[Recibido en octubre de 2011, aceptado en marzo de 2012] En este trabajo se discute el rol de la comunicación en el aula de ciencias y se delimita una forma de análisis relacionada con circuitos de interacción discursiva. Se comparan tres tipos de circuitos para clases de ciencias experimentales: exposición abierta, diálogo guiado e indagación dialógica problematizadora. Los datos resumen los registros de un grupo de investigaciones interpretativas desarrolladas por el equipo en los últimos diez años, las cuales analizan el diálogo asociado a temas de ciencias y ciclos de actividad. Se presenta la escala de análisis resultante y los tipos de secuencia de intervenciones de docentes y alumnos. Desde las mismas se modelizan circuitos de comunicación que van desde la clase tradicional a una constructivista.Se concluye respecto a la necesidad de incluir la problemática de la comunicación en el aula a lo largo de la práctica educativa y de los procesos de formación docente, haciéndola formar parte tanto del diseño, como del desarrollo y evaluación de la tarea docente.Palabras clave: comunicación en el aula; circuitos de interacción discursiva; ciencias. Communicative interaction in natural sciences lessons. A didactic analysis based on discursive circuitsThis work argues the role of communication in natural sciences classrooms and delimits a way of analysis in relation to interactive discursive circuits. Three types of circuits for experimental sciences lessons are compared: open exposition, guided dialog and problematic dialogic inquiry. The data summary the records of a group of interpretative research developed by the team in the last years ten years, which analyses the dialogue associated with science topics and cycles of activity. The resulting scale of analysis and types of intervention sequences held by teachers and students are presented. Based on them, communication circuits are modeled ranging from the traditional classroom to a constructivist one. It is concluded in relation to the need of including the problem of communication in the classroom throughout the educational practice and the processes of teacher training, making it part of the design, development and evaluation of the teaching task.Keywords: communication in the classroom; discursive interaction circuits; science. IntroducciónA lo largo de la práctica educativa un docente realiza actividades de diseño, desarrollo, evaluación y gestión, en el marco de una institución educativa. En todos estos itinerarios participa de intercambios discursivos expresados en forma oral, escrita o gestual, tanto con los alumnos, como con otros colegas y padres. Se generan así, distintos tipos de mensajes asociados al currículum, a las prácticas y al contexto de las instituciones. Rodríguez (2000) afirma que "educar es comunicar", destacando que todo el sistema educativo es básicamente un proceso comunicativo, relacionado a cómo establecer entre los participantes una interacción, mediante signos de significado compartido. Este proceso es de particular importancia ...

Since its introduction in the 1950s, tall fescue has spread throughout the Pampas region of Argentina to become naturalized in much of this region. Its annual forage mass productivity shows significant differences among sites. In this work, we hypothesized that, under dryland conditions, the annual forage mass productivity is related to the probability that the corresponding site is within the ecological niche of the species. To test this hypothesis, the spontaneous occurrence of tall fescue was surveyed in an area of 440 000 km2. The abundance of tall fescue was verified on roadsides of national and provincial roads, in systematic sampling points spaced every 50 km. Subsequently, the ecological niche of the species was estimated with the Maxent software, based on the environmental information available. Additionally, the bioclimatic variables with greatest influence in determining the ecological niche were identified. Based on the information of comparative yield trials of tall fescue cultivars, a correlation analysis between annual forage mass productivity and the likelihood of ecological niche was performed. We found that the realized ecological niche of tall fescue in the Pampas region covers an area of 237 000 km2 where the average minimum temperature of the coldest month is between 2·6 and 3·2°C and the rainfall in the driest quarter is 100 mm or higher. We also found that there were significant correlations between annual forage mass productivity and the probability of realized ecological niche. Therefore, in areas with low probability of realized ecological niche, other forage species could be a better option than tall fescue to obtain a high and stable annual forage mass productivity.

We present the results of the optical follow-up conducted by the TOROS collaboration of the first gravitational-wave event GW150914. We conducted unfiltered CCD observations (0.35 − 1µm) with the 1.5-m telescope at Bosque Alegre starting ∼ 2.5 days after the alarm. Given our limited field of view (∼ 100 ), we targeted 14 nearby galaxies that were observable from the site and were located within the area of higher localization probability.We analyzed the observations using two independent implementations of difference-imaging algorithms, followed by a Random-Forest-based algorithm to discriminate between real and bogus transients. We did not find any bona fide transient event in the surveyed area down to a 5σ limiting magnitude of r = 21.7 mag (AB). Our result is consistent with the LIGO detection of a binary black hole merger, for which no electromagnetic counterparts are expected, and with the expected rates of other astrophysical transients.

In spite of the scientific and technological development and a worldwide increment in the number of university students, it is evident a decrease in the number of students of physics in this level. This work brings out some features of the university education, particularly the teaching of the firsts courses. At the same time it is stated that a poor didactic knowledge, a rutinary teaching, that is not participative from the part of the teachers can be linked to a growing loss of interest from the part of the students. Finally the authors give some trends to make a deep study of this problem.