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Last updated: April 14, 2012 12:10 am
Predicting a volcanic eruption is hard even in developed countries such as Italy, Iceland and the US, where there is intensive monitoring to detect movements beneath the surface. But the majority of active volcanoes in the developing world, including some that pose a high risk to large populations, have no local monitoring or warning system.
Help is on the way, however, from the sky. Earth-observing satellites, such as the European Space Agency’s Envisat, can detect unrest in unmonitored volcanoes using a technique called Interferometric Synthetic Aperture Radar. InSAR is the most revealing way to show slight deformations in the ground due to movements of molten rock (magma) below.
It works by combining satellite radar images of the same place taken at different times. This is displayed in the form of rainbow-coloured interference patterns or interferograms, in which the arrangement of coloured bands shows the direction and extent of ground deformation.
InSAR is particularly useful for tropical volcanoes, where cloud cover can obscure visual observations, because the radar beam can see through clouds.
As a result, many volcanoes previously thought to be dormant are now known to be showing signs of unrest. The resources for acquiring more detailed, ground-based monitoring can now be targeted at such volcanoes.
A recent review of InSAR technology in the journal Science gave Mount Longonot, Kenya, as an example. Radar data from Envisat showed a 9cm uplift over two years in the volcano, which was previously thought dormant.
Caffeine and other stimulants may improve the performance of poor workers but have the opposite effect on the highly motivated, according to a study at the University of British Columbia.
While InSAR has enormous potential, it is still a new technique that relies on frequent observations and long-duration space missions. A series of Earth-observing satellites called Sentinel, which ESA plans to launch from 2013, is expected to provide the data continuity required for serious InSAR volcano modelling. Sentinel is expected to observe all land masses every six days for the next two decades.
“InSAR is a growing field,” says Juliet Biggs of Bristol University, co-author of the Science paper. “In the past 10 years of my involvement … the community has gone from a small handful of specialists to a wide range of practitioners.”
Of course early warning of eruptions still faces challenges, as scientists try to work out how to tell whether a period of volcanic unrest will lead to eruption. Unrest usually subsides without an eruption – and false alarms can undermine public trust. But consistent InSAR monitoring will give volcanologists a clearer picture of potentially threatening behaviour.
Plant diversity: does your garden measure up?
Which of Earth’s habitats carries the most diverse range of plants?
The answer depends on the scale you’re looking at. For areas of 100 sq m and above, the places richest in plant species are where you might expect: the rainforests of the American tropics. The record number of different plants recorded within one hectare was 942 species in Ecuadorean lowland forest.
But on smaller scales the answer is more surprising, according to an international study in the Journal of Vegetation Science. On all areas below 50 sq m the record count of plant species occurs in temperate grasslands that have long been tended by people.
The world’s richest grasslands are in eastern Europe, from the German border to Romania, and in the Argentine mountains. The Czech part of the White Carpathian Mountains, where grasslands have been managed for livestock farming since Neolithic times, holds the record at five different scales: for example, 43 plant species in a 0.1 sq m patch.
The authors suggest constant disturbance may be the reason why these meadows are so biodiverse. This brings in new plants from outside the area, while regular disruption makes it harder for species to evolve into dominant forms.
Other places famous for their rich plant life – such as the pine savannah and shrub land of south-east America – had less biodiversity than the central American rainforests on larger scales and European meadows on smaller scales.
The study showed a robust mathematical relationship between the size of a plot and the maximum number of species that can grow together there. Applying this mathematical law to the world’s whole land area, they came up with 219,000 species – quite close to the latest estimate of 275,000 for the global total of plant species.
Scientists follow the herd into history
Nearly all of the world’s 1.3 billion cattle are descended from a small herd domesticated 10,500 years ago in what is now modern-day Iran, a new study reports, writes Katherine Rowland.
Researchers from the UK and Europe analysed DNA from the bones of domesticated wild oxen found in archaeological sites that date to soon after the invention of farming. Using computer simulations, the investigators examined variation in the genetic sequences and concluded that the original herd numbered no more than 80. Their findings appear in the Molecular Biology and Evolution journal.
The early ancestors were “very different beasts from modern domestic cattle”, says Joachim Burger, an author based at the University of Mainz, Germany. Without traits such as docility, which have been bred into today’s cattle, the large Neolithic beasts were difficult to capture and breed.
These more intractable qualities, the authors suggest, may explain the small herd size.
While researchers have long known that many animal species were first domesticated in the Levant, it is only with the advent of genetic sequencing tools that scientists can gauge their number.
Jean-Denis Vigne of CNRS in Paris, co-author of the study, said: “Genetic analysis allowed us to answer questions that, until now, archaeologists would not even attempt to address.”
I’ll have the steak ... with packaging
A European consortium is developing a thin edible coating for fresh meat, which could replace the familiar – and wasteful – plastic vacuum packs used widely today.
Nine companies are taking part in the €2m (£1.6m) Meatcoat project, funded mainly by the European Union’s Framework Seven research programme. The group’s UK member is Pepceuticals, a biotech company in Leicestershire, which is making an antimicrobial peptide to include in the coating as a barrier to bacterial infection of the meat.
Peptides are made of amino acids, like the larger protein molecules in meat. They can be made lethal to bacteria but harmless – indeed edible – for people.
“Antimicrobial peptides are widely used in the healthcare sector for tackling infection, so it is a natural progression to apply the same chemistry to food preservation,” says Kamal Badiani, Pepceuticals managing director.
Although meat may still need an outer wrapping, the edible coating would take the place of the plastic that often surrounds individual portions of meat, such as steaks and chicken breasts, in supermarkets. It would be edible, cookable and taste-free.
According to a survey last year, avoidable waste of fresh meat by UK households amounted to 260,000 tonnes a year, a value of about £1.3bn. Antimicrobial coating should prevent the deterioration of meat products and reduce waste of both meat and plastics.
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