Sang Il Kim

Peut-on tenter une nouvelle approche de Descartes? Penser philosophiquement la notion de creation, c'est la traduire dans le registre des quatre causes: ainsi la cause efficiente relie et separe a la fois le createur et le cree; mais Dieu est aussi cause formelle, ce qui sauve la continuite entre l'auteur et son ouvrage. Cette continuite se nomme analogie et cette analogie assure l'autonomie de la pensee finie. Ce transfert d'autorite dans la production meme, particulierement manifeste chez Descartes, permet de comprendre la devolution a l'homme d'un certain pouvoir createur. L'agir humain peut etre inaugural. L'est-il en matiere de philosophie? La dette de Descartes envers la scolastique tardive semble indiquer qu'on ne pense qu'a partir de ce qu'on herite. L'ambivalence de la notion de creation ne nous permettrait-elle pas cependant de montrer que le commencement dans la pensee reste a tout moment possible? Telle pourrait etre l'explication du radicalisme cartesien.

© 2016, Nature Publishing Group. All rights reserved.The interaction between two different materials can present novel phenomena that are quite different from the physical properties observed when each material stands alone. Strong electronic correlations, such as magnetism and superconductivity, can be produced as the result of enhanced Coulomb interactions between electrons. Two-dimensional materials are powerful candidates to search for the novel phenomena because of the easiness of arranging them and modifying their properties accordingly. In this work, we report magnetic effects in graphene, a prototypical non-magnetic two-dimensional semi-metal, in the proximity with sulfur, a diamagnetic insulator. In contrast to the well-defined metallic behaviour of clean graphene, an energy gap develops at the Fermi energy for the graphene/sulfur compound with decreasing temperature. This is accompanied by a steep increase of the resistance, a sign change of the slope in the magneto-resistance between high and low fields, and magnetic hysteresis. A possible origin of the observed electronic and magnetic responses is discussed in terms of the onset of low-temperature magnetic ordering. These results provide intriguing insights on the search for novel quantum phases in graphene-based compounds.

© Author 2014.We use a 3-D regional atmospheric chemistry transport model to examine ozone dry deposition in East Asia, which is an important but uncertain research area because of insufficient observation and numerical studies focusing on East Asia. Here we compare two widely used dry deposition parameterization schemes, the Wesely and M3DRY schemes, which are used in the WRF-Chem and Community Multiscale Air Quality models, respectively. Simulated ozone dry deposition velocities with the two schemes under identical meteorological conditions show considerable differences owing to surface resistance parameterization discrepancies. Resulting ozone concentrations differ by up to 10 ppbv for a monthly mean in May when the peak ozone typically occurs in East Asia. An evaluation of the simulated dry deposition velocities shows that the Wesely scheme calculates values with more pronounced diurnal variation than the M3DRY and results in a good agreement with the observations. However, we find significant changes in simulated ozone concentrations using the Wesely scheme but with different surface type data sets, indicating the high sensitivity of ozone deposition calculations to the input data. The need is high for observations to constrain the dry deposition parameterization and its input data to improve the use of air quality models for East Asia.