Researchers who study the fossil record are seeking to determine whether the impact made by a comet or meteor really did decimate up to half of the life on this planet at the end of the Cretaceous period. Questions whether the extinction of plant and animal life was abrupt, started before the impact, or was a gradual change. (KR)

Reviews current ideas and research findings related to the flow patterns of mantle rocks. Highlights the components of the two-layer convection and whole-mantle models of mantle flow. Proposes that mantle flow is the key to understanding how the earth has cooled and chemically evolved. (ML)

Describes the theory and application of an atomic fountain which pushes the atoms by laser pulses. Discusses the applications in measuring atomic properties and in building an atomic clock. (YP)

Reviews the Science Talent Search scholarship program which rewards scientific research efforts of secondary students. Also includes a description of this year's ten top winners and their projects. (SL)

Reviews cases which support the view that parts of the left hemisphere control languages, no matter how it is expressed, while right-side regions are involved only in skilled nonlinguistic movements and perceptions. Compares recent findings with previously held theories. (ML)

This is a review of important science news stories of 1990 as reported in the pages of this journal. Areas covered include anthropology, astronomy, behavior, biology, biomedicine, chemistry, computers and math, earth sciences, environment, food science, materials science, paleobiology, physics, science and society, and space sciences. (CW)

Reviews the findings of the White House Science Council's survey of the condition of the United States university-research community. Indicates the problems that threaten the quality of academic research and outlines recommendations for its improvement. Funding changes, tax credits, and scholarships are among the panel's suggestions. (ML)