They are borrowers that are thought, by the various models, to be likely to fail to pay on their mortgage and to have to be foreclosed; often low income, but also they're people with poor credit histories.
The low emission zone - which begins in February 2008 - aims to deter the most polluting vehicles from being driven in central London by imposing charges on lorries, coaches and buses that fail to meet low emission standards.
Christensen's 1997 book, The Innovator's Dilemma: When New Technologies Cause Great Firms to Fail, describes how new, low-quality products can threaten established ones--such as Nintendo toy cameras threatening mighty Kodak.
