The inverse scattering transform for the KdV equation with step-like   singular Miura initial profiles
  We develop the inverse scattering transform for the KdV equation with real singular initial data $q(x)$ of the form $q(x) = r'(x) + r(x)^2$, where $r\in L^2_{\textrm{loc}}$ and $r=0$ on $\mathbb R_+$. As a consequence we show that the solution $q(x,t)$ is a meromorphic function with no real poles for any $t>0$. 
Sergei Grudsky, Christian Remling, and Alexei Rybkin
math.SP