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Viral Quasispecies

The standard definition of a biological species does not apply to viruses. A more expansive and dynamic view of viral populations holds clues to understanding and defeating them

By Manfred Eigen

Sustaining the Amazon

Can scientists reconcile the inevitability of economic development with the preservation of rain forests?

By Marguerite Holloway

Surgical Treatment of Cardiac Arrhythmias

To save the life of a doomed patient, the author and his colleagues developed a now standard surgical procedure for correcting lethally fast heartbeats in many people susceptible to them

By Alden H. Harken

Risk Analysis and Management

Inadequate approaches to handling risks may result in bad policy. Fortunately, rational techniques for assessment now exist

By M. Granger Morgan

Fuzzy Logic

The binary logic of modern computers often falls short when describing the vagueness of the real world. Fuzzy logic offers more graceful alternatives

By Bart Kosko and Satoru Isaka

Edwin Hubble and the Expanding Universe

More than any other individual, he shaped astronomers' present understanding of an expanding universe populated by a multitude of galaxies

By Donald E. Osterbrock, Joel A. Gwinn and Ronald S. Brashear

Australia's Polar Dinosaurs

Their excellent night vision and apparent warm blood raise a question: Could they have survived icehouse conditions at the end of the Cretaceous period?

By Patricia Vickers-Rich and Thomas Hewitt Rich

Accurate Measurement of Time

Increasingly accurate clocks--now losing no more than a second over millions of years--are leading to such advances as refined tests of relativity and improved navigation systems

By Wayne M. Itano and Norman F. Ramsey


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