The time-dependent projection operator technique according to Willis and Picard (Phys. Rev. A 9 (1974) 1343) offers a unique quantum statistical description of two interacting subsystems. The technique is used here to go beyond the standard quantum master equation (QME) for a small system...

It is well known that non-normality plays an important role in asset and risk management. However, handling a large number of assets has long been a challenge. In this paper, we present a statistical technique that extends Principal Component Analysis to higher moments such as skewness and...