Thinking tough

Tough times call for tough decisions.

Tough spiders

Spider graphs are the intersection graphs of subtrees of subdivisions of stars. Thus, spider graphs are chordal graphs that form a common superclass of interval and split graphs. Motivated by previous results on the existence of Hamilton cycles in interval, split and chordal graphs, we show that every 3/2-tough spider graph is hamiltonian. The obtained bound is best possible since there are (3/...

Tough Mining

Caenorhabditis elegans, a 1-mm soil-dwelling roundworm with 959 cells, may be the best-understood multicellular organism on the planet. As the most " pared-down'' animal that shares essential features of human biology—from embryogenesis to aging—C. elegans is a favorite subject for studying how genes control these processes. The way these genes work in worms helps scientists understand how dise...

It's Tough...

?for This is a small booklet prepared by the Brother and Sister group of the Association ?-the Help of Retarded Children in New York. It is written to help children who have retarded brother or sister, and summarises such problems as how to accept the situate11' It also gives practical suggestions, such as activities the family can do together. The ide of such a booklet and the points discussed...

Sterilization - Tough on Germs, Tough on Plastics, too

electing the most appropriate plastic material for a medical device is no easy task. Designers must balance cost-containment pressures that favor using the least-expensive material and S processing techniques against the need to ensure the patients’ safety and wellbeing at any cost. Product liability also is a concern. So for any given application, the designer ends up specifying the most affor...