  The problem of a single impurity in one dimensional Tomonaga-Luttinger
liquids with a repulsive electron-electron interaction is discussed. We find
that the renormalization group flow diagram for the parameters characterizing
the impurity is rather complex. Apart from the fixed points corresponding to
two weakly connected semi-infinite wires, the flow diagram contains additional
fixed points which control the low temperature physics when the bare potential
of the impurity is not strong.
