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# Mathematicians calculate that there are 177,147 ways to knot a tie, far more than previously thought

A small team of mathematicians, led by Mikael Vejdemo-Johansson of the of the KTH Royal Institute of Technology in Stockholm, has uploaded a paper to the preprint server arXiv describing a mathematical process they used to determine that the number of ways to tie a tie is 177,147—far more than previous research has suggested.

Most men don't consider more than one, two or maybe three ways to tie their tie, if they tie one at all—but the fact is, there are far more ways to do it than most would ever imagine and because of that mathematicians have at times set themselves the task of trying to discern if the number is finite, and if so, what that number might be.

Back in 1999, a pair of researches (Yong Mao and Thomas Fink) with the University of Cambridge came up with a mathematical language to describe all the actions that can be performed in tying a tie and used it to calculate that the total number of possible outcomes was a very reasonable 85. In this new effort the researchers say that number is far too small because it leaves out some good possibilities. They've extended the mathematical language and have used it to create a new upper limit—177,147.

Vejdemo-Johansson apparently came to believe that the number produced by Mao and Fink was too small after noting the unique tie knot in the movie "The Matrix Reloaded"—a knot that didn't appear in the researchers list, which meant something wasn't quite right. In reexamining the criteria that Mao and Fink used for inclusion, they noted the pair restricted the number of tucks that would occur at the end of the tie tying, to just one. The pair, it was noted, also assumed that any knot created would naturally be covered in part by a flat section of fabric. Also, they restricted the number of windings that could be made to just eight, believing any more than that would cause the tie to become too short.

Vejdemo-Johansson adjusted the parameters and added nomenclature for describing tie movements and after putting it all together, used their new math language to calculate the new total number of possible tie knots—though, it might not be the last word—some of their parameter assignments, such as setting the maximum winds at 11, for example, could perhaps be adjusted for longer ties, or those made of much thinner material.

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## Astronomers detect dozens of new quasars and galaxies

A team of astronomers led by Yoshiki Matsuoka of the National Astronomical Observatory of Japan (NAOJ) has detected a treasure trove of new high-redshift quasars (or quasi-stellar objects) and luminous galaxies. The newly found objects could be very important for our understanding of the early universe. The findings were presented Apr. 19 in a paper published on arXiv.org.

High-redshift quasars and galaxies (at redshift higher than 5.0) are useful probes of the early universe in many respects. They offer essential clues on the evolution of the intergalactic medium, quasar evolution, early supermassive black hole growth, as well as evolution of galaxies through cosmic times. Generally speaking, they enable scientists to study the universe when it looked much different than it does today.

Recently, Matsuoka's team has presented the results from the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) project, which uses multi-band photometry data provided by the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP) survey. HSC is a wide-field camera installed on the Subaru 8.2 m telescope located at the summit of Maunakea, Hawaii and operated by NAOJ. The researchers selected nearly 50 photometric candidates from the HSC-SSP source catalog and then observed them with spectrographs on the Subaru Telescope and the Gran Telescopio Canarias (GTC), located on the island on the Canary Island of La Palma, Spain.

The observations resulted in the identification of 24 new quasars and eight new luminous galaxies at redshift between 5.7 and 6.8.

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## Breakthrough Listen Search for Intelligent Life: First Results from 1709 Stars

Breakthrough Listen — the largest ever research program aimed at finding evidence of intelligent life beyond Earth — has released its eleven events ranked highest for significance as well as summary data analysis results.

The Breakthrough Listen project, announced in 2015, is currently using the Green Bank Telescope in West Virginia, the Automated Planet Finder optical telescope at Lick Observatory and the Parkes Telescope in Australia, with plans to incorporate other large telescopes around the world. The Breakthrough Listen science team has so far acquired several petabytes of data — available at breakthroughinitiatives.org — using these telescopes.

The researchers designed and built an analysis pipeline that scans through billions of radio channels in a search for unique signals from extraterrestrial civilizations. “The basics of searching for signatures of extraterrestrial technology are quite simple,” the scientists explained.

“Artificial signals can be distinguished from natural processes through features like narrow bandwidth; irregular spectral behavior, pulsing, or modulation patterns; as well as broad-band signals with unusual characteristics.”

“However, human technology emits signals similar to the ones being searched for. This means that algorithms must be designed to ensure that signals are coming from a fixed point relative to the stars or other targets being observed, and not from local interferers.”

The initial results from deploying the pipeline on the first year of Breakthrough Listen data taken with the 100-m Green Bank Telescope have been submitted for publication in the Astrophysical Journal. “With the submission of this paper, the first scientific results from Breakthrough Listen are now available for the world to review,” said Dr. Andrew Siemion, an astrophysicist and Director of the Berkeley SETI Research Center.

“Although the search has not yet detected a convincing signal from extraterrestrial intelligence, these are early days.”

Dr. Siemion and co-authors examined data on 692 stars, consisting of three 5-min observations per star, interspersed with 5-min observations of a set of secondary targets.

The total number of Breakthrough Listen target stars, described by Isaacson et al in a recent paper in the Publications of the Astronomical Society of the Pacific (arXiv.org preprint), is 1709.

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## An Aurora Called 'Steve'? Strange Sky Phenomenon Investigated

Researchers collaborated with citizen scientists and astrophotographers to pinpoint a mysterious new aurora feature, nicknamed "Steve."

Photographer Dave Markel caught this view of a strange aurora-like feature that appears in the skies of northern Canada. Based on data from European Space Agency's Swarm satellites, it appears to be a 16-mile-wide (25 km) ribbon of flowing gas in an area whose temperature is 5,500 degrees Fahrenheit (3,000 degrees Celsius) higher than the surroundings; the gas flows at 3.5 miles per second (6 km/s) compared to a speed of 33 feet/second (10 m/s) on either side of the ribbon. They're calling the feature "Steve."

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## Exploring new frontiers of knowledge: AI invents knowledge and teaches human new theories

Google's DeepMind CEO Demis Hassabis shows that AI doesn't only learn from human knowledge, but also creates new knowledge. AlphaGo has it own creativity and intuition, inventing new knowledge and strategies about Go Game for human professionals to study in 2017.

Go game was invented in ancient China more than 2,500 years ago, is an abstract strategy board game, aiming to surround more territory than the opponent for two players. It is believed to be the oldest board game continuously played today.

Despite its relatively simple rules, Go is very complex, even more so than chess, and possesses more possibilities than the total number of atoms in the visible universe. Compared to chess, Go has both a larger board with more scope for play and longer games, and, on average, many more alternatives to consider per move.

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## For the first time, physicists have experimentally demonstrated the violation of "bilocal causality"

Physicists have recently been able to experimentally demonstrate the violation of "bilocal causality"—a concept that is related to the more standard local causality, except that it accounts for the precise way in which physical systems are initially generated. The results show that it's possible to violate local causality in an entirely new and more general way, which could lead to a potential new resource for quantum technologies.

The physicists, Gonzalo Carvacho et al., from institutions in Italy, Brazil, and Germany, have published a paper on the demonstration of the violation of bilocal causality in a recent issue of Nature Communications.

In general, the idea of local causality is usually taken for granted: objects can influence other objects only when they are physically close together, and any correlations between distant objects must have originated in the past when they were closer together. But in the quantum world, distant particles can be correlated in ways that are impossible for classical objects, unless these distant particles can somehow influence each other.

To determine whether local causality has been violated, physicists perform Bell tests, which attempt to violate Bell inequalities. If a Bell inequality is violated, then either locality or realism (or simply "local realism") has also been violated. There are dozens of different versions of Bell inequalities, but currently they all make the same assumption: that the correlations between particles all originate from a single common source. In real experiments, however, particles and their correlations can come from many different sources.

To address this issue, the new paper considers a new type of Bell inequality that accounts for the fact that the two sources of states used in the experiment are independent, the so-called bilocality assumption. By violating this new type of Bell inequality, the researchers have for the first time violated bilocal causality, indicating the presence of non-bilocal correlations that are completely different than other types of quantum correlations.

The researchers also showed that, in certain situations, it's possible to violate bilocal causality but not any other type of local causality. This finding further suggests that this type of violation is truly different than any standard local causality violation.

"Our work is an experimental proof-of-principle for network generalizations of Bell's theorem," coauthor Fabio Sciarrino at the Sapienza University of Rome told Phys.org.

"We experimentally demonstrated how bilocality can be considered a powerful resource enlarging our current capabilities to process information in a non-classical way."

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## New microscopy method breaks color barrier of optical imaging

Researchers at Columbia University have made a significant step toward breaking the so-called "color barrier" of light microscopy for biological systems, allowing for much more comprehensive, system-wide labeling and imaging of a greater number of biomolecules in living cells and tissues than is currently attainable. The advancement has the potential for many future applications, including helping to guide the development of therapies to treat and cure disease.

In a study published online April 19 in Nature, the team, led by Associate Professor of Chemistry Wei Min, reports the development of a new optical microscopy platform with drastically enhanced detection sensitivity. Additionally, the study details the creation of new molecules that, when paired with the new instrumentation, allow for the simultaneous labeling and imaging of up to 24 specific biomolecules, nearly five times the number of biomolecules that can be imaged at the same time with existing technologies.

"In the era of systems biology, how to simultaneously image a large number of molecular species inside cells with high sensitivity and specificity remains a grand challenge of optical microscopy," Min said. "What makes our work new and unique is that there are two synergistic pieces - instrumentation and molecules - working together to combat this long-standing obstacle. Our platform has the capacity to transform understanding of complex biological systems: the vast human cell map, metabolic pathways, the functions of various structures within the brain, the internal environment of tumors, and macromolecule assembly, to name just a few."

All existing methods of observing a variety of structures in living cells and tissues have their own strengths, but all are also hindered by fundamental limitations, not the least of which is the existence of a "color barrier."

Via Mariaschnee
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## What if you could type directly from your brain at 100 words per minute?

Regina Dugan, PhD, Facebook VP of Engineering, Building8, revealed on April 19, 2017 at the Facebook F8 conference 2017 a plan to develop a non-invasive brain-computer interface that will let you type at 100 wpm — by decoding neural activity devoted to speech. Dugan previously headed Google’s Advanced Technology and Projects Group, and before that, was Director of the Defense Advanced Research Projects Agency (DARPA).

She explained in a Facebook post that over the next two years, her team will be building systems that demonstrate “a non-invasive system that could one day become a speech prosthetic for people with communication disorders or a new means for input to augmented reality.”

Dugan said that “even something as simple as a ‘yes/no’ brain click … would be transformative.” That simple level has been achieved by using functional near-infrared spectroscopy (fNIRS) to measure changes in blood oxygen levels in the frontal lobes of the brain, as KurzweilAI recently reported. Near-infrared light can penetrate the skull and partially into the brain.

Dugan agrees that optical imaging is the best place to start, but her Building8 team team plans to go way beyond that research — sampling hundreds of times per second and precise to millimeters. The research team began working on the brain-typing project six months ago and she now has a team of more than 60 researchers who specialize in optical neural imaging systems that push the limits of spatial resolution and machine-learning methods for decoding speech and language.

The research is headed by Mark Chevillet, previously an adjunct professor of neuroscience at Johns Hopkins University. Besides replacing smartphones, the system would be a powerful speech prosthetic, she noted — allowing paralyzed patients to “speak” at normal speed.

Via LilyGiraud
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## Using CRISPR to reverse retinitis pigmentosa and restore visual function by turning rods to cones

Using the gene-editing tool CRISPR/Cas9, researchers at University of California San Diego School of Medicine and Shiley Eye Institute at UC San Diego Health, with colleagues in China, have reprogrammed mutated rod photoreceptors to become functioning cone photoreceptors, reversing cellular degeneration and restoring visual function in two mouse models of retinitis pigmentosa. The findings are published in the April 21 advance online issue of Cell Research.

Retinitis pigmentosa (RP) is a group of inherited vision disorders caused by numerous mutations in more than 60 genes. The mutations affect the eyes' photoreceptors, specialized cells in the retina that sense and convert light images into electrical signals sent to the brain. There are two types: rod cells that function for night vision and peripheral vision, and cone cells that provide central vision (visual acuity) and discern color. The human retina typically contains 120 million rod cells and 6 million cone cells.

In RP, which affects approximately 100,000 Americans and 1 in 4,000 persons worldwide, rod-specific genetic mutations cause rod photoreceptor cells to dysfunction and degenerate over time. Initial symptoms are loss of peripheral and night vision, followed by diminished visual acuity and color perception as cone cells also begin to fail and die. There is no treatment for RP. The eventual result may be legal blindness.

In their published research, a team led by senior author Kang Zhang, MD, PhD, chief of ophthalmic genetics, founding director of the Institute for Genomic Medicine and co-director of biomaterials and tissue engineering at the Institute of Engineering in Medicine, both at UC San Diego School of Medicine, used CRISPR/Cas9 to deactivate a master switch gene called Nrland a downstream transcription factor called Nr2e3.

CRISPR, which stands for Clustered Regularly Interspaced Short Palindromic Repeats, allows researchers to target specific stretches of genetic code and edit DNA at precise locations, modifying select gene functions. Deactivating either Nrl or Nr2e3 reprogrammed rod cells to become cone cells.

"Cone cells are less vulnerable to the genetic mutations that cause RP," said Zhang. "Our strategy was to use gene therapy to make the underlying mutations irrelevant, resulting in the preservation of tissue and vision."

The scientists tested their approach in two different mouse models of RP. In both cases, they found an abundance of reprogrammed cone cells and preserved cellular architecture in the retinas. Electroretinography testing of rod and cone receptors in live mice show improved function.

Via Mariaschnee
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## NASA Missions Suggest New Shape of Sun-Galaxy Interaction

New data from NASA’s Cassini mission, combined with measurements from the two Voyager spacecraft and NASA’s Interstellar Boundary Explorer, or IBEX, suggests that our sun and planets are surrounded by a giant, rounded system of magnetic field from the sun — calling into question the alternate view of the solar magnetic fields trailing behind the sun in the shape of a long comet tail.

The sun releases a constant outflow of magnetic solar material — called the solar wind — that fills the inner solar system, reaching far past the orbit of Neptune. This solar wind creates a bubble, some 23 billion miles across, called the heliosphere. Our entire solar system, including the heliosphere, moves through interstellar space.

The prevalent picture of the heliosphere was one of comet-shaped structure, with a rounded head and an extended tail. But new data covering an entire 11-year solar activity cycle show that may not be the case: the heliosphere may be rounded on both ends, making its shape almost spherical. A paper on these results was published in Nature Astronomy on April 24, 2017.

“Instead of a prolonged, comet-like tail, this rough bubble-shape of the heliosphere is due to the strong interstellar magnetic field — much stronger than what was anticipated in the past — combined with the fact that the ratio between particle pressure and magnetic pressure inside the heliosheath is high,” said Kostas Dialynas, a space scientist at the Academy of Athens in Greece and lead author on the study.

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## Scientists identify a black hole choking on stardust

In the center of a distant galaxy, almost 300 million light years from Earth, scientists have discovered a supermassive black hole that is “choking” on a sudden influx of stellar debris.

In a paper published today in Astrophysical Journal Letters, researchers from MIT, NASA’s Goddard Space Flight Center, and elsewhere report on a “tidal disruption flare” — a dramatic burst of electromagnetic activity that occurs when a black hole obliterates a nearby star. The flare was first discovered on Nov. 11, 2014, and scientists have since trained a variety of telescopes on the event to learn more about how black holes grow and evolve.

The MIT-led team looked through data collected by two different telescopes and identified a curious pattern in the energy emitted by the flare: As the obliterated star’s dust fell into the black hole, the researchers observed small fluctuations in the optical and ultraviolet (UV) bands of the electromagnetic spectrum. This very same pattern repeated itself 32 days later, this time in the X-ray band.

The researchers used simulations of the event performed by others to infer that such energy “echoes” were produced from the following scenario: As a star migrated close to the black hole, it was quickly ripped apart by the black hole’s gravitational energy. The resulting stellar debris, swirling ever closer to the black hole, collided with itself, giving off bursts of optical and UV light at the collision sites. As it was pulled further in, the colliding debris heated up, producing X-ray flares, in the same pattern as the optical bursts, just before the debris fell into the black hole.

“In essence, this black hole has not had much to feed on for a while, and suddenly along comes an unlucky star full of matter,” says Dheeraj Pasham, the paper’s first author and a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research. “What we’re seeing is, this stellar material is not just continuously being fed onto the black hole, but it’s interacting with itself — stopping and going, stopping and going. This is telling us that the black hole is ‘choking’ on this sudden supply of stellar debris.”

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## Atomic-level motion may drive bacteria's ability to evade immune system defenses

A study from Indiana University has found evidence that extremely small changes in how atoms move in bacterial proteins can play a big role in how these microorganisms function and evolve.

The research, recently published in theProceedings of the National Academy of Sciences, is a major departure from prevailing views about the evolution of new functions in organisms, which regarded a protein's shape, or "structure," as the most important factor in controlling its activity.

"This study gives us a significant answer to the following question: How do different organisms evolve different functions with proteins whose structures all look essentially the same?" said David Giedroc, Lilly Chemistry Alumni Professor in the IU Bloomington College of Arts and Sciences' Department of Chemistry, who is senior author on the study. "We've found evidence that atomic motions in proteins play a major role in impacting their function."

The study also provides new insights into how microorganisms respond to their host's efforts to limit bacterial infection. Serious bacterial infections in people include severe health-care-associated infections and tuberculosis, both of which have grown increasingly common over the past decade due to rising drug resistance in bacteria. About 480,000 people worldwide develop multidrug-resistant tuberculosis each year, for example, according to the Centers for Disease Control and Prevention.

"What we've shown is atomic-level motional disorder -- or entropy -- can impact gene transcription to affect the function of proteins in major ways, and that these motions can be 'tuned' evolutionarily," said Daiana A. Capdevila, a postdoctoral researcher in Giedroc's lab, who is first author on the study. "This may allow bacteria to rapidly evolve new ways to overcome medical treatment since atomic motions can be optimized for function more easily than a physical structure."

In the battle between bacterial infection and modern medicine, she said a key step is "mapping" the enemy's territory. Unraveling the molecular structure of proteins that trigger the mechanisms that thwart the human immune system informs the design of new drugs. However, this approach is based on the assumption that a protein's shape fundamentally controls its behavior.

It also assumes proteins are rigid. The new study shows protein function is better understood by studying the structure's internal atomic motion.

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## Quantum dots that emit infrared light open new window for biological imaging

For certain frequencies of short-wave infrared light, most biological tissues are nearly as transparent as glass. Now, researchers have made tiny particles that can be injected into the body, where they emit those penetrating frequencies. The advance may provide a new way of making detailed images of internal body structures such as fine networks of blood vessels.

The key was to develop versions of these quantum dots whose emissions matched the desired short-wave infrared frequencies and were bright enough to then be easily detected through the surrounding skin and muscle tissues. The team succeeded in making particles that are "orders of magnitude better than previous materials, and that allow unprecedented detail in biological imaging," Bruns says. The synthesis of these new particles was initially described in a paper by graduate student Daniel Franke and others from the Bawendi group in Nature Communications last year.

The new findings, based on the use of light-emitting particles called quantum dots, is described in a paper in the journal Nature Biomedical Engineering, by MIT research scientist Oliver Bruns, recent graduate Thomas Bischof PhD '15, professor of chemistry Moungi Bawendi, and 21 others.

Near-infrared imaging for research on biological tissues, with wavelengths between 700 and 900 nanometers (billionths of a meter), is widely used, but wavelengths of around 1,000 to 2,000 nanometers have the potential to provide even better results, because body tissues are more transparent to that light. "We knew that this imaging mode would be better" than existing methods, Bruns explains, "but we were lacking high-quality emitters"—that is, light-emitting materials that could produce these precise wavelengths.

Light-emitting particles have been a specialty of Bawendi, the Lester Wolf Professor of Chemistry, whose lab has over the years developed new ways of making quantum dots. These nanocrystals, made of semiconductor materials, emit light whose frequency can be precisely tuned by controlling the exact size and composition of the particles.

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## Lyrebird — an API for generating human voice

Lyrebird is the first company to offer a technology to reproduce the voice of someone as accurately and with as little recorded audio. Such a technology raises important societal issues that we address in the next paragraphs.

Voice recordings are currently considered as strong pieces of evidence in our societies and in particular in jurisdictions of many countries. Our technology questions the validity of such evidence as it allows to easily manipulate audio recordings. This could potentially have dangerous consequences such as misleading diplomats, fraud and more generally any other problem caused by stealing the identity of someone else.

By releasing our technology publicly and making it available to anyone, we want to ensure that there will be no such risks. We hope that everyone will soon be aware that such technology exists and that copying the voice of someone else is possible. More generally, we want to raise attention about the lack of evidence that audio recordings may represent in the near future.

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## The arrhythmic beating of a black hole heart – Astronomy Now

At the center of the Centaurus galaxy cluster, there is a large elliptical galaxy called NGC 4696. Deeper still, there is a supermassive black hole buried within the core of this galaxy.

New data from NASA’s Chandra X-ray Observatory and other telescopes has revealed details about this giant black hole, located some 145 million light years from Earth. Although the black hole itself is undetected, astronomers are learning about the impact it has on the galaxy it inhabits and the larger cluster around it.

In some ways, this black hole resembles a beating heart that pumps blood outward into the body via the arteries. Likewise, a black hole can inject material and energy into its host galaxy and beyond.

By examining the details of the X-ray data from Chandra, scientists have found evidence for repeated bursts of energetic particles in jets generated by the supermassive black hole at the center of NGC 4696. These bursts create vast cavities in the hot gas that fills the space between the galaxies in the cluster. The bursts also create shock waves, akin to sonic booms produced by high-speed airplanes, which travel tens of thousands of light years across the cluster.

The composite image shown contains X-ray data from Chandra (red) that reveals the hot gas in the cluster, and radio data from the NSF’s Karl G. Jansky Very Large Array (blue) that shows high-energy particles produced by the black hole-powered jets. Visible light data from the Hubble Space Telescope (green) show galaxies in the cluster as well as galaxies and stars outside the cluster.

Astronomers employed special processing to the X-ray data to emphasize nine cavities visible in the hot gas. These cavities are labeled A through I in an additional image, and the location of the black hole is labeled with a cross. The cavities that formed most recently are located nearest to the black hole, in particular the ones labeled A and B.

The researchers estimate that these black hole bursts, or “beats”, have occurred every five to ten million years. Besides the vastly differing time scales, these beats also differ from typical human heartbeats in not occurring at particularly regular intervals.

A different type of processing of the X-ray data reveals a sequence of curved and approximately equally spaced features in the hot gas. These may be caused by sound waves generated by the black hole’s repeated bursts. In a galaxy cluster, the hot gas that fills the cluster enables sound waves – albeit at frequencies far too low for the human hear to detect – to propagate.

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## Hubble Spots Multiply-Imaged, Gravitationally Lensed Type Ia Supernova | Astronomy

Type Ia supernovae always have the same intrinsic brightness, so by measuring how bright they appear astronomers can determine how far away they are.

Known as standard candles, these supernovae have been used for decades to measure distances across the Universe, and were also used to discover its accelerated expansion and infer the existence of dark energy.

“Resolving, for the first time, multiple images of a strongly lensed standard candle supernova is a major breakthrough,” said Prof. Ariel Goobar, from the Oskar Klein Centre at Stockholm University in Sweden.

“We can measure the light-focusing power of gravity more accurately than ever before, and probe physical scales that may have seemed out of reach until now.”

The newly-discovered supernova, called iPTF16geu, was first detected on September 5, 2016 by the intermediate Palomar Transient Factory (iPTF) collaboration with the Palomar Observatory.

Also known as SN 2016geu, the supernova exploded at a distance corresponding to a time 4.3 billion years ago. It could only be detected because a foreground galaxy — SDSS J210415.89-062024.7, which is 2.5 billion light-years away — lensed the light of the explosion, making it 52 times brighter for observers on Earth.

It also caused iPTF16geu to appear in four distinct places on the sky, surrounding the lensing galaxy in the foreground. The four images lie on a circle with a radius of only 3,000 light-years around the galaxy, making it one of the smallest extragalactic gravitational lenses discovered so far.

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## The final chapter in a remarkable mission of exploration and discovery: Cassini's Grand Finale

Cassini is one of the most ambitious efforts in planetary space exploration. A joint endeavour of NASA, ESA and the Italian space agency, Cassini is a sophisticated spacecraft exploring the Saturnian system since 2004.

The final chapter in a remarkable mission of exploration and discovery, Cassini's Grand Finale is in many ways like a brand new mission. Twenty-two times, NASA's Cassini spacecraft will dive through the unexplored space between Saturn and its rings. What we learn from these ultra-close passes over the planet could be some of the most exciting revelations ever returned by the long-lived spacecraft. This animated video tells the story of Cassini's final, daring assignment and looks back at what the mission has accomplished.

For more about the making of this video, including the science behind the imagery, see the feature at https://saturn.jpl.nasa.gov

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## Naked mole-rats turn to fructose-driven metabolism when oxygen is low

Deprived of oxygen, naked mole-rats can survive by metabolizing fructose just as plants do, researchers report this week in the journal Science. Understanding how the animals do this could lead to treatments for patients suffering crises of oxygen deprivation, as in heart attacks and strokes.

“This is just the latest remarkable discovery about the naked mole-rat — a cold-blooded mammal that lives decades longer than other rodents, rarely gets cancer, and doesn’t feel many types of pain,” says Thomas Park, professor of biological sciences at the University of Illinois at Chicago, who led an international team of researchers from UIC, the Max Delbrück Institute in Berlin and the University of Pretoria in South Africa on the study.Ignore the whiskers and teeth — these are plants.

In humans, laboratory mice, and all other known mammals, when brain cells are starved of oxygen they run out of energy and begin to die. But naked mole-rats have a backup: their brain cells start burning fructose, which produces energy anaerobically through a metabolic pathway that is only used by plants – or so scientists thought.

In the new study, the researchers exposed naked mole-rats to low oxygen conditions in the laboratory and found that they released large amounts of fructose into the bloodstream. The fructose, the scientists found, was transported into brain cells by molecular fructose pumps that in all other mammals are found only on cells of the intestine.

“The naked mole-rat has simply rearranged some basic building-blocks of metabolism to make it super-tolerant to low oxygen conditions,” said Park, who has studied the strange species for 18 years. At oxygen levels low enough to kill a human within minutes, naked mole-rats can survive for at least five hours, Park said. They go into a state of suspended animation, reducing their movement and dramatically slowing their pulse and breathing rate to conserve energy. And they begin using fructose until oxygen is available again. The naked mole-rat is the only known mammal to use suspended animation to survive oxygen deprivation.

The scientists also showed that naked mole-rats are protected from another deadly aspect of low oxygen – a buildup of fluid in the lungs called pulmonary edema that afflicts mountain climbers at high altitude. The scientists think that the naked mole-rats’ unusual metabolism is an adaptation for living in their oxygen-poor burrows. Unlike other subterranean mammals, naked mole-rats live in hyper-crowded conditions, packed in with hundreds of colony mates. With so many animals living together in unventilated tunnels, oxygen supplies are quickly depleted.

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## How to stay organized: DNA's secret weapon against knots and tangles

A simple process seems to explain how massive genomes stay organized. But no one can agree on what powers it.

Leonid Mirny swivels in his office chair and grabs the power cord for his laptop. He practically bounces in his seat as he threads the cable through his fingers, creating a doughnut-sized loop. “It's a dynamic process of motors constantly extruding loops!” says Mirny, a biophysicist here at the Massachusetts Institute of Technology in Cambridge.

Mirny's excitement isn't about keeping computer accessories orderly. Rather, he's talking about a central organizing principle of the genome — how roughly 2 metres of DNA can be squeezed into nearly every cell of the human body without getting tangled up like last year's Christmas lights.

He argues that DNA is constantly being slipped through ring-like motor proteins to make loops. This process, called loop extrusion, helps to keep local regions of DNA together, disentangling them from other parts of the genome and even giving shape and structure to the chromosomes.

Scientists have bandied about similar hypotheses for decades, but Mirny's model, and a similar one championed by Erez Lieberman Aiden, a geneticist at Baylor College of Medicine in Houston, Texas, add a new level of molecular detail at a time of explosive growth for research into the 3D structure of the genome. The models neatly explain the data flowing from high-profile projects on how different parts of the genome interact physically — which is why they've garnered so much attention.

But these simple explanations are not without controversy. Although it has become increasingly clear that genome looping regulates gene expression, possibly contributing to cell development and diseases such as cancer, the predictions of the models go beyond what anyone has ever seen experimentally.

For one thing, the identity of the molecular machine that forms the loops remains a mystery. If the leading protein candidate acted like a motor, as Mirny proposes, it would guzzle energy faster than it has ever been seen to do. “As a physicist friend of mine tells me, 'This is kind of the Higgs boson of your field',” says Mirny; it explains one of the deepest mysteries of genome biology, but could take years to prove.

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## AI is the only option in the future of cyber security

The cyber security wars of the future will be fought by good AI bots and bad ones, with the rest of us just watching to see who wins. That’s the future according to Jason Hoffman, Ericsson’s VP of Cloud Infrastructure. It isn’t quite as dark as the world being taking over by robots or sentient beings, but it’s a very realistic possibility due to the vast complications and workloads which will soon be placed on security teams.

“Ironically and unfortunately, some of the people who are becoming most advanced when it comes to artificial intelligence in the security world are the ones on the offensive,” said Hoffman. “These are the cyber criminals, and one of the only ways to combat these guys will be to escalate defences to be built around artificial intelligence.”

It’s a world which pits computer against computer, where Darwinism has taken a twist. The definition of ‘fittest’ moves away from strength and into the sphere of the intellectuals. But this is the end of the story, not the beginning.

At the beginning, where we are right now, there is a shift in the security paradigm. In the first instance, its due to the way infrastructure is purchased and managed. In years gone, buying and securing infrastructure was relatively simple. You bought the hardware and set up restrictions surrounding the software do define who could access sensitive areas. The introduction of cloud-computing has increased accessibility, and therefore the way in which we make our life secure.

One of the most attractive principles of cloud computing is the ease to scale and consume. On the operational side, this is a game changer, but for security it becomes a much more complicated task. The security paradigm has been permanently altered, as more people are now able to access sensitive areas of the machine.

If one objective is to remove the threat of malicious insiders, the task has become more complex, as the ease of consumption has multiplied the number of potential malicious insiders vastly. Restrictions have to be opened up to create the cloud business model and move towards a DevOps mindset, but this involves a much more comprehensive security and governance model to be put in place, which most organizations do not currently have.

Another complication is the means the shift in how infrastructure is managed. Previously, hardware has been bought, it is secured in the warehouse and then shipped to the customer. It was secure until it had served its purpose and ultimately replaced. Hoffman highlighted that a continuous stream of software updates now mean the system is only as secure as it was the last time you checked. Every update is a potential weak link in the perimeter, which again, organizations are not prepared for. It involves a complete rethink of how supply chain assurance is managed.

In both these instances, the data which needs to be managed to ensure security is far too vast for any human to consider. From Hoffman’s perspective, the only option is a machine learning algorithm, which understands what would be considered normal performance from each component, and constantly monitors for the anomalies. Here, artificial intelligence is aiding the security professionals by finding the leak and then alerting, but it won’t be long before AI is the leading player.

Via Ben van Lier
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## Blockchain is making it easy for neighbors to sell each other excess solar energy over P2P

If you have solar panels that produce more energy than you need, you can sell the excess to a utility company. But what if you could sell it to your neighbor instead?

A company called LO3 Energy has developed a system that lets people buy and sell locally generated solar energy within their communities. The system uses blockchain—the electronic ledger technology that underpins the digital currency Bitcoin—to facilitate and record the transactions.

Distributing energy this way is more efficient than transmitting energy over distances, said LO3’s founder, Lawrence Orsini, and would make neighborhoods more resilient to power outages, as well as helping meet demand when energy needs exceed expectations. It’s also in line with growing public support for renewable energy, distributed and decentralized energy systems, and “buy local” programs in general.

At Business of Blockchain, a conference organized by MIT Technology Review and the MIT Media Lab, Orsini said that 69 percent of consumers told the technology consultancy Accenture that they were interested in having an energy-trading marketplace, and 47 percent said they planned to sign up for community solar projects.

LO3 Energy launched its peer-to-peer energy transactions system, which it calls the Brooklyn Microgrid, about a year ago. The miniature utility grid connects people who have solar panels on their roofs in several parts of Brooklyn with neighbors who want to buy locally generated green energy. Like other microgrids it operates alongside, but separate from, the traditional energy grid.

Blockchain makes the Brooklyn Microgrid possible, Orsini said. Participants install smart meters equipped with the technology, which track the energy they generate and consume. Records of the automatic “smart contracts” that enable neighbor-to-neighbor transactions are also tracked using blockchain. LO3 Energy hired the software maker ConsenSys to build the system, which is based on the blockchain-based distributed computing platform Ethereum.

“Blockchain is a really good communications protocol for what we want to do,” Orsini said at the conference. “This isn’t just about settling energy bills,” he added. “It’s about self-organizing at the grid edge, which can’t be done with normal databases.”

Could microgrids like this shake up the energy industry? At the moment, Brooklyn Microgrid consists of only 50 physical nodes, but Orsini signed a partnership with German conglomerate Siemens in November and is talking to regulators in the U.S., Australia, and Europe about expansion. He is also willing to collaborate with utilities. “We’re not putting the utilities out of business, but we want their business model to evolve,” he said.

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## Young human blood makes old mice smarter

Mice treated with a protein from umbilical cord plasma improved their performance on memory tests.

Infusing human plasma into the veins of elderly mice, researchers found, improved the animals’ ability to navigate mazes and to learn to avoid areas of their cages that deliver painful electrical shocks. When the researchers dissected the animals’ brains, they found that cells in the hippocampus — the region associated with learning and memory — expressed genes that caused neurons to form more connections in the brain. This didn't happen in mice treated with blood from older human donors.

The scientists then compared a slate of 66 proteins found in umbilical cord plasma to the proteins in plasma from older people, and to proteins identified in the mouse parabiosis experiments. They found several potential candidates, and injected them, one at a time, into the veins of old mice. The team then ran the animals through the memory experiments.

Only one of these proteins, TIMP2, improved the animals’ performance. It did not, however, result in regeneration of brain cells that are lost during normal aging. Injections of human umbilical cord plasma lacking TIMP2 had no effect on memory.

The researchers don’t yet know how TIMP2, which is known to be involved in maintaining cell and tissue structure, exerts its effect on memory. And although it is expressed in the brains of young mice, TIMP2 has never before been linked to learning or memory. Some scientists suspects that the protein functions as a 'master regulator' of genes involved in the growth of cells and blood vessels, and that increasing its levels affects many pathways simultaneously.

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## Teaching robots right from wrong

Robots of the future will face tricky dilemmas. Researchers are working on tools to help robots make the right choices and keep people safe.

You’re rushing across the school parking lot to get to your first class on time when you notice a friend is in trouble. She’s texting and listening to music on her headphones. Unawares, she’s also heading straight for a gaping hole in the sidewalk. What do you do? The answer seems pretty simple: Run over and try to stop her before she hurts herself. Who cares if you might be a little late for class?

To figure out the best solution, such a decision balances the effects of your choice. It’s an easy decision. You don’t even have to think hard about it. You make such choices all the time. But what about robots? Can they make such choices? Should a robot stop your friend from falling into the hole? Could it?

Not today’s robots. They simply aren’t smart enough to even realize when someone is in danger. Soon, they might be. Yet without some rules to follow, a robot wouldn’t know the best choice to make.

So robot developers are turning to philosophy. Called ethics, it’s a field in which people study differences between right and wrong. And with it, they are starting to develop robots that can make basic ethical decisions.

One lab’s robot is mastering the hole scenario. Another can decide not to follow a human’s instructions if they seem unsafe. A third robot is learning how to handle tricky situations in a nursing home. Such research should help robots of the future figure out the best action to take when there are competing choices. This ethical behavior may just become part of their programming. That will allow them to interact with people in safe, predictable ways. In time, robots may actually begin to understand the difference between right and wrong.

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## Totally bizarre facts about the star-nosed mole

In a new synthesis of anatomy research, scientists showcase the surprising, record-breaking and just plain weird adaptations of the star-nosed mole. The animal eats faster and sports a more sensitive touch organ than any other mammal, is the first mammal known to smell underwater and offers fascinating insights about the brain-body interface.

A quarter-century of research on the star-nosed mole has unearthed startling insights into the evolution of animal behavior and the limits of physiology. Kenneth Catania of Vanderbilt University will present a new synthesis of remarkable anatomical findings about the star-nosed mole at the American Association of Anatomists annual meeting during the Experimental Biology 2017 meeting, to be held April 22-26 in Chicago.

"Star-nosed moles are truly amazing animals," said Catania, a neuroscientist who's interest in the creature was first piqued while working as an undergraduate research assistant at the National Zoo in Washington, D.C. "Obviously they are among the weirdest looking creatures on the planet. But when I began trying to understand the star, the mole's brain organization, and its behavior--that's when things got really surprising." Here are some highlights:

They eat faster than any other mammal on Earth.

Star-nosed moles can identify and eat food (bugs, mostly) in less than two-tenths of a second, taking a mere 8 milliseconds to decide whether an item is edible or not. They perform this feat in part due to the extremely efficient operation of their nervous systems, which convey information from the environment to the animal's brain at speeds approaching the physiological limit of neurons.

Their star is the most sensitive known touch organ in any mammal.

The distinctive star organ on the mole's snout contains more than 100,000 nerve fibers--five times the number of "touch" fibers in the human hand, all packed into a space smaller than your fingertip. "The star skin is so sensitive that we have not been able to determine the lowest threshold for activating neurons," said Catania, adding that studying the star could provide insights that improve our understanding of the human sense of touch.

Their sense of touch mirrors our sense of sight.

At the center of the star organ is a small area called the touch fovea that the mole uses for all of its most detailed explorations. Although the mole's actual eyes are essentially useless, the touch fovea is neurologically organized in a way that is strikingly similar to the organization of a highly developed visual system. As the mole moves through its environment, it constantly shifts the star to reposition the fovea on areas of interest, just as we shift our eyes while reading the words printed on a page, for example. "These parallels suggest there are common strategies by which evolution 'builds' high-resolution sensory systems, whether they are based on sight or on touch," Catania said.

If you use the right dye, you can literally see which parts of their brains map to which body parts.

Scientists create maps of the brains of humans and other animals using a painstaking process of trial and error to determine which areas of the brain control (and receive stimuli from) various parts of the body. In star-nosed moles, you can actually see the brain maps with the right kinds of cellular stains. "You can basically see a 'star' in the mole's neocortex," said Catania. "That allows us to make all kinds of detailed measurements and neural recordings that are very difficult in other species."

Also, they can smell underwater. And their front legs are shovels.

Star-nosed moles are like a poster child for extreme evolutionary adaptations. Using their shovel-like front limbs to tunnel through soggy, marsh-like areas, the moles often dive and swim for food. Star-nosed moles have been shown to blow bubbles into the water and then re-inhale them through the nose in order to sniff for prey, making them the first mammal known to smell underwater.

Star-nosed moles are not uncommon, just uncommonly seen, said Catania. The species' range stretches along the Eastern portions of the U.S. and Canada. So keep an eye out--what you find just might surprise you.

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## Frog Skin Peptide Could Prevent the Next Influenza Pandemic

New research from Emory University School of Medicine shows that a chemical in the mucus of South Indian frogs is capable of killing certain strains of the influenza virus. It’ll take a while for scientists to translate this finding into a useful medicine, but the discovery could lead to an entirely new source of powerful anti-viral drugs.

Skin slime from the South Indian frog Hydrophylax bahuvistara contains a compound that kills bacteria and viruses, according to a study published today in the journal Immunity. In tests on mice, a synthesized version of the molecule was successful at killing a variety of influenza viruses, namely the H1 pandemic strains that make the rounds each year. Eventually, a drug inspired by this compound could be used to attack an emerging H1 strain, or it could be used when vaccines are unavailable.

Unfortunately, this compound, dubbed “urumin,” doesn’t last very long in the body, so scientists are now trying to figure out how to make it more stable. That said, the discovery shows that amphibians, and possibly other animals, are a potential new source of disease-fighting compounds. The researchers who led the study are hopeful that similar frog-derived molecules can be used against other viruses, such as dengue and Zika.

Frogs can’t catch the flu, but they’re susceptible to bacterial infections and other diseases. Consequently, the Emory scientists had good reason to suspect that certain peptides produced by frogs—peptides are short chains of amino acids that form the building blocks of proteins—packed an anti-viral punch. The peptide attaches itself to the virus and literally dismantles it.

“Peptides derived from the skin of frogs have antibacterial activity. We hypothesized some peptides might also have antiviral activity and hence we tested them against flu viruses,” said lead researcher Joshy Jacob in an interview with Gizmodo. “The frogs secrete this peptide almost certainly to combat some pathogen in [their] niche. The flu virus most likely shares a common motif with whatever the peptide is targeted to.”

Indeed, the peptide seems to be pretty good at attacking influenza. It attaches itself to hemagglutinin, the major protein on the surface of influenza virus, resulting in the dismantling and eventual death of the virus.
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## Time crystals may hold the key to developing quantum computers

Harvard physicists have created a new form of matter - dubbed a time crystal - which could offer important insights into the mysterious behavior of quantum systems.

Traditionally speaking, crystals - like salt, sugar or even diamonds - are simply periodic arrangements of atoms in a three-dimensional lattice.

Time crystals, on the other hand, take that notion of periodically-arranged atoms and add a fourth dimension, suggesting that - under certain conditions - the atoms that some materials can exhibit periodic structure across time.

Led by Professors of Physics Mikhail Lukin and Eugene Demler, a team consisting of post-doctoral fellows Renate Landig and Georg Kucsko, Junior Fellow Vedika Khemani, and Physics Department graduate students Soonwon Choi, Joonhee Choi and Hengyun Zhou built a quantum system using a small piece of diamond embedded with millions of atomic-scale impurities known as nitrogen-vacancy (NV) centers. They then used microwave pulses to "kick" the system out of equilibrium, causing the NV center's spins to flip at precisely-timed intervals - one of the key markers of a time crystal. The work is described in a paper published in Nature in March.

But the creation of a time crystal isn't significant merely because it proves the previously-only-theoretical materials can exist, Lukin said, but because they offer physicists a tantalizing window into the behavior of such out-of-equilibrium systems.

"There is now broad, ongoing work to understand the physics of non-equilibrium quantum systems," Lukin said. "This is an area that is of interest for many quantum technologies, because a quantum computer is basically a quantum system that's far away from equilibrium. It's very much at the frontier of research...and we are really just scratching the surface."

But while understanding such non-equlibrium systems could help lead researchers down the path to quantum computing, the technology behind time crystals may also have more near-term applications as well.

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