We develop a consistent model of a quantum damped harmonic oscillator with arbitrary time-dependent frequency and damping coefficients within the framework of the Heisenberg–Langevin equations with two noncommuting delta-correlated noise operators justifying the choice of the “minimal noise” set of damping coefficients and correlation functions.

This paper gives a qualitative description how Young tableaux can be used to perform a Clebsch-Gordan decomposition of tensor products in SU(3) and how this can be generalized to SU(N).

This essay describes the development of groups used for the specification of symmetries from ordinary and magnetic point groups to Fedorov and magnetic space groups, as well as other varieties of groups useful in the study of symmetric objects. In particular, we consider the problem of some incorrectness in Vol. A of the International Tables for Crystallography. Some results of tensor calculus ...

Bounds of association coefficients for binary variables are derived using the arithmetic-geometric-harmonic mean inequality. More precisely, it is shown which presence/absence coefficients are bounds with respect to each other. Using the new bounds it is investigated whether a coefficient is in general closer to either its upper or its lower bound.