This makes it straightforward to predict when the cycle will swing from downturn to upturn.

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And so it goes, cycle after cycle, as conditions swing back and forth from one extreme to the other.

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But for the rest, the recovery in manufacturing and housing in swing states owes more to the rhythms of the business cycle and global conditions, or to broad-based federal stimulus and easy monetary policy.

ECONOMIST: The economy

Its earnings typically swing in response to occasional catastrophes like hurricanes and earthquakes, or by the profit cycle (currently at low ebb) in the competitive auto insurance sector.

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Warren White of the Scripps Institution of Oceanography in La Jolla, California, and his colleagues were the first to find that sea-surface temperatures across the globe swing up and down in a 10-to 12-year period that lags behind the solar cycle by two to three years.

ECONOMIST: The earth��s climate