Bulletin – March 2017 Equation (4)

π e r e = P B MathType@MTEF@5@5@+=feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLnhiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=xfr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSGaaeaacqaHapaCdaWgaaWcbaGaamyzaaqabaaakeaacaWGYbWaaSbaaSqaaiaadwgaaeqaaaaakiabg2da9maaliaabaGaamiuaaqaaiaadkeaaaaaaa@3DAE@