There has been increasing friction between the two sides since an internal airport business review was leaked to the union in October 2001.

BBC: Strikes loom at Manchester Airport

His thesis is that Europe's increasing friction with the U.S. is a natural outgrowth of the second-fiddle role the continent is destined to play in world affairs.

FORBES: Sidelines

Lead scientist Professor Nicholas Spencer suspected that this property could neutralise the effectiveness of the synovial fluid as a lubricant - increasing friction and wear in the hip implant.

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What is suggested to be at work here is the concept of asperities - the idea that if you take two rough surfaces and rub them together, the peaks in one will couple with the troughs in the other, increasing friction.

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