Information sharing interferes with wisdom of crowds study

first_img Is that your final answer? Study suggests method for improving individual decisions More information: How social influence can undermine the wisdom of crowd effect, PNAS, Published online before print May 16, 2011, doi: 10.1073/pnas.1008636108AbstractSocial groups can be remarkably smart and knowledgeable when their averaged judgements are compared with the judgements of individuals. Already Galton [Galton F (1907) Nature 75:7] found evidence that the median estimate of a group can be more accurate than estimates of experts. This wisdom of crowd effect was recently supported by examples from stock markets, political elections, and quiz shows [Surowiecki J (2004) The Wisdom of Crowds]. In contrast, we demonstrate by experimental evidence (N = 144) that even mild social influence can undermine the wisdom of crowd effect in simple estimation tasks. In the experiment, subjects could reconsider their response to factual questions after having received average or full information of the responses of other subjects. We compare subjects’ convergence of estimates and improvements in accuracy over five consecutive estimation periods with a control condition, in which no information about others’ responses was provided. Although groups are initially “wise,” knowledge about estimates of others narrows the diversity of opinions to such an extent that it undermines the wisdom of crowd effect in three different ways. The “social influence effect” diminishes the diversity of the crowd without improvements of its collective error. The “range reduction effect” moves the position of the truth to peripheral regions of the range of estimates so that the crowd becomes less reliable in providing expertise for external observers. The “confidence effect” boosts individuals’ confidence after convergence of their estimates despite lack of improved accuracy. Examples of the revealed mechanism range from misled elites to the recent global financial crisis. Social influence effect: Social influence diminishes group diversity without diminishing the collective error. Typical examples of experimental sessions for three information conditions, displaying five individual responses. Image (c) PNAS, doi: 10.1073/pnas.1008636108 Citation: Information sharing interferes with ‘wisdom of crowds’: study (2011, May 17) retrieved 18 August 2019 from https://phys.org/news/2011-05-wisdom-crowds.html (PhysOrg.com) — A statistical phenomenon, called the Wisdom of Crowds, happens when a group of individuals make guesses and the average of the guesses reveal accurate average answers. However, researchers have discovered that when the individuals are made aware of other participant’s guesses, there is a clear disruption to the accuracy of the guesses. © 2010 PhysOrg.com The study, led by mathematician Jan Lorenz and sociologist Heiko Rahut from Switzerland’s ETH Zurich published their recent findings in Proceedings of the National Academy of Sciences, showing that even a small amount of social influence on a group can interfere with the Wisdom of Crowd effect.For the study, researchers brought in 144 students and placed them in isolated locations and asked them to guess things like how many crimes were committed in 2006 and what the population density of Switzerland was. Based on the accuracy of their answers, participants were given a small monetary award and then the process was repeated for a total of four rounds. The students were broken up into two groups, with one group receiving information on what other peers had guessed and the other remaining isolated.As each round continued, the group with no influence by other peers showed their results becoming more accurate. The individuals that received information on what their peers were guessing however showed less accuracy in their answers.Researchers found that those receiving social input from their peers either led individuals to second guess themselves or, seeing others may have answered the same, become more confident in their incorrect responses. According to the results of the study, the Wisdom of Groups phenomenon appears to only be accurate when the individuals in the group are not aware or influenced by others in the group. 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 furtherlast_img read more

Germany sets weekend record for solar power

first_img Citation: Germany sets weekend record for solar power (2012, May 30) retrieved 18 August 2019 from https://phys.org/news/2012-05-germany-weekend-solar-power.html Explore further Image: Array Technologies That comparison is significant because, in the wake of the Fukushima nuclear disaster in Japan, Germany abandoned nuclear energy endeavors. They shut down eight plants in favor of safer options and instead shouldered the task of further developing renewable energy sources. Allnoch said the data is based on information from the European Energy Exchange (EEX), based in Leipzig.Germany aggressively supports alternative energy sources and, by the year 2022, Germany expects to shutter its remaining nine nuclear power plants. The lack of these nuclear power facilities will create a gap in the country’s energy infrastructure, however. Germany is looking toward sources such as solar, wind and biomass.That support and commitment have come at a price. A 2012 Environment Ministry report showed that German taxpayers pay an extra four billion euros per year on top of their electricity bills to support solar power.Allnoch and his supporters would prefer to look at the “price” context in another way. “Even with all the safety precautions”, he said, there is still a risk at nuclear plants. “A global phaseout would be ideal but is not likely to happen soon.”As for costs, he said that while everyone worries about costs, the markets are shifting. He said once the uncertainty calms down, “we will see that we can do without nuclear power.”In relegating nuclear energy to the past, the road to replace it may be rocky, he added, but it is do-able. “We need to rise to this challenge.”The new record-breaking figures from Germany, however, do not quiet some energy experts who stress that without good storage strategies for excess power, such record-breaking numbers are not meaningful. They say the real point is to get consistently large percentages of power from renewable sources. German cabinet passes nuclear exit billlast_img read more

Study indicates Spanish conquest of Peru may have resulted in changes to

first_img The sand dune ridges along the northern coast of Peru came about, the researchers claim, due to earthquakes loosening sand deposits in the Chira valley. That sand was eventually swept into rivers which carried it to the sea. Currents then carried it north eventually depositing it along the shoreline, building up over time into large ridges. Radiocarbon dating of charcoal remnants from fire pits atop some of the ridges has shown them to have formed from over 5000 years ago to as recently as 400 years ago. Excavating one of the existing ridges, the two researchers report, revealed mollusk shells which because there were so many of them, served as a shield against the wind, which would have blown the sand off the ridges long ago, had not the shells been there to offer protection.The Inca, the researchers report, lived along the shorelines of northwest South America for thousands of years, catching, cooking and eating mollusks and tossing the shells aside as they sat atop a ridge. The result was millions of shells littering the surface of the ridges, forming armor of sorts, which allowed the ridges to remain intact far longer than they would have otherwise. But, then, the Spanish arrived, conquering the Incas and forcing them to move inland. After that, the shell littering ceased—without a constantly rejuvenated suit of armor, many of the ridges succumbed to the winds and vanished. Thus, the coast was altered in a way that neither the Inca nor their conquerors could have possibly imagined. Space image: Aorounga Crater, Chad (Phys.org) —A study by a pair of researchers with the University of Maine suggests that the northern coast of Peru may have been altered due to population shifts as a result of the Spanish conquest in the 1500’s. In their paper published in Proceedings of the National Academy of Sciences, Daniel Belknap and Daniel Sandweiss describe a field study they conducted in the area that suggested that Inca living on the coast prior to the Spanish conquest, may have inadvertently been supporting the existence of sand ridges by discarding mollusk shells. After they left, it appears, some of the sand ridges were blown away by the wind. Citation: Study indicates Spanish conquest of Peru may have resulted in changes to coastal shoreline (2014, May 20) retrieved 18 August 2019 from https://phys.org/news/2014-05-spanish-conquest-peru-resulted-coastal.html Journal information: Proceedings of the National Academy of Sciences Surface of ridge J and test pit surface test pit-Chira-1997-number 4: STP-C-97-4. Credit: PNAS, doi: 10.1073/pnas.1404568111center_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. Explore further © 2014 Phys.org More information: Effect of the Spanish Conquest on coastal change in Northwestern Peru, Daniel F. Belknap, PNAS, DOI: 10.1073/pnas.1404568111AbstractWhen Francisco Pizarro and his small band of Spanish conquistadores landed in northern Peru in A.D. 1532 to begin their conquest of the vast Inca Empire, they initiated profound changes in the culture, language, technology, economics, and demography of western South America. They also altered anthropogenically modulated processes of shoreline change that had functioned for millennia. Beginning with the extirpation of local cultures as a result of the Spanish Conquest, and continuing through today, the intersection of demography, economy, and El Niño-driven beach-ridge formation on the Chira beach-ridge plain of Northwestern Peru has changed the nature of coastal evolution in this region. A similar event may have occurred at about 2800 calibrated y B.P. in association with increased El Niño frequency.last_img read more

Bridgmanite sample found to remain stable at lower mantle conditions

first_imgSchematic picture of the Earth’s interior. On the right side is the example of the part of the two-dimensional wide scan of x-ray diffraction image of Fe, Al-bearing bridgmanite, on the left side is the crystal structure of pure Fe-bridgmanite. Credit: Leyla Ismailova/University of Bayreuth More information: L. Ismailova et al. Stability of Fe,Al-bearing bridgmanite in the lower mantle and synthesis of pure Fe-bridgmanite, Science Advances (2016). DOI: 10.1126/sciadv.1600427AbstractThe physical and chemical properties of Earth’s mantle, as well as its dynamics and evolution, heavily depend on the phase composition of the region. On the basis of experiments in laser-heated diamond anvil cells, we demonstrate that Fe,Al-bearing bridgmanite (magnesium silicate perovskite) is stable to pressures over 120 GPa and temperatures above 3000 K. Ferric iron stabilizes Fe-rich bridgmanite such that we were able to synthesize pure iron bridgmanite at pressures between ~45 and 110 GPa. The compressibility of ferric iron–bearing bridgmanite is significantly different from any known bridgmanite, which has direct implications for the interpretation of seismic tomography data. Journal information: Science Advances (Phys.org)—A diverse team of researchers with members from Germany, France, Russia and the U.S. has subjected a sample of bridgmanite to conditions believed to be present at Earth’s lower mantle and has found that it remained stable. In their paper published in the journal Science Advances, the team describes the testing they conducted, what they found and their theory regarding the dynamo effect that is, perhaps, the source of the planet’s magnetic field Citation: Bridgmanite sample found to remain stable at lower mantle conditions (2016, July 18) retrieved 18 August 2019 from https://phys.org/news/2016-07-bridgmanite-sample-stable-mantle-conditions.html Developing a picture of the Earth’s mantlecenter_img Explore further Studying the interior of planet Earth is difficult due to the huge scale involved—researchers cannot simply drill a hole all the way to the core to grab samples of material. For that reason, they have developed and used other tools such as seismic monitors to learn more. Though the have learned much, there is still a lot that is unknown or uncertain. One of these uncertainties is the makeup of the planet’s lower mantle—the part just next to the core. Prior research has indicated that it is likely a mineral called bridgmanite. Other researchers have suggested that bridgmanite would not be stable under the very high temperature and pressure that would exist in the lower mantle. In this new effort, the researchers sought to settle this debate by bringing samples of bridgmanite into their lab and testing it.To exert very high pressure on the sample similar to that believed to exist in the lower mantle, the researchers used laser-heated diamond anvil cells—creating a vice-like grip by squeezing a very small sample between two diamonds and focusing a laser on them. The team ran several such experiments at different temperatures and pressures, maxing out at 23 gigapascals and 1,800 Kelvin. They then used X-rays to examine the samples to see how they held. The team reports that the samples held up very well and concluded that bridgmanite is stable under the conditions believed to exist at the lower mantle.The team found that when samples contained different amounts of iron, there were differing levels of stability. Those differences, they suggest, could offer an explanation for seismic activity deep in the planet which could play a role in establishing the dynamo that is responsible for the planet’s magnetic field. © 2016 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

Physicists extend stochastic thermodynamics deeper into quantum territory

first_img The physicists, Anthony Bartolotta, a graduate student at Caltech, and Sebastian Deffner, Physics Professor at the University of Maryland Baltimore County, have written a paper on the Jarzynski equality for quantum field theories that will be published in an upcoming issue of Physical Review X.The work address one of the biggest challenges in fundamental physics, which is to determine how the laws of classical thermodynamics can be extended to the quantum scale. Understanding work and heat flow at the level of subatomic particles would benefit a wide range of areas, from designing nanoscale materials to understanding the evolution of the early universe.As Bartolotta and Deffner explain in their paper, in contrast to the large leaps made in the “microscopic theories” of classical and quantum mechanics during the past century, the development of thermodynamics has been rather stagnant over that time. Although thermodynamics was originally developed to describe the relation between energy and work, the theory traditionally applies only to systems that change infinitely slowly. In 1997, physicist Christopher Jarzynski at the University of Maryland College Park introduced a way to extend thermodynamics to systems in which heat and energy transfer processes occur at any rate. The fluctuation theorems, the most prominent of which is now called the Jarzynski equality, have made it possible to understand the thermodynamics of a wider range of smaller, yet still classical, systems.”Thermodynamics is a phenomenological theory to describe the average behavior of heat and work,” Deffner told Phys.org. “Originally designed to improve big, stinky heat engines, it was not capable of describing small systems and systems that operate far from equilibrium. The Jarzynski equality dramatically broadened the scope of thermodynamics and laid the groundwork for stochastic thermodynamics, which is a new and very active branch of research.” Thermodynamic laws that describe heat and energy are being extended to the quantum scale. Source: Pexels. Photograph by Paweł Kadysz Stochastic thermodynamics deals with classical thermodynamic concepts such as work, heat, and entropy, but on the level of fluctuating trajectories of atoms and molecules. This more detailed picture is particularly important for understanding thermodynamics in small-scale systems, which is also the realm of various emerging applications.It wasn’t for another decade, however, until the Jarzynski equality and other fluctuation theorems were extended to the quantum scale, at least up to a point. In 2007, researchers determined how quantum effects modify the usual interpretation of work. However, many questions still remain and overall, the area of quantum stochastic thermodynamics is still incomplete. Against this backdrop, the results of the new study represent a significant advance.”Now, in 2018 we have taken the next big step forward,” Deffner said. “We have generalized stochastic thermodynamics to quantum field theories (QFT). In a certain sense we have extended stochastic thermodynamics to its ultimate range of validity, since QFT is designed to be the most fundamental theory in physics.”One of the keys to the achievement was to develop a completely novel graph theoretic approach, which allowed the researchers to classify and combine the Feynman diagrams used to describe particle behavior in a new way. More specifically, the approach makes it possible to precisely calculate infinite sums of all the possible permutations (or arrangements) of disconnected subdiagrams describing the particle trajectories.”The quantity we were interested in, the work, is different than the quantities usually calculated by particle theorists and thus required a different approach,” Bartolotta said.The physicists expect that the results will allow other scientists to apply the fluctuation theorems to a wide variety of problems at the forefront of physics, such as in particle physics, cosmology, and condensed matter physics. This includes studying things like quantum engines, the thermodynamic properties of graphene, and the quark gluon plasma produced in heavy ion colliders—some of the most extreme conditions found in nature.In the future, the physicists plan to generalize their approach to a wider variety of quantum field theories, which will open up even further possibilities. What is quantum in quantum thermodynamics? More information: Anthony Bartolotta and Sebastian Deffner. “Jarzynski Equality for Driven Quantum Field Theories.” Physical Review X. DOI: 10.1103/PhysRevX.8.011033. Also at arXiv:1710.00829 [cond-mat.stat-mech] Citation: Physicists extend stochastic thermodynamics deeper into quantum territory (2018, February 13) retrieved 18 August 2019 from https://phys.org/news/2018-02-physicists-stochastic-thermodynamics-deeper-quantum.html © 2018 Phys.org Journal information: Physical Review X 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. Physicists have extended one of the most prominent fluctuation theorems of classical stochastic thermodynamics, the Jarzynski equality, to quantum field theory. As quantum field theory is considered to be the most fundamental theory in physics, the results allow the knowledge of stochastic thermodynamics to be applied, for the first time, across the full range of energy and length scales. Explore furtherlast_img read more

Marvels of cinema on stage

first_imgRaising the issue of gender equality in cinema, Arth made an extraordinary impact back in 1980s. This semi-autobiographical film directed by Mahesh Bhatt in 1982 changed the face of Indian cinema forever and is back with a bang as a theatrical production. After the recent success of   his plays The Last Salute and Trial of Errors which also launched his latest protégé Imran Zahid, the duo are now pairing up again for the dramatic adaptation of Arth Also Read – ‘Playing Jojo was emotionally exhausting’.Bhatt feels that Arth was a classic film that raised the issue of gender equality way back in the 80’s. ‘The film looked at the issue of women emancipation like no Indian dramatic work ever has. No one has been able to better what Arth highlighted in the world of movies or in theatre. I think the 21st century India needs to be experience the theme of Arth through theatre’ says the filmmaker ahead of translating the screenplay for the stage. Arth was way ahead of its time and Bhatt feels that subject will strike a chord even with today’s generation. It looked at the bold subject of extra marital relationships was also remembered for its memorable soundtrack. Also Read – Leslie doing new comedy special with NetflixBelieving that the fabric of society has not gone under a complete change over the yearsm the director adds, ‘The issues with regards to our society that were raised in Arth are relevant in even in todays times. Theater has given me an entirely new outlet and after staging two successful plays The Last Salute and Trial of Errors I took this decision.I think adapting such a piece of art into a theatrical adaptation will not be an easy task but I am ready for this test.  I feel this medium has help connecting with audience in all together different way,’ he adds.Delhi-based actor Imran Zahid , who earlier essayed the role of Muntadar Al Zaidiin The Last Salute and of journalist Rehan in Trial of Errors is all gearing up for this new assignment.‘Mahesh Bhatt is all set to recreate magic of film in a theatrical play. It’ll be a big challenge for me to play the lead but I am up for it,’ says Imran.last_img read more