998 resultados para 41-369


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Handwritten on verso: zu obest mein Atelier (My studio on the top floor)

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Aluminium iodide reduces sulphonyl chlorides to disulphides and sulphoxides to sulphides under mild conditions in acetonitrile.

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Handwritten on verso: zu obest mein Atelier (My studio on the top floor)

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Mesoporous MCM-41 type silicas containing molybdenum and cobalt have been prepared with pore sizes in the range 30-38 Angstrom and 54-59 Angstrom. Catalytic properties of these materials have been examined with respect to the oxidation of cyclooctene and aniline.

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The short-lived radionuclide Ca-41 plays an important role in constraining the immediate astrophysical environment and the formation timescale of the nascent solar system due to its extremely short half-life (0.1 Myr). Nearly 20 years ago, the initial ratio of Ca-41/Ca-40 in the solar system was determined to be (1.41 +/- 0.14) x 10(-8), primarily based on two Ca-Al-rich Inclusions (CAIs) from the CV chondrite Efremovka. With an advanced analytical technique for isotopic measurements, we reanalyzed the potassium isotopic compositions of the two Efremovka CAIs and inferred the initial ratios of Ca-41/Ca-40 to be (2.6 +/- 0.9) x 10(-9) and (1.4 +/- 0.6) x 10(-9) (2 sigma), a factor of 7-10 lower than the previously inferred value. Considering possible thermal processing that led to lower Al-26/Al-27 ratios in the two CAIs, we propose that the true solar system initial value of Ca-41/Ca-40 should have been similar to 4.2 x 10(-9). Synchronicity could have existed between Al-26 and Ca-41, indicating a uniform distribution of the two radionuclides at the time of CAI formation. The new initial Ca-41 abundance is 4-16 times lower than the calculated value for steady-state galactic nucleosynthesis. Therefore, Ca-41 could have originated as part of molecular cloud materials with a free decay time of 0.2-0.4 Myr. Alternative possibilities, such as a last-minute input from a stellar source and early solar system irradiation, could not be definitively ruled out. This underscores the need for more data from diverse CAIs to determine the true astrophysical origin of Ca-41.

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Three refractory coarse grained CAIs from the Efremovka CV3 chondrite, one (E65) previously shown to have formed with live Ca-41, were studied by ion microprobe for their Al-26-Mg-26 and Be-10-B-10 systematic in order to better understand the origin of Be-10. The high precision Al-Mg data and the inferred Al-26/Al-27 values attest that the precursors of the three CAIs evolved in the solar nebula over a period of few hundred thousand years before last melting-crystallization events. The initial Be-10/Be-9 ratios and delta B-10 values defined by the Be-10 isochrons for the three Efremovka CAIs are similar within errors. The CAI Be-10 abundance in published data underscores the large range for initial Be-10/Be-9 ratios. This is contrary to the relatively small range of Al-26/Al-27 variations in CAIs around the canonical ratio. Two models that could explain the origin of this large Be-10/Be-9 range are assessed from the collateral variations predicted for the initial delta B-10 values: (i) closed system decay of Be-10 from a ``canonical'' Be-10/Be-9 ratio and (ii) formation of CAIs from a mixture of solid precursors and nebula gas irradiated during up to a few hundred thousand years. The second scenario is shown to be the most consistent with the data. This shows that the major fraction of Be-10 in CAIs was produced by irradiation of refractory grains, while contributions of galactic cosmic rays trapping and early solar wind irradiation are less dominant. The case for Be-10 production by solar cosmic rays irradiation of solid refractory precursors poses a conundrum for Ca-41 because the latter is easily produced by irradiation and should be more abundant than what is observed in CAIs. Be-10 production by irradiation from solar energetic particles requires high Ca-41 abundance in early solar system, however, this is not observed in CAIs. (C) 2013 Elsevier B.V. All rights reserved.

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A large-eddy simulation with transitional structure function(TSF) subgrid model we previously proposed was performed to investigate the turbulent flow with thermal influence over an inhomogeneous canopy, which was represented as alternative large and small roughness elements. The aerodynamic and thermodynamic effects of the presence of a layer of large roughness elements were modelled by adding a drag term to the three-dimensional Navier-Stokes equations and a heat source/sink term to the scalar equation, respectively. The layer of small roughness elements was simply treated using the method as described in paper (Moeng 1984, J. Atmos Sci. 41, 2052-2062) for homogeneous rough surface. The horizontally averaged statistics such as mean vertical profiles of wind velocity, air temperature, et al., are in reasonable agreement with Gao et al.(1989, Boundary layer meteorol. 47, 349-377) field observation (homogeneous canopy). Not surprisingly, the calculated instantaneous velocity and temperature fields show that the roughness elements considerably changed the turbulent structure within the canopy. The adjustment of the mean vertical profiles of velocity and temperature was studied, which was found qualitatively comparable with Belcher et al. (2003, J Fluid Mech. 488, 369-398)'s theoretical results. The urban heat island(UHI) was investigated imposing heat source in the region of large roughness elements. An elevated inversion layer, a phenomenon often observed in the urban area (Sang et al., J Wind Eng. Ind. Aesodyn. 87, 243-258)'s was successfully simulated above the canopy. The cool island(CI) was also investigated imposing heat sink to simply model the evaporation of plant canopy. An inversion layer was found very stable and robust within the canopy.

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Contenido: El desarrollo de la comunidad internacional como introducción al estudio del Derecho Internacional Público / Alfredo M. de las Carreras – Las grandes transformaciones del Derecho Administrativo / Juan Carlos Cassagne – La convivencia humana y la ley moral, la verdad y la justicia en la ordenación de las relaciones internacionales : a 32 años de la Pacem in terris de S. S. Juan XXIII / José A. Giménez Rébora – El poder internacional en el Mercosur / Eduardo A. Clariá – Tratamiento del leasing en la Ley de Quiebras / Eduardo A. Barreira Delfino – La defensa nacional es cosa de todos / Emilio Barquet – Contrato de locación de vientres : nuevos proyectos de ley / Dora Rocío Laplacette – La formación del pensamiento nacional ruso / Florencio Hubeñak – Notas bibliográficas

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Contenido: Filosofía y Teología en el tomismo / La Dirección – Gérmenes de idealismo en las “Investigaciones lógicas” de Husserl / Juan A. Casaubón – La materia inteligible / Emilio Mondelli – El estoicismo y su teoría del hombre / Benito R. Raffo Magnasco -- Bibliografía

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Contenido: Nota preliminar – Poesía mariana en Gonzalo de Berceo / Lía N. Uriarte Rebaudi – El judío y el diablo como “otro” en los Milagros de Nuestra Señora de Berceo / Heanon M. Wilkins – “Intellectum tibi dabo et instruam te” / Eric Naylor – Descripción, narración, argumentación y crisis de la oralidad en el Libro del Buen Amor / Sofía M. Carrizo Rueda – El poema de Alfonso XI: ¿Un eco priscilianista, sabeliano, patripasiano? / Jorge Norberto Ferro – El vino en el refranero español; concordancias / Dolly M. Lucero Ontiveros – Una propuesta de clasificación de la Literatura Sapiencial Hispánica en el siglo XIII / Alicia E. Ramadori – Fray Juan García de Castrojeriz receptor de Aristóteles / Hugo Oscar Bizzarri – La especificidad de la prosa alfonsí; el caso del Lapidario / Mirta G. Aguayo – Alfonso el Sabio y Brunetto Latini: convergencias / Gretchem Arnstedt de Magneres – La figura autoral de Alfonso X en las Cantigas de Santa María / Santiago Aníbal Disalvo – La historia del rey Guillermo de Inglaterra: del relato del siglo XIV a la crónica quinientista / Carina Alejandra Zubillaga – El prólogo de “El Victorial”: heterogeneidad y orden a favor de una adecuada recepción / María Mercedes Rodríguez Temperley – A propósito del prólogo de la Confesión del amante / María Cristina Balestrini – Función de la “ekprhasis” en los relatos caballerescos / Lilia Elda Ferrario de Orduna – Una nueva fuente del Amadís de Gaula primitivo: la Waltbarii poesis del abad Ekkehard I. de Saint Gall / Aquilino Suárez Pallasá – Profecía mesiánica y profecía apocalíptica: la cuestión constantinopolitana en las Sergas de Esplandián y Primaleón / Javier Roberto González – Dos romances sefardíes de incógnito en una colección de romances. Aporte de nuevas versiones / Eleonora Angélica Alberti de Kleinbort – Conjeturas acerca del original manuscrito de la Comedia de Fernando Rojas / Germán Orduna – Fernando de Rojas, ¿autor? / Joseph Thomas Snow – El fondo medieval de la colección Foulché-Delbosc / Georgina Olivetto – Nómina de todos los congresistas

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O projeto de Constituição já aprovado nas etapas anteriores da Constituinte prevê eleições presidenciais no próximo ano. A decisão foi tomada numa sessão histórica da Comissão de Sistematização. O autor da emenda dos 4 anos acredita que a vitória se repetirá no Plenário. Contra os 4 anos existem 2 obstáculos: Um é o próprio Presidente Sarney, após ter definido seu mandato em 4 anos, mudou para 5 anos. O outro obstáculo é o tempo. O Plenário da Constituinte ainda não começou. Os mais otimistas acham que as votações começam em final de janeiro. Com isto, não há previsão de quando ficará pronta a nova Carta. Dois fatores importantes poderão ser levados em conta pela Constituinte: a crise econômica e a vontade de mudar. A vontade popular parece pedir 4 anos e eleições diretas em 1988.

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The problem of the peculiar reproductive biology of the cladoceran Daphnia middendorffiana is investigated from a cytological viewpoint, and by direct observation the meiotic phenomena of the eggs both subitaneous and resting is studied. and during maturation, the true mechanism of the succession of reproductive phases of different ecological significance. Samples were collected in the Italian Alpine Lake of Campo 4°.

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With the aid of the German Research Association in the central programme 'Sand movements in the German coastal region', an investigation into the current conditions in the shallow water areas of the coasts of the south-eastern North Sea between Sylt and the Weser estuary was carried out by the author. Foundations of the work are 19 continuous current recordings in five profiles normal to the coast from years 1971 to 1973. Off the coasts of the south-eastern North Sea varying tidal currents impinge; they are currents whose directions may vary periodically through all points of the compass. They are caused by the circulating tides in the North Sea (Amphidromien). The turning flow movement experiences a deformation in the very shallow coastal waters, and as it happens the flow turning movement in the case of high tide continues right up onto the outer flats, while here and in the fore-lying shallow water areas around the time of low water (on account of the small depths of waters), there prevails a more variable current. A result of this hydrodynamical procedure is the development of counter currents. This partial translation of the original paper provides the summary of this study of of the mudflat areas between the Elbe and Weser.