Page 19 - downmagaz.com

IN BRIEF

IMAGEBROKER/ALAMY STOCK PHOTO Pretty birds just

can’t carry a tune

A MALE peacock’s call isn’t an
appealing noise, but its splendid
tail means that doesn’t matter.
Now an analysis shows that this
is a common trade-off in birds:
the best lookers aren’t the greatest
singers, while the best vocalists
aren’t as easy on the eye.
Christopher Cooney at the
University of Oxford and his
colleagues studied the songs
of 518 bird species and their
feather colours. In particular,
they looked at how feathers
differed between males and
females of each species – a sign
that plumage colour evolved to
help attract a mate.
They found that birds in which
one sex has showier plumage
than the other tend to have more
monotonous songs. For species
in which the males and females
more closely resemble each other,
Secret of the mantis shrimp’s like a bow, and when it is released, that energy transfers the males sing longer songs and
into the club. use more notes (Proceedings of the
mighty punch are revealed Miserez and his colleagues found the saddle can hold Royal Society B, doi.org/cvwk).
all that energy without snapping because of its two-layer
THE mantis shrimp packs a mean punch, smashing its structure. The top is made of a ceramic material similar
victims’ shells with the force of a .22 calibre bullet. to bone and the bottom mostly plastic-like biopolymers. A condom that
Now we know how it does this. It isn’t because it has When the saddle is bent, the top layer is compressed
particularly powerful muscles – instead of big biceps, and the bottom is stretched. The ceramic can hold a lot of can self-lubricate
it has arms that are naturally spring-loaded, allowing it energy when compressed, but is brittle when bent and
to swing its fist-like clubs at up to 23 metres per second. stretched. The biopolymers are stronger and stretchier, THE next generation of condoms
The key to the shrimp’s punch is a previously so hold the whole thing together (iScience, doi.org/cvxr). may lubricate itself with a polymer
identified saddle-shaped structure on the arm just Materials designed using our knowledge of these coating that turns slippery once
above its club. It works a bit like a bow and arrow, shrimp shapes may be useful in microrobots, says Ming it comes into contact with body
says Ali Miserez at Nanyang Technological University Dao at the Massachusetts Institute of Technology. fluids, and that doesn’t dry out.
in Singapore. The muscles pull on the saddle to bend it See Letters for more on the power of the shrimp’s punch Most condoms are coated with
silicone oil. But this, and other
lubricants based on water, oil or
The trick that makes our brains superior This could give greater silicone, are absorbed by the skin,
computing powers to each cell. so lubrication wears off.
EACH of our brain cells could work of their tree-like structure. Mark In a mouse neuron, if a signal Mark Grinstaff at Boston
like a mini-computer, according Harnett at the Massachusetts starts down a dendrite, there are University and his colleagues have
to recordings of electrical activity Institute of Technology and his so many ion channels that the tackled the problem by treating
in the fine branches of the cells. team have now used thinner signal will probably continue into condoms with a “water-loving”
The work has revealed a key electrodes to record activity in the main trunk of the neuron. In coating called HEA/BP/PVP. This
difference between human and dendrites, fine branches at the a human neuron, by contrast, the turns slippery on meeting water
mouse brain cells, or neurons, end of the trunk. set-up allows patterns of activity and body fluids and won’t wear
that could help explain our Compared with mice, in dendrites, and in synapses off. Grinstaff says the coating has
superior intelligence. human dendrites have fewer ion linked to dendrites, to determine been used to lubricate medical
Signals within human neurons channels: the molecules in the the final “decision” on whether devices, but will need approval for
have been recorded before, brain cell’s membrane that let the main branch of a brain cell condom use (Royal Society Open
but always in the main “trunk” electricity flow along the dendrite. should fire (Cell, doi.org/cvwp). Science, doi.org/cvwm).

27 October 2018 | NewScientist | 17