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All Dissertations

2014

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Full-Text Articles in Physical Sciences and Mathematics

Empowering Citizens In A Global Era: A Grounded Theory Study Of Community Gardens, Anita Tam Dec 2014

Empowering Citizens In A Global Era: A Grounded Theory Study Of Community Gardens, Anita Tam

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In our global era, the modern food system can be viewed as consisting of a dominant macro-level corporate food industry, challenged by broad-based meso-level food justice and democracy movements, which are in turn fueled by micro-level community food initiatives. Research has yet to examine the role of community gardens in the context of this complex, multi-level food system. Grounded theory methodology was thus used to explore the deeper meaning of the community gardening experience to participants, in order to better understand the ways in which community gardens may scale up and contribute to democratizing the food system. Analysis of the …

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Chasing Polys: Interdisciplinary Affinity And Its Connection To Physics Identity, Tyler Scott Dec 2014

Chasing Polys: Interdisciplinary Affinity And Its Connection To Physics Identity, Tyler Scott

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This research is based on two motivations that merge by means of the frameworks of interdisciplinary affinity and physics identity. First, a goal of education is to develop interdisciplinary abilities in students' thinking and work. But an often ignored factor is students interests and beliefs about being interdisciplinary. Thus, this work develops and uses a framework called interdisciplinary affinity. It encompasses students interests in making connections across disciplines and their beliefs about their abilities to make those connections. The second motivation of this research is to better understand how to engage more students with physics. Physics identity describes how a …

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Surface Modifications Of Capillary-Channeled Polymer (C-Cp) Fiber Stationary Phases: Improving The Efficiency Of Highly Selective Analyte Separations, Abby Schadock-Hewitt Dec 2014

Surface Modifications Of Capillary-Channeled Polymer (C-Cp) Fiber Stationary Phases: Improving The Efficiency Of Highly Selective Analyte Separations, Abby Schadock-Hewitt

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High performance liquid chromatography (HPLC) is a fundamental methodology for the characterization and purification of macromolecules. Since its development in the 1970's, HPLC has significantly advanced its instrumentation and column technology to become a powerful analytical technique. A considerable amount of research focuses on advancements to the stationary phase, or solid support, on which molecules interact and separate. To overcome limitations of other phases that lead to poor mass transfer, slow speeds, and low efficiency, nonporous and superficially porous phases have been developed. Specifically, fiber based polymer stationary phases show great promise as stationary phases for protein separations. The Marcus …

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Toward Understanding The Thermodynamics And Mechanisms Of Actinide Sorption Reactions, Shanna Estes Dec 2014

Toward Understanding The Thermodynamics And Mechanisms Of Actinide Sorption Reactions, Shanna Estes

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The environmental fate of actinides is greatly influenced by interfacial reactions, including sorption onto solid surfaces. Because changes in the primary hydration sphere of the actinide are expected to greatly influence the thermodynamics (i.e., reaction enthalpy and entropy) of these reactions, examining actinide sorption thermodynamics may provide insight into actinide sorption mechanisms. Additionally, examining actinide sorption thermodynamics may enhance the ability to model or predict these reactions in environmental or engineered systems where variable or elevated temperatures are expected. However, few researchers have studied actinide sorption thermodynamics. Therefore, this research examined the thermodynamics of Eu(III) (a trivalent actinide analog), Th(IV), …

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Efficient And Reliable Simulation, Memory Protection, And Driver Generation In Embedded Network Systems, Jiannan Zhai Dec 2014

Efficient And Reliable Simulation, Memory Protection, And Driver Generation In Embedded Network Systems, Jiannan Zhai

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Embedded systems are widely used, from consumer electronics, to industrial equipment, to spacecraft. With embedded systems becoming more complex, new challenges are presented to application developers. In this dissertation, we focus on three of the most important: (i) Network simulation tools are widely used for sensor network testing and evaluation. Simulation performance affects the efficiency of the application developers who use these tools. The performance of a single host system represents a performance bottleneck for large-scale network simulation. A distributed simulator offering higher performance is needed to support fast, large-scale network simulation. (ii) Single event upsets (SEUs), which occur when …

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Design With Emotion: Improving Web Search Experience For Older Adults, Tamirat Abegaz Dec 2014

Design With Emotion: Improving Web Search Experience For Older Adults, Tamirat Abegaz

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Research indicates that older adults search for information all together about 15% less than younger adults prior to making decisions. Prior research findings associated such behavior mainly with age-related cognitive difficulties. However, recent studies indicate that emotion is linked to influence search decision quality. This research approaches questions about why older adults search less and how this search behavior could be improved. The research is motivated by the broader issues of older users' search behavior, while focusing on the emotional usability of search engine user interfaces. Therefore, this research attempts to accomplish the following three objectives: a) to explore the …

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The Challenges And Opportunities Throughout The Life Cycle Of Landscape-Scale Collaborative Conservation Organizations: Case Studies In The Southern Appalachians And The Northern Rockies Ecosystems, Jennifer Thomsen Dec 2014

The Challenges And Opportunities Throughout The Life Cycle Of Landscape-Scale Collaborative Conservation Organizations: Case Studies In The Southern Appalachians And The Northern Rockies Ecosystems, Jennifer Thomsen

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Currently our natural environment is threatened by climate change, habitat fragmentation, and other transboundary issues. To address these problems, it is thought that conservation organizations and land management agencies should attempt to manage at larger geographic scales and across political boundaries. The Crown Managers Partnership (CMP) and the Southern Appalachian Man and the Biosphere Cooperative (SAMAB) are two such organizations that work at an ecoregional scale to support collaboration among agencies, aboriginal groups, conservationists, scientists, and other stakeholders for the conservation and restoration of the Northern Rocky Mountain and the Southern Appalachian regions in North America. Over the past decades, …

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Majorana Fermions In Chiral Topological Superconductors, Eugen Florin Dumitrescu Dec 2014

Majorana Fermions In Chiral Topological Superconductors, Eugen Florin Dumitrescu

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Majorana fermions were first proposed in the context of high energy physics by Ettore Majorana in 1937, just before his mysterious disappearance. Now, over 70 years later, signatures of condensed matter ana-logues of Majorana fermions are finally appearing in low-dimensional superconductor-based heterostructures. In low-dimensional systems, these order parameter, defect-bound Majorana quasiparticles obey non-Abelian quantum statistics and can therefore be used as the building blocks of a topological quantum computer. In this thesis we will analyze the signatures associated with, and the robustness of, Majorana bound states in a variety of one-dimensional superconducting platforms. Our main result is the finding that …

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Experimental Evidence For Colloid-Facilitated Transport Of Plutonium, Hilary Emerson Dec 2014

Experimental Evidence For Colloid-Facilitated Transport Of Plutonium, Hilary Emerson

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Colloid-facilitated transport of the actinides has been observed previously in the field on the kilometer scale. The objective of this work is to investigate the mechanisms of colloid-facilitated transport with controlled settings and conditions. The experimental work in this dissertation investigates transport of a ternary complex with iron oxide colloids, organic ligands and actinides in the presence of quartz or a natural sandy soil as well as simplified systems building up to the ternary complexes. The first three papers investigate the following: (1) unsaturated transport of iron oxide colloids in a natural sandy soil lysimeter with and without natural organic …

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An Approximation Algorithm For The Stable Marriagae Problem With Ties And Incomplete Lists, Rommel Jalasutram Dec 2014

An Approximation Algorithm For The Stable Marriagae Problem With Ties And Incomplete Lists, Rommel Jalasutram

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Consider the bipartite matching problem with two sets of participants: men (L) and women (R). Each person participating has a strict and complete preference list over participants from the other set. The goal is to pair men and women such that no one can improve their partner by breaking away from the centralized matching scheme. Problems that exhibit this flavor are commonly classified as ordinal matchings. Gale and Shapley showed how to obtain such a matching (otherwise known as a “stable” matching). Generalizations of this model have found relevance in several centralized matching schemes such as the National Residency Matching …

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Earth Abundant Thin Film Technology For Next Generation Photovoltaic Modules, Githin Alapatt Dec 2014

Earth Abundant Thin Film Technology For Next Generation Photovoltaic Modules, Githin Alapatt

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With a cumulative generation capacity of over 100 GW, Photovoltaics (PV) technology is uniquely poised to become increasingly popular in the coming decades. Although, several breakthroughs have propelled PV technology, it accounts for only less than 1% of the energy produced worldwide. This aspect of the PV technology is primarily due to the somewhat high cost per watt, which is dependent on the efficiency of the PV cells as well as the cost of manufacturing and installing them. Currently, the efficiency of the PV conversion process is limited to about 25% for commercial terrestrial cells; improving this efficiency can increase …

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Gender And Ethnicity Classification Using Partial Face In Biometric Applications, Jamie Lyle Dec 2014

Gender And Ethnicity Classification Using Partial Face In Biometric Applications, Jamie Lyle

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As the number of biometric applications increases, the use of non-ideal information such as images which are not strictly controlled, images taken covertly, or images where the main interest is partially occluded, also increases. Face images are a specific example of this. In these non-ideal instances, other information, such as gender and ethnicity, can be determined to narrow the search space and/or improve the recognition results. Some research exists for gender classification using partial-face images, but there is little research involving ethnic classifications on such images. Few datasets have had the ethnic diversity needed and sufficient subjects for each ethnicity …

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Unusually Low Thermal Conductivity In The Argyrodite Ag8gete6 Attributed To Strong Anharmonicity, Dale Hitchcock Dec 2014

Unusually Low Thermal Conductivity In The Argyrodite Ag8gete6 Attributed To Strong Anharmonicity, Dale Hitchcock

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Arguably the main focus of thermoelectric materials research over the last decade has been the reduction of lattice thermal conductivity through nanostructuring. This approach has proved quite effective in many instances, but has several inherent drawbacks including not only the metastability of many of the nanostructures used, but also difficulty decoupling the effects on the thermal properties of materials from the effects on their electrical properties. Some more recent research has focused on reduced thermal conductivity in materials with strong anharmonicity. In these systems anharmonicty in the crystal structure, whose strength can be gauged by the so-called Gruneissen parameter leads …

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Numerical Decoding, Johnson-Lindenstrauss Transforms, And Linear Codes, Yue Mao Dec 2014

Numerical Decoding, Johnson-Lindenstrauss Transforms, And Linear Codes, Yue Mao

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Many computational problems are related to the model y = Ax + e, including compressive sensing, coding theory, dimensionality reduction, etc. The related algorithms are extremely useful in practical applications for high performance computing, for example, digital communications, biological imaging and data streaming, etc. This thesis studies two important problems. One problem is related to efficient decoding for Reed-Solomon codes over complex numbers. In this case, A and y are given, and the goal is to find an efficient stable algorithm to compute x. This is related to magnetic resonance imaging (MRI). The other problem is related to fast algorithms …

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Serious Toys: Teaching Computer Science Concepts To Pre-Collegiate Students, Yvon Feaster Dec 2014

Serious Toys: Teaching Computer Science Concepts To Pre-Collegiate Students, Yvon Feaster

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Advancements in science and engineering have driven innovation in the United States for more than two centuries. The last several decades have brought to the forefront the importance of such innovation to our domestic and global economies. To continue to succeed in this information-based, technologically advanced society, we must ensure that the next generation of students are developing computational thinking skills beyond what was acceptable in past years. Computational thinking represents a collection of structured problem solving skills that cross-cut educational disciplines. There is significant future value in introducing these skills as early as practical in students' academic careers. Over …

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Neutron Study Of Structure And Dynamics Of Rigid Polymers, Naresh Osti Dec 2014

Neutron Study Of Structure And Dynamics Of Rigid Polymers, Naresh Osti

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The structure and the dynamics in two different classes of rigid polymers; ionomers and rigid luminescent polymers, have been investigated predominantly by neutron techniques. Rigidity of the backbones of both polymers affects their properties. For ionomers, it affects transport pathways, therefore, their applications for energy and separation membranes. In luminescent polymers, it determines the conformations of the chains and their electro-optical response. One group of the polymers consists of rigid hydrophobic para-phenylene backbone decorated with pendant phenyl side chains functionalized with sulfonic acid (SPP). The other family of polymers consists of poly para-phenyleneethynylene (PPE) backbone that becomes conjugated upon conformational …

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A Comprehensive Assessment Methodology Based On Life Cycle Analysis For On-Board Photovoltaic Solar Modules In Vehicles, Mahmoud Abdelhamid Dec 2014

A Comprehensive Assessment Methodology Based On Life Cycle Analysis For On-Board Photovoltaic Solar Modules In Vehicles, Mahmoud Abdelhamid

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This dissertation presents a novel comprehensive assessment methodology for using on-board photovoltaic (PV) solar technologies in vehicle applications. A well-to-wheels life cycle analysis based on a unique energy, greenhouse gas (GHG) emission, and economic perspective is carried out in the context of meeting corporate average fuel economy (CAFE) standards through 2025 along with providing an alternative energy path for the purpose of sustainable transportation. The study includes 14 different vehicles, 3 different travel patterns, in 12 U.S. states and 16 nations using 19 different cost analysis scenarios for determining the challenges and benefits of using on-board photovoltaic (PV) solar technologies …

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Development And Evaluation Of Carbon-Based Quantum Dots For Carbon Dioxide Photoconversion, Sushant Sahu Sep 2014

Development And Evaluation Of Carbon-Based Quantum Dots For Carbon Dioxide Photoconversion, Sushant Sahu

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World energy consumption has increasingly grown over the past several decades.Because of its potential in photochemical energy conversion, photocatalysis has been the subject of much recent research. Recently, carbon or graphene-based quantum dots have attracted growing attention in solar energy conversion applications, because of its unique optoelectronic properties, broad-band optical absorption, bright fluorescence emissions, favorable photoinduced electron transfer properties, reliable chemical inertness and stability, cost-effectiveness, and non-toxicity. While nanosized wide band gap semiconductor-based systems were largely at the center of attention in such studies, carbon-based quantum dots have recently emerged as a new class of semiconductor like photoactive materials, due …

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Integrating Visual Mnemonics And Input Feedback With Passphrases To Improve The Usability And Security Of Digital Authentication, Kevin Juang Aug 2014

Integrating Visual Mnemonics And Input Feedback With Passphrases To Improve The Usability And Security Of Digital Authentication, Kevin Juang

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The need for both usable and secure authentication is more pronounced than ever before. Security researchers and professionals will need to have a deep understanding of human factors to address these issues. Due to their ubiquity, recoverability, and low barrier of entry, passwords remain the most common means of digital authentication. However, fundamental human nature dictates that it is exceedingly difficult for people to generate secure passwords on their own. System-generated random passwords can be secure but are often unusable, which is why most passwords are still created by humans. We developed a simple system for automatically generating mnemonic phrases …

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Mechanical Properties Of Low Dimensional Materials, Deepika Saini Aug 2014

Mechanical Properties Of Low Dimensional Materials, Deepika Saini

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Recent advances in low dimensional materials (LDMs) have paved the way for unprecedented technological advancements. The drive to reduce the dimensions of electronics has compelled researchers to devise newer techniques to not only synthesize novel materials, but also tailor their properties. Although micro and nanomaterials have shown phenomenal electronic properties, their mechanical robustness and a thorough understanding of their structure-property relationship are critical for their use in practical applications. However, the challenges in probing these mechanical properties dramatically increase as their dimensions shrink, rendering the commonly used techniques inadequate. This Dissertation focuses on developing techniques for accurate determination of elastic …

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An Experimental Investigation Towards Improvement Of Thermoelectric Properties Of Strontium Titanate Ceramics, Arash Mehdizadeh Dehkordi Aug 2014

An Experimental Investigation Towards Improvement Of Thermoelectric Properties Of Strontium Titanate Ceramics, Arash Mehdizadeh Dehkordi

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The direct energy conversion between heat and electricity based on thermoelectric effects is a topic of long-standing interest in condensed matter materials science. Experimental and theoretical investigations in order to understand the mechanisms involved and to improve the materials properties and conversion efficiency have been ongoing for more than half a century. While significant achievements have been accomplished in improving the properties of conventional heavy element based materials (such as Bi$_2$Te$_3$ and PbTe) as well as the discovery of new materials systems for the close-to-room temperature and intermediate temperatures, high-temperature applications of thermoelectrics is still limited to one materials system, …

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Cnt Welding Through Ar Bombardment Using Airebo Potential And Optimization Of An Extensionded Aireo Potential For F Atom To Simulate Hydrofluorocarbons, Mustafa Kucukkal Aug 2014

Cnt Welding Through Ar Bombardment Using Airebo Potential And Optimization Of An Extensionded Aireo Potential For F Atom To Simulate Hydrofluorocarbons, Mustafa Kucukkal

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ABSTRACT Molecular Dynamics (MD) is an effective method to study diverse systems to gain atomistic level details from the trajectories of particles in the system. MD require a potential which describes the interaction of the particles within the system, which is then used to solve Newton's equation of motion to obtain the trajectories of the particles. For an accurate simulation of a system, an appropriate potential should be used for the MD simulations. The Adaptive Interactive Reactive Empirical Bond Order (AIREBO) potential is a promising potential for MD simulations of systems involving bond breakage or formation [1, 2]. The AIREBO …

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Passivation And Functionalization Of Conjugated Polymer Nanoparticles With Head Group Modified Phospholipids And Proteins, Prakash Kandel Aug 2014

Passivation And Functionalization Of Conjugated Polymer Nanoparticles With Head Group Modified Phospholipids And Proteins, Prakash Kandel

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Conjugated polymer nanoparticles (CPNs) possess important characteristics such as high fluorescence brightness, reasonable photostability, and non-toxicity. These properties allow the use of CPNs in fluorescence based cellular and biological applications including cellular labeling, imaging, biosensing, and single particle tracking. To realize the broad applications of CPNs, it is required that CPNs possess functionality to conjugate a recognition moiety and maintain colloidal stability in biological media. In the following Dissertation, we have prepared functionalized CPNs by surface passivation with head group- functionalized poly (ethylene glycol) lipids and proteins. We studied the colloidal stability of CPNs in biological media and investigated their …

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Grobner Bases: Degree Bounds And Generic Ideals, Juliane Golubinski Capaverde Aug 2014

Grobner Bases: Degree Bounds And Generic Ideals, Juliane Golubinski Capaverde

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In this thesis, we study two problems related to Gröbner basis theory: degree bounds for general ideals and Gröbner bases structure for generic ideals. We start by giving an introduction to Gröbner bases and their basic properties and presenting a recent algorithm by Gao, Volny and Wang. Next, we survey degree bounds for the ideal membership problem, the effective Nullstellensatz, and polynomials in minimal Gröbner bases. We present general upper bounds, and bounds for several classes of special ideals. We provide classical examples showing some of these bounds cannot be improved in general. We present a comprehensive study of a …

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South Atlantic Stream Fish Assemblages: Multi-Scale Structuring Factors, Trait Associations And Channelization, And Responses To Dam Removal, Cathy Marion Aug 2014

South Atlantic Stream Fish Assemblages: Multi-Scale Structuring Factors, Trait Associations And Channelization, And Responses To Dam Removal, Cathy Marion

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South Atlantic coastal plain wadeable streams are unique and understudied freshwater environments that provide crucial habitats for a wide range of aquatic taxa. In Chapter 1, we investigated patterns in fish assemblages across South Carolina's coastal plain, and developed statistical models to identify the dominant multi-scale abiotic environmental factors that influence assemblage structure. Our analyses indicated the presence of four predominant fish assemblages that commonly occur in the coastal plain, which we termed the: 1) fluvial, 2) eastern mudminnow, 3) centrarchid, and 4) non-fluvial assemblages. Natural geographic gradients and instream habitat parameters associated with velocity, channel form, stream size, and …

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Designing For Understanding: Helping Older Adults Understand Over-The-Counter Medication Information, Aqueasha Martin Aug 2014

Designing For Understanding: Helping Older Adults Understand Over-The-Counter Medication Information, Aqueasha Martin

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This research is motivated by some of the challenges faced by the healthcare community in communicating health information to the public and the potential for user-centered technology design to address some of these limitations. Each year, thousands die or are injured due to adverse-drug events due to both prescription and over-the-counter medications. The integration of technology has improved the incidence rate for adverse-drug events due to prescription medications. Similarly, personal health records and other consumer-based health applications have been shown to be beneficial for helping individuals manage their health. Despite this growing body of research, little to no research has …

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Applied Statistics In Environmental Monitoring: Case Studies And Analysis For The Michigan Bald Eagle Biosentinel Program, Katherine Leith Aug 2014

Applied Statistics In Environmental Monitoring: Case Studies And Analysis For The Michigan Bald Eagle Biosentinel Program, Katherine Leith

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The bald eagle (Haliaeetus leucocephalus) is an extensively researched tertiary predator. Its life history and the impact of various stressors on its reproductive outcomes have been documented in many studies, and over many years. Furthermore, the bald eagle population recovery in Michigan has been closely monitored since the 1960s, as it has continued to recover from a contaminant-induced bottleneck. Because of its position at the top of the aquatic food web and the large body of ethological knowledge, the bald eagle has become a sentinel species for the Michigan aquatic ecosystem. In April 1999, the Michigan Department of Environmental Qualtity, …

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Investigation Of Concurrent Energy Harvesting From Ambient Vibrations And Wind, Amin Bibo Aug 2014

Investigation Of Concurrent Energy Harvesting From Ambient Vibrations And Wind, Amin Bibo

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In recent years, many new concepts for micro-power generation have been introduced to harness wasted energy from the environment and maintain low-power electronics including wireless sensors, data transmitters, controllers, and medical implants. Generally, such systems aim to provide a cheap and compact alternative energy source for applications where battery charging or replacement is expensive, time consuming, and/or cumbersome. Within the vast field of micro-power generation, utilizing the piezoelectric effect to generate an electric potential in response to mechanical stimuli has recently flourished as a major thrust area. Based on the nature of the ambient excitation, piezoelectric energy harvesters are divided …

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Understanding Public Perceptions About Beach Nesting Shorebirds And Habitat Management On Cape Cod, Massachusetts, Marla Hamilton Aug 2014

Understanding Public Perceptions About Beach Nesting Shorebirds And Habitat Management On Cape Cod, Massachusetts, Marla Hamilton

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Coastline habitats along the eastern seaboard of North America serve as prime locations for beachfront development and consumptive and non-consumptive recreational opportunities. Many of these areas are also globally important nesting and wintering areas for threatened and endangered shorebirds (primarily species belonging to the order Charadriiformes). Across the span of their hemispheric ranges, shorebirds face significant threats due to increases habitat loss, human disturbance, and illegal hunting practices. With coastline use increasing human-wildlife interactions, positive public input and interaction is needed to mitigate negative consequences to wildlife. Although many techniques have been employed to discourage beach users from practicing recreational …

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Fourth Moment Approximation Of Instrinsic Mode Lifetimes In Solids, Yang Gao Aug 2014

Fourth Moment Approximation Of Instrinsic Mode Lifetimes In Solids, Yang Gao

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A new method (second moment approximation method) of calculating mode lifetimes of materials has been proposed by Dickel and Daw [14, 15]. The method was tested on an anharmonic lattice model, and it shows consistency with results from using traditional method (molecular dy-namics with Green-Kubo [2]) at high temperatures, but deviates at low temperatures. Based on this method, we developed the fourth moment approximation method, and tested it on various models from 1D anharmonic chain to the FCC cube with Lennard-Jones potential. Calculations showed that the fourth moment approximation method provides a fast and reliable scheme to calculate mode lifetimes …

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