Waste not, want not

Is that ammonia I sniff?

AMMONIA is as repulsive to most marine animals as it is to land-lubbing ones—and for good reason. It is extremely toxic. But there is an exception. Far from being repelled by ammonia, sharks are actually attracted to it. The longtime assumption has been that this is because it is a waste product, voided into the water by fish and other creatures, that signals the presence of potential prey. But Chris Wood and Marina Giacomin of the University of British Columbia, in Vancouver, think there may be more to it than this. As they describe in the Journal of Experimental Biology, they suspect that for sharks, ammonia is itself a useful resource.

All animals make ammonia. It is a compound of nitrogen and hydrogen produced by the breakdown of amino acids, the building blocks of proteins. Marine creatures can flush it directly into the sea (fish do so through their gills), since it is soluble in water. Land animals often add carbon and oxygen to convert it into urea, which is far less toxic, and store the result in solution in a bladder, for periodic evacuation. Sea creatures can make…Continue reading
Source: Economist

In an octopus’s garden

THREE billion dollars sounds a lot to spend on a map. But if it is a map of two-thirds of Earth’s surface, then the cost per square kilometre, about $8.30, is not, perhaps, too bad. And making such a map at such a cost is just what an organisation called the General Bathymetric Chart of the Oceans (GEBCO) is proposing to do. GEBCO, based in Monaco, has been around since 1903. Its remit, as its name suggests, is to chart the seabed completely. Until now, it has managed less than a fifth of that task in detail. But means of mapping the depths have improved by leaps and bounds over recent decades. So, with the aid of the Nippon Foundation, a large, Japanese philanthropic outfit, GEBCO now proposes to do the job properly. It plans to complete its mission by 2030.

The area of Earth’s ocean is two and a half times the area of Mars—and it is often claimed that Mars’s surface is the better recorded of the two. It took mere hours to find the crash site of Schiaparelli, an ill-fated Mars-bound space craft (see <a…Continue reading
Source: Economist

First, treat the parents

AUTISM may bring a lifetime of disability and difficulty to the most severely afflicted. As children, they often struggle to communicate, are anxious in situations unproblematic for anyone else and may behave in repetitive ways that disturb others. As adults, they may be shunned—or even ostracised.

Medical science has little to offer. Drugs have limited effects, and although there have been claims for many years that therapies aimed at training a child directly to behave in desirable ways (known as behavioural intervention) can work, the evidence they actually do so is poor. All this, observes Tony Charman, a clinical psychologist at King’s College, London, leaves parents of autistic children vulnerable to false promises. Only this month, for example, a four-year-old boy had to be taken to hospital in Britain after being subjected to a bizarre array of treatments described as “holistic medicine”.

Incidences of such quackery should be reduced by a study published in this week’s Lancet by Dr Charman and his colleagues. The “Pre-school Autism Communication Trial” (PACT) attempted to answer, once and for…Continue reading
Source: Economist

Topsy turvy

Afar horizon

STUDYING the seabed does not always mean penetrating the sea itself, even if that penetration is done using sound waves rather than submarines (see article). There are a few places where what a geologist would call the ocean floor is actually dry land. One such is the Danakil depression, which lies near the northern vertex of the Afar Triangle, a rift valley stretching from the Dallol volcano in Ethiopia past the salt plains of Lake Assal, in Djibouti, to the north-west tip of Somalia, and then inland to Awash. Millions of years ago, the Danakil was indeed covered by the sea—in its case, the Red Sea. But volcanic eruptions formed barriers of lava that isolated it from the ocean. What water remained evaporated in the intense heat, leaving brine lakes and saline flats. These are mined, and the resulting slabs of salt exported by camel, by nomadic Afars who are the nearest thing the depression has to permanent inhabitants.

Dallol, appropriately, means disintegration in Afar….Continue reading
Source: Economist

Crash testing

“SOMEONE is learning how to take down the internet.” This was the headline of a blog post Bruce Schneier, a noted cyber-security expert, wrote in mid-September. It looked prescient when, on October 21st, Dynamic Network Services (Dyn), a firm that is part of the internet-address system, was disrupted by what is called a “distributed denial of service” (DDoS) attack. (Essentially, a DDoS floods servers with requests until they can no longer cope.) For hours, hundreds of sites were hard to reach, including those of Netflix, PayPal and Twitter.

The attack on Dyn was only the latest in a string of similar ones. On September 20th, for instance, the victim was Brian Krebs, an American journalist who often reports on internet criminals. The server where he hosts his blog became the target of one of the largest DDoS attacks on record (it was bombarded with data equivalent to almost half a percent of the internet’s entire capacity). Most of the other recent digital assaults, however, were more discerning—as if the attacker “were looking for the exact point of failure,” Mr Schneier wrote in his blog post.

It is not clear who the…Continue reading
Source: Economist

Growing anti-malaria drugs in tobacco plants

ONE of the most valuable weapons in the war on malaria is artemisinin, a drug derived from the leaves of sweet wormwood. Its discovery, inspired by wormwood’s use as a herbal remedy for the disease, brought Tu Youyou, the scientist responsible for making it, the first Nobel prize for medicine awarded to a researcher working in China. Artemisinin has, though, proved stubbornly difficult to synthesise chemically, meaning that extract-of-wormwood is still the main source of supply. That is a problem, for wormwood plants take between 190 and 240 days to mature. Moreover, yields are not huge—a mere half a milligram per gram of dried wormwood leaves. Alternative sources would thus be welcome.

One is to engineer relevant genes into yeast cells. That works, but only up to a point. The commercial process based on this method turns out artemisinic acid, not artemisinin. Further chemical treatment is needed to produce the drug, and the end product has had difficulty competing with artemisinin derived from plants. However, Shashi Kumar of the International Centre for Genetic Engineering and Biotechnology, in New Delhi, is proposing a different approach,…Continue reading
Source: Economist

Sexual cannibalism in spiders

Gone fishin’

ANIMAL mating can be a cruel and unusual process. Male bedbugs inseminate females by piercing their bellies and depositing sperm inside their paramours’ body cavities. Male chimpanzees and lions kill the suckling infants of females before mating with them, as this brings those females more rapidly into oestrus. Male dolphins routinely engage in rape. Nor are aggressive mating practices perpetrated solely by males against females. In many species of insects and spiders, females eat their partners after sex.

Such cannibalism clearly brings advantage to the female, who gets an easy snack. But the benefits (if any) for the male are less obvious. That there might sometimes be such benefits, though, is an idea that intrigues zoologists—and so, from time to time, some of them look into the matter.

The latest to do so are Steven Schwartz of Gonzaga University, in the American state of Washington, and Eileen Hebets of the University of Nebraska-Lincoln. Dr Schwartz and Dr Hebets note that, after mating, the males of one species of arachnid, the dark fishing spider, spontaneously die and thus ensure…Continue reading
Source: Economist

Listen to the music of the traffic in the city

Like the Rockefeller Centre, but different

THE Rockefeller Centre sprawls across 89,000 square metres of midtown Manhattan. Curiously, Alcatraz, in San Francisco Bay, the island home of America’s most famous former prison (see picture), has exactly the same area. That coincidence aside, few might imagine the manicured roof gardens and art deco office buildings of the one have much in common with the brutal crags and blockhouses of the other. But they do. For research by Claudio Silva of New York University and his colleagues suggests that the two have a striking resemblance when it comes to the daily ebb and flow of tourists, as judged from the level of activity on Flickr, a photo-hosting site. Dr Silva thinks the peaks and troughs of Flickr activity that his research has discovered in this and other cases are a measure of an area’s “urban pulse”. If so, the Rockefeller Centre and Alcatraz share a pulse.

On October 25th, at a meeting of the Institute of Electrical and Electronics Engineers in Baltimore, Dr Silva plans to present the idea that, like real pulses, urban pulses have useful diagnostic and prognostic…Continue reading
Source: Economist

Triumph or disaster?

THAT space flight is as much show business as science was confirmed on the evening of October 19th, when members of the ExoMars team put on the bravest of faces for a broadcast from their mission control in Darmstadt, Germany, about the arrival of the project’s craft at Mars. ExoMars is a joint endeavour by Europe’s and Russia’s space agencies. If science were its only criterion, team members would have been cock-a-hoop. Their main research vehicle, the Trace Gas Orbiter (TGO), had successfully entered almost precisely its designated orbit around Mars, and looked well placed to do its job of mapping concentrations of the minor chemical components of the Martian atmosphere, which is composed mostly of carbon dioxide. This is an important task, for one such component is methane—and that may be a sign the planet harbours life.

Instead, there were the flat, controlled voices of those trying to come to terms with disappointment, while hoping against hope that their worst fears are wrong. The reason was that the other part of the mission, a cone-shaped landing craft called Schiaparelli, had abruptly gone silent on its way…Continue reading
Source: Economist

Prospects for new life

Source: Economist