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Investigation Of Subsurface Stratigraphy And Groundwater Dynamics In The Mississippi River Delta, An Li

LSU Doctoral Dissertations

The Mississippi River Delta (MRD) is socioeconomically important to the state of Louisiana and the United States. Various types of land-water system data have been collected in the MRD. However, very few efforts have been made to utilize these datasets in modeling regional stratigraphy and groundwater dynamics in the MRD, especially for the upper 50 m of the depth. In this interval of depth, the Mississippi River and surrounding interdistributary bays intensively interact with the groundwater system. The lack of knowledge in regional stratigraphy and groundwater dynamics hinder an understanding of how hydrogeological setting affects processes such as surface-groundwater interaction, …

Ultrafast And Real-Time Dynamics Of Nanomaterials Studied By Advanced Spectroscopic Techniques, Jeewan Chaminda Ranasinghe

LSU Doctoral Dissertations

Ultrafast and nonlinear spectroscopies are used to study excited-state dynamics and monitor real-time growth dynamics of different types of nanomaterials. In the first study, the growth dynamics of colloidal gold-silver core-shell nanoparticles are studied using in situ second harmonic generation and extinction spectroscopy. The growth lifetimes are studied under different reaction conditions, resulting in different silver shell thicknesses, with spectral comparisons to finite-difference time-domain calculations. The results are consistent with a three-step growth process. During the first step of the nanoparticle growth reaction, rough and uneven surfaces are formed rapidly giving rise to plasmonic hot spots with corresponding broad, red-shifted …

A Numerical Investigation Of Sediment Dynamics In The Northern Gulf Of Mexico In Connection With Hurricanes, Fluid Mud, Climate Change, And Biogeochemical Cycling, Zhengchen Zang

LSU Doctoral Dissertations

Sediment transport and deposition in marginal seas is jointly controlled by many factors including hydrodynamics, fluvial inputs, and the characteristics of sediment particles. This dissertation study employs the coupled ocean-atmosphere-wave-and-sediment transport modeling system (COAWST) to investigate the mechanism of sediment transport in the northern Gulf of Mexico (nGoM) on different temporal scales, as well as its interaction with biogeochemical processes.

First of all, a three-way coupled (atmosphere-wave-ocean) hurricane model reproduced the hydro- and sediment dynamics during hurricane Gustav (2008). Intensive alongshore and offshore currents were simulated on the eastern/western sectors of hurricane track, respectively. High suspended sediment concentration (SSC) was …

Silica And Siloxane Model Systems, Bruno Jakobi

LSU Doctoral Dissertations

This dissertation focuses on the development and synthesis of model system for the investigation of the morphology, interactions, and dynamics in linear and branched polymers and polymer nanocomposites. The materials are designed to reduce the number of uncontrolled parameters and to be ideally suitable for neutron scattering studies. Hereby, two main objectives are defined:

The first project is to develop model nanocomposites based on the grafting of poly(dimethylsiloxane) (PDMS) to primary particles and well-defined aggregates. For that purpose, the functionalization of silica nanoparticles with a chlorosilane and the influence of moisture on the reaction was studied. Higher grafting densities than …

Turn-On Near-Infrared Fluorescent Sensors For Selective Monitoring Of Kinase Activity, Gerard Thomas Ducharme

LSU Doctoral Dissertations

Reliable and selective detection of specific biopolymers is critical in a broad range of biomedical and technological areas, including availability of simple and efficient point-of-care-compatible systems for the detection of prognostic, pharmacodynamic and predictive biomarkers. Monitoring epidermal growth factor receptor (EGFR) tyrosine kinase is of major significance due to its link to many epithelial cancers. This task is complicated by the high rate of mutation occurring in patients treated with kinase inhibitors. This dissertation describes a conceptually novel design and synthesis of turn-on near-infrared fluorescent sensors for selective and sensitive detection of EGFR. The fluorescent signal generation mechanism is based …

Coupled Landscape And Channel Dynamics Across The Ganges-Brahmaputra Tidal-Fluvial Continuum, Southwest Bangladesh, Edwin Jefferson Bomer Iv

LSU Doctoral Dissertations

The Ganges-Brahmaputra (G-B) Delta of Bangladesh and India is widely considered to be one of the most vulnerable coastal systems in the world, owing to locally-accelerated sea level rise and landscape modification by human activities. Recent research efforts have identified pronounced elevation differences between natural and embanked areas in the G-B tidal delta plain, suggesting that natural landscapes are keeping pace with sea-level rise while anthropogenic locations are actively subsiding. However, this observation represents a singular point in time, and longitudinal trends of surface elevation in these regions are presently unknown. For communities residing in upstream regions of G-B delta …

Supercritical Co2 Foam Enhanced Oil Recovery: From Mechanistic Model Fit To Lab Experiments To Field-Scale Evaluation, Mohammad Izadi

LSU Doctoral Dissertations

This study investigates how a mechanistic foam modeling approach based on bubble population balance is applied to a series of laboratory experimental data of a supercritical CO₂ foam in reservoir conditions to extract model parameters (topic 1). The model with model parameters determined from the fit is then used to estimate how far fine-textured strong foam can propagate into the reservoir, before turning into coarse-textured weak foam and before being segregated by gravity (topic 2). With the help of mechanistic model, a possible range of gas mobility for supercritical CO₂ foam is calculated and the resulting gas-phase mobility …

Sequence-Defined Ionic Peptoid Block Copolymers: Synthesis And Solution Self-Assembly, Garrett Leigh Sternhagen

LSU Doctoral Dissertations

This work covers efforts to develop a peptoid-based model system for systematically studying the role of ionic functional groups in determining the structure of ionic block copolymer (BCP) self-assemblies in water. A key challenge in the study of polyelectrolytes is the lack of synthetic control over the location of ionic monomers along a polymer chain. We developed a model system based on sequence-defined ionic peptoid BCPs having discrete chain length and precisely positioned ionic monomers along the chain to specifically address this issue. In Chapter 1, synthetic strategies to access well-defined polypeptoids and their application in BCP synthesis are reviewed. …

Effect Of Surfactant, Oil:Water Ratio And Temperature On The Rheology Of Emulsion-Suspension Complex Fluids: Implications For Oil-Based Drilling Fluids, Gilles Landry Numkam

LSU Doctoral Dissertations

Drilling fluids are non-Newtonian mixtures that play a critical role in the timely and successful completion of oil and gas wells. In the particular case of offshore operations, proper design of drilling fluids is of paramount importance in the constant quest to lower break-even prices. Most downhole problems are directly or in-directly related to the rheological and physical properties of drilling fluids, thereby calling for a better understanding of the underlying changes of these properties with respect to drilling fluid composition and external conditions.

The current stance in the design of drilling fluids involves the selection of components and their …

Sub-Tidal Hydrodynamics Of The Multi-Inlet Lake Pontchartrain Estuary Influenced By Mississippi River Diversion And Wind Associated With Atmospheric Fronts, Wei Huang

LSU Doctoral Dissertations

In-situ observations and a Finite Volume Community Ocean Model (FVCOM) are used to investigate the cold front induced sub-tidal hydrodynamics of Lake Pontchartrain, a semi-enclosed low-salinity estuary with multiple inlets connecting to the open ocean. Observations show that the sub-tidal hydrodynamic responses are highly correlated with the meteorological parameters during cold front events. Model results indicate that, under barotropic conditions, the remote wind effect has the greatest contribution to the overall water level variation, while the local wind stress during cold front events determines the slope for the water level inside the estuary. An examination of a quasi-steady state force …

Modeling Chemical Reactivity In Aqueous And Organic Systems: From Electronic Structure Methods To Force Field Development, Caitlin Gibson Bresnahan

LSU Doctoral Dissertations

Modeling reactivity in chemical systems has evolved dramatically in line with the capabilities of modern computing. Despite the advances in computational ability, the level in which one can model a system depends on a number of factors including the region of reactivity, size of the system, level of sophistication required in the molecular description, and so on. Electronic structure methods allow for a detailed description of the potential energy surface and inherently include all essential physics required for reactivity to occur, however these methods are limited by their computational expense. On the other hand, force fields allow for an atomistic …

Multiphase Cfd Modeling In Particle-Laden Flows, Zhizhong Ding

LSU Doctoral Dissertations

Multiphase modeling is prevalent and useful in solving problems involving multiphase interactions such as fluid and solid. Applications conclude but not limited to fluidized bed, hydraulic conveying, and many others. Modeling techniques with multiple scales can provide various states of details with diverse computational resources used. In this dissertation, two CFD multiphase models are used to disclose interaction details in the particulate system. Two-Fluid Model is used to solve pulsed fluidized bed problem and immersed boundary method based direct numerical method is used to solve particle’s behavior in shear flow. Getting a better understanding of these problems to help to …

The Importance Of Landscape Position Information And Elevation Uncertainty For Barrier Island Habitat Mapping And Modeling, Nicholas Matthew Enwright

LSU Doctoral Dissertations

Barrier islands provide important ecosystem services, including storm protection and erosion control to the mainland, habitat for fish and wildlife, and tourism. As a result, natural resource managers are concerned with monitoring changes to these islands and modeling future states of these environments. Landscape position, such as elevation and distance from shore, influences habitat coverage on barrier islands by regulating exposure to abiotic factors, including waves, tides, and salt spray. Geographers commonly use aerial topographic lidar data for extracting landscape position information. However, researchers rarely consider lidar elevation uncertainty when using automated processes for extracting elevation-dependent habitats from lidar data. …

Performance Study Of Link Slab Continuity In Prestressed Concrete Bridges, Marco Tulio Canales Jr

LSU Doctoral Dissertations

Link slabs in bridges can be a cost-effective solution to increase the service life of bridge structures. The partial continuity condition in link slab bridges, however can be challenging to quantify. In this work link slab performance is studied by means of a parametric study, a long-term Structural Health Monitoring (SHM) System, and a detailed finite-element model.

The parametric study was conducted using mathematical and a two-dimensional (2D) finite element model. The study considers bridge design factors such as number of spans, span length, span length ratio, girder separation, and temperature settings, in conjunction with the corresponding girder and support …

Equivalence Of Contact Gluing Maps In Sutured Floer Homology, Federico Salmoiraghi

LSU Doctoral Dissertations

The contact invariant from Heegaard Floer homology is a useful tool for studying

contact structures. This invariant is preserved under cut-and-paste operations

by contact gluing maps of Honda, Kazez, and Matic. However, these maps are

difficult to compute in practice, even in simple cases.

We show that the contact gluing map of Honda, Kazez, and Matic

has a natural description in terms of bordered sutured Floer homology. In

particular, we establish Zarev’s conjecture that his pairing on sutured Floer

homology is equivalent to the contact gluing map.

Mathematics Experiences Of Students Who Are Blind Or Visually Impaired, Michaela Patricia Stone

LSU Doctoral Dissertations

Historically, researchers studying mathematics education for students with visual impairment (SVI) have faced several challenges. Quantitative researchers are limited by small sample sizes and the need to adapt traditional research instruments for accessibility by SVI. Qualitative research, most often conducted by sighted researchers and relying on the perspectives of sighted educators, suffers from the absence of the voices of the SVI being studied. Overwhelmingly, research on the mathematics education of SVI is explicitly grounded in deficit models of disability, falsely conflating the physical condition of impairment with the social act of disablement. Only in the past decade have critical disability …

Electromagnetic Sum Rules And Response Functions From The Symmetry-Adapted No-Core Shell Model, Robert Byron Baker

LSU Doctoral Dissertations

Recent developments in ab initio nuclear structure have provided us with a variety of many-body methods capable of describing nuclei into the medium-mass region of the chart of nuclides. One of these, the symmetry-adapted no-core shell model (SA-NCSM), capitalizes on inherent symmetries of the nucleus and is uniquely suited to examine the underlying physics of dynamical quantities, such as the response function.

We examine the applicability of the SA-NCSM to calculations of these quantities and assess the quality of its inputs by calculating electromagnetic sum rules and response functions with the Lanczos sum rule method and Lanczos response function method, …

Simulations Of Strong-Field Ionization In Molecules Using Tuned Range-Separated Time-Dependent Density Functional Theory, Adonay Sissay

LSU Doctoral Dissertations

Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this dissertation, we develop a time dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating …

Evaluating The Impact Of Intrusive Advising On Undergraduate Student Retention, Rebecca E. Caire

LSU Doctoral Dissertations

In this study, I investigated the impact of intrusive advising upon undergraduate student retention. Specifically, I sought to identify the background characteristics of at-risk students at the midterm point in a semester, and whether significant differences existed among students who were retained in comparison with those students who were not retained. In addition, I examined the extent to which intrusive advising interventions predicted student retention when controlling for student demographics. Although the intrusive advising interventions were not statistically significant in this model, several notable findings emerged regarding groups of at-risk students who were more or less likely to be retained …

The Impact Of Formal Panhellenic Recruitment On The Development Of Efficacy For Sorority Women, Amanda Jill Horvat

LSU Doctoral Dissertations

Little to no research has been conducted to assess the impact of formal sorority recruitment processes on efficacy levels of sorority women. While numerous studies have been conducted concerning the development of individual women and skills gathered throughout their collegiate experience, there has been limited research on how participation in sorority recruitment may impact psychological and physiological states, and increase or decrease self and collective efficacy.

If the original intent of sororities was to provide friendship, support, and encouragement, are current formal recruitment methods, supported by the National Panhellenic Conference, meeting that goal? Addressing this question requires an in-depth understanding …

Exploring The Link Between Students’ Usage Of Aleks And Their Performance On State Benchmark Assessments In Mathematics, Verna Marie Richard

LSU Doctoral Dissertations

The purpose of this mixed methods study was to investigate relationships between students’ ALEKS usage, teachers’ implementation of ALEKS, and student performance on the 2017 – 2018 LEAP 2025 mathematics assessment. The quantitative portion of the study involved district-level analyses and teacher-level analyses that explored relationships between students’ ALEKS usage and LEAP performance. The qualitative portion of the study took into consideration previous research findings that have reported associations between program implementation and student achievement. This portion of the study included thematic analyses that examined the following relationships: ALEKS implementation in relation to teacher groups (i.e., RtI 8, Math 8, …

Quantum Cluster Algebras At Roots Of Unity, Poisson-Lie Groups, And Discriminants, Kurt Malcolm Trampel Iii

LSU Doctoral Dissertations

This dissertation studies quantum algebras at roots of unity in regards to cluster structure and Poisson structure. Moreover, quantum cluster algebras at roots of unity are rigorously defined. The discriminants of these algebras are described, in terms of frozen cluster variables for quantum cluster algebras and Poisson primes for specializations of quantum algebras. The discriminant is a useful invariant for representation theoretic and algebraic study, whose laborious computation deters direct evaluation. The discriminants of quantum Schubert cells at roots of unity will be computed from the two distinct approaches. These methods can be applied to many other quantum algebras.

Hourly Precipitation Climatology Of The Southeast United States, Vincent Brown

LSU Doctoral Dissertations

Precipitation changes are one of the most important potential outcomes of a warming climate because of how essential it is to society and ecosystems. Sub-daily precipitation time series provide more information on precipitation characteristics, particularly frequency, intensity, and duration compared to daily data. In a series of four peer-reviewed manuscripts, this research investigates sub-daily precipitation characteristics from a climatological perspective. The first study introduces a climatology of hourly precipitation for four first-order weather stations across Louisiana, explores possible changes in the hourly precipitation distribution, and links winter Gulf of Mexico sea surface temperatures to the frequency of hours with precipitation. …

Improving Power Network Resilience Against Threats, Hamzeh Davarikia

LSU Doctoral Dissertations

The work reported in this dissertation aims at developing a practical tool for utility transmission planners to improve the power network resilience against high-impact, low-frequency events (HILF). Such events rarely happen, but when occurred are catastrophic. In this dissertation, we studied the impact of HILF from the static and dynamic point of view and proposed the planning strategy to lower the devastating effect of the HILF.

In the static analysis, we consider the steady-state situation of the power grids and plan to protect the grid’s components, i.e., generators, buses, and transmission lines, to maximize preserving demand in a disastrous situation. …

Design Of Metamaterials For Optics, Abiti Adili

LSU Doctoral Dissertations

First part of this dissertation studies the problem of designing metamaterial crystals with double negative effective properties for applications in optics by investigating the conditions necessary for generating novel dispersion properties in a metamaterial crystal with subwavelength microstructure. This provides novel optical properties created through local resonances tied to the geometry of the media in subwavelength regime.

In the second part, this dissertation studies the representation formula used to describe band structures in photonic crystals with plasmonic inclusions. By using layer potential techniques, a magnetic dipole operator describing the tangential component of the electrical field generated by magnetic distribution is …

In Vitro Evaluation Of Ovarian Cancer Tumorigenesis As A Function Of Quinone Oxidoreducatse-1 And Cell Phenotype, Milcah S. Jackson

LSU Doctoral Dissertations

In vitro multicellular spheroids are attractive model systems for assessing genetic and epigenetic changes that occur in diseased tissues. Understanding how such alterations in gene and subsequent protein expression affect disease progression and metastasis, drug resistance, and recurrence is of great interest in cancer research. In this regard, examining expression and activity of proteins, such as those with cytoprotective ability that are overexpressed in cancer cells, in addition to cell phenotype (i.e., stem-like, epithelial, mesenchymal, or mixed), are two ways to evaluate genetic and epigenetic changes. Moreover, determining the impact that cytoprotective proteins and cell phenotype have on tumor formation …

Dehn Functions Of Bestvina-Brady Groups, Yu-Chan Chang

LSU Doctoral Dissertations

In this dissertation, we prove that if the flag complex on a finite simplicial graph is a 2-dimensional triangulated disk, then the Dehn function of the associated Bestvina--Brady group depends on the maximal dimension of the simplices in the interior of the flag complex. We also give some examples where the flag complex on a finite simplicial graph is not 2-dimensional, and we establish a lower bound for the Dehn function of the associated Bestvina--Brady group.

Neurostimulator With Waveforms Inspired By Nature For Wearable Electro-Acupuncture, Jose Aquiles Parodi Amaya

LSU Doctoral Dissertations

The work presented here has 3 goals: establish the need for novel neurostimulation waveform solutions through a literature review, develop a neurostimulation pulse generator, and verify the operation of the device for neurostimulation applications.

The literature review discusses the importance of stimulation waveforms on the outcomes of neurostimulation, and proposes new directions for neurostimulation research that would help in improving the reproducibility and comparability between studies.

The pulse generator circuit is then described that generates signals inspired by the shape of excitatory or inhibitory post-synaptic potentials (EPSP, IPSP). The circuit analytical equations are presented, and the effects of the circuit …

Capturing Contingency: Experimental Documentary In The Wake Of Direct Cinema, Dustin Reed Zemel

LSU Doctoral Dissertations

This dissertation examines experimental works in the late 1960s utilizing technologies and techniques connected with direct cinema and cinema vérité models of documentary filming. Focusing on three experimental filmmakers, I show how films by Jonas Mekas, Robert Fulton and William Greaves eschew the austere style associated with observational realism of direct cinema in favor of more ostentatious experimental assembly practices which highlight the role of the filmmaker as artist. I argue for a relational model of assessment in which documentary film’s qualitative renderings of environment become important determinants of documentary integrity and efficacy. With separate chapters focusing on works by …

Chemosensors Based On Higher Energy Gap Control Of Fluorescence In Conjugated Polymers, Chun-Han Wang

LSU Doctoral Dissertations

Conjugated polymers (CPs) have been widely investigated for their remarkably high sensitivity towards various chemical detection applications. CPs can exhibit effective transduction of certain analyte binding events through changes in fluorescence. These changes include amplified fluorescence quenching ("turn-offmechanism") or an appearance of a fluorescent emission ("turn-onmechanism"). Whereas turn-offsensors can be readily designed and are widely used, amplifying turn-onsensors, from a practical standpoint, are more convenient to use but are more challenging to design.

This dissertation primarily focuses on the development and study of conjugated polymer based amplifying turn-onfluorescence chemosensors utilizing the novel “higher …