σ =   t  ∇ F +  ( E ) × C × ∇ F +  ( E )    ln ⁡ ( 10 ) F +  ( E )         ( 12  )    MathType@MTEF@5@5@+=feaafiart1ev1aaatCvAUfKttLearuWrP9MDH5MBPbIqV92AaeXatLxBI9gBaebbnrfifHhDYfgasaacH8akY=wiFfYdH8Gipec8Eeeu0xXdbba9frFj0=OqFfea0dXdd9vqai=hGuQ8kuc9pgc9s8qqaq=dirpe0xb9q8qiLsFr0=vr0=vr0dc8meaabaqaciaacaGaaeqabaqabeGadaaakeaaiiGacqWFdpWCcqGH9aqpdaWcaaqaamaakaaabaGaeeiiaaYaaWbaaSqabeaacqWG0baDaaGccqGHhis0cqWGgbGrdaahaaWcbeqaaiabgUcaRaaakiabcIcaOGqabiab+veafjabcMcaPiabgEna0kab+neadjabgEna0kabgEGirlabdAeagnaaCaaaleqabaGaey4kaScaaOGaeiikaGIae4xrauKaeiykaKcaleqaaaGcbaGagiiBaWMaeiOBa4MaeiikaGIaeGymaeJaeGimaaJaeiykaKIaemOray0aaWbaaSqabeaacqGHRaWkaaGccqGGOaakcqGFfbqrcqGGPaqkaaGaaCzcaiaaxMaadaqadaqaaiabigdaXiabikdaYaGaayjkaiaawMcaaaaa@543D@