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To understand and control aging is the aspiration of many scientists. Researchers at the Biozentrum of the University of Basel have now discovered that the protein Gcn4 decreases protein synthesis and extends the life of yeast cells. Understanding how individual genes affect lifespan opens new ways to control the aging process and the occurrence of aging-related diseases. The results of this study have recently been published in “Nature Communications”.
For about one hundred years it has been known that nutrient restriction and moderate stress can significantly prolong life. The researchers led by Prof. Mihaela Zavolan and Prof. Anne Spang, both at the Biozentrum of the University of Basel, have discovered how the transcription factor Gcn4, a protein that regulates the expression of many genes, extends the life of baker’s yeast Saccharomyces cerevisiae. In various stress situations, the cells stimulate Gcn4 production which leads to reduced biosynthesis of new proteins and increased yeast lifespan.
Transcription factor represses protein synthesis
It has long been known that protein synthesis – also known as translation – plays an important role in aging. Inhibition of protein synthesis, caused for example by reduced nutrient intake, can have a positive effect on the life expectancy of diverse organisms such as yeast, flies, worms or fish. Reducing the ribosomes, the protein factories of the cell, can also considerably extend the lifespan of yeast cells.
What these cellular stresses have in common is that they activate the production of Gcn4. However, how this protein promotes longevity has remained unclear.
In their study, the team working with Zavolan exposed yeast cells to different stress conditions, measured their lifespan, protein synthesis rates and Gcn4 expression. “We observed that the level of the Gcn4 protein was positively correlated with the longevity of yeast cells,” says Mihaela Zavolan, Professor of Computational and Systems Biology.
“However, we wanted to understand why. We have now shown for the first time that it is the transcriptional suppression of genes that are important for cellular protein synthesis by Gcn4 that seems to account for its lifespan extension effect. As the translation machinery is limiting, the energy-intensive production of new proteins is overall dampened.” From the yeast cell’s point of view, this is an advantage: This enables them to live about 40 percent longer than usual.
Transcription factor is highly conserved in many organisms
The transcription factor Gcn4 is conserved in over 50 different organisms, including mammals, and it likely play a significant role in the aging of these organisms as well.
Zavolan’s group will now investigate whether the mammalian homolog similarly slows aging and extends lifespan by regulating protein synthesis genes in response to nutrients and stress.
Nitish Mittal, Joao C. Guimaraes, Thomas Gross, Alexander Schmidt, Arnau Vina-Vilaseca, Danny D. Nedialkova, Florian Aeschimann, Sebastian A. Leidel, Anne Spang, Mihaela Zavolan
The Gcn4 transcription factor reduces protein synthesis capacity and extends yeast lifespan
Nature Communications (2017), doi: 10.1038/s41467-017-00539-y
Prof. Dr. Mihaela Zavolan, University of Basel, Biozentrum, Tel. +41 61 207 15 77, email: firstname.lastname@example.org
Dr. Katrin Bühler, University of Basel, Biozentrum, Communications, Tel. +41 61 207 09 74, email: email@example.com
Dr. Katrin Bühler | 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
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The identical spacecraft, Voyager 1 and Voyager 2, were launched in the summer and programmed to pass by Jupiter and Saturn on different paths. Voyager 2 went on to visit Uranus and Neptune, completing the "Grand Tour of the Solar System," perhaps the most exciting interplanetary mission ever flown. Now NASA has announced that Voyager 1 -- about 11 billion miles from Earth -- has now sailed to the edge of the solar system and is expected to punch its way into interstellar space in the coming months or years. Voyager 2 is not far behind, but on a different trajectory.
University of Colorado Boulder scientists, who designed and built identical instruments for Voyager 1 and Voyager 2, were as stunned as anyone when the spacecraft began sending back data to Earth. The discoveries by Voyager started piling up: Twenty-three new planetary moons at Jupiter, Saturn, Uranus and Neptune; active volcanoes on Jupiter's moon, Io; Jupiter's ring system; organic smog shrouding Saturn's moon, Titan; the braided, intertwined structure of Saturn's rings; the solar system's fastest winds (on Neptune, about 1,200 miles per hour); and nitrogen geysers spewing from Neptune's moon, Triton.
Charlie Hord, a former planetary scientist at CU-Boulder's Laboratory for Atmospheric and Space Physics, remembers the salad days of the Voyager program, which was managed by NASA's Jet Propulsion Laboratory in Pasadena. Hord, the principal investigator for a time on the LASP instrument known as a photopolarimeter built for Voyager, still shakes his head in wonder as he recalls some of the discoveries.
"All of the scientists were dazzled by the pictures of the moons of Jupiter and Saturn coming back," recalled Hord, 74, who still lives in Boulder. 'To finally look at them up close was the most remarkable thing I've ever seen in my life." Since the early Voyager days were pre-Internet, "We used to send people over to the JPL news room to steal press kits so we could look at the pictures taken by the imaging team," he laughs.
The LASP photopolarimeter, a small telescope that measured the intensity and polarization of light at different wavelengths, was used for a variety of observations during the mission. The instrument helped scientists distinguish between rock, dust, frost, ice and meteor material. And it helped scientists determine the structure Jupiter's Great Red Spot, which Hord called "a giant hurricane that has blown for 200 hundred years," as well the properties of the clouds and atmospheres of Jupiter, Saturn Uranus and Neptune, and Saturn's largest moon, Titan.
The CU-Boulder instrument also was used to learn more about the make-up of the Io torus, a doughnut-shaped ring around Jupiter formed by volcanic eruptions from it's moon, Io, as well as determining the distribution of ring material orbiting Saturn, Uranus and Neptune and the surface compositions of the outer planet moons.
One of the finest mission moments for Hord was analyzing the data returned from the photopolarimeter when it was locked on the star Delta Scorpii as it emerged from behind Saturn and passed behind the elegant rings in a "stellar occultation" when the light from a star is blocked by an intervening object. The processed photopolarimeter data showed each ring was made up of numerous smaller ringlets. "They were beautiful -- they looked just like the grooves on a phonograph record," he said.
On the off chance either spacecraft is encountered by an alien civilization, each are carrying what are known as "Golden Records" -- gold-plated copper, audio-visual phonograph records with greetings in 50 languages, photos of people and places on Earth, the sounds of surf, wind, thunder, birds, and whales, diagrams of DNA and snippets of music ranging from Bach and Beethoven to guitarist Chuck Berry's classic rock-and-roll song, Johnny B. Goode. The spacecraft even carries a stylus set up in the correct position so that aliens could immediately play the record, named "Murmurs from Earth" by Carl Sagan, who conceived the Golden Record effort.
"I thought adding the Golden Record to the mission was a neat thing to do," said Hord. A guitar player himself who performs jazz and Big Band music with a trio that visits Boulder retirement homes, Hord recalled that JPL threw the Voyager team a party to celebrate the end of Voyager 2's Grand Tour as it passed by Neptune in 1989 (Pluto was in a distant part of its orbit at the time). "We even had Chuck Berry playing his guitar on the steps of the Jet Propulsion Laboratory," he said. "It was really something."
In 1990, Voyager 1 turned around one last time and took a portrait of the solar system -- a sequence of photos that revealed six of the nine planets in an orbital dance. From nearly 4 billion miles away, Earth took up only a single pixel.
"To me, Voyager was the most fun and interesting planetary mission ever," said Hord, who enlisted the help of then-graduate students Carol Stoker (now a NASA planetary scientist) and Wayne Pryor (now a professor at Central Arizona University) to analyze data from the mission. Over its lifetime, the CU-Boulder photopolarimeter science team also included LASP Professor Larry Esposito, Senior Research Associate Ian Stewart, retired faculty members Karen Simmons, Charles Barth and Robert West, as well as tireless work by many undergraduate and graduate students.
Esposito, who is still at LASP and is the principal investigator on a $12 million CU-Boulder instrument package aboard NASA's Cassini Mission to Saturn, said his biggest thrill of the Voyager mission was the Neptune fly-by in 1989 when the gas giant "went from being a small blurry dot to a planet with bright clouds and numerous moons and rings. "Triton erupted before our eyes, and Neptune's partial rings were punctuated and variable like a type of sausage that the French make."
Then-CU President Gordon Gee was so impressed with the blue image the LASP team made of Neptune's ring system that he used it on his Christmas cards, said Esposito, a professor in the astrophysical and planetary sciences department.
Esposito believes the biggest discovery by CU-Boulder's Voyager photopolarimeter team was the intricate structure of Saturn's F ring -- a ring he discovered in 1979 using data from NASA Pioneer 11 mission. The CU-Boulder team determined the faint F ring was made up of three separate ringlets that appeared to be braided together, and that the inner and outer limits of the ring were controlled by two small "shepherd satellites."
In addition, Esposito said that density waves -- ripple-like features in the rings caused by the influence of Saturn's moons -- allowed the team to estimate the weight and age of Saturn's rings.
As for Hord, the Casper, Wyo. native went on to be the principal investigator for two spectrometers designed for NASA's Galileo Mission to Jupiter that launched in 1989 to tour the Jovian system, including its bizarre moons. Hord officially retired in 1997, but returns to campus for occasional visits with his colleagues.
Rocketing at roughly 35,000 miles per hour, Voyager 1 will float within 9.3 trillion miles of the star AC+793888 in the constellation Camelopardalis in about 40,000 years. In 296,000 years, Voyager 2 will pass within 25 trillion miles of Sirius, the brightest star in the sky. Perhaps on the way, the spacecraft will encounter some musically inclined aliens up for a little Bach, Beethoven or Berry.
Larry Esposito | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
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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Ecosystems with high biodiversity are more productive and stable towards annual fluctuations in environmental conditions than those with a low diversity of species. They also adapt better to climate-driven environmental changes. These are the key findings environmental scientists at the University of Zurich made in a study of about 450 landscapes harbouring 2,200 plants and animal species.
The dramatic, worldwide loss of biodiversity is one of today's greatest environmental problems. The loss of species diversity affects important ecosystems on which humans depend.
Previous research predominantly addressed short-term effects of biodiversity in small experimental plots planted with few randomly selected plant species. These studies have shown that species-poor plant assemblages function less well and produce less biomass than species rich systems.
Extensive study with about 2,200 species in 450 landscapes
Researchers participating in the University Research Priority Programme “Global Change and Biodiversity” of the University of Zurich now demonstrate similar positive effects of biodiversity in real-world ecosystems in which mechanisms different from the ones in artificial experimental plots are at play. Using 450 different 1-km2 landscapes that spanned the entire area of Switzerland, they investigated the role of the diversity of plant, bird and butterfly species for the production of biomass, which was estimated from satellite data.
Biodiversity is important for the functioning of complex, natural ecosystems
“Our results show that biodiversity plays an essential role for the functioning of extensive natural landscapes that consist of different ecosystem types such as forests, meadows or urban areas”, study leader Pascal Niklaus from Department of Evolutionary Biology and Environmental Studies says.
The analyses showed that landscapes with a greater biodiversity were more productive and that their productivity showed a lower year-to-year variation.
Biodiversity promoted the adaptation of landscapes
The satellite data analysed by the scientists revealed that the annual growing period increased in length throughout the last 16 years, an effect that can be explained by climate warming. The prolongation in growing season was considerably larger in more biodiverse landscapes.
These relations were robust and remained important even when a range of other drivers such as temperature, rainfall, solar irradiation, topography, of the specific composition of the landscapes were considered.
“This indicates that landscapes with high biodiversity can adapt better and faster to changing environmental conditions,” Niklaus concludes.
Jacqueline Oehri, Bernhard Schmid, Gabriela Schaepman-Strub, and Pascal A. Niklaus. Biodiversity promotes primary productivity and growing season lengthening at the landscape scale. PNAS. 4 September 2017. DOI: 10.1073/pnas.1703928114
PD Dr. Pascal A. Niklaus
Department of Evolutionary Biology and Environmental Studies
University Research Priority Programme “Global Change and Biodiversity”
University of Zurich
Phone +41 44 635 34 13
Kurt Bodenmüller | Universität Zürich
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
Pollen taxi for bacteria
18.07.2018 | Technische Universität München
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
18.07.2018 | Health and Medicine | <urn:uuid:c4bebb66-66b7-40b6-a000-58ac4e4ea694> | 3.84375 | 1,223 | Content Listing | Science & Tech. | 29.826748 | 95,524,045 |
A team of researchers has found a way to detect trace gases down to concentrations at the parts-per-quadrillion level using a new variation on the photoacoustic effect, a technique that measures the sound generated when light interacts with molecules.
"In many ways, the photoacoustic effect is already the most practical method available for detecting pollutants in the atmosphere," said Gerald Diebold, a professor of chemistry at Brown University and coauthor of a new paper describing his lab's research.
"But when the concentration of the molecules you're trying to detect gets down to the parts-per-trillion level, the signal become too weak to detect. We've developed a new photoacoustic technique that boosts the signal and enables us to get down to the parts-per-quadrillion level, which to our knowledge is a record."
The study, which was a collaboration between Diebold's lab at Brown and the lab of Fapeng Yu at Shandong University in China, is published in the Proceedings of the National Academy of Sciences.
The photoacoustic effect takes place when a beam of light is absorbed by a gas, liquid or solid causing it to expand. The expansion is a mechanical motion that results in the launching of a sound wave. The effect was first discovered by Alexander Graham Bell in the 1880s but was of little practical value until the invention of the laser, which -- as a result of its typically narrow linewidth and high power -- made photoacoustic signals large enough to be easily detectable.
Photoacoustic detectors work by zapping a material with a laser tuned to a wavelength that is absorbed by the molecule of interest. In a typical photoacoustic experiment, the laser beam is switched on and off at a frequency that can be detected by a sensitive microphone to listen for any sound waves produced.
Different molecules absorb light at different frequencies, so by adjusting the frequency of the laser, it's possible to fine-tune a detector for specific substances. So to look for ammonia in air, for example, the laser would be tuned to the specific absorption frequency of ammonia molecules. One would then zap an air sample, and if the microphone picks up sound waves, that means the sample contains ammonia.
But the smaller the concentration of the target substance, the quieter the signal. So Diebold and his colleagues used an unconventional technique to boost the signal amplitude.
"What we've done is devise a method that relies on three different resonances," Diebold said. "The signal gets bigger with each resonance."
Instead of a single laser beam, Diebold and his colleagues combine two beams at a specific frequency and angle. The joining of the beams creates a grating -- a pattern of interference between the two beams. When the laser frequencies are tuned just right, the grating travels in a detection cell at the speed of sound, creating an amplification effect at each of the peaks in the grating.
The second resonance is created by a piezoelectric crystal used in the experiment, which vibrates precisely at the frequency of the combined laser beams. The small compressive forces in the pressure waves gradually induce motion in a crystal much in the same way that small, repeated pushes of a playground swing can cause a large amplitude motion of the swing.
The third resonance is generated by adjusting the length of the cavity in which the crystal is mounted so that it resonates when an integral number of half wavelengths of the sound exactly matches the cavity length. The output of the crystal, which is piezoelectric so that it generates a voltage proportional to its oscillatory motion, is sent to amplifiers and sensitive electronic devices to record the acoustic signal.
"One of the reasons that the moving grating method worked so well is that Professor Yu's group at Shandong University grew a special crystal that gives very large signals in response to the pressure waves," Diebold said. "We were told that it took them three months to synthesize the crystal."
In their experiments, the researchers showed that by using those three resonances, they were able to detect the gas sulfur hexafluoride in amounts down to the parts per quadrillion.
Diebold thinks the technique will be useful in developing detectors that are sensitive to very low pollutant gas concentrations, or for detecting molecules that have weak absorptions that make them inherently difficult to detect.
Diebold noted that in carrying out the experiments, he and his colleagues were "amazed to find that because the frequencies are so high -- in the hundreds of kilohertz range -- that there is virtually no background interference, either from electrical sources or from acoustic from room noise, wind or vibrations of a building. That means we can do experiments in an open cavity without having to block outside noise. So if you have a landfill and you're trying to detect methane, for example, you just take this detector, sit it there in open air and continuously monitor the output."
There remains some work on engineering a compact instrument before this technique can be used outdoors, but this study offers a convincing proof of concept, the researchers say.
Diebold's coauthors on the paper were Brown graduate students Lian Xiong and Wenyu Bai, along with Feifei Chen, Xian Zhao and Fapeng Yu from Shandong University in China. The research was funded in part by the U.S. Department of Energy (DE-SC0001082).
David Orenstein | 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
18.07.2018 | Health and Medicine | <urn:uuid:3805b542-f180-4a39-8fcf-9a3600e3a0b8> | 3.953125 | 1,756 | Content Listing | Science & Tech. | 41.516921 | 95,524,046 |
We can start by approaching the situation as a game.
Using centimeters can be a lot of fun when you roll dice to determine
lengths that must be drawn along a race course!
The end of the game shows that the chance
rolling of the dice has
determined which player finished first - plus - both players have a very good
measured approximation of the total course length. | <urn:uuid:3f7609d3-9f8f-43b7-886b-291168c161a5> | 2.59375 | 80 | Tutorial | Science & Tech. | 55.041364 | 95,524,055 |
Because cryptic fishes are difficult to accurately survey, they are undersampled components of coral reef habitats, and their ecological roles have been generally ignored. Fifty-eight enclosed stations were sampled in shoreline, nearshore reef, lagoon, backreef, forereef, and bank/shelf habitats with an ichthyocide (rotenone) at Buck Island Reef National Monument, St. Croix, U.S. virgin Islands. Our samples included 55 families and 228 species, 60 previously unreported from St. Croix. Fish assemblages varied across habitat zones with the shoreline assemblage the most distinct. Only 8% of the species were present in all habitats. Multi-dimensional scaling plots of habitat characteristics and Bray-Curtis similarities of fish assemblages revealed similar patterns. dominant and rare taxa are enumerated for each habitat sampled. Rotenone and visual census data are compared. While visual surveys accumulated more species per unit of effort, rotenone samples accumulated more species by area. Only 36% of the 228 species sampled with rotenone were visually detected, while 70% of the 115 species visually detected were also collected with rotenone. The use of rotenone is controversial but important for obtaining reasonably complete inventories of reef fishes. Misconceptions about rotenone and the advantages and limitations of alternative biodiversity assessment methods are discussed.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below | <urn:uuid:4376f22e-ea11-4e06-8177-5f98fd299f3e> | 3.296875 | 302 | Academic Writing | Science & Tech. | 16.851551 | 95,524,067 |
What do you do with the DNA sequence of an animal that has been extinct for tens of thousands of years? Well, if you are on the team of Professor Kevin Campbell (University of Manitoba, Canada), you go for the blood; specifically, the hemoglobin. In a study published in Nature Genetics (1), Professor Campbell’s team reports that they have successfully expressed the mammoth hemoglobin protein using the sequence from a 43,000 year-old mammoth specimen.
As it turns out, mammoth hemoglobin is pretty interesting, at least from an evolutionary biology/paleogenetic point of view. When the polypeptides from the α- and β-like globin genes of the mammoth were compared to those of the African (Loxodonta africana) and Asian (Elaphas maximus) elephants, there were only a few amino acids different in the genes, but these changes had pretty spectacular results on the physiochemical properties of the mammoth hemoglobin.
Hemoglobin binds and carries O2 in the blood. Hemoglobin’s affinity for O2 increases as temperature decreases. Because the process of releasing O2 (heme deoxygenation) is endothermic, the ability of hemoglobin to release, or off load, the O2 to the cells that need it is greatly reduced at lower temperatures. This means that heme deoxygenation results in an overall loss of heat that would be costly to an arctic mammal.
So how did an African-derived lineage come to survive so well in the arctic? Well, it turns out that the altered residues in the mammoth hemoglobin resulted a lower oxygenation enthalpy (Δh) compared to that of the Asian elephant. While mammals general have a Δh that cause small increases in temperature to result in large decreases in hemoglobin- O2 affinity, which helps site-specific O2 delivery to warmer exercising muscles, this is not the case for mammoth hemoglobin. Instead, Professor Campbell’s team found that the effects of changes in temperature on a mammoth’s hemoglobin affinity for O2 would be greatly reduced, thereby allowing the hemoglobin to release the O2 more easily at lower temperatures. This would have been an enormous energy advantage for the arctic-dwelling mammoth.
As if all this wasn’t cool enough on its own, there is also the wow factor of holding a plate of cells that are expressing a protein from the blood of an animal that last roamed the earth over 43,000 years ago. Just thinking about that gives me chills.
Campbell KL, Roberts JE, Watson LN, Stetefeld J, Sloan AM, Signore AV, Howatt JW, Tame JR, Rohland N, Shen TJ, Austin JJ, Hofreiter M, Ho C, Weber RE, & Cooper A (2010). Substitutions in woolly mammoth hemoglobin confer biochemical properties adaptive for cold tolerance. Nature genetics PMID: 20436470 | <urn:uuid:b3ffb0ca-62c3-4612-aded-b16f6afdd704> | 4.03125 | 619 | Nonfiction Writing | Science & Tech. | 33.900456 | 95,524,068 |
Scientists have identified four Antarctic glaciers that pose a threat to future sea levels using satellite observations, according to a study published in the journal Science.
Experts from the University of Edinburgh and University College London determined the effect that Antarctica and Greenland were having on global sea level in a comprehensive evaluation of the Earth’s ice sheets. They found that together these two ice-sheets were responsible for a sea level rise of 0.35 millimetres per year over the past decade – representing about 12 per cent of the current global trend.
However, despite recent attention that has focused on the importance of the Greenland ice sheet, the research shows that its glaciers are changing too erratically to establish a trend with confidence. In contrast, four major glaciers in East and West Antarctica were shown to be retreating in unison, raising concerns that global sea level could rapidly rise if the oceans continue to warm.
Dr. Andrew Shepherd, at the University of Edinburgh’s School of GeoSciences, said: "Our assessment confirms that just one type of glacier in Antarctica is retreating today – those that are seated in deep submarine basins and flow directly into the oceans. These glaciers are vulnerable to small changes in ocean temperature, such as those that have occurred over the 20th century, and those predicted for the 21st century. A rise of less than 0.5 ºC could have triggered the present imbalance."
Professor Duncan Wingham, at University College London, insists that the success of the research lies in the satellite instrumentation from which it is derived: "The extreme precision with which we can now make measurements of the Earth’s surface allows us to see the increasingly subtle changes within the ice sheets that will govern their future sea level contribution."
Tara Womersley | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science 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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New research could 1 day lead to heartier plants, better adapted to deal with climate change
Scientists have discovered a key molecular cog in a plant's biological clock – one that modulates the speed of circadian (daily) rhythms based on temperature.
Dr. Steve A. Kay confers with a student in his lab.
Credit: Emily Cavalcanti / USC Dornsife
Transcription factors, or genetic switches, drive gene expression in plants based on external stresses – such as light, rain, soil quality, or even animals grazing on them. A team of researchers at USC has isolated one, called FBH1, that reacts to temperature – tweaking the rhythm here and there as needed while in keeping it on a consistent track.
"Temperature helps keep the hands of the biological clock in the right place," said Steve A. Kay, dean of the USC Dornsife College of Letters, Arts and Sciences and the corresponding author of the study. "Now we know more about how that works."
Kay worked with lead author Dawn Nagel, a post-doc9/22/2014toral researcher at USC; and coauthor Jose Pruneda-Paz, an assistant professor at the University of California-San Diego, on the study, which was published by Proceedings of the National Academy of Sciences on Sept. 22.
Understanding the mechanics of how the interactions between the biological clock and the transcriptional network work could allow scientists to breed plants that are better able to deal with stressful environments – crucial in a world where farmers attempt to feed an increasing population amid urban development of arable land and a rising global temperature.
"Global climate change suggests that it's going to get warmer and since plants cannot run away from the heat, they're going to have to adapt to a changing environment. This study suggests one mechanism for us to understand how this interaction works," Nagel said.
Both plants and animals have transcription factors, but plants have on average six times as many – likely because they lack the ability to get up and walk away from any of their stressors.
"Plants have to be exquisitely tuned to their environment," Kay said. "They have evolved mechanisms to deal with things that we take for granted. Even light can be a stressor, if you are rooted to one location."
Among other things, Kay's research explores how these transcription factors affect plants' circadian rhythms, which set the pace and schedule for how plants grow.
Kay and his team conducted their research on Arabidopsis, a flowering member of the mustard family that is used as a model organism by scientists because of its high seed production, short life cycle, and the fact that now all of its genome has been sequenced.
This research was funded by the Ruth L. Kirschstein National Research Service Award (F32GM090375), and the National Instiutes of Health, National Institute of General Medical Sciences (R01GM056006, R01Gm067837, and RC2GM092412).
Robert Perkins | Eurek Alert!
Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung
Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg
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
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03.07.2018 | Event News
13.07.2018 | Event News
13.07.2018 | Materials Sciences
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Sunday, March 4, 2007
Explanation: If you took a picture of the Sun at the same time each day, would it remain in the same position? The answer is no, and the shape traced out by the Sun over the course of a year is called an analemma. The Sun's apparent shift is caused by the Earth's motion around the Sun when combined with the tilt of the Earth's rotation axis. The Sun will appear at its highest point of the analemma during summer and at its lowest during winter. Analemmas created from different Earth latitudes would appear at least slightly different, as well as analemmas created at a different time each day. The analemma pictured to the left was built up by Sun photographs taken from 1998 August through 1999 August from Ukraine. The foreground picture from the same location was taken during the early evening in 1999 July. | <urn:uuid:aff31713-7375-4353-82f8-0288c3f96eed> | 3.953125 | 181 | Personal Blog | Science & Tech. | 56.920588 | 95,524,131 |
Temperature and emission measure from goes soft X-ray measurements
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GOES (Geostationary Operational Environmental Satellite) X-ray sensors observe the Sun continuously in two broadband soft X-ray channels. These data are collected in real time and are used operationally to detect the onset and the intensity of solar flares. For these purposes it is usually sufficient to monitor only the soft channel (1–8 Å). The second, harder channel (0.5–4 Å) provides additional information on the state of the coronal plasma. The dual X-ray measurement data are archived and made available to external users for basic research.
The GOES X-ray sensors operate on the ion-chamber principle: measured ion-chamber electric current is proportional to the net ionization rate caused by incident X-ray flux on encapsulated noble gases. The ratio of the outputs of the two channels in electric current, therefore, is uniquely a function of the color temperature of the emitting plasma, and the magnitude of each of the currents is proportional to a quantity, known as the emission measure, that convolves the volume and the density of the emitting plasma.
This paper provides a detailed description of the procedure used for computing color temperature and emission measure from GOES X-ray data, including a table of constants for SMS and GOES X-ray sensors that are necessary for reducing the archived data from these satellites. Temperature and theoretical current tables were constructed, for individual GOES sensors, from laboratory calibrations of instrument responses and from synthetic solar X-ray spectra generated by two models of solar thermal X-ray emission: Raymond-Smith and Mewe-Alkemade. Example tables are shown and others are available on request.
Errors that may be incurred from the use of GOES X-ray data in the computation of flare temperatures and emission measures may be classified under four major groups: instrumentinduced errors, including errors of calibration and random measurement errors; environmentally induced errors, due primarily to the ambient energetic electron background; solar influences, including the consequences of the isothermal assumption and the single-source assumption; and uncertainties in the modelled solar synthetic spectrum. These error sources are discussed separately, and a rough estimation of the collective error is made where this is quantitatively feasible. Finally, temperatures and emission measures are computed from GOES data and are compared with those derived from SMM andHinotori soft X-ray spectrometer data and from broadband photometric data from the PROGNOZ satellite.
KeywordsFlare Emission Measure Color Temperature Synthetic Spectrum Random Measurement Error
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Factors in the Energy Budget of Mountain Hummingbirds
The abundant flowers of a compressed summer in the mountains provide an energy resource for exploitation by hummingbirds. However, the cold nights constitute a liability in their total energy budget. Adiabatic cooling, clear dry air, and the heat sink of the cold sky result in chilling conditions for the incubation of eggs by a tiny hummingbird. Howell and Dawson (1954) recorded the ability of the Anna’s hummingbird (Archilochus anna) to maintain homeothermy while incubating overnight. I was greatly impressed the first time that I saw an even smaller calliope hummingbird (Stellula calliope) incubating her eggs in the presunrise cold of Jackson Hole, Wyoming. In a later visit I was equipped to record temperatures from two calliope nests. They also maintained homeothermy all night, despite the colder climate (Calder, 1971), stimulating my interest in heat-exchange principles and problems. It was obvious that ornithologists had given little consideration to physical factors in bird behavior, and that further study of hummingbird nesting would be rewarding. The population of broad-tailed hummingbirds (Selasphorus platycercus) at Gothic, Colorado, has been ideal for this. Evidence of the marginal energetic situation for this population may be seen in the occasional recourse to hypothermia during incubation (Calder and Booser, 1973) and the abandonment of live, normal chicks at some late nests when the flower supply declines, simultaneous with influx of competing migrant hummingbirds, in late July and early August (Calder, 1973d). Thus energy conservation in thermoregulation is of major importance.
KeywordsHeat Output Radiative Heat Loss Nest Temperature Cold Night Radiative Heat Exchange
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FTIR may also refer to Frustrated total internal reflection. For other uses of this kind of technique, see Fourier-transform spectroscopy. Fourier-transform spectroscopy is a less intuitive way to obtain the same information. Rather than shining a monochromatic beam of light at the sample, what is ftir pdf technique shines a beam containing many frequencies of light at once and measures how much of that beam is absorbed by the sample.
Next, the beam is modified to contain a different combination of frequencies, giving a second data point. The beam described above is generated by starting with a broadband light source—one containing the full spectrum of wavelengths to be measured. The light shines into a Michelson interferometer—a certain configuration of mirrors, one of which is moved by a motor. The raw data is sometimes called an “interferogram”.
The first low-cost spectrophotometer capable of recording an infrared spectrum was the Perkin-Elmer Infracord produced in 1957. This instrument covered the wavelength range from 2. Commercial spectrometers use Michelson interferometers with a variety of scanning mechanisms to generate the path difference. Common to all these arrangements is the need to ensure that the two beams recombine exactly as the system scans.
The simplest systems have a plane mirror that moves linearly to vary the path of one beam. In this arrangement the moving mirror must not tilt or wobble as this would affect how the beams overlap as they recombine. Interferometer schematics where the path difference is generated by a rotary motion. Systems where the path difference is generated by a rotary movement have proved very successful. One common system incorporates a pair of parallel mirrors in one beam that can be rotated to vary the path without displacing the returning beam. Another is the double pendulum design where the path in one arm of the interferometer increases as the path in the other decreases.
A quite different approach involves moving a wedge of an IR-transparent material such as KBr into one of the beams. Increasing the thickness of KBr in the beam increases the optical path because the refractive index is higher than that of air. One limitation of this approach is that the variation of refractive index over the wavelength range limits the accuracy of the wavelength calibration. The interferogram has to be measured from zero path difference to a maximum length that depends on the resolution required. In practice the scan can be on either side of zero resulting in a double-sided interferogram. Mechanical design limitations may mean that for the highest resolution the scan runs to the maximum OPD on one side of zero only. The interferogram is converted to a spectrum by Fourier transformation. | <urn:uuid:d6cbd849-c0ec-4f0a-b531-d455ec3ac2b1> | 3.78125 | 556 | Knowledge Article | Science & Tech. | 34.557107 | 95,524,146 |
|Aequorea coerulescens medusa (Aequoreidae)|
Conica are a cnidarian suborder of the Leptomedusae (thecate hydroids). They make up the bulk of their order; their internal relationships are not well resolved, and most of the roughly 30 families are not yet assigned to a superfamily.
They are named for the distinctive shape of their hypostome, the "tip" of the polyps' body where the mouth is located. As opposed to the smaller thecate suborder Proboscidoidea with their elongated hypostome, the Conica have a simple hypostome without a pregastric cavity and a shape that is generally round or conical.
Well-known members of the Conica are the "air fern" (Sertilaria argentea) of the Sertulariidae which is sold dried as novelty "plants" and aquarium ornaments, and the Crystal Jelly (Aequorea victoria) of the Aequoreidae, a bioluminescent hydrozoan.
Apart from the families assigned to the three named superfamilies, there are many Conica that are presently unassigned as to superfamily, either because their relationships and/or validity remain unknown or because they represent minor but very ancient ancient lineages basal to the three main radiations within this order:
- Family Aequoreidae
- Family Barcinidae
- Family Clathrozoellidae (often included in Clathrozoidae or placed in Anthomedusae)
- Family Clathrozoidae Stechow, 1921
- Family Dipleurosomatidae
- Family Eirenidae (including Eutimidae, Timoididae)
- Family Haleciidae
- Family Lafoeidae (including Hebellidae)
- Family Laodiceidae
- Family Lovenellidae (including Eucheilotidae)
- Family Malagazziidae
- Family Melicertidae
- Family Mitrocomidae Haeckel, 1879
- Family Octocannoidae
- Family Orchistomatidae
- Family Phialellidae
- Family Sugiuridae
- Family Syntheciidae
- Family Teclaiidae
- Family Tiarannidae
- Family Tiaropsidae Boero, Bouillon & Danovaro, 1987
- Family Zygophylaxidae (often included in Lafoeidae)
Superfamily Campanulinoidea (disputed)
- Family Blackfordiidae
- Family Calycellidae (often included in Campanulinidae)
- Family Campanulinidae
- Family Lineolariidae (often included in Campanulinidae)
Superfamily Plumularioidea (4 families)
- Schuchert (2008)
- Schuchert (2008), MarineSpecies.org (2008)
- MarineSpecies.org (2008): Conica. Retrieved 2008-JUL-08.
- Schuchert, Peter (2008): The Hydrozoa Directory - Suborder Conica Broch, 1910. Retrieved 2008-JUL-08.
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Species Detail - Sylvicola cinctus - Species information displayed is based on the dataset "Anisopodidae and Thaumaleidae (Diptera: Nematocera) of Ireland".
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).
Anisopus withycombei, Rhagio cinctus, Sylvicola withycombei
insect - true fly (Diptera)
4 January (recorded in 2002)
29 July (recorded in 1924)
Irish Biogeographical Society, Anisopodidae and Thaumaleidae (Diptera: Nematocera) of Ireland, National Biodiversity Data Centre, Ireland, Sylvicola cinctus, accessed 19 July 2018, <https://maps.biodiversityireland.ie/Dataset/2/Species/88024> | <urn:uuid:587489e2-3743-4167-ad5f-369fd75ecf6e> | 2.8125 | 220 | Structured Data | Science & Tech. | 4.79202 | 95,524,166 |
Bacteria Make Diesel from Biomass
Newly engineered E. coli streamline the conversion of cellulose into fuel.
Engineered bacteria have been rewired with the genetic machinery necessary to convert cellulose into a range of chemicals, including diesel fuel. The bacteria, developed by South San Francisco company LS9 in collaboration with researchers at the University of California, Berkeley, make the necessary enzymes for every step along the synthesis pathway and can convert biomass into fuel without the need for additional processing. LS9 has demonstrated the bacteria in pilot-scale reactors and plans to scale the process to a commercial level later this year.
Jay Keasling, professor of chemical engineering and bioengineering at UC Berkeley and one of LS9’s founders, and scientists at LS9 report engineering E. coli bacteria to synthesize and excrete the enzyme hemicellulase, which breaks down cellulose into sugars. The bacteria can then convert those sugars into a variety of chemicals–diesel fuel among them. The final products are excreted by the bacteria and then float to the top of the fermentation vat before being siphoned off.
Using these methods, it’s possible to create a range of fuels from biomass, but LS9 is focusing on diesel rather than fuels similar to gasoline for the time being, says Stephen del Cardayre, the company’s vice president of research and development. Diesel specifications are easier to meet and the market for diesel is growing by 2 to 4 percent a year, while that for gasoline is flat. Last May, LS9 partnered with Procter & Gamble to develop fuels as well as commodity chemicals.
The effort by LS9 is part of an increasing push by bioengineers to bring down the cost of biofuels by developing microbes that can turn biomass, such as switchgrass and agricultural waste, into fuels without any additional processing that would require expensive catalysts and high temperatures. Microbes can typically complete only part of the conversion, requiring post-processing to convert the chemical precursors made by the microbes. The newly engineered E. coli “are a singular vehicle that can accomplish all this at once, providing a very efficient process to make products already on the market,” says David Berry, a partner at Flagship Ventures, which cofounded LS9.
LS9’s process is built on E. coli bacteria’s metabolic machinery for converting sugars into fatty acids, which they then use to make other molecules. The advantage of working with E. coli is that the organism, a workhorse of molecular biology, is well known and easy to grow, says Keasling. And the bacterium’s fatty acid pathway is more efficient at turning feedstocks into fuel than metabolic pathways used by other synthetic biology companies.
Fatty acids are a large class of molecules that can form the basis of many commodity chemicals and fuels that are conventionally derived from petroleum. These metabolic pathways are complex networks, and taking advantage of them required changing several of the bacterium’s existing genes as well as adding new ones. After years of engineering, says Keasling, “we can get the molecule we want specifically.”
Del Cardayre says LS9 has tested the diesel-production process at its 1,000-liter pilot-scale plant in South San Francisco using sugarcane as a feedstock. The company will scale the process to a commercial level at a 75,000-liter plant this year.
LS9 isn’t the only company turning sugarcane into diesel: last year, another synthetic biology company founded by Keasling, Amyris Biotechnologies of Emeryville, CA, opened a demonstration plant in Campinis, Brazil. Amyris’s process is based around yeast engineered to convert sugars into hydrocarbon-fuel precursors. Del Cardayre says LS9 may open a plant in Brazil as well, but because the new bacteria can convert cellulose, not just sugar, the company isn’t tied to sugarcane or any other feedstock.
Jim Collins, professor of biomedical engineering at Boston University, says the question now is whether LS9’s process will be cost-effective on a large scale. “As you go from 10 gallons to thousands of gallons, the biology changes, and analyses that worked well in the lab no longer work,” notes Collins, because the microbes’ environment changes. “The interesting question in the next few years is, which company can get their yields high enough, and get their processes up to scale to keep costs down,” says Collins.
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:036cac4f-6af2-4787-b61b-421204477f8b> | 3.125 | 979 | Truncated | Science & Tech. | 34.706646 | 95,524,171 |
'Genetic toolkit' will help shed light on which species survive climate change
Coral reefs - stunning, critical habitats for an enormous array of prized fish and other species - have survived five major extinction events over the last 250 million years.
Now, an international team of scientists led by Rutgers faculty has conducted the world's most comprehensive analysis of coral genes, focusing on how their evolution has allowed corals to interact with and adapt to the environment. A second study led by Rutgers researchers with colleagues at the University of Hawaii shows -- for the first time -- how stony corals create their hard skeletons, using proteins as key ingredients.
"There are a few key genes in corals that allow them to build this house that laid down the foundation for many, many thousands of years of corals," said Debashish Bhattacharya, a professor in the Department of Ecology, Evolution and Natural Resources in the School of Environmental and Biological Sciences at Rutgers. "It couldn't be any more fundamental to ocean ecosystems."
"I think one of the more interesting aspects of these data will be to understand which coral species may become winners or losers in the face of anthropogenic climate change - what makes them tougher and what makes them susceptible to changes in temperature, changes in ocean acidification," said Paul Falkowski, a professor who leads the Environmental Biophysics and Molecular Ecology Laboratory at Rutgers.
The coral gene database study, led by Bhattacharya and Falkowski, was published today in the journal eLife. The study stems from an international coral genomics symposium and workshop held at Rutgers in February 2014 that was funded by the National Science Foundation. The stony coral study was published in the Proceedings of the Royal Society B: Biological Sciences last month.
Nearly all corals are colonial organisms that consist of as many as hundreds of thousands of animals called polyps. Types of corals include stony, shallow-water species that build reefs, soft corals and deep-water corals that live in dark cold waters, according to the National Oceanic and Atmospheric Administration.
Corals face four major threats from humans: Destruction of reefs by grenades and poison used to kill fish for food; nutrient pollution, usually from sewage or agricultural runoff, that overstimulates harmful algae; increased heat in the upper ocean, which causes most coral bleaching that can kill reefs; and acidification of the ocean, according to Falkowski.
"Corals are the most diverse marine ecosystems on the planet," he said. "But their value to marine ecosystems -- and to our own use of marine resources -- is very underappreciated."
Recent aerial and underwater surveys have found that 93 percent of the Great Barrier Reef off Queensland in Australia has endured very severe, moderate or at least some coral bleaching this year, according to the ARC Centre of Excellence for Coral Reef Studies in Australia. The reef, a world-renowned tourist attraction, is about 1,430 miles long.
Elevated sea temperatures from global warming can cause corals to expel tiny, colorful algae, according to the center. Corals turn translucent and white when they lose the algae. Mildly bleached corals can recover if the temperature drops and algae can recolonize them. If not, corals may die.
At Rutgers two years ago, leaders in the field of coral biology and genomics met to plan an analysis of 20 coral genomic datasets. The goal was to provide a comprehensive understanding of coral evolution since the organisms appeared on Earth 525 million years ago. The coral database, which includes corals in tropical waters, has been posted on the comparative.reefgenomics.org website to foster growth in this important area of research.
The eLife study's major advances include explaining the origin and evolution of the unique genes involved in the creation of hard skeletons by corals. The study also serves as a novel toolkit compared with the genes of humans, shellfish and other animals with hard skeletons.
Bhattacharya and coauthors found dozens of genes that allow corals to coordinate their response to changes in temperature, light and pH (acidity vs. alkalinity) and deal with stress triggered by the algae that live with them and exposure to high levels of light.
Surprisingly, some of these stress-related genes are of bacterial origin and were acquired to help corals survive. An intriguing theory that arose from the study is that the vast genetic repertoire of corals may help them adapt to changing ocean conditions.
The study in the Proceedings of the Royal Society B: Biological Sciences -- led by former Rutgers Department of Marine and Coastal Sciences post-doctoral fellow Tali Mass -- explains how stony corals make their hard, calcium carbonate skeletons. It also explains how this process might be affected as the oceans become more acidic due to climate change. Acidity increases as oceans are exposed to higher concentrations of carbon dioxide, the main greenhouse gas and cause of climate change, in the atmosphere.
"The aragonite (hard skeleton) is not just minerals," Bhattacharya said. "The proteins are very important for giving it shape and making it stable."
Falkowski said the study serves as a model for understanding how we can regenerate bone. "There are amazing parallels between the production of the skeleton of coral and production of bone," he said.
Todd B. Bates | EurekAlert!
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science 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
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NASA has confirmed its upcoming Mars 2020 rover will carry a small robotic passenger. The agency has been working on a helicopter drone for use on Mars, and it now plans to include this vehicle with the 2020 rover. The still-unnamed Mars helicopter will be the first heavier-than-air craft to fly on another planet. In doing so, it will help the 2020 rover mission cover more ground and learn more about Mars.
Thus far, all our explorations of Mars have taken place from space or on the surface with rovers. Flying on Mars is challenging for several reasons. First of all, the atmosphere is only one percent the density of Earth’s. That makes fixed-wing aircraft impractical, and helicopters need to have low mass and comparatively large and fast-spinning blades. NASA has tested the helicopter prototype in a Mars-like atmosphere, proving that it will be able to take flight on the red planet. However, flying on Mars is inherently more dangerous than rolling around. If the helicopter tips over during landing or falls out of the sky, it won’t be possible to repair it from millions of miles away.
The Mars helicopter will ride to the planet attached to the underside of the 2020 rover. After the wheeled vehicle is on the planet’s surface, NASA will find a suitable location to deploy the helicopter. The rover will lower the helicopter onto the ground, allowing it to deploy and begin charging with its solar panels. When it’s ready to take flight, the aircraft will need to operate autonomously.
Mars is several light-minutes away, so it’s impossible to control the helicopter’s flight path or landing in real time. NASA will relay general commands to the rover, which communicates with the helicopter. On its first flight, the vehicle will make a short vertical climb to 10 feet (3 meters) and remain there for 30 seconds before landing. Four additional tests will take place over the course of a month, some of which will take the helicopter hundreds of meters high for flights as long as 90 seconds.
NASA hopes to use the Mars helicopter to scout ahead for the 2020 rover. Since it too cannot be controlled in real time, having detailed data on the terrain will help NASA plot longer, safer courses for the rover. The helicopter is considered a high-risk, high-reward endeavor. If it crashes or doesn’t work as well as hoped, the 2020 rover will still operate normally. If it does work, NASA will be able to build on the design for future Mars missions. | <urn:uuid:8fef6ffe-0828-4b29-aebc-45fc23d060c4> | 3.5625 | 521 | News (Org.) | Science & Tech. | 55.366212 | 95,524,205 |
1. State which atom is larger according to periodic trends. Explain the difference for each of the pairs.
a) Br, F
b) Ca, Mg
c) C, Si
d) He, Ar
2. State which atom has a smaller first ionization energy according to periodic trends. Explain the difference in ionization energy for the pairs.
a) O, S
b) K, Na
c) Cd, Zn
d) Al, Ga
3. Which of the following is smaller? Explain the trend.
a) Mg, Mg2+
b) Al, Al3+
c) Cs, Cs+
4. Arrange in order of increasing size and explain the trend.
a) Fe, Fe 2+, Fe3+
b) Ti, Ti3+, Ti4+
5. Arrange in order of increasing size:
Br-, Ca2+, Cl-, F-, Li+, Mg2+, N3-, Na+, O2-, Rb+, S2-
6. Given the following data:
2NO(g) ---> N2(g) + O2(g) (delta)H= -180.6 kJ
N2(g) + O2(g) + Cl2(g) -----> 2NOCl(g) (delta)H= +103.4 kJ
Find the ?H for the following reaction:
2NOCl(g) ----> 2NO(g) + Cl2 (g)
7. During the discharge of a lead-acid storage battery, the following chemical reaction takes place:
Pb + PbO2 + 2H2SO4 ----> 2PbSO4 + 2H2O
Using the following two reactions:
Pb + PbO2 + 2SO3 ------> 2PbSO4 (delta)H(degrees)= -775 kJ
SO3 + H2O ---> H2SO4 (delta)H(degrees)= -113 kJ
Determine the enthalpy of the reaction for the discharge reaction above.
*The delta triangle symbol and the degrees symbol are written out.© BrainMass Inc. brainmass.com July 23, 2018, 12:21 am ad1c9bdddf
The solution is attached below in two files. The files are identical in content, only differ in format. The first is in MS Word format, while the other is in Adobe pdf format. Therefore you can choose the format that is most suitable to you.
If the atoms share the same group (column) in the periodic table, the larger the atomic number (the number of protons), the larger the atom.
Br (Bromine) atom is larger than F (Fluorine) atom.
Bromine has 35 protons in its nucleus (and 35 electrons around it)
Fluorine has 9 protons and 9 electrons.
They both share the same column in the periodic table (17), and as we go down (increasing the number of the period) the size of the atoms increases.
Ca (Calcium) atom is larger than Mg (Magnesium) atom.
Calcium has 20 protons in its nucleus.
They both share the same column in the periodic table (2).
Si (silicon) atom is larger than C (carbon) atom.
Carbon has 6 protons in its nucleus.
Silicon has 14 protons.
They both share the same column in the periodic table (14).
Ar (Argon) atom is larger than He (Helium) atom.
Helium has 2 protons in its nucleus.
Argon has 10 protons
They both share the same column in the periodic table (18)
First ionization energy is related to the outer shell (valence) electrons affinity. it measures how easy it is to remove an electron from the atom.
As the number of the group (column) increases, so is the electrons affinity increases, so it is harder to pull an electron out.
Alkali metals (group 1) have only one valence electron and they readily give it away
Noble gasses (group 18), on the other hand, have 8 electrons in ...
The solution examines thermochemistry and periodic properties of elements. | <urn:uuid:d75dbbbd-4170-4e86-9e60-d95c6a901cf7> | 3.84375 | 919 | Tutorial | Science & Tech. | 77.744346 | 95,524,222 |
Geologists have warned that deadly earthquakes could become more frequent in the coming year and that they are likely to be caused by the slowing down of the Earth's rotation.
"The correlation between Earth's rotation and natural disaster activity is strong and suggests there is going to be an increase in numbers of intense earthquakes next year", Bilham told the Observer last week.
As the Earth rotates on its axis once in a roughly 24 hour period, a slowdown in rotation thus impacts the length of a day.
The warnings from experts came just days after a strong quake measuring 7.3 on the Richter scale hit the Iran-Iraq border resulting in the death of more than 530 people. As they say, they found (approximately every 30 years) with a significantly higher frequency of severe earthquakes, about 25 to 30 per year, compared with about 15 earthquakes averaging over the other periods. In a study published in August in Geophysical Research Letters, geophysicists Rebecca Bendick of the University of Montana and Roger Bilham of the University of Colorado claim to have found a correlation between changes in the Earth's rotation and seismic activity. "We have had it easy this year", the Guardian reported he said.
"Consequently", Bilham said, "we will see a significant increase in the numbers of major earthquakes over time".
"The rotation of the Earth does change slightly - by a millisecond a day sometimes - and that can be measured very accurately by atomic clocks", said Bilham.
But while scientists may have found a pattern that will allow them to predict periods of significant seismic activity, there's still no way to predict when or where an natural disaster will happen.
"The pair found that the Earth's rotation began one of its "slow" periods, indicating that more earthquakes are on the way". "The Earth is offering us a five-year heads-up on future earthquakes", said Bilham.
"The inference is clear". If the two geophysicists' research is correct, 2018 should bring a significant increase in the number of major earthquakes. This year we made it clean.
"We could easily have 20 a year starting in 2018".
Scientists have long known that tidal friction caused by the moon's effect on Earth is gradually causing the Earth's rotation to slow. Until now, we only had six powerful earthquakes.
In addition, it is hard to predict where these extra earthquakes will occur, although Bilham said they found that most of the intense earthquakes that responded to changes in day length seemed to occur near the equator.
Mulvaney: Pass-through entities need to be addressed in tax reform
Despite his silence on Moore, Trump on Thursday seized upon an allegation of sexual misconduct against Sen. You work for NBC News in Washington D.C.
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- Évacuation de l'ancienne Ecole des Beaux-Arts de Nantes — Nantes | <urn:uuid:f2c1ee03-b929-4efb-bb82-153d25b8369c> | 3.40625 | 727 | News Article | Science & Tech. | 45.473028 | 95,524,233 |
UAV Spectral Image Mapping of Shoreline Vegetation - 04/07/2018
Identification Based on Visible Spectral Bands
Rapid identification of a clear water surface, shoreline and vegetation can serve as a means of monitoring of the water level and as an important indicator of changes. In cases when a high level of detail or on-demand data collection is required, unmanned aerial vehicles (UAVs or ‘drones’) can provide a good service. It is important to think about the costs of the UAV and the connected sensors as well. Multispectral and thermal cameras are still very expensive in comparison to visible cameras. This article shows how a commercially available middle-class drone (DJI Phantom 3 with built-in camera), which collects data only in the visible spectral bands and is affordable even for individuals, can be easily used to calculate colour spectral indices to identify shoreline, vegetation and water.
An area lying to the north of the city of Pardubice in the Czech Republic is very rich in ponds. The area of interest is flat, lying approximately 220 metres above sea level. It comprises clear water surfaces, seasonally flooded greenery, vegetation including treetops, dry reeds (including dry grass) and dry trees (see Figure 1).
Flight Planning and Data Collection
The dataset was captured on 20 April 2018, i.e. in spring. The flight was planned in advance in DJI GO and then sent to the drone. The drone automatically flew according to the plan. It took approximately 15 minutes to cover the area of 0.0285km2 so no break in the flight was necessary. The total length of the flight was 1,545m, and it was planned in seven main lines consisting of 64 waypoints in total. Front and side overlap were both 60%. Average speed was 2.2m/s, altitude was 39.6m and resolution was 1.7cm per pixel.
Data Processing to Calculate Vegetation Indices
Two software tools were used: Pix4Dmapper 4.2.27 trial and ArcGIS for Desktop 10.5.1. Pix4Dmapper was used for a mosaic building and calculating all indices. ArcGIS was used for visualisation of the resulting indices. WGS 84 – UTM zone 33N was used as a coordinate system.
The final mosaic was created from 33 images, covering 0.012km2. Certain types of land cover require a higher overlap, so images showing only treetops were not aligned because of the lack of common points. Nevertheless, the final mosaic covered the whole shoreline so it was perfectly usable for the next step.
The survey team calculated various colour-based vegetation indices, which are based only on red, green and blue bands: CIVE, ExG, ExR, GRVI, NDI, TGI, VARI and VDVI. Several colour band combinations and combinations of particular indices were calculated as well to include different approaches described in the literature.
ArcGIS was used for visualisation of the results because it provides more visualisation methods and better tools for map creation. The “Pink to YellowGreen Diverging, Bright” colour ramp was used for all indices, which helped to visually distinguish between particular land cover types. The other settings were: stretched visualisation, percent clip stretch (both min. and max. 0.5). Green colour represents the highest values, dark pink represents the lowest values, and yellow represents medium values in all cases to simplify comparison of the results. An inverted scale would be more natural in some cases, e.g. for displaying vegetation with the green colour.
Results and Interpretation
Based on the visual interpretation and literature, the following colour indices were chosen as the most suitable ones: CIVE, ExG – ExR, NDI, Red/Green ratio and VDVI (see Figure 2 for results and Figure 3 for calculating algorithms).
The clear water surface is highlighted by R/G, ExG – ExR (dark green in both cases) and NDI (dark pink). The water surface can be easily distinguished from the seasonally flooded greenery. The borderline between the clear water surface and seasonally flooded greenery is indiciated by the yellow line. Green vegetation is highlighted by all indices. VDVI and CIVE clearly highlight treetops, displaying green and dry vegetation in dark colours so that these two types of land cover can be easily distinguished. Seasonally flooded greenery is well visible with R/G, NDI, ExG – ExR and VDVI because it is bordered by a yellow line. The best result is provided by VDVI (green colour). Dry reeds and dry trees are well highlighted by VDVI (dark pink) and CIVE (dark green).
Comments on the Indices
VDVI is very useful for differentiating green vegetation from dry vegetation. R/G (and its opposite G/R) makes it easy to distinguish between vegetation and the clear water surface. The ExG – ExR difference makes it possible to distinguish all vegetation from the clear water surface. NDI makes it possible to distinguish all vegetation from the clear water surface. CIVE clearly highlights green vegetation, which can be easily distinguished from dry vegetation (both trees and reeds). The clear water surface cannot be easily distinguished because it is visualised in a similar way as dry vegetation.
Shoreline, vegetation and the clear water surface can be easily monitored by a middle-class UAV equipped with a camera recording only in the visible spectral bands. It provides data with a very high spatial resolution on demand and at acceptable costs. It can significantly help with monitoring of less accessible areas such as overgrown or waterlogged terrain, as in this case. Particular land cover types can be easily distinguished by a visual interpretation as the first step. Vegetation indices based on visible spectral bands appropriately complement the visual interpretation. They can quickly highlight vegetation, seasonally flooded vegetation and the clear water surface to enable identification of the shoreline as well. Each index emphasises different types of land cover so it is beneficial to combine multiple indices.
This research was supported by the University of Pardubice, Project SGS_2018_19.
Hamuda, E., Glavin, M., Jones, E. (2016) A survey of image processing techniques for plant extraction and segmentation in the field. Computers and Electronics in Agriculture 125(C), pp. 184–199.
Meyer, G.E., Neto, J.C. (2008) Verification of color vegetation indices for automated crop imaging applications. Computers and Electronics in Agriculture 63(2), pp. 282–293.
Ponti, M.P. (2013) Segmentation of Low-cost Remote Sensing Images Combining Vegetation Indices and Mean Shift. IEEE Geoscience and Remote Sensing Letters 10(1), pp. 67-70.Last updated: 16/07/2018 | <urn:uuid:53a53352-15fb-4ea4-be06-284458070594> | 2.96875 | 1,446 | Academic Writing | Science & Tech. | 46.195664 | 95,524,244 |
Trees, particularly those with deep roots, contribute to the Earths climate much more than scientists thought, according to a new study by biologists and climatologists from the University of California, Berkeley.
While scientists studying global climate change recognize the importance of vegetation in removing carbon dioxide from the atmosphere and in local cooling through transpiration, they have assumed a simple model of plants sucking water out of the soil and spewing water vapor into the atmosphere.
The new study in the Amazonian forest shows that trees use water in a much more complex way: The tap roots transfer rainwater from the surface to reservoirs deep underground and redistribute water upwards after the rains to keep the top layers moist, thereby accentuating both carbon uptake and localized atmospheric cooling during dry periods.
Robert Sanders | 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.
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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Geothermal energy is, literally, the heat of the earth. The heat itself derives from radioactive decay beneath the earth's surface and, in certain locations, it is concentrated enough and is close enough to surface waters to be brought to the surface for a variety of purposes. When it is above 150 degrees C (302 F), it is usually considered hot enough to be used to generate electricity as it is in Italy, El Salvador, Mexico, Japan, Iceland, and Indonesia, among other countries. No such operations exist in Arizona, but several power plants are currently in operation just west of Yuma, Arizona in the Imperial Valley of southeastern California. Although some high temperature geothermal resources exist southeast of Phoenix near the now-retired Williams Air Force Base, they have never been deemed economically feasible.
Resources less than 150 degrees C, have wide non-electric applicability. Indeed, the worldwide potential of such temperatures is many times larger than that used to generate electricity. Such temperatures are used in greenhouses, hot baths, onion dehydration, laundries, and even hotel space heating. The capital of Iceland is almost entirely heated with geothermal water. Several heating districts exist in the US, although none are as large as those in Iceland. These include projects in Reno, Klamath Falls, Boise, Susanville, and other locations. The best source of information in the US on such non-electric applications is the Oregon Institute of Technology Geo-Heat Center.
In Arizona, the opportunity to use geothermal water is limited, in part by population distribution, yet at least three locations are well known. These are Buckhorn Baths in Apache Junction, Castle Hot Springs in the Bradshaw Mountains, and Childs on the Verde River. Additionally, the two highest temperature springs in the state are Clifton and Gillard, both in the Clifton-Morenci area of southeastern Arizona. The water temperature at these springs ranges from 158-180 degrees Fahrenheit. Even though temperatures may exceed 284 degrees Fahrenheit at depth, these two sites are only suitable for low grad steam.
The only types of geothermal energy to be commercially developed are those called "hydrothermal". These include steam, as developed at The Geysers (north of San Francisco), and liquid, as developed in southeastern California. Geothermal energy is also available in several other forms. One of these forms, known as hot-dry rock has attracted some attention in the volcanic areas of the White Mountains, east of Phoenix. In such resource areas, heat is available, but there is insufficient water to conduct the heat to the surface. In some of these cooler climes, geothermal heat pumps might be a sensible application. The Geothermal Heat Pump Consortium maintains a web site with more information.
In summary, major geothermal resources exist near but not in Arizona. The resource that exists in the state has been recognized and, to some degree, explored, but no sites are considered economically commercial at this time. For more information on geothermal power, visit: http://www.geothermal.org/links.html | <urn:uuid:77733d86-766e-4eb4-b268-2870a26bd1cf> | 3.546875 | 625 | Knowledge Article | Science & Tech. | 30.85 | 95,524,289 |
MR. We've all seen those creaky old windmills on farms, and although they may seem about as lowtech as you can get, those old windmills are the predecessors for new modern wind turbines that generate electricity. The same wind that used to pump water for cattle is now turning giant wind turbines to power cities and homes. OK, have a look at this wind farm in the California desert, a hot desert next to tall mountains an ideal place for a lot of wind. Here's another one on the windy prairies of Wyoming.
Now, today's wind turbines are much more complicated machines than the old prairie windmills, but the principle is the same. Both capture the wind's energy. OK, here's how it works. First, a wind turbine blade works sort of like an airplane wing. Blowing air passes around both sides of the blade. The shape of the blade causes the air pressure to be uneven higher on one side of the blade and lower on the other and that's what makes it spin. The uneven pressure causes the blades to spin around the center.
Of the turbine. On the top, there's a weather vane that's connected to a computer to keep the turbine turned into the wind so it captures the most energy. Now, the blades are attached to a shaft which only turns about 18 revolutions a minute, and that's not nearly fast enough to generate electricity by itself. So the rotor shaft spins a series of gears that increase the rotation up to about 1,800 revolutions per minute. And at that speed, a generator can produce a lot of electricity. So why are wind turbines so tall Well, the higher up you go, the windier it is more.
Our lab in Darwin
Music playing Anna Richards Hi, my name's Anna Richards. I'm a soil and carbon ecologist with CSIRO Ecosystem Sciences in Darwin. Our lab is the only CSIRO lab in northwestern Australia. For more than 40 years we've been carrying out environmental and agricultural research in the Top End. This beautiful site is home to Ecosystem Sciences and the Darwin Science Education Centre. About 30 staff, students and industrial trainees are currently based in Darwin. We also share our site with the N.T Government's Flora and Fauna Division, the Parks and Wildlife Commission's Wildlife Management Group,.
And the Tiwi Land Council. So what do we do up here Well, our mission is to conduct integrated ecological and socioeconomic research to underpin sustainable land management and regional development in the north. Our research focuses on four major areas Firstly, Savanna burning. This work looks at the full range of biophysical and socioeconomic issues relating to savanna fire management for biodiversity conservation and Greenhouse gas abatement, especially on Aboriginal lands. Our fire research underpinned one of the first methodologies approved under the Carbon Farming Initiative to reduce greenhouse gas emissions in northern Australia.
Secondly, Indigenous natural resource management. CSIRO staff member talking with an Aboriginal woman CSIRO has strong and productive partnerships with Aboriginal communities right across the Top End. This work includes fire management, invasive species management, aquatic resource conservation, biodiversity monitoring, and marine planning. The development of a suite of calendars of Indigenous seasonal knowledge with six language groups across the north has been a recent highlight. Thirdly, Invertebrate biodiversity. The Darwin lab has internationally leading expertise in ants, the world's dominant faunal group in terms of biomass and energy flow. We hold the world's most extensive collection of Australian ants,.
With nearly 6,000 species! This collection supports most of the ecological work done on ants in Australia. We've has also been working on the ecology and management of pest ants, such as the Yellow Crazy ant in Arnhem Land, for more than ten years. Our ant biodiversity lab is also home to many of our students. About 20 international students, mostly from France, spend three to six months staying with us onsite and working on a range of projects. They make a vital contribution to our research capability. Finally, Rangeland ecology.
Rangelands cover about 85 of the continent. Pastoralism is the main land use but there's increasing interest in new economic opportunities, such as carbon sequestration. We're also exploring opportunities for the development of the northern beef industry to improve productivity and profitability. We're lucky to have one of the largest and best preserved areas of remnant tropical savanna woodland in the Darwin suburbs. Our ten hectare patch of bush has been the focus of more than 40 collaborative research projects in the last 16 years. So that's it from me.
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How Home Solar Power System Works.Visit.diygreenenergyguidesearth4energydiysolarpanels Or, Watch watchv8e4jeMapnKs This tutorial demonstrate.. | <urn:uuid:3bcc2deb-027d-4d50-b6aa-58cd6ef6cdde> | 3.296875 | 1,546 | Content Listing | Science & Tech. | 45.162307 | 95,524,325 |
"We've been studying the Sun for decades, and now we're finally going to go where the action is," said Alex Young, associate director for science.
Unlike conventional solar cells used for generating electricity on land, these cells are highly sophisticated and efficient.
The Indian space agency will have a busy year-end with several rocket launches planned from its rocket port at Sriharikota in Andhra Pradesh.
Washington, July 23 (IANS) US space agency NASA is preparing to launch a probe in August to study the Sun closer than any human-made object ever has, revealing multiple mysteries behind the star.
Buzz Aldrin, along with Neil Armstrong and Michael Collins, was part of the Apollo 11 mission which landed the first two humans on the moon on July 20, 1969.
Washington, July 21 (IANS) The parachutes for NASA's next crew vehicle, the Orion capsule, intended to carry humans to deep space, has successfully passed a drop test, the US space agency said.
Washington, July 21 (IANS) NASA is yet to make contact with its Mars Opportunity rover ever since a massive storm started on the Red Planet in June.
Washington, July 21 (IANS) The personal collection of US astronaut Neil Armstrong, the first man to set foot on the Moon 49 years ago on July 20, will be auctioned by his family.
Washington, July 20 (IANS) NASA has launched an online toolkit to make it easier for users to find, analyse and utilise the most relevant satellite data for their research, business projects or conservation efforts.
Washington, July 19 (IANS) Observations from NASA's Chandra X-ray Observatory indicates that scientists may have for the first time seen a young star devouring a young planet or planets.
London, July 18 (IANS) Geologists have classified the last 4,200 years as being a distinct Earth age and are calling it a new chapter -- the "Meghalayan Age" -- the onset of which was marked by a mega-drought that crushed a number of civilizations worldwide.
The sale and purchase of drones in currently restricted by the Director General of Civil Aviation (DGCA) in India.
London, July 18 (IANS) Geologists have classified the last 4,200 years as being a distinct Earth age and are calling it a new chapter -- the "Meghalayan Age" -- the onset of which was marked by a mega-drought that crushed a number of civilisations worldwide.
London, July 17 (IANS) The origins of ceramic production can be traced to Japan and closely linked with intensified fishing at the end of the last Ice Age, finds a study, shedding light on how prehistoric hunter-gatherers processed and consumed foods over this period.
New Delhi, July 17 (IANS) Google on Tuesday dedicated an animated Doodle to Belgian cosmologist Georges Lemaitre who in 1927 propounded the Big Bang theory when he theorised that the universe began as a single point and expanded to become as big as it is now.
Washington, July 17 (IANS) Scientists have found that the oldest direct evidence of bread found to date is at least 4,000 years before the advent of agriculture, according to a new study. | <urn:uuid:f6da003f-7833-4474-bb60-dbc9c4e2a0a8> | 3.03125 | 669 | Content Listing | Science & Tech. | 35.637866 | 95,524,341 |
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slowmoVideo is an OpenSource program that creates slow-motion videos from your footage.
But it does not simply make your videos play at 0.01× speed. You can smoothly slow down and speed up your footage, optionally with motion blur.
How does slow motion work? slowmoVideo tries to find out where pixels move in the video (this information is called Optical Flow), and then uses this information to calculate the additional frames between the ones recorded by your camera.
- Videos in any format supported by ffmpeg can be loaded. Image sequences can also be loaded, so, if you did a timelapse with too few frames, slowmoVideo may help as well.
- slowmoVideo does not work with a constant slowdown factor but with curves that allow arbitrary time accelereation/deceleration/reversal.
- Motion blur can be added, as much as you want.
The most recent changes to slowmoVideo can be read in the changelog.
These parts are used by slowmoVideo:
- Qt4/Qt5 as C++ programming framework
- GPU-KLT+FLOW and OpenCV for calculating the optical flow
- ffmpeg for reading and writing video files | <urn:uuid:a1096471-0a01-44b3-a172-01b26a2c9f2a> | 2.6875 | 294 | Knowledge Article | Software Dev. | 47.669643 | 95,524,367 |
New antimatter method to provide ‘a major experimental advantage’
Researchers have proposed a method for cooling trapped antihydrogen which they believe could provide ‘a major experimental advantage’ and help to map the mysterious properties of antimatter that have to date remained elusive.
The new method, developed by a group of researchers from the USA and Canada, could potentially cool trapped antihydrogen atoms to temperatures 25 times colder than already achieved, making them much more stable and a lot easier to experiment on.
The suggested method, which has been published today, 7 January 2013, in IOP Publishing’s Journal of Physics B: Atomic, Molecular and Optical Physics, involves a laser which is directed at antihydrogen atoms to give them a ‘kick’, causing them to lose energy and cool down.
Antihydrogen atoms are formed in an ultra-high vacuum trap by injecting antiprotons into positron plasma. An atomic process causes the antiproton to capture a positron which gives an electronically excited antihydrogen atom.
Typically, the antihydrogen atoms have a lot of energy compared to the trapping depth which can distort the measurements of their properties. As it is only possible to trap very few antihydrogen atoms, the main method for reducing the high energies is to laser cool the atoms to extremely low temperatures.
Co-author of the study, Professor Francis Robicheaux of Auburn University in the USA, said: “By reducing the antihydrogen energy, it should be possible to perform more precise measurements of all of its parameters. Our proposed method could reduce the average energy of trapped antihydrogen by a factor of more than 10.
“The ultimate goal of antihydrogen experiments is to compare its properties to those of hydrogen. Colder antihydrogen will be an important step for achieving this.”
This process, known as Doppler cooling, is an established method for cooling atoms; however, because of the restricted parameters that are needed to trap antimatter, the researchers need to be absolutely sure that it is possible.
“It is not trivial to make the necessary amount of laser light at a specific wavelength of 121 nm. Even after making the light, it will be difficult to mesh it with an antihydrogen trapping experiment. By doing the calculations, we’ve shown that this effort is worthwhile,” continued Professor Robicheaux.
Through a series of computer simulations, they showed that antihydrogen atoms could be cooled to around 20 millikelvin; trapped antihydrogen atoms so far have energies up to 500 millikelvin.
In 2011, researchers from CERN reported that they had trapped antimatter for over 1000 seconds – a record. A year later, the first experiments were performed on antihydrogen whilst it was trapped between a series of magnets.
Even though the processes that control the trapping are largely unknown, the researchers believe that the laser cooling should increase the amount of time antihydrogen can be trapped for.
“Whatever the processes are, having slower moving, and more deeply trapped, antihydrogen should decrease the loss rate,” said Professor Robicheaux.
Colder antihydrogen atoms could also be used to measure the gravitational property of antimatter. “No one has ever seen antimatter actually fall in the field of gravity,” said co-author Dr Makoto Fujiwara of TRIUMF, Canada’s National Laboratory for Particle and Nuclear Physics. “Laser cooling would be a very significant step towards such an observation.” | <urn:uuid:c3fa935c-d99e-457b-a1e6-26d3e5a4f9e2> | 3.484375 | 735 | News Article | Science & Tech. | 21.596925 | 95,524,389 |
Family Cordulegastridae Tillyard, 1917
For an introduction to this family, please refer to: Dijkstra, K.-D.B. & R. Lewington, 2006. Field guide to the Dragonflies of Britain and Europe. British Wildlife Publishing. 1-320.
Easily recognised by the very large size (7-10 cm), the black-and-yellow body pattern and the eyes meeting above only narrowly. Males possess an anal triangle in the Hw and auricles on the sides of S2. Females have a unique vulvar scale that serves as an ovipositor, projecting well beyond the tip of the abdomen. It is used to deposit the eggs in the bottom substrate of springs and small brooks, where goldenrings are often the only species of dragonfly present. Aeshnids are often large and have similar appearance and venation, but the eyes are broadly confluent. Some gomphids also have a black-and-yellow coloration, but are smaller and the eyes are widely separated above. [Adapted from Dijkstra & Lewington 2006]
Map citation: Clausnitzer, V., K.-D.B. Dijkstra, R. Koch, J.-P. Boudot, W.R.T. Darwall, J. Kipping, B. Samraoui, M.J. Samways, J.P. Simaika & F. Suhling, 2012. Focus on African Freshwaters: hotspots of dragonfly diversity and conservation concern. Frontiers in Ecology and the Environment 10: 129-134.
Citation: Dijkstra, K.-D.B (editor). African Dragonflies and Damselflies Online. http://addo.adu.org.za/ [2018-07-18]. | <urn:uuid:393b6e6d-ada2-4e57-9225-afa9634b8d6c> | 3.578125 | 379 | Knowledge Article | Science & Tech. | 67.73528 | 95,524,394 |
An investigation was made of the variation of the pressure limits of flame propagation with tube diameter for quiescent propane with tube diameter for quiescent propane-air mixtures. Pressure limits were measured in glass tubes of six different inside diameters, with a precise apparatus. Critical diameters for flame propagation were calculated and the effect of pressure was determined. The critical diameters depended on the pressure to the -0.97 power for stoichiometric mixtures. The pressure dependence decreased with decreasing propane concentration. Critical diameters were related to quenching distance, flame speeds, and minimum ignition energy. | <urn:uuid:a470fdd0-ff7b-4d78-a475-d680241c7f5a> | 2.53125 | 123 | Truncated | Science & Tech. | 12.305 | 95,524,395 |
"This is how galaxies grow. You can see the smaller galaxy coming in and getting shredded, eventually leaving its stars scattered through the halo of the host galaxy," said Aaron Romanowsky, a research astronomer at the University of California, Santa Cruz, and coauthor of a paper on the discovery that has been accepted for publication in Astrophysical Journal Letters and is available online at arxiv.org. The study was carried out by an international team of astronomers led by David Martínez-Delgado of the Max Planck Institute for Astronomy in Heidelberg.
According to modern cosmological theory, large galaxies were built up from smaller progenitors through a hierarchical process of mergers. Astronomers can see many examples of mergers involving massive galaxies, but mergers of two dwarf galaxies have been hard to find. "We should see the same things at smaller scales, with small galaxies eating smaller ones and so on," Romanowsky said. "Now we have this beautiful image of a dwarf galaxy consuming a smaller dwarf."
NGC 4449 is located 12.5 million light-years from Earth and is a member of a group of galaxies in the constellation Canes Venatici. In size and morphology, it is very similar to one of the Milky Way's satellite galaxies, the Large Magellanic Cloud.
The stellar stream in NGC 4449 was first detected by another group of astronomers as a mysterious, faint smudge in digitized photographic plates from the Digitized Sky Survey project, and it is also visible in archival images from the Sloan Digital Sky Survey. But if it had been just a bit fainter, more diffuse, or farther from the host galaxy, it could easily have been missed. The authors of the new study called it a "stealth merger," where an infalling satellite galaxy is nearly undetectable by conventional means, yet has a substantial influence on its host galaxy.
Martínez-Delgado organized a campaign to follow up on the initial report with more detailed observations. R. Jay GaBany, a Bay Area amateur astronomer and astrophotographer with whom Martínez-Delgado has frequently collaborated, obtained exceptionally deep, wide-field images of NGC 4449 with the half-meter Black Bird Observatory telescope (located in the Sierra Nevada mountains). Those images confirmed the presence of a faint substructure in the halo of the galaxy. Romanowsky, along with UCSC graduate student Jacob Arnold, then used the 8.2-meter Subaru Telescope in Hawaii to obtain high-resolution images in which the individual stars in the stellar stream can be seen.
"I don't think I'd ever seen a picture of a galaxy merger where you can see the individual stars," Romanowsky said. "It's really an impressive image."
In addition to Martínez-Delgado, Romanowsky, Arnold, and GaBany, the coauthors of the Astrophysical Journal Letters paper include Jean Brody, professor of astronomy and astrophysics at UC Santa Cruz; Francesca Annibali at the Astronomical Observatory of Bologna; Jurgen Fliri at the Observatory of Paris; Stefano Zibetti at the University of Copenhagen; Roeland van der Marel and Alessandra Aloisi at the Space Telescope Science Institute; Hans-Walter Rix and Andrea Maccio at the Max Planck Institute; Taylor Chonis at the University of Texas, Austin; Julio Carballo-Bello at the Canary Astrophysics Institute; J. Gallego-Laborda at Fosca Nit Observatory in Spain; and Michael Merrifield at the University of Nottingham, England.
This research was supported by the National Science Foundation, NASA, and the UCSC-UARC Aligned Research Program.
Tim Stephens | EurekAlert!
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
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 | Materials Sciences
20.07.2018 | Physics and Astronomy
20.07.2018 | Materials Sciences | <urn:uuid:9383f0d9-fb93-4ff9-bde0-ca1551404371> | 3.546875 | 1,361 | Content Listing | Science & Tech. | 35.329943 | 95,524,418 |
Dendritic Computation of Direction in Retinal Neurons
The retina utilizes a variety of dendritic mechanisms to compute direction from image motion. The computation is accomplished by starburst amacrine cells (SBACs) which are GABAergic neurons presynaptic to direction-selective ganglion cells (DSGCs). SBACs are symmetric neurons with several branched dendrites radiating out from the soma. Larger EPSPs are produced in the dendritic tips of SBACs as a stimulus sequentially activates inputs from the base of each dendrite outwards. The directional difference in EPSP amplitude is further amplified near the dendritic tips by voltage-gated channels to produce directional release of GABA. Reciprocal inhibition between adjacent SBACs may also amplify directional release. Directional signals in the independent SBAC branches are preserved because each dendrite makes selective contacts only with DSGCs of the appropriate preferred-direction. Directional signals are further enhanced within the dendritic arbor of the DSGC, which essentially comprises an array of distinct dendritic compartments. Each of these dendritic compartments locally sum excitatory and inhibitory inputs, amplifies them with voltage-gated channels, and generates spikes that propagate to the axon via the soma. Overall, the computation of direction in the retina is performed by several local dendritic mechanisms both presynaptic and postsynaptic, with the result that directional responses are robust over a broad range of stimuli.
KeywordsPrefer Direction Bipolar Cell Directional Signal Dendritic Arbor Reciprocal Inhibition
Thanks to David Vaney for the image of the starburst amacrine cell in Fig. 13.1a. This study was supported by NEI grant EY022070.
- Masland RH (2012) The neuronal organization of the retina. Neuron 76:266–280Google Scholar
- Rall W (1964) Theoretical significance of dendritic trees for neuronal input-output relations. In: Reis RF (ed) Neural theory and modeling. Stanford University Press, Stanford, CA, pp 72–97Google Scholar
- Rodieck RW (1998) The first steps in seeing. Sinauer Associates, Sunderland, MA. ISBN 9780878937578Google Scholar
- Schachter MJ, Oesch N, Smith RG, Taylor WR (2010) Dendritic spikes amplify the synaptic signal to enhance detection of motion in a simulation of the direction-selective ganglion cell. PLoS Comput Biol 6(8):e1000899Google Scholar
- Vaney DI, Sivyer B, Taylor WR (2012) Direction selectivity in the retina: symmetry and asymmetry in structure and function. Nat Rev Neurosci 13:194–208Google Scholar
- Vigeland LE, Contreras D, Palmer LA (2013) Synaptic mechanisms of temporal diversity in the lateral geniculate nucleus of the thalamus. J Neurosci 33:1887–1896Google Scholar | <urn:uuid:50ed9058-1658-4bd4-a445-25ef2c0c6e9d> | 2.53125 | 633 | Academic Writing | Science & Tech. | 25.346818 | 95,524,456 |
Nowhere on earth the drama of abrupt climate change is coming to a head as in the Arctic.
It is obvious, that this drama has an impact on the whole planet. But in the public media it is ignored largely. Therefor I have begun some month ago to bring up this painful subject and I have published some podcast episodes and blog articles. This is a kind of condensed summary of this work.
A very important foundation we find in the publications of Natalia Shakhova and Igor Simeletov.
1. Breeze and Shakhova
Nick Breeze has conducted an extraordinary interview with Dr. Natalia Shakhova and Dr. Igor Semiletov.
Methane in the Arctic Shelf
There is a big reservoir of Methane stored in the East Siberian Arctic Shelf (ESAS).
Shakhova and Semiletov currently estimate that of the 2,000,000 sq km’s that comprise the ESAS, 200,000 sq km’s (10%) are what they would call hotspots, areas where methane emissions are observed as being far greater than in the lower background area.
Dr. Semiletov added that the 5 billion tonnes of methane that is currently in the Earth’s atmosphere represents about one percent of the frozen methane hydrate store in the East Siberian Arctic Shelf.
Cheers, the champagne bottle is open
The methane bottle is uncorked. There is a layer of permafrost in the subsea sediments, that hinders methane to be released since up to one million years.
We use an analogy where we compare the East Siberian Arctic Shelf to a bottle of champagne. So the gas produces within this bottle and it keeps accumulating as long as the cork serves as an impermeable lid. This lid is subsea permafrost. Before it was just permafrost [on land] but after it was submerged it became subsea permafrost and served to preserve an increasing amount of gas produced from its release to the ocean and atmosphere above. While this lid is impermeable, there is nothing to worry about. But when this lid loses its integrity, this is when we start worrying.
No way to stop
Once the bottle of methane deposits of the subsea sediments is uncorked, there is no way to stop this process, that began „thousands of years ago“.
Emissions that are occurring right now are the result of a combined effect of natural and anthropogenic warming and they will be accelerated until warming is turned to cooling. Even after it happens, there is no mechanism to stop permafrost disintegration in the ESAS besides shelf exposure above the sea level that would serve to freeze the gas migration paths so that they integrate with the permafrost.
2. FTE21 ~ Arctic Sea Ice Volume
The Arctic Sea Ice Volume is 2017 at it’s ever recorded low. Maybe this sounds somehow special, but what‘s going on in the Arctic now has huge consequences for the climate of the planet.
Finland‘s President Niinistö said in North Russia:
If We Lose the Arctic, We Lose the World
Torstein Viddal about the dire situation we are in:
Emotionally I think I will always be like – keeping it real. Accepting the situation we are in, is so much easier than denying it, because I suspect, that even the deniers fear what’s inside that box, but they are not looking into.
I have inserted a short introduction from THE Arctic expert in the world, Professor Peter Wadhams, from October 2016.
3. Multi Year Ice
Video from Peter Wadhams:
- 40 years ago nearly all ice in the Arctic was multi-year
- ice was heavy, it was really formidable stuff
- that’s gone
- the one year ice is much thinner, much weaker, much more mobile, it’s a different substance
Paul Beckwith explains in this video of Sept. 2016 how the next storm could push the rest of crushed ice out of the Arctic.
Arctic Sea Ice has been pulverized, hacked to pieces, smashed to smithereens; you can use whatever phrase you want. With a week or two left in the 2016 melt season, and another storm in the long range forecast, all bets are off.
4. FTE23 ~ Methane Monster 3.0
“… pingos, which were formed by local accumulation of hydrate (ice) below the sediment surface in the past, and by methane migrating upwards through conduits. Pingos and similar structures can link to deep-rooted plumbing systems that allow thermogenic fluid migration from several-kilometers-deep sedimentary basins.
Paull et al. describe pingo-like-features on the Beaufort Sea Shelf, adding that a thermal pulse of more than 10 degrees Celsius is still propagating down into the submerged sediment and may be decomposing gas hydrate as well as permafrost.“
The Keeeling Curve
5. FTE24 Arctic ~ Sam Carana about the Arctic and global temperature
And here comes an exclusive interview with Sam Carana!
In my view Sam Carana is one of the leading scientists, who is engaged in the topic of abrupt climate change. But nobody knows who is behind this name, he prefers to remain anonymous.
In this episode of the FasterThanExpected podcast we focus on the question: How is ice melting in the Arctic and methane influencing the global temperature?
+10 C by 2021?
Sam Carana sums up some influences on the global temperature:
In summary, adding up all the warming associated with the above elements results in a total potential global temperature rise (land and ocean) of more than 10°C or 18°F in a matter of years, by as early as 2021, assuming that no geoengineering will take place over the next few years.
6. Guy McPherson: Biology for Doomers
Guy McPherson, with his major fields conservation and evolutionary biology, is the only biologist, I know, who assumes that these changes lead to a mass extinction, even of the human species, within a very short period of time, within a few years.
Guy McPherson, Faster than Expected, 9-Feb-2017:
As I’ve pointed out previously, I doubt there will be a human on Earth by mid-2026. Indeed, I doubt there will be complex life on this planet by then. It’ll be a small world, as was the case in the wake of each of the five prior Mass Extinction events on Earth. Bacteria, fungi, and microbes will dominate.
Habitat, habitat, habitat!
As I’ve pointed out repeatedly, humans will lose habitat on Earth before the last human dies. The final human probably will die after running out of canned food in a bunker. And he or she will not know human extinction has occurred.
Some people are preparing for the collapse of civilization. I used to be one of them. Now I spend my days living, rather than pursuing dying more slowly than expected. … Pressum diem (squeeze the day). Make every one matter. Like all of us, the days are going away faster than expected.
7) Kevin Hester and Dahr Jamail about the ongoing climate disruption
This is the kind of summary, I have been waiting for. Kevin Hester is discussing with Dahr Jamail a wide range of subjects around the ongoing climate crisis, including the idiocy of building Nuclear plants on coastlines being battered by rising sea levels and ever stronger storms …
Listen to a great Nature Bats Last radio show from 8-Mar-2018:
Is there anything to add?
11801total visits,3visits today | <urn:uuid:2c85b7d5-9f49-4d74-b09c-0b12ee770379> | 2.875 | 1,633 | Personal Blog | Science & Tech. | 51.856001 | 95,524,460 |
Often we need to debug a code which involves some interacting program entities. Imagine a state machine which, depending on certain conditions goes into different states and the order of transitions between states is important.
One obvious solution is to output debug messages to the console which usually goes along with some tedious analysis and often drawing diagrams on a paper. Thus making a clear picture of what’s happening is quite difficult especially if the code being analyzed is constantly changing during development.
It would be convenient if such diagrams can be created automatically, without the need in interpretation of numerous debug messages. You can find a handful of tools capable to convert a sequence described as a plain text into a lovely sequence diagram. Normally in order to get a full-blown UML sequence diagram you will need to use a fairly complex syntax. But for the purposes of understanding and debugging your code in most cases you will need to follow only a few simple rules.
I like the syntax that is used on the site http://bramp.github.io/js-sequence-diagrams. Here is an example taken from its home page:
Title: Here is a title
A-> B: Normal line
B -> C: Dashed line
C->> D: Open arrow
D – >> A: Dashed open arrow
Copy and paste the text above into the form on the web site and you’ll get a nicely looking sequence diagram:
Much clearer, isn’t it? | <urn:uuid:0182735e-42a5-4296-a8ad-7d4f94b811ef> | 2.875 | 299 | Personal Blog | Software Dev. | 45.427814 | 95,524,477 |
Schoof's algorithm is an efficient algorithm to count points on elliptic curves over finite fields. The algorithm has applications in elliptic curve cryptography where it is important to know the number of points to judge the difficulty of solving the discrete logarithm problem in the group of points on an elliptic curve.
The algorithm was published by René Schoof in 1985 and it was a theoretical breakthrough, as it was the first deterministic polynomial time algorithm for counting points on elliptic curves. Before Schoof's algorithm, approaches to counting points on elliptic curves such as the naive and baby-step giant-step algorithms were, for the most part, tedious and had an exponential running time.
This article explains Schoof's approach, laying emphasis on the mathematical ideas underlying the structure of the algorithm.
Let be an elliptic curve defined over the finite field , where for a prime and an integer . Over a field of characteristic an elliptic curve can be given by a (short) Weierstrass equation
with . The set of points defined over consists of the solutions satisfying the curve equation and a point at infinity . Using the group law on elliptic curves restricted to this set one can see that this set forms an abelian group, with acting as the zero element.
In order to count points on an elliptic curve, we compute the cardinality of .
Schoof's approach to computing the cardinality makes use of Hasse's theorem on elliptic curves along with the Chinese remainder theorem and division polynomials.
Hasse's theorem states that if is an elliptic curve over the finite field , then satisfies
This powerful result, given by Hasse in 1934, simplifies our problem by narrowing down to a finite (albeit large) set of possibilities. Defining to be , and making use of this result, we now have that computing the cardinality of modulo where , is sufficient for determining , and thus . While there is no efficient way to compute directly for general , it is possible to compute for a small prime, rather efficiently. We choose to be a set of distinct primes such that . Given for all , the Chinese remainder theorem allows us to compute .
In order to compute for a prime , we make use of the theory of the Frobenius endomorphism and division polynomials. Note that considering primes is no loss since we can always pick a bigger prime to take its place to ensure the product is big enough. In any case Schoof's algorithm is most frequently used in addressing the case since there are more efficient, so called adic algorithms for small-characteristic fields.
The Frobenius endomorphism
Given the elliptic curve defined over we consider points on over , the algebraic closure of ; i.e. we allow points with coordinates in . The Frobenius endomorphism of over extends to the elliptic curve by .
This map is the identity on and one can extend it to the point at infinity , making it a group morphism from to itself.
The Frobenius endomorphism satisfies a quadratic polynomial which is linked to the cardinality of by the following theorem:
Theorem: The Frobenius endomorphism given by satisfies the characteristic equation
Thus we have for all that , where + denotes addition on the elliptic curve and and
denote scalar multiplication of by and of by .
One could try to symbolically compute these points , and as functions in the coordinate ring of
and then search for a value of which satisfies the equation. However, the degrees get very large and this approach is impractical.
Schoof's idea was to carry out this computation restricted to points of order for various small primes .
Fixing an odd prime , we now move on to solving the problem of determining , defined as , for a given prime .
If a point is in the -torsion subgroup , then where is the unique integer such that and .
Note that and that for any integer we have . Thus will have the same order as . Thus for belonging to , we also have if . Hence we have reduced our problem to solving the equation
where and have integer values in .
Computation modulo primes
The lth division polynomial is such that its roots are precisely the x coordinates of points of order l. Thus, to restrict the computation of to the l-torsion points means computing these expressions as functions in the coordinate ring of E and modulo the lth division polynomial. I.e. we are working in . This means in particular that the degree of X and Y defined via is at most 1 in y and at most
The scalar multiplication can be done either by double-and-add methods or by using the th division polynomial. The latter approach gives:
where is the nth division polynomial. Note that
is a function in x only and denote it by .
We must split the problem into two cases: the case in which , and the case in which . Note that these equalities are checked modulo .
Case 1:
By using the addition formula for the group we obtain:
Note that this computation fails in case the assumption of inequality was wrong.
We are now able to use the x-coordinate to narrow down the choice of to two possibilities, namely the positive and negative case. Using the y-coordinate one later determines which of the two cases holds.
We first show that X is a function in x alone. Consider .
Since is even, by replacing by , we rewrite the expression as
and have that
Here, it seems not right, we throw away ?
Now if for one then satisfies
for all l-torsion points P.
As mentioned earlier, using Y and we are now able to determine which of the two values of ( or ) works. This gives the value of . Schoof's algorithm stores the values of in a variable for each prime l considered.
Case 2:
We begin with the assumption that . Since l is an odd prime it cannot be that and thus . The characteristic equation yields that . And consequently that .
This implies that q is a square modulo l. Let . Compute in and check whether . If so, is depending on the y-coordinate.
If q turns out not to be a square modulo l or if the equation does not hold for any of w and , our assumption that is false, thus . The characteristic equation gives .
Additional case
If you recall, our initial considerations omit the case of .
Since we assume q to be odd, and in particular, if and only if has an element of order 2. By definition of addition in the group, any element of order 2 must be of the form . Thus if and only if the polynomial has a root in , if and only if .
1. An elliptic curve .
2. An integer q for a finite field with .
The number of points of E over .
Choose a set of odd primes S not containing p such that
Put if , else .
Compute the division polynomial .
All computations in the loop below are performed in the ring
Let be the unique integer such that and .
Compute , and .
else if q is a square modulo l then
compute w with
else if then
Use the Chinese Remainder Theorem to compute t modulo N
from the equations , where .
Most of the computation is taken by the evaluation of and , for each prime , that is computing , , , for each prime . This involves exponentiation in the ring and requires multiplications. Since the degree of is , each element in the ring is a polynomial of degree . By the prime number theorem, there are around primes of size , giving that is and we obtain that . Thus each multiplication in the ring requires multiplications in which in turn requires bit operations. In total, the number of bit operations for each prime is . Given that this computation needs to be carried out for each of the primes, the total complexity of Schoof's algorithm turns out to be . Using fast polynomial and integer arithmetic reduces this to .
Improvements to Schoof's algorithm
In the 1990s, Noam Elkies, followed by A. O. L. Atkin, devised improvements to Schoof's basic algorithm by restricting the set of primes considered before to primes of a certain kind. These came to be called Elkies primes and Atkin primes respectively. A prime is called an Elkies prime if the characteristic equation: splits over , while an Atkin prime is a prime that is not an Elkies prime. Atkin showed how to combine information obtained from the Atkin primes with the information obtained from Elkies primes to produce an efficient algorithm, which came to be known as the Schoof–Elkies–Atkin algorithm. The first problem to address is to determine whether a given prime is Elkies or Atkin. In order to do so, we make use of modular polynomials, which come from the study of modular forms and an interpretation of elliptic curves over the complex numbers as lattices. Once we have determined which case we are in, instead of using division polynomials, we are able to work with a polynomial that has lower degree than the corresponding division polynomial: rather than . For efficient implementation, probabilistic root-finding algorithms are used, which makes this a Las Vegas algorithm rather than a deterministic algorithm.
Under the heuristic assumption that approximately half of the primes up to an bound are Elkies primes, this yields an algorithm that is more efficient than Schoof's, with an expected running time of using naive arithmetic, and using fast arithmetic. Although this heuristic assumption is known to hold for most elliptic curves, it is not known to hold in every case, even under the GRH.
Several algorithms were implemented in C++ by Mike Scott and are available with source code. The implementations are free (no terms, no conditions), and make use of the MIRACL library which is distributed under the AGPLv3.
- Schoof's algorithm implementation for with prime .
- Schoof's algorithm implementation for .
- R. Schoof: Elliptic Curves over Finite Fields and the Computation of Square Roots mod p. Math. Comp., 44(170):483–494, 1985. Available at http://www.mat.uniroma2.it/~schoof/ctpts.pdf
- R. Schoof: Counting Points on Elliptic Curves over Finite Fields. J. Theor. Nombres Bordeaux 7:219–254, 1995. Available at http://www.mat.uniroma2.it/~schoof/ctg.pdf
- G. Musiker: Schoof's Algorithm for Counting Points on . Available at http://www.math.umn.edu/~musiker/schoof.pdf
- V. Müller : Die Berechnung der Punktanzahl von elliptischen kurven über endlichen Primkörpern. Master's Thesis. Universität des Saarlandes, Saarbrücken, 1991. Available at http://lecturer.ukdw.ac.id/vmueller/publications.php
- A. Enge: Elliptic Curves and their Applications to Cryptography: An Introduction. Kluwer Academic Publishers, Dordrecht, 1999.
- L. C. Washington: Elliptic Curves: Number Theory and Cryptography. Chapman & Hall/CRC, New York, 2003.
- N. Koblitz: A Course in Number Theory and Cryptography, Graduate Texts in Math. No. 114, Springer-Verlag, 1987. Second edition, 1994 | <urn:uuid:e407c099-0901-46a4-bdfa-6314418de9c2> | 3.328125 | 2,493 | Knowledge Article | Science & Tech. | 54.61526 | 95,524,484 |
Feature-oriented software architecture is a way of organizing code around the features that the program provides instead of the program's objects and components. In the development of a feature-oriented software system, the developers, supplied with a set of features, select and organize features to construct the desired system. This approach, by better aligning the implementation of a system with the external view of users, is believed to have many potential benefits such as feature reuse and easy maintenance. However, there are challenges in the formal verification of feature-oriented systems: first, the product may grow very large and complicated. As a result, it's intractable to apply the traditional formal verification techniques such as model checking on such systems directly; second, since the number of feature-oriented products the developers can build is exponential in the number of features available, there may be redundant verification work if doing verification on each product. For example, developers may have shared specifications on different products built from the same set of features and hence doing verification on these features many times is really unnecessary. All these drive the need for modular verifications for feature-oriented architectures. Assume-guarantee reasoning as a modular verification technique is believed to be an effective solution. In this thesis, I compare two verification methods of this category on feature-oriented systems and analyze the results. Based on their pros and cons, I propose a new modular model checking method to accomplish verification for sequential feature compositions with cyclic connections between the features. This method first builds an abstract finite state machine, which summarizes the information related to checking the property/specification from the concrete feature design, and then applies a revised CTL model checker to decide whether the system design can preserve the property or not. Proofs of the soundness of my method are also given in this thesis.
Worcester Polytechnic Institute
All authors have granted to WPI a nonexclusive royalty-free license to distribute copies of the work. Copyright is held by the author or authors, with all rights reserved, unless otherwise noted. If you have any questions, please contact firstname.lastname@example.org.
Wang, Xiaoning, "A Modular Model Checking Algorithm for Cyclic Feature Compositions" (2005). Masters Theses (All Theses, All Years). 64.
modular verification, model checking, assume-guarantee reasoning, feature-oriented software development, verification, Computer software, Design, Algorithms, Computer architecture, Feature-oriented programming (Computer science) | <urn:uuid:961d39ab-1780-4ed6-8e55-33e29187d638> | 2.640625 | 512 | Academic Writing | Software Dev. | 13.655888 | 95,524,497 |
Data of the „ROMAP“-Magentometer aids in reconstruction of flight path
Just a little time after Rosetta lander „Philae“ touched down on a comet it was clear that the mission was not continuing as expected, because the lander bounced off the surface. The international team of scientists lead by geophysicist Dr. Uli Auster from the Institut für Geophysik und extraterrestische Physik was working at the „Philae“ control center at that time and followed the incredible flight of the lander.
The data obtained by the ROMAP magnetometer from Braunschweig immediatly showed the signatures of this bouncing and the subsequent touchdowns. With the data, the movement on the comet can be reconstructed.
Bounce: two hours above the comet
In the evening of 12th November, 2014, the scientists around Dr. Hans-Ulrich Auster were surprised when they saw the data of the ROMAP magnetometer immediately after touchdown: „With the magnetometer we can reconstuct the movement of the lander, just like the rotation of a compass needle. Consequently we could see instantly that „Philae“ bounced off the surface and finally returned after two hours. After evaluating our data we now have more information on the path to the final and still unknown landing site“ explained Dr. Auster.
Possible collision with a crater rim
Now the magnetic field data reveals that after the first touchdown „Philae“ started to rotate about its vertical axis, says Auster. The reason was that the reaction wheel, that was stabilizing the lander during descend, transferred its momentum to the freely moving lander. Within 40 minutes Philae accelerated to a rotational velocity of about 5 rpm, which is comparable to a wind turbine at low wind speeds“ says the geophysicist. But after 45 minutes the pattern changed suddenly: „The rotational velocity decreased to half the original speed, the axis tilted and the lander began to tumble. Most likely the reason was a collision with a crater rim“ summarized Dr. Auster.
Second landing decides Philae's fate
The magnetometer from Braunschweig shows that the lander tumbled above the surface for another hour before it jarringly touched down for the second time. „Then the fate of the lander was decided, which was also visible in magnetic field signatures. After first grazing the surface, „Philae“ landed on its feet at the last moment. After another seven minute bounce the lander arrived at its final position surrounded by icy walls“ say Hans-Ulrich Auster. „Although there was some luck involved, the astonishing landing impressively demonstrated that the lander was sturdy enough to not only withstand the harsh environmental conditions of space but also managed to survive this arduous landing sequence.”
The Rosetta Lander Magnetometer and Plasma Monitor (ROMAP) is one of ten instruments on the lander „Philae“, that investigates the magnetic field and solar wind parameters of the comet 67P/Churyumov-Gerasimenko for the ESA Mission Rosetta. Lead by Dr. Hans-Ulrich Auster of the Institut für Geophysik und extraterrestrische Physik at Technische Universität Braunschweig scientists from the Energy Research center in Budapest, the Institut für Weltraumforschung Graz in Austria and the Max-Planck Institut für Sonnensystemforschung in Göttingen contribute.
Dr. Hans-Ulrich Auster
Institut für Geophysik und extraterrestrische Physik
Technische Universität Braunschweig
Tel.: 0531 391-5241
Stephan Nachtigall | idw - Informationsdienst Wissenschaft
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
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This site provides useful practical information related to global and national weather observing practices and instruments, including independent equipment reviews.
You will find much of the background in my book The Weather Observer’s Handbook (published by Cambridge University Press), details of which can also be found on this site, together with useful links and downloads.
Author, The Weather Observer’s Handbook
A nation obsessed with the weather? Yes, certainly, but which nation?
Tip of The Day
Barometric pressure is the easiest of all of the weather elements to measure, and even basic weather stations or household aneroid barometers can provide reasonably accurate readings. It is also the only weather element that can be observed indoors, making a barometer or barograph – analogue or digital – an ideal instrument for apartment dwellers.
All solar radiation instruments require an open exposure, one with as clear a horizon as possible: a flat rooftop or a mast are often suitable locations. The effects of obstructions can be assessed using a solar elevation diagram in conjunction with a site survey, although obstructions within about 3 degrees of the horizon have little effect on the record. The instruments must also be accurately levelled, and most also require some form of azimuth alignment and/or latitude setting. Never put yourself or others in danger when installing or maintaining meteorological instruments at height.
Most air temperature measurements are now made using resistance temperature devices (RTDs), which are steadily replacing liquid-in-glass thermometers. The main types of sensor in use today are the platinum resistance thermometer and the thermistor. The former is more accurate and more repeatable, but more expensive. Both can be made very small and thus highly responsive.
When choosing a weather station, or components of a weather station, decide firstly what the equipment will mainly be used for: some potential uses may not be immediately obvious. Once that is clear, review the relevant decision-making factors as outlined in The Weather Observer's Handbook, Chapter 2, then prioritize them against your requirements.
The preferred resolution of a recording raingauge is 0.1 or 0.2 mm; 1 mm tipping-bucket raingauges are too coarse for accurate measurements of small daily amounts. Recording raingauges should be logged at 1 minute or 5 minute resolution (higher frequencies are possible using an event-based logger). They should be regularly inspected for funnel blockage or any obstruction to the operating mechanism, which will result in the complete loss of useful record if not quickly corrected. | <urn:uuid:720b007b-5d61-4e78-b049-3724c7353c1d> | 2.90625 | 512 | Tutorial | Science & Tech. | 27.361727 | 95,524,536 |
Oxford Mathematician Karin Erdmann specializes in the areas of algebra known as representation theory (especially modular representation theory) and homological algebra (especially Hochschild cohomology). Here she discusses her latest work.
"Roughly speaking, representation theory investigates how algebraic systems can act on vector spaces. When the vector spaces are finite-dimensional this allows one to explicitly express the elements of the algebraic system by matrices, hence one can exploit linear algebra to study 'abstract' algebraic systems. In this way one can study symmetry, via group actions. One can also study irreversible processes. Algebras and their representations provide a natural frame for this.
An algebra is a ring which also is a vector space such that scalars commute with everything. An important construction are path algebras: Take a directed graph $Q$, which we call a quiver, and take a coefficient field $K$. Then the path algebra $KQ$ is the vector space over $K$ with basis all paths in $Q$. This becomes an algebra, where the product of two basis elements is either its concatenation if this exists, or is zero otherwise.
Algebras generalize groups, namely if we start with a group, we get naturally an algebra: take the vector space with basis labelled by the group, and extend the group multiplication to a ring structure.
When the coefficients are contained in the complex numbers, representations of groups have been studied for a long time, and have many applications. With coefficients in the integers modulo $2$, for example, the algebras and their representations are much harder to understand. For some groups, the representations have 'finite type'. These are well-understood but almost always they have 'infinite type'. With a few exceptional 'tame' cases, these are usually 'wild', that is there is no hope of a classification of the representations.
The same cases occur precisely for modulo 2 arithmetic and when the symmetry is based on dihedral or semidihedral or quaternion 2-groups. Dihedral 2-groups are symmetries of regular $n$-gons when $n$ is a power of 2. The smallest quaternion group is the famous one discovered by Hamilton.
Viewing these symmetries from groups in the wider context of algebras was used (a while ago) to classify such tame situations. Recently it was discovered that this is part of a much larger universe. Namely one can construct algebras from surface triangulations, in which the ones from the group setting occur as special cases.
One starts with a surface triangulation, and constructs from this a quiver, that is, a directed graph: Replace each edge of the triangulation by a vertex, and for each triangle
where in the last case $a=c\neq b$. At any boundary edge, draw a loop.
For example, consider triangulation of the torus with two triangles, as shown below. Then there are, up to labelling, two possible orientations of triangles and two possible quivers:
The tetrahedral triangulation of the sphere
gives rise to several quivers, depending on the oreintation of each traingle, for example:
The crystal in the north wing of the Andrew Wiles Building, home of Oxford Mathematics (image drawn above) can be viewed as a triangulation of a surface with boundary. We leave drawing the quiver to the reader.
Starting with the path algebra of such a quiver, we construct algebras by imposing explicit relations, which mimic the triangulation. Although the quiver can be arbitrarily large and complicated, there is an easy description of the algebras. We call these 'weighted surface algebras.' This is joint work with A. Skowronski.
We show that these algebras place group representations in a wider context. The starting point is that (with one exception) the cohomology of a weighted surface algebra is periodic of period four, which means that these algebras generalize group algebras with quaternion symmetry.
The relations which mimic triangles can be degenerated, so that the product of two arrows around a triangle become zero in the algebra. This gives rise to many new algebras. When all such relations are degenerated, the resulting algebras are very similar to group algebras with dihedral symmetry. If we degenerate relations around some but not all triangles, we obtain algebras which share properties of group algebras with semidihedral symmetry. Work on these is in progress." | <urn:uuid:89c54303-7a24-4c16-bfe7-25305c05bb55> | 2.609375 | 975 | Academic Writing | Science & Tech. | 34.617071 | 95,524,539 |
Global Warming: Cause and Mitigation
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Is our atmosphere being compromised from extreme utilization of diverse chemicals? This is the query that has been the position for foremost debate for several years, is human activities causing global warming? When debating in relation to global warming the prime thing to construe is what the foundation of global warming is, and the retort to this plain question is gases of greenhouse. Greenhouse gases are ordinary gases for instance Nitrous Oxide, CO2, or Methane and are produced in one modes or further ways. The preliminary way is, in the course of natural cycles, for illustration, CO2 is released in the course of plant process of photosynthesis or through animal respiration. The substitute greenhouse production of gas approaches from man’s employ of diverse products and fuels; this can direct to anthropogenic changes of climate.
Changes of Anthropogenic Climate are conversions in the atmosphere owing to the various activities carried out by humans, and there are realities that these sorts of changes are all over the world. By researching the size of the ice caps of polar we can formulate out that they are constricting and this could be owing to a warmer heat of atmosphere due to the anthropogenic changes in climate. An IPCC details from 2007 signifying levels of a few of the gases of greenhouse additionally exhibits that the greenhouse gases levels in the atmosphere of earth’s has been increasing ever since the time of post-industrial, this can purely be features to human made machines which has been on rising. Diverse behaviors of human being activities are contributing to the rise in temperature of earth.
Greenhouse gases are naturally occurring gasses that absorb heats which directly advanced by the sun rays and recoil of to the surface of earth; it’s not that these gases are atrocious in character, we in actuality depend on them to keep up our earth’s typical weather at a sustainable high temperature, which in matter of fact are purely constructive for our surroundings in moderation. The gases for illustration Carbon dioxide, Nitrous Oxide, and Methane in environment are expelled throughout means of inhalation, volcanic action, photosynthesis, and decomposition. They are in addition controlled by nature in succession to keep up these gases in safe restraint, for illustration, plants absorb carbon dioxide to run their cycles of force, this takes away from what is contemporary and composures the balances.
During the industrial revolution when human being started carrying out various activities of production they started burning variety of substances for illustration petroleum and coal which have rocketed carbon dioxide levels released through the process of burning and combustion. When carbon dioxide was discharge in atmosphere a little section of what is set free is reabsorbed by natural entity, the respite of it continues lingering in the air. In point of fact, as per to the EPA statements on CO2 found just about 85% of the entire emissions of human greenhouse gas, this can be massive confirmation to sustain that anthropogenic changes in climate are in point sourcing global warming.
The matter of global warming is just an inference, an idea, mostly unlock for debate, which is expressly spread out. As for my view on the topic, I expect global warming in point of fact is having an impact on our world. Acid rain is a good quality theme to glance at to uphold my belief, the rain pH levels possibly will not ever be an idyllic 7 owing to natural greenhouse gases, nevertheless they ought to not be at a level that would impair our atmosphere. The New York Times has constructed articles on how acid rain is influencing the Rockies and also national parks, I don’t perceive any additional source for this than a fast raise in pollutants. Other reasons for my worry are the apparent raise in force of tropical storms that have influenced our states and the news of so several tornadoes which can be source by friction of heat in the air. In view of the fact that we have released so much greenhouse gases into the atmosphere and sourced anthropogenic changes of climate, we have added to the heat that generates storms like these. I as well suppose in human advancement, consequently if we are going away to carry on moving forward like this, it is our accountability to place policies into play to conserve our welfare as well as our planets’.
A number of mitigations have been fetched forth to determine issues for instance melting polar ice caps and acid rain, all sourced by global warming. One of these policies is recognized as Coal taxing, coal taxing is the idea of adding up a tax to our natural resources that are regularly utilized by industries and companies. The sum of tax that is appended on to the fuel sale would all rely on how much fuel emission would add on to the atmosphere when utilized. This idea was proffered in hopes to acquire companies who are endeavoring to be cost cognizant to do one of two things, either decline their operation of these fuels, which successively decreases the releases that they create, or obtain them to discover additional options to acquire energy. One such substitute is the wind mills application to take advantage of wind power which is in actuality extra cost efficient and atmosphere friendly, as a result why wind power might be on the rise.
An additional possibility to restrict global warming is to control and capture carbon that is discharged into the air; this would more or less effort like when plant confines carbon for their cycles of energy. This idea might be effectual owing to the reality that it might considerably lesser levels of CO2 which are one of the utmost discharges in our atmosphere. On the other hand, it might be expensive to acquire the means and room to detain and store up the carbon. If I were to decide, I would state coal taxing appears the majority promising for two diverse reasons; not simply does this thought perhaps lesser our emissions, however it might as well motivate us to initiate into fresh forms of energy bringing on additional development for us in places we didn’t suppose to look, all the while being not as much of harmful to us.
Whether you suppose in global warming, or you estimate it’s a myth there is large quantity of engaging things to reckon when analyzing at this topic. Are anthropogenic climate changes excruciating our ecosystem? What might be the effect of these changes in climate? Or not even is or energy habit destructive to us, other than are they outdated, and must we initiate discovering additional advancements? All of these can construct the mind to doubt and might even fetch global warming.
- Anthropogenic Climate Change, retrieved from: http://www.global-greenhouse-warming.com/anthropogenic-climate-change.html
- Climate Change Indicators in the United States, [06.21.2013], retrieved from : http://www.epa.gov/climatechange/science/indicators/ghg/
- Overview of Greenhouse Gases, [06.21.2013], retrieved from: http://www.epa.gov/climatechange/ghgemissions/gases/co2.html
- Iver Peterson, [1985,] Acid Rain Starting to have an effect on Politics and Environment in West retrieved from : New York times press 30.03.1985
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0152 GMT July 23, 2018
But more importantly, they contain the mysterious dark matter, which accounts for 27 percent of all matter and energy, phys.org reported.
Current models of dark matter predict that galaxy clusters have very dense cores, and those cores contain a very massive galaxy that never moves from the cluster's center.
But after studying ten galaxy clusters, David Harvey at EPFL's Laboratory of Astrophysics and his colleagues in France and the UK have discovered that the density is much smaller than predicted, and that the galaxy at the center actually moves.
Every galaxy cluster contains a galaxy that is brighter than the others, aptly named "brightest cluster galaxy" or BCG.
Recent evidence from simulations of exotic, non-standard dark matter shows that BCGs actually wobble long after the galaxy cluster has relaxed. This is residual wobbling caused by massive merging of galaxy clusters.
The researchers compared their observations to the predictions from the BAHAMAS suite of cosmological hydro-dynamical simulations finding that the two did not match.
According to the Standard Model of dark matter (called ‘cold dark matter’), this wobbling doesn't exist because the enormous density of dark matter keeps it tightly bound at the center of the galaxy cluster.
Therefore, this mismatch suggests the existence of yet-unknown physics that have not been accounted for.
The galaxy clusters that the astronomers studied also act as strong gravitational lenses: they are so massive that they warp spacetime enough to distort light passing through them, like a lens.
As a result, they can be used to make a map of dark matter, working out where the center is and then observing how the BCG wobbles around this center.
"We found that the BCGs 'slosh' around at the bottom of the halos," said David Harvey. "This indicates that, instead of a dense region in the center of the galaxy cluster, there is a much shallower central density—a striking signal of exotic forms of dark matter right at the heart of galaxy clusters."
The wobbling also shows that BCGs cannot coincide exactly with the cluster's halo, meaning that certain models of galaxy clusters have to be adjusted.
The scientists will extend their research with larger surveys of galaxy clusters such as Euclid. They hope that this will allow them to confirm their findings, but to also determine if BCG wobbling originates in new fundamental physics or a novel astrophysical phenomenon. | <urn:uuid:6bf24508-aab5-428b-a91b-493185b6048e> | 3.65625 | 504 | News Article | Science & Tech. | 40.564681 | 95,524,573 |
Behaviour of trailing vortices in the vicinity of the ground
The aim of this experimental study is to analyze the mean velocity field and the turbulence occuring in the core of counter-rotating vortex pair in the vicinity of the ground. This experiment constitutes the second stage of a previous one the objective of which was to give a general view of a vortex pair close to the wall; it has been conducted in the THALES water tunnel fitted with a moving belt on the test section floor. In this way, the simulation of ground effect has been undertaken.
A three-dimensional component laser Doppler Anemometer has been used to measure the three components of the velocity and every component of the Reynolds stress tensor in an YOZ plane perpendicular to the direction of the flow.
Measurements in various crosswise planes have been made in sufficiently refined grids allowing a precise description of the vortex flow. The high density of data points obtained in this experiment makes possible the analysis of vorticity and associated circulation fields. It was observed that the axial vorticity was distributed into concentric paths at the first streamwise locations; farther downstream, a strong deformation of these iso-contour lines seems to be connected to the movement of the vortex centres when approaching the ground. Another main feature in the evolution of the vortex concerns the turbulence in the core; its constant level is notable whatever the measurement station in the streamwise direction considered. Values of k1/2/U0 as high as 15% indicates that a part of the velocity fluctuations comes probably from the wandering of the vortices. Information, as the orientation of the main shear stress axis in the core, have been gained by investigating contours plots of the joint probability density functions relating to transverse velocity fluctuations and their corresponding correlations. Laser sheet visualisations have been performed to identify the instabilities present in vortex core.
A calculation code which solves the Navier-Stokes equations written in their steady three dimensional form has been applied to the counter rotating vortices for the afore-mentioned experimental conditions. Calculations start from the experimental data obtained at the first measurement station. The calculations are carried out taking into account a lower boundary moving at the same velocity as the flow.
KeywordsTest Section Vortex Core Vortex Pair Joint Probability Density Function Ground Effect
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Physicists at the University of Greifswald have investigated the smallest lead particles and found surprising decay pathways. They report their results in a series of publications, most recently in the journal Physical Review Letters.
Physicists distinguish between the size ranges of individual atoms and bulk matter. Between these, there are also so-called clusters, particles that can be made up of just a few and up to around a thousand atoms. Due to their size they have properties that differ from individual atoms and the bulk matter.
The Figure on the left is a schematic depiction of the laser irradiation of lead particles stored in a so-called Penning ion trap.
Grafik: Stephan König
And what is more, adding or removing just a single atom can substantially change the properties of a cluster. The study of cluster properties is one of the main research areas of the atomic and molecular physics group at the University of Greifswald’s Institute of Physics.
For the investigations that have now been presented, a high-purity lead wire was irradiated with laser pulses. This resulted in a plasma made up of electrons and lead atoms, some of them ionized. The plasma underwent strong cooling which allowed the lead atoms to aggregate, i.e. to form clusters.
The negatively charged clusters were captured in ion traps, further prepared for the actual measurements, and finally the reaction products were analyzed using mass spectrometry.
It had previously been observed that electron and laser irradiation of small negatively charged lead clusters made up of about 20 to approximately 40 atoms decay differently from what was known about other metals: Whilst copper, silver and gold clusters emit either single neutral atoms or their surplus electron, the lead clusters decay into bigger fragments (S. König et al., J. Phys. Chem., 2017, M. Wolfram et al, J. Phys. B 2018, S. König et al., Int. J. Mass Spectrom. (2017)). This decay into bigger pieces only disappears when using larger lead clusters resulting in the known evaporation of single atoms, which is also predicted by modelling small metal balls.
Recently, the studies investigating cluster irradiation of lead clusters by electrons and laser beams have been combined. This resulted in the first observation of the fission of multiply charged negative metal clusters. Furthermore, the decay behavior that deviates from that of the noble metal clusters continues, just like the return to the expected behavior with larger clusters.
These results may also be an indication for deviating behavior in further cluster properties. One of the conjectures based on the present observations is a semiconductor-to-metal transition with increasing size of the lead clusters, whilst even the smallest noble-metal clusters show a metallic behavior.
These results from fundamental research are of interest, for example, to scientists performing research into material science, who are looking for materials with new properties. Nanoparticles are particularly promising. Ideally, their properties could be controlled by their cluster size – although there is still a long way to go before the results can be applied to everyday devices.
The results on fission of multiply charged negative lead clusters appeared in the journal Physical Review Letters 120, 163001 – Published 16 April 2018
Fission of polyanionic metal clusters, S. König, A. Jankowski, G. Marx, L. Schweikhard, M. Wolfram, Physical Review Letters 120, 163001 (2018)
The photos can be downloaded and used for free for editorial purposes in combination with this press release. You must name the respective author of the images. To the photos
Contact at the University of Greifswald
Dr. Stephan König and Prof. Dr. Lutz Schweikhard
Institute of Physics
Felix-Hausdorff-Straße 6, 17487 Greifswald
Tel.: +49 3834 420 4700
Jan Meßerschmidt | idw - Informationsdienst Wissenschaft
Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics
What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin
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
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The Wind Tunnel Fluid Measurements. E80 Spring 2014. Overview. Wind Tunnel Introduction Instrumentation Aerodynamic Theory Safety & Operational Issues. Lab Objectives. Safe operation of the wind tunnel Perform basic airspeed measurements & calibrations
E80 Spring 2014
= static pressure + dynamic pressure
A differential manometer measures the difference between the two pressures which varies according to Bernoulli’s equation
Flow over upper curved surface is faster and the Bernoulli effect results in lower pressure over the top surface
Differences between a Rocket & Airplane?
Lift & drag forces are typically found experimentally rather than integrating pressure & shear stress…
(attributed to Lord Rayleigh)
Ratio of lift or drag force to fluid kinetic energy
Determined experimentally in the wind tunnel
“Skin Friction” Drag
CD = f( fluid velocity v, fluid density r, fluid viscosity m, and cylinder length L)
R. Subramanian. “Dimensional Analysis – Drag on a Sphere.” http://web2.clarkson.edu/projects/subramanian/ch301/notes/dimensionfluids.pdf
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Is energy increasing with angular momentum?
- 29 Downloads
We submit to the community of physicists and mathematical physicists the following problem: prove that the ground-state energy of a system ofN particles without spin, without statistics, and interacting by central forces increases with angular momentum. For two particles, this is obvious. For more than two we give a number of arguments which support our conjecture.
Key WordsMany-body systems Regge trajectories energy dependence on angular momentum comparison between classical and quantum mechanics multidimensional harmonic oscillators
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Pinus species show remarkable ontogenetic differences in needle morphology (heterophylly) between juvenile and adult vegetative phases. This developmental shift may play an adaptative role in their success under diverse habitats. As a first step to know the functional differences between each vegetative phase, we compared water loss through the cuticles of juvenile and adult needles of 21-month-old nursery-grown seedlings of nine hard pine species. Cuticular transpiration (CT), calculated after complete stomatal closure, was obtained by leaf-drying curves, and was related to leaf, ontogenetic and climatic parameters. The rate of cuticular transpiration (RCT) between juvenile and adult needles differed across pine species, and in particular segregated the Mediterranean species Pinus canariensis and P. halepensis, from the Eurasian P. uncinata and introduced species P. radiata. For these species, RCT was always higher in juvenile needles. The different leaf and ontogenic parameters studied were correlated with the variation in RCT among the nine pine species. We discuss this relationship in the light of the species ecology. Besides their possible adaptive interpre- tation, these results suggest an underlying need to consider the ontogenetic heterophylly when assessing functional traits in hard pine seedlings, in particular those traits that govern water relations.
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An international team of scientists using a new X-ray method recorded the internal structure and cell movement inside a living frog embryo in greater detail than ever before.
This result showcases a new method to advance biological research and the search for new treatments for genetic diseases.
Scientists at Northwestern University and the Karlsruher Institut für Technologie in Germany, in collaboration with the Advanced Photon Source at the U.S. Department of Energy’s Argonne National Laboratory, released the most precise depiction ever of the embryonic development of African clawed frogs, one of the most frequently studied model organisms in biology.
The results titled “X-ray phase-contrast in vivo microtomography probes new aspects of Xenopus gastrulation” were published in the journal Nature.
The team X-rayed an embryo during gastrulation, the period when its hundreds of cells start to organize into differentiated tissues that eventually form the nervous system, muscles and internal organs. Studies of African clawed frog embryos can provide clues to the evolution of vertebrates and how human genes turn on or off to create diseases.
Until now, however, it has been difficult to study these embryos. Classical absorption imaging requires a contrast agent and large X-ray dose that can harm living organisms. Researchers from the German synchrotron ANKA proposed a new method of nondestructive analysis using X-ray diffraction. The work was done at the APS outside Chicago because the APS’s high-energy X-rays were required to prevent blurring of the image and damage to the sensitive embryos.
“To obtain the best possible results, a highly coherent high-energy X-ray source with high flux is necessary,” said Xianghui Xiao, a scientist at the APS who collaborated on the work. “The APS is one of only a few X-ray lightsources in the world with this capability. The upgrade of the APS will further improve our ability to study the real-time movement of molecules in living organisms.”
In the experiment, Xiao and his colleagues took regular 15-second exposures separated by periods of 10 minutes over the course of two hours of different gastrulas. The resulting 13 time-lapse scans provided a detailed portrait of the transfiguration of the frog cells.
“The motivation of the experiment was to be able to look at the process of how different larger structures develop at the cellular level in real time,” Xiao said. “What we’re doing is actually a kind of four-dimensional imaging.”
The scientists discovered new morphological structures and clarified the process for redistributing fluid in the embryo. They also were able to locate the areas of the embryo that were driving the migration of tissues and cells during gastrulation
“X-ray diffraction enables high-resolution imaging of soft tissues,” said Ralf Hofmann, one author of the study and a physicist at the Karlsruhe Institute of Technology in Germany. “In our work, we did not only mange to resolve individual cells and parts of their structure, but we could also analyze single cell migration, as well as the movement of cellular networks.”
The research was supported by the Karlsruhe Institute of Technology and the German Federal Ministry of Education and Research.
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Using GPS telemetry data and acoustic propagation modelling, I aim to understand the exposure and behavioural response of grey seals (Halichoerus grypus) to shipping noise. Shipping is a primary source of underwater noise in the ocean and increasingly evidence suggests it can have a detrimental impact on marine life. Grey seals can perceive sound at the same low frequency range emitted by ships and the UK is home to a substantial grey seal population, a protected species under the EU Habitats Directive. However, the UK is also surrounded by some of the world's busiest shipping lanes. Supervised by Dr Clare Embling, Professor Georgy Shapiro, Dr Simon Ingram and Dr Feng Chen, my research aims to improve our understanding of shipping noise and its impacts on grey seals in order to inform effective marine planning and conservation.
Previous research projects include:
- Assessment of acoustic indices for monitoring phylogenetic and temporal patterns of biodiversity in tropical forests.
- Using tri-axial accelerometers and behavioural observation to measure the performance of horses ridden in single-jointed and straight bar snaffle.
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The dominant nitrogen (N) fluxes were simulated in a mountain forest ecosystem on dolomitic bedrock in the Austrian Alps. Based on an existing small-scale climate model the simulation encompassed the present situation and a 50-yr projection. The investigated scenarios were current climate, current N deposition (SC1) and future climate (+2.5 °C and +10% annual precipitation) with three levels of N deposition (SC2, 3, 4). The microbially mediated N transformation, including the emission of nitrogen oxides, was calculated with PnET-N-DNDC. Soil hydrology was calculated with HYDRUS and was used to estimate the leaching of nitrate. The expected change of the forest ecosystem due to changes of the climate and the N availability was simulated with PICUS. The incentive for the project was the fact that forests on dolomitic limestone stock on shallow Rendzic Leptosols that are rich in soil organic matter are considered highly sensitive to the expected environmental changes. The simulation results showed a strong effect due to increased temperatures and to elevated levels of N deposition. The outflux of N, both as nitrate (6-25 kg N ha-1yr-1) and nitrogen oxides (1-2 kg N ha-1yr-1), from the forest ecosystem are expected to increase. Temperature exerts a stronger effect on the N2O emission than the increased rate of N deposition. The main part of the N emission will occur as N2(15 kg N ha-1yr-1). The total N loss is partially offset by increased rates of N uptake in the biomass due to an increase in forest productivity. © 2008 Elsevier Ltd. All rights reserved.
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The largest organisms found on Earth can be determined according to various aspects of an organism's size, such as: mass, volume, area, length, height, or even genome size. Some organisms group together to form a superorganism (such as ants or bees), but such are not classed as single large organisms. The Great Barrier Reef is the world's largest structure composed of living entities, stretching 2,000 km (1,200 mi), but contains many organisms of many types of species.
This article lists the largest species for various types of organisms, and mostly considers extant species. The organism sizes listed are frequently considered "outsized" and are not in the normal size range for the respective group.
If considered singular entities, the largest organisms are clonal colonies which can spread over large areas. Pando, a clonal colony of the quaking aspen tree, is widely considered to be the largest such organism by mass. Even if such colonies are excluded, trees retain their dominance of this listing, with the giant sequoia being the most massive tree. In 2006 a huge clonal colony of Posidonia oceanica was discovered south of the island of Ibiza. At 8 kilometres (5 mi) across, and estimated at around 100,000 years old, it may be one of the largest and oldest clonal colonies on Earth.
Among animals, the largest species are all marine mammals, specifically whales. The blue whale is believed to be the largest animal to have ever lived. The largest land animal classification is also dominated by mammals, with the African bush elephant being the most massive of these.
The largest single-stem tree by wood volume and mass is the giant sequoia (Sequoiadendron giganteum), native to Sierra Nevada and California; it typically grows to a height of 70–85 m (230–280 ft) and 5–7 m (16–23 ft) in diameter.
The largest organism in the world, according to mass, is the aspen tree whose colonies of clones can grow up to five miles long. The largest such colony is Pando, in the Fishlake National Forest in Utah.
Another form of flowering plant that rivals Pando as the largest organism on earth in breadth, if not mass, is the giant marine plant, Posidonia oceanica, discovered in the Mediterranean near the Balearic Islands, Spain. Its length is about 8 km (5 mi). It may also be the oldest living organism in the world, with an estimated age of 100,000 years.
Green algae are photosynthetic unicellular and multicellular protists that are related to land plants. The thallus of the unicellular mermaid's wineglass, Acetabularia, can grow to several inches (perhaps 0.1 to 0.2 m) in length. The fronds of the similarly unicellular, and invasive Caulerpa taxifolia can grow up to a foot (0.3 m) long.
A member of the order Cetacea, the blue whale (Balaenoptera musculus), is thought to be the largest animal ever to have lived. The maximum recorded weight was 190 metric tonnes for a specimen measuring 27.6 metres (91 ft), whereas longer ones, up to 33.6 metres (110 ft), have been recorded but not weighed.
The African bush elephant (Loxodonta africana), of the order Proboscidea, is the largest living land animal. A native of various open habitats in sub-Saharan Africa, this elephant is commonly born weighing about 100 kilograms (220 lb). The largest elephant ever recorded was shot in Angola in 1974. It was a male measuring 10.67 metres (35.0 ft) from trunk to tail and 4.17 metres (13.7 ft) lying on its side in a projected line from the highest point of the shoulder to the base of the forefoot, indicating a standing shoulder height of 3.96 metres (13.0 ft). This male had an computed weight of 12.25 tonnes.
- Table of heaviest living animals
The heaviest living animals are all cetaceans, and thus also the largest living mammals. Since no scale can accommodate the whole body of a large whale, most whales have been weighed by parts.
|Average total length
|1||Blue whale||110||190||24 (79)|
|2||North Pacific right whale||60||120||15.5 (51)|
|3||Southern right whale||58||110||15.25 (50)|
|4||Fin whale||57||120||19.5 (64)|
|5||Bowhead whale||54.5||120||15 (49)|
|6||North Atlantic right whale||54||110||15 (49)|
|7||Sperm whale||31.25||57||13.25 (43.5)|
|8||Humpback whale||29||48||13.5 (44)|
|9||Sei whale||22.5||45||14.8 (49)|
|10||Gray whale||19.5||45||13.5 (44)|
- Table of heaviest terrestrial animals
The following is a list of the heaviest wild land animals, which are all mammals. The African elephant is now listed as two species, the African bush elephant and the African forest elephant, as they are now generally considered to be two separate species.
|Average total length|
|1||African bush elephant||4.9||12.25||6 (19.7)|
|2||Asian elephant||4.15||8.15||6.8 (22.3)|
|3||African forest elephant||2.7||6.0||6.2 (20.3)|
|4||White rhinoceros[dubious ]||2||4.5||4.4 (14.4)|
|5||Indian rhinoceros||1.9||4.0||4.2 (13.8)|
|7||Javan rhinoceros||1.75||2.3||3.8 (12.5)|
|8||Black rhinoceros||1.1||2.9||4 (13.1)|
The largest tunicates are Synoicum pulmonaria, found at depths of 20 and 40 metres (66 and 131 ft), and are up to 14 centimetres (6 in) in diameter. It is also present in the northwestern Atlantic Ocean, around the coasts of Greenland and Newfoundland, but is less common here than in the east, and occurs only at depths between 10 and 13 metres (33 and 43 ft).
- Entergonas (Enterogona)
- The largest entergonas Synoicum pulmonaria it is usually found at depths between about 20 and 40 metres (66 and 131 ft) and can grow to over a metre (yard) in length. It is also present in the northwestern Atlantic Ocean, around the coasts of Greenland and Newfoundland, but is less common here than in the east, and occurs only at depths between 10 and 13 metres (33 and 43 ft).
- Pleurogonas (Pleurogona)
- The largest pleurogonas: Pyura pachydermatina . In colour it is off-white or a garish shade of reddish-purple. The stalk is two thirds to three quarters the length of the whole animal which helps distinguish it from certain invasive tunicates not native to New Zealand such as Styela clava and Pyura stolonifera. It is one of the largest species of tunicates and can grow to over a metre (yard) in length.
- Aspiraculates (Aspiraculata)
- The largest aspiraculates: Oligotrema large and surrounded by six large lobes; the cloacal syphon is small. They live exclusively in deep water and range in size from less than one inch (2 cm) to 2.4 inches (6 cm).
- The largest thaliacean: Pyrosoma atlanticum is cylindrical and can grow up to 60 cm (2 ft) long and 4–6 cm wide. The constituent zooids form a rigid tube, which may be pale pink, yellowish, or bluish. One end of the tube is narrower and is closed, while the other is open and has a strong diaphragm. The outer surface or test is gelatinised and dimpled with backward-pointing, blunt processes. The individual zooids are up to 8.5 mm (0.3 in) long and have a broad, rounded branchial sac with gill slits. Along the side of the branchial sac runs the endostyle, which produces mucus filters. Water is moved through the gill slits into the centre of the cylinder by cilia pulsating rhythmically. Plankton and other food particles are caught in mucus filters in the processes as the colony is propelled through the water. P. atlanticum is bioluminescent and can generate a brilliant blue-green light when stimulated.
- Doliolida (Doliolida)
- The largest doliolida: Doliolida The doliolid body is small, typically 1–2 cm long, and barrel-shaped; it features two wide siphons, one at the front and the other at the back end, and eight or nine circular muscle strands reminiscent of barrel bands. Like all tunicates, they are filter feeders. They are free-floating; the same forced flow of water through their bodies with which they gather plankton is used for propulsion - not unlike a tiny ramjet engine. Doliolids are capable of quick movement. They have a complicated lifecycle consisting of sexual and asexual generations. They are nearly exclusively tropical animals, although a few species can be found as far to the north as northern California.
- Salps (Salpida)
- The largest salps: Cyclosalpa bakeri15cm (6ins) long. There are openings at the anterior and posterior ends of the cylinder which can be opened or closed as needed. The bodies have seven transverse bands of muscle interspersed by white, translucent patches. A stolon grows from near the endostyle (an elongated glandular structure producing mucus for trapping food particles). The stolon is a ribbon-like organ on which a batch of aggregate forms of the animal are produced by budding. The aggregate is the second, colonial form of the salp and is also gelatinous, transparent and flabby. It takes the shape of a radial whorl of individuals up to about 20cm (4in) in diameter. It is formed of approximately 12 zooids linked side by side in a shape that resembles a crown. are largest thetyses: Thetys vagina Individuals can reach up to 30 cm (12 in) long.
- Larvaceans (Larvacea)
- The largest larvaceans: Appendicularia 1 cm (0.39 in) in body length (excluding the tail).
The blue whale is the largest mammal.
The largest land mammal extant today is the African bush elephant. The largest extinct land mammal known was once considered to be Paraceratherium orgosensis, a rhinoceros relative thought to have stood up to 4.8 m (15.7 ft) tall, measured over 7.4 m (24.3 ft) long and may have weighed about 17 tonnes. More recent estimates suggest that Paraceratherium was surpassed by the proboscidean Palaeoloxodon namadicus at about 22 tonnes.
The Permian era Cotylorhynchus, from what is now the southern United States, probably was the largest of all synapsids (most of which became extinct 250 million years ago), at 6 m (20 ft) and 2 tonnes. The largest carnivorous synapsid was Anteosaurus from what is now South Africa during Middle Permian era. Anteosaurus was 5–6 m (16–20 ft) long, and weighed about 500–600 kg (1,100–1,300 lb).
- The largest pelycosaur was the pre-mentioned Cotylorhynchus, and the largest predatory pelycosaurus was Dimetrodon grandis from what is now North America, with a length of 3.1 m (10 ft) and weight of 250 kg (550 lb).
- Moschops was the largest non-mammalian therapsid, with a weight of 700 to 1,000 kg (1,500 to 2,200 lb), and a length of about 5 m (16 ft). The largest carnivorous therapsid was the aforementioned Anteosaurus.
The largest living reptile, a representative of the order Crocodilia, is the saltwater crocodile (Crocodylus porosus) of Southern Asia and Australia, with adult males being typically 3.9–5.5 m (13–18 ft) long. The largest confirmed saltwater crocodile on record was 6.32 m (20.7 ft) long, and weighed about 1,360 kg (3,000 lb). Unconfirmed reports of much larger crocodiles exist, but examinations of incomplete remains have never suggested a length greater than 7 m (23 ft). Also, a living specimen estimated at 7 m (23 ft) and 2,000 kg (4,400 lb) has been accepted by the Guinness Book of World Records. However, due to the difficulty of trapping and measuring a very large living crocodile, the accuracy of these dimensions has yet to be verified. A specimen named Lolong caught alive in the Philippines in 2011 (died February 2013) was found to have measured 6.17 m (20.2 ft) in length.
The Komodo dragon (Varanus komodoensis), also known as the "Komodo monitor", is a large species of lizard found in the Indonesian islands of Komodo, Rinca, Flores, Gili Motang, and Padar. A member of the monitor lizard family (Varanidae), it is the largest living species of lizard, growing to a maximum length of 3 metres (9.8 feet) in rare cases and weighing up to approximately 70 kilograms (150 pounds).
- Table of heaviest living reptiles
The following is a list of the heaviest living reptile species ranked by average weight, which is dominated by the crocodilians. Unlike mammals, birds, or fish, the mass of large reptiles is frequently poorly documented and many are subject to conjecture and estimation.
|Average total length|
|1||Saltwater crocodile||450 (990)||2,000 (4,400)||4.5 (14.8)|
|2||Nile crocodile||410 (900)||1,090 (2,400)||4.2 (13.8)|
|3||Orinoco crocodile||380 (840)||1,100 (2,400)||4.1 (13.5)|
|4||Leatherback sea turtle||364 (800)||932 (2,050)||2.0 (6.6)|
|5||Black caiman||350 (770)||1,100 (2,400)||3.9 (12.8)|
|6||American crocodile||335 (739)||1,000 (2,200)||4.0 (13.1)|
|7||Gharial||250 (550)||977 (2,150)||4.5 (14.8)|
|8||American alligator||240 (530)||1,000 (2,200)||3.4 (11.2)|
|9||Mugger crocodile||225 (495)||700 (1,500)||3.3 (10.8)|
|10||Tomistoma||210 (460)||500 (1,100)||4.0 (13.1)|
|11||Aldabra giant tortoise||205 (450)||360 (790)||1.4 (4.6)|
|12||Loggerhead sea turtle||200 (441)||545 (1202)||0.95 (3.2)|
|13||Green sea turtle||190 (418.9)||395 (870.8)||1.12 (3.67)|
|14||Slender-snouted crocodile||180 (400)||325 (720)||3.3 (10.8)|
|15||Galapagos tortoise||175 (390)||400 (880)||1.5 (4.9)|
- Now extinct, except for birds, which are theropods.
- Sauropods (Sauropoda)
- The largest dinosaurs, and the largest animals to ever live on land, were the plant-eating, long-necked Sauropoda. The tallest and heaviest sauropod known from a complete skeleton is a specimen of an immature Giraffatitan discovered in Tanzania between 1907 and 1912, now mounted in the Museum für Naturkunde of Berlin. It is 12 m (39 ft) tall and weighed 23.3–39.5 tonnes. The longest is a 25 m (82 ft) long specimen of Diplodocus discovered in Wyoming, and mounted in Pittsburgh's Carnegie Natural History Museum in 1907. A Patagotitan specimen found in Argentina in 2014 is estimated to have been 40 m (130 ft) long and 20 m (66 ft) tall, with a weight of 77 tonnes.
- There were larger sauropods, but they are known only from a few bones. The current record-holders include Argentinosaurus, which may have weighed 73 tonnes; Supersaurus which might have reached 34 m (112 ft) in length and Sauroposeidon which might have been 18 m (59 ft) tall. Two other such sauropods include Bruhathkayosaurus and Amphicoelias fragillimus. Both are known only from fragments. Bruhathkayosaurus might have been between 40–44 m (131–144 ft) in length and 175–220 tonnes in weight according to some estimates. A. fragillimus might have been approximately 58 m long and 122.4 metric tons in weight.
- Theropods (Theropoda)
- The largest theropod known from a nearly complete skeleton is the biggest and most complete Tyrannosaurus rex specimen, nicknamed "Sue", which was discovered in South Dakota in 1990 and now mounted in the Field Museum of Chicago at a total length of 12.3 m (40 ft). Body mass estimates have reached over 9,500 kg, though other figures, such as Hartman’s 2013 estimate of 8,400 kg, have been lower.
- Another giant theropod is the semi-aquatic Spinosaurus aegyptiacus from the mid-Cretaceous of North Africa. Size estimates have been fluctuating far more over the years, with length estimates ranging from 12.6 to 18 m and mass estimates from 7 to 20.9 t. Recent findings favour a length exceeding 15 m and a body mass of 7.5 tons.
- Other contenders known from partial skeletons include Giganotosaurus carolinii (est. 12.2–13.2 m and 6-13.8 tonnes) and Carcharodontosaurus saharicus (est. 12-13.3 m and 6.2-15.1 tonnes).
- The largest extant theropod is the Ostrich (see birds, below).
- Armored dinosaurs (Thyreophora)
- The largest thyreophorans were Ankylosaurus and Stegosaurus, from the Late Cretaceous and Late Jurassic periods (respectively) of what is now North America, both measuring up to 9 m (30 ft) in length and estimated to weigh up to 6 tonnes.
- Ornithopods (Ornithopoda)
- The largest ornithopods, were the hadrosaurids Shantungosaurus, a late Cretaceous dinosaur found in the Shandong Peninsula of China, and Magnapaulia from the late Cretaceous of North America. Both species are known from fragmentary remains but are estimated to have reached over 15 m (49 ft) in length and were likely the heaviest non-sauropod dinosaurs, estimated at over 23 tonnes.
- Ceratopsians (Ceratopsia)
- The largest ceratopsians were Triceratops and its ancestor Eotriceratops from the late Cretaceous of North America. Both estimated to have reached about 9 m (30 ft) in length and weighed 12 tonnes.
The largest living bird, a member of the Struthioniformes, is the common ostrich (Struthio camelus), from the plains of Africa and Arabia. A large male ostrich can reach a height of 2.8 m (9.2 ft) and weigh over 156 kg (344 lb). A mass of 200 kg (440 lb) has been cited for the common ostrich but no wild ostriches of this weight have been verified. Eggs laid by the ostrich can weigh 1.4 kg (3.1 lb) and are the largest eggs in the world today.
The largest bird in the fossil record may be the extinct elephant birds (Aepyornis) of Madagascar, which were related to the ostrich. They exceeded 3 m (9.8 ft) in height and 500 kg (1,100 lb). The last of the elephant birds became extinct about 300 years ago. Of almost exactly the same upper proportions as the largest elephant birds was Dromornis stirtoni of Australia, part of a 26,000-year-old group called mihirungs of the family Dromornithidae. The largest carnivorous bird was Brontornis, an extinct flightless bird from South America which reached a weight of 350 to 400 kg (770 to 880 lb) and a height of about 2.8 m (9 ft 2 in). The tallest carnivorous bird was Kelenken, which could reach 3 to 3.2 meters in height and 220 to 250 kilograms. The tallest bird ever was the giant moa (Dinornis maximus), part of the moa family of New Zealand that went extinct around 1500 AD. This particular species of moa stood up to 3.7 m (12 ft) tall, but weighed about half as much as a large elephant bird or mihirung due to its comparatively slender frame.
The heaviest bird ever capable of flight was Argentavis magnificens, the largest member of the now extinct family Teratornithidae, found in Miocene-aged fossil beds of Argentina, with a wingspan up to 5.5 m (18 ft), a length of up to 1.25 m (4.1 ft), a height on the ground of up to 1.75 m (5.7 ft) and a body weight of at least 71 kg (157 lb). Pelagornis sandersi is thought to have had an even larger wingspan of about 6.1–7.4 m (20–24 ft), but is only about 22–40 kg (49–88 lb), half the mass of the former.
- Table of heaviest living birds
The following is a list of the heaviest living bird species ranked by average weight. These species are almost all flightless, which allows for these particular birds to have denser bones and heavier bodies. Flightless birds comprise less than 2% of all living bird species.
|Average total length|
|1||Common ostrich||104 (230)||156.8 (346)||210 (6.9)|
|2||Somali ostrich||90 (200)||130 (287)||200 (6.6)|
|3||Southern cassowary||45 (99)||85 (190)||155 (5.1)|
|4||Northern cassowary||44 (97)||75 (170)||149 (4.9)|
|5||Emu||33 (73)||70 (150)||153 (5)|
|6||Emperor penguin||31.5 (69)||46 (100)||114 (3.7)|
|7||Greater rhea||23 (51)||40 (88)||134 (4.4)|
|8||Dwarf cassowary||19.7 (43)||34 (75)||105 (3.4)|
|9||Lesser rhea||19.6 (43)||28.6 (63)||96 (3.2)|
|10||King penguin||13.6 (30)||20 (44)||92 (3)|
|11||Domesticated turkey||13.5 (29.8) ||39 (86)||100 - 124.9 (3.3 – 4.1)|
|12||Kori bustard||11.4 (25.1)||20 (44.1)||150 (5)|
|13||Great bustard||10.6 (23.4)||21 (46)||115 (3.8)|
|14||Andean condor||8.1 - 14.9 (18-33)||14.9 (33)||100-130 (3.3-4.3)|
|15||Dalmatian Pelican||7.25–15 (16.0–33.1)||15 (33.1)||183 (6)|
The largest living amphibian is the Chinese giant salamander (Andrias davidianus). The maximum size of this nearly human-sized river-dweller is 64 kg (141 lb) and almost 1.83 m (6.0 ft). Before amniotes became the dominant tetrapods, several giant amphibian proto-tetrapods existed and were certainly the dominant animals in their ecosystems. The largest known was the crocodile-like Prionosuchus, which reached a length of 9 m (30 ft).
- Frogs (Anura)
- The largest member of the largest order of amphibians is the African Goliath frog (Conraua goliath). The maximum size this species is verified to attain is a weight of 3.8 kg (8.4 lb) and a snout-to-vent length of 39 cm (15 in). The largest of the toads, the cane toad (Rhinella marina), is also the second largest member of the frog order. This infamous, often invasive species can grow to maximum mass of 2.65 kg (5.8 lb) and measure a maximum of 33 cm (13 in) from snout-to-vent. Rivaling the previous two species, the African bullfrog (Pyxicephalus adspersus) can range up to a weight of 2 kg (4.4 lb) and 25.5 cm (10.0 in) from snout to vent. Another large frog is the largest frog in North America, the American bullfrog, which can reach weights of up to 0.8 kg (1.8 lb) and snout-to-vent-length (SVL) of 20 cm (7.9 in). However, the toad Beelzebufo ampinga, found in fossil from the Cretaceous era in what is now Madagascar, could grow to be 41 cm (16 in) long and weigh up to 4.5 kg (9.9 lb), making it the largest frog ever known. The largest tree frog is the Australasian white-lipped tree frog (Litoria infrafrenata), the females of which can reach a length of 14 cm (5.5 in) from snout to vent and can weigh up to 115 g (4.1 oz). The family Leptodactylidae, one of the most diverse anuran families, also has some very large members. The largest is the Surinam horned frog (Ceratophrys cornuta), which can reach 20 cm (7.9 in) in length from snout to vent and weigh up to 0.48 kg (1.1 lb). While not quite as large as Ceratophrys cornuta, Leptodactylus pentadactylus is often heavier; it can reach 18.5 cm (7.3 in) long and weigh 0.60 kilograms (1.3 pounds). The largest dendrobatid is the Colombian golden poison frog (Phyllobates terribilis), which can attain a length of 6 cm (2.4 in) and nearly 28.3 g (1.00 oz). Most frogs are classified under the suborder Neobatrachia, although nearly 200 species are part of the Mesobatrachia suborder, or ancient frogs. The largest of these are the little-known Brachytarsophrys or Karin Hills frogs, of South Asia, which can grow to a maximum snout-to-vent length of 17 cm (6.7 in) and a maximum weight of 0.54 kg (1.2 lb).
- Caecilians (Gymnophiona)
- The largest of the worm-like caecilians is the Colombian Thompson's caecilian (Caecilia thompsoni), which reaches a length of 1.5 m (4.9 ft), a width of about 4.6 cm (1.8 in) and can weigh up to about 1 kg (2.2 lb).
- Salamanders (Urodela)
- Besides the previously mentioned Chinese giant salamander, the closely related Japanese giant salamander (Andrias japonicus) is also sometimes cited as the largest living amphibian, but salamanders of a greater size than 1.53 m (5.0 ft) and 36 kg (79 lb) have never been verified for this species. Another giant of the amphibian world is the North American Hellbender (Cryptobranchus alleganiensis), which can measure up to 0.76 m (2.5 ft). The largest of the newts is the Iberian ribbed newt (Pleurodeles waltl), which can grow up to 30 cm (12 in) in length.
The largest known species of sea sponge is the giant barrel sponge, Xestospongia muta. These massively built sponges can reach 2.4 m (8 ft) in height and can be of about the same number of feet across at the thickest part of the "body". Some of these creatures have been estimated to be over 2,400 years of age.
- Calcareous sponges (Calcarea)
- The largest known of these small, inconspicuous sponges is probably the species Pericharax heteroraphis, attaining a height of 30 cm (0.98 ft). Most calcareous sponges do not exceed 10 cm (3.9 in) tall.
- Hexactinellid sponges (Hexactinellida)
- A relatively common species, Rhabdocalyptus dawsoni, can reach a height of 1 m (3.3 ft) once they are of a very old age. This is the maximum size recorded for a hexactinellid sponge.
The lion's mane jellyfish (Cyanea capillata) is the largest cnidaria species, of the class Scyphozoa. The largest known specimen of this giant, found washed up on the shore of Massachusetts Bay in 1870, had a bell diameter of 2.5 m (8.2 ft), a weight of 150 kg (330 lb). The tentacles of this specimens were as long as 37 m (121 ft) and were projected to have a tentacular spread of about 75 m (246 ft) making it one of the longest extant animals.
- Corals and sea-anemones (Anthozoa)
- The largest individual species are the sea-anemones of the genus Discoma, which can attain a mouth disc diameter of 60 cm (2.0 ft). Longer, but much less massive overall, are the anemones of the genus Ceriantharia, at up to 2 m (6.6 ft) tall. Communities of coral can be truly massive, a single colony of the genus Porites can be over 10 m (33 ft), but the actual individual organisms are quite small.
- Lion's mane jellyfish
- The largest known species of jellyfish is the "lion's mane jellyfish". The largest of its kind was found in 1870 in Massachusetts Bay with a recorded bell size of 2.3 metres (7 feet 7 inches) and a tentacle length of 37 metres (121 feet).
- Hydrozoans (Hydrozoa)
- The colonial siphonophore Praya dubia can attain lengths of 40–50 m (130–160 ft). The Portuguese man o' war's (Physalia physalis) tentacles can attain a length of up to 50 m (160 ft).
- Monogenean flatworms (Monogenea)
- The largest known members of this group of very small parasites are among the genus of capsalids, Listrocephalos, reaching a length of 2 cm (0.79 in).
- Flukes (Trematoda)
- The largest known species of fluke is Fasciolopsis buski, which most often attacks humans and livestock. One of these flukes can be up to 7.5 cm (3.0 in) long and 2 cm (0.79 in) thick.
- Tapeworms (Cestoda)
- The largest known species of tapeworm is the whale tapeworm, Polygonoporus giganticus, which can grow to over 30 m (98 ft).
The largest of the segmented worms (commonly called earthworms) is the African giant earthworm (Microchaetus rappi). Although it averages about 1.36 m (4.5 ft) in length, this huge worm can reach a length of as much as 6.7 m (22 ft) and can weigh over 1.5 kg (3.3 lb). Only the giant Gippsland earthworm, Megascolides australis, and a few giant polychaetes, including the notorious Eunice aphroditois, reach nearly comparable sizes, reaching 4 and 3.6 m (13 and 12 ft), respectively.
The largest species of echinoderm in terms of bulk is probably the starfish species Thromidia gigas, of the class Asteroidea, which reaches a weight of over 6 kg (13 lb), but it might be beaten by some giant sea cucumbers such as Thelenota anax. However, at a maximum span of 63 cm (25 in), Thromidia gigas is quite a bit shorter than some other echinoderms. The longest echinoderm known is the conspicuous sea cucumber Synapta maculata, with a slender body that can extend up to 3 m (9.8 ft). In comparison, the biggest sea star is the brisingid sea star Midgardia xandaros, reaching a span of 1.4 m (4.6 ft), despite being quite slender. Evasterias echinosoma is another giant echinoderm and can measure up to 1 m (3.3 ft) across and weigh 5.1 kg (11 lb).
- Crinoids (Crinoidea)
- The largest species of crinoid is the unstalked feather-star Heliometra glacialis, reaching a total width of 78 cm (31 in) and an individual arm length of 35 cm (14 in). A width of 91.4 cm (36.0 in) was claimed for one unstalked feather-star but is not confirmed. The genus Metacrinus has a stalk span of 61 cm (24 in) but, due to its bulk and multiple arms, it is heavier than Heliometra. In the past, crinoids grew much larger, and stalk lengths up to 40 m (130 ft) have been found in the fossil record.
- Sea urchins and allies (Echinoidea)
- The largest sea urchin is the species Sperosoma giganteum from the deep northwest Pacific Ocean, which can reach a shell width of about 30 cm (12 in). Another deep sea species Hygrosoma hoplacantha is only slightly smaller. The largest species found along the North America coast is the Pacific red sea urchin (Mesocentrotus franciscanus) where the shell can reach 19 cm (7.5 in). If the spines enter into count, the biggest species may be a Diadematidae like Diadema setosum, with a test up to 10 cm (3.9 in) only, but its spines can reach up to 30 cm (12 in) in length.
- Sea cucumbers (Holothuroidea)
- The bulkiest species of sea cucumber are Stichopus variegatus and Thelenota anax, weighing several pounds, being about 21 cm (8.3 in) in diameter, and reaching a length of 1 m (3.3 ft) when fully extended. Synapta maculata can reach an extended length of 3 m (9.8 ft), but is extremely slender (3-5cm) and weigh much less than Stichopodids.
- Brittle stars (Ophiuroidea)
- The largest known specimen of brittle star is the basket star Astrotoma agassizii. This species can grow to have a span of 1 m (3.3 ft). Sometimes, Gorgonocephalus stimpsoni is considered the largest but the maximum this species is can measure 70 cm (28 in) and a disk diameter of about 14.3 cm (5.6 in). Outside from euryalids, the biggest ophiurid brittle star may be Ophiopsammus maculata (6-7 inches).
- Sea stars (Asteroidea)
- The heaviest sea star is Thromidia gigas from the Indo-Pacific, which can surpass 6 kg (13 lb) in weight, but only has a diameter of about 65 cm (2.13 ft). Despite its relatively small disk and weight, the long slender arms of Midgardia xandaros from the Gulf of California makes it the sea star with the largest diameter at about 1.4 m (4.5 ft). Mithrodia clavigera may also become wider than 1 m (39 in) in some cases, with stout arms.
Both the largest mollusks and the largest of all invertebrates (in terms of mass) are the largest squids. The colossal squid (Mesonychoteuthis hamiltoni) is projected to be the largest invertebrate. Current estimates put its maximum size at 12 to 14 m (39 to 46 ft) long and 750 kg (1,650 lb), based on analysis of smaller specimens. In 2007, authorities in New Zealand announced the capture of the largest known colossal squid specimen. It was initially thought to be 10 m (33 ft) and 450 kg (990 lb). It was later measured at 4.2 m (14 ft) long and 495 kg (1,091 lb) in weight. The mantle was 2.5 m (8.2 ft) long when measured.
The giant squid (Architeuthis dux) was previously thought to be the largest squid, and while it is less massive and has a smaller mantle than the colossal squid, it may exceed the colossal squid in overall length including tentacles. One giant squid specimen that washed ashore in 1878 in Newfoundland reportedly measured 18 m (59 ft) in total length (from the tip of the mantle to the end of the long tentacles), head and body length 6.1 m (20 ft), 4.6 m (15 ft) in diameter at the thickest part of mantle, and weighed about 900 kg (2,000 lb). This specimen is still often cited as the largest invertebrate that has ever been examined. However, no animals approaching this size have been scientifically documented and, according to giant squid expert Steve O'Shea, such lengths were likely achieved by greatly stretching the two tentacles like elastic bands.
- Aplacophorans (Aplacophora)
- The largest known of these worm-like, shell-less mollusks are represented in the genus Epimenia, which can reach 30 cm (12 in) long. Most aplacophorans are less than 5 cm (2.0 in) long.
- Chitons (Polyplacophora)
- The largest of the chitons is the gumboot chiton, Cryptochiton stelleri, which can reach a length of 33 cm (13 in) and weigh over 2 kg (4.4 lb).
- Bivalves (Bivalvia)
- The largest of the bivalve mollusks is the giant clam, Tridacna gigas. Although even larger sizes have been reported for this passive animal, the top verified size was for a specimen from the Great Barrier Reef. This creature weighed 270 kg (600 lb), had an axial length of 1.14 m (3.7 ft) and depth of 0.75 m (2.5 ft). The largest bivalve ever was Platyceramus platinus, a Cretaceous giant that reached an axial length of up to 3 m (nearly 10 ft).
- Gastropods (Gastropoda)
- The "largest" of this most diverse and successful mollusk class of slugs and snails can be defined in various ways.
- The living gastropod species that has the largest (longest) shell is Syrinx aruanus with a maximum shell length of 0.91 m (3.0 ft), a weight of 18 kg (40 lb) and a width of 96 cm (38 in). Another giant species is Melo amphora, which in a 1974 specimen from West Australia, measured 0.71 m (2.3 ft) long, had a maximum girth of 0.97 m (3.2 ft) and weighed 16 kg (35 lb).
- The largest shell-less gastropod is the giant black sea hare (Aplysia vaccaria) at 0.99 m (3.2 ft) in length and almost 14 kg (31 lb) in weight.
- The largest of the land snails is the giant African snail (Achatina achatina) at up to 1 kg (2.2 lb) and 35 cm (14 in) long.
- Cephalopods (Cephalopoda)
- (See Cephalopod size.) While generally much smaller than the giant Architeuthis and Mesonychoteuthis, the largest of the octopuses, the giant Pacific octopus (Enteroctopus dofleini), can grow to be very large. The largest confirmed weight of a giant octopus is 74 kg (163 lb), with a 7 m (23 ft) arm span (with the tentacles fully extended) and a head-to-tentacle-tip length of 3.9 m (13 ft). Specimens have been reported up to 125 kg (276 lb) but are unverified.
Velvet worms (Onychophora)Edit
The largest arthropod known to have existed is the eurypterid (sea scorpion) Jaekelopterus, reaching up to 2.5 m (8.2 ft) in body length, followed by the millipede relative Arthropleura at around 2.1 m (6.9 ft) in length. Among living arthropods, the Japanese spider crab (Macrocheira kaempferi) is the largest in overall size, the record specimen, caught in 1921, had an extended arm span of 3.8 m (12 ft) and weighed about 19 kg (42 lb). The heaviest is the American lobster (Homarus americanus), the largest verified specimen, caught in 1977 off of Nova Scotia weighed 20 kg (44 lb) and its body length was 1.1 m (3.6 ft). The largest land arthropod and the largest land invertebrate is the coconut crab (Birgus latro), up to 40 cm (1.3 ft) long and weighing up to 4 kg (8.8 lb) on average. Its legs may span 1 m (3.3 ft).
- Both spiders and scorpions include contenders for the largest arachnids.
- Spiders (Araneae)
- The largest species of arachnid by length is probably the giant huntsman spider (Heteropoda maxima) of Laos, which in 2008 replaced the Goliath birdeater (Theraphosa blondi) of northern South America as the largest known spider by leg-span. However the most massive arachnids, of comparable dimensions and possibly even greater mass, are the Chaco golden knee, Grammostola pulchripes, and the Brazilian salmon pink, Lasiodora parahybana. The huntsman spider may span up to 29 cm (11 in) across the legs, while in the New World "tarantulas" like Theraphosa can range up to 26 cm (10 in). In Grammostola, Theraphosa and Lasiodora, the weight is projected to be up to at least 150 g (5.3 oz) and body length is up to 10 cm (3.9 in).
- Scorpions (Scorpiones)
- The largest of the scorpions is the species Heterometrus swammerdami of the Indian subcontinent, which have a maximum length of 29.2 cm (11.5 in) and weigh around 60 g (2.1 oz). Another extremely large scorpion is the African emperor scorpion (Pandinus imperator), which can weigh 57 g (2.0 oz) but is not known to exceed a length of 23 cm (9.1 in). However, they were dwarfed by Pulmonoscorpius kirktonensis, a giant extinct species of scorpion from Scotland, at an estimated length of 0.7 m (2.3 ft) and weight of 15 kg (33 lb)[unreliable source?], and the aquatic Brontoscorpio, at up to 1 m (3.3 ft) and a similar weight.
- Pseudoscorpions (Pseudoscorpiones))
- The largest pseudoscorpion is Garypus titanius, from Ascension island, which can be 12 mm (0.47 in) long.
- The largest crustaceans are crab Tasmanian giant crab (''Pseudocarcinus gigas) 13 kilograms (29 lb) and a carapace width of up to 46 centimetres (18 in). It is the only species in the genus Pseudocarcinus. Males reach more than twice the size of females. It has a white shell with claws that are splashed in red. The females' shells change colour when they are producing eggs. Lysiosquillina maculataAt a length of up to 40 cm, L. maculata is the largest mantis shrimp in the world. L. maculata may be distinguished from its congener L. sulcata by the greater number of teeth on the last segment of its raptorial claw, and by the colouration of the uropodal endopod, the distal half of which is dark in L. maculata but not in L. sulcata. There is a small artisanal fishery for this species. are largest shrimps Tasmanian giant freshwater crayfish (Astacopsis gouldi) 5 kilograms (11 lb) in weight and over 80 centimetres (31 in) long have been known in the past, but now, even individuals over 2 kilograms (4.4 lb) are rare. The species is only found in Tasmanian rivers flowing north into the Bass Strait below 400 metres (1,300 ft) above sea level, and is listed as an endangered species on the IUCN Red List.
- Branchiopods (Branchiopoda)
- The largest of these primarily freshwater crustaceans is probably Branchinecta gigas, which can reach a length 10 cm (3.9 in).
- Barnacles and allies (Maxillopoda)
- The largest species is a copepod (Pennella balaenopterae), known exclusively as a parasite from the backs of fin whales (Balaenoptera physalus). The maximum size attained is 32 cm (about 13 in). The largest of the barnacles is the giant acorn barnacle, Balanus nubilis, reaching 7 cm (2.8 in) in diameter and 12.7 cm (5.0 in) high.
- Ostracods (Ostracoda)
- The largest living representative of these small and little-known but numerous crustaceans is the species Gigantocypris australis females of which reaching a maximum length of 3 cm (1.2 in).
- Amphipods, isopods, and allies (Peracarida)
- The largest species is the giant isopod (Bathynomus pergiganteus), which can reach a length of 45 cm (18 inches) and a weight of 1.7 kg (3.7 lb).
- Remipedes (Remipedia)
- The largest of these cave-dwelling crustaceans is the species Godzillius robustus, at up to 4.5 cm (1.8 in).
Horseshoe crabs (Merostomata)Edit
- The four modern horseshoe crabs are of roughly the same sizes, with females measuring up to 60 cm (2.0 ft) in length and 5 kg (11 lb) in weight.
Sea spiders (Pycnogonida)Edit
- The largest of the sea spiders is the deep-sea species Colossendeis colossea, attaining a leg span of nearly 60 cm (2.0 ft).
- Some of these extinct marine arthropods exceeded 60 cm (24 in) in length. A nearly complete specimen of Isotelus rex from Manitoba attained a length over 70 cm (28 in), and an Ogyginus forteyi from Portugal was almost as long. Fragments of trilobites suggest even larger record sizes. An isolated pygidium of Hungioides bohemicus implies that the full animal was 90 cm (35 in) long.
- Centipedes (Chilopoda)
- The biggest of the centipedes is Scolopendra gigantea of the neotropics, reaching a length of 33 cm (13 in).
- Millipedes (Diplopoda)
- Two species of millipede both reach a very large size Archispirostreptus gigas of East Africa and Scaphistostreptus seychellarum, endemic to the Seychelles islands. Both of these species can slightly exceed a length of 28 cm (11 in) and measure over 2 cm (0.79 in) in diameter. The largest ever known was the Arthropleura, a gigantic prehistoric specimen that reached nearly 6.2 feet.
Insects, a class of Arthropoda, are easily the most numerous class of organisms, with over one million identified species, and probably many undescribed species. The heaviest insect is almost certainly a species of beetle, which incidentally is the most species-rich order of organisms. Although heavyweight giant wetas (Deinacrida heteracantha) are known, the elephant beetles of Central and South America, (Megasoma elephas) and (M. actaeon), the Titan beetle (Titanus giganteus) of the neotropical rainforests or the Goliath beetles, (Goliathus goliatus) and (G. regius), of Africa's rainforests are thought to reach a higher weight. The most frequently crowned are the Goliath beetles, the top known size of which is at least 100 g (3.5 oz) and 11.5 cm (4.5 in). The elephant beetles and titan beetle can reach greater lengths than the Goliath, at up to 13.1 and 15.2 cm (5.2 and 6.0 in), respectively, but this is in part thanks to their rather large horns. The Goliath beetle's wingspan can range up to 25 cm (9.8 in).
Some moths and butterflies have much larger areas than the heaviest beetles, but weigh a fraction as much.
The longest insects are the stick insects, see below.
Representatives of the extinct dragonfly-like order Protodonata such as the Carboniferous Meganeura monyi of what is now France and the Permian Meganeuropsis permiana of what is now North America are the largest insect species yet known to have existed. These creatures had a wingspan of some 75 cm (30 in) and a mass of over 1 pound (450 g), making them about the size of a crow.
- Cockroaches and termites (Blattodea)
- The largest cockroach is the Australian giant burrowing cockroach (Macropanesthia rhinoceros). This species can attain a length of 8.3 cm (3.3 in) and a weight of 36 g (1.3 oz). The giant cockroach (Blaberus giganteus) of the neotropics reaches comparable lengths although is not as massive as the burrowing species. The termites, traditionally classified in their own order (Isoptera), have recently been re-considered to belong in Blattodea. The largest of the termites is the African species Macrotermes bellicosus. The queen of this species can attain a length of 14 cm (5.5 in) and breadth of 5.5 cm (2.2 in) across the abdomen; other adults, on the other hand, are about a third of the size.
- Beetles (Coleoptera)
- The beetles are the largest order of organisms on earth, with about 400,000 species so far identified. The most massive species are the Goliathus, Megasoma and Titanus beetles already mentioned. Another fairly large species is the Hercules beetle (Dynastes hercules) of the neotropic rainforests with a maximum overall length of at least 19 cm (7.5 in) including the extremely long pronotal horn. The weight in this species does not exceed 16.5 g (0.58 oz). The longest overall beetle is a species of longhorn beetle, Batocera wallacei, from New Guinea, which can attain a length of 26.6 cm (10.5 in), about 19 cm (7.5 in) of which is comprised by the long antennae.
- Earwigs (Dermaptera)
- The largest of the earwigs is the Saint Helena giant earwig (Labidura herculeana), endemic to the island of its name, which is up to 8 cm (3.1 in) in length.
- True flies (Diptera)
- The largest species of this order, which includes the common housefly, is the neotropical species Gauromydas heros, which can reach a length of 6 cm (2 3⁄8 in) and a wingspan of 10 cm (3.9 in). Species of crane fly, the largest of which is Holorusia brobdignagius, can attain a length of 23 cm (9.1 in) but are extremely slender and much lighter in weight than Gauromydas.
- Mayflies (Ephemeroptera)
- The largest mayflies are members of the genus Proboscidoplocia from Madagascar. These insects can reach a length of 7 cm (2.8 in).
- True bugs (Hemiptera)
- The largest species of this diverse order is usually listed as the giant water bug in the genus Lethocerus, with L. maximus from the Neotropics being the absolutely largest. They can surpass 12 cm (4.7 in) in length, with some suggesting that the maximum size is 15 cm (5.9 in). It is more slender and less heavy than most other insects of this size (principally the huge beetles). The largest cicada is Megapomponia imperatoria, which has a head-body length of about 7 cm (2.8 in) and a wingspan of 18–20 cm (7–8 in). The cicadas of the genus Tacua can also grow to comparably large sizes. The largest type of aphid is the giant oak aphid (Stomaphis quercus), which can reach an overall length of 2 cm (0.79 in). The biggest species of leafhopper is Ledromorpha planirostris, which can reach a length of 2.8 cm (1.1 in).
- Ants and allies (Hymenoptera)
- The largest of the ants, and the heaviest species of the order, are the females of the African Dorylus helvolus, reaching a length of 5.1 cm (2.0 in) and a weight of 8.5 g (0.30 oz). The ant that averages the largest for the mean size within the whole colony is a ponerine ant, Dinoponera gigantea, from South America, averaging up to 3.3 cm (1.3 in) from the mandibles to the end of abdomen. Workers of the bulldog ant (Myrmecia brevinoda) of Australia are up to 3.7 cm (1.5 in) in total length, although much of this is from their extremely large mandibles. The largest of the bee species, also in the order Hymenoptera, is Megachile pluto of Indonesia, the females of which can be 3.8 cm (1.5 in) long, with a 6.3 cm (2.5 in) wingspan. Nearly as large, the carpenter bees can range up to 2.53 cm (1.00 in). The largest wasp is probably the so-called tarantula hawk species Pepsis pulszkyi of South America, at up to 6.8 cm (2.7 in) long and 11.6 cm (4.6 in) wingspan, although many other Pepsis approach a similar size. The giant scarab-hunting wasp Megascolia procer may rival the largest tarantula hawks in weight and wingspan, though its body is not as long.
- Moths and allies (Lepidoptera)
- The Hercules moth (Coscinocera hercules), in the family Saturniidae, is endemic to New Guinea and northern Australia, and its wings have the largest documented surface area (300 square centimeters) of any living insect, and a maximum wingspan which is confirmed to 28 cm (11 in) while unconfirmed specimens have spanned up to 35.5 cm (14.0 in). The largest species overall is often claimed to be either the Queen Alexandra's birdwing (Ornithoptera alexandrae), a butterfly from Papua New Guinea, or the Atlas moth (Attacus atlas), a moth from Southeast Asia. Both of these species can reach a length of 8 cm (3.1 in), a wingspan of 28 cm (11 in) and a weight of 12 g (0.42 oz). One Atlas moth allegedly had a wingspan of 30 cm (12 in) but this measurement was not verified. The larvae in the previous species can weigh up to 58 and 54 g (2.0 and 1.9 oz), respectively. However, there are no reported measurements of surface area that would exceed the Hercules moth, and the white witch (Thysania agrippina) of Central and South America, has the largest recorded wingspan of the order, and indeed of any living insect, though the white witch is exceeded in surface area by the Hercules moth. The verified record-sized Thysania spanned 30.8 cm (12.1 in) across the wings, although specimens have been reported to 36 cm (14 in). The heaviest mature moths have been cited in the giant carpenter moth (Xyleutes boisduvali) of Australia, which has weighed up to 20 g (0.71 oz) although the species does not surpass 25.5 cm (10.0 in) in wingspan.
- Mantises (Mantodea)
- The largest species of this order is Toxodera denticulata from Java, which has been measured up to 20 cm (7.9 in) in overall length. However, an undescribed species from the Cameroon jungle is allegedly much larger than any other mantis and may rival the larger stick insects for the longest living insect. Among widespread mantis species, the largest is the Chinese mantis (Tenodera aridifolia). The females of this species can attain a length of up to 10.6 cm (4.2 in).
- Alderflies and allies (Megaloptera)
- This relatively small insect order includes some rather large species, many of which are noticeable for their elongated, imposing mandibles. The dobsonflies reach the greatest sizes of the order and can range up to 12.5 cm (4.9 in) in length.
- Net-winged insects (Neuroptera)
- These flying insects reach their largest size in Palparellus voeltzkowi, which can have a wingspan over 16 cm (6.3 in). The largest lacewing is the "blue eyes lacewing" (Nymphes myrmeleonides) of Australia, which can measure up to 4 cm (1.6 in) in length and span 11 cm (4.3 in) across the wings. Some forms of this ancient order could grow extremely large during the Jurassic Era and may have ranked among the largest insects ever.
- Dragonflies (Odonata)
- The largest living species of dragonfly is Megaloprepus caerulatus of the neotropics, attaining a size of as much as 19 cm (7.5 in) across the wings and a body length of over 12 cm (4.7 in). Spanning up to 17.6 cm (6.9 in) and measuring up to 11.8 cm (4.6 in) long, Tetracanthagyna plagiata of Southeast Asia is bulkier and heavier than Megaloprepus at up to 7 g (0.25 oz). The largest species of dragonfly ever is the extinct aforementioned Meganeura, although it is not certain to be included in the modern dragonfly order.
- Grasshoppers and allies (Orthoptera)
- The largest of this widespread, varied complex of insects are the giant wetas of New Zealand, which is now split among 12 species. The largest of these is the Little Barrier Island giant weta (Deinacrida heteracantha), the largest specimen was weighed at 71.3 g (2.52 oz), one of the largest insects weights ever known. These heavyweight insects can be over 9 cm (3.5 in) long. The largest grasshopper species is often considered to be the Australian giant grasshopper (Valanga irregularis), which ranges up to 9 cm (3.5 in) in length. The American eastern lubber grasshopper (Romalea guttata) can allegedly range up to 10 cm (3.9 in) in length. However, the greatest grasshopper sizes known, to 12 cm (4.7 in), have been cited in the South American giant grasshopper (Tropidacris violaceus). The longest members of this order (although much lighter than the giant wetas) is the katydid Macrolyristes corporalis of Southeast Asia which can range up to 21.5 cm (8.5 in) with its long legs extended and can have a wingspan of 20 cm (7.9 in).
- Stick insects (Phasmatodea)
- The longest known stick insect, and indeed the longest insect ever known, is Phobaeticus chani of the Bornean rainforests, with one specimen held in the Natural History Museum in London measuring 56.7 cm (22.3 in) in total length. This measurement is, however, with the front legs fully extended. The body alone still measures 35.7 cm (14.1 in). The species with the second longest body is Phobaeticus kirbyi, also of Borneo, which measures up to 32.8 cm (12.9 in), while the overall length (from the hind to the front legs) is up to 54.6 cm (21.5 in). The second longest insect in terms of total length is Phobaeticus serratipes of Malaysia and Singapore, measuring up to 55.5 cm (21.9 in). Another extremely long stick insect is Pharnacia maxima, which measured 51 cm (20 in) with its legs extended. The spiny stick insect (Heteropteryx dilatata) of Malaysia does not reach the extreme lengths of its cousins, the body reaching up to 16 cm (6.3 in) long, but it is much bulkier. The largest Heteropteryx weighed about 65 g (2.3 oz) and was 3.5 cm (1.4 in) wide across the thickest part of the body.
- Lice (Phthiraptera)
- These insects, which live parasitically on other animals, are as a rule quite small. The largest known species is the hog louse, Haematopinus suis, a sucking louse that lives on large livestock like pigs and cattle. It can range up to 6 mm (0.24 in) in length.
- Stoneflies (Plecoptera)
- The largest species of stonefly is Pteronarcys californica of western North America, a species favored by fishermen as lures. This species can attain a length of 5 cm (2.0 in) and a wingspan of over 9.5 cm (3.7 in).
- Booklice (Psocoptera)
- The largest of this order of very small insects are the barklice of the genus Psocus, the top size of which is about 1 cm.
- Fleas (Siphonaptera)
- The largest species of flea is Hystrichopsylla schefferi. This parasite is known exclusively from the fur of the mountain beaver (Aplodontia rufa) and can reach a length of 1.2 cm (0.47 in).
- Silverfishes and allies (Thysanura)
- These strange-looking insects, known to feed on human household objects, can range up to 4.3 cm (1.7 in) in length. A 350 million year old form was known to grow quite large, at up to 6 cm (2.4 in).
- Thrips (Thysanoptera)
- Members of the genus Phasmothrips are the largest kinds of thrips. The maximum size these species attain is approximately 1.3 cm (0.51 in) in length.
- Caddisflies (Trichoptera)
The largest living fungus may be a honey fungus of the species Armillaria ostoyae. A mushroom of this type in the Malheur National Forest in the Blue Mountains of eastern Oregon, U.S. was found to be the largest fungal colony in the world, spanning 8.9 km2 (2,200 acres) of area. This organism is estimated to be 2,400 years old. The fungus was written about in the April 2003 issue of the Canadian Journal of Forest Research. While an accurate estimate has not been made, the total weight of the colony may be as much as 605 tons[vague]. If this colony is considered a single organism, then it is the largest known organism in the world by area, and rivals the aspen grove "Pando" as the known organism with the highest living biomass. It is not known, however, whether it is a single organism with all parts of the mycelium connected.
In Armillaria ostoyae, each individual mushroom (the fruiting body, similar to a flower on a plant) has only a 5 cm (2.0 in) stipe, and a pileus up to 12.5 cm (4.9 in) across. There are many other fungi which produce a larger individual size mushroom. The largest known fruiting body of a fungus is a specimen of Phellinus ellipsoideus (formerly Fomitiporia ellipsoidea) found on Hainan Island. The fruiting body masses up to 500 kg (1,100 lb).
Until P. ellipsoideus replaced it, the largest individual fruit body came from Rigidoporus ulmarius. R. ulmarius can grow up to 284 kg (626 lb), 1.66 m (5.4 ft) tall, 1.46 m (4.8 ft) across, and has a circumference of up to 4.9 m (16 ft).
(Note: the group Protista is not used in current taxonomy.)
- Among the organisms that are not multicellular, the largest are the slime moulds, such as Physarum polycephalum, some of which can reach a diameter over 30 cm (12 in). These organisms are unicellular, but they are multinucleate.
- The largest species traditionally considered protozoa are giant amoeboids like foraminiferans. One such species, the xenophyophore Syringammina fragilissima, can attain a size of 20 cm (7.9 in).
The largest known species of bacterium is Thiomargarita namibiensis, which grows to 0.75 mm (0.030 in) in diameter, making it visible to the naked eye and a thousand times the size of more typical bacteria.
The largest virus on record so far is the Pithovirus sibericum with the length of 1.5 micrometres, comparable to the typical size of a bacterium and large enough to be seen in light microscopes. It was discovered in March 2014 in a soil sample collected from a riverbank in Siberia. Prior to this discovery, the largest virus was the peculiar virus genus Pandoravirus, which have a size of approximately 1 micrometer and whose genome contains 1,900,000 to 2,500,000 base pairs of DNA.
Both these viruses infect amoebas specifically.
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Effect of fire on fine root density in red shank (Adenostoma sparsifolium Torr.) chaparral
In December 1981 a 2 ha site of 54-yr southern California chaparral was burned. A frequent species on this site wasAdenostoma sparsifolium. This shrub regenerates after fire with stump sprouting. The total fine root (diam. <1.0 mm) density of the matureA. sparsifolium stand was estimated to be 50–100 g m−2. This value was obtained in late summer. At this time fine root density in chaparral is at its lowest. In the growing season after the burn no signs for reduced fine root density were detected. Indeed, indications for a fire-enchanced flush of fine root growth were found.
Key wordsAdenostoma sparsifolium Brush fire Chaparral Fine roots Ingrowth cores Root biomass Soil cores
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Energy-optimal gait analysis of quadruped robots
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It is important for walking robots such as quadruped robots to have an efficient gait. Since animals and insects are the basic models for most walking robots, their walking patterns are good examples. In this study, the walking energy consumption of a quadruped robot is analyzed and compared with natural animal gaits. Genetic algorithms have been applied to obtain the energy-optimal gait when the quadruped robot is walking with a set velocity. In this method, an individual in a population represents the walking pattern of the quadruped robot. The gait (individual) which consumes the least energy is considered to be the best gait (individual) in this study. The energy-optimal gait is analyzed at several walking velocities, since the amount of walking energy consumption changes if the walking velocity of the robot is changed. The results of this study can be used to decide what type of gait should be generated for a quadruped robot as its walking velocity changes.
Key wordsQuadruped robot Optimal gait Energy analysis Animal gait Genetic algorithms
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The elementary charge, usually denoted as e or sometimes q, is the electric charge carried by a single proton, or equivalently, the magnitude of the electric charge carried by a single electron, which has charge −e. This elementary charge is a fundamental physical constant. To avoid confusion over its sign, e is sometimes called the elementary positive charge. This charge has a measured value of approximately 1766208(98)×10−19 C, 1.602 and after the planned redefinition of SI base units in 2018-2019, its value will be exactly 1.602 176 634×10−19 C by definition of the coulomb. In cgs units, it is 20425(10)×10−10 statcoulombs. 4.803
|Elementary electric charge|
|Definition:||Charge of a proton|
|Symbol||e or sometimes q|
|Value in coulombs:||1766208(98)×10−19 C1.602|
As a unitEdit
|Elementary charge (as a unit of charge)|
|Unit system||Atomic units|
|Unit of||electric charge|
|Symbol||e or q|
|1 e or q in ...||... is equal to ...|
In some natural unit systems, such as the system of atomic units, e functions as the unit of electric charge, that is e is equal to 1 e in those unit systems. The use of elementary charge as a unit was promoted by George Johnstone Stoney in 1874 for the first system of natural units, called Stoney units. Later, he proposed the name electron for this unit. At the time, the particle we now call the electron was not yet discovered and the difference between the particle electron and the unit of charge electron was still blurred. Later, the name electron was assigned to the particle and the unit of charge e lost its name. However, the unit of energy electronvolt reminds us that the elementary charge was once called electron.
Charge quantization is the principle that the charge of any object is an integer multiple of the elementary charge. Thus, an object's charge can be exactly 0 e, or exactly 1 e, −1 e, 2 e, etc., but not, say, 1/ e, or −3.8 e, etc. (There may be exceptions to this statement, depending on how "object" is defined; see below.)
This is the reason for the terminology "elementary charge": it is meant to imply that it is an indivisible unit of charge.
Charges less than an elementary chargeEdit
- Quarks, first posited in the 1960s, have quantized charge, but the charge is quantized into multiples of 1/ e. However, quarks cannot be seen as isolated particles; they exist only in groupings, and stable groupings of quarks (such as a proton, which consists of three quarks) all have charges that are integer multiples of e. For this reason, either 1 e or 1/ e can be justifiably considered to be "the quantum of charge", depending on the context. This charge commensurability, "charge quantization", has partially motivated Grand unified Theories.
- Quasiparticles are not particles as such, but rather an emergent entity in a complex material system that behaves like a particle. In 1982 Robert Laughlin explained the fractional quantum Hall effect by postulating the existence of fractionally-charged quasiparticles. This theory is now widely accepted, but this is not considered to be a violation of the principle of charge quantization, since quasiparticles are not elementary particles.
What is the quantum of charge?Edit
All known elementary particles, including quarks, have charges that are integer multiples of 1/ e. Therefore, one can say that the "quantum of charge" is 1/ e. In this case, one says that the "elementary charge" is three times as large as the "quantum of charge".
On the other hand, all isolatable particles have charges that are integer multiples of e. (Quarks cannot be isolated: they only exist in collective states like protons that have total charges that are integer multiples of e.) Therefore, one can say that the "quantum of charge" is e, with the proviso that quarks are not to be included. In this case, "elementary charge" would be synonymous with the "quantum of charge".
In fact, both terminologies are used. For this reason, phrases like "the quantum of charge" or "the indivisible unit of charge" can be ambiguous, unless further specification is given. On the other hand, the term "elementary charge" is unambiguous: it refers to a quantity of charge equal to that of a proton.
Experimental measurements of the elementary chargeEdit
In terms of the Avogadro constant and Faraday constantEdit
(In other words, the charge of one mole of electrons, divided by the number of electrons in a mole, equals the charge of a single electron.)
This method is not how the most accurate values are measured today: Nevertheless, it is a legitimate and still quite accurate method, and experimental methodologies are described below:
The value of the Avogadro constant NA was first approximated by Johann Josef Loschmidt who, in 1865, estimated the average diameter of the molecules in air by a method that is equivalent to calculating the number of particles in a given volume of gas. Today the value of NA can be measured at very high accuracy by taking an extremely pure crystal (often silicon), measuring how far apart the atoms are spaced using X-ray diffraction or another method, and accurately measuring the density of the crystal. From this information, one can deduce the mass (m) of a single atom; and since the molar mass (M) is known, the number of atoms in a mole can be calculated: NA = M/m.
The value of F can be measured directly using Faraday's laws of electrolysis. Faraday's laws of electrolysis are quantitative relationships based on the electrochemical researches published by Michael Faraday in 1834. In an electrolysis experiment, there is a one-to-one correspondence between the electrons passing through the anode-to-cathode wire and the ions that plate onto or off of the anode or cathode. Measuring the mass change of the anode or cathode, and the total charge passing through the wire (which can be measured as the time-integral of electric current), and also taking into account the molar mass of the ions, one can deduce F.
The limit to the precision of the method is the measurement of F: the best experimental value has a relative uncertainty of 1.6 ppm, about thirty times higher than other modern methods of measuring or calculating the elementary charge.
A famous method for measuring e is Millikan's oil-drop experiment. A small drop of oil in an electric field would move at a rate that balanced the forces of gravity, viscosity (of traveling through the air), and electric force. The forces due to gravity and viscosity could be calculated based on the size and velocity of the oil drop, so electric force could be deduced. Since electric force, in turn, is the product of the electric charge and the known electric field, the electric charge of the oil drop could be accurately computed. By measuring the charges of many different oil drops, it can be seen that the charges are all integer multiples of a single small charge, namely e.
The necessity of measuring the size of the oil droplets can be eliminated by using tiny plastic spheres of a uniform size. The force due to viscosity can be eliminated by adjusting the strength of the electric field so that the sphere hovers motionless.
Any electric current will be associated with noise from a variety of sources, one of which is shot noise. Shot noise exists because a current is not a smooth continual flow; instead, a current is made up of discrete electrons that pass by one at a time. By carefully analyzing the noise of a current, the charge of an electron can be calculated. This method, first proposed by Walter H. Schottky, can determine a value of e of which the accuracy is limited to a few percent. However, it was used in the first direct observation of Laughlin quasiparticles, implicated in the fractional quantum Hall effect.
From the Josephson and von Klitzing constantsEdit
Another accurate method for measuring the elementary charge is by inferring it from measurements of two effects in quantum mechanics: The Josephson effect, voltage oscillations that arise in certain superconducting structures; and the quantum Hall effect, a quantum effect of electrons at low temperatures, strong magnetic fields, and confinement into two dimensions. The Josephson constant is
The von Klitzing constant is
It can be measured directly using the quantum Hall effect.
From these two constants, the elementary charge can be deduced:
where h is the Planck constant, α is the fine-structure constant, μ0 is the magnetic constant, ε0 is the electric constant and c is the speed of light. The uncertainty in the value of e is currently determined almost entirely by the uncertainty in the Planck constant.
The most precise values of the Planck constant come from Kibble balance experiments, which are used to measure the product K2
JRK. The most precise values of the fine structure constant come from comparisons of the measured and calculated value of the gyromagnetic ratio of the electron.
- "CODATA Value: elementary charge". The NIST Reference on Constants, Units, and Uncertainty. US National Institute of Standards and Technology. June 2015. Retrieved 2015-09-22.
2014 CODATA recommended values
- Note that the symbol e has many other meanings. Somewhat confusingly, in atomic physics, e sometimes denotes the electron charge, i.e. the negative of the elementary charge.
- This is derived from the NIST value and uncertainty, using the fact that one coulomb is exactly 997924580 statcoulombs. (The conversion is ten times the numerical 2speed of light in meters/second.)
- Robert Millikan: The Oil-Drop Experiment
- G. J. Stoney (1894). "Of the "Electron," or Atom of Electricity". Philosophical Magazine. 5. 38: 418–420. doi:10.1080/14786449408620653.
- Apogee CCD University – Pixel Binning
- Q is for Quantum, by John R. Gribbin, Mary Gribbin, Jonathan Gribbin, page 296, Web link
- Loschmidt, J. (1865). "Zur Grösse der Luftmoleküle". Sitzungsberichte der kaiserlichen Akademie der Wissenschaften Wien. 52 (2): 395–413. English translation Archived February 7, 2006, at the Wayback Machine..
- Mohr, Peter J.; Taylor, Barry N.; Newell, David B. (2008). "CODATA Recommended Values of the Fundamental Physical Constants: 2006". Reviews of Modern Physics. 80 (2): 633–730. arXiv: . Bibcode:2008RvMP...80..633M. doi:10.1103/RevModPhys.80.633. Direct link to value..
- Ehl, Rosemary Gene; Ihde, Aaron (1954). "Faraday's Electrochemical Laws and the Determination of Equivalent Weights". Journal of Chemical Education. 31 (May): 226–232. Bibcode:1954JChEd..31..226E. doi:10.1021/ed031p226.
- Mohr, Peter J.; Taylor, Barry N. (1999). "CODATA recommended values of the fundamental physical constants: 1998". Journal of Physical and Chemical Reference Data. 28 (6): 1713–1852. doi:10.1103/RevModPhys.72.351..
- Beenakker, Carlo; Schönenberger, Christian. "Quantum Shot Noise. Fluctuations in the flow of electrons signal the transition from particle to wave behavior". arXiv: ..
- de-Picciotto, R.; Reznikov, M.; Heiblum, M.; Umansky, V.; Bunin, G.; Mahalu, D. (1997). "Direct observation of a fractional charge". Nature. 389 (162–164): 162. Bibcode:1997Natur.389..162D. doi:10.1038/38241..
- Mohr, Peter J.; Newell, David B. (2010). "The physics of fundamental constants". American Journal of Physics. 78 (4): 338–358. Bibcode:2010AmJPh..78..338M. doi:10.1119/1.3279700. p. 356
- Fundamentals of Physics, 7th Ed., Halliday, Robert Resnick, and Jearl Walker. Wiley, 2005 | <urn:uuid:850c3d4b-ef17-4a1c-a6b1-2bd0966c6c5b> | 4.09375 | 2,765 | Knowledge Article | Science & Tech. | 53.154941 | 95,524,757 |
Mass extinctions were followed by periods of low diversity in which certain new species dominated wide regions of the supercontinent Pangaea, reports a new study.
The findings, published in Nature Communications, indicate that mass extinctions may have predictable consequences and provide insights into how biological communities may be expected to change in the future as a result of current high extinction rates.
Mass extinctions are thought to produce ‘disaster faunas’, communities dominated by a small number of widespread species. However, studies to test this theory have been rare and limited in scope, such as being focused on small regions.
The researchers, from the University of Birmingham (UK), North Carolina State University (USA), University of Leeds (UK) and CONICET?Museo Argentino de Ciencias Naturales (Argentina) assessed long-term changes in biodiversity in the supercontinent Pangaea. They analysed changes in nearly 900 animal species between approximately 260 million and 175 million years ago (spanning the late Permian to Early Jurassic). This period witnessed two mass extinctions and the origins of dinosaurs and many modern vertebrate groups.
These extinction events were very important in shaping the evolutionary history of life. The end-Permian event wiped out many of the groups which dominated life on land at the time. By doing so, it freed up ecological niches and allowed new groups to evolve, including the earliest dinosaurs, crocodiles and relatives of mammals and lizards. The end-Triassic event then again wiped-out many major groups, helping to set the stage for the dinosaurs to take over.
The team compared the similarity of animal communities from different regions of the globe based both on which species they shared, and how closely related the species from one region were to those from other regions. This allowed them to calculate the overall similarity of faunas from across the globe through time – the “Biogeographic connectedness”.
David Button, a postdoctoral researcher at North Carolina State University and the resident Brimley Scholar at the NC museum of Natural Sciences said, “These results show that, after both mass extinctions, biological communities not only lost a large number of species, but also became dominated by widespread, newly-evolving species, leading to low diversity across the globe. These common patterns suggest that mass extinctions have predictable influences on animal distributions and may have the potential to guide modern conservation efforts.”
Richard Butler, Professor of Palaeobiology at the University of Birmingham, said, “Mass extinctions were global disasters that fundamentally reshaped ecosystems. Our new analyses provide crucial data that show just how profoundly these cataclysmic events changed and influenced animal distribution.
Martín Ezcurra, Researcher of the Museo Argentino de Ciencias Naturales, said, “The fossil record has the potential to test evolutionary hypotheses in long time spans, which is not possible if evolutionary researches all limited to living plant and animals. This study allows understanding better how macroevolutionary patters developed in the deep time and may help to predict large-scale ecological changes in the short term”.
Due to human activity, we are currently in the sixth mass extinction. There are already concerns that humans are driving global faunas to become more homogenous as a result of landscape simplification, increasing temperatures and introduction of exotic species. This study identifies an additional contributor to this risk, as ongoing biodiversity loss will be expected to result in a “disaster fauna” of more similar species across the globe.
Header Image Credit : Dmitry Bogdanov | <urn:uuid:652cb8ff-e258-4154-9817-bead47684f69> | 4.28125 | 742 | News Article | Science & Tech. | 13.645435 | 95,524,805 |
The Millennium Ecosystem Assessment (2005) drew international attention to the importance of ecosystems in providing goods and services for mankind. Since then a series of assessments at national regional and global level has been published (e.g. TEEB, UK ecosystem assessment) and the conservation of ecosystem services is now part of the CBD ‘Aichi’ targets. This year the International Platform for Biodiversity and Ecosystem Services was established to perform global assessments to support policies. The Netherlands Environmental Assessment Agency (PBL) has a long history in contributing to international environmental assessments, including the MEA, IPCC reports GEO, GBO etc.
For these contributions the IMAGE / GLOBIO modeling framework has been developed enabling the evaluation of environmental scenarios. Recently An ‘Ecosystems Services’ module was added to IMAGE / GLOBIO to be able to include ecosystem services into integrated assessments.
In this presentation I will give a short historical overview, including the development of the concept. I describe how ecosystem services are implemented in the IMAGE GLOBIO framework. And finally show methods to present and summarize the information into relatively simple indicators.
|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:e2dee8b5-e824-4a24-a002-c69c32f3203b> | 2.890625 | 317 | News (Org.) | Science & Tech. | 14.252 | 95,524,819 |
Eingeladen durch Dr. Klaus-Holger Knorr.
Natural peatlands are important sinks for atmospheric C and nutrient and are characterized by a specialized flora and fauna. Peatlands store about 20-40 % of global C bound in soils. This original storage function was lost due to drainage activities for agricultural land-use. In opposite, peatlands appear now as ecosystems polluting atmosphere and surface waters by CO2, CH4, and nutrients. Many species of the flora and fauna typical for wetlands are endangered or extinct regionally. Therefore, a re-wetting of peatlands is an urgent challenge and will be performed in large areas in Northern Germany. The re-establishment of the original ecological functions is a challenging process since strong changes of soil chemistry and soil physics took place during desiccation. In the presentation, problems and management strategies of peatland re-wetting under special consideration of nature conservation and water quality of adjacent surface waters will be discussed.
|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:f5420d3f-ab03-4e98-bb58-30a9bf513485> | 3.828125 | 284 | Product Page | Science & Tech. | 31.462842 | 95,524,820 |
- iOS 10.3+
- tvOS 10.2+
- macOS 10.12+
- Xcode 10.0+Beta
In the Devices and Commands sample, you learned how to write an app that uses Metal and issues basic rendering commands to the GPU.
In this sample, you’ll learn how to render basic geometry in Metal. In particular, you’ll learn how to work with vertex data and SIMD types, configure the graphics rendering pipeline, write GPU functions, and issue draw calls.
The Metal Graphics Rendering Pipeline
The Metal graphics rendering pipeline is made up of multiple graphics processing unit (GPU) stages, some programmable and some fixed, that execute a draw command. Metal defines the inputs, processes, and outputs of the pipeline as a set of rendering commands applied to certain data. In its most basic form, the pipeline receives vertices as input and renders pixels as output. This sample focuses on the three main stages of the pipeline: the vertex function, the rasterization stage, and the fragment function. The vertex function and fragment function are programmable stages. The rasterization stage is fixed.
MTLRender object represents a graphics-rendering pipeline. Many stages of this pipeline can be configured using a
MTLRender object, which defines a large portion of how Metal processes input vertices into rendered output pixels.
A vertex is simply a point in space where two or more lines meet. Typically, vertices are expressed as a collection of Cartesian coordinates that define specific geometry, along with optional data associated with each coordinate.
This sample renders a simple 2D triangle made up of three vertices, with each vertex containing the position and color of a triangle corner.
Position is a required vertex attribute, whereas color is optional. For this sample, the pipeline uses both vertex attributes to render a colored triangle onto a specific region of a drawable.
Use SIMD Data Types
Vertex data is usually loaded from a file that contains 3D model data exported from specialized modeling software. Detailed models may contain thousands of vertices with many attributes, but ultimately they all end up in some form of array that is specially packaged, encoded, and sent to the GPU.
The sample’s triangle defines a 2D position (x, y) and RGBA color (red, green, blue, alpha) for each of its three vertices. This relatively small amount of data is directly hard coded into an array of structures, where each element of the array represents a single vertex. The structure used as the data type for the array elements defines the memory layout of each vertex.
Vertex data, and 3D graphics data in general, is usually defined with vector data types, simplifying common graphics algorithms and GPU processing. This sample uses optimized vector data types provided by the SIMD library to represent the triangle’s vertices. The SIMD library is independent from Metal and MetalKit, but is highly recommended for developing Metal apps, mainly for its convenience and performance benefits.
The triangle’s 2D position components are jointly represented with a
vector SIMD data type, which holds two 32-bit floating-point values. Similarly, the triangle’s RGBA color components are jointly represented with a
vector SIMD data type, which holds four 32-bit floating-point values. Both of these attributes are then combined into a single
The triangle’s three vertices are directly hard coded into an array of
AAPLVertex elements, thus defining the exact attribute values of each vertex.
Set a Viewport
A viewport specifies the area of a drawable that Metal renders content to. A viewport is a 3D area with an x and y offset, a width and height, and near and far planes (although these last two aren’t needed here because this sample renders 2D content only).
Assigning a custom viewport for the pipeline requires encoding a
MTLViewport structure into a render command encoder by calling the
set method. If a viewport isn’t specified, Metal sets a default viewport with the same size as the drawable used to create the render command encoder.
Write a Vertex Function
The main task of a vertex function (also known as a vertex shader) is to process incoming vertex data and map each vertex to a position in the viewport. This way, subsequent stages in the pipeline can refer to this viewport position and render pixels to an exact location in the drawable. The vertex function accomplishes this task by translating arbitrary vertex coordinates into normalized device coordinates, also known as clip-space coordinates.
Clip space is a 2D coordinate system that maps the viewport area to a [-1.0, 1.0] range along both the x and y axes. The viewport’s lower-left corner is mapped to (-1.0, -1.0), the upper-right corner is mapped to (1.0, 1.0), and the center is mapped to (0.0, 0.0).
A vertex function executes once for each vertex drawn. In this sample, for each frame, three vertices are drawn to make up a triangle. Thus, the vertex function executes three times per frame.
Vertex functions are written in the Metal shading language, which is based on C++ 14. Metal shading language code may seem similar to traditional C/C++ code, but the two are fundamentally different. Traditional C/C++ code is typically executed on the CPU, whereas Metal shading language code is exclusively executed on the GPU. The GPU offers much larger processing bandwidth and can work, in parallel, on a larger number of vertices and fragments. However, it has less memory than a CPU, does not handle control flow operations as efficiently, and generally has higher latency.
The vertex function in this sample is called
vertex and this is its signature.
Declare Vertex Function Parameters
The first parameter,
vertex, uses the
[[vertex attribute qualifier and holds the index of the vertex currently being executed. When a draw call uses this vertex function, this value begins at 0 and is incremented for each invocation of the
vertex function. A parameter using the
[[vertex attribute qualifier is typically used to index into an array that contains vertices.
The second parameter,
vertices, is the array that contains vertices, with each vertex defined as an
AAPLVertex data type. A pointer to this structure defines an array of these vertices.
The third and final parameter,
viewport, contains the size of the viewport and has a
vector data type.
viewport parameters use SIMD data types, which are types understood by both C and Metal shading language code. The sample can thus define the
AAPLVertex structure in the shared
AAPLShader header, included in both the
AAPLShaders code. Therefore, the shared header ensures that the data type of the triangle’s vertices is the same in the Objective-C declaration (
triangle) as it is in the Metal shading language declaration (
vertices). Using SIMD data types in your Metal app ensures that memory layouts match exactly across CPU/GPU declarations and facilitates sending vertex data from the CPU to the GPU.
viewport parameters use the
[[buffer(index)]] attribute qualifier. The values of
AAPLVertex are the indices used to identify and set the inputs to the vertex function in both the
Declare Vertex Function Return Values
Rasterizer structure defines the return value of the vertex function.
Vertex functions must return a clip-space position value for each vertex via the
[[position]] attribute qualifier, which the
clip member uses. When this attribute is declared, the next stage of the pipeline, rasterization, uses the
clip values to identify the position of the triangle’s corners and determine which pixels to render.
Process Vertex Data
The body of the sample’s vertex function does two things to the input vertices:
Performs coordinate-system transformations, writing the resulting vertex clip-space position to the
.clip Space Position
Passes the vertex color to the
To get an input vertex, the
vertex parameter is used to index into the
This sample obtains a 2D vertex coordinate from the
position member of each
vertices element and converts it into a clip-space position written to the
out return value. Each vertex input position is defined relative to the number of pixels in the x and y directions from the center of the viewport. Thus, to convert these pixel-space positions to clip-space positions, the vertex function divides by half the viewport size.
Finally, the vertex function accesses the
color member of each
vertices element and passes it along to the
out return value, without performing any modifications.
The contents of the
Rasterizer return value are now complete, and the structure is passed along to the next stage in the pipeline.
After the vertex function executes three times, once for each of the triangle’s vertices, the next stage in the pipeline, rasterization, begins.
Rasterization is the stage in which the pipeline’s rasterizer unit produces fragments. A fragment contains raw prepixel data that’s used to produce the pixels rendered to a drawable. For each complete triangle produced by the vertex function, the rasterizer determines which pixels of the destination drawable are covered by the triangle. It does so by testing whether the center of each pixel in the drawable is the inside the triangle. In the following diagram, only fragments whose pixel center is inside the triangle are produced. These fragments are shown as gray squares.
Rasterization also determines the values that are sent to the next stage in the pipeline: the fragment function. Earlier in the pipeline, the vertex function output the values of a
Rasterizer structure, which contains a clip-space position (
clip) and a color (
clip member uses the required
[[position]] attribute qualifier, indicating that these values are directly used to determine the triangle’s fragment coverage area. The
color member doesn’t have an attribute qualifier, indicating that these values should be interpolated across the triangle’s fragments.
The rasterizer passes
color values to the fragment function after converting them from per-vertex values to per-fragment values. This conversion uses a fixed interpolation function, which calculates a single weighted color derived from the
color values of the triangle’s three vertices. The weights for the interpolation function (also known as barycentric coordinates.) are the relative distances of each vertex position to the center of a fragment. For example:
If a fragment is exactly in the middle of a triangle, equidistant from each of the triangle’s three vertices, the color of each vertex is weighted by 1/3. In the following diagram, this is shown as the gray fragment (0.33, 0.33, 0.33) in the center of the triangle.
If a fragment is very close to one vertex and very far from the other two, the color of the close vertex is weighted toward 1 and the color of the far ones is weighted toward 0. In the following diagram, this is shown as the reddish fragment (0.5, 0.25, 0.25) near the bottom-right corner of the triangle.
If a fragment is on an edge of the triangle, midway between two of the three vertices, the color of each edge-defining vertex is weighted by 1/2 and the color of the nonedge vertex is weighted by 0. In the following diagram, this is shown as the cyan fragment (0.0, 0.5, 0.5) on the left edge of the triangle.
Because rasterization is a fixed pipeline stage, its behavior can’t be modified by custom Metal shading language code. After the rasterizer creates a fragment, along with its associated values, the results are passed along to the next stage in the pipeline.
Write a Fragment Function
The main task of a fragment function (also known as fragment shader) is to process incoming fragment data and calculate a color value for the drawable’s pixels.
The fragment function in this sample is called
fragment and this is its signature.
The function has a single parameter,
in, that uses the same
Rasterizer structure returned by the vertex function. The
[[stage attribute qualifier indicates that this parameter comes from the rasterizer. The function returns a four-component floating-point vector, which contains the final RGBA color value to be rendered to the drawable.
This sample demonstrates a very simple fragment function that returns the interpolated
color value from the rasterizer, without further processing. Each fragment renders its interpolated
color value to its corresponding pixel in the triangle.
Obtain Function Libraries and Create a Pipeline
When building the sample, Xcode compiles the
AAPLShaders file along with the Objective-C code. However, Xcode can’t link the
fragment functions at build time; instead, the app needs to explicitly link these functions at runtime.
Metal shading language code is compiled in two stages:
Front-end compilation happens in Xcode at build time.
.metalfiles are compiled from high-level source code into intermediate representation (IR) files.
Back-end compilation happens in a physical device at runtime. IR files are then compiled into low-level machine code.
Each GPU family has a different instruction set. As a result, Metal shading language code can only be fully compiled into native GPU code at runtime, by the physical device itself. Front-end compilation reduces some of this compilation overhead by storing IR in a
default file that’s packaged inside the sample’s
default file is a library of Metal shading language functions that’s represented by a
MTLLibrary object retrieved at runtime by calling the
new method. From this library, specific functions represented by
MTLFunction objects can be retrieved.
MTLFunction objects are used to create a
MTLRender object that represents the graphics-rendering pipeline. Calling the
new method of a
MTLDevice object begins the back-end compilation process that links the
fragment functions, resulting in a fully compiled pipeline.
MTLRender object contains additional pipeline settings that are configured by a
MTLRender object. Besides the vertex and fragment functions, this sample also configures the
pixel value of the first entry in the
color array. This sample only renders to a single target, the view’s drawable (
color), whose pixel format is configured by the view itself (
color). A view’s pixel format defines the memory layout of each of its pixels; Metal must be able to reference this layout when creating the pipeline so that it can properly render the color values produced by the fragment function.
Send Vertex Data to a Vertex Function
After the pipeline is created, it can be assigned to a render command encoder. This operation that all subsequent rendering commands will be processed by that specific pipeline.
This sample uses the
set method to send vertex data to a vertex function. As mentioned earlier, the signature of the sample’s
vertex function has two parameters,
viewport, that use the
[[buffer(index)]] attribute qualifier. The value of the
index parameter in the
set method maps to the parameter with the same
index value in the
[[buffer(index)]] attribute qualifier. Thus, calling the
set method sets specific vertex data for a specific vertex function parameter.
AAPLVertex values are defined in the
AAPLShader header shared between the
AAPLShaders files. The sample uses these values for the
index parameter of both the
set method and the
[[buffer(index)]] attribute qualifier corresponding to the same vertex function. Sharing these values across different files makes the sample more robust by reducing potential index mismatches due to hard-coded integers (which could send the wrong data to the wrong parameter).
This sample sends the following vertex data to a vertex function:
trianglepointer is sent to the
verticesparameter, using the
Input Index Vertices
_viewportpointer is sent to
viewportparameter, using the
Input Index Viewport Size
Draw the Triangle
After setting a pipeline and its associated vertex data, issuing a draw call executes the pipeline and draws the sample’s single triangle. The sample encodes a single drawing command into the render command encoder.
Triangles are geometric primitives in Metal that require three vertices to be drawn. Other primitives include lines that require two vertices, or points that require just one vertex. The
draw method lets you specify exactly what type of primitive to draw and which vertices, derived from the previously set vertex data, to use. Setting 0 for the
vertex parameter indicates that drawing should begin with the first vertex in the array of vertices. This means that the first value of the vertex function’s
vertex parameter, which uses the
[[vertex attribute qualifier, will be 0. Setting 3 for the
vertex parameter indicates that three vertices should be drawn, producing a single triangle. (That is, the vertex function is executed three times with values of 0, 1, and 2 for the
This call is the last call needed to encode the rendering commands for a single triangle. With the drawing complete, the render loop can end encoding, commit the command buffer, and present the drawable containing the rendered triangle.
In this sample, you learned how to render basic geometry in Metal.
In the Basic Buffers sample, you’ll learn how to use a vertex buffer to improve your rendering efficiency. | <urn:uuid:10f9e15d-f70d-4e7a-8123-14a2d5873756> | 3.25 | 3,739 | Tutorial | Software Dev. | 41.0412 | 95,524,823 |
Who has, or has not, heard of "cloud to ground lightning"?
All of the years that I lived in New Jersey (about 30) I had never heard of it - until I moved down south. Now, that is about all that we get - and it is deadly.
Cloud to ground lightning is just one type of the electrical phenomenon most people group together and simply call lightning. When the electrical current leaves a cloud and makes contact with the ground, that's cloud to ground lightning - what most people would call a strike or lightning strike. These strikes hit trees, buildings, people, etc. So yes, the answer is that they are dangerous.
I know what it is - now. I just do not like it. For 30 years up in the nortern state I heard about trees occasionally hit by "lightning". Now in 4-5 years in the southern state I have heard about so many "people" killed by cloud-to-ground lightning!
Lightning strikes the ground, the air, or inside clouds. There are roughly 5 to 10 times as many cloud flashes as there are cloud-to-ground flashes.
There are two types of ground flashes: natural (those that occur because of normal electrification in the environment), and artificially initiated or triggered. Artificially initiated lightning includes strikes to very tall structures, airplanes, rockets and towers on mountains. Triggered lightning goes from ground to cloud, while “natural” lightning is cloud to ground.
In cloud-to-ground lightning (CG), a channel of negative charge, called a stepped leader, will zigzag downward in roughly 50-yard segments in a forked pattern. This stepped leader is invisible to the human eye, and shoots to the ground in less time than it takes to blink. As it nears the ground, the negatively charged stepped leader is attracted to a channel of positive charge reaching up, a streamer, normally through something tall, such as a tree, house, or telephone pole. When the oppositely-charged leader and streamer connect, a powerful electrical current begins flowing. A return stroke of bright luminosity travels about 60,000 miles per second back towards the cloud. A flash consists of one or perhaps as many as 20 return strokes. We see lightning flicker when the process rapidly repeats itself several times along the same path. The actual diameter of a lightning channel is one-to two inches.
When I lived in NJ all the weatherman said was "Thuderstorms today". Now it is "Severe T-storms with critical cloud-to-ground lightning". After the storms you hear about all of the people who were hit by the lightning. I never heard it this bad.
by Claire Evans 5 years ago
This picture of the Vatican being struck by lightening was taken just after Pope Benedict resigned. It has disturbed even non-religious people. Luke 10:18Jesus replied, "I saw Satan fall like lightning from heaven.Say same the Pope's resignation is a Saint Malachy prophecy...
by Ana Maria Orantes 7 days ago
A house or building is the best shelter to prevent getting hurt while lightning is going on. You never go under a tree. These days cars are so well equipped with protection against lightning that will be a second choice. Good luck to everyone while trying to stay safe. I am looking...
by Romel Tarroza 5 years ago
Lightning strikes Vatican after Pope Benedict resigns, What does that mean?A lightning strikes St Peter's dome at the Vatican an Hours after Pope Benedict XVI announced that he will resign as leader of the Catholic Church. What do you think is the meaning of that lightning?
by Ghillie0Sniper 6 years ago
Have you heard of First Strike Paintball?If so, do you think there is now such thing as a true paintball sniper?
by Spitfire07 6 years ago
Have you ever seen lightning in a snow storm? Is it possible?
by backporchstories 6 years ago
What is the best thing to do in an electrical storm?
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Encapsulation and Testability
Encapsulation and Testability
In this article, an Agile development guru explains how the different kinds of testing function in an Agile environment, and the importance of encapsulated code.
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Poorly encapsulated software is hard to test because without clear boundaries, what we actually test becomes significantly larger than what we need to test. This makes our tests run slower and it also makes them brittle so our tests are harder to maintain.
When code is unencapsulated, it can be hard to lock down behaviors in a system that we want to test. This can get so bad that we may not even be able to use a programmatic interface and must resort instead to simulating the user interacting with the system.
Manual testing or even automating user input to drive testing is a bad idea. It's far too high level and it ties your tests to your user interface, making them brittle. It's far better to provide a programmatic interface that can be used to test code.
Unit testing is the first type of testing we should think of because it's the simplest and also the most cost-effective.
Find problems early, or better yet, set up the system so we just can't make mistakes. Encapsulation is like that. Encapsulation is a promise that a boundary is created and that nothing will penetrate that boundary. We can define an object that has public parts and private parts. The public parts can be accessed by anything or anyone but the private parts are internal, nothing on the outside can access the private information or behavior inside.
This guarantee in software languages allows us to create software that is both reliable and secure. Of course, by convention, instance data that an object holds should be marked private so that no other object can access it directly. If outside objects do need access to that data then we will provide public getters and setters.
We may, for example, want to serialize access to a particular resource so we're granting access to only one request at a time, or we may want to just keep track of the requestors, or keep account of them, or whatever. The object that holds the state gets to decide - and that's the point of object-oriented programming. We want objects to encapsulate their own state and be in charge of it, that is to say, to contain the behaviors that access that state, which is the next code quality that we'll be talking about: assertiveness.
Testable code tends to be well-encapsulated. It hides implementation details and can validate if that behavior is correct. Testable code is code that can be tested at the unit level. When code is built with tests in this way there's less need for other kinds of tests. A lot of the QA testing, scenario testing, and other types of non-automated testing can go away. We're then left with a suite of tests that have all the characteristics we need: they run fast, they give the right level of feedback, and they support refactoring - all good qualities in a test base.
Unit tests run fast because we're only testing what we need to. If the tests were written well and written to be unique, unit tests also provide the right level of feedback.
And finally, when they're written to test behaviors rather than implementations, unit tests support refactoring. If we test behaviors and then refactor the code so we're changing the design but not changing the behaviors our tests shouldn't break.
Published at DZone with permission of David Bernstein , DZone MVB. See the original article here.
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Nine hundred scientists will be meeting in Heidelberg between 15 and 20 July 2013 for one of the biggest astronomical conferences anywhere in the world. On these six days, the experts intend to exchange views and knowledge about the present state of research on the evolution of stars and planets.
They will also be discussing the development of future strategies that might lead to the discovery of a second Earth. This major international event entitled “Protostars & Planets” last took place on Hawaii in 2005. After years of planning it will now be organised jointly by the Centre for Astronomy of Heidelberg University and the Max Planck Institute for Astronomy (Heidelberg).
In astronomical research, planets like Earth are referred to as “seed corns of the Universe” because life can evolve and develop on them. On this point researchers are largely in agreement. But the question of how stars and their planetary systems can form and evolve in the first place and how planets capable of supporting life can be identified is at present one of the most exciting and spectacular research areas in astronomy and astrophysics.
“Knowledge here is progressing at such a rate that scientists working in this area meet regularly at a special international conference to obtain an overview of the state of research, cultivate connectivity and receive new impulses for their work”, says Prof. Dr. Cornelis Dullemond of the Centre for Astronomy of Heidelberg University. The results of the scientific exchange in Heidelberg are to be ploughed into a publication of over 1,000 pages that will function as the standard work on research in this area for the years to come. The upcoming sixth “Protostars & Planets” conference will be the first to take place outside the United States.
The programme of the conference and other relevant information can be found at http://www.ppvi.org.
Invitation to the press conference
Initial important results from the conference will be communicated at a question-and-answer session for the press at 12.30 to 2.30 pm on Wednesday, 17 July 2013, in the Robert Schumann Room (1st floor) of the Kongresshaus Stadthalle conference centre, Neckarstaden 24, in Heidelberg. Renowned international scientists will be on hand to answer questions about the evolution of stars and planets or the discovery and features of inhabitable planets. They includeProf. Dr. John Bally (University of Colorado at Boulder / USA)
Note for newsdesks
The location of the conference from 15 to 20 July 2013 is the Kongresshaus Stadthalle, Neckarstaden 24, in Heidelberg. Members of the press will have the opportunity of establishing contact with individual researchers and interviewing them on selected topics. Filming and documentation are also possible. Liaison support in establishing contact and coordinating appointment dates is provided by Dr. Markus Poessel of the Haus der Astronomie (literally House of Astronomy) and Dr. Guido Thimm of the Centre for Astronomy of Heidelberg University.
ContactDr. Markus Poessel
Marietta Fuhrmann-Koch | idw
Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine
13.07.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
Conference on Laser Polishing – LaP: Fine Tuning for Surfaces
12.07.2018 | Fraunhofer-Institut für Lasertechnik ILT
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
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18.07.2018 | Health and Medicine | <urn:uuid:65ee8344-26ec-41ea-8b7b-8d3427cb81de> | 2.828125 | 1,319 | Content Listing | Science & Tech. | 39.637641 | 95,524,874 |
American engineers believe that the thermal energy of the Earth, which is released into the environment, can be used as a renewable energy source for electricity production in some areas of the planet.
The new technique, developed by Federico Capasso and his colleagues at Harvard University (USA), allows to produce electricity from the heat radiated by Earth into the environment. The experts came up with this idea when they discovered that the planet is “heating” space with a capacity of 100 million gigawatts.
At present there are no technologies to extract electricity from the heat of the Earth. The authors of this study created a special scheme of “thermal batteries”, focusing on the data on heat flux emanating from the Earth. These data were collected by specialists in the town of Lamont (Oklahoma).
This device includes a set of special antennas and connecting electrical circuits. They are set up in such a way that they interact with the long-wavelength infrared radiation when a current passes through them.
The device is similar to the induction loops that are used in e-tickets, as well as in “wireless” chargers for mobile phones.
At the moment, as the experts say, there are no such antennas in practice. However, the results of calculations and simulations demonstrate the feasibility of such “thermal” generators. However, the authors of the study emphasize that their efficiency will initially be very low.
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The conclusion must be that there is no support for the previous theory regarding compensatory mechanisms in non-carriers of the T allele. Instead the new findings indicate that the KIBRA gene plays a role in memory by improving the hippocampus function in carriers of the T allele.
In a study published in Science in 2006 the entire genome was screened (in a so-called Genome-wide association study) for genetic variations of importance to episodic memory (Papassotiropoulos et al., 2006). Individuals who carried the T allele (CT or TT genotype) in a common C/T polymorphism in the KIBRA gene had better episodic memory than non-carriers of the T allele (CC genotype). In the same study, brain activity was examined during a memory task in 30 subjects with the help of a magnetic camera (fMRI). It was found that non-carriers of the T allele had greater activation of the hippocampus, an area in the brain that is important for episodic memory, than did T carriers.
Since the groups had the same memory performance, the results were explained as indicating that non-carriers needed to compensate for their poorer memory function with increased activation of the hippocampus in order to reach the same level of performance as T carriers. Increased activation in the hippocampus is strongly associated with positive aspects of the memory function, and with other genes related to memory the opposite has been observed: increased hippocampus activation in carriers of a gene variant that is associated with better memory (e.g. Hariri et al., 2003). In those cases a reasonable explanation has been that the gene is important for memory via a favorable effect on the hippocampus function.Improved memory performance in carriers of the KIBRA T allele has been verified in several subsequent studies (e.g. Bates et. al., 2009, Preuschhof et al., 2010), but since the 2006 Science article, this is the first to study KIBRA in relation to brain activation.
For more information, please contact Karolina Kauppi email@example.com , phone: +46 (0)90-786 51 86, ext. 13, mobile: +46 (0)730-43 38 26
Bertil Born | idw
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....
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In a new study published in the journal Icarus, Nathan argues that astronomers don’t have as good a handle on the size and other physical characteristics of asteroids as they previously thought.
In particular, Nathan identifies major flaws in the methods used by the NASA-funded NEOWISE project—a mission that analyzed data on some 164,000 asteroids observed by the WISE space telescope—and demonstrates that many of the asteroid diameter estimates and other results published by the project are irreproducible and significantly less accurate than claimed. The new study is the first independent analysis to critically examine those results and the scientific methods used by the NEOWISE project, which was led by a team at the Caltech Jet Propulsion Lab.
The Icarus article is an update of work Nathan published in preprint form in May 2016 on arXiv.org, and his latest findings have drawn coverage in the New York Times. Learn more background on the research and why it matters on Medium and in Retraction Watch, or read the full study. | <urn:uuid:6b5940fd-d7d7-40cf-9e80-c954d6e60286> | 3.109375 | 210 | News (Org.) | Science & Tech. | 28.818262 | 95,524,935 |
The innovation opens up new possibilities for studying fish behaviour and group dynamics, which provides useful information to support freshwater and marine environmental management, to predict fish migration routes and assess the likely impact of human intervention on fish populations.
"We've proven it's possible to use robotic fish to study relationships between individuals and shoal dynamics as well as the behaviour of individual fish," says PhD student Jolyon Faria who led the experiments. "In the past, we had to watch a shoal and change environmental conditions to see how that affected behaviour. Because the robotic fish is accepted by the shoal, we can use it to control one or several individuals, which allows us to study quite complex situations such as aggressive, cooperative, anti-predator and parental behaviour."
The computer controlled replica - dubbed Robofish by its creators John Dyer, Dr Dean Waters and Natalie Holt - is a plaster cast model of a three-spined stickleback with an acetate fin, painted to mimic the coloration and markings of a real fish. The scientists needed to prove that Robofish was accepted into the group sufficiently for the fish to respond to the robot like a normal shoal member.
"Although Robofish looked like a stickleback to us, we weren't sure whether the other fish would see it in the same light," explained Jolyon. "We also thought there might be a problem with the smell, as fish use chemical cues in the water to identify other shoal members. In the end, Robofish was accepted straight away - though we did trial various models until we found one that worked the best."
Robofish was placed in a tank with either single fish or a group of ten, and then programmed to follow a set path at a slightly faster speed than normal fish. The aim was to see if Robofish could tempt other fish to leave the tank's refuge area and convince its companions to make a 90 degree turn.
Single fish left the refuge much sooner if Robofish instigated the move than they would on their own, though groups of fish left quite quickly without other motivation. Robofish was able to persuade both single fish and groups to make a turn. However, the longer time the fish spent in the tank, the less likely they were to display shoaling activity either on their own or in response to Robofish.
"Because Robofish moved faster and without stopping and tended to be at the front or on the edge of the shoal, the other fish saw it as bold and definite in its actions, which encouraged them to follow," said Jolyon. "The fish were more easily influenced by a bolder member when they were nervous in new surroundings. Once they'd got used to the tank, they moved round quite happily to explore the tank, rather than moving in unison as they did at the start."
The experiments - funded through the Biotechnology and Biological Sciences Research Council and the Engineering and Physical Sciences Research Council - have also allowed the researchers to answer a long-standing question of group dynamics: whether an individual's ability to influence a group is dependent on how close together its members are. In fact, when Robofish turned, its nearest neighbour did turn first, but it made no difference whether they were 9cm or 33cm away from the robot. Most models of group dynamics are based on the assumption that the closer you are to your neighbour the more influence you have, but this study has added weight to the argument that relative, rather than metric distance, is more important.
Ioannis Delis, Physiological Society (Jul 2018), £10,000
Scott Bowen, Physiological Society (Jul 2018), £10,000
Steve Clapcote, Jamie Johnston, The Dunhill Medical Trust (Jun 2018), £254,874
Adrian Goldman, MRC (Jun 2018), £98,627
Darren Tomlinson, Michelle Peckham, Megan Wright, BBSRC (Jun 2018), £150,443
Simon Walker, Royal Society (Jun 2018), £337,601
Tom Thirkell, N8 Agrifood (Jun 2018), £14,870
Stephen Muench with Glaxo SmithKline & UCB Celltech, BBSRC Industrial Partnership Award (Apr 2018), £480,225
Steve Clapcote, BBSRC (Apr 2018), £443,072
Helen Miller, Innovate UK (Apr 2018), £999,960
Elisabetta Groppelli, David Rowlands & Stanley Lemon (University of North Carolina), Medical Research Foundation Fellowship (Apr 2018), £293,494
Nikesh Patel, Medical Research Foundation fellowship (Apr 2018), £290,976
Graham Askew with colleagues in Hull and Liverpool, BBSRC (Apr 2018), £150,498
Andrew Macdonald, Neil Ranson & Richard Foster, Kidney Research UK (Apr 2018), £82,821
Jessica Kwok & Ralf Richter, Leverhulme Trust (Apr 2018), £298,273
Julie Aspden, Royal Society (Apr 2018), £20,000
Liz Duncan, Royal Society (Mar 2018), £14,602
Alex O'Neill & Ryan Seipke, BBSRC (Feb 2018), £45,489
Jim Deuchars, Royal Society (Feb 2018), £16,300
Stefan Kepinski & Netta Cohen, Leverhulme Trust (Feb 2018), £320,387
Lisa Collins, BBSRC (Feb 2018), £49,950
Alison Baker, BBSRC (Feb 2018), £30,000
Nikita Gamper, BBSRC (Feb 2018), £30,000
Lars Jeuken, BBSRC (Feb 2018), £30,000
Scott Bowen, Leducq Foundation Grant (Feb 2018), £28,470
Jessica Kwok and Ronaldo Ichiyama, International Spinal Research Trust (Feb 2018), £94,450
Alex O'Neill, Oxford Drug Design (Jan 2018), £86,098
Dave Lewis and Colleagues in South Africa, HEFCE Global Challenge Research (Jan 2018), £48,000
Sarah Calaghan, Ed White, John Colyer, Isuru Jayasinghe, BHF (Jan 2018), £128,308
Christine Foyer and Alison Baker, HEFCE GCRF Grant (Jan 2018), £71,158
Alison Baker, Yun Yung Gong and Lindsay Stringer and ICRISAT India, HEFCE GCRF Grant (Jan 2018), £27,000
Graham Askew, Simon Walker, BBSRC (Jan 2018), £699,781
Jennifer Tomlinson, Royal Society (Jan 2018), £512,801
Alison Dunn, NERC (Dec 2017), £18,000
Jennifer Tomlinson, Royal Society-Research Fellows Enhancement Award (Dec 2017), £94,681
Helen Miller, AB AGri Grant (Dec 2017), £73,600
Simon Walker, Royal Society Enhancement Award (Dec 2017), £10,000
Carrie Ferguson, Bryan Taylor, Harry Rossiter, The Physiological Society (Dec 2017), £7,392
Ralf Richter, Royal Society (Dec 2017), £6,000
Christine Foyer, British Council Newton Fund (Dec 2017), £49,840
Adrian Whitehouse and colleagues in School of Chemistry and University of Liverpool, MRC (Nov 2017), £622,319
Michelle Peckham, Neil Ransom, MRC (Nov 2017), £495,159
Dave Lewis, British Council India (Nov 2017), £22,540
Elton Zeqiraj, Royal Society (Nov 2017), £15,000
Hannah Dugdale, Royal Society (Nov 2017), £15,000
Shaunna Burke, Cancer Research UK Innovation Grant (Nov 2017), £20,000
Alex O'Neill and colleagues in Chemistry, BBSRC (Nov 2017), £431,865
Jessica Kwok, Wings for Life (Nov 2017), £87,365
Tom Bennett, BBSRC (Oct 2017), £523,679
Neil Ranson, Darren Tomlinson, BBSRC (Oct 2017), £494,318
Nikita Gamper, BBSRC (Oct 2017), £490,426
Amanda Bretman and colleagues from UEA, NERC (Oct 2017), £430,886
Juan Fontana, Rosetrees Trust consumables grant (Oct 2017), £22,500
Helen Miller, DSM Nutritional Products AG (Sep 2017), £69,988
Neil Ranson, Juan Fontana, Mark Harris, Michelle Peckham, Ralf Richter, Peter Stockley, Patricija Van Oosten-Hawle and colleagues in Engineering, FMH and MAPS, Wellcome Trust Equipment Call (Sep 2017), £418,000
Jamie Johnston, Physiological Society (Sep 2017), £10,000
Frank Sobott, Adrian Goldman, Mark Harris, Andrew Macdonald, Stephen Muench, Sheena Radford and colleagues in FMH and MAPS, Wellcome Trust Equipment Call (Aug 2017), £415,000 | <urn:uuid:b2764250-3376-4015-917a-054f1bc3bd1d> | 4 | 1,921 | Knowledge Article | Science & Tech. | 21.44835 | 95,524,948 |
Ray tracing (physics)
In physics, ray tracing is a method for calculating the path of waves or particles through a system with regions of varying propagation velocity, absorption characteristics, and reflecting surfaces. Under these circumstances, wavefronts may bend, change direction, or reflect off surfaces, complicating analysis. Ray tracing solves the problem by repeatedly advancing idealized narrow beams called rays through the medium by discrete amounts. Simple problems can be analyzed by propagating a few rays using simple mathematics. More detailed analysis can be performed by using a computer to propagate many rays.
When applied to problems of electromagnetic radiation, ray tracing often relies on approximate solutions to Maxwell's equations that are valid as long as the light waves propagate through and around objects whose dimensions are much greater than the light's wavelength. Ray theory does not describe phenomena such as interference and diffraction, which require wave theory (involving the phase of the wave).
Ray tracing works by assuming that the particle or wave can be modeled as a large number of very narrow beams (rays), and that there exists some distance, possibly very small, over which such a ray is locally straight. The ray tracer will advance the ray over his distance, and then use a local derivative of the medium to calculate the ray's new direction. From this location, a new ray is sent out and the process is repeated until a complete path is generated. If the simulation includes solid objects, the ray may be tested for intersection with them at each step, making adjustments to the ray's direction if a collision is found. Other properties of the ray may be altered as the simulation advances as well, such as intensity, wavelength, or polarization. The process is repeated with as many rays as are necessary to understand the behavior of the system.
One particular form of ray tracing is radio signal ray tracing, which traces radio signals, modeled as rays, through the ionosphere where they are refracted and/or reflected back to the Earth. This form of ray tracing involves the integration of differential equations that describe the propagation of electromagnetic waves through dispersive and anisotropic media such as the ionosphere. An example of physics-based radio signal ray tracing is shown to the right. Radio communicators use ray tracing to help determine the precise behavior of radio signals as they propagate through the ionosphere.
The image at the right illustrates the complexity of the situation. Unlike optical ray tracing where the medium between objects typically has a constant refractive index, signal ray tracing must deal with the complexities of a spatially varying refractive index, where changes in ionospheric electron densities influence the refractive index and hence, ray trajectories. Two sets of signals are broadcast at two different elevation angles. When the main signal penetrates into the ionosphere, the magnetic field splits the signal into two component waves which are separately ray traced through the ionosphere. The ordinary wave (red) component follows a path completely independent of the extraordinary wave (green) component.
Sound velocity in the ocean varies with depth due to changes in density and temperature, reaching a local minimum near a depth of 800–1000 meters. This local minimum, called the SOFAR channel, acts as a waveguide, as sound tends to bend towards it. Ray tracing may be used to calculate the path of sound through the ocean up to very large distances, incorporating the effects of the SOFAR channel, as well as reflections and refractions off the ocean surface and bottom. From this, locations of high and low signal intensity may be computed, which are useful in the fields of ocean acoustics, underwater acoustic communication, and acoustic thermometry.
Ray tracing may be used in the design of lenses and optical systems, such as in cameras, microscopes, telescopes, and binoculars, and its application in this field dates back to the 1900s. Geometric ray tracing is used to describe the propagation of light rays through a lens system or optical instrument, allowing the image-forming properties of the system to be modeled. The following effects can be integrated into a ray tracer in a straightforward fashion:
- Dispersion leads to chromatic aberration
- Laser light effects
- Thin film interference (optical coating, soap bubble) can be used to calculate the reflectivity of a surface.
For the application of lens design, two special cases of wave interference are important to account for. In a focal point, rays from a point light source meet again and may constructively or destructively interfere with each other. Within a very small region near this point, incoming light may be approximated by plane waves which inherit their direction from the rays. The optical path length from the light source is used to compute the phase. The derivative of the position of the ray in the focal region on the source position is used to obtain the width of the ray, and from that the amplitude of the plane wave. The result is the point spread function, whose Fourier transform is the optical transfer function. From this, the Strehl ratio can also be calculated.
The other special case to consider is that of the interference of wavefronts, which, as stated before, are approximated as planes. When the rays come close together or even cross, however, the wavefront approximation breaks down. Interference of spherical waves is usually not combined with ray tracing, thus diffraction at an aperture cannot be calculated. However these limitations can be resolved by an advanced modeling technique called Field Tracing. Field Tracing is a modelling technique, combining geometric optics with physical optics enabling to overcome the limitations of interference and diffraction in designing.
The ray tracing techniques are used to optimize the design of the instrument by minimizing aberrations, for photography, and for longer wavelength applications such as designing microwave or even radio systems, and for shorter wavelengths, such as ultraviolet and X-ray optics.
Before the advent of the computer, ray tracing calculations were performed by hand using trigonometry and logarithmic tables. The optical formulas of many classic photographic lenses were optimized by roomfuls of people, each of whom handled a small part of the large calculation. Now they are worked out in optical design software. A simple version of ray tracing known as ray transfer matrix analysis is often used in the design of optical resonators used in lasers. The basic principles of the most frequently used algorithm could be found in Spencer and Murty's fundamental paper: "General ray tracing Procedure".
In seismology, geophysicists use ray tracing to aid in earthquake location and tomographic reconstruction of the Earth's interior. Seismic wave velocity varies within and beneath Earth's crust, causing these waves to bend and reflect. Ray tracing may be used to compute paths through a geophysical model, following them back to their source, such as an earthquake, or deducing the properties of the intervening material. In particular, the discovery of the seismic shadow zone (illustrated at right) allowed scientists to deduce the presence of Earth's molten core.
Energy transport and the propagation of waves plays an important role in the wave heating of plasmas. Power-flow trajectories of electromagnetic waves through a spatially nonuniform plasma can be computed using direct solutions of Maxwell's equations. Another way of computing the propagation of waves in the plasma medium is by using Ray tracing method. Studies of wave propagation in plasmas using ray tracing method can be found in.
- Atmospheric refraction
- Field tracing
- Gradient index optics
- List of ray tracing software
- Ocean acoustic tomography
- Ray tracing (graphics)
- Ray transfer matrix analysis
- G. H. Spencer and M. V. R.K. Murty (1962). "General ray tracing Procedure" (PDF). J. Opt. Soc. Am. 52 (6): 672–678. doi:10.1364/JOSA.52.000672.
- Rawlinson, N., Hauser, J. and Sambridge, M., 2007. Seismic ray tracing and wavefront tracking in laterally heterogeneous media. Advances in Geophysics, 49. 203–267.
- Cerveny, V. (2001). Seismic Ray Theory. ISBN 0-521-36671-2.
- Purdue University
- Bhaskar Chaudhury and Shashank Chaturvedi (2006). "Comparison of wave propagation studies in plasmas using three-dimensional finite-difference time-domain and ray-tracing methods". Physics of Plasmas. 13 (12): 123302. Bibcode:2006PhPl...13l3302C. doi:10.1063/1.2397582.
- Daniel Kuchelmeister, Thomas Müller, Marco Ament, Günter Wunner, Daniel Weiskopf (2012). "GPU-based four-dimensional general-relativistic ray tracing". Computer Physics Communications, Sciencedirect - doi.org/10.1016/j.cpc.2012.04.030.
- Thomas Müller (2014). "GeoViS—Relativistic ray tracing in four-dimensional spacetimes". Computer Physics Communications, Sciencedirect - doi.org/10.1016/j.cpc.2014.04.013. | <urn:uuid:20019142-b60a-4c5c-8188-246103811c80> | 4.1875 | 1,907 | Knowledge Article | Science & Tech. | 41.640938 | 95,524,954 |
Two distinct volcanic eruptions have flooded this area of Daedalia Planum with lava, flowing around an elevated fragment of ancient terrain.
New research in Geophysical Research Letters examines earthquake swarms caused by mounting volcanic pressure which may signal an imminent eruption. The research team studied Augustine Volcano in Alaska which erupted in 2006 ...
A volcano in the Galapagos Islands whose fiery eruption raised fears for the world's only population of pink iguanas has calmed, sparing the unique critters from danger, officials said Tuesday.
Call them '60s relics or hippy home accessories, lava lamps have been casting their dim but groovy light on interiors for half a century, having hit British shelves 50 years ago on Tuesday.
(Phys.org) —Hundreds of individual lava flows are seen frozen in time on the flanks of Olympus Mons, the largest volcano in the Solar System.
The Kilauea volcano sent more lava into Hawaii communities Friday, a day after forcing more than 1,500 people to flee from their mountainside homes, and authorities detected high levels of sulfur gas that could threaten the ...
The eruption of the Fuego volcano in Guatemala was likely a "pyroclastic surge" similar to the one that destroyed the ancient city of Pompeii, says volcanologist David Rothery of The Open University in England.
Nearly 1,500 residents were ordered to evacuate from their volcano-side homes after Hawaii's Kilauea Volcano erupted, sending molten lava to chew its way through forest land and bubble up on paved streets.
A new volcano eruption on Iceland could happen again soon, but will likely wreak less havoc than the one that caused massive airspace shutdowns earlier this year, experts said Thursday.
Io – Jupiter's innermost Galilean moon – is the most geologically active body in the Solar System. With over 400 active volcanic regions, plumes of sulfur can climb as high as 300 miles above the surface. It is dotted ... | <urn:uuid:781983cf-25d5-4ac6-b41b-4fad1b276c9d> | 2.984375 | 402 | Content Listing | Science & Tech. | 42.480278 | 95,524,957 |
New York: Deoxyribonucleic Acid (DNA), the genetic material of life, may help engineers build faster, cheaper computer chips by forming specific shapes through a process reminiscent of the ancient art of paper folding, researchers report.
“We would like to use DNA’s very small size, base-pairing capabilities and ability to self-assemble, and direct it to make nanoscale structures that could be used for electronics,” said Adam T Woolley, professor of chemistry at Brigham Young University (BYU).
The smallest features on chips currently produced by electronics manufacturers are 14 nanometers wide.
That is more than 10 times larger than the diameter of single-stranded DNA, meaning that this genetic material could form the basis for smaller-scale chips.
“The problem, however, is that DNA does not conduct electricity very well. So we use the DNA as a scaffold and then assemble other materials on the DNA to form electronics,” Woolley explained.
To design computer chips similar in function to those that Silicon Valley churns out, Woolley, in collaboration with Robert C Davis and John N. Harb at Brigham Young University, is building on other groups’ prior work on DNA origami and DNA nanofabrication.
Kenneth Lee, an undergraduate who works with Woolley, has built a 3D, tube-shaped DNA origami structure that sticks up like a smokestack from substrates such as silicon that will form the bottom layer of their chip.
The researchers’ ultimate goal is to place such tubes, and other DNA origami structures, at particular sites on the substrate.
In essence, the DNA structures serve as girders on which to build an integrated circuit.
“Nature works on a large scale and it is really good at assembling things reliably and efficiently. If that could be applied in making circuits for computers, there’s potential for huge cost savings,” the authors noted.
The researchers presented their work at the national meeting and exposition of the American Chemical Society (ACS) in San Diego, California, on Sunday. | <urn:uuid:cafa8146-12cb-4b34-93cb-4d2a998de598> | 3.875 | 440 | News Article | Science & Tech. | 35.279755 | 95,524,963 |
Another View - Pam Hunt and Loren Valliere: Local steps can fight climate change in NH
PAM HUNT and LOREN VALLIERE
Now that we've finally dug out from a cold, snowy winter in the Granite State, it's hard to get one's mind around the notion that the Earth is warming - but it is. This is the topic being discussed in wildlife and climate forums across the Granite State.
Attendees learn from biologists that impacts from climate change are already being reflected in New Hampshire's fish and wildlife populations.
New Hampshire's average temperatures are climbing in step with the global trend, largely due to carbon dioxide that traps energy in the atmosphere, creating a greenhouse effect. In addition, we have seen more droughts, heat waves, hurricanes, wildfires, flooding and sea level rise. Snow and rainfall patterns are shifting. Without a doubt, these changes will and do impact our native species and the habitats they depend upon.
A look at forests in our 84-percent forested state reveals that the forest products industry is a driving economic force here. As the climate changes, hardwoods may migrate north. Extreme weather events such as summer drought and intense cold in winter could cause ash, yellow birch, and sugar maple to decline, reports the Department of Environmental Services, wreaking a serious blow to the state's $3 million sugar maple industry.
Changes in our forests directly relate to how birds live and interact with their environment. Some studies say that our state bird, the purple finch, could disappear from much of its Northeast range because of habitat changes. Purple finch populations are already falling 1.7 percent a year and have declined by half in less than 50 years.
Bicknell's thrush, a rare North American songbird, breeds in spruce-fir forests near the highest elevations of mountains in northern New England. They have already disappeared from several peaks of the White Mountains where they were once common. As warming causes conifer forests to shrink, deciduous trees will become more prevalent, and the habitat for Bicknell's thrush could disappear from the state.
For that iconic New Hampshire animal the moose, climate change is delivering a triple threat: heat stress from rising temperatures, changing habitat conditions and increasing parasitism by winter tick. Moose are especially sensitive to temperature. When winter temperatures rise above freezing, they become heat-stressed. In summer, they are heat-stressed when temperatures rise above 60 to 70 degrees. Heat stress impairs their overall health, leading to lower weights, declining pregnancy rates and increased vulnerability to predators, disease and parasites.
Warmer temperatures allow larger numbers of winter ticks to survive, sometimes infesting individuals so severely that they suffer from anemia and even death. Kristine Rines, with the state Fish and Game Department, told the Washington Post on March 3, "We've had a higher tick load on moose this fall than we've ever seen, except for one year previously." She's already seen calves dying.
Long term, we need to start making serious attempts to curb carbon, and the Environmental Protection Agency is seeking public support for that right now. On the ground, implementing the New Hampshire Wildlife and Ecosystems Climate Adaptation Plan is the best way to start addressing the negative impacts on wildlife species. Under the leadership of the New Hampshire Fish and Game Department, more than 100 New Hampshire constituents were involved in writing this plan, which aims to help wildlife adapt to climate changes, including the increased temperatures, intense storms and changing snowpack. The plan outlines the largest vulnerabilities our state is facing and recommends the best way to address them.
As an example, New Hampshire's habitats are vulnerable to changes due to increased flooding, as we have a higher number of intense storms. Protecting intact floodplains that naturally slow and absorb floodwaters will protect our communities while ensuring long-term protection for important habitats. This is a common sense conservation strategy that will also provide a pathway for animals to move in response to climate changes.
New Hampshire citizens have shown dedication to reversing the negative impacts of climate change by supporting action at the national level. Citizens are also being educated about the changes that are inevitably coming our way, and the adaptation plan will help us deal with these challenges. We encourage you to work with your town's conservation commission to find ways the plan can help with future conservation planning and to make your voice heard on this conservation issue.
Pam Hunt is senior biologist at New Hampshire Audubon. Loren Valliere is a biologist with the National Wildlife Federation. | <urn:uuid:e8d7f3a4-5601-4d9c-afe3-bc859f5c28b3> | 3.328125 | 932 | News Article | Science & Tech. | 36.292136 | 95,524,973 |
Coast redwoods will be shifted northward into southern Oregon, if temperatures continue to warm and current rainfall amounts remain constant. This will be a significant habitat change, compared to that which they have experienced for the last several decades.
Early human teeth found in a cave in southern China suggest that humans migrated to Asia much earlier than previously thought, and long before they made their way to Europe. This changes our knowledge of early human distribution.
Researchers from the University of Bonn suggest that a prehistoric mammal, Spinolestes, may have suffered from hair loss. This fungal disease is commonly seen in many of the species' modern descendants.
Marine food chains may crumble in the wake of warming oceans and acidification, according to a global marine analysis. Even the slightest environmental change could have a much broader impact on a wider range of species than we realize.
Vines are becoming increasingly abundant in tropical forests as a result of climate change and severe seasonal drought and their rapid growth is harming trees and impacting carbon storage, a new study has revealed.
A featherwing beetle was measured to be 0.325mm. This is considered the world's tiniest, free-living insect.
Ants that called Europe their home 45 to 10 million years ago were actually more similar to modern-day ants now living in South East Asia than they are to their European cousins.
After making the most comprehensive study of fish species in the Salish Sea (the body of water that includes Puget Sound and the Strait of Georgia, University of Washington researchers have reported that species diversity there has increased 14 percent.
A new species recently added to the desmostylia group suggests that the hippo-sized suction-feeders were a more diverse group of animals than previously thought and ate in a very unique way.
Fish extend their jaws to decrease the distance between them and their prey. This evolutionary feeding advantage is known as jaw protrusion.
Embedded in the genetic code of several snake species was DNA that generally controls the development and growth of limbs in other animals.
Have you ever wondered why giraffes have such long necks? It turns out modern giraffes underwent a series of vertebrae elongation stages that ultimately gave them their extremely long necks.
Over the past five years, more than 200 new species have been found in the Eastern Himalayas and noted in scientific studies.
A new mammal species that has been dubbed the "hog-nosed rat" for its prominent flat pink, pig-like nose has been discovered in a remote part of Indonesia. | <urn:uuid:f9df7cdc-b44d-4bf2-93fe-ae86a33eaad5> | 3.609375 | 524 | Content Listing | Science & Tech. | 39.049924 | 95,525,030 |
A Tool and a Method for Obtaining Hydrologic Flow Velocity Measurements in Geothermal Reservoirs Page: 4 of 9
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to Digital Library by the UNT Libraries Government Documents Department.
The following text was automatically extracted from the image on this page using optical character recognition software:
PROCEEDINGS, Eleventh Workshop on Geothermal Reservoir Engineering
Stanford University, Stanford, California, January :21-23, 1986
A TOOL AND A METHOD FOR OBTAINING HYDROLOGIC
FLOW VELOCITY MEASUREMENTS IN GEOTHERMAL RESERVOIRS
C. R. Carriganl, J. C. Dunn2 and H. C. Hardeel
(2) Exploratory Energy
Downhole instruments based on a
thermal perturbation principle are
being developed to measure heat flow
in permeable formations where
convective transport of heat is
important. To make heat flow
measurements in these regions, the
ground water velocity vector must be
determined. A downhole probe has
been designed to measure the local
ground water velocity vector. 'The
probe is a cylindrical heat source
operated at a constant heat flux.
In a convecting environment, surface
temperatures on the probe are
perturbed from those values of a
purely conductive environment. With
the aid of analytical and numerical
models, these temperature
differences can be related to the
local velocity vector.
Hot wire or hot film anemometry is
commonly used in engineering
applications to determine flow
velocities of gases in pipes,
channels and other configurations.
A simple hot wire anemometer
measures the velocity of a gas
indirectly by relating the power
supplied to the sensor to the
velocity of the fluid in a direction
normal to the sensor (Dally et al,
1984). Heat produced by ohmic
dissipation within the sensor
element is removed by the flow of
cooler gas past the element. The
resultant cooling of the element
causes a change in its electrical
resistance that can be related to
the fluid velocity. We describe
here a tool based on a similar
approach that can be used to
estimate flow velocity in a
permeable medium. It is found that
application of the hot wire approach
is relatively uncomplicated if the
tool is placed in a permeable
formation so that the porous matrix
surrounding it is left more or less
undisturbed. This circumstance
could be achieved for a shallow well
drilled into a sandy zone with
backfilling of the hole.
Calculations indicate that the tool
can also be used in the wire-line
mode in an uncased hole if the
effects of the well pressure
distribution on the pressure field
in the porous medium are considered.
ANALYSIS OF OPERATION
A three dimensional analytical model
for flow in a permeable medium past
a heated prolate spheroidal body has
been developed by Romero (1983a).
The geometry of the problem solved
by Romero is illustrated in Figure
1. Here a slender body of radius,
a, and length, 21, is aligned
parallel to the vertical axis, z.
The azimuthal coordinate of the
Darcy velocity is given by $ while
its angle to the vertical is given
by 80. The dimensionless
quantity n,. which defines the
axial location on the probe, is
scaled by the half length, 1.
In a saturated porous medium,
Darcy's law and the Boussinesq
approximation are assumed to apply.
For a given velocity Um , which
characterizes Darcy flow in the far
field of the tool, a solution for
the pressure and temperature fields
in the vicinity of the heated tool
was obtained. In particular, the
solution for the temperature
distribution on the tool surface as
a function of both the far field
velocity and prescribed heat flux
across the tool surface is
required. There are two
significantly different length
scales that characterize the
problem. One is the characteristic
dimension of the tool while the
other is the thermal diffusion
length, a/U., where a is the
thermal diffusivity. The ratio of
the two lengths is given by the
Peclet number Pe. The typical
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Carrigan, C.R.; Dunn, J.C. & Hardee, H.C. A Tool and a Method for Obtaining Hydrologic Flow Velocity Measurements in Geothermal Reservoirs, article, January 21, 1986; United States. (digital.library.unt.edu/ark:/67531/metadc886194/m1/4/: accessed July 16, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department. | <urn:uuid:9ed3bd86-cf3d-4c29-9c5e-11b7adfd48fc> | 2.765625 | 1,176 | Truncated | Science & Tech. | 35.777114 | 95,525,069 |
Ten squares form regular rings either with adjacent or opposite vertices touching. Calculate the inner and outer radii of the rings that surround the squares.
Given a square ABCD of sides 10 cm, and using the corners as centres, construct four quadrants with radius 10 cm each inside the square. The four arcs intersect at P, Q, R and S. Find the. . . .
Triangle ABC is right angled at A and semi circles are drawn on all three sides producing two 'crescents'. Show that the sum of the areas of the two crescents equals the area of triangle ABC.
The ten arcs forming the edges of the "holly leaf" are all arcs of circles of radius 1 cm. Find the length of the perimeter of the holly leaf and the area of its surface.
This article gives an wonderful insight into students working on the Arclets problem that first appeared in the Sept 2002 edition of the NRICH website.
In LOGO circles can be described in terms of polygons with an infinite (in this case large number) of sides - investigate this definition further.
Can you prove that the sum of the distances of any point inside a square from its sides is always equal (half the perimeter)? Can you prove it to be true for a rectangle or a hexagon?
A circle touches the lines OA, OB and AB where OA and OB are perpendicular. Show that the diameter of the circle is equal to the perimeter of the triangle
Can you reproduce the design comprising a series of concentric circles? Test your understanding of the realtionship betwwn the circumference and diameter of a circle.
This pattern of six circles contains three unit circles. Work out the radii of the other three circles and the relationship between them.
What is the sum of the angles of a triangle whose sides are circular arcs on a flat surface? What if the triangle is on the surface of a sphere?
Equal circles can be arranged so that each circle touches four or six others. What percentage of the plane is covered by circles in each packing pattern? ...
The sides of a triangle are 25, 39 and 40 units of length. Find the diameter of the circumscribed circle.
A square of area 40 square cms is inscribed in a semicircle. Find the area of the square that could be inscribed in a circle of the same radius.
We have four rods of equal lengths hinged at their endpoints to form a rhombus ABCD. Keeping AB fixed we allow CD to take all possible positions in the plane. What is the locus (or path) of the point. . . .
Investigate the properties of quadrilaterals which can be drawn with a circle just touching each side and another circle just touching each vertex.
Thinking of circles as polygons with an infinite number of sides - but how does this help us with our understanding of the circumference of circle as pi x d? This challenge investigates. . . .
Given any three non intersecting circles in the plane find another circle or straight line which cuts all three circles orthogonally.
Investigate constructible images which contain rational areas.
M is any point on the line AB. Squares of side length AM and MB are constructed and their circumcircles intersect at P (and M). Prove that the lines AD and BE produced pass through P.
Triangle ABC has altitudes h1, h2 and h3. The radius of the inscribed circle is r, while the radii of the escribed circles are r1, r2 and r3 respectively. Prove: 1/r = 1/h1 + 1/h2 + 1/h3 = 1/r1 +. . . .
Three semi-circles have a common diameter, each touches the other two and two lie inside the biggest one. What is the radius of the circle that touches all three semi-circles?
Four circles all touch each other and a circumscribing circle. Find the ratios of the radii and prove that joining 3 centres gives a 3-4-5 triangle.
A kite shaped lawn consists of an equilateral triangle ABC of side 130 feet and an isosceles triangle BCD in which BD and CD are of length 169 feet. A gardener has a motor mower which cuts strips of. . . .
A farmer has a field which is the shape of a trapezium as illustrated below. To increase his profits he wishes to grow two different crops. To do this he would like to divide the field into two. . . .
Draw three equal line segments in a unit circle to divide the circle into four parts of equal area.
Explore the geometry of these dart and kite shapes!
If you continue the pattern, can you predict what each of the following areas will be? Try to explain your prediction.
Have a go at creating these images based on circles. What do you notice about the areas of the different sections?
Recreating the designs in this challenge requires you to break a problem down into manageable chunks and use the relationships between triangles and hexagons. An exercise in detail and elegance.
Nick Lord says "This problem encapsulates for me the best features of the NRICH collection."
Learn how to draw circles using Logo. Wait a minute! Are they really circles? If not what are they?
Straight lines are drawn from each corner of a square to the mid points of the opposite sides. Express the area of the octagon that is formed at the centre as a fraction of the area of the square.
How efficiently can you pack together disks?
Two circles of equal size intersect and the centre of each circle is on the circumference of the other. What is the area of the intersection? Now imagine that the diagram represents two spheres of. . . .
A cheap and simple toy with lots of mathematics. Can you interpret the images that are produced? Can you predict the pattern that will be produced using different wheels?
For any right-angled triangle find the radii of the three escribed circles touching the sides of the triangle externally.
The challenge is to produce elegant solutions. Elegance here implies simplicity. The focus is on rhombi, in particular those formed by jointing two equilateral triangles along an edge.
Two semi-circles (each of radius 1/2) touch each other, and a semi-circle of radius 1 touches both of them. Find the radius of the circle which touches all three semi-circles.
The centre of the larger circle is at the midpoint of one side of an equilateral triangle and the circle touches the other two sides of the triangle. A smaller circle touches the larger circle and. . . .
Two perpendicular lines are tangential to two identical circles that touch. What is the largest circle that can be placed in between the two lines and the two circles and how would you construct it?
A small circle fits between two touching circles so that all three circles touch each other and have a common tangent? What is the exact radius of the smallest circle?
What is the ratio of the area of a square inscribed in a semicircle to the area of the square inscribed in the entire circle?
Medieval stonemasons used a method to construct octagons using ruler and compasses... Is the octagon regular? Proof please.
Take any rectangle ABCD such that AB > BC. The point P is on AB and Q is on CD. Show that there is exactly one position of P and Q such that APCQ is a rhombus.
The diagonals of a trapezium divide it into four parts. Can you create a trapezium where three of those parts are equal in area?
Where should runners start the 200m race so that they have all run the same distance by the finish?
See if you can anticipate successive 'generations' of the two animals shown here.
The largest square which fits into a circle is ABCD and EFGH is a square with G and H on the line CD and E and F on the circumference of the circle. Show that AB = 5EF. Similarly the largest. . . .
By inscribing a circle in a square and then a square in a circle find an approximation to pi. By using a hexagon, can you improve on the approximation? | <urn:uuid:68ecbdc4-08da-41da-b6fd-c32b80bc2691> | 3.859375 | 1,736 | Content Listing | Science & Tech. | 67.195868 | 95,525,070 |
A parasitic fungus that must kill its ant hosts outside their nest to reproduce and transmit their infection, manipulates its victims to die in the vicinity of the colony, ensuring a constant supply of potential new hosts, according to researchers at Penn State and colleagues at Brazil's Federal University of Vicosa.
Previous research shows that Ophiocordyceps camponoti-rufipedis, known as the "zombie ant fungus," controls the behavior of carpenter ant workers -- Camponotus rufipes -- to die with precision attached to leaves in the understory of tropical forests, noted study lead author Raquel Loreto, doctoral candidate in entomology, Penn State's College of Agricultural Sciences.
"After climbing vegetation and biting the veins or margins on the underside of leaves, infected ants die, remaining attached to the leaf postmortem, where they serve as a platform for fungal growth," Loreto said.
The fungus grows a stalk, called the stroma, which protrudes from the ant cadaver. A large round structure, known as the ascoma, forms on the stroma. Infectious spores then develop in the ascoma and are discharged onto the forest floor below, where they can infect foraging ants from the colony.
This fungal reproductive activity must take place outside the ant colony, in part because of the ants' social immunity, which is collective action taken to limit disease spread, explained study co-author David Hughes, assistant professor of entomology and biology, Penn State.
"Previous laboratory studies have shown that social immunity is an important feature of insect societies, especially for ants," Hughes said. "For the first time, we found evidence of social immunity in ant societies under field conditions."
The researchers tested social immunity by placing 28 ants freshly killed by the fungus inside two nests -- 14 in a nest with live ants and 14 in one with no ants. They found that the fungus was not able to develop properly in any of the 28 cadavers. In the nest with live ants, nine of the 14 infected cadavers disappeared, presumably removed by the ants in an effort to thwart the disease organism.
"Ants are remarkably adept at cleaning the interior of the nest to prevent diseases," Hughes said. "But we also found that this fungal parasite can't grow to the stage suitable for transmission inside the nest whether ants are present or not. This may be because the physical space and microclimate inside the nest don't allow the fungus to complete its development."
Next the researchers set out to record the prevalence of the fungus among ant colonies within the study area, which was located at the Mata do Paraíso research station in southeast Brazil. After marking and searching 22 transects covering a total of 16,988 square miles, they discovered that all 17 nests found had ant cadavers attached to leaves beside the colony, suggesting a fungal prevalence of 100 percent at the ant population level.
In a more detailed, 20-month survey of four of those ant colonies, the scientists measured parasite pressure by mapping the precise locations of fungus-killed ants and foraging trails in close proximity to the nests.
"We limited our survey to the immediate area surrounding the nest because this is the zone the ants must walk through to leave and return to the colony," Loreto said. "To better understand the path workers ants took, we measured and mapped in 3-D the trails formed by the ants, and that allowed us to determine spatial location of potential new hosts, which would be on the foraging trails."
By measuring the position of manipulated ants and plotting these locations with respect to the nest, the researchers established that infected ants die on the "doorstep" of the colony.
"What the zombie fungi essentially do is create a sniper's alley through which their future hosts must pass," Hughes said. "The parasite doesn't need to evolve mechanisms to overcome the effective social immunity that occurs inside the nest. At the same time, it ensures a constant supply of susceptible hosts."
Despite the high prevalence of infected colonies and persistence of the fungus over time, the researchers did not observe colony collapse, suggesting that the parasite functions as a long-lasting but tolerable condition for the ants.
"We suggest that the parasite can be characterized as a 'chronic disease' that, as in humans, can be controlled but not cured," Loreto said.
The research, which was funded by CAPES-Brazil and Penn State, was published today (Aug. 18) in PLOS ONE.
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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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Table of Contents
When building a website using Zend Framework MVC layers, your view
scripts will typically be just snippets of HTML pertinent to the
requested action. For instance, if you had the action "
you might create a view script that iterates through the users and presents an unordered
<?php if (!count($this->users)): ?>
<li>No users found</li>
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<?php foreach ($this->users as $user): ?>
<?php echo $this->escape($user->fullname) ?>
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Since this is just a snippet of HTML, it's not a valid page; it's missing a DOCTYPE declaration, and the opening HTML and BODY tags. So, the question is, where will these be created?
In early versions of Zend Framework, developers often created "header" and "footer" view scripts that had these artifacts, and then in each view script they would render them. While this methodology worked, it also made it difficult to refactor later, or to build composite content by calling multiple actions.
The Two Step View design pattern answers many of the issues presented. In this pattern, the "application" view is created first, and then injected into the "page" view, which is then presented to the client. The page view can be thought of as your site-wide template or layout, and would have common elements used across various pages.
Within Zend Framework,
Zend_Layout implements the Two Step View | <urn:uuid:d10b74d0-a213-4193-bf82-df50c6ee8f48> | 2.90625 | 352 | Documentation | Software Dev. | 66.504348 | 95,525,093 |
BSGF - Earth Sciences Bulletin 2017, 188, E3
Geological fluid flow in sedimentary basins
Les fluides géologiques dans les bassins sédimentaires
Géosciences Montpellier, UMR 5243–CC 60, Université Montpellier 2,
Montpellier cedex 05, France
2 GEOAZUR, UMR 7329, 250 rue Albert-Einstein, Les Lucioles 1, Sophia-Antipolis 06560 Valbonne, France
* Corresponding author: firstname.lastname@example.org
Key words: TOC / organic matter preservation / fluid seep / methane hydrates / bottom-simulating reflector (BSR) / dynamic seepage / seismic pipes / fluid migration
Mots clés : expulsion des fluides / préservation de la matière organique / hydrates de gaz / cheminées sismiques / migration des fluides
For over 50 years, sedimentary basins have been considered as the lithosphere's surface film, belonging to the subsurface domain and containing the vast majority of accessible mineral and energy resources. Beyond their human use, sedimentary basins are more importantly the ultimate exchange interface between the earth's main reservoirs. Firstly, between the upper lithosphere and the atmosphere-hydrosphere reservoirs, exchanges are mainly vertical. Next, between the onshore reservoirs, i.e., on the continental part, and the offshore reservoirs, i.e., in the submerged part of the margins, exchanges are lateral and may take place over great distances. Unexpected low accumulations and/or dry holes are becoming more frequent in petroleum exploration and gaining an understanding on lateral migration of fluids and bypass system are one of the geological challenges that must be addressed to reach ultimate reservoirs in the coming years.
In such context, the French coordination program Action Marges (AM) has been launched in 2008 in order to focus the continental margin research on a cross disciplinary research and develop new concepts that have an important impact for society, for resources and for risk assessment. The Action Marges project is coordinated by INSU with financial contribution of TOTAL, CNRS, BRGM and IFREMER. One of the themes is dedicated to “Fluids − Organic Matter − Mineral Matter” (FO3M) and the challenge was to define fluid flow as the centerpiece of a cycle starting from the organic matter preservation at seabed, its transformation during burial forming fluids, the upward fluid migration through fine-grained sediments, the temporarily fluid storage into reservoirs such as sedimentary bodies or gas hydrates, the fluid expulsion at seafloor, to its implications on seabed stability or climate change.
This special issue on geological fluid flow in sedimentary basins aims at bringing together recent results from the scientific community involved in the FO3M project since 2012, with a special focus on the interplay between mineralogical, geochemical, physical and biological processes occurring during fluid remobilization and migration within the shallow interval (0–1000 m) of sedimentary basins.
The initial sediment lithification starts with complex interactions involving minerals, shallow interstitial water, decomposing organic matter and living organisms. This is the eogenesis domain (0–1000 m below seafloor) in which the sediments are subjected to physical, chemical and mechanical transformations defining the early fabric of rocks (Fig. 1). This interval is intensively prospected for its geological resources (hydrocarbons, metal deposits, geothermal energy). In most basins worldwide, it consists of very fine-grained sediments and it is supposed to play the role of a seal for fluid migration. Local sand-prone deposits of various origin, architecture and thickness can also be found, acting as pathways or reservoirs for fluids.
For the first time, the solid phase BrOrg has been evidenced as a conservative tracer of the debromination of sedimentary organic matter in a shallow core (< 50 m) taken on the Nile deep-sea fan (Murat et al., this issue). The rate of debromination illustrates the complex interplay between organic matter, microbes and inorganic compounds in unconsolidated sediments. It obviously depends on the TOC, meaning that it increases with TOC up to 3% due to the availability of the bacterial population. However, the debromination process decreases for TOC higher than 4%. This is of high interest for organic-matter transformation as the BrOrg tracer determines how fine-grained organic-rich intervals become potential source rocks at depth and how bacterial populations modify fluids and organic matter characteristics during early stages of burial (Fig. 1). In addition, the BrOrg can be used as a tool for defining intervals that were “fluid engineers” in the eogenesis domain once the organic matter has been transformed at depths where diagenesis is the most active process for lithification (> 1000 m below seafloor).
However, the eogenesis domain is commonly affected by polygonal faulting due to a volume loss by contraction of smectite-prone clay sediments during burial (Andresen and Huuse, 2011; Cartwright, 2011; Gay et al., 2007). This process is of high interest to constrain fluids circulation within fractured reservoirs and/or preservation of the sediment-cover integrity but it is still not well constrained as this interval can either promote the migration of fluids from underlying reservoirs (Gay et al., 2004; Lonergan et al., 1998). In addition, mineralized fluids intensify diagenesis in the fracture planes, rendering this interval all the more impermeable (Laurent et al., 2012). The detailed analysis of the geometric relationships between high-impedance seismic anomalies and polygonal fault pairs reveals that they can act as a seal during early stages of burial (Ho et al., 2016). In the Congo Basin, the Pliocene-present interval contains widespread fluid escape features, at seabed and in the subsurface, indicating past and ongoing bypass of the regional seal which is intensely affected by a major polygonal fault system (Gay et al., 2004). Casenave et al., this issue have shown that this polygonal fault interval might also have sealing properties. In this case, fluids are mainly driven along major faults to reach the seabed, leading to more focused and localized fluid seeps (Fig. 1). The next challenge will be then to define where, when and how does this polygonal fault interval occur. This can only be done by understanding the behavior of clay grains and fluids during early burial stages.
In the Sobrarbe Delta (Eocene Ainsa Basin), diagenetic conditions were limited to low temperatures (up to 75 °C), meaning that sediments have been buried to a maximum of 2 km (Odonne et al., this issue). Both some sliding surfaces and their surrounding deposits were investigated. Results reveal higher smectite ratio close to the sliding surfaces and smectites were found at the wall of dissolution voids of K-feldspars (Fig. 1). This indicates that fluids preferentially circulated following the sliding surfaces that acted as major heterogeneity within the sediment pile. In these conditions, clay minerals such as smectite appear as a robust marker of shallow fluid circulation as the kaolinite requires a temperature of 130–140 °C to change into illite.
Schematic block illustrating new developments since 2012 in geological fluid production, migration and expulsion in sedimentary basins, based on studies conducted through the FO3M thematic action in the Action Marges project.
Once fluids (water, gas, oil or a mix) reach the seafloor, they are expelled in the water column forming sub-circular depressions called pockmarks (Hovland and Judd, 1988). Pockmarks have been reported in various depositional systems at water depths ranging from 30 m to over 3000 m (for a detailed review see Rollet et al., 2006; Gay et al., 2007). They generally form in unconsolidated, fine-grained deposits. They are cone-shaped circular or elliptical depressions, ranging from a few meters to 800 m or more in diameter and from 1 m to 80 m in depth. They concentrate in fields extending over several square kilometers. For the last decade, discoveries of new fluid seep structures were not reported although both academic and industrial surveys intensified.
However, the use of high-resolution geophysical imagery systems leads to the identification of unknown high-density field of pockmarks (about 3500 sub-circular pockmarks per square km) in unsuspected shallow marine environment (about 35 m water depth) like the Bay of Concarneau (France) (Baltzer et al., this issue). The pockmarks appear to be active as the fields limits coincide with the settlements of Haploops tube mats covering muddy deposits. To date, this is the highest density of pockmarks ever found in marine environment (Fig. 1). The acquisition of bathymetry and other geophysical tools in the same area in 2011 and 2014 was essential in order to determine lasting of Haploops communities related to fluid seeps within pockmarks.
In the Lower Congo Basin (LCB), the combined use of various datasets acquired during the last 15 years and including multibeam bathymetry, seismic data, seafloor videos, seafloor samples and chemical analyses of both carbonate samples and of the water column allowed the identification of two distinctive associations of pockmark-like seabed venting structures, located in water depths of 600–700 m (Casenave et al., this issue). These two features are called “spiders structures” because of their morphology consisting of a large and flat sub-circular depression (the body) surrounded by elongated depressions (the legs). The body consists of muddy low-reflective hemipelagic sediments, covered by patches of bacterial mats and empty shells, and seems dormant while the legs appear to be the present-day active seep location (Fig. 1). This observation is similar to what was already described for more conventional pockmark structures on the Nile margin (Bayon et al., 2008; Dupré et al., 2010; Migeon et al., 2014; Praeg et al., 2014) but it is the first time that such a specific seabed planform morphology associated with such a fluid-circulation activity is reported.
Pockmarks and gas seeps can also be detected on acoustic records as long as they are active (Dupré et al., 2015). This is the case in the Bay of Concarneau where acoustic flares were identified on Chirp profiles (Baltzer et al., this issue). This is also the case on the Romanian sector of the Black Sea where widespread gas flares were evidenced in the water column related to high fluid fluxes escaping from the seabed (Riboulot et al., this issue). Gas flares are a useful tool to easily identify active pockmarks during multibeam and 2D high-resolution seismic surveys (Fig. 1). They develop above active pockmarks and might be related to the presence of a gas-hydrate stability zone.
On the geophysical record, either 2D or 3D seismic data, vertical fluid pathways called pipes (or chimneys) are usually imaged as systematic disruptions and/or offset of the reflections within sub-vertical zones, 50–1000 m wide and up to 1000 m high (Løseth et al., 2011). This interpretation is also supported by observation of amplitude enhancement or dimming. On seismic profiles, the internal structure of pipes is characterized by bent reflections with offset upward (pull-up effect) or downward (pull-down effect) relative to the host stratigraphy by 20 to 150 ms TWT. Pipes are interpreted to represent a high-permeable vertical zone called a seal bypass system (Cartwright et al., 2007). They are thought to be caused by high fluid overpressure hydro-fracturing sediments of low permeability (Arntsen et al., 2007; Rodrigues et al., 2009). This geophysical characterization seems actually well constrained in space and time. However, using a set of derived seismic attributes, it is now possible to identify the root of a pipe (i.e., the depth at which fluids are originating from) and the paleo-pockmark surface (i.e., the level representing the paleo-seafloor at the time the fluid expulsion started [was active?]). In the Gulf of Lion, the fluid pipe induces a deformation of surrounding unconsolidated sediments during upward migration, leading to the formation of a cone in cone or V-shaped structures (Gay et al., this issue). A multi-attribute calculation made on 3D seismic data allows the precise 3D mapping of the points of fluid injection while the top of the cone structure marks the top of the focused migration (Fig. 1).
It is classically invoked that most of the fluids reaching the seabed are originating from shallow buried levels (Fig. 1) although when carbonate crusts build at the seafloor there is undoubtedly a contribution of deeper fluids allowing oil or thermogenic gas to be expelled (León et al., 2010, 2014). This is the case in the Gulf of Lion (Gay et al., this issue), on the Romanian shelf (Riboulot et al., this issue) or in the Bay of Concarneau (Baltzer et al., this issue) where fluid releasing is attested. These vertical chimneys or pipes are among other acoustic anomalies usually present in the shallow sub-surface due to gas accumulations or carbonate precipitation (Fig. 1). In the Lower Congo Basin, such anomalies were identified on either 3D seismic data, HR 3D seismic data or 2D-AUV data (Casenave et al., this issue) corresponding to bright spots, elongated acoustic anomalies or black patches.
However, even with 3D seismic imagery, the full architectural pattern of the fluid network remains very complex to determine. Only a few examples of modern fluid-related systems have been studied in details at sea, probably because of the limited number of areas where VHR investigations of the seafloor/sub-surface together with 3D seismic data exists. It is then possible to better understand these features on field analogues, once the stratigraphic intervals hosting them have been uplifted due to tectonic activity and brought above the sea-level (Fig. 1). For instance, in the uplifted accretionary prism of Hikurangi Margin (New-Zealand), tubular concretions are outcropping in several Miocene mudrocks intervals (Malié et al., this issue). Most of the pipes are sub-vertical with their length-axis perpendicular or sub-perpendicular to the bedding plane. They are 10 to 40 cm in diameter and 50 cm to 10 m in length. In some cases, they are inter-connected, forming a real plumbing system. A direct comparison with seismic-scale features is still not realistic to manage because their dimensions are far below the seismic resolution. Anyway, this suggests that a fluid pipe few hundred-meters wide identified on the seismic record is most probably a set of several small-scale pipes together propagating in a large area of sediment impregnated with fluids (Fig. 1). This should be the target for the development of future research fields.
The sub-vertical fluid pipes (or chimneys) are often disrupted at depth by a high-amplitude reflection parallel to the seafloor. This reflection is interpreted as a bottom-simulating reflector (BSR) corresponding to the lower thermodynamic limit of the gas-hydrate stability zone (Shipley et al., 1979; Kvenvolden 1988; Hyndman and Spence, 1992). This can be also considered as the top of the free-gas zone beneath the hydrates (MacKay et al., 1994). BSRs are characterized by a reverse polarity reflection compared to the seafloor. This is due to a decrease in seismic impedance and, therefore, of seismic velocity. The main restriction for the occurrence of hydrates is the presence/supply of sufficient amounts of stabilizing gas molecules (Rempel and Buffett, 1997). As outlined by Egorov et al. (1999), the steady-state model for gas hydrates requires a methane flux from below to compensate for its diffusive dissipation into the pore water (Sultan et al., 2014). This statement is confirmed on the Romanian shelf where BSRs are deflected upward (Riboulot et al., this issue), suggesting a localized positive heat flow anomaly probably due to an ascending movement of fluids through the sedimentary column (De Batist et al., 2002; Gay et al., 2006). It means that gas hydrates are locally not impermeable, allowing fluids to migrate upward along any major discontinuity such as faults, and then to form pockmarks at the seabed (Fig. 1). So, there is a close association between BSRs at depth, indicating an active fluid flux, and seafloor pockmarks. This is also the case in the Lower Congo Basin where the new “spider structures” are located above patches of BSR (Casenave et al., this issue).
As gas hydrates are usually considered impermeable, additional free gas may migrate laterally right beneath the hydrates. Once they find a way up, they can escape to the seabed. On the seismic record, this kind of seepage is often evidenced by hyperbolae located at the landward termination of the BSR and overlaid with seafloor gas escape structures (Fig. 1) (Riboulot et al., this issue; Casenave et al., this issue).
Gas hydrates have a dual role in sedimentary basins as they temporarily store fluids migrating from deeper geological horizons to their stability zone or as free gas beneath them and they avoid fluids to reach the seabed with properties similar to a barrier. In consequence, they can be considered as both a reservoir and a cover in the shallow subsurface (Fig. 1).
In the uplifted accretionary prism of Hikurangi Margin (New-Zealand), trending of fossil tubular carbonate concretions coincides with tectonic lineament suggesting that the main factor controlling the fluid expulsion and location is the tectonic activity (Malié et al., this issue). It is suggested that the tectonic uplift together with fault activity can shift the depth of the Hydrate Stability Zone (HSZ), leading to dissociation of pre-existing hydrates and releasing of methane.
Gas hydrates are also “climate sensitive” as they form or dissolve in response to sea-level variations controlling bottom seawater temperatures. In the Lower Congo Basin, the various stratigraphic levels hosting fluid escape structures have been correlated to sea-level rises following the latest Holocene lowstands (Casenave et al., this issue). This is due to free gas naturally migrating landward due to the pronounced tilting of the base of the gas hydrate stability zone at 600–700 m water depths (close to theoretical pinch-out of the BSR).
This relation with sea-level variations has also been evidenced in the Gulf of Lion where most of the modern pockmarks were formed during the last sea-level rise (Gay et al., this issue). León et al. (2014) have shown that in the western Mediterranean Sea, the propagation of internal waves alongshore may act together with the general sea-level rise at the beginning of the transgressive period as a hydraulic pump for fluids trapped at shallow depths, resulting in the formation of pockmarks (Fig. 1). It suggests that, at the beginning of each transgression, large amount of methane-rich fluids might be released into the ocean and atmosphere, possibly increasing the greenhouse effect (Dunkley Jones et al., 2010).
The effect of hydraulic pumping can be responsible for the formation of the large fields of pockmarks in the Bay of Concarneau (Baltzer et al., this issue). At a shorter time-scale, the high-frequency expulsion activity may be related to the action of spring tides (Fig. 1). Although the initial pockmark craters are thought to be formed during seismic events (Baltzer et al., 2014), pockmarks could be activated when the tidal pressure would be high enough during spring tides, leading to the formation of plumes in the water column.
As previously proposed by Hasiotis et al. (1996), these observations imply that gas supply towards pockmarks is a continuous process during the life-span of the seep structure (Fig. 1). It also means that the sediments within the migration pathways are loaded with gas, which is of high interest for seafloor hazards.
Recent studies of fluid migrations in sedimentary basins have shown that these phenomena are ubiquitous and interact with the surrounding sedimentary rocks over the basin's history, from its early opening stages, to the mature infilling, or even the ultimate exhumation stages. Finally, these fluids act as major markers for the geodynamic events that structure the basins.
In order to understand the role of fluids in sedimentary basins, several challenges must be met. We must, in particular, determine the source of the fluids, their pathways and the timing of these migrations and releasing at the seafloor. Thus, depending on the geodynamic context of a given basin and on its evolution over time, several fluid migration histories may overlap, though these fluid events are all preserved in the sedimentary record. The goal is thus to identify a number of geophysical, mineralogical and geochemical markers of fluid migration and expulsion. They are closely controlled:
by early sediment deformations and fracturing;
by the location of bodies and sedimentary sequences likely to temporarily store and/or conduct fluids laterally all along the margin;
by allocyclic phenomena such as sea-level variations.
In this special issue, the methods have combined complementary approaches to analyse fluid migrations in sedimentary basins:
geophysical characterisation based on 2D, 3D and 2D-AUV seismic data, core and exploratory well data;
sedimentological and mineralogical characterisation based on petrophysical data and crystallographic and texture analyses;
identification of geochemical markers on samples collected at various depths of the sedimentary column up to the surface;
definition of the mechanical parameters triggering and controlling fluid re-mobilisation.
The final goal of this research field will be to generate a concept of “fluid sequences” that, in a similar fashion to sequence stratigraphy, will be used as a direct approach to determine the migration pathways and potential traps, and to quantify the volume and nature of expelled fluids. This is of major importance as it will help determining the timing and activity of seafloor fluid expulsion leading to geohazard assessment (catastrophic fluid blow-out, landslide triggering, etc.). As a reverse approach, it will make possible to define the evolutionary status of a sedimentary basis and to infer its geodynamic context at any given period of its history. The aim is thus to significantly improve fluid expulsion models in sedimentary basins, which is a challenge for basin exploration (open window over the petroleum system, seafloor stability and fluid accumulation).
We would like to thank Cécile Robin, Gianreto Manatschal and Sylvie Leroy who have managed the scientific board of Action Marges project for the last 8 years. We thank all partners involved in this project, such as TOTAL, IFREMER, BRGM and CNRS-INSU.
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Greener Energy Generation Alone Will Not Help Us Reach Climate Goals
Transport, buildings and industry need to start using lower carbon sources of energy now if we are to avoid the worst impacts of climate change.
Transporting goods, heating buildings and manufacturing products all rely on fossil fuels. Without serious change now in these sectors, we will be ‘locked in’ to increased carbon dioxide (CO2) emissions for decades, say the authors of a new report.
The Paris Agreement, adopted in 2015, sets a target for global warming of well below 2°C, and potentially 1.5°C, to avoid the worst impacts of climate change. Many of the current plans to reach this goal revolve around making energy generation greener, for example by replacing coal and natural gas-fired power plants with wind and solar power.
Green energy alone not enough
However the new study, published today in Nature Climate Change and featuring Imperial College London researchers, shows cleaning up energy supply alone will not be enough on its own to reach the Paris Agreement goals. Instead, CO2 savings will also need to be made in the industry, transport and building sectors.
For example, transport relies on the internal combustion engine, which burns fossil fuels like petrol. Electric car engines could reduce the CO2 emissions from personal cars and road transport, but the same types of engines will not be able to replace the engines used in shipping or aviation.
Without efforts in these sectors, say the authors, we will have to rely more heavily on removal technologies that extract CO2 from the atmosphere, which are uncertain and unproven on a large scale.
Co-author of the study Dr Joeri Rogelj, from the Grantham Institute – Climate Change and Environment at Imperial, said: “Ensuring that global warming is kept within safe bounds requires us to stop emitting carbon dioxide into the atmosphere. Nobody expects this to happen overnight, but decisions made today matter much longer than often appreciated.”
“Our study shows that even if we start being serious about emissions reductions today, about 25 years’ worth of today's emissions are still expected to be produced by the accumulated industrial, transport and building infrastructure of the world.”
'Residual' CO2 emissions
Infrastructure that relies on carbon-based energy, such as the production of concrete and the majority of freight transport, is often built to last for decades. This means that unless concerted efforts are made to change these systems now, they will continue to emit carbon dioxide far in the future. These ‘residual’ CO2 emissions make a big difference in future predictions.
The Paris targets of keeping global warming well below 2°C means there is a limited remaining ‘budget’ for how much CO2 we can release, ever. For example, to keep global warming to just 1.5°C, several studies suggest we may only be allowed to emit as little as 200 Gigatons of CO2, which is in stark contrast to the 4000 Gigatons of CO2 that would be emitted if current trends continue.
Uncertain and potentially risky technologies
This has given rise to concerns about the increasing reliance on uncertain and potentially risky technologies for so-called negative CO2 emissions, such as bioenergy plantations or carbon capture and storage (CCS).
Working within different carbon budgets, the team modelled scenarios of policy action on climate change to determine how the targets may be met.
Lead author of the study Dr Gunnar Luderer, from the Potsdam Institute for Climate Impact Research in Germany, said: “We found that even with enormous efforts by all countries, our calculations show that residual fossil carbon emissions will remain at about 1000 Gigatons of CO2.”
“This seems to be a lower end of what can be achieved with even the most stringent climate policies, because much of the residual emissions are already locked into the system due to existing infrastructures and dependencies on fossil fuels.”
Ramping up ambitions
The team found that to aim for the ambitious 1.5°C target for 2100 would mean that at least 600 Gigatons of CO2 removal would be required under the assumptions of their study, although other recent research to which Imperial College London researchers contributed shows this can also be a lot less.
Co-author Dr Elmar Kriegler, from the Potsdam Institute for Climate Impact Research, said: “While it may still be difficult to determine the exact remaining CO2 budget for 1.5°C, one thing is very clear: ambitions to reduce fossil fuel emissions have to be ramped up substantially and soon to keep doors open to meet the Paris targets.”
This article has been republished from materials provided by Imperial College London. Note: material may have been edited for length and content. For further information, please contact the cited source.
Residual fossil CO2 emissions in 1.5–2 °C pathways. Gunnar Luderer et al, Nature Climate Change volume 8, pages626–633 (2018) https://doi.org/10.1038/s41558-018-0198-6.
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How can the decay of muons produced in the Earth’s upper atmosphere provide evidence for the Special Theory of Relativity?
What is relativity all about? Relativistic velocity: When 1 + 1 = 1 Why can’t you go faster than light? Relativity: how people get time dilation wrong Relativity’s key concept: Lorentz gamma Einstein’s clocks Twin paradox: the real explanation Length … Continue reading
Are you really standing still? The Michelson-Morley Experiment Time dilation The Cosmic Speed Limit Mass-Energy Equivalence – E=mc²
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Thousands of scientists and engineers in 11 countries are gearing up for the construction and launch of the Square Kilometre Array. The SKA is the world’s largest radio telescope, and the boffins hope it will bring humans a glimpse into beginning of the universe.
Sadly for us, there won't be any hardware on New Zealand soil, after our bid was rejected in 2012 in favour of Australia and South Africa. But it's still a huge thing for Kiwi scientists and mathematicians, says Steve Cotter, CEO of New Zealand’s research and education network Reannz.
As part of the SKA project, Reannz is helping Kiwi researchers prepare to receive and analyse the huge amounts of data that will be collected by the instruments.
Idealog talked to Cotter about the history of the Square Kilometre Array project and what it means for New Zealand.
IDEALOG: What is the SKA?
Steve Cotter: A (really) big, distributed telescope, made up of thousands of dishes and millions of dipole radio receptors, with an effective collecting area of a square kilometre, spread out over Western Australia’s Murchison Shire and the Karoo Desert in South Africa.
The SKA will allow us to monitor and listen to radio waves, rather than optical light (as with traditional telescopes). It will be 100 times as sensitive – and provide image resolution quality 50 times greater – than the biggest present-day telescope, the Hubble Space Telescope.
SKA antennae. Photo courtesy of Astron
The goal of the project is to help answer questions about fundamental physics and the ways the universe functions. Some of the things the SKA hopes to understand are the origins of our universe, dark matter’s role in its creation and the origins of cosmic magnetism.
Peter Quinn from the International Centre for Radio Astronomy Research has called the SKA an “enormous ear”, listening for signals from the first stars and galaxies born in the universe.
For example, the SKA will observe pulsars and black holes to test Einstein’s theory of gravity. It will also look for signals of extraterrestrial life elsewhere in the galaxy.
It’s a multi-billion dollar project that commenced in 2012 and is set for completion between 2020 and 2023.
Infographic courtesy of SKA
ID: Why is it interesting and why should we care?
SC: The SKA will allow us to look both far away and backwards in time to the beginning of the universe. We may even be able to answer one of those ultimate human questions – are we alone?
The project moved one step closer last month, when members of the SKA organisation decided negotiations should start with the UK government to establish a permanent headquarters at the University of Manchester.
ID: Who is working on it?
SC: An international consortium of 11 nations, (comprising around 40% of the world’s population) is helping to fund the project. These include five European countries, China, India, Australia, New Zealand, Canada and South Africa. Other developing countries in Africa may join the project.
ID: Why work on this now?
SC: Science works towards a 20-year future. Big science is not an end or a means but more a realisation that thinking hard about something then developing capacity always returns interesting results.
The SKA will allow us to look both far away and backwards in time to the beginning of the universe. We may even be able to answer one of those ultimate human questions – are we alone?
ID: Are there Kiwis working on SKA?
SC: Yes, New Zealand is one of the main member partners. Apart from Reannz, there are a number of other Kiwi organisations, including AUT University. As New Zealand’s leading tertiary institute in astronomy, a number of AUT scientists and engineers have been involved across a number of aspects of the project. This includes the design of the Survey Correlator, which will combine signals from across the thousands/millions of receivers.
AUT has also led the majority of modelling/prototyping for the project. In particular, all the data collected from the SKA telescopes will move through an algorithm or hardware being designed by AUT computer and mathematical sciences expert Dr Andrew Ensor and his team. Teams from four other New Zealand universities (Massey, Otago, Victoria and Auckland) will also be involved in a project to use data collected by the SKA precursors (MeerKAT and ASKAP) to test the data delivery and analysis pipeline, so that researchers will be able to access the SKA data once it goes live.
ID: What is Reannz's part?
SC: The telescopes are expected to generate around 960 Petabytes of raw data every day - the equivalent of streaming approximately 320 million hours of HD video on Netflix.
We will provide access to the Reannz’ advanced network, to test various methods for the movement of such high levels of data. We expect ultimately data will be downloaded/transferred in a matter of hours rather than weeks.
Reannz will be working behind the scenes, leveraging relationships with our peers in other countries, to build and maintain connectivity for data to pass from the SKA to New Zealand, allowing scientists to focus on their science, rather than worrying about the logistics of data collection and data analysis.
ID: Is this exciting for NZ science?
SC: It provides a range of PhD opportunities, via the NZ institutions involved in building the central processor that the super computer will use to collate the range of signals it receives from instruments into usual data.
Any network technology improvements or discoveries made by Reannz, as it moves and analyses the SKA data will then become available to all New Zealand researchers and scientists, benefiting the whole science community. These improvements and discoveries will also be shared internationally, helping position New Zealand as an industry innovator and key contributor to the SKA project.
New Zealand is a small country, but we are large participants in the SKA. By Reannz getting involved in this project, it allows NZ universities and researchers to participate in SKA science without needing to be physically based at the telescope sites.
This is a once-in-a-lifetime opportunity for New Zealand and the science community, enabling direct participation in the building of the largest scientific instrument in human history, as well as the opportunity to make their own discoveries using the data that is collected once the project goes live.
ID: What about any spin-offs for business and technology developers?
SC: The SKA project will use roughly enough optical fiber to wrap twice around the Earth, and the supercomputer being built will have the power of around 100 million PCs.
No doubt, this will result in a range of new technologies becoming available to the wider market, including new CPUs (central processing units) and more advanced green technology (cooling), as well as more complex algorithms to better manage code, leading to better cell phone reception, etc.
New Zealand is now in a prime position to take advantage of all of the advancements and discoveries made possible by the SKA. It is up to New Zealand to step up, have the courage to invest in this area of science while actively supporting the imagination of our brightest innovators to commercialise these advancements in ways that will help New Zealand and the world.
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Launching today: NASA's new satellite seeking "alien" Earths
Monday April 16, 2018. 03:05 PM , from BoingBoing
Today, SpaceX expects to launch a Falcon 9 rocket to deliver NASA's Transiting Exoplanet Survey Satellite (TESS) into orbit. Scientists expect TESS to find thousands of exoplanets by detecting when they pass in front of their host stars, briefly blocking the light of those suns.
“A few months after TESS launches, we will be able to point out the first ones of these familiar stars, which host planets that could be like ours,” says Cornell University astronomer Lisa Kaltenegger, director of the Carl Sagan Institute.
From Nadia Drake's excellent FAQ on TESS in National Geographic:
The search for life beyond Earth is necessarily constrained by what we know. Life as we don’t know it could be anywhere, and it doesn’t care that we haven’t deigned to imagine it yet. To help focus the hunt, astronomers are starting by looking for something familiar. And we know that at least once, life evolved on a warm, rocky planet orbiting a relatively stable star.
That being said, many of the stars TESS will scrutinize will be smaller and dimmer than our own: the cool, reddish M dwarfs that are the most common types of stars in the Milky Way. Planets orbiting these stars at a distance that’s neither too hot nor too cold for liquid water to exist are going to be snuggled in quite close—orbiting near enough to their stars for scientists to find them on months-long time scales.
In addition, the worlds TESS expects to find will be better situated for observations that could reveal whether alien metabolisms are churning away on their surfaces, beneath their seas, or in their clouds.
The launch is scheduled for 6:32pm EDT. Watch live on NASA TV along with other events throughout the day.
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The climate is changing due to heavy industry and artificial processes created by mankind. Over the last few decades, the climate has been severely impacted by increased emissions of CO2, leading to extreme weather events. In the case of the UK heatwaves, droughts, cold snaps, and flooding are occurring more frequently.
The United Kingdom is combatting the effects of climate change in many ways. Since all cities in the UK are affected by common problems, measures need to be taken to change the chronicle of these potentially life-threatening events. Even if the global incentive to limit temperature increase by 2 degrees, the weather patterns will differ and climate change will be severe.
When no action is taken and our planets annual average temperature increases by more than two degrees, the effects will be devastating. There will be a significant increase of ocean levels, volatility in river flow, water shortages, and extreme droughts.
As of today, the UK is a firm proponent of the 2015 Paris climate accords, and even before this accord was reached, it was taking measures to lessen carbon dioxide emissions. What’s more, the largest UK urban areas have plans to become energy independent by 2050.
London, Manchester, West Yorkshire, Glasgow, and the West Midlands are leading the way by introducing methods and becoming more climate-friendly. These five largest urban areas in the UK prepare their cities, and ultimately their citizens, for the effects of floods, heatwaves, and other extreme weather occurrences that will occur in the coming decades.A challenging task since the people and the authorities must work around high population density, spatial planning complications, and pollutant technologies.
GreenMatch has made this really cool infographic that shows how the climate effects for the five urban areas discussed. In addition to effects are the initiated measures listed to help resolve these problems.
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These numbers were first developed in hydrology by Robert E. Horton (1945) and Arthur Newell Strahler (1952, 1957); in this application, they are referred to as the Strahler stream order and are used to define stream size based on a hierarchy of tributaries. They also arise in the analysis of L-systems and of hierarchical biological structures such as (biological) trees and animal respiratory and circulatory systems, in register allocation for compilation of high-level programming languages and in the analysis of social networks. Alternative stream ordering systems have been developed by Shreve and Hodgkinson et al. A statistical comparison of Strahler and Shreve systems, together with an analysis of stream/link lengths, is given by Smart.
All trees in this context are directed graphs, oriented from the root towards the leaves; in other words, they are arborescences. The degree of a node in a tree is just its number of children. One may assign a Strahler number to all nodes of a tree, in bottom-up order, as follows:
- If the node is a leaf (has no children), its Strahler number is one.
- If the node has one child with Strahler number i, and all other children have Strahler numbers less than i, then the Strahler number of the node is i again.
- If the node has two or more children with Strahler number i, and no children with greater number, then the Strahler number of the node is i + 1.
The Strahler number of a tree is the number of its root node.
Algorithmically, these numbers may be assigned by performing a depth-first search and assigning each node's number in postorder. The same numbers may also be generated via a pruning process in which the tree is simplified in a sequence of stages, where in each stage one removes all leaf nodes and all of the paths of degree-one nodes leading to leaves: the Strahler number of a node is the stage at which it would be removed by this process, and the Strahler number of a tree is the number of stages required to remove all of its nodes. Another equivalent definition of the Strahler number of a tree is that it is the height of the largest complete binary tree that can be homeomorphically embedded into the given tree; the Strahler number of a node in a tree is similarly the height of the largest complete binary tree that can be embedded below that node.
Any node with Strahler number i must have at least two descendants with Strahler number i − 1, at least four descendants with Strahler number i − 2, etc., and at least 2i − 1 leaf descendants. Therefore, in a tree with n nodes, the largest possible Strahler number is log2 n + 1. However, unless the tree forms a complete binary tree its Strahler number will be less than this bound. In an n-node binary tree, chosen uniformly at random among all possible binary trees, the expected index of the root is with high probability very close to log4 n.
In the application of the Strahler stream order to hydrology, each segment of a stream or river within a river network is treated as a node in a tree, with the next segment downstream as its parent. When two first-order streams come together, they form a second-order stream. When two second-order streams come together, they form a third-order stream. Streams of lower order joining a higher order stream do not change the order of the higher stream. Thus, if a first-order stream joins a second-order stream, it remains a second-order stream. It is not until a second-order stream combines with another second-order stream that it becomes a third-order stream. As with mathematical trees, a segment with index i must be fed by at least 2i − 1 different tributaries of index 1. Shreve noted that Horton’s and Strahler’s Laws should be expected from any topologically random distribution. A later review of the relationships confirmed this argument, establishing that, from the properties the laws describe, no conclusion can be drawn to explain the structure or origin of the stream network.
To qualify as a stream a hydrological feature must be either recurring or perennial. Recurring (or "intermittent") streams have water in the channel for at least part of the year. The index of a stream or river may range from 1 (a stream with no tributaries) to 12 (globally the most powerful river, the Amazon, at its mouth). The Ohio River is of order eight and the Mississippi River is of order 10. Estimates are that 80% of the streams on the planet are first to third order headwater streams.
If the bifurcation ratio of a river network is low, then there is a higher chance of flooding, as the water will be concentrated in one channel rather than spread out, as a higher bifurcation ratio would indicate. The bifurcation ratio can also show which parts of a drainage basin are more likely to flood, comparatively, by looking at the separate ratios. Most British rivers have a bifurcation ratio of between 3 and 5.
Gleyzer et al. (2004) describe how to compute Strahler stream order values in a GIS application. This algorithm is implemented by RivEX, an ESRI ArcGIS 10.2.1 tool. The input to their algorithm is a network of the centre lines of the bodies of water, represented as arcs (or edges) joined at nodes. Lake boundaries and river banks should not be used as arcs, as these will generally form a non-tree network with an incorrect topology.
Other hierarchical systemsEdit
The Strahler numbering may be applied in the statistical analysis of any hierarchical system, not just to rivers.
- Arenas et al. (2004) describe an application of the Horton–Strahler index in the analysis of social networks.
- Ehrenfeucht, Rozenberg & Vermeir (1981) applied a variant of Strahler numbering (starting with zero at the leaves instead of one), which they called tree-rank, to the analysis of L-systems.
- Strahler numbering has also been applied to biological hierarchies such as the branching structures of trees and of animal respiratory and circulatory systems.
When translating a high-level programming language to assembly language the minimum number of registers required to evaluate an expression tree is exactly its Strahler number. In this context, the Strahler number may also be called the register number.
For expression trees that require more registers than are available, the Sethi–Ullman algorithm may be used to translate an expression tree into a sequence of machine instructions that uses the registers as efficiently as possible, minimizing the number of times intermediate values are spilled from registers to main memory and the total number of instructions in the resulting compiled code.
Associated with the Strahler numbers of a tree are bifurcation ratios, numbers describing how close to balanced a tree is. For each order i in a hierarchy, the ith bifurcation ratio is
where ni denotes the number of nodes with order i.
The bifurcation ratio of an overall hierarchy may be taken by averaging the bifurcation ratios at different orders. In a complete binary tree, the bifurcation ratio will be 2, while other trees will have smaller bifurcation ratios.It is a dimensionless number.
The pathwidth of an arbitrary undirected graph G may be defined as the smallest number w such that there exists an interval graph H containing G as a subgraph, with the largest clique in H having w + 1 vertices. For trees (viewed as undirected graphs by forgetting their orientation and root) the pathwidth differs from the Strahler number, but is closely related to it: in a tree with pathwidth w and Strahler number s, these two numbers are related by the inequalities
- w ≤ s ≤ 2w + 2.
The ability to handle graphs with cycles and not just trees gives pathwidth extra versatility compared to the Strahler number. However, unlike the Strahler number, the pathwidth is defined only for the whole graph, and not separately for each node in the graph.
- Main stem of a river, typically found by following the branch with the highest Strahler number
- Shreve, R.L., 1966. Statistical law of stream numbers. Journal of Geology 74, 17–37.
- Shreve, R.L., 1967. Infinite topologically random channel networks. Journal of Geology 75, 178–186.
- Hodgkinson, J.H., McLoughlin, S. & Cox, M.E. 2006. The influence of structural grain on drainage in a metamorphic sub-catchment: Laceys Creek, southeast Queensland, Australia. Geomorphology, 81: 394–407.
- Smart, J.S. 1968, Statistical properties of stream lengths, Water Resources Research, 4, No 5. 1001–1014
- Devroye & Kruszewski (1996).
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- Strahler, A. N. (1957), "Quantitative analysis of watershed geomorphology", Transactions of the American Geophysical Union, 38 (6): 913–920, Bibcode:1957TrAGU..38..913S, doi:10.1029/tr038i006p00913.
- Waugh, David (2002), Geography, An Integrated Approach (3rd ed.), Nelson Thornes. | <urn:uuid:b6574860-d9d0-4c44-959a-a23770d83c67> | 3.5 | 3,087 | Knowledge Article | Science & Tech. | 64.641117 | 95,525,215 |
More isn’t always better when it comes to DNA
Great, wonderful, wacky things can come in small genomic packages.
Credit: Enrique Ibarra-Laclette and Claudia Anahí Pérez-Torres.
Light micrograph of the bladder of the carnivorous bladderwort plant, Utricularia gibba. A new study finds that this marvelous plant houses more genes than several well-known species, such as grape, coffee or papaya — despite having a much smaller genome.
Credit: Enrique Ibarra-Laclette, Claudia Anahí Pérez-Torres and Paulina Lozano-Sotomayor.
Scanning electron micrograph of the bladder of Utricularia gibba, the humped bladderwort plant (color added). The plant is a voracious carnivore, with its tiny, 1-millimeter-long bladders leveraging vacuum pressure to suck in tiny prey at great speed.
That’s one lesson to be learned from the carnivorous bladderwort, a plant whose tiny genome turns out to be a jewel box full of evolutionary treasures.
Called Utricularia gibba by scientists, the bladderwort is a marvel of nature. It lives in an aquatic environment. It has no recognizable roots. It boasts floating, thread-like branches, along with miniature traps that use vacuum pressure to capture prey.
A new study in the scientific journal Molecular Biology and Evolution breaks down the plant’s genetic makeup, and finds a fascinating story.
According to the research, the bladderwort houses more genes than several well-known plant species, such as grape, coffee or papaya — despite having a much smaller genome.
This incredibly compact architecture results from a history of “rampant” DNA deletion in which the plant added and then eliminated genetic material at a very fast pace, says University at Buffalo Professor of Biological Sciences Victor Albert, who led the study.
“The story is that we can see that throughout its history, the bladderwort has habitually gained and shed oodles of DNA,” he says.
“With a shrunken genome,” he adds, “we might expect to see what I would call a minimal DNA complement: a plant that has relatively few genes — only the ones needed to make a simple plant. But that’s not what we see.”
A unique and elaborate genetic architecture
In contrast to the minimalist plant theory, Albert and his colleagues found that U. gibba has more genes than some plants with larger genomes, including grape, as already noted, and Arabidopsis, a commonly studied flower.
A comparison with the grape genome shows U. gibba’s genetic opulence clearly: The bladderwort genome, holding roughly 80 million base pairs of DNA, is six times smaller than the grape’s. And yet, the bladderwort is the species that has more genes: some 28,500 of them, compared to about 26,300 for the grape.
U. gibba is particularly rich in genes that may facilitate carnivory — specifically, those that enable the plant to create enzymes similar to papain, which helps break down meat fibers. The bladderwort is also rich in genes linked to the biosynthesis of cell walls, an important task for aquatic species that must keep water at bay.
“When you have the kind of rampant DNA deletion that we see in the bladderwort, genes that are less important or redundant are easily lost,” Albert says. “The genes that remain — and their functions — are the ones that were able to withstand this deletion pressure, so the selective advantage of having these genes must be pretty high.
“Accordingly, we found a number of genetic enhancements, like the meat-dissolving enzymes, that make Utricularia distinct from other species.”
Much of the DNA the bladderwort deleted over time was noncoding “junk DNA” that contains no genes, Albert says.
High gene turnover
The study included partners from UB, the Universitat de Barcelona in Spain, the Laboratorio Nacional de Genómica para la Biodiversidad (LANGEBIO) in Mexico and the Instituto de Ecología in Mexico.
To determine how the bladderwort evolved its current genetic structure, the team compared the plant to four related species. What they uncovered was a pattern of rapid DNA alteration.
As Albert explains, “When you look at the bladderwort’s history, it’s shedding genes all the time, but it’s also gaining them at an appreciable enough rate, permitting it to stay alive and produce appropriate adaptations for its unique environmental niche.”
In the realm of DNA gain, the study found that U. gibba has undergone three duplication events in which its entire genome was replicated, giving it redundant copies of every gene.
This fast-paced gene gain was balanced out by swift deletion. Evidence for this phenomenon comes from the fact that the plant has a tiny genome despite its history of genetic duplication. In addition, the plant houses a high percentage of genes that don’t have close relatives within the genome, which suggests the plant quickly deleted redundant DNA acquired through duplication events.
The study was supported by the National Science Foundation. It builds on the work of Albert and other team members, who reported in the journal Nature in 2013 that the bladderwort’s genome was comprised almost entirely of useful, functional genes and their controlling elements, in contrast to species like humans, whose genomes are more than 90 percent “junk DNA.”
Contact: Charlotte Hsu, email@example.com
University at Buffalo
Charlotte Hsu | newswise
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In the years after Columbus' voyage, burning of New World forests and fields diminished significantly – a phenomenon some have attributed to decimation of native populations by European diseases. But a new University of Utah-led study suggests global cooling resulted in fewer fires because both preceded Columbus in many regions worldwide.
"The drop in fire [after about A.D. 1500] has been linked previously to the population collapse. We're saying no, there is enough independent evidence that the drop in fire was caused by cooling climate," says the study's principal author, Mitchell Power, an assistant professor of geography at the University of Utah.
"The implication is that climate is a large-scale driver of fire. That's a key finding. Climate is driving fire on global and continental scales," says Power, who also is curator of the Garrett Herbarium at the Natural History Museum of Utah, which is part of the University of Utah.
The new study analyzed worldwide charcoal samples spanning 2,000 years. It will be published online during August in the journal The Holocene, which is the name of the geological epoch covering roughly the last 11,500 years of Earth's history. It was funded by the National Science Foundation and the Natural History Museum of Utah.
The study deals with the Little Ice Age, a period when Earth's climate cooled, causing New York Harbor to freeze over in 1780, among other effects. Estimates of when the Little Ice Age started range from the 1200s to the 1500s. It ended in the early 1800s. Possible causes include some combination of increased dust from volcanic eruptions, decreased solar activity, and changes in circulation of the ocean and atmosphere.
"The decrease in fire on a very large scale – globally and in the Americas – was controlled by this cooling climate, which began prior to the population collapse, and climate alone is sufficient to explain large scale changes in burning," says Power.
"In a cooler atmosphere, you tend to get reduced convection, so you get reduced thunderstorms and ignition from lightning," he says. "Cooler climate also tends to maintain high levels of fuel moisture and soil moisture."
Today, warming climate and drought have been tied to increasing fires in the U.S. West and elsewhere. "In a world where climate is rapidly changing we need to pay more attention to this relationship between climate and fire," Power says
Power conducted the study with 19 other scientists, including paleoecologist Frank Mayle at the University of Edinburgh, U.K., and climatologist Patrick Bartlein at the University of Oregon. Other coauthors – who provided charcoal data or samples – are from University of Wisconsin, Madison and Oshkosh; Northern Arizona University; University of Gottingen, Germany; Canadian Forest Service; University of Montpellier, France; University of Bern, Switzerland; University of Calgary, Canada; University of Tennessee; Virginia Tech; University of North Carolina; University of Chile; Laval University, Quebec; Fordham College, New York; and Central Washington University.Cooling Climate or Population Collapse?
"All these people died abruptly – Mayans, Incas, Aztecs and down in Patagonia – they were all affected," he adds. "Agriculture was sharply reduced. Landscapes that had been cleared for agriculture started a process of plants growing back and infilling those abandoned fields. In terms of greenhouse gases, when you change from maintained cropland to woodlands, plants take up more carbon dioxide and there is less in the atmosphere. This has been pointed to as one mechanism for causing the Little Ice Age."
Power agrees population collapse may have led to reduced biomass burning in some local regions of the Americas. But the new study indicates the reduction in fire was actually global and began before Columbus in most areas, suggesting the Little Ice Age triggered most of the reduction in burning – not the other way around, Power says.
"If you look at independent climate records, cooling from the Little Ice Age was happening about 200 years before the population collapse," or about A.D. 1300, he says.
Power notes there is room for debate because the Little Ice Age varied in time and space, and didn't affect all parts of the world equally, although most places cooled.A Record of Fire Left in Charcoal
"Whatever was burning, we see a record of that fire in lake sediments, from either aerial transport or erosion" of burned material, Power says.
Power manages the Global Charcoal Database that compiles data from all the existing studies that date charcoal samples and describe where they came from. The new study included 498 existing charcoal records and 93 new samples.
"We have gone back in and calculated the ages of all these charcoal samples," except for some dated independently in other recent studies, and then used recent radiocarbon dating calibrations to make sure all data are consistent, Power says.
"Greater than 80 percent of biomass burning records show a decline post-1500 in the Americas, he says. The other 20 percent may be from areas that were still fire-prone despite cooling or that simply had burning declines for which there are inadequate charcoal samples, he adds.The study compared the charcoal records with previously published ancient climate records and population reconstructions. It found:
Clumping all the charcoal data in two groups – from the Americas or the Eastern Hemisphere – shows that in the Americas, biomass burning declined between 1500 and 1650 and stayed at a minimum until 1700, the same time as the peak of the Little Ice Age. That period was the lowest level of burning in the past 6,000 years.
In the Eastern Hemisphere, there was a prominent decline in burning that began about 1400 – well before the population collapse in the Americas. Power says cooling also started about a century earlier in the Eastern Hemisphere than in the Americas – more evidence cooling caused reduced burning. There was no parallel population collapse large enough to explain the reduction in burning, although a small downward blip in burning is noted in Europe around the time of the bubonic plague or Black Death.
In tropical Middle America – the Caribbean Basin, Mexico and Central America – climate cooling starting around 1350, when burning also begins to decline. Population collapse didn't begin until around 1500.
In tropical South America, climate changed around 1350 to 1400. There is debate whether it warmed or cooled. The population collapsed after 1500. Power says neither climate nor population strongly influenced post-Columbian biomass burning in that region, which declined only subtly and not until 1700. It also is possible the population that collapsed didn't use fire very much in agriculture – something a recent study coauthored by Power found in French Guiana.
In southern South America, ice-core and tree-ring growth studies show cooling began about 1450, well before an abrupt decline in burning in 1550. That would seem to support the theory that population collapse reduced burning – except that the region had little population, certainly not enough for any decline to trigger a reduction in burning.Ice cores from Greenland show cooling started about 1450, and fire started to decline about 1500, according to charcoal for boreal Canada and the western United States. Cooling and reduced burning stopped about 1800. Despite the 50-year lag, Power says that is more evidence tying climate cooling to reduced biomass burning, particularly since the region had relatively few people at the time.
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The new research effort expands past studies in the Gulf of Maine and builds on data collected during the historic 2005 red tide, which led to closure of both nearshore shellfish beds and offshore beds in federal waters out to Georges Bank. The toxicity also extended for the first time to the islands of Martha’s Vineyard and Nantucket.
The Gulf of Maine (GoM) and its adjacent southern New England shelf is a vast region with extensive shellfish resources, large portions of which are frequently contaminated with paralytic shellfish poisoning (PSP) toxins produced by the dinoflagellate Alexandrium fundyense. The 2005 outbreak caused millions of dollars in economic damage, but monitoring programs and cooperation among federal, state and local officials, scientists, and shellfishermen prevented any reported cases of illness from people eating contaminated shellfish.
“As a result of the 2005 bloom and the closures in federal waters offshore and on the Cape and Islands, we realized we needed to expand efforts and develop a full, regional-scale understanding of Alexandrium fundyense blooms,” lead investigator Don Anderson of WHOI said. “We don’t understand the linkages between bloom dynamics and toxicity in waters near shore versus the offshore, nor do we know how toxicity is delivered to the shellfish in those offshore waters. An additional challenge is the need to expand modeling and forecasting capabilities to include the entire region, and to transition these tools to operational and management use.”
Anderson said the information and new technologies gained from the project will help managers, regulators and the shellfish industry to fully utilize and effectively manage both nearshore and offshore shellfish resources, and could lead to harvesting of the offshore surfclam and ocean quahog beds on Georges Bank and Nantucket Shoals, which have an estimated potential value of more than $50 million a year. The program should also provide information crucial to the development of a roe-on scallop industry in those waters - a product which is presently restricted because of toxin that accumulates in the roe.
GOMTOX will utilize a combination of large-and small-scale survey cruises, autonomous gliders, moored instruments and traps, drifters, satellite imagery and numerical models. Researchers will incorporate field observations into a suite of numerical models of the region for hindcasting and forecasting applications for both near shore and offshore shellfish resources.
In addition to WHOI researchers, scientists participating in GOMTOX represent Canada’s Department of Fisheries and Oceans, NOAA’s Northeast Fisheries Science Center, the Canadian National Research Council, the U.S. Food and Drug Administration, University of Maine, University of Massachusetts, and the Stellwagen Bank National Marine Sanctuary.
“We will be working closely with federal, state and local officials, resource managers and shellfishermen to synthesize results and disseminate the information and technology,” Anderson said. “Our ultimate goal is to transition scientific and management tools to the regulatory community for operational use. This project covers the entire Gulf fo Maine, including the Bay of Fundy, so there are many affected user groups, communities, and industries who stand to benefit.”
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Gene Tool Will Improve Environmental Arsenic Studies
Dr. Babur Mirza takes a groundwater sample from a well in Logan, Utah. Credit: Utah State University
Environmental engineers are making it easier to identify the bacterial species responsible for releasing a form of arsenic that contaminates the water supplies of millions of people worldwide.
A team of Utah State University College of Engineering researchers developed a new primer – a tool used in DNA amplification – that simplifies the process of identifying bacteria found in soil and groundwater samples. Of interest are the bacteria species equipped with arsenate reductase genes. The genes enable bacteria to transform naturally occurring arsenic into a more toxic version of the element. The team’s findings were published Feb. 1 in Applied and Environmental Microbiology – a leading journal, covering topics in biotechnology, microbial ecology, food microbiology and industrial microbiology.
The authors explain that various bacteria transform, or reduce, arsenic V – known as arsenate – into arsenic III – known as arsenite. Arsenite is more toxic to humans and is more mobile, meaning it moves through the environment more easily and can infiltrate groundwater.
Researchers say a better understanding of the microbial ecosystems that release arsenite is an important first step in reducing the prevalence of arsenic contamination in groundwater.
“Arsenic contamination is one of the biggest problems in drinking water all over the world,” said Dr. Babur Mirza, a researcher at USU’s Utah Water Research Lab and lead author on the study. “This new primer makes it easier for us to see which species of bacteria are present in a sample and whether they have the gene that we’re looking for.”
The new primer – a short strand of DNA that targets the arsenate reductase gene – helps researchers identify which bacteria in a sample have the genes. Without this primer, researchers had to first grow the bacterial cells in a laboratory before extracting their DNA and amplifying the gene. Such steps often reduced microbial diversity and led to biased results.
“Now we can simply add the primer into the reaction and we get quantifiable copies of the reductase genes,” said Mirza. “The copied genes show us which bacteria species are in the sample and tell us new information about the diversity of arsenate-reducing microorganisms.”
As part of the study, the team, led by co-author Dr. Joan McLean, pulled groundwater samples from 20 privately owned wells located in Northern Utah’s Cache County. The results showed that 20 percent of the wells surveyed had arsenate and arsenite concentrations above the drinking water limit of 10 micrograms per liter. Researchers then tested whether the samples containing high arsenite concentrations also had an abundance of the arsenate reductase genetic material. Not surprisingly, they found a direct match.
“We observed a significant correlation between reductase gene abundance and arsenite concentrations in the groundwater samples,” said Mirza. “What this means is that wherever we find arsenite, we can expect to find microbes with arsenate reductase genes and vice versa.”
Mirza said the new primer successfully amplified the reductase genes and made it possible for his team to see a broad diversity of arsenate-reducing microorganisms. He said the new primers will be useful for studying bacteria in a range of environments.
The authors say there are various implications to the study. McLean, a research associate professor in USU's Department of Civil and Environmental Engineering, said a complete picture of the diversity of arsenate-reducing bacteria in a particular environment could lead to improved land use practices and awareness of human activities that may exacerbate the problem.
“With this new information describing the diversity of arsenic-reducing microorganisms, we are further exploring relationships between these organisms and their biogeochemical environments that result in arsenic contamination of groundwater.”
This article has been republished from materials provided by Utah State University. Note: material may have been edited for length and content. For further information, please contact the cited source.
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A wrinkle ridge is a type of feature commonly found on lunar maria. These features are low, sinuous ridges formed on the mare surface that can extend for up to several hundred kilometers. Wrinkle ridges are tectonic features created when the basaltic lava cooled and contracted. They frequently outline ring structures buried within the mare, follow circular patterns outlining the mare, or intersect protruding peaks. They are sometimes called veins due to their resemblance to the veins that protrude from beneath the skin. These are found near craters.
Wrinkle ridges are named with the Latin designation dorsum (plural dorsa). The standard IAU nomenclature uses the names of people to identify wrinkle ridges on the Moon. Thus the Dorsa Burnet are named for Thomas Burnet, and the Dorsum Owen is named after George Owen of Henllys.
Wrinkle ridges in Hesperia Planum, Mars, as seen by Viking The wrinkle ridges go in different directions so compressional forces may have changed direction over time.
Trough cutting a wrinkle ridge, as seen by HiRISE under HiWish program Location is the Coprates quadrangle, Mars.
Wrinkle ridges can also be found on Mars, for example in Chryse Planitia, as well as on several of the asteroids that have been visited by spacecraft, as well as Mercury, and a couple of moons of Jupiter and Saturn. Although several hypotheses have been advanced as causes of Martian wrinkle ridges, today they are generally considered to be of tectonic origin. They involve folding and faulting. They are evidence of compressional stresses in Mars’ crust. The stress created a crack (fault) where one side was pushed on top of the other side, also known as a thrust fault.
|Wikimedia Commons has media related to Wrinkle ridges.|
- Kieffer, H, B. Jakosky, C. Snyder, M. Matthews (eds.). 1992. Mars. University of Arizona Press.
- Golombek, M. P., F. S. Anderson, and M. T. Zuber (2001), Martian wrinkle ridge topography: Evidence for subsurface faults from MOLA, J. Geophys. Res., 106, 23,811–23,821, doi:10.1029/2000JE001308.
- Montési, L. G. J., and M. T. Zuber (2003), Clues to the lithospheric structure of Mars from wrinkle ridge sets and localization instability, J. Geophys. Res., 108(E6), 5048, doi:10.1029/2002JE001974.
- Watters, T. R. (1988), Wrinkle Ridge Assemblages on the Terrestrial Planets, J. Geophys. Res., 93(B9), 10,236–10,254, doi:10.1029/JB093iB09p10236.
- Watters, et al., Evidence of Recent Thrust Faulting on the Moon Revealed by the Lunar Reconnaissance Orbiter Camera. Science 20 August 2010: 936-940. doi:10.1126/science.1189590 | <urn:uuid:e5e57a48-f7e5-40a3-bdd4-d5fc61ee7afb> | 4.09375 | 686 | Knowledge Article | Science & Tech. | 63.923571 | 95,525,376 |
In a discovery that raises further concerns about the future contribution of Antarctica to sea level rise, a new study finds that the western part of the ice sheet is experiencing nearly twice as much warming as previously thought.
The temperature record from Byrd Station, a scientific outpost in the center of the West Antarctic Ice Sheet (WAIS), demonstrates a marked increase of 4.3 degrees Fahrenheit (2.4 degrees Celsius) in average annual temperature since 1958—that is, three times faster than the average temperature rise around the globe.
This temperature increase is nearly double what previous research has suggested, and reveals—for the first time—warming trends during the summer months of the Southern Hemisphere (December through February), said David Bromwich, professor of geography at Ohio State University and senior research scientist at the Byrd Polar Research Center.
The findings were published online this week in the journal Nature Geoscience.
"Our record suggests that continued summer warming in West Antarctica could upset the surface mass balance of the ice sheet, so that the region could make an even bigger contribution to sea level rise than it already does," said Bromwich.
"Even without generating significant mass loss directly, surface melting on the WAIS could contribute to sea level indirectly, by weakening the West Antarctic ice shelves that restrain the region's natural ice flow into the ocean."
Andrew Monaghan, study co-author and scientist at the National Center for Atmospheric Research (NCAR), said that these findings place West Antarctica among the fastest-warming regions on Earth.
"We've already seen enhanced surface melting contribute to the breakup of the Antarctic's Larsen B Ice Shelf, where glaciers at the edge discharged massive sections of ice into the ocean that contributed to sea level rise," Monaghan said. "The stakes would be much higher if a similar event occurred to an ice shelf restraining one of the enormous WAIS glaciers."
Researchers consider the WAIS especially sensitive to climate change, explained Ohio State University doctoral student Julien Nicolas. Since the base of the ice sheet rests below sea level, it is vulnerable to direct contact with warm ocean water. Its melting currently contributes 0.3 mm to sea level rise each year—second to Greenland, whose contribution to sea level rise has been estimated as high as 0.7 mm per year.
Due to its location some 700 miles from the South Pole and near the center of the WAIS, Byrd Station is an important indicator of climate change throughout the region.
In the past, researchers haven't been able to make much use of the Byrd Station measurements because the data was incomplete; nearly one third of the temperature observations were missing for the time period of the study. Since its establishment in 1957, the station hasn't always been occupied. A year-round automated station was installed in 1980, but it has experienced frequent power outages, especially during the long polar night, when its solar panels can't recharge.
Bromwich and two of his graduate students, along with colleagues from NCAR and the University of Wisconsin-Madison, corrected the past Byrd temperature measurements and used corrected data from a computer atmospheric model and a numerical analysis method to fill in the missing observations.
Aside from offering a more complete picture of warming in West Antarctica, the study suggests that if this warming trend continues, melting will become more extensive in the region in the future, Bromwich said.
While the researchers work to fully understand the cause of the summer warming at Byrd Station, the next step is clear, he added.
"West Antarctica is one of the most rapidly changing regions on Earth, but it is also one of the least known," he said. "Our study underscores the need for a reliable network of meteorological observations throughout West Antarctica, so that we can know what is happening—and why—with more certainty."
Explore further: More ice loss through snowfall on Antarctica | <urn:uuid:6c6398ca-29a0-4404-b2c1-dd06c97cd193> | 3.890625 | 779 | News Article | Science & Tech. | 31.348091 | 95,525,405 |
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By: GM Mapstone
302 pages, Figs, tabs
This important work updates siphonophore taxonomy for the first time in 40 years, applying and extending the new holistic terminology recently introduced by other authors and providing full synonymies for many common species. Divided into 10 sections, it includes general sections on systematics, life cycles, and ecology; detailed descriptions and diagnoses for 37 species collected from Canadian Pacific waters; relevant genus and family diagnoses; and three keys. With more than 60 figures (including many camera lucida line drawings), this book should prove invaluable to taxonomists, deep ocean researchers, and evolutionary geneticists working on cnidarian phylogenetic relationships.
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|CNIDARIA : ACTINIARIA : Edwardsiidae||SEA ANEMONES AND HYDROIDS|
Description: The column of this burrowing sea anemone is elongated and worm-like; divided into scapus and scapulus. The scapus has a soft, adherent cuticle, and a naked rounded base. The tentacles are very long when fully expanded, 16 in number, arranged in two distinct cycles of 8. Length of column up to 80mm when fully extended, span of tentacles to 40mm. The disc is patterned with white and maroon, the tentacles are transparent, unspotted, with a white ring at the base and sometimes a little white coloration near the tip.
Habitat: Burrows in mud or sandy mud; when expanded only the disc and tentacles protrude above the substrate. Occurs in sheltered situations in shallow water.
Distribution: Only known from the vicinity of Valentia Island, SW Ireland.
Similar Species: Edwardsia claparedii, is variable in colour and may have only white markings on the disc but has spots and markings on the tentacles as well as the disc.
Key Identification Features:
Distribution Map from NBN: Interactive map : National Biodiversity Network mapping facility, data for UK.
WoRMS: Species record : World Register of Marine Species.
|Picton, B.E. & Morrow, C.C. (2016). Edwardsia delapiae Carlgren & Stephenson, 1928. [In] Encyclopedia of Marine Life of Britain and Ireland. |
http://www.habitas.org.uk/marinelife/species.asp?item=D13430 Accessed on 2018-07-19
|Copyright © National Museums of Northern Ireland, 2002-2015| | <urn:uuid:22a592c8-b6a6-4b40-a71f-de2f85dfd157> | 2.6875 | 374 | Knowledge Article | Science & Tech. | 46.596386 | 95,525,430 |
Species Detail - Desmoulin's Whorl Snail (Vertigo (Vertigo) moulinsiana) - 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).
Vertigo (Vertigo) moulinsiana
Desmoulin's Whorl Snail
Protected Species: EU Habitats Directive || Protected Species: EU Habitats Directive >> Annex II || Protected Species: Wildlife Acts || Threatened Species: Endangered
7 March (recorded in 2005)
25 November (recorded in 1998)
National Biodiversity Data Centre, Ireland, Desmoulin's Whorl Snail (Vertigo (Vertigo) moulinsiana), accessed 19 July 2018, <https://maps.biodiversityireland.ie/Species/123616> | <urn:uuid:aa461825-e331-4e1e-868f-a68228652dfa> | 2.78125 | 217 | Structured Data | Science & Tech. | 21.154286 | 95,525,433 |
10 locations with unusual meteorological phenomena
There are rare locations in the world, where one can experience unique, highly unusual phenomena related to meteorology.
Below you see unique list of 10 such locations. Some of these phenomena have been explained, but for some explanation is still needed… or – may be these are just legends.
All these monuments belong to the category of Sites of meteorological phenomena.
1. Catatumbo Lightning – most persistent thunderstorm
The most persistent and most spectacular thunderstorm in the world is Catatumbo Lightning. This is nearly continuous thunderstorm with up to 20,000 flashes of lightning per night, seen 140 – 160 nights per year and lasting approximately 10 hours long. It produces approximately 10% of tropospheric ozone in the world.
Contrary to usual thunderstorms Catatumbo Lightning always is in the same place and can be observed 140 – 160 nights per year, 10 hours long.
This inaudible thunderstorm resembles a giant strobe light with up to 20,000 flashes per night. Thanks to clear sky lightnings are visible very far away in the Caribbean – even in the 500 km distant island of Aruba. Thus the second name of this phenomena is Maracaibo Lighthouse. Hardly any human built lighthouse can beat the power of it!
We do not know when started the Catatumbo Lightning started but this phenomenon has become a part of the tales of indigenous people.
2. Chir Batti
Strange lights are seen over the vast plains south from Rann of Kutch in Gujarat, India. These "ghost lights" are not explained and represent round or pear shaped balls of fire, glowing like mercury lamps. They are floating above the ground, in 0.6 – 3 m height. Sometimes they are moving around slowly, sometimes – fast as arrows.
Especially weird is the interaction of lights with visitors. If one walks away, Chir Batti happen to follow him. Around Kiro hill they may follow up to the nearby Fulay village. But it is never heard that balls of light have done any harm.
Hessdalen became internationally renowned when in December 1981 something unusual started – some 15 – 20 times per week spooky, big and bright balls of light appeared above the valley. Sometimes these balls were standing still for more than one hour, sometimes they were slowly floating around. There were times when the light moved very fast. At one time radar fixed 8 500 m/s fast movement: 8 – 9 times faster than the fastest airplane of the world.
Weird illuminations of Hessdalen continued nearly every night until summer 1984 and lots of tourists came here to see this marvel. Then the activity decreased and now the lights are observed some 10 – 20 times per year. Scientific laboratories have been installed and the lights are intensely researched.
Tajikistan, Kuhistoni-Badakhshon Autonomus Province
In order to reach the Tarim basin, the caravans of the Great Silk Road had a choice – to walk through the dry flats in the north-eastern part of Pamir. But this was tough choice – in these weird flats countless dust devils rise. They reach the strength of tornadoes and are very dangerous – there are reports about camels with all their burdens lifted by winds. People believed that these are real, fearsome spirits – jinns.
No wonder that for centuries the ancient road was lined with corpses of dead pack-animals. Also nowadays Markansu desert leaves sombre feeling.
Australia, Queensland and North Australia
This is the only place in the world, where extremely unusual weather phenomenon – morning glory can be observed on a regular basis.
Morning glory happens early in the morning, when above the surprised spectators "roll" over one or few roll clouds – long, low, narrow clouds resembling giant, up to 1,000 km long ropes.
Thailand, Nongkhai and Laos, Vientiane Province
Weird things are happening some 70 – 100 kilometers downstream from the Vientiane – capital of Laos. In the nights from the muddy waters of Mekong river appear red glowing balls which quickly rise up in the air and disappear without noise (some, who manage to be close to the lights, report silent hiss). These mysterious sparkles are small, but sometimes they reach a size of an basketball.
These are not some ghosts seen by occasional people and questioned by majority. Ghost fireballs of Mekong have been seen by thousands of people, photographed and captioned on movies and, after all, investigated by scientists looking for the explanation of this interesting phenomenon.
Finland, Southern Savonia
There was a time when locals living around Lake Paasselkä (earlier – Paasivesi) did not turn much attention to the lights hovering above this large lake. Paasselkä Devil was just a play of spirits, who should care about them?
Nowadays, when we don’t believe in spirits, this light phenomena is very intriguing. It is observed rather often nowadays as well.
Paasselkä Devil looks like a ball of bright light howering above the lake. The light is very bright, much more powerful than the distant lights of car headlamps, driving along the lake.
It can be calm, resembling a bright lantern – but light might start to move very quickly.
Sometimes these lights behave as if they have their own will. They might follow the boats of fisherman, it has been also observed that lights evade from the beam of torch.
8. Poás Volcano and Laguna Caliente – site with the most acid rain
Costa Rica, Alajuela
Around the acid crater lake of Poás Volcano the acidity of fog and rain is around 2.0 of pH and may be even less. As a result around the crater and to the west from it there has formed some 3.5 km long and 1 km wide, lifeless, naked scar surrounded by jungle.
Effects of the volcanic acid rain extend far beyond this scar. In vicinity the farm equipment, cars and home utensils become rusty, roofs of the buildings are damaged. Often tourists have been rescued from the nature trails to avoid potential health problems due to acid fog – sometimes tourists have been running out of the fog coughing and with runny eyes.
There is mysterious lake in the magnificent Gharval Himalaya – Roopkund. For more than 1000 years around the lake lie several hundreds of dead people which most likely died in an extreme hailstorm.
Somewhere around 850 AD here was killed a large group of local and foreign piligrims heading towards Nanda Devi shrine. According to a legend they were punished by Goddess Nanda Devi for desecration of this sacred spot of Himalaya.
10. Yoro Fish Rain
Near Yoro town there happens a heavy rain in May – July. That would be nothing too special – but after this rain countless small, living fishes are left jumping in the fields as if they have fallen from the sky.
As the storm leaves, people of Yoro pick up baskets and run out to the swampy meadows of La Pantanal at the foot of extinct volcano El Mal Nombre (Bad Word). Hundreds and even thousands of jumping, live fish are found in the wet meadows as if fallen from the sky during the storm. People collect the fish to bring it home and eat – fish is told to have specific taste, different from the taste of common fish.
Map of the top 10 locations with unusual meteorological phenomena
David Stevenson’s new book links the meteorology of the Earth to that of other planets, stars, and clusters of galaxies, showing the similarities and differences between terrestrial weather and that of weather on other worlds. Because Earth is not unique in having weather, there is much to learn from other planets with atmospheres that show the movement of energy from hotter to colder areas. | <urn:uuid:d79dd76a-e220-415a-ab61-fd8e14e85ba9> | 3.03125 | 1,632 | Listicle | Science & Tech. | 51.380029 | 95,525,437 |
NASA's TESS Mission Will Find Thousands of New Planets
During its 2 years survey, the NASA’s Transiting Exoplanet Survey Satellite (TESS) will search for planet's "ranging from Earth-sized to giants larger than Jupiter," according to NASA's Goddard Space Flight Center. Credit: NASA's Goddard Space Flight Center
On Monday, April 16, the Transiting Exoplanet Survey Satellite (TESS) will launch from Cape Canaveral Air Force Station in Florida. NASA's new exoplanet hunter will train its sights on nearer, brighter stars than its predecessors did. If TESS lives up to scientists' predictions, it could energize our search for life in the cosmos.
When the Kepler space telescope launched in 2009, scientists didn't know what fraction of stars hosted planets. The Kepler mission was a statistical exploration looking to see how frequently planets occur around stars, Harvard astronomer David Latham told Space.com. "One of the big surprises from Kepler was to find this whole population of planets with sizes between that of Neptune and Earth — and there aren't any in our solar system, zero — and they're everywhere out there," said Latham, who's worked on the Kepler project for nearly 20 years.
"Kepler is what made us become aware that planets are as common as telephone poles," SETI Institute astronomer Seth Shostak told Space.com."But the stars that Kepler was staring at for four years … they were all somewhere between 500 and 1,500 light-years away." TESS will survey the local neighborhood for planets like Earth. [NASA's TESS Exoplanet-Hunter in Pictures]
TESS is designed to find planets orbiting nearby stars spread across the sky, astrophysicist and pioneering exoplanet researcher Sara Seager at the Massachusetts Institute of Technology told Space.com. The satellite is not specifically intended to look for planets that can support life, but it can find planets orbiting in the habitable zone of small stars, said Seager, who serves as a deputy science director on TESS.
TESS will find signals of planet candidates, Seager said. A lot of follow-up work will go into determining whether these candidates are truly planets, rather than binary stars, artifacts in the data or something else. Once this is accomplished, deeper investigation can begin. Unlike with Kepler, the stars TESS examines will be bright enough and close enough to allow detailed follow-up studies with large ground telescopes, the Hubble Space Telescope and the upcoming
James Webb Space Telescope.
New NASA Planet Finder TESS To Have Unusual Orbit
The Transiting Exoplanet Survey Satellite's (TESS) will orbit the Earth twice "every time the Moon orbits once," according to NASA's Goddard Space Flight Center. Credit: NASA's Goddard Space Flight Center
The amount of starlight a planet blocks tells astronomers the world's size, while the frequency with which the planet passes in front of its star indicates the world's orbital period, said Shostak. Scientists can determine the planet's mass by using the Doppler effect to measure the wobble the planet induces on its star. And mass divided by size equals density, so astronomers can determine whether they're looking at a puffy ball of gas or a solid chunk of rock.
What's more, these planets are close enough for other telescopes to peer inside their atmospheres. When a planet transits its star, some of the starlight passes through the planet's atmosphere before reaching Earth. Different gases absorb different wavelengths of light, and scientists can determine the composition of the planet's atmosphere by analyzing the spectrum of this light using more-powerful observatories. [7 Ways to Discover Alien Planets]
"Twenty years ago, if you told me that we were going to do this kind of spectroscopy of atmospheres of planets around other stars, I would have said you're crazy," said Latham. "Now, we're doing it."
Scientists are looking for signatures of life, byproducts that organisms might emit into the atmosphere. "The first thing is we're looking for water vapor," Seager said, "because all life, as we know it, needs liquid water. And water vapor is a sign of surface water."
"After water, oxygen would be fantastic. Oxygen is our best biosignature gas on Earth," Seager said, so we’re looking for what we know. "After that, we have lots of gases we're interested in, but mostly in space were looking for gases that don't belong that are there in high quantities, enough to really be detected from far away." [The Drake Equation Revisited: Interview with Planet Hunter Sara Seager]
NASA’s Planet Finder TESS Will Study 85 Percent of Sky - How?
The Transiting Exoplanet Survey Satellite (TESS) will use its 4 cameras to deliver data on 350 times more of the sky than NASA’s Kepler mission. Credit: NASA Goddard Space Flight Center
On the other hand, scientist may overlook signs of life that is radically different from us. "It's a little bit like the drunk looking for his keys — he looks under the lamppost, because that's where he can see them," Latham said. "We look for life that is similar to our own, because we think we understand the organic chemistry involved and so we think we know how to interpret [evidence for it]."
The search for intelligent life is guided by the Drake equation, a formula devised by astronomer Frank Drake to estimate the likelihood of receiving signals from intelligent civilizations. The terms of the equation begin with the number of stars in our galaxy and proceed to the number of civilizations actively broadcasting their presence into space. Kepler mostly firmed up the fraction of stars that have planets. The TESS mission will enrich our understanding of how many planets could support life, and even the fraction of those planets where life may actually occur, Seager explained, constraining the equation further.
"Thirty years ago,if you ask[ed] people, 'Do you think there are a lot of planets out there?' most people who knew anything about astronomy would say, 'Yeah, probably there are.' But nobody knew," said Shostak. With Kepler, researchers discovered that the universe is littered with planets. "For the first time in 300,000 years, Homo sapiens
had found planets around other stars," he said.
Shortly thereafter, scientists began to get enough data to hypothesize that many of those planets might be habitable. Over the past quarter-century, science has increasingly led scientists to believe that the existence of life may not be a miracle after all, Shostak said. And he said he sees no evidence that this trend will stop.
TESS will lead the way for a wealth of discoveries and deepen our understanding of many phenomena in the cosmos. "There's technical astrophysical issues that will interest a lot of the scientists in the community," said Latham, "but I think that the question that is going to catch the attention of the educated public is this big one: Are we alone?"
Visit Space.com Monday, April 16 for complete coverage of NASA's TESS mission launch. A live webcast on the launch begins at 6 p.m. EDT (2200 GMT). | <urn:uuid:952b1af2-cb82-4c26-b0a0-9e9b564fe9b3> | 3.515625 | 1,487 | Content Listing | Science & Tech. | 46.440428 | 95,525,454 |
In biology, a protein's shape is key to understanding how it causes disease or toxicity. Researchers who use X-rays to takes snapshots of proteins need a billion copies of the same protein stacked and packed into a neat crystal.
X-ray free-electron lasers can create images (left) that accurately reflect the known structure of proteins determined by conventional methods (right), in this case, three bacteriorhodopsin proteins.
Now, scientists using exceptionally bright and fast X-rays can take a picture that rivals conventional methods with a sheet of proteins just one protein molecule thick.
Using a type of laser known as XFEL, the technique opens the door to learning the structural details of almost 25 percent of known proteins, many of which have been overlooked due to their inability to stack properly. The team of researchers led by the Department of Energyfs Pacific Northwest and Lawrence Livermore National Laboratories report their results with this unique form of X-ray diffraction in the March issue of the International Union of Crystallography Journal.
"In this paper, we're proving it's possible to use an XFEL to study individual monolayers of protein," said PNNL microscopist James Evans. "Just being able to see any diffraction is brand new."
Evans co-led the team of two dozen scientists with LLNL physicist Matthias Frank. The bright, fast X-rays were produced at the Linac Coherent Light Source at SLAC National Accelerator Laboratory in Menlo Park, Calif., the newest of DOEfs major X-ray light source facilities at the U.S. National Laboratories. LCLS, currently the worldfs most powerful X-ray laser, is an X-ray free-electron laser. It produces beams millions of times brighter than earlier X-ray light sources.
Coming in at around 8 angstrom resolution (which can make out items a thousand times smaller than the width of a hair), the proteins appears slightly blurry but match the expected view based on previous research. Evans said this level of clarity would allow researchers, in some cases, to see how proteins change their shape as they interact with other proteins or molecules in their environment.
To get a clearer view of protein monolayers using XFEL, the team will need to improve the resolution to 1 to 3 angstroms, as well as take images of the proteins at angles, efforts that are currently underway.
Not Your Family's Crystal
Researchers have been using X-ray crystallography for more than 60 years to determine the shape and form of proteins that form the widgets and gears of a living organism's cells. The conventional method requires, however, that proteins stack into a large crystal, similar to how oranges stack in a crate. The structure of more than 80,000 proteins have been determined this way, leading to breakthroughs in understanding of diseases, pathogens, and how organisms grow and develop.
But many proteins found in nature do not stack easily. Some jut from the fatty membranes that cover cells, detecting and interacting with other cells and objects, such as viruses or bacteria, in the surrounding area. These proteins are not used to having others of their kind stack on top. These so-called membrane proteins make up about 25 percent of all proteins, but only 2 percent of proteins that researchers have determined structures for.
Researchers in the last decade have been pursuing the idea that one sheet of proteins could be visualized if the X-rays were bright enough and flashed on and off quickly enough to limit the damage. Two years ago, scientists demonstrated they could use XFEL technology on crystals of proteins about 15 to 20 sheets thick.
Evans, Frank and their team wanted to push this further. The team worked on a way to create one-sheet-thick crystals of two different proteins -- a protein called streptavidin and a membrane protein called bacteriodopsin. The structures of both proteins are well-known to scientists, which gave the team something to compare their results to.
The team shined the super-bright X-rays for a brief moment -- about 30 femtoseconds, a few million billionths of a second -- on the protein crystals. They created so much data in the process that it took them more than a year to analyze all of it.
The resulting images look like the known structures, validating this method. Next, the researchers will try to capture proteins changing shape as they engage in a chemical reaction. For this, even shorter flashes of X-rays might be needed to see the action clearly.
If successful, shorter flashes of XFEL might mean longer lines at SLAC.
Evans is based at EMSL, the Environmental Molecular Sciences Laboratory at PNNL. This work was supported by the Department of Energy Office of Science, National Institutes of Health, National Science Foundation, Lawrence Livermore National Laboratory, and Pacific Northwest National Laboratory.
Reference: Matthias Frank, David B. Carlson, Mark S. Hunter, Garth J. Williams, Marc Messerschmidt, Nadia A. Zatsepin, Anton Barty, W. Henry Benner, Kaiqin Chu, Alexander T. Graf, Stefan P. Hau-Riege, Richard A. Kirian, Celestino Padeste, Tommaso Pardini, Bill Pedrini, Brent Segelke, M. Marvin Seibert, John C. H. Spence, Ching-Ju Tsai, Stephen M. Lane, Xiao]Dan Li, Gebhard Schertler, Sebastien Boutet, Matthew Coleman and James E. Evans. Femtosecond X-ray Diffraction from Two-Dimensional Protein Crystals, International Union of Crystallography Journal, Feb. 10, 2014, doi: 10.1107/S2052252514001444. (http://dx.doi.org/10.1107/S2052252514001444)
The Department of Energy'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.
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.
EMSL, the Environmental Molecular Sciences Laboratory, is a national scientific user facility sponsored by the Department of Energy's Office of Science. Located at Pacific Northwest National Laboratory in Richland, Wash., EMSL offers an open, collaborative environment for scientific discovery to researchers around the world. Its integrated computational and experimental resources enable researchers to realize important scientific insights and create new technologies. Follow EMSL on Facebook, LinkedIn and Twitter.
Interdisciplinary teams at Pacific Northwest National Laboratory address many of America's most pressing issues in energy, the environment and national security through advances in basic and applied science. PNNL employs 4,500 staff, has an annual budget of nearly $1 billion, and has been managed for the U.S. Department of Energy by Ohio-based Battelle since the laboratory's inception in 1965. For more, visit the PNNL's News Center, or follow PNNL on Facebook, LinkedIn and Twitter.
Mary Beckman | Newswise
Investigating cell membranes: researchers develop a substance mimicking a vital membrane component
25.05.2018 | Westfälische Wilhelms-Universität Münster
New approach: Researchers succeed in directly labelling and detecting an important RNA modification
30.04.2018 | Westfälische Wilhelms-Universität Münster
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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ESAs Envisat satellite was witness to the dramatic last days of what was once the worlds largest iceberg, as a violent Antarctic storm cracked a 160-km-long floe in two.
Another Envisat instrument known as MERIS acquired this optical image showing B-15A in the Ross Sea on 16 October 2003. The bottle-shaped iceberg can be seen centre. Below it is the Ross Ice Sheet from which the B-15 berg originated in March 2003. Left of B-15A is McMurdo Sound, location of US and New Zealand Antarctic bases.
Credits: ESA 2003
This ASAR image from 6 November 2003 clearly shows the split iceberg. The larger piece of B-15A retains the original name, while the other piece is called B-15J. Left of B-15A can be seen land - including the famous McMurdo Dry Valleys, and behind them the Transantarctic Mountains. Top of the picture is the floating Drygalski Ice Tongue, an example of ice draining from the David Glacier into the sea at a minimum rate of 150 metres a year.
Credits: ESA 2003
A series of Envisat Advanced Synthetic Aperture Radar (ASAR) instrument images acquired between mid-September and October record how the bottle-shaped iceberg B-15A was split by the onslaught of powerful storms, waves and ocean currents as its own weight kept it fixed on the floor of Antarcticas Ross Sea.
ASAR is especially useful for polar operations because its radar signal can pierce thick clouds and works through both day and night. Radar imagery charts surface roughness, so can easily differentiate between different ice types. Old ice – as on the surface of B-15A – is rougher than newly formed ice.
Frédéric Le Gall | ESA
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science 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....
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A killing jar is a device used by entomologists to kill captured insects quickly and with minimum damage. The jar, typically glass, must be hermetically sealable and one design has a thin layer of hardened plaster of paris on the bottom to absorb the killing agent. The killing agent will then slowly evaporate, allowing the jar to be used many times before needing to refresh the jar. The absorbent plaster of paris layer also helps prevent the agent sticking to and damaging insects. Crumpled paper tissue is also placed in the jar for the same reason. A second method utilises a wad of cotton or other absorbent material placed in the bottom of the jar. Liquid killing agent is then added until the absorbent material is nearly saturated. A piece of stiff paper or cardboard cut to fit the inside of the jar tightly is then pressed in.
The most common killing agents are ether, chloroform and ethyl acetate. Ethyl acetate has many advantages and is very widely used. Its fumes are less toxic to humans than those of the other agents and specimens will remain limp if they are left in an ethyl acetate killing jar for several days and the ethyl acetate is not allowed to entirely evaporate from the specimens. A disadvantage is that although the insects are quickly stunned by ethyl acetate it kills them slowly and specimens may revive if removed from the killing jar too soon. Potassium cyanide or other cyanide compounds including calcium cyanide are also used, but only by experts due to its extreme toxicity. It also has the disadvantages of making the specimens brittle when left in the jar for several hours and may also cause some discoloration of colored specimens. It does kill rapidly and the cyanide charge will last a long time. A few drops of acetic acid will increase the cyanide gas production. If the jar is not used for long periods it may dry out and produce little gas, therefore a few drops of water will also help get the process going again. The potassium cyanide slowly decomposes, releasing hydrogen cyanide. In former times, amateur entomolgists commonly used the thick green leaves of the Cherry Laurel (Prunus laurocerasus) which, crushed or finely sliced, will similarly release hydrogen cyanide.
- Smithers, C. N. 1988. The Handbook of Insect Collecting. ISBN 0-589-50288-3
- "Collecting and Preserving Insects and Mites: Tools and Techniques". USDA.
- Cherry Laurel [www-saps.plantsci.cam.ac.uk/trees/laurel.htm], Retrieved on 25 June 2018.
- Collecting and Preserving Insects and Mites: Tools and Techniques
- How to Collect and Prepare Forest Insect and Disease Organisms and Plant Specimens for Identification
- A.Tereshkin Killing Jar with pieces of rubber tube for absorption of chloroform.
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DDT or 2,2-bis( p -chlorophenyl)-1,1,1,-trichloroethane, chlorinated hydrocarbon compound used as an insecticide . First introduced during the 1940s, it killed insects that spread disease and fed on crops, and Swiss scientist Paul Müller was awarded the 1948 Nobel Prize in Physiology or Medicine for discovering (1939) DDT's insecticidal properties. DDT, however, is toxic to many animals, including humans, and it is not easily degraded into nonpoisonous substances and can remain in the environment and the food chain for prolonged periods. By the 1960s its harmful effects on the reproductive systems of fish and birds were apparent in the United States, where the insecticide had been heavily used for agricultural purposes. After the United States banned its use in 1972, the affected wildlife population recovered, particularly the bald eagle and the osprey. Nevertheless, DDT use continues in parts of the world, particularly in tropical regions, to control the mosquitoes that spread malaria . In 2001 the Stockholm Convention on Persistent Organic Pollutants called for the phasing out of DDT once a cost-effective alternative becomes available.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
See D. Kinkela, DDT and the American Century (2011).
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Major Advance in Human Proteins
News Dec 23, 2013
A group of researchers from Arizona State University are part of a larger team reporting a major advance in the study of human proteins that could open up new avenues for more effective drugs of the future. The work is being reported in this week’s Science magazine.
GPCR’s are a highly diverse group of membrane proteins that mediate cellular communication. Because of their involvement in key physiological and sensory processes in humans, they are thought to be prominent drug targets.
The method described in the paper was applied for the first time to this important class of proteins, for which the 2012 Nobel Prize was awarded to Brian Kobilka and Robert Lefkowitz, said John Spence, an ASU professor of physics. Spence is also the director of science at National Science Foundation’s BioXFEL Science and Technology Center, and a team member on the Science paper.
“These GPCR’s are the targets of a majority of drug molecules,” Spence said, but they are notoriously difficult to work with. This is the first time structural observations of the GPCR’s have been made at room temperature, allowing researchers to overcome several disadvantages of previous imaging methods of the proteins.
“Normally, protein crystallography is performed on frozen samples, to reduce the effects of radiation damage,” Spence said, “but this new work was based on an entirely new approach to protein crystallography, called SFX (Serial Femtosecond Crystallography), developed jointly by ASU, the Deutsches Elektronen-Synchrotron (DESY) and the SLAC National Accelerator Laboratory.
“This method uses brief pulses of x-rays instead of freezing the sample to avoid damage, and so it reveals the structure which actually occurs in a cell at room temperature, not the frozen structure,” Spence added. “The 50 femtosecond pulses (120 per second) ‘outrun’ radiation damage, giving a clear picture of the structure before it is vaporized by the beam.”
The femtosecond crystallography technique could enable researchers to view molecular dynamics at a time-scale never observed before. Spence said the method basically operates by collecting the scattering for the image so quickly that images are obtained before the sample is destroyed by the x-ray beam.
By "outrunning" radiation-damage processes in this way, the researchers can record the time-evolution of molecular processes at room temperature, he said.
Spence said ASU played a crucial role in the project described in Science, through the invention by Uwe Weierstall (an ASU physics professor) of an entirely new device for sample delivery suited to this class of proteins.
The lipic cubic phase (LCP) injector that Weierstall developed replaces the continuous stream of liquid (which sends a continuously refreshed stream of proteins across the pulsed x-ray beam) with a slowly moving viscous stream of ‘lipid cubic phase solution,’ which has the consistency of automobile grease.
“We call it our ‘toothpaste jet,’” Spence said.
He added that the LCP solves three problems associated with previous SFX work, which made this new work possible:
• The viscosity slows the flow rate so the crystals emerge at about the same rate as the x-ray pulses come along, hence no protein is wasted. This is important for the study of human protein, which is more costly than diamond on a per gram basis.
• The “hit rate” is very high. Nearly all x-ray pulses hit protein particles.
• Most important, LCP is itself a growth medium for protein nanocrystals.
“A big problem with the SFX work we have been doing over the past four years is that people did not know how to make the required nanocrystals,” Spence said. “Now it seems many can be grown in the LCP delivery medium itself.”
The international team reporting the advance in Science includes researchers from the Scripps Research Institute, La Jolla, Calif.; the Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany; the Department of Physics and the Department of Chemistry and Biochemistry at ASU, Tempe, Ariz.; SLAC National Accelerator Laboratory, Menlo Park, Calif.; Trinity College, Dublin, Ireland; Uppsala University, Sweden; University of Hamburg, Germany; and Center for Ultrafast Imaging, Hamburg, Germany.
The collaboration between the team at ASU and the research groups at the Scripps Research Institute led by Professor Vadim Cherzov was initiated by Petra Fromme at ASU as a collaboration between two of the membrane protein centers of the Protein Structure Initiative of the National Institute of Health (PSI:Biology) -- the Center for Membrane Proteins in Infectious Diseases (MPID) at ASU and Trinity College Dublin led by Petra Fromme, and the GPCR Network at Scripps led by Prof. Ray Stevens.
Fromme led the ASU group that helped plan the experiments, characterize the samples and assist with data collection. Other members of the ASU team include Daniel James, Dingjie Wang, Garrett Nelson, Uwe Weierstall, Nadia Zatsepin, Richard Kirian, Raimund Fromme, Shibom Basu, Christopher Kupitz, Kimberley Rendek, Ingo Grotjohann and John Spence.
Kidney Cancer Driver Could Lead to New Treatment StrategyNews
Scientists have uncovered a potential therapeutic target for kidney cancers that have a common genetic change. Scientists have known this genetic change can lead to an overabundance of blood vessels, which help feed nutrients to the tumors. Their latest finding shows a potential new cancer-driving pathway.READ MORE | <urn:uuid:2fe9cee2-5999-4c57-8f2a-17a557c24991> | 2.96875 | 1,243 | News Article | Science & Tech. | 30.491897 | 95,525,555 |
Biomineralized tissues, such as sea shells and bones, grow in a genetically programmed way to obtain specific shapes and compositions, which define the unique functionalities. The growth of biominerals usually takes place in aqueous media at ambient conditions. Material scientists are keen to adapt this process from nature for a cost-efficient and simple fabrication of inorganic based materials.
Scientists at ETH Zurich used a set of laser beams to create a honeycomb-like structure similar to that found in graphene. By loading ultracold atoms into this optical lattice, they can simulate electronic properties of this promising material. Such experiments may be used to identify electronic properties of materials which have yet to be discovered.
Cutting-edge artists from across the world will participate in the "Art of the Small", a juried exhibition held in conjunction with the Nanotech Commercialization Conference, April 4-5, 2012 at the American Tobacco Campus, in Durham, NC.
Researchers from Stanford University and the U.S. Department of Energy's SLAC National Accelerator Laboratory have created the first-ever system of 'designer electrons' - exotic variants of ordinary electrons with tunable properties that may ultimately lead to new types of materials and devices.
Using artificial DNA molecules, an international team of scientists headed by the Cluster of Excellence Nanosystems Initiative Munich has produced nanostructured materials that can be used to modify visible light by specification.
Experiments at SLAC's Linac Coherent Light Source (LCLS) have shown a promising new way to collect data on these elusive proteins. Researchers embedded tiny protein crystals in an oily paste that mimics the supportive environment of the cell membrane, and then hit them with a powerful X-ray laser to determine the protein's structure.
Imagine a test that sifts through millions of molecules in a drop of a patient's blood to detect a telltale protein signature of a cancer subtype, or a drug ferry that doesn't release its toxic contents until it slips inside cancer cells. These and other nanotechnologies could be game changers in how we diagnose, monitor and treat cancer. To more fully understand the impact, The Kavli Foundation held a roundtable conference with four pioneers in the field.
Silver nanoparticles cause more damage to testicular cells than titanium dioxide nanoparticles, according to a recent study by the Norwegian Institute of Public Health. However, the use of both types may affect testicular cells with possible consequences for fertility.
Die Kryo-Elektronentomografie ermoeglicht hochaufloesende, dreidimensionale Einblicke in das Innere von Zellen. Jedoch koennen damit nur sehr kleine Zellen oder duenne Randbereiche groesserer Zellern direkt untersucht werden. Wissenschaftler vom Max-Planck-Institut fuer Biochemie haben jetzt eine Methode entwickelt, um in nahezu unzugaengliche Zellbereiche vorzudringen. | <urn:uuid:1c751d11-fd4e-4df9-a032-941acdce9902> | 2.921875 | 647 | Content Listing | Science & Tech. | 18.436577 | 95,525,575 |
Status: Not Listed
An adult spotted salamander is dark brown or black with yellow or orange spots on its back and sides, and its belly is gray. This amphibian has a broad head and smooth skin with vertical grooves on both sides of its torso. Glands on their backs and tails release a sticky toxic liquid when the animal is threatened.
A spotted salamander's appearance differs depending on its life cycle stage. In its larval stage, the spotted salamander lives in the water and has external gills. The back is closer to a dull greenish color, and it has a mottled tail and a pale belly. When they hatch, larvae are approximately half an inch (1.25 centimeters) long. Spotted salamanders grow to be 6 to 10 inches (15 to 25 centimeters) long, with females tending to be larger than males.
Spotted salamanders can be found in the eastern United States along the Atlantic coast and throughout the southeastern states, with the exception of Florida. Their range extends west as far as Texas and north into eastern parts of Canada. They live in hardwood and mixed forests close to stagnant water sources like swamps, ponds, and vernal pools (temporary or seasonal pools of water). Their predators include skunks, raccoons, turtles, and snakes.
As larvae, spotted salamanders eat insects, small crustaceans, and other aquatic invertebrates. Adults have a sticky tongue to catch earthworms, snails, spiders, centipedes, and other invertebrates they find on the forest floor.
Spotted salamanders progress through several life stages: egg, larva, juvenile, and adult. Their eggs are laid underwater, so when the larvae hatch they have external gills for breathing in their aquatic environment, a broad tail to help them swim, and weak legs. The larvae feed in the water while they grow into juveniles. Juvenile and adult salamanders live on land and have lungs and strong legs. Spotted salamanders migrate to breeding ponds in late winter and early spring once temperatures begin to warm up and rain showers arrive.
Adult spotted salamanders live about 20 years, but some have been recorded to live as long as 30 years. Due to predators and disease, most spotted salamanders die before they reach the land-dwelling juvenile stage. Larvae in vernal pools will die if the water dries up before they grow into juveniles.
The spotted salamander population is considered stable, though some subpopulations are declining due to habitat loss. The International Union for Conservation of Nature estimates there are more than a million spotted salamanders in North America.
Spotted salamander eggs sometimes contain green algae. The algae will consume the carbon dioxide that salamander embryos produce and turn it into oxygen that the embryos can use.
Animal Diversity Web, University of Michigan Museum of Zoology
The IUCN Red List of Threatened Species
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From self-cleaning windows to personalised medicine, the promise of nanotechnology spans from the mundane to the lifesaving. But is nanotech really new? Should we be worried about it? And where to from here?
A nanometre, from the Greek ‘nanos’ meaning dwarf, is one billionth of a meter or 80,000 times smaller than the width of a human hair. Nanotechnology is the manipulation or manufacture of materials or devices at the scale of atoms or small groups of atoms. At this scale the material properties differ from the bulk, and we can control properties such as the conductivity or transparency by controlling the structure.
Join Rosie Hicks, CEO of the Australian National Fabrication Facility, for a fascinating talk on nanotechnology and its applications in Australian health, communications and energy.
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It is also a likely component in the Earth's mantle, and it plays an important role in the life cycle. But at high pressure, carbon dioxide can transform to a solid.
The commonly known solid-state form of carbon dioxide is the so called "dry ice", which is a molecular crystal and has many important applications, e.g. food producation and storage, artificial fog in theatre and artificial rainfall, etc.
Even more interesting, as the pressure increases and temperature varies, the intra- and inter-molecular interactions of carbon dioxide change dramatically and this results in different crystal structures in polymeric dense phases with interesting physical properties, such as "super-hardness". Thus carbon dioxide has become an extremely hot topic in science in the last decade.
Recently, a collaborative study between the research groups in Canada, Germany, Slovakia, Italy and USA achieved progress on this highly interested compound. Using a novel computer-based simulation method called metadynamics combined with accurate quantum mechanical calculations, they found that a molecular solid called CO2-II transfers to a layered polymeric structure at a pressure of 60 GPa (1 GPa is approximately 10000 atmospheres) and temperature at 600 Kelvin.
Based on the good agreement between their calculated Raman spectra and X-ray diffraction patterns and the previous experimental values, a new interpretation of a previous experimental result is given. A recently identified dense phase VI found in experiment, assumed to be disordered stishovite-like structure, is instead interpreted as the result of an incomplete transformation from the molecular phase into a final layered polymeric structure.
In addition, a new ?-cristobalite-like CO2 as found in silicon dioxide, is predicted to be formed from CO2-III via an intermediate structure at 80 GPa and temperature lower than room temperature. Defects in the crystals increase with temperature and CO2 transforms to an amorphous form when temperature is higher than room temperature, consistent with previous experiments.
These results obtained from fully dynamical simulations reveal hitherto unknown microscopic transformation mechanisms, and illustrate the transformation from a molecular solid characterized by only intra-molecular bonding to a polymerized structure. The transformation takes place at pressures within the range found in the Earth's mantle, where a significant amount of oxidized carbon is thought to be present, either in the form of carbonates or as a fluid. The large and abrupt changes in the bonding properties of CO2 reported here hint to possible discontinuities in the carbon chemistry of the mantle. Their article by Dr. Jian Sun et al. is soon to be (has been) published in the prestigious journal - Proceedings of the National Academy of Sciences USA.
Jian Sun, Dennis D. Klug, Roman Martonak, Javier Antonio Montoya, Mal-Soon Lee, Sandro Scandolo and Erio Tosatti: High-pressure polymeric phases of carbon dioxide. In: PNAS early edition, http://www.pnas.org_cgi_doi_10.1073_pnas.0812624106
Dr. Jian Sun, Lehrstuhl für Theoretische Chemie der Ruhr-Universität Bochum, D-44780 Bochum, Tel. +49 (0)234 32 22121, E-Mail: email@example.com
Dr. Josef König | idw
Further reports about: > CO2 > CO2-II transfers > Earth's mantle > GPa > Sun > artificial fog > artificial rainfall > carbon dioxide > computer-based simulation method > dry ice > earth's atmosphere > intra- and inter-molecular interactions > metadynamics > molecular crystal > polymeric materials > quantum mechanical calculations > room temperature > stishovite-like structure > super-hardness
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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.
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