Theses & Dissertations
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This collection is exclusively made up of theses, dissertations, and project reports submitted as a requirement for completing a graduate degree at UPR-Mayagüez.
If you are a UPRM graduate student and you are looking for information related to the deposit process, please refer to https://libguides.uprm.edu/repositorioUPRM/tesis
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PublicationAnálisis descriptivo de las instituciones ancla potenciales en la región oeste de Puerto Rico y su aportación a la resiliencia agroalimentaria en momentos de crisis( 2024-04-30)This non-experimental, descriptive quantitative study, based on surveys, focused on analyzing Potential Anchor Institutions (PAIs) and their role in strengthening food security during times of crisis in the western region of Puerto Rico through their influence on the production, distribution, and marketing of local products. It was found that most of these institutions classified themselves as anchor institutions. They acknowledge their organizations have actively contributed to fostering production and the transfer of knowledge within the local agri-food sector. These entities endorse sustainable agricultural practices, actively enhancing community food security and resilience by aiding the distribution of local agri-food products and supplying food to vulnerable populations through their community kitchens. The primary challenges in their roles as anchor institutions stem from reliance on external funds and susceptibility to natural disasters.
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PublicationTesting proficiency outcomes in first-year basic English at UPRM( 2024-04-26)This study focuses on the levels of English Language Proficiency (ELP) current cohorts of incoming college students possess and acquire after a semester of instruction in undergraduate English courses at the University of Puerto Rico in Mayaguez. The goal of the study is to identify the proficiency gaps that may exist between the sampled population and whether ELP within the three target language skills; vocabulary, reading comprehension, and grammar, improved after coursing a semester in Basic English II at UPRM. Data collection sampled a population of 142 students of varying linguistic backgrounds and utilized a diagnostic exam administered at the beginning and end of the academic semester to determine changes in student proficiency. The results were analyzed using descriptive and inferential statistics employing a paired samples t-test. The tests were broken down into overall and individual skill analyses to better analyze proficiency changes within the target skills. Descriptive analysis showed a 10% improvement in overall grade scores, even though 27% of the sample population continued to fail the diagnostic after completing the course. Additionally, inferential statistics concluded a small significant difference between pre-and post-test data based on the sampled paired t-test results. These results suggest that the majority of students enrolled in the Basic English track curriculum are proficient in the English language. However, there are potential concerns for the effectiveness of the current curriculum and assessments due to many participants failing the diagnostic after having received a semester of instruction.
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PublicationSulfated glycosaminoglycans culture surface for cell manufacture and cell-based applications( 2024-04-26)Heparan sulfate (HS) and heparin (HEP) are glycosaminoglycans known for their pivotal roles in regulating and enhancing growth factor availability, influencing various cellular functions including adhesion, proliferation, differentiation, and gene expression. While their individual use in cell culture is recognized for supporting the preservation of both exogenously added and endogenously secreted growth factors, their singular application has limitations. In this study, we propose a novel approach by combining HS and HEP with collagen (COL) to promote cell adhesion through integrin activity. We investigated the effectiveness of rHS/COL at different sulfation levels, demonstrating its capacity to release and regulate Sonic Hedgehog (SHH) ligand concentration by 5.3-fold and enhance ligand signaling strength within 120 hours of cell culture compared to a commercial surface. Additionally, rHS09/COL emerged as a promising alternative substrate for cell culture, ensuring cell growth in serum-free media conditions for 3 to 10 days, surpassing the growth rate of cells cultured on a commercial surface in 2% FBS media. These findings, attributed to the release of rHS/COL ligands and the prevention of growth factor degradation, address the challenges associated with manufacturing mesenchymal stem cells (MSCs), including rapid ligand degradation and the need for constant ligand replenishment to ensure cell growth. Our proposed cell substrate culture offers a cost-effective alternative, overcoming limitations associated with the availability of xeno-free media in the market.
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PublicationEffect of the combination of three water regiments and biomass production of five cover crop species on the health of six soil orders( 2024-04-16)The inadequate management of agricultural lands and climate change have increased problems like desertification, salination, and soil erosion, which greatly concern scientists, farmers, and agronomists. Conservation of the fertile soil layer represents a challenge under current climate change conditions and standard management practices. Implementing conservation practices such as using cover crops has shown the potential to help control grasses, and when harvested, improve soil fertility, and help control insects and diseases of economic importance. Utilizing the soil health indicators from the Natural Resources Conservation Service (NRCS), a series of studies were conducted to observe how five cover crop species and three irrigation regimens impacted six soil series from six distinct soil orders. Ten parameters were selected based on their agronomic importance, which included β-Glucosidase, Active Carbon, pH, pH in CaCl2. Conductivity, Organic Matter, Hot Water Extractable Carbon, Plant Quantity, Plant Height, and Plant Biomass. When comparing the cover crops, the Jack Bean (Canavalia ensiformis) provided the most favorable results on the soil-based for the three water regimes, especially on parameters such as β-GLU, AC, EC, OM, and HWEC, well as proved to be the species with the most resistance to changes in water regimen and soil moisture. However, the results tend also to indicate that the water regimens had the most impact of all the treatments, with the Normal Humidity (NH) regimen consistently showing the most positive impact irrespective of cover crop species on the soil-based parameters similarly resulting in mostly positive changes in β-GLU, AC, EC, OM, HWEC and the plant parameters such as biomass production and plant height.
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PublicationShort-term effect of three tillage and two soil conservative practices in the soil health and eggplant production in a Mollisol( 2024-04-09)Intensive agricultural production can lead to soil health depletion, which can be reduced using conservation practices such as minimum tillage and the incorporation of organic matter. Contrary to conventional tillage practices, conservation tillage leaves at least 30% of crop residue on the soil surface, which helps to minimize soil properties disruption. This study aimed to assess the soil health effect of incorporating biochar saturated with effective microorganisms on the Mollisols-Jacaguas treated with three cover cycles using the combination of four cover crops with three soil tillage treatments, Conventional Plow (CP), Spader and Keyline. The results of this study indicated that incorporating the plant residues of four CC cycles with Keyline tillage had a significant effect on the soil health within the short-term. The interactions of biochar incorporation with CC and tillage treatments had no significant effect on soil pH, LOC, PLFA and Saturated hydraulic conductivity because the small amount of biochar applied (<0.3%) was not sufficient to affect the above-mentioned soil properties at the short-term.