Abstract: A Magnetic Particle Imaging (MPI) system with a magnet configured to generate a magnetic field having a field free line, the system including at least one shim magnet configured to modify the magnetic field in a manner to maintain desired magnetic flux distributions during imaging.

Abstract: A lower extremity exoskeleton includes: at least one power unit; two leg supports designed to rest on the ground; two knee joints configured to allow flexion and extension between respective shank and thigh links of the leg supports; an exoskeleton trunk rotatably connectable to the leg supports; and two hip actuators configured to create torques between the exoskeleton trunk and the leg supports. In use, the hip actuators create a torque to move the leg supports backward relative to the exoskeleton trunk during a stance phase, which pushes the exoskeleton trunk forward. A second torque may be used to move the leg supports forward relative to the exoskeleton trunk into a swing phase. Additionally, a swing torque may be generated during the swing phase to move the leg support forward relative to the exoskeleton trunk. This results in decreased oxygen consumption and heart rate of a user wearing the exoskeleton.