He said there had been a build-up of pressure, which was relieved when some fluid was removed through a small opening in the skull.

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The salt of the seawater draws the fresh water across the membrane, leading to a build-up of pressure which forces water through the turbine, generating electricity.

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However, an inquest held into his death in February 2011 found that he died after his bowel burst due to a build-up of pressure in it - not because of any problems caused by a surgical instrument.

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Continued pressure requires continued build-up of military forces, but this clearly cannot go on for ever.

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