We establish a relation between concurrence and entanglement witnesses. In particular, we construct entanglement witnesses for three-qubit W and GHZ states in terms of concurrence and different set of operators that generate it. We also generalize our construction for multi-qubit states.

Editor—Sydor and colleagues studied trainee behaviour in a crisis situation, and trainee ability to challenge a decision by a consultant anaesthetist to administer blood to a patient who is a Jehovah’s Witness. This was described as unethical, although perhaps a better term would be ‘in breach of the law’. I would like to put it to the authors that unless the notes were shown to contain the pro...

OBJECTIVE To obtain baseline data on the health status and use of health services of children exposed to violence in their families. METHOD The study used data from the first cycle of the National Longitudinal Survey of Children and Youth (1994/95). According to parental reports, 8.6% of children (n = 1,648; representing 329,657 children) aged 2 to 11 years witnessed some violence in their fa...