  Using first-principle simulations for the probability density of finding a
3He atom in the vicinity of the screw dislocation in solid 4He, we determine
the binding energy to the dislocation nucleus E_B = 0.8 \pm 0.1 K and the
density of localized states at larger distances. The specific heat due to 3He
features a peak similar to the one observed in recent experiments, and our
model can also account for the observed increase in shear modulus at low
temperature. We further discuss the role of 3He in the picture of superfluid
defects.
