The heavy-duty material used to build bridges and sculpt skyscrapers could learn a few tricks from humble bones.

Steel’s weakness is its tendency to develop microscopic cracks that eventually make the material fracture. Repeated cycles of stress — daily rush hour traffic passing over a bridge, for example — nurture these cracks, which often aren’t apparent until the steel collapses. Bones, however, have a complex inner structure that helps them deal with stress. This structure differs depending on the scale, with tiny vertically aligned fibers building up into larger cylinders.
To mimic this variability, researchers fabricated steel with thin, alternating nanoscale layers of different crystal structures, some of which were just unstable enough to morph a bit under stress. That complicated microstructure prevented cracks from spreading in a straight line, slowing their take-over and preventing the material from collapsing, the scientists report in the March 10 Science. This experimental steel requires much more testing before it can be used in construction, says study coauthor C. Cem Tasan, a materials scientist at MIT. But the principles could be applied to other mixed-composition metals, too.

Soon after systems biologist Juergen Hahn published a paper describing a way to predict whether a child has autism from a blood sample, the notes from parents began arriving. “I have a bunch of parents writing me now who want to test their kids,” says Hahn, of Rensselaer Polytechnic Institute in Troy, N.Y. “I can’t do that.”

That’s because despite their promise, his group’s results, reported March 16 in PLOS Computational Biology, are preliminary — nowhere close to a debut in a clinical setting. The test will need to be confirmed and repeated in different children before it can be used to help diagnose autism. Still, the work of Hahn and colleagues, along with other recent papers, illustrates how the hunt for a concrete biological signature of autism, a biomarker, is gaining speed.
Currently, pediatricians, child psychologists and therapists rely on behavioral observations and questionnaires, measures with limitations. Barring genetic tests for a handful of rare mutations, there are no blood draws, brain scans or other biological tests that can reveal whether a child has — or will get — autism.

Objective tests would be incredibly useful, helping provide an early diagnosis that could lead to therapy in the first year of life, when the brain is the most malleable. A reliable biomarker might also help distinguish various types of autism, divisions that could reveal who would benefit from certain therapies. And some biomarkers may reveal a deeper understanding of how the brain normally develops.

Scientists are simultaneously sanguine and realistic about the prospect of uncovering solid autism biomarkers. “We have great tools that we’ve never had before,” says psychiatrist Joseph Piven of the University of North Carolina School of Medicine in Chapel Hill. Scientists can assess genes quickly and cheaply, gather sophisticated information about the shape and behavior of the brain, and rely on large organized research collaborations aimed at understanding autism. “That said, I’ve done this long enough to know that people make all kinds of claims: ‘In the next five years or the next 10 years, we’re going to do this,’” Piven says. The reality, he says, is more challenging.
Hahn agrees. “I think it will take quite a bit longer” to find clinically useful biomarkers, he says. “It’s not what parents want to hear. The thing is, this is a very difficult medical disease with many different manifestations.”
Researchers have turned up differences in the brain between people with and without autism, including size and growth patterns, connections between areas and brain cell behavior. But the variability in autism symptoms — and causes — has prompted scientists to look beyond the brain in the search for biomarkers.

“Autism may not be purely a brain disorder,” says neuroscientist Eric Courchesne of the University of California, San Diego. Scientists are looking for important clues to autism in gut microbes, skin cells, the immune system and factors that circulate in the blood.

That was the rationale behind Hahn and colleagues’ experiment, which compared compounds in the blood of 83 children with autism to those of 76 children without the disorder. The researchers focused on a group of molecules implicated in autism. These molecules carry out an intricate series of metabolic reactions called folate-dependent one-carbon metabolism and transsulfuration. Earlier work suggested that these processes are altered in people with autism.

Hahn and colleagues developed a statistical tool that examined the relationships between 24 of these molecules. Instead of looking at the concentration of each individual player, the team wondered if a more global view would help. “Could you find patterns in these that give you a much more predictive pattern than if you look at them one by one?” he asks. The answer, their results showed, was yes.

The statistical tool correctly called 97.6 percent of the children with autism and 96.1 percent of the children without. Just two of 83 children on the autism spectrum were misclassified as being neurotypical, and three of 76 children without autism were misclassified as being autistic. Compared with other methods described in the scientific literature, “the numbers we got out were very, very good,” Hahn says.

Those results are “quite interesting as an example of a blood test,” says neuroscientist Dwight German of the University of Texas Southwestern Medical Center in Dallas. But as a researcher who also works on blood-based biomarkers of autism, German is familiar with a huge caveat: Blood can be fickle. Medications, age and even time of day can influence factors in the blood, he says. “There’s an awful lot of testing you have to do to show that what you’re measuring is related to the disorder and not what they ate for breakfast,” he says.

If these metabolic differences are present just after birth, the blood test could be an extremely early indicator of autism. But much more work needs to be done to validate the new approach, including tests on children younger than 3, Hahn says.

Other issues need to be resolved, too. When tested on 47 siblings of people with autism, children who presumably share genetics and environment with an autistic sibling but who don’t have the disorder themselves, the statistical tool’s performance worsened a bit. The tool incorrectly classified four of the 47 siblings as having autism.

For tougher distinctions between high-risk kids like these, scientists have had success looking back to the brain. Recently, Piven and colleagues studied babies born to parents who already had an autistic child. These “baby sibs” have about a one in five chance of developing autism themselves, a rate higher than that of a child without an autistic sibling. By studying this high-risk group, Piven and colleagues have found brain features that are associated with even more risk.
Researchers had suspected that at some point early in life, brains grow too much in children who will go on to develop autism. Piven and colleagues scanned the brains of 106 babies with older siblings with autism at 6, 12 and 24 months of age. The researchers also included 42 low-risk infants.

At 6 and 12 months of age, the 15 babies who went on to develop autism had more growth in the outer surface of their brains, the cortex, than both the high-risk babies who didn’t develop autism and the low-risk babies, the researchers reported February 16 in Nature. A computer program that analyzed brain growth predicted whether these high-risk infants would go on to develop autism. On a second set of babies, the classification performed well, successfully calling eight out of 10 babies who would go on to develop autism by 24 months of age.

Other work by Piven and colleagues has turned up other brain differences in high-risk babies. Babies who will go on to develop autism have more cerebrospinal fluid on a certain part of the outer layer of their brains than those who don’t develop the disorder. But the results, published online March 6 in Biological Psychiatry, fell short of the predictive power of the brain overgrowth results, Piven says.

Both of these brain scan studies apply only to high-risk babies. It’s not known whether similar tests would work on children without siblings with autism. But it’s possible that these types of detailed findings can help distinguish varieties of autism, and those are distinctions that must be made before scientists can make progress, Piven says. “We call [autism] one thing, but it’s many, many different things. And until we are able to grapple with that in a more meaningful way, it’s sort of an intractable problem.”

Child and adolescent psychiatrist Robert Hendren, of the University of California, San Francisco, envisions a time when this collection of individual disorders collectively called autism are all cataloged in detail, thanks to biomarkers. “We’ll call it autism 23 or autism 14, and we’ll say, ‘We know this is the process that’s going on, and this is how we’re going to personalize our treatments for this person.’”

On the way to that goal, a big breakthrough is unlikely, says Piven. It’s not like the discovery of penicillin for bacterial infections. “You give it, and 10 days later, everything is fine. This isn’t going to be like that.” Even so, the breadth and enthusiasm of the field is promising, he says. “This whole idea of looking at early biomarkers is a new way of thinking, and we have enormous capabilities to make this reality.”

Earthquake-powered shifts along the seafloor that push water forward, not just up, could help supersize tsunamis.

By combining laboratory experiments, computer simulations and real-world observations, researchers discovered that the horizontal movement of sloped seafloor during an underwater earthquake can give tsunamis a critical boost. Scientists previously assumed that vertical movement alone contributed most of a tsunami’s energy.

More than half of the energy for the unexpectedly large tsunami that devastated Japan in 2011 (SN Online: 6/16/11) originated from the horizontal movement of the seafloor, the researchers estimate. Accounting for this lateral motion could explain why some earthquakes generate large tsunamis while others don’t, the researchers report in a paper to be published in the Journal of Geophysical Research: Oceans.
“For the last 30 years, we’ve been moving in the wrong direction to do a good job predicting tsunamis,” says study coauthor Tony Song, an oceanographer at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “This new theory will lead to a better predictive approach than we have now.”

The largest tsunamis form following earthquakes that occur along tectonic boundaries where an oceanic plate sinks below a continental plate. That movement isn’t always smooth; sections of the two plates can stick together. As the bottom oceanic plate sinks, it bends the top continental plate downward like a weighed-down diving board. Eventually, the pent-up stress becomes too much and the plates abruptly unstick, causing the overlying plate to snap upward and triggering an earthquake. That upward movement lifts the seafloor, displacing huge volumes of water that pile up on the sea surface and spread outward as a tsunami.

These deep-sea earthquakes shift the seafloor sideways, too. The earthquake off the coast of Japan in 2011, for instance, not only lifted the ocean floor three to five meters; it also caused up to 58 meters of horizontal movement. Such lateral motion, however big, is mostly ignored in tsunami science, largely because of a 1982 laboratory study that found no connection between horizontal ground motion and wave height. The experiment used in that study, Song argues, wasn’t a properly sized-down model of the dimensions of the seafloor and overlying ocean. If lateral motion takes place on a sloped segment of the seafloor, he thought, then the shift can push large volumes of water sideways and add momentum to the budding tsunami.

Using two wave-making machines at Oregon State University in Corvallis, Song and colleagues revisited the decades-old experiment. Oarlike paddles pushed water upward and outward in some tests and just upward in others. Adding horizontal motion caused higher waves than vertical motion alone, the researchers found.

By combining the experimental results with a new tsunami computer simulation that incorporates lateral movement, the researchers could account for the unusual size of the 2004 Indian Ocean tsunami. That tsunami, one of the worst natural disasters on record, was bigger than uplift alone can explain.
Using GPS sensors to measure the horizontal movement of the seafloor during an earthquake will enable more accurate tsunami forecasts before the wave is spotted by ocean buoys, Song proposes.

The new work makes a convincing case that horizontal motion contributes to tsunami generation, says Eddie Bernard, a tsunami scientist emeritus at the National Oceanic and Atmospheric Administration’s Center for Tsunami Research in Seattle. But just how much that movement contributes to a tsunami’s overall height is unclear. It could be much less than Song and colleagues predict, he says.

Other seafloor events that can follow a large earthquake — such as huge numbers of water-displacing landslides — could also boost a tsunami’s size. Until all of the factors are known, Bernard says, tsunami forecasters will probably be best off doing what they do now: waiting for a tsunami to form after an earthquake before predicting the wave’s size and trajectory.

A potential sign of dark matter is looking less convincing in the wake of a new analysis.

High-energy blips of radiation known as gamma rays seem to be streaming from the center of the Milky Way in excess. Some scientists have proposed that dark matter could be the cause of that overabundance. Particles of dark matter — an invisible and unidentified substance that makes up the bulk of the matter in the cosmos — could be annihilating in the center of the galaxy, producing gamma rays (SN Online: 11/4/14).

In the new study, scientists scrutinized the latest data from the Fermi Gamma-ray Space Telescope. At the galaxy’s center, the researchers found more gamma rays than they could explain, they report in a paper posted online April 12 at arXiv.org. But, when the researchers compared the region at the center of the galaxy with control regions away from the galaxy’s center — where dark matter signals wouldn’t be expected — they also found spots with more gamma rays than expected.

“What I see in the control regions looks just like what I see in the galactic center,” says astrophysicist Andrea Albert of Los Alamos National Laboratory in New Mexico, one of the researchers who worked on the analysis. So they can’t claim that dark matter is the cause. “That’s a bummer,” she says.

Premature babies may one day continue developing in an artificial womb, new work with sheep suggests.

A fluid-filled bag that mimics the womb kept premature lambs alive and developing normally for four weeks, researchers report April 25 in Nature Communications. Lambs at a gestational age equivalent to that of a 23- or 24-week-old human fetus had normal lung and brain development after a month in the artificial womb, the researchers discovered. A similar device might be ready for use in premature human babies in three to five years if additional animal tests pan out, study coauthor Alan Flake estimates.
But this is not the science fiction scenario of Brave New World, in which humans were grown entirely in tanks, says Flake, a pediatric and fetal surgeon at the Children’s Hospital of Philadelphia. “I don’t view this as something that’s going to replace mothers.” Technical and biological hurdles would prevent doctors from using an artificial womb to rescue premature babies younger than about 23 weeks, he says.

Researchers have been trying for 60 years to make an artificial womb or artificial placenta, says George Mychaliska, a pediatric and fetal surgeon at the University of Michigan Medical School in Ann Arbor. His own group has been working on an artificial placenta, or what he calls an “extra-corporeal life-support” system for premature babies for a decade. “One month is very impressive, and the data behind that is strong,” Mychaliska says, but adds that what works for lambs might not work as well for human babies.

In the United States, thousands of babies each year are born extremely premature, before 28 weeks of pregnancy. Of those born at the edge of viability, at 23 weeks of gestation, up to about 70 percent die; many of the survivors have lung and other health problems partly caused by efforts to keep them alive. Putting premature babies on ventilators to get oxygen into their bodies has mixed results, Mychaliska says. “The same treatment that is potentially saving their lives is also damaging their lungs.”

Flake and colleagues’ initial efforts to make an artificial womb — including submerging lambs in fluid in a tank — failed. Infection soon set in, killing the animals. This time, the researchers tried to mimic more closely what happens during normal pregnancy. In the new system, a lamb is surgically delivered via cesarean section and placed in a sterile bag filled with an electrolyte fluid. Because the bag is closed, the risk of infection is reduced. Tubes carrying oxygenated blood plug into the lamb’s umbilical cord, and the beating of the fetus’s heart pumps the blood at volumes and pressure comparable to what is normally delivered by the placenta. Other groups have put tubes in the neck and used an external pump to circulate the blood, which may put too much pressure on fetal hearts, causing heart failure, Flake says.

Like a real womb, the artificial one also bathes lambs in the fluid needed for proper lung development. Flake’s team prevents the lambs from taking a breath because even a little air might harm lung development.
Premature babies would have to be delivered surgically and placed immediately into the fluid incubator. That would rule out about 50 percent of extremely premature babies because they are born vaginally, Flake says.

Flake’s version of the device may not be feasible for human babies for several technical reasons, too, Mychaliska says. One barrier is that the system requires a delicate fetal surgery to connect the umbilical cord to the incubator while the baby is still attached to the mother. Few hospitals are equipped to perform such an operation, he says.

Flake acknowledges that several kinks must still be worked out before the artificial womb can be tested on human babies. “We have a lot to learn in terms of its capabilities and its safety,” he says, but his group may soon be ready to begin human clinical trials. “We honestly think it could be as early as two to three years from now — and certainly within five years — that we’ll be applying it to humans.”

Mouse sperm could win awards for resilience. Sperm freeze-dried and sent into space for months of exposure to high levels of solar radiation later produced healthy babies, researchers report online May 22 in Proceedings of the National Academy of Sciences.

If humans ever embark on long-term space flights, we’ll need a way to reproduce. One potential hurdle (beyond the logistical challenges of microgravity) is the high amount of solar radiation in space — radiation exposure is 100 times as high on the International Space Station as on Earth. Those doses might cause damaging genetic mutations in banked eggs and sperm.
To test this possibility, Japanese researchers sent freeze-dried mouse sperm up to the space station, where the sperm spent nine months. When rehydrated back on Earth, the sperm showed some signs of DNA damage compared with earthly sperm.

But when the researchers used the space sperm to fertilize eggs in the lab and then injected the eggs into female mice, the mice birthed healthy pups that were able to have their own offspring. The researchers suspect that some of the initial DNA damage might have been repaired after fertilization.

If mouse sperm can survive a trip to space, perhaps human sperm can, too.

HAT-P 7b is a windy world. Stiff easterlies typically whip through the atmosphere of the distant exoplanet, but sometimes the powerful gales blow in surprisingly varied directions. Now, simulations of the planet’s magnetic field lines, illustrated here as a rainbow of scrawled marks, reveal that HAT-P 7b’s magnetic field influences the winds, even turning some into westerlies. The result, published May 15 in Nature Astronomy, could lead to a better understanding of the atmospheres of other exoplanets.
Known as a “hot Jupiter,” HAT-P 7b is a gas giant that orbits its star once every 2.2 Earth days. The exoplanet, located 1,043 light-years away, is also tidally locked: One side always faces toward its star while the other faces away. That orientation pushes temperatures to about 1,900° Celsius on the planet’s dayside compared with about 900° C on the nightside. Those extreme temperature differences tend to power strong easterly winds, according to an analysis of data from the Kepler satellite. But that analysis also revealed that over time the winds are surprisingly mercurial.

The magnetic field, which may be generated by the planet’s core, is connected to the winds because of high temperatures stripping electrons from atmospheric atoms of lithium, sodium and potassium, making them positively charged. Those particles then interact with the field, creating an electromagnetic force strong enough to disrupt the stout easterly winds, writes study author Tamara Rogers, an astrophysicist at Newcastle University in England.

In the image above, blue lines track strong magnetic field lines directed one way, while those in magenta trace powerful lines in the opposite direction. Weaker parts of the field lines are shown in green and yellow. The stronger the magnetic field, the wilder the winds — with the strongest lines completely reversing the direction the winds blow, Rogers concludes.

A monkey’s brain builds a picture of a human face somewhat like a Mr. Potato Head — piecing it together bit by bit.

The code that a monkey’s brain uses to represent faces relies not on groups of nerve cells tuned to specific faces — as has been previously proposed — but on a population of about 200 cells that code for different sets of facial characteristics. Added together, the information contributed by each nerve cell lets the brain efficiently capture any face, researchers report June 1 in Cell.
“It’s a turning point in neuroscience — a major breakthrough,” says Rodrigo Quian Quiroga, a neuroscientist at the University of Leicester in England who wasn’t part of the work. “It’s a very simple mechanism to explain something as complex as recognizing faces.”

Until now, Quiroga says, the leading explanation for the way the primate brain recognizes faces proposed that individual nerve cells, or neurons, respond to certain types of faces (SN: 6/25/05, p. 406). A system like that might work for the few dozen people with whom you regularly interact. But accounting for all of the peripheral people encountered in a lifetime would require a lot of neurons.

It now seems that the brain might have a more efficient strategy, says Doris Tsao, a neuroscientist at Caltech.

Tsao and coauthor Le Chang used statistical analyses to identify 50 variables that accounted for the greatest differences between 200 face photos. Those variables represented somewhat complex changes in the face — for instance, the hairline rising while the face becomes wider and the eyes becomes further-set.

The researchers turned those variables into a 50-dimensional “face space,” with each face being a point and each dimension being an axis along which a set of features varied.
Then, Tsao and Chang extracted 2,000 faces from that map, each linked to specific coordinates. While projecting the faces one at a time onto a screen in front of two macaque monkeys, the team recorded the activity in single neurons in parts of the monkey’s temporal lobe known to respond specifically to faces. All together, the recordings captured activity from 205 neurons.

Each face cell was tuned to one of the 50 axes previously identified, Tsao and Chang found. The rate at which each cell sent electrical signals was proportional to a given face’s coordinate position along an axis. But a cell didn’t respond to changes in features not captured by that axis. For instance, a cell tuned to an axis where nose width and eye size changed wouldn’t respond to changes in lip shape.
Adding together the features conveyed by each cell’s activity creates a picture of a complete face. And like a computer creating a full-color display by mixing different proportions of red, green and blue light, the coordinate system lets a brain paint any face in a spectrum.

“It was a total surprise,” Tsao says. Even when the faces were turned in profile, the same cells still responded to the same features.

Tsao and Chang were then able to re-create that process in reverse using an algorithm. When they plugged in the activity patterns of the 205 recorded neurons, the computer spat out an image that looked almost exactly like what they had shown the monkeys.

“People view neurons as black boxes,” says Ed Connor, a neuroscientist at Johns Hopkins University who wasn’t part of the study. “This is a striking demonstration that you can really understand what the brain is doing.”

Elsewhere in the brain, though, neurons don’t use this facial coordinate system. In 2005, Quiroga discovered individual neurons attuned to particular people in the hippocampus, a part of the brain involved in memory. He found, for instance, a single neuron that fired off messages in response to a photo of Jennifer Aniston or conceptually related images, like her name written out or a picture of her Friends costar Lisa Kudrow.

The new results fit well into that picture, Tsao and Quiroga agree. Tsao compares her system to a GPS for facial identity. “These cells are coding the coordinates. And you can use these coordinates for anything you want. You can build a specific lookup table that codes these into specific identities — like Barack Obama, or your mother.”

Quiroga’s hippocampal cells, just a few neural connections away, are like the output of that table — a sort of speed dial for people and concepts previously encountered.

The different coding strategies might be tied to differences in what these brain areas do. “When we remember things, we forget details but we remember concepts,” Quiroga says. But for telling faces apart, and especially for processing unfamiliar faces, “details are key.”

Take a trip to a black hole with Stephen Hawking as a guide, watch glowing bioluminescent earthworms wriggle away from predators and discover the fascinating mathematics of origami — all while cuddled up in front of a laptop. That’s the promise of the online streaming service CuriosityStream, which offers hefty doses of science for viewers who prefer fact-based documentaries over reality TV, sports and the political bickering that dominate today’s television programming.

CuriosityStream, which recently celebrated its second birthday, operates much like Netflix. With plans starting at $2.99 per month, users can browse more than 1,700 commercial-free programs covering science, technology, history and the arts. The service works on computers, mobile devices and streaming players such as Roku and Apple TV.
CuriosityStream aims to supplement the media diet of science-starved viewers. “When you look at television … there’s very little science on anymore,” says Steve Burns, CuriosityStream’s chief programming officer. Subscribers, he says, “crave the substance that they’ve been missing on TV for so long.”

Along with a slew of documentaries from the BBC and other public broadcasters, CuriosityStream offers more than 600 original programs that you won’t find anywhere else. One standout is David Attenborough’s Light on Earth, in which the naturalist takes viewers on an engaging survey of bioluminescent life, from flickering fireflies and luminous mushrooms to eerily glowing ocean creatures.

Another enjoyable original is Stephen Hawking’s Favorite Places, in which the famed physicist tours a black hole, exoplanet Gliese 832c, Saturn and other cosmic locales. Computer-generated imagery of the turbulent region around a black hole, for example, provides a brilliant visual background to Hawking’s explanations of relevant research. One episode is currently available, and two new ones are slated to go online later in the year.

Some shows are more engaging than others. Another original, The Hunt for Dark Matter, takes a deep dive into the technology behind the search for the invisible substance thought to pervade the universe. But the show will likely fall flat for many viewers, as its introduction lacks some of the background on the physics of dark matter that is necessary to grasp the relevance of the work.

CuriosityStream provides a wealth of options to choose from, including a variety of shorter shows, each 10 or 15 minutes long. With new programs added regularly, the service should provide enough binge-worthy fodder to keep even the most avid documentary lovers busy

Premature babies, who often develop jaundice because of an excess of bile pigment called bilirubin, can be saved from this dangerous condition by the use of fluorescent light.… The light alters the chemistry of bilirubin so it can be excreted with the bile. Exchange transfusion is the usual treatment when jaundice occurs but this drastic procedure carries a … risk of death. —Science News, June 17, 1967

Update
Preemies aren’t the only babies at risk for jaundice. About 60 percent of full-term infants also develop the condition. Severe cases can cause brain damage if untreated. But today, some researchers warn that light therapy, now widely used, may not work for babies whose bilirubin levels are very high. And studies have begun to suggest a link between the therapy and certain childhood cancers (SN Online: 1/30/15). Though the risk of developing cancer is small, doctors should be cautious about prescribing the treatment, researchers wrote in 2016 in Pediatrics.