The harbour's sluices ran until 1971 when the decline in port trade led to them being closed for the last time.

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Some of the Dutch works are permanent dijks, but others are open sluices that merely shut when storms are coming to block surges.

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In the case of Visa and MasterCard (nyse: MA - news - people ), when a credit card is swiped, the transaction gets relayed--via an intermediary--to the credit card company, which then sluices the funds to the merchant's bank account.

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