  Cosmological gamma-ray bursts are probably powered by systems harboring a
rotating black hole. We show that frame-dragging creates baryon-poor outflows
in a differentially rotating gap along an open magnetic flux-tube with
dissipation $P=\Omega_T(\Omega_H-2\Omega_T)A_\phi^2$, where $2\pi A_\phi$
denotes the flux in the open tube, for angular velocities $\Omega_H$ and
$\Omega_T$ of the black hole and the torus, respectively. The output in
photon-pair outflow will be reprocessed in an intervening hypernova progenitor
wind or the ISM.
