Out of America: The growing pressure on space could force Washington to end its ban on tower blocks

As my esteemed colleague Jerome Taylor reported for this newspaper yesterday, the fastest-growing website that campaigns for social change is coming to Britain. Change.org has helped a 22 year-old nanny juggling two jobs take on Bank of America, forced the Motion Picture Association to adjust a film's rating and, most thrilling of all, helped bring the appalling tale of Trayvon Martin to public attention. When the parents of that murdered 17-year-old couldn't interest anybody in their son's death, they went to Change.org and garnered 2.2 million signatures instead. That's for one petition. The site launches 15,000 every month.

The most thrilling carnival of democracy in Britain takes place in the capital tomorrow night. London Citizens, the largest alliance of community groups in the country, are hosting their mayoral hustings in Methodist Central Hall. Anyone anywhere who thinks our democracy or civic activism are having a bad time of it should read reports of the evening, or better still, watch the video and then re-evaluate.

George Cowan, who died on 20 April aged 92, was a chemist who influenced everything from the Manhattan Project and the hunt for evidence of the Soviet Union's first nuclear tests to the Santa Fe Opera. After graduate studies at Princeton, Cowan continued his nuclear research as part of the Manhattan Project that developed the atomic bomb. Cowan was a troubleshooter for the effort at various research sites around the country and was among the few people who had knowledge of the bomb's separate components.

Labour peer Lord Ahmed has been suspended by the party while it investigates reports that he offered a £10m "bounty" for the capture of US President Barack Obama.

A dozen US Secret Service agents sent to Colombia to provide security for President Barack Obama at an international summit have been relieved of duty over alleged misconduct.

US President Barack Obama has published his tax return, showing his income fell last year.

President Barack Obama is using privileged access to the White House to reward his most generous financial supporters.

Diary: The US Visit

Diary: The US visit

President Barack Obama offered a warm Oval Office welcome to Chinese Vice President, Xi Jinping, who is widely seen as the next leader of his country, but warned that as it grows in stature China must recognise it has increased responsibilities to the rest of the world.

David Cameron and Barack Obama will hold face-to-face talks on Afghanistan and the global economic crisis when the Prime Minister makes an official visit to the White House next month.

Tehran threatens to close Straits of Hormuz if US enforces an embargo

The New York Post raised the spectre of a woman making a covert bid for power