Given the sparse evidence, it will be difficult for any of them to find clear proof in the near future.
On the one hand, the results should quell skeptics who have contended that there is no clear proof that Iressa works.
The researchers who presented this case study say there is clear proof the infant was infected and that the infection is functionally gone.
But Mr ElBaradei has said the "jury is still out" on whether Tehran is secretly developing nuclear weapons, because he has no clear proof.
It seems inconceivable that we would submit to these risks without a very clear-cut case for the science of global warming and equally clear proof that the proposed remedy will actually mitigate that claimed phenomenon.
How could I stay abreast of what was going on in my house if, when the snow came, my every footstep in the yard would leave a trail of incrimination and such clear proof of a prowler on the grounds as to get Diana on the phone to the town police?
Chris Jones, the chief executive of the MS Trust, said it was "frustrating" that there was no clear physical proof that cannabinoids helped relieve spasticity.
But its biggest and most controversial application is as a hardener for making polycarbonate plastics and epoxy resins the materials of choice for manufacturing clear, shatter-proof bottles, spectacles, medical devices and CDs as well as dental coatings and linings for food cans.
And it's very difficult for the civil liberties organizations to get past this because the standard of proof is not really clear.
And this submission is made even more compelling by the managers own position in which they made clear to you last week that proof of criminal conduct, in their view, was required to justify conviction.
CNN: Transcript: White House Counsel Ruff's opening statement
"They met this morning with the board of directors, it was a positive meeting, they're well intentioned, but it was made clear to them that they need proof of funds before we can continue negotiations, and it's a tall order in a short period of time, " he said.
There is a clear demand for purpose driven products and proof that companies should be driven by values.
FORBES: Net Impact's Army for Good and the Rise of the Enlightened Merchant
It is misleading and unrealistic to expect absolute proof of causation but it is clear that appropriate codes, properly implemented, are associated with a wide variety of favourable outcomes.
"We have no proof, "he cautions, but the implications are clear: Derived from the playthings of nobility, a bourgeois toy became once more a bauble of royalty.
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