Summary: The factors involved on the silicification process in Cyperaceae are scarcely known. In this study we analyse the effect of maturation stage and silica availability on the production of amorphous silica biomineralizations in culms of Schoenoplectus californicus. Young and senescent culms were collected from ponds with different silica availability. Two complementary methodologies (calcination and staining techniques), light and scanning electron microscopy and EDS were applied for amorphous silica analyses in plants. Quantitative data were analysed by Kruskal-Wallis and a two-way ANOVA tests. There were no significant differences between silica content of culms collected in ponds with different silica availability. Instead, silica content in senescent culms was higher than in young culms (F=91.43, P<0.01). Young culms only produce cone-shaped amorphous silica bodies, located in epidermal cells overlying sclerenchyma. Senescent culms produce a higher diversity of silicified cells, such as epidermal, stellate (aerenchyma) and parenchymatic cells. Silicification process in S. californicus is clearly affected by age and may act as a mechanism of structural resistance improvement. Some cells became silicified very early in the development and others may be silicified at a later stage depending on wall characteristics or rate of transpiration.Key words: Sedge, silicophytoliths, senescence, aerenchyma, culms, ponds, SE Buenos Aires province.Resumen: Biomineralizaciones de sílice amorfo en Schoenoplectus californicus (Cyperaceae): su relación con el estado de maduración y la disponibilidad de sílice. Los factores involucrados en el proceso de silicificación en Cyperaceae son poco conocidos. En este estudio se analiza el efecto del estado de maduración y la disponibilidad de sílice en la producción de biomineralizaciones de sílice amorfo en tallos de Schoenoplectus californicus. Tallos jóvenes y senescentes fueron recolectados de lagunas con diferente disponibilidad de sílice. Dos técnicas complementarias (calcinación y tinción), microscopía óptica y electrónica y EDAX fueron aplicados para el análisis en las plantas. Los datos cuantitativos fueron analizados por tests de Kruskal-Wallis y ANOVA de dos vías. No hubo diferencias significativas entre el contenido de sílice en los tallos recolectados en lagunas con diferente disponibilidad de sílice. En cambio, el contenido en tallos senescentes fue mayor que en los jóvenes (F=91,43; P<0,01). Los tallos jóvenes solo producen cuerpos silíceos cónicos, localizados en células epidérmicas asociadas al esclerénquima. En los tallos senescentes se silicifican una mayor diversidad de células, como las epidérmicas, del aerénquima y esclerénquima. El proceso de silicificación en S. californicus está claramente afectado por la edad y mejoraría la resistencia estructural. Algunas células se silicifican tempranamente, mientras que en otras depende de las características de la pared celular y/o de la tasa de transpiración.Palabras clave: Junco, silicofitolitos, senescencia, aerénquima, tallos, lagunas, sudeste bonaerense.

D'Anna, C., Rio, L., & Paloma, F. (2015). Competitive sport and self-concept in adolescent. J. Hum. Sport Exerc., 9(Proc1), pp.S425-S429. Self-esteem is the degree to which an individual values himself or herself globally. Several studies have shown that the self-esteem level is a key indicator of positive mental health and well-being. The belief that physical activity and sport are often associated with the best development of self-esteem in adolescent is a commonly held view. However in literature there aren't many studies that investigate the self-esteem level in young athletes that practice competitive sport activities. The aim of this study is to assess the self-esteem level comparing athletes who practice individual sport with athletes who play team sports. In last ten years it has become widely accepted that self-esteem is structured hierarchically and therefore on the top of all there is general self-esteem and secondly there are the various interrelated dimensions between them. The sample consisted of seventy-eight individuals, basketball athletes (M= 20, F= 14) and gymnasts (M=19, F=25). All the participants compiled the Multidimensional Self-Esteem Test (TMA, Erickson), a structural questionnaire on the specific domains (interpersonal relationship, competence, emotionality, school, family, body image). The results showed that both females and males who were physically involved in the practice of sports at competitive level (indifferently whether individual or team sport) have considerably highest level of self-esteem. This data confirms that individuals with the a higher self-esteem manage to apply themselves better in the high-level sports and, at same time, that the competition, for the all disciplines of sport, further strengthens self-esteem.

The use of hypermedia educational materials in education has gained relevance in recent years and is the object of numerous research activities. In the context of teaching and learning Mathematics, there are diverse works detailing their potential to improve both student learning and student attitude towards the subject. In this article, the results obtained through a case study carried out in a first-year course of Mathematics at a School of Engineering are shared, for which a hypermedia material was designed and then its impact in the classroom was analysed. To that end, a quanti- qualitative analysis framework was designed. An experience was carried out with two groups of students: one of these (n=101) used this material, and the other (n=111) served as control group. The students gave a positive overall assessment as regards to the experience carried out with the hypermedia material, but not to the extent expected. However, observations and the interviews carried out with the educators revealed that the hypermedia material positively contributed to several student learning aspects: it allowed using a mathematical software application as an exploratory tool and it promoted critical thinking among the students, who used the application to check their pen-and-paper work, using the semiotic representation conversions.

In this paper, we describe an inclusive, collaborative learning approach in which both able and less able students engaged together in a contest combining Photography, Mathematics and Technology, in our case GeoGebra. Following three cycles of the contest, we analysed a selection of entries and the related post-participation survey. Based on the analysis, we concluded that the combination of these approaches could help to engage students with mathematical content by relating art, their surrounding environment with mathematics. This approach enabled us to offer different ways of mathematics learning through providing contexts for exploration and students’ creation of their own contents. Results also showed that school teaching is sometimes insufficient to solve emerging problems and this challenged students to find new kinds of solutions supported by new tools and concepts. It also allowed students to think creatively by inviting them to work together to develop their own questions, problems, and facilitating learning by research.

En el presente trabajo se relata la experiencia de nuestro equipo docente en el marco de la contingencia provocada por la pandemia de COVID-19. Nuestra universidad decidió en este particular contexto ratificar su calendario académico y garantizar la continuidad pedagógica a través de la modalidad de enseñanza a distancia. Este requerimiento nos puso a los docentes de la casa a pensar y a actuar con gran celeridad, seleccionando las herramientas y metodologías que consideramos más adecuadas para garantizar el derecho a continuar estudiando a la mayoría de nuestros estudiantes. En este trabajo, queremos presentar las estrategias didácticas llevadas a cabo por nuestro equipo docente -el cual está a cargo de una comisión de la cátedra Matemática A, de la Facultad de Ingeniería de la Universidad Nacional de La Plata-, algunas de las dificultades que nos hemos encontrado en este camino y algunos resultados que nos permiten valorar positivamente la experiencia. PALABRAS CLAVE:  Educación virtual de emergencia, COVID-19, Enseñanza de la Matemática, TIC y Educación