What the scientists are saying…
Paralysed mice walk again
Paralysed mice have walked again, after being injected with a protein-based gel, raising hopes that a simple jab could one day restore movement to humans with spinal cord injuries. Made of individual protein units that bind together in water to form long chains, the gel works by creating a scaffold on which cells can grow. It also sends signals that trigger the regeneration of nerve cells and blood vessels, and the removal of scar tissue that would normally block cell regeneration. A team at Northwestern University in the US gave mice whose back legs were paralysed either a single injection of the gel, at the site of their injury, or a placebo. Four weeks later, they tested their ability to walk, and scored them according to various factors including their ankle movements, stability and step patterns. Overall, the scores of the mice who had received the gel treatment were three times higher than those of the control group. The researchers are now hoping to get approval for human trials, reports New Scientist. “It would be very exciting if this finding could translate to humans, though issues of scaling mouse therapies to humans are not trivial,” commented Dr Ann Rajnicek of the University of Aberdeen.
The speed of a finger snap
When you snap your fingers, the tip of the “clicked” digit typically reaches the palm in just seven milliseconds, making this movement 20 times faster than the blink of an eye. And though the rotational velocity involved is not the greatest the human body achieves – that distinction goes to the arm of a professional baseball pitcher – the snap does involve the fastest acceleration the body is capable of. “When I first saw the data, I jumped out of my chair,’ said
Asst. Prof Saad Bhamla, a biophysicist at Georgia Tech, Atlanta. Long fascinated by the physics of the finger snap, he looked first at existing research on other ultra-fast movements in the animal world, such as the snapping jaws of termites. These showed that ultra-fast movements tend to rely on a “spring and latching” mechanism, which allows the body to store up energy before quickly releasing it, generating rapid acceleration. In the finger snap, the finger and thumb are pressed together, storing energy in the tendons. Friction between the digits acts as a latch, preventing the release of energy until the finger slips past the thumb, and accelerates into the palm. Using high-speed cameras, Bhamla’s team measured maximum rotational velocities of some 7,800 degrees per second, and rotational accelerations of 1.6 million degrees per second squared – three times the acceleration of the pitcher’s arm. However, when the volunteers wore thimbles or oiled gloves on their fingers, the speed was much reduced. This, said the team, highlights the vital role friction plays in the finger snap. Too little means not enough energy is stored, but too much will lead to energy being dissipated as heat.
Your cat knows where you are
Cats are famously aloof – but they may not be quite as uninterested in their human owners as they seem. A new study has found evidence that the creatures track their owners’ movements, and hold a mental map of where they are. The research involved shutting each cat in a room, and getting its owner to call to it from outside the door; the cats then heard recordings of their owner calling to them, and a stranger doing likewise, from a speaker at the other end of the room. Footage of all this was played to observers who, by noting the cats’ facial movements, judged their reactions to these sounds. They found that the cats seemed surprised only when their owner’s voice suddenly appeared from the other side of the room. “These results suggest that cats hold a mental representation of the unseen owner and map their location from their voice,” the researchers wrote.
Medical file
Obesity levels among young children have risen sharply, after years in which they all but flatlined. In 2020-21, 14% of children were obese at the start of primary school, up from 10% the year before. The four point rise is the biggest rise since the annual study began, 15 years ago. In the last year of primary school, one in four children were obese, up from 21%. Rates were twice as high in the poorest areas. Experts said the lockdowns were likely to have been a “key factor” in the rise.