Some helicities in electromagnetic and gravitational fields
  The paper investigates the influences of the helicity on the gravitational mass density, the field source, the charge continuity equation, and the mass continuity equation etc in the electromagnetic field and gravitational field. By means of the algebra of octonions, the magnetic helicity, the current helicity, the cross helicity, the kinetic helicity, the field energy, the enstrophy, and some new helicity terms can be derived from the octonion definitions of the linear mentum and the force in some field descriptions with different operators. The study claims that the gravitational mass density, the field source, the charge continuity equation, and the mass continuity equation will be impacted by the helicity, the field strength, and the vorticity of the rotational objects and of the spinning charged objects in the gravitational field and the electromagnetic field with their adjoint fields. 
Zi-Hua Weng
physics.gen-ph