Facultad de Ciencias Exactas y Naturales

URI permanente para esta comunidadhttp://10.0.96.45:4000/handle/11056/14053

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Analysis of the influence of GLONASS signals in the processing of one regional geodestic Network
(Universidad Nacional, Costa Rica, 2018-01-31) Paniagua Jimenez, Diana; Valverde, Jose
In recent years, there has been an increase in the number of satellites available for positioning using space techniques, highlighting the GPS and GLONASS systems. The comparative analysis of the results obtained from the calculation of a network of GNSS stations in Europe, from data processing using the Bernese 5.2 software, which, among other things, stand out for presenting an improvement in the joint treatment of GPS and GLONASS data with respect to the previous version of the program. The primary purpose that motivated the research is the need to determine whether or not the results of the combination of data from both systems are better than those obtained with version 5.0, since research has shown that the GNSS processing result in the Bernese 5.0 program tends to be less accurate than the result of processing with only GPS data. Consequently, it was found that the inclusion of GLONASS observables in the processing does not impact significantly on the results.
Aporte ambiental de la planta de tratamiento de aguas residuales Los Tajos en la remoción de contaminantes fisicoquímicos y microbiológicos
(Universidad Nacional, Costa Rica, 2022-01-31) Mora Aparicio, Carmen; Alfaro-Chinchilla, Carolina; Perez-Molina, Junior Pastor; Vega-Guzmán, Ilena
The objective of the study was to analyze the environmental contribution, in terms of removal of physicochemical and microbiological pollutants, from the Los Tajos Wastewater Treatment Plant (WWTP) to the Torres River. Physicochemical and microbiological data was analyzed including WWTP inflows and outflows (OBD, OCD, TSS, STT, N-NH4 +, P-PO4 3-, Oils, MBAS, and fecal coliforms). The difference in the concentration of pollutants in the Torres River before and after the construction of the WWTP was analyzed using R 3.6.1, associated with seasonality. According to the Dutch Index Methodology, the Torres River was severely polluted before the construction of the WWTP, and the degree of contamination increases following the WWTP discharge, mainly during the rainy season. The WWTP shows significant removal of seven of the eight parameters analyzed, with the most representative removal percentages being: TSS (68.5%), OBD (49.8%), and Oils (54.7%). The quantitative contribution of the WWTP to the Torres River was demonstrated by removing thousands of Mg of pollutants from wastewater during the years of operation (2015-2020), mainly OCD (26,791.8 Mg), STT (24,162.6 Mg), OBD (12,290.0 Mg), and TSS (30,267.7 Mg). Finally, building the WWTP’s next stages, including secondary treatment, is needed to improve the removal of organic matter, surfactants, and nutrients.
Concordancia entre los cursos de introducción a la matemática universitaria y el programa de estudios preuniversitarios
(Universidad Nacional, Costa Rica, 2018-07-25) Castillo Sánchez, Mario; Gamboa Araya, Ronny Wilson; Hidalgo Mora, Randall
This article reports data about academic achievement in introductory university level mathematics courses taught by the Department of Mathematics at the Universidad Nacional de Costa Rica and the concord-ance between the contents of these courses and those of pre-university (secondary education) programs. Information was collected by analyzing grades from introductory university mathematics courses for all programs of study in the period 2011-2016, the courses offered, and the program of studies in mathemat-ics in secondary education. This was done to determine academic performance and to make comparisons between introductory mathematics courses at university level and the program of mathematics studies in secondary education, to stimulate revision and updating of the courses and generate recommenda-tions. The results show that there are high failure and dropout rates in most introductory university-level mathematics courses, and that there are differences between the content that students study in secondary education and the content of introductory mathematics courses offered by the Universidad Nacional; prior knowledge is therefore relevant for academic achievement in introductory university mathematics courses. In addition, the data collected on content and aspects of methodology and evaluation show important differences in the way mathematical contents are addressed at each level. This implies that analysis of the contents of these courses should be carried out and strategies should be created, to guarantee a minimum level of prior knowledge in students when beginning the study of these subjects at university level.
Control de calidad de imagen y dosimetría, para mamografía digital, utilizando el fantoma Normi Mam Digital
(Universidad Nacional, Costa Rica, 2018-07-26) Calderón-Mata, Angélica; Arce Corrales, Luis Pablo; Mejías, Ricardo
In Costa Rica there is not an explicit recommendation given by the Regulatory Authorities for the utilization of a specific Phantom; that is why experts have to explore what is offered in the market. One of the most remarkable equipment is Normi Mam Digital made by PTW. This article introduces the results of image and dosimetry quality control, applied to the Normi Mam Digital Phantom to validate how the equipment complies with the recommendations of Human Health Series no. 17. The obtained results were satisfactory and achieved the regulatory tolerances by international sanitary organizations.
Diseño de una metodología para evaluar el manejo sostenible de los bosques naturales de la Zona Norte, Costa Rica
(Universidad Nacional (Costa Rica), 2021) Salas Garita, Cynthia; Soliño Millán, Mario; Ortiz Malavassi, Edgar
A partir de un conjunto de indicadores de referencia, se diseñó una herramienta para la evaluación “ex post” de la sostenibilidad de unidades de bosques naturales manejados en Costa Rica. Este conjunto se desarrolló utilizando una estructura jerárquica de principios, criterios e indicadores de sostenibilidad. La lista de referencia resultante consta de 5 principios, 12 criterios y 30 indicadores, clasificados como esenciales por un grupo de expertos en manejo forestal en Costa Rica. El conjunto de indicadores permite estudiar las dimensiones y atributos que delimitan la sostenibilidad de los ecosistemas. El procedimiento de selección y la probable contribución de este conjunto al manejo forestal aborda, en primer lugar, las condiciones económicas, sociales, ecosistémicas e institucionales de Costa Rica. Sin embargo, el conjunto de indicadores es útil para otras regiones del mundo, previa adaptación de los umbrales a las condiciones locales del ecosistema. Adicionalmente, la dimensión ecosistémica (productividad, estabilidad, adaptabilidad) se ratifica como condición de primer orden para la sostenibilidad, pero los expertos refuerzan la idea de que la dimensión institucional (equidad y gobernanza) es un desafío para la evaluación de la sostenibilidad.
Estudio preliminar con respecto a los efectos en la salud de trabajadores y su relación con la exposición a emisiones gaseosas volcánicas. Un caso de estudio en dos volcanes activos de Costa Rica
(Universidad Nacional, Costa Rica, 2022-01-31) Ortiz Apuy, Erick; Mora Barrantes, Jose Carlos; Sibaja - Brenes, José Pablo
The objective of this research was to carry out a preliminary diagnosis of the relationship between volcanic gaseous emissions and health effects present among workers of the National System of Conservation Areas (SINAC) of the Poás and Turrialba volcanoes of Costa Rica. [Methodology] Ambient air quality was measured by the presence of gaseous emissions (SO2 (g), H2S (g), HCl(g), HNO3 ( ac) and HF(g), with sampling carried out in 7 strategic points during 7 months. Analyses were performed using different analytical techniques (ion chromatography, spectrophotometry, portable meters). At the same time, interviews were conducted with a sample consisting of 16 park rangers from the study sites, and their medical records were analyzed to detect a preliminary relationship between exposure to gaseous emissions and reported pathologies. [Results] The principal results (pollutants above the detection limit) reported for the two national parks indicated that the highest value in this study was that of SO2 (average of 3 h) in the Poás Volcano (1.90 ± 0.11) mg/m3 . The highest concentration of SO2 in Turrialba was (0.40 ± 0.04) mg/m3 during the same period. During the evaluation of park rangers’ health, it was found that the most frequently reported pathologies that impact health in the study population were irritation of the mucous membraneseyes (n = 9), headaches (n = 8), and fatigue (n = 8). [Conclusion] The results obtained for the gaseous emissions and their possible relationship with pathologies and medical records indicated by park rangers provide a baseline for future research on the subject. A greater number of measurements over longer periods of time is recommended. At the same time, it is necessary to use surveys and carry out medical controls that include tests on specimens such as blood, urine, hair, and saliva, as well as the use of biological and chemical indicators that allow a pathology to be more directly related to a specific chemical contaminant.
Gender, self-efficacy and performance in a mathematics test
(Universidad Nacional, Costa Rica, 2022-01-31) Zamora Araya, José Andrey; Montero-Rojas, Eiliana; Smith-Castro, Vanessa; Moreira-Mora, Tania Elena; Zamora-Calvo , Pablo; Quintero, Karla; Matarrita Muñoz, Stefani Daniela
El propósito del estudio fue examinar la relación entre autoeficacia matemática y el rendimiento en la prueba nacional de bachillerato en matemáticas, que considera otros predictores psicosociales relevantes y los efectos moderadores del sexo y del centro educativo. [Metodología] El diseño del estudio fue de corte observacional y transversal, con la participación de 487 estudiantes de undécimo año, provenientes de colegios públicos de la Gran Área Metropolitana de Costa Rica. Se aplicaron varios instrumentos para medir: sexismo hostil y benevolente, percepciones de igualdad de género en las habilidades matemáticas, autoeficacia matemática y habilidades de razonamiento.[Resultados] Los resultados del análisis multinivel bayesiano de efectos aleatorios confirmaron las diferencias a favor de los hombres en la medida de autoeficacia, donde el sexo del estudiantado fue un moderador entre la relación de la autoeficacia matemática y el puntaje de la prueba. Además, se encontró que, según el sexo, la asociación entre autoeficacia y rendimiento también se encontró moderada por el centro educativo. [Conclusiones] Entre las conclusiones se destaca que, si el efecto moderador del colegio entre autoeficacia y rendimiento difiere por sexo, esto implica que las acciones dirigidas a promover la autoeficacia no tendrán el mismo resultado en los hombres y en las mujeres, lo que evidencia la necesidad de desarrollar intervenciones diferenciadas.
Gestión del riesgo de desastres: Competencias para una nueva cultura hidroambiental
(Universidad Nacional, Costa Rica, 2022-01-31) Charpentier, Claudia; Moreira-Segura, Cristian; Arauz Muñoz, Jeannette; Barrantes, Gustavo
The study was aimed to develop and validate competencies, methodologies, and teaching resources for a new hydro-environmental culture in disaster risk management for Costa Rican students and teachers of the second cycle of the Cahuita Excelencia Elementary School in Limón. The research was developed under an interpretive and propositional qualitative approach with the participation of nine national and international experts (3 in Disaster Risk Management [Group 1], 3 in Climate Change [Group 2], and 3 in Education [Group 3]), using the Delphi method which consisted of 3 phases: preparation, consultation, and consensus. Results indicate that Groups 1 and 2 developed 43 competencies, of which ten were validated by each group. Group 1 distributed competencies into conceptual, internal, and external, while Group 2 only distributed cognitive competencies, both for children and teachers, taking into account indicators, didactic resources, and methodologies. During Phase 3, Group 3 adjusted and validated the competencies developed by Groups 1 and 2, which consist of 20 competencies and a series of resources and methodologies. It is concluded that competencies will contribute to guarantee better preparation for vulnerability and risk events caused by climate change. The reference educational material could be adjusted to other regions of Costa Rica and Latin America.
Teacher Reflection on a Teaching-Learning Situation Regarding the Concept of Relation in Secondary Education
(Universidad Nacional, Costa Rica, 2022-01-31) PICADO, MIGUEL; Loría Fernández, José Romilio; Espinoza González, Jonathan
This study is part of the research in didactics of mathematicson teacher training. In particular, the study focuses on the knowledge of mathematics teachers, taking as a reference the theoretical approaches of the Mathematics Teacher’s Specialized Knowledge (MTSK) model and teacher reflection as a professional competence. The study corresponds to a descriptive-qualitative research, based on an instrumental study of cases, whose purpose is to describe and analyze the manifestations of mathematics teachers of Secondary Education when they observe a teaching-learning situation that shows a teacher of mathematics teaching the concept of relation. For this, narratives written by seven Secondary Education mathematics teachers in service were used, which indicate some aspects identified by them as relevant from the observed situation. The analysis of the gathered information was carried out by defining categories, subcategories, and analysis units based on the components of the MTSK model. The results indicate that participating teachers accentuate, in their manifestations, attributes mainly associated with didactic knowledge of mathematical content. The reflection of this group of teachers is characterized by three specific aspects of the MTSK model: teaching, learning, and knowledge of the topics. It is interpreted that teacher reflection has been influenced by the professional experience of the teachers participating in the study.

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