Verbs evolve and homogenize at a rate inversely proportional to their prevalence in the English language, according to a formula developed by Harvard University mathematicians who've invoked evolutionary principles to study our language over the past 1,200 years, from "Beowulf" to "Canterbury Tales" to "Harry Potter."

Writing this week in the journal Nature, Erez Lieberman, Jean-Baptiste Michel, and colleagues in Harvard's Program for Evolutionary Dynamics, led by Martin A. Nowak, conceive of linguistic development as an essentially evolutionary scheme: Just as genes and organisms undergo natural selection, words -- specifically, irregular verbs that do not take an "-ed" ending in the past tense -- are subject to powerful pressure to "regularize" as the language develops.

In Sweden the welfare system allows for generous maternity leave, long spells of sickness absence with almost full compensation and opportunities to work part time.

The result: women on long term sick leave outnumber men two to one, reveals research published in the online open access journal BMC Public Health. Factors associated with taking long term sick leave among women in study were a self-reported lack of competence for work tasks, high physical and mental demands at work and not enough flexibility or influence over their working lives.

93% of women on sick leave wished to return to work. Although the number of sick leave days claimed ranged from 90 to 381, almost three quarters believed they would return to work within two years.

The majority of non-medical anabolic-androgenic steroid (AAS) users are not cheating athletes or risk-taking teenagers, according to a recent survey published in the Journal of the International Society of Sports Nutrition.

Instead, the typical male user is about 30 years old, well-educated, and earning an above-average income in a white-collar occupation. The majority did not use steroids during adolescence and were not motivated by athletic competition or sports performance.

The study, containing the largest sample to date, was coordinated by Jason Cohen, Psy.D. candidate, using a web-based survey of nearly 2,000 US males.

Planetary scientists on both sides of the Atlantic have tracked down a rare molecule in the atmospheres of both Mars and Venus. The molecule, an exotic form of carbon dioxide, could affect the way the greenhouse mechanism works on Venus.

The discovery is being announced today at the annual meeting of the American Astronomical Society’s Division of Planetary Sciences in Orlando, Florida. Its presence could affect the way the greenhouse mechanism works on Venus. The mystery began back in April 2006, soon after ESA’s Venus Express arrived at the second planet in the Solar System.

The ability to tactually recognize fine spatial details, such as the raised dots used in braille, is especially important to those who are blind. With that in mind, a team of researchers has identified the neural circuitry that facilitates spatial discrimination through touch. Understanding this circuitry may lead to the creation of sensory-substitution devices, such as tactile maps for the visually impaired.

The research team, led by Krish Sathian, MD, PhD, professor of neurology in Emory University School of Medicine, included first author Randall Stilla, research MRI technologist at Emory, and Gopikrishna Deshpande, Stephen Laconte and Xiaoping Hu of the Coulter Department of Biomedical Engineering at Georgia Tech and Emory.

A new study indicates that a popular type of genetically engineered corn--called Bt corn--may damage the ecology of streams draining Bt corn fields in ways that have not been previously considered by regulators. The study appears in the Oct. 8 edition of The Proceedings of the National Academy of Sciences.

This study provides the first evidence that toxins from Bt corn may travel long distances in streams and may harm stream insects that serve as food for fish.