Four main factors affect the pace and completeness of decay. The most important is temperature: the rate of chemical reactions in a cadaver doubles with each 10 degree Celsius rise. Humidity or water from the environment buffers those reactions, slowing their effects. Extreme acidity or alkalinity hastens how quickly enzymes degrade biological molecules--although again, the presence of ample water can mediate the effects. Finally, anything that blocks exposure to oxygen, such as burial, submersion or high altitude, will slow decomposition. Depending on the interplay of these four factors, the body can turn into a skeleton as rapidly as two weeks or take more than two years.

Mosquitoes that carry the Plasmodium parasite cause some 300 million cases of malaria every year, claiming one million lives. That's a lot of carnage generated by an insect smaller than a pinky fingernail--but if enterprising researchers have their way, their blood-thirsty assault won't continue much longer. Here are some of the most promising strategies for wiping out malaria-carrying mosquitoes:

These issues are not academic. They raise questions about health care costs--is it worth using expensive machinery on a body that is for all intents and purposes dead?--as well as about dignity in end-of-life care. This year’s “death panel” subplot of the health care debate fed off the real fears people have about being taken advantage of when at their weakest.

In the past 10 years my research group at the California Institute of Technology has developed a new form of imaging, unveiling motions that occur at the size scale of atoms and over time intervals as short as a femtosecond (a million billionth of a second). Because the technique enables imaging in both space and time and is based on the venerable electron microscope, I dubbed it four-dimensional (4-D) electron microscopy. We have used it to visualize phenomena such as the vibration of cantilevers a few billionths of a meter wide, the motion of sheets of carbon atoms in graphite vibrating like a drum after being “struck” by a laser pulse, and the transformation of matter from one state to another. We have also imaged individual proteins and cells.