affiliation not provided to SSRN, Shaanxi Normal University, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, Northwestern Polytechnic University (NPU), Northwestern Polytechnic University (NPU), Northwestern Polytechnic University (NPU), Northwestern Polytechnic University (NPU), University of Georgia, University of Georgia, University of Georgia, University of Georgia, Northwestern Polytechnic University (NPU), Northwestern Polytechnic University (NPU), Northwestern Polytechnic University (NPU), Northwestern Polytechnic University (NPU), Shaanxi Normal University, University of Georgia and Shaanxi Normal University