Tubular Branes in Fluxbranes

We describe the construction of new configurations of self-gravitating p-branes with worldvolume geometries of the form R^{1,p-s} x S^s, with 1\geq s\geq p, ie, tubular branes. Since such branes are typically unstable against collapse of the sphere, they must be held in equilibrium by a fluxbrane. We present solutions for string loops with non-singular horizons, as well as M5-branes intersecting over such loops. We also construct tubular branes which carry in their worldvolume a dissolved, lower dimensional brane (as in the dielectric effect), or an F-string. However, the connection between our solutions and related configurations that have been studied earlier in the absence of brane self-gravity, is unclear. It is argued that, at least in some instances, the self-gravitating solutions do not appear to be able to reproduce stable configurations of tubular branes