1.   At this stage of research, scientists cannot firmly link global warming to changes in circulation patterns.

2.   Concern about water scarcity has heightened because of a recent drought in northern regions, which some scientists fear is linked to global climate change.

3.   More recently, other scientists have linked the bacterium, known as Helicobacter pylori, to cancer of the stomach.

4.   Some scientists have linked these animal ailments, and more, to man-made chemicals that interfere with hormone systems.

5.   The discovery, reported Friday in the journal Science, is the second genetic variant scientists have linked to extended symptom-free life with HIV.

6.   The ingredient is phenylpropanolamine, which scientists have recently linked to a slight risk of stroke in young women.

7.   The ingredient is phenylpropanolamine, or PPA, which scientists have recently linked to a slight risk of stroke in young women.

8.   While some scientists have linked them to primates, others have insisted that they are related to lagomorphs, the group that includes rabbits and hares.

9.   Years of detective work finally allowed the Marshall scientists to link the bursts to thunderheads, and their paper appeared in Science last May.

10.   A similar illness in humans known as Creutzfelt-Jakob has killed at least eight people in Britain, where some scientists have linked the two diseases.