Parity Breaking in Nematic Tactoids

We theoretically investigate under what conditions the director field in a spindle-shaped nematic droplet or tactoid obtains a twisted, parity-broken structure. By minimizing the sum of the bulk elastic and surface energies, we show that a twisted director field is stable if the twist and bend elastic constants are small enough compared to the splay elastic constant, but only if the droplet volume is larger than some minimum value. We furthermore show that the transition from an untwisted to a twisted director-field structure is a sharp function of the various control parameters. We predict that suspensions of rigid, rod-like particles cannot support droplets with a parity broken structure, whereas they could possibly occur in those of semi-flexible, worm-like particles.Comment: 20 pages, 9 figures, submitted to Journal of Physics: Condensed Matte

Direct Evidence for the Importance of Small Animals to Prehistoric Diets: A Review of Coprolite Studies

Researchers tend to underestimate or ignore the importance of small animals to the prehistoric diet due to the difficulty of separating cultural from noncultural faunal debris excavated from sites. Human coprolite analyses (dessicated human feces) indicate prehistoric dietary consumption of small animals. The large number of coprolites analyzed from North America reveals direct ingestion of small animals and indicates that small animal remains from sites indeed reflect human dietary patterns. The coprolites reveal that reptiles, birds, bats, and a large variety of rodents were an important and prevalent component of the prehistoric diet