They lose effectiveness as more people use a browser session because they are targeted to the concept that one browser represents an interest profile of one person.

ENGADGET: Editorial: We, the digitally naked

Antibiotics lose their effectiveness over time, as bacteria naturally evolve and mutate, becoming resistant.

WSJ: WHO Calls for Action on Superbugs

And already, we're seeing that this home buyer tax credit is starting to lose its effectiveness.

FORBES

"He may lose some effectiveness as an independent, " Sessions said.

CNN: Jeffords split with GOP could hamper Bush agenda

As the anti-icing fluids lose their effectiveness in flight, the aircraft is still equipped with systems that prevent frozen precipitation from building on the wings, tail and various sensors around the airplane.

CNN: Airplane deicing: The how and why

The expected fightback was simply not allowed to happen, Pakistan aware that a full ball would zip through with swing and seam but a short one would lose pace and effectiveness.

BBC: Pakistan dominate as Australia collapse at Headingley

"Whatever your conclusions in this critically important matter, your ultimate decision must focus foremost on a single question: "What do our armed forces gain - or what do they lose - from repeal of a law crafted to ensure their effectiveness in accomplishing the sole reason for which they exist?

CENTERFORSECURITYPOLICY: Gen. Carl Mundy: Don't Ask, Don't Tell