Squirals and beyond: Substitution tilings with singular continuous   spectrum
  The squiral inflation rule is equivalent to a bijective block substitution rule and leads to an interesting lattice dynamical system under the action of $\mathbb{Z}^{2}$. In particular, its balanced version has purely singular continuous diffraction. The dynamical spectrum is of mixed type, with pure point and singular continuous components. We present a constructive proof that admits a generalisation to bijective block substitutions of trivial height on $\mathbb{Z}^{d}$. 
Michael Baake (Bielefeld) and Uwe Grimm (Milton Keynes)
math.DS math.MG