Physical Sciences and Mathematics Commons^™

The Applications Of The Tracer Particle Method To Multi-Dimensional Supernova Simulations, Ching-Tsai Lee

Doctoral Dissertations

A new tracer particle implementation has been developed for the 2D supernova code ”CHIMERA”. 2D supernova simulations have been performed for a wide range of progenitors, between 10 and 25 solar mass. In the case of the Heger12 model, we have obtained a successful explosion. Analysis of the tracer particle data generated by supernova simulations reveals the aspherical geometry of the ejecta. Using the hydrodynamic trajectories provided by the tracer particles, we have performed the nucleosynthesis calculations in the post processing approximation, including the effects of neutrino captures, to understand the nucleosynthesis consequences of these models.

The Qse-Reduced Nuclear Reaction Network For Silicon Burning, Suzanne T. Parete-Koon

Doctoral Dissertations

Iron and neighboring nuclei are formed by silicon burning in massive stars before core collapse and during supernova outbursts. Complete and incomplete silicon burning is responsible for the production of a wide range of nuclei with atomic mass numbers from 28 to 70. Because of the large number of nuclei involved, accurate modeling of these nucleosynthetic stages is computationally expensive. For this reason, hydrodynamic models of supernovae often employ a limited set of nuclei to track the nuclear energy generation until nuclear statistical equilibrium is reached. These limited approximations do not include many of the reaction channels important for the …

The Rational Design And Lithographic Fabrication Of Surface Enhanced Raman Spectroscopy Substrates, Jenny M. Oran

Doctoral Dissertations

The analytical capabilities of surface-enhanced Raman spectroscopy (SERS) reside in the performance characteristics of the SERS-active substrate. Signal enhancement observed in SERS is attributable to the presence of noble metal nanostructures on substrate surfaces. The rational design and control of variables such as shape and size, and distribution, density, and spacing of these nanostructures can lead to substrates that have greater analytical sensitivity and yield more reproducible enhancement. Through systematic control of the morphology of our SERS substrates, we have created ordered periodic arrays as well as random aggregates of nanoscale particles using electron beam lithography (EBL). A unique aspect …

Addressing Challenges In A Graph-Based Analysis Of High-Throughput Biological Data, Andy D. Perkins

Doctoral Dissertations

Graph-based methods used in the analysis of DNA microarray technology can be powerful tools in the elucidation of biological relationships. As these methods are developed and applied to various types of data, challenges arise that test the limits of current algorithms. These challenges arise in all phases of data analysis: data normalization, modeling biological networks, and interpreting results. Spectral graph theory methods are investigated as means of threshold selection, a key step in constructing graphical models of biological data. Also important in constructing graphs is the selection of an appropriate gene-gene similarity metric, and an overview of similarity profiles for …

Generating Genetic Resources For Phytophthora Capsici (L.) And Studying P. Capsici And Phytophthora Hybrids In Peru, Oscar Pietro Hurtado-Gonzales

Doctoral Dissertations

The genus Phytophthora includes more than 90 described species infecting over 1000 plant species. Population studies were conducted to investigate the survival and spread of P. capsici in the Peruvian coastal region. A total of 227 P. capsici isolates, recovered at widely distant localities from 2005-2007, were fingerprinted with AFLPs and SNP genotyping. A clonal population (PcPE-1) represented by 221 isolates was found to be distributed throughout the country. Atypical isolates of P. nicotianae were isolated from loquat trees in Peru and nuclear (internal transcribed spacer [ITS], the phenol acid carboxylase gene, and AFLPs) and mitochondrial genotyping (cytochrome oxidase gene …

Fusion Reaction Cross-Section Measurements Near 100Sn, Elton Lewis Freeman

Masters Theses

This thesis describes the measurement of production rates of A=109 isobars produced with beams of ⁵⁴Fe ions accelerated to 207 MeV bombarding ⁵⁸Ni target. The reaction products have been electromagnetically separated according to their mass over charge ratio and implanted into a semiconductor detector. The spontaneous decay radiation from the implanted radioactive isobars has been measured in a detection system with known detection efficiency, enabling to determine absolute intensities of observed isotopes. Known branching ratios of alpha decays of ¹⁰⁹Xe, ¹⁰⁹Te, proton decay of ¹⁰⁹I and beta delayed gamma radiation of ¹⁰⁹Te and ^{109 …}

Quantum Monte Carlo Simulations Of Many-Dimensional Harmonic Oscillators: A Study Of 2Nd And 4Th Order Propagators, Brent-Jon Bjorgvin Magnusson

Masters Theses

Because the Schrödinger equation cannot be solved analytically for systems larger than hydrogen, approximate solution methods must be applied to study systems of chemical interest. Quantum Monte Carlo is one of these methods. Quantum Monte Carlo simulations involve the diffusion of walkers through configuration space and necessitate the use of one of two imaginary time propagators, 2^nd or 4^th order. The choice of the propagator implemented depends on a balance between accuracy and efficiency. Obtaining accurate solutions is the primary objective; once this is accomplished, finding ways to make the simulations efficient is the next intention. Using a …

Assembly And Evaluation Of A Multi-Functional Heat Pulse Probe For Measurement Of Soil Properties, Andrew Conrad Sherfy

Masters Theses

A device capable of estimating soil properties quickly and accurately is of great worth to individuals in many disciplines. The multi-functional heat pulse probe (MFHPP) is an instrument which allows for simultaneous in situ measurements of soil heat capacity, thermal conductivity, thermal diffusivity, water content, water flux density, and electrical conductivity. Previous studies showed this device exhibits instrumentation and model limitations which reduce its measurement accuracy. It is important for the future use of the MFHPP to fully investigate sources of error, increase the range of testing and develop improvements to alleviate these issues.

The main objectives of this study …

Relationship Between Slug-Test And Effective Hydraulic Conductivities For 2-Dimensional Heterogeneous Aquifers, Richard Walker Donat

Masters Theses

Slug tests are one of the most common field tests used by hydrogeologists to evaluate the hydraulic conductivity of an aquifer system. Steady-state and transient (slug test) numerical simulations were run in 37, 2-dimensional randomized multifractal hydraulic conductivity fields. Each field consisted of 59,049 individual saturated hydraulic conductivity (K) values with varying numbers of hydrofacies and different degrees of spatial heterogeneity. The K_eff values were determined by examining the flux in and out of the steady-state numerical model. The K_slug values were determined by adding a slug of water to the center node of the field and evaluating …

Simulation Of Single Molecule Trapping In A Nanochannel, William Neil Robinson

Masters Theses

Trapping of single fluorescent molecules in solution is numerically simulated. Optical trapping provides insufficient force for trapping molecules much smaller than the optical wavelength. Instead, a means for trapping by sensing the molecule position and applying real-time feedback of flow to compensate diffusional displacement is used. The solution is contained in a nanochannel, reducing the problem to one spatial dimension. The position of the molecule is estimated from the fluorescence signals generated by two focused laser beams, which originate from a single laser source that is split and temporally alternated between the two focal spots. Photon collection is time gated, …

Using Automated Task Solution Synthesis To Generate Critical Junctures For Management Of Planned And Reactive Cooperation Between A Human-Controlled Blimp And An Autonomous Ground Robot, Christopher M. Reardon

Masters Theses

This thesis documents the use of an approach for automated task solution synthesis that algorithmically and automatically identifies periods during which a team of less-than-fully capable robots benefit from tightly-coupled, coordinated, cooperative behavior.

I test two hypotheses: 1) That a team’s performance can be increased by cooperating during certain specific periods of a mission and 2) That these periods can be identified automatically and algorithmically. I also demonstrate how identification of cooperative periods can be performed both off-line prior to the application and reactively during mission execution.

I validate these premises in a real-world experiment using a human-piloted Unmanned Aerial …

Analyzing The Effects Of Coupons And Promotion In The Grocery Retail Sector, Milena Hanna Chotard

Masters Theses

Modern scanner technology is pervasive throughout the retailing sector of the economy and is almost universal in the food retail industry. Along with loyalty programs, it has led to the development of massive databases which accurately and proficiently track the purchasing habits of customers. Making use of this information is one of the most important efforts in the management of this sector to further increase profitability.

This thesis explores the application of several statistical techniques to extract specific information from two large databases of customer purchasing behavior at a major US grocery chain. In particular, we first focus on the …

The Synthesis And Stability Of Endohedral Actinium-225(225Ac@C60), Jofa Gideon Mwakisege

Masters Theses

Due to their chemical and thermodynamic stability, fullerenes could play an important role in encapsulation of radionuclides for applications in radio-immunotherapy. In this thesis, we report the first synthesis of actinium endohedral fullerenes. The alpha-emitter Actinium-225 (²²⁵Ac, t_1/2 =10 d) was trapped in fullerenes by the direct current (D.C) arc discharge-catcher method in a He atmosphere. Endohedral ²²⁵Ac and the bulk of fullerene C₆₀ was dissolved from the catcher electrode (a Pt disk covered with a thin layer of C₆₀) in toluene under N₂, and converted to the malonic ester derivative. …

L-Encoder: Video Transcoding In The Logistical Network, Harold Thomas Gonzales

Masters Theses

Transcoding, the transformation of digital information from one encoding format to another, is a prominent operation in the realm of digital video and audio. This process of changing the encoding formats of multimedia files and streams is now a common task for many users due in part to the prevalence of portable media players and consumer electronic devices for digital media, which place constraints on the file and stream formats they can play. The transcoding process is often both data and compute intensive due to both the large data requirements of modern media formats from sources such as HDTV and …

Novel Approaches To Prepare And Utilize Sers Substrates: Multiplex Microfluidics And Nanotransfer Printing, Nahla A. Abu-Hatab

Doctoral Dissertations

Over the past few decades, surface enhanced Raman spectroscopy (SERS) has garnered respect as an analytical technique with significant chemical and biological applications. SERS is important for the life sciences because it can provide trace level detection and a high level of molecular structure information. The development of quantitative, highly sensitive substrates requires control over size, shape, and position of metal nanoparticles which function as the SERS active medium. Thus, creating and successfully implementing a sensitive, reproducible, and robust SERS active substrate continues to be a challenging ask. Its future development depends critically on techniques for lithography and nanofabrication. Herein, …

Approaches To Generating Selectivity In Microcantilever Sensors, Peter J. Chapman

Doctoral Dissertations

Microcantilever (MC) sensors have emerged as sensing transducers that offer greater sensitivity than comparable sensors due in large part to their very small dimensions. MCs have been utilized in many chemical sensing applications. Not only do MCs demonstrate greater sensitivity, but they also are relatively low in cost, they can be used in an array format, and they can be integrated into on-chip electronic circuitry.

While MC sensors demonstrate great sensitivity, an area of weakness that MC sensors must overcome is that of selectivity. The response of a MC sensor to analyte is mechanical; these mechanical responses lack the information …

Materials Chemistry Of Nanocubes And Mesoporous Silicas: Characterization And Adsorption Studies, Sami Ziad Chanaa

Doctoral Dissertations

Metal oxides (MO) and their surfaces play a vital role in numerous phenomena, including metal surface passivation, catalysis, integrated optoelectronic technology, and pollution monitoring via solid-state gas sensing. This experimental study seeks to aid in the development of accurate and predictive theoretical models of the potential energy surfaces described in the interaction of these small molecules with the magnesium oxide (MgO) substrate. MgO, with its structural simplicity and capacity to be fabricated with a predominantly (100) exposed face, is an ideal representative of the MO family popular for both experimental and theoretical studies. Using high-resolution volumetric adsorption isotherms, a thermodynamic …

Creation Of An Ice Hockey Tradition In The South, Daryl Paul Wenner

Doctoral Dissertations

This dissertation examines the links between culture and tradition. It argues that traditions are influenced by the underlying cultural foundations from which they develop. It also argues that as traits diffuse between cultures, they do not do so “as is” but are interpreted by the recipient culture group and altered by their cultural beliefs. Because of the alterations that occur, the diffusion event is not a one-directional incident. The alteration of the trait causes the original exporter to evaluate the changes made, thereby altering the source culture’s opinion of the recipient group.

The dissertation uses a three-stage model to examine …

Investigating The Petrogenesis Of The Basaltic Crust Of Asteroid 4 Vesta: A Combined Petrologic-Spectral Study Of The Unbrecciated Eucrites, Rhiannon Gwenllian Mayne

Doctoral Dissertations

The Dawn mission, which launched in September 2007, will orbit and analyze two of the largest asteroids, 4 Vesta and 1 Ceres. These small, proto-planetary bodies retain a record of the conditions and processes that occurred in the early history of the Solar System, and, as such, provide us with a tool to understand its formation and evolution. Additional information can also be gleaned from the meteorite samples derived from such objects. This dissertation aims to increase understanding of the formation of the basaltic crust of the asteroid Vesta, and the lithologic variety that exists within it, by studying the …

Treeline Responses To Climate Change In High-Elevation Landscapes Of Western Montana, U.S.A., David F. Mann

Doctoral Dissertations

The purpose of this research was to use whitebark pine trees at three major sites in western Montana to: (1) determine tree species response to climate, (2) reconstruct past climate conditions, (3) determine the effects of climate shifts on treeline, and (4) reconstruct fire history from fire-scar data. I collected samples from whitebark pine and subalpine fir and from remnant whitebark pine in the western Beaverhead-Deerlodge and Lolo National Forests.

In the climate response analysis, the Palmer Drought Severity Index (PDSI) had the highest correlations with whitebark pine growth. The strongest relationship occurred in the previous year’s June and July. …

Development Of A Simulation System For Testing Hardwood Plantation Silviculture, Christopher Michael Oswalt

Doctoral Dissertations

Hardwood plantations are becoming increasingly important in the United States. To date, many foresters have relied on a conifer plantation model as the basis of establishing and managing hardwood plantations. The monospecific approach suggested by the conifer plantation model does not appear to provide for the development of quality hardwood logs similar to those found in natural hardwood stands. Thus, there is interest in creating mixed species plantations to simulate natural hardwood stand development.

A simulation system, CherrybarkSQ, was developed to provide a platform for investigating the impacts of mixed species management of hardwood plantations on the stem quality of …

Determination Of Mineral Abundances In Ordinary Chondrites Using Powder X-Ray Diffraction: Applications To Parent Body Processes And Asteroid Spectroscopy, Tasha L. Dunn

Doctoral Dissertations

The ordinary chondrites, the most abundant group of meteorites, are divided into three chemical groups (H, L, and LL), which are distinguished based on variations in bulk composition and iron content. Although ordinary chondrites are relatively abundant, our understanding of their formation has been hampered by an inability to accurately measure the abundances of minerals that they contain. Here I use power x-ray diffraction (XRD) to quantify the modal abundances of 48 unbrecciated ordinary chondrite falls, which represent the complete petrologic range of equilibrated ordinary chondrites (types 4-6).

Although the degree of metamorphism varies within each ordinary chondrite group, many …

Establishment Of A Structure-Activity Relationship In Heterogeneous Titanosilicate Catalysts For Olefin Epoxidation Via A Building Block Method, Geoffrey T. Eldridge

Doctoral Dissertations

The non-aqueous building block (NABB) method is a synthetic method that has the goal of producing atomically dispersed, well-defined, single-site heterogeneous catalysts. The active sites of these catalysts are able to be structured on the nanometer scale using the process of sequential additions. The method is designed in such a manner that it should be able to produce a series of catalysts each with a unique, well-defined, single active site. This series of catalysts can then be used to elucidate the structure-activity relationship for the active site in a particular chemical reaction.

In this dissertation a new building block, …

Synthesis, Characterization, And Applications Of Responsive Polymer Brush-Grafted Particles, Dejin Li

Doctoral Dissertations

In this dissertation, I present the synthesis, characterization, and applications of responsive polymer brush-grafted silica/crosslinked polymeric particles. The polymer brush-grafted particles were synthesized by surface-initiated "living"/controlled radical polymerizations from initiator-functionalized particles in the presence of free initiators. Two types of core particles were used in my research. One was silica particles, which were synthesized by Stöber method. The other one was crosslinked PtBA particles, which were prepared by seeded emulsion polymerization. The responsive properties of the grafted polymer brushes were characterized with ¹H NMR and Dynamic Light Scattering.

Nanomagnets: Magnetic Properties And Inelastic Neutron Scattering Studies, Jason T. Haraldsen

Doctoral Dissertations

In this thesis, small quantum spin systems, known as nano-magnets or molecular magnets, have been investigated. This is an area of great interest in the development of nanotechnology and quantum computers. Previous research on molecular magnets has concentrated on large, complex materials, which have many magnetic ions competing for superexchange pathways. Due to the large number of magnetic ions, the Hamiltonians resulted in very large Hilbert spaces, which makes it difficult for the magnetic interactions to be characterized and analyzed. Through the analysis of smaller and simpler magnetic clusters, insight can be gained from the interactions of the magnetic ions …

Imaging By Detection Of Infrared Photons Using Arrays Of Uncooled Micromechanical Detectors, Dragoslav Grbovic

Doctoral Dissertations

The objective of this dissertation was to investigate the possibility of uncooled infrared imaging using arrays of optically-probed micromechanical detectors. This approach offered simplified design, improved reliability and lower cost, while attaining the performance approaching that contemporary uncooled imagers. Micromechanical infrared detectors undergo deformation due to the bimetallic effect when they absorb infrared photons. The performance improvements were sought through changes in structural design such as modification and simplification of detector geometry as well as changes in the choice of materials. Detector arrays were designed, fabricated and subsequently integrated into the imaging system and relevant parameters, describing the sensitivity and …

A Finite State Machine Approach To Cluster Identification Using The Hoshen-Kopelman Algorithm, Matthew L. Aldridge

Doctoral Dissertations

The purpose of this study was to develop an efficient finite state machine implementation of the eponymous Hoshen-Kopelman cluster identification algorithm using the nearest-eight neighborhood rule suitable to applications such as computer modeling for landscape ecology. The implementation presented in this study was tested using both actual land cover maps, as well as randomly generated data similar to those in the original presentation of the Hoshen-Kopelman algorithm for percolation analysis. The finite state machine implementation clearly outperformed a straightforward adaptation of the original Hoshen-Kopelman algorithm on either data type. Research was also conducted to explore the finite state machine's performance …

Optimization Of Cosmological Simulations With Artificial Intelligence, Jay Billings

Masters Theses

Galaxy collisions are an important part of the large-scale structure of the Universe and an important catalyst for intragalactic processes like star formation. Therefore, realistic models of these interactions are an important part of any theory that plans to accurately describe the evolutionary processes of the Universe and, given the size of the problem, efficient computation and data analysis are key. This dissertation presents a proof-of-concept that an artificial intelligence suite, nominally composed of a genetic algorithm and neural network, can optimize the search of the galaxy collision parameter space. Furthermore, this dissertation discusses the possibility that this method can …

Parallel Simulation Of Individual-Based, Physiologically-Structured Population And Predator-Prey Ecology Models, Jeffrey A. Nichols

Doctoral Dissertations

Utilizing as testbeds physiologically-structured, individual-based models for fish and Daphnia populations, techniques for the parallelization of the simulation are developed and analyzed. The techniques developed are generally applicable to individual-based models. For rapidly reproducing populations like Daphnia which are load balanced, then global birth combining is required. Super-scalar speedup was observed in simulations on multi-core desktop computers.

The two populations are combined via a size-structured predation module into a predator-prey system with sharing of resource weighted by relative mass. The individual-based structure requires multiple stages to complete predation.

Two different styles of parallelization are presented. The first distributes both populations. …

Zero-Divisor Graphs, Commutative Rings Of Quotients, And Boolean Algebras, John D. Lagrange

Doctoral Dissertations

The zero-divisor graph of a commutative ring is the graph whose vertices are the nonzero zero-divisors of the ring such that distinct vertices are adjacent if and only if their product is zero. We use this construction to study the interplay between ring-theoretic and graph-theoretic properties. Of particular interest are Boolean rings and commutative rings of quotients.