Neuropathologic studies can classify Aβ, tau and other co-existing pathologies, but it is not yet possible to determine with certainty the age at which Aβ deposition began in an individual patient.
Ireland can offer companies a unique level of certainty over the rate at which their profits will be taxed for years to come, the taoiseach has claimed.
"I'm drawn to it," he explains, "because it's the moment at which the medieval certainties that had endured for centuries were turned upside down.
"We are at a turning point at which we can say, with certainty, that we are leaving the recession behind us," the national economy minister, Giorgos Stathakis, said last week.
One of the biggest challenges for doctors and their patients is making decisions without complete certainty, so they must work together to determine the point at which the risk of further testing ceases to be acceptable.
A. afarensis disappears at around three million years ago, but the eastern African fossil record is poor following that time, so the precise date at which the species goes extinct is not known with certainty.
These include: the speed at which learning happens, the simplicity or complexity of knowledge, the certainty with which things are known, and whether an individual's learning ability is innate or can be improved through effort.
At which point, enter football's great dunderheaded experiment with the idea that certainty can be introduced to a game of marginal calls.
It is thus not possible to conclude with certainty whether ISR similar to those observed with H. pylori occur in other species, and at which frequency.
