Enter the dragon - as source of new antibiotic?
Biochemists may have discovered a type of antibiotic that sounds like something out of a fairy tale: It is based on dragon blood.
Scientists from George Mason University in the US recently isolated a substance in the blood of a Komodo dragon that appeared to have powerful germ-killing abilities.
Inspired by the discovery, they created a similar chemical in the lab and dubbed it DRGN-1.
Tests on mice that were given skin wounds infected with two types of bacteria showed that DRGN-1 had three valuable properties: It punched holes in the outer membranes of both Gram-negative and Gram-positive bacteria, it dissolved the biofilms that glue bacteria together, and it sped up skin healing.
The research was published in the journal Biofilms and Microbiomes. The work was funded by the US military's Defence Threat Reduction Agency, but the discoverers are seeking drug-industry backing too.
The study's lead authors Monique Van Hoek and Barney Bishop focused on crocodilians and monitor lizards because they can survive grievous wounds, including lost limbs, in filthy environments without getting infected. It is unclear how Komodo dragons kill prey, Mr Bishop said. They have serrated teeth and their mouths teem with bacteria, so it was long believed that sepsis caused by the bacteria weakened their larger victims, like deer. But in 2009, Australian researchers discovered that the dragons also inject a shock-inducing venom.
NYTIMES
A knotty problem unravelled
Researchers at the University of California, Berkeley, have unravelled one of life's enduring mysteries: Why do shoelaces come undone?
The researchers - professor of mechanical engineering Oliver O'Reilly and PhD students Christine Gregg and Christopher Daily-Diamond - reported that the force of your foot striking the ground and the motion of your leg combine to help loosen and ultimately untie the knot.
When running, the foot hits the ground at about seven times the force of gravity. That impact is transmitted to the knot, which stretches and relaxes in response. As the knot loosens, swinging legs apply an inertial force on the free ends of the laces and - voila! - pretty soon your laces are flopping around.
The study identified "strong" knots, those associated with square knots, and "weak" ones tied like a "granny" knot.
For a quick way to know which is which, look at the loops of your laces. A weak knot will typically have one loop pointing towards the toes and one towards the ankle. A stronger knot typically has the loops oriented on opposite sides of each other.
Initial experiments involved so-called barefoot running shoes, dress shoes, running sneakers and hiking boots.
Ms Gregg said she spent hours sitting on a table, swinging her legs to see if the movement had any effect on the knot. It did not, and neither did merely stomping her feet. But the force of her feet hitting the floor when she was walking or hitting the treadmill when she was running, combined with her gait, eventually caused the shoelaces to come undone. In an article in The Proceedings of the Royal Society A, the researchers wrote that the unravelling was "a sudden and catastrophic phenomenon".
How significant is this research? It has practical applications to things like improving surgical sutures, Professor O'Reilly said.
NYTIMES
Why crossing the street is no child's play
Children under certain ages lack the perceptual judgment and motor skills to cross a busy road consistently without putting themselves in danger, says a new University of Iowa study.
The researchers placed children aged six to 14 in a realistic simulated environment and asked them to cross one lane of a busy road multiple times.
The results: children up to their early teenage years had difficulty consistently crossing the street safely, with accident rates as high as 8 per cent for six-year-olds, said the university in a statement.
Only by age 14 did children navigate the street crossing without incident, while 12-year-olds mostly compensated for inferior road-crossing motor skills by choosing bigger gaps in traffic, the study revealed.
"Some people think younger children may be able to perform like adults when crossing the street," said Professor Jodie Plumert of the university's Department of Psychological and Brain Sciences. "Our study shows that's not necessarily the case on roads where traffic doesn't stop."
For parents, that means taking extra precautions. Be aware that your child may struggle with identifying gaps in traffic large enough to cross safely. Young children also may not have developed the fine motor skills to step into the street the moment a car has passed, unlike adults have mastered. And, your child may allow eagerness to outweigh reason when judging the best time to cross a busy street.
The study was published in the Journal of Experimental Psychology: Human Perception and Performance.
