Model predicted line integrated intensities ratios over ¹²CO( J =1 → 0) as a function σ and N₀ for a purely LN N-PDF. Top row shows the ratios of ¹³CO(J =1 → 0), HCO⁺ (J =1 → 0), HNC(J =1 → 0) and HCN( J =1 → 0) over ¹²CO(J =1 → 0), from left to right. In this top row dashed lines show ratio isocontours increasing by factors of two. Bottom row shows the ratios of¹²CS( J = 2 → 1), C¹⁸O( J = 1 → 0), SO(J_K = 3₂ → 2₁ ) and N₂H⁺ (J = 1 → 0) over ¹²CO(J = 1 → 0), from left to right. In the bottom row isocontours represent factors of tens.