Month: August 2019

Walls are mirrors with new imaging technique

first_img New laser technology brings perfect focus to medical advances © 2012 Phys.org The paper, published yesterday in Nature Photonics, is authored by Ori Katz, Eran Small and Yaron Silberberg. Prof Silberberg and his colleagues are with the Ultra Fast Optics Group at the Weizmann Institute of Science in Israel. They are being said to have “pushed the limits” of what spatial light modulators (SLMs) can do.SLMs modify the phase of an incoming light beam. Like a series of ocean waves, the waves in light can be slowed down or redirected when they hit scattering materials. The team’s “wavefront shaping” involves using the SLM so that it refocuses at a desired location. Exploiting the angular range in which a single wavefront pattern inverts scattering allows wide-field real-time imaging through a single process.“We show that wavefront-shaping enables wide-field imaging through turbid layers with incoherent illumination, and imaging of occluded objects using light scattered from diffuse walls,” the authors said.“Our results bring wavefront-shaping closer to practical applications and realize the vision of looking through walls and around corners.” This is not the first attempt to explore correcting for scattering, with a number of research efforts in evidence over recent years. In 2010 there was news of a prototype camera that was developed by scientists that can shoot around corners, making use of an ultra-short high-intensity burst of laser light to illuminate a scene.The Weizmann Institute team provides real-time imaging in a different way. As reported in Nature Photonics, the technique is quick, simple and uses natural light rather than lasers. The main power of the technique is said to be that it can work with incoherent light. Unlike past wavefront approaches, this technique does not require a coherent source, interferometric detection, raster scanning or off-line computational reconstruction. Earth-based astronomy and deep tissue imaging are two relevant areas that could make use of the study’s findings, as both astronomy and deep tissue imaging are challenged by scattering and dense materials. Talking about future applications, principal investigator Silberberg said, “Our technique for imaging through scattering layers may allow that study of previously inaccessible biological samples by optical imaging, e.g., imaging through thin egg shells for studying embryonic development.” Silberberg further explained what could make a difference. “If you want to look to see an embryo developing inside an egg but the eggshell scatters everything, or you want to look through the skin, scattering is the main enemy there, and time-of-flight is not a good solution.” He was referring to the “time-of-flight” approach with a laser-based camera. He envisions that the primary use for their technique will be in biological and medical studies. More information: Looking around corners and through thin turbid layers in real time with scattered incoherent light, Nature Photonics (2012) doi:10.1038/nphoton.2012.150 (Preprint is available on Arxiv)AbstractImaging with optical resolution through turbid media is a long sought-after goal with important applications in deep tissue imaging. Although extensively studied, this goal was considered impractical until recently. Adaptive-optics techniques, which can correct weak aberrations, are inadequate for turbid samples, where light is scattered to complex speckle patterns with a number of modes greatly exceeding the number of degrees of control. This conception changed after the demonstration of coherent focusing through turbid media by wavefront-shaping, using spatial light modulators. Here, we show that wavefront-shaping enables wide-field imaging through turbid layers with incoherent illumination, and imaging of occluded objects using light scattered from diffuse walls. In contrast to the recently introduced schemes for imaging through turbid media, our technique does not require coherent sources, interferometric detection, raster-scanning or off-line reconstruction. Our results bring wavefront-shaping closer to practical applications and realize the vision of looking through ‘walls’ and around corners. (Phys.org) — A child’s dream wanting to come true: putting on a magic cape to see around corners and through walls, solving mysteries and catching criminals. Scientists, meanwhile, are achieving the same optical powers with knowledge and labs if not capes. A study published yesterday, “Looking around corners and through thin turbid layers in real time with scattered incoherent light,” is attracting much attention in its description of the technique, using a spatial light modulator to undo the scattering that makes objects opaque or non-reflecting. Their technique allows real-time imaging through opaque materials and around highly scattering optical diffusers. Journal information: Nature Photonics Citation: Walls are mirrors with new imaging technique (2012, July 16) retrieved 18 August 2019 from https://phys.org/news/2012-07-walls-mirrors-imaging-technique.html 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

Physicists discuss quantum pigeonhole principle

first_img More information: arxiv.org/pdf/1407.3194v1.pdfarxiv.org/abs/1407.3194 Explore further Science writers reporting on the physicists’ findings heard resonance with that other blogger-comment favorite, Schrödinger’s cat. They suggested that those mulling over counterintuitive implications of quantum physics now have one more animal-related paradox to think about, in the form of pigeons, if any, found in pigeonholes. Physics World on Friday referred to “paradoxical pigeons” as the latest quantum conundrum. Scientists identified the paradox involving quantum pigeons; specifically, they have posed their findings on what the team calls the “quantum-pigeonhole effect.” According to the team, when you put three pigeons in two pigeonholes, it is possible for none of the pigeons to share a hole. They found instances when three quantum particles, they wrote, put in two boxes “yet no two particple are in the same box.”The team from California and colleagues in Israel, Italy and the UK are authors of the paper, “The quantum pigeonhole principle and the nature of quantum correlations,” by Y. Aharonov, F. Colombo, S. Popescu, I. Sabadini, D.C.Struppa, and J. Tollaksen. The research is described on the arXiv preprint server.”It’s one of those things that seem to be impossible,” said co-author Jeff Tollaksen, physics professor at Chapman University, in Physics World, but it is a consequence of quantum mechanics. “In conclusion,” said the authors,” we presented a new quantum effect that requires us to revisit some of the most basic notions of quantum physics—the notions of separability, of correlations and of interactions.”Marcus Woo, writing in Physics World on Friday, said, “They reckon that the effect will arise when an observer makes a sequence of measurements while trying to fit three particles in two boxes. First, you make an initial, “pre-selection” measurement of the locations of the particles. Next, you can perform an intermediate measurement to see whether two particles share a box. Finally, you make a final, “post-selection” measurement of the locations. You can make the pre-selection and post-selection measurements such that they are completely independent. In the intermediate step, you can make what’s called a weak measurement to look at all three particles simultaneously. And when you do, it turns out that no two particles share a box. Credit: Wikipedia © 2014 Phys.org Researchers find nondestructive method to study quantum wave systems The pigeonhole principle: “If you put three pigeons in two pigeonholes at least two of the pigeons end up in the same hole.” So where’s the argument? Physicists say there is an important argument. While the principle captures the very essence of counting, the investigators said that they showed that in quantum mechanics it is not true. Citation: Physicists discuss quantum pigeonhole principle (2014, July 26) retrieved 18 August 2019 from https://phys.org/news/2014-07-physicists-discuss-quantum-pigeonhole-principle.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

How the brain combines information across sensory modalities

first_img Explore further Binocular rivalry occurs when the two eyes view dissimilar ocular stimuli, and interocular competition replaces stable binocular single vision. When the left and right eye are in disagreement, the brain resolves the conflict via compromise, alternating visual awareness between the two viewpoints over time—the input from one eye will be suppressed from consciousness while the other becomes dominant. This rivalry phenomenon offers researchers the opportunity to study the inferential nature of perception and the brain’s apparent tendency to apply additional sensory context when presented with confusing visual input.Musicians are ideal subjects for studying the congruence between abstract visual representations because they are familiar with symbolic musical notation, and can therefore experience melodic structure through both sound and vision. The researchers designed an experiment in which a group of both musicians and nonmusicians were subjected to a conventional binocular rivalry task in which they pressed buttons to track alternating periods of dominance and suppression between dissimilar monocular displays—one eye saw a musical score scrolling through the display; the other eye saw a vertical, drifting grating. Participants tracked their alternations in perception in one of three audiovisual conditions: while listening to a melody that was congruent with the score; while listening to a melody that was incongruent with the score; or while not listening to any sound at all. 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)—Visual information is dense, and researchers have long theorized that when visual stimuli are confusing or ambiguous, the brain must apply additional contextual information in order to interpret it. A group of Korean researchers became interested in one source of visual confusion called binocular rivalry as a means of studying how the brain provides additional context to confusing visual information. They have published the results of their study in the Proceedings of the National Academy of Sciences. As the authors write, these results add to the growing evidence that the process of sensory combination is a form of probabilistic inference “with dynamic weightings of different sources of information being governed by their reliability and likelihood.” Additionally, the bisensory congruence observed in the participants with musical training only occurred when the musical score was perceptually dominant, not when it was being suppressed from awareness by the image of the grate in the opposite eye. “Taken together, these results demonstrate robust audiovisual interaction based on high-level, symbolic representations and its predictive influence on perceptual dynamics during binocular rivalry,” the authors write. More information: “Melodic sound enhances visual awareness of congruent musical notes, but only if you can read music.” PNAS 2015 ; published ahead of print June 15, 2015, DOI: 10.1073/pnas.1509529112AbstractPredictive influences of auditory information on resolution of visual competition were investigated using music, whose visual symbolic notation is familiar only to those with musical training. Results from two experiments using different experimental paradigms revealed that melodic congruence between what is seen and what is heard impacts perceptual dynamics during binocular rivalry. This bisensory interaction was observed only when the musical score was perceptually dominant, not when it was suppressed from awareness, and it was observed only in people who could read music. Results from two ancillary experiments showed that this effect of congruence cannot be explained by differential patterns of eye movements or by differential response sluggishness associated with congruent score/melody combinations. Taken together, these results demonstrate robust audiovisual interaction based on high-level, symbolic representations and its predictive influence on perceptual dynamics during binocular rivalry. The video shows examples of the musical scores and melodies used to determine that the brain can use the abstract information in a musical score to interpret what it is seeing. Credit: Blake Laboratory, Vanderbilt University ResultsIn the experiment, musical scores in rivalry enjoyed significantly greater predominance than the image of the drifting grate among the participants who were able to read music. Predominance was not significantly different between the grate and the musical score for participants who could not read music.The researchers conclude that visual awareness during states of interocular competition is influenced by nonvisual information. They theorize that musical training might play a role in the development of unusually strong connections between the brain’s perception and action systems. They further attribute the multisensory interactions observed in the study to information combinations across different sensory modalities, rather than to any sensory-neural convergence of auditory and visual signals. last_img read more

Topiwalleh in town

first_imgThat bling in their outfits, the multicolored Nehruvian topis and the high impact folk rock performance are what make Swarathama stand out. Coming from Bengaluru, the band retains its roots by playing E Bhoomi, their Kannada composition, wherever they go. Will begin with the most striking feature of your band- the topis. Do these signify any ideology behind the band?Well, our topis have a story to them. These are so significant that our second album in 2012 was named Topiwalleh. We used to don topis for our performances even before this album. These were not in vogue and we wanted to give them our own spin. Also Read – ‘Playing Jojo was emotionally exhausting’We are a set of liberal people, with different ideologies. So, the Nehruvian topis do not stand for our ideology. Incidentally, the guy who makes our topis comes from a lineage where his forefathers made the same for Indian freedom fighters.Q. And do people connect to the Kannada singing band?It’s not only Kannada music, that  we play. It’s just E-bhoomi that makes it to all our performances and then there is Nane-davi( My own way) and Jambha (pride) that people like. Also Read – Leslie doing new comedy special with NetflixYou wouldn’t believe the kind of response our topis and music elicit. It is a wonderful feeling to see people reciprocate by wearing the topis during our performances. For our international audience, we try and explain our lyrics to put things into perspective. In return, when music lovers in UK come wearing our topis, it is sheer delight to play for them.Q. That’s amazing! And it’s equally amazing to know about your social campaigns. Do you feel some sense of social responsibility as a band? We started ‘Action replay’ somewhere during our initial years as a band. The idea was to do a free-of-cost gig against all of our performances. I wish we could actually do one free gig even now but it is just not possible. But we try and take our music to villages, small towns and places other than the posh cafes of metropolitans. Q. What sort of response does a folk rock band get in smaller towns of India?People have a set perception about bands- crazy and freakish college kids with an affinity to drugs seem to be their idea of music band followers. We have, in our own way, changed that perception to an extent. Q. It is indeed a huge change. What are you planning next?Thank you. We have started working on the tunes of our third album. In a year’s time, we should be able to come out with it. Apart from that, we want to collaborate and jam with other artistes to produce some soul enriching music.last_img read more

Saluting quality

first_imgAnil Kumar Sharma, CMD, Amrapali Group and President, CREDAI-NCR received the Real Estate Tycoon Indi award for his outstanding contribution to the realty sector. The award was presented by Rt. Hon. Baroness Sandip Verma (Minister for Energy and Climate Change, U.K.) at a ceremony held in London. The Indo- British Partnership ceremony was graced by the presence of Rt. Hon. Lord Swraj Paul, Lord Dolar Popat of Harrow, Lord Ahmad of Wimbledon (UK Parliament), Lord Md. Sheikh and Lord Diljit Rana. Event also saw the presence of Deputy High Commissioner of India to UK, Dr. Varinder Paul. The leaders enlightened the diaspora about the Indo-British relation going strong and how could it go stronger.last_img read more

The booked Capital

first_imgAs Valentine’s Day is just around the corner, love-struck couples must be busy deciding their dating places for the special day. The search gets confined to restaurants, malls and other such places that claim special offers on the cupid’s day. Well, this time you can give a break to your normal dates and can celebrate the day with your loved ones in the company of books!Yes, you heard it right. The New Delhi World Book Fair 2015 is commencing on February 14 at Pragati Maidan. And if your loved one is a cricket fan, you can give him/her the best Valentine Day gift ever. Virender Sehwag is expected to pay a visit there and what better gift to a cricket fan than a meeting with the legend himself. Also Read – ‘Playing Jojo was emotionally exhausting’As far as the ‘book lovers’,  are concerned this year the fair will mark over 1050 participants from around the globe. But the one thing to watch out for is its theme presentation based on North East. Whenever someone talks about the Seven Sisters, its breathtaking beauty flits into our mind. From people, languages, cultures, traditions to cuisines, the land possesses enormous diversity. Taking a leaf out of its literary diversity, the fair will present Suryodaya: Emerging Voices from North East India that focuses on the rich corpus of writing from the region, the land and its people. Also Read – Leslie doing new comedy special with NetflixSingapore which is the Guest of Honour country will be participating with the 43-member strong delegation of publisher, authors and scholars. South Korea being the focus country will be participating with a 12-member delegation. Over 200 Korean books will be released during the fair. National Book Trust will also be releasing around 25 books over the period of the fair. This year the fair has introduced three initiatives that include CEO Speak, Rights Table and Author’s Corner. More than 100 CEOs and dignitaries from the industry will discuss book-trade related issues at the CEOSpeak Publishers Forum on February 15. The Right Table is a two-day event (February 16 -17) that will offer a B2B match making session between publishers. A joint venture of NBT and ITPO, Delhi World Book Fair 2015 will be inaugurated by Smriti Zubin Irani, Union Minister of Human Resource Development in the presence of author Narendra Kohli. Lim Thuan Kuan, High Commissioner of Singapore to India. Apart from Singapore and South Korea, 28 other countries like – France, Nepal, Pakistan, Germany, Japan, USA among others will be displaying their books in the Foreign Pavilion. For children, apart from the several activities, their pavilion will be organising various interactive sessions with the authors, illustrators and storytellers.Like previous year, this year too eminent authors and literary personalities will be holding interactive sessions and interactions with the visitors at various author corners. Different art and cultural workshops, creative writing/drawing competitions for children and cultural programmes have been organised that will add on to the festive mood all throughout the book fair. So, do pay a visit to the place, doesn’t matter if you are a book lover or not!last_img read more

Govt to back cos that face US sanctions for investing in Iran

first_imgIndia will protect economic interest of its oil companies from being impacted in the eventuality of US sanctions against them for investing in Iran, Petroleum Minister Dharmendra Pradhan said on Monday.Pradhan made the comments after Government Accountability Office (GAO) of US named Oil and Natural Gas Corp (ONGC), Indian Oil Corp (IOC) and Oil India Ltd (OIL) along with two Chinese firms for having energy ties with Iran, an act for which it can impose sanctions against them. Also Read – I-T issues 17-point checklist to trace unaccounted DeMO cash“India will take its own stand, independent diplomatic stand on the issue,” he said. “Certainly economic interest of our companies and country will be priority.” He, however, refused to elaborate saying such issues cannot be discussed through media. The US Iran Sanctions Act provides for steps against persons, including foreign firms, investing more than $20 million in Iran’s energy sector in any 12-month period.According to GAO, the US has not imposed sanctions on any firm for their Iran energy ties since 1998. The US and its allies have pursued the sanctions route to isolate Iran over its alleged nuclear programme. Also Read – Lanka launches ambitious tourism programme to woo Indian touristsThe three firms have been named for their stake in the Farsi offshore block in Iran. “Looking at the diplomatic complexity of the whole issue, we will look at ways how our companies wont be affected by any adverse situation,” Pradhan said. ONGC, IOC and OIL have been named for having 40 per cent, 40 per cent and 20 per cent interest respectively in the Farsi block.All the three firms gave similar response to US GAO saying the “exploration contract (for Farsi block) expired in 2009” and that they had “not carried out any activity after 2007 in the Farsi Block”.OVL, IOC and OIL explored for oil and gas in Iran’s Farsi block and proposed investing $5.5 billion to produce gas from the 21.68 trillion cubic foot discovery they made in the offshore area located near the Saudi Arabian border.They, however, haven’t invested in the development due to differences over the contract with the Iranian government.last_img read more