Reuters: The volcanic ash cloud making much of northern Europe a no-fly zone has hurt the prices of airline stocks, paralyzed air cargo delivery and disrupted business and leisure travel. But analysts expect the overall economic impact to be minor, since the disruption appears unlikely to last continuously over a long period. HOW LONG WILL THE DISRUPTION LAST? This depends on how long the volcano under Iceland’s Eyjafjallajokull glacier keeps erupting, whether it continues …