  We measure the position- and momentum- space breathing dynamics of trapped
one-dimensional Bose gases. The profile in real space reveals sinusoidal width
oscillations whose frequency varies continuously through the quasicondensate to
ideal Bose gas crossover. A comparison with theoretical models taking into
account the effect of finite temperature is provided. In momentum space, we
report the first observation of a frequency doubling in the quasicondensate
regime, corresponding to a self-reflection mechanism. The disappearance of this
mechanism through the quasicondensation crossover is mapped out.
