For GPS, this is an enormous issue because it turns out that the clocks on the satellites drift by almost 40, 000 nanoseconds per day relative to the clocks on the ground because they are high above the earth's surface (and therefore in a weaker gravitational field) and are moving fast relative to the ground.

BBC: Meet the world's director of time

Hispanics have gained considerable ground relative to whites, closing the dropout gap from 21 percentage points to 9.

WSJ: Best of the Web Today: The New Nixon

Thus, a spy plane could not be completely invisible if it were to be used for espionage or, indeed, flown at all, since its pilots would need to know its position relative to the ground.

ECONOMIST: How to weave a cloak that makes you invisible

But if all you do is comment on the relative quality of life in the penthouse and the ground floor without acknowledging the fact that people regularly come and go from both you create a totally erroneous impression of economic inequality.

FORBES: Innumeracy, Statistics And The Art Of Lying

We can't go back to a bubble-and-burst economy based on reckless speculation and spending beyond our means, where a relative few do spectacularly well while the middle class loses ground.

WHITEHOUSE: Town Hall in Los Angeles

Meanwhile, there is a relative calm in Venezuela according to press reports and investment sources on the ground in Caracas.

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What we specialize in at Advisory Research, though relative to energy, is finding very attractive companies with tremendous values of assets in the ground.

FORBES: Scouting the Globe for Small Caps

"The two metres is what we call the relative accuracy, " explained Dr Manfred Zink, the project manager for the TanDEM-X ground segment at DLR.

BBC: Mapping Earth's surface in 3D

Over the long term, higher productivity growth and better-functioning labour markets are vital if economies in southern Europe are to regain the competitive ground they lost in the first decade of monetary union, when their unit labour costs soared relative to those in northern countries like Germany.

ECONOMIST: Free exchange