Reply to [arXiv:1105.5147] "Are GRB 090423 and Similar Bursts due to   Superconducting Cosmic Strings?"
  The GRB outflow driven by superconducting cosmic strings is likely to be an arc rather than a usually-considered spherical cap. In such a case, the afterglows of the cosmic string GRBs could be basically consistent with the observation of the high-redshift GRBs. 
K. S. Cheng, Yun-Wei Yu, and T. Harko
astro-ph.HE gr-qc hep-ph