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


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Now showing 1 - 5 of 3050
  • Publication
    Regularidad global para un problema quasi-lineal sobre regiones irregulares
    ( 2024-05-14) Gonzalez Pugliese, Rafael Eduardo ; Rios Soto, Karen ; College of Arts and Sciences - Sciences ; Velez Santiago, Alejandro ; Portnoy, Arturo ; Romero Oliveras, Juan ; Department of Mathematics ; Villavicencio Mattos, John
    En este trabajo investigamos la existencia, unicidad, estimaciones a priori y continuidad global para un problema eliptico generalizado con condiciones de frontera tipo Neumann o Robin. Ademas, los coeficientes de orden inferior en general no estan acotados. En condiciones minimas, mostramos que el problema admite una solucion debil Holder continua globalmente
  • Publication
    Detection and characterization of gram-positive and gram-negative bacteria in stormwater from Quebrada del Oro at Mayagüez
    ( 2024-05-10) Berrocales Vázquez, Katiushka Paola ; Cafaro, Matías J. ; College of Arts and Sciences - Sciences ; Díaz Lameiro, Alondra M. ; De Jesús, Marco A. ; Department of Biology ; Rodríguez Ramos, Ingrid
    Rainwater is considered an alternative water source to mitigate the increase in water de- mand; however, due to the impact of climate change, plastic pollution and substances such as per and polyfluoroalkyl affect its quality. Likewise, runoffs reach the surface water providing greater biodiversity that can change its composition. However, this water transports a diversity of micro- organisms that can in turn adhere to different substrates like sediment particules, stones, and structures made by humans. Some microorganisms, such as members of the Enterobacteriaceae family, are commonly used as indicators of fecal contamination in surface waters. In this study, we evalu- ated the detection and quantification of Coliforms, Enterococci, Staphylococci and Actinobacteria from stormwater in Quebrada del Oro stream in Mayagüez. Water was collected in sterile bags at four sampling points across the slope near the UPRM Chemistry Building before reaching the stream and directly from the stream. Samples were plated in Tryptic Soy Agar (TSA) media and incubated at 37°C for 24-48 hours. Plate counting was performed to determine CFU/ml of water. We identified isolates from both runoff rainwater and Quebrada de Oro stream. Then, DNA extraction was performed using a microbiome DNA purification kit for q-PCR analysis. Isolates from both water samples presented Gram-negative and Gram-positive bacteria. Rapid Colilert kit anal- ysis detected the presence of E. coli in runoff water. In the Quebrada del Oro stream we also de- tected coliform bacteria. Coliforms in both samples of rainy days(stream and runoff) were higher than the other groups. Enterococci was the predominant group in the samples of drys days. Enter- obacteriaceae and Enterococci members are distinguished for being indicators of fecal contamina- tion in bodies of water such as rivers, streams and beaches.
  • Publication
    Quality assessment of images from projection devices using deep neural networks
    ( 2024-05-08) Tamayo Zapata, Kelly J. ; Manian, Vidya ; College of Engineering ; Ducoudray, Gladys ; Torres, Raul E. ; Department of Electrical and Computer Engineering ; Font Santiago, Cristopher B.
    Image quality perception in projectors is critical for enhancing user experience in education, business, and entertainment. This research proposes an automated visual assessment tool for accurate image quality assessment (IQA) in DLP projector images. The research utilizes two types of neural networks: No-Reference IQA (NR-IQA) for evaluating blur, blob, and pixel defects, and Full-Reference IQA (FR-IQA) for evaluating color distortion. The methodology involves neural network models, transitioning from a pre-trained VGG16 to a more complex ResNet, and ultimately a refined ResNet + PyramidNet for NR-IQA for the NR-IQA; and a Simasese pre trained VGG16, and Siamese ResNet models for FR-IQA. For the refined NR-IQA ResNet + PyramidNet model AUC of 94%, 96%, 98, 94% in high-quality, blur, blob, and pixel defects, respectively were achieved, with good test outcomes, particularly in projectors with visual defects. Conversely, the FR-IQA Siamese ResNet model achieved AUC rates of 94% and 96% for high quality and color-altered images, respectively. It also demonstrated good performance with real defective scenarios. Limitations were encountered in both situations, where intentionally unfocused images or the presence of shadows caused misclassification of blur or blobs, or when handling new images captured under varying conditions. Despite the limitations, incorporating a diverse dataset, including both simulated and real defective projector images, significantly enhanced model performance and defect identification accuracy.
  • Publication
    Evaluación de puntos críticos mutacionales de Lactato dehidrogenasa en ganado Senepol y Holstein que difieren en los genotipos del receptor de prolactina asociados con el pelo corto
    ( 2024-04-12) López Nieves, Lourdes Esther ; Pagán Morales, Melvin ; College of Agricultural Sciences ; Sánchez Rodríguez, Héctor L. ; Casas Guernica, Américo A. ; Department of Animal Science ; Carmona Negrón , José A.
    In this study we evaluated levels of lactate in blood and tissue of Senepol (SEN) and Holstein (HO) cows genotyped for the shorthair gene (homozygous, heterozygous and wild-type). We determined single nucleotide polymorphisms (SNPs) in LDHs (lactate dehydrogenase) candidate genes (LDHA, LDHB, LDHC, LDHD) and estimated MBV (Molecular Breeding Values) and GPTA (Genomic Predicted Transmitting Ability) for different traits. In addition, we observed the medulla characteristics of the hair of these animals. Lower lactate values were obtained in blood (P=0.0164) and tissue (P=0.0365) for homozygous versus heterozygous SEN, which could be due to the truncation of the PRLR that causes an inactivation of gene expression causing a reduction in hair size. We were able to show associations between SNP in LDHs with certain productive, reproductive, and type characteristics. There was no effect of genotype for short hair on the diameter of the medulla and index of the medulla of the rump area (P=0.7259 and P= 0.0871, respectively), however, there was an effect on ribs (P<0.0001) and shoulders (P<0.0001). These results suggest that shorthaired cattle provide greater thermoregulatory capacity by combining several traits associated with hair.
  • Publication
    Spatial and temporal patterns of diffuse attenuation coefficient in Guánica, Puerto Rico: 15 years after development of a watershed management plan
    ( 2024-05-07) Guzmán Morales, Alba L. ; Armstrong, Roy A. ; College of Arts and Sciences - Sciences ; Hernández, William J. ; Cruz Motta, Juan J. ; Department of Marine Sciences ; Acuña Guzmán, Salvador F.
    Decreased water quality in coastal environments due to land alterations by human activities has caused stressed and degraded coral reefs worldwide. The consequences of decreased water quality are not limited to coral reefs but also affect the quality of people’s lives by increasing the incidence of diseases, so areas highly impacted have been prioritized for management. The Guánica Bay Watershed Management Plan was developed to reduce the non-point sources of pollution that arrive at the bay and to protect adjacent coral reefs, however, 15 years have passed since its creation and management actions have not been evaluated. The purpose of this study was to evaluate the effectiveness of the management actions implemented in the Guánica Bay watershed. Therefore, the objective of this study was to describe temporal trends (2002-2008 and 2016-2022) of remotely sensed diffuse attenuation coefficient at 490 nm (Kd490), a water quality indicator, in one managed (Guánica Bay) and three non-managed (Guayanilla Bay, Descalabrado River, and Guanajibo River) estuaries in south and southwest Puerto Rico. This was achieved by integrating ocean-color satellite imagery from MERIS-Envisat and OLCI-Sentinel-3 sensors that were sampled using a beyond-Before-After-Control-Impact approach. An additional oceanic site was selected to evaluate continuity between sensors estimates. The imagery was processed using SNAP to extract Kd490 values in the estuaries. The analysis for the beyond-BACI found significant differences between periods (before and after) but the changes were unique to each location within estuary. The lowest Kd490 values and variability within estuary was observed in Guánica (range 0.05–0.1 m-1) and the highest Kd490 values were observed in Guayanilla (0.35 m-1). The southern estuaries showed similar temporal trends, all having a peak in 2018 and a trough in 2020. Kd490 did not decrease in Guánica after the implementation of management actions, which can be related to the passage of several hurricanes during the after period. Further analysis should be done as new data is available and after the implementation of the last management actions suggested in the plan.