Subtle Ancient Footprints Come To Light
Eliene Augenbraun | November 29, 2019
Fossil footprints help tell us how ancient people lived. But such physical impressions are hard to find.
“You get all of these footprints from different species in the same time period interacting and you can't see them all the time and some of them you can never see, with the eye that is, but we can we can still detect them with geophysical sensors.”
Cornell University archaeologist Thomas Urban. He and colleagues used Ground Penetrating Radar (GPR) to detect invisible traces of footsteps in White Sands National Monument in New Mexico. Their GPR device goes back and forth over an area in a grid pattern, which ultimately creates a 2-D radargram. The technique detects subtle differences in ground density.
Speaking about one set of otherwise imperceptible animal’s footprints, he says: “These were caused by compression of sediment beneath the animals track and…they relate to the weight and momentum of the animal.”
Twelve-thousand-years ago, the White Sands area was a large muddy flat, which was covered with footprints from various species. Urban is excited about the stories so many footsteps suggest. For example, the researchers found no evidence of shoes or sandals. They did find human and animal tracks crossing each other—which suggests the prints were left during a hunt.
The findings are in the journal Scientific Reports. [Thomas M. Urban et al, 3-D radar imaging unlocks the untapped behavioral and biomechanical archive of Pleistocene ghost tracks]
“This sort of unique setting has recorded all of the daily movements of people…they're are actually more…than we even thought because there are always some that aren’t visible.”
These techniques could be applied to older sites all around the world, perhaps even to find dinosaur tracks that have been sitting quietly waiting at long last to be found.
Source: Scientific American
https://www.scientificamerican.com/podcast/episode/subtle-ancient-footprints-come-to-light/
[Rephrase 1, 02:00]
A new, theoretical type of time crystal could run without outside help
Emily Conover | November 27, 2019
[Time 2]
A newly proposed type of time crystal could stand alone.
Time crystals are structures that repeat regularly in time, just as a standard crystal is composed of atoms arranged in a regularly repeating pattern in space. Scientists first created time crystals in 2016. But those crystals require periodic blasts from a laser to initiate their rhythmic behavior.
Now, two scientists have sketched out a theoretical blueprint for a new version of the odd state of matter. Their time crystal would persist without any input from the outside world, the pair reports in the Nov. 22 Physical Review Letters.
First proposed in 2012 by theoretical physicists Frank Wilczek of MIT and Alfred Shapere of the University of Kentucky in Lexington, the idea of time crystals was initially controversial. Researchers soon proved a no-go theorem stating that, under typical conditions, time crystals couldn’t exist.
But wiggle room remained: Two situations not included in the no-go theorem left open the possibility of creating the unusual materials. One exception was systems for which energy is input from the outside, for example, via lasers. That’s what’s known in physics terminology as “driving” the system, and it’s how scientists had created all time crystals until now.
But theoretical physicists Oleksandr Kyriienko of the University of Exeter in England and Valerii Kozin of the University of Iceland in Reykjavik wanted to design a self-sustaining time crystal. “We said, ‘We don’t want to drive the system at all,’” Kyriienko says.
The pair exploited the second exception to the no-go rule — systems that involve very long-range interactions, in which atoms or other tiny particles separated by large distances could influence one another. Such long-range effects don’t typically occur in nature: Two atoms on opposite sides of a room normally don’t exert forces on one another, for example.
[298 words]
[Time 3]
Based on such interactions, the researchers came up with a new time crystal scenario, consisting of a collection of many such particles, each with a spin — a quantum version of angular momentum. Interactions between the particles’ spins would be configured so that particles near and far would influence one another simultaneously, via some unspecified quantum gymnastics in the laboratory. And particles in the time crystal would be highly entangled with one another, meaning they share quantum links that can persist at large distances.
Under such conditions, distant parts of the time crystal could affect one another. The result is that the correlation between the spins — whether neighboring particles’ spins were aligned or not — would endlessly oscillate in time in a regular pattern, producing a time crystal, the researchers say.
Scientists have typically studied systems of particles in which the interactions are short-range, or local. But researchers have long known that “something weird occurs once the locality is violated,” says physicist Haruki Watanabe of the University of Tokyo, one of the researchers who proved the no-go theorem. “So I wouldn’t be surprised by these kinds of behaviors of long-range interacting systems,” he says.
But it’s unclear whether such systems could be created in the laboratory. It’s not an easy feat to produce long-range interactions between many particles at once. “I don’t think it is possible to realize the long-range interacting system they proposed,” Watanabe says. But Shapere is optimistic, suggesting that scientists might use quantum computers or cold atoms to create the proposed time crystal or one like it.
When Wilczek and Shapere first came up with the idea of time crystals, the pair had envisioned a system that would operate without any outside input. “This paper brings us much closer to that original idea,” Shapere says.
[296 words]
Source: Science News
https://www.sciencenews.org/article/new-theoretical-type-time-crystal-could-run-without-outside-help
Critics say an EPA rule may restrict science used for public health regulations
Christopher Crockett | November 20, 2019
[Time 4]
In science, transparency is typically considered a virtue. But a rule proposed by the U.S. Environmental Protection Agency, billed as a means to keep environmental regulations rooted in reproducible science, is getting pushback from the scientific community.
The proposal, titled “Strengthening Transparency in Regulatory Science,” would require studies that factor into EPA rule-making to be based on publicly available data. Doing so, the agency argues, would ensure that other researchers could access that data and verify the findings of any study. The EPA administrator would be able to handpick allowances for studies whose data cannot be made public. But according to a Nov. 12 EPA news release, “this should be the exception instead of the way of EPA doing business.” That stipulation has some scientists worried that EPA regulations may then be able to ignore relevant evidence from many studies based on private information.
Among the critics are editors of six major scientific journals — Science, Nature, Cell, the Proceedings of the National Academy of Sciences, PLOS and the Lancet — who voiced their concerns in a statement published online November 26 in Science.
“We support open sharing of research data, but we also recognize the validity of scientific studies that, for confidentiality reasons, cannot indiscriminately share absolutely all data,” the authors write. Ignoring pertinent information in creating and updating policies like public health regulations simply because results are based on private data “would be a catastrophe.”
[235 words]
[Time 5]
The EPA is still hashing out the exact terms of its proposed policy, which was announced in April 2018 and will not be finalized until 2020. Science News spoke with Holden Thorp, editor in chief of the Science journals, and May Berenbaum, editor in chief of the Proceedings of the National Academy of Sciences, about the potential effects of the rule.
To what extent are scientific data already publicly available?
Much of the data underpinning scientific studies that could factor into government regulations is already publicly available. “However, in some cases, that is not possible,” Thorp says. “In those cases, [a scientific journal] would have a data agreement that would allow access to the data by other researchers on request” to reproduce or extend the original analysis.
Why can’t all data be made public?
Many investigations into environmental health risks, such as the effects of air pollution on asthma and other lung diseases, involve individuals’ health data. “Revealing the identity of people, particularly in the context of their health, has major ethical concerns,” Berenbaum says. Laws safeguarding patient privacy prohibit openly sharing that information.
Why can’t scientists just make sensitive data anonymous?
“It’s very hard to completely anonymize a dataset,” Thorp says. Even in datasets where names and other obvious identifiers like addresses have been redacted, remaining information can still be used to tease out participants’ identities.
It’s extremely difficult to find a balance between censoring enough detail to make data truly anonymous and leaving enough information behind to be useful for analysis, Thorp says.
[255 words]
[Time 6]
What’s the harm in discounting studies based on private data?
“Any time policies are made that are not evidence-based, then there’s all kinds of consequences,” Berenbaum says. “If you don’t use all available evidence, then you may remove some restrictions on pollution that the bulk of evidence suggests can lead to human health issues.”
For instance, regulations to protect people from toxic lead poisoning are informed by studies that involve privacy-sensitive health data, Thorp says.
“Certainly air and water pollution” regulations could be affected if confidential data are disqualified from consideration, Thorp says. “But I also think [of] climate change, because of the effects that climate change is having on public health in the U.S. and all around the world.… It’s hard to see that this would do anything other than weakening the policies that we have protecting the environment.”
How should the EPA balance transparency and privacy?
“We’ve done pretty well up to this point on using available data, and it seems like it’s in the best interest of the greatest number of people to continue using the best available data to inform science policy making,” Berenbaum says, even if that data sometimes has to remain confidential. “The process works, without having an absolute requirement for complete availability [of data] to everyone.”
[213 words]
Source: Science News
https://www.sciencenews.org/article/critics-say-epa-rule-may-restrict-science-public-health-regulations
New leaf-toed geckos found living on remote volcano
Jason G. Goldman| November 27, 2019
[Paraphrase 7]
The Galápagos Islands are already famous for their unique reptiles, from giant tortoises to rock-dwelling marine iguanas. Now, scientists have announced the discovery of three new geckos to add to the list—and one of them lives on a volcano.
A team of U.S. and Ecuadorian herpetologists recently found one of the leaf-toed geckos during a grueling expedition to Wolf Volcano, the most remote of the five volcanoes on Isabela, the largest island of the Galápagos archipelago.
"It takes a long, very expensive expedition, and once you get there you have to climb the slopes of the volcano, which takes a lot of effort, and a big team,” says herpetologist Alejandro Arteaga, director of science for the Ecuador-based research and ecotourism group Tropical Herping. The organization led a three-year effort to document every Galápagos reptile for the production of a first-ever field guide to the reptiles of the Ecuadorian archipelago.
When the team first set out for Wolf Volcano, their goal was not to look for geckos, but rather to photograph the volcano’s pink land iguana, a species only formally described about a decade ago, says Arteaga. Still, the researchers had a hunch that other reptiles in the area might also be novel species, so they decided to track down some geckos as well. (Read how an “extinct” tortoise in the Galápagos was rediscovered after a century.)
Their hunch proved prescient. They named the new species Sabin's leaf-toed gecko, or Phyllodactylus andysabini, after American philantropist Andrew Sabin, whose nonprofit foundation provided financial support for the expedition. Like all geckos in the genus Phyllodactylus, the toes of these lizards are reminiscent of ginkgo leaves. In all, the three-year project, funded by multiple international nonprofits, documented 12 species of leaf-toed geckos in the Galápagos—eleven of which are found there and nowhere else.
Such research is crucial because roughly half of the islands’ 48 reptile species are either threatened or already endangered, and knowing more about them and where they live can help scientists and governments shape more effective conservation strategies. For instance, P. andysabini’s entire range is just 96 square miles, making it vulnerable to lava flows (the most recent eruption occurred in 2015).
"When you combine this with the fact that there are still introduced predators in the area, especially cats and black rats," says Arteaga, "it definitely qualifies as endangered."
In the name of science
Sabin’s leaf-toed gecko, together with the pink iguana and a species of giant tortoise also isolated to Wolf Volcano, Chelonoidis becki, now makes three types of reptile endemic to northern Isabela. "Why northern Isabela is so special is a question no one can answer [yet]," says Arteaga.
Meanwhile, the second new species from Isabela, called Simpson's leaf-toed gecko, Phyllodactylus simpsoni, was first identified as a species following a 2014 expedition led by Ecuadorian herpetologist Omar Torres-Carvajal. Since he never published a formal description of the gecko, Arteaga and colleagues picked up where he left off, naming the species after Nigel Simpson, one of the founders of the Ecuadorian conservation organization Fundación Jocotoco, an expedition sponsors.
The third new species, the Mares leaf-toed gecko, Phyllodactylus maresi, isn't technically new, since it was described in 1973 as a subspecies of Phyllodactylus galapagensis. It was then named for Italian businessman Lodovico Mares, who funded the expedition that discovered the animal on a tiny islet also called Mares—named after the same individual—near Santiago Island. But the team’s sophisticated genetic sequencing has revealed the gecko is indeed its own species. (Read about Lonesome George, the last of the Pinta Island tortoises.)
What is puzzling is that the researchers found the Mares leaf-toed gecko both on Santiago Island and Marchena Island, which are separated by some 40 miles of ocean. Nobody knows which island the animal inhabited first, but genetic data reveals the second colonization happened recently, fewer than half a million years ago—which is not enough time for speciation to occur.
Sharing geckos with the world
To Tony Gamble, who was not involved in the research, it's not surprising that these geckos went undetected for so long. That's for a very simple reason: tourists and researchers alike are generally only allowed within the islands' protected areas during the day, and geckos are nocturnal.
"As soon as all the scientists and tourists leave, the sun goes down and the geckos come out. Based on their biology, [geckos] are particularly recalcitrant to study in the Galápagos," says Gamble, a herpetologist at Marquette University in Milwaukee. (Learn how geckos can turn their sticky feet on and off.)
Shining more light on these geckos and the plight of all Galápagos reptiles is actually why the scientists published Reptiles of the Galápagos both in print and as a free online download, rather than in a traditional scientific journal.
"One of our responsibilities is to translate science," says Lucas Bustamante, photography director for Tropical Herping, adding that many of the book’s funders made science communication a top priority for the research. "This is the future of environmental conservation," he adds.
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Source: National Geographic
https://www.nationalgeographic.com/animals/2019/11/new-gecko-species-ecuador-volcano/#close
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发表于 2019-12-4 19:58:53
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