Shriver, through laws and the foundation, has helped knock down external barriers for the mentally retarded.

However, as we shall see, we do have firmer evidence to suggest that non-enrollers are more affected by external barriers such as financial and personal circumstances.

The creatures below are all the same species as they all appear to be capable of interbreeding provided that the external barriers between them where removed.

She thumbed the window button and waited for a gap to open in the large external barrier before sliding through to the street.

(Cancer is always associated with 'protection' by utilizing an external barrier).

Therefore, hospitals said they would erect external barriers and call for police assistance if swelling crowds became unruly. . . .

Separation does not necessarily imply any external barriers or even the occupation of separate districts.

Sialic acid carries a negative charge, providing an external barrier to charged particles.

Unless there is a significant external barrier to change (like the iTunes store or the Windows distribution monopoly), then the leader appears to fade.

For a transitional period, industrial policy should include the option of erecting external barriers in some sectors to allow them to restructure and modernise.