The largest particle detector of its kind has failed to turn up any hints of dark matter, despite searching for about a year.
Known as XENON1T, the experiment is designed to detect elusive dark matter particles, which are thought to make up most of the matter in the cosmos. Physicists don’t know what dark matter is. One of the most popular explanations is a particle called a WIMP, short for weakly interacting massive particle. XENON1T searches for WIMPs crashing into atomic nuclei in 1,300 kilograms of chilled liquid xenon. But XENON1T saw no such collisions. The particles’ absence further winnowed down their possible hiding places by placing new limits on how frequently WIMPs can interact with nuclei depending on their mass.
Researchers describe the results May 28 in two talks, one at Gran Sasso National Laboratory in Italy, where XENON1T is located, and the other at the European particle physics lab CERN in Geneva. XENON1T had previously reported no hint of WIMPs using about a month’s worth of data (SN: 9/30/17, p. 17). The new study, however, was highly anticipated by physicists, as the longer search provided a better chance for spotting WIMPs.
As the WIMP window narrows, scientists are preparing to rev up the search, creating larger, more sensitive WIMP detectors, and moving on to search for other possible dark matter particles, such as axions (SN Online: 4/9/18).
The first estimate of how many deaths and heart problems could be avoided under new blood pressure guidelines shows it’s well worth it for the U.S. population to get its blood pressure under control, researchers say.
The new guidelines, announced in 2017 by the American College of Cardiology and the American Heart Association, redefined hypertension as a blood pressure reading of 130/80 or higher (SN: 12/9/17, p.13). The previous threshold was 140/90. As a result, 105 million U.S. adults age 20 and older are now considered to have hypertension, 31 million more than before. An estimated 334,000 deaths could be prevented annually if those aged 40 and older keep their blood pressure below the new threshold, researchers report online May 23 in JAMA Cardiology. And 610,000 heart attacks, strokes and other consequences of cardiovascular disease could also be avoided each year. The shift to the lower blood pressure target prevents an additional 156,000 deaths and 340,000 cardiovascular-related illnesses compared with the previous target.
But adhering to the guidelines means doctors may recommend that 83 million adults, 11 million more than before, take blood pressure medications. Those drugs carry a risk of side effects, including kidney damage or abnormally low blood pressure. Of those taking the drugs, 62,000 people’s blood pressure could dip too low and 79,000 might suffer kidney injury or failure, epidemiologist Jiang He of Tulane University in New Orleans and his colleagues estimate.
More research is needed on whether kidney damage related to blood pressure drugs is long-term or temporary, He says. But taking the medication is far less expensive than dealing with a possible heart attack or stroke, he adds.
“Our data really show the beneficial effect of lower blood pressure,” He says.
Some dogs in China carry a mixed bag of influenza viruses. The discovery raises the possibility that dogs may be able to pass the flu to people, perhaps setting off a pandemic.
About 15 percent of pet dogs that went to the vet because of respiratory infections carried flu viruses often found in pigs, researchers report June 5 in mBio. Of the virus strains detected, three have recombined in dogs to form new varieties.
That mixing generates genetic diversity in the viruses that makes them potentially a pandemic threat, says study coauthor Adolfo García-Sastre, a virologist who directs the Global Health and Emerging Pathogens Institute of the Icahn School of Medicine at Mount Sinai in New York City. Evolution of the flu viruses in dogs has been very rapid, occurring in just a few years, García-Sastre says. There’s no sign yet that the dog flu viruses can infect people, but that could change. “The more diversity of viruses there is in an animal reservoir, the higher the chances that it will lead to a version of the virus that is able to jump” to humans, he says.
Pigs and birds remain the prime suspects for mixing up the next human pandemic influenza virus, says Amesh Adalja, an infectious disease physician at Johns Hopkins University and a spokesperson for the Infectious Diseases Society of America. Even if a dog flu virus infected a person, the pathogen may not be able to transmit easily from person-to-person — an important characteristic a virus must have before it can circulate around the world.
But because most people encounter dog noses far more frequently than those of pigs, it’s worth keeping an eye on the pups, Adalja says. “Knowing that dogs could contribute is important for preparing for the next pandemic, because we don’t know exactly what that virus will be,” he says. The first flu virus in dogs was discovered in 2005 in the United States. That pathogen, from a horse flu virus called H3N8 that had jumped to canines, sometimes spreads among pooches in shelters (SN: 10/8/05, p. 237). And, in 2010, some dogs in Asia were found carrying a version of the H3N2 virus from birds. (Cats can catch the dog H3N2 flu virus, but don’t transmit it to other cats, as far as scientists know.)
In the new study, the team swabbed the noses of 800 dogs in the Guangxi region of southern China from 2013 to 2015. All of the dogs had respiratory illnesses, but only 116 were infected with influenza viruses. To the scientists’ surprise, the dogs had various swine H1N1 flu viruses. The researchers determined the genetic makeup of 16 of the samples and discovered that some of these swine viruses had previously circulated in people and pigs in Europe and Asia. Some are strains of bird flu that have infected pigs.
In pigs, the viruses swapped genes among themselves, creating new varieties, some of which were passed to dogs. A virus genetically similar to one of the swine viruses passed to dogs was found in a person in China, raising the possibility that some swine flus can strike both pups and people. Dogs remixed some of the viruses from the pigs with bits of the dog flu virus in Asia, creating the three new canine influenza virus strains, the researchers found.
Since the study collected samples from only one part of China, the team doesn’t know how widespread flu is among dogs, or how many canine-infecting influenzas may be out there.
Finding flu viruses in dogs isn’t cause for alarm. But researchers should monitor the situation and use vaccines, quarantine and other infection-control methods to limit outbreaks and keep the canine viruses from catching hold in humans, García-Sastre says.
From beef to beer, coffee to chocolate, there are environmental costs in what humanity chooses to eat and drink. Now a new study that quantifies the impact on the planet of producing and selling 40 different foods shows how these choices make a difference.
Agricultural data from 38,700 farms plus details of processing and retailing in 119 countries show wide differences in environmental impacts — from greenhouse gas emissions to water used — even between producers of the same product, says environmental scientist Joseph Poore of the University of Oxford. The amount of climate-warming gases released in the making of a pint of beer, for example, can more than double under high-impact production scenarios. For dairy and beef cattle combined, high-impact providers released about 12 times as many greenhouse gases as low-impact producers, Poore and colleague Thomas Nemecek report in the June 1 Science. Those disparities mean that there is room for high-impact producers to tread more lightly, Poore says. If consumers could track such differences, he argues, purchasing power could push for change.
The greatest changes in the effect of a person’s diet on the planet, however, would still come from choosing certain kinds of food over others. On average, producing 100 grams of protein from beef leads to the release of 50 kilograms of greenhouse gas emissions, which the researchers calculated as a carbon-dioxide equivalent. By comparison, 100 grams of protein from cheese releases 11 kilograms in production, from poultry 5.7 kilograms and from tofu two kilograms. Replacing meat and dairy foods from producers with above-average environmental effects with plant-based products could make a notable difference in greenhouse gas emissions. If cuts came from these higher-impact suppliers, replacing half of each kind of animal product with something from a plant could reduce food’s share of emissions by 35 percent. That’s not too far from the 49 percent drop that could be achieved if the whole world, somehow, went vegan. The case for switching to a plant-based diet was already pretty powerful, says Ron Milo of the Weizmann Institute of Science in Rehovot, Israel, who studies cell metabolism and environmental sustainability. The new data “make it even stronger, which is an important thing given how strongly we tend to adhere to our food choices,” he says. In their study, Poore and Nemecek, of the Swiss government research organization Agroscope in Zurich, also considered the amounts of water and land used as well as nutrient runoff and air pollution created from food production. For such an unusually broad analysis, the researchers crunched the numbers from 570 studies of what are called life-cycle assessments for 40 kinds of food. These studies calculated the environmental impacts of the whole process from growing or processing to transporting and retailing each food.
Producing food overall accounts for 26 percent of global climate-warming emissions, and takes up about 43 percent of the land that’s not desert or covered in ice, the researchers found. Out of the total carbon footprint from food, 57 percent comes from field agriculture, livestock and farmed fish. Clearing land for agriculture accounts for 24 percent and transporting food accounts for another 6 percent.
After the first year of putting the study together, Poore himself gave up eating animal products.
Smashing together a billion protons a second wasn’t enough for the Large Hadron Collider.
The particle accelerator, located at CERN in Geneva, is getting spiffed up to allow it to carry out collisions at an even faster rate. On June 15, scientists announced the start of construction for an LHC upgrade called the High-Luminosity LHC.
The upgrade will boost the collision rate by at least a factor of five. That increase should beef up the LHC’s ability to search for new particles and to study the Higgs boson, the particle that the LHC detected in 2012.
The first stage of construction involves establishing new buildings, shafts and caverns to house equipment. Eventually, scientists will begin replacing equipment inside the accelerator, including the magnets that focus and steer the beams of particles. The plan is for the HL-LHC to be in business by 2026.
The last 13 years have been terrible for ancient African baobab trees.
Nine of the 13 oldest either lost trunks or died altogether after having lived for longer than a millennium, researchers report June 11 in Nature Plants. But just what the demise means for the iconic species is up for debate.
“Whilst we are saddened about the death and collapse [of the old trees], current evidence does not indicate that this is affecting the whole population,” says plant scientist Sarah Venter, who was not part of the new study. Venter, with the University of the Witwatersrand in Johannesburg, does not see an immediate threat to the species as a whole. These trees of extreme age “were probably more vulnerable to dry conditions,” she says. “Tree mortality is complex and can be attributed to many causes, including climate change and droughts.” The Adansonia digitata species of the baobab group is the longest-living kind of flowering tree. With its mass of skinny branches dividing like rootlets over a fat trunk, the species sometimes gets teased as an upside-down tree. Long-stemmed brown fruits also encourage the nickname “dead-rat tree.” Yet people have long cherished the giant baobabs for food, medicine and spiritual value.
Of the 13 oldest known A. digitata, four have died since 2005, says study coauthor Adrian Patrut, who specializes in inorganic and nuclear chemistry at Babeş-Bolyai University in Cluj-Napoca, Romania. Five others of these ancient trees across the African continent have lost enormous chunks of their multiple trunks, Patrut and his colleagues report. The oldest to die, the Panke tree in Zimbabwe, had lived about 2,500 years before it collapsed over the course of 2010 and 2011. The other three trees that died, including the Chapman tree in Botswana, were just 1,250 to 1,500 years old. Patrut does not think mere old age caused their demise. He worries something more troubling may be going on instead. “There were no signs of an epidemic,” Patrut says. He suspects that a warming trend observed in southern Africa may be playing a role.
As world-famous as baobabs are, much of their drought biology and other basic matters remain mysterious. “Does anyone really know the rooting structure of baobabs?” laments plant ecologist Eugene Moll of the University of the Western Cape in Bellville, South Africa. For understanding Africa’s plants, “philosophies and paradigms that originate north of 40° N do not necessarily apply down here in the Southern Hemisphere,” he says. “We humans like symmetry but nature is certainly not always symmetrical.”
A zippy little particle has been traced back to its cosmic stomping grounds, a flaring galaxy 4 billion light-years away, for the first time solving a cosmic whodunit.
Scientists have long puzzled over the sources of high-energy particles from space, which batter the Earth at energies that can outstrip the world’s most advanced particle accelerators. Now, physicists have identified the source of an energetic, lightweight particle called a neutrino. The intergalactic voyager came from a type of bright galaxy called a blazar located in the direction of the constellation Orion, scientists report online July 12 in Science. “This is super exciting news,” says astrophysicist Angela Olinto of the University of Chicago, who was not involved with the new result. “It’s marking the beginning of what we call neutrino astronomy,” which uses the nearly massless particles to reveal secrets of cosmic oddities like blazars. While there may be additional cosmic sources for high-energy neutrinos, the detection indicates that at least some come from blazars.
The result also suggests that blazars emit other energetic particles known as cosmic rays, which are produced in tandem with neutrinos. The origins of high-energy cosmic rays are poorly understood and until now, “nobody has ever been able to pinpoint a source that produces them,” says astrophysicist Francis Halzen of the University of Wisconsin–Madison, a leader of IceCube, the Antarctic neutrino observatory that detected the particle.
Thanks to this discovery, “we will better understand nature of the universe’s immense cosmic accelerators,” France Córdova said in a July 12 news conference in Alexandria, Va. Scientists can’t produce such high-energy particles on Earth, “so we have to turn to the heavens to deepen our understanding of the highest-energy processes,” said Córdova, the director of the National Science Foundation, which funded IceCube. IceCube, which was constructed within a cubic kilometer of ice sheet, uses thousands of embedded sensors to measure light produced when neutrinos slam into the ice. On September 22, 2017, IceCube detected a neutrino with an energy of nearly 300 trillion electron volts. (For comparison, protons in the Large Hadron Collider in Geneva reach energies of 6.5 trillion electron volts.) By tracing the neutrino’s track backward, scientists zeroed in on a region of sky in the direction of the constellation Orion. Astronomers leapt into action, and telescopes around the world scoured the spot for light that could reveal the particle’s source. A flare of gamma rays, a type of high-energy light, was detected by the Fermi Gamma-ray Space Telescope coming from a blazar called TXS 0506+056, a brilliant galaxy powered by an enormous black hole that launches a jet of energetic particles in the direction of Earth. A variety of telescopes observed the blazar’s flare in other types of light, including X-rays and radio waves. Coming on the heels of the detection of gravitational waves and light from colliding neutron stars (SN: 11/11/17, p. 6) observed in August 2017, Fermi researcher Regina Caputo thought, “This is crazy, the sky is erupting,” she says. “I almost couldn’t believe it; the universe is revealing itself in ways we have never imagined before,” says Caputo, of NASA’s Goddard Space Flight Center in Greenbelt, Md.
The detection of high-energy neutrinos with a well-defined incoming direction is rare — IceCube sent astronomers only 10 reports of such detections in the year and a half before this neutrino was found. This was the first time researchers were lucky enough to also spot the source’s light.
“This is really what IceCube was built for, to try to see high-energy neutrinos from these exotic sources,” says neutrino physicist Kate Scholberg of Duke University, who was not involved with the research.
Previously, scientists have identified the birthplaces of neutrinos of much lower energies: an exploding star (SN: 2/18/17, p. 24) and the sun. But high-energy neutrinos have been more elusive. While there have been previous hints of high-energy neutrinos associated with blazar flare-ups (SN Online: 4/7/16), the new detection makes the first solid connection between blazars and high-energy neutrinos.
After unmasking the neutrino’s source, the IceCube researchers went back to their data and looked for additional neutrinos that could have come from the blazar. “There was something interesting happening there,” says IceCube researcher Naoko Kurahashi Neilson of Drexel University in Philadelphia. Over seven months starting in September 2014, IceCube saw a neutrino flare, an excess of high-energy neutrinos from that vicinity, the researchers report in a second paper published in the July 13 Science. Blazars are still poorly understood, including what kinds of particles they blast out. Because high-energy neutrinos can be produced only in combination with protons, the detection reveals that blazars are also a source of cosmic rays, which consist of protons and atomic nuclei. Cosmic rays have been detected on Earth at ultrahigh energies, and it’s been a mystery what kind of cosmic engine could rev particles up to those extremes. “This may be a clue to their origin,” says astrophysicist Floyd Stecker of NASA Goddard. But it’s still not clear whether blazars can accelerate protons to the very highest energies observed, he says.
The highest energy cosmic rays are known to come from outside the Milky Way (SN: 10/14/17, p. 7). But in general, cosmic rays leave few clues of their birthplaces: As they travel through space, their trajectories get twisted by magnetic fields, and therefore don’t reliably point back to their sources.
Neutrinos, on the other hand, are electrically neutral, which means they are unaffected by magnetic fields, traveling in a straight line from their origins to Earth. Since high-energy cosmic rays and neutrinos are produced together, the particles can help scientists understand cosmic rays as well, Olinto says. “What neutrinos gave us is a way through the fog.”
Around 5,300 years ago, the Iceman dined on wild meat and grains before meeting his end in the Italian Alps. His last meal was high in fat and optimal for a high-altitude trek, researchers report July 12 in Current Biology.
Since his mummified remains were discovered in 1991, Ötzi’s life has undergone more scrutiny than many reality TV stars. His cause of death, his fashion, his tattoos, his ax, his cholesterol and his genetic instruction book, or genome, have all made headlines (SN 3/24/12, p.5). And in 2002, DNA analysis of samples from the Iceman’s lower intestine suggested that Ötzi ate red deer, goat and grains before he died. In 2011, radiological scans revealed that the mummy’s stomach contents were still intact (SN 9/24/11, p. 8). Now researchers are back with a more in-depth look inside the mummy’s gastrointestinal tract. Based on ancient DNA, proteins and other molecular data, the new analysis confirms the Iceman’s final menu: mountain goat ( Capra ibex), red deer ( Cervus elaphus ), einkorn wheat ( Triticum monococcum ) and other domesticated grains. Traces of a toxic fern ( Pteridium aquilinum ) also turned up — possibly a home remedy for an upset stomach, but more likely either as part of the meal or as a wrapping for the food. While the meal included protein, carbohydrates and fatty acids, fat makes up roughly 46 percent of the stomach contents. And most of that fat came from the goat meat. Test kitchen experiments suggest that the meat was either consumed fresh or slow-dried with smoke.
This high-fat diet probably wasn’t great for Ötzi’s genetic predisposition for heart disease, but it was ideal for the harsh mountain environment. “Even though it might not be tasty, up there you have to provide your body with energy, and fat is a really good energy source,” says study coauthor Frank Maixner of Eurac Research’s Institute for Mummy Studies in Bolzano, Italy. The meal could also be a sign of the times, Maixner says: Ötzi’s people were settled farmers, but when faced with colder temperatures, they may have had to fall back on hunter-gatherer ways. It’s just one meal, cautions Katie Manning of King’s College London who was not affiliated with the study. But “if you look at the palaeodietary evidence from Neolithic Europe, it is clear that wild resources continued to play an important role alongside domesticates, so hunting would have been a persistent activity, probably by specialized hunters.”
Now that researchers have a complete snapshot of the Iceman’s last meal, a census of Ötzi’s gut microbiome — the assortment of tiny organisms that made their home in the mummy’s stomach and intestines — could be next. Helicobacter pylori, a common stomach bug, has already been detected in the Iceman’s gut, and with it came hints of other inhabitants (SN: 2/6/16, p. 14). But Maixner wants to dig beyond “this tip of the iceberg.”
Robert Edwards and Richard Gardner of Cambridge University … say they have been able to remove rabbit embryos … then reimplant only the blastocysts destined to develop into the chosen sex. The implications are obvious and enormous. If this procedure could be extended easily to man there might, for instance, be imbalances, even fads, in the selection by parents of one sex of child over another. — Science News, August 3, 1968.
Update Edwards helped pioneer in vitro fertilization, resulting in the first IVF baby in 1978 and a Nobel Prize in physiology or medicine in 2010. He also foresaw technology’s potential for sex selection. With no sex selection, about 105 males are born for every 100 females worldwide. But in places where sex selection has been encouraged, through IVF and other methods, changes have resulted. In 1995, China’s ratio was 115 boys per 100 girls, according to U.N. estimates. By 2015, men outnumbered women in China by more than 42 million. In 2017, China ended its one-child policy.
Curl the fingers of your left hand over your palm and stick out your thumb like a hitchhiker. Now, you have a rough map of Antarctica — with the inside of your thumb playing the part of the Larsen C ice shelf, says glaciologist Ted Scambos of the National Snow and Ice Data Center in Boulder, Colo.
About a year ago, a massive iceberg roughly the size of Delaware broke off from that ice shelf, and it hasn’t moved much since (SN: 8/5/17, p. 6). The chunk of ice traveled just about 45 kilometers northeast before getting stuck behind an elevated ice promontory called the Bawden ice rise. Researchers monitoring satellite images of the iceberg say it’s been battering Bawden as winds and ocean currents push against the calved ice. That could be a problem, says Anna Hogg, an earth observation researcher at the University of Leeds in England. The Bawden ice rise acts “almost like scaffolding,” providing structure and stability to Larsen C, Hogg says. If it were destabilized, that could potentially lead to the collapse of the rest of the shelf, which could have implications for sea level rise.
That hasn’t happened yet. The iceberg may still be able to escape if it can twist around the tip of Bawden. “Currents and winds carry most of the icebergs in the same direction” — toward South Georgia Island, where many Antarctic icebergs eventually thin out and melt away, Scambos says.
Scientists are eager to study the seabed that was exposed when the iceberg first broke away. That environment could contain microbes and other tiny critters that have been inaccessible until now (SN Online: 10/13/17). An expedition by biologists to the area ended prematurely in February when thick ice prevented the ship from reaching the area (SN Online: 3/3/18). Another effort, aboard a South African icebreaker vessel, is planned for January 2019, Scambos says.
