You are currently logged out. Please sign in to download the issue PDF.
Explosive growth has been caused by a rapid decrease in the death rate since World War II. The decrease has slowed, but even if it resumed its former pace, the ultimate effect on population size would be small
An "atom" made up of a heavy quark and an antiquark provides the best available system for examining the forces that bind together the elementary constituents of subnuclear particles
Nuclear magnetic resonance, or NMR, can reveal the distribution of atoms in a sample of material. It can do the same in the body, generating images of internal structure without the use of X rays
Segments of DNA and RNA are shuffled and joined in various ways as cells of the immune system develop. The combinatorial process can generate information specifying billions of different antibodies
Flatfishes have both eyes on one side of the head, and in most Ratfish species the eyes are predominantly on the left side or the right. Is there some adaptive reason for this "handedness"?
The violent activity at the center of many galaxies is manifested in the production of narrow, focused streams of ionized gas. Some are a few light-years long; others are a million times longer
Pope Gregory XIII began the modern calendar 400 years ago in order to correct the accumulating drift in the Julian calendar and keep Easter in the spring
A new approach to the cloning, or asexual propagation, of plants starts with living cells that have been stripped of their outer wall. The method yields variants that promise future crop improvements