21.   Aggressive moves by the U.S. to lessen the trade gap by promoting exports can only exacerbate an already tense relationship between the two nations, the authors said.

22.   Air temperatures soared higher than expected and the light filtering through glass panes was surprisingly dim, the authors say.

23.   All the other countries have national health insurance of some form, which gives them clout in negotiations with big pharmaceutical companies, the study authors say.

24.   But before then, further studies of both sexes are needed to confirm their findings, the authors said.

25.   But beyond that, the authors said, the study suggests that ethnicity may need to be taken into account regularly when determining proper medicine doses.

26.   But it also appears to help restore blood flow by opening blood vessels and helping the body fight blood clots, the authors said.

27.   But its authors say it may not be a bad thing.

28.   But its authors said the problem of weeding out inappropriate, overly aggressive care is much more complex than most Americans, including policymakers, have assumed.

29.   But several authors said that other major publishers are beginning to raise the idea.

30.   But the authors said many questions remained, among them whether the enterovirus scraps bring about neuron death or simply represent an irrelevant, associated phenomenon.