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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Now showing 1 - 5 of 3015
  • Publication
    Marchitez súbita de la sandía (Citrullus lanatus): Hospederos y manejo
    ( 2024-05-08) Torres Burgos, Yaneris L. ; Estévez-de Jensen, Consuelo ; College of Agricultural Sciences ; Cabrera Asencio, Irma ; Hernández Heredia, Ermita ; Department of Agro-Environmental Sciences ; Velázquez Augusto , Wesley
    One of the challenges that farmers face to achieve an optimal (or desirable) performance in their production is the management or control of diseases caused by phytopathogenic organisms, as well as those caused by viruses. The production of watermelon [Citrullus lanatus (Thunb) Matsun & Nakai] in the southwestern area of Puerto Rico has been challenged by the management of viral diseases such as the Watermelon vine decline (WVD) caused by the Squash vein yellowing virus (SqVYV). This virus is transmitted by the whitefly (Bemisia tabaci). In this research, the presence of this virus and others such as Papaya ringspot virus (PRSV), Zucchini yellow mosaic virus (ZYMV), Cucumber mosaic virus (CMV), Watermelon mosaic virus (WMV) was evaluated in seedlings germinated in three nurseries, in three watermelon producer farms, and surrounding weeds in watermelon and other cucurbit fields. The presence of Potyvirus was detected in the seedlings in one of the nurseries even though they did not show virus symptoms. The percentage of symptoms caused by viruses on the three farms was considerably different for each one. Regarding the weeds and other cucurbits, the virus that prevailed was PRSV. Additionally, at the Fortuna Experimental Station in Juana Díaz Puerto Rico, experiments were carried out in two different times where the incidence of the disease in a sowing (DBCA) of watermelon of the “Crimson Sweet” variety was evaluated. Different treatments were used to control the whitefly (Bemisia tabaci). Only the presence or absence of vectors was considered, and in both experiments the presence of Bemisia tabaci and Aphis gossypii was observed. The presence of SqVYV and other viruses such as PRSV was detected. As for the yield, it was higher in the second experiment compared to the first. These results demonstrate that it was possible to reach the harvest stage despite the presence of different viruses on the field.
  • Publication
    Design of a low SWaP dual-band radiometer for UAS remote sensing applications
    ( 2024-05-09) Novoa García, María Celeste ; Rodríguez-Solís, Rafael A. ; College of Engineering ; Medina Sánchez, Rafael H. ; León Colón , Leyda V. ; Department of Electrical and Computer Engineering ; Amador Ramirez, Andre
    This work presents the design of a dual-band (L/Ka) receiver for a Dicke radiometer to measure Sea surface salinity. The analog front-end was designed and characterized. The system noise figure was found to be 0.5118 dB, with a gain of 49.1235 dB and bandwidth of 136 MHz around 1.41 GHz, and the system noise figure was found to be 1.7815 dB, with a gain of 74 dB and bandwidth of 8 GHz around 31.5 GHz. The digital back-end was implemented on a ZYBO Z7 7020 platform. The digital receiver reads the voltages for the L-band and K-band detectors, and the system reference, performs the switching between bands and the reference signal for the Dicke operation, performs the integration, calculates the brightness temperature, and stores the brightness temperature data, along with the date, time, and position data, on an SD card.
  • Publication
    Influencia de la motivación en la L1 y L2 de los estudiantes puertorriqueños
    ( 2024-05-07) Rodríguez Rúa, Melissa ; Morales Reyes, Alexandra ; College of Arts and Sciences - Art ; Rivera, Rosita L. ; González, Melvin ; Department of Hispanic Studies ; Hernández , Itza
    The present research examined the levels of motivation towards the mother language, Spanish, and second language, English, of 29 Puerto Rican students located in a public school in the southern area of Puerto Rico, considering variables such as international posture, ideal self in L1/L2, instrumental motivation and intrinsic motivation. These dimensions were measured through two questionnaires. In addition, questions were analyzed, at the demographic level, to measure socioeconomic level and observe whether it has any impact on the dimensions studied. The results reveal that, in general, students show high levels of motivation. However, when evaluating the effects of the student’s socioeconomic level on the variables, significant differences were found in instrumental motivation. These findings highlight the importance of continuing to strengthen language skills in Puerto Rican students, as well as promoting a positive attitude toward the languages that converge on the island to achieve better educational and personal development.
  • Publication
    Creación y validación de estructuras de datos para aproximar EDP con diferencias finitas en mallas adaptativas
    ( 2024-05-10) Ordóñez Rodríguez, Claudia Patricia ; Castillo, Paul E. ; College of Arts and Sciences - Sciences ; Rúa Alvarez, Catalina M. ; Narciso Farias , Flor ; Department of Mathematics ; Hernández Hernández, Carlos I.
    Diferentes aplicaciones relacionadas con la física pueden ser modeladas matemáticamente por Ecuaciones Diferenciales Parciales (EDP) como la ecuación de Poisson. Este tipo de ecuaciones con condiciones frontera de Dirichlet y Newmann en el caso bidimensional son aproximadas con métodos numéricos como el método de Diferencias Finitas (DF), especialmente en Mallas con Refinamiento Adaptativo (AMR, abreviatura en inglés de Adaptive Mesh Refinement) en regiones específicas por sus posibles restricciones en su solución. En esta investigación se lleva a cabo un estudio teórico y computacional de la discretización del problema de Poisson en 2D de forma matricial utilizando el método de DF, tanto en mallas uniformes como en AMR. Se emplean estructuras de datos como Tabla de dispersión (HT, abreviatura en inglés de Hash Table) para representar las células de la malla, lo que implica un análisis detallado de las características de estas estructuras, así como las de sus operaciones y su complejidad computacional. Además, se muestra una variación de métodos de interpolación que permiten la comunicación de las células de los diferentes niveles. Entre los resultados obtenidos, se verifica la convergencia y se realiza un estudio de diferentes propiedades de la matriz como número de condicionamiento, patrón de esparcidad, que se refiere al gráfico de puntos de elementos no nulos de las matrices dispersas, y relación de la interpolación aplicada. Adicionalmente, se lleva a cabo una generación de AMR con varios criterios de refinamiento, mostrando un análisis de eficiencia y de colisiones para las HT.
  • Publication
    Improving surface-enhanced Raman scattering by the implementation of pillararenes on silver nanoparticles
    ( 2024-05-09) Vázquez Pérez, Germán ; Bezares, Francisco J. ; College of Arts and Sciences - Sciences ; Marrero-Soto, Pablo J. ; Sánchez Quintero, Dilsom ; Department of Physics ; Cabrera Ríos, Mauricio
    Surface-enhanced Raman Scattering (SERS) spectroscopy is a highly sensitive and specific detection method. This technique is useful for sensing extremely small concentrations of analytes, that could be harmful for human health and food security. Therefore, it is of foremost importance to study methods that can enhance the sensing capabilities of SERS. This work presents an experimental and statistical analysis of optimal parameters for the synthesis of metallic nanoparticles, which are responsible for the enhancement of the Raman signal. After the parameter optimization, a layer of dimethoxy pillar[5]arene was deposited onto the Ag nanoparticles to study the selectivity of the technique. These are highly symmetric macrocycles that have the capacity to attract certain types of molecules into their central cavity. The layer of pillar[5]arenes was optimized for concentration and thickness, which allowed studying their capabilities to capture toxic analytes and detect them using SERS.