How does the sale 10 yr treasury Bond affect interest rates?

J.P. asked: I know when Yields go down, rates go down. What I dont understand is if the fed is buying 11b in 10 yr treasuries wouldnt that make yeild go up forcing rates up?

Fed buying 10-year treasuries and more mortgage-securities; how low will rates go?

lguz asked: Anyone want to guess how low mortgage rates will go? The Fed just announced plans to buy $300 bln worth of treasury bonds, and $750 bln of mortgage backed securities. Both moves will affect rates.
Estimates?