Close to the onset of an instability, it is expected that fluctuations can play a role. In general, fluctuations act additively (broadly speaking, their effect do not depend on the amplitude of the unstable field) and are responsible for a variety of effects such as the well known anomalous critical exponents of equilibrium phase transition.
　In out of equilibrium systems, fluctuations can be multiplicative: their effect vanish when the amplitude of the unstable mode is zero. Several new effects appear. During this seminar I will discuss in particular two topics: what happen to the onset (is it still defined, how to calculate it)? and what happen above onset (focussing on the so-called on-off intermittent regime).
　The presented results will be illustrated with examples in the context of instabilities in fluid dynamics and magneto hydrodynamics.


連絡教員　物理学系　竹内　一将（内線2298）