Signature-causality reflection in an imperfect fluid with vorticity generated by tetrad Abelian gauge transformations An unbounded generalization of Tomita's observable algebras Bargmann representation of quantum absorption refrigerators Solutions to integrable space-time sfifted nonlocal equations Solutions of the Hamilton equations for time-dependent Hamiltonian systems by means of solvable Lie algebras of symmetries Bidimensional honeycomb materials: a graph model through Dirac operator On the far field patterns for electromagnetic scattering in two dimensions