Apple patents an inexpensive 3D projection system

first_img Explore further (PhysOrg.com) — The U.S. patent office has granted Apple a patent for a 3-D projection system that doesn’t require the use of bulky 3-D glasses. This gives the viewer more freedom of movement and viewing angles. Apple is not the only company that’s involved in auto-stereoscopic R&D; however Apple’s patent has picked apart the limitations of three categories of auto-stereoscopic system:1. Ghost like or transparent images in volumetric displays. 2. The viewer required to remain stationary using the parallax barrier method.3. The use of holographic images requires greater computer power and larger bandwidth, keeping the commercial cost higher that is required for other auto-stereoscopic systems. Apple patent application for 3D viewing glasses The name Apple has given to this simple 3-D system is called, “Three Dimensional Display System.” This auto-stereoscopic system works by projecting each pixel onto a reflective, textured surface, which is then bounced into a viewer’s left and right eye separately; this produces the 3D or stereoscopic effect. By sensing the locations of both eyes of each viewer, multiple viewers could observe the 3-D effect from a variety of angles. Each pixel is aimed at a curved surface, where it reflects onto the correct eye. Citation: Apple patents an inexpensive 3-D projection system (2010, December 3) retrieved 18 August 2019 from https://phys.org/news/2010-12-apple-patents-inexpensive-d.html © 2010 PhysOrg.com Apple’s auto-stereoscopic system tracks where the viewer is located and tailors its display to your position. Apple’s main objective is to develop a 3-D glass-free auto-stereoscopic system that would give viewers the freedom to move around without being tied down to bulky 3-D glasses. Apple’s patent also promises to keep costs low and simplifying the system while maintaining performance. 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

Fast photon control brings quantum photonic technologies closer

first_img(PhysOrg.com) — Using photons instead of electrons to transmit information could lead to faster and more secure ways to communicate, among other advantages. Now a team of physicists has taken another step toward realizing quantum photonic technologies by demonstrating how to quickly manipulate single photons at the same wavelengths used in existing optical telecommunications networks. The ability to control a photon’s path and polarization in the time of a few nanoseconds could allow photonic circuits to be integrated with existing optical telecom networks, leading to significant improvements. Copyright 2012 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. Explore further Researchers demonstrate electo-optic modulation of single photons from a quantum dot 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 More information: Damien Bonneau, et al. “Fast Path and Polarization Manipulation of Telecom Wavelength Single Photons in Lithium Niobate Waveguide Devices.” PRL 108, 053601 (2012). DOI: 10.1103/PhysRevLett.108.053601 Citation: Fast photon control brings quantum photonic technologies closer (2012, February 13) retrieved 18 August 2019 from https://phys.org/news/2012-02-fast-photon-quantum-photonic-technologies.html The physicists, from the University of Bristol in Bristol, UK, Heriot-Watt University in Edinburgh, UK, and the Kavli Institute of Nanoscience in Delft, The Netherlands, have published their study on the fast control of the path and polarization of single photons in a recent issue of Physical Review Letters.The physicists worked on a quantum photonic device consisting of circuits through which single photons move, where the circuits can be reconfigured to change the path and polarization of a photon. One of the challenges for these quantum photonics circuits is to manipulate single-photon and multi-photon states at a fast rate.To address this challenge, the researchers used lithium niobate waveguides, which have proven to be capable of fast manipulation in current telecom modulators. By taking advantage of the electro-optic effect, the researchers demonstrated that applying a voltage to electrodes near the waveguide can rapidly manipulate quantum states of light made of one or two photons. They demonstrated this fast path and polarization control of photon pairs generated at the 1550-nm wavelength, which is used in telecom networks.“In this experiment, we demonstrate switching between two configurations of the circuit, each one leading to a different quantum state,” lead author Damien Bonneau of the University of Bristol told PhysOrg.com. “The reconfiguration rate was set at 4 MHz while previous experiments were performed with circuits reconfigured every several seconds. Switches using essentially the same technology are used every day in telecommunication networks to switch bits of information encoded in light pulses at 40 GHz. Such switches could in principle be used at a single-photon level too.”As Bonneau explained, the lithium niobate waveguide’s ability to manipulate quantum states of light provides a distinctly different approach compared with previous methods that worked much slower.“Until now, on-chip manipulation of quantum states of light had relied on heaters acting as slow phase shifters,” Bonneau said. “We demonstrate here that, by using one of the technologies on which the internet is built, one can not only switch light packets for routing classical information, but also rapidly engineer and manipulate quantum states of light.”As the scientists explained, the ability to rapidly control the polarization and path of single photons on a single platform will be useful for both fundamental quantum science and quantum technologies. They plan to expand their research to work toward several of these applications in the future.“Lithium niobate, the material which these devices are made of, can be used to probabilistically generate photons as well,” Bonneau said. “Superconducting single photon detectors could also be integrated onto such a chip. A technological platform combining probabilistic sources of single photons, circuits and detectors can open the way to several applications including reliable single-photon sources (by multiplexing several sources), quantum relays (required for long distance quantum communication), or quantum key distribution (which is required for quantum cryptography).”last_img read more

Physicists propose a way to make atomic clocks more accurate

first_img(Phys.org)—Physicists Andrei Derevianko of the University of Nevada and Victor Flambaum and Vladimir Dzuba of the University of New South Wales have proposed in a paper published in Physical Review Letters a way to improve on the accuracy of atomic clocks. They suggest stripping away electrons from ions to reduce the negative effects of stray fields that reduce the performance of current atomic clocks. Journal information: Physical Review Letters Explore further Proposed nuclear clock may keep time with the Universe More information: Highly Charged Ions as a Basis of Optical Atomic Clockwork of Exceptional Accuracy, Phys. Rev. Lett. 109, 180801 (2012) DOI: 10.1103/PhysRevLett.109.180801AbstractWe propose a novel class of atomic clocks based on highly charged ions. We consider highly forbidden laser-accessible transitions within the 4f12 ground-state configurations of highly charged ions. Our evaluation of systematic effects demonstrates that these transitions may be used for building exceptionally accurate atomic clocks which may compete in accuracy with recently proposed nuclear clocks.via PhysicsWorld Researchers continue to look for ways to increase the accuracy of atomic clocks because higher accuracy would allow for finer measurements of very small changes in the values of the physical constants that underlie some of the most basic principles of physics. One example is the fine structure constant – a more accurate measurement of its changes might lead the way to the development of a unified theory.Recent research has focused on switching to a nuclear clock as theories have indicated they might be more accurate than atomic clocks. Practical limitations, such as the high degree of difficulty in calculating frequency transitions and the danger of working with radioactive materials have prevented the development of such clocks however, which is what led this new effort to see if the model for an atomic clock could be improved.Atomic clocks are based on using atomic transitions as a means of defining a time standard and are accurate to one part in 1017. The goal is to improve that to 1019. To achieve such accuracy, the researchers propose stripping away some of the electrons of a particular ion to cause the remaining electrons to bind tighter to the nucleus. Doing so, they reason would reduce the stray fields that can creep into the electromagnetic trap used to measure the electronic transition, which skew the results. Based on that assumption, they’ve calculated that the observation of the electron transmission of a bismuth-209 ion would produce the desired accuracy.The researchers acknowledge that building such a clock would be difficult, but suggest it should be possible and argue that it would be much more practical than trying to build and work with a nuclear clock. They conclude by suggesting that the time has come to put more effort into improving the atomic clock and less into nuclear clock research. © 2012 Phys.org Citation: Physicists propose a way to make atomic clocks more accurate (2012, November 7) retrieved 18 August 2019 from https://phys.org/news/2012-11-physicists-atomic-clocks-accurate.html 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

Researchers find signs of western Eurasian genes in southern African Khoisan tribes

first_img Scientists believe humans evolved from ancestral primates in Africa several hundred thousand years ago, but it wasn’t until approximately 65,000 years ago that they made their way out of Africa and into the Middle East and eventually the rest of the world. Until recently, that migration has been viewed by most scientists as a one-way trip. Gene studies over the past several years has turned that thinking around, however, as its been found that many people in several parts of Africa have European or Asian gene segments in their DNA. In this latest study, the researchers have found evidence of Eurasian genes in tribespeople who were thought to have a purely African ancestry.The Khoisan tribespeople of today still live much as their ancestors did—they are hunter-gathers who are also pastoralists—they are most familiar to westerners as the people who speak with distinctive clicking noises. Until now, they were believed to have the purest African gene pool due to their thousands of years of isolationist practices. The team acquired DNA samples from 32 people living in Khoisan tribes in southern Africa—an analysis revealed Eurasian gene segments in all of them. But that wasn’t the end of the story. To understand how the gene fragments got into the Khoisan tribespeople, the researchers turned to archeological and linguistic evidence to build a possible time-line of events. In so doing, they’ve found what they believe to have been a migration back into Africa by people of the Middle East (ancestors of the people that migrated to Europe and Asia) approximately 3000 years ago. Those people made their way to various parts of the continent, including a part of eastern Africa from which the Khoisan tribespeople had migrated south approximately 900 and 1800 years ago.The researchers found something else—the Khoisan tribespeople also had snippets of Neanderthal DNA in their genes as well—courtesy of their Eurasian heritage. 33-year-old San tribesman from Namibia. Image: Wikipedia. Genetic admixture in southern Africa: Ancient Khoisan lineages survive in contemporary Bantu groups (Phys.org) —A team of researchers with representatives from the U.S., Germany and France has found evidence of western Eurasian genes in Khoisan tribes living in southern Africa. This suggests, the researchers conclude in a paper they’ve had published in Proceedings of the National Academy of Sciences, that a migration from the Middle East back to Africa occurred approximately 3000 years ago. Journal information: Proceedings of the National Academy of Sciences More information: Ancient west Eurasian ancestry in southern and eastern Africa, Joseph K. Pickrell, PNAS, DOI: 10.1073/pnas.1313787111AbstractThe history of southern Africa involved interactions between indigenous hunter–gatherers and a range of populations that moved into the region. Here we use genome-wide genetic data to show that there are at least two admixture events in the history of Khoisan populations (southern African hunter–gatherers and pastoralists who speak non-Bantu languages with click consonants). One involved populations related to Niger–Congo-speaking African populations, and the other introduced ancestry most closely related to west Eurasian (European or Middle Eastern) populations. We date this latter admixture event to ∼900–1,800 y ago and show that it had the largest demographic impact in Khoisan populations that speak Khoe–Kwadi languages. A similar signal of west Eurasian ancestry is present throughout eastern Africa. In particular, we also find evidence for two admixture events in the history of Kenyan, Tanzanian, and Ethiopian populations, the earlier of which involved populations related to west Eurasians and which we date to ∼2,700–3,300 y ago. We reconstruct the allele frequencies of the putative west Eurasian population in eastern Africa and show that this population is a good proxy for the west Eurasian ancestry in southern Africa. The most parsimonious explanation for these findings is that west Eurasian ancestry entered southern Africa indirectly through eastern Africa.center_img Explore further Citation: Researchers find signs of western Eurasian genes in southern African Khoisan tribes (2014, February 4) retrieved 18 August 2019 from https://phys.org/news/2014-02-western-eurasian-genes-southern-african.html © 2014 Phys.org 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

Supraballs offer a new way to color materials

first_img Play A video shows supraball painted flowers do not change color when the sample is rotated at different angles. Credit: Xiao et al., Sci. Adv. 2017;3: e1701151 Prior research has shown that there are two basic ways to produce color in a material. One is to use materials that have molecules capable of absorbing light, the other is to use materials that cause light to scatter in desired ways using nanostructures. Material scientists have found that using structures to create color has many advantages over those that require absorption, but making them that way has proven to be challenging. In this new effort, the researchers report that they have developed a technique that overcomes those challenges, allowing for the production of colored materials in a way that is fast, simple and scalable.The new technique was inspired by duck and turkey feathers. The team created tiny balls of melanin and then coated them with silica to create structures similar to those found in the bird feathers. Prior research has shown that the spacing between balls of melanin produces different colors. The clear silica coating serves that purpose by forcing the balls farther apart or closer together. The distance is determined by the thickness of the coating—a thick one forces the balls farther apart, while the opposite brings them closer together. Interestingly, observed under a microscope, they are all black. It is only when they are seen from a normal distance that the color emerges. The team notes that changing the size of the balls has no impact on the color produced.The team calls the result of their effort “supraballs.” After creating them and seeing how they worked, they studied them further to understand what was happening. They found that the cores were highly refractive while the shells had a low refractive index, which served to increase reflectance, resulting in colors that were brighter. They note that supraballs could be added directly to paint or plastic base materials to create desired colors and suggest they might also be useful for inks and cosmetic products. Citation: Supraballs offer a new way to color materials (2017, September 18) retrieved 18 August 2019 from https://phys.org/news/2017-09-supraballs-materials.html Play Journal information: Science Advances A way to laser print colors that will not fade using tiny columns Each column represents supraballs made of different sizes of core-shell synthetic melanin nanoparticles. (A) Scanning electron microscope (SEM) images of whole supraball morphologies. (B) High resolution SEM images of top surfaces of supraballs. (C) Cross-sectional transmission electron microscope images of the inner structure of supraballs. Scale bars, (A) 2 micrometers, (B) 500 nanometers and (C) 500 nanometers. Credit: Xiao et al., Sci. Adv. 2017;3: e1701151 An international team of researchers has created a new way to color manufactured materials. In their paper published in the journal Science Advances, the group describes how they created the new coloring technique and why they believe it provides benefits over conventional methods. More information: Ming Xiao et al. Bioinspired bright noniridescent photonic melanin supraballs, Science Advances (2017). DOI: 10.1126/sciadv.1701151AbstractStructural colors enable the creation of a spectrum of nonfading colors without pigments, potentially replacing toxic metal oxides and conjugated organic pigments. However, significant challenges remain to achieve the contrast needed for a complete gamut of colors and a scalable process for industrial application. We demonstrate a feasible solution for producing structural colors inspired by bird feathers. We have designed core-shell nanoparticles using high–refractive index (RI) (~1.74) melanin cores and low-RI (~1.45) silica shells. The design of these nanoparticles was guided by finite-difference time-domain simulations. These nanoparticles were self-assembled using a one-pot reverse emulsion process, which resulted in bright and noniridescent supraballs. With the combination of only two ingredients, synthetic melanin and silica, we can generate a full spectrum of colors. These supraballs could be directly added to paints, plastics, and coatings and also used as ultraviolet-resistant inks or cosmetics. PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen Explore further 2017 Phys.org A photo of a rainbow-like flowers, painted with supraball inks made of five different sizes of core-shell synthetic melanin nanoparticles. Credit: Ming Xiao, University of Akron PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen 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

21 more die of swine flu toll reaches 833

first_imgSwine flu claimed the lives of 21 more people as the toll reached 833 across the country while the number of persons affected by H1N1 virus breached the 14,000 mark.According to Health Ministry figures, the total number of persons who have died of the disease till February 22 is 833 while a total of 14,484 persons has been affected by it across the nation.Health Ministry data on Sunday had showed that 812 people had died due to the disease while 13,688 people had been affected with the H1N1 virus. The maximum toll was reported from Rajasthan with 214 deaths till February 22 out of 4,549 people who were affected by it while 207 people have perished in Gujarat where the number of affected persons stood at 3,107. Also Read – Need to understand why law graduate’s natural choice is not legal profession: CJIIn a stormy start to the Gujarat Assembly budget session on Monday, State Governor O P Kohli had to cut short his address to the House owing to continuous protest and slogan shouting by Opposition Congress members demanding discussion on the swine flu outbreak. Data available with the Health Ministry showed that in Madhya Pradesh 112 people have died due to the disease while 99 have perished in Maharashtra where 1,013 people were affected. In Telangana, 51 people have died while the number of affected persons was 1,316. Health Ministry data showed that eight persons have died in Delhi while 2,241 people are affected by the disease.last_img read more