Abstract Randomness on full shift spaces q

We give various characterizations for algorithmically random con®gurations on full shift spaces, based on randomness tests. We show that all nonsurjective cellular automata destroy randomness and surjective cellular automata preserve randomness. Furthermore all one-dimensional cellular automata preserve nonrandomness. The last three assertions are also true if one replaces randomness by richness ± a form of pseudorandomness, which is compatible with computability. The last assertion is true even for an arbitrar

A highly virulent variant of HIV-1 circulating in the Netherlands

We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log10 increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV-CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences-is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence