Before revision:  The approach in these studies is called topological data analysis , and it has been used to study the branching structures of veins in leaves, how people vote in elections, flight patterns in models of bird flocking, and more.
After revision:  The approach in these studies is called 'topological data analysis' , and it has been used to study the branching structures of veins in leaves, how people vote in elections, flight patterns in models of bird flocking, and more.