Symmetry and nonexistence of positive solutions for fractional systems

We consider the following fractional Henonsystem \begin{document}$\left\{ \begin{array}{*{35}{l}} {}&{{(-\vartriangle )}^{\alpha /2}}u = |x{{|}^{a}}{{v}^{p}},~~x'>for \begin{document}$0 and \begin{document}$a, b$\end{document} \begin{document}$≥0$\end{document} , \begin{document}$n≥2$\end{document} . Under rather weaker assumptions, by using a direct method of moving planes, we prove the nonexistence and symmetry of positive solutions in the subcritical case where \begin{document}$1 and \begin{document}$1 .