Superconductivity may be the key to electric jet engines for lowering greenhouse gas emissions from aircraft, which contributed 9 percent of the total U.S. greenhouse gas emission in 2003. A study out of Florida A&M and Florida State Universities finds that, for small planes, superconducting turbines would be lightweight and powerful enough to run on electricity from clean-burning hydrogen fuel cells. The liquid hydrogen could also chill the superconductors. But the savings would come at the steep premium of $2 million just for a prototype.
—JR MinkelStem Cell Veto—Again
On June 20, President George W. Bush for the second time vetoed legislation that would have lifted limits on federally funded research on embryonic stem cells. Congressional advocates tried to muster the votes to override the veto but fell short of the two-thirds majority needed. The measure would have allowed research only on cells extracted from unused embryos at fertility clinics that donors chose to give rather than discard. Ironically, the veto came the same day as a Science report that found that 60 percent of patients with surplus embryos in U.S. fertility clinics would likely donate them to create stem cell batches or lines for research; only 22 percent said they would hand them over to other infertile couples.
—Lisa SteinOpening the Door to HIV
The mutation that enabled humans to fend off an ancient monkey virus appears to have made us more vulnerable to HIV-1. Virologists at the Fred Hutchinson Cancer Research Center in Seattle studied the immune protein TRIM5-alpha, which protects rhesus monkeys but not humans from HIV-1. They found that the human version of TRIM5-alpha protected cells against a resurrected portion of the extinct primate retrovirus PtERV1, suggesting that it evolved to fend off the virus. In proving itself against PtERV1, however, the human TRIM5-alpha lost the ability to fight HIV-1, the scientists say in the June 22 Science.