Physical Sciences and Mathematics Commons^™

Assessing The Impacts Of Electronic Commerce Diffusion On Development, Gerard De Leoz, Sajda Qureshi, Lotfollah Najjar

Information Systems and Quantitative Analysis Faculty Proceedings & Presentations

While the concept of economic development has been widely used to understand the health and wealth of countries, it is accepted that the access to the internet for electronic commerce transactions enable generation in income and improvements in lives. However, with the rise of disparities in income within countries, electronic commerce opportunities can be limited to the few with internet access. In this paper, we investigate how e-commerce diffusion affects economic development and factors of electronic commerce diffusion that promote or impede economic development. Using data available through international data collection agencies, we analyze three ASEAN members with relatively close …

Unraveling Controls On Fracture Stratigraphy In Carbonates: The Influence Of Regional Stress, Mechanical Properties, And Diagenesis, Matthew H. Peppers

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Fracture characteristics analyzed from outcrops provide key insights into the migration pathways of subsurface hydrocarbons, and allow for a detailed understanding of the tectonic history in an area. This study looks to assess the impacts that various controlling factors have on the development of fracture characteristics. To complete this objective, a succession of Ordovician to Mississippian rocks was examined. The logged section includes the Cotter Dolomite, Chattanooga Shale, St. Joe Formation, and the Boone Formation (subdivided into informal Upper and Lower members). Located in northwestern Arkansas and southwestern Missouri, data were collected from roadcut exposures along Highway 71. Collected fracture …

Bioenergetics And Habitat Suitability Models For The Chinese Mystery Snail (Bellamya Chinensis), Danielle M. Haak

School of Natural Resources: Dissertations, Theses, and Student Research

Relatively little is known about the invasive Chinese mystery snail (Bellamya chinensis). This research aims to elucidate some of the mystery surrounding this species. First, we place the species in context with other invasive freshwater snails of the USA and Canada, identifying current information gaps, categorizing shared characteristics among families and species, and comparing functional roles and ecological effects of freshwater snails. We conclude that more focus needs to be directed to regulating the aquarium, pet, and food trades if we are serious about preventing future invasions. Next, we develop a bioenergetics model for the species by quantifying …

Shorebird Migratory Stopover Responses To Local And Regional Change: Habitat Decisions In A Vanishing Landscape, Caitlyn Gillespie

School of Natural Resources: Dissertations, Theses, and Student Research

Understanding the consequences of anthropogenic change for migratory species is challenging because although they have evolved to cope with environmental uncertainty, migrants still rely on predictable relationships within and among habitats to make informed decisions. Calidris shorebirds rely on ephemeral wetlands during northward migration through mid-continental North America, where favorable habitat conditions are annually and regionally unpredictable and increasingly altered by land-use change. During spring 2013 and 2014, we assessed Calidris habitat use in the Rainwater Basin (RWB) and the Prairie Pothole Region (PPR) at both local and landscape scales. Although anthropogenic change has altered the wetland landscape in both …

Plant Diversity Affects Performance Of Invasive Thistles In Restored Nebraska Grasslands, Katilyn J. Price

School of Natural Resources: Dissertations, Theses, and Student Research

Invasive plant species threaten native grasslands, affecting nutrient cycling, biodiversity, wildlife habitat, and usable land for production. Consequently, preventing establishment of invasive species is critical before removal becomes difficult and expensive. The purpose of this study was to examine the effects of grassland plant diversity on musk thistle (Carduus nutans) and Canada thistle (Cirsium arvense) establishment and determine which environmental factors (light penetration, soil moisture, plant diversity, and soil nitrogen) account for resistance to invasions. In a field experiment at The Nature Conservancy’s Wood River site (Nebraska), the two invasive thistle species were planted into replicated …

Hydrologic Mediation Of The Spatial And Temporal Variability Of The Soil Carbon Dioxide Stable Isotopic Composition Of A Subalpine Watershed, Theresa Marie Lorenzo

School of Natural Resources: Dissertations, Theses, and Student Research

The stable carbon isotopic composition of CO₂ (δ¹³C-CO₂) has been studied as an indicator of changes in ecosystem CO₂ exchange. Soil moisture is an important factor in ecosystem CO₂ exchange through its influence on physiological and soil physical processes. However, the majority of previous research analyzing the influence of soil moisture on soil and soil-respired δ¹³C-CO₂ has been conducted with limited consideration of topographical variation, which controls the distribution of soil moisture across a landscape. This study characterized the stable isotopic composition (δ¹³C) and concentrations of soil CO …

Acute Toxicity Of Β-N-Methylamino-L-Alanine (Bmaa) To Fathead Minnow (Pimephales Promelas) And Zebrafish (Danio Rerio), Jiayi Wang

School of Natural Resources: Dissertations, Theses, and Student Research

β-N-methylamino-L-alanine (BMAA) is a neurotoxic amino acid produced by most species of cyanobacteria. Exposure to BMAA has been hypothesized as a cause of ALS and possibly Parkinson’s and Alzheimer’s diseases for several decades. Both in vitro and in vivo experiments revealed that exposure to elevated concentrations of BMAA can damage motor neurons and cause motor dysfunctions. However, the exact mechanism of BMAA-induced neurotoxicity has not been well understood.

Based on the available literature and in spite of its water-soluble and non-protein nature, BMAA appears to be able to bioaccumulate in organisms. The ubiquity of cyanobacteria and the potential for bioaccumulation …

Genetic And Morphological Variation In Ecuadorian Astroblepid Catfishes, Katherine M. Lawry

School of Natural Resources: Dissertations, Theses, and Student Research

The Andean ichthyofauna remains a poorly understood component of Neotropical biodiversity, and stands in stark contrast to the lowland ichthyofauna in terms of number of species and range of distribution. The Climate Variability Hypothesis (CVH) predicts rapid turnover of species along elevational gradients in tropical climates, but it remains unclear whether stream fishes follow this pattern. Astroblepid catfishes represent a distinctive assemblage of species that inhabit high elevation streams throughout the Andes from Panama to Bolivia, and constitute the only native fish family present in the Ecuadorian highland region. In this research, population samples of Astroblepids collected throughout Ecuador’s Napo …

Angular Dependence Of The Emission From The Intrinsic Josephson Junction In Pie-Shaped Wedge Triangular Bscco Mesas, Manuel Morales

HIM 1990-2015

The purpose of this thesis is to determine the radiation patterns from an acute isosceles triangular superconducting mesa modeled by a pie-shaped geometry. The terahertz band lies between the microwave and infrared regions of the electromagnetic spectrum. The terahertz radiation from atomic-scale layered superconducting mesas is caused by the tunneling of electron pairs in the ac-Josephson effect. To determine the terahertz power radiated per unit solid angle of an acute isosceles triangular superconducting mesa, a model was employed in which the shape of the mesa is approximated as a pie-shaped wedge. This model is shown to have an accuracy of …

Sparsification Of Social Networks Using Random Walks, Bryan Wilder

HIM 1990-2015

Analysis of large network datasets has become increasingly important. Algorithms have been designed to find many kinds of structure, with numerous applications across the social and biological sciences. However, a tradeoff is always present between accuracy and scalability; otherwise promising techniques can be computationally infeasible when applied to networks with huge numbers of nodes and edges. One way of extending the reach of network analysis is to sparsify the graph by retaining only a subset of its edges. The reduced network could prove much more tractable. For this thesis, I propose a new sparsification algorithm that preserves the properties of …

Microfluidic Syntheses Of Pet Radiotracers Via Fluorodenitration, Thomas Madison Moore

Doctoral Dissertations

This research study is focused on the syntheses of radiotracers for use in positron emission tomography [PET] via fluorodenitration and fluorodehalogenation under microfluidic conditions. Methodology has been developed for radiolabeling via fluorodenitration under microfluidic conditions and comparisons made to dehalogenation reactions. Developmental work was carried out on commercially available compounds containing a variety of functional groups. Subsequent production of radiotracers has been performed with precursors provided by collaborators as well as those synthesized in our laboratory.

Synthesis And Characterization Of Support-Modified Nanoparticle-Based Catalysts And Mixed Oxide Catalysts For Low Temperature Co Oxidation, Andrew Justin Binder

Doctoral Dissertations

Heterogeneous catalysts are responsible for billions of dollars of industrial output and have a profound, if often understated, effect on our everyday lives. New catalyst technologies and methods to enhance existing catalysts are essential to meeting consumer demands and overcoming environmental concerns. This dissertation focuses on the development of catalysts for low temperature carbon monoxide oxidation. CO [carbon monoxide] oxidation is often used as a probe reaction to test overall oxidation activity of a given catalyst and is an important reaction in the elimination of toxic pollutants from automotive exhaust streams. The work included here presents three new heterogeneous catalysts …

Studies Of Metalloporphyrins And Tantalum Amide Imide Compounds, Seth Carlton Hunter

Doctoral Dissertations

The focus of this dissertation is on two different subjects. The first examines the magnetic and structural properties of metalloporphyrins. In these studies, neutrons were used to probe the magnetic properties of metalloporphyrins. Insight on the structural properties of metalloporphyrins was also gained by examining the intermolecular interactions in the solid state. The second subject is the synthesis and characterization of new tantalum complexes and studies of their reactions with O₂ [dioxygen]. These complexes are potential precursors to make metal oxide and metal nitride thin films.

In the first part of this dissertation, the zero-field parameters D have been …

An Investigation Of Inorganic Compound Scattering., Karl Jay Bernstein

Doctoral Dissertations

Raman and its associated forms of spectroscopy are powerful tools that have been under-utilized. Presented within are three inorganic compounds studied with some form of Raman spectroscopy: normal Raman, hyper-Raman (HR), surface-enhanced Raman spectroscopy (SERS), surface-enhanced hyper-Raman spectroscopy (SEHRS), or resonance Raman spectroscopy (RR).

The first study involves the investigation of phosphine binding with silver metal. Phosphines find wide use in synthetic circles yet have had little study into their method of binding, unlike similar compounds comprised of sulfur. In order to understand the binding of phosphines, several tertiary phosphines, secondary phosphines and secondary phosphine oxides are examined with SERS. …

Oxygen Reduction Reaction By Copper Complex Based Electrocatalysts, Congling Zhang

Doctoral Dissertations

My research focuses on catalysis of oxygen reduction reaction (ORR) by a series of Cu(II) [copper with positive two valence] -1,2,4-triazole complex-based electrocatalysts at the cathode of PEMFC (polymer electrolyte membrane fuel cell), an efficient and environmental friendly energy conversion system compared to internal combustion engines in use today. The sluggish kinetics of ORR considerably limited the performance of PEMFCs. Understanding of ORR mechanism is important for developing affordable, active and durable ORR catalysts for such devices.

The first part of my work focused on improving the ORR performance of Cu(II)-1,2,4-triazole complex-based catalysts in an acidic environment by exploring synthesis …

Event Localization In Bulk Scintillator Crystals Using Optical Coded Apertures, Joshua Brian Braverman

Doctoral Dissertations

Scintillation-based radiation detectors provide an effective method to detect radioactive materials. In medical physics, astrophysics, and national security technology oftentimes it is optimal to have the ability to localize a radioactive interaction in a scintillator to as small a region as possible within the crystal. Current methods rely on the ability to centroid a light spot as read onto a phototransducer (commonly a photomultiplier tube), and due to the typical width of the light spot when it reaches the phototransducer, the resolution is generally limited to several millimeters. One method to achieve a finer resolution is to use a segmented …

Elucidating The Impact Of Roseophage On Roseobacter Metabolism And Marine Nutrient Cycles, Nana Yaw Darko Ankrah

Doctoral Dissertations

As the most abundant biological entities in marine environments, viruses are an important component of marine food webs. The activity of viruses contributes significantly to the mortality of marine microorganisms, ultimately influencing biological function and chemical composition of aquatic systems by impacting species composition and flow of carbon, nitrogen and other nutrients. Despite the growing recognition that viral activity contributes to marine biogeochemical cycles, the extent to which virus infection reshapes host metabolism and the effect of this alteration on the composition of host lysate remains poorly understood. Additionally, the degree to which natural bacterioplankton communities metabolise the released lysate …

Neuroscience-Inspired Dynamic Architectures, Catherine Dorothy Schuman

Doctoral Dissertations

Biological brains are some of the most powerful computational devices on Earth. Computer scientists have long drawn inspiration from neuroscience to produce computational tools. This work introduces neuroscience-inspired dynamic architectures (NIDA), spiking neural networks embedded in a geometric space that exhibit dynamic behavior. A neuromorphic hardware implementation based on NIDA networks, Dynamic Adaptive Neural Network Array (DANNA), is discussed. Neuromorphic implementations are one alternative/complement to traditional von Neumann computation. A method for designing/training NIDA networks, based on evolutionary optimization, is introduced. We demonstrate the utility of NIDA networks on classification tasks, a control task, and an anomaly detection task. There …

Novel Physical Properties Of Non-Trivial Magnetic Materials: Cr1/3nbs2, Mnsi And Fe3gete2, Jieyu Yi

Doctoral Dissertations

Helimagnets and quasi-two-dimensional layered materials have attracted much recent interest due to their rich physical properties and potential for spintronics applications. In this dissertation, the helimagnets Cr_1/3NbS₂ [chromium one-third niobium disulfide] and thin-film MnSi [manganese silicide] as well as the layered magnetic material Fe₃GeTe₂ [iron three germanium ditelluride] were extensively and carefully studied. Cr_1/3NbS₂ was previously reported to be helimagnet with a transition temperature of approximately 120 K. Cr_1/3NbS₂ has a layered structure with Cr³⁺ ions intercalating between NbS­₂ sheets, and is easily cleaved. Using in-situ …

Distinguishing Primary Versus Secondary Geochemical And Silicon Isotope Characteristics Of Precambrian Chert And Iron Formation, Latisha Ashley Brengman

Doctoral Dissertations

Precambrian chert and banded iron formation (BIF) are defined as chemical sediments precipitated directly from seawater. As such, their geochemistry, including trace elements, rare earth elements (REE), and isotopes (O, Si) may preserve Precambrian seawater conditions. However, the chemical signature of these rocks may not simply reflect seawater, because hydrothermal interactions and metasomatism may produce rocks that petrographically and chemically resemble chert and BIF, including seawater-like compositional characteristics acquired during mineral replacement. Interpreting the major-, trace-, and rare-earth element signatures of these rocks requires the identification of geochemical and isotopic fingerprints that differentiate rocks formed from chemical sedimentation from rocks …

The Fabrication Of Micro- And Nano- Scale Deterministic And Stochastic Pillar Arrays For Planar Separations, Teresa Byers Kirchner

Doctoral Dissertations

Planar chromatography, unlike high performance liquid chromatography (HPLC), has not experienced a significant evolution in stationary phase media since the development of the technique. This has lead HPLC to become a much more popular and robust analytical method. Main factors that contribute to improved performance of chromatographic systems include a reduction in particle size, homogeneity of the stationary phase, and an increase in velocity of the mobile phase. In general, a reduction in particle size should lead to an improvement in the performance of all chromatography systems. However, the main obstacle of improving the performance of planar chromatography systems is …

Computational Framework For Small Animal Spect Imaging: Simulation And Reconstruction, Sang Hyeb Lee

Doctoral Dissertations

Small animal Single Photon Emission Computed Tomography (SPECT) has been an invaluable asset in biomedical science since this non-invasive imaging technique allows the longitudinal studies of animal models of human diseases. However, the image degradation caused by non-stationary collimator-detector response and single photon emitting nature of SPECT makes it difficult to provide a quantitative measure of 3D radio-pharmaceutical distribution inside the patient. Moreover, this problem exacerbates when an intra-peritoneal X-ray contrast agent is injected into a mouse for low-energy radiotracers.

In this dissertation, we design and develop a complete computational framework for the entire SPECT scan procedure from the radio-pharmaceutical …

Studies Of Strongly Correlated Electron Systems Using Neutron Scattering, Yuen Yiu

Doctoral Dissertations

The world presents many natural and man-made crises and challenges that require scientific solutions. Condensed matter physics is one of the most influential and solution oriented disciplines in science. The field saw a significant rise in popularity especially during the past century as mankind enters the Information Age, when energy and computing related technologies become ubiquitous. This technological progress has been driven by efforts from scientists and engineers, through the synthesis, understanding, and implementation of new materials. Condensed matter physicists strive to solve puzzles at the frontier of material research. In the 21st century we have many advance tools at …

Computational Electrodynamics And Second Hyper-Raman Scattering, Philip Dwaine Simmons Jr.

Doctoral Dissertations

Surface-enhanced second hyper-Raman spectroscopy is a type of nonlinear light scattering in which three photons are simultaneously annihilated to produce one photon whose color is slightly shifted from its third harmonic. This process, while incredibly weak, can be magnified by many orders of magnitude with the aid of plasmonic substrates. In this dissertation, three different studies are presented probing both the nature of plasmonics and nonlinear Raman scattering. In the first, nanoparticle aggregates were dosed with two isotopologues of Rhodamine 6G to determine single-molecule activity. Plasmon maps of the aggregates were then generated from electron energy-loss spectroscopy (EELS) and 3D …

Monte Carlo Methods In Finance, Je Guk Kim

Doctoral Dissertations

Monte Carlo method has received significant consideration from the context of quantitative finance mainly due to its ease of implementation for complex problems in the field. Among topics of its application to finance, we address two topics: (1) optimal importance sampling for the Laplace transform of exponential Brownian functionals and (2) analysis on the convergence of quasi-regression method for pricing American option. In the first part of this dissertation, we present an asymptotically optimal importance sampling method for Monte Carlo simulation of the Laplace transform of exponential Brownian functionals via Large deviations principle and calculus of variations the closed form …

Beta Decay Of Neutron-Rich Isotopes Of Zinc And Gallium, Mohammad Faleh M. Al-Shudifat

Doctoral Dissertations

Beta-decays of neutron-rich nuclei near the doubly magic ⁷⁸Ni [78Ni] were studied at the Holifield Radioactive Ion Beam Facility. The half-life and the gamma-gamma coincidence spectra were used to study the nuclear structure. A new ^82,83Zn [82Zn, 83Zn] decay-scheme was built, where a 71±7% beta-delayed neutron branching ratio was assigned in ⁸²Zn [82Zn] decay. New gamma-ray lines and energy levels observed in ^82,83Ga [82Ga, 83Ga] beta-decay were used to update previously reported decay-schemes. The experimental results were compared to shell model calculations, which postulate the existence of Gamow-Teller transitions in these decays. The half-lives of 155±17 …

Directed Energy For Relativistic Propulsion And Interstellar Communications, Philip Lubin, Gary Hughes, J Bible, Isabella Johansson

Statistics

An orbital planetary defense system that is also capable of beamed power propulsion allows mildly relativistic spacecraft speeds using existing technologies. While designed to heat the surface of potentially hazardous objects to the evaporation point to mitigate asteroid threats the system is inherently multi-functional with one mode being relativistic beamed spacecraft propulsion. The system is called DE-STAR for Directed Energy Solar Targeting of Asteroids and exploRation. DE-STAR is a proposed orbital platform that is a modular phased array of lasers, powered by the sun. Modular design allows for incremental development, test and initial deployment, lowering cost, minimizing risk and allowing …

Development Of A Tridimensional Measuring Application For Ipads, Michael Casebolt, Nicolas Kouatli, Jack Mullen

Computer Science and Software Engineering

In today’s fast-paced distribution centers workers and management alike are constantly searching for the quickest and most efficient way to package items for distribution. Even with the advancement of app-oriented solutions to a variety of problems across many industries there is a distinct unmet need in distribution environments for an application capable of increasing the efficiency and accuracy of packaging items. This senior project focused on the development and testing of an application utilizing the Structure Three Dimensional Sensor and a 4th generation iPad to scan an object or group of objects to be packaged and determine the overall dimensions …

Virtual Droop Control Framework And Stability Analyses For Microgrids With High Penetration Of Renewables, Ashishkumar Kanubhai Solanki

Theses and Dissertations

Microgrids can provide the most promising means of integrating large amounts of distributed sources into the power grid and can supply reliable power to critical loads. However, managing distributed sources and loads within a microgrid during island and grid-tie modes and during transitions is a challenge. Stable operation of a microgrid is a concern specifically during the starting of motor loads, switching of large loads, and in presence of high penetration of renewable resources. Hence, a generalized control framework is required to regulate microgrid voltage and frequency, maintain power quality, manage Distributed Generations (DG) and ensure microgrid stability. Several control …

Rapid Response Tools And Datasets For Post-Fire Modeling: Linking Earth Observations And Process-Based Hydrological Models To Support Post-Fire Remediation, Mary Ellen Miller, Michael Billmire, William J. Elliot, K. A. Endsley, P. R. Robichaud

Michigan Tech Research Institute Publications

Preparation is key to utilizing Earth Observations and process-based models to support post-wildfire mitigation. Post-fire flooding and erosion can pose a serious threat to life, property and municipal water supplies. Increased runoff and sediment delivery due to the loss of surface cover and fire-induced changes in soil properties are of great concern. Remediation plans and treatments must be developed and implemented before the first major storms in order to be effective. One of the primary sources of information for making remediation decisions is a soil burn severity map derived from Earth Observation data (typically Landsat) that reflects fire induced changes …