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16 | NewScientist | 22 January 2011 HERE’S another reason to kick the habit: within minutes of inhaling, regular smokers produce chemicals that cause genetic damage linked with cancer. Polycyclic aromatic hydrocarbons (PAHs) present in tobacco smoke are one of the main culprits behind lung cancer. In the body they form metabolites that react readily with DNA to produce mutations that in turn can cause tumours. Stephen Hecht and colleagues at the University of Minnesota in Minneapolis asked 12 volunteers with a history of smoking to smoke a cigarette laced with phenanthrene, a type of PAH that binds with DNA but is non-carcinogenic. By collecting blood samples before, during and after smoking, the team were able to track the Car batteries run on relativity YOU’VE got relativity to thank every time your car starts. The transfer of electrons during a chemical reaction in lead-acid car batteries produces a potential of more than 2 volts. Yet for tin, which sits just above lead in the periodic table, a similar reaction is too feeble to power a battery. Now Pekka Pyykkö at the University of Helsinki in Finland and colleagues calculate that the difference is mainly due to relativity. Electrons whiz around the heavier lead nucleus at 60 per cent the speed of light, much faster than in lighter tin. At those high speeds, relativity makes the lead electrons behave as if they were much heavier too. And it is this high “effective mass” that ups the energy released when the electrons are transferred. Without relativistic effects, lead-acid batteries would generate just 0.39 volts, the team reports (Physical Review Letters, vol 106, p 018391). Roman empire succumbed to wild shifts in climate WE LIKE to blame the weather for all manner of ills, but the fall of the western Roman empire? A tree-ring history of European climate has uncovered several links between climate and the rise and fall of civilisations, including Rome. Climate was likely a factor alongside political failures and barbarian invasions, says Ulf Büntgen of the Swiss Federal Institute for Forest, Snow and Landscape Research in Birmensdorf. Büntgen reconstructed temperatures and rainfall in western Europe over the last 2500 years from nearly 9000 samples of oak, pine and larch. This showed that ALESSANDRO DI MEO/EPA/CORBIS IN BRIEF Smoking puts DNA at risk in 15 minutes concentrations of phenanthrene metabolites and determine the speed at which they formed in the body. The concentration of metabolites reached a peak around 15 to 30 minutes after smoke inhalation before tailing off, suggesting that cigarette smoke could potentially begin to affect genes within minutes of smoking beginning (Chemical Research in Toxicology, DOI: 10.1021/tx100345x). from AD 250 to 550 the climate flipped each decade from dry and cool to warm and wet. Such quick flips are disruptive, says Büntgen, because they harm farming but don’t allow people to adapt. Indeed, the period coincided with political upheaval and waves of human migration. By AD 500, the western Roman empire had fallen. The relatively stable medieval society that followed it benefited from less variable climatic conditions. Other studies have shown how war and climate can be intimately tied. For example, periods of unusually cold weather in China during the last millennium are thought to be linked to major bouts of warfare. But it is difficult to draw conclusions for the present day. Technology and trade can mitigate the effects of climate, says Halvard Buhaug of the Peace Research Institute Oslo in Norway. THE discovery that dust grains in deep space are spinning at mind- boggling rates could improve maps of the big bang’s afterglow. The Planck spacecraft and a ground-based instrument in the Canary Islands have observed microwaves emitted by an interstellar dust cloud that are consistent with the grains turning on their axis tens of billions of times a second. The grains are light enough to be set spinning by collisions with photons and fast- moving atoms, and because some are charged this would cause them to emit microwave radiation. Taking this into account will help correct distortions in maps of the cosmic microwave background, the afterglow of the big bang (arxiv.org/abs/1101.2031). They may be small, but they can twirl

Spinning cosmic dust motes set speed record

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16 | NewScientist | 22 January 2011

HERE’S another reason to kick the habit: within minutes of inhaling, regular smokers produce chemicals that cause genetic damage linked with cancer.

Polycyclic aromatic hydrocarbons (PAHs) present in tobacco smoke are one of the main culprits behind lung cancer. In the body they form metabolites that react readily with DNA to produce mutations

that in turn can cause tumours.Stephen Hecht and colleagues

at the University of Minnesota in Minneapolis asked 12 volunteers with a history of smoking to smoke a cigarette laced with phenanthrene, a type of PAH that binds with DNA but is non-carcinogenic.

By collecting blood samples before, during and after smoking, the team were able to track the

Car batteries run on relativity

YOU’VE got relativity to thank every time your car starts.

The transfer of electrons during a chemical reaction in lead-acid car batteries produces a potential of more than 2 volts. Yet for tin, which sits just above lead in the periodic table, a similar reaction is too feeble to power a battery. Now Pekka Pyykkö at the University of Helsinki in Finland and colleagues calculate that the difference is mainly due to relativity.

Electrons whiz around the heavier lead nucleus at 60 per cent the speed of light, much faster than in lighter tin. At those high speeds, relativity makes the lead electrons behave as if they were much heavier too. And it is this high “effective mass” that ups the energy released when the electrons are transferred. Without relativistic effects, lead-acid batteries would generate just 0.39 volts, the team reports (Physical Review Letters, vol 106, p 018391).

Roman empire succumbed to wild shifts in climate

WE LIKE to blame the weather for all manner of ills, but the fall of the western Roman empire?

A tree-ring history of European climate has uncovered several links between climate and the rise and fall of civilisations, including Rome. Climate was likely a factor alongside political failures and barbarian invasions, says Ulf Büntgen of the Swiss Federal Institute for Forest, Snow and Landscape Research in Birmensdorf.

Büntgen reconstructed temperatures and rainfall in western Europe over the last 2500 years from nearly 9000 samples of oak, pine and larch. This showed that

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Smoking puts DNA at risk in 15 minutes concentrations of phenanthrene metabolites and determine the speed at which they formed in the body.

The concentration of metabolites reached a peak around 15 to 30 minutes after smoke inhalation before tailing off, suggesting that cigarette smoke could potentially begin to affect genes within minutes of smoking beginning (Chemical Research in Toxicology, DOI: 10.1021/tx100345x).

from AD 250 to 550 the climate flipped each decade from dry and cool to warm and wet. Such quick flips are disruptive, says Büntgen, because they harm farming but don’t allow people to adapt. Indeed, the period coincided with political upheaval and waves of human migration. By AD 500, the western Roman empire had fallen. The relatively stable medieval society that followed it benefited from less variable climatic conditions.

Other studies have shown how war and climate can be intimately tied. For example, periods of unusually cold weather in China during the last millennium are thought to be linked to major bouts of warfare. But it is difficult to draw conclusions for the present day. Technology and trade can mitigate the effects of climate, says Halvard Buhaug of the Peace Research Institute Oslo in Norway.

THE discovery that dust grains in deep space are spinning at mind-boggling rates could improve maps of the big bang’s afterglow.

The Planck spacecraft and a ground-based instrument in the Canary Islands have observed microwaves emitted by an interstellar dust cloud that are consistent with the grains turning on their axis tens of billions of times a second. The grains are light enough to be set spinning by collisions with photons and fast-moving atoms, and because some are charged this would cause them to emit microwave radiation.

Taking this into account will help correct distortions in maps of the cosmic microwave background, the afterglow of the big bang (arxiv.org/abs/1101.2031).

They may be small, but they can twirl

110122_N_In Brief.indd 16 18/1/11 11:11:53