See Inside March 2008

Updates.... Whatever Happened To?

Hoyle's Missing Equation -- Flu Sites -- Artificial Capillaries -- Stubborn Scores

Not Showing His Work
The failure to include a key equation may have kept Sir Fred Hoyle from getting the recognition he deserved for a paper on the formation of elements in stars. Hoyle, who died in 2001 at the age of 86, was something of a tragic scientific figure. He never accepted the big bang theory, preferring instead the idea of a steady-state cosmos; later, he embraced the view that life on Earth originated in outer space. These attitudes probably cost him a Nobel Prize [see the profile of Hoyle, “The Return of the Maverick”; SciAm, March 1995].

But before his scientific infamy, Hoyle made what should have been a lasting contribution with a 1954 Astrophysical Journal paper laying out a process by which stars heavier than 10 suns would burn the hydrogen and helium at their cores into heavier elements through a progressively hotter series of nuclear fusion reactions. When such a star finally exploded in a supernova, it would scatter these elements into space, where they would seed still-forming star systems. Prior to Hoyle’s work, many experts believed that the elements must have been born during the big bang.

Instead of citing the study, researchers discussing the formation of elements, or nucleosynthesis, typically reference a 1957 paper, co-authored by Hoyle, which focused on other facets of the problem, says Donald Clayton of Clemson University, who was a colleague of Hoyle’s. Clayton found that of 30 major nucleosynthesis papers published between 1960 and 1973, 18 cited the 1957 work and only one gave the nod to Hoyle’s 1954 paper.

Writing in the December 21, 2007, issue of Science, Clayton attributes the misplaced citation to the lack of a relatively straightforward equation that was implicit in the 1954 study. “Hoyle’s equation,” as Clayton calls it, relates the mass of heavy elements ejected by dying stars to the rate of their death and the change in abundance of the various isotopes produced during successive nuclear reactions. “He was an expert mathematician,” Clayton remarks. “It’s a shame he didn’t decide to just write the equation.”

Shaping up for the Flu
The next influenza pandemic will most likely occur when a change in an avian or swine flu virus enables it to infect human cells. In the January Nature Biotechnology, scientists report that the critical change will be the virus developing an ability to latch onto a particular variety of the so-called alpha 2-6 glycan receptors on lung cells. These receptors come in umbrella and cone shapes; in humans, the umbrella version, which is more plentiful, opens the door to serious illness. This finding answers such questions as why some flu strains dock at cells but do not infect humans very well (because the viruses have latched onto cone-shaped receptors), and it could provide a way to track flu adaptations as well as to uncover new treatments.

Growing Blood Vessels
As part of the goal of growing replacement organs, researchers have relied on scaffolds that encourage cells to form in particular ways. But they still need to perfect the scaffold materials and geometry, among other factors [see “Tissue Engineering: The Challenges Ahead”; SciAm, April 1999]. In the January 1 Advanced Materials, scientists from the Massachusetts Institute of Technology describe how 600-nano­meter-wide ridges and grooves on a silicone-based substrate provided pathways for flourishing endothelial progenitor cells. Grown three-dimensionally, these cells formed tubes that could serve as capillaries. The challenge remains in getting such constructs into the body.

Lasting Disparity
A study of some 2,000 children observed over seven years supports the nurture side of the IQ debate [see “Unsettled Scores”; SciAm, February 2007]. Researchers tracked residents of six severely disadvantaged neighborhoods in Chicago—almost all African-American—and found significant and stubborn declines in their verbal ability compared with peers in better neighborhoods. Children who moved out of the disadvantaged areas still showed, years later, four-point declines in IQ, equivalent to a year of schooling. The Proceedings of the National Academy of Sciences USA published the findings online December 19, 2007.

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