Physical Sciences and Mathematics Commons^™

Photocatalytic Degradation Of Simazine Under Visible Light Using Zinc Oxide/Molybdenum Disulfide Heterostructures, Alexandria Castillo

Theses and Dissertations

The photocatalytic degradation of simazine under visible light by using ZnO/MoS2 heterostructures was investigated. Reaction parameters studied to optimize simazine degradation included pH, loading mass of the photocatalyst, and percentage of MoS2 in the heterostructure. pH 2 was the optimal environment for the degradation reaction of all catalysts. A loading mass of 20 mg for each of the ZnO/MoS2 photocatalysts was determined to be the most effective for in the degradation process. The degradation reactions were observed to follow 2nd order kinetics for all photocatalysts at all temperatures. Band gap studies confirmed a lower energy than that of pure ZnO …

Learning To Detect Pedestrians By Watching Videos, Andrew Y. Chen

Theses and Dissertations

The field of deep learning has experienced a resurgence in the recent years, particularly resulting with the advent of AlexNet. Supervised learning is currently the most common and practical machine learning method. The struggle with employing supervised learning to approach problems is that it requires training data. Sufficient training data is correlated with performance for deep learning models. The issue is that preparing the training data can be a tedious and labor intensive task, especially on a large scale. The purpose of this paper is to determine how efficient a machine can learn when trained on automatically annotated data. The …

Viability Of Wetland Crops For Use In Treatment Wetlands: Nitrogen Removal From Water And Production Of Food, Andrew Denson Corder

Theses and Dissertations

Treatment wetlands are used to treat wastewater from a variety of sources, but their functionality depends on the macrophytes present therein. To better understand the viability of wetland macrophytes both as sources of food and as agents of nitrogen removal from wastewater, this study quantified plant growth, food production, and nitrogen removal capacity of three common wetland crops as well as three locally dominant graminoid species in a variety of relevant ecological contexts. All six plant species and a control were grown over a ten-week period in three related experiments: (1) under three moisture regimes, (2) with or without competition …

Comparison Of Rl Algorithms For Learning To Learn Problems, Adolfo Gonzalez Iii

Theses and Dissertations

Machine learning has been applied to many different problems successfully due to the expressiveness of neural networks and simplicity of first order optimization algorithms. The latter being a vital piece needed for training large neural networks efficiently. Many of these algorithms were produced with behavior produced by experiments and intuition. An interesting question that comes to mind is that rather than observing and then designing algorithms with beneficial behaviors, can these algorithms be learned through a reinforcement learning by modeling optimization as a game. This paper explores several reinforcement learning algorithms which are applied to learn policies suited for optimization.

A Landscape-Scaled And Community Ecology Approach To Wildlife Corridor Design In South Texas, James A. Stilley

Theses and Dissertations

A formidable challenge in landscape ecology is developing a sound resolution to mitigate the impacts of habitat fragmentation and restore connectivity to a degraded landscape. The problem is worldwide landscapes are becoming primarily anthropogenic and areas set aside for wildlife are small and isolated. Researchers’ have developed the concept of the wildlife corridor to mediate this situation but a proper methodology to implement this concept is still in its infancy. This study aims to uncover a quantitative and repeatable wildlife corridor design methodology based on the least cost analysis strategy with both a singular focal taxa approach and a comprehensive …

A Sinking Feeling: The Fate Of Concrete Pyramids Deployed In Artificial Reefs In The Texas Gulf Of Mexico, Cameron J. Moody

Theses and Dissertations

The deployment of 2,611 concrete pyramids in Texas gulf waters represents a significant undertaking. In collaboration with Texas Parks and Wildlife, bathymetric sidescan data was collected at three reefs hit by Hurricane Harvey from 2017 to 2019. All reefs lost significant pyramid height between 2017 and 2019. The pyramids demonstrated greater subsidence in the year when Harvey occurred and minimal subsidence the following year. Pyramids that moved outside the reefs were due to hurricane forces and shrimp trawl activity. Pyramids that remained inside the reef remained at their deployment location for two reefs. The pyramids remaining in the third reef …

Identifying The N Sources For Black Mangrove (Avicennia Germinans) In A South Texas Mangrove Forest, Ashley Elizabeth Murphy

Theses and Dissertations

Black mangrove (Avicennia germinans) in south Texas provide ecosystem services and benefits to humans including: habitat for wildlife, prevention of coastline erosion, and mitigation of natural disasters. One step to preserve their ecological functions is to identify and protect the source of their nitrogen (N). Nitrogen stable isotopes were sampled for one year beginning August 2018 and used as tracers to identify how mangroves obtain N. Total N in (A. germinans) and associated (Batis maritima) (plants) (2.1%) was more abundant than in cyanobacteria (0.6%) and sediment (0.1%). Plant d15N signatures (5.52‰) were more similar to sediment (5.21‰) than cyanobacteria (1.98‰), …

Dna Barcoding Reveals Unexpected Diversity In Octocorallia In The Northwestern Gulf Of Mexico, Chelsea L. Pavliska

Theses and Dissertations

Coral reefs are an integral tier of marine ecosystems. They provide habitat and foraging opportunities for many ecologically and economically important fishes. Protection of coral reef biodiversity and connectivity is imperative to the continued health and sustainability of marine fisheries. Mesophotic reefs, such as those found in the northwest Gulf of Mexico, have unique coral communities because of the limited light penetration at mesophotic depths (30 – 150m). Because there is limited knowledge in regards to the biodiversity of coral reefs of the northwestern Gulf of Mexico (GOM), particularly the South Texas Banks (STBs), thesis work presented here aims to …

Detecting Phone-Related Pedestrian Behavior Using A Two-Branch Convolutional Neural Network, Humberto Saenz

Theses and Dissertations

With the wide use of smart phones, distraction has become a major safety concern to roadway users. The distracted phone-use behaviors among pedestrians, like Texting, Game Playing and Phone Calls, have caused increasing fatalities and serious injuries. With the increasing usage of driver monitor systems on intelligent vehicles, distracted driver behaviors can be efficiently detected and warned. However, the research of phone-related distracted behavior by pedestrians has not been systemically studied. It is desired to improve both the driving and pedestrian safety by automatically discovering the phone-related pedestrian distracted behaviors. In this thesis, we propose a new computer vision-based method …

Investigation Of Constant Volume And Constant Flux Initial Conditions On Bidensity Particle-Laden Slurries On An Incline, Dominic Diaz, Jessica Bojorque, Joshua Crasto, Margaret Koulikov, Tameez Lati, Aviva Prins, Andrew Shapiro, Clover Ye, David Arnold, Michael R. Lindstrom

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

Particle-laden slurries are pervasive in both natural and industrial settings, whenever particles are suspended or transported in a fluid. Previous literature has investigated the case of a single species of negatively buoyant particles suspended in a viscous fluid. On an incline, three distinct regimes emerge depending on the particle concentration and inclination angle: settled (where particles settle and there is a pure fluid front), well-mixed (where particle concentration is constant throughout), and ridged (where a particle-rich ridge leads the flow). Recently, the same three regimes were also found for constant volume two species bidensity slurries. We extend the literature on …

Raman Investigations On Gamma Irradiated Ipp-Vgcnf Nanocomposites: The Polymer's Tale, Dorina M. Chipara, Corina Secu, Karen Lozano, Mihail Secu, Mircea Chipara

Physics and Astronomy Faculty Publications and Presentations

Raman investigations on nanocomposites obtained by loading various amounts of vapor grown carbon nanofibers within an isotactic polypropylene matrix, and gamma irradiated in air, at various integral doses ranging between 0 and 27 kGy, are reported. The analysis is focused on the polymer's answers as revealed by Raman spectroscopy and investigate in detail the effect of ionizing radiation on the position of the Raman line originating from the polymer. The as-obtained data are correlated to the elastic features of the nanocomposites. A competition between gamma irradiation and loading by carbon nanofiber, resulting in the stretching of the polymeric matrix …

High-Order Rogue Waves Of A Long-Wave–Short-Wave Model Of Newell Type, Jungchao Chen, Liangyuan Chen, Bao-Feng Feng, Ken-Ichi Maruno

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

The long-wave–short-wave (LWSW) model of Newell type is an integrable model describing the interaction between the gravity wave (long wave) and the capillary wave (short wave) for the surface wave of deep water under certain resonance conditions. In the present paper, we are concerned with rogue-wave solutions to the LWSW model of Newell type. By combining the Hirota’s bilinear method and the KP hierarchy reduction, we construct its general rational solution expressed by the determinant. It is found that the fundamental rogue wave for the short wave can be classified into three different patterns: bright, intermediate, and dark states, whereas …

Mitogenomic Phylogenetic Analyses Of Leptogorgia Virgulata And Leptogorgia Hebes (Anthozoa: Octocorallia) From The Gulf Of Mexico Provides Insight On Gorgoniidae Divergence Between Pacific And Atlantic Lineages, Samantha Silvestri, Diego F. Figueroa, David Hicks, Nicole J. Figueroa

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

The use of genetics in recent years has brought to light the need to reevaluate the classification of many gorgonian octocorals. This study focuses on two Leptogorgia species—Leptogorgia virgulata and Leptogorgia hebes—from the northwestern Gulf of Mexico (GOM). We target complete mitochondrial genomes and mtMutS sequences, and integrate this data with previous genetic research of gorgonian corals to resolve phylogenetic relationships and estimate divergence times. This study contributes the first complete mitochondrial genomes for L. ptogorgia virgulata and L. hebes. Our resulting phylogenies stress the need to redefine the taxonomy of the genus Leptogorgia in its entirety. The fossil-calibrated divergence …

Novel Silica Filled Deep Eutectic Solvent Based Nanofluids For Energy Transportation, Changhui Liu, Hui Fang, Xinjian Liu, Ben Xu, Zhonghao Rao

Chemistry Faculty Publications and Presentations

Liquid range of nanofluids is a crucial parameter as it intensively determines their application temperature scope. Meanwhile, improved thermal conductivity and stability are of great significances and comprise the main fundamental research topics of nanofluids. In this work, 2- butoxy-3,4-dihydropyran (DP), produced from a convenient one-pot three-component reaction in water, was employed as dual lipophilic brusher and metal nanoparticle anchor. It was found that DP was able to enhance the dispersing ability and thermal conductivity of SiO2 nanoparticle filled deep eutectic solvent (DES) based nanofluids simultaneously. The key to the success of this protocol mainly relies on the electrophilic property …

The Complete Mitochondrial Genome Of Tanacetipathes Thamnea Warner, 1981 (Antipatharia: Myriopathidae), Diego F. Figueroa, David Hicks, Nicole J. Figueroa

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

Specimens of the black coral Tanacetipathes thamnea were collected from the Northwestern Gulf of Mexico. The complete mitochondrial genome of one of these specimens was obtained from genomic DNA by next-generation sequencing technology on the Illumina HiSeq 2500. Only three species of black corals have a completely sequenced mitochondrial genome. These were used to reconstruct the phylogeny for the order Antipatharia. The mitochondrial genome of T. thamnea is 17,712 base pairs and contains 13 protein-coding genes, 2 ribosomal RNAs, and 2 transfer RNAs in the following order: 16s RNA, COX3, COX1 (with intron), ND4L, COX2, ND4, …

Tests Of General Relativity With The Binary Black Hole Signals From The Ligo-Virgo Catalog Gwtc-1, B. P. Abbott, S. Mukherjee

Physics and Astronomy Faculty Publications and Presentations

The detection of gravitational waves by Advanced LIGO and Advanced Virgo provides an opportunity to test general relativity in a regime that is inaccessible to traditional astronomical observations and laboratory tests. We present four tests of the consistency of the data with binary black hole gravitational waveforms predicted by general relativity. One test subtracts the best-fit waveform from the data and checks the consistency of the residual with detector noise. The second test checks the consistency of the low- and high-frequency parts of the observed signals. The third test checks that phenomenological deviations introduced in the waveform model (including in …

Non-Invasive Methods For Measuring And Monitoring Stress Physiology In Imperiled Amphibians, Edward J. Narayan, Zachery R. Forsburg, Drew R. Davis, Caitlin R. Gabor

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

Global climate change is negatively impacting global biodiversity and ectothermic vertebrates, with amphibians being the most imperiled vertebrate taxa. Increased mean global atmospheric temperatures, high rates of habitat degradation, and exposure to infectious diseases, such as chytridiomycosis, have contributed to population declines and extinctions of rare and endangered amphibian species. Field-based monitoring of physiological endocrine traits can help determine the sub-lethal effects of environmental stressors and provide early alerts when populations are chronically stressed. Recent advances in amphibian stress endocrinology include the development and use of non-invasive methods to quantify the glucocorticoid, or stress biomarker, corticosterone. Non-invasive methods, such as …

Water‐Borne And Plasma Corticosterone Are Not Correlated In Spotted Salamanders, Alice R. Millikin, Sarah K. Woodley, Drew R. Davis, Ignacio T. Moore, James T. Anderson

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

Water‐borne hormone measurement is a noninvasive method suitable for amphibians of all sizes that are otherwise difficult to sample. For this method, containment‐water is assayed for hormones released by the animal. Originally developed in fish, the method has expanded to amphibians, but requires additional species‐specific validations. We wanted to determine physiological relevance of water‐borne corticosterone in spotted salamanders (Ambystoma maculatum) by comparing concentrations to those taken using established corticosterone sampling methods, such as plasma. Using a mixture of field and laboratory studies, we compared water‐borne corticosterone levels to other traditional methods of sampling corticosterone for spotted salamander larvae, metamorphs, and …

Investigations Of Aerobic Methane Oxidation In Two Marine Seep Environments: Part 1—Chemical Kinetics, Eric W. Chan, Allan M. Shiller, Dongjoo J. Joung, Eleanor C. Arrington, David L. Valentine, Molly C. Redmond, John A. Breier, Scott A. Socolofsky, John D. Kessler

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

Microbial aerobic oxidation is known to be a significant sink of marine methane (CH4), contributing to the relatively minor atmospheric release of this greenhouse gas over vast stretches of the ocean. However, the chemical kinetics of aerobic CH4 oxidation are not well established, making it difficult to predict and assess the extent that CH4 is oxidized in seawater following seafloor release. Here we investigate the kinetics of aerobic CH4 oxidation using mesocosm incubations of fresh seawater samples collected from seep fields in Hudson Canyon, U.S. Atlantic Margin and MC118, Gulf of Mexico to gain a fundamental chemical understanding of this …

Realistic Sensitivity Curves For Pulsar Timing Arrays, ‪Jeffrey S. Hazboun, Joseph D. Romano, Tristan L. Smith

Physics and Astronomy Faculty Publications and Presentations

We construct realistic sensitivity curves for pulsar timing array searches for gravitational waves, incorporating both red and white noise contributions to individual pulsar noise spectra, and the effect of fitting to a pulsar timing model. We demonstrate the method on both simulated pulsars and a realistic array consisting of a subset of NANOGrav pulsars used in recent analyses. A comparison between the results presented here and measured upper limit curves from actual analyses shows agreement to tens of percent. The resulting sensitivity curves can be used to assess the detectability of predicted gravitational-wave signals in the nanohertz frequency band in …

Magnetic Field Effect In The Fine-Structure Constant And Electron Dynamical Mass, Efrain J. Ferrer, A. Sanchez

Physics and Astronomy Faculty Publications and Presentations

We investigate the effect of an applied constant and uniform magnetic field in the fine-structure constant of massive and massless QED. In massive QED, it is shown that a strong magnetic field removes the so called Landau pole and that the fine-structure constant becomes anisotropic having different values along and transverse to the field direction. Contrary to other results in the literature, we find that the anisotropic fine-structure constant always decreases with the field. We also study the effect of the running of the coupling constant with the magnetic field on the electron mass. We find that in both cases …

Investigations Of Aerobic Methane Oxidation In Two Marine Seep Environments: Part 2—Isotopic Kinetics, Eric W. Chan, Allan M. Shiller, Dongjoo J. Joung, Eleanor C. Arrington, David L. Valentine, Molly C. Redmond, John A. Breier, Scott A. Socolofsky, John D. Kessler

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

During aerobic oxidation of methane (CH4) in seawater, a process which mitigates atmospheric emissions, the 12C‐isotopologue reacts with a slightly greater rate constant than the 13C‐isotopologue, leaving the residual CH4 isotopically fractionated. Prior studies have attempted to exploit this systematic isotopic fractionation from methane oxidation to quantify the extent that a CH4 pool has been oxidized in seawater. However, cultivation‐based studies have suggested that isotopic fractionation fundamentally changes as a microbial population blooms in response to an influx of reactive substrates. Using a systematic mesocosm incubation study with recently collected seawater, here we investigate the fundamental isotopic kinetics of aerobic …

Trust And Influence In The Gulf Of Mexico’S Fishery Public Management Network, Anthony Lima, Dongkyu Kim, Andrew M. Song, Gordon M. Hickey, Owen Temby

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

Sustainable fishery management is a complex multi-sectoral challenge requiring substantial interagency coordination, collaboration, and knowledge sharing. While scholars of public management network theory and natural resource management have identified trust as one of the key ideational network properties that facilitates such interaction, relatively few studies have operationalized and measured the multiple dimensions of trust and their influence on collaboration. This article presents the results of an exploratory study examining the Gulf of Mexico fishery management network comprised of more than 30 stakeholder organizations. Using an empirically validated survey instrument, the distribution of four types of trust, three gradations of influence, …

Increasing Impacts Of Extreme Droughts On Vegetation Productivity Under Climate Change, Chonggang Xu, Nate G. Mcdowell, Rosie A. Fisher, Liang Wei, Sanna Sevanto, Bradley O. Christoffersen, Engsheng Weng, Richard S. Middleton

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

Terrestrial gross primary production (GPP) is the basis of vegetation growth and food production globally1 and plays a critical role in regulating atmospheric CO2 through its impact on ecosystem carbon balance. Even though higher CO2 concentrations in future decades can increase GPP2, low soil water availability, heat stress and disturbances associated with droughts could reduce the benefits of such CO2 fertilization. Here we analysed outputs of 13 Earth system models to show an increasingly stronger impact on GPP by extreme droughts than by mild and moderate droughts over the twenty-first century. Due to a dramatic increase in …

Remote Sensing Of The Terrestrial Carbon Cycle: A Review Of Advances Over 50 Years, Jingfeng Xiao, Frederic Chevallier, Cecile Gomez, Luis Guanter, Jeffrey A. Hicke, Alfredo R. Huete, Kazuhito Ichii, Wenjian Ni, Yong Pang, Abdullah F. Rahman

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

Highlights

• We review 50 years of history and advances in remote sensing of C fluxes and stocks

• We present an overview of terrestrial C cycle, remote sensing, and key milestones

• We review remote sensing platforms/sensors, data, methods, findings, and challenges

• We also discuss the uncertainty and validation of the C flux and stock estimates

• A forward-looking perspective and insights for future research are provided

Abstract

Quantifying ecosystem carbon fluxes and stocks is essential for better understanding the global carbon cycle and improving projections of the carbon-climate feedbacks. Remote sensing has played a vital role in this endeavor during the last …

Experimental Demonstration Of Deterministic Chaos In A Waste Oil Biodiesel Semi-Industrial Furnace Combustion System, Shengyang Gao, Fashe Li, Qintai Xiao, Jianxin Xu, Huage Wang, Hua Wang

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

In this paper, the nonlinear dynamic characteristics of the oxygen-enriched combustion of waste oil biodiesel in semi-industrial furnaces were tested by the power spectrum, phase space reconstruction, the largest Lyapunov exponents, and the 0-1 test method. To express the influences of the system parameters, experiments were carried out under different oxygen content conditions (21%, 25%, 28%, 31%, and 33%). Higher oxygen enrichment degrees contribute to finer combustion sufficiency, which produces flames with high luminance. Flame luminance and temperature can be represented by different gray scale values of flame images. The chaotic characteristics of gray scale time series under different oxygen …

Search For Gravitational-Wave Signals Associated With Gamma-Ray Bursts During The Second Observing Run Of Advanced Ligo And Advanced Virgo, B. P. Abbott, R. Abbott, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, K. E. Ramirez, Satzhan Sitmukhambetov, Robert Stone, D. Tuyenbayev, W. H. Wang

Physics and Astronomy Faculty Publications and Presentations

We present the results of targeted searches for gravitational-wave transients associated with gamma-ray bursts during the second observing run of Advanced LIGO and Advanced Virgo, which took place from 2016 November to 2017 August. We have analyzed 98 gamma-ray bursts using an unmodeled search method that searches for generic transient gravitational waves and 42 with a modeled search method that targets compact-binary mergers as progenitors of short gamma-ray bursts. Both methods clearly detect the previously reported binary merger signal GW170817, with p-values of z ≤ 1. We estimate 0.07–1.80 joint detections with Fermi-GBM per year for the 2019–20 …

Biochar Enhances Nitrous Oxide Reduction In Acidic But Not In Near-Neutral Ph Soil, Engil Isadora Pujol Pereira, Jerome Lechot, Rafaela Feola Conz, Abmael Da Silva Cardoso, Johan Six

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

We quantified nitrous oxide (N2O) fluxes and total denitrification (N2O + N2) in an acidic (Ferralsol) and a near-neutral pH soil (Cambisol) to determine whether biochar’s alkalinization effect could be the mechanism inducing potential reductions in N2O fluxes. In Ferralsol, decreases in N2O emissions and in the N2O to N2O + N2 ratio were observed in both biochar and lime treatments. In Cambisol, neither biochar nor lime decreased N2O emissions, despite significantly increasing soil pH. The abundance and community structure of nosZ gene-bearing microorganisms indicated that gene abundances did not explain biochar effects, but a higher diversity of nosZ gene-bearing …

Samarium-Activated La2hf2o7 Nanoparticles As Multifunctional Phosphors, Santosh K. Gupta, Maya Abdou, Jose P. Zuniga, Alexander A. Puretzky, Yuanbing Mao

Chemistry Faculty Publications and Presentations

Recent developments in the field of designing novel nanostructures with various functionalities have pushed the scientific world to design and develop high-quality nanomaterials with multifunctional applications. Here, we propose a new kind of doped metal oxide pyrochlore nanostructure for solid-state phosphor, X-ray scintillator, and optical thermometry. The developed samarium-activated La2Hf2O7 (LHOS) nanoparticles (NPs) emit a narrow and stable red emission with lower color temperature and adequate critical distance under near-UV and X-ray excitations. When the LHOS NPs are exposed to an energetic X-ray beam, the Sm3+ ions situated at the symmetric environment get excited along with those located at the …

Spatial And Seasonal Differences In The Top Predators Of Easter Island: Essential Data For Implementing The New Rapa Nui Multiple‐Uses Marine Protected Area, Naiti A. Morales, Erin E. Easton, Alan M. Friedlander, Euan S. Harvey, Rodrigo Garcia, Carlos F. Gaymer

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

1. Reef fishes are an important component of marine biodiversity, and changes in the composition of the assemblage structure may indicate ecological, climatic, or anthropogenic disturbances. To examine spatial differences in the reef fish assemblage structure around Easter Island, eight sites were sampled during autumn and summer 2016–2017 with baited remote underwater video systems.
2. To determine seasonal changes, quarterly (seasonal) sampling was conducted at five of those eight sites. Fifteen pelagic species of fishes were recorded during this study, some of which have not previously been recorded in scuba surveys, including the Galapagos shark (Carcharhinus galapagensis, Snodgrass & Heller, …