Hydra groups

We give examples of CAT(0), biautomatic, free-by-cyclic, one-relator groups which have finite-rank free subgroups of huge (Ackermannian) distortion. This leads to elementary examples of groups whose Dehn functions are similarly extravagant. This behaviour originates in manifestations of Hercules-versus-the-hydra battles in string-rewriting.Comment: 26 pages, 3 figure

Self-initiated (re)education of digital technology in retired content creators

The retired population in the United Kingdom is rising and statistics show that growth in the use of digital technologies and the Internet are also increasing within this age group. Small but substantial proportions are using the Internet for something more than to search and consume online goods and materials. This article explores what and where retired people learn digital technologies, skills often more directly associated with people born into a digital world. Through the use of qualitative data this article provides an insight into the (re)education of retired Internet users who are using digital technology and web media to create and share their own content. Digital technology within this sample of over 65s is often learnt unintentionally as a consequence of adopting a new hobby or interest in retirement or the rediscovery of an old one that they may not have been able to explore prior to retirement

Ethnohistoric Records of Hunter-Gatherer Diet of the Texas/Mexico Borderlands: Implications for Staple Foods of the Lower Pecos Canyonlands During the Holocene

Hinds Cave (41VV456) and other rockshelters excavated in the Lower Pecos Canyonlands have yielded thousands of coprolites spanning the Holocene. To date, several hundred specimens have been analyzed, providing a detailed record of meals consumed by hunter-gatherers who called this landscape home. This article compares the paleodietary records derived from these specimens with the foodways documented in the ethnohistoric records available for the Lower Pecos Canyonlands and adjacent landscapes. This comparison confirms the deep temporal roots of the foodways recorded in the earliest written records of the Texas/Mexico borderlands. Coprolite data corroborate the strong dependence on the seasonal staples of lechuguilla (Agave lechuguilla), nopales (Opuntia sp.), and tunas (Opuntia sp.) observed in the ethnohistoric literature. The temporal endurance of this subsistence strategy suggests that there may be some components of this dietary pattern that could inform on many of the diet-related health issues observed among modern Native American and other populations