The last of a group of dense minerals that make up much of Earth’s crust and upper mantle has been found tucked inside a meteorite that slammed into Australia 135 years ago. The newly discovered mineral, a variety of majorite, is potentially abundant in sinking tectonic plates and could help illuminate the behavior of the deep Earth, its discoverers say.
Each identical component of this mineral contains 32 magnesium atoms, 32 silicon atoms and 96 oxygen atoms arranged in a distorted cube. Natural samples of MgSiO3 tetragonal garnet, the mineral’s scientific moniker, had eluded scientists since the mineral was first artificially produced in 1985. Naotaka Tomioka, a mineralogist at the Kochi Institute for Core Sample Research in Japan, and colleagues discovered 0.5-micrometer-wide grains of the mineral in a slice of the 19th century meteorite. While many minerals found in meteorites form when slamming into Earth, the new mineral formed in space when two asteroids collided at a relative speed of about 2 kilometers per second, the researchers report online March 25 in Science Advances.
One challenge remains for the researchers: As discoverers of the mineral, they now get to name it.
Financial health takes a hit among people who smoke a lot of marijuana from adolescence into young adulthood, even if they don’t get hooked on the drug, researchers say.
The more years that individuals smoke pot four or more days a week, the more likely they are to experience serious money problems, say social epidemiologist Magdalena Cerdá of the University of California, Davis and her colleagues. Cash woes include defaulting on credit card payments, struggling to pay for food and rent and going on welfare. In a representative sample of 947 New Zealanders studied from birth to age 38, adult economic and social problems — which also include a fall from middle-class status, stealing money at work and domestic violence — occurred about equally among regular marijuana and alcohol users, the scientists report March 22 in Clinical Psychological Science. Of 29 persistent pot smokers who grew up in middle-class families, 15 experienced downward social mobility, versus only 23 of 160 middle-class peers who never used marijuana.
Participants who consistently qualified as dependent on marijuana after age 18 encountered the worst money troubles over time, even exceeding those of alcoholic peers.
These findings don’t prove that regular pot smoking caused Kiwis’ financial difficulties, the investigators caution. But the association between marijuana and money troubles remained after accounting for childhood poverty, IQ, teenage delinquency and depression, impulsiveness, self-reported motivation to succeed in life, pot-related criminal convictions and abuse of alcohol and other drugs on top of frequent marijuana use.
Thousands of national parks have been established around the world to preserve wildlife. But towns, farms, ranches and roads have grown up around many of these parks, creating islands of wilderness in a sea of humanity. If the creatures inside are to thrive, they need ways to travel between the islands, contends “Wild Ways,” a new documentary from the TV series NOVA.
Isolation can be especially troublesome for large predators, such as lions, that live alone or in small groups. In some areas of Africa, lions can move between populations to avoid inbreeding. But some lions, such as the few in Tanzania’s Ngorongoro Crater, are cut off from other groups. In such populations, cubs are born smaller, die younger and are more susceptible to disease. And drought or overhunting could easily wipe them out, the show notes. To connect these smaller populations, conservationists are now building wildlife corridors between parks. One of the most ambitious projects is the Yellowstone to Yukon Conservation Initiative, which aims to create connections between grizzly bears in the Canadian Arctic and the western United States. Other large wildlife corridors are being planned in Central America, eastern Australia and the Himalayas. But there are often roadblocks. It can be difficult to persuade people to spend money on wildlife, and it can be even harder when those animals kill livestock or humans.
“It is important that we provide incentives for local communities, in particular, who should now look at wildlife as some form of economic asset to themselves,” says Simon Munthali of the Kavango-Zambezi Transfrontier Conservation Area, which is attempting to connect parks in five countries across southern Africa. With the right incentives, people will be more accepting of wildlife moving across land and may even benefit from it, he says in the documentary. Botswana, for instance, has developed a large ecotourism industry that provides jobs and money for local people, motivating animal protection.
The documentary is a bit too optimistic about the removal of hurdles that stand in the path of wildlife corridors, especially in the American West, where there is ongoing debate about how to manage public lands. And then there is the question of whether these corridors can be created fast enough to save the world’s dwindling animal populations. But, as Michael Soulé, one of the founders of the field of conservation biology, says: “It’s our last chance to protect the diversity of life on Earth.” “Wild Ways” makes a convincing case that we should be willing to try.
Parasitic worms may hold the secret to soothing inflamed bowels.
In studies of mice and people, parasitic worms shifted the balance of bacteria in the intestines and calmed inflammation, researchers report online April 14 in Science. Learning how worms manipulate microbes and the immune system may help scientists devise ways to do the same without infecting people with parasites.
Previous research has indicated that worm infections can influence people’s fertility (SN Online: 11/19/15), as well as their susceptibility to other parasite infections (SN: 10/5/13, p. 17) and to allergies (SN: 1/29/11, p. 26). Inflammatory bowel diseases also are less common in parts of the world where many people are infected with parasitic worms. P’ng Loke, a parasite immunologist at New York University School of Medicine, and colleagues explored how worms might protect against Crohn’s disease. The team studied mice with mutations in the Nod2 gene. Mutations in the human version of the gene are associated with Crohn’s in some people.
The mutant mice develop damage in their small intestines similar to that seen in some Crohn’s patients. Cells in the mice’s intestines don’t make much mucus, and more Bacteroides vulgatus bacteria grow in their intestines than in the guts of normal mice. Loke and colleagues previously discovered that having too much of that type of bacteria leads to inflammation that can damage the intestines. In the new study, the researchers infected the mice with either a whipworm (Trichuris muris) or a corkscrew-shaped worm (Heligmosomoides polygyrus). Worm-infected mice made more mucus than uninfected mutant mice did. The parasitized mice also had less B. vulgatus and more bacteria from the Clostridiales family. Clostridiales bacteria may help protect against inflammation. “Although we already knew that worms could alter the intestinal flora, they show that these types of changes can be very beneficial,” says Joel Weinstock, an immune parasitologist at Tufts University Medical Center in Boston.
Both the increased mucus and the shift in bacteria populations are due to what’s called the type 2 immune response, the researchers found. Worm infections trigger immune cells called T helper cells to release chemicals called interleukin-4 and interleukin-13. Those chemicals stimulate mucus production. The mucus then feeds the Clostridiales bacteria, allowing them to outcompete the Bacteroidales bacteria. It’s still unclear how the mucus encourages growth of one type of bacteria over another, Loke says.
Blocking interleukin-13 prevented the mucus production boost and the shift in bacteria mix, indicating that the worms work through the immune system. But giving interleukin-4 and interleukin-13 to uninfected mice could alter the mucus and bacterial balance without worms’ help, the researchers discovered.
Loke and colleagues also wanted to know if worms affect people’s gut microbes. So the researchers took fecal samples from people in Malaysia who were infected with parasitic worms.
After taking a deworming drug, the people had less Clostridiales and more Bacteriodales bacteria than before. That shift in bacteria was associated with a drop in the number of Trichuris trichiura whipworm eggs in the people’s feces, indicating that getting rid of worms may have negative consequences for some people.
Having data from humans is important because sometimes results in mice don’t hold up in people, says Aaron Blackwell, a human biologist at the University of California, Santa Barbara. “It’s nice to show that it’s consistent in humans.”
Worms probably do other things to limit inflammation as well, Weinstock says. If scientists can figure out what those things are, “studying these worms and how they do it may very well lead to the development of new drugs.”
Someone new has entered my life — a tiny, ear-splitting maniac who inchworms across the entire living room on her arched, furious back. My 3-year-old daughter hasn’t thrown temper tantrums, but to our surprise, her 1½-year-old sister is happy to fill that void.
Last week, my pleasant yet firm, “No, you can’t eat the stick of butter,” sent my toddler down to the floor, where she shrieked and writhed for what felt like an eternity. I’ve learned that talking to her or even looking at her added fuel to her fiery fit, so there’s not much to do other than ride out the storm.
It’s awful, of course, to see how miserable a kid is in the throes of a tantrum. And the fact that she can’t fully express her little heart with words just makes it worse. Adults, with our decades of practice, have trouble wrangling big emotions, so it’s no surprise that children can be easily overcome.
Because tantrums offer glimpses into the expression of strong emotions, they are a “compelling phenomenon for scientific study,” psychologist James Green of the University of Connecticut and colleagues wrote in a 2011 paper in the journal Emotion. I agree, by the way, but I am also supremely relieved that I am not the one studying them. To catch tantrums in their native habitat, the scientists outfitted 13 preschoolers with special onesies with microphones sewn into the front, and waited for the kids to lose their minds.
This masochistic experiment caught 24 emotional tsunamis in 2- to 3-year olds. By analyzing the sounds contained in them, the researchers could deconstruct tantrums into five types of noises, each with its own with distinct auditory quality. At the most intense end of the acoustic spectrum was the screams. The acoustical assault slowly eased as sounds became less energetic yells, cries, whines and fusses.
Screams and yells are more similar to each other, forming a group of sounds that often mean anger, the authors suggest. Cries, fusses and whines also group together, representing sadness. This excruciatingly detailed breakdown hints that tantrums have underlying structures. Sadly, the results do not tell us parents how to head off tantrums in the first place.
Simple preventives like keeping kids well-fed, rested and comfortable can stave off some meltdowns, but beyond those basics, we may be out of luck. My somewhat fatalistic view is that when faced with unruly emotions, some kids just can’t help themselves. After all, my older daughter doesn’t throw tantrums, at least not yet. Yet I do suspect that my own behavior is involved. An illuminating study in the August 2013 Journal of Behavioral Medicine hints that parents of tantrum-prone kids can curb tantrums (or at least their perceptions of tantrums) by somehow changing their own behavior. After eight days of giving their kids “flower essence,” an inert substance sold as a tantrum reducer, parents reported fewer outbursts from their kids. The effect was “placebo by proxy,” meaning that the parents’ beliefs in the product — and possibly their subsequent behavior — may have transferred to their kids. So just believing that their kid is going to throw fewer tantrums led the parents to believe that their kid threw fewer tantrums.
The study couldn’t say whether tantrums actually decreased or parents just perceived fewer of them. But really, either one would be an improvement in our house. Either that or my toddler is going to eat a lot of butter.
Before anybody even had a computer, Claude Shannon figured out how to make computers worth having.
As an electrical engineering graduate student at MIT, Shannon played around with a “differential analyzer,” a crude forerunner to computers. But for his master’s thesis, he was more concerned with relays and switches in electrical circuits, the sorts of things found in telephone exchange networks. In 1937 he produced, in the words of mathematician Solomon Golomb, “one of the greatest master’s theses ever,” establishing the connection between symbolic logic and the math for describing such circuitry. Shannon’s math worked not just for telephone exchanges or other electrical devices, but for any circuits, including the electronic circuitry that in subsequent decades would make digital computers so powerful.
It’s now conveniently a good time to celebrate Shannon’s achievements, on the occasion of the centennial of his birth (April 30) in Petoskey, Michigan, in 1916. Based on the pervasive importance of computing in society today, it wouldn’t be crazy to call the time since then “Shannon’s Century.”
“It is no exaggeration,” wrote Golomb, “to refer to Claude Shannon as the ‘father of the information age,’ and his intellectual achievement as one of the greatest of the twentieth century.”
Shannon is most well-known for creating an entirely new scientific field — information theory — in a pair of papers published in 1948. His foundation for that work, though, was built a decade earlier, in his thesis. There he devised equations that represented the behavior of electrical circuitry. How a circuit behaves depends on the interactions of relays and switches that can connect (or not) one terminal to another. Shannon sought a “calculus” for mathematically representing a circuit’s connections, allowing scientists to be able to design circuits effectively for various tasks. (He provided examples of the circuit math for an electronic combination lock and some other devices.)
“Any circuit is represented by a set of equations, the terms of the equations corresponding to the various relays and switches in the circuit,” Shannon wrote. His calculus for manipulating those equations, he showed, “is exactly analogous to the calculus of propositions used in the symbolic study of logic.”
As an undergraduate math (and electrical engineering) major at the University of Michigan, Shannon had learned of 19th century mathematician George Boole’s work on representing logical statements by algebraic symbols. Boole devised a way to calculate logical conclusions about propositions using binary numbers; 1 represented a true proposition and 0 a false proposition. Shannon perceived an analogy between Boole’s logical propositions and the flow of current in electrical circuits. If the circuit plays the role of the proposition, then a false proposition (0) corresponds to a closed circuit; a true proposition (1) corresponds to an open circuit. More elaborate math showed how different circuit designs would correspond to addition or multiplication and other features, the basis of the “logic gates” designed into modern computer chips.
For his Ph.D. dissertation, Shannon analyzed the mathematics of genetics in populations, but that work wasn’t published. In 1941 he began working at Bell Labs; during World War II, he wrote an important (at the time secret) paper on cryptography, which required deeper consideration of how to quantify information. After the war he developed those ideas more fully, focusing on using his 1s and 0s, or bits, to show how much information could be sent through a communications channel and how to communicate it most efficiently and accurately.
In 1948, his two papers on those issues appeared in the Bell System Technical Journal. They soon were published, with an introductory chapter by Warren Weaver, in a book titled The Mathematical Theory of Communication. Today that book is regarded as the founding document of information theory.
For Shannon, communication was not about the message, or its meaning, but about how much information could be communicated in a message (through a given channel). At its most basic, communication is simply the reproduction of a message at some point remote from its point of origin. Such a message might have a “meaning,” but such meaning “is irrelevant to the engineering problem” of transferring the message from one point to another, Shannon asserted. “The significant aspect is that that actual message is one selected from a set of possible messages.” Information, Shannon decided, is a measure of how much a communication reduces the ignorance about which of those possible messages has been transmitted.
In a very simple communication system, if the only possible messages are “yes” and “no,” then each message (1 for yes, 0 for no) reduces your ignorance by half. By Shannon’s math, that corresponds to one bit of information. (He didn’t coin the term “bit” — short for binary digit — but his work established its meaning.) Now consider a more complicated situation — an unabridged English dictionary, which should contain roughly half a million words. One bit would correspond to a yes-or-no that the word is in the first half of the dictionary. That reduces ignorance, but not very much. Each additional bit would reduce the number of possible words by half. Specifying a single word from the dictionary (eliminating all the ignorance) would take about 19 bits. (This fact is useful for playing the game of 20 Questions — just keep asking about the secret word’s location in the dictionary.)
Shannon investigated much more complicated situations and devised theorems for calculating information quantity and how to communicate it efficiently in the presence of noise. His math remains central to almost all of modern digital technology. As electrical engineer Andrew Viterbi wrote in a Shannon eulogy, Shannon’s 1948 papers “established all the key parameters and limits for optimal compression and transmission of digital information.”
Beyond its practical uses, Shannon’s work later proved to have profound scientific significance. His math quantifying information in bits borrowed the equations expressing the second law of thermodynamics, in which the concept of entropy describes the probability of a system’s state. Probability applied to the ways in which a system’s parts could be arranged, it seemed, mirrored the probabilities involved in reducing ignorance about a possible message. Shannon, well aware of this connection, called his measure entropy as well. Eventually questions arose about whether Shannon’s entropy and thermodynamic entropy shared more than a name.
Shannon apparently wasn’t sure. He told one writer in 1979 that he thought the connection between his entropy and thermodynamics would “hold up in the long run” but hadn’t been sufficiently explored. But nowadays a deep conceptual link shows up not only between Shannon’s information theory and thermodynamics, but in fields as diverse as quantum mechanics, molecular biology and the physics of black holes. Shannon’s understanding of information plays a central role, for instance, in explaining how the notorious Maxwell’s demon can’t violate thermodynamics’ second law. Much of that work is based on Landauer’s principle, the requirement that energy is expended when information is erased. In developing that principle, Rolf Landauer (an IBM physicist) was himself influenced both by Shannon’s work and the work of Sadi Carnot in discerning the second law in the early 19th century.
Something Shannon and Carnot had in common, Landauer once emphasized to me, was that both discovered mathematical restrictions on physical systems that were independent of the details of the system. In other words, Carnot’s limit on the efficiency of steam engines applied to any sort of engine, no matter what it was made of or how it was designed. Shannon’s principles specifying the limits on information compression and transmission apply no matter what technology is used to do the compressing or sending. (Although in Shannon’s case, Landauer added, certain conditions must be met.)
“They both find limits for what you can do which are independent of future inventions,” Landauer told me. That is, they have grasped something profound about reality that is not limited to a specific place or time or thing.
So it seems that Shannon saw deeply not only into the mathematics of circuits, but also into the workings of nature. Information theorist Thomas Cover once wrote that Shannon belongs “in the top handful of creative minds of the century.” Some of Shannon’s original theorems, Cover noted, were not actually proved rigorously. But over time, details in the sketchy proofs have been filled in and Shannon’s intuitive insights stand confirmed. “Shannon’s intuition,” Cover concluded, “must have been anchored in a deep and natural theoretical understanding.” And it seems likely that Shannon’s intuition will provide even more insights into nature in the century ahead.
A decent office scanner has beaten X-ray blasts from multimillion-dollar synchrotron setups in revealing how air bubbles kill plant leaves during drought.
Intricate fans and meshes of plant veins carrying water are “among the most important networks in biology,” says Timothy Brodribb of the University of Tasmania in Hobart, Australia. When drought weakens the water tension in veins, air from plant tissues bubbles in, killing leaves much as bubble embolisms and clots in blood vessels can kill human tissue. As climate change and population growth increase risks of water shortage, Brodribb and other researchers are delving into the details of what makes some plants more resistant than others to drought. The high energy of X-rays destroys delicate leaf tissue. So, based on a chat with microfluidics specialist Philippe Marmottant of the French National Center for Scientific Research, Brodribb tried repeatedly scanning a leaf with a light source below it to reveal darkening lines as air bubbles shot through the veins. A microscope or scanner proved perfect. Tracked this way, an invasion of killer bubbles “looks like a lightning storm,” he says.
He was surprised to see that bigger veins, despite their robust looks, fail before tiny ones (blue indicates earliest failures; red, the latest), as seen in an oak leaf (lower right) and Pteris fern (top). And networks in ferns with simpler branching patterns, as in the Adiantum ferns at bottom left, crash quickly.
This system of visualizing plant plumbing gave better resolution than expensive and elaborate X-ray techniques had, Brodribb, Marmottant and Diane Bienaimé report online April 11 in the Proceedings of the National Academy of Sciences.
Arabian camels (Camelus dromedarius) have trekked across ancient caravan routes in Asia and Africa for 3,000 years. But it’s unclear how camels’ domestication has affected their genetic blueprints.
To find out, Faisal Almathen of King Faisal University in Saudi Arabia and his colleagues combed through the DNA of 1,083 modern camels and ancient remains of wild and domesticated camels found at archaeological sites going back to 5000 B.C.
Camels run high on genetic diversity thanks to periodic restocking from now-extinct wild populations in the centuries after their domestication, the team reports May 9 in the Proceedings of the National Academy of Sciences. Travel on human caravan routes also created a steady flow of genes between different domesticated populations, except in a geographically isolated group in East Africa. That diversity may give some camel populations a leg up in adapting to future changes in climate, the authors suggest.
Something catapulted a pair of stars from the outer rim of our galaxy, but astronomers aren’t sure what. A binary star known as PB 3877 is rocketing away at about 2 million kilometers per hour — possibly fast enough to escape the galaxy’s gravitational pull — and all the usual explanations for such speedy stars fall short. Astrophysicist Péter Németh of the University of Erlangen-Nuremberg in Germany and colleagues report the discovery in the April 10 Astrophysical Journal Letters.
Many galactic escapees get kicked out after a close brush with the supermassive black hole in the Milky Way’s center. But PB 3877, first noticed in 2011 and currently about 18,000 light-years away in the constellation Coma Berenices, has been nowhere near that behemoth. A supernova could be responsible; it has happened before (SN Online: 3/5/15). But PB 3877 is two stars traveling together. A supernova would have torn the two apart. Németh and colleagues propose that the duo may be left over from a smashup between the Milky Way and a smaller galaxy. If that’s the case, then there might be others like PB 3877 lurking in the galactic outskirts.
Zapping Zika As Zika virus spreads, researchers are racing to find Zika-carrying mosquitoes’ Achilles’ heel, Susan Milius reported in “Science versus mosquito” (SN: 4/2/16, p. 30). Some approaches include genetic sterilization so mosquitoes can’t reproduce and infecting them with bacteria to decrease their disease-spreading power.
One reader had another suggestion. “Maybe we could just secure some wilderness areas for birds and bats,” Kurt Feierabend wrote on Facebook. “Let the feasting begin.”
“Some bats and birds do eat mosquitoes, but Aedes aegypti mosquitoes, which are Zika carriers, typically dwell in or around people’s houses — not an easy hunting ground for predators,” says Meghan Rosen, who also reported on the virus for this special report (SN: 4/2/16, p. 26). The mosquitoes lay eggs in water though, so predatory fish and crustaceans could serve as a type of biological control. But, according to the U.S. Centers for Disease Control and Prevention, that option may not be practical. Ae. aegypti larvae can also develop in dog bowls, plant saucers and rain splash left in crumpled plastic bags, Milius notes. Wandering baby Jupiter As proto-Jupiter moved through the solar system, it may have absorbed so much planet-building material that it reduced the number of planets that could form near the sun, Christopher Crockett reported in “Jupiter could have formed near sun,” (SN: 4/2/16, p. 7).
“Over what time span would this have occurred, and are any of our planets currently moving in or out?” asked online reader Mark S.
If Jupiter formed close to the sun, it spent only about 100,000 years in the inner solar system, well before the rocky planets started to form, Crockett says. “Researchers suspect that the outer planets danced around quite a bit during their formative years. All the sun’s worlds are now, fortunately, staying put for the foreseeable future,” he says.
Addicted to microbes In “Microbes and the mind” (SN: 4/2/16, p. 22), Laura Sanders reported on the surprising ways in which gut microbes influence depression, anxiety and other mental disorders. But it’s not a one-way street. “Our behavior can influence the microbiome right back,” she wrote.
Reader George Szynal wondered how addiction to drugs, alcohol and other substances may influence microbes and vice versa. “Can treatments of microbiome enhance and aid the recovery of addicted persons?” he asked.
“That’s a fascinating idea, but so far, little research has been done on this question,” Sanders says. “Alcohol disorders have been linked to changes in the gut microbiome, and smoking has been linked to differences in mouth bacteria. But until scientists figure out whether those microbe changes are consequences or causes of the addictions, we won’t know whether changing the microbes could help people kick the habits,” she says.
Water rising Without a sharp decrease in carbon dioxide emissions, rapid melting of the Antarctic ice sheet could raise sea levels by 60 meters by the end of the century, Thomas Sumner reported in “Tipping point for ice sheet looms” (SN: 4/2/16, p. 10).
In addition to melting ice sheets, reader Carolyn Lawson asked if human depletion of groundwater also contributes to sea level rise.
About 80 percent of groundwater losses end up in the oceans, according to a recent study in Nature Climate Change. Simulations showed that groundwater contributed about 0.02 millimeters of sea level rise annually in 1900 and increased to around 0.27 millimeters annually by 2000. “Current sea level rise is about 3 millimeters per year, so that’s a pretty large chunk,” Sumner says. “Unfortunately, Earth’s groundwater reserves are disappearing. It’s unclear whether the groundwater contribution to sea level rise will continue to increase indefinitely.”
