http://sasakitakanori.com/en Planetary Scientist at Tokyo Tech Mon, 29 Sep 2008 07:50:41 +0000 http://backend.userland.com/rss092 en In this study, on the basis of the assumption of "random-way" and "size-dependent-chosen" evolution, we reconsider an evolving food web model and discuss the mechanism of diversification, stabilization, and extinction of species. By adopting the size-dependent evolutionary system, we derived a particular evolutionary pattern of the diversity that maintained ... http://sasakitakanori.com/en/archives/16 Hf-W chronometry provides constraints on the timing of planetary accretion and differentiation, as segregation of a metal core from silicates should induce strong fractionation of Hf from W. In previous studies, it was assumed that a giant impact raise up perfect resetting on Hf-W chronometer. In this study, ... http://sasakitakanori.com/en/archives/14 Several previous observations of Pluto in the J, H, and K bands have derived its surface composition of mixture ice of N2, CH4, and CO. Hydrocarbons generally have a fundamental C-H stretching mode in the L band (2.8 - 4.0 um), the absorption of which is much stronger than ... http://sasakitakanori.com/en/archives/11 "Space weathering" is the term applied to darkening albedo, reddening spectral slope, and obscuring absorption bands of planetary surface materials with time. The mismatch between reflectance spectra of most common asteroids (S-type asteroids) and most common meteorites (ordinary chondrites) might be caused by the space weathering. Recent laboratory ... http://sasakitakanori.com/en/archives/8