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Sun, 24 Sep 2017
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Fish

'City'-like area constructed by octopuses discovered in Australian bay

© Peter Godfrey-Smith
Octopus in 'Octlantis'
The discovery of an underwater city built by octopuses, dubbed Octlantis, has led researchers to conclude the mysterious mollusks aren't the loners we thought they were.

Octopuses have long been thought solitary creatures, with mating typically the only meeting between the two sexes. The creatures always go their separate ways afterward.

However in Jervis Bay, off the coast of New South Wales, Australia, researchers recently discovered a 'city' built by octopuses on rocky outcrops using piles of old shells.

Comment: Cephalopods are very intelligent creatures


Info

French scientists create bizarre magnetic material

© Gregory F. Maxwell
A blob of magnetic fluid that helps to visualize the magnetic field lines generated by the magnet underneath.
Scientists have discovered a new way to manipulate the magnetic structure of certain materials to form a kind of magnet known as fragmented spin ice. The resulting material possesses some of the weirdest magnetic properties known to science. Researchers are still trying to figure out exactly how these weird magnets behave, and learning to harness them could one day lead to novel applications. The discovery was published last month in the journal Nature Communications.

Tiny, frustrated magnets

Inside every material there are magnetic and nonmagnetic atoms. While both are essential for determining the material's many properties, the magnetic atoms control the magnetic properties. Acting like individual tiny magnets, the magnetic atoms collectively determine the overall magnetic properties of the material, which depends on the strength and coordinated orientation of each of these tiny atom-sized magnets. This is how we get a fridge magnet that behaves differently from the surface of the fridge. And it's why both differ when compared to the plastic fridge handle. The strength and orientation of the tiny magnets within each of those three items are closely related to a fundamental property of individual nuclei and electrons known as spin. Because of this close relationship, sometimes scientists simply call the tiny magnets "spins."

In spin ice the tiny magnets, or spins, are arranged in a very specific way. Unlike most magnetic materials, which take up relatively straightforward formations, such as lining up along a single direction, or just pointing in random directions, the individual spins inside a spin ice material have no simple way to organize themselves. This is usually due to the geometric arrangement of the atoms themselves -- when the atoms are put together in a certain way, the individual spins simply can't find a position that's consistently comfortable, as if they're trying to fit together like a bunch of badly built floor tiles.

Seismograph

The reasons why Mexico is terribly prone to the occurrence of earthquakes

© USGS
A map of the tectonic plate forces that subject Mexico to regular earthquakes.
If giants were playing a game of Jenga with countries as their table-tops, Mexico would be one of the last locations to get picked.

The country sits atop three of the Earth's largest tectonic plates - the North American plate, the Cocos Plate, and the Pacific Plate. Whenever these chunks of crust grind or butt up against one another, earthquakes happen. As a former lakebed, Mexico City is also home to soft soil that essentially acts as an amplifier for tremors, often making smaller earthquakes feel much larger.

On Tuesday, a deadly quake reverberated along the boundary between the Cocos and the North American plate as the southern-most plate slid beneath its northern neighbor. The 7.1-magnitude temblor, which struck about 3 miles northeast of the city of Raboso, happened less than two weeks after the country was struck by an even more powerful 8.1-magnitude quake and 32 years to the day after a deadly magnitude 8.1 quake killed more than 9,500 people in Mexico City.

Comment: For news and updates on the most recent quake to hit Mexico, see:

7.1 magnitude earthquake hits southern Mexico - Buildings collapse in Mexico City - Quake strikes on anniversary of 1985 'big one' (VIDEOS, IMAGES) - UPDATES


Cassiopaea

Astronomers baffled to discover stars that appear older than the universe

© NASA, ESA and T.M. Brown (STScI)
In the Andromeda galaxy, the oldest individual stars are found in the galaxy's halo. However, globular clusters and random field stars may prove to contain the oldest stars of all in the entire Universe.
If you understand how stars work, you can observe the physical properties of one of them and extrapolate its age, and know when it had to have been born. Stars undergo a lot of changes as they age: their radius, luminosity, and temperature all evolve as they burn through their fuel. But a star's lifespan, in general, is dependent on only two properties that it's born with: its mass and its metallicity, which is the amount of elements heavier than hydrogen and helium present within. The oldest stars we've found in the Universe are nearly pristine, where almost 100% of what makes them up is the hydrogen and helium left over from the Big Bang. They come in at over 13 billion years old, with the oldest at 14.5 billion. And this is a big problem, because the Universe itself is only 13.8 billion years old.

Info

AI can detect Alzheimer's years before symptoms show

© Dan Kitwood/Getty Images
The AI system uses brain scans to detect Alzheimer’s
The programme could help patients receive medication early to manage the disease.

Researchers have created an artificial intelligence (AI) programme that can detect signs of Alzheimer's disease up to ten years before symptoms appear.

Developed by a team at the University of Bari, in Italy, the computer system scans the brain for "tiny structural changes" that indicate the early stages of the disease, reports Engadget.

The AI was fed 38 MRI scans from Alzheimer's patients, and 29 from healthy patients, the website says, to help it learn common patterns in neurological activity and the symptoms of the disease.

Comment: See also: Researchers identify Alzheimer's tipping point: Excess glycation (i.e. too much sugar)




Info

Doubt cast on what causes the northern lights

© David Phan, CC by 2.0
UAlberta physicists have shown that the mechanism thought to be the cause of the northern lights fly in the face of what is has been commonly accepted in the world of space science.
What scientists thought caused certain classes of northern lights is not what causes certain classes of northern lights.

In a landmark study that has toppled what scientists know about the night sky, UAlberta physicists Robert Rankin and Dmytro Sydorenko found that the ionospheric feedback instability (IFI)-the mechanism thought to be the cause of certain types of northern lights-not only doesn't cause northern lights, it may not even exist at all.

"These findings fly in the face of what is now commonly accepted in the world of space science," said Rankin. "Our research shows that conditions necessary for the ionospheric feedback instability to occur are very unlikely, meaning it cannot be the cause of something as regular as the Aurora Borealis."

Saturn

After 20 years, Cassini burns up in the skies over Saturn

© JPL Cal-Tech/NASA
Cassini burned up like a comet above Saturn’s cloud tops just before 5 a.m. PDT on September 15. This artist’s illustration shows what it may have looked like.
After 20 years, nearly 300 orbits and pioneering discoveries, the spacecraft plunges to its death in Saturn's atmosphere

Cassini went down fighting.

After 20 years in space and 13 years orbiting Saturn, the veteran spacecraft spent its last 90 seconds or so firing its thrusters as hard as it could to keep sending Saturnian secrets back to Earth for as long as possible.

The spacecraft entered Saturn's atmosphere at about 3:31 a.m. PDT on September 15 and immediately began running through all of its stabilizing procedures to try to keep itself upright. The signal that Cassini had reached its destination arrived at Earth at 4:54 a.m., and cut out about a minute later as the spacecraft lost its battle with Saturn's atmosphere.

Comment: Rest in peace, Cassini.


Sun

Solar paradox: New theory may explain why sun's biggest flares occur as a solar cycle ebbs

© SDO/GSFC/NASA
SPOT OF BOTHER The same complicated sunspot spat out seven flares from September 4 to 10. This image shows in ultraviolet light the second-largest flare (bright flash at right), which was emitted on September 10.
A series of rapid-fire solar flares is providing the first chance to test a new theory of why the sun releases its biggest outbursts when its activity is ramping down. Migrating bands of magnetism that meet at the sun's equator may cause the biggest flares, even as the sun is going to sleep.

A single complex sunspot called Active Region 2673 emitted seven bright flares - powerful bursts of radiation triggered by magnetic activity - from September 4 to September 10. Four were X-class solar flares, the most intense kind. The strongest, released at 8:02 a.m. EDT on September 6, was an X9.3. The most powerful flare since 2006 (and the eighth largest since monitoring started in June 1996), it disrupted shortwave radio communication over Africa for up to an hour. It also flung a blob of energetic plasma, called a coronal mass ejection, speeding toward Earth, which sparked auroras the night of September 7 that were visible as far south as Arkansas.

All that activity is counterintuitive, as the sun is near the end of an unusually weak solar cycle, which began in 2008 (SN: 11/2/13, p. 22). The sun's magnetic activity waxes and wanes roughly every 11 years, generating more dark sunspots at the peak of the cycle and fewer at the trough.

Microscope 1

Researchers say miniscule DNA robots could soon end need for major surgeries

© Demin Liu / California Institute of Technology
A conceptual illustration of two DNA robots sorting fluorescent molecules
Robots made out of single strands of DNA could soon be used to precisely target and treat some of the world's deadliest diseases.

Developed by researchers from the California Institute of Technology, the microscopic machines have feet, arms and hands included in their design so they can maneuver and pick up molecules. They then recognize specific drop-off points and respond to signals telling them when to drop their cargo.

Telescope

Darker than asphalt: Hubble telescope captures images of pitch-black exoplanet

© NASA, ESA, and G. Bacon (STScI)
This artist’s impression shows the exoplanet WASP-12b — an alien world as black as fresh asphalt, orbiting a star like our Sun. Scientists were able to measure its albedo: the amount of light the planet reflects. The results showed that the planet is extremely dark at optical wavelengths.
Astronomers have discovered that the well-studied exoplanet WASP-12b reflects almost no light, making it appear essentially pitch black. This discovery sheds new light on the atmospheric composition of the planet and also refutes previous hypotheses about WASP-12b's atmosphere. The results are also in stark contrast to observations of another similarly sized exoplanet.

Using the Space Telescope Imaging Spectrograph (STIS) on the NASA/ESA Hubble Space Telescope, an international team led by astronomers at McGill University, Canada, and the University of Exeter, UK, have measured how much light the exoplanet WASP-12b reflects-its albedo-in order to learn more about the composition of its atmosphere.

The results were surprising, explains lead author Taylor Bell, a Master's student in astronomy at McGill University who is affiliated with the Institute for Research on Exoplanets: "The measured albedo of WASP-12b is 0.064 at most. This is an extremely low value, making the planet darker than fresh asphalt!" This makes WASP-12b two times less reflective than our Moon which has an albedo of 0.12. Bell adds: "The low albedo shows we still have a lot to learn about WASP-12b and other similar exoplanets."