How to Shrink a Carbon Nanotube

first_imgA depiction of the gradual reduction of the diameter of a carbon nanotube via the process created by Yuzvinsky et al. (Image courtesy Tom Yuzvinsky) A research group has devised a way to control the diameter of a carbon nanotube – down to essentially zero nanometers. This useful new ability, designed by scientists from the University of California at Berkeley and Lawrence Berkeley National Laboratory, may help carbon nanotubes become more easily incorporated into new technologies. “One of the biggest hurdles in working with carbon nanotubes has been lack of control over their size,” said UC Berkeley physicist Tom Yuzvinsky, the study’s lead author, to PhysOrg.com. “Now that we can precisely set the diameter of carbon nanotubes, we can tailor individual nanoscale devices to meet our needs.”The exceptional electrical and physical properties of carbon nanotubes – for example, they conduct very well and are extremely strong – have led them to become the basis of many nanoscale devices, such as sensors and transistors. But since these properties depend on the size of the nanotubes and methods to precisely control their size have been unreliable, nanotubes have not been as thoroughly incorporated into new technologies as many scientists would like.Yuzvinsky and his colleagues have taken a significant step toward changing this.They began with a multi-walled carbon nanotube (which resembles a few single nanotubes nested together); theirs had four walls. They applied a carefully selected voltage to the nanotube, which caused the outer two walls to break down electrically and fall away. The already-slimmer nanotube was next bombarded with a high-energy electron beam that knocked carbon atoms out of the nanotube, creating vacancies and other defects in its atomic structure. Simultaneously, the group ran a current through the nanotube. This heated it to the point where it could heal its vacancies and defects by spontaneously reforming into a narrower, nearly defect-free nanotube.Repeating this process shrank the nanotube gradually and controllably in a matter of minutes. As the diameter dwindled, Yuzvinsky and his collaborators were careful to adjust the current through nanotube to account for its increasing electrical resistance. This yielded a surprising and important secondary result of their work: that the conductance of a multi-walled carbon nanotube is directly proportional to its diameter. This clears up many conflicting studies of electrical conduction in nanotubes.The researchers followed the changes as they occurred using a transmission electron microscope, which produced detailed images of the nanotube. Eventually, they could see that the nanotube became so narrow (less than one nanometer) that the inner wall broke, leaving two nanotube fragments connected by an unstable bridge of carbon atoms that soon failed as well.Citation: T.D. Yuzvinsky, W. Mickelson, S. Aloni, G.E. Begtrup, A. Kis, and A. Zettl, “Shrinking a Carbon Nanotube.” Nano Lett. (2006) DOI: 10.1021/nl061671jBy Laura Mgrdichian, Copyright 2006 PhysOrg.com Explore further Citation: How to Shrink a Carbon Nanotube (2006, November 30) retrieved 18 August 2019 from https://phys.org/news/2006-11-carbon-nanotube.html Breakthrough gives artificial muscles superhuman strength 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

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Bats may use magnetic polarity for navigation

first_img Lunar and solar eclipses make animals do strange things The finding may not only explain bats’ long-distance navigation and foraging abilities, but also may provide insight on when and how magnetic field detection evolved in mammals and non-mammals. So explain the researchers, Yinan Wang, Yongxin Pan, Stuart Parsons, Michael Walker, and Shuyi Zhang, who are from the Chinese Academy of Sciences in Beijing, East China Normal University in Shanghai, and the University of Auckland in New Zealand.“The fact that the only two flying vertebrates, bats and birds, do not derive the same information about direction from the Earth’s magnetic field despite apparently similar navigational requirements has very important implications for the evolution of the magnetic sense in vertebrates,” Parsons told PhysOrg.com. “I think it is likely that other mammals possess the ability to detect the field, i.e. have the physiological and anatomical specialization necessary. However, this does not mean that they actually use this information.”In their experiment, the scientists studied the reactions of Nyctalus plancyi bats in an experimental chamber when exposed to an altered magnetic field. The team recorded the hanging positions of the bats with an infrared camera, and then used Helmholtz coils to generate a magnetic field that aligned with the local geomagnetic axis at Beijing, where the experiment took place, with twice the intensity of Earth’s magnetic field. After exposing the bats to the induced magnetic field for several days, the researchers then altered the horizontal and vertical components of the field, both simultaneously and independently. As the group explained, altering the vertical field affects the magnetic inclination, while altering the horizontal field affects the magnetic polarity. Many birds and other non-mammals are known to react to inclination, meaning that they can use information about the different angles that the Earth’s magnetic field is tilted toward the Earth to determine relative latitude. For example, inclination is 90 degrees at the poles (perpendicular to the Earth) and 0 degrees at the equator (parallel to the Earth)—similar to the pattern that lead filings make when placed around a bar magnet. Some birds, like the Arctic Tern, use inclination to annually navigate all the way from the North Pole to the South Pole and back. However, unlike birds, the bats did not react to a change in the vertical field, implying that they do not use inclination when roosting or navigating. On the other hand, when the researchers altered the horizontal field, the bats changed their hanging positions, switching from the northern to the southern end of their basket. The scientists predict that magnetic polarity may help the bats in thermoregulation, since they choose warmer sites to control lactation and development, as well as to minimize the energy used during torpor (hibernation). If they used magnetic polarity in roosting, the scientists suggest, the bats are also likely use polarity to navigate, such as when Nyctalus noctula migrate up to 1600 km between seasons.How do they do it? The scientists explain that animals which use magnetism to navigate are generally thought to use light exposure, magnetite receptors, or both. For example, birds may use a light-dependent mechanism in the right eye for directional information, and a magnetite receptor in the upper beak for detecting variations in magnetic intensity. Most likely, bats use some kind of magnetite receptor. Why the two animals developed sensitivities to different magnetic information is still a question, however. Parsons speculated that an inclination compass may offer more tolerance for birds crossing the equator. Also, when the Earth’s magnetic field occasionally reverses, the birds will not be confused.“It has been suggested that the ability of birds to detect the inclination of the Earth’s magnetic field means that reversal of the polarity of the Earth’s magnetic field will not affect the ability of birds, particularly migratory birds, to set compass courses because there will be a magnetic pole in each hemisphere and the birds will know the direction toward the near pole and the equator as a consequence,” added Walker. “In contrast, the fact that mammals appear to respond to magnetic polarity suggests they will know where magnetic north is but not which hemisphere they are in and may get misled following a reversal of the polarity of the Earth’s magnetic field.”Another significant point from the experiments is that polarity alone is sufficient to navigate long distances. The research also suggests that inclination and polarity detection may have evolved independently in birds and mammals, which means the ability would have emerged after the evolutionary transition from land to air—and would also explain why humans are quite poor at navigating in the absence of a map and a GPS.Citation: Wang, Yinan, Pan, Yongxin, Parsons, Stuart, Walker, Michael, and Zhang, Shuyi. “Bats respond to polarity of a magnetic field.” Proceedings of the Royal Society B. doi:10.1098/rspb.2007.0904. 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 found that bats have a special ability to detect the polarity of a magnetic field, meaning that the creatures can tell the difference between north and south. The only other animal known to have this ability is the mole rat, while birds, fish, amphibians, and all other non-mammals possess a different version of the magnetic compass. Citation: Bats may use magnetic polarity for navigation (2007, September 20) retrieved 18 August 2019 from https://phys.org/news/2007-09-magnetic-polarity.htmlcenter_img Experimental setup showing the bats’ roosting chamber, with the bats gathered at one end of the basket in response to the polarity of the induced magnetic field. Credit: Yinan Wang, et al. Explore further 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

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Scientists develop vaccine against cattle disease

first_img Journal information: Proceedings of the National Academy of Sciences Viral life cycle of malignant catarrhal fever explained Citation: Scientists develop vaccine against cattle disease (2013, April 30) retrieved 18 August 2019 from https://phys.org/news/2013-04-scientists-vaccine-cattle-disease.html Explore further 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. (Phys.org) —Malignant catarrhal fever (MCF) is a disease that is almost always fatal in cattle. Cows contract MCF after coming into contact with wildebeest carrying a form of herpes virus known as alcelaphine herpesvirus 1 (AlHV-1). In a paper published in the Proceedings of the National Academy of Sciences, Benjamin Dewals of the Faculty of Veterinary Medicine at the University of Liège in Belgium and his team report that they have discovered the gene that enables AlHV-1 infection to progress to MCF, and they have developed a vaccine against the disease. More information: An essential role for γ-herpesvirus latency-associated nuclear antigen homolog in an acute lymphoproliferative disease of cattle, PNAS, Published online before print April 29, 2013, doi: 10.1073/pnas.1216531110 AbstractWildebeests carry asymptomatically alcelaphine herpesvirus 1 (AlHV-1), a γ-herpesvirus inducing malignant catarrhal fever (MCF) to several ruminant species (including cattle). This acute and lethal lymphoproliferative disease occurs after a prolonged asymptomatic incubation period after transmission. Our recent findings with the rabbit model indicated that AlHV-1 infection is not productive during MCF. Here, we investigated whether latency establishment could explain this apparent absence of productive infection and sought to determine its role in MCF pathogenesis. First, whole-genome cellular and viral gene expression analyses were performed in lymph nodes of MCF-developing calves. Whereas a severe disruption in cellular genes was observed, only 10% of the entire AlHV-1 genome was expressed, contrasting with the 45% observed during productive infection in vitro. In vivo, the expressed viral genes included the latency-associated nuclear antigen homolog ORF73 but none of the regions known to be essential for productive infection. Next, genomic conformation analyses revealed that AlHV-1 was essentially episomal, further suggesting that MCF might be the consequence of a latent infection rather than abortive lytic infection. This hypothesis was further supported by the high frequencies of infected CD8+ T cells during MCF using immunodetection of ORF73 protein and single-cell RT-PCR approaches. Finally, the role of latency-associated ORF73 was addressed. A lack of ORF73 did not impair initial virus replication in vivo, but it rendered AlHV-1 unable to induce MCF and persist in vivo and conferred protection against a lethal challenge with a WT virus. Together, these findings suggest that a latent infection is essential for MCF induction. Every year, 1.3 million wildebeest migrate across eastern Africa. Almost all of them carry the AlHV-1 virus, which has no effect on them. When wildebeest enter grazing areas, young wildebeest spread the virus through their nasal secretions, infecting cattle. Infected cattle develop MCF, which causes immune cell production to spin out of control, leading to death within a few weeks. MCF is devastating to the Masai people of the region, whose lives depend on livestock farming. Wildebeest in zoos can also spread AlHV-1, causing MCF, for which there is no cure, in some endangered ruminant species. Herpes viruses such as AlHV-1 can replicate in cells that they infect, or they can remain dormant, in a latent state. To determine which method AlHV-1 uses, Dewals and his team infected calves with the virus. All of the calves developed MCF. The researchers then analyzed cellular and viral RNA from the calves’ lymph nodes. They discovered that the virus took the form of episomes, ringed structures that indicate latency, and that infected T-cells contained high levels of the gene ORF73, which codes for a protein needed to maintain latency. Dewals and his colleagues then created a recombinant form of AlHV-1 that lacked ORF73. While this version of the virus was still able to replicate, rabbits infected with it never developed MCF. When the researchers infected these rabbits with normal AlHV-1, the rabbits did not develop the disease, indicating that the knockout virus could be act as a vaccine.According to the team, the virus’ latency creates an evolutionary advantage for both itself and the wildebeest. Because AlHV-1 can persist in wildebeest without causing it any harm, it spreads easily through the entire population, gaining a huge number of hosts. At the same time, the virus kills other species that compete with wildebeest for resources. Transmission of AlHV-1 is highest during wildebeest calving season. Animals weakened by MCF would attract the attention of predators that would otherwise prey on wildebeest calves. © 2013 Phys.orglast_img read more

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Scientists announce development of wheat strain that produces 30 greater yields

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. More information: via BBC Developed by the Cambridge-based National Institute of Agricultural Botany, the new strain came about as researchers mixed “ancient” seeds (from seed banks) with those from the modern era. Importantly, the process did not involve genetic modification as such grains have been banned in many countries. Instead, the researchers cross-bred samples and used embryo transfer techniques to bring about a wholly new strain of wheat. Its developers say that thus far, they’ve seen yield increase of up to 30 percent. They add that the new strain is hardier as well—able to stand up to pests and drought better than conventional wheat varieties.The news comes as welcome relief to people in Britain as bad weather has led to less wheat production than normal, giving way to its importation for the first time in over a decade. More importantly, an increased wheat yield has become crucial as the world population continues to grow. Recent estimates suggest that as many as a fifth of all calories consumed by people worldwide, come from wheat. In contrast, scientists have noted that the last 15 years have seen little increase in wheat yields. Some scientists have suggested that wheat yields will have to double over the next half-century to keep ahead of population growth. Put another way, the researchers claim that the world will have to produce more wheat over the next 50 years than has been produced over the past 10,000 years in order to keep ahead of demand.Wheat evolved from goat grasses co-incidentally or not, around the same time as people were beginning to learn to grow their own food, the research team notes, most likely in the Middle East. Since that time, humans have reduced the varieties of wheat that are grown, resulting in an erosion of the plant’s natural diversity. Cross breeding modern strains with much older samples that have been preserved in seed banks will bring back some of that diversity, and in this case, hopefully lead to increased yields.Unfortunately because of governmental regulations, the new wheat strain can’t be grown commercially in Britain for five years. That time interval will give scientists and others time to more thoroughly investigate the new strain to ascertain if the initial findings hold. Citation: Scientists announce development of wheat strain that produces 30% greater yields (2013, May 14) retrieved 18 August 2019 from https://phys.org/news/2013-05-scientists-wheat-strain-greater-yields.html No clear evidence that celiac disease increasing because farmers growing higher-gluten wheat (Phys.org) —Researchers in Britain have announced the development of a new strain of wheat that early reports suggest produce 30 percent greater yields than those currently in use. Explore further Credit: Wikipedia. © 2013 Phys.orglast_img read more

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Spiders sprayed with carbon nanotubes spin superstrong webs

first_img Silkworms spinning spider webs As the researchers note, while silk production using silkworms has been quite successful, doing the same to harvest silk from spiders has not, (because of their territorial traits, the complex nature of the silk they make and their cannibalistic tendencies) which is frustrating as the silk they make to spin their webs has so many outstanding qualities. Intrigued by prior research efforts that investigated the possibility of enhancing spider silk by spraying the spiders or feeding them different materials (titanium, zinc, aluminum, lead, etc.) to improve the mechanical, electrical, magnetic or even fluorescent properties of the silk, the researchers wondered what would happen if they sprayed the arachnids, with a graphene or carbon nanotube solution.To find out, they wandered out into the natural environs near their lab and collected a host of cellar spiders and carefully brought them back to their lab. They then proceeded to spray ten of them with a carbon nanotube solution and five with a graphene solution (the particles were 200 to 300 nanometers in width). Sadly, four of the spiders died shortly thereafter, and some produced poor quality webs, but a few of them produced webs that were actually stronger than their normal webs. Testing showed that some of the silk with nanotubes in it was 3.5 times as strong as giant riverine orb spider silk, which is considered the strongest natural spider silk. Also closer examination using Ramen spectroscopy revealed peaks in the silk where the nanotubes were present.The researchers do not know how the carbon in either form wound up in the silk, but have excluded the possibility that it became drenched with it as it exited the spider’s body, the uniformity of the silk was too fine—they think that the spiders pull materials in from their immediate environment and use it as an ingredient in their silk making. Their results suggest it should be possible to produce such silk in small quantities, though it is not clear to what use it would be put. Schematic of the model. Credit: arXiv:1504.06751 [cond-mat.mtrl-sci] Explore further 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. (Phys.org)—A team of researchers working in Italy has found that simply spraying a spider with a carbon nanotube solution can cause the spider to spin stronger webs. In their paper they have uploaded to the preprint server arXiv, the team describes their experiments with both graphene and nanotube solutions and what happened when they sprayed it on ordinary spiders.center_img Citation: Spiders sprayed with carbon nanotubes spin superstrong webs (2015, May 6) retrieved 18 August 2019 from https://phys.org/news/2015-05-spiders-carbon-nanotubes-superstrong-webs.html More information: Silk reinforced with graphene or carbon nanotubes spun by spiders, arXiv, arXiv:1504.06751 [cond-mat.mtrl-sci] http://arxiv.org/abs/1504.06751Here, we report the production of silk incorporating graphene and carbon nanotubes directly by spider spinning, after spraying spiders with the corresponding aqueous dispersions. We observe a significant increment of the mechanical properties with respect to the pristine silk, in terms of fracture strength, Young’s and toughness moduli. We measure a fracture strength up to 5.4 GPa, a Young’s modulus up to 47.8 GPa and a toughness modulus up to 2.1 GPa, or 1567 J/g, which, to the best of our knowledge, is the highest reported to date, even when compared to the current toughest knotted fibres. This approach could be extended to other animals and plants and could lead to a new class of bionic materials for ultimate applications.via Newscientist © 2015 Phys.org Journal information: arXivlast_img read more

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Printable holograms could make holograms more widespread

first_img Explore further More information: Qiancheng Zhao, et al. “Printable ink holograms.” Applied Physics Letters. DOI: 10.1063/1.4928046 © 2015 Phys.org Citation: Printable holograms could make holograms more widespread (2015, August 6) retrieved 18 August 2019 from https://phys.org/news/2015-08-printable-holograms-widespread.html (a) A 2D ink-based holographic signature and (b) a 3D holographic coin, both recorded by single nanosecond-laser interference. Credit: Zhao, et al. ©2015 AIP Publishing Journal information: Applied Physics Letterscenter_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. (Phys.org)—Holograms have a wide variety of applications, from 3D displays to data storage, but the potential applications are currently limited by the complexity and cost of hologram fabrication. In an attempt to simplify the hologram fabrication process, scientists have developed a way to print holograms using a relatively simple and inexpensive laser-printing technique. They hope that the new method will make hologram fabrication more accessible for small-scale and personal use, opening up new types of applications such as integration with smart phones. The researchers, led by Dr. Haider Butt at the University of Birmingham, have published a paper on the printable holograms in a recent issue of Applied Physics Letters.As the researchers explain in their paper, traditional holography fabrication requires specialized knowledge, expensive equipment, and time-consuming recording techniques. Recently, scientists have developed an alternative technique that uses a laser pulse that is split into two beams to create an interference pattern on a surface, producing the characteristic 3D holographic pattern. However, this approach has its own challenges, as it requires precise alignment of the two laser beams and suffers from low light intensity after beam splitting.In the new paper, the researchers have overcome these challenges by developing a single-pulse laser technique that can rapidly print 2D and 3D holograms in seconds on flat or curved surfaces and on a variety of materials. The nanosecond laser can print 1 cm2 of hologram area in just 5 nanoseconds. The researchers explain that the overall speed is not limited by the laser pulse, but by the need to reposition the surface in between lasing, which could potentially be done much faster using robotics.”The technique is slightly different from the conventional methods, which divide a single pulsed beam using beam splitters and then recombine them to produce holograms and nanopatterns,” Butt told Phys.org. “Here we use only a single beam, which is reflected normally from a mirror. The incident and reflected beams interfere, and this interference pattern is used for writing/printing holograms. The technique requires far fewer optical components, it is very simple, reliable, and can be used for ablating a myriad of materials and substrates.”The scientists demonstrated the new technique by printing a holographic 2D signature and a holographic 3D coin. They expect that the method could be especially useful for printing holograms on sensors and “smart” materials that change in response to various stimuli. Printable holograms could also be integrated into smart phones, where, as the researchers explain, they can be used to interpret colorimetric data in pictures. “The holograms printed with this method can be printed using dynamic materials, which are able to respond to any stimuli in their environments,” Butt said. “And they will change their color in response to any environmental changes. Using smart phone cameras and applications, such colorimetric changes can be read, interpreted, and communicated remotely.”Additional applications may include 3D artwork, smart windows, and bio-sensing, among others.”This work can lead to further applications, such as holographic data storage, optical sensors, and printable optical devices,” Butt said. “We and our collaborators are currently pursuing all these research paths and achieving good results.” Multicolor meta-hologram produces light across entire visible spectrumlast_img read more

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Fossil find pushes back date of earliest fused bones in birds by

first_img More information: Min Wang et al. Insight into the growth pattern and bone fusion of basal birds from an Early Cretaceous enantiornithine bird, Proceedings of the National Academy of Sciences (2017). DOI: 10.1073/pnas.1707237114AbstractBird skeletons exhibit remarkable modifications that allow for flight. The most distinguishable features are the fusion of the bones in the hand, feet, and pelvis into composite rigid and bony structures. However, the historical origins of these avian bone fusions remain elusive because of the rarity of transitional fossils and developmental studies on modern birds. Here, we describe an Early Cretaceous bird (120 Mya) that has fully fused alular-major metacarpals and pelvis. We discuss the manus and pelvis fusions across Paravian phylogeny and demonstrate that these features evolved independently across nonavian theropods, Enantiornithes, and Ornithuromorpha. The fusions of these bones are rare in known nonavian theropods and Early Cretaceous birds but are well established among Late Cretaceous and modern birds, revealing a complicated evolution pattern unrecognized previously. We posit that the developments of bone fusion were polymorphic close to the origin of birds, resulting in the varying degrees of fusion in Paraves. However, that development polymorphism appears to be fundamentally restricted along the line to modern birds by the Late Cretaceous, where all birds have a completely fused manus and pelvis. Such changes likely correspond to a refinement of flight capability. Alternatively, the degree of bone fusion in this primitive bird may have been related to modifications in genes or developmental paths. Future studies and fossil discoveries are required to clarify these hypotheses and pinpoint the developmental pathways involving the bone fusions in early avian evolution through to their modern pattern. 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. In order for birds to evolve from land or tree dwelling animals into creatures that can fly, many changes had to occur—they had to become lighter while maintaining a strong skeleton. One of the ways this occurred was through fusion of bones, such as fingers into wingtips, while many other bones were simply lost to evolution. Until now, the consensus among scientists has been that such changes did not occur until just before land-based dinosaurs became extinct. But now, new evidence by the team in China suggests that the time frame will have to be pushed back approximately 40 million years—the bird now represents the oldest known example of fossilized remains showing bone fusion of its major parts.The skeletal remains they were studying were of a bird, Pterygornis dapingfangensi (an Enantiornithe) that once lived in what is now northeastern China. It represents only the second one of its kind ever found. The researchers report that it was in very good condition, so studying it was easy. They report also that the bird very clearly had fused hands and pelvic girdle. More specifically, the fusion was seen in the ilium, the alular-major metacarpals, the ischium and in the pubis pelvis bones. They note that such fusions have rarely been reported with birds of the Early Cretaceous and that the birds appeared to have followed a growth pattern similar to that of modern birds.The finding fills in some of the blanks that have made it difficult to follow the transition of land animals to birds due to a dearth of fossilized evidence. With the finding of the new specimen, more details about bone fusion and the evolutionary history of flight in animals are emerging. © 2017 Phys.org New species of ancient bird discovered in New Mexico Citation: Fossil find pushes back date of earliest fused bones in birds by 40 million years (2017, October 10) retrieved 18 August 2019 from https://phys.org/news/2017-10-fossil-date-earliest-fused-bones.htmlcenter_img Pterygornis. Credit: W. Gao (Institute of Vertebrate Paleontology and Paleoanthropology, Beijing). Journal information: Proceedings of the National Academy of Sciences Explore further (Phys.org)—A trio of researchers with the Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences has found evidence that pushes back the earliest example of fused bones in birds by approximately 40 million years. In their paper published in Proceedings of the National Academy of Sciences, Min Wang, Zhiheng Li and Zhonghe Zhou describe their study of the fossilized remains of a bird dated to approximately 120 million years ago.last_img read more

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Data from Juno shows Jupiter moons causing footprints in aurorae

first_img Citation: Data from Juno shows Jupiter moons causing footprints in aurorae (2018, July 6) retrieved 18 August 2019 from https://phys.org/news/2018-07-juno-jupiter-moons-footprints-aurorae.html A team of researchers with members from Italy, the U.S. and Belgium has discovered that two of Jupiter’s moons cause “footprints” in the planet’s aurorae. In their paper published in the journal Science, the researchers describe what they found and how it helps better understand both the planet and its moons. Journal information: Science All panels are shown in a polar orthographic projection with parallels and meridians overplotted. (A) Footprint of Io on the south pole of Jupiter, as seen on 1 September 2017 at 22:50. The main spot (top-left corner of the image) is followed by a series of regularly spaced secondary spots, which are alternate in displacement above and below the median track (shown in blue). The thin blue arc with dots is the sequence of the predicted Io footprint positions, with dots showing its position every 100 s. Radiances are in mW m−2 sr−1. (B) As in (A), but showing a later image taken at 23:09. The main spot (indicated by a blue arrow) has an oval shape, with an angular offset from the average direction of the tail (median track). (C to E) The Io footprint in the north aurora, observed at 20:43, 20:48 and 20:53 respectively on 1 September 2017. The model is not shown in (C), (D), and (E) as it lies outside of the visible region. The black and white pixels [especially in (D)] are the effect of penetrating radiation affecting the detector. Credit: (c) Science (2018). DOI: 10.1126/science.aat1450 Old data, new tricks: Fresh results from NASA’s Galileo spacecraft 20 years on © 2018 Phys.orgcenter_img On Earth, as the authors note, an aurora is seen as the Northern or Southern lights—dazzling displays of light in the night sky. Jupiter also has aurorae, but they are caused by a different process. Jupiter has a surrounding magnetosphere—plasma carried by the planet’s strong magnetic field. Charged particles from the magnetosphere at times strike the atmosphere of the planet, causing light shows similar to the ones we see on here on Earth. But they have something ours do not—footprints from the planet’s moons. These footprints, the researchers explain, are disturbances in an aurora caused by the presence of a moon—in this case, by Io or Ganymede.The researchers found evidence of the footprints when studying data sent back to Earth by NASA’s Juno space probe. They found that when Io passed close to Jupiter, it caused a double trail of squiggles to appear in a small section of an aurora. The researchers describe it as similar to a Von Kármán vortex—one that streams for hundreds of kilometers. The footprint disappears as the moon moves farther away from the planet.The group also found a footprint created by Ganymede, a spot in an aurora that, upon closer view, turned out to be two spots—the footprint was split in half. The researchers were not able to find a reason for the split, but note that Ganymede is the only moon orbiting Jupiter that has its own magnetic field. This, they suggest, means that the footprint created by the moon represents the interaction of two magnetospheres.The researchers suggest that learning more about the footprints caused by Jupiter’s moons will help to understand how the moons interact with the planet and how strong magnetic forces in a natural environment interact. They also note that neither footprint was in the location that had been predicted, which indicates that models built to describe such events will need to be adjusted. Explore further More information: A. Mura et al. Juno observations of spot structures and a split tail in Io-induced aurorae on Jupiter, Science (2018). DOI: 10.1126/science.aat1450AbstractJupiter’s aurorae are produced in its upper atmosphere when incoming high-energy electrons precipitate along the planet’s magnetic field lines. A northern and a southern main auroral oval are visible, surrounded by small emission features associated with the Galilean moons. We present infrared observations, obtained with the Juno spacecraft, showing that in the case of Io, this emission exhibits a swirling pattern that is similar in appearance to a von Kármán vortex street. Well downstream of the main auroral spots the extended tail is split in two. Both of Ganymede’s footprints also appear as a pair of emission features, which may provide a remote measure of Ganymede’s magnetosphere. These features suggest that magnetohydrodynamic interaction between Jupiter and its moon is more complex than previously anticipated. 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

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Repeating History on Delhi stage

first_imgOrganised by Films andTheatre Society, the two plays gearing up to put some impressive shows are Arjun Ka Beta and Draupadi.The play Arjun Ka Beta is a poetic rendition of a conversation between king Yudhisthira and the great warrior Bheeshama (Son of Ganga). It is a word-to-word description of the bravado of great Abhimanyu given to Bheeshma by Yudhishtira who also shares his inability to face Arjun who would soon be coming back from the battlefield and ask for his son. Also Read – ‘Playing Jojo was emotionally exhausting’This one hour 20 minutes Hindi play subtly shows the various philosophies of a ‘chakravyuh’ which hold good in the lives of all of us.The next in line is Draupadi which takes excerpts from the story of Draupadi as known to everybody and adds to it some imaginative sequences to bring out the real essence of association between Draupadi and today’s women. This juxtaposing makes this work fit to be called an imaginative re-telling of certain chapters from Draupadi’s life. Head over for an interesting history lesson this weekend.WHEN: 21 December and 22 DecemberTIMINGS: 6.30 onwards (Both days)WHERE: LTG, Mandi houselast_img read more

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CBI Special Director to hold meet on ongoing cases

first_imgKolkata: The Special Director of the Central Bureau of Investigation (CBI), Rakesh Asthana, will hold a meeting with investigating officers of different cases, including those of Saradha chit fund scam and Narada sting operation, in Kolkata on Wednesday. There will also be discussion on the Rose Valley scam and other cases that the central investigating agency is probing. Sources said that this is the first time when such a meeting is going to be held in the city. On Wednesday, Asthana will be holding the meeting in CBI’s office at Nizam Palace. Asthana will discuss all the matters of all the cases with their Investigating Officers (IOs). It may be mentioned that there were several issues in connection with cases, including that of Narada. It may be mentioned that Asthana will reach Kolkata on Tuesday and he will be holding the meeting on Wednesday. On Monday, he was in Bhubaneswar and held a meeting with officers there. The meeting was held in connection with 30 chit fund cases that took place in Odisha. It may be mentioned that authorities of Apple have stated that they will not be providing the details which CBI had sought in connection with Mathew Samuel, former Narada CEO’s iPhone.last_img read more

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