Texas A&M University-Kingsville: AKM Digital Repository
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The effect of cooperative learning on English language oral communication among ESL community college students
No full textEnglish as a Second Language (ESL) students are reluctant to use oral communication skills, such as listening and speaking, in academic settings. ESL students in college classrooms in English-speaking countries often report feelings of inadequacy and frustration while participating in oral classroom activities (Kim, 2000; Leki, 2001; Morita, 2004). This quasi-experimental study examined the effect of cooperative learning (CL) structures on the English language oral communication skills of listening and speaking among ESL college students. The research questions explored the difference in ESL students’ pretest/posttest listening and speaking scores who participated in CL strategies in an advanced oral communication class versus students who did not participate in cooperative learning strategies. A total of 33 ESL college students enrolled in two advance oral communication courses in a pre-English program at a Southeast Texas community college served as participants for this quasi-experimental study. The study was framed from Vygotsky’s Social Constructivism Theory (Vygotsky, 1978). Conceptually, this study was based on the premise of CL (Johnson, Johnson & Holubec, 2013), which is defined as group work activities that bring students together to work collaboratively in the process of learning language. Demographic data was collected via a background questionnaire, while pre- and posttest data was collected utilizing the Woodcock Muñoz Language Survey-III (WMLS III), and the Student Oral Language Observation Matrix (SOLOM). Pre-existing data from an AccuPlacer ESL Placement Test at the target college was also utilized. Independent sample t-test was used to analyze the pre and posttest data. The findings indicated that ESL students who participated in CL strategies (N=14) displayed significantly different listening and speaking posttest scores on the WMLS III as compared to ESL students who did not (N=19). Additionally, the SOLOM observations indicated that the participants did not demonstrate a significant difference in listening and speaking pre-and post-observations. The findings of this study support the notion that cooperative learning has the potential to positively enhance the listening and speaking skill development of ESL college students. Specifically utilizing Four Corners, Group Investigations, Gallery Walks, Numbered Heads Together, Fishbowl Debates, Group Presentations, and Think, Pair, Share activities. This study provides a basis for the understanding of the use and effects of cooperative learning, to enhance oral language communication competency in higher education.
Key terms: cooperative learning, ESL college students, bilingual educatio
Modeling and performance comparsion of topologies of DC-DC boost converter in photovoltaic systems
No full textThe DC-DC boost converters are employed in various applications of modern world. One of the most important applications is in Photovoltaic (PV) systems. The energy collected from the solar source needs to go through a DC-DC converter first. The DC-DC converter boosts up the low DC voltage coming from the PV panels to a high DC bus voltage and it drives the DC-AC inverter. Thus, the efficiency and the control of the DC-DC boost converter plays a very important role in this entire process. The conventional DC-DC converter circuit has been used as a reference for a long time in different applications. Different control techniques have been applied on them to get the best performances possible. Recently, some new topologies have been proposed to improve the efficiency of this converter, but very little research has been done to analyze them. In order to inspect these topologies, proper mathematical modeling is required, and state space average model is one of the efficient techniques to do that. The objectives of this thesis are to obtain state-space average models of the new topologies and apply PID controller on them to compare the performance of the new topologies with the conventional one. To get the expected result, the simulations will be done using MATLAB Simulink models
Exploring social justice education in South Texas preservice bilingual teacher preparation programs
No full textOver the last few decades, the United States of America (USA) has experienced an increase in the number of K-12 students due to increasing waves of immigrants and the high birth rate of immigrant families. Most of today’s K-12 classes reflect a diversity of non-English speaking (NES) students whose English proficiency challenges their academic performance and hinders their access to academic instruction. From its enactment in 1968 to the No Child Left Behind Act of 2001, the Bilingual Education Act (BEA) has served as a legal frame to help school districts facilitate equal access to education for those students. Besides the BEA, numerous studies have reported the necessity of promoting and embracing diversity as well as practicing social justice in education. However, few studies have reported on ways preservice bilingual teacher programs are preparing teacher candidates for social justice. This research study explored the ways social justice is included in four South Texas bilingual teacher education programs. These programs are in areas extending from Austin, Texas to the border with Mexico (the area lying from Austin to Rio Grande (RGV)). This study focused on bilingual teacher educators’ perspectives, as well as the perspectives of preservice teachers enrolled in those programs. The researcher used a simultaneous qualitative mixed method design based principally on a complete narrative strategy with supplementary data collection strategies. Data were collected from interviews in four bilingual teacher preparation programs and from descriptive syllabi of the degree plan course core. The sampling included seven (7) teacher educators and thirteen (13) junior and senior bilingual teacher candidates. Supplementary data came from documental analysis of course syllabi. Data analysis was performed using Ginsburg’s narrative approach. Alongside this approach, there was a special focus on source triangulation technique aimed at finding consistency between the course syllabi description, teacher educators and teacher candidates’ stories and experiences on social justice. Findings showed coherence and incoherence between participants’ beliefs and practice of social justice education. Findings suggested divergences and similarities in the four research sites in terms of preparing bilingual teacher candidates for social justice education. Finally, the researcher drew implications, and made recommendations for bilingual teacher education programs and further research orientation
Quantifying the benefits of street trees in Corpus Christi, Texas, using i-Tree Streets™
No full textStreet trees in urban environments have the potential to be positive components of community identity and a source of economic benefit. A stratified random sample for 3% of street segments in Corpus Christi, Texas, was conducted and the benefits of street trees were evaluated via I-Tree Streets™, providing the City’s first urban street tree inventory and new insight into Streets™ sample design. One, 2% and 3% combined sample inventories were cross evaluated for structure and species metrics as well as i-Tree Streets™ benefit analysis including 32 random and 32 stratified 1% iterations. Tree counts per segment were highly correlated between the two samples (97% similarity). Annual benefits of street trees from the combined 3% sample revealed a 1.8 million returned annually from Corpus Christi’s right of way street trees. Results build on previous research indicating stratification drastically increases sample accuracy, even when stratifying by a large area, such as a city management zone. In Corpus Christi, stratification resolved 96% of sample species count variance between 1% and 2% samples; 1% sample iterations stratified by management zone generated a 4% increased benefit output compared to 3% sample benefits via i-Tree Streets™. In communities not able to perform a 3% sample, a 1% sample could provide similar benefit outputs. More research is required to determine the replicability of these results in other urban communities and environments.
Keywords: urban tree resource; tree inventory; i-tree™; cost-benefit; street trees; stratified sampl
Thermal hydraulic analysis of NBSR thermal shield
No full textThis research develops a detailed thermal hydraulic model that enables the investigation of the thermal characteristics of the National Bureau of Standard Reactor (NBSR) thermal shield. The thermal shield is a steel-lead light water cooled structure that protects the biological shield from excessive radiation heating. While in full power operation, the thermal shield cooling system of the NBSR reactor removes approximately 210 kW thermal heat load from the radiation shielding surrounding the reactor vessel. There are 187 copper tubes (0.5” outer diameter) cooling down the thermal shield with water. The thermal shield geometry is constructed in SolidWorks and then imported to ANSYS Fluent to analyze heat load distribution. This analysis uses the constant heat flux to represent the heat source from the reactor to perform computational fluid dynamics (CFD) calculation on the shield with different conditions. The simulation would investigate the minimum flow and the maximum number of consecutive no-flow tubes for safe operation. The analysis result would be used to propose coolants that exhibit better thermal behavior required for cooling
Optimization of the expression of tetracycline monooxygenase (Tetx)
No full textTetracycline is an important group of antibiotics used for agricultural and clinical purposes to treat infectious diseases caused by pathogenic bacteria [1]. It functions by selectively binding to the 30S subunit of the prokaryotic ribosome to effectively halt protein synthesis [2]. Its efficiency in clinical settings is being threatened by an increasing number of antibiotic resistant strains of bacteria. Resistance has been shown to occur through active efflux, ribosomal protection and from the enzymatic degradation catalyzed by flavin dependent enzymes [3]. One of these enzymes is tetracycline monooxygenase (TetX), which has been shown to degrade the antibiotic by monohydroxilation and enzymatic breakdown. The aim of this research is to develop strategies to combat antibiotic resistance in pathogenic bacteria through rationale design of inhibitors of TetX. Study of the kinetic mechanism that will initiate this aim has been limited due to less amount of TetX enzyme produced [6 mg/L of culture] as reported by Wright et al [2]. My research leads off to produce large quantities of active TetX needed for the proposed study. We successfully transformed the plasmid encoding TetX gene plasmid pET22a+ onto competent Escherichia coli cells Rosetta (DE3) pLysS and DH5α. With a developed expression trial protocol (at different induction temperature and incubation period), and novel activity assay (ratio μM oxygen consumed/s to total amount of protein in sample), we were able to determine which cell strain best expresses the enzyme. We discovered that DH5ά with an induction period of 20hrs at 300C had the highest specific TetX activity under all conditions used (725 ±10 U/mg). This was a breakthrough as subsequent experiments on this research will be based on this condition for its detailed catalytic mechanism. We further developed a procedure to obtain large amounts of active enzymes. It was observed that addition of Flavin Adenine Diphosphate (FAD) cofactor to lysis buffer, upon lysing the cell, increased the specific activity, ~9 fold higher (3900 ± 250) with less error as compared to the previous activity recorded. This increase was proposed to be due to FAD binding with the protein thereby making it more stable and thus preventing the enzyme from denaturing while been extracted from the cell. This was yet another breakthrough as this will allow for the accurate determination of the kinetic mechanism of the enzyme which will result in the propagation of errors from multiple kinetic assays by varying the concentration of oxygen and tetracycline. Screen of DH5ά colonies to further determine which colony produces the most amount of TetX, the chosen colony had a specific activity of 9800 ± 250 (~15 fold higher) with 5% error and a yielded stock of ~20 mg/L of TetX more than twice the amount previously reported [2]. This will aid this research group in developing a purification protocol for the detailed kinetic study of the enzyme
What non-cognitive factors influence Hispanic students' GPA/SAT?
No full textIt is an unfortunate fact that Hispanic students score significantly lower on the Scholastic Aptitude Test than European American students. Past research has indicated factors that negatively predict academic achievement include self handicapping and test anxiety. This study uses correlations to investigate the relative influences of these constructs in prediction of both SAT scores, and overall GPA in Hispanic and European American students. Undergraduate students participated in an hour and a half long survey session to be compensated with course credit
Comparability of growth and development of Capsicum annum (pepper) due to biomass and inorganic nutrients
No full textTwo hundred plants of Capsicum annum were arranged in four randomized complete block design under greenhouse conditions to study the impact of an organic extract, Medicago sativa (alfalfa) and commercial fertilizer, Miracle-Gro® (MG) on the growth and development of C.annum. The NPK content of alfalfa and MG were 3:1:2 and 30:10:10 respectively. Treatments were represented as T1, T2, T3, T4 and C. These treatments were according to nitrogen concentration of the working solution where 10ml of OE equals 1ml of MG (T1), 20ml of OE equals 2ml of MG (T2), 30ml of OE equals 3ml of MG (T3), and 40ml of OE equals 4ml of MG (T4) whereas the control (C) received only water. Plants were treated every 15 days and data collected seven days after treatment, and every 14 days thereafter. Plant growth parameters measured include height; number of leaves, buds and flowers; fresh and dry weights of vegetative and root parts; and total chlorophyll content. Statistical analyses of the data generally indicate no statistically significant difference in plant growth and development due to the treatments. However, 40 ml of OE seemed to outperform all the concentrations of MG in all growth parameter
Study of sustainable energy development in Nigeria
No full textIt is no doubt that there is big demand for energy in Nigeria. Among the Organization of Petroleum Exporting Countries (OPEC) members, Nigeria stands in the 6th position in available oil reserve and daily production. Apart from known huge oil reserves, the Nigeria's natural gas reserve has been estimated to be above 166 trillion standard cubic feet (TSCF). Newer novel technologies like shale gas exploration affect the oil and gas prices. The future of oil will be continually influenced by new reserves being made possible by newer technological innovation. Meanwhile, renewable energy will increasingly play a bigger role in the future global energy mix. Therefore, there is a need for Nigeria to critically look at its Sustainable Energy Development (SED) plans. This study investigated the efforts being made in Nigeria to encourage SED, and explained the reasons of not yielding the anticipated results from those efforts through analyzing data from existing literatures and surveys conducted by the author. This study also thoroughly investigated whether over dependence on oil & gas for energy and power is actually a major factor militating against the needed interest in SED or not. The results from this research eventually identified the challenges of SED in Nigeria.
Keywords: Sustainable Energy Development, Renewable Energy, Survey
Optimal utilization of large-scale battery storage systems for microgrid applications
No full textThe integration of energy storage system (ESS) provides various benefits to microgrids such as mitigating renewable generation variability and reducing operation cost. One challenge in designing a microgrid system is determining the optimal size of ESS. Sizing of ESS has become more complex due to the independent power and energy ratings inherent in battery storage systems (BSS). Sizing a BSS for both required power output and energy storage capacity requires an in-depth analysis to produce both optimal scheduling capabilities and minimum investment costs. This thesis proposed a framework to determine the optimal ratings of BSS based on an optimal scheduling analysis and cost-benefit analysis for a set of given constraints both in the islanded and grid connected microgrid expansion applications. Mixed integer linear programing (MILP) algorithm was developed to solve the optimal sizing and scheduling problem to minimize the total cost and increase microgrid reliability. The viability and effectiveness of the proposed framework was validated by numerical simulations