  Type 0A string theory in the (2,4k) superconformal minimal model backgrounds,
with background ZZ D-branes or R-R fluxes can be formulated non-perturbatively.
The branes and fluxes have a description as threshold bound states in an
associated one-dimensional quantum mechanics which has a supersymmetric
structure, familiar from studies of the generalized KdV system. The relevant
bound state wavefunctions in this problem have unusual asymptotics (they are
not normalizable in general, and break supersymmetry) which are consistent with
the underlying description in terms of open and closed string sectors. The
overall organization of the physics is very pleasing: The physics of the closed
strings in the background of branes or fluxes is captured by the generalized
KdV system and non-perturbative string equations obtained by reduction of that
system (the hierarchy of equations found by Dalley, Johnson, Morris and
Watterstam). Meanwhile, the bound states wavefunctions, which describe the
physics of the ZZ D-brane (or flux) background in interaction with probe FZZT
D-branes, are captured by the generalized mKdV system, and non-perturbative
string equations obtained by reduction of that system (the Painleve II hierachy
found by Periwal and Shevitz in this context).
