Month: August 2019

Acer announces the Iconia Tab A500 with Android 30 Honeycomb

first_img © 2010 PhysOrg.com 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 further Citation: Acer announces the Iconia Tab A500 with Android 3.0 Honeycomb (2011, February 14) retrieved 18 August 2019 from https://phys.org/news/2011-02-acer-iconia-tab-a500-android.html AT&T, Sprint, T-Mobile, Verizon to sell Samsung’s iPad rival (PhysOrg.com) — Acer is making a new move into the world of tablets. They showed off their new Iconia Tab A500. The device features the Google’s Android 3.0 Honeycomb software and an interesting set of hardware specs. The Iconia Tab A500 has a 10.1-inch display, with a a wide viewing angle and a screen that allows for a high degree of color contrast. This, of course, put the new tablet on par with the Motorola Xoom and Samsung Galaxy Tab 10.1, at least for screen size. The screen also supports HD video formats, with a built-in HDMI port that will allow users to stream video from the tablet in 1080p HD. Which is good news if you love movies, but is not of much use to you if videophile is not on your social resume.The case is laser-engraved and made out of aluminum. The whole device is set to be 13.3mm thick. The Iconia Tab A500 also has a decent processor, it features a dual-core Nvidia Tegra 2 processor and an Nvidia GeForce GPU in order to handle next-generation graphics. The Iconia Tab A500 will come with choice of Wi-Fi or 3G for the Internet connection, which is a fairly standard set of choices in the tablet world. It also features a dual set of cameras. The one in the rear is a 5-megapixel and the front camera is what an high definition front cam for video calls, thought you may not always want to see your chat partners in HD. The camera also has the ability to be used as a barcode reader.The tablet does not have a release date announced or a cost listed currently.last_img read more

Intel Ultrabooks will be thin and light but heavy in innovation

first_img More information: software.intel.com/en-us/vcsou … eptual-computing-sdk A voice-recognition tool by Nuance called Dragon Assistant will start appearing in Dell ultrabooks later this year. A demo at the IDF featured a Dell XPS 13 Ultrabook running Nuance’s Dragon Assistant Beta.With next month’s release of Windows 8 from Microsoft, 40 upcoming Ultrabooks based on Windows 8 will be touch-enabled.Talk of the upcoming Ultrabooks at the IDF was laced with the key technology driver behind future innovation-loaded Ultrabooks, and that is Haswell, Intel’s upcoming processor architecture. Intel fashioned Haswell with beefed-up Ultrabooks in mind. Haswell can allow for the Ultrabook’s upcoming innovations, with a design that enables lower power requirements, power boosts, and more efficient energy management. Haswell’s capabilities translate into Ultrabook capabilities. The Haswell design carries the same 22-nm process as Ivy Bridge, but will deliver better power management and battery life. Haswell processors will support Intel customers building a new crop of tablet-morphing form factors, where a flip or swivel or fold-back changes the laptop into a tablet. There are about 70 ultrabooks on the market at the moment. Next year, Intel is banking on doubling that number. 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 further Citation: Intel: Ultrabooks will be thin and light but heavy in innovation (2012, September 12) retrieved 18 August 2019 from https://phys.org/news/2012-09-intel-ultrabooks-thin-heavy.html To prep developers, Intel announced this week that it will release an introductory software developer package, the Intel Perceptual Computing SDK 2013 Beta, in October. Developers will be able to add perceptual computing usage for immersive software applications that incorporate close-range tracking, speech recognition, facial analysis and 2-D/3-D object tracking on second and third generation core processor-powered Ultrabooks and PCs. This SDK supports the CREATIVE Interactive Gesture Camera Developer Kit, a USB-powered depth sensor camera tuned for short-range interactivity. This is for Intel-powered Ultrabooks, laptops or PCs used within a range of six inches to three feet. The camera developer kit, said Intel, will be available in Q4 of this year. Intel has also announced a Perceptual Computing Challenge with up to $1 million in awards and promotions for application developers. Intel will highlight next-gen Haswell processors at next week’s IDF (Phys.org)—Intel’s new breed of Ultrabooks will be lighter, thinner but loaded with new features and functions that end users will either see as bloat or muscle, and Intel is counting on the latter. The look and functions of Intel’s next-generation Intel Ultrabooks were revealed by Intel executives at the Intel Developer Forum. The new computers will bring in voice recognition, touch, finger tracking, augmented reality, and gesture-based interfaces. The technologies that generally are expected out of smartphones and tablets will be applied toward the thin and light computers. Ultrabook manufacturers will start to integrate sensors gyroscopes, accelerometers, GPS, NFC, and 3G and 4G-LTE connectivity. © 2012 Phys.orglast_img read more

Quantumcritical conductivity of the Dirac fluid in graphene

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. Quantum-critical scattering rate of the Dirac fluid. (A) Real and (B) imaginary parts of the change in optical conductivity at charge neutrality upon optically heating the electron system to a temperature Te above the equilibrium temperature T0 = 77 K. Each curve corresponds to a different delay between the optical pump pulse (fluence 21 nJ cm–2) and terahertz probe pulse. Solid curves are fits to a difference between Drude functions at Te and T0, using Te and the scattering rate τ–1(Te) as free fit parameters for each pair of curves of the complex conductivity. (C) Blue markers indicate the scattering rates and electron temperatures extracted from the fits shown in (A) and (B); error bars indicate standard error in the fits. The experimental scattering rate follows τ–1 = τee–1 + τd –1 (dashed curve), where τee–1 = 0.20kBTe/ħ (green line) is the scattering rate due to charge-carrier interactions, and τd –1 ∝ nimpTe –1 (dotted curve) is the scattering rate due to unscreened, singly charged impurities with density nimp = 2.1 × 109 cm–2. (D) Real and imaginary parts (open and filled circles, respectively) of σ at different Te (i.e., different optical pump delay), replotted as a function of ħω/kBTe. The data for Te = 100 K (21.3 ps delay) do not collapse and are omitted. Credit: Science, doi: 10.1126/science.aat8687 In all measurements, the scientists heavily doped the graphene beneath the waveguide traces to minimize its impedance. The extracted scattering rates at 77 K were below 0.5 and 1 THz, indicating infrequent scattering by disorder and phonons, consistent with previous transport studies of similar doping; thus confirming the anticipated Fermi liquid behavior of graphene. The scientists probed the transport at charge neutrality by observing the change in terahertz transmission. For this, they optically heated the system and calculated the corresponding change in conductivity and the current carried in charge-neutral graphene under experimental conditions. The observed linear evolution in the experiments was a key signature of charge-carrier interactions in the quantum-critical Dirac fluid. More information: Patrick Gallagher et al. Quantum-critical conductivity of the Dirac fluid in graphene, Science (2019). DOI: 10.1126/science.aat8687 K. S. Novoselov et al. Two-dimensional gas of massless Dirac fermions in graphene, Nature (2005). DOI: 10.1038/nature04233 Experimental setup. Left: Large-area photograph of the waveguide device. Right: Cross-sectional view of the heterostructure beneath the waveguide electrodes. Credit: Science, doi: 10.1126/science.aat8687 Experimentally, time-domain terahertz spectroscopy is an ideal probe across a broad frequency range to observe quantum-critical conductivity, but use of the device is limited to lower-quality large-area films, within which Dirac fluid physics is obscured. In the present work, therefore, Gallagher et al. leveraged the subwavelength confinement of a coplanar waveguide to measure the terahertz optical conductivity of graphene, at ten-micron scale thickness ,encapsulated within hexagonal boron nitride (HBN). They used the experimental setup to measure the material’s conductivity at electron temperatures (Te) ranging between 77 and 300 K to confirm the quantum-critical scattering rate near charge neutrality. The scientists also demonstrated the co-existence of zero- and finite-momentum modes at non-zero doping. Frequency-dependent optical conductivity of graphene in the Fermi liquid regime. (A) Real and (B) imaginary parts of extracted optical conductivity for several Fermi energies between 46 and 119 meV (electron doping) at 77 K. Solid curves are Drude fits using only the scattering rate τ–1 as a free fitting parameter for each curve. Inset in (A) shows an example of the time-domain current data used to extract conductivity in the frequency domain; the purple trace shows the transmitted waveform at 119 meV, and the black trace shows the transmitted waveform at charge neutrality, which is used as a reference. Inset in (B) shows the extracted τ–1 at lattice temperatures 77 K and 300 K. Credit: Science, doi: 10.1126/science.aat8687 In this way, Gallagher et al. elegantly demonstrated the quantitative agreement between the experimental results and relativistic hydrodynamic theory of the Dirac fluid graphene. The scientists implied that graphene should host relativistic phenomena that are not observed in typical electron systems (to which relativistic hydrodynamics do not apply). For instance, in conventional metals, electronic sound waves either morph into plasmons or are destroyed by momentum relaxation. However, the new results indicate that such waves can exist in charge-neutral graphene as a result of low disorder and zero-coupling to plasmon modes. The experimental work by Gallagher et al. thus provided access to the subtle and rich physics of relativistic hydrodynamics of graphene in a bench top experiment. Further experiments can investigate the cyclotron resonance of graphene at high temperatures in the future. The work revealed the quantum criticality of the material in which each site is in a quantum superposition of order and disorder (similar to Schrödinger’s hypothetical cat in a quantum superposition of ‘dead’ and ‘alive’) and the unusual dynamic excitation in graphene near charge neutrality. Physicists consider quantum relativistic effects in the experimental systems influencing condensed matter to be too minute for accurate description by the non-relativistic Schrödinger’s equation. As a result, previous studies have reported on experimental condensed matter systems such as graphene (a single atomic layer of carbon) in which electron transport was governed by Dirac’s (relativistic) equation. Landau’s theory of the Fermi liquid defines electron interactions of a typical metal as an ideal gas of non-interacting quasiparticles. In monolayer graphene, this description does not apply due to its structure of linearly dispersing bands and minimally screened Coulomb interactions. Near charge neutrality, graphene is thus expected to host a “Dirac fluid,” which is a quantum-critical plasma of electrons and holes that are governed by relativistic hydrodynamics. In lightly doped graphene, a surprising consequence of relativistic hydrodynamics is that current can be carried by two distinct modes; with zero and non-zero total momenta, also referred to as “energy waves” and “plasmons” in some studies. Coexistence of zero- and finite-momentum modes at low doping. (A) Calculated Drude weights DZ and DF of the zero- and finite-momentum modes (27) in lightly electron-doped (εF = 33 meV) and undoped graphene. (B) Real and (C) imaginary parts of the measured change in optical conductivity when charge neutral graphene in equilibrium (T0 = 77 K) is simultaneously heated to an electron temperature Te (optical pump delay 3 ps, fluence 21 nJ cm–2) and doped to εF = 33 meV. (D) Real and (E) imaginary parts of the measured change in optical conductivity when charge neutral graphene at an electron temperature Te (optical pump delay 4 ps, fluence 20 nJ cm–2) is doped to various εF. Data at each doping are well fit by a single Drude function (solid curves) describing the conductivity of the finite-momentum mode with free fit parameters Te = 267 ± 3 K and τd –1(εF) ~ 1 THz. Inset in (D) shows the scattering rate for the finite momentum mode τd –1 versus Te extracted from fits at varying Te. Colors indicate εF as in (D), (E). Credit: Science, doi: 10.1126/science.aat8687 Graphene is expected to behave like a quantum-critical, relativistic plasma known as “Dirac fluid” near charge neutrality in which massless electrons and holes rapidly collide. In a recent study now published in Science, Patrick Gallagher and co-workers at the departments of physics and materials science in the U.S., Taiwan, China and Japan used on-chip terahertz spectroscopy and measured the frequency-dependent optical conductivity of graphene between 77 K and 300 K electron temperatures for the first time. Additionally, the scientists observed the quantum-critical scattering rate characteristic of the Dirac fluid. At higher doping, Gallagher et al. uncovered two distinct current-carrying modes with zero and nonzero total momenta as a manifestation of relativistic hydrodynamics.center_img © 2019 Science X Network Citation: Quantum-critical conductivity of the Dirac fluid in graphene (2019, March 13) retrieved 18 August 2019 from https://phys.org/news/2019-03-quantum-critical-dirac-fluid-graphene.html Explore further In the experimental setup, Gallagher et al. used photoconductive switches made of semiconducting materials with approximately one picosecond (ps) carrier lifetime to accomplish emission and detection of terahertz pulses. The emitter switch contacting the lower waveguide trace was biased with a dc voltage. When triggered by a laser pulse, the biased emitter became highly conductive for 1 ps. The process injected a current pulse into the coplanar waveguide to interact with graphene prior to reaching a detector switch spanning both traces. In practice, the scientists obtained lower noise by controlling the length of the optical path and detecting the current, to measure the time-domain profile of the transmitted voltage pulse (dV/dt). After optimizing experimental conditions, the scientists first investigated the optical conductivity of the Fermi liquid at 77 K (T0). The transmitted waveforms contained sharp, sub-picosecond features that evolved with gate voltage to result in maximum transmission at charge neutrality. To extract the optical conductivity from the time-domain data and justify the finite-element simulations, the scientists modeled the device as an infinite, lossless transmission line. Gallagher et al. then probed transport at charge neutrality by observing the change in terahertz transmission (∆V) by optically heating the electron system from T0 = 77 K to varying electron temperatures (Te). To vary temperature in the experimental setup, they adjusted the delay between the optical pump and terahertz probe pulse. Journal information: Science Hall effect becomes viscous in graphene Probing the electrodynamics of graphene using on-chip terahertz spectroscopy. (A) Current carrying modes of a graphene sheet. The zero-momentum mode corresponds to a plasma of counterpropagating electrons and holes and can be relaxed by electron-hole interactions. The finite-momentum mode corresponds to a fluid of co-propagating electrons or holes with nonzero net charge and cannot be relaxed by charge-carrier interactions. The vector J denotes the net current flow. (B) Cartoon of the sample. Photoconductive switches (“emitter” and “detector”) triggered by a pulsed laser emit and detect terahertz pulses within the waveguide. The transmitted pulse is reconstructed by measuring the current collected by the preamplifier (“A”) as a function of delay between laser pulse trains illuminating the emitter and detector. The graphene is optionally excited by a separate pulsed beam (“pump”) to heat the electron system. (C) Photograph of the heterostructure embedded in the waveguide. Few-layer graphene (FLG) electrodes make contact to the monolayer graphene sheet under study and the WS2 gate electrode. Scale bar: 15 micron. Credit: Science, doi:10.1126/science.aat8687 , Nature As doping increased, the weight of the zero-momentum mode was expected to decrease, while that of the finite-momentum mode increased to cross over smoothly from Dirac fluid to Fermi liquid behavior. Previous experiments on clean, monolayer graphene have demonstrated many-body physics in graphene, with examples including studies on low-frequency transport phenomena consistent with hydrodynamic descriptions. Additional experiments indicated violation of the Wiedemann-Franz law – as a signature of the Dirac fluid and as direct evidence of collective motion in a quantum electronic fluid, and the viscous flow of electrons. Even though electron-hole collisions have shown to limit conductivity in charge-neutral bilayer graphene, the direct observation of quantum-critical conductivity of the Dirac fluid has remained elusive. last_img read more

Testing Einsteins equivalence principle near a supermassive black hole

center_img More information: A. Amorim et al. Test of the Einstein Equivalence Principle near the Galactic Center Supermassive Black Hole, Physical Review Letters (2019). DOI: 10.1103/PhysRevLett.122.101102 Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole, Astronomy & Astrophysics (2018). DOI: 10.1051/0004-6361/201833718 “General relativity and in general all metric theories of gravity are based on the equivalence of inertial mass and gravitational mass, formalized in the Einstein equivalence principle,” Maryam Habibi, one of the researchers who carried out the study, told Phys.org. “General relativity is the best theory of gravity that we have, however, there are still many unanswered puzzles that are closely tied to our incomplete understanding of gravity.” The equivalence principle, a crucial part of Einstein’s general relativity theory, states that the gravitational force experienced in any small region of space-time is the same as the pseudo-force experienced by an observer in an accelerated frame of reference. Testing this principle is of key importance, as it could lead to interesting observations and broaden our current understanding of gravity. “Einstein’s equivalence principle consists of three main principles,” Habibi explained. “One of them, called the local position invariance (LPI), states that non-gravitational measurements should be independent of the location in space time (characterized by gravitational potential) where they are carried out. The main part of our study focuses on testing the LPI principle.”Past observations suggest that most, if not all, massive galaxies contain a supermassive black hole, which is typically located at the center of a galaxy. The mass of the Milky Way’s galactic center supermassive black hole is 4 million times greater than that of the sun. It thus generates the strongest gravitational field in the galaxy, which makes it the ideal place to hunt for unexplored phenomena and test general relativity principles.Star S2, one of the brightest stars in the Milky Way’s innermost region, has its closest encounter with the galactic center supermassive black hole at a distance of 16.3 light hours. In other words, the star takes 16 years to make a complete orbit around the black hole, which in astronomical time scales is extremely short. S2 moves in and out of the black hole’s gravitational field, hence the GRAVITY collaboration team decided to use it to test part of Einstein’s equivalence principle. Journal information: Physical Review Letters Citation: Testing Einstein’s equivalence principle near a supermassive black hole (2019, March 29) retrieved 18 August 2019 from https://phys.org/news/2019-03-einstein-equivalence-principle-supermassive-black.html , Astronomy & Astrophysics Image shows one of the Unit Telescopes of ESO’s Very Large Telescope (VLT) array, pointing a laser beam towards the Milky Way to create an artificial star. Credit: European Southern Observatory (ESO).last_img read more

Researchers outline the current state of potassiumion battery technology

center_img Citation: Researchers outline the current state of potassium-ion battery technology (2019, May 13) retrieved 18 August 2019 from https://phys.org/news/2019-05-outline-current-state-potassium-ion-battery.html Sodium- and potassium-based batteries could be key for smart grid of the future Opportunities and challenges of the PIB. (A) Comparison of LIB, SIB, and PIB in terms of energy density. (B) Abundance of lithium, sodium, and potassium metal in Earth’s crust (wt %). (C) Stokes radius of Li+, Na+, and K+ in PC. (D) Number of publications on PIBs according to Google Scholar (as of January 2019). (E) Summary of challenges and their relationships for the PIB. Credit: Science Advances (2019). DOI: 10.1126/sciadv.aav7412 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

Project Shankar Market makeover

first_imgThe pale, weary and pan-stained walls and corridors of one of Delhi’s oldest shopping destinations – Shankar Market – opposite Connaught Place’s outer circle is in the makeover mode as street artists are painting its eight blocks in varied hues and narrations depicting music, dance and drama to increase the footfalls.The New Delhi Municipal Council (NDMC) has joined hands with Delhi Street Art (DSA) to reinvent and refurbish the market, best-known to many as ‘fabric market’ for women. This is the second phase of the refurbishing project that NDMC is doing after it completed its long-delayed renovation work of the Connaught Place in December, 2013. Also Read – ‘Playing Jojo was emotionally exhausting’‘To use street art for reinventing this market has been on our mind for a long time now. When the market association approached us to do something to increase their footfall, as the market was in bad condition, we thought using colourful street art can be the best way to develop this market,’ OP Mishra, NDMC’s director (Projects) said.‘This is the second phase of the refurbishing project, and we plan to restore all other arterial markets around Connaught Place. We have hired an architecture to restore Gole market to its original glory,’ he added. Also Read – Leslie doing new comedy special with NetflixBringing out art from the closed and plush confines of art galleries to the public places is what DSA has been doing, and according to Yogesh Saini, by the end of the project, Shankar Market will offer a ‘continuous cultural feast’ to the public.‘The aim is to convert this market into “rainbow street”,’ Saini, the brain behind DSA, said.‘We had given the artists guidelines and used themes like music, culture, food and dance to attract the attention of people, especially younger audience,’ he added. As the first flour blocks of the market were painted Saturday and Sunday, Saini aims to paint another three blocks by next weekend. That will leave the group with one tall building which will require certain logistics preparations before they paint it.‘There were 5-6 artists per building and we have more than 40 artists on board with us,’ he added.According to Saini, they have also suggested the officials to add some rooftop kiosks and shops to convert it into a buzzing hang-out place.This is the second time the DSA have collaborated with NDMC. Their first project was to paint garbage bins of the Lodhi garden which they undertook eight months back. Saini feels such initiatives help in bringing street art into the public domain and help the common man to understand art.last_img read more

Four arrested for extorting money posing as CID officials

first_imgKolkata: Howrah police have arrested four persons on the charges of extorting money posing as CID officials.The incident took place at Howrah’s Uluberia on Sunday night. The accused were extorting money from the heavy duty trucks in Malpara area of Uluberia on the National Highway 6. Police said the accused parked a car fitted with beacon light and a sticker of ‘Income Tax’ on the car.The accused stopped loaded trucks on the National Highway 6 on Sunday night and demanded a huge amount of money. Also Read – Heavy rain hits traffic, flightsThey introduced themselves as CID officials and also threatened the drivers with dire consequences if they failed to meet their demands. After being informed, police rushed to the spot. The accused managed to flee the spot before the police could reach.A truck driver told the police that the accused took around Rs 3,000 and a mobile phone from him. Police then chased the vehicle and managed to intercept the car a few kilometers away from the spot. Police arrested the four accused on various charges. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedPolice said the accused flashed fake ID cards while extorting money from the truck drivers. According to preliminary investigation, police came to know that the impostors used to conduct raids at various shops.The accused have been charged with cheating and extortion posing as CID officers. “They are being interrogated and we are also investigating whether more people are involved with the gang,” a senior police officer in the district said.According to police, the accused are all residents of Taratala area in the city. The investigators are yet to confirm the identity of the accused, aged between 30 and 35. Police said the accused used to conduct fake raids at various places posing as CID officials. Police have started a detailed probe in this regard.last_img read more