  We discuss the cosmological amplification of tensor perturbations in a simple
example of brane-world scenario, in which massless gravitons are localized on a
higher-dimensional Kasner-like brane embedded in a bulk AdS background.
Particular attention is paid to the canonical normalization of the quadratic
action describing the massless and massive vacuum quantum fluctuations, and to
the exact mass-dependence of the amplitude of massive fluctuations on the
brane. The perturbation equations can be separated. In contrast to de Sitter
models of brane inflation, we find no mass gap in the spectrum and no
enhancement for massless modes at high curvature. The massive modes can be
amplified, with mass-dependent amplitudes, even during inflation and in the
absence of any mode-mixing effect.
