16 | NewScientist | 14 May 2011

SIX years after NASA’s Gravity Probe B stopped collecting data, the mission has finally found evidence of an effect of general relativity called frame-dragging. But the result comes years after other projects measured the effect to greater precision.

The $750 million mission launched in 2004 to test Einstein’s general theory of relativity by measuring how Earth warps the

fabric of space-time. The warping was expected to slightly alter the spin axis of four gyroscopes in the probe, but the measurements were much noisier than expected, complicating the analysis.

In 2007, the probe’s team reported measuring the dent Earth’s gravity makes in space. But evidence that the Earth drags space around with it as it spins – frame-dragging – was more elusive.

Distracted by too much brain

THOSE who are easily distracted from the task in hand may have “too much brain”.

So says Ryota Kanai at University College London. His team found that people who scored highly on a questionnaire rating distractability had larger than average volumes of grey matter in a brain region called the left superior parietal lobe, or SPL (Journal of Neuroscience, DOI: 10.1523/jneurosci.5864-10.2011).

Why a large left SPL might make someone easily distracted is unclear, but Kanai’s team is testing whether controlling its activity can improve concentration. They have found “some signs” that attention levels can be regulated by using transcranial direct stimulation on the left SPL. This non-invasive technique delivers a tiny electrical current to the area.

Kanai says the technique might one day help people with attention deficit hyperactivity disorder.

Crocodiles swam the Atlantic to reach America

MILLIONS of years before Vikings crossed the Atlantic, crocodiles swam thousands of kilometres from Africa to colonise the Americas.

The finding comes from the most complete evolutionary tree of the genus Crocodylus, featuring all but one of the living crocodile species. Evon Hekkala of Fordham University in New York and colleagues sequenced mitochondrial genomes of all 11 species, eight of which had not had their mitochondrial DNA sequenced before.

This revealed that all four American species are most

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Probe measures swirling space, at last Last week, mission members said in a press conference that they had detected frame-dragging with a precision of 19 per cent. However, laser tracking of the moon’s motion had already reached a precision of 0.1 per cent. Despite this, Francis Everitt of Stanford University in California, who began work on Gravity Probe B about 50 years ago, defends the mission. “The great beauty of it is that we have complementary tests of general relativity,” he says.

closely related to the Nile crocodiles of east Africa, and must have split away roughly 7 million years ago (Molecular Phylogenetics and Evolution, DOI: 10.1016/ j.ympev.2011.03.026), long after Africa and South America began drifting apart 130 million years ago. By 7 million years ago, over 2800 kilometres of ocean lay between the two continents.

Palaeontologists have long suspected that crocodiles swam the Atlantic – they are salt-tolerant, can go up to six months without eating, and females can carry viable sperm for several months after mating – but Hekkala’s finding is “strong evidence in support of that scenario”, says Christopher Brochu of the University of Iowa in Iowa City.

Hekkala says crocodiles may have hitched a ride on the westward-flowing equatorial currents.

SHUFFLING the furniture in care homes can have a positive impact on the behaviour of residents with dementia.

That’s according to Louise Ritchie at the University of Edinburgh, who visited 20 care homes in the UK and found that chairs were often pushed against the walls in lounge areas giving the rooms “no real purpose”.

Simply shifting the furniture in seven care homes so that chairs formed small groups or faced a window led to a 16 per cent increase in active behaviours, such as watching TV. It also led to a 5 per cent rise in social interaction.

Ritchie presented her findings at the British Psychological Society’s annual conference in Glasgow last week.

Help dementia care with chair shuffle

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