Wigner’s little groups are the subgroups of the Lorentz group whose transformations leave the momentum of a given particle invariant. They thus define the internal space-time symmetries of relativistic particles. These symmetries take different mathematical forms for massive and for massless particles. However, it is shown possible to construct one unified representation using a graphical descr...

Understanding the allocation of skilled labor across industries is necessary to explain interindustry wage differences and the effect of trade on wages. This paper develops a multisector assignment model with both heterogeneous labor and a non-labor input in which high skill agents match with high input productivity sectors where they can best leverage their talent. When the ranking of sectors ...

A time harmonic far field model for closed electromagnetic time reversal mirrors is proposed. Then, a limit model corresponding to small perfectly conducting scatterers is derived. This asymptotic model is used to prove the selective focusing properties of the time reversal operator. In particular, a mathematical justification of the DORT method (Decomposition of the Time Reversal Operator meth...