Maxwells demons may drive some biological systems

first_imgConventionally, the switching mechanism was thought to operate in equilibrium, where the switch changes between clockwise and counterclockwise motor rotations in a balanced way. An earlier experiment showed that the time interval a flagllear motor spends in a given state (either clockwise or counterclockwise) follows a peaked distribution. Based on Tu’s work, this peaked interval time distribution indicates that the switch operates out of equilibrium. In order to achieve this fast and accurate switching, the switch must be extremely sensitive to the CheY-P concentration. In the non-equilibrium model, Tu shows that this high sensitivity can be explained by the presence of two Maxwell’s demons, which act as the switch’s sensors for the CheY-P. “The easiest way to explain the work of these two Maxwell’s demons is that they are two coincidence counters,” he said. “Each switch can have up to 34 CheY-P regulators bind to it. One of the demons will count the number of bound CheY-P, and if the number is greater than some threshold, say 22, it will switch the motor from CCW to CW; another demon works the opposite way with a low threshold, say 12. If the number of CheY-P bound is less than 12, this demon will switch the motor from CW to CCW.”These “demons” consume energy to do their work, in accordance with the second law of thermodynamics. The more energy the demons use, the more sensitive the switch is. Tu determined the exact amount of energy used per switch cycle, and discovered that it is roughly equal to the work done by one or two protons moving through the membrane near the flagellar motor. Based on this finding, he predicts that the switch may be powered by protons passing through the membrane. This possibility would agree with earlier observations that the average switching frequency depends on the proton flux.As Tu explains, viewing the flagellar motor switch in the framework of a non-equilibrium model could help scientists understand the switching mechanism as an integrated part of the motor system. In biology, many systems operate out of equilibrium, and Tu’s model could help scientists detect interesting non-equilibrium effects. Besides the flagellar motor, he predicts that a similar non-equilibrium mechanism, driven by Maxwell’s demons, could be responsible for a variety of other cellular processes.More information: Tu, Yuhai. “The nonequilibrium mechanism for ultrasensitivity in a biological switch: Sensing by Maxwell’s demons.” PNAS, August 19, 2008, vol. 105, no. 33, 11737-11741.Copyright 2008 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. (PhysOrg.com) — According to the second law of thermodynamics, entropy always increases. For example, two bodies of different temperatures, when brought into contact, will eventually mix together to result in a uniform temperature. 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. But, as the physicist James Clerk Maxwell famously suggested in 1871, what would happen if a theoretical demon could stand at a doorway between the two bodies, and only allow high-temperature particles to pass through one way, and only low-temperature particles to pass through the other? The tiny doorman would prevent the two temperatures from mixing, and theoretically prevent entropy. Of course, the demon would use energy to do this job, thus creating entropy itself, and so the second law would not be violated.While Maxwell’s demon was originally considered a thought experiment, similar mechanisms have been discovered for various applications. One example is a Ranque-Hilsch vortex tube, which is a pneumatic device that separates hot and cold air by spinning hot and cold molecules in different directions.Now, a recent study shows that a similar mechanism may drive a motor switch in the bacteria Escherichia coli, and may be responsible for many other signaling systems in biology. Researcher Yuhai Tu at IBM’s T.J. Watson Research Center in Yorktown Heights, New York, explains how E. coli’s Maxwell’s demons work in a recent issue of the Proceedings of the National Academy of Sciences.“There are two related contributions made in this paper,” Tu told PhysOrg.com. “First, a general non-equilibrium mechanism for making a highly sensitive switch (i.e., how Maxwell’s demons can be used to increase sensitivity). Second, a general result on dwell-time statistics (how long a system should stay in a given state before it switches to other states). This result can be used as a diagnostic tool to detect the existence of these demons (or non-equilibrium effects) in an unknown system.”The bacterium contains flagellar motors that drive its motion. A flagellar motor has a switch (a shift gear) whose job is to sense the concentration of a regulator called CheY-P, and then control the rotational direction of the motor to be either clockwise (CW) or counterclockwise (CCW), accordingly. “The purpose of the CW and CCW switch is to control the motion of the cell,” Tu said. “The CheY-P level is the signal (red/yellow/green light) which affects the switch (stop/slow/move). In a very loose sense, CCW results in movement and CW results in switching direction. The bacterium cell needs to control these two types of motions to navigate towards (away from) favorable (toxic) environments.” Video games are a ‘great equalizer’ for people with disabilities Citation: Maxwell’s demons may drive some biological systems (2008, September 10) retrieved 18 August 2019 from https://phys.org/news/2008-09-maxwell-demons-biological.html Explore furtherlast_img read more

Dutch study suggests WiFi possibly harmful to trees

first_img More information: Wageningen University original (Dutch): www.wageningenuniversity.nl/NL … euws/Bomen101120.htm (PhysOrg.com) — A new study carried out in the Netherlands suggests radiation from Wi-Fi networks may be damaging trees and affecting the growth of other plants near routers. Image: Wikipedia. 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: Dutch study suggests Wi-Fi possibly harmful to trees (2010, November 24) retrieved 18 August 2019 from https://phys.org/news/2010-11-dutch-wi-fi-possibly-trees.html © 2010 PhysOrg.com Shade trees fight global warming in Calif. Explore further Scientists from Wageningen University were asked to carry out the study five years ago after local officials in Alphen aan den Rijn noted that ash trees planted near a wireless router were suffering from bleeding bark, cracks, lumps, discolorations, and their leaves were dying. No bacterial or viral infection could be identified in the trees.The researchers, led by Dr. A.A.M. van Lammeren, exposed small ash trees and other plants to six sources of radiation at frequencies varying from 2412 to 2472 MHz and a capacity of 100 mW EIRP, the range common for Wi-Fi. The plants were placed at distances varying from 50 to 300 cm for a period of more than three months. The results revealed that in trees closest to the Wi-Fi source the upper and lower epidermis (skin) of the leaves developed a metallic luster and began to die off. A survey of trees in urban areas in the Netherlands showed 70 percent of all deciduous trees had similar symptoms, compared to only 10 percent five years ago, while in wooded areas away from urban centers trees were unaffected.Reports on the study may inflame concerns in some over locating wireless routers in schools and fears radiation from them may affect humans as well as trees, but the scientists concerned stress the findings are preliminary and no far-reaching conclusions can be made. The researchers say larger scale research is needed over a longer period to confirm the findings. It is unclear whether the experiments ruled out other possible factors such as the presence of more pollution in urban areas than forests. The study also acknowledges that other research carried out elsewhere has shown Wi-Fi radiation has no detrimental effects.The study will be the subject of a conference in the Netherlands in February next year.last_img read more

Antarctic moss found able to survive due to ancient penguin colony guano

first_img Discovery of rare moss boosts research via BBC Nature The find of course aroused curiosity in the researchers so they looked closer at the nitrogen and found that it was nitrogen-15, an isotope that is commonly found in seabird excrement. This led them to look a little closer at the immediate environment which led to the discovery that the moss was actually growing on what used to be the site of a large penguin colony. The researchers found not just skeletons but the tiny pebbles that penguins use for building nests. As it turns out the area had been the site of a large colony of Adelie penguins that had vacated the premises some three to eight thousand years ago, leaving behind a small mountain of guano.But how could moss today be living on bird dung left thousands of years ago? Turns out that because the environment in which the moss are living gets so cold and so dry, the guano stays nearly frozen all the time and the plants are actually freeze dried each winter, a state that would of course kill most plants. But not the varieties found in Antarctica. Instead the cycle forms the basis of a relationship that allows the plants to thrive thousands of years after the penguins left the site; and because the moss is able to live there, so too are other organisms such as insects and other small creatures. The moss will likely be able to endure for quite awhile as penguins tend to produce a lot of excrement as recent reports have indicated that modern penguin colonies create so much that it can be seen from space.What’s also interesting is how the moss is able to survive being freeze dried every year. Further study will hopefully shed some light on which chemicals it produces to achieve such a feat, which could in turn help researchers in other sciences discover new ways to store food or medicine. © 2012 Phys.Org (Phys.org) — Researchers studying moss in an elevated site in East Antarctica recently began wondering how it is that the fuzzy green plants are able to not just survive in the barren landscape, but to thrive. In that part of the continent, there isn’t much soil, just sand and rock; yet the moss, like virtually all other plants needs nutrients to survive, specifically nitrogen. To find out, they took a closer look at the material in which the moss grew and to their surprise found plenty of nutrients in it, including nitrogen. More information:center_img Antarctic Moss. Image: ANSTO Citation: Antarctic moss found able to survive due to ancient penguin colony guano (2012, July 6) retrieved 18 August 2019 from https://phys.org/news/2012-07-antarctic-moss-survive-due-ancient.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. Explore furtherlast_img read more

A manmade material that mimics the curling of the mimosa leaflet

first_img Play Static self-assembling properties of circular-shaped Janus bilayer demonstrating artificial tropism in response to a microdroplet. Credit: Wong et al. Sci. Adv. 2016; 2 : e1600417 PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen In addition to providing a roadmap for the development of a new class of self-organizing materials, the team believes their material could be used in a wide variety of applications, ranging from sensors built into clothes (which could self-activate when exposed to sweat) to sensors made for responding to other bodily fluids. It might even prove suitable for harvesting water from fog or for creating micro-robotic devices programmed by shape. PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen Researchers create tiny pump that provides continuous and spontaneous antigravity water delivery (Phys.org)—A combined team of researchers from the Australian National University and City University of Hong Kong has created a material that is capable of mimicking the action of a mimosa leaflet when it is touched. In their paper published in the journal Science Advances, the team describes their material and how it reacts when a drop of liquid is deposited onto its surface. PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen © 2016 Phys.org Explore furthercenter_img More information: W. S. Y. Wong et al. Mimosa Origami: A nanostructure-enabled directional self-organization regime of materials, Science Advances (2016). DOI: 10.1126/sciadv.1600417AbstractOne of the innate fundamentals of living systems is their ability to respond toward distinct stimuli by various self-organization behaviors. Despite extensive progress, the engineering of spontaneous motion in man-made inorganic materials still lacks the directionality and scale observed in nature. We report the directional self-organization of soft materials into three-dimensional geometries by the rapid propagation of a folding stimulus along a predetermined path. We engineer a unique Janus bilayer architecture with superior chemical and mechanical properties that enables the efficient transformation of surface energy into directional kinetic and elastic energies. This Janus bilayer can respond to pinpoint water stimuli by a rapid, several-centimeters-long self-assembly that is reminiscent of the Mimosa pudica’s leaflet folding. The Janus bilayers also shuttle water at flow rates up to two orders of magnitude higher than traditional wicking-based devices, reaching velocities of 8 cm/s and flow rates of 4.7 μl/s. This self-organization regime enables the ease of fabricating curved, bent, and split flexible channels with lengths greater than 10 cm, demonstrating immense potential for microfluidics, biosensors, and water purification applications.Press release Citation: A man-made material that mimics the curling of the mimosa leaflet (2016, June 27) retrieved 18 August 2019 from https://phys.org/news/2016-06-man-made-material-mimics-mimosa-leaflet.html Play Mimosa Origami assembly of the Janus bilayer strips performing double right-angle turns on a superhydrophobic PS-PDMS substrate. Credit: Wong et al. Sci. Adv. 2016; 2 : e1600417 Play Modular microfluidics: Janus-based Mimosa Origami strips with double-ended bulbs on a superhydrophobic PS-PDMS substrate showing in-channel droplet mixing. Credit: Wong et al. Sci. Adv. 2016; 2 : e1600417 Journal information: Science Advances As the researchers note, nature is filled with examples of living systems that react to stimuli by engaging in self-organization behaviors. One such example is the fern-like mimosa plant, it has multiple leaflets along individual twigs that are each independently sensitive to touch—such stimuli (such as children over the generations having some fun with their friends) causes the leaflet to curl up into a hollow tube shape resembling a very small straw. Developing materials with similar characteristics is highly desirable because it allows for creating unique products, such as very low power sensors.In this new effort, the researchers created the new material by fashioning stacks of multi-function layers of a Janus nanoparticle based material (offering opposite hydrophilic-hydrophobic properties) to a bottom layer made of polyvinyl chloride microfibers. The result was a thin length of flat white material with a larger round formation at one end. When a liquid was dropped onto the round formation, the liquid was pushed, through self-action, by the material all the way to the other end—as it was pushed, the material curled from one end to the other, resulting in what looked like an ordinary straw. The researchers report that the action was fast, taking just 33 milliseconds to get started. They note also that the self-action was reversible as well—as the material dried, it flattened. Play Modular microfluidics: Janus-based Mimosa Origami strips at a T-junction, showcasing double-ended split for potential in multichannel capabilities. Credit: Wong et al. Sci. Adv. 2016; 2 : e1600417 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

Dancing on strains of poetry

first_imgSufi Kathak Foundation presents under the 22 Khwaja Project series, a programme dedicated to the Sufi Saint Hazrat Deva Sharif ‘Bedam Shah Warsi’, writing under the pen name of Bedam whose shrine is situated in a small village – Dewa of Barabanki, Lucknow, Uttar Pradesh.The programme  features Sufi Kathak by Manjari Chaturvedi to Sufi Music, performed by Khanqahi Qawwals, Janaab Noorul Hasan and Janaab Arshad Hussian Chisty from Awadh.Hazrat Deva Sharif popularly known as Hazrat Bedam Shah Warsi of Sarkar Waris Pak was a Sufi saint from Dewa, a small village situated in Barabanki, India, who was the successor to the Qadriyya -Razzakiyya Silsila. Also Read – ‘Playing Jojo was emotionally exhausting’Some Hindus held him in high esteem and regarded him as a perfect Sufi and a follower of Vedant Hindus. Shah was popular with English-educated youth and English-speaking men flocked to him and sat at his feet. He was the first Sufi Darvesh to visit Europe and to have attract English-speaking followers. Manjari Chaturvedi is the creator and the only performing artist of Sufi Kathak. Conceptualised and created by Manjari, Sufi Kathak has taken 13 years of her intense work in Sufi music and classical dance.   Also Read – Leslie doing new comedy special with NetflixIntroducing the mystique of Sufism in dance, she traveled to countries like Egypt, Kyrgyzstan, Uzbekistan, Turkmenistan, and Tajikistan and worked with artists from Iran, Turkey and Morocco to study the music and dance forms related with Sufi thought. The Sufi qawwali musicians that will perform, trace their roots to traditional Sufi thought and music. The proposed Qawwal goups from Awadh Uttar Pradesh are led by Janaab Nurul Hassan, and Janaab Arshad Hussain Chishty representing the unique syncretic traditions of the Ganga-Jamuni tehzeeb of Awadh, singing the poetry of Hazrat Bedam Shah Warsi.last_img read more

Bengal to push for GST exemption up to Rs 50 lakh Mitra

first_imgKolkata: West Bengal would try to prevail upon the GST Council for giving exemption to businesses having an annual turnover of up to Rs 50 lakh, the state’s Finance Minister Amit Mitra said today. At present, the exemption limit for GST is for businesses having an annual turnover of Rs 20 lakh or less. “Let the GST stabilise first. It has not yet stabilised as matching of invoices with vouchers was being done manually,” Mitra said at a meeting of garment manufacturers and traders here. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killed He said the implementation of the new tax regime was done in a hurry, and the GST network had not been able to upload the GSTR2 form online yet for matching vouchers with invoices done through the GSTR1 (already uploaded online). “The exemption limit can be raised gradually,” he said. Mitra also announced that requirement of e-way bills for workers within the state was no longer needed. This, he said, would apply to the garment manufacturers in West Bengal. Also Read – Naihati: 10 councillors return to TMC from BJP “The state government will help the industry (garment) to get more organised so that better margins are realised,” the minister said. Mitra said the state had already formed a JV with the National Institute of Design (NID) of Ahmedabad for a design centre in West Bengal, and efforts would be made for designing of textiles as well. He stressed upon the need for upgradation of the quality of garments and refrain from using ‘azo-dyes’, which bar the manufacturers from exporting to European countries.last_img read more

Uproot BJP from state says Abhishek in firebrand speech against saffron party

first_imgBALURGHAT: Trinamool Congress MP and youth wing president Abhishek Banerjee has appealed to the public to uproot BJP from the soil of Bengal in the upcoming Parliamentary Elections in 2019.Addressing a rally at Dishari Ground here in Balurghat, Banerjee said: “In the Left regime, we heard the names like Hat Kata Dilip, Kan Kata Dilip (nicknames of popular Left-backed goons during the party’s rule in Bengal). Now, the people of Bengal are hearing the name of BJP’s Dilip Ghosh, who is already popular for his abusive languages. The saffron brigade has no control over him. If our leader Mamata Banerjee instructs us, no one can find a single flag of BJP across Bengal.” Also Read – Rain batters Kolkata, cripples normal lifeAttacking the party at the Centre, Banerjee said: “BJP divides people using religion. This is nothing but petty politics through which BJP is trying to polarise voters. But Bengal’s soil is different, where people will never entertain such devastating politics.”Criticising Prime Minister Narendra Modi for his role in the attack on Trinamool and party supremo Mamata Banerjee, the youth wing president said: “Seven births are not enough for Modi to oust Mamata Banerjee from Bengal. The Chief Minister, during her two-term tenure, has undertaken a plethora of development projects like Sabuj Sathi, Kanyashree, Shikshashree, Yubasree and many more. Bengal has been running peacefully under her guidance and ruling but there is total anarchy and unrest everywhere else for the misrule of BJP in the Centre.” Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedBanerjee also compared the Prime Minister with Gabbar Singh, a popular villain from the 70s Bollywood film Sholay.”We are ready to fight with the communal forces in the 2019 Lok Sabha poll. BJP will never form the government there. Mamata Banerjee has set a target to defeat BJP. We will win all 42 seats here. Bengal is the soil of Matangini, Ramakrishna, Swami Vivekananda and Rabindranath. Our integrity is great but nowadays we are hearing only Jai Sree Ram,” Banerjee said. Attacking ‘Aadhaar’, Banerjee said: “The Central government has already created panic among people in the name of Aadhaar card. People are now scared of it.”Attacking the Left Front, Banerjee said: “CPI-M and other Left parties are now taking shelter under BJP’s umbrella for existence. They have no ideology at all. People have already rejected them for misrule from Bengal.”Veteran Trinamool leaders like Firhad Hakim, Subrata Bakshi, Chandrima Bhattacharjee, Arpita Ghosh and Biplab Mitra echoed Banerjee and said people are now ready to oust BJP from the Centre, while Trinamool will win all 42 seats and will take the lead role to form government at the Centre in 2019.last_img read more