Emergent Functional Behaviour Of Humic Substances Perceived As Complex Labile Aggregates Of Small Organic Molecules And Oligomers, Robert L. Cook

Faculty Publications

The structural organisation of humic substances (HS) has been a central question of earth sciences for several decades. The latest experimental results have led to the recognition of HS as complex mixtures of small molecules and oligomers. We investigate the correlation between the chemical composition of HS, perceived as labile aggregates, and the emergent functions. Computational modelling was used to help to understand the processes and mechanisms on the molecular scale that occur in different fractions of the HS, fulvic acids (FA) and humic acids (HA), as they interact with metal ions and organic pollutants. The importance of non-covalent interactions …

Avian Ecological Succession In The Amazon: A Long-Term Case Study Following Experimental Deforestation, Cameron L. Rutt, Vitek Jirinec

Faculty Publications

Approximately 20% of the Brazilian Amazon has now been deforested, and the Amazon is currently experiencing the highest rates of deforestation in a decade, leading to large-scale land-use changes. Roads have consistently been implicated as drivers of ongoing Amazon deforestation and may act as corridors to facilitate species invasions. Long-term data, however, are necessary to determine how ecological succession alters avian communities following deforestation and whether established roads lead to a constant influx of new species. We used data across nearly 40 years from a large-scale deforestation experiment in the central Amazon to examine the avian colonization process in a …

Abundance And Survival Of Microbial Aerosols In The Troposphere And Stratosphere, N. C. Bryan, B. C. Christner, T. G. Guzik, D. J. Granger, M. F. Stewart

Faculty Publications

Bioaerosol transport in the atmosphere disperses microbial species between continents, affects human and plant health, and may influence hydrologic cycling. However, there have been few quantitative observations of bioaerosols at altitudes more than a few kilometers above the surface. Lack of data on bioaerosol distributions in the atmosphere has impeded efforts to assess the aerial dissemination of microbes and their vertical extent in the biosphere. In this study, a helium balloon payload system was used to sample microbial cells and dust particles in air masses as high as 38 km above sea level over three locations in the southwestern United …

Dissolved Carbon Export And Co2 Outgassing From The Lower Mississippi River – Implications Of Future River Carbon Fluxes, J. H. Reiman, Y. Jun Xu

Faculty Publications

No abstract provided.

Lignin Chemistry Of Wetland Soil Profiles In Two Contrasting Basins Of The Louisiana Gulf Coast, Weiyang Bi, J. J. Wang, Syam K. Dodla, Lewis A. Gaston, Ronald D. Delaune

Faculty Publications

Recent studies indicate that loss of soil organic matter (SOM) from coastal wetlands can contribute to the hypoxia in the northern Gulf of Mexico along the Louisiana coast. In this study, coastal marsh soil profiles of two contrasting basins were investigated for lignin composition in order to assess organic matter source and degradation status under these different wetland formations. The Atchafalaya Basin is undergoing land building whereas the Barataria Basin is experiencing land loss. Lignin monomers were extracted using alkaline CuO oxidation followed by gas chromatography–mass spectrometry characterization. Marsh soil profiles from the Barataria Basin showed strong lignin storage with …

Is Iodine Deficiency Still A Problem In Sub-Saharan Africa?: A Review, Sanjoy Saha, Brenda A.Z. Abu, Yasaman Jamshidi-Naeini, Upasana Mukherjee, Makenzie Miller, Li Ling Peng, Wilna Oldewage-Theron

Faculty Publications

Iodine is an essential trace mineral, vital for its functions in many physiological processes in the human body. Both iodine deficiency (ID) and excess are associated with adverse health effects; ID and excess iodine intake have both been identified in sub-Saharan Africa (SSA). The review aims to (1) review the iodine status among populations in SSA until October 2018, and (2) identify populations at risk of excess or inadequate iodine intakes. A systematic search of relevant articles was carried out by a seven-member research team using PubMed, Science Direct and Scopus. A total of twenty-two articles was included for data …

Expected Genotype Quality And Diploidized Marker Data From Genotyping-By-Sequencing Of Urochloa Spp. Tetraploids, Filipe Inácio Matias, Karem Guimarães Xavier Meireles, Sheila Tiemi Nagamatsu, Sanzio Carvalho Lima Barrios, Cacilda Borges Do Valle, Marcelo Falsarella Carazzolle, Roberto Fritsche-Neto, Jeffrey B. Endelman

Faculty Publications

Although genotyping-by-sequencing (GBS) is a well-established marker technology in diploids, the development of best practices for tetraploid species is a topic of current research. We determined the theoretical relationship between read depth and the phred-scaled probability of genotype misclassification conditioned on the true genotype, which we call expected genotype quality (EGQ). If the GBS method has 0.5% allelic error, then 17 reads are needed to classify simplex tetraploids as heterozygous with 95% accuracy (EGQ = 13) vs. 61 reads to determine allele dosage. We developed an R script to convert tetraploid GBS data in variant call format (VCF) into diploidized …

Effect Of F1 And F2 Generations On Genetic Variability And Working Steps Of Doubled Haploid Production In Maize, Evellyn Giselly De Oliveira Couto, Mayara Neves Cury, Massaine Bandeira E Souza, Ítalo Stefanine Correia Granato, Miriam Suzane Vidotti, Deoclécio Domingos Garbuglio, José Crossa, Juan Burgueño, Roberto Fritsche-Neto

Faculty Publications

For doubled haploid (DH) production in maize, F1 generation has been the most frequently used for haploid induction due to facility in the process. However, using F2 generation would be a good alternative to increase genetic variability owing to the additional recombination in meiosis. Our goals were to compare the effect of F1 and F2 generations on DH production in tropical germplasm, evaluating the R1-navajo expression in seeds, the working steps of the methodology, and the genetic variability of the DH lines obtained. Sources germplasm in F1 and F2 generations were crossed with the tropicalized haploid inducer LI-ESALQ. After harvest, …

Grids & Datums, Clifford J. Mugnier

Faculty Publications

No abstract provided.

Late Pleistocene Site Formation And Paleoclimate At Lapa Do Picareiro, Portugal, Michael M. Benedetti, Jonathan A. Haws, Nuno F. Bicho, Lukas Friedl, Brooks B. Ellwood

Faculty Publications

© 2019 Wiley Periodicals, Inc. The cave site of Lapa do Picareiro, Portugal contains a deep (~10 m) sedimentary sequence representing much of the Middle and Upper Paleolithic, with abundant animal bones, lithic/bone/shell artifacts, and charcoal/ash in hearths. A deposition model based on 49 radiocarbon ages demonstrates average sedimentation rates of 0.1–0.3 mm a −1 between 9 and 45 ka. Extrapolation suggests an age at the base of the excavation of 65–78 ka. The cave sediments are primarily limestone éboulis derived from roof spalling, and muddy fine sediment derived from weathered soil infiltrating through bedrock joints and crevices. Bone preservation …

Undrained Cylindrical Cavity Expansion In Anisotropic Critical State Soils, Shengli Chen, Kai Liu, Jorge Castro, Nallathamby Sivasithamparam

Faculty Publications

No abstract provided.

Scheduling Optimization Of Parallel Linear Algebra Algorithms Using Supervised Learning, Gabriel Laberge, Shahrzad Shirzad, Patrick Diehl, Hartmut Kaiser, Serge Prudhomme, Adrian S. Lemoine

Faculty Publications

Linear algebra algorithms are used widely in a variety of domains, e.g machine learning, numerical physics and video games graphics. For all these applications, loop-level parallelism is required to achieve high performance. However, finding the optimal way to schedule the workload between threads is a non-trivial problem because it depends on the structure of the algorithm being parallelized and the hardware the executable is run on. In the realm of Asynchronous Many Task runtime systems, a key aspect of the scheduling problem is predicting the proper chunk-size, where the chunk-size is defined as the number of iterations of a for-loop …

Exploring Planetary Surfaces With Remote Sensing, Donald R. Hood

LSU Doctoral Dissertations

Aside from Earth, Mars is the most well-explored planetary body in our solar system. Much has been learned about its geologic past including a history of volcanism, ice ages, and potentially long-lasting liquid water. Much of this knowledge of Mars comes from remote observations of the surface and atmosphere from Mars-orbiting satellites. Such remote observations remain the only way to examine the entirety of Mars’ surface as rovers and landers can only examine small areas. The chapters of this work cover three projects that explore the surface of Mars through a variety of remote sensing methods.

In chapter 1, Gamma-ray …

Identification Of Quantitative Trait Loci (Qtls) For Resistance To Fusarium Head Blight (Fhb) In Wheat Variety Ags 2060 And Evaluation Of The Effect Of Fhb1 Resistance Gene On Fhb Reaction In A Louisiana Wheat Breeding Population, Alejandro Castro Aviles

LSU Doctoral Dissertations

Fusarium head blight (FHB), caused by the fungus Fusarium spp., is a disease that attacks several grass species, including wheat. Wheat variety AGS 2060 has remained moderately susceptible to FHB and is regularly found in pedigrees of resistant breeding lines. Quantitative trait loci (QTL) mapping was conducted to find sources of resistance to FHB in AGS 2060. A 90K SNP chip was used to genotype a double haploid mapping population produced from a cross between wheat varieties AGS 2060 and AGS 2035. There were highly significant differences between lines in the population for Fusarium damaged kernels (FDK) rating and deoxynivalenol …

The Power Of Wording: An Evaluation Of Framing Effects, Chelsea Romph

Honors Capstones

No abstract provided.

The Ability Of Β-Hairpin Peptides To Function As Degradation-Resistant, Cell-Penetrating Peptides And Their Potential As Proteolysis Targeted Chimeras, Jeffery C. Anderson

Honors Capstones

No abstract provided.

Review Of Naturally Occurring Ammonia In Groundwater And Its Effect On Using Chloramines For Drinking Water Disinfection In Louisiana, Athena Lindsay

Honors Capstones

No abstract provided.

Cellular And Viral Determinants Of Hsv-1 Entry And Transport, Farhana Musarrat

LSU Doctoral Dissertations

Previously, it was shown that the deletion of 38 amino acids from the N terminal end of glycoprotein K (gK) prevents the Herpes Simplex virus Type-1 (HSV-1McKrae ∆gK31-68) from entering into the axons of neurons. Herein, we showed for the first time that this modification in gK disrupts the ability of the virus to carry out a fusion of the viral envelope with the cellular plasma membrane and forces the virus to enter via endocytosis in epithelial cells and neuronal cell bodies. We showed that HSV-1 McKrae infection triggers cellular calcium signaling, Akt activation, and flipping of Akt to the …

The Functional, Ecological, And Evolutionary Morphology Of Sea Lampreys (Petromyzon Marinus), Bradley Morgan Wood

LSU Doctoral Dissertations

Lampreys (Petromyzontiformes) are jawless vertebrates with an evolutionary history lasting at least 360 million years and are often used in comparisons with jawed vertebrates because some of their morphological aspects, such as the segmented trunk musculature with curved myosepta and a non-mineralized skeleton fibrous skeleton, are thought to resemble the condition of early vertebrates before the evolution of jaws. Although earlier authors studied the morphology of the skeleto-muscular system of the trunk of lampreys, their studies are not detailed and complete enough to allow a functional and biomechanical analysis that is needed as a basis for modeling the mechanics of …

Neogene Chemical Weathering And Provenance Records Of The Western Himalaya Preserved In The Arabian Sea, Peng Zhou

LSU Doctoral Dissertations

Some tectonic models for the Himalaya emphasize the importance of surface processes in controlling the structural evolution. To investigate this tectonic–climatic interactions, and the weathering and erosion of the western Himalaya, International Ocean Discovery Program (IODP) Expedition 355 drilled two sites (site U1456 and U1457) in Laxmi Basin, which located in the Eastern Arabian Sea. In my research project, I plan to use a series of geochemical and geochronological methods on the sediment samples from the cores of these two sites, and sediments from an industrial borehole Indus Marine A-1, which near the Indus river mouth, to reconstruct a climatic …

Prevalence And Control Of Salmonella Spp. And Sanitary Indicator Microorganisms In Wild Caught And Farm Raised Catfish (Ictalurus Punctatus), Bilan Costley Jessie

LSU Doctoral Dissertations

Catfish inspections have transitioned from the U.S. Food and Drug Administration (FDA) to the United States Department of Agriculture (USDA). The USDA Food Safety and Inspection Service (FSIS) and Food Emergency Response Network (FERN) consider it important to assess the food safety risk associated with consuming catfish in the United States. Surveillance of farm-raised and wild-caught catfish for pathogens is relevant as a public safety protocol. The purpose of this study was to detect the prevalence of Salmonella spp., identify and examine isolates for antibiotic resistance to clinical treatments, evaluate the effectiveness of antimicrobial chemical treatments against Salmonella enterica, and …

Investigations Of Thermal Treatment Of Softwood Kraft Lignin Under Fractional And Ablative Pyrolytic Conditions, Dideolu J. Daniel

LSU Master's Theses

Lignin is second to cellulose in abundance among polymers in nature. Research studies on the development of new products and material combinations in which lignin degradation/conversion products are involved are still in their infancy, because fundamental knowledge about its structure, reactivity, and material and polymer behavior, is still lacking.

The objective of this research study was to investigate the complex thermal deconstruction and mechanistic behavior of a type of technical lignin, known as Kraft lignin, under depolymerization and to develop operating conditions for parameters influencing resulting product yields and operation of pyrolysis reactors.

Softwood Kraft lignin (s-KL) and methanol-fractionated (ex-KL) …

Influence Of The Annual Flood Pulse Of The Atchafalaya River And Updates On The Ecology Of Floodplain Aquatic And Semi-Aquatic Hemiptera And Their Associates, Patricia Ls Wooden

LSU Master's Theses

Understanding the biodiversity of insects in an area provides key insights into the health and uniqueness of an ecosystem. Here we increase the breadth of knowledge of Louisiana aquatic Hemiptera through field and natural history collection research. The Atchafalaya River floodplain is variably inundated throughout the course of the year, peaking with the spring flood pulse, resulting in spatiotemporally dynamic habitats for aquatic organisms. Buffalo Cove Water Management Unit (BC) is within the river system, whereas Lake Fausse Pointe (LFP) has been leveed from the influence of the river for over 50 years. We collected aquatic macroinvertebrates with quatrefoil light …

Evaluating Feline Release Criteria Following Iodine-131 Therapy For Hyperthyroidism, Anthony Davila

LSU Master's Theses

Hyperthyroidism is a very common endocrine disorder in both humans and cats. Radioactive iodine ablation therapy is considered the gold standard; however, the patient becomes a radiation source and poses a potential radiological risk to others. The regulations governing when the patient can be released differ between human medicine and veterinary medicine. A human patient can receive up to 33 mCi of I-131 and be discharged the same day; yet a feline patient can receive a dose as low as 2 mCi and require multiple days of hospitalization. This discrepancy has not been satisfactorily addressed; and overly restrictive release criteria …

Coupled Pore-To-Continuum Multiscale Modeling Of Dynamic Particle Filtration Processes In Porous Media, John Rayner Blears

LSU Doctoral Dissertations

Modeling particle transport and retention in porous media is important in fields such as hydrocarbon extraction, groundwater filtration, and membrane separation. While the continuum-scale (>1 m) is usually of practical interest, pore-scale (1-100 μm) dynamics govern the transport and retention of particles. Therefore, accurate modeling of continuum-scale behavior requires an effective incorporation of pore-scale dynamics. Due to current computational limits however, the large spatial and temporal discrepancies of these scales prohibit modeling an entire continuum-scale system as a single pore-scale model. Even if a pore-scale model could incorporate every pore contained in a continuum-scale system, an upscaling scheme that …

Past East Asian Monsoon Evolution Controlled By Paleogeography, Not Co2, Alex Farnsworth, Daniel J. Lunt, Stuart A. Robinson, Paul J. Valdes, William H.G. Roberts, Peter D. Clift, Paul Markwick, Tao Su, Neil Wrobel, Fran Bragg, Sarah Jane Kelland, Richard D. Pancost

Faculty Publications

Copyright © 2019 The Authors, The East Asian monsoon plays an integral role in human society, yet its geological history and controlling processes are poorly understood. Using a general circulation model and geological data, we explore the drivers controlling the evolution of the monsoon system over the past 150 million years. In contrast to previous work, we find that the monsoon is controlled primarily by changes in paleogeography, with little influence from atmospheric CO2. We associate increased precipitation since the Late Cretaceous with the gradual uplift of the Himalayan-Tibetan region, transitioning from an ITCZ-dominated monsoon to a sea breeze–dominated monsoon. …

Factors Influencing Retirement Decision Making For Louisiana State Government Employees, Osama A. Amous

LSU Doctoral Dissertations

ABSTRACT

Public pension members continually face factors affecting their decision to retire in the changing American society. Workers are living longer and need more medical care with better retirement benefits. For Louisiana public employees specifically, no prior studies have examined the factors affecting workers’ decision to retire nor evaluated the factors impacting workers’ decision.

This multiphase study aimed to identify factors and evaluate the decision-making process that enables Louisianans to retire happily and satisfied with a guaranteed income, and to examine millennials’ decision-making process. In the initial phase, ten active and retired male and female participants answered questions in-person, leading …

Characterizing The Roles Of Nuclear Proteins Dbc1, G9a, And Glp In Adipocyte Function And Metabolic Health, Ashley Ann Able

LSU Doctoral Dissertations

Obesity is a metabolic disorder characterized by excess energy storage in adipose tissue and it increases the risk for Type 2 diabetes. Impaired or altered adipocyte function during obesity can contribute to metabolic dysfunction. DBC1 (deleted in breast cancer 1) and EHMTs 1 and 2 (euchromatic histone lysine methyltransferases 1 and 2) have been shown to have a role in fat cell development and function. DBC1 is typically localized in the nucleus and can regulate a variety of epigenetic modifiers, transcription factors, and nuclear receptors. EHMTs 1 and 2, also known respectively as GLP and G9a, were initially classified as …

Unidirectional And Nonreciprocal Nanophotonic Devices Based On Graphene And Magneto-Optical Materials, Vahid Foroughi Nezhad

LSU Doctoral Dissertations

In this dissertation, we first introduce compact tunable spatial mode converters for graphene parallel plate (GPP) waveguides. The converters are reciprocal and based on spatial modulation of graphene’s conductivity. The wavelength of operation of the mode converters is tunable in the mid-infrared wavelength range by adjusting the chemical potential of a strip on one of the graphene layers of the GPP waveguides. We also introduce optical diodes for GPP waveguides based on a spatial mode converter and a coupler, which consists of a single layer of graphene placed in the middle between the two plates of two GPP waveguides. \par …

Vanadium-Based Nanomaterials For Improved Zn Ion Storage, Jianwei Lai

LSU Master's Theses

Rechargeable aqueous zinc-ion batteries (ZIBs) have been intensively studied as novel promising large-scale energy storage systems recently, owing to their advantages of high abundance, cost effectiveness, and high safety. However, the development of suitable cathode materials with superior performance are severely hampered by the sluggish kinetics of Zn²⁺ with divalent charge in the host structure.

Our Work demonstrates boosting the electrochemical performances of nanostructured cathode materials for aqueous ZIBs. The first project is focused on the interlayer-expanded V₆O₁₃∙nH₂O nanosheets as promising cathodes. Benefiting from the synthetic merits of its favorable architecture and expanded …