Physical Sciences and Mathematics Commons^™

Propensity Score Methods : A Simulation And Case Study Involving Breast Cancer Patients., John Craycroft

Electronic Theses and Dissertations

Observational data presents unique challenges for analysis that are not encountered with experimental data resulting from carefully designed randomized controlled trials. Selection bias and unbalanced treatment assignments can obscure estimations of treatment effects, making the process of causal inference from observational data highly problematic. In 1983, Paul Rosenbaum and Donald Rubin formalized an approach for analyzing observational data that adjusts treatment effect estimates for the set of non-treatment variables that are measured at baseline. The propensity score is the conditional probability of assignment to a treatment group given the covariates. Using this score, one may balance the covariates across treatment …

Semi-Parametric Methods For Personalized Treatment Selection And Multi-State Models., Chathura K. Siriwardhana

Electronic Theses and Dissertations

This dissertation contains three research projects on personalized medicine and a project on multi-state modelling. The idea behind personalized medicine is selecting the best treatment that maximizes interested clinical outcomes of an individual based on his or her genetic and genomic information. We propose a method for treatment assignment based on individual covariate information for a patient. Our method covers more than two treatments and it can be applied with a broad set of models and it has very desirable large sample properties. An empirical study using simulations and a real data analysis show the applicability of the proposed procedure. …

Urban Flooding And Sewer Inundation On The University Of Louisville Belknap Campus., Justin T. Hall

Electronic Theses and Dissertations

Over the past few decades on the University of Louisville Belknap campus urban flooding has become more frequent as a result of surface water runoff and sewer inundation. This urban flooding is a result of ongoing watershed urbanization and rapid expansion of the local sewer system to accommodate the expanding city of Louisville. However little research has been conducted on this issue, despite continued flooding on and adjacent to campus. Using the EPA Storm Water Management Model (SWMM) we applied a dual drainage modeling approach that combines both surface and subsurface drainage data to produce a flood hydrograph at the …

Inference For A Zero-Inflated Conway-Maxwell-Poisson Regression For Clustered Count Data., Hyoyoung Choo-Wosoba

Electronic Theses and Dissertations

This dissertation is directed toward developing a statistical methodology with applications of the Conway-Maxwell-Poisson (CMP) distribution (Conway, R. W., and Maxwell, W. L., 1962) to count data. The count data for this dissertation exhibit three different characteristics: clustering, zero inflation, and dispersion. Clustering suggests that observations within clusters are correlated, and the zero inflation phenomenon occurs when the data exhibit excessive zero counts. Dispersion implies that the mean is greater/smaller than the variance unlike a Poisson distribution. The dissertation starts with an introduction of inference for a zero-inflated clustered count data in the first chapter. Then, it presents novel methodologies …

Chemoselective Reactions And Their Applications In Metabolite Isolation And Analysis., Sadakatali Shokatali Gori

Electronic Theses and Dissertations

Chemoselectivity is the preferential reaction of a reagent with a select functional group among other plausible reactions. This dissertation describes chemoselective reagents and methods explored to develop more accurate, efficient and high-throughput means to quantify metabolites containing either thiol, carboxylic acid or 1,2-diol moieties directly from biological mixtures. Chapter 1 discusses how dysregulation of thiol- or carboxylic acid-containing metabolites is either the cause or effect of cellular dysfunction. Quantifying such metabolites is important in discovery of pathways to understand etiology of diseases. Chapter 1 also discusses the need for sustainable syntheses using renewable resources and describes the traditional methods for …

A Cycle Generating Function On Finite Local Rings, Tristen Kirk Wentling

Graduate Theses/Dissertations

We say a function generates a cycle if its output returns the initial value for some number of successive applications of . In this thesis, we develop a class of polynomial functions for finite local rings and associated functions . We show that the zeros of one are precisely the fixed points of the other and that every ring element is either one of these fixed points or is in a cycle of fixed length equal to the order of 2 in the associated group of units. Particular emphasis is given to rings of integers modulo the square of a …

Increasing Solubility Of Active Pharmaceutical Ingredients In Topical Creams Using Soluplus®, Roni Balzam

Graduate Theses/Dissertations

More than 40% of new chemicals developed in the pharmaceutical industry have poor solubility in aqueous solutions. Active Pharmaceutical ingredients (API) cannot reach their molecular targets in the body if the drug remains undissolved in the gastrointestinal system. One way to approach this problem is by using solubilizing agents. One such agent is a thermo-responsive, tri-block co-polymer which is marketed as “Soluplus®" (SP) by BASF Corporation. A part of this project is to thoroughly characterize various phase properties of SP such as cloud points and gel points temperatures. In current application, SP was incorporated into the creams formulations as an …

Spatial Distribution And Geomorphic Factors Of Lead Contamination On Floodplains Affected By Historical Mining, Big Rover, S.E. Missouri, David Bower Huggins

Graduate Theses/Dissertations

Historical mining in the Old Lead Belt resulted in lead (Pb) contamination of floodplain soils for over 170 km along the Big River in southeastern Missouri. The overall pattern of contamination are understood. However, Pb distribution across floodplain surfaces has not been investigated at the scale needed for site-level remediation planning. The goal of this project is to examine spatial distribution of Pb with more detail and identify the role of geomorphic processes. Predictive models are needed to evaluate factors affecting Pb distribution such as elevation, distance from the channel, and geochemistry. This study evaluates Pb distribution at three ~1km …

A Geometric Approach To Ramanujan's Taxi Cab Problem And Other Diophantine Dilemmas, Zachary Kyle Easley

Graduate Theses/Dissertations

In 1917, the British mathematician G.H. Hardy visited the Indian mathematical genius Ramanujan in the hospital. The number of the taxicab Hardy arrived in was 1729. Ramanujan immediately recognized this as the smallest positive integer that can be expressed as the sum of two cubes in two essentially different ways. In this thesis, we use properties of conics and elliptic curves to investigate this problem, its generalization to fourth powers, and a Diophantine equation involving the distance of a point from the vertices of a regular tetrahedron (the latter extends work of Christina Bisges).

Evaluation Of Topic Models For Content-Based Popularity Prediction On Social Microblogs, Axel Magnuson

Boise State University Theses and Dissertations

Online social networks are an increasingly central medium of communication in the 21st century. We have seen a proliferation of competing social networks which differentiate themselves by serving different niches of communication. Among these, Twitter has risen to prominence as a leader among microblogging communities, characterized by publicly visible 140-character messages called tweets. The wide visibility of Twitter messages has enabled some users to curate large followings, and has facilitated content creators who wish to reach as many viewers as possible. Researchers have since investigated many methods for predicting which messages will become popular or even go viral on Twitter. …

On The Conjugacy Problem For Automorphisms Of Trees, Kyle Douglas Beserra

Boise State University Theses and Dissertations

In this thesis we identify the complexity of the conjugacy problem of automorphisms of regular trees. We expand on the results of Kechris, Louveau, and Friedman on the complexities of the isomorphism problem of classes of countable trees. We see in nearly all cases that the complexity of isomorphism of subtrees of a given regular countable tree is the same as the complexity of conjugacy of automorphisms of the same tree, though we present an example for which this does not hold.

Identification Of Small Endogenous Viral Elements Within Host Genomes, Edward C. Davis Jr.

Boise State University Theses and Dissertations

A parallel string matching software architecture has been developed (incorporating several algorithms) to identify small genetic sequences in large genomes. Endogenous viral elements (EVEs) are sequences originating in the genomes of viruses that have become integrated into the chromosomes of sperm or egg cells of infected hosts, and passed to subsequent generations. EVEs have been identified in all seven classes of viruses and in the species of all kingdoms of life. Viruses from groups V and VI are considered in this thesis, including HIV and Ebola, within host genomes ranging from bacteria to humans. This database of small endogenous viral …

Assessment Of American White Pelican Predation And Reproductive Success Of Walleye In The Tamarac River, Mn, Jake Graham

Biology Graduate Theses

The Tamarac River is a major tributary of the Red Lakes MN, which provides an economically important multispecies fishery. The river experiences spring spawning migrations of northern pike, walleye, and white suckers. However, limited data exists related to reproductive success of fishes in the river. Furthermore, in the previous decade large congregations of American white pelicans (AWPE) have been observed using the Tamarac River as a foraging ground each spring. Assessing reproductive success of fishes in the Tamarac River provides a more holistic understanding of fish ecology in the river and the importance of the Tamarac River to the Red …

High-Pressure Properties Of Several Narrow Bandgap Semiconductors From First-Principles Calculations, Andrew Michael Alvarado

UNLV Theses, Dissertations, Professional Papers, and Capstones

The electronic, thermodynamic, and structural properties of three semiconducting materials, ZnO, InN, and PbS, at high pressure are investigated utilizing first-principles calculations based on density function theory. The first two systems, ZnO and InN, crystalize as hexagonal structures at ambient conditions and transition to a cubic structure at higher pressures. The last system, PbS, is cubic at ambient conditions, but transitions to an orthorhombic structure at higher pressure. At ambient conditions, these materials are well known semiconductors with vast amount of research and a variety of wide ranging applications in electrical devices. However, there is a lack of understanding of …

On The Scattering Of An Acoustic Plane Wave By A Soft Prolate Spheroid, Joseph Michael Borromeo

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis solves the scattering problem in which an acoustic plane wave of propagation number K1 is scattered by a soft prolate spheroid. The interior field of the scatterer is characterized by a propagation number K2, while the field radiated by the scatterer is characterized by the propagation number K3. The three fields and their normal derivatives satisfy boundary conditions at the surface of the scatterer. These boundary conditions involve six complex parameters depending on the propagation numbers. The scattered wave also satisfies the Sommerfeld radiation condition at infinity. Through analytical methods, series representations are constructed for the interior field …

A Case For Chiral Contributions To Nondipole Effects In Photoionization Using Linearly Polarized Soft X-Rays, Kyle Patrick Bowen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Modelling angular distributions of photoelectrons requires making accurate approximations of both the incoming light and the behavior of bound electrons. The experimental determination of photoelectron angular distributions is crucial to the development of accurate theoretical models governing the light-matter interaction. To date, many models have relied upon the dipole approximation, which assumes a constant electric field as the source of ionization. Despite knowing that the dipole approximation would break down as photon energy increased, the precise limit was unclear. Over the past two decades, a strong case has been made that corrections to the dipole approximation are necessary for accurately …

Identify An Ideal Residential Wall Assembly For Las Vegas Climate Considering Construction Cost, Energy Performance And Embodied Energy, Johny Corona

UNLV Theses, Dissertations, Professional Papers, and Capstones

Global warming and climate change has drawn great concerns in recent years due to the impact residential buildings have on the environment. Heating and cooling consumption make up most of household energy in the desert southwest. This energy demand is a big contributor of carbon emissions being release on to the environment. In an effort to minimize energy consumption, this research study aims to identify an energy efficient wall assembly that can be use in the U.S. desert southwest, that is suitable for the environment. With the use of research and simulations, using BEopt version 2.4.0.1, this investigation compares and …

Empirical Study Of Concurrent Programming Paradigms, Patrick M. Daleiden

UNLV Theses, Dissertations, Professional Papers, and Capstones

Various concurrent programming paradigms have been proposed by language designers in an effort to simplify some of the unique constructs required to handle concurrent programming tasks. Despite these different approaches, however, there has been no general clear winner accepted by software developers and different paradigms are regarded to have strengths and weaknesses in certain areas. This thesis was motivated by the desire to investigate the question of whether or not there are measurable differences between two widely differing paradigms for concurrent programming: Threads vs. Communicating Sequential Processes. The mechanism for observing and comparing these paradigms was a randomized controlled trial …

Security Threats From Uas And Its Mitigation Through Detection And Tracking, Sai Ram Ganti

UNLV Theses, Dissertations, Professional Papers, and Capstones

Unmanned Aerial Systems (UAS) are being used commonly for surveillance, providing valuable video data and reducing risk for humans wherever applicable. The cost of small UAS can range from as low as $30 to high as $5000, which makes it affordable by everyone. Most of the UAS are equipped with a camera which results in activities like disruption of privacy or capturing sensitive data. This research is aimed at developing a system which can detect and identify a drone and apply some counter measures to stop its functions or make it go away. The air traffic will increase significantly in …

Differences In Perceived Importance Of Preventative Services And Healthcare Provider Trust Among Hispanics, Jonathan James Gore

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Hispanic population varies greatly in their risk factors, health outcomes and access to care by country of origin, level of education and language dominance (Vega & Amaro, 1994) (Fiscella, Franks, Doescher, & Saver, 2002b). The differences within the Hispanic population also extend to their knowledge and attitudes toward health choices and maintenance, where they receive their health information, and what they access to meet their health care needs. Subpopulations within the Hispanic community as defined by language dominance and nativity must be understood as separate and distinct so that the health needs of each can be adequately addressed. The …

A Simulator Application For Distributed Leader Election Algorithms, Sugeeswara Gurudeniya

UNLV Theses, Dissertations, Professional Papers, and Capstones

We present an application program, Distributed Algorithm Simulator, to simulate the execution of distributed leader election algorithms in a ring-network. The application was developed using Visual C# on Microsoft .NET Framework 4.5. The Distributed Algorithm Simulator consists of two major components: A Visual Simulator, which visually demonstrates the execution of the algorithms; and a Textual Simulator, which simulates the execution in text format. In both cases the end-result can be saved to a file.

The Visual Simulator displays the network in a ring orientation with circles representing the nodes, and numbers on them showing the node IDs. The user has …

Top-K Nodes Identification In Big Networks Based On Topology And Activity Analysis, Sweta Gurung

UNLV Theses, Dissertations, Professional Papers, and Capstones

Graphs and Networks have been the most researched topics with applications ranging from theoretical to practical fields, such as social media, genetics, and education. In many competitive environments, the most productive activities may be interacting with high-profile people, reading a much-cited article, or researching a wide range of fields such as the study on highly connected proteins. This thesis proposes two methods to deal with top-K nodes identification: centrality-based and activity-based methods for identifying top-K nodes. The first method is based on the topological structure of the network and uses the centrality measure called Katz Centrality; a path based ranking …

Ab Initio Structure Determination And Property Characterization Of High-Pressure Ca-O Compounds And Li2(Oh)Br Crystals, Christopher Higgins

UNLV Theses, Dissertations, Professional Papers, and Capstones

Theoretical modeling and computational simulations play an important role in materials research. In this thesis, we report on the study of two material systems using various computational methods. The first material system studied here are Cax-Oy compounds under high pressure. Calcium and oxygen are amongst the most abundant elements on Earth, and they form the compound calcium oxide (CaO) that is widely used and very stable at ambient pressures. Although the crystal structure and chemical composition of CaO seems to be simple and well understood, metastable or stable Ca-O compounds with unconventional stoichiometry may exist at high pressures. In this …

Algorithms For Monotone Paths With Visibility Properties, Bikash Lama Bamjan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Constructing collision-free paths in Euclidean space is a well-known problem in computational geometry having applications in many fields that include robotics, VLSI, and covert surveillance. In this thesis, we investigate the development of efficient algorithms for constructing a collision-free path that satisfies directional and visibility constraints. We present algorithms for constructing monotone collision-free paths that tend to maximize the visibility of the boundary of obstacles. We also present implementation of some monotone path planning algorithms in Java Programming Language.

Creating A Dynamic, Multi-Purpose Correction For Multiple Geometries And Field Sizes To Account For Off-Axis And Asymmetric Backscatter With Varian Portal Dosimetry, Remy Manigold

UNLV Theses, Dissertations, Professional Papers, and Capstones

Intensity modulated radiation therapy and volumetric modulated arc therapy are increasingly common in radiation therapy due to their benefits of target conformity and normal tissue sparing. Due to the complexities of plan delivery and the precision required, the dose delivered must be accurately measured for quality assurance (QA). One of the most efficient ways to perform patient-specific QA when using clinical linear accelerators (linac) is to use an electronic portal imaging device (EPID). Amorphous silicon (aSi) Electronic Portal Imaging Devices (EPIDs) are attached to the linac and can provide real-time feedback with spatial resolution on the order of sub-millimeter pixel …

Analysis Of Power-Down Systems With Five States, Govind Pathak

UNLV Theses, Dissertations, Professional Papers, and Capstones

We consider a device, which has states ON, OFF and fixed number of intermediate states.In the ON state the device uses full power whereas in the OFF state the device consumes no energy but a constant cost is associated with switching back to ON. Intermediate states use some fraction of energy proportional to the usage time but switching back to the ON state has a constant setup cost depending on the current state. Such systems are widely used to conserve energy, for example to speed scale CPUs, to control data centers, or to manage renewable energy.

We analyze such a …

A Web-Based Solution For Small Unmanned Aircraft System (Suas) Traffic Management, Monetta Angelique Shaw

UNLV Theses, Dissertations, Professional Papers, and Capstones

There is currently no system in place for safely managing small unmanned aircraft systems (UAS). Small UAS (sUAS) pose a safety hazard to both manned aircraft and people on the ground. The initial solution to this problem proposed in this paper is a system that consists of a web server and an Android mobile application (app). In this solution, the server is only accessible through the Android mobile app. After evaluating the initial solution, we determine that the system in this solution would be unable to quickly adjust to changes in technology and in the sUAS industry. To solve this …

An Arithmetic-Based Deterministic Centroid Initialization Method For The K-Means Clustering Algorithm, Matthew Michael Mayo

Theses and Dissertations

One of the greatest challenges in k-means clustering is positioning the initial cluster centers, or centroids, as close to optimal as possible, and doing so in an amount of time deemed reasonable. Traditional fc-means utilizes a randomization process for initializing these centroids, and poor initialization can lead to increased numbers of required clustering iterations to reach convergence, and a greater overall runtime. This research proposes a simple, arithmetic-based deterministic centroid initialization method which is much faster than randomized initialization. Preliminary experiments suggest that this collection of methods, referred to herein as the sharding centroid initialization algorithm family, often outperforms random …

An Exploration Of Rule Clustering In Cellular Automata Rule Spaces, Jordon Huffman

Theses and Dissertations

The study of complex systems examines the global behavior of a system and how the individual parts of the system affect that behavior [1]. The study of complex systems spans across many fields of science like biology, physics, engineering, and computer science. One area of complex systems that has not been fully explored is cellular automata. Since its discovery by John von Neumann, there have been no consistent ways of categorizing similarities between cellular automata rules or collecting similar rules for observation. This thesis introduces an approach to identifying clusters of similar rules and extracting rules from that cluster. Several …

Geological Conditions Required For The Fluvial Erosion Of Titan’S Impact Craters, Rebeca M. Kinser

Theses and Dissertations

In comparison to other icy satellites, Titan has a small number of impact craters on its surface. Its dense atmosphere screens smaller impactors from the surface, but this alone does not account for the lack of impact craters, especially at large diameters. This suggests that Titan has a relatively young surface and/or erosional processes have effectively removed craters from its surface. For example, fluvial erosion could degrade craters such that they would be unrecognizable from an orbiting spacecraft such as Cassini. The amount of erosion, however, will depend on a number of factors including the geological and meteorological conditions of …