Sharif Digital Repository

In this thesis, we study a rigidity problem for a 2-step nilmanifold such as Γ by some information about its geodesic flows, where is a simply connected 2-step nilpotent Lie group with a left invariant metric, and Γ is a discrete cocompact subgroup of . For the solution to this problem, first, we consider an algebraic aspect of it; since isometry groups of simply connected Riemannian manifolds can be characterized in a purely algebraic way, i.e., normalizers. Also, as we will show, proper and smooth actions of Lie groups and closed subgroups of isometries for smooth Riemannian structures can be regarded as the same topic. Then, in a generalized setting, when passing from the case of... 

Investigating the influence of shoes on variables of human biomechanics is of a high importance. The purpose of this study was to examine the effect of auxetic Nike Free RN shoe on kinematics and kinetics of human body. It was asked from 11 healthy male to perform drop vertical jump in three conditions: with auxetic Nike Free RN, with conventional shoe and barefoot. 3D Cartesian positions of the markers, which were stuck to the subjects’ bodies, were recoeded using Vicon camera system. Ground reaction force and its center of pressure of each foot captured using two force plates. Moreover, activation of rectus abdominis, longissimus, iliocostalis lomburom and multifidus were recorded using...