In a population of constant size, whose family sizes evolve as Wright-Fisher diffusions, all individuals alive at time t have a most recent common ancestor (MRCA) who lived at time A(t), say. The process (A(t)) has piecewise constant paths. At each jump time En, a new MRCA takes over, who lived at time Bn := A(En). We construct the random sequence (Bn, En) in terms of a look-down process and in...

Arithmetic coding is a well-known technique for lossless coding or data compression. It is based on splitting a current interval into sub-intervals, each sub-interval corresponding to a possible symbol to be encoded and the size of each sub-interval corresponding to the probability of the associated symbol. This involves multiplying the current interval size A by one or more probabilities, whic...

We describe a numbering scheme for versions with alternatives that has a useful lexicographical ordering. The version hierarchy is a tree. By inspection of the version numbers, we can easily determine whether one version is an ancestor of another. If so, we can determine the version sequence between these two versions. If not, we can determine the most recent common ancestor to these two versio...

Many human cultures engage in the collective commemoration of dead members of their community. Ancestor veneration and other forms of commemoration may help to reduce social distance within groups, thereby encouraging reciprocity and providing a significant survival advantage. Here we present a simulation in which a prototypical form of ancestor commemoration arises spontaneously among computat...

In 1990, an attitude survey was conducted of 402 animal rights activists attending a national march in Washington, DC (S. Pious, 1991). The present article reports the results of a follow-up survey of 372 activists attending a similar event in 1996. A comparison of the 1990 and 1996 surveys suggests that during this time a significant shift took place in the priorities of the animal rights move...

OBJECTIVES To investigate the longitudinal association of nailfold capillary density (NCD; as a potential marker of activity) with various other clinical measures of disease activity and to evaluate baseline NCD as a predictor of disease outcome in children with JDM. METHODS Data from 809 clinic visits from 92 JDM patients were prospectively collected at each clinic visit over a time period o...