The theory of entanglement explains a newly observed behavior in a symmetrical hydrogen molecule: When the molecule fractures, the directions in which its constituent particles move are not always random. (p. 141)

A study of mice has identified a biological mechanism by which medications called atypical antipsychotics cause people to gain weight. (p. 141)

A new compound that inhibits the activity of the alertness-promoting brain peptide orexin shows promise as a potential sleeping pill. (p. 110)

A controversial trial of a chemically modified fat called an interesterified fat suggests that it is more harmful than is a partially hydrogenated vegetable oil.

A controversial trial of a chemically modified fat called an interesterified fat suggests that it is more harmful than is a trans fat–rich, partially hydrogenated vegetable oil. (p. 84)

Twenty young women and 20 young men aced an early challenge in their scientific careers by becoming finalists in the annual Intel Science Talent Search. (p. 70)

Regular use of aspirin may prevent healthy adults from developing asthma. (p. 52)

A medication widely used for heart failure may be most effective in people who have a common variant of a particular gene. (p. 46)

Hamsters and other pet rodents are probably underappreciated spreaders of salmonella bacteria. (p. 46)

Certain areas of North America are particularly susceptible to environmental accumulation of mercury. (p. 45)

The nutrient folic acid is generally good for brain health, but research now suggests that too much of it might harm people who get too little vitamin B₁₂. (p. 19)

Vaccination can prevent three of every four flu infections, even when the vaccines are imperfectly tailored to block the common wintertime pathogens. (p. 390)

Forest fires mobilize mercury from the soil and can send the toxic metal into nearby streams and lakes where it accumulates in fish. (p. 372)