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Improved Whitecap Quantification and Prediction Using Shipboard Remote Sensing and Machine Learning
No full textWhitecaps generated by wave breaking and air entrainment can be classified as active (stage A) or residual (stage B). Discrimination and measurement of each stage individually are essential for accurate parameterization of air-sea interaction processes, but conventional methods used for separation in visible images are subjective. This study provides a novel method to identify whitecap stages based on visible imagery using particle image velocimetry (PIV). A linear relationship was established between the lifetime of stage A and the timescale of averaged velocity. This novel method characterizes stage A whitecap lifetime using whitecap velocity and provides an objective approach to separate whitecap stages.
To estimate active whitecap fraction, we introduced a pipeline for active whitecap fraction measurement. In this pipeline, a new horizon detection method is developed to stabilize and rectify images and a deep learning model based on U-Net is trained and validated to identify and extract active whitecaps. The model is applied to 48 hours of video footage collected during a cruise in Gulf of Mexico. It is determined that, as a function of wind speed, active whitecap fraction has significant variability and disparity compared to previous research. This finding indicates that secondary factors should be considered for accurate whitecap parameterization. This is explored using principal component analyses and random forest, which indicate sea surface temperature, swell and wave age are important to active whitecap fraction. The precise impact of sea surface temperature is further explored using analyses of variance (ANOVA), which suggest it has a positive correlation with active whitecap fraction.
The decaying stage B foam with significant variability has been found to contribute 1.5 to 40 times more to total whitecap fraction than stage A foam. In this study, we present a novel model that describes the relationship between whitecap fraction and the evolution of whitecap area, providing a method to quantify the whitecap lifetime scale. The same data from a Gulf of Mexico cruise is processed using this method. The stage B lifetime scale shows weak positive correlation with active whitecap fraction and no correlation with sea surface temperature and wind speed
Motion Control Analysis of Hydrofoil-Based Autonomous Surface Vehicle: An Integrated Approach Utilizing Moving-Mass-Actuated Stabilizer and Variable RPM Propeller Modeled with Computational Fluid Dynamics and Auto-Control Algorithm
No full textHydrofoil-based Surface Vehicles (HSVs) have garnered significant attention for their potential to achieve high speeds, low hydrodynamic resistance, and reduced energy consumption. This efficiency is primarily due to the vehicle���s hull being elevated above the waterline, leaving only the hydrofoils and propeller submerged to generate the necessary lift force to counterbalance the vehicle���s weight at operational speeds. This study aims to extend these advantages by developing an autonomous control system, thereby enhancing the operational capabilities of these vehicles.
This dissertation dedicates to overcoming the inherent stability challenges in the in-house developed hydrofoil-based Autonomous Surface Vehicle (HASV). This battery-powered HASV leverages hydrofoil to lift its superstructure above the water, significantly decreasing drag and improving efficiency at cruising speeds. However, the design, which incorporates a single mast connecting the superstructure to the substructure, introduces notable stability issues. These challenges primarily arise from nonlinear flow loading on the hydrofoil substructure and external environmental factors such as ocean waves and currents. This complexity necessitates the development of an effective control system.
In response to these challenges, the study introduces an innovative control system utilizing the Proportional-Integral-Derivative (PID) algorithm to regulate the HASV���s pitch, roll, and heave stability. It includes a novel moving-mass-actuated (MMA) stabilizer in conjunction with an adjustable revolutions-per-minute (rpm) propeller. The MMA stabilizer enables dynamic adjustment of the HASV���s center of gravity, enhancing control over pitch and roll movements. Simultaneously, the propeller���s rpm is continuously modulated to manage thrust, thereby adjusting the lift force generated by the HASV substructure, which is crucial for controlling heave motion stability.
Previous research on HASV stability control primarily relied on either physical model testing or mathematical modeling. While physical model testing is comprehensive, it is often prohibitively expensive and time-consuming. In contrast, mathematical models, though efficient, require significant simplifications, frequently failing to fully capture complex physical processes, especially those with strong free surface effects. Given the HASV���s limited stability and pronounced free surface effects, there is an urgent need for a more effective and practical approach to investigate and optimize the PID control system. Addressing this need, the study proposes a more accurate Unsteady Reynolds-Averaged Navier-Stokes (URANS) CFD-based control investigation approach. This approach integrates a PID controller into the URANS CFD model, combining the detailed analysis capabilities of CFD with the precision of PID control. This integration ensures that the performance of the proposed control system can be precisely investigated and optimized under different diverse operational scenarios.
This study first starts with the CFD-based hydrodynamic performance analysis of a 2D dual hydrofoils with different configuration and generated a dataset, the dataset is then used to train an Artificial Neural Network (ANN) in order to use the ANN to interpolate within the interesting range and generate a finer resolution results. This analysis helps to have a basic understanding of how the wing and tail can interact with each other and laying the ground for the design of the submerged portion (substructure) of the HASV. Later, this study continues with a scaled-down experimental setup and procedure designed to test the hydrodynamic characteristics of the HASV���s substructure. This experimental study resulted in an understanding of the drag and lift behavior of the substructure, which is be used in the validation of the 3D CFD model. Then, this study continues to use the validated 3D CFD model as a tool to apply the CFD-based control investigation approach, mentioned above, to optimize the performance of the PID controller for regulating the HASV���s roll, pitch and heave motion. Then the effectiveness of the optimized control system on these three DOFs is tested using the CFD-based control investigation approach under different loading scenarios (calm water and waves)
Advancing Iron Catalyzed Three-Component Cross-Coupling Reactions
No full textTransition metal���catalyzed cross-coupling reactions are some of the most widely used methods in chemical synthesis. Notable advantages of iron as a potentially cheaper, more abundant, and a less toxic transition metal catalyst have drawn the interest of our lab, in particular to explore the mechanism of action in three-component radical cross-couplings. In the first project, we explored the difunctionalization of unactivated olefins with alkyl halides and Grignard reagents. The reaction tolerates a wide range of sp^2 hybridized nucleophiles, alkyl halides, and unactivated olefins bearing a diverse range of functional groups.
Our second work highlights iron���s practical application in more elaborate multicomponent cross-couplings including formation and trapping of ��-boryl radicals and allyl alkyl halides for practical synthesis of cyclic fluorous compounds. Incorporating fluorine into drug scaffolds remains of utmost importance in medicinal chemistry since it generally increases lipophilicity, stability, and overall lifetime, and ~20% of drugs on the market contain at least one C-F bond. In that vein, pinacol boronate esters and boronic acids are excellent building blocks due to their reaction efficiency, low cost, and ability to be transformed into many other desired functional groups.
The final research focus is on using a mechanistic-driven approach towards designing new chiral organoiron catalytic species capable of controlling the C-C bond formation with diverse C-centered radicals. To date, there are only three examples of enantioselective iron-catalyzed cross-coupling reactions, and all are limited to the union of only two components. We reported a practical and simple protocol that uses commercially available and inexpensive iron salts in combination with chiral bisphosphine ligands to enable the regio- and enantioselective (up to 91:9) multicomponent cross-coupling of vinyl boronates, (fluoro)alkyl halides, and Grignard reagents. Preliminary mechanistic studies are consistent with rapid formation of ��-boryl radical followed by reversible radical addition to mono-aryl bisphosphine-Fe(II) and subsequent enantioselective inner-sphere reductive elimination. Overall, my research is expected to expand the field of asymmetric iron cross-couplings and have broad implications towards the synthesis of bioactive compounds via the use of alkenes to translocate alkyl radicals, modify their steric and electronic properties, and induce stereocontrol
An Evaluation of Alternatives for Updating Base Acres in the 2024 Farm Bill
No full textGiven that the income-support provisions in the farm bill have been decoupled from production for more than two decades, base acres are no longer reflective of planted acres in the United States. Three alternatives are currently being discussed to better align base acres with current plantings in the next farm bill: 1) a reallocation of bases to current plantings, 2) a forced update to current plantings, and 3) a rolling average of the plantings from the previous two years. There undoubtedly will be winners and losers across individual operations, crops, and regions. Knowing who will be impacted would enable Congress to make more informed decisions regarding base updates. To comprehensively evaluate the alternatives, this study undertook a farm-level and national analysis.
The farm-level analysis was implemented by collecting data from four representative farms maintained by the Agricultural and Food Policy Center at Texas A&M University. For each farm, base acres were calculated for the three alternatives, and stochastic simulation was used to determine a five-year forecast of average government payments, ending cash, and ending real net worth. The national analysis was conducted by collecting public data from the Department of Agriculture���s Farm Service Agency for nine covered commodities and calculating new base acres per county to determine absolute gains and losses. The absolute change per crop per county was totaled to determine the deviations between the current baseline and each scenario being analyzed.
The results from the farm-level and national analysis indicate a wide variety of impacts on individual farms, crops, and regions. While maintaining current base acres might be the optimal solution for one location or commodity, it is apparent that the same scenario would be less preferred by others. One universal option (e.g., to reallocate base acres) might not be the best solution; in fact, allowing producers to choose amongst several options might be the best route for baseline modification in the next farm bill, recognizing that approach will also cost the most
Teacher Motivations for Field Trips to Small Museums
No full textThis study explored what components are most valued by teachers during the planning phase of field trips to small museums. It identified teachers' motivations and constraints when planning a field trip to a small museum. In addition, it examined the influence of motivations and constraints on the likelihood of teachers taking a field trip and teachers��� willingness to put in effort to take a field trip after the planning phase. Past research on teacher motivations for field trips, however, reveals a need to improve in the area of small museums. Small museums are significant contributors to society by providing local access to education, creating job opportunities, promoting sustainability, and more. This study sought to find teachers' motives and constraints during field trip planning and the intention of taking a field trip after planning through survey data collected from teachers ranging from kindergarten to twelfth grade. The data analyzed were grouped into motives, constraints, likelihood, and willingness. The findings offer insight to small museums to make the necessary investments in school field trips that may increase revenue, enhance community engagement, and create better educational experiences
Target Identification Using Single Cell RNA-Seq: Algorithms and Applications
No full textTarget identification is a crucial step in the drug development process, significantly affecting the success rate and efficiency of bringing new therapies to market. Recent advancements in single-cell RNA sequencing and computational tools have accelerated the identification and validation of therapeutic targets by enabling a deeper understanding of disease mechanisms at the cellular level. However, challenges such as inadequate understanding of the molecular basis of certain diseases and limitations in current single-cell data analysis methods, particularly in capturing gene regulatory relationships, continue to hinder the full exploitation of these technologies in precision medicine.
To this end, we aim to enhance target identification in scRNA-seq, crucial for unraveling cellular differentiation and disease mechanisms. Firstly, we develop ���scInTime���, a computational method that capitalizes on single-cell trajectory data and gene regulatory networks to accurately identify master regulators of cellular differentiation. This algorithm aims to overcome the existing challenges in mapping cell fate decisions, a critical step in advancing personalized medicine. Secondly, we propose to undertake an integrated scRNA-seq data analysis to investigate the association between pyroptosis and the severity of COVID-19. This research is expected to shed light on the immune response to SARS-CoV-2 and identify potential targets for therapeutic intervention. By focusing on the mechanisms underlying severe COVID-19 cases, we anticipate contributing to the global effort in combating the pandemic. Thirdly, we address metabolic diseases, specifically investigating the role of hepatocyte adenosine kinase in fat deposition and liver inflammation. Here, we aim to elucidate the molecular pathways that lead to excessive fat storage and inflammation in the liver, offering targets for the treatment of metabolic syndromes. Finally, we conduct a sex-based study on the role of RSPO3 in estrogen-mediated sex differences. Understanding the molecular bases of sex differences in diseases is critical for the development of gender-specific therapies and this study will contribute to that knowledge base.
Overall, our goal is to leverage scRNA-seq for precise target identification, addressing significant gaps in the understanding of cellular differentiation and disease. This thesis is designed to set the stage for a series of investigations that will collectively advance our knowledge in the field and lead to novel therapeutic strategies
Economic Indicators of the College Station - Bryan MSA, January 2025
No full textThe Business-Cycle Index decreased 0.2% from October 2024 to November 2024.1 The local unemployment rate increased to 3.3% in November 2024 compared to 3.2% in October. Local nonfarm employment increased by 0.04% from October 2024 to November 2024. Inflation-adjusted taxable sales decreased by 1% from October 2024 to November 2024. For 2023, the newly released Real Gross Domestic Product (GDP) for the College Station-Bryan MSA grew at an annualized rate of 3.9%, more than both the state of Texas (at 3.8%) and the entire U.S.(at 2.3%) over the same period
SMC-M1 Connectivity and Motor Sequence Learning: A TMS Study
No full textWe experience various types of motor learning throughout our lives. As children, we learned to walk unconsciously. As we grow older, we continue to learn skills like sports or musical instruments. In this study, the primary motor cortex (M1) and the supplementary motor complex (SMC), which are brain regions involved in motor sequence learning but where many aspects still remain unclear, were mainly investigated, and the connectivity of these two regions was measured using the paired-pulse transcranial magnetic stimulation (ppTMS) technique. In Experiment I, sixty-three right-handed undergraduate students participated. Conditioning stimulus (CS) was administered at SMC (i.e., 4 cm anterior to Cz), and test stimulus (TS) was applied at M1. As a result, consistent with the previous ppTMS studies, a facilitatory influence was observed between SMC and M1. In Experiment II, fifty-one right-handed undergraduate students participated. After measuring baseline SMC-M1 connectivity in the same way as in Experiment I, individuals practiced one of three motor sequential tasks (i.e., implicit, explicit, or random sequence task). After practice, ppTMS as post-training stimulation was administered in the same way as the baseline stimulation to investigate the changes in the connectivity between SMC and M1. As a result, it was found that the facilitatory influence decreased after the explicit sequence task that involved motor chunking. This may be because SMC plays a role in motor chunking. In Experiment III, instead of a motor task, intermittent theta-burst stimulation (iTBS) was administered at SMC between two ppTMS sessions, and the connectivity changes were investigated. Similar to the influence of the explicit sequence task in Experiment II, the facilitatory influence decreased in the iTBS group. Although the mechanisms are different from each other, iTBS appears to induce post-synaptic plasticity in the cortico-basal ganglia-thalamic network. After post-stimulation of ppTMS, participants performed the explicit sequence task used in Experiment II twice (i.e., practice and retention test) to reveal the effect of iTBS on motor sequence learning. In the iTBS group, the offline improvement was disturbed at concatenation points compared to the Rest group. In the future, follow-up research that dissociates motor chunking conditions using neuroimaging techniques seems necessary
Allocation of Peptidoglycan Resources Between the Rod System and Class-A Penicillin-Binding Proteins in Myxococcus xanthus
No full textPeptidoglycan (PG) is a polymer scaffolding surrounding the cell membrane of bacteria and is key to survival as it aids in preserving cell structure and protects against harmful stresses. It is composed of alternating N-acetylglucosamine and N-acetylmuramic acid strands that are crosslinked through peptide chains. The synthesis of PG is a highly dynamic and tightly regulated process, spanning across the cytoplasm, inner membrane, and periplasm in gram-negative bacteria. PG synthesis is vital for cell survival and remodeling of the sacculus is required during cell elongation and division as well as during PG repair. PG synthesis has been heavily studied, however, it is still unknown how the allocation of PG precursors are portioned between the two PG synthase systems of the class-A penicillin-binding proteins and the Rod system. Here we take advantage of the monomer-dimer characteristic of the phospho-MurNAc-pentapeptide translocase protein, MraY, as a proxy for PG precursor usage of PG synthases. Using single particle tracking photoactivatable localization microscopy, we show that the Rod system is the main synthase system active in vegetative growth while aPBP���s are responsible for PG repair. This study aims to further understand the properties of PG synthesis and how the cell divides its resources during vegetative growth and repair
Ira Greenbaum field notebook: GK4001-GK4500.pdf
No full textBound book, each page corresponds to a karyotype slide data.Data pages for GK4001-GK4500 corresponding to unique identifiers of specimens/samples examined for biological research. Specimens are primarily housed at Texas A&M University; Biodiverstiy Research and Teaching Collection