Feb 20, 2018

Brain aging may begin earlier than expected

Brain illustration
Physicists have devised a new method of investigating brain function, opening a new frontier in the diagnoses of neurodegenerative and aging related diseases.

This new non-invasive technique could potentially be used for any diagnosis based on cardiovascular and metabolic-related diseases of the brain. The researchers at Lancaster University (UK) and Medical University of Gdansk (Poland) deciphered oscillations in the cerebrospinal fluid which lies between the scalp and skull.

A device for non-invasive recordings of this translucent fluid has been developed by researchers at the Technical University of Gdansk (Poland), and recordings on healthy subjects were made at the Medical University of Gdansk (Poland) and the University of Regina (Canada).

Using methods developed by physicists at Lancaster it has been shown that the circulation throughout the brain of this fluid is highly fluctuating, and that these fluctuations are slow but interconnected by the rhythms of breathing and the heart rate.

Researchers found that some of these oscillations are linked with blood pressure, but are generally slower, occurring at lower frequencies, which have been shown in previous studies to be related to oscillations in vascular motion and blood oxygenation.

Preliminary results showed evidence of a decline in the coherence between these oscillations in participants over the age of 25, indicating that brain aging may begin earlier than expected.

Professor Aneta Stefanovska from Lancaster University, who has been studying the physics of biological oscillations for over 20 years, said: "Combining the technique to noninvasively record the fluctuation corresponding to cerebrospinal fluid and our sophisticated methods to analyse oscillations which are not clock-like but rather vary in time around their natural values, we have come to an interesting and non-invasive method that can be used to study aging and changes due to various neurodegenerative brain aging may begin earlier than expected."

From Science Daily

Researchers invent tiny, light-powered wires to modulate brain's electrical signals

The rod at top right is positioned to modify electrical signaling between the neurons. The entire image is smaller than the diameter of a single human hair.
The human brain largely remains a black box: How the network of fast-moving electrical signals turns into thought, movement and disease remains poorly understood. But it is electrical, so it can be hacked -- the question is finding a precise, easy way to manipulate electrical signaling between neurons.

A new University of Chicago study shows how tiny, light-powered wires could be fashioned out of silicon to provide these electrical signals. Published Feb. 19 in Nature Nanotechnology, the study offers a new avenue to shed light on -- and perhaps someday treat -- brain disorders.

Ten years ago, the science world was alive with speculation about a recently discovered technique called optogenetics, which would manipulate neural activity with light. The problem is that it has to be done with genetics: inserting a gene into a target cell that would make it respond to light. Other ways of modulating neurons have since been suggested, but a perfect alternative remains elusive.

A team led by Asst. Prof. Bozhi Tian built minuscule wires previously designed for solar cells. These nanowires are so small that hundreds of them could sit side by side on the edge of a sheet of paper -- putting them on the same scale as the parts of cells they're trying to communicate with.

These nanowires combine two types of silicon to create a small electrical current when struck by light. Gold, diffused by a special process onto the surface of the wire, acts as a catalyst to promote electrochemical reactions.

"When the wire is in place and illuminated, the voltage difference between the inside and outside of the cell is slightly reduced. This lowers the barrier for the neuron to fire an electrical signal to its neighboring cells," Tian said.

The team tested the approach with rat neurons grown in a lab, and saw they could indeed trigger neurons to fire these electrical signals.

"The nice thing about it is that both gold and silicon are biologically compatible materials," said graduate student Ramya Parameswaran, the first author on the study. "Also, after they're injected into the body, structures of this size would degrade naturally within a couple of months."

"It's a fundamental but very promising approach," Tian said. They plan next to test the system in animals, which could both help researchers further understand how these electrical signals work in the brain as well as suggest ways to address problems like Parkinson's disease or psychiatric disorders.

Read more at Science Daily

Quintillionths of a second in slow motion

This is a view into the measuring chamber combining two pump-probe spectroscopy techniques thus allowing to observe and control ultrafast processes with attosecond resolution.
Many chemical processes run so fast that they are only roughly understood. To clarify these processes, a team from the Technical University of Munich (TUM) has now developed a methodology with a resolution of quintillionths of a second. The new technology stands to help better understand processes like photosynthesis and develop faster computer chips.

An important intermediary step in many chemical processes is ionization. A typical example of this is photosynthesis. The reactions take only a few femtoseconds (quadrillionths of a second) or even merely a few hundred attoseconds (quintillionths of a second). Because they run so extremely fast, only the initial and final products are known, but not the reaction paths or the intermediate products.

To observe such ultrafast processes, science needs a measurement technology that is faster than the observed process itself. So-called "pump-probe spectroscopy" makes this possible.

Here, the sample is excited using an initial laser pulse, which sets the reaction into motion. A second, time-delayed pulse queries the momentary state of the process. Multiple repetitions of the reaction with different time delays result in individual stop-motion images, which can then be compiled into a "film clip."

Two eyes see more than one

Now, a team of scientists headed by Birgitta Bernhardt, a former staff member at the Chair of Laser and X-ray Physics at TU Munich and meanwhile junior professor at the Institute of Applied Physics at the University of Jena, have for the first time succeeded in combining two pump-probe spectroscopy techniques using the inert gas krypton. This allowed them to shed light on the ultrafast ionization processes in a precision that has simply not been possible hitherto.

"Prior to our experiment, one could observe either which part of the exciting light was absorbed by the sample over time or measure what kind of and how many ions were created in the process," explains Bernhardt. "We have now combined the two techniques, which allows us to observe the precise steps by which the ionization takes place, how long these intermediate products exist and what precisely the exciting laser pulse causes in the sample."

Ultrafast processes under control

The combination of the two measuring techniques allows the scientists not only to record the ultrafast ionization processes. Thanks to the variation in the intensity of the second, probing laser pulse, they can now, for the first time, also control and in this way also influence the ionization dynamics.

"This kind of control is a very powerful instrument," explains Bernhardt. "If we can precisely understand and even influence fast ionization processes, we are able to learn a lot about light-driven processes like photosynthesis -- especially about the initial moments in which this complex machinery is set into motion and which is hardly understood to date."

Ultrafast computers

The technology developed by Bernhardt and her colleagues is also interesting for the development of new, faster computer chips in which the ionization of silicon plays a significant role. If the ionization states of silicon can not only be sampled on such a short time scale, but can also be set -- as the first experiments with krypton suggest -- scientists might one day be able to use this to develop novel and even faster computer technologies.

The work is the result of a collaboration between the workgroups led by Prof. Reinhard Kienberger, who heads the Chair of Laser and X-ray Physics at TU Munich and Stephan Fritzsche, professor at the Institute of Theoretical Physics of the Friedrich Schiller University of Jena.

Read more at Science Daily

Astronomers reveal secrets of most distant supernova ever detected

Top: Area of sky before the supernova was detected. Bottom: The supernova is detected.
An international team of astronomers led by the University of Southampton has confirmed the discovery of the most distant supernova ever detected -- a huge cosmic explosion that took place 10.5 billion years ago, or three-quarters the age of the Universe itself.

The exploding star, named DES16C2nm, was detected by the Dark Energy Survey (DES), an international collaboration to map several hundred million galaxies in order to find out more about dark energy -- the mysterious force believed to be causing the accelerated expansion of the Universe.

As detailed in a new study published in The Astrophysical Journal, light from the event has taken 10.5 billion years to reach Earth, making it the oldest supernova ever discovered and studied. The Universe itself is thought to be 13.8 billion years old.

A supernova is the explosion of a massive star at the end of its life cycle. DES16C2nm is classified as a superluminous supernova (SLSN), the brightest and rarest class of supernovae, first discovered ten years ago, thought to be caused by material falling onto the densest object in the Universe -- a rapidly rotating neutron star newly formed in the explosion of a massive star.

Lead author of the study Dr Mathew Smith, of the University of Southampton, said: "It's thrilling to be part of the survey that has discovered the oldest known supernova. DES16C2nm is extremely distant, extremely bright, and extremely rare -- not the sort of thing you stumble across every day as an astronomer.

"As well as being a very exciting discovery in its own right, the extreme distance of DES16C2nm gives us a unique insight into the nature of SLSN.

"The ultraviolet light from SLSN informs us of the amount of metal produced in the explosion and the temperature of the explosion itself, both of which are key to understanding what causes and drives these cosmic explosions."

Study co-author Professor Mark Sullivan, also of the University of Southampton, said: "Finding more distant events, to determine the variety and sheer number of these events, is the next step.

"Now we know how to find these objects at even greater distances, we are actively looking for more of them as part of the Dark Energy Survey."

DES16C2nm was first detected in August 2016, and its distance and extreme brightness confirmed in October that year using three of the world's most powerful telescopes -- the Very Large Telescope and the Magellan, in Chile, and the Keck Observatory, in Hawaii.

Study co-author Bob Nichol, Professor of Astrophysics at the University of Portsmouth, commented: "Such supernovae were not thought of when we started DES over a decade ago. Such discoveries show the importance of empirical science; sometimes you just have to go out and look up to find something amazing."

More than 400 scientists from over 25 institutions worldwide are involved in the DES, a five-year project which began in 2013.

The collaboration built and is using an extremely sensitive 570-megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

Over five years (2013-2018), the DES collaboration is using 525 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth.

Read more at Science Daily

Earth’s Crust Absorbs Lots of Carbon Dioxide, But Not Enough to Save Humanity

The carbon cycle of Earth's oceans
The seafloor is absorbing carbon dioxide, the greenhouse gas most associated with climate change, according to researchers at the University of Sydney in Australia. But while the ocean bottom might someday help reverse global warming, the process would take millions of years.

The authors of the study published recently in the journal Science Advances said their work provides a sense of scale for the damage humankind is wreaking on the planet today.

“We are starting to alter the environment — the surface conditions of the planet — a lot. It’s a fair question to ask, ‘Where will this ultimately lead?’” study co-author Dietmar Müller, a geophysicist. “In the very long run, we’re heating up the planet. Perhaps all ice will be melted one day. What safeguards has the planet built in? Ultimately, it will start cooling again. That will maintain habitability of the Earth in the very long run and make sure not all life will become extinct.”

With funding from the Australian Research Council and the Alfred P. Sloan Foundation, Müller and his colleague, sedimentologist Adriana Dutkiewicz, studied decades’ worth of drilling samples from the ocean floor. Using computer models that took into account changing water temperatures, they determined how much carbon the seabed absorbed.

They found that the ocean floor could absorb as much as 22 million tons of carbon annually.

That might sound like an enormous number, but in relative terms, it’s not. The planet’s atmosphere contains almost 950 billion tons of carbon. Humans dump around 37 billion tons of carbon into the atmosphere annually, according to the Global Carbon Project.

“This research is not about looking at short time scales,” said Müller.

Carbon sinks through subduction, or the process of tectonic plates on the earth’s crust moving and buckling under one another into the Earth’s mantle, the zone of magma and rock that is between the planet’s outer layer and core. As the plates under the water move over the eons, they rupture the Earth’s crust under the sea, forming fissures that expose minerals like calcite that capture carbon and turn into concrete-like materials. The warmer the water, the more efficient this chemical reaction that occurs.

The carbon doesn’t necessarily stay in the ocean crust forever. Instead, it’s recycled. Volcanos that often form along the ridges of subduction zones — like the so-called Ring of Fire along the rim of the Pacific Ocean — later spew up some of that carbon.

The researchers found that the capacity of the ocean to handle carbon runs in cycles of 26 million years. The planet is currently in an expansionary cycle, said Müller. It’s not clear why the crust operates according to this schedule, but geological records of fossils, salt deposits and other phenomena also follow patterns along similar time periods, he said.

Read more at Seeker

Feb 19, 2018

New algorithm can pinpoint mutations favored by natural selection in large sections of the human genome

It is hypothesized that natural selection favors lighter skin in northern latitudes to compensate for vitamin D deficiency due to lower UV radiation. iSAFE identified identical mutations in multiple non-African populations in 5 regions associated with skin pigmentation, suggesting an early response to the onset of selection as humans migrated out of Africa. Blue is derived and red is ancestral.
A team of scientists has developed an algorithm that can accurately pinpoint, in large regions of the human genome, mutations favored by natural selection. The finding provides deeper insight into how evolution works, and ultimately could lead to better treatments for genetic disorders. For example, adaptation to chronic hypoxia at high altitude can suggest targets for cardiovascular and other ischemic diseases.

The sequenced genome of a single individual yields about half a terabyte of data of information -- that's about as much information as you'll find on 106 DVDs. A population sample of size 1000 individuals contains 1000 times as much information. So to examine such a massive amount of data, researchers turned to computational techniques.

"Computer science and data science are playing a significant role to better understand the code of life and uncover the hidden patterns in our genome," said Ali Akbari, the paper's first author and a Ph.D. student in electrical and computer engineering at the University of California San Diego. "We are analyzing massively large sets of human genomic data to ultimately improve our understanding of genetic basis of diseases."

Researchers detail the algorithm, dubbed iSAFE, in the Feb. 19 issue of Nature Methods.

Many existing genomic analysis approaches can detect which regions of the human genome are evolving under selection pressure. Often, these regions are large, covering millions of base-pairs and do not shed light on the specific mutations that are responding to the selection pressure. iSAFE doesn't need to know the function of the genomic region it is analyzing or any demographic information for the human population it belongs to. Instead, the researchers used population genetic signals imprinted in the genomes of the sampled individuals and machine learning techniques to reliably identify the mutation favored by selection.

In natural selection, neighboring mutations 'hitchhike' with the mutation that is under positive selection, leading to a loss of genetic diversity near the favored mutation. iSAFE exploits signals in the neighboring sequences, the so-called "shoulder regions" to pinpoint the favored mutation.

"Finding the favored mutation among tens of thousands of other, hitchhiking, mutations was like a needle in a haystack problem," said Akbari, who works in the research group of computer science professor Vineet Bafna at the Jacobs School of Engineering at UC San Diego.

To test the algorithm, researchers ran iSAFE on regions of the genome that are home to known favored mutations. The algorithm ranked the correct mutation as the top one out of more than 21,000 possibilities in 69 percent of cases, as opposed to state of the art methods, which only did this in 10 percent of cases.

The algorithm also identified a host of previously unknown mutations, including five that involve genes related to pigmentation. In these cases, iSAFE identified identical mutations in multiple non-African populations. This suggests an early response to the onset of selection as humans migrated out of Africa.

The research was supported in part by the National Science Foundation and the National Institutes of Health.

Identifying the favored mutation in a positive selective sweep

Corresponding authors: Ali Akbari, Department of Electrical and Computer Engineering and Vineet Bafna, Department of Computer Science and Engineering, UC San Diego.

Read more at Science Daily

The starry sky shows nocturnal animals the way

Dung beetle.
Nocturnal animals can use the stars and the Milky Way to find their way during the darkest hours. While animal navigation is studied all over the world, some of the leading researchers are based at Lund University in Sweden. In a recent article they sum up the research so far and give their thoughts on challenges to come.

There are advantages to being active in the night. Fewer parasites are active and the same goes for predators. What is more, there are not as many competitors for food as there are during the day. For animals that migrate or search for food over vast distances in particular, the cooler hours of the night are preferable to the heat of the sun.

A key requirement for nocturnal animals is that they can hold their course in the dark. Migrating birds that take off at sunset rely on their magnetic compass, but also the star compass when they use individual stars for orientation. Dung beetles do not use individual stars. Instead they travel through the night with the help of the light from the Milky Way, which contrasts to the surrounding dark sky.

Studies also support that seals, moths, frogs and other animals use the starry sky to navigate at night.

"Animals with camera eyes, the type of eyes that we humans possess, can discern individual stars. Insects with compound eyes most likely cannot, but we believe that they can interpret the starry sky and the Milky Way as patterns of light," says James Foster, a biologist in the Faculty of Science at Lund University.

He has written a review article in Proceedings of the Royal Society B together with colleagues Marie Dacke, Dan-Eric Nilsson and Jochen Smolka. Their research addresses some exciting challenges.

"We still know very little about how nocturnal animals experience and interpret the night sky. For example, no one has yet determined whether, and how, migrating birds change their point of reference in the night sky when they pass the equator," James Foster explains.

Read more at Science Daily

First video of 'Dumbo' octopod hatchling shows that they look like mini-adults

"Dumbo" octopod hatchling in the laboratory.
Researchers who've gotten the first look at a deep-sea "dumbo" octopod hatchling report in Current Biology on February 19 that the young octopods look and act much like adults from the moment they emerge from an egg capsule. Dumbo octopods are so named because their fins resemble Dumbo the elephant's ears.

"Once the fins were observed while it was still in the bucket, it was clear that it was a 'dumbo' octopod," says Elizabeth Shea at the Delaware Museum of Natural History.

The researchers identified the octopod as a member of the Grimpoteuthis family, although the species identity remains unclear. Shea explained that's because species descriptions are typically based on mature adult specimens, often including features that are likely to change as an individual grows and matures.

Study co-author Tim Shank at Woods Hole Oceanographic Institution in Woods Hole, MA, was the first to see the hatchling in 2005 while serving as co-chief scientist of a Deep Atlantic Stepping Stones cruise, which used remotely operated vehicles (ROVs) to explore the New England and Corner Rise Seamount chains in the Northwest Atlantic. In the collected sample, he saw what looked like tan-colored golf balls attached to coral branches and collected several of them.

"With each successive collection, it became apparent that this was some sort of an egg case," Shank says. "The first few were open and empty, the next two contained a white gelatinous mass within, and the final collection yielded the specimen described in the paper."

When Tim first took the coral out of the ROV collection box and placed it in a 5-gallon bucket in the cold room, he noted that the egg case was tan-brown with a stippled texture and that the egg case was not broken. By the time he got the bucket out of the cold room and inspected the egg case, it was open and part of the hatchling was partially exposed.

At first, the hatchling wasn't moving much, if at all. But, after emerging fully from the egg case and being brought into the lab, the hatchling swam for about 10 minutes, which the researchers captured on film.

The researchers later used magnetic resonance imaging (MRI) to explore the hatchling's anatomy. Based on those findings, they were able to assign the specimen to the genus Grimpoteuthis.

"The virtual exploration and 3D reconstruction of the internal anatomy of this deep-sea creature was particularly revealing," says study co-author Alexander Ziegler from Rheinische Friedrich-Wilhelms-Universität Bonn in Germany. "I was impressed by the complexity of the central nervous system and the relative size of fins and the internal shell. However, for me as a zoologist, the most interesting aspect of our discovery remains the close interaction between the dumbo egg and the deep-sea coral host."

The observed behavior and advanced state of organ development showed that the hatchlings are fully formed from the start, with all the features required for fin swimming, visually and chemically sensing their environments, and capturing prey. An internal yolk sac gives the hatchlings a little time to successfully capture a first meal. Overall, they report, the evidence shows that dumbo octopods hatch as competent juveniles.

"We knew that adults are predominantly benthopelagic, that females lay eggs on the ocean bottom, and that octopod eggs come in a variety of sizes, colors, and textures," Shea says. "Our work connects the dots between a particular egg, a particular coral, and a particular octopod."

Read more at Science Daily

Fifteen new genes identified that shape our face

Scientists have identified 15 new genes that control the shape the face.
Researchers from KU Leuven (Belgium) and the universities of Pittsburgh, Stanford, and Penn State (US) have identified fifteen genes that determine our facial features. The findings were published in Nature Genetics.

Our DNA determines what we look like, including our facial features. That appeals to the popular imagination, as the potential applications are obvious. Doctors could use DNA for skull and facial reconstructive surgery, forensic examiners could sketch a perpetrator's face on the basis of DNA retrieved from a crime scene, and historians would be able to reconstruct facial features using DNA from days long gone.

But first, researchers need to figure out which genes in our DNA are responsible for specific characteristics of our face. "We're basically looking for needles in a haystack," says Seth Weinberg (Pittsburgh). "In the past, scientists selected specific features, including the distance between the eyes or the width of the mouth. They would then look for a connection between this feature and many genes. This has already led to the identification of a number of genes but, of course, the results are limited because only a small set of features are selected and tested."

In a new study conducted by KU Leuven in collaboration with the universities of Pittsburgh, Stanford and Penn State, the researchers adopted a different approach. "Our search doesn't focus on specific traits," lead author Peter Claes (KU Leuven) explains. "My colleagues from Pittsburgh and Penn State each provided a database with 3D images of faces and the corresponding DNA of these people. Each face was automatically subdivided into smaller modules. Next, we examined whether any locations in the DNA matched these modules. This modular division technique made it possible for the first time to check for an unprecedented number of facial features."

The scientists were able to identify fifteen locations in our DNA. The Stanford team found out that genomic loci linked to these modular facial features are active when our face develops in the womb. "Furthermore, we also discovered that different genetic variants identified in the study are associated with regions of the genome that influence when, where and how much genes are expressed," says Joanna Wysocka (Stanford). Seven of the fifteen identified genes are linked to the nose, and that's good news, Peter Claes (KU Leuven) continues. "A skull doesn't contain any traces of the nose, which only consists of soft tissue and cartilage. Therefore, when forensic scientists want to reconstruct a face on the basis of a skull, the nose is the main obstacle. If the skull also yields DNA, it would become much easier in the future to determine the shape of the nose."

In any case, the four universities will continue their research using even bigger databases.

Read more at Science Daily

Feb 18, 2018

Hubble sees Neptune's mysterious shrinking storm

This series of Hubble Space Telescope images taken over 2 years tracks the demise of a giant dark vortex on the planet Neptune. The oval-shaped spot has shrunk from 3,100 miles across its long axis to 2,300 miles across, over the Hubble observation period.
Three billion miles away on the farthest known major planet in our solar system, an ominous, dark storm - once big enough to stretch across the Atlantic Ocean from Boston to Portugal - is shrinking out of existence as seen in pictures of Neptune taken by NASA's Hubble Space Telescope.

Immense dark storms on Neptune were first discovered in the late 1980s by NASA's Voyager 2 spacecraft. Since then, only Hubble has had the sharpness in blue light to track these elusive features that have played a game of peek-a-boo over the years. Hubble found two dark storms that appeared in the mid-1990s and then vanished. This latest storm was first seen in 2015, but is now shrinking.

Like Jupiter's Great Red Spot (GRS), the storm swirls in an anti-cyclonic direction and is dredging up material from deep inside the ice giant planet's atmosphere. The elusive feature gives astronomers a unique opportunity to study Neptune's deep winds, which can't be directly measured.

The dark spot material may be hydrogen sulfide, with the pungent smell of rotten eggs. Joshua Tollefson from the University of California at Berkeley explained, "The particles themselves are still highly reflective; they are just slightly darker than the particles in the surrounding atmosphere."

Unlike Jupiter's GRS, which has been visible for at least 200 years, Neptune's dark vortices only last a few years. This is the first one that actually has been photographed as it is dying.

"We have no evidence of how these vortices are formed or how fast they rotate," said Agustín Sánchez-Lavega from the University of the Basque Country in Spain. "It is most likely that they arise from an instability in the sheared eastward and westward winds."

The dark vortex is behaving differently from what planet-watchers predicted. "It looks like we're capturing the demise of this dark vortex, and it's different from what well-known studies led us to expect," said Michael H. Wong of the University of California at Berkeley, referring to work by Ray LeBeau (now at St. Louis University) and Tim Dowling's team at the University of Louisville. "Their dynamical simulations said that anticyclones under Neptune's wind shear would probably drift toward the equator. We thought that once the vortex got too close to the equator, it would break up and perhaps create a spectacular outburst of cloud activity."

But the dark spot, which was first seen at mid-southern latitudes, has apparently faded away rather than going out with a bang. That may be related to the surprising direction of its measured drift: toward the south pole, instead of northward toward the equator. Unlike Jupiter's GRS, the Neptune spot is not as tightly constrained by numerous alternating wind jets (seen as bands in Jupiter's atmosphere). Neptune seems to only have three broad jets: a westward one at the equator, and eastward ones around the north and south poles. The vortex should be free to change traffic lanes and cruise anywhere in between the jets.

"No facilities other than Hubble and Voyager have observed these vortices. For now, only Hubble can provide the data we need to understand how common or rare these fascinating neptunian weather systems may be," said Wong.

The first images of the dark vortex are from the Outer Planet Atmospheres Legacy (OPAL) program, a long-term Hubble project that annually captures global maps of our solar system's four outer planets. Only Hubble has the unique capability to probe these worlds in ultraviolet light, which yields important information not available to other present-day telescopes. Additional data, from a Hubble program targeting the dark vortex, are from an international team including Wong, Tollefson, Sánchez-Lavega, Andrew Hsu, Imke de Pater, Amy Simon, Ricardo Hueso, Lawrence Sromovsky, Patrick Fry, Statia Luszcz-Cook, Heidi Hammel, Marc Delcroix, Katherine de Kleer, Glenn Orton, and Christoph Baranec.

Read more at Science Daily