  Cross section ratios for deep-inelastic scattering from 14N and 3He with
respect to 2H have been measured by the HERMES experiment at DESY using a 27.5
GeV positron beam. The data cover a range in the Bjorken scaling variable x
between 0.013 and 0.65, while the negative squared four-momentum transfer Q^2
varies from 0.5 to 15 GeV^2. The data are compared to measurements performed by
NMC, E665, and SLAC on 4He and 12C, and are found to be different for x < 0.06
and Q^2 < 1.5 GeV^2. The observed difference is attributed to an A-dependence
of the ratio R = sigma_L / sigma_T of longitudinal to transverse deep-inelastic
scattering cross sections at low x and low Q^2.
