olectric conductivity in the presence of helical currents are studied for the ... plint)+(int)2 = (ext)*/8m. .. .. .. (10). We assume a vacuum outside the cylinder. ... h+2n(2n+ 4)c 6(2nâ 2)(2n+4) - k d(2n+2)(21+4)* d(2n+2)(2n+4) we have dan+? aan.