Risk of norovirus transmission during air travel.

Background: During October 2006, an outbreak of norovirus gastroenteritis sickened 200 (59%) of the 379 passengers and 26 (18%) of the 144 crew members on a riverboat. In November 2006, CDC was notified that a group of ill passengers had boarded a commercial flight from St Louis, Missouri, to Atlanta, Georgia. A recent study demonstrated probable norovirus transmission from eight symptomatic flight attendants to passengers on board an aircraft during an international flight; however, there are no published reports of transmission of norovirus on flights of short duration.

Cancelling of pursuit and saccadic eye movements in humans and monkeys.

The countermanding paradigm provides a useful tool for examining the mechanisms responsible for cancelling eye movements. The key feature of this paradigm is that, on a minority of trials, a stop signal is introduced some time after the appearance of the target, indicating that the subject should cancel the incipient eye movement. If the delay in giving the stop signal is too long, subjects fail to cancel the eye movement to the target stimulus.