Physical Sciences and Mathematics Commons^™

Does A Bottom-Up Mechanism Promote Hypoxia In The Mississippi Bight?, Virginie Sanial, Willard S. Moore, Alan M. Shiller

Faculty Publications

The Mississippi Bight, east of the Mississippi River, is a complex coastal ecosystem that, like the better-known Louisiana Shelf to the west, experiences seasonal bottom water hypoxia. However, input of allochthonous nutrients from the Mississippi River to the Mississippi Bight appears to be limited, begging the question of what drives seasonal hypoxia in this system. Prior research has suggested submarine groundwater discharge (SGD) could be an overlooked component of the Mississippi Bight biogeochemical system. We thus examined the hypothesis that SGD provides a “bottom up” driver for seasonal hypoxia in this area. We used a multi-tracer approach based on known …

Heteroacene-Based Amphiphile As A Molecular Scaffold For Bioimaging Probes, Tharindu A. Ranathunge, Mahesh Loku Yaddehige, Jordan H. Varma, Cameron Smith, Jay Nguyen, Iyanuoluwani Owolabi, Wojciech Kolodziejczyk, Nathan I. Hammer, Glake Hill, Alex Flynt, Davita L. Watkins

Faculty Publications

The challenges faced with current fluorescence imaging agents have motivated us to study two nanostructures based on a hydrophobic dye, 6H-pyrrolo[3,2-b:4,5-b’]bis [1,4]benzothiazine (TRPZ). TRPZ is a heteroacene with a rigid, pi-conjugated structure, multiple reactive sites, and unique spectroscopic properties. Here we coupled TRPZ to a tert-butyl carbamate (BOC) protected 2,2-bis(hydroxymethyl)propanoic acid (bisMPA) dendron via azide-alkyne Huisgen cycloaddition. Deprotection of the protected amine groups on the dendron afforded a cationic terminated amphiphile, TRPZ-bisMPA. TRPZ-bisMPA was nanoprecipitated into water to obtain nanoparticles (NPs) with a hydrodynamic radius that was <150 nm. For comparison, TRPZ-PG was encapsulated in pluronic-F127 (Mw …

Swir Emissive Rosindolizine Dyes With Nanoencapsulation In Water Soluble Dendrimers, Satadru Chatterjee, William E. Meador, Cameron Smith, Indika Chandrasiri, Mohammad Farid Zia, Jay Nguyen, Austin Dorris, Alex Flynt, Davita L. Watkins, Nathan I. Hammer, Jared H. Delcamp

Faculty Publications

Shortwave infrared (SWIR) emission has great potential for deep-tissue in vivo biological imaging with high resolution. In this article, the synthesis and characterization of two new xanthene-based RosIndolizine dyes coded ^PhRosIndz and ^tolRosIndz is presented. The dyes are characterized via femtosecond transient absorption spectroscopy as well as steady-state absorption and emission spectroscopies. The emission of these dyes is shown in the SWIR region with peak emission at 1097 nm. ^TolRosIndz was encapsulated with an amphiphilic linear dendritic block co-polymer (LDBC) coded 10-PhPCL-G3 with high uptake yield. Further, cellular toxicity was examined in vitro using HEK (human embryonic …

Maximal Spacelike Surfaces In A Certain Homogeneous Lorentzian 3-Manifold, Sungwook Lee

Faculty Publications

The 2-parameter family of certain homogeneous Lorentzian 3-manifolds, which includes Minkowski 3-space and anti-de Sitter 3-space, is considered. Each homogeneous Lorentzian 3-manifold in the 2-parameter family has a solvable Lie group structure with left invariant metric. A generalized integral representation formula for maximal spacelike surfaces in the homogeneous Lorentzian 3-manifolds is obtained. The normal Gauß map of maximal spacelike surfaces and its harmonicity are discussed.

Site Selection For Coral Reef Restoration Using Airborne Imaging Spectroscopy, Steven R. Schill, Gregory P. Asner, Valerie Pietsch Mcnulty, F. Joseph Pollock, Aldo Croquer, Nicholas R. Vaughn, Ximena Escovar-Fadul, George Raber, Elizabeth Shaver

Faculty Publications

Over the past decade, coral restoration efforts have increased as reefs continue to decline at unprecedented rates. Identifying suitable coral outplanting locations to maximize coral survival continues to be one of the biggest challenges for restoration practitioners. Here, we demonstrate methods of using derivatives from imaging spectroscopy from the Global Airborne Observatory (GAO) to identify suitable coral outplant sites and report on the survival rates of restored coral at those sites. Outplant sites for a community-based, citizen science outplant event in Bávaro, Dominican Republic, were identified using expert-defined criteria applied to a suitability model from data layers derived from airborne …

Molecular Markers Of Biogenic And Oil-Derived Hydrocarbons In Deep-Sea Sediments Following The Deepwater Horizon Spill, Isabel C. Romero, Jeffrey P. Chanton, Gregg Brooks, Samantha Bosman, Rebekka A. Larson, Austin Harris, Patrick Schwing, Arne Diercks

Faculty Publications

Following the Deepwater Horizon oil spill (DWHOS), the formation of an unexpected and extended sedimentation event of oil-associated marine snow (MOSSFA: Marine Oil Snow Sedimentation and Flocculent Accumulation) demonstrated the importance of biology on the fate of contaminants in the oceans. We used a wide range of compound-specific data (aliphatics, hopanes, steranes, triaromatic steroids, polycyclic aromatics) to chemically characterize the MOSSFA event containing abundant and multiple hydrocarbon sources (e.g., oil residues and phytoplankton). Sediment samples were collected in 2010–2011 (ERMA-NRDA programs: Environmental Response Management Application – Natural Resource Damage Assessment) and 2018 (REDIRECT project: Resuspension, Redistribution and Deposition of Deepwater …

Resuspension, Redistribution, And Deposition Of Oil-Residues To Offshore Depocenters After The Deepwater Horizon Oil Spill, Arne R. Diercks, Isabel C. Romero, Rebekka A. Larson, Patrick Schwing, Austin Harris, Samantha Bosman, Jeffrey P. Chanton, Gregg Brooks

Faculty Publications

The focus of this study was to determine the long-term fate of oil-residues from the 2010 Deepwater Horizon (DwH) oil spill due to remobilization, transport, and re-distribution of oil residue contaminated sediments to down-slope depocenters following initial deposition on the seafloor. We characterized hydrocarbon residues, bulk sediment organic matter, ease of resuspension, sedimentology, and accumulation rates to define distribution patterns in a 14,300 km2 area southeast of the DwH wellhead (1,500 to 2,600 m water depth). Oil-residues from the DwH were detected at low concentrations in 62% of the studied sites at specific sediment layers, denoting episodic deposition of oil-residues …

St-V-Net: Incorporating Shape Prior Into Convolutional Neural Netwoks For Proximal Femur Segmentation, Chen Zhao, Joyce H. Keyak, Jinshan Tang, Tadashi S. Kaneko, Sundeep Khosla, Shreyasee Amin, Elizabeth J. Atkinson, Lan-Juan Zhao, Michael J. Serou, Chaoyang Zhang, Hui Shen, Hong-Wen Deng, Weihua Zhou

Faculty Publications

We aim to develop a deep-learning-based method for automatic proximal femur segmentation in quantitative computed tomography (QCT) images. We proposed a spatial transformation V-Net (ST-V-Net), which contains a V-Net and a spatial transform network (STN) to extract the proximal femur from QCT images. The STN incorporates a shape prior into the segmentation network as a constraint and guidance for model training, which improves model performance and accelerates model convergence. Meanwhile, a multi-stage training strategy is adopted to fine-tune the weights of the ST-V-Net. We performed experiments using a QCT dataset which included 397 QCT subjects. During the experiments for the …

Short-Term Impacts Of 2017 Western North American Wildfires On Meteorology, The Atmosphere's Energy Budget, And Premature Mortality, Diana N. Bernstein, Douglas S. Hamilton, Rosalie Krasnoff, Natalie M. Mahowald, David S. Connelly, Simone Tilmes, Peter G.M. Hess

Faculty Publications

Western North American fires have been increasing in magnitude and severity over the last few decades. The complex coupling of fires with the atmospheric energy budget and meteorology creates short-term feedbacks on regional weather altering the amount of pollution to which Americans are exposed. Using a combination of model simulations and observations, this study shows that the severe fires in the summer of 2017 increased atmospheric aerosol concentrations leading to a cooling of the air at the surface, reductions in sensible heat fluxes, and a lowering of the planetary boundary layer height over land. This combination of lower-boundary layer height …

Characterization Of The Differential Expressed Genes And Transcriptomic Pathway Analysis In The Liver Of Sub-Adult Red Drum (Sciaenops Ocellatus) Exposed To Deepwater Horizon Chemically Dispersed Oil, Tracy A. Sherwood, Maria L. Rodgers, Andrea M. Tarnecki, Dana L. Wetzel

Faculty Publications

The Deepwater Horizon blowout resulted in the second-largest quantity of chemical dispersants used as a countermeasure for an open water oil spill in the Gulf of Mexico. Of which, the efficacy of dispersant as a mitigation strategy and its toxic effects on aquatic fauna remains controversial. To enhance our understanding of potential sub-lethal effects of exposure to chemically dispersed-oil, sub-adult red drum (Sciaenops ocellatus) were continuously exposed to a Corexit 9500: DWH crude oil chemically enhanced water accommodated fraction (CEWAF) for 3-days and transcriptomic responses were assessed in the liver. Differential expressed gene (DEG) analysis demonstrated that 63 …

Engineering Donor-Acceptor Conjugated Polymers For High-Performance And Fast-Response Organic Electrochemical Transistors, Hanyu Jia, Zhen Huang, Peiyun Li, Song Zhang, Yunfei Wang, Jie Yu Wang, Xiaodan Gu, Ting Lei

Faculty Publications

To date, high-performance organic electrochemical transistors (OECTs) have mostly been based on polythiophene systems. Donor–acceptor (D–A) conjugated polymers are expected to be promising materials for OECTs owing to their high mobility and comparatively low crystallinity (good for ion diffusion). However, the OECT performance of D–A polymers lags far behind that of the polythiophenes. Here we synergistically engineered the backbone and side chain of a series of diketopyrrolopyrrole (DPP)-based D–A polymers and found that redox potential, molecular weight, solution processability, and film microstructures all have a severe impact on their performance. After systematic engineering, P(bgDPP-MeOT2) exhibited the best figure-of-merit (μC …

Heterogeneous Co2And Ch4Content Of Glacial Meltwater From The Greenland Ice Sheet And Implications For Subglacial Carbon Processes, Andrea J. Pain, Jonathan B. Martin, Ellen E. Martin, Åsa K. Rennermalm, Shaily Rahman

Faculty Publications

Accelerated melting of the Greenland Ice Sheet has increased freshwater delivery to the Arctic Ocean and amplified the need to understand the impact of Greenland Ice Sheet meltwater on Arctic greenhouse gas budgets. We evaluate subglacial discharge from the Greenland Ice Sheet for carbon dioxide (CO₂) and methane (CH₄) concentrations and δ¹³C values and use geochemical models to evaluate subglacial CH₄ and CO₂ sources and sinks. We compare discharge from southwest (a sub-catchment of the Isunnguata Glacier, sub-Isunnguata, and the Russell Glacier) and southern Greenland (Kiattut Sermiat). Meltwater CH₄ concentrations vary …

Using Multiple Ecological Models To Inform Environmental Decision-Making, Kristy A. Lewis, Kenneth A. Rose, Kim De Mutsert, Shaye Sable, Cameron Ainsworth, Damian C. Brady, Howard Townsend

Faculty Publications

Coastal ecosystems are experiencing degradation from compound impacts of climate change and multiple anthropogenic disturbances. These pressures often act synergistically and complicate designing effective conservation measures; consequently, large-scale coastal restoration actions become a wicked problem. The purpose of this study was to use two different food web models in a coordinated manner to inform resource managers in their assessment of the ecological effects of a large-scale marsh restoration project. A team was formed that included the model developers and outside scientists, who were asked to use available model results of the calibrated simulations of an Ecopath with Ecosim (EwE) model …

Prospects For Gulf Of Mexico Environmental Recovery And Restoration, Denis A. Wiesenburg, Bob Shipp, F. Joel Fodrie, Sean Powers, Julien Lartigue, Kelly M. Darnell, Melissa M. Baustian, Cam Ngo, John F. Valentine, Kateryna Wowk

Faculty Publications

Previous oil spills provide clear evidence that ecosystem restoration efforts are challenging, and recovery can take decades. Similar to the Ixtoc 1 well blowout in 1979, the Deepwater Horizon (DWH) oil spill was enormous both in volume of oil spilled and duration, resulting in environmental impacts from the deep ocean to the Gulf of Mexico coastline. Data collected during the National Resource Damage Assessment showed significant damage to coastal areas (especially marshes), marine organisms, and deep-sea habitat. Previous spills have shown that disparate regions recover at different rates, with especially long-term effects in salt marshes and deepsea habitat. Environmental recovery …

End-To-End Modeling Reveals Species-Specific Effects Of Large-Scale Coastal Restoration On Living Resources Facing Climate Change, Kim De Mutsert, Kristy A. Lewis, Eric D. White, Joe Buszowski

Faculty Publications

Coastal erosion and wetland loss are affecting Louisiana to such an extent that the loss of land between 1932 and 2016 was close to 5,000 km². To mitigate this decline, coastal protection and restoration projects are being planned and implemented by the State of Louisiana, United States. The Louisiana Coastal Master Plan (CMP) is an adaptive management approach that provides a suite of projects that are predicted to build or maintain land and protect coastal communities. Restoring the coast with this 50-year large-scale restoration and risk reduction plan has the potential to change the biomass and distribution of …

A Synthesis Of Deepwater Horizon Impacts On Coastal And Nearshore Living Marine Resources, Steven A. Murawski, Joshua P. Kilborn, Adriana C. Bejarano, David Chagaris, David Donaldson, Frank J. Hernandez, Timothy C. Macdonald, Craig Newton, Ernst Peebles, Kelly L. Robinson

Faculty Publications

The 2010 Deepwater Horizon (DWH) oil blowout in the Gulf of Mexico began on April 20, originating in the deep sea 66 km off the Louisiana coast. By early June, DWH oil had spread to coastal Louisiana, Mississippi, Alabama and western Florida. An estimated 2,113 km of shoreline were oiled, making DWH the largest marine oil spill in global history by length of affected shoreline. Additionally, a series of oil spill response measures were deployed, including diversions of Mississippi River discharge to forestall oil coming ashore, and the establishment of large-scale fishery closures, with both affecting coastal resources to varying …

Accuracy Assessment Of Global Internal-Tide Models Using Satellite Altimetry, Loren Carrere, Brian K. Arbic, Brian Dushaw, Gary Egbert, Svetlana Erofeeva, Florent Lyard, Richard D. Ray, Clement Ubelmann, Edward Zaron, Zhongxiang Zhao, Jay F. Shriver, Maarten Cornelis Buijsman, Nicolas Picot

Faculty Publications

Altimeter measurements are corrected for several geophysical parameters in order to access ocean signals of interest, like mesoscale or sub-mesoscale variability. The ocean tide is one of the most critical corrections due to the amplitude of the tidal elevations and to the aliasing phenomena of high-frequency signals into the lower-frequency band, but the internal-tide signatures at the ocean surface are not yet corrected globally.

Internal tides can have a signature of several centimeters at the surface with wavelengths of about 50–250 km for the first mode and even smaller scales for higher-order modes. The goals of the upcoming Surface Water …

Commuting Perturbations Of Operator Equations, Xue Xu, Jiu Ding

Faculty Publications

Let X be a Banach space and let T: X →X be a bounded linear operator with closed range. We study a class of commuting perturbations of the corresponding operator equation, using the concept of the spectral radius of a bounded linear operator. Our results extend the classic perturbation theorem for invertible operators and its generalization for arbitrary operators under the commutability assumption.

Dicer Represses The Interferon Response And The Double-Stranded Rna-Activated Protein Kinase Pathway In Mouse Embryonic Stem Cells, Chandan Gurung, Mona Fendereski, Krishna Sapkota, Jason Guo, Faqing Huang, Yan Lin Guo

Faculty Publications

Recent studies have demonstrated that embryonic stem cells (ESCs) are deficient in expressing type I interferons (IFN), the cytokines that play key roles in antiviral responses. However, the underlying molecular mechanisms and biological implications of this finding are poorly understood. In this study, we developed a synthetic RNA-based assay that can simultaneously assess multiple forms of antiviral responses. Dicer is an enzyme essential for RNA interference (RNAi), which is used as a major antiviral mechanism in invertebrates. RNAi activity is detected in wild-type ESCs but is abolished in Dicer knockout ESCs (D-/-ESCs) as expected. Surprisingly, D-/-ESCs have gained the ability …

Policy Interactions In Large-Scale Marine Protected Areas, Rebecca L. Gruby, Noella J. Gray, Luke Fairbanks, Elizabeth Havice, Lisa M. Campbell, Alan Friedlander, Kirsten L.L. Oleson, King Sam, Lillian Mitchell, Quentin Hanich

Faculty Publications

Large-scale marine protected areas (LSMPAs) have proliferated in recent years, now accounting for most of the world's MPA coverage. However, little is known about LSMPA outcomes and the factors that affect them. Here we argue that policy interactions—the cumulative effect of co-existing policies for an issue and/or geographical area—can play a critical, but under-recognized, role in influencing LSMPA design and outcomes. We analyze interactions between national LSMPAs within Palau and Kiribati, and regional fisheries management established by the Nauru Agreement to show how policy actors can account for policy interactions in LSMPA design, and to demonstrate the profound influence that …

Privacy-Preserving Non-Participatory Surveillance System For Covid-19-Like Pandemics, Mahmoud Nabil, Ahmed Sherif, Mohamed Mahmoud, Waleed Alsmary, Maazen Alsabaan

Faculty Publications

COVID-19 pandemic has revealed a pressing need for an effective surveillance system to control the spread of infection. However, the existing systems are run by the people’s smartphones and without a strong participation from the people, the systems become ineffective. Moreover, these systems can be misused to spy on people and breach their privacy. Due to recent privacy breaches, people became anxious about their privacy, and without privacy reassurance, the people may not accept the systems. In this paper, we propose a non-participatory privacy-preserving surveillance system for COVID-19-like pandemics. The system aims to control the spread of COVID-19 infection without …

Direct Determination Of Absolute Stereochemistry Of Α-Methylselenocysteine Using The Mosher Method, Robert J. Wehrle, Douglas R. Powell, Douglas S. Masterson

Faculty Publications

Mosher amides of α-methylselenocysteine were synthesized to determine the absolute stereochemistry of the sterically hindered α-carbon utilizing ¹H, ¹³C, ¹⁹F, and ⁷⁷Se NMR spectroscopies. After analysis of these spectra using the established Mosher method, the stereochemistry of the α-carbon was determined to be (R), which was subsequently confirmed using x-ray crystallography.