21.   In examining the causes of problem pregnancies, medical researchers increasingly study lifetime stress, not only stress during pregnancy.

22.   In the hope of understanding more about pain perception, researchers are studying changes in spinal cord neurons that transmit pain messages to the brain.

23.   In the case of the cancer drug, for example, researchers studied a class of enzymes involved in cell division and proliferation.

24.   In the women who developed breast cancer, the researchers studied prescription records in the five years that ended a year before the cancer was diagnosed.

25.   In the fruit fly study, researchers studied molecules, known as hydrocarbons, on the fruit flies Drosophila serrata and Drosophila birchii.

26.   In the past, researchers have studied both the signals that males send to females and the sensory systems of females that perceive those signals.

27.   Its researchers study not only the possibility of alien life but how life began and evolved on Earth.

28.   Legitimate researchers were studying the substance for its positive effect on inducing deep sleep, increasing growth hormone, and treating narcolepsy and related disorders.

29.   Meanwhile, other researchers are studying how consolidants work long term, a major area of concern.

30.   Miller said the researchers next will study the effect of computer training on reading problems.