anger, as our correspondent, orla guerin reports from the capital algiers. new tension on the streets of algiers. a change in the air, after weeks of peaceful mass protests. young revolutionaries facing down the police who tried to ban this demonstration. but the protesters gathered anyway. they won't be swept away easily. the landscape has changed here. what mis missing is fear. well, the security presence has been building here. in the last half an hour or so, we've had tear gas and water cannon being used. the authorities are trying to control what is happening here on the streets, to stop the protests. old habits die hard. but the demonstrators say it's too late for that. algeria's vast young population has found its voice,