The Moon may play a major role in maintaining Earth's magnetic field

The Earth's magnetic field permanently protects us from the charged particles and radiation that originate in the Sun. This shield is produced by the geodynamo, the rapid motion of huge quantities of liquid iron alloy in the Earth's outer core. To maintain this magnetic field until the present day, the classical model required the Earth's core to have cooled by around 3 000 °C over the past 4.3 billion years. Now, astronomers suggest that, on the contrary, its temperature has fallen by only 300 °C. The action of the Moon, overlooked until now, is thought to have compensated for this difference and kept the geodynamo active.

The gravitational effects associated with the presence of the Moon and Sun cause cyclical deformation of the Earth's mantle and wobbles in its rotation axis. This mechanical forcing applied to the whole planet causes strong currents in the outer core, which is made up of a liquid iron alloy of very low viscosity. Such currents are enough to generate the Earth's magnetic field.

The Earth's magnetic field permanently protects us from the charged particles and radiation that originate in the Sun. This shield is produced by the geodynamo, the rapid motion of huge quantities of liquid iron alloy in the Earth's outer core. To maintain this magnetic field until the present day, the classical model required the Earth's core to have cooled by around 3,000 °C over the past 4.3 billion years. Now, a team of researchers from CNRS and Université Blaise Pascal[1] suggests that, on the contrary, its temperature has fallen by only 300 °C. The action of the Moon, overlooked until now, is thought to have compensated for this difference and kept the geodynamo active. Their work is published on 30 march 2016 in the journal Earth and Planetary Science Letters.

The classical model of the formation of Earth's magnetic field raised a major paradox. For the geodynamo to work, the Earth would have had to be totally molten four billion years ago, and its core would have had to slowly cool from around 6800 °C at that time to 3800 °C today. However, recent modeling of the early evolution of the internal temperature of the planet, together with geochemical studies of the composition of the oldest carbonatites and basalts, do not support such cooling. With such high temperatures being ruled out, the researchers propose another source of energy in their study.

The Earth has a slightly flattened shape and rotates about an inclined axis that wobbles around the poles. Its mantle deforms elastically due to tidal effects caused by the Moon. The researchers show that this effect could continuously stimulate the motion of the liquid iron alloy making up the outer core, and in return generate Earth's magnetic field. The Earth continuously receives 3,700 billion watts of power through the transfer of the gravitational and rotational energy of the Earth-Moon-Sun system, and over 1,000 billion watts is thought to be available to bring about this type of motion in the outer core. This energy is enough to generate the Earth's magnetic field, which together with the Moon, resolves the major paradox in the classical theory. The effect of gravitational forces on a planet's magnetic field has already been well documented for two of Jupiter's moons, Io and Europa, and for a number of exoplanets.

Since neither the Earth's rotation around its axis, nor the direction of its axis, nor the Moon's orbit are perfectly regular, their combined effect on motion in the core is unstable and can cause fluctuations in the geodynamo. This process could account for certain heat pulses in the outer core and at its boundary with the Earth's mantle.

Over the course of time, this may have led to peaks in deep mantle melting and possibly to major volcanic events at the Earth's surface. This new model shows that the Moon's effect on the Earth goes well beyond merely causing tides.

Flexible energy storage is smaller, cheaper, better

Engineers have developed a way to make a magnetic material that could lead to lighter and smaller, cheaper and better-performing high-frequency transformers, needed for more flexible energy storage systems and widespread adoption of renewable energy.

A Sandia-led team has developed a way to make a magnetic material that could lead to lighter and smaller, cheaper and better-performing high-frequency transformers, needed for more flexible energy storage systems and widespread adoption of renewable energy.

The work is part of a larger, integrated portfolio of projects funded by Department of Energy's (DOE) Energy Storage Program in the Office of Electricity Delivery and Energy Reliability.

Transportable energy storage and power conversion systems, which can fit inside a single semi-trailer, could make it cost effective to rapidly install solar, wind and geothermal energy systems in even the most remote locations.

"Such modular systems could be deployed quickly to multiple sites with much less assembly and validation time," said Sandia researcher Todd Monson of Nanoscale Sciences Department, who led the team with Stan Atcitty of Sandia's Energy Storage Technology & Systems Department.

Sandia manufactures iron nitride (γ'-Fe4N) powders by ball-milling iron powders in liquid nitrogen and then ammonia. The iron nitride powders are then consolidated through a low-temperature field-assisted sintering technique (FAST) that forms a solid material from loose powders through the application of heat and sometimes pressure.

The FAST manufacturing method enables the creation of transformer cores from raw starting materials in minutes, without decomposing the required iron nitrides, as could happen at the higher temperatures used in conventional sintering. Previously, the γ' phase of iron nitride has only been synthesized in either thin-film form in high-vacuum environments or as inclusions in other materials, and never integrated into an actual device.

Monson said using this method could make transformers up to 10 times smaller than they are currently.

No machining required

"FAST enables the net-shaping of parts, meaning that iron nitride powders can be sintered directly into perfectly sized parts, such as transformer cores, which don't require any machining," Monson said.

Due to its magnetic properties, iron nitride transformers can be made much more compact and lighter than traditional transformers, with better power-handling capability and greater efficiency. They will require only air cooling, another important space saver. Iron nitride also could serve as a more robust, high-performance transformer core material across the nation's electrical grid.

So far, Monson and his colleagues have demonstrated the fabrication of iron nitride transformer cores with good physical and magnetic characteristics and now are refining their process and preparing to test the transformers in power-conversion test beds.

"Advanced magnetic materials are critical for next-generation power conversion systems that use high-frequency linked converters, and can complement Sandia efforts in ultra-wide bandgap device materials for improved power electronics systems. They can withstand higher frequencies and higher temperatures, which ultimately result in high power density designs," said Atcitty.

Monson, Atcitty and their team built on Sandia's expertise in power electronics and magnetic materials in strong collaborations with University of California, Irvine, and Arizona State University researchers, who helped with materials processing and systems-level modeling.

Team members from Sandia and UC Irvine have filed a patent application for the materials synthesis process.

"Power electronics represents a substantial cost factor in an effective energy storage system," said Imre Gyuk, Energy Storage program manager in the DOE's Office of Electricity Delivery and Energy Reliability.

Smartwatches can now track your finger in mid-air using sonar

A new sonar technology developed by computer scientists and electrical engineers allows you to interact with mobile devices and smartwatch screens by writing or gesturing on any nearby surface -- a tabletop, a sheet of paper or even in mid-air.

As mobile and wearable devices such as smartwatches grow smaller, it gets tougher for people to interact with screens the size of a matchbook.

That could change with a new sonar technology developed by University of Washington computer scientists and electrical engineers that allows you to interact with mobile devices by writing or gesturing on any nearby surface -- a tabletop, a sheet of paper or even in mid-air.

FingerIO tracks fine-grained finger movements by turning a smartphone or smartwatch into an active sonar system using the device's own microphones and speakers.

Because sound waves travel through fabric and do not require a line of sight, users can even interact with a phone inside a front pocket or a smartwatch hidden under a sweater sleeve.

In a paper to be presented in May at the Association for Computing Machinery's CHI 2016 conference in San Jose, California, the UW team demonstrates that FingerIO can accurately track two-dimensional finger movements to within 8mm, which is sufficiently accurate to interact with today's mobile devices. The work was recognized with an honorable mention award by the conference.

"You can't type very easily onto a smartwatch display, so we wanted to transform a desk or any area around a device into an input surface," said lead author Rajalakshmi Nandakumar, a UW doctoral student in computer science and engineering. "I don't need to instrument my fingers with any other sensors -- I just use my finger to write something on a desk or any other surface and the device can track it with high resolution."

Using FingerIO, one could use the flick of a finger to turn up the volume, press a button, or scroll through menus on a smartphone without touching it, or even write a search command or text in the air rather than typing on a tiny screen.

FingerIO turns a smartwatch or smartphone into a sonar system using the device's own speaker to emit an inaudible sound wave. That signal bounces off the finger, and those "echoes" are recorded by the device's microphones and used to calculate the finger's location in space.

Using sound waves to track finger motion offers several advantages over cameras -- which don't work without line-of-sight when the device is hidden by fabric or another obstructions -- and other technologies like radar that require both custom sensor hardware and greater computing power, said senior author and UW assistant professor of computer science and engineering Shyam Gollakota.

"Acoustic signals are great -- because sound waves travel much slower than the radio waves used in radar, you don't need as much processing bandwidth so everything is simpler," said Gollakota, who directs the UW's Networks and Mobile Systems Lab. "And from a cost perspective, almost every device has a speaker and microphones so you can achieve this without any special hardware."

But sonar echoes are weak and typically not accurate enough to track finger motion at a high resolution. Errors of a few centimeters make it impossible to differentiate between writing individual letters or subtle hand gestures.

The UW researchers employed a type of signal typically used in wireless communication -- called Orthogonal Frequency Division Multiplexing -- and demonstrated that it can be used to achieve high-resolution finger tracking using sound. Their algorithms leverage the properties of OFDM signals to track phase changes in the echoes and correct for any errors in the finger location to achieve sub-centimeter finger tracking.

To test their approach, the researchers created a FingerIO prototype app for Android devices and downloaded it to an off-the-shelf Samsung Galaxy S4 smartphone and a smartwatch customized with two microphones, which are needed to track finger motion in two dimensions. Today's smartwatches typically only have one, which can be used to track a finger in one dimension.

The researchers asked testers to draw shapes such as stars, squiggles or figure 8s on a touchpad next to a smartphone or smartwatch running FingerIO. Then they compared the touchpad tracings to the shapes created by FingerIO's tracking.

The average difference between the drawings and the FingerIO tracings was 0.8 centimeters for the smartphone and 1.2 centimeters for the smartwatch.

"Given that your finger is already a centimeter thick, that's sufficient to accurately interact with the devices," said co-author and electrical engineering graduate student Vikram Iyer.

Next steps for the research team include demonstrating how FingerIO can be used to track multiple fingers moving at the same time, and extending its tracking abilities into three dime

Young sun-like star shows a magnetic field was critical for life on the early Earth

Nearly four billion years ago, life arose on Earth. Life appeared because our planet had a rocky surface, liquid water, and a blanketing atmosphere. But life thrived thanks to another necessary ingredient: the presence of a protective magnetic field. A new study of the young, Sun-like star Kappa Ceti shows that a magnetic field plays a key role in making a planet conducive to life.

 

Nearly four billion years ago, life arose on Earth. Life appeared because our planet had a rocky surface, liquid water, and a blanketing atmosphere. But life thrived thanks to another necessary ingredient: the presence of a protective magnetic field. A new study of the young, Sun-like star Kappa Ceti shows that a magnetic field plays a key role in making a planet conducive to life.

"To be habitable, a planet needs warmth, water, and it needs to be sheltered from a young, violent Sun," says lead author Jose-Dias Do Nascimento of the Harvard-Smithsonian Center for Astrophysics (CfA) and University of Rio G. do Norte (UFRN), Brazil.

Kappa Ceti, located 30 light-years away in the constellation Cetus, the Whale, is remarkably similar to our Sun but younger. The team calculates an age of only 400-600 million years old, which agrees with the age estimated from its rotation period (a technique pioneered by CfA astronomer Soren Meibom). This age roughly corresponds to the time when life first appeared on Earth. As a result, studying Kappa Ceti can give us insights into the early history of our solar system.

Like other stars its age, Kappa Ceti is very magnetically active. Its surface is blotched with many giant starspots, like sunspots but larger and more numerous. It also propels a steady stream of plasma, or ionized gases, out into space. The research team found that this stellar wind is 50 times stronger than our Sun's solar wind.

Such a fierce stellar wind would batter the atmosphere of any planet in the habitable zone, unless that planet was shielded by a magnetic field. At the extreme, a planet without a magnetic field could lose most of its atmosphere. In our solar system, the planet Mars suffered this fate and turned from a world warm enough for briny oceans to a cold, dry desert.

The team modeled the strong stellar wind of Kappa Ceti and its effect on a young Earth. The early Earth's magnetic field is expected to have been about as strong as it is today, or slightly weaker. Depending on the assumed strength, the researchers found that the resulting protected region, or magnetosphere, of Earth would be about one-third to one-half as large as it is today.

"The early Earth didn't have as much protection as it does now, but it had enough," says Do Nascimento.

Kappa Ceti also shows evidence of "superflares" -- enormous eruptions that release 10 to 100 million times more energy than the largest flares ever observed on our Sun. Flares that energetic can strip a planet's atmosphere. By studying Kappa Ceti, researchers hope to learn how frequently it produces superflares, and therefore how often our Sun might have erupted in its youth.

Clocking the rotation rate of a supermassive black hole

The rotational rate of one of the most massive black holes in the universe has been accurately measured by an international team of astronomers, using several optical telescopes and NASA's SWIFT X-ray telescope. The rotational rate of this massive black hole is one third of the maximum spin rate allowed in General Relativity. This 18 billion solar mass heavy black hole powers a quasar OJ287 which lies about 3.5 billion light years away from Earth.

A recent observational campaign involving more than two dozen optical telescopes and NASA's space based SWIFT X-ray telescope allowed a team of astronomers to measure very accurately the rotational rate of one of the most massive black holes in the universe. The rotational rate of this massive black hole is one third of the maximum spin rate allowed in General Relativity. This 18 billion solar mass heavy black hole powers a quasar called OJ287 which lies about 3.5 billion light years away from Earth. Quasi-stellar radio sources or `quasars' for short, are the very bright centers of distant galaxies which emit huge amounts of electro-magnetic radiation due to the infall of matter into their massive black holes.

This quasar lies very close to the apparent path of the Sun's motion on the celestial sphere as seen from Earth, where most searches for asteroids and comets are conducted. Therefore, its optical photometric measurements already cover more than 100 years. A careful analysis of these observations show that OJ 287 has produced quasi-periodic optical outbursts at intervals of approximately 12 years dating back to around 1891. Additionally, a close inspection of newer data sets reveals the presence of double-peaks in these outbursts.

These deductions prompted Prof. Mauri Valtonen of University of Turku, Finland and his collaborators to develop a model that requires the quasar OJ287 to harbour two unequal mass black holes. Their model involves a massive black hole with an accretion disk (a disk of interstellar material formed by matter falling into objects like black holes) while the comparatively smaller black hole revolves around it. The quasar OJ287 is visible due to the slow accretion of matter, present in the accretion disk, onto the largest black hole. Additionally, the small black hole passes through the accretion disk during its orbit which causes the disk material to heat up to very high temperatures. This heated material flows out from both sides of the accretion disk and radiates strongly for weeks. This causes peaks in the brightness, and the double peaks arise due to the ellipticity of the orbit, as shown in the figure.

The binary black hole model for OJ287 implies that the smaller black hole's orbit should rotate, and this changes where and when the smaller hole impacts the accretion disk. This effect arises from Einstein's General Theory of Relativity and its precessional rate depends mainly on the two black hole masses and the rotation rate of the more massive black hole. In 2010, Valtonen and collaborators used eight well timed bright outbursts of OJ287 to accurately measure the precession rate of the smaller hole's orbit. This analysis revealed for the first time the rotation rate of the massive black hole along with accurate estimates for the masses of the two black holes. This was possible since the smaller black hole's orbit precess at an incredible 39 degrees per individual orbit. The General Relativistic model for OJ287 also predicted that the next outburst could occur around the time of GR Centenary, 25 November 2015, which marks the 100th anniversary of Einstein's General Theory of Relativity.

An observational campaign was therefore launched to catch this predicted outburst. The predicted optical flare began around November 18, 2015 and reached its maximum brightness on December 4, 2015. It is the timing of this bright outburst that allowed Valtonen and his co-workers to directly measure the rotation rate of the more massive black hole to be one third of the maximum spin rate allowed in General Relativity. In other words, its Kerr parameter is accurately measured to be 0.31 and its maximum allowed value in General Relativity is one. In comparison, the Kerr parameter of the final black hole associated with the first ever direct detection of gravitational waves is only estimated to be below 0.7.

The observations leading to accurate spin measurement have been made due to the collaboration of a number of optical telescopes in Japan, South Korea, India, Turkey, Greece, Finland, Poland, Germany, UK, Spain, USA and Mexico. The effort, led by Staszek Zola of Poland, involved close to 100 astronomers from these countries. Interestingly, a number of key participants were amateur astronomers who operate their own telescopes. Valtonen's team that developed and contributed to the spinning binary black hole model include theoretical astrophysicist A. Gopakumar from TIFR, India, and Italian X-Ray astronomer Stefano Ciprini who obtained and analyzed the X-ray data.

The occurrence of the predicted optical outburst of OJ287 also allowed the team to confirm the loss of orbital energy to gravitational waves within two percent of General Relativity's prediction. This provides the first indirect evidence for the existence of a massive spinning black hole binary emitting gravitational waves. This is encouraging news for the Pulsar Timing Array efforts that will directly detect gravitational waves from such systems in the near future. Therefore, the present optical outburst of OJ287 makes a fitting contribution to the centenary celebrations of General Relativity and adds to the excitement of the first direct observation of a transient gravitational wave signal by LIGO.

Android 6.0 Marshmallow

Android 6.0 Marshmallow Update Status For Galaxy Note 5, S6 Edge+, S6, S6 Edge, Note 4, Edge, S5, Alpha, A7, A5, A3, Galaxy Tab S2

The Android 6.0 Marshmallow OTA update has already been released by Samsung for the Galaxy S6 and Galaxy S6 Edge smartphones. However, it is yet to rollout Android 6.0 update for other smartphones. Now, a newly leaked Marshmallow update roadmap has surfaced, revealing when would devices like S6 Edge+, Note 5, Note 4, Note Edge and other models would receive the software update.

Phone Arena has reported that the Galaxy Note 5 and Galaxy S6 Edge+ would start receiving the update from this month. The Galaxy S6 and Galaxy S6 Edge users outside the U.S. and South Korea would also be receiving the Marshmallow update in this month.

The Galaxy Note 4 and the Galaxy Note Edge smartphones from 2014 are slated to get updated to Android 6.0 in the next month. The Samsung Galaxy S5 from 2014 would getting the Android 6.0 software in May 2016. The 8-inch and 9.7-inch Samsung Galaxy Tab S2 would be upgraded to Android 6.0 in May 2016. The Galaxy Alpha would be updated to the latest Android software in June 2016.

After the Android 6.0 Marshmallow update is made available for flagship devices from Samsung, the software update would also be made available to other Galaxy devices. However, the publication has only mentioned that the Android 6.0 upgrade would be coming to Galaxy A7 (2016). It is likely that other A series smartphone from this year such as Galaxy A5 and A3 may receive the update later this year.

Samsung has recently launched the Galaxy S7 and S7 Edge smartphones. Both come preloaded with Android 6.0 Marshmallow OS that is customized with Samsung’s TouchWiz UI. Recent rumors suggest that the Galaxy S7 and Galaxy S7 Edge that were made available for presale from Feb. 23 are smashing preorder records in 60 launch markets across the world.

Electricity can flow through graphene at high frequencies without energy loss

Electrical signals transmitted at high frequencies lose none of their energy when passed through the 'wonder material' graphene, a study has shown. Discovered in 2004, graphene -- which measures just an atom in thickness and is around 100 times stronger than steel -- has been identified as having a range of potential uses across the engineering and health sectors.

Electrical signals transmitted at high frequencies lose none of their energy when passed through the 'wonder material' graphene, a study led by Plymouth University has shown.

Discovered in 2004, graphene -- which measures just an atom in thickness and is around 100 times stronger than steel -- has been identified as having a range of potential uses across the engineering and health sectors.

Now research has shown graphene out-performs any other known material, including superconductors, when carrying high-frequency electrical signals compared to direct current, essentially transmitting signals without any additional energy loss.

And since graphene lacks band-gap, which allows electrical signals to be switched on and off using silicon in digital electronics, academics say it seems most applicable for applications ranging from next generation high-speed transistors and amplifiers for mobile phones and satellite communications to ultra-sensitive biological sensors.

The study was led by Dr Shakil Awan, a Lecturer in the School of Computing, Electronics and Mathematics at Plymouth University, alongside colleagues from Cambridge and Tohoku (Japan) Universities and Nokia Technologies (Cambridge, UK).

Dr Shakil Awan, Lecturer in the School of Computing, Electronics and Mathematics and the principal investigator in the study, said: "An accurate understanding of the electromagnetic properties of graphene over a broad range of frequencies (from direct current to over 10 GHz) has been an important quest for several groups around the world. Initial measurements gave conflicting results with theory because graphene's intrinsic properties are often masked by much larger interfering signals from the supporting substrate, metallic contacts and measurement probes. Our results for the first time not only confirm the theoretical properties of graphene but also open up many new applications of the material in high-speed electronics and bio-sensing."

The study, published in the IOP 2D Materials Journal, was funded by the EU Graphene Flagship, EPSRC, ERC and Nokia Technologies, and the results are now being exploited in developing high-speed and efficient low noise amplifiers, mixers, radiation detectors and novel bio-sensors.

The latter is the focus of a three-year £1million project funded by the EPSRC on developing highly-sensitive graphene bio-sensors for early detection of dementia (such as Alzheimer's disease) compared to current methods.

Graphene is ideally suited for this as its room temperature thermal noise is smaller than any other known material, enabling the sensitive detection of tiny numbers of antibody-antigen interactions to indicate the likelihood of a patient to develop dementia in the future.

Dr Alan Colli, from Nokia Technologies, said: "Graphene devices for next generation wireless technologies (up to and beyond 10 GHz) are progressing fast. Our study has unlocked the fundamental behaviour of graphene at high frequencies, which will be essential in the design and evaluation of future graphene-based wireless devices. This has only been made possible because of the multi-discipline expertise of the different groups based at Nokia, and in Plymouth, Cambridge and Tohoku universities."