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Fracture Diodes: Directional Asymmetry Of Fracture Toughness, N. R. Brodnik, S. Brach, C. M. Long, G. Ravichandran, B. Bourdin, K. T. Faber, K. Bhattacharya Jan 2021

Fracture Diodes: Directional Asymmetry Of Fracture Toughness, N. R. Brodnik, S. Brach, C. M. Long, G. Ravichandran, B. Bourdin, K. T. Faber, K. Bhattacharya

Faculty Publications

Toughness describes the ability of a material to resist fracture or crack propagation. It is demonstrated here that fracture toughness of a material can be asymmetric, i.e., the resistance of amedium to a crack propagating from right to left can be significantly different from that to a crack propagating from left to right. Such asymmetry is unknown in natural materials, but we show that it can be built into artificial materials through the proper control of microstructure. This paves the way for control of crack paths and direction, where fracture - when unavoidable - can be guidedthrough predesigned paths to …

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Rapid Spectral Variability Of A Giant Flare From A Magnetar In Ngc 253, O. J. Roberts, P. Veres, M. G. Baring, M. S. Briggs, C. Kouveliotou, E. Bissaldi, G. Younes, S. I. Chastain, J. J. Delaunay, D. Huppenkothen, A. Tohuvavohu, P. N. Bhat, E. Göğüş, A. J. Van Der Horst, J. A. Kennea, D. Kocevski, J. D. Linford, S. Guiriec, R. Hamburg, C. A. Wilson-Hodge, E. Burns Jan 2021

Rapid Spectral Variability Of A Giant Flare From A Magnetar In Ngc 253, O. J. Roberts, P. Veres, M. G. Baring, M. S. Briggs, C. Kouveliotou, E. Bissaldi, G. Younes, S. I. Chastain, J. J. Delaunay, D. Huppenkothen, A. Tohuvavohu, P. N. Bhat, E. Göğüş, A. J. Van Der Horst, J. A. Kennea, D. Kocevski, J. D. Linford, S. Guiriec, R. Hamburg, C. A. Wilson-Hodge, E. Burns

Faculty Publications

Magnetars are neutron stars with extremely strong magnetic fields (1013 to 1015 gauss)1,2, which episodically emit X-ray bursts approximately 100 milliseconds long and with energies of 1040 to 1041 erg. Occasionally, they also produce extremely bright and energetic giant flares, which begin with a short (roughly 0.2 seconds), intense flash, followed by fainter, longer-lasting emission that is modulated by the spin period of the magnetar3,4 (typically 2 to 12 seconds). Over the past 40 years, only three such flares have been observed in our local group of galaxies3–6, and in all cases the extreme intensity of the flares caused the …

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Ceo Political Ideology: Implications For Firm Innovation, Samira Fallah Jan 2021

Ceo Political Ideology: Implications For Firm Innovation, Samira Fallah

LSU Doctoral Dissertations

In this dissertation, I examine the influence of CEO political ideology on firm’s innovation strategy and outcomes. In my theorizing, I draw on upper-echelons theory that underscores the role of executives’ personal orientations on their decisions as well as the scholarship in political psychology that demonstrates the different values and psychological needs of liberals and conservatives. Given liberals’ lower need to manage uncertainty and their openness to new experiences, I propose that a firm with a more liberal CEO is likely to develop more innovations, pursue exploratory innovations and develop innovations with extreme quality (high and low). I also build …

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A Microscale Approach To Investigate Breast Cancer Cellular Communication And Migration, Sharif Mohammad Mizanur Rahman Jan 2021

A Microscale Approach To Investigate Breast Cancer Cellular Communication And Migration, Sharif Mohammad Mizanur Rahman

LSU Doctoral Dissertations

Metastatic breast cancer significantly decreases patient survival, with the majority of deaths caused by secondary metastasis. Cancer metastasis is a multi-step process that starts with the detachment of a cancer cell from the primary tumor and ends with establishing a secondary tumor at a distal location. This work's focus was to use an interdisciplinary microscale approach to study how cancer cells respond to neighboring cells and how they migrate in response to chemical gradients. Two distinct devices, a microfluidic device, and a 3D-printed plate insert, were developed to perform co-culture studies to elucidate the impact of ASCs on cancer cell …

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Corrosion Performance Of Additively Manufactured Alloys And Hot Corrosion, Ali Hemmasian Ettefagh Jan 2021

Corrosion Performance Of Additively Manufactured Alloys And Hot Corrosion, Ali Hemmasian Ettefagh

LSU Doctoral Dissertations

Additive manufacturing (AM) has gained attention in recent years due to its unique properties in the fabrication of complex parts. Same as any other new topics, in some areas, there is still a lack of enough knowledge and there is the need for further investigations to enable the applications of AM parts widely in industries. ‎Chapter 2, and ‎Chapter 5 to ‎Chapter 8 of this report are focused on the corrosion properties of the parts and coatings fabricated using the laser powder bed fusion based AM method or laser surface processing method, including a comprehensive review. Laser powder bed fusion …

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A Burkholderia Thailandensis Deda Family Membrane Protein Is Required For Proton Motive Force Dependent Lipid A Modification, Pradip R. Panta, William T. Doerrler Jan 2021

A Burkholderia Thailandensis Deda Family Membrane Protein Is Required For Proton Motive Force Dependent Lipid A Modification, Pradip R. Panta, William T. Doerrler

Faculty Publications

The DedA family is a conserved membrane protein family found in most organisms. A Burkholderia thailandensis DedA family protein, named DbcA, is required for high-level colistin (polymyxin E) resistance, but the mechanism awaits elucidation. Modification of lipopolysaccharide lipid A with the cationic sugar aminoarabinose (Ara4N) is required for colistin resistance and is dependent upon protonmotive force (PMF) dependent transporters. B. thailandensis ΔdbcA lipid A contains only small amounts of Ara4N, likely leading to colistin sensitivity. Two B. thailandensis operons are required for lipid A modification with Ara4N, one needed for biosynthesis of undecaprenyl-P-Ara4N and one for transport of the lipid …

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Stem Cell Factor In Combination With Granulocyte Colony-Stimulating Factor Protects The Brain From Capillary Thrombosis-Induced Ischemic Neuron Loss In A Mouse Model Of Cadasil, Suning Ping, Xuecheng Qiu, Maria E. Gonzalez-Toledo, Xiaoyun Liu, Li Ru Zhao Jan 2021

Stem Cell Factor In Combination With Granulocyte Colony-Stimulating Factor Protects The Brain From Capillary Thrombosis-Induced Ischemic Neuron Loss In A Mouse Model Of Cadasil, Suning Ping, Xuecheng Qiu, Maria E. Gonzalez-Toledo, Xiaoyun Liu, Li Ru Zhao

Faculty Publications

Cerebral autosomal dominant arteriopathy with subcortical infarct and leukoencephalopathy (CADASIL) is a Notch3 mutation-induced cerebral small vessel disease, leading to recurrent ischemic stroke and vascular dementia. There is currently no treatment that can stop or delay CADASIL progression. We have demonstrated the efficacy of treatment with combined stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF) (SCF+G-CSF) in reducing cerebral small vessel thrombosis in a TgNotch3R90C mouse model of CADASIL. However, it remains unknown whether SCF+G-CSF treatment protects neurons from microvascular thrombosis-induced ischemic damage. Using bone marrow transplantation to track thrombosis, we observed that capillary thrombosis was widely distributed in …

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Resistance To Aflatoxin Accumulation In Maize Mediated By Host-Induced Gene Silencing Of Aspergillus Flavus Alkaline Protease And O-Methyltransferase-A Genes, Olanike Omotola Omolehin Jan 2021

Resistance To Aflatoxin Accumulation In Maize Mediated By Host-Induced Gene Silencing Of Aspergillus Flavus Alkaline Protease And O-Methyltransferase-A Genes, Olanike Omotola Omolehin

LSU Doctoral Dissertations

Aspergillus flavus is a soil-borne fungal pathogen that infects maize and produces aflatoxins. In the current study, portions of the alkaline protease (alk) and the O-methyl transferase (omtA) genes, which are key in A. flavus virulence and aflatoxin biosynthesis, respectively, were targeted for suppression through an RNAi (RNA interference) approach known as Host-Induced Gene Silencing (HIGS). Separate RNAi vectors were designed to carry regions of the alk and omtA gene fragments (Alk-RNAi and OmtA-RNAi) and introduced into B104 maize zygotic embryos. Eight and six transformation events were positive for the alk and omtA transgene, respectively. …

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Arthropods Are Not Declining But Are Responsive To Disturbance In The Luquillo Experimental Forest, Puerto Rico, Timothy D. Schowalter, Manoj Pandey, Steven J. Presley, Michael R. Willig, Jess K. Zimmerman Jan 2021

Arthropods Are Not Declining But Are Responsive To Disturbance In The Luquillo Experimental Forest, Puerto Rico, Timothy D. Schowalter, Manoj Pandey, Steven J. Presley, Michael R. Willig, Jess K. Zimmerman

Faculty Publications

A number of recent studies have documented long-term declines in abundances of important arthropod groups, primarily in Europe and North America. These declines are generally attributed to habitat loss, but a recent study [B.C. Lister, A. Garcia, Proc. Natl. Acad. Sci. USA 115, E10397-E10406 (2018)] from the Luquillo Experimental Forest (LEF) in Puerto Rico attributed declines to global warming. We analyze arthropod data from the LEF to evaluate long-term trends within the context of hurricane-induced disturbance, secondary succession, and temporal variation in temperature. Our analyses demonstrate that responses to hurricane-induced disturbance and ensuing succession were the primary factors that affected …

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A Conjecture On The Irregularity Function For Local Geometric Langlands Parameters And The Formal Frenkel-Gross Connection, Andrew Alaniz Jan 2021

A Conjecture On The Irregularity Function For Local Geometric Langlands Parameters And The Formal Frenkel-Gross Connection, Andrew Alaniz

LSU Doctoral Dissertations

For a simple complex algebraic group $G$, M. Kamgarpour and D. Sage have shown that the adjoint irregularity of an irregular singular flat $G$-bundle on the formal punctured disc is bounded from below by the rank of $G$, moreover the rank is realized by the formal Frenkel-Gross connection. This is a geometric analog of a conjecture of Gross and Reeder on the swan conductor of arithmetic local Langlands parameters. In this work, we explore an interesting combinatorial problem which arises when trying to consider the minimal value of the irregularity function with respect to an arbitrary representation of $G$.

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Evaluating Us Consumers' Perception Of Foods Made With Cricket Powder, Ryan Paul Ardoin Jan 2021

Evaluating Us Consumers' Perception Of Foods Made With Cricket Powder, Ryan Paul Ardoin

LSU Doctoral Dissertations

Expanding the consumption of edible insects has been proposed as a strategy for global food security due to their sustainability of production and high nutritional value. In the U.S.A., the idea of eating insects is generally unappealing. This research took a methodical approach to understanding U.S. consumers perceptions of insects as food- specifically, products made with cricket powder. Recent consumer-oriented entomophagy research (2015-2020) was reviewed to consolidate understanding of Westerners’ perceptions of edible insects and to evaluate research trends. An online survey of 1,005 U.S. consumers investigated appropriate products for insect protein powder incorporation (based on willingness to try; WTT), …

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Small Molecule Inhibitors Of The Bacterioferritin (Bfrb)-Ferredoxin (Bfd) Complex Kill Biofilm-Embedded Pseudomonas Aeruginosa Cells, Anabel Soldano, Huili Yao, Achala N.D. Punchi Hewage, Kevin Meraz, Joel K. Annor-Gyamfi, Richard A. Bunce, Kevin P. Battaile, Scott Lovell, Mario Rivera Jan 2021

Small Molecule Inhibitors Of The Bacterioferritin (Bfrb)-Ferredoxin (Bfd) Complex Kill Biofilm-Embedded Pseudomonas Aeruginosa Cells, Anabel Soldano, Huili Yao, Achala N.D. Punchi Hewage, Kevin Meraz, Joel K. Annor-Gyamfi, Richard A. Bunce, Kevin P. Battaile, Scott Lovell, Mario Rivera

Faculty Publications

© 2020 American Chemical Society. Bacteria depend on a well-regulated iron homeostasis to survive adverse environments. A key component of the iron homeostasis machinery is the compartmentalization of Fe3+ in bacterioferritin and its subsequent mobilization as Fe2+ to satisfy metabolic requirements. In Pseudomonas aeruginosa Fe3+ is compartmentalized in bacterioferritin (BfrB), and its mobilization to the cytosol requires binding of a ferredoxin (Bfd) to reduce the stored Fe3+ and release the soluble Fe2+. Blocking the BfrB-Bfd complex in P. aeruginosa by deletion of the bfd gene triggers an irreversible accumulation of Fe3+ in BfrB, concomitant cytosolic iron deficiency and significant impairment …

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Extreme High-Field Superconductivity In Thin Re Films, F. N. Womack, D. P. Young, D. A. Browne, G. Catelani, J. Jiang, E. I. Meletis, P. W. Adams Jan 2021

Extreme High-Field Superconductivity In Thin Re Films, F. N. Womack, D. P. Young, D. A. Browne, G. Catelani, J. Jiang, E. I. Meletis, P. W. Adams

Faculty Publications

We report the high-field superconducting properties of thin, disordered Re films via magnetotransport and tunneling density of states measurements. Films with thicknesses in the range of 9 to 3 nm had normal-state sheet resistances of ∼0.2kω to ∼1kω and corresponding transition temperatures in the range of 6 to 3 K. Tunneling spectra were consistent with those of a moderate coupling BCS superconductor. Notwithstanding these unremarkable superconducting properties, the films exhibited an extraordinarily high upper critical field. We estimate their zero temperature Hc2 to be more than twice the Pauli limit. Indeed, in 6-nm samples the estimated reduced critical field Hc2/Tc∼5.6T/K …

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Censorship Concerns In College Media: A Multiple Case Study Analysis On The Silencing Of Student Journalists, Haley Nicole Matlock Jan 2021

Censorship Concerns In College Media: A Multiple Case Study Analysis On The Silencing Of Student Journalists, Haley Nicole Matlock

LSU Doctoral Dissertations

The aim of this qualitative study was to conduct a multiple case study that provides an analysis of censorship concerns at campus newspapers affiliated with public, four-year universities. Eighteen individuals from seven institutions participated in interviews. Interviewees consisted of former and current student journalists and advisers who worked at university publications where allegations of censorship have occurred within the last decade. The Student Press Law Center routinely investigates claims of censorship and provides pro bono legal counsel to student journalists (Zagier, 2011). While courts commonly sided with students in disagreements regarding free speech, Hazelwood v Kuhlmeier (1988) scaled back freedoms …

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Are We There Yet? Educators As Lgbtq Advocates And Book Clubs As Professional Development, Alexis Marie Egan Jan 2021

Are We There Yet? Educators As Lgbtq Advocates And Book Clubs As Professional Development, Alexis Marie Egan

LSU Doctoral Dissertations

This dissertation examines Rainbow Advocates: An Educator’s Book Club, a book club study designed for educators wherein they read three works of LGBTQ young adult literature in Summer 2020. Purposes of the book club study include a consideration of how participating educators’ experiences with LGBTQ youth, literary materials, and training compare to past research. This dissertation includes an assessment of their readiness to handle LGBTQ issues in school sites and an evaluation of book clubs and reading LGBTQ young adult literature as a method of professional development for educators. In doing so, this dissertation draws on reader responses as per …

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Label-Free Lipidome Study Of Paraventricular Thalamic Nucleus (Pvt) Of Rat Brain With Post-Traumatic Stress Injury By Raman Imaging, Ardalan Chaichi, Syed Mohammad Abid Hasan, Nishir Mehta, Fabrizio Donnarumma, Philip Ebenezer, Kermit K. Murray, Joseph Francis, Manas Ranjan Gartia Jan 2021

Label-Free Lipidome Study Of Paraventricular Thalamic Nucleus (Pvt) Of Rat Brain With Post-Traumatic Stress Injury By Raman Imaging, Ardalan Chaichi, Syed Mohammad Abid Hasan, Nishir Mehta, Fabrizio Donnarumma, Philip Ebenezer, Kermit K. Murray, Joseph Francis, Manas Ranjan Gartia

Faculty Publications

© 2021 The Royal Society of Chemistry. Post-traumatic stress disorder (PTSD) is a widespread psychiatric injury that develops serious life-threatening symptoms like substance abuse, severe depression, cognitive impairments, and persistent anxiety. However, the mechanisms of post-traumatic stress injury in brain are poorly understood due to the lack of practical methods to reveal biochemical alterations in various brain regions affected by this type of injury. Here, we introduce a novel method that provides quantitative results from Raman maps in the paraventricular nucleus of the thalamus (PVT) region. By means of this approach, we have shown a lipidome comparison in PVT regions …

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Reconfigurable Network For Quantum Transport Simulations, Mario A. Quiroz-Juárez, Chenglong You, Javier Carrillo-Martínez, Diego Montiel-Álvarez, José L. Aragón, Omar S. Magaña-Loaiza, Roberto De J. León-Montiel Jan 2021

Reconfigurable Network For Quantum Transport Simulations, Mario A. Quiroz-Juárez, Chenglong You, Javier Carrillo-Martínez, Diego Montiel-Álvarez, José L. Aragón, Omar S. Magaña-Loaiza, Roberto De J. León-Montiel

Faculty Publications

We put forward a versatile, highly scalable, tunable electronic platform for the simulation of single-excitation quantum transport phenomena. Our system, comprising 10 state-of-the-art, fully reconfigurable electronic oscillators, is implemented by making use of functional blocks synthesized with operational amplifiers and passive linear electrical components. To test the robustness and precise control of our platform, we simulate different quantum transport protocols, such as the ballistic propagation of a single-excitation wave function in an ordered lattice, and its localization due to disorder. We implement the Su-Schrieffer-Heeger model to directly observe the emergence of topologically protected one-dimensional edge states. Furthermore, we present the …

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The Tensile Root Strength Of Spartina Patens Declines With Exposure To Multiple Stressors, R. Eugene Turner, Lauris O. Hollis Jan 2021

The Tensile Root Strength Of Spartina Patens Declines With Exposure To Multiple Stressors, R. Eugene Turner, Lauris O. Hollis

Faculty Publications

Coastal wetlands may be subjected to numerous biotic and abiotic stressors from natural and anthropogenic forces in the landscape. The influx of nutrients, inorganic compounds and xenobiotics are suspected of degrading the belowground biomass of coastal macrophytes. Spartina patens acts as an ecosystem engineer for lower salinity coastal marshes and its biomechanical properties are vital to the stability and resilience of coastal wetlands. S.patens was exposed to one natural (flooding) and two anthropogenic stressors (atrazine and nutrient addition) in a greenhouse experiment to test the hypothesis that these three stressors reduce the tensile root strength of S. patens. A one-way …

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Immobilization Of Cesium And Iodine Into Cs3Bi2I9 Perovskite-Silica Composites And Core-Shell Waste Forms With High Waste Loadings And Chemical Durability, Kun Yang, Weiguang Zhu, Spencer Scott, Yachun Wang, Jianwei Wang, Brian J. Riley, John Vienna, Jie Lian Jan 2021

Immobilization Of Cesium And Iodine Into Cs3Bi2I9 Perovskite-Silica Composites And Core-Shell Waste Forms With High Waste Loadings And Chemical Durability, Kun Yang, Weiguang Zhu, Spencer Scott, Yachun Wang, Jianwei Wang, Brian J. Riley, John Vienna, Jie Lian

Faculty Publications

© 2020 Elsevier B.V. Cs3Bi2I9, a defect perovskite derivative, is a potential host phase to immobilize iodine and cesium with high waste loadings. In this work, two strategies were explored to form Cs3Bi2I9-silica composites and a core-shell structure in order to improve chemical durability of waste form materials meanwhile maintaining high waste loadings. Cs3Bi2I9 loadings as high as 70 wt.% were incorporated into a silica matrix to form silica-ceramic composites, and 20 wt.% Cs3Bi2I9 was encapsulated into silica to form a core–shell structure by low temperature spark plasma sintering. Chemical durability of the composite and core-shell waste forms was evaluated …

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Mutant Tp53 Interacts With Bcar1 To Contribute To Cancer Cell Invasion, Alvin Kunyao Guo, Yoko Itahana, Veerabrahma Pratap Seshachalam, Hui Ying Chow, Sujoy Ghosh, Koji Itahana Jan 2021

Mutant Tp53 Interacts With Bcar1 To Contribute To Cancer Cell Invasion, Alvin Kunyao Guo, Yoko Itahana, Veerabrahma Pratap Seshachalam, Hui Ying Chow, Sujoy Ghosh, Koji Itahana

Division of Basic Science Faculty Publications

Background: Mutant TP53 interacts with other proteins to produce gain-of-function properties that contribute to cancer metastasis. However, the underlying mechanisms are still not fully understood. Methods: Using immunoprecipitation and proximity ligation assays, we evaluated breast cancer anti-estrogen resistance 1 (BCAR1) as a novel binding partner of TP53R273H, a TP53 mutant frequently found in human cancers. The biological functions of their binding were examined by the transwell invasion assay. Clinical outcome of patients was analysed based on TP53 status and BCAR1 expression using public database. Results: We discovered a novel interaction between TP53R273H and BCAR1. We found that BCAR1 translocates from …

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The Inaugural Issue Of Ornithology, T. Scott Sillett, Wesley M. Hochachka, Sabrina S. Taylor Jan 2021

The Inaugural Issue Of Ornithology, T. Scott Sillett, Wesley M. Hochachka, Sabrina S. Taylor

Faculty Publications

No abstract provided.

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Switching Between Singular Points In Non-Pt -Symmetric Multilayer Structures Using Phase-Change Materials, Yin Huang, Lanyan Wang, Yuecheng Shen, Georgios Veronis Jan 2021

Switching Between Singular Points In Non-Pt -Symmetric Multilayer Structures Using Phase-Change Materials, Yin Huang, Lanyan Wang, Yuecheng Shen, Georgios Veronis

Faculty Publications

We investigate the switching between singular points in non-parity-time-symmetric multilayer structures using phase-change materials at the optical communication wavelength. We first show that absorbing singularities can be switched to exceptional points (EPs) in a two-layer structure consisting of a phase-change material layer and a lossy layer by switching the phase-change material Ge2Sb2Te5 (GST) from its crystalline to its amorphous phase. We also show that spectral singularities (SSs) can be switched to EPs in a three-layer structure consisting of a lossless dielectric layer sandwiched between a GST layer and a gain layer by switching the GST from its crystalline to its …

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Estuarine Oiling Increases A Long-Term Decline In Mussel Growth*, R. Eugene Turner, Jennifer S. Spicer Jan 2021

Estuarine Oiling Increases A Long-Term Decline In Mussel Growth*, R. Eugene Turner, Jennifer S. Spicer

Faculty Publications

The ribbed mussel, Geukensia granosissima, cycles nutrients, contributes to soil stability, and can be a major component of predator-prey communities in salt marshes. Mussels were exposed to the 2010 Deepwater Horizon oil spill in the Gulf of Mexico, and salt marshes remain contaminated eight years later. We hypothesized that the oiled mussels had reduced annual growth, altered population size frequency, and perhaps changed valve morphometrics. We sampled 10 marshes near Port Sulphur, LA, to measure the morphometrics of 133 mussels and their age-specific growth rate, and also the marsh oil content and percent vegetative cover. The relationships between valve weight, …

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Phosphorus Concentrations Into A Subtropical Lake Strongly Influence Nitrogen Accumulation, Nitrogen Export, And Chl A Concentrations, R. Eugene Turner, J M. Lee, C S. Milan, E M. Swenson Jan 2021

Phosphorus Concentrations Into A Subtropical Lake Strongly Influence Nitrogen Accumulation, Nitrogen Export, And Chl A Concentrations, R. Eugene Turner, J M. Lee, C S. Milan, E M. Swenson

Faculty Publications

We measured water quality monthly for 22 years in water entering, within, and exiting a 65 km(2) shallow polymictic and eutrophic freshwater lake in the northern Gulf of Mexico. Fertilizer use in the watershed is the dominate source of phosphorous (P) going into the lake and controls the lake's P concentrations, but nitrogen (N) fertilizer use was not related to total nitrogen concentration in the lake. Half of the particulate P entering the lake is trapped within it and there is a net accumulation of N that appears to be from the stimulation of nitrogen fixation. The lake's concentration of …

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Characterization Of Common Phytoplankton On The Louisiana Shelf, M L. Parsons, A L. Brandt, R. Eugene Turner, W L. Morrison, M L. Parsons Jan 2021

Characterization Of Common Phytoplankton On The Louisiana Shelf, M L. Parsons, A L. Brandt, R. Eugene Turner, W L. Morrison, M L. Parsons

Faculty Publications

Phytoplankton and accompanying environmental data (temperature, salinity, secchi depth, stratification, and inorganic nutrients) were analyzed from 672 surface water samples (0 to 1.5 m depth) collected from 95 stations located on the Louisiana shelf between April 1990 and August 2011. Phytoplankton were identified to the lowest practical taxonomic unit from glutaraldehyde-preserved samples using epifluorescent microscopy and reported as cells L-1. Twenty-six phytoplankton taxa (primarily diatoms) that were 8 mu m in size, identified to genuslevel resolution and ranked in the top 20 in at least one of three separate categories (average abundance; frequency of occurrence; and bloom frequency) were used …

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Declining Bacteria, Lead, And Sulphate, And Rising Ph And Oxygen In The Lower Mississippi River, R. Eugene Turner Jan 2021

Declining Bacteria, Lead, And Sulphate, And Rising Ph And Oxygen In The Lower Mississippi River, R. Eugene Turner

Faculty Publications

Various air and water pollution issues in the US were confronted in the last 60 years using national policy legislation, notably the Clean Water Act and the Clean Air Act. I examine changes in the concentrations of bacteria, oxygen, lead, and sulphate at the terminus of the Mississippi River before and after these pollution abatement efforts. Microbial concentrations increased or were stable from 1909 to 1980 but decreased about 3 orders of magnitude after the 1970s, while the average oxygen content increased. A large decline in lead concentration occurred after the 1960s, along with a less dramatic decline in sulphate …

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Climate Change Implications For Tidal Marshes And Food Web Linkages To Estuarine And Coastal Nekton, D D. Colombano, S. Y. Litvin, S. L. Ziegler, S. B. Alford, D. D. Colombano, M. A. Barbeau, J. Cebrian, R. M. Connolly, C. A. Currin, L. A. Deegan, J. S. Lesser, C. W. Martin, A. E. Mcdonald, C. Mcluckie, B. H. Morrison, J. W. Pahl, L. W. Risse, J. A. Smith, L. W. Staver, R. Eugene Turner, N. J. Waltham Jan 2021

Climate Change Implications For Tidal Marshes And Food Web Linkages To Estuarine And Coastal Nekton, D D. Colombano, S. Y. Litvin, S. L. Ziegler, S. B. Alford, D. D. Colombano, M. A. Barbeau, J. Cebrian, R. M. Connolly, C. A. Currin, L. A. Deegan, J. S. Lesser, C. W. Martin, A. E. Mcdonald, C. Mcluckie, B. H. Morrison, J. W. Pahl, L. W. Risse, J. A. Smith, L. W. Staver, R. Eugene Turner, N. J. Waltham

Faculty Publications

Climate change is altering naturally fluctuating environmental conditions in coastal and estuarine ecosystems across the globe. Departures from long-term averages and ranges of environmental variables are increasingly being observed as directional changes [e.g., rising sea levels, sea surface temperatures (SST)] and less predictable periodic cycles (e.g., Atlantic or Pacific decadal oscillations) and extremes (e.g., coastal flooding, marine heatwaves). Quantifying the short- and long-term impacts of climate change on tidal marsh seascape structure and function for nekton is a critical step toward fisheries conservation and management. The multiple stressor framework provides a promising approach for advancing integrative, cross-disciplinary research on tidal …

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Salt Marsh Elevation Limit Determined After Subsidence From Hydrologic Change And Hydrocarbon Extraction, R. Eugene Turner, Yu Mo Jan 2021

Salt Marsh Elevation Limit Determined After Subsidence From Hydrologic Change And Hydrocarbon Extraction, R. Eugene Turner, Yu Mo

Faculty Publications

Levee construction aboveground and hydrocarbon removal from belowground in coastal wetlands can create hydrologic changes that increase plant stress through flooding. But the significance of the subsidence they cause individually or in combination is contested. This study untangled them to demonstrate elevational limits of salt marshes by studying dredged and natural waterways in two salt marshes in Louisiana, USA. The areas had a homogenous plant cover before drilling for oil and gas extraction peaked in the 1960s, and now are a mixed network of natural waterways and dredged canals used to drill wells with an average drill date of 1965.8 …

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Marginal Warming Associated With A Covid-19 Quarantine And The Implications For Disease Transmission, P. W. Miller, C. Reesman, M. K. Grossman, S. A. Nelson, V. Liu, P. Wang Jan 2021

Marginal Warming Associated With A Covid-19 Quarantine And The Implications For Disease Transmission, P. W. Miller, C. Reesman, M. K. Grossman, S. A. Nelson, V. Liu, P. Wang

Faculty Publications

During January-February 2020, parts of China faced restricted mobility under COVID-19 quarantines, which have been associated with improved air quality. Because particulate pollutants scatter, diffuse, and absorb incoming solar radiation, a net negative radiative forcing, decreased air pollution can yield surface warming. As such, this study (1) documents the evolution of China's January-February 2020 air temperature and concurrent particulate changes; (2) determines the temperature response related to reduced particulates during the COVID-19 quarantine (C19Q); and (3) discusses the conceptual implications for temperature-dependent disease transmission. C19Q particulate evolution is monitored using satellite analyses, and concurrent temperature anomalies are diagnosed using surface …

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Early Diagenesis In The Hypoxic And Acidified Zone Of The Northern Gulf Of Mexico: Is Organic Matter Recycling In Sediments Disconnected From The Water Column?, C. Rabouille, B. Lansard, S.M. Owings, N.N. Rabalais, B. Bombled, E. Metzger, J. Richirt, E.M. Eitel, A.D. Boever, J.S. Beckler, M. Taillefert Jan 2021

Early Diagenesis In The Hypoxic And Acidified Zone Of The Northern Gulf Of Mexico: Is Organic Matter Recycling In Sediments Disconnected From The Water Column?, C. Rabouille, B. Lansard, S.M. Owings, N.N. Rabalais, B. Bombled, E. Metzger, J. Richirt, E.M. Eitel, A.D. Boever, J.S. Beckler, M. Taillefert

Faculty Publications

No abstract provided.

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