Nucleation of oscillons

This study concerns the birth of oscillons, the subharmonic localized excit ations observed in vibrated sand. To this end, we have constructed a dynami cal model based on nearest pattern interaction approximation. The model adm its an oscillon solution and features its nucleation process. It is argued here that oscillons are created through nucleation rather than growing from linearly unstable modes. The physical implication of the nucleation in pat tern formation is discussed briefly. [S1063-651X(99)09601-4].