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Brigham Young University

2019

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Articles 1 - 30 of 112

Full-Text Articles in Physical Sciences and Mathematics

Automatic Detection And Prevention Of Fake Key Attacks In Signal, Tarun Kumar Yadav Dec 2019

Automatic Detection And Prevention Of Fake Key Attacks In Signal, Tarun Kumar Yadav

Theses and Dissertations

The Signal protocol provides end-to-end encryption for billions of users in popular instant messaging applications like WhatsApp, Facebook Messenger, and Google Allo. The protocol relies on an app-specific central server to distribute public keys and relay encrypted messages between the users. Signal prevents passive attacks. However, it is vulnerable to some active attacks due to its reliance on a trusted key server. A malicious key server can distribute fake keys to users to perform man-in-the-middle or impersonation attacks. Signal applications support an authentication ceremony to detect these active attacks. However, this places an undue burden on the users to manually …

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Cell Velocity Is Asymptotically Independent Of Force: A Differential Equation Model With Random Switching., J. C. Dallon, Emily J. Evans, Christopher P. Grant, William V. Smith Dec 2019

Cell Velocity Is Asymptotically Independent Of Force: A Differential Equation Model With Random Switching., J. C. Dallon, Emily J. Evans, Christopher P. Grant, William V. Smith

Faculty Publications

Numerical simulations suggest that average velocity of a biological cell depends largely on attachment dynamics and less on the forces exerted by the cell. We determine the relationship between two models of cell motion, one based on finite spring constants modeling attachment properties (a randomly switched differential equation) and a limiting case (a centroid model-a generalized random walk) where spring constants are infinite. We prove the main result of this paper, the Expected Velocity Relationship theorem. This result shows that the expected value of the difference between cell locations in the differential equation model at the initial time and at …

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Controller Design For Coordinated Encirclement Of Moving Targets, Puneet Jain Dec 2019

Controller Design For Coordinated Encirclement Of Moving Targets, Puneet Jain

Theses and Dissertations

This thesis presents controllers that use relative range and bearing measurements to steer unmanned aerial vehicles (UAVs) to circular trajectories around stationary, constantly moving and constantly accelerating targets. The range and bearing to the target, along with their derivaties are estimated. These, along with the estimated local heading of the UAVs, are used in the control law, and to estimate the velocity of the target. In this work, six controllers are presented. The controller for a stationary target is derived using Lyapunov's direct method, and feedback linearization is used for the constant velocity and accelerating targets. A new controller is …

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Inclusion Of Kinetic Proteomics In Multi-Omics Methods To Analyze Calorie Restriction Effects On Aging, Richard Hajime Carson Dec 2019

Inclusion Of Kinetic Proteomics In Multi-Omics Methods To Analyze Calorie Restriction Effects On Aging, Richard Hajime Carson

Theses and Dissertations

One of the greatest risk factors for disease is advanced age. As the human lifespan has increased, so too have the burdens of caring for an increasingly older population suffering from rising rates of cardiovascular disease, kidney disease, diabetes, and dementia. The need for improving medical technology and developing new therapies for age-related diseases is manifest. Yet our understanding of the processes of aging and how to attenuate the effects of aging remains incomplete. Various studies have established calorie restriction as a robust method for extending lifespan in laboratory organisms; however the mechanism is a topic of much debate. Advancing …

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Exploring The Relationship Between Vocabulary Scaling And Algorithmic Performance In Text Classification For Large Datasets, Wilson Murray Fearn Dec 2019

Exploring The Relationship Between Vocabulary Scaling And Algorithmic Performance In Text Classification For Large Datasets, Wilson Murray Fearn

Theses and Dissertations

Text analysis is a significant branch of natural language processing, and includes manydifferent sub-fields such as topic modeling, document classification, and sentiment analysis.Unsurprisingly, those who do text analysis are concerned with the runtime of their algorithmsSome of these algorithms have runtimes that depend jointly on the size of the corpus beinganalyzed, as well as the size of that corpus's vocabulary. Trivially, a user may reduce theamount of data they feed into their model to speed it up, but we assume that users will behesitant to do this as more data tends to lead to better model quality. On the other …

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Coordinated Persistent Homology And An Application To Seismology, Nickolas Brenten Callor Dec 2019

Coordinated Persistent Homology And An Application To Seismology, Nickolas Brenten Callor

Theses and Dissertations

The theory of persistent homology (PH), introduced by Edelsbrunner, Letscher, and Zomorodian in [1], provides a framework for extracting topological information from experimental data. This framework was then expanded by Carlsson and Zomorodian in [2] to allow for multiple parameters of analysis with the theory of multidimensional persistent homology (MPH). This particular generalization is considerably more difficult to compute and to apply than its predecessor. We introduce an intermediate theory, coordinated persistent homology (CPH), that allows for multiple parameters while still preserving the clarity and coherence of PH. In addition to introducing the basic theory, we provide a polynomial time …

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An Equivalence Of Shape And Deck Groups; Further Classification Of Sharkovskii Groups, Tyler Willes Hills Dec 2019

An Equivalence Of Shape And Deck Groups; Further Classification Of Sharkovskii Groups, Tyler Willes Hills

Theses and Dissertations

In part one we show that for a compact, metric, locally path-connected topological space X, the shape group of X - as defined in Foundations of Shape Theory by Mardesic and Segal - is isomorphic to the inverse limit of discrete homotopy groups introduced by Conrad Plaut and Valera Berestovskii. We begin by providing the reader preliminary definitions of the fundamental group of a topological space, inverse systems and inverse limits, the Shape Category, discrete homotopy groups, and culminate by providing an isomorphism of the shape and deck groups for peano continua. In part two we develop work and provide …

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Materials Prediction Using High-Throughput And Machine Learning Techniques, Chandramouli Nyshadham Dec 2019

Materials Prediction Using High-Throughput And Machine Learning Techniques, Chandramouli Nyshadham

Theses and Dissertations

Predicting new materials through virtually screening a large number of hypothetical materials using supercomputers has enabled materials discovery at an accelerated pace. However, the innumerable number of possible hypothetical materials necessitates the development of faster computational methods for speedier screening of materials reducing the time of discovery. In this thesis, I aim to understand and apply two computational methods for materials prediction. The first method deals with a computational high-throughput study of superalloys. Superalloys are materials which exhibit high-temperature strength. A combinatorial high-throughput search across 2224 ternary alloy systems revealed 102 potential superalloys of which 37 are brand new, all …

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Aspects Of Engaging Problem Contexts From Students' Perspectives, Tamara Kay Stark Dec 2019

Aspects Of Engaging Problem Contexts From Students' Perspectives, Tamara Kay Stark

Theses and Dissertations

Aspects of Engaging Problem Contexts From Students' PerspectivesTamara Kay Gandolph StarkDepartment of Mathematics Education, BYUMaster of ArtsToo many students have negative feelings towards mathematics which is causing them to disengage in their classrooms. This has led to student under-achievement. This study attempts to better understand how teachers can help students to reengage with mathematics by using more engaging contexts to develop mathematical content. The study began with the characteristics realistic, worthwhile, enjoyable or motivating as a framework for posing engaging problem contexts, which were synthesized from the current research literature. As students discussed what made contexts engaging, my understanding of …

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Depositional Analysis Of A Holocene Carbonate Strand Plain Using High Resolution Gpr, Sediment Analysis, And C-14 Dating, Kaleb Robert Markert Dec 2019

Depositional Analysis Of A Holocene Carbonate Strand Plain Using High Resolution Gpr, Sediment Analysis, And C-14 Dating, Kaleb Robert Markert

Theses and Dissertations

Understanding modern carbonate depositional systems gives valuable insights into the interpretation of ancient carbonate systems. Ancient carbonate strand plains have the potential to act as productive hydrocarbon reservoirs because of their relatively high porosity. Unfortunately, they are difficult to identify in the rock record because of the lack of work done on modern analogues. San Salvador Island in the Bahamas hosts a well-exposed and easily accessible Holocene strand plain, ideal as a modern analogue. Sandy Hook, located on the southeast part of the island, consists of approximately 35 ridge-swale features that show signs of four distinct zones of deposition. In …

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Almost Homeomorphisms And Inscrutability, Michael Steven Andersen Dec 2019

Almost Homeomorphisms And Inscrutability, Michael Steven Andersen

Theses and Dissertations

“Homeomorphic'' is the standard equivalence relation in topology. To a topologist, spaces which are homeomorphic to each other aren't merely similar to each other, they are the same space. We study a class of functions which are homeomorphic at “most'' of the points of their domains and codomains, but which may fail to satisfy some of the properties required to be a homeomorphism at a “small'' portion of the points of these spaces. Such functions we call “almost homeomorphisms.'' One of the nice properties of almost homeomorphisms is the preservation of almost open sets, i.e. sets which are “close'' to …

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Electrical Conductivity Of The Aluminum Oxide Diffusion Barrier Following Catalytic Carbon Nanotube Growth, Berg Daniel Dodson Dec 2019

Electrical Conductivity Of The Aluminum Oxide Diffusion Barrier Following Catalytic Carbon Nanotube Growth, Berg Daniel Dodson

Theses and Dissertations

Carbon nanotube templated microfabrication (CNT-M) is a method that allows high-aspect ratio structures to be made for microelectromechanical systems (MEMS) devices. One concern when making monolithic electrical devices using CNT-M is that the aluminum oxide diffusion barrier will create too large of a resistance in the device. However, in developing CNT based MEMS devices, it has been observed that an electrical DC current is capable of transport from a conductive substrate, across the aluminum oxide, and through to the CNT structure grown on top of it. This thesis attempts to determine the mechanisms responsible for current being able to cross …

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Recommending Games To Adults With Autism Spectrum Disorder(Asd) For Skill Enhancement Using Minecraft, Alisha Banskota Nov 2019

Recommending Games To Adults With Autism Spectrum Disorder(Asd) For Skill Enhancement Using Minecraft, Alisha Banskota

Theses and Dissertations

Autism spectrum disorder (ASD) is a long-standing mental condition characterized by hindered mental growth and development. In 2018, 168 out of 10,000 children are said to be affected with Autism in the USA. As these children move to adulthood, they have difficulty in communicating with others, expressing themselves, maintaining eye contact, developing a well-functioning motor skill or sensory sensitivity, and paying attention for longer period. Some of these abnormalities, however, can be gradually improved if they are treated appropriately during their adulthood. Studies have shown that people with ASD can enhance their social-interactive skills by playing video games. During the …

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Average Speech Directivity, Samuel D. Bellows, Claire M. Pincock, Jennifer K. Whiting, Timothy W. Leishman Nov 2019

Average Speech Directivity, Samuel D. Bellows, Claire M. Pincock, Jennifer K. Whiting, Timothy W. Leishman

Directivity

Speech directivity describes the angular dependence of acoustic radiation from a talker’s mouth and nostrils and diffraction about his or her body and chair (if seated). It is an essential physical aspect of communication affecting sounds and signals in acoustical environments, audio, and telecommunication systems. Because high-resolution, spherically comprehensive measurements of live, phonetically balanced speech have been unavailable in the past, the authors have undertaken research to produce and share such data for simulations of acoustical environments, optimizations of microphone placements, speech studies, and other applications. The measurements included three male and three female talkers who repeated phonetically balanced passages …

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Light-Field Style Transfer, David Marvin Hart Nov 2019

Light-Field Style Transfer, David Marvin Hart

Theses and Dissertations

For many years, light fields have been a unique way of capturing a scene. By using a particular set of optics, a light field camera is able to, in a single moment, take images of the same scene from multiple perspectives. These perspectives can be used to calculate the scene geometry and allow for effects not possible with standard photographs, such as refocus and the creation of novel views.Neural style transfer is the process of training a neural network to render photographs in the style of a particular painting or piece of art. This is a simple process for a …

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Hydrological And Paleoclimate Analysis Of A Pinyon-Juniper And Fen-Dominated Watershed On The Windy Ridge Mega-Landslide, Joel Frederick Barker Nov 2019

Hydrological And Paleoclimate Analysis Of A Pinyon-Juniper And Fen-Dominated Watershed On The Windy Ridge Mega-Landslide, Joel Frederick Barker

Theses and Dissertations

Water BudgetThis chapter documents the hydrologic analysis of a watershed within the Windy Ridge mega-landslide of Central Utah to (1) create a water budget and (2) place a quantitative limit on the magnitude of climatic changes documented by Shurtliff et al. (2017) and Hudson et al. (2019). (1) A water budget was calculated over the last four years using instrumentation and weather stations both within and surrounding the watershed, In terms of precipitation input, 85% is released by the evapotranspiration of the Pinyon-Juniper forest, 4% discharges as surface water from the base of the watershed, and 11 % infiltrates the …

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Bifunctional Helical Peptide Catalysts For Enzyme-Like Reactivity And Selectivity And Selective Stapling Of Natural Amino Acid Residues With Hydrophilic Squaric Acid Derivatives, Michael James Kinghorn Oct 2019

Bifunctional Helical Peptide Catalysts For Enzyme-Like Reactivity And Selectivity And Selective Stapling Of Natural Amino Acid Residues With Hydrophilic Squaric Acid Derivatives, Michael James Kinghorn

Theses and Dissertations

Peptide secondary structure provides an exceptional scaffold on which to design highly reactive and selective enzyme-like catalysts. This work describes the rational design and synthesis of a suite of helical peptide catalysts that are capable of achieving proximity-induced rate enhancement in Diels-Alder cycloadditions and indole alkylations. Microwave assisted synthesis of resin-supported polypeptides enables incorporation of non-natural amino acid residues that induce helicity (Aib) or provide functional handles on which organic catalytic residues can be attached. These small peptide catalysts exhibit binding-driven selectivity rather than relying on the inherent reactivity of substrates, which allows access to products that are not obtainable …

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Exploration Of Sputtered Thin Films—E.G., In Sample Preparation And Material Characterization, Tuhin Roychowdhury Oct 2019

Exploration Of Sputtered Thin Films—E.G., In Sample Preparation And Material Characterization, Tuhin Roychowdhury

Theses and Dissertations

My dissertation focuses on (i) the development sputtered films for solid phase microextraction (SPME) and (ii) the comprehensive characterization of materials using a suite of analytical techniques. Chapter 1 reviews the basics of SPME. This chapter also contains (i) a discussion of various sputtering techniques, (ii) a discussion of two techniques I focused on most of my work: spectroscopic ellipsometry (SE) and X-ray photoelectron spectroscopy (XPS). Chapter 2 focuses the major part of my work, which is to prepare new solid phases/adsorbents for SPME via silicon sputtering followed by thermal deposition of a polymer, polydimethylsiloxane (PDMS). PDMS was deposited by …

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Making Sense Of The Equal Sign In Middle School Mathematics, Chelsea Lynn Dickson Oct 2019

Making Sense Of The Equal Sign In Middle School Mathematics, Chelsea Lynn Dickson

Theses and Dissertations

One of the main reasons that students struggle as they transition from arithmetic to algebra in the middle grades is that they fail to develop the appropriate understanding of the equal sign. Previous research has suggested that students need to move past an operational understanding and develop a relational understanding of the equal sign in order to work with algebraic equations successfully. Other research has suggested that the way that we interpret and utilize the equal sign is based on three main factors: multiple meanings of the equal sign, equation types, and structural conventions. This study extends both areas of …

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Preparation And Detailed X-Ray Photoelectron Spectroscopy And Spectroscopic Ellipsometryanalysis Of Ultrathin Protective Coatings, Brian Ivins Johnson Oct 2019

Preparation And Detailed X-Ray Photoelectron Spectroscopy And Spectroscopic Ellipsometryanalysis Of Ultrathin Protective Coatings, Brian Ivins Johnson

Theses and Dissertations

Ultra-thin films (UTFs) are important in many applications, seen in the semiconductor industry, in chromatography, in sensing, in microfluidics, in aerospace, and in robotics. They also protect materials from corrosion, change surface energies, limit water intrusion into materials, allow material self-cleaning and self-healing, provide scratch resistance, and impart other specific chemical properties. In many cases, UTFs drastically alter surface properties and therefore their applications. It is imperative that proper and consistent characterization be performed on coatings to confirm and understand their desired properties. In Chapter two, Al oxidation under MgF2 protective layers is studied using real time X-ray photoelectron spectroscopy …

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Resolving The Privacy Paradox: Bridging The Behavioral Intention Gap With Risk Communication Theory, Justin Chun Wah Wu Sep 2019

Resolving The Privacy Paradox: Bridging The Behavioral Intention Gap With Risk Communication Theory, Justin Chun Wah Wu

Theses and Dissertations

The advent of the Internet has led to vastly increased levels of data accessibility to both users and would-be attackers. The privacy paradox is an established phenomenon wherein users express concern about resultant security and privacy threats to their data, but nevertheless fail to enact the host of protective measures that have steadily become available. The precise nature of this phenomenon, however, is not a settled matter. Fortunately, risk communication theory, a discipline devoted to understanding the factors involved in risk-oriented decision-making and founded in years of empirical research in public health and disaster awareness domains, presents an opportunity to …

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Laying A Foundation For Computing In Outdoor Recreation, Zann Benjamin Anderson Sep 2019

Laying A Foundation For Computing In Outdoor Recreation, Zann Benjamin Anderson

Theses and Dissertations

Mobile computing allows individuals to bring computing with them into the outdoors. This creates a new situation in which individuals can stay connected even when trying to "get away from it all." Questions arise from this juxtaposition regarding whether the inclusion of computing in these activities is a positive or a negative. Evidence exists supporting both conclusions. We posit that computing can contribute positively to outdoor recreation without distracting. This dissertation details work undertaken in two phases which explores how computing can accomplish this goal. Phase 1 explored how individuals are already using computing technology in hiking, and culminated with …

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Dynamic Coalescence As A Mathematical Model Of Leadership And Empirical Evidence Of The Value Of Strategic Sacrifice, Jacob D. Valentine Sep 2019

Dynamic Coalescence As A Mathematical Model Of Leadership And Empirical Evidence Of The Value Of Strategic Sacrifice, Jacob D. Valentine

Undergraduate Honors Theses

The topic of leadership belongs to a rich literature that is deep in historical documentation and broad by the many disciplines that have attempted to understand it. However, the contributions of quantitative theorists are scarce, which has resulted in theories of leadership that are primarily qualitative and often subjective. This paper begins building a bridge between the existing scholarship and a more quantitative approach to the study of leadership by rigorously defining leadership as a strategy of interpersonal investment and presenting a mathematical model of this leadership theory. This model provides a theoretical foundation to explain team dynamics, to study …

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The Application Of Synthetic Signals For Ecg Beat Classification, Elliot Morgan Brown Sep 2019

The Application Of Synthetic Signals For Ecg Beat Classification, Elliot Morgan Brown

Theses and Dissertations

A brief overview of electrocardiogram (ECG) properties and the characteristics of various cardiac conditions is given. Two different models are used to generate synthetic ECG signals. Domain knowledge is used to create synthetic examples of 16 different heart beat types with these models. Other techniques for synthesizing ECG signals are explored. Various machine learning models with different combinations of real and synthetic data are used to classify individual heart beats. The performance of the different methods and models are compared, and synthetic data is shown to be useful in beat classification.

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Semantically Aligned Sentence-Level Embeddings For Agent Autonomy And Natural Language Understanding, Nancy Ellen Fulda Aug 2019

Semantically Aligned Sentence-Level Embeddings For Agent Autonomy And Natural Language Understanding, Nancy Ellen Fulda

Theses and Dissertations

Many applications of neural linguistic models rely on their use as pre-trained features for downstream tasks such as dialog modeling, machine translation, and question answering. This work presents an alternate paradigm: Rather than treating linguistic embeddings as input features, we treat them as common sense knowledge repositories that can be queried using simple mathematical operations within the embedding space, without the need for additional training. Because current state-of-the-art embedding models were not optimized for this purpose, this work presents a novel embedding model designed and trained specifically for the purpose of "reasoning in the linguistic domain".Our model jointly represents single …

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Dynamical Compact Objects In Numerical Relativity, Hyun Lim Aug 2019

Dynamical Compact Objects In Numerical Relativity, Hyun Lim

Theses and Dissertations

The work of this dissertation will study various aspects of the dynamics of compact objects using numerical simulations.We consider BH dynamics within two modified or alternative theories of gravity. Within a family of Einstein-Maxwell-Dilaton-Axion theories, we find that the GW waveforms from binary black hole (BBH) mergers differ from the standard GW waveform prediction of GR for especially large axion values. For more astrophysically realistic (i.e. smaller) values, the differences become negligible and undetectable. Weestablish the existence of a well-posed initial value problem for a second alternative theory fo gravity (quadratic gravity) and demonstrate in spherical symmetry that a linear …

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Locations Of Real Zeros Of Newforms Of Higher Levels, Hankun Ko Aug 2019

Locations Of Real Zeros Of Newforms Of Higher Levels, Hankun Ko

Theses and Dissertations

This dissertation is concerned with the zeros of holomorphic Hecke cusp forms in the space of newforms. We estimate a lower bound for the number of zeros on the imaginary axis and on the vertical line R(z)=1/2 in the upper half plane, both of which are outside the unit circle centered at the origin, and we denote these by δ1 and δ2 respectively. Ghosh and Sarnak call those zeros that lie on the rays 'real' including the arc z=exp (iθ), π/3 ≤ θ ≤ π/2, and they showed that a lower bound for the zeros on those geodesic lines is …

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“Don’T Say Gay. We Say Dumb Or Stupid”: Queering Prospectivemathematics Teachers’ Discussions, Amy Saunders Ross Aug 2019

“Don’T Say Gay. We Say Dumb Or Stupid”: Queering Prospectivemathematics Teachers’ Discussions, Amy Saunders Ross

Theses and Dissertations

Many prospective teachers make assumptions about their students before they actually begin teaching. Many of these assumptions can be rooted specifically in students’ races, cultures, classes, religions, genders, and sexual orientations. In order for prospective mathematics teachers to challenge these biases, some mathematics teacher educators have provided tasks to support these prospective teachers in becoming aware of their own biases. I chose to analyze a group of five prospective mathematics teachers discussing topics of teaching for social justice to examine more closely the kinds of biases they carry, and more specifically, how those biases came about in their conversations. My …

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A Matched Payout Model For Investment, Consumption, And Insurance With A Risky Annuity Income, Joseph Allen Adams Aug 2019

A Matched Payout Model For Investment, Consumption, And Insurance With A Risky Annuity Income, Joseph Allen Adams

Theses and Dissertations

We introduce a new insurance instrument allowing retirees to hedge against risk of mortality and risk of default. At retirement, the retiree is allowed to purchase an annuity that provides a defaultable income stream over his lifetime. The time of mortality and time of default are both uncertain, but are accompanied by determined hazard rates. The retiree will make consumption and investment choices throughout his lifetime, which have certain restrictions: the retiree can never enter a bankruptcy state (negative total wealth), and the investment choices are made in a risk-free financial instrument (such as a treasury bill or bond) and …

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Preparation, Functionalization, And/Or Characterization By X-Ray Photoelectron Spectroscopy Of Carbon Surfaces For Biosensors And Other Materials, Varun Jain Aug 2019

Preparation, Functionalization, And/Or Characterization By X-Ray Photoelectron Spectroscopy Of Carbon Surfaces For Biosensors And Other Materials, Varun Jain

Theses and Dissertations

My dissertation is primarily divided into two parts. The first deals with the preparation, functionalization, and characterization of carbon surfaces prepared by direct current magnetron sputtering (DCMS) and high power impulse magnetron sputtering (HiPIMS) as substrates for bioarrays. Part two discusses applications of XPS peak fitting in surface chemical analysis. Chapter 1, the introduction, includes (i) a discussion of the construction of bioarrays and the preparation of sputtered surfaces, e.g., by DCMS and HiPIMS, and also functionalization (bioconjugate) chemistry with special emphasis on the importance of covalent functionalization of surfaces, and (ii) a discussion of the surface characterization techniques and …

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