Estrategias de aprendizaje utilizadas por estudiantes de educación media del ámbito científico en comunas vulnerables de la región de la Araucanía, Chile

La presente ponencia está basada en el proyecto de investigación FONDECYT Regular 1100378: “Hacia un aprendizaje de calidad en la Educación Científica. Estrategias didácticas para el desarrollo de capacidades y valores.” El objetivo general de esta investigación, es: “desarrollar en los alumnos de Segundo Ciclo de Educación Media de cuatro comunas vulnerables de la Región de la Araucanía, Chile, las capacidades y valores involucrados en un aprendizaje de calidad, a través de la práctica de adecuadas estrategias de aprendizaje por parte de los estudiantes y de adecuadas estrategias de enseñanza por parte de sus profesores de Biología.” Para esta ponencia, se ha seleccionado parte del objetivo especifico: “construir conocimiento, sobre el avance producido en la calidad del aprendizaje de los estudiantes, expresado en términos de conocimiento, selección y aplicación de estrategias cognitivas y afectivas de aprendizaje, como asimismo, sobre el avance producido en el proceso de mediación de los profesores, expresado en términos del conocimiento, selección y puesta en práctica de estrategias de enseñanza que faciliten el avance en la calidad del aprendizaje de sus alumnos.” La ponencia se centra en la presentación de resultados de una técnica de recolección de datos - en concreto ocho grupos focales aplicados a los estudiantes - se procede a su análisis y se discuten sus implicancias en el proceso educativo

Out-of-equilibrium relaxation of the Edwards-Wilkinson elastic line

We study the non-equilibrium relaxation of an elastic line described by the Edwards-Wilkinson equation. Although this model is the simplest representation of interface dynamics, we highlight that many (not though all) important aspects of the non-equilibrium relaxation of elastic manifolds are already present in such quadratic and clean systems. We analyze in detail the aging behaviour of several two-times averaged and fluctuating observables taking into account finite-size effects and the crossover to the stationary and equilibrium regimes. We start by investigating the structure factor and extracting from its decay a growing correlation length. We present the full two-times and size dependence of the interface roughness and we generalize the Family-Vicsek scaling form to non-equilibrium situations. We compute the incoherent cattering function and we compare it to the one measured in other glassy systems. We analyse the response functions, the violation of the fluctuation-dissipation theorem in the aging regime, and its crossover to the equilibrium relation in the stationary regime. Finally, we study the out-of-equilibrium fluctuations of the previously studied two-times functions and we characterize the scaling properties of their probability distribution functions. Our results allow us to obtain new insights into other glassy problems such as the aging behavior in colloidal glasses and vortex glasses.Comment: 33 pages, 16 fig

Cobre, zinc y cromo en agua, sedimento y biota en la laguna Chascomús (Argentina)

Contamination caused by heavy metals (copper, zinc and chromium) was studied in a Pampean lake and its biomagnification was considered. The samples were taken seasonally in different sites of the Chascomus lake during 1996 and 1997. The three elements were measured in water, sediments, fish muscle and viscerae. clam muscle, phytoplankton and zooplankton. The concentration was higher than the limits allowed for acuatic life by international and domestic legislation. Spatial and temporal differences were detected both in water and sediments. The average value of total copper observed in water was 1.78 mg/l. The average value of total zinc in water was 0.19 mg/l. A higher quantity of zinc than copper was accumulated in the sediments. Hexavalent chromium was of 0.12 mg/l in its average value. Accumulation was found in the viscerae and muscles of the ichthyofauna. In the benthic fauna, copper concentration in muscle decreases according to the species' swimming capabilities. In the limnetic fauna the concentration increases in higher trophic levels.Se analizó la contaminación por algunos metales pesados (cobre, zinc y cromo) en la laguna Chascomús y se consideró su biomagnificación. Los muestreos se realizaron estacionalmente en 1996 y 1997. Se midieron los elementos mencionados en agua, en sedimentos, en músculos y vísceras de peces, músculo de almejas, en fitoplancton y en zooplancton. Se encontraron altas concentraciones de los tres elementos analizados, superando el valor límite aconsejado para la vida acuática. Se comprobaron diferencias espaciales y temporales tanto en agua como en sedimentos. El valor promedio de cobre total observado en el agua fue 1,78 mg/l. el de zinc total en agua de 0.19 mg/l y el de cromo hexavalente de 0,12 mg/l. En el sedimento se determinó mayor concentración de zinc respecto a cobre. En la fauna íctica se encontró acumulación en vísceras y en músculo. En la fauna asociada a los sedimentos, cuanto más nadadora es la especie considerada, menor fue la concentración de cobre encontrada en músculo. En cuanto a la fauna relacionada a la zona limnética, la concentración aumentó a medida que avanzamos en el nivel trófico.Facultad de Ciencias Naturales y Muse

Nutrientes y clorofila-a durante el período de inundación 2001-2002 en la Laguna Chascomús (Argentina)

Total phosphorus, total nitrogen and chlorophyll-a concentrations were determined weekly in a pelagic zone in Chascomús Pond between April 2001 and September 2002. Two flood periods took part with 8 metres over sea level (IGM) during this time (June- January 2002 and April-June 2002), where in both of them two maximum peaks with about 9 meters were registered. As a consequence a diminution of the salinity to one third of the mean value of 1,57 g.l-1 was observed, because of the dilution promoted by rainwater which was higher in a 40% of the mean 600 mm of the latest five years. Nevertheless, this fact had not occurred with total phosphorus, mean 0,48 mg.l-1, referring to 0,48 mg.l-1 obtained in 1999-2000, while total nitrogen, mean 1,45 mg N.l-1, was nearly in the same order in relation to a previous value of 1,56 mg N.l-1 (1983-1984) and chlorophyll-a, mean 198,2 μg.l-1, showed a significant increment taking into account the concentration of 89,1 μg.l-1 determined during 1999-2002. These results indicate that because of flood events a supply of nutrients reaches the pond coming from wastes of the city (30000 inhabitants), as well as from the effluent of the treatment plant. Normally, the latter go to Girado stream and finally are received by Adela Pond in direction to Salado River, but the inversion of the flux makes these wastes reach Chascomús Pond during flood periods.Facultad de Ciencias Naturales y Muse

Cambio puntual de la calidad de agua en la laguna Chascomús durante la inundación 2001-2002: “efecto Moisés”

Chascomús pond was affected between June-2001 and September-2002 by two periods of flood events (more than 8 m IGM reference) that had two maximum peaks of nearly 9 m. Such events were studied weekly in surface samples taken in three stations: centre and the zones with influence of the tributaries Vitel (affluent) and Arroyo Girado (effluent). The supply of water promoted a dilution that made the salinity to decrease to one third of the mean value of 1,570 mg/l obtained during 1999-2000. In March-2002 it was registered the maximum value of precipitation (538 mm) that caused the beginning of the second flood period. On March 18 differences were detected between the centre with the other two stations of parameters like salinity (222.5 with respect to 324.9 and 304.1 mg/l), specific conductivity (0.38; 0.55 and 0.56 mS/cm), pH (7.71; 7.94 and 8.00) and agar plate count (31,200; 7,260 and 6,600 UCF/ml). These differences were not detected in the next sampling. The phenomena is tried to explain on the basis of the runoff (physical hypothesis) and by the influence of the groundwater (chemical hypothesis). Because of the occasional separation into different quality of waters such phenomena was called “Moises effect”.Instituto de Limnología "Raúl A. Ringuelet

Nutrientes y clorofila-a durante el período de inundación 2001-2002 en la Laguna Chascomús (Argentina)

Total phosphorus, total nitrogen and chlorophyll-a concentrations were determined weekly in a pelagic zone in Chascomús Pond between April 2001 and September 2002. Two flood periods took part with 8 metres over sea level (IGM) during this time (June- January 2002 and April-June 2002), where in both of them two maximum peaks with about 9 meters were registered. As a consequence a diminution of the salinity to one third of the mean value of 1,57 g.l-1 was observed, because of the dilution promoted by rainwater which was higher in a 40% of the mean 600 mm of the latest five years. Nevertheless, this fact had not occurred with total phosphorus, mean 0,48 mg.l-1, referring to 0,48 mg.l-1 obtained in 1999-2000, while total nitrogen, mean 1,45 mg N.l-1, was nearly in the same order in relation to a previous value of 1,56 mg N.l-1 (1983-1984) and chlorophyll-a, mean 198,2 μg.l-1, showed a significant increment taking into account the concentration of 89,1 μg.l-1 determined during 1999-2002. These results indicate that because of flood events a supply of nutrients reaches the pond coming from wastes of the city (30000 inhabitants), as well as from the effluent of the treatment plant. Normally, the latter go to Girado stream and finally are received by Adela Pond in direction to Salado River, but the inversion of the flux makes these wastes reach Chascomús Pond during flood periods.Facultad de Ciencias Naturales y Muse

Cambio puntual de la calidad de agua en la laguna Chascomús durante la inundación 2001-2002: “efecto Moisés”

Chascomús pond was affected between June-2001 and September-2002 by two periods of flood events (more than 8 m IGM reference) that had two maximum peaks of nearly 9 m. Such events were studied weekly in surface samples taken in three stations: centre and the zones with influence of the tributaries Vitel (affluent) and Arroyo Girado (effluent). The supply of water promoted a dilution that made the salinity to decrease to one third of the mean value of 1,570 mg/l obtained during 1999-2000. In March-2002 it was registered the maximum value of precipitation (538 mm) that caused the beginning of the second flood period. On March 18 differences were detected between the centre with the other two stations of parameters like salinity (222.5 with respect to 324.9 and 304.1 mg/l), specific conductivity (0.38; 0.55 and 0.56 mS/cm), pH (7.71; 7.94 and 8.00) and agar plate count (31,200; 7,260 and 6,600 UCF/ml). These differences were not detected in the next sampling. The phenomena is tried to explain on the basis of the runoff (physical hypothesis) and by the influence of the groundwater (chemical hypothesis). Because of the occasional separation into different quality of waters such phenomena was called “Moises effect”.Instituto de Limnología "Raúl A. Ringuelet

How to explore the sound environment where oral language learning occurs?: a proposal to obtain measurement indicators

El desarrollo del lenguaje oral, ocurre en el íntimo espacio de los hogares humanos, en esta etapa el ambiente acústico cobra especial relevancia, ya que las señales sonoras en interacción con el lenguaje intersubjetivo, van modelando el lenguaje hablado. Actualmente diversas circunstancias han modificado algunas características en las estructuras de cuidado parental; la escucha a través de reproductores, y la implementación de instituciones escolares desde los primeros meses hacen necesario profundizar en este fenómeno. Se encuentra evidencia de que la brecha generada en cuanto a tiempos del aprendizaje del lenguaje, es muy difícil de revertir para los sistemas educacionales. Es necesario mencionar que interacciones protomusicales presentan relación con los mecanismos que activan los procesos en esta etapa. Este trabajo presenta una propuesta para conocer y medir el ambiente sonoro donde ocurre el desarrollo del lenguaje, desde la percepción de los habitantes, dado que existe imposibilidades técnicas y éticas para acceder a este hábitat. Se identificaron 10 factores presentes, y se creó una escala mixta de calificaciones sumadas con ítemes de tipo 'psicofísico' y 'likert'. Se describe a continuación el proceso de construcción y validación de este instrumento, utilizando análisis factorial, análisis de fiabilidad, y correlación con datos del ambiente obtenidos con un 'analizador de espectro audible Phonic PAA (RTA)'. Se aplicó el instrumento a 316 padres de niños no lectores, y se encontró mediante correlaciones bi-variadas entre los factores, evidencia de que el ambiente sonoro tiene influencia en los hábitos y actitudes relacionadas con el mismo.Oral language development occurs in the intimate space of human homes, where the sound environment is especially relevant because sound signals interact with intersubjective language and model spoken language. Evidence indicates that the gap generated in terms of learning times and number of words is very difficult to reverse for educational systems. In addition, different circumstances have modified some characteristics of the sound environment in homes, such as changes in the structures of parental care, listening through music players, and the implementation of school institutions oriented to earlier ages, which make it necessary to deeply understand this stage. Since the existence of technical and ethical impossibilities to access homes, this paper presents a proposal to know and measure the sound environment where language development occurs, based on inhabitants’ perception. Ten factors were identified, and a mixed scale score was created including psychophysical and Likert scaling’s items. The construction and validation of this instrument is described below, using factor analysis, reliability analysis, and correlation with environmental data obtained with a Phonic PAA (RTA) audible spectrum analyzer. This instrument was applied to 316 parents of non-reading children, and it was found that through bi-varied correlations among factors the sound environment influences on the inhabitants’ habits and attitudes related to it.Sociedad Argentina para las Ciencias Cognitivas de la Músic

Field-dependent roughness of moving domain walls in a Pt/Co/Pt magnetic thin film

The creep motion of domain walls driven by external fields in magnetic thin films is described by universal features related to the underlying depinning transition. One key parameter in this description is the roughness exponent characterizing the growth of fluctuations of the domain wall position with its longitudinal length scale. The roughness amplitude, which gives information about the scale of fluctuations, however, has received less attention. Albeit their relevance, experimental reports of the roughness parameters, both exponent and amplitude, are scarce. We report here experimental values of the roughness parameters for different magnetic field intensities in the creep regime at room temperature for a Pt/Co/Pt thin film. The mean value of the roughness exponent is $\zeta = 0.74$, and we show that it can be rationalized as an effective value in terms of the known universal values corresponding to the depinning and thermal cases. In addition, it is shown that the roughness amplitude presents a significant increase with decreasing field. These results contribute to the description of domain wall motion in disordered thin magnetic systems.Comment: 10 pages, 7 figure

Effects of the herbicide Roundup on freshwater microbial communities: a mesocosm study

The impact of the widely used herbicide glyphosate has been mainly studied in terrestrial weed control, laboratory bioassays, and field studies focusing on invertebrates, amphibians, and fishes. Despite the importance of phytoplankton and periphyton communities at the base of the aquatic food webs, fewer studies have investigated the effects of glyphosate on freshwater microbial assemblages. We assessed the effect of the commercial formulation Roundup using artificial earthen mesocosms. The herbicide was added at three doses: a control (without Roundup) and two treatments of 6 and 12 mg/L of the active ingredient (glyphosate). Estimates of the dissipation rate (k) were similar in the two treatments (half-lives of 5.77 and 7.37 d, respectively). The only two physicochemical parameters showing statistically significant differences between treatments and controls were the downward vertical spectral attenuation coefficient kd(λ), where λ is wavelength, and total phosphorus concentration (TP). At the end of the experiment, the treated mesocosms showed a significant increase in the ratio kd(490 nm)/kd(550 nm) and an eightfold increase in TP. Roundup affected the structure of phytoplankton and periphyton assemblages. Total micro- and nanophytoplankton decreased in abundance in treated mesocosms. In contrast, the abundance of picocyanobacteria increased by a factor of about 40. Primary production also increased in treated mesocosms (roughly by a factor of two). Similar patterns were observed in the periphytic assemblages, which showed an increased proportion of dead : live individuals and increased abundances of cyanobacteria (about 4.5-fold). Interestingly, the observed changes in the microbial assemblages were captured by the analysis of the pigment composition of the phytoplankton, the phytoplankton absorption spectra, and the analysis of the optical properties of the water. The observed changes in the structure of the microbial assemblages are more consistent with a direct toxicological effect of glyphosate rather than an indirect effect mediated by phosphorus enrichment.Fil: Pérez, Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas ; ArgentinaFil: Torremorell, Ana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas ; ArgentinaFil: Mugni, Hernan Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología ; ArgentinaFil: Rodriguez, Patricia Laura. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Vera, Maria Solange. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Do Nascimento, Mauro. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Allende, Luz. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bustingorry, Jose Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas ; ArgentinaFil: Escaray, Francisco José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas ; ArgentinaFil: Ferraro, Marcela Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas ; ArgentinaFil: Izaguirre, Irina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Pizarro, Haydee Norma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Bonetto, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología ; ArgentinaFil: Morris, Donald P.. Lehigh University; Estados UnidosFil: Zagarese, Horacio Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas ; Argentin