This paper presents a survey of recent successful algorithms for blind separation of determined instantaneous linear mixtures of independent sources such as natural speech or biomedical signals. These algorithms rely either on non-Gaussianity, nonstationarity, spectral diversity, or on a combination of them. Performance of the algorithms will be demonstrated on separation of a linear instantaneous mixture of audio signals (music, speech) and on artifact removal in electroencephalogram (EEG).

RNA viruses replicate as complex and dynamic mutant distributions. They are termed viral quasispecies, in recognition of the fundamental contribution of quasispecies theory in our understanding of error-prone replicative entities. Viral quasispecies have launched a fertile field of transdiciplinary research, both experimental and theoretical. Here we review the origin and some implications of the quasispecies concept, with emphasis on internal interactions...