Physical Sciences and Mathematics Commons^™

Optics Design And Fabrication For A Lung Interferometry-Radiography System, Rachael Lyn Blair

LSU Master's Theses

Purpose: High prevalence of lung diseases leads to many people worldwide needing spirometry and imaging testing. The typical imaging done uses chest radiography and/or low-dose CT. Lung tissue is difficult to visualize, making them substandard for monitoring lung disease progression. An improvement on these systems is x-ray interferometry which produces additional images that provide better visualization of changes in the lung tissue. The set-up of x-ray interferometry builds upon other imaging systems in that it includes diffraction gratings.

Materials: This thesis focused on implementing the fabrication processes to create diffraction gratings for a lung imager prototype that is currently under …

Interactive Effects Of The Partial Pressure Of Co2, Temperature, And Nutrient-Limitation On The Physiology And Growth Of The Coccolithophore E. Huxleyi Grown On A 12:12 L:D Cycle Of Illumination, James Bradley

LSU Master's Theses

I studied the interactive effects of pCO2, temperature, and nutrient limitation on the growth and physiology of the marine coccolithophore, Emiliania huxleyi. This was done to look at the effect of climate change factors on the widespread and abundant calcifying marine organism as a predictor of what the future has to hold. The strain of E. huxleyi (PnB 272 B10) was grown on a 12:12 L:D cycle of illumination and exposed to either high or low pCO2 under nutrient-replete or nitrate-limited conditions across a temperature range of 10–28C. I examined the direct and interactive effects of temperature, pCO2, and nutrient …

Gulf Sturgeon Mesohabitat Use And Movement In The Lower Pearl River Louisiana-Mississippi, Amanda Popovich

LSU Master's Theses

After spring migrations to natal rivers Gulf Sturgeon Acipenser oxyrinchus desotoi reside in freshwater holding areas prior to fall emigrations to nearby estuaries. Limited published information on the physical habitat characteristics of these holding areas is available, especially for juvenile fish in the western portion of the Gulf Sturgeon’s distribution. To further investigate freshwater occupancy and movement patterns, 32 acoustic receivers were deployed from late April to October of 2021 and 2022 in 1600-m reaches distributed throughout the lower Pearl River, Louisiana-Mississippi, the westernmost river within their distribution. Generalized linear mixed models and multi-state models were used to determine what …

Review Of Structural Color In The Genus Chrysochroa Dejean, 1833 (Coleoptera: Buprestidae), Able Chow

LSU Master's Theses

The jewel beetles, (Coleoptera: Buprestidae Leach, 1815), is the eighth most speciose coleopteran family, with the majority of its members possessing diverse bright, saturated structural coloration of multilayer origin. This study focuses on the genus Chrysochroa Dejean, 1833, which includes some of the most brilliantly and charismatically colored buprestid species. While members of Chrysochroa are prised by entomologists amateurs and professional and are well-represented in museum collections, the evolution and ecology of their structural color remain underexplored. Twenty-eight select taxa including exemplars from all 13 subgenera of Chrysochroa were investigated to provide an overview of the objective optical properties and …

Wetland Soil Development Along Salinity And Hydrogeomorphic Gradients In Active And Inactive Deltaic Basins Of Coastal Louisiana, Amanda Fontenot

LSU Master's Theses

Coastal wetlands provide an abundance of ecosystem services that benefit society, such as essential habitat for commercial species, storm protection, nutrient cycling, and carbon storage. Louisiana faces rapid rates of relative sea level rise (natural subsidence and eustatic sea levels) that threaten wetland survival, which are amplified by a reduction of riverine sediment input. An important determining factor of marsh survival is the formation of wetland platform elevation, known as vertical accretion, which is determined by several processes including sediment deposition & erosion, below ground biomass (BGB) productivity, decomposition of organic matter, shallow & deep subsidence, and soil compaction. Feldspar …

Breeding Ecology Of Mottled Ducks In Southwestern Louisiana, Elizabeth Sophia Bonczek

LSU Doctoral Dissertations

Mottled ducks are a resident species found in the southern United States that rely on coastal marsh and associated habitat to fulfill the needs of the entirety of their annual cycle. Population monitoring has revealed declines in western Gulf Coast (WGC) mottled ducks since 2008. Mottled duck populations are influenced by survival and recruitment, and changes in these factors may contribute to population declines. The overarching goal of this project was to identify the mechanisms potentially limiting WGC mottled ducks.

I captured adult female mottled ducks during molt on Rockefeller Wildlife Refuge and adjacent lands in southwestern Louisiana from 2017–2019. …

A New Insight Into Fungal Cell Wall Architecture By Functional Genomics And Solid-State Nmr Along With Recent Advancements In Dynamic Nuclear Polarization For Analyzing Biomolecules, Arnab Chakraborty

LSU Master's Theses

This dissertation summarizes the findings related to the way by which supramolecular architecture of fungal cell wall changes with genetic mutation, dispensing genes responsible for biosynthesis of cell wall polysaccharides. This is necessary because without perfect picture of how supramolecular assembly changes with genetic mutation it is hard to assess new anti-fungal targets. Alongside this we have highlighted how recent advancement into Dynamic Nuclear Polarization (DNP) methods improved characterization of biomolecules both in case of labeled and unlabeled samples.

First study utilized Solid-state NMR (SSNMR) which is a non-destructive technique hence enabled us for the first time to deduce how …

Observing Reactive Events At The Aqueous Graphene Oxide Interface Using Deep Neural Network Potentials, Lukas Kim

Honors Theses

No abstract provided.

Synthesis Of Thiol-Acrylate Hydrogels For 3d Cell Culture And Microfluidic Applications, Anowar Hossain Khan

LSU Doctoral Dissertations

Globally cell culture is an $18.98 billion industry as of 2020, with an 11.6 percent annual growth rate. Drug discovery has an estimated worth of $69.8 billion in 2020 and is predicted to grow to $110.4 billion by 2025. Three-dimensional (3D) cell culture of cancer cells is one of the rapidly growing felids since it better recapitulates in vivo conditions compared to two-dimensional (2D) models. However, it is challenging to grow 3D tumor spheroids outside the body, and some of the existing technology can generate these spheroids outside the human body but poorly mimic in vivo tumor models. Therefore, there …

Regional Expansion And Evaluation Of Potential Chemical Control For Invasive Apple Snails (Pomacea Maculata) In Southwest Louisiana, Julian M. Lucero

LSU Master's Theses

The integration of monitoring and chemical control is an efficient strategy for managing invasive apple snails, Pomacea maculata, in the rice (Oryza sativa L.) and crawfish systems of southwest Louisiana. However, their current distribution, expansion rates, and susceptibility to chemical control methods in this area are not well known. This study evaluated the expansion of P. maculata in southwest Louisiana and assessed potential chemical control for P. maculata among toxicity assays using various application rates. The effects of potential chemical control were also assessed on a non-target species, the red swamp crawfish (Procambarus clarkii). P. maculata …

Blue Carbon In South Florida's Mangroves: The Role Of Large Roots And Necromass, Zoë I. Shribman

LSU Master's Theses

Blue carbon sequestration and storage in mangroves largely result from belowground biomass allocation in response to flooded anaerobic soil conditions and nutrient availability. Biomass allocation to belowground roots is a major driver of mangrove soil formation and organic matter accumulation leading to blue carbon storage potential. Belowground biomass sampling in mangroves is labor intensive, limiting data availability on biomass stocks, particularly for large roots (>20 mm diameter) and necromass (dead roots). The mangrove nutrient model (NUMAN) uses mostly literature values to parameterize a soil cohort approach to simulate depth distribution of root mass and organic carbon concentration. We evaluated …

Palynology And Paleoclimatology Of The Chicxulub Impact Crater In The Early Paleogene, Vann Smith

LSU Doctoral Dissertations

At the end of the Cretaceous Period, a large bolide impacted the Earth and formed the Chicxulub impact crater in the Yucatán Peninsula, Mexico. In 2016, International Ocean Discovery Program (IODP) Expedition 364 Site M0077 drilled into the buried peak ring of the crater, recovering a marine Paleocene to early Eocene post-impact section deposited on top of the impact breccia. Palynological analysis of 195 samples from the post-impact section has yielded the first pre-Holocene vegetational record from inside the Chicxulub impact crater and the first palynological record of the recovery of life following the end-Cretaceous mass extinction from inside the …

Phragmites Australis Dieback In The Mississippi River Delta: Chemical Profiles Of Soil Types And Restoration Potential, Herie Lee

LSU Master's Theses

Since 2016, there has been widespread dieback of P. australis in the Lower Mississippi River Delta (hereafter referred to as Lower MRD, which is defined as the Birds Foot Delta) with relatively little to no signs of recovery. The cause of the current dieback is not fully understood. This thesis explores P. australis with emphasis on chemical profile characterization of different soil types and its effects on plant growth and the potential for restoration in the Lower MRD.

In chapter 2, I characterized the chemical profiles of soils collected from healthy and dieback stands of Phragmites, and from newly …

Degumming Of Hemp Fibers Using Combined Microwave Energy And Deep Eutectic Solvent, Bulbul Ahmed

LSU Master's Theses

Hemp is considered as one of the sustainable agricultural fiber materials. Degumming or surface modification of hemp bast is needed to produce single fibers for ensuing textile and industrial applications. The traditional degumming process necessitates a high amount of alkali, which causes detrimental environmental pollution. This study offers a new method to degum hemp fibers with reduced use of harmful alkali and precious water resources. In this work, hemp bast fibers were degummed by using combined microwave energy and deep eutectic solvent (DES). The properties of hemp fibers manufactured by this method were investigated and compared with the traditional alkali …

Effect Of Forage Management Strategies And Land Use Change On Nitrogen Budget And Soil Health Parameters In Pasture Systems, Yili Meng

LSU Doctoral Dissertations

Pastures produce hay for livestock, and they conserve soil, water, and air resources. However, high nitrogen (N) fertilizer demands in pasture production have significant implication on greenhouse gas emission and environmental pollution. Appropriate forage management strategies can reduce environmental N loss and improve soil health, to enhance the long-term pasture productivity. Therefore, this study was carried out to investigate the effects of management strategies on N budgets and soil health parameters in subtropical pastures. Both field and laboratory experiments were conducted to evaluate the effects of N stabilizers including urease inhibitor and nitrification inhibitor on pasture yield, greenhouse gas emission, …

Incorporating Life Into Living Shorelines: Can Gulf Ribbed Mussels Reduce Shoreline Erosion And Enhance Restoration Practices?, Jordan Logarbo

LSU Master's Theses

The gulf ribbed mussel (Geukensia granosissima) exists throughout the Gulf of Mexico and influences biotic and abiotic environmental attributes as an ecosystem engineer. Ribbed mussels are an important component of marsh ecosystems providing services including filtering particulate matter, depositing and transforming nutrients in the system, increasing soil strength via byssal threads and providing structure via their shells.

The spatial distribution of mussels along the marsh edge of Sister Lake, LA was investigated via a broad survey of 150 sites, in relation to elevation, exposure and vegetation percent cover. This survey was followed by a second survey at a …

Mosquito Distribution And Stoichiometric Analysis Between Open And Closed Canopies In New Orleans Cemeteries, Rachel Rogers

LSU Master's Theses

Cemetery vases represent an important container habitat for mosquito larvae. Some species, like, Aedes albopictus and Aedes aegypti, prefer container habitats, whereas others, like Culex quinquefasciatus, will opportunistically use containers. In New Orleans, these three medically important vector species (Ae. albopictus Ae. aegypti, and Cx. quinquefasciatus) co-occur, despite a demonstrated competitive advantage of Ae. albopictus to the other two. Here we test the hypothesis that canopy cover from trees could be a mediating factor in driving mosquito assemblages in New Orleans, by influencing food sources, and the microclimate experienced by mosquito larvae. Samples from seven …

Plant Community Response To The Combined Effects Of Elevation, And Simulated Nutrient And Sediment Loading In Sagittaria Lancifolia-Dominated Wetlands, Donnie Day

LSU Master's Theses

Coastal wetlands are experiencing threats to their long-term sustainability brought about by the combined effects of relative sea-level rise and human modifications to hydrology, sediment delivery and nutrient loading. Restoration and management strategies can include adding sediment to the surface of deteriorating marshes to facilitate positive feedbacks among elevation, plant productivity, sediment trapping, and accretion; however, if delivered using nitrate-enriched river waters, belowground biomass and soil organic matter pools may be negatively affected, resulting in the acceleration of wetland loss. Overall, there is limited information on the combined effects of nutrient loading, sedimentation, and flooding dynamics in regulating feedbacks among …

Investigations Of The Structure And Protein-Protein Interactions Of Chlamydia Trachomatis Scc4, Thilini Oshadhi Senarath Ukwaththage

LSU Doctoral Dissertations

Chlamydia trachomatis (CT) is the most common, sexually transmitted bacterial disease (STD) in the world. In the developmental cycle of CT, specific chlamydia chaperone 4 (Scc4) is a unique protein with essential and multiple roles. Hence, Scc4 is significant as a virulence target for therapeutic approaches to treat chlamydial infections. A novel approach was discovered to purify tag free Scc4 by utilizing a 6X-histidine-tag on Scc1 in the co-expressed Scc4:Scc1 complex by capturing the complex on nickel-charged immobilized metal affinity chromatography resin, followed by dissociation of Scc4 with sarkosyl. Using triple resonance NMR experiments, backbone and sidechain resonances …

The Dna Cloud: Is It Alive?, Theodoros Bargiotas

LSU Doctoral Dissertations

In this analysis, I will firstly be presenting the current knowledge concerning the materiality of the internet based Cloud, which I will henceforth be referring to as simply the Cloud. For organisation purposes I have created two umbrella categories under which I place the ongoing research in the field. Scholars have been addressing the issue of Cloud materiality through broadly two prisms: sociological materiality and geopolitical materiality. The literature of course deals with the intricacies of the Cloud based on its present ferromagnetic storage functionality. However, developments in synthetic biology have caused private tech companies and University spin-offs to flirt …

The Life History And Population Dynamics Of Southern Flounder, Kenneth A. Erickson

LSU Master's Theses

Southern Flounder, Paralichthys lethostigma, are a coastal, estuarine-dependent flatfish species that inhabits the Southeastern US Atlantic Ocean and Gulf of Mexico. Throughout their range, Southern Flounder are exploited by both commercial and recreational fisheries. Recently, numerous sources have expressed concerns about Southern Flounder populations, with stock assessments indicating declines in spawning stock biomass and recruitment. To estimate life history traits needed for informed management, such as age, growth, and maturity, I collected 327 Southern Flounder from Louisiana and obtained 14,184 historical records from the Louisiana Department of Wildlife and Fisheries. Using a von Bertalanffy growth equation in a Bayesian …

Plant And Soil Responses To Sediment Deposition And Nutrient Enrichment In Healthy, Deteriorating, And Newly Created Coastal Marshes In Barataria Basin, Louisiana: Implications For Mississippi River Sediment Diversions, Gina N. Groseclose

LSU Master's Theses

To offset wetland loss in the Mississippi River Delta, sediment diversions that will re-introduce river water and sediment into wetlands are being planned for the lower Mississippi River. River diversions will also deliver high nutrient loads, which may reduce belowground plant productivity, reducing inputs of organic matter important for marsh accretion to keep pace with sea-level rise. However, belowground productivity responses to the combinatory effects of sediment and nutrients are unknown. To test the hypotheses that nutrient enrichment and sediment deposition interact to influence vegetation structure, belowground plant productivity and decomposition, and surface accretion, a field experiment was implemented in …

Reproductive Effort Of Montastraea Cavernosa Across Depth In The Context Of Both Climate Change Refugia And Emergent Disease, Jeanne Bloomberg

LSU Master's Theses

As coral populations on shallow reefs decline globally, mesophotic coral ecosystems (MCE) have been suggested as potential coral refugia in the face of climate changes, leading to the development of a comprehensive deep reef refugia hypothesis. The current study assesses the climate and disease refuge potential of MCEs in the U.S. Virgin Islands (USVI) for the gonochoric, broadcast-spawning species Montastraea cavernosa. Polyp, population, and total habitat fecundities were estimated across the species’ depth range, and changes to population oocyte production over time due to recent ecosystem disturbances were considered. The number of gonads producing oocytes in each polyp and oocyte …

Characterization Of Shallow Subsurface Hydrology In Large Fine-Grained Floodplains, Mary Grace Lemon

LSU Doctoral Dissertations

Floodplains are hydrologically dynamic, receiving water from overbank events, hyporheic flows, local precipitation, and regional groundwater sources. These sources are variously important contributors to the heterogeneous floodplain water pool that includes matrix water in soil micropores, mobile water in soil macropores, groundwater below the rooting zone, ephemeral to seasonal surface storage, and permanent surface water features such as oxbow lakes, sloughs, and other secondary channels. All sources may be ecologically relevant for floodplain vegetation, but the exact roles of each source in both controlling soil water and shallow groundwater recharge and in controlling floodplain water drainage are not well understood, …

Antimicrobial Strategies For Topical Applications, Kelsey Marie Lopez

LSU Doctoral Dissertations

Bacteria can thrive in diverse environments and are often harmless or beneficial. Bacteria in digestive tracts is one example of beneficial bacteria; however, bacteria can be harmful and when this type proliferates, it can cause infections within hosts. Bacterial infections are easily treated with antibiotics in most cases. However, bacteria are also capable of developing mutations which could cause them to become multi-drug resistant and eventually, “superbugs.” Therefore, the development of novel antimicrobial agents and materials capable of combating drug-resistant bacteria is necessary. Research presented in this dissertation focuses on different strategies for minimizing and preventing topical bacterial infections using …

Estimating The Onset And Extent Of Dieback Of Phragmites Australis Using The Normalized Difference Vegetation Index And Remotely Sensed Land Cover Classifications, Aimee M. Beaudette

LSU Master's Theses

Phragmites australis is cosmopolitan plant species with an invasive variety present throughout most of North America. In the Balize Delta, Louisiana, USA, P. australis plays an important role in combatting subsidence, maintaining navigation channels, and protecting interior fish and wildlife habitat from waves and storm surge. In 2016 a dieback of P. australis was reported by wetland managers, coinciding with the appearance of an invasive Asian scale insect (Nipponaclerda biwakoensis), though the specific cause is still unknown. Two previous efforts attempted to identify the onset of dieback conditions met with limited success. Using Landsat images from 1985 to …

Physical And Biological Factors Controlling The Fate Of Nitrate In A Louisiana Coastal Deltaic Floodplain, Alexandra Christensen

LSU Doctoral Dissertations

The Mississippi River Delta is threatened by a growing pressure to support large human populations in the United States both with food production, navigation systems, and urban development in the Mississippi River Basin. Nitrate-nitrogen load in the Mississippi River, up to 100 Tg N yr^-1 from agricultural and urban runoff, leads to phytoplankton blooms and hypoxia across the Louisiana continental shelf, creating dead zones of low dissolved oxygen threatening a significant commercial fishery. Along the coast and river corridors, floodplain ecosystems have the capacity to retain and remove nitrate. This dissertation explores the role of productive, actively growing coastal …

An Ecopath With Ecosim Analysis On Offshore Petroleum Platform Influences On Gulf Of Mexico Red Snapper, Valentin Gomez

LSU Master's Theses

Offshore oil and gas platforms have had a significant presence in the Gulf of Mexico since the 1950s. An important secondary function of these structures is that they provide artificial habitat to fisheries, most notably Red snapper. Policy changes intended to reduce the risk associated with aging infrastructure have reduced the number of standing platforms from 4044 to 1867 from 2001 to 2018. The effect this loss of habitat has on Red snapper was tested by creating three scenarios of platform changes and modeling the perturbation from 2005 to 2050. The simulation was accomplished using the ecological model Ecopath with …

Role Of Coastal Environmental Conditions During Austral Winter On Plankton Community Dynamics And The Occurrence Of Pseudo-Nitzschia Spp. And Domoic Acid In Inhambane Province, Mozambique, Holly Kelchner

LSU Master's Theses

Harmful algal blooms (HABs) are increasing globally in frequency, persistence, and geographic extent. HABs pose a threat to economic stability, and ecosystem and human health. To date no incidences of marine toxins produced by phytoplankton have been recorded in Mozambique, which may be due to the absence of a monitoring program and general awareness of the potential threat. This study is the first documentation of the occurrence of a neurotoxin, domoic acid (DA), produced by the diatom genus Pseudo-nitzschia spp. along the east coast of Africa. The coast of Inhambane Province is a biodiversity hotspot where year-round Rhincodon typus (whale …

Assessment Of Soil Protein And Refractory Soil Organic Matter Across Two Chronosequences Of Newly Developing Marshes In Coastal Louisiana, Usa, Stuart Alexander Mcclellan

LSU Doctoral Dissertations

The impacts of sea-level rise and hydrologic manipulation are threatening the stability of coastal marshes throughout the world, thereby increasing the potential for re-mineralization of soil organic matter (SOM) in these systems. Such threats have prompted marsh restoration efforts, particularly in coastal Louisiana, yet it is unclear how the slowly decomposing (refractory) and quickly decomposing (labile) fractions of SOM may be differentially affected by different approaches to marsh restoration. Additionally, otherwise labile compounds may accumulate in the soil via a range of protective mechanisms, including rapid burial and association with organic compounds that are thought to enhance soil aggregation, such …