  In this article the neutrino-pair production from nucleon-nucleon (NN)
bremsstrahlung is explored via medium-modifications of the strong interactions
at the level of the one-pion exchange approximation. It governs the bulk part
of the NN interaction at low densities relevant for the neutrino physics in
core-collapse supernova studies. The resulting medium modified one-pion
exchange rate for the neutrino-pair processes is implemented in simulations of
core collapse supernovae in order to study the impact on the neutrino signal
emitted from the deleptonization of the nascent proto-neutron star.
Consequences for the nucleosynthesis of heavy elements of the material ejected
from the PNS surface are discussed.
