Investigations

Citations

Skinny science
Thin is in, especially among physicists who want to create microscopic materials for use in fiber optics, electronics, and other industries. Scientists already have shown they can make liquid threads 10 microns in diameter—slimmer than a strand of human hair. Assistant physics professor Wendy Zhang believes they can go further, suggesting in the October 29 Physical Review Letters that smaller sizes could theoretically be achieved by manipulating air bubbles in a process called viscous entrainment. The concept awaits testing in the lab.

Jason Smith

Zhang observes liquid air bubbles.

Seminal finding
Sexual competition among males has reached a new low: it’s evident at the molecular level. A protein regulating semen viscosity evolves more rapidly in primate species whose females have multiple partners, a team led by human-genetics assistant professor Bruce Lahn reports in the December Nature Genetics and the November 7 online edition. The protein, semenogelin, determines the secretion’s post-ejaculation strength—from liquid substance to solid plug, preventing fertilization by subsequent suitors. Sequencing the semenogelin gene in a variety of primates, the researchers found that when females are promiscuous males face selective pressure to make their semen more potent, an adaptation that translates into larger testicles and sperm counts.

A neck apart
Putting the terrible in “terrible-headed lizard from the Orient,” researchers in Chicago and China have solved the mystery of how Dinocephalosaurus orientalis got its lunch. The Triassic Period protorosaur used its long, hose-like neck to sneak up on—and suck up—unsuspecting prey, reports a team including Michael LaBarbera, professor of organismal biology & anatomy and geophysical sciences, in the September 24 Science. After studying a 230-million-year-old fossil of the species, discovered in China’s Guizhou province two years ago by Chinese paleontologist Chun Li, the scientists concluded that the creature’s five-foot neck—almost twice as long as its body—served as a lethal vacuum.

Supersize sleep
Sleep deprivation hinders appetite control, new findings have shown. A team led by endocrinology professor Eve Van Cauter reports in the November Journal of Endocrinology & Metabolism that a lack of ZZZs can diminish the hormone leptin, which tells the brain whether the body needs more food. The researchers studied 11 healthy 22-year-old men, comparing their leptin levels after four and eight hours of snoozing. When sleep—and thus leptin—is in short-supply, people tend to overeat, the team concluded. The hormone is widely thought to hold the key to understanding obesity.

Big bang, big whoop
The big bang may not be such a big deal, according to University physicists. Taking some wind out of the prevailing scientific theory explaining the universe’s origin, assistant physics professor Sean Carroll and graduate student Jennifer Chen argue on the Cornell University Web site arXiv.org that the world’s entropy is infinite. Previous theories have assumed the opposite. Supposing that energy could always increase, Chen and Carroll project that big bangs could happen repeatedly over incredibly long periods of time. They further theorize that a fluctuation in a preexisting universe could have set off the famous explosion 10 to 20 billion years ago.—M.L.