Figure 2: Left panel shows the four partial mass contribution to in (12) as function of the lightest mass for allowed intervals in the case of 3+1 mixing with Inverted Ordering. Right pannel shows the allowed ranges in - parameter space, both in the standard three-neutrino picture (unfilled band space) and with one sterile neutrino (filled band space) for the 3+1 case as defined by (14).