title: Inwardly rotating spirals in nonuniform excitable media.
abstract: Inwardly rotating spirals (IRSs) have attracted great attention since their observation in an oscillatory reaction-diffusion system. However, IRSs have not yet been reported in planar excitable media. In the present work we investigate rotating waves in a nonuniform excitable medium, consisting of an inner disk part surrounded by an outer ring part with different excitabilities, by numerical simulations of a simple FitzHugh-Nagumo model. Depending on the excitability of the medium as well as the inhomogeneity, we find the occurrence of IRSs, of which the excitation propagates inwardly to the geometrical spiral tip.
authors.affiliation: Zhejiang Institute of Modern Physics and Department of Physics, Zhejiang University, Hangzhou 310027, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
authors.forename: Xia
authors.initials: X
authors.lastname: Feng
authors.forename: Mei-chun
authors.initials: MC
authors.lastname: Cai
authors.forename: Bing-wei
authors.initials: BW
authors.lastname: Li
authors.forename: He-ping
authors.initials: HP
authors.lastname: Ying
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang