Physical Sciences and Mathematics Commons^™

Sensitivity Of Radical Sam Enzyme Mftc To Molecular Oxygen, Vishnu Govindarajan

Electronic Theses and Dissertations

MftC is a radical S-adenosyl L-methionine (SAM) enzyme that catalyzes the first step in the production of mycofactocin. It is a ribosomally synthesized post-translationally modified (RiPP) redox cofactor shown to be essential for the survival of bacteria in the Mycobacterium genus in the presence of cholesterol as a carbon source and for the sequestration of ethanol. MftC catalyzes the C – terminal decarboxylation of tyrosine and the subsequent cross-linking of tyrosine to the penultimate valine on the precursor peptide MftA. The product formed out of the reaction is processed into mycofactocin in downstream processes. The bacteria in the Mycobacterium tuberculosis …

Predicting Student Sustainability Knowledge, Attitudes, And Behaviors: Effects Of Demography, Environmental Science Education, And Sustainability Intervention Programs At Georgia Southern University, Bailey Chandler

Electronic Theses and Dissertations

This mixed-methods research approach assesses trends in sustainability knowledge, attitudes, and behaviors in the student population at Georgia Southern University (GS). Students completed a baseline survey in order to determine their knowledge and attitudes about sustainability and what sustainable behaviors they perform. A total of 1,328 useable responses to the baseline survey were gathered. Effects of race, academic class, gender, and prior completion of an environmental science course were tested, as well as the effect of campus (Statesboro and Armstrong). Previously taking an environmental science course and race/ethnicity were the two strongest indicators of knowledge score. Males scored higher than …

A Spectropolarimetric Study Of Southern Wr + O Binaries, Andrew G. Fullard

Electronic Theses and Dissertations

The classical Wolf-Rayet (WR) state is the evolved stage of a massive star, post main-sequence. They are characterized by their strong emission line spectra and stellar winds that are often more than 10 times denser than that of their progenitor O-type stars, which have mass loss rates of 10^-6 M_Θyr^-1. The evolution of WR stars and their connection to specific types of supernovae (SNe) is an open question. Current theory suggests that rapidly rotating massive stars may be the progenitors of SNe that produce long-duration gamma-ray bursts. The interaction between WR stars and their companion …

Examining Artifacts Of The Watershed Segmentation, Emily Jo Armitage

Electronic Theses and Dissertations

The watershed segmentation is an algorithm used to systematically track cell intercalary behaviors during germ band extension of the Drosophila embryo. Neighboring cells share a contracting vertical interface, called a T1, which continues contracting to a single point, a T2, and extending in the horizontal direction to create what is called a T3 interface (Fig. 1). Additionally, higher order vertices called rosettes occur when five or more cells meet at a common vertex. Simulated T2 events demonstrate that cell angle and not noise level in the image contributes to the incorrect detection of artifactual T1s in more acute angled cells …

2d Confinement Of Thermal Gradients In Metallic Non-Local Spin Valves, Rachel K. Bennet

Electronic Theses and Dissertations

Non-local spin valves (NLSVs) are a valuable tool in the growing field of spintronics due to their unique ability to separate charge current from pure spin current. Their potential applications as read heads for hard-disk drives, as well as use as logic gates and other spin sensors, makes detailed understanding of their behavior under a wide range of operating conditions very important.

In this dissertation, I present results of extreme thermal engineering of the supporting substrate of NLSVs, which has a dramatic impact on the background signal of the device as well as contributions from thermal spin effects such as …

Assessing Robustness Of The Rasch Mixture Model To Detect Differential Item Functioning - A Monte Carlo Simulation Study, Jinjin Huang

Electronic Theses and Dissertations

Measurement invariance is crucial for an effective and valid measure of a construct. Invariance holds when the latent trait varies consistently across subgroups; in other words, the mean differences among subgroups are only due to true latent ability differences. Differential item functioning (DIF) occurs when measurement invariance is violated. There are two kinds of traditional tools for DIF detection: non-parametric methods and parametric methods. Mantel Haenszel (MH), SIBTEST, and standardization are examples of non-parametric DIF detection methods. The majority of parametric DIF detection methods are item response theory (IRT) based. Both non-parametric methods and parametric methods compare differences among subgroups …

Investigating New Methods To Develop Perovskite Solar Cells, Amani Hussain Alfaifi

Electronic Theses and Dissertations

Discovering the potential of organic-inorganic metal halide perovskites (MHP) as a harvesting material in solar cells has strongly affected the research direction in solar energy. The fascinating optical and electronic properties offered by MHP combined with tremendous effort from scientists around the world have improved the efficiency to about 25% in a decade.

In the first part of the dissertation, we studied the lamination process as a new fabrication method for producing self-encapsulated perovskite solar cells based on laminating half stacks,as opposed to the conventional layer-by-layer method. Our work focused on optimizing the lamination process of complex triple cations perovskite …

Rock Glacier Development In The San Juan Mountains, Brandon K. Bailey

Electronic Theses and Dissertations

Rock glaciers are common landform features found in deglaciated alpine areas. They are commonly used in the study of climatic changes throughout the Holocene and the reconstruction of neoglacial chronologies. For this research, Schmidt hammer rebound values, weathering rind thicknesses, and the length of lichen thalli diameters found on rock glacier surfaces are used to investigate their effectiveness as field-based relative age determination techniques. Additionally, the ability to identify periods of neoglacial activity using these methods is assessed in two neighboring cirque basins in the San Juan Mountains of Colorado. 41 field sites across three rock glaciers are established with …

Certification-Driven Testing Of Safety-Critical Systems, Aiman S. Gannous

Electronic Theses and Dissertations

Safety-critical systems are those systems that when they fail they could cause loss of life or significant physical damages. Since software now is an essential component of these types of systems, failures caused by software faults could come from flaws in the software development life-cycle. As a result, challenges unfold in two directions. First, in verifying that the software will not put the system in an unsafe state, and identifying external failures and mitigate them properly. Second, in providing sufficient evidence for an efficient safety certification process. In this study, we propose an approach for testing safety-critical systems called Model-Combinatorial …

Experiments On The Neural Network Approach To The Handwritten Digit Classification Problem, William Meissner

Electronic Theses and Dissertations

When the MNIST dataset was introduced in 1998, training a network was a multiple week problem in order to receive results far less accurate than an average CPU can produce within a couple of hours today. While this indicates that training a network on such a dataset is not the complicated problem it may have been twenty years ago, the MNIST dataset makes a good tool for study and testing with beginner and medium complexity neural networks. This paper follows along with the work presented in the online textbook “Neural Networks and Deep Learning” by Michael Nielson and an updated …

Automatic Target Recognition With Deep Metric Learning., Abdelhamid Bouzid

Electronic Theses and Dissertations

An Automatic Target Recognizer (ATR) is a real or near-real time understanding system where its input (images, signals) are obtained from sensors and its output is the detected and recognized target. ATR is an important task in many civilian and military computer vision applications. The used sensors, such as infrared (IR) imagery, enlarge our knowledge of the surrounding environment, especially at night as they provide continuous surveillance. However, ATR based on IR faces major challenges such as meteorological conditions, scale and viewpoint invariance. In this thesis, we propose solutions that are based on Deep Metric Learning (DML). DML is a …

Gas Adsorption In Carbon Nanohorns: Equilibrium And Kinetics, Justin Matthew Petucci

Electronic Theses and Dissertations

A study of gas adsorption has been carried out with the focus of better understanding the relationships between the individual properties of the adsorbent/adsorbate (e.g. material structure, interactions, gas size and shape, etc.) and the overall adsorptive properties of the combined system (e.g. capacity, binding strength, equilibration time, etc.) as a function of thermodynamical variables. This is useful from the perspective of a comprehensive and fundamental understanding as well as for practical applications. The equilibrium regime of adsorption on carbon nanostructure materials (nanohorns, nanotubes, and graphite) is investigated using molecular statics (MS) and grand canonical monte carlo (GCMC) methods for …

The Effects Of Adverse Childhood Experiences On Behavioral Outcomes, Jennifer Thomas

Electronic Theses and Dissertations

This study intends to explore the intersection of two vulnerable populations, early childhood development and risks associated with exposure to adverse childhood experiences (ACEs). This study examines how age plays a role in the long-term relationship between ACEs and internal and external behaviors. This study seeks to answer the question of: How does age influence the relationship between number of ACEs and internal and external behaviors? The participants in this study include those aged 0 – 16 from the National Survey of Child and adolescent Well-Being (NSCAW) dataset. The NSCAW study consists of five waves of data where Wave I …

Automated Recognition Of Facial Affect Using Deep Neural Networks, Behzad Hasani

Electronic Theses and Dissertations

Automated Facial Expression Recognition (FER) has been a topic of study in the field of computer vision and machine learning for decades. In spite of efforts made to improve the accuracy of FER systems, existing methods still are not generalizable and accurate enough for use in real-world applications. Many of the traditional methods use hand-crafted (a.k.a. engineered) features for representation of facial images. However, these methods often require rigorous hyper-parameter tuning to achieve favorable results.

Recently, Deep Neural Networks (DNNs) have shown to outperform traditional methods in visual object recognition. DNNs require huge data as well as powerful computing units …

Is The Reliability Of Objective Originality Scores Confounded By Elaboration?, Shannon Marie Maio

Electronic Theses and Dissertations

The increased use of text-mining models as a scoring mechanism for divergent thinking (DT) tasks has sparked concerns about the ways in which automated Originality scores may be influenced by other dimensions of DT, especially Elaboration. The debate centers around the question of whether too much variance in automated Originality scores is accounted for by the number of words a participant uses in a response (i.e., Elaboration), and, thus, how the influence of Elaboration can affect the reliability of Originality scores. Here, a partial correlation analysis, in conjunction with text-mining and psychometric modeling, is conducted to test the degree to …

Climate Change And Seed Security Among Smallholder Farmers In Northern Ghana, Michael Biwalib Madin

Electronic Theses and Dissertations

Smallholder agriculture is highly susceptible to climate variability and change. According to recent projections by the Intergovernmental Panel on Climate Change, this sensitivity would likely increase in the coming decades, with more erratic rainfall, prolonged dry periods, shorter growing seasons, and seed germination failures. In the African context, the mechanisms through which these ecological stressors would affect seed security are poorly understood. Drawing upon a case study of semi-arid Ghana, this study examines climate change impacts on seed security among smallholder farmers. It adopts a mixed-methods approach with intensive fieldwork in two farming communities. Conceptually, the study uses a political …

Solvolytic Lignocellulosic Biomass Liquefaction, Mustafa Alluhaibi

Electronic Theses and Dissertations

Increasing energy demand, petroleum prices, global warming, and depleting fossil fuel resources are the main challenges faced by the human beings. Many scientists are searching for sustainable and alternative sources of fossil fuels as solutions to these challenges. Lignocellulosic biomass is one of the renewable and eco-friendly abundant sources that has been considered by both academia and industry sectors as a renewable source for bio-oil and chemicals. Direct liquefaction of biomass in the sub-/super-critical solvent has considered a practical method to convert lignocellulosic material into liquid fuel. However, undesirable properties such as poor stability, low energy value, and high acidity …

Particle Injection Simulation On Cold Spray Technology, Christopher A. Santini

Electronic Theses and Dissertations

Computational Fluid Dynamics (CFD) is a useful tool when it comes to research in the fields of Aerodynamics, Turbomachinery, and is used in several other fields of research. CFD is an important tool in the engineering industry because it allows for understanding and evaluation of a new design, this can lead to advancements in developing a more efficient and effective design. This tool helps in the understanding of the flow phenomena and how it can interact with its surroundings. One of the main reasons in the use of CFD is to reduce the cost of testing a design by running …

Higher Temperatures Have Contrasting Effects On Different Components Of Forage Quality For Caribou In Northern Alaska, Heidi Becker

Electronic Theses and Dissertations

Rising temperatures in the Arctic may affect vegetation, which in turn can affect herbivores, such as caribou, that rely on these plants for forage. Several plant traits contribute to forage quality, including digestibility, nitrogen content, and antiherbivory secondary compounds, but the effect of temperature on these traits individually and combined is unclear. I conducted a three-component study on the effect of higher temperatures on the forage quality of graminoids, deciduous shrubs, and evergreen dwarf shrubs on the North Slope of Alaska. The components included: 1) short and long-term experimental warming, 2) natural temperature variation between south and north-facing slopes, and …

Screening Of Catalysts For The Subcritical Water Depolymerization Of Lignin, Balawanthrao Jadhav

Electronic Theses and Dissertations

The current world population is completely rely on the non-renewable resources such as coal, fossils, and natural gas to get the energy, fuel and value-added chemicals. The increasing the demand of utilizing non renewable resources leads to severe problems such as global warming, climate changes, and environmental pollution. The renewable resources such as wind, solar energy, and biomass is an alternative sources to overcome these problems and to save the environment. Biomass made up with the cellulose, hemicellulose, and Lignin. Lignin is a copolymer of phenolic monomers and inexpensive naturally occurring complex material to produce the value-added chemicals and various …

Characterization Of Naturally Derived Polymer By Oxidative, Thermal, And Spectrometric Methods, Ranen Roy

Electronic Theses and Dissertations

Extensive use of fossil fuel for different purposes has resulted in significant depletion of it at an alarming rate. Therefore, a potential and sustainable alternative source are badly needed at this moment. Nowadays, lignocellulose biomass is appealing to much interest by the researchers because of its potential nature as a renewable carbon source. It is the most abundant renewable source which is composed of cellulose, hemicellulose, and lignin. Among them, lignin is considered the 2nd most abundantly natural polymer after cellulose which comprises 10-30 % of biomass depending on the source and the environment. Lignin is a three-dimensional cross-linked organic …

Development And Validation Of Advanced Analytical Methods For Pesticides, Per- And Polyfluoroalkyl Substances, And Opioids In Soil And Drinking Water, Christopher Skaggs

Electronic Theses and Dissertations

Environmental pollution from contaminants is a serious concern in a world where more and more pesticides and pharmaceuticals are being used, sometimes improperly and in excess. Since pesticides are used on practically every crop on Earth, it’s no surprise that these compounds are detected in soil, water, and processed agricultural commodities meant for human consumption. Additionally, because of the ubiquity of pharmaceuticals, specifically opioids, and their inherent addictive properties, these compounds are being over-consumed. Because current waste-water treatments can be insufficient to remove them from water sources, this consumption has led to the detection of these compounds in drinking water. …

Understanding South Dakota Farmers’ Intentions To And Adoption Of Conservation Practices: An Examination Of The Theory Of Planned Behavior, Edem Avemegah

Electronic Theses and Dissertations

Conservation agriculture practice is a sustainable farming method based on three principle: crop diversification, minimal soil disturbance or movement and permanent or semi-permanent of soil cover. Government and stakeholders within the agricultural sector in the United States are promoting conservation farming practices but limited voluntary adoption still exists among producers at the farm level. This research study investigated the factors that influence the adoption of conservation practices among producers in the eastern and central parts of South Dakota (SD). A modified theory of planned behavior (TPB) is used as a framework alongside socioeconomic and demographic indicators to understand farmers’ current …

Crop Rotations, Tillage And Cover Crops Influences On Soil Health, Greenhouse Gas Emissions And Farm Profitability, Jasdeep Singh

Electronic Theses and Dissertations

This study assessed the effects of three levels of crop rotation: [2-yr; corn (Zea mays L.)- soybean (Glycine max L.), 3-yr; corn-soybean-oat (Avena sativa L.) or 4-yr; cornsoybean- oat-winter wheat (Triticum aestivum L.)], two tillage [conventional-till (CT) and no-till (NT)], and two winter cover cropping systems [cover crop (CC) or fallow control (NC)] on soil biochemical and physical properties, greenhouse gas emissions (GHG), microbial community composition, crop yield and farm profitability under silty clay loam soil of south eastern South Dakota. Experimental design was a randomized complete block design in a split-split plot treatment arrangement with four replications. Rotations, tillage …

Examining Biodiversity Metrics And The Utility Of Dna Barcoding In The Northern Great Plains, Sarah Herzog

Electronic Theses and Dissertations

Due to heavy threats to remaining global floral and faunal diversity, it is imperative we can identify species and quantify ecosystem health to find best practices for land management and conservation. The tallgrass prairies of the Northern Great Plains are one example of a heavily imperiled ecosystem. The tallgrass prairies have been reduced to less one percent of their historical extent and are facing continued loss. Genetic approaches and evolutionary theory offer insights for identifying species and assessing how biodiversity metrics may correlate with ecosystem processes. My two projects aim to address two facets imperative to conservation in the tallgrass …

The Impact Of Subsurface Physical Characteristics On The Effectiveness Of Subsurface Drainage In The Northern Great Plains, Mehmet Emin Budak

Electronic Theses and Dissertations

World-wide, salinity and sodicity problems are increasing in coastal, irrigated and dryland agricultural systems. Traditional reclamation techniques for saline sodic soils include improving soil drainage by installing subsurface drainage, leaching with high quality water, and applying a source of calcium. However, due to differences in the soil parent material these traditional approach treatments were ineffective in removing sodium and other salts out of the soil profile of South Dakota. Understanding how the surface and subsurface soil characteristics and management interact to affect the sustainability of these systems is the first step in remediation. Each region and soil have a slightly …

Urban Informality, Environmental Xenophobia, And Infrastructures Of Citizenship: The Political Lives Of Nicaraguan Migrants In The Informal Settlement Of La Carpio, Costa Rica, Nikolai Alexander Alvarado

Electronic Theses and Dissertations

This dissertation examines urban politics, environmental justice, and infrastructure from the vantage point of South-South migration. It focuses on the work of Nicaraguan migrants living in the informal settlement of La Carpio in San José, Costa Rica, as they negotiate rights in the form of urban services. Nicaraguans in La Carpio have organized politically since 1993 to self-install, demand, and negotiate services such as potable water and electricity. In the process, they successfully compel local authorities to allocate these services and grant them an implicit recognition of their right to remain and live a decent life, regardless of their status. …

A Study Of Chloride Levels In Pine Creek, Allegheny County, Pa, Selina Prettner

Electronic Theses and Dissertations

Pine Creek is a 22.8-mile long tributary to the Allegheny River draining over 67 square miles of northern Allegheny County, PA. The main stem runs along Route 8 and receives extensive runoff from road salt from deicing. A site near Etna, PA sampled biweekly in 2013 consistently showed elevated conductivity that correlated with increased chloride levels. Winter road deicing runoff produced acute chloride concentrations up to 678 mg/L. Chloride fluctuated in the summer and autumn months but did not exceed the USEPA Secondary Drinking Water Standard (250 mg/L) or the aquatic life criterion for chronic concentrations (230 mg/L). Sampling throughout …

Greening Of Catalytic Processes Using First-Row Transition Metals For Atom Transfer Radical Addition And Transfer Hydrogenation, Gabrielle Pros

Electronic Theses and Dissertations

This work focused on “greening” catalytic processes, atom transfer radical addition (ATRA), which adds an alkyl halide across and alkene, and transfer hydrogenation/dehydrogenation, which reduces a carbonyl without needing direct H₂ gas. Part of “greening” of these processes is through using abundant first row metals, Cu and Ni for catalysis. One aim was to design new ligands which would be more active in these systems; the second was investigation of additives for catalyst regeneration to reduce the catalyst loading necessary for high yields.

The TPMA^* family was investigated in ATRA. Rate constants followed the expected trend, which increased …

C-Metalated Nitriles: Diastereoselective Alkylations And Arylations, Robert John Mycka

Electronic Theses and Dissertations

Development of an sp³ hybridized halogen-magnesium exchange route to Grignard reagents, chelation-controlled asymmetric induction of γ- and δ-hydroxynitriles as well as a diastereoselective arylation procedure for C-zincated nitriles have been explored. Sequential addition of i-PrMgCl and n-BuLi to 3- and 4-carbon iodoalcohols triggers a facile halogen-metal exchange to generate cyclic magnesium alkoxides capable of intercepting electrophiles to produce a diverse range of substituted alcohols. This work advances progress toward the synthesis of highly desirable chiral Grignard reagents.

Double deprotonation of γ- and δ-acyclic hydroxynitriles with i-PrMgCl effects highly diastereoselective alkylations via a singly-chelated magnesiated nitriles. …