3    dimension

-1.0 -1.0 -1.0   x_low
 1.0  1.0  1.0   x_high
 40   40   40    Number of cells at coarsest level
  2    2   2     Width of ghost cell layers
  2    2   2     Refinement ratio
  3              Maximum number of levels
  0.8           Target efficiency for regridding
