('US') She shifted 'into' low/high 'gear'. = ('Brit') She changed 'into' bottom/top 'gear'. [=she changed to a gear that allows for a slower/faster rate of speed]
This discovery will bring about a 'paradigm shift' in our understanding of evolution. [=will cause people to understand evolution in a completely new way]
We need to 'shift ourselves' [='get moving'] if we're going to make it home before dark.
(..) Why don't we meet? Let me buy you an ice cream. I'm getting on a plane unless you put Queenan on. Queenan had a funeral to go to. This is my shift. Calm down. Why shouldn't I get on a fucking plane, huh? Meet up? You actually want me dead? Look, there is a rat in your unit. (..)2006 The Departed