**Author details**

A.J.S. Machado, S.T. Renosto, C.A.M. dos Santos and L.M.S. Alves *Escola de Engenharia de Lorena, Universidade de São Paulo, Lorena, SP, Brazil* 

Z. Fisk

*Departments of Physics and Astronomy, University of California at Irvine, Irvine, USA* 
