https://www.revistas.una.ac.cr/index.php/uniciencia/issue/feed Uniciencia 2019-08-27T09:46:40-06:00 Yuri Morales López revistauniciencia@una.cr Open Journal Systems <p>The mission of <strong>Uniciencia</strong>&nbsp;journal is to share, without profit, research results and offer high quality inputs to the national and international scientific community in such a way that they allow the scientific and cultural development of our society. It is a&nbsp;semiannual&nbsp;journal that began in 1984. The journal is indexed in: SciELO, Redalyc, LATINDEX Catalog, DOAJ, Emerging Source Citation Index (ESCI), among others.<br><strong>Publishing Entity</strong>: Faculty of Exact and Natural Sciences. Universidad Nacional, Costa Rica.<br><strong>Thematic areas</strong>: biology, physics, computer science, mathematics, chemistry, topography and geodesy (and their teaching).<br><strong>E-ISSN</strong>: 2215-3470<br><strong>Contact</strong>: Yuri Morales-López, Editor • <strong>Email</strong>: revistauniciencia@una.ac.cr</p> https://www.revistas.una.ac.cr/index.php/uniciencia/article/view/11476 Effect of two cytokinins and a growth inhibitor on the in vitro tuberization of two genotypes of Solanum tuberosum L. cvs. Atlantic and Alpha 2019-08-27T09:46:40-06:00 José Antonio García-García dendrogar@yahoo.com José Bernal Azofeifa-Bolaños jb12azo@gmail.com Frank Solano-Campos frank.solano.campos@una.cr Rafael Orozco-Rodríguez rafael.orozco.rodriguez@una.cr <p>This investigation was carried out to evaluate the effect of two cytokinins: 6-benzilaminopurine (BAP) (6.5 mg l<sup>-1</sup>) and kinetin (K) (2.5 mg l<sup>-1</sup>), as well as the growth inhibitor abscisic acid (ABA) (1.0 mg l<sup>-1</sup>) on the <em>in vitro</em> tuberization capacity of two potato varieties: Atlantic and Alpha. The basal culture medium MS (1962) was used as a control. The responses were different between varieties. In cv. Atlantic, the analysis of the number (NM), weight (WM) and diameter (DM) of microtubers indicated that the addition of growth regulators did not affect induction and development of microtubers. However, when BAP was used, a non-significant increment of 41 % was observed in the number of the microtubers compared to the control treatment, from 2.6 to 4.4. The addition of cytokinins and ABA to the medium did not have a significant impact on the development of microtubers. In cv. Alpha the cytokinins used without ABA increased the number of microtubers, which were larger and heavier than those of the control treatment. In this variety, ABA significantly reduced the values of the NM, WM and DM variables. The exogenous action of cytokinins in the culture medium is likely to have caused an endogenous hormonal imbalance in the Atlantic and Alpha genotypes which interfered with their innate microtuberization ability, a result that was even more evident for cv. Alpha, which showed the need to continue optimizing protocols of genotype-specific systems in potato tissue culture to increase yield and seed quality.</p> 2019-07-31T00:00:00-06:00 ##submission.copyrightStatement## https://www.revistas.una.ac.cr/index.php/uniciencia/article/view/11477 Validation of a liquid chromatography detection method (HPLC-DAD) for the determination of aloin in Aloe vera food products 2019-08-27T09:46:40-06:00 Ricardo Ulate-Molina reulate@itcr.ac.cr Henry Borbón-Alpízar henry.borbon.alpizar@una.ac.cr José Pablo Sibaja-Brenes jose.sibaja.brenes@una.ac.cr Ilena Vega-Guzmán ivega@aya.go.cr Maricruz Arguedas-González maricruz.arguedas.gonzalez@una.ac.cr <p>Aloin is an anthraquinone found in a wide variety of food products made from aloe, which can cause laxative effects and prolonged ingestion increases the risk of gastrointestinal cancer. In this study, parameters for aloin analysis and extraction methodology were validated using High Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD). Aloin concentration was determined in 14 commercial products consumed in Costa Rica. The quality values evaluated were linearity (<em>R</em> = from 0.9995 to 0.999995), reproducibility (recovery percentage = from 96.7% to 99.9%), intra-day precision (coefficient of variation = from 0.24% to 1.47%), inter-day precision (coefficient of variation = from 1.65% to 2.68%), limit of detection (from 0.063 mg/L to 0.228 mg/L), limit of quantification (from 0.126 mg/L to 0.452 mg/L) and selectivity (≤ 0.063 mg/L). The majority of the evaluated food products showed a concentration below the maximum value allowed (10 mg/L), with values between 0.2 ± 0.1 mg/L and 4.8 ± 0.1 mg/L of aloin, with an average standard deviation of 0.41 mg/L. Liquid samples presented higher values than the rest of the matrices. Two of the samples (RU/BT1/39A and RU/BT1/45B) were reported with concentrations higher than the maximum aloin value allowed (14.2 ± 0.1 mg/L and 19.0 ± 0.1 mg/L). The consumption of these products could have a long-term harmful effect on health, since they exceed the limit mentioned above.</p> 2019-07-31T00:00:00-06:00 ##submission.copyrightStatement## https://www.revistas.una.ac.cr/index.php/uniciencia/article/view/11479 Evidence on some pedagogical and didactic trends present in the Costa Rican mathematics curriculum 2019-08-27T09:46:40-06:00 Marianela Zumbado-Castro mazumbado@uned.ac.cr <p>The pedagogical and didactic trends present in the Costa Rica math curriculum have led the style of the lesson organization proposed by the Ministry of Public Education since 2012. Every step in the class is based on ideas from different sources: constructivism, socioculturalism, realistic pragmatism, realistic mathematical education, as well as Japanese, French and American ideas. This paper aims to present the link between theory and the actions that can be performed with students by posing a problem, solving it, and having the teacher’s assistance, as proposed in the Costa Rican curriculum. It can be established that each trend is present and produces an impact when performing each step proposed for classwork since the foundation and the historical and theoretical backgrounds are solid; therefore, the methodological proposal can be trusted.</p> 2019-07-31T00:00:00-06:00 ##submission.copyrightStatement## https://www.revistas.una.ac.cr/index.php/uniciencia/article/view/11480 Stochastics and special education teaching: centered and uniform distributions 2019-08-27T09:46:40-06:00 José Marcos López-Mojica mojicajm@gmail.com <p>This article is part of a more extensive project aimed at analyzing stochastics teaching and learning processes in special education. The teaching of this educational level is presented here using a qualitative approach. From a theoretical perspective, three guiding axes were considered: the epistemological, cognitive and social axes. The larger study was divided into three phases.&nbsp; This paper will be focused partly on the second phase, particularly on the introduction of the probability distribution for four teachers in a guided study scenario, using teaching scripts and logbooks as instruments.&nbsp; Data was recorded in video and in writing. In addition, operational body and teaching analysis unit were applied. Results include the teachers’ gradual acquisition of the ideas of sample space, probability measure, random variable (relative frequencies), distribution, and symmetry.</p> 2019-07-31T00:00:00-06:00 ##submission.copyrightStatement## https://www.revistas.una.ac.cr/index.php/uniciencia/article/view/11481 Mathematical proof: meaning, types, attributed functions, and relevance as part of math teachers’ professional knowledge 2019-08-27T09:46:40-06:00 Cristian Alfaro-Carvajal crisalfaro@correo.ugr.es Pablo Flores-Martínez pflores@ugr.es Gabriela Valverde-Soto gabriela.valverde@ucr.ac.cr <p>The objective of this paper is to conduct a theoretical study on the meaning of mathematical proof, taking into consideration three main elements: concept, types, and functions. This is a qualitative and descriptive research. The method used to collect and analyze information is the conceptual analysis. Four sources of information were considered: dictionaries, textbooks, previous research, and the mathematics curriculum of the Ministry of Public Education of Costa Rica. The technique for collecting the information was the bibliographic review. It was determined that proof has different meanings depending on the context; that the types of mathematical proof can be classified into two categories, direct and indirect; and that there are different functions attributed to mathematical proof which are relevant depending on the field in which they are considered. Consequently, the three previous elements should be part of math teachers’ specialized knowledge to promote math proof in secondary education.</p> 2019-07-31T00:00:00-06:00 ##submission.copyrightStatement## https://www.revistas.una.ac.cr/index.php/uniciencia/article/view/11644 Evaluation of potential contamination of groundwater and spring protection areas of the Maravilla-Chiz and Quebrada Honda sub-basins, Cartago, Costa Rica 2019-08-27T09:46:40-06:00 Alicia Fonseca-Sánchez alicia.fonseca.sanchez@una.cr Helga Madrigal-Solís helga.madrigal.solis@una.cr Christian Núñez-Solís christian.nunez.solis@una.cr Hazel Calderón-Sánchez hazelcalderon@gmail.com Geannina Moraga-López geannina.moraga.lopez@una.cr Alicia Gómez-Cruz agomezcruz@gmail.com <p><span lang="en-US">The sub-basins of the Maravilla-Chiz and Quebrada Honda Rivers have an approximate area of 46.8 km</span><span class="CharOverride-1" lang="en-US">2</span><span lang="en-US">&nbsp;and are located in the eastern part of the Costa Rican metropolitan area, where agricultural and livestock productions are the main economic activity. The sub-basins supply the populations nearby with groundwater sources. The objective of the paper was to determine the possible groundwater contamination by assessing the state of the protection areas of springs used for public water supply. For such purposes, potential point, line, and diffuse sources of contamination were considered and classified according to the POSH (Pollutant Origin and its Surcharge Hydraulically) method. The protected area corresponded to a 200 m radius around the headwaters (Costa Rican Law 276). Results identified that 7% of the area showed diffuse sources of high potential generating pollutant load, due to the large quantities of pesticides used in greens and vegetables, while 55% presented a moderate potential in plots of sugarcane, coffee, and urban areas with no sanitary sewer. Half of the point sources found were classified as a high potential and 46% as moderate. Of the 252 line-kilometers corresponding to rivers, road network, and pipeline, 89% was classified as moderate potential, 10% as high, and 1% as reduced. Finally, the invasion of line and diffuse sources in the spring protection areas was confirmed; therefore, the local government is recommended to start a legal procedure to address the problem.</span></p> 2019-07-31T00:00:00-06:00 ##submission.copyrightStatement## https://www.revistas.una.ac.cr/index.php/uniciencia/article/view/11761 Understanding Space Weather: Solar Cycles and Magnetic Rossby Waves 2019-08-27T09:46:40-06:00 Xiomara Márquez-Artavia xiomara.marquez.artavia@una.cr <p>The objective of this investigation is to explore the relationship between slow and fast magnetic Rossby waves and certain observations of long-term solar activity (months, years, decades, …). This paper seeks to determine if the periods of these waves correspond to the values recorded for cycles such as the Rieger cycle and the Haly cycle, or otherwise to quasi-periodic outbursts and of flares and Coronal Mass Ejections. The study begins with a literature review and a summary of the results of a Ph.D. dissertation that completely solves the mathematical model analyzed; using the equations derived from this previous work, the periods of the waves are calculated and then compared to observations. The results of this comparison suggest that certain types of solar activity may be due to Rossby magnetic waves originating within the Sun, specifically in the tachocline. The slow magnetic Rossby waves are associated with long-term and very long-term cycles, while the fast magnetic Rossby waves are a plausible cause for cycles with periods of months or a few years. The study of magnetic Rossby waves and their properties will doubtlessly provide new insights into the origin and properties of the solar magnetic field.</p> 2019-07-31T00:00:00-06:00 ##submission.copyrightStatement## https://www.revistas.una.ac.cr/index.php/uniciencia/article/view/11762 College education of elementary school teachers: the case of mathematics 2019-08-27T09:46:40-06:00 Marianela Alpízar-Vargas marianela.alpizar.vargas@una.ac.cr Ana Lucía Alfaro-Arce ana.alfaro.arce@una.ac.cr <p>This article describes the curricula offered by state and private universities in Costa Rica to obtain a teaching degree in cycles I and II of elementary education. The study is qualitative and descriptive. Curricula from different universities were reviewed, and coordinators of related programs and math professors from those universities were interviewed. The analysis revealed a wide variety of study programs to train elementary school teachers with no general guidelines and little control. Therefore, there are no regulations in Costa Rica for these programs’ purposes, duration, content or teacher profile, which could affect math education in elementary schools since teachers come from programs with different emphasis</p> 2019-07-31T00:00:00-06:00 ##submission.copyrightStatement##