Fears that California’s huge Oroville Dam will fail have subsided—for now

FOR the past five years, drought-stricken Californians have implored the heavens for rain. Lately, their prayers have been answered more torrentially than many may have wished. This winter is shaping up to be California’s wettest on record. The snowpack on the Sierra Nevada (a crucial water supply for the long, dry summer) is almost double its normal depth, and near-empty reservoirs are filling fast to the brim. To many farmers and residents, the peripatetic visitor from the tropics responsible for their dousing—an “atmospheric river” (known colloquially as the Pineapple Express) that is hundreds of miles wide and carries more moisture than the Amazon—has outstayed its welcome.

None may wish an end to the deluge more than the good people living downstream of the Oroville Dam, 75 miles (120km) north of Sacramento, which came close to failing catastrophically on February 12th. Some 188,000 people in communities along the Feather River below the dam were given notice to evacuate, as engineers worked feverishly to prevent an uncontrolled release of water from the 770-ft (235m) high dam—the highest in America.

With yet more storms on…Continue reading
Source: Economist

Certain bacteria protect against a disease that is a growing threat

A bit of muck might have helped

CAN you be too clean? That is the question posed by the hygiene hypothesis, which seeks to explain why, as many illnesses have become rarer in rich countries, some have become more common. The hygiene hypothesis posits that the rise of several of these diseases, including asthma, eczema and type-1 diabetes (all of which seem associated with malfunctions of the immune system), has been caused by improvements in hygiene of the sort that have helped get rid of other illnesses. Exactly how that might happen is unclear. But at the AAAS meeting Brett Finlay of the University of British Columbia, in Vancouver, persuasively filled in some of the blanks in the case of asthma.

Asthma is caused by chronic inflammation of the airways, and inflammation is an immune response. The thinking behind the hygiene hypothesis is that a lack of exposure to parasites and pathogens in what has become an unnaturally clean environment means a child’s immune system does not develop appropriately. Evidence that asthma is a consequence of overcleanliness includes the facts that farm-raised children are less prone to it than…Continue reading
Source: Economist

Plucking minerals from the seabed is back on the agenda

Crunch time for submarine mining

IN THE 1960s and 1970s, amid worries about dwindling natural resources, several big companies looked into the idea of mining the ocean floor. They proved the principle by collecting hundreds of tonnes of manganese nodules—potato-sized mineral agglomerations that litter vast tracts of Davy Jones’s locker. At first sight, these nodules are attractive targets for mining because, besides manganese, they are rich in cobalt, copper and nickel. As a commercial proposition, though, the idea never caught on. Working underwater proved too expensive and prospectors discovered new mines on dry land. Worries about shortages went away, and ocean mining returned whence it had come, to the pages of science-fiction novels.

Now it is back. As Mark Hannington of the GEOMAR-Helmholtz Centre for Ocean Research, in Germany, explained to the AAAS, prototype mining machines are already being tested, exploration rights divvied up between interested parties, and the legal framework put in place. Next week the International Seabed Authority, which looks after those parts of the ocean floor beyond coastal countries’…Continue reading
Source: Economist

How to predict and prepare for space weather

SOMETIMES the sun burps. It flings off mighty arcs of hot plasma known as coronal mass ejections (CMEs). If one of these hits Earth it plays havoc with the planet’s magnetic field. Such storms are among the most spectacular examples of what astronomers call space weather, a subject to which a session at this year’s meeting of the American Association for the Advancement of Science (AAAS), in Boston, was devoted. A big CME can have profound effects. In 1859, for instance, a CME subsequently dubbed the Carrington event, after a British astronomer who realised its connection with a powerful solar flare he had observed a few days earlier, generated auroras that could be seen in the tropics. Normally, as the names “northern” and “southern” lights suggest, such auroras (pictured above) are visible only from high latitude. More significant, the Carrington event played havoc with Earth’s new telecommunications system, the electric telegraph. Lines and networks failed, and some operators received severe shocks. 

Today, the damage would be worse. A study published in 2013 by Lloyd’s, a London insurance market, estimated that a Carrington-like…Continue reading
Source: Economist

America’s first immigrants had to wait 8,000 years to be admitted

HOW America was originally colonised is a topic of perennial interest at the AAAS. Until recently, the earliest uncontested archaeological evidence of people living in the New World came from Swan Point, in Alaska. This dates back 14,400 years. Linguists, however, maintain that the diversity of native languages in the Americas could not have arisen so quickly. Conventional models of linguistic evolution assume tongues separate in the way populations of organisms do—so that the flow of vowels, words and grammatical structures between groups must cease before new languages can emerge, just as a cessation of gene flow gives rise to new species. This suggests it would take at least 50,000 years for a single population speaking a single language to diversify and spread through the Americas in a way that yielded the pattern heard today. Since Native Americans’ genes do, indeed, indicate they all derive from a single population, this discrepancy in timing is a paradox.

That paradox may be close to resolution. Recent digs have pushed the physical evidence of America’s settlement back in time. Meanwhile, as the meeting heard from Mark Sicoli, a linguist…Continue reading
Source: Economist

How to use mosquitoes to combat disease

Gotcha

IMAGINE a small drone that could fly around sampling animals and people in an effort to see which pathogens are present in an area, and what host species harbour them. That would be invaluable to epidemiologists seeking to understand how diseases spread, and how to predict and pre-empt their outbreaks. At the moment, such a drone is beyond human technology. But this may not matter, because nature has already come up with one. It is called the mosquito.

Mosquitoes (female mosquitoes, at any rate) draw blood from animals to feed on. While doing so, they also ingest any blood-born pathogens present in those animals. What a splendid idea, thought Ethan Jackson and Jonathan Carlson, of Microsoft Research in Seattle, to design a system that captures mosquitoes so that the pathogens they have ingested can be studied. Thus, as Dr Jackson explained to the AAAS meeting, was Project Premonition born.

The core of the project is a portable mosquito trap. The current version of this is a cylinder about 35cm high, with 64 cells the size of matchboxes arranged around its exterior. Each of these cells has a door that springs…Continue reading
Source: Economist

Oceans of pollutants

Source: Economist

How to stop fertiliser being washed away by the rain

Spreading growth

IN MEDIEVAL England peasants were permitted to graze their sheep on the lands of the nobility. There were no restrictions on how much their livestock could feed, but there was one ironclad rule: the peasants were not allowed to collect their animals’ droppings. Though the English nobles who came up with such regulations could not have known that the excrement was rich in nitrogen and vital for plant growth, they clearly knew that lands denied faeces were less productive. Today most farmers rely on synthetic fertilisers to do the nitrogen-enhancing job once reserved for dung. Urea, a compound of nitrogen, hydrogen, carbon and oxygen, can be made cheaply by mixing ammonia and carbon dioxide together at high pressure. The result is turned into pellets that can be scattered easily over fields.

Unfortunately, when such pellets are exposed to heavy rain, the urea they contain is quickly and wastefully washed away. A method of keeping it in place would thus be welcome. And Nilwala Kottegoda of the Sri Lanka Institute of Nanotechnology thinks she has one. As she and her team report in <em…Continue reading
Source: Economist

Pedestrians and robots will soon share the pavements

WHO would be a delivery driver? As if a brutal schedule, grumpy motorists, lurking traffic wardens and the risk of an aching back were not bad enough, they now face the fear of robots taking their jobs. Though the buzzing, parcel-carrying aerial drones planned by the likes of Amazon and Google get most of the press, a more serious threat may come from a new breed of ’droids that are about to take to the world’s pavements. 

The latest, called Gita, was unveiled earlier this month by Piaggio Fast Forward, a subsidiary of Piaggio, an Italian firm that is best known for making Vespa motor scooters. Gita’s luggage compartment is a squat, drumlike cylinder that has been turned on its side. This, as the picture above shows, is fitted with two wheels of slightly larger diameter than the drum. These let the whole thing roll smoothly along, keeping the luggage compartment upright, at up to 35kph (22mph). Normally, though, Gita does not travel anything like that fast. Instead, it follows at walking pace a metre or two behind its human owner—or, more accurately, an electronic belt that the owner wears. A wireless connection to a stereoscopic camera…Continue reading
Source: Economist

The cause of nodding syndrome

NODDING syndrome is a form of epilepsy that strikes children, mostly between the ages of five and 15. Despite the innocuous name, it is debilitating. It robs its victims of their mental capacity, stunts their growth and causes both the characteristic “nodding-off” motion which gives its name and more serious seizures, often when a child is being fed. The exact death rate is unknown, but it is high.

The syndrome is also something of a medical mystery. The first cases were identified in Tanzania in the 1960s. Now it has spread to parts of Uganda and South Sudan. No one knows how many people are affected, but it is thousands, at least. Nor has anyone been sure what causes the disease. But Tory Johnson, of America’s National Institutes of Health, and her colleagues have a theory. As they describe in a paper just published in Science Translational Medicine, they suspect that nodding syndrome is an “autoimmune” disease caused by sufferers’ attempts to fight off infection by a parasitic worm.

The worm in question is Onchocerca volvulus, a tiny nematode spread by the bites of…Continue reading
Source: Economist