Welcome to the Saturday Science Edition of Overnight News Digest
Overnight News Digest is a regular daily feature which provides noteworthy news items and commentary from around the world. The editorial staff includes side pocket, maggiejean, wader, Doctor RJ, rfall, and JML9999.
Neon Vincent is our editor-in-chief.
Special thanks go to Magnifico for starting this venerable series.
Astronomy
Alan Stern: What We Found at Pluto
Exactly 50 years to the day after Mariner 4 became the first mission to explore Mars, New Horizons completed the first era of planetary reconnaissance by flying past Pluto on July 14, 2015. In my final "insider blog" for SkyandTelescope.com, I want to give you a recap of the main findings that came from the initial data returned from the spacecraft. Regarding Pluto, we found a wonderland of diverse geological expression, with both old and young surfaces, mountain ranges, polygon-subdivided ice plains, flowing glaciers, and possibly even evidence for subsurface liquids. Pluto's mountains require strong materials to survive (and not slump) over time, indicating Pluto's crust is likely to be composed of water ice, rather than a deep layer of frozen nitrogen, which is soft and malleable to form long-lived mountains. We also found that Pluto was bigger — 2,374 km in diameter — than most past estimates. This larger true size, combined with Pluto's already well-known mass, means its true density is lower than we thought. So the ice fraction is higher (35% or 40%) and its rock fraction lower (60% or perhaps 65%). Meanwhile, its tenuous atmosphere has a base pressure of less than 10 microbars (about half what ground-based measurements had predicted), and it contains widespread hazes, several new molecular species (including acetylene and ethylene). skyandtelescope
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'Magnetic' Discovery May Reveal Why Earth Supports Life And Mars Doesn't
Earth's magnetic field, which protects the planet from harmful blasts of solar radiation, is much older than scientists had previously thought, researchers say. In fact, this invisible, protective shield likely existed shortly after the planet formed — a finding that could shed light on why Earth is habitable and Mars is not. Without Earth's magnetic field, solar winds — streams of electrically charged particles that flow from the sun — would strip away the planet's atmosphere and oceans. As such, Earth's magnetic field helped to make life on the planet possible, researchers have said. The magnetic field is generated by swirling liquid metal in Earth's outer core, and this "geodynamo" requires the release of heat from the planet to drive its churning. Nowadays, this heat flow is aided by plate tectonics — the movement of the plates of rock that make up the planet's exterior — which efficiently lets heat transfer from Earth's interior to its surface. [...]
"The oldest previously known magnetic field from a terrestrial planet was on Mars, which was older than 4 billion years old," [said John Tarduno, a geophysicist at the University of Rochester]. "But then, sometime after 4 billion years ago, it died off. If you compare the evolution of Earth and Mars, Mars had a more dense atmosphere, and water, but it probably lost both to erosion from the solar wind because it didn't have a magnetic field to protect them, whereas Earth always appeared to have had a strong magnetic shield."
space.com
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Biology
How A Single Molecule Turns One Immune Cell Into Another
Over the past 28 years, researchers have shown that a number of specialized cell types can be forcibly converted into another, but the science of how this change takes place is still emerging. Such transdifferentiations, as they're called, include turning a skin cell into a muscle cell (or a muscle cell into a brown fat cell) with the addition of just one or two transcription factors. These are molecules that bind to a cell's DNA and cause other genes to be expressed.
"For a long time it was unclear whether forcing cell fate decisions by expressing transcription factors in the wrong cell type could teach us something about what happens normally during physiological differentiation," says senior study author Thomas Graf of the Center for Genomic Regulation in Spain. "What we have now found is that the two processes are actually surprisingly similar."
Based on experiments led by the first author of the study, Chris van Oevelen, B cell transdifferentiation takes place when C/EBPa binds to two regions of DNA that act as gene expression enhancers. Whereas one of these regions is normally active in immune cells, the other is only turned on when macrophage precursors are ready to differentiate. This indicates that the convergence of these two enhancer pathways can cause the B cell to act like a macrophage precursor, thus triggering the unnatural transdifferentiation. biologynews.net
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3-D–Printed Flowers Lure Invasive Weevils To Their Deaths In Wisconsin
There's something particularly cruel in using beauty to kill, but that's exactly what scientists at the Chicago Botanic Garden set out to do earlier this summer in the sand dunes of northern Wisconsin. There Kayri Havens and her colleagues planted about 60 3-D-printed flowers to lure invasive weevils to their death. For more than a decade, beginning in the 1990s, scientists deliberately distributed the invasive weevil Larinus planus throughout the country to consume Canada thistle, an aggressive weed that had run rampant through American farm fields and rangeland. But like many well-intentioned species-control efforts before it, the plan went awry. The long-snouted insect jumped host and attacked native thistles, including the Pitcher's thistle, a flowering spiky plant that grows only in the Great Lakes region and was listed as a threatened species in 1988 by the U.S. Fish and Wildlife Service in response to habitat destruction. Left to its own devices, the seed-eating weevil could cut the Pitcher thistle's possible time to extinction in half, Havens says. She now hopes the 3-D-printed thistle fakes will come to control the biocontrols. The plastic purple, blue or white flowers—some halfway open, others in full bloom—sit atop 20-inch-long dowels alongside the real things on Wisconsin's Door County peninsula. Most are outfitted with cotton wicks saturated in a lemony or wintergreen scent, both known to attract weevils. “We needed a chemical signature that weevils go crazy over,” says botanist Pati Vitt. Video cameras currently capture faunal activity at the faux-studded floral plots so researchers can catalogue which models the weevils favor, the number of insects that visit and how long they stay. Once the scientists discern the shape, color and smell combo that attracts the weevils—but not bees and other pollinators—a trap will be designed. It could take a few years to determine all the particulars, so for now the weevils that take a shine to the 3-D-printed blooms are captured by hand when possible and thrown in soapy water to die. If the counterfeit scheme works, fields of 3-D-printed flowers might one day stand guard over Wisconsin's dunes. scientificamerican.com
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Chemistry
Stone 'Blueprinting' To Tackle Heritage Thefts
A combined laser and chemical ‘blueprinting’ technique could help crackdown on the growing problem of stone theft from heritage sites, according to researchers at Loughborough University, UK. There has been a significant increase in stone thefts in rural parts of the UK in recent years, to the extent that it prompting the problem to be recently debated in the House of Commons. A recent survey indicates that stone has become the third most popular target for thieves at heritage sites in the UK, just behind copper and lead. Currently, a major barrier that the police face when working on stone theft cases is trying to trace unmarked stone after it’s already been sold. This new technique, which involves extracting a chemical 'blueprint' from stone using a gelatine sheet and then scanning the sample using laser induced breakdown spectroscopy (LIBS), offers hope of helping to solve such crimes. In the past, the team has successfully demonstrated that this combination of LIBS and gelatine lift can detect metal theft and create a map of metal traces left on a suspect’s hands. The approach that the team is testing could ultimately lead the researchers to enter their results into a national database, providing an indication of where that sample originated from. This could offer a useful point of reference from which to tackle stone theft. rsc.org
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Suspected Meth Lab Explodes At National Institute Of Standards & Technology
Congress is among the investigators probing a July 18 explosion of a suspected methamphetamine lab at the National Institute of Standards & Technology near Washington, D.C. The explosion injured a NIST security officer, according to local police investigating the incident along with the federal Drug Enforcement Administration. The security officer was treated for injuries and released from a local trauma center. He then resigned from NIST effective July 19, police say. They add that evidence recovered from the explosion is consistent with production of the illicit synthetic drug methamphetamine.
“The fact that this explosion took place at a taxpayer-funded NIST facility, potentially endangering NIST employees, is of great concern,” says Rep. Lamar S. Smith (R-Texas), chairman of the Science, Space & Technology Committee in the U.S. House of Representatives. Smith is asking Secretary of Commerce Penny Pritzker to supply as much information as possible to his panel about the explosion before the end of July. NIST is part of the Commerce Department. “I am troubled by the allegations that such dangerous and illicit activity went undetected at a federal research facility,” Smith says, adding that he wants to, "...ensure that researchers at federal laboratories are safe."
acs.org
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Earth Science
Greenhouse Gas Emissions From US Corn Belt Have Been Underestimated
Estimates of how much nitrous oxide, a significant greenhouse gas and stratospheric ozone-depleting substance, is being emitted in the central United States have been too low by as much as 40 percent, a new study led by University of Minnesota scientists shows. The study, published today in the journal Proceedings of the National Academy of Sciences, measured how much nitrous oxide is emitted from streams in an agriculturally dense area in southern Minnesota. Agriculture, and specifically nitrogen fertilizers used in row-crop farming, is a major contributor to nitrous oxide emissions from streams, the paper notes. [...] The researchers found that some of the discrepancies between bottom-up emission measurements and those taken from the air can be attributed to variations in the size and flow of streams and rivers; by taking the impact of stream networks into account, scientists can more accurately estimate and mitigate increased concentrations of nitrous oxide. A strong relation was observed between the emission strength of a stream and its size, known as stream order. The smallest streams, or those with the closest connections to the land, were the strongest sources. The researchers hypothesize that this is a consequence of both high nitrogen loading and higher turbulent exchange rates. As stream size increases, the potential of these processes to produce large emissions is diminished. These two mechanisms acting together help explain why headwater streams are such strong sources. The findings suggest that nitrous oxide emissions from rivers have been underestimated by the IPCC (Intergovernmental Panel on Climate Change) by as much as nine-fold. By properly accounting for the emission factor of these sources, much of the difference between bottom-up and top-down approaches can be resolved. enn.com
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World Population Expected To Reach 9.7 Billion By 2050
People of the future will need to learn to love their neighbors. The latest predictions for population growth from the United Nations indicate the Earth will be more crowded than previously thought. The global population is currently about 7.3 billion. The UN estimates that by 2050, that number will grow to 9.7 billion. By 2100, 11.2 billion people will have to cram together on the Earth’s surface. [...] There’s some wiggle room, though. The UN says there’s an 80 percent chance that the population could be as low as 9.4 or as high as 10 billion in 2050. The agency is basing this on a formula called the ‘medium projection variant,’ which basically assumes that the fertility patterns of the future will resemble those of the past. It’s not an increase in fertility that’s driving the growth. It’s longer lifespans. Globally, people born today are expected to live to age 70, but people born in 2050 will live to age 77. Their grandkids born in 2100 will live even longer: 83 years. nationalgeographic.com
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Physics
Here's Why Scientists Haven't Invented An Impossible Space Engine – Despite What You May Have Read
What if I told you that recent experiments have revealed a revolutionary new method of propulsion that threatens to overthrow the laws of physics as we know them? That its inventor claims it could allow us to travel to the Moon in four hours without the use of fuel? What if I then told you we cannot explain exactly how it works and, in fact, there are some very good reasons why it shouldn't work at all? I wouldn't blame you for being sceptical.The somewhat fantastical EMDrive (short for Electromagnetic Drive) recently returned to the public eye after an academic claimed to have recorded the drive producing measurable thrust. The experiments from Professor Martin Tajmar's group at the Dresden University of Technology have spawned numerous overexcited headlines making claims that –- let's be very clear here –- are not supported by the science.The idea for the EMDrive was first proposed by Roger Shawyer in 1999 but, tellingly, he has only recently published any work on it in a peer-reviewed scientific journal, and a rather obscure one at that. Shawyer claims his device works by bouncing microwaves around inside a conical cavity. According to him, the taper of the cavity creates a change in the group velocity of the microwaves as they move from one end to the other, which leads to an unbalanced force, which then translates into a thrust. If it worked, the EMDrive would be a propulsion method unlike any other, requiring no propellant to produce thrust. Fundamental problems There is, of course, a flaw in this idea. The design instantly violates the principle of conservation of momentum. This states the total momentum (mass x velocity) of objects in a system must remain the same and is linked to Newton's Third Law. Essentially, for an object to accelerate in one direction, there must be an equal force directed the opposite way. In the case of engines, this usually means firing out particles (such as propellant) or radiation.The EMDrive is designed to be a closed system that doesn't emit any particles or radiation. It cannot possibly generate any thrust without breaking some seriously fundamental laws of physics. To put it bluntly, it's like trying to pull yourself up by your shoelaces and hoping you'll levitate.From Earth to the Moon in four hours? Still impossible. ShutterstockNonetheless, a few open-minded experimental groups have built prototype EMDrives and all seem to see it generate some form of thrust. This has led to a lot of excitement. Maybe the laws of physics as we know them are wrong?Eagleworks, a NASA-based group, built a prototype and last year reported 30-50 micronewtons of thrust that could not be explained by any conventional theory. This work was not peer-reviewed. Now, Tajmar's group in Dresden say they have built a new version of the EMDrive and detected 20 micronewtons of thrust. This is a much smaller value, but still significant if it really is generated by some new principle. phys.org
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Stretchable Graphene Transistors Inspired By Kirigami
A stretchable and bendable transistor has been made by researchers in the US by applying the principles of kirigami – the Japanese art of paper cutting – to graphene. The researchers have also made tiny graphene-based hinges and pyramids, and they are confident that they could reduce the size of their devices to the nanometre scale. The team also points out that the current micro-scale devices could be useful for biocompatible electronics, including probes for the study of neurons. The mainstay of the electronics industry, silicon, is rigid and brittle, and is therefore not appropriate for making deformable electronics. The ability to deform is particularly useful for electronic devices that interface with biological organisms, for example sensitive prosthetic skin and subcutaneous sensors, which must bend and stretch with surrounding tissue. Graphene is a flexible sheet of carbon just one atom thick, and could offer a way to create deformable electronics because of its high electrical conductivity. One problem with graphene, however, is that it stretches very little. Nanoscientist Paul McEuen and colleagues at Cornell University in Ithaca, New York, were inspired to try graphene kirigami after they investigated the bending stiffness of the material. They used an infrared laser beam to press on a gold pad located on the tip of a graphene cantilever that is about 10 μm long. By measuring the displacement in response to the known force of the laser photons, they calculated the bending stiffness of the material. They also monitored the thermal oscillations of a graphene cantilever and calculated the stiffness from the oscillation amplitude. physicsworld.com
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