Super honeycomb shows more potential for carbon nanotubes

first_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: Super honeycomb shows more potential for carbon nanotubes (2007, January 19) retrieved 18 August 2019 from https://phys.org/news/2007-01-super-honeycomb-potential-carbon-nanotubes.html Explore further Scientists Min Wang, Xinming Qiu, and Xiong Zhang from Tsinghua University in Beijing recently investigated the mechanical properties of super honeycomb structures, which are made of periodically repeating carbon nanotube Y junctions that form hexagonal patterns. While straight nanotubes—such as those compiled in bundles or ropes—have renowned strength and elasticity, the honeycomb structure can also transfer these forces to different parts of its structure.“The basic properties of super structures are due to their excellent structures: the hollow structure of arms and perfect honeycomb structure to combine the arms,” Zhang told PhysOrg.com. “Compared with the straight nanotube, the honeycomb structure optimizes the force-transferring.”Although the honeycomb structure may look like a fishnet, the forces that determine the nanostructure’s properties are actually quite different from those of a macroscopic honeycomb or fishnet because of the great scale difference. For example, the scientists indicate that the van der Waals interactions and the recombination of bonds at the atomic level would affect the results when the structure is stretched.“In our article, the shell model is used to analyze the mechanical properties of the super honeycomb structure,” Zhang said. “The method is based on the continuum theory, but the material parameter is obtained from the atomic level.”The scientists found that, when the nano honeycomb was stretched, the structure still maintained high tensile strength. This result arises due to the honeycomb structure’s unusual tendency to become very thin (which is called having a high “Poisson’s ratio”), and gain great flexibility. The scientists found that, the more junctions, the greater strength and ability to “shift” weight to different parts of the structure. “Because the honeycomb structure has the ability to transfer forces, the structure ensures the good distribution of stress and avoids the local stress concentration,” said Zhang. “Even when some tubes are broken from others, the whole structure can still bear the load, which embodies high ductility.”Because the shape of a single Y junction looks like that of a carbon-carbon bond in graphite, the periodically repeating Y pattern has earned the name “super graphite.” Therefore, by rolling up a sheet of honeycomb, you get what the scientists call a “super carbon nanotube.” Using super carbon nanotubes, scientists could build high-strength, large-scale super structures with relatively short tubes that have many junctions as opposed to using longer straight tubes.“Super carbon nanotubes are composed of the lower-order nanotubes by replacing the atomic bonds in the carbon nanotubes, which hold the superior properties of carbon nanotubes and the optimal ductility, which is due to the honeycomb structures,” Zhang explained. The super honeycomb’s ability to transfer forces means that these structures could provide scientists with resources to improve nanoelectronics devices for computers, and also fiber-reinforced composites.“Many nanoelectronic devices based on Y-junction carbon nanotubes have been proposed recently,” said Zhang. “Scientists [Coluci] have discussed the electronic properties of the super structures, and indicated that they have great applications as actuators and as hosts for large biomolecules. Regarding fiber-reinforced composites, just as its name implies, the mechanical properties of materials such as resin and concrete can be improved by adding some fiber components.”Citation: Wang, Min, Qiu, Xinming, and Zhang, Xiong. “Mechanical properties of super honeycomb structures based on carbon nanotubes.” Nanotechnology. 18 (2007) 075711 (6pp).By Lisa Zyga, Copyright 2006 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. On-demand control of terahertz and infrared waves The hexagonal network structure makes these nanotubes look a bit like a honeycomb—or, when stretched a bit, like a hammock or fish net. In fact, the stretchiness of these 20-nm-long carbon nanotubes enables them to do what straight nanotubes find difficult: namely, transfer tensile forces and possess high ductility, or malleability. When one tube in the honeycomb structure is broken, the surrounding arms can easily carry the load due to the structure’s ability to transfer forces. The colors show the von Mises stress distribution, with dark blue as lowest stress and MX referring to the place with maximum stress. Image credit: Xiong Zhang, et al.last_img read more

Dark Energy And The Inverse Square Law

first_img Citation: Dark Energy And The Inverse Square Law (2007, January 25) retrieved 18 August 2019 from https://phys.org/news/2007-01-dark-energy-inverse-square-law.html “Newton’s inverse-square law has been around for a while,” Daniel Kapner tells PhysOrg.com. “But, by testing this law, we’re looking for new physics.” The new physics Kapner and his colleagues are looking for in their recent Physical Review Letters submission deals with dark energy. “Dark energy is an unknown driving force behind the acceleration of the universe, and we’re measuring the inverse-square law below the dark-energy length scale to look for a possible new gravitational phenomenon.”Kapner and his colleagues are associated with the Center for Experimental Nuclear Physics and Astrophysics at the University of Washington in Seattle. Their Letter, “Tests of the Gravitational Inverse-Square Law below the Dark-Energy Length Scale,” addresses questions of dark energy gravity possibilities. “As the universe expands, gravity should be slowing down that expansion,” explains Kapner. “But that’s not what is happening. Astrophysical measurements show that the expansion is speeding up. The unknown mechanism behind this accelerated expansion is termed Dark Energy.” Kapner and his colleagues use a sensitive device called a torsion balance to test the inverse-square law, attempting to shed some light on dark energy. “This is one step more complicated than the old mass on the end of a spring,” Kapner says, referring to the classic physics class demonstration of measuring a force by the distance a spring stretches. While the earth’s gravity pulls straight down, a sideways force can induce a very small twist of the balance. “This is done a vacuum chamber,” explains Kapner, “so there is no friction. This is essentially the best you can do with a direct measurement. If standard physics has new particles or exchange forces which act at this length scale, this apparatus would be sensitive to it.” The group’s torsion balance can measure gravity-strength forces down to distances of 55 microns.And the results regarding the dark-energy length scale? “There are no deviations from the inverse-square law,” Kapner insists. “We see it behaves just as Newton predicted.” The test, he says, establishes that there is nothing new at the dark-energy length scale. So the continuing acceleration of the universe remains a mystery.But the test used by Kapner and his colleagues is not limited to questions of dark energy. The torsion balance measurements can be used to constrain other models that suggest new exchange forces and particles. “We’ve used this to test other models, such as large extra dimensions in string theory,” he says. “And we could test any other models which predict deviations from the inverse-square law.”Kapner says that the next version of the project is being built now. “We can go to even smaller lengths, and get results that are 100 times better.” Kapner thinks that the current test pretty well ruled out that dark energy holds nothing new regarding short-distance gravity, but another test would make the team’s assertion stronger. “We want to keep refining this technique as far as technology will allow.”After all, Kapner points out, “Even though the obvious answer wasn’t there, this technique still holds promise for discovering something new.”By Miranda Marquit, Copyright 2007 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.center_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

Robot Suit May Help You Achieve a Perfect Golf Swing

first_imgA robotic feedback suit: markers on the right arm indicate the joints that are regulated by the system. Credit: Lieberman and Breazeal. ©2007 IEEE. MIT researchers Jeff Lieberman and Cynthia Breazeal have published the results of the study in a recent issue of IEEE Transactions on Robotics. The study presents a proof-of-concept wearable robotic system that provides real-time tactile feedback over every joint simultaneously. “Oddly enough, the idea for the robot suit initially came from a dream,” Lieberman told PhysOrg.com. “The dream involved people who weren’t physically able to express themselves, but who were mentally normal, who used a machine that aided them to get their inner feelings out. This ranged from people with muscular difficulties to even toddlers and ‘untrained’ people who do not know how to wield a paintbrush. Upon waking and thinking about that idea for about an hour, the idea for this project was born, and I started doing research that day; the overall project was about six months for software and hardware development.”In experiments with arm motions, the researchers found that the suit increased students’ learning rates by up to 23%, and reduced errors by up to 27%, as well as enabling students to learn movements “more deeply” by affecting their subconscious learning of motor skills. The latter can be especially important for patients with neurological injuries who have lost the ability to form new long-term memories, but can still build new motor skills.The suit works by optically tracking body markers for the teacher’s movement (or a pre-recorded ideal movement) and the student’s movement with a Vicon motion capture system, which has millimeter accuracy. The tracking data is fed to software that compares the teacher’s and student’s movements, and generates feedback signals to the suit. “The most challenging part was the human motion tracking system, which needs to function extremely quickly [about 100 hz] and be extremely accurate [about 1mm] to be able to adequately represent complex human motions,” Lieberman explained. “The system we use is a very expensive one for very high-tech applications, and for this to be successful in the real world it has to be much less expensive, and very robust. Tracking systems are typically optical [needing a setup in the room] or exoskeleton-style [wearable] which results in high expense and high weight, respectively. We’d like to solve both those at the same time and are working on new possibilities, although it is not the main focus of the research.” Small actuators against the skin vibrate in proportion to the amount of positional error of the student’s joints, giving the sensation of a vibrating “force field” around the correct motion. The suit can also correct for rotational errors of joints by sequentially vibrating individual actuators placed around joints clockwise or counterclockwise, giving the sensation that a rotating signal is urging the joint to rotate. Because everyone has different physical proportions, the system must first spend 10 minutes calibrating a new user’s limb lengths and joint locations, and then match them to the teacher’s proportions. Once a teacher’s motions are tracked, they can be recorded, repeated, and played at different speeds.As the researchers explain, the system has the potential to teach a student the precise motions of a teacher in place of the teacher. The system could therefore work well for teachers who are highly skilled, but are not good at teaching, by physically guiding a student who can simultaneously watch the teacher or a pre-recorded motion for visual feedback. However, visual feedback may not even be necessary with the wearable feedback suit, giving it the potential to be used as a training device for blind individuals.“The biggest initial market is in a sport such as golf, which already spends millions annually on video analysis machines, which tell the student exactly what they need to change,” Lieberman said. “But it tells them after they’re done, and decades of motor learning research tells us that students will learn much more quickly if the feedback is given immediately with no delay. Imagine how easy improving your swim stroke would be if you didn’t need to lift your head out of the water to improve it; after about 100 strokes, you’d be mimicking your teacher almost exactly.”He also explained that the health industry represents an equally, if not more exciting, opportunity. People with neurological trauma might use the suit for remapping their brains, and people with back pain could train their muscles with correct posture.“We are developing a new system using this technology that will monitor your posture and give you vibrotactile cues to keep yourself sitting properly,” Lieberman said. “Typically people only realize their posture is bad once pain starts, so this would give immediate feedback to prevent any pain, and retrain those who have already developed back pain. We should be running tests on this new device early next year. You can imagine having one suit, and 10 people each wearing it one week out of 10, to retrain their posture; the retraining of muscles should have a long-lasting effect, greatly helping those with back pain.”Before some of the complex motions— like a golf swing—are tested, however, the researchers say improvements are needed on the robot suit. These include creating a full-body suit with more than 100 actuators, defining ideal marker placement, investigating the human ability to respond to large amounts of feedback, and finding a less expensive and more mobile tracking system.“With the golf swing, the difficulty lies not only in the fact that you need to monitor many more joints, but also that the mapping from teacher to student is much harder to clearly define,” Lieberman explained. “In our tests, the mapping explicitly told the subject to try to copy the angles the teacher was making. In golf, it is more important that the end of the club contact the ball, and copying normal angles from someone taller than you will result in the club going into the ground, so it’s very difficult to map that.”Related information: robotic.media.mit.edu and bea.st. Citation: Lieberman, Jeff and Breazeal, Cynthia. “TIKL: Development of a Wearable Vibrotactile Feedback Suit for Improved Human Motor Learning.” IEEE Transactions on Robotics, Vol. 23, No. 5, October 2007.Copyright 2007 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. Researchers have developed a vibrotactile feedback suit to help individuals learn new motor skills more quickly and accurately than by mimicking human teachers alone. Besides golf, dance and sports training, the suit may also be useful for individuals undergoing motor rehabilitation after neurological damage, as well as for posture improvement.center_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: Robot Suit May Help You Achieve a Perfect Golf Swing (2007, October 31) retrieved 18 August 2019 from https://phys.org/news/2007-10-robot-golf.htmllast_img read more

New evidence backs up claim of dinosaur soft tissue find

first_img Explore further Citation: New evidence backs up claim of dinosaur soft tissue find (2011, June 15) retrieved 18 August 2019 from https://phys.org/news/2011-06-evidence-dinosaur-soft-tissue.html (PhysOrg.com) — In a new study, biochemist James San Antonio and colleagues offer evidence to support the claims by Mary Higby Schweitzer back in 2005, that she and her colleagues had unearthed a soft tissue specimen that belonged to a Tyrannosaurus rex. Roundly criticized by many in the science community, the specimen, discovered inside a femur fragment, has yet to be proven to be anything else. Now, in a paper published on PLoS ONE, San Antonio and his colleagues (including Mary Schweitzer) claim they’ve found a plausible explanation for the survival of soft dinosaur material after some 68 million years. The team focused on bits of collagen found in the remains, which are a group of proteins found in the flesh and bones of animals; it grows in a triple helix, which when it winds together, is known as a microfibril. When thousands of microfibril wind together, as they often do, they are known as microfibrils. After carefully studying 11 fragments of collagen recovered from the T. rex bone and then comparing them to similar fragments in modern rat and human collagen, the team discovered that the found fragments all came from the same innermost part of the fibrils that make up microfibrils. San Antononio likens them to tiny fibers that sit at the very innermost part of a very thick strong rope.In their paper, the research team suggests that because they were so tightly wound, the microfibrils could have survived over millions of years. They also note that the specimens also contained very few amino acids, which are very susceptible to decay.To back up her claims, or to quiet the naysayers, Schweitzer points out that if the specimens found were actually contaminants from other more recent organisms, as some have claimed, there should have been more randomness to the collagen, instead of the strict uniformity that was found. She also notes that two other labs have corroborated her results.The unfortunate side story to all the research done so far though, including these latest findings, is that thus far there is no way to definitively prove whether the soft tissue found inside that T. rex bone was in fact a remnant from its original owner, or something that came after. Thus, claims from both those supporting the idea that dinosaur tissue could have survived for millions of years, and those that think it’s nonsense, are likely to continue. © 2010 PhysOrg.com More information: San Antonio JD, Schweitzer MH, Jensen ST, Kalluri R, Buckley M, et al. (2011) Dinosaur Peptides Suggest Mechanisms of Protein Survival. PLoS ONE 6(6): e20381. doi:10.1371/journal.pone.0020381AbstractEleven collagen peptide sequences recovered from chemical extracts of dinosaur bones were mapped onto molecular models of the vertebrate collagen fibril derived from extant taxa. The dinosaur peptides localized to fibril regions protected by the close packing of collagen molecules, and contained few acidic amino acids. Four peptides mapped to collagen regions crucial for cell-collagen interactions and tissue development. Dinosaur peptides were not represented in more exposed parts of the collagen fibril or regions mediating intermolecular cross-linking. Thus functionally significant regions of collagen fibrils that are physically shielded within the fibril may be preferentially preserved in fossils. These results show empirically that structure-function relationships at the molecular level could contribute to selective preservation in fossilized vertebrate remains across geological time, suggest a ‘preservation motif’, and bolster current concepts linking collagen structure to biological function. This non-random distribution supports the hypothesis that the peptides are produced by the extinct organisms and suggests a chemical mechanism for survival. Tyrannosaurus rex femur (MOR 1125) from which demineralized matrix (insets; bars, 20 µm) and peptides were obtained. Image: PLoS ONE 6(6): e20381. doi:10.1371/journal.pone.0020381 Proteins, Soft Tissue from 80 Million-Year-Old Hadrosaur Add Weight to Theory that Molecules Preserve Over Time 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

Is cannibalism in polar bears on the rise

first_img © 2011 PhysOrg.com At the American Geophysical Union (AGU) Fall Meeting, Jenny Ross, an environmental photojournalist, presented a series of photographs of an adult male polar bear (Ursus maritimus) carrying the carcass of a young cub. Ross said the bear’s behavior suggested it considered the cub to be food, and it carried the corpse in its jaws to another floe to get away from the researchers. When it was some distance away it then devoured the cub. Dr Ian Stirling of Environment Canada, who co-wrote the paper published in the journal Arctic, said cannibalism among polar bears has been witnessed before, but he said the rate of cannibalism may be increasing as the sea ice now melts earlier in the year. The primary food source for polar bears is seals, which they normally hunt from ice floes. The ice floes melt during summer and in some places the ice disappears altogether, making hunting for seals more difficult. Ross said the bears are forced to seek out other foods such as sea birds and their eggs, and human foods and waste, but these are not enough to sustain them. Ross said cannibalism has always occurred “to some extent” and bear cubs were probably easy prey, particularly for a large male bear. She said the cannibalistic behavior may rise as hunting becomes more difficult with the climate continuing to warm in the Arctic. She also said there were increasing numbers of observations of cannibalism, especially on land among bears that had no food for extended periods.The observation of cannibalism in polar bears is not new. A 1985 paper in Arctic listed incidents of cannibalism dating back to 1896, while a 1999 paper by Derocher and Wiig in Arctic concluded that cannibalism in polar bears “may be more common in Svalbard… because the population is close to carrying capacity or because geographic features reduce patial segregation of age and sex classes.” Hunting of polar bears in the Svalbard-Barents sea area ceased in 1956 in Russia and 1973 in Norway, which Derocher and Wiig said allowed the population to increase and reach carrying capacity.Cannibalism has also been observed among captive polar bear populations in zoos, such as an incident in 2008 in Nuremburg zoo, in which a mother bear killed and ate her two cubs, despite being well fed. According to the president of the Kivalliq Inuit Association, Jose Kusugak, the behavior is “quite normal.” Explore further Citation: Is cannibalism in polar bears on the rise? (2011, December 9) retrieved 18 August 2019 from https://phys.org/news/2011-12-cannibalism-polar.html Polar bears ‘spotted swimming with cubs on back’ (PhysOrg.com) — A series of photographs of cannibalism in polar bears have been released, and the researchers who witnessed the act think the rate of cannibalism may be increasing. They observed three instances of adult male polar bears killing and eating young cubs during summer and autumn in the Svalbard archipelago in Norway and made a series of photographs of one episode. 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

CyPhy Works takes wraps off longendurance UAVs w video

first_img(Phys.org)—Massachusetts-based CyPhy Works has unveiled two types of Unmanned Aerial Vehicles (UAVs) that it has designed for use by military and emergency personnel. Its EASE UAV (short for Extreme Access System for Entry) is designed for tight-squeeze situations. The device is only one foot in diameter and stands 16 inches tall. While, for example, military or emergency personnel stand at a safe distance, this indoor flying UAV can hover, using machine-vision stabilization, into a building while relaying high-definition video footage via integrated cameras to an operator outside. Able to fly into tight spaces, the UAV navigates easily through both doors and windows. It also has a thermal imaging device. The company has also unveiled a larger UAV, which is a quadrotor air vehicle called PARC (short for Persistent Aerial Reconnaissance and Communications), able to reach higher altitudes than EASE. This is designed to fly vertically and to stay in hovering mode for long durations. It can fly up to 1,000 feet above ground. The PARC vehicle is powered from the ground; the flight duration is not limited by battery life. It can stay aloft on a single ground station battery for twelve hours. The PARC system can accept power input from a variety of ac and dc sources. The company has made much of the microfilament advantage. As long as the wire stays intact, signals cannot be interrupted or interfered with. High quality, high definition video can be streamed through them. The microfilament enables the use of sensors that are superior, said the company, with high data throughput. The microfilament enables video that is unbroken; commands and receiving sensor data will be reliable; GPS denial is not an issue. Helen Greiner, the company CEO, summed it up in saying “With the filament, basically you get high-definition video images all the time, and then it has the added advantages in that it can’t be jammed, it can’t be spoofed, it can’t be intercepted.” 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 company noted that EASE carries no GPS; the vehicle is stationed at any particular location via s thin wire filament that trails behind, providing the power to remain skulking about. Just please do not call the filament a “tether.” According to the company. “We differentiate microfilament from traditional tethered systems. The word tether means a rope or chain used to restrict movement, and that is the exact opposite of what microfilament does for its users. Microfilament enables movement, it doesn’t restrict it.” Explore furthercenter_img More information: cyphyworks.com/ Nimbus Lab sends up quadrotors for wireless charging (w/ Video) Citation: CyPhy Works takes wraps off long-endurance UAVs (w/ video) (2012, December 6) retrieved 18 August 2019 from https://phys.org/news/2012-12-cyphy-long-endurance-uavs-video.html © 2012 Phys.orglast_img read more

Study shows global forest loss over past 35 years has been more

first_imgA team of researchers from the University of Maryland, the State University of New York and NASA’s Goddard Space Flight Center has found that new global tree growth over the past 35 years has more than offset global tree cover losses. In their paper published in the journal Nature, the group describes using satellite data to track forest growth and loss over the past 35 years and what they found by doing so. There has been a growing consensus in recent years that because humans cut down so many trees (most particularly in the rainforests) that global tree cover is shrinking. In this new effort, the researchers have found that not to be the case. They contend that global tree cover is actually increasing.To track global tree cover changes, the researchers studied data from advanced very high-resolution radiometers aboard a series of 16 weather satellites covering the years 1982 to 2016. By comparing daily readings, the researchers were able to see small changes occurring regularly over a relatively long period of time—which added up to large changes. Over the entire span, the researchers found that new tree cover had offset tree cover loss by approximately 2.24 million square kilometers—which they note is approximately the size of Texas and Alaska combined.The researchers report that most of the new tree cover occurred in places that had previously been barren, such as in deserts, tundra areas, on mountains, in cities and in other non-vegetated land. They further report that much of the new growth came about due to efforts by humans (such as reforestation efforts in China and parts of Africa) and because of global warming—warmer temperatures have raised timberlines in some mountainous regions, and allowed forests to creep into tundra areas. Other areas of new tree growth resulted from large farm abandonments in places like Russia and the U.S. The researchers report that their calculations showed that human activities have directly caused approximately 60 percent of new global tree growth. They suggest their technique for monitoring tree cover could be used to predict tree cover changes in the future due to global warming. a, Mean annual estimates. b, Long-term change estimates. Both mean and change estimates are expressed as per cent of pixel area at 0.05° × 0.05° spatial resolution. Pixels showing a statistically significant trend (n = 35, two-sided Mann–Kendall test, P < 0.05) in either TC, SV or BG are depicted on the change map. Circled numbers in the colour legend denote dominant change directions: 1, TC gain with SV loss; 2, BG gain with SV loss; 3, TC gain with BG loss; 4, BG gain with TC loss; 5, SV gain with BG loss; and 6, SV gain with TC loss. Credit: Nature (2018). DOI: 10.1038/s41586-018-0411-9 Journal information: Nature © 2018 Phys.org Cities and communities in the US losing 36 million trees a yearcenter_img Citation: Study shows global forest loss over past 35 years has been more than offset by new forest growth (2018, August 9) retrieved 18 August 2019 from https://phys.org/news/2018-08-global-forest-loss-years-offset.html Explore further More information: Xiao-Peng Song et al. Global land change from 1982 to 2016, Nature (2018). DOI: 10.1038/s41586-018-0411-9AbstractLand change is a cause and consequence of global environmental change. Changes in land use and land cover considerably alter the Earth’s energy balance and biogeochemical cycles, which contributes to climate change and—in turn—affects land surface properties and the provision of ecosystem services. However, quantification of global land change is lacking. Here we analyse 35 years’ worth of satellite data and provide a comprehensive record of global land-change dynamics during the period 1982–2016. We show that—contrary to the prevailing view that forest area has declined globally—tree cover has increased by 2.24 million km2 (+7.1% relative to the 1982 level). This overall net gain is the result of a net loss in the tropics being outweighed by a net gain in the extratropics. Global bare ground cover has decreased by 1.16 million km2 (−3.1%), most notably in agricultural regions in Asia. Of all land changes, 60% are associated with direct human activities and 40% with indirect drivers such as climate change. Land-use change exhibits regional dominance, including tropical deforestation and agricultural expansion, temperate reforestation or afforestation, cropland intensification and urbanization. Consistently across all climate domains, montane systems have gained tree cover and many arid and semi-arid ecosystems have lost vegetation cover. The mapped land changes and the driver attributions reflect a human-dominated Earth system. The dataset we developed may be used to improve the modelling of land-use changes, biogeochemical cycles and vegetation–climate interactions to advance our understanding of global environmental change. 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

Researchers discover genomewide variations in gene expression between male and female mammals

first_imgA team of researchers affiliated with several institutions in the U.S. has discovered genome-wide variations in gene expression between male and female mammals. In their paper published in the journal Science, the group describes their RNA sequencing studies in several types of mammals and what they found. Play Researchers find an evolutionarily preserved signature in the primate brain 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. Physiological differences between mammalian genders are quite often easy to spot—in addition to organs involved in reproduction, there are skeletal and facial hair differences, as well as height differences. Prior research and anecdotal evidence has also suggested there may be some differences in the way the brain works. But what about variations in gene expression? The researchers in this new effort report that very little research has been done in this area, which is a problem—recent studies have shown that there are many gender-based health issues. Women are more likely to suffer from autoimmune diseases, for example. And men are more likely to develop cardiovascular diseases. To understand why such differences exist, medical scientists need to better understand gender-based variations in the genome. To learn more about gender-based gene expression, the researchers sequenced the RNA of both genders of four non-human mammals: rats, mice, macaques and dogs. As part of their efforts, they tested different tissues in each of the animals to ensure that each germ layer was represented. They also sequenced tissue from all of the most prominent organs. They then compared what they found to similar data collected from human subjects stored in the Genotype Tissue Expression Consortium database.The researchers found examples of hundreds of conserved gender-biased gene expressions in each tissue. As just one example, they found that 12 percent of the gender differences related to average height in humans could be attributed to conserved gender-biased gene expression. They note that such findings are significant because they prove that gender biases in gene expression can lead directly to differences in traits.The researchers also found evidence that suggested such gender-biased gene expressions came about relatively recently, evolutionarily speaking. They suggest this finding indicates that researchers need to pay particular attention to such differences when using non-human models to study gender-based differences in humans. 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 Credit: CC0 Public Domaincenter_img © 2019 Science X Network Citation: Researchers discover genome-wide variations in gene expression between male and female mammals (2019, July 19) retrieved 18 August 2019 from https://phys.org/news/2019-07-genome-wide-variations-gene-male-female.html More information: Sahin Naqvi et al. Conservation, acquisition, and functional impact of sex-biased gene expression in mammals, Science (2019). DOI: 10.1126/science.aaw7317 Journal information: Science Explore furtherlast_img read more

Always Waiting for the Other Shoe to Drop Heres How to Quit

first_imgBut taking yourself out of the moment to dread what might happen next won’t prepare you for disaster. Indeed, research has shown that it’s the ability to experience positive emotions that improves our ability to cope with distress. Even better, research from Sonja Lyubomirsky, a psychologist at the University of California, Riverside, finds that experiencing positive emotions doesn’t set you up for disappointment, but increases your likelihood of achieving your work, health and relationship aspirations. Read the whole story: The New York Times Ever felt as if the joy of a big win was contaminated with the stress of imagining when the pendulum would swing the other way and something awful would happen to balance it out? If so, you’re not alone: Often, when driven people care about something and finally experience whatever they’ve been hoping to achieve — whether it’s a new relationship, a health goal, a promotion or something else altogether — they’re unable to entirely savor the good times. They may, in fact, do the exact opposite: endlessly worry about when their peak might plummet.last_img read more

Vegan delight

first_imgVegetarians often complain for the lack of option in the Capital, but complain no more! With special focus on perfection, Mr Banan, the man behind success and popular chains like Sagar Ratna and Swagath, has brought the same passion to its vegetarian venture Shraman at the Ashok.With its many cultural influences, it’s a place that offers a varied selection of cuisines to satisfy your palate. Signature dishes like Saundhi Paneer Tikka, Shraman 56 Bhog, Paneer Lazeez, Dal Shraman, Gatta Curry, Jodh Puri Mirchi Paneer, Vegetable Lohla Puri, Sabzi Balluchi and Shraman Punch will leave one craving for more. A visit promises to be a feast not only for the taste buds but also for the eyes.last_img read more