Subjects -> MATHEMATICS (Total: 1013 journals)
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    - MATHEMATICS (714 journals)
    - MATHEMATICS (GENERAL) (45 journals)
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MATHEMATICS (714 journals)            First | 1 2 3 4     

Showing 601 - 538 of 538 Journals sorted alphabetically
Results in Mathematics     Hybrid Journal  
Results in Nonlinear Analysis     Open Access  
Review of Symbolic Logic     Full-text available via subscription   (Followers: 2)
Reviews in Mathematical Physics     Hybrid Journal   (Followers: 1)
Revista Baiana de Educação Matemática     Open Access  
Revista Bases de la Ciencia     Open Access  
Revista BoEM - Boletim online de Educação Matemática     Open Access  
Revista Colombiana de Matemáticas     Open Access   (Followers: 1)
Revista de Ciencias     Open Access  
Revista de Educación Matemática     Open Access  
Revista de la Escuela de Perfeccionamiento en Investigación Operativa     Open Access  
Revista de la Real Academia de Ciencias Exactas, Fisicas y Naturales. Serie A. Matematicas     Partially Free  
Revista de Matemática : Teoría y Aplicaciones     Open Access   (Followers: 1)
Revista Digital: Matemática, Educación e Internet     Open Access  
Revista Electrónica de Conocimientos, Saberes y Prácticas     Open Access  
Revista Integración : Temas de Matemáticas     Open Access  
Revista Internacional de Sistemas     Open Access  
Revista Latinoamericana de Etnomatemática     Open Access  
Revista Latinoamericana de Investigación en Matemática Educativa     Open Access  
Revista Matemática Complutense     Hybrid Journal  
Revista REAMEC : Rede Amazônica de Educação em Ciências e Matemática     Open Access  
Revista SIGMA     Open Access  
Ricerche di Matematica     Hybrid Journal  
RMS : Research in Mathematics & Statistics     Open Access  
Royal Society Open Science     Open Access   (Followers: 7)
Russian Journal of Mathematical Physics     Full-text available via subscription  
Russian Mathematics     Hybrid Journal  
Sahand Communications in Mathematical Analysis     Open Access  
Sampling Theory, Signal Processing, and Data Analysis     Hybrid Journal  
São Paulo Journal of Mathematical Sciences     Hybrid Journal  
Science China Mathematics     Hybrid Journal   (Followers: 1)
Science Progress     Full-text available via subscription   (Followers: 1)
Sciences & Technologie A : sciences exactes     Open Access  
Selecta Mathematica     Hybrid Journal   (Followers: 1)
SeMA Journal     Hybrid Journal  
Semigroup Forum     Hybrid Journal   (Followers: 1)
Set-Valued and Variational Analysis     Hybrid Journal  
SIAM Journal on Applied Mathematics     Hybrid Journal   (Followers: 11)
SIAM Journal on Computing     Hybrid Journal   (Followers: 11)
SIAM Journal on Control and Optimization     Hybrid Journal   (Followers: 18)
SIAM Journal on Discrete Mathematics     Hybrid Journal   (Followers: 8)
SIAM Journal on Financial Mathematics     Hybrid Journal   (Followers: 3)
SIAM Journal on Mathematics of Data Science     Hybrid Journal   (Followers: 1)
SIAM Journal on Matrix Analysis and Applications     Hybrid Journal   (Followers: 3)
SIAM Journal on Optimization     Hybrid Journal   (Followers: 12)
Siberian Advances in Mathematics     Hybrid Journal  
Siberian Mathematical Journal     Hybrid Journal  
Sigmae     Open Access  
SILICON     Hybrid Journal  
SN Partial Differential Equations and Applications     Hybrid Journal  
Soft Computing     Hybrid Journal   (Followers: 7)
Statistics and Computing     Hybrid Journal   (Followers: 13)
Stochastic Analysis and Applications     Hybrid Journal   (Followers: 2)
Stochastic Partial Differential Equations : Analysis and Computations     Hybrid Journal   (Followers: 1)
Stochastic Processes and their Applications     Hybrid Journal   (Followers: 5)
Stochastics and Dynamics     Hybrid Journal  
Studia Scientiarum Mathematicarum Hungarica     Full-text available via subscription   (Followers: 1)
Studia Universitatis Babeș-Bolyai Informatica     Open Access  
Studies In Applied Mathematics     Hybrid Journal   (Followers: 1)
Studies in Mathematical Sciences     Open Access   (Followers: 1)
Superficies y vacio     Open Access  
Suska Journal of Mathematics Education     Open Access   (Followers: 1)
Swiss Journal of Geosciences     Hybrid Journal   (Followers: 1)
Synthesis Lectures on Algorithms and Software in Engineering     Full-text available via subscription   (Followers: 2)
Synthesis Lectures on Mathematics and Statistics     Full-text available via subscription   (Followers: 1)
Tamkang Journal of Mathematics     Open Access  
Tatra Mountains Mathematical Publications     Open Access  
Teaching Mathematics     Full-text available via subscription   (Followers: 10)
Teaching Mathematics and its Applications: An International Journal of the IMA     Hybrid Journal   (Followers: 4)
Teaching Statistics     Hybrid Journal   (Followers: 8)
Technometrics     Full-text available via subscription   (Followers: 8)
The Journal of Supercomputing     Hybrid Journal   (Followers: 1)
The Mathematica journal     Open Access  
The Mathematical Gazette     Full-text available via subscription   (Followers: 1)
The Mathematical Intelligencer     Hybrid Journal  
The Ramanujan Journal     Hybrid Journal  
The VLDB Journal     Hybrid Journal   (Followers: 2)
Theoretical and Mathematical Physics     Hybrid Journal   (Followers: 7)
Theory and Applications of Graphs     Open Access  
Topological Methods in Nonlinear Analysis     Full-text available via subscription  
Transactions of the London Mathematical Society     Open Access   (Followers: 1)
Transformation Groups     Hybrid Journal  
Turkish Journal of Mathematics     Open Access  
Ukrainian Mathematical Journal     Hybrid Journal  
Uniciencia     Open Access  
Uniform Distribution Theory     Open Access  
Unisda Journal of Mathematics and Computer Science     Open Access  
Unnes Journal of Mathematics     Open Access   (Followers: 2)
Unnes Journal of Mathematics Education     Open Access   (Followers: 2)
Unnes Journal of Mathematics Education Research     Open Access   (Followers: 1)
Ural Mathematical Journal     Open Access  
Vestnik Samarskogo Gosudarstvennogo Tekhnicheskogo Universiteta. Seriya Fiziko-Matematicheskie Nauki     Open Access  
Vestnik St. Petersburg University: Mathematics     Hybrid Journal  
VFAST Transactions on Mathematics     Open Access   (Followers: 1)
Vietnam Journal of Mathematics     Hybrid Journal  
Vinculum     Full-text available via subscription  
Visnyk of V. N. Karazin Kharkiv National University. Ser. Mathematics, Applied Mathematics and Mechanics     Open Access   (Followers: 1)
Water SA     Open Access   (Followers: 2)
Water Waves     Hybrid Journal  
Zamm-Zeitschrift Fuer Angewandte Mathematik Und Mechanik     Hybrid Journal   (Followers: 1)
ZDM     Hybrid Journal   (Followers: 2)
Zeitschrift für angewandte Mathematik und Physik     Hybrid Journal   (Followers: 2)
Zeitschrift fur Energiewirtschaft     Hybrid Journal  
Zetetike     Open Access  

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Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1011-0275 - ISSN (Online) 2215-3470
Published by Universidad Nacional Costa Rica Homepage  [25 journals]
  • An Efficient Convolutional Neural Network to Detect and Count Blood Cells

    • Authors: Rakesh Chandra Joshi, Saumya Yadav, Malay Kishore Dutta, Carlos M. Travieso-González
      Pages: 1 - 11
      Abstract: Blood cell analysis is an important part of the health and immunity assessment. There are three major components of the blood: red blood cells, white blood cells, and platelets. The count and density of these blood cells are used to find multiple disorders like blood infections (anemia, leukemia, among others). Traditional methods are time-consuming, and the test cost is high. Thus, it arises the need for automated methods that can detect different kinds of blood cells and count the number of cells. A convolutional neural network-based framework is proposed for detecting and counting the cells. The neural network is trained for the multiple iterations, and a model having lower validation loss is saved. The experiments are done to analyze the performance of the detection system and results with high accuracy in the counting of the cells. The mean average precision is achieved when compared to ground truth provided to respective labels. The value of the average precision is found to be ranging from 70% to 99.1%, with a mean average precision value of 85.35%. The proposed framework had much less time complexity: it took only 0.111 seconds to process an image frame with dimensions of 640×480 pixels. The system can also be implemented in low-cost, single-board computers for rapid prototyping. The efficiency of the proposed framework to identify and count different blood cells can be utilized to assist medical professionals in finding disorders and making decisions based on the obtained report.
      PubDate: 2022-03-30
      DOI: 10.15359/ru.36-1.28
      Issue No: Vol. 36, No. 1 (2022)
  • Automated Quantification of Ki-67 on Gastric Epithelial Tissue based on
           Cell Nuclei Area Ratio

    • Authors: Austin Blanco-Solano, Francisco Siles Canales, Warner Alpízar-Alpízar
      Pages: 1 - 9
      Abstract: The objective was to develop an automated algorithm for the estimation of a protein (Ki-67) index based on cell nuclei area ratio of gastric epithelial tissue cells; for this purpose, digital histopathology images were used. An expert manually annotated each region of interest of the images. A proportion of Ki-67 positive and negative cells within that region was used to obtain the color distribution of the corresponding pixels. The histogram of each color distribution was modeled as a Gaussian and, later, thresholded for segmentation and classification. Finally, the Ki-67 index was estimated as the ratio between the segmented positive area of the nuclei divided by the total area of the positive and negative nuclei. The automated method has a strong correlation of 0.725 and a root mean square error of 0.293 when compared to the manual method, which gives certainty that the automated method can be used to analyze the proliferation rate. Furthermore, compared to manual classification, the presented method automatically classifies every image in the same Ki-67 category: low, intermediate, and high. Despite the small sample size, the utility of the presented method was demonstrated. However, the low number of scored images did not allow for thoroughly sampling the ranges of pixel values and intensities observed by pathologists, which will be addressed in future work.
      PubDate: 2022-03-30
      DOI: 10.15359/ru.36-1.29
      Issue No: Vol. 36, No. 1 (2022)
  • Pros and Cons of Computer-Assisted Rehabilitation

    • Authors: Norbert Ferenčík, Radovan Hudák, Miroslav Kohan, Viktória Rajťúková
      Pages: 1 - 7
      Abstract: This article summarized the knowledge obtained from exercises with patients using computer-assisted rehabilitation. Working with a wide base of healthy individuals and patients with various problems yielded the results to summarize. This work utilized several rehabilitation devices using computer games and uncovered positive and negative aspects of contemporary rehabilitation procedures. we conclude in this research computer-assisted rehabilitation is the future of modern rehabilitation, so it is necessary to know all factors affecting patients’ health.
      PubDate: 2022-03-30
      DOI: 10.15359/ru.36-1.27
      Issue No: Vol. 36, No. 1 (2022)
  • Surface water quality and socio-environmental pressures in the upper
           microbasin of the Poás river

    • Authors: Kelvin Arce-Villalobos, Rolando Sánchez-Gutiérrez, Jacqueline Centeno-Morales, Rolando Marín-León, Jorengeth Abad Rodríguez-Rodríguez
      Pages: 1 - 23
      Abstract: The objective of this research was to determine the quality of surface water in the upper part of the Poás river micro basin and the main socio-environmental pressures that may be related to current quality indices. An exploratory study with a quantitative approach was carried out in which the main socio-environmental pressures experienced by the water resource in the area were identified, while the quality of the surface water was determined based on physical, chemical, and microbiological indicators, as well as the application of two quality indices. Six socio-environmental pressures with a negative impact on the resource were found and related to specific actions carried out in homes and other socio-economic activities. Despite the fact that the evidence showed overall compliance between the analyzed parameters and quality criteria used nationally and internationally, the indices revealed incipient contamination levels, as well as good and medium quality. Statistically, it was found that water quality of the micro-basin does not vary spatially; however, it does vary temporarily due to the incidence of rainfall patterns in the area. This finding, along with the determination of significant correlations between the monitored parameters, contributed to the recognition that the sites monitored in the rainy season have a stronger relationship with parameters associated with organic pollution linked to runoff and wastewater discharge processes. Therefore, it is necessary to coordinate efforts that guarantee sustainability of the micro basin that improve the local sanitary infrastructure, strengthen water management processes, and are focused on the establishment of a monitoring network within a reference framework oriented towards basins.
      PubDate: 2022-03-10
      DOI: 10.15359/ru.36-1.24
      Issue No: Vol. 36, No. 1 (2022)
  • Obtaining leveled heights by GPS leveling. Case study: Morona –

    • Authors: Iván Fernando Palacios-Orejuela, Karol Dennise Arellano-Pérez
      Pages: 1 - 13
      Abstract: The aim of the study was to demonstrate the applicability of GPS leveling to obtain accurate leveled heights for engineering purposes, in the canton of Morona, Ecuador. Two working scales were evaluated: cantonal (macro) and urban (micro), where the known vertices from which the height value was determined were points that belong to the local geodesic network of the canton. Based on the analysis of the geoid undulation gradient, 5 homogeneous zones of the gradient variation were defined; GPS leveling was applied in the two zones (zone 4 and 5) that had geodesic vertices and that also cover a larger area of the canton. The geoid undulation gradient values in the study area were highly variable, with errors of up to 24 mm/km. At the cantonal scale, errors were reached between 12.19 cm - 1.27 cm at 30 Km - 5.1 Km in zone 4, and 38.48 cm - 8.33 cm at 13 Km - 2.7 Km in zone 5, while on an urban scale, errors of 2.48 cm - 0.14 cm were found at 1.07 Km - 0.19 Km, respectively. Using GPS leveling, useful results are obtained for engineering jobs and geoscience jobs in general, that require the determination of leveled heights quickly and accurately. For the correct application of this technique, two determinants must be considered: the baseline distance and the geoid undulation gradient.
      PubDate: 2022-03-10
      DOI: 10.15359/ru.36-1.26
      Issue No: Vol. 36, No. 1 (2022)
  • Inferential reasoning of high school mathematics teachers about t-Student

    • Authors: Jesús Guadalupe Lugo-Armenta, Luis Roberto Pino-Fan
      Pages: 1 - 29
      Abstract: One of the topics that have been deeply studied in Statistical Education is that of how to promote formal inferential reasoning (FIR) based on the results of informal inferential reasoning (IIR). However, it is still necessary to have proposals to explore and progressively develop the inferential reasoning of students and teachers from IIR to FIR. In this context, this article seeks to characterize the inferential reasoning displayed by high school mathematics teachers in the practices they developed for solving problems about Student’s t statistic. To do this, we use theoretical and methodological notions introduced by the Onto-Semiotic Approach (OSA) to mathematical knowledge and instruction, among which are the notion of mathematical practice, mathematical object and the theoretical proposal of progressive levels of inferential reasoning about the Student’s t statistic. The subjects who participated in this qualitative study were 59 teachers in training from Costa Rica and 22 practicing teachers from Chile. The practices developed by the pre-service teachers and the practicing teachers were found to have similar elements (representations, concepts/definitions, properties, procedures, arguments). The principal conclusion of this investigation was that the proposal of inferential reasoning levels about Student’s t statistic proved to be a useful predictor of the practices developed by the teachers, making it possible to distinguish characteristic elements of each level of inferential reasoning.
      PubDate: 2022-03-10
      DOI: 10.15359/ru.36-1.25
      Issue No: Vol. 36, No. 1 (2022)
  • Distribution, richness, and molecular identification of spider crabs
           (Brachyura: Majoidea: Mithracidae) from Costa Rica

    • Authors: Carolina Sancho-Blanco, Luis E. Salas-Arce, Jorge Alfaro-Montoya, Rita Vargas-Castillo, Antonio Baeza, Rodolfo Umaña-Castro
      Pages: 1 - 19
      Abstract: The objective of this study was to determine the distribution, richness, and molecular identification of spider crabs in the Costa Rican Pacific and Caribbean coasts. Distribution maps were created for species of the Mithracidae family on the Caribbean and Pacific coasts of Costa Rica, based on exploratory samplings and spatio-temporal records of collections (1960 to 2016) provided by the Universidad de Costa Rica’s Museum of Zoology. In addition, phylogenetic relationships were explored using a multigene concatenated phylogenetic tree based on mitochondrial and nuclear gene fragments. Historical records reveal the presence of 24 species of mithracid crabs and their geographic distribution in the Pacific and Caribbean of Costa Rica, including islands on the continental and oceanic shelf. Molecular analyses confirm sister relationships between the clades Ala-Maguimithrax, Omalacantha-Microphyrs, Omalacantha+Microphyrs-Teleophrys, and a well-supported clade of species belonging to the genus Mithraculus. However, our concatenated molecular data set suggests a monophyletic relationship between Thoe, Petramithrax, and Hemus, differing from what was previously reported. The results obtained in this study will help in the development of strategies for the environmental protection of these marine resources, by providing a baseline for monitoring environmental degradation and destruction of habitats used by spider crabs on the coasts of Costa Rica. Furthermore, the molecular information obtained in this study will help future studies focusing on understanding the population genetics, phylogeography, regional gene flow, and divergence among species between the Caribbean and Pacific coast.
      PubDate: 2022-02-14
      DOI: 10.15359/ru.36-1.18
      Issue No: Vol. 36, No. 1 (2022)
  • Tectona grandis L.f. clonal selection for the dry Pacific zone of Costa

    • Authors: Yorleny Badilla-Valverde, Olman Murillo-Gamboa
      Pages: 1 - 17
      Abstract: Teak has the highest value of any commercially planted tree species in the tropics. The tree improvement international cooperative GENFORES, established in Costa Rica, has led breeding programs with this tree species in Latin America. This investigation was undertaken with the objective of selecting the clones which are best adapted to the dry Pacific zone of Costa Rica, as well as for other dry regions in the tropics. Research was carried out in Nicoya, in the province of Guanacaste (in the northern Pacific region of Costa Rica), where 31 genotypes were evaluated for 13 continuous years, in terms of diameter growth, commercial volume, and stem quality. Genetic parameters were obtained using Selegen-REML/BLUP software, as were selection rankings and estimated genetic gain. The highest values for individual heritability and mean clonal heritability for diameter (h2g = 0.12 and h2mc = 0.82), and for commercial volume (h2g = 0.075 and h2mc = 0.74) were obtained for trees that were 8.9 years old. Commercial plantations established with the best 10 clones, with an age of 12.9 years, may attain a commercial volume of 0.88 m3 per tree, corresponding to a genetic gain of 11% with respect to the best available seed source from a seed orchard, while diameter would reach 28 cm at the same age. These results allow a reduction of approximately two years of the age at which teak can be harvested in the dry Pacific zone of the country.
      PubDate: 2022-02-14
      DOI: 10.15359/ru.36-1.19
      Issue No: Vol. 36, No. 1 (2022)
  • Tooth whitening in conventional orthodontic patients: a systematic review

    • Authors: Stefanía Hernández-Viana, Miguel Fernando Niño, Felipe Augusto Restrepo, Javier Enrique Botero
      Pages: 1 - 18
      Abstract: This systematic review aimed to identify and critically evaluate the available evidence of the appropriate moment to perform tooth whitening in conventional orthodontic patients. A systematic review in MEDLINE and SciELO databases from inception to February 2021 was carried out by two independent reviewers. Randomized clinical trials, non-randomized clinical trials, case-control, cohort, cross-sectional, case-series and reviews that focused on the application of tooth whitening during or after orthodontic treatment were considered for inclusion. The primary outcome was defined as tooth whitening during/after orthodontic treatment. The secondary outcome included the time in days after bracket debonding in which tooth whitening was performed. Risk of bias analysis was performed for each study and the findings were synthesized in a narrative summary. A total of 4 randomized clinical trials, 1 non-randomized clinical trial and 3 reviews were included in the qualitative synthesis. One study performed tooth whitening during, and three studies after orthodontic treatment. One study compared tooth whitening during and after orthodontic treatment. The time after which tooth whitening was applied following bracket debonding ranged from 7 to 90 days with a mean value of 40.2 days. All studies reported satisfactory improvements in tooth color shade during or after orthodontic treatment independent of the protocol. Low quality evidence suggests that the appropriate moment to perform tooth whitening in conventional orthodontic patients is after brackets removal with a waiting period of at least 30 days. There is not adequate evidence to support tooth whitening during conventional orthodontic treatment.
      PubDate: 2022-02-14
      DOI: 10.15359/ru.36-1.21
      Issue No: Vol. 36, No. 1 (2022)
  • Mathematical Creative Thinking Ability and Self-Efficacy: A Mixed-Methods
           Study involving Indonesian Students

    • Authors: Sri Rahayuningsih, Muhammad Nurhusain, Nenny Indrawati
      Pages: 1 - 16
      Abstract: With regard to creativity in mathematics, scholars tend to focus on the logical realm, which includes fluency, flexibility, and originality while overlooking the value of the affective domain, which includes self-efficacy, beliefs, and attitudes. The objectives of this study were 1) to investigate the extent to which self-efficacy affects students’ mathematical creative thinking ability; and 2) to determine the characteristics of students with high mathematical creative thinking ability and high self-efficacy. A mixed-method approach, that combined semi-structured interviews, and correlation analysis was employed to investigate the effect of self-efficacy on students’ mathematical creative thinking ability. The participants of the study were selected from junior high schools (JHS) in the city of Makassar. Ninety-six students (42 boys and 54 girls, aged 14 years old) completed a questionnaire assessing their mathematics self-efficacy. In general, the results proved that self-efficacy had an effect on JHS students’ mathematical creative thinking ability. This study also revealed that students with high self-efficacy are more likely to possess high mathematical creative thinking ability and vice versa. The characteristics of students with high mathematical creative thinking ability and high self-efficacy include excessive anxiety, reliance on key experiences, such as the ability to generate ideas (cognitive novelty), the ability to propose various solutions (cognitive variety), and the ability to change perceptions (cognitive framing).
      PubDate: 2022-02-14
      DOI: 10.15359/ru.36-1.20
      Issue No: Vol. 36, No. 1 (2022)
  • Literacy and probabilistic thinking in pre-service and in service
           mathematics teachers

    • Authors: Francisco Rodríguez-Alveal, Danilo Díaz-Levicoy, Maitere Aguerrea
      Pages: 1 - 18
      Abstract: The objective of this study is to characterize the literacy and probabilistic thinking skills that trainee and currently active mathematics teachers use when faced with real-world problems, in which uncertainty plays a role. A qualitative methodology was used, applying a case study design and the content analysis method. As a technique to obtain information, an open-question instrument was prepared based on two problem situations, which the participants were asked to complete. The 55 participants were selected through intentional or disposition sampling, 26 of whom were actively teaching, and 29 of whom were trainee teachers. Among the main results, it is worth noting that all teachers that participated in the study, both active and trainees, have not developed probabilistic skills that allow them to consider problems from the intuitive, classical and frequency perspectives, essentially resorting to the classical meaning of probability. In addition, there is little evidence of the development of conceptual and argumentative skills that allow comparing empirical and theoretical results. In conclusion, it was observed that both active and trainee teachers have not developed literacy skills and probabilistic thinking which would allow a way of teaching probability that goes beyond the purely algorithmic, promoting learning environments for the probabilistic literacy of students during their school years.
      PubDate: 2022-02-14
      DOI: 10.15359/ru.36-1.22
      Issue No: Vol. 36, No. 1 (2022)
  • Emotions associated with the process of construction the parallelepiped

    • Authors: Fabricio Vladimir Vinces-Vinces, Juan David Giraldo-Rojas, Marcela Cecilia Parraguez-González, Luis Albeiro Zabala-Jaramillo
      Pages: 1 - 21
      Abstract: This study analyzes the emotions of students between 14 and 17 years of age when they autonomously construct a rectangular box in 2D and 3D that represents the volume of a parallelepiped, using Cabri II Plus software. The methodology was based on frequency analysis using heat maps constructed with the Python computing tool. Using non-probabilistic sampling, and with the prior informed consent of their legal representatives, 34 ninth grade elementary school students were selected from a public educational institution in the city of Medellin, Colombia, of whom 28 participated in this study. Emotion was considered from a comprehensive point of view, taking into account its evolutionary, physiological-neural, cognitive, volitional and expressive aspects. FaceReader software, a specialized tool for detecting facial expressions, was used to capture these emotions. The results showed that, due to difficulties in the construction process, emotions such as sadness, anger, neutrality, fear, disgust and surprise were experienced. In the population studied, a correlation between emotional processing capacity and cognitive processing was detected. It was concluded that, when faced with difficulties in geometric construction that required drawing parallel lines and perpendicular lines, the difference between one point of intersection and another, and the relationship between the area or volume of a parallelepiped in 2D and 3D, negative emotions associated with the lack of mastery of these concepts emerged which, if students cannot exercise self control, can inhibit their cognitive processing, blocking their mental activities and leading them to abandon the task.
      PubDate: 2022-02-14
      DOI: 10.15359/ru.36-1.23
      Issue No: Vol. 36, No. 1 (2022)
  • Waste management: a study on generating organic fertilizer from oil and
           grease trap systems

    • Authors: Julián Rojas-Vargas, José Mora-Barrantes, Pablo Herrera-Vargas, Vinicio Arias-Zuñiga
      Pages: 1 - 15
      Abstract: The grease and oil trap systems (GOTS) of four university food service establishments (FSE) were assessed and treated to evaluate the potential use of the sludge collected to produce compost. The sludge collected from each FSE was kept in a drying bed for 30 days (SDB), during which time calcium oxide was frequently added for stabilization. The sludge deposited monthly was reduced to half after the drying process and was then deposited in a composter and mixed for a period of 22 days with constant agitation. The compost obtained was treated with degrading enzymes and was denominated enzymatic composting (EC), while the remaining compost was not treated with enzyme and was denominated non-enzymatic compost (NEC). The total composting cycle of the sludge lasted 83 days, during which time various physical and chemical analyzes were conducted in the three types of substrates (SDB, NEC, and EC).  The total time of the research was 2.5 years.  The percentages of phosphorus, potassium, magnesium, and calcium suggest the use of the three substrates as organic fertilizer. A recommendation resulting from this research is to evaluate the sludge quality by mixing it with other substrates such as fruit peels with high nitrogen content and the sludge from wastewater treatment systems.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.1
      Issue No: Vol. 36, No. 1 (2022)
  • Excess Mortality Data Analysis of COVID-19 Infections and Fatalities in

    • Authors: Theofilos Toulkeridis, Esteban Ortiz-Prado, Jamileth Chunga-Moran, Marco Heredia-R, Alexis Debut
      Pages: 1 - 12
      Abstract: The global COVID-19 pandemic has shocked the world. Since the virus gave rise to health problems and often ended in deaths, the count of the contagion and the deceased has been an open issue. Such statistics are vital for every nation and even every city or district and suburb as these numbers decide the level of intervention and the subsequent reduction of its given spread. Worldwide data show a mortality rate of around two percent prior to successful vaccination campaigns. However, Ecuador's statistical data indicate an abnormal amount of excess mortality, which is officially denied in each of the studied countries. These numbers have been projected on a monthly basis and exceed up to 300% of the official COVID-19 deaths. In particular, the average mortality rate in Ecuador, prior to and close to the pandemic, has been about 6083.4±234.6, while in the worst month during the sanitary crisis, deaths piled up to 21,000 people, and only 1180 were recognized as deceased by COVID-19. The reasons are widespread but based on an insufficient financed health sector, political incompetence, lack of leadership, and a long-lasting economic crisis. Therefore, premature endings of confinements or lockdowns have contributed to an accelerated contagion and seem to even counteract the vaccination phase, in middle 2021, shortly before excess mortality ceased completely.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.17
      Issue No: Vol. 36, No. 1 (2022)
  • Covid-19 Vaccine Distribution: Combining SEIR and Machine Learning

    • Authors: Víctor Edgardo López-Sandoval
      Pages: 1 - 19
      Abstract: The purpose of this study is to build an epidemic model with vaccination control for Covid-19 in El Salvador. A combination of epidemiological SEIR (Susceptible, Exposed, Infectious or Recovered) models and the estimation of parameters using machine learning and contact networks is proposed. The project consisted of three phases: a) Analysis: the critical or key factors or variables of the phenomenon under study were identified, the model to be used, as well as its parameters and components, were defined, designed, and constructed b) Simulation: simulation made it possible to modify variables, implement alternatives, and modify the model itself without affecting the real system, which is highly useful for decision-making and preparing results and recommendations. The simulations were carried out using population data from El Salvador. c) Optimization: different scenarios were evaluated in which vaccination control measures and social distancing measures were applied, in order to identify the optimal strategy. As a result of this study, the best strategy for controlling the disease was identified: a combination of vaccinating the vulnerable population and maintaining social distancing measures provided the best results in terms of reducing the impact of infection and minimizing treatment costs. Finally, recommendations are made to government health authorities for distribution and application of the treatment.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.12
      Issue No: Vol. 36, No. 1 (2022)
  • Nitrates Evaluation in the National Térraba-Sierpe Wetland

    • Authors: Laura Hernández-Alpízar, Jesús Mora-Molina
      Pages: 1 - 11
      Abstract: This research aimed to describe, spatially and temporally, the concentrations of nitrates in correlation with anthropogenic activities surrounding the Sierpe River that crosses the National Térraba-Sierpe Wetland (HNTS). Although territorially protected by Costa Rican legislation, this wetland is surrounded by intense agricultural activity. In 2018, monthly monitoring of pH, nitrates, and dissolved oxygen was carried out in fourteen points of the river. A baseline around 5 mg NO3- / L was obtained in periods without agricultural activities and peaks up to 20 mg NO3- / L after fertilization activities. Correspondingly, a decrease in dissolved oxygen and pH was observed on days of high agricultural activity. In the months following fertilization, accelerated growth of aquatic plants and a general deterioration in mangrove reproduction were observed by collaborators of the HNTS management and surveillance program. Nevertheless, when high nitrates concentration in agricultural areas are observed,  their decline is also observed in the direction of the river's flow until it reaches its mouth.  This facts shows the still active function of the wetland and its importance in the processing of nitrates. To regulate activities not only in the territorial limit but also in the limits of the water system surrounding the HNTS is recommended to protect this ecosystem function.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.10
      Issue No: Vol. 36, No. 1 (2022)
  • Spectral reconstruction of kilovoltage photon beams using generalized
           simulated annealing

    • Authors: Jorge Homero Wilches-Visbal, Danny Giancarlo Apaza-Veliz, Patrícia Nicolucci
      Pages: 1 - 14
      Abstract: To unfold the energy spectrum of two kilovoltage (kV) X-ray beams from transmission curves through a mathematical methodology based on Laplace transform and the generalized simulated annealing algorithm. Energy spectra of photon beams and transmission data were associated by means of a mathematical expression derived from the analytical solution of Laplace transform. Transmission data was calculated by relating the air kerma of the attenuated beams, passing through aluminium plates of different thickness, to that of the non-attenuated beam. Generalized simulated annealing function, developed in an early work, was employed to find the parameters of the expression and so determine the spectra. Validation of the methodology was done by the comparison of the half-value layers obtained from transmission curves and the spectra. The mean square percentage error between transmission data and fitting curve of each spectrum defined from the parameters found was lower than 1% indicating a good adjustment. The same error was observed when the first half-value layer (HVL) from the transmission curves and those of each reconstructed spectrum were compared. Calculation time of parameters was 5 sec for 80 kV and 14 sec for 120 kV. In no case, non-realistic solution of energy spectra was obtained. These results were better than an early work where least-squares were used. The reconstruction methodology based on generalized simulated annealing employed in this manuscript can efficiently derive the spectra of two X-ray beams with comparable accuracy to previous work. A limitation is that validation was not done by comparing data with the equipment’s spectra.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.15
      Issue No: Vol. 36, No. 1 (2022)
  • Disaster risk management: competencies for a new hydro-environmental

    • Authors: Jeannette Arauz Muñoz, Cristian Moreira Segura, Claudia Charpentier Esquivel, Gustavo Barrantes Castillo
      Pages: 1 - 26
      Abstract: 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.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.8
      Issue No: Vol. 36, No. 1 (2022)
  • Bone level around dental implants adjacent to teeth and implants

    • Authors: John Jairo Gómez-Guzmán, Yohana Marcela Arias-Holguín, María Isabel Pérez, Felipe Augusto Restrepo-Restrepo, Carolina Rodríguez-Medina, Javier Enrique Botero
      Pages: 1 - 12
      Abstract: [Objective] This investigation seeks to determine the difference in bone level around implants adjacent to teeth and implants. [Methodology] This cross-sectional study included 17 patients with a total of 51 stable implants with a functional loading of at least 6 months. These implants were located next to natural teeth, other implants, or both. All implants and adjacent teeth were clinically examined, and periodontal and peri-implant parameters were recorded. A radiographic analysis was carried out to measure the bone level around implants in relation to the implant platform. Data were analyzed to detect differences between bone levels on the side of an implant next to a tooth compared to those on the side of an implant next to another implant. Statistical differences were considered significant when p≤0.05. [Results] The distance from the crestal bone on the coronal side of the implant platform to adjacent teeth or implants was approximately 1 mm. The bone level in zones adjacent to other implants was more apically located (2.9 ± 1.4 mm) than was the case for bone levels on sides adjacent to natural teeth (1.3 ± 0.07 mm) and the difference in these distances was statistically significant (p<0.05). Bivariate analysis showed that the bone level around implants was more likely to be coronal in relation to the implant platform on the side adjacent to a tooth than on the side adjacent to another implant (p=0.04). [Conclusions] The results indicate that the bone level of implants adjacent to natural teeth is maintained more coronal as compared to implants adjacent to other implants. This suggests a greater stability of implants when they are located near remaining natural teeth.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.13
      Issue No: Vol. 36, No. 1 (2022)
  • Social networks in wildlife protected areas of Costa Rica

    • Authors: Melissa Marín Cabrera
      Pages: 1 - 17
      Abstract: This article compares social participation networks in three wildlife protected areas in the Central Pacific of Costa Rica. These areas represent different management categories, which means different approaches to the use of natural resources. A mixed approach methodology was used to have a wider understanding of the socio-environmental processes in these areas. Analyses used included graph theory, social network analysis, and heat maps with attribute variables and global and positional network indicators. The elements of analysis included 40 civil society groups related to local development and environment conservation organized between 2009-2010 and 40 between 2019-2020. The analysis units were the interactions among the groups. Results show that the more centralized the social networks and the less power of local and multisectoral groups, the greater the dissociation of the topics related to sustainability of wildlife protected areas and the more vulnerable to structural and external changes. It is concluded that, from the structural dimension, participation networks are influenced by the management categories, since they condition the access to their ecosystem services. From the functional dimension, the capability of participation networks to transform ecosystem services into development opportunities is irrespective of the management categories, although it is related to other social aspects.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.6
      Issue No: Vol. 36, No. 1 (2022)
  • Nanotechnology diffusion strategy: interdisciplinary teaching to primary
           school teachers

    • Authors: Melissa Camacho-Elizondo, Diego Batista-Menezes, Rodrigo Mora-Bolaños, José Roberto Vega-Baudrit, Gabriela Montes de Oca-Vásquez
      Pages: 1 - 13
      Abstract: The objective of the research was to disseminate nanotechnology concepts, applications, and benefits among educators from different Costa Rican provinces to increase their acceptance and dissemination of the subject to elementary students. Teachers from different areas of the country were called to participate.  Five training workshops were held in Turrialba, Cahuita, Alajuela, Buenos Aires, and Nicoya covering fundamental nanotechnology concepts and applications, as well as the contributions offered from an educational point of view. The workshops were held in person two full days including talks, practical activities, and discussions. In addition, educational materials were prepared, such as a poster and an information brochure, and two educational videos on nanotechnology. A total of 98 teachers, 87% men and 13% women, from different provinces were trained. Workshop evaluations were positive in terms of the knowledge acquired with an average of 57.30%, compared to 5.10% before starting the training. This project contributed to strengthen teachers’ knowledge about nanotechnology and its applications. In addition, national and international nanotechnology research projects were made known. The above will help teachers disseminate new knowledge to the student population, thus becoming knowledge multipliers.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.3
      Issue No: Vol. 36, No. 1 (2022)
  • Mathematical Modeling in Statistical Activities: Key Episodes for Model

    • Authors: Àngels Aymerich, Lluís Albarracín
      Pages: 1 - 18
      Abstract: This work is intended to assist 15-year-old secondary school students to learn about statistics using mathematical modeling. Specifically, open statistical problems are presented in which real social phenomena are studied by students using large data sets that comply with the design principles of model-eliciting activities. The tasks assigned are aimed at presenting the concept of variability and its application to understanding the situations studied using a mathematical model. The study focuses on identifying key episodes in the activities in which progress is made in the construction of mathematical models, and the elements that promote them. To do so, a qualitative analysis is carried out based on records of the students’ group work in the classroom using Modeling Activity Diagrams. The results obtained show that decisions about the design of a problem, such as using large amounts of data, or the ambiguity of social concepts such as “fair taxation,” are essential for promoting the development of mathematical models. The conclusions of this investigation have implications for the design of statistical tasks, and also for identifying the role of mathematical modeling in the learning of statistical concepts.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.16
      Issue No: Vol. 36, No. 1 (2022)
  • Criteria guiding mathematics professors practice in engineering basic
           science courses

    • Authors: Walmer Garcés-Córdova, Vicenç Font-Moll
      Pages: 1 - 19
      Abstract: The study aims to infer the criteria that guide the practice of professors to explain mathematics, specifically derivatives, in a basic science course in the engineering program. This qualitative research of a multiple case study seeks to understand the teaching of differential calculus through the analysis of the practices of a group of seven professors, and the reflection on these practices when they implement their classes in engineering faculties of public and private universities in Lima, Peru. Each professor’s class was recorded. The criteria they follow to design and implement the classes were inferred, taking the didactic suitability criteria as a reference, which were also used to design the semi-structured interview questionnaire. Triangulation was done between what professors say and what they have been observed to do. It was noted that mathematics professors in engineering programs are completely conditioned by the subject syllabus when developing their derivative classes, as well as by the means and teaching resources and the availability of time for their differential calculus classes. Therefore, it is concluded that the priority criterion of the group of participating professors is meeting the curriculum in the time scheduled. On the other hand, they give more importance to adequately managing group interaction than teaching quality mathematics to be learned in a significant manner by students.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.5
      Issue No: Vol. 36, No. 1 (2022)
  • Specialized knowledge of polygons of math teachers in training

    • Authors: Elizabeth Advíncula-Clemente, Marisel Beteta-Salas, José León-Ríos, Isabel Torres-Céspedes, Miguel Montes
      Pages: 1 - 17
      Abstract: The paper is aimed to understand the specialized knowledge shown by a secondary education teacher in training when teaching polygons as part of her pre-professional practice on her senior year. This exploration was based on the Mathematics Teacher’s Specialized Knowledge (MTSK) model developed by a research group in the University of Huelva, Spain. The research methodology was qualitative. Based on an interpretive approach, a case study was used to identify, describe, and understand the student teacher’s geometric knowledge of polygons. Information was collected through non-participant observation, using recordings of three sessions with fifth graders of secondary education. In order to validate the analysis, we used external expert triangulation in the MTSK model. The results show the potential offered by the MTSK model as a tool to deepen the characterization and understanding of teachers’ knowledge, favoring the initial training of secondary education teachers by allowing them to reflect on the need to have a mathematical and didactic knowledge of the content to be taught. Results show how the knowledge of polygons is closely related to the knowledge of teaching mathematics linked to this subject, as well as to the knowledge of the characteristics of mathematics learning.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.7
      Issue No: Vol. 36, No. 1 (2022)
  • Guidelines for the analysis of mathematics textbooks lessons on the
           subject of proportionality

    • Authors: María José Castillo Céspedes, María Burgos Navarro, Juan Díaz Godino
      Pages: 1 - 21
      Abstract: The objective of this study is the construction of a guideline of indicators of didactic suitability related to the topic of proportionality, which can be used as a basis for the analysis and evaluation of textbook lessons, and as a resource for teachers’ reflection on effectively implemented instructional processes about proportionality. Since the study of proportional reasoning has become a relevant field of research in mathematics education, it is possible to identify specific suitability criteria for guiding the teaching and learning processes, applying the methodology of content analysis to a bibliographic review of key research in this area. Various aspects, components, and indicators of the notion of didactic suitability guide the selection and categorization of didactic-mathematical knowledge about proportionality in elementary and secondary education derived from research about such content. Finally, a Mathematics Textbook Lesson Analysis Guide adapted to the topic of proportionality was created. Since the textbook contains curricular material that largely determines what happens in the classroom and acts as a mediator in student learning, and ratios, proportions, and proportionality are studied in the curricula of elementary and secondary education, the Guide obtained can be a valuable resource for teachers. It is necessary to design and implement training actions with teachers that they are familiar with and can use competently, bearing in mind that there is always room for further improvement.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.14
      Issue No: Vol. 36, No. 1 (2022)
  • Knowledge of mathematics teachers in initial training regarding
           mathematical proofs: Logic-mathematical aspects in the evaluation of

    • Authors: Christian Alfaro-Carvajal, Pablo Flores-Martínez, Gabriela Valverde-Soto
      Pages: 1 - 25
      Abstract: The objective of this study is to characterize the knowledge of mathematics teachers in initial training (MTITs) at the Universidad Nacional (Costa Rica) on the logic-syntactic and mathematical aspects involved in proving, when evaluating mathematical arguments. The research is positioned in the interpretive paradigm and has a qualitative approach. It consists of two empirical phases: in the first, a questionnaire regarding logic-syntactic aspects was applied to 25 subjects, during the months of September and October 2018 and; in the second phase, a second questionnaire covering mathematical aspects was applied to 19 subjects, during the months of May and June 2019. For the analysis of the information, knowledge indicators were proposed.  Knowledge indicators are understood as phrases to determine evidence of knowledge in the responses of the subjects. It was appreciated that the vast majority of future mathematics teachers show knowledge to discriminate when a mathematical argument corresponds or not to a proof by virtue of the logic and syntactic aspects, and of mathematical elements associated with propositions with the structure of universal implication. In general, subjects displayed greater evidence of knowledge on the logic-syntactic aspects than on the mathematical aspects. Specifically, they evidenced that consideration of a particular case or the proof of the reciprocal proposition does not prove the result; likewise, subjects evidenced knowledge about the direct and indirect proof of the universal implication. In the case of the mathematical aspects considered as hypotheses, axioms, definitions and theorems, it was appreciated that subjects could have different levels of difficulties to understand a proof.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.9
      Issue No: Vol. 36, No. 1 (2022)
  • Implementation of the Mathematics curriculum in elementary school from the
           teacher’s perspective

    • Authors: Ronny Gamboa-Araya, Randall Hidalgo-Mora, Mario Castillo-Sánchez
      Pages: 1 - 33
      Abstract: The objective of this paper is to analyze, from the perspectives of elementary school teachers, the processes they carry out in their classrooms in terms of methodologies and evaluations used in the development of programs for the study of mathematics. A mixed approach was used in the study, which was based on a sequential design. Non-probabilistic sampling was used for convenience. In the first phase of the research, 117 elementary school teachers from schools in Costa Rica were surveyed. In the second phase, interviews were conducted with three teachers. A questionnaire was used to collect data, and semi-structured interviews were also carried out. The results obtained show that implementation of the Mathematics curriculum led to methodological changes and adjustments in the process of evaluation among the teaching staff, but also created problems. In general, the blackboard was the most used resource, but the use of additional tools has diversified. There is little use of technology and discussion of the history of mathematics as teaching resources. Knowledge of the curriculum is not adequate; priority is given to content, rather than to the development of skills. The teaching staff has difficulty in planning and developing problem-solving activities. Teachers should participate in continuous training processes in areas including mathematical knowledge, methodological and evaluation strategies, use of technology, and problem solving.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.11
      Issue No: Vol. 36, No. 1 (2022)
  • Persistent mathematical errors when entering initial teacher math
           training: the linearity case

    • Authors: Maitere Aguerrea, María Eugenia Solís, Jaime Huincahue
      Pages: 1 - 18
      Abstract: The objective of this research was to identify persistent errors of mathematical concepts and procedures, in particular, the incorrect application of the linearity concept, as well as implement learning situations to address errors of linearity by designing learning tasks in the context of modeling and the use of mathematical software. The study was applied to 42 students in the mathematics education program, during the 2019-2020 period. Research was conducted under a qualitative and longitudinal approach. Data collection began with a test upon entering the program and a second test after completing a semester of classes. Later on, collaborative workshops were implemented to address linearity errors, and a post-test was applied at the end. Upon entering the initial teacher math training, students showed a high percentage of errors, mistakenly applying linearity to roots, powers, logarithms, and trigonometry. After a semester of classes, these errors persisted. After the workshops, none of the participants made linearization errors in roots, powers and trigonometry, and only some continued applying linearity to logarithms. It was concluded that at the beginning of the program, students were still making errors in concepts and procedures that should have been overcome in school, and many of these errors are highly persistent. Using software in learning situations related to modeling would help students remedy those errors.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.4
      Issue No: Vol. 36, No. 1 (2022)
  • Teacher Reflection on a Teaching-Learning Situation Regarding the Concept
           of Relation in Secondary Education

    • Authors: Miguel Picado-Alfaro, José Romilio Loría-Fernández, Jonathan Espinoza-González
      Pages: 1 - 25
      Abstract: This study is part of the research in didactics of mathematics on 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.
      PubDate: 2022-01-31
      DOI: 10.15359/ru.36-1.2
      Issue No: Vol. 36, No. 1 (2022)
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Heriot-Watt University
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