The shift, little noticed outside the medical establishment but already controversial inside it, suggests that doctors are starting to redefine their roles, from being concerned exclusively about individual patients to exerting influence on how healthcare dollars are spent.

Swedish family-friendly policies tend to exert a negative influence on women's careers.

Rising population combined with improved nutrition standards and shifting dietary preferences will exert pressure for increases in global food supply.

Oil prices may exert influence not only on American government policies but on how energy is used in the nation.

That's partially because it appears people who set realistic goals actually work more efficiently, and exert more effort, to achieve those goals.

And yet, the same motivation that can push people to exert more effort in a constructive way could also motivate people to be more likely to engage in unethical behaviors," says Maurice Schweitzer, an associate professor at Penn's Wharton School