Digital Commons Network^™

Metal Fatigue And Crack Propagation Using Thermodynamic/Thermoelectric Approach, Behnam Hajshirmohammadi

LSU Doctoral Dissertations

The present dissertation concentrates on the fatigue life of metals and fatigue crack growth (FCG). The basic concept of fatigue thermodynamics is used for this purpose. With the application of thermoelectricity, a method is developed on the basis of fracture fatigue entropy (FFE) for the rapid estimation of the fatigue life of components. To this end, thermoelectric signals captured from a specimen during cyclic loading are analyzed, and a procedure is proposed for the calculation of fatigue life based on the thermoelectric signals in the beginning and the steady-state zone of fatigue. Temperature gradient and electric potential gradients in metals …

Interface-Induced Lattice Structure And Magnetism In Ultrathin Transition Metal Oxide Trilayers, David Howe

LSU Doctoral Dissertations

The study of magnetism has been a rich playground in condensed matter physics due to the multiple mechanisms capable of producing the effect and its relationship to multiple characteristics of a material. Transition metal oxides (TMOs) have been of particular interest for ongoing research into magnetic phenomenon due to the abundance of interesting physical phenomena found in member systems such as colossal magnetoresistance, skyrmion formation, and interface-driven 2D electron gases. Thin films introduce an additional thickness-dependent element, where reduction below a critical thickness eliminates the magnetic coherence of a system and FM order is lost. The atomic structure of these …

Investigation Of Arabidopsis Extremophyte Relatives, Schrenkiella Parvula And Eutrema Salsugineum Reveals Different Roads Leading To Salt Stress Tolerance, Kieu-Nga Thi Tran

LSU Doctoral Dissertations

How plants adapt to salt stress has been a central question in plant biology for decades. Yet we have not been able to fully understand the molecular networks and genetic mechanisms underlying this complex trait. Most of the genetic work on salinity stress has focused on understanding salt stress responses in the leading, yet a salt-sensitive model Arabidopsis thaliana. With the recent availability of genomes for wild-relatives of A. thaliana, we can now investigate how naturally salt adapted plants may have evolved modified or novel molecular networks to adapt to salt stress. Therefore, my research utilizes a comparative …

De Finetti’S Theorem In Categorical Probability, Tobias Fritz, Tomáš Gonda, Paolo Perrone

Journal of Stochastic Analysis

No abstract provided.

Evaluation Of The Effectiveness Of Aeration During Washing To Dislodge Microorganisms From Cucumbers And Bell Peppers, Julysa Benitez

LSU Master's Theses

Microorganisms may attach firmly to produce matrices and could affect the efficacy of disinfectants. The purpose of this study is to evaluate the effectiveness of aeration to reduce microbial risk during washing and sanitizing of fresh produce. Bell peppers and cucumbers were spot inoculated with Listeria innocua, E. coli O157:H7, and Salmonella; after drying in the biosafety cabinet for 1h, these were washed with water or sanitized with 100 ppm of chlorine for 3 min with or without aeration. Bell pepper and cucumber samples were placed in sterile bags with PBS after treatment. Bell peppers were processed in the stomacher …

Incorporating Student Reading Interests Into The Curriculum, Tia Denise Walker

LSU Master's Theses

The purpose of this research was to examine the reading habits and interests of secondary school students in an urban community in order to discover ways to increase student reading interests. The researcher wanted to understand why adolescents choose to read or not to read certain texts and understand the reading behaviors of these students. The study focused on students’ intent to read certain texts such as traditional books and non-traditional texts. To gain knowledge on a larger population of students, a questionnaire based on student reading habits was distributed to all students enrolled in English 1 at the research …

Corn Nitrogen Management Under Different Tillage Systems, Akshara Athelly

LSU Master's Theses

Adoption of no-tillage (NT) and cover crops (CC) significantly effect soil physicochemical properties and nutrient cycling that necessitates modified nutrient management to maximize crop yields. Two field experiments were conducted to evaluate N-sources Urea Ammonium Nitrate (UAN), urea, and urea+ N-stabilizer (urea+ stab) and N-split applications 100%N at V2 (S1), 25%N at V2+75%N at V6 (S2), 25%N at V2+ 50%N at V6+ 25%N at VT (S3) in a sandy loam soil and three CC wheat (Triticum aestivum), hairy vetch (Vicia villosa) , and radish (Raphanus sativus) and their combinations along with three N-rates ( …

Income Inequality And Polarization In The United States, Tatum Colette Taylor

LSU Doctoral Dissertations

Economic inequality has been on the rise in the United States for decades, as has political polarization. Pulling from grievance theory and relative deprivation theory, I explore the relationship between these two trends, predicting economic inequality may actually contribute to citizen polarization. I also predict that polarization of identities, issue opinions, and feelings towards groups polarize differently. In this study I test using linear regression analysis and data primarily from the American National Election Study whether income inequality and perceived growth of the income gap over 20 years affect ideological, substantive, and affective polarization from 2004-2016. I also examine the …

Insights Into Abscisic Acid And Phosphatidic Acid Signal Transduction Dynamics In Arabidopsis Thaliana, Ruth Wanjiru Ndathe

LSU Doctoral Dissertations

Abscisic acid (ABA) is a plant hormone that triggers a signaling transduction in response to drought, salinity, and cold. The core components in the ABA signaling pathway that lead to downstream ABA responses have been identified.

Phosphatidic acid (PA) is a membrane phospholipid that is involved in the signaling pathway for ABA-induced stomatal closure. We tested whether PA is involved in the signaling pathway for ABA-induced gene expression as well, using model plant Arabidopsis thaliana. We selected the RD29A gene which is a canonical drought gene that is induced by ABA. We found that PA is not involved in …

Pore-Scale Modeling Of Fluid Flow And Particle Transport In Multi-Scale Porous Media, Bin Wang

LSU Doctoral Dissertations

Nanomaterials have recently gained much interest in the field of petroleum engineering and environmental engineering. Understanding the particle transport mechanisms in geological porous media is important to design fit-for-purpose nanomaterials and certain operating parameters for practical usage of those materials. It has been known that natural rock has multi-scale porosity (macroporosity and microporosity) in nature. The microporosity can have a strong impact on the flow and mass transport, but the microscale physics and macroscopic consequences remain poorly understood.

The first part of this dissertation introduces a new higher-order, locally mass conserving FEM method. Stokes equation and Darcy equation are solved …

African American English-Speaking Children's Judgments Of Grammaticality: Effects Of Clinical Status And Grammatical Structures, Lori Elizabeth Vaughn

LSU Doctoral Dissertations

African American English (AAE)-speaking children’s ability to judge the grammaticality of sentences was evaluated by their clinical status and grammatical structure. The study originated from a need to understand more about the tense and agreement systems of AAE speakers with specific language impairment (SLI) relative to their typically developing (TD) AAE-speaking peers. Tense and agreement forms are typically excluded from the assessment and treatment of children who speak AAE in fear of misinterpreting a dialect difference as a language disorder. As a result, limited information exists about the tense and agreement systems of AAE-speaking children.

The data were archival and …

Genetic Structuring And Community Assembly In Neotropical Birds, Oscar Johnson

LSU Doctoral Dissertations

The factors that influence how species form is of fundamental interest to biology. Under the framework of the speciation cycle, the process begins by population subdivision creating structured populations that then diverge until two new species form. Following speciation, however, continued divergence is necessary for these new species to be able to coexist without adverse interactions, known as the transition to secondary sympatry. At this point the speciation cycle is complete and the process can begin anew. Many of the factors influencing these processes remain poorly understood. Here, I explore the factors that influence speciation and community assembly in Neotropical …

Using Uav Technology Paired With Multispectral Cameras To Assess Crown Rust Epidemics In Oats, Turner A. Graham

LSU Master's Theses

Crown rust, caused by Puccinia cornonata f. sp. avenae, is a common disease of oats (Avena sativa) found virtually everywhere oats are cultivated. This disease has caused yield losses of 10 to 40% worldwide. Early detection is important for effective management. A more recently utilized technology in agriculture is unmanned aerial vehicles (UAVs). UAVs, or drones, equipped with cameras are now being used as a resource to take images of fields to identify pests and other issues that may be occurring. Normalized differentiated vegetative index (NDVI) is a numerical indicator used to determine the vegetative health of …

What The Shell? The Zooarchaeology Of Cerro San Isidro, Peru, Monica Fenton

LSU Master's Theses

Zooarchaeologists have documented the importance of marine resources in the ancient Andes, and the first field season at Cerro San Isidro (Ancash, Peru) proves no different. The multi- component hilltop archaeological complex lies in the agriculturally rich Moro Pocket of the middle Nepeña Valley, at least an eight-hour walk from the ocean on the north-central coast. Between June and August 2019, members of the Proyecto de Investigación Arqueológica Cerro San Isidro carried out the first scientific excavations at this important ancient human settlement. Block excavations focused on a hypothesized elite compound, documenting intermittent occupations from the Late Formative (c. 600 …

Efficiency Of Teaching Sight Words In Similar Vs Dissimilar Sets, Jensen Chotto

LSU Master's Theses

Early reading intervention can decrease the likelihood that children who struggle with reading develop long-term reading problems. Due to the prevalence of words that cannot be read phonetically in the English language, sight word instruction is required to supplement phonics instruction. In this study, we compared the effects of creating sets of sight words with the same starting letter (3 words per set, 3 total sets) versus distributing words with the same starting letter across sets when assessing acquisition of the combined set (9 words) in five 4-to-6-year-old children using a combined adapted alternating treatments design and pre-posttest design. All …

Evaluating Substrate Stratification Practices For Enhanced Water Resource Management In Nursery Production, Kristopher S. Criscione

LSU Master's Theses

The nursery and greenhouse industries have continued to increase in production and sales over the past two decades. This increase in horticultural production necessitates a greater demand for finite natural resources, specifically water. Sustainable water resource management will be critical to the success and continual growth of the nursery industry. Strategic irrigation scheduling and innovative substrate management practices can improve nursery resource efficiency. Soilless substrates were originally utilized by the industry to increase substrate air-filled porosity, to ensure adequately drained container systems. Thus, the implementation of these soilless substrates can lead to an inefficient use of water and fertilizer. Substrate …

Temperature Affects The Time Required To Discern The Relationship Between Primary Production And Export Production In The Ocean, Edward Laws, Kanchan Maiti

Faculty Publications

No abstract provided.

Temperature Affects The Time Required To Discern The Relationship Between Primary Production And Export Production In The Ocean, Edward Laws, Kanchan Maiti

Faculty Publications

No abstract provided.

Casting A Critical Lens On Global Development: A Multimethod Investigation Of The Masculine Hegemonic Forces That Marginalize Women In Agriculture, Morgan Alyse Richardson Gilley

LSU Doctoral Dissertations

A critical link between gender equality and agricultural development has been established in the literature. However, disparities between genders have persisted in many areas of the developing world. One strategy that has been used to reduce gender inequalities has been educational outreach opportunities through agricultural extension, which has provided women a critical pathway to empowerment. Despite this, a lack of knowledge on the experiences of women in agriculture throughout Southeast Asia has served as a barrier to the advancement of such work. This investigation sought to better understand the issues facing this region’s fight to attain gender equality. To achieve …

Consumers' Perception Of Food Containing Insect Protein Affected By Serving Condition And Questionnaire Protocol, Yupeng Gao

LSU Master's Theses

Edible insects are a new sustainable protein source compared to meat. Western consumers show aversion to the prospect of insects as food due to unfamiliarity, food neophobia, and negative emotions. This dissertation research explored consumers’ emotional perception of insect-based food products presented under different testing conditions and examined the influence of other people’s emotional expressions towards consumers’ purchase decisions. To identify and rate emotion intensities, tests were conducted using three presenting formats including text, image, and an actual product; all of which were applied for both cookies containing insects and without insects. In addition to these presenting formats, news of …

Impact Of Software Changes On User Experience, Job Michael Champagne

LSU Doctoral Dissertations

Software changes are performed frequently to allow cutting edge features to be delivered to users in a timely manner and to assuage the ever increasing security vulnerabilities found in software. These changes, while necessary, can leave users dissatisfied with software that they use. Security patches can slow down computer performance, and extensive user interface changes can leave users dissatisfied. This research presents a methodology for identifying which software changes have high potential to cause user dissatisfaction. As a part of the methodology, we use natural language processing to analyze the software or system requirements business rule text to determine which …

The Confederate Stories Of America: The Short-Story Cycle And The Representation Of The American South, Ikuko Takeda

LSU Doctoral Dissertations

My dissertation examines the ways in which the short-story cycle has provided a unique generic framework for representing and investigating the complex interplay of contending forces that constitute what we think of as the American South. Often confused with a collection of disparate short stories or a novel, the short-story cycle is a collection of short stories in which each story is independent, but simultaneously interrelated to one another. Although the South has produced a number of short-story cycles or linked story collections, scholars have not paid much attention to the connection between the genre/form and the region. I consider, …

Fatigue Damage Quantification And Life Estimation With Provision For Microstructure, Arash Pourbagheri Jirandehi

LSU Doctoral Dissertations

This dissertation provides methodologies for the quantification of different forms of fatigue damage by considering the role of microstructure. The laws of thermodynamics in conjunction with Finite Element Method (FEM) are utilized to devise thermodynamically-base frameworks for the estimation of cyclic damage in polycrystalline metals. Accordingly, a microstructure-sensitive platform for fatigue life estimation is introduced. The proposed framework is assessed for 3D printed metallic alloys at room and elevated temperatures. Further, it is used to analyze the fatigue performance difference between additively manufactured Inconel 718 in three print orientations. This research is of fundamental vital interest because it ensures that …

High Precision Tissue Sampling For Mass Spectrometry, Chao Dong

LSU Doctoral Dissertations

A high precision infrared laser ablation sampling system was developed for localized tissue proteomics. A Schwarzschild reflective objective with 10 cm working distance and 0.3 numerical aperture was used to focus a mid-IR laser at 3 µm wavelength to a beam diameter of approximately 6 µm. A laser ablation spot size of 10 µm was achieved on thin ink films and tissue sections. The sampling system was used to ablate and capture rat brain tissue sections in transmission geometry. Captured tissue protein was extracted, digested, and analyzed with offline liquid chromatography tandem mass spectrometry (LC-MS/MS) for peptide and protein identification. …

Genome-Wide Analysis Of Peg3 Downstream Genes, Subash Ghimire

LSU Doctoral Dissertations

Paternally expressed gene 3 (Peg3) is an imprinted gene encoding a DNA-binding protein that is a predicted transcriptional repressor. The two studies presented here demonstrate the repressive functions of PEG3 in regulating different cellular processes and pathways, which were observed by analyzing the ChIP-seq results systematically using both bioinformatics tools and manual inspection of significant peaks. In the first part of the work, genome-wide features of ChIP-seq peaks were characterized and the potential de novo binding motif was reevaluated. Results suggested the transcriptional repressor role of PEG3 by binding to the conserved sequence motif of the target genes. …

The Influence Of Participation In Gambling Activities On The Personal Lives Of Gamblers As Perceived By Female Gamblers In Louisiana, Carondalette Turner

LSU Doctoral Dissertations

Historically, gambling has been a source of many ills within many cultures throughout the United States. During the last five years, there has been a precipitous surge in the accessibility of legalized gambling. Few studies have methodically surveyed the relationships between extent of gambling behavior and the consequences of gambling that may occur. The primary purpose of this study was to determine the influence of selected personal, and perceptual demographic characteristics on the extent of gambling behavior exhibited by female residents of Baton Rouge, Louisiana.

This study used a survey design with instrument distributed by hand at selected community organizations. …

Assessing Mangrove Wetland Structure And Function Regulated By Environmental Gradients Under Climate Change And Increasing Human Impacts: A Modeling Approach, Xiaochen Zhao

LSU Doctoral Dissertations

Mangroves are blue-carbon-rich wetlands that can potentially contribute to climate change mitigation policies. However, mangroves are increasingly impacted by both natural and human disturbances worldwide that require restoration and rehabilitation programs to advance their conservation. Yet, there are major knowledge gaps in our understanding of how local resources (nutrients), regulators (e.g., salinity) and hydroperiod gradients interact in controlling mangrove role as carbon sink or source at different spatiotemporal scales under increasing disturbance frequency and climate change.

Here, I developed a mass-balance-based hydrology model to estimate soil porewater salinity (PWS) in riverine mangroves along the Shark River estuary (SRE), South Florida; …

Investigation Of Sand-Biochar Mixtures As A Potential Roadway Fill Material, Katia J. Lele Lagmago

LSU Master's Theses

Biochar is a sustainable and lightweight carbon-rich material with a high surface area and porosity. Previous studies reported that biochar can reduce soil erosion and cracking, retain contaminants, and enhance soil aggregation. Given these favorable properties, soil-biochar mixtures have the possibility to serve as a multifunctional lightweight fill material for roadway embankment applications. The purpose of this research is to develop sand-biochar mixtures as a sustainable and multifunctional lightweight fill material for roadway embankment applications.

This research investigated the consolidation and hydraulic properties of sand-biochar mixtures by (1) performing 1D consolidation tests, (2) performing permeability tests, and (3) assessing the …

A Systematic Review And Reflection On The Dimensions Of Diversity Represented In Behavior Analytic Research, Jodie Waits

LSU Master's Theses

The United States continues to transition towards a majority-minority composition and this trend has most rapidly emerged for school-aged children. Work with diverse populations calls for specialized skills and training experiences, but these are not strongly reflected in most training programs in Applied Behavior Analysis (ABA). The present review was conducted to evaluate the scope and range of the dimensions of diversity included in Behavior Analytic research (e.g. race/ethnicity, gender, sexuality, etc.), as well as to compile recommendations related to culturally responsive practice in ABA. The search revealed a total of 50 publications featuring a dimension of diversity. These works …

Ontogeny And Resource Use Of Invasive Lionfish, Pterois Volitans, In Shallow Water Habitats Surrounding Summerland Key, Emily Shallow

LSU Master's Theses

The invasive red lionfish, Pterois volitans, has been shown to considerably reduce reef biomass via predation and competition in non-native ranges. Primary maintenance of lionfish is through human removal (e.g., culling), which does not sufficiently control the population due to deep-water spawning, recolonization of recently culled reefs, and ontogenetic migrations to mesophotic waters. Here, I investigated the diets and primary energy pathways during ontogeny in lionfish from the Florida Keys using stomach contents and stable isotope (δ¹³C and δ¹⁵N) analysis to better understand their role in the trophic food web. Additionally, isotopic overlap between lionfish …