Physical Sciences and Mathematics Commons^™

Application Of Mass Spectrometry For The Characterization Of Synthetic Oligomers And Natural Lignin, Poorya Kamali

Theses and Dissertations--Chemistry

As part of the ongoing effort to substitute finite fuel and chemical resources with renewable ones, biomass is emerging as one of the most promising sources. Biomass consists of three main components of cellulose, hemicellulose, and lignin. Traditionally, cellulose has been used extensively in pulping industry, while lignin has been considered waste and is burned to generate heat. Lignin, a complex aromatic polymer component of biomass, has the potential to be used as a source of aromatic chemicals and pharmaceutical synthons. The recalcitrant nature of lignin, the lack of effective lignin breakdown methods and analytical techniques to analyze it are …

Development Of An Effective Au:Pd Bimetallic Heterogeneous Catalyst For Oxidative Lignin Depolymerization To Low Molecular Weight Aromatics, Gayan P. Karunasinghe

Theses and Dissertations--Chemistry

The principal concept behind biorefining involves the transformation of lignocellulosic biomass into valuable products and energy resources. Historically, biorefinery strategies for lignocellulosic biomass have primarily focused on improving the conversion of cellulose into ethanol, often neglecting the underutilized lignin component. Lignin consists of phenolic subunits, from which it follows that value-added products can be obtained from lignin depolymerization. Unfortunately, lignin utilization is particularly challenging due to its high structural irregularity and recalcitrance. The goal of this study was to develop an AuPd/Li-Al layered double hydroxide (LDH) bimetallic catalyst for efficient lignin depolymerization, resulting in the production of high-value aromatic compounds. …

Mapping For Accountability: Decolonizing Land Acknowledgment Initiatives, Salma Monani, Sarah E. Gilsoul

Environmental Studies Faculty Publications

What does it mean to map Indigenous presence onto lands that have been appropriated by settler colonial nation states? This chapter examines the challenges and potentials of re-inscribing Indigenous land relations through a digital mapping project, Indigenous Pennsylvania: Past, Present and Future. Situating itself within the growing scholarship of Indigenous cartographies, the chapter presents Indigenous Pennsylvania as an example of d-ecomedia, a shorthand we offer for ecomedia projects that foreground decolonial methodologies. Such methodologies prompt us to attend to a storied sense of Indigenous place-based relations through attention to Indigenous spatial and temporal modes of mediation.

Mitigation Of Cache Attacks On Cloud Services, Mudassiruddin Mohammed

All Student Theses and Dissertations

Cloud computing is frequently used due to its low cost and flexibility, but it also raises security issues to cloud service providers and customers. Cache attacks are a critical security risk in cloud computing. Cache attacks use weaknesses in cloud servers' cache memory to steal sensitive information, interrupt services, and decrease cloud performance. This study examines the many forms of cache attacks, their possible effects, and known mitigation measures. The study approach includes a review of current methods and their effectiveness in combating cache attack. The report also suggests future research topics for developing more effective and economical methods for …

Public Ownership And The Wto In A Post Covid-19 Era: From Trade Disputes To A 'Social' Function, Paolo Davide Farah, Davide Zoppolato

Articles

Public ownership is closely bound to the need of the government to protect and guarantee the well-being of its citizens. Where the market cannot, or does not want to, provide goods and services, the State uses different tools to intervene, influence, and control some aspects of the private sphere of expression of its citizens in the name and interest of the collectivity. Although, in the past century, this behavior was accepted as one of the expressions of the public authority and part of the social contract, this perception has shifted partially in accordance with the wave of privatization programs initiated …

Succession Of The Late Summer Phytoplankton Blooms In The York River Estuary, Va, Heather Kathleen Corson

Dissertations, Theses, and Masters Projects

The influence of bottom-up and top-down controls on the formation and persistence of phytoplankton blooms has been well studied. However, the relative importance of these bottom-up and top-down controls vary spatially and temporally. In the tidal tributaries and mainstem of Chesapeake Bay, the summer dinoflagellate population follows a succession of bloom-producing species. The dinoflagellate species Margalefidinium polykrikoides and Alexandrium monilatum are currently considered the end of this succession. These species form near-annual blooms in the lower half of Chesapeake Bay and are considered harmful algal bloom (HAB) species due to their negative ecological impacts. However, analysis of long-term monitoring data …

Comments Of The Cordell Institute On Ai Accountability, Neil M. Richards, Woodrow Hartzog, Jordan Francis

Scholarship@WashULaw

These comments are a response to the National Telecommunications and Information Administration's 2023 request for comment on AI accountability (AI Accountability RFC, NTIA–2023–0005).

Responding to NTIA’s recent inquiry into AI assurance and accountability, we offer two main arguments regarding the importance of substantive legal protections. First, a myopic focus on concepts of transparency, bias mitigation, and ethics (for which procedural compliance efforts such as audits, assessments, and certifications are proxies) is insufficient when it comes to the design and implementation of accountable AI systems. We call rules built around transparency and bias mitigation “AI half-measures,” because they provide the appearance …

Second-Harmonic Signature Of Chiral Spin Structures In W/Pt/Co Heterostructures With Tunable Magnetic Anisotropy, Yang Wang, Ying-Ting Chan, Xiao Wang, Tao Wang, Xuemei Cheng, Weida Wu, John Q. Xiao

Physics Faculty Research and Scholarship

Second-harmonic Hall voltage (SHV) measurement method has been widely used to characterize the strengths of spin–orbit torques (SOTs) in heavy metal/ferromagnet thin films saturated in the single-domain regime. Here, we show that the magnetic anisotropy of a W/Pt/Co trilayer can be robustly tuned from in-plane to out-of-plane by varying W, Pt, or Co thicknesses. Moreover, in samples with easy-cone anisotropy, SHV measurements exhibit anomalous ‘humps’ in the multidomain regime accessed by applying a nearly out-of-plane external magnetic field. These hump features can only be explained as a result of the formation of Néel-type domain walls, efficiently driven by nevertheless small …

Interfacial And Surface Magnetism In Epitaxial Nico2o4(001)/Mgal2o4 Films, Corbyn Mellinger, Xiao Wang, Arjun Subedi, Andy T. Clark, Takashi Komesu, Richard Rosenberg, Peter A. Dowben, Xuemei Cheng, Xiaoshan Xu

Physics Faculty Research and Scholarship

NiCo2O4 (NCO) films grown on MgAl2O4 (001) substrates have been studied using magnetometry, x-ray magnetic circular dichroism (XMCD) based on x-ray absorption spectroscopy, and spin-polarized inverse photoemission spectroscopy (SPIPES) with various thickness down to 1.6 nm. The magnetic behavior can be understood in terms of a layer of optimal NCO and an interfacial layer (1.2± 0.1 nm), with a small canting of magnetization at the surface. The thickness dependence of the optimal layer can be described by the finite-scaling theory with a critical exponent consistent with the high perpendicular magnetic anisotropy. The interfacial layer couples antiferromagnetically to the optimal layer, …

Bench- And Pilot-Scale Corrosion Control Inhibitor Effectiveness Studies For A Community's Blended Surficial And Brackish Groundwater Supply, Paula Campesino

Electronic Theses and Dissertations, 2020-2023

The United States Environmental Protection Agency regulates the lead and copper content of a public water system's finished water at the consumer's tap, through the Safe Drinking Water Act's Lead and Copper Rule (LCR), promulgated in 1991. This rule was recently changed through the LCR Revisions (LCRR), that took effect in 2021. The more stringent requirements of the LCRR motivated the City of Sarasota, Florida (City), to work with the University of Central Florida (UCF) on a study of the municipality's finished water corrosivity. Initially, this evaluation investigated the City's existing finished water corrosivity using linear polarization resistance (LPR) measurements …

Refining The Use Of Stable Isotope Analysis In Detecting Wildlife Laundering, Kevin Guilfoyle

Electronic Theses and Dissertations, 2020-2023

The international wildlife trade has caused significant declines in wild populations. Captive breeding can reduce the pressure on wild populations caused by overcollection, but if not properly monitored, wildlife laundering can lead to further population declines. Improving the forensic ability to detect wildlife laundering will assist in monitoring the wildlife trade and enforcing regulations, thereby aiding recovery of wild populations. Stable isotope analysis has grown in importance as a forensic tool, but improvements are needed. Here, stable isotope analysis (δ13C) on eggshells of captive bred and wild sourced island apple snails (Pomacea maculata) distinguished between the two; eggshells of captive …

High-Dynamic-Range And High-Efficiency Near-Eye Display Systems, En-Lin Hsiang

Electronic Theses and Dissertations, 2020-2023

Near-eye display systems, which project digital information directly into the human visual system, are expected to revolutionize the interface between digital information and physical world. However, the image quality of most near-eye displays is still far inferior to that of direct-view displays. Both light engine and imaging optics of near-eye display systems play important roles to the degraded image quality. In addition, near-eye displays also suffer from a relatively low optical efficiency, which severely limits the device operation time. Such an efficiency loss originates from both light engines and projection processes. This dissertation is devoted to addressing these two critical …

A Developmental Investigation Of Separation And Analysis Of Molecular Mass 302 Da Polyaromatic Hydrocarbons Using High Performance Liquid Chromatography And Chiral Stationary Phase, James Janesko

Electronic Theses and Dissertations, 2020-2023

High molecular weight – polycyclic aromatic hydrocarbons (HMW-PAH) are often found where air, water, and soil are subject to higher levels of industrial pollutants. These molecules are environmentally concerning due to their carcinogenic, mutagenic, and tumorigenic propensities. Furthermore, the isomers in this family are challenging to separate due to similar retention parameters, spectroscopic fingerprints, and mass spectral patterns. The primary purpose of this dissertation is to expand on the methodology for separation and analysis of the molecular mass 302 Da six-ring isomers using High Performance Liquid Chromatography. Retention behaviors of 21 commercially available isomers in synthetic mixture were collected via …

Error Rate Determination Of Latent Print Chemistry Via 1d And 2d Gas Chromatography, Jessica Kindell

Electronic Theses and Dissertations, 2020-2023

Latent print evidence collected from crime scenes are analyzed and compared by examiners using the ACE-V protocol (Analysis, Comparison, Evaluation-Verification) to identify potential suspects. However, smudged and poor-quality prints, usually deemed inconclusive, could be utilized for source association or discrimination based on the chemistry of the oils and sweat that comprises the latent print residue (LPR). For this research, LPRs were collected from various places on the face and analyzed via two-dimensional gas chromatography-mass spectrometry (2D GC-MS), one-dimensional (1D) GC-MS, and direct analysis in real time-high resolution mass spectrometry (DART-HRMS). LPR recovery with two common sample preparation methods, derivatization and …

Reflective Planar Optics With Cholesteric Liquid Crystal For Near-Eye Displays, Yannanqi Li

Electronic Theses and Dissertations, 2020-2023

Display market has undergone dramatic changes as the near eye displays (NED) are gaining increasing attention because they offer a deeper level of human-computer interaction with the advancement of electronic devices and computer sciences. The NEDs can be presented in two ways: virtual reality (VR) and augmented reality (AR). The former is completely immersive while the latter combines the digital information with the surrounding scenes. Although several VR headsets have been commercialized for consumers and AR products for prosumers because of their high cost, but there is still a long way to go to satisfy the strict requirements of human …

Algorithms And Variations On The Positional Burrows-Wheeler Transform And Their Applications, Ahsan Sanaullah

Electronic Theses and Dissertations, 2020-2023

In this dissertation, we develop algorithms and variations on the Positional Burrows-Wheeler Transform (PBWT). The PBWT is a data structure that stores M binary strings of length N while allowing efficient search. We develop the dynamic-PBWT (d-PBWT). The d-PBWT is a variation of the PBWT that allows its relevant algorithms to run with unchanged time complexity, but also allows efficient insertion and deletion of haplotypes. We provide insertion and deletion algorithms on the PBWT with average case O(N) time complexity. We also improve upon the query algorithms for the PBWT. Durbin described a set maximal match query algorithm on the …

Instrumental Approaches For High Resolution Photoluminescence Spectroscopy And Its Applications To Environmental Analysis, Anthony Santana

Electronic Theses and Dissertations, 2020-2023

Photoluminescence phenomena provide valuable information for the direct analysis of target chemicals in complex samples. To take full advantage of the information content of fluorescence and phosphorescence phenomena, the analyst should have access to instrumentation capable to record data formats in the wavelength and time domains. Previous efforts in our lab have developed laser-based instrumentation to combine spectral and lifetime information into data formats known as wavelength time matrices (WTMs) and time-resolved excitation emission matrices (TREEMs). Recording WTMs during the emission decay of the sample makes it possible to unambiguously identify chemicals on the bases of spectral and lifetime information. …

Integrated Frequency Combs For Applications In Optical Communications & Microwave Photonics, Chinmay Shirpurkar

Electronic Theses and Dissertations, 2020-2023

This dissertation reviews the advancements made in chip-scale optical frequency combs and their applications towards optical communications and optical to RF links. We review different chip-scale comb sources and in particular, chip-scale Kerr microresonator frequency combs. Then, we establish the theoretical background in nonlinear optics which allows the formation and stabilization of Kerr solitons in nonlinear cavities. We also discuss the concept of optical injection locking and in particular, multi-tone injection locking which precedes the idea of regenerative harmonic injection locking. We then go on to show the experimental work involved in soliton generation and characterization. We show efforts towards …

Development Of Regolith Simulants Of Lunar Permanently Shadowed Regions And Jupiter Trojan Asteroids, Karlis Slumba

Electronic Theses and Dissertations, 2020-2023

Every scientific experiment or innovation goes through a phase of testing equipment. This is not only true for experiments in the laboratory, but also very relevant for experiments on other planetary bodies. In order to test tools and robotic equipment that are destined for another planet, moon, asteroid or comet, it is necessary to simulate the regolith environment on that surface. In this thesis we have provided an overview of two methods for regolith simulant development. In one approach we made simulants in different compositions to find the best spectral fit to Jupiter Trojan asteroids. At visible to near-infrared (VNIR) …

Improving Deep Neural Network Training With Knowledge Distillation, Dongdong Wang

Electronic Theses and Dissertations, 2020-2023

Knowledge distillation, as a popular compression technique, has been widely used to reduce deep neural network (DNN) size for a variety of applications. However, in recent years, some research had found its potential for improving deep neural network performance. This dissertation focuses on further exploring its power to facilitate accurate and reliable DNN training. First, I explored data-efficient method for blackbox knowledge distillation where the specifics of the DNN for distillation is inaccessible. I integrated active learning and mixup to obtain significant distillation performance gain with limited data. This work reveals the competence of knowledge distillation to facilitate large foundation …

Automated Machine Learning: Intellient Binning Data Preparation And Regularized Regression Classfier, Jianbin Zhu

Electronic Theses and Dissertations, 2020-2023

Automated machine learning (AutoML) has become a new trend which is the process of automating the complete pipeline from the raw dataset to the development of machine learning model. It not only can relief data scientists' works but also allows non-experts to finish the jobs without solid knowledge and understanding of statistical inference and machine learning. One limitation of AutoML framework is the data quality differs significantly batch by batch. Consequently, fitted model quality for some batches of data can be very poor due to distribution shift for some numerical predictors. In this dissertation, we develop an intelligent binning to …

Compact And High Optical Efficiency Near-Eye Displays With Liquid Crystal Flat Optics, Junyu Zou

Electronic Theses and Dissertations, 2020-2023

Since the concepts of augmented reality (AR) and virtual reality (VR) were introduced, they have attracted people's attention worldwide, both in the industry and research areas. As the most promising hardware architecture that can bring AR/VR into daily life, near eye displays (NEDs) have been studied and investigated heavily over the past half-century, especially the concept of "Metaverse" introduced by some top companies in recent years. However, the form factor and optical efficiency are two major bottlenecks for the current NEDs before they can become the major platform. Liquid crystal (LC) flat optics have several advantages, including compact, high diffraction …

Physical Properties And Chemical Composition Of Comets, Olga Harrington

Electronic Theses and Dissertations, 2020-2023

Comets and Centaurs are icy remnants from the formation of the solar system. Analyzing the physical properties of their nuclei and their production rates can serve as powerful tools for tracing primitive solar system material. The four research projects in this dissertation examine these properties in comets and Centaurs. The first project focuses on observations of main belt comet 176P/LINEAR that were obtained with the Kepler space telescope. Optical lightcurves were used to constrain models of the nucleus's spin pole axis, shape and activity level. The second project used millimeter-wavelength spectra from the Arizona Radio Observatory Submillimeter Telescope and infrared …

Towards Optimization And Robustification Of Data-Driven Models, Ehsan Kazemi Foroushani

Electronic Theses and Dissertations, 2020-2023

In the past two decades, data-driven models have experienced a renaissance, with notable success achieved through the use of models such as deep neural networks (DNNs) in various applications. However, complete reliance on intelligent machine learning systems is still a distant dream. Nevertheless, the initial success of data-driven approaches presents a promising path for building trustworthy data-oriented models. This thesis aims to take a few steps toward improving the performance of existing data-driven frameworks in both the training and testing phases. Specifically, we focus on several key questions: 1) How to efficiently design optimization methods for learning algorithms that can …

Methodologies For Evaluating Interaction Cues For Virtual Reality, Xinyu Hu

Electronic Theses and Dissertations, 2020-2023

Virtual reality (VR) games and educational systems commonly employ interaction cues to provide information on how to take appropriate actions at particular moments. Interaction cues can be employed for different purposes, such as informing the user to look, go, pick, and operate. Additionally, different types of interaction cues can directly affect usability and user experiences. In our early research, we conducted two ecologically valid empirical studies with a preexisting VR training application and evaluated the effects of delayed interaction cues, in addition to comparing the purposes of interaction cues for learning and retention. Our results indicated that immediate interaction cues …

The Discovery And Characterization Of Novel Potent 5-Substituted 3, 3’, 4’, 7-Tetramethoxyflavonoid Dna Triplex Specific Binding Ligands, Vanessa Marie Rangel

University of the Pacific Theses and Dissertations

Chemotherapy works by killing fast dividing cells. Unfortunately, these drugs are not specific to cancer tissue and can damage normal cells. Chemotherapy is like taking poison and hoping it kills the cancer cells before it kills you. As an alternative, many researchers have investigated the use of antigene therapy to selectively target cancer causing genes to avoid off target effects. Although promising, the theory is limited by the stability of the triplex structure. Here, we report the discovery of potent triplex binding ligands derived from the natural product quercetin. Chemical derivatives of 5-substituted 3, 3’, 4’, 7-tetramethoxyquercetin derivatives were characterized …

Artificial Emotional Intelligence In Socially Assistive Robots, Hojjat Abdollahi

Electronic Theses and Dissertations

Artificial Emotional Intelligence (AEI) bridges the gap between humans and machines by demonstrating empathy and affection towards each other. This is achieved by evaluating the emotional state of human users, adapting the machine’s behavior to them, and hence giving an appropriate response to those emotions. AEI is part of a larger field of studies called Affective Computing. Affective computing is the integration of artificial intelligence, psychology, robotics, biometrics, and many more fields of study. The main component in AEI and affective computing is emotion, and how we can utilize emotion to create a more natural and productive relationship between humans …

Water Literacy In Drought-Prone Regions: Case Studies From Aurora, Colorado, Usa And Cape Town, Western Cape, South Africa, Meghan Mccarroll

Electronic Theses and Dissertations

Water managers around the world must reevaluate their approach to water security as challenges continue to grow. Supply-focused paradigms that aimed to capture, control, and commodify water resources are increasingly unreliable and often depend on environmentally and socially damaging practices. Of particular concern are regions experiencing climate shocks and aridification from rising global temperatures. In order to stretch limited water resources using equitable water policies, conservation programs, and alternative water sourcing, water managers must invest in a water literate citizenry. Water literacy is the culmination of water-related knowledge, attitudes, and behaviors. The benefits of a water literate citizenry abound, including …

Dormant Propagules In Demographic Studies: A Recurrent Bias And Potential Solutions, Federico Borghesi

Graduate Thesis and Dissertation 2023-2024

In the face of unprecedented anthropogenic change, we increasingly turn to emergent technologies and extensive data sets for solutions that complement much needed systemic changes in our societies. These technological solutions, however, must be approached with care. We must recognize and address biases in the way data has been accumulated. In demographic studies, dormant life stages, such as seed banks, and other cryptic factors have often been neglected. The potential consequences of these omissions have been extensively described in the literature. In the first chapter, I analyze patterns of seed bank omissions in demographic models, finding unjustified omissions are widespread …

Multi-Kilowatt Fiber Laser Amplifiers And Hollow-Core Delivery Fibers, Matthew Cooper

Graduate Thesis and Dissertation 2023-2024

High-power fiber lasers have emerged as a cornerstone in the realm of laser technology. Characterized by their exceptional efficiency, ruggedness, and versatility, fiber lasers are experiencing widespread use in manufacturing, medical, defense, science, and in long range sensing. Unfortunately, high-power applications require strict spatial and spectral performance characteristics to be maintained, which has yet to be perfected.

This dissertation discusses the power scaling of ytterbium-doped fiber laser amplifiers, presenting three significant advancements. First, a novel photonic lantern-based method is introduced for real-time monitoring of laser beam modal content and beam quality. Initial tests highlight the photonic lantern's efficiency in predicting …