We investigate the topological properties of N(N⩾1) disclination lines in cholesteric liquid crystals. The topological structure of N disclination lines is obtained with the Hopf index and Brouwer degree. Furthermore, the knotted χ disclination loops is proposed with the Hopf invariant. And...

Humans often behave discriminatorily towards others depending on their group membership. In this work, we establish a spatial Prisoner’s dilemma model to investigate the relation between tag-mediated discrimination and cooperation. By introducing tag-mediated selective interaction, we find...