Silver and platinum-catalysed addition of O–H and N–H bonds to allenes

Transition-metal catalysed nucleophile addition to allenes is a very powerful tool for the synthesis of functionalised molecules containing heteroatoms, heterocycles in the intramolecular version, or allyl derivatives in the intermolecular version. The reaction has been explored with a wide variety of metals, silver being one of the most effective. Although platinum has somehow been less explored, different reactivities have been observed with this metal, showing the great potential and versatility of this methodology. This review will highlight the reactions with these two metals, silver and platinum, when oxygen or nitrogen nucleophiles are employed. Although most of the examples describe the intramolecular version, some intermolecular reactions with platinum have been described, and will also be covered

The Contribution of Railways to Economic Growth in Latin America before 1914: the cases of Mexico, Brazil and Argentina

This paper presents preliminary estimates of the contribution of the railway technology to GDP growth in Argentina, Brazil and Mexico before 1914, and compares them with the available figures for two European economies (Britain and Spain). The results of the estimation indicate that the growth contribution of railways was substantially higher in those three Latin American economies than in Britain or Spain, although in Argentina and Mexico that high contribution was disguised behind the fast growth of the aggregate economy. This result is interpreted as a sign of the central role that the railways performed in the export-led growth episode of those three economies.railways, Latin America, Growth Contribution, Internal Transport, Export-Led Growth

The family of quaternionic quasi-unitary Lie algebras and their central extensions

The family of quaternionic quasi-unitary (or quaternionic unitary Cayley--Klein algebras) is described in a unified setting. This family includes the simple algebras sp(N+1) and sp(p,q) in the Cartan series C_{N+1}, as well as many non-semisimple real Lie algebras which can be obtained from these simple algebras by particular contractions. The algebras in this family are realized here in relation with the groups of isometries of quaternionic hermitian spaces of constant holomorphic curvature. This common framework allows to perform the study of many properties for all these Lie algebras simultaneously. In this paper the central extensions for all quasi-simple Lie algebras of the quaternionic unitary Cayley--Klein family are completely determined in arbitrary dimension. It is shown that the second cohomology group is trivial for any Lie algebra of this family no matter of its dimension.Comment: 17 pages, LaTe

The contribution of railways to economic growth in Latin America before 1914: a growth accounting approach

Railways are usually considered as one of the most important innovations that fostered the transition of Latin America to economic growth before 1914. The social saving estimates that are available for several Latin American countries seem to confirm that view. However, the interpretation of the results of the social saving literature is not straightforward, since the comparison among social savings calculated for different countries and years may be troublesome, and the actual meaning of the social saving estimates is not clear. This paper suggests an alternative approach to the economic impact of railways in Latin America. It presents estimates of the direct growth contribution of the railway technology in Argentina, Brazil, Mexico and Uruguay before 1914, which are calculated on the basis of the growth accounting methodology. The outcomes of the estimation indicate that railway effects on Uruguayan economic growth were very low. By contrast, in the other three cases under study (Argentina, Mexico and Brazil) the railways provided huge direct benefits. In Argentina and Mexico, these amounted to between one fifth and one quarter of the total income per capita growth of the period under analysis. By contrast, in the case of Brazil, the outcomes of the analysis indicate that the direct contribution of railways to growth would have been higher than the whole income per capita growth of the Brazilian economy before 1914. This unexpected result might suggest that the national level is not the most adequate scale to analyse the economic impact of network infrastructure in the case of large, geographically unequal and insufficiently integrated developing economies.Railways; Latin America; Economic Growth