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Mongol hordes beaten by rainy weather
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in Brief Gas giants’ gravity could herd meteors
Fear and pleasure work their way separately into memory ONE region, two routes. Memories of pleasure and fear are laid down in the same part of the brain, but along different pathways. Karl Deisseroth of Stanford University and his team gave mice a pleasurable experience using cocaine, or frightened them with electric shocks. After death, the team washed away the fatty materials in the mouse brains, making them transparent. Dyes that highlighted previously active cells allowed them to see which networks of neurons were involved in each experience. Although both types of memory were laid down in
the medial prefrontal cortex, they were stored along separate paths or axonal projections, which in turn linked to different brain regions (Cell, DOI: 10.1016/ j.cell.2016.05.010). This could have implications for treating mental health disorders, says Deisseroth. Some drugs, as well as transcranial magnetic stimulation, target the prefrontal cortex. “Now we know the signals for fear and pleasure can be transmitted by different axonal projections, new targeted treatments might be envisioned,” he says. Joff Lee at the University of Birmingham, UK, agrees that the finding might lead to better treatments. If we do not target the right neurons, drugs intended to reduce fear may inadvertently also affect how we process pleasure, Lee says.
Mongol hordes beaten by rainy weather IT HAS always mystified historians. After a string of major victories, the Mongol army suddenly retreated from central Europe in 1242. Some argue that Mongolian politics forced the withdrawal, while others credit the strength of fortified towns. But Europe could have been rescued by its own bad weather, an analysis of tree rings and historical documents finds. The Mongol cavalry fed its 14 | NewScientist | 4 June 2016
horses on the grassy Eurasian steppe, says Nicola Di Cosmo of Princeton University. A warm climate in the early 1200s made the grasslands lush and this, in turn, helped the Mongols extend their empire into Russia, he says. But Hungary has a high water table compared with the rest of the steppe and floods easily. Analysing tree rings in the region, Di Cosmo and his colleagues
found that Hungary had a cold, wet winter in early 1242 that turned Hungary’s central plain into a huge swamp. Lacking pasture for their horses, the Mongols fell back to drier highlands and then to Russia (Scientific Reports, doi.org/bhxt). While climate wasn’t the only factor in the retreat, it would be a mistake to ignore it, says Di Cosmo. “It’s like saying the winter in Russia had no effect on Napoleon’s army.”
A RARE cosmic balancing act could create spectacular meteor showers. The effect requires clockwork precision – but it may be responsible for some of the best showers in recent memory. The Perseid meteors, which occur every August, come from fragments of ice and rock ejected by comet Swift-Tuttle. From 1989 to 1994, the meteors came in bright, oddly staccato bursts. Now a team led by Aswin Sekhar at the University of Oslo in Norway thinks they know why: a rare gravitational dance between the Perseids, Saturn and Jupiter. At key points in the Perseid stream, meteors may clump due to nudges from what’s called a threebody orbital resonance (arxiv.org/ abs/1605.06340). The showers of the early 1990s may have occurred when Earth passed through a clump of Perseids herded together by the resonance – but the next such event may not be until 2111.
Vaccinations rise, web searches fall NO NEED to Google it. Chickenpox vaccination programmes have meant that fewer people are looking up the disease online. Australia, Germany and the US have been immunising children against the varicella zoster virus for more than a decade, but the success of these initiatives is hard to pin down. Now Kevin Bakker of the University of Michigan and his colleagues have found that between 2004 and 2015, Google searches for chickenpox fell in various countries once they began immunising against it (PNAS, DOI: 10.1073/pnas.1523941113). Compared with clinical reporting, such “digital epidemiology” is much quicker and cheaper, Bakker says.
in Brief Gas giants’ gravity could herd meteors
Fear and pleasure work their way separately into memory ONE region, two routes. Memories of pleasure and fear are laid down in the same part of the brain, but along different pathways. Karl Deisseroth of Stanford University and his team gave mice a pleasurable experience using cocaine, or frightened them with electric shocks. After death, the team washed away the fatty materials in the mouse brains, making them transparent. Dyes that highlighted previously active cells allowed them to see which networks of neurons were involved in each experience. Although both types of memory were laid down in
the medial prefrontal cortex, they were stored along separate paths or axonal projections, which in turn linked to different brain regions (Cell, DOI: 10.1016/ j.cell.2016.05.010). This could have implications for treating mental health disorders, says Deisseroth. Some drugs, as well as transcranial magnetic stimulation, target the prefrontal cortex. “Now we know the signals for fear and pleasure can be transmitted by different axonal projections, new targeted treatments might be envisioned,” he says. Joff Lee at the University of Birmingham, UK, agrees that the finding might lead to better treatments. If we do not target the right neurons, drugs intended to reduce fear may inadvertently also affect how we process pleasure, Lee says.
Mongol hordes beaten by rainy weather IT HAS always mystified historians. After a string of major victories, the Mongol army suddenly retreated from central Europe in 1242. Some argue that Mongolian politics forced the withdrawal, while others credit the strength of fortified towns. But Europe could have been rescued by its own bad weather, an analysis of tree rings and historical documents finds. The Mongol cavalry fed its 14 | NewScientist | 4 June 2016
horses on the grassy Eurasian steppe, says Nicola Di Cosmo of Princeton University. A warm climate in the early 1200s made the grasslands lush and this, in turn, helped the Mongols extend their empire into Russia, he says. But Hungary has a high water table compared with the rest of the steppe and floods easily. Analysing tree rings in the region, Di Cosmo and his colleagues
found that Hungary had a cold, wet winter in early 1242 that turned Hungary’s central plain into a huge swamp. Lacking pasture for their horses, the Mongols fell back to drier highlands and then to Russia (Scientific Reports, doi.org/bhxt). While climate wasn’t the only factor in the retreat, it would be a mistake to ignore it, says Di Cosmo. “It’s like saying the winter in Russia had no effect on Napoleon’s army.”
A RARE cosmic balancing act could create spectacular meteor showers. The effect requires clockwork precision – but it may be responsible for some of the best showers in recent memory. The Perseid meteors, which occur every August, come from fragments of ice and rock ejected by comet Swift-Tuttle. From 1989 to 1994, the meteors came in bright, oddly staccato bursts. Now a team led by Aswin Sekhar at the University of Oslo in Norway thinks they know why: a rare gravitational dance between the Perseids, Saturn and Jupiter. At key points in the Perseid stream, meteors may clump due to nudges from what’s called a threebody orbital resonance (arxiv.org/ abs/1605.06340). The showers of the early 1990s may have occurred when Earth passed through a clump of Perseids herded together by the resonance – but the next such event may not be until 2111.
Vaccinations rise, web searches fall NO NEED to Google it. Chickenpox vaccination programmes have meant that fewer people are looking up the disease online. Australia, Germany and the US have been immunising children against the varicella zoster virus for more than a decade, but the success of these initiatives is hard to pin down. Now Kevin Bakker of the University of Michigan and his colleagues have found that between 2004 and 2015, Google searches for chickenpox fell in various countries once they began immunising against it (PNAS, DOI: 10.1073/pnas.1523941113). Compared with clinical reporting, such “digital epidemiology” is much quicker and cheaper, Bakker says.