A new Russian weapon may give it an underwater advantage

WHEN introduced 40 years ago, the Soviet Shkval (“Squall”) torpedo was hailed as an “aircraft-carrier killer” because its speed, more than 370kph (200 knots), was four times that of any American rival. The claim was premature. Problems with its design meant Shkval turned out to be less threatening than hoped (or, from a NATO point of view, less dangerous than feared), even though it is still made and deployed. But supercavitation, the principle upon which its speed depends, has continued to intrigue torpedo designers. Now, noises coming out of the Soviet Union’s successor, Russia, are leading some in the West to worry that the country’s engineers have cracked it.

Life in a bubble

Bubbles of vapour (ie, cavities) form in water wherever there is low pressure, such as on the trailing edges of propeller blades. For engineers, this is usually a problem. In the case of propellers, the cavities erode the blades’ substance. Shkval’s designers, however, sought, by amplifying the phenomenon, to make use of it. They gave their weapon a blunt nose fitted with a flat disc (pictured above) that creates a circular trailing edge…Continue reading
Source: Economist

The automation game

Source: Economist

Two strange mammals illuminate the process of natural selection

CONVERGENT evolution—different species arriving independently at the same answer to a question posed by nature—is a topic of great interest to biologists. One aspect of the phenomenon which has not yet been much looked at, however, is its underlying genetics. In particular, an issue not previously addressed is how often such changes arise from similar mutations in the two convergent lines, and how often they have different genetic causes that happen to have similar effects on the animals’ forms and functions. That situation has now changed, with an examination of two creatures which, though only distantly related, share an unusual feeding habit, an unusual anatomical feature and an unusual name: panda.

The giant panda is a black and white bear. The red panda is related to weasels, raccoons and skunks. Their habitats—mountainous areas of southern China and its neighbours—overlap, but their last common ancestor lived 43m years ago. They do, though, share a limited kinship, for both are members (along with dogs, cats, hyenas, mongooses, seals and so on) of the mammalian order Carnivora. Which is curious, because both are…Continue reading
Source: Economist

The ultimate angling aid: a fishing drone

MOST pastimes nowadays involve lots of high-tech gadgets. For fishermen these range from electronic bite alarms to carbon-fibre rods, specialised clothing and tackle boxes stuffed with various odd and ends. There is so much clobber that some anglers use trolleys to lug around their gear. Now the ultimate piece of kit has arrived: a fishing drone.

The device, called PowerRay, comes from PowerVision, a dronemaker in Beijing. It is a submersible that carries a video camera to send images of Neptune’s kingdom back to the angler on the bank or boat above. These pictures, either still or video, can be viewed on the screen of the hand-held unit that controls the drone, or on a smartphone. Those who really want to get into the swim can don a pair of virtual-reality goggles to watch them.

PowerRay is equipped with a fish detector. This uses sonar, sending out sound waves and picking up the reflections that bounce off nearby objects. PowerVision claims that the system can distinguish between species, permitting the angler to identify the target he wants. The drone can then be used to carry a baited hook to the spot, and let it go. Just for good…Continue reading
Source: Economist

A “new” star should appear in 2022

X marks the spot

AMATEUR astronomers have a new date for their diaries. In 2022, in the constellation of Cygnus, they will be treated to the sight of a nova, or “new star”. By themselves, novas are not particularly noteworthy. Several dozen a year happen in Earth’s home galaxy, the Milky Way, alone. But this one will be special for two reasons.

One is its intensity: provided you are somewhere reasonably dark (in the countryside, in other words, rather than a big city) it will be bright enough to be seen by the naked eye. The second is that it will be the first nova whose existence was predicted before the fact. Assuming everything goes according to schedule, the credit for that will belong to Lawrence Molnar, an astronomer at Calvin College, in Michigan, and his team, who have set out their predictions in a paper to be published soon in the Astrophysical Journal.

It is a tale of scientific serendipity. “Nova”, which is Latin for “new”, comes from the title of a book (also the title of this article) published in 1573 by Tycho Brahe, a Danish astronomer. This recorded what would…Continue reading
Source: Economist

Electricity now flows across continents, courtesy of direct current

THE winds of the Oklahoma panhandle have a bad reputation. In the 1930s they whipped its over-tilled topsoil up into the billowing black blizzards of the Dust Bowl. The winds drove people, Steinbeck’s dispossessed, away from their livelihoods and west, to California.

Today, the panhandle’s steady winds are a force for creation, not destruction. Wind turbines can generate electricity from them at rock-bottom prices. Unfortunately, the local electrical grid does not serve enough people to match this potential supply. The towns and cities which could use it are far away.

So Oklahoma’s wind electricity is to be exported. Later this year, lawsuits permitting, work will begin on a special cable, 1,100km (700 miles) long, between the panhandle and the western tip of Tennessee. There, it will connect with the Tennessee Valley Authority and its 9m electricity customers. The Plains and Eastern Line, as it is to be known, will carry 4,000MW. That is almost enough electricity to power Greater London. It will do so using direct current (DC), rather than the alternating current (AC) that electricity grids usually employ. And it will run…Continue reading
Source: Economist

Intergenerational conflict may explain the menopause

Hurry up, Grandma

THE menopause is a puzzle. Why do women, unlike most female mammals, stop reproducing decades before they die? Analysing birth and death records shows that the assistance they give in bringing up grandchildren does have a measurable effect on those grandchildren’s survival. But that does not prove such assistance is more valuable in evolutionary terms than continued fertility would be.

Two other mammals undergo a menopause, however. These are killer whales and short-finned pilot whales. And a long-term analysis of killer-whale populations, by Darren Croft of the University of Exeter, in England, and his colleagues, just published in Current Biology, suggests the missing part of the explanation may be that the menopause not only frees a female to help raise the grandoffspring, but also reduces competition between her and her gravid and nursing daughters.

Dr Croft’s killer whales swim off the coasts of British Columbia, in Canada, and its southern neighbour, the American state of Washington. They have been monitored by marine biologists every year since 1973. They live in…Continue reading
Source: Economist

Conversational computers

Source: Economist

A cardboard centrifuge separates blood cells from plasma

TAKE a cardboard disc and punch two holes in it, close to, and on either side of, its centre. Thread a piece of string through each hole. Now, pull on each end of the strings and the disc will spin frenetically—first in one direction as the strings wind around each other, and then in the other, as they unwind.

Versions of this simple children’s whirligig have been found in archaeological digs on sites across the world, from the Indus Valley to the Americas, with the oldest examples dating back to 3,300BC. Now Manu Prakash and his colleagues at Stanford University have, with a few nifty modifications, turned the toy into a cheap, lightweight medical centrifuge. They report their work this week in Nature Biomedical Engineering.

Centrifuges’ many uses include the separation of medical samples (of blood, urine, sputum and stool) for analysis. Tests to spot HIV, malaria and tuberculosis, in particular, require samples to be spun to clear them of cellular debris. Commercial centrifuges, however, are heavy and require power to run. That makes them impractical…Continue reading
Source: Economist

How reptilian were dinosaur eggs?

A dinosaur’s nest

DID dinosaur eggs hatch quickly, like those of birds (which are dinosaurs’ direct descendants), or slowly, like those of modern reptiles (which are dinosaurs’ collateral cousins)? That is the question addressed by Gregory Erickson of Florida State University and his colleagues in a paper just published in the Proceedings of the National Academy of Sciences. It is pertinent because it touches on the wider matter of just how “reptilian” the dinosaurs actually were. Researchers already know that many were warm-blooded, and that some had insulation in the form of feathers, even though they could not fly. Fast-developing embryos would drive a further wedge between them and their truly reptilian kin.

To investigate, Dr Erickson looked at two sets of fossilised dinosaur eggs. The first, from a Mongolian nest (pictured), was laid by Protoceratops andrewsi, a sheep-sized creature that lived 70m years ago. The second, from Canada, was laid by Hypacrosaurus stebingeri—a species contemporary with P. andrewsi that…Continue reading
Source: Economist