51.   Now a Russian scientist has found an explanation.

52.   Nuclear authorities Saturday scrambled to find an explanation for a coolant leak that forced a shut-down of an experimental fast-breeder reactor.

53.   Scientists are pondering what reasons lie behind these developments, and it may be years before convincing explanations are found.

54.   Similar small outbreaks have happened throughout the country, but they usually disappear or an explanation is found almost immediately, Spry said.

55.   No medical explanation has been found for the sickness.

56.   Researchers set out to find an explanation of why people who eat a lot of fat are at greater risk of developing colon cancer.