Physical Sciences and Mathematics Commons^™

Design Of A Passive Intensity Modulation Device For Bolus Electron Conformal Therapy, Erin Leanne Chambers

LSU Master's Theses

Purpose: To develop a process that can design an island block matrix that produces an intensity distribution (70-100%), which acceptably matches one planned for an intensity modulated (IM) bolus electron conformal therapy (ECT) patient. The intensity modulator concept is that electrons laterally scatter behind hexagonally-packed, small-diameter island blocks such that local intensity equals the fractional unblocked area.

Methods: A pencil beam algorithm (PBA) was used to calculate the modulated electron intensity created by varying diameter (d) of island blocks in a hexagonal array (separation r). Accuracy of the PBA model was assessed by comparing with Monte Carlo (MC) calculations. PBA …

The Effect Of Artificial Light On The Community Structure And Distribution Of Reef-Associated Fishes At Oil And Gas Platforms In The Northern Gulf Of Mexico, Victoria Anne Barker

LSU Master's Theses

The northern Gulf of Mexico (GOM) contains approximately 2,500 oil and gas platforms, resulting in one of the largest de facto artificial reef systems in the world. As of 2013, 1,227 additional structures had ceased to produce oil and gas and have been decommissioned and removed. While active platforms are lit by high-pressure mercury vapor lights, inactive platforms are only minimally lit for navigation. The positively phototaxic behavior of many fish species causes lit oil platforms to act as fish attraction devices, especially at night. Though a variety of fish species have been reported near these structures, changes in fish …

Influences On The Successful Implementation Of The Convention On Wetlands Of International Importance (Ramsar) Among Member Countries, Aziza Saud Al Adhoobi

LSU Master's Theses

Wetlands are very dynamic ecosystems and are featured all over the world’s landscape. Recent studies suggested that wetlands are in continuous decline, both and quantity and quality and between 64-71% is the estimated global wetland loss in the 20th century (Davidson 2014; Gardner et al., 2015). Therefore, as wetland loss increases around the world, more effort to protect and restore wetland habitat, values, and services become crucial. For this reason, the Ramsar Convention was established four decades ago to highlight the severity of wetland loss and to produce guidelines that aim to guide Contracting Parties toward sustainable and efficient management …

Feeding Ecology Of Red Snapper And Greater Amberjack At Standing Platforms In The Northern Gulf Of Mexico: Disentangling The Effects Of Artificial Light, Kristin Leanne Foss

LSU Master's Theses

Approximately 2,300 petroleum platforms are currently operating in the Gulf of Mexico (GOM), and are estimated to provide an additional 4 to 12 km2 of artificial reef habitat. The ecological role of platforms has often been overlooked and little is known about the effect of artificial light from the active platforms on surrounding fish communities. This is the first study to address the potential impacts of artificial light on the trophic ecology of fish communities surrounding offshore platforms through gut content (GCA) and stable isotope (SIA) analyses. Red snapper (Lutjanus campechanus) were collected quarterly from February 2014 to November 2015 …

A Geochronological And Stratigraphic Reconstruction Of The Middle Barataria Bay Receiving Basin, Joseph Ethan Thomas Hughes

LSU Master's Theses

Barataria Bay, one of the largest receiving basins for the Mississippi deltaic complex, is the location of a proposed river-sediment diversion for delta restoration. In order to determine how the sediment in the receiving-basin may respond to diversion flows, twenty-five sediment vibracores were collected from a 115 km2 study area located near Myrtle Grove and Bayou Dupont, southeast of New Orleans, LA. These cores were subject to multiple tests, including gamma bulk density scans, grain size analysis, and loss-on-ignition, in order to identify the lithology and stratigraphy. In addition, 137Cs and 14C dating techniques were employed in order to construct …

Comparison Of Group Size, Abundance Estimates And Movement Patterns Of Common Bottlenose Dolphins (Tursiops Truncatus) In Mississippi Sound, Mississippi, Carrie Sinclair

LSU Master's Theses

Common bottlenose dolphins (Tursiops truncatus; dolphins) inhabiting Mississippi Sound (MSS) in the north-central Gulf of Mexico (GMx) are considered a part of a single stock of dolphins that includes Bay Boudreau and Lake Borgne by the National Marine Fisheries Service (NMFS). MSS is bounded by the mainland (north) and several barrier islands (south). Dolphins inhabiting coastal waters directly south of the barrier islands constitute part of the Northern Coastal Stock. Abundance in MSS has been reported to fluctuate seasonally, with higher abundances of dolphins estimated in summer versus winter. Analysis of covariance was used to compare previous abundance estimates. Results …

In Situ Geochemistry Of Middle Ordovician Dolomites Of The Upper Mississippi Valley: Evaluation Of The Dorag Model And New Implications For Dolomitizing Fluids, John Michael Callen

LSU Master's Theses

The dolomitization and diagenetic history of Ordovician carbonates of southern Wisconsin has been studied for over a century. Previous studies attributed dolomitization to various single or multiple diagenetic factors and environments. The goal of the study was to resolve arguments regarding dolomitization models, including Badiozamani’s often cited but recently questioned mixing zone model, using LA-ICP-MS focusing on REE to determine the nature of dolomitizing fluids. Analysis revealed that particulate material incorporated into the dolomite affected the geochemical results of many of the samples. Integrating geochemical data with petrographic evidence for diagenetic history, the studied Decorah Formation dolomites were assigned to …

A Contemporary Approach To A Classic Model: Exploring The Influence Of Local Interactions And Disturbance On Mangrove Forest Dynamics With A Spatially-Explicit Version Of Forman, Kieley Shannon Hurff

LSU Master's Theses

The mangrove forest gap dynamic model, FORMAN, was the first individual-based model (IBM) to simulate the long-term successional dynamics of three Caribbean mangrove species, Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle. Assumptions under the spatially implicit approach of gap dynamic models limit their application to small-scale simulations. An expanded, spatially-explicit version of FORMAN was developed to allow for simulations of larger spatial grids, through the inclusion of localized soil conditions and neighborhood-based light resource competition. This expanded model was used to investigate the influence of localized interactions and disturbances of varying size on forest dynamics. A data-model comparison using field …

The Effect Of Restoration On Nitrate Reduction And Biogeochemical Functioning In Louisiana Wetlands: Bottomland Hardwood Forests And Deltaic Sediments, Nia R. Hurst

LSU Master's Theses

Nitrogen loading in the Mississippi River from increased N fertilization of agricultural land helps to trigger an area of hypoxic water in the northern Gulf of Mexico (GOM) every summer. Louisiana wetlands can play a vital role in removing nitrate from river waters prior to discharge in the GOM. However, Louisiana’s wetlands have experienced significant losses in recent years. Efforts to restore wetlands include reconnecting floodplain wetlands to rivers and utilizing river diversions to re-introduce sediment to coastal wetlands. Increasing wetland connection to rivers can reduce water nitrate by expanding opportunities for nitrate reduction. I examined soil physicochemical properties, microbial …

Social Media Network Data Mining And Optimization, Neha Clare Jose

LSU Master's Theses

Many small social aid organizations could benefit from collaborating with other organizations on common causes, but may not have the necessary social relationships. We present a framework for a recommender system for the Louisiana Poverty Initiative that identifies member organizations with common causes and aims to forge connections between these organizations. Our framework employs a combination of graph and text analyses of the organizations' Facebook pages. We use NodeXL, a plugin to Microsoft Excel, to download the Facebook graph and to interface with SNAP, the Stanford Network Analysis Platform, for calculating network measurements. Our framework extends NodeXL with algorithms that …

Using Tourmaline As An Indicator Of Provenance: Development And Application Of A Statistical Approach Using Random Forests, Erin Lael Walden

LSU Master's Theses

Tourmaline is a petrologic indicator mineral that is the major repository of boron in the earth’s crust. It forms readily when boron is present, accommodating multiple cations and anions with multiple possible substitutions for each site in the crystal structure. It is stable over a wide variety of pressures and temperatures, from near-surface P/T conditions to greater than 950 C and 7 GPa. It records information about conditions of formation, as well as pressure and temperature. Due to its resistance to chemical or physical weathering, and the negligible diffusion of elements in the crystal lattice, information about provenance is preserved. …

Living On The Edge: An Assessment Of The Habitat Use Of Waterbirds In Estuarine Wetlands Of Barataria Basin, La, Brett Ashley Patton

LSU Master's Theses

The wetlands of Louisiana are losing area at the rapid rate of 42.9 km2 yr-1 and the trend is expected to continue. This combined with expected sea-level rise will likely cause large shifts in vegetation and salinity regimes that will affect the wildlife species reliant on these ecosystems. Waterbirds serve as indicator species of ecosystem health in estuarine wetland habitats; therefore, these species are often the targets of wetland management goals in Louisiana. However, many proposed wetland restoration projects are focused primarily on social impacts with only a few specific waterbird species designated for management. The majority of these waterbird …

Interplay Effects In Highly Modulated Stereotactic Body Radiation Therapy Lung Cases Treated With Volumetric Modulated Arc Therapy, Desmond Joseph Fernandez

LSU Master's Theses

Purpose: To evaluate the influence of tumor motion on dose delivery in highly modulated stereotactic body radiotherapy (SBRT) of lung cancer using volumetric modulated arc therapy (VMAT). Methods: 4D-CT imaging data of the quasar respiratory phantom were acquired, using a GE Lightspeed 16-slice CT scanner, while the phantom reproduced patient specific respiratory traces. Flattening filter-free (FFF) dual-arc VMAT treatment plans were created on the acquired images in Pinnacle3 treatment planning system. Each plan was generated with varying levels of complexity characterized by the modulation complexity score. Static and dynamic measurements were delivered to GafChromic EBT3 film inside the respiratory phantom …

Study Of Resistivity And Shear Wave Velocity As A Predictive Tool Of Sediment Type In Levee Foundation Soils, Louisiana Gulf Coast Levee System, Derek Stephen Goff

LSU Master's Theses

Geotechnical sediment type of levee foundation soils may be estimated by using cross-plots of shear-wave velocity and electrical resistivity for Louisiana levees. Best-fit polynomial models for estimating soil type in Japanese levees have been created using cross-plots of shear-wave velocity and electrical resistivity. A similar study or model for flood protection structures in the Mississippi River delta plain or other major river delta does not exist. We make the soil-type estimation model more relevant to the foundation soils in the Louisiana Coastal Zone by identifying silt in addition to sand and clay, and eliminating gravel as a dominant soil type. …

An Empirical Estimate Of Post-Lgm Grounding-Event Duration In Eastern Ross Sea: Implications From A Comparison With Constraints From New Radiocarbon Dates, Benjamin Krogmeier

LSU Master's Theses

The West Antarctic Ice Sheet (WAIS) advanced to the outer shelf during the Last Glacial Maximum (LGM) before beginning a rapid retreat to the inner shelf. In the Whales Deep paleo-ice-stream trough, subsurface and geomorphologic evidence shows that grounding-line retreat was interrupted by at least five pauses in the area between the shelf edge and the middle shelf. During the pauses, an overlapping cluster of backstepped grounding zone wedges (GZWs) was deposited. Each GZW represents a grounding event, i.e., a time interval during which the grounding-line position was relatively stable. Seismic correlation and isopach mapping show that the cluster has …

Archean Geodynamic Conditions Using P-T Constraints Of The East Pilbara Craton Ttgs, Andrew Kody Webb

LSU Master's Theses

We know very little about the tectonic setting present during the Hadean, but based on studies of surviving Hadean zircons, we know that a Hadean protocrust must have been established by at least 4.4 Ga (Kemp et al. 2010), and it must have also been able to accommodate minimum melt conditions (Harrison 2005). Tectonic models for Earth during the Hadean and Archean follow two trends: uniformitarianism and non-uniformitarianism. Uniformitarian models (following the famed geological concept that the present is the key to the past) argue that Hadean zircons and Archean rocks formed via processes akin to modern-style oceanic crust production …

Applying Deep Learning Techniques To The Analysis Of Android Apks, Robin Andrew Nix

LSU Master's Theses

Malware targeting mobile devices is a pervasive problem in modern life and as such tools to detect and classify malware are of great value. This paper seeks to demonstrate the effectiveness of Deep Learning Techniques, specifically Convolutional Neural Networks, in detecting and classifying malware targeting the Android operating system. Unlike many current detection techniques, which require the use of relatively rigid features to aid in detection, deep neural networks are capable of automatically learning flexible features which may be more resilient to obfuscation. We present a parsing for extracting sequences of API calls which can be used to describe a …

Relative Resistance To Breaking Of Pinus Taeda L. And Pinus Palustris, Cory Glenn Garms

LSU Master's Theses

Patterns from hurricane damage give an indication that longleaf pine (Pinus palustris) is more windfirm than loblolly pine (Pinus taeda). Tree windfirmess has been attributed to many factors including species and material properties like wood strength and stiffness. Because longleaf pine wood is stronger and stiffer than loblolly pine wood, this study used static winching methodology to see if these properties account for differences in windfirmness by measuring bending force required to break stems (MMAX). Stress-strain diagrams were constructed for pulled trees to explore how they behave under increasing loads. Based on these diagrams, it appears that living trees can …

Infectivity And Physiological Effects Of White Spot Syndrome Virus (Wssv) In Farmed Louisiana Red Swamp Crayfish (Procambarus Clarkii), Barcley Talon Pace

LSU Master's Theses

The red swamp crayfish, Procambarus clarkii, represents an important aquaculture species responsible for over half of all commercial aquaculture profits in Louisiana. White spot syndrome virus (WSSV) is highly pathogenic and induces mass mortality in crustacean aquaculture operations worldwide. Crayfish lack the adaptive ability of the vertebrate immune system, and must depend on primitive, innate immune responses to combat viral infections. This study aims to investigate the dose-response of WSSV in P. clarkii and to examine viral-host interactions by examining the biochemical and immunological changes induced by WSSV infection in this species. Viable viral particles were isolated from naturally infected …

Effects Of Landscape Fragmentation On Land Loss, Weijia Cheng

LSU Master's Theses

Coastal Louisiana, the seventh largest delta on earth, is one of the most vulnerable coastal areas in the United States of America (USA) because of its land loss problem. Coastal land loss is usually caused by many complicated factors. With the rapid increase in human activities, more studies on land loss have focused on the anthropogenic elements, but less on the pattern of the landscape. It is expected that the type of spatial arrangement, such as high degree of fragmentation, would affect the degree of land erosion. A quantitative evaluation of coastal landscape fragmentation and its influences on land loss …

Investigating Species And Population Level Foraging Variation And Individual Specialization In Pygoscelis Penguins Using Stable Isotope Analysis, Rachael W. Herman

LSU Master's Theses

Gentoo Penguins (Pygoscelis papua) are known to be generalist foragers, while Adélie (P. adeliae) and Chinstrap (P. Antarctica) tend to specialize on krill within the Western Antarctic Peninsula and South Shetland Islands, particularly during the breeding season. However, little is known on temporal consistency in diet and foraging habitat of these species, particularly at the individual level. We used stable isotope analysis (SIA) of blood and feathers to evaluate seasonal and individual foraging consistency within Adélie, Chinstrap and Gentoo Penguins breeding in the South Shetland Islands, as well as among three Gentoo Penguins’ populations in the Western Antarctic Peninsula and …

Spatiotemporal Distribution Of The Himalayan Leucogranite: Implications For Mountain-Building As A Function Of Indian Slab Dynamics, Hongcheng Guo

LSU Master's Theses

The Himalayan orogen, as a natural laboratory for continental collision, has attracted intense research attention for decades. However, the question of how the orogen was built is still debated, and potential answers are few when considering how and why along-strike variations of the mountain-building processes occurred. Various tectonic models have been proposed to explain the kinematics of the mountain-building. These models include two dimensional models, such as wedge extrusion (Burchfiel and Royden, 1985; Grujic et al., 1996; Kohn, 2008), channel flow coupled to focused denudation (Beaumont et al., 2001; Hodges et al., 2001), tectonic wedging (Yin, 2006; Webb et al., …

Simulating Behavioral Microcystin Impairment In Fish, Nicholas Richard Keeney

LSU Master's Theses

Fish experiencing blooms of the cyanobacteria genera Microcystis and Anabaena acquire microcystin and saxitoxin through ingestion of contaminated food and absorption of dissolved toxin. Even low chronic doses induce sensory and motor impairment—the impact of which is unquantified in wild populations. Here, I introduce Lagrangian particle models for cyanobacteria and fish which test the hypotheses that impairment symptoms suppress movement and growth. This is implemented within the Finite-Volume Coastal Ocean Model (FVCOM). Cyanobacteria particles move vertically according to mixing and buoyancy (a function of cellular reservoirs). Fish navigate the horizontal domain, foraging in high growth areas, and fleeing when toxin …

The Role Of Upper Ocean Heat Content And Sea Surface Temperature On Northeast Pacific Hurricane Evolution During Average And Active Years, Victoria Lauren Ford

LSU Master's Theses

Upon comparison to typical neutral-ENSO conditions in the Northeast Pacific Ocean, the 2014 hurricane season has been identified as highly anomalous in both tropical cyclone frequency and intensity. This thesis seeks to investigate the influence of sea surface temperatures (SSTs) and upper ocean heat content (UOHC), defined as the excess of heat present above 26°C, upon the upper ocean thermal structure, mesoscale features, and anomalies that led to an active hurricane season in the Northeast Pacific. The 2012 Northeast Pacific hurricane season was selected as a ‘normal’ season to fully quantify the anomalous 2014 hurricane season. Data sets utilized in …

Fishes Associated With Oil And Gas Platforms In Louisiana's River-Influenced Nearshore Waters, Ryan Thomas Munnelly

LSU Master's Theses

A distinctive feature of coastal Louisiana is the unrivaled network of oil and gas installations (platforms) extending from inshore waters to the deep Gulf of Mexico. Since 2007 there has been a 38% reduction in platform numbers with the highest removal rates occurring in shallow (< 18 m) nearshore waters. Many fishes and invertebrates are attracted to platforms, presenting a unique opportunity to study detailed species-specific responses to the river-influenced hydrographic characteristics of Louisiana’s nearshore zone (5–25 km water depth). Prior studies of fishes around platforms focused on a few relatively large platforms in water depths ≥ 18 m. However, about one-third of all platforms are small, unmanned and non-drilling platforms located in waters < 18 m depth. Paired video and hydrographic data were collected at 150 small platforms in < 18 m water depth during the summers of 2013–2014. Fifty-four species of fishes were associated with small platforms. The assemblage(s) included juveniles of 29 species, indicating the importance of nearshore platforms as diverse nursery habitat. The coastal zone was divided into three regions based on broad-scale interactions between freshwater input and bathymetry driving major distinctions in interregional hydrography and fish assemblages. Co-occurring within this expansive artificial reef network is the second largest hypoxic area (dissolved oxygen (DO) < 2.0 mg l−1) on Earth. Platforms offer reef-like habitat features in the upper water column that may offer refugia for some reef-associated species during hypoxic events. Significant intraregional differences in physicochemical features were related to the presence of hypoxia (defined as DO < 50% saturation), as well as the distribution of sandy shoals. Eleven species accounted for most of the assemblage dissimilarities, composing ~93% of fishes observed. Habitat suitability indices for these 11 species provided information about habitat selection across horizontal and vertical physicochemical gradients throughout the coastal zone, and within hypoxic and well-oxygenated stratified water columns. East Bay, near the outlet of the Mississippi River, exhibited less hypoxia and a distinct fauna that included four adult goliath grouper (Epinephelus itajara). This endangered fish was observed during spawning season (summer), suggesting that East Bay might support a spawning aggregation.

Methodologies Utilizing Protected Oxyallyl Cations For Molecular Design, Jacob Reuben Stepherson

LSU Master's Theses

This master’s thesis discusses developments of novel organic methodologies utilizing oxyallyl cationic systems in the pursuit of highly functionalized molecular scaffolds. Chapter 1 focuses on the discovery of the oxyallyl cation intermediate, and examines reported transformations. Detailed optimization and substrate studies following exploitation of a protected 2-oxyallyl cation for nucleophilc capture comprises the information in both Chapter 2 and Chapter 3. Chapter 4 extends methodologies performed by my colleagues and establishes a tandem process using 2-silyloxypentadienyl cations to furnish complex structures. In this report, reaction design and optimization are chronicled, followed by exploration into the reactivity, mechanism, and scope of …

Pesticide Partitioning In Louisiana Wetland Aand Ricefield Sediment, Brendan Michael Marsh

LSU Master's Theses

Pesticides are used globally and are often found within bodies of water. The EPA investigates the potential environmental impact through computer modeling in order to help mitigate some of the regulatory burden of pesticide fate investigation. Currently when pesticides enter a water body, the Exposure Analysis Modeling System (EXAMS) estimates partitioning depth as 5 cm and assumes equal distribution. This assumption was tested with a wide variety of pesticides with varying Koc ranges and water solubilities. Savillex 150 ml Teflon tubes were filled with wetland and ricefield sediments with fresh and seawater as the aqueous phase. The seven pesticides tested …

Characterization And Modeling Of Sediment Settling, Consolidation And Suspension To Optimize The Retention Rate Of Sediment Diversions For Coastal Restoration, Xiaoyu Sha

LSU Master's Theses

Many research efforts have been made to the Mississippi coastal restoration, but long-term rheological and sedimentological experiments for sediment erosion, deposition and consolidation in diversion receiving basins are still lacking. Push cores and sediment samples were collected from West Bay, a semi-enclosed bay located on the Mississippi River Delta, and Big Mar pond, a receiving basin of the Caernarvon freshwater diversion from the Mississippi River, Louisiana. A dual-core Gust Erosion Microcosm System was used to measure time-series (0.5, 1, 2, 3, 4, 5, and 6-month after initial settling) erodibility at seven shear stress regimes (0.01-0.60 Pa) using experimental cores prepared …

Interactions Among Hydrology, Sediment And Vegetation In Accreting Wax Lake Delta: Physical And Biogeochemical Implications For Coastal Louisiana Restoration, Courtney Erin Elliton

LSU Master's Theses

River discharge pulses, wind, waves, tides, and the presence of dense vegetation are factors that interact and regulate the transport and retention of sediment in coastal regions. In particular, vegetation structural and physiognomic traits promote fine sediment trapping during tidal and river flow, maintaining the balance between soil elevation and relative sea level rise on coastline stability and land building. Mike Island, located within Wax Lake Delta, Louisiana, USA, is part of a deltaic system created by a man-made freshwater diversion (1941) and one of few coastal areas where land is expanding in coastal Louisiana as result of pulsing river …

Fractal Shapes Generated By Iterated Function Systems, Mary Catherine Mckinley

LSU Master's Theses

This thesis explores the construction of shapes and, in particular, fractal-type shapes as fixed points of contractive iterated function systems as discussed in Michael Barnsley's 1988 book ``Fractals Everywhere." The purpose of the thesis is to serve as a resource for an undergraduate-level introduction to the beauty and core ideas of fractal geometry, especially with regard to visualizations of basic concepts and algorithms.