"These findings suggest that R&D has become more effective at finding productivity-enhancing ideas, but these ideas may also render rivals’ technologies obsolete, making innovations more transient. Because of obsolescence, rising R&D does not necessarily mean rising aggregate productivity growth."

I Don't Unserstand that. Innovative should increase productivity. If i deploy a new technology i should see productivity gains. Does that Not mean we see should se productivity gains regardless of how fast a technology becomes obsolete? Maybe technologies do not get adopted that fast or the productivity gains do not justify the Investment?