In public imagination, the sabre-toothed cat Smilodon ranks alongside Tyrannosaurus rex as the ultimate killing machine. Powerfully built, with upper canines like knives, Smilodon was a fearsome predator of Ice-Age America's lost giants.

For more than 150 years, scientists have debated how this iconic predator used its ferocious fangs to kill its prey. Now a new Australian study, published today in the US Proceedings of the National Academy of Science, hopes to lay the arguments to rest. And the results will put in dent in Smilodon's reputation.

Scientists from the University of New South Wales and University of Newcastle have used a computer-based technique called Finite Element Analysis (FEA) to test the bite force and feeding mechanics of the fearsome predator.

Hair samples from naturally preserved child mummies discovered at the world's highest archaeological site in the Andes have provided a startling insight into the lives of the children chosen for sacrifice. Researchers funded by the Wellcome Trust used DNA and stable isotope analysis to show how children as young as six years old were 'fattened up' and taken on a pilgrimage to their death.

A team of scientists led by Dr Andrew Wilson at the University of Bradford analysed hair samples taken from the heads and from small accompanying bags of four mummies found in the Andes.

Early findings by Carnegie Mellon University researchers suggest that people who are suckered by a spoof email into visiting a counterfeit Web site are also people who are ready to learn their lesson about “phishing” attacks.

Phishing attacks have become a common method for stealing personal identification information, such as bank account numbers and passwords. Lorrie Cranor, associate research professor of computer science, said phishing often is successful because many people ignore educational materials that otherwise might help them recognize such frauds.

Current recommendations developed by the Institute of Medicine in 1990 suggest women should gain at least 15 pounds during pregnancy and places no upper limit on pregnancy weight gain.

Not a good idea, says Raul Artal, M.D., chairman of the department of obstetrics, gynecology and women’s health at Saint Louis University School of Medicine.

“Guidelines for nutrition during pregnancy at that time were based solely on expert opinion and not on scientific data. Obesity was not the problem it is now,” Dr. Artal says.

A new study led by Artal,published in the October issue of Obstetrics & Gynecology, found that women of different weights should gain or even lose different amounts of weight.

Comets are made of the most primitive stuff in the solar system. As hunks of rock and ice that never coalesced into more planets, they give researchers clues to the evolution of solar systems.

In February, during its mission to study the sun's polar regions, the spacecraft Ulysses flew through McNaught's ion tail 160 million miles from the comet's core.

Instrument readings showed there was "complex chemistry" at play, said University of Michigan space science professor George Gloeckler. Gloeckler is the principal investigator on the Solar Wind Ion Composition Spectrometer (SWICS) aboard Ulysses, which measured the composition and speed of the comet tail and solar wind.

According to an analysis by Dr. Kathryn Wilson, associate professor of economics at Kent State University and colleagues, the United States has the highest level of income inequality among all rich nations. For example, low-income households, or those at the 10th percentile of the income distribution, spend approximately $8,900 per year per child, while high-income families, or those at the 90th percentile, spend $50,000 per child.

“People like to think of America as the land of opportunities,” says Wilson. “The irony is that our country actually has less social mobility and more inequality than most developed countries.”