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Experimental, Analytical, And Numerical Evaluation Of The Mechanical Properties Of The Brain Tissue, Aref Samadidooki

LSU Doctoral Dissertations

A true understanding of the mechanisms behind most of the brain diseases is still out of reach. For several years, the interest of scientists has been focused on the genetic and biological causes, however, recent studies unraveled the importance of the biomechanics of the brain growth, folding, impact resistance, and deformation on its pathological conditions. While, a wide range of different methods have been used for characterization of the mechanical properties of the brain at the tissue level, the obtained results from different studies are extremely scattered and sometimes in contrast to one another. Since the brain tissue is extremely …

Development Of A Slab-Based Monte Carlo Proton Dose Algorithm With A Robust Material-Dependent Nuclear Halo Model, John Wesley Chapman Jr

LSU Doctoral Dissertations

Pencil beam algorithms (PBAs) are often utilized for dose calculation in proton therapy treatment planning because they are fast and accurate under most conditions. However, as discussed in Chapman et al (2017), the accuracy of a PBA can be limited under certain conditions because of two major assumptions: (1) the central-axis semi-infinite slab approximation; and, (2) the lack of material dependence in the nuclear halo model. To address these limitations, we transported individual protons using a class II condensed history Monte Carlo and added a novel energy loss method that scaled the nuclear halo equation in water to arbitrary geometry. …

Visualization And Quantification Of Cancer-Associated Enzymes With Fluorescent Small-Molecule Substrate Probes, Zhenhua Shen

LSU Doctoral Dissertations

Fluorescence imaging can be used both as a tool to diagnose diseases and guide treatment in clinical settings, and as a technique to monitor dynamic events or biological species in basic research. Therefore, there is a great need for the development of a multitude of fluorescent probes that can be incorporated with fluorescence imaging techniques to track and report endogenous enzymes with high specificity and selectivity. In contrast to always-on and targeted always-on fluorescent probes that continually emit light, activity-based substrate probes either emit low numbers of photons or are completely quenched. They can be converted to highly fluorescent reporters …

Templates For Representable Matroids, Kevin Manuel Grace

LSU Doctoral Dissertations

The matroid structure theory of Geelen, Gerards, and Whittle has led to a hypothesis that a highly connected member of a minor-closed class of matroids representable over a finite field is a mild modification (known as a perturbation) of a frame matroid, the dual of a frame matroid, or a matroid representable over a proper subfield. They introduced the notion of a template to describe these perturbations in more detail. In this dissertation, we determine these templates for various classes and use them to prove results about representability, extremal functions, and excluded minors.

Chapter 1 gives a brief introduction …

Investigation Of Structure And Dynamics Of Deep Eutectic Solvent Using Infrared Spectroscopy, Yaowen Cui

LSU Doctoral Dissertations

Deep Eutectic Solvents (DES) are liquid mixtures prepared from solids. As a new class of green solvents, DES not only share many properties with ionic liquids, such as low volatility, conductivity, tailorable constituents, but also have some advantages over ionic liquids, like easier preparation, safe and inexpensive materials, biodegradability, low toxicity, and excellent solubility. Because of those attractive properties, DES has been studied in many scientific and engineering fields. However, compared with the great number of studies of the application, many questions about structure and dynamics of DES are unanswered. To shed light on the mystery of solvent or solvation …

Two Results In Drawing Graphs On Surfaces, Joshua E. Fallon

LSU Doctoral Dissertations

In this work we present results on crossing-critical graphs drawn on non-planar surfaces and results on edge-hamiltonicity of graphs on the Klein bottle. We first give an infinite family of graphs that are 2-crossing-critical on the projective plane. Using this result, we construct 2-crossing-critical graphs for each non-orientable surface. Next, we use 2-amalgamations to construct 2-crossing-critical graphs for each orientable surface other than the sphere. Finally, we contribute to the pursuit of characterizing 4-connected graphs that embed on the Klein bottle and fail to be edge-hamiltonian. We show that known 4-connected counterexamples to edge-hamiltonicity on the Klein bottle are hamiltonian …

Essays On The Impact Of Parents' Investment And School Curriculum On Educational Outcomes In China, Han Yu

LSU Doctoral Dissertations

This dissertation consists of two essays studying how students’ educational outcomes are affected by parents’ investment and school curriculum, which are two of the most important determinants of students’ educational performance, respectively. Specifically, in chapter 2, I investigate whether Chinese children born in the auspicious years of Dragon perform better than their comparable peers in school. Using three recently collected datasets from China, I find that students born in the years of the Dragon indeed outperformed their peers in study. I furtherly test the possible mechanisms for the better performance of the “Dragons” in school. The results suggest that parents’ …

Children With Adha Or Anxiety Disorders: Are Common Or Specific Variables Associated With Decreased Performance On Intelligence Indices?, Franziska Noacklesage

LSU Doctoral Dissertations

Although overall psychopathology has been linked to lower intellectual functioning, research has yet to investigate whether one or multiple specific underlying symptom clusters significantly correlate with working memory (WM) and processing speed (PS) deficits. The current study investigated these relationships as they apply to Attention-Deficit/Hyperactivity Disorder (ADHD) and anxiety disorders. As such, one goal of this study was to investigate the extent to which common and specific symptom clusters would predict ADHD and anxiety diagnoses compared to a control group when PS and WM were partialled out. A further goal was to determine if one could differentially predict ADHD from …

A Comparison Of Causal Inference Methods And Their Application In Big Data Analytics, Xuan Wang

LSU Doctoral Dissertations

With the rise of Big Data analytics, the new field of causal inference (Pearl, 2009) has received more attention in business research fields such as Accounting (Lawrence, Minutti-Meza, & Zhang, 2011) and Marketing (Manganaris, Bhasin, Reid, & Hermiz Keith, 2010). Traditional statistics focuses on correlation which may lead to misleading conclusions because the estimates can be severely biased even when data sets are large. The objective of causal inference is to obtain estimates from observational data that are unbiased and can thus be interpreted as causal. This study provides a systematic comparison of the performance of four causal inference methods …

Shifting Niche Space In Coastal Landscapes: Spatio-Temporal Patterns Driving Submerged Aquatic Vegetation Across The Northern Gulf Of Mexico, Kristin Elise Demarco

LSU Doctoral Dissertations

Identifying distributions of submerged aquatic vegetation (SAV) across the northern Gulf of Mexico (NGOM) coastal landscape necessitates describing ecological processes in estuarine gradients. SAV assemblages are ecological indicators of aquatic ecosystem health; spatial and temporal distributions are strongly correlated to environmental conditions. Many wildlife species, including waterfowl, are dependent on SAV and seeds in NGOM coastal marshes for food and habitat. To understand SAV distributions at multiple spatial and temporal scales a multi-tiered project was designed to collect SAV presence, species assemblage, and cover data, and cores to describe seed food. The first tier sampled inter-annually in the growing seasons …

Generating Audio Using Recurrent Neural Networks, Andrew Pfalz

LSU Doctoral Dissertations

Long Short Term Memory cells are a type of recurrent neural network that perform well when predicting sequence data. This works presents four approaches to modeling audio data. The models are trained to predict either raw audio samples or magnitude spectrum windows based on prior input audio. In a process called sampling, the models can then be employed to generate new audio using what they learned about the data they were trained on.

Four methods for sampling are presented. The first has the model predict a vector for each vector in the input. The second has the model predict one …

Risk, Responsibility, And Ethics In Professional And Technical Communication, Charley Grant Silvio

LSU Doctoral Dissertations

In this project, I present a novel and alternative approach for considering ethics in professional and technical communication, namely the ethics of responsibility theorized primarily by phenomenologist Emmanuel Levinas. To apply this new approach, I investigate a contemporary example in the rhetoric of investment bank Goldman Sachs before and during the 2008 U.S. Financial Crisis. In the early chapters, I review conventional ethical approaches—traditional and postmodern—in technical and professional communication (TPC) and consider their application to the Goldman Sachs example. This analysis reveals that these approaches, while useful in understanding the report’s general ethical framework, don’t fully describe the ethical …

The Interval Dissonance Rate In Chopin’S Études Op. 10, Nos. 1-4: Dissecting Arpeggiation, Chromaticism, And Linear Progressions, Nikita Mamedov

LSU Doctoral Dissertations

Chopin’s twenty-seven piano études display the composer’s poetic musical language, uniting keyboard techniques, virtuosity, and artistic imagery, while preserving Romantic lyricism and songfulness. Each of these studies is unique in its set of pianistic challenges, compositional processes, and difficulty level. Schenkerian analysis provides an interpretation of relationships between the notes that constitute the harmony and the melody. This type of analysis allows one to understand the theoretical aspects that are necessary to play Chopin’s études. The Schenkerian theories can be used to amalgamate pianism and performance with harmony and analysis. Furthermore, the Schenkerian understanding of these études provides an analytical …

Mixed Categories Of Sheaves On Toric Varieties, Sean Michael Taylor

LSU Doctoral Dissertations

In [BGS96], Beilinson, Ginzburg, and Soergel introduced the notion of mixed categories. This idea often underlies many interesting "Koszul dualities." In this paper, we produce a mixed derived category of constructible complexes (in the sense of [BGS96]) for any toric variety associated to a fan. Furthermore, we show that it comes equipped with a t-structure whose heart is a mixed version of the category of perverse sheaves. In chapters 2 and 3, we provide the necessary background. Chapter 2 concerns the categorical preliminaries, while chapter 3 gives the background geometry. This concerns both some basics of toric varieties as well …

A Preliminary Examination Of The Time And Organization Preparation System-College (Tops-C) With Undergraduate Students, Ashley Elizabeth Bordelon

LSU Doctoral Dissertations

Many factors contribute to the educational success of undergraduate students, including personal beliefs, effort, and the ability to self-manage. Many students are not prepared for the rigors of post-secondary education. This need is particularly striking given the limited availability of manualized evidenced based interventions available to support college students with academic task demand management. This study sought to determine the efficacy of the Time and Organization Preparation System-College (TOPS-C), a program aimed to increase study skills, organization, self-regulated learning, and time management through direct instruction, group contingency, and performance feedback. To determine changes in skill level, students completed the Learning …

Hypothesis Testing And Model Estimation With Dependent Observations In Heterogeneous Sensor Networks, Sima Sobhiyeh

LSU Doctoral Dissertations

Advances in microelectronics, communication and signal processing have enabled the development of inexpensive sensors that can be networked to collect vital information from their environment to be used in decision-making and inference. The sensors transmit their data to a central processor which integrates the information from the sensors using a so-called fusion algorithm. Many applications of sensor networks (SNs) involve hypothesis testing or the detection of a phenomenon. Many approaches to data fusion for hypothesis testing assume that, given each hypothesis, the sensors' measurements are conditionally independent. However, since the sensors are densely deployed in practice, their field of views …

Endorectal Digital Prostate Tomosynthesis, Joseph Robert Steiner

LSU Doctoral Dissertations

Several areas of prostate cancer (PCa) management, such as imaging permanent brachytherapy implants or small, aggressive lesions, benefit from high image resolution. Current PCa imaging methods can have inadequate resolution for imaging these areas. Endorectal digital prostate tomosynthesis (endoDPT), an imaging method that combines an external x-ray source and an endorectal x-ray sensor, can produce three-dimensional images of the prostate region that have high image resolution compared to typical methods. This high resolution may improve PCa management and increase positive outcomes in affected men.

This dissertation presents the initial development of endoDPT, including system design, image quality assessment, and examples …

Investigating Trace Metal Sequestration Of Reducing Environments In Modern And Ancient Settings, Adam Charles Turner

LSU Doctoral Dissertations

The incorporation of trace metals into a variety of reducing sediments are important proxies for the oxic state of the water mass in which the sediments form. While much work has been done interpreting these proxies, questions remain on the exact processes and products in which trace metal proxies form. This work employs bulk geochemical techniques to investigate circulation in the Late Pennsylvanian North American Midcontinent Sea (NAMS), and then uses sequential extractions to further understand the chemical phases in which trace metals are incorporated. Sequential extractions are then used to further investigate how trace metals are sequestered in modern …

What Motivates Children To Respond? Functional Analysis And Intervention Of Math Computation Fluency, Catherine Rose Lark

LSU Doctoral Dissertations

An abundance of research exists supporting the use of functional analyses to assess and treat problem behavior. In contrast, little research has been conducted on the application of functional analysis (FA) procedures to academic behaviors. The current study attempted to fill this research gap by conducting an FA of academic responding for five elementary students with low math fluency. Sessions were conducted using both a traditional reinforcement schedule of a fixed ratio of one (FR-1) as well as a more practical reinforcement schedule of a fixed ratio of ten (FR-10) to examine the effects of the reinforcement schedule on the …

Entropic Bounds On Two-Way Assisted Secret-Key Agreement Capacities Of Quantum Channels, Noah Anthony Davis

LSU Doctoral Dissertations

In order to efficiently put quantum technologies into action, we must know the characteristics of the underlying quantum systems and effects. An interesting example is the use of the secret-key-agreement capacity of a quantum channel as a guide and measure for the implementation of quantum key distribution (QKD) and distributed quantum computation. We define the communication task of establishing a secret key over a quantum channel subject to an energy constraint on the input state and while allowing for unlimited local operations and classical communication (LOCC) between a sender and receiver. We then use the energy-constrained squashed entanglement to bound …

Nutrition Misconceptions And Awareness Among College Students In A University Community, Shervia Singleton Taylor

LSU Doctoral Dissertations

Identification of misconceptions of macronutrients (carbohydrate, protein, and fat ) and awareness of ailments linked to micronutrients (potassium, fiber, Vitamin D. and food label use) based on certain demographics are vital to improving and developing long term health benefits, increasing consumption of fruits and vegetables, and decreasing healthcare cost associated with poor dietary lifestyles among non-major general biology college students at a historically black college and university located in the southern part of the United States. Misconception Identification (all groups) was determined using the pretest and posttest Nutrition Knowledge Test via Qualtrics that included two and three tiered question format …

On Structures Of Large Rooted Graphs, Shilin Wang

LSU Doctoral Dissertations

A rooted graph is a pair (G,R), where G is a graph and R⊆V(G). There are two research topics in this thesis. One is about unavoidable substructures in sufficiently large rooted graphs. The other is about characterizations of rooted graphs excluding specific large graphs.

The first topic of this thesis is motivated by Ramsey Theorem, which states that K_n and ¯(K_n ) are unavoidable induced subgraphs in every sufficiently large graph. It is also motivated by a classical result of Oporowski, Oxley, and Thomas, which determines unavoidable large 3-connected minors. We first determine unavoidable induced subgraphs, and unavoidable subgraphs in …

Development Of A Literary Dispositif: Convening Diasporan, Blues, And Cosmopolitan Lines Of Inquiry To Reveal The Cultural Dialogue Among Giuseppe Ungaretti, Langston Hughes, And Antonio D’Alfonso, Anna Ciamparella

LSU Doctoral Dissertations

This dissertation seeks to create a literary dialogue among the Italian poet Giuseppe Ungaretti, the African American author Langston Hughes, and the Quebecois writer Antonio D’Alfonso. Giuseppe Ungaretti and Langston Hughes were more or less contemporaries. Ungaretti was born in 1888 and Hughes in 1902, and both were active in modernist movements that shaped the literary history of their own countries. D’Alfonso was born in Canada about half a center after Ungaretti and Hughes. Besides significant generational differences, these three authors also underwent personal and intellectual experiences that shaped their writing in seemingly incomparable ways. While a traditional comparative approach …

Workflows For X-Ray And Neutron Interferometry/Tomography As Applied To Additive Manufacturing, Jumao Yuan

LSU Doctoral Dissertations

Grating-based interferometry/tomography is being rapidly developed for non-destructive evaluation of additive manufacturing test articles. An application requiring an efficient workflow is extremely necessary for stress and fatigue testing samples.

At present, scientific workflows play an important role for computational experiments in additive manufacturing 3D printing and interferometry/tomography imaging analysis. A clear workflow template allows scientists to process experiments easier and faster. Work flow library grows, but to find an appropriate workflow for their task is challenging. In our research, there are mainly three portions in the workflow, interferometry analysis, image reconstruction and 3D visualization. Currently, the hierarchy of workflows in …

The Effects Of Metal Speciation, Content And Cluster Size In Fly Ash On Pcdd/F Formation, Xia Guan

LSU Doctoral Dissertations

Transition metal oxides present in waste incineration systems have the ability to catalyze the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) through surface mediated condensation of organic dioxin precursors. Current studies have concentrated on the catalytic effects of individual transition metal oxides, while the complex composition of fly ash introduces the possibility of synergistic or antagonistic effects between multiple, catalytically active components. In addition, there is at present hardly a quantitative link between fly ash physical properties/chemical reactivity and PCDD/Fs yield.

We have tested fly ash surrogates containing different ratios of iron (III) oxide and copper (II) oxide …

Formation Control Of Multi-Agent Systems By Using Rigid Graphs, Pengpeng Zhang

LSU Doctoral Dissertations

This research is devoted to the decentralized formation control of multi-agent systems in two- and three-dimensional space. Rigid graph theory is used to describe the interactions between the agents, and Lyapunov theory and input-to-state stability are the main tools for designing and analyzing the stability of the proposed formation controllers. Two formation problems are addressed in this work: formation acquisition, where the goal is for the agents to form and maintain a pre-defined geometric shape; and formation maneuvering, where the agents need to acquire a formation and move cohesively as a virtual rigid body.

In the first problem, we tackle …

On The Computation Of The Rate-Equivocation Region For Wyner's Wire-Tap Channels, Meena Gangula

LSU Doctoral Dissertations

In a wire tap channel, the transmitter Alice communicates with the legitimate receiver, Bob, in the presence of another receiver, Eve. The goal is to keep the wiretapper, Eve, as ignorant as possible about the information sent to Bob. For communication channels where the adversary, Eve, eavesdrops on the information sent between the legitimate users by wiretapping at the Bob's end, Wyner introduced secure encoding schemes and showed that non zero reliable transmission rate is possible in perfect secrecy. Wyner also obtained the information theoretic achievable rate equivocation region (Rb, DeltaK) for discrete memoryless wire tap channels. The rate equivocation …

Linguistic Political Ecology With The Ngäbe Indigenous People Of Panama, Ginés A. Sánchez Arias

LSU Doctoral Dissertations

Indigenous communities from all corners of the globe live in uncertain times. From the vantage point of their “remote" lands, they undergo some of globalization’s most harmful externalities. Their homes become increasingly harder to maintain as extractive industries, development schemes, clandestine land grabs, and national bureaucracies encroach creating new colonial lands. First by assimilation, and then integration, these processes systematically undermine indigenous culture and autonomy. In place of such destructive coloniality, indigenous societies shelter unique ecological and linguistic knowledge that continues to serve their progress. This research applies lessons learned from studying with Ngäbe communities of western Panama, towards a …

Weary At Work: A Conservation Of Resources Approach To Understanding Job-Related Boredom, Candace Angela Esken

LSU Doctoral Dissertations

Despite the pervasive nature of boredom in the workplace, there has been surprisingly little theoretical and empirical analysis on the phenomenon. The existing research suffers from several shortcomings preventing progress on job-related boredom including the lack of an agreed definition and a properly developed and validated measure of the construct. This dissertation addresses these deficiencies by first developing and validating a psychometrically sound measure for job-related boredom. Then, drawing upon conservation of resources theory, hypotheses for the antecedents and consequences of job-related boredom were tested using a sample of 199 employees at a large insurance organization in the United States. …

A Turning Point In The Life Course: A Comparative Analysis Of Influences Of Military Service On Mental Health And Deviance, Ugur Orak

LSU Doctoral Dissertations

Military service is an important school of training and one of the largest employers in the U.S., functioning as a major turning point in the lives of millions of American individuals. Whether serving in the military has a beneficial or a detrimental impact on individuals’ tendencies to engage in deviant behaviors has long been discussed and empirical studies have presented inconsistent results. In addition, research examining the interplay between military service, deviance, and mental health has generally focused on the service in a combat zone or during wartime and centered upon certain types of deviance and mental health problems. Addressing …