Her lab now focuses on obtaining a mechanistic understanding of biological processes involving RNA. Data obtained with these systems may be used to test and refine mechanistic hypotheses. See for a comparison between mechanistic and correlative models. It does not readily apply in a mechanistic understanding of scientific discovery. For their mechanistic similarity to mammalian prions, they were termed yeast prions. The problem with these theories is that they are so narrowly mechanistic. It is a purely descriptive term that has little or no mechanistic interpretation. Another criticism is that vitalists have failed to rule out mechanistic explanations. These include the (mentioned above) regularity, probabilistic, counterfactual, mechanistic, and manipulationist views. Therefore, the classification was, in essence, based on animal experiments and mechanistic considerations. Older children and adults continue to develop an understanding of mechanistic fragments. It remains unclear how this may work without further mechanistic elements. They followed two traditions, one mechanistic, one vitalistic after Henri Bergson's philosophy of evolution. Menthone was crucial to one of the great mechanistic discoveries in organic chemistry. Disappointed by the constraints of the mechanistic method some Russian Formalists adopted the organic model.