Un acercamiento al estudio del impacto de una secuencia de enseñanza-aprendizaje para mejorar la definición de tecnología

La ponencia se enmarca en el Proyecto Iberoamericano sobre la Naturaleza de la Ciencia y la Tecnología que busca mejorar en estudiantes la comprensión sobre la Naturaleza de la Ciencia y Tecnología (NdCyT), a partir del desarrollo de secuencias de enseñanza-aprendizaje (SEA) como lo es, en este caso, Tecnología: mucho más que aparatos. Ésta pretende hacer evolucionar creencias reduccionistas de estudiantes de nivel medio de Neuquén-Argentina respecto a la definición de Tecnología, involucrándolos en la resolución de una situación problemática como lo es el diseño de un baño en un campamento. Esperando culmine el procesamiento de resultados del pre y post test estandarizado aplicado para valorar el impacto pormenorizado sobre las mismas, adelantamos un somero análisis orientativo de sus respuestas a la actividad de reflexión metacognitiva

Wet and dry African dust episodes over eastern Spain

The impact of the African dust on levels of atmospheric suspended particulate matter (SPM) and on wet deposition was evaluated in eastern Iberia for the period 1996-2002. An effort was made to compile both the SPM and wet episodes. To this end, the time series of levels of TSP and PM10 in Levantine air quality monitoring stations were evaluated and complemented with the computation of back trajectories, satellite images, and meteorological analysis. Wet deposition frequency was obtained from weekly collected precipitation data at a rural background station in which the African chemical signature was identified (mainly pH and Ca2+ concentrations). A number of African dust episodes (112) were identified (16 episodes per year). In 93 out of the 112 (13 episodes per year) the African dust influence caused high SPM levels. In 49 out of 112 (7 episodes per year), wet deposition was detected, and the chemistry was influenced by dust. There is a clear seasonal trend with higher frequency of dust outbreaks in May-August, with second modes in March and October. Wet events followed a different pattern, with a marked maximum in May. Except for one event, December was devoid of African air mass intrusions. On the basis of seasonal meteorological patterns affecting the Iberian Peninsula, an interpretation of the meteorological scenarios causing African dust transport over Iberia was carried out. Four scenarios were identified with a clear seasonal trend. The impact of the different dust outbreak scenarios on the levels of PM10 recorded at a rural site (Monagrega, Teruel, Spain) in the period 1996-2002 was also evaluated

Variation of soluble and insoluble calcium in red rains related to dust sources and transport patterns from North Africa to northeastern Spain

We use the chemical composition of African dust delivered by red rains at a rural site in northeastern Spain (Montseny, 41460 N, 2210 E) to describe its relationship with the possible provenance areas and the processes occurring during transport. To this end, we obtained the red rain insoluble composition for the major elements (Al, Fe, Ca, Mg, K, P, Ti, and Na) in 30 filters, the 210Pb concentration in 23 filters, and the soluble cation concentrations (Na, K, Ca, and Mg) in 28 coincident red rain samples. These samples comprised most major events occurring at the site from 1983 to 2002. On the basis of back trajectories and satellite images, a distinction has been made between an eastern and western air mass flux with respect to 0 Greenwich for the analyzed samples. Principal component and ANOVA analyses between the two provenance groups have shown striking differences in the insoluble phase, with eastern samples being significantly richer in insoluble Ca, Mg, and Sr compared to western samples. Conversely, western samples had significantly higher concentrations of insoluble Al, Fe, K, V, and 210Pb than eastern samples. Therefore, in the insoluble phase, the ratios of various elements to Ca were significantly higher in western provenances. However, these differences disappeared when considering bulk Ca ratios (bulk Ca = insoluble + soluble Ca). Neither of the ratios Fe/Al and Ti/Fe showed significant differences. This lack of differences is interpreted in view of a similar carbonated lithology broadly underlying both areas. The difference in insoluble Ca with respect to total Ca between provenances (Cainsoluble/Catotal = 0.10 and 0.70 for western and eastern trajectories, respectively) is interpreted as a difference in calcite dissolution during transport. Evidence from 210Pb data and from the length of the back trajectories indicates that western trajectories covered a longer distance than the eastern ones; their higher soluble Ca could be due to (1) higher calcite dissolution due to longer contact with wet fronts from the Atlantic and (2) particle segregation during transport, with finer (carbonate) particles more prone to dissolution due to a higher surface to volume ratio

Nitrogen deposition in Spain : modeled patterns and threatened habitats within the Natura 2000 network

The Mediterranean Basin presents an extraordinary biological richness but very little information is available on the threat that air pollution, and in particular reactive nitrogen (N), can pose to biodiversity and ecosystem functioning. This study represents the first approach to assess the risk of N enrichment effects on Spanish ecosystems. The suitability of EMEP and CHIMERE air quality model systems as tools to identify those areas where effects of atmospheric N deposition could be occurring was tested. For this analysis, wet deposition of NO₃− and NH₄+ estimated with EMEP and CHIMERE model systems were compared with measured data for the period 2005-2008 obtained from different monitoring networks in Spain. Wet N deposition was acceptably predicted by both models, showing better results for oxidized than for reduced nitrogen, particularly when using CHIMERE. Both models estimated higher wet deposition values in northern and northeastern Spain, and decreasing along a NE-SW axis. Total (wet + dry) nitrogen deposition in 2008 reached maxima values of 19.4 and 23.0 kg N ha¯¹ year¯¹ using EMEP and CHIMERE models respectively. Total N deposition was used to estimate the exceedance of N empirical critical loads in the Natura 2000 network. Grassland habitats proved to be the most threatened group, particularly in the northern alpine area, pointing out that biodiversity conservation in these protected areas could be endangered by N deposition. Other valuable mountain ecosystems can be also threatened, indicating the need to extend atmospheric deposition monitoring networks to higher altitudes in Spain

Biological factors affecting larval growth in the nudibranch mollusc Hermissenda crassicornis (Eschscholtz, 1831)

The nudibranch mollusc Hermissenda crassicornis is used as a biomedical model for studying learning and memory. It is an eurytrophic benthic species with long-term, planktotrophic larvae, and it has been cultured in our laboratory for several years. This paper reports the effects of some dietary factors on H. crassicornis larvae that were investigated in order to establish the conditions 21 for optimal larval growth. Of the several treatments tested, densities of 1–4 larvae ml , a diet of Isochrysis galbana Parke and Rhodomonas salina (Wislouch) Butcher at a 1:1 mixture, and an 3 21 algal density of 10–25 3 10 cells ml yielded the largest, healthiest larvae, that underwent metamorphosis. Both diet quantity and quality, as well as larval density, had an effect on larval growth and metamorphosis of Hermissenda crassicornis in the laboratory. 1997 Elsevier Science B.V.Peer reviewe

Un acercamiento al estudio del impacto de una secuencia de enseñanza-aprendizaje para mejorar la definición de tecnología

La ponencia se enmarca en el Proyecto Iberoamericano sobre la Naturaleza de la Ciencia y la Tecnología que busca mejorar en estudiantes la comprensión sobre la Naturaleza de la Ciencia y Tecnología (NdCyT), a partir del desarrollo de secuencias de enseñanza-aprendizaje (SEA) como lo es, en este caso, Tecnología: mucho más que aparatos. Ésta pretende hacer evolucionar creencias reduccionistas de estudiantes de nivel medio de Neuquén-Argentina respecto a la definición de Tecnología, involucrándolos en la resolución de una situación problemática como lo es el diseño de un baño en un campamento. Esperando culmine el procesamiento de resultados del pre y post test estandarizado aplicado para valorar el impacto pormenorizado sobre las mismas, adelantamos un somero análisis orientativo de sus respuestas a la actividad de reflexión metacognitiva