A step closer to a practical atom laser

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. Research team supersizes ‘quantum squeezing’ to measure ultrasmall motion Explore further “But there is an uncertainty, since the number passing fluctuates. When the fluctuations are larger than the effect you are looking for, precise measurements are more difficult. For example, if the fluctuations in your signal due to underlying quantum uncertainty is 50 photons per second, and the effect you’re looking for change the number you’re measuring by 10 per second, you won’t see the effect. What we have done is try to get rid of some of that uncertainty.”Johnsson, a scientist at The Australian National University in Canberra, and his coauthor, Simon Haine, believe that one way to reduce the uncertainty associated with measurements in atom lasers is to perform a technique known as “squeezing.” However, creating a squeezing effect can be difficult. Johnsson and Haine have created models to show a way to get a squeezing effect though self-interaction of atoms using technology that exists now. Their findings can be found in “Generating Squeezing in an Atom Laser through Self-Interaction,” which is published in Physical Review Letters.“An atom laser makes use of atoms with special quantum properties rather the photons employed by a normal optical laser,” Johnsson says. “This potentially allows for much more precise measurements, as well as measurements of effects that cannot be seen by an optical laser. Many of the things we do now with optical lasers, we hope to be able to do with atom lasers.” “Right now it is fair to say that an atom laser is more of a research tool,” Johnsson concedes. “But in the 1960s, when optical lasers were first being used, the case was the same. But now there are all sorts of applications. We believe our work will lead to interesting applications for atom lasers.”And one of the steps toward that realization is discovering that squeezing can provide a steadier stream of atoms. “Squeezing allows you to shuffle uncertainty from one quality, such as velocity or motion, to another. You can’t measure both as accurately as you want,” Johnsson explains. “With squeezing, if you want to measure how many particles are passing at a given time, you can measure that more accurately at the expense of making something else — something you don’t care about — less accurate.”Johnsson and Haine’s idea was to find a simpler way to make the squeezing happen. Other scientists have tried to use squeezing with optical lasers, but it is very difficult. “The different properties of atoms actually makes it easier,” Johnsson says. “Photons in a light beam don’t interact with each other. Atoms are constantly bumping into each other. They naturally, through interaction, create the squeezing effect. We were surprised at how easy it works.”But that is where the difficulty begins. “Even though we don’t have to do anything to facilitate the squeezing,” Johnsson points out, “if you let it go on too long, the effect will break down. You have to be able to manipulate them in order to get the atoms in the beam to interact just enough.” The next problem, he continues, will be actually measuring the squeezing effect. “We’ve come up with a scheme that allows us to create an atom laser for precise measurements, and the experiment should be easy to set up. But we need a detector.” Johnsson explains that detecting individual atoms is difficult, and that the biggest challenge will be counting them in order to verify the squeezing effect. He remains optimistic, though. “This is one of the major things the experimentalists in our group want to do in the next couple of years. We could be closer to a better atom laser.”Copyright 2007 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.center_img “When doing precise measurements of any kind, it is important to be able to count something, such as photons coming by at any given time,” Mattias Johnsson tells PhysOrg.com. Citation: A step closer to a practical atom laser (2007, July 19) retrieved 18 August 2019 from https://phys.org/news/2007-07-closer-atom-laser.htmllast_img read more

Linguists to rethink reason for short words

first_img A link between the length of words and how frequently they are used was first proposed in 1935 by George Kingsley Zipf, a Harvard University linguist and philologist. Zipf’s idea was that people would tend to shorten words they used often, to save time in writing and speaking. The relationship seems intuitive and it seems to apply to many languages with short words such as “the”, “a”, “to”, “and”, “so” (and equivalents in other languages) being frequently used. Researchers at the Massachusetts Institute of Technology (MIT), led by Steven Piantadosi, tested the Zipf relationship by analysing word use in 11 European languages. They analyzed digitized texts for correlations between words by counting how often all pairs of words occurred in sequence. This information was then used to estimate the probability of words occurring after given previous words or sequences of words. They made the assumption that the more predictable a word is, the less information it conveys, and estimated the information content from information theory, which says the information content is proportional to the negative logarithm of the probability of a word occurring.Piantadosi said if the word length is directly related to information content this would make the transmission of information through language more efficient and also make speech and written texts easier to understand. This is because shorter words, carrying less information, would be scattered through the speech, essentially “smoothing out” the information density and delivering the important information at a steady rate.The studies suggest that the short words are in fact the least informative and most predictable words rather than the most often used, and that word length is more closely related to the information the words contain.The paper is soon to be published in the Proceedings of the National Academy of Sciences (PNAS). Steven Piantadosi belongs to the PhD program with MIT’s Department of Brain and Cognitive Sciences. As long as original version still available, tweaking Twain is OK, professor says Explore further © 2010 PhysOrg.com Citation: Linguists to re-think reason for short words (2011, January 25) retrieved 18 August 2019 from https://phys.org/news/2011-01-linguists-re-think-short-words.htmlcenter_img (PhysOrg.com) — Linguists have thought for many years the length of words is related to the frequency of use, with short words used more often than long ones. Now researchers in the US have shown the length is more closely related to the amount of information the words carry than their frequency of use. More information: Piantadosi, S. T., et al. Proceedings of the National Academy of Sciences (2011). PNAS paper will appear online at dx.doi.org/10.1073/pnas.1012551108 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

Paleoecologists suggest mass extinction due to huge methane release

first_img Global warming led to atmospheric hydrogen sulfide and permian extinction © 2010 PhysOrg.com Explore further (PhysOrg.com) — Micha Ruhl and colleagues from the University of Copenhagen’s Nordic Center for Earth Evolution have published a paper in Science where they contend that the mass extinction that occurred at the end of the Triassic period, was due to a “sudden” increase in the amount of methane in the atmosphere due to the effects of global warning that resulted from the spewing of carbon dioxide from volcanoes. Citation: Paleoecologists suggest mass extinction due to huge methane release (2011, July 22) retrieved 18 August 2019 from https://phys.org/news/2011-07-paleoecologists-mass-extinction-due-huge.html More information: Atmospheric Carbon Injection Linked to End-Triassic Mass Extinction, Science 22 July 2011: Vol. 333 no. 6041 pp. 430-434 DOI:10.1126/science.1204255ABSTRACTThe end-Triassic mass extinction (~201.4 million years ago), marked by terrestrial ecosystem turnover and up to ~50% loss in marine biodiversity, has been attributed to intensified volcanic activity during the break-up of Pangaea. Here, we present compound-specific carbon-isotope data of long-chain n-alkanes derived from waxes of land plants, showing a ~8.5 per mil negative excursion, coincident with the extinction interval. These data indicate strong carbon-13 depletion of the end-Triassic atmosphere, within only 10,000 to 20,000 years. The magnitude and rate of this carbon-cycle disruption can be explained by the injection of at least ~12 × 103 gigatons of isotopically depleted carbon as methane into the atmosphere. Concurrent vegetation changes reflect strong warming and an enhanced hydrological cycle. Hence, end-Triassic events are robustly linked to methane-derived massive carbon release and associated climate change. Prior to this research, most scientists have believed that the sudden extinction of nearly half of all life forms on the planet was due solely to the emissions from volcanic eruptions that were occurring in what was to become the Atlantic Ocean. Ruhl et al contend that instead, what happened, was that the small amount of atmospheric heating that occurred due to the exhaust from the volcanoes, caused the oceans to warm as well, leading to the melting of ice crystals at the bottom of the sea that were holding on to methane created by the millions of years of decomposing sea life. When the ice crystals melted, methane was released, which in turn caused the planet to warm even more, which led to more methane release in a chain reaction, that Ruhl says, was the real reason for the mass extinction that led to the next phase in world history, the rise of dinosaurs. Ruhl and his team base their assertions on studies they’ve made of the isotopes of carbon in plants (found in what is now the Austrian Alps) that existed during the period before the mass extinction. In so doing they found two different types of carbons and the molecules that were produced during that time frame. After extensive calculations, Ruhl and his team came to the conclusion that some 12,000 gigatons of methane would have had to have been pumped into the atmosphere to account for the differences in the isotopes; something the team believes could only have happened if the methane were to come from the sea floor.This new research, though dire sounding, may or may not have implications for modern Earth. While it is true that humans have pumped significant amounts of carbon into the atmosphere, amounts that are approaching what Ruhl and his team say led to the earlier methane release, it doesn’t necessarily mean we are on the same path, because as Ruhl points out, things are much different today, the very structure of the planet has changed so much that it would be impossible to transfer what might have been learned about events in Earth’s history 200 million years ago, to what is going on today. This wide angle view of the Earth is centered on the Atlantic Ocean between South America and Africa. 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

Boston Dynamics Atlas shows balance WildCat sprints untethered w Video

first_img © 2013 Phys.org DARPA’s ATLAS robot unveiled (w/ Video) The feat is a tribute to the company’s control system for the robot. The demo shows how Atlas can stay upright using kinematic and load data from its sensors. Commenting on his reaction to seeing Atlas stay balanced despite being hit by the ball, Noel Sharkey, professor of artificial intelligence and robotics at the University of Sheffield, told the BBC it was “an astonishing achievement” and “remarkable feat.” Next on the engineering agenda is to give Atlas an articulated head with stereo cameras and a laser range finder, along with sensate hands capable of using tools. More information: www.bostondynamics.com/index.html Legged Squad Support System (LS3) is a four-legged robot designed to travel 20 miles on rough terrain carrying 400 lbs of load. The video shows field testing at Twentynine Palms, CA. Testing includes rough-terrain mobility, endurance, visually guided following, GPS guided maneuver, and overall reliability. LS3 is being developed by Boston Dynamics with funding from DARPA and the US Marine Corps. The company’s history dates back to when it was a spinoff from the Massachusetts Institute of Technology, where Marc Raibert and colleagues developed animal-inspired robots. They founded the company in 1992. 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 Atlas is part of the DARPA Robotics Challenge Program. The robot is tethered, powered from an off-board, electric power supply. Atlas’ reason for being is to serve as a humanoid robot that will be capable enough to move in outdoor, rough terrain. The limbs need to perform well, to be able to lift, carry and manipulate in rough environments. Atlas was unveiled in July at the company, as a robot that can respond to dangerous emergencies.The video shows the Atlas robot now on rough terrain walking with bent knees and arms stretched, on rubble and rocks, maintaining its balance as it moves along. In another scene, a ball is trying to knock it over as Atlas stands on one foot, maintaining its balance even while standing on one leg and being hit by the ball from the side. WildCat is a four-legged robot being developed to run fast on all types of terrain. So far WildCat has run at about 16 mph on flat terrain using bounding and galloping gaits. The video shows WildCat’s best performance so far. This month, Boston Dynamics also posted a video of its WildCat robot, funded by DARPA and developed for emergency response and aid scenarios, in a public outing beyond and free from indoor treadmills. The big news about WildCat is that, unlike its robotic cousin Cheetah, this quadruped is untethered. Cheetah drew attention for its speed; the robot could run at 28 miles per hour but that was on a treadmill indoors tethered to a power supply. WildCat can sprint and gallop unrestrained at 16 miles per hour outside of the lab. The video shows its capabilities. (Phys.org) —Boston Dynamics, the Waltham, Massachusetts robotics company that receives funds from the Defense Advanced Research Projects Agency (DARPA), is making more video news. Whether the company turns out videos of intros and updates of robots such as BigDog, or Petman, or Cheetah, its animal- and human-inspired robots promptly make the rounds of dozens of news sites and blogs. The company has made these robots interesting works in progress, as we see them, from development phase to phase, advancing in balance, agility, speed and strength. This month’s video hits from Boston Dynamics show the company’s two tests, for its bipedal Atlas and its quadruped WildCat. Citation: Boston Dynamics: Atlas shows balance; WildCat sprints untethered (w/ Video) (2013, October 8) retrieved 18 August 2019 from https://phys.org/news/2013-10-boston-dynamics-atlas-wildcat-sprints.htmllast_img read more

Pencil drawing of a sensor actually is a sensor

first_img More information: Ting-Kuo Kang. “Tunable piezoresistive sensors based on pencil-on-paper.” Applied Physics Letters 104, 073117 (2014). DOI: 10.1063/1.4866440 Using graphite pencils to draw on regular paper, researchers can make some very inexpensive piezoresistive (PZR) sensors. Due to the piezoresistive effect, a sensor’s resistance changes under an applied strain, allowing it to sense mechanical stress and pressure. The first of these pencil-on-paper PZR sensors was fabricated a few years ago as an alternative to silicon PZR sensors, which are costly and require sophisticated fabrication processes. Explore further © 2014 Phys.org. All rights reserved. A pencil-on-paper PZR sensor with an integrated circuit for measuring the sensor’s voltage change under an applied stress. Credit: Kang ©2014 AIP Publishing Journal information: Applied Physics Letters “PZR sensors can be drawn by anyone with a graphite pencil and paper,” Ting-Kuo Kang, a researcher at Cheng Shiu University in Kaohsiung City, Taiwan, told Phys.org. Although graphite PZR sensors are much easier to fabricate than silicon ones, they generally are not as sensitive because graphite’s electrical properties are not as good as those of silicon. In a new study published in Applied Physics Letters, Kang has further investigated the underlying mechanisms of graphite’s PZR properties and improved the sensitivity of graphite-based PZR sensors.PZR sensitivity is characterized by the gauge factor (GF), which is defined as the ratio of the change in electrical resistance to the applied strain. While silicon PZR sensors have GFs above 100, the GFs of graphite PZR sensors are in the single digits.In experiments, Kang used 12 different grades of graphite pencils to draw U-shaped PZR sensors on paper. The pencils are graded by their ratio of graphite to clay. Grades ranged from 9B to 2H, where H denotes the hardness caused by the pencil’s clay content, and B denotes the blackness due to the graphite content. center_img The sensors were drawn on paper that was placed on an electric scale in order to measure and maintain a consistent drawing force for each pencil-drawn sensor. The drawings were then glued on printed circuit board (PCB) strips, and a strain gauge mounted on each PCB strip. Then Kang applied cycles of stress to the sensor using a four-point bending technique, and measured the sensor’s voltage change under the applied stress through an electric circuit. He found that different pencil grades produce different GF values, and therefore different PZR sensitivities. Specifically, the higher the ratio of clay to graphite, the greater the change in resistance under the applied stress, and the greater the GF. Kang explains that these differences can be attributed to variations in the initial tunneling distances between neighboring graphite, with an increase in tunneling distance corresponding to an increase in GF.”The graphite tunneling effect is from one graphite through the insulator of clay to another graphite,” Kang said. “The tunneling structure looks like a metal-insulator-metal.”Currently, PZR sensors made of silicon are used as pressure sensors, accelerometers, and biological sensors, among other applications. As the sensitivity of pencil-drawn graphite PZR sensors continues to improve, they may also be used for these applications. Kang also plans to develop flexible and disposable sensor applications using pencil-on-paper techniques. Citation: Pencil drawing of a sensor actually is a sensor (2014, February 28) retrieved 18 August 2019 from https://phys.org/news/2014-02-pencil-sensor.html Relationship between relative resistance and applied stress for drawings with different grades of pencils. The differences stem from variations in the initial tunneling distances between neighboring graphite. Credit: Kang ©2014 AIP Publishing Noting tech needs, mining companies seek graphite 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

MIT professor creates reality TV series of his daily life

first_img Major cities must unite against climate change: Paris mayor © 2017 Phys.org Citation: MIT professor creates reality TV series of his daily life (2017, March 27) retrieved 18 August 2019 from https://phys.org/news/2017-03-mit-professor-reality-tv-series.html Shot from In My Shoes. Credit: Cesar Hidalgo (Phys.org)—”What if the Kardashians were physicists?” asks César Hidalgo, an associate professor at MIT and director of the Collective Learning group at the MIT Media Lab.center_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. Fortunately they’re not, but that odd-sounding blend might be the best way to imagine Hidalgo’s new project: a video series called “In My Shoes” that documents his professional life as a researcher and his personal life as a husband and father of a young daughter. The final product—eight episodes ranging in length from 10 to 20 minutes—can be viewed at https://www.inmyshoes.info. “The goal of the series is to help show younger people considering an academic career what the day-to-day of the life of a scholar is like,” he said. “Personally, I think that this would have been very useful to me 20 years ago, when I was considering an academic career but had no role models in Chile.”Hidalgo self-recorded his life over the course of three months in 2016. During that time, he traveled extensively—from Boston to Washington, D.C.; Saudi Arabia; Switzerland; Portland; Monterrey; and Paris. One of the major projects that Hidalgo was working on at the time was DataUSA, a website that presents all kinds of data (economic, demographic, health, education, housing, etc.) in a visual, rapidly digestible way. It’s intended to provide information for policymakers, business owners, students, and job-seekers.The video series, however, is not intended to inform us of the technical details of such projects. Instead we get an inside look at what’s it like to actually be the person developing and sharing these projects, complete with all of the thoughts and concerns that any ordinary person would have. Hidalgo’s narration is thoughtful, entertaining, modest, and—when it comes to what jet lag feels like after 24 hours of travel—painfully sincere. It’s a unique and personal perspective of the academic life that breaks down the traditional stereotypes—especially as we learn that even MIT professors find it challenging to dress a two-year-old in the morning. Explore furtherlast_img read more

Study suggests darkcolored wing feathers may help birds fly more efficiently

first_img Explore further Credit: CC0 Public Domain Flying without wings: Losing feathers has a detrimental effect on migrating birds Humans have been studying birds and other flying creatures likely since the time they could think. In a new study, researchers wondered if the color of a bird had any impact on flying efficiency. To find out, they collected several stuffed samples and brought them to their lab for study.The experiments consisted of putting stuffed wings in a wind tunnel, heating them with infrared lights and then testing them to see what happened. They were most interested in soaring birds such as back-blacked gulls, gannets and osprey. They tested samples of each under various wind conditions to see if wing color had an impact on flying efficiency. Notably, soaring birds can at times gain altitude without even flapping their wings due to undercurrents.The researchers report that dark feathers grew hotter than lighter colored feathers and they also gained heat faster than lighter colors. But it was birds that had white or light-colored wing feathers near their bodies and dark or black feathers on the rest of their wings that saw a real benefit. The researchers found temperature differences as great as nine degrees between black and white feathers on the same wings—enough to create a convection current in the air just over the wing, moving from the bird’s body outward along the wing. They noted that this boosted airflow, which, they assumed, made flying more efficient. The researchers plan to continue studying this effect in birds, hoping to determine just how much of an increase in lift the birds actually get from their color differences—and if there are differences in drag. Citation: Study suggests dark-colored wing feathers may help birds fly more efficiently (2019, July 25) retrieved 18 August 2019 from https://phys.org/news/2019-07-dark-colored-wing-feathers-birds-efficiently.html More information: Svana Rogalla et al. Hot wings: thermal impacts of wing coloration on surface temperature during bird flight, Journal of The Royal Society Interface (2019). DOI: 10.1098/rsif.2019.0032center_img © 2019 Science X Network 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 team of researchers at the University of Ghent has found evidence that suggests birds with white wing feathers close to the body and black wing tips get increased lift from their wing colors. In their paper published in Journal of the Royal Society Interface, the group describes their study of wing color in several species of birds and what they found. Journal information: Journal of the Royal Society Interfacelast_img read more

Capturing more than 50 shades of a woman

There is no better muse to an artist than a woman. Her many shades and complexities make for excellent art work and Italian artist Patrizia Maimouna Guerresi’s exhibition Inner Space explores women who have been marginalised by society. But that’s not all the exhibition is about. ‘The images I will present at the exhibition are timeless, rigorous, and classic. They do not depict ancient India or a new India in constant development. They are the inner representations of a greater Indian spirituality,’ said Guerresi. Also Read – ‘Playing Jojo was emotionally exhausting’The artiste also said that through her work she wanted to highlight the many different societies co-existing in unity.Guerresi is an Italian photographer, sculptor and video installation artiste who has been involved for over 20 years in empowering women and bringing together individuals and cultures in an appreciation for a context of shared humanity far beyond the borders.After exhibiting across Europe and Middle-East, she will be exhibiting her first solo exhibition in India with Tasveer. Also Read – Leslie doing new comedy special with NetflixHer art is inspired by her own personal experience and the cultural contexts she has witnessed. The universal myths, the sacred realm, and the female condition, all of which are the vital expressions of the human form, form an intergral part of her work. Through her photography and videography of silent, austere and veiled women in domestic scenes and individual poses, she attempts not only to show and express the angst but sometimes provokes a strong reaction. Her work can be termed both metaphorical and also thought provoking.Women dressed in white, enveloped in chadors, [full-body-length semicircle of fabric that is open down the front] fixed within their own tradition and isolated from and by it in the contemporary world is yet another example of her fascinating work that will be displayed. If you feel you need to understand the many complexities of women, then you should definitely be at the exhibition.DETAILAt: Italian Cultural Centre, 50-E, Chandragupta Marg, Chanakya Puri, New DelhiWhen: 18 TO 27 October Timings: 11 am – 7 pm read more

Acting up on city stage

first_imgFigure theatre or puppet theatre as it is commonly known in Europe has been quite popular in Japan as object theatre. This figure art is now coming to five major cities in India and is being brought by the Japan Foundation. The Noriyuki Sawa Puppet Theatre India Tour 2012 will showcase performances on Japanese folktales. Object theatre is a  new form of theatre where people and puppets perform together on stage with equal stage presence.  Noriyuki Sawa is a contemporary puppet theatre performer who studied figure theatre at the Czech national Academy of Performing Arts in Prague and  continued to perform in collaboration with numerous leading theatres such as DRAK from his base in the Czech Republic. Some of the performances that will be enacted in the Capital includes The Legend of Forest, Star, Fish, Sky and seed. So we say its time for the Capital to gear up for a new kind of theatre.DETAILAt: Chinmaya Mission, Lodhi Road When: 10 and 11December Timings: 6.30 pmlast_img read more

Is NATO close to winding up long Afghan innings

first_imgThe American and British flags were lowered and folded up for the final time at the regional headquarters of the international military, 13 years after the toppling of the Taliban’s radical Islamist regime launched America’s longest war.  The timing of the troops’ withdrawal from the base in the strategic province of Helmand was not released for security reasons. However, according to earlier reports, the ‘longest war in American history’ will last at least another decade, as per the conditions of a garrisoning deal for US forces signed by the new Afghanistan government late last month.The deal guarantees that US and NATO troops will not have to withdraw by year’s end, and permits their stay ‘until the end of 2024 and beyond.’ Also Read – Need to understand why law graduate’s natural choice is not legal profession: CJIBut the current wrap-ups hold high symbolic currency. Camp Leatherneck is the largest US base to be handed over to Afghan control as the coalition ends its combat mission at the end of the year, leaving most of the fight against a resilient Taliban insurgency to Afghan army and police.  British forces transferred the adjacent Camp Bastion at the same time. Once a teeming compound of some 40,000 personnel, the coalition’s Regional Command (Southwest) combined base on Sunday resembled a dust-swept, well-fortified ghost town. Also Read – Health remains key challenge in India’s development: KovindConcrete blast walls and razor wire were left guarding empty sand lots and barracks. Offices were bare, and bulletin boards stripped of photo tributes of fallen American troops.  The most recent official estimate of combined international troops at the base was 4,500 – and those last few will be gone soon, officials said. After the withdrawal, the Afghan National Army’s 215th Corps will be headquartered at the 6,500-acre base, leaving almost no foreign military presence in Helmand.last_img read more