Physical Sciences and Mathematics Commons^™

Environmentally Persistent Free Radicals (Epfrs) In Pm₂.₅ : Their Contribution To Hydroxyl Radical Formation And Atmospheric Transformation, William Micheal Gehling, Jr.

LSU Doctoral Dissertations

Previous research demonstrated environmentally persistent free radicals (EPFRs) will form on particulate surfaces under combustion conditions (temperature range of 150-400 °C) from reactions of organic precursors with redox-active transition metals. With an understanding of how these EPFRs form, it is necessary to determine how they behave in a natural environment after emission. To better understand this, the nature of EPFRs in ambient PM2.5 under simulated atmospheric conditions was investigated. Ambient PM2.5 samples were collected at a roadside ambient monitoring site near heavy interstate traffic and major industrial activity. The EPFR concentration and general radical structure were determined with EPR spectroscopy. …

Decade-Scale Nutrient Enrichment Effects On Wetland Plant Community Structure, Function, And Stability, Sean A. Graham

LSU Doctoral Dissertations

Human activities have increased the supply of nitrogen (N) and phosphorus (P) to coastal waters worldwide, threatening coastal wetlands with excess nutrient loading and subsequent eutrophication. In this dissertation, I present results from two decade-scale fertilization experiments in a Sagittaria lancifolia dominated oligohaline marsh that examined the species-, community-, and ecosystem-level effects of nutrient enrichment. My objectives were to determine (1) which nutrient limits primary production, (2) how increased supply of the limiting nutrient affects plant community structure and function, both above- and belowground, and (3) whether nutrient over-enrichment compromises ecosystem stability. Overall, significant changes in plant growth occurred with …

Chemical Composition And Structure Study Of Surfaces And Ultrathin Films Of Complex Compounds, Yi Li

LSU Doctoral Dissertations

Complex Materials, such as transition-metal oxides (TMOs) with exotic properties provide immense opportunities in condensed matter and materials science. The signature and challenge of these materials is the multitude of competing ground states that can be tuned or manipulated by doping, structural modification, strain induction, or the application of external stimulus. In the past few years, it is becoming increasingly clear that surfaces/interfaces, thin films, and heterostructures of TMOs, display a rich diversity of fascinating properties that are related to, but not identical to, the bulk phenomena. The fundamental issues for the understanding of these emergent phenomena include the structure …

Phase Behavior Of Silica-Polypeptide Hybrid Particles Immersed In Cholesteric Liquid Crystals, Melissa Elizabeth Collins

LSU Doctoral Dissertations

Silica-polypeptide hybrid particles are core-shell colloids. Established synthetic methods ensure uniformly sized cores and provide the ability to have magnetic or fluorescent inclusions. The polypeptide shell is highly functional in its ability to respond to stimuli through changes in shape and formation of ordered phases above certain concentrations or temperatures. This research explores the interactions of hybrid particles mixed with polypeptides dispersed in solution. Depletion theory, which considers mainly entropic interactions between particles, can be used to explain the phase behavior of colloids. Due to the chemical similarities between the polypeptides attached to the surface and those free in solution, …

Multiplicity Formulas For Perverse Coherent Sheaves On The Nilpotent Cone, Myron Minn-Thu-Aye

LSU Doctoral Dissertations

Arinkin and Bezrukavnikov have given the construction of the category of equivariant perverse coherent sheaves on the nilpotent cone of a complex reductive algebraic group. Bezrukavnikov has shown that this category is in fact weakly quasi-hereditary with Andersen--Jantzen sheaves playing a role analogous to that of Verma modules in category O for a semi-simple Lie algebra. Our goal is to show that the category of perverse coherent sheaves possesses the added structure of a properly stratified category, and to use this structure to give an effective algorithm to compute multiplicities of simple objects in perverse coherent sheaves. The algorithm is …

Metamorphic And Geochemical Signatures Of Calc-Silicate Gneisses From The Sawtooth Metamorphic Complex, Idaho, Usa : Implications For Crustal Evolution In Western North America, Isis Fukai

LSU Master's Theses

The Sawtooth Metamorphic Complex (SMC) of central Idaho contains exposures of metasupracrustal rocks that may provide constraints on Precambrian crustal evolution in northwestern United States. Petrographic textures, whole-rock geochemistry, and thermobarmetry of SMC calc-silicate gneisses, collected at high-resolution, record multiple stages of crustal development, including: contiguous deposition of a sandstone-to-shale sequence derived from post-Archean continental sediments, metamorphism during two medium-high-grade thermal events (M1, M2), and two distinct episodes of deformation (D1, D2). Whole-rock concentrations of Cr (23.97-76.43 ± 3.0 ppm), Ni (6.82-33.10 ± 3.5 ppm), Th (2.11-12.04 ± 1.6 ppm), Sc (3.81-11.53 ± 1.6 ppm), and Zr (322-658 ± 3.9 …

Studies Of Core-Shell Nanogumbos And Liposomal Ionogels, Ashleigh Renee' Wright

LSU Doctoral Dissertations

The work presented in this dissertation is a description of novel core-shell nanomaterials derived from a group of uniform materials based on organic salts (GUMBOS) and the synthesis and characterizations of novel liposomal ionogels (LIGs). These GUMBOS are an extension of ionic liquids (ILs) which are organic salts with melting points between 25 °C and 100 °C. Ionic liquids have high thermal stability, low vapor pressure, and tunable physiochemical and functional properties. All of the properties of ILs are controlled by the chosen cation and anion pair. Similarly to ILs, GUMBOS possess the same qualities; however, they have melting points …

The Effects Of Implementing The Cooperative Learning Structure, Numbered Heads Together, In Chemistry Classes At A Rural, Low Performing High School, Daniel Paul Baker

LSU Master's Theses

Due to the positive academic results in numerous studies on cooperative learning and the need and desire to improve academic results in East Feliciana High School Chemistry classes, the implementation of a cooperative learning structure called “numbered heads together” was studied during the spring 2013 semester at this rural, low performing high school. Numbered heads together was utilized during three units of a Chemistry class with 24 students and three units of an AP Chemistry with 11 students after completion of two units taught without the use of any type of cooperative learning structure. Using pre- and post-tests, learning gain …

Fraction Proficiency And The Number Line, Jeanne Elizabeth Bass

LSU Master's Theses

The Common Core State Standards place special emphasis on developing fraction proficiency and the use of the number line, especially in grades three through five, whereas the previously mandated “Louisiana Comprehensive Curriculum” put lower priority on fractions and gave little attention to the number line as a model for fractions. The present study was performed in several 6th-grade math classrooms in rural Louisiana. We piloted fraction proficiency tests that were intended to check basic vocabulary and student access to various fraction models, as expected in the Common Core. Some strong error patterns were observed. They might be related to difference …

Spectral Breast Ct : Effect Of Adaptive Filtration On Ct Numbers, Ct Noise, And Ct Dose, Justin Silkwood

LSU Master's Theses

Purpose: Adaptive filtration facilitates spectral breast CT by decreasing count rate and dynamic range requirements of photon counting detectors. This project investigated the effect of adaptive filtration on beam hardening, CT numbers, noise, and dose in dedicated breast CT. Methods: Adaptive filters were simulated to provide a flat fluence at the detector surface when used with a 14 cm breast phantom at 120 kVp. Beam hardening with each filter type was measured against increasing x-ray beam half-fan angle.. Breast CT images were simulated with and without an adaptive filter in the beam at multiple tube voltages. CT number, noise, and …

Uncertainty Quantification Of Film Cooling Effectiveness In Gas Turbines, Hessam Babaee

LSU Master's Theses

In this study the effect of uncertainty of velocity ratio on jet in crossflow and particual- rly film cooling performance is studied. Direct numerical simulations have been combined with a stochastic collocation approach where the parametric space is discretized using Multi-Element general Polynomial Chaos (ME-gPC) method. Velocity ratio serves as a bifurcation parameter in a jet in a crossflow and the dynamical system is shown to have several bifurcations. As a result of the bifurcations, the target functional is observed to have low-regularity with respect to the paramteric space. In that sense, ME-gPC is particularly effective in discretizing the parametric …

Lost In Translation : Algebraic Modeling In The Middle School Classroom, Danielle Denise Ricks

LSU Master's Theses

This study was conducted to investigate the disparity that seems to exist in students’ abilities to solve equations, solve word problems, and model word problems with algebraic equations. Over the course of fourteen-weeks, students enrolled in an advanced seventh grade mathematics course were given a series of algebra assignments, tasks, and surveys that focused on students’ abilities to solve and write algebraic equations. The results show that students are more competent in determining solutions for equations and simple word problems than modeling word problems with algebraic equations. Students were willing to exert substantial effort to use arithmetic procedures to find …

The Effects Of Self-Examination To Peers On Student Learning In Physical Science, Leah Ellis Thompson

LSU Master's Theses

This study was undertaken to test if the use of self-explanation to a peer would affect learning outcomes in the classroom. The outcomes of classes taught using the self-explanation technique were compared to outcomes from traditional lecture courses in lessons of comparable content. Great Scholars and traditional students in a sixth grade physical science classroom setting were given pre-and post-tests in two units of study, matter and waves. In the matter unit, students participated in a lesson on density using traditional lecture and a lesson on changes in matter using self-explanation. In the waves unit, students utilized lecture instruction for …

Inertial Oscillations In The Gulf Of Mexico During 2005 Hurricane Season, Fan Zhang

LSU Master's Theses

Near Inertial Oscillations (NIOs) are widely observed in ocean current data after severe weather. In this work, we analyzed the NIOs in the Central Gulf of Mexico (GoM) associated with 6 hurricanes/tropical storms in 2005, including Katrina and Rita, based on the deep ocean mooring from Coastal Studies Institute (CSI), LSU. The basic characteristics of the NIOs, such as phase speed, group speed, frequency, energy were discussed. The phase speed ranged from 0.56 cm/s to 2 cm/s above the thermocline for the NIOs during Hurricane Katrina and Rita, while the group velocity varied from 0.047 cm/s above the thermocline to …

The Reduction And Reoxidation Of Ceria : A Natural Abundance Oxygen Isotope Approach, Justin Alan Hayles

LSU Master's Theses

Ceria (CeO2) is a fluorite type oxide that has been used extensively as an oxygen storage media in three-way catalysts, as an oxygen partial pressure regulator, as a fuel additive for the reduction of soot and for the production of syn-gas from water and carbon dioxide. It is known that exposing ceria powders to low pO2 and/or high temperature conditions will cause ceria to partially reduce. This partial reduction leads to the formation of oxygen vacancies, which up to a limit, do not significantly influence the crystal structure. When partially reduced ceria is exposed to high pO2 environments, such as …

Detection Of Interesting Traffic Accident Patterns By Association Rule Mining, Harisha Donepudi

LSU Master's Theses

In recent years, the accident rate related to traffic is high. Analyzing the crash data and extracting useful information from it can help in taking respective measures to decrease this rate or prevent the crash from happening. Related research has been done in the past which involved proposing various measures and algorithms to obtain interesting crash patterns from the crash records. The main problem is that large numbers of patterns were produced and vast number of these patterns would be obvious or not interesting. A deeper analysis of the data is required in order to get the interesting patterns. In …

Large Deviations For Stochastic Navier-Stokes Equations With Nonlinear Viscosities, Ming Tao

LSU Doctoral Dissertations

In this work, a Wentzell-Freidlin type large deviation principle is established for the two-dimensional stochastic Navier-Stokes equations (SNSE's) with nonlinear viscosities. We fi_x000C_rst prove the existence and uniqueness of solutions to the two-dimensionalstochastic Navier-Stokes equations with nonlinear viscosities using the martingale problem argument and the method of monotonicity. By the results of Varadhan and Bryc, the large deviation principle (LDP) is equivalent to the Laplace-Varadhan principle (LVP) if the underlying space is Polish. Then using the stochastic control and weak convergence approach developed by Budhiraja and Dupuis, the Laplace-Varadhan principle for solutions of stochastic Navier-Stokesequations is obtained in appropriate function …

Temperature And Pressure Conditions Of Archean Amphibolite-Granulite Facies Metamorphic Xenoliths From The Eastern Beartooth Mountains, Montana And Wyoming, Usa, Celina N. Will

LSU Master's Theses

Compositionally-diverse Archean metamorphic rocks occur as xenoliths within the well-dated 2.8 Ga granitic gneisses that volumetrically-dominate the eastern Beartooth Mountains of the northern Wyoming Province. Common mafic lithologies in the Quad Creek-High Line Trails-Christmas Lake-Wyoming Creek-Line Creek Plateau area include granitic gneiss, amphibolites, mafic granulites and biotite and garnet-bearing peraluminous gneisses. The region also has sillimanite-biotite ± cordierite ± garnet gneisses and migmatites, as well as a single occurrence of a noteworthy orthopyroxene-cordierite gneiss with late-stage anthophyllite. A combination of detailed petrographic analysis and thermobarometric modeling were used to constrain the metamorphic conditions of the xenoliths prior to inclusion in …

The Effects Of The Peer Instruction Technique Think-Pair-Share On Students' Performance In Chemistry, Kathleen Sipos Trent

LSU Master's Theses

Think-Pair-Share is an active learning strategy which involves pairs of students discussing answers to questions or problems. The purpose of this study was to determine if the peer instruction technique Think-Pair-Share improved students’ performance in high-school chemistry. The teacher used one class of students as a control group. This group did not use Think-Pair-Share for the chapter investigated, “Chemical Reactions”. The teacher used two other classes of students, who did use Think-Pair-Share for this chapter, as the experimental group. There was no difference in the learning gains between the control and experimental groups. Think-Pair-Share and normal classroom instruction methods were …

Contractional Tectonics : The Himalayan Orogen And Perdido Fold-Thrust Belt, Dian He

LSU Doctoral Dissertations

This dissertation focuses on the kinematic evolution of two major categories of contractional tectonics: collisional orogenic belts and toe structures of passive margins, which are characterized by fold-thrust belts that are hundreds of kilometer-scale and tens of kilometer-scale, respectively. The Himalayan orogen is an excellent example of collisional orogenic belts along convergent plate boundaries. It is commonly structurally defined as three stacked units separated by two fault systems: the Main Central thrust (MCT) and South Tibet detachment (STD). The development and emplacement of the middle unit, the Himalayan crystalline core, has long been debated within the extrusion framework, a process …

A Microfluidic Bacteria Culturing Device With Maldi Mass Spectrometry Detection, Pratap Reddy Machavaram Siva

LSU Master's Theses

A novel microfluidic device was developed for bacterial cell culturing using mass spectrometry as the detector. One of the challenges in proteomics is to achieve high sensitivity in the identification of proteins in complex samples with widely varying concentrations. The main limitations for proteomic studies are relatively slow and labor-intensive steps such as cell culturing and protein digestion of small sample quantities. Microfluidics is a promising approach to increase throughput and to reduce the time-consuming steps that are necessary for proteomics. When an analytical detection method is combined with microfluidics it can overcome limitations that are important in the analysis …

Parallel Suffix Tree Construction For Genome Sequence Using Hadoop, Umesh Chandra Satish

LSU Master's Theses

Indexing the genome is the basis for many of the bioinformatics applications. Read mapping (sequence alignment) is one such application to align millions of short reads against reference genome. Several tools like BLAST, SOAP, BOWTIE, Cloudburst, and Rapid Parallel Genome Indexing with MapReduce use indexing technique for aligning short reads. Many of the contemporary alignment techniques are time consuming, memory intensive and cannot be easily scaled to larger genomes. Suffix tree is a popular data structure which can be used to overcome the demerits of other alignment techniques. However, constructing the suffix tree is highly memory intensive and time consuming. …

A Secondary Monitor Unit Calculation Algorithm Using Superposition Of Symmetric, Open Fields For Imrt Plans, Adam Michael Watts

LSU Master's Theses

Purpose: To perform a secondary dose calculation for intensity modulated radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT) plans to a point on or off axis within 2% using open field data.
Methods: An independent dose calculation algorithm has been developed for complex fields with multiple segments. The algorithm subdivides dose into the contributions from each opposing leaf pair for a given multileaf collimator (MLC) configuration. Leaf pair dose is determined by drawing four rectangular fields based on leaf positions, which are symmetric about the point of calculation. Superposition of these fields yields the dose from the leaf pair to …

Evaluating Abiotic Influences On Soil Salinity Of Inland Managed Wetlands And Agricultural Fields In A Semi-Arid Environment, Drew Nathan Fowler

LSU Master's Theses

Agriculture and moist-soil management are important management techniques used on wildlife refuges to provide adequate energy for migrant and wintering waterbirds. However, in arid systems, the presence and accumulation of soluble salts throughout the soil profile can limit total biomass production of wetland plants and agronomic crops and thus jeopardize meeting waterbird energy needs. It is unknown how moist-soil management and traditional agriculture practices influence the accumulation and distribution of soluble salts of soil profiles. In this study of an arid wetland ecosystem, I determine: 1) the effect of long-term, distinct surface hydrologic regimes associated with moist-soil management and agricultural …

Evaluating Quaternary Glacial Till Sheet Volume And Duration Of Grounding Events Using Sediment Flux Calculations In The Eastern Basin Paleotroughs, Ross Sea, Anarctica, Logan Gregory Kirst

LSU Master's Theses

A sequence of three seismically-resolvable, back-stepping grounding zone wedges (GZWs) within the Glomar-Challenger Basin paleo-ice-stream trough is conventionally interpreted to have been deposited by the West Antarctic Ice Sheet (WAIS) since the end of the Last Glacial Maximum (LGM). For this to be true, there would have to have been voluminous GZW deposition via fast moving ice streams with high sediment flux during the short timeframe since the WAIS retreat began at 11 Ka 14C BP and when the WAIS moved south of Roosevelt Island at 3.2 Ka BP. In contrast to this interpretation of how the near-surface stratigraphy relates …

Energy Spectra Comparisons For Matched Clinical Electron Beams On Elekta Linear Accelerators Using A Permanent Magnet Spectrometer, David Mclaughlin

LSU Master's Theses

Purpose: The purpose of this work was to use a permanent magnet electron energy spectrometer to measure and compare electron beam energy spectra from matched electron beams on Elekta radiotherapy accelerators at Mary Bird Perkins Cancer Center

Methods: Electron beamcollimation, X-ray background collimation, and irradiation geometry were developed to produce suitable latent images in computed radiography (CR) strips at the exit side of a 0.5-Tesla permanent magnet spectrometer.An analytical technique transformed CR strip images into energy spectra on central axis at 95-cm source-to-collimator distance.Electron energy spectra at 7, 9, 10, 11, 13, 16, and 20 MeV for four accelerators, whose …

Impacts And Recovery Of The Deepwater Horizon Oil Spill On Vegetation Structure And Function Of Phragmites Australis, Chad Robert Judy

LSU Master's Theses

Abstract The aim of this study was to determine the impacts of the Deepwater Horizon (DWH) oil spill on the common reed Phragmites australis, and the processes controlling species effects and recovery, via a greenhouse mesocosm study. In the greenhouse DWH source oil, weathered approximately 40% by weight and emulsified, was applied to the aboveground shoots of P. australis growing in marsh sods to produce the following treatment-levels: (1) oil coverage of the lower 30% of shoot-height, (2) the lower 70% of shoot-height, (3) repeated oil coverage of the lower 70% of shoot-height, (4) 100% oil coverage of shoots, (5) …

Quantification Of Total And Oil-Degrading Bacteria In Louisiana Marsh Sediment Following The Deepwater Horizon Oil Spill Using Cultivation And Real-Time Pcr Assays, Kristopher Nolan Ackoury

LSU Master's Theses

Although the impacts of the Deepwater Horizon (DWH) oil spill on the bacterial communities in several Gulf of Mexico habitats have been described, little if any research has been published evaluating the impacts of the spill on bacterial populations in the most severely oiled salt marsh soils of Barataria Bay, Louisiana. The aim of this study was to define the effects of the spill on the total and oil-degrading bacterial communities in these marshes. Using quantitative real-time PCR (qPCR) and traditional cultivation methods bacterial communities from contaminated marsh soils were examined thirteen, twenty-two, and twenty-nine months after the initial oiling …

Evaluation Of An Automated Delivery Verification System For Volumetric Modulated Arc Therapy Treatments, John-Paul Grenier

LSU Master's Theses

Purpose: The purpose of this work was to evaluate the ability of a treatment delivery verification system to detect clinically significant mechanical errors in VMAT delivery utilizing data contained within a commercial record and verify (RV) system, and to test whether the system can be used to reconstruct dose distributions that agree more closely with measured dose distributions than do the original treatment plans. Methods: VMAT treatment plans from five prostate patients, five head and neck patients, and five post-mastectomy chest wall patients treated at our clinic were selected for this study. Known mechanical errors were introduced into each plan, …

The Development Of An Ac Magneto- Optic Kerr Effect System For The Characterization Of Pulsed Laser Deposited Co₂Mnsi-Xal1-X Heusler Alloy Thin Films, Matthew Stephen Champagne

LSU Master's Theses

The Kerr rotation and Kerr ellipticity of thin films can be measured using an AC magneto-optic Kerr effect (AC-MOKE) system. The longitudinal MOKE measurements were taken for a series of Co2MnSixAl1-x thin films with values of x= 0.00, 0.25, 0.50, 0.75, 1.00. The films were fabricated using ultra high vacuum, pulsed laser deposition (PLD) techniques. The PLD targets were made using conventional arc-melting techniques. Using a Jones matrix analysis, it was shown that the Kerr rotation and Kerr ellipticity can be measured separately using two optical setups by taking advantage of a photoelastic modulator and lock-in techniques. Co2MnAl and Co2MnSi …