Aposematic passion-vine butterflies from the genus Heliconius form communal roosts on a nightly basis. This behaviour has been hypothesized to be beneficial in terms of information sharing and/or anti-predator defence. To better understand the adaptive value of communal roosting, we tested these two hypotheses in field studies. The information-sharing hypothesis was addressed by examining follo...

Recently there has been a surge in interest on how HIV/AIDS affects fertility in countries hit by the disease. In this study, the effect of communal HIV/AIDS on fertility in rural Malawi is estimated using individual data from the 2004 Malawi Demographic and Health Survey on fertility and the ideal number of children. The survey includes individual HIV status, making it possible to distinguish ...

Directed containers make explicit the additional structure of those containers whose set functor interpretation carries a comonad structure. The data and laws of a directed container resemble those of a monoid, while the data and laws of a directed container morphism those of a monoid morphism in the reverse direction. With some reorganization, a directed container is the same as a small catego...