You can't visit this tropical jungle. It's a forest of neurons snaking through a pig's brain. The brain cells, enlarged and coloured here, are being investigated to give scientists a clearer view of the mechanics of brain matter when it is hit hard.
Michel Destrade, an applied mathematician at the National University of Ireland, Galway, and colleagues obtained samples of pig brains from a local slaughterhouse to study the mechanics of brain matter undergoing rapid impacts. With the aim of improving the treatment of traumatic head injuries, they used the samples to create computer models of electrical signals inside the brain.
But during the course of the experiment, Destrade's student Badar Rashid decided to find out what white and grey matter inside a brain look like. He started with an image of neuron bundles taken using scanning electron microscopy, and blew it up to 4,000 times its actual size. He then added colour to the black and white result according to his own aesthetic.
Astrophile: Loner galaxy is seed of giant black hole
NGC 4178 enjoyed the single life. Even though the flat, disc-shaped galaxy was getting on a bit, it had a svelte spiral figure to be proud of. Its central black hole was perfect: not too small, not too large. It had never been involved in a major merger with another galaxy, and wanted to keep it that way. None of the unsightly bulges and warps associated with too much socialising for NGC 4178.
But other, more gregarious, galaxies were getting together all around it. They merged into grand spiral galaxies in a firework display of star formation which left them with impressive bulging bellies. They pooled their central black holes until they were billions of times larger than the sun. NGC 4178 watched it all from the sidelines, glad to maintain its trim appearance, although it couldn't help wondering if it wasn't missing out on something.
Unsociable galaxies are unusual. Astronomers think that galaxies grow from scraggly clusters of stars to elegant spirals like the Milky Way by merging and pooling their resources. Loners like NGC 4178, which has spent most of the lifetime of the universe avoiding the company of other galaxies, are useful tools for disentangling how this happens. They are rare snapshots of a simpler time.
"They are more representative of the initial stuff, from when structure started to form in the universe," says Nathan Secrest, a graduate student at George Mason University in Fairfax, Virginia. Galaxies like NGC 4178 are about "as pristine as you can get".
One of the puzzles they can help solve is the origin of supermassive black holes. Most large galaxies seem to have a giant black hole, millions or billions of times larger than the sun, at their centres. How these black holes got so big is still a mystery: did they grow gradually from mergers of smaller black holes, coalescing when their host galaxies merged? Or did they form when gas clouds collapsed in the early universe?
If these giants did grow by devouring their more diminutive counterparts, then the universe should also be riddled with middleweight black holes, tens of times the size of the sun. But only a few of these have ever been spotted.
But other, more gregarious, galaxies were getting together all around it. They merged into grand spiral galaxies in a firework display of star formation which left them with impressive bulging bellies. They pooled their central black holes until they were billions of times larger than the sun. NGC 4178 watched it all from the sidelines, glad to maintain its trim appearance, although it couldn't help wondering if it wasn't missing out on something.
Unsociable galaxies are unusual. Astronomers think that galaxies grow from scraggly clusters of stars to elegant spirals like the Milky Way by merging and pooling their resources. Loners like NGC 4178, which has spent most of the lifetime of the universe avoiding the company of other galaxies, are useful tools for disentangling how this happens. They are rare snapshots of a simpler time.
"They are more representative of the initial stuff, from when structure started to form in the universe," says Nathan Secrest, a graduate student at George Mason University in Fairfax, Virginia. Galaxies like NGC 4178 are about "as pristine as you can get".
One of the puzzles they can help solve is the origin of supermassive black holes. Most large galaxies seem to have a giant black hole, millions or billions of times larger than the sun, at their centres. How these black holes got so big is still a mystery: did they grow gradually from mergers of smaller black holes, coalescing when their host galaxies merged? Or did they form when gas clouds collapsed in the early universe?
If these giants did grow by devouring their more diminutive counterparts, then the universe should also be riddled with middleweight black holes, tens of times the size of the sun. But only a few of these have ever been spotted.
Earth's water piggybacked on asteroids, not comets
Whether comets or asteroids were the source of Earth's water has long been the subject of debate. Now an analysis of the composition of meteorites suggests the water did not originate in the outer solar system, a finding that favours asteroids as the vehicle for its arrival.
Both asteroids and comets are found in a region of the solar system known as the asteroid belt, which occupies a wide swathe of space between the orbits of Mars and Jupiter. However, comets with their icy tails would have been born in the chillier region of space between Saturn and Jupiter and then migrated into the asteroid belt.
To find out whether comets or asteroids were the parents of carbonaceous chondrites: rare meteorites which delivered water and volatile elements such as nitrogen, carbon and hydrogen to Earth, a team led by Conel Alexander from the Carnegie Institution of Washington in Washington DC measured the amount of deuterium &nash; a heavy isotope of hydrogen – in 86 chondrite samples found on Earth.
The further from the sun an object was formed, the more deuterium-rich it tends to be. The chondrites Alexander tested turned out to contain significantly less deuterium than comets, indicating that the chondrites most likely originated in a different place. "So, they probably formed closer in to the sun," says Alexander, most likely in the asteroid belt itself.
Despite the finding, exactly where the chondrites formed remains an open question – one that is particularly difficult to answer, says Fred Ciesla, a researcher at the University of Chicago, Illinois, who models the formation of planets. "You can't just say, you formed something at this one location and it sat there for 4.5 billion years. Things move around all the time," he says
Both asteroids and comets are found in a region of the solar system known as the asteroid belt, which occupies a wide swathe of space between the orbits of Mars and Jupiter. However, comets with their icy tails would have been born in the chillier region of space between Saturn and Jupiter and then migrated into the asteroid belt.
To find out whether comets or asteroids were the parents of carbonaceous chondrites: rare meteorites which delivered water and volatile elements such as nitrogen, carbon and hydrogen to Earth, a team led by Conel Alexander from the Carnegie Institution of Washington in Washington DC measured the amount of deuterium &nash; a heavy isotope of hydrogen – in 86 chondrite samples found on Earth.
The further from the sun an object was formed, the more deuterium-rich it tends to be. The chondrites Alexander tested turned out to contain significantly less deuterium than comets, indicating that the chondrites most likely originated in a different place. "So, they probably formed closer in to the sun," says Alexander, most likely in the asteroid belt itself.
Despite the finding, exactly where the chondrites formed remains an open question – one that is particularly difficult to answer, says Fred Ciesla, a researcher at the University of Chicago, Illinois, who models the formation of planets. "You can't just say, you formed something at this one location and it sat there for 4.5 billion years. Things move around all the time," he says
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