Physical Sciences and Mathematics Commons^™

Molecular Dynamics Simulations Using Advanced Sampling And Polarizable Force Fields, Tugba Kucukkal

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Molecular dynamics (MD) simulations were carried out for aqueous dipeptides, water over self-assembled monolayer (SAM) surfaces, and the nicotinic acetylcholine receptor (nAChR) ion channel. The main goal is to use advanced methods to increase the accuracy of molecular dynamics simulations while seeking solutions to problems relevant to chemistry, biophysics and materials science. In addition, activation energies of several cyclodimerization reactions were studied quantum mechanically. The simulations of the aqueous dipeptides and SAM surfaces involve modeling and detailed analysis of interfacial water, which is of interest to a range of fields from biology to materials science. For example, water has a …

Genetic Algorithm Techniques In Climate Changepoint Problems, Shanghong Li

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The first part of this dissertation studies genetic algorithms as a means of estimating the number of changepoints and their locations in a climatic time series. Such methods bypass classical subsegmentation algorithms, which sometimes yield suboptimal conclusions. Minimum description length techniques are introduced. These techniques require optimizing an objective function over all possible changepoint numbers and location times. Our general objective functions allow for correlated data, reference station aspects, and/or non-normal marginal distributions, all common features of climate time series. As an exhaustive evaluation of all changepoint configurations is not possible, the optimization is accomplished via a genetic algorithm that …

An Investigation Into The Interactions Of Gold Nanoparticles With Aquatic Vascular Macrophytes, James Glenn

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Nanomaterials (NMs) have promised lighter, stronger, smaller and more efficient products in areas such as electronics, medicines and even environmental sectors. This investigation started at the base of the food chain and characterized NMs interactions with aquatic plants. Citrate capped gold nanoparticles were used as a model nanoparticle to track fate and gain insight on factors that influence gold nanoparticle (AuNP) bioavailability and absorption. Four species of aquatic macrophytes were investigated. Azolla caroliniana, Myriophyllum simulans, Egeria densa and Myriophyllum aquaticum were selected due to growth habitat, leaf morphology and root structure. Because aquatic plants absorb the majority of their nutrients …

L1 Methods For Shrinkage And Correlation, Jie Shen

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This dissertation explored the idea of L1 norm in solving two statistical problems including multiple linear regression and diagnostic checking in time series. In recent years L1 shrinkage methods have become popular in linear regression as they can achieve simultaneous variable selection and parameter estimation. Their objective functions containing a least squares term and an L1 penalty term which can produce sparse solutions (Fan and Li, 2001). Least absolute shrinkage and selection operator (Lasso) was the first L1 penalized method proposed and has been widely used in practice. But the Lasso estimator has noticeable bias and is inconsistent for variable …

Surface Shape Perception In Volumetric Stereo Displays, Meng Zhu

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In complex volume visualization applications, understanding the displayed objects and their spatial relationships is challenging for several reasons. One of the most important obstacles is that these objects can be translucent and can overlap spatially, making it difficult to understand their spatial structures. However, in many applications, for example medical visualization, it is crucial to have an accurate understanding of the spatial relationships among objects. The addition of visual cues has the potential to help human perception in these visualization tasks. Descriptive line elements, in particular, have been found to be effective in conveying shape information in surface-based graphics as …

Exploratory Synthesis Of New Iron(Ii,Iii)-Containing Polyanion Framework Solids Of Electrochemical And Magnetic Interest, Liurukara Sanjeewa

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The studies demonstrated in this dissertation were primarily focused on the synthesis, structure and property characterizations of iron(II,III) containing framework solids. The scope of this research is threefold: 1) explore new iron(II, III)-containing open framework structures in hopes of creating new materials, useful in the areas of both Li- and Na-ion battery applications; 2) synthesis and characterization of low-dimensional magnetic nanostructures exhibiting novel magnetic properties due to confined magnetic lattices; and 3) conduct structure/property correlation studies to identify the origins of any unusual physical phenomena associated with these new compounds.

In the syntheses of new compounds, molten salt fluxes were …

Arachidonic Acid Reverses The Pyriproxyfen And Ibuprofen Induced Toxicity In Daphnia Magna, Gautam Kumar Ginjupalli

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Healthy reproduction and neonatal sex ratios of Daphnia are crucial to the health of the aquatic ecosystems in which Daphnia play principal roles in trophic transfer of nutrients. Combinations of environmental factors such as availability and quality of diet, overcrowding, hypoxia, reduced photoperiods and fall in ambient temperatures perturb normal parthenogeneic reproduction and induce sexual reproduction through male production. Male production provides a mechanism for overcoming specific stressors such as overcrowding and overwinter pond desiccation. However, it also induces a decrease in the Daphnia population that could have adverse implications on the pond ecosystem that depend on Daphnia . Interestingly, …

Chemical Evolution Of The Neutron-Rich Iron-Group Isotopes And Implications For The Formation Of Fun Cais, Tianhong Yu

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Calcium-aluminum-rich inclusions (CAIs) are millimeter-sized refractory objects found in primitive meteorites. CAIs are considered as some of the first solids to form in the solar system, because they are refractory. FUN CAIs, those with Fractionated and Unknown Nuclear effects, are a small subset of CAIs. These FUN CAIs show correlated excesses and deficits in the neutron-rich iron-group isotopes such as ⁴⁸ Ca and ⁵⁰ Ti which regular CAIs do not. Interestingly, these isotopes are most likely produced infrequently but in huge quantities in a rare class of thermonuclear (Type Ia) supernovae. I propose that the isotopic effects in the neutron-rich …

Approximation In Multiobjective Optimization With Applications, Lakmali Weerasena

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Over the last couple of decades, the field of multiobjective optimization has received much attention in solving real-life optimization problems in science, engineering, economics and other fields where optimal decisions need to be made in the presence of trade-offs between two or more conflicting objective functions. The conflicting nature of objective functions implies a solution set for a multiobjective optimization problem. Obtaining this set is difficult for many reasons, and a variety of approaches for approximating it either partially or entirely have been proposed.

In response to the growing interest in approximation, this research investigates developing a theory and methodology …

Neutron Study Of Structured Polymers At Interfaces, Thusitha Etampawala

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This work focuses on interfacial structure and dynamics of structured polymers in thin films and in solutions using neutron techniques accompanied by atomic force microscopy. We probed polymers with a common theme that were highly segregated either because of presence of ionic groups or topological constraints. In these polymers the interfacial regions often define their function in different applications such as clean energy, printing adhesions and drug delivery systems. Thin film studies include systems of polystyrene/sulfonated polystyrene, a rigid sulfonated polyphenylene and polystyrene three-arm stars/linear polystyrene. The first two systems include ionic components and the last exhibits topological constraints. Polystyrene …

Ecology And Impacts Of Coyotes (Canis Latrans) In The Southeastern United States, Cady Etheredge

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Recent coyote (Canis latrans ) colonization of the southeastern United States has prompted speculation on the top-down effects of a new top predator on systems which have gone without a strong predator presence since the extirpation of the red wolf (Canis rufus ). This dissertation reports on the results of a series of investigations of the potential impact of coyotes on raccoons (Procyon lotor ) and other management issues related to coyotes in the Southeast. Chapters 1-3 present indirect field tests of the Mesopredator Release Hypothesis. Chapter 4 presents an overview of the current knowledge of the …

Factors Affecting The Surface-Mediated Reduction Of Plutonium In The Presence Of Pure Mineral Phases, Amy Hixon

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The overall objective of the research is to investigate the mechanistic and kinetic aspects of the surface-mediated reduction of plutonium. The first chapter is a critical review of plutonium sorption to pure mineral phases. The objective is to study if and how the mechanisms by which plutonium interacts with mineral surfaces are connected to mechanisms for the surface-mediated reduction of plutonium. The main conclusion of the review is that advanced spectroscopy, microscopy, and molecular modeling are needed to fully understand not only the surface structure of pure mineral phases, but also the coordination and bonding environment of plutonium surface complexes. …

Extreme Value Theory In Periodic Time Series, Zhiyun Gong

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Extreme data points are important in environmental, financial, and insurance settings. In this work, we consider two topics on extremes from environmental data. Many environmental time series have a seasonal structure. The first part presents an approach to identify the rare events of such series based on time series residuals. Here, periodic autoregressive moving-average models are applied to describe the series. The methods justify the application of classical peaks over threshold methods to estimated versions of the one-step-ahead prediction errors of the series. Such methods enable the seasonal means, variances, and autocorrelations of the series to be taken into account. …

Engineering Specifications And Mathematics For Verified Software, Hampton Smith

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Developing a verifying compiler---a compiler that proves that components are correct with respect to their specifications---is a grand challenge for the computing community. The prevailing view of the software engineering community is that this problem is necessarily difficult because, to-date, the resultant verification conditions necessary to prove software correctness have required powerful automated provers and deep mathematical insight to dispatch. This seems counter-intuitive, however, since human programmers only rarely resort to deep mathematics to assure themselves that their code works.
In this work, we show that well-specified and well-engineered software supported by a flexible, extensible mathematical system can yield verification …

Mathematical Optimization For Engineering Design Problems, Brian Dandurand

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Applications in engineering design and the material sciences motivate the development of optimization theory in a manner that additionally draws from other branches of mathematics including the functional, complex, and numerical analyses.
The first contribution, motivated by an automotive design application, extends multiobjective optimization theory under the assumption that the problem information is not available in its entirety to a single decision maker as traditionally assumed in the multiobjective optimization literature. Rather, the problem information and the design control are distributed among different decision makers. This requirement appears in the design of an automotive system whose subsystem components themselves correspond …

Count Time Series And Discrete Renewal Processes, James Livsey

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Most data collected over time has some degree of periodicity (i.e. seasonally varying
traits). Climate, stock prices, football season, energy consumption, wildlife sightings, and
holiday sales all have cyclical patterns. It should come as no surprise that models that
incorporate periodicity are paramount in the study of time series.
The following work devises time series models for counts (integer-values) that are periodic
and stationary. Foundational work is rst done in constructing a stationary periodic
discrete renewal process (SPDRP). The dynamics of the SPDRP are mathematically interesting
and have many modeling applications, expositions largely unexplored here. This work
develops a SPDRP …

Multi-Scale Defect Engineering And Interface Modifications For Enhancement Of Thermoelectric Properties In Nanostructured Bulk Materials, Pooja Puneet

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Among various static energy conversion technologies, the thermoelectric (TE) energy conversion has gained the considerable interest due to its reliability and ability to directly convert waste heat into electricity. In TE conversion technology, physical properties such as thermopower (α), electrical (σ) and thermal conductivity (κ) are exploited simultaneously to convert waste heat into electricity. The efficiency of such conversion depends upon various factors such as temperature, figure of merit (ZT= α2σ/ κ) etc. An inherent coupling among α, σ and κ limits ZT and thereby constrains one in achieving high efficiency. Many efforts have been carried out in decoupling TE …

Long-Term Bald Eagle Monitoring: Assessing Emerging Risks To The Great Lakes Ecosystem By Evaluating Impacts To Tertiary Predators, Latice Fuentes

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Data from the Michigan Bald Eagle Biomonitoring Project (MBEBP) was used to provide ecological evaluations amidst concerns of emerging contaminants and environmental change. Samples and measurements were collected throughout the state of Michigan from 1998-2012. Nestling breast feathers and biometric measurements were used in analytical and statistical analyses which provided a broad assessment of the Great Lakes ecosystem and its resident bald eagles. Bald eagle nestling feathers were taken from Michigan breeding areas, and used to evaluate spatial and temporal trends of mercury (Hg). Overall, remediation has positively affected the Great Lakes region. However, Michigan's Upper Peninsula and Lake Superior …

Advancements In Finite Element Methods For Newtonian And Non-Newtonian Flows, Keith Galvin

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This dissertation studies two important problems in the mathematics of computational fluid dynamics. The first problem concerns the accurate and efficient simulation of incompressible, viscous Newtonian flows, described by the Navier-Stokes equations. A direct numerical simulation of these types of flows is, in most cases, not computationally feasible. Hence, the first half of this work studies two separate types of models designed to more accurately and efficient simulate these flows. The second half focuses on the defective boundary problem for non-Newtonian flows. Non-Newtonian flows are generally governed by more complex modeling equations, and the lack of standard Dirichlet or Neumann …

On The Cuspidality Of Maass-Gritsenko And Mixed Level Lifts, Dania Zantout

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your words

Bond-Centric Modifications To Bond-Order Potentials And Ab-Initio Evaluation Of Nanostructured Materials Properties, Jaewoong Hur

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An improvement to the AIREBO potential for hydrocarbons is presented in which contribu-tions to the bond order are determined by the local bonding environment around the bond, rather than the average of the environments around the two constituent atoms. This bond-centric approach decreases the errors by ∼80% in the fullerene-type systems for which the original approach leads to the most severe errors. With the newly developed and parameterized method, energy errors are less than 0.7eV for a collection of hydrocarbon molecules not used in the fitting. This modified AIREBO potential is expected to be more useful not only for the …

Hydrothermal Chemistry, Crystal Structures, And Spectroscopy Of Novel Fluorides And Borates, Christopher Underwood

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This dissertation is a two-part manuscript highlighting the utilities of the hydrothermal method for exploring phase space, then extending that to the targeted growth of potentially useful materials. Chapters 3 - 5 discuss the synthesis of Group 4 fluorides and oxyfluorides. The study of this class of compounds in regards to their single crystal structures is a rich, but neglected area. Among the Group 4 metals, compounds based on Zr and Ti have been extensively studied, while those based on Th and Hf are sparsely reported and those based on Ce(IV) are nearly completely neglected. Using the hydrothermal method, many …

Gesture-Based Robot Path Shaping, Paul Yanik

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For many individuals, aging is frequently associated with diminished mobility and dexterity. Such decreases may be accompanied by a loss of independence, increased burden to caregivers, or institutionalization. It is foreseen that the ability to retain independence and quality of life as one ages will increasingly depend on environmental sensing and robotics which facilitate aging in place. The development of ubiquitous sensing strategies in the home underpins the promise of adaptive services, assistive robotics, and architectural design which would support a person's ability to live independently as they age. Instrumentation (sensors and processing) which is capable of recognizing the actions …

Hydrothermal Crystal Growth Of Metal Borates For Optical Applications, Carla Heyward

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Crystals are the heart of the development of advance technology. Their existence is the essential foundation in the electronic field and without it there would be little to no progress in a variety of industries including the military, medical, and technology fields. The discovery of a variety of new materials with unique properties has contributed significantly to the rapidly advancing solid state laser field. Progress in the crystal growth methods has allowed the growth of crystals once plagued by difficulties as well as the growth of materials that generate coherent light in spectral regions where efficient laser sources are unavailable. …

In Silico Modeling The Effect Of Single Point Mutations And Rescuing The Effect By Small Molecules Binding, Zhe Zhang

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Single-point mutation in genome, for example, single-nucleotide polymorphism (SNP) or rare genetic mutation, is the change of a single nucleotide for another in the genome sequence. Some of them will result in an amino acid substitution in the corresponding protein sequence (missense mutations); others will not. This investigation focuses on genetic mutations resulting in a change in the amino acid sequence of the corresponding protein. This choice is motivated by the fact that missense mutations are frequently found to affect the native function of proteins by altering their structure, interaction and other properties and cause diseases. A particular disease is …

Synthesis And Characterization Of Chromophores And Semiconducting Polymers Incorporating A 1,4-Fluorenylene Scaffold, Brynna Laughlin

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Research on conjugated chromophores and polymers has been a lucrative and highly active area for over a quarter-century. These pursuits have been driven by the unique properties of conjugated systems that allow their application in myriad fields including photonics (e.g. non-linear optics), and especially optoelectronics (e.g. organic light emitting diodes (OLEDs) and photovoltaic (PV) cells). Despite the years of dedicated research, there is still much work to be done in developing better materials for these types of applications. The full range of available molecular architecture and functionalization that are yet to be explored is still an untapped well of research. …

Thermoelectric Study Of Insb Secondary Phase Based Nano Composite Materials, Song Zhu

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In the past several decades there has been an intensive study in the field of thermoelectric study that is basically materials driven. As the simplest technology applicable in direct heat-electricity energy conversion, thermoelectricity utilizes the Seebeck effect to generate electricity from heat or conversely achieve the solid-state cooling via the Peltier effect. With many technical merits, thermoelectric devices can be used as spot-size generators or distributed refrigerators, however, their applications are restricted by the energy conversion efficiency, which is mainly determined by the figure of merit ZT of the thermoelectric materials that these devices are made of.
A higher ZT …

Adaptation Of Regional Representative Soil Project And Soil Judging For Cameroon, Celestine Che

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Representative regional soils have agricultural, cultural, economic, environmental, and historical importance to Cameroon. Twenty seven regional representative soils have been identified in Cameroon. A set of laboratory exercises, assignments and exam questions have been developed utilizing the Regional Representative Soil Project (RRSP) that gives students an opportunity to practice interpretation of soil series descriptions, taxonomic classes, soil forming factors, and soil physical and chemical properties. The RRSP can be further enhanced and complemented with Soil Judging. Conventional soil judging as practiced in the United States has been adapted for Cameroon by a graduate student from that country using an undergraduate-level …

Attaining Sustainable Behavior Among Non-Environmentally-Motivated Individuals: A Formative Experiment, Brooklynn Wynveen

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Experts agree that overconsumption is a major problem in Western culture today, particularly in the United States. Thus, it is important to promote sustainable behavior among the general public. And yet, existing educational programming geared toward promoting such behavior changes remains appealing largely to environmentally-motivated audiences, as opposed to individuals with alternative (i.e., social and economic) motivations. In response to this discrepancy, I conducted a formative experiment with the goals of: 1) fostering participation among non-environmentally-motivated individuals in sustainable living educational programming; and 2) obtaining behavior change commitments, in the direction of more sustainable lifestyles, from those participants.
As part …

Robust And Efficient Regression, Qi Zheng

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This dissertation aims to address two problems in regression
analysis. One problem is the model selection and robust parameter estimation in high dimensional linear regressions. The other is concerning developing a robust and efficient estimator in nonparametric regressions.
In Chapter 1, we introduce the robust and efficient regression analysis, discuss those two interesting problems and our motivations, and present several exciting results.
We propose a novel robust penalized method for high dimensional linear regression in Chapter 2. Asymptotic properties are established and a data-driven procedure is developed to select adaptive penalties. We show it is the very first estimator to …