  Electron densities at the edge site in one-dimensional Hubbard model and t-J
model are studied by using the Bethe ansatz solutions and exact diagonalization
method. It is found that the boundary is electron-attractive, or equivalently
hole-repulsive, near half-filling. We propose a new criterion to determine
whether the carriers in a strongly correlated system are electron-like or
hole-like depending on the electronic behavior at the boundary.
