Hölder estimates up to the singular time for the Córdoba-Córdoba-Fontelos equation

We prove that the solution to the Córdoba-Córdoba-Fontelos equation $θ_t-uθ_x=0$, $u=Hθ$, on the real line with analytic initial datum $θ_0(x)=(1+x^2)^{-1}$ develops a finite-time singularity while remaining uniformly bounded in $C^{2/5}$. We also prove that, as the solution approaches the singular