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Scientists have found the first experimental evidence that an atomic nucleus can harbor bubbles.

The unstable isotope silicon-34 has a bubblelike center with a paucity of protons, scientists report October 24 in Nature Physics. This unusual “bubble nucleus” could help scientists understand how heavy elements are born in the universe, and help scientists find new, ultraheavy stable isotopes.

In their quirky quantum way, protons and neutrons in a nucleus refuse to exist in only one place at a time. Instead, they are spread out across the nucleus in nuclear orbitals, which describe the probability that each proton or neutron will be found in a particular spot. Normally, due to the strong nuclear force that holds the two types of particles together, nuclei have a fairly constant density in their centers, regardless of the number of protons and neutrons they contain. In silicon-34, however, some scientists predicted that one of the proton orbitals that fills the center of the nucleus would be almost empty, creating a bubble nucleus. But not all theories agreed. “This was the reason for doing the experiment,” says coauthor Olivier Sorlin, a nuclear physicist at the National Large Heavy Ion Accelerator, GANIL, in Caen, France. “Some people didn’t believe that it would exist.”
In pursuit of the bubble nucleus, the scientists smashed silicon-34 nuclei into a beryllium target, which knocked single protons out of the nuclei to create aluminum-33. The resulting aluminum-33 nuclei were in excited, or high-energy, states and quickly dropped down to a lower energy by emitting photons, or light particles. By observing the energy of those photons, Sorlin and colleagues could reconstruct the orbital of the proton that had been kicked out of the nucleus.

The scientists found that they ejected few protons from the central orbital that theorists had predicted would be empty. While the orbital can theoretically hold up to two protons, it held only 0.17 protons on average. In silicon-34, the central proton density is about half that of a comparable nucleus, the scientists calculated, after taking into account other central orbitals that contain normal numbers of protons. (The density of neutrons in silicon-34’s center, however, is normal.)
“What they are doing is extremely difficult,” says theoretical nuclear physicist Paul-Henri Heenen of the Université libre de Bruxelles in Belgium. Silicon-34 isn’t stable, he notes. It has a half-life of less than three seconds, making it a challenge to work with.
As protons are added to nuclei, they fill orbitals in a sequential manner, according to the energy levels of the orbitals. Silicon-34 is special — it has a certain “magic” number of protons and neutrons in its nucleus. There are a variety of such magic numbers, which enhance the stability of atomic nuclei. A magic number of protons means that the energy needed to boost a proton into the next orbital is particularly high. This explains the bubble’s origin. For a proton to jump into the unfilled central orbital, it needs significantly more energy. So silicon-34’s center remains sparsely populated.

“It’s an interesting paper and indeed provides evidence” for a bubble nucleus, says nuclear physicist Jiangming Yao of the University of North Carolina, Chapel Hill. But, he says, the evidence is “not direct,” because it relies on nuclear models to calculate density. To directly measure the density of protons will require using electrons to probe the inner workings of the nucleus.

Still, the research could help scientists understand the spin-orbit interaction, the interplay between a proton’s angular momentum in its orbital and its intrinsic angular momentum, or spin. The effect is important for keeping heavy nuclei stable. Figuring out the impact of that interaction in this unusual nucleus could help scientists better predict the potential location of the “island of stability,” a theorized region of the periodic table with heavy elements that may be stable for long periods of time (SN: 6/5/10, p. 26).

What’s more, a better grasp of the spin-orbit interaction could also help scientists learn how elements are forged in rare cosmic cataclysms such as the merging of two neutron stars. There, nuclei undergo a complex chain of reactions, swallowing up neutrons and undergoing radioactive decay. Modeling this process requires a precise understanding of the stability of various nuclei — a property affected by the spin-orbit interaction.

At the ripe old age of 3, my older daughter has begun flirting with falsehoods. So far, the few lies she has told have been comically bad and easy to spot. Her dad and I usually laugh at them with an amused, “Oh, yeah?” But now that I’ve stopped to consider, that strategy seems flawed.

While reporting a story on adult lying, I had the pleasure of talking with developmental psychologist Victoria Talwar of McGill University, who studies lying in children. I told her about an episode last week, in which I watched my older daughter swat my younger one. Instead of simply accepting reality and scolding her, my reaction was to question it further. “Did you just hit your sister?” After a pause, the guilty one offered a slightly confused “no.”

My accusatory question had created conditions ripe for this lie to be spawned. And now, as Talwar pointed out, I was dealing with two things: the hitting and the lie. “If you catch them in a transgression, just deal with the transgression,” she told me. “Don’t give them a chance to lie by asking a question you already know the answer to.”

Lying, it turns out, is actually a sign of something good happening in the developing brain. Dishonesty requires some mental heavy lifting, like figuring out what another person knows and how to use that information to your advantage. Many kids start experimenting with stretching the truth between ages 3 and 4. “In a way, it’s almost like they’re exercising a new ability,” Talwar says. “ And part of that is, ‘Mommy doesn’t know what I just did.’”

That thought sounds simple, but it’s actually quite profound. It means that a child is developing what scientists call theory of mind — the ability to understand the perspectives of other people and realize that those perspectives are sometimes different. It also means that a friend of mine who has put in years of hard work convincing her 5-year-old daughter that she is all-seeing and all-knowing may be out of luck soon. With a quickly solidifying theory of mind, her kid will wise up to her mom’s tall tale, if she hasn’t already.

For the rest of us parents who can’t maintain an elaborate charade like that, Talwar says the key is to create an environment that fosters truth-telling. “One of the most important ways to encourage honesty is to acknowledge it when you see it,” she says. If my daughter had answered yes to my ridiculous question, I should have thanked her for telling the truth before addressing the hitting. “Make sure they understand that you’ve appreciated that bit,” Talwar says.

Another strategy to minimize lies, as simple as it sounds, is to ask your kid to tell you the truth. Sweet little children, bless their hearts, just might comply, as a study from Talwar and colleagues suggests.
And remember, if you want your kid to value honesty, you should check yourself. One study found that children were more likely to lie after having been lied to. And lest you think you can skirt under their underdeveloped lie radars, consider a recent study. Children ages 6 to 11 were actually not terrible at detecting white lies. When watching a video of an adult or child saying that they thought a hunk of used, dingy soap was a good gift, or that a bad drawing of a person was actually good, children were about as good as adults in spotting fibs.

The result was interesting because it meant that children weren’t just swallowing adults’ lies, says study coauthor Michelle Eskritt of Mount St. Vincent University in Halifax, Canada. For these sorts of lies, kids weren’t just assuming that everyone was telling the truth, she says.

Now that my daughter is learning about honesty, we’ve been having some fun conversations about what the truth really is. These days she likes it when I make up stories that feature her telling elaborate whoppers. My lies about her lies really crack her up.

A quarter century after scientists proposed an idea that profoundly influenced the arc of Alzheimer’s research, they might finally find out whether they are correct. A new antibody drug called aducanumab appears to sweep the brain clean of sticky amyloid-beta protein. The drug may or may not become a breakthrough Alzheimer’s treatment — it’s too soon to say — but either way it will probably answer a key question: Have researchers been aiming at the right target?

According to the proposal, called the amyloid hypothesis, Alzheimer’s disease, estimated to affect more than 5 million people in the United States alone, is caused by abnormal buildup of A-beta protein in the brain. The buildup chokes vital brain areas and destroys nerve cells. Despite amassing much support in recent decades, the proposal hasn’t managed to shake off its detractors. Aducanumab offers a seemingly reliable and safe way to lower A-beta levels and thus test the amyloid hypothesis.
Over the course of a year, aducanumab entered the brains of people with early Alzheimer’s disease and cleared out the A-beta, scientists reported in September in Nature (SN: 10/1/16, p. 6). The trial was small — only 165 people. Yet in these people’s brains, amyloid-beta clearly declined. The higher the dose, the more A-beta cleanup.

There were hints that people on higher doses of the drug had cognitive improvements, too. If confirmed in larger studies, those cognitive benefits “would be a game changer for the field,” says Alzheimer’s researcher Eric Reiman of the Banner Alzheimer’s Institute in Phoenix. But those results “need to be treated agnostically for now,” at least until the larger studies currently under way are completed, he cautions.
There is already strong evidence that A-beta is a disease culprit: Rare genetic mutations in genes related to A-beta almost always come with Alzheimer’s, an observation that has been confirmed in mice. A-beta is toxic to nerve cells in dishes, damaging their communication abilities before eventually killing the cells outright. “All the basic science work and natural history work supports it,” says neuroscientist John Hardy of University College London, who is among those who proposed the amyloid hypothesis.
Yet contradictions exist. Cognitively healthy people have been found with A-beta accumulation in their brain (SN: 12/10/16, p. 13). And so far, scientists have found only a weak correlation between A-beta plaques and cognition, results that have led some scientists to look elsewhere — to inflammation, overzealous pruning of brain cell connections called synapses and changes to the protein tau, which is known to accumulate inside nerve cells in people with Alzheimer’s. Each of these cellular processes has also been implicated as a driver of the disease.

Identifying the true cause of Alzheimer’s is difficult because all of these processes are closely related and occur simultaneously, making it nearly impossible to study their effects in isolation. What’s more, many of the key changes might happen years, or even decades, before symptoms begin to appear. Hardy concedes that in the years since he and others introduced the amyloid hypothesis, scientists have struggled to put together a full picture of Alzheimer’s. “It is tougher than we all thought it would be,” he says.

There won’t be clear answers for several years yet. In August of 2015, larger clinical trials of aducanumab began enrolling patients around the world with the goal of finishing by 2022. As more people with Alzheimer’s are tested, researchers hope to see obvious signs of mental improvement that track reductions in brain A-beta. It’s possible that aducanumab will lower A-beta in the brain yet fail to bring meaningful improvements in symptoms. Such a result might appear to be a strike against the amyloid hypothesis, a contradiction that could prod some researchers to explore other ideas more deeply. Either way, people with Alzheimer’s and their loved ones are waiting anxiously.

Immune cells in a malaria-transmitting mosquito sense the invading parasites and deploy an army of tiny messengers in response. These couriers help turn on a mosquito’s defenses, killing off the parasites, a new study suggests.

This more detailed understanding of the mosquito immune system, published January 20 in Science Immunology, might help scientists design new ways to combat malaria, which infects more than 200 million people per year.

“If we understand how the mosquito reduces the parasite to begin with, we hope we can boost these mechanisms to completely eliminate these parasites [in mosquitoes],” says Kristin Michel, an insect immunologist at Kansas State University in Manhattan who wasn’t part of the study.
Different parasites in the Plasmodium genus cause malaria. The disease is spread by certain Anopheles mosquitoes. These mosquitoes have natural defenses against Plasmodium that keep them from being overrun with the parasites when feeding on an infected person’s blood. But malaria transmission still occurs, because some Plasmodium species are particularly skilled at evading mosquito immune systems.

Previous research has shown that hemocytes, the insect equivalent of white blood cells, help mosquitoes fight off pathogens. Carolina Barillas-Mury and her colleagues at the National Institute of Allergy and Infectious Diseases in Rockville, Md., injected Anopheles gambiae mosquitoes — a primary spreader of malaria in sub-Saharan Africa — with a dye that stained their hemocytes. Those mosquitoes snacked on mice infected with a rodent version of malaria. Then the scientists watched the dyed hemocytes’ response.
Hemocytes that detected certain chemical fingerprints left by the parasites began to self-destruct. These dying hemocytes released plumes of tiny vesicles that then activated the mosquito’s defenses against the parasite, the researchers found. The vesicles triggered a protein called TEP1 to take down the parasite. Scientists already knew that TEP1 is an important part of mosquitoes’ immune response against Plasmodium parasites, but it wasn’t clear how the protein was called into action. Without the vesicles, TEP1 didn’t target the parasites.
Barillas-Mury and colleagues don’t know exactly what the microvesicles contain. But she suspects they carry messenger molecules that jump-start TEP1 and other proteins involved in this immune response.

This type of response “is a very powerful defense system because it can make holes in the parasite and kill it,” says Barillas-Mury. “You want it to be active, but in the right place and at the right time.” Plasmodium parasites set up shop in different places in the mosquito gut depending on their life stage. Microvesicles, much smaller than the hemocytes, can more easily move through different gut compartments to trigger a localized immune response right where the parasite is.

The researchers eventually hope to use their understanding of the mosquito immune response to develop new ways to stop malaria. They’re interested in creating a vaccine that prevents mosquitoes that bite an infected person from passing along the parasite. Such a vaccine could be used in combination with others under development that would prevent people infected with the parasite from becoming sick, Barillas-Mury says.

A strange X-ray signal has popped up again in new measurements, raising hopes that it could be a sign of dark matter.

Data from NASA’s Chandra X-ray Observatory reveal an excess of X-rays at a particular energy, creating a bump on a plot, scientists report online at arXiv.org on January 29. The X-ray “line,” as it is known, could reveal the presence of dark matter — an unknown substance that scientists believe constitutes most of the matter in the cosmos.
While the X-ray line has been found previously using several different telescopes, some searches have come up empty (SN: 9/3/16, p. 17). The new observation strengthens the case that the odd feature is real, and eliminates some possible mundane explanations.

“This is a very exciting thing,” says astrophysicist Nico Cappelluti of Yale University, a coauthor of the report. “This is another measurement that sees the line in another direction.”

The new analysis uses data taken when the telescope was observing deep space, rather than pointing at a particular cluster of galaxies. So if the signal indicated dark matter, it would be due to particles in the region surrounding the Milky Way, known as its halo. When hypothetical dark matter particles called sterile neutrinos decay, they could produce X-rays at the energy of the line, about 3,500 electron volts (SN Online: 12/11/15).

Cappelluti and colleagues found that the relative intensity of the line in the halo and the line previously found at the center of the Milky Way was consistent with the expected variation in concentration of dark matter in various parts the galaxy.

Dark matter isn’t the only possible explanation — standard physics might also be able to explain the line. “There’s definitely a lot of debate,” says Shunsaku Horiuchi, an astroparticle physicist at Virginia Tech in Blacksburg who was not involved with the new work. The line “looks like it’s real, but then I don’t know if it’s dark matter or some atomic physics.”
Although there’s still a small chance that the result could be a statistical fluke, the analysis eliminates some other possible explanations. Scientists had proposed that the line could be the result of sulfur ions grabbing an electron from hydrogen atoms in space, but that process couldn’t explain the new data, Cappelluti and colleagues concluded. Likewise, a quirk of the telescope itself couldn’t explain the line, they determined.

“It’s kind of getting other people excited,” says Horiuchi.

After flying more than 10,000 kilometers from South America to the Arctic, male pectoral sandpipers should be ready to rest their weary wings. But once the compact shorebirds arrive at a breeding ground in Barrow, Alaska, each spring, most keep going — an average of about 3,000 extra kilometers.

Scientists thought males, which mate with multiple females, stayed put at specific sites around the Arctic to breed. Instead, in a study of 120 male pectoral sandpipers in Barrow, most flitted all across the region looking for females. One bird flew a whopping 13,045 kilometers more after arriving, researchers report online January 9 in Nature.
“We had no clue that they range over such a wide area,” says study coauthor Bart Kempenaers, a behavioral ecologist at the Max Planck Institute for Ornithology in Seewiesen, Germany. To track the birds, the researchers placed satellite transmitters on 60 males in 2012 and another 60 in 2014.

“It doesn’t seem to be very tough for them to do these flights,” Kempenaers says. Competition for a mate, however, is cutthroat. In Barrow, just a few males sire the majority of offspring each year. The new work shows males visited as many as 24 potential breeding sites over four weeks, perhaps to boost their chances of reproducing.

Some had better stamina than luck. Kempenaers told of one male’s 2,000-kilometer Arctic odyssey: Once the bird reached Barrow, it flew north over the Arctic Ocean before turning around and landing just 300 kilometers from where it started. “There’s nothing northwards. There is only the [North] Pole, no land,” he says.

A new scorecard, devised by analyzing Ebola patients from the most recent outbreak in West Africa, may help doctors quickly decide who needs additional care to survive the virus in future epidemics.

In the latest outbreak, which raged in Guinea, Liberia and Sierra Leone from 2014 to 2016, 28,616 people were infected with virus and 11,310 people died. Doctors might be able to improve the odds of surviving by looking for a few warning signs in people who need to be treated more intensively, Mary-Anne Hartley, of the international charity GOAL Global and the University of Lausanne in Switzerland, and colleagues report February 2 in PLOS Neglected Tropical Diseases.
“It can be very difficult to avoid bias when choosing which Ebola patient should be given extra care when you have limited time and resources,” Hartley says. “Should it be that sweet 7-year-old girl in the corner with a bad cough or the really athletic 45-year-old man who was a bit confused earlier? Our score suggests that it should be the latter.”

Top risk factors for dying from Ebola:
High viral load — Patients with lots of virus in their blood were 12.6 times as likely to die as those with a low viral load.
Age — Children under 5 were 5.4 times as likely to die as were people between 5 and 25; people over age 45 were 11.6 times as likely to die.
Disorientation — The symptom was associated with more than 94 percent of Ebola fatalities and increased the risk of dying by 13.1 times.
Hiccups
Diarrhea
Red, inflamed eyes
Labored breathing or shortness of breath
Muscle pain
Delayed treatment — The risk of dying increased 12 percent each day an infected person put off treatment for the first 10 days after symptoms started.

Astronomers may have spotted some of the earliest stardust ever created in the cosmos.

Astrophysicist Nicolas Laporte of University College London and colleagues detected the dust in a galaxy seen as it was when the universe was only 600 million years old. “We are probably seeing the first stardust of the universe,” Laporte says. The observations, published online March 8 in the Astrophysical Journal Letters, could help astronomers learn more about an early period known as cosmic reionization, when ultraviolet radiation stripped electrons from hydrogen atoms.
“Dust is ubiquitous in nearby and more distant galaxies, but has, until recently, been very difficult to detect in the very early universe,” says University of Edinburgh astrophysicist Michal Michalowski, who was not involved in the study. “This paper presents the most distant galaxy for which dust has been detected.”

The galaxy, called A2744_YD4, lies behind a galaxy cluster called Abell 2744. That cluster acts as a gravitational lens, magnifying and brightening the distant galaxy’s light by about a factor of two. Laporte and colleagues observed the galaxy with ALMA, the Atacama Large Millimeter/submillimeter Array in Chile, which revealed the dust.
Dust in such a remote galaxy comes from supernova explosions of massive stars that were among the earliest stars in the universe. Astronomers estimate the first stars formed around 400 million years after the Big Bang, which occurred 13.8 billion years ago. Laporte and colleagues estimate that A2744_YD4’s dust, at 600 million years after the Big Bang, weighs in at about 6 million times the mass of the sun. “This means that supernova explosions are able to produce large amounts of dust very quickly,” Michalowski says.
Laporte and colleagues also detected positively charged, or ionized, oxygen atoms and a signature of hydrogen, which suggest the galaxy’s gas is ionized.
Cosmic reionization completely rebooted the universe so that ionized rather than neutral atoms pervaded space. Understanding this switch from neutral to ionized atoms gives clues to how stars and galaxies arose in the early universe. Finding ionized oxygen in such a remote galaxy “provides evidence that at least a fraction of cosmic reionization was caused by galaxies like A2744_YD4,” Michalowski says.

Until now, astronomers have been charting the early history of galaxies by counting them and looking at their colors, notes study coauthor Richard Ellis, a cosmologist currently on leave from University College London at the European Southern Observatory. Spotting dust in the distant universe offers a new route to determine when the earliest galaxies first formed, based on the abundances of oxygen, silicon and other heavier elements that they contain. Fewer heavy elements would point to younger and younger galaxies.

The detection of ionized oxygen could also hint that a black hole lurks at the center of A2744_YD4. Ionized oxygen, seen by the signal it emits in millimeter wavelengths, may be difficult to generate from young hot stars alone. Another strong source of ionizing radiation, such as a black hole, may be needed to account for the signature. “Unfortunately with only one emission line we cannot, for sure, claim there’s a black hole in A2744_YD4,” Ellis says.

Sea ice skylights formed by warming Arctic temperatures increasingly allow enough sunlight into the waters below to spur phytoplankton blooms, new research suggests. Such conditions, probably a rarity more than two decades ago, now extend to roughly 30 percent of the ice-covered Arctic Ocean during July, researchers report March 29 in Science Advances.

The microscopic critters need plenty of sunlight to thrive, so scientists were stunned by the discovery of a sprawling bloom below the normally sun-blocking Arctic ice in July 2011 (SN: 7/28/12, p. 17). Satellites can’t peek below the ice, though, so scientists at the time didn’t know whether the bloom was an oddity or representative of a shift in the Arctic environment.

Harvard University oceanographer Christopher Horvat and colleagues created a computer simulation of sea ice conditions from 1986 through 2015. Warming temperatures have thinned the ice, the researchers found, and increased the prevalence of meltwater pools on top of the ice that allow more light to pass through than bare or snow-covered ice.

Whether blooms are in fact more commonplace under the ice remains unclear, though, because the study didn’t consider whether there would be enough nutrients such as nitrogen and iron for budding blooms. If more blooms are lurking in the Arctic Ocean, they may already be dramatically reshaping the Arctic ecosystem. A boost in phytoplankton could alter marine food webs as well as soak up more planet-warming carbon dioxide from the environment.

Big bloom
Increasingly large swaths of the ice-covered Arctic Ocean allow enough light into the waters below to support phytoplankton blooms, new research suggests. Green regions indicate bloom-friendly conditions in July over the last few decades, with darker shades representing longer duration.

Gravel devil
GRAV-uhl DEV-uhl n.
A whirlwind containing gravel-sized debris

Towering, crystal-filled twisters periodically swirl in a valley nestled between two volcanoes in the Andes Mountains, newly reported observations show. The odd weather events are the first record of large pieces of gravel efficiently moving across a landscape by suspension in air.

Geologist Kathleen Benison of West Virginia University in Morgantown spotted the whirlwinds during an expedition in 2007 to an otherworldly region of northern Chile. There, gypsum crystals form from evaporating volcanic pools of salty, acidic water. When the pools dry, exposing the crystals within, whirlwinds as big as half a kilometer across can sweep the crystals aloft, Benison reports online March 15 in Geology. She saw storms of crystals travel as far as five kilometers before dropping their payloads into large, dunelike piles.
Over time the far-flung crystals, some as long as 27 centimeters (which geologists still classify as gravel), meld together into a massive hunk. If found in the rock record, such crystal conglomerations could help geologists identify where strong whirlwinds howled long ago, Benison proposes.