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Super-accurate atomic clock doubles up as quantum sim
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THANK climate change for our daily bread. High levels of carbon dioxide in the atmosphere after the last ice age drove us to cultivate wheat. Farming arose in the Fertile Crescent in the Middle East 10,000 years ago. Over the next two millennia, people all over the world took up the practice. This suggests that some global event, such as the spike in atmospheric CO2
Oana Coman-Sipeanu/flickr/getty
seen after the last ice age, triggered this simultaneous development. But why did we domesticate some grain species and not others? To find out, Georg Frenck at the University of Sheffield, UK, grew precursors of today’s wheat and barley that were known to have been eaten by people in the area during the last ice age. One set were exposed to levels of CO2 seen during the last ice age and one to higher levels seen when farming first arose. Four wild grass species that aren’t eaten today, but were found in the area at that time, were also grown. All the plants grew larger under high levels of CO2, but the relatives of wheat and barley grew twice as large and produced double the seeds. This suggests the species are especially sensitive to high levels of CO2, Frenck says, making them the best choice for cultivation after the last ice age. The work was presented at a meeting of the Ecological Society of America in Minneapolis.
Super-accurate clocks double up as quantum simulators THE most accurate timekeepers in the world have a new use. Atomic clocks could be used as simulators for probing quantum mechanics. Behaviour that depends on quantum mechanics, such as that of electrons, is too complex for ordinary computers to simulate. Instead, scientists can physically model electrons using networks of atoms cooled to trillionths of a degree above absolute zero. These atoms are easier to control and, although they are bigger than electrons, are still small enough to follow the laws of quantum
mechanics. However, the low temperatures make them hard to handle. Now Ana Maria Rey and her team from JILA, a lab jointly run by the University of Colorado in Boulder and the US National Institute of Standards and Technology, have stumbled on behaviour in an atomic clock several orders of magnitude warmer that suggests these devices could do the same job. The JILA clock works by tracking the hyper-regular switching of strontium atoms between two
energy levels. In an attempt to increase its signal strength, Rey’s team upped the number of atoms. As it turned out, the quantum interactions between the atoms interfered with the regularity of the transitions, but this also suggested a new use for the clock. Similar, but poorly understood, interactions between electrons are thought to drive magnetic behaviour in solids. So Rey says that tracking the interactions in the atomic clock could shed light on the nature of magnetism (Science, doi.org/nd3). MOHAMMED MAHJOUB/AFP/Getty
Climate change picked our crops
DNA mix-ups hint at how to halt cancer BREAK-UPS are tough, but getting back together can be even harder. When DNA strands get torn, the pieces can drift apart. Cells have a repair system that tries to reconnect the loose ends, but it sometimes goes wrong and DNA from different chromosomes is spliced together. These mix-ups – known as chromosome translocations – can lead to harmful mutations and are a hallmark of cancer cells. But the details of the process are unclear. So Tom Misteli at the National Cancer Institute in Bethesda, Maryland, and colleagues engineered mouse DNA to split when exposed to a yeast enzyme and tagged the break points with fluorescent proteins to make them visible. They then watched thousands of cells repair themselves over 24 hours (Science, doi.org/nd4). They found that an enzyme called DNA-dependent protein kinase plays an important part in correctly reuniting broken strands. Removing this enzyme made a translocation 10 times as likely. The team eventually hopes to find ways to prevent DNA repair going wrong, potentially helping to fight certain cancers.
Camels charged with carrying virus IT’S enough to give a camel the hump. They’re now suspected of carrying the virus behind Middle East respiratory syndrome (MERS). This deadly coronavirus emerged last year in the Arabian peninsula, and has killed 46 of the 94 people it has infected. We know little about where the virus came from or how it spreads. So Marion Koopmans at the National Institute for Public Health and the Environment in Bilthoven, the Netherlands, and colleagues looked at the blood of sheep, cattle, goats and camels in Oman, Spain, the Netherlands and Chile. They found
antibodies to MERS in all of the 50 Omani camels and 15 per cent of the 105 Spanish camels, but not in any of the other samples. This suggests that those camels had been exposed to the virus (The Lancet Infectious Diseases, doi.org/nfb). The discovery was a surprise, says Koopmans. Until now, bats have been the prime suspect, because they harbour similar viruses such as SARS. This is the first real clue to how the virus might spread to humans, says Anthony Mounts of the World Health Organization’s MERS team in Geneva, Switzerland.
17 August 2013 | NewScientist | 17
THANK climate change for our daily bread. High levels of carbon dioxide in the atmosphere after the last ice age drove us to cultivate wheat. Farming arose in the Fertile Crescent in the Middle East 10,000 years ago. Over the next two millennia, people all over the world took up the practice. This suggests that some global event, such as the spike in atmospheric CO2
Oana Coman-Sipeanu/flickr/getty
seen after the last ice age, triggered this simultaneous development. But why did we domesticate some grain species and not others? To find out, Georg Frenck at the University of Sheffield, UK, grew precursors of today’s wheat and barley that were known to have been eaten by people in the area during the last ice age. One set were exposed to levels of CO2 seen during the last ice age and one to higher levels seen when farming first arose. Four wild grass species that aren’t eaten today, but were found in the area at that time, were also grown. All the plants grew larger under high levels of CO2, but the relatives of wheat and barley grew twice as large and produced double the seeds. This suggests the species are especially sensitive to high levels of CO2, Frenck says, making them the best choice for cultivation after the last ice age. The work was presented at a meeting of the Ecological Society of America in Minneapolis.
Super-accurate clocks double up as quantum simulators THE most accurate timekeepers in the world have a new use. Atomic clocks could be used as simulators for probing quantum mechanics. Behaviour that depends on quantum mechanics, such as that of electrons, is too complex for ordinary computers to simulate. Instead, scientists can physically model electrons using networks of atoms cooled to trillionths of a degree above absolute zero. These atoms are easier to control and, although they are bigger than electrons, are still small enough to follow the laws of quantum
mechanics. However, the low temperatures make them hard to handle. Now Ana Maria Rey and her team from JILA, a lab jointly run by the University of Colorado in Boulder and the US National Institute of Standards and Technology, have stumbled on behaviour in an atomic clock several orders of magnitude warmer that suggests these devices could do the same job. The JILA clock works by tracking the hyper-regular switching of strontium atoms between two
energy levels. In an attempt to increase its signal strength, Rey’s team upped the number of atoms. As it turned out, the quantum interactions between the atoms interfered with the regularity of the transitions, but this also suggested a new use for the clock. Similar, but poorly understood, interactions between electrons are thought to drive magnetic behaviour in solids. So Rey says that tracking the interactions in the atomic clock could shed light on the nature of magnetism (Science, doi.org/nd3). MOHAMMED MAHJOUB/AFP/Getty
Climate change picked our crops
DNA mix-ups hint at how to halt cancer BREAK-UPS are tough, but getting back together can be even harder. When DNA strands get torn, the pieces can drift apart. Cells have a repair system that tries to reconnect the loose ends, but it sometimes goes wrong and DNA from different chromosomes is spliced together. These mix-ups – known as chromosome translocations – can lead to harmful mutations and are a hallmark of cancer cells. But the details of the process are unclear. So Tom Misteli at the National Cancer Institute in Bethesda, Maryland, and colleagues engineered mouse DNA to split when exposed to a yeast enzyme and tagged the break points with fluorescent proteins to make them visible. They then watched thousands of cells repair themselves over 24 hours (Science, doi.org/nd4). They found that an enzyme called DNA-dependent protein kinase plays an important part in correctly reuniting broken strands. Removing this enzyme made a translocation 10 times as likely. The team eventually hopes to find ways to prevent DNA repair going wrong, potentially helping to fight certain cancers.
Camels charged with carrying virus IT’S enough to give a camel the hump. They’re now suspected of carrying the virus behind Middle East respiratory syndrome (MERS). This deadly coronavirus emerged last year in the Arabian peninsula, and has killed 46 of the 94 people it has infected. We know little about where the virus came from or how it spreads. So Marion Koopmans at the National Institute for Public Health and the Environment in Bilthoven, the Netherlands, and colleagues looked at the blood of sheep, cattle, goats and camels in Oman, Spain, the Netherlands and Chile. They found
antibodies to MERS in all of the 50 Omani camels and 15 per cent of the 105 Spanish camels, but not in any of the other samples. This suggests that those camels had been exposed to the virus (The Lancet Infectious Diseases, doi.org/nfb). The discovery was a surprise, says Koopmans. Until now, bats have been the prime suspect, because they harbour similar viruses such as SARS. This is the first real clue to how the virus might spread to humans, says Anthony Mounts of the World Health Organization’s MERS team in Geneva, Switzerland.
17 August 2013 | NewScientist | 17