  The tilt modulus of a defective Abrikosov vortex lattice pinned by material
line defects is computed using the boson analogy. It tends to infinity at long
wavelength, which yields a Bose glass state that is robust to the addition of
weak point-pinning centers, and which implies a restoring force per vortex line
for rigid translations about mechanical equilibrium that is independent of
magnetic field. It also indicates that the Bose glass state breaks into pieces
along the direction of the correlated pinning centers if the latter have finite
length. The critical current is predicted to crossover from two dimensional to
three dimensional behavior as a function of sample thickness along the
correlated pinning centers in such case. That crossover notably can occur at a
film thickness that is much larger than that expected from point pins of
comparable strength. The above is compared to the dependence on thickness shown
by the critical current in certain films of high-temperature superconductors
currently being developed for wire technology.
