To follow up on your previous experiment with DNA replication in virus U238, conduct another Meselson-Stahl type experiment, again allowing a virus to replicate in the presence of "heavy" nitrogen until both strands of its genome are "heavy." In this experiment, you allow virus U238 to undergo two complete rounds of replication in the presence of "light" nitrogen. What ratio of "heavy" to "light" viral DNA would you expect to find at the end of two complete rounds of replication?