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Analysis of Vector Sensor Data Collected in Gulf of Mexico
Get PDFIn 2015, the Naval Oceanographic Office collected vector sensor data in approximately 100 meters of water southwest of Panama City, Florida in the Gulf of Mexico. The vector sensor was deployed at a center mass height of one foot above the seafloor and de-coupled from its mooring through lightweight springs to measure local acoustical pressure and particle velocity.
Accuracy of the data across frequency and source azimuth is measured by evaluating acoustical impedance as a function of frequency and source azimuthal direction. Results indicate the vector sensor has an effective band from 50 to 450 Hz with mooring reflections and resonances degrading performance above this band. Localization using three spatial processing methods are analyzed for high and low Signal to Noise Ratio (SNR) sources. Directional accuracy is approximately 3 degrees up to 350 Hz and 10 degrees above 350 Hz.
Noise sources from air guns, ships, and mammals are spatially processed and the results show that the vector sensor is capable of discriminating the location of two high SNR sources in the environment that are sufficiently separated in either location, time, or frequency
Applied Molecular Dynamics: from Targeting Viral Helicases, to Understanding the Interactions of Cucurbituril Complexes in Ionic Solutions
Get PDFMolecular Dynamics simulations are a highly useful tool in helping understand the fundamental interactions present in a variety of chemical systems. The work discussed here illustrates it’s use in determining the conformational dynamics of the Zika and SARS-Cov-2 helicase in a physiological environment, largely in an effort to discover inhibitors capable of rendering the protein inert. Additionally, we show how it can be used to understand paradoxical trends in the anion-induced precipitation of Cucurbituril cavitands.
Viral helicases are motor proteins tasked with unwinding the viral dsRNA, a crucial step in preparing the strand to be translatable by host cells. By virtue of this function, it is vital and necessary for the pathogen to replicate and successfully carry the infection forward. Given this role, helicases are now becoming a topic of many research efforts primarily centered around the discovery of compounds targeting these enzymes. Through a combination of drug docking, molecular dynamics simulations, and the computation of binding energies, these studies revealed a list of potential inhibitors of the helicases of both the Zika virus and the SARS-Cov-2 virus responsible for causing COVID-19.
Cucurbiturils are widely studied cavitands that readily encapsulate smaller molecules, forming ”host-guest” inclusion complexes with charged, yet predominantly hydrophobic guests. The 7-monomer macrocycle (CB7) is of particular interest given its high solubility in aqueous solutions, making it one of the more investigated cavitands in modern supramolecular chemistry. These studies aimed to better understand how these complexes behave in ionic solutions. Specifically, molecular dynamics simulations were performed to explain current paradigms in the Hofmeister series when precipitating CB7. The data revealed that hexafluorophosphate is most likely to bind at the charged crowns (likely neutralizing it and promoting crystallization), while iodide associated mostly with the exterior, hydrophobic surfaces of CB7 (likely increasing the solubility). Both findings are consistent with experimentally derived critical precipitation concentrations (CPC) of these anions, serving as a reliable explanation for their deviations from the traditional Hofmeister series
Thermo-Fluid Characterizations of the Powder-Bed Fusion Additive Manufacturing Processes using Laser and Electron Beam
Get PDFThe powder-bed fusion (PBF) process is a subdivision of Additive Manufacturing (AM) technology where a heat source at a controlled speed selectively fuses regions of a powder-bed material to form three-dimensional (3-D) parts. Two of the most effective PBF processes are selective laser melting (SLM) and electron beam additive manufacturing (EBAM), which can fabricate full-density metallic parts in a layer-by-layer fashion. In this study, thermal behavior and melt-pool dynamics in the PBF process are investigated by developing 3-D multiphysics-based thermo-fluid models for both SLM and EBAM, containing Ti-6Al-4V alloy as a powder-bed material. The laser and electron beams are modeled as conical volumetric heat sources having the Gaussian distribution. The temperature-dependent properties of Ti-6Al-4V and the heat source parameters are incorporated in the models as the user-defined functions. The melt-pool geometry and its thermo-fluid behavior are investigated numerically using computational fluid dynamics, and results for temperature profile, variation in thermo-physical properties, the melt-pool velocity and geometry, and cooling rate are obtained under various heat source specifications. The modeling results for SLM and EBAM under the same irradiation conditions are compared to describe their deterministic features to be considered for industrial applications. The comparison shows that under the same energy density and beam interaction time, the SLM process gives a smaller melt-pool volume but a faster average cooling rate than those in the EBAM process. The thermo-fluid models are validated by comparing the simulation results for the melt-pool geometry with experimental results and resembling the numerical melt-front position with the analytical solution for the classical Stephan problem of melting of a phase-change material
Studies directed toward the development of transition metal@halloysite nanocomposite materials for organic transformations
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Regulatory Impacts on U.S. Financial Institutions
No full textIn this paper, I examine data from 2000 to 2019 to assess the impact of banks’ regulations on the U.S. financial institutions’ performance. The first essay examines the impact of the Dodd-Frank Act on the U.S. banking industry. The findings show that the Dodd-Frank Act has a negative impact on banks’ profits, efficiency, solvency and cost of intermediation, the effect is stronger for smaller banks. The act shrinks the advantage of banks that are members of bank holding company compared to standalone banks. Capital requirements are associated with higher profitability, efficiency, and cost of intermediation, while assets liquidity ratio has a negative impact. The second essay examines the impact of abolishing the Office of Thrift Supervision (OTS) on the U.S. savings and loan industry. Under Title III of the Dodd-Frank Act, the OTS is abolished and its responsibilities reassigned to OCC, FDIC, and Fed. Some critics view the Dodd-Frank Act is disproportionately affecting thrifts by keeping the restriction on thrifts’ portfolio structure (QTL test), while the act shrinks some of thrifts’ advantages over commercial banks. My findings show that on average thrifts are less profitable, efficient, and solvent than commercial banks. However, the performance difference between thrifts and commercial banks shrank under the Dodd-Frank Act compared to the period before the act. Nevertheless, after the OTS was abolished, thrifts endured higher cost of compliance
Modeling of Distributary Channels Formed by a Large Sediment Diversion in Broken Marshland
Get PDFA 2-D DELFT3D model was developed to address the morphological response of Barataria Bay, the sediment deposition rate in the receiving basin, and the impact on the existing distributary channels within the broken marsh system due to the proposed Mid-Barataria Sediment Diversion. The model had a mesh size sufficient to accurately represent the development of the distributary channels, localized flooding, erosion, and salinity in the basin. The model predicts that the receiving basin will experience extensive erosion during the first year the diversion is open creating three major distributary pathways which flood much of the basin in freshwater. Most locations experience peak flood stage when the diversion reaches its peak capacity after which flood stage tends to decrease. The area of open water near the diversion opening will experience higher suspended sediment concentrations than those in the diversion due to the erosion of the receiving basin
Black Expressions of Dillard University: How One Historically Black College Pioneered African American Arts
Get PDFThe proposed public history project, Within These Walls (WTW), will be one component of a larger exhibit produced by Dillard University’s, Library Archives and Special Collections entitled The Star Burns Bright: History of Dillard’s Theatrical and Musical Arts, Faculty and Students. WTW will focus on Dillard’s historic African American faculty, students and alumni who became prominent painters, musicians, writers, actors and directors among them Adella Gautier, Randolph Edmonds, Ted Shine Frederick Hall, Theodore Gilliam, and Brenda Osbey. This exhibit will also highlight the many art programs, across genres, offered at the university between 1935 and 1970. This exhibit will demonstrate that art education at Dillard was key to student resilience and empowerment in the face of segregation and the racial struggles of the 1930s through the 1970s. The exhibit is scheduled to open at Dillard University’s Will. W. Alexander Library in Gentilly in June of 2020 and will run through September 2020