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Evidence is piling up that much of the universe’s missing matter is lurking along the strands of a vast cosmic web.

A pair of papers report some of the best signs yet of hot gas in the spaces between galaxy clusters, possibly enough to represent the half of all ordinary matter previously unaccounted for. Previous studies have hinted at this missing matter, but a new search technique is helping to fill in the gaps in the cosmic census where other efforts fell short. The papers were published online at arXiv.org on September 15 and September 29.
Two independent teams stacked images of hundreds of thousands of galaxies on top of one another to reveal diffuse filaments of gas connecting pairs of galaxies across millions of light-years. Measuring how the gas distorted the background light of the universe let the researchers determine the mass of ordinary matter, or baryons, that it held — the protons and neutrons that make up atoms.

“It’s a very important problem,” says Dominique Eckert of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, who has searched for the missing matter via X-rays emitted by individual strands. “If you want to understand how galaxies form and how everything forms within a galaxy, you have to understand the evolution of the baryon content.” That starts with knowing where it is.

About 85 percent of the matter in the universe is mysterious, invisible stuff called dark matter, which physicists have yet to find (SN Online: 9/6/17). Weirdly, about half of the ordinary matter is also unaccounted for. When astronomers look around at the galaxies in the nearest few billion light-years, they find only about half the baryons that should have been produced in the Big Bang.

The rest is probably hiding in long filaments of gas that connect galaxy clusters in a vast cosmic web (SN: 3/8/14, p. 8). Previous attempts to find the baryons focused on X-rays emitted by gas in the filaments (SN Online: 8/4/15) or on the light of distant quasars filtering through these cobwebby strands (SN: 5/13/00, p. 310). But those efforts were either inconclusive, or were sensitive to such a narrow range of gas temperatures that they missed much of the matter.

Now there might be a way to find the rest. Two groups — cosmologist Hideki Tanimura, who did the work while at the University of British Columbia in Vancouver, and his colleagues, and Anna de Graaff of the University of Edinburgh and her colleagues — have sought the missing matter in a new way. Both teams found a way to look through the gas all the way back to the oldest light in the universe.
“Filamentary gas is very difficult to detect, but now we have a technique to detect it,” says Tanimura, now with the Institute of Space Astrophysics in Orsay, France.

That ancient light, called the cosmic microwave background, was emitted 380,000 years after the Big Bang. When this light passes though clouds of electrons in space — such as those found in filaments of hot gas — it gets deflected and distorted in a specific way. The Planck satellite released an all-sky map of these distortions in 2015 (SN: 3/21/15, p. 7).

Tanimura and de Graaff separately figured that there would be more distortion along the filaments than in empty space. To locate the filaments, both teams chose pairs of galaxies from the Sloan Digital Sky Survey catalog that were at least 20 million light-years apart. De Graaff’s team chose roughly a million pairs, and Tanimura’s team chose 262,864 pairs. Both teams assumed that the galaxies were not part of the same cluster, but that they should be connected by a filament.

The filaments were still too faint to see individually, so the teams used software to layer all the images and subtracted out distortion from electrons in the galaxies to see what was left. Both saw a residual distortion in the cosmic microwave background, which they attribute to the filaments.

Next, de Graaff’s team calculated that those filaments account for 30 percent of the total baryon content of the universe. That’s surely an underestimate, since they didn’t examine every filament in the universe, the team writes — the rest of the missing matter is probably there too.

“Both groups here took the obvious first step,” says Michael Shull of the University of Colorado Boulder, who was not involved in the new studies. “I think they’re on the right track.” But he worries that the gas they see might have been ejected from galaxies at high speeds, and so not actually the missing matter at all.

Eckert also worries that the gas may belong more to the galaxies than to their intergalactic tethers. Future observations of the composition of the gas, as well as more sensitive X-ray observations, could help solve that part of the puzzle.

Voices carry so much information. Joy and anger, desires, comfort, vocabulary lessons. As babies learn about their world, the voice of their mother is a particularly powerful tool. One way mothers wield that tool is by speaking in the often ridiculous, occasionally condescending baby talk.

Also called “motherese,” this is a high-pitched, exaggerated language full of short, slow phrases and big vocal swoops. And when confronted with a tiny human, pretty much everybody — not just mothers, fathers and grandparents — instinctively does it.

Now, a study has turned up another way mothers modulate their voice during baby talk. Instead of focusing on changes such as pitch and rhythm, the researchers focused on timbre, the “color” or quality of a sound.

Timbre is a little bit nebulous, kind of a “know it when you hear it” sort of thing. For instance, the timbre of a reedy clarinet differs from a bombastic trumpet, even when both instruments are hitting the same note. The same is true for voices: When you hear the song “Hurt,” you don’t need to check whether it’s Nine Inch Nails’ Trent Reznor or Johnny Cash singing it. The vocal fingerprints make it obvious.
It turns out that timbre isn’t set in stone. People — mothers, in particular — change their timbre, depending on whether they’re talking to their baby or to an adult, scientists report online October 12 in Current Biology.

For the study, 12 English-speaking moms brought their babies into a Princeton lab. Researchers recorded the women talking to or reading to their 7- to 12-month old babies, and talking with an adult.
An algorithm sorted through timbre data taken from both baby- and adult-directed speech, and used this input to make a mathematical classifier. Based on snippets of speech, the classifier then could tell whether a mother was talking with an adult or with her baby. The timbre differences between baby- and adult-directed speech were obvious enough that a computer program could tell them apart.

Similar timbre shifts were obvious in other languages, too, the researchers found. These baby-directed shifts happened in 12 different women who spoke Cantonese, French, German, Hebrew, Hungarian, Polish, Russian, Mandarin or Spanish — a consistency that suggests this aspect of baby talk is universal.

Defined mathematically, these timbre shifts were consistent across women and across languages, but it’s still not clear what vocal qualities drove the change. “It likely combines several features, such as brightness, breathiness, purity or nasality,” says study coauthor Elise Piazza, a cognitive neuroscientist at Princeton University. She and her colleagues plan on studying these attributes to see whether babies pay more attention to some of them.

It’s not yet known whether babies perceive and use the timbre information from their mother. Babies recognize their mother’s voice; it’s possible they recognize their mother’s baby-directed timbre, too. Babies can tell timbre differences between musical instruments, so they can probably detect timbre differences in spoken language, Piazza says.
The work “highlights a new cue that mothers implicitly use,” Piazza says. The purpose of this cue isn’t clear yet, but the researchers suspect that the timbre change may emotionally engage babies and help them learn language.

People may not reserve timbre shifts just for babies, Piazza points out. Politicians talking to voters, middle school teachers talking to a classroom, and lovers whispering to each other may all tweak their timbre to convey … something.

Beer breweries’ trash may have been Danish painters’ treasure.

The base layer of several paintings created in Denmark in the mid-1800s contains remnants of cereal grains and brewer’s yeast, the latter being a common by-product of the beer brewing process, researchers report May 24 in Science Advances. The finding hints that artists may have used the leftovers to prime their canvases.

Records suggest that Danish house painters sometimes created glossy, decorative paint by adding beer, says Cecil Krarup Andersen, a conservator at the Royal Danish Academy in Copenhagen. But yeast and cereal grains have never been found in primer.
Andersen had been studying paintings from the Danish Golden Age, an explosion of artistic creativity in the first half of the 19th century, at the National Gallery of Denmark. Understanding these paintings’ chemical compositions is key to preserving them, she says. As part of this work, she and colleagues looked at 10 pieces by Christoffer Wilhelm Eckersberg, considered the father of Danish painting, and his protégé Christen Schiellerup Købke.

Canvas trimmings from an earlier conservation effort allowed for an in-depth analysis that wouldn’t have otherwise been possible, since the process destroys samples. In seven paintings, Saccharomyces cerevisiae proteins turned up, as well as various combinations of wheat, barley, buckwheat and rye proteins. All these proteins are involved in beer fermentation (SN: 9/19/17).

Tests of an experimental primer that the researchers whipped up using residual yeast from modern beer brewing showed that the mixture held together and provided a stable painting surface — a primary purpose of a primer. And this concoction worked much better than one made with beer.

Beer was the most common drink in 1800s Denmark, and it was akin to liquid gold. Water needed to be treated prior to consuming and the brewing process took care of that. As a result, plenty of residual yeast would have been available for artists to purchase, the researchers say.

If the beer by-product is found in paintings by other artists, Andersen says, that information can help conservators better preserve the works and better understand the artists’ lives and craftsmanship. “It’s another piece of the puzzle.”

While volunteering at the University of New Mexico’s Children’s Hospital in Albuquerque, Quinton Smith quickly realized that he could never be a physician.

Then an undergrad at the university, Smith was too sad seeing sick kids all the time. But, he thought, “maybe I can help them with science.”

Smith had picked his major, chemical engineering, because he saw it as “a cooler way to go premed.” Though he ultimately landed in the lab instead of at the bedside, he has remained passionate about finding ways to cure what ails people.

Today, his lab at the University of California, Irvine uses tools often employed in fabricating tiny electronics to craft miniature, lab-grown organs that mimic their real-life counterparts. “Most of the time, when we study cells, we study them in a petri dish,” Smith says. “But that’s not their native form.” Prodding cells to assemble into these 3-D structures, called organoids, can give researchers a new way to study diseases and test potential treatments.

By combining Silicon Valley tech and stem cell biology, scientists are now “making tissues that look and react and function like human tissues,” Smith says. “And that hasn’t been done before.”

The power of stem cells
Smith’s work began in two dimensions. During his undergraduate studies, he spent two summers in the lab of biomedical engineer Sharon Gerecht, then at Johns Hopkins University. His project aimed to develop a device that could control oxygen and fluid flow inside minuscule chambers on silicon wafers, with the goal of mimicking the environment in which a blood vessel forms. It was there that Smith came to respect human induced pluripotent stem cells.

These stem cells are formed from body cells that are reprogrammed to an early, embryonic stage that can give rise to any cell type. “It just blew my mind that you can take these cells and turn them into anything,” Smith says.

Smith ultimately returned to Gerecht’s lab for his Ph.D., exploring how physical and chemical cues can push these stem cells toward becoming blood vessels. Using a technique called micropatterning — where researchers stamp proteins on glass slides to help cells attach — he spurred cells to organize into the beginnings of artificial blood vessels. Depending on the pattern, the cells formed 2-D stars, circles or triangles, showing how cells come together to form such tubular structures.
While a postdoc at MIT, he transitioned to 3-D, with a focus on liver organoids.

Like branching blood vessels, a network of bile ducts carry bile acid throughout the liver. This fluid helps the body digest and absorb fat. But artificial liver tissue doesn’t always re-create ducts that branch the way they do in the body. Cells growing in the lab “need a little bit of help,” Smith says.
To get around the problems, Smith and his team pour a stiff gel around minuscule acupuncture needles to create channels. After the gel solidifies, the researchers seed stem cells inside and douse the cells in chemical cues to coax them to form ducts. “We can create on-demand bile ducts using an engineering approach,” he says.

This approach to making liver organoids is possible because Smith speaks the language of biology and the language of engineering, says biomedical engineer Sangeeta Bhatia, a Howard Hughes Medical Institute investigator at MIT and Smith’s postdoc mentor. He can call on his cell biology knowledge and leverage engineering techniques to study how specific cell types are organized to work together in the body.

For example, Smith’s lab now uses 3-D printing to ensure liver tissues grown in the lab, including blood vessels and bile ducts, organize in the right way. Such engineering techniques could help researchers study and pinpoint the root causes behind some liver diseases, such as fatty liver disease, Smith says. Comparing organoids grown from cells from healthy people with those grown from cells from patients with liver disease — including Hispanic people, who are disproportionately affected — may point to a mechanism.

Looking beyond the liver
But Smith isn’t restricting himself to the liver. He and his trainees are branching out to explore other tissues and diseases as well.

One of those pursuits is preeclampsia, a disease that affects pregnant women, and disproportionately African American women. Women with preeclampsia develop dangerously high blood pressure because the placenta is inflamed and constricting the mother’s blood vessels. Smith plans to examine lab-grown placentas to determine how environmental factors such as physical forces and chemical cues from the organ impact attached maternal blood vessels.

“We’re really excited about this work,” Smith says. It’s only recently that scientists have tricked stem cells to enter an earlier stage of development that can form placentas. These lab-grown placentas even produce human chorionic gonadotropin, the hormone responsible for positive pregnancy tests.

Yet another win for the power of stem cells.

New gene-editing tools can correct typos that account for about half of disease-causing genetic spelling errors.

Researchers have revamped the CRISPR/Cas9 gene editor so that it converts the DNA base adenine to guanine, biological chemist David Liu and colleagues report October 25 in Nature. In a separate study, published October 25 in Science, other researchers led by CRISPR pioneer Feng Zhang re-engineered a gene editor called CRISPR/Cas13 to correct the same typos in RNA instead of DNA.
Together with other versions of CRISPR/Cas9, the new editors offer scientists an expanded set of precision tools for correcting diseases.

CRISPR/Cas9 is a molecular scissors that snips DNA. Scientists can guide the scissors to the place they want to cut in an organism’s genetic instruction book with a guide RNA that matches DNA at the target site. The tool has been used to make mutations or correct them in animals and in human cells, including human embryos (SN: 10/14/17, p. 8).

A variety of innovations allow CRISPR/Cas9 to change genetic instructions without cutting DNA (SN: 9/3/16, p. 22). Earlier versions of these “base editors,” which target typos related to the other half of disease-causing genetic spelling errors, have already been used to alter genes in plants, fish, mice and even human embryos.
Such noncutting gene editors are possibly safer than traditional DNA-cutting versions, says Gene Yeo, an RNA biologist at the University of California, San Diego. “We know there are drawbacks to cutting DNA,” he said. Mistakes often arise when cellular machinery attempts to repair DNA breaks. And although accurate, CRISPR sometimes cuts DNA at places similar to the target, raising the possibility of introducing new mutations elsewhere. Such “permanent irreversible edits at the wrong place in the DNA could be bad,” Yeo says. “These two papers have different ways to solve that problem.”
The new editors allow researchers to rewrite all four bases that store information in DNA and RNA. Those four bases are adenine (A) which pairs with thymine (T) (or uracil (U) in RNA), and guanine (G) pairs with cytosine (C). Mutations that change C-G base pairs to T-A pairs happen 100 to 500 times every day in human cells. Most of those mutations are probably benign, but some may alter a protein’s structure and function, or interfere with gene activity, leading to disease. About half of the 32,000 mutations associated with human genetic diseases are this type of C-G to T-A change, says Liu, a Howard Hughes Medical Institute investigator at Harvard University. Until now, there was little anyone could do about it, he says.

In RNA, DNA’s chemical cousin, some naturally occurring enzymes can reverse this common mutation. Such enzymes chemically convert adenine to inosine (I), which the cell interprets as G. Such RNA editing happens frequently in octopuses and other cephalopods and sometimes in humans (SN: 4/29/17, p. 6).

Zhang, of the Broad Institute of MIT and Harvard, and colleagues made an RNA-editing enzyme called ADAR2 into a programmable gene-editing tool. The team started with CRISPR/Cas13, molecular scissors that normally cut RNA. Dulling the blades let the tool grasp instead of slice. Zhang and colleagues then bolted the A-to-I converting portion of ADAR2 onto CRISPR/Cas13. Dubbed REPAIR, the conglomerate tool edited from 13 percent to about 27 percent of RNAs of two genes in human cells grown in dishes. The researchers did not detect any undesired changes.

Editing RNA is good for temporary fixes, such as shutting down inflammation-promoting proteins. But to fix many mutations, it requires permanent DNA repairs, says Liu.

In 2016, Liu’s team made a base editor that converts C to T. Chinese researchers reported in Protein & Cell on September 23 that they used the old base editor in human embryos to repair a mutation that causes the blood disorder beta-thalassemia. But that editor couldn’t make the opposite change, switching A to G.

Unlike with RNA, no enzymes naturally make the A-to-I conversion in DNA. So Nicole Gaudelli in Liu’s lab forced E. coli bacteria to evolve one. Then the researchers bolted the E. coli DNA converter, TadA, to a “dead” version of Cas9, disabled so it couldn’t cut both strands of DNA. The result was a base editor, called ABE, that could switch A-T base pairs into G-C pairs in about 50 percent of human cells tested.

This base editor works more like a pencil than scissors, Liu says. In lab dishes, Liu’s team corrected a mutation in human cells from a patient with an iron-storage blood disorder called hereditary hemochromatosis. The team also re-created beneficial mutations that allow blood cells to keep making fetal hemoglobin. Those mutations are known to protect against sickle cell anemia.

Another group reported in the October Protein & Cell that base editing appears to be safer than traditional cut-and-paste CRISPR/Cas9 editing. Liu’s results seem to support that. His team found that about 14 percent of the time cut-and-paste CRISPR/Cas9 made changes at nine of 12 possible “off-target” sites. The new A-to-G base editor altered just four of the 12 off-target sites and only 1.3 percent of the time.

That’s not to say cut-and-paste editing isn’t useful, Liu says. “Sometimes, if your task is to cut something, you’re not going to do that with a pencil. You need scissors.”

For an animal already amazing enough to walk on water, what could growing feather fans on its legs possibly add?

These fans have preoccupied Abderrahman Khila of the University of Lyon in France, who keeps some 30 species of bugs called water striders walking the tanks in his lab without getting their long, elegant legs wet.

“Walk” may be too humdrum a word. The 2,200 or so known species of water striders worldwide can zip, skim, skate and streak. Among such damp-defying acrobats, however, only the Rhagovelia genus grows a fan of delicate feathers on the middle pair of its six legs. Even little hatchlings head-banging their way out of underwater eggs have a pair of feathery microfluffs for their perilous swim up to cruise the water’s surface.
A first guess at a function — maybe plumes help support bigger adults — would be wrong, Khila says. The Rhagovelia are not giants among water striders. In a jar of alcohol in his lab, he treasures a specimen of a much bigger species, with a body about the size of a peanut and a leg span that can straddle a CD. Yet this King Kong among striders, found in Vietnam and China, slides over the water as other species do, cushioned by air trapped in dense hydrophobic leg bristles. No froufrou feathers needed.
Fans aren’t required either for water striders’ action-packed, often violent lives. “In the lab, they eat each other all the time,” Khila says. A newly molted strider, still soft and weak after 10 minutes of wriggling out of its old external skeleton, can get mobbed by cannibals. Any other insect, such as a mosquito, that lands on the water surface also triggers a frenzy. Small striders “start to attack the legs of the mosquito,” he says, “and seconds later there are 50 water striders gathered around.” With their tubelike mouthparts, the striders stab holes in the victim and inject enzymes to liquefy flesh into a meat shake to suck out.

For these Rhagovelia, Khila sees the fans as “one of those examples of ‘key evolutionary innovations,’” traits that just “pop up” in evolutionary history with no clear line of precursors or partial forms, he says. Now he and his colleagues have identified a fan benefit. When they removed plumes from the bugs or suppressed genes for fan formation, the mutant striders couldn’t turn as deftly or run upstream against the current as fully fanned Rhagovelia can, the researchers report in the Oct. 20 Science. Striders in a closely related but fanless genus were likewise hampered. The innovative fan opened up new territory, helping the insects navigate flowing water, the researchers conclude.

Fan-maker genes were intriguing in another way. Evolutionary biologists have long debated whether such evolutionary innovations just repurpose and recombine old developmental genes or actually rely on new ones. In the case of the fans, two genes, which the researchers named geisha and mother-of-geisha after geisha fans, are unique to this genus, but three other genes are repurposed. So in a twist on an old debate, Khila says, “neither hypothesis is wrong.”

It is “extremely likely” that humans are driving warming on Earth since the 1950s. That statement — which indicates a 95 to 100 percent confidence in the finding — came in a report released November 3 by the U.S. Global Change Research Program. This interagency effort was established in 1989 by presidential initiative to help inform national science policy.

The 2017 Climate Science Special Report, which lays out the current state of scientific knowledge on climate change, will be rolled into the fourth National Climate Assessment, set to be released in late 2018.
The last national climate assessment, released in 2014, also concluded that recent warming was mostly due to humans, but didn’t give a confidence level (SN Online: 5/6/14). Things haven’t gotten better. Ice sheet melting has accelerated, the 2017 report finds. As a result, projections of possible average global sea level rise by 2100 under a high greenhouse gas emissions scenario (in which emissions rise unabated throughout the 21st century) have increased from 2 meters to as much as 2.6 meters.

In addition, the report notes that three of the warmest years on record — 2014, 2015 and 2016 — occurred since the last report was released; those years also had record-low sea ice extent in the Arctic Ocean in the summer.

The report also notes some still-unresolved questions that have become increasingly active areas of research. One big one: How will climate change alter atmospheric circulation in the mid-latitude areas? Scientists are wrangling with whether and how these changes will affect storm patterns and contribute to extreme weather events, including blizzards and drought.

Around the six-month mark, babies start to get really fun. They’re not walking or talking, but they are probably babbling, grabbing and gumming, and teaching us about their likes and dislikes. I remember this as the time when my girls’ personalities really started making themselves known, which, really, is one of the best parts of raising a kid. After months of staring at those beautiful, bald heads, you start to get a glimpse of what’s going on inside them.

When it comes to learning language, it turns out that a lot has already happened inside those baby domes by age 6 months. A new study finds that babies this age understand quite a bit about words — in particular, the relationships between nouns.
Work in toddlers, and even adults, reveals that people can struggle with word meanings under difficult circumstances. We might briefly falter with “shoe” when an image of a shoe is shown next to a boot, for instance, but not when the shoe appears next to a hat. But researchers wanted to know how early these sorts of word relationships form.

Psychologists Elika Bergelson of Duke University and Richard Aslin, formerly of the University of Rochester in New York and now at Haskins Laboratories in New Haven, Conn., put 51 6-month-olds to a similar test. Outfitted with eye-tracking gear, the babies sat on a parent’s lap and looked at a video screen that showed pairs of common objects. Sometimes the images were closely related: mouth and nose, for instance, or bottle and spoon. Other pairs were unrelated: blanket and dog, or juice and car.

When both objects were on the screen, the parents would say a sentence using one of the words: “Where is the nose?” for instance. If babies spent more time looking at the nose than the other object, researchers inferred that the babies had a good handle on that word.

When the babies were shown tricky pairs of closely related objects, like a cup of juice and a cup of milk, the babies spent nearly equal time looking at both pictures, no matter what word their parents said. But when the images were really distinct (juice and car, for instance) the babies spent more time looking at the spoken word.
These babies detected a difference between the “milk-juice” pair and the “juice-car” pair, recognizing that one pair is similar and the other isn’t, the researchers conclude November 20 in the Proceedings of the National Academy of Sciences.
To see whether this ability was tied to domestic life, the researchers sent the babies home with specialized gear: vests with audio recorders and adorable hats outfitted with small video cameras, one just above each ear. A camera on a tripod in a corner of the home also captured snippets of daily life. The resulting video and audio recordings revealed that babies whose caregivers used more nouns for objects in the room were better at the word task in the lab.

That means that babies learn words well when they can actually see the object being talked about. Hearing, “Open your mouth. Here comes the spoon!” as they watch the spoon come flying toward their face makes a bigger vocabulary impression than “Did you like riding in the car yesterday?”

A similar idea came from a recent study on preschoolers. These kids learned best when they saw one picture at a time (or when parents pointed at the relevant object). Babies — and older kids, too — like to see what you’re talking about.

The results are too early to provide advice to parents, says Bergelson, a cognitive and developmental psychologist. “But I think one thing suggested by our work is that parents should consider their young baby to be a real conversational partner,” she says. “Even young infants are listening and learning about words and the world around them before they start talking themselves, and their caregivers make that possible.”

There’s still lots to figure out about how babies soak up vocabulary. And as scientists come up with more ways to peer into the mysterious inner workings of a baby’s mind, those answers might lead to even more interesting conversations with our babies.

A new analysis is shedding light on drought in Mongolia, both past and future.

By studying the rings of semifossilized trees, researchers constructed a climate history for the semiarid Asian nation spanning the last 2,060 years — going 1,000 years further back than previous studies.

It was suspected that a harsh drought from about 2000 to 2010 that killed tens of thousands of livestock was unprecedented in the region’s history and primarily the result of human-caused climate change. But the tree ring data show that the dry spell, while rare in its severity, was not outside the realm of natural climate variability, researchers report online March 14 in Science Advances.
“This is a part of the world where we don’t know about the past climate,” says Park Williams, a bioclimatologist at Columbia University’s Lamont-Doherty Earth Observatory in Palisades, N.Y., who was not involved with the study. “Having this record is a great resource for trying to understand past droughts in the region.”

In recent years, many studies have sought to unsnarl the role of anthropogenic climate change from natural variability on extreme weather events (SN: 1/20/18, p. 6). Such work is necessary for more accurately predicting future climate trends and helping governments prepare for the most severe scenarios, says study coauthor Amy Hessl, a physical geographer at West Virginia University in Morgantown. This is especially true in countries like Mongolia that lack certain infrastructure, such as enough water reservoirs, to ease the impact of events like prolonged drought.

Hessl and her colleagues studied tree rings in hundreds of samples of Siberian pines, well-preserved by Mongolia’s naturally dry climate. A ring’s width indicates how much the tree grew in a year. In wet years, the rings are wider; in dry years, skinnier.
The recent dry spell was the severest in recorded history. But the rings showed that an even more severe drought took place around the year 800, long before anthropogenic climate change began.

Still, computer simulations suggest that about a third of the recent drought’s severity could have been caused by elevated temperatures linked to climate change, the researchers found. The finding is consistent with studies on how climate change has affected other recent droughts in South Africa and California.

Using computer simulations, Hessl and her colleagues conclude that droughts in coming decades may not be any worse than those seen in Mongolia’s past. The team predicts that as global temperatures rise over the next century, Mongolia will first become drier, then wetter. Increased heat initially will dry out the plains. But at a certain point, hot air holds more moisture, leading to increased precipitation.

Those climate patterns will likely guide how Mongolia develops, Hessl says, because they have in the past. In 2014, she and colleagues published a paper detailing how a 15-year period of unprecedented temperate and rainy conditions in 13th century Mongolia may have led to the rise of Genghis Khan (SN Online: 3/10/14).

After some initial waffling, President Trump signed a budget bill March 23 that lays out spending details for the rest of fiscal year 2018, which goes through September. The $1.3-trillion spending deal boosts funding for nearly all science agencies, avoiding cuts the White House had proposed.

These increases stem largely from February’s budget deal, which raised caps on discretionary spending. The National Institutes of Health, which got a $3 billion bump over the 2017 level, comes out especially well, as does the Department of Energy’s Office of Science. It receives an $868 million boost, a 16 percent increase. Climate science research and programs across several agencies also avoided big cuts that the administration had proposed.
The one outlier: the Environmental Protection Agency. At about $8.1 billion, its budget remains flat at the 2017 level.

Here are a few details that stood out to us.

NIH
NIH gets an extra $414 million for Alzheimer’s disease research, along with $400 million for the BRAIN Initiative, a research project announced by President Obama in 2013 that aims to improve our understanding of the human brain.
DOE Office of Science
Trump had proposed eliminating the Advanced Research Projects Agency-Energy, which funds research into long-shot but potentially high-reward projects. But the bill allocates an additional $47 million to the agency, a resounding rejection of the administration’s request.

NASA
The Wide-Field Infrared Survey Telescope, or WFIRST, is a proposed mission to study, in part, planets orbiting stars outside the solar system. It was recommended by the most recent decadal survey for astrophysics and remains one of NASA’s top astrophysics priorities after the James Webb Space Telescope. Trump has proposed canceling WFIRST, but the spending package includes $150 million for the telescope. Four earth science programs that Trump had targeted for elimination were also funded.

CDC
The agreement includes wording clarifying that the Centers for Disease Control and Prevention isn’t barred from studying gun violence under a 1996 amendment. The CDC has shied away from such research since that time. On Twitter, some celebrated the news, but others hailed it as a partial victory. Megan Ranney, an emergency physician and researcher at Brown University in Providence, R.I., who studies firearm injuries, tweeted the “announcement changes nothing. The issue has been, and continues to be, lack of appropriations for research.”

EPA
The agency’s overall budget remains flat as do projects with EPA’s Office of Science & Technology. Although not research related, the agency’s regulatory programs are cut by $23.5 million. The bill includes wording that prohibits the regulation of lead content in ammunition and fishing tackle and exempting livestock producers from EPA greenhouse gas regulations.

USGS
The bill includes $23 million for ShakeAlert, an earthquake early warning system on the West Coast that could be rolled out as early as October, another project that had been facing elimination. All eight of the U.S. Geological Survey’s climate science centers are funded in the agreement. The administration had proposed cutting their numbers in half, to four.