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Control theory can be used to steer engineered and natural systems towards a desired state, but a framework to control complex self-organized systems is lacking. Can such networks be controlled? Albert-László Barabási and colleagues tackle this question and arrive at precise mathematical answers that amount to 'yes, up to a point'. They develop analytical tools to study the controllability of an arbitrary complex directed network using both model and real systems, ranging from regulatory, neural and metabolic pathways in living organisms to food webs, cell-phone movements and social interactions. They identify the minimum set of driver nodes whose time-dependent control can guide the system's entire dynamics. Surprisingly, these are not usually located at the network hubs. On the cover, part of the cactus structure, a subset of nodes that have a key role in the control of real networks, with nodes in blue and drivers in red, visualized by Mauro Martino ( go.nature.com/wd9Ek2).
Vesuvius is one of the most dangerous volcanoes in the world — but scientists and the civil authorities can't agree on how to prepare for a future eruption.
The World Health Organization needs major reform to regain its leadership as a convener and provider of scientific and technical knowledge, says Barry R. Bloom.
Two months on from the earthquake and tsunami that hit their country on 11 March, five Japanese seismologists reflect on what they have learned from it so far.
One might expect that social networks would generally be harder to control than naturally occurring systems such as biological networks. But this is not so, according to a new study. See Article p.167
Mutations that lead to increased activity of the Notch signalling pathway are well defined in human cancer. New work implicates decreased activity of this pathway in a type of blood cancer. See Letter p.230
Some of the strangest galaxies in the Universe just got stranger. It seems that many galaxies in the early Universe not only packed a huge number of stars into a very small volume, but were also rotating rapidly.
Lipids of the N-acylethanolamine family mediate cell signalling across a wide range of organisms. In nematode worms, they translate food availability into fundamental choices about development that affect lifespan. See Letter p.226
There were probably many reasons for the adoption of agriculture by prehistoric human societies. A fresh perspective comes from a quantitative estimate of the relative productivity of farming and foraging.
Some complex problems in physics can be recast as finding the ground state of an interacting quantum system. Not getting excited along the way can be the challenging part. See Letter p.194