques has been investigated separately. In this work, we propose a unified model that combines information from …

Deeper Look Into Bug Fixes: Patterns, Replacements, Deletions, And Additions, Mauricio Soto, Ferdian Thung, Chu-Pan Wong, Claire Le Goues, David Lo

Research Collection School Of Computing and Information Systems

Many implementations of research techniques that automatically repair software bugs target programs written in C. Work that targets Java often begins from or compares to direct translations of such techniques to a Java context. However, Java and C are very different languages, and Java should be studied to inform the construction of repair approaches to target it. We conduct a large-scale study of bugfixing commits in Java projects, focusing on assumptions underlying common search-based repair approaches. We make observations that can be leveraged to guide high quality automatic software repair to target Java specifically, including common and uncommon statement modifications …