A system may include one, two or more magnetic field systems. The magnetic field system may be configured to provide a magnetic field in a first direction to the tissue. The magnetic field system may include at least one magnetic field source to produce the magnetic field. The magnetic field produced by the at least one magnetic field source may include a magnetic field produced by at least one of a permanent magnet, a temporary magnet or electric current flow through a conductor. The same or a second magnetic field system may be configured to provide a second magnetic field in a second direction to the tissue. The magnetic field system may include two or more sources to provide the magnetic field in a second, third or fourth direction that is non-parallel to the first direction.