Cross capacitance and inductance

$$E=C^{mn}V_m V_n$$ $$E=L^{mn}I_m I_n$$ Usually $$C^{xy}, L^{xy}=0$$

Anti-periodic potentials and Bloch theorem

 $$V(x+a)=-V(x)$$

$$|\psi(x+a)|^2=-|\psi(x)|^2+1?$$

Viscosity in a Plasma

 $$\boldsymbol{\tau}=\mu(\nabla\textbf{A}+\nabla\textbf{A}^T)$$ where \(\textbf{A}\) is the magnetic vector potential.