883 resultados para Juan María Songel


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96 p. : il.

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Juan F. Alcina, Emilio Blanco, Pedro M. Cátedra, Javier Cercas, José María Micó, Rafael Ramos e Íñigo Ruiz Arzálluz con textos de Eugenio Asensio, Juan Benet, Fernando Lázaro Carreter y José-Carlos Mainer

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Nivel educativo: Grado. Duración (en horas): Más de 50 horas

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Detailed oxygen, hydrogen and carbon isotope studies have been carried out on igneous and metamorphic rocks of the Stony Mountain complex, Colorado, and the Isle of Skye, Scotland, in order to better understand the problems of hydrothermal meteoric water-rock interaction.

The Tertiary Stony Mountain stock (~1.3 km in diameter), is composed of an outer diorite, a main mass of biotite gabbro, and an inner diorite. The entire complex and most of the surrounding country rocks have experienced various degrees of 18O depletion (up to 10 per mil) due to interaction with heated meteoric waters. The inner diorite apparently formed from a low-18O magma with δ18O ≃ +2.5, but most of the isotopic effects are a result of exchange between H2O and solidified igneous rocks. The low-18O inner diorite magma was probably produced by massive assimilation and/or melting of hydrothermally altered country rocks. The δ18O values of the rocks generally increase with increasing grain size, except that quartz typically has δ18O = +6 to +8, and is more resistant to hydrothermal exchange than any other mineral studied. Based on atom % oxygen, the outer diorites, gabbros, and volcanic rocks exhibit integrated water/rock ratios of 0.3 ± 0.2, 0.15 ± 0.1, and 0.2 ± 0.1, respectively. Locally, water/rock ratios attain values greater than 1.0. Hydrogen isotopic analyses of sericites, chlorites, biotites, and amphiboles range from -117 to -150. δD in biotites varies inversely with Fe/Fe+Mg, as predicted by Suzuoki and Epstein (1974), and positively with elevation, over a range of 600 m. The calculated δD of the mid-to-late-Tertiary meteoric waters is about -100. Carbonate δ13C values average -5.5 (PDB), within the generally accepted range for deep-seated carbon.

Almost all the rocks within 4 km of the central Tertiary intrusive complex of Skye are depleted in 18O. Whole-rock δ18O values of basalts (-7. 1 to +8.4), Mesozoic shales (-0.6 to + 12.4), and Precambrian sandstones (-6.2 to + 10.8) systematically decrease inward towards the center of the complex. The Cuillin gabbro may have formed from a 18O-depleted magma (depleted by about 2 per mil); δ18O of plagioclase (-7.1 to + 2.5) and pyroxene (-0.5 to + 3.2) decrease outward toward the margins of the pluton. The Red Hills epigranite plutons have δ18O quartz (-2.7 to + 7.6) and feldspar (-6.7 to + 6.0) that suggest about 3/4 of the exchange took place at subsolidus temperatures; profound disequilibrium quartz-feldspar fractionations (up to 12) are characteristic. The early epigranites were intruded as low-18O melts (depletions of up to 3 per mil) with δ18O of the primary, igneous quartz decreasing progressively with time. The Southern Porphyritic Epigranite was apparently intruded as a low-18O magma with δ18O ≃ -2.6. A good correlation exists between grain size and δ18O for the unique, high-18O Beinn an Dubhaich granite which intrudes limestone having a δ18O range of +0.5 to +20.8, and δ13C of -4.9 to -1.0. The δD values of sericites (-104 to -107), and amphiboles, chlorites, and biotites (-105 to -128) from the igneous rocks , indicate that Eocene surface waters at Skye had δD ≃ -90. The average water/rock ratio for the Skye hydrothermal system is approximately one; at least 2000 km3 of heated meteoric waters were cycled through these rocks.

Thus these detailed isotopic studies of two widely separated areas indicate that (1) 18O-depleted magmas are commonly produced in volcanic terranes invaded by epizonal intrusions; (2) most of the 18O-depletion in such areas are a result of subsolidus exchange (particularly of feldspars); however correlation of δ18O with grain size is generally preserved only for systems that have undergone relatively minor meteoric hydrothermal exchange; (3) feldspar and calcite are the minerals mos t susceptible to oxygen isotopic exchange, whereas quartz is very resistant to oxygen isotope exchange; biotite, magnetite, and pyroxene have intermediate susceptibilities; and (4) basaltic country rocks are much more permeable to the hydrothermal convective system than shale, sandstone, or the crystalline basement complex.

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In this work we study the gender segregation in technological undergraduate studies in the University of The Basque Country (UPV/EHU). For this study we use the data of new admissions at the UPV/EHU. They are from the time period of the years 2003-2013. We focus on the first and last year to check if the segregation has changed over these ten years. We build segregation curves within the Lorenz approach. Our results show that the gender segregation in technological undergraduate studies in the University of the Basque Country has increased over the last ten years. We also show that the distribution between men and women has changed.  

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10 cartas (mecanografiadas); entre 210x255mm y 210x310mm. [La carta fechada el 10-11-1942 esta incompleta, falta la primera hoja]

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11 cartas (mecanografiadas y manuscritas); entre 170x225mm y 215x275mm

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El objetivo de este trabajo es sintetizar nanopartículas de magnetita con grupos hidroxilo y con grupos amino, y estudiar el uso de ambas en la cosecha de dos especies distintas de microalgas creciendo con distintas fuentes de nitrógeno.

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8 cartas (mecanografiadas y manuscritas); entre 150x210mm y 215x275mm .- 1 Felicitación de Navidad (manuscrita y sin fecha) ; 110mmx160mm

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Cap. 1. Museos y patrimonio: de la distancia retórica a la interlocución democrática. Iñaki Díaz Balerdi. Cap. 2. Au coeur des conflits entre memoire, histoire et developpement economique, les nouveaux enjeux des musees de société aujourd’hui. François Hubert. Cap. 3. Elites, Instituciones Públicas, identidad cultural y turismo en los orígenes del Museo Municipal de Donostia-San Sebastián. Iñaki Arrieta Urtizberea. Cap. 4. Los orígenes de la museografía etnográfica en Cataluña: el Arxiu-Museu Folklòric de Ripoll. Oriol Beltran Costa. Cap. 5. Museo de la Pesca en Palamós: espacio para la memoria de los pescadores. Miquel Martí i Llambrich. Cap. 6. Arqueología y museos en Gipuzkoa; las experiencias del Centro de Estudios ARKEOLAN (1986-2005). Mª Mercedes Urteaga Artigas. Cap. 7. Penser un Musée des Confluences: un autre discours sur soi et les autres que soi. Thierry Valentin. Cap. 8. Turismo cultural y museos: oportunidades de desarrollo comunes. El caso de Cesis, Letonia. María Fernández Sabau. Cap. 9. La gestión y el uso turístico de los museos: la experiencia de Barcelona. Jordi Juan Tresserras y Juan Carlos Matamala. Cap. 10. Museos, turismo y desarrollo local en el norte de Portugal: el Ecomuseo del Barroso. Xerardo Pereiro. Cap. 11. Turismo y patrimonio cultural en las pequeñas y medianas ciudades: el Barri Vell de Girona y el Museu d’Art de Girona. Josep Manuel Rueda Torres.

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Los enzimas son piezas fundamentales en el correcto funcionamiento de cualquier sistema biológico. Gracias a su naturaleza proteica y a las estructuras tridimensionales complejas que son capaces de adoptar, estas moléculas actúan como catalizadores de reacciones químicas. L a función de los enz imas es disminuir la energía de activación de la reacción, aumentando de este modo la velocidad de reacción. L o s enzimas no alteran el balance e nergético de las reacciones en que intervienen, ni modifican, por lo tanto, el equilibrio de la reacción . Por este motivo, en las reacciones catalizadas por enzimas se observa una mayor rapidez a la hora de alcanzar el equilibrio. La ciencia que estudia l a velocidad de las reacciones químicas que son catalizadas por enzimas es la cinética enzimática , e n la cual , las moléculas sobre las que actúan los enzimas se denominan sustratos y las moléculas resultantes de la conversión productos. El estudio de la cin ética de un enzima permite explicar los detalles de su mecanismo catalítico, su papel en el metabolismo o incluso cómo se controla su actividad en la célula. Las dos propiedades más importantes a la hora de trabajar con enzimas son: el tiempo que tarda en saturarse con un sustrato en particular y la velocidad máxima de reacción que puede alcanzar. Para el estudio de estas propiedades en el laboratorio se realizan los ensayos enzimáticos. El procedimiento a seguir en estos casos es medir la aparición de un producto o la desaparición de un sustrato frente al tiempo.