  We calculate the cross sections for neutrino interactions with (isoscalar)
nuclear targets in the energy domain all the way up to 10^12 GeV. Small x QCD
effects are included by using a unified BFKL/DGLAP formalism which embodies
non-leading log(1/x) contributions. The few free parameters which specify the
input parton distributions are determined by fitting to HERA deep inelastic
data. The attenuation of neutrinos transversing the Earth at different nadir
angles is calculated for a variety of energy spectra for neutrinos originating
from different sources (from Active Galactic Nuclei, Gamma ray bursts, top-down
models), as well as for atmospheric neutrinos. For this purpose we solve the
transport equation which includes regeneration due to neutral current neutrino
interactions, besides attenuation.
