New ultracapacitor recharges in under a millisecond

first_img © 2010 More information: John R. Miller et al., Graphene Double-Layer Capacitor with ac Line-Filtering Performance, Science 24 September 2010: Vol. 329. no. 5999, pp. 1637 – 1639. DOI:10.1126/science.1194372 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. ( — A new ultracapacitor or electric double-layer capacitor (DLC) design has been announced in the journal Science this week, and could pave the way for smaller and lighter portable electronics devices. Ultracapacitors Make City Buses Cheaper, Greener Explore further (A) Plan SEM micrograph of coated Ni electrode. (B) SEM micrograph of a coated fiber, showing plan and shallow-angle views. Image credit: Science, DOI:10.1126/science.1194372 Citation: New ultracapacitor recharges in under a millisecond (2010, September 24) retrieved 18 August 2019 from Ultracapacitors are capable of charging and discharging in only seconds and this gives them an advantage over batteries, which take much longer, and make them extremely useful in applications such as regenerative braking. However, for some applications even a few seconds is too long, and this is where a new nanoscale ultracapacitor comes in. Researchers in the US have built an ultracapacitor from nanometer-scale fins of graphene, and this design gives them a device that can charge/discharge in under 200 microseconds. Ultracapacitors store charge in electric fields between conducting surfaces, so a larger surface area of conducting surfaces enables the device to hold more charge. A larger amount of stored charge enables ultracapacitors to work in devices needing more energy than ordinary capacitors can provide, and they can deliver the energy much faster than a battery.A team of researchers led by John Miller, president of JME, an electrochemical capacitor company based in Shaker Heights, Ohio has been able to increase the speed of the ultracapacitor by redesigning the electrodes to give more surface area. The new electrode, developed by Ron Outlaw, a team member from the College of William and Mary, in Williamsburg, Virginia, consists of sheets of graphene sticking up vertically from a graphite base. The graphene sheets are made of carbon one atom thick, and grown by a plasma-assisted chemical vapor deposition process. The graphite base is 10 nanometers thick. Miller described the design as resembling “rows of 600-nanometer tall potato chips standing on edge.”The design allows for much faster charging and recharging than stacked graphene sheets used in earlier ultracapacitors or the pored surfaces of activated carbon ultracapacitors.According to Miller’s team, the new ultracapacitor could replace bulky capacitors in portable devices to free up more space while still smoothing out peaks and troughs in power supplies. It has been tested in a filtering circuit in an AC rectifier, a task at which other ultracapacitors fail. (AC rectifiers tend to leave a voltage ripple that the capacitor smooths out.) Other ultracapacitors fail because their porous electrodes make them act like resistors in filter circuits. The new ultracapacitor worked well in the test, which means they could replace the current capacitors, which are six times larger. Ron Outlaw said work is continuing on increasing the capacitance and attempting to make the graphene sheets taller and more parallel with the aim of finding the perfect balance of maximum charge storage with minimum restriction of ion flow in the electrolyte. As size and weight of the ultracapacitors are reduced, they will find more applications in areas such as airlines, the military, and NASA.last_img read more

Windows 8 readies pushbutton PC refresh reset

first_imgResetting your Win 8 PC More information: … d-reset-your-pc.aspx Both functions will be at the push of a button to help users easily reset or refresh their PCs. “The power of personalization is something we all love about PCs,” said a Microsoft Steven Sinofsky,” but sometimes there is good reason to want to roll back to an earlier state. Most consumer electronics devices today can be reset to some factory state, and so we built this capability into Windows 8 too.” In the post authored by Desmond Lee, a Microsoft program manager, the new push-button options will empower the user to refresh or reset their machines. The latter function will be useful for those who want to give their machines to somebody else, such as a family member or coworker, and at the same time want to scrub everything off that they have downloaded. Hitting reset allows complete program and data wipeout and a fresh Windows install.As for the refresh function, Lee said that “misconfigured settings are sometimes the cause of problems that lead to customers needing to refresh their PCs. To ensure that Refresh is both effective in fixing problems and in making sure customers don’t lose settings that they might have trouble reconfiguring, we’ve thought a great deal about which settings to preserve.”In the refresh, Windows 8 is to preserve wireless network connections, mobile broadband connections, BitLocker and BitLocker To Go settings, Drive letter assignments, personalization settings such as lock screen background and desktop wallpaper. While the core settings are backed up, the refresh will not keep file-type associations, display settings, and Windows firewall settings.As for business environments, where Windows 8 might be deployed across the entire corporation’s PCs, a blogger outside Microsoft said that this does not necessarily spell out the demise of IT support; only that their troubleshooting rounds may be eased.In sum, the reset removes all personal data, apps, and settings from the PC and reinstall Windows. The refresh keeps all personal data, Metro style apps, and important settings from the PC, but reinstalls Windows. The time required doing a refresh or a reset is an estimated eight minutes and 22 seconds for a refresh and six minutes and 12 seconds for a quick reset. The Register notes that these numbers are based on a Samsung PC with an i5 processor and 4GB of RAM running the Windows 8 developer preview handed out at the Build Conference in September. A thorough reset takes 23 minutes and 52 seconds. The “thorough” option will write random patterns to every sector of the drive, overwriting existing data visible to the operating system. Microsoft gives further peek at Windows 8 © 2011 PhysOrg.comcenter_img ( — Windows 8 is to deliver two new features that could help mute a past history of being the company that delivers blue screens of death and malware magnets. Briefly, Windows 8 is going to make Windows easier to deal with than ever before. Considering the competition Microsoft now faces, the time is ripe for this kind of pronouncement. In a blog dated January 4, the Windows 8 engineering team reveals two new options, refresh and reset. Citation: Windows 8 readies push-button PC refresh, reset (2012, January 5) retrieved 18 August 2019 from 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.last_img read more

Spontaneous wave function collapse can suppress acoustic Schrodinger cat states

first_img © 2014 Citation: Spontaneous wave function collapse can suppress acoustic Schrodinger cat states (2014, October 28) retrieved 18 August 2019 from “Different people emphasize different concerns about Cats,” Lajos Diósi, a physicist the Wigner Research Center for Physics in Budapest, Hungary, told “Some people emphasize different ones at different times. So, allow me to pick up two arguments. Penrose (in my words): A Cat implies superposition of macroscopically different space-times, making physical time elusive. Myself: If we measure a Cat state a la von Neumann (why not?), then the collapse will macroscopically violate many conservation laws.”To address such problems, Diósi has expanded upon a model in which gravity-related spontaneous wave function collapses can suppress Schrödinger cat states, forcing them to take on only one value. Diósi’s paper on suppressing cat states is published in a recent issue of the New Journal of Physics.Several years ago, Diósi and Sir Roger Penrose each independently derived a model which can cause the spontaneous collapse of a cat state. This model came to be known as the DP model. According to the model, the measure of “catness” can be quantified as the difference between the two gravitational fields corresponding to the two states that make up a cat state. The greater the catness, the shorter the cat state’s decay time. Traditionally, the DP model is applied to single macroscopic degrees of freedom, such as the center of mass of a macroscopic object. In the new paper, Diósi has for the first time derived the DP model for the acoustic degree of freedom of a macroscopic object. Basically, he shows that macroscopic excitations, or sound waves, vibrating inside a macroscopic object such as a large rock will spontaneously decohere, meaning any acoustic cat states will collapse. The findings open up new perspectives on the concept of macroscopic superposition.”Spontaneous models are usually thought to influence bodies under extreme isolated conditions [at very cold temperatures],” Diósi said. “I discussed the possibility that the DP model might be significant in common phenomena. I don’t mean a directly testable effect in acoustic waves, I mean a first step toward a theoretical search for parametric regimes where spontaneous collapse acts in the common matter of a common state.” Micro-macro entangled ‘cat states’ could one day test quantum gravity Explore further Schrödinger’s cat: a cat, a flask of poison, and a radioactive source are placed in a sealed box. If an internal monitor detects radioactivity (i.e. a single atom decaying), the flask is shattered, releasing the poison that kills the cat. The Copenhagen interpretation of quantum mechanics implies that after a while, the cat is simultaneously alive and dead. Yet, when one looks in the box, one sees the cat either alive or dead, not both alive and dead. This poses the question of when exactly quantum superposition ends and reality collapses into one possibility or the other. Credit: Wikipedia / CC BY-SA 3.0center_img Journal information: New Journal of Physics ( —Schrödinger’s famous thought experiment in which a cat hidden in a box can be both dead and alive at the same time demonstrates the concept of superposition on the macroscopic scale. However, the existence of such “cat states” (or simply “Cats”) would be problematic in reality, as cat states not only go against common sense, but also pose problems for understanding gravity and spacetime. More information: Lajos Diósi. “Gravity-related spontaneous wave function collapse in bulk matter.” New Journal of Physics. DOI: 10.1088/1367-2630/16/10/105006 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

Study effort leads to estimates of number of tree species in tropics

first_img Inga spiralis are plants in the bean family (Fabaceae) is only found in Panama. Many areas in the tropics have still never been thoroughly explored by botanists. Credit: ourtesy of STRI/ Carmen Galdames Faster evolution not responsible for tropical biodiversity Citation: Study effort leads to estimates of number of tree species in tropics (2015, June 3) retrieved 18 August 2019 from The team also notes that the three main tropical regions far outpace other regions in tree diversity—North America, for example, they report has less than a thousand individual species, and the temperate forests in Europe have as few as 124. They also note that a large number of species in general does not equate to large numbers of individual members of a species—many of the species samples they found turned out to be quite rare, suggesting that many of them may be at risk. Explore further More information: An estimate of the number of tropical tree species, J. W. Ferry Slik, PNAS, DOI: 10.1073/pnas.1423147112 AbstractThe high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher’s alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼40,000 and ∼53,000, i.e., at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of ∼19,000–25,000 tree species. Continental Africa is relatively depauperate with a minimum of ∼4,500–6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa. Journal information: Proceedings of the National Academy of Sciencescenter_img © 2015 (—An unusually large team of researchers (over 140) from all walks of life have worked together to provide a new estimate on the total number of tree species in the three main tropical regions on planet Earth: the Americas (neotropics), Indo-Pacific and tropical parts of Africa. In outlining their findings in their paper published in Proceedings of the National Academy of Sciences, the team reports that assumptions about species diversity may have been over-generalized in the past. For many years, the general consensus has been that the Americas have the richest diversity of tree growth in the world, also estimates of such diversity have ranged from thirty-seven thousand to fifty thousand worldwide—the researchers with this new effort say both assumptions are wrong. They found that the number of species in the Indo-Pacific tropics was nearly equal to that of the Americas, and that species numbers are closer to forty to fifty thousand in total. The researchers conclude that their findings regarding species variety numbers in the Indo-Pacific tropics make sense when considering the geography, history and topography of places such as India, Southeast Asia, Madagascar, etc. They also noted that there appeared to be few species shared among the tropical regions.To come to these conclusions, the researchers collected data from a variety of sources, covering approximately 657,000 individual trees and over 11,000 species. More specifically, they found that tree species in the Americas and the Indo-Pacific tropics amounted to 19,000 to 25,000 each. Africa on the other hand had far fewer species, likely due, the team claims, to extinctions that have occurred since the Pleistocene and shrinkage of forests in general on the continent. Tropical forest in Martinique near the city of Fond St-Denis. Credit: Wikipedia 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

Graphene made superconductive by doping with lithium atoms

first_img More information: Evidence for superconductivity in Li-decorated monolayer graphene, arXiv:1508.05925 [cond-mat.supr-con] graphene exhibits many spectacular electronic properties, with superconductivity being arguably the most notable exception. It was theoretically proposed that superconductivity might be induced by enhancing the electron-phonon coupling through the decoration of graphene with an alkali adatom superlattice [Profeta et al. Nat. Phys. 8, 131-134 (2012)]. While experiments have indeed demonstrated an adatom-induced enhancement of the electron-phonon coupling, superconductivity has never been observed. Using angle-resolved photoemission spectroscopy (ARPES) we show that lithium deposited on graphene at low temperature strongly modifies the phonon density of states, leading to an enhancement of the electron-phonon coupling of up to λ≃0.58. On part of the graphene-derived π∗-band Fermi surface, we then observe the opening of a Δ≃0.9 meV temperature-dependent pairing gap. This result suggests for the first time, to our knowledge, that Li-decorated monolayer graphene is indeed superconducting with Tc≃5.9K.Press release (—A team of researchers from Germany and Canada has found a way to make graphene superconductive—by doping it with lithium atoms. In their paper they have uploaded to the preprint server arXiv, the team describes the process they used and the results they obtained when testing it. Charge-transfer doping of graphene by lithium adatoms. Credit: arXiv:1508.05925 [cond-mat.supr-con] Samsung develops lithium-ion battery with nearly double the life By now, most everyone in the science community is aware of graphene, the single carbon atom layer of material that is being studied to figure out how it can be mass produced and connected to other devices to take advantage of its superior electrical properties. Some have also been looking into whether the material could be made into a superconductor—prior research a decade ago showed that graphite could be made superconductive by coating it with other materials. Since that time, the search has been on to find just the right coating for graphene. Three years ago, a group in Italy created a model that suggested lithium might be the right choice, now, based on the work done by this latest team, it appears that they might have been right.In this effort, the researches first grew samples of graphene on a silicon-carbide substrate—those samples were then placed in a vacuum and cooled to 8K and were then “decorated” very precisely with a layer of lithium atoms. To convince themselves that the result was superconductive, the team tested the material with angle-resolved photoemission spectroscopy—doing so revealed that electrons sent through the material slowed down, which they suggest was the result of electron-phonon coupling (the creation of Cooper pairs)—one of the hallmarks of a superconductor. The team also identified an energy gap between those electrons that were conducting and those that were not, energy that would be needed to brake electron-phonon coupling.Further tests will have to be done to discover if it is possible to demonstrate a complete loss of electrical resistance and the expulsion of an external magnetic field, tests that can prove the material to be a true superconductor. 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. In related news, another group working at Sungkyunkwan University in South Korea has also been working with coating graphene with lithium and in their paper also uploaded to arXiv, they claim they have observed superconductivity in samples of layers of graphene doped with lithium.center_img © 2015 University of British Columbia physicists have been able to create the first superconducting graphene sample by coating it with lithium atoms. Credit: University of British Columbia Journal information: arXiv Citation: Graphene made superconductive by doping with lithium atoms (2015, September 2) retrieved 18 August 2019 from Explore furtherlast_img read more

Electrically tunable metasurfaces pave the way toward dynamic holograms

first_img Journal information: Applied Physics Letters High-efficiency color holograms created using a metasurface made of nanoblocks A new metasurface composed of silicon nanodisks integrated into a liquid crystal can be electrically tuned by turning a voltage “on” and “off.” The change in voltage changes the orientation of the liquid crystal molecules, which in turn changes the optical transmission of the metasurface. Credit: Komar et al. Published by AIP Publishing Citation: Electrically tunable metasurfaces pave the way toward dynamic holograms (2017, March 2) retrieved 18 August 2019 from (—Dynamic holograms allow three-dimensional images to change over time like a movie, but so far these holograms are still being developed. The development of dynamic holograms may now get a boost from recent research on optical metasurfaces, a type of photonic surface with tunable optical properties. More information: Andrei Komar et al. “Electrically tunable all-dielectric optical metasurfaces based on liquid crystals.” Applied Physics Letters. DOI: 10.1063/1.4976504ABSTRACTWe demonstrate electrical tuning of the spectral response of a Mie-resonant dielectric metasurface consisting of silicon nanodisks embedded into liquid crystals. We use the reorientation of nematic liquid crystals in a moderate applied electric field to alter the anisotropic permittivity tensor around the metasurface. By switching a control voltage “on” and “off,” we induce a large spectral shift of the metasurface resonances, resulting in an absolute transmission modulation of up to 75%. Our experimental demonstration of voltage control of dielectric metasurfaces paves the way for new types of electrically tunable metadevices, including dynamic displays and holograms.center_img In a new study published in Applied Physics Letters, a team of scientists at The Australian National University in Canberra, Australia; Friedrich Schiller University Jena in Jena, Germany; and Sandia National Laboratories in Albuquerque, New Mexico, US, has demonstrated a new way to tune optical metasurfaces.A metasurface is a thin sheet consisting of a periodic array of nanoscale elements. The exact dimensions of these elements is critical, since they are specifically designed to manipulate certain wavelengths of light in particular ways that enhance their electric and magnetic properties. Here, the scientists demonstrated how to manipulate a metasurface by applying an electrical voltage. By switching the control voltage “on” and “off,” the researchers could change the optical transmission of the metasurface. For instance, they could tune the transmission from opaque to the transparent regime for certain wavelengths, achieving a transmittance change of up to 75%. The voltage switch could also change the phase of certain wavelengths by up to 180°.”We demonstrate a new technology platform that enables tuning of optical metasurfaces with large contrast by simple application of a voltage,” Dragomir Neshev, a physics professor at The Australian National University, told “From an application perspective, it adds to the significance that our tuning concept is based on a similar technology as used in commercial liquid crystal displays, which would largely facilitate the translation of our concept to real-world applications of tunable metasurfaces.”The way this tuning works is that the voltage physically changes the elements of the metasurface. The metasurface is made of a square lattice of 600-nm-diameter silicon nanodisks embedded into a liquid crystal. When the voltage is “off,” the elongated molecules of the liquid crystal lie parallel to the metasurface. Turning the voltage “on” reorients the liquid crystal molecules so that they stand up perpendicular to the metasurface. Light waves interact with the metasurface differently depending on the orientation of the liquid crystal.While other methods of metasurface tuning have been suggested, these have various drawbacks, such as that they work slowly and require assistance that makes them impractical for immediate applications. Since the new electrically tunable metasurface works quickly and simply, the researchers expect that the method could have a wide variety of applications, including dynamic holograms, tunable imaging, and active beam steering.”Regarding a long-term vision or inspiration for the development of dynamic holographic devices, we can watch almost any science fiction movie,” Neshev said. “Most of them feature holographic man-machine interaction devices for visualization and communication purposes, where the hologram moves and changes in time based on user input. “While we are still far from this goal, a realistic medium-term application of our metasurfaces are tunable lenses for laser microscopy applications and beam shapers with enhanced functionalities, such as polarization selective response. Active beam steering or beam shaping could be applied in communications or as components in optical laboratory setups.” © 2017 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.last_img read more

Micromotors are powered by bacteria controlled by light

first_imgA micromotor, with microchambers shown in the inner cylindrical structure. Credit: Vizsnyiczai et al. Published in Nature Communications. Citation: Micromotors are powered by bacteria, controlled by light (2017, July 13) retrieved 18 August 2019 from Video of micromotors rotating in unison. Credit: Vizsnyiczai et al. This is essentially what the micromotors do. The microchambers along the edges of each micromotor are tilted at an angle of 45°, which maximizes the total torque with which the bacteria can cause the motors to rotate. In their design, the researchers also built a radial ramp with strategically placed barriers that direct the swimming bacteria into the microchambers. In experiments, the researchers found that a micromotor’s rotational speed increases linearly with the number of captured bacteria, and they could easily achieve rotational speeds of 20 revolutions per minute. Another important requirement for any bacteria-powered micromotor is the ability to control the micromotor’s motion. To do this, the researchers genetically modified the E. coli strain to express a light-driven proton pump called proteorhodopsin that uses photon energy to pump protons against the electrochemical gradient, which increases the bacteria’s swimming speeds. By illuminating the bacteria-powered micromotors with different light intensities, the researchers could then control the speed of the micromotors.In order for these systems to be used in practical applications, it’s also important that all of the micromotors in an array have average speeds that are uniform and have little fluctuation. With the help of a feedback algorithm that uniformly illuminates the system every 10 seconds, the researchers demonstrated that the micromotors can effectively be synchronized with very little variation in speed. Using this light-control method, the researchers could rotate a set of micromotors in unison at a particular speed.The bacteria-propelled micromotors have potential medical applications, such as drug and cargo delivery, which the researchers plan to investigate in the future. Microgears rotate when pushed by tiny motors More information: Gaszton Vizsnyiczai et al. “Light controlled 3D micromotors powered by bacteria.” Nature Communications. DOI: 10.1038/ncomms15974 The researchers, led by Roberto Di Leonardo, a physics professor at Sapienza Università di Roma and at NANOTEC-CNR, both in Rome, have published a paper on the bacteria-powered micromotors in a recent issue of Nature Communications.”Our design combines a high rotational speed with an enormous reduction in fluctuation when compared to previous attempts based on wild-type bacteria and flat structures,” said Di Leonardo. “We can produce large arrays of independently controlled rotors that use light as the ultimate energy source. These devices could serve one day as cheap and disposable actuators in microrobots for collecting and sorting individual cells inside miniaturized biomedical laboratories.”A fluid such as the one used here, which contains large amounts of swimming bacteria, is called an “active fluid” due to the mechanical energy it contains. In order for active fluids to be used as a fuel for propelling micromachines, the disordered motion of the bacteria must be controlled so that all (or most) of the bacteria move in the same direction. (—When researchers deposit a drop of fluid containing thousands of free-swimming, genetically engineered E. coli onto an array of micromotors, within minutes the micromotors begin rotating. Some of the individual bacteria have swum head-first into one of the 15 microchambers etched on the outer edge of each micromotor, and with their flagella protruding outside the microchambers, together the swimming bacteria cause the micromotors to rotate, somewhat similar to how a flowing river rotates a watermill. Explore further © 2017 Journal information: Nature Communications 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

New Caledonian crows found able to infer weight of an object by

first_imgCredit: CC0 Public Domain Crows and kea parrots found to learn usefulness of objects similar to the way human babies do it Citation: New Caledonian crows found able to infer weight of an object by watching how it behaves in the wind (2019, January 9) retrieved 18 August 2019 from Humans can easily gauge the weight of objects by their behavior under windy conditions. In breezy conditions, a napkin will fly off a table at an outdoor café, for example, but a fork generally will not. We prepare for this eventuality by placing something heavy on the napkin, but not on the fork. But until now, no other creature has been found to have this ability.To find out if New Caledonian crows might have this ability, the researchers went out into the wild and captured 12 specimens and brought them back to their lab. All of the birds were taught to use the weight of an object as the criteria needed in order to receive a food reward. Half were taught that the lighter of two objects was needed, while the other half were taught that it was the heavier object that was needed to get their reward.Next, the researchers strung the same objects a few inches off the ground, one by one, and pointed a fan at them to simulate a breeze. The light objects would blow around easily, while the heavy ones remained stationary. The birds were then brought individually into the test area. Each watched as two objects were blown by the fan—the crows were then allowed to pick one of the objects as a means for receiving their treat.The researchers report that the birds were 73 percent correct in choosing the object that would get them their reward, all without having touched the objects prior to choosing them. They claim that this very strongly suggests that the birds were able to figure out which of the objects were heavier and which were lighter simply by watching how they behaved under windy conditions. A team of researchers with members affiliated with the University of Auckland, the University of Cambridge, Bertha von Suttner University and the Max Planck Institute for the Science of Human History has found evidence that suggests New Caledonian crows can infer the weight of an object by watching how it behaves in the wind. In their paper published in Proceedings of the Royal Society B, the group describes experiments they carried out with crows they captured and what they found. © 2019 Science X Networkcenter_img Explore further More information: New Caledonian crows infer the weight of objects from observing their movements in a breeze, Proceedings of the Royal Society B (2019). … .1098/rspb.2018.2332 Journal information: Proceedings of the Royal Society B 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

Xray observations reveal insights into the nature of the pulsar wind nebula

first_img Radio nebula discovered around the pulsar PSR J0855–4644 Citation: X-ray observations reveal insights into the nature of the pulsar wind nebula 3C 58 (2019, April 23) retrieved 18 August 2019 from Analysis of the new data from X-ray observations using NASA’s NuSTAR spacecraft and archival data from the agency’s Chandra X-ray space observatory, has yielded more insights into the nature of a pulsar wind nebula (PWN) named 3C 58. Results of the analysis, presented in a paper published April 12 on, could also shed more light on particle distribution in the population of known PWNe. Explore further © 2019 Science X Network PWNe are nebulae powered by the wind of a pulsar. Pulsar wind is composed of charged particles and when it collides with the pulsar’s surroundings, in particular with the slowly expanding supernova ejecta, it develops a PWN. Observations of PWNe have shown that the particles in these objects lose their energy to radiation and become less energetic with distance from the central pulsar. In particular, X-ray studies of PWNe, especially using spatially-integrated spectra in the X-ray band, have the potential of uncovering important information about particle flow in these nebulae.Located some 6,500 to 10,000 light years away from the Earth, 3C 58 is a young PWN with torus-jet structure and powered by the 65-milisecond pulsar PSR J0205+6449. While the object has been intensively studied in the soft X-ray band (below 8.0 keV) and hence its soft X-ray spectrum is well modeled, astronomers are interested in verifying if the spectrum extends to hard X-ray band above 10 keV.In order to check this, a group of researchers led by Hongjun An of Chungbuk National University in Cheongju, South Korea employed the Nuclear Spectroscopic Telescope Array (NuSTAR) spacecraft to perform spectral analysis of 3C 58 up to 20 keV. They also reanalyzed the Chandra data for comparison with results from NuSTAR.The astronomers measured the energy-dependent morphology, spatial variation of the spectral index, and a spatially integrated broadband X-ray spectrum of 3C 58. “These measurements are used to infer properties of 3C 58 with synchrotron-radiation scenarios,” the researchers wrote in the paper.The results indicate that the size of the 3C 58 decreases with increasing energy, what, according to the researchers is due to the synchrotron burn-off effect. The data also show that the spectrum is softer in outer regions of this PWN.Moreover, the researchers found a hint of a spectral break in the spatially integrated X-ray spectrum and a break in the radial profile of the spectral index of 3C 58.”The radial profile of the spectral index breaks at R ≈ 80, and the spatially integrated X-ray spectrum of 3C 58 shows a hint of a spectral break at ≈ 25 keV,” the paper reads.According to the study, the break in the radial profile indicates a maximum electron energy of about 200 TeV, what is larger than previously estimated. When it comes to the spectral break, the data suggests a maximum electron energy of approximately 140 TeV for an assumed magnetic field strength of 80 μG. Additionally, the strength of the magnetic field in 3C 58 was calculated to be between 30 and 200 μG.All in all, the astronomers concluded that their study could advance our knowledge about acceleration and emission models of PWNe. They noted that in the case of 3C 58, its well measured broadband spectral energy distribution and the possible X-ray break, have the potential to provide new insights into particle acceleration and flow in PWNe. More information: Hongjun An. NuSTAR hard X-ray studies of the pulsar wind nebula 3C~58. arXiv:1904.05991 [astro-ph.HE]. NuSTAR images of 3C 58 in six energy bands. The energy bands for the images are 3–4.5 keV, 4.5–7 keV, 7–12 keV, 12–20 keV, 20–40 keV, and 40–60 keV from left to right and top to bottom. The images are smoothed and the scales are adjusted to have a value of 1 at the maximum for better legibility. Chandra white contours are overlaid in the top-left panel for reference. Credit: An et al., 2019. 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

Bolly number for Chinese new year

first_imgChinese opera singer Bowang surprised one and all when she belted out a hit Bollywood number from the Shah Rukh Khan-starrer Mohabbatein at the Chinese Spring Festival 2013.After her opera performance, she sang the hit Hindi song Ankhein khuli ho ya hon bandh at the FICCI Auditorium here Monday.The festival, organised by the India China Economic and Cultural Council here on the occasion of the Chinese New year, which fell on 10 February, also saw a spectacular display of acrobatics, group dances, and traditional music of China. The highlight of the festival was acrobatics performed by Peng Li and Guang Zhang.   There were performances by Sihong Zho, a dance performance, bits of Peking Opera, solo dance. Baba Deep Singh Ranjeet Akhara did the gatka (a form of Indian martial arts).last_img read more