Breaking down superfluidity

first_img Citation: Breaking down superfluidity (2007, September 4) retrieved 18 August 2019 from https://phys.org/news/2007-09-superfluidity.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. The results are available in Physical Review Letters, in a piece titled “Critical Velocity for Superfluid Flow across the BEC-BCS Crossover.”In ultracold gases, the BEC-BCS crossover basically addresses how superfluidity in bosons transforms into superfluidity in fermions. At issue, says Ketterle, is how fermions can be made to interact very strongly so that superfluidity occurs at higher temperatures. Furthermore, an improved understanding of the pairing mechanism can lead to the developments of new materials that could serve as superconductors. “Bare electrons repel each other,” says Ketterle, “unless there are many other particles around them which can lead to some attraction and to pairing. Once paired, fermions act as bosons.” So far, the group has studied fermionic atoms with attractive interactions, but in the future, they hope to see how to pair fermions, which repel each other, to resemble the electrons.“These are important issues,” Ketterle explains. “Superfluids and superconductors have many possible applications. We use them now, but if we understood them even better, more applications could open up.” He illustrates: “Imagine having a superconducting power grid where energy flows without resistance or developing better magnets for MRIs.” These are only a couple of the applications that scientists can think of now. “A better understanding of superfluids may lead to the design of new materials in the future.”But for the here and now, Ketterle’s team has managed to create conditions that use tuning to control the pairing of fermions. “When we modify the external magnetic field, we can loosen up the binding between the particles until they reach a point where two of them are not bound at all, but many of them still are.”The MIT team studied the critical velocity only in the center of the atom cloud, avoiding the limitations of inhomogeneous density. They moved an optical lattice (an interference pattern between two laser beams) through the superfluid. The group found that the critical velocity is highest when molecular pairs transform into Cooper pairs “in which attractive forces are about to support a molecular state.” Ketterle expects other studies to follow — and to perform additional quantitative tests of the theoretical predictions. “We have seen that this system allows us to study the breakdown of superfluidity,” Ketterle says. “The ultimate goal is to use our new tools and methods to find new regimes of superfluidity, to find out for what interactions and in what kind of geometry superfluidity is most robust,” says Ketterle. “This is an exciting frontier. We are able to study superfluids over the whole range of interactions throughout the crossover. This is the latest advance toward understanding superfluidity and superconductivity.”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. Explore furthercenter_img MIT physicists shed new light on superfluidity “One of the most exciting areas of research in the last few years has been the realization of the BEC-BCS crossover,” Wolfgang Ketterle tells PhsyOrg.com. Ketterle and a team of scientists at the MIT-Harvard Center for Ultracold Atoms have completed the first study of critical velocities in this crossover region where magnetic tuning of the interactions is possible by a Feshbach resonance.last_img read more

Chatbot autotweets replies to climate change arguments

first_img Nigel Leck’s creation is @AI_AGW (also known as Turing Test), and the script searches the Twitter site for hundreds of phrases he believes tend to be used by those who think global warming is not occurring, or who think it is occurring but is not anthropogenic or entirely anthropogenic. When the script finds one of the phrases it then “tweets” a response from an extensive database of countering phrases.The return tweets are selected to match the phrases found so, for example, tweets about global warming occurring on Mars or Neptune will produce a response suggesting this does not prove the sun is warming and producing Earth’s global warming. Tweets often contain a link to a scientific source or a video refuting the argument.Leck said he originally wrote many of the rebuttals himself, but he has now extracted many from a university source, but one which he will not identify. Some of the responses relate to religion, which is where Leck says debates with the chatbot often end up.The tweets are not identified as autoresponses, although the name provides clues, and Leck said many people receiving them continue their “conversations” for hours or days, which is possible because the program selects from a range of responses and does not reply the same way each time.Leck said if the program “argues them into a corner,” there tends to be two “crowds”: one who resort to the “God created it that way” final response, and a second group Leck calls “skeptics so unyielding they won’t be swayed by any amount of argumentation.”One problem with the chatbot is its inability to spot sarcasm, which is often rife during extreme weather events such as heat waves, when many tweets suggest it’s so hot outside it’s “a good thing global warming is a myth,” or cold snaps, when tweets sarcastically suggest global warming is a hoax. Leck said the program includes an algorithm that enables it to learn to recognize such false positives, but that he promptly apologizes when the chatbot is found to have irritated Twitter users who are not arguing about climate change, and whitelists their accounts. Leck said he intends to expand the program at some time by enabling it to cull new phrases from tweets from others (presumably also non-scientists like Leck) debating with those skeptical of climate change arguments. He said this would allow it to argue “into the ground” the increasing number of what he called “anti-science tweeters who are unwilling or unable to look up the proper scientific literature themselves.” (PhysOrg.com) — A software developer has created a “chatbot” program for Twitter to automatically detect set phrases associated with arguments put forward by those skeptical of anthropogenic global warming, and to send automated replies of set phrases debunking their arguments. 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. Citation: Chatbot auto-tweets replies to climate change arguments (2010, November 4) retrieved 18 August 2019 from https://phys.org/news/2010-11-chatbot-auto-tweets-climate-arguments.html Using mathematics to identify the good guys  Explore further © 2010 PhysOrg.comlast_img read more

Forest and savanna can switch quickly

first_img Explore further Acacia savanna south of Fada N’Gourma, Burkina Faso. Image: Wikipedia. (PhysOrg.com) — Two recent studies have found that environmental changes can bring previously stable forests and grasslands to tipping points that produce sudden large-scale and sometimes irreversible changes in which forest can become savanna and vice versa. These findings challenge previous assumptions that changes to natural systems occur continuously and smoothly. In one study published in Science, scientists in The Netherlands, led by Marina Hirota of Wageningen University, studied NASA satellite data on forests (around 80% trees), savanna (around 20%) and treeless areas (about 5% tree cover). The group found that intermediate regions were rare, and that the rainfall was the primary factor determining which landscape would be found. The researchers also found that big shifts can suddenly occur in the type of landscape, rather than the slow, smooth transition expected.In a US/South African study also published in Science, researchers led by A. Carla Staver of Princeton University found that the degree of tree coverage generally depends on rainfall and seasonal changes, but in areas where the rainfall level is intermediate (1000-2500 mm annual) and seasonal changes are mild, fire becomes the most important factor in determining whether forest, grassland or treeless landscapes were likely to predominate. They found a tipping point at 40-45% tree coverage: below this fires spread rapidly, and above this the increased tree coverage slows down the spread of fires.Both groups studied data collected by NASA’s Aqua and Terra satellites, which use MODIS (Moderate Resolution Imaging Spectroradiometer) instruments to detect vegetation coverage and determine the type of vegetation prevailing. They both concentrated on areas thought to be least affected by human activity, including subtropical and tropical parts of Australia, South America, and Africa.Prevailing theories of ecological development suggest that if the rainfall on a savanna gradually increases, the number of trees should also gradually increase until the region becomes a forest. The new studies suggest instead that the savannas remain grasslands as the rainfall increases until a tipping point is reached, at which time the savanna suddenly switches to a fully-forested area instead. Such sudden changes have been noted on a local scale but until now it had not been known that they occurred on a global scale.The findings could have implications for people whose livelihoods depend on their landscape remaining the same, since it could change rapidly, which would require people to also adapt quickly to the changes. To assist them, Hirota’s team has developed what they call resilience maps identifying regions close to the tipping point. The two studies could also help to refine climate change models, which currently assume the transition between grassland and forest is gradual and depends mainly on rainfall and temperatures. © 2011 PhysOrg.comcenter_img Study identifies two types of savannas Citation: Forest and savanna can switch quickly (2011, October 14) retrieved 18 August 2019 from https://phys.org/news/2011-10-forest-savanna-quickly.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

AMD rolls out 6300 server chips for higher performance watt

first_img © 2012 Phys.org Citation: AMD rolls out 6300 server chips for higher performance / watt (2012, November 5) retrieved 18 August 2019 from https://phys.org/news/2012-11-amd-server-chips-higher-watt.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. (Phys.org)—Advanced Micro Devices (AMD) on Monday announced its launch of 16-core Opteron 6300 server chips. This is its newest series in server processors based on the chip designer’s Piledriver core architecture. The Opteron 6300 family has models with four, eight, 12 or 16 processor cores (up to 16 cores per socket for scaling in “thread-intensive” environments). AMD says the processors are designed for “virtualized server platforms that are central to private and public cloud deployments, big data systems and high-performance computing (HPC) clusters.” This is a sequel to its 6200 series; the 6300 series “Piledriver” chips show better speed than the 6200 series. More information: Press releasecenter_img Quad-Core AMD Opteron Processor Family Expands with New Low-Power Options The speed improvement is 40 percent—up to 40 percent higher performance per watt than the prior generation, according to AMD. That makes the new 6300 launch especially suitable for businesses running large-scale software systems, said AMD.Data centers are attracted to many-core processors for their needs, and the 6300 family should be attractive at data centers with heavy workloads. Dell thinks so. A spokesperson said, in the AMD press release, that the 6300 series can offer its customers performance gains beneficial for cloud computing, big data, and high growth data-center applications. Technical details include AMD Virtualization technology for virtualized environments, up to four memory channels with up to 1866 MHz memory, and support for ultra-low voltage 1.25v memory.Servers from Dell and HP based on the AMD Opteron 6300 Series processors will be available by the end of the year. AMD said the AMD Opteron 6300 Series processor will also be leveraged as part of a supercomputing deployment at Indiana University.The school’s earlier Big Red supercomputer is being replaced with Big Red II, for high-performance parallel computing, capable of performing one quadrillion floating-point operations per second (1 petaflop). The school provided details on the Big Red II computing environment. There will be two AMD X86-64 processors with 16 cores each, the nodes providing 32 cores and 64 GB of memory per node; plus GPU-enabled compute nodes, containing one AMD X86-64 processor and one NVIDIA GPU, with these nodes providing 32 GB of memory. All compute nodes are connected through the Cray Gemini interconnect.The 6300 launch this week follows AMD’s October “ambidextrous” announcement that it will be taking a new strategic move to bridge x86 and ARM processors for cloud and data center servers. The company said its goal in doing so is to offer desirable performance-per-watt for dense cloud computing solutions. The first 64-bit ARM-based processors for servers are expected in 2014. Explore furtherlast_img read more

Best of Last Week – First map of hidden universe pursuit of

first_img3D map of the cosmic web at a distance of 10.8 billion light years from Earth. The map was generated from imprints of hydrogen gas observed in the spectrum of 24 background galaxies, which are located behind the volume being mapped. This is the first time that large-scale structures in such a distant part of the Universe have been mapped directly. The coloring represents the density of hydrogen gas tracing the cosmic web, with brighter colors representing higher density. Credit: Casey Stark (UC Berkeley) and Khee-gan Lee (MPIA) Citation: Best of Last Week – First map of hidden universe, pursuit of compact fusion and new clues about the causes of depression (2014, October 20) retrieved 18 August 2019 from https://phys.org/news/2014-10-week-hidden-universe-pursuit-compact.html It was a pretty big week for earth and space scientists, too, as an international team of researchers announced that they’d found evidence that Earth’s magnetic field could flip within a human lifetime—or put another way, as quickly as within a hundred years. Also another team of researchers in the U.S. took another look and found that the increase of CO2 in the atmosphere is lower than predicted because of plants. And that top secret shuttle-looking plane the U.S. Air Force has been testing landed at an Air Force base in southern California after flying for nearly two years, inviting widespread speculation as to its purpose.In more practical news, scientists in Singapore have come up with a new type of battery that can be recharged up to 70 percent in just two minutes—and will last up to 20 years. And a team at Siemens announced that they’d developed a drive system that saves space and weight in electric cars—allowing the cars to go farther on a charge. Unrelated but still remarkable, a team of researchers in the U.K. announced that they had found what they believe to be the underlying cause of 40 per cent of pre-term births—if they can find a cure, it might mean drastically reducing the number of deaths of babies due to premature birth.And finally, it turns out that depression in some people may be related to the way gut bacteria helps keep the brain healthy–and how it could play a role in the treatment of depression. Have we been causing our own depression by killing off our gut biome with antibiotics? New research suggests that’s entirely possible. © 2014 Phys.org (Phys.org) —It was an interesting week for physics as scientists built the first map of the hidden universe—astronomers led by a team with the Max Planck Institute in Germany created the first 3D map of the universe depicting things just three billion years after the Big Bang. Also, Lockheed Martin revealed new details about its pursuit of a compact fusion reactor concept, announcing they are on the fast track to developing what they describe as the ultimate power source and predicting they’ll have a prototype in just five years. And a team of physicists from China and Singapore conducted quantum tests that strengthen support for EPR steering—it concerns particularly strong types of entanglement in which the two systems are not just correlated, but are correlated in a specific direction.center_img Explore further Top-secret space plane lands on California coast 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 birds and insects reacted to the solar eclipse

first_img A break from the buzz—bees go silent during total solar eclipse In this new effort, the researchers sought to better understand how creatures such as birds and insects respond to atypical periods of darkness such as a total solar eclipse. To that end, they gained access to data from 143 weather stations that had captured the activities of multiple birds and insects in different parts of the United States during the August 21, 2017, solar eclipse. They note that due to the short lifespan of birds and insects, none of them would ever have experienced an eclipse before. Thus, the sudden darkness would present an unexpected change in their environment.In looking at the Doppler radar data and analyzing it using machine-learning programs, the researchers were able to establish movements of flying species from near the ground to approximately three miles up in the air. They report seeing unusual activity up to 50 minutes before the eclipse reached totality—many of the flying creatures began returning to ground or other perches. This was particularly so for those flying at high altitudes. The researchers suggest that it seems reasonable to attribute the change in activity to the creatures responding as they would to a storm—seeking shelter is a natural response to weather conditions that can prove deadly for small flying creatures.The researchers also found something they thought was strange: A group of flyers, likely birds, changed their behavior just before totality, suddenly taking flight and quickly settling back to their perches once again. They suggest the reason was because the birds had become confused, at one moment thinking that normal darkness had arrived, only to discover that it was something else.The researchers are planning to collect even more data the next time around—in 2024, a total solar eclipse will once again pass over major parts of the continental United States. They hope more precise radar data might be able to differentiate between animals. 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 (a) The path of eclipse totality through the network of weather surveillance radars in the continental USA, 21 August 2017. All 143 sites included in this study, coloured by the maximum amount of obscuration. The path of totality, where obscuration is 100%, is shown in grey, and the eight sites located within the path of totality are outlined in black. (b–g) Patterns of biological activity in the atmosphere as sampled by NEXRAD. The smoothed mean (generalized additive model) amount of vertically integrated reflectivity (VIR) at all sites, grouped after amount of maximal obscuration: (b) during the eclipse (less than 80: n = 54, 80–95: n = 58, 95–100: n = 26), (c) at sunset the day of the eclipse (less than 80: n = 52, 80–95: n = 59, 95–100: n = 26); and at the time of day of the eclipse on: (d) 19 August (less than 80: n = 54, 80–95: n = 58, 95–100: n = 27), (e) 20 August (less than 80: n = 54, 80–95: n = 59, 95–100: n = 27), (f) 22 August (less than 80: n = 55, 80–95: n = 59, 95–100: n = 27), and (g) 23 August (less than 80: n = 55, 80–95: n = 60, 95–100: n = 27). Note different scale on y-axis in (c). Credit: Biology Letters (2018). DOI: 10.1098/rsbl.2018.0485 Citation: How birds and insects reacted to the solar eclipse (2018, November 14) retrieved 18 August 2019 from https://phys.org/news/2018-11-birds-insects-reacted-solar-eclipse.htmlcenter_img A team of researchers with Cornell University and the University of Oxford has found that birds and insects reacted in some surprising ways to the 2017 U.S. total solar eclipse. In their paper published in the journal Biology Letters, the group describes their study of birds and insects during the solar eclipse using Doppler radar data and what they found. © 2018 Science X Network More information: Cecilia Nilsson et al. Aeroecology of a solar eclipse, Biology Letters (2018). DOI: 10.1098/rsbl.2018.0485 Journal information: Biology Letterslast_img read more

MacArthur Genius Recipient Jennifer Eberhardt Discusses Her New Book Biased

first_imgJennifer Eberhardt is a scientist, a social psychologist who studies how we interact with one another. For more than two decades, she has been unpacking implicit racial bias, how our perceptions of race play into our everyday interactions, even when we’re not aware of it. She’s trained police departments and guided tech startups on recognizing their own implicit bias and how it affects their work. Now she’s written about her research in a new book called “Biased: Uncovering The Hidden Prejudice That Shapes What We See, Think, And Do.” Read the whole story: NPR MacArthur Genius recipient Jennifer Eberhardt has a new book, Biased: Uncovering the Hidden Prejudice That Shapes What We See, Think and Do.last_img read more

When will we girls feel safe

first_imgAs I heard the horror story about the girl who was gang raped, I felt a stir in my soul. I felt angry and frustrated for all those girls who aspire to improve their lot in life without hiding behind a man. It is truly a heart-wrenching story that has sparked a revolution.From my experiences from across the globe, I have noticed that India is predominantly an orthodox society. Dress code for women is still a issue in India. The show of legs or cleavage by girls is considered provocative and even the advent of Facebook and the android phone has done little towards improving the image of women. Wearing shorts or tight tops is still frowned upon. It is a common sight to see a group of guys leering at a shapely girl wearing a pair of shorts and a tee. Also Read – ‘Playing Jojo was emotionally exhausting’So why does this kind of behaviour happen?One of the reasons may be increased Westernisation which has helped this country to catch up with the rest of the world in many ways in less than 20 years. The mindset some sections of males might have not adjusted to this rapid evolution.In recent times, however, public places too have evolved. With the advent of the malls, things have become a bit better as they  act as ‘safe zones’ for modern women. Girls feel free to wear tight clothes and shop their favourite high street brand without the fear of being teased. However, once you exit, the streets outside are completely different story. With regard to the words ‘safe zone’, what got me introspecting was an explanation given to me by a friend who relocated to New Delhi from New York. Also Read – Leslie doing new comedy special with NetflixIn her words ‘it is ok for a women to wear anything in Delhi provided she travels in her own car and goes to the right places’.  This sounded discriminatory. What about all the lakhs of women in Delhi who live alone and need to travel by public transport? Will they never enjoy the freedom my expat friend experiences? These pressing questions need to be answered soon. However, I choose not to be steeped in such pessimism. One thing that has become clear is the accommodating nature of the Indians. From a time when an onscreen kiss was considered taboo, India has come a long way. The entertainment industry today has become a frontrunner in upholding woman’s rights, at least to some extent. With the advent of reality television the general public has become more accepting towards the image of a more Westernised Indian woman. We have welcomed talent from across globe in film and TV. Even an international adult movie star has been accepted as mainstream heroine. This of course cannot be considered a landmark change, but it indicates the change in the mindset of the modern Indian male.But to what extent the image of the bold Indian woman on celluloid proves helpful to the common Indian girl is open to debate…..Salloli Kumar is a regular on the page 3 circuit for nearly a decade…last_img read more

Italy on opera singers mind

first_imgHe wanted to be a magician as a child, for connecting with people is what he enjoyed most. However, what got this boy noticed was not the tricks up his sleeve, but his voice. Toshannbor Singh Nongbet, perhaps one of India’s only Italian opera singers, didn’t look back ever since he started singing and he has come a long way.‘I heard a lot of Pavarotti and Placido Domingo,’ says 22-year-old Nongbet who was in the Capital recently to perform at Indian Council of Cultural Relations (ICCR). Accompanying him in an evening of jazz and opera were other artistes like pianist Ronojit Chaliha, guitarist Amarnath Hazarika and drummer Samuel Shullai. Also Read – ‘Playing Jojo was emotionally exhausting’Popularly known as Toshan, Nongbet graduated in BA Music Honours in 2012 from St Anthony’s College, Shillong. He has been a member of the Aroha Choir from 2011. He filled in as a bass but he is truly a tenor and has featured as a soloist in many occasions. In 2012 end, Toshan reached the final round of the reality show India’s Got Talent Season 4 and was declared the fourth runner up.Stage fright is what kept Nongbet from acing the magic act perhaps, he ponders speaking to Also Read – Leslie doing new comedy special with NetflixMillennium Post. ‘But singing made me overcome it all,’ says he adding that once he started singing he bonded better with people.Though his formal training started only when he was 19, Nongbet has made his mark in the music circuit. When he was younger, he dabbled in all genres but over time opera captured his imagination and the journey has begun.Italy is next in Nongbet’s line of sight, he wants to go there to train properly since opera is not a well known concept in India and the lucky guy has his whole family supporting him. While he makes it very clear that Bollywood is not on the cards at all, he just wishes the country could have offered more for his art.‘ICCR’s support to Aroha Choir led by Toshanbor is an attempt to diversify this support to the large number of artistes from Northeast and Meghalaya,’  said Dr. Suresh K Goel, Director General, ICCR.last_img read more

Bizman shot dead at pointblank range in broad daylight at Uluberia

first_imgKolkata: A businessman was shot dead at point-blank range in Uluberia on Sunday afternoon.Though the police are yet to ascertain the exact reason behind the murder, they suspect that monetary gain was the main motive behind the crime as the victim was returning home with a huge amount of money.Police said the victim, Subhojit Garai (38), was a distributor of different biscuit companies. He was a resident of Hanskhali in Uluberia itself.After the preliminary investigation, police have come to know that the victim used to go for cash collection on every Sunday from the shops where he used to supply biscuits. His family members told the police that he left home in the morning and the incident took place when he was returning home. Also Read – Heavy rain hits traffic, flightsHe was on his motorbike. Suddenly, three persons on another motorbike started following him. The miscreants had their faces covered and they forced the victim to stop his two-wheeler.He was pushed when he stopped the motorbike and eventually fell on the road. They were trying to take away his handbag containing a huge amount of money but the businessman was not ready to let go of the bag. The miscreants opened fire at the businessman, who received bullet injuries on his stomach. The miscreants took the bag containing the money while the victim was left writhing in pain. They fled the spot on the motorbike. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedLocals rushed to the spot after hearing the sound of firing and found the businessman lying in a pool of blood on Uluberia-Shyampukur Road. They immediately informed the police. Policemen from the local police station reached the spot and sent the body for an autopsy.According to police, the miscreants had been keeping a watch on the victim for the past few weeks and they were well aware of the route he used to take to reach home after collection on every Sunday.Police are yet to arrest anyone in this connection. The investigating officer spoke to some of the locals to find out someone who has witnessed the incident. They also spoke to the victim’s family members to know if he had received any threat call in the past few days or if anyone had threatened him with dire consequences. Police have also asked his family members if they suspect anyone who might be behind the crime.last_img read more