Adaptation: dm/dt = (C−m)/τ
Tumble rate: λ = λ₀·f(m−C)
Gradient sensing: dC/dt > 0 → ↓λ
Run = straight swim.
Tumble = random new θ.
Temporal comparison of C: ΔC = C(t)−m(t)
More attractant → fewer tumbles → biased drift up-gradient.