And most figures even of foreigners are by-products of data gathered, by separate agencies, for other reasons, not to measure the flow or stock of migrants.

ECONOMIST: Migration statistics

"You flow gas from the samples through fairly long tubes that are specifically designed to separate out the different constituents of the gas, " Vasavada said.

MSN: New Mars rover hunts for life by 'cooking' rocks

Hairballs mean more inventory costs because at each geographically separate production stage a buffer stock of unfinished items is kept to cope with any disruptions in the flow from another plant.

WSJ: 3M Begins Untangling Its 'Hairballs'