In Costa Rica, mangrove potential has not been studied from a biotechnological perspective, despite reports from other latitudes of promising fungi associated with these ecosystems, including biosurfactant potential. These molecules are primarily used in industry as emulsifiers; however, studies indicate their potential in healthcare, pharmaceutical, and agricultural applications. [Objective] This study aimed to screen and preliminarily identify fungal strains capable of producing biosurfactants by implementing a set of effective, low-cost, straightforward assays for future exploitation. [Methodology] Five fungal strains from the Manuel Antonio mangrove in Puntarenas, Costa Rica, were isolated, molecularly identified, and assessed for biosurfactant production utilizing the crude biosurfactant broth. The drop collapse test, oil displacement test, emulsification index, and hemolysis tests were assessed. [Results] The use of crude biosurfactant broth minimized the cost and time required for purifications, which enabled the reduction of screening time for all fermentations. Isolate MP4 displayed, overall and consistently, better performance than the other strains evaluated for growth and biosurfactant production assays, especially for the emulsification index and blood hemolysis test. ITS and LSU molecular markers were analyzed, and MP4 was taxonomically assigned as Trichoderma sp.; however, it was shown to be closely related to T. melanomagnum. [Conclusions] Results emphasize the unexplored potential of mangrove resources in Costa Rica for biosurfactant production, and although preliminary, they demonstrate the value of conducting future comprehensive studies to evaluate this fungal potential.
[Objective] Given the ease with which microplastics (MPs) are transported, ecosystems around the world are being polluted with these particles. Reports on the presence of MPs in marine organisms are alarming, but research on the presence of such particles in the terrestrial environment is still very scarce in Costa Rica, and even scarcer for the Central American region. Given this situation, it was considered urgent to carry out a multidisciplinary investigation to obtain information about MP contamination of animal tissues destined for human consumption. [Methodology] Samples of 20 livers from bovines and 18 from porcine, were purchased from local markets in 4 of the main meat-producing regions of the country. All samples were chemically digested with potassium hydroxide for the extraction of microplastic particles. [Results] Ninety percent of the bovine livers were positive for the presence of MPs, as were 83.3% of the porcine livers. Fibers and films, ranging from 220 & micro;m to 4.5 mm, most of which were blue-green in color, were found. [Conclusions] These findings provide information about the types of MPs that were present in the samples analyzed, but they do not aid in determining the exact origin of the particles and how they reached livers of the animals. Nonetheless, it is now clear that these pollutants are reaching human and animal populations, and since adverse effects have already been reported due to the presence of these particles in the human body, these results must be taken into account by healthcare professionals when considering any emerging diseases.
This study is part of a broader research project on algebraic thinking in early childhood and elementary education (www.pensamientoalgebraico.en). [Objective] The objective of this work is to identify the change perceived by 3-year-old children when solving generalization tasks that involve qualitative or quantitative changes. [Methodology] Ateaching experiment consisting of 4 worksessions with a group of 25 3-year-old children from a public school in Granada was designed and implemented.The perception of qualitative and quantitative change was investigated.The first session involved color and size as attributes; the second session included the function f(n)=n+1. The focus was on identifying relationships between variables and on the way children expressed these relationships through the changes that affect these variables. [Results] The children identified the qualitative change by saying that the colored object that entered the rocket changed color and came out gray, for example, they used expressions such as "the color is gone," "it comes out black," or "it comes out gray." In the case of quantitative change, they indicated that the ice cream that was inserted always came out with one more scoop than those that entered the machine, using statements such as "it comes out bigger," "it comes out higher," or "many come out." [Conclusion] Based on the statements given bythe children, it can be concluded thatthey identified the changes in color, size and increase.
[Objective] The competence to pose problems promotes a deep understanding of mathematical concepts and develops problem-solving skills in students. Therefore, teachers must have the competence to effectively pose and modify the problems they use in the instructional process to offer students better learning opportunities. This study aims to evaluate the development of problem-solving and problem-posing skills on statistical tables and the assignment of algebraic reasoning levels. [Methodology]As part of a training exercise, two problems related to statistical tables taken from textbooks were given to a sample of 66 prospective mathematics teachers.Their answers were evaluated through content analysis. [Results] Results revealed that prospective teachers correctly posed and solved problems involving statistical tables and demonstrated the use of advanced algebraic reasoning levels. However, limitations were observed in assigning algebraic reasoning levels to modified or self-created problems, particularly those focused on constructing different types of statistical tables. [Conclusions] Trainees adequately solved problems; however, they partially developed the competencies of problem-posing and assigning algebraic reasoning levels based on statistical tables. In conclusion, the development of these competencies must be reinforced in teacher training, given the relevance to their professional performance and student learning.
Objective: This study is aimed at identifying the economic and legal factors that have an impact on the profitability of installing small-scale commercial wind turbines at different locations in Costa Rica, to determine their economic viability. Methodology: Historical wind speed data from 36 meteorological stations of the Instituto Meteorologico Nacional de Costa Rica, recorded at 10 meters above the ground, was used and modeled at 15, 20, 25, and 30 meters above the ground. Using 18 histograms similar to the Weibull distribution, wind power generation was calculated using the power curves of three commercial wind turbines, estimating the annual energy production for each combination of location, turbine, and height. The best combinations were selected, and the expected economic savings were calculated using the average electricity tariff in the country. The economic evaluation included Net Present Value and Internal Rate of Return. Results: The analysis revealed that of the 36 locations evaluated, 18 could be modeled at different heights. Of these, nine locations had turbine and height combinations that were economically and legally viable, with maximum annual savings of USD 1,514. However, for nine additional locations, installation was not economically feasible due to the characteristics of wind resource and current cost of electricity. Conclusions: The profitability of small-scale wind turbines in Costa Rica is achieved at heights of 30 m in specific locations in which technical, economic, and regulatory factors align, enabling the extrapolation of these findings to support decentralized energy planning decisions.
[Objective] This study evaluates the processes of construction and argumentation of tables and graphs submitted by pre-service and in-service teachers. [Methodology] For this purpose, a mixed approach was used, predominantly focused on a quantitative inferential analysis. Information was obtained using an instrument with open questions related to the construction and justification of graphic representations associated with qualitative and quantitative discrete variables. The instrument was administered to a non-probabilistic sample of 102 subjects, of which 71 corresponded to pre-service primary education teachers and 31 to in-service primary education teachers in south-central Chile. [Results] In general, both groups correctly summarize the distribution according to the nature of the data; however, they make mistakes in their construction, such as labeling the axes according to the context of the problem. In addition, the arguments about the choice of graphical representation deviate from the theory. [Conclusions] Pre-service and in-service primary school teachers have not developed skills such as argumentation and transnumeration, which are characteristic of the statistical literacy and reasoning that would help them perform adequately in the school system.
[Objective] The study aimed to analyze the modeling process conducted by university students when solving a problem involving the notion of function optimization. [Methodology] Mathematical modeling is approached from the perspective known as models and modeling, utilizing the modeling cycles from Blum, Leiß, and Borromeo-Ferri, as well as the extended cycle for the use of digital technologies, to describe the processes students conduct during their resolution. The research design is an instrumental multiple case study. The paper reports the work of two second-semester students from the Business Administration program at a university in Lima, Peru, enrolled in the Calculus course during the first semester of 2022. Data was collected using worksheets, GeoGebra files, and semi-structured interviews. [Results] Results show that students developed skills in three areas: in the real world, by understanding that the cost of wiring varies according to the length and type of cable; in the mathematical world, by creating and using a mathematical model to optimize a function by applying prior knowledge on calculus; and in the computational world, by using GeoGebra to apply these concepts. [Conclusions] It is concluded that GeoGebra is a solid tool for developing modeling problems since its interface allows connecting the numerical, algebraic, geometric, and variational fields, providing a better interpretation of the phenomenon of change underlying an optimization problem.
[Objective] This paper aims to describe textbook tasks from the perspective of content analysis to demonstrate the relationship between the book and the curriculum in Costa Rica. [Methodology] This study is limited to the publishers Grupo Nación and Editorial Santillana; therefore, 88 tasks were selected from books from these publishers. A qualitative paradigm is used in combination with a descriptive approach. The bibliographic review conducted helps define the analysis categories that guide the data collection and the subsequent analysis. [Results] Some of the results helped to contrast the textbook proposal with the Ministry’s proposal. Both proposals strongly agree on the content of patterns. However, there were discrepancies in the use of mathematical concepts according to the modes of interpretation. The study revealed the absence of tasks enabling the creation or duplication of patterns or math tasks related to the application of mathematics in social or scientific environments. [Conclusions] This type of research highlights the importance of teacher training by analyzing tasks in response to current demands, having an impact both on teaching planning and on the skills that must be taught to students to achieve quality mathematics education. It is essential to consider, in teaching planning, those tasks that, according to the results, are absent from the textbook.
[Objective] The objective of this research is to identify the mental structures and mechanisms used by a group of Business Administration students to understand the solution set of a system of linear inequalities in two variables (SSSLI), as they establish Cartesian Connections. The theoretical foundations used are the APOS theory articulated with the concept of Cartesian Connection. [Methodology] This study is qualitative. For the design of the instrument, a preliminary genetic decomposition (PGD) was developed, and based on the PGD three tasks were designed. For data collection, these tasks were applied to a group of 19 students (between 18 and 22 years old). Later, the three participants who provided the most detailed answers were selected to conduct a semi-structured interview. [Results] The results showed that participants constructed the SSSLI Process by coordinating the solution set Process of the linear inequality in two variables (SSLI) with the set intersection Process. It was observed that participants associated the SSSLI with a polygon and did not consider it to be an empty, convex or bounded set. [Conclusions] It was concluded that those participants who constructed the action structure or a SSLI process showed the same type of structure in relation to SSSLI. New research is suggested that delves deeper into the mechanisms and mental structures described in this study, as well as into the design of teaching proposals that contribute to improving SSSLI learning.
[Objective] The objective of the study was to analyze and compare the level of didactic suitability of instructional processes related to the study of quadrilaterals, starting with the analysis of a primary education book that addresses the topic, followed by the analysis of two lessons actually implemented by teachers who used the book as a resource, examining their actions to evaluate whether or not they improved the process outlined in the book. [Methodology] After the level of didactic suitability of the book was determined, a case study was carried out with two primary school teachers (one novice and one expert) who used the same book in the fourth year of elementary school to teach the lessons on quadrilaterals. For the analysis, the didactic suitability indicators of a general analysis guide of instructional processes were adapted to the topic of quadrilaterals, to the educational level (elementary) and to the Costa Rican curriculum. [Results] The level of suitability of the instructional process outlined in the book was medium (on a high, medium or low scale), containing some weaknesses and mathematical errors. The instructional processes implemented by both teachers were less appropriate than the ones described in the book, although there were no significant differences. There were few actions implemented by the teachers that resulted in an improvement of the instructional process used in the book. [Conclusions] The levels of adequacy of the processes implemented by the teachers were below the level of the process outlined in the book, presenting errors and weaknesses specific to the book and amplifying them. It is necessary to provide opportunities for teachers to improve their ability to use the book critically as well as their didactic-mathematical knowledge. The indicators adapted can be used to support teachers in these tasks.
[Objective] The propagation method of plum trees is crucial for production success, as it likely influences plant compatibility and performance. The objective of this research was to evaluate two propagation systems of the ‘Reina Claudia’ plum tree variety, comparing bud grafting and cuttings, to identify the method most compatible with the variety. [Methodology] Since 2018, an experiment has been conducted in Sesquilé, Cundinamarca, to compare the two propagation methods of ‘Reina Claudia’ plum trees (Prunus domestica L.). The experiment followed a completely randomized design. One method involved bud grafting onto a ‘common white’ peach rootstock (Prunus persica L.), while the other used cuttings from the same plum variety. [Results] Significant differences were observed in the main branch diameter, with trees propagated by cuttings (TPC) reaching 31.62 mm, compared to 17.74 mm in those propagated by grafting (TPG). Water potential in TPC trees ranged from 0 to -107.25 kPa, while in TPG trees, it ranged from 0 to -58.25 kPa. Stomatal conductance values were higher in TPG (0 to 879 mmol m-2 s-1) than in TPC (149.0 to 761.31 mmol m-2 s-1). The propagation method influenced both water potential and chlorophyll content in the plum trees. [Conclusions] The TPC trees exhibited greater vegetative growth, including increased height, leaf area, crown diameter, and crown volume. However, TPG trees demonstrated greater precocity.
[Objective] The main objective of this research was to measure the impact on academic performance of a teaching proposal for mathematical modeling of functions using Brousseau’s theory of didactic situations. [Methodology] A quantitative study with a pre-experimental design was conducted with a sample of 22 high school students belonging to the Remigio Crespo Toral Educational Unit (Ecuador). Previously, the participants followed a conventional study routine on the topics of function modeling. A pretest was then administered to evaluate the group’s academic performance. Subsequently, eight work sessions were conducted during which the didactic situations were implemented. Finally, a posttest was administered to evaluate the results after the intervention. [Results] The results of a descriptive analysis of the grades showed an 87% improvement in posttest scores, and the results of a student’s t-test analysis showed a significant difference between the pretest and posttest scores (p-value < 0.05). Furthermore, it was confirmed that the theory of didactic situations is compatible with the modeling cycle by strengthening various modeling competencies, such as the use of graphs and algebraic language. [Conclusions] It was shown that mathematical modelling using didactic situations significantly improved academic performance.
[Objective] This study aimed to deepen the understanding of anxiety associated with teaching mathematics among university students in Primary Education programs in Costa Rica. [Methodology] A descriptive quantitative study was conducted with students from the three public universities offering the Primary Education program in Costa Rica. The sample consisted of 223 pre-service primary teachers. The significance of 11 sociodemographic variables regarding anxiety levels towards teaching mathematics was investigated. Differences between groups were analyzed using t-tests for dichotomous variables and one-way ANOVA for the remaining variables. Data was analyzed with SPSS, and results were considered significant if p < 0.05. [Results] Most participants exhibited a medium level of anxiety regarding the teaching of mathematics. Significant differences were found in academic performance for the general construct and for the dimensions of content knowledge, self-confidence, and attitudes toward teaching mathematics. Significant differences were also observed according to employment status in the content knowledge dimension, the grade they least preferred to teach in that same dimension, and age in the didactic knowledge dimension. [Conclusions] Participants with lower academic performance showed higher levels of anxiety overall. In addition, participants who avoided teaching sixth grade and older subjects exhibited higher levels of anxiety related to their content knowledge and didactic knowledge, respectively.
Proportional reasoning is considered a key element in probabilistic reasoning. Various studies have suggested that insufficient proportional reasoning may be the cause of many errors made by students when dealing with probability problems. [Objective] The aim of this study is to identify the proportional reasoning used by sixth grade students (11-12 years old) when solving sample space quantification and probability comparison tasks. [Methodology] Through an exploratory qualitative approach, the responses of 47 Spanish students from a public school were analyzed in relation to two problems: one focused on comparing probabilities (ratio comparison), and the other on determining the composition of a box to generate equal probabilities (proportional distribution). The analysis of the solutions using semiotic functions allows identification of relationships between objects involved in the tasks and the characteristic elements of proportional reasoning, facilitating interpretation of students’ errors. [Results] The results show that the students struggled to select the box with the highest probability of success, which indicates insufficient proportional reasoning. However, most students were able to correctly determine the composition of a box needed to maintain a given probability, whereas few could justify their reasoning based on probability or proportionality. [Conclusions] The results contrast with previous research findings and show previously unidentified difficulties in solving proportional distribution problems in a probabilistic or arithmetic context.
Recent studies on the development of strategies and proposals to enhance geometric thinking reflect the advancement of Geometry Education as a research field. The identification of key areas of interest and thematic lines also helps to reveal significant gaps that hinder improvements in the teaching and learning of geometry. [Objective] This article is intended to carry out an exploratory systematic review of literature published in high-impact journals in Ibero-America to identify the main research focus in geometry education during the first decades of the 21st century. [Methodology] The review is organized into three phases: selection, descriptive analysis, and interpretation. In the first phase, the selected articles are characterized according to variables such as type of study, educational level, participant profile, and implementation modality. In the second phase, nine emerging categories are identified and subsequently organized into four overarching analytical categories. [Results] The findings partially align with those reported in other systematic reviews, highlighting interest in the design and use of tasks, mathematical processes, the role of technology, and the analysis of errors and learning obstacles. However, the review also reveals a limited number of studies addressing mathematical connections, teacher-student interaction, the impact of contextual conditions, and the use of evaluation results to inform pedagogical decision-making. [Conclusions] This review contributes to updating the landscape of research in geometry education, identifying consolidated lines of inquiry and highlighting strategic gaps to guide future research agendas.
[Objective] The objective of the research was to determine the mathematical modeling competencies shown by a group of prospective teachers in Mathematics Teaching, in their fourth year of studies at the Universidad Nacional. [Methodology] For this purpose, a qualitative research was conducted with 20 prospective mathematics teachers during the first half of 2022, when they were required to solve a series of problems as part of a training program in mathematical modeling. The work done by the participants on two specific problems is presented. [Results] The participating prospective teachers demonstrated competencies in solving mathematical modeling problems when the situation presented has the necessary data and its solution requires a specific procedure. In situations that involved conducting research to gather additional information or data, and making assumptions, among other things, which could imply different solutions, the participants had difficulties in solving the problems. [Conclusions] The participants demonstrated their ability to handle and make sense of relevant data for solving mathematical modeling problems. However, when they needed to conduct research to gather additional information or data, they were unable to identify which data should be included in the problem-solving process. Their ability to search for information, connect a mathematical model with another problem situation or a known model, or validate the solution obtained for a problem, was limited. The results obtained could indicate that it is necessary to emphasize these types of activities in the teacher training programs, for their use as a teaching strategy in their professional practice.
[Objective] This study is intended to design and validate instruments for assessing mathematical errors, math anxiety, and visuospatial abilities in prospective mathematics teachers, to generate information that relates these variables to learning quality, from a gender perspective. [Methodology] This is a quantitative, non-experimental study with a descriptive, correlational scope and a cross-sectional design. The process included three stages: first, the design of two preliminary instruments—one with 32 items to measure math anxiety and another with 52 items to assess mathematical difficulties, errors, and spatial abilities. In the second stage the instruments were validated by experts, and finally, a pilot test was conducted, after which the items were revised and improved. [Results] The process resulted in three instruments: one to measure math anxiety (20 items, reliability = 0.825), one to assess mathematical errors and difficulties (41 items, reliability = 0.973), and another to measure visuospatial ability (9 items, reliability = 0.982). [Conclusions] The instruments developed allow for valid and reliable diagnosis of mathematical errors, math anxiety, and visuospatial abilities in initial teacher education. This information supports the development of equitable pedagogical strategies by addressing variables that affect performance and gender gaps, and opens new lines of research on their impact on teacher training trajectories.
[Objective] Currently, individuals must understand statistical data to form critical opinions and make informed decisions. For this reason, various organizations and authors have pointed out the need to begin to develop gradually, from an early age, data reading skills and their graphic representation, an aspect that has been progressively incorporated into the mathematics curricula of various countries. In this context, this study aims to conduct a systematic review of research articles published over the last decade (2014-2023) that have analyzed the knowledge of statistical graphics among infant and primary school students (4 to 12 years old). [Methodology] Based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement, after applying the exclusion criteria, 12 articles published in the Web of Science, Scopus, and SciELO databases were analyzed. [Results] The main findings show: a) a low number of articles related to students in the first years of school, predominantly research focused on primary education; b) the most researched topic is reading and interpretation of graphs. [Conclusions] New studies should be promoted to more precisely identify the different types of knowledge regarding statistical graphics that students can acquire according to their age (4-12 years). This will help in designing and implementing teaching practices aimed at fostering optimal graphic comprehension.
[Objective] Assess whether low protein intake is related to the development of sarcopenia in older adults. [Methods] This paper included primary studies focused on the relationship between protein intake and sarcopenia or its individual components (low muscle mass and strength and lower physical performance) in adults older than 60 years. The following studies were excluded: projects with no research design, studies with other nutritional interventions, and studies in older individuals with a sarcopenia diagnosis different than the one defined by the European Working Group on Sarcopenia in the Older People, with other comorbidities, or with pharmacological treatment. A systematic search was conducted in four databases, utilizing keywords in combination with Boolean operators. [Results] Out of the 15 studies included, 6 cross-sectional studies and 1 cohort study identified a significant association between low protein intake and an increased risk of sarcopenia, while 3 studies reported no significant association. Furthermore, 3 randomized controlled trials (RCTs) found no significant improvements in the sarcopenia-related components for the protein-supplemented intervention group compared to the control group. Only one randomized controlled study and one secondary data analysis study demonstrated significant improvements in muscle mass within the intervention group. [Conclusions] Low protein intake was significantly associated with a greater development of sarcopenia and lower muscle mass. This association was not observed on individual sarcopenia-related components.
[Objective] The objective was to estimate the carbon stock and its spatial distribution in soils of the Zanja Honda micro-watershed (Ibagué, Colombia). [Methodology] Hydrological Response Units were delineated, considering land cover, soil units, and the range of slopes. Based on the representativeness of these hydrological units, 46 sampling sites were identified. After locating sampling sites in the field, the following parameters were determined at each site: thickness of horizons, bulk density (core method), rock fragment content by weight and volume, and organic carbon concentration using the wet oxidation method. [Results] The most significant magnitudes in organic carbon content and soil organic carbon stock generally occur in the lower part of the micro-watershed (0.05 Mg ha-1); while the high slope areas in the middle-upper part present lower magnitudes of these variables (0.002 Mg ha-1). The soils studied store a total of 6736.3 Mg of organic carbon, which is generally stored in the first 0.3 m of the soil profile. [Conclusions] Micro-watershed soils exhibited lower organic carbon stocks compared to other studies conducted in the area, with carbon stocks primarily occurring in low areas with lower inclinations. This suggests that topographic variables play a significant role in determining carbon stocks in these soils.
