Absence of positive solutions to the system of differential inequalities on manifolds

We investigate the nonexistence of positive solutions to a certain system of differential inequalities on a complete connected non-compact Riemannian manifold. We show that if for some reference point x0, the volume of geodesic ball μ(B(x0, r)) ≤ Crp ln q r holds for all large enough r and for some constant C, then there exists no positive solution to the system. Here the exponents p and q are sharp and cannot be relaxed.