Science and technologyбез даты Текст источника в новой вкладке

1. A planetary census puts humans in their placeЧт., 24 мая[−]

BILLIONS of years ago a star began to die. In the process, it created something new: 65,500 billion tonnes of carbon that would later be incorporated into the nascent planet Earth. That carbon is still there, and nowadays a fair chunk of it makes up the bodies of living beings. A new study, published this week by Yinon Bar-On and others from the Weizmann Institute of Science, in Israel, provides a comprehensive estimate of how the Earth’s carbon stock is distributed among its inhabitants.

By estimating the amount of carbon stored in organisms, otherwise known as biomass, the scientists were able to compare the relative abundance of different kinds of Earth’s life, weighing both the microbes beneath the soil and the giraffes walking above it on the same scale. The mammals known as human beings like to imagine themselves the lords of the planet. But in terms of raw biomass, the results—published in Proceedings of the National Academy of Sciences—tell a different... Continue reading

2. How stress echoes down the generationsЧт., 24 мая[−]

THE effects of child abuse can last a lifetime. Neglected or abused children have a higher risk of developing all sorts of ailments as adults, including mental illnesses such as depression but also physical ones like cancer and stroke. In fact, the effects may last even longer. Emerging evidence suggests that the consequences of mistreatment in childhood may persist down the generations, affecting a victim’s children or grand-children, even if they have experienced no abuse themselves.

Exactly how this happens is not well understood. Rigorous experiments on human subjects are difficult. Scientists have therefore turned to rats and mice. But now Larry Feig of Tufts University and his colleagues have shown that psychological stress seems to cause similar changes in the sperm of both mice and men. Their study is published this week in Translational Psychiatry.

Biologists know that traits are carried down the generations by genes. Genes encode proteins,... Continue reading

3. Another way to recycle plasticЧт., 24 мая[−]

Dinner is served

PLASTIC production has tripled over the past 25 years, and the mess it causes has risen commensurately. Recycling is one option. Another is biology, and with that in mind researchers have been hunting for creatures that can digest plastics. Several species of fungi and bacteria can do the job, but only slowly. Now Anja Brandon, a student at Stanford University, and her research supervisor, Craig Criddle, have found that bacteria in the guts of mealworms can break down polymers much more quickly.

Other researchers had already found that mealworms can digest a particular plastic called polystyrene. Ms Brandon and Dr Criddle wondered whether polystyrene was uniquely palatable, or whether the bacteria in the worms’ guts might be able to eat other sorts of plastic, too. To check, they turned to polyethylene, which is both more common than polystyrene and very different in chemical terms. If the worms found it nutritious as well, that would suggest... Continue reading

4. Germ-free children may be more prone to leukaemiaЧт., 24 мая[−]

THE long struggle to cure acute lymphoblastic leukaemia (ALL), a childhood blood cancer, is a stand-out tale in the history of medicine. It was a massive endeavour, over decades, with many toxic drugs being tested in different combinations on dying children. It succeeded in the end. Half a century ago, survival rates were less than 0.1%. Today they are about 90%. Yet the cure brings unpleasant side effects, including problems with memory and concentration, and sometimes even other cancers. Globally, rates of ALL seem to be rising by about 1% a year. Yet it is almost non-existent in the poorest countries.

Its causes remain unclear and even controversial. A charity called Children with Cancer UK, for instance, still suggests the disease is connected to electromagnetic radiation from power lines. Into this debate comes Mel Greaves, of the Institute of Cancer Research in London. In a paper in Nature Reviews Cancer, Dr Greaves has marshalled decades of research into ALL... Continue reading

5. Shoemakers bring bespoke footwear to the high streetВт., 22 мая[−]

AMONG the boutiques in the canal district of Amsterdam is a shoe shop, called W-21, that has a selection of stylish footwear in the window. A select group of customers were recently invited there to have their feet scanned by a laser, and then to spend 30 seconds walking on a modified treadmill in a special pair of shoes stuffed with accelerometers, pressure gauges, thermometers and hygrometers. All this generated a wealth of data, which was displayed on a large screen along with a model of how the walker’s feet were moving.

From these data an algorithm determined the ideal soles for the customer’s shoes. Upstairs, a couple of 3D printers began humming away to make those soles. In about two hours they were ready to be fitted to a new pair of shoes, uniquely tailored to each person’s feet.

Some level of customisation is nothing new for buyers of apparel. But there is a big difference between clothes, which are relatively straightforward to tailor and alter, and shoes,... Continue reading

6. Colombia’s national survey of its biodiversity is ambitiousЧт., 17 мая[−]

“BLOODY plants! Always in the way.” That is not the sort of expostulation expected of a researcher from the Royal Botanic Gardens, Kew. But Lee Davies is not a botanist, he is a mycologist—an expert in fungi—who, at home in London, helps curate Kew’s fungarium. And, although history and convenience mean the study of fungi is often lumped together with that of plants, Dr Davies is keen to point out that mushrooms and their kin have nothing in common with the vegetable kingdom beyond their sedentary way of life.

His sentiment was particularly understandable on this occasion. Being ankle deep in mud, on a narrow trail traversing a precipitous hillside that was sloping down who-knew-how-far-or-where, and then trying to collect a specimen hidden just out of reach behind a tangle of greenery, would fray anyone’s nerves. But the specimen was duly acquired, popped in a plastic bag, labelled and carried back to base camp for processing and identification.

Dr Davies and his compadres... Continue reading

7. What makes good music?Чт., 17 мая[−]

HIT songs are big business, so there is an incentive for composers to try to tease out those ingredients that might increase their chances of success. This, however, is hard. Songs are complex mixtures of features. How to analyse them is not obvious and is made more difficult still by the fact that what is popular changes over time. But Natalia Komarova, a mathematician at the University of California, Irvine, thinks she has cracked the problem. As she writes in Royal Society Open Science this week, her computer analysis suggests that the songs currently preferred by consumers are danceable, party-like numbers. Unfortunately, those actually writing songs prefer something else.

Dr Komarova and her colleagues collected information on music released in Britain between 1985 and 2015. They looked in public repositories of music “metadata” that are used by music lovers and are often tapped into by academics. They compared what they found in these repositories with... Continue reading

8. Arctic ice brings an understanding of ancient Europe’s economyЧт., 17 мая[−]

GREENLAND’S icy mountains are not an obvious place to search for an archive of economic history, but a study just published in the Proceedings of the National Academy of Sciences shows that they provide one. Joseph McConnell of the Desert Research Institute, in Reno, Nevada, and his colleagues have tracked economic activity in Europe and the Mediterranean over the centuries by measuring variations in the amount of lead in a core of Greenlandic ice. Lead is a good proxy for economic activity because it is a by-product of silvermaking (lead and silver often occur in the same ore, known as galena), and therefore of the money supply. Extracting silver from galena involves boiling off the lead. Winds from Europe carried to Greenland enough lead pollution from this process for it to be preserved in the layers of snow that, compacted, form the island’s ice cap.

Although the lead concentration in the core that Dr McConnell looked at shows many peaks and troughs, some... Continue reading

9. The two ways to measure how fast the universe is growing do not agreeЧт., 17 мая[−]

Edwin Hubble in his natural habitat

ONE of the most basic facts about the universe is that it is expanding. This observation, made by Edwin Hubble (pictured) in 1929, leads to all sorts of mind-stretching ideas. That the universe is growing implies it was smaller in the past—possibly a lot smaller. Which leads to the thought that a “Big Bang” kicked everything off. It also opens the question of whether the universe will expand for ever, or will eventually see its expansion halted and reversed by gravity, thus ending in a Big Crunch.

Things got stranger in 1998, when a group of astrophysicists discovered that the rate of expansion is increasing, for this finding raised another question in turn. The acceleration of the expansion was so great that it seemed something was actively pushing the universe apart. Thus was born the notion of “dark energy”—a new component of the cosmos, invoked to balance the equations.

Trying to work out what dark energy... Continue reading

10. The world’s lightest wireless flying machine lifts offВт., 15 мая[−]

Where’s the swatter?

DRONES are getting ever smaller. The latest is the first insect-sized robot to take to the air without a tether delivering its power.

To get their device aloft, Sawyer Fuller of the University of Washington, in Seattle, and his colleagues, who will be presenting their work at the International Conference on Robotics and Automation in Brisbane later this month, had to overcome three obstacles. One is that the propellers and rotors used to lift conventional aircraft are not effective at small scales, where the viscosity of air is a problem. A second is that making circuitry and motors light enough for a robot to get airborne is hard. The third is that even the best existing batteries are too heavy to power such devices. Nature’s portable power supply, fat, packs some 20 times more energy per gram than a battery can.

In 2013 Dr Fuller, then at Harvard, was part of a team which overcame the first of these hurdles, making a robotic insect that weighed just 80mg. The team copied nature by equipping their device with a pair of wings which flapped 120 times a second (close to the frequency of a fly’s wing beat). They partly overcame the second hurdle by doing away with conventional motors and driving the wings using a piezoelectric ceramic that flexes in response to electrical... Continue reading

11. How do you define “safe driving” in terms a machine can understand?Чт., 10 мая[−]

WHEN people learn to drive, they subconsciously absorb what are colloquially known as the “rules of the road”. When is it safe to go around a double-parked vehicle? When pulling out of a side street into traffic, what is the smallest gap you should try to fit into, and how much should oncoming traffic be expected to brake? The rules, of course, are no such thing: they are ambiguous, open to interpretation and rely heavily on common sense. The rules can be broken in an emergency, or to avoid an accident. As a result, when accidents happen, it is not always clear who is at fault.

All this poses a big problem for people building autonomous vehicles (AVs). They want such vehicles to be able to share the roads smoothly with human drivers and to behave in predictable ways. Above all they want everyone to be safe. That means formalising the rules of the road in a precise way that machines can understand. The problem, says Karl Iagnemma of nuTonomy, an AV firm that was spun out of the Massachusetts... Continue reading

12. A better way to transmit messages underwaterЧт., 10 мая[−]

RADIO waves cannot penetrate water, so cannot be used for submarine communication. That is why the sea is probed by sonar, not radar. But, as people and their machines venture ever farther into the deep, ways of building underwater communications networks would be welcome. And researchers at Newcastle University, in England, led by Jeff Neasham, think they have just the thing to build them with: an acoustic “nanomodem”.

Existing underwater modems, which transmit and receive data via sound, are power-hungry (consuming up to two watts when receiving messages, and as much as 35W when transmitting) and expensive (costing between ?5,000 and ?15,000, or $7,000-20,000). Dr Neasham’s nanomodems consume only ten milliwatts when listening, and 1W when broadcasting. They cost about ?50 a pop. They are also, being about the size of a matchbox, a tenth as big and heavy as the conventional variety. But they suffer from no diminution in range. They are able, as an existing modem is, to broadcast... Continue reading

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