Texas A&M University-Kingsville: AKM Digital Repository
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Familismo and culture identity's influence on stress levels of college students
No full textAre stress levels influenced by family and/or cultural identity? According to ACHA, 44.9% of college students experience stress considered more than average. Previous research indicates that family expectations are not part of the stress within college students. However, there have been limited studies regarding stressors that South Texas college students experience. The current study focuses on the influence that family and culture identity contribute to the amount of stress that South Texas college students experience. A total of 120 participants were recruited from Texas A&M University- Kingsville. Of these participants, 80 were females and 40 were males. The participants in this study had an average of 21.94 years old, with a range of 18 to 25 years old. Participants were requested to complete an online survey that measured acculturation levels based on the Short Acculturation Scale for Hispanics (Marin et al., 1987), stress levels based on the Perceived Stress Scale (Cohen et al., 1983), and familismo’s influence on beliefs and values through the New Familism Scale (Steidel, et al., 2003). It was hypothesized that low familismo scores predict high perceived stress, students who have one or more parent who is an immigrant exhibit higher perceived stress, and higher scores of cultural conformities lead to lower perceived stress. Findings indicated a positive relationship between support towards family and stress levels – and a marginal positive relationship between subjugation of self to family and stress. According to the Family Stress Theory, family commitment and subjugation of self to family are considered as stressors, while coping resources are social support, familial interconnectedness, and external stressors are acculturation, social pressure, and other mental health issues
Morphological growth and development predictors of transpiration in Capsicum annum
No full textPlants, unlike other living organisms, survive and thrive in place throughout their lives. They live and survive on passive absorption of nutrients and transpire water in the process. The water so transpired evaporates into the atmosphere in the soil-water-root-plant-atmosphere evapotranspiration continuum. It indeed means that effective evapotranspiration is an indication of an effective nutrient absorption since nutrient absorption is a passive process. One important question that has not been sufficiently addressed is what plant morphological growth parameter or a combination of growth and development parameters predicts plant transpiration, and what is the level of accuracy for such a prediction?
In this proposed thesis research, leaf area, stomatal conductance, relative height growth, rate of transpiration, fresh leaf biomass, dry leaf biomass, fresh root biomass, dry leaf biomass, and leaf temperature will be studied as growth and development parameters using a Capsicum species. The data will be statistically analyzed using SAS 9.01 to decipher which growth and development parameter or a combination of such parameters predict the rate of transpiration.
Also, the degree of predictability of such parameters as well as the suitable regression equation of the prediction will be generated
Using deep learning to identify oil spill slicks by analyzing remote sensing images
No full textOil spills are one of the most serious hazards to marine and coastal environments. In order to act quickly, oil slicks must be monitored effectively and discovered as soon as possible to minimize pollution and avert further damage to the environment. Oil spills may now be quickly identified due to advancements in remote sensing technology and artificial intelligence algorithms. The accuracy of machine learning models is limited by the fact that they can only
feed-forward picture categorization without assistance from a comprehensive trainable framework. Deep learning models, on the other hand, improve detection accuracy based on its high feature extraction and autonomous learning capabilities. However, since there is not a unique optimal detection approach for clearly identifying and differentiating oil spills, it is vital to advance the technology and create improved models for more precise identification and improved segmentation, taking advantage of new techniques in geospatial feature extraction. The objective of this thesis is to develop a deep learning model using U-Net architecture with an ensemble of pre-trained deep neural network as backbones for instance segmentation of oil spill remote sensing images (Synthetic-aperture radar Images) to improve the detection accuracy, Intersection Over Union metric, and performance of existing methods. U-Net architecture with an ensemble of pre-trained networks has a good performance with an accuracy of 96% and an Intersection Over Union accuracy score of 70%. This is due to stacking four pre-trained models as our encoder with a combination of focal and dice loss, and then allowing U-Net to figure out the decoder path of the architecture. The results showed that the ensemble U-Net architecture performed better than other existing algorithms and that the loss function, size of the validation and training data are significant factors in pixel level classification of oil spill images
The role of Chinese immigrant parents' capital in the development of their children's Chinese heritage language
No full textThis mixed methods study used Bourdieu’s social, cultural, economic, and symbolic capital as the theoretical framework to examine and explain Chinese immigrant parents’ four forms of capital in the development of their children’s Chinese heritage language (CHL) development in Texas. This study deployed a mixed methods sequential explanatory research design that included a survey adapted from a published study with permission. This study used convenience sampling and snowball sampling to recruit participants in the quantitative phase. A total of 123 surveys were completed by Chinese immigrant parents who had school age children in Texas. Hierarchical multiple linear regression was used to analyze how well Chinese immigrant parents’ capital could predict their children’s CHL development after controlling for children and parents’ demographic variables. Findings showed that Chinese immigrant parents’ four forms of capital significantly predicted CHL development of their children. Among the four forms of capital, cultural and symbolic capital were significant predictors for children’s CHL development while economic and social capital were not significant predictors.
This study included a follow-up qualitative phase that used purposeful sampling to obtain participants from the survey sample (n = 123). The researcher interviewed seven participants from those who completed the survey in phase one. This study in the qualitative phase investigated Chinese parents’ expected returns from their capital invested in their children’s CHL development. Findings revealed that Chinese immigrant parents expected tangible economic, cultural, social, and symbolic returns from their investment in their children’s CHL development. Chinese immigrant parents expect future job opportunities for their children not only in China but also in the United States. Chinese immigrant parents expected their children to understand the history and culture of China, and to gain academic advantage from their Chinese development. Chinese immigrant parents believed that Chinese development would enable their children to communicate with families and socialize with people in China. Chinese heritage language development could bring their children symbolic capital, such as rewards and recognition from people around them. Findings in the qualitative study showed that in an English-dominant society such as the United States, the most important Chinese language environment for children was created by Chinese immigrant parents at home. Chinese immigrant parents were the primary provider of Chinese language environment to their children in the United States
Development of a technique for reliable recovery of testable Asian Citrus Psyllid from field deployed sticky cards
No full textDiaphorina citri (D. citri) is the vector of Candidatus Liberibacter asiaticus (CLas), the bacterium associated with Huanglongbing (HLB), a devastating citrus disease. The sticky trap is widely used for D. citri monitoring and risk assessment of CLas. However, recovery of D. citri individuals from sticky traps for DNA or CLas assessment is not practiced. The goal of this research is to develop a technique for reliable recovery of D. citri from field deployed Asian citrus psyllid (ACP) sticky traps for successful use of D. citri DNA for CLas detection. Four treatments were evaluated, T1=ACP sticky trap with mesh and the use of Histo-clear®, T2=ACP sticky trap with mesh and no Histo-clear®, T3=ACP sticky trap with no mesh and use of Histo-clear®, and T4=ACP sticky trap with no mesh and no Histo-clear®, at six time points (0, 3, 7, 10, 14 and 21 days) after trap deployment in a citrus grove in South Texas. Three parameters were tested: D. citri DNA quality, quantity using a spectrophotometer and detection of the mitochondrial cytochrome c oxidase subunit 1 gene by PCR, targeting ~800-bp fragment. The best DNA recovery technique (T1= ACP sticky trap with mesh and the use of Histo-clear®) was then used to test D. citri for the presence of CLas by qPCR. Following a 14-day acquisition access period, most D. citri acquired CLas with Ct values 37. Exposure of ACP sticky traps with mesh at different weathering periods did not significantly affect the proportion of CLas-positive D. citri (G = 7.29, df = 5 P = 0.20). This study may assist in D. citri DNA and CLas detection recovered from ACP sticky traps, in addition to monitoring of its populations
Evaluation of weed management systems in Imidazolinone tolerant grain Sorghum (Sorghum bicolor) in South Texas
No full textWeeds remain one of the most limiting factors in grain sorghum (Sorghum bicolor [L.] Moench) production due to the lack of herbicides available for weed control. Recent developments of imidazolinone-tolerant sorghum hybrids provide an opportunity for uses of herbicides previously unavailable for this crop. The objectives of this study were to evaluate weed control, herbicide impact on crop injury, and grain and herbage mass (HM) yields using imazamox alone, and in diverse herbicide programs. The sorghum hybrid ‘ADVXG009IMI’ was planted flat on plots measuring 3.9 meters wide by 9.1 meters in length with 96-cm row spacing and a rate of 148,200 seeds per ha-1. Field trials were conducted in 2019 and 2020 across three locations in South Texas; Kingsville, Corpus Christi, and Beeville. Twelve herbicide treatments were compared to a non-treated control (NTC) for preemergence (PRE) and postemergence (POST) weed control and crop damage, while the hybrid was evaluated on grain yield and HM production. Herbicide treatments included imazamox alone at 53g and 79g ai/ha EPOST and MPOST or tank mixed with other herbicides; atrazine (ATZ), prosulfuron, dimethenamid-P, and pyrasulfotole + bromoxynil EPOST. ATZ PRE followed by (fb) ATZ + prosulfuron POST was significantly less effective suppressing Texas millet (Urochloa texana Buckley [R.] Webster) than ATZ PRE fb ATZ + imazamox POST. Replacing prosulfuron with imazamox and with the addition of ammonium sulfate (AMS) POST, weed density was significantly reduced at both 14 and 28 days after treatment (DAT). Additionally, late season annual grass control was greatest with ATZ + dimethenamid-P PRE followed by atrazine + imazamox POST. This treatment resulted in significantly higher weed control and some of the highest grain yields across all three locations. The lowest yielding and least controlled were the non-treated control (NTC) and atrazine PRE followed by atrazine + prosulfuron POST
Spatial distribution of the snake genus Chironius in Bolivia
No full textThe genus Chironius is a diurnal group of medium to large, terrestrial-arboreal, colubrid snakes distributed throughout Central and South America. The genus' broad Neotropical distribution and lack of current knowledge inspired this study. Currently, 10 species of Chironius
occur within the geographic boundaries of Bolivia. An updated species distribution map (SDM) of four Bolivian Chironius species, specifically C. exoletus, C. flavolineatus, C. fuscus, and C. scurrulus, was made using data from the 2014-2019 Powell/Eversole Bolivian field expeditions
and the information in published scientific papers and online databases (i.e., VertNet, ARCTOS, GBIF, speciesLink). ArcGIS software was used to develop the current range maps. Also, data layers (i.e., climate, vegetation, landcover) currently available for Bolivia were used to examine the relationships between ecological variables and distribution patterns. Using spatial analysis
options in ArcGIS and overlaying the data points, patterns of clustering and habitat preference were identified in Chironius and analyzed for the four species listed above. In general, Chironius showed a preference to inhabit lowland tropical rainforests, humid montane forests, and savannas or open formations. This agrees with much of the literature. Specifics on climate, land cover, and
vegetation for the species is also analyzed, and possible explanations are briefly explored. The increase in the populations of the major cities in different Departments of Bolivia is having a large effect on the habitats of Chironius and is more of a threat to wildlife than global warming
currently. The limits and biases in the data due to poor sampling and incomplete records is noted
Investigation of 'Candidatus Liberibacter asiaticus' prophages in Texas and Florida
No full textHuanglongbing (HLB) is one of the most severe bacterial diseases affecting world citrus production. At present, three distinct prophage types, Type 1, 2 and 3, have been found in the genome of ‘Candidatus Liberibacter asiaticus’ (CLas), a causal agent of HLB. It has been proposed that the presence of these prophages in CLas genome may contribute to bacterial virulence, and the prophage sequence information has been utilized to differentiate CLas strains. In this study, CLas-positive DNA samples prepared from citrus leaf and root and Asian citrus psyllids that were collected during summer and winter seasons in Texas and Florida were examined for the presence of prophage type(s) by PCR. Results showed that more than 90% of samples examined in the study has both prophage Type 1 and 2 while prophage Type 3 was not detected in the current study. Statistical analysis indicated a strong co-occurrence of these two prophages regardless of geological location, season and tissue type, while the occurrence of the prophage types detected in the DNA extracts was independent of state, season and tissue type. Nucleotide sequencing of prophage Type 1 and 2 amplicons followed by phylogenetic analysis showed that Type 1 amplicons derived from citrus DNA samples and Type 2 amplicons from both citrus and ACP DNA samples share high sequence homology with those present in Florida CLas strains. Of interest, the amplicon sequencing revealed the presence of minor nucleotide sequence variation in ACP-derived Type 1 sequence which shared higher sequence homology with China and California CLas (gxpsy and SGCA5) strains, which resulted in the formation of a separate ACP Type 1 clade in the phylogenetic tree
Parametric study of sandwich composite armor
No full textOver time, man have struggled to cope with the modern-day types of ballistic threats. Consequently, it became important to understand the principles behind the design of the armor systems. The objectives of this study are to analyze and improve on the performance of sandwich-structured armor systems upon ballistic impact load. The model of the armor was in the form of sandwich structure with fiber reinforced polymers FRP as the skin and Aluminum Alloy Al3003 as the core. The core was filled with Silicon Carbide (SiC) and Aluminum Oxide (AL2O3). Finite element analysis, using ABAQUS CAE was performed on the designed armors upon an impactor at a velocity starting at 1200m/s until the velocity penetrates the armor. The effect of face sheet material, thickness and core material on the energy absorption capacity of the armors were observed. The difference in energy absorption values was observed to be minimal for the two face sheet materials used in this research. Increase in shear modulus of ceramic material was observed to increase energy absorption capacity. Validations of the simulation results were carried-out for Kevlar-29/Epoxy laminate using experimental result from a literature. Upon completion of all the analysis, it was found that these specific designed armors are strong enough to protect against relatively high ballistics threats, up to 1500m/s impact velocity
Identification of fungal plant pathogens in irrigation water in the Lower Rio Grande Valley of Texas
No full textThe Lower Rio Grande Valley of Texas (LRGV) is an area with high agricultural activity which uses the Rio Grande River as a primary irrigation water source. The Rio Grande River receives water from many streams that could transport pathogens, thus contaminated irrigation
water with plant pathogens can be the source of inoculum for many agricultural crops in the LRGV. However, there is no data or research on the fungal plant pathogens present in the Rio Grande River. This study evaluated the water feeding the canal from the Mercedes irrigation
district reservoir and the water arriving at a citrus orchard for the presence of fungal plant pathogens by Illumina sequencing. Results show that fungal communities from both sampling locations were different. A total of 994 fungal Operational Taxonomic Units (OTUs) were
obtained from the six samples analyzed and 284 OTUs were detected in all samples. At the Phylum level, there was a higher relative abundance of Chytridiomycota followed by Basidiomycota and Ascomycota. However, phylogenetic analysis showed higher abundance of
Ascomycetes genera identified, compared to other fungal groups. Ten OTUs were identified as fungal plant pathogens, nine were identified in the water collected at the citrus orchard, and four of those were also found at the irrigation district. The citrus orchard contained five different additional plant pathogens that were only found at this citrus orchard along with the four that were also found at the irrigation district. The irrigation district contained four plant pathogens coinciding with those of the citrus orchard, and had one additional plant pathogen found only in this location. This study indicates that fungal plant pathogens are present in irrigation water and
could potentially be a source of inoculum to plant diseases. This study provides new insight to the potential risks and distribution associated with plant pathogens in irrigation water in the LRGV