## Problem 122 — rank:231

**Title:** Morphogen scaling

**Added binding assumptions (LaTeX):**

```latex
Because $c$ is a concentration per physical tissue volume or length, growth requires the conservative transport term $\partial_x(vc)$, unless dilution is explicitly included in the reaction term under a different coordinate convention. Specify the regulator dynamics, source-flux boundary conditions and initial state. Define the stage of boundary measurement and a unique threshold crossing; no crossing or multiple crossings are explicit failure outcomes, not silently chosen favorable boundaries.
```

**Direct edits:** 1. **Fresh external checks:** None; supplied sources retained as provenance.