A Pinching constant for harmonic manifolds
  In this note we shall show that the sectional curvature of a harmonic manifold is bounded on both sides. In fact we shall give a pinching constant for all harmonic manifolds. We shall use the imbedding theorem for harmonic manifolds proved by Z.I.Szabo and the description of screw lines in hilbert spaces to prove the result. 
K. Ramachandran and Akhil Ranjan (Dept of Mathematics, Indian   Institute of Technology, Mumbai, India)