Optimal mass transport on Alexandrov spaces and Ricci curvature

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We prove that given an Alexandrov space and a positive Radon measure on it, if the measure satisfies a comparison condition of Bishop-Gromov type and if the space contains a straight line, then the space is homeomorphic to the direct product of some space and the real line. This is a generalization of the Cheeger-Gromall splitting theorem.As another result, given a sequence of closed Riemannian manifolds of nonnegative Ricci curvature and with a uniform upper bound of diameter, if the k-th eigenvalue of the Laplacian of the manifold in the sequence is divergent to infinity, then the first eigenvalue is also divergent and the measure concentration happens.