Earth

UK Steps Towards Zero-Carbon Economy (bbc.com) 240

The UK is taking a tentative step towards a radical "green" future with zero emissions of greenhouse gases. From a report: The government is formally seeking Climate Change Committee (CCC) guidance about how and when to make this leap. If it happens it would mark an extraordinary transformation of an economy built on burning fossil fuels. The decision was prompted by last week's UN report warning that CO2 emissions must be stopped completely to avoid dangerous climate disruption.

Climate minister Claire Perry told BBC News: "The report was a really stark and sober piece of work -- a good piece of work. "Now we know what the goal is and we know what some of the levers are. But for me, the constant question is what is the cost and who's going to bear that, both in the UK and in the global economy. The question is: what does government need to do, where can the private sector come in, and what technologies will come through?"

Ms Perry has declared this week to be Green GB Week, which aims to raise debate in society about how to tackle climate change while also growing the economy. The UK's current target is a reduction of 80% of emissions by 2050 based on 1990 levels. But the CCC is warning that the UK will drift further away from this goal unless new policies are introduced.

Stats

Struggle With Statistics? Your 'Fixed Mindset' Might Be To Blame (arstechnica.com) 151

A new study in Frontiers in Psychology examined why people struggle so much to solve statistical problems, particularly why we show a marked preference for complicated solutions over simpler, more intuitive ones. Chalk it up to our resistance to change. From a report: The study concluded that fixed mindsets are to blame: we tend to stick with the familiar methods we learned in school, blinding us to the existence of a simpler solution. Roughly 96 percent of the general population struggles with solving problems relating to statistics and probability. Yet being a well-informed citizen in the 21st century requires us to be able to engage competently with these kinds of tasks, even if we don't encounter them in a professional setting. "As soon as you pick up a newspaper, you're confronted with so many numbers and statistics that you need to interpret correctly," says co-author Patrick Weber, a graduate student in math education at the University of Regensburg in Germany. Most of us fall far short of the mark.

Part of the problem is the counterintuitive way in which such problems are typically presented. Meadows presented his evidence in the so-called "natural frequency format" (for example, 1 in 10 people), rather than in terms of a percentage (10 percent of the population). That was a smart decision, since 1-in-10 a more intuitive, jury-friendly approach. Recent studies have shown that performance rates on many statistical tasks increased from four percent to 24 percent when the problems were presented using the natural frequency format.

Medicine

Scientists Are Getting Seriously Worried About Synthetic Smallpox (sciencealert.com) 93

An anonymous reader quotes ScienceAlert: Earlier this year, scientists published a paper describing how they pieced together segments of DNA in order to bring back a previously eradicated virus called horsepox. The paper, written by two University of Alberta researchers and the co-founder of a New York pharmaceutical company, was controversial because, as various experts told the magazine Science, someone could use a very similar process to bring back a related virus: smallpox. Smallpox, you'll recall, killed hundreds of millions of people before the World Health Organization declared it eradicated in 1980. That was the result of a long vaccination campaign — so the idea of piecing the virus back together from bits of DNA raises the specter of a horrifying pandemic.

Two journals rejected the paper before PLOS One, an open access peer-reviewed journal, published it. Critics argue that the paper not only demonstrates that you can synthesize a deadly pathogen for what Science reported was about US$100,000 in lab expenses, but even provides a slightly-too-detailed-for-comfort overview of how to do it. Some of the horsepox scientists' coworkers are still pretty upset about this. PLOS One's sister Journal, PLOS Pathogens, just published three opinion pieces about the whole flap, as well as a rebuttal by the Canadian professors. Overall, everyone's pretty polite. But you get the sense that microbiologists are really, really worried about someone reviving smallpox. MIT biochemist Kevin Esvelt, for instance, wrote on Thursday that the threat is so grim that we shouldn't even talk about it.

Space

Stephen Hawking's Last Paper Is Now Online (vice.com) 70

An anonymous reader quotes a report from Motherboard: When Stephen Hawking died in March at the age of 76, the world mourned a beloved and visionary scientist. But it is some consolation that Hawking's final paper has now been published on the preprint journal ArXiv, demonstrating that even during his last days, he was still pursuing the epic cosmic questions that defined his career. Entitled "Black hole entropy and soft hair," the paper was authored by Hawking along with physicists Sasha Haco, Malcolm Perry, and Andrew Strominger. The work is the third in a series from the team and addresses Hawking's famous brainchild -- the black hole information paradox. Like many physics conundrums, the paradox emerges from the lack of coherence between quantum field theory and general relativity. On the smallest scales of matter, where atoms and quarks abound, there exists a different and seemingly contradictory set of rules to the largest scale of matter, involving stars and galaxies. The search for a "theory of everything" that reconciles these two models is one of the holy grails of modern physics, and was a lifelong fascination for Hawking.

Black holes are notable flashpoints for this tension between quantum field theory and general relativity. According to the quantum rulebook, it should be impossible for information about a particle -- its spin, configuration, mass, and other features -- to be permanently deleted from the universe. But what about matter that falls into black holes, objects with a reputation of not letting anything escape once it passes the event horizon? Can information be scrubbed inside black holes? Hawking suggested that information could indeed be deleted through Hawking radiation, which is a type of theoretical radiation that can escape from inside a black hole. This process has never been empirically observed, but the radiation would supposedly be stripped of all information about its original properties -- and that would violate the rules of the universe as we know them. In his last paper, Hawking and his colleagues speculated that a phenomenon called "soft hair" might resolve the black hole information paradox. The idea is that trails of light and gravity particles might encircle the event horizon, and could store, at the very least, entropic information about matter that fell into the black hole.

AI

Google AI Claims 99 Percent Accuracy In Metastatic Breast Cancer Detection 34

Researchers at the Naval Medical Center San Diego and Google AI, a division within Google dedicated to artificial intelligence research, are using cancer-detecting algorithms to detect metastatic tumors by autonomously evaluating lymph node biopsies. VentureBeat reports: Their AI system -- dubbed Lymph Node Assistant, or LYNA -- is described in a paper titled "Artificial Intelligence-Based Breast Cancer Nodal Metastasis Detection," published in The American Journal of Surgical Pathology. In tests, it achieved an area under the receiver operating characteristic (AUC) -- a measure of detection accuracy -- of 99 percent. That's superior to human pathologists, who according to one recent assessment miss small metastases on individual slides as much as 62 percent of the time when under time constraints. LYNA is based on Inception-v3, an open source image recognition deep learning model that's been shown to achieve greater than 78.1 percent accuracy on Stanford's ImageNet dataset. As the researchers explained, it takes as input a 299-pixel image (Inception-v3's default input size), outlines tumors at the pixel level, and, in the course of training, extracts labels -- i.e., predictions -- of the tissue patch ("benign" or "tumor") and adjusts the model's algorithmic weights to reduce error.

In tests, LYNA achieved 99.3 percent slide-level accuracy. When the model's sensitivity threshold was adjusted to detect all tumors on every slide, it exhibited 69 percent sensitivity, accurately identifying all 40 metastases in the evaluation dataset without any false positives. Moreover, it was unaffected by artifacts in the slides such as air bubbles, poor processing, hemorrhage, and overstaining. LYNA wasn't perfect -- it occasionally misidentified giant cells, germinal cancers, and bone marrow-derived white blood cells known as histiocytes -- but managed to perform better than a practicing pathologist tasked with evaluating the same slides. And in a second paper published by Google AI and Verily, Google parent company Alphabet's life sciences subsidiary, the model halved the amount of time it took for a six-person team of board-certified pathologists to detect metastases in lymph nodes.
Science

World's Fastest Camera Shoots 10 Trillion Frames a Second (newatlas.com) 62

bbsguru shares a report from New Atlas: Slow-motion video has always been fun to watch, with the best rigs usually shooting on the scale of thousands of frames per second. But now the world's fastest camera, developed by researchers at Caltech and INRS, blows them out of the water, capturing the world at a mind-boggling 10 trillion frames per second -- fast enough to probe the nanoscale interactions between light and matter. For the new imaging technique, the team started with compressed ultrafast photography (CUP), a method that it is capable of 100 billion fps. That's nothing to scoff at by itself, but it's still not fast enough to really capture what's going on with ultrafast laser pulses, which occur on the scale of femtoseconds. A femtosecond, for reference, is one quadrillionth of a second.

So the team built on that technology by combining a femtosecond streak camera and a static camera, and running it through a data acquisition technique known as Radon transformation. This advanced system was dubbed T-CUP. For the first test, the camera proved its worth by capturing a single femtosecond pulse of laser light, recording 25 images that were each 400 femtoseconds apart. Through this process, the team could see the changes in the light pulse's shape, intensity and angle of inclination, in much slower motion than ever before.

NASA

Scientists Have Laid Out a Plan To Search For Life in the Universe (qz.com) 59

An anonymous reader shares a report: A blue-ribbon panel of researchers chaired by the University of Toronto's Barbara Sherwood Lollar assembled the report at the behest of the US Congress, which asked in a 2017 law that a "strategy for astrobiology" be developed to prioritize "the search for life's origin, evolution, distribution, and future in the universe." The 196-page report does not offer easy access to ET, but the steady drumbeat of scientific advancement it documents suggests an increasingly sophisticated understanding of what we know -- and don't know -- about biology on our planet and beyond.

Indeed, the recently gained knowledge it highlights is the front end of a wave: Only the Viking mission in the 1970s hunted rigorously for signs of life on other planets, and now the first new NASA mission to do so, the Europa lander, is being designed. In the past four years alone, scientists using data gathered by space probes on Mars discovered evidence of past surface water, the presence of nutrients and organic molecules, and methane gas in the atmosphere that varies by season. This doesn't mean life exists now on Mars, but it is helping contribute to an understanding of astrobiology as a discipline that looks at physical and chemical processes over time to determine if the conditions for life once existed or may do so in the future.

Much work on astrobiology is Earth-focused; it is the only place we know life exists and thus is our guinea pig for detecting life from a distance. The Galileo space probe found signs of life on our planet in 1990. The report stressed that recent discoveries of life on Earth that exists without the sun's energy, deep under the ocean or the ground, should inform what we look for on other worlds. Scientists are expanding their understanding of habitability beyond a binary and into a spectrum, which may sound trite, but previous research relied on blunt instruments and blunter assumptions about alien life -- starting with the idea that it would appear on the surface.

Earth

Bees Stop Flying During Total Solar Eclipses (smithsonianmag.com) 86

A new study published by the Entomological Society of America found that bees stop flying when the moon obstructs the sun during a total solar eclipse. "Using tiny microphones suspended among flowers, the team recorded the buzzing of the bees through all stages of the eclipse," reports Smithsonian Magazine. "The bees were active and noisy right up to the last moments before totality, the part of a total solar eclipse when the moon blocks all direct sunlight, and a night-like darkness settles over the land. As totality hit, the bees went totally silent in unison." From the report: The clear drop from buzzing to silence was the most striking change during the eclipse, but additional, smaller changes in the bees' buzzing could give the researchers clues about how the insects responded. As ecologist Candace Galen of the University of Missouri notes, the bees' buzzes lasted longer as it gradually got darker approaching totality. Increased buzz length suggests the bees started flying more slowly, they were taking longer flights, or some combination of both.

"The way I think about it is, if you're driving on a road and it gets foggy, you slow down," explains Galen. When there is less visibility, slowing down helps you process information and maintain situational awareness -- and like the bees did during totality, if there's absolutely zero visibility, you should probably pull over. Adjusting speed to acclimate one's senses to an environment that suddenly shifts is a common behavior in many animals, and it's been observed in bees when they fly before sunrise or sunset.

Science

Self-Healing Material Can Build Itself From Carbon In the Air (mit.edu) 63

MIT chemical engineers have reportedly designed a material that can react with carbon dioxide from the air, "to grow, strengthen, and even repair itself." According to MIT News, "The polymer, which might someday be used as construction or repair material or for protective coatings, continuously converts the greenhouse gas into a carbon-based material that reinforces itself." From the report: The current version of the new material is a synthetic gel-like substance that performs a chemical process similar to the way plants incorporate carbon dioxide from the air into their growing tissues. The material might, for example, be made into panels of a lightweight matrix that could be shipped to a construction site, where they would harden and solidify just from exposure to air and sunlight, thereby saving on the energy and cost of transportation. The material the team used in these initial proof-of-concept experiments did make use of one biological component -- chloroplasts, the light-harnessing components within plant cells, which the researchers obtained from spinach leaves. The chloroplasts are not alive but catalyze the reaction of carbon dioxide to glucose. Isolated chloroplasts are quite unstable, meaning that they tend to stop functioning after a few hours when removed from the plant. In their paper, [the researchers] demonstrate methods to significantly increase the catalytic lifetime of extracted chloroplasts. In ongoing and future work, the chloroplast is being replaced by catalysts that are nonbiological in origin.

The material the researchers used, a gel matrix composed of a polymer made from aminopropyl methacrylamide (APMA) and glucose, an enzyme called glucose oxidase, and the chloroplasts, becomes stronger as it incorporates the carbon. It is not yet strong enough to be used as a building material, though it might function as a crack filling or coating material, the researchers say. The team has worked out methods to produce materials of this type by the ton, and is now focusing on optimizing the material's properties. Commercial applications such as self-healing coatings and crack filling are realizable in the near term, they say, whereas additional advances in backbone chemistry and materials science are needed before construction materials and composites can be developed.

China

Scientists Create Healthy Mice With Same-Sex Parents (bbc.com) 183

Researchers at the Chinese Academy of Sciences were able to make baby mice with two moms and no dad. "The aim of the Chinese researchers was to work out which rules of reproduction they needed to break to make baby mice from same-sex parents," reports the BBC. "That in turn helps understand why the rules are so important." From the report: It was easier with double mums. The researchers took an egg from one mouse and a special type of cell -- a haploid embryonic stem cell -- from another. Both contained only half the required genetic instructions or DNA, but just bringing them together wasn't enough. The researchers had to use a technology called gene editing to delete three sets of genetic instructions to make them compatible (more on that later). The double-dad approach was slightly more complicated. It took a sperm, a male haploid embryonic stem cell, an egg that had all of its own genetic information removed and the deletion of seven genes to make it all work.

The reason we need to have sex is because our DNA -- our genetic code -- behaves differently depending on whether it comes from mum or dad, the study in Cell Stem Cell suggests. And without a female copy and a male copy our whole development gets thrown out of whack. It's called genomic imprinting with parts of the DNA in sperm and parts of the DNA in eggs getting different "stamps" that alter how they work. The bits of DNA carrying these stamps were the ones the researchers had to delete in order to make the baby mice viable.

News

Researchers Develop 3D Printed Objects That Can Track and Store How They Are Used (washington.edu) 16

Researchers at the University of Washington have developed 3D printed assistive technology that can track and store their use -- without using batteries or electronics. From a blog post on University of Washington: Cheap and easily customizable, 3D printed devices are perfect for assistive technology, like prosthetics or "smart" pill bottles that can help patients remember to take their daily medications. But these plastic parts don't have electronics, which means they can't monitor how patients are using them. Now engineers at the University of Washington have developed 3D printed devices that can track and store their own use -- without using batteries or electronics. Instead, this system uses a method called backscatter, through which a device can share information by reflecting signals that have been transmitted to it with an antenna.

"We're interested in making accessible assistive technology with 3D printing, but we have no easy way to know how people are using it," said co-author Jennifer Mankoff, a professor in the UW's Paul G. Allen School of Computer Science & Engineering. "Could we come up with a circuitless solution that could be printed on consumer-grade, off-the-shelf printers and allow the device itself to collect information? That's what we showed was possible in this paper."
The UW team will present its findings next week at the ACM Symposium on User Interface Software and Technology in Berlin.
Crime

How Genealogy Websites Make It Easier To Catch Killers (ieee.org) 73

An anonymous reader quotes a report from IEEE Spectrum: Over the past six months a small, publicly available genealogy database has become the go-to source for solving cold case crimes. The free online tool, called GEDmatch, is an ancestry service that allows people to submit their DNA data and search for relatives -- an open access version of AncestryDNA or 23andMe. Since April, investigators have used GEDmatch to identify victims, killers, and missing persons all over the U.S. in at least 19 cases, many of them decades old, according to authors of a report published today in Science. The authors predict that in the near future, as genetic genealogy reports gain in popularity, such tools could be used to find nearly any individual in the U.S. of European descent.

GEDmatch holds the genetic data of only about a million people. But cold case investigators have been exploiting the database using a genomic analysis technique called long-range familial search. The technique allows researchers to match an individual's DNA to distant relatives, such as third cousins. Chances are, one of those relatives will have used a genetic genealogy service. More than 17 million people have participated in these services -- a number that has grown rapidly over the last two years. AncestryDNA and 23andMe hold most of those customers. A genetic match to a distant relative can fairly quickly lead investigators to the person of interest. In a highly publicized case, GEDmatch was used earlier this year to identify the "Golden State Killer," a serial rapist and murderer who terrorized California in the 1970s and 1980s, but was never caught.
In April, investigators were able to use a genealogy database to narrow down DNA data from crime scenes and identify the "Golden State Killer," a serial rapist and murderer who terrorized California in the 1970s and 1980s.
Moon

Moons Can Have Their Own Moons and They Could Be Called Moonmoons (atlasobscura.com) 168

Two astronomers have asked a question for the ages: Can moons have moons? The delightful, if theoretical, answer is: Yes -- yes, they can. Sarah Laskow, writing for Atlas Obscura: As Gizmodo reports, this particular scientific inquiry began with a question from Juna Kollmeier's son. Kollemeier, who works at the Observatories of the Carnegie Institution of Washington, recruited Sean Raymond, of the University of Bordeaux, to help her answer the question. In a paper posted on arXiv [PDF], they lay out their case that moons can have moons. The conditions have to be right -- the primary moon has to be big enough and far away enough from the planet it's orbiting for the smaller, secondary moon to survive. But, even given these caveats, they found that moons in our very own solar system could theoretically have their own smaller moons. Two of Saturn's moons and one of Jupiter's are candidates. So is our favorite moon -- the Earth's moon.

[...] One of the great challenges of talking about recursive places is deciding what call them. The prefix "sub-" can do a lot of work here: We can islands within islands "subislands," and in the arXiv paper, Kollmeier and Raymond call a moon's moon a "submoon." But there are other options. New Scientist notes that "moonmoon" has been put forth as a name for a moon's moon. For those of us who are less than fluent in meme culture: This is a reference to Moon Moon, sometimes described as the internet's derpiest wolf. Moon Moon was born in 2013, from a werewolf name generator, and soon started frolicking across Tumblr and all other places memes can be found.

Science

Huge Reduction in Meat-Eating 'Essential' To Avoid Climate Breakdown (theguardian.com) 629

Huge reductions in meat-eating are essential to avoid dangerous climate change, according to the most comprehensive analysis yet of the food system's impact on the environment. From a report: In western countries, beef consumption needs to fall by 90% and be replaced by five times more beans and pulses. The research [PDF] also finds that enormous changes to farming are needed to avoid destroying the planet's ability to feed the 10 billion people expected to be on the planet in a few decades. Food production already causes great damage to the environment, via greenhouse gases from livestock, deforestation and water shortages from farming, and vast ocean dead zones from agricultural pollution. But without action, its impact will get far worse as the world population rises by 2.3 billion people by 2050 and global income triples, enabling more people to eat meat-rich western diets.
The Military

The Military Chooses Which Rockets It Wants Built For the Next Decade (arstechnica.com) 107

The U.S. Air Force on Wednesday awarded funds to three rocket companies to help them complete development of their boosters. The three winners include:

United Launch Services: $967,000,000 for the development of the Vulcan Centaur launch system.
Northrop Grumman: $791,601,015 for development of the Omega launch system
Blue Origin: $500,000,000 for the development of the New Glenn launch system

The obvious company missing from the list is SpaceX, which did not win an award. Aerojet Rocketdyne also failed to win an award since it "does not appear to have a customer for its AR1 rocket engine, which the military initially supported," Ars Technica reports. From the report: These are hugely consequential awards for the rocket companies. Essentially the U.S. Air Force, which launches more complex, heavy payloads than any other entity in the world, believes these boosters will have a significant role to play in those missions during the next decade. And when the military has confidence in your vehicle, commercial satellite contracts are more likely to follow as well. After speaking with a couple of aerospace sources, Ars has a few theories as to why SpaceX didn't win an award: For one, SpaceX has already built and flown a rocket that can reach all of the Air Force's reference orbits -- the Falcon Heavy. Moreover, the Falcon Heavy is already certified for the Air Force and has won contracts. Air Force officials may also feel that, through NASA contracts for commercial cargo and crew, the government already facilitated development of the Falcon Heavy -- which uses three Falcon 9 rocket cores. It also depends upon what SpaceX bid for. The government would have been more inclined to fund development of an advanced upper stage for the Falcon Heavy or vertical integration facilities. But it seems like the military would not have been as interested in the Big Falcon Rocket, which is more booster than it deems necessary at this time. So if SpaceX bid the BFR, that is one possible explanation for no award.
Earth

Newly Discovered Volcanic 'Lost World' Is a Haven For Marine Life (gizmodo.com) 47

An anonymous reader quotes a report from Gizmodo: Australian scientists have discovered a previously unknown chain of volcanic seamounts near Tasmania. The area appears to be brimming with marine life, including a surprising number of whales who may be using the undersea volcanoes as a navigational tool. The volcanic chain was discovered by scientists from the Australian National University and CSIRO, Australia's national science agency, while on a 25-day mission aboard the research vessel Investigator to conduct detailed seafloor maps of the region. The undersea volcanoes are about 250 miles (400 kilometers) east of Tasmania, and they're quite deep.

The tallest of the seamounts extends 3,000 meters (9,800 feet) from the seafloor, so they're not tiny. It's hard to believe that something so large has gone undetected for so long, but our oceans are notoriously understudied. A mere 20 percent of Earth's oceans has been explored, according to the National Oceanic and Atmospheric Administration. [T]he seamounts appeared to serve as a kind of mid-ocean oasis for a host of marine organisms. In addition to finding copious amounts of plankton in the area, the researchers observed various seabirds and a surprising number of whales. The volcanic seamounts, the researchers say, are likely important stopping points for migratory animals, particularly whales, who rely on seafloor structures for navigation. The volcanoes are likely serving as important signposts as the whales travel from their winter breeding areas to summer feeding grounds, the researchers say.

Medicine

Amazon Patents New Alexa Feature That Knows When You're ill and Offers To Sell You Medicine (telegraph.co.uk) 59

Amazon has patented a new version of its virtual assistant Alexa which can automatically detect when you're ill and offer to sell you medicine. From a report: The proposed feature would analyse speech and identify other signs of illness or emotion. One example given in the patent is a woman coughing and sniffling while she speaks to her Amazon Echo device. Alexa first suggests some chicken soup to cure her cold, and then offers to order cough drops on Amazon. If Amazon were to introduce this technology, it could compete with a service planned by the NHS. Health Secretary Matt Hancock said earlier this year that the NHS was working on making information from its NHS Choices online service available through Alexa. Amazon's system, however, doesn't need to ask people whether they're ill -- it would just know automatically by analyzing their speech. Adverts for sore throat products could be automatically played to people who sound like they have a sore throat, Amazon's patent suggests.
Space

There Could Be Massive Shards of Ice Sticking Out of Jupiter's Moon Europa (sciencealert.com) 63

According to a report published in the journal Nature Geoscience, Jupiter's Moon Europa may be home to a forest of tall, jagged ice spikes, which may complicate future missions looking for possible alien microbes. ScienceAlert reports: Few moons in the Solar System are as intriguing as Jupiter's moon Europa. A global ocean of salt water almost certainly surrounds the moon - and it holds more water than any ocean on Earth. Above this immense sea, where surface temperatures dip to minus 300 degrees Fahrenheit (-184 degrees Celsius), a crust of water ice forms a shell. Astronomers predict that Jupiter, which bombards the moon with intense radiation, causes the entire moon to groan with gravity's tug. Europa's liquid water is a tempting target for future missions looking for possible alien microbes. But before a future lander can search for microscopic ET, the probe might have to contend with a forest of tall, jagged ice spikes. Their research suggests Europa is an icy hedgehog world, covered in ice formations rarely found on Earth. On our planet, ice takes several forms, as varied as needle ice, rime, parking lot slush and more exotic lumps.
Patents

Walmart Patents Cart That Reads Your Pulse, Temperature (vice.com) 116

Walmart recently applied to patent biometric shopping handles that would track a shopper's heart rate, palm temperature, grip force, and walking speed. "The patent, titled 'System And Method For A Biometric Feedback Cart Handle' and published August 23, outlines a system where sensors in the cart send data to a server," reports Motherboard. "That server then notifies a store employee to check on individual customers." From the report: Over time, the server can build a database of data compared against store location and stress response, the patent says -- potentially valuable information for store planning. Other uses outlined in the patent include a pulse oximeter, for detecting when a customer's about to pass out, and a weight-triggered assisted push feature for propelling the cart itself. CBInsights suggests that these alerts could warn associates when several shoppers need help at the same time, or anticipate when arguments are about to break out.
Science

Physics Holds the Key To Performing the Flipping Water Bottle Trick (arstechnica.com) 56

An anonymous reader shares a report: Think of how ice skaters extend their arms and legs to slow down rotation coming out of jumps or spins. It's the same principle: conservation of angular momentum. Once the bottle is set in motion, its angular momentum remains constant. But shifting how the mass inside (the water) is distributed increases the bottle's rotational inertia (how much force is required to start or keep it moving). This slows down the bottle's rotational speed. Physicists from the University of Twente in the Netherlands decided to analyze the underlying physics [of flipping a half-full bottle of water so it lands upright] more thoroughly in a series of rigorous experiments and develop a theoretical model. For the first version of the experiment, they used a partially filled water bottle. For the second version, they reduced the variables from the large number of water molecules in the bottle to just two tennis balls in a cylindrical container. In both cases, their measurements clearly showed the dramatic decrease of the container's rotational speed, resulting in a nearly vertical descent, so the bottle landed neatly and upright. Tracking the sloshing of the liquid and the changing positions of the tennis balls demonstrated the redistribution of mass, shifting the moment of inertia.

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