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
Gomez-Paloma, F., Rio, L. & D'Anna, C. (2014). Physical self-efficacy in women's artistic gymnastic between recreational and competitive level. J. Hum. Sport Exerc, 9(Proc1), pp.S341-S347. In Bandura's theory (1997, 2001), self-efficacy is the cognitive mechanism that mediates information on personal capacities to successfully execute necessary courses of action in a specific domain. It is theorized that self-efficacy belief influences motivation, affect and behaviour. Self-efficacy regarding motor activities has been widely investigated (Feltz, 1992) and represents a frame of reference to explain links between cognitive processes and physical performance (Colella & Morano, 2008). The purpose of the study was to verify the difference in physical self-efficacy (perceived) between gymnasts practicing sports at recreational level and gymnasts, however, which train at a competitive level. The Perceived Physical Ability Scale for Children by Colella (2008) was presented to a sample of 58 gymnasts, 29 practicing sports at recreational level and 29 practicing sports at competitive level in random selection, ranging in age from 8 to 10 years old. The items of the PPASC are: speed, ability, strength, rapidity, self-confidence and tiredness. They are structured in response scales having a 1-to 4-point format. Observing the results of the descriptive statistics in the whole sample it is obvious how the perceived physical abilities are very high in all items. The artistic gymnastic is a sport in which these aspects of physical abilities are trained specifically. The children say that they run fast (77 %), they are able to do difficult exercises (77%), their muscles are strong (68%) and move rapidly (71%). Slightly lower values are those related to self-confidence, the 48% say that they feel sure when they move but the 32% say that they feel somewhat insure when they move, and the value of energy, 50% say I don't feel tired when I move, but the 25% say that they feel tired. The difference between the values of the two levels of gymnastic report in the competitive groups is higher in physical self-efficacy in all items than in the recreational group. These data could suggest that the quantity of the trainings and, at the same time, the improvement of the quality of the performance increases the Perceived Physical Ability. The results of the test is particularly high and considering it globally, confirms that, in any case, the physical activities, even if only practiced as recreational activity, produces positive effects on the Perceived Physical Ability.
Savino, L., Rio, L., & Gomez, F. (2015). The adapted physical activity as a valuable tool to overcome social prejudice to the disabled persons. J. Hum. Sport Exerc., 9(Proc1), pp.S418-S424. The Adapted Physical Activity, in modern times, is defined as the program with an educative target so it promotes the autonomous recovery of the person through direct experience of physicality (Cottini, 2008). The ICF (WHO, 2001) is a guide achieving this objective because it defines disability as the product of the relationship between the health of the person and the context in which he lives. The context creates disability because it doesn't have the appropriate tools to allow the free expression of the person for the different life contexts (Cottini, 2008). Finally the "conquest" consists in the implementation of Adapted Physical Activity. This activity is expressed in the manipulation of the physical context according to the various needs of the person to improve all their dimensions. The TMA test is the methodology used to evaluate the functionality of Adapted Physical Activity to empower the global person's self-esteem. This instrument has favored a primary monitoring to understand the initial condition of the four disabled, involved in the research work, and the whole class group. The results obtained in this first phase were classified as negative according to the American standardized sample. The test had determined how the global self-esteem of the disabled person was influenced by his conditions of marginalization determined by the prejudice that limited action. The A.P.A., during the hours of physical education, has facilitated the achievement of positive results compared to those of departure. These results represent a pratical demonstration of how prejudice is an abstract entity resulting from the lack of people knowledge. In any case the activity has placed all subjects on the same plane to achive a performance, a common target. The person's improvement is the starting point in the understanding of this work.
Resumen. En este artículo se esbozan los fundamentos teóricos que sustentan la utilización de la vista gráfica 3D de GeoGebra como herramienta para la enseñanza y el aprendizaje del Cálculo Diferencial e Integral. También se comparten algunas ideas, a modo de ejemplo, de construcciones que pueden realizarse para ayudar a comprender algunos conceptos que suelen resultar difíciles para los alumnos, debido a la gran dificultad de representarlos gráficamente utilizando sólo lápiz y papel, obligando al estudiante a limitarse a su manipulación algebraica. Los ejemplos abordados se relacionan con los temas: sólidos de revolución, extremos relativos en funciones de dos variables y cálculo de límites en funciones de dos variables.Palabras clave: Cálculo diferencial, Cálculo integral, Geometría Dinámica, GeoGebra, Visualización en 3D. Abstract.This article develops a theoretical framework to support the use of GeoGebra 3D view as a tool for teaching and learning Calculus. It also shares a few ideas, as examples, of constructions that can be done to help students to understand some concepts that can be hard due to the impossibility of represent them using only pencil and paper. This situation forces students to just manipulate algebraically the mathematic objects. The presented examples are related to the following topics: Solid of revolution, relative maximum and minimum (for two variables functions) and limits of two variables functions.
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