Before revision:  In recent years, research on Physarum  has become more popular after Nakagaki et al. (2000) performed his famous experiments showing that Physarum was able to find the shortest route through a maze.
After revision:  In recent years, research on Physarum has become more popular after Nakagaki et al. (2000) performed their famous experiment showing that Physarum was able to find the shortest route through a maze.