Texas A&M University – Corpus Christi
Texas A&M University - Corpus Christi: DSpace RepositoryNot a member yet
36255 research outputs found
Sort by
Interaction between nitric oxide and serotonin in the formation of long-term sensitization in the mollusk Aplysia
No full textDepartment of Life Sciences, College of ScienceLearning is a process by which all animals modify their behaviors to ensure increased fitness (Nordell 2021). Long-term sensitization (LTS) in the mollusk Aplysia is a well-known example of learning in which defensive responses, such as the tail-siphon withdrawal reflex (TSWR), are heightened for prolonged periods following repeated exposure to noxious stimuli (i.e., aversive training; Byrne and Hawkins 2015). The neurotransmitter serotonin (5-HT) mediates LTS formation in Aplysia (Byrne and Hawkins 2015). In vivo, 5-HT exposure alone can induce LTS (Levenson et al. 1999). However, recent findings indicate that the neurotransmitter nitric oxide (NO) is also necessary for LTS formation (Farruggella et al. 2019). Therefore, in this study, an experiment was designed to position NO on the 5-HT-mediated biochemical pathway
Encrypted observer-based control for linear continuous-time systems
No full textThis paper is concerned with the stability analysis of encrypted observer-based control for linear continuous-time systems. Since conventional encryption has limited ability to de ploy in continuous-time integral computation, our work presents systematically a new design of encryption for a continuous-time observer-based control scheme. To be specific, in this paper, both control parameters and signals are encrypted by the learning with-errors (LWE) encryption to avoid data eavesdropping. Furthermore, we propose encrypted computations for the observer based controller based on its discrete-time model, and present a continuous-time virtual dynamics of the controller for further stability analysis. Accordingly, we present novel stability criteria by introducing linear matrix inequalities (LMIs)-based conditions associated with quantization gains and sampling intervals. The established stability criteria with theoretical proofs based on a discontinuous Lyapunov functional possibly provide a way to select quantization gains and sampling intervals to guarantee the stability of the closed-loop system. Numerical results on DC motor control corresponding to several quantization gains and sampling intervals demonstrate the validity of our method.This paper is concerned with the stability analysis of encrypted observer-based control for linear continuous-time systems. Since conventional encryption has limited ability to de ploy in continuous-time integral computation, our work presents systematically a new design of encryption for a continuous-time observer-based control scheme. To be specific, in this paper, both control parameters and signals are encrypted by the learning with-errors (LWE) encryption to avoid data eavesdropping. Furthermore, we propose encrypted computations for the observer based controller based on its discrete-time model, and present a continuous-time virtual dynamics of the controller for further stability analysis. Accordingly, we present novel stability criteria by introducing linear matrix inequalities (LMIs)-based conditions associated with quantization gains and sampling intervals. The established stability criteria with theoretical proofs based on a discontinuous Lyapunov functional possibly provide a way to select quantization gains and sampling intervals to guarantee the stability of the closed-loop system. Numerical results on DC motor control corresponding to several quantization gains and sampling intervals demonstrate the validity of our method
Variable post-release mortality in common shark species captured in Texas shore-based recreational fisheries
No full textThe practice of catch and release fishing is common among anglers but has been shown to cause unintended mortalities in some species. Current post-release mortality estimates used in coastal shark stock assessments are typically derived from boat-based shark fisheries, which differ from shore-based operations that expose sharks to potentially more stressful environmental and handling conditions. Recreational post-release mortality rates in shore-based fisheries must be quantified to improve stock assessment models and to create guidelines that protect species from overexploitation. Here, we partnered with experienced anglers acting as citizen scientists to deploy pop-up satellite archival transmitting tags (PSAT, n = 22) and acceleration data loggers (ADLs, n = 22). on four commonly caught sharks including the blacktip shark (Carcharhinus limbatus, n = 11), bull shark (Carcharhinus leucas, n = 14), tiger shark (Galeocerdo cuvier, n = 6), and great hammerheads (Sphyrna mokarran, n = 2). Mortality occurred within minutes to hours post-release. If evidence of mortality occurred after normal diving behavior had been re-established for 10 days, then the mortality was considered natural and not related to the catch-and-release process. Post-release mortality estimates ranged from 0% for bull and tiger sharks to 45.5% for blacktip sharks. Of the two great hammerheads, one died within 30 minutes post-release while the other exhibited mortality characteristics 14 days after release. Moribund blacktip sharks experienced on average 3.4–4.9°C warmer water compared with survivors. Recovery periods were estimated for survivors of each species and were highly variable, differing based on duration of tag deployment. High variability in responses to capture and release between species demonstrates the need for species-specific assessments of post-release mortality in shore-based recreational fisheries
Examining micropaleontology to gain insights into long -term oceanographic, glacial, and climatic processes in the Western Amundsen Sea, Antarctica
Get PDFA thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Coastal and Marine System ScienceThe West Antarctic Ice Sheet (WAIS) is undergoing rapid glacial retreat, posing a significant threat to global climate, sea level, and elemental cycles. The sector of WAIS that has exhibited the highest rates of change are the outlet glaciers draining into the Amundsen Sea Embayment (ASE). These glaciers release high volumes of glacial meltwater, disrupting the formation of dense shelf water and enabling warm Circumpolar Deep Water (CDW) to freely access the underside of ice shelves and generate basal melt. The precise timing and frequency of these events are unknown, largely due to the remote location of the ASE, heavy ice coverage, and limited satellite observations over this region. However, with concerns that a large-scale collapse of this portion of the WAIS is possible on human timescales, it is crucial we understand the specific atmosphere-ocean-ice dynamics that drive elevated melt in this region. To obtain the most complete spatiotemporal observations of this change while also avoiding the logistical challenges of working directly at the modern ice margin, we focus on the geologic record from the portions of the continental shelf that have already deglaciated. This study of ten archived sediment cores is the first-ever high-resolution diatom analysis to be conducted on the deglaciated continental shelf offshore of the eastern Getz ice shelves and the Dotson Ice Shelf, which currently see some of the most rapid volume changes of the WAIS. Diatoms are well diversified, and their composition and distribution are closely connected to ecological conditions, rendering them excellent proxies for environmental changes over time. Our analysis revealed four major paleoenvironmental units. One unit was dominated by sea-ice diatoms, one exhibited evidence of high primary production, one was characterized by a relatively high abundance of F. kerguelensis, which is commonly associated with warm CDW, and the final unit displayed elevated levels of reworked species. The distribution and relative timing of these units, as well as the overall unexpectedly low abundance of Chaetoceros and F. kerguelensis, were interpreted within the context of existing records of environmental conditions and deglacial retreat in the Amundsen Sea, shedding light on the intricate interplay between oceanic processes and glacial change over time. Most notably, diatom assemblages suggest strong similarities in water mass structure during both the present and the time of initial deglaciation following the Last Glacial Maximum; namely, these two intervals show that water column mixing, sea ice formation, and brine export are reduced due to the interference of fresh meltwater. This study also revealed discrepancies between different coring methods, highlighting the need for improved core handling in the field.Coastal and Marine System Science ProgramCollege of Scienc
Sulfate enrichment in estuaries of the northwestern Gulf of Mexico: The potential effect of sulfide oxidation on carbonate chemistry under a changing climate
No full textWater quality parameters from 2000 to 2020 were used to identify the spatial and temporal sulfate variations in estuaries of the northwestern Gulf of Mexico. Sulfate enrichment relative to conservative mixing was found to be associated with a low river discharge period from 2012 to 2014 in all estuaries. Based on reaction stoichiometry, sedimentary sulfide oxidation holds significant potential for reducing the alkalinity in estuarine waters. However, during this extreme drought, alkalinity enrichment was also occasionally observed in some of the southern estuaries along with sulfate enrichment, and when alkalinity depletion occurred, the magnitude of depletion was usually much less than what would be expected based on sulfide oxidation alone. This discrepancy can be partially explained by carbonate dissolution and other proton removal pathways (e.g., Fe-oxide dissolution), and by the uncertainties in the model used to estimate alkalinity enrichment/depletion. Under a changing climate, the close coupling between river discharge variation and estuarine sulfate dynamics will significantly impact estuarine carbonate chemistry
A look into the diversity of culturable bacterial root endophytes in Batis maritima
No full textDr. Candice Lumibao, Yue Liu, Alex Aromin, Georgia Harris, Bre Clark, Mikaelia Robinson, and Bree GarciaCoastal ecosystems face increased anthropogenic and climatic-related stressors. Batis maritima dominates coastal marshes. Known for its high salinity tolerance
Assessing the ducting phenomenon and its impact on GNSS radio occultation refractivity retrievals over the Northeast Pacific Ocean using radiosondes and global reanalysis
No full textIn this study, high-resolution radiosondes from the MAGIC field campaign and ERA5 global reanalysis data are used to assess the elevated ducting layer characteristics along the transect over the northeastern Pacific Ocean from Los Angeles, California to Honolulu, Hawaii. The height of the planetary boundary layer (PBLH) increases as the strength of the refractivity gradient and resultant ducting decrease from east to west across the analysis transect. The thickness of the ducting layer remains remarkably consistent (∼110 m) in the radiosonde data. On the other hand, the ERA5 generally resolves the ducting features well but underestimates the ducting height and strength especially over the trade cumulus region near Hawaii. A simple two-step end-to-end simulation is used to evaluate the impact of the elevated ducting layer on RO refractivity retrievals. A systematic negative refractivity bias (N-bias) below the ducting layer is observed throughout the transect, peaking approximately 70 meters below the PBL height (−5.42 %), and gradually decreasing towards the surface (−0.5 %). Further, the underestimation of the N-bias in the ERA5 data increases in magnitude westward and while the correlation of the N-bias with the minimum gradient and sharpness are all strong; there is no evidence of zonal dependence.The authors acknowledge funding support of earlier work from NASA grant (NNX15AQ17G). 491 Authors T. Winning and K. Nelson were also partially supported by research assistantship from 492 Coastal Marine System Science Program at Texas A&M University – Corpus Christi. The high 493 resolution ERA5 reanalysis data were acquired from ECMWF. The MAGIC radiosonde data 494 were provided by the Atmospheric Radiation Measurement program (ARM) Climate Research 495 Facility sponsored by the U.S. Department of Energy (DOE). 496 Author T. Winning’s current affiliation: Ventura County Air Pollution Control District, Ventura, 497 CA, 93003, USA. Author T. Winning acknowledges this work was done as an academic pursuit 498 in association with Texas A&M University – Corpus Christi and not in the author’s capacity as 499 an employee of the Ventura County Air Pollution Control District. 500 Author K. Nelson’s current affiliation: Jet Propulsion Laboratory, California Institute of 501 Technology, Pasadena, 91109, USA. Author K. Nelson acknowledges this work was done as a 502 private venture and not in the author’s capacity as an employee of the Jet Propulsion Laboratory, 503 California Institute of Technology
Jimmy Dorsey and Rafael Galvan Sr.
No full textJimmy Dorsey and Rafael Galvan Sr. smiling and talking on a couc
Luis Oliveira and Mamie Galvan
No full textLuis Oliveira and his Wife Mamie Galvan smiling together for a pictur