  We discuss the interplay between IR and UV divergences in vacuum
configurations with open and unoriented strings. We establish a general
one-to-one correspondence between anomalies and R-R tadpoles associated to
sectors with non-trivial Witten index. The result does not require any
supersymmetry to be preserved by the configuration. Under very mild conditions
of supersymmetry, a similar correspondence is found between NS-NS tadpoles and
RG-flows in gauge theories on D-branes and O-planes. We briefly comment on the
AdS/CFT counterpart of the results.
