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3 months ago
NASA is getting ready to launch the Transiting Exoplanet Survey Satellite, or TESS, which will head out into space searching for planets that are smaller than Neptune, with a radius less than about four times that of Earth. Scientists will use other telescopes to measure the masses of 50 of the planets TESS finds, to see if they are habitable places for life as we know it, reports The Los Angeles Times.
“It’s very exciting,” MIT astrophysicist George Ricker said to the LA Times. “We’re getting a chance to potentially answer a question that humanity’s always been interested in: What’s in the sky? And are there other beings, other places like Earth?”
NASA has been trying to answer these questions for years, using the telescopes Hubble and Spitzer to search for exoplanets. Meanwhile, the Kepler Space Telescope’s mission has detected 2,342 confirmed and 2,235 candidate exoplanets. TESS is going to up that mission. Kepler stared at one small patch in the sky, whose stars are up to 3,000 light-years away. TESS will look in nearly all directions and will target stars that are less than 300 light-years away.Read the full story at The Los Angeles Times | <urn:uuid:bc5bf302-b54c-4db0-bda3-69340a8e6f24> | 3.265625 | 272 | Truncated | Science & Tech. | 57.008571 | 95,548,686 |
Quakes can lead to more quakes, scientists suggest
The deadly earthquake that struck in Chile on Saturday was probably due to stresses built up deep in the Earth's crust by the largest recorded temblor ever recorded in the same coastal nation 50 years ago, scientists proposed Monday as an explanation for the most recent devastating event.
Similar stress from early historic earthquakes in California could well have helped trigger quakes like the damaging Coalinga (Fresno County) temblor of 1983 that destroyed the small city's downtown, they said.
Ross S. Stein, a research geophysicist at the U.S. Geological Survey in Menlo Park, and Jian Lin, a geologist from the Woods Hole Oceanographic Institution on Cape Cod, are conferring about the latest Chile quake in Stein's office this week, and in interviews Monday they discussed the concept they call "stress triggering."
The monstrous Chile quake in 1960, with a magnitude of 9.5, created strong stress deep in the ground at both ends of the rupture zone, and Saturday's temblor relieved that stress in one lurch, Lin said.
Although unrelated on the far side of the Pacific, the same kind of stress inside a similar giant rupture zone beneath Indonesia built up and led to the great tsunami-generating Sumatra quake of 2004, Lin said. And that stress then helped trigger the next major earthquake that hit the same island on a different fault only three months later, he said.
"But just why it took 60 years for stress to trigger Saturday's quake in Chile, while it took only three months to rupture the ground in Indonesia, we just don't have enough science yet to understand," Lin said.
The January quake in Haiti that has claimed an estimated 230,000 lives so far could also have been triggered, at least in part, by stress built up during three earlier major quakes on that island in 1751, and two others that struck within months of each other in 1770, Stein suggested.
"Haiti right now remains vulnerable to another large quake closer to Port au Prince, although the chance is quite small - a few percent, perhaps," he said.
Earthquake studies in Northern California relate many recent events to a remote part of the San Andreas Fault where the Fort Tejon quake of 1857 struck with a magnitude later calculated at 7.9.
That quake, Stein said, created stress on the Coalinga fault that resulted in the devastating magnitude 6.7 quake there 126 years later.
Stress inside the fault generated by the Fort Tejon quake also helped rupture the White Wolf fault in Kern County and caused the Tehachapi earthquake of 1952 which killed 14 people in that small town, he said.
Still another example of "stress transfer," Stein said, was the powerful Landers quake of 1992 with a magnitude of 7.3 that shook all of Southern California. Only three hours later, stress within that fault caused the Big Bear quake 22 miles away, and seven years later set off the larger Hector Mine quake with a magnitude of 7.1 in the Mojave Desert east of Barstow.
"Whenever an earthquake strikes," Stein said, "the probabilities of another quake are higher. Like aftershocks, they never disappear. But our hypothesis of stress transfer triggering quakes is still being hotly debated; it will take a lot more science to prove it."
Stein and Lin first published their report in 2004 in the Journal of Geophysical Research. | <urn:uuid:7ebacf4c-bae9-4bee-acdb-732d974b34a9> | 3.28125 | 712 | News Article | Science & Tech. | 53.7116 | 95,548,693 |
This article presents a method of adjusting steering mirrors to achieve alignment in just two adjustments. The steering mirrors are adjusted in a way that creates a point that the beam always passes through. The beam pivots about this point as the pointing angle is changed. If the fixed point is located at the center of an aperture, the beam can then be pointed straight to a second aperture, thus completing the alignment. The pivot effect happens naturally when the second mirror is adjusted proportionally more than the first. If the extra amount was 10% and the adjustment to mirror 1 was 3 turns then mirror 2 gets 3.3 turns. The first three turns on both mirrors translates the beam sideways and parallel. The extra 0.3 turns the beam inward slightly in the direction opposite translation, so it crosses over the original beam line at a point that remains fixed. Further adjustments at this same ratio will change the angle through that point, and it appears like it pivots. The extra portion is the ratio A / B, which is the distance between steering mirrors divided by the distance from mirror 2 to the pivot.
Paul S. Thompson,
"Pivoting a beam about a fixed point with steering mirrors," Optical Engineering 57(2), 025106 (27 February 2018). https://doi.org/10.1117/1.OE.57.2.025106
. Submission: Received: 3 December 2017; Accepted: 6 February 2018
Received: 3 December 2017; Accepted: 6 February 2018; Published: 27 February 2018 | <urn:uuid:6a20aada-0bea-4c63-a5c9-2c5a237db753> | 3.09375 | 310 | Academic Writing | Science & Tech. | 70.677366 | 95,548,710 |
Drones can be used to monitor wildlife more accurately than traditional counting approaches, a study has found.
Researchers used a few thousand rubber ducks to test the usefulness and accuracy of drones for wildlife monitoring compared to a group of experienced wildlife spotters.
"For a few years now, drones have been used to monitor different animals that can be seen from above, including elephants, seals and nesting birds,"said Jarrod Hodgson from University of Adelaide in Australia.
"However, until now, the accuracy of using drones to count wildlife was unclear," said Hodgson.
"We needed to test the technology where we knew the correct answer. We couldn't use wild animals because we could never be sure of the real number of individuals present," he said.
Experienced wildlife spotters challenged those who counted birds from drone imagery to see which group could get closest to the actual number of fake birds.
The ground spotters counted the fake birds using binoculars or telescopes. Meanwhile, a drone was flown over the beach, taking pictures of the birds from the sky at different heights.
Citizen scientists then tallied the number of birds they could see in the photos. The drone approach won.
"We found it is more accurate and more precise to have people count birds from the drone imagery than to do it on location," Hodgson said.
However, counting birds in photos takes a long time - and citizen scientists can get tired.
Researchers made a computer algorithm to count the ducks automatically, which yielded results just as good as humans reviewing the imagery.
"With so many animals across the world facing extinction, our need for accurate wildlife data has never been greater," Hodgson said.
"Accurate monitoring can detect small changes in animal numbers. That is important because if we had to wait for a big shift in those numbers to notice the decline, it might be too late to conserve a threatened species," he said.
"Our results show that monitoring animals with drones produces better data that we can use to proactively manage wildlife," he added.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.) | <urn:uuid:21f6dae1-2f6d-4840-923d-2377ceeac4c0> | 3.609375 | 439 | Truncated | Science & Tech. | 40.378809 | 95,548,736 |
A study shows for the first time that X-ray lasers can be used to generate a complete 3-D model of a protein without any prior knowledge of its structure.
This 3-D rendering of a lysozyme molecule shows two gadolinium atoms bound to it. Researchers soaked lysozyme crystals in a solution containing the metal gadolinium to help improve imaging quality in an experiment at SLAC's Linac Coherent Light Source X-ray laser. The experiment proved that LCLS can resolve the lysozyme structure without using data obtained earlier, and researchers hope to use similar techniques to reconstruct important unsolved proteins.
Credit: Max Planck Society
An international team of researchers working at the Department of Energy's (DOE) SLAC National Accelerator Laboratory produced from scratch an accurate model of lysozyme, a well-studied enzyme found in egg whites, using the Linac Coherent Light Source (LCLS) X-ray laser and sophisticated computer analysis tools.
The experiment proves that X-ray lasers can play a leading role in studying important biomolecules of unknown structure. The special attributes of LCLS, which allow the study of very small crystals, could cement its role in hunting down many important biological structures that have so far remained out of reach because they form crystals too small for analysis with conventional X-ray sources.
"Determining protein structures using X-ray lasers requires averaging a gigantic amount of data to get a sufficiently accurate signal, and people wondered if this really could be done," said Thomas Barends, a staff scientist at the Max Planck Institute for Medical Research in Germany who participated in the research. "Now we have experimental evidence. This really opens the door to new discoveries."
Collaborators from SLAC and Arizona State University also participated in the research, which was published Nov. 24 in Nature.
The underlying technique, called X-ray crystallography, is credited with solving the vast majority of all known protein structures and is associated with numerous Nobel Prizes since its first use just over a century ago.
Protein structures tie directly to their functions, such as how they bind and interact with other molecules, and thus provide vital details for developing highly targeted disease-fighting drugs. But many protein structures that are considered promising targets for new medicines remain unknown, mainly because they don't form crystals that can be deciphered with existing techniques.
This work is the latest in a rapid progression of important advances at LCLS, which began operations for users in 2010. For example, last year researchers used LCLS to determine the structure of an enzyme that can hold African sleeping sickness in check, which makes it a promising drug target. However, those previous studies relied on data from similar, known structures to fill in common data gaps.
For this study the researchers chose lysozyme, whose structure has been known for decades, because it offered a good test of whether their method produced accurate results. They soaked lysozyme crystals in a solution containing gadolinium, a metal that bonded with the lysozyme to produce a strong signal when subjected to the intense X-ray light. It was this signal from the gadolinium atoms that enabled exact reconstruction of the lysozyme molecule.
The team hopes to adapt and refine the technique to explore more complex proteins such as membrane proteins, which serve a range of important cellular functions and are the target of more than half of all new drugs in development. Only a small fraction of the thousands of membrane proteins have been completely mapped.
"This study is an important milestone on which the field will build further," said John R. Helliwell, emeritus professor of chemistry at the University of Manchester and formerly a director of the Synchrotron Radiation Source at Daresbury Laboratory in England. "The X-ray laser is bringing new opportunities and new ideas for 3-D structure determination of ever-smaller samples. The use of computers to automate this process is a triumph."
Barends said the latest results are a remarkable achievement, given that it took just a few years for LCLS to reach this milestone. "Further improvements in X-ray detectors, software and crystal formation and delivery techniques should enable more discoveries in the coming years," he said.
SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the U.S. Department of Energy Office of Science. To learn more, please visit http://www.slac.stanford.edu.
SLAC's LCLS is the world's most powerful X-ray free-electron laser. A DOE national user facility, its highly focused beam shines a billion times brighter than previous X-ray sources to shed light on fundamental processes of chemistry, materials and energy science, technology and life itself. For more information, visit lcls.slac.stanford.edu.
DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
Citation: T. Barends et al., Nature, 24 November 2013 (10.1038/nature12773)
Andy Freeberg | EurekAlert!
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:826f7da4-451d-4916-85e7-2405ffdc9c75> | 3.59375 | 1,755 | Content Listing | Science & Tech. | 38.796318 | 95,548,738 |
The last piece of a supernova puzzle
A team led by Gastón Folatelli at the Kavli IPMU, the University of Tokyo, has found evidence of a hot binary companion star to a yellow supergiant star, which had become a bright supernova. The existence of the companion star had been predicted by the same team on the basis of numerical calculations.
Images in the top row depict an artist's conception of the supernova explosion process. The corresponding images below were taken with the Hubble Space Telescope. Left: Just before the supernova explosion. A yellow supergiant is shining. Middle: The supernova exploding (the bottom image shows the fading supernova after the explosion). Right: A bright blue star observed.
Credit: Top image: Kavli IPMU Bottom image: NASA/Kavli IPMU/Gastón Folatelli
This finding provides the last link in a chain of observations that have so far supported the team's theoretical picture for this supernova. The results are published in the Astrophysical Journal Letters and have wide implications for our knowledge of binary systems and supernova mechanisms.
"One of the most exciting moments in my career as an astronomer was when I displayed the newly arrived HST images and saw the object right there, where we had anticipated it to be all along" said Gastón Folatelli , who led the efforts to obtain the new Hubble Space Telescope (HST) observations.
The question of how massive stars spend their short lives until they become supernovae is of great interest for astrophysicists. According to the standard theory, which is only applicable to isolated stars, only cool and extended (red supergiants) or hot and blue (Wolf-Rayet stars) are able to become supernovae.
However, growing evidence suggests that most massive stars are not lonely singles but they belong to close binary systems with profuse interactions. Episodes of mass transfer between the members of binary star systems affect the way the stars evolve, meaning that there are a great many more potential scenarios for the final stages of supernova progenitors.
The nearby supernova SN 2011dh, which occurred in 2011 in the well-known whirlpool galaxy M51, which is about 24 million light-years away from the earth, presented an excellent example that could not be explained by the standard theory. What appeared to be a yellow supergiant star was detected at the location of the supernova in images obtained before the explosion, but yellow supergiant stars in isolation were not thought capable of becoming supernovae.
Controversy arose in the astronomy community with several experts proposing that the actual progenitor must have been an unseen bright blue object, such as a Wolf Rayet star. However, the team led by Melina C. Bersten at Kavli IPMU and Omar Benvenuto at the University of La Plata, Argentina, showed that the exploding star must have been extended, like a yellow supergiant, and that it must have belonged to a binary system (see web release on September 28 2012: http://www.ipmu.jp/node/1404). "We produced detailed models that self-consistently explained every property of SN 2011dh through the explosion of a yellow supergiant star in a binary system," remarked Melina C. Bersten.
In March 2013, the proposal of Benvenuto, Bersten and collaborators was given substantial support when the disappearance of the yellow supergiant was observed, indicating that it and not a bright blue star was the exploding object (see web release on Apr. 5 2013: http://www.ipmu.jp/node/1537). "At that time there was just one piece of the puzzle missing to confirm our model: we had to find the companion star that, according to our calculations, was a hot, compact object," said Omar Benvenuto.
With that goal, the group set out to obtain HST observing time, which was granted in 2013 and recently executed on August 7, 2014. Images were obtained in the ultraviolet regime, where the companion star was expected to be most clearly visible. A point source was clearly detected in the new images at the exact location of the supernova (see announcement in http://www.astronomerstelegram.org/?read=6375). "To our excitement, the object had the properties predicted by the models," explained Schuyler Van Dyk, of Caltech, who was in charge of the image analysis. Folatelli and collaborators judged it unlikely that the detection was due to some other contaminating source.
Further HST observations were recently obtained in the optical range by another European team. "When available, such data will not only serve to definitely validate the existence of the companion star, but also they will provide critical information to refine the binary model originally proposed by our team", said Ken'ichi Nomoto from Kavli IPMU. This is a unique opportunity to make such a detailed study of the progenitor of a supernova. The results will have important implications for our knowledge of stellar evolution and its connection with supernova properties.
The case of SN 2011dh beautifully illustrates the advantages of an active feedback between theory and observation. "As a scientist, for me it is like a dream come true to make a prediction and have it confirmed step by step as the supernova evolves and facts are revealed. It is a rare case for astronomy, where events usually take much longer to develop. We are very happy with how the story of SN 2011dh proceeded," concluded Melina C. Bersten.
Gastón Folatelli, Melina C. Bersten, Omar G. Benvenuto, Schuyler D. Van Dyk, Hanindyo Kuncarayakti, Keiichi Maeda, Takaya Nozawa, Ken'ichi Nomoto, Mario Hamuy, and Robert M. Quimby, "A Blue Point Source at the Location of Supernova 2011dh," Astrophysical Journal Letters.
Gastón Folatelli, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo
Melina C. Bersten, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo
Ken'ichi Nomoto, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo
Marina Komori, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo
+81-4-7136-5977 (office), +81-80-9343-3171 (mobile), email@example.com
Aya Tsuboi, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo
ABOUT KAVLI IPMU
Kavli IPMU (Kavli Institute for the Physics and Mathematics of the Universe) is an international research institute with English as its official language. The goal of the institute is to discover the fundamental laws of nature and to understand the Universe from the synergistic perspectives of mathematics, astronomy, and theoretical and experimental physics. The Institute for the Physics and Mathematics of the Universe (IPMU) was established in October 2007 under the World Premier International Research Center Initiative (WPI) of the Ministry of Education, Sports, Science and Technology in Japan with the University of Tokyo as the host institution. IPMU was designated as the first research institute within Todai Institutes for Advanced Study (TODIAS) in January 2011. It received an endowment from The Kavli Foundation and was renamed the "Kavli Institute for the Physics and Mathematics of the Universe" in April 2012. Kavli IPMU is located on the Kashiwa campus of the University of Tokyo, and more than half of its full-time scientific members come from outside Japan.
Kavli IPMU Website - http://www.ipmu.jp/
Marina Komori | Eurek Alert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
17.07.2018 | Information Technology
17.07.2018 | Materials Sciences
17.07.2018 | Power and Electrical Engineering | <urn:uuid:03acabb1-e4a2-4a4d-b685-8d7e99f2040d> | 3.46875 | 2,281 | Content Listing | Science & Tech. | 36.377165 | 95,548,752 |
Species Detail - Wild Parsnip (Pastinaca sativa) - Species information displayed is based on all datasets.
Terrestrial Map - 10kmDistribution of the number of records recorded within each 10km grid square (ITM).
Marine Map - 50kmDistribution of the number of records recorded within each 50km grid square (WGS84).
Pastinaca sativa subsp. sylvestris, Pastinaca sativa var. sylvestris, Pastinaca sylvestris
Invasive Species: Invasive Species || Invasive Species: Invasive Species >> Medium Impact Invasive Species
15 March (recorded in 2003)
29 October (recorded in 1992)
National Biodiversity Data Centre, Ireland, Wild Parsnip (Pastinaca sativa), accessed 22 July 2018, <https://maps.biodiversityireland.ie/Species/29129> | <urn:uuid:eca890ef-6a37-4eb7-a782-c61d03a0ac56> | 3.09375 | 192 | Structured Data | Science & Tech. | 19.407368 | 95,548,788 |
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Asuswrt is a unified firmware developed by Asus for use in their recent routers. The firmware was originally based on Tomato-RT/Tomato-USB, but has changed a lot since the original code fork. Asus started using this firmware with the RT-N66U, but they also migrated some of their previous models to this new firmware, like the DSL-N55 or the RT-N56.
Being mostly based on GPL code, almost all the source code and all necessary build tools are available from their website. There are a few proprietary components that are closed source (like the wireless drivers from Broadcom/Ralink). In these cases, Asus includes binary-only versions of these files. In the end, their GPL release includes everything needed to completely recompile a working firmware, with the exact same features as found in their firmware releases.
One big advantage of Asus going with a unified firmware is that they have one global code base for all their supported routers (with a few specialized branches as needed by some specific models). That way, general bug fixes and improvements can automatically be applied to all other supported devices. Similarly, new features added for one model can often be enabled for other models as well (provided the hardware can support it.) And finally, it makes it easier for Asus to support older models for a longer time than if they were all running their own unique firmware.
Asuswrt-merlin takes advantage of the fact that complete source code is available from Asus by building on top of it. Asuswrt-merlin is my personal project, originally done for the RT-N66U, and eventually extended to support other flagship routers from Asus.
The general goal of this project is to provide an alternative to the original firmware, and remain in-sync with Asus's own development, so new features and bugfixes development by them can trickle down into Asuswrt-Merlin. This means there are some very strict design guidelines behind this project:
Stay as close as possible to the original firmware. By limiting the amount of sweeping changes made to the code, it means that whenever Asus releases a new version of Asuswrt, it generally takes only a few hours of work to merge their latest changes into Asuswrt-merlin (a bit more if it's a major new release from Asus).
The goal is to improve, not to replace the original firmware's functionality Projects like DD-WRT and Tomato have existed for years, and benefit from those years of development to offer a lot of new features. There is no point in reinventing the wheel - people looking for a completely different firmware with tons of advanced features should look at those excellent and well-established projects.
Priorities: Stability > performance > features. Fewer changes to the code means fewer chances that new bugs might be introduced. A router firmware is the core of your home network. It must be rock-stable above all. And performance optimizations can have unexpected side-effect when dealing with things that aren't fully understood.
Targeting the novice and average user. Asuswrt is designed to target both the novice and the average users. This project will aim at the same target userbase. There is enough doors left open with Entware and user-scripts so advanced users can fulfill their own requirements themselves. Not overcrowding the web UI with esoteric features will ensure that novice users won't be scared away.
Thanks to Entware/Optware and user-scripts, many features not integrated in the firmware can be manually added. If you are advanced enough to need a feature, you will quite often be skilled enough to manually add it, or follow someone else's instructions on how to implement what you are looking for. | <urn:uuid:9c69d126-8e8c-4017-bf5f-f21953e8ca65> | 2.53125 | 797 | About (Org.) | Software Dev. | 36.790437 | 95,548,799 |
Winter 2017-2018 A Look Back Part 1
A sharp, prolonged siege of Arctic air shattered daily, even April monthly records in the Northeast and Great Lakes as April 2016 kicked off.
Subzero cold was observed near the Canadian border in northern Michigan, northern New York and northern Maine Tuesday morning. Daily record lows were set in parts of the Northeast Wednesday morning and the Upper Midwest Saturday morning.
(MORE: Is the Polar Vortex a Factor?)
The cold blast may be short-lived, but was one of the factors that allowed for a series of late-season snow events to affect portions of the Great Lakes and Northeast.
(MORE: Trail of Snow from Midwest to Northeast)
A few daily record low temperatures were set Sunday morning including Dubois, Pennsylvania (12 degrees); Youngstown, Ohio (15 degrees); Erie, Pennsylvania (20 degrees); Bluefield, West Virginia (20 degrees tied).
Temperatures dropped into the 30s in many areas in the Tennessee Valley, north Georgia and the piedmont and coastal plain of the Carolinas.
Lows Saturday morning, April 9, dipped into the teens below zero in the Arrowhead of Minnesota. Duluth, Minnesota (4 degrees) and St. Cloud, Minnesota (13 degrees) set new daily record lows.
Wednesday, April 6, record lows were tied or set in the following locations:
- Concord, New Hampshire: 11 degrees
- Providence, Rhode Island: 18 degrees
- Pomona, New Jersey: 22 degrees
- Baltimore (BWI Airport), Maryland: 24 degrees
- Salisbury, Maryland: 24 degrees
- Washington (Dulles Airport): 24 degrees (tied)
- Lynchburg, Virginia: 25 degrees (tied)
- Georgetown, Delaware: 26 degrees
- Richmond, Virginia: 27 degrees (tied)
- Fayetteville, North Carolina: 31 degrees (tied)
Helped by a cold air mass refrigerated by a fresh snow cover from Winter Storm Ursula, Concord, New Hampshire shattered their all-time record low for the month of April Tuesday morning, dipping to a bone-chilling 4 degrees. The previous April cold record, 7 degrees, had stood since April 1, 1874, during the presidency of Ulysses S. Grant.
Syracuse, New York, tied its second coldest April temperature on record Tuesday morning, dipping to 9 degrees. It was only the third April low in the single digits, there, dating back to 1902.
Some other daily record lows on April 5 included:
- Negaunee Township, Michigan (NWS office): -7 degrees (second coldest temperature so late in the season, there)
- Glens Falls, New York: 7 degrees
- Binghamton, New York: 12 degrees
- Watertown, New York: 12 degrees (tied)
- Albany, New York: 14 degrees
- Rochester, New York: 14 degrees
In addition, several locations on April 4 saw record cold high temperatures. Among those cities were Concord, New Hampshire (26 degrees), Hartford, Connecticut (27 degrees), Portland, Maine (25 degrees), Providence, Rhode Island (31 degrees), and Worcester, Massachusetts (22 degrees).
MORE ON WEATHER.COM: Winter Storm Ursula (PHOTOS) | <urn:uuid:40176caa-9273-47d5-865d-b3bb72340137> | 2.515625 | 681 | News Article | Science & Tech. | 42.967484 | 95,548,802 |
Study about the impact of changes in land use on the concentration of carbon dioxide in the atmosphere -- publication in Environmental Research Letters
Climate change is heavily related to the increase of CO2 in the atmosphere. During photosynthesis, plants absorb some of the industrial CO2 emissions from the atmosphere, making them contribute significantly to climate protection.
"The CO2 increase in the atmosphere is currently lower than to be expected from anthropogenic emissions," says Professor Almut Arneth from the Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU) at KIT Campus Alpin in Garmisch-Partenkirchen. 20 to 25 percent of the CO2 released by humans into the atmosphere is currently being absorbed by plants. "This effect curbs climate change; without it global warming would have progressed further by now," the scientist says. "The question is whether it will stay this way in the next few decades."
A research group led by Arneth and Dr Benjamin Quesada at IMK-IFU has dealt with the impact of changes in land use on the expected concentration of carbon dioxide - in other words CO2 projection - in the earth's atmosphere.
Their study titled "Potential strong contribution of future anthropogenic land-use and land-cover change to the terrestrial carbon cycle" published in Environmental Research Letters shows that changes in land use have a significant impact on future CO2 absorption from the atmosphere.
If forests are cut down in favor of arable land and pasture land, it reduces the capacity of plants and soil to take up CO2. "The wood in a forest can store more CO2 than corn for example," explains Arneth who in her research deals with the interaction between the atmosphere, plants and soil.
If deforestation were to continue, it could even be expected that large parts of the tropics will change from a CO2 basin - which absorbs more CO2 than it releases - to a CO2 source.
Researchers at KIT have summarized the results of five common climate models and looked at seven variables for 25 world regions to better understand the extent to which different changes in land use have an impact on CO2 storage in vegetation, and as a result on the concentration in the atmosphere. The scenarios differ, for example, in how much leaf area there is in relation to soil area, how much the relevant plants grow, and how long a plant grows before it dies and releases CO2 into the atmosphere.
All the models were fed with the same assumptions to limit model-related uncertainties through the summary and detailed systematic analysis of the results. This makes the study more significant than previous investigations which were based only on individual models.
"We have shown how important it is to include the expansion of agricultural land in climate projections and to adapt the models; there is still a lot of room for improvement," says the environmental researcher. "This study confirms how important it is to work toward ensuring that deforestation in the tropics and globally is reduced or stopped," says Arneth.
Benjamin Quesada, Almut Arneth, Eddy Robertson and Nathalie de Noblet: Potential strong contribution of future anthropogenic land-use and land-cover change to the terrestrial carbon cycle. Environmental Research Letters, 2018. http://iopscience.
More information on the KIT Climate and Environment Center: http://www.
Being „The Research University in the Helmholtz Association", KIT creates and imparts knowledge for the society and the environment. It is the objective to make significant contributions to the global challenges in the fields of energy, mobility and information. For this, about 9,300 employees cooperate in a broad range of disciplines in natural sciences, engineering sciences, economics, and the humanities and social sciences. KIT prepares its 25,500 students for responsible tasks in society, industry, and science by offering research-based study programs. Innovation efforts at KIT build a bridge between important scientific findings and their application for the benefit of society, economic prosperity, and the preservation of our natural basis of life.
Monika Landgraf | EurekAlert!
What does global climate have to do with erosion rates? Not so much, say scientists
05.07.2018 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
Soil weathering: The puppet master of carbon cycling?
04.07.2018 | Universität Augsburg
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
Sizes and shapes of nuclei with more than 100 protons were so far experimentally inaccessible. Laser spectroscopy is an established technique in measuring fundamental properties of exotic atoms and their nuclei. For the first time, this technique was now extended to precisely measure the optical excitation of atomic levels in the atomic shell of three isotopes of the heavy element nobelium, which contain 102 protons in their nuclei and do not occur naturally. This was reported by an international team lead by scientists from GSI Helmholtzzentrum für Schwerionenforschung.
Nuclei of heavy elements can be produced at minute quantities of a few atoms per second in fusion reactions using powerful particle accelerators. The obtained...
A team headed by the TUM physicists Alexander Holleitner and Reinhard Kienberger has succeeded for the first time in generating ultrashort electric pulses on a chip using metal antennas only a few nanometers in size, then running the signals a few millimeters above the surface and reading them in again a controlled manner. The technology enables the development of new, powerful terahertz components.
Classical electronics allows frequencies up to around 100 gigahertz. Optoelectronics uses electromagnetic phenomena starting at 10 terahertz. This range in...
Russian researchers together with their French colleagues discovered that a genuine feature of superconductors -- quantum Abrikosov vortices of supercurrent -- can also exist in an ordinary nonsuperconducting metal put into contact with a superconductor. The observation of these vortices provides direct evidence of induced quantum coherence. The pioneering experimental observation was supported by a first-ever numerical model that describes the induced vortices in finer detail.
These fundamental results, published in the journal Nature Communications, enable a better understanding and description of the processes occurring at the...
03.07.2018 | Event News
28.06.2018 | Event News
28.06.2018 | Event News
06.07.2018 | Information Technology
06.07.2018 | Materials Sciences
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The world`s oldest fossilised vomit, believed to have come from a large marine reptile that lived 160 million years ago, has been discovered in a clay quarry in Peterborough by the University of Greenwich`s Professor Peter Doyle and Dr Jason Wood of the Open University.
The vomit contains the remains of dozens of belemnites - squid-like shellfish that lived in abundance in the seas around what is now Britain. The belemnites were eaten in great numbers by ichthyosaurs, large marine reptiles (related to land-dwelling dinosaurs) common in the warm seas of the Jurassic era, similar in size and shape to dolphins.
Having eaten dozens of belemnites, an ichthyosaur would regurgitate their indigestible bullet shaped shells in much the same way that an owl does after eating a mouse whole. It is these shells that have been discovered in the fossil vomit.
Nick Davison | alphagalileo
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
Drones survey African wildlife
11.07.2018 | Schweizerischer Nationalfonds SNF
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
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12°C / 54°F
The measurements for the water temperature in Kvalsund, Finnmark are provided by the daily satellite readings provided by the NOAA. The temperatures given are the sea surface temperature (SST) which is most relevant to recreational users.
The graph below shows the range of monthly Kvalsund water temperature derived from many years of historical sea surface temperature data.
These average ocean temperatures for Kvalsund are calculated from several years of archived data.
Whilst sea temperatures for Kvalsund are as accurate as current data allows, there may be slight local and regional variations depending on conditions. Time of day and wind direction may have a temporary local effect as can water flows from neraby rivers. | <urn:uuid:5b2a529e-2941-4cc6-a2e1-e1da96b95fb8> | 2.5625 | 146 | Knowledge Article | Science & Tech. | 23.627115 | 95,548,821 |
People always have had to confront themselves with the unforeseeable behaviour of the environment and climatic variability. However, for the first time in the history of our planet, climatic change is today caused by human activity. This situation of global crisis is caused by a series of factors that make of the present emergency a new scenario, exposing entire areas of the planet to the risk of lack of water and desertification. However, desert and desertification are two different things. The desert is characterised by a precise ecological balance established in the course of time by specific climatic conditions. These precise conditions have generated knowledge capable of facing adversities with appropriate techniques for capturing and distributing water, for preserving soil, for recycling and for the economical use of energy. The paper analyse the different solutions adopted in ancient periods in order to cope with water scarcity. In particular the study compares the Neolithic experiences in the Puglia Region and in the Sassi di Matera (Italy) with similar structures in the rest of Mediterranean. These traditional solutions are today proposed in a new innovative form to cope with environmental crises.
Ancient water management techniques to counteract drought and desertification in the Mediterranean
Pietro Laureano; Ancient water management techniques to counteract drought and desertification in the Mediterranean. Water Science and Technology: Water Supply 1 September 2010; 10 (4): 495–503. doi: https://doi.org/10.2166/ws.2010.103
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Chemical characterization of surface snow in Istanbul (NW Turkey) and their association with atmospheric circulations
- 197 Downloads
The understanding of the impurities in natural snow is important in realizing its atmospheric quality, soil characteristics, and the pollution caused to the environment. Knowledge of the occurrence of major ions and trace metals in the snow in the megacity of Istanbul is very limited. This manuscript attempts to understand the origin of major soluble ions (fluoride, acetate, formate, chlorite, chloride, nitrite, chlorate, bromide, nitrate, sulfate, phosphate, and perchlorate) and some trace metals (Fe, Mn, Cd, Co, Ni, Pb, Zn, Cu) in winter surface snow, collected in Istanbul, Turkey. The sampling of the surface snow was conducted after each precipitation during the winter of 2015–2016 at three sites in the city. Besides the statistical evaluation of the major ions, and some trace metal concentrations, the chemical variations along with atmospheric circulations, which are important modification mechanisms that influence the concentrations, were investigated in the study. At examined locations and times, 12 major anions were investigated and in these anions fluoride, chlorite, chlorate, bromide, and perchlorate in the snow samples were below the detection limit; only SO4 2−, NO3 −, and CI− were found to be in the range of 1.11–17.90, 0.75–4.52, and 0.19–3.01 mg/L. Also, according to the trace element determination, the concentration was found to be 29.2–53.7, 2.0–16.1, 1.0–2.2, 50.1–71.1, 24.2–35.2, ND–7.9, 43.2–106.6, and 3.0–17.7 μg/L for Fe, Mn, Cd, Co, Ni, Pb, Zn, and Cu, respectively. The major anions and investigated trace elements here originated mainly from anthropogenic and atmospheric circulation and mainly influenced by northerly and southerly circulation patterns. While the main limitations in the present study may be the low number of samples that may not be entirely representative, accurately reflect identification, or support other previously observed local measurements, we believe that the type of data presented in this study has the potential to be used in the field of environmental risk assessment and, as result, for human health.
KeywordsIstanbul Snow Major ions Trace elements Meteorological conditions Atmospheric circulations
The author would like to express their thanks to Prof. Dr. Hasan Saygin (Istanbul Aydin University) for the contribution on the source and sink relation.
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Despite the poor conditions this summer, Butterfly Conservation’s Big Butterfly Count 2015 attracted a record number of participants, with more than 52,000 people taking part in this year’s event. Though survey numbers were up, the results have shown a number of important declines.
This year’s Big Butterfly Count took place from the 17th of July until the 9th of August and asked people to take 15 minutes to record butterflies or moths that they spotted. As in previous year’s the event was launched by Sir David Attenborough and encouraged the public to get involved with local events, as a family in the back garden or simply during a lunch break in the park.
Results from this year’s count found that the average number of individual butterflies seen per 15minute count had dropped by 9% going from 15 in 2014 to 13 this summer. Overall, abundance was also down with particular declines in Scotland and Northern Ireland were abundance fell 37% and 41% respectively. Butterfly Conservation do note that this summer suffered significantly bad weather especially during the time of this year’s count which may have effected results, although such decline are still worrying.
However, when considering individual species this year’s results found a mixed bag with eleven species increasing from their 2014 count number, seven decreasing and two remaining roughly the same. Holly Blue butterflies were top of the increase list with a 151% gain from last year followed by Silver Y with a 93 % increase and Ringlet butterflies up 72%.
Among the most significant declining species was the Peacock, falling 61% and the Small Tortoiseshell which dropped 57% on 2014 figures. Red Admiral and Speckled Wood also saw drops from last year down by 28% and 25% respectively.
Top of the overall list this summer was Gatekeeper with the highest abundance for the second time in the last five years. Large White took the 2015 second place with Meadow Brown in the number three spot.
Further details on this year’s count including country, habitat or species specific information can be found on The Big Butterfly Count site. An interactive maps of all of this year’s survey locations and data from previous counts is also available online.
The Big Butterfly Count will return again next summer from the 15th of July until the 7th of August 2016
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- Open Access
Crustal deformation associated with the 1998 seismo-volcanic crisis of Iwate Volcano, Northeastern Japan, as observed by a dense GPS network
© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences. 2000
Received: 4 January 2000
Accepted: 4 September 2000
Published: 24 June 2014
Mt. Iwate (2,038 m) is an active volcano located in northeastern Japan. Unrest of the volcano started in September, 1995 with intermediate-depth tremors. The shallow seismicity gradually became active in February, 1998, accompanying the notable crustal deformation observed by a dense GPS network. The pattern of the horizontal displacements is characterized by radially directing outward from the volcano. We estimated the source position by inversion analyses for every two-months period, assuming two models; a point pressure source (Mogi model) and a tensile fault. The comparison of AIC’s for the two models indicates that the latter is proper from February to April, while the former is preferable afterward. The tensile fault was located at about 5 km WSW of the summit and 3 km in depth, then a Mogi source was estimated at the western neighbor of the tensile fault in the successive period and moved westward as far as 10 km W of the summit with shallowing its depth. It should be noted that the seismic area also expanded westward in the same period. This synchronicity suggests that the both phenomena were caused by a movement of magma from the deeper part beneath the summit to the western shallower part. | <urn:uuid:251d5703-578f-4441-b9b8-3e85a1824fbc> | 2.625 | 368 | Truncated | Science & Tech. | 32.131671 | 95,548,888 |
By A. Nelson Wright
Divided into 5 chapters, the ebook starts off by means of giving an creation to the invention of energetic nitrogen, the power content material, and the tools wherein this can be produced. The succeeding half bargains with mild emissions from lively nitrogen procedure. This dialogue contains molecular spectrum of nitrogen, emission from atomic power and condensed energetic nitrogen, emission from molecular species with digital power degrees lower than and above 9.76 eV, and light-emitting platforms of energetic nitrogen.
The subsequent half specializes in theories on energetic nitrogen. The theories mentioned are long-lived Lewis-Rayleigh afterglow and short-lived, lively afterglows. Numerical representations are supplied to check the validity of the theories. finally, the discussions finish with chemical reactions of lively nitrogen. subject matters contained during this half are textual content on recombination of N(4S) atoms; cost constants for reactions possibly caused through direct N(4S) assault; reactions because of excited nitrogen molecular assault; and mechanism for reactions of energetic nitrogen that appear to persuade direct N(4S) assault.
The booklet is a beneficial resource of data for readers attracted to the examine on energetic nitrogen.
Read or Download Active Nitrogen PDF
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Euler's Disk is a scientific educational toy, used to illustrate and study the dynamic system of a spinning disk on a flat surface (such as a spinning coin), and has been the subject of a number of scientific papers. The apparatus is known for a seemingly paradoxical dramatic speed-up in spin rate as the disk loses energy and approaches a stopped condition. This phenomenon is named for Leonhard Euler, who studied it in the 18th century.
Components and use
The commercially available toy consists of a heavy, thick chrome-plated steel disk and a rigid, slightly concave, mirrored base. Included holographic magnetic stickers can be attached to the disk, to enhance the visual effect of "sprolling" or "spolling" (spinning/rolling), but these attachments are strictly decorative. The disk, when spun on a flat surface, exhibits a spinning/rolling motion, slowly progressing through different rates and types of motion before coming to rest—most notably, the precession rate of the disk's axis of symmetry accelerates as the disk spins down. The rigid mirror is used to provide a suitable low-friction surface, with a slight concavity which keeps the spinning disk from "wandering" off a support surface.
An ordinary coin spun on a table, as with any disk spun on a relatively flat surface, exhibits essentially the same type of motion, but is normally more limited in the length of time before stopping. The commercially available Euler’s Disk toy provides a more effective demonstration of the phenomenon than more commonly found items, having an optimized aspect ratio and a precision polished, slightly rounded edge to maximize the spinning/rolling time.
A spinning/rolling disk ultimately comes to rest, and it does so quite abruptly, the final stage of motion being accompanied by a whirring sound of rapidly increasing frequency. As the disk rolls, the point of rolling contact describes a circle that oscillates with a constant angular velocity . If the motion is non-dissipative (frictionless), is constant, and the motion persists forever; this is contrary to observation, since is not constant in real life situations. In fact, the precession rate of the axis of symmetry approaches a finite-time singularity modeled by a power law with exponent approximately −1/3 (depending on specific conditions).
There are two conspicuous dissipative effects: rolling friction when the coin slips along the surface, and air drag from the resistance of air. Experiments show that rolling friction is mainly responsible for the dissipation and behavior—experiments in a vacuum show that the absence of air affects behavior only slightly, while the behavior (precession rate) depends systematically on coefficient of friction. In the limit of small angle (i.e. immediately before the disk stops spinning), air drag (specifically, viscous dissipation) is the dominant factor, but prior to this end stage, rolling friction is the dominant effect.
History of research
In the early 2000s, research was sparked by an article in the April 20, 2000 edition of Nature, where Keith Moffatt showed that viscous dissipation in the thin layer of air between the disk and the table would be sufficient to account for the observed abruptness of the settling process. He also showed that the motion concluded in a finite-time singularity. His first theoretical hypothesis was contradicted by subsequent research, which showed that rolling friction is actually the dominant factor.
Moffatt showed that, as time approaches a particular time (which is mathematically a constant of integration), the viscous dissipation approaches infinity. The singularity that this implies is not realized in practice, because the magnitude of the vertical acceleration cannot exceed the acceleration due to gravity (the disk loses contact with its support surface). Moffatt goes on to show that the theory breaks down at a time before the final settling time , given by:
where is the radius of the disk, is the acceleration due to Earth's gravity, the dynamic viscosity of air, and the mass of the disk. For the commercially available Euler’s Disk toy (see link in "External links" below), is about seconds, at which time the angle between the coin and the surface, , is approximately 0.005 radians and the rolling angular velocity, , is about 500 Hz.
Using the above notation, the total spinning/rolling time is:
where is the initial inclination of the disk, measured in radians. Moffatt also showed that, if , the finite-time singularity in is given by
Moffatt's theoretical work inspired several other workers to experimentally investigate the dissipative mechanism of a spinning/rolling disk, with results that partially contradicted his explanation. These experiments used spinning objects and surfaces of various geometries (disks and rings), with varying coefficients of friction, both in air and in a vacuum, and used instrumentation such as high speed photography to quantify the phenomenon.
In the 30 November 2000 issue of Nature, physicists Van den Engh, Nelson and Roach discuss experiments in which disks were spun in a vacuum. Van den Engh used a rijksdaalder, a Dutch coin, whose magnetic properties allowed it to be spun at a precisely determined rate. They found that slippage between the disk and the surface could account for observations, and the presence or absence of air only slightly affected the disk's behavior. They pointed out that Moffatt's theoretical analysis would predict a very long spin time for a disk in a vacuum, which was not observed.
Moffatt responded with a generalized theory that should allow experimental determination of which dissipation mechanism is dominant, and pointed out that the dominant dissipation mechanism would always be viscous dissipation in the limit of small (i.e., just before the disk settles).
Later work at the University of Guelph by Petrie, Hunt and Gray showed that carrying out the experiments in a vacuum (pressure 0.1 pascal) did not significantly affect the energy dissipation rate. Petrie et al. also showed that the rates were largely unaffected by replacing the disk with a ring shape, and that the no-slip condition was satisfied for angles greater than 10°.
On several occasions during the 2007–2008 Writers Guild of America strike, talk show host Conan O'Brien would spin his wedding ring on his desk, trying to spin the ring for as long as possible. The quest to achieve longer and longer spin times led him to invite MIT professor Peter Fisher onto the show to experiment with the problem. Spinning the ring in a vacuum had no identifiable effect, while a Teflon spinning support surface gave a record time of 51 seconds, corroborating the claim that rolling friction is the primary mechanism for kinetic energy dissipation. Various kinds of rolling friction as primary mechanism for energy dissipation have been studied by Leine who confirmed experimentally that the frictional resistance of the movement of the contact point over the rim of the disk is most likely the primary dissipation mechanism on a time-scale of seconds.
In popular culture
The toy's sound and motion has been captured on both radio and film, for example, in the movies, Snow Flake[disambiguation needed] (flashing toy) and Pearl Harbor (sound for the torpedoes, also played during the Academy Awards show). Euler's Disk was featured on the TV show The Big Bang Theory, season 10, episode 16, which aired February 16, 2017 (MSN.com Euler's Disk vs. Raj).
- List of topics named after Leonhard Euler
- Tippe top – another simple physics toy that exhibits surprising behavior
- "Publications". eulersdisk.com.
- Easwar, K.; Rouyer, F.; Menon, N. (2002). "Speeding to a stop: The finite-time singularity of a spinning disk". Physical Review E. 66 (4): 045102. Bibcode:2002PhRvE..66d5102E. doi:10.1103/PhysRevE.66.045102.
- Moffatt, H. K. (20 April 2000). "Euler's disk and its finite-time singularity". Nature. 404 (6780): 833–834. Bibcode:2000Natur.404..833M. doi:10.1038/35009017. PMID 10786779.
- Van den Engh, Ger; Nelson, Peter; Roach, Jared (30 November 2000). "Analytical dynamics: Numismatic gyrations". Nature. 408 (6812): 540. Bibcode:2000Natur.408..540V. doi:10.1038/35046209.
- Moffatt, H. K. (30 November 2000). "Reply: Numismatic gyrations". Nature. 408 (6812): 540. Bibcode:2000Natur.408..540M. doi:10.1038/35046211.
- Petrie, D.; Hunt, J. L.; Gray, C. G. (2002). "Does the Euler Disk slip during its motion?". American Journal of Physics. 70 (10): 1025–1028. Bibcode:2002AmJPh..70.1025P. doi:10.1119/1.1501117.
- Leine, R.I. (2009). "Experimental and theoretical investigation of the energy dissipation of a rolling disk during its final stage of motion". Archive of Applied Mechanics. 79 (11): 1063–1082. Bibcode:2009AAM....79.1063L. doi:10.1007/s00419-008-0278-6.
- The physics of a spinning coin (April 20, 2000) PhysicsWeb
- Experimental and theoretical investigation of the energy dissipation of a rolling disk during its final stage of motion (December 12, 2008) Arch Appl Mech
- Comment on Moffat’s Disk (March 31, 2002)
- McDonald, Alexander J.; McDonald, Kirk T. (2000). "The Rolling Motion of a Disk on a Horizontal Plane". arXiv: .
- "Euler's Disk". Real World Physics Problems. real-world-physics-problems.com. Retrieved 2014-07-11. Detailed mathematical physics analysis of disk motion | <urn:uuid:55820ad3-2db1-41be-9d4c-5d2f3d41c772> | 3.8125 | 2,133 | Knowledge Article | Science & Tech. | 54.243513 | 95,548,906 |
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Before an earthquake rattles a region, some animals within the vicinity might be able to sense the event just seconds or minutes before it happens.
The earliest reference to unusual animal behavior in response to an impending earthquake dates back to 373 B.C. in Greece, according to the United States Geological Survey (USGS).
Several days before a destructive earthquake hit, creatures such as centipedes, snakes and rats reportedly left their homes to find safe locations, according to the USGS.
Similar accounts have surfaced in the centuries since, including reports of violently moving catfish, restless or barking dogs and panicked bees abandoning their hives, according to the National Geographic.
Scientists can easily explain the cause of unusual animal behavior seconds prior to humans feeling the jolt of an earthquake, the USGS reported.
“Many animals with senses [that are] more keen than humans are able to feel the P wave seconds before the S wave arrives,” said USGS cartographer Diane Garcia.
The USGS defines a P wave, or compressional wave, as a seismic body wave that shakes the ground back and forth in the same direction and the opposite direction of the wave's movement.
An S wave, or shear wave, also shakes the ground back and forth, but does so perpendicular to the wave’s direction of movement.
Rodents and other urban animals are great at sensing subtle changes and reacting to earthquakes before humans do, according to Jordan Foster, a pest technician with Fantastic Pest Control.
“Seismic activity creates stress, which releases charged particles up to the Earth’s surface and into the air,” Foster said. “Those particles transform into ions, which increases the serotonin levels in animals.”
When this occurs, creatures such as rats, weasels, mice and squirrels might behave oddly, including standing frozen in place or acting uneasy.
“This can happen anywhere from a week to just seconds prior to the actual earthquake,” Foster said. Rodents are also able to detect the primary seismic waves far more in advance than people can, he added.
“The primary waves run in the same direction and do not create much of a disturbance, hence why we don’t sense them, but secondary waves run at a right angle to the primary waves, which is the actual earthquake and what humans experience,” Foster said.
Research has also shown that ants might be able to sense an earthquake coming. In advance of earthquakes with a magnitude of 2.0 or greater, ant colonies have been observed stopping their usual activities prior to, during and up to a day after an earthquake, Foster said.
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German researchers found that ahead of an earthquake, red wood ants, which prefer to live along Germany’s active faults, remained awake throughout the night outside their mound, exposed to predators. Such behavior is unusual for ants, as they’re not nocturnal creatures, Foster said.
“It’s unclear how exactly they sense the danger, but the two leading theories are that they can feel the changes of Earth’s magnetic field and sense fluctuations in carbon dioxide levels,” he said.
Most accounts of animals behaving strangely are anecdotal, and consistent, reliable behavior prior to an earthquake as well as a mechanism explaining how it might work still elude scientists, the USGS reported.
Although animals may be able to detect an earthquake seconds before the first tremor, sensing an earthquake days or weeks before it happens is a different story, according to Garcia.
“Much further research needs to be done regarding the possibility of genetic systems having evolved enough to have early warning behaviors for a seismic event,” she said.
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Hot and dry summer weather is expected to persist in the western U.S. this week, perpetuating the wildfire threat and risk of heat-related illness.
In the wake of showers and thunderstorms that will enhance the risk of flash flooding, cooler air will invade the northeastern United States by midweek.
Beryl has redeveloped well off the coast of the mid-Atlantic, but is not expected to have major impacts on land.
While the southeastern U.S. is no stranger to humid, stormy conditions, widespread wet weather will be more disruptive than usual this week.
In the aftermath of the disastrous and historic flooding across western Japan, survivors and recovery crews will continue to face sweltering heat and humidity.
In the United States, more people have died from being left in hot cars than from lightning strikes so far this year.
A mudslide and a freight train derailment led to the closure of U.S. 95 near the Nevada-California state line on Friday.
Two people, a 17-year-old boy and a 30-year-old man, were hospitalized after being bitten by sharks in Fernandina Beach, Florida, on Friday afternoon. | <urn:uuid:8166370e-7be0-4182-a75a-5430f195a31a> | 4.40625 | 1,097 | Truncated | Science & Tech. | 42.089902 | 95,548,916 |
When NASA's Terra satellite passed over the Southern Indian Ocean, the MODIS instrument aboard captured a picture of Tropical Cyclone Adjali that showed it developed a "tail," which is actually band of thunderstorms extending south of the center.
The Moderate Resolution Imaging Spectroradiometer, or MODIS instrument that flies aboard NASA's Terra satellite took a visible picture of Tropical Storm Adjali on Nov. 18 at 05:35 UTC (12:35 a.m. EST).
The MODIS image showed a concentration of strong storms around the center of Adjali's circulation and a band of thunderstorms extending south of the center, resembling a "tail."
On Nov. 18, the Joint Typhoon Warning Center (JTWC) noted that bands of thunderstorms spiraling into the low-level center appeared to be weakening on microwave satellite imagery.
By 0900 UTC (4 a.m. EDT), Adjali's maximum sustained winds were near 60 knots (69/0 mph/111 kph). It was centered near 11.2 south latitude and 70.0 east longitude, about 279 nautical miles (321.1 miles/516.7 km) southwest of Diego Garcia.
Diego Garcia is an island in the central Indian Ocean, and is part of the British Indian Ocean Territory.
Adjali had changed directions since Nov. 17 and was now moving to the southwest at 9 knots (10.3 mph/16.6 kph). Forecasters at JTWC now expect the storm to maintain intensity or slightly weaken over the next day.
After that time, JTWC forecasters expect Adjali to weaken to a depression as it moves through cooler waters.
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
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Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
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Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
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The unique capabilities of a NASA earth-observing satellite have allowed researchers to view the effects of a major earthquake that occurred in 2001 in Northern India near the border of Pakistan.
Lead author Bernard Pinty of the Institute for Environment and Sustainability in the Joint Research Centre of the European Commission, Ispra, Italy, and colleagues from the U.S., France and Germany, used the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASAs Terra satellite to observe the effects of a massive earthquake in the Gujarat province of India.
Considered one of the two most damaging seismic events in Indian recorded history, the Gujarat earthquake struck with a magnitude of 7.7 (Richter scale) on January 26, 2001. About 20,000 people died and another 16 million people were affected. Local residents reported fountains of water and sediments spouting from the Earth following the earthquake.
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Ocean acidification: Coral core reveals dropping pH values in South Pacific
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Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
Sizes and shapes of nuclei with more than 100 protons were so far experimentally inaccessible. Laser spectroscopy is an established technique in measuring fundamental properties of exotic atoms and their nuclei. For the first time, this technique was now extended to precisely measure the optical excitation of atomic levels in the atomic shell of three isotopes of the heavy element nobelium, which contain 102 protons in their nuclei and do not occur naturally. This was reported by an international team lead by scientists from GSI Helmholtzzentrum für Schwerionenforschung.
Nuclei of heavy elements can be produced at minute quantities of a few atoms per second in fusion reactions using powerful particle accelerators. The obtained...
A team headed by the TUM physicists Alexander Holleitner and Reinhard Kienberger has succeeded for the first time in generating ultrashort electric pulses on a chip using metal antennas only a few nanometers in size, then running the signals a few millimeters above the surface and reading them in again a controlled manner. The technology enables the development of new, powerful terahertz components.
Classical electronics allows frequencies up to around 100 gigahertz. Optoelectronics uses electromagnetic phenomena starting at 10 terahertz. This range in...
Russian researchers together with their French colleagues discovered that a genuine feature of superconductors -- quantum Abrikosov vortices of supercurrent -- can also exist in an ordinary nonsuperconducting metal put into contact with a superconductor. The observation of these vortices provides direct evidence of induced quantum coherence. The pioneering experimental observation was supported by a first-ever numerical model that describes the induced vortices in finer detail.
These fundamental results, published in the journal Nature Communications, enable a better understanding and description of the processes occurring at the...
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At a gathering of thousands of scientists at a horseshoe bend in the lower Mississippi River, a few talked about a place far away they have been watching for years.
“The Arctic shows no sign of returning to the reliably frozen state it was a decade ago,” said Jeremy Mathis, an oceanographer with the Pacific Marine Environmental Lab in Seattle.
He was one of four scientists presenting the Arctic Report Card for 2017 at the American Geophysical Union Fall Meeting. More than 20,000 scientists walked through the doors of the Morial Convention Center during second week of December.
Mathis and others, including permafrost expert Vladimir Romanovsky of UAF’s Geophysical Institute, shared many scientists’ 2017 observations of the far North during a press conference.
They reported much of the same news they have since National Oceanic and Atmospheric Administration scientists presented the first Arctic Report Card in 2007: The northern cap of the globe is warming faster than anywhere else on the planet.
In what Mathis called “the darkening of the Arctic,” less sea ice floating on the northern oceans and fewer days of snow on the ground have allowed blue ocean and brown-and-green tundra to receive more heat from the sun. That seems to be playing out in many ways on the northern stage and beyond.
On March 7, 2017, satellites recorded the lowest amount of winter sea ice floating on the northern oceans since scientists have been able to see the view from 500 miles above starting in 1979.
Chunky, resilient ice that has survived several summers made up only 21 percent of the northern sea ice cover. Most ice is younger and thinner.
Though satellites have allowed overall views of sea ice for only a few decades, a researcher on the panel presented evidence that present low-ice conditions have not existed since at least the Middle Ages.
Emily Osborne of the NOAA Arctic Research Program in Maryland looked at lake sediments, ice cores and plugs of seafloor from the Arctic Ocean to find evidence of ancient debris that floated out on sea ice and then sank, and the remains of tiny creatures called diatoms that live in and around sea ice.
She found that there is no period in the last 1,500 years that shows a similar disappearance of northern sea ice.
“It is normal for sea ice to vary from year to year, but when you move forward into the last couple decades, the magnitude (of sea ice loss) is unprecedented,” she said.
Northern sea ice covered a record low amount of Arctic Ocean a decade ago, in September 2007. When scientists at the National Snow and Ice Data Center measured the sea ice in November 2017, they found the third-lowest coverage on record. Though 2007 was perhaps not the tipping point that some scientists thought might lead to ice-free Arctic Ocean summers by now, 10 of the lowest sea ice extent years have occurred in the past 11 years.
Why does less ice matter? Because loss of its mirror-like surface allows the ocean to absorb the sun’s heat.
Some scientists think there is a connection between Romanovsky holding up his phone to show them a well-above average 24 degrees F temperature at his home in Fairbanks and a New Orleans cold snap a few days ago. Snow fell here in this city at 30 degrees north latitude.
“Loss of ice in the Chukchi Sea is reinforcing a very wavy jet stream, which might account for the winds and fires in California and cold in the central and eastern U.S. right now,” said oceanographer Jim Overland of the Pacific Marine Environmental Laboratory.
He explained that the current record low sea ice coverage in the Chukchi Sea off the northwest coast of Alaska has provided a lot more heat to the atmosphere.
Conditions in the Arctic have always affected weather at lower latitudes, Overland said after the press conference, but the extra northern heat is helping maintain large-scale patterns that endure longer.
“The jet stream is the door between the Arctic and weather at mid-latitudes,” he said.
That door seems to be open more often now than it has been in the past, he said, allowing warmer Arctic air to flow southward and more often affect weather down here.
Since the late 1970s, the University of Alaska Fairbanks’ Geophysical Institute has provided this column free in cooperation with the UAF research community. Ned Rozell is a science writer for the Geophysical Institute.
Source: University of Alaska Fairbanks
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Researchers confirm second layer of information in our DNA
THE HANS INDIA |
Jun 10,2016 , 11:03 PM IST
London: Confirming a long-standing hypothesis, scientists from the Netherlands' Leiden University have shown that the genetic information in the DNA not only determines who we are, but also the DNA mechanics.
Since the mid-198080s it has been hypothesised that there is a second layer of information on top of the genetic code: DNA’s mechanical properties.
Each of our cells contains two meters of DNA molecules, so these molecules need to be wrapped up tightly to fit inside a single cell. The way in which DNA is folded, determines how the letters are read out, and therefore which proteins are actually made. In each organ, only relevant parts of the genetic information are read, based on how the DNA is folded.
The theory goes that mechanical cues within the DNA structures determine how DNA prefers to fold. In a study published in the journal PLoS One, Leiden physicist Helmut Schiessel and his research group provided strong evidence that this second layer of information indeed exists.
With their computer code they simulated the folding of DNA strands with randomly assigned mechanical cues. It turns out that these cues indeed determine how the DNA molecule is folded into so-called nucleosomes.
Schiessel found correlations between the mechanics and the actual folding structure in the genome of two organisms ? baker’s yeast and fission yeast.
With this finding we know that evolutionary changes in DNA ? mutations? can have two very different effects.The letter sequence encoding for a specific protein can change or the mechanics of the DNA structure can change, resulting in a different packaging and accessibility of the DNA and therefore a different frequency of production of that protein.
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Superconducting Qubits and Circuits
by Steven M. Girvin
Publisher: Yale University 2011
Number of pages: 132
These lectures are devoted to understanding the basic components of quantum machines that can be constructed from superconducting electrical circuits. These circuits can be used to create resonators which store individual microwave photons and to create superconducting quantum bits.
Download or read it online for free here:
by Clare Hewitt-Horsman - arXiv
This paper introduces one interpretation of quantum mechanics, a modern 'many-worlds' theory, from the perspective of quantum computation. Reasons for seeking to interpret quantum mechanics are discussed, then the specific theory is introduced.
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A short review of ideas in quantum information theory. Quantum mechanics is presented together with some useful tools for quantum mechanics of open systems. The treatment is pedagogical and suitable for beginning graduates in the field.
by Bei Zeng, et al. - Springer
The draft version of a textbook, introducing the quantum information science viewpoints on condensed matter physics to graduate students. We keep the writing in a self-consistent way, requiring minimum background in quantum information science.
by David Mermin - Cambridge University Press
A concise introduction to quantum computation, developing the basic elements of this branch of computational theory without assuming any background in physics. It begins with an introduction to the quantum theory from a computer-science perspective. | <urn:uuid:f14fb2e2-03f8-4d38-a7b7-946630b492a1> | 2.734375 | 298 | Content Listing | Science & Tech. | 23.870354 | 95,548,965 |
Humans and animals are able to perceive even the slightest vibration and touch of the skin. Mechanosensitive ion channels play a crucial role in the mediation of these sensations.
Ion channels are pores in the cell membrane which are highly responsive to external signals. Mechanosensitive ion channels open at the slightest vibration and allow ions (electrically charged particles), to cross the cell membrane, which causes an electrical current until the channel closes again.
Until now it was unclear how the ion channels were opened. Dr. Jing Hu and Professor Gary Lewin of the Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch, Germany, have now discovered the presence of a protein filament that causes the ion channels to open and shut like a tethered gate (EMBO Journal,Vol. 29, No. 4, pp 855-867; doi: 10.1038/emboj.2009.398)*.
In their study, the researchers showed that the opening and closing of ion channels literally "hangs by a thread". This protein thread or filament, as Dr. Hu and Professor Lewin demonstrated, is synthesized by the mechanosensitive endings of cutaneous neurons and is probably an integral part of the mechanosensitive mechanism.
The thread is firmly tethered in the extracellular matrix (ECM), the connective protein "glue" that helps to hold cells together. However, the filament is located so close to the mechanosensitive ion channels that it can probably directly open them. The filaments were found to be 100 nanometers (nm) long (1 nanometer is equivalent to one billionth of a meter) and may link the ion channels of the cell membrane to the ECM at mechanosensitive sensory endings of the skin in mice.
The researchers demonstrated both with neuronal cultures and experiments using the isolated skin with receptors attached that the opening of mechanosensitive ion channels upon slight touch requires the 100nm protein filament. The stretching of sensory membranes by small mechanical stimuli does not appear to play any significant role in touch receptors.
When the researchers cleaved the filament with specific enzymes, thus cutting the link between the sensory ending and the extracellular matrix (ECM), the neurons were rendered completely insensitive to mechanical stimulation and touch. However, if the researchers waited twelve hours the filaments were again synthesized by the sensory cells and they became mechanosensitive once more.
"This means that touch can be perceived only when the protein filament is present. The filament renders the mechanosensitive ion channel highly sensitive to force and may even directly participate in opening and closing the channel " Professor Lewin explained.
However, this does not apply to the perception of mechanical pain. "Pain receptors" he emphasized, "are not dependent on this filament." According to the neurobiologists, the protein filaments may in the future be of great interest to medical research. Advancements in this area could help people whose sense of touch is impaired due to old age, improving their general well-being and mobility. There are also common syndromes where there is oversensitivity to touch, in the case of neuropathic pain where the slightest touch of feather may be perceived as painful, again accessing the tether may help in alleviating the symptoms.*Evidence for a protein tether involved in somatic touch
Barbara Bachtler | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
19.07.2018 | Earth Sciences
19.07.2018 | Power and Electrical Engineering
19.07.2018 | Materials Sciences | <urn:uuid:41ad431d-7ff0-44fc-8af2-08806698d2d5> | 3.03125 | 1,330 | Content Listing | Science & Tech. | 37.403879 | 95,548,978 |
As residents in the Caribbean try to piece together their lives after being battered by two powerful hurricanes in a fortnight, scientists are working to find out if storms Irma and Maria are signs of what may come as the climate changes.
The link between climate change and tropical hurricanes is a slippery one. While scientists broadly understand the natural mechanics that drive these cyclonic storms, accurately predicting what may happen on a warming planet is far harder.
Some climate models — run on supercomputers that simulate the earth’s physical systems to predict changes in the future — reveal a future where there may be fewer hurricanes and typhoons, but those that do occur could be more powerful. Other research suggests the frequency will not change while there are studies that indicate tropical cyclones will become more common and more intense.
For nations in the path of destructive hurricanes, this uncertainty presents serious dilemmas for how to best prepare for the future. Should they invest billions in storm-proof infrastructure to protect their citizens, or abandon the most vulnerable communities to fate? Will more damage be caused by flooding or high-speed winds? Are their major cities likely to be at greater risk?
In the wake of Hurricane Irma, the most powerful Atlantic Ocean storm in recorded history, and Hurricane Maria, another storm which is ranked as the most powerful Category 5, many are turning to scientists to give them answers.
One major EU-funded project could help to provide them. The PRIMAVERA project is producing a new generation of high-resolution climate models that will examine how the oceans and atmosphere will respond over the next 30 years.
It will combine the results of seven different models which will be run side-by-side, all attempting to answer the same questions. One of these will be how global warming is likely to alter the relationship between the Atlantic Ocean and storms that form over it.
‘If we see a rise in sea surface temperatures in the Mediterranean, this may favour the formation of tropical-like cyclones.’
Dr Emmanouil Flaounas, National Observatory of Athens, Greece
‘The climate models we are developing have a much higher resolution than the ones we are currently using,’ said Louis-Philippe Caron, a research scientist at the Barcelona Supercomputing Center in Spain, who is taking part in PRIMAVERA. ‘This next generation of models should have the sort of resolution where we can simulate the structure of the storms at a more realistic size and intensity.’
Hurricanes form due to a complex interplay between the ocean and the atmosphere.
Current climate models are able to simulate the effects of the ocean and atmosphere at a resolution typically between 50 and 100 kilometres, but at this sort of level it is hard to replicate many of the conditions that determine the size and intensity of hurricanes.
Another problem is comparing current models — they tend to use different data experimental approaches and different analysis approaches, which makes them hard to compare.
In PRIMAVERA, scientists are attempting to develop seven next-generation climate models that can replicate conditions in both the ocean and the atmosphere with some achieving a resolution of 15 kilometres. The models will simulate the observations over a 100-year period between 1950 and 2050, gathering atmospheric data for every three hour period.
‘The simulations we produce will be a lot more realistic and we will be able to compare them with the real observations we have from the recent past,’ said Caron. A single simulation run on the EU's European Commission-earth model being developed at the Barcelona Supercomputing Center as part of the PRIMAVERA project, will produce around 150 terabytes of data.
‘The amount of data we will be producing is vast,’ added Caron. ‘But as we will have many high-resolution models, all doing the same experiment and being analysed together, if we see them producing the same results, we can start answering some of the big questions about hurricanes. It is why this project is quite exciting.’
Those questions include how many storms might occur as the climate changes, but also the impact climate change will have on the destructiveness of storms, their wind intensity and the rainfall they produce.
The models could also help to reveal what impact hurricanes will have on Europe. Some hurricanes can travel North across the Atlantic, turning into ex-tropical cyclones that then dump large amounts of rain over Europe, causing severe flooding.
But many parts of Europe are often hit by a different type of cyclone that forms over the Mediterranean Sea and could be affected by climate change.
‘The Mediterranean is one of the hotspots for the formation of cyclones in the world,’ said Dr Emmanouil Flaounas, a meteorologist at the National Observatory of Athens in Greece who is conducting research on these storms in an EU-funded project called ExMeCy. ‘It is a very small region, but has a lot of cyclones.’
Although not as powerful as tropical cyclones, these storms can bring heavy rainfall and high winds, causing billions of Euros in damage in the countries surrounding the Mediterranean.
Dr Flaounas and his colleagues have already shown that in an 11-year period, 500 intense cyclones are responsible for up to 40 % of the total rainfall in the Mediterranean.
‘About once to three times per year, these cyclones may reach comparable intensity to a Category 1 hurricane,’ explained Dr Flaounas. ‘They can cause a lot of damage and flooding.’
These extremely powerful storms are known in the scientific literature as ‘medicanes’ — a portmanteau of the words ‘Mediterranean’ and ‘hurricanes’.
Unlike tropical cyclones, however, medicanes tend to form in the winter and typically only deliver rain for a day or two.
But Dr Flaounas’ research is also finding that not all medicanes are created equal. While some of the most powerful bring intense rainfall, there are other intense medicanes that generate little rain at all.
‘Some very strong cyclones might present very weak rainfall during their mature stage,’ said Dr Flaounas. ‘It appears to be quite unique to the Mediterranean.’
He has highlighted two different atmospheric processes appear to play a role in determining whether these storms will bring heavy rain or not.
Those with intense rainfall are powered by convection of water vapour from the ocean, much like tropical hurricanes, but also have layers of air known as warm conveyor belts, which are typically seen in the frontal weather systems that form off the west coast of the UK.
The drier storms do not show many signs of either of these atmospheric processes.
‘Knowing more about the detail of these processes and the impact they have on rainfall can help us to understand what will happen in the future as the climate changes,’ said Dr Flaounas.
There is some concern that changes in the climate may already be changing the behaviour of Mediterranean storms.
In November 2011 the south of France was hit by a medicane so large and powerful it was tracked by the US National Oceanic and Atmospheric Administration. Other recent powerful storms in November 2014 and October 2016 also formed a huge spirals more characteristic of tropical storms.
‘If we see a rise in sea surface temperatures in the Mediterranean, this may favour the formation of tropical-like cyclones,’ said Dr Flaounas. ‘At the moment there is too much uncertainty to know. But if we can understand what causes differences in the rainfall in Mediterranean storms, it can help us anticipate what will happen in the future.
‘This could help ensure the right mitigation plans are put in place,’ he said.
In the warm, humid regions of the tropics, ocean surface temperatures can rise above 27 degrees celsius, causing water vapour to rise off the ocean surface into the air.
This evaporation carries heat into the atmosphere, where the water vapour condenses to forms storm clouds, releasing energy into the surrounding air. This drives convection currents in the atmosphere, producing winds, which form into a distinctive swirling vortex due to the rotation of the earth.
Tropical cyclones become named storms once wind speeds exceed 39 miles per hour (62 kilometres per hour). To be classified as a hurricane, typhoon or cyclone - the name depends where in the world the storm occurs - wind speeds must exceed 74 miles per hour (119 kilometres per hour).
As the hurricane pulls more heat from the ocean surface it can grow rapidly, but this can also drag up colder water from the depths, which can in turn slow the cyclone down.
When a cyclone hits land, it starts to weaken as it is no longer able to draw the heat that powers it from the ocean surface.
In the Atlantic Basin there are anywhere between four and 28 named tropical storms in any given year. This year there have already been 14 named storms with predictions that there could be a further five before the hurricane season ends.
Greenhouse gas emissions have risen significantly since pre-industrial times, while fossil fuel use and industrial processes increased by 126 % between 1970 and 2013.
The EU has set targets for reducing its greenhouse gas emissions by 20 % by 2020 compared to 1990 levels. This is part of its trio of goals known as the 20-20-20 targets, in which the EU also commits to sourcing 20 % of EU energy from renewables and achieving a 20 % improvement in energy inefficiency.
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A new way to farm indoors using different wavelengths of light could boost the taste of fruits, salads and herbs, while also increasing food supply and nutritional value.
Non-surgical ways of detecting endometriosis, such as blood tests, could reduce the time taken for a diagnosis, and researchers hope it will have a significant impact on the quality of life of women who live with the complex and painful condition.
Requiring drones to identify and authorise themselves before they can fly, which could be achieved by fitting them with SIM cards, could help to protect people's privacy by providing an effective way to register both users and machines, according to air traffic management expert Robin Garrity. He has been working on the U-space plan, which sets out a vision for how drones can be integrated into airspace, particularly in urban environments. It is part of work being conducted by the SESAR Joint Undertaking, a public-private partnership that coordinates EU research activities in air traffic management.
Complex and painful disease has been historically overlooked, researchers say.
Robin Garrity says that registration, identification and geofencing will increase security.
Chemical switches on DNA could explain how the environment may influence the traits we pass on, according to Prof. Thomas Carell. | <urn:uuid:097bbb82-735a-488f-b744-7af8c113b774> | 3.578125 | 2,235 | News Article | Science & Tech. | 34.846052 | 95,548,991 |
Professors Timm Maier and Sebastian Hiller from the Biozentrum of the University of Basel now demonstrate how these transporter proteins are integrated into the outer membrane.
Proposed mechanism how bacteria integrate autotransporter into their outer membrane. Left: protein structure of TamA, right: TamA with autotransporters (orange).
Using x-ray structural analysis they reveal the structure-function relationship of the protein TamA, which plays an important role in the assembly of transport proteins in the bacterial outer membrane. Their findings have been published recently in the renowned scientific journal «Nature Structural and Molecular Biology».
Shuttling proteins from inside the cell to the outside environment is a complex task for Gram-negative bacteria, which are not only surrounded by an inner membrane, but also by an outer membrane barrier for protection against adverse environmental conditions.
The bacteria however, can overcome this additional barrier by inserting special transport proteins into the protective outer membrane. In a joint project, Maier and Hiller, both Professors of Structural Biology at the Biozentrum of the University of Basel, provide mechanistic insights into this key process.
The structure of the assembly protein TamA explains its function
An important option for channeling protein domains across the outer membrane are so-called autotransporters. These membrane proteins form a barrel-like structure with a central pore, but they cannot autonomously transport their “passenger domain” across the outer membrane.
Specific assembly proteins are required for the folding and integration of autotransporters into the outer membrane. Employing x-ray crystallography, the authors of the study decoded the atomic structure of the autotransporter assembly protein TamA of the intestinal bacterium Escherichia Coli.
“The protein TamA”, explains Fabian Gruss, first author and recipient of a Werner-Siemens PhD fellowship, “also forms a barrel with a pore. The pore is closed to the outside by a lid but a particular kink in the barrel wall provides a gate for autotransporter substrates.” When an unfolded autotransporter is delivered, TamA hooks onto one end of the substrate polypeptide chain and integrates it step by step via the gate into its own barrel structure.
The TamA barrel is thus expanded; the pore widens and opens such that passenger substrates traverse to the exterior. The assembly process ends when TamA releases the autotransporter into the surrounding membrane. “The autotransporter insertion mechanism was previously completely enigmatic – for the first time, knowing the structure of TamA, we can now picture how assembly and translocation could function.”
Assembly process important for infections
Many pathogens, such as the diarrhea causing Yersinia, Salmonella or the Cholera pathogen, belong to the group of Gram-negative bacteria. With the help of the autotransporter, they release toxins or adhesive proteins to infect their host cells. In their study, Maier and Hiller provide completely new findings about membrane insertion of autotransporters as well as the translocation of their cargo.Original Citation
http://www.nature.com/nsmb/journal/vaop/ncurrent/abs/nsmb.2689.html - Abstract
Christoph Dieffenbacher | Universität Basel
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences | <urn:uuid:c893b5a4-1f1d-4328-8723-430604749e5d> | 2.640625 | 1,286 | Content Listing | Science & Tech. | 30.343041 | 95,548,994 |
India’s temperature rose by 0.60 degree Celsius over last 110 years: govt
Minister says in line with rising temperatures across the globe, all India mean temperatures have risen nearly 0.60 degree Celsius over the last 110 years
New Delhi: India’s temperature has risen by nearly 0.60 degree Celsius over the last 110 years and extreme events like heat waves have increased in the last 30 years, the Rajya Sabha was informed on Monday.
“According to the Indian Meteorological Department (IMD), in line with rising temperatures across the globe, all India mean temperatures have risen nearly 0.60 degree Celsius over the last 110 years. Further IMD studies have highlighted that extreme events like heat waves have risen in the last 30 years.
“Similarly, trends in extreme rainfall events in last century showed significant positive trend over the west coast and northwestern parts of peninsula,” environment minister Anil Madhav Dave said in a written reply.
He said as per the fifth Assessment Report (AR5) of Intergovernmental Panel on Climate Change (IPCC) published in 2014, globally averaged combined land and ocean surface temperature has risen by 0.85 degree Celsius over the period 1880 to 2012.
Many extreme weather and climate events like heat waves, heavy precipitation and tropical cyclones have been observed since about 1950, he said. The government has launched the National Action Plan on Climate Change (NAPCC) in June, 2008 to deal with climate change and related issues.
NAPCC comprises of eight missions in specific areas of solar energy, enhanced energy efficiency, habitat, water, sustaining Himalayan ecosystems, forestry, agriculture and strategic knowledge for climate change.
These missions address the issues relating to mitigation of greenhouse gases and adaptation to the adverse impacts of climate change on environment, forests, habitat, water resources and agriculture, he said.
“All states and UTs have also been requested to prepare State Action Plan on Climate Change (SAPCC) in line with the objectives of the NAPCC highlighting state-specific issues relating to climate change. So far, 32 states and UTs have prepared their SAPCC,” the minister said.
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USA has the world's most extreme weather
New Discovery Channel series will explore how North America's wildlife adapts to the wildest weather on the planet.
North America — and the USA in particular — has the world's wildest weather extremes: No other part of the planet can boast its ferocious weather stew of hurricanes, tornadoes, droughts, floods, wildfires, blizzards, heat waves and cold snaps.
"You'd be hard-pressed to find another patch of land on Earth the size of the USA that boasts such a variety of such intensely extreme weather inside its borders," says meteorologist and author Robert Henson of Boulder, Colo.
"We get more high-impact weather than any other country on the planet," agrees Sean Potter, a meteorologist and weather historian in New York City.
This wild, varied and extreme weather provides a dramatic backdrop for a new, seven-part Discovery Channel series, North America, which premieres Sunday at 9 p.m. ET/PT. According to Discovery, the series "will reveal the intimate stories of animals struggling to survive in unforgiving weather and rugged terrain."
Filmmakers say that weather plays a huge part in the series. "North America has some of the most extreme weather on the planet — something I'm sure will resonate with a lot of Americans," says series producer Huw Cordey of Discovery.
Our wild weather has always fascinated us, and was a shock to the early pioneers. "Europeans who settled America from east to west were progressively amazed by the spectrum of conditions they encountered," wrote Henson in his book The Rough Guide to Weather.
What makes it so wild?
"The U.S. is uniquely situated in the mid-latitudes — about halfway between the equator and the North Pole — and between two oceans," Potter notes. "The contrast of cold, dry, Arctic air from Canada and warm, moist, tropical air from the Gulf of Mexico, Pacific and Atlantic help fuel the massive storms that move across the country year-round, bringing everything from blizzards to heavy rain and thunderstorms, depending on the time of year," he says.
Tornadoes, such as the ones that slammed Texas on Wednesday, are nearly a uniquely American phenomenon. Each year, "the U.S. experiences about 80% to 90% of all of the tornadoes that occur across the world," says Randy Cerveny, a professor of geography at Arizona State University.
"The U.S. averages more than 10,000 severe thunderstorm events per year, with more than 1,000 tornadoes," Potter says. "By comparison, China, which is slightly larger in size, sees around the same number of severe thunderstorms, but fewer than 10 tornadoes per year."
Also, as for wild temperature extremes, the fact that North America has no east-west mountain range means there's nothing to stop the cold winds from the north meeting the warm weather from the south, says Discovery's Cordey.
"The mountains allow the influx of very cold air from Canada and even Siberia to spill down into the center of the country and for massive humidity and hurricanes to come up from the south, such as the Gulf of Mexico," Cerveny says.
These weather phenomena shape the landscapes, which in turn shape the wildlife, as the Discovery series will showcase. "The deserts depend on the annual monsoons — pretty much the only proper rain for the year — and the animals have to adapt accordingly," Cordey says. "The Plains are racked by extreme weather changes — very cold winters, where the ground can be thick with snow, to blistering hot summers."
Many animals can't cope with these massive seasonal shifts and migrate (or hibernate) in the winter, he says. "Indeed, North America has some of the greatest migration spectacles on the planet. No coincidence, as this is a direct result of the weather changes."
Cerveny agrees: "Without question, wildlife adapts to climate so we find very diverse and — because of the incredible extremes in climate — adaptable wildlife in this country.
"From the bison of the Great Plains (adjusting to the low rainfall and grasslands) to the crocodiles of the Florida Everglades (adapting to the wet and marshy conditions of Florida) and the beavers of northern states (acclimating to the colder, and more damp, conditions of the northern states), the wildlife of the U.S. has clearly adapted to the specific conditions found across the country," he continues.
"In some cases, the incredible diversity of climate, even within short geographic distances, has led to actual differentiation of species. In the Grand Canyon, for instance, there are two distinct species of squirrels — one on the north side of the canyon and another on the south side," Cerveny concludes.
"An extravagant array of wildlife learned how to adapt to the weather between Atlantic and Pacific long before this land became the USA," Henson says. "If a species is well-suited to the mountains, Plains or coastline, it can survive even if some members are lost to a harsh winter or a brutal storm."
"What remains to be seen," Henson says, "is how the USA's wildlife will adapt not to a single weather event but to a sustained change in climate, as our warming trend continues and both drought and heavy rains become more intense." | <urn:uuid:def78059-6eb0-4ac7-a17b-05be52d457de> | 2.828125 | 1,138 | Truncated | Science & Tech. | 44.526337 | 95,549,024 |
Princeton Physicist Points Out The Obvious: Climate Models ‘Don’t Work’
Princeton University physicist William Happer is not a fan of models used to predict future manmade global warming, and stars in a new educational video laying out the reasons he believes climate models are faulty.
“And I know they don’t work. They haven’t worked in the past. They don’t work now. And it’s hard to imagine when, if ever, they’ll work in the foreseeable future,” Happer said in a video produced by PragerU.
In the video, Happer argues that even supercomputers used to predict the weather and forecast future global warming aren’t strong enough to capture the complexity of Earth’s atmosphere, including cloud cover and natural ocean cycles.
“That’s why, over the last 30 years, one climate prediction after another — based on computer models — has been wrong,” Happer said in the video. “They’re wrong because even the most powerful computers can’t solve all the equations needed to accurately describe climate.”
Scientists have increasingly been grappling with reconciling the difference between global climate model projections and real-world temperatures. Scientists skeptical of catastrophic manmade warming often point out that models overestimate warming from greenhouse gases.
Cato Institute climate scientists Patrick Michaels and Chip Knappenberger found that real-world warming has been on the low end of model predictions for the last six decades, and a more recent study published in the journal Nature Geoscience found a similar trend.
“We haven’t seen that rapid acceleration in warming after 2000 that we see in the models. We haven’t seen that in the observations,” Myles Allen, a geosystem scientist at the University of Oxford, told The Times in 2017.
But other scientists have been critical of claims that models overestimate warming. University of California, Berkeley climate scientist Zeke Hausfather said models only predict about 8 percent more warming than what’s actually happened.
A quick reminder that, reports in British tabloids notwithstanding, climate model projections agree quite well with observed temperatures. pic.twitter.com/7NxGUlBkFu
— Zeke Hausfather (@hausfath) September 20, 2017
But then again, the strong El Nino warming event that peaked in 2016 did much to bring global average surface temperature “back in line” with climate model predictions.
Satellite temperature readings of the bulk atmosphere also show a mismatch between model predictions and observations. Climate scientist John Christy’s research has shown that models show 2.5 times more warming than has been observed.
“Instead of admitting this, some climate scientists replace the highly complex equations that describe the real-world climate with highly simplified ones—their computer models,” Happer said.
“Discarding the unmanageable details, modelers ‘tune’ their simplified equations with lots of adjustable inputs—numbers that can be changed to produce whatever result the modelers want,” Happer said. “So, if they want to show that the earth’s temperature at the end of the century will be two degrees centigrade higher than it is now, they put in the numbers that produce that result … That’s not science. That’s science fiction.”
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Regional Climate Changes: Where and How?
Global change fascinates scientists and authorities, and predictions for climatic and environmental impacts are rapidly advancing. Large modelling exercises, as reported by IPCC (2001) and Siedler et al. (2000), can answer many questions on climate change. Local consequences can be predicted by studying records on rainfall, river runoff and temperature. Good international cooperation has made these accessible from international databanks (NOAA 2002; BAFG 2002; NCEP 1996) through the internet.
KeywordsRiver Runoff Regional Climate Change Rainfall Trend Rainfall Change Minimum Rainfall
Unable to display preview. Download preview PDF.
- BAFG (2002) Global Runoff Data Center. Koblenz, Germany (http://www.bafg.de/grdc.htm )
- Duursma EK (2002) Historical rainfall, river flow and temperature profile data and trends; consequences for water resources. Heineken NV, Amsterdam, 32 pp + CD-ROMGoogle Scholar
- IPCC (2001) Climate change 2001, the scientific basis. Working group I, WMO-UNEP, Cambridge Univ Press, CambridgeGoogle Scholar
- NCEP (1996) The NCEP/NCAR 40-year reanalysis project. Bull Am Meteor Soc 77:437-471 (http://ingriclidgo.columbia.edu/SOURCES/NOAALNCEP-NCAR/)
- NOAA (2002) Rainfall Databank. v2.prcp.z and v2.prcp_adj.z. National Oceanographic and Atmospheric Agency, Washington ( http://www.ncdc.noaa.gov )
- Semenov V, Bengtsson L (2000) Secular trends in daily precipitation characteristics: greenhouse gas simulation with a coupled AOGCM. Max Planck Institut für Meteorologie, Hamburg (Report 131 )Google Scholar
- Siedler G, Church J, Gould J (2000) Ocean circulation and climate. Academic Press, San DiegoGoogle Scholar | <urn:uuid:9f5efe0b-39db-4f5b-8e5c-fb6073e1bcad> | 3.015625 | 433 | Truncated | Science & Tech. | 49.855769 | 95,549,108 |
A new US and Australian study – including research from The University of Queensland and the Australian Research Council Centre of Excellence in Coral Reef Studies –compared early British charts to modern coral habitat maps to understand changes to reef environments.
UQ’s Professor John Pandolfi said the study used information from surprisingly accurate 18th century nautical charts and satellite data to understand coral loss over more than two centuries in the Florida Keys. “We found that some reefs had completely disappeared,” Professor Pandolfi said. The study was led by Loren McClenachan, Assistant Professor at Colby College, in Waterville, Maine, USA.
Professor McClenachan said more than half of the coral reef habitat mapped in the 1770s was no longer there. In some areas, particularly near land, coral loss was closer to 90 per cent.
“We found near the shore, entire sections of reef are gone, but in contrast, most coral mapped further from land is still coral reef habitat today,” she said.
This estimate of change over centuries added to modern observations of recent loss of living corals.
The marine scientists measured the loss of coral reef habitats across a large geographic area, while most studies look more closely at the loss of living coral from smaller sections of the reef.
“We found that reef used to exist in areas that today are not even classified as reef habitat anymore,” Professor Pandolfi said.
“When you add this to the 75 per cent loss of living coral in the Keys at that finer scale, the magnitude of change is much greater than anyone thought.”
This work was undertaken while Professor McClenachan was a visiting researcher in Professor Pandolfi’s lab at UQ’s School of Biological Sciences in Brisbane, Australia, while on sabbatical from Colby College.
The research revealed the precision of the early maps. Postdoctoral researcher at the Bigelow Laboratory for Ocean Sciences in East Boothbay, Maine Dr Benjamin Neal said the early chart makers represented the “Silicon Valley of their time”. “They had the best technology and they used it to create new information that conferred a lot of power,” Dr. Neal said.
“The maps were essential to expansion of the British Empire, and luckily for us, they also included a lot of useful ecological information.”
Professor McClenachan said the findings had important conservation implications and pointed to a shifted spatial baseline.
“We tend to focus on known areas where we can measure change. That makes sense. Why would you look for coral where you never knew it was?” she said.
The authors said when large-scale changes like this were overlooked, scientists could lose sight of past abundance, lowering expectations for conservation and recovery.
The study, which also involved authors from Columbia University, National Museum of Natural History, Smithsonian Institution and the University of California San Diego, all in the U.S., is published in Science Advances (doi: 10.1126/sciadv.1603155)
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The finding, described in the Sept. 23, 2012, issue of the journal Nature Chemical Biology, arose from an intriguing notion that some of the genetic and chemical changes in cancer tumors might be harnessed for beneficial uses.
"In our lab, we study genetic changes that cause healthy tissues to go bad and grow into tumors. The goal of this research is to understand how the tumors develop in order to design better treatments," said Zachary J. Reitman, Ph.D., an associate in research at Duke and lead author of the study. "As it turns out, a bit of information we learned in that process paves the way for a better method to produce nylon."
Nylon is a ubiquitous material, used in carpeting, upholstery, auto parts, apparel and other products. A key component for its production is adipic acid, which is one of the most widely used chemicals in the world. Currently, adipic acid is produced from fossil fuel, and the pollution released from the refinement process is a leading contributor to global warming.
Reitman said he and colleagues delved into the adipic acid problem based on similarities between cancer research techniques and biochemical engineering. Both fields rely on enzymes, which are molecules that convert one small chemical to another. Enzymes play a major role in both healthy tissues and in tumors, but they are also used to convert organic matter into synthetic materials such as adipic acid.
One of the most promising approaches being studied today for environmentally friendly adipic acid production uses a series of enzymes as an assembly line to convert cheap sugars into adipic acid. However, one critical enzyme in the series, called a 2-hydroxyadipate dehydrogenase, has never been produced, leaving a missing link in the assembly line.
This is where the cancer research comes in. In 2008 and 2009, Duke researchers, including Hai Yan, M.D., PhD., identified a genetic mutation in glioblastomas and other brain tumors that alters the function of an enzyme known as an isocitrate dehydrogenase.
Reitman and colleagues had a hunch that the genetic mutation seen in cancer might trigger a similar functional change to a closely related enzyme found in yeast and bacteria (homoisocitrate dehydrogenase), which would create the elusive 2-hydroxyadipate dehydrogenase necessary for "green" adipic acid production.
They were right. The functional mutation observed in cancer could be constructively applied to other closely related enzymes, creating a beneficial outcome – in this case the missing link that could enable adipic acid production from cheap sugars. The next step will be to scale up the overall adipic acid production process, which remains a considerable undertaking.
"It's exciting that sequencing cancer genomes can help us to discover new enzyme activities," Reitman said. "Even genetic changes that occur in only a few patients could reveal useful new enzyme functions that were not obvious before."
Yan, a professor in the Department of Pathology and senior author of the study, said the research demonstrates how an investment in medical research can be applied broadly to solve other significant issues of the day.
"This is the result of a cancer researcher thinking outside the box to produce a new enzyme and create a precursor for nylon production," Yan said. "Not only is this discovery exciting, it reaffirms the commitment we should be making to science and to encouraging young people to pursue science."
In addition to Reitman and Yan, study authors include Bryan D. Choi, Ivan Spasojevic, Darell D. Bigner and John H. Sampson.
The work was supported with funds from the National Institutes of Health (R01 CA1403160). The authors are listed on a patent that is pending related to the mutated enzymes.
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
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What, you say? There are more than one Moon? Huh? To the uninitiated this may sound like a bunch of malarkey but I assure you, this is as real as it gets.
We all know and love the moon. We're so assured that we only have one that we don't even give it a specific name. It's just The Moon. But the moon is not the Earth's only natural satellite. Here's what you need to know about 3753 Cruithne and what its weird orbit reveals about the solar system.
As recently as 1997, we discovered that another body, 3753 Cruithne, is a quasi-orbital satellite of Earth.
This simply means that Cruithne doesn't loop around the Earth in a nice ellipse in the same way as the moon, or indeed the artificial satellites we loft into orbit. Instead, Cruithne scuttles around the inner solar system in what's called a "horseshoe" orbit.
Cruithne's Weird Orbit
To help understand why it's called a horseshoe orbit, let's imagine we're looking down at the solar system, rotating at the same rate as the Earth goes round the sun. From our viewpoint, the Earth looks stationary. A body on a simple horseshoe orbit around the Earth moves toward it, then turns round and moves away. Once it's moved so far away it's approaching Earth from the other side, it turns around and moves away again.
Cruithne from a Stationary Earth Position
Horseshoe orbits are actually quite common for moons in the solar system. Saturn has a couple of moons in this configuration, for instance.
What's unique about Cruithne is how it wobbles and sways along its horseshoe. If you look at Cruithne's motion in the solar system, it makes a messy ring around Earth's orbit, swinging so wide that it comes into the neighborhood of both Venus and Mars. Cruithne orbits the sun about once a year, but it takes nearly 800 years to complete this messy ring shape around the Earth's orbit.
Cruithne Close Up
So Cruithne is our second moon. What's it like there? Well, we don't really know. It's only about five kilometers across, which is not dissimilar to the dimensions of the comet 67P/Churyumov-Gerasimenko, which is currently playing host to the Rosetta orbiter and the Philae lander.
The surface gravity of 67P is very weak – walking at a spirited pace is probably enough to send you strolling into the wider cosmos. This is why it was so crucial that Philae was able to use its harpoons to tether itself to the surface, and why their failure meant that the lander bounced so far away from its landing site.
Given that Cruithne isn't much more to us at this point than a few blurry pixels on an image, it's safe to say that it sits firmly in the middling size range for non-planetary bodies in the solar system, and any human or machine explorers would face similar challenges as Rosetta and Philae did on 67P.
If Cruithne struck the Earth, though, that would be an extinction-level event, similar to what is believed to have occurred at the end of the Cretaceous period. Luckily it's not going to hit us anytime soon – its orbit is tilted out of the plane of the solar system, and astrophysicists have shown using simulations that while it can come quite close, it is extremely unlikely to hit us. The point where it is predicted to get closest is about 2,750 years away.
Cruithne is expected to undergo a rather close encounter with Venus in about 8,000 years, however. There's a good chance that that will put paid to our erstwhile spare moon, flinging it out of harm's way, and out of the Terran family.
It's Not Just Cruithne
The story doesn't end there. Like a good foster home, the Earth plays host to many wayward lumps of rock looking for a gravitational well to hang around near. Astronomers have actuallydetected several other quasi-orbital satellites that belong to the Earth, all here for a little while before caroming on to pastures new.
So what can we learn about the solar system from Cruithne? Quite a lot. Like the many other asteroids and comets, it contains forensic evidence about how the planets were assembled. Its kooky orbit is an ideal testing ground for our understanding of how the solar system evolves under gravity.
As I said before, it wasn't until the end of the 20th century that we even realized that bodies would enter such weird horseshoe orbits and stay there for such a long time. The fact they do shows us that such interactions will have occurred while the solar system was forming. Because we think terrestrial planets grow via collisions of bodies of Cruithne-size and above, this is a big new variable.
One day, Cruithne could be a practice site for landing humans on asteroids, and perhaps even mining them for the rare-earth metals our new technologies desperately crave. Most importantly of all, Cruithne teaches us that the solar system isn't eternal – and by extension, neither are we.
This article originally appeared at The Conversation and is republished here under a creative commons license. | <urn:uuid:8b194611-91cb-4aa6-8d7e-d405d2aadaa7> | 3.65625 | 1,123 | Nonfiction Writing | Science & Tech. | 56.547413 | 95,549,130 |
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Solar Eclipse 2017: Make the drive, MTSU professor says—it's worth it
Remember! Do not look directly at the sun. These tricks can help you enjoy the eclipse safely. CT Kruger/Now Media Group
Location has never been more important.
On Monday afternoon, a difference of a few miles will mean fully experiencing a once-in-a-lifetime event or pretty much missing it.
“You will want to be where you can experience the total eclipse of the sun,” Middle Tennessee State University spokesperson Randy Weiler said. “Total as in 100 percent. Darkness. And if weather permits — a clear sky or as few clouds as possible at 1:29 p.m. Aug. 21 in Murfreesboro — you’ll be able to see stars you normally do not see this time of year and planets.”
MTSU will be holding an observation party on their Murfreesboro campus Monday, and faculty and staff have been leading local conversations about the eclipse for months.
It will be worth it to make whatever drive necessary to see the event, according to MTSU of Physics and Astronomy professor John Wallin.
What, where to watch
A total solar eclipse occurs when the moon casts a shadow on Earth, blocking the sun’s light in some areas, Weiler explained. Observers within the path of totality (total eclipse) will be able to view the sun’s corona. Observers outside the path will view only a partial eclipse.
“Just 1 percent difference is not the same,” said Wallin. “It’ll get darkish, but it’s not nearly the same as a total eclipse. The difference (here) is just a few miles.”
It’s been more than 500 years since the last total eclipse threw Rutherford County, and much of the rest of the country, in total darkness in the middle of the day. It’s likely to be more than five centuries before it happens again, Wallin said.
The total solar eclipse will be on Monday August 21, and it could cost employers millions in lost productivity. Time
The coast-to-coast, Oregon to South Carolina eclipse is the buzz of the nation and astronomy world; Wallin himself is over the moon about it.
As a high school student in Hibbing, Minn., Wallin and his astronomy club drove more than 325 miles one way to Winnipeg, Manitoba, Canada, to view a total eclipse. The way he tells it, the temperature was 15 degrees below zero before the sun went dark, when the mercury plummeted further.
In Middle Tennessee, viewers must be east and north of I-24 to see totalith. MTSU’s Great Tennessee Eclipse official NASA viewing event, which will be in the green space along the Science Corridor of Innovation on campus, will receive about 1 minute, 5 seconds of total eclipse. Activities and food vendors will be on hand from from 11 a.m. to 1:45 p.m.
According to Wallin, even within the Murfreesboro city limits, location matters.
“Across I-24 at the AMC Murfreesboro 16 movie theater or Sam’s Club, there might be 30 seconds of total eclipse. Further west, Blackman High School may get a few seconds or no total eclipse,” Weiler said.
Wallin and colleagues say Riverdale High School and Barfield Park’s Wilderness Station will have zero total eclipse.
“This is different from any eclipse you’ve ever seen,” Wallin said. “A lot of people, if they don’t drive a few miles, are going to miss it.”
Rutherford County schools will be closed
Rutherford County schools will be closed Monday, while Murfreesboro City’s will remain open.
In addition to 3,000 to 4,000 combined Murfreesboro City and Rutherford County schools students originally expected at MTSU, nearly 140 University of Alabama-Huntsville students in three buses, students from a Florence, Alabama, high school and another school group in Tennessee plan to attend the MTSU event, Weiler said.
Luckily, Rutherford County residents can stay fairly local to see totality, Wallin said.
Good viewing spots across Rutherford County and Middle Tennessee
Woodbury, La Vergne, Smyrna, Lascassas, Milton, McMinnville, Brentwood, Lebanon, Watertown and other towns east and north of I-24.
Residents of other parts of Middle Tennessee should plan ahead, though. Wallin’s poor viewing spots: Rockvale, Eagleville, Christiana, Shelbyville, Lynchburg, Tullahoma, Manchester, Franklin, Spring Hill, Columbia and other communities south and west of I-24. | <urn:uuid:bbb5bcd5-f36c-40b8-8f45-babbc04314ad> | 2.5625 | 1,040 | News Article | Science & Tech. | 55.148901 | 95,549,135 |
A persistent school of thought in recent years has held that so-called "chevrons," large U- or V-shaped formations found in some of the world's coastal areas, are evidence of megatsunamis caused by asteroids or comets slamming into the ocean.
University of Washington geologist and tsunami expert Jody Bourgeois has a simple response: Nonsense.
The term "chevron" was introduced to describe large dunes shaped something like the stripes you might see on a soldier's uniform that are hundreds of meters to a kilometer in size and were originally found in Egypt and the Bahamas.
But the discovery of similar forms in Australia and Madagascar led some scientists to theorize that they were, in fact, deposits left by huge tsunami waves, perhaps 10 times larger than the devastating Indian Ocean tsunami of December 2005.
Such huge waves, they suggest, would result from the giant splash of an asteroid or comet hitting the ocean. They also suggest one such impact occurred 4,800 to 5,000 years ago, and that chevrons in Australia and Madagascar point to its location in the Indian Ocean.
But Bourgeois said the theory just doesn't hold water.
For example, she said, there are numerous chevrons on Madagascar, but many are parallel to the coastline. Models created by Bourgeois' colleague Robert Weiss show that if they were created by tsunamis they should point in the direction the waves were travelling, mostly perpendicular to the shore.
"And if it really was from an impact, you should find evidence on the coast of Africa too, since it is so near," said Bourgeois, a UW professor of Earth and space sciences who has studied earthquakes and tsunamis in various parts of the world.
In a paper in the May issue of Geology, Bourgeois and Weiss, an assistant professor of geology at Texas A&M University, conclude that "the extraordinary claim of 'chevron' genesis by megatsunamis cannot withstand simple but rigorous testing."
The scientists used an online program called Google Earth, made up of satellite images of the Earth's surface, to get close-up looks at chevrons in different locations. Chevrons often are found in coastal areas, but they also are common in semiarid areas inland.
"There are the same forms in the Palouse in eastern Washington state, and those are clearly not from a tsunami," Bourgeois said.
For the research, Weiss created a computer model that generated actual conditions that would occur during a tsunami. The scientists then used the model to examine what would happen if an asteroid or comet hit in the area theorized by the megatsunami proponents. The model showed the wave approach would be at a 90-degree orientation to the chevron deposits. But if the megatsunami interpretation is correct, the chevrons should be parallel to wave approach.
"That's just not the case here. The model shows such a tsunami could not have created these chevrons, unless you have some unimaginable process at work," Bourgeois said.
Asteroids and comets bombarded Earth in the distant past, at times with devastating consequences, such as the impact 65 million years ago that is believed to have sent dinosaurs to their extinction. There have been large impacts since but probably nothing comparable.
Proponents of the megatsunami theory have suggested that the dunes could not have been created by other forces, but Bourgeois believes their interpretation is faulty.
"They claim these are not consistent with the patterns of prevailing winds, but in fact they are consistent with the wind. They are not consistent with what a tsunami would do," she said.
The discovery of marine fossils in some chevron formations seems to support the idea that a wave created the deposit, but Bourgeois discounts that evidence also.
"Marine fossils can get into non-marine deposits. It's not uncommon. You only have to change sea level a little bit or have them wash up on a beach in a storm," she said. "And some marine organisms can be carried by the wind. I am convinced these are largely wind-blown deposits."
She noted that similar deposits have been seen on the Kamchatka Peninsula on Russia's east coast, where she has conducted research for more than a decade.
"Those are made of volcanic ash, and they are not near the coast at all, yet they look very similar to these coastal chevrons," Bourgeois said.
For more information, contact Bourgeois at (206) 685-2443 or email@example.com. | <urn:uuid:e13fc7b4-f77e-4f11-a6e1-483d87682778> | 3.921875 | 944 | Knowledge Article | Science & Tech. | 43.54681 | 95,549,136 |
The programming language Java was developed by Sun Microsystems in the year 1995. Earlier, it was only used to design and program small computing devices but later adopted as one of the platform independent programming language. The most important feature of Java is its byte code that can be interpreted on any platform including windows, Linux etc. One can also download it freely from the official website of Sun.
As we have mentioned above that java-programming language was only developed for the small devices but now it can be found in a variety of devices like cell phones, e-commerce application, PCs and almost all network or computing devices.
Java is available in different form:
JSP? Like PHP and ASP, Java Server Pages based on a code with normal HTML tags, which helps in creating dynamic web pages.
Java Applets? This is another type of Java program that used within a web page to add many new features to a web browser. These are small program used in the programming of instant messaging, chat service, solving some complex calculation and for many other purposes.
J2EE? The software Java 2 Enterprise Edition are used by various companies to transfer data based on XML structured documents between one another.
JavaBeans? This is something like Visual Basic and a reusable software component that can be easily assemble to create some new and advanced application.
As far as syntax is concerned, Java is similar as the C programming language but a distinct style of coding. It follows all the general programming features like loops, data types, conditions, curly braces, semi-colon etc. Its a fully featured Object Oriented Programming (OOP) language as it supports all OOP features including classes, modules, inheritance, Polymorphism etc.
Mobile Java - Besides the above technology, Java is also used for various entertainment devices especially mobile phone. Mobile Information Devices Profile (MIDP) uses Java run time environment in cell phones, mobile tracking systems and other traditional PDA devices. Java technology enabled application is key to the games and services available in the mobile world. This also plays an important role in the field of telemedicine such as PulseMeter. As far as mobile technology is concerned, it offers offline facility, so that users can get service even if they face loss of connection. Today, all leading mobile service provider like Nokia, Siemens, Vodafone are using Java technology. Sun Java Wireless Toolkit offers complete support for developing different MIDP application.
Java technology is enabled with healthy content ecosystem by offering a healthy development and deployment environment, protecting users and operators from down time and viruses. The increase volume of users now encouraging manufactures and developers to apply Java technology in numerous other productive and functional ways including MP3 players, digital TV, video, 3D, simplifying games, etc. | <urn:uuid:e60cd1e9-96a0-4f56-9e60-ba2a4ff5552d> | 3.171875 | 569 | Knowledge Article | Software Dev. | 24.808654 | 95,549,145 |
The first decade of the 21st century has been the warmest “by far” since instrumental records began, says the UK Met Office and the World Meteorological Organisation. Moreover, they say 2009 will almost certainly be the fifth warmest in the 160-year record. And now, El Niño conditions add to the warmth. Moreover, NASA says a new global temperature record will be set in the next year or two. The WMO and the UK weather office were giving this information to the Copenhagen conference on Tuesday. The WMO uses three temperature sets - from the UK Met Office and the University of East Anglia's Climatic Research Unit (CRU), and from the US National Oceanic and Atmospheric Administration and NASA. The scientists said the controversy around the hacked emails was a no-starter as all the data sets showed the same results. For much more on this, read the BBC
Katy Perry is the only artist to rival Michael Jackson's five billboard #one singles off one album. | <urn:uuid:5b7d86de-a02f-46d8-bcd4-24ca149e3e3e> | 2.796875 | 202 | Truncated | Science & Tech. | 48.361845 | 95,549,154 |
By: Tariq Malik
Published: 05/08/2012 05:59 PM EDT on SPACE.com
Light from an alien "super-Earth" twice the size of our own Earth has been detected by a NASA space telescope for the first time in what astronomers are calling a historic achievement.
NASA's infrared Spitzer Space Telescope spotted light from the alien planet 55 Cancri e, which orbits a star 41 light-years from Earth. A year on the extrasolar planet lasts just 18 hours.
The planet 55 Cancri e was first discovered in 2004 and is not a habitable world. Instead, it is known as a super-Earth because of its size: The world is about twice the width of Earth and is super-dense, with about eight times the mass of Earth.
This plot of data from NASA's Spitzer Space Telescope reveals the light from a "super-Earth" called 55 Cancri e.
But until now, scientists have never managed to detect the infrared light from the super-Earth world.
"Spitzer has amazed us yet again," said Spitzer program scientist Bill Danch of NASA headquarters in Washington in a statement today (May 8). "The spacecraft is pioneering the study of atmospheres of distant planets and paving the way for NASA's upcoming James Webb Space Telescope to apply a similar technique on potentially habitable planets."
Spitzer first detected infrared light from an alien planet in 2005. But that world was "hot Jupiter," a gas giant planet much larger than 55 Cancri e that orbited extremely close to its parent star. While other telescopes have performed similar feats since then, Spitzer's view of the 55 Cancri e is the first time the light from a rocky super-Earth type planet has been seen, researchers said.
Since the discovery of 55 Cancri e, astronomers have pinned down increasingly strange features about the planet. The researchers already knew it was part of an alien solar system containing five exoplanets centered on the star 55 Cancri in the constellation Cancer (The Crab). [Gallery: The Oozing Planet 55 Cancri e]
But 55 Cancri e stood out because it is ultra-dense and orbits extremely close to its parent star; about 26 times closer than the distance between Mercury and our own sun.
The new Spitzer observations revealed that the star-facing side of 55 Cancri e is extremely hot, with temperatures reaching up to 3,140 degrees Fahrenheit (1,726 degrees Celsius). The planet is likely a dark world that lacks the substantial atmosphere needed to warm its nighttime side, researchers said.
And to top it all off, the planet is oozing.
Past observations of the planet by the Spitzer Space Telescope have suggested that one-fifth of 55 Cancri e is made up of lighter elements, including water. But the extreme temperatures and pressures on 55 Cancri e would create what scientists call a "supercritical fluid" state.
Supercritical fluids can be imagined as a gas in a liquid state, which can occur under extreme pressures and temperatures. On Earth, water can become a supercritical fluid inside some steam engines.
The previous studies of 55 Cancri e were performed by analyzing how the light from its parent star changed as the planet passed in front of it, a technique known as the "transit method." In the new study, astronomers used the Spitzer Space Telescope to determine the infrared light from 55 Cancri e itself.
Spitzer's new look at 55 Cancri e is consistent with supercritical-fluid waterworld theory. The planet is likely a rocky world covered with water in a supercritical fluid state and topped off with a steam blanket, researchers said.
"It could be very similar to Neptune, if you pulled Neptune in toward our sun and watched its atmosphere boil away," said the study's principal investigator Michaël Gillon of Université de Liège in Belgium. The lead author is Brice-Olivier Demory of the Massachusetts Institute of Technology in Cambridge.
The research is detailed in the Astrophysical Journal.
NASA's $770 million Spitzer Space Telescope launched in 2003 and is currently in an extended mission to study the universe in infrared light. During that extended mission, telescope engineers modified several settings on the observatory to optimize its alien planet vision, NASA officials said.
The space agency's next major infrared space observatory, the James Webb Space Telescope slated to launch in 2018, could potentially reveal even more details about 55 Cancri e and other similar super-Earth planets.
"When we conceived of Spitzer more than 40 years ago, exoplanets hadn't even been discovered," said Michael Werner, Spitzer project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Because Spitzer was built very well, it's been able to adapt to this new field and make historic advances such as this."
This story was corrected to reflect that one year on the planet 55 Cancri e lasts just 18 hours, not one day.
BEFORE YOU GO
GALLERY: OTHER EXOPLANETS | <urn:uuid:3b142cf3-3fce-4a23-83d3-9e44819de941> | 3.453125 | 1,053 | Truncated | Science & Tech. | 44.29135 | 95,549,155 |
The Flamsteed Designation for stars was developed by astronomer John Flamsteed for his early-1700s Astronomical Catalog Catalogus Britannicus, which covered stars visible from England. It groups stars by constellation indicating its individual stars by a Latin form of the constellation (optionally abbreviated) with a preceding number. Examples: 51 Pegasi, 61 Cygni.
Some stars are still sometimes referred to by this designation, and Extra Solar Planets associated with them are often indicated by using the designation with a subsequent letter, starting with "b" for the first planet discovered. e.g., 55 Cancri e orbiting the star 55 Cancri in the constellation Cancer. | <urn:uuid:7ff09e53-bf94-4f94-a2f0-e7b3f68fbebc> | 3.53125 | 140 | Knowledge Article | Science & Tech. | 32.797941 | 95,549,159 |
ALL >> Environment >> View Article
Can Solar Power Beat Nuclear Energy Costs?
Total Articles: 33
With the Indian Government setting an ambitious goal of tripling nuclear power over the next decade, the country is well poised to double its nuclear power generation capacity to more than 10,000 mega watts (MW) over the next five years.
According to a recent analysis by indiaspend.org, a data-driven non-profit, domestic nuclear power generation has doubled in the last five years and is likely to repeat this performance over the coming five years given the new capacity addition under construction.
With more fuel available, capacity utilisation of nuclear power plants has improved from 50% in 2008-09 to more than 80% now.
The ongoing surge in nuclear power is a direct payoff of the India-US Civil Nuclear Agreement, which has already delivered clear, tangible gains for India, and will continue to do so in the coming years.
Compared to power plants using fossil fuels, such as coal or gas, nuclear power has high initial costs with the cost of the imported fuel needed to power these reactors pegged at approx INR 330 crore per annum.
However, fuel costs are a relatively small expense in the course of a nuclear plant’s lifecycle, compared to the significantly lower lifetime costs for nuclear power vis-a-vis conventional sources like coal or gas. The Nuclear Power Corporation in India (NPCIL) supplies electricity at a lower cost per unit than any other public or private energy utility in the country today.
Nuclear power plants currently account for an estimated 3.5% of India’s power generation capacity with its share in India’s future electricity generation likely to less than 10%, even if the existing installed nuclear generation capacity levels are tripled.
However, along with other sources of energy such as hydropower and solar power generation, it will play a role in reducing India’s reliance on fossil fuels like coal for generating electricity.
On the solar energy front, the government has set itself an ambitious target of increasing its solar power generation capacity five-fold to 100 GW by 2020.
Already the prices of solar photovoltaic panels in India has declined by a whopping 80% (from their 2008 levels) even as the efficiency of solar modules has pegged a annual hike in the region of approx 4.5%.
Driven by the growing demand, declining costs and capacity additions by solar IPPs in India, the cost of solar power is expected to equal those of conventional energy tariffs or go even lower to touch an per unit average price in the range of INR 4.00-4.50 over the next two years.
Already there has been a significant reduction in solar power tariffs over the last couple of years with the feed-in-tariffs (FITs), largely due to supportive trends like the improved absorption of fixed costs, declining costs of solar components and lower return expectations fuelled by market maturity, by solar IPPs in India.
Welspun Renewables is guided by its vision to power a Green India and is working towards becoming a fully-integrated power company by setting up renewable energy based power plants.
India is well-placed to achieve its target of 100GW of solar energy by 2022 if it strengthens its transmission grid, lowers financing costs and follows a consistent policy with regard to
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Author: Arun Mohan | <urn:uuid:45fd7d15-e30d-49ca-b51d-0a28b48756a8> | 3.125 | 958 | Truncated | Science & Tech. | 37.611578 | 95,549,164 |
EPFL scientists have developed a new method that turns cells into stem cells by "squeezing" them. The method paves the way for large-scale production of stem cells for medical purposes.
Stem cells are now at the cutting edge of modern medicine. They can transform into a cells of different organs, offering new ways to treat a range of injuries and diseases from Parkinson's to diabetes. But producing the right type of stem cells in a standardized manner is still a serious challenge. EPFL scientists have now developed a gel that boosts the ability of normal cells to revert into stem cells by simply "squeezing" them into shape. Published in Nature Materials, the new technique can also be easily scaled up to produce stem cells for various applications on an industrial scale.
There are different types of stem cells, but the ones that are of particular medical interest are the so-called "induced pluripotent stem cells" or iPSCs. These are derived from mature, adult cells that have been genetically reprogrammed to behave like stem cells (which is why they are "induced"). iPSCs can then be regrown into a whole range of different cells types, e.g. liver, pancreatic, lung, skin etc.
There have been many attempts to design a standardized method for generating such stem cells. But even the most successful methods turn out to not be very effective, especially for use on a large scale. A major issue is that existing techniques use the two-dimensional environment of a petri dish or cell culture flask, whereas cells in the body exist in a three-dimensional world.
The lab of Matthias Lutolf at EPFL has now developed a new method that may help to overcome these challenges. The approach uses a three-dimensional cell culture system. Normal cells are placed inside a gel that contains normal growth nutrients. "We try to simulate the three-dimensional environment of a living tissue and see how it would influence stem cell behavior," explains Lutolf. "But soon we were surprised to see that cell reprogramming is also influenced by the surrounding microenvironment." The microenvironment in this case, is the gel.
The researchers discovered that they could reprogram the cells faster and more efficiently than current methods by simply adjusting the composition - and hence the stiffness and density - of the surrounding gel. As a result, the gel exerts different forces on the cells, essentially "squeezing" them.
As a new phenomenon, this is not entirely understood. However, the scientists propose that the three-dimensional environment is key to this process, generating mechanical signals that work together with genetic factors to make the cell easier to transform into a stem cell.
"Each cell type may have a 'sweet spot' of physical and chemical factors that offer the most efficient transformation," says Lutolf. "Once you find it, it is a matter of resources and time to create stem cells on a larger scale."
The greater impact of this discovery is possibly quantity. The technique can be applied to a large number of cells to produce stem cells on an industrial scale. Lutolf's lab is looking into this, but their main focus is to better understand the phenomenon, and to find the 'sweet spots' for other cell types.
This work included a collaboration between EPFL's Institute of Bioengineering, Core Facility PTECH, and Institute of Chemical Sciences and Engineering. It was funded by the EU (Framework 7; PluriMes), SystemsX.ch (StoNets), the European Research Council, and the Swiss National Science Foundation (Singergia).
Caiazzo M, Okawa Y, Ranga A, Piersigilli A, Tabata Y, Lutolf MP. Defined three-dimensional microenvironments boost the induction of stem cell pluripotency. Nature Materials 11 January 2016. DOI: 10.1038/nmat4536
Nik Papageorgiou | EurekAlert!
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
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A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
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17.07.2018 | Power and Electrical Engineering | <urn:uuid:1933d3f0-27e0-4bcf-a77c-36e3dbe1d5e8> | 4.03125 | 1,475 | Content Listing | Science & Tech. | 43.717481 | 95,549,170 |
Accessible Web Content Structure
Creating the accessible web is a lot like building a house. Once you've got the foundation in place (understanding the “who” and “why” of web accessibility), it's time to erect the frame for the information you want to provide. By using structured HTML to create your content, you provide the semantic meaning it needs to be able to reach anyone who encounters it, whether on a laptop, via braille display, or in ways, we haven’t dreamed of yet. As a bonus, it’s also great for SEO as search engines can make better sense of it.
- Structure the page with headers, start with having the same words for the page title and the H1 and make it meaningful.
- For each of the main sections of the page, label them as H2's and subsections as H3's and each subsection under that H4 and lower as needed.
People who use assistive technologies such as screen readers are able to browse through the "sections" of a website only through the use of headings and sub-headings (h1-h6) that give a semantic structure to the page. Search engines also use the heading structure to rank content. Content well structured with headings rank higher and this improves your SEO.
How Do You Make an Accessible Content Structure?
More on content structure:
- Using headings correctly
- Using lists correctly
- Tables can be useful, but they are often abused. Learn how to be a table master
Categories of ARIA Roles
Landmark Roles - Identify content areas of a page. Help assistive devices navigate pages.
Widget Roles - Act as standalone user interface widgets or as part of larger, composite widgets.
Document Structure Roles - Describe structures that organize content in a page. Document structures are not usually interactive.
Example of Landmarks Roles
In order for some assistive technology to properly interpret your website’s menus for navigating (instead of simply interpreting them as lists of links), you need to ensure they have been coded with the appropriate HTML5 and ARIA landmark role attributes.
Below is an example of an HTML5 menu using the
<nav> <ul> <li>About us</li> <li>Services</li> <li>Contact</li> <li>Location</li> <li>Why Groovy?</li> </ul> </nav>
In order to make the structure more accessible to user agents that support ARIA as well as ensuring that user agents that don't support HTML5 can also understand the structure, adding the ARIA role="navigation" is recommended.
<nav role="navigation"> <ul role=”menu”> <li>About us</li> <li>Services</li> <li>Contact</li> <li>Location</li> <li>Why Groovy?</li> </ul> </nav>
The ARIA States and Properties
States and Properties announce the state of an element to the accessibility API. Often times, but not always, states are activated by user interaction.
For example, you can let a user know that a form input field is required by using aria-required="true". | <urn:uuid:e933b8d0-64ee-4b3b-ac44-a627caef539f> | 3 | 683 | Tutorial | Software Dev. | 43.268853 | 95,549,175 |
|Scientific Name:||Hyperoodon ampullatus (Forster, 1770)|
Hyperoodon rostratus Van Beneden & Gervais, 1880
|Taxonomic Notes:||The Northern Bottlenose Whale forms an antitropical species pair with the Southern Bottlenose Whale, Hyperoodon planifrons.|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor(s):||Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L.|
|Reviewer(s):||Hammond, P.S. & Perrin, W.F. (Cetacean Red List Authority)|
As with similar species, threats that could cause widespread declines include high levels of anthropogenic sound, especially military sonar and seismic surveys. The population remains depleted from whaling. However, the decline took place more than three generations ago; the combination of possible declines driven by vulnerability to high-level anthropogenic sound sources is believed sufficient that a 30% global reduction over three generations (53 years; Taylor et al. 2007) cannot be ruled out (criterion A).
|Previously published Red List assessments:|
|Range Description:||Northern bottlenose whales are found only in the North Atlantic, from New England, USA to Baffin Island and southern Greenland in the west and from the Strait of Gibraltar to Svalbard in the east (c. 38ºN to 72ºN; Mead 1989; Gowans 2002). There are reports from the Mediterranean Sea (Cañadas and Sagarminaga 2000), and some extra-limital records from the Baltic Sea. The best-known subpopulation of the northern bottlenose whale, the best known of all beaked whales, occurs in the waters over “The Gully,” a large submarine canyon off Nova Scotia, Canada (44ºN, 59ºW; Reeves et al. 1993). However, there have been strandings and at least one sighting as far south as North Carolina in the western Atlantic (Mead 1989). The Gully is the southernmost area of consistent northern bottlenose whale presence in the western Atlantic (Wimmer and Whitehead 2004). In the eastern Atlantic, bottlenose whales are occasionally observed off the Azores (Steiner et al. 1998), and have been seen as far south as the Cape Verde Islands (15ºN; Ruud 1937). The pelagic distribution extends from the ice edges south to approximately 30°N.|
Native:Canada; Cape Verde; Faroe Islands; France; Germany; Greenland; Iceland; Ireland; Netherlands; Norway; Portugal; Spain; Svalbard and Jan Mayen; Sweden; United Kingdom; United States
|FAO Marine Fishing Areas:|
Atlantic – northeast; Atlantic – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Global abundance has not been estimated. A rough estimate open to questions is that about 40,000 occur in the eastern North Atlantic (NAMMCO Annual Report 1995), including an estimated 5,827 (CV=16%) in the high latitudes of the eastern North Atlantic (Gunnlaugsson and Sigurjónsson 1990). Estimates for Icelandic and Faroese waters were 3,142 and 287 whales respectively, although allowance was not made in the surveys for animals not observed because of their long dives. A subpopulation of c. 163 individuals (95% CI 119-214) occurs in the Gully (Scotian Shelf). About 57% of this subpopulation is found in a 20 x 8 km core area at the entrance of the canyon at any time. Mark-recapture analysis of fifteen years of data suggest that this population is stable (Whitehead and Wimmer 2005). Most subpopulations of the species are probably still depleted, due to large kills in the past; over 65,000 animals were killed in a multinational hunt that operated in the North Atlantic from c. 1850 to the early 1970’s (Mitchell 1977; Reeves et al. 1993).|
A study by Christensen and Ugland (1983) resulted in an estimated initial (pre-whaling) population size of about 90,000 whales, reduced to some 30,000 by 1914. The population size by the mid-1980s was said to be about 54,000, roughly 60% of the initial stock size.
Historic catch distributions indicated the existence of at least six centers of abundance, each potentially representing a separate stock (Benjaminsen 1972): i) the Gully; ii) northern Labrador-Davis Strait; iii) northern Iceland; iv) and v), off Andenes and Møre, Norway, and vi) around Svalbard, Spitzbergen. Anecdotal reports from whalers suggest a north/south seasonal migration could occur in some regions but there is little strong evidence for this and whales are reported in the Gully year round. They inhabit the most northerly waters of the Barents and Greenland seas in summer (May to August).
The small resident population in the Gully is largely isolated from populations to the north (Labrador) and northwest (northern Iceland); the whales there are smaller and appear to breed at a different time of year (Whitehead et al. 1997b and are genetically distinct at both mitochondrial and nuclear markers, refuting the hypothesis of seasonal migrations between these regions (Dalebout et al. 2006). Little is known about populations in central and western North Atlantic (Reyes et al. 1993). For statistical consideration, Christensen (1975) assumed that all the bottlenose whales caught east of Greenland belonged to a single subpopulation, while Mitchell (1977) defined Cape Farewell (Greenland) to divide west and east North Atlantic catches (Culik 2004).
|Current Population Trend:||Unknown|
|Habitat and Ecology:||These cold temperate to subarctic whales are found in deep waters, mostly seaward of the continental shelf (and generally over 500-1,500 m deep) and near submarine canyons. They sometimes travel several kilometers into broken ice fields, but are more common in open water. Few whales were caught in shallow waters over the continental shelf off Labrador and in waters less than 1000 m deep off the west coast of Norway.|
The species occupies a very narrow niche; the primary food source is squid of the genus Gonatus (Hooker et al. 2001; Whitehead et al. 2003). The whales may also occasionally eat fish (such as herring and redfish), sea cucumbers, starfish, and prawns. They do much of their feeding on or near the bottom in very deep water (> 800 m, and as deep as 1,400 m; Hooker and Baird 1999).
|Use and Trade:||This species was heavily exploited in the past for multiple purposes, but there is now only a very small-scale fishery in the Faroes.|
This is one of only a few species of beaked whales to be hunted commercially on a large scale. Hunts occurred from the 1850s to the 1970s, and over 65,000 whales were killed (with many more struck but lost; Reeves et al. 1993). They have also been hunted in a drive fishery in the Faroe Islands, with over 800 taken there (Bloch et al. 1996).
By far the major bottlenose whaling nation has been Norway, though some hunting was also done by the UK, Canada and Denmark (Faroes). The northern bottlenose was sought after for its oil (including a form of spermaceti oil in the head) and later for pet food. No hunting of this species has been conducted by Norway since 1973 (Jefferson et al. 1993, Reyes, 1991. The species has been essentially unexploited for almost 30 years, with only a few animals taken in some years in the Faroe Islands (on average 2.2 whales per year in the period 1709-2002). The aggregate population was certainly reduced by whaling, and the extent of recovery is uncertain (Reeves et al. 2003). Mitchell (1977) considered that the population was severely depleted in both the early and modern whaling periods. Few incidental catches have been reported (Reyes 1991).
There are no major fisheries for squid in the Northeast Atlantic, but future developments could represent some threat. This species, like other beaked whales, is likely to be vulnerable to loud anthropogenic sounds, such as those generated by navy sonar and seismic exploration (Cox et al. 2006).
Predicted impacts of global climate change on the marine environment may affect this species of whale, although the nature of impacts is unclear (Learmonth et al. 2006).
The species is included in Appendix I of CITES.
The species was included in the International Whaling Commission schedule in 1977, with recommendations that northern bottlenose whales be granted Protected Stock status with zero catch limit (Klinowska 1991). Populations or stocks are not defined; this, together with estimates of present abundance), should be the focus of future studies (Culik 2004; Dalebout et al. 2006).
|Citation:||Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L. 2008. Hyperoodon ampullatus. The IUCN Red List of Threatened Species 2008: e.T10707A3208523.Downloaded on 18 July 2018.|
|Feedback:||If you see any errors or have any questions or suggestions on what is shown on this page, please provide us with feedback so that we can correct or extend the information provided| | <urn:uuid:a0e3337a-0b14-458d-8693-b7eb4be240c2> | 3.515625 | 2,088 | Knowledge Article | Science & Tech. | 53.96912 | 95,549,177 |
The new equation, developed by University of Michigan atmospheric and planetary scientist Nilton Renno, could allow scientists to more accurately calculate the maximum expected intensity of a spiraling storm based on the depth of the troposphere and the temperature and humidity of the air in the storm's path. The troposphere is the lowest layer of Earth's atmosphere.
This equation improves upon current methods, Renno says, because it takes into account the energy feeding the storm system and the full measure of friction slowing it down. Current thermodynamic models make assumptions about these variables, rather than include actual quantities.
"This model allows us to relate changes in storms' intensity to environmental conditions," Renno said. "It shows us that climate change could lead to increases in how efficient convective vortices are and how much energy they transform into wind. Fueled by warmer and moister air, there will be stronger and deeper storms in the future that reach higher into the atmosphere."
Renno and research scientist Natalia Andronova used the model to quantify how intense they expect storms to get based on current climate predictions. For every 3.6 degrees Fahrenheit that the Earth's surface temperature warms, the intensity of storms could increase by at least a few percent, the scientists say. For an intense storm, that could translate into a 10 percent increase in destructive power.
Renno's model is what scientists call a "generalization" of Daniel Bernoulli's 18th-century equation that explains how airplane flight is possible. Bernoulli's equation basically says that as wind speed increases, air pressure decreases. It leaves out variables that were considered difficult to deal with such as friction and energy sources (which, in the case of a whirling storm, is warm air and condensation of water vapor.) And in certain idealized situations, omitting that information works fine.
But by including these additional variables, Renno was able to broaden Bernoulli's equation to apply it to more general phenomena such as atmospheric vortices.
"The laws of physics are generally very simple," Renno said. "When you make assumptions, you are not representing the simple, basic law anymore. If you don't make assumptions, your equations have those simple, basic laws in them. It gets a little more complicated to get to the solution, but you don't introduce error, and you answer is more elegant, more simple."
Renno's work bolsters studies by others who say hurricanes have grown stronger over the past 50 years as sea surface temperatures have risen. This effect has not been extreme enough for humans to notice without looking, scientists say. Hurricane Katrina and Cyclone Nargis were not the most intense storm to hit land in the past half century. Other factors contributed to the devastation they caused.
This new model helps explain the formation of spiral bands and wall clouds, the first clouds that descend during a tornado. It's clear now that they are the result of a pressure drop where the airspeed has increased.
Renno says unifying convective vortices from dust devils to cyclones will help scientists better understand them.
"This is the first thermodynamic model that unifies all these vortices," he said. "When you unify them, you can see the big picture and you can really understand what makes them form and change."
A co-investigator on NASA's Mars Phoenix Lander mission, Renno has used his new model to calculate the intensity of dust storms in Mars' polar regions. He found that at the Phoenix landing site dust storms can have winds in excess of 200 mph.
Renno is an associate professor in the Department of Atmospheric, Oceanic and Space Sciences. Andronova is a research scientist in the Department of Atmospheric, Oceanic and Space Sciences.
A paper on the new model is published early online in the Swedish journal Tellus A. The paper is called "A Thermodynamically General Theory for Convective Vortices." It is available at: http://www3.interscience.wiley.com/journal/119879028/abstract
For more information:
Nilton Renno: http://www.ns.umich.edu/htdocs/public/experts/ExpDisplay.php?ExpID=1107Michigan Engineering:
Nicole Casal Moore | University of Michigan
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine | <urn:uuid:b31624ba-30e9-432e-a587-0ad1403b02ac> | 4.125 | 1,527 | Knowledge Article | Science & Tech. | 41.357096 | 95,549,182 |
By assuming that Maxwell’s displacement current is resulted from precessing spin of photon, electron can be considered to be induced from photon. In the vaccum, they can form a system consists of a electron, a positron and a photon. This system interact with neutron and form the atom structure. In this case, a electron that is inside of an atom always form a system with a photon. Loss of this system by photon sphere makes the atom change into dark matter(neutron-cluster) and emits a positron. Double helix trajectory of matter-antimatter pair from photon is related to string theory and a pair of entangled photon can be mediates gravity by being spin 2 itself.
Comments: 9 Pages.
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You are equally welcome to be positive or negative about any paper but please be polite. If you are being critical you must mention at least one specific error, otherwise your comment will be deleted as unhelpful. | <urn:uuid:6e8ed475-3f9f-4911-9efc-7118eae49565> | 2.859375 | 314 | Comment Section | Science & Tech. | 48.805533 | 95,549,201 |
Many issues occur when microbial bacteria contaminates human food or water; it can be dangerous to the public. Determining how the microbial are growing, it can help experts determine how to prevent the outbreaks. Biofilms are a tightly group of microbial cells that grow on living surfaces or surrounding themselves. Though biofilms are not necessarily uniform; when there are more than one type of microbial bacteria that are grown, Raman mapping is performed to determine the growth patterns. Depending on the type of microbial bacteria, they can grow in various patterns such as symmetrical or scattered on the surface. The biofilms need to be intact in order to preclude and potentially figuring out the relative intensity of different components in a biofilm mixture. In addition, it is important to determine whether one biofilms is a substrate for another biofilm to be detected. For example, it is possible if layer B appears above layer A, but layer A doesn’t appear above layer B. In this case, three types of biofilms that are grown includes Listeria(L), Ralstonia(R), and a mixture of the two (LR). Since microbe deposits on metal surfaces are quite suitable, biofilms were grown on stainless steel surface slides. Each slide was viewed under a Raman Microscope at 100X and using a 532nm laser to provide great results and sharp peaks. The mapping of the laser helps determine how the bacteria growth, at which intensity the bacteria appeared in order to identify specific microbes to signature markers on biofilms. | <urn:uuid:d4b66d50-78e9-4ab3-92fb-058dd82a6116> | 4 | 314 | Academic Writing | Science & Tech. | 35.791429 | 95,549,217 |
Species Detail - Dudresnaya verticillata - Species information displayed is based on all datasets.
Terrestrial Map - 10kmDistribution of the number of records recorded within each 10km grid square (ITM).
Marine Map - 50kmDistribution of the number of records recorded within each 50km grid square (WGS84).
(Withering) Le Jolis
1 January (recorded in 2000)
31 December (recorded in 1959)
National Biodiversity Data Centre, Ireland, Dudresnaya verticillata, accessed 22 July 2018, <https://maps.biodiversityireland.ie/Species/144> | <urn:uuid:96067049-d78f-4c71-a1cf-97820e55abd4> | 2.96875 | 139 | Structured Data | Science & Tech. | 32.419 | 95,549,242 |
How many right-angled triangles are there with sides that are all integers less than 100 units?
A floor is covered by a tessellation of equilateral triangles, each having three equal arcs inside it. What proportion of the area of the tessellation is shaded?
Explain how the thirteen pieces making up the regular hexagon shown in the diagram can be re-assembled to form three smaller regular hexagons congruent to each other.
Find the area of the annulus in terms of the length of the chord which is tangent to the inner circle.
Which is a better fit, a square peg in a round hole or a round peg in a square hole?
A tennis ball is served from directly above the baseline (assume the ball travels in a straight line). What is the minimum height that the ball can be hit at to ensure it lands in the service area?
Pythagoras of Samos was a Greek philosopher who lived from about 580 BC to about 500 BC. Find out about the important developments he made in mathematics, astronomy, and the theory of music.
Liethagoras, Pythagoras' cousin (!), was jealous of Pythagoras and came up with his own theorem. Read this article to find out why other mathematicians laughed at him.
This article for pupils and teachers looks at a number that even the great mathematician, Pythagoras, found terrifying.
Prove that a triangle with sides of length 5, 5 and 6 has the same area as a triangle with sides of length 5, 5 and 8. Find other pairs of non-congruent isosceles triangles which have equal areas.
A description of some experiments in which you can make discoveries about triangles.
Read all about Pythagoras' mathematical discoveries in this article written for students.
The diagram shows a very heavy kitchen cabinet. It cannot be lifted but it can be pivoted around a corner. The task is to move it, without sliding, in a series of turns about the corners so that it. . . .
ABCDEFGH is a 3 by 3 by 3 cube. Point P is 1/3 along AB (that is AP : PB = 1 : 2), point Q is 1/3 along GH and point R is 1/3 along ED. What is the area of the triangle PQR?
A rectangular field has two posts with a ring on top of each post. There are two quarrelsome goats and plenty of ropes which you can tie to their collars. How can you secure them so they can't. . . .
A half-cube is cut into two pieces by a plane through the long diagonal and at right angles to it. Can you draw a net of these pieces? Are they identical?
The first of two articles on Pythagorean Triples which asks how many right angled triangles can you find with the lengths of each side exactly a whole number measurement. Try it!
This is the second article on right-angled triangles whose edge lengths are whole numbers.
It's easy to work out the areas of most squares that we meet, but what if they were tilted? | <urn:uuid:d7243733-4eb0-47fb-b078-85a9d34ad04b> | 3.390625 | 648 | Content Listing | Science & Tech. | 70.133414 | 95,549,243 |
- University of Guelph
- NC State University
- Lucid via Discover Life
Proturans are rare, small creatures. They undergo anamorphosis, in which they add segments
posteriorly during development. No other insects undergo this type of metamorphosis. They are
found in most areas around the world, residing in damp, dark habitats and feeding on decaying
matter and other insects. Another unique feature is the telson tail, which is common in crustaceans
but absent in other insects. The telson tail is used for locomotion and for defense.
Proturans are small in size, less than two millimeters long. They have a delicate and
elongate body without pigment. the head is conically-shaped. The eyes and antennae are absent,
but there is a pseudoculus (sensory organ) found on the head. The mouthparts are entognathous
(exposed) and the mandibles and maxillae are slender. The adult abdomen has twelve segments. The
front legs serve as the antennae. The forelegs are enlarged with many sensillae. The legs are made
up of five segments. The gonopore is located between segments 11 and 12. The anus is terminal. They
lack cerci. (Gullan and Cranston, 2000).
- Suborder Eosentomoidea
- Family Eosentomidae
- Genus Eosentomon- 14 Species
- Suborder Acerentomoidea
- Family Protentomidae
- Genus Hesperentomon- 5 Species
- Genus Proturentomon- 4 Species
- Genus Protentomon- 6 Species
- Family Acerentomidae
- Genus Acerentulus- 17 Species
- Genus Maderentulus- 1 Species
- Genus Gracilentulus- 2 Species
- Genus Berberentulus- 3 Species
- Genus Tuxenidia- 1 Species
- Genus Acerella- 3 Species
- Genus Acerentomon- 25 Species
- Genus Tasmanentulus- 1 Species
- Genus Yinentulus- 1 Species
- Genus Kenyentulus- 1 Species
"Protura" comes from Greek words "proto-", meaning first, and "-ura", meaning tail.
This refers to the absence of advanced structures in the tail end of the abdomen.
Synonym: Myrientomata (Gillott, 1980) Common Names: Proturans, Telson Tails (Wooten, 1984)
N.C. State University Entomology Dept.
Proturans are found all over the world, with the exception of arctic and Antarctic areas.
They probably originated in moist, warm areas and later spread throughout the world.
Evolution and distribution of Protura have been very slow processes. (Tuxen, 1985)
There are four families and approximately 500 species worldwide. In North America, there are three families and 20 species.
|Number of Families
|Number of Species
Proturans hatch as prelarva and are probably immobile. The prelarva has nine segments and
underdeveloped mouthparts. There are three stages: protonymph, deutonymph, and tritonymph. The
protonymph has nine segments and developed mouth and legs. The deutonymph has ten segments. The
tritonymph has eleven segments, lesser setae and no external genitalia. Development occurs in soil
or decaying wood. Immature Protura feed on mycorrhyza, moss and litter. (Tuxen, 1985)
The adult has 12 segments. The ideal habitat for Proturans is old leaf mold along the edge of woods.
Adults feed on decaying matter, and may be found inhabiting with the nymphs for most of the year. (Ross, 1982)
Some adults feed another insects by capturing prey with sharp claws and sucking out the insides. The telson
(tail) may be used for locomotion but also has been used for defense. Proturans have been observed to curve
the tail over the head and discharging a sticky secretion on enemies (Wooten, 1984).
Suring mating, the male deposits spermatophores. An unattended female collects the sperm. This is indirect fertilization.
(Gullan and Cranston, 2000)>
How to encounter|
Proturans can be collected by examining leaf mold and drying it. They can be preserved in 70% alcohol and mounted on slides. (Ross, 1982).
Links to other sites|
- Gillott, Cedric. Entomology. 1980: Plerum Press, New York.
- Gullan, P.J. and P.S. Cranston. The Insects: An Outline of Entomology: Second Edition.
2000: Blackwell Science Unlimited.
- Nosek, Josef. The European Protura. 1973: Museum D¹Histoire Naturelle, Geneve.
- Ross, Herbert H., Charles A. and June R.P A Textbook of Entomology: Fourth Edition.
1982: John Wiley and Sons, Inc.
- Tuxen, S.L. Fauna of New Zealand: Protura. 1985: Science Information Publishing Centre, New Zealand.
- Wooten, Anthony. Insects of the World. 1984: Blanford Press, New York.
This page written by Kari McLaughlin, Ecology major, University of Georgia, Athens.
Thanks to Sabina Gupta, Denise Lim, and Dr. John Pickering for technical and web support in developing this page.
Top | See original
Following modified from University of Guelph
Class and Order - DIPLURA & PROTURA
The Diplura and Protura are primitively wingless orders (not descended from winged ancestors). Protura, which lack antennae and cerci, are tiny and rarely noticed (so I have no photographs to include here!). Diplura can be found under rocks and logs or in the soil, and are small, eyeless insects with two antennae and two tails (cerci). The most common diplurans are elongate, white Campodeidae with long cerci. The somewhat earwig-like Japygidae have forceps-like cerci.
Top | See original
Following modified from NC State University
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Updated: 2018-07-16 16:29:08 gmt | <urn:uuid:f71b5379-b0cb-4639-9ee0-3cb75e789038> | 3.84375 | 1,461 | Knowledge Article | Science & Tech. | 45.226821 | 95,549,269 |
Jaguar electric boat breaks the world’s speed record with its electric boat. As we know Jaguar is famous for its luxury vehicle brand of Jaguar Land Rover, and not only luxury vehicles but also electric cars, and what about electric boats? It really sounds fantastic, they released not only electric boat but also electric boat brakes the speed record.
Engineers from Massachusetts Institute of Technology (MIT) found out that sandwiches from one-nuclear materials of a decanter and compounds of molybdenum can be used as the super thin solar cells. The solar cells created by scientists represent sandwiches from two different two-dimensional substances with one atom thick. In one of options is used MoS2 molybdenum sulfide with a decanter, in other – the same connection with WS2 tungsten sulfide. According to scientists, the counting on quantity of the transformed energy efficiency of new solar cells is insignificant. It makes only about one percent against 15-20 percent at existing photo cells. Nevertheless, at calculation on weight, one-nuclear sheets have no equal. They receive at least in 1000 times more energy with the same weight. Similar the super thin solar cells can be used in the space industry where low weight is especially important, and the size of the panel has no basic value. The main lack of new solar batteries is complexity of industrial production. Yet, neither single-layer compounds of vanadium, nor a decanter engineers didn’t learn to receive in rather large numbers. For a long time scientists conduct works on creation not only thin, but also flexible solar cells. So, recently South Korean engineers presented solar panels on the basis of amorphous silicon which can be pasted on any smooth surfaces like transfers. Other groups of Massachusetts Institute of Technology also reported about creation of flexible solar cells on the basis of a decanter. | <urn:uuid:b09bf41b-c91c-4f91-b806-0428502a39da> | 2.828125 | 379 | News Article | Science & Tech. | 40.209512 | 95,549,321 |
branch of science concerned with the properties, composition, and structure of substances and the changes they undergo when they combine or react under specified conditions.
Chemistry can be divided into branches according to either the substances studied or the types of study conducted. The primary division of the first type is between inorganic chemistry and organic chemistry. Divisions of the second type are physical chemistry and analytical chemistry.
The original distinction between organic and inorganic chemistry arose as chemists gradually realized that compounds of biological origin were quite different in their general properties from those of mineral origin; organic chemistry was defined as the study of substances produced by living organisms. However, when it was discovered in the 19th cent. that organic molecules can be produced artificially in the laboratory, this definition had to be abandoned. Organic chemistry is most simply defined as the study of the compounds of carbon. Inorganic chemistry is the study of chemical elements and their compounds (with the exception of carbon compounds).
Physical chemistry is concerned with the physical properties of materials, such as their electrical and magnetic behavior and their interaction with electromagnetic fields. Subcategories within physical chemistry are thermochemistry, electrochemistry, and chemical kinetics. Thermochemistry is the investigation of the changes in energy and entropy that occur during chemical reactions and phase transformations (see states of matter). Electrochemistry concerns the effects of electricity on chemical changes and interconversions of electric and chemical energy such as that in a voltaic cell. Chemical kinetics is concerned with the details of chemical reactions and of how equilibrium is reached between the products and reactants.
Analytical chemistry is a collection of techniques that allows exact laboratory determination of the composition of a given sample of material. In qualitative analysis all the atoms and molecules present are identified, with particular attention to trace elements. In quantitative analysis the exact weight of each constituent is obtained as well. Stoichiometry is the branch of chemistry concerned with the weights of the chemicals participating in chemical reactions. See also chemical analysis.
The earliest practical knowledge of chemistry was concerned with metallurgy, pottery, and dyes; these crafts were developed with considerable skill, but with no understanding of the principles involved, as early as 3500 B.C. in Egypt and Mesopotamia. The basic ideas of element and compound were first formulated by the Greek philosophers during the period from 500 to 300 B.C. Opinion varied, but it was generally believed that four elements (fire, air, water, and earth) combined to form all things. Aristotle's definition of a simple body as "one into which other bodies can be decomposed and which itself is not capable of being divided" is close to the modern definition of element.
About the beginning of the Christian era in Alexandria, the ancient Egyptian industrial arts and Greek philosophical speculations were fused into a new science. The beginnings of chemistry, or alchemy, as it was first known, are mingled with occultism and magic. Interests of the period were the transmutation of base metals into gold, the imitation of precious gems, and the search for the elixir of life, thought to grant immortality. Muslim conquests in the 7th cent. A.D. diffused the remains of Hellenistic civilization to the Arab world. The first chemical treatises to become well known in Europe were Latin translations of Arabic works, made in Spain c.A.D. 1100; hence it is often erroneously supposed that chemistry originated among the Arabs. Alchemy developed extensively during the Middle Ages, cultivated largely by itinerant scholars who wandered over Europe looking for patrons.
In the hands of the "Oxford Chemists" (Robert Boyle, Robert Hooke, and John Mayow) chemistry began to emerge as distinct from the pseudoscience of alchemy. Boyle (1627–91) is often called the founder of modern chemistry (an honor sometimes also given Antoine Lavoisier, 1743–94). He performed experiments under reduced pressure, using an air pump, and discovered that volume and pressure are inversely related in gases (see gas laws). Hooke gave the first rational explanation of combustion—as combination with air—while Mayow studied animal respiration. Even as the English chemists were moving toward the correct theory of combustion, two Germans, J. J. Becher and G. E. Stahl, introduced the false phlogiston theory of combustion, which held that the substance phlogiston is contained in all combustible bodies and escapes when the bodies burn.
The discovery of various gases and the analysis of air as a mixture of gases occurred during the phlogiston period. Carbon dioxide, first described by J. B. van Helmont and rediscovered by Joseph Black in 1754, was originally called fixed air. Hydrogen, discovered by Boyle and carefully studied by Henry Cavendish, was called inflammable air and was sometimes identified with phlogiston itself. Cavendish also showed that the explosion of hydrogen and oxygen produces water. C. W. Scheele found that air is composed of two fluids, only one of which supports combustion. He was the first to obtain pure oxygen (1771–73), although he did not recognize it as an element. Joseph Priestley independently discovered oxygen by heating the red oxide of mercury with a burning glass; he was the last great defender of the phlogiston theory.
The work of Priestley, Black, and Cavendish was radically reinterpreted by Lavoisier, who did for chemistry what Newton had done for physics a century before. He made no important new discoveries of his own; rather, he was a theoretician. He recognized the true nature of combustion, introduced a new chemical nomenclature, and wrote the first modern chemistry textbook. He erroneously believed that all acids contain oxygen.
The assumption that compounds were of definite composition was implicit in 18th-century chemistry. J. L. Proust formally stated the law of constant proportions in 1797. C. L. Berthollet opposed this law, holding that composition depended on the method of preparation. The issue was resolved in favor of Proust by John Dalton's atomic theory (1808). The atomic theory goes back to the Greeks, but it did not prove fruitful in chemistry until Dalton ascribed relative weights to the atoms of chemical elements. Electrochemical theories of chemical combinations were developed by Humphry Davy and J. J. Berzelius. Davy discovered the alkali metals by passing an electric current through their molten oxides. Michael Faraday discovered that a definite quantity of charge must flow in order to deposit a given weight of material in solution. Amedeo Avogadro introduced the hypothesis that equal volumes of gases at the same pressure and temperature contain the same number of molecules.
William Prout suggested that as all elements seemed to have atomic weights that were multiples of the atomic weight of hydrogen, they could all be in some way different combinations of hydrogen atoms. This contributed to the concept of the periodic table of the elements, the culmination of a long effort to find regular, systematic properties among the elements. Periodic laws were put forward almost simultaneously and independently by J. L. Meyer in Germany and D. I. Mendeleev in Russia (1869). An early triumph of the new theory was the discovery of new elements that fit the empty spaces in the table. William Ramsay's discovery, in collaboration with Lord Rayleigh, of argon and other inert gases in the atmosphere extended the periodic table
Organic chemistry developed extensively in the 19th cent., prompted in part by Friedrich Wohler's synthesis of urea (1828), which disproved the belief that only living organisms could produce organic molecules. Other important organic chemists include Justus von Liebig, C. A. Wurtz, and J. B. Dumas. In 1852 Edward Frankland introduced the idea of valency (see valence), and in 1858 F. A. Kekule showed that carbon atoms are tetravalent and are linked together in chains. Kekule's ring structure for benzene opened the way to modern theories of organic chemistry. Henri Louis Le Châtelier, J. H. van't Hoff, and Wilhelm Ostwald pioneered the application of thermodynamics to chemistry. Further contributions were the phase rule of J. W. Gibbs, the ionization equilibrium theory of S. A. Arrhenius, and the heat theorem of Walther Nernst. Ernst Fischer's work on the amino acids marks the beginning of molecular biology.
At the end of the 19th cent., the discovery of the electron by J. J. Thomson and of radioactivity by A. E. Becquerel revealed the close connection between chemistry and physics. The work of Ernest Rutherford, H. G. J. Moseley, and Niels Bohr on atomic structure (see atom) was applied to molecular structures. G. N. Lewis, Irving Langmuir, and Linus Pauling developed the electronic theory of chemical bonds, directed valency, and molecular orbitals (see molecular orbital theory). Transmutation of the elements, first achieved by Rutherford, has led to the creation of elements not found in nature; in work pioneered by Glenn Seaborg elements heavier than uranium have been produced. With the rapid development of polymer chemistry after World War II a host of new synthetic fibers and materials have been added to the market. A fuller understanding of the relation between the structure of molecules and their properties has allowed chemists to tailor predictively new materials to meet specific needs.
- See A Short History of Chemistry (1965). ,
- General Chemistry (1984). ; ,
- L. Pauling, General Chemistry (3d ed. 1991).
- R. C. Weast, ed., CRC Handbook of Chemistry and Physics (published annually).
Nouns 1 chemistry organic chemistry, inorganic chemistry, physical chemistry, chemical physics, theoretical chemistry, quantum...
Chemistry underwent the most profound changes of any science during the Enlightenment. Its vocabulary, subject matter, range of available...
Bensaude-Vincent Bernadette Isabelle Stengers , A History of Chemistry , translated from the French by Deborah van Dam ,... | <urn:uuid:2d08e8b6-0c17-4e01-8dc1-6ae4958c81f3> | 3.46875 | 2,086 | Knowledge Article | Science & Tech. | 37.354602 | 95,549,323 |
This application provides global-scale biological and ecosystem information on symbiotic zooxanthellae called Symbiodinium which are uni-cellular, photosynthetic dinoflagellates that live inside the cells of other marine organisms like anemones, jellyfish, and corals.
Symbiodinium are responsible for providing energy to their coral hosts which drives the deposition of calcium carbonate and results in the creation of coral reefs. The differential responses of corals and Symbiodinium types to environmental stressors have important implications for the resiliency of coral reef ecosystems to climate change. Dr. Tim McClanahan, Senior Conservation Zoologist for the Wildlife Conservation Society, stated that, "Given the pace of climate change and scientific developments around
Symbiodinium, GeoSymbio will catalyze the use of this knowledge towards increasing reef resilience and improved management decisions".
The genus Symbiodinium encompasses nine distinct genetic lineages or clades, with many sub-cladal types within each clade. The GeoSymbio application provides the genetic identification and taxonomic description of over 400 distinct Symbiodinium subclades in invertebrate hosts that have been sampled from a variety of marine habitats, thereby providing a wealth of information for symbiosis researchers in a single online location. By utilizing Google Apps, the team was able to develop this web-based tool to discover, explore, visualize, and share data in a rapid, cost-effective, and engaging manner.
GeoSymbio is the first comprehensive effort to collate and visualize Symbiodinium ecology, diversity, and geography in an online web application that is freely accessible and searchable by the public. To provide access to this information, GeoSymbio was designed to serve four basic functions: (1) geospatial visualization, (2) text-based queries, (3) knowledge summaries, and (4) downloadable data products for further analyses. The application structure draws information from a variety of digital sources and uses a suite of query and visualization tools, with the core of the application hosted remotely or "in the cloud" using Google Sites.
The application's development began in early 2011, when the HIMB researchers were tasked with compiling global data on coral-based Symbiodinium for analysis, as part of the "Tropical Coral Reefs of the Future" working group at the National Center for Ecological Analysis and Synthesis (NCEAS). In previous years, the team had created a database with approximately 2500 records of these Symbiodinium data from sources such as GenBank (the primary repository for Symbiodinium and all other organisms' genetic sequence information) and journal articles, however, the information was only accessible within the research group. This changed in 2011 when the research team decided to create and share a low-cost, integrative web application based on the symbiont database.
Erik Franklin, one of the lead developers of the project is excited about the product that he recently presented at the Environmental Information Management 2011 Conference. He stated that: "building the capacity to examine the diversity of Symbiodinium on coral reefs has global and societal implications for tropical nations and thus, the dissemination of this information is essential. One of the major barriers to progress was that the geographic details of the Symbiodinium records were not documented well in existing databases, and our GeoSymbio app now resolves this problem and provides open data sharing". GeoSymbio provides the first and only web-based application for data discovery, visualization, and sharing of global-scale Symbiodinium research. This tool should expedite new insights into their ecology, biogeography, and evolution in the face of a changing global climate.
Carlie Wiener | EurekAlert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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posted by Greg
A 10kg particle undergoes simple harmonic motion with an amplitude of 2.0mm, a maximum acceleration of 8.0x10^3 m/s^2, and an unknown phase constant (phi) What are:
a.) the period of the motion
b.) the maximum speed of the particle
c.) total mechanical energy of the oscillator
What is the magnitude of the force on the particle when the particle is at:
d.) its maximum displacement
e.) half its maximum displacement
I have the answers from the back of the book, but I don't know which equations to use! Any help would be very appreciated!
I am going to assume you are in calculus.
x(t)=2E-4 * sin(wt+Phi)
v(t)=w*2E-4 * cos(wt+Phi)
You know the w=2PI/period, so given max a, find w, and then period.
then max speed.
total ME? 1/2 m (maxv)^2
for the last q, remember F=ma
You know max acceleration occures when the sin term is 1, so max a= w^2*2E-4
i rekomend not pgysics as coorse ligjht | <urn:uuid:9c7a8ed6-fb2c-4e88-bb5b-1baceed35c6c> | 2.8125 | 276 | Q&A Forum | Science & Tech. | 83.960151 | 95,549,359 |
Innovative measuring chamber for X-ray study of liquid jets
Until now, the only way to study liquids by soft X-ray emission spectroscopy (XES) has been through a membrane window. Now, researchers of Helmholtz-Zentrum Berlin have carried out an XES study of a free micro-liquid jet on the synchrotron.
X-rays are the medium of choice for many scientific studies. When you shine them on a sample, they literally shed light on the material's structure, providing loads of information about it. Unfortunately, this mostly applies to solids only, since the sample has to be in a vacuum for the entire time it is being irradiated with soft X-rays. For liquids, that means you have to remove all the water. In the case of biological samples such as proteins, however, this destroys their natural environment. The solution to this problems has always been to measure liquids through membranes. These membranes keep the evacuated side separate from the non-evacuated side. The trouble is, one can never really be sure whether or not membrane effects are distorting the measurement results.
At Helmholtz-Zentrum Berlin (HZB), Emad Aziz, head of a junior research group, has shown that liquids can be investigated by X-ray emission spectroscopy without using membranes after all. At the synchrotron source BESSY II, the group has built a special setup - the LiXEdrom. It is unique in that the liquid is shot as a jet through the X-ray beam. The jet from the nozzle becomes so thin and, at 80 metres per second, so fast that the vacuum can be maintained without the need of a membrane.
"On our LiXEdrom, we create a vacuum in the liquid chamber of up to 10-6 millibar, and can now perform both absorption and emission measurements, giving us even more precise information about the structure of a material," says Emad Aziz. It also allows a clear "view" of elements that possess absorption and emission energies similar to the energies of the membrane materials, and would therefore overlap with the membrane in the spectrum when measured. This concerns above all carbon and nitrogen - precisely those elements of interest in biological samples.
In their first measurements, published in Chemical Physics (DOI: 10.1016/JChemPhys.2010.08.023) and selected for the cover, the group demonstrated they can achieve energy resolutions on their LiXEdrom comparable to those of the latest high resolution XES spectrometers. For water, they have proven that results obtained from an earlier setup were not overlapped by disturbing membrane effects. They have also studied the electronic structure of nickel ions, unhampered by a risk of deposits on a membrane wall distorting the results. For many applications such as protein studies, this is a significant step towards obtaining reliable structural information.
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- New model for bimolecular reactions in nanoreactors (08/10/2017) | <urn:uuid:158bcbca-e22d-4e90-9b79-50edfcf8f1e5> | 2.984375 | 717 | News Article | Science & Tech. | 40.428007 | 95,549,410 |
Earth is the only planet in the solar system with large quantities of surface water, and with water comes all the things that dissolve in it, including salt. In fact, salt is such an important component of seawater that evidence of it on other planets points to the past or present existence of water and possibly life. Salt isn't easy to detect, but there is evidence for it on other planets.
Terrestrial Ocean Salinity
Most of the salt in Earth's oceans is sodium chloride, which is the same salt you find on the dinner table, but there are other salts as well, including potassium chloride, sodium bromide and potassium fluoride. The salinity of the world's oceans, which averages around 35 parts per thousand, is an important regulator of metabolism, both for marine and terrestrial life. Salinity increases in a land-locked sea as the water evaporates until the sea can no longer support life, and all that's left is a whitish or grayish surface deposit. Utah's Bonneville Salt Flats is a well-known example of such a deposit.
Salt on Mars
In 2008, a team of scientists from the University of Hawaii and Arizona State University reported the discovery of deposits of chloride minerals -- which are salts -- in basins and valleys on Mars. The discovery was the result of analyzing spectral data from a multiwavelength camera aboard NASA's Mars Odyssey orbiter. The deposits occur in low-lying areas surrounded by channels and fissures consistent with the erosion caused by running water. Because the deposits are isolated from each other, scientists don't believe Mars had an ocean. It's more likely that groundwater welled up to the surface and evaporated.
Salt on Europa
Scientists have long agreed that Jupiter's moon Europa harbors a planetary ocean of liquid water beneath its thin crust. Early in 2013, astronomers Mike Brown and Kevin Hand reported evidence of an interchange between the surface crust and the subterranean ocean, and they also reported detecting the spectroscopic signature of epsomite, which on Earth is known as Epsom salts. They detected magnesium sulfate and magnesium chloride, too. The scientists surmise that the magnesium could only come from the oceans, suggesting that Europa's oceans may be as salty as those on Earth, and therefore capable of supporting life.
Salt on Enceladus
Soon after it entered orbit in around Saturn in 2004, the Cassini spacecraft detected a plume of water and ice emanating from the south pole of Enceladus, one of the Saturnian moons. Cassini passed through the plume in 2008 and found salt-rich grains of ice close to the moon's surface, suggesting the presence of a salt ocean beneath the crust. The salt-poor grains end up being ejected from the moon and forming Saturn's E-ring, but the salt-rich ones, which are heavier, fall back to the surface. Scientists believe that Enceladus has a watery layer about 80.5 kilometers (50 miles) below its surface, and they now have evidence that the water is salty. | <urn:uuid:53a2d4bc-4e38-4596-98b6-082e5cdbcb6e> | 3.9375 | 624 | Knowledge Article | Science & Tech. | 39.360294 | 95,549,436 |
Lauren Kipp, a graduate student in the MIT-WHOI Joint Program in Oceanography, spent 65 days on the U.S. Coast Guard icebreaker Healy in the summer of 2015, conducting research on chemical changes in the Arctic Ocean. (Erin Black, Woods Hole Oceanographic Institution) [ Hide caption ]
I was about fifteen minutes into my nap when I heard the announcement: “Polar bear. Port beam. One hundred yards. Huge.”
I paused to consider: Would this be worth losing some of the only precious moments of sleep I could steal before I had to return to the lab? But it didn’t take long to decide. I extracted myself from my bunk aboard the Coast Guard icebreaker Healy and—slowly, to avoid hitting my head again—I threw on as many wool layers as I could find. Was my camera in my room, or in the lab? The lab, I decided, and made my way there, begrudgingly getting in my daily arm workout as I opened and closed each of the ship’s heavy metal watertight doors in my path.
By the time I got outside, the deck was crowded with spectators, scientists and crew alike. The polar bear did not disappoint. She cautiously investigated the ship for the better part of an hour, sniffing the air and rolling around on the ice, before ambling off toward the white horizon. Now I was definitely too excited to go back to sleep.
Arctic wildlife sightings highlighted my emails home, but they weren’t the reason I had undertaken this 65-day journey on the Healy. The Arctic is a unique ocean, and it’s also uniquely susceptible to climate change. Temperatures are rising twice as fast in the Arctic as they are in the rest of the world. Sea ice is already noticeably diminishing, and that is causing far-flung environmental effects across the region.
Climate change could alter the very chemistry of the Arctic Ocean. That’s what I was aboard the Healy to study, and what I discovered was unexpected: The chemistry of Arctic waters is already rapidly changing. These chemical changes indicate that large-scale changes are occurring in how the ocean interacts with the land along the coasts. They signal changes that potentially could affect the Arctic food chain, from microbial life right up to polar bears.
On typical world maps, the Arctic Ocean stretches across the top, where it forms a thin blue border around the Northern Hemisphere. At a glance, it looks similar in size to the Atlantic and Pacific Oceans. But in fact, the Arctic is quite different from its southern siblings.
It’s a tiny ocean, with only three percent of the volume of the Pacific. It’s also surrounded by land, and that land extends far out beneath the ocean surface to form vast shallow continental shelves.
Shelves cover more than half the area of the Arctic Ocean, and that’s what makes this ocean my dream study location (well, notwithstanding the freezing temperatures and 24-hour darkness in winter). Why? Because the continents and continental shelves surrounding the Arctic Ocean have significant impacts on the ocean’s chemistry.
Rich layers of sediments accumulate atop continental shelves. The sediments are chock-full of elements and chemical compounds that are released and dissolved into overlying seawater. The process is almost similar to steeping teabags, but instead of adding flavor to the water, shelf sediments release chemicals.
In this process the coast and shelves and ocean all interact with one another in complicated ways. But things may be becoming more complicated because of climate change. Melting sea ice creates more open water near the coast for winds to create waves over shallow Arctic shelves. These more turbulent seas can intensify the erosion of coastlines. Rougher waters reach down and stir up the sediments on shelves, so that more chemicals are released and carried up and away into the ocean by currents.
To predict how these shifts will affect the chemistry of the Arctic Ocean, we need to measure these complex interactions and find ways to monitor changes. That isn’t easy to do, especially over large shelf areas. But, luckily, I had just the tool for the job.
Radium is a naturally occurring radioactive element discovered in 1898 by Marie Curie. All soil, rocks, and sediments contain radium. It also dissolves in salty water, so ocean waters pick up radium when they wash over continental shelves or brush against coastlines. That makes radium an excellent tracer to track land-based materials in the open ocean. We can track where it came from, and determine how long ago it left the shelf.
If we find high levels of radium in seawater in the open ocean, it tells us that the water touched the shelf recently. It also allows us to trace other important chemical compounds that likely were also added to the ocean from shelf sediments at the same time as the radium. These include essential nutrients that are carried up to the surface and sustain life there.
Radium was my element of choice, but many scientists were aboard the Healy to study a wide range of chemicals. The cruise was part of the international GEOTRACES program, aimed at measuring elements and chemical tracers in the world’s oceans to understand their current distributions and to provide a baseline to assess future chemical changes.
Over our two-month voyage in the summer of 2015, I collected samples along the Healy ’s path through the Bering Strait, across the Chukchi Shelf, and through the Western Arctic all the way to the North Pole (where, of course, I paused to take a picture with the iconic red and white striped pole).
To measure the radium in Arctic waters, I used a pump to pull seawater up a hose draped over the side of the Healy. I filtered the water through acrylic fibers that were coated with manganese, which makes the fibers turn black, so they look like gorilla hair. The manganese acts like a sponge. It soaks up the radium from seawater as the water passes through the fibers.
The icebreaker stopped in 69 locations along the way, and at each sampling station, I concentrated the radium from hundreds of liters of seawater onto a bundle of fiber about the size of your cell phone. The fibers were then shipped back to the lab in Woods Hole to be analyzed.
I was surprised by what I found.
Because continental shelves are the source of radium, I expected to find the highest radium levels over the Chukchi Shelf. But when I measured my samples, I realized that there was actually more radium in the central Arctic, near the North Pole.
I had expected the radium levels I observed in 2015 to be similar to those previously measured by other scientists in 2007. I was surprised to find that the amount of radium in surface waters near the North Pole had drastically increased over this time period. The levels we measured in 2015 were twice as high as those measured in 2007.
To answer the second question, I scrutinized a few maps of water circulation in the Arctic and quickly fixated on the Transpolar Drift, a strong current that carries water from the continental shelves north of Russia across the central Arctic and eventually out the Fram Strait near Greenland. I realized that the high levels of radium in the middle of the Arctic Ocean were indeed coming from a shelf—just not the one we had crossed on our way out to the central Arctic!
These Russian shelves are in a region of the Arctic experiencing some of the strongest warming. Rapidly rising air and sea temperatures are increasing the number of ice-free days over these shelves. The loss of sea ice allows for stronger wind and wave action, which could increase erosion on the coast and turbulence over the shelf—and thereby add more radium and other materials from sediments to the ocean.
The dramatic increase in radium in the central Arctic Ocean indicates that these large-scale coastal changes—less sea ice, more turbulence, and more dissolved chemicals transported from the shelves into the open ocean—are already happening.
Radium does not play a role in sustaining life in the ocean, but it comes from the same continental shelf sources as the nutrients and metals that nourish tiny marine organisms living in sunlit surface waters. Just as people require iron in hemoglobin to transport oxygen in our blood, marine organisms need small amounts of metals to keep their bodies functioning.
The increased inputs of radium to the central Arctic imply that there must also be increased inputs of other, biologically important, elements.
The tiny plants and animals living in Arctic surface waters are already trying to adjust to the loss of sea ice, which is increasing the amount of sunlight they receive. Changes in the amounts of essential nutrients coming from continental shelves would also force adjustments. Some species might flourish in waters with higher nutrient and metal concentrations, but others that are better adapted to living in nutrient-poor conditions could become scarce.
It is important to understand and monitor these shifts because changes that affect species at the bottom of the food chain eventually will have significant impacts on a wide range of Arctic organisms, from shrimp to narwhals to humans.
This ultimately is what motivated me and the other scientists onboard the Healy. The Arctic is a difficult place to do field work, but not many locations offer glimpses of the Northern Lights, polar bear sightings, and interesting chemistry! I am eager to return and learn more about this unique ecosystem. Just let me find my wool layers first.
The National Science Foundation funded this research. Kipp is also supported by a National Defense Science & Engineering Graduate Fellowship. | <urn:uuid:427933e0-8bb1-49e3-98eb-802eeff4d2bb> | 3.09375 | 1,986 | Nonfiction Writing | Science & Tech. | 46.902196 | 95,549,445 |
Ecological research has revealed a confusing interplay of a multitude of processes at different scales. It seems that ecosystems are extremely complex, difficult to understand, and different effects can hardly be differentiated. On the other hand, ecosystems and landscapes clearly exhibit structures and are far from being random ensembles of single entities.
Experts often agree that some phenomena are more typical compared to others for given systems, although often without being able to give a clear reason for that assessment. This provides some evidence that ecosystems are much more constrained than current theory and models would predict. The approach presented in this talk is based on the working hypothesis that landscapes are highly constrained systems which results in a low intrinsic dimensionality of landscape (or ecosystem) processes. That means that often only a small number of processes prevail the observed temporal or spatial patterns in landscapes, e.g., of solute concentration, groundwater heads, soil moisture, or air moisture.
This hypothesis can be tested. Furthermore, it provides a basis for very efficient ways to analyse ecosystem behaviour. Due to their ease of use, some are suggested for environmental agencies to test for unexpected behaviour and to differentiate between natural and anthropogenic effects.
Last but not least, powerful methods can be derived to test and to optimize the structure of complex ecosystem models and to deepen our knowledge of landscape processes.
|Mo. 16.07.2018 aktuell|
Ermittlung von Grundwasserverweilzeiten mittels Radon als natürlichem Tracer für ein Trinkwasserförderungsgebiet der Stadt Fürth
Absolventenfeier Geoökologie 2018/19 | <urn:uuid:c41a9581-7058-47d7-bd32-32944ee34d41> | 2.703125 | 346 | News (Org.) | Science & Tech. | 24.334464 | 95,549,481 |
What Is Regression Testing? Best Practices, Tutorials, and More
What Is Regression Testing? Best Practices, Tutorials, and More
It's a practice all developers should know about, but we could all use a little help. Read on for helpful information (and a little refresher) on regression testing.
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We talked a bit about the Software Development Life Cycle (SDLC) in a recent post, but today, we’re going to dig a little deeper into one specific and crucial element in the testing phase, particularly for Agile development: regression testing.
Definition of Regression Testing
Regression testing refers to the process of testing a changed or updated computer program to make sure the older software features – which were previously developed and tested – still perform exactly as they did before. One way to think about software regression is to think about somebody who implements a new air conditioning system in their home only to find that while their new air conditioning system works as expected, the lights no longer work.
Regression testing will often involve running existing tests against the modified code to make sure that the new code did not break anything that worked before the update. Regression testing can eliminate much of the risk associated with software updates. In addition to running existing tests, testers might tweak existing tests by introducing different secondary conditions as variables.
The Importance of Regression Testing
With the increased popularity of the Agile development methodology, regression testing has taken on added importance. Many companies today adopt an iterative, Agile approach to software development. For example, the great many software as a service (SaaS) providers will regularly update their features or add new functionality to their offerings with each software update. To ensure their core product remains unaffected by new feature additions, these companies will perform regression testing.
Regression testing is a fundamental part of the software development lifecycle. ProtoTech Solutions illustrates the concept nicely with this graph:
The Challenges of Regression Testing
While regression testing is a vital element of the QA process, there are a number of challenges it brings:
- Time Consuming: Regression testing can take a lot of time to complete. Regression testing often involves running existing tests again, so testers might not be overly enthusiastic about having to re-run tests.
- Complex: Another thing to consider here is that as products get updated, they can grow quite complex, causing the lists of tests in your regression pack to grow to a huge amount.
- Communicating Business Value: Regression testing ensures existing product features are still in working order. Communicating the value of regression testing to non-technical leaders within your business can be a difficult task. Executives want to see the product move forward, and making a considerable time investment in regression testing to ensure existing functionality is working can be a hard sell.
Regression Testing Best Practices:
As you and your team perform regression testing, there are a number of best practices to bear in mind:
- Regularly Update Your Regression Pack: A regression pack is a collection of test cases that are performed as each new software update is completed. The scripted tests included in a regression pack are created with the requirement specifications of older versions of the software in mind. Random or ad-hoc tests may also be included in the pack. It is a good idea to keep your regression pack up to date. Regression testing can be time-consuming; the last thing you need is to include tests that check whether an older feature which has been removed is still working.
- Focus on Highly-Trafficked Paths: Highly-trafficked paths are the most frequent use cases for your application. They will include the basic functionality of your application and most popular features. You should know your core group of users and the typical features and interactions they are most reliant on. Your regression pack must include tests that ensure this core functionality is working as it should.
- Re-Run Successful Test Cases: Tests that have previously identified bugs and defects are also worth including in your regression pack. Alternatively, tests that the program passes consistently are good candidates for archival.
- Automate: Automated regression testing can make the process much more efficient. Running the same tests over and over again can result in testers becoming bored and losing motivation. The quality of their work might suffer as well as motivation dips. Automated regression testing can free up your testers to work on the trickier case-specific tests. Automation software can handle the more tedious tests. Another consideration here is that testing software can be re-used, so even though there is an initial outlay, you are making efficiency gains on an ongoing basis, meaning your testing software will quickly demonstrate ROI.
The Difference Between Regression Testing and Retesting
Regression testing should not be confused with retesting. Regression testing is performed to ensure updated code has not caused any existing functionality to break. Retesting, on the other hand, refers to tests that are performed when a test case has identified some defects. Once the defects have been fixed, the tests are performed again to ensure the issues have been resolved.
Retesting is a higher priority than regression testing because issues have already been identified. Regression testing is focused on identifying potential issues.
Regression Testing Tutorials and Tips
Because regression testing can involve varying types of tests, there’s no single, clear-cut method for performing a “regression test,” per se. However, there are plenty of valuable insights and informative tutorials for incorporating regression testing practices into your overall SDLC. Check out the following tutorials and guides for more insights on selecting test cases, creating and executing a regression testing plan, best practices, and more:
- Regression Testing Fundamentals
- How to Conduct Regression Tests
- 9 Tips for Selecting Test Cases for Regression Testing
- The Challenges Posed by Regression Testing
- Importance of Regression Testing in Software Development
- Regression Testing Best Practices
- Rapid Testing For Rapid Maintenance (an older, but still valuable article)
Published at DZone with permission of Angela Stringfellow , DZone MVB. See the original article here.
Opinions expressed by DZone contributors are their own. | <urn:uuid:4e6a20b7-6352-4346-b634-823eebab4857> | 2.78125 | 1,303 | Truncated | Software Dev. | 27.451859 | 95,549,500 |
The secondary pollutants formation in the atmosphere, such as ozone (O3), comes from the reactions between volatile organic compounds (VOCs) and the photochemical oxidants in the presence of oxygen and nitrogen oxides (NOx). The understanding of VOCs reactivity emitted by light duty vehicles is very important to construct reactivity scales regarding ozone formation.In 2003, flex-fuel vehicles were released in the Brazilian market and nowadays, they represent over 50% of the total light duty vehicle fleet in the country. In 2007, new tailpipe emission limits were implemented for Non-Methane Hydrocarbons (NMHC), a group of pollutants included in VOCs. The new NMHC limit became a challenge to homologate some flex-fuel models, when fueled with ethanol. To deal with this issue, other legislation allowed the subtraction of the unburned ethanol emission from the NMHC value. In 2010, a local environmental agency published a study mentioning the need to revise this subtraction, since the unburned ethanol can also contributes to ozone formation. To better understand this issue, it was created, in 2012, a working group in Brazil, to discuss about vehicle exhaust gases reactivities to form ozone.This paper presents theoretical concepts and a calculation methodology to estimate the potential reactivity of the VOCs to form ozone. It also includes emission experimental results for different vehicles using gasoline, ethanol and Compressed Natural Gas (CNG). | <urn:uuid:32d46b10-b49d-4a37-a1db-658e12515943> | 2.96875 | 294 | Academic Writing | Science & Tech. | 19.808821 | 95,549,514 |
First 3-D Map of a Fruit Fly’s Brain Network
Mapping the 3-D network structure of a fly’s brain is a major step forward. But it took 1,700 person-hours to complete, meaning that human labor will be a significant bottleneck for future advances.
An important goal in neuroscience is to understand the structure of links between neurons that make up the brain: in other words, to build an accurate 3-D map of the brain’s neural network.
Researchers have made significant progress with various kinds of high-resolution imaging techniques. For example, attaching fluorescent molecules to neurons can show their structure, and electron microscope images of brain sections can also reveal structure at the neuronal level.
These techniques all have an important limitation. The images they produce show changes in image intensity. But these variations must then be interpreted to infer the position and shape of the actual neurons. This final step is a difficult task when the neurons and the connections between them number in the thousands and millions.
What’s needed is a better way of creating a 3-D wiring diagram of the brain—a kind of skeleton of the neural connections.
Today, that becomes possible thanks to the work of Ryuta Mizutani and pals at Tokai University in Japan. These guys have repurposed a technique for producing skeleton-like models of molecules and used it to map the neurons in a fruit fly’s brain. The result is the first 3-D model of this network of neurons.
The background to all this lies in biochemistry. Biochemists face a similar problem when they create 3-D models of complex molecules. They begin by creating a crystal of the molecule of interest. Then they zap it with x-rays and measure the diffraction pattern this forms, a technique known as x-ray crystallography.
But there is a problem. The x-rays are diffracted by the cloud of electrons that buzz around the atoms in the molecule. So the data reflects changes in electron density inside the molecule. The actual positions of the atoms have to be inferred from this data. When the structure is complex, this is not a simple task.
Chemists have a great deal of experience with this. For some years, they have used a computer modeling approach to solve the problem. It works by estimating the position of one atom in three-dimensional space, placing a node at that location in the model, and then connecting it by a virtual wire to the estimated position of the next atom, and so on. In this way, the software builds up a virtual wire model of the molecule.
Now Mizutani has repurposed this software to determine the 3-D position and shape of neurons. This is trickier because the neurons aren’t point-like objects like atoms but line-like objects that can twist and curve in complex ways.
The team gathers its data using a technique called x-ray tomography. They pickle a fly brain in a silver dye, bombard it with x-rays, and then measure the way the x-rays are scattered in various directions. This produces a 3-D image intensity map of the way silver in the neurons absorb x-rays.
The next step is the key: using the data to estimate the position and shape of the actual neurons. Mizutani and co place the data in a three-dimensional space of 840 by 1,250 by 1,200 voxels. They use the x-ray absorption intensities to estimate whether a neuron is present in particular voxel. Then they build a wire model by estimating how the neuron extends into any of the adjacent voxels.
Of course, the model has to check that the resulting network is consistent—that two adjacent neurons aren’t interpreted as a single extended neuron, for example. So the software continually checks the nature of the resulting network, looking for potential anomalies. Any anomaly that it can’t resolve is left for a human operator to fix.
This model has a resolution of around 600 nanometers and shows around 100,000 neurons, which the model resolves into about 15,000 traces. It was a significant effort for the team. “It took 1,700 person-hours to build the skeletonized model,” they say.
But the results are clearly worth it. The technique produces the first 3-D wire model of a fly brain hemisphere in which the position and shape of each neuron is mapped using 3-D Cartesian coordinates.
This model shows a wide range of known neuronal structures—the model mapped out 360 separate neuronal processes. But it also revealed a number of unknown structures that are clearly important. “These results suggest that neurons that cannot be classified into structural groups should play important roles in brain functions, though their structures have hardly been investigated,“ say Mizutani and co.
That points to some interesting work ahead, perhaps with shorter-wavelength x-rays that produce higher-resolution data.
However, the extra data will not be easy to handle, given that the current batch required so much work. “The reconstruction of [a higher-resolution] brain network appears to be prohibitively expensive in terms of human workload,” say Mizutani and co.
The data analysis is a significant bottleneck, and better automated model-building techniques are desperately needed. A clear opportunity for computer scientists with a bit of time on their hands.
Ref: arxiv.org/abs/1609.02261 : Three-Dimensional Network of Drosophila Brain Hemisphere
Couldn't make it to EmTech Next to meet experts in AI, Robotics and the Economy?Go behind the scenes and check out our video | <urn:uuid:730cb0c7-2c61-4573-9aea-bc16e873eb1d> | 3.390625 | 1,177 | News Article | Science & Tech. | 51.638075 | 95,549,533 |
Professor Ana Wünsch Blanco has presented her PhD, at the Public University of Navarre, on the application of molecular technologies in the identification and enhancement of the cherry fruit tree.
The application of molecular technologies in the identification and enhancement of the cherry tree is not something new. In fact, the varietal identification of fruit species has been accompanied, in the past few years, by the appearance of DNA markers. This has enabled an investigation of the genome of each variety, independently of the state of development and the phenological state of the tree.
Other research has used these techniques for the identification of peach trees. The significance of the study in the cherry tree arises from the fact that this is one of the economically important stone-fruit species and, moreover, Spain is one of the most important world producers of this fruit. However, this importance is not reflected in the exhaustive studies on the identification of genotypes of the different varieties of the species.
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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A Numerical Simulation of Multiple Vortices
It often occurs that tornadoes contain smaller subsidiary vortices which revolve about the tornado, which in turn, rotate in the same sense as the tornado (see FUJITA, 1970; FORBES, 1978). This phenomenon goes by various names (“suction vortices”, “satellite vortices”, and “secondary vortices”), however, for this work we follow CHURCH et al. (1979) and refer to the multiple vortex phenomenon (MVP). So, when we speak of the MVP we refer to that type of “suction vortex” which FUJITA (1976) has termed the “orbiting vortex”. That the MVP may be more than a minor detail of the tornadic flow is suggested by damage surveys which indicate the most intense destruction of life and property is associated with cycloidal paths which FUJITA has termed “suction swaths”. As with the tornado, very little is known about the internal circulation of the MVP. Photogrametric and ground survey data are inconclusive on such important questions as to i) what maximum wind speed is achieved by the tornado and ii) the relation between this and the MVP. MVs are clearly visible in photographs but it is extremely difficult to infer actual flow patterns.
KeywordsTangential Velocity Axisymmetric Flow Nuclear Regulatory Commission Vorticity Vector Swirl Ratio
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“What we may be detecting is the start of one of these large eruptive events that – if it ever happens – could cause very massive destruction on Earth,” says seismologist Michael Thorne, the study’s principal author and an assistant professor of geology and geophysics at the University of Utah.
Michael S. Thorne, University of Utah.
This map shows Earth’s surface superimposed on a depiction of what a new University of Utah study indicates is happening 1,800 miles deep at the boundary between Earth’s warm, rocky mantle and its liquid outer core. Using seismic waves the probe Earth’s deep interior, seismologist Michael Thorne found evidence that two continent-sized piles of rock are colliding as they move atop the core. The merger process isn’t yet complete, so there is a depression or hole between the merging piles. But in that hole, a Florida-sized blob of partly molten rock – called a “mega ultra low velocity zone” – is forming from the collision of smaller blobs on the edges of the continent-sized piles. Thorne believe this process is the beginning stage of massive volcanic eruptions that won’t occur for another 100 million to 2100 million years.
Since the early 1990s, scientists have known of the existence of two continent-sized “thermochemical piles” sitting atop Earth’s core and beneath most of Earth’s volcanic hotspots – one under much of the South Pacific and extending up to 20 degrees north latitude, and the other under volcanically active Africa.
Using the highest-resolution method yet to make seismic images of the core-mantle boundary, Thorne and colleagues found evidence the pile under the Pacific actually is the result of an ongoing collision between two or more piles. Where they are merging is a spongy blob of partly molten rock the size of Florida, Wisconsin or Missouri beneath the volcanically active Samoan hotspot.
The study’s computer simulations “show that when these piles merge together, they may trigger the earliest stages of a massive plume eruption,” Thorne says.
Thorne conducted the new study with Allen McNamara and Edward Garnero of Arizona State University, and Gunnar Jahnke and Heiner Igel of the University of Munich. The National Science Foundation funded the research.
Probing the Deep Earth with Seismic Waves
Seismic imaging uses earthquake waves to make images of Earth’s interior somewhat like X-rays make CT scan pictures of the inside of the human body.
The new study assembled the largest set of data ever used to map the lower mantle in the Pacific region by using 4,221seismograms from hundreds of seismometers around the world that detected 51 deep earthquakes originating more than 60 miles under the surface.
Thorne and colleagues looked for secondary earthquake shear waves known as S-waves that travel through much of the Earth, hitting the core, and then convert to primary compressional waves or P-waves as they travel across the top of the core. Then they convert back to S-waves as they re-enter the mantle and then reach seismometers. Thorne says the short bursts of P-wave energy are very sensitive to detecting variations in the rock at the core-mantle boundary.
Thorne performed 200 days of supercomputer simulations at the University of Utah’s Center for High Performance Computing. He simulated hundreds of possible shapes of the continent-sized piles and state-sized blobs until he found the shapes that could best explain the seismic wave patterns that were observed.
A Look at the Core-Mantle Boundary
The new study provided an unusual look at one of the most remote parts of the Earth, located about 1,800 miles beneath the surface: the boundary between the planet’s molten outer core and its warm mantle rock, which has convection movement that has been compared with a conveyor belt or slowly boiling tomato soup. (Tectonic plates of Earth’s crust and uppermost mantle drift atop the warmer, convecting lower mantle.)
“We did hundreds of simulations for lots of different variations of what the Earth might look like at the core-mantle boundary – the most simulations anybody has ever done to look at the core-mantle boundary structure,” Thorne says
At some places where oceanic and continental tectonic plates collide – such as offshore from the Pacific Northwest to Alaska – the seafloor plate dives or “subducts” beneath the continent and plunges slowly into the mantle. Thorne suspects subducting plates ultimately fall deep enough to help push the piles around on Earth’s core.
Whether hotspots originate at the core-mantle boundary or at shallower depths has been debated for decades.
But in the 1990s, geophysicists found evidence for the continent-size thermochemical piles beneath Africa and the Pacific. These are known technically as LLSVPs, or “large low shear velocity provinces,” because seismic shear waves passing through them move 5 percent slower that through surrounding mantle rock. That suggests they have a different composition and-or temperature than the surrounding mantle.
Previous studies also have observed smaller blobs of rock, measuring perhaps 60-by-60 miles on the edges of the continent-sized masses. Seismic shear waves move as much as 45 percent slower through these blobs – known technically as ULVZs or “ultra low velocity zones” – indicating they may be spongy and partly molten.
Thorne says his analysis of seismic waves passing through the core-mantle boundary reveals the Pacific pile really represents two or more continent-sized piles slowly sliding atop the core and colliding so that partly molten blobs on their edges are merging into the largest such blob or ULVZ ever observed – roughly the size of Florida.
“My study might be the first to show actual seismic evidence that the piles are moving,” he says. “People who have done previous simulations have suggested this. They are sitting atop the core and getting pushed around by overlying mantle forces like subduction. They move around on the core somewhat like continental plates drift at Earth’s surface.”
Thorne says the merging LLSVP piles are each about 1,800 miles diameter, forming a single pile some 3,600 miles wide from east to west and stretching across Earth’s core beneath an area from Australia almost to South America. Two blobs, or ULVZs, on the piles’ edges merged to form a new blob that is perhaps 6 to 10 miles thick and covers an area about 500 miles long and 150 miles wide, about the area of Florida or “eight to 10 times larger than any ULVZs we observed before,” Thorne says.
Because the larger piles haven’t fully merged, seismic imaging shows there is a depression or “hole” between them, and the Florida-sized blob is forming there as smaller UVLZs merge in the hole.
“We are actually seeing that these piles are being shoved around,” Thorne says. “If hotspots actually are generated near the core-mantle boundary, where they are being generated seems related to where these piles and ULVZs are. So if we are pushing these piles around, we also are pushing around where hotspot volcanism may occur.”
Warmer rock is less dense than cooler rock. Thorne says that where the ULVZ blobs form seems to be related to where the hot rock starts convecting upward to begin the long, slow process of forming a plume that eventually causes massive eruptions.University of Utah Communications
Lee Siegel | Newswise
New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz
Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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12.07.2018 | Event News
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Genetic Basis of Petunia Variation Uncovered
News Jun 10, 2016
Petunias come in many different varieties, which makes them popular bedding plants that appear in gardens and terraces during May and June. This variation is found not only in the petunias available at garden centers, but also in wild petunias. All of these different petunia-types are often pollinated by different insects and birds. Some are attracted to purple flowers, others to white flowers. Some fit into the smallest flowers, others can reach the nectar at the end of the long perianth.
A large international team of researchers, including scientists from Wageningen University, have now sequenced the entire genome of two different wild petunia species, and published this in the important scientific journal Nature Plants. The sequences have shown, that the regions of DNA that contains the genes responsible for the colour and shape of flowers is very variable between the two species of petunia. You could consider this section of DNA as a "hotspot" of genetic diversity compared to other less variable regions .
The petunias available at garden centers are mostly derived from a hybridization event (or genetic cross) between two wild varieties of petunia: Petunia axillaris and Petunia inflata. The hybrid petunia is, very appropriately, named Petunia hybrida. Over the years, many different varieties of petunia were created by further crossings between these hybrids and by the selection of particular desirable characterisitcs. A significantly larger number of genes from the white Petunia axillariswere found in the DNA of Petunia hybrida as compared to the number of genes from the purple Petunia inflata. The researchers state that this has something to do with the white-coloured flower of this species. The other flower colours probably show themselves more easily if plant breeders make use of the white variety in their breeding programmes.
According to the researchers, Petunia axillaris is the evolutionary descendant of an ancestor that strongly resembled Petunia inflata. Theaxillaris-variety was the result of a mutation in the DNA that stopped the plant from producing the purple colouration. More or less at the same time, evolution resulted in the perfume of the plant to become stronger. This made the axillaris plants more attractive to moths, while the original inflata flowers were the favourite of bees.
Paper in Nature Plants
The paper in Nature Plants also shows that petunia is an excellent model system for further plant research. The plants are easy to grow, quickly produce a new generation, and mutations are easily produced and made visible - especially in the flowers. Petunia is also a member of the Solanaceae family, which includes important food crops such as tomatoes and potatoes. Because these plant species are related, researchers and plant breeders are now able to further investigate the functions of genes in the DNA of tomatoes and potatoes as a result of the mapped DNA of petunia.
Many different groups contributed to the unravelling of the petunia-DNA, each with their own interest in petunias. The Biosystematics group at Wageningen looked for 'traces' of duplication or triplication of the whole genome (all the DNA). They found evidence for a DNA-triplication that was also found in tomatoes, and that is regarded as Solanaceae family-specific. However, not all the same genes were lost in tomato or potato that were lost in petunia from a their common shared ancestor during the last 30 million years of evolution. Thus, much can be learned about how tomatoes and petunias came to be different.
MiRNAs in petunia
Together with the Plant Genetics group of the Radboud University, Nijmegen, the researchers also looked at small RNAs (microRNAs, miRNAs) in petunia. MiRNAs are involved in controlling the activity of genes, particularly during the development of plants. They first determined which miRNAs were present in flower buds and then mapped the corresponding genes in the petunia DNA. The DNA sequences revealed that Petunia axillaris and Petunia inflata have many the same genes for miRNAs. This means that these genes already existed from before Petunia axillaris evolved from a Petunia inflata-like ancestor. Such genes that stay the same over a long period generally concern genes with an important function.
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By looking for microorganism's protective shield, specifically the genes that can make it, a team discovered a new and potentially highly effective type of weed killer. This finding could lead to the first new class of commercial herbicides in more than 30 years.READ MORE | <urn:uuid:ade3a38d-bc63-46cc-af7b-38b5e34af122> | 3.546875 | 971 | News Article | Science & Tech. | 27.096109 | 95,549,631 |
Gears. A power point presentation by Student Name. Definition. A wheel with teeth that interlocks with another gear. http://www.webthing.net/settingsun/. Definition. There are two kinds of gears:. ~driver gears. ~follower gears. Gears in Everyday Life.
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A power point presentation by Student Name.
A wheel with teeth that interlocks with another gear.
There are two kinds of gears:
You can find gears in almost anything mechanical that moves. Here are some examples:
~ Car motors and transmissions
This is the MA formula :
MA=radius of driver gear
radius of follower gear
Gears give you force or speed advantages.
~For a speed advantage,the driver gear is bigger than the follower gear.
~The formula for a speed advantage in gears is
SR= # of teeth on driver gear
# of teeth on follower gear
Bob turns a gear that has a radius of 10 cm.
If the follower gear has a radius of 5cm, what is the mechanical advantage of the two gears?
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Stars and Telescopes Essay Sample
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Introduction of TOPIC
Telescopes are considered to be an instrument that makes distant objects to appear closer, (Northwestern, 2012). These instruments have assisted scientists and astronomers in their studies of the universe. With the use of a telescope the studies have changed and become easier to study. This paper will provide information on how the telescope has changed the views of the universe, designs of telescopes, ground-based telescopes, strengths and weaknesses of the location of the telescope, different frequencies of light, and the wavelengths of a telescope. Studies of the universe occurred before the telescope was invented, but was much harder. Today, the telescope has assisted in the many discoveries of the universe. Without a telescope, many of these discoveries may have not been possible.
The telescope has become a main instrument and icon in the world of science. The telescope has opened up opportunities to scientists than in the past, improving the studies and discoveries. Telescopes have changed many views of the universe. The first view that was changed is that the Earth is not the center of the universe. The telescope allows viewing of mountains and craters of the moon, asteroids, new planets, etc. (NASA, 2010). The telescope has also allowed scientists to properly measure the speed of light and to understand the light of st
ars and Sun, (NASA, 2010). While telescopes have opened up a new
A reflecting telescope uses a curved primary mirror to gather light, reflecting the gathered light to a secondary mirror that lies in front of it. The gathered light or image can then be seen through the eye piece, (Bennett, Donahue, Schneider & Voit, 2010). Reflecting telescopes are great when viewing deep sky objects such galaxies, star clusters, etc. These telescopes create bright images, and are usually compact or portable. Reflecting telescopes have multiple strengths, but also have weaknesses. This type of telescope is not useful during terrestrial viewings, more care and maintenance needed, dust and air can negatively affect the images provided through the lens, (Telescope, 2013).
The last design, catadioptric telescopes are a combination of mirrors and lenses. The mirrors and lenses fold the optics and form an image. This type of design has strengths in viewing lunar, planetary, binary and terrestrial observations, and elimination of air current affecting images. This design has a weakness of light loss, due to the secondary mirror obstruction, (Telescopes, 2013).
Ground-based telescopes are used to observe and study exoplanets. | <urn:uuid:87897dbe-9dfd-4c99-ab43-a202fc9dfc32> | 2.859375 | 571 | Product Page | Science & Tech. | 34.901536 | 95,549,649 |
Huge waves that struck Reunion Island and coastlines across Indonesia earlier this month all originated from the same storm that occurred south of Cape Town, South Africa, and were tracked across the entire Indian Ocean for some 10 000 kilometres over a nine-day period by ESA's Envisat satellite.
Waves reaching up to 11 metres devastated France's Reunion Island in the Indian Ocean when it slammed into the southern port of Saint Pierre on 12 May. Six days later waves created from the same storm measuring as high as seven metres began crashing into Indonesia coastlines from Sumatra to Bali, killing at least one person and causing some 1200 people to flee their homes.
Dr Bertrand Chapron of IFREMER, the French Research Institute for Exploitation of the Sea, and Dr Fabrice Collard of France's BOOST Technologies in Brest located and tracked the swells using standard processed Synthetic Aperture Radar (SAR) ESA Wave Mode products, as shown in the animation above.
"The extreme swell systems originated from the same storm, which moved rapidly and had two main strong wind periods," Chapron said. "As illustrated in the animation, the resulting waves were organised into two main swell systems that followed each other across the entire Indian Ocean, hitting Reunion Island, Mauritius, Australia and Indonesia."
According to the Reuters news agency, no official warning about the huge waves that hit Indonesia were issued. Although the waves that hit Reunion Island were forecasted, their intensity was predicted to be 20 to 30% below measurements, Collard explained.
"Although swells are still surprise factors, these particular swells were created by natural events so they could be tracked," Chapron said. "By using the SAR Wave Mode product, we can locate and systematically track swells globally, making it possible to put a network of early warning systems in place in the near future."
"Because of its unique capacity to restitute wavelength and directional information of the propagation of swells, the SAR instrument is about to bring a remarkable contribution to the monitoring of energetic wave systems," Collard said.
Chapron and Collard are working on a global swell-tracking project, which was presented for the first time at the Envisat Symposium held in Montreux, Switzerland, from 23 to 27 April 2007, using the Advanced Synthetic Aperture Radar (ASAR) aboard Envisat to follow these waves in order to refine their propagation paths and determine their arrival times and intensities.
Once in place, this system will be the equivalent of deploying a global network of virtual buoys that are able to detect and track large swell systems carrying large energy from all available remote sensing measurements of waves, such as SAR and radar altimetry.
Each virtual buoy will have the capacity to detect and measure the wavelength and the direction of propagation as well as the height of the swell systems crossing the oceans, complementing the sea forecast models used by weather centres and allowing alarms to be raised a few hours before these devastating swells hit coasts.
Storms are capable of generating waves of different wavelengths that travel in several directions upon leaving the storm system, with the longest wavelengths travelling the fastest. As these waves cross open seas, they can accumulate energy at precise locations and become very dangerous for marine safety.
In addition, wave systems slow down as they approach the coastline, and individual waves increase to reach at least two times the mean average of their initial wave height. For instance, a 5-metre significant wave height system can hit the coast with the height of 10 metres.
Today, the ASAR Wave Mode acquires 10 by 5 km small images, or 'imagettes', of the sea surface every 100 km along the satellite orbit. These small 'imagettes' are then mathematically transformed into averaged-out breakdowns of wave energy and direction, called ocean-wave spectra, which ESA makes available to scientists and weather centres.
As part of the Global Monitoring for Environment and Security (GMES), a joint initiative of the European Commission and ESA, the space agency has undertaken the development of Sentinel-1, a European polar-orbiting satellite system for the continuation of SAR operational applications.
The Sentinel-1 SAR instrument will also have a dedicated enhanced Wave Mode capability to double the present ASAR Envisat Wave Mode samplings, to improve the actual demonstrations for a Near Real Time tracking and forecasting of swell for European users.
ESA and IFREMER will sponsor an ocean wave data user workshop at IFREMER in Brest, France, on 20 and 21 September 2007 that will address and capture user requirements for a possible future wave data service.
In January 2008, ESA will host its second SAR oceanography workshop, SEASAR 2008, entitled "Advances in SAR Oceanography from Envisat and ERS missions," at ESRIN, ESA's Earth Observation centre, in Frascati, Italy. | <urn:uuid:d55ba1d5-0b29-40a0-a8c4-c0d209822b61> | 3.03125 | 1,005 | News (Org.) | Science & Tech. | 19.813308 | 95,549,654 |
These waves can be configured to add or subtract, or interfere, with one another in an interferometer-an instrument that is used on airplanes to measure very small changes in rotation. Since global positioning system (GPS) location information is not available everywhere, airplanes still use inertial navigation systems founded on laser-based interferometers, even though their accuracy drifts over time. Kasevich's "atomic interferometer" may form the basis of a next-generation navigation system that gauges the airplane's location much more accurately.
"Navigation problems-how to get from point A to point B-tell us about space-time," says Kasevich, a professor in the departments of Physics and Applied Physics who will speak about atomic sensors Feb. 17 in San Francisco at the annual meeting of the American Association for the Advancement of Science (AAAS). "When we build these de Broglie wave navigation sensors, we're also building sensors that can test these fundamental laws about space-time."
Kasevich's atomic interferometer also is a sensitive detector of gravity-by far the weakest of the four fundamental forces of physics. Kasevich and his research group are using the interferometer to measure the gravitational constant, G, to greater precision than has ever been reached in the more than three centuries since Isaac Newton put forward his law of universal gravitation. Moreover, Kasevich is putting another physics legend to the test in ongoing research of Einstein's century-old principle of equivalence, which states it is impossible to tell the difference between the acceleration of an object due to gravity and the acceleration of its frame of reference.
The panel in which Kasevich is speaking is titled "What's Hot in Cold." Other participants include Tom Shachtman, author of the nonfiction book Absolute Zero and the Conquest of Cold, as well as physicists Heather Lewandowski of the University of Colorado-Boulder; Steven M. Girvin of Yale University; Richard Packard of the University of California-Berkeley; and Moses Chan of Pennsylvania State University-University Park. They will describe how matter cooled to low temperatures behaves according to the laws of quantum mechanics, which operate quite differently from the familiar world of classical physics. Whether gas, liquid or solid, each system in this ultracool regime proves to be a rich trove of new physics.
Interferometry-old and new
Navigation technology inspired Kasevich's atomic sensors. Airplanes monitor their attitude with ring-laser gyroscopes, which use interferometry to detect rotation. In conventional interferometers, a single-wavelength beam from a laser is split into two paths and later recombined so that the final wave exhibits a characteristic pattern. This interference pattern will differ depending upon the differences in paths traveled by the two split waves. If the paths are identical, they will recombine as the original wave. But as the airplane with its gyroscope turns, rotation of the interferometer inside changes one split wave's path relative to the other, and the difference causes the recombined wave to partially dim. With a large enough shift between the split paths, the recombined wave can vanish entirely in what is known as total destructive interference.
Kasevich's team applies this principle using not laser light but cesium atoms. As an atom is cooled to very low temperatures, below minus-459 F, its velocity slows to zero, and-due to the principles of quantum mechanics-the atom begins to behave like a wave, just as in Louis de Broglie's Nobel Prize-winning prediction of 1923. The colder and therefore slower the cesium atom becomes, the longer its wavelength. Ultimately these wave-like atoms can get so cold that they reach wavelengths comparable to visible light. And they can be split and made to recombine just as in a conventional laser interferometer, yielding the atomic interferometer.
The most bizarre property of the atomic interferometer, Kasevich says, is that total destructive interference makes atoms seem to disappear.
"Nature lets me take this atom, split it in half and bring it back together," he says. "The cesium atom is in two places at once, and nature lets it do that. You can't do that with marbles."
But matter is neither created nor destroyed. "We're manipulating the probability of where we find the matter in space," Kasevich clarifies.
Substituting an atomic interferometer for a conventional one inside an airplane's ring-laser gyroscope would yield an atomic gyroscope. The atomic gyroscope, if it could be produced at a portable size, would be a desirable replacement for ring-laser gyroscopes because the older technology loses accuracy in gauging the airplane's location to the tune of about 1 mile (1852 meters) per hour. By comparison, an atomic sensor could lead to drifts of around 16 feet (5 meters) per hour-three one-thousandths of the error.
G attracts Kasevich's interest
Besides their potential for improving navigation accuracy, Kasevich's atomic interferometers or sensors also are sensitive enough to detect changes in the split wave induced by gravity. The level of sensitivity is fine enough to be able to detect changes in gravity at levels below one part per billion. Gravity is the longest known of all fundamental physical forces. Kasevich's group continues to work to refine the atomic sensors in hopes of measuring Newton's gravitational constant G beyond the level of precision at which it has been measured-a figure that has not improved much since British natural philosopher Henry Cavendish published the first measurement more than two centuries ago.
"We want to add our voice to the chorus of 'What is G really?"' says Kasevich.
Another mystery that ultracold atoms may help solve is Einstein's equivalence principle, which to date hasn't been proved or refuted. In his equivalence principle, Einstein asserted the gravitation experienced while standing on a massive body, such as Earth, is the same as the pseudo-force experienced by an observer in an accelerated frame of reference. Just like a spinning dancer's body causes her skirt to twirl, the revolving Earth drags space and time around it, providing the frame of reference from which we determine positions and movements.
An ongoing experiment to test this principle is set up in a 10-meter-tall tube installed in the basement of the Varian Physics Building at Stanford. It employs isotopes-atoms of a chemical element with the same atomic number and nearly identical chemical behavior but with different atomic masses. Two different isotopes of rubidium are cooled to ultralow temperature and released into free fall. The wave-like atoms fall very slowly, "like releasing a fistful of sand," Kasevich says. If the two isotopes, which have slightly different masses, accelerate at differing rates as measured with atomic interferometry, this means the principle of equivalence fails.
The implications are profound, Kasevich says. "If Einstein's equivalence principle doesn't hold, that means that we would have to rethink the law of physics at a very basic level."
Dawn Levy | EurekAlert!
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Materials Sciences
18.07.2018 | Life Sciences
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Breaking the 100-MeV barrier for proton acceleration will help elucidate fundamental physics and advance practical applications from inertial confinement fusion to tumour therapy. Herein we propose a novel concept of bubble implosions. A bubble implosion combines micro-bubbles and ultraintense laser pulses of 1020–1022 W cm−2 to generate ultrahigh fields and relativistic protons. The bubble wall protons undergo volumetric acceleration toward the centre due to the spherically symmetric Coulomb force and the innermost protons accumulate at the centre with a density comparable to the interior of a white dwarf. Then an unprecedentedly high electric field is formed, which produces an energetic proton flash. Three-dimensional particle simulations confirm the robustness of Coulomb-imploded bubbles, which behave as nano-pulsars with repeated implosions and explosions to emit protons. Current technologies should be sufficient to experimentally verify concept of bubble implosions.
Ion acceleration by intense lasers has been studied because the interaction between ultraintense ultrashort laser pulses and solid matter can produce energetic ions. Such ions have potential in numerous applications such as tumour therapy1,2, radiography of dense targets3, proton-driven inertial confinement fusion4, and injection into conventional accelerators5. Additionally, the generation of high-energy protons is a goal in fields such as high-energy-density physics and astrophysics. The present paper provides a novel fundamental idea shedding light on an unexplored approach to generate unprecedentedly high fields and ion densities as well as the accelerated ion energy, that has never been proposed earlier.
Several schemes have produced energetic protons using high power lasers. Examples include target normal sheath acceleration6,7,8,9, Coulomb explosion10,11,12,13,14,15,16, radiation pressure acceleration17,18,19, breakout afterburner acceleration20,21, magnetic vortex acceleration22,23, and collisionless shock acceleration24,25,26. Depending on the applied laser intensity, these schemes can generate protons with energies on the order of 10–100 MeV under applied laser intensities of 1020–1022 W cm−2. To date, only higher laser intensities have been considered to achieve higher proton energies.
Here we propose a new concept - bubble implosion. Suppose that spherical bubbles with radii of the order of R0 0.1–10 μm are artificially contained in a uniform solid target, which is assumed in this paper to be pure hydrogen just for simplicity. When irradiating the target by ultraintense femtosecond laser pulse with an intensity of IL 1020–1022 W cm−2, hot electrons with temperature of Te 10–100 MeV are generated according to the Ponderomotive scaling6. The hot electrons run around in the target to ionise the atoms to the ionization state Z = 1 almost instantaneously with its initial solid density cm−3 being kept constant. The hot electrons fill the bubbles in a very short period, the characteristic time of which is a few fsec (Fig. 1(a)), where c is the speed of light. It should be noted that the high mobility of hot electrons often result in unwelcome energy dissipation and entropy increase in many applications. However, in the present scheme, such features of electrons play the crucial role to provide super high uniformity of the implosion and an ultrahigh field.
Because of the electrons flying in the bubble, the ions on the bubble surface “feel” strong electrostatic (Coulomb) force and begin volumetric implosion toward the bubble centre as illustrated in Fig. 1(b). The innermost ions continue to implode until they are unprecedentedly compressed to a nanometer scale such that their radial inward motion is stopped by the resulting outward electric field. Upon collapse of the bubble, the innermost ions “find” that their following ions just behind them have built up an extraordinary steep slope of Coulomb potential. Then they slide down the slope with resulting energies many times higher than the energy gained during the implosion. Figure 1(c) illustrates the envisioned mechanism with the main events depicted on the same image, i.e., laser illumination, hot electron spread, bubble implosion, and proton flash. One might expect that such an “anomalous” ion acceleration may occur in laser interaction with porous materials like foam27. However, as apparently understood from a simple model given below, the special characteristics of bubble implosion can be realized under high symmetry of the hollow and surrounding nanostructures.
Phenomena such as converging shock waves28 and sonoluminescence29 are similar to a bubble implosion. Shock waves are observed in many branches of physics. Although sonoluminescence is a relatively new phenomenon in the acoustics field, Lord Rayleigh proposed the basic idea (contraction of a water bubble) over a century ago30. The behaviour of bubble implosions reported in this study remarkably differs. Extremely high temperatures and low densities characterise the physical states of collapsing converging waves at the centre in shock waves and sonoluminescence. By contrast, extremely high densities and practically zero temperatures for protons characterise bubble implosions.
It should be also noted that Nakamura et al.31,32 have reported another seemingly similar phenomenon - “Coulomb implosion”. However, the two implosions are phenomenologically different from each other. The Coulomb implosion occurs for negative ions with a much smaller fraction than the bulk positive ions, that are expanding via Coulomb explosion after the most electrons are blown off by an intense laser. On the other hand, the bubble implosion is driven by the bubble-filled electrons. Because of the essential difference in the electrons role, the bubble implosion results in, for example, an overwhelmingly higher compressed density of ions than Coulomb implosion.
We postulate below that the total volume of bubbles, Vb, is much smaller than the volume of a solid matter containing the bubbles, Vs. In other words, the bubble disoccupancy α is close to unity, i.e., , where R1 stands for a virtual radius of a spherical solid assigned to a single bubble (Fig. 1(a), dashed circle). Also we postulate that the electron temperature Te is so high that the electrons distribute uniformly over the whole region of the target. This isotropic assumption of electron distribution will be demonstrated in the PIC simulation given later. The total electric charge integrated from the centre to an arbitrary radius r, i.e., with e being the electron charge, and the local electric field, Ef(r), are related by Gauss’s law in the form, Ef(r) = Q(r)/r2. The whole ions thus begin to accelerate inward according to the electric field. The maximum implosion velocity is achieved when they reach at around the centre, which corresponds to the energy done by the electric field, , given by
where is the total electron number contained in the initial bubble with being the average electron density in the bubble. Note that cm−3 is here employed as a reference value, which is actually in the same order as those obtained in numerical simulations discussed later. It is shown below that Ne0 is the one and only crucial “extensive” variable, essentially differentiating the present scheme from the aforementioned schemes.
To extract the salient features, we conducted 1D simulations of the bubble implosion. For simplicity, the electrons are assumed to obey the Boltzmann relation, because the electron mass is significantly smaller than an ion. The electrons are then described by Poisson-Boltzmann (P-B) equation, , where ϕ is the electric potential and nec is the temporal electron density at the centre. The P-B equation is furthermore simplified as a function of the dimensionless parameter Λ ≡ R0/λDe, where is the Debye length. The parameter Λ characterises to which extent the bubble is filled with the electrons. As a function of Λ, the P-B equation is numerically solved to give ϕ(r) and thus ne(r) under the appropriate boundary conditions. The electric potential profile is thus determined at every time step according to the ion motion in the field.
The ions are computed by particle-in-cell (PIC) method. Furthermore, only in the very limited central volume for r 0.02R0, the ion motion is calculated based on the scheme of molecular dynamic (MD) simulation. This is because the tiny central region is the key domain where an ultrahigh field is formed to generate high energy protons. Therefore one needs to precisely evaluate the protons dynamics instead of using the averaged field prescribed by the PIC method. In the present 1D simulation in spherical geometry, we employed 2000 fixed grids, and 2 × 104 pseudoparticles.
Figure 2(a,b) shows the initial profiles for the electron density ne(r) and the electric field, respectively, obtained for different values of Λ and a fixed initial ion density profile normalised by ni0 under R1/R0 = 2. The electron profiles for Λ 1 are rather flat over the entire domain, while they conspicuously reduce in the bubble with increasing Λ(2). It is convenient to normalize time t and use the dimensionless quantity ωpi0t instead, where is the ion plasma frequency and mi is the ion mass. As a reference, for solid density protons with ni0 = 5 × 1022 cm−3.
Figure 2(c) shows the ion trajectories for the entire time region under the bubble conditions of R1/R0 = 2 and Λ = 0.5. The black curves correspond to initial radii with a constant increment of Δr = 0.04R0, while the blue curves subdivide the innermost segment to better resolve the implosion dynamics. The labels along the time axis, A - H, are to compare other physical quantities in subsequent figures. Figure 2(d) shows a zoom-in of the rectangular in Fig. 2(c). Until time D, all of the ion trajectories remain laminar, so that one curve does not intersect another. However, upon the collapse (time E), the innermost trajectory is strongly ejected radially outwards and this is the phenomenon that we call the proton flash. In Fig. 2(d), the innermost seven trajectories in blue represent flashed protons and they behave quite differently from the other trajectories. These trajectories sharply cut across the other trajectories, confirming that the flashed protons quickly slide down a Coulomb potential that can be effectively viewed as quasi-static. These “runaway” protons are emitted from a very small volume with r 0.05R0 due to an explosive acceleration under the ultrahigh electric field that is generated by the accumulated proton core at the centre.
Figure 3(a) shows the velocity evolution of the flashed protons and the surrounding protons, normalised by the maximum implosion velocity vmi. The blue and black curves correspond to those in Fig. 2(d). Upon the collapse (times D - F), the velocity of the flashed protons drastically increases, exceeding the maximum implosion velocity by a factor of 2.0–2.5, which are simply squared to give corresponding energy amplification by a factor of 4–6. This energy amplification for the flashed protons is due to their sliding down the steep Coulomb potential slope. The innermost protons are the first ones to be reflected near the centre. The dynamics of the other protons that follow and that are located a bit further outwards is similar, but the expulsion is slightly delayed and the resulting energy amplification factor is smaller.
Figure 3(b) shows snapshots of the proton velocity as a function of radius for times A - H in Fig. 2(c). For practical laser and target parameters, the proton flash occurs over a very short time interval (0.5 fsec) and a very small volume ( a few nm) corresponding to times D - F. The flashed protons have a much higher velocity than surrounding bulk protons, as can be seen in snapshots G and H. It should be noted that, at such later times, a snowplow-like two-stream-structure is formed. The difference in velocity between the two streams is of the order of vmi. In this simulation, the total number of flashed protons is found to be roughly 10−2 Ne0.
We developed a simple model to understand what determines the fraction of the flashed protons and the corresponding energy amplification factor, assuming and . In other words, the electrons maintain an almost uniform density in the entire system at . Motivated by the already presented simulation results, we assume that the protons keep their order in space without overtaking each other (or nonbreaking) until the moment of the collapse. Note that this nonbreaking assumption of ion flow was also employed in refs31,32. Under these assumptions, the equation of motion for a proton prior to the collapse, , that was located at r(t = 0) = r0, is given by
where . Physically the first and the second terms on the right-hand side of Eq. (2) indicate that the Coulomb force is due to the protons and the electrons contained in the volume at radii smaller than r(t), respectively. The maximum implosion speed of a proton at an initial position r0 occurs at r = r1 when . Analytical integration of Eq. (2) provides the velocity of a proton, , as a function of position r as
Equation (3) indicates that the maximum implosion speed is achieved by the innermost protons r0 = R0 as they reach the centre. Additionally, a proton with its initial position r0 is halted (v = 0) due to the Coulomb repulsion at . Using for r0 ≈ R0 derived from above analysis, the mass conservation is reduced to give the density profile of the innermost protons upon the collapse as
where the subscript “2” is dropped for simplicity.
Figure 3(c) shows how the proton density evolves in time in the presented 1D simulation. Upon the collapse (time E), the density in the innermost grid exceeds the original density by five orders of magnitude, with ni/ni0 > 105. This extraordinarily high compression shown in Fig. 3(c) has a power-law dependence, ni ∝ r−2, which agrees with Eq. (4) depicted as the dashed line. It is worth pointing out that, in an agreement with our assumptions, the electron density indeed remains almost flat throughout the whole process due to the high electron mobility. After the proton flash, bulk ions also rebound to expand outward. A salient feature of this stage is the peaked structure in the density profile that is formed on the expanding bubble surface (times F - H).
The ion energy spectrum at time H is shown on double-linear scales (Fig. 3(d)) and double-logarithmic scales (inset). The energy is normalised to the maximum kinetic energy, , defined by Eq. (1). The energy amplification for the flashed protons, , ranges from 3 to 7. The two-humped structure for is attributed to a complex behaviour of the innermost ions as their trajectories overlap upon the collapse.
The minimum radius rmin achieved at the maximum compression is determined by the dynamics of the innermost ions. The compression stops when the maximum kinetic energy, , gained during the implosion is converted into the potential energy, . The total kinetic energy of the innermost ions is , where Na is the total number of these ions. Considering that the characteristic interatomic distance on the initial bubble surface is , we find . Meanwhile, the potential energy is . Using the energy balance, , we find . For example, this gives rmin 0.81 nm for ni0 = 5 × 1022 cm−3. It should be noted that rmin depends only on the initial ion density ni0, and not the initial radius R0 or the ionization state Z. At r = rmin, the maximum ion density nmax is given with the help of Eq. (4) as
The maximum radius where the scaling (4) is applicable can be roughly estimated by solving, , to give . The applicable range for the derived density scaling is then approximately defined by rmin r rmax. The numerical factors in the expressions for rmin and rmax are not significant, because the energy amplification factor that is derived below is only logarithmically sensitive to rmin and rmax. For example, for R0 = 2 μm and cm−3, Eq. (5) gives nmax/ni0 ≈ 2 × 105, which is comparable to interior densities of a white dwarf. Note that, under such ultrahigh densities of hydrogen isotopes, pycnonuclear reaction can be discussed as a potential application33.
Using the compressed density profile given by Eq. (4), we can now find the corresponding profile of the radial electric field Ef that causes the proton flash. The centrally condensed positive charge, , readily yields Ef(r) = Q(r)/r2 = Q0/2R0r, where Q0 = Ne0e is the total electron charge contained in the initial bubble. In a Coulomb imploded core, the electric field is higher as the radius decreases. Here the electron contribution is neglected when evaluating Q(r) near the centre, because in the highly compressed ion core. These radial dependencies remarkably differ from those for the well-known classical case of a uniformly charged sphere (or Coulomb explosion) with ni(r) = const, i.e., Q ∝ r3 and Ef ∝ r. For example, assuming cm−3, R0 = 2 μm, and r = 1 nm as a characteristic scale of the core, the above scaling for a bubble-imploded core predicts Ef ≈ 6 × 1014 V/m. This value of the electric field is roughly three orders of magnitude higher than the fields observed in current laser-plasma experiments, and six orders of magnitude higher than the maximum accelerating field achieved in the conventional accelerators driven by radio frequency (RF) fields6.
Next we evaluated the energy amplification factor. The maximum kinetic energy of flashed protons corresponds to the Coulomb potential gap that has been built up around the bubble centre when the innermost ions start to expand, i.e., , which is reduced to give the energy amplification factor as
We also estimated the number of highly accelerated protons as flashed protons. For simplicity, flashed protons are considered to be protons exceeding the threshold, which is defined as half maximum energy, i.e., . Using Eqs (4–6), the normalised total number of protons with energies is given by
For example, N1/2/Ne0 = 0.9% for R0 = 2 μm and cm−3, which is close to the 1D simulation result in Fig. 3(d).
To investigate the bubble implosion in more detail, we conducted 3D simulations. This is a distinctly multi-scale problem, since both the spatial and temporal scales of a bubble implosion vary over four orders of magnitude from 1 nm to 10 μm and from 0.01 fsec to 100 fsec, respectively. We used both particle-in-cell (PIC) and molecular dynamics (MD) approaches to tackle this challenging problem. PIC simulations can provide a comprehensive physical picture by treating a lot of particles, but the dynamic range is limited because of the fixed size of the cartesian cells. In contrast, MD simulations can treat the dynamics over a much wider dynamic range, taking all binary collisions into account, but because of that they are limited to a much smaller number of particles. In what follows, we complementarily use PIC and MD simulations to examine global features of the phenomenon and the localized behaviour of the innermost protons during the bubble implosion, respectively.
3D (x, y, z) PIC simulations were conducted with open-source fully relativistic code EPOCH34 using the periodic boundary conditions for particles and fields, while placing the bubble into the middle of the cubic computational domain. This approach simulates having multiple equally spaced bubbles inside the considered heated material. We set the cell sizes at 2 nm, because the key physical events of a bubble implosion occur on a nanometre-scale. The box size must be more than double the diameter of the bubble to ensure a spherically symmetric implosion and to avoid interference from neighbouring bubbles. The computational domain size was 240 × 240 × 240 nm3, while the initial bubble radius was R0 = 60 nm.
Figure 4(a) shows snapshots of the bubble implosion at different times obtained by the 3D-PIC simulation, where the density distributions on the x-y plane are colour-coded. At t = 0, the bubble in the middle of the box is empty. We initialised an otherwise uniform proton plasma composed of hot electrons and cold ions with Te = 1 MeV, Z = 1, and ni0 = ne0 = 3 × 1021 cm−3, from which the period for one cycle is estimated to be Tcyc = 2π/ωpi0 = 87 fsec. The hot electrons quickly fill in the bubble volume and the implosion is launched. After the bubble collapses at t ≈ 45 fsec ≈ (1/2)Tcyc (first flash), the bubble expands and then shrinks again to show a second flash at t ≈ 130 fsec ≈ (3/2)Tcyc and then a third flash. This oscillating behaviour is confirmed by the 1D simulations. The bubble thus behaves as a nano-pulsar, alternating implosions and explosions to periodically emit energetic protons. The highly robust bubble oscillation is attributed to the collective nature of the spherically symmetric Coulomb system. Here it should be noted that the converging flows are generally unstable. As a matter of fact, the azimuthally asymmetric modes growing in time are well seen in Fig. 4(a). This should impose a constraint on the achievable ion energy. Also it should be noted that the square-shaped compressed core in panel 10 is likely to be attributed not only to the physical reason but also to the Cartesian mesh scheme employed in the PIC code. It is however beyond our scope in this paper to discuss in detail how the degraded sphericity of the bubble or the mesh structure affect the bubble implosion performance.
Figure 4(b) shows the time evolution of the proton energy spectrum. The maximum compression of the protons is , which is 2.5 times larger than predicted by Eq. (5). This difference may be because proton convergence to the centre in three-dimensions may have discrepancies in time and space compared to the perfect 1D model. On the first flash, the maximum values of the implosion energy and the reflected proton energy are respectively read off to be 25 keV and 150 keV, and thus the energy amplification factor , which agrees well with the 1D prediction. After the first flash, the maximum proton energy further increases on the successive flashes, though only weakly. Overall, it turns out that the 3D-PIC simulation results and the simple model agree qualitatively.
The isotropic behavior of the electrons assumed in the simple model and the 3D simulation plays a crucial role in the concept of bubble implosion. Meanwhile, illumination of an ultrashort ultraintense laser on matter generally produces extremely violent electromagnetic fields and resultant complex plasma motion. To demonstrate that a symmetric bubble implosion can indeed be achieved under an asymmetric laser-matter interaction circumstance, therefore, we conducted another simulation, which is still primitive but acceptably realistic. Since one needs then wider interaction space than earlier, we conducted 2D (x, y) PIC simulation with the computational domain size of 1200 × 1200 nm2 and the cell size of 1 nm, and thus keeping the total computational size in the same order as in the 3D case. Here it should be noted that cylindrically symmetric bubble (column) implosions can also be discussed in a similar manner to the spherical case, though we do not discuss it in this paper.
Figure 5 shows such a 2D result for a single bubble implosion. The 1st, 2nd, and 3rd row correspond to the ion density n i , the absolute value of the electric field E f (magnified views), and the electron density n e , respectively. The four columns correspond to different observation times, correlated with the laser intensity. In this simulation, a square-shaped target is normally irradiated from four directions by flat laser with the wavelength λ L = 1 μm. The applied laser intensity on each side is given by with the constants I0 = 5 × 1018 W cm−2 and τ L = 20 fsec. At t = 0, the plasma composed of cold electrons and protons with their initial density ni0 = ne0 = 3 × 1022 cm−3 is initiated, while the bubble is set perfect vacuum in the same size as in Fig. 4. The generated hot electron temperature this time is self-consistently computed.
From Fig. 5, it can be seen that the electrons quickly fill the bubble rather uniformly owing to their high mobility and that the electric field around the imploding bubble consequently keeps its fully circular shape to drive the bubble-surface protons toward the center. In contrast to the bubble surface, the electric field with a speckled pattern in the solid is quickly smeared out with time. As a result, at a time immediately after the bubble collapse (see the upper right panel for n i at t 51 fsec), the formation of a nm-sized proton core is indeed observed at the center, where the full width at half maximum (FWHM) of the core profile turned out to be ~4 nm. This is already in the same order as the size of an unit cell. In other words, one needs even higher precision of the simulation to study the core dynamics for more details. Here it should be noted that the fine structures of shock propagation, formed in a Coulomb explosion of nanoscale clusters, were studied with high precision in refs13,14. Moreover, Peano et al.15 studied a collisionless Coulomb explosion using a novel kinetic model to describe the electron dynamics. Their advanced numerical techniques are expected to be useful also for the study of bubble implosion.
Next we conducted 3D-MD simulation to quantitatively investigate the dynamics of the innermost protons, particularly when they converge at the centre. Recall that, in a spherically symmetric Coulomb system, a charged particle with radius r is influenced only by particles contained in the spherical volume with radii smaller than r. Based on this fact, one can simulate the bubble implosion of a single atomic layer without taking the surrounding ions’ influence into account. In the simulation we used Na = 103 pseudoprotons (instead of in a real system), which were initially arranged on a spherical surface at R0 = 1000 nm, while the electrons were treated as a uniform background corresponding to cm−3. In a real system, the electric field produced by the innermost protons should plateau due to the overwhelmingly large number of protons, , because the integrated effect of nonuniformity from all the surface protons is smeared as Na increases in proportion to . In other words, the nonuniformity level of the electric field in the MD simulation with 103 particles is ~300 times larger than that of a real system. Thus, arranging such a small number of protons as uniformly as possible on a surface to mimic a real system is not trivial. To find the best initial configuration of the protons, we employed a self-organising method35, which can achieve a lowest Coulomb potential energy of the surface proton system. The resultant configuration of charged particles provides the most uniform and most smooth self-field.
Figure 6(a) shows snapshots of the imploding particles obtained by the 3D-MD simulation, in which just the hemispherical domains are projected in four boxes with different scales ranging over three orders of magnitude. The original total mass and charge of protons in a real system are kept unchanged with the Na = 103 pseudoparticles. As a result, a single atomic layer can shrink to almost the same radius as that predicted by the simple model, i.e., nm. The radial compression rate is R0/rmin 1000, which is consistent with the result observed in Fig. 3(c). For comparison, the achievable radial compression ratios in other spherical convergent systems are, 30–40 in inertial confinement fusion36 and 100–150 in sonoluminescence29. Hence, even a primitive system with a larger self-field nonuniformity than a real system can be compressed more than 1000 times.
Figure 6(b,c) show the temporal evolutions of the trajectories and the kinetic energies (interpreted for a real proton mass) for randomly sampled pseudoparticles, where the time origin of the horizontal axis is reset at the maximum compression for simplicity. The overlap of the maximum compression with the sample curves confirms the symmetric implosion. Note that the maximum exploding energy (Fig. 6(c)) is limited to twice the maximum imploding energy, which can be explained by the energy conservation law. Upon the maximum compression, when the pseudoparticles halt near their stagnating points, the trajectories become random. It should be noted that, after the maximum compression is achieved, the physical picture given here does not make practical sense, because the innermost protons in the explosion phase interact with the protons just behind them, which is not considered in the current MD simulation.
In summary, we propose a novel concept, bubble implosion, to generate an ultrahigh field to accelerate protons to relativistic energies. A simple model and 1D, 2D, and 3D simulations comprehensively investigate the dynamics of the bubble implosion. This phenomenon is very likely to occur in reality. A stable implosion shrinks to a nanometre size and achieves an ultradense proton core, forming an unprecedentedly high electric field and producing proton flashes. The generation of an ultrahigh field is attributed to spherical convergence to the centre. Moreover, Coulomb-imploded bubbles are robust and behave as nano-pulsars repeating implosion and explosion to emit energetic protons. Although the present paper assumes pure hydrogen targets, a modified scenario should be applicable to other hydrides.
Current laser technology is suitable to experimentally identify bubble implosion by observing proton emissions at relativistic energies, which will be a major breakthrough to crack the 100-MeV barrier. For such experiments, a uniform and well-activated Coulomb field must be created inside the bubbles by laser irradiation of micron-sized bubbles embedded inside a solid target. We have demonstrated in terms of the 2D simulation that a symmetric bubble implosion can be achievable even under a realistic condition of laser-matter interaction. Consequently, the present concept should provide a new platform to elucidate fundamental phenomena in the fields of high-energy-density physics and astrophysics.
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This work was supported by the Japan Society for the Promotion of Science (JSPS). Simulations were performed using the EPOCH code (developed under UK EPSRC Grants No. EP/G054940/1, No. EP/G055165/1, and No. EP/G056803/1) using HPC resources provided by the TACC at the University of Texas and the Comet cluster at the SDSC at the University of California at San Diego. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1548562. One of the authors (M.M.) thanks Prof. Y. Sentoku for a trial simulation. | <urn:uuid:f70a10ba-a4bc-4b1a-aa91-470696aa7f5e> | 2.546875 | 6,722 | Academic Writing | Science & Tech. | 40.680259 | 95,549,656 |
Today, Selenium is viewed as a to a great degree helpful open source structure for programming testing. Selenium accompanies a default test area dialect called Selenese; be that as it may, you can likewise utilize dialects like Java, Ruby, C#, Python, and so on to script a test.
Selenium is a generally utilized open source, compact programming testing structure for web applications. Despite the fact that Selenium accompanies a test area particular dialect (Selenese), other programming dialects (Java, C#, Ruby, Python) can be utilized to script tests also. Tests made in different dialects speak with Selenium through calling strategies in the Selenium Client API. Selenium is in this way customer dialect unbiased.
Because of its capacity to consolidate with various programming dialects, Selenium is the most favored dialect free system.
All associations moving to Selenium for their web application testing face one regular question:
What dialect do we choose to fabricate Selenium based test robotization suites?
How about we begin off by taking a gander at programming dialects overall? Despite the fact that a wide range of dialects exist and new ones are as yet being made, one must note that, approximately 90% of the ideas one learns in a particular dialect are likewise material to totally extraordinary dialects. When one knows about the center nuts and bolts (program configuration, control structures, information structures, and fundamental operation of a programming dialect), creating comparative aptitudes with another dialect just comes down to understanding the linguistic subtleties.
Things being what they are, which dialect would it be a good idea for one to pick? As an individual, the appropriate response is clear: run with what you're most OK with.
Dima Kovalenko, in his book titled Selenium Design Patterns and Best Practices, delineates the adaptability of Selenium, by demonstrating how some basic Selenium order sendkeys interpret crosswise over major scripting dialects.
Consistency offered by the WebDriver API crosswise over dialects, rearranges the way toward porting test information of one dialect to another. Test engineers wind up noticeably more prominent resources for their associations as they can be moved to any web extend, written in any programming dialect, and still have the capacity to make tests for it in a flash.
Consistency between various Selenium ties is material to most charges in the Selenium API. Yet, one must note that the cited case is a little distorted. Activity charges are surrounded in a similar configuration in each dialect. In any case, when utilizing distinctive dialects to script code, after some time, contrasts will end up noticeably obvious between the dialects. In this manner, activities that are capacity well in a specific dialect may be excess and illogical in an alternate one.
As clarified over, no unmistakable most loved rises while picking a scripting dialect for Selenium. In any case, which one ought to an association select?
What ought to be your Strategy for the Performance Testing in Cloud?
The response to this question is less direct. A few elements must be considered:
The present dialect being utilized by an undertaking for improvement: If an association has everybody utilizing Python, at that point that ought to be the perfect dialect to utilize.
Presenting another dialect isn't simple. Utilizing a dialect that QA analyzers are now alright with, is the most advantageous decision. It is additionally considerably harder to work Selenium utilizing another dialect.
Nearby support for the programming dialect ought to likewise be considered. On the off chance that nearby designers are knowledgeable about a specific dialect, at that point that dialect is a superior decision for QA groups. In the event that analyzers require help with the dialect, deformities, or advancement apparatuses, it ends up noticeably less demanding to make utilization of the effectively accessible in-house ability.
For people who haven't customized some time recently, utilizing script-accommodating dialects like Python, Ruby and so on could be the most ideal approach. They have a simple expectation to absorb information, and furthermore permit Selenium tests to be composed rapidly and with less code.
Java is the most usually utilized dialect; however its scripts can be perplexing a result of the moderately convoluted language structure.
At the point when all is said and done, each dialect has something one of a kind to offer, thus there is no outright victor. Choosing the most suitable dialect comes down to the group's specific circumstance, and what they're attempting to achieve. It is vital in such manner to look for some direction and true assistance from players who have some involvement in the field, and whose bits of knowledge can help you when settling on that essential pre-improvement choice.
Infocampus is a best institute for selenium training in Bangalore. Enrol today by contacting 9738001024 or else by visiting http://infocampus.co.in/best-selenium-testing-training-center-in-bangalore.html.
Keywords: selenium training in Bangalore
By: siyaram ray
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Article ID 1045982 (Views 309) | <urn:uuid:f3695ae0-504a-489d-ae45-7d70944e1065> | 2.65625 | 1,177 | Truncated | Software Dev. | 27.947732 | 95,549,675 |
The Zeta Function and the Prime Number Theorem
Euler was aware of the connection between the zeta function
and the sequence of prime numbers 2, 3, 5, 7,...
To see this notices that
and similarly +...
Continuing indefinitely we have
The bracketed product includes all terms of the formwhereis a prime number. This has implications for the counting functionwhich counts all the prime numbers less thanand the Prime Number Theorem:
Riemann showed that a proof of the Prime Number Theorem could be given if certain properties of the zeta function could be established. This is now called the Riemann hypothesis. These properties concern the location of the zeros of the zeta function. Equation (1) shows that the zeta function has no zeros forbut Riemann found an analytic continuation of the zeta function toand the this function did have zeros. | <urn:uuid:9d00fb98-8fb9-4f97-8579-5cff792b6a79> | 2.71875 | 187 | Academic Writing | Science & Tech. | 53.101364 | 95,549,690 |
The link between smoke blanketing of European Russia in summer 2016, Siberian wildfires and anomalies of large-scale atmospheric circulation
Analysis of smoke blanketing of European Russia (ER) in summer 2016 is presented. The results of the analysis indicate that the cause of the smoky atmosphere over ER was long-range transport of smoke from wildfires in Siberia. The aerosol optical thickness at a wavelength of 550 nm over ER in late July reached 3. The features of circulation in the troposphere over northern Eurasia in July 2016, with an anomalous east transfer of combustion products in the troposphere over thousands of kilometers, which is opposite to the westerly transfer prevailing in the mid-latitudes, are discussed. A comparison of variations in the probability distribution functions of the aerosol optical thickness is performed for ER and Siberia for the summer periods in different years with massive wildfires.
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- 1.G. I. Gorchakov, P. P. Anikin, A. A. Volokh, et al., Izv., Atmos. Ocean. Phys. 40 (3), 323–336 (2004).Google Scholar
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Mathematical biology is a branch of applied mathematics dealing with understanding and mathematically modelling the biological systems. The roots to this discipline stem from pioneering early works of Alan Turing who explained mathematically the structure of patterns such as cheetah spots, zebra stripes etc. in his seminal paper “The chemical basis of morphogenesis” using reaction diffusion systems. Ever since then, researchers have been looking into how biological systems work (from evolution, memory formation to self healing mechanisms) using a combination of several tools from non-linear dynamics, neural networks, signal processing and systems theory. We are interested in understanding the formation of both short term and long term memories using reaction diffusion principles inspired by pattern formation in animals. Our research has potential applications in engineering from search engines towards artificial biological systems.
Figure 1: The formation of spots on Cheetah can be explained using reaction-diffusion equations. [Courtesy: Wikipedia]
Figure 2: Cheetah spots generated using reaction-diffusion equations in MATLAB.
It is amazing to see how human brain gathers inputs from multiple sources and processes information parallely even in an unknown environment. This is possible because we have memory, categorized as 1) short term memory and 2) long term memory and brain does self organization in a unique way from over thousand different neuronal types and associated connections. Whenever an input is received by the human brain, certain neurons get excited and the information about the input is spread across the system of neurons. This spread of information can be thought of as a wave propagating over the space and time forming an associative spatio-temporal memory. At PNSIL, we are trying to understand and mathematically model spatio-temporal memories from first principles based on Turing’s reaction-diffusion equations and applications beyond this.
- Prof. Shayan S. Garani (Chief Investigator)
- S K Prayag Gowgi (Ph.D. student)
- Amrutha Machireddy (Ph.D. student)
- J. C. Principe, N. R. Euliano and S. Garani, “Principles and networks for self organization in space time”, Special Issue of Journal of Neural Networks, Elsevier Press, vol. 15, pp. 1069-1083, Oct. 2002.
- S. Garani and J. C. Principe, “Dynamic vector quantization of speech,” Proc.of Workshop on Self Organizing Maps., Springer-Verlag: London, pp. 238-245, July 2001.
- A. Machireddy and S. S. Garani, “Data Dependent Adaptive Prediction and Classification of Video Sequences”, in Intl. Conf. on Artificial Intelligence and Soft Computing (ICAISC), Zakopane, Poland, June 2018.
- P. Gowgi and S. S. Garani, “Density Transformation and Parameter Estimation from Back Propagation Algorithm”, in IEEE. Intl. Joint Conf. on Neural Networks (IJCNN), Vancouver, Canada, July 2016.
- P. Gowgi and S. G. Srinivasa, “Spatio-temporal map formation based on a Potential Function”, in IEEE. Intl. Joint Conf. on Neural Networks (IJCNN), Killarney, Ireland, July 2015.
- S. Garani and J. C. Principe, “A spatio-temporal vector quantizer for missing samples reconstruction,” IEEE. Proc. Intl. Joint Conf. on Neural Networks., vol. 4, pp. 2913-2917, June 2001. | <urn:uuid:dc1021ea-ae29-4833-b72e-f4ad77c55c9c> | 2.546875 | 764 | About (Org.) | Science & Tech. | 46.252692 | 95,549,712 |
Destruction of rocks and minerals by biological activities has been termed bioerosion (Neumann, 1966). It includes mechanical as well as chemical effects, that is, bioabrasion and biocorrosion (Schneider, 1976; Golubic and Schneider, 1979). However, both the processes often co-occur; they are functionally interconnected and mutually supportive. Biocorrosion can result from the activity of macro- or microorganisms and, thus, is called macrobiocorrosion and microbiocorrosion. Microbiocorrosion can also be closely associated with microbial rock formation and consolidation in stromatolitic structures (Reid et al., 2000; Macintyre et al., 2000; Garcia-Pichel et al., 2004; Dupraz and Visscher, 2005). In fact, the oldest known fossils of microboring organisms were located in lithified horizons of silicified stromatolites (Zhang and Golubic, 1987).
KeywordsBiological Activity Chemical Effect Rock Formation Microboring Organism Stromatolitic Structure
- Reid, R. P., Visscher, P. T., Decho, A. W., Stolz, J. F., Bebout, B. M., Dupraz, C. P., Macintyre, I. G., Paerl, H. W., Pinckney, J. L., Prufert-Bebout, L., Steppe, T. F., and DesMarais, D. J., 2000. The role of microbes in accretion, lamination and early lithification of modern marine stromatolites. Nature, 406, 989–992.CrossRefGoogle Scholar
- Schneider, J., 1976. Biological and inorganic factors in the destruction of limestone coasts. Contributions to Sedimentology, 6, 1–112.Google Scholar
- Zhang, Y., and Golubic, S., 1987. Endolithic microfossils (cyanophyta) from early Proterozoic stromatolites, Hebei, China. Acta Micropaleont Sinica, 4, 1–12.Google Scholar | <urn:uuid:5ce65b22-3fab-4a7e-bbf0-a58817255789> | 3.03125 | 460 | Academic Writing | Science & Tech. | 43.435356 | 95,549,716 |
Sizes and shapes of nuclei with more than 100 protons were so far experimentally inaccessible. Laser spectroscopy is an established technique in measuring fundamental properties of exotic atoms and their nuclei. For the first time, this technique was now extended to precisely measure the optical excitation of atomic levels in the atomic shell of three isotopes of the heavy element nobelium, which contain 102 protons in their nuclei and do not occur naturally. This was reported by an international team lead by scientists from GSI Helmholtzzentrum für Schwerionenforschung.
Nuclei of heavy elements can be produced at minute quantities of a few atoms per second in fusion reactions using powerful particle accelerators. The obtained results are well described by nuclear models, which suggest the nuclei to have a bubble-like structure with lower density in their center than at their surface. The results were published in a recent article in Physical Review Letters.
Inner part of the gas-filled optical cell for laser spectroscopy of nobelium isotopes.
M. Laatiaoui, GSI
Atoms consist of a positively charged nucleus surrounded by an electron shell. The inner electrons penetrate the volume of the nucleus and thus atomic level energies are influenced by the size and shape of the atomic nucleus. A difference in size of two different atomic nuclei resulting, for example, from a different number of neutrons results in a small shift of electronic energy levels.
Precise measurements of these energies are possible using laser light. Energy shifts are traced by varying the frequency and correspondingly the color of the light required to excite electrons to higher energy levels. So far, this method could only be applied to isotopes of lighter elements which are produced at larger production rates and whose atomic structure was already known from experiments with abundant long-lived or stable isotopes.
Nuclei of elements above fermium (Fm, Z=100) can be produced at minute quantities of a few atoms per second in fusion reactions and generally exist only for at most a few seconds. Therefore, their atomic structure was so far not accessible with laser spectroscopic methods.
In the current experiments, nobelium isotopes were produced by fusion of calcium ions with lead at the velocity filter SHIP at GSI’s accelerator facility. To enable laser spectroscopy, the high energetic nobelium atoms were stopped in argon gas. The results are based on a preceding experiment also conducted at GSI, exploring the atomic transitions of nobelium (No). The chemical element with atomic number 102 was discovered about 60 years ago.
The recent experiment investigated the isotopes No-254, No-253 and No-252 which differ in the number of constituent neutrons in their nuclei, with laser spectroscopy. The rates available for the experiment reached values below one ion per second for the isotope No-252.
From the measurements of the excitation frequency for the individual isotopes, the shift in color of the required laser light was determined for No-252 and No-254. For No-253, the fragmentation of the line into several hyperfine components induced by the single unpaired odd neutron was also resolved. The sizes and the shapes of the atomic nuclei were deduced from using theoretical calculations of the atomic structure of nobelium, which were carried out in collaboration with scientists from the Helmholtz Institute Jena in Germany, the University of Groningen in the Netherlands, and the University of New South Wales in Sydney, Australia.
The results confirm that the nobelium isotopes are not spherical but are deformed like an American football. The measured change in size is consistent with nuclear model calculations performed by scientists from GSI and from the Michigan State University in the USA. These calculations predict that the studied nuclei feature a lower charge density in their center than at their surface.
Thanks to these pioneering studies, further heavy nuclides will be accessible for laser spectroscopic techniques, enabling a systematic investigation of changes in size and shape in the region of heavy nuclei. These experiments are so far only possible at GSI and allow for a unique in-depth understanding of the atomic and nuclear structure of the heaviest elements. The results also play a role for the future facility FAIR (Facility for Antiproton and Ion Research), which is currently under construction at GSI. The same techniques and methods could also be employed in the low-energy branch of FAIR’s super fragment separator.
The experiments were conducted by an international team of scientists from GSI Helmholtzzentrum für Schwerionenforschung, Johannes Gutenberg-University Mainz, Helmholtz institute Mainz, TU Darmstadt, KU Leuven (Belgium), University of Liverpool (UK) und TRIUMF (Vancouver, Canada).
Dr. Ingo Peter | idw - Informationsdienst Wissenschaft
First evidence on the source of extragalactic particles
13.07.2018 | Technische Universität München
Simpler interferometer can fine tune even the quickest pulses of light
12.07.2018 | University of Rochester
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
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Countless mice, rats and rabbits die every year in the name of science – and the situation is getting worse.
The yellow nanosensor signal in the overlay image (right) shows that the cells are active. If they were unhealthy, they would appear much redder. Center: the indicator dye signal. Left: the reference dye signal. © Fraunhofer EMFT
While German laboratories used some 2.41 million animals for scientific research in 2005, by 2009 this number had grown to 2.79 million. One third were destined for fundamental biology research, and the majority were used for researching diseases and developing medical compounds and devices. People demand medicines that are safe and therapies that are tolerable, but hardly anyone is happy to accept the need for animal testing.
This is why scientists have spent years looking for methods that can replace them. Now researchers at the Fraunhofer Research Institution for Modular Solid State Technologies EMFT in Munich have found an alternative: they hope to use novel nanosensors to reduce the number of experiments that are carried out on animals. “We’re basically using a test tube to study the effects of chemicals and their potential risks. What we do is take living cells, which were isolated from human and animal tissue and grown in cell cultures, and expose them to the substance under investigation,” explains Dr. Jennifer Schmidt of the EMFT. If a given concentration of the substance is poisonous to the cell, it will die. This change in “well-being” can be rendered visible by the sensor nanoparticles developed by Dr. Schmidt and her team.
Cells – the tiniest living things – that are healthy store energy in the form of adenosine triphosphate (ATP). High levels of ATP are indicative of high levels of metabolic activity in cells. If a cell is severely damaged, it becomes less active, storing less energy and consequently producing less ATP. “Our nanosensors allow us to detect adenosine triphosphate and determine the state of health of cells. This makes it possible to assess the cell-damaging effects of medical compounds or chemicals,” says Schmidt.
In order for the nanoparticles to register the ATP, researchers give them two fluorescent dyes: a green indicator dye that is sensitive to ATP, and a red reference dye that does not change color. Next, the scientists introduce the particles to living cells and observe them under a fluorescence microscope. The degree to which the particles light up depends on the quantity of ATP present. The more yellow is visible in the overlay image, the more active are the cells. If their health were impaired, the overlay image would appear much redder. “We could in future use cancer cells to test the effectiveness of newly developed chemotherapy agents. If the nanosensors detect a low concentration of ATP in the cells, we’ll know that the new treatment is either inhibiting tumor cell growth or even killing them,” says Schmidt. “The most promising agents could then be studied further.”
The EMFT researchers’ nanoparticles are extremely well suited to the task at hand: they are not poisonous to cells, they can easily pass through cell membranes, and they can even be directed to particular points where the effect of the test substance is of most interest. But before this procedure can be applied, it must first be approved by the regulatory authorities – so the EMFT experts have a long journey ahead of them to gain approvals from various official bodies. This prospect has not, however, stopped the researchers from refining the technology and coming up with new applications for it – for instance to test the quality of packaged meat and its fitness for consumption. To this end they have developed nanosensors that can determine concentrations of oxygen and toxic amines.
Dr. rer. nat. Gerhard Mohr | Fraunhofer Research News
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
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All astrometric techniques use the properties of incoming electromagnetic radiation emitted by celestial bodies in order to determine the direction from which they where emitted or to describe the emission structure in some small portion of the sky. The problem is twofold: to collect light and measure its properties at the receiver end of an astronomical instrument and to interpret the measurements in terms of the properties of the actual emitting bodies in the sky. These two aspects of astrometry imply that one is able to describe exactly the transformation undergone by the light (or radio waves) between the celestial body down to the sensitive part of the instrument. Actually, except in one particular case of pulsar timings, one may assume that no significant effect on light is produced when crossing the interstellar and interplanetary media. So one has to consider the instrument on one side, the atmospheric effects on the other. The latter will be examined in Chap. 3. In the present chapter, we introduce the study of instrumental effects by presenting some basic results in optics that will be used throughout the book.
KeywordsPoint Spread Function Wave Train Coherence Time Spherical Aberration Chromatic Aberration
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Edited by Jamie (ScienceAid Editor), Taylor (ScienceAid Editor)
Periodicity has to do with the patterns of behaviour and properties that are seen in the periodic table.
The periodic table can be divided into various blocks based on the more advanced electron|configuration introduced at this level.
There are the s, p and d blocks. An element is in the s-block, for example, if its outermost electron is in the s sub energy level. Elements in the same block have similar properties. For example, the transition metals are all in d-block.
Period 3: Atomic Radius
Under this heading, we will look at the properties of the elements in period 3 (Na, Mg, Al, Si, P, S, Cl, Ar) in atomic radius. The atomic radius of an atom is defined as half the distance between the nuclei of two covalently bonded atoms, (called the covalent radius) as shown in the diagram below. However, it is not possible to get this measurement for noble gases since they do not bond. So instead we use the Van der Waals radius.
As you go along a period, the atomic radius decreases. This is because the increasing number of protons exerts more pull on the electrons and so moves them closer to the nucleus. Hence they take up less volume.
Period 3: Electronegativity
Electronegativity is the ability of an atom or molecule to attract electrons. Click here to see how this affects bonding.
It is measured using the Pauling scale where fluorine is given a value of 4 (the highest) and Francium 0.7 the lowest.
As you move along the period, the electronegativity increases as you can see in the below diagram. This trend is because as more protons are added and the nucleus' charge becomes higher, and the atom has more attractive power. Noble gases do not have electronegativity.
Period 3: Conductivity
Across period 3, conductivity of both electricity and heat is a story of two halves...
Na, Mg, and Al all form metallic structures where the delocalized electrons can move freely and carry electronic charge or heat energy.
Si, O, S, Cl and Ar however are insulators, this is because they bond covalently where the electrons are in a fixed position so cannot transfer electric charge or heat.
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Categories : Fundamental
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By Larry Solomon, The National Post
How do we know there’s a scientific consensus on climate change? Pundits and the press tell us so. And how do the pundits and the press know? Until recently, they typically pointed to the number 2500 – that’s the number of scientists associated with the United Nations Intergovernmental Panel on Climate Change. Those 2500, the pundits and the press believed, had endorsed the IPCC position.
To their embarrassment, most of the pundits and press discovered that they were mistaken – those 2500 scientists hadn’t endorsed the IPCC’s conclusions, they had merely reviewed some part or other of the IPCC’s mammoth studies. To add to their embarrassment, many of those reviewers from within the IPCC establishment actually disagreed with the IPCC’s conclusions, sometimes vehemently.
The upshot? The punditry looked for and recently found an alternate number to tout – “97% of the world’s climate scientists” accept the consensus, articles in the Washington Post and elsewhere have begun to claim.
This number will prove a new embarrassment to the pundits and press who use it. The number stems from a 2009 online survey of 10,257 earth scientists, conducted by two researchers at the University of Illinois. The survey results must have deeply disappointed the researchers – in the end, they chose to highlight the views of a subgroup of just 77 scientists, 75 of whom thought humans contributed to climate change. The ratio 75/77 produces the 97% figure that pundits now tout.
The two researchers started by altogether excluding from their survey the thousands of scientists most likely to think that the Sun, or planetary movements, might have something to do with climate on Earth – out were the solar scientists, space scientists, cosmologists, physicists, meteorologists and astronomers. That left the 10,257 scientists in disciplines like geology, oceanography, paleontology, and geochemistry that were somehow deemed more worthy of being included in the consensus. The two researchers also decided that scientific accomplishment should not be a factor in who could answer – those surveyed were determined by their place of employment (an academic or a governmental institution). Neither was academic qualification a factor – about 1,000 of those surveyed did not have a PhD, some didn’t even have a master’s diploma.
To encourage a high participation among these remaining disciplines, the two researchers decided on a quickie survey that would take less than two minutes to complete, and would be done online, saving the respondents the hassle of mailing a reply. Nevertheless, most didn’t consider the quickie survey worthy of response – just 3146, or 30.7%, answered the two questions on the survey:
1. When compared with pre-1800s levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?
2. Do you think human activity is a significant contributing factor in changing mean global temperatures?
The questions were actually non-questions. From my discussions with literally hundreds of skeptical scientists over the past few years, I know of none who claims that the planet hasn’t warmed since the 1700s, and almost none who think that humans haven’t contributed in some way to the recent warming – quite apart from carbon dioxide emissions, few would doubt that the creation of cities and the clearing of forests for agricultural lands have affected the climate. When pressed for a figure, global warming skeptics might say that human are responsible for 10% or 15% of the warming; some skeptics place the upper bound of man’s contribution at 35%. The skeptics only deny that humans played a dominant role in Earth’s warming.
Surprisingly, just 90% of those who responded to the first question believed that temperatures had risen – I would have expected a figure closer to 100%, since Earth was in the Little Ice Age in the centuries immediately preceding 1800. But perhaps some of the responders interpreted the question to include the past 1000 years, when Earth was in the Medieval Warm Period, generally thought to be warmer than today.
As for the second question, 82% of the earth scientists replied that that human activity had significantly contributed to the warming. Here the vagueness of the question comes into play. Since skeptics believe that human activity been a contributing factor, their answer would have turned on whether they consider a 10% or 15% or 35% increase to be a significant contributing factor. Some would, some wouldn’t.
In any case, the two researchers must have feared that an 82% figure would fall short of a convincing consensus – almost one in five wasn’t blaming humans for global warming – so they looked for subsets that would yield a higher percentage. They found it – almost – in those whose recent published peer-reviewed research fell primarily in the climate change field. But the percentage still fell short of the researchers’ ideal. So they made another cut, allowing only the research conducted by those earth scientists who identified themselves as climate scientists.
Once all these cuts were made, 75 out of 77 scientists of unknown qualifications were left endorsing the global warming orthodoxy. The two researchers were then satisfied with their findings. Are you?
Lawrence Solomon is executive director of Energy Probe and the author of The Deniers. | <urn:uuid:cdcfce49-32a5-4934-a076-32fcb47a4b0c> | 2.90625 | 1,080 | Personal Blog | Science & Tech. | 42.823196 | 95,549,827 |
Imagine looking up to the sky every night just to see the Halloween orange and chimney red glow from dozens of volcanoes on the surface of the moon. According to a new research paper just published in Nature Geosciences, humans would be able to enjoy such a show in the future.
Using recent moonquake information gathered by the seismometers installed during the Apollo missions, NASA's Marshall Space Flight Center planetary Dr Renee Weber Project, says that about 30 per cent of the lunar mantle surrounding the moon's metallic core is molten. Weber, who is in charge of the the Lunar Mapping and modelling project, claims that this liquid lava is about 1200km and 1350km deep.
So why there are no active volcanoes now? The moon's surface is dead and, in fact, we know that the latest eruptions happened billions of years ago. Perhaps this means there will be future eruptions? A group of scientists led by Mirjam van Kan Parker and Wim van Westrenen from VU University Amsterdam, may have found the answer to these questions.
Since we can't access the lava, they solved the puzzle using an ingenious technique. First they got some samples from the 350kg of rocks brought back by the Apollo missions. Then they put those rocks under the same conditions in which that molten moon lava is: more than 45,000 bars of pressure and temperatures of about 1500C.
After creating this artificial lava, they used the European Synchrotron Radiation Facility in Grenoble to analyse it using powerful X-rays. With that data, they created a computer simulation which found out that the Moon's magma is very rich in titanium. This makes it way too heavy to flow into the surface. Lava needs to be lighter than its surroundings in order for it to erupt into the surface, but this is not the case.
According to van Westrenen, "after descending, magma formed from these near-surface rocks, very rich in titanium, and accumulated at the bottom of the mantle — a bit like an upside-down volcano. Today, the Moon is still cooling down, as are the melts in its interior." That solves the why there are no volcanoes questions. But what about the future?
In the distant future, the cooler and therefore solidifying melt will change in composition, likely making it less dense than its surroundings. This lighter magma could make its way again up to the surface forming an active volcano on the Moon — what a sight that would be! | <urn:uuid:dd59fd27-26db-43e7-a358-044c350ad588> | 3.96875 | 511 | News Article | Science & Tech. | 51.448187 | 95,549,830 |
Astronomers discover what might be the largest known structure in the universe that leaves its imprint on cosmic microwave background radiation
In 2004, astronomers examining a map of the radiation leftover from the Big Bang (the cosmic microwave background, or CMB) discovered the Cold Spot, a larger-than-expected unusually cold area of the sky. The physics surrounding the Big Bang theory predicts warmer and cooler spots of various sizes in the infant universe, but a spot this large and this cold was unexpected.
The Cold Spot area resides in the constellation Eridanus in the southern galactic hemisphere. The insets show the environment of this anomalous patch of the sky as mapped by Szapudi's team using PS1 and WISE data and as observed in the cosmic microwave background temperature data taken by the Planck satellite. The angular diameter of the vast supervoid aligned with the Cold Spot, which exceeds 30 degrees, is marked by the white circles. Graphics by Gerg? Kránicz.
Credit: ESA Planck Collaboration
Now, a team of astronomers led by Dr. Istvan Szapudi of the Institute for Astronomy at the University of Hawaii at Manoa may have found an explanation for the existence of the Cold Spot, which Szapudi says may be "the largest individual structure ever identified by humanity."
If the Cold Spot originated from the Big Bang itself, it could be a rare sign of exotic physics that the standard cosmology (basically, the Big Bang theory and related physics) does not explain. If, however, it is caused by a foreground structure between us and the CMB, it would be a sign that there is an extremely rare large-scale structure in the mass distribution of the universe.
Using data from Hawaii's Pan-STARRS1 (PS1) telescope located on Haleakala, Maui, and NASA's Wide Field Survey Explorer (WISE) satellite, Szapudi's team discovered a large supervoid, a vast region 1.8 billion light-years across, in which the density of galaxies is much lower than usual in the known universe. This void was found by combining observations taken by PS1 at optical wavelengths with observations taken by WISE at infrared wavelengths to estimate the distance to and position of each galaxy in that part of the sky.
Earlier studies, also done in Hawaii, observed a much smaller area in the direction of the Cold Spot, but they could establish only that no very distant structure is in that part of the sky. Paradoxically, identifying nearby large structures is harder than finding distant ones, since we must map larger portions of the sky to see the closer structures.
The large three-dimensional sky maps created from PS1 and WISE by Dr. András Kovács (Eötvös Loránd University, Budapest, Hungary) were thus essential for this study. The supervoid is only about 3 billion light-years away from us, a relatively short distance in the cosmic scheme of things.
Imagine there is a huge void with very little matter between you (the observer) and the CMB. Now think of the void as a hill. As the light enters the void, it must climb this hill. If the universe were not undergoing accelerating expansion, then the void would not evolve significantly, and light would descend the hill and regain the energy it lost as it exits the void.
But with the accelerating expansion, the hill is measurably stretched as the light is traveling over it. By the time the light descends the hill, the hill has gotten flatter than when the light entered, so the light cannot pick up all the energy it lost upon entering the void. The light exits the void with less energy, and therefore at a longer wavelength, which corresponds to a colder temperature.
Getting through a supervoid can take millions of years, even at the speed of light, so this measurable effect, known as the Integrated Sachs-Wolfe (ISW) effect, might provide the first explanation one of the most significant anomalies found to date in the CMB, first by a NASA satellite called the Wilkinson Microwave Anisotropy Probe (WMAP), and more recently, by Planck, a satellite launched by the European Space Agency.
While the existence of the supervoid and its expected effect on the CMB do not fully explain the Cold Spot, it is very unlikely that the supervoid and the Cold Spot at the same location are a coincidence. The team will continue its work using improved data from PS1 and from the Dark Energy Survey being conducted with a telescope in Chile to study the Cold Spot and supervoid, as well as another large void located near the constellation Draco.
The study is being published online on April 20 in Monthly Notices of the Royal Astronomical Society by the Oxford University Press. In addition to Szapudi and Kovács, researchers who contributed to this study include UH Manoa alumnus Benjamin Granett (now at the National Institute for Astrophysics, Italy), Zsolt Frei (Eötvös Loránd), and Joseph Silk (Johns Hopkins).
Founded in 1967, the Institute for Astronomy at the University of Hawaii at Manoa conducts research into galaxies, cosmology, stars, planets, and the sun. Its faculty and staff are also involved in astronomy education, deep space missions, and in the development and management of the observatories on Haleakala and Maunakea. The Institute operates facilities on the islands of Oahu, Maui, and Hawaii.
The Pan-STARRS1 Surveys (PS1) have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, and the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation Grant No. AST-1238877, the University of Maryland, Eötvös Loránd University (ELTE), and the Los Alamos National Laboratory.
Dr. István Szapudi,
+1 808 956-6196,
Dr. András Kovács,
+34 93 176 3966,
Louise Good | EurekAlert!
Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences
Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication
16.07.2018 | Chinese Academy of Sciences Headquarters
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences | <urn:uuid:e7c21b89-5ae0-4caa-a28b-b27f0d41dd76> | 3.84375 | 2,029 | Content Listing | Science & Tech. | 38.489084 | 95,549,852 |
Two recent publications highlight the rapidly-changing nature of our current thinking in relation to human evolution.
|Image via Pixabay|
The first article, published in the journal Nature and summarised here, puts back the arrival of hominins in east Asia several hundred thousand years, from 1.8 million to 2.1 million years ago. Hominins are the evolutionary line that led to us, Homo sapiens, as well as earlier Homo species and members of the genus Australopithecus. The article clearly illustrates to students how, as new evidence becomes available, our scientific knowledge can be updated accordingly.
The second article, published here in the open access journal Trends in Ecology & Evolution, claims that recent evidence no longer supports the notion that H. sapiens evolved in a localised area in east Africa, and instead shows a more complex, geographically-dispersed evolutionary history throughout Africa. The authors conclude that this changing view, of a more 'mosaic-like' evolution of recent human ancestors in a multi-regional pattern across Africa, means that earlier hypotheses and assumptions need to be adjusted to take these new facts into account. The article also highlights knowledge gaps and areas in which future research should focus. This can be used to reinforce with students the point that good science often asks as many new questions as it answers existing ones.
By using examples like this from the field of paleoanthropology, students get to see both the latest research and the ever-changing nature of science. | <urn:uuid:40704040-0a8c-409c-a0b8-1795ceb59184> | 3.703125 | 307 | Personal Blog | Science & Tech. | 29.895793 | 95,549,870 |
The transverse orientation of stomata
by Butterfass T. (1987)
Botanisches Institut der Johann Wolfgang Goethe-UniversitätFrankfurt a. M. 11Federal Republic of Germany
in Bot. Rev (1987) 53: 415-441 – https://doi.org/10.1007/BF02858323 –
The orientation of cell walls co-determines development. The orientation of the slits of the stomata can be used for analyzing the factors involved.
A comprehensive and annotated list is given of those plant species most of whose stomata are known to be oriented transversely to the long axis of an organ or a main rib. Included are also species showing only a trend toward transverse orientation.
Transverse orientation is known from a few mosses, from Bennettitatae, fromAzolla and some other ferns, and from species of about 45 families of spermatophytes. It could be confirmed that succulent species show the trait more often than do other plants.
Two thirds of the species listed belong to the Caryophyllales and Santalales, a few only to Asteraceae, but none to Rubiaceae, Cyperaceae, Poaceae, or Orchidaceae. Hence, the incidence of succulent species or of species with some succulent traits within the two orders and the lack of such species among other taxa may account in part for the distribution.
On the other hand, many succulent species do not show transverse orientation whereas in, e.g., Casuarina and Tamaricaceae transverse orientation goes together with non-succulent xeromorphy; Azolla shows no xeromorphy at all. Various factors, separately or together, may be involved. Proposed mechanisms determining the orientation of cell walls have been compiled from literature and are discussed. | <urn:uuid:f0399545-816f-4f9d-b56f-bba695914449> | 3.234375 | 393 | Academic Writing | Science & Tech. | 39.048202 | 95,549,888 |
Advanced Accelerator R&D
Scientists at SLAC have found a new method to create coherent beams of twisted light – light that spirals around a central axis as it travels. It has the potential to generate twisted light in shorter pulses, higher intensities and a much wider range of wavelengths, including X-rays, than is currently possible.
Dao Xiang, a SLAC accelerator physicist, has received an international award for his work on a technique for tuning an electron beam with a laser to produce X-ray pulses with more uniform and predictable properties.
A tool developed half a century ago for sorting subatomic particles has been redesigned to measure X-ray laser pulses at SLAC's Linac Coherent Light Source (LCLS). | <urn:uuid:7395069d-4a92-40ac-be1a-c83ceb435df1> | 2.921875 | 150 | News (Org.) | Science & Tech. | 31.155 | 95,549,915 |
Branched Polymers and Gels
Polymers are giant molecules that are made of millions of atoms. They are the repetition of an elementary unit called monomer. They are used as plastics, paints, adhesives, rubbers, and in some future, as batteries. They have changed completely our everyday life by superseding natural materials such as wood, iron, etc. Our understanding of the structure of synthetic polymers has increased tremendously these last 20 years. They may be either linear or branched. In the former case, one makes react divalent monomers, that may interact only by two functional units, leading to a linear structure. In the latter case, multifunctional units react, leading to a structure that is randomly branched. A very interesting aspect of this type of reaction is that as time proceeds, one eventually goes from a viscous fluid called a sol to an elastic solid called a gel. The sol-gel transition was considered first in the forties in its mean field version by Flory and by Stockmayer and Zimm. It was improved recently by noting that it is directly related to the percolation transition in Physics (de Gennes, 1976; Stauffer, 1976). More recently, the fractal aspects of these branched polymers and gels were considered both theoretically and experimentally. Although the ideas developed for these synthetic polymers are probably too simplistic for direct use in biological problems, we believe that some of them might survive even when complications such as rigidity, presence of electrical charges, and eventually others are taken into account. In what follows, we will discuss the simplest possible case of sol-gel transition.
KeywordsFractal Dimension Scattered Intensity Single Polymer Percolation Transition Fractal Aspect
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- Bouchaud E., Delsanti M., Adam M., Daoud M. and Durand D., J. Phys. Lett. 47 (1986) 1273.Google Scholar
- Flory P.J., Principles of Polymer Chemistry (Cornell University Press, Ithaca, 1953).Google Scholar
- Gennes, P.G. de, Scaling Concepts in Polymer Physics (Cornell Univ. Press, Ithaca, 1979).Google Scholar
- Mandelbrot B.B., The Fractal Geometry of Nature (Freeman, San Francisco, 1977).Google Scholar | <urn:uuid:878a9dc6-c3b9-46be-8645-8e386fd64657> | 2.703125 | 501 | Academic Writing | Science & Tech. | 43.966717 | 95,549,926 |
David Williams–To date, humanity has been able to discover and eventually tap on a number of renewable energy sources. From wind mills to solar panels, there have been all sorts of inventions and gadgets that come with the ability to generate electricity from certain natural sources. Now a team of engineers from the Massachusetts Institute of Technology (MIT) developed a new device that appears to generate electricity out of nothing but air.
This device, which has been described as miraculous in some online reports, is referred to by the engineers who invented it as a thermal resonator. It is said to function by relying on fluctuations in temperature in the environment. This means that changes in temperature between night and day is what allows it to produce electricity seemingly on its own.
The inventors said their device can be used without the need for any batteries, sunlight, wind, or other energy sources. This makes it ideal for use in situations where tapping the above sources simply isn’t possible. Its ability to generate electricity in this regard means it could be suitable as a source of power for certain types of sensors and communications devices that can run for years without the need for batteries.
According to Michael Strano, the lead engineer who worked on the project, they came up with the concept and completed its execution all on their own. “We basically invented this concept out of whole cloth. We’ve built the first thermal resonator,” he explained. “It’s something that can sit on a desk and generate energy out of what seems like nothing.”
As for how exactly they came upon their ideas, Strano said that they noticed that they simply applied the known science on what is apparently an obvious free and natural power source. “We are surrounded by temperature fluctuations of all different frequencies all of the time,” he said. “These are an untapped source of energy.”
The thermal resonator was made out of materials that are conducive to its main method of energy production. That is, it uses materials that can capture heat from the surrounding air and also release it afterwards. The researchers opted to use metal foam, which is made out of copper or nickel material, and later coated with a layer of graphene.
The metal foam was then infused with a special kind of wax called octadecane. It is said that this material has the ability to change between solid and liquid phases based on the temperature. So far, the engineers have been able to create a proof of concept version of the material that has shown great promise.
The initial effort by the team resulted in a material that can produce 350 millivolts of potential energy, as well as 1.3 milliwatts of power following a 10-degree Celsius change in temperature between day and night. This kind of energy output is said to be just perfect for small environmental sensors and certain communications systems, said the engineers.
Since the power output is far too low for everyday devices, the final working version of the thermal resonator created by the engineers would probably be more suited to special use cases such as in space rovers that are deployed in remote locations like moons and other planets. For those kinds of applications, it could be designed to function as a long-lasting low-power energy source that is made out of local materials instead of being built with pre-made components.
The thermal resonator does seem to have a lot of potential for space exploration and other exploratory endeavors. However, the engineers will need to create functional prototype versions that work in space first before that statement can be said with full certainty.
Read more about alternative energy inventions at Inventions.news. | <urn:uuid:f6b01536-6b32-4ae1-b125-45832a6ec3b5> | 3.8125 | 743 | News Article | Science & Tech. | 39.430704 | 95,549,932 |
Each of your body's trillions of cells depends upon thousands of chemical reactions. The chemical reactions that take place inside your body could take place in a test tube, but they'd happen much more slowly -- too slowly to support the activities of a living organism. Enzymes are proteins within living organisms that help chemical reactions along. Their ability to function and the speed with which they work is influenced by several factors. Some of those factors are other chemicals.
How Enzymes Work
Chemical reactions involve the breaking and formation of bonds between atoms. Breaking the bonds of the initial chemicals -- the reactants -- takes energy. That's called the activation energy. Enzymes are proteins that grab on to the reactants and orient them in such a way that the activation energy is lower. The reactants are also called substrates. Enzymes bind substrates in specific locations called active sites. Active sites are shaped in a way that allows them to latch on to specific substrates. The bound enzyme-substrate complex makes it easier for reactants to break their bonds and form new ones in the product. Then the product is released from the enzyme.
The shape of the active site is what allows enzymes to work. If the active site is distorted, the substrate will not bind and the reaction will not be helped along. Some enzymes require cofactors to assume the proper shape. Cofactors can be in the form of inorganic atoms or organic molecules. For example, an ionized zinc atom -- one that has lost a couple of electrons -- is necessary in the enzyme alcohol dehydrogenase, used to metabolize alcohol. The molecule nicotinamide adenine dinucleotide is a common organic molecular cofactor, also called a coenzyme. It often participates in reactions that require the transfer of hydrogen atoms or ions. Coenzymes and inorganic cofactors may be necessary for an enzyme to work, and if there aren't enough of them, then the overall reaction rate will be slow.
Each enzyme has one specific function. An enzyme that splits a fructose molecule into two parts cannot be used to release oxygen from red blood cells. For a reaction to happen, both the enzyme and the substrate need to be present. The reaction rate can be limited by a shortage of either enzyme or substrate. Put another way, if there is a lot of substrate in a cell and not much enzyme, adding more enzyme will increase the reaction rate. Conversely, if there's a lot of enzyme and not much substrate, adding substrate will increase the reaction rate.
Faster Reaction Rates
The actual speed of an enzyme-catalyzed reaction doesn't change. That is, the time from binding of the substrate to release of the product is the same for each particular type of enzyme. When one talks about speeding up the action of an enzyme, one means increasing the number of enzymes actively participating in chemical reactions so that the total number of reactions goes up. For example, If there's not enough zinc to match with all of a specific type of DNA-processing enzyme in a cell, then adding more zinc will increase the reaction rate by making it possible for more enzymes to be active. The same with adding more substrate or more enzyme: The action gets sped up by allowing more enzymes to catalyze chemical reactions, not by speeding up any one particular enzyme. | <urn:uuid:65662565-7b29-4cee-ac6a-703ae4b6bd88> | 4.34375 | 678 | Knowledge Article | Science & Tech. | 40.867866 | 95,549,934 |
WASHINGTON — NASA’s Voyager 1 spacecraft has reached the outer edge of the solar system where wind from the Sun is no longer blowing outward, but sideways, the US space agency said.
The spacecraft was launched in 1977 and has since snapped images of Earth and other planets in the solar system and provided NASA with crucial information as it makes its long journey into outer space.
NASA researchers think Voyager 1 will leave the solar system and enter interstellar space, or the area in between the end of the Sun’s influence and the next star system, in about four years.
For now, Voyager 1 is 17.4 billion kilometers (10.8 billion miles) from the Sun in “an area where the velocity of the hot ionized gas, or plasma, emanating directly outward from the sun has slowed to zero,” the space agency said.
“Scientists suspect the solar wind has been turned sideways by the pressure from the interstellar wind in the region between stars.”
NASA noticed that the solar wind’s outward speed had slowed to zero back in June, but wanted to look at readings from Voyager 1 over the next four months to be sure.
The data was presented late Monday at the American Geophysical Union meeting in San Francisco, California.
“When I realized that we were getting solid zeroes, I was amazed,” said Rob Decker, a Voyager Low-Energy Charged Particle Instrument co-investigator and senior scientist at Johns Hopkins University.
“Here was Voyager, a spacecraft that has been a workhorse for 33 years, showing us something completely new again.”
NASA described the finding as “a major milestone in Voyager 1’s passage through the heliosheath, the turbulent outer shell of the sun’s sphere of influence, and the spacecraft’s upcoming departure from our solar system.” | <urn:uuid:5a67f5f1-1333-4038-a3af-bb88bc7a7d82> | 3.90625 | 388 | News Article | Science & Tech. | 45.426595 | 95,549,941 |
20 July 2018
The slow rise of the Sun’s magnetism
Published online 17 July 2016
Fiery, loop-shaped magnetic fields rise from the Sun’s interior at a slower speed than previously predicted.
Magnetic fields formed deep in the Sun’s interior rise to the surface and manifest as solar active regions at speeds slower than previously predicted, according to a new study1.
Astrophysicist Aaron Birch from Germany’s Max Planck Institute for Solar System Research and colleagues in Germany, the United States and the United Arab Emirates, developed a new approach to analyse the Sun’s tubular magnetic fields, called magnetic flux tubes, and found they rose at a speed no greater than 150 meters per second (m s−1) at a depth of 20,000 km, well below previous predictions of 500 m s−1.
When the sun’s plasma — one of the four fundamental states of matter — is set in motion in the solar interior, a magnetic field concentration may form, rising to the surface and creating a pair of sunspots. The details of this process are still poorly understood.
The sun’s magnetic fields are involved in all aspects of solar activity, including in solar flares, which are brief eruptions of high-energy radiation from the Sun’s surface, and coronal mass ejections, powerful eruptions of plasma from the Sun into space.
The team’s unique approach involved comparing results of observations from NASA’s Helioseismic and Magnetic Imager with previously unfeasible numerical simulations of the upper layers of the Sun.
“The rapid growth in computer power in the past few years has made it possible to carry out simulations of the size needed to address the rise of magnetic flux concentrations below the solar surface and to make direct comparisons with observations,” says astrophysicist and study co-author Laurent Gizon from New York University Abu Dhabi’s Center for Space Science.
- Birch, A. C. et al. A low upper limit on the subsurface rise speed of solar active regions. Science Advances 2, e1600557 (2016). | <urn:uuid:9ed543a0-6738-4085-9c1f-e0e062f0062e> | 3.640625 | 447 | Truncated | Science & Tech. | 41.69414 | 95,550,020 |
Structural components in aircraft engines are subjected to multiaxial loads when in service. For such components, life prediction methodologies are dependent on the accuracy of the constitutive models that determine the elastic and inelastic portions of a loading cycle. A threshold surface (such as a yield surface) is customarily used to differentiate between reversible and irreversible flow. For elastoplastic materials, a yield surface can be used to delimit the elastic region in a given stress space. The concept of a yield surface is central to the mathematical formulation of a classical plasticity theory, but at elevated temperatures, material response can be highly time dependent. Thus, viscoplastic theories have been developed to account for this time dependency. Since the key to many of these theories is experimental validation, the objective of this work (refs. 1 and 2) at the NASA Lewis Research Center was to verify that current laboratory techniques and equipment are sufficient to determine flow surfaces at elevated temperatures. By probing many times in the axial-torsional stress space, we could define the yield and flow surfaces. A small offset definition of yield (10 me) was used to delineate the boundary between reversible and irreversible behavior so that the material state remained essentially unchanged and multiple probes could be done on the same specimen. The strain was measured with an off-the-shelf multiaxial extensometer that could measure the axial and torsional strains over a wide range of temperatures. The accuracy and resolution of this extensometer was verified by comparing its data with strain gauge data at room temperature. The extensometer was found to have sufficient resolution for these experiments. In addition, the amount of crosstalk (i.e., the accumulation of apparent strain in one direction when strain in the other direction is applied) was found to be negligible. Tubular specimens were induction heated to determine the flow surfaces at elevated temperatures. The heating system induced a large amount of noise in the data. By reducing thermal fluctuations and using appropriate data averaging schemes, we could render the noise inconsequential. Thus, accurate and reproducible flow surfaces (see the figure) could be obtained. | <urn:uuid:9f146441-d1ad-4f20-bd0c-d05d9b523a25> | 2.765625 | 437 | Academic Writing | Science & Tech. | 19.72025 | 95,550,033 |
Even though the radial velocity technique has detected almost all of the 269 extrasolar planets discovered to date, this method does not directly observe the light from the planet. The ability to directly detect this light would allow spectra of extrasolar planets to be obtained, providing information about their information and evolution through the investigation of their composition and structure. To date, none of the extrasolar planets found using the radial velocity technique have been directly imaged, as these faint companions are too close to their bright parent stars. White dwarfs are intrinsically faint objects and can be upto 10,000 times less luminous than their main sequence progenitors, substantially increasing the probability of directly imaging an extrasolar planet in orbit around them.\ud The Degenerate Objects around Degenerate Objects (DODO) survey aims to obtain a direct image of an extrasolar planet in a wide orbit around a white dwarf. By acquiring J band images of 26 equatorial and northern hemisphere white dwarfs a year or two apart, common proper motion companions to the white dwarfs can be identified. The discovery of such a system could supply new information on the frequency and mass distribution of extrasolar planets around intermediate mass main sequence starts and confirm whether these companions can survive the final stages of stellar evolution. In addition, the direct detection of an extrasolar planet in orbit around a white dwarf would allow the spectroscopic investigation of planets much older than any previously found.\ud Using the 24 white dwarfs in the DODO survey within 20pc, the frequency of substellar companions with effective temperatures > 500K and projected physical separations from the white dwarf between 60-200AU is estimated to be <5%. For the same range of projected physical separations, the frequency of substellar companions with masses >10Mjup is estimated to be<9%
To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request. | <urn:uuid:1952e932-a574-4ed0-b7d7-32ddb885f4e0> | 3.578125 | 392 | Academic Writing | Science & Tech. | 15.465625 | 95,550,035 |
It was once thought that each cell in a person's body possesses the same DNA code and that the particular way the genome is read imparts cell function and defines the individual.
For many cell types in our bodies, however, that is an oversimplification. Studies of neuronal genomes published in the past decade have turned up extra or missing chromosomes, or pieces of DNA that can copy and paste themselves throughout the genomes.
The only way to know for sure that neurons from the same person harbor unique DNA is by profiling the genomes of single cells instead of bulk cell populations, the latter of which produce an average. Now, using single-cell sequencing, Salk Institute researchers and their collaborators have shown that the genomic structures of individual neurons differ from each other even more than expected. The findings were published November 1 in Science.
"Contrary to what we once thought, the genetic makeup of neurons in the brain aren't identical, but are made up of a patchwork of DNA," says corresponding author Fred Gage, Salk's Vi and John Adler Chair for Research on Age-Related Neurodegenerative Disease.
In the study, led by Mike McConnell, a former junior fellow in the Crick-Jacobs Center for Theoretical and Computational Biology at the Salk, researchers isolated about 100 neurons from three people posthumously. The scientists took a high-level view of the entire genome---- looking for large deletions and duplications of DNA called copy number variations or CNVs---- and found that as many as 41 percent of neurons had at least one unique, massive CNV that arose spontaneously, meaning it wasn't passed down from a parent. The CNVs are spread throughout the genome, the team found.
The miniscule amount of DNA in a single cell has to be chemically amplified many times before it can be sequenced. This process is technically challenging, so the team spent a year ruling out potential sources of error in the process.
"A good bit of our study was doing control experiments to show that this is not an artifact," says Gage. "We had to do that because this was such a surprise---- finding out that individual neurons in your brain have different DNA content."
The group found a similar amount of variability in CNVs within individual neurons derived from the skin cells of three healthy people. Scientists routinely use such induced pluripotent stem cells (iPSCs) to study living neurons in a culture dish. Because iPSCs are derived from single skin cells, one might expect their genomes to be the same.
"The surprising thing is that they're not," says Gage. "There are quite a few unique deletions and amplifications in the genomes of neurons derived from one iPSC line."
Interestingly, the skin cells themselves are genetically different, though not nearly as much as the neurons. This finding, along with the fact that the neurons had unique CNVs, suggests that the genetic changes occur later in development and are not inherited from parents or passed to offspring.
It makes sense that neurons have more diverse genomes than skin cells do, says McConnell, who is now an assistant professor of biochemistry and molecular genetics at the University of Virginia School of Medicine in Charlottesville. "The thing about neurons is that, unlike skin cells, they don't turn over, and they interact with each other," he says. "They form these big complex circuits, where one cell that has CNVs that make it different can potentially have network-wide influence in a brain."
Spontaneously occurring CNVs have also been linked to risk for brain disorders such as schizophrenia and autism, but those studies usually pool many blood cells. As a result, the CNVs uncovered in those studies affect many if not all cells, which suggests that they arise early in development.
The purpose of CNVs in the healthy brain is still unclear, but researchers have some ideas. The modifications might help people adapt to new surroundings encountered over a lifetime, or they might help us survive a massive viral infection. The scientists are working out ways to alter genomic variability in iPSC-derived neurons and challenge them in specific ways in the culture dish.
Cells with different genomes probably produce unique RNA and then proteins. However, for now, only one sequencing technology can be applied to a single cell.
"If and when more than one method can be applied to a cell, we will be able to see whether cells with different genomes have different transcriptomes (the collection of all the RNA in a cell) in predictable ways," says McConnell.
In addition, it will be necessary to sequence many more cells, and in particular, more cell types, notes corresponding author Ira Hall, an associate professor of biochemistry and molecular genetics at the University of Virginia. "There's a lot more work to do to really understand to what level we think the things we've found are neuron-specific or associated with different parameters like age or genotype," he says.
Other authors on the study are Michael Lindberg and Svetlana Shumilina of the Department of Biochemistry and Molecular Genetics at the University of Virginia School of Medicine; Kristen Brennand, now at the Icahn School of Medicine at Mount Sinai in New York; Julia Piper, now at Harvard University in Cambridge, Massachusetts; Thierry Voet and Joris Vermeesch of the Center for Human Genetics, KU Leuven, Leuven, Belgium; Chris Cowing-Zitron of Salk's Laboratory of Genetics; and Roger Lasken of the J. Craig Venter Institute in San Diego.
This work was supported by the Crick-Jacobs Center for Theoretical and Computational Biology, the G. Harold & Leila Y. Mathers Foundation, the National Institutes of Health, the Leona M. and Harry B. Helmsley Charitable Trust, the JPB Foundation, and the Burroughs Wellcome Fund.About the Salk Institute for Biological Studies:
Faculty achievements have been recognized with numerous honors, including Nobel Prizes and memberships in the National Academy of Sciences. Founded in 1960 by polio vaccine pioneer Jonas Salk, M.D., the Institute is an independent nonprofit organization and architectural landmark
Kat Kearney | EurekAlert!
Study relating to materials testing Detecting damages in non-magnetic steel through magnetism
23.07.2018 | Technische Universität Kaiserslautern
Innovative genetic tests for children with developmental disorders and epilepsy
11.07.2018 | Christian-Albrechts-Universität zu Kiel
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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They are diurnal, hunting during the day, and are known to move, looping end over end, or contract, in response to light. New research published in BioMed Central's open access journal BMC Biology shows that stinging cells (cnidocytes) in hydra tentacles, which the animals use for self protection and to catch prey, are linked via a simple nervous system to primitive light responsive cells that co-ordinate the animals' feeding behavior.
This is the fresh water polyp, Hydra magnipapillata. Credit: Dr. David Plachetzki, University of California
Hydra are members of a family of radially symmetric animals (Cnidaria), all of which use specialized cnidocytes to catch prey. This family also includes well-known creatures such as jellyfish and corals, which, like other cnidarians, have the simple design of a mouth surrounded by tentacles. Hydra tentacles contain barbed, poison containing cnidocytes that they use to stun animals like the water flea, Daphnia, before eating them alive, and to protect themselves from attack by other animals.
Researchers from the University of California lead by Dr David Plachetzki have discovered that the light sensitive protein opsin found in sensory cells is able to regulate the firing of harpoon-like cnidocytes. These light sensitive neurons are found integrated into arsenals that include the stinging cnidocytes as well as desmoneme cnidocytes, used to grasp prey, and sticky isorhiza, which help the hydra to summersault at 10cm a day.
The linking of opsin to cnidocytes explains how hydra are able to respond to light even though they do not have eyes. Dr Plachetzki described how other proteins necessary for phototransduction are also present in the sensory cells. "Not only did we find opsin in the sensory neurons that connect to cnidocytes in the hydra, but we also found other components of phototransduction in these cells. These included cyclic nucleotide gated ion channels (CNG) required to transfer the signal and a hydra version of arrestin, which wipes the phototransduction slate clean for a second signal."
Dr Plachetzki continued, "We were also able to demonstrate that cnidocyte firing itself is effected by the light environment and that these effects are reversed when components of the phototransduction cascade are turned off."
Cnidarians have been around for over 600 million years. However the hydra's simple approach to using light, to aid survival and increase their chances of catching prey, uses the same visual pathway as humans and hints at a common ancestor.
Notes to Editors1. Cnidocyte discharge is regulated by light and opsin-mediated phototransduction
Article citation and URL available on request on the day of publication.
2. BMC Biology is the flagship biology journal of the BMC series, publishing open-access, peer-reviewed research and methodology articles of special importance and broad interest in any area of biology, as well as reviews, opinion pieces, comment and Q&As on topics of special or topical interest.
3. BioMed Central (http://www.biomedcentral.com/) is an STM (Science, Technology and Medicine) publisher which has pioneered the open access publishing model. All peer-reviewed research articles published by BioMed Central are made immediately and freely accessible online, and are licensed to allow redistribution and reuse. BioMed Central is part of Springer Science+Business Media, a leading global publisher in the STM sector.
Dr. Hilary Glover | EurekAlert!
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
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The secret sulfate code that lets the bad Tau in
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For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
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Metal nanoshells are a new class of nanoparticles with highly tunable optical properties. Metal nanoshells consist of a dielectric core nanoparticle such as silica surrounded by an ultrathin metal shell, often composed of gold for biomedical applications. Depending on the size and composition of each layer of the nanoshell, particles can be designed to either absorb or scatter light over much of the visible and infrared regions of the electromagnetic spectrum, including the near infrared region where penetration of light through tissue is maximal. These particles are also effective substrates for surface-enhanced Raman scattering (SERS) and are easily conjugated to antibodies and other biomolecules. One can envision a myriad of potential applications of such tunable particles. Several potential biomedical applications are under development, including immunoassays, modulated drug delivery, photothermal cancer therapy, and imaging contrast agents.
Mendeley saves you time finding and organizing research
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In this chapter, we will consider motion in central potentials. We first reduce the time independent Schrödinger equation to a one-dimensional (radial) problem. We then determine the bound states for the most important case of an attractive Coulomb potential. Finally, we transform the two-body problem into a one-body problem with a potential, so that our treatment of motion in a Coulomb potential also covers the nonrelativistic hydrogen atom.
KeywordsWave Packet Recursion Relation Coulomb Potential Orbital Angular Momentum Energy Eigenvalue
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Planetary scientists located eight of these geological features, called scarps, on the Red Planet. An analysis of the scarps revealed that thick ice hides just below the surface. This ice, the researchers say, could be a tempting target for future exploration - as well as a valuable resource for Earthlings camped out on Mars.
"We've found a new window into the ice for study, which we hope will be of interest to those interested in all aspects of ice on Mars and its history," said Colin Dundas, a member of the U.S. Geological Survey's Astrogeology Science Center in Arizona and an author of a report published Thursday in the journal Science.
The newer Mars Reconnaissance Orbiter mapped the surface in greater detail. Dundas and his colleagues used its pictures to locate exposed ice in small craters, glaciers and ice sheets. "The high-resolution data has greatly improved our understanding of various ice-related land forms," he said.
These cliffs are "rare peeks into the subsurface of Mars, giving us access to an undisturbed slice through Mars' ice in the mid-latitudes - a fantastic find!" said Susan Conway, a planetary scientist at the University of Nantes in France who was not involved with this research.
Open University's Matt Balme, a planetary scientist in Britain who did not participate in this study, said the key findings were the color images of a bluish tint. That indicates a sub-layer that is "somehow compositionally different" than the red dirt. It is unlikely that the frozen sheets are a mix of water and soil. "If the conclusions of the paper are correct," he said, "you're looking at something that's almost pure ice."
The scarps exist along the planet's middle latitudes, ruling out glaciers that migrated from the poles. The study authors propose that these ice sheets formed when thick snows blanketed Mars. Balme agreed that snowfall probably created the ice over a period of a few thousand years.
These slopes are unusually steep, Balme said, though he imagines that the scarps look similar to glacial moraines on Earth.
The sheets' proximity to the surface makes them accessible, in theory, to robot explorers. "This subsurface ice could contain valuable records of the Martian climate, just like the Greenland and Antarctic ice cores," Conway said. In August, geochemists obtained 2.7-million-year-old ice samples from Antarctica - the oldest ever - and they plan to study air bubbles trapped within them to learn about Earth's prehistoric atmosphere.
And flesh-and-blood explorers might benefit, too (though the middle latitudes of Mars appear to be colder, less welcoming terrain than regions closer to the equator). "If we were to send humans to live on Mars for a substantial period of time, it would be a fantastic source of water," Balme said. Astronauts living in the pits would have a vital raw material next door. All a thirsty astronaut would have to do would be to go at the scarp with a hammer and, presto, fresh Martian ice chips.
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Local weather change is altering the place species dwell all around the planet. With international warming, species are transferring in the direction of the poles and up elevation the place temperature is decrease. Nonetheless, together with international local weather change, the world can also be experiencing large modifications in land-use which can additionally influence the place species dwell. Might each of those forces be influencing present modifications in species distributions?
Fengyi Guo, an MPhil scholar within the Faculty of Organic Sciences on the College of Hong Kong (HKU), determined to discover this query together with her adviser Dr Timothy Bonebrake (HKU) and Dr Jonathan Lenoir, a Junior Analysis Scientist on the Nationwide Heart for Scientific Analysis (CNRS) in France. Their findings, lately revealed in Nature Communications, spotlight the significance of land-use change, which interacts with local weather change to drive species distribution shifts alongside elevation. By re-analyzing information on 2,798 elevational vary shifts of vegetation and animals throughout 43 websites globally they discovered that species shifts are typically constrained by surrounding forest cowl. In cooler areas of the world, species shift at decrease charges with rising forest loss. Conversely, in hotter areas just like the tropics, the shift fee is accelerated with intensive deforestation.
The outcomes of this analysis have a number of implications for understanding international change impacts on biodiversity. An emphasis on local weather change for understanding how species change their distributions has been essential lately however should be understood within the context of land-use change as properly. Moreover, the outcomes present that tropical species could also be particularly susceptible to the twin results of local weather and land-use modifications. Lastly, how species reply to each habitat loss and altering climates ought to be thought-about rigorously for efficient conservation and administration of biodiversity.
Growing documentation of proof for species redistribution underneath local weather change lately made this analysis doable. “Whereas the significance of land-use change for climate-driven species shifts has lengthy been acknowledged, how land-use change is essential or to what extent it impacts species redistribution was by no means absolutely appreciated” famous Miss Guo. “A lot of the research we reviewed on this work acknowledged that land-use remained unchanged over time whereas the information urged in any other case and our outcomes confirmed that these modifications could have essential implications.”
Dr Bonebrake added additional that “this work additionally sheds mild on doable local weather change impacts on the species of Hong Kong — whereas warming could also be inflicting species to shift their distributions right here, each forest restoration in nation parks and forest loss from growth in current a long time could hinder our capacity to detect modifications as species distributions shifts shall be a consequence of a number of interacting human impacts.”
General the analysis emphasizes how species should cope with a number of human impacts on the pure world. Whereas some species could possibly transfer (and do transfer) in response to local weather change and/or land-use change, others could not. These species which can be unable to reply successfully to warming or habitat loss face a excessive threat of extinction.
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The chemical compounds can be a defense or can be an aromatic call for help to attract enemies of the attacking insect. Researchers from Virginia Tech, Michigan State University, and Georg-August-University Göttingen have discovered how plants produce the defensive compounds.
The research is reported this week in the online early edition of the Proceedings of the National Academy of Sciences. The article, "Herbivore-induced and floral homoterpene volatiles are biosynthesized by a single P450 enzyme (CYP82G1) in Arabidopsis," is by Sungbeom Lee, postdoctoral associate in biological sciences; Somayesadat Badieyan, Ph.D. student in biological systems engineering; and David R. Bevan, associate professor of biochemistry, all at Virginia Tech; Marco Herde, postdoctoral associate with the Michigan State University, Department of Biochemistry and Molecular Biology; Christiane Gatz, professor and head of the Albrecht-von-Haller-Institute for Plant Sciences at Georg-August-University Göttingen, Germany, and Dorothea Tholl, assistant professor of biological sciences at Virginia Tech.
To gain detailed insight into volatile defense metabolism and its regulation in plant tissues, the researchers focused on the formation of two common volatile compounds, or homoterpenes -- DMNT (4,8-dimethylnona-1,3,7-triene) and TMTT (4,8,12-trimethyltrideca-1,3,7,11-tetraene). They discovered that formation of both compounds is initiated by the same P450 enzyme – belonging to a family of enzymes that initiates oxidation of organic compounds in most plants, animals, and bacteria. In plants, the enzyme is specifically activated by insect attack.
" We are excited to finally have elucidated the biosynthesis of these common plant volatiles. The discovered P450 protein was a long-missing enzymatic link in the formation of homoterpenes," said Tholl.
Lee and colleagues created a model using mammalian forms of P450 to study the catalytic specificity of the plant enzyme in greater detail. "The approach supports future efforts to fully understand and optimize the enzymatic reaction," said Tholl. "A primary aim of the study is to engineer the discovered enzymatic pathway in important crop plants to improve their natural pest controls."
"This work illustrates the power of combining computational model-building with experimental methods in elucidating important biochemical activities," said Bevan. "Our detailed understanding of the biology underlying the production of these plant volatiles will now enable us to apply our new knowledge in agriculture in novel ways."
"We now are in the position to use this and previously identified genes of the biosynthetic pathway as tools to change volatile profiles in plants," said Tholl. "This approach can help us to design insect-induced volatile mixtures that are especially attractive to natural enemies used in biological pest control."
Another intriguing aspect of homoterpene volatiles is that they can elicit defensive responses in unattacked neighboring plants. "It may therefore be possible to exploit these signaling activities by priming defenses in crop fields prior to insect attack via specific transgenic 'emitter' plants," Tholl said.
The research was supported by a U.S. Department of Agriculture Cooperative State Research, Education, and Extension Service National Research Initiative Grant.
The article will be posted at http://www.pnas.org/content/early/recent sometime the week of November 15, 2010.
Learn more about research in the Tholl Lab at http://www.biology.vt.edu/faculty/tholl/
Susan Trulove | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
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NYSCF researchers develop novel bioengineering technique for personalized bone grafts
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A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
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The known Universe contains 100 billion galaxies grouped in superclusters and separated by empty space. This article explains what the Universe is, how it started, what it's made of, and what its future might be.
What the heck is the Higgs boson, and what's the Higgs field? This will be a lot easier to understand than you might think, and at the very least, you'll be able to sleep easier!
Milky way galaxy and its facts such it mass,components has been explained in this article.You can see milky way in Google earth as well.
Astronomers now tell us that planets not associated with any star roam in interstellar space. They also say that there are 100,000 times more rogue planets that there are stars in the galaxy. Hints such as MACHOS at the galactic fringe and microlensing of stars betray their existance.
Some require little science while others are pushing boundaries. Here is a sampling of all the different methods we know.
What did Einstein mean with his most famous equation? If you're having trouble sleeping and would like to know, here's a little help!
A nebula is a conglomeration of gases and dust in outer space. It is in nebulae that stars are born, and stars die. With the advent of large telescopes we have a better idea of these wondrous clouds that can be found light years away from Earth. View images and video of these magnificent creations.
In this article I attempt to answer the question about Where Earth is in the Universe. We go back into the past of the Universe to discover how the Universe began and we move outward from our own Solar System into the great beyond. To the edges of our existence and back again we will learn where we...
The theory of how everything we see, hear, smell, touch and feel may all be a holographic impression.
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