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■ Cognitive behavioral therapyseems to help insomniacs,offering an alternative to long-termdrug use. /041101/2.html

■ Scientists created a compositematerial that has a negativeindex of refraction. It may lead to unusual lenses andelectromagnetic devices./040901/3.html

■ Researchers have discovered justhow the mutant protein inHuntington’s disease does itsneuron-destroying job—and havereversed the impending cell deathin the lab dish. /032301/4.html

■ Insulin-like hormones dictate theaging process across severalspecies—a possible explanationfor why low-calorie diets, whichreduce insulin levels, extend life./040601/1.html

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Locating the Latent EnemyFrustrating treatment for HIV-positive patients is the virus’s abilityto hide in T cells. These immune system cells must be turned on by aforeign particle (antigen) but can later turn off and hibernate in theblood for many years. Scientists have found hidden copies of the virusin retired T cells and, more recently, in newborn T cells, which haveyet to be activated. In the April Nature Medicine, researchers suggest that some of these HIV-infected “naive” T cells originate from an HIV-infected thymus, the organ that makes T cellsand releases them into the blood. To test this theory, they added substances that mimicked theaction of a T cell antigen to a culture of HIV-infected thymus tissue that was extracted from amouse. Within 24 hours the amount of viral genes in the culture jumped 30-fold. These resultsmay explain why most patients experience a resurgence in viral levels years after becoming in-fected and may help in developing new therapies against latent HIV. —Alison McCook

BIOLO G Y

Boning UpA purring cat is not necessarily a happy one;many species—including cheetahs and somelions—also purr when wounded or anxious.Some researchers speculate that this lovelyrumble may serve a function: to heal fracturesand strengthen bones. In an as yet unpublishedstudy from the Fauna Communications Re-search Institute in Hillsborough, N.C., inves-

tigators determinedthat the frequency atwhich many catspurr, between 27and 44 hertz forhouse cats, matchesthe frequency thatseems to help hu-man bones strength-en and grow. If cor-rect, the theory mayexplain why catsheal so quickly afterinjury.

—Alison McCook

C OM P U T E R S

Copy UnprotectedIt’s strike one for proponents of hardware-embedded copyright protection. In April thecommittee that designates technology stan-dards voted against a proposal to install aprogram called content protection for re-cordable media (CPRM) directly onto a com-

puter’s hard drive. Opponents have longfeared that CPRM, which would block usersfrom downloading copyright-protected ma-terial, could compromise open-source soft-ware and copying for personal use [see “ToProtect and Self-Serve,” Cyber View, byWendy M. Grossman, March]. But becausecompliance with these technology standardsis voluntary, the group that produced CPRMcan still sell it. —Alison McCook

HIV virus via computer modeling

PURRING as bone builder

S O C IOLO G Y

Aborted CrimeWave, Part 2Two years ago Steven D. Levitt of the Univer-sity of Chicago and John J. Donohue III ofStanford University achieved notoriety byproposing that up to 50 percent of the dropin crime in the 1990s was attributable to thelegalization of abortion: fewer unwanted chil-dren meant less crime. Now another econo-mist has analyzed the same crime data, aswell as other indicators, and has reached adifferent conclusion. “There is nothing tosuggest anything related to legalized abor-tion,” says Theodore J. Joyce of Baruch Col-lege. Based on his analysis, Joyce believes in-stead that the most plausible explanations arethe waning of the crack epidemic and a com-bination of police action, incarceration andeconomic growth. Donohue and Levitt’s re-port, now finally peer-reviewed, appears inthe May Quarterly Journal of Economics.Joyce plans to submit his for publication in afew months. —Marguerite Holloway

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