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Some 290 million years ago, a star much like the sun wandered too close to the central black hole of its galaxy. Intense tides tore the star apart, which produced an eruption of optical, ultraviolet and X-ray light that first reached Earth in 2014.
Now, a team of scientists using observations from NASA's Swift satellite have mapped out how and where these different wavelengths were produced in the event, named ASASSN-14li, as the shattered star's debris circled the black hole.
"We discovered brightness changes in X-rays that occurred about a month after similar changes were observed in visible and UV light," said Dheeraj Pasham, an astrophysicist at the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts, and the lead researcher of the study. "We think this means the optical and UV emission arose far from the black hole, where elliptical streams of orbiting matter crashed into each other."
Astronomers think ASASSN-14li was produced when a sun-like star wandered too close to a 3-million-solar-mass black hole similar to the one at the center of our own galaxy. For comparison, the event horizon of a black hole like this is about 13 times bigger than the sun, and the accretion disk formed by the disrupted star could extend to more than twice Earth's distance from the sun.
When a star passes too close to a black hole with 10,000 or more times the sun's mass, tidal forces outstrip the star's own gravity, converting the star into a stream of debris. Astronomers call this a tidal disruption event. Matter falling toward a black hole collects into a spinning accretion disk, where it becomes compressed and heated before eventually spilling over the black hole's event horizon, the point beyond which nothing can escape and astronomers cannot observe. Tidal disruption flares carry important information about how this debris initially settles into an accretion disk.
Doctors have stumbled on an unlikely source for a drug to ward off brain damage caused by strokes: the venom of one of the deadliest spiders in the world.
A bite from an Australian funnel web spider can kill a human in 15 minutes, but a harmless ingredient found in the venom can protect brain cells from being destroyed by a stroke, even when given hours after the event, scientists say. If the compound fares well in human trials, it could become the first drug that doctors have to protect against the devastating loss of neurons that strokes can cause.
Researchers discovered the protective molecule by chance as they sequenced the DNA of toxins in the venom of the Darling Downs funnel web spider (Hadronyche infensa) that lives in Queensland and New South Wales. Venom from three spiders was gathered for the study after scientists trapped and “milked exhaustively” three spiders on Orchid beach, about 400km north of Brisbane.
The molecule, called Hi1a, stood out because it looked like two copies of another brain cell-protecting chemical stitched together. It was so intriguing that scientists decided to synthesize the compound and test its powers. “It proved to be even more potent,” said Glenn King at the University of Queensland’s centre for pain research.
Strokes occur when blood flow to the brain is interrupted and the brain is starved of oxygen. About 85% of strokes are caused by blockages in blood vessels in the brain, with the rest due to bleeds when vessels rupture. Approximately six million people a year die from stroke, making it the second largest cause of death worldwide after heart attacks.
If you’re overweight and find it challenging to exercise regularly, now there’s good news: A less strenuous form of exercise known as whole-body vibration (WBV) can mimic the muscle and bone health benefits of regular exercise — at least in mice — according to a new study published in the Endocrine Society’s journal Endocrinology.
Lack of exercise is contributing to the obesity and diabetes epidemics, according to the researchers. These disorders can also increase the risk of bone fractures. Physical activity can help to decrease this risk and reduce the negative metabolic effects of these conditions.
But the alternative, WBV, can be experienced while sitting, standing, or even lying down on a machine with a vibrating platform. When the machine vibrates, it transmits energy to your body, and your muscles contract and relax multiple times during each second.
“Our study is the first to show that whole-body vibration may be just as effective as exercise at combating some of the negative consequences of obesity and diabetes,” said the study’s first author, Meghan E. McGee-Lawrence, Ph.D., ofAugusta University in Georgia. “While WBV did not fully address the defects in bone mass of the obese mice in our study, it did increase global bone formation, suggesting longer-term treatments could hold promise for preventing bone loss as well.”
Just as effective as a treadmill
Glucose and insulin tolerance testing revealed that the genetically obese and diabetic mice showed similar metabolic benefits from both WBV and exercising on a treadmill. Obese mice gained less weight after exercise or WBV than obese mice in the sedentary group, although they remained heavier than normal mice. Exercise and WBV also enhanced muscle mass and insulin sensitivity in the genetically obese mice.
The findings suggest that WBV may be a useful supplemental therapy to combat metabolic dysfunction in individuals with morbid obesity. “These results are encouraging,” McGee-Lawrence said. “However, because our study was conducted in mice, this idea needs to be rigorously tested in humans to see if the results would be applicable to people.”
The authors included researchers at the National Institute of Health’s National Institute of Aging (NIA). Funding was provided by the American Diabetes Association, the National Institutes of Health’s National Institute of Diabetes and Digestive Kidney Diseases, and the National Institute on Aging.
If you should one day find yourself in a spacecraft circling Mars, don’t count on a good view. The Red Planet’s dusty atmosphere will probably obscure any window-seat vistas of its deep valleys and soaring mesas. “The best way to see the planet’s surface would be to take a digital image and enhance it on your computer,” says planetary geologist Alfred McEwen, principle investigator on NASA’s High Resolution Imaging Science Experiment.
He would know: In the past 12 years, the powerful HiRISE camera has snapped 50,000 spectacular, high-resolution stereo images of the Martian terrain from the planet’s orbit, creating anaglyphs that anyone can view in 3D using special glasses. The highly detailed stereograms depict the planet’s surface in remarkable detail—but 3D glasses aren’t always handy, and still images can only convey so much about Mars’ varied topography.
To fully appreciate the Martian landscape, one needs dimension and movement. In the video you see here, Finnish filmmaker Jan Fröjdman transformed HiRISE imagery into a dynamic, three-dimensional, overhead view of the Red Planet—no glasses required. For Fröjdman, creating the flyover effect was like assembling a puzzle. He began by colorizing the photographs (HiRISE captures images in grayscale). He then identified distinctive features in each of the anaglyphs—craters, canyons, mountains–and matched them between image pairs. To create the panning 3-D effect, he stitched the images together along his reference points and rendered them as frames in a video. “It was a very slow process,” he says.
Researchers at the Tokyo Institute of Technology and Nippon Telegraph and Telephone Corporation have developed a "spin-resolved oscilloscope." This device is a basic measuring instrument for plasmonics and spintronics, which are key technologies for future electronics applications. The coupling of light and electronic charges in plasmonics will pave the way for ultra-high-speed information processing, whereas spintronics will provide low-energy-consumption technology in a highly information-oriented society. The spin-resolved oscilloscope pioneers future "spin-plasmonics," where ultra-high-speed low-energy-consumption devices will be achieved.
An electron has charge and spin, and both the charge- and spin-density excitations in an electronic system can be utilized in information processing. The dynamics of charge-density waves has been investigated in plasmonics, and that of spin-density waves has been studied in the field of spintronics. However, less effort has been devoted to combining these two technologies and to developing the expected ultra-high-speed and low-energy-consumption devices. To date, a major obstacle preventing the promotion of this research field has been the lack of a measuring instrument that is sensitive to both charge and spin.
In their recent paper, published in Nature Physics, Dr. Masayuki Hashisaka at Tokyo Tech and colleagues reported a "spin-resolved oscilloscope" that enables measurement of the waveforms of both charge and spin signals in electronic devices. An oscilloscope is a basic measuring instrument used in electronics; however, conventional oscilloscopes do not facilitate both charge and spin measurement.
The "charge signal" is the total charge of the spin-up and -down electron densities. Further, the "spin signal" is the difference between the spin-up and -down electron densities. Both these signals traveling in a semiconductor device can be detected by the spin-resolved oscilloscope, which is composed of a spin filter and nanometer-scale time-resolved charge detectors. The spin filter separates the spin-up and -down electrons, while the time-resolved charge detector measures the waveforms of the charge-density waves. By combining these spintronic and plasmonic devices, the spin-resolved oscilloscope is established.
Scientists from IBM and ETH Zurich university have built a tiny “flow” battery that has the dual benefit of supplying power to chips and cooling them at the same time. Even taking pumping into account, it produces enough energy to power a chip while dissipating much more heat than it generates. The result could be smaller, more efficient chips, solar cells that store their own energy or devices used for remote monitoring that don’t require external power sources.
“Redox flow” batteries that use liquid electrolytes are normally used on a large scale to store energy. For instance, Harvard Researchers recently created one that can last over ten years with very little degradation, making it ideal to store solar or wind energy.
Building them on a scale tiny enough for chips is another matter, however. The team from ETH Zurich and IBM managed to find two liquids that are suitable both as flow-battery electrolytes and cooling agents that can dissipate heat from chips in the same circuit. “We are the first scientists to build such a small flow battery so as to combine energy supply and cooling,” says doctoral student Julian Marschewski.
Why is the sky blue? It’s a common question asked by children, and the simple answer is that blue light is scattered by our atmosphere more than red light, hence the blue sky. That’s basically true, but then why don’t we see a violet sky?
The blue sky we observe depends upon two factors: how sunlight interacts with Earth’s atmosphere, and how our eyes perceive that light.
When light interacts with our atmosphere it can scatter, similar to the way one billiard ball can collide with another, making them go off in different directions. The main form of atmospheric scattering is known as Rayleigh scattering. If you imagine photons bouncing off molecules of air, that’s a rough approximation.
But photons and air molecules aren’t billiard balls, so there are differences. One of these is that the amount of scattering depends upon the wavelength (or color) of the light. The shorter the wavelength, the more the light scatters. Since the rainbow of colors going from red to violet corresponds with wavelengths of light going from long to short, the shorter blue wavelengths are scattered more. So our sky appears blue because of all the scattered blue light. This is also the reason why sunsets can appear red. Blue light is scattered away, leaving a reddish looking sunset.
But if that’s the case, why isn’t the sky violet? Sure, blue light is scattered more than red or green, but violet light has an even shorter wavelength, so violet should be scattered more than blue. Shouldn’t the sky appear violet, or at least a violet-blue? It turns out our sky is indeed violet, but it appears blue because of the way our eyes work.
Microscopic marine plankton are not helplessly adrift in the ocean. They can perceive cues that indicate turbulence, rapidly respond to regulate their behaviour and actively adapt. ETH researchers have demonstrated for the first time how they do this.
Plankton in the ocean are constantly on the move. By day, these tiny organisms, one-tenth the diameter of a human hair, actively migrate towards the sunlit ocean surface to carry out photosynthesis. At night, they make their way to depths of tens of meters, where the supply of nutrients is greater. During their regular trips between well-lit and nutrient-rich zones, plankton cells frequently encounter turbulent layers, which disrupt this essential migratory pattern.
It is still a mystery how these minute organisms can navigate through the dangers of turbulent waters. Plankton cells are whirled around by turbulence -- particularly by the smallest, millimeter-sized flow vortices -- as if they were in a miniature washing machine, which can induce permanent damage to their propulsion appendages and cell envelope. In the worst case, they can perish in turbulence.
Aquila is a conceptual 50-meter sailing yacht that features solar sails thanks to CIGS solar cells technology. This project was born out of the idea to create a new generation of sailing yacht that follows recent trends of implementing futuristic technology in existing transportation. This futuristic sailing yacht features 50 meters length and 11.2 meters beam, it can accommodate up to 10 people at a time.
This yacht design aims to redefine sustain sailing navigation by highlighting its ability to operate entirely on solar power. It uses green technology such as solar sails to operate the electronic systems, this yacht can also generate energy from the wind.
Via Jason Arack
Researchers have developed a novel computational tool to help design single guide RNAs (sgRNAs) for DNA deletion using the CRISPR-Cas system. The new tool, CRISPETa, was reported in PLOS Computational Biology recently.
Since its initial discovery and subsequent development throughout the last decade, CRISPR has become known as a powerful tool in genomic experiments, both for trying to understand the genome and attempting to treat genetic disorders. Several variants of the system have been developed, such as CRISPRi to influence gene expression at a transcription level and dCas9 to bind to the DNA without cleaving the strand. In 2015, Professor Rory Johnson and his team developed another CRISPR variant, known as DECKO, which was designed specifically to facilitate the removal of selected DNA sequences from the genome.
DECKO uses two distinct sgRNAs to guide the cleavage protein Cas9 to the correct sites in the genome on either side of the material being deleted. When the nuclease cleaves the DNA at both sites, the sequence between the two loci is removed completely from the genome with high accuracy. The nature of CRISPR means that DECKO can be used to remove both coding and non-coding material and as a result has become a popular tool among researchers.
During the initial development of DECKO, the team noticed that one of the most time-consuming parts of their experiments was the sgRNA design process because there was no pre-made design software available. Now, Master’s student Carlos Pulido may have created the solution to this problem with a novel software pipeline called CRISPETa, which can suggest sgRNAs based on the intended target region.
Astronomers have found evidence for a star that whips around a black hole about twice an hour. This may be the tightest orbital dance ever witnessed for a black hole and a companion star.
Michigan State University scientists were part of the team that made this discovery, which used NASA's Chandra X-ray Observatory as well as NASA's NuSTAR and the Australia Telescope Compact Array.
The close-in stellar couple -- known as a binary -- is located in the globular cluster 47 Tucanae, a dense cluster of stars in our galaxy about 14,800 light years away from Earth. While astronomers have observed this binary for many years, it wasn't until 2015 that radio observations revealed the pair likely contains a black hole pulling material from a companion star called a white dwarf, a low-mass star that has exhausted most or all of its nuclear fuel.
New Chandra data of this system, known as X9, show that it changes in X-ray brightness in the same manner every 28 minutes, which is likely the length of time it takes the companion star to make one complete orbit around the black hole. Chandra data also shows evidence for large amounts of oxygen in the system a characteristic of white dwarfs. A strong case can, therefore, be made that that the companion star is a white dwarf, which would then be orbiting the black hole at only about 2.5 times the separation between Earth and the moon.
"This white dwarf is so close to the black hole that material is being pulled away from the star and dumped onto a disk of matter around the black hole before falling in," said Arash Bahramian, lead author with the University of Alberta (Canada) and MSU. "Luckily for this star, we don't think it will follow this path into oblivion, but instead will stay in orbit." Although the white dwarf does not appear to be in danger of falling in or being torn apart by the black hole, its fate is uncertain.
"For a long time astronomers thought that black holes were rare or totally absent in globular star clusters," said Jay Strader, MSU astronomer and co-author of the paper. "This discovery is additional evidence that, rather than being one of the worst places to look for black holes, globular clusters might be one of the best."
How did the black hole get such a close companion? One possibility is that the black hole smashed into a red giant star, and then gas from the outer regions of the star was ejected from the binary. The remaining core of the red giant would form into a white dwarf, which becomes a binary companion to the black hole. The orbit of the binary would then have shrunk as gravitational waves were emitted, until the black hole started pulling material from the white dwarf.
The gravitational waves currently being produced by the binary have a frequency that is too low to be detected with Laser Interferometer Gravitational-Wave Observatory, LIGO, that has recently detected gravitational waves from merging black holes. Sources like X9 could potentially be detected with future gravitational wave observatories in space.
Drones could use it — the remarkable hunting ability of the robber fly.
A small fly the size of a grain of rice could be the Top Gun of the fly world, with a remarkable ability to detect and intercept its prey mid-air, changing direction mid-flight if necessary before sweeping round for the kill.
The robber fly Holcocephala is a relatively small fly -- at 6mm in length, it is similar in size of the average mosquito. Yet it has the ability to spot and catch prey more than half a meter away in less than half a second -- by comparison to its size, this would be the equivalent of a human spotting its prey at the other end of a football pitch. Even if the prey changes direction, the predator is able to adapt mid-air and still catch its prey.
An international team led by researchers from the University of Cambridge was able to capture this activity by tricking the fly into launching itself at a fake prey -- in fact, just a small bead on a fishing line. This enabled the team to witness the fly's remarkable aerial attack strategy. Their findings are published today in the journal Current Biology.
The robber fly has incredibly sophisticated eyes: like all flies, it has compound eyes made up of many lenses -- in the case of the robber fly, it is thought to have several thousand lenses per eye. However, unlike many species of fly, it has a range of lens sizes, from just over 20 microns to around 78 microns -- the width of a human hair. The larger lenses are the same size as those of a dragonfly, which is believed to have the best vision of all insects but is 10 times larger, and help reduce diffraction which would otherwise distort the image
"There's a trade-off going on between having excellent vision -- which requires bigger lenses -- and the size of the insect," explains Dr Paloma Gonzalez-Bellido from Cambridge's Department of Physiology, Development and Neuroscience. "The only way a robber fly could have vision as excellent as the 'poster child' of predatory insects, the dragonfly, across its entire visual field would be to have an eye with many more and larger lenses -- but then the fly itself would need to be much larger to be able to carry it."
To get around this problem, the robber fly has a concentration of larger lenses in the centre of its vision, accounting for only around one thousandth of its visual space. The lenses get smaller in size around the outside of the eye. Importantly, the team of researchers also showed that below the very large central lenses, this robber fly has evolved extremely small light detectors, which are placed almost parallel to each other and much further away from the lens than normal. This arrangement preserves the high local image resolution, which is very close to that of much larger dragonflies.
When it sees a potential prey, the fly launches itself upwards while maintaining a 'constant bearing angle' -- in other words, it moves in a direction such that while moving closer and closer to its prey, it still maintains the same relative bearing. This ensures that it will intercept its prey.
"If you think of this as though you're driving along the motorway and a car is coming down the slip road, then if the relative angle between you and this car remains constant, you will collide," explains PhD student Sam Fabian. "Of course, you'd take evasive action, but in the case of the robber fly, this is what it wants."
This strategy of maintaining the constant relative bearing also allows the robber fly to maneuver itself mid-air in the event that its prey changes direction. The researchers demonstrated this by switching the direction of their fake prey while the robber fly was mid-flight and observing how the fly responded. Once the fly is around 29 cm away from its prey -- though exactly how it judges this distance is still unclear -- the fly displays a remarkable strategy never before observed in a flying animal. It 'locks-on' to its prey while changing its own trajectory, enabling it to sweep round, slow down and come alongside the prey to make its final attack.
"What you see is similar to a baton pass in a relay race: when the two runners are heading in a similar direction and speed, they are more likely to be successful than if they are passing each other at ninety degrees," says Dr Trevor Wardill.
New NASA research reveals that the giant Martian shield volcano Arsia Mons produced one new lava flow at its summit every 1 to 3 million years during the final peak of activity. The last volcanic activity there ceased about 50 million years ago—around the time of Earth's Cretaceous-Paleogene extinction, when large numbers of our planet's plant and animal species (including dinosaurs) went extinct.
A landslide on comet 67P/Churyumov–Gerasimenko triggered a plume of dust to be ejected, revealing pristine ice hidden beneath the surface.
In July 2015, the Rosetta spacecraft observed an outburst from the comet. Images from on board cameras had shown numerous surface changes taking place over the two years of observation. However, one in particular was of interest to researchers.
Outbursts are often seen on comets, but what causes them is not known. To understand what happens on the surface at the point of these outbursts, an international team of researchers studied an event on Comet 67P.
In two studies – one published in Nature Astronomy, the other in Science – researchers showed that landslides had taken place on the comet, with whole cliffs collapsing, drastically altering the surface landscape.
Cerealia Facula, a dome-like feature located in the center of Ceres’ Occator crater, is only 4 million years old -- approximately 30 million years younger than the crater itself, according to research led by Dr. Andreas Nathues of the Max Planck Institute for Solar System Research.
Occator crater is one of the largest craters on the dwarf planet Ceres. With a diameter of 57 miles (92 km), it is larger than Tycho crater on the Moon. Its steep walls stand tall at over 1.4 miles (2 km), higher than the North face of the Eiger in the Bernese Alps.
“Occator crater is located in the northern hemisphere of Ceres. In its center a pit with a diameter of about 6.8 miles (11 km) can be found. On some parts of its edges, jagged mountains and steep slopes rise up to 2,460 feet (750 m) high,” Dr. Nathues and co-authors said. “Within the pit a bright dome formed. It is 1,312 feet (400 m) high, has a diameter of 1.9 miles (3 km), and displays prominent fractures.”
“This dome, called Cerealia Facula, contains the brightest material on Ceres.”
The researchers analyzed data from two instruments on board NASA’s Dawn spacecraft: the framing camera, and the visible and infrared spectrometer (VIR). VIR data show that Cerealia Facula is very rich in carbonate salts.
Since later impacts in this area did not expose any other material from the depth, this feature possibly consists entirely of bright material. The secondary, smaller bright areas of Occator, called Vinalia Faculae, are paler, form a thinner layer and — as VIR and camera data show — turn out to be a mixture of carbonates and dark surrounding material.
New evidence also suggests that Cerealia Facula likely rose in a process that took place over a long period of time, rather than forming in a single event. Dr. Nathues and his colleagues believe the initial trigger was the impact that dug out Occator crater. This impact happened some 34 million years ago and caused briny liquid to rise closer to the surface.
SpaceX has applied to the FCC to launch 11,943 satellites into low-Earth orbit, providing “ubiquitous high-bandwidth (up to 1Gbps per user, once fully deployed) broadband services for consumers and businesses in the U.S. and globally,” according to FCC applications. Recent meetings with the FCC suggest that the plan now looks like “an increasingly feasible reality — particularly with 5G technologies just a few years away, promising new devices and new demand for data,” Verge reports.
Such a service will be particularly useful to rural areas, which have limited access to internet bandwidth. Low-Earth orbit (at up to 2,000 kilometers, or 1,200 mi) ensures lower latency (communication delay between Earth and satellite) — making the service usable for voice communications via Skype, for example — compared to geosynchronous orbit (at 35,786 kilometers, or 22,000 miles), offered by Dish Network and other satellite ISP services.* The downside: it takes a lot more satellites to provide the coverage.
Boeing, Softbank-backed OneWeb (which hopes to “connect every school to the Internet by 2022″), Telesat, and others** have proposed similar services, possibly bringing the total number of satellites to about 20,000 in low and mid earth orbits in the 2020s, estimates Next Big Future.
Scientists are planning to capture the first ever photo of a black hole’s event horizon (the boundary of no return that light can’t event escape). The project is called the Event Horizon Telescope, and it uses a network of 9 radio telescopes found across the world that will be pointed at Sagittarius A*, the black hole 25,000 light years away at the center of our Milky Way galaxy.
Scientists say that calculations and preparations are done, and that they’re aiming to shoot the groundbreaking photo sometime early this year. “There are quite a few challenges that need to be overcome to take a picture of a black hole – it’s something that’s extremely small in the sky,” EHT scientist Feryal Ozel explains. “But what we’re hoping for is a full array observation in early 2017.”
Although our entire galaxy revolves around it, Sagittarius A* has an event horizon with a diameter of 24 million km (~14.9 million miles), or about 17 times that of our Sun. And since it’s so far away, to us it’s about the relative size of a CD on the surface of the moon, scientists say.
So what will the resulting photo look like? Scientists are predicting that it will look like a crescent of light around a black hole due to the Doppler effect making part of the ring brighter than the other. Here’s the “close up” view of a black hole that was computer generated for the movie Interstellar (created under the guidance of renowned astrophysicist Kip Thorne).
Although the invisible substance known as dark matter dominates galaxies nowadays, it was apparently only a minor ingredient of galaxies in the early universe, a new study finds.
This new finding sheds light on how galaxies and their mysterious "haloes" of dark matter have changed over time, researchers said.
Dark matter is thought to make up about 84 percent of the matter in the universe. Although dark matter is invisible, its presence can be inferred by its gravitational effects on visible matter. For instance, previous work discovered that the outer parts of galactic disks whirl faster than expected around the cores of those galaxies. These findings make sense if one assumes that "haloes" of dark matter envelop those galaxies and gravitationally pull at their outer regions. [The Search for Dark Matter in Pictures]
Now, the researchers unexpectedly find that in the early universe, dark matter played a much smaller role in galaxies than previously thought. The scientists detailed their findings in the March 16 issue of the journal Nature.
Using the European Southern Observatory's Very Large Telescope in Chile, the researchers examined six massive, star-forming galaxies from the early universe during the peak of galaxy formation 10 billion years ago. They analyzed the rotation of these galaxies to calculate how much dark matter they possessed.
When it comes to the Milky Way and other typical galaxies born in the current era of the universe, their "effective radius"—that is, the bright region that half their light comes from—is 50 to 80 percent dark matter, said study lead author Reinhard Genzel, an astrophysicist and director of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany. In comparison, in half the early galaxies the researchers studied, dark matter made up 10 percent or less of the galaxies' effective radius, Genzel said.
Slow wi-fi is a source of irritation that nearly everyone experiences. Wireless devices in the home consume ever more data, and it’s only growing, and congesting the wi-fi network. Researchers at Eindhoven University of Technology have come up with a surprising solution: a wireless network based on harmless infrared rays. The capacity is not only huge (more than 40Gbit/s per ray) but also there is no need to share since every device gets its own ray of light. This was the subject for which TU/e researcher Joanne Oh received her PhD degree with the ‘cum laude’ distinction last week.
The system conceived in Eindhoven is simple and, in principle, cheap to set up. The wireless data comes from a few central ‘light antennas’, for instance mounted on the ceiling, which are able to very precisely direct the rays of light supplied by an optical fiber. Since there are no moving parts, it is maintenance-free and needs no power: the antennas contain a pair of gratings that radiate light rays of different wavelengths at different angles (‘passive diffraction gratings’). Changing the light wavelengths also changes the direction of the ray of light. Since a safe infrared wavelength is used that does not reach the vulnerable retina in your eye, this technique is harmless.
If you walk around as a user and your smartphone or tablet moves out of the light antenna’s line of sight, then another light antenna takes over. The network tracks the precise location of every wireless device using its radio signal transmitted in the return direction. It is a simple matter to add devices: they are assigned different wavelengths by the same light antenna and so do not have to share capacity. Moreover, there is no longer any interference from a neighboring wi-fi network.
Data capacity of light rays
Current wi-fi uses radio signals with a frequency of 2.5 or 5 gigahertz. The system conceived at TU Eindhoven uses infrared light with wavelengths of 1500 nanometers and higher; this light has frequencies that are thousands of times higher, some 200 terahertz, which makes the data capacity of the light rays much larger. Joanne Oh even managed a speed of 42.8 Gbit/s over a distance of 2.5 meters. For comparison, the average connection speed in the Netherlands is two thousand times less (17.6 Mbit/s). Even if you have the very best wi-fi system available, you won’t get more than 300 Mbit/s in total, which is some hundred times less than the speed per ray of light achieved by the Eindhoven study.
Researchers from The University of Manchester have shown that it is possible to build a new super-fast form of computer that “grows as it computes”.
Via Integrated DNA Technologies
Are animals on Earth about to get a lot smaller? If the past is any guide, perhaps the answer is yes.
Carbon signatures in the geological record show that global temperature surged 5 to 8 degrees Celsius within 10,000 years.
They also indicate that the planet’s temperature remained elevated for an additional 170,000 years before returning to normal.
Scientists describe this (relatively) rapid rise in temperature as a “hyperthermal event,” and it is not the only one that has ever occurred. About 2 million years later, the Earth experienced another surge in temperature that was about half the magnitude of its predecessor.
Over the course of Earth’s history there have been other, smaller hyperthermal events as well. Most scientists would agree that we are in the midst of one right now.
Abigail D’Ambrosia, a graduate student at the University of New Hampshire, is interested in what happens to living things when the global temperature jumps. Do they go extinct? Do they adapt? Do they change?
Her research, published in Science Advances, shows that at least in the case of some mammals, they shrink.
Via SustainOurEarth, CineversityTV
Lawrence Livermore National Laboratory weapon physicist Greg Spriggs gives researchers a new way to study the power of nuclear weaponry.
A treasure trove of footage from early U.S. nuclear weapons tests has just been declassified and uploaded to YouTube.
The film release was part of a project headed by Lawrence Livermore National Laboratory (LLNL) weapons physicist Greg Spriggs which aimed to digitize and preserve thousands of films documenting the nation’s nuclear history. The endeavor required an all-hands-on deck approach from archivists, film experts and software engineers, but the team says that this digitized database is already yielding new insights from the decades-old tests.
The films all stem from the 210 atmospheric nuclear tests undertaken by the U.S. between 1945 and 1962. There are an estimated 10,000 films from these tests, capturing multiple angles and data points. The project has so far tracked down 6,500 of them, and converted 4,200 to a digital format—750 have so far been declassified, and this week’s batch is the first to be released.
Preserving the films wasn’t easy. It required modifying equipment to match the specifications of the old film, and locating data logs that provide critical information about camera placement, speed and focal length. Then, they watched each film to determine the exact frame rate, as it was known to vary from camera to camera at the time. Several programmers assisted Spriggs’ team and provided computational tools to analyze films frame-by-frame—a task that was once done by hand. Once a film was digitized and the relevant information matched to each, it can be used to study the behavior of nuclear weapons.
The videos include several of the major nuclear weapons testing runs from the era, including Operations Plumbbob and Dominic. The tests were mostly conducted at sites in Nevada or on atolls in the middle of the Pacific Ocean. Several of the early tests would raise concerns over the fallout from nuclear device testing, both on soldiers involved in exercises nearby and on civilians in the surrounding areas.
The films were originally meant for researchers, to be used as study guides for the next round of development and testing. In the years following the first nuclear explosion, the Trinity test in New Mexico on July 16, 1945, researchers raced to comprehend the magnitude of their creation.
The hundreds of tests that followed comprised an array of bomb designs and testing environments, including underground, underwater and high-altitude tests. The videos of these events were obsessively studied frame by frame to gauge the magnitude of the explosion by looking at its brightness and shockwave, as well as the effects on nearby military equipment, towns and livestock.
Looking back through the footage today, Spriggs says it’s apparent some the data gathered 60 years ago is incorrect. With the benefit of modern-day technology, he is hoping to rectify those mistakes and provide accurate information after all this time. “When you go to validate your computer codes, you want to use the best data possible,” he says. “We were finding that some of these answers were off by 20, maybe 30, percent. That’s a big number for doing code validation. One of the payoffs of this project is that we’re now getting very consistent answers. We’ve also discovered new things about these detonations that have never been seen before. New correlations are now being used by the nuclear forensics community, for example.”
A new study reveals some stunning estimates about just how much the world's spiders eat annually: between 400 and 800 million tons of insects, springtails, and other invertebrates. For a sense of just how much this is, take the following into account: all humans together consume an estimated 400 million tons of meat and fish annually. Whales feed on 280 to 500 million tons of seafood, while the world's total seabird population eats an estimated 70 million tons of fish and other seafood.
In the process of eating all these insects, these eight-legged carnivores play an important role to keep countless insect pests, especially in forests and grassland areas, in check. This is according to the findings of Martin Nyffeler of the University of Basel in Switzerland and Klaus Birkhofer of Lund University in Sweden and the Brandenburg University of Technology Cottbus-Senftenberg in Germany, published in Springer's journal The Science of Nature.
Using data from 65 previous studies, Nyffeler and Birkhofer first estimated how many spiders are currently to be found in seven biomes on the planet. Their conclusion: altogether there are about 25 million metric tons' worth of them around. Most spiders are found in forests, grasslands and shrublands, followed by croplands, deserts, urban areas and tundra areas.
The researchers then used two simple models to calculate how much prey all the world's spiders as a whole kill per year. In their first approach, they took into account how much most spiders generally need to eat to survive, as well as census data on the average spider biomass per square meter in the various biomes. The second approach was based on prey capture observations in the field, combined with estimates of spider numbers per square meter. According to their extrapolations, 400 to 800 million tons of prey are being killed by spiders each year.
According to further calculations, spiders in forests and grasslands account for more than 95 percent of the annual prey kill of the global spider community. The figure reflects the fact that forests, grasslands and savannas are less frequently disturbed than for instance agricultural or urban areas, and therefore allow for greater spider biomass.
"These estimates emphasize the important role that spider predation plays in semi-natural and natural habitats, as many economically important pests and disease vectors breed in those forest and grassland biomes," says lead author Martin Nyffeler.
According to the researchers, spiders are not only important predators, but are also valuable sources of prey. Between 8,000 and 10,000 other predators, parasitoids and parasites feed exclusively on spiders, while spiders at the same time form an important part of the diet of an estimated 3,000 to 5,000 bird species.
"We hope that these estimates and their significant magnitude raise public awareness and increase the level of appreciation for the important global role of spiders in terrestrial food webs," adds Nyffeler.
Extremely short, configurable "femtosecond" pulses of light demonstrated by an international team could lead to future computers that run up to 100,000 times faster than today's electronics.
The researchers, including engineers at the University of Michigan, showed that they could control the peaks within the laser pulses and also twist the light. The method moves electrons faster and more efficiently than electrical currents -- and with reliable effects on their quantum states. It is a step toward so-called "lightwave electronics" and, in the more distant future, quantum computing, said Mackillo Kira, U-M professor of electrical engineering and computer science who was involved in the research.
Electrons moving through a semiconductor in a computer, for instance, occasionally run into other electrons, releasing energy in the form of heat. But a concept called lightwave electronics proposes that electrons could be guided by ultrafast laser pulses. While high speed in a car makes it more likely that a driver will crash into something, high speed for an electron can make the travel time so short that it is statistically unlikely to hit anything.
"In the past few years, we and other groups have found that the oscillating electric field of ultrashort laser pulses can actually move electrons back and forth in solids," said Rupert Huber, professor of physics at the University of Regensburg who led the experiment. "Everybody was immediately excited because one may be able to exploit this principle to build future computers that work at unprecedented clock rates -- 10 to a hundred thousand times faster than state-of-the-art electronics."
But first, researchers need to be able to control electrons in a semiconductor. This work takes a step toward this capability by mobilizing groups of electrons inside a semiconductor crystal using terahertz radiation -- the part of the electromagnetic spectrum between microwaves and infrared light. The researchers shone laser pulses into a crystal of the semiconductor gallium selenide. These pulses were very short at less than 100 femtoseconds, or 100 quadrillionths of a second. Each pulse popped electrons in the semiconductor into a higher energy level -- which meant that they were free to move around -- and carried them onward. The different orientations of the semiconductor crystal with respect to the pulses meant that electrons moved in different directions through the crystal -- for instance, they could run along atomic bonds or in between them.
"The different energy landscapes can be viewed as a flat and straight street for electrons in one crystal direction, but for others, it may look more like an inclined plane to the side," said Fabian Langer, a doctoral student in physics at Regensburg. "This means that the electrons may no longer move in the direction of the laser field but perform their own motion dictated by the microscopic environment."
When the electrons emitted light as they came down from the higher energy level, their different journeys were reflected in the pulses. They emitted much shorter pulses than the electromagnetic radiation going in. These bursts of light were just a few femtoseconds long. Inside a crystal, they are quick enough to take snapshots of other electrons as they move among the atoms, and they could also be used to read and write information to electrons. For that, researchers would need to be able to control these pulses -- and the crystal provides a range of tools.
"There are fast oscillations like fingers within a pulse. We can move the position of the fingers really easily by turning the crystal," said Kira, whose group worked with researchers at the University of Marburg, Germany, to interpret Huber's experiment.
The crystal could also twist the outgoing light waves or not, depending on its orientation to the incoming laser pulses.
Because femtosecond pulses are fast enough to intercept an electron between being put into an excited state and coming down from that state, they can potentially be used for quantum computations using electrons in excited states as qubits.
What caused the largest glaciation event in Earth's history, known as 'snowball Earth'? Geologists and climate scientists have been searching for the answer for years but the root cause of the phenomenon remains elusive.
Now, Harvard University researchers have a new hypothesis about what caused the runaway glaciation that covered Earth pole-to-pole in ice. The research is published in Geophysical Research Letters.
Researchers have pinpointed the start of what's known as the Sturtian snowball Earth event to about 717 million years ago -- give or take a few 100,000 years. At around that time, a huge volcanic event devastated an area from present-day Alaska to Greenland. Coincidence?
Harvard professors Francis Macdonald and Robin Wordsworth thought not. "We know that volcanic activity can have a major effect on the environment, so the big question was, how are these two events related," said Macdonald, the John L. Loeb Associate Professor of the Natural Sciences.
At first, Macdonald's team thought basaltic rock -- which breaks down into magnesium and calcium -- interacted with CO2 in the atmosphere and caused cooling. However, if that were the case, cooling would have happened over millions of years and radio-isotopic dating from volcanic rocks in Arctic Canada suggest a far more precise coincidence with cooling.
Macdonald turned to Wordsworth, who models climates of non-Earth planets, and asked: could aerosols emitted from these volcanos have rapidly cooled Earth? The answer: yes, under the right conditions.
"It is not unique to have large volcanic provinces erupting," said Wordsworth, assistant professor of Environmental Science and Engineering at the Harvard John A. Paulson School of Engineering and Applied Science. "These types of eruptions have happened over and over again throughout geological time but they're not always associated with cooling events. So, the question is, what made this event different?"
Geological and chemical studies of this region, known as the Franklin large igneous province, showed that volcanic rocks erupted through sulfur-rich sediments, which would have been pushed into the atmosphere during eruption as sulfur dioxide. When sulfur dioxide gets into the upper layers of the atmosphere, it's very good at blocking solar radiation. The 1991 eruption of Mount Pinatubo in the Philippines, which shot about 10 million metric tons of sulfur into the air, reduced global temperatures about 1 degree Fahrenheit for a year.
Sulfur dioxide is most effective at blocking solar radiation if it gets past the tropopause, the boundary separating the troposphere and stratosphere. If it reaches this height, it's less likely to be brought back down to earth in precipitation or mixed with other particles, extending its presence in the atmosphere from about a week to about a year. The height of the tropopause barrier all depends on the background climate of the planet -- the cooler the planet, the lower the tropopause.
"In periods of Earth's history when it was very warm, volcanic cooling would not have been very important because Earth would have been shielded by this warm, high tropopause," said Wordsworth. "In cooler conditions, Earth becomes uniquely vulnerable to having these kinds of volcanic perturbations to climate."