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Roughness (a) and thickness (b) of the growing layer for different front lengths (tube widths) L = 160 (red), L = 320 (green), L = 640 (blue) and L = 1280 μm (purple). (a) Roughness ρ increases with both the nutrient uptake rate k and the length L of the front. (b) Thickness h decreases as k increases; h does not depend on L. (c) Roughness versus thickness; different points correspond to different k from panels (a,b). (Online version in colour.)
