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Details from the inner life of a tooth


Science Daily
Thu, 19 Nov 2015 19:36 UTC
New X-ray method uses scattering to visualize nanostructures

Image
© Schaff et al. / Nature
Representation of the orientation of collagen fibers within a tooth sample. The sample’s three-dimensional nanostructure was computed from a large number of separate images recorded by X-ray scattering CT.
Both in materials science and in biomedical research it is important to be able to view minute nanostructures, for example in carbon-fiber materials and bones. A team from the Technical University of Munich (TUM), the University of Lund, Charite hospital in Berlin and the Paul Scherrer Institute (PSI) have now developed a new computed tomography method based on the scattering, rather than on the absorption, of X-rays. The technique makes it possible for the first time to visualize nanostructures in objects measuring just a few millimeters, allowing the researchers to view the precise three-dimensional structure of collagen fibers in a piece of human tooth.

In principle, X-ray computed tomography (CT) has been around since the 1960s: X-ray images are taken of an object from various directions, and a computer then uses the individual images to generate a three-dimensional image of the object. Contrast is produced by the differential absorption of X-rays in dissimilar materials. However, the new method, which was developed by Franz Pfeiffer, professor for Biomedical Physics at TUM and his team utilizes the scattering of X-rays rather than their absorption. The results have now been published in the journal Nature.
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Better Earth

New theory suggests Earth's mass extinction events caused by lack of trace minerals in world's oceans

Michael Slezak
New Scientist
Wed, 04 Nov 2015 17:02 UTC
Image
© Sheila Terry/SPL
Are you getting enough minerals? A new theory suggests most of Earth's mass extinction events could have been caused by a lack of essential trace elements in the world's oceans, causing fatal deficiencies in marine animals, from plankton to reptiles.

Earth has been hit with five mass extinction events. The two most dramatic ones had pretty clear causes. The dinosaurs were probably wiped out 66 million years ago thanks to a massive meteor falling on modern-day Mexico, while the end-Permian extinction, which wiped out 90 per cent of species 252 million years ago, was probably the result of massive volcanoes in Siberia.

But that leaves three other mass extinctions, with no agreed cause.

"It's a complex scenario," says John Long from Flinders University in Adelaide, Australia. He says there are probably a lot of causes conspiring to drive these mass extinctions. But his latest work suggests fluctuations in essential minerals in the ocean could be an important, and so-far completely unexplored, cause.
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Satellite

This massive exoplanet is being born right now

Irene Klotz
Discovery News
Wed, 18 Nov 2015 18:00 UTC
Image
© Karen L. Teramura, UH IfA
Artist's impression of a massive planet being born around a star 430 light-years from Earth.
For the first time, astronomers have directly observed a planet in the making.

The baby planet circles a very young, sun-like star located in a giant cloud of molecular gas 430 light-years from Earth in the constellation Taurus.

Astronomers had previously noted a hefty gap in the disk of gas and dust surrounding the star, known as LkCa 15. They suspected the gravitational pull of an evolving planet had cleared out an orbital zone, similar to how some moons circling Saturn create gaps in its rings.

Now, a new series of observations adds key details of the planet-in-the-making, showing for the first time how it is feeding on hydrogen gas.

"This discovery has far-reaching implications for our understanding of the planet-forming process and of the properties of young planets," Princeton University astrophysicist Zhaohuan Zhu wrote in a commentary in this week's Nature.
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Mars

Curiosity to check out dark and "active" Mars dunes

Mike Wall
Discovery News
Thu, 19 Nov 2015 04:00 UTC
Image
© NASA/JPL-Caltech/MSSS
This image, captured by NASA's Mars rover Curiosity on Sept. 25, 2015, shows a dark sand dune in the middle distance.
Curiosity is headed toward the dark Bagnold Dunes, which lie in the northwestern foothills of the towering Mount Sharp, and should begin investigating the sandy feature in the next few days, NASA officials said.

The Bagnold Dunes are substantial; Curiosity will study one dune that's as wide as a football field and as tall as a two-story building, NASA officials said. And they're active; observations by Mars orbiters show that some of the dunes are moving by as much as 3 feet (1 meter) per year.

"We've planned investigations that will not only tell us about modern dune activity on Mars but will also help us interpret the composition of sandstone layers made from dunes that turned into rock long ago," Bethany Ehlmann of the California Institute of Technology and NASA's Jet Propulsion Laboratory, both of which are located in Pasadena, California, said in a statement.

While Mars rovers have visited sandy swales in the past, no active dunes (which feature slopes steep enough for sand to slide down) have ever been studied up close on a world beyond Earth, NASA officials said.
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Galaxy

Galactic monster mystery revealed in ancient universe

Ian O'Neill
Discovery News
Thu, 19 Nov 2015 12:00 UTC
Image
© ESO/UltraVISTA team
ESO's VISTA survey telescope has spied a horde of previously hidden massive galaxies that existed when the Universe was in its infancy. By discovering and studying more of these galaxies than ever before, astronomers have for the first time found out exactly when such monster galaxies first appeared. The newly discovered massive galaxies are marked on this image of the UltraVISTA field.
Astronomers have detected something baffling at the furthest frontiers of our observable universe: massive galaxies -- lots of massive galaxies -- that shouldn't even exist.

Depending on the wavelength you observe the universe in, different celestial objects and cosmic phenomena present themselves. This rule is especially true when looking deeper into the universe — the further you look, the farther back in time you can see. Because the universe is expanding, the most ancient light traveling over these vast distances becomes more difficult to observe.

This nature of space-time becomes abundantly clear when considering new discoveries in the infrared realm — light has become so red-shifted (basically stretched) that only infrared observatories can see the faint glow at the most distant corners of the cosmos.

In an effort to reveal galaxies that have remained hidden from view at these vast distances, the Visible and Infrared Survey Telescope for Astronomy (VISTA) at the ESO's Paranal Observatory in Chile has revealed some of the youngest galaxies discovered to date, galaxies that were born a mere billion years after the Big Bang. But there's something weird going on: There's lots of them. And they're monsters.
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Arrow Down

Genetically modified humans could exist within 2 years

Julie Fidler
Natural Society
Wed, 18 Nov 2015 07:15 UTC
DNA
© Natural Society
The biotech firm Editas Medicine says that humans who have had their DNA genetically modified could exist within the next 2 years. The company announced that it will soon start the first trials of what it calls a groundbreaking new technique.

U.S.-based Editas is striving to become the first lab in the world to edit the DNA of patients suffering from leber congenital amaurosis (LCA), a genetic condition that causes severe vision loss at birth. Some LCA patients also experience central nervous system conditions, such as epilepsy, developmental delays and motor skill impairment.

LCA is said to be caused by defects in a gene responsible for the creation of a protein that is vital to vision. Editas Medicine scientists believe they can fix the mutated DNA using gene-editing technology known as CRISPRs.

CRISPRs, which stands for "clustered regularly interspaced short palindromic repeats," allows scientists to edit genes "with precision, efficiency and flexibility," Gizmodo explained in a May 5, 2015 article. Researchers have reportedly been able to create monkeys with targeted mutations and prevent HIV infection in human cells using this piece of biotechnology.

In early May, Chinese scientists said they'd successfully applied CRISPRs to nonviable human embryos, suggesting that the technology could someday be used to treat any genetic disease. It might even be used to create "designer babies" in the future, though that day is a long ways off.

Editas Medicine hopes to start a CRISPR trial with blind patients in 2017. It would be the first time the technology was ever used on humans.
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Telescope

Cool, dim dwarf star is magnetic powerhouse


ScienceDaily
Thu, 19 Nov 2015 00:00 UTC
red dwarf star
© NRAO/AUI/NSF; Dana Berry / SkyWorks
Artist impression of red dwarf star TVLM 513-46546. ALMA observations suggest that it has an amazingly powerful magnetic field, potentially associated with a flurry of solar-flare-like eruptions.
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered that a dim, cool dwarf star is generating a surprisingly powerful magnetic field, one that rivals the most intense magnetic regions of our own Sun.

The star's extraordinary magnetic field is potentially associated with a constant flurry of solar-flare-like eruptions. As with our Sun, these flares would trace tightly wound magnetic field lines that act like cosmic particle accelerators: warping the path of electrons and causing them to emit telltale radio signals that can be detected with ALMA.

Such intense flare activity, the astronomers note, would barrage nearby planets with charged particles.
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Magnify

Sensory illusion causes cells to self-destruct


ScienceDaily
Thu, 19 Nov 2015 00:00 UTC
Image
© Dmitry Knorre / Fotolia
Illustration of yeast cells. Even brainless single-celled yeast have sensory biases that can be hacked by a carefully engineered illusion, a finding that could be used to develop new approaches to fighting diseases such as cancer, say experts.
Magic tricks work because they take advantage of the brain's sensory assumptions, tricking audiences into seeing phantoms or overlooking sleights of hand. Now a team of UC San Francisco researchers has discovered that even brainless single-celled yeast have sensory biases that can be hacked by a carefully engineered illusion, a finding that could be used to develop new approaches to fighting diseases such as cancer.

"The ability to perceive and respond to the environment is a basic attribute of all living organisms, from the greatest to the smallest," said Wendell Lim, PhD, the study's senior author. "And so is the susceptibility to misperception. It doesn't matter if the illusion is based on molecular sensors within a single cell or neurons in the brain."

In the new study, published online Nov. 19, 2015 in Science Express, Lim and his team discovered that yeast cells falsely perceive a specifically timed pattern of stress -- caused by alternating between low and mildly increased sodium levels -- as a massive, continuously increasing ramp of stress. In response, the microbes end up over-responding and killing themselves. The results, Lim says, suggest a whole new way of looking at the perceptual abilities of simple cells and could even be used to develop new approaches to fighting diseases using the power of illusion.
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Snowflake Cold

Short winter days trigger aggression hormones differently based on sex


Science Daily
Wed, 18 Nov 2015 20:46 UTC
Territorial hamsters reveal biological mechanism behind the difference in male versus female aggression

Image
© Frank Scherbarth
A female hamster displays aggressive behavior.
Indiana University researchers have discovered a hormonal mechanism in hamsters that connects short winter days with increased aggression in females, and that it differs from the mechanism that controls this same response in males.

The work, which advances basic knowledge on the connection between certain sex hormones and aggression, could go on to advance research on the treatment of inappropriate aggression in humans.
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Toys

Babies have logical reasoning before age one


Science Daily
Wed, 18 Nov 2015 20:37 UTC
Deductive problem solving was previously thought to be beyond the reach of infants

Image
© Emory Health Sciences
A screen shot of a video from one of the experiments shows a subject watching the puppets interact.
Human infants are capable of deductive problem solving as early as 10 months of age, a new study by psychologists at Emory University and Bucknell finds. The journal Developmental Science is publishing the research, showing that babies can make transitive inferences about a social hierarchy of dominance.

"We found that within the first year of life, children can engage in this type of logical reasoning, which was previously thought to be beyond their reach until the age of about four or five years," says Stella Lourenco, the Emory University psychologist who led the study.

Comment: Babies have an eye for statistics
Babies And Beethoven: Infants Can Tell Happy Songs From Sad

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