From Ars Technica: In biology, researchers are usually pretty dismissive of experiments that result in only a single sample. When there’s (as scientists put it) an “n of one,” it’s hard to tell whether the results are significant or a random fluke. But, in the case of a paper released on Monday by PNAS, the n happens to be a cow that carries a transgenic construct that knocks down the expression of a gene that encodes one of the major allergens found in milk. And the data that led to the cow makes a compelling case that the development is significant.