SAN DIEGO — On some planets that orbit whirling stars, spring and autumn might be the best time to hit the beach, whereas summer offers a midyear respite from sweltering heat. These worlds’ orbits can take them over regions of their sun that radiate wildly different amounts of heat.
“Seasons on a planet like this must be really strange,” says Jonathon Ahlers, a graduate student at the University of Idaho in Moscow, who presented his findings June 15 at a meeting of the American Astronomical Society. Some stars spin so fast that they bulge in the middle. That bulge pushes the equator away from the blazing core, making it much cooler than the poles. A fraction of these stars also host planets that travel on cockeyed orbits, which take these worlds alternately over the poles and equator of their sun.
Ahlers developed computer simulations to see how the differences in solar energy combined with the tilted orbits might affect a planet’s seasons. The outcome depends on how the planet’s axis is tipped relative to its orbit. For a world whose north and south poles periodically face the star’s equator, “you get a cooler summer than normal and an extremely cold winter, but spring and autumn can be hotter than summer,” says Ahlers. “You get two distinct hottest times of the year.”
How that plays out depends on how the planet is built: an atmosphere or oceans could mitigate climate extremes. Ahlers has yet to work out those details. “It’s doing a lot,” he says, “but what, I don’t really know yet.”
Plastic cling wrap with nano-sized pores could give “cool clothes” a new meaning.
The material lets heat escape, instead of trapping it like traditional fabrics, Stanford University materials scientist Yi Cui and colleagues report in the Sept. 2 Science. It could help people keep cool in hot weather, Cui says, and even save energy by reducing the use of air conditioning.
“It’s a very bold new idea,” says MIT physicist Svetlana Boriskina, who wrote an accompanying commentary. Demand for the new material could be far-reaching, she says. “Every person who wears clothes could be a potential user of this product.” Current cooling devices include wearable fans and wicking fabrics; both rely on evaporation to cool human skin. But skin also sheds heat in another way — as infrared radiation. Clothing holds this heat close to the body, Cui says. If infrared radiation could instead pass through fabric, he reasoned, people would feel a lot cooler.
But the fabric would have to be transparent only to infrared wavelengths. To visible light, it would need to be opaque. Otherwise, the clothing would be see-through.
Cui found just one material that satisfied both requirements: a commercially available plastic used in lithium-ion batteries. The material, called nanoporous polyethylene, or nanoPE, is a cling wrap‒like plastic that lets infrared radiation through. But unlike cling wrap, the material isn’t clear: It blocks visible light.
Tiny pores speckled throughout the fabric act as obstacles to visible light, Boriskina says. When blue light, for example, hits the pores, it scatters. So do other colors. The light “bounces around in different directions and scrambles together,” she says. To human eyes, the resulting color is white.
The pores scatter visible light because they’re both in the same size range: The diameters of the pores span 50 to 1,000 nanometers, and the wavelengths of visible light range from 400 to 700 nanometers. Infrared light emitted by the body has a much larger wavelength, 7,000 to 14,000 nanometers, so the plastic’s tiny pores can’t block it. To infrared light, the pores are barely bumps in the road, not barriers. The pores are kind of like small rocks at a beach, Boriskina says. They’ll interfere with the motion of small waves, but big waves will wash right over.
Cui and colleagues tested nanoPE by laying it on a hot plate warmed up to human skin temperature — 33.5° Celsius. NanoPE raised the “skin” temperature by just 0.8 degrees(to 34.3° C). “But when you put on cotton, my God, it rose to 37,” Cui says. “It’s hot!”
The researchers also tried to make nanoPE more wearable than plastic wrap. They coated it with a water-wicking chemical, punched holes in it to make it breathable, and layered it with cotton mesh. Now, the team is working on weaving the fabric to make it feel more like traditional textiles.
“Within five years, I hope someone will start wearing it,” Cui says. “And within 10 years, I hope most people will be wearing it.”
Researchers have digitally unwrapped and read an ancient Hebrew scroll that’s so charred it can’t be touched without falling apart. It turns out the document contains the oldest known Biblical text outside of the roughly 2,000-year-old Dead Sea Scrolls, the investigators say.
Archaeologists discovered the scroll’s remnants in a synagogue’s holy ark during a 1970 excavation in Israel of En-Gedi, a Jewish community destroyed by fire around 600.
In a series of digital steps, slices from a 3-D scan of the En-Gedi scroll were analyzed to bring letters and words into relief on a pieced-together, virtual page. Those images revealed passages from the book of Leviticus written in ink on the scroll’s disintegrating sheets. Radiocarbon results date the scroll to approximately 300, making it the earliest copy of an Old Testament book ever found in a holy ark, scientists report September 21 in Science Advances.
This computerized recovery and conservation process can now be used to retrieve other ancient documents “from the brink of oblivion,” the researchers say.
DENVER — A period of skyrocketing global temperatures started with a bang, new research suggests.
Impact debris and evidence of widespread wildfires around eastern North America suggest that a large space rock whacked Earth around 56 million years ago at the beginning of the Paleocene-Eocene Thermal Maximum, also known as the PETM, a period of rapid warming and huge increases in carbon dioxide. The event is one of the closest historic analogs to modern global warming and is used to improve predictions of how Earth’s climate and ecosystems will fare in the coming decades. Too little is known about the newfound impact to guess its origin, size or effect on the global climate, said geochemist Morgan Schaller of Rensselaer Polytechnic Institute in Troy, N.Y. But it fits in with the long-standing and controversial proposal that a comet impact caused the PETM. “The timing is nothing short of remarkable,” said Schaller, who presented the discovery September 27 at the Geological Society of America’s annual meeting.
The impact may have contributed to the rapid rise in CO2 by stirring carbon up into the atmosphere, but it was hardly the sole cause, said Sandra Kirtland Turner, a geochemist at the University of California, Riverside. Her own environmental simulations suggest that the influx of carbon that flooded Earth during the PETM probably took place over at least 2,500 years, far too drawn out to be caused by a single event, she said at the same meeting.
During the PETM, a massive influx of carbon flooded the atmosphere (SN: 5/30/15, p. 15) and Earth warmed by 5 to 8 degrees Celsius to temperatures much hotter than today. That carbon dump altered the relative abundance of different carbon isotopes in the atmosphere and oceans, leaving a signal in the sedimentary record.
While searching for that signal in roughly 56-million-year-old sediments from sites up and down the U.S. East Coast, Schaller spotted microscopic glassy spheres about the size of a dust mite. These specks resemble those blasted from previously identified large impact events. After switching from a black to a white sorting tray to more easily see the black debris, one of Schaller’s Rensselaer colleagues, micropaleontologist Megan Fung, discovered abundant charcoal pieces in the mix. That charcoal formed when wildfires sparked by the impact raged across the landscape, she proposed.
More evidence of the impact will help researchers to better constrain its location, scope and possible relationship to the start of the PETM, Schaller said.
Two more teeny moons might be lurking around Uranus. That’s in addition to the 27 we already know about. Fluctuations in the density of two of the planet’s dark rings, seen in radio data from the 1986 flyby of the Voyager 2 spacecraft, could be caused by unseen moonlets, Robert Chancia and Matthew Hedman, astronomers at the University of Idaho in Moscow, report online October 9 at arXiv.org.
At probably just 4 to 14 kilometers wide, both moons would be very difficult to detect in Voyager 2 images, the researchers report. New observations with ground-based telescopes might have better luck.
Traffic jams in the brain’s blood supply may play a role in Alzheimer’s disease. A new online game turns people at home into amateur traffic cops. This policing, which involves spotting hard-to-see sluggishness in tiny capillaries in mice, may ultimately help scientists better understand, and perhaps even treat, Alzheimer’s, a devastating disorder that affects over 5 million Americans.
The science behind the game, called Stall Catchers, comes from Cornell University. Chris Schaffer, Nozomi Nishimura and colleagues found that mice designed to exhibit symptoms similar to Alzheimer’s have more blocked blood vessels in their brains than regular mice. That difference can deprive the brain of sustenance and may be a key to understanding how Alzheimer’s damages the brain, the researchers suspect. But finding congested capillaries is a slog. Computers haven’t been up to snuff, and experts could spend an entire year analyzing the thousands of microscope images needed to amass enough data to explore links between Alzheimer’s and blocked vessels. “I thought, if we could change that, it would be tremendous,” says Pietro Michelucci, director of the Human Computation Institute in Fairfax, Va. The institute is a nonprofit organization that runs the EyesOnALZ program, which aims to crowdsource Alzheimer’s research.
That’s where StallCatchers.com comes in. The website asks players to sift through short black-and-white videos of real mouse brains, on the prowl for blocked blood vessels. In the videos, moving blood appears white. But stationary black segments that appear between two white segments signal trouble — a stall. Players rack up points and ascend levels as they classify vessels. With practice, the task gets easier. And people who suffer from performance anxiety shouldn’t fret; each video will be scrutinized by multiple users to get the final verdict. With a little help from the crowd, “not only do [researchers] get answers faster, but they can ask more questions,” Michelucci says.
So far, nearly 1,000 users have played Stall Catchers, Michelucci says. Those players are beginning to generate data that will let researchers see how good these amateur traffic cops are. With luck, their eyes will help unstall the fight against Alzheimer’s.
A “three-parent baby” was born in April, the world’s first reported birth from a controversial technique designed to prevent mitochondrial diseases from passing from mother to child.
“As far as we can tell, the baby is normal and free of disease,” says Andrew R. La Barbera, chief scientific officer of the American Society for Reproductive Medicine. “This demonstrates that, in point of fact, the procedure works.”
The baby boy carries DNA not only from his mother and father but also from an egg donor, raising both safety and ethical concerns. In particular, people worry that alterations of the genetic makeup of future generations won’t stop with preventing diseases but could lead to genetically enhanced “designer babies.” Opponents, such as Marcy Darnovsky, executive director of the Center for Genetics and Society in Berkeley, Calif., are also worried that the technique hasn’t been fully tested. “We wish the baby and family well, and hope the baby stays healthy,” Darnovsky says. “But I have a lot of concerns about this child and about future efforts to use these techniques before they’ve been shown to be safe.”
About one in 4,000 children are born with dysfunctional mitochondria. These energy-generating organelles are inherited from the mother and have their own DNA. Mutations in some of the 37 mitochondrial genes can lead to fatal diseases, often affecting energy-hungry organs such as the brain and muscles. Because there is no cure or effective treatment for many mitochondrial diseases, the recent birth has been heralded as a sign of new hope for affected families.
Even if women don’t have mitochondrial diseases themselves, they can pass the diseases to their children if their egg cells contain large numbers of defective mitochondria. The mother of the recent three-parent baby had previously had two children who died of Leigh syndrome, a mitochondrial disease that affects the nervous system and eventually prevents a person from breathing.
Fertility doctor John Zhang of the New Hope Fertility Center in New York City and colleagues performed what’s called a spindle transfer to put all the chromosomes from the mother’s egg into a donor egg that contained healthy mitochondria but had been emptied of its chromosomes (SN Online: 10/18/16). The egg was then fertilized with sperm and implanted in the mother.
Cell swap A baby boy born in April has DNA from three people. To produce the embryo, researchers transferred the chromosomes from the mother’s egg into a donor egg with healthy mitochondria. The technique is called “spindle transfer” for the cellular structure that segregates the chromosomes.
“It’s very important that they follow up,” to monitor the child’s long-term health, says Shoukhrat Mitalipov, a mitochondrial biologist at Oregon Health & Science University in Portland. Mitalipov pioneered the spindle transfer technique in monkeys (SN: 9/26/09, p. 8). Even a small number of defective mitochondria carried over from the mother’s egg may replicate and cause problems later on, he and other scientists have found (SN: 6/25/16, p. 8; SN Online: 11/30/16).
Zhang reported that just 1.6 percent of the baby boy’s mitochondrial DNA came from his mother (SN Online: 10/19/16). Mitalipov notes, however, that doctors can’t know from sampling a few types of tissue whether other tissues have different levels of mitochondrial carryover. What’s more, levels of mutant mitochondria may change as the child grows.
Mitalipov supports research on the technique but says it should be done in carefully controlled clinical trials. Results of a mouse study published in July suggest that mismatches between the parents’ nuclear DNA and the donor mitochondrial DNA could affect metabolism and aging (SN: 8/6/16, p. 8). Those effects could show up years or decades after birth.
The baby boy born in April is technically not the first three-parent baby. At least two children born in the late 1990s carry mitochondrial DNA from a donor. Those two and 15 other children were born to mothers who had a small amount of cytoplasm — the gelatinous fluid that fills cells and holds mitochondria — from a donor egg injected into their own eggs in an effort to improve results of in vitro fertilization. No major health problems have been reported, but the studies were abandoned because of ethical concerns, lack of funding and the difficulties in obtaining newly required permits.
La Barbera disputes the term “three-parent baby” entirely. “A person’s essence as a human being comes from their nuclear genetic material, not their mitochondrial genetic material,” La Barbera says. Children who are born after mitochondrial transfer procedures have only two parents, he contends.
Zhang drew fire for going to Mexico to perform the procedure. Congress currently bars the U.S. Food and Drug Administration from reviewing applications to make heritable changes in human embryos, which includes the spindle transfer technique. A panel of experts said in February that it is ethical to make three-parent baby boys (SN Online: 2/3/16), a provision that would prevent future generations from inheriting the donor mitochondria. Because mothers pass mitochondria on to their babies but fathers usually do not, technically baby boys born through this technique don’t carry an inheritable modification in their DNA.
Clinics in the United Kingdom can legally perform the procedures, but none have been reported yet. A panel of experts there recommended November 30 that clinical studies could move ahead, so more babies may be born in 2017.
Dinosaurs might live on today as birds, but they hatched like reptiles. Developing dinos stayed in their eggs three to six months before emerging, far longer than previously suspected, researchers report online January 3 in the Proceedings of the National Academy of Sciences.
With few clues to dinosaurs’ embryonic lives, scientists assumed that young dinosaurs shared modern birds’ swift incubation period, which ranges from 45 to 80 days for eggs in the size range of dino eggs. A reptile egg generally takes about twice as long to hatch as a bird egg of similar size, says lead author Gregory Erickson, a paleobiologist at Florida State University in Tallahassee. But counts of growth lines on the teeth of rare fossilized dinosaur embryos from two species, Protoceratops andrewsi and Hypacrosaurus stebingeri, suggest a longer trajectory like that of reptiles, say Erickson and colleagues at the University of Calgary in Canada and the American Museum of Natural History in New York City. These lines, laid down daily on teeth, can be used like tree rings.
The longer incubation time might have worked against dinosaurs, Erickson says. Guarding a brood of eggs for many months could put parents at risk of attack. And a species hit by environmental catastrophe would have a harder time bouncing back.
Before an immature Zika virus becomes infectious, it does some major remodeling.
In a fledgling virus particle, the inner protein and RNA core (shown in dark blue above, right) forms bridges to the membrane layer that surrounds it. As the virus matures, the core shuffles around and the bridges melt away (below, right).
It’s the first time scientists have seen such rearrangement in the core of a flavivirus, the group that also includes the viruses that cause dengue, West Nile and yellow fever, says virologist Richard Kuhn of Purdue University in West Lafayette, Ind. Scientists don’t know why the immature Zika virus reshuffles its insides, Kuhn says — perhaps it helps the maturing virus become infectious. But that’s the next big question to answer, he says.
If blocking the reorganization somehow made mature viruses harmless, scientists would have a new clue about preventing Zika infection. Kuhn and colleagues’ map of the immature virus’s structure, published online January 9 in Nature Structural & Molecular Biology, could offer other hints for thwarting Zika.
With a technique called cryo-electron microscopy, the team could see three-headed protein spikes (shown in red) studding the surface like some kind of medieval weapon, and could even distinguish the separate layers of the membrane (aqua) that encloses the core. (The maps are radially colored; colors change as distance from the core increases.) Outside the membrane lie surface proteins called envelope, or E, proteins (green and yellow) that help the virus sneak into cells.
Last year, Kuhn’s team reported the structure of the mature Zika virus (SN: 4/30/16, p. 10). The new work offers another illuminating peek at Zika — a baby picture, of sorts.
Any exercise — even the weekend warrior approach, cramming it all into Saturday and Sunday — is better than none. Compared with inactive adults, those who got the recommended amount of weekly exercise, or even substantially less, had about a one-third lower risk of death during the study period, researchers report online January 9 in JAMA Internal Medicine.
Gary O’Donovan at the University of Leicester in England and colleagues analyzed data from 63,591 people ages 40 and older, surveyed between 1994 and 2012 as part of the Health Survey for England and the Scottish Health Survey. Adults should be getting 150 minutes of moderate activity (such as walking) or 75 minutes of vigorous activity (such as jogging) spread out across the week, according to the U.S. Centers for Disease Control and Prevention and the World Health Organization. Measured against people who did absolutely nothing, active people who worked up a sweat three or more times per week, weekend warriors and even those who moved less (60 minutes per week on average) all reduced their risk of dying early. The observational study can’t say that exercise caused the reduced risk, just that there’s an association.
