Physical Sciences and Mathematics Commons^™

Nutrient Restoration Of A Large, Impounded, Ultra-Oligotrophic Western River To Recover Declining Native Fishes, Ryan S. Hardy, Tyler J. Ross, Kevin N. Mcdonnell, Michael C. Quist, Charlie Holderman, Bryan S. Stevens

United States Geological Survey: Staff Publications

Declines in many fish populations in large, western rivers have been primarily attributed to the anthropogenic reduction of nutrient inputs and subsequent impacts to the food web. The largest known river fertilization program was implemented starting in 2005 on the Kootenai River in northern Idaho to restore resident fisheries. Annual electrofishing surveys were conducted at multiple sites in Idaho and Montana before and during nutrient addition to evaluate assemblage and population-level responses. Although few responses in fish assemblage structure were observed, the addition of liquid ammonium polyphosphate fertilizer (3 μg/L) to the Kootenai River increased fish abundance and biomass over …

One-Step Synthesis Of Corn Oil-Based Polyol For Highly Flame-Retardant Rigid Polyurethane Foams, Tenzin Ingsel

Electronic Theses & Dissertations

Rigid polyurethane foams (RPUF), heavily utilized in construction, refrigeration, and the automotive industries, are a significant class of polyurethanes. They can substantially enhance energy efficiency by improving thermal insulation. However, the application of petrochemical sources in polyurethane has raised environmental concerns.

Such concerns call for the development and application of new bio-based polyurethanes to potentially reduce humanity's over-reliance on nonrenewable sources.

In this work, corn oil-based polyol was synthesized via popularized thiol-ene reaction. The obtained polyol was characterized by wet chemistry methods, spectroscopic evaluations, and chromatography. Non-halogenated flame retardants of cost-effective and environmentally friendly nature were incorporated into the polyurethane …

Transistion Metal Chalcogenides And Phosphides For Energy Storage And Conversion Through Water Splitting, Kelsey Thompson

Electronic Theses & Dissertations

In contemporary society, there are many different ways that energy is used in daily life. From applications that require a high energy density to long-term storage in a stable manner, the requirements for energy usage are diverse. Therefore, the greater the number of uses a designed material exhibits, the more practical it may be for wide-scale manufacture. Two areas of particular interest for energy applications are fuel cells (to generate energy) and supercapacitors (to store energy). To provide cheaper and more durable alternatives for energy storage, electrodes containing CoMoO₄, NiMoO₄, CoMoS₄, NiMoS₄, …

An Interdisciplinary Approach To Understanding Volcanoes And Their Processes, Katherine Cosburn

Physics & Astronomy ETDs

To better understand volcanoes and their processes is important from both a fundamental science perspective and for hazard monitoring purposes. The complexity and limitations we face in pursuing such a science are numerous and this dissertation explores how an interdisciplinary approach combining physics, computer science, and volcanology can address this complexity in a straightforward and meaningful way. This is achieved through various modelling techniques across three studies: (1) a first-order analytic modelling of stratovolcano topographic shape, (2) the use of a Bayesian joint inversion on gravity and novel cosmic-ray muon measurements for imaging flat-lying subsurface density anomalies, and (3) the …

Nonequilibrium And Nonlinear Dynamics In Collective Spin Models And Implementations Using Quantum Feedback Control, Manuel H. Munoz Arias

Physics & Astronomy ETDs

Out-of-equilibrium dynamics generalizes the study of ground states of quantum Hamiltonians at zero temperature, to that of dynamical quasi-steady states of quantum systems far from equilibrium. In this dissertation I discuss dynamical quantum phase transitions and out-of-equilibrium phases of matter in models of collective spins with multi-body interactions. These models, based on collective degrees of freedom, allow an exact description of the thermodynamic limit via the mean-field description. In this limit, the nonequilibrium dynamics of properties of quantum states is mapped to the nonlinear dynamics of classical variables, and thus it can be analyzed using tools from the theory of …

Examination Of Ionization In Cesium Diode Pumped Alkali Lasers With An Ion Chamber Diagnostic, Benjamin Oliker

Optical Science and Engineering ETDs

Diode pumped alkali lasers (DPALs) are leading candidates for future high power applications, with many potential utilities for the military, aerospace, communications, and scientific diagnostics. A critical step in their development is measurement and understanding of unwanted ionization processes that occur inside the laser, which decrease efficiency, reduce the usable alkali population, and increase heat load. In this dissertation, direct measurement of the ionization rate of a cesium DPAL gain medium are made for the first time, via application of an ion chamber diagnostic. Results will demonstrate that the rate of ionization is slow compared to pump absorption, with a …

Political Corruption And Corporate Risk-Taking, Hinh Khieu, Nam H. Nguyen, Hieu V. Phan, Jon A. Fulkerson

School of Mathematical & Statistical Sciences Faculty Publications

We use variation in corruption convictions across judicial districts in the US to examine the relationship between political corruption and risk-taking of public firms. Firms headquartered in regions with high levels of political corruption have lower total risk and lower idiosyncratic risk on average. Further analysis shows that corruption tends to encourage firms to pursue risk-decreasing investments, lower the riskiness of their operations, and decrease asset liquidity. While managerial ownership is intended to align the interests of managers and shareholders, the presence of corruption appears to encourage undiversified managers to decrease risk-taking. Our evidence is consistent with agency theory and …

On Two-Player Pebbling, Garth Isaak, Matthew Prudente, Andrea Potylycki, William Fagley, Joseph Marcinik

Communications on Number Theory and Combinatorial Theory

Graph pebbling can be extended to a two-player game on a graph G, called Two-Player Graph Pebbling, with players Mover and Defender. The players each use pebbling moves, the act of removing two pebbles from one vertex and placing one of the pebbles on an adjacent vertex, to win. Mover wins if they can place a pebble on a specified vertex. Defender wins if the specified vertex is pebble-free and there are no more pebbling moves on the vertices of G. The Two-Player Pebbling Number of a graph G, η(G), is the minimum m such that for every arrangement …

Understanding The Influence Of Perceptual Noise On Visual Flanker Effects Through Bayesian Model Fitting, Jordan Deakin, Dietmar Heinke

MODVIS Workshop

No abstract provided.

The Fierce Green Fire: Vol. 12 Issue 18, Wofford College. Department Of Environmental Studies

The Fierce Green Fire

No abstract provided.

Low-Temperature Luminescence Spectrum Of A Fine-Grained Cdte Layer In A Film Heterostructure N-Cds/P-Cdte, N. Kh Yuldashev

Scientific-technical journal

It is shown that the spectrum of low-temperature (4.2 K) edge photoluminescence of a thin and fine-grained (h,d=1mkm) polycrystalline CdTe layer in an n-CdS/p-CdTe film heterostructure upon frontal excitation by an Ar+ laser with a flux power of -4.8 mW/mm² consists of the dominant А - lines of intrinsic (e-h) emission with a half-width6-8 meV and a short-wavelength shift 30 meV of the red boundary relative to Eg , its LO-phonon repetition (B-lines, 40meV) and a broad D-line (40 meV) of surface-interface luminescence with a maximum at a frequency of 150eV. The back illumination of the photoresistive CdS layer …

The Baltimore Oriole’S Nest: Cool Winds From The Inner And Outer Parts Of A Star-Forming Galaxy At Z=1.3, Weichen Wang, Susan A. Kassin, S. M. Faber, David C. Koo, Emily C. Cunningham, Hassen M. Yesuf, Guillermo Barro, Puragra Guhathakurta, Benjamin J. Weiner, Alexander De La Vega, Yicheng Guo, Timothy M. Heckman, Camilla Pacifici, Bingjie Wang, Charlotte Welker

Pacific Faculty Work

Strong galactic winds are ubiquitous at z ≳ 1. However, it is not well-known where inside galaxies these winds are launched from. We study the cool winds (∼10⁴ K) in two spatial regions of a massive galaxy at z = 1.3, which we nickname the “Baltimore Oriole’s Nest.” The galaxy has a stellar mass of 10^10.3±^0.3Me, is located on the star-forming main sequence, and has a morphology indicative of a recent merger. Gas kinematics indicate a dynamically complex system with velocity gradients ranging from 0 to 60 km s⁻¹. The two regions studied …

Small Business Cybersecurity: A Loophole To Consumer Data, Matthew R. Espinosa

The Scholar: St. Mary's Law Review on Race and Social Justice

Small businesses and small minority owned businesses are vital to our nation’s economy; therefore legislation, regulation, and policy has been created in order to assist them in overcoming their economic stability issues and ensure they continue to serve the communities that rely on them. However, there is not a focus on regulating nor assisting small businesses to ensure their cybersecurity standards are up to par despite them increasingly becoming a victim of cyberattacks that yield high consequences. The external oversight and assistance is necessary for small businesses due to their lack of knowledge in implementing effective cybersecurity policies, the fiscal …

The Contribution Of Ethical Governance Of Artificial Intelligence & Machine Learning In Healthcare, Tina Nguyen

Electronic Theses and Dissertations

With the Internet Age and technology progressively advancing every year, the usage of Artificial Intelligence (AI) along with Machine Learning (ML) algorithms has only increased since its introduction to society. Specifically, in the healthcare field, AI/ML has proven to its end-users how beneficial its assistance has been. However, despite its effectiveness and efficiencies, AI/ML has also been under scrutiny due to its unethical outcomes. As a result of this, two polarizing views are typically debated when discussing AI/ML. One side believes that AI/ML usage should continue regardless of its unsureness, while the other side argues that this technology is too …

Biomaterials: From Scaffold Design To Implant Optimization, Jennifer Marie Armen

Electronic Theses and Dissertations

This work encompasses three individual projects concerning biomaterials and their modifications. Chemically-Induced Cross-Linking of Peptidic Fibrils for Scaffolding Polymeric Particles and Macrophages EAK16-II (EAK) is a self-assembling peptide (SAP) that forms β-sheets and βfibrils through ionic-complementary interactions at physiological ionic strengths. The soft materials can be injected in vivo, creating depots of drugs and cells for rendering pharmacological and biological actions. The scope of the applications of EAK is sought to extend to tissues through which the flow of extracellular fluid tends to be limited. In such anatomical locales the rate and extent of the fibrilization are limited insofar as …

Turbulent Transport Of Dissolved Oxygen In Natural Channels, Alanna Bachtlin

Electronic Theses and Dissertations

The transport and mixing of dissolved oxygen (DO) is important to replenish the oxygen depleted by natural processes; gas transfer in general has implications for ecosystem metabolism and greenhouse gas transfer. Currently, reaeration coefficients can be found through gas tracer methods, which estimates one-way gas transfer. For this project, a net oxygen consumption rate, , was developed using the similarity equations, which provides a value from DO and velocity profiles specific to a stream site. Additionally, three models to calculate friction velocity, which is required for oxygen consumption rate, were compared. Reynolds stresses, mathematically developed in the Reynolds-Averaged Navier-Stokes Equations, …

Advancing Towards A More Complete Sign Language Detection Application, Shane Angel

Undergraduate University Honors Capstones

The goal of this capstone is to improve the experiences of Deaf and Hard of Hearing individuals who use teleconferencing tools through the use of sign language detection software. Popular teleconferencing applications such as Zoom and Google Meet contain features that can automatically spotlight users when they are speaking, but there is currently no equivalent feature for those who used signed languages to communicate on these platforms. Such a feature would need to utilize a sign language detection program to spotlight individuals, but this technology is early in development and is not currently available for large-scale implementation. This capstone strives …

Graph-Based Unsupervised Entity Resolution For Identifying Entity Profiles In Ambiguous Data, Islam Akef Ebeid

Theses and Dissertations

Entity resolution means finding duplicate records within the same table, across various tables, or in multiple databases. Traditional and rule-based approaches in entity resolution rely on handcrafting rules for matching records. On the other hand, machine learning and deep learning methods are data-intensive and require labeled training datasets. Thus the move toward automating entity resolution for data cleaning, curation, and integration has become the goal for many organizations. Accordingly, unsupervised entity resolution methods have proliferated, relying on an automated pipeline of preprocessing, blocking, feature extraction, matching, clustering, profiling, and canonicalization. Unsupervised entity resolution methods face many challenges due to the …

Circular Economy And The Potential For Extended Producer Responsibility Policies, Erin Quinn

Senior Honors Projects, 2020-current

This thesis was developed based on an Extended Producer Responsibility (EPR) Policy briefing I created during my internship at RISE (Responsible Industry for a Sound Environment) during the summer of 2021. This project expands upon the work created during the internship. It examines the connection between circular economy and EPR policies, as well as how they can create effective strategies for waste reduction and recycling in the U.S. It demonstrates how the current linear economic system under which the U.S operates and its connection to single-stream recycling are inefficient at best. The thesis then describes how a circular economy (CE) …

A Quantitative Study Of An Online Learning Platform’S Impact On High School Students' Engagement, Academic Achievement, And Student Satisfaction In A Mathematics Class, Mariah Minkkinen

Dissertations, Theses, and Projects

The present study investigated the impact using the online learning platform Pear Deck had on an online high school math class. The study measured student engagement, academic achievement, and students’ overall satisfaction with using the online learning platform. The participants in this study were online Algebra 2 students. The study was conducted during synchronous online lessons using an online learning system. Data was collected from two different live classes. One class used the online learning platform Pear Deck and the other did not. Engagement was measured by charting the number of student responses for each question posed. Students’ academic achievement …

A Priori And A Posteriori Error Estimates For The Quad-Curl Eigenvalue Problem, Lixiu Wang, Qian Zhang, Jiguang Sun, Zhimin Zhang

Michigan Tech Publications, Part 1

In this paper, we consider a priori and a posteriori error estimates of the H(curl²)-conforming finite element when solving the quad-curl eigenvalue problem. An a priori estimate of eigenvalues with convergence order 2(s − 1) is obtained if the corresponding eigenvector u ∈ H^{s − 1}(Ω) and ∇ × u ∈ H^s(Ω). For the a posteriori estimate, by analyzing the associated source problem, we obtain lower and upper bounds for the errors of eigenvectors in the energy norm and upper bounds for the errors of eigenvalues. Numerical examples are presented for validation.

Scalable Deeper Graph Neural Networks For High-Performance Materials Property Prediction, Sadman Sadeed Omee, Steph-Yves Louis, Nihang Fu, Lai Wei, Sourin Dey, Rongzhi Dong, Qinyang Li, Jianjun Hu

Faculty Publications

Machine-learning-based materials property prediction models have emerged as a promising approach for new materials discovery, among which the graph neural networks (GNNs) have shown the best performance due to their capability to learn high-level features from crystal structures. However, existing GNN models suffer from their lack of scalability, high hyperparameter tuning complexity, and constrained performance due to over-smoothing. We propose a scalable global graph attention neural network model DeeperGATGNN with differentiable group normalization (DGN) and skip connections for high-performance materials property prediction. Our systematic benchmark studies show that our model achieves the state-of-the-art prediction results on five out of six …

A Modular Synthesis Of Processable And Thermally Stable Semi-Fluorinated Aryl Ether Polymers Via Step-Growth Polymerization Of Fluoroalkenes, Ketki Eknath Shelar

Theses and Dissertations

Tailored fluoropolymers remain the leading choice for a wide variety of advanced high-performance applications, including electronic/optical and energy conversion, owing to their unique blend of complementary high-performance properties. Amorphous semi-fluorinated polymers exhibit improved solubility and melt processability when compared to traditional perfluoropolymers. A leading class of semi-fluorinated aryl ether polymers includes perfluorocyclobutyl (PFCB), perfluorocycloalkenyl (PFCA), and fluoroarylene vinylene ether (FAVE) polymers. Monomers containing aromatic trifluorovinyl ethers (TFVE) are used to synthesize PFCB polymers via radical-mediated [2+2] cyclodimerization. On the other hand, FAVE and PFCA polymers are polymerized via base-mediated nucleophilic addition/elimination of bisphenols with TFVE monomers and decafluorocyclohexene respectively. The …

Evaluating Soil Health Changes Following Cover Crop And No-Till Integration Into A Soybean (Glycine Max) Cropping System In The Mississippi Alluvial Valley, Alexandra Gwin Firth

Theses and Dissertations

The transition of natural landscapes to intensive agricultural uses has resulted in severe loss of soil organic carbon (SOC), increased CO₂ emissions, river depletion, and groundwater overdraft. Despite negative documented effects of agricultural land use (i.e., soil erosion, nutrient runoff) on critical natural resources (i.e., water, soil), food production must increase to meet the demands of a rising human population. Given the environmental and agricultural productivity concerns of intensely managed soils, it is critical to implement conservation practices that mitigate the negative effects of crop production and enhance environmental integrity. In the Mississippi Alluvial Valley (MAV) region of Mississippi, USA, …

Cover Crops And Irrigation Impacts On Corn And Soybean Production In The Mid-Southern Usa, Dillon Aaron Russell

Theses and Dissertations

Reducing groundwater withdrawals from the Mississippi River Valley Alluvial Aquifer is imperative to sustain future irrigated cropping systems in the mid-southern USA. This research was conducted to determine the impacts of cover crops and irrigation sensor thresholds on corn (Zea mays L.) and soybean (Glycine max L.) production, water productivity, irrigation water use efficiency, and soil physical properties in the Mississippi Delta. The cover crop treatments included cereal rye (Secale cereale L.), hairy vetch (Vicia villosa R.), wheat (Triticum aestivum L.)-radish (Raphanus sativus L.)-turnip (Brassica rapa L.) mix, and no cover crop. The irrigation thresholds included -40 kPa, -90 kPa, …

Insights Into Molecular Recognition And Reactivity From Molecular Simulations Of Protein-Ligand Interactions Using Md And Qm/Mm, Jerrano L. Bowleg

Theses and Dissertations

In this thesis, we have employed two computational methods, molecular dynamics (MD) and hybrid quantum mechanics/molecular mechanics (QM/MM) MD simulations with umbrella sampling (US), to gain insights into the molecular mechanism governing the molecular recognition and reactivity in several protein-ligand complexes. Three systems involving protein-ligand interactions are examined in this dissertation utilizing well-established computational methodologies and mathematical modeling. The three proteins studied here are acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (PIN1). These enzymes are known to interact with a variety of ligands. AChE dysfunction caused by organophosphorus (OP) chemicals is a severe hazard since AChE is …

Synthesis Of Conjugated Polymers From Xanthene And Alkenyl Flanked Diketopyrrolopyrrole Monomers For High-Performance Electronic Applications., Ranganath Wijesinghe Wahalathantrige Don

Theses and Dissertations

In traditional electronics, inorganic materials such as silicon and germanium are used as semiconductors due to their outstanding semiconducting properties. Unfortunately, inorganic materials are rigid due to their high crystalline nature, and processing these materials is complex and expensive. Furthermore, traditional semiconducting materials do not have favorable mechanical properties in applications such as wearable devices and large-area applications with complicated shapes. Conjugated conducting polymers (CCPs) are being explored as alternative materials to conventional semiconductors due to their mechanical properties and high conductivity. CCPs offer properties such as solution and low-temperature processability, flexibility, thermal and optical properties that traditional semiconductors could …

Functionalized Biochar Electrodes For Asymmetric Capacitive Deionization, Hellen Stephanie

Theses and Dissertations

Electrosorption-based capacitive deionization (CDI) has become a viable process for brackish water desalination and defluoridation. In this study, activated Douglas fir biochar is used as a low-cost electrode material with adsorption capacity comparable to activated carbon obtained from biomass precursors. Adding functional groups to the activated biochar enhanced salt removal capacity, providing cation and anion selectivity. The functionalized electrodes were prepared by Nafion, titanium isopropoxide, and p-phenylenediamine treatment, respectively, which introduced sulfonate, titanium dioxide and amine functional groups to the electrode surface. These modification methods are versatile and can be easily performed without sophisticated laboratory environment. Modified biochar electrodes …

Structural And Biological Analysis Of Faults In Basalts In Sheepshead Mountains, Oregon As An Earth Analogue To Mars, Allison Bohanon

Theses and Dissertations

Microbial life on Mars is not visible from orbit or by rover cameras, but the fracture networks and scarp morphologies associated with fractures they could live in are measurable. We conducted a field analogue study of 92 normal fault scarps in the Sheepshead Mountains, Oregon to examine the correlation between scarp morphology and vegetation growth in the Steens Basalt. While vegetation is not expected on Mars, the fracture networks that sustain vegetation offer the same micro-environment that would support and protect endoliths. Structural variables were measured in the field and infrared spectra of fault scarps were measured using a handheld …

Rooted In The Earth: An Igbo Sacramental Nature Of The Universe, A Model For Igbo Christian Ecological Ethics, Kenneth Oguzie

Electronic Theses and Dissertations

The contemporary Igbo society faces a lot of challenges. These include political, religious, and moral crises. These crises affect the environment in many ways. They threaten the peace and harmony of the Igbo society. As a result, it touches on faith. The Igbo society holds a holistic view of life. Whatever affects one aspect of life affects the other areas. Ecologically, various factors are responsible for the crises. These include changes in lifestyle from the traditional way of living to modern style of life with its penchant on consumerism. Also, colonialism and its lingering residues, civil unrests, politics, population growth, …