As the world becomes increasingly connected, the need to ensure the proper functioning of its many underlying networks -- such as the Internet, power grids, global air transportation and ecological networks -- also is increasing. But controlling networks is very difficult. Now a Northwestern University research team has developed the first broadly applicable computational approach identifying interventions that can both rescue complex networks from the brink（边缘） of failure and reprogram them to a desired task.

"A fundamental property of networks is that a perturbation（扰乱，不安） to one node can affect other nodes, potentially causing the entire system to change behavior or fail," said Adilson E. Motter, who supervised the research. "We have turned this principle on its head for something positive: to control network behavior. This novel approach to control could have a transformative impact on the field of complex networks."

Motter is the Harold H. and Virginia Anderson Professor of Physics and Astronomy at Northwestern's Weinberg College of Arts and Sciences.

In a demonstration of its broad applicability, Motter and his colleagues used their framework both to mitigate cascading failures in a power-grid network and to identify potential drug targets in a biochemical signaling network of human cancer.

The findings are published in the journal Nature Communications.

The same connections that provide functionality in networks also can serve as conduits for the propagation of failures and instabilities, Motter said. The emergence of global air transportation and computer networks, for example, brings obvious benefits but at the price of facilitating the spread of diseases and malware.

Furthermore, ecological networks are increasingly affected by perturbations stemming from human actions, and a growing number of human diseases are being linked to malfunction of cellular and molecular networks.

Networks defy human control, however, even in the simplest cases, not only because complex networks consist of a large number of complicatedly connected parts but mainly because they respond nonlinearly（非线性） to disturbances: A small disturbance can create a disproportionately large problem.