Wind power is one of the more feasible renewable energy sources. Image credit: Kichigai Mentat Citation: 5 Feasible Renewable Energy Sources (2009, May 8) retrieved 18 August 2019 from https://phys.org/news/2009-05-feasible-renewable-energy-sources.html Do the benefits of renewable energy sources stack up? Explore further One would expect that — over time — the costs associated with renewable energy would go down. With fossil fuels, costs can only go up as the un-renewable sources dwindle and become more scarce even as demand rises. Here are 5 feasible renewable energy sources that could be developed to help meet world energy needs:1. Solar: This is perhaps the most recognized renewable energy source. Energy from the sun is captured using cells made from special materials (silicon is quite popular right now) and then converted into electricity. The biggest factor in solar cell production is cost. However, with technological advancements solar is becoming more cost efficient, and high efficiency solar cells are being developed. This is important, since high efficiency cells are hard to come by. New materials are providing solar cells that are easier to transport and install. Flexible solar cells can be used for residential use, and building solar arrays is becoming popular. One of the main factors in efficiency is the fact that solar panels only generate electricity during daylight hours, and can be hampered by cloudy conditions or pollution. Some sort of storage is needed in order to make full use of solar power.However, there are environmental impacts associated with building arrays, since they take up a great deal of room (which is why deserts are being considered — but still ecological impacts are a reality). In some areas, power companies are toying with the idea of renting rooftops and installing solar panels. This way companies could generate renewable energy that would be theirs, customers could see their costs decrease, and homeowners would not have to pay for installation. Warehouses would be targeted in larger areas. These types of projects could help overcoming the cost-efficiency hurdle, while reducing the environmental impact of large solar installations. 2. Wind: Wind power is growing rapidly, and is becoming a well-recognized renewable energy resource. Using wind power to turn turbines that generate electricity can provide a cheap source of energy. Building and maintaining equipment could provide thousands of jobs and cost-efficient and clean electricity. Wind farms, however, are not particularly popular. They can impact local environment and wildlife, and even provide noise pollution. Additionally, many people feel that the equipment used obstructs scenic views. It is possible, however, to construct wind turbines in various sizes. They can be made for single residential use, and they can be constructed on a large scale as well. Wind power could be used in areas where there is a great deal of wind, and a lot of open spaces. Technology is making this mode of renewable energy more efficient and less intrusive, but many still feel that there is a long way to go with wind power.3. Geothermal: Geothermal energy is extracted from the natural processes of the earth. A great deal of heat is created below Earth’s surface, and efforts are being made to extract and use this power. While the ancient Romans knew about and used geothermal heating, now Earth’s processes are being used to generate electricity — going beyond space heating. Geothermal power does not put off greenhouse gases (although some harmful gases from deep in the earth would be released — and need to be contained), and it is reliable. However, it can only be used in areas where there is tectonic activity. Unfortunately, drilling is involved with geothermal extraction. Additionally, exploration is rather expensive. The costs of starting a geothermal plant are quite high at the outset, including the piping that would need to be laid and all the other costs, although a geothermal operation takes up less surface space than a power plant that uses coal or oil. Fuel is not necessary for a geothermal plant at all. However, once a successful geothermal plant is established, the long-term cost-efficiency usually makes up for the initial cost outlay.4. Water: We have been studying water-based renewable energy for quite some time. Hydroelectricity has been a source of energy for years. However, even though the energy production process does not put off pollution, there are other environmental concerns associated with the damming of rivers and ecological impacts stemming from this practice. But hydroelectric power remains one of the more cost-efficient means of generating renewable energy.Other water sources are being considered as well. Tidal power is being developed right now as an energy alternative. Tidal generators placed underwater work in a similar fashion to wind turbines, only they are turned by currents. While considered environmentally friendly, tidal power will be difficult and expensive to develop, since it involves placing generators at the bottom of the ocean. These “underwater wind farms” are also likely to have impacts on sea life.5. Nuclear: Perhaps the most controversial form of renewable energy is nuclear energy. Electricity is produced from the energy released by nuclear reactions. While fission (splitting) is the main source used today, interest continues in developing cold fusion. Currently, though, power plants generating power using nuclear fission are among the safest plants. They also generate power without emitting pollution. In Europe, France benefits greatly as its nuclear energy produces the cheapest electricity (according to 60 Minutes).The biggest drawback that many see with nuclear energy is the waste. Radioactive waste is a concern, since it is a health hazard and if stored improperly can leach into soil and groundwater. However, with the right kind of processes, it is possible to recover the waste from the reactions, reclaiming it for further power generation. With technological advancements, it could be theoretically possible to reclaim up to 95% of the waste from initial reactions. Right now, though, France leads in nuclear waste recycling with only 28%. Another issue is fear of sabotage that could result in large-scale contamination. However, nuclear energy is the probably the fastest method that could be put into practice for energy independence from fossil fuels.Implementing Renewable EnergyAll of these processes would require expense up front. Research and technological developments to advance the efficiency of renewable energy is expense. Producing the equipment would require a large initial capital outlay. Additionally, there are some environmental concerns beyond air pollution and global warming with any of these processes. However, it is thought that the environmental impacts long-term would still be less than those of continuing to use fossil fuels. Additionally, cost-efficiency would increase, and overall energy costs would be expected to fall long-termNo one of these renewable energy sources could effect a change, however. It would require coordinated implementation of a variety of alternative strategies to replace the energy we get from fossil fuels. Assessments of which types of energy would work best in different locales would be required, and a great deal of planning would be needed for a successful implementation.© 2009 PhysOrg.com (PhysOrg.com) — President Barack Obama has made no secret of his desire to develop a “green economy” that includes renewable energy projects meant to benefit the environment. He has said that part of the economic recovery in the U.S. will come from money for, and jobs created by, renewable energy projects. Around the world, politicians, businesses and scientists are developing the technology that could improve the cost-efficiency of renewable energy. 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 The researchers, led by Professor Ib Chorkendorff from the Technical University of Denmark, with coauthors from institutions in Denmark and the US, have published their study in a recent issue of Nature Materials.As the researchers explain in their study, producing fuels from sunlight could lead to the development of a sustainable energy system, without the need for fossil fuels. Sunlight can be used to produce a variety of carbon-based solar fuels such as methanol and methane, but the simplest solar fuel to produce is hydrogen. In a typical solar hydrogen system, photovoltaic panels turn sunlight into electricity that is then used to extract hydrogen from water. Scanning electron micrograph of silicon pillars. Image credit: Yidong Hou, CINF, DTU Physics (photo). Christian D. Damsgaard, Thomas Pedersen, Ole Hansen, DTU Nanotech, DK-2800 Kongens Lyngby, Denmark. Illustration of the chemical solar cell. Image credit: Adapted from Lewis, N. S. & Nocera, D. G. Powering the planet: Chemical challenges in solar energy utilization. Proc. Natl. Acad. Sci. USA 103, 15729-15735 (2006) and Grey, H. B. Powering the planet with solar fuel. Nature Chem. 1, 7 (2009). After applying small dots of the molybdenum sulfide onto the photocathode part of the pillars, the researchers tested the modified chemical solar cell. They found that, when the cell was exposed to light, it generated hydrogen with a solar-to-hydrogen efficiency of greater than 10%, which is comparable to the efficiency when platinum was used instead.Serving as a HER catalyst, the new compound addresses only half of the water-splitting process. In the future, the researchers also hope to find a cheap, abundant material for an OER catalyst. Although they predict that this may be even more difficult than finding the HER catalyst material, they plan to use the same methods to approach this challenge. (PhysOrg.com) — By replacing catalysts made of expensive noble metals like platinum with cheaper, earth-abundant materials, researchers have taken a step toward enabling the large-scale production of hydrogen from sunlight and water. In a recent study, the researchers have demonstrated that catalysts made of molecular clusters based on molybdenum and sulphur can generate hydrogen from sunlight at rates comparable to those of platinum. 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. Play When the chemical solar cell is exposed to light, hydrogen bubbles appear. Image credit: CINF, Department of Physics, DTU. One type of solar hydrogen system is a chemical solar cell, which can harvest a large part of the solar spectrum and use it to generate hydrogen from water. Chemical solar cells consist of many pillars, with the top half of each pillar made of a photoanode that absorbs the blue part of the solar spectrum, and the bottom half made of a photocathode that absorbs the red part. When blue light is absorbed, it oxidizes water into oxygen and protons. The protons migrate through a membrane in which the pillars are embedded, ending up at the photocathode. As red light is absorbed, catalysts attached to the sides of the pillars reduce the protons to hydrogen.As the researchers explain, the system depends on two reactions: the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). In their study, the scientists focus exclusively on designing HER catalysts to perform the final step of reducing protons. Previously, platinum and other noble metals have been used as efficient HER catalysts, but they are too scarce and expensive for large-scale energy production. To find an alternative HER catalyst, the researchers investigated biological organisms that have enzymes that produce hydrogen. By analyzing these natural catalysts, the researchers identified the properties that made them efficient, and then searched for related compounds that might work in a chemical solar cell. This process of theory, computation, synthesis, and testing led them to molybdenum sulfide – an inexpensive and abundant compound. Copyright 2011 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. Citation: Cheap, abundant cathode material found for producing hydrogen fuel (w/ video) (2011, May 10) retrieved 18 August 2019 from https://phys.org/news/2011-05-cheap-abundant-cathode-material-hydrogen.html Hydrogen fuel tech gets boost from low-cost, efficient catalyst More information: Yidong Hou, et al. “Bioinspired molecular co-catalysts bonded to a silicon photocathode for solar hydrogen evolution.” Nature Materials. Advance Online Publication. DOI: 10.1038/NMAT3008Participating institutions:The Center for Individual Nanoparticle Functionality, CINF, www.cinf.dtu.dk Catalysis for Sustainable Energy, CASE, www.case.dtu.dkSLAC National Accelerator Laboratory, www.slac.stanford.edu SUNCAT, today.slac.stanford.edu/feature/2010/suncat.asp 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
(Phys.org)—Using a photon fission process, physicists have split a single photon into a pair of daughter photons and then split one of the daughter photons into a pair of granddaughters to create a total of three photons. All three photons, the scientists showed, share quantum correlations between their energies (corresponding to their momentums) and between their emission times (corresponding to their positions). The study marks the first experimental demonstration of energy-time entanglement of three or more individual particles, building on the original two-particle version proposed by Einstein, Podolsky, and Rosen (EPR) 77 years ago. Citation: Physicists extend entanglement in Einstein experiment (2012, December 6) retrieved 18 August 2019 from https://phys.org/news/2012-12-physicists-entanglement-einstein.html Building on these studies over the next several decades, physicists have demonstrated many different types of entanglement, which are defined by the number and type of objects that are entangled and the properties of the objects that are entangled. These properties can fit into one of two categories: discrete or continuous, which describe the variable’s domain. For example, spin is a discrete variable since its value can only be an integer or half-integer, while emission time is continuous. Entanglement has previously been demonstrated between the discrete variables of 14 ions and the continuous variables of three light beams, but until now entanglement among the continuous properties of three individual particles has remained an open challenge.”What is exciting about our work is that we can take the original arguments made by EPR for two particles and extend them to three particles,” Shalm said. “The kind of entanglement that EPR first proposed pertained to continuous variables, like position and momentum, as opposed to discrete variables, like polarization or spin. Discrete variables in photons have traditionally been easier to manipulate. With our system we finally have a viable way to explore the entanglement of continuous variables between three particles.”To achieve continuous-variable entanglement among three photons, the physicists split a photon into a pair of daughters using a process called cascaded spontaneous parametric downconversion. Since energy is conserved, each daughter photon has a frequency that is roughly half that of the pump photon. When one of the daughter photons is split, the two granddaughter photons each have a frequency that is about half that of the daughter photons. Although the frequency of each individual photon may vary slightly from exact halving, the total energy of the three photons combined is exactly equal to the energy of the pump photon. In addition, because the splitting process is instantaneous, the three photons must arrive at photon detectors at the same time.Under these production conditions, the three photons share strong spectral correlations and, in theory, possess genuine tripartite energy-time entanglement. This means that the energy values and the emission times of the three photons share correlations that are stronger than those allowed by classical physics.To verify that the three photons possess energy-time entanglement, the physicists had to confirm that the three photons violate a set of inequalities that are an extension of the EPR arguments for two particles. These tests require measuring and comparing the arrival times of the three photons at a single-photon detector. One way to do this is to directly measure each photon’s frequency; however, current technology doesn’t provide sufficient precision for direct frequency measurements. Instead, the scientists measured the frequency of the pump photon and ensured that energy was conserved in the downconversion process. They also used detectors to measure the arrival times of the photons, but noted that the detectors have a timing jitter of several hundred picoseconds that limited the precision. Even accounting for this uncertainty, the results showed that the three photons do indeed violate the EPR inequalities and are therefore energy-time entangled. Future improvements in detector precision would provide improvements in the measured values of the inequalities by over two orders of magnitude. In addition, new technologies to enhance the observed effects could potentially allow this scheme to be scaled up to larger photon numbers.In terms of applications, this entanglement scheme could be useful in quantum communications because it provides the opportunity to entangle multiple degrees of freedom, generating “hyper-entanglement.” If one of the entangled photons could be interfaced with an atomic storage medium while the other two photons are transmitted over telecom fibers to remote quantum nodes, then scientists could create new possibilities for storing and distributing quantum information. Other modifications of the scheme could lead to new fundamental tests of quantum mechanics.”Three particle states that are entangled in their continuous degrees of freedom may allow for a new class of tests for quantum mechanics that could further our understanding of quantum theory and entanglement,” Shalm said. “This is also an important technological step. It is a system that lets us exploit optical nonlinearities at the single-photon level. This may have important applications in creating the gates needed in a quantum computer, or in distributing quantum information over a network.”In the future, the scientists plan to try to combine the position and momentum entanglement among the three photons with more traditional types of entanglement based on angular momentum and polarization. This kind of combined entanglement could lead to the creation of hybrid quantum systems that possess multiple unique properties of light at the same time. Copyright 2012 Phys.org All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of Phys.org. Explore further Quantum physics mimics spooky action into the past 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: Nature Physics To verify entanglement among the three photons, the physicists measured the times that the photons arrived at a detector. This 2D histogram shows that groups of three photons are all localized to a small region, indicating strong correlations in the arrival times of the three photons. Image credit: L. K. Shalm, et al. ©2012 Macmillan Publishers Limited The physicists, from the University of Waterloo and the University of Calgary, have published their paper on three-photon energy-time entanglement in a recent issue of Nature Physics.As the physicists explain, this new form of entanglement is the three-photon version of the famous EPR correlations for continuous variables (e.g., position and momentum) between two particles. The EPR thought experiment, published in 1935, raised questions about the fundamental concepts underlying the young theory of quantum mechanics.”The Heisenberg uncertainty principle forbids one from simultaneously discovering both the position and momentum of a particle with arbitrary accuracy,” lead author Krister Shalm of the University of Waterloo told Phys.org. “EPR pointed out that, if you create a pair of entangled particles, it is possible to measure both the position and momentum of both of them with arbitrary precision. It is still impossible to learn both the position and momentum of each of the individual particles, but, instead, we can learn information about the total position and momentum they share. Entangled particles, in some sense, are the ultimate team players. They lose their own individual identity with all the information in the system contained in the correlations.”In the original experiment, EPR tried to demonstrate that the correlations between two particles were so strong that there must be some hidden parameter to explain them that quantum mechanics does not account for. This conclusion seemed to uncover some inadequacies in quantum mechanics.”The original arguments made by EPR in 1935 were designed to show that quantum mechanics, by itself, is not sufficient to describe reality,” Shalm said. “This inspired John Bell, who showed that if you take the arguments of EPR that relied on hidden variables to their logical conclusions, you arrive at a contradiction with quantum mechanics. Since then, much work has been devoted to using Bell’s work to test quantum mechanics, and extensions of the work have profoundly shaped our understanding of the quantum world.”
Citation: Researchers use microRNA to trap mutant viruses in the lab (2013, August 12) retrieved 18 August 2019 from https://phys.org/news/2013-08-microrna-mutant-viruses-lab.html © 2013 Phys.org More information: MicroRNA-based strategy to mitigate the risk of gain-of-function influenza studies, Nature Biotechnology (2013) DOI: 10.1038/nbt.2666AbstractRecent gain-of-function studies in influenza A virus H5N1 strains revealed that as few as three-amino-acid changes in the hemagglutinin protein confer the capacity for viral transmission between ferrets. As transmission between ferrets is considered a surrogate indicator of transmissibility between humans, these studies raised concerns about the risks of gain-of-function influenza A virus research. Here we present an approach to strengthen the biosafety of gain-of-function influenza experiments. We exploit species-specific endogenous small RNAs to restrict influenza A virus tropism. In particular, we found that the microRNA miR-192 was expressed in primary human respiratory tract epithelial cells as well as in mouse lungs but absent from the ferret respiratory tract. Incorporation of miR-192 target sites into influenza A virus did not prevent influenza replication and transmissibility in ferrets, but did attenuate influenza pathogenicity in mice. This molecular biocontainment approach should be applicable beyond influenza A virus to minimize the risk of experiments involving other pathogenic viruses. Species-specific miRNA expression. Credit: Nature Biotechnology (2013) doi:10.1038/nbt.2666 Study puts troubling traits of H7N9 avian flu virus on display (Phys.org) —It’s a scenario straight out of a sci-fi horror flick. Scientists take a deadly virus that people can only catch from birds and genetically engineer it so we can give it to each other. Unfortunately, the threat of such a highly contagious virus escaping the lab, whether by accident or at the hands of terrorists, could be more than fiction. To ensure that artificial bird flu strains, engineered to be transmissible between mammals, remain confined to laboratories, Benjamin tenOever and his colleagues at Icahn School of Medicine at Mount Sinai have devised a method of molecular biocontainment that prevents the expression of an influenza virus in humans and mice by altering the virus’ genome so it binds to a specific microRNA. Their research appears in Nature Biotechnology. Explore further Journal information: Nature Biotechnology Engineering viruses to make them transmissible among mammals can help scientists learn about how viruses mutate in the wild. The study of gain-of-function mutations is an essential part of disease research. Scientists can use the knowledge obtained from such research to predict how diseases will spread and to develop new vaccines.Recently, scientists discovered that mutations could make the H5N1 and H7N9 strains of avian flu transmissible between ferrets, considered a model for humans in influenza research. Normally, birds can transmit these viruses to humans, but humans can’t transmit them to each other. The mutation that allows ferret-to-ferret transition of H5N1 involves only three changes in the virus’ hemagglutinin protein. The ease with which researchers might create such highly contagious mutations contributes to concerns about safety. Public authorities are worried that a mutation of the H5N1 virus could create a flu pandemic as deadly as that of 1918.To develop a way to limit the spread of the H7N9 strain to particular species, tenOever and his team turned to microRNA, strings of nucleic acid that prevent genes with particular target sequences from expressing themselves. They discovered that one microRNA, miR-192, exists in the respiratory tracts of humans and mice, but not in the respiratory tracts of ferrets.The team inserted the target sequence for miR-192 into the H7N9 genome and exposed mice and ferrets to the virus. The mice, which had miR-192 in their lungs, showed no sign of illness, even when the researchers increased the viral dose 10 times. Ferrets, which had no miR-192, contracted the virus and transmitted it normally. Mice exposed to a form of the virus with a scrambled target sequence or to a control virus died within eight days.TenOever and his team suggest that researchers use their method of containment to restrict transmission to specific species when studying highly contagious viruses, such as Ebola, SARS coronavirus and henipaviruses. 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 Can plants grow on the moon? NASA plans test in 2015 (Phys.org) —Russian cosmonauts on the International Space Station have grown a crop of peas, wheat, and Japanese leafy greens in the ISS greenhouse. The report comes from a researcher with the Russian Academy of Sciences Institute of Biomedical Problems, which is partnered with Utah State University’s Space Dynamics Laboratory. The food was confirmed as safely edible. Their root modules were analyzed to confirm their safety. The team’s success in growing the crops bring hope among space exploration teams that a supply of fresh food might be feasible, in contrast to reliance on food specially packaged to stay edible for long periods. The delivered foods can deliver nutrition but having a supply of fresh food would be desirable to sustain morale and also for another, fundamental, reason. Long-duration deep space missions would require large amounts of food adding to their launch weight. Citation: Peas, other edibles grow in experimental space greenhouse (2014, February 3) retrieved 18 August 2019 from https://phys.org/news/2014-02-peas-edibles-experimental-space-greenhouse.html Credit: NASA © 2014 Phys.org “Launching seeds in place of additional packaged food also reduces the weight of supply payloads which reduces launch costs, an important consideration as the duration of NASA missions gets longer and astronauts require more life support,” said Utah State University’s Crop Physiology Laboratory website. Instead of packaged food for long space missions, crops grown in chambers such as those designed and built at Utah State University’s Space Dynamics Laboratory, the site added, can provide food for astronauts, purify water, and recycle carbon dioxide into oxygen..Next on the cosmonauts’ agenda is to raise rice and bell peppers. Another noteworthy item on the agenda is a grass species, purple false brome, whose genomes have already been sequenced,. The researchers intend to look for possible genetic abnormalities. Their experimental greenhouse aboard the ISS is called Lada. The Russian researcher, Margarita Levinskikh, spoke recently at a conference in Moscow, and her report was carried by the Russian news service RIA Novosti. “The experiments with peas have been very promising,” she said. Last year, NASA said its demo unit was to study the germination of plants in lunar gravity and radiation on the Moon. The self-contained habitat could be a payload on any NASA or commercial lunar lander. “After landing in late 2015,” according to NASA, “water will be added to the seeds in the module and their growth will be monitored for five to ten days and compared to Earth-based controls. Seeds will include Arabidopsis, basil, and turnips.” The experiment is also seen as an important step in knowing more about the use of plants for human life support. More information: cpl.usu.edu/htm/dwarf-crops-for-space-flightwww.nasa.gov/centers/ames/cct/ … nt.html#.Uu8EGPldUu4 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.
Novel beams made of twisted atoms (Phys.org) —For the past few decades, physicists have been studying the phenomenon of “twisted light,” which is light that is twisted like a corkscrew along its axis of travel. Due to the twisting, the light waves at the center of the axis cancel out, resulting in a ring of light with a dark spot in the center. Although it may sound like somewhat of a novelty, twisted light has applications in laser-driven plasma accelerators and plays a role in several astrophysical phenomena such as pulsars, the extremely dense stars that emit light while rotating, somewhat like a lighthouse. While several methods exist for generating twisted light, physicists in a new study have demonstrated for the first time in simulations the possibility of generating relativistic twisted light. Writing in Physical Review Letters, Yin Shi, et al., at the Chinese Academy of Sciences in Shanghai, China, describe this type of light as a spiral-shaped “light fan.” As the physicists show in 3D simulations and analytical modeling, a light fan can be generated by using a relativistic laser pulse. When this laser pulse impinges upon a thin spiral-shaped foil target, a spiral-shaped plasma is created. This is the relativistic light fan, which is characterized by a very strong torque and very high orbital angular momentum. Both the photons and the electrons in the light fan rotate due to the high orbital angular momentum, which can be either clockwise or anticlockwise. The scientists expect that experiments based on these simulations can be realized soon with current technology.”Relativistic twisted light is a twisted light with an intensity that is so large that an electron moves in a velocity close to the speed of light,” coauthor Baifei Shen at the Chinese Academy of Sciences told Phys.org. “Relativistic light has opened new research fields in high-field physics, including laser acceleration and relativistic high-order harmonics, because it has a high energy density. Now, relativistic twisted light has high angular momentum density, which may result in many new physical phenomena.”The light fan’s high angular momentum density may make it very useful for several applications. For example, in laser-driven plasma accelerators, the accelerating force has traditionally been the main point of interest since it is the origin of particle acceleration. However, having a high torque can also be important, although it has not been given much attention so far.”Relativistic twisted light can be used for positron and proton acceleration in the bubble regime, since the driven doughnut wakefield has a transverse focusing force for positively charged particles so that they can be accelerated for a long distance,” Shen said. “The light fan is a rotating structure of large angular velocity, which is due to the conservation of angular momentum. Because the normal light has no angular momentum and the reflected twisted light has angular momentum, the light fan must have opposite angular momentum.”Relativistic twisted light with a strong torque could also be used to mimic some astrophysical environments such as pulsars, leading to a better understanding of these unique and distant stars. More information: Yin Shi, et al. “Light Fan Driven by a Relativistic Laser Pulse.” Physical Review Letters 112, 235001 (2014). DOI: 10.1103/PhysRevLett.112.235001 Citation: Spiral-shaped ‘light fan’ adds new twist to laser-driven plasma accelerators (2014, June 25) retrieved 18 August 2019 from https://phys.org/news/2014-06-spiral-shaped-fan-laser-driven-plasma.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. (a) The normal incident laser pulse has a planar (non-twisted) wave front. (b) After reflecting off of a spiral foil, the light has a helical (twisted) wave front. (c) The foil used in the simulation has eight parts to mimic a spiral phase plate. Credit: Shi, et al. ©2014 American Physical Society Explore further © 2014 Phys.org Journal information: Physical Review Letters
(Phys.org)—A small team of researchers affiliated with the University of Missouri and the University of Nebraska has found that cross-cousin breeding among the Yanomamö people in the Amazon rain forest is beneficial to the parents of young people who wed due to arranged marriages. In their multi-year study, the team describes how they conducted a genealogical study of over 5000 people over the course of 30 years to learn more about Yanomami culture and the impact of cross-cousin marriages. Journal information: Proceedings of the National Academy of Sciences 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: Cross-cousin marriages among the Yanomamo found to benefit grandparents (2017, March 14) retrieved 18 August 2019 from https://phys.org/news/2017-03-cross-cousin-marriages-yanomamo-benefit-grandparents.html Why not marry your cousin? Millions do Explore further Uncontacted indigenous tribe in the brazilian state of Acre. Credit: Gleilson Miranda / Governo do Acre / Wikipedia © 2017 Phys.org More information: Napoleon A. Chagnon et al. Cross-cousin marriage among the Yanomamö shows evidence of parent–offspring conflict and mate competition between brothers, Proceedings of the National Academy of Sciences (2017). DOI: 10.1073/pnas.1618655114AbstractMarriage in many traditional societies often concerns the institutionalized exchange of reproductive partners among groups of kin. Such exchanges most often involve cross-cousins—marriage with the child of a parent’s opposite-sex sibling—but it is unclear who benefits from these exchanges. Here we analyze the fitness consequences of marrying relatives among the Yanomamö from the Amazon. When individuals marry close kin, we find that (i) both husbands and wives have slightly lower fertility; (ii) offspring suffer from inbreeding depression; (iii) parents have more grandchildren; and (iv) siblings, especially brothers, benefit when their opposite-sex siblings marry relatives but not when their same-sex siblings do. Therefore, individuals seem to benefit when their children or opposite-sex siblings marry relatives but suffer costs when they, their parents, or same-sex siblings do. These asymmetric fitness outcomes suggest conflicts between parents and offspring and among siblings over optimal mating strategies. Parental control of marriages is reinforced by cultural norms prescribing cross-cousin marriage. We posit that local mate competition combined with parental control over marriages may escalate conflict between same-sex siblings who compete over mates, while simultaneously forging alliances between opposite-sex siblings. If these relationships are carried forward to subsequent generations, they may drive bilateral cross-cousin marriage rules. This study provides insights into the evolutionary importance of how kinship and reciprocity underlie conflicts over who controls mate choice and the origins of cross-cousin marriage prescriptions. Cross-cousin marriage is where cousins from opposite sex siblings are wedded, generally as part of an arrangement between the parents of the cousins, who are, of course, siblings. As the researchers note, it is more common than parallel cousin marriages in cultures around the globe, though it is not known why. In South America, a group of indigenous people called the Yanomamö live in over 200 villages, which adds up to approximately 35,000 people. Researchers have studied them to learn more about their culture, which includes arranged marriages. The researchers with this effort were interested in cross-cousin or consanguineous marriage, and what benefits it might provide.To learn more about birth rates and patterns, the researchers conducted a long-term genealogical study to find out who, if anyone, benefited from consanguineous marriage. In looking at their charts and family trees, the researchers observed that pairing cross-cousins resulted in lower than average fertility rates for both the male and female in such a union. They also found that doing so resulted in lower fertility rates for their offspring, as well. But, oddly enough, such unions benefited the parents of the cousins because it resulted in more grandchildren. This, the researchers explained, was because the Yanomamö practice prescriptive consanguineous marriage in which males marry the daughters of their parents’ opposite-sex siblings. This cultural exchange of daughters with relatives allows parents to get more wives for their sons, which, in the long run, results in more grandchildren being born.The team suggests their findings might help explain why marriage between cousins persists among many cultures of the world despite it being considered taboo in so many others.
Kolkata: Over five kg gold biscuits valued at Rs 1.72 crore were seized from the city and a smuggler was arrested, the Directorate of Revenue Intelligence said on Sunday. Acting on a tip-off, officers of the DRI Kolkata unit raided a guest house in central Kolkata’s Chowringhee area on Saturday and arrested the smuggler with over 32 gold biscuits with foreign markings.”F. Lalthang Kima of Mizoram’s Aizwal was intercepted and gold biscuits weighing 5.4 kg were seized from two trolley bags he was carrying. He was arrested under the Customs Act,” a DRI release said.The gold was suspected to be smuggled in from Myanmar through the Mizoram border. It was then taken from Aizawl to Kolkata by road.It is the third seizure of foreign-origin gold here in less than a month.The DRI seized close to 430 kg gold and gold jewellery valued at around Rs 100 crore from east and northeast India in the last financial year.
German football legend Franz Beckenbauer on Tuesday labelled Barcelona star Lionel Messi as “God-like” and believes the Spanish team’s hope of success this season rests on his shoulders. The 27-year-old has recovered from a disappointing end to 2014 to inspire his side to a fine run of form domestically and in Europe to leave the club challenging for silverware on three fronts. “Messi is a divine player, he is god-like. The hopes of Barcelona are reliant on Messi,” Beckenbauer told channel Sky 90. Also Read – Khel Ratna for Deepa and Bajrang, Arjuna for JadejaBarcelona lead La Liga by two points ahead of Real Madrid and face Bayern in the semi-finals of the Champions League, while Athletic Bilbao await the Copa del Rey final. Beckenbauer will, of course, hope Messi has a dip in form as his side take on Luis Enrique’s men over two legs, but admitted he is a big admirer of the Argentina international.The European tie will see Bayern Munich coach Pep Guardiola face his former club for the first time since leaving the club in 2012 and Beckenbauer believes his knowledge of the club could be key. “Pep Guardiola knows the ins and outs of Barcelona club. He knows the smallest of details that could put Bayern on their way,” he said.