Mr Sadr's 30-strong block of followers in parliament, which has 275 members, was the largest faction in the ruling Shia alliance and had backed Mr Maliki as prime minister largely to stop the post going to the Supreme Council for Islamic Revolution in Iraq (SCIRI), their bitter rivals in the Shia alliance.

ECONOMIST: The prime minister, Nuri al-Maliki, is ever more embattled

As a result Latinos have been less strong as a block than the Irish were after the immigration wave of the 19th century, or than blacks have been recently, he says.

ECONOMIST: Latinos and American politics

When minority shareholders are legally protected, as they are in Sweden, with strong rights to block certain decisions with a minority vote at shareholders' meetings, it becomes more advantageous to have large owners nominate the directors.

FORBES: Leadership

So long as low yields continue to support America's housing bubble and hence strong consumer spending, they will block any significant reduction in the country's current-account deficit.

ECONOMIST: World economy

The government has a very strong case, on conventional economic grounds, to block the merger.

FORBES: AT&T Merger Suit Shows Regulators Getting Agressive On Cellular

When the Real Madrid man was allowed to run at goal he twice met with strong challenges from Lucio, the first of which was a superb block from a shot on the left, but the second, from a similarly aggressive run on the right, inadvertently deflected the ball across goal to Raul Meireles only for the midfielder to shoot wide.

BBC: Portugal 0-0 Brazil

In fact it is almost impossible to block the exit for the highly skilled if the lure is strong enough.

ECONOMIST: Open up | The

"Hon Hai tried to have a strong influence on the way in which Sharp is run, that was a major stumbling block, " said Mr Fasol of Eurotechnology Japan.

BBC: Samsung to buy 3% stake in Japanese rival Sharp

The result, in a mountain range characterised by soft, crumbling rock which desperately needs strong roots to hold it together, has been an increasing number of landslides, which block roads, railways and even rivers.

ECONOMIST: From the archive