As with a faulty assembly line, when defects go unspotted until the end of the process it is usually too late to fix them.

ECONOMIST: Education

This is a fractious, finicky process and tiny defects in the materials, or failures in the alignment of the different layers, can result in 20% or more of a batch being scrapped.

ECONOMIST: Electronic screens as thin as paper are coming soon

Only 0.6% of the embryos created survived, and it is thought likely that defects in the imprinting process may cause the surviving adults to develop rare diseases later in life.

ECONOMIST: A ��virgin birth�� in mice