Shell shock

Opaque results or translucent answers?

UNDERSTANDING past climates is crucial to understanding future ones, and few things have been more important to that historical insight than fossil foraminifera. Forams, as they are known, are single-celled marine creatures which grow shells made of calcium carbonate. When their owners die, these shells often sink to the seabed, where they accumulate in sedimentary ooze that often gets transformed into rock.

For climate researchers, forams are doubly valuable. First, regardless of their age, the ratio within them of two stable isotopes of oxygen (¹⁶O and ¹⁸O) indicates what the average temperature was when they were alive. That is because different temperatures cause water molecules containing different oxygen isotopes to evaporate from the sea at different rates; what gets left behind is what shells are formed from. Second, for those forams less than about 40,000 years old, the ratio of an unstable, and therefore radioactive, isotope of carbon (¹⁴C) to that of stable ¹²C indicates when they were alive. That means the rock they are in can be…Continue reading
Source: Economist

Computer says: oops

NOBODY knows how the brain works. But researchers are trying to find out. One of the most eye-catching weapons in their arsenal is functional magnetic-resonance imaging (fMRI). In this, MRI scanners normally employed for diagnosis are used to study volunteers for the purposes of research. By watching people’s brains as they carry out certain tasks, neuroscientists hope to get some idea of which bits of the brain specialise in doing what.

The results look impressive. Thousands of papers have been published, from workmanlike investigations of the role of certain brain regions in, say, recalling directions or reading the emotions of others, to spectacular treatises extolling the use of fMRI to detect lies, to work out what people are dreaming about or even to deduce whether someone truly believes in God.

But the technology has its critics. Many worry that dramatic conclusions are being drawn from small samples (the faff involved in fMRI makes large studies hard). Others fret about over-interpreting the tiny changes the technique picks up. A deliberately provocative paper published in 2009, for example, found apparent activity in the brain of a…Continue reading
Source: Economist

Fast thinking

A GENERAL besieging a city will often cut off its food supply and wait, rather than risking a direct assault. Many doctors dream of taking a similar approach to cancer. Tumours, being rapidly growing tissues, need more food than healthy cells do. Cutting this off thus sounds like a good way to kill the out-of-control cells. But, while logical in theory, this approach has proved challenging in practice—not least because starvation harms patients, too.

In particular, it damages cells called tumour-infiltrating lymphocytes (TILs) that, as their name suggests, are one of the immune system’s main anti-cancer weapons. Valter Longo of the University of Southern California, in Los Angeles, however, thinks he may have a way around this problem. As he and his colleagues write in a paper in this week’s Cancer Cell, they are trying to craft a diet that weakens tumours while simultaneously sneaking vital nutrients to healthy tissues, TILs included.

Dr Longo first used starvation as a weapon against cancer in 2012. In experiments on mice, he employed it in parallel with doxorubicin, a common anticancer drug. The…Continue reading
Source: Economist

Motoring with the Sims

AMERICA’S National Highway Traffic Safety Administration (NHTSA) is investigating the fatal crash in May of a Tesla Model S electric car. Normally such an accident, tragic though it is for the friends and family of the victim, would not warrant a high-level inquiry of this sort. In the case in question, though, the car was operating on Autopilot. That is the name Tesla, an electric-vehicle-maker based in California, has chosen for its “autonomous-driving mode”, in which the vehicle itself, via sensors and computers, lifts from the person behind the wheel much of the burden of controlling the car. According to Tesla, neither the Model S’s driver nor the car’s own sensors noticed a large articulated lorry crossing the road ahead. The car therefore failed to brake, and it ended up careering under the lorry’s trailer. That ripped off its roof, killing the driver.

In the accident, which happened in Florida, the lorry, which was painted white, was set against a brightly lit sky, Tesla noted. One possibility is that the vehicle’s cameras, working in combination with its forward-facing radar, wrongly concluded that the lorry was an overhead sign with…Continue reading
Source: Economist

Flight of fancy

LOOKING to the natural world for engineering inspiration is an idea at least as old as Leonardo da Vinci. Copying nature directly, though, has often proved hard. For example, birds flap their wings to achieve both lift and propulsion, but flying machines that imitate this action have tended not to do well. Human engineering has found it easier to create aircraft by giving them fixed, rigid wings and propelling them with motors.

Air is not the only medium through which animals move by flapping, however. Many creatures flap wings, or wing-like structures, to “fly” through water. That is something human engineers can aspire to imitate because the buoyancy of water provides free lift and its density makes propulsion easier. And, as they write in this week’s Science, a group led by Kit Parker of Harvard University have done just that. They have built a robotic stingray (pictured above) that imitates the motion of its biological counterpart. Moreover, it does so not with the electric circuits and servomotors of conventional robots, but with muscle cells engineered to mimic the elegant undulations of a living…Continue reading
Source: Economist

Autonomous cars put to the test

Source: Economist

A new study finds that mice with genes from three parents live longer

GENETICALLY speaking, everyone has two parents. But that could soon change. Several countries, led by Britain—whose legislators approved the idea last year—are working on a procedure called mitochondrial donation, which would result in a child with DNA from three people: its mother, its father and a female donor sometimes dubbed a mitomum.

The mitomum supplies the child’s mitochondria. These are tiny structures (one is pictured above), present in most cells, that liberate usable energy from food and oxygen. People with defective mitochondria suffer debilitating illness and often die young because the tissues of their bodies are starved of the energy they need to work. Mitochondrial diseases are hereditary, and at the moment incurable. Mitochondrial donation is designed to prevent them by replacing faulty mitochondria with healthy ones.

But mitochondria are, or used to be, creatures in their own right. They are the descendants of ancient bacteria that once lived free, but then entered into a symbiotic union with other cells. As such they have their own tiny genomes, separate from the main genome in the host cell’s nucleus. A baby…Continue reading
Source: Economist

Three’s company

Elixir of life

GENETICALLY speaking, everyone has two parents. But that could soon change. Several countries, led by Britain—whose legislators approved the idea last year—are working on a procedure called mitochondrial donation, which would result in a child with DNA from three people: its mother, its father and a female donor sometimes dubbed a mitomum.

The mitomum supplies the child’s mitochondria. These are tiny structures (one is pictured below), present in most cells, that liberate usable energy from food and oxygen. People with defective mitochondria suffer debilitating illness and often die young because the tissues of their bodies are starved of the energy they need to work. Mitochondrial diseases are hereditary, and at the moment incurable. Mitochondrial donation is designed to prevent them by replacing faulty mitochondria with healthy ones.

But mitochondria are, or used to be, creatures in their own right. They are the descendants of ancient bacteria that once lived free, but then entered into a symbiotic union with other cells. As such they have their own tiny genomes, separate from the main…Continue reading
Source: Economist

A probe to Jupiter has arrived successfully

IT WAS exactly rocket science. In the early hours of Tuesday morning, cruising at a speed of around a quarter of a million kilometres an hour, some 868m km from Earth, and with Jupiter, the solar system’s biggest planet, looming in its cameras, a small space-going robot called Juno began a delicate task. This was to slam on the brakes and slow itself enough to allow it to be captured by Jupiter’s gravity.

Orbital insertions are difficult manoeuvres at the best of times. But Juno was beyond any human help. It had about half an hour to complete its job and, even at the speed of light, messages from the probe back to its masters on Earth would take longer than that to arrive. If anything went wrong it would therefore have to cope on its own.

In the end, everything went flawlessly. Back on Earth, watching humans breathed a sigh of relief: “To know we can go to bed tonight not worrying about what is going to happen tomorrow is just awesome,” said Diane Brown of NASA’s Jet Propulsion Laboratory, which built Juno.

Over the next couple of years, in a series of looping orbits designed to minimise its…Continue reading
Source: Economist

Palaeontology

This photograph is of part of a bird wing preserved in amber from northern Myanmar. It dates from 99m years ago, during the Cretaceous period, and is described in this week’s Nature Communications by Lida Xing of China University of Geosciences, in Beijing, and her colleagues. It is one of two wings, the first known to have been preserved in amber, that her team discovered. Both belonged to juveniles of a group called the Enantiornithes that had claws on their wings (one such is marked with an arrow), probably to help them grip trunks and branches when they climbed trees.

Source: Economist