Gravitational Scattering in the c = 1 Matrix Model
  The $c=1$ matrix model is equivalent to $1+1$ dimensional string theory. However, the tachyon self-interaction in the former is local, while in the latter it is nonlocal due to the gravitational, dilaton and higher string fields. By studying scattering of classical pulses we show that the appropriate nonlocal field redefinition converts the local matrix model interaction into the expected string form. In particular, we see how the asymptotic behavior of the gravitational field appears in the scattering. 
Makoto Natsuume and Joseph Polchinski