51.   Researchers have known that there must be brain cells, or neurons, that turn on only at the onset of sleep.

52.   Researchers knew Blackbeard had time to relieve the ship of valuables.

53.   Researchers know that the three biggest health problems facing men and women are heart disease, cancer and strokes.

54.   Researchers now know this view is wrong.

55.   Researchers do not know if the firefighters are being hurt by the heat or by certain types of fires.

56.   Researchers have known for years that a major disincentive in the willingness of poor fathers to pay child support is where their money goes.

57.   Researchers have long known that the energy associated with various types of radiation can split apart proteins.

58.   Researchers knew how to make a more powerful chip years ago.

59.   Researchers know little about why some people respond fully to anti-depressant treatment and others do not.

60.   Researchers know of small animals, like the cotton rat and pygmy mouse, which instinctively manage to avoid fire ants when giving birth.