Geometry of Cyclic Quotients, I: Knotted Totally Geodesic Submanifolds   in Positively Curved Spheres
  We prove that there exists a metric of positive curvature in a three-sphere which admits a given torus knot as a closed geodesic.We also sketch a construction of a metric in a four sphere, very likely of positive curvature, which admits a totally geodesic projective plane with Euler number four. Surpisingly, the technique borrows a lot from the Mostow-Siu-Gromov-Thurston constuction of exotic negatively curved manifolds. 
Alexander Reznikov