  Based on the Isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport
model, the in-medium nucleon-nucleon inelastic scattering ( which is dominated
by pion production at low and intermediate energies) is explored. It is found
that the in-medium modification of nucleon-nucleon inelastic scatterings
appears to reduce the neutron to proton ratio n/p at higher kinetic energies.
Although the in-medium modification of nucleon-nucleon inelastic scatterings,
as expected, affects the value of $\pi^-/\pi^+$ ratio, considering a series of
undetermined properties of delta resonance and $\pi$ in medium, the energetic
neutron to proton ratio n/p is more suitable to be used to probe the in-medium
correction of nucleon-nucleon inelastic scatterings.
