The second desideratum, of low thermal and high electrical conductivity, was achieved by dividing the bismuth telluride into pellets a few nanometres across.

ECONOMIST: Solar power

If he actually weighs 110kg he will be eating 3, 080 calories to maintain his extra flesh and he thus needs to make a permanent cut of 786 calories from his daily diet if he is to get back to the 70kg desideratum.

ECONOMIST: The difficulty of losing weight is captured in a new model