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Although student covariation reasoning has been explored in depth to improve understanding of the correspondence between variables, research has focused on studying existing reasoning about variables in Cartesian representations. The working method had a qualitative approach, with a descriptive exploratory scope, the spontaneous representations that the participants evidenced under the level of covariational reasoning of the variables present in three contextualized situations were explored, posed to a population of third-grade middle school students. The students argued with concrete and abstract drawings the general behavior of the variables. At low levels of reasoning they used pictorial representations, at higher levels they used graphical diagrams and tables. The exploratory study shows a relationship between the type of spontaneous representations and the student's level of covariational reasoning, as well as the rigor of the description of the problem.

The present educational intervention study focused on addressing some areas of improvement in the teaching and learning of trigonometric ratios in high school students. A diagnostic evaluation was performed that revealed an instrumental understanding of trigonometric concepts by the students. Subsequently, a didactic sequence was implemented that incorporated practical applications of trigonometric ratios in the context of displacement vectors. The results of the study indicated significant improvements in students' understanding after the intervention, marking a shift toward relational understanding. This proposal is presented as an effective strategy and suggests promising ways to improve pedagogy in this field.

This research reports the implementation of an evaluation instrument of the slope concept in high school students. The design of this study was based on four dimensions: Skills, Properties, Uses and Representations (SPUR model; Thompson & Kaur, 2011) and on three conceptualizations: constant ratio, behavior indicator and trigonometric conception. This work adopts a qualitative approach to analyze the students' productions and a quantitative approach when obtaining the percentages of the student's responses. The general objective of the work is to evaluate the effect produced by a group of tasks designed with the SPUR model on the slope concept in high school students. The results show that students have traditional conceptualizations of the slope as a constant ratio and trigonometric conception. However, these conceptualizations emphasize more procedural aspects than conceptual ones. This finding could partially explain why students can solve certain tasks of procedural nature but not conceptual tasks that usually require a multifaceted view of the slope.

This report delineates the outcomes of an intervention conducted with in-service high school educators, focusing on elucidating three distinct scenarios within geometric and arithmetic domains: the infinitely large, infinitely numerous, and infinitesimally close. Grounded in the theoretical framework of conceptual change, it is posited that when an individual exhibits entrenched conceptions, it signifies a misclassification of the pertinent concept, necessitating a categorical shift to effectuate a transformation in their cognitive schema, particularly concerning the notion of infinity. Thus, the principal objective of this investigation was to ameliorate the entrenched conceptions held by educators pertaining to infinity through a workshop-based intervention. Preceding the workshop, educators predominantly exhibited conceptions aligned with natural and potential infinities. However, after the workshop, a discernible transition was observed, with educators engendering an actual conception of infinity or an omega-epsilon position, exemplified by their acceptance of equivalences such as 0.999…=1 and the parity in the cardinality of sets comprising natural numbers, even numbers, and perfect squares. Nonetheless, notwithstanding this progress, confident educators evinced resistance to embracing the concept of actual infinity, particularly in instances such as the hypothetical scenario depicted in Hilbert's Grand Hotel. Consequently, drawing upon the framework of conceptual change theory, it can be postulated that a complete categorical shift was not universally realized among educators due to their reluctance to revise entrenched beliefs concerning natural or potential infinity.

The present research focuses on analyzing how fourth-grade elementary school students (ages 9 to 10) solve and interpret the result of non-routine problems, precisely division measurement and division-partition with remainder. The methodology is qualitative, with a descriptive and interpretative approach. The information was collected using a questionnaire consisting of three problems (two of quotitive division and one of partitive division) and a clinical interview. The results showed the importance of using the division, multiplication, and addition algorithms to give a realistic answer to the problems. In the same way, it was possible to demonstrate the graphic strategy combined with counting to give a realistic answer to the problem. However, students were found to use division correctly but without an interpretation of the remainder or quotient. Likewise, they struggled to choose the correct procedure to solve the problem. These data suggest including realistic problems in mathematics classrooms to make sense of mathematical concepts in real life or the student's context. Likewise, this study provides implications on the mathematical problems that the teacher proposes in the classroom, where not only the division algorithm should be taught mechanically, nor focus on posing routine problems that lead the student to use a single heuristic resolution strategy. Essentially, the teacher is required to include real-world problems, where the student can awaken creativity to represent in different ways the understanding of a problem and, therefore, different strategies to solve it. In addition, that the student has the ability to check the result of the problem, with the conditions, situations or circumstances imposed by reality or everyday life. [This is a reprint of an article originally published in "Mathematics Teaching Research Journal" v14 n5 p159-180 Win 2022.]

México cuenta con zonas con alto potencial para la producción de hierbas finas, su creciente demanda las ha convertido en productos con un nicho de mercado rentable y en expansión, además representan una alternativa económica a los cultivos tradicionales. El presente trabajo integra una revisión que destaca la importancia de las hierbas aromáticas y medicinales, así como los usos más comunes por la población que las consume para tratar malestares de diversa índole. También contiene las cifras de rendimiento y valor de la producción de las principales hierbas aromáticas que se producen a nivel nacional. Se destaca que la mayoría de las especies aromáticas y medicinales se producen para el mercado de exportación, los migrantes mexicanos y asiáticos son los principales consumidores en Estados Unidos y Canadá. Conforme a los indicadores del SIAP, la recolección y la producción de hierbas aromáticas y medicinales representan una actividad de alta rentabilidad para recolectores, productores y transformadores.

El presente artículo presenta un bosquejo general de los sustratos de uso hortícola, las ventajas, los factores a considerar en su elección y las propiedades físicas, químicas y biológicas que se deben evaluar. Esto porque en la actualidad, los sustratos representan un componente importante en la agricultura moderna, específicamente en los sistemas semi-hidropónicos de especies hortícolas. Se concluye, que existe una gran diversidad de materiales que pueden utilizarse como sustratos agrícolas, pero existen criterios que deben considerarse para su elección como: requerimientos de las plantas, que se ajusten en lo posible a las características ideales de un sustrato, así como efecto en el medio ambiente.

La extracción nutrimental determina la cantidad de nutrimentos extraída por una planta, puede cuantificarse en una etapa fenológica determinada o a través del ciclo de cultivo. Es una forma para establecer cuánto fertilizante se debe aplicar al cultivo de chile mediante el cálculo de la cantidad de nutrimento requerido por la planta para expresar un rendimiento esperado, por lo tanto, la cantidad necesaria de nutrimento para producir una tonelada de producto fresco debe ser un dato conocido. Se revisó literatura científica actualizada acerca de la cantidad de nutrimentos que extrae el cultivo de chile por tonelada de frutos frescos cosechados al igual que las partes vegetales no destinadas para consumo (follaje, tallos, raíces), es decir, el requerimiento nutrimental específico de chile; asimismo, se revisó la distribución de los nutrimentos en los órganos de las plantas, cómo es influenciada por las diferencias en tecnología de producción, rendimiento y las condiciones del suelo. Se encontró que la extracción y requerimientos nutrimentales en chile variaron por cultivares, tipos de chiles (jalapeño, dulce y pimiento), órgano muestreado y por sistemas de producción. De acuerdo con los resultados encontrados en esta revisión, se puede asegurar que el requerimiento nutrimental específico del cultivo de chile que sirva de base para el cálculo de dosis de fertilización, es como se indica a continuación (en kg t-1): Nitrógeno (N), 2.4 - 4.0; Fósforo (P2O5), 0.4 - 1.0; Potasio (K2O), 3.4 - 5.29, Calcio (CaO): 0.55 - 1.80 y Magnesio (MgO), 0.28 - 0.49.

Los objetivos del presente artículo son presentar la situación actual de la horticultura protegida en Nayarit, México y visualizar su probable crecimiento y desarrollo con la implementación de un clúster agroindustrial en el sur. Se describe, de manera general, la situación actual de la horticultura en México, se indican algunos factores agronómicos que favorecen este sistema de producción en el estado y se presenta la situación actual del establecimiento de invernaderos como parte del Clúster Agroindustrial del Sur de Nayarit; asimismo, se visualizan posibles beneficios socioeconómicos con su implementación. Se concluyó que la horticultura protegida en Nayarit está en rápido crecimiento y desarrollo. Se espera que con la puesta en marcha del Clúster Agroindustrial se impulse la economía y el sector agrícola de la entidad; se prevé también un incremento en la exportación de hortalizas y que aumenten las opciones de empleo de ingenieros agrónomos.

Durante el crecimiento y desarro- llo de las flores, la nutrición fosforada es un factor que puede influir en la vida en flore- ro. El objetivo de este trabajo fue evaluar el efecto de cinco niveles de fósforo (P): 0, 0.5, 1.0, 1.5 y 2.0 me·L-1 de P aplicados en precosecha, mediante un sistema hidropóni- co abierto, en el comportamiento fisiológico postcosecha de tallos florales de rosa (Rosa hybrida L.) ‘Classy’ y ‘Vega’. Las variables evaluadas durante la vida de florero de los tallos florales fueron: transpiración foliar y floral, potencial de turgencia foliar y de pétalos. Además, se evaluó la concentración de antocianinas en pétalos al momento de la cosecha. Las aplicaciones de P en precose- cha tuvieron efecto significativo únicamente en la transpiración foliar; sin embargo, se demostró que la mayor vida en florero (15.8 días) de ‘Classy’ en comparación con ‘Vega’ (11.7 días) estuvo directamente asociada con mayores potenciales de turgencia foliar y de pétalos, mayor tasa transpiratoria floral y menor tasa transpiratoria foliar en ‘Classy’.

The present research focuses on analyzing how fourth-grade elementary school students (ages 9 to 10) solve and interpret the result of non-routine problems, precisely division measurement and division-partition with remainder. The methodology is qualitative, with a descriptive and interpretative approach. The information was collected using a questionnaire consisting of three problems (two of quotitive division and one of partitive division) and a clinical interview. The results showed the importance of using the division, multiplication, and addition algorithms to give a realistic answer to the problems. In the same way, it was possible to demonstrate the graphic strategy combined with counting to give a realistic answer to the problem. However, students were found to use division correctly but without an interpretation of the remainder or quotient. Likewise, they struggled to choose the correct procedure to solve the problem. These data suggest including realistic problems in mathematics classrooms to make sense of mathematical concepts in real life or the student's context. Likewise, this study provides implications on the mathematical problems that the teacher proposes in the classroom, where not only the division algorithm should be taught mechanically, nor focus on posing routine problems that lead the student to use a single heuristic resolution strategy. Essentially, the teacher is required to include real-world problems, where the student can awaken creativity to represent in different ways the understanding of a problem and, therefore, different strategies to solve it. In addition, that the student has the ability to check the result of the problem, with the conditions, situations or circumstances imposed by reality or everyday life.

Copyright of Revista Venezolana de Gerencia (RVG) is the property of Revista de Filosofia-Universidad del Zulia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study employing a qualitative approach, we explore and compare the mathematical reasoning of active primary school teachers and individuals with limited education when tackling problems involving false proportionality and lack of authenticity. The research is justified by the importance of understanding how these issues are addressed in various educational groups and how teaching strategies in this area can be enhanced. An individual questionnaire containing five problems was administered to five participants in each group. The results indicate that teachers tend to more frequently succumb to the illusion of linearity, incorrectly applying linear relationships to non-proportional problems compared to individuals with lower educational attainment. This suggests a greater influence of algorithmic approaches and clauses of the didactic contract on their mathematical reasoning. This tendency could be attributed to a greater exposure to algorithmic approaches during the formative stages, as well as certain clauses in the experimental contract. Conversely, individuals with limited education approached problems with greater flexibility, linking their responses to everyday experiences. The study concludes that it is imperative to implement educational strategies aimed at overcoming limitations such as the illusion of linearity and fostering meaningful problem-solving skills from the early stages. It is recommended to developteacher training programs that promote a more contextualized and flexible approach to mathematics teaching, as well as the include contextualized and meaningful problems in the school curriculum. [ABSTRACT FROM AUTHOR]

Copyright of Ecosistemas y Recursos Agropecuarios is the property of Universidad Juarez Autonoma de Tabasco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ecosistemas y Recursos Agropecuarios is the property of Universidad Juarez Autonoma de Tabasco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Natural Protected Areas (NPA) network is one of Mexico's main biodiversity conservation strategies. However, comparisons between the biodiversity observed inside and around this conservation instrument have rarely been performed in the country, not even for groups of fauna such as medium and large mammals (weight > 0.5 kg). Aspects of diversity and abundance of medium and large mammals were determined inside the Cañon del Usumacinta Flora and Fauna Protection Area (inside NPA) and in unprotected areas surrounding the NPA (outside NPA) through 72 camera trap stations (41 stations inside and 31 outside NPA). We obtained 1333 records of medium and large mammals of 23 species inside the NPA, while 663 records of 22 species were obtained outside the NPA. The expected species richness, diversity, and species composition by camera station were similar between interior NPA and exterior NPA. Likewise, the shape of the rank-abundance curves was similar inside and outside the NPA but not in the species order. Also, we found differences among the mean weight of the species registered by the camera station with larger species captured in the interior of the NPA. Our results showed that although the diversity of medium- and large-sized mammals is similar between the interior and exterior of the NPA, the conservation actions carried out in the interior of the NPA allow the larger mammal species (generally exposed to subsistence hunters) to be more detectable within the NPA than outside. It is necessary to determine which programs helped reduce the pressure on the largest mammals in the NPA, to maintain their operation and extend it to other NPAs of the region. [ABSTRACT FROM AUTHOR]

Introduction The Meckel’s diverticulum (MD) is the most common congenital anomaly of the gastrointestinal tract present in approximately 1–4% of the population; the MD duplication is exceedingly rare with only a few reports of it. Here we present the firs case of a strangulated Littre’s hernia with MD duplication. Presentation of case A 30-year-old male presented to the emergency room with clinical signs of small bowel obstruction, at physical examination, a right incarcerated inguinal hernia with erythema was found. We did a laparotomy, and two MD were found, one in the sac with ischemia, and the other 90 cm from the Bahuińs valve. A diverticulectomy of the ischemic diverticulum was done, and the other MD was left in place; the inguinal region was repaired with a Lichtenstein technique. Discussion The complications of the MD are 3–4 times more frequent in men, been an intestinal obstruction, hemorrhage, diverticulitis, ulceration, and perforation. A Littrés hernia is when the MD is found in the sac; this is seen in the inguinal region in 50% of the cases. The management of a Littre’s hernia is the resection of the MD; it could be done by an intestinal resection or by a diverticulectomy accordingly to the Park criteria. Conclusion As to our knowledge, this is the first case of an incarcerated Littre’s hernia with duplication of a Meckel’s diverticulum. [ABSTRACT FROM AUTHOR]

Copyright of Acta Universitaria is the property of Universidad de Guanajuato/Acta Universitaria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article traces the introduction, in the early 20th century, of food recipes targeting childhood nutritional needs as evidenced in Mexican cookbooks from the period (1911 to 1950). The author considers the ideological and social currents behind the development of childhood--which he defines to include children and infants--as a distinct social category with unique dietary needs. He also considers how cooking recipes as historical sources shed light on Mexican family and health in the early 20th century.