Month: August 2019
© 2011 PhysOrg.com (PhysOrg.com) — A thin sheet of plastic has been making headlines at Princeton as a magical flying carpet, after the publication of a paper describing experiments by the team with their prototype sheet of plastic that uses piezoelectric actuators and sensors to move. The sensors and conducting threads create “ripples” of air moving front to back of the sheet, and the sheet is propelled into the air. Citation: ‘Flying carpet’: Princeton team’s plastic sheet can hover above ground (w/ video) (2011, October 1) retrieved 18 August 2019 from https://phys.org/news/2011-10-carpet-princeton-team-plastic-sheet.html More information: Traveling wave-induced aerodynamic propulsive forces using piezoelectrically deformed substrates, Appl. Phys. Lett. 99, 114102 (2011); doi:10.1063/1.3637635AbstractWe use integrated piezoelectric actuators and sensors to demonstrate the propulsive force produced by controllable transverse traveling waves in a thin plastic sheet suspended in air above a flat surface, thus confirming the physical basis for a “flying” carpet near a horizontal surface. Experiments are conducted to determine the dependence of the force on the height above the ground and the amplitude of the traveling wave, which qualitatively confirm previous theoretical predictions.via BBC Ironing out the causes of wrinkles Explore further The creator, graduate student Noah Jafferis, and team described their device and findings in Applied Physics Letters, which published their article online earlier this month.”We use integrated piezoelectric actuators and sensors to demonstrate the propulsive force produced by controllable transverse traveling waves in a thin plastic sheet suspended in air above a flat surface, thus confirming the physical basis for a ‘flying’ carpet near a horizontal surface,” wrote the three authors, Noah Jafferis, Howard Stone, and James Sturm. “Experiments are conducted to determine the dependence of the force on the height above the ground and the amplitude of the traveling wave, which qualitatively confirm previous theoretical predictions.” The undulating ripples allow the sheet to move at a speed of a centimeter per second, and Jafferis believes it should be possible to increase the speed to about a meter per second.An earlier paper written by Harvard Professor Lakshminarayanan Mahadevan inspired Jafferis to look into his hovering plastic sheet project shortly after starting his doctoral studies. Jafferis at the time had been on another project, printing electronic circuits with nano-inks. Instead he turned to the plastic sheet project and spent two years working on sensors and performance improvements. A BBC interviewer was told by Sturm that it was not easy to control the sheet’s behavior as it deformed at high frequencies.Even though news reports are referring to the sheet as a flying carpet, weaknesses in propulsion and lift hardly make the device comparable to magic carpets. Jafferis is careful to point out that flying should be in quotes because the object does not fly, nor does it go fast. The sheet hovers above the ground as electric ripples flow, moving air along its underside.Jafferis points out that the prototype’s tiny conducting threads anchor it to heavy batteries. On the development agenda is a solar-powered upgrade that could enable it to fly over large distances.Applications for such a device, according to reports, might include a planet Mars rover. Prof Mahadevan looks forward to sophisticated improvements in the near future, suggesting the approach could progress to “mimicking the beautiful two-dimensional undulations of the skate or manta ray.” 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.
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 Journal information: Physical Review Letters New theory suggests some black holes might predate the Big Bang For many years theoretical physicists have believed that the universe came about as a result of a single Big Bang event—Einstein’s theories suggested it was so. The problem with this line of thinking however, is that the theory of general relativity can’t describe what came before the singularity, which should exist at the point in time just before the Big Bang. Theory also suggests that a similar singularity should exist at the center of black holes, but again, general relativity fails to describe them properly. Worse, there is the problem of the information loss paradox—if something falls into a black hole and is eventually squeezed to a singularity, what happens to the information it contained? Big Bang physicists can’t say.To address these problems, Abhay Ashtekar and his team at Pennsylvania State University, back in 2006, came up with a theory known as loop quantum gravity. They suggested that instead of a singularity existing just before the Big Bang, there was the remains of a crunched down universe that had existed prior to the one that exists now. The universe didn’t just Big Bang itself into existence from nothing, they said, instead there is an infinite loop where a universe shrinks down to a very tiny spot, then explodes in a Big Bang, then shrinks down again, over and over again forever—hence the use of the term “loop” in the theory. Since that time, some in the field have begun to refer to the theory as the Big Bounce, to replace the name Big Bang.In this new effort Gambini and Pullin applied LQG to a simplified model of a black hole. Their experiment showed that everything that was pulled into the black hole didn’t compress to a singularity after all—instead it was compressed to a certain small size, then was spit out in another part of the universe or into another universe entirely.Because their model worked so well, the two suggest that it would likely work with real black holes as well. If this new theory is correct, they note, it would do away with the information loss paradox and open the door to the possibility of black holes being portals to other universes. © 2013 Phys.org (Phys.org) —Physicists Rodolfo Gambini and Jorge Pullin of University of the Republic in Montevideo, Uruguay, and Louisiana State University respectively, have applied the theory of Loop Quantum Gravity (LQG) to a simplified black hole. In so doing, as they describe in their paper published in the journal Physical Review Letters, they suggest that instead of a singularity existing at its center, there is a portal to another universe. Citation: Theorists apply loop quantum gravity theory to black hole (2013, May 31) retrieved 18 August 2019 from https://phys.org/news/2013-05-theorists-loop-quantum-gravity-theory.html More information: Loop Quantization of the Schwarzschild Black Hole, Phys. Rev. Lett. 110, 211301 (2013) prl.aps.org/abstract/PRL/v110/i21/e211301AbstractWe quantize spherically symmetric vacuum gravity without gauge fixing the diffeomorphism constraint. Through a rescaling, we make the algebra of Hamiltonian constraints Abelian, and therefore the constraint algebra is a true Lie algebra. This allows the completion of the Dirac quantization procedure using loop quantum gravity techniques. We can construct explicitly the exact solutions of the physical Hilbert space annihilated by all constraints. New observables living in the bulk appear at the quantum level (analogous to spin in quantum mechanics) that are not present at the classical level and are associated with the discrete nature of the spin network states of loop quantum gravity. The resulting quantum space-times resolve the singularity present in the classical theory inside black holes.via Synopsis This artist’s concept shows a galaxy with a supermassive black hole at its core. The black hole is shooting out jets of radio waves. Image credit: NASA/JPL-Caltech
Páramo-like vegetation with a high diversity of mostly endemic Cora species is also found in the Central American cordilleras in Costa Rica. Credit: Robert Lücking A team of researchers with members from the U.S. and several South American countries has found that a type of lichen that grows in several parts of Central and South America consists of at least 126 species of fungi and possibly as many as 400. As the team notes in their paper published in Proceedings of the National Academy of Sciences, until very recently, the lichen was believed to have just one species of fungus. The Galapagos Islands harbor at least two endemic species of Cora. Credit: Robert Lücking Lichen evolved on two tracks, like marsupials and mammals More information: A single macrolichen constitutes hundreds of unrecognized species, Robert Lücking, PNAS, DOI: 10.1073/pnas.1403517111AbstractThe number of Fungi is estimated at between 1.5 and 3 million. Lichenized species are thought to make up a comparatively small portion of this figure, with unrecognized species richness hidden among little-studied, tropical microlichens. Recent findings, however, suggest that some macrolichens contain a large number of unrecognized taxa, increasing known species richness by an order of magnitude or more. Here we report the existence of at least 126 species in what until recently was believed to be a single taxon: the basidiolichen fungus Dictyonema glabratum, also known as Cora pavonia. Notably, these species are not cryptic but morphologically distinct. A predictive model suggests an even larger number, with more than 400 species. These results call into question species concepts in presumably well-known macrolichens and demonstrate the need for accurately documenting such species richness, given the importance of these lichens in endangered ecosystems such as paramos and the alarming potential for species losses throughout the tropics. Journal information: Proceedings of the National Academy of Sciences © 2014 Phys.org Lichen is an organism that exists as a partnership between a fungus and photosynthetic partner—it’s a photobiont. The main mass of any given lichen generally consists of fungal filaments which host algal cells. In the study in South America, the researchers looked at Dictyonema glabratum, which recently was divided into two separate genera, (Cora and Corella) with initial analysis suggesting 16 distinct species of fungi. D. glabratum (lichen are named after the fungal component) is considered to be ecologically important to South America as it is one among many lichen that fix atmospheric nitrogen into the soil, which makes them natural fertilizers. D. glabratum is generally small, about the size of human fist, and grows in curly masses around other objects, such as tree trunks. In this new effort the researchers expanded on genetic research conducted by other teams that have found that some species of organisms are actually more than one—African elephants are actually two species, for example and there are two distinct species of the Nile crocodile and four species of Killer whales. Curious after the reclassification of D. glabratum, the research team used DNA barcoding and performed phylogenetic analysis on 356 samples and found an astonishing 126 different species of fungi.The team next created a grid map of the range of the lichen, from Central and South America to the Caribbean islands and used it to create a computer model—a simulation from it predicted that it’s likely the true number of fungi species in the lichen is close to 452. In retrospect, the lichen may not have been hiding its many species, as evidence offering clues was abundant—they come in several colors, grow on several different surfaces and some even have unique features such as crinkled margins or fine hairs. Researchers have likely missed such clues, the researchers note, due to most studies being conducted using specimens that had been dried and stored for such purposes. This recently described species of Cora is exclusively epiphytic and often forms large individuals. Credit: Robert Lücking Explore further Citation: South American lichen found to have 126 different species of fungi (2014, July 1) retrieved 18 August 2019 from https://phys.org/news/2014-07-south-american-lichen-species-fungi.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 new flow cell produces an average power density of 0.82 W/m2, which is almost 200 times higher than values obtained using previous similar methods. Although it is not yet clear whether the process could be economically viable on a large scale, the early results appear promising and could be further improved with future research.The scientists, Taeyong Kim, Bruce E. Logan, and Christopher A. Gorski at The Pennsylvania State University, have published a paper on the new method of CO2-to-electricity conversion in a recent issue of Environmental Science & Technology Letters.”This work offers an alternative, simpler means to capturing energy from CO2 emissions compared to existing technologies that require expensive catalyst materials and very high temperatures to convert CO2 into useful fuels,” Gorski told Phys.org.While the contrast of gray-white smoke against a blue sky illustrates the adverse environmental impact of burning fossil fuels, the large difference in CO2 concentration between the two gases is also what provides an untapped energy source for generating electricity.In order to harness the potential energy in this concentration difference, the researchers first dissolved CO2 gas and ambient air in separate containers of an aqueous solution, in a process called sparging. At the end of this process, the CO2-sparged solution forms bicarbonate ions, which give it a lower pH of 7.7 compared to the air-sparged solution, which has a pH of 9.4. After sparging, the researchers injected each solution into one of two channels in a flow cell, creating a pH gradient in the cell. The flow cell has electrodes on opposite sides of the two channels, along with a semi-porous membrane between the two channels that prevents instant mixing while still allowing ions to pass through. Due to the pH difference between the two solutions, various ions pass through the membrane, creating a voltage difference between the two electrodes and causing electrons to flow along a wire connecting the electrodes.After the flow cell is discharged, it can be recharged again by switching the channels that the solutions flow through. By switching the solution that flows over each electrode, the charging mechanism is reversed so that the electrons flow in the opposite direction. Tests showed that the cell maintains its performance over 50 cycles of alternating solutions.The results also showed that, the higher the pH difference between the two channels, the higher the average power density. Although the pH-gradient flow cell achieves a power density that is high compared to similar cells that convert waste CO2 to electricity, it is still much lower than the power densities of fuel cell systems that combine CO2 with other fuels, such as H2. However, the new flow cell has certain advantages over these other devices, such as its use of inexpensive materials and room-temperature operation. These features make the flow cell attractive for practical applications at existing power plants.”A system containing numerous identical flow cells would be installed at power plants that combust fossil fuels,” Gorski said. “The flue gas emitted from fossil fuel combustion would need to be pre-cooled, then bubbled through a reservoir of water that can be pumped through the flow cells.”In the future, the researchers plan to further improve the flow cell performance.”We are currently looking to see how the solution conditions can be optimized to maximize the amount of energy produced,” Gorski said. “We are also investigating if we can dissolve chemicals in the water that exhibit pH-dependent redox properties, thus allowing us to increase the amount of energy that can be recovered. The latter approach would be analogous to a flow battery, which reduces and oxidizes dissolved chemicals in aqueous solutions, except we are causing them to be reduced and oxidized here by changing the solution pH with CO2.” © 2017 Phys.org Chemists present an innovative redox-flow battery based on organic polymers and water Explore further (Phys.org)—Researchers have developed a type of rechargeable battery called a flow cell that can be recharged with a water-based solution containing dissolved carbon dioxide (CO2) emitted from fossil fuel power plants. The device works by taking advantage of the CO2 concentration difference between CO2 emissions and ambient air, which can ultimately be used to generate electricity. The pH-gradient flow cell has two channels: one containing an aqueous solution sparged with carbon dioxide (low pH) and the other containing an aqueous solution sparged with ambient air (high pH). The pH gradient causes ions to flow across the membrane, creating a voltage difference between the two electrodes and causing electrons to flow along a wire connecting the electrodes. Credit: Kim et al. ©2017 American Chemical Society Journal information: Environmental Science & Technology Letters Citation: Battery can be recharged with carbon dioxide (2017, February 9) retrieved 18 August 2019 from https://phys.org/news/2017-02-battery-recharged-carbon-dioxide.html More information: Taeyoung Kim et al. “A pH-Gradient Flow Cell for Converting Waste CO2 into Electricity.” Environmental Science & Technology Letters. DOI: 10.1021/acs.estlett.6b00467 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.
Journal information: Science More information: Joshua Sokol. New tactics clash on speed of expanding universe, Science (2019). DOI: 10.1126/science.365.6451.306 © 2019 Science X Network Credit: CC0 Public Domain Estimates of its value based on studying the light emitted from the Big Bang differ from those calculated using data from supernovas. Put a simpler way, researchers using data from studies involving the oldest history of the universe have calculated a different value for the Hubble Constant than those involved in studying more recent activity. And the reason it has become such a hot topic is because if a reasonable reason for the differences cannot be found, scientists in the field might have to completely rethink how the universe works.The basis of the debate began back in the 1920s when Edwin Hubble noted that the farthest objects in the universe appear to be moving away from one another faster. Theorists suggested a fixed number could be used to express just how fast the universe was expanding—thus the Hubble Constant was born. It is defined as the rate of expansion of the universe. As its name implies, theory suggests it is a single unchanging number. But experiments to find the true value of the Hubble Constant have delivered mixed results. One technique involves using data from devices that measure the cosmic microwave background, which is believed to be light emitted not long after the Big Bang. Such studies have shown the Hubble Constant to be 67.4 km/s/Mpc, with an error rate of just 0.5 km/s/Mpc. Meanwhile, other studies involving use of data from supernova have found the constant to be 74.0 km/s/Mpc—a far cry from the first error rate. Clearly both cannot be correct, unless there was something odd going on during the early expansion of the universe. Some physicists believe it is possible that there was a different kind of dark energy pushing the universe apart back then, accounting for the difference.In any case, the researchers at the recent meeting voted against calling it a crisis, suggesting that few in the field are ready to throw out major theories underlying the understanding of how the universe works—at least not right now. Explore further Citation: Scientists debate the seriousness of problems with the value of the Hubble Constant (2019, July 31) retrieved 18 August 2019 from https://phys.org/news/2019-07-scientists-debate-seriousness-problems-hubble.html New Hubble constant measurement adds to mystery of universe’s expansion rate Astronomers, astrophysicists and particle physicists gathered recently at the Kavli Institute for Theoretical Physics at the University of California to discuss the seriousness of differing measurements of the Hubble Constant. They met to talk about a problem that has become a major concern in astrophysics—figuring out how fast the universe is actually expanding. 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.
Kolkata: A 45-year-old man died after being hit by a speeding bus at Taratala on Thursday afternoon while in a separate accident a 6-year-old girl was crushed to death by a truck in Jalpaiguri early on the day.In both the cases, police have seized the vehicles. They have arrested the bus driver in connection with the accident while in the other case the truck driver has been absconding since the accident took place in Jalpaiguri.According to police, the victim, Vinay Ram (45), was standing in front of a lamp post situated on the pavement near Taratala Bridge when the accident happened. Police suspect that the lamp post fell on the victim after it was hit by the bus. Some passengers travelling in the bus suffered minor injuries in the incident. According to preliminary investigation, police suspect that the driver had a brake fail and the vehicle eventually hit the lamp post and then a road side tree. Also Read – Heavy rain hits traffic, flightsSome locals, however, told the police that the bus knocked him down after hitting the lamp post. Police have started a probe in this regard. The accused bus driver is being interrogated. Police said a Kolkata bound bus from Diamond Harbour was running at a high speed when the driver lost control over the vehicle. He applied sudden brake but failed to control it. As a result, the speeding bus ran over the pavement and hit the lamp post and then a tree. Some of the passengers were also admitted to a hospital who received injuries during the incident. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedThe incident triggered traffic jam on Diamond Harbour Road. Locals also staged a demonstration on the spot protesting against rash driving of the vehicles. The situation was later brought under control by a huge contingent of police. The victim died on spot. Police recovered the body and sent it for postmortem.In the other incident, Nikita Roy (6), a resident of Moynaguri road area was trying to cross National Highway 31 on Thursday morning when a speeding truck hit her near a petrol pump. The truck driver suddenly applied the brake to save the girl but he failed to do so as the vehicle was running at a high speed. Locals rushed to the spot and rushed the critically injured victim to Jalpaiguri Super specialty hospital where the doctors pronounced her brought dead. Police have already seized the vehicle and conducting raids to nab the driver.
Kolkata: Mystery shrouds the death of a woman who succumbed to her burn injuries when she was taken to a hospital in East Midnapore.The victim’s family members alleged that she was tortured and set on fire. However, the police were told by her in-laws that she set herself on fire on Saturday night and her husband also received burn injuries while trying to save her.The incident took place in Pataspur area of East Midnapore on Sunday morning. A senior police officer from the district said they have started an unnatural death case and they would probe into all possible angles of the incident. Also Read – Heavy rain hits traffic, flightsThe woman was admitted to the hospital on Sunday morning and she succumbed to her injuries on Friday morning. Allegations against the victim’s in-laws that they had set the woman on fire as her parents failed to give them money have also been levelled.The police officer said they haven’t received any such complaint yet. But they have initiated a case to probe in this connection. They will be taking statements of the victim’s parents and at the same time, they would try to find whether there was any foul play by the victim’s in-laws. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedAnother police officer said even if they consider that the woman had committed suicide, then there must be a reason behind it. Police are trying to know what had happened on Thursday night that led to the incident.According to police, the victim Maya Mondal (45) was found in charred condition by the locals at Patashpur II close to Pariharpur jungle. Police are not also ruling out the possibility of suicide. The victim had married one Chandan Mondal a few years ago and they have no child.
Kolkata: Criminal Investigation Department (CID) on Tuesday collected samples of carcass meat from the cold storage at Narkeldanga and sent it for tests by food analysts. It may be mentioned that after initiating the probe, the South 24-Parganas police had came to know about the cold storage at Narkeldanga and had conducted a raid on April 26. During the raid, the police had recovered a huge quantity of meat. Samples were then sent to laboratories to carry out necessary tests. Also Read – Heavy rain hits traffic, flightsThe case was later taken up by CID and the investigating officers felt the necessity of carrying out another test. So, concerned officers of CID, along with officials from the Kolkata Municipal Corporation (KMC), went to collect the samples.According to a senior officer of CID, the tests will be carried out by a food analyst of the civic body.The police had come to know about the cold storage at Narkeldanga after interrogating Sunny, who was arrested from Bihar in connection with the carcass meat case. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedLater, the police also came to know that Biswanath Ghorui, alias Bishu, was the kingpin of the carcass meat selling racket. He was also arrested and from him, the police had come to know about another cold storage in Kolkata itself, where meat was stored. CID officers had raided the cold storage and confiscated six tonnes of meat.The CID officers are in search of the owner of the cold storage, as he would be able to reveal from where the packaged meat was brought and also the name of the places where the same was sold. The police had suspected that the same was exported to other states and some of the neighbouring countries as well. The state government has also formed a high powered committee headed by Chief Secretary Malay De, to take necessary steps to completely uproot the menace. The first meeting of the committee was held in Nabanna.
Chennai-born Bharatanatyam dancer and writer Tulsi Badrinath whose roots lie in Uttar Pradesh