A better way
The article “Thinning fuel before injection boosts efficiency” (SN: 10/25/08, p. 9) shows that there are many ways to find efficiency when we look. One place I see for improvement is moisture injection in the feed airstream to gasoline engines. Here in the Southwest, where humidity runs at 20 percent, rainy days are associated with an increase in gas mileage because the moisture turns to steam in the engine and improves efficiency. Moisture injection should be less complex to accomplish than adding a strong electric field.
Michael Daly, Gallup, N.M.

Good degradation
The deterioration of plastics described in “Long live plastics” (SN: 11/8/08, p. 34) has a brighter side: All those plastic items in landfills won’t last forever.
Paul Etzler, Cedar City, Utah

Plastic items in landfills may not last forever, but plastics aren’t going away tomorrow either. In landfills, sunlight and oxygen the two biggest threats to plastics and many other materials are in short supply.  Landfills are more like a tightly sealed storage container than a compost pile, says Wilson Hughes, a waste reduction planner for the City of Tucson, Ariz. Even plastics designed to be biodegradable won’t disappear quickly in a landfill. — Sid Perkins

The element of choice
Nora Volkow, NIDA director, is right on target with her four-point agenda to replace outdated and stigmatized thinking with addiction approaches that work (“It’s time for addiction science to supersede stigma,” SN: 11/8/08, p. 40). However, her view that chronic addiction is a disease of the brain does not rule out the large volitional component assigned to “achieved” stigmas involved in addiction treatment. All addiction is a choice; otherwise no one would ever recover from an addiction. Admittedly it is a very difficult choice in the middle of a craving or when a person is biologically heavily weighted toward addiction. All recovery starts with choice, no matter what the psychobiology.
Gene Tinelli, Syracuse, N.Y.

Correction: A timeline with “David, Solomon may have been kings of copper” (SN: 11/22/08, p. 10) incorrectly labeled the Iron and Bronze ages.  Though scholars debate exact start dates, the Bronze Age began around 3500 B.C. and the Iron Age followed, beginning around 1200 B.C.