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Evidence of second fast northsouth pole flip found

first_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: Evidence of second fast north-south pole flip found (2010, September 6) retrieved 18 August 2019 from https://phys.org/news/2010-09-evidence-fast-north-south-pole-flip.html (PhysOrg.com) — The Earth’s magnetic poles flip around every 200,000 years or so, with north becoming south and vice versa. Normally, the process takes 4-5,000 years and it ought to be impossible for the flip to be much faster, if models of the Earth’s core are correct, but now for the second time evidence has been found of a flip that appears to have taken only a few years. The first time evidence was discovered of a rapid geomagnetic field reversal was in 1995 when well-preserved lava flows were found at Steens Mountain in Oregon in the US. Research on the rocks by a team led by geologist Scott Bogue of the Occidental College in Los Angeles revealed the lava flow had an unusual magnetic pattern that suggested the magnetic field had been shifting over 10,000 times faster than normal, at six degrees a day. The magnetic patterns are preserved within the magnetic crystals in the lava, formed as the lava flow cooled.The first findings remained controversial and many scientists have challenged the fast flip-flop theory, but now Bogue and colleague Jonathan Glen of the US Geological Survey have found evidence in ancient lava rock in Battle Mountain, Nevada of a second fast flip, dated around 15 million years ago.The record in one particular lava flow in Nevada suggests the magnetic field moved by 53 degrees in a single year. The lava started to cool, but was then heated again within a year as it was buried under fresh lava. The crystals in the rock were re-magnetized by the fresh lava, producing a shift of 53 degrees. This finding could mean the poles swapped over a period of only four years, but Brogue said it could also suggest there was a rapid acceleration period within the steady movement of the field.According to some geologists a polarity reversal is overdue, since the Earth’s magnetic field has been weakening for the last century, and the last stable reversal was about 780,000 years ago. Even if it was a super-fast flip-flop, however, it would not be noticeable to most people. No one is certain why such reversals take place, although many scientists believe they are connected in some way with the convective movements of the liquid iron in the Earth’s outer core.The findings are due to appear in Geophysical Research Letters. This wide angle view of the Earth is centered on the Atlantic Ocean between South America and Africa. Lava flows reveal clues to magnetic field reversals © 2010 PhysOrg.com More information: Bogue, S. W et al., Very rapid geomagnetic field change recorded by the partial remagnetization of a lava flow, Geophysical Research Letters, doi:10.1029/2010GL044286 , in press. Explore furtherlast_img read more

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Design student creates GAUNTLET glove that allows single handed typing w Video

first_img Citation: Design student creates G.A.U.N.T.L.E.T. glove that allows single handed typing (w/ Video) (2012, July 17) retrieved 18 August 2019 from https://phys.org/news/2012-07-student-gauntlet-glove-video.html (Phys.org) — Jiake Liu, co-founder of Kabob.it has been demonstrating his G.A.U.N.T.L.E.T. glove at this year’s TechCrunch meetup in Atlanta. The name of the glove is an acronym meant to describe both its function and looks. It has metallic letters affixed to parts of the front of the fingers and another metal piece on the thumb that allows for connections to be made when pressing the thumb against the letters, effectively allowing a person to use the glove as a Bluetooth enabled wireless keyboard that works with just one hand. Glove designers plan messaging path for deaf-blind The keyboard/glove is just one of many devices currently under development by researchers around the world to respond to the difficulties users have faced when trying to type on small smartphone screens or even on iPads. Though there are several Bluetooth enabled standard keyboards available for purchase, using them requires that they be toted around, a bulky proposition to be sure. Thus the search is on to find a way to allow users to type on their handheld devices in a reasonably elegant way.Liu told John Biggs of TechCrunch that he came up with the idea for his glove while still attending the University of Alabama in Huntsville as a senior design project after being inspired by some of the technology in such movies as Minority Report and has been tinkering with the idea ever since. He’s now a co-partner of Kabob.it a company that makes smart menus for people with food allergies to help them figure out which foods in restaurants are safe to eat. That venture has allowed him the funds to pursue the glove technology that he believes some people are looking for.The letters on the glove are arranged so that the most used letters are the easiest to reach; it also has an Enter key, spacebar and other function keys that allow the wearer to switch between keymaps, e.g. letters, numbers or special characters. It also has an accelerometer to allow for adjusting controls.The glove is not yet ready to be sold to consumers as Liu believes there is more work to be done to improve both the typing functionality and the overall look of the gloves, which clearly needs some work as it does still look like a work in progress. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.center_img © 2012 Phys.org Explore further More information: gauntletkeyboard.com/last_img read more

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Study finds semiclassical gravity counterintuitive but on the horizon of testability

first_img More information: Huan Yang, et al. “Macroscopic Quantum Mechanics in a Classical Spacetime.” PRL 110, 170401 (2013). DOI: 10.1103/PhysRevLett.110.170401 Citation: Study finds semiclassical gravity counterintuitive, but on the horizon of testability (2013, May 8) retrieved 18 August 2019 from https://phys.org/news/2013-05-semiclassical-gravity-counterintuitive-horizon-testability.html The physicists, Huan Yang, et al., at the California Institute of Technology in Pasadena, California, and the National Dong Hwa University in Hua-Lien, Taiwan, have published their paper, called “Macroscopic Quantum Mechanics in a Classical Spacetime,” in a recent issue of Physical Review Letters.Most theories of quantum gravity predict that gravity should be quantized. However, as Richard Feynman once said, “Quantum theory does not absolutely guarantee that gravity has to be quantized. … I would like to suggest that it is possible that quantum mechanics fails at large distances and for larger objects.” Since concrete, unambiguous experimental signatures of the quantum nature of gravity still do not exist (other than when assuming the “many-world” interpretation of quantum mechanics), the physicists here thought it would be worthwhile to investigate if a theory of quantum gravity could involve classical gravity.”Semiclassical gravity is one of the existing models which tries to unify quantum mechanics and general relativity,” Yang told Phys.org on behalf of his coauthors. “Instead of trying to quantize space and time (as in string theory, loop quantum gravity, etc.), in this model the spacetime is assumed to be a classical entity, although the matter particles in the spacetime are quantum. Our findings show the imminent possibility of verifying or falsifying the semiclassical gravity experimentally. More importantly, we point out that both self-gravitational effects and quantum effects are important for macroscopic objects—the only regime accessible by table-top experiments so far. This opens up the possibility for testing other models that try to unify quantum mechanics and general relativity, as well: gravity decoherence models, stochastic gravity models, emergent gravity models, etc. We don’t necessarily believe any of these models, but we believe it is important to test signatures/predictions of these models experimentally and let nature tell us what the true physics is, as we don’t have a conclusive theory of quantum gravity yet.” Physicists propose test for loop quantum gravity (Phys.org) —One of the more controversial theories of quantum gravity, which attempts to unify quantum mechanics and general relativity, is semiclassical gravity, which was proposed in the 1960s. As its name suggests, semiclassical gravity involves a combination of quantum and classical components. Specifically, matter obeys the rules of quantum mechanics while gravity and the spacetime structure obey classical laws. Many physicists think that integrating quantum and classical systems in this way creates physical contradictions and mathematical inconsistencies. However, in a new paper, physicists have closely analyzed exactly how classical gravity might affect the quantum properties of macroscopic objects, and found that the effects of semiclassical gravity may be experimentally detectable with state-of-the-art technology. Combining gravity and quantum mechanicsIn their paper, the scientists used a non-relativistic version of a semi-classical gravity model, which describes how the quantum state of a system changes over time under the influence of classical gravity, called the Schrödinger-Newton (SN) equation.Although physicists have extensively used the SN equation to study the quantum states of single particles, in the new paper the physicists use the equation to study the quantum states of macroscopic objects consisting of many particles. They show that the SN equation can be used to describe the quantum evolution of a macroscopic crystal’s center of mass, the point at which the object’s weight is perfectly balanced. The center-of-mass gives information on the self-gravitational effect that depends on the object’s internal structure, which enables physicists to investigate how the object’s quantum properties may be affected by classical gravity.The physicists’ calculations revealed several unique signatures of classical gravity on macroscopic quantum mechanics. Most interestingly, they found that the center-of-mass motion of a crystal is found to deviate slightly from standard quantum mechanics, obeying the SN equation where the center-of-mass wave function evolves nonlinearly due to self-gravitating effects.The calculations also revealed other interesting insights. For instance, the classical gravity of a single macroscopic crystal is much stronger in relation to itself than it is between two separate crystals. The physicists explain that this effect arises because the mass of a macroscopic crystal is concentrated near its lattice sites. Another signature of classical gravity acting on macroscopic quantum objects is that classical gravity cannot be used to transfer quantum uncertainties between two objects. In addition, the scientists discovered a unique signature regarding the evolution frequency of expectation values of position and momentum.Searching for semiclassical signaturesAlthough these effects are extremely weak, the physicists predict that one or more effects may induce visible signatures that are detectable with state-of-the-art optomechanics experiments. This kind of experiment could monitor and manipulate a macroscopic object’s center-of-mass at quantum levels. Although the individual particles in a macroscopic object cannot be accessed separately, a light beam could probe the average displacement of the atoms in the first few layers of a reflective coating on a macroscopic object. Since the motion of these surface atoms is related to the center-of-mass motion of the entire object, the experiment could potentially probe some of the unique effects hinting at semiclassical gravity.”If the future experiment sees the effects predicted by the SN equation, this means gravity/spacetime is classical, and previous attempts for quantizing gravity were on the wrong track, which is unlikely but nevertheless possible,” Yang said. “However, if the experiment shows null results, it is highly possible that gravity is quantum. The third possibility is that the experiment sees some non-null result which is not consistent with SN prediction either. This may inspire physicists to formulate new theories of quantum gravity, given the experimental results.”Overall, the results show that semiclassical gravity involves effects that are counterintuitive, but not necessarily contradictory. Although experimentally detecting such effects is unlikely, their detection would open up many new opportunities in the search for quantum gravity. “We talked to several experimental groups, including Nergis Mavalvala’s group at MIT, Thomas Corbitt’s group at Louisiana State Universiity, Markus Aspelmeyer’s group at the University of Vienna, and Michael Tobar’s group at Western Australia University,” Yang said. “They were very excited about the idea and the possibility of doing the experiment. We will collaborate with experimentalists in performing such an experiment in the future.”center_img © 2013 Phys.org. All rights reserved. Journal information: Physical Review Letters This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Explore furtherlast_img read more

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Water ice detected at the surface of a distant stars disk

first_img © 2016 Phys.org Astronomers peer into the ‘amniotic sac’ of a planet-hosting star HD 100546 is a 10 million-year-old star located some 320 light years from the Earth. It is accompanied by a fairly flat circumstellar disk in an advanced evolutionary state residing at a distance of 0.2 to four AU, and again from 13 to a few hundred AU from the star. The Hubble Space Telescope revealed that the disk features some complex spiral patterns. However, the nature and origin of these patterns remains uncertain.The star was observed using NICI on Mar. 31, 2012. This instrument is a coronagraphic camera designed to survey for and image large, extra-solar gaseous planets. It allows astronomers to search for large Jupiter planets around nearby stars by spectrally differencing two images taken in or next to strong, near-infrared methane features found in the atmosphere of large, Jovian-type planets.The scientists extracted the scattered light spectra of different regions of the protoplanetary disk around HD 100546. Scattered light observations complement thermal observations and constrain models based on spectroscopic data. NICI helped them unveil the 3.1 µm absorption feature in the scattered light spectrum of the observed disk. They link this feature with the presence of water ice grains.According to the research team, the shallowness of this ice absorption feature can be explained by the loss of ice grains at the disk surface.”In almost all the regions, relatively shallow three µm absorption feature is present in their spectra likely due to water ice grains, indicating that the water ice grains present in the disk surface,” the paper reads.Previous studies claimed that the water ice grains can be quickly destroyed at the disk surface around stars like HD 100546 due to a strong ultraviolet photodesorption.The discovery made by Honda and colleagues could provide new insights on planet formation theories as water ice is believed to play many important roles in the process of forming planetesimals. For instance, ice enhances the surface density of solid material in the cold outer part of a protoplanetary disk, which promotes the formation of massive cores of gaseous planets.”The ice sublimation/condensation front called snowline is considered to be the boundary of the forming regions of the terrestrial and Jovian planets. Snowline is also suggested as a possible forming site of the planetesimals,” the researchers wrote in the paper.The astronomers noted that in order to comprehensively understand the water ice distribution in the protoplanetary disks, other effects on the depth of water ice absorption should be investigated in future theoretical studies. They suggest that further investigations should focus on the grain size, shape and its structure, as well as ice/rock ratio (abundance), dust settling, turbulent mixing, and so on.”Further observations with better photometric accuracy are strongly desired,” the scientists concluded. Citation: Water ice detected at the surface of a distant star’s disk (2016, April 7) retrieved 18 August 2019 from https://phys.org/news/2016-04-ice-surface-distant-star-disk.html More information: Water ice at the surface of HD 100546 disk, arXiv:1603.09512 [astro-ph.EP] arxiv.org/abs/1603.09512AbstractWe made near infrared multicolor imaging observations of a disk around Herbig Be star HD100546 using Gemini/NICI. K (2.2,μm), H2O ice (3.06,μm), and L'(3.8,μm) disk images were obtained and we found the 3.1,μm absorption feature in the scattered light spectrum, likely due to water ice grains at the disk surface. We compared the observed depth of the ice absorption feature with the disk model based on cite{Oka2012} including water ice photodesorption effect by stellar UV photons. The observed absorption depth can be explained by the both disk models with/without photodesorption effect within the measurement accuracy, but slightly favors the model with photodesorption effects, implying that the UV photons play an important role on the survival/destruction of ice grains at the Herbig Ae/Be disk surface. Further improvement on the accuracy of the observations of the water ice absorption depth is needed to constrain the disk models. Explore further This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. (Phys.org)—A team of Japanese astronomers has recently discovered water ice at the surface of a distant star’s disk. Using the Near-Infrared Coronagraphic Imager (NICI) installed on the Gemini South Telescope in Chile, the researchers, led by Mitsuhiko Honda at the Kurume University School of Medicine’s Department of Physics, found that a circumstellar disk around the star HD 100546 contains water ice grains. The findings are reported in a paper published online on Mar. 31 in the arXiv repository. Positions of the spectra extracted region shown in the L’ image of HD100546 disk. A 0.162′′ square regions were set along the major (SE-NW) and minor (SW-NE) axis of the disk at the position of 0.360′′, 0.522′′, 0.684′′, 0.846′′, and 1.008′′ from the central star. Credit: Honda et al., 2016.last_img read more

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Algorithm ensures that random numbers are truly random

first_img Citation: Algorithm ensures that random numbers are truly random (2016, June 24) retrieved 18 August 2019 from https://phys.org/news/2016-06-algorithm-random.html (Phys.org)—Generating a sequence of random numbers may be more difficult than it sounds. Although the numbers may appear random, how do you know for sure that they don’t actually follow some complex, underlying pattern? For this reason, finding a way to certify that a sequence of numbers is truly random is often more challenging than generating the sequence in the first place. In the new study, the researchers use the first method, by measuring the quantum states of some physical system. However, the physical method has its own problems: How do you know for sure that the measurement devices used to measure the physical system don’t have some underlying predictability due to the way they were constructed? To overcome this problem, scientists have developed strict requirements on the devices, but these “device-independent” protocols are so strict that they are very slow at generating large amounts of random numbers.As a compromise between security and efficiency, researchers have developed “semi-device-independent” protocols that don’t have such strict requirements, but do place limits on the device capacity. These protocols can generate truly random numbers, but they still require a large amount of post-processing computational power to certify that the sequences are random. More randomness with more computing powerIn the new paper, the researchers’ main contributions is showing that a tradeoff exists for semi-device-independent protocols. The more computational power that is available to analyze the experimental data and certify its randomness, the less strict the requirements need to be on the measurement devices that generate the random data in the first place.Based on this tradeoff, the researchers designed a new algorithm that can extract more data from the experiment, and then, using a large amount of computing power, can certify a large amount of randomness—more than any other method developed to date. Even more importantly, it can do so faster and even work in cases where slower methods don’t work at all.”Our method allows to certify more randomness than the standard one,” Pawłowski said. “Let’s assume that you are using the latter and get 1 bit/second and using ours you get 2 bits/second. It means that the same device certified with our method need half the time to produce the required mount of bits. It’s nice. “But there are cases when our method certifies 1 bit/sec and the standard one 0. Now our method becomes really important because without it we have a completely useless device. I think this is its biggest advantage—making useless devices useful.”The new method also has the advantage that it doesn’t require altering the physical quantum system like other methods do, although it does come at the cost of requiring greater computing power. Nevertheless, the researchers believe that this is a worthwhile tradeoff, and expect that the new approach will guide future research on random number certification.”We have demonstrated the usefulness of our method in one case, but we have preliminary results and hand-weaving arguments that suggest that our method may be applied for different experimental setups and scenarios (for example, fully device-independent or with one party fully trusted),” Pawłowski said. “We are now trying to prove this and see in which situations it is most useful. Our second goal is to try to reduce the time of computation required for certifying more randomness. We have some preliminary results here too, which suggest it can be done.” New method of producing random numbers could improve cybersecurity Explore further Researchers have developed a method to certify more randomness in long sequences of random numbers than other methods can. Credit: Mironowicz et al. CC-BY-3.0 More information: Piotr Mironowicz et al. “Increased certification of semi-device independent random numbers using many inputs and more post-processing.” New Journal of Physics. DOI: 10.1088/1367-2630/18/6/065004 Journal information: New Journal of Physics © 2016 Phys.org. All rights reserved. In a new study, researchers have developed a new algorithm that increases the amount of certified randomness in a sequence of seemingly random numbers that has been generated experimentally. The researchers, Piotr Mironowicz et al., at universities in Poland, Sweden, and Brazil, have published their paper on the new random number certification algorithm in a recent issue of the New Journal of Physics.As the scientists explain, generating long sequences of numbers with certified randomness is critical for ensuring security in computers, cell phones, and other electronic devices.”Every electronic device needs randomness and needs a lot of it,” coauthor Marcin Pawłowski at the University of Gdańsk in Poland told Phys.org. “Randomness is necessary whenever you need security. Whenever you want secure communication, a cryptographic key must be generated. It has to be generated randomly so that no adversary can easily guess it. Nowadays, every communication is encrypted that way. Whenever you call someone on your mobile phone or send a text, a sequence of random numbers has to be generated. If someone can predict these numbers (it doesn’t have to be perfect—if he or she can guess some of them it’s enough), they can listen to your conversation. “Random numbers are constantly being generated by every machine that can communicate. And even if it does not communicate, every computer needs randomness to allocate programs in the memory. It is trivial to hack a computer which assigns the same place in its memory for the same program every time it’s run. Exploiting backdoors or malfunctions in random number generators is one of the most common ways to attack communication or computer systems.” Lots of numbers, no patternAlthough it’s relatively easy to generate and certify short sequences of random numbers, cryptographic applications require long sequences of random numbers, and the length is what makes the task much more challenging.In general, researchers use two main methods to generate long sequences of random numbers. The first method is based on exploiting the randomness inherent in physical systems, such as the optical noise in lasers and radioactive decay in atoms. This randomness can be traced back to these systems’ quantum properties. The second method uses computer software that can perform complicated arithmetical procedures. Technically, only the first method produces truly random numbers. The computer-generated numbers are considered “pseudorandom” because knowing how the program develops its computations makes it possible to predict these numbers, which only appear random. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

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Irregular dimming of a young stellar object investigated by astronomers

first_img(Phys.org)—New research conducted by a team of astronomers, led by Simone Scaringi of the Max Planck Institute for Extraterrestrial Physics in Germany, examines peculiar dimming of a newly found young stellar object designated EPIC 204278916. The study tries to explain the nature of these dipping events observed in the object’s light curve. The results were published Aug. 25 in a paper available on arXiv.org. Astronomers discover a giant inflated exoplanet orbiting a distant star Explore further This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. More information: The peculiar dipping events in the disk-bearing young-stellar object EPIC 204278916, arXiv:1608.07291 [astro-ph.SR] arxiv.org/abs/1608.07291AbstractEPIC 204278916 has been serendipitously discovered from its K2 light curve which displays irregular dimmings of up to 65% for ~25 consecutive days out of 78.8 days of observations. For the remaining duration of the observations, the variability is highly periodic and attributed to stellar rotation. The star is a young, low-mass (M-type) pre-main-sequence star with clear evidence of a resolved tilted disk from ALMA observations. We examine the K2 light curve in detail and hypothesise that the irregular dimmings are caused by either a warped inner-disk edge or transiting cometary-like objects in either circular or eccentric orbits. The explanations discussed here are particularly relevant for other recently discovered young objects with similar absorption dips. EPIC 204278916 light curve. The system was observed for over 78.8 days at 29.4 minute cadence. The units on the y-axis are electrons/second, and can be converted to Kepler magnitudes Kp using the conversion found in the Kepler Instrument Handbook. The top panel shows the full light curve, whilst the bottom panel zooms into the first 25 days of observation where the dipping events are observed. Credit: Scaringi et al., 2016. © 2016 Phys.org EPIC 204278916, is a young, pre-main-sequence star, about 5 million years old, of spectral type M1, located in the Upper Scorpius sub-group of the Scorpius-Centaurus OB association. It is the size of our sun in diameter, but has only 0.5 solar masses. This young stellar object was discovered by NASA Kepler spacecraft’s prolonged mission known as K2, during its Campaign 2 between Aug. 23 and Nov. 13, 2014. Moreover, follow-up observations made with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile revealed that EPIC 204278916 also has a resolved tilted disk.In a recent paper, Scaringi and his colleagues analyze the data provided by K2 and ALMA regarding EPIC 204278916, available in the Ecliptic Plane Input Catalog (EPIC) and the Mikulski Archive for Space Telescope (MAST) archive, with the aim to examine the object’s light curve and its irregular dimmings in detail.”We examine the K2 light curve in detail and hypothesize that the irregular dimmings are caused by either a warped inner-disk edge or transiting cometary-like objects in either circular or eccentric orbits,” the researchers wrote in the paper.According to the data provided by K2, EPIC 204278916 exhibited irregular dimmings of up to 65 percent for about 25 consecutive days out of 79 days of observations. The researchers also noted that when it comes to the remaining days of observation, this variability is highly periodic and could be attributed to stellar rotation.One of the two most plausible explanations offered by the astronomers to explain the irregular dips in the object’s light curve is that they are caused by non-axisymmetric structures in the inner disk edge occulting EPIC 204278916. Due to the fact that these dimmings are at a level of up to 65 percent, the occulting material must have a large scale height comparable to the size of the object.The researchers also noted that the dips in young stellar objects like EPIC 204278916 might be caused by transiting circumstellar objects. They emphasized that if transiting cometary-like bodies are responsible for the observed dips, the events are most likely occurring close to periastron passage.However, more observations are definitely needed to fully understand the mysterious behavior of EPIC 204278916. Moreover, further continuous photometric and spectroscopic monitoring of this system for subsequent dipping events will help determine whether this behavior is periodic or not.”It is clear that further observations of EPIC 204278916 and other young stellar object dippers will be required in the future, both photometric and spectroscopic, in order to establish their true origin. In particular, it is important to determine whether the observed dips in the K2 light curve of EPIC 204278916 are observed again, in which case infer their recurrence timescale and spectroscopic properties,” the team concluded.The researchers could soon get the opportunity to revisit EPIC 204278916, as in 2017 the K2 mission could re-observe the Scorpius-Centaurus OB association during the planned Campaign 15. Citation: Irregular dimming of a young stellar object investigated by astronomers (2016, August 30) retrieved 18 August 2019 from https://phys.org/news/2016-08-irregular-dimming-young-stellar-astronomers.htmllast_img read more

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Are Rossby waves to blame for Earths magnetic field drifting westward

first_imgSchematic of the control volume considered when deriving the governing equation for a QG flow. Credit: Proceedings of the Royal Society A: Mathematical, Physical and Engineering Science (2018). DOI: 10.1098/rspa.2018.0119 Journal information: Proceedings of the Royal Society A © 2018 Phys.org Citation: Are Rossby waves to blame for Earth’s magnetic field drifting westward? (2018, May 16) retrieved 18 August 2019 from https://phys.org/news/2018-05-rossby-blame-earth-magnetic-field.html A doctoral student at the University of Cambridge has come up with a possible explanation for the westward drift of the Earth’s magnetic field. In his paper published in Proceedings of the Royal Society A, O.P. Bardsley suggests it may be due to Rossby waves generated in the Earth’s core. Waves similar to those controlling weather on Earth have now been found on the Suncenter_img Humans first became aware of the Earth’s magnetic field over 400 years ago, and since that time, have been taking measurements of it. As time passed, it became clear that the field was moving in a westerly direction—and nobody knew why. The actual reason is still not known—Bardsley is proposing a new idea: Somehow, Rossby waves in the Earth’s outer core cause the magnetic drift.Prior efforts to explain the westward drift have also involved the outer core—one theory suggests that it has a gyre, similar in some respects to the jet stream. If so, it could be dragging the magnetic field as it moves slowly westward. The problem with that theory, Bardsley notes, is that no one has ever found any other evidence of a gyre in the outer core. He suggests Rossby waves make more sense.Rossby waves are slow and arise when fluids rotate. Because they are generated by most planets, some scientists have taken to calling them planetary waves. Rossby waves on Earth are generated in several places—in the oceans, the atmosphere and the outer core. It is those generated by the fluid in the outer core that Bardsley suggests might be pushing the magnetic field. But there is one major problem: The outer core generates wave crests that move east, not west. Bardsley suggests that this may not be a problem after all—he notes that some ocean waves with crests moving in one direction expend energy in the opposite direction. If that is the case with outer core Rossby waves, he suggests, they could be pushing the magnetic field. He notes that current technology only allows for measuring the energy of the magnetic field in a general sense, not the small details. Much more research is required, he acknowledges, before his theory can be tested, much less proven right or wrong. Explore further This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. More information: O. P. Bardsley. Could hydrodynamic Rossby waves explain the westward drift?, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Science (2018). DOI: 10.1098/rspa.2018.0119AbstractA novel theory for the origin of the westward drift of the Earth’s magnetic field is proposed, based upon the propagation of hydrodynamic Rossby waves in the liquid outer core. These waves have the obscure property that their crests always progress eastwards—but, for a certain subset, energy can nevertheless be transmitted westwards. In fact, this subset corresponds to sheet-like flow structures, extended in both the axial and radial directions, which are likely to be preferentially excited by convective upwellings in the Earth’s rapidly rotating outer core. To enable their analysis, the quasi-geostrophic (QG) approximation is employed, which assumes horizontal motions to be independent of distance along the rotation axis, yet accounts for variations in the container height (i.e. the slope of the core–mantle boundary). By projecting the momentum equation onto flows of a QG form, a general equation governing their evolution is derived, which is then adapted for the treatment of two initial value problems—in both Cartesian and spherical geometries—which demonstrate the preference for westward energy propagation by the waves in question. The merits of this mechanism as an explanation for westward drift are discussed.last_img read more

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Highresolution observations uncover detailed structure of blazars jet

first_imgUsing Russia’s Spektr-R space telescope (also known as RadioAstron), astronomers have conducted high-resolution observations of the blazar S5 0716+71. The results of these observations, presented in a paper published February 12 on the arXiv pre-print server, provide insights into the structure of the blazar’s jet. More information: E. V. Kravchenko et al. The jet of S5 0716+71 at μas scales with RadioAstron. arXiv:1902.04369 [astro-ph.GA]. arxiv.org/abs/1902.04369 Citation: High-resolution observations uncover detailed structure of blazar’s jet (2019, February 25) retrieved 18 August 2019 from https://phys.org/news/2019-02-high-resolution-uncover-blazar-jet.html Explore further © 2019 Science X Network Luminous gamma-ray flare detected from the blazar DA 193 (uv)-coverage (left) and polarimetric RadioAstron image of 0716+714 (right) made on January 3-4, 2015 at 22 GHz, using uniform weighting. Credit: Kravchenko et al., 2019. Blazars, classified as members of a larger group of active galaxies that host active galactic nuclei (AGN), are powerful sources of emission across the electromagnetic spectrum from radio to very high-energy gamma frequencies. Their characteristic features are relativistic jets pointed almost exactly toward the Earth.In general, blazars are perceived by astronomers as high-energy engines serving as natural laboratories to study particle acceleration, relativistic plasma processes, magnetic field dynamics and black hole physics. Therefore, high-resolution observations of blazars and their jets in different wavelengths could be essential for improving the understanding of these phenomena. BL Lacertae objects (BL Lacs) are a type of blazar showcasing lower-power jets and higher Doppler factors than other blazars. S5 0716+71 is one of BL Lacs known for its extreme variability across the electromagnetic spectrum, including the so-called intraday variability (IDV). While the IDV phenomenon still baffles scientists, there is evidence that it is being produced by processes intrinsic to the relativistic jet. S5 0716+71 is currently one of the best candidates for having an intrinsic origin of the observed IDV. Hence, a team of astronomers led by Evgeniya V. Kravchenko of Astro Space Center of Lebedev Physical Institute, Russia, decided to use Spektr-R to investigate S5 0716+71’s jet structure at the finest angular resolution and to investigate the origin of its IDV.”Here, we report on RadioAstron observations of the BL Lac object S5 0716+71, performed in a framework of the AGN Polarization and Survey Key Science Programs at 22 GHz during 2012-2018. We obtained the highest angular resolution image of the source to date, at 57×24 μas,” the astronomers wrote in the paper.Spektr-R’s 10-m radio telescope (SRT), with angular resolution of about 7.0 microarcseconds (μas) at 1.3 cm, allowed Kravchenko’s team to find essential information about S5 0716+71, especially regarding the structure of its jet.The observations revealed a complex bent structure in the central 100 μas core region, consisting of an unresolved core and two nearby components, designated C1 and C2, located at approximately 41 μas and 58 μas from the core respectively. The size of the core was estimated to be not greater than 60 μas, while C1 and C2 have sizes of around 32 and 19 μas respectively.According to the paper, S5 0716+71’s jet initially extends towards the south-east, at a position angle of 153 degrees, followed by a sharp bending of about 95 degrees towards the north-east. The jet maintains that direction for about one milliarcsecond (mas) until another sharp bend towards the north-west is observed on the images provided by SRT.The researchers detected linear polarization in the core and jet areas at the projected baselines up to about 5.6 Earth diameters. They also obtained the observed brightness temperatures in the rest frame of the source, which turned out to be greater than 22 trillion K for the core, at a level of about 699 billion K for C1, and around 1.2 trillion for C2.In concluding remarks, the astronomers underlined that in the case of S5 0716+71 the intrinsic processes in jet can explain its variability on the time scales of a days to week. They added that their study confirms Spektr-R’s powerful capabilities to investigate relativistic jets in the vicinity of central black holes. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

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Tata Steel Q2 profit firms up by 37

first_imgTata Steel on Wednesday reported 37 per cent rise in consolidated net profit to Rs 1,254.33 crore for the July-September quarter mainly on account of proceeds from land sale worth Rs 1,146.86 crore.The world’s 11th biggest steelmaker had clocked Rs 916.77 crore net profit in the corresponding quarter of the last fiscal, it said in a statement. The profit of the company before exceptional item and tax stood at Rs 1,302 crore, from Rs 1,398 crore.Tata Steel’s total income declined to Rs 35,777 crore in the second quarter of 2014-15, from Rs 36,645 crore a year earlier. Its expenses also fell to Rs 33,564 crore from Rs 34,384 crore a year earlier.Total tax expenses of the company, however, rose to Rs 1,175 crore from Rs 447 crore a year earlier.last_img

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NPPA warns drug cos on nonregistration with online database

first_imgWith just 41 out of top 100 pharma firms responding to its direction to register for online database, drug price regulator NPPA has warned to take action if the rest of the companies did not comply with its order immediately.National Pharmaceutical Pricing Authority (NPPA) had asked all pharma firms to register themselves with Integrated Pharmaceutical Database Management System (IPDMS) in September last year. “Many pharma companies have yet not registered with IPDMS despite extension of time limit by NPPA. It has been observed that out of top 100 pharma companies, 59 companies have not registered with the system,” NPPA said in a notice to pharma industry bodies on its website. Also Read – I-T issues 17-point checklist to trace unaccounted DeMO cashThe list of 59 companies which have not registered include Zydus Cadila, Dr Reddys Labs, IPCA labs and Biocon, among others. Stating that it would be launching the system shortly, NPPA said: “You are therefore requested to impress among your member companies to register themselves with IPDMS immediately, failing which NPPA shall be constrained to take appropriate action…” In September last year, national drug pricing regulator NPPA had asked all pharmaceutical firms to register themselves under the IPDMS for online filing of returns for monitoring, fixing and revision of drug prices.It had said that availability of reliable database is a necessary pre-requisite for carrying out the functions of price fixation and price revision in respect of scheduled drugs and price fixation in respect of new drugs.last_img read more

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