Finite-time blow-up of solutions of an aggregation equation in Rn

We consider the aggregation equation u(t) + del (.) (u del K * u) = 0 in R-n, n >= 2, where K is a rotationally symmetric, nonnegative decaying kernel with a Lipschitz point at the origin, e.g. K(x) = e(-vertical bar x vertical bar). We prove finite-time blow-up of solutions from specific smooth initial data, for which the problem is known to have short time existence of smooth solutions.