967 resultados para Continent-arc collision


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Carpeta didáctica para conocer Asia y fomentar actividades positivas ante otras culturas y formas de pensar. Se proponen actividades para trabajar de forma general las características culturales asiáticas (historia, población, razas, economía, política, lenguas, étnias, religiones, arte y el papel de la mujer) y se proporciona información breve de cada país (superficie, población, capital, religión, recursos naturales, renta per cápita, tasa de alfabetización, esperanza de vida, lengua, etc.). Acompañando a esta documentación se complementa con una guía didáctica donde se especifican los objetivos didácticos para cada ciclo de primaria y se describen las actividades específicando el material necesario para llevarlas a cabo. Esta unidad didáctica se puede complementar con material audivisual (exposición 'Asia hoy', montaje de diapositivas, cassette de música asiática autóctona, cuaderno para colorear).

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Unidad didáctica para conocer la cultura asiática y fomentar actitudes positivas ante otras culturas y formas de pensar. Se proponen actividades para trabajar de forma general las características culturales asiáticas (historia, población, razas, economía, política, lenguas, étnias, relegiones, arte y elpapel de la mujer) y se proporciona información breve de cada país (superfície, población, capital, religión, recursos naturales, renta per cápita, tasa de alfabetización, esperanza de vida, lengua, etc.). La unidad didáctica se complementa con una guía didáctica donde se especifican los objetivos didácticas para cada ciclo de Primaria y se describen las actividades especificando el material necesario para llevarlas a cabo. Esta unidad didáctica se puede complementar con material audiovisual (exposición 'Ásia hoy', montaje de diapositivas, etc.). Se incluyen actividades para desarrollar en áreas de conocimiento como Ciencias Sociales, Lengua, Naturales, Ética y Música.

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Resumen tomado de la revista

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El presente documento recoge los textos creados, tanto por ni??osy ni??as como por mayores, para el Taller Intergeneracional Art??stico-Literario organizado por la Concejal??a de la Infancia del Ayuntamiento de Coslada (Madrid). La experiencia tuvo como base el inter??s de que esas generaciones dejen de ser independientes entre si y constituyan una parte activa de la vida social. La cooperaci??n y la creatividad fueron los soportes sobre los que se sustent?? esta idea.

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Programa emitido el 28 de septiembre de 1994

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Publicación cerrada : 1996-2002.

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Se describe una experiencia llevada a cabo en el CEIP Arias Montano (Badajoz) que consisti?? en el uso de un software concreto, el Programa Arc??n, para favorecer la comunicaci??n a trav??s de un soporte digital de un alumno con trastorno de espectro autista escolarizado en segundo curso de primaria. Se observ?? una mejora de la socializaci??n del alumno, de su integraci??n y de su capacidad comunicativa

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Resumen basado en el de la publicaci??n

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Resumen basado en el de la publicaci??n

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New data show that island arc rocks have (Pb-210/Ra-226)(o) ratios which range from as low as 0.24 up to 2.88. In contrast, (Ra-22S/Th-232) appears always within error of I suggesting that the large Ra-226-excesses observed in arc rocks were generated more than 30 years ago. This places a maximum estimate on melt ascent velocities of around 4000 m/year and provides further confidence that the Ra-226 excesses reflect deep (source) processes rather than shallow level alteration or seawater contamination. Conversely, partial melting must have occurred more than 30 years prior to eruption. The Pb-210 deficits are most readily explained by protracted magma degassing. Using published numerical models, the data suggest that degassing occurred continuously for periods up to several decades just prior to eruption but no link with eruption periodicity was found. Longer periods are required if degassing is discontinuous, less than 100% efficient or if magma is recharged or stored after degassing. The long durations suggest much of this degassing occurs at depth with implications for the formation of hydrothermal and copper-porphyry systems. A suite of lavas erupted in 1985-1986 from Sangeang Api volcano in the Sunda arc are characterised by deficits of Pb-210 relative to Ra-226 from which 6-8 years of continuous Rn-222 degassing would be inferred from recent numerical models. These data also form a linear (Pb-210)/Pb-(Ra-226)/Pb array which might be interpreted as a 71-year isochron. However, the array passes through the origin suggesting displacement downwards from the equiline in response to degassing and so the slope of the array is inferred not to have any age significance. Simple modelling shows that the range of (Ra-226)/Pb ratios requires thousands of years to develop consistent with differentiation occurring in response to cooling at the base of the crust. Thus, degassing post-dated, and was not responsible for magma differentiation. The formation, migration and extraction of gas bubbles must be extremely efficient in mafic magma whereas the higher viscosity of more siliceous magmas retards the process and can lead to Pb-210 excesses. A possible negative correlation between (Pb-210/Ra-226)(o) and SO2 emission rate requires further testing but may have implications for future eruptions. (C) 2004 Elsevier B.V. All rights reserved.

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New data show that island arc rocks have (Pb-210/Ra-226)(o) ratios which range from as low as 0.24 up to 2.88. In contrast, (Ra-22S/Th-232) appears always within error of I suggesting that the large Ra-226-excesses observed in arc rocks were generated more than 30 years ago. This places a maximum estimate on melt ascent velocities of around 4000 m/year and provides further confidence that the Ra-226 excesses reflect deep (source) processes rather than shallow level alteration or seawater contamination. Conversely, partial melting must have occurred more than 30 years prior to eruption. The Pb-210 deficits are most readily explained by protracted magma degassing. Using published numerical models, the data suggest that degassing occurred continuously for periods up to several decades just prior to eruption but no link with eruption periodicity was found. Longer periods are required if degassing is discontinuous, less than 100% efficient or if magma is recharged or stored after degassing. The long durations suggest much of this degassing occurs at depth with implications for the formation of hydrothermal and copper-porphyry systems. A suite of lavas erupted in 1985-1986 from Sangeang Api volcano in the Sunda arc are characterised by deficits of Pb-210 relative to Ra-226 from which 6-8 years of continuous Rn-222 degassing would be inferred from recent numerical models. These data also form a linear (Pb-210)/Pb-(Ra-226)/Pb array which might be interpreted as a 71-year isochron. However, the array passes through the origin suggesting displacement downwards from the equiline in response to degassing and so the slope of the array is inferred not to have any age significance. Simple modelling shows that the range of (Ra-226)/Pb ratios requires thousands of years to develop consistent with differentiation occurring in response to cooling at the base of the crust. Thus, degassing post-dated, and was not responsible for magma differentiation. The formation, migration and extraction of gas bubbles must be extremely efficient in mafic magma whereas the higher viscosity of more siliceous magmas retards the process and can lead to Pb-210 excesses. A possible negative correlation between (Pb-210/Ra-226)(o) and SO2 emission rate requires further testing but may have implications for future eruptions. (C) 2004 Elsevier B.V. All rights reserved.

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A multiple factor parametrization is described to permit the efficient calculation of collision efficiency (E) between electrically charged aerosol particles and neutral cloud droplets in numerical models of cloud and climate. The four-parameter representation summarizes the results obtained from a detailed microphysical model of E, which accounts for the different forces acting on the aerosol in the path of falling cloud droplets. The parametrization's range of validity is for aerosol particle radii of 0.4 to 10 mu m, aerosol particle densities of I to 2.0 g cm(-3), aerosol particle charges from neutral to 100 elementary charges and drop radii from 18.55 to 142 mu m. The parametrization yields values of E well within an order of magnitude of the detailed model's values, from a dataset of 3978 E values. Of these values 95% have modelled to parametrized ratios between 0.5 and 1.5 for aerosol particle sizes ranging between 0.4 and 2.0 mu m, and about 96% in the second size range. This parametrization speeds up the calculation of E by a factor of similar to 10(3) compared with the original microphysical model, permitting the inclusion of electric charge effects in numerical cloud and climate models.

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Previous studies using the Hadley Centre coupled model (HadCM3) have shown that the islands of the Maritime Continent act as an unrealistic block to the eastward propagation of the Madden-Julian Oscillation (MJO). This blocking effect is investigated using a simplified, aqua-planet version of this GCM, with various idealized configurations of the Maritime Continent islands placed on the equator, and an MJO-like convective signal forced by a propagating sea-surface temperature anomaly dipole. Results suggest that it is the orography of the islands, rather than the presence of the islands themselves, which results in the blocking of the MJO. Although the peak elevation of the orography in the GCM is very much lower than in reality, it appears to act as effective block to the eastward propagation of the low-level Kelvin wave signal which accompanies the MJO. In particular, the representation of Sumatra in the GCM, as a north-south oriented ridge straddling the equator, seems to be particularly effective at blocking the Kelvin wave signal, which in a full GCM would result in the weakening or complete extinction of the MJO signal to the east of the Maritime Continent.