Does jquery animations rely on a global frame-rate mechanism

Does jquery animations rely on a global frame-rate mechanism

Hello,
I immensely enjoy jquery but I always have troubles when designing complex animation scenarios that include several elements with precise timing.

I wander does jquery use 1 global frame-rate (as flash) and calls 1 step of each active animation when enters a frame or it uses per-animation frame-rate which is not synchronised with the other animations ?