Hi, I was wondering what the difference is between the different EM restraints.  The doc says EnvelopeFitRestraint may be faster for low-res maps but that's about it.  The only place I could find using it is the pde6 exampe.  I tried using it in the tutorial example instead of the GaussianEMRestraint but couldn't get it to work.  I guess I don't really understand what kind of particles are expected in

IMP.em.EnvelopeFitRestraint(particles, map, 11.0, 5.0)

Would this restraint work with the ReplicaExchange anyway?