Physical Sciences and Mathematics Commons^™

Fundamental Studies On Ultrafast Separations And Development Of Geopolymer Based Base-Stable Stationary Phase Media, Rasangi Madhumali Wimalasinghe K.K.D.G.

Chemistry & Biochemistry Dissertations

This thesis consists of two sections. In the first section fundamentals of ultrafast separations is discussed. Ultrafast chromatography is an emerging area of separation science due to its applicability in high-throughput separations and purifications. State of the art superficially porous particles packed short and ultrashort columns are utilized to obtain the amenable speed and chromatographic efficiency required in ultrafast chromatography. Modifications to state of the art HPLC and UHPLC instrumentation required in cases where ultrafast separations are needed. Sub-second liquid chromatographic separations and ultrafast separations of biomolecules and complex mixtures are demonstrated. Fundamentals behind the analytical chromatographic column packing are …

The Response Of Ionosphere And Thermosphere To The High Latitude Energy Deposition, Yang Lu

Physics Dissertations

The ionosphere and thermosphere are the important regions in the Earth upper atmosphere. They represent the ionized and neutral particles, respectively. The main external energy sources in those regions are solar radiation and geomagnetic energy due to the solar wind-magnetosphere interaction. The neutral particles are ionized by solar radiation on the dayside. Meanwhile, the energy deposition from the magnetosphere is also critical at high latitudes. The energy source at high latitudes depends on whether the local magnetic field line is closed or not. In the polar cap region where it is connected to open magnetic field line, the main energy …

Impacts Of Habitat Attributes And Community Gardens On Urban Bird Communities, Samuel Glenn Ortiz

Theses and Dissertations

The Rio Grande Valley of Southern Texas is a major agricultural region yet has some of the highest hunger rates in the USA. Urbanization and agriculture affect biodiversity, which is well studied, but little is known about how agriculture affects biodiversity in urban areas. We investigated how different urban attributes, including those related to urban farming, impact bird communities in Brownsville and Harlingen, TX, and compared sites that have community gardens to those that do not. To study three key urban habitat characteristics, we identified sites that exhibited all possible combinations of these factors, quantified land cover classes related to …

Photocatalytic Degradation Of Simazine Using Zno/Go Composites, Kenneth Ray Flores

Theses and Dissertations

The photocatalytic degradation of simazine (SIM) by Zinc oxide/graphene oxide (ZnO/GO) composites, under visible light irradiation, was investigated to determine various reaction parameters, of initial pH, ZnO loading on GO, and catalyst mass. A pH of 2 was determined to be the optimal reaction pH for all ZnO/GO catalysts. A loading mass of 40mg for the 20 & 30mmol composites; whereas a 10mg mass was determined to be most effective for the 10mmol composite. The reaction followed second order kinetics for the degradation process, the reaction dependence was determined to be on the concentration of SIM in solution. All ZnO/GO …

Three Dimensional Carbon Nanotube Yarn Based Perovskite Solar Cells, Istiak Hussain

Theses and Dissertations

Perovskite solar cells (PSC) have emerged as a promising photovoltaic technology in lab scale with a short time of research due to their high power conversion efficiency, simple device fabrication, all solid-state structure and the possibility to ingrate the traditional device into fiber format. In this work, a three-dimensional (3D) perovskite solar cell is demonstrated using functionalized carbon nanotube yarn (CNT) as both cathode and anode. TiO2 and 2,2,7,-7-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD) are used as the electron transporting and hole transporting material respectively. The TiO2 oxide layer is deposited on the top of the twisted carbon nanotube yarn and annealed with TiCl4 …

Green Synthesis/Biosynthesis Of Silver Nanoparticles By Using Orange Peel Extract, Leela Joshi

Theses and Dissertations

Joshi, Leela, Green Synthesis/Biosynthesis of Silver Nanoparticles by Using Orange Peel Extract. Master of Science (MS), December, 2018, 40 pages, 23 figures, references, 36 titles. In this work, we report synthesis of silver nanoparticles (AgNPs) with an average size of ~6 nm. The aqueous solution of Ag+ ions is reduced using an aqueous extract from orange peel (Citrus Sinensis) at varying pHs. Reduction of Ag+ ions in solution was monitored using UV-visible absorption spectroscopy, and the corresponding surface plasmon resonance of AgNPs at 435 nm. The solution changed color from yellow to reddish-brown upon bioreduction of silver nitrate in orange …

Studying Mechanical And Structural Properties Of Β-Lg And Β-Cn Fibrils Using Atomic Force Microscopy, Hugo A. Villar

Theses and Dissertations

Amyloid fibrils from milk proteins have recently been the subject of extensive investigations in biophysics. The purpose of this thesis is to investigate the dynamics of fibrillation and the mechanical properties of β-LG and β-CN fibers using AFM-Quantitative Nanomechanical Mapping (QNM) and AFM-force spectroscopy. β-LG required one day of heating at 80 °C , pH 2 to fibrillate in solution; β-CN required three days. Using the AFM-QNM mode an average elastic modulus of 4.3 GPa was determined for the β-LG fibers and 3.1 GPa for β-casein fibers. A persistence length of 920 nm was determined using end to end distance …

Effects On Altering Reaction Conditions In Suzuki Cross Coupling Reactions Using The Microwave, Javier Alejandro Perez

Theses and Dissertations

Over the last few decades, Suzuki coupling has become a common process for the synthesis of intermediates in pharmaceutical and industrial applications. It is well known that palladium is an effective catalyst for the formation of cross-coupled products. Therefore, this catalyst was tested in a series of reactions. Also, it is believed that other catalyst with similar properties to palladium can work, for example cerium. Therefore, a cerium hydroxide catalyst was synthesized in lab and used as a potential catalyst for the Suzuki reaction. For this study, some bases were investigated (NaOH, Na2CO 3, K3PO4, NaNO3, NaHCO3, etc) for the …

Generalized &Thetas;-Parameter Peakon Solutions For A Cubic Camassa-Holm Model, Michael Rippe

Theses and Dissertations

In this paper we outline a method for obtaining generalized peakon solutions for a cubic Camassa-Holm model originally introduced by Fokas (1995) and recently shown to have a Lax pair representation and bi-Hamiltonian structure by Qiao et al (2012). By considering an amended signum function—denoted sgn &thetas;(x)—where sgn(0) = &thetas; for a constant &thetas;, we explore new generalized peakon solutions for this model. In this context, all previous peakon solutions are of the case &thetas; = 0. Further, we aim to analyze the algebraic quadratic equation resulting from a substitution of the single-peakon ansatz equipped with our amended …

The Mathematical Aspects Of Theoretical Physics, Hassan Kesserwani

Theses and Dissertations

The aim of this thesis is to outline the mathematical machinery of general relativity, quantum gravity, cosmology and an introduction to string theory under one body of work. We will flesh out tensor algebra and the formalism of differential geometry. After deriving the Einstein field equation, we will outline its traditional applications. We then linearize the field equation by a perturbation method and describe the mathematics of gravitational waves and their spherical harmonic analysis. We then transition into the derivation of the Schwarzschild metric and the Kruskal coordinate transformation, in order to set the stage for quantum gravity. This sets …

Longitudinal And Temporal Comparison Of Beach Sand On The Rio Grande Delta System, Samantha B. Moore

Theses and Dissertations

The Rio Grande is the 5th longest river in North America and defines a significant extent of the United States-Mexico border. It extends for 2830 km from its headwaters in the Rocky Mountains of Colorado to the Gulf of Mexico. The Rio Grande is fed by streams from the Sangre de Cristo Mountains, the Rio Conchos, the Pecos River, runoff from the Sacramento Mountains area, Devils River, the Rio Salado, and the Rio San Juan. This study addresses how the composition of sand forming the Rio Grande river delta into the Gulf of Mexico at Boca Chica Beach is changed …

Similarity Of Introduced Plant Species To Native Ones Facilitates Naturalization, But Differences Enhance Invasion Success, Jan Divíšek, Milan Chytrý, Brian Beckage, Nicholas J. Gotelli, Zdeňka Lososová, Petr Pyšek, David M. Richardson, Jane Molofsky

College of Arts and Sciences Faculty Publications

The search for traits associated with plant invasiveness has yielded contradictory results, in part because most previous studies have failed to recognize that different traits are important at different stages along the introduction–naturalization–invasion continuum. Here we show that across six different habitat types in temperate Central Europe, naturalized non-invasive species are functionally similar to native species occurring in the same habitat type, but invasive species are different as they occupy the edge of the plant functional trait space represented in each habitat. This pattern was driven mainly by the greater average height of invasive species. These results suggest that the …

An Examination Of What Motivates Utah Residents To Adopt The Practice Of Rainwater Harvesting, D. Wayne Honaker

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Although most of the earth is covered in water, a very limited amount of that water is fresh water, which is essential to our survival. Therefore, it is imperative that we do all that is possible to conserve and protect our extremely limited water resources, especially in arid regions such as the American West. While there are many ways and means to protecting and preserving our water resources, this thesis focuses on the strategy of rainwater harvesting (RWH) as it is done throughout the state of Utah. RWH is defined as taking the precipitation that falls on our built structures …

Running The Cañons Of The Rio Grande: Part 2 Boquillas Canyon, Texas And Coahuila, Todd L. Blythe

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In 1899, Robert T. Hill led the first scientific exploration of the remote segment of the Rio Grande known as the Big Bend. Hill’s observations from this expedition were published in an article titled “Running the Cañons of the Rio Grande.” At the time of Hill’s expedition, the stream flow of the Rio Grande was largely depleted by water development in the upstream portions of the basin. The continued overallocation of the Rio Grande has led to the degradation of aquatic ecosystems in the Big Bend, one of North America’s largest transboundary protected areas, such that management of natural resources …

Multi-Resolution Analysis Using Wavelet Basis Conditioned On Homogenization, Abibat Adebisi Lasisi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This dissertation considers an approximation strategy using a wavelet reconstruction scheme for solving elliptic problems. The foci of the work are on (1) the approximate solution of differential equations using multiresolution analysis based on wavelet transforms and (2) the homogenization process for solving one and two-dimensional problems, to understand the solutions of second order elliptic problems. We employed homogenization to compute the average formula for permeability in a porous medium. The structure of the associated multiresolution analysis allows for the reconstruction of the approximate solution of the primary variable in the elliptic equation. Using a one-dimensional wavelet reconstruction algorithm proposed …

New Ca-Id-Tims Detrital Zircon Constraints On Middle Neoproterozoic Sedimentary Successions, Southwestern United States, Abigail R. Bullard

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Three related sedimentary successions located in Arizona, Utah, and California were deposited in basins on proto-North America during the early rifting of Rodinia (~780 Mya). Previous detrital zircon U-Pb maximum ages for the units are inexact, making it difficult to piece together what happened at this point in Earth history.

We report better maximum age constraints on these units obtained by subjecting detrital zircons to high-precision CA-ID-TIMS analysis, which provide more exact ²⁰⁶Pb/²³⁸U ages. These new data significantly improve the precision for the base of the ChUMP units, with an average age of 775.63 ± 0.27 Ma …

Improving Accuracy Of The Edgebox Approach, Kamna Yadav

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Object region detection plays a vital role in many domains ranging from self-driving cars to lane detection, which heavily involves the task of object detection. Improving the performance of object region detection approaches is of great importance and therefore is an active ongoing research in Computer Vision. Traditional sliding window paradigm has been widely used to identify hundreds of thousands of windows (covering different scales, angles, and aspect ratios for objects) before the classification step. However, it is not only computationally expensive but also produces relatively low accuracy in terms of the classifier output by providing many negative samples. Object …

Climate Change Perceptions And Adaptation Among Small-Scale Farmers In Uganda: A Community-Based Participatory Approach, Thomas Derr

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Climate change in the East African country of Uganda is causing severe variations in the once predictable seasonal weather patterns that farmers had come to depend on. This, in combination with social and economic challenges, has significantly increased the vulnerability of farmers who make up the majority of Uganda’s population. Previous knowledge and observations suggest that Ugandan farmers may be reluctant or slow to change their practices in response to the changing climate. Strategies are therefore needed to identify challenges and sustainable solutions. This research used qualitative data collection methods known as participatory rural appraisal (PRA) and participatory action research …

Historical Channel Change Caused By A Century Of Flow Alteration On Sixth Water Creek And Diamond Fork River, Ut, Jabari C. Jones

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Changes in the amount of water and sediment that enter a river can change its shape and size. The way that rivers change is affected by a variety of factors, including the size of the sediment in the river, and past changes to the river. The Diamond Fork River in central Utah has been altered by water delivered from the Colorado River system for over a century. Beginning in 1915, water used for irrigation was delivered through a tributary, Sixth Water Creek, with daily summer flows that were much larger than natural flows. This caused drastic change to the rivers, …

Sensitivity Of The Opal Instrument For Gravity Wave Detection, Kenneth I. Zia

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Knowing what goes on in the upper atmosphere (∼80-140 km) is very important to the space science community. There are several competing forces that influence the temperature and densities of neutral molecules in that region. OPAL (Optical Profiling of the Atmospheric Limb) is funded by the National Science Foundation (NSF) to measure the temperature there using light from oxygen molecules (∼760 nm). To accomplish this,OPAL is built into a CubeSat (a satellite the size of a loaf of bread) to be launched from the International Space Station (ISS) at an altitude of about 400 km. This vantage point is needed …

The Development Of Hydrodynamic And Kinetic Models For The Plasmasphere Refilling Problem Following A Geomagnetic Storm, Kausik Chatterjee

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The objective of this dissertation is the development of computer simulation-based models for the modeling of upper ionosphere, starting from the first principles. The models were validated by exact analytical benchmarks and are seen to be consistent with experimentally obtained results. This area of research has significant implications in the area of global communication. In addition, these models would lead to a better understanding of the physical processes taking place in the upper ionosphere.

Comparing Performance Of Gene Set Test Methods Using Biologically Relevant Simulated Data, Richard M. Lambert

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Today we know that there are many genetically driven diseases and health conditions. These problems often manifest only when a set of genes are either active or inactive. Recent technology allows us to measure the activity level of genes in cells, which we call gene expression. It is of great interest to society to be able to statistically compare the gene expression of a large number of genes between two or more groups. For example, we may want to compare the gene expression of a group of cancer patients with a group of non-cancer patients to better understand the genetic …

“I Really Don’T Look For Certifications, It All Has To Do With Personal Relationships”: The Construction Of A Meat Philosophy And Innovation Adoption By Culinary Professionals In The Rocky Mountain Region, Kailie B. Leggett

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Demand for new methods of beef production is rising due to concern over potential impacts on human health, animal welfare, and the environment. Researchers at Utah State University have developed a method of beef production from cattle finished on tannin-containing legume forages in the Rocky Mountain Region in order to address those concerns. To ensure success of this product, the demand and marketability needed to be assessed. Food values addressed through new production standards and certifications are communicated through labeling by culinary professionals in the kitchen and behind service counters. This research study utilized qualitative methods to understand how culinary …

Examining Teacher Perceptions When Utilizing Volunteers In School-Based Agricultural Education Programs, Ashley B. Cromer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

There has been little research conducted related to how school-based agricultural (SBAE) teachers perceive the utilization of volunteers in the classroom. The United States is facing a shortage of SBAE teachers, and with turnover rates that are not sustainable, solutions for support and reduction of the SBAE teachers’ workload must be sought with diligence. There is potential for volunteers to reduce some of the responsibilities that the SBAE teacher is faced with. The purposes of this study are to determine the demographic characteristics of the volunteers being utilized and of the SBAE teachers, determine the perceived benefits, barriers and beliefs …

The Power Law Distribution Of Agricultural Land Size, Lauren Chamberlain

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This paper demonstrates that the distribution of county level agricultural land size in the United States is best described by a power-law distribution, a distribution that displays extremely heavy tails. This indicates that the majority of farmland exists in the upper tail. Our analysis indicates that the top 5% of agricultural counties account for about 25% of agricultural land between 1997-2012. The power-law distribution of farm size has important implications for the design of more efficient regional and national agricultural policies as counties close to the mean account for little of the cumulative distribution of total agricultural land. This has …

Surviving A Civil War: Expanding The Scope Of Survival Analysis In Political Science, Andrew B. Whetten

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Survival Analysis in the context of Political Science is frequently used to study the duration of agreements, political party influence, wars, senator term lengths, etc. This paper surveys a collection of methods implemented on a modified version of the Power-Sharing Event Dataset (which documents civil war peace agreement durations in the Post-Cold War era) in order to identify the research questions that are optimally addressed by each method. A primary comparison will be made between a Cox Proportional Hazards Model using some advanced capabilities in the glmnet package, a Survival Random Forest Model, and a Survival SVM. En route to …

Different Estimation Methods For The Basic Independent Component Analysis Model, Zhenyi An

Arts & Sciences Electronic Theses and Dissertations

Inspired by classic cocktail-party problem, the basic Independent Component Analysis (ICA) model is created. What differs Independent Component Analysis (ICA) from other kinds of analysis is the intrinsic non-Gaussian assumption of the data. Several approaches are proposed based on maximizing the non-Gaussianity of the data, which is measured by kurtosis, mutual information, and others. With each estimation, we need to optimize the functions of expectations of non-quadratic functions since it can help us to access the higher-order statistics of non-Gaussian part of the data. In this thesis, our goal is to review the one of the most efficient estimation methods, …

The Role Of Information Communication Technologies (Icts) In Shaping Identity Threats And Responses, Mary Macharia

Graduate Theses and Dissertations

With the rising use of social media, people are increasingly experiencing, and responding to, identity threats online. This sometimes leads to online backlash via “cybermobs” or the creation of online social movements that traverse offline. Prior information systems (IS) research on identity threats and responses largely focuses on information communication technology (ICT) implementations within organizations in an offline context. Therefore, we lack understanding of ICT-mediated identity threats and responses and ways to promote healthier and productive interactions online. This two-essay dissertation seeks to fill this gap. Essay 1 combines a review of ICT-mediated identity threats with a qualitative study (based …

Synthesis Of Dicamba Glucosides For The Study Of Environmental Dicamba Drift Effects On Soybeans, Holly Wallace

Graduate Theses and Dissertations

The most popular herbicide used for weed control has been glyphosate for many years in the Midwestern United States. Plants have begun to develop a resistance to glyphosate due to over use of the herbicide. This herbicide resistance has pushed farmers to turn to alternative herbicides such as dicamba and 2,4-D. Recently agrochemical companies have developed genetically modified crops that are resistant to herbicides such as dicamba. These modified crops allow farmers to spray their fields with dicamba without fear of crop damage. Farmers of non-genetically modified crops, however, suffer damage and loss of yield from herbicide drift effects of …

Sequential Inference For Hidden Markov Models, Michael Ellis

Graduate Theses and Dissertations

In many applications data are collected sequentially in time with very short time intervals between observations. If one is interested in using new observations as they arrive in time then non-sequential Bayesian inference methods, such as Markov Chain Monte Carlo (MCMC) sampling, can be too slow. Increasingly, state space models are being used to model nonlinear and non-Gaussian systems. The structure of state space models allows for sequential Bayesian inference so that an approximation to the posterior distribution of interest can be updated as new observations arrive. In special cases, the exact posterior distribution can be updated through conjugate Bayesian …