In this study we investigate the relation between stellar mass, dust extinction and star formation rate (SFR) using ∼ 150, 000 star-forming galaxies from the SDSS DR7. We show that the relation between dust extinction and SFR changes with stellar mass. For galaxies at the same stellar mass dust extinction is anti-correlated with the SFR at stellar masses < 10M⊙. There is a sharp transition in t...

In the last few years a number of authors have suggested that evolution may be a so-called self-organized critical phenomenon, and that critical processes might have a significant effect on the dynamics of ecosystems. In particular it has been suggested that mass extinction may arise through a purely biotic mechanism as the result of "coevolutionary avalanches". In this paper we first explore t...

Introducing the effect of extinction into the so-called replicator equations in mathematical biology, we construct a general model of ecosystems. The present model shows mass extinction by its own extinction dynamics when the system initially has a large number of species (diversity). The extinction dynamics shows several significant features such as a power law in basin size distribution, indu...

Mass extinctions are dramatic features of the fossil record in which extinction risk is substantially elevated above background levels. Although extinction risk varies markedly over geologic time, as well as geographically, it was particularly elevated and global in extent during the so-called Big Five events: the Late Ordovician, Late Devonian, end-Permian, end-Triassic, and end-Cretaceous (1)...

The end Permian extinction was the greatest mass extinction of the Phanerozoic Era. It impacted marine and terrestrial plants and animals. Although the rate of the extinction has been controversial in the past, recent evidence suggests that the extinction progressed in two pulses approximately 5-12 million years apart. The second pulse of the extinction is marked by a sharp temperature spike an...