Digital Commons @ Texas A&M University-San Antonio
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Growth Models and Their Stability Analysis for Populations of a Single Species
Get PDFUnderstanding the patterns of population growth for human beings or other animals is important for effective society and resource management. We study several population growth models for a single species to exhibit how the secret of growth patterns can be unlocked from a mathematical perspective. The models are derived from differential equations involving rate of population change, birth/death rate, population carrying capacity, and delayed population influence on population growth. Solutions of the population as functions of time are obtained and plotted to show their visual effect. Equilibriums of the solutions are also analyzed to understand the long-term behavior of population growth. Stability analysis is provided to see the long-term impact of interruption from the equilibrium solutions. The models are employed to explain various interesting natural phenomena involving population growth
Water Resources Science and Technology Fall Seminar Series: Marcus Gary (Edwards Aquifer Authority)
No full textDr. Marcus Gary with the Edwards Aquifer Authority introduces the hydrology of the Edwards Aquifer in South Central Texas and what it means to the water resource management for the San Antonio area
Texas Navy Association Collection, 1823-1861
Get PDFThe Texas Navy Association Collection consists of historic newspapers regarding Tejas, the Republic of Texas, and the Texas Navy.
The Texas Navy Association is a nonprofit 501(c)3 organization committed to preserving the history of the three Navies of Texas. Formerly known as the Texas Navy, Inc., the Texas Navy Association was formed by an act of the 63rd Texas Legislature, sponsored by Aaron Robert “Babe” Schwartz, on August 27, 1973.https://digitalcommons.tamusa.edu/findingaids/1174/thumbnail.jp
Dual Isotopic (O & N) Approach in the Assessment of NO3- Pollution in an Urban River
Get PDFDeterioration of urban waterways has become a major environmental concern as management and recreational goals are often hampered by poor water quality. The San Antonio River (TX, USA), whose upper reaches, including its headwaters, pass through a highly urbanized community, is vulnerable to pollution from a myriad of anthropogenic activities within its initial 17-km stretch. This investigation applied a dual-isotope approach to characterize water samples collected during the wet season (May–June, 2019) in order to assess the potential sources of nitrate in the urban stretch of river. The δ15N-NO3 and δ18O-NO3 values ranged from + 5.56 to + 10.89‰ and + 3.26 to + 5.90‰, respectively. The ranges of these values suggest that urban sewage and effluent coupled with denitrification were the major sources of nitrate being introduced into the San Antonio River. Biological assimilation and denitrification resulted in the consumption of residual NO3− downstream and caused a positive shift in the isotopic compositions of NO3−. Furthermore, shifts in δ15N-NO3 by about + 2.0‰ between a zoo and downtown San Antonio indicated that sewage and urban wastes were major sources of nitrate in the San Antonio River
Capital Market Penalties and Corporate Violations of the Three Pillars (Operations, Reporting, and Compliance) after COSO 2013 Internal Controls: Integrated Framework
Get PDFCurrent literature is somewhat unclear on how corporate violations under the new set of governance environments versed in the Internal Controls Integrated Framework issued by COSO (acronym of Committee of Sponsoring Organizations of the Treadway Commission) influence shareholders’ activism. Initially published in 1992, these guidelines faced a significant revision with proactive improvements in 2013. Since the first emission, this guidance has focused on providing safe-keeping basic standards for organizations to follow regarding the integrity of corporate governance and enterprise risk management by designing and implementing stable internal controls. The handbooks’ primary approach builds upon an environment of permanent improvement of self-regulatory governance in three main catalysts or pillars: (i) operational safety; (ii) financial statements reporting assurance; and (iii) regulatory compliance
Aflatoxin in Dairy Cattle Water Troughs
Get PDFOne of the most commonly found mycotoxins, aflatoxin, has been an emerging concern for the milk and dairy industry and a continued concern for the human food supply and cattle feed industry. There is a possibility of this carcinogenic mycotoxin being found in water and several studies have found them in water storage tanks, treated wastewater systems, and even in bottled water. With the potential presence in water, this study explores the possibility of aflatoxin in water troughs found on dairy farms which could be one of the exposures to cattle linked to causing aflatoxin in milk. Trough water samples were collected from two Southeast Texas dairies and tested using PCR and electrophoresis to determine if there was a presence of Aspergillus flavus DNA, which is one of the aflatoxin-producing species of mycotoxins. At this time, no aflatoxin was found in the trough water samples, but more research and possibly more forward and reverse primers are needed for Aspergillus flavus. Aflatoxin has many different forms and can be produced by several different species that are found in the Aspergillus sect. flavus. Further research is needed before concluding if aflatoxin could be found in water troughs
Ferrate-Pretreated Directional Solvent Extraction for Hydraulic Fracturing Produced Water: Technical and Economic Feasibility Studies
Get PDFProduced water (PW) generated from hydraulic fracturing operations contains varying amounts of crude oil, sand and dissolved ions, and is typically characterized as hyper-brine. It is often untreatable by existing desalination technologies. This study presents using the directional solvent extraction (DSE) technique to desalinate multiphasic, synthetic produced waters (SPW) using diisopropylamine (DIPA) as the extraction solvent and a ferrate pretreatment method. DSE with ferrate pretreatment achieved an average solvent efficiency of 0.25, 0.13 and 0.03 mL water/g solvent at 1 M, 2 M and 4 M salinity, respectively. The water extraction, turbidity reduction and salinity reduction efficiency were better for DSE with ferrate-pretreatment than compared to DSE alone. DSE\u27s salt rejection rates in the product water were consistently over 95 %, while turbidity reduction was dependent on ferrate dosage used for pretreatment. This process costs an estimated $1.23 per m3 of water extracted from a 4 M brine for a single-pass operation with 95 % heat recoveries
Interventions for Improving Social-Communication Skills for Adolescents and Adults with ASD: a Meta-analysis
No full textThere is a lack of services to support adolescents and adults with ASD in different areas including social-communication intervention. The purpose of this study is to conduct a meta-analysis determining effects of social-communication interventions in improving social-communication skills for adolescents and adults with ASD. A search of databases yielded 2,353 potential documents of which 41 documents met inclusion criteria. The finding of this study indicated that social-communication interventions across all documents are moderately effective in improving social-communication skills for adolescents and adults with ASD. This study investigated the effectiveness of social-communication interventions for these populations and also examined differential effects based on the moderator categories. There are statistically significant differences found for some potential moderators (interventions, implementers, communicative functions, and type of setting). Additional details on implementation, limitations, and future research are discussed
Historias de Una Pandemia: Documenting Latina/o/x Stories During Covid-19 Through Performed Storytelling
Get PDFUsing oral histories and narratives collected during the Covid-19 pandemic, a student-led performance invites consideration about the role of language, cultural, and social pluralities in creating a socially just world
Las Bexareñas and Their Wills: Women’s Material Culture and Cataloguing Practices in Spanish San Fernando de Béxar
No full textThe women of San Fernando de Béxar (modern-day San Antonio, Texas) on the northern edge of New Spain faced the many challenges of frontier life. The belongings of these women were limited compared to that of women in other parts of New Spain, yet the Béxar women accumulated, largely through inheritance, religious paintings, statues, and crucifixes as well as clothing, jewelry and kitchen wares. Some women had luxuries and furniture from other parts of New Spain or the world. Through their wills, women catalogued their most prized possessions. Not all women left behind wills, but those who did catalogued their precious belongings with care. This study uses wills from San Fernando de Béxar in the late eighteenth and early nineteenth centuries to examine what possessions women included in their wills and explains how they catalogued this property