Papel de la historia en Une vie de Saint de Roger Martin du Gard

Roger Martin du Gard, como su héroe Antoine Thibault, nace en 1881, coincidiendo con los primeros años de la Tercera República. La bistotia de su tiempo, los acontecimientos que la configuran desempeñan un papel muy importante a lo largo de su obra. Martin du Gard es reacio a describir momentos históricos que no ha podido vivir directamente. Le gusta novelar sobre la base de hechos acaecidos en el tiempo en que vive. Así, todas sus obras publicadas se desarrollan teniendo como telón de fondo el acontecer histórico contemporáneo. Unicamente en una de sus primeras novelas inacabadas e inéditas, fine vie de Sainí, evoca la guerra con la que culmina el Segundo Imperio, que encuentra su fin en el desastre de Sedán. El ambiente social, los hechos históricos descritos en la ficción novelesca coinciden plenamente con los acontecimientos reales que tuvieran lugar durante la vida del autor.

Fleuve de Kemi : dessiné par A. F. Skjöldebrand ; gravé par J. F. Martin

Digitoitu valokuvasta, joka on julkaistu kirjassa: R. Knapas & P. Koistinen, Historiallisia kuvia, 1993.

Thomas-Fermi theory for atomic nuclei revisited

The recently developed semiclassical variational Wigner-Kirkwood (VWK) approach is applied to finite nuclei using external potentials and self-consistent mean fields derived from Skyrme inter-actions and from relativistic mean field theory. VWK consist s of the Thomas-Fermi part plus a pure, perturbative h 2 correction. In external potentials, VWK passes through the average of the quantal values of the accumulated level density and total en energy as a function of the Fermi energy. However, there is a problem of overbinding when the energy per particle is displayed as a function of the particle number. The situation is analyzed comparing spherical and deformed harmonic oscillator potentials. In the self-consistent case, we show for Skyrme forces that VWK binding energies are very close to those obtained from extended Thomas-Fermi functionals of h 4 order, pointing to the rapid convergence of the VWK theory. This satisfying result, however, does not cure the overbinding problem, i.e., the semiclassical energies show more binding than they should. This feature is more pronounced in the case of Skyrme forces than with the relativistic mean field approach. However, even in the latter case the shell correction energy for e.g.208 Pb turns out to be only ∼ −6 MeV what is about a factor two or three off the generally accepted value. As an adhoc remedy, increasing the kinetic energy by 2.5%, leads to shell correction energies well acceptable throughout the periodic table. The general importance of the present studies for other finite Fermi systems, self-bound or in external potentials, is pointed out.

Climate change impacts on lakes: an integrated ecological perspective based on a multi-faceted approach, with special focus on shallow lakes

Freshwater ecosystems and their biodiversity are presently seriously threatened by global development and population growth, leading to increases in nutrient inputs and intensification of eutrophication-induced problems in receiving fresh waters, particularly in lakes. Climate change constitutes another threat exacerbating the symptoms of eutrophication and species migration and loss. Unequivocal evidence of climate change impacts is still highly fragmented despite the intensive research, in part due to the variety and uncertainty of climate models and underlying emission scenarios but also due to the different approaches applied to study its effects. We first describe the strengths and weaknesses of the multi-faceted approaches that are presently available for elucidating the effects of climate change in lakes, including space-for-time substitution, time series, experiments, palaeoecology and modelling. Reviewing combined results from studies based on the various approaches, we describe the likely effects of climate changes on biological communities, trophic dynamics and the ecological state of lakes. We further discuss potential mitigation and adaptation measures to counteract the effects of climate change on lakes and, finally, we highlight some of the future challenges that we face to improve our capacity for successful prediction.