Feature

  1. Health & Medicine

    What Activates AIDS?

    New studies suggest that a natural process called immune activation—the signaling that alerts immune cells of foreign invaders—plays a key role in explaining why infection with the human immunodeficiency virus progresses to AIDS more quickly in some people than in others.

    By Damaris Christensen
  2. Earth

    The Air That’s Up There

    Researchers are exploring how trees affect the chemistry of the atmosphere.

    By Jessica Gorman
  3. Tech

    Deep Vision

    Increasingly available virtual-reality gear gives scientists, engineers, and planetarium visitors new perspectives.

    By Peter Weiss
  4. Tech

    Bugs on Mars

    Undaunted by the hurdles on flight posed by thin air and a lack of oxygen, aerospace engineers are devising extraordinary flying machines resembling giant insects and windmills to make the exploration of Mars more rapid and effective.