  We find a combinatorial setting for the coefficients of the Boros-Moll
polynomials $P_m(a)$ in terms of partially 2-colored permutations. Using this
model, we give a combinatorial proof of a recurrence relation on the
coefficients of $P_m(a)$. This approach enables us to give a combinatorial
interpretation of the log-concavity of $P_m(a)$ which was conjectured by Moll
and confirmed by Kauers and Paule.
