Physical Sciences and Mathematics Commons^™

Experimental Exploration Of Shared Magnetic Phases Between Diverse Systems Of Iron-Pnictide Superconductors, Ryan Scott Stadel

Graduate Research Theses & Dissertations

The exciting field of iron-pnictide superconductors offers unique opportunities for studying the relationship between magnetism and unconventional superconductivity. This is vital to developing an understanding of the microscopic origin of high-temperature superconductivity, which is itself an important step in harnessing such a potentially revolutionary technology.

Polycrystalline and crystalline samples are synthesized over a diverse collection of related iron-pnictide systems including (Ca,Sr,Ba)1-xNaxFe2As2, Ba(Fe1-xCox)2As2 (122s), and LaFeAs1-xPxO, and TbFeAs1-xPxO (1111s). These compounds are characterized through various types of neutron and x-ray diffraction on multiple instruments, as well as muon spin resonance, and magnetic susceptibility measurements.

A thorough investigation into the conditions under …

Collisional Methods With Applications To Charged Particle Beams, Afnan Al Marzouk

Graduate Research Theses & Dissertations

Accurate and efficient computational methods are essential to study the dynamics of charged particle beams. Most of the available numerical methods in beam physics are based on the collisionless model which is sufficient for applications that does not depend on Coulomb collisions of the simultaneously interacting particles. However, the development of collisional numerical methods has become greatly important in recent years for applications where collisions play an important role such as the electron cooling of high energy hadron beams. While collisional methods can provide very accurate simulations, their algorithms are very complex, and they face efficiency challenges. In this work, …

Electrochemical Study Of The Performance Of Manganese Vanadium Oxide Cathodes In Zinc Batteries, Sarat Alabidun

Graduate Research Theses & Dissertations

Zinc metal batteries are considered a promising alternative for grid energy storage due to the low redox potential (-0.76V vs SHE) and high theoretical specific capacity (850mAh/g) of zinc metal anode as well as its compatibility with aqueous electrolytes. They however face issues of poor cathode stability and rapid capacity fading. Several methods have been devised to improve the stability of the cathode materials and develop novel cathode materials with better performance including the metal ion doping of intercalation materials.This study investigated the performance of zinc metal batteries with novel manganese vanadium oxide cathodes. Organic structure directing agents have been …

Investigation Of Spontaneously Patterned Nanoporous Organosilicate Thin Film Channels For Liquid Chromatography Applications., Ashwin Sanjay Bhaskaran

Graduate Research Theses & Dissertations

Microscale devices are attractive options for the advancement of biomedical engineering and life science. They have huge potential in the pharmaceutical and biomedical fields provided the critical factors such as device size, product purity and efficiency are not a hindrance. In most cases, traditional microelectronics fabrication processes are quite costly and complicated. By improving on them, their application in fields such as chemical sensing, detection and analysis is possible. By implementing this on a chip, we can reduce the cost and improve portability. This thesis focuses on the investigation of a novel class of spontaneously patterned nanoporous organosilicate nanoparticle-based films …

Seismic Imaging Of The Lithospheric Structure Beneath The Upper Midwestern United States, Anthony Guajardo

Graduate Research Theses & Dissertations

The upper midwestern United States is located within the North American Craton. This area has not undergone major deformation and metamorphism since the latest rifting events in the late Precambrian to early Cambrian (0.55 to 0.53 Ga). However, this area is not completely absent of seismicity, and major structural geologic features are present, including the Wisconsin Arch, LaSalle Deformation Belt, northern part of the Illinois basin and, deeper, the presumed transition between the Yavapai and Mazatzal tectonic provinces. Since the late 1800s, approximately 30 felt earthquakes of magnitude 2 or greater have occurred within the study area. It is likely …

Fly On The Wall: Comparing Arthropod Communities Between Islands With And Without House Mice (Mus Musculus), Wieteke A. Holthuijzen

Graduate Research Theses & Dissertations

Invertebrates are key to island ecosystems but impacts from invasive mammalian predators are not well documented or understood. Given this knowledge gap, we studied terrestrial arthropod communities in the presence of a common invasive rodent (house mice, Mus musculus) on a subtropical atoll—Midway Atoll National Wildlife Refuge (MANWR). Here, invasive mice recently began to attack and depredate nesting seabirds, prompting a mouse eradication. Although eradication planning efforts are underway, uncertainty remains regarding the ecosystem’s response to mouse removal. As part of a pre-eradication investigation, we conducted a baseline survey of MANWR’s arthropod community structure and diversity, comparing islands with and …

Geometric Properties Of Representation Varieties For An Elementary Abelian Group Of Rank 2 In Positive Characteristic, Eric Johnson

Graduate Research Theses & Dissertations

This dissertation’s motivation is the exploration of the irreducible components of Repn(kG), the affine variety whose points are n-dimensional representations of a finite group G over a field k. We let G = Z/pZ×Z/pZ and assume k is algebraically closed with char(k) = p > 0. In this case there is an isomorphism of affine varieties φ : Repn (kG) → C nil 1 (n) where C nil 1 (n) = {(x, y) Mn(k)×Mn(k) | x p = y p = xy−yx = 0}. Hence, for an irreducible component X of Repn (kG), φ(X) is an irreducible component of C nil …

A Time Series Analysis Approach To Forecasting Covid-19 Cases And Deaths: An Analysis Of Covid-19 Data In Colombia, Andrea Jackson-Sagredo

Graduate Research Theses & Dissertations

The novel Coronavirus, known as COVID-19 is a highly contagious and transmissible infectious disease that has taken a toll throughout the entire world for over a year. The inner workings and long term effects of COVID-19 continue to be misunderstood. While COVID-19 has impacted all countries tremendously, Latin American countries and specifically Colombia have been impacted significantly by the virus. This thesis investigates the potential to forecast COVID-19 cases and deaths using Time Series Analysis methods and models for the South American country of Colombia. Time series analysis on Colombian COVID-19 data begins with data processing on a data set …

Optimization Of Dynamic Objective Functions Using Path Integrals, Paramahansa Pramanik

Graduate Research Theses & Dissertations

Path integrals are used to find an optimal strategy for a firm under a Walrasian system. We define dynamic optimal strategies and develop an integration method to capture all non-additive non-convex strategies. We also show that the method can solve the non-linear case, for example Merton-Garman-Hamiltonian system, which the traditional Pontryagin maximum principle cannot solve in closed form. Furthermore, we assume that the strategy space and time are inseparable with respect to a contract. Under this assumption we show that the strategy spacetime is a dynamic curved Liouville-like 2-brane quantum gravity surface under asymmetric information and that traditional Euclidean geometry …

Weather-Related Carbon Monoxide Poisoning In The United States: 2000-2019, Bailey Raine Stevens

Graduate Research Theses & Dissertations

Carbon monoxide (CO) is a colorless, odorless gas that can cause injury or death if inhaled. CO is a frequent secondary hazard induced by the aftereffects of natural hazards as individuals, families, and communities will often seek alternative power sources for heating, cooking, lighting, and cleanup during the emergency and recovery phases of a disaster. These alternative power sources – such as generators, petrol heaters, and vehicles, exhaust CO – can ultimately build to toxic levels in enclosed areas. Ever-increasing environmental and societal changes combined with an aging infrastructure are increasing the odds of power failures during hazardous weather events, …

Stochastic Infection In Network Models With Applications To Pollution Analysis, Alexander Thor Wold

Graduate Research Theses & Dissertations

The continued adoption and escalation of commercial surface extraction techniques threatens to contaminate adjacent river networks across the coal mining landscape. We look to simulate the movement of this pollution across connected graph structures using stochastic block model methodologies, fueled from work and theory derived from exponential random graph models. We begin our study by applying our virtual experiment to the motivating material, later offering an exhaustive walk through of the simulation itself. Afterwards, we present our findings and their implications to water pollution analysis, emphasizing a need for this research and expanding on some inferential statistics left for later …

Experimental And Numerical Investigation Of Instabilities In A Two-Mirror Fabry-Perot Resonator, Matthew J. Urfer

Graduate Research Theses & Dissertations

Fabry-Perot cavities have a variety of applications in science and industry. Maintaining the stability of a Fabry-Perot cavity is paramount. A Fabry-Perot cavity requires such precision that, if the injected laser pulse is slightly misaligned or the eigenmodes of the cavity are slightly mismatched, the cavity will destabilize from the fundamental mode and begin to exhibit high order modal structure. Depending on their nature, small misalignments will couple to the first order Gaussian modes. This paper discusses the effects of these small misalignments, observed mode structures, as well as computational results from simulations of the optical system.

Beam Phase Space Diagnostic Techniques Along The Fermilab Muon Campus Extraction Line, Benjamin Simons

Graduate Research Theses & Dissertations

The pursuit of physics beyond the Standard Model relies on the ability to make highly sensitive measurements with a high level of precision. Particle accelerators have been a cornerstone for the foundation of tools that have allowed us to continue to probe the limits of what the Standard Model can predict.

This thesis is focused on applying various measurement techniques, some standard and one not so standard, that provide crucial information about beam optics and beam quality for the purposes of monitoring the beam as it is guided throughout a beam transport system. After the measuring techniques have been described, …

Some Special Cases Of The Andrews-Bowman Continued Fraction, Bryan Thomas Zollinger

Graduate Research Theses & Dissertations

One of the most famous results from q-series is that of the Rogers-Ramanujan continued fraction, given by [special characters omitted]. G.E. Andrews and D. Bowman gave a full extension of this continued fraction using G.N. Watson’s nonterminating very well-poised 8φ7 function. As opposed to Ramanujan’s generalization that only used four variables, this generalization is given in seven variables, and certain q-series identities naturally arise from it. As a special case of their theorem, Andrews and Bowman gave the following identity: [special characters omitted]. This thesis will give a full proof of Andrews and Bowman’s result, as well as investigate other …

Superconducting Cuprates: Synthesis, Characterization And Diffuse Scattering Properties, Bisham Poudel

Graduate Research Theses & Dissertations

Since its discovery more than a century ago, the fascinating phenomenon of superconductivity remains as mysterious as ever with the greatest challenge facing the condensed matter community being the elusive understanding of the microscopic origin leading to its inception. Many outstanding questions remain of which the role played by nematic fluctuations and structural disorder for the stabilization of superconductivity is not well understood. In this respect, superconducting YBa2Cu3O6+x (YBCO)-type cuprates present an ideal framework in which charge doping, structural disorder and various site manipulations can be explored in efforts to address some of these questions. Extensive synthesis and characterization efforts …

Diversity And Taxonomy Of Malagasy Pygmy Hippopotamuses, Allison Shackelton

Graduate Research Theses & Dissertations

Madagascar has many species of extinct megafauna, including up to three species of extinct hippopotamus. Subfossil hippo specimens have been found at sites across Madagascar, yet the number of species and taxonomic relationships of the extinct Malagasy pygmy hippopotamus are poorly understood. This thesis will analyze cranial and postcranial bones to improve our understanding of the diversity and taxonomy of Malagasy subfossil hippos, focusing on adults from Ampasambazimba and Tsaramody and juveniles from Ampasambazimba and Anjohibe. Measurements of the tibia and femur of adult specimens, which are used as diagnostic features in other studies, may not be accurate diagnostic features, …

Steepest Descent, Elastic Energy, And Stability In Infinite Dimensional Hilbert Manifolds, Scott W. Rexford

Graduate Research Theses & Dissertations

Consider constant-speed planar curves $\gamma =(x,y):[0,1]\to\mathbb{R}^2$ subject to $\gamma (0)=(0,0)$ and a prescribed value of $x(1)$, but with $y(1)$ unconstrained. We analyze the existence and the stability of critical curves of the elastic energy. Elastic curves are here thought of as points in an infinite-dimensional Sobolev manifold where the intrinsic gradient of the elastic energy vanishes. The admissible curves subject to constraints are members of a Riemannian submanifold using the ambient metric. A curve is stable with respect to the negative gradient flow if it is global or local minimum, and unstable otherwise. We analyze the stability of the classical …

Developing A Machine Learning Framework For Upwind Surveyed Regions, Witenberg Santiago Rodrigues Souza

Graduate Research Theses & Dissertations

Every year, the Oil & Gas industry loses $2B dollars due to fugitive natural gas leaks. Identifying the source of a leak is a complex challenge, especially in suburban areas where gas leakage may be mixed with other sources. Besides the multitude of possible locations for a leak in an urban area, surveying an entire city may take considerable time and funds depending on the chosen method. This work proposes a framework based on unmanned areal vehicles (UAV) to survey a region for gas leaks. To accomplish this goal, we rely on the concept of a Upwind Survey Region (USR). …

Clinical Applications And Feasibility Of Proton Ct And Proton Radiography, Christina Marie Sarosiek

Graduate Research Theses & Dissertations

Proton therapy is a form of radiation treatment for cancer that utilizes the Bragg peak to create conformal high dose regions around the tumor volume. However, the use of x-ray computed tomography (CT) and x-ray radiography for treatment planning and pre-treatment quality assurance procedures improves the achievable effectiveness of proton treatment plans (using proton CT) and the pretreatment verification (using proton radiography). Errors in the conversion from x-ray Hounsfield units (HU) to proton relative stopping powers (RSP) leads to errors in the predicted proton range. To account for the errors, 3.5% margins are included in the treatment plan. This means …

The Chemistry Of Superelectrophilic Phosphonium Ions, Nathan David Scanlon

Graduate Research Theses & Dissertations

A series of aryl-substituted phosphines have been prepared using superelectrophilic aromatic substitution chemistry. This chemistry involves reactive phosphonium-carbenium dications and related species. In addition to low molecular weight aryl-substituted phosphines, we also are able to prepare functionalized polystyrene products.

Investigation Of A Possible Cretaceous-Paleogene Boundary Layer In The Hell Creek Formation Near Ekalaka, Montana, U.S.A., Joshua Marvin Schwartz

Graduate Research Theses & Dissertations

The Hell Creek Formation is known for its abundant vertebrate fossils from the end of the Cretaceous. Its internal stratigraphy is poorly defined and it is therefore difficult to determine the precise stratigraphic location of a paleontological feature. This challenge could be overcome if a consistently appearing easily recognizable time horizon, such as the Chicxulub impact debris, or a well defined formational contact could be identified over a wide area of the Hell Creek Formation exposure, but these have been difficult to establish in some localities. The Carthage Institute of Paleontology (CIP) has collected Hell Creek specimens near Ekalaka, Montana …

A Glm Approach To Decomposing Wage Differential: Evidence From The Psid., Kassahun Mamo Geleta

Graduate Research Theses & Dissertations

The persistent gender wage differential, though declining through time, is the source of motivation to study the subject.A notable method to deal with the disparity is Oaxaca Blinder decomposition in combination with OLS estimation. This study follows a different approach that does not require the normality assumption and the log transformation of the wage variable. The study employs a generalized linear model (GLM) approach to estimate determinants of wage (measured in level) and combines the results with the Oaxaca Blinder decomposition method. The latter method quantifies the proportion of the wage gap which emanates from characteristics difference between men and …

Characterization Of Potential Anti-Infective Agents By Targeting Burkholderia Pseudomallei And Escherichia Coli Ispf, Dakota Lane Grote

Graduate Research Theses & Dissertations

With the likelihood of contracting an antibiotic resistant infection increasing, the need for novel anti-infective agents is critical. The development of novel anti-infective agents benefits from the identification of new target pathways necessary for the survival of the pathogen. One such target is the methylerythritol phosphate (MEP) pathway, responsible for the synthesis of the isoprenoid precursors isopentyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) in bacteria and other pathogenic organisms. The MEP pathway is an attractive target because it is specific to a wide range of pathogenic organisms, while humans have a separate pathway, the mevalonate (MVA) pathway, for the biosynthesis …

Miocene-Pleistocene Diatom Oxygen Isotope And Biogenic Silica Record From Iodp Site U1523, Ross Sea, Antarctica, Donald James Mclennan

Graduate Research Theses & Dissertations

The West Antarctic Ice Sheet (WAIS) plays a significant role in Earth’s climate. WAIS is currently retreating due to changes in wind-driven oceanic currents resulting in an increasing flux of warm waters to ice margins. Brine rejection in the Ross Sea is also major source of High Salinity Shelf water (HSSW) and Antarctica Bottom Waters (AABW), which creates a stratified ocean and plays a significant role in regulating Earth’s climate. Currently, there are very limited proxies that can quantify the variable input of HSSW formation on geologic time scales. Here we provide a 18Odiatom and biogenic silica (BSi) record which …

Gene-Based Disease Classification Using Bayesian Self-Organizing Map Neural Networks, Guangting Zhou

Graduate Research Theses & Dissertations

Genes perform vital roles in living beings. By taking charges of protein synthesis, genes are able to take control of the expression of living traits. There are a lot of diseases associated closely to our genes. By analyzing genetic information, we are able to detect or classify gene based diseases. Among genetic disease information technologies, microarray can be one of the widely used ones. Usually, microarray data records thousands of gene expression features from a small number of samples including both normal and abnormal expressed tissues. It provides standardized comparison information between normal and diseased tissues, so as to provide …

Frequentist Methods In Handling Misrepresentation Risk, Rexford Mawunyegah Akakpo

Graduate Research Theses & Dissertations

A commonly encountered risk in insurance business is misrepresentation risk. Misrepresentation is a type of insurance fraud where a policyholder or a policy applicant falsifies his or her risk status in order to pay cheaper premiums for more expensive future risks. It is difficult and expensive for insurance companies to detect this kind of risk. With high cost of sophisticated underwriting, it becomes a norm for insurance companies to regularly rely on the policy applicant to self-report most of their risk statuses. We employ a frequentist approach by using expectation-maximization (EM) algorithm to carry out maximum likelihood estimation of the …

Reversible Addition-Fragmentation Chain-Transfer Emulsion Polymerization And Its Application To Waterborne Coatings, Andrew Balgeman

Graduate Research Theses & Dissertations

Waterborne acrylic latex makes up a vast majority of the architectural coatings market, including most of the paints sold in retail stores. Most, if not all, of these latex formulations are prepared using radical polymerization of acrylic monomers. Reversible addition-fragmentation chain-transfer (RAFT) polymerization has been researched for over two decades, but to this point has made very little progress finding success in commercial applications. Indeed, a majority of RAFT research has been dedicated to successfully polymerizing different monomers with good degree of polymerization control, and very little research has been directed toward actual coating applications. In this study, we focused …

Trends In Observed And Simulated Radar Reflectivity For The 21st Century, Christopher Michael Battisto

Graduate Research Theses & Dissertations

The effects of climate change may influence the prevalence of regional atmospheric conditions supportive of hazardous convective weather (HCW). As a result, the possibility of an increase in the frequency, strength, and/or variability of thunderstorms and their high-impact hazards—including tornadoes, damaging winds, hail, and flash flood-producing downpours—has garnered much scientific and public interest. Radar reflectivity, which remotely assesses precipitation intensity, may be used to detect, track, catalog, and appraise HCW and their parent storms over broad spatiotemporal scales. Reflectivity may also be simulated with regional climate models, and recent, but limited, efforts using these simulation output have identified the potential …

Signal-Background Analysis For New Physics At Particle Colliders And The Criteria For Its Discovery, Prudhvi Nikhil Bhattiprolu

Graduate Research Theses & Dissertations

Although the Standard Model (SM) is now complete with the spectacular discovery of the Higgs boson at the Large Hadron Collider (LHC), there are many unsolved puzzles such as the electroweak hierarchy problem, dark matter, neutrino masses, etc., that need to be addressed. Theories proposed to solve these issues often involve new and exotic particles at the TeV scale and beyond. It is therefore of great importance to devise novel strategies to extract new physics signals with small rates lurking in huge backgrounds. My research detailed here is broadly along those lines.

Vectorlike leptons (VLL) are an intriguing possibility for …

Robust Determinants Of Happiness: High-Dimensional Bayesian Treatment Of Model Uncertainty, Milivoje Davidovic

Graduate Research Theses & Dissertations

The thesis investigates the most relevant economic and institutional determinants of happiness in some 93 countries worldwide, covering the period 2006-2019. We employ the Bayesian Model Averaging (BMA) fixed effect model (country demeaned and time demeaned) using a working panel data set with 651 observations. Our initial goal is to address the problem of model uncertainty in panel data models of happiness, aiming at selecting a set variables that are likely to be included in as "true" model of happiness. In addition, we aim to investigate the causal relationship running from selected economic and institutional variable to index of happiness. …