(color online) Compensated Nu/Ra^0.3 as a function of Ra. Here all results are obtained by DNS. The 3D results from Stevens et al.^[8] (Γ = 1/2) are indicated by the orange hollow circles and the present quasi-2D results are indicated by blue solid circles. Analogously, the 2D results from this work and Zhang et al.^[18] are indicated by red solid triangles and green hollow triangles, respectively. The GL theory with updated pre-factors^[4] is indicated by the black solid line. The dash line represents the best power-law fit of present 2D results.