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Articles 931 - 960 of 3436

Full-Text Articles in Physical Sciences and Mathematics

Desorption Electrospray Ionization (Desi) Mass Spectrometric Imaging Of Spatially Regulated In Vivo Metabolic Rates, Charlotte Reininger Lewis May 2017

Desorption Electrospray Ionization (Desi) Mass Spectrometric Imaging Of Spatially Regulated In Vivo Metabolic Rates, Charlotte Reininger Lewis

Theses and Dissertations

Desorption electrospray ionization (DESI) is an ambient ionization technique used for mass spectrometric imaging of biological samples. When coupled with isotopic ratio measurements of deuterium-labeled tissues, DESI provides a means of measuring metabolic rates on a spatially resolved basis. In vivo metabolic rates are desired to better understand diseases such as Alzheimer's, Parkinson's, Huntington's, and various forms of cancer that negatively impact metabolic rates within different organs of the human body. Although DESI has been used to image lipids and metabolites of a variety of tissues and other imaging techniques, such as NIMS, have been used to study kinetic turnover …

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Network Reconstruction And Vulnerability Analysis Of Financial Networks, Nathan Scott Woodbury May 2017

Network Reconstruction And Vulnerability Analysis Of Financial Networks, Nathan Scott Woodbury

Theses and Dissertations

Passive network reconstruction is the process of learning a structured (networked) representation of a dynamic system through the use of known information about the structure of the system as well as data collected by observing the inputs into a system along with the resultant outputs. This work demonstrates an improvement on an existing network reconstruction algorithm so that the algorithm is capable of consistently and perfectly reconstructing a network when system inputs and outputs are measured without error. This work then extends the improved network reconstruction algorithm so that it functions even in the presence of noise as well as …

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It Is Better To Be Upside Than Sharpe!, Daniele Dapuzzo Apr 2017

It Is Better To Be Upside Than Sharpe!, Daniele Dapuzzo

Theses and Dissertations

Based on the assumption that returns in Commercial Real Estate are normally distributed, the Sharpe Ratio has been the standard risk-adjusted performance measure for the past several years. Research has questioned whether this assumption can be reasonably made. The Upside Potential Ratio as a risk-adjusted performance measure is an alternative to measure performance on a risk-adjusted basis but its values differ from the Sharpe Ratio's only in the assumption of skewed returns. We will provide reasonable evidence that CRE returns should not be fitted with a normal distribution and present the Gaussian Mixture Model as our choice of distribution to …

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Near-Salt Stratal Geometries And Implications For The Evolution Of The Onion Creek Diapir Moab, Ut, Ethan L. Cook Apr 2017

Near-Salt Stratal Geometries And Implications For The Evolution Of The Onion Creek Diapir Moab, Ut, Ethan L. Cook

Theses and Dissertations

The Onion Creek Diapir is one of many salt domes proximal to the Uncompahgre thrust front of the ancestral rockies in the Paradox Basin. It is comprised of Paradox Formation evaporites and large blocks of Honaker Trail Formation carbonates that were deformed by loading of Permian Cutler Formation progradational alluvial to fluvial fans. The history of salt movement in the Onion Creek Diapir is recorded in the near-salt strata. Large salt bodies and their adjacent mini-basins evolve conforming to a complex relationship between salt withdrawal, creating localized accommodation, and sediment deposition. Migrating mini-basin depo-centers, thinned and folded strata, and spatial …

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Weathering Sequence Of Young Basalts: A Case Study From Kohala, Hawaii, Kimberly Francis Sowards Apr 2017

Weathering Sequence Of Young Basalts: A Case Study From Kohala, Hawaii, Kimberly Francis Sowards

Theses and Dissertations

Exposed weathering profiles of a series of Pololu lava flows in Kohala, Hawaii are ideal for investigating the sequence of reactions/reaction pathways of weathered basalt. Weathering reactions for saprolites show mineral sequences that include feldspar → halloysite ± gibbsite + solutes; clinopyroxene → hematite + minor halloysite + solutes; olivine → hematite + solutes; magnetite → hematite or other Fe-oxides/hydroxides. However, the presence of smectite in four samples suggests that smectite-group clays may form as short lived intermediates at the base of the weathering profile. Regionally, on Kohala, soils and saprolites are dominated by halloysite with small quantities of other …

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Right Now Is The Wrong Time: And Other Considerations When Presenting Security Warnings, Brock Johanson, Bonnie Anderson Mar 2017

Right Now Is The Wrong Time: And Other Considerations When Presenting Security Warnings, Brock Johanson, Bonnie Anderson

Journal of Undergraduate Research

Neuro Information Security (NeuroIS) focuses on the use of neurological measurements to improve the security of information systems. The BYU NeuroIS lab uses neurological tools and measurements to examine factors that affect security outcomes. Previous work has focused on various factors such as dual task interference (DTI), threat assessment, as well as factors such as habituation and generalization, which have become focus streams of research. The primary point of failure in most security related incidents tends to be users themselves. As such, anything that can be used to overcome neurobiological phenomenon such as those listed above can ultimately lead in …

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Fabrication Of Dye Sensitized Solar Cells Using Native And Non-Native Nanocrystals In Ferritin As The Dye, Alessandro Perego, John Colton Mar 2017

Fabrication Of Dye Sensitized Solar Cells Using Native And Non-Native Nanocrystals In Ferritin As The Dye, Alessandro Perego, John Colton

Journal of Undergraduate Research

Dye-sensitized solar cells (DSSCs) present a valuable and sustainable alternative to silicon solar cells. These cells present numerous advantages compered to inorganic photovoltaic systems, such as ability of absorb more sunlight per surface area than standard silicon-based solar panels, DSSCs are also able to work even in low-light conditions such as non-direct sunlight and cloudy skies. Finally, they are economical, easy to manufacture and constructed from abundant and stable resource materials. This makes DSSCs an attractive replacement for current photovoltaic technology. Ferritin (FTN) is a 12 nm diameter spherical protein with an 8 nm hollow interior, which naturally contains iron …

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Reverse-Engineering Gene Networks That Can Remember Using The Manifold Boundary Approximation Method, Andrew White, Mark Transtrum Mar 2017

Reverse-Engineering Gene Networks That Can Remember Using The Manifold Boundary Approximation Method, Andrew White, Mark Transtrum

Journal of Undergraduate Research

Observable biological behaviors result from the interactions of microscopic elements, which form complex systems that we can model mathematically. Ideally, mechanistic models should predict a biological system’s behavior without misrepresenting the system’s biochemistry. The method of model reduction known as the Manifold Boundary Approximation Method (MBAM) [2, 3] can help us identify which parts of a model are relevant for explaining a particular behavior. This project applies MBAM to gene transcription networks that exhibit a behavior known as “memory,” the ability to retain cellular decisions to activate or silence genes. We hypothesize that MBAM can help us model the behaviors …

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Mobile Hands: What Your Phone Use Says About You, Parker Williams, Jeff Jenkins Mar 2017

Mobile Hands: What Your Phone Use Says About You, Parker Williams, Jeff Jenkins

Journal of Undergraduate Research

The percentage of individuals using mobile phones to respond to online applications, forms, and surveys is predicted to rapidly increase in the future. As of June 2, 2015, there were an estimated 2.6 billion smartphones in use in the world; by 2020 there will be 6.1 billion smartphones in use. Smartphones will account for roughly 80% of all mobile driven data traffic by 2020 (Lunden, 2015). With the proliferation of smartphones, measuring the fidelity of information gathered from and about the user becomes extremely important. Smartphones are a rich source of behavioral and biometric information, gathering data about how the …

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Intelligent Stitching: Transforming Offline Stroke Extraction For Online Handwriting Recognition, Curtis Wigington, William Barrett Mar 2017

Intelligent Stitching: Transforming Offline Stroke Extraction For Online Handwriting Recognition, Curtis Wigington, William Barrett

Journal of Undergraduate Research

Images of historical documents are being collected and archived much faster than volunteers can possibly index them alone. Improvements in offline handwriting recognition could greatly accelerate the work of indexing by FamilySearch. Offline handwriting recognition has already been shown to be effective in assisting indexers and automating the transcription of historical documents into searchable texts. As documents are collected from all around the world, generalized techniques that are robust to damage and noise are needed. Effective stroke extraction and processing is an important tool in improving current recognition techniques.

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Theory And Applications Of Network Structure Of Complex Dynamical Systems, Vasu Nephi Chetty Mar 2017

Theory And Applications Of Network Structure Of Complex Dynamical Systems, Vasu Nephi Chetty

Theses and Dissertations

One of the most powerful properties of mathematical systems theory is the fact that interconnecting systems yields composites that are themselves systems. This property allows for the engineering of complex systems by aggregating simpler systems into intricate patterns. We call these interconnection patterns the "structure" of the system. Similarly, this property also enables the understanding of complex systems by decomposing them into simpler parts. We likewise call the relationship between these parts the "structure" of the system. At first glance, these may appear to represent identical views of structure of a system. However, further investigation invites the question: are these …

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A Quaternary Climate Record From A Uinta Mountains, Usa, Fen Core With Emphasis On Sediment Pyrolysis, Samuel Abraham Hillam Mar 2017

A Quaternary Climate Record From A Uinta Mountains, Usa, Fen Core With Emphasis On Sediment Pyrolysis, Samuel Abraham Hillam

Theses and Dissertations

The northern slopes of the Uinta Mountains, Utah were previously glaciated and contain many landslides. The Tokewanna Landslide is very large and lacks Quaternary faults. Presumably, increased moisture was the failure trigger. A Quaternary climate record from a cored fen, developed in a small basin between hummocks, was reconstructed using sediment pyrolysis, biomass balance, and magnetic susceptibility. Pyrolysis is used to define Hydrogen Indices that are used to delineate wetter and drier conditions based on the kerogen type - Type III being drier, and Type II wetter. The data were matched to a time/depth curve and compared to other Uinta …

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Engineering Fret Biosensors For Microrna Presence/Absence Analysis, Nicholas E. Larkey, Sean M. Burrows Feb 2017

Engineering Fret Biosensors For Microrna Presence/Absence Analysis, Nicholas E. Larkey, Sean M. Burrows

Biomedical Engineering Western Regional Conference

No abstract provided.

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Facies Analysis, Sedimentary Petrology, And Reservoir Characterization Of The Lower Triassic Sinbad Limestone Member Of The Moenkopi Formation, Central Utah: A Synthesis Of Surface And Subsurface Data, Kristopher Michael Powell Feb 2017

Facies Analysis, Sedimentary Petrology, And Reservoir Characterization Of The Lower Triassic Sinbad Limestone Member Of The Moenkopi Formation, Central Utah: A Synthesis Of Surface And Subsurface Data, Kristopher Michael Powell

Theses and Dissertations

Lower Triassic strata in the Wellington Flat and Tully cores reflect a lateral transition from shallow water strata (Wellington Flats core) to strata that indicate deposition on a relatively more distal, storm-dominated ramp (Tully core). The Sinbad Member, along with the upper part of the underlying Black Dragon Member and the lower part of the overlying Torrey Member (Moenkopi Formation), are composed of ten carbonate, siliciclastic and mixed carbonate/siliciclastic facies deposited on a west-facing ramp/shelf that reached maximum flooding during Smithian time. Individual beds and facies display a large degree of lateral homogeneity and regional persistence in the study area. …

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A Continuous Time Model Of Centrally Controlled Motion With Random Switching Terms, J. C. Dallon, L C. Despain, E J. Evans, C P. Grant, Willaim V. Smith Jan 2017

A Continuous Time Model Of Centrally Controlled Motion With Random Switching Terms, J. C. Dallon, L C. Despain, E J. Evans, C P. Grant, Willaim V. Smith

Faculty Publications

This paper considers differential problems with random switching, with specific applications to the motion of cells and centrally coordinated motion. Starting with a differential-equation model of cell motion that was proposed previously, we set the relaxation time to zero and consider the simpler model that results. We prove that this model is well-posed, in the sense that it corresponds to a pure jump-type continuous time Markov process (without explosion). We then describe the model's long-time behavior, first by specifying an attracting steady-state distribution for a projection of the model, then by examining the expected location of the cell center when …

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Functional And Mechanistic Insight Into The Role Of Atg9a In Autophagy, Vajira Kaushalya Weerasekara Jan 2017

Functional And Mechanistic Insight Into The Role Of Atg9a In Autophagy, Vajira Kaushalya Weerasekara

Theses and Dissertations

The bulk degradative process of macroautophagy requires the dynamic growth of autophagosomes, which carry cellular contents to the lysosome for recycling. Atg9A, a multi-pass transmembrane protein, is an apical regulator of autophagosome growth, yet its regulatory mechanism remains unclear. Our work suggests that hypoxia (low glucose and oxygen) triggers a rearrangement of the small adapter protein 14-3-3ζ interactome. Our data suggest that the localization of mammalian Atg9A to autophagosomes requires phosphorylation on the C terminus of Atg9A at S761, which creates a 14-3-3z docking site. Under basal conditions, this phosphorylation is maintained at a low level and is dependent on …

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"I Can Physically Feel The Difference": Exploring Physicalizations Of Running Data, Zann Benjamin Anderson Jan 2017

"I Can Physically Feel The Difference": Exploring Physicalizations Of Running Data, Zann Benjamin Anderson

Theses and Dissertations

We explore user interactions with concrete physical visualizations—physicalizations—of personal experiential data. We conducted three user studies involving physicalizations of data gathered while trail running—a sport in which participants are largely more focused on the experience than the exercise itself. In two qualitative studies, we asked trail runners to give us a GPS path from a "significant run" and then prepared a 3D physicalization featuring the path overlaid as a raised line on the corresponding real-world terrain. In the first, physicalizations had a significant impact in helping participants recall memories of their experiences, and participants shared many stories. In a follow-up …

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A Semi-Automatic Grading Experience For Digital Ink Quizzes, Brooke Ellen Rhees Jan 2017

A Semi-Automatic Grading Experience For Digital Ink Quizzes, Brooke Ellen Rhees

Theses and Dissertations

Teachers who want to assess student learning and provide quality feedback are faced with a challenge when trying to grade assignments quickly. There is currently no system which will provide both a fast-to-grade quiz and a rich testing experience. Previous attempts to speed up grading time include NLP-based text analysis to automate grading and scanning in documents for manual grading with recyclable feedback. However, automated NLP systems all focus solely on text-based problems, and manual grading is still linear in the number of students. Machine learning algorithms exist which can interactively train a computer quickly classify digital ink strokes. We …

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Redbeds Of The Upper Entrada Sandstone, Central Utah: Facies Analysis And Regional Implications Of Interfingered Sabkha And Fluvial Terminal Splay Sediments, Jeffery Michael Valenza Dec 2016

Redbeds Of The Upper Entrada Sandstone, Central Utah: Facies Analysis And Regional Implications Of Interfingered Sabkha And Fluvial Terminal Splay Sediments, Jeffery Michael Valenza

Theses and Dissertations

First distinguished from other sedimentary successions in 1928, the Entrada Sandstone has been the subject of numerous studies. The western extent of the formation was initially described as laterally continuous "earthy" red beds, and categorized as sub- to supratidal marine-influenced sediments. Recent workers have reexamined the sedimentary facies hosted by the Entrada Sandstone, and findings suggest purely terrestrial depositional environments. Several outcrops of the upper Entrada hosted peculiar sedimentary features, including undulatory and convex-upward, parallel-laminated bedforms, reminiscent of hummocky cross-stratification- unexpected features in a terrestrial environment. The purpose of this study was to collect detailed outcrop measurements of these and …

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Structural Analysis Of Cell Signaling Complexes, Takuma Aoba Dec 2016

Structural Analysis Of Cell Signaling Complexes, Takuma Aoba

Theses and Dissertations

Bardet-Biedl syndrome (BBS) is a rare genetic disease that causes retinal degradation, obesity, kidney dysfunction, polydactyly, and other cilium-related disorders. To date, more than 20 BBS genes, whose mutants cause BBS phenotypes, have been identified, and eight of those (BBS1-2, 4-5, 7-9, and 18) are known to form the BBSome complex. Recent studies have revealed that the BBSome is closely involved in the trafficking of signaling proteins in the primary cilium. Mutations in BBS genes are highly pathogenic because trafficking in the primary cilium is not fully functional when BBS mutations impair assembly of the BBSome. However, the functional links …

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Control Of Matrix Metalloproteinases In A Periodontitis Model: Molecules That Trigger Or Inhibit Mmp Production, Catalina Matias Orozco Dec 2016

Control Of Matrix Metalloproteinases In A Periodontitis Model: Molecules That Trigger Or Inhibit Mmp Production, Catalina Matias Orozco

Theses and Dissertations

In periodontitis, there is a disruption in the homeostasis of the oral microbiome by peridontopathogenic bacteria. However, while bacteria is essential for periodontitis to occur, the severity, pattern and progression of the disease is not solely determined by the microbial burden, and in fact has a lot to do with the overwhelming host inflammatory response. The response can vary even in two individuals with similar periodontopathogenic profiles. The host response leads to extracellular matrix (ECM) destruction, loss of attachment, alveolar bone resorption and eventually, edentulism. The host's reaction is orchestrated by proinflammatory cytokines and chemokines and matrix metalloproteinases (MMPs). MMPs …

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Some Spectral Properties Of A Quantum Field Theoretic Hamiltonian, Devin Burnell Mcghie Dec 2016

Some Spectral Properties Of A Quantum Field Theoretic Hamiltonian, Devin Burnell Mcghie

Theses and Dissertations

We derive the ground-state eigenvalues and eigenvectors for a simplified version of the 1-D QED single electron-photon model that Glasgow et al recently developed [2]. This model still allows for meaningful interaction between electrons and photons while keeping only the minimum needed to do so. We investigate the interesting spectral properties of this model. We determine that the eigenvectors are orthogonal as one would expect and normalize them.

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Investigation Of Dynamic Biological Systems Using Direct Injection And Liquid Chromatography Mass Spectrometry, Adam Clayton Swensen Dec 2016

Investigation Of Dynamic Biological Systems Using Direct Injection And Liquid Chromatography Mass Spectrometry, Adam Clayton Swensen

Theses and Dissertations

In biological systems, small changes can have significant impacts. It is, therefore, very important to be able to identify these changes in order to understand what is occurring in the organism. In many cases, this is not an easy task. Mass spectrometry has proven to be a very useful tool in elucidating biological changes even at a very small scale. Several different mass spectrometry based techniques have been developed to discover and investigate complex biological changes. Some of these techniques, such as proteomics, have been through years of development and have advanced to the point that anyone can complete complex …

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Algorithms For Learning The Structure Of Monotone And Nonmonotone Sum-Product Networks, Aaron W. Dennis Dec 2016

Algorithms For Learning The Structure Of Monotone And Nonmonotone Sum-Product Networks, Aaron W. Dennis

Theses and Dissertations

The sum-product network (SPN) is a recently-proposed generative, probabilistic model that is guaranteed to compute any joint or any marginal probability in time linear in the size of the model. An SPN is represented as a directed, acyclic graph (DAG) of sum and product nodes, with univariate probability distributions at the leaves. It is important to learn the structure of this DAG since the set of distributions representable by an SPN is constrained by it. We present the first batch structure learning algorithm for SPNs and show its advantage over learning the parameters of an SPN with fixed architecture. We …

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Facies Analysis And Depositional Environments Of The Saints & Sinners Quarry In The Nugget Sandstone Of Northeastern Utah, Jesse Dean Shumway Dec 2016

Facies Analysis And Depositional Environments Of The Saints & Sinners Quarry In The Nugget Sandstone Of Northeastern Utah, Jesse Dean Shumway

Theses and Dissertations

The Saints & Sinners Quarry preserves the only known vertebrate body fossils in the Nugget Sandstone and the most diverse fauna known from the Nugget-Navajo-Aztec erg system. The fauna includes eight genera and >18,000 bone and bone fragments assignable to >76 individuals, including theropods, sphenosuchians, sphenodontians, drepanosaurs, procolophonids, and a dimorphodontid pterosaur. Cycadeoid fronds are the only plant fossils. There are two depositional environments at the site – dune and interdune, each consisting of two or more faces. The dune facies are (1) Trough Cross-Stratified Sandstone (TCS) representing dry dunes, and (2) Massive and Bioturbated Dunes (MBD) representing bioturbated, damp …

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Direct Band Gap Measurements, John Ryan Peterson Nov 2016

Direct Band Gap Measurements, John Ryan Peterson

Student Works

This presentation was given during the summer of 2016 as part of the BYU REU program funded by the NSF. Here I give a brief explanation of our quantum dot synthesis and then explain the mechanism of photoluminsecence used to measure indirect band gap energies of semiconductors. Our experimental setup is shown. Direct band gaps of lead sulfide quantum dots synthesized in ferritin are reported. The data show that the band gap can be tuned arbitrarily in a certain range by varying the concentrations of the reactants. We compare stability of quantum dots in ferritin to quantum dots synthesized without …

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Determining The Index Of Refraction Of Aluminum Fluoride In The Ultra Violet Spectrum, Zoe Hughes Nov 2016

Determining The Index Of Refraction Of Aluminum Fluoride In The Ultra Violet Spectrum, Zoe Hughes

Student Works

A NASA project called Large UV/Optical/Infrared Surveyor (LUVOIR) is looking into ways to coat a mirror for a new space telescope. We contributed to this project by investigating aluminum fluoride (AlF3) as a possible coating for the mirror. We measured the index of refraction of AlF3 in the wavelength range 6 – 49.5 nm by testing three sample mirrors, each made up of a silicon wafer with a coating of AlF3. We took data at the Advanced Light Source (ALS) in Berkeley, California and in the laboratory at Brigham Young University (BYU). There are discrepancies …

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Quantum Dot Band Gap Measurements, John Ryan Peterson Nov 2016

Quantum Dot Band Gap Measurements, John Ryan Peterson

Student Works

This presentation was given during the summer of 2016 as part of the BYU REU program funded by the NSF. Here I give a brief explanation of our quantum dot synthesis as well as explain the use of absorption spectroscopy to measure indirect band gap energies of semiconductors. Our experimental setup is shown and recent improvements are explained. We report indirect band gaps of quantum dots containing varying amounts of cobalt oxide and manganese oxide and synthesized in the protein ferritin. The data show that the band gap can be tuned arbitrarily in a certain range by varying the concentrations …

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Quantum Dot Band Gap Investigations, John Ryan Peterson Nov 2016

Quantum Dot Band Gap Investigations, John Ryan Peterson

Student Works

Improving solar panel efficiency has become increasingly important as the world searches for cheap renewable energy. Recent developments in the industry have focused on multi-layer cells, some of which use semiconducting dyes to absorb light in place of crystalline solids. In this paper, I characterize various dyes recently synthesized for use in solar panels. These dyes contain semiconducting nanoparticles enclosed primarily by the protein ferritin to limit particle size. The band gaps were measured using either optical absorption spectroscopy or measuring the photoluminescence spectrum, depending on the type of semiconductor. The results indicate that both manganese oxide and lead sulfide …

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Towards Using Certificate-Based Authentication As A Defense Against Evil Twins In 802.11 Networks, Travis S. Hendershot Nov 2016

Towards Using Certificate-Based Authentication As A Defense Against Evil Twins In 802.11 Networks, Travis S. Hendershot

Theses and Dissertations

Wireless clients are vulnerable to exploitation by evil twins due to flaws in the authentication process of 802.11 Wi-Fi networks. Current certificate-based wireless authentication protocols present a potential solution, but are limited in their ability to provide a secure and usable platform for certificate validation. Our work seeks to mitigate these limitations by exploring a client-side strategy for utilizing alternative trust models in wireless network authentication. We compile a taxonomy of various trust models for conducting certificate-based authentication of wireless networks and methodically evaluate each model according to desirable properties of security, usability, and deployability. We then build a platform …

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