  We study the five-orbital Hubbard model including the charge quadrupole
interaction for iron pnictides. Using the fluctuation-exchange (FLEX)
approximation, orbital fluctuations evolve inversely proportional to the
temperature, and therefore the resistivity shows linear or convex T-dependence
for wide range of temperatures. We also analyze the Eliashberg gap equation,
and show that s-wave superconducting state without sign reversal (s++ -wave
state) emerges when the orbital fluctuations dominate over the spin
fluctuations. When both fluctuations are comparable, their competition gives
rise to a nodal s-wave state. The present study offers us a unified explanation
for both the normal and superconducting states.
