  The 0.7 conductance anomaly in the quantized conductance of trench etched
GaAs quantum point contacts is studied experimentally. The temperature
dependence of the anomaly measured with vanishing source-drain bias reveals the
same activated behavior as reported earlier for top-gated structures. Our main
result is that the zero bias, high temperature 0.7 anomaly found in activation
measurements and the finite bias, low temperature 0.9 anomaly found in
transport spectroscopy have the same origin: a density dependent excitation
gap.
