On the Other Hand
Double-hand transplantations could switch the handedness of patients. Two men who lost both hands in work injuries received transplants after three to four years of waiting. Despite such a long time—the brain typically reassigns areas linked with control of the amputated limb to other muscles—researchers at the French Center for Cognitive Neuroscience in Lyon found the patients’ brain could connect to the new hands, which subsequently could perform complex tasks (in a demonstration, one patient repaired electrical wires). Although both men were right-handed, their left hand connected with their brain at least a year sooner than their right hand did, and they stayed left-handed. The reason for this switch, reported online April 6 by the Proceedings of the National Academy of Sciences USA, is unclear—perhaps the prior dominance of the right hand made the corresponding brain regions less flexible to reconnections or the surgeries were done slightly differently.  —Charles Q. Choi

Point Taken
Every year hundreds of thousands of people develop medical complications such as nerve injury when hypodermic needles penetrate deeper than they should. A novel needle devised by researchers at Harvard Medical School and their colleagues automatically stops itself from going too far. The force from the first push of the device’s plunger goes only to a blunt, flexible wire inside the hollow needle. As long as this filament remains unbent, a special clutch keeps the rest of the needle from advancing. On encountering resistance from tissue, the wire buckles and the clutch permits the entire needle to move forward. On reaching a target cavity, such as a blood vessel, the filament no longer faces resistance and so straightens out, preventing the needle from proceeding but uncovering the tip to allow medicine out. Described in the April 7 Proceedings of the National Academy of Sciences USA, the needle might reach clinics in three to five years.  —Charles Q. Choi

Living Alike
The Geico “caveman” advertising campaign might be on to something. Evidence presented in April at the Paleoanthropology Society meeting in Chicago suggests that Neandertal behavior resembled that of early modern humans. Bruce Hardy of Kenyon College studied artifacts from Hohle Fels, a site in southwestern Germany. It contains tools made by Neandertals between 36,000 and 40,000 years ago as well as items manufactured by early modern humans between 33,000 and 36,000 years ago. Both groups lived under similar environmental conditions at this site, making their cultural remains ideal for comparison. Hardy examined the wear patterns and residue on the tools and found that although modern humans had a larger range of implements, both groups engaged in similar activities, such as using tree resin to bind stone points to wooden handles and crafting tools from bone and wood. He speculates that the Neandertals did not invent more tools because they could survive just fine with what they had.  —Kate Wong

Electromagnetic Chatter
Single-celled organisms may communicate via radiation. Daniel Fels of the Swiss Tropical Institute in Basel grew the microbe Paramecium caudatum in complete darkness in clear tubes, which prevented the cells from passing chemical messages to one another. Fels discovered the microorganisms could influence the feeding behavior and growth rates of neighbors in other tubes, suggesting that electromagnetic signals were involved. The microbes seemed to use at least two frequencies to communicate, one of which was in the ultraviolet (UV) range. For instance, small populations of paramecia grew significantly better when separated from larger ones by glass that blocks UV light than by quartz glass, which permits UV rays. The cellular structures behind these messages have not yet been identified, but in the April 1 PLoS ONE, Fels suggests that these signals could lead to novel noninvasive medical techniques.  —Charles Q. Choi

Laser Beams That Curve
Two years ago physicists demonstrated that a laser beam traveling through the air can bend slightly if certain components are asymmetrical, forming what is called an Airy beam. Now researchers have shown that pulsed, high-intensity versions can leave curved trails of plasma. Shot out like a stack of pennies, each pulse, one centimeter wide and lasting 35 femtoseconds, passes through a glass plate that turns it into a triangular shape, in which an intense peak falls on one side of several weaker peaks. The brightest part heads in one direction, while the dimmer ones go the opposite way. (The momentum of the entire pulse remains straight, however.)

Being extremely intense, the bright spots ionize the air behind them and leave a curved plasma stream in their wake. The self-bending beam, described in the April 10 Science, does not curve by more than the beam’s diameter, but that amount is enough to help physicists probe the structure of laser pulses.  —Larry Greenemeier

Calorie-Burning Fat
Once thought to disappear after infancy, the calorie-burning tissue known as brown fat may actually be keeping some adults slim. Newborns have brown fat to help generate body heat, but it seems to melt away as part of the aging process. A new study shows that some adults, especially those with a healthy body mass index, maintain reserves of the good fat that is metabolically active. The work, published in the April 9 New England Journal of Medicine, could potentially point to novel obesity-fighting compounds. —Coco Ballantyne

Have a Nice Trip
Man’s best friend could be one of man’s biggest hazards. Pets cause nearly an estimated 87,000 falls that need emergency room treatment every year in the U.S., according to the March 27 Morbidity and Mortality Weekly Report. A quarter of the tumbles happened when owners were walking their dogs, and twice as many women as men were hurt. Most injuries occurred in children and those 35 to 54 years old, but people 75 or older suffered the most serious damage.  —Jordan Lite

Eggs Not Over Easy
Infertility treatments operate under the assumption that women are born with all the eggs they will ever have. But researchers reporting online April 14 in Nature Cell Biology claim they have found precursor stem cells in newborn and adult mice that could be prodded into producing new eggs. The scientists grew these cells in a petri dish and implanted them in mice engineered to be infertile. Although some of the mice subsequently gave birth, more studies will be needed to confirm the results.  —Jordan Lite

Note: This article was originally published with the title, "News Scan Briefs".