\lim\limits_{r\rightarrow 0}G_{i}(r)\sim \frac{q_{i}}{2\pi r}%\int\limits_{-\infty }^{\infty }d\theta \frac{1}{1+\exp [\varepsilon_{i}(\theta ,r,0)]}\left. \frac{d\varepsilon _{i}(\theta ,r,\mu _{i}/2)}{%d\mu _{i}}\right\vert _{\mu _{i}=0}\frac{d\epsilon (\theta )\,}{d\theta }\,.\dolphin\wolf \goat