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Articles 241 - 270 of 8341

Full-Text Articles in Physical Sciences and Mathematics

Structural, Functional And Biochemical Studies To Elucidate The Molecular Basis Of Xenobiotic Metabolism Of Tetranychus Uritcae, A Major Agricultural Pest, Ricardo Hernandez Arriaza Oct 2023

Structural, Functional And Biochemical Studies To Elucidate The Molecular Basis Of Xenobiotic Metabolism Of Tetranychus Uritcae, A Major Agricultural Pest, Ricardo Hernandez Arriaza

Theses and Dissertations

The two-spotted spider mite, Tetranychus urticae, is a major cosmopolitan pest that feeds on more than 1,100 plant species, including 150 crops. Such a wide host range indicates this mite’s unparalleled xenobiotic responsiveness that is also coincident with their ability to rapidly develop resistance to pesticides. An unprecedently large detoxifying machinery is one of the main biological traits responsible for their extraordinary adaptation potential and devastating effect on crops. Availability of the whole genome sequence revealed expansions in all major detoxifying families and demonstrated that this genome has been enriched by horizontally transferred genes from bacteria and fungi. Motivated by …

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Recovering Lost Exposure From The Majorana Demonstrator And Testing Data Selection Assumptions, Thomas Lannen Oct 2023

Recovering Lost Exposure From The Majorana Demonstrator And Testing Data Selection Assumptions, Thomas Lannen

Theses and Dissertations

The Majorana Demonstrator recently concluded its search for neutrinoless double beta decay using an array of up to 40.4kg of germanium detectors, 27kg of which were enriched in 76Ge and housed inside a copper and lead compact shield located at the 4850 foot level in a clean room in the Davis Campus of the Sanford Underground Research Facility (SURF) in Lead, South Dakota. This search proceeded from June 26, 2015 until March 3, 2021 and 64.5 kg yr of enriched active exposure was acquired while achieving a world leading energy resolution of 0.12% FWHM at 2039 keV, one of …

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A Field-Programmable Metamaterial Using Memristor As A Stable Switcher, Taekuk Hong Oct 2023

A Field-Programmable Metamaterial Using Memristor As A Stable Switcher, Taekuk Hong

Theses and Dissertations

Before the memristor was discovered, there were RLC circuits as representative passive devices. However, the fourth fundamental two-terminal circuit has been discovered by Dr. Leon Chua in 1971 and has been called a memristor. The memristor is a compound word of memory and resistor, and is an element whose resistive value is not constant and whose resistive value changes depending on the applied voltage and is recorded as a memory. It is mainly used in resistive switching and is the center of this research theme. A metamaterial is artificially created material that has never been found in nature. The theory …

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A Method For Single-Particle Magnetic Particle Spectroscopy With A Nanofabricated Coplanar Stripline, Jacob Martin Oct 2023

A Method For Single-Particle Magnetic Particle Spectroscopy With A Nanofabricated Coplanar Stripline, Jacob Martin

Theses and Dissertations

Drawing from magnetic particle imaging principles, magnetic particle spectroscopy (MPS) serves as a valuable tool employing superparamagnetic iron-oxide nanoparticles (SPIONs) in diverse applications ranging from medical imaging to biosensing and the comprehensive study of magnetic particles’ characteristics. MPS leverages the nonlinear response exhibited by SPIONs when a external magnetic field is applied, enabling a highly sensitive method for examining biological systems and more. However, conventional MPS setups demand a high particle concentration of approximately 10^15 particles per liter to generate a detectable response. The first objective of this work is to simulate the dynamics of a system with the ability …

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Robocat: An Autonomous Surface Vehicle (Asv) For Near-Surface Hydrodynamic Measurements In Buoyant Plumes. Development And Case Study, Christopher Tom Papageorgiou Oct 2023

Robocat: An Autonomous Surface Vehicle (Asv) For Near-Surface Hydrodynamic Measurements In Buoyant Plumes. Development And Case Study, Christopher Tom Papageorgiou

Theses and Dissertations

The study of near surface processes in plumes and other stratified environments requires the collection of hydrodynamic and hydrographic data near the sea surface at high temporal and spatial (in the vertical) resolution. This need led to the design and development of a low-cost autonomous surface vehicle (ASV) equipped with a 5-beam acoustic Doppler current profiler (Nortek 1000 Signature) capable of measuring the vertical structure of both mean flow and turbulence dissipation rate (ε) as close as 30 cm below the sea surface. The ASV is a small catamaran-like platform propelled by four thrusters arranged in an Omni-X configuration, to …

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Investigation, Synthesis And Rational Design Of Novel Transuranic Containing Extended Structures, Adrian Thomas Hines Oct 2023

Investigation, Synthesis And Rational Design Of Novel Transuranic Containing Extended Structures, Adrian Thomas Hines

Theses and Dissertations

The use of nuclear technology has proven useful for energy generation and for weapons manufacturing, but disposal and storage of nuclear waste is an ongoing problem. The accumulation of nuclear waste over the past decades has yielded a vast amount of waste that must be dealt with, and with space at interim storage facilities diminishing, it has become increasingly important to find solutions to nuclear waste storage. The vitrification process has been widely accepted as a viable route for immobilization of high-level waste; however, the process is inadequate for complex waste streams and has many drawbacks such as limited waste …

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Reactive Molecular Dynamics Of Large Systems: Quantum Dynamics With Adaptable Gaussian Bases; Hydroxide Diffusion In A Polymeric Environment, Mohottige Sachith Prasanga Wickramasinghe Oct 2023

Reactive Molecular Dynamics Of Large Systems: Quantum Dynamics With Adaptable Gaussian Bases; Hydroxide Diffusion In A Polymeric Environment, Mohottige Sachith Prasanga Wickramasinghe

Theses and Dissertations

This dissertation describes our research in theory and applications of reactive molecular dynamics. Quantum dynamics provides the foundation for understanding chemical processes. However, the computational cost of describing a general quantum system scales exponentially with the system size. Thus, an efficient basis representation of wavefunctions is essential. Time-dependent Gaussian bases are often employed to describe the large-amplitude motion of high-dimensional systems. The time dependence of such bases is typically determined by (i) the variational principle or by (ii) classical dynamics. But those approaches have shortcomings due to intrinsic singularity of the variational equations in the full basis limit or due …

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Fundamental Study Of Ionic Liquid Physicochemical Effects On Thermal Stability Of Model Biological Macromolecules, Austin Keith Clark Sep 2023

Fundamental Study Of Ionic Liquid Physicochemical Effects On Thermal Stability Of Model Biological Macromolecules, Austin Keith Clark

Theses and Dissertations

Ionic Liquids (ILs) are substances with a unique physical attribute compared to that of solid ionic salts. At room temperature, ILs are molten salts that have a variety of physical effects that can play a role in their impact on other molecules, as solvents or solutes. They can play the role of the solvent in a variety of applications, from biofuels to organic catalysis or as excipients in pharmaceutical formulations. These ILs have a desirable use as solvents due to their ability to be tunable substances. Changing the cation or anion of the IL causes a change in its physical …

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Machine Learning And Causality For Interpretable And Automated Decision Making, Maria Lentini Sep 2023

Machine Learning And Causality For Interpretable And Automated Decision Making, Maria Lentini

Theses and Dissertations

This abstract explores two key areas in decision science: automated and interpretable decision making. In the first part, we address challenges related to sparse user interaction data and high item turnover rates in recommender systems. We introduce a novel algorithm called Multi-View Interactive Collaborative Filtering (MV-ICTR) that integrates user-item ratings and contextual information, improving performance, particularly for cold-start scenarios. In the second part, we focus on Student Prescription Trees (SPTs), which are interpretable decision trees. These trees use a black box "teacher" model to predict counterfactuals based on observed covariates. We experiment with a Bayesian hierarchical binomial regression model as …

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Identity Management Pki System Using Blockchain, Mohamed Abdel Fattah Abdel Baki Awad Sep 2023

Identity Management Pki System Using Blockchain, Mohamed Abdel Fattah Abdel Baki Awad

Theses and Dissertations

Identity management is one of the most important topics in the security field. Public Key Infrastructure (PKI) is the most commonly used approach in legally identity management systems. PKI systems have many centralized services that might affect the availability and trustworthiness of the system. Issues related to certificate verification methods such as Certificate Revocation List (CRL) and Online Certificate Status Protocol (OCSP) can be avoided if blockchain is used. Blockchain is a decentralized trusted system where data can only be appended to a public ledger. Edits are not allowed in blockchain. Blockchain consists of several nodes all of them have …

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Methods Of Evaluating Quantum Phase Estimation Circuit Output, Charles A. Woodrum Sep 2023

Methods Of Evaluating Quantum Phase Estimation Circuit Output, Charles A. Woodrum

Theses and Dissertations

The quantum phase estimation (QPE) algorithm is one of the most important quantum computing algorithms that has been developed. The QPE algorithm estimates the phase or phases of the eigenvalue or eigenvalues of a unitary operator. It is a critical step for applications like Shor’s algorithm for factoring and the HHL algorithm for solving linear systems of equations, but it remains difficult to implement on current quantum computers due to small numbers of logical qubits and high error rates. This investigation derives a more accurate estimation of the phase of a unitary operator than would otherwise be attained with the …

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Leveraging Galois Theory And Computational Results In The Search For Legendre Pairs, David M. Arquette Sep 2023

Leveraging Galois Theory And Computational Results In The Search For Legendre Pairs, David M. Arquette

Theses and Dissertations

With applications spanning myriad disciplines, Hadamard matrices have tremendous utility. Infinitely many have been discovered, but there is no general proof of their existence. Proving the Hadamard conjecture would provide a significant technological edge. Hadamard matrices are difficult to construct in general; however, they can be created directly from Legendre pairs (LPs). While LPs are not trivial to find, a breakthrough in this area would be pivotal in the quest to prove the Hadamard conjecture. Most recent efforts rely upon refined search algorithms, and we seek to either develop a better such algorithm or discover an altogether new theoretical construction. …

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Steady State Thermal Blooming With Convection: Modeling, Simulation And Analysis, Jeremiah S. Lane Sep 2023

Steady State Thermal Blooming With Convection: Modeling, Simulation And Analysis, Jeremiah S. Lane

Theses and Dissertations

The modeling, simulation, and analysis of high energy laser propagation is a research topic of significant interest to the defense community. A detailed understanding of the phenomenon of thermal blooming is crucial as it is detrimental to the propagation of lasers over long distances and in the presence of aerosols. The simulation of thermal blooming has historically relied on wave optics models and scaling laws for the fluid response to the laser. Since thermal blooming occurs in the presence of natural convection, however, there is a need for simulating this coupled fluid-beam effect using a first principles approach. In this …

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Numerical Simulation Of Nonlinear Wave Equations With Machine Learning, Kristina O. F. Williams Sep 2023

Numerical Simulation Of Nonlinear Wave Equations With Machine Learning, Kristina O. F. Williams

Theses and Dissertations

A machine learning procedure is proposed to create numerical schemes for solutions of certain types of nonlinear wave equations on coarse grids. This method trains stencil weights of a discretization of the equation, with the truncation error of the scheme as the objective function for training. A neural network is used as a model for the stencil weights. The method uses centered finite differences to initialize the optimization routine and a second-order implicit-explicit time solver as a framework. Symmetry conditions are enforced on the learned operator to ensure a stable method. The procedure is applied to the Korteweg - de …

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Improving Deep Reinforcement Learning Methodology For Autonomous Defense And Escort Of Military High-Value Assets, Joseph Liles Iv Sep 2023

Improving Deep Reinforcement Learning Methodology For Autonomous Defense And Escort Of Military High-Value Assets, Joseph Liles Iv

Theses and Dissertations

This dissertation explores the application of machine learning to the control of autonomous unmanned combat aerial vehicles (AUCAVs). In particular, this research applies deep reinforcement learning methodologies to a defensive air combat scenario wherein a fleet of AUCAVs protects a military high-value asset (HVA). A collection of air battle management scenarios along with an original simulation environment and a set of designed computational experiments support the approximation of high-quality decision policies by employing Markov decision processes, approximate dynamic programming algorithms, and deep neural networks for value function approximation.

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Advances In Quaternion-Valued Neural Networks, Jeremiah P. Bill Sep 2023

Advances In Quaternion-Valued Neural Networks, Jeremiah P. Bill

Theses and Dissertations

This dissertation investigates the construction, optimization, and application of quaternion neural networks (QNNs) to Department of Defense (DoD) related problem sets. QNNs are a type of neural network wherein the weights, biases, and input values are all represented as quaternion numbers. This work provides a critical evaluation of the myriad different quaternion backpropagation derivations that exist in the literature, testing the performance of each on a range of regression problem sets. The optimization dynamics of QNNs are explored, presenting visualizations of QNN loss surfaces and a novel method for assessing the “smoothness” of these loss surfaces. Finally, this dissertation presents …

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Advanced Statistical Methodology For The Modern Probability Of Detection, Christine E. Knott Sep 2023

Advanced Statistical Methodology For The Modern Probability Of Detection, Christine E. Knott

Theses and Dissertations

Probability of detection (POD) is an invaluable part of the calculations used by the USAF to validate the capabilities of nondestructive inspection systems for detecting defects in critical structural components on aircraft. A POD study consists of a designed experiment, linear modeling, and a probability of detection verses defect size curve. This curve is useful for determining how often an aircraft should be re-inspected. Some POD studies are unsuccessful in creating realistic POD curves because the statistical modeling used has two common limitations: (1) a lack of convergence leading to no solution and, (2) violated assumptions leading to incorrect solutions. …

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Countnet3d: A 3d Computer Vision Approach To Infer Counts Of Occluded Objects With Quantified Uncertainty, Stephen W. Nelson Aug 2023

Countnet3d: A 3d Computer Vision Approach To Infer Counts Of Occluded Objects With Quantified Uncertainty, Stephen W. Nelson

Theses and Dissertations

3D scene understanding is an important problem that has experienced great progress in recent years, in large part due to the development of state-of-the-art methods for 3D object detection. However, the performance of 3D object detectors can suffer in scenarios where extreme occlusion of objects is present, or the number of object classes is large. In this paper, we study the problem of inferring 3D counts from densely packed scenes with heterogeneous objects. This problem has applications to important tasks such as inventory management or automatic crop yield estimation. We propose a novel regression-based method, CountNet3D, that uses mature 2D …

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Undergraduate Students' Conceptions Of Ngss Science And Engineering Practices, Jessie Webb Aug 2023

Undergraduate Students' Conceptions Of Ngss Science And Engineering Practices, Jessie Webb

Theses and Dissertations

In 2013, a new set of science standards was introduced for K-12 science education, called the Next Generation Science Standards (NGSS), which focused on three dimensions of science learning that work together: disciplinary core ideas, crosscutting concepts, and science and engineering practices. These standards are novel in their emphasis on students needing more than only content knowledge to learn science and engineering. The NGSS science and engineering practices (SEPs) stress the importance of students engaging in the authentic practices of scientists and engineers to help them think like a scientist, practice science themselves, and overcome the misconception that science is …

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A Colorfully Natural Twin Higgs Model, Logan Coleman Page Aug 2023

A Colorfully Natural Twin Higgs Model, Logan Coleman Page

Theses and Dissertations

Twin Higgs models have the potential to explain phenomena outside of the Standard Model and provide an natural explanation of the Higgs mass. Here I explore a new realization of the twin Higgs concept with an SU(4)c symmetry that is spontaneously broken in the Standard Model sector, but remains unbroken in the Twin sector. I detail the phenomenological results produced by this model. I show that this construction leads to a qualitatively new behavior regarding the fine-tuning of the Higgs mass due to the top-quark sector.

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Enhanced Capabilities For Investigating Local Structure And Magnetism: Three Dimensional Magnetic Pair Distribution Function And Symmetry Mode Analysis, Parker Hamilton Aug 2023

Enhanced Capabilities For Investigating Local Structure And Magnetism: Three Dimensional Magnetic Pair Distribution Function And Symmetry Mode Analysis, Parker Hamilton

Theses and Dissertations

The local structure, atomic and magnetic structure correlated over a small length scale, of a material has a strong impact on material properties. Pair distribution function (PDF) analysis is a strong tool to investigate local structure and magnetism of this nature. This work outlines extensions to current one dimensional magnetic pair distribution functions (1D-mPDF) and the fitting of structures with symmetry breaking local atomic distortions. 1DmPDF analysis has been used to study local magnetic structure, but requires a rotational averaging of the correlations so directional information is lost, as in powder diffraction experiments. Three dimensional difference magnetic pair distribution function …

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Constructing Stellar Mass Models For Early-Type Galaxies With Circumnuclear Disks, Jared R. Davidson Aug 2023

Constructing Stellar Mass Models For Early-Type Galaxies With Circumnuclear Disks, Jared R. Davidson

Theses and Dissertations

Dusty circumnuclear disks (CNDs) in luminous early-type galaxies (ETGs) show regular, dynamically cold molecular gas kinematics. For a growing number of these ETGs, Atacama Large Millimeter/sub-millimeter Array (ALMA) CO imaging and detailed gas-dynamical modeling have yielded moderate to high precision black hole (BH) mass (M_BH) determinations. To date, however, few studies have explored the effects of dust attenuation, or uncertainties in dust corrections, on recovered stellar luminosity models from high angular resolution optical/near-IR observations and M_BH measurements. Recent kinematic studies that modeled ALMA CO data sets have found that uncertainties in the intrinsic central stellar surface brightness slope due to …

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Phosphorus Sorption And Kinetics Across The Sediment-Water Interface Of Utah Lake, A Shallow Eutrophic Lake, Forrest Fielding Stretch Jarvis Jarvis Aug 2023

Phosphorus Sorption And Kinetics Across The Sediment-Water Interface Of Utah Lake, A Shallow Eutrophic Lake, Forrest Fielding Stretch Jarvis Jarvis

Theses and Dissertations

Internal sediment phosphorus (P) cycling may regulate harmful algal blooms (HABs) in shallow eutrophic lakes. Utah Lake frequently experiences HABs despite its high alkalinity and P-rich sediment. Phosphorus cycling between the lakebed and the water column is dependent upon stable P-sorption with organic matter (OM) and mineral species, which can vary with substrate availability, P-concentrations, temperature, redox, pH, and microbial activity. A full biogeochemical analysis of the water and sediment across seven sites shows Utah Lake to be spatially well-mixed in terms of composition and sorption, with few exceptions. Sediment P-concentrations (avg. 677 mg-P kg-1) primarily correlate with redox-sensitive iron …

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Detailed Characterization Of Material Deformation, Alexander J. Farnsworth Aug 2023

Detailed Characterization Of Material Deformation, Alexander J. Farnsworth

Theses and Dissertations

This dissertation presents a comprehensive exploration of material deformation at the atomic level, investigating key findings and contributions through three fundamental methods: Sum Frequency Generation Spectroscopy (SFG), X-ray Diffraction (XRD), and Electron Backscatter Diffraction (EBSD). The research commences by uncovering the material dependency of nonresonant responses in both SFG and Second Harmonic Generation (SHG) signals. This redefinition of the nonresonant component as an information-rich carrier, rather than mere background noise, leads to novel insights into the potential applications of SFG. The study then delves further into the influence of mechanical stress on materials, establishing a connection between dislocation density on …

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Measuring Microparticle Adhesion Via High-Speed Rotor, Jacob C. Fearnley Aug 2023

Measuring Microparticle Adhesion Via High-Speed Rotor, Jacob C. Fearnley

Theses and Dissertations

Much is known about the atomic/molecular theories that govern adhesion as well as the macroscopic aspects and properties of adhesion. However, adhesion in the microparticle regime is poorly characterized. We report on experiments that use centrifugal force to remove polystyrene (PS) particles from the surface of a high-speed titanium rotor operated in vacuum. This unique rotor can apply forces far greater than other centrifugal force methods or related techniques using atomic force spectroscopy. The mode of attachment, whether particles were located on the windward side versus leeward side of the spinning rotor, time spent in vacuum prior to experiments, and …

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Terahertz From Electrons, Electronics From Terahertz, Clayton D. Moss Aug 2023

Terahertz From Electrons, Electronics From Terahertz, Clayton D. Moss

Theses and Dissertations

Time-domain terahertz spectroscopy (THz-TDS) is a valuable technique for studying collective ultrafast phenomena. Several mechanisms exist for converting ultrashort optical laser pulses into coherent THz sources. Broadband THz pulses can be obtained from electron currents in air plasma, which requires combinations of different colors of light to be most effective. I report multi-color generation schemes of THz pulses that deliver coherent THz output. Experimental and theoretical work using the photocurrent model describe ways to use non-harmonic color combinations to utilize several sources of light available in a table-top laser setup. Additionally, THz-TDS is used to study a variety of ultrafast …

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The Role Of Cytosolic Chaperonin Cct And Its Co-Chaperone Phlp1 In Folding And Assembly Of Signaling Complexes, Yujin Kwon Aug 2023

The Role Of Cytosolic Chaperonin Cct And Its Co-Chaperone Phlp1 In Folding And Assembly Of Signaling Complexes, Yujin Kwon

Theses and Dissertations

CCT, a large (1 MDa) protein-folding machine, is a eukaryotic group II chaperonin that is essential for folding many cellular proteins and is the most complex of all chaperonins with two rings each composed of eight paralogous subunits. CCT captures proteins in its folding chamber to assist the folding of its substrates. CCT utilizes ATP hydrolysis to open and close its chamber and fold its substrates. CCT has been shown to be important in the folding of proteins with - propeller domains which consist of seven WD40 repeat sequences that fold into -sheets that form the blades of a propeller-like …

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The Influence Of Political Media On Large Language Models: Impacts On Information Synthesis, Reasoning, And Demographic Representation, Alexander Glenn Shaw Aug 2023

The Influence Of Political Media On Large Language Models: Impacts On Information Synthesis, Reasoning, And Demographic Representation, Alexander Glenn Shaw

Theses and Dissertations

This thesis investigates the impact of finetuning the LLaMA 33B language model on partisan news datasets, revealing negligible changes and underscoring the enduring influence of pretraining datasets on model opinions. Training nine models across nine distinct news datasets spanning three topics and two ideologies, the study found consistent demographic representation, predominantly favoring liberal, college-educated, high-income, and non-religious demographics. Interestingly, a depolarizing effect emerged from partisan news finetuning, suggesting that intense exposure to topic-specific information might lead to depolarization, irrespective of ideological alignment. Despite the exposure to contrasting viewpoints, LLaMA 33B maintained its common sense reasoning ability, showing minimal variance on …

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Separation Of Perrhenate And Perfluoroalkyl Substances By Ion Chromatography With Customized Stationary Phases, Wai Ning Chan Aug 2023

Separation Of Perrhenate And Perfluoroalkyl Substances By Ion Chromatography With Customized Stationary Phases, Wai Ning Chan

Theses and Dissertations

Ion exchange chromatography (IC) is an analytical technique used to separate charged molecules including ions, proteins, small nucleotides, and amino acids. It can function in anion or cation mode. In this dissertation, anion exchange chromatography was used, and column materials were made in our lab with resorcinarene-based compounds called cavitands. Cavitands create cavities to bind to molecules because of their three-dimensional structure. Two new gradient IC methods were established to identify and quantify perrhenate and perfluoroalkyl substances (PFAS) by customized resorcinarene-based column, zinc cyclen resoecinarene (ZCR) and arginine methyl ester (RUE) columns. The ZCR column accomplished outstanding separation of perrhenate …

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Improved Endmember Mixing Analysis (Emma): Application To A Nested Catchment, Provo River, Northern Utah, Alyssa Nicole Thompson Aug 2023

Improved Endmember Mixing Analysis (Emma): Application To A Nested Catchment, Provo River, Northern Utah, Alyssa Nicole Thompson

Theses and Dissertations

An endmember mixing analysis (EMMA) is a hydrograph separation technique used to identify and quantify stream source contributions, but the error within the results of the analysis itself can be difficult to quantify. Employing EMMA to accurately quantify these contributions is particularly important for critical watersheds that supply water to large populations, such as montane watersheds. We applied EMMA to the Provo River, a nested catchment with three monitoring locations in northern Utah, to understand the limitations and potential improvements that could be made to EMMA. Four main endmembers (quartzite groundwater, soil water, snow and carbonate groundwater) were identified for …

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