Need a gift for the chronically daydreaming research scientist in your life? Me neither, but apparently knockout rats are ideal. Up until yesterday, I had never heard of a knockout rat, although the name is reminiscent of both fainting goats and a litter of narcoleptic puppies I once saw in a documentary. There is an ad for knockout rats on the back of Science magazine, you see, and that was the last thing I saw before falling asleep last night, so all day today I’ve had the phrase ‘knockout rats’ kicking around my brain pan. Knockout rats, knockout rats… It…