Fingerprint scanners are now fitted as standard in many laptops and provide an effective barrier to snooping.

People want to feel that you are a bit like them; money provides a very effective barrier.

Completed packages, however, involve heat seals, joints, and closures which often reduce the effective barrier of the package.

High mountainous areas and undulating terrain between the transmitter and receiver can form an effective barrier to tropospheric signals.

Abnormalities in lipid transport prevent the skin from forming an effective barrier and result in the hard, thick scales characteristic of harlequin ichthyosis.